Chemical-resistant protective film

Abstract

To provide a protective film-forming composition having excellent preservation stability and a favorable masking (protection) function against wet etching solutions when processing a semiconductor substrate, and a protective film manufactured using the composition.SOLUTION: A protective film-forming composition against wet etching solutions for semiconductors, comprises a polymer having a unit structure represented by Formula (1-1), a thermal polymerization initiator, and a solvent.SELECTED DRAWING: None

Description

[Technical Field]

[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 in semiconductor manufacturing. It also relates to 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. [Background technology]

[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, mainly using dry etching, although wet etching may be used depending on the type of substrate. Patent documents 1 and 2 disclose protective film-forming compositions for aqueous hydrogen peroxide solutions containing specific compounds. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2018 / 052130 [Patent Document 2] International Publication No. 2018 / 203464 [Overview of the project] [Problems that the invention aims to solve]

[0004] When a resist underlayer is used as an etching mask and the underlying substrate is processed by wet etching, the resist underlayer is required to have good masking function against the wet etching solution during substrate processing (i.e., the masked area can protect the substrate). In such cases, the resist underlayer is used as a protective film for the substrate. Conventionally, to achieve resistance to SC-1 (ammonia-hydrogen peroxide solution), a type of wet etching chemical, methods involving the application of low-molecular-weight compounds (e.g., gallic acid) as additives have been used, but this method has limitations in solving the aforementioned problems. The objective of this invention is to solve the above-mentioned problems. [Means for solving the problem]

[0005] This invention encompasses the following: [1] The following equation (1-1): [ka] (In formula (1-1), Ar represents a benzene ring, a naphthalene ring, or an anthracene ring, R 1 n1 represents a hydroxyl group, a mercapto group which may be protected by a methyl group, an amino group which may be protected by a methyl group, a halogeno group, or an alkyl group having 1 to 10 carbon atoms which may be substituted or interrupted by a heteroatom or substituted by a hydroxyl group, n1 represents an integer from 0 to 3, n2 represents 1 or 2, L 1 represents a single bond or an alkylene group with 1 to 10 carbon atoms, E represents an epoxy group, and T 1 When n2=1, it represents an alkylene group having 1 to 10 carbon atoms, which may be interrupted by a single bond, ether bond, ester bond, or amide bond. 1 A protective film-forming composition for semiconductor wet etching solutions, comprising a polymer having a unit structure represented by (where n2=2, it represents a nitrogen atom or an amide bond), a thermal polymerization initiator, and a solvent. [2] The above L 1 However, see equation (1-2) below: [ka] (In formula (1-2), R 2 , R 3independently represent a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, or a cyclobutyl group, and R 2 , R 3 (which may be bonded to each other to form a ring having 3 to 6 carbon atoms) and represents a protective film-forming composition for the wet etching solution for semiconductors described in [1]. [3] The protective film-forming composition for the wet etching solution for semiconductors according to [1], wherein the thermal polymerization initiator is a thermal cationic polymerization initiator. [4] The protective film-forming composition for the wet etching solution for semiconductors according to [3], wherein the thermal cationic polymerization initiator is an onium salt compound. [5] The protective film-forming composition for the wet etching solution for semiconductors according to any one of [1] to [4], wherein the semiconductor wet etching solution contains hydrogen peroxide solution. [6] A protective film for a wet etching solution for semiconductors, which is a fired product of a coating film composed of the protective film-forming composition according to any one of [1] to [5]. [7] A method for manufacturing a substrate with a resist pattern, which includes a step of applying and firing the protective film-forming composition according to any one of [1] to [5] on a semiconductor substrate to form a protective film as an underlayer film of a resist, forming a resist film on the protective film, and then performing exposure and development to form a resist pattern, and is characterized by being used in the manufacture of semiconductors. [8] A method for manufacturing a semiconductor device, which includes a step of forming a protective film on a semiconductor substrate, on which an inorganic film may be formed on the surface, using the protective film-forming composition according to any one of [1] to [5], forming a resist pattern on the protective film, dry-etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film or the semiconductor substrate, and wet-etching and / or cleaning the inorganic film or the semiconductor substrate using a wet etching solution for semiconductors with the protective film after dry-etching as a mask.

Advantages of the Invention

[0006] The protective film-forming composition of the present invention has a good masking function against wet etching solutions during the processing of the underlying substrate in the lithography process in semiconductor manufacturing, enabling easy microfabrication of semiconductor substrates.

Modes for Carrying Out the Invention

[0007] <Protective Film-Forming Composition> The protective film-forming composition of the present application has the following formula (1-1):

[0008]

Chemical

[0009] (In formula (1-1), Ar represents a benzene ring, a naphthalene ring, or an anthracene ring, and R 1 represents a hydroxy group, a mercapto group optionally protected with a methyl group, an amino group optionally protected with a methyl group, a halogeno group, or an alkyl group having 1 to 10 carbon atoms which may be substituted or interrupted with a hetero atom and may be substituted with a hydroxy group, as a substituent of a hydrogen atom contained in the benzene ring, naphthalene ring, or anthracene ring, n1 represents an integer of 0 to 3, n2 represents 1 or 2, L 1 represents a single bond or an alkylene group having 1 to 10 carbon atoms, E represents an epoxy group, T 1 represents a single bond or an alkylene group having 1 to 10 carbon atoms which may be interrupted with an ether bond, an ester bond, or an amide bond when n2 = 1, and T 1 represents a nitrogen atom or an amide bond when n2 = 2), and is a protective film-forming composition for a semiconductor wet etching solution containing a polymer having a unit structure represented by the formula, a thermal polymerization initiator, and a solvent.

[0010] The above R 1 may be an alkoxy group having 1 to 10 carbon atoms.

[0011] Examples of alkoxy groups with 1 to 10 carbon atoms include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, 1-methyl-n-butoxy, 2-methyl-n-butoxy, 3-methyl-n-butoxy, 1,1-dimethyl-n-propoxy, 1,2-dimethyl-n-propoxy, 2,2-dimethyl-n-propoxy, 1-ethyl-n-propoxy, n-hexyloxy, 1-methyl-n-pentyloxy, 2-methyl-n-pentyloxy, 3-methyl-n-pentyloxy, and 4-methyl-n-pentyloxy. Examples include ethyl-n-pentyloxy group, 1,1-dimethyl-n-butoxy group, 1,2-dimethyl-n-butoxy group, 1,3-dimethyl-n-butoxy group, 2,2-dimethyl-n-butoxy group, 2,3-dimethyl-n-butoxy group, 3,3-dimethyl-n-butoxy group, 1-ethyl-n-butoxy group, 2-ethyl-n-butoxy group, 1,1,2-trimethyl-n-propoxy group, 1,2,2-trimethyl-n-propoxy group, 1-ethyl-1-methyl-n-propoxy group, 1-ethyl-2-methyl-n-propoxy group, n-heptyloxy group, n-octyloxy group, and n-nonyloxy group.

[0012] The unit structure represented by formula (1-1) above may be one type or a combination of two or more types. For example, it may be a copolymer having multiple unit structures in which Ar is of the same type, and copolymers having multiple unit structures in which Ar is of different types, such as a unit structure in which Ar contains a benzene ring and a unit structure in which Ar contains a naphthalene ring, are not excluded from the scope of the present invention.

[0013] The phrase "may be interrupted" above means that, in the case of an alkylene group having 2 to 10 carbon atoms, any carbon-carbon bond in the alkylene group is interrupted by a heteroatom (i.e., an ether bond in the case of oxygen, a sulfide bond in the case of sulfur), an ester bond, or an amide bond; and in the case of a methylene group having 1 carbon atom, it means that one of the carbon atoms of the methylene group has a heteroatom (i.e., an ether bond in the case of oxygen, a sulfide bond in the case of sulfur), an ester bond, or an amide bond.

[0014] The above T 1 When n2=1, it represents an alkylene group having 1 to 10 carbon atoms, which may be interrupted by a single bond, an ether bond, an ester bond, or an amide bond. However, it is preferable that it is a combination of an ether bond and a methylene group (i.e., when "-T1-(E)n2" in formula (1-1) is a glycidyl ether group), an ester bond and a methylene group, or an amide bond and a methylene group.

[0015] A C1-C10 alkyl group that may be substituted with a heteroatom means that one or more hydrogen atoms of the above C1-C10 alkyl group are substituted with a heteroatom (preferably a halogen group).

[0016] The alkyl groups having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, and 1-ethyl-n-propyl group. Group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2 -dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,Examples include 3-trimethylcyclopropyl group, 1-ethyl-2-methylcyclopropyl group, 2-ethyl-1-methylcyclopropyl group, 2-ethyl-2-methylcyclopropyl group, 2-ethyl-3-methylcyclopropyl group, decyl group, methoxy group, ethoxy group, methoxymethyl group, ethoxymethyl group, methoxyethyl group, ethoxyethyl group, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, methylamino group, dimethylamino group, diethylamino group, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group, methylthio group, ethylthio group, mercaptomethyl group, 1-mercaptoethyl group, 2-mercaptoethyl group, etc.

[0017] The alkylene groups having 1 to 10 carbon atoms mentioned above include methylene group, ethylene group, n-propylene group, isopropylene group, cyclopropylene group, n-butylene group, isobutylene group, s-butylene group, t-butylene group, cyclobutylene group, 1-methyl-cyclopropylene group, 2-methyl-cyclopropylene group, n-pentylene group, 1-methyl-n-butylene group, 2-methyl-n-butylene group, 3-methyl-n-butylene group, 1,1-dimethyl-n-propylene group, 1,2-dimethyl-n-propylene group, 2,2-dimethyl-n-propylene, and 1-ethyl-n-propylene. Polyethylene group, cyclopentylene group, 1-methyl-cyclobutylene group, 2-methyl-cyclobutylene group, 3-methyl-cyclobutylene group, 1,2-dimethyl-cyclopropylene group, 2,3-dimethyl-cyclopropylene group, 1-ethyl-cyclopropylene group, 2-ethyl-cyclopropylene group, n-hexylene group, 1-methyl-n-pentylene group, 2-methyl-n-pentylene group, 3-methyl-n-pentylene group, 4-methyl-n-pentylene group, 1,1-dimethyl-n-butylene group, 1,2-dimethyl-n-butylene group, 1,3-dimethyl-n-butylene group , 2,2-dimethyl-n-butylene group, 2,3-dimethyl-n-butylene group, 3,3-dimethyl-n-butylene group, 1-ethyl-n-butylene group, 2-ethyl-n-butylene group, 1,1,2-trimethyl-n-propylene group, 1,2,2-trimethyl-n-propylene group, 1-ethyl-1-methyl-n-propylene group, 1-ethyl-2-methyl-n-propylene group, cyclohexylene group, 1-methyl-cyclopentylene group, 2-methyl-cyclopentylene group, 3-methyl-cyclopentylene group, 1-ethyl-cyclobutylene group, 2-ethyl-cyclobutylene n group, 3-ethyl-cyclobutylene group, 1,2-dimethyl-cyclobutylene group, 1,3-dimethyl-cyclobutylene group, 2,2-dimethyl-cyclobutylene group, 2,3-dimethyl-cyclobutylene group, 2,4-dimethyl-cyclobutylene group, 3,3-dimethyl-cyclobutylene group, 1-n-propyl-cyclopropylene group, 2-n-propyl-cyclopropylene group, 1-isopropyl-cyclopropylene group, 2-isopropyl-cyclopropylene group, 1,2,2-trimethyl-cyclopropylene group, 1,2,3-trimethyl-cyclopropylene group, 2,2,Examples include 3-trimethylcyclopropylene group, 1-ethyl-2-methylcyclopropylene group, 2-ethyl-1-methylcyclopropylene group, 2-ethyl-2-methylcyclopropylene group, 2-ethyl-3-methylcyclopropylene group, n-heptylene group, n-octylene group, n-nonylene group, or n-decanylene group.

[0018] The above L 1 represents a single bond or an alkylene group with 1 to 10 carbon atoms, as shown in formula (1-2):

[0019] [ka]

[0020] (In formula (1-2), R 2 , R 3 R independently represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, and a cyclobutyl group. 2 , R 3 It is preferable that these be represented as R (which may be bonded to each other to form a ring with 3 to 6 carbon atoms). 2 , R 3 Both are hydrogen atoms (that is, CR) 2 R 3 It is preferable that the group is a methylene group.

[0021] The above-mentioned halogen group refers to a halogen-X(F,Cl,Br,I) substituted with hydrogen.

[0022] The polymer described above is not particularly limited as long as it satisfies the unit structure of formula (1) above. It may be manufactured by a method known to the public. Commercial products may also be used. Examples of commercial products include the heat-resistant epoxy novolac resin EOCN® series (manufactured by Nippon Kayaku Co., Ltd.) and the epoxy novolac resin DEN® series (manufactured by Dow Chemical Japan Ltd.).

[0023] The weight-average molecular weight of the above polymers is 100 or more, 500-200,000, 600-50,000, and 700-10,000.

[0024] Examples of polymers of this application include those having the following unit structures.

[0025] [ka]

[0026] <Thermal polymerization initiator> The thermal polymerization initiators of this application differ from so-called photopolymerization initiators in that they are compounds in which acid is predominantly generated by heating (e.g., 50°C to 300°C) compared to when irradiated with light. The thermal polymerization initiators of this application are preferably thermal cationic polymerization initiators. Specific examples include sulfonic acid compounds such as pyridinium p-toluenesulfonate, pyridinium p-hydroxybenzenesulfonate, pyridinium trifluoromethanesulfonate, p-toluenesulfonic acid, p-hydroxybenzenesulfonic acid, trifluoromethanesulfonic acid, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, chlorobenzenesulfonic acid, methyl 4-phenolsulfonate, benzenesulfonic acid, naphthalenesulfonic acid, citric acid, benzoic acid, and other carboxylic acid compounds, as well as trifluoromethanesulfonic acid. Examples include the ammonium salts K-PURE® TAG2689, TAG2690, TAG2678, CXC-1614, etc. (all manufactured by King Industries), 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, the aromatic sulfonium salts Sun-Aid® SI series (e.g., SI-45, SI-60, SI-80, SI-100, SI-110, SI-150, etc.) (manufactured by Sanshin Chemical Industry Co., Ltd.), and other alkyl organic sulfonates.

[0027] Among these, it is preferable that the onium salt compound is preferred, preferred that the quaternary ammonium salt-containing compound is preferred, and preferred that the quaternary ammonium salt of trifluoromethanesulfonic acid is preferred. These thermal polymerization initiators may be included individually or in combination of two or more.

[0028] The content of the above-mentioned thermal acid generator in the protective film-forming composition is 0.0001 to 20% by weight, preferably 0.01 to 15% by weight, and more preferably 0.1 to 10% by weight, based on the total solid content of the protective film-forming composition.

[0029] <Solvent> The protective film-forming composition of the present invention can be prepared by dissolving each of the above components in a solvent, preferably an organic solvent, and is used in a homogeneous solution state.

[0030] The solvent used in the protective film-forming composition according to the present invention is not particularly limited, as long as it is a solvent capable of dissolving the solid components contained in the protective film-forming composition according to the present invention at room temperature. In particular, since the protective film-forming composition according to the present invention is used in a uniform solution state, it is recommended to use a solvent commonly used in lithography processes in combination, considering its coating performance.

[0031] Examples of the aforementioned organic solvents 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 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, and cyclohexanoyl ether. Examples of solvents include 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 individually or in combination of two or more.

[0032] 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.

[0033] <Crosslinking agent> The protective film-forming composition of the present invention may contain a crosslinking agent component. Examples of such crosslinking agents include melamine-based, substituted urea-based, or polymer-based versions thereof. Preferably, the crosslinking agent has at least two crosslinking substituents and is a compound such as methoxymethylated glycoluryl, butoxymethylated glycoluryl, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, methoxymethylated thiourea, or methoxymethylated thiourea. Condensed forms of these compounds can also be used.

[0034] Furthermore, a highly heat-resistant crosslinking agent can be used as the crosslinking agent. As a highly heat-resistant crosslinking agent, a compound containing a crosslinking substituent having an aromatic ring (e.g., a benzene ring, a naphthalene ring) in its molecule can be used.

[0035] Examples of this compound include compounds having the substructure of formula (2-1) below, or polymers or oligomers having the repeating unit of formula (2-2) below.

[0036] [ka]

[0037] The above R 18 , R 19 , R 20 , and R 21 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl groups described above can be used.

[0038] n3 is 1 ≤ n3 ≤ 6 - n4, n4 is 1 ≤ n4 ≤ 5, n5 is 1 ≤ n5 ≤ 4 - n6, and n6 is 1 ≤ n6 ≤ 3.

[0039] Compounds represented by formula (2-1) are exemplified by formulas (2-3) to (2-19) below.

[0040] [ka]

[0041] 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 (2-15) can be obtained from Asahi Organic Chemicals Co., Ltd. under the trade name TMOM-BP.

[0042] The amount of crosslinking agent added varies depending on the coating solvent used, the substrate used, the required solution viscosity, and the required film shape, but is 0.001 to 80% by weight, preferably 0.01 to 50% by weight, and more preferably 0.1 to 40% by weight, relative to the total solid content of the protective film-forming composition. These crosslinking agents may undergo crosslinking reactions by self-condensation, but if crosslinkable substituents are present in the polymer of the present invention, they can undergo crosslinking reactions with those crosslinkable substituents.

[0043] <Surfactants> The protective film-forming composition of the present invention may optionally contain a surfactant to improve its coatability on semiconductor substrates. Examples of such 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 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 mono Examples include nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters like stearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorine-based surfactants such as F-Top® EF301, EF303, and EF352 (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.); Megafac® F171, F173, R-30, R-40, and R-40-LM (manufactured by DIC Corporation); Florard FC430 and FC431 (manufactured by Sumitomo 3M Limited); Asahi Guard® AG710; Surflon® 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 individually or in combination of two or more. If the protective film-forming composition contains a surfactant, its content is 0.0001 to 10% by weight, preferably 0.01 to 5% by weight, relative to the total solid content of the protective film-forming composition.

[0044] <Protective film forming composition> The solid content of the protective film-forming composition according to the present invention is usually 0.1 to 70% by mass, preferably 0.1 to 60% by mass. The solid content is the percentage of all components in the protective film-forming composition excluding the solvent. The percentage of polymer in the solid content is preferably in the following order: 1 to 100% by mass, 1 to 99.9% by mass, 50 to 99.9% by mass, 50 to 95% by mass, and 50 to 90% by mass.

[0045] <Wet etching solution for semiconductors> 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.

[0046] For semiconductor wet etching solutions, general chemicals used for etching semiconductor wafers can be used, including substances that exhibit both acidic and basic properties.

[0047] 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.

[0048] 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, other substances that can make the pH basic, such as a solution obtained by mixing urea with hydrogen peroxide and generating ammonia by thermal decomposition of urea through heating, which ultimately makes the pH basic, can also be used as a chemical solution for wet etching.

[0049] These chemical solutions may contain additives such as surfactants.

[0050] 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.

[0051] <Method for manufacturing protective films for semiconductor wet etching solutions, substrates with resist patterns, and semiconductor devices> The following describes a method for manufacturing a substrate with a resist pattern and a method for manufacturing a semiconductor device using the protective film forming composition according to the present invention.

[0052] A resist patterned substrate according to the present invention can be manufactured by applying the above-described protective film forming composition onto a semiconductor substrate and firing it.

[0053] 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.

[0054] 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-PhosphoSilicate Glass) films, titanium nitride films, titanium oxynitride films, tungsten nitride films, gallium nitride films, and gallium arsenide films.

[0055] 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, 0.002 μm to 1 μm, 0.005 μm to 0.5 μm (= 5 nm to 500 nm), 10 nm to 300 nm, 15 nm to 200 nm, and 30 nm to 150 nm. If the baking temperature is lower than the above range, crosslinking may be insufficient, and the resulting protective film may not be able to obtain sufficient resistance to the resist solvent or wet etching solution. On the other hand, if the baking temperature is higher than the above range, the protective film may decompose due to the heat.

[0056] The resist pattern is formed by passing it through a mask (reticle) to form a predetermined pattern. For example, exposure with i-line, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet) light, or EB (electron beam) lithography is used. For development, an alkaline developer is used, with a development temperature of 5°C to 50°C and a development time of 10 to 300 seconds, which can be appropriately selected. As the alkaline developer, aqueous solutions of alkalis such as inorganic alkalis like sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, primary amines like ethylamine and n-propylamine, secondary amines like diethylamine and di-n-butylamine, tertiary amines like triethylamine and methyldiethylamine, alcohol amines like dimethylethanolamine and triethanolamine, quaternary ammonium salts like tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, and cyclic amines like pyrrole and piperidine can be used. Furthermore, an appropriate amount of alcohol such as isopropyl alcohol or a nonionic surfactant can be added to the aqueous solution of the above alkalis. Among these, preferred developers are quaternary ammonium salts, more preferably tetramethylammonium hydroxide and choline. Furthermore, surfactants and other additives can be added to these developers. Alternatively, instead of an alkaline developer, development can be performed using an organic solvent such as butyl acetate, developing the portions of the photoresist where the alkaline dissolution rate has not improved.

[0057] 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. [Examples]

[0058] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0059] The apparatus used to measure the weight-average molecular weight of the compounds used in the following examples is shown. Equipment: HLC-8320GPC manufactured by Tosoh Corporation GPC columns: Shodex® and Asahipak® (Showa Denko K.K.) Column temperature: 40℃ Solvent: Tetrahydrofuran (THF) Flow rate: 0.6mL / min Standard sample: Polystyrene (Tosoh Corporation)

[0060] Meaning of symbols; PGME: Propylene glycol monomethyl ether PGMEA: Propylene glycol monomethyl ether acetate

[0061] <Example 1> 2.00 g of epoxy novolac resin EOCN-104S (a product of Nippon Kayaku Co., Ltd., corresponding to formula (1)) (50% by mass PGMEA solution, weight-average molecular weight 3100) was mixed with 2.08 g of K-PURE [trademark registered] TAG-2689 (a product of King Industries Co., Ltd.) (0.5% by mass PGME solution) as a thermoacid generator, and further mixed with 19.23 g of PGMEA and 6.62 g of PGME as solvents to make a 3.5% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a protective film-forming composition.

[0062] [ka]

[0063] <Example 2> 2.08 g of epoxy novolac resin DEN438 (a product of Dow Chemical Japan Ltd., corresponding to formula (2)) (50% by mass PGME solution, weight-average molecular weight 900) was mixed with 2.08 g of K-PURE [trademark registered] TAG-2689 (a product of King Industries) (0.5% by mass PGME solution) as a thermal acid generator, and further mixed with 20.27 g of PGMEA and 5.58 g of PGME as solvents to make a 3.5% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a protective film-forming composition.

[0064] [ka]

[0065] <Comparative Example 1> 10.40 g of Epolid GT401 (a product of Daicel Corporation, corresponding to formula (3), with a weight-average molecular weight of 700) (10% by mass PGMEA solution) was mixed with 2.08 g of K-PURE [trademark registered] TAG-2689 (a product of King Industries) (0.5% by mass PGME solution) as a thermal acid generator, and further mixed with 10.91 g of PGMEA and 6.62 g of PGME as solvents to make a 3.5% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a protective film-forming composition.

[0066] [ka]

[0067] <Comparative Example 2> 2.00 g of epoxy novolac resin EOCN-104S (a product of Nippon Kayaku Co., Ltd., corresponding to formula (1)) (50% by mass PGMEA solution, weight-average molecular weight 3100) was mixed with 0.05 g of triphenylsulfonium trifluoromethanesulfonate (manufactured by Midori Chemical Co., Ltd., trade name TPS105) as a photoacid generator, and further mixed with 19.27 g of PGMEA and 8.69 g of PGME as solvents to make a 3.5% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a protective film-forming composition.

[0068] <Comparative Example 3> 10.00 g of Epolid GT401 (a product of Daicel Corporation, corresponding to formula (3), with a weight-average molecular weight of 700) (10% by mass PGMEA solution) was mixed with 0.05 g of triphenylsulfonium trifluoromethanesulfonate (manufactured by Midori Chemical Co., Ltd., trade name TPS105) as a photoacid generator, and further mixed with 11.27 g of PGMEA and 8.69 g of PGME as solvents to make a 3.5% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a protective film-forming composition.

[0069] [Thermosetting Test] The protective film-forming compositions prepared in Examples 1 and 2, and Comparative Examples 1 to 3, were each coated onto silicon wafers using a spinner. The resulting coatings were then baked on a hot plate at 250°C for 1 minute to form protective films (thickness 90 nm). These protective films were immersed for 1 minute in OK73 thinner (manufactured by Tokyo Ohka Kogyo Co., Ltd., PGME / PGMEA=7 / 3 mixed solvent), a solvent used in photoresist solutions, to evaluate their resistance to the solvent. ○ indicated insoluble, and × indicated dissolved. The results are shown in Table 1.

[0070] [Photocuring Test] The protective film-forming compositions prepared in Examples 1 and 2, and Comparative Examples 1 to 3, were each coated onto silicon wafers using a spinner. The resulting coated films were then baked on a hot plate at 100°C for 1 minute to form protective films (thickness 90 nm). These protective films were then subjected to 172 nm light irradiation at approximately 500 mJ / cm² in a nitrogen atmosphere using a SUS867 172 nm light irradiation device manufactured by Ushio Inc. 2 The wafer was irradiated across its entire surface. Furthermore, it was immersed for 1 minute in OK73 thinner (manufactured by Tokyo Ohka Kogyo Co., Ltd., a PGME / PGMEA=7 / 3 mixed solvent), a solvent used in photoresist solutions, to evaluate its resistance to the solvent. ○ indicated insoluble material, and × indicated dissolved material. The results are shown in Table 1.

[0071] [Testing of optical parameters] The protective film-forming compositions prepared in Examples 1 and 2 and Comparative Example 1 were applied to a silicon substrate using a spinner. The resulting coating was then baked on a hot plate at 250°C for 1 minute to form a protective film (thickness 90 nm). Furthermore, the protective film-forming compositions prepared in Comparative Examples 2 and 3 were applied to a silicon substrate using a spinner. The resulting coating was then baked on a hot plate at 100°C for 1 minute, and 172 nm light at approximately 500 mJ / cm² was irradiated in a nitrogen atmosphere using a SUS867 172 nm light irradiation device. 2 The entire wafer was irradiated to form a protective film (thickness 90 nm).

[0072] Next, the refractive index (n-value) and attenuation coefficient (k-value) of these protective films were measured at wavelengths of 193 nm and 248 nm using a spectroscopic ellipsometer (JAWoollam, VUV-VASE VU-302). The results are shown in Table 1.

[0073] [Basic hydrogen peroxide solution resistance test] The protective film-forming compositions prepared in Examples 1 and 2, and Comparative Examples 1 to 3, were evaluated for APM resistance immediately after preparation and after the solutions were stored at 35°C for one week.

[0074] The protective film-forming compositions prepared in Examples 1 and 2 and Comparative Example 1 were applied to a silicon substrate on which a titanium nitride film had been formed on its surface using a spinner. The resulting coated film was then baked on a hot plate at a temperature of 250°C for 1 minute to form a protective film (thickness 90 nm). Furthermore, the protective film-forming compositions prepared in Comparative Examples 2 and 3 were applied to silicon substrates on which titanium nitride films had been formed on the surface using a spinner. The resulting coated films were then baked on a hot plate at 100°C for 1 minute, and 172nm light at a wavelength of approximately 500 mJ / cm² was applied in a nitrogen atmosphere using a SUS867 172nm light irradiation device. 2 The entire wafer was irradiated to form a protective film (thickness 90 nm).

[0075] The protective film created on the silicon substrate was then immersed in a basic hydrogen peroxide aqueous solution (abbreviated as APM in Table 1) with the composition shown in Table 2 below, at the temperature shown in the same table. The time it took for the protective film to peel off the silicon substrate was measured to evaluate its APM resistance. The results are shown in Table 1. In Table 1, "○" indicates that no peeling of the resist underlayer film was observed after 10 minutes of immersion, and "×" indicates that peeling was observed in part or all of the resist underlayer film after 10 minutes of immersion.

[0076] [Table 1]

[0077] [Table 2]

[0078] As shown in Table 1 above, the protective films prepared using the protective film-forming compositions in Examples 1 and 2 and Comparative Example 1 showed solvent resistance to the resist solvent only through thermal curing. On the other hand, the protective films prepared using the protective film-forming compositions in Comparative Examples 2 and 3 showed solvent resistance to the resist solvent only through photocuring. Furthermore, as shown in Table 1, the resin used in the protective film-forming composition of the present invention showed superior APM resistance compared to the protective film-forming compositions prepared in Comparative Examples 2 and 3.

[0079] Furthermore, the resin used in the protective film-forming composition of the present invention showed superior storage stability compared to the protective film-forming composition prepared in Comparative Example 1. This suggests that the protective film-forming composition prepared in Comparative Example 1 had poor storage stability, resulting in insufficient crosslinking and thus no APM resistance. [Industrial applicability]

[0080] The protective film-forming composition according to the present invention provides a protective film with excellent resistance when a wet etching solution is applied to a substrate during processing.

Claims

1. The following: 【Chemistry 1】 A protective film-forming composition for semiconductor wet etching solutions, comprising a polymer consisting only of unit structures selected from, a thermal polymerization initiator, and a solvent.

2. The protective film-forming composition for semiconductor wet etching solutions according to Claim 1, wherein the thermal polymerization initiator is a thermal cationic polymerization initiator.

3. The protective film-forming composition for semiconductor wet etching solutions according to claim 2, wherein the thermal cationic polymerization initiator is an onium salt compound.

4. A protective film-forming composition for a semiconductor wet etching solution according to any one of claims 1 to 3, wherein the semiconductor wet etching solution comprises hydrogen peroxide.

5. A protective film for semiconductor wet etching solutions, characterized in that it is a fired product of a coating film made from the protective film forming composition described in any one of Claims 1 to 4.

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