Semiconductor device and method for producing same

Abstract

Provided are: a semiconductor device in which planarization by means of a contact plug is easy and coverage of a barrier metal at a corner part of an insulating film is good; and a method for producing the semiconductor device.　A semiconductor device 1 has: a semiconductor layer 2; a silicide layer 3 provided on the semiconductor layer 2; a first insulation film 4 provided on the semiconductor layer 2 and having an opening 4A; a second insulation film 5 provided on a side wall of the opening 4A; a barrier metal 6 provided on the first insulation film 4, a corner part 8 of the second insulation film 5, a side wall of the second insulation film 5, and a silicide layer 3; and a contact plug 7 that fills a hole formed in the barrier metal 6 due to the opening 4A, wherein the corner part 8 of the second insulation film 5 has a rounded shape.

Description

Semiconductor device and manufacturing method thereof

[0001] The present invention relates to a semiconductor device and a manufacturing method thereof.

[0002] 2. Description of the Related Art A technique for connecting an upper electrode and a semiconductor layer via a contact hole while planarizing the upper surface side of a semiconductor device is to use a contact plug.

[0003] For example, FIGS. 8 and 9 of Patent Document 1 describe a technology in which a contact hole is formed in an interlayer insulating film provided on a semiconductor substrate (semiconductor layer) by photolithography and etching, a barrier metal is then formed inside and outside the contact hole, a silicide is then formed by heat treatment using RTA (Rapid Thermal Anneal), and then a contact plug is formed.

[0004] Japanese Patent Application Laid-Open No. 2016-225512

[0005] 12 and 13 are cross-sectional views illustrating the problems in the conventional method for manufacturing a semiconductor device.

[0006] As shown in FIG. 12 , the semiconductor device 1 includes a semiconductor layer 2, a silicide layer 3, a first insulating film 4, an opening 4A (contact hole) provided in the first insulating film 4, a barrier metal 6 composed of a laminated film of a first barrier metal 6A and a second barrier metal 6B, and a contact plug 7.

[0007] When the metal film for forming contact plug 7 is deposited by, for example, CVD (Chemical Vapor Deposition), the possibility of foreign matter being mixed in increases as the film thickness increases, so the metal film for forming contact plug 7 cannot be deposited to a very large thickness. Therefore, as shown in FIG. 12 , if the diameter of opening 4A is large, there is a problem that the inside of opening 4A may not be sufficiently flattened.

[0008] Furthermore, as shown in FIG. 13 , when an opening 4A is formed in the first insulating film 4 by photolithography and etching, the corner portions 8 of the first insulating film 4 have an angular shape, which results in poor coverage of the barrier metal 6 formed thereon, and there is a problem that peeling of the barrier metal 6 may occur at the corner portions 8.

[0009] The problem to be solved by the present invention is to provide a semiconductor device that can be easily planarized by contact plugs and has good coverage of the barrier metal at the corners of the insulating film, and a method for manufacturing the same.

[0010] In order to solve the above-mentioned problems, the semiconductor device of the present invention comprises a semiconductor layer, a silicide layer provided on the semiconductor layer, a first insulating film provided on the semiconductor layer and having an opening, a second insulating film provided on a sidewall of the opening, a barrier metal provided on the first insulating film, on a corner portion of the second insulating film, on a sidewall of the second insulating film, and on the silicide layer, and a contact plug that fills a hole generated in the barrier metal due to the opening, and the corner portion of the second insulating film has a rounded shape.

[0011] Furthermore, a method for manufacturing a semiconductor device according to the present invention is characterized by comprising: an opening formation step of forming an opening in a first insulating film formed on a semiconductor layer by photolithography and etching; a second insulating film formation step of depositing a second insulating film on the first insulating film and inside the opening, and forming the second insulating film on a sidewall of the opening by etching back, the second insulating film having rounded corners; a barrier metal formation step of depositing a barrier metal on the first insulating film, the corners of the second insulating film, the sidewalls of the second insulating film, and on the semiconductor layer inside the opening; a contact plug formation step of forming a contact plug to fill a hole generated in the barrier metal due to the opening; and a silicide layer formation step of forming a silicide layer in at least a part of the semiconductor layer inside the opening after the opening formation step and before the contact plug formation step.

[0012] According to the present invention, it is possible to realize a semiconductor device and a method for manufacturing the same in which planarization by contact plugs is easy and the coverage of the barrier metal at the corners of the insulating film is good.

[0013] 1 is a cross-sectional view of a semiconductor device according to a first embodiment. FIG. 2 is a flowchart illustrating a method for manufacturing a semiconductor device according to a first embodiment. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment. FIG. 4 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment. FIG. 5 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment. FIG. 6 is a cross-sectional view of a semiconductor device according to a second embodiment. FIG. 7 is a flowchart illustrating a method for manufacturing a semiconductor device according to a second embodiment. FIG. 8 is a cross-sectional view illustrating a problem in a conventional method for manufacturing a semiconductor device. FIG. 9 is a cross-sectional view illustrating a problem in a conventional method for manufacturing a semiconductor device.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing and each embodiment, the same or similar components are designated by the same reference numerals, and redundant explanations will be omitted.

[0015] FIG. 1 is a cross-sectional view of a semiconductor device according to a first embodiment.

[0016] The semiconductor device 1 of the first embodiment includes a semiconductor layer 2 , a silicide layer 3 , a first insulating film 4 , a second insulating film 5 , a barrier metal 6 , and a contact plug 7 .

[0017] The semiconductor layer 2 may be made of, for example, SiC, but is not limited to this and may be made of Si or the like.

[0018] The silicide layer 3 has a role of reducing contact resistance. The silicide layer 3 may be made of, for example, Ni silicide, but is not limited to this and may be made of Ti silicide or the like.

[0019] The first insulating film 4 is provided on the semiconductor layer 2. The first insulating film 4 functions as an interlayer insulating film. The first insulating film 4 may be made of, for example, SiO2, but is not limited to this and other insulating films may be used. The first insulating film 4 is preferably a single film. The first insulating film 4 also has an opening 4A which is a contact hole. The opening 4A can be formed by, for example, photolithography and etching.

[0020] The second insulating film 5 is provided on the sidewall of the opening 4A. This allows the diameter of the opening 4A to be reduced, facilitating planarization by the contact plug 7. The second insulating film 5 also has rounded corners 8. This improves coverage of the barrier metal 6 at the corners 8 and prevents peeling of the barrier metal 6 at the corners 8. The second insulating film 5 on the sidewall with such rounded corners 8 can be formed by etch-back. This allows the second insulating film 5 to be formed in a self-aligned manner without the need for an additional photomask used in photolithography. The second insulating film 5 may be made of, for example, SiO2, but is not limited to this and other insulating films may also be used.

[0021] The barrier metal 6 is provided on the first insulating film 4, the corner portions 8 of the second insulating film 5, the sidewalls of the second insulating film 5, and the silicide layer 3. The barrier metal 6 may be, for example, a laminated film composed of a first barrier metal 6A on the lower layer and a second barrier metal 6B on the upper layer. The first barrier metal 6A may be, for example, Ti, and the second barrier metal 6B may be, for example, TiN, but is not limited thereto. For example, the first barrier metal 6A may be, for example, Ta, and the second barrier metal 6B may be, for example, TaN. To prevent oxidation of the first barrier metal 6A, it is desirable to use a nitride film as the second barrier metal 6B. However, the barrier metal 6 may be, for example, a laminated film of three or more layers, or a single-layer film.

[0022] The contact plug 7 fills a hole formed in the barrier metal 6 due to the opening 4A. Planarization is possible with the contact plug 7. The contact plug 7 may be made of, for example, W (tungsten), but is not limited to this and other metals may also be used.

[0023] The semiconductor device 1 of Example 1 further has an upper surface electrode (not shown) on the barrier metal 6 and the contact plug 7. This allows the upper surface side to be planarized and allows the upper surface electrode to be connected to the semiconductor layer 2 via the contact hole.

[0024] According to this embodiment, it is possible to realize a semiconductor device 1 in which planarization by the contact plug 7 is easy and the coverage of the barrier metal 6 at the corners 8 of the insulating film is good.

[0025] In this embodiment, the silicide layer 3 is provided over the entire surface inside the opening 4A, and is also provided under the second insulating film 5. This makes it possible to further reduce the contact resistance compared to when the silicide layer 3 is provided only under the barrier metal 6.

[0026] 2 is a flow chart illustrating a method for manufacturing the semiconductor device of Example 1. FIGS. 3 to 9 are cross-sectional views illustrating a method for manufacturing the semiconductor device of Example 1.

[0027] Step S1 is an opening formation step, which is a step of forming an opening 4A in the first insulating film 4 formed on the semiconductor layer 2 by photolithography and etching, as shown in FIG.

[0028] 3, step S2 is a silicide layer forming step in which a silicide layer 3 is formed on the entire surface of the semiconductor layer 2 inside the opening 4A. Specifically, for example, Ni is deposited by sputtering, Ni silicide is formed by a first annealing, the Ni is removed by wet etching, and a second annealing is performed, thereby forming Ni silicide as the silicide layer 3 at the bottom of the opening 4A.

[0029] Step S3 is a second insulating film forming process, in which a second insulating film 5 is deposited on the first insulating film 4 and inside the opening 4A as shown in Fig. 5, and the second insulating film 5 having rounded corners 8 is formed on the sidewall of the opening 4A by etching back as shown in Fig. 6. Specifically, for example, SiO2 is deposited over the entire surface by CVD, and then etched back by anisotropic etching to form sidewalls made of the second insulating film 5.

[0030] 7, a barrier metal 6 is deposited on the first insulating film 4, on the corner portions 8 of the second insulating film 5, on the sidewalls of the second insulating film 5, and on the semiconductor layer 2 inside the opening 4A (corresponding to on the silicide layer 3 provided on the semiconductor layer 2 in this embodiment). Specifically, for example, a stacked film of Ti and TiN is deposited on the entire surface by sputtering.

[0031] Step S5 is a contact plug formation process, which is a process for forming contact plugs 7 to fill holes formed in the barrier metal 6 due to the openings 4A. Specifically, as shown in Fig. 8, W (tungsten) is deposited over the entire surface by CVD to fill the insides of the contact holes, and as shown in Fig. 9, the W (tungsten) layer outside the contact holes is removed by etch-back to be flattened.

[0032] FIG. 10 is a cross-sectional view of a semiconductor device according to the second embodiment.

[0033] The semiconductor device 1 of the second embodiment differs from the first embodiment in that the silicide layer 3 is provided only under the barrier metal 6. Such a silicide layer 3 can be manufactured by forming the barrier metal 6 and then performing, for example, RTA.

[0034] FIG. 11 is a flowchart illustrating a method for manufacturing a semiconductor device according to the second embodiment.

[0035] The difference from Example 1 is that instead of the silicide layer formation step (step S2) (see FIG. 2) of Example 1 being performed after the opening formation step (step S1) and before the second insulating film formation step (step S3), the silicide layer formation step (step S2′) is performed after the barrier metal formation step (step S4) and before the contact plug formation step (S5), as shown in FIG. 11.

[0036] The silicide layer forming process of step S2′ is a process of forming a silicide with the barrier metal 6 as the silicide layer 3. Specifically, for example, RTA is performed to form Ti silicide, which is a silicide with the barrier metal 6, as the silicide layer 3.

[0037] According to this embodiment, it is possible to omit the process performed in step S2 of the first embodiment, such as the process of depositing Ni by sputtering, forming Ni silicide by the first annealing, and removing the Ni by wet etching.

[0038] In consideration of Examples 1 and 2, the silicide layer formation process (step S2 or step S2′) may be a process of forming a silicide layer 3 on at least a portion of the semiconductor layer 2 inside the opening 4A after the opening formation process (step S1) and before the contact plug formation process (step S5).

[0039] In Example 1, the silicide layer forming step (step S2) is a step of forming a silicide layer 3 on the entire surface of the semiconductor layer 2 inside the opening 4A after the opening forming step (step S1) and before the second insulating film forming step (step S3).

[0040] In addition, in Example 2, the silicide layer forming process (step S2′) is a process of forming a silicide with the barrier metal 6 as the silicide layer 3 after the barrier metal forming process (step S4) and before the contact plug forming process (step S5).

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical concept of the present invention. In addition, some or all of the configurations described in each embodiment may be combined and applied.

[0042] REFERENCE SIGNS LIST 1 semiconductor device, 2 semiconductor layer, 3 silicide layer, 4 first insulating film, 4A opening, 5 second insulating film, 6 barrier metal, 6A first barrier metal, 6B second barrier metal, 7 contact plug, 8 corner portion

Claims

1. A semiconductor device comprising: a semiconductor layer; a silicide layer provided on the semiconductor layer; a first insulating film provided on the semiconductor layer and having an opening; a second insulating film provided on a sidewall of the opening; barrier metal provided on the first insulating film, on a corner portion of the second insulating film, on the sidewall of the second insulating film, and on the silicide layer; and a contact plug for filling a hole generated in the barrier metal due to the opening, wherein the corner portion of the second insulating film has a rounded shape.

2. A semiconductor device according to claim 1, wherein the rounded shape of the corners of the second insulating film is formed by etching back.

3. The semiconductor device according to claim 1, wherein the silicide layer is also provided under the second insulating film.

4. A semiconductor device according to claim 1, wherein the silicide layer is a silicide with the barrier metal.

5. The semiconductor device according to claim 1, wherein the barrier metal is a laminated film of two or more layers.

6. The semiconductor device according to claim 1, wherein the first insulating film is a single film.

7. A method for manufacturing a semiconductor device, comprising: an opening formation step of forming an opening in a first insulating film formed on a semiconductor layer by photolithography and etching; a second insulating film formation step of depositing a second insulating film on the first insulating film and inside the opening, and forming the second insulating film having rounded corners on a sidewall of the opening by etching back; a barrier metal formation step of depositing a barrier metal on the first insulating film, the corners of the second insulating film, the sidewalls of the second insulating film, and on the semiconductor layer inside the opening; a contact plug formation step of forming a contact plug to fill a hole generated in the barrier metal due to the opening; and a silicide layer formation step of forming a silicide layer in at least a part of the semiconductor layer inside the opening after the opening formation step and before the contact plug formation step.

8. A method for manufacturing a semiconductor device according to claim 7, wherein the silicide layer forming step is a step of forming the silicide layer on the entire surface of the semiconductor layer inside the opening after the opening forming step and before the second insulating film forming step.

9. A method for manufacturing a semiconductor device according to claim 7, wherein the silicide layer forming step is a step of forming a silicide with the barrier metal as the silicide layer after the barrier metal forming step and before the contact plug forming step.

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