Manufacturing method of metal compound film

Abstract

The method for manufacturing a metal compound film of the present invention is characterized by coating a compound generating liquid containing a substance that generates a metal compound on a substrate (11) having an opening (12) on its surface, and firing it to form a metal compound film (15). The method is characterized by coating a pre-wetting liquid (21) with a better wettability between the aforementioned compound generating liquid and the substrate (11) on the surface of the substrate (11), filling the opening (12) with the pre-wetting liquid (21), coating the aforementioned compound generating liquid with the pre-wetting liquid (21) deposited on the substrate (11), diffusing the aforementioned solute component of the aforementioned compound generating liquid into the pre-wetting liquid (21) with the pre-wetting liquid (21), coating the aforementioned compound generating liquid, and firing the aforementioned compound generating liquid to form a metal compound film (15).

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a metal compound film used as a hard mask during etching. This application claims priority based on Japanese Patent Application No. 2021-089729 filed on May 28, 2021, and Japanese Patent Application No. 2022-086014 filed on May 26, 2022, the contents of which are incorporated herein by reference. [Previous Technology]

[0002] In the past, for example in semiconductor processes, polymer or organic photoresist was widely used as an etching mask when patterns were formed on the surface of substrates such as silicon for etching. However, polymers are susceptible to etching due to their susceptibility to reactive gases such as oxygen, fluorine, and chlorine. Organic photoresist, on the other hand, is prone to degradation during plasma etching.

[0003] Here, in particular as an etching mask during plasma etching, for example as shown in Patent Documents 1-3, a hard mask made of a metal compound film such as a metal oxide, metal nitride, or metal oxynitride is provided. Metal compound films are particularly suitable as hard masks because they are resistant to plasma etching and are relatively easy to peel off from strongly acidic liquids. As a method for forming the aforementioned metal compound film on the substrate surface, the sol-gel method using a sol-gel solution can be cited. By coating the metal compound sol-gel solution onto the substrate surface and then firing it, a simpler manufacturing process can be used to form the metal compound film.

[0004] Here, there are cases where various openings, such as trenches or holes, are pre-formed on the surface of the substrate. When the metal compound film is used as a hard mask, a metal compound is filled into the openings to form a metal compound film.

[0005] Recently, in the semiconductor field, with the advancement of miniaturization and high integration, there is a tendency for the opening area of ​​trenches or holes formed on the surface of substrates to become narrower. When sol-gel liquid is coated on substrates with narrow opening areas, the sol-gel liquid may not be able to fully fill the openings due to the surface tension of the sol-gel liquid, raising concerns that many voids may exist in the metal compound film formed after firing.

[0006] As a method for filling such an opening with a metal compound to form a metal compound film, atomic layer deposition (ALD) is an example of CVD. Furthermore, Patent Document 1 proposes a method for forming a metal compound film by reducing the interfacial energy between the side and bottom surfaces of the opening to promote the filling of a liquid-like filling material (sol-gel solution) into the opening. [Prior Art Documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-510366 (A) [Patent Document 2] Japanese Patent Application Publication No. 10-194873 (A) [Patent Document 3] Japanese Patent Application Publication No. 2014-077082 (A) [Summary of the Invention]

[0008] [The problem the invention aims to solve]

[0009] However, the manufacturing cost of the atomic layer deposition method described above is very high, making it difficult to use widely in industry. Furthermore, in Patent Document 1, the manufacturing process becomes very complex due to the need for a process to reduce the interface energy on the side and bottom surfaces of the opening, which may result in the inefficient formation of metal compound films.

[0010] This invention was made in view of the above-mentioned circumstances, and aims to provide a method for manufacturing a metal compound film in which a metal compound film with few voids can be efficiently formed by filling the aforementioned openings when forming a metal compound film on a substrate having openings on its surface. [Means for solving the problem]

[0011] To solve the above-mentioned problems, the method for manufacturing a metal compound film according to aspect 1 of the present invention is characterized by forming a metal compound film by coating a compound generating liquid containing a metal compound as a solute component onto a substrate having an opening on its surface and then firing it. The method comprises: a pre-wetting liquid coating process in which a pre-wetting liquid with better wettability than the compound generating liquid and the substrate is coated on the surface of the substrate and the pre-wetting liquid is filled into the opening; a compound generating liquid coating process in which the pre-wetting liquid deposited on the substrate is coated with the compound generating liquid and the solute component of the compound generating liquid is diffused into the pre-wetting liquid; and a firing process in which the compound generating liquid is fired to form a metal compound film.

[0012] According to the manufacturing method of the metal compound film of Embodiment 1 of the present invention, since a pre-wetting liquid with good wettability to the substrate is coated on the surface of the aforementioned substrate (the solute component of which is a compound generating liquid containing a substance that generates the metal compound), the openings on the substrate surface can be sufficiently filled with the pre-wetting liquid. Then, with the openings on the substrate surface filled with the pre-wetting liquid, the compound generating liquid is coated, and the solute component of the compound generating liquid diffuses into the pre-wetting liquid, filling the openings on the substrate surface with the solute component of the compound generating liquid. In this state, by performing a firing process, a metal compound film with few voids filling the openings on the substrate surface can be formed. Furthermore, a metal compound film with few voids can be formed efficiently with a simpler manufacturing process.

[0013] The second aspect of the present invention is a method for manufacturing a metal compound film according to aspect 1, characterized by: a drying process in which the aforementioned compound generating liquid is a sol-gel liquid, the aforementioned sol-gel liquid is dried and coated to form a metal compound gel film, and a firing process in which the aforementioned metal compound gel film is fired to form a metal compound film. According to the method for manufacturing a metal compound film according to aspect 2 of the present invention, the method includes a drying process in which the aforementioned compound generating liquid is a sol-gel liquid, the aforementioned sol-gel liquid is dried and coated to form a metal compound gel film, and a firing process in which the aforementioned metal compound gel film is fired to form a metal compound film. The sol-gel liquid can be used to form a metal compound film with minimal voids in the openings on the surface of the substrate.

[0014] In the manufacturing method of the metal compound film of the present invention, which is based on the first or second embodiment, the pre-wetting liquid coating process is characterized by coating the pre-wetting liquid by spin coating. Because the metal compound film of the present invention is manufactured by spin coating, the pre-wetting liquid can be sufficiently filled into the opening on the substrate surface.

[0015] In the manufacturing method of any of the metal compound films of Embodiments 1 to 3 of the present invention, the pre-wetting liquid is characterized by being a supercritical fluid in the aforementioned pre-wetting liquid coating process. According to the manufacturing method of the metal compound film of Embodiment 4 of the present invention, because the aforementioned pre-wetting liquid is a supercritical fluid, the wettability with the substrate is improved, and the pre-wetting liquid can be sufficiently filled into the openings on the substrate surface. [Effects of the Invention]

[0016] According to the present invention, a method for manufacturing a metal compound film is provided in which, when a metal compound film is formed on a substrate having an opening on its surface, a metal compound film can be filled in the opening and a metal compound film with few voids can be efficiently formed.

Implementation Method

[0018] Hereinafter, a method for manufacturing a metal compound film according to an embodiment of the present invention will be described. In this embodiment, the method for manufacturing a metal compound film involves, for example, a metal compound film formed on the surface of a substrate such as a semiconductor wafer, used as a hard mask during etching. However, in this embodiment, a metal oxide film, one type of metal compound film, will be described. Furthermore, in this embodiment, a sol-gel solution containing a metal oxide will be used as the compound forming liquid.

[0019] In the manufacturing method of the metal compound film of this embodiment, as shown in FIG2, a metal oxide film 15 is formed on a substrate 11 with openings 12 such as trenches or holes formed on its surface. Here, in this embodiment, the openings 12 are trenches with an opening width of 10 nm to 3 μm and a depth of 5 nm to 500 nm. Examples of substrates 11 include silicon substrates, sapphire substrates, and GaN substrates. In this embodiment, a silicon substrate is used.

[0020] Furthermore, although the metal oxide constituting the metal oxide film 15 is not specifically limited and various metal oxides can be used, in this embodiment it contains one or more of aluminum oxide, hafnium oxide, zirconium oxide, tungsten oxide, and titanium oxide. This metal oxide film 15 is formed by firing a sol-gel solution 22 containing metal oxides.

[0021] Then, in the manufacturing method of the metal compound film of this embodiment, as shown in FIG1 and FIG2, there are: a pre-wetting liquid 21 with better wettability between the sol-gel liquid 22 and the substrate 11 is coated on the surface of the substrate 11; a pre-wetting liquid coating process S01 is performed to fill the opening 12 with the pre-wetting liquid 21; a sol-gel liquid coating process S02 is performed to coat the sol-gel liquid 22 with the pre-wetting liquid 21 deposited on the substrate 11; a sol-gel liquid coating process S03 is performed to dry the coated sol-gel liquid 22 to form a metal oxide gel film 24; and a firing process S04 is performed to fire the metal oxide gel film 24 to form a metal oxide film 15. The contact angle with respect to the substrate 11 of the pre-wetting liquid 21 is smaller than the contact angle with respect to the substrate 11 of the sol-gel liquid 22. For the substrate 11 of the pre-wetted liquid 21, a contact angle of 50° or less is preferred, and for the substrate 11 of the sol-gel liquid 22, a contact angle of 80° or less is preferred. Such contact angles are preferably small, i.e., close to 0°. For the substrate 11 of the pre-wetted liquid 21, a contact angle of 1° or more is preferred, and for the substrate 11 of the sol-gel liquid 22, a contact angle of 0° or more is preferred.

[0022] In the pre-wetting liquid coating process S01, as described above, since the pre-wetting liquid 21 has better wettability than the sol-gel liquid 22 to the substrate 11, the opening 12 formed on the surface of the substrate 11 is filled with the pre-wetting liquid 21. However, as shown in FIG2, it is possible not to fill the entire opening 12 with the pre-wetting liquid 21, or at least to sufficiently wet the bottom area of ​​the opening 12 with the pre-wetting liquid 21. As the pre-wetting liquid 21, it is preferable to use alcohols with 4 or fewer carbon atoms such as pure water and ethanol, or alcohols with ether bonds such as propylene glycol monomethyl ether (PGME).

[0023] Furthermore, in the pre-wetting liquid coating process S01, it is preferable to apply the pre-wetting liquid 21 by spin coating. By using spin coating, the opening 12 can be fully filled with the pre-wetting liquid 21. Moreover, it is preferable to apply the pre-wetting liquid 21 as a supercritical fluid that is above the critical temperature and critical pressure. Because supercritical fluids have particularly excellent wettability, the opening 12 can be fully filled with the pre-wetting liquid 21.

[0024] In the sol-gel coating process S02, as described above, the sol-gel 22 is coated by applying the pre-wetting liquid 21 deposited on the substrate 11, allowing the solute components of the sol-gel 22 to diffuse into the pre-wetting liquid 21. The sol-gel 22 is also coated by spin coating. Thus, the opening 12 is also sufficiently filled with the solute components of the sol-gel 22. However, the solute components of the sol-gel 22 diffuse into the pre-wetting liquid 21, for example, after standing for 5 to 10 seconds. However, in this embodiment, the solute components of the sol-gel 22 include, for example, one or more selected from aluminum alkoxide, hafnium alkoxide, zirconium alkoxide, tungsten alkoxide, and silicon alkoxide. Furthermore, the solvent for the sol-gel 22 can be, for example, ethanol, 1-butanol, PGME, etc.

[0025] In the drying process S03, the substrate 11 coated with the pre-wet liquid 21 and the sol-gel liquid 22 is dried by heating to form a metal oxide gel film 24. As described above, since the solute component of the sol-gel liquid 22 is filled into the opening 12, the metal oxide gel can be filled into the opening 12. The heating conditions for this drying process S03 are preferably atmospheric conditions, with the heating temperature in the range of 50°C to 300°C, and the holding time of the heating temperature in the range of 1 minute to 10 minutes.

[0026] Here, a metal oxide gel film 24 of a specific thickness is formed by repeatedly performing the sol-gel coating process S02 and the drying process S03. However, after the drying process S03, when the 12 openings are inserted, the pre-wetting coating process S01, the sol-gel coating process S02, and the drying process S03 may also be repeated. When repeating, the pre-wetting coating process S01 may be omitted after the second repetition.

[0027] In the firing process S04, the aforementioned metal oxide gel film 24 is fired by heating to form a metal oxide film 15. As described above, since the opening 12 is filled with metal oxide gel, the opening 12 can also be filled with metal oxide. The heating conditions for this firing process S04 are preferably in an atmospheric or oxygen environment, with the heating temperature in the range of 400°C to 800°C, and the holding time of the heating temperature in the range of 3 minutes to 10 minutes. However, when repeating the sol-gel coating process S02 and the drying process S03, the firing process S04 can also be performed after each drying process S03.

[0028] The metal oxide film 15 of this embodiment is manufactured through the above process.

[0029] In the manufacturing method of the metal compound film according to the above-described embodiment, in the pre-wetting liquid coating process S01, since the pre-wetting liquid 21 with better wettability to the substrate 11 than the sol-gel liquid 22 is coated on the surface of the substrate 11, the pre-wetting liquid 21 can be fully filled into the opening 12 on the surface of the substrate 11.

[0030] Then, in the sol-gel coating process S02, with the pre-wetting liquid 21 filled in the opening 12 of the substrate 11, the sol-gel 22 is coated. The solute components of the sol-gel 22 diffuse into the pre-wetting liquid 21, filling the opening 12 of the substrate 11 with the solute components of the sol-gel. In this state, by performing the drying process S03 and the firing process S04, a metal oxide film 15 with minimal voids in the metal oxide can be formed in the opening 12 of the substrate 11.

[0031] In this embodiment, during the pre-wetting liquid coating process S01, when the pre-wetting liquid 21 is coated by spin coating, the pre-wetting liquid 21 can be fully filled into the opening 12 of the substrate 11. As a result, the metal oxide can be reliably filled into the opening 12 of the substrate 11, and a metal oxide film 15 with few voids can be formed.

[0032] In this embodiment, during the pre-wetting liquid coating process S01, when the pre-wetting liquid 21 is coated as a supercritical fluid above the critical temperature and critical pressure, the wettability between the pre-wetting liquid 21 and the substrate 11 can be further improved, and the pre-wetting liquid 21 can be fully filled into the opening 12 of the substrate 11. As a result, the metal oxide can be reliably filled into the opening 12 of the substrate 11, and a metal oxide film 15 with few voids can be formed.

[0033] While embodiments of the present invention have been described above, the present invention is not limited thereto, and appropriate modifications can be made without departing from the technical concept of the invention. In this embodiment, although a sol-gel solution containing a metal oxide is used as the compound forming liquid to form a metal oxide film, this is not a limitation; the metal compound film can be a metal nitride film or a metal oxynitride film. However, when forming a silicon nitride film, or a silicon oxynitride film, as a solute component, a compound forming liquid containing polysilamidene or the like is used. [Industrial Applicability]

[0034] The present invention aims to provide a method for manufacturing a metal compound film in which a metal compound film with few voids can be efficiently formed by filling the openings in the openings when forming a metal compound film on a substrate having an opening on its surface. [Simplified Explanation of the Diagram]

[0017] [Figure 1] shows a flowchart of a method for manufacturing a metal compound film according to one embodiment of the present invention. [Figure 2] shows an explanatory diagram of a method for manufacturing a metal compound film according to one embodiment of the present invention.

Claims

1. A method for manufacturing a metal compound film, comprising coating a compound generating liquid containing a substance that generates a metal compound as a solute on a substrate having an opening on its surface and then firing it to form a metal compound film, characterized by comprising: coating a pre-wetting liquid, which has better wettability to the substrate than the compound generating liquid, on the surface of the substrate; filling the opening with the pre-wetting liquid; coating the compound generating liquid by depositing the pre-wetting liquid onto the substrate; diffusing the solute component of the compound generating liquid into the pre-wetting liquid; and firing the coated compound generating liquid to form a metal compound film, wherein the depth of the opening is set to be in the range of 5 nm to 500 nm, and the aforementioned metal compound film filled with the aforementioned metal compound is formed in the opening.

2. The method for manufacturing a metal compound film as described in claim 1, wherein, The process includes a drying process for forming a metal compound gel film by drying and coating the aforementioned compound generating liquid as a sol-gel liquid, and a firing process for forming a metal compound film by firing the aforementioned metal compound gel film.

3. A method for manufacturing a metal compound film as described in claim 1 or 2, wherein, In the aforementioned pre-wetting liquid coating process, the pre-wetting liquid is applied by spin coating.

4. A method for manufacturing a metal compound film as described in claim 1 or 2, wherein, In the aforementioned pre-wetting liquid coating process, the aforementioned pre-wetting liquid is a supercritical fluid.

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