Pattern forming method using protective film-forming composition containing specific crosslinking agent

Abstract

To provide a protective film-forming composition against a basic aqueous hydrogen peroxide solution.SOLUTION: A protective film-forming composition against a basic aqueous hydrogen peroxide solution comprises: a cross-linking agent having, in a molecule, two or more of at least one group selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, an epoxycyclohexyl group, an oxetanyl group, a vinyl ether group, an isocyanate group, and a blocked isocyanate group; a compound having a group represented by the following formula (1) in a side chain or at a terminal and having a weight average molecular weight of 800 or more; and an organic solvent. (In the formula, X1 represents a substituent which reacts with the cross-linking agent; R0 represents a direct bond or a C1-2 alkylene group; X2 represents a C1-2 alkyl group, a C1-2 alkoxy group, or a fluoro group; a represents an integer of 0-2; b represents an integer of 1-3; and b and c satisfy a relational expression, 1≤(b+c)≤5.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a protective film that has excellent resistance to a basic aqueous hydrogen peroxide solution in a lithography process, and to a method for forming a pattern by applying the protective film. [Background technology]

[0002] A lithography process is known in which a resist underlayer film is provided between a substrate and a resist film formed thereon to form a resist pattern of a desired shape. However, conventional resist underlayer films, such as those formed from a composition containing an aminoplast-based crosslinking agent as described in Patent Document 1, have poor resistance to a basic hydrogen peroxide aqueous solution. Therefore, such resist underlayer films could not be used as a mask in an etching process using a basic hydrogen peroxide aqueous solution.

[0003] Patent Document 2 listed below describes an underlayer film-forming composition for lithography containing a compound having a protected carboxyl group, a compound having a group reactive with a carboxyl group, and a solvent, or a compound having a group reactive with a carboxyl group and a protected carboxyl group, and a solvent, and the composition does not contain an aminoplast crosslinking agent as an essential component. However, Patent Document 2 does not describe or suggest anything about the resistance of a resist underlayer film formed from the composition to a basic hydrogen peroxide aqueous solution.

[0004] Patent Document 3 below describes a pattern formation method using a resist underlayer film that is resistant to a basic hydrogen peroxide aqueous solution. The composition for forming the resist underlayer film contains a polymer having an epoxy group and a weight-average molecular weight of 1,000 to 100,000, and a solvent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4145972 [Patent Document 2] International Publication No. 2005 / 013601 [Patent Document 3] International Publication No. 2015 / 030060 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been an increasing demand for protective films that have improved resistance to basic hydrogen peroxide aqueous solutions. An object of the present invention is to provide a novel composition for forming a protective film that is resistant to basic hydrogen peroxide aqueous solutions, and a pattern formation method using the protective film. [Means for solving the problem]

[0007] The inventors of the present invention have found a combination of a specific crosslinking agent other than aminoplast-based crosslinking agents and a compound having a weight-average molecular weight of 800 or more and containing a substituent reactive with the specific crosslinking agent, thereby solving the above-mentioned problems. That is, a first aspect of the present invention relates to a composition comprising a crosslinking agent having two or more groups in one molecule of at least one type selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, an epoxycyclohexyl group, an oxetanyl group, a vinyl ether group, an isocyanate group, and a blocked isocyanate group, a compound having a group represented by the following formula (1) in a side chain or at a terminal and having a weight-average molecular weight of 800 or more, and an organic solvent: The present invention relates to a protective film-forming composition for a basic hydrogen peroxide aqueous solution. [ka] (In the formula, X 1 represents a substituent that reacts with the crosslinking agent, and R 0 represents a direct bond or an alkylene group having 1 or 2 carbon atoms; X 2represents an alkyl group having 1 or 2 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a fluoro group; a represents an integer of 0 to 2; b represents an integer of 1 to 3; when b represents 2 or 3, -R 0 -X 1 may be different from each other, c represents an integer of 0 to 4, and when c represents 2, 3 or 4, X 2 The groups represented by may be different from each other, and b and c satisfy the relationship 1≦(b+c)≦5.)

[0008] The protective film-forming composition may contain a compound having a group represented by the following formula (2) on a side chain or at a terminal and having a weight average molecular weight of 800 or more, instead of the compound having a group represented by formula (1) on a side chain or at a terminal and having a weight average molecular weight of 800 or more. [ka] (In the formula, R 1 represents a direct bond or a linear or branched alkylene group having 1 to 8 carbon atoms; X 1 represents a substituent that reacts with the crosslinking agent.

[0009] Substituent X reacts with the crosslinking agent 1 represents a group that reacts directly with a crosslinking agent or a group containing a group that reacts directly with a crosslinking agent. The group that reacts directly with a crosslinking agent may also include a group that has a protecting group and reacts with a crosslinking agent by removing the protecting group. Substituent X reacts with the crosslinking agent 1 is, for example, a group represented by the following formula (3), formula (4), formula (5), formula (6), formula (7), formula (8), formula (9), formula (10) or formula (11). [ka] (In the formula, R 2 represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms; R 3 represents a hydrogen atom or a linear, branched or cyclic hydrocarbon group having 1 to 8 carbon atoms, and e represents 0 or 1.

[0010] Substituent X reacts with the crosslinking agent 1 is preferably the formula (3), Equation (4), It is a group represented by formula (5) or formula (6).

[0011] The amount of the crosslinking agent added is determined, for example, by adjusting the amount of the substituent X that reacts with the crosslinking agent in the compound having a weight average molecular weight of 800 or more. 1 When all of the substituents are taken as 100 mol %, the substituent X 1 The amount is such that 20 mol % to 150 mol % of the crosslinking agent can be blocked. The crosslinking agent preferably has two or more glycidyl groups, terminal epoxy groups, or epoxycyclohexyl groups in one molecule.

[0012] The blocked isocyanate group is, for example, a group represented by the following formula (12) or formula (13). [ka] (In the formula, R 4 and R 5 each independently represents an alkyl group having 1 to 5 carbon atoms; R 6 represents an alkyl group having 1 to 5 carbon atoms, d represents an integer of 1 to 3, and when d represents 2 or 3, R 6 The alkyl groups having 1 to 5 carbon atoms represented by the formula (I) may be different from each other.

[0013] The protective film-forming composition of the present invention may further contain a crosslinking catalyst. The protective film-forming composition of the present invention may further contain a surfactant.

[0014] In a second aspect of the present invention, a protective film is formed on a semiconductor substrate on the surface of which an inorganic film may be formed using the protective film-forming composition for a basic hydrogen peroxide aqueous solution of the first aspect of the present invention, a resist pattern is formed on the protective film, and the protective film is dry-etched using the resist pattern as a mask to expose the inorganic film or the surface of the semiconductor substrate, The pattern forming method further comprises wet etching and cleaning the inorganic film or the semiconductor substrate using the protective film after etching as a mask with a basic aqueous hydrogen peroxide solution.

[0015] The basic hydrogen peroxide aqueous solution contains, for example, ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, triethanolamine, or urea. When the basic hydrogen peroxide aqueous solution contains ammonia, the basic hydrogen peroxide aqueous solution is, for example, a mixture of a 25% to 30% by mass aqueous ammonia solution (A), a 30% to 36% by mass aqueous hydrogen peroxide solution (B), and water (C), where the volume ratio of the aqueous hydrogen peroxide solution (B) to the aqueous ammonia solution (A): (B) / (A) is, for example, 0.1 to 20.0, and the volume ratio of the water (C) to the aqueous ammonia solution (A): (C) / (A) is, for example, 1.0 to 50.0. [Effects of the Invention]

[0016] The protective film formed from the protective film-forming composition of the present invention is resistant to a basic aqueous hydrogen peroxide solution. In particular, a protective film formed from a protective film-forming composition using a crosslinker having two or more glycidyl groups, terminal epoxy groups, or epoxycyclohexyl groups per molecule has excellent resistance to a basic aqueous hydrogen peroxide solution. Therefore, the protective film formed from the protective film-forming composition of the present invention can be used as a mask in an etching process or a cleaning process using a basic aqueous hydrogen peroxide solution. DETAILED DESCRIPTION OF THE INVENTION

[0017] The components contained in the protective film-forming composition of the present invention will be described in detail below.

[0018] [Compounds with a weight-average molecular weight of 800 or more] The protective film-forming composition of the present invention contains a compound having a group represented by formula (1) or a group represented by formula (2) at a side chain or terminal thereof and having a weight-average molecular weight of 800 or more. The weight-average molecular weight of the compound is a value obtained by gel permeation chromatography (GPC) using polystyrene as a standard sample. The upper limit of the weight-average molecular weight is, for example, 500,000. The compound having a weight-average molecular weight of 800 or more is not limited to a polymer, but may be one or a mixture of two or more selected from the group consisting of a monomer, a dimer, a trimer, and an oligomer. The polymer may be either a copolymer or a homopolymer.

[0019] Examples of the group represented by formula (1) include groups represented by the following formulae (1-1) to (1-111). [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0020] Examples of the group represented by formula (2) include groups represented by the following formulae (2-1) to (2-28). [ka] [ka]

[0021] The compound having a weight-average molecular weight of 800 or more may further have an absorbing moiety having absorption at a wavelength of 193 nm or an absorbing moiety having absorption at a wavelength of 248 nm. Examples of the absorbing moiety having absorption at a wavelength of 193 nm include a benzene ring, a naphthalene ring, a triazine ring, and an isocyanuric ring, and examples of the absorbing moiety having absorption at a wavelength of 248 nm include a naphthalene ring, an anthracene ring, and a triazine ring.

[0022] [Crosslinking agent] The protective film-forming composition of the present invention comprises End groups having epoxy groups (e.g., glycidyl group 、 The crosslinking agent includes a crosslinking agent having two or more groups per molecule of at least one type selected from the group consisting of an epoxycyclopentyl group, an epoxycyclohexyl group, an oxetanyl group, a vinyl ether group, an isocyanate group, and a blocked isocyanate group. The crosslinking agent may have two or more groups of one type per molecule, or may have, for example, one of each of two types of groups per molecule (two in total). Hereinafter, the "terminal group having an epoxy group" may be referred to as a "terminal epoxy group".

[0023] Examples of compounds having two or more groups per molecule that are at least one type selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, and an epoxycyclohexyl group include tris(2,3-epoxypropyl)isocyanurate, 1,4-butanediol diglycidyl ether, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, 1,2-cyclohexanedicarboxylate diglycidyl, 1,2-epoxy-4-(epoxyethyl)cyclohexane, 4,4'-methylenebis[N,N-bis(oxiranylmethyl)aniline], trimethylolpropane triglycidyl ether, bisphenol-A diglycidyl ether, and TEPIC (registered trademark)-L, TEPIC-SS, TEPIC-PAS B26L, and TEPIC-PAS manufactured by Nissan Chemical Industries, Ltd. B22, TEPIC-VL, TEPIC-UC, Daicel Corporation's Epofriend AT501, CT301, Celoxide (registered trademark) 2021, 2081, 8000, Epolead (registered trademark) GT-401, PB3600, PB4700, EHPE 3150, EHPE3150CE, Mitsubishi Chemical Corporation's 152, 154, 157S70, 168V70, 604, 630, 801N, 801PN, 802, 806, 807, 811, 813, 816A, 816C, 819, 825, 827, 828, 828EL, 828US, 828XA, 834X90, 871, 872, 1001, 1002, 1003, 1004, 1007, 1009, 1010, 1031S, 1032H60, 1256, 4004P, 4005P, 4007P, 4010P, 4250, 4275, 5046B80, YL980, YL983U, YL6810, YL6121L, YX4000, YX4000H, YX8000, YX8034, YX8800, Nippon Kayaku NC-3000, NC-3000-L, NC-3000-H, NC-3000-FH-75M, NC-3100, CER-30 manufactured by Co., Ltd. 00-L, NC-2000―L, XD-1000, NC-7000L, NC-7300L, EPPN-501H, EPPN-501HY, EPPN-502H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPP N201, BREN-S, BREN-105, GAN, GOT, RE-3035-L, RE-310S, Denacol (registered trademark) EX-211, EX-212, EX-252, EX-810, EX-811, EX-850, EX-851, EX-821, EX-830, EX-832, EX-841, EX-861, EX-911, EX-941, EX-920, EX-931, EX-313, EX-314, EX-321, EX-411, EX-421, EX-512, and EX-612, EX-614, CY175, CY177, CY179, CY182, CY184, and CY192 manufactured by BASF Japan Ltd., and Epiclon 840, 804-S, 850, 850-S, 850-CRP, 850-LC, 860, 1050, 1055, 3050, 4050, 7050, AM-020-P, AM-040-P, HM-091, HM-101, 830, 830-S, EXA-830LVP, 835, EXA-835LV, 1051-75M, and 7070-40K manufactured by DIC Corporation.HM-091-40AX, 152, 153, 153-60T, 153-60M, 1121N-80M, 1123P-75M, N-660, N-665 , N-670, N-673, N-680, N-695, N-655-EXP-S, N-662-EXP-S, N-665-EXP, N-672-EXP, N-670-EXP-S, N-685-EXP-S, N-673-80M, N-680-75M, N-690-75M, N-740, N-770, N-7 75, N-865, HP-4032, HP-4032D, HP-4700, HP-4710, HP-4770, HP-5000, HP-7200, HP -7200H, HP-820, 5500, 5800, MA-DGIC, DAG-G, TG-G manufactured by Shikoku Kasei Co., Ltd., Epotohto (registered trademark) YD-127, YD-128, YDF-170, YD-8125, YDF-8170C, ZX-1059, YD-825GS, YD-825GSH, and Epotohto (registered trademark) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. Examples include YDF-870GS, YDPN-138, YDCN-700, YDC-1312, YSLV-80XY, YSLV-120TE, ST-3000, ST-4000D, YD-171, YH-434, YH-434L, FX-289BEK75, FX-305EK70, and ERF-001M30.

[0024] In addition, a polymer can also be used as a compound having two or more groups in one molecule, each of which is at least one type of group selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, and an epoxycyclohexyl group. The polymer can be used without any particular limitation, as long as it has two or more groups in one molecule, each of which is at least one type of group selected from the group consisting of a glycidyl group, a terminal epoxy group, an epoxycyclopentyl group, and an epoxycyclohexyl group. Such a polymer can be produced by addition polymerization using an addition-polymerizable monomer having an epoxy group, or by reaction of a polymer compound having a hydroxyl group with a compound having an epoxy group, such as epichlorohydrin or glycidyl tosylate. Examples of such polymers include addition polymerization polymers such as polyglycidyl acrylate, copolymers of glycidyl methacrylate and ethyl methacrylate, and copolymers of glycidyl methacrylate, styrene, and 2-hydroxyethyl methacrylate, and condensation polymerization polymers such as epoxy novolac. The weight-average molecular weight of such polymers is, for example, 1,000 to 200,000.

[0025] Examples of compounds having two or more oxetanyl groups in one molecule include (7-oxabicyclo[4.1.0]heptane)-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate and Aron Oxetane (registered trademark) OXT-121 and OXT-221 manufactured by Toagosei Co., Ltd.

[0026] In addition, a polymer can also be used as a compound having two or more oxetanyl groups in one molecule. The polymer can be used without any particular limitation as long as it has two or more oxetanyl groups in one molecule. Such a polymer can be produced by addition polymerization using an addition-polymerizable monomer having an oxetanyl group. The weight-average molecular weight of the polymer is, for example, 1,000 to 200,000.

[0027] Examples of compounds having two or more vinyl ether groups in one molecule include 1,3,5-tris(4-vinyloxybutyl) trimellitate and bis(4-vinyloxybutyl)isophthalate.

[0028] In addition, a polymer can also be used as a compound having two or more vinyl ether groups in one molecule. The polymer can be used without any particular limitation as long as it has two or more vinyl ether groups in one molecule. Such a polymer can be produced by addition polymerization using an addition-polymerizable monomer having a vinyl ether group. The weight-average molecular weight of the polymer is, for example, 1,000 to 200,000.

[0029] Examples of compounds having two or more isocyanate groups in one molecule include Burnock (registered trademark) D-750, D-800, DN-920, DN-950, DN-955, DN-980, and DN-981, all manufactured by DIC Corporation, and Takenate (registered trademark) 500, 600, D-110N, D-120N, D-140N, D-165N, D-170N, and D-177N, all manufactured by Mitsui Chemicals, Inc.

[0030] In addition, a polymer can also be used as a compound having two or more isocyanate groups in one molecule. The polymer can be used without any particular limitation as long as it has two or more isocyanate groups in one molecule. Such a polymer can be produced by addition polymerization using an addition-polymerizable monomer having an isocyanate group. The weight-average molecular weight of the polymer is, for example, 1,000 to 200,000.

[0031] Examples of compounds having two or more blocked isocyanate groups per molecule include Takenate (registered trademark) B-815N, B-830, B-842N, B-870N, B-874N, B-882N, B-7005, B-7030, B-7075, and B-5010, all manufactured by Mitsui Chemicals, Inc.; VESTAGON (registered trademark) B1065, B1400, and B1530, all manufactured by Evonik; and VESTANAT (registered trademark) B1358 / 100, B1370, EP-DS1076, and EP-DS1205, all manufactured by Evonik.

[0032] In addition, polymers containing two or more blocked isocyanate groups in one molecule are also available. The polymer can be any polymer having two or more blocked isocyanate groups in one molecule without any particular limitations. Such a polymer can be produced by addition polymerization using an addition-polymerizable monomer having a blocked isocyanate group. The weight-average molecular weight of the polymer is, for example, 1,000 to 200,000.

[0033] The amount of the crosslinking agent added is determined, for example, by adjusting the amount of the substituent X that reacts with the crosslinking agent in the compound having a weight average molecular weight of 800 or more. 1 When all of the substituents are taken as 100 mol %, the substituent X 1 The amount of the crosslinking agent in the protective film-forming composition of the present invention is an amount capable of sealing 20 mol % to 150 mol %, preferably 40 mol % to 140 mol %, and more preferably 60 mol % to 120 mol % of the total. If the content of the crosslinking agent in the protective film-forming composition of the present invention is too low or excessive, the formed protective film may not be able to achieve resistance to a resist solvent or a basic hydrogen peroxide aqueous solution.

[0034] [Crosslinking catalyst] The protective film-forming composition of the present invention may contain, as an optional component, a crosslinking catalyst to promote the crosslinking reaction. The crosslinking catalyst may be an acidic compound, a basic compound, or a compound that generates an acid or a base upon heating. The acidic compound may be a sulfonic acid compound or a carboxylic acid compound, and the compound that generates an acid upon heating may be a thermal acid generator. Examples of sulfonic acid compounds or carboxylic acid compounds include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, pyridinium-4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, 4-nitrobenzenesulfonic acid, citric acid, benzoic acid, and hydroxybenzoic acid. Examples of thermal acid generators include K-PURE (registered trademark) CXC-1612, CXC-1614, TAG-2172, TAG-2179, TAG-2678, and TAG2689 (all manufactured by King Industries), and SI-45, SI-60, SI-80, SI-100, SI-110, and SI-150 (all manufactured by Sanshin Chemical Industry Co., Ltd.). These crosslinking catalysts can be used alone or in combination of two or more. As the basic compound, an amine compound or an ammonium hydroxide compound can be used, and as the compound that generates a base by heat, urea can be used. Examples of amine compounds include tertiary amines such as triethanolamine, tributanolamine, trimethylamine, triethylamine, tri-normal propylamine, triisopropylamine, tri-normal butylamine, tri-tert-butylamine, tri-normal octylamine, triisopropanolamine, phenyldiethanolamine, stearyldiethanolamine, and diazabicyclooctane, and aromatic amines such as pyridine and 4-dimethylaminopyridine. Other examples of amine compounds include primary amines such as benzylamine and normal butylamine, and secondary amines such as diethylamine and di-normal butylamine. These amine compounds can be used alone or in combination. Examples of ammonium hydroxide compounds include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, cetyltrimethylammonium hydroxide, phenyltrimethylammonium hydroxide, and phenyltriethylammonium hydroxide. As the compound that generates a base by heat, for example, a compound having a heat-labile group such as an amide group, a urethane group, or an aziridine group, and that generates an amine by heating can be used. Examples of compounds that generate a base when heated include triethylammonium chloride, benzyldimethylphenylammonium chloride, benzyldodecyldimethylammonium chloride, benzyltributylammonium chloride, and choline chloride. When the protective film-forming composition contains a crosslinking catalyst, the content thereof is, for example, 0.2% by mass to 20% by mass relative to the content of the compound having a weight average molecular weight of 800 or more contained in the protective film-forming composition.

[0035] [Other ingredients] The protective film-forming composition of the present invention may contain a surfactant as an optional component to improve its coatability on semiconductor substrates. Examples of the surfactant 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 octylphenyl ether and polyoxyethylene nonylphenyl ether; polyoxyethylene-polyoxypropylene block copolymers; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monostearate; Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; F-Top (registered trademark) EF301, EF303, and EF352 (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.); Megafac (registered trademark) F171, F173, R-30, R-30N, R-40, and R-40 Examples of suitable surfactants include fluorine-based surfactants such as Fluorad FC-LM (manufactured by DIC Corporation), Fluorad FC430 and FC431 (manufactured by Sumitomo 3M Limited), Asahiguard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by Asahi Glass Co., Ltd.), and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants can be used alone or in combination of two or more. When the protective film-forming composition contains a surfactant, the content thereof is, for example, 0.01 to 10% by mass relative to the content of the compound having a weight-average molecular weight of 800 or more contained in the protective film-forming composition.

[0036] The protective film-forming composition of the present invention can be prepared by dissolving the above-mentioned components in an organic solvent, and is used in the form of a homogeneous solution. Examples of the organic solvent include 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 monoethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. Examples of the solvent include cyclopentane, cycloheptanone, 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 alone or in combination of two or more.

[0037] The prepared protective film-forming composition is passed through a filter having a pore size of, for example, 0.2 μm or 0.1 μm and It is preferable to use the solution after filtering it using a 0.01 μm filter.

[0038] The pattern forming method using the protective film-forming composition of the present invention will be described below.

[0039] Examples of semiconductor substrates to which the protective film-forming composition of the present invention can be applied include silicon wafers, germanium wafers, and wafers of compound semiconductors such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride. When a semiconductor substrate having an inorganic film formed on its surface is used, the inorganic film can be 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 film, silicon oxide film, silicon nitride film, BPSG (Boro-Phospho Silicate Glass) film, titanium nitride film, titanium nitride oxide film, tungsten film, gallium nitride film, and gallium arsenide film.

[0040] The protective film-forming composition of the present invention is applied to such a semiconductor substrate using an appropriate application method such as a spinner or coater. A protective film is then formed by baking using a heating means such as a hot plate. Baking conditions are appropriately selected from a baking temperature of 100°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 120°C to 350°C and the baking time is 0.5 to 30 minutes, more preferably, the baking temperature is 150°C to 300°C and the baking time is 0.8 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 resistant 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 be thermally decomposed.

[0041] Next, a resist pattern is formed on the protective film. The formation of the resist pattern can be achieved by a conventional method, i.e., by applying a photoresist solution to the protective film, pre-baking, exposure, post-exposure baking (abbreviated as PEB) (if necessary), development, and rinsing. The photoresist solution used to form the resist pattern is not particularly limited as long as it is sensitive to the light used for exposure, and a positive-type photoresist can be used. Examples of suitable photoresists include chemically amplified photoresists consisting of a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate and a photoacid generator; chemically amplified photoresists consisting of a low-molecular-weight compound that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; chemically amplified photoresists consisting of a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate, a low-molecular-weight compound that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator; and DNQ-novolac-type non-chemically amplified photoresists that utilize the difference in alkaline dissolution rate between exposed and unexposed areas. Examples include PAR710, a product of Sumitomo Chemical Co., Ltd., TDUR-P3435LP and THMR-iP1800, a product of Tokyo Ohka Kogyo Co., Ltd., and SEPR430, a product of Shin-Etsu Chemical Co., Ltd. A negative photoresist can also be used instead of a positive photoresist.

[0042] The exposure is carried out through a mask (reticle) for forming a predetermined pattern, and for example, i-rays, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet) or EB (electron beam) are used. An alkaline developer is used for the development, and the development temperature is appropriately selected from 5°C to 50°C and the development time is appropriately selected from 10 seconds to 300 seconds. Examples of the alkaline developer include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, aqueous solutions of ethanolamine, propylamine, ethylenediamine, etc. Examples of the developer include an aqueous alkaline solution such as an aqueous amine solution such as butyl acetate. Furthermore, a surfactant or the like can be added to these developers. A method can also be used in which development is carried out with an organic solvent such as butyl acetate instead of an alkaline developer, and the parts of the photoresist where the alkaline dissolution rate is not improved are developed.

[0043] Next, the protective film is dry-etched using the formed resist pattern as a mask, to expose the surface of the inorganic film if the inorganic film is formed on the surface of the semiconductor substrate used, or to expose the surface of the semiconductor substrate if the inorganic film is not formed on the surface of the semiconductor substrate used.

[0044] Furthermore, a desired pattern can be formed by wet etching using a basic hydrogen peroxide solution, using the protective film (and, if a resist pattern remains on the protective film) after dry etching as a mask. Examples of wet etching chemicals include basic hydrogen peroxide solution, which is obtained by mixing a basic substance, such as ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, or an organic amine such as triethanolamine, with hydrogen peroxide solution to achieve a basic pH. Other wet etching chemicals that can achieve a basic pH include those that mix urea with hydrogen peroxide solution and heat the urea to generate ammonia through thermal decomposition, ultimately achieving a basic pH. The basic hydrogen peroxide solution is preferably used at a temperature of 25°C to 90°C, more preferably 40°C to 80°C. The wet etching time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes. [Example]

[0045] The apparatus used to measure the weight-average molecular weight of the polymers obtained in the following synthesis examples is shown below. Apparatus: Tosoh Corporation HLC-8220GPC GPC column: Shodex (registered trademark) KF-803L, KF-802, KF-801 Column temperature: 40℃ Flow rate: 0.2mL / min Eluent:THF Standard sample: Polystyrene (Tosoh Corporation)

[0046] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the description of the following examples. Furthermore, although the chemical solutions having the compositions shown in Table 1 or Table 3 below were used as the basic hydrogen peroxide aqueous solution, the basic hydrogen peroxide aqueous solution applicable to the present invention is not limited to these compositions.

[0047] <Synthesis Example 1> 40.60 g of propylene glycol was added to 100 g of a 10% solids solution (manufactured by LANCASTER) of p-vinylphenol monomer dissolved in propylene glycol. 25 g of methyl methacrylate (manufactured by Junsei Chemical Co., Ltd.) was dissolved in the solution, and nitrogen was then purged into the reaction solution for 30 minutes. While maintaining the reaction solution at 70°C, 1.32 g of azobisisobutyronitrile (manufactured by Junsei Chemical Co., Ltd.) dissolved in 40 g of propylene glycol was added and stirred under a nitrogen atmosphere. The reaction product was reprecipitated in 1 L of distilled water. The resulting precipitate was filtered and dried to obtain a powder of a polymer having a structural unit represented by the following formula (1A). GPC analysis of the resulting polymer revealed a weight-average molecular weight of approximately 5000 in terms of standard polystyrene. The resulting polymer structure was a copolymer of p-vinylphenol and methyl methacrylate in a molar ratio of 25:75. [ka]

[0048] <Synthesis Example 2> A solution containing 10 g of tris-(2,3-epoxypropyl)-isocyanurate (Nissan Chemical Industries, Ltd., product name: TEPIC-SS), 20.50 g of 3,7-dihydroxy-2-naphthoic acid (Tokyo Chemical Industry Co., Ltd.), 0.90 g of ethyltriphenylphosphonium bromide (ACROSS Corporation), and 73.27 g of propylene glycol monomethyl ether was heated to 120°C and reacted for 24 hours in a nitrogen atmosphere to obtain a solution containing a compound represented by the following formula (1B). GPC analysis of the solution containing the obtained compound revealed that the weight-average molecular weight, calculated as standard polystyrene, was approximately 1000. [ka]

[0049] <Synthesis Example 3> A solution containing 10 g of tris-(2,3-epoxypropyl)-isocyanurate (Nissan Chemical Industries, Ltd., product name: TEPIC-SS), 15.63 g of 2,5-dihydroxybenzoic acid (Tokyo Chemical Industry Co., Ltd.), 0.902 g of ethyltriphenylphosphonium bromide (ACROSS Corporation), and 61.90 g of propylene glycol monomethyl ether was heated to 120°C and reacted for 24 hours in a nitrogen atmosphere to obtain a solution containing a compound represented by the following formula (1C). GPC analysis of the solution containing the obtained compound revealed that the weight-average molecular weight, calculated as standard polystyrene, was approximately 1000. [ka]

[0050] Example 1 To 0.50 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, and 0.30 g of blocked isocyanate resin (manufactured by Evonik Japan Co., Ltd., trade name: VESTANAT [registered trademark] B1358 / 100) were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition. GPC analysis of the polyparahydroxystyrene revealed that the weight-average molecular weight, calculated as standard polystyrene, was approximately 11,000.

[0051] <Example 2> 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, and 0.30 g of 1,3,5-tris(4-vinyloxybutyl) trimellitate were added to 0.50 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000) to form a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0052] Example 3 To 0.49 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.29 g of butanetetracarboxylic acid tetra(3,4-epoxycyclohexylmethyl)-modified ε-caprolactone (manufactured by Daicel Corporation, trade name: Epolead (registered trademark) GT-401), and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0053] Example 4 To 0.60 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.18 g of tris(4,5-epoxypentyl)isocyanurate (manufactured by Nissan Chemical Industries, Ltd., trade name: TEPIC (registered trademark)-VL), and 0.02 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0054] <Example 5> 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, and 0.47 g of 1,3,5-tris(4-vinyloxybutyl) trimellitate were added to 0.33 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000) to form a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0055] Example 6 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, and 0.37 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. were added to 0.43 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000) to prepare a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition. .

[0056] Example 7 A solution was prepared by adding 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, and 0.35 g of TG-G manufactured by Shikoku Kasei Co., Ltd. to 0.45 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000). The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0057] Example 8 A solution was prepared by adding 5.76 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.40 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. to 0.40 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000). The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0058] Example 9 A solution was prepared by adding 5.76 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.44 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. to 0.36 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000). The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0059] Example 10 3.20 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.16 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. were added to 3.20 g of a propylene glycol monomethyl ether solution containing 0.64 g of the polymer obtained in Synthesis Example 1 to form a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0060] Example 11 A solution was prepared by adding 3.30 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.18 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. to 3.08 g of a propylene glycol monomethyl ether solution containing 0.62 g of the polymer obtained in Synthesis Example 1. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0061] Example 12 A solution was prepared by adding 3.20 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.16 g of TG-G manufactured by Shikoku Chemical Industries, Ltd. to 3.20 g of a propylene glycol monomethyl ether solution containing 0.64 g of the polymer obtained in Synthesis Example 1. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0062] Example 13 Propylene glycol monomethyl ether solution 2 containing 0.44 g of the compound obtained in Synthesis Example 2 To 0.22 g of the above-mentioned solution, 3.99 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.36 g of Epotohto (registered trademark) YH-434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. were added to prepare a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0063] Example 14 A solution was prepared by adding 3.30 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.18 g of TG-G manufactured by Shikoku Chemicals Co., Ltd. to 3.08 g of a propylene glycol monomethyl ether solution containing 0.62 g of the compound obtained in Synthesis Example 2. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0064] Example 15 A solution was prepared by adding 3.76 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.30 g of TG-G manufactured by Shikoku Chemicals Co., Ltd. to 2.50 g of a propylene glycol monomethyl ether solution containing 0.50 g of the compound obtained in Synthesis Example 2. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0065] Example 16 A solution was prepared by adding 3.88 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.33 g of TG-G manufactured by Shikoku Chemicals Co., Ltd. to 2.35 g of a propylene glycol monomethyl ether solution containing 0.47 g of the compound obtained in Synthesis Example 2. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0066] Example 17 A solution was prepared by adding 3.98 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.36 g of TG-G manufactured by Shikoku Chemical Industries, Ltd. to 2.22 g of a propylene glycol monomethyl ether solution containing 0.44 g of the compound obtained in Synthesis Example 2. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0067] Example 18 A solution was prepared by adding 3.90 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, and 0.33 g of TG-G manufactured by Shikoku Chemicals Co., Ltd. to 2.33 g of a propylene glycol monomethyl ether solution containing 0.47 g of the compound obtained in Synthesis Example 3. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a protective film-forming composition.

[0068] <Comparative Example 1> To 0.60 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.18 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.02 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example was a polymer consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups. The crosslinking agent does not contain a crosslinking agent having two or more of at least one type of group selected from the group consisting of the following in one molecule.

[0069] <Comparative Example 2> To 0.49 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.29 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule of at least one type selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0070] <Comparative Example 3> To 0.60 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.18 g of 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol (manufactured by Honshu Chemical Industry Co., Ltd., trade name: TMOM-BP), and 0.02 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule of at least one type selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0071] <Comparative Example 4> To 0.49 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.29 g of 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol (manufactured by Honshu Chemical Industry Co., Ltd., trade name: TMOM-BP), and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule of at least one type selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0072] <Comparative Example 5> To 0.34 g of polyparahydroxystyrene (manufactured by Nippon Soda Co., Ltd., trade name: VP-8000), 11.52 g of propylene glycol monomethyl ether, 7.68 g of propylene glycol monomethyl ether acetate, 0.45 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule of at least one type selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0073] <Comparative Example 6> To 2.84 g of a propylene glycol monomethyl ether solution containing 0.57 g of the polymer obtained in Synthesis Example 1, 3.49 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, 0.22 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.02 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0074] <Comparative Example 7> To 2.81 g of a propylene glycol monomethyl ether solution containing 0.56 g of the compound obtained in Synthesis Example 2, 3.51 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, 0.22 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.02 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0075] <Comparative Example 8> To 2.20 g of a propylene glycol monomethyl ether solution containing 0.44 g of the compound obtained in Synthesis Example 2, 4.00 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, 0.35 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0076] <Comparative Example 9> To 2.03 g of a propylene glycol monomethyl ether solution containing 0.41 g of the compound obtained in Synthesis Example 3, 4.14 g of propylene glycol monomethyl ether, 13.44 g of propylene glycol monomethyl ether acetate, 0.38 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 0.01 g of pyridinium p-toluenesulfonate were added to form a solution. The solution was filtered through a polyethylene microfilter with a pore size of 0.02 μm to prepare a film-forming composition. The film-forming composition of this comparative example does not contain a crosslinker having two or more groups per molecule selected from the group consisting of glycidyl groups, terminal epoxy groups, epoxycyclopentyl groups, epoxycyclohexyl groups, oxetanyl groups, vinyl ether groups, isocyanate groups, and blocked isocyanate groups.

[0077] (Formation of a coating film on a silicon substrate) The protective film-forming compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 7 were applied to a silicon substrate. The film-forming composition prepared in Comparative Example 5 was applied by spin coating and baked at 220° C. for 60 seconds to form a coating film with a thickness of 100 nm.

[0078] (Formation of a coating on a titanium nitride film formed on a silicon substrate) The protective film-forming compositions prepared in Examples 8 to 18 and the film-forming compositions prepared in Comparative Examples 5 to 9 were spin-coated onto a 50 nm thick titanium nitride film formed on the surface of a silicon substrate, and baked at 260°C for 60 seconds to produce a coating film with a thickness of 100 nm.

[0079] (Photoresist solvent elution test) The protective film-forming compositions prepared in Examples 1 to 7 were used to prepare coating films on silicon substrates by baking at 220°C for 60 seconds, and the protective film-forming compositions prepared in Examples 8 to 18 were used to prepare coating films on titanium nitride films by baking at 260°C for 60 seconds. These coating films were then immersed for 1 minute in OK73 thinner (Tokyo Ohka Kogyo Co., Ltd., a mixture of propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate), a solvent used in applying photoresist. It was confirmed that the change in thickness of the coating film before and after immersion was 5% or less. This result indicates that the coating films prepared in Examples 1 to 18 can be laminated with a resist on top.

[0080] (Test for elution into resist developer) Coating films prepared on silicon substrates by baking at 220°C for 60 seconds using the protective film-forming compositions prepared in Examples 1 to 7, and coating films prepared on titanium nitride films by baking at 260°C for 60 seconds using the protective film-forming compositions prepared in Examples 8 to 18, were immersed for 1 minute in NMD-3 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), a developer used in photoresist development, and it was confirmed that the change in film thickness of the coating films before and after immersion was 5% or less.

[0081] (Testing the resistance of coatings on silicon substrates to basic hydrogen peroxide solutions) Coatings prepared using the protective film-forming compositions prepared in Examples 1 to 7 and the film-forming compositions prepared in Comparative Examples 1 to 5 were immersed in basic hydrogen peroxide aqueous solutions having the compositions shown in Table 1 below for the specified times (4 minutes, 8 minutes, and 12 minutes) at the temperatures shown in the table, and then rinsed with water and dried, after which the state of the coatings was visually inspected. The results are shown in Table 2 below. In Table 2, "□" indicates a state in which no peeling was observed in the coating film even after 4 minutes of treatment, "○" indicates a state in which no peeling was observed in the coating film even after 8 minutes of treatment, "◎" indicates a state in which no peeling was observed in the coating film even after 12 minutes of treatment, and "×" indicates a state in which peeling was observed in part or all of the coating film after 4 minutes of treatment. [Table 1] [Table 2]

[0082] The results in Table 2 above demonstrate that the coating films prepared using the protective film-forming compositions prepared in Examples 1 to 7 have sufficient resistance to basic hydrogen peroxide aqueous solutions. That is, it was found that these coating films can serve as protective films against basic hydrogen peroxide aqueous solutions. In particular, the coating films prepared using the protective film-forming compositions prepared in Examples 3 to 7 have excellent resistance to basic hydrogen peroxide aqueous solutions. On the other hand, it was shown that the coating films prepared using the film-forming compositions prepared in Comparative Examples 1 to 5 do not have resistance to basic hydrogen peroxide aqueous solutions, making it clear that these coating films cannot serve as protective films against basic hydrogen peroxide aqueous solutions.

[0083] (Testing the resistance of coatings on titanium nitride films to basic hydrogen peroxide solutions) Coatings prepared using the protective film-forming compositions prepared in Examples 8 to 18 and the film-forming compositions prepared in Comparative Examples 5 to 9 were immersed in basic hydrogen peroxide aqueous solutions having the compositions shown in Table 3 below for the specified times (1 minute, 1.5 minutes, and 2 minutes) at the temperatures shown in the table, and then rinsed with water. After drying, the state of the coatings was visually inspected. The results are shown in Table 4 below. In Table 4, "□" indicates that no peeling was observed in the coating film even after 1 minute of treatment, "○" indicates that no peeling was observed in the coating film even after 1.5 minutes of treatment, "◎" indicates that no peeling was observed in the coating film even after 2 minutes of treatment, and "×" indicates that peeling was observed in part or all of the coating film after 1 minute of treatment. [Table 3] [Table 4]

[0084] The results in Table 4 above demonstrate that the coating films prepared using the protective film-forming compositions prepared in Examples 8 to 18 have sufficient resistance to a basic hydrogen peroxide aqueous solution. In other words, it was found that these coating films can serve as protective films against a basic hydrogen peroxide aqueous solution. In particular, the coating films prepared using the protective film-forming compositions prepared in Examples 13 and 16 have excellent resistance to a basic hydrogen peroxide aqueous solution. On the other hand, it was shown that the coating films prepared using the film-forming compositions prepared in Comparative Examples 5 to 9 do not have resistance to a basic hydrogen peroxide aqueous solution, and these coating films cannot serve as protective films against a basic hydrogen peroxide aqueous solution. It became clear that this was not possible.

[0085] (Amount of blocking by a crosslinking agent of a substituent that reacts with the crosslinking agent in a compound having a weight-average molecular weight of 800 or more) In the coating films produced using the protective film-forming compositions prepared in Examples 1 to 18, the amount of crosslinker used to block substituents (hereinafter referred to as "substituents") that react with the crosslinker in compounds having a weight-average molecular weight of 800 or more was calculated based on the following formula (A) for crosslinkers with known chemical structures, and based on the following formula (B) for crosslinkers with unknown chemical structures. The results are shown in Table 5 below. Formula (A): 100 × (amount of crosslinking agent added to compound having a weight average molecular weight of 800 or more “mass%”) / [{100 / (molecular weight of one unit structure of a compound having a weight-average molecular weight of 800 or more) × (number of substituents of one unit structure of a compound having a weight-average molecular weight of 800 or more)} / (number of crosslinking points per molecule of crosslinking agent) × (molecular weight of crosslinking agent)] Formula (B): 100 × (amount of crosslinking agent added to compound having a weight average molecular weight of 800 or more “mass%”) / [{100 / (molecular weight of one unit structure of a compound having a weight-average molecular weight of 800 or more) × (number of substituents of one unit structure of a compound having a weight-average molecular weight of 800 or more)} × (molecular weight of the crosslinking agent per crosslinking point of the crosslinking agent)] [Table 5]

Claims

1. A pattern forming method comprising the steps of: forming a protective film on a semiconductor substrate, which may have an inorganic film formed on its surface, using a protective film-forming composition for a basic hydrogen peroxide aqueous solution; forming a resist pattern on the protective film; dry-etching the protective film using the resist pattern as a mask; and wet-etching the inorganic film or the semiconductor substrate using the protective film after dry etching as a mask, the method comprising the steps of: The protective film-forming composition includes a monomer having a group represented by the following formula (1) at its terminal and having a weight average molecular weight of 800 or more, a crosslinking agent, and an organic solvent: The pattern forming method, wherein the crosslinking agent has two or more groups in one molecule, each of which is at least one type of group selected from the group consisting of a glycidyl group, an epoxycyclopentyl group, an epoxycyclohexyl group, an oxetanyl group, a vinyl ether group, an isocyanate group, and a blocked isocyanate group. 【Chemistry 1】 (In the formula, X １ is represented by any one of the following formulas (3), (4), (5), (6), (7), (8), (9), (10), and (11), and R ０ represents a direct bond or an alkylene group having 1 or 2 carbon atoms; X ２ represents an alkyl group having 1 or 2 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a fluoro group, a represents an integer of 0 to 2, and b represents an integer of 1 to 3. １ is the following formula (3), b represents an integer of 2 or 3, and c represents an integer of 0 to 4. 【Chemistry 2】 (In the formula, R ２ represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms; R ３ represents a hydrogen atom or a linear, branched or cyclic hydrocarbon group having 1 to 8 carbon atoms, and e represents 0 or 1.

2. Above X １ The pattern forming method according to claim 1 , wherein is a group represented by formula (3), formula (4), formula (5), or formula (6).

3. The amount of the crosslinking agent added is determined by the amount of the substituent X that reacts with the crosslinking agent in the compound having a weight average molecular weight of 800 or more. １ When all of the substituents are taken as 100 mol %, the substituent X １ 2. The pattern forming method according to claim 1, wherein the amount is such that 20 mol % to 150 mol % of the compound is encapsulated.

4. 2. The pattern formation method according to claim 1, wherein the crosslinking agent has two or more glycidyl groups or epoxycyclohexyl groups in one molecule.

5. 2. The pattern formation method according to claim 1, wherein the blocked isocyanate group is a group represented by the following formula (12) or (13): 【Transformation 3】 (In the formula, R ４ and R ５ each independently represents an alkyl group having 1 to 5 carbon atoms; R ６ represents an alkyl group having 1 to 5 carbon atoms, d represents an integer of 1 to 3, and when d represents 2 or 3, R ６ The alkyl groups having 1 to 5 carbon atoms represented by the formula (I) may be different from each other.

6. The pattern forming method according to claim 1 , wherein the protective film-forming composition further comprises a crosslinking catalyst.

7. The pattern forming method according to claim 1 , wherein the protective film-forming composition further comprises a surfactant.

8. The pattern forming method according to claim 6 , wherein the protective film-forming composition further contains a surfactant.

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