Method of manufacturing semiconductor device and semiconductor device

Abstract

To provide a method of manufacturing a semiconductor device, capable of improving covering capability of a protective film that protects wiring, and a semiconductor device.SOLUTION: A method of manufacturing a semiconductor device includes the steps of: forming a wiring film on a substrate; forming a resist pattern on the wiring film; etching the wiring film up to the middle of its thickness in a vertical direction with respect to the substrate while the resist pattern is formed; changing an etching condition and further etching from the middle of thickness of the wiring film to the end thereof; removing the resist patten and a deposition film formed on a side face of the wiring film by etching; and forming a protective film in a state where the wiring film on the substrate is covered.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a semiconductor device and a semiconductor device. [Background technology]

[0002] In general, in a semiconductor device, wiring is formed using a metal for connecting elements, for example, an aluminum alloy such as Al-Si or Al-Si-Cu, and on top of that, a PSG (Phosphorus Silicon Glass) film, a silicon nitride film, or a film combining these is formed as a passivation protective film by a known CVD (Chemical Vapor Deposition) method to prevent the intrusion of mobile ions from the outside. For example, Patent Document 1 describes a semiconductor device having aluminum wiring with a surface protective film formed on the upper layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-82509 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional semiconductor devices, the protective film that protects the wiring sometimes does not have sufficient coverage, which can lead to cracks, pinholes, and the like in the protective film, which can allow mobile ions and water to penetrate through these cracks.

[0005] The present disclosure has been made in consideration of the above problems, and aims to provide a semiconductor device manufacturing method and a semiconductor device that can improve the coverage of a protective film that protects wiring. [Means for solving the problem]

[0006] In order to achieve the above object, the method for manufacturing a semiconductor device of the present disclosure includes the steps of forming a wiring film on a substrate, forming a resist pattern on the wiring film, etching the wiring film in a direction perpendicular to the substrate to partway through the thickness of the wiring film while the resist pattern is formed, changing the etching conditions and further etching the wiring film from partway through the thickness to the end, removing a deposit film formed on the side of the wiring film by the resist pattern and etching, and forming a protective film to cover the wiring film on the substrate.

[0007] In addition, in order to achieve the above-mentioned object, the semiconductor device of the present disclosure comprises a substrate, wiring provided on the substrate, and a protective film covering the wiring, and the side of the wiring is perpendicular to the substrate in a region extending from the top surface of the wiring to halfway through its thickness, and extends toward the substrate in a region extending from halfway through its thickness to the surface of the substrate. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to improve the coverage of the protective film that protects the wiring. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of an example of a semiconductor device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a flow chart illustrating an example of a method for manufacturing a semiconductor device according to the present embodiment. [Figure 3A] 10A to 10C are diagrams for explaining a wiring film forming step and a resist pattern forming step. [Figure 3B] FIG. 10 is a view for explaining a first etching step. [Figure 3C] FIG. 10 is a view for explaining the second etching step. [Figure 3D] 10A to 10C are diagrams for explaining a deposition film removing step and a protective film forming step. [Figure 4] FIG. 1 is a cross-sectional view of an example of a conventional semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following embodiments do not limit the technology of the present disclosure.

[0011] FIG. 1 shows a cross-sectional view of an example of a semiconductor device 10 according to the present embodiment. As shown in FIG. 1, the semiconductor device 10 according to the present embodiment includes a substrate 12, wiring 14, and a protective film 16. In this embodiment, the substrate 12 also includes a substrate such as silicon on which elements, insulating films, and the like are formed according to desired characteristics. Therefore, in FIG. 1, the top surface of the substrate 12, on which the wiring 14 is provided, is depicted as a flat surface, but in reality, it may not be flat and may have irregularities.

[0012] The wiring 14 is a metal wiring film provided in a desired shape on the surface 12U of the substrate 12. Examples of metals that form the wiring 14 include aluminum alloys such as Al-Si and Al-Si-Cu, and copper (Cu). As an example, in this embodiment, an aluminum alloy film is used as the wiring 14. Note that while FIG. 1 shows a state in which two wirings 14 are provided, the number of wirings 14 provided in the semiconductor device 10 is not limited to two.

[0013] 1, the wiring 14 of this embodiment has a shape that widens toward the substrate 12. Specifically, the side surface 14S of the wiring 14 is perpendicular to the substrate 12 in a region from the upper surface 14U to partway through the thickness T, and widens toward the substrate 12 in a region from partway through the thickness T to the surface 12U of the substrate 12.

[0014] The thickness T1 of the vertical portion of the side surface 14S is determined according to the angle α formed between the surface 12U of the substrate 12 and the side surface 14S of the wiring 14. When the thickness T1 is small (when the thickness T2 is large), the angle α becomes small. In this case, there is a concern that the thickness t of the protective film 16 covering the side surface 14S of the wiring 14 may be smaller than desired. On the other hand, when the thickness T2 is small (when the thickness T1 is large), the angle α becomes large. In this case, there is also a concern that the thickness t of the protective film 16 covering the side surface 14S of the wiring 14 may be smaller than desired.

[0015] Furthermore, as the angle α increases, the width d corresponding to the region where the side surface 14S of the wiring 14 flares out, i.e., the closer the cross-sectional shape of the wiring 14 becomes to a trapezoid, the smaller the cross-sectional area becomes, and the higher the current density becomes, which raises the risk of disconnection due to electromigration.

[0016] In view of these conditions, in this embodiment, the angle α is set to about 45 degrees, and the thickness T1 of the wiring 14 is set to be equal to or greater than ½ and equal to or less than ¾ of the thickness T of the wiring 14. Note that the specific angle α and the thickness T1 of the wiring 14 may be determined depending on the material of the wiring 14, or preferred values ​​may be obtained through experiments, etc.

[0017] The spacing i between the wirings 14 need only be equal to or greater than the minimum pattern spacing specified for the semiconductor device 10, and is specifically determined according to the specifications required for the semiconductor device 10 and the layout of the circuits mounted on the substrate 12, etc.

[0018] The protective film 16 is a so-called passivation protective film for protecting the wiring 14 from mobile ions and moisture. Examples of the protective film 16 include a PSG (Phosphorus Silicon Glass) film, a silicon nitride film, or a film that is a combination of these. The specific material used for the protective film 16 may be determined depending on the material of the wiring 14, such as a metal. The thickness t of the protective film 16 in this embodiment is uniform and can be considered to be the same on the top surface 14U of the wiring 14, the side surface 14S of the wiring 14, and the surface 12U of the substrate 12.

[0019] Next, a method for manufacturing the semiconductor device 10 will be described. Fig. 2 shows a flow diagram illustrating an example of the flow of the method for manufacturing the semiconductor device 10. Note that, here, the steps of providing the wiring 14 and the protective film 16 of the semiconductor device 10 will be described in detail.

[0020] 2, the method for manufacturing a semiconductor device according to this embodiment includes a wiring film forming step, a resist pattern forming step, a first etching step, a second etching step, a deposit film removing step, and a protective film forming step. Each step will be described below with reference to FIGS. 3A to 3D.

[0021] The wiring film forming process is a process of forming a wiring film 40 on the substrate 12. In the wiring film forming process, as shown in FIG. 3A, the wiring film 40 that will become the wiring 14 is formed on the substrate 12 having elements, insulating films, etc. formed by a known method. In this embodiment, since aluminum wiring is used as the wiring 14, the wiring film 40 is formed on the surface 12U of the substrate 12 by a sputtering method. For example, an Al-Si or Al-Si-Cu film is formed.

[0022] The next resist pattern forming step is a step of forming a resist pattern 50 on the wiring film 40. In the resist pattern forming step, as shown in Fig. 3A, a resist pattern 50 is formed on the upper surface 40U of the wiring film 40 by a known photolithography method.

[0023] The next first etching step is a step of etching the wiring film 40 perpendicular to the substrate 12 to a depth T of the wiring film 40 while the resist pattern 50 is formed. In the first etching step of this embodiment, as shown in FIG. 3B, CH4, Ar, Cl2, and BCl3 are used as etching gas 51, and the aluminum alloy film is dry-etched in a dry etching apparatus. By using CH4 and Ar as etching gas 51, an organic deposition film 52 is formed, and the wiring film 40, which is an aluminum alloy film, is etched approximately perpendicularly to a depth of 1 / 2 to 3 / 4 of the thickness of the wiring film 40. The thickness of the wiring film 40 corresponds to the thickness T of the wiring 14 described above. The etching method for the wiring film and the specific type of etching gas 51 may be selected depending on the material of the wiring film 40.

[0024] In the next second etching step, the etching conditions are changed to further etch the wiring film 40 from the middle to the end of its thickness. In the second etching step of this embodiment, as shown in FIG. 3C, the etching conditions are changed to change the flow rate ratio of CH4 and Ar in the etching gas 51. Specifically, the flow rate ratio is made larger than the other ratios to increase the gas flow rate. By changing the etching conditions in this way, the thickness of the deposition film 52 is increased, and the wiring film 40 is etched in a sloped shape, i.e., so that the base widens toward the surface 12U of the substrate 12.

[0025] Unlike this embodiment, when dry etching is performed by an etching apparatus using CHF3, Cl2, and BCl3 as the etching gas 51, the flow rate ratio of CHF3 may be changed.

[0026] The next deposition film removal step is a step of removing the resist pattern 50 and the deposition film 52 formed on the side surface of the wiring film 40 by etching. In the deposition film removal step, as shown in FIG. 3D, the resist pattern 50 and the deposition film 42 are removed by a known method. By this step, the wiring 14 having the shape shown in FIG. 1 is formed from the wiring film 40.

[0027] The next protective film forming step is a step of forming a protective film 16 so as to cover the wiring film 40 on the substrate 12. In this embodiment, as shown in FIG. 3D, in the protective film forming step, a PSG film, a silicon nitride film, or a combination thereof is formed as the protective film 16 by a known method. Specifically, after forming a passivation film, a pattern is formed by photolithography, and then etching is performed to cover the entire wiring film 40 (wiring 14) with the protective film 16. When this step is completed, the semiconductor device 10 shown in FIG. 1 is obtained.

[0028] As described above, the method for manufacturing a semiconductor device of this embodiment includes a wiring film formation process for forming a wiring film 40 on the substrate 12, a resist pattern formation process for forming a resist pattern 50 on the wiring film 40, a first etching process for etching the wiring film 40 in a direction perpendicular to the substrate 12 to partway through the thickness of the wiring film 40 with the resist pattern formed, a second etching process for changing the etching conditions and further etching the wiring film 40 from partway through the thickness to the end, a deposit film removal process for removing the resist pattern 50 and the deposit film 52 formed on the side of the wiring film 40 by etching, and a process for forming a protective film 16 to cover the wiring film 40 on the substrate 12.

[0029] FIG. 4 shows a cross-sectional view of an example of a conventional semiconductor device different from this embodiment. The entire side of the wiring 140 of the conventional semiconductor device 100 shown in FIG. 4 is perpendicular to the surface of the substrate 120. That is, the bottom of the wiring 140 does not flare out. When a protective film 160 such as a silicon nitride film is formed on the wiring (wiring film) 140 having such a shape by a CVD method, e.g., a plasma enhancement method, the film coverage at the bottom of the wiring 140 is poor due to the characteristics of the film formation, as shown in FIG. 4. Specifically, the thickness of the protective film 160 covering the side of the wiring 160 is thinner than other areas. As a result, in areas where the wiring spacing is narrow, only the top of the protective film 160 comes into contact, creating tunnel-shaped cavities 161. During a subsequent photolithography process for the protective film 160, the resist for the protective film 160 is sucked into the cavities 161 by capillary action, resulting in thinned resist areas. In these thinned resist areas, the protective film 160 may be etched in a subsequent etching process, resulting in defects. Furthermore, if stress is applied to areas where coverage is poor, defects 162 such as cracks or pinholes may occur in the protective film 160. Mobile ions or water may penetrate through these defects 162, causing problems such as changes in the characteristics of elements formed on the substrate 120 or corrosion of the wiring 140.

[0030] In contrast to such conventional techniques, in the semiconductor device 10 of this embodiment, the shape of the wiring 14 can be such that the side surface of the region from the top surface 14U of the wiring 14 to the middle of the thickness T is perpendicular to the substrate 12, and the region from the middle of the thickness T to the surface 12U of the substrate 12 widens toward the substrate 12. This makes it possible to make the thickness t of the protective film 16 uniform. Therefore, according to the manufacturing method of the semiconductor device 10 of this embodiment, it is possible to improve the coverage of the protective film 16 that protects the wiring 14. This reduces the risk of the problems with the conventional semiconductor device 100 described above.

[0031] In the above embodiment, the flow rate ratio of CH4 and Ar in the etching gas 51 is used as the etching condition to be changed in the second etching step. However, the etching condition is not limited to the flow rate ratio. For example, the flow rate of the etching gas 51 may be changed. In this case, the flow rate of the etching gas 51 is increased to change the overall gas flow rate. The etching condition may also be the pressure or power of the etching gas 51. Furthermore, multiple etching conditions, such as both the flow rate ratio and the rate, may be changed. Furthermore, the first etching step and the second etching step of the above embodiment may be performed as one step by combining a recipe and performing etching successively. That is, with the resist pattern 50 formed, the wiring film 40 may be etched in the direction perpendicular to the substrate 12 to a depth T of the wiring film 40, and then the etching conditions may be changed to etch the remaining portion of the wiring film 40.

[0032] The following additional notes are provided regarding the above-described embodiments. (Appendix 1) forming a wiring film on a substrate; forming a resist pattern on the wiring film; a step of etching the wiring film in a direction perpendicular to the substrate to a part of the thickness of the wiring film while the resist pattern is formed; changing the etching conditions and further etching the wiring film from the middle to the end of its thickness; removing a deposit film formed on a side surface of the wiring film by the resist pattern and etching; forming a protective film so as to cover the wiring film on the substrate; A method for manufacturing a semiconductor device comprising:

[0033] (Appendix 2) The etching conditions are conditions for etching the wiring film into a shape that widens toward the substrate. The method for manufacturing the semiconductor device according to claim 1.

[0034] (Appendix 3) The etching conditions include at least one of a flow rate ratio of an etching gas and an etching rate. A method for manufacturing a semiconductor device according to claim 1 or 2.

[0035] (Appendix 4) The etching is dry etching. 4. A method for manufacturing a semiconductor device according to any one of claims 1 to 3.

[0036] (Appendix 5) A substrate; Wiring provided on the substrate; a protective film covering the wiring; Equipped with The side surface of the wiring is perpendicular to the substrate in a region extending from the top surface of the wiring to the middle of the thickness thereof, and the region extending from the middle of the thickness thereof to the surface of the substrate widens toward the substrate. Semiconductor device. [Explanation of symbols]

[0037] 10 Semiconductor devices 12 PCB 14 Wiring 16 Protective film 40 Wiring film 50 Resist Pattern 52 Depot membrane

Claims

1. forming a wiring film on a substrate; forming a resist pattern on the wiring film; a step of etching the wiring film in a direction perpendicular to the substrate to a part of the thickness of the wiring film while the resist pattern is formed; changing the etching conditions and further etching the wiring film from the middle to the end of its thickness; removing a deposit film formed on a side surface of the wiring film by the resist pattern and etching; forming a protective film so as to cover the wiring film on the substrate; A method for manufacturing a semiconductor device comprising:

2. The etching conditions are conditions for etching the wiring film into a shape that widens toward the substrate. The method for manufacturing a semiconductor device according to claim 1 .

3. The etching conditions include at least one of a flow rate ratio of an etching gas and an etching rate. The method for manufacturing a semiconductor device according to claim 1 .

4. The etching is dry etching. The method for manufacturing a semiconductor device according to claim 1 .

5. A substrate; Wiring provided on the substrate; a protective film covering the wiring; Equipped with The side surface of the wiring is perpendicular to the substrate in a region extending from the top surface of the wiring to the middle of the thickness thereof, and the region extending from the middle of the thickness thereof to the surface of the substrate widens toward the substrate. Semiconductor device.

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