SEMICONDUCTOR STRUCTURE AND MANUFACTURING METHOD THEREOF

Abstract

A semiconductor structure and a manufacturing method thereof are provided. The manufacturing method includes the following steps. A trench is formed in a first interlayer dielectric (ILD) layer. A metal conductor with metal dopants is filled in the trench. Planarization is performed on the metal conductor with the metal dopants. A thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor with the metal dopants to form a self-forming metal capping layer on a first metal layer. An etching stop bi-layer structure is formed on the first interlayer dielectric layer and the self-forming metal capping layer. A via, a second interlayer dielectric (ILD) layer and a second metal layer are formed on the etching stop bi-layer structure. The via is embedded in the second interlayer dielectric layer and the via is disposed between the first metal layer and the second metal layer.

Claims

1. A manufacturing method of a semiconductor structure, comprising: forming a trench in a first interlayer dielectric (ILD) layer; filling a metal conductor with metal dopants in the trench; performing planarization on the metal conductor with the metal dopants; performing a thermal treatment, a photo treatment or a bias-assist treatment on the metal conductor with the metal dopants to form a self-forming metal capping layer on a first metal layer; forming an etching stop bi-layer structure on the first interlayer dielectric layer and the self-forming metal capping layer; forming a via, a second interlayer dielectric (ILD) layer and a second metal layer on the etching stop bi-layer structure, wherein the via is embedded in the second interlayer dielectric layer and the via is disposed between the first metal layer and the second metal layer.

2. The manufacturing method of the semiconductor structure according to claim 1, wherein a material of the metal dopants is Vanadium (V), Niobium (Nb), Molybdenum (Mo), Tungsten (W) or Manganese (Mn).

3. The manufacturing method of the semiconductor structure according to claim 1, wherein in the filling the metal conductor with the metal dopants in the trench, the metal conductor with the metal dopants is filled by Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP) or Electroless plating.

4. The manufacturing method of the semiconductor structure according to claim 1, wherein in the filling the metal conductor with the metal dopants in the trench, a process temperature is 10 C. to 400 C.

5. The manufacturing method of the semiconductor structure according to claim 1, wherein the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage.

6. The manufacturing method of the semiconductor structure according to claim 1, wherein in the performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-forming metal capping layer on the first metal layer, a process temperature is 10 C. to 400 C.

7. The manufacturing method of the semiconductor structure according to claim 1, wherein a process temperature in the filling the metal conductor with the metal dopants in the trench is lower than a process temperature in the performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-forming metal capping layer on the first metal layer.

8. The manufacturing method of the semiconductor structure according to claim 1, wherein a thickness of the self-forming metal capping layer is 1 to 100 m.

9. A manufacturing method of a semiconductor structure, comprising: forming a trench in a first interlayer dielectric (ILD) layer; filling a metal conductor with metal dopants in the trench; performing planarization on the metal conductor with the metal dopants; forming a metal capping layer on the metal conductor with the metal dopants; performing a thermal treatment, a photo treatment or a bias-assist treatment on the metal conductor with the metal dopants to form a self-aligned etching stop layer and a first metal layer, wherein the self-aligned etching stop layer is formed on the metal capping layer; forming a conformal etching stop layer on the first interlayer dielectric layer and the self-aligned etching stop layer to form an etching stop bi-layer structure; and forming a via, a second interlayer dielectric (ILD) layer and a second metal layer, wherein the via is embedded in the second interlayer dielectric layer and the via is disposed between the first metal layer and the second metal layer.

10. The manufacturing method of the semiconductor structure according to claim 9, wherein a material of the metal dopants is Zirconium (Zr) or Aluminum (Al).

11. The manufacturing method of the semiconductor structure according to claim 9, wherein in the filling the metal conductor with the metal dopants in the trench, the metal conductor with the metal dopants is filled by Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP) or Electroless plating.

12. The manufacturing method of the semiconductor structure according to claim 9, wherein in the filling the metal conductor with the metal dopants in the trench, a process temperature is 10 C. to 400 C.

13. The manufacturing method of the semiconductor structure according to claim 9, wherein the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage.

14. The manufacturing method of the semiconductor structure according to claim 9, wherein a thickness of the self-aligned etching stop layer is 1 to 100 m.

15. The manufacturing method of the semiconductor structure according to claim 9, wherein in the performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-aligned etching stop layer and the first metal layer, a process temperature is 10 C. to 400 C.

16. A semiconductor structure, comprising: a first interlayer dielectric (ILD) layer; a first metal layer, embedded in the first interlayer dielectric layer; a metal capping layer, disposed on the first metal layer; an etching stop bi-layer structure, including: a self-aligned etching stop layer, disposed on the metal capping layer; and a conformal etching stop layer, disposed on the first interlayer dielectric layer and the self-aligned etching stop layer; a second interlayer dielectric (ILD) layer, disposed on the etching stop bi-layer structure; a via, embedded in the second interlayer dielectric layer; and a second metal layer, embedded in the second interlayer dielectric layer and disposed on the via.

17. The semiconductor structure according to claim 16, wherein a material of the self-aligned etching stop layer is Zirconium oxide (ZrO2) or Aluminum oxide (Al).

18. The semiconductor structure according to claim 16, wherein a thickness of the self-aligned etching stop layer is 1 to 100 m.

19. The semiconductor structure according to claim 16, wherein the self-aligned etching stop layer only covers the metal capping layer.

20. The semiconductor structure according to claim 16, wherein the etching stop bi-layer structure further includes: a first hermetic layer, disposed between the first interlayer dielectric layer and the conformal etching stop layer, and disposed between the self-aligned etching stop layer and the conformal etching stop layer; and a second hermetic layer, disposed on the conformal etching stop layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0005] FIG. 1 shows a semiconductor structure A-1 according to one embodiment.

[0006] FIG. 2 shows a semiconductor structure A-2 according to another embodiment.

[0007] FIG. 3 shows a semiconductor structure A-3 according to another embodiment.

[0008] FIG. 4 shows a semiconductor structure B-1 according to another embodiment.

[0009] FIG. 5 shows a semiconductor structure B-2 according to another embodiment.

[0010] FIG. 6 shows a semiconductor structure B-3 according to another embodiment.

[0011] FIG. 7 shows a semiconductor structure B-4 according to another embodiment.

[0012] FIG. 8 shows a semiconductor structure B-5 according to another embodiment.

[0013] FIG. 9 shows a semiconductor structure B-6 according to another embodiment.

[0014] FIG. 10 shows a semiconductor structure B-7 according to another embodiment.

[0015] FIG. 11 shows a semiconductor structure B-8 according to another embodiment.

[0016] FIG. 12 shows a semiconductor structure B-9 according to another embodiment.

[0017] FIG. 13 shows a semiconductor structure C-1 according to one embodiment.

[0018] FIG. 14 shows a semiconductor structure C-2 according to one embodiment.

[0019] FIG. 15 shows a semiconductor structure C-3 according to one embodiment.

[0020] FIG. 16 shows a semiconductor structure D-1 according to another embodiment.

[0021] FIG. 17 shows a semiconductor structure D-2 according to another embodiment.

[0022] FIG. 18 shows a semiconductor structure D-3 according to another embodiment.

[0023] FIG. 19 shows a semiconductor structure D-4 according to another embodiment.

[0024] FIG. 20 shows a semiconductor structure D-5 according to another embodiment.

[0025] FIG. 21 shows a semiconductor structure D-6 according to another embodiment.

[0026] FIG. 22 shows a semiconductor structure D-7 according to another embodiment.

[0027] FIG. 23 shows a semiconductor structure D-8 according to another embodiment.

[0028] FIG. 24 shows a semiconductor structure D-9 according to another embodiment.

[0029] FIGS. 25A to 25I illustrate a manufacturing method of the semiconductor structure A-1.

[0030] FIGS. 26A to 26E illustrate a manufacturing method of the semiconductor structure A-2.

[0031] FIGS. 27A to 27F illustrate a manufacturing method of the semiconductor structure A-3.

[0032] FIGS. 28A to 28M illustrate a manufacturing method of the semiconductor structure B-1.

[0033] FIGS. 29A to 290 illustrate a manufacturing method of the semiconductor structure B-9.

[0034] FIGS. 30A to 30J illustrate a manufacturing method of the semiconductor structure C-1.

[0035] FIGS. 31A to 31F illustrate a manufacturing method of the semiconductor structure C-2.

[0036] FIGS. 32A to 32G illustrate a manufacturing method of the semiconductor structure C-3.

[0037] FIGS. 33A to 33P illustrate a manufacturing method of the semiconductor structure D-1.

[0038] FIGS. 34A to 34K illustrate a manufacturing method of the semiconductor structure D-3.

DETAILED DESCRIPTION

[0039] The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

[0040] Further, spatially relative terms, such as beneath, below, lower, above, upper and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0041] Please refer to FIG. 1, which shows a semiconductor structure A-1 according to one embodiment. The semiconductor structure A-1 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure A-1 includes, for example, a interlayer dielectric (ILD) layer ILD1, a barrier layer BR1, a liner layer LN1, the metal layer MT1, a self-forming metal capping layer CP1, an etching stop bi-layer structure ESBS1, a interlayer dielectric layer ILD2, a barrier layer BR2, a liner layer LN2, a via VA and the metal layer MT2.

[0042] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The material of the interlayer dielectric layer ILD1 is, for example, silicon oxide (SiO), silicon oxycarbide (SiCO), silicon carbon nitride (SiCN), silicon oxycarbonitride (SiCON), silicon oxynitride (SiNO), silicon nitride (SiN), the like or a combination thereof. The material of the metal layer MT1 is, for example, tungsten (W), ruthenium (Ru), cobalt (Co), copper (Cu), aluminum (Al), nickel (Ni), gold (Au), silver (Ag), gold-aluminum (AuAl), molybdenum (Mo), the like, or a combination thereof.

[0043] The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1. The material of the barrier layer BR1 is, for example, titanium nitride (TiN), tantalum nitride (TaN) or silicon nitride (SiN), the like, or a combination thereof. The material of the liner layer LN1 is, for example, cobalt (Co), or the like.

[0044] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. The material of the self-forming metal capping layer CP1 is, for example, vanadium (V), niobium (Nb), molybdenum (Mo), tungsten (W), manganese (Mn), the like, or a combination thereof. In this embodiment, the self-forming metal capping layer CP1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0045] The etching stop bi-layer structure ESBS1 includes, for example, a conformal etching stop layer ESL1, a hermetic layer HM1, a conformal etching stop layer ESL2, and a hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. The material of the conformal etching stop layer ESL1 and the conformal etching stop layer ESL2 is, for example, silicon carbon nitride (SiCxNy), boron nitride (BN), boron carbonitride (BCN), silicon oxycarbonitride (SiOCN), silicon oxycarbide (SiOC), the like, or a combination thereof. The material of the hermetic layer HM1 and the hermetic layer HM2 is, for example, nitride, oxide, polyimide, polybenzoxazole, the like, or a combination thereof.

[0046] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2. The material of the interlayer dielectric layer ILD2 is, for example, silicon oxide (SiO), silicon oxycarbide (SiCO), silicon carbon nitride (SiCN), silicon oxycarbonitride (SiCON), silicon oxynitride (SiNO), silicon nitride (SiN), the like or a combination thereof. The material of the metal layer MT2 is, for example, tungsten (W), ruthenium (Ru), cobalt (Co), copper (Cu), aluminum (Al), nickel (Ni), gold (Au), silver (Ag), gold-aluminum (AuAl), molybdenum (Mo), the like, or a combination thereof.

[0047] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, between the interlayer dielectric layer ILD2 and the metal layer MT2, and between the via VA and the self-forming metal capping layer CP1. The material of the barrier layer BR2 is, for example, titanium nitride (TiN), tantalum nitride (TaN) or silicon nitride (SiN), the like, or a combination thereof. The material of the liner layer LN1 is, for example, cobalt (Co), or the like.

[0048] In the embodiment shown in the FIG. 1, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0049] Please refer to FIG. 2, which shows a semiconductor structure A-2 according to another embodiment. The semiconductor structure A-2 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure A-2 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD2, a barrier layer BR2, the liner layer LN2, the via VA and the metal layer MT2.

[0050] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0051] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0052] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0053] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2.

[0054] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, between the interlayer dielectric layer ILD2 and the metal layer MT2. Only the liner layer LN2 is disposed between the via VA and the self-forming metal capping layer CP1.

[0055] In the embodiment shown in the FIG. 2, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0056] Please refer to FIG. 3, which shows a semiconductor structure A-3 according to another embodiment. The semiconductor structure A-3 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure A-3 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD2, the barrier layer BR2, a liner layer LN2, the via VA and the metal layer MT2.

[0057] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0058] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0059] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0060] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2.

[0061] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, and between the interlayer dielectric layer ILD2 and the metal layer MT2. The via VA is directly connected to the self-forming metal capping layer CP1 and the barrier layer BR2 and the liner layer LN2 are not disposed between the via VA and the self-forming metal capping layer CP1.

[0062] In the embodiment shown in the FIG. 3, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0063] Please refer to FIG. 4, which shows a semiconductor structure B-1 according to another embodiment. The semiconductor structure B-1 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-1 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, a barrier layer BR21, a liner layer LN21, the via VA, a self-forming metal capping layer CP2, an etching stop bi-layer structure ESBS2, an interlayer dielectric layer ILD22, a barrier layer BR22, a liner layer LN22 and the metal layer MT2.

[0064] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0065] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0066] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0067] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0068] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the self-forming metal capping layer CP1.

[0069] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. The material of the self-forming metal capping layer CP2 is, for example, vanadium (V), niobium (Nb), molybdenum (Mo), tungsten (W), manganese (Mn), the like, or a combination thereof. In this embodiment, the self-forming metal capping layer CP2 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0070] The etching stop bi-layer structure ESBS2 includes, for example, a conformal etching stop layer ESL3, a hermetic layer HM3, a conformal etching stop layer ESL4, and a hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4. The material of the conformal etching stop layer ESL3 and the conformal etching stop layer ESL4 is, for example, silicon carbon nitride (SiCxNy), boron nitride (BN), boron carbonitride (BCN), silicon oxycarbonitride (SiOCN), silicon oxycarbide (SiOC), the like, or a combination thereof. The material of the hermetic layer HM3 and the hermetic layer HM4 is, for example, nitride, oxide, polyimide, polybenzoxazole, the like, or a combination thereof.

[0071] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22. The material of the interlayer dielectric layer ILD22 is, for example, silicon oxide (SiO), silicon oxycarbide (SiCO), silicon carbon nitride (SiCN), silicon oxycarbonitride (SiCON), silicon oxynitride (SiNO), silicon nitride (SiN), the like or a combination thereof.

[0072] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the self-forming metal capping layer CP2 and the metal layer MT2.

[0073] In the embodiment shown in the FIG. 4, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0074] Please refer to FIG. 5, which shows a semiconductor structure B-2 according to another embodiment. The semiconductor structure B-2 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-2 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, a barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0075] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0076] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0077] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0078] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0079] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the self-forming metal capping layer CP1.

[0080] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0081] The etching stop bi-layer structure ESBS2 includes, for example, a conformal etching stop layer ESL3, a hermetic layer HM3, a conformal etching stop layer ESL4, and a hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0082] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0083] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the self-forming metal capping layer CP2 and the metal layer MT2, and the barrier layer BR22 is not located between the self-forming metal capping layer CP2 and the metal layer MT2.

[0084] In the embodiment shown in the FIG. 5, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0085] Please refer to FIG. 6, which shows a semiconductor structure B-3 according to another embodiment. The semiconductor structure B-3 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-3 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, a liner layer LN22 and the metal layer MT2.

[0086] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0087] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0088] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0089] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0090] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the self-forming metal capping layer CP1.

[0091] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0092] The etching stop bi-layer structure ESBS2 includes, for example, a conformal etching stop layer ESL3, a hermetic layer HM3, a conformal etching stop layer ESL4, and a hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0093] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0094] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the self-forming metal capping layer CP2. The barrier BR22 and the liner layer LN22 are not disposed between the self-forming metal capping layer CP2 and the metal layer MT2.

[0095] In the embodiment shown in the FIG. 6, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0096] Please refer to FIG. 7, which shows a semiconductor structure B-4 according to another embodiment. The semiconductor structure B-4 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-4 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, a barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0097] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0098] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0099] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0100] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0101] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the self-forming metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the self-forming metal capping layer CP1.

[0102] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0103] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0104] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0105] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the self-forming metal capping layer CP2 and the metal layer MT2.

[0106] In the embodiment shown in the FIG. 7, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0107] Please refer to FIG. 8, which shows a semiconductor structure B-5 according to another embodiment. The semiconductor structure B-5 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-5 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, a barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0108] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0109] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0110] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0111] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0112] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the self-forming metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the self-forming metal capping layer CP1.

[0113] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0114] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0115] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0116] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the self-forming metal capping layer CP2 and the metal layer MT2. The barrier layer BR22 is not disposed between the self-forming metal capping layer CP2 and the metal layer MT2.

[0117] In the embodiment shown in the FIG. 8, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0118] Please refer to FIG. 9, which shows a semiconductor structure B-6 according to another embodiment. The semiconductor structure B-6 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-6 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, a liner layer LN22 and the metal layer MT2.

[0119] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0120] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0121] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0122] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0123] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the self-forming metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the self-forming metal capping layer CP1.

[0124] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0125] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0126] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22. The material of the interlayer dielectric layer ILD22 is, for example, silicon oxide (SiO), silicon oxycarbide (SiCO), silicon carbon nitride (SiCN), silicon oxycarbonitride (SiCON), silicon oxynitride (SiNO), silicon nitride (SiN), the like or a combination thereof.

[0127] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the self-forming metal layer CP2. The barrier layer BR22 and liner layer LN22s are not disposed between the self-forming metal capping layer CP2 and the metal layer MT2.

[0128] In the embodiment shown in the FIG. 9, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0129] Please refer to FIG. 10, which shows a semiconductor structure B-7 according to another embodiment. The semiconductor structure B-7 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-7 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, the barrier layer BR21, a liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0130] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0131] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0132] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0133] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0134] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the self-forming metal layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the self-forming metal capping layer CP1.

[0135] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0136] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0137] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0138] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the self-forming metal capping layer CP2 and the metal layer MT2.

[0139] In the embodiment shown in the FIG. 10, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0140] Please refer to FIG. 11, which shows a semiconductor structure B-8 according to another embodiment. The semiconductor structure B-8 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-8 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0141] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0142] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0143] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0144] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0145] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the self-forming metal layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the self-forming metal capping layer CP1.

[0146] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0147] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0148] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0149] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the metal layer MT2 and the self-forming metal capping layer CP2. The barrier layer BR22 is not disposed between the metal layer MT2 and the self-forming metal capping layer CP2.

[0150] In the embodiment shown in the FIG. 11, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0151] Please refer to FIG. 12, which shows a semiconductor structure B-9 according to another embodiment. The semiconductor structure B-9 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure B-9 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the self-forming metal capping layer CP1, the etching stop bi-layer structure ESBS1, an interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the self-forming metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0152] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0153] The self-forming metal capping layer CP1 is disposed on the metal layer MT1. The self-forming metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the self-forming metal capping layer CP1 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon.

[0154] The etching stop bi-layer structure ESBS1 includes, for example, the conformal etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The conformal etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2.

[0155] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0156] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the self-forming metal layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the self-forming metal capping layer CP1.

[0157] The self-forming metal capping layer CP2 is disposed on the via VA. The self-forming metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the self-forming metal capping layer CP2 is formed through the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC2. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal conductor to form the via VA and the self-forming metal capping layer CP2 disposed thereon.

[0158] The etching stop bi-layer structure ESBS2 includes, for example, the conformal etching stop layer ESL3, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. The conformal etching stop layer ESL3 is disposed on the interlayer dielectric layer ILD21. The hermetic layer HM3 is disposed on the conformal etching stop layer ESL3. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0159] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0160] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the self-forming metal capping layer CP2. The barrier layer BR22 and the liner layer LN22 are not disposed between the metal layer MT2 and the self-forming metal capping layer CP2.

[0161] In the embodiment shown in the FIG. 12, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0162] Please refer to FIG. 13, which shows a semiconductor structure C-1 according to one embodiment. The semiconductor structure C-1 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure C-1 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, a metal capping layer CP1, an etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD2, the barrier layer BR2, the liner layer LN2, the via VA and the metal layer MT2.

[0163] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1.

[0164] The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0165] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. The material of the metal capping layer CP1 is, for example, cobalt (Co), graphene, nickel (Ni), tin (SN), tin-lead (SnPb), gold (Au), copper (Cu), silver (Ag), palladium (Pd), indium (In), nickel-palladium-gold (NiPdAu), nickel-gold (NiAu), the like, or a combination thereof. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0166] The etching stop bi-layer structure ESBS1 includes, for example, a self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. A thickness of the self-aligned etching stop layer ESL1 is 1 to 100 m. The material of the self-aligned etching stop layer ESL1 is Zirconium oxide (ZrO2) or Aluminum oxide (Al). In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0167] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2.

[0168] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, between the interlayer dielectric layer ILD2 and the metal layer MT2, and between the via VA and the metal capping layer CP1.

[0169] In the embodiment shown in the FIG. 13, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0170] Please refer to FIG. 14, which shows a semiconductor structure C-2 according to one embodiment. The semiconductor structure C-2 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure C-2 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD2, the barrier layer BR2, the liner layer LN2, the via VA and the metal layer MT2.

[0171] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1.

[0172] The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0173] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0174] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0175] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2.

[0176] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, between the interlayer dielectric layer ILD2 and the metal layer MT2, and between the via VA and the metal capping layer CP1.

[0177] In the embodiment shown in the FIG. 14, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0178] Please refer to FIG. 15, which shows a semiconductor structure C-3 according to one embodiment. The semiconductor structure C-3 is an interconnection for two metal layers MT1, MT2 with dual damascene in the back-end-of-line (BEOL) process. The semiconductor structure C-3 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD2, the barrier layer BR2, the liner layer LN2, the via VA and the metal layer MT2.

[0179] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1.

[0180] The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0181] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0182] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0183] The interlayer dielectric layer ILD2 is disposed on the etching stop bi-layer structure ESBS1. The via VA and the metal layer MT2 are embedded in the interlayer dielectric layer ILD2.

[0184] The barrier layer BR2 and the liner layer LN2 are disposed between the interlayer dielectric layer ILD2 and the via VA, and between the interlayer dielectric layer ILD2 and the metal layer MT2. The metal layer MT2 is directly connected to the via VA. The barrier layer BR2 and the liner layer LN2 are not disposed between the via VA and the metal capping layer CP1.

[0185] In the embodiment shown in the FIG. 15, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0186] Please refer to FIG. 16, which shows a semiconductor structure D-1 according to another embodiment. The semiconductor structure D-1 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-1 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0187] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0188] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0189] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0190] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0191] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the metal capping layer CP1.

[0192] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0193] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0194] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0195] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the metal capping layer CP2 and the metal layer MT2.

[0196] In the embodiment shown in the FIG. 16, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0197] Please refer to FIG. 17, which shows a semiconductor structure D-2 according to another embodiment. The semiconductor structure D-2 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-2 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0198] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0199] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0200] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0201] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0202] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the metal capping layer CP1.

[0203] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0204] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0205] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0206] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the metal capping layer CP2 and the metal layer MT2. The barrier layer BR22 is not disposed between the metal capping layer CP2 and the metal layer MT2.

[0207] In the embodiment shown in the FIG. 17, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-2. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0208] Please refer to FIG. 18, which shows a semiconductor structure D-3 according to another embodiment. The semiconductor structure D-3 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-3 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, the metal capping layer CP2, the etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0209] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0210] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0211] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0212] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0213] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA, and between the via VA and the metal capping layer CP1.

[0214] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0215] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0216] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0217] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the metal capping layer CP2. The barrier layer BR22 and the liner layer LN22 are not disposed between the metal capping layer CP2 and the metal layer MT2.

[0218] In the embodiment shown in the FIG. 18, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-3. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0219] Please refer to FIG. 19, which shows a semiconductor structure D-4 according to another embodiment. The semiconductor structure D-4 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-4 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0220] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0221] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0222] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0223] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0224] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the metal capping layer CP1.

[0225] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0226] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0227] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0228] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the metal capping layer CP2 and the metal layer MT2.

[0229] In the embodiment shown in the FIG. 19, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-4. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0230] Please refer to FIG. 20, which shows a semiconductor structure D-5 according to another embodiment. The semiconductor structure D-5 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-5 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0231] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0232] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0233] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0234] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0235] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the metal capping layer CP1.

[0236] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0237] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0238] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0239] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the metal capping layer CP2 and the metal layer MT2. The barrier layer BR22 is not disposed between the metal capping layer CP2 and the metal MT2.

[0240] In the embodiment shown in the FIG. 20, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-5. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0241] Please refer to FIG. 21, which shows a semiconductor structure D-6 according to another embodiment. The semiconductor structure D-6 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-6 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0242] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0243] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0244] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0245] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0246] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. Only the liner layer LN21 is disposed between the via VA and the metal capping layer CP1. The barrier layer BR21 is not disposed between the via VA and the metal capping layer CP1.

[0247] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0248] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0249] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0250] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the metal capping layer CP2. The barrier layer BR22 and the liner layer LN22 are not disposed between the metal capping layer CP2 and the metal layer MT2.

[0251] In the embodiment shown in the FIG. 21, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-6. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0252] Please refer to FIG. 22, which shows a semiconductor structure D-7 according to another embodiment. The semiconductor structure D-7 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-7 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0253] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0254] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0255] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL disposed on the metal capping layer CP1.

[0256] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0257] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the metal capping layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the metal capping layer CP1.

[0258] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0259] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0260] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0261] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, between the interlayer dielectric layer ILD21 and the metal layer MT2, and between the metal capping layer CP2 and the metal layer MT2.

[0262] In the embodiment shown in the FIG. 22, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-7. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0263] Please refer to FIG. 23, which shows a semiconductor structure D-8 according to another embodiment. The semiconductor structure D-8 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-8 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0264] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0265] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0266] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0267] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0268] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the metal capping layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the metal capping layer CP1.

[0269] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0270] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0271] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0272] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. Only the liner layer LN22 is disposed between the metal layer MT2 and the metal capping layer CP2. The barrier layer BR22 is not disposed between the metal layer MT2 and the metal capping layer CP2.

[0273] In the embodiment shown in the FIG. 23, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-8. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0274] Please refer to FIG. 24, which shows a semiconductor structure D-9 according to another embodiment. The semiconductor structure D-9 is an interconnection for two metal layers MT1, MT2 with single damascene in the back-end-of-line (BEOL) process. The semiconductor structure D-9 includes, for example, the interlayer dielectric (ILD) layer ILD1, the barrier layer BR1, the liner layer LN1, the metal layer MT1, the metal capping layer CP1, the etching stop bi-layer structure ESBS1, the interlayer dielectric layer ILD21, the barrier layer BR21, the liner layer LN21, the via VA, a metal capping layer CP2, an etching stop bi-layer structure ESBS2, the interlayer dielectric layer ILD22, the barrier layer BR22, the liner layer LN22 and the metal layer MT2.

[0275] The metal layer MT1 is embedded in the interlayer dielectric layer ILD1. The barrier layer BR1 and the liner layer LN1 are disposed between the metal layer MT1 and the interlayer dielectric layer ILD1.

[0276] The metal capping layer CP1 is disposed on the metal layer MT1. The metal capping layer CP1 only covers the metal layer MT1 and does not cover the interlayer dielectric layer ILD1. In this embodiment, the metal capping layer CP1 may be formed through the selective deposition.

[0277] The etching stop bi-layer structure ESBS1 includes, for example, the self-aligned etching stop layer ESL1, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2. The self-aligned etching stop layer ESL1 is disposed on the interlayer dielectric layer ILD1 and the metal capping layer CP1. The hermetic layer HM1 is disposed on the conformal etching stop layer ESL1. The conformal etching stop layer ESL2 is disposed on the hermetic layer HM1. The hermetic layer HM2 is disposed on the conformal etching stop layer ESL2. In this embodiment, the self-aligned etching stop layer ESL1 is formed through a thermal treatment, a photo treatment or a bias-assist treatment on a metal conductor with metal dopants. The metal conductor with the metal dopants is filled in the trench TC1. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1 disposed on the metal capping layer CP1.

[0278] The interlayer dielectric layer ILD21 is disposed on the etching stop bi-layer structure ESBS1. The via VA is embedded in the interlayer dielectric layer ILD21.

[0279] The barrier layer BR21 and the liner layer LN21 are disposed between the interlayer dielectric layer ILD21 and the via VA. The via VA is directly connected to the metal capping layer CP1. The barrier layer BR21 and the liner layer LN21 are not disposed between the via VA and the metal capping layer CP1.

[0280] The metal capping layer CP2 is disposed on the via VA. The metal capping layer CP2 only covers the via VA and does not cover the interlayer dielectric layer ILD21. In this embodiment, the metal capping layer CP2 may be formed through the selective deposition.

[0281] The etching stop bi-layer structure ESBS2 includes, for example, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4. A self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed. The hermetic layer HM3 is disposed on the interlayer dielectric layer ILD21. The conformal etching stop layer ESL4 is disposed on the hermetic layer HM3. The hermetic layer HM4 is disposed on the conformal etching stop layer ESL4.

[0282] The interlayer dielectric layer ILD22 is disposed on the etching stop bi-layer structure ESBS2. The metal layer MT2 is embedded in the interlayer dielectric layer ILD22.

[0283] The barrier layer BR22 and the liner layer LN22 are disposed between the interlayer dielectric layer ILD22 and the metal layer MT2, and between the interlayer dielectric layer ILD21 and the metal layer MT2. The metal layer MT2 is directly connected to the metal capping layer CP2. The barrier layer BR22 and the liner layer LN22 are not disposed between the metal layer MT2 and the metal capping layer CP2.

[0284] In the embodiment shown in the FIG. 24, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-9. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0285] Please refer to FIGS. 25A to 25I, which illustrate a manufacturing method of the semiconductor structure A-1. As shown in the FIG. 25A, the trench TC1 is formed in the interlayer dielectric (ILD) layer ILD1 and the barrier layer BR1 and the liner layer LN1 are formed on the interlayer dielectric layer ILD1, the bottom surface of the trench TC1 and the later-wall of the trench TC1. In this step, the trench TC1 could be formed, for example, by wet etching, dry etching or other suitable process. Moreover, the barrier layer BR1 and the liner layer LN1 could be formed, for example, by Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), plating or other suitable processes.

[0286] Next, as shown in the FIG. 25B, the metal conductor MC1 with metal dopants dp1 is filled in the trench TC1. In this step, the metal conductor MC1 with the metal dopants dp1 could be filled by, for example, Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP), Electroless plating, or other suitable processes. In this step, a process temperature is 10 C. to 400 C.

[0287] Then, as shown in the FIG. 25C, the planarization is performed on the metal conductor MC1 with the metal dopants dp1. In this step, the planarization could be performed by, for example, Chemical-Mechanical Planarization (CMP) or other suitable processes.

[0288] Next, as shown in the FIG. 25D, a thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor MC1 with the metal dopants dp1 to form the self-forming metal capping layer CP1 on the metal layer MT1. In this step, the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants dp1 will be gathered at the top of the metal conductor MC1 to form the metal layer MT1 and the self-forming metal capping layer CP1 disposed thereon. In this step, a process temperature is 10 C. to 400 C. The process temperature in the step shown in the FIG. 25B is lower than the process temperature in the step shown in the FIG. 25D.

[0289] Afterwards, as shown in the FIG. 25E, the etching stop bi-layer structure ESBS1 is formed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1.

[0290] Next, as shown in the FIG. 25F, the interlayer dielectric layer ILD2 is formed on the etching stop bi-layer structure ESBS1. In this step, the interlayer dielectric layer ILD2 could be formed, for example, by spin coating, Plasma Enhanced Chemical Vapor Deposition (PECVD), Plasma Enhanced Atomic Layer Deposition (PEALD) or other suitable process.

[0291] Then, as shown in the FIG. 25G, the trench TC2 is formed in the interlayer dielectric layer ILD2. The trench TC2 exposes the self-forming metal capping layer CP1. In this step, the trench TC2 could be formed, for example, by wet etching, dry etching or other suitable process.

[0292] Next, as shown in the FIG. 25H, the barrier layer BR2 and the liner layer LN2 are formed on the interlayer dielectric layer ILD2, the bottom surface of the trench TC2 and the later-wall of the trench TC2. The barrier layer BR2 and the liner layer LN2 could be formed, for example, by Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), plating or other suitable processes.

[0293] Then, as shown in the FIG. 25I, the via VA and the metal layer MT2 are formed on in the trench TC2. As such, the semiconductor structure A-1 is formed through the FIGS. 25A to 25I.

[0294] In the embodiment shown in the FIGS. 25A to 25I, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0295] Please refer to FIGS. 26A to 26E, which illustrate a manufacturing method of the semiconductor structure A-2. As shown in the FIG. 26A, the trench TC2 is formed in the interlayer dielectric layer ILD2.

[0296] Next, as shown in the FIG. 26B, a blocking layer BK1 is formed on the self-forming metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0297] Then, as shown in the FIG. 26C, the barrier layer BR2 is formed on the interlayer dielectric layer ILD2 and the lateral wall of the trench TC2, and then the blocking layer BK1 is removed.

[0298] Next, as shown in the FIG. 26D, the liner layer LN1 is formed on the barrier layer BR2 and the self-forming metal capping layer CP1.

[0299] Afterwards, as shown in the FIG. 26E, the via VA and the metal layer MT2 are formed in the trench TC2. As such, the semiconductor structure A-2 is formed through the FIGS. 26A to 26E.

[0300] In the embodiment shown in the FIGS. 26A to 26E, the blocking layer BK1 is used to block the forming of the barrier layer BR2, such that only the liner layer LN2 is disposed between the via VA and the self-forming metal capping layer CP1.

[0301] Please refer to FIGS. 27A to 27F, which illustrate a manufacturing method of the semiconductor structure A-3. As shown in the FIG. 27A, the trench TC2 is formed in the interlayer dielectric layer ILD2.

[0302] Next, as shown in the FIG. 27B, a blocking layer BK1 is formed on the self-forming metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0303] Then, as shown in the FIG. 27C, the barrier layer BR2 is formed on the interlayer dielectric layer ILD2 and the lateral wall of the trench TC2, and then the blocking layer BK1 is removed.

[0304] Afterwards, as shown in the FIG. 27D, a blocking layer BK2 is formed on the self-forming metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0305] Next, as shown in the FIG. 27E, the liner layer LN2 is formed on the barrier layer BR2, and then the blocking layer BK2 is removed.

[0306] Afterwards, as shown in the FIG. 27F, the via VA and the metal layer MT2 are formed in the trench TC2. As such, the semiconductor structure A-3 is formed through the FIGS. 27A to 27F.

[0307] In the embodiment shown in the FIGS. 27A to 27F, the blocking layer BK1 is used to block the forming of the barrier layer BR2 and the liner layer LN2, such that the barrier layer BR2 and the liner layer LN2 are not disposed between the via VA and the self-forming metal capping layer CP1.

[0308] Please refer to FIGS. 28A to 28M, which illustrate a manufacturing method of the semiconductor structure B-1. As shown in the FIG. 28A, the metal conductor MC1 with metal dopants dp1 is filled in the trench TC1 of the interlayer dielectric layer ILD1 and the planarization is performed on the metal conductor MC1 with the metal dopants dp1.

[0309] Next, as shown in the FIG. 28B, the thermal treatment, the photo treatment or the bias-assist treatment is performed on the metal conductor MC1 with the metal dopants dp1 to form the self-forming metal capping layer CP1 on the metal layer MT1.

[0310] Afterwards, as shown in the FIG. 28C, the etching stop bi-layer structure ESBS1 is formed on the interlayer dielectric layer ILD1 and the self-forming metal capping layer CP1, and the interlayer dielectric layer ILD21 is formed on the etching stop bi-layer structure ESBS1.

[0311] Then, as shown in the FIG. 28D, the trench TC2 is formed in the interlayer dielectric layer ILD21. The trench TC2 exposes the self-forming metal capping layer CP1.

[0312] Next, as shown in the FIG. 28E, the barrier layer BR21 and the liner layer LN21 are formed on the interlayer dielectric layer ILD21, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0313] Then, as shown in the FIG. 28F, a metal conductor MC2 with metal dopants dp2 is filled in the trench TC2 of the interlayer dielectric layer ILD21. In this step, the metal conductor MC2 with the metal dopants dp2 could be filled by, for example, Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP), Electroless plating, or other suitable processes. In this step, a process temperature is 10 C. to 400 C.

[0314] Next, as shown in the FIG. 28G, the planarization is performed on the metal conductor MC2 with the metal dopants dp2. In this step, the planarization could be performed by, for example, Chemical-Mechanical Planarization (CMP) or other suitable processes.

[0315] Afterwards, as shown in the FIG. 28H, a thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor MC2 with the metal dopants dp2 to form the self-forming metal capping layer CP2 on the via VA. In this step, the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants dp1 will be gathered at the top of the metal conductor MC2 to form the via VA and the self-forming metal capping layer CP2 disposed thereon. In this step, a process temperature is 10 C. to 400 C. The process temperature in the step shown in the FIG. 28F is lower than the process temperature in the step shown in the FIG. 28H.

[0316] Next, as shown in the FIG. 28I, the etching stop bi-layer structure ESBS2 is formed on the interlayer dielectric layer ILD21 and the self-forming metal capping layer CP2, and the interlayer dielectric layer ILD22 is formed on the etching stop bi-layer structure ESBS2. In this step, the interlayer dielectric layer ILD22 could be formed, for example, by spin coating, Plasma Enhanced Chemical Vapor Deposition (PECVD), Plasma Enhanced Atomic Layer Deposition (PEALD) or other suitable process.

[0317] Then, as shown in the FIG. 28J, a trench TC3 is formed in the interlayer dielectric layer ILD22. The trench TC3 exposes the self-forming metal capping layer CP2.

[0318] Next, as shown in the FIG. 28K, the barrier layer BR22 and the liner layer LN22 are formed on the interlayer dielectric layer ILD22, the bottom surface of the trench TC3 and the later-wall of the trench TC3.

[0319] Afterwards, as shown in the FIG. 28L, a metal conductor MT3 is filled in the trench TC3.

[0320] Then, as shown in the FIG. 28M, the planarization is performed on the metal conductor MC3. In this step, the planarization could be performed by, for example, Chemical-Mechanical Planarization (CMP) or other suitable processes. As such, the semiconductor structure B-1 is formed through the FIGS. 28A to 28M.

[0321] In the embodiment shown in the FIGS. 28A to 28M, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0322] Please refer to FIGS. 29A to 290, which illustrate a manufacturing method of the semiconductor structure B-9. As shown in the FIG. 29A, the trench TC2 is formed in the interlayer dielectric layer ILD21. The trench TC2 exposes the self-forming metal capping layer CP1.

[0323] Next, as shown in the FIG. 29B, the blocking layer BK1 is formed on the self-forming metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0324] Then, as shown in the FIG. 29C, the barrier layer BR21 is formed on the interlayer dielectric layer ILD21, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0325] Next, as shown in the FIG. 29D, the blocking layer BK2 is formed on the interlayer dielectric layer ILD21, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0326] Afterwards, as shown in the FIG. 29E, the liner layer LN21 is formed on the barrier layer BR21, and then the blocking layer BK2 is removed.

[0327] Then, as shown in the FIG. 29F, the metal conductor MC2 with the metal dopants dp2 is filled in the trench TC2 of the interlayer dielectric layer ILD21.

[0328] Next, as shown in the FIG. 29G, the planarization is performed on the metal conductor MC2 with the metal dopants dp2.

[0329] Afterwards, as shown in the FIG. 29H, the thermal treatment, the photo treatment or the bias-assist treatment is performed on the metal conductor MC2 with the metal dopants dp2 to form the self-forming metal capping layer CP2 on the via VA.

[0330] Next, as shown in the FIG. 29I, the etching stop bi-layer structure ESBS2 is formed on the interlayer dielectric layer ILD21 and the self-forming metal capping layer CP2, and the interlayer dielectric layer ILD22 is formed on the etching stop bi-layer structure ESBS2.

[0331] Then, as shown in the FIG. 29J, the trench TC3 is formed in the interlayer dielectric layer ILD22. The trench TC3 exposes the self-forming metal capping layer CP2.

[0332] Next, as shown in the FIG. 29K, a blocking layer BK3 is formed on the self-forming metal capping layer CP2.

[0333] Then, as shown in the FIG. 29L, the barrier layer BR22 is formed on the interlayer dielectric layer ILD22, the bottom surface of the trench TC3 and the later-wall of the trench TC3, and then the blocking layer BK3 is removed.

[0334] Afterwards, as shown in the FIG. 29M, a blocking layer BK4 is formed on the self-forming metal capping layer CP2.

[0335] Then, as shown in the FIG. 29N, the liner layer LN22 is formed on the barrier layer BR22, and then the blocking layer BK4 is removed.

[0336] Afterwards, as shown in the FIG. 29O, the metal conductor MC3 is filled in the trench TC3 to form the metal layer MT2. As such, the semiconductor structure B-9 is formed through the FIGS. 29A to 29O.

[0337] In the embodiment shown in the FIGS. 29A to 28O, the self-forming metal capping layer CP1 is self-formed on the metal layer MT1 without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD1 and the etching stop bi-layer structure ESBS1. The self-forming metal capping layer CP2 is self-formed on the via VA without any selective deposition process. Therefore, any metallic residue would not be formed on the interface between the interlayer dielectric layer ILD21 and the etching stop bi-layer structure ESBS2. The selectivity loss issue which caused by conventional metal-on-metal (MoM) selective deposition process for the metal cap would be avoided.

[0338] Please refer to FIGS. 30A to 30J, which illustrate a manufacturing method of the semiconductor structure C-1. As shown in the FIG. 30A, a metal conductor MC4 with metal dopants dp4 is filled in the trench TC1 of the interlayer dielectric (ILD) layer ILD1. In this step, the metal conductor MC4 with the metal dopants dp4 could be filled by, for example, Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP), Electroless plating, or other suitable processes. In this step, a process temperature is 10 C. to 400 C.

[0339] Next, as shown in the FIG. 30B, the metal capping layer CP1 is formed on the metal conductor MC4 with the metal dopants dp4. In this step, the metal capping layer CP1 is formed by selective deposition process.

[0340] Then, as shown in the FIG. 30C, a thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor MC4 with the metal dopants dp4 to form the self-aligned etching stop layer ESL1 and the first metal layer MT1. The self-aligned etching stop layer ESL1 is formed on the metal capping layer CP1. In this step, the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants dp3 will be gathered at the top of the metal capping layer CP1 to form the metal layer MT1 and the self-aligned etching stop layer ESL1. In this step, a process temperature is 10 C. to 400 C. The process temperature in the step shown in the FIG. 30C is lower than the process temperature in the step shown in the FIG. 30A.

[0341] Afterwards, as shown in the FIG. 30D, the hermetic layer HM1, the conformal etching stop layer ESL2, and the hermetic layer HM2 are formed on the interlayer dielectric layer ILD1 and the self-aligned etching stop layer ESL1 to form the etching stop bi-layer structure ESBS1.

[0342] Then, as shown in the FIG. 30E, the interlayer dielectric layer ILD2 is formed on the etching stop bi-layer structure ESBS1.

[0343] Next, as shown in the FIG. 30F, the trench TC2 is formed in the interlayer dielectric layer ILD2.

[0344] Afterwards, as shown in the FIG. 30G, the barrier layer BR2 is formed on the interlayer dielectric layer ILD2, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0345] Then, as shown in the FIG. 30H, the liner layer LN2 is formed on the barrier layer BR2.

[0346] Next, as shown in the FIG. 30I, the metal contact MC5 is filled in the trench TC2.

[0347] Then, as shown in the FIG. 30J, planarization is performed to form the via VA and the metal layer MT2. As such, the semiconductor structure C-1 is formed through the FIGS. 30A to 30J.

[0348] In the embodiment shown in the FIGS. 30A to 30J, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0349] Please refer to FIGS. 31A to 31F, which illustrate a manufacturing method of the semiconductor structure C-2. As shown in the FIG. 31A, the trench TC2 is formed in the interlayer dielectric layer ILD2.

[0350] Afterwards, as shown in the FIG. 31B, the blocking layer BK1 is formed on the metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0351] Then, as shown in the FIG. 31C, the barrier layer BR2 is formed on the interlayer dielectric layer ILD2, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0352] Afterwards, as shown in the FIG. 31D, the liner layer LN2 is formed on the barrier layer BR2.

[0353] Next, as shown in the FIG. 31E, the metal contact MC5 is filled in the trench TC2.

[0354] Then, as shown in the FIG. 31F, planarization is performed to form the via VA and the metal layer MT2. As such, the semiconductor structure C-2 is formed through the FIGS. 31A to 31F.

[0355] In the embodiment shown in the FIGS. 31A to 31G, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0356] Please refer to FIGS. 32A to 32G, which illustrate a manufacturing method of the semiconductor structure C-3. As shown in the FIG. 32A, the trench TC2 is formed in the interlayer dielectric layer ILD2.

[0357] Afterwards, as shown in the FIG. 32B, the blocking layer BK1 is formed on the metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0358] Then, as shown in the FIG. 32C, the barrier layer BR2 is formed on the interlayer dielectric layer ILD2, the bottom surface of the trench TC2 and the later-wall of the trench TC2, and then the blocking layer BK2 is removed.

[0359] Afterwards, as shown in the FIG. 32D, the blocking layer BK2 is formed on the metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0360] Then, as shown in the FIG. 32E, the liner layer LN2 is formed on the barrier layer BR2 and then the blocking layer BK2 is removed.

[0361] Next, as shown in the FIG. 32F, the metal contact MC5 is filled in the trench TC2.

[0362] Then, as shown in the FIG. 32G, planarization is performed to form the via VA and the metal layer MT2. As such, the semiconductor structure C-3 is formed through the FIGS. 32A to 32G.

[0363] In the embodiment shown in the FIGS. 32A to 32G, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process. Therefore, the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1.

[0364] Please refer to FIGS. 33A to 33P, which illustrate a manufacturing method of the semiconductor structure D-1. As shown in the FIG. 33A, the trench TC2 is formed in the interlayer dielectric layer ILD21.

[0365] Afterwards, as shown in the FIG. 33B, the barrier layer BR21 is formed on the interlayer dielectric layer ILD21, the bottom surface of the trench TC2 and the later-wall of the trench TC2.

[0366] Next, as shown in the FIG. 33C, the liner layer LN2 is formed on the barrier layer BR2.

[0367] Afterwards, as shown in the FIG. 33D, the metal contact MC5 with metal dopants dp5 is filled in the trench TC2. In this step, a process temperature is 10 C. to 400 C.

[0368] Then, as shown in the FIG. 33E, planarization is performed on the metal contact MC5 with the metal dopants dp5.

[0369] Next, as shown in the FIG. 33F, the metal capping layer CP2 is formed on the metal contact MC5 with the dopants dp5.

[0370] Then, as shown in the FIG. 33G, a thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor MC5 with the metal dopants dp5 to form the self-aligned etching stop layer ESL3 and the via VA. The self-aligned etching stop layer ESL3 is formed on the metal capping layer CP2. In this step, the thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage. After the thermal treatment, the photo treatment or the bias-assist treatment, the dopants dp5 will be gathered at the top of the metal capping layer CP2 to form the via VA and the self-aligned etching stop layer ESL3. In this step, a process temperature is 10 C. to 400 C. The process temperature in the step shown in the FIG. 33G is lower than the process temperature in the step shown in the FIG. 33D.

[0371] Afterwards, as shown in the FIG. 33H, the hermetic layer HM3, the conformal etching stop layer ESL4, and the hermetic layer HM4 are formed on the interlayer dielectric layer ILD21 and the self-aligned etching stop layer ESL3 to form the etching stop bi-layer structure ESBS2.

[0372] Then, as shown in the FIG. 33I, the interlayer dielectric layer ILD22 is formed on the etching stop bi-layer structure ESBS2.

[0373] Next, as shown in the FIG. 33J to FIG. 33K, the trench TC3 is formed in the interlayer dielectric layer ILD22. The etching is stopped at the self-aligned etching stop layer ESL3.

[0374] Afterwards, as shown in the FIG. 33L, the self-aligned etching stop layer ESL3 is removed and the metal capping layer CP2 is formed on the via VA.

[0375] Next, as shown in the FIG. 33M, the barrier layer BR22 is formed on the interlayer dielectric layer ILD22, the bottom surface of the trench TC3 and the later-wall of the trench TC3.

[0376] Then, as shown in the FIG. 33N, the liner layer LN22 is formed on the barrier layer BR22.

[0377] Next, as shown in the FIG. 33O, the metal contact MC6 is filled in the trench TC3.

[0378] Then, as shown in the FIG. 33P, planarization is performed to form the metal layer MT2. As such, the semiconductor structure D-1 is formed through the FIGS. 33A to 33P.

[0379] In the embodiment shown in the FIGS. 33A to 33P, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 (shown in FIG. 33G) formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 (shown in FIG. 33G) in the semiconductor structure D-1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3 (shown in FIG. 33G).

[0380] Please refer to FIGS. 34A to 34K, which illustrate a manufacturing method of the semiconductor structure D-3. As shown in the FIG. 34A, the trench TC2 is formed in the interlayer dielectric layer ILD21.

[0381] Afterwards, as shown in the FIG. 34B, the blocking layer BK1 is formed on the metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0382] Then, as shown in the FIG. 34C, the barrier layer BR21 is formed on the interlayer dielectric layer ILD21 and the later-wall of the trench TC2, and then the blocking layer BK1 is removed.

[0383] Next, as shown in the FIG. 34D, the blocking layer BK2 is formed on the metal capping layer CP1 and located at the bottom surface of the trench TC2.

[0384] Then, as shown in the FIG. 34E, the liner layer LN2 is formed on the barrier layer BR2.

[0385] Afterwards, as shown in the FIG. 34F, the via is formed in the trench TC2, the interlayer dielectric layer ILD22, the trench TC3 is formed in the interlayer dielectric layer ILD22, and the metal capping layer CP2 is formed on the via VA.

[0386] Then, as shown in the FIG. 34G, the blocking layer BK3 is formed on the metal capping layer CP2.

[0387] Next, as shown in the FIG. 34H, the barrier layer BR22 is formed on the interlayer dielectric layer ILD22, the bottom surface of the trench TC3 and the later-wall of the trench TC3, and then the blocking layer BK3 is removed.

[0388] Afterwards, as shown in the FIG. 34I, the blocking layer BK4 is formed on the metal capping layer CP2.

[0389] Then, as shown in the FIG. 34J, the liner layer LN22 is formed on the barrier layer BR22, and then the blocking layer BK4 is removed.

[0390] Afterwards, as shown in the FIG. 34K, the metal conductor MC6 is filled in the trench TC3 to form the metal layer MT2. As such, the semiconductor structure D-3 is formed through the FIGS. 34A to 34K.

[0391] In the embodiment shown in the FIGS. 34A to 34K, the self-aligned etching stop layer ESL1 is self-formed on the metal capping layer CP1 without any selective deposition process, so the self-aligned etching stop layer ESL1 is only disposed on the metal capping layer CP1. The self-aligned etching stop layer ESL3 formed on the via VA only is removed, so the there is no self-aligned etching stop layer ESL3 in the semiconductor structure D-1. The parasitic capacitance of the interconnection can be effectively decreased due to the reduction of the high-k material used for the self-aligned etching stop layer ESL1 or the self-aligned etching stop layer ESL3.

[0392] According to the disclosure described above, several embodiments are shown as below.

[0393] Example Embodiment 1: A manufacturing method of a semiconductor structure is provided. The manufacturing method includes the following steps. A trench is formed in a first interlayer dielectric (ILD) layer. A metal conductor with metal dopants is filled in the trench. Planarization is performed on the metal conductor with the metal dopants. A thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor with the metal dopants to form a self-forming metal capping layer on a first metal layer. An etching stop bi-layer structure is formed on the first interlayer dielectric layer and the self-forming metal capping layer. A via, a second interlayer dielectric (ILD) layer and a second metal layer are formed on the etching stop bi-layer structure. The via is embedded in the second interlayer dielectric layer and the via is disposed between the first metal layer and the second metal layer.

[0394] Example Embodiment 2 based on the Example Embodiment 1: A material of the metal dopants is Vanadium (V), Niobium (Nb), Molybdenum (Mo), Tungsten (W) or Manganese (Mn).

[0395] Example Embodiment 3 based on the Example Embodiment 1: In the step of filling the metal conductor with the metal dopants in the trench, the metal conductor with the metal dopants is filled by Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP) or Electroless plating.

[0396] Example Embodiment 4 based on the Example Embodiment 1: In the step of filling the metal conductor with the metal dopants in the trench, a process temperature is 10 C. to 400 C.

[0397] Example Embodiment 5 based on the Example Embodiment 1: The thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage.

[0398] Example Embodiment 6 based on the Example Embodiment 1: In the step of performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-forming metal capping layer on the first metal layer, a process temperature is 10 C. to 400 C.

[0399] Example Embodiment 7 based on the Example Embodiment 1: A process temperature in the step of filling the metal conductor with the metal dopants in the trench is lower than a process temperature in the step of performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-forming metal capping layer on the first metal layer.

[0400] Example Embodiment 8 based on the Example Embodiment 1: A thickness of the self-forming metal capping layer is 1 to 100 m.

[0401] Example Embodiment 9: A manufacturing method of a semiconductor structure is provided. The manufacturing method of the semiconductor structure include the following steps. A trench is formed in a first interlayer dielectric (ILD) layer. A metal conductor with metal dopants is filled in the trench. Planarization is performed on the metal conductor with the metal dopants. A metal capping layer is formed on the metal conductor with the metal dopants. A thermal treatment, a photo treatment or a bias-assist treatment is performed on the metal conductor with the metal dopants to form a self-aligned etching stop layer and a first metal layer. The self-aligned etching stop layer is formed on the metal capping layer. A conformal etching stop layer is formed on the first interlayer dielectric layer and the self-aligned etching stop layer to form an etching stop bi-layer structure. A via, a second interlayer dielectric (ILD) layer and a second metal layer are formed. The via is embedded in the second interlayer dielectric layer and the via is disposed between the first metal layer and the second metal layer.

[0402] Example Embodiment 10 based on the Example Embodiment 9: A material of the metal dopants is Zirconium (Zr) or Aluminum (Al).

[0403] Example Embodiment 11 based on the Example Embodiment 9: In the step of filling the metal conductor with the metal dopants in the trench, the metal conductor with the metal dopants is filled by Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Physical Vapor Deposition (PVD), Electro Chemical Plating (ECP) or Electroless plating.

[0404] Example Embodiment 12 based on the Example Embodiment 9: In the step of filling the metal conductor with the metal dopants in the trench, a process temperature is 10 C. to 400 C.

[0405] Example Embodiment 13 based on the Example Embodiment 9: The thermal treatment is performed by a hotplate, the photo treatment is performed by a laser, and the bias-assist treatment is performed by applying a voltage.

[0406] Example Embodiment 14 based on the Example Embodiment 9: A thickness of the self-aligned etching stop layer is 1 to 100 m.

[0407] Example Embodiment 15 based on the Example Embodiment 9: In the step of performing the thermal treatment, the photo treatment or the bias-assist treatment on the metal conductor with the metal dopants to form the self-aligned etching stop layer and the first metal layer, a process temperature is 10 C. to 400 C.

[0408] Example Embodiment 16: A semiconductor structure is provided. The semiconductor structure includes a first interlayer dielectric (ILD) layer, a first metal layer, a metal capping layer, an etching stop bi-layer structure, a second interlayer dielectric layer, a via and a second metal layer. The first metal layer is embedded in the first interlayer dielectric layer. The metal capping layer is disposed on the first metal layer. The etching stop bi-layer structure includes a self-aligned etching stop layer and a conformal etching stop layer. The self-aligned etching stop layer is disposed on the metal capping layer. The conformal etching stop layer is disposed on the first interlayer dielectric layer and the self-aligned etching stop layer. The second interlayer dielectric (ILD) layer is disposed on the etching stop bi-layer structure. The via is embedded in the second interlayer dielectric layer. The second metal layer is embedded in the second interlayer dielectric layer and disposed on the via.

[0409] Example Embodiment 17 based on the Example Embodiment 16: A material of the self-aligned etching stop layer is Zirconium oxide (ZrO2) or Aluminum oxide (Al).

[0410] Example Embodiment 18 based on the Example Embodiment 16: A thickness of the self-aligned etching stop layer is 1 to 100 m.

[0411] Example Embodiment 19 based on the Example Embodiment 16: The self-aligned etching stop layer only covers the metal capping layer.

[0412] Example Embodiment 20 based on the Example Embodiment 16: The etching stop bi-layer structure further includes a first hermetic layer and a second hermetic layer. The first hermetic layer is disposed between the first interlayer dielectric layer and the conformal etching stop layer, and disposed between the self-aligned etching stop layer and the conformal etching stop layer. The second hermetic layer is disposed on the conformal etching stop layer.

[0413] The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.