Semiconductor structure and forming method thereof

Abstract

The invention provides a semiconductor structure, the semiconductor structure includes a substrate, a gate structure which extends along a first direction, and a plurality of supporting patterns which are separated from each other and arranged along a second direction which is perpendicular to the first direction.

Claims

1. A semiconductor structure, comprising: a substrate; a gate structure located on the substrate and extending along a first direction; and a plurality of supporting patterns located in the gate structure, wherein the plurality of supporting patterns are separated from each other and arranged along a second direction, wherein the second direction is perpendicular to the first direction.

2. The semiconductor structure according to claim 1, further comprising a source and the drain, which are located on both sides of the gate structure.

3. The semiconductor structure according to claim 2, wherein the connection between the source and the drain is parallel to the second direction.

4. The semiconductor structure according to claim 1, wherein the plurality of supporting patterns constitute a plurality of supporting pattern dashed lines, wherein each supporting pattern dashed line extends along the second direction.

5. The semiconductor structure according to claim 1, wherein the material of the supporting pattern comprises silicon oxide.

6. The semiconductor structure according to claim 1, wherein the gate structure is made of high dielectric constant metal.

7. A method for forming a semiconductor structure, comprising: providing a substrate; forming a gate structure on the substrate and extending along a first direction; and forming a plurality of supporting patterns in the gate structure, wherein the plurality of supporting patterns are separated from each other and arranged along a second direction, wherein the second direction is perpendicular to the first direction.

8. The method according to claim 7, wherein the method for forming the supporting pattern in the gate structure comprising: forming a sacrificial gate on the substrate; performing an etching step on the sacrificial gate to form a plurality of holes in the sacrificial gate; filling an insulating layer beside the sacrificial gate and filling the holes; performing a planarization step to remove part of the insulating layer and expose the surface of the sacrificial gate; removing the sacrificial gate layer, leaving the insulating layers and defining a gate recess; and forming a high dielectric constant metal layer in the gate recess.

9. The method according to claim 7, further comprising forming a source and a drain, which are located on both sides of the gate structure.

10. The method according to claim 9, wherein the connection between the source and the drain is parallel to the second direction.

11. The method according to claim 7, wherein the plurality of supporting patterns constitute a plurality of supporting pattern dashed lines, wherein each supporting pattern dashed line extends along the second direction.

12. The method according to claim 7, wherein the material of the supporting pattern comprises silicon oxide.

13. The method according to claim 7, wherein the material of the gate structure comprises high dielectric constant metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 to FIG. 2 show a top view of a semiconductor structure according to an embodiment of the present invention.

[0009] FIG. 3 to FIG. 4 are schematic top views of a semiconductor structure according to another embodiment of the present invention.

DETAILED DESCRIPTION

[0010] To provide a better understanding of the present invention to users skilled in the technology of the present invention, preferred embodiments are detailed as follows. The preferred embodiments of the present invention are illustrated in the accompanying drawings with numbered elements to clarify the contents and the effects to be achieved.

[0011] Please note that the figures are only for illustration and the figures may not be to scale. The scale may be further modified according to different design considerations. When referring to the words “up” or “down” that describe the relationship between components in the text, it is well known in the art and should be clearly understood that these words refer to relative positions that can be inverted to obtain a similar structure, and these structures should therefore not be precluded from the scope of the claims in the present invention.

[0012] FIG. 1 to FIG. 2 show a top view of a semiconductor structure according to an embodiment of the present invention. As shown in FIG. 1, first, a substrate 10, such as a silicon substrate, is provided, and a sacrificial gate 12 (or a gate G) is formed on the substrate 10. The sacrificial gate 12 is made of polysilicon, for example. In the following steps, source/drain regions and dielectric layers (not shown) are formed on both sides of the sacrificial gate 12, and then a planarization step and an etching step are sequentially performed, and the sacrificial gate 12 is removed and replaced with a gate made of other materials such as metal. Details will be described in the following paragraphs.

[0013] After the sacrificial gate 12 is completed, as shown in FIG. 2, a source S and a drain D are defined on both sides of the sacrificial gate 12 by ion implantation. A first direction D1 and a second direction D2 are defined here, the first direction D1 is parallel to the extending direction of the sacrificial gate 12, and the second direction D2 is perpendicular to the first direction, and the gate the source S and the drain D here can form a transistor, wherein the current direction I of the transistor flows from the source S to the drain D, and the second direction D2 is parallel to the current direction I.

[0014] In a subsequent step, a dielectric layer (not shown) is formed around the sacrificial gate 12 to cover the sacrificial gate 12, and then a planarization step (such as chemical mechanical polishing, CMP) is performed to remove the redundant dielectric layer, so that the top surface of the dielectric layer is flush with the top surface of the sacrificial gate 12, and the top surface of the sacrificial gate 12 is exposed. Then, an etching step is performed to remove the sacrificial gate 12 and fill in other material layers (such as a high-k metal layer) to form a new metal gate (not shown) at the original sacrificial gate 12. However, in the above planarization step, the top surface of the gate may have a dishing phenomenon as described in the prior art. Therefore, in order to avoid such a problem, the present invention further includes forming a plurality of supporting patterns 14 in the sacrificial gate 12 after the sacrificial gate 12 is completed. The material of the supporting pattern 14 is an insulating material such as silicon oxide. The method for forming the supporting pattern 14 includes, for example, performing a patterning etching step after the sacrificial gate 12 is completed to form some recesses (corresponding to the shape of the final supporting pattern) in the sacrificial gate, and filling the recesses while filling a dielectric layer around the sacrificial gate 12, so that a dielectric layer (not shown) around the sacrificial gate 12 and the supporting pattern 14 in the sacrificial gate 12 can be formed at the same time.

[0015] In this embodiment, the supporting pattern 14 has a grid-like shape, that is, the supporting pattern 14 includes a plurality of lines, some of which extend along the first direction D1, and the other extends along the second direction D2. However, the applicant's experimental results show that although the formation of the supporting pattern 14 can reduce the probability of the dishing phenomenon, if the supporting pattern 14 contains a line pattern parallel to the first direction D1 (i.e., perpendicular to the current direction I), the current transmission effect in the gate will be hindered. In other words, this will significantly reduce the current conduction performance of the gate, which is not conducive to the electrical performance of the gate.

[0016] FIG. 3 to FIG. 4 are schematic top views of a semiconductor structure according to another embodiment of the present invention. In order to further improve the above problems, in another embodiment of the present invention, as shown in FIG. 3 and FIG. 4, the shape of the supporting pattern is changed in this embodiment, and the original supporting pattern 14 is replaced by the supporting pattern 14A. The main difference between the supporting pattern 14A and the supporting pattern 14 is that the pattern arranged by the supporting pattern 14A does not block the current direction I. More specifically, the supporting pattern 14A constitutes a plurality of supporting pattern dashed lines 15 arranged along the second direction D2, and the gap between the adjacent supporting pattern dashed lines 15 still leaves the gate material, and the supporting pattern 14A is not formed between the gap. Therefore, the plurality of supporting patterns 14A do not block the path (current direction I) through which the main current of the transistor flows. Therefore, compared with the above embodiments, even if the supporting pattern 14A is formed inside the gate in this embodiment, it has less influence on the electrical properties of the gate.

[0017] Then, as shown in FIG. 4, the sacrificial gate 12 is removed by an etching step (not shown), and each supporting pattern 14A is left, and then a metal layer, such as a high-k metal (high dielectric constant metal) layer, is refilled into the recess of the original sacrificial gate 12 to form a metal gate 16. The above steps are also called replacement metal gate (RMG) process, which belongs to the conventional technology in the field and will not be described in detail here. In addition, after the metal gate 16 is completed, a plurality of contact structures 18 can be formed on the metal gate 12 and the source S/drain D, and the contact structures 18 can electrically connect the transistor with other electronic devices. The manufacturing process of the contact structures 18 is also a conventional technology in the field, and will not be described in detail here.

[0018] According to the above description and drawings, the present invention provides a semiconductor structure, which comprises a substrate 10, a metal gate 16 extending along a first direction D1, and a plurality of supporting patterns 14A in the metal gate 16, wherein the plurality of supporting patterns 14A are separated from each other and arranged along a second direction D2, wherein the second direction D2 is perpendicular to the first direction D1.

[0019] In some embodiments of the present invention, a source S and a drain D are further included, which are located on both sides of the metal gate 16.

[0020] In some embodiments of the present invention, the connection between the source S and the drain D is parallel to the second direction D2.

[0021] In some embodiments of the present invention, a plurality of supporting patterns 14A constitute a plurality of supporting pattern dashed lines 15, wherein each supporting pattern dashed line 15 extends along the second direction D2.

[0022] In some embodiments of the present invention, the material of the supporting pattern 14A includes silicon oxide.

[0023] In some embodiments of the present invention, the metal gate 16 is made of high dielectric constant metal.

[0024] The present invention also provides a method for forming a semiconductor structure, which includes providing a substrate 10, forming a metal gate 16 extending along a first direction D1 on the substrate 10, and forming a plurality of supporting patterns 14A in the metal gate 16, wherein the plurality of supporting patterns 14A are separated from each other and arranged along a second direction D2, wherein the second direction D2 is perpendicular to the first direction.

[0025] In some embodiments of the present invention, the method for forming the supporting pattern 14A in the metal gate 16 includes forming a sacrificial gate 12 on the substrate 10, performing an etching step on the sacrificial gate 12 to form a plurality of holes in the sacrificial gate 12, filling an insulating layer beside the sacrificial gate and filling in the holes, performing a planarization step to remove part of the insulating layer, exposing the surface of the sacrificial gate 12, removing the sacrificial gate layer, leaving the insulating layers, defining a gate recess, and forming a high dielectric constant metal layer in the gate recess.

[0026] The invention is characterized in that a plurality of supporting patterns are formed in the gate to avoid the problem that the top of the gate is sunken when the gate is planarized. In addition, the arrangement direction of the supporting patterns in the present invention is parallel to the current direction (i.e., the direction from source to drain), so that the current flow path is less hindered, and the performance of the gate is better.

[0027] Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.