Method for manufacturing semiconductor device
11557661 · 2023-01-17
Assignee
Inventors
Cpc classification
H01L29/6681
ELECTRICITY
H01L21/76897
ELECTRICITY
H01L21/3086
ELECTRICITY
H01L29/517
ELECTRICITY
H01L29/511
ELECTRICITY
H01L29/785
ELECTRICITY
H01L29/66795
ELECTRICITY
International classification
H01L21/28
ELECTRICITY
H01L29/66
ELECTRICITY
Abstract
A method for manufacturing a semiconductor device includes: a first insulating film forming step of forming a first insulating film in a transistor having a structure in which a source and a drain raised in a fin shape are covered with a gate; a sacrifice film forming step of forming a sacrifice film; a hard mask pattern forming step of forming a hard mask film having a desired pattern; a first opening forming step of forming a first opening; a second insulating film forming step of forming a second insulating film made of a material different from the first insulating film, in the first opening; a second opening forming step of forming a second opening by removing the sacrifice film, after the second insulating film forming step; and a contact plug forming step of forming a contact plug in the second opening.
Claims
1. A method for manufacturing a semiconductor device, the method comprising: a first insulating film forming step of forming a first insulating film to cover at least a part of a surface of a gate in a transistor having a structure in which a source and a drain raised in a fin shape are covered with the gate; a sacrifice film forming step of forming a sacrifice film on the first insulating film; a hard mask film forming step of forming a hard mask film on the sacrifice film; a cut mask forming step of forming a cut mask on the hard mask film; a hard mask pattern forming step of forming a hard mask film having a desired pattern on the sacrifice film by using the cut mask as an etching mask; a first opening forming step of forming a first opening by removing a part of the sacrifice film by using the hard mask film as an etching mask; a second insulating film forming step of forming a second insulating film made of a material different from the first insulating film, in the first opening; a second opening forming step of forming a second opening by removing the sacrifice film, at a position where at least a part of the source or the drain is electrically connected to a wiring layer, after the second insulating film forming step; and a contact plug forming step of forming a contact plug in the second opening, wherein the desired pattern is formed by removing the hard mask film at a position where the contact plug is not formed, and includes a plurality of hard mask patterns formed by a single cut mask.
2. The method of claim 1, wherein the hard mask pattern forming step includes: a step of forming the hard mask film with a line-and-space pattern on the sacrifice film; and a step of forming the desired pattern by cutting out a part of a line pattern of the line-and-space pattern.
3. The method of claim 1, further comprising: a hard mask film removing step of removing the hard mask film after the second insulating film forming step and before the second opening forming step.
4. The method of claim 1, wherein the hard mask film is a film having a high etching selectivity with respect to the sacrifice film.
5. The method of claim 1, wherein the first insulating film is a SiN film.
6. The method of claim 5, wherein the sacrifice film is an SOC film, the second insulating film is an SOD film or a SiO.sub.2 film, and in the second opening forming step, the sacrifice film is removed by ashing.
7. The method of claim 5, wherein the sacrifice film is an a-Si film, the second insulating film is an SOD film or a SiO.sub.2 film, and in the second opening forming step, the sacrifice film is removed by dry etching using a gas containing chlorine or bromine.
8. The method of claim 5, wherein the sacrifice film is an SOD film, the second insulating film is a SiO.sub.2 film, and in the second opening forming step, the sacrifice film is removed by wet etching.
9. The method of claim 1, wherein the hard mask pattern forming step further comprises a removing step of removing only a part of the hard mask film by using the cut mask as an etching mask.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
(24) In the method of Japanese Patent Laid-open Publication No. 2014-531770, when the opening is formed by high selectivity ratio etching, a part of the insulating film covering the gate may be etched in some cases. When a part of the insulating film covering the gate is etched in this manner, since a distance between wirings in the contact plug formed in the opened portion and the gate is shortened, an increase of a leakage current or a short circuit occurs between wirings in the contact plug and the gate.
(25) Thus, there is a demand for a manufacturing method of a semiconductor device, by which it is possible to suppress a leakage current or a short circuit.
(26) According to the disclosed method for manufacturing a semiconductor device, a leakage current or a short circuit may be suppressed.
(27) Hereinafter, modes for carrying out the present invention will be described with reference to drawings. Meanwhile, in the present specification and drawings, substantially the same components will be denoted by the same reference numerals and redundant descriptions thereof will be omitted.
(28) Hereinafter, a case where as a semiconductor device, a FinFET is manufactured having a structure in which a source and a drain raised in a fin shape are covered with a gate from left, right, and top (three) directions will be described as an example, but the present disclosure is not limited to such a mode. The semiconductor device may be, for example, a FinFET having a structure in which a source and a drain raised in a fin shape are covered with a gate from left and right (two) directions.
(29) In a method of manufacturing a semiconductor device of the present embodiment, first, a sacrifice film is formed at a position where a contact plug that electrically connects a source and a drain raised in a fin shape to a wiring layer is to be formed, and an insulating film made of a material different from the sacrifice film is formed at a position where the contact plug is not to be formed. Then, in a state where the insulating film is caused to remain, the sacrifice film is removed, and the contact plug is formed in a portion from which the sacrifice film is removed. Accordingly, a FinFET in which a desired source and a drain (hereinafter, also referred to as a “source/drain region”) are electrically connected to a wiring layer via a contact plug may be manufactured, and a leakage current or a short circuit may be suppressed. The reason the leakage current or the short circuit may be suppressed will be described below.
(30) Hereinafter, a method of manufacturing a semiconductor device of the present embodiment will be described in detail.
(31) As illustrated in
(32) First, as illustrated in
(33) The first insulating film 106 is an insulating film that prevents the gate 102 from being etched when an opening for a contact plug 120 electrically connecting a source/drain region to a wiring layer is formed, and is a contact etch stop layer (CESL). It is desirable that the first insulating film 106 is, for example, a silicon nitride film (SiN film). Meanwhile, the contact plug 120 will be described below.
(34) A method of forming the first insulating film 106 is not particularly limited, but may be arbitrarily selected according to, for example, a material or a film thickness of a film to be formed. When the first insulating film 106 is a SiN film, for example, chemical vapor deposition (CVD) may be used. Atomic layer deposition (ALD) or molecular layer deposition (MDL) may also be used.
(35) Next, as illustrated in
(36) The sacrifice film 108 is a film that will be removed in the second opening forming step S70 to be described below, and is, for example, a dummy plug. The sacrifice film 108 is a film made of a material different from the first insulating film 106 and is desirably a film having a high etching selectivity with respect to the first insulating film 106 and a second insulating film to be described below. When the first insulating film 106 is a SiN film, for example, an SOC (spin on carbon) film, an amorphous silicon (a-Si) film, or an SOD (spin on dielectric) film may be used. Among them, from the viewpoint that there is a high etching selectivity particularly with respect to a SiN film, an SOC film is desirable.
(37) After the sacrifice film 108 is formed, a flattening processing of flattening the top surface of the sacrifice film 108 may be performed. The method of the flattening processing is not particularly limited. However, when the sacrifice film 108 is an SOC film, for example, a method of irradiating the sacrifice film 108 with ultraviolet rays (UV) may be used. After the flattening processing, the sacrifice film 108 may be further formed on the flattened top surface of the sacrifice film 108.
(38) Next, as illustrated in
(39) Specifically, a protective film 110 formed of, for example, a SiN film is formed on the sacrifice film 108 formed in the sacrifice film forming step S20, and a hard mask pattern 112a, in which the hard mask film 112 is removed at a position where the contact plug 120 is not to be formed, is formed on the protective film 110. That is, since the hard mask pattern 112a is formed in which the hard mask film 112 is caused to remain at a position where the contact plug 120 to be described below is to be formed, the hard mask pattern 112a may be formed through a so-called one-dimensional (1D) layout in which after a line-and-space pattern (L&S pattern) is formed, a part of the line pattern is cut out. Thus, a margin of an edge placement error (EPE) increases. Meanwhile, details of a method of forming a desired pattern on the hard mask film 112 will be described below.
(40) Next, as illustrated in
(41) A method of removing the sacrifice film 108 is not particularly limited, and may be arbitrarily selected according to, for example, a material of a film to be removed. However, it is desirable to use, for example, reactive ion etching (RIE).
(42) Next, as illustrated in
(43) The second insulating film 116 is an insulating film formed above the source/drain region and is, for example, a PMD film. The second insulating film 116 is a film made of a material different from the first insulating film 106 and the sacrifice film 108, and is desirably a film having a high etching selectivity with respect to the sacrifice film 108. When the sacrifice film 108 is an SOC film, for example, an SOD film or a silicon oxide film (SiO.sub.2 film) is desirable. When the sacrifice film 108 is an a-Si film, for example, an SOD film or a SiO.sub.2 film is desirable. When the sacrifice film 108 is an SOD film, for example, a SiO.sub.2 film is desirable.
(44) Next, as illustrated in
(45) A method of removing the hard mask film 112 is not particularly limited but, for example, chemical mechanical polishing (CMP), dry etching, or wet etching may be used. Specifically, the second insulating film 116 and the hard mask film 112 may be removed by performing polishing by, for example, CMP until the top surface of the sacrifice film 108 is exposed. After polishing by CMP is performed until the top surface of the hard mask film 112 is exposed, the hard mask film 112 may be removed by, for example, dry etching or wet etching. In the case where it is possible to remove the hard mask film 112 simultaneously with removal of the sacrifice film 108 in the second opening forming step S70 to be described below, the hard mask film removing step S60 may not be performed prior to the second opening forming step S70 and the hard mask film removing step S60 may be omitted.
(46) Next, as illustrated in
(47) A method of removing the sacrifice film 108 is not particularly limited, and may be arbitrarily selected according to, for example, materials of the sacrifice film 108 and the second insulating film 116.
(48) In the case where the sacrifice film 108 is an SOC film, the first insulating film 106 is a SiN film, and the second insulating film 116 is an SOD film or a SiO.sub.2 film, it is desirable to use, for example, ashing. When the SOC film is removed by ashing, since the SOC film has a high etching selectivity with respect to the SiN film, the SOD film and the SiO.sub.2 film, the SiN film, the SOD film and the SiO.sub.2 film are hardly shaved. That is, the first insulating film 106 and the cap dielectric film 104 are hardly shaved and the shapes may be maintained.
(49) In the case where the sacrifice film 108 is an a-Si film, the first insulating film 106 is a SiN film, and the second insulating film 116 is an SOD film or a SiO.sub.2 film, it is desirable to use, for example, dry etching using a gas containing chlorine or bromine. When the a-Si film is removed by dry etching using a gas containing chlorine or bromine, since the a-Si film has a high etching selectivity with respect to the SiN film, the SOD film and the SiO.sub.2 film, the SiN film, the SOD film, and the SiO.sub.2 film are hardly shaved. That is, the first insulating film 106 and the cap dielectric film 104 are hardly shaved and the shapes may be maintained.
(50) In the case where the sacrifice film 108 is an SOD film, the first insulating film 106 is a SiN film, and the second insulating film 116 is a SiO.sub.2 film, it is desirable to use, for example, wet etching. When the SOD film is removed by wet etching, since the SOD film has a high etching selectivity with respect to the SiN film and the SiO.sub.2 film, the SiN film and the SiO.sub.2 film are hardly shaped. That is, the first insulating film 106 and the cap dielectric film 104 are hardly shaved, and the shapes may be maintained.
(51) Next, as illustrated in
(52) A method of removing the first insulating film 106 is not particularly limited, but it is desirable to use, for example, RIE. Although the first insulating film 106 and the cap dielectric film 104 on the top portion of the gate 102 are also partially shaved when the source/drain region is exposed at the bottom portion in the second opening 118, since the shapes of the first insulating film 106 and the cap dielectric film 104 are maintained in a step of forming the second opening 118 (the second opening forming step S70), a final shaving amount may be controlled. Accordingly, since a distance between wirings in the second opening 118 and the gate 102 is maintained, a leakage current or a short circuit may be suppressed between wirings in the contact plug 120 and the gate 102.
(53) Next, as illustrated in
(54) The contact plug 120 is a film that electrically connects the source/drain region to the wiring layer, and is, for example, a conductive film. The conductive film is not particularly limited but it is desirable to use, for example, tungsten (W), copper (Cu), or polysilicon (Poly-Si).
(55) A method of forming the contact plug 120 is not particularly limited, but may be arbitrarily selected according to, for example, a material of a conductive film. After a barrier metal film, such as, for example, a stacked film of a titanium nitride film (TiN film) and a titanium film (Ti film) is formed in the second opening 118, the contact plug 120 may be formed.
(56) Through the above-described steps, a FinFET in which the desired source/drain region is electrically connected to the wiring layer may be manufactured.
(57) Next, a method of forming a desired pattern on the hard mask film 112 [the hard mask pattern forming step S30] will be described.
(58) As illustrated in
(59) First, as illustrated in
(60) The hard mask film 112 only has to be a film that functions as an etching mask when the sacrifice film 108 is etched in the first opening forming step S40. When the sacrifice film 108 is an SOC film, a film such as, for example, a stacked film of a SiO.sub.2 film and a SiN film, or a stacked film of a SiO.sub.2 film and a TiN film, which has a high etching selectivity with respect to the SOC film, is desirable. When the sacrifice film 108 is an SOD film, a film such as, for example, a silicon film (Si film) or a TiN film, which has a high etching selectivity with respect to the SOD film, is desirable.
(61) A method of forming the hard mask film 112 is not particularly limited, but may be arbitrarily selected according to, for example, a material or a film thickness of a film to be formed.
(62) Next, as illustrated in
(63) Specifically, the hard mask film 112 is patterned such that a position corresponding to the source/drain region becomes a line pattern 112l, and a position corresponding to the gate 102 becomes a space pattern 112s.
(64) A method of patterning the hard mask film 112 is not particularly limited, but it is possible to use, for example, a method of forming a resist pattern on the hard mask film 112, and etching the hard mask film 112 by using the resist pattern as an etching mask. The resist pattern is formed by, for example, photolithography such that a position corresponding to the source/drain region becomes a line pattern, and a position corresponding to the gate 102 becomes a space pattern. Meanwhile, when a pattern finer than the resolution limit of an exposure device is formed, the L&S pattern may be formed on the hard mask film 112 by self-aligned multiple patterning (SAMP).
(65) Next, as illustrated in
(66) Specifically, in the line pattern 112l of the hard mask film 112, a line pattern at a position where the contact plug 120 electrically connecting the source/drain region to the wiring layer is not to be formed is removed so that a part of the line pattern of the hard mask film 112 is cut out.
(67) A method of cutting out a part of the line pattern is not particularly limited but it is possible to use a method of forming a cut mask on the hard mask film 112 by photolithography and etching the hard mask film 112 by using the cut mask as an etching mask. The cut mask is formed such that a position corresponding to a region to be cut out in the line pattern 112l becomes an open pattern.
(68) In the line pattern cutting-out step S33, when a pattern finer than, for example, the resolution limit of the exposure device is formed, a plurality of cut masks may be used. That is, the hard mask film 112 having the desired pattern is formed by using the plurality of cut masks. Specifically, as illustrated in
(69) Meanwhile, in
(70) Through the above-described steps, the hard mask film 112 having the desired pattern may be formed.
(71) Next, descriptions will be made on operations and effects in the case where after the L&S pattern is formed, a part of the line pattern 112l is cut out, thereby forming the hard mask film 112 having the desired pattern, with reference to
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(73) In the present embodiment, as described above, the hard mask film 112 is patterned such that the hard mask film 112 is removed at a position where the contact plug 120 is not to be formed and the hard mask film 112 is caused to remain at a position where the contact plug 120 is to be formed.
(74) Specifically, as illustrated in
(75) However, there is a case where due to an influence of accuracy in positioning (alignment), the position of the etching mask used in each step such as step LE1, step LE2 and step LE3 is shifted. However, in the manufacturing method of the semiconductor device of the present embodiment, even when the position of the etching mask used in each step such as step LE1, step LE2 and step LE3 is shifted in the X direction, since as illustrated in
(76) In contrast, conventionally, the hard mask film 112 is patterned such that the hard mask film 112 is removed at a position where the contact plug 120 is to be formed, and the hard mask film 112 is caused to remain at a position where the contact plug 120 is not to be formed.
(77) Specifically, as illustrated in
(78) Thus, in a conventional method, when the position of the etching mask used in each step such as step LE1, step LE2 and step LE3 is shifted in the X direction due to an influence of alignment accuracy, since as illustrated in
(79) As described above, in the manufacturing method of the semiconductor device of the present embodiment, the sacrifice film 108 is formed at a position where the contact plug 120 that electrically connects the source and the drain raised in a fin shape to the wiring layer is to be formed, and the second insulating film 116 made of a material different from the sacrifice film 108 is formed at a position where the contact plug 120 is not to be formed. Then, in a state where the second insulating film 116 is caused to remain, the sacrifice film 108 is removed, and the contact plug 120 is formed in a portion from which the sacrifice film 108 is removed. Accordingly, a FinFET in which a desired source/drain region is electrically connected to a wiring layer may be manufactured, and a leakage current or a short circuit may be suppressed.
(80) In the manufacturing method of the semiconductor device of the present embodiment, in the hard mask pattern forming step S30, the hard mask pattern 112a is formed in which the hard mask film 112 is removed at a position where the contact plug 120 is not to be formed. Thus, when the hard mask film 112 having the desired pattern is formed, the hard mask film 112 may be patterned through, for example, a so-called 1D layout in which an L&S pattern is formed, and a part of the line pattern is cut out. As a result, an EPE margin increases.
(81) Although as described above, the method for manufacturing a semiconductor device has been described through the above embodiments, the present disclosure is not limited to the above embodiments, and various modifications and improvements are possible within the scope of the present disclosure.
(82) This application claims the benefit of priority from the basic application No. 2016-059716, filed on Mar. 24, 2016 to the Japan Patent Office, the entire contents of which are incorporated herein by reference.
(83) TABLE-US-00001 Description of Symbols 102: gate 104: cap dielectric film 106: first insulating film 108: sacrifice film 110: protective film 112: hard mask film 112a: hard mask pattern 112l: line pattern 112s: space pattern 114: first opening 116: second insulating film 118: second opening 120: contact plug 152: etching mask 154: first cut mask 156: second cut mask