Composition for forming protective film, protective film, method for manufacturing substrate, and method for manufacturing semiconductor device

Abstract

A composition for forming a protective film according to the invention includes a polymer having repeating units represented by formula (1) below and a solvent. The content of the polymer is 80 mass% or more relative to the nonvolatile content of the composition for forming the protective film. (In formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.　R2 represents a single bond or -CH2-.　R3 represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. 　X1 represents -O- or -NH-.　Y1 represents -NH-, -S-, -C(=O)-O-, or -O-C(=O)-.　n represents an integer from 2 to 5.)

Description

Composition for forming a protective film, protective film, method for manufacturing a substrate, and method for manufacturing a semiconductor device.

[0001] The present invention relates to a composition for forming a protective film with particularly excellent resistance to semiconductor wet etching solutions in a lithography process for semiconductor manufacturing. The invention also relates to a protective film formed from the composition, a method for manufacturing a substrate with a resist pattern to which the protective film is applied, and a method for manufacturing a semiconductor device.

[0002] In semiconductor manufacturing, the lithography process, which involves forming a resist underlayer film between a substrate and a resist film formed on it to create a resist pattern of a desired shape, is widely known. After forming the resist pattern, the substrate is processed, and dry etching is mainly used for this process, although wet etching may be used depending on the type of substrate. Patent Document 1 discloses a resist underlayer film material that has resistance to alkaline hydrogen peroxide solution.

[0003] Japanese Patent Publication No. 2018-173520

[0004] When forming a protective film on a semiconductor substrate using a protective film-forming composition, and then processing the underlying substrate by wet etching using the protective film as an etching mask, the protective film is required to have good masking function against semiconductor wet etching solutions (i.e., the masked portion can protect the substrate) and resistance to solvents contained in the resist composition (solvent resistance).

[0005] The present invention has been made in view of the above circumstances, and aims to provide a protective film forming composition that can form a protective film that has excellent resistance to solvents contained in a resist composition and excellent resistance to semiconductor wet etching solutions. The present invention also aims to provide a protective film formed from the protective film forming composition, a method for manufacturing a resist patterned substrate to which the protective film is applied, and a method for manufacturing a semiconductor device.

[0006] The inventors of the present invention conducted diligent research to solve the aforementioned problems and, as a result, discovered that the aforementioned problems can be solved by incorporating a specific polymer into the protective film-forming composition, thereby completing the present invention.

[0007] That is, the present invention includes the following aspects. [1] A composition for forming a protective film, comprising a polymer having a repeating unit represented by the following formula (1) and a solvent, wherein the content of the polymer is 80% by mass or more based on the non-volatile content of the composition for forming a protective film. (In formula (1), R １ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ２ represents a single bond or -CH ２ -. R ３ represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. X １ represents -O- or -NH-. Y １ represents -NH-, -S-, -C(=O)-O- or -O-C(=O)-. n represents an integer of 2 to 5.) [2] The composition for forming a protective film according to [1], wherein the repeating unit represented by the formula (1) is a repeating unit represented by the following formula (1-1). (In formula (1-1), R １ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ２ represents a single bond or -CH ２ -. R ３ represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. X １ represents -O- or -NH-. Y １) represents -NH-, -S-, -C(=O)-O- or -O-C(=O)-. n represents an integer from 2 to 5. ) [3] The protective film forming composition according to [1], wherein the molar ratio of the repeating unit represented by formula (1) is 80 mol% or more with respect to the total repeating units of the polymer. [4] The protective film forming composition according to any one of [1] to [3], which does not contain a crosslinking agent. [5] The protective film forming composition according to any one of [1] to [4], which contains a curing catalyst. [6] The protective film forming composition according to any one of [1] to [5], which is a protective film forming composition for forming a protective film that protects the inorganic film on a semiconductor substrate having an inorganic film formed on its surface from wet etching. [7] A protective film for semiconductor wet etching solutions, which is a fired product of a coating film made from the protective film forming composition according to any one of [1] to [6]. [8] A method for manufacturing a substrate with a protective film, comprising the steps of applying a protective film-forming composition according to any one of [1] to [6] onto a semiconductor substrate having steps and firing to form a protective film. [9] A method for manufacturing a substrate with a resist pattern, used in the manufacture of a semiconductor, comprising the steps of applying a protective film-forming composition according to any one of [1] to [6] onto a semiconductor substrate and firing to form a protective film as a resist underlayer film, and forming a resist film directly or via another layer on the protective film, then exposing and developing to form a resist pattern.

[10] A method for manufacturing a semiconductor device, comprising the steps of forming a protective film on a semiconductor substrate having an inorganic film formed on its surface using a protective film-forming composition according to any one of [1] to [6], forming a resist pattern directly or via another layer on the protective film, dry etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film, and wet etching the inorganic film using a semiconductor wet etching solution with the dry-etched protective film as a mask.

[0008] According to the present invention, it is possible to provide a protective film-forming composition that can form a protective film that has excellent resistance to solvents contained in a resist composition and excellent resistance to semiconductor wet etching solutions. Furthermore, according to the present invention, it is possible to provide a protective film formed from the protective film-forming composition, a method for manufacturing a substrate with a resist pattern to which the protective film is applied, and a method for manufacturing a semiconductor device.

[0009] (Composition for forming a protective film) The protective film-forming composition of the present invention comprises a polymer and a solvent. The protective film-forming composition of the present invention is a composition for forming a protective film. The polymer content in the protective film-forming composition is 80% by mass or more relative to the non-volatile content of the protective film-forming composition. The protective film is preferably a protective film that protects the inorganic film on a semiconductor substrate, on which an inorganic film is formed on the surface, from wet etching.

[0010] <Polymer (A)> The polymer (hereinafter sometimes referred to as "Polymer (A)") has repeating units represented by the following formula (1). Polymer (A) may further have other repeating units. (In formula (1), R １ R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ This is a single bond, or -CH ２ Represents -. R ３ X represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. １ This represents -O- or -NH-. １ represents -NH-, -S-, -C(=O)-O-, or -O-C(=O)-. n represents an integer between 2 and 5.

[0011] The following structure (P) of the repeating unit represented by formula (1) is thought to impart resistance (chemical resistance) to semiconductor wet etching solutions to the protective film formed from the protective film forming composition of the present invention. (In equation (P), n represents an integer between 2 and 5. * represents a combination.)

[0012] The hydroxyl groups (not phenolic hydroxyl groups) of the repeating units represented by formula (1) have dehydration condensation properties, and therefore the protective film formed from the protective film-forming composition of the present invention has a crosslinked structure. For this reason, the protective film formed from the protective film-forming composition of the present invention has resistance to solvents contained in the resist composition (solvent resistance).

[0013] By having a polymer (A) content of 80% by mass or more relative to the non-volatile content of the protective film-forming composition, the protective film obtained from the protective film-forming composition can fully exhibit chemical resistance and solvent resistance due to polymer (A).

[0014] Therefore, by using the protective film-forming composition of the present invention, a protective film can be formed that has excellent resistance to solvents contained in the resist composition and excellent resistance to semiconductor wet etching solutions.

[0015] <<Repeating unit represented by formula (1)>> (In formula (1), R １ R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ This is a single bond, or -CH ２ Represents -. R ３ X represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. １ This represents -O- or -NH-. １ represents -NH-, -S-, -C(=O)-O-, or -O-C(=O)-. n represents an integer between 2 and 5.

[0016] As for the repeating unit represented by formula (1), the repeating unit represented by formula (1-1) below is preferred in that it provides better chemical resistance, and the repeating unit represented by formula (1-1-1) is even more preferred. (In equations (1-1) and (1-1-1), R １ R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ This is a single bond, or -CH ２ Represents -. R ３ X represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. １This represents -O- or -NH-. １ represents -NH-, -S-, -C(=O)-O-, or -O-C(=O)-. n represents an integer between 2 and 5.

[0017] In equations (1), (1-1), and (1-1-1), R １ Examples include hydrogen atoms and methyl groups.

[0018] In equations (1), (1-1), and (1-1-1), n ​​may be 2, 3, 4, or 5.

[0019] R ３ The number of carbon atoms in the divalent chain hydrocarbon group having 1 to 20 carbon atoms may be 1 to 10 or 1 to 5. The divalent chain hydrocarbon group having 1 to 20 carbon atoms may or may not have carbon-carbon multiple bonds. An example of a divalent chain hydrocarbon group having 1 to 20 carbon atoms is an alkylene group.

[0020] Examples of repeating units represented by equation (1) include the following structures.

[0021] The proportion of repeating units represented by formula (1) in polymer (A) is not particularly limited, but from the viewpoint of suitably obtaining the effects of the present invention, it is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 100 mol% relative to the total repeating units of polymer (A).

[0022] The weight-average molecular weight Mw of polymer (A) is not particularly limited, but is preferably 300 or more, more preferably 500 or more, even more preferably 1,000 or more, even more preferably 1,500 or more, and particularly preferably 2,000 or more. There is also no particular upper limit to the weight-average molecular weight Mw, but it is preferable that the weight-average molecular weight Mw is 500,000 or less. In the present invention, the weight-average molecular weight Mw is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0023] The polymer (A) content in the protective film-forming composition is 80% by mass or more, preferably 81% to 99% by mass, more preferably 83% to 98% by mass, and particularly preferably 85% to 97% by mass, relative to the non-volatile content. Non-volatile content refers to components other than the solvent in the protective film-forming composition.

[0024] The method for producing polymer (A) is not particularly limited. Polymer (A) can be produced by polymerizing monomers by conventional methods, such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization. Solution polymerization is particularly preferred, in which case monomers can be polymerized using, for example, a polymerization initiator.

[0025] Examples of monomers that give polymer (A) the repeating units represented by formula (1) include monomers represented by the following formula (1A). (In formula (1A), R １ , R ２ , R ３ , X １ , Y １ , and n are, respectively, R in equation (1) １ , R ２ , R ３ , X １ , Y １ (This is synonymous with n.)

[0026] Organic peroxides and diazo compounds can be used as polymerization initiators.

[0027] Examples of organic peroxides include diacyl peroxides, peroxydicarbonates, peroxyesters, and sulfonate peroxides. Examples of diacyl peroxides include diacetyl peroxide, diisobutyl peroxide, didecanoyl peroxide, benzoyl peroxide, and succinate peroxide. Examples of peroxydicarbonates include diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diallyl peroxydicarbonate. Examples of peroxyesters include tert-butyl peroxyisobutyrate, tert-butyl neodecanate, and cumene peroxyneodecanate. Examples of sulfonate peroxides include acetylcyclohexylsulfonyl peroxide.

[0028] Examples of diazo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(isobutyrate)dimethyl, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(4-methoxy-2,4-dimethoxyvaleronitrile), and 2,2'-azobis(2-cyclopropylpropionitrile).

[0029] If polymerization is to be completed in a short time, it is preferable to use a polymerization initiator that has a decomposition half-life of 10 hours or less at 80°C. Suitable polymerization initiators include benzoyl peroxide and 2,2'-azobisisobutyronitrile, with 2,2'-azobisisobutyronitrile being more preferred.

[0030] The amount of polymerization initiator used is, for example, 0.0001 to 0.3 equivalents, preferably 0.0005 to 0.2 equivalents, relative to the total amount of monomer used.

[0031] The solvent used for polymerization is not particularly limited as long as it does not participate in the polymerization reaction and is compatible with the resulting polymer. Examples include aromatic hydrocarbons, alicyclic hydrocarbons, aliphatic hydrocarbons, ketones, ethers, esters, amides, sulfoxides, alcohols, and polyhydric alcohol derivatives. Examples of aromatic hydrocarbons include benzene, toluene, and xylene. Examples of alicyclic hydrocarbons include cyclohexane. Examples of aliphatic hydrocarbons include n-hexane and n-octane. Examples of ketones include acetone, methyl ethyl ketone, and cyclohexanone. Examples of ethers include tetrahydrofuran and dioxane. Examples of esters include ethyl acetate and butyl acetate. Examples of amides include N,N-dimethylformamide and N,N-dimethylacetamide. Examples of sulfoxides include dimethyl sulfoxide. Examples of alcohols include methanol and ethanol. Examples of polyhydric alcohol derivatives include ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate. These can be used individually or in combination of two or more.

[0032] The polymerization temperature is not particularly limited as long as it is within a temperature range where side reactions such as transfer reactions and termination reactions do not occur, and the monomer is consumed and polymerization is completed. However, it is preferable that the polymerization is carried out in a temperature range of -100°C or higher and below the boiling point of the solvent. The concentration of monomer in the solvent is not particularly limited, but is usually 1 to 40% by mass, and preferably 10 to 30% by mass. The polymerization reaction time can be appropriately selected, but is usually in the range of 2 to 50 hours.

[0033] Furthermore, polymer (A) can be obtained by reacting a polymer (A-1) having repeating units represented by the following formula (G) with a compound represented by the following formula (1B) to obtain repeating units represented by the following formula (1-X) as an example of repeating units represented by formula (1). (In equations (G), (1B), and (1-X), R １ , R ３ and n are, respectively, R in equation (1) １ , R ３ (And is synonymous with n.)

[0034] <Solvent> The solvent used in the protective film-forming composition is not particularly limited as long as it can uniformly dissolve the solid components at room temperature, but organic solvents commonly used in semiconductor lithography process chemicals are preferred. Specifically, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, cyclo Examples include heptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used individually or in combination of two or more.

[0035] Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, and cyclohexanone are preferred. Propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are particularly preferred.

[0036] <Compound (B)> The protective film-forming composition may further contain compound (B) (hereinafter sometimes referred to as "compound (B)") having an aromatic hydrocarbon ring to which at least two hydroxyl groups are bonded, from the viewpoint of chemical resistance. Examples of aromatic hydrocarbon rings include benzene rings and naphthalene rings. Examples of compound (B) include the compound represented by the following formula (1a), the compound represented by the following formula (1b), and the compound represented by the following formula (B). (In equations (1a) and (1b), R １ (where k represents a single bond, an alkylene group with 1 to 4 carbon atoms, or an alkenylene group with 2 to 4 carbon atoms having one or two carbon-carbon double bonds; k represents 0 or 1; m represents an integer from 1 to 3; and n represents an integer from 2 to 4.) (In formula (B), n represents an integer from 2 to 10. When n is 2, X represents a sulfinyl group, a sulfonyl group, an ether group, or a divalent organic group having 2 to 50 carbon atoms. When n is an integer other than 2, X represents an n-valent organic group having 2 to 50 carbon atoms. Y represents a single bond or a divalent linking group having 1 to 12 carbon atoms.)

[0037] Examples of compound (B) include the following compounds.

[0038] << Compound represented by formula (1a), compound represented by formula (1b) below >> (In equations (1a) and (1b), R １ (where k represents a single bond, an alkylene group with 1 to 4 carbon atoms, or an alkenylene group with 2 to 4 carbon atoms having one or two carbon-carbon double bonds; k represents 0 or 1; m represents an integer from 1 to 3; and n represents an integer from 2 to 4.)

[0039] Examples of compounds represented by formula (1a) include those represented by the following formulas (1a-1) to (1a-19).

[0040] Examples of compounds represented by formula (1b) include those represented by the following formulas (1b-1) to (1b-31).

[0041] << Compound represented by formula (B) >> (In formula (B), n represents an integer from 2 to 10. When n is 2, X represents a sulfinyl group, a sulfonyl group, an ether group, or a divalent organic group having 2 to 50 carbon atoms. When n is an integer other than 2, X represents an n-valent organic group having 2 to 50 carbon atoms. Y represents a single bond or a divalent linking group having 1 to 12 carbon atoms.)

[0042] <<<n>>> n represents an integer between 2 and 10, preferably between 2 and 6, more preferably between 2 and 4, and particularly preferably 2 or 3.

[0043] <<<X>>> When n is 2, X represents a sulfinyl group, a sulfonyl group, an ether group, or a divalent (n-valent) organic group with 2 to 50 carbon atoms. When n is an integer other than 2, X represents an n-valent organic group with 2 to 50 carbon atoms.

[0044] An n-valent organic group having 2 to 50 carbon atoms may, for example, be an n-valent organic group having 3 to 10 carbon atoms. Here, n-valent includes divalent. An n-valent organic group having 2 to 50 carbon atoms may, for example, have a ring structure. Examples of ring structures include aromatic hydrocarbon rings, heterocycles, and aliphatic rings. It is preferable that an n-valent organic group having 2 to 50 carbon atoms has at least one of an aromatic hydrocarbon ring and a heterocycle. Examples of aromatic hydrocarbon rings include benzene, naphthalene, anthracene, acenaphthene, fluorene, triphenylene, phenalene, phenanthrene, indene, indane, indacene, pyrene, chrysene, perylene, naphthacene, pentacene, coronene, heptacene, benzo[a]anthracene, dibenzophenanthrene, and dibenzo[a,j]anthracene. Examples of heterocycles include furan, thiophene, pyrrole, imidazole, pyran, pyridine, pyrimidine, pyrazine, pyrrolidine, piperidine, piperazine, morpholine, quinuclidine, indole, purine, thymine, quinoline, isoquinoline, chromene, thiantrene, phenothiazine, phenoxazine, xanthene, acridine, phenazine, carbazole, hydantoin, uracil, barbituric acid, triazine, cyanuric acid, etc. The heterocycle may be a triazinetrione. The ring structure may have substituents. Examples of substituents include a C1-C10 alkyl group which may be interrupted by an oxygen atom or a sulfur atom, an C1-C10 alkenyl group which may be interrupted by an oxygen atom or a sulfur atom, or an alkynyl group which may be interrupted by an oxygen atom or a sulfur atom. The alkyl group, alkenyl group, and alkynyl group may be linear or branched. "May be interrupted" means that any carbon-carbon bond in the alkyl group, alkenyl group, or alkynyl group is interrupted by a heteroatom (i.e., an ether bond in the case of oxygen, or a sulfide bond in the case of sulfur).

[0045] When n is 2, the n-valent organic group having 2 to 50 carbon atoms may be, for example, an alkylene group having 2 to 6 carbon atoms.

[0046] The n-valent organic groups having 2 to 50 carbon atoms may include linear, branched, or cyclic saturated or unsaturated hydrocarbon groups, aromatic groups, heteroaromatic groups, ether groups, hydroxyl groups, ester groups, keto groups, amino groups, halogen groups, sulfide groups, carboxyl groups, sulfo groups, amide groups, imide groups, cyano groups, aldehyde groups, imino groups, urea groups, carbamate groups, carbonate groups, nitro groups, and sulfone groups.

[0047] X is preferably a heterocyclic group with 3 to 10 carbon atoms and a valency of 2 to 5.

[0048] Examples of X include the following groups: (* indicates a link.)

[0049] <<<Y>>> Y represents a single bond or a divalent linking group having 1 to 12 carbon atoms. An example of a divalent linking group having 1 to 12 carbon atoms is the divalent linking group having 1 to 12 carbon atoms represented by the following formula (Y-1). (In formula (Y-1), R １ X represents a single bond or an alkylene group with 1 to 4 carbon atoms. １ R represents a single bond, an ether group, or an ester group. ２ These are alkylene groups with 1 to 8 carbon atoms, phenylene groups, and -(C ｎ H ２ｎ O) ｍ - (n represents 2 or 3; m represents 2 or 3), or -CH ２ -CH(OH)-CH ２ Represents -. X ２ R represents a single bond, an ether group, or an ester group. ３ This represents a single bond, an alkylene group with 1 to 8 carbon atoms, or a group represented by the following formula (Y-1-1). *1 represents the bond with X in formula (B). *2 represents the bond with the benzene ring in formula (B). However, the total number of carbon atoms is 1 to 12. (In formula (Y-1-1), *3 represents a bond that connects to the benzene ring in formula (B). * represents a bond.)

[0050] Examples of the divalent linking group represented by the formula (Y-1) include, for example, the following divalent linking groups.・ (*1) An alkylene group having 1 to 10 carbon atoms (*2)・ (*1) A phenylene group (*2)・ (*1) -C(=O)O- (*2)・ (*1) -OC(=O)O- (*2)・ (*1) -CH ２ OC(=O)-(*2)・ (*1) -CH ２ CH ２ OC(=O)-(*2)・ (*1) -CH ２ CH ２ CH ２ OC(=O)-(*2)・ (*1) -CH(CH ３ )OC(=O)-(*2)・ (*1) -CH ２ CH ２ CH ２ CH ２ OC(=O)-(*2)・ (*1) -CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ OC(=O)-(*2)・ (*1) -OCH ２ CH ２ OC(=O)-(*2)・ (*1) -OCH ２ CH[[ID=​​​​​​​​​​​​​​​​​​​​​２ -CH(OH)-CH ２ -OC(=O)-CH ２ CH ２ -(*2) ・(*1)-CH ２ -CH(OH)-CH ２ -OC(=O)-C(CN)=CH-(*2) ・(*1)-O-CH ２ -CH(OH)-CH ２ -OC(=O)-C(CN)=CH-(*2) ・(*1)-C(=O)O-CH ２ -CH(OH)-CH ２ -OC(=O)-C(CN)=CH-(*2) (*1 and *2 are equivalent to *1 and *2 in equation (Y-1), respectively.)

[0051] Examples of alkylene groups having 1 to 10 carbon atoms include methylene, ethylene, propylene, trimethylene, butylene, isopropylidene, ethylidene, carbonyl, tetramethylene, cyclohexanediyl, and decanediyl groups.

[0052] Examples of compounds represented by formula (B) include the following:

[0053] The following are examples of the synthesis of the compound represented by formula (B). The molecular weight of compound (B) is not particularly limited, but is preferably 100 to 3000, more preferably 150 to 2500, and particularly preferably 200 to 2000 in weight-average molecular weight. In formula (B), when n is 2, X is an ether group, and Y is a single bond, the molecular weight of the compound represented by formula (B) is 236.

[0054] When compound (B) is used, the content of compound (B) is, for example, 0.5% to 20% by mass, preferably 1% to 15% by mass, relative to polymer (A).

[0055] <Curing Catalyst> The curing catalyst (crosslinking catalyst) included as an optional component in the protective film-forming composition can be either a thermal acid generator or a photoacid generator, but it is preferable to use a thermal acid generator.

[0056] Examples of thermal acid generating agents include sulfonic acid compounds and carboxylic acid compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate (pyridinium-p-toluenesulfonic acid), pyridinium phenolsulfonic acid, pyridinium-p-hydroxybenzenesulfonic acid (pyridinium salt of p-phenolsulfonic acid), pyridinium-trifluoromethanesulfonic acid, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, and hydroxybenzoic acid.

[0057] Examples of photoacid generators include onium salt compounds, sulfonimide compounds, and disulfonyldiazomethane compounds.

[0058] Examples of iodonium salt compounds include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoron-butanesulfonate, diphenyliodonium perfluoron-octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoron-butanesulfonate, triphenylsulfonium camphorsulfonate and triphenylsulfonium trifluoromethanesulfonate.

[0059] Examples of sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoron-butanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0060] Examples of disulfonyl diazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0061] Only one type of curing catalyst may be used, or two or more types may be used in combination.

[0062] When a curing catalyst is used, the content of the curing catalyst is, for example, 0.1% to 20% by mass, preferably 1% to 10% by mass, relative to the polymer (A).

[0063] <Crosslinking Agent> From the viewpoint of suitably obtaining the effects of the present invention, it is preferable that the protective film-forming composition does not contain a crosslinking agent. Note that the crosslinking agent is different from polymer (A) and compound (B). Examples of crosslinking agents include melamine-based, substituted urea-based, or compound systems thereof, which have an alkoxymethyl group. Examples of alkoxy groups include alkoxy groups having 1 to 10 carbon atoms, such as methoxy, ethoxy, propoxy, and butoxy groups. Examples of methyl groups having such alkoxy groups include methoxymethyl, ethoxymethyl, propoxymethyl, and butoxymethyl groups. Preferably, the crosslinking agent has at least two crosslinking substituents, and examples include hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4,6-tetrakis(methoxymethyl)glycoluryl (tetramethoxymethylglycoluryl) (POWDERLINK® 1174), 1,3,4,6-tetrakis(butoxymethyl)glycoluryl, 1,3,4,6-tetrakis(hydroxymethyl)glycoluryl, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-tetrakis(butoxymethyl)urea, and 1,1,3,3-tetrakis(methoxymethyl)urea.

[0064] Furthermore, examples of crosslinking agents include those with high heat resistance. Examples of crosslinking agents with high heat resistance include compounds containing crosslinking substituents having aromatic rings (e.g., benzene rings, naphthalene rings) in their molecules.

[0065] Examples of this compound include compounds having a substructure of the following formula (H-1), or polymers or oligomers having repeating units of the following formula (H-2).

[0066] R １１ , R １２ , R １３ , and R １４ These are hydrogen atoms or alkyl groups having 1 to 10 carbon atoms, and examples of these alkyl groups are given above.

[0067] m1 is 1 ≤ m1 ≤ (6 - m2). m2 is 1 ≤ m2 ≤ 5. m3 is 1 ≤ m3 ≤ (4 - m2). m4 is 1 ≤ m4 ≤ 3.

[0068] Examples of compounds, polymers, and oligomers of formulas (H-1) and (H-2) are given below.

[0069] (In the formula, Me represents a methyl group.)

[0070] (In the formula, Me represents a methyl group.)

[0071] The above compounds can be obtained as products of Asahi Organic Chemicals Co., Ltd. and Honshu Chemical Industry Co., Ltd. For example, among the above crosslinking agents, the compound of formula (H-1-23) can be obtained from Honshu Chemical Industry Co., Ltd. under the trade name TMOM-BP. The compound of formula (H-1-20) can be obtained from Asahi Organic Chemicals Co., Ltd. under the trade name TM-BIP-A.

[0072] Furthermore, the crosslinking agent may be a nitrogen-containing compound having 2 to 6 substituents represented by the following formula (1d) that bond to a nitrogen atom in one molecule, as described in International Publication No. 2017 / 187969.

[0073] (In formula (1d), R １ (* represents a methyl or ethyl group. * represents a bond that connects to a nitrogen atom.)

[0074] The nitrogen-containing compound having 2 to 6 substituents represented by formula (1d) in one molecule may be a glycoluryl derivative represented by the following formula (1E).

[0075] (In equation (1E), four R １ Each of these independently represents either a methyl group or an ethyl group, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group.

[0076] Examples of glycoluryl derivatives represented by formula (1E) include compounds represented by the following formulas (1E-1) to (1E-6).

[0077]

[0078] A nitrogen-containing compound having 2 to 6 substituents represented by formula (1d) in one molecule is obtained by reacting a nitrogen-containing compound having 2 to 6 substituents represented by the following formula (2d) that bond to a nitrogen atom in one molecule with at least one compound represented by the following formula (3d).

[0079] (In formula (2d) and formula (3d), R １ R represents a methyl group or an ethyl group. ４ (* represents an alkyl group with 1 to 4 carbon atoms. * represents a bond that connects to a nitrogen atom.)

[0080] The glycoluryl derivative represented by formula (1E) is obtained by reacting a glycoluryl derivative represented by the following formula (2E) with at least one compound represented by formula (3d).

[0081] A nitrogen-containing compound having 2 to 6 substituents represented by formula (2d) in one molecule is, for example, a glycoluryl derivative represented by the following formula (2E).

[0082] (In formula (2E), R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms.

[0083] Examples of glycoluryl derivatives represented by formula (2E) include the compounds represented by formulas (2E-1) to (2E-4) below. Furthermore, examples of compounds represented by formula (3d) include the compounds represented by formulas (3d-1) and (3d-2) below.

[0084]

[0085] With regard to nitrogen-containing compounds having 2 to 6 substituents represented by formula (1d) bonded to a nitrogen atom in one molecule, the full disclosure in WO2017 / 187969 is incorporated herein by reference.

[0086] <Other Ingredients> To further improve the coating properties against surface unevenness and prevent the occurrence of pinholes and striations in the protective film-forming composition, surfactants may be added. Examples of surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; polyoxyethylene / polyoxypropylene block copolymers; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate; and polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monopalmitate. Examples include nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters like polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorine-based surfactants such as F-Top EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd., product name), Megafac F171, F173, R-30, R-40 (manufactured by DIC Corporation, product name), Florard FC430, FC431 (manufactured by Sumitomo 3M Co., Ltd., product name), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd., product name); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of these surfactants added is usually 2.0% by mass or less, preferably 1.0% by mass or less, relative to the total solid content of the protective film-forming composition. These surfactants may be added individually or in combination of two or more types.

[0087] The non-volatile content of the protective film-forming composition, i.e., the components excluding the solvent, is, for example, 0.01% to 10% by mass.

[0088] (Protective film, method for manufacturing a substrate with a protective film, method for manufacturing a substrate with a resist pattern, and method for manufacturing a semiconductor device) The protective film of the present invention is a fired product of a coating film made from a protective film forming composition. The method for manufacturing a substrate with a protective film of the present invention includes the step of applying the protective film forming composition of the present invention onto a semiconductor substrate having steps and firing it to form a protective film.

[0089] The present invention provides a method for manufacturing a resist-patterned substrate, comprising the following steps (1) to (2): Step (1): Applying the protective film-forming composition of the present invention onto a semiconductor substrate and firing it to form a protective film as a resist underlayer film. Step (2): Forming a resist film directly on the protective film or via another layer, and then exposing and developing it to form a resist pattern.

[0090] The present invention relates to a method for manufacturing a semiconductor device, comprising the following processes (A) to (D): Process (A): A process of forming a protective film on a semiconductor substrate on which an inorganic film has been formed on its surface, using the protective film forming composition of the present invention; Process (B): A process of forming a resist pattern on the protective film, either directly or via another layer; Process (C): A process of dry etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film; Process (D): A process of wet etching the inorganic film using a semiconductor wet etching solution, using the dry-etched protective film as a mask.

[0091] Examples of semiconductor substrates to which the protective film-forming composition of the present invention is applied include silicon wafers, germanium wafers, and compound semiconductor wafers such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0092] When using a semiconductor substrate with an inorganic film formed on its surface, the inorganic film is formed by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin coating (spin-on-glass: SOG). Examples of the inorganic film include polysilicon films, silicon oxide films, silicon nitride films, silicon oxynitride films, BPSG (Boro-Phosphoric Acid Glass) films, titanium nitride films, titanium oxynitride films, tungsten nitride films, gallium nitride films, and gallium arsenide films. The semiconductor substrate may also be a stepped substrate with so-called vias (holes), trenches (grooves), etc. formed on it. For example, a via has a roughly circular shape when viewed from above, with a diameter of approximately 2 nm to 20 nm and a depth of 50 nm to 500 nm, while a trench has a width of 2 nm to 20 nm and a depth of 50 nm to 500 nm. Because the protective film-forming composition of the present invention has a small weight-average molecular weight and average particle size of the compounds contained in the composition, it can be embedded in stepped substrates like the one described above without defects such as voids. The absence of defects such as voids is an important characteristic for subsequent processes in semiconductor manufacturing (wet etching / dry etching of semiconductor substrates, resist pattern formation).

[0093] The protective film-forming composition of the present invention is applied to such a semiconductor substrate by an appropriate coating method such as a spinner or coater. Then, a protective film is formed by baking using a heating means such as a hot plate. The baking conditions are appropriately selected from a baking temperature of 100°C to 400°C and a baking time of 0.3 minutes to 60 minutes. Preferably, the baking temperature is 120°C to 350°C and the baking time is 0.5 minutes to 30 minutes; more preferably, the baking temperature is 150°C to 300°C and the baking time is 0.8 minutes to 10 minutes. The thickness of the formed protective film is, for example, 0.001 μm to 10 μm, preferably 0.002 μm to 1 μm, and more preferably 0.005 μm to 0.5 μm. If the baking temperature is lower than the above range, crosslinking may be insufficient, and the formed protective film may not be able to obtain sufficient resistance to resist solvents or basic hydrogen peroxide aqueous solutions. On the other hand, if the baking temperature is higher than the above range, the protective film may decompose due to heat.

[0094] A resist film is formed directly or via another layer on the protective film formed as described above, and then exposed and developed to form a resist pattern. Exposure is performed through a mask (reticle) for forming a predetermined pattern, and for example, i-ray, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet), or EB (electron beam) is used. For development, an alkaline developer is used, and the development temperature is appropriately selected from 5°C to 50°C and the development time from 10 seconds to 300 seconds. As the alkaline developer, aqueous solutions of alkalis such as inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, and cyclic amines such as pyrrole and piperidine can be used. Furthermore, appropriate amounts of alcohols such as isopropyl alcohol and nonionic surfactants can be added to the aqueous solutions of the above alkalis. Among these, preferred developers are quaternary ammonium salts, and more preferably tetramethylammonium hydroxide and choline. Furthermore, surfactants can also be added to these developers. Alternatively, development can be performed using an organic solvent such as butyl acetate instead of an alkaline developer, and the parts of the photoresist where the alkali dissolution rate has not improved can be developed.

[0095] Next, the protective film is dry-etched using the formed resist pattern as a mask. At this time, if the inorganic film is formed on the surface of the semiconductor substrate used, the surface of the inorganic film is exposed; if the inorganic film is not formed on the surface of the semiconductor substrate used, the surface of the semiconductor substrate is exposed.

[0096] Furthermore, the desired pattern is formed by wet etching using a semiconductor wet etching solution, with the protective film after dry etching (and the resist pattern remaining on the protective film, if any) as a mask.

[0097] For semiconductor wet etching solutions, general chemicals used for etching semiconductor wafers can be used, including substances that exhibit both acidic and basic properties.

[0098] Examples of acidic substances include hydrogen peroxide, hydrofluoric acid, ammonium fluoride, acidic ammonium fluoride, ammonium hydrogen fluoride, buffered hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, or mixtures thereof.

[0099] Examples of substances exhibiting basicity include ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, and basic hydrogen peroxide solution obtained by mixing hydrogen peroxide with organic amines such as triethanolamine to make the pH basic. A specific example is SC-1 (ammonia-hydrogen peroxide solution). In addition, substances that can make the pH basic, such as a mixture of urea and hydrogen peroxide solution that generates ammonia by thermal decomposition of urea through heating and ultimately makes the pH basic, can also be used as a chemical solution for wet etching.

[0100] Among these, acidic hydrogen peroxide solution or basic hydrogen peroxide solution is preferred.

[0101] These chemical solutions may contain additives such as surfactants.

[0102] The operating temperature for semiconductor wet etching solutions is preferably 25°C to 90°C, and more preferably 40°C to 80°C. The wet etching time is preferably 0.5 minutes to 30 minutes, and more preferably 1 minute to 20 minutes.

[0103] The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.

[0104] The following describes the equipment used to measure the weight-average molecular weight of the polymers obtained in the synthesis example below. Equipment: Tosoh Corporation HLC-8420GPC GPC column: Shodex® Asahipak® (Showa Denko K.K.) Column temperature: 40°C Flow rate: 0.35 mL / min Eluent: Tetrahydrofuran (THF) Standard sample: Polystyrene (Tosoh Corporation)

[0105] <Synthesis Example 1> A solution of 7.619 g of 2-hydroxy-3-(methacryloyloxy)propyl 3,4-dihydroxybenzoate, 0.381 g of 2,2'-azobis(isobutyrate)dimethyl, and 24.00 g of propylene glycol monomethyl ether was added to a dropwise funnel. This solution was added dropwise to a reaction flask containing 8.00 g of propylene glycol monomethyl ether under a nitrogen atmosphere at an internal temperature of 120°C, and the mixture was heated and stirred for 6 hours. The resulting reaction product was reprecipitated in water, and the precipitate was recovered by decantation. After drying under reduced pressure at 60°C, it was redissolved with 10.00 g of propylene glycol monomethyl ether. The resulting reaction product was a polymer containing repeating units represented by formula (E1-1), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 6192.

[0106] Formula (E1-1)

[0107] <Synthesis Example 2> A solution of 7.619 g of 2-hydroxy-3-(methacryloyloxy)propyl 3,4,5-trihydroxybenzoate, 0.381 g of 2,2'-azobis(isobutyrate)dimethyl, and 24.00 g of propylene glycol monomethyl ether was added to a dropwise funnel. This solution was added dropwise to a reaction flask containing 8.00 g of propylene glycol monomethyl ether under a nitrogen atmosphere at an internal temperature of 120°C, and the mixture was heated and stirred for 6 hours. The resulting reaction product was reprecipitated from water, and the precipitate was recovered by decantation. After drying under reduced pressure at 60°C, it was redissolved with 5.00 g of propylene glycol monomethyl ether. The resulting reaction product was a polymer containing repeating units represented by formula (E1-2), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 5190.

[0108] Formula (E1-2)

[0109] <Synthesis Example 3> A solution of 36.36 g of glycidyl methacrylate, 3.636 g of 2,2'-azobis(isobutyrate)dimethyl, and 93.33 g of propylene glycol monomethyl ether was added to a dropper funnel. This solution was added dropwise to a reaction flask containing 66.67 g of propylene glycol monomethyl ether under a nitrogen atmosphere at an internal temperature of 100°C, and the mixture was heated and stirred for 6 hours. The resulting reaction product was a polymer containing repeating units represented by formula (E1-3) (epoxy value 1.300 eq. / kg), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 4091.

[0110] Formula (E1-3)

[0111] <Synthesis Example 4> 20.00 g of the reaction product obtained in Synthesis Example 3 (18.5 wt% propylene glycol monomethyl ether solution), 4.420 g of gallic acid, 0.330 g of tetrabutylphosphonium bromide, and 17.47 g of propylene glycol monomethyl ether were added to a reaction flask and heated and stirred under a nitrogen atmosphere at an internal temperature of 100°C for 19 hours. The resulting reaction product was a polymer containing repeating units represented by formula (E1-4), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 9691.

[0112] Formula (E1-4)

[0113] <Synthesis Example 5> 20.00 g of the reaction product obtained in Synthesis Example 3 (18.5 wt% propylene glycol monomethyl ether solution), 4.740 g of dihydrocaffeic acid, 0.330 g of tetrabutylphosphonium bromide, and 18.72 g of propylene glycol monomethyl ether were added to a reaction flask and heated and stirred under a nitrogen atmosphere at an internal temperature of 100°C for 19 hours. The resulting reaction product was a polymer containing repeating units represented by formula (E1-5), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 57058.

[0114] Formula (E1-5)

[0115] <Synthesis Example 6> 20.00 g of the reaction product obtained in Synthesis Example 3 (18.5 wt% propylene glycol monomethyl ether solution), 4.370 g of 3,4-dihydroxyphenylacetic acid, 0.330 g of tetrabutylphosphonium bromide, and 17.27 g of propylene glycol monomethyl ether were added to a reaction flask and heated and stirred under a nitrogen atmosphere at an internal temperature of 100°C for 19 hours. The resulting reaction product was a polymer containing repeating units represented by formula (E1-6), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 24046.

[0116] Formula (E1-6)

[0117] <Synthesis Example 7> A solution of 1.92 g of 4-hydroxyphenyl methacrylate, 12.63 g of 2-hydroxyethyl methacrylate, 1.46 g of 2,2'-azobis(isobutyrate)dimethyl, and 48.00 g of propylene glycol monomethyl ether was added to a dropwise funnel. This solution was added dropwise to a reaction flask containing 16.00 g of propylene glycol monomethyl ether under a nitrogen atmosphere at an internal temperature of 120°C, and the mixture was heated and stirred for 6 hours. The resulting reaction product was reprecipitated in heptane, and the resulting precipitate was recovered by decantation, dried under reduced pressure at 60°C, and then redissolved in 40.00 g of propylene glycol monomethyl ether. The resulting reaction product was a polymer containing repeating units represented by formula (E1-7), and its weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 3600.

[0118] Formula (E1-7)

[0119] <Example 1> To 7.365 g of a solution of the reaction product corresponding to formula (E1-1) (solid content 9.31% by weight), 0.034 g of pyridinium-trifluoromethanesulfonate and 4.600 g of propylene glycol monomethyl ether were added as a crosslinking catalyst to prepare a solution of the protective film-forming composition.

[0120] <Example 2> To 3.887 g of a solution of the reaction product corresponding to formula (E1-4) (solid content 17.64% by weight), 0.034 g of pyridinium-trifluoromethanesulfonate and 8.078 g of propylene glycol monomethyl ether were added as a crosslinking catalyst to prepare a solution of the protective film-forming composition.

[0121] <Example 3> To 3.717 g of a solution of the reaction product corresponding to formula (E1-5) (solid content 18.45% by weight), 0.034 g of pyridinium-trifluoromethanesulfonate and 8.249 g of propylene glycol monomethyl ether were added as a crosslinking catalyst to prepare a solution of the protective film-forming composition.

[0122] <Example 4> To 3.743 g of a solution of the reaction product corresponding to formula (E1-6) (solid content 18.32% by weight), 0.034 g of pyridinium-trifluoromethanesulfonate and 8.223 g of propylene glycol monomethyl ether were added as a crosslinking catalyst to prepare a solution of the protective film-forming composition.

[0123] <Example 5> To 3.711 g of a solution of the reaction product corresponding to formula (E1-4) (solid content 17.64% by weight), 0.033 g of pyridinium-trifluoromethanesulfonate as a crosslinking catalyst, 0.033 g of gallic acid as an additive, and 8.224 g of propylene glycol monomethyl ether were added to prepare a solution of the protective film-forming composition.

[0124] <Comparative Example 1> To 4.807 g of a solution (17.2% by weight solids) of the reaction product corresponding to the following formula (E1-8), 0.031 g of pyridinium-trifluoromethanesulfonate as a crosslinking catalyst, 0.041 g of gallic acid as an additive, 0.001 g of surfactant (DIC Corporation, product name: Megafac R-40), and 10.12 g of propylene glycol monomethyl ether were added to prepare a solution of the protective film-forming composition. The reaction product corresponding to formula (E1-8) was synthesized according to Synthesis Example 3 of WO2018 / 203540.

[0125] Formula (E1-8)

[0126] <Comparative Example 2> To 3.869 g of a solution of the reaction product corresponding to formula (E1-7) (solid content 14.8% by weight), 0.029 g of pyridinium-trifluoromethanesulfonate, 5.163 g of propylene glycol monomethyl ether, and 0.940 g of propylene glycol monomethyl ether acetate were added as a crosslinking catalyst to prepare a solution of the protective film-forming composition.

[0127] [Resist Solvent Resistance Test] Each of the protective film-forming compositions prepared in Examples 1 to 5 and Comparative Examples 1 to 2 was applied (spin-coated) onto a silicon wafer using a spin coater. After application, the silicon wafer was heated on a hot plate at 220°C for 1 minute to form a protective film with a thickness of 150 nm. Next, to confirm the resist solvent resistance of the protective film, the silicon wafer after protective film formation was immersed for 1 minute in a solvent mixture of propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a weight ratio of 7:3, and after spin-drying, it was baked at 100°C for 30 seconds. The thickness of the protective film before and after immersion in the mixed solvent was measured using an optical interferometer (product name: NanoSpec 6100, manufactured by Nanometrics Japan Co., Ltd.). The resist solvent resistance was evaluated by calculating and evaluating the percentage reduction in the thickness of the protective film removed by solvent immersion using the following formula. The results are shown in Table 1. Furthermore, a film thickness reduction rate of approximately 1% or less indicates sufficient resistance to resist solvents. Film thickness reduction rate (%) = [(A - B) / A] × 100 A: Film thickness before solvent immersion B: Film thickness after solvent immersion

[0128]

[0129] From the results above, the protective film-forming compositions of Examples 1 to 5 and Comparative Examples 1 to 2 showed very little change in film thickness even after immersion in the resist solvent. Therefore, the protective film-forming compositions of Examples 1 to 5 and Comparative Examples 1 to 2 have sufficient resist solvent resistance to function as protective films.

[0130] [Hydrogen Peroxide Resistance Test] Each of the protective film-forming compositions prepared in Examples 1 to 5 and Comparative Examples 1 to 2 was applied to a TiN-deposited substrate (TiN film thickness: 50 nm) using a spin coater, and a protective film was formed to a thickness of 150 nm by heating at 220°C for 1 minute. Next, the TiN-deposited substrate with the protective film formed was immersed in 20% by weight hydrogen peroxide solution heated to 70°C for 5 minutes, and it was observed whether the protective film peeled off from the substrate. The degree of peeling of the protective film (area of ​​peeling of the protective film) is indicated as "◎" if it is 0-10% of the total area of ​​the protective film, "〇" if it is 11-30%, and "×" if it is 31% or more. The results are shown in Table 2.

[0131]

[0132] The results above demonstrate that, compared to Comparative Example 1, the protective film of Examples 1 to 5 is less likely to peel off from the substrate when exposed to acidic hydrogen peroxide. Furthermore, compared to Comparative Example 2, the protective film of Examples 1 to 5 is less likely to deteriorate when exposed to acidic hydrogen peroxide. In other words, Examples 1 to 5 show better chemical resistance to acidic hydrogen peroxide than Comparative Examples 1 to 2, and are useful as protective films against acidic hydrogen peroxide.

[0133] [Resistance Test to Basic Hydrogen Peroxide Solution] Each of the protective film-forming compositions prepared in Examples 1 to 5 and Comparative Example 2 was applied to a TiN-deposited substrate (TiN film thickness: 50 nm) using a spin coater, and a protective film was formed to a thickness of 150 nm by heating at 220°C for 1 minute. Next, 28% ammonia water, 33% hydrogen peroxide, and water were mixed in a weight ratio of 1:4:20 to prepare basic hydrogen peroxide solution. Then, the TiN-deposited substrate with the protective film formed on it was immersed in basic hydrogen peroxide solution heated to 50°C for 120 seconds, and it was observed whether the protective film peeled off from the substrate. The degree of peeling of the protective film (area of ​​peeling of the protective film) is indicated as "◎" if it is 0-10% of the total area of ​​the protective film, "〇" if it is 11-30%, and "×" if it is 31% or more. The results are shown in Table 3.

[0134]

[0135] The results above demonstrate that, compared to Comparative Example 2, the protective film of Examples 1 to 5 is less likely to peel off the substrate when exposed to basic hydrogen peroxide. In other words, Examples 1 to 5 show better chemical resistance to basic hydrogen peroxide than Comparative Example 2 and are useful as protective films against basic hydrogen peroxide.

[0136] According to the present invention, a composition can be provided for forming a protective film with excellent resistance to semiconductor wet etching solutions using hydrogen peroxide in a lithography process in semiconductor manufacturing.

Claims

1. A protective film-forming composition comprising a polymer having repeating units represented by the following formula (1) and a solvent, wherein the content of the polymer is 80% by mass or more relative to the nonvolatile content of the protective film-forming composition. (In formula (1), R １ R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ This is a single bond, or -CH ２ Represents -. R ３ X represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. １ This represents -O- or -NH-. １ represents -NH-, -S-, -C(=O)-O-, or -O-C(=O)-. n represents an integer between 2 and 5.

2. The composition for forming a protective film according to claim 1, wherein the repeating unit represented by the formula (1) is a repeating unit represented by the following formula (1-1). (In the formula (1-1), R １ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ２ represents a single bond or -CH ２ -. R ３ represents a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms. X １ represents -O- or -NH-. Y １ represents -NH-, -S-, -C(=O)-O- or -O-C(=O)-. n represents an integer of 2 to 5.) 3. The protective film-forming composition according to claim 1, wherein the molar proportion of the repeating unit represented by formula (1) is 80 mol% or more with respect to the total repeating units of the polymer.

4. A protective film-forming composition according to claim 1, which does not contain a crosslinking agent.

5. The protective film-forming composition according to claim 1, comprising a curing catalyst.

6. The protective film forming composition according to claim 1, which is a protective film forming composition for forming a protective film that protects the inorganic film on a semiconductor substrate having an inorganic film formed on its surface from wet etching.

7. A protective film for semiconductor wet etching solutions, which is a fired product of a coating film made from the protective film-forming composition according to any one of claims 1 to 6.

8. A method for manufacturing a substrate with a protective film, comprising the step of applying a protective film-forming composition according to any one of claims 1 to 6 onto a semiconductor substrate having steps and firing it to form a protective film.

9. A method for manufacturing a substrate with a resist pattern, used in the manufacture of a semiconductor, comprising the steps of: applying a protective film-forming composition according to any one of claims 1 to 6 onto a semiconductor substrate and firing it to form a protective film as a resist underlayer film; and forming a resist film directly on the protective film or via another layer, and then exposing and developing it to form a resist pattern.

10. A method for manufacturing a semiconductor device, comprising the steps of: forming a protective film on a semiconductor substrate having an inorganic film formed on its surface using a protective film forming composition according to any one of claims 1 to 6; forming a resist pattern on the protective film directly or via another layer; dry etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film; and wet etching the inorganic film using a semiconductor wet etching solution, using the dry-etched protective film as a mask.

Images