Resist underlayer film forming composition

Abstract

Provided is a composition for forming a resist underlayer film, the composition exhibiting strong etching resistance, having a good dry etching rate ratio and a good optical constant, and being capable of forming a film that provides good coverage over a so-called multilevel substrate and that is flat with reduced difference in thickness after embedding. Also provided are: a resist underlayer film that uses said composition for forming a resist underlayer film; and a method for producing a semiconductor device. The composition for forming a resist underlayer film contains: a polymer having the partial structure represented by formula (1); and a solvent. (In the formula, Ar represents an optionally substituted C6-20 aromatic group.)

Description

[Technical field]

[0001] The present invention relates to a resist underlayer film-forming composition that exhibits high etching resistance, a good dry etching rate ratio and optical constants, has good coverage even for so-called stepped substrates, has a small film thickness difference after embedding, and is capable of forming a flat film; a resist underlayer film using the resist underlayer film-forming composition; and a method for producing a semiconductor device. [Background technology]

[0002] In recent years, resist underlayer film materials for multilayer resist processes are required to function as anti-reflective films, particularly against short-wavelength exposure, to have appropriate optical constants, and to also have etching resistance in substrate processing. For this reason, the use of polymers having a repeating unit containing a benzene ring has been proposed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2004-354554 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to reduce the thickness of the resist layer required for the finer resist pattern, a lithography process is known in which at least two layers of resist underlayer film are formed and the resist underlayer film is used as a mask material. This is a method in which at least one organic film (lower organic film) and at least one inorganic underlayer film are provided on a semiconductor substrate, the inorganic underlayer film is patterned using the resist pattern formed on the upper resist film as a mask, and the lower organic film is patterned using the pattern as a mask, and it is said that a pattern with a high aspect ratio can be formed. Examples of materials for forming the at least two layers include a combination of an organic resin (e.g., acrylic resin, novolac resin) and an inorganic material (silicon resin (e.g., organopolysiloxane), inorganic silicon compound (e.g., SiON, SiO2), etc.). Furthermore, in recent years, a double patterning technique in which two lithography processes and two etching processes are performed to obtain one pattern has been widely applied, and the above multilayer process is used in each process. In this case, the organic film that is deposited after the initial pattern is formed is required to have the property of flattening steps.

[0005] However, there is a problem that the coating ability of the composition for forming a resist underlayer film is low for so-called stepped substrates in which the resist pattern formed on the substrate to be processed has differences in height and density, resulting in large differences in film thickness after filling, making it difficult to form a flat film.

[0006] The present invention has been made based on the solution of such problems, and aims to provide a resist underlayer film-forming composition that exhibits high etching resistance, a good dry etching rate ratio and optical constants, has good coverage even for so-called stepped substrates, has a small film thickness difference after filling, and is capable of forming a flat film. Another object of the present invention is to provide a resist underlayer film and a method for manufacturing a semiconductor device using the resist underlayer film-forming composition. [Means for solving the problem]

[0007] The present invention encompasses the following: [1] A resist underlayer film forming composition comprising a polymer having a partial structure represented by the following formula (1) and a solvent: [ka] (In the formula, Ar represents an aromatic group having 6 to 20 carbon atoms which may be substituted.) [2] The resist underlayer film forming composition according to [1], wherein Ar in the formula (1) is a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof. [3] The resist underlayer film forming composition according to [1], wherein Ar in the formula (1) is a naphthyl group, an anthracenyl group, or a combination thereof. [4] The resist underlayer film forming composition according to any one of [1] to [3], further comprising a crosslinking agent. [5] The resist underlayer film forming composition according to any one of [1] to [4], further comprising an acid and / or an acid generator. [6] The resist underlayer film forming composition according to [1], wherein the boiling point of the solvent is 160° C. or higher. [7] A resist underlayer film, which is a fired product of a coating film comprising the resist underlayer film forming composition according to any one of [1] to [6]. [8] forming a resist underlayer film on a semiconductor substrate using the resist underlayer film forming composition according to any one of [1] to [6]; forming a resist film on the formed resist underlayer film; A step of forming a resist pattern by irradiating the formed resist film with light or an electron beam and developing it; A step of etching and patterning the resist underlayer film through the formed resist pattern; and A process for processing a semiconductor substrate through a patterned resist underlayer film. A method for manufacturing a semiconductor device comprising the steps of: Effect of the Invention

[0008] The resist underlayer film forming composition of the present invention not only has high etching resistance, and a good dry etching rate ratio and optical constants, but also the resist underlayer film obtained has good coverage even for so-called stepped substrates, has a small film thickness difference after filling, forms a flat film, and achieves finer substrate processing. In particular, the resist underlayer film forming composition of the present invention is effective for a lithography process in which at least two resist underlayer films are formed for the purpose of reducing the resist film thickness, and the resist underlayer film is used as an etching mask. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Resist underlayer film forming composition] The resist underlayer film forming composition according to the present invention comprises a polymer having a partial structure represented by the following formula (1): [ka] (In the formula, Ar represents an aromatic group having 6 to 20 carbon atoms which may be substituted.) It contains a solvent and other ingredients. They will be explained in order below.

[0010] [Polymer having a partial structure represented by formula (1)]

[0011] In the partial structure represented by formula (1), Ar represents an aromatic group having 6 to 20 carbon atoms which may be substituted. Examples of the aromatic group having 6 to 20 carbon atoms include groups in which one hydrogen atom has been removed from an aromatic compound which may be substituted. Such aromatic compounds are (a) may be a monocyclic compound such as benzene; (b) may be a fused ring compound such as naphthalene; (c) may be a heterocyclic compound such as furan, thiophene, or pyridine; (d) A compound in which the aromatic rings of (a) to (c) are bonded together by a single bond, such as biphenyl. (e) -(CH2), such as phenylnaphthylaminen The compound may be one in which two or more aromatic rings selected from (a) to (d) are linked by one or more spacers exemplified by -(n=1 to 20), -CH=CH-, -C≡C-, -N=N-, -NH-, -NR-, -NHCO-, -NRCO-, -S-, -COO-, -O-, -CO- and -CH=N-. Two or more of these spacers may be linked.

[0012] Specific examples of aromatic compounds include benzene, toluene, xylene, mesitylene, cumene, styrene, indene, naphthalene, azulene, anthracene, phenanthrene, naphthacene, triphenylene, pyrene, chrysene, thiophene, furan, pyridine, pyrimidine, pyrazine, pyrrole, oxazole, thiazole, imidazole, naphthalene, anthracene, quinoline, carbazole, quinazoline, purine, indolizine, benzothiophene, benzofuran, indole, phenylindole, and acridine.

[0013] The aromatic group may be singly or multiply substituted with at least one group selected from the group consisting of a halogen atom, an alkyl group having 1 to 20 carbon atoms, a condensed ring group, a heterocyclic group, a hydroxy group, an amino group, a nitro group, an ether group, an alkoxy group, a cyano group, and a carboxyl group.

[0014] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0015] Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups which may or may not have a substituent, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, a cyclohexyl group, a 2-ethylhexyl group, an n-nonyl group, an isononyl group, a p-tert-butylcyclohexyl group, an n-decyl group, an n-dodecylnonyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl group. Examples of the cyclic alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like, which may or may not have a substituent.

[0016] Preferably, it is an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and further preferably an alkyl group having 1 to 4 carbon atoms.

[0017] Examples of the alkyl group having 1 to 20 carbon atoms interrupted by an oxygen atom, a sulfur atom or an amide bond include those containing the structural unit -CH2-O-, -CH2-S-, -CH2-NHCO- or -CH2-CONH-. -O-, -S-, -NHCO- or -CONH- may be one unit or two or more units in the alkyl group. Specific examples of the alkyl group having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO- or -CONH- units include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylcarbonylamino group, a propylcarbonylamino group, a butylcarbonylamino group, a methylaminocarbonyl group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl ... and the like, and further, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, or octadecyl groups, each of which is substituted with a methoxy, ethoxy, propoxy, butoxy, methylthio, ethylthio, propylthio, butylthio, methylcarbonylamino, ethylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, or the like. Preferred are methoxy, ethoxy, methylthio, and ethylthio groups, and more preferred are methoxy and ethoxy groups.

[0018] The fused ring group is a substituent derived from a fused ring compound. Specific examples of the fused ring group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a naphthacenyl group, a triphenylenyl group, a pyrenyl group, and a chrysenyl group. Of these, a phenyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group are preferred.

[0019] The heterocyclic group is a substituent derived from a heterocyclic compound, and specific examples thereof include a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrazine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, a quinoline group, a carbazole group, a quinazoline group, a purine group, an indolizine group, a benzothiophene group, a benzofuran group, an indole group, an acridine group, an isoindole group, a benzimidazole group, an isoquinoline group, a quinoxaline group, a cinnoline group, a pteridine group, a chromene group (benzopyran group), an isochromene group (benzopyran group), a xanthene group, Examples of such groups include a thiazole group, a pyrazole group, an imidazoline group, and an azine group. Among these, a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrazine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, a quinoline group, a carbazole group, a quinazoline group, a purine group, an indolizine group, a benzothiophene group, a benzofuran group, an indole group, and an acridine group are preferred, and a thiophene group, a furan group, a pyridine group, a pyrimidine group, a pyrrole group, an oxazole group, a thiazole group, an imidazole group, and a carbazole group are most preferred.

[0020] Preferably, Ar is a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group, more preferably a naphthyl group or an anthracenyl group.

[0021] When the polymer having the partial structure represented by formula (1) has a plurality of Ar in its molecule, they may be the same or different from each other.

[0022] A polymer having a partial structure represented by formula (1) may contain a partial structure other than the partial structure in an amount that does not impair the effects of the present invention (for example, less than 50 mol%, less than 30 mol%, less than 20 mol%, less than 10 mol%, or less than 5 mol%). The mass ratio of the Ar group to the entire polymer is usually 1:0.1 to 1:0.5, and preferably 1:0.15 to 1:0.4.

[0023] The weight average molecular weight Mw of the polymer having the partial structure represented by formula (1) is usually 4,400 or less, preferably 2,200 or less, more preferably 1,100 or less, and is usually 500 or more.

[0024] [Synthesis method] A polymer having a partial structure represented by formula (1) can be obtained by reacting a main chain polymer having at least one epoxy group in the molecule with an aromatic carboxylic acid under appropriate conditions.

[0025] Examples of main chain polymers having at least one epoxy group in the molecule include [ka] [ka] [ka] For example, a product name NC-7300L (manufactured by Nippon Kayaku Co., Ltd.) is available. Incidentally, an aromatic unit not having a glycidyl group may be included as long as the effect of the present invention is not impaired.

[0026] Examples of the aromatic carboxylic acid include benzoic acid, 1-naphthalenecarboxylic acid, 9-anthracenecarboxylic acid, and 1-pyrenecarboxylic acid.

[0027] The reaction may be carried out in a suitable solvent and in the presence of a suitable catalyst. Such a solvent is not particularly limited as long as it can uniformly dissolve the main chain polymer having at least one epoxy group in the molecule and the aromatic carboxylic acid and does not inhibit the reaction or induce side reactions.

[0028] For example, 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, cyclohexanone, cyclohexanone, Examples of the solvent include butanone, 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. Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, and cyclohexanone are preferred.

[0029] Examples of the catalyst include quaternary ammonium salts such as tetrabutylammonium bromide, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide, and phosphine compounds such as triphenylphosphine. Ethyltriphenylphosphonium bromide is preferred.

[0030] The reaction temperature is usually 40° C. to 200° C. The reaction time is selected variously depending on the reaction temperature, but is usually about 30 minutes to 50 hours.

[0031] In order to prevent unreacted acid, catalyst, inactivated catalyst, etc. from remaining in the reaction system, a cation exchange resin or anion exchange resin for catalysts can be used.

[0032] [solvent] The solvent for the resist underlayer film-forming composition according to the present invention can be any solvent that can dissolve the above-mentioned reaction product without any particular limitation. In particular, since the resist underlayer film-forming composition according to the present invention is used in the form of a homogeneous solution, it is recommended to use a solvent that is generally used in lithography processes in combination with the composition, taking into account its coating performance.

[0033] Examples of such solvents include methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl isobutyl carbinol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoether ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl acetate, ethyl acetate, amyl acetate, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate,Butyl butyrate, isobutyl butyrate, ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methoxypropyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl Examples of the solvent include 3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, 4-methyl-2-pentanol, and γ-butyrolactone. These solvents can be used alone or in combination of two or more.

[0034] In addition, the following compounds described in WO2018 / 131562A1 can also be used. [ka] (R in formula (i) 1 , R 2 and R 3 each represents a hydrogen atom, an oxygen atom, a sulfur atom, or an alkyl group having 1 to 20 carbon atoms which may be interrupted by an amide bond, and may be the same or different and may be bonded to each other to form a ring structure.

[0035] Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups which may or may not have a substituent, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, a cyclohexyl group, a 2-ethylhexyl group, an n-nonyl group, an isononyl group, a p-tert-butylcyclohexyl group, an n-decyl group, an n-dodecylnonyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl group. Preferably, it is an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and further preferably an alkyl group having 1 to 4 carbon atoms.

[0036] Examples of the alkyl group having 1 to 20 carbon atoms interrupted by an oxygen atom, a sulfur atom or an amide bond include those containing the structural unit -CH2-O-, -CH2-S-, -CH2-NHCO- or -CH2-CONH-. -O-, -S-, -NHCO- or -CONH- may be one unit or two or more units in the alkyl group. Specific examples of the alkyl group having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO- or -CONH- units include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylcarbonylamino group, a propylcarbonylamino group, a butylcarbonylamino group, a methylaminocarbonyl group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl ... and the like, and further, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, or octadecyl groups, each of which is substituted with a methoxy, ethoxy, propoxy, butoxy, methylthio, ethylthio, propylthio, butylthio, methylcarbonylamino, ethylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, or the like. Preferred are methoxy, ethoxy, methylthio, and ethylthio groups, and more preferred are methoxy and ethoxy groups.

[0037] Since these solvents have a relatively high boiling point, they are also effective in imparting high embedding properties and high planarization properties to the resist underlayer film-forming composition.

[0038] Specific examples of preferred compounds represented by formula (i) are given below. [ka]

[0039] Among the above, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and The formula: [ka] Particularly preferred compounds represented by formula (i) are 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutyramide.

[0040] These solvents can be used alone or in combination of two or more. Among these solvents, those with a boiling point of 160°C or higher are preferred, and propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, cyclohexanone, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, 2,5-dimethylhexane-1,6-diyl diacetate (DAH; cas, 89182-68-3), and 1,6-diacetoxyhexane (cas, 6222-17-9) are preferred. In particular, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutyramide are preferred.

[0041] [Crosslinking agent component] The resist underlayer film forming composition of the present invention may contain a crosslinking agent component. Examples of the crosslinking agent include melamine-based, substituted urea-based, and polymers thereof. A crosslinking agent having at least two crosslinking-forming substituents is preferred, and is a compound such as methoxymethylated glycoluril (e.g., tetramethoxymethylglycoluril), butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguwanamine, butoxymethylated benzoguwanamine, methoxymethylated urea, butoxymethylated urea, or methoxymethylated thiourea. Condensates of these compounds may also be used.

[0042] In addition, a crosslinking agent having high heat resistance can be used as the crosslinking agent. As the crosslinking agent having high heat resistance, a compound containing a crosslinking-forming substituent having an aromatic ring (e.g., a benzene ring, a naphthalene ring) in the molecule can be preferably used.

[0043] The compound may be a compound having a partial structure of the following formula (4), or a polymer or oligomer having a repeating unit of the following formula (5). [ka] Above R 11 , R 12 , R 13 , and R 14 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl groups mentioned above can be used.

[0044] Examples of the compounds, polymers and oligomers of formula (4) and formula (5) are shown below. [ka] [ka]

[0045] The above compounds are available as products of Asahi Yukizai Kogyo Co., Ltd. and Honshu Chemical Industry Co., Ltd. For example, among the above crosslinking agents, the compound of formula (4-23) is available from Honshu Chemical Industry Co., Ltd. under the product name TMOM-BP, and the compound of formula (4-24) is available from Asahi Yukizai Kogyo Co., Ltd. under the product name TM-BIP-A. The amount of the crosslinking agent added varies depending on the coating solvent used, the base substrate used, the required solution viscosity, the required film shape, etc., but is 0.001% by mass or more, 0.01% by mass or more, 0.05% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and 80% by mass or less, 50% by mass or less, 40% by mass or less, 20% by mass or less, or 10% by mass or less, based on the total solid content. These crosslinking agents may cause a crosslinking reaction by self-condensation, but when crosslinkable substituents are present in the above-mentioned polymer of the present invention, they can cause a crosslinking reaction with the crosslinkable substituents.

[0046] [Acid and / or acid generator] The resist underlayer film forming composition of the present invention may contain an acid and / or an acid generator. Examples of the acid include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, pyridinium phenolsulfonic acid, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid. The amount of the acid to be used is usually 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.01 to 5% by mass, based on the total solid content.

[0047] The acid generator includes a thermal acid generator and a photoacid generator. Examples of thermal acid generators include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, K-PURE (registered trademark) CXC-1612, CXC-1614, TAG-2172, TAG-2179, TAG-2678, TAG2689, and TAG2700 (manufactured by King Industries), as well as SI-45, SI-60, SI-80, SI-100, SI-110, and SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd.), and other organic sulfonic acid alkyl esters.

[0048] Photoacid generators generate acid when the resist is exposed to light. This allows the acidity of the underlayer to be adjusted. This is one way to match the acidity of the underlayer to that of the upper resist. Adjusting the acidity of the underlayer also allows the pattern shape of the resist formed in the upper layer to be adjusted. Examples of the photoacid generator contained in the resist underlayer film forming composition of the present invention include an onium salt compound, a sulfonimide compound, and a disulfonyldiazomethane compound.

[0049] Examples of the onium salt compound include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoronormal butanesulfonate, diphenyliodonium perfluoronormal octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoronormal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0050] Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0051] Examples of the disulfonyldiazomethane compound include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0052] The acid generators may be used alone or in combination of two or more. When an acid generator is used, the proportion thereof is 0.01 to 10 parts by mass, or 0.1 to 8 parts by mass, or 0.5 to 5 parts by mass, relative to 100 parts by mass of the solid content of the resist underlayer film forming composition.

[0053] [Other ingredients] The resist underlayer film forming composition of the present invention may contain a surfactant in order to prevent pinholes, striations, etc., and to further improve coating properties against surface unevenness. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate ... Examples of suitable surfactants include nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorosurfactants such as F-TOP EF301, EF303, and EF352 (trade names, manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, R-40, R-40N, and R-40LM (trade names, manufactured by DIC Corporation); Fluorad FC430 and FC431 (trade names, manufactured by Sumitomo 3M Limited); Asahiguard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (trade names, manufactured by Asahi Glass Co., Ltd.); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of these surfactants is usually 2.0% by mass or less, preferably 1.0% by mass or less, based on the total solid content of the resist underlayer film material. These surfactants may be used alone or in combination of two or more. When a surfactant is used, the proportion is 0.0001 to 5 parts by mass, or 0.001 to 1 part by mass, or 0.01 to 0.5 parts by mass, based on 100 parts by mass of the solid content of the resist underlayer film forming composition.

[0054] The resist underlayer film forming composition of the present invention may contain a light absorbing agent, a rheology control agent, an adhesion promoter, etc. The rheology control agent is effective in improving the fluidity of the underlayer film forming composition. The adhesion promoter is effective in improving the adhesion between the semiconductor substrate or resist and the underlayer film.

[0055] Examples of the light absorbing agent include commercially available light absorbing agents described in "Technology and Market of Industrial Dyes" (CMC Publishing) and "Dye Handbook" (edited by the Society of Organic Synthesis Chemistry), such as CI Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114 and 124; CI Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72 and 73; CI Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; CI Disperse Violet 43; CI Disperse Blue 96; CI Fluorescent Brightening Agent Suitable examples of the light absorbing agent that can be used include 112, 135, and 163; CI Solvent Orange 2 and 45; CI Solvent Red 1, 3, 8, 23, 24, 25, 27, and 49; CI Pigment Green 10; and CI Pigment Brown 2. The light absorbing agent is usually blended in an amount of 10% by mass or less, and preferably 5% by mass or less, based on the total solid content of the resist underlayer film-forming composition.

[0056] The rheology control agent is mainly added to improve the flowability of the resist underlayer film forming composition, and particularly in the baking process, to improve the film thickness uniformity of the resist underlayer film and to enhance the filling property of the resist underlayer film forming composition into the hole.Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate, adipic acid derivatives such as di-normal butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyl decyl adipate, maleic acid derivatives such as di-normal butyl maleate, diethyl maleate, and dinonyl maleate, oleic acid derivatives such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate, and stearic acid derivatives such as normal butyl stearate and glyceryl stearate.These rheology control agents are usually blended at a ratio of less than 30% by mass based on the total solid content of the resist underlayer film forming composition.

[0057] The adhesion promoter is added mainly for the purpose of improving the adhesion between the substrate or resist and the resist underlayer film forming composition, and in particular to prevent the resist from peeling off during development. Specific examples include chlorosilanes such as trimethylchlorosilane, dimethylmethylolchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane, alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylmethylolethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane, silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylimidazole, and methyloltrimethylsilane. Examples of the adhesive auxiliary include silanes such as chlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane, heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, and mercaptopyrimidine, and ureas such as 1,1-dimethylurea and 1,3-dimethylurea, or thiourea compounds. These adhesive auxiliary agents are usually blended in an amount of less than 5% by mass, preferably less than 2% by mass, based on the total solid content of the resist underlayer film-forming composition.

[0058] The solid content of the resist underlayer film forming composition according to the present invention is usually 0.1 to 70 mass%, preferably 0.1 to 60 mass%. The solid content is the content of all components excluding the solvent from the resist underlayer film forming composition. The proportion of the polymer in the solid content is preferably 1 to 100 mass%, 1 to 99.9 mass%, 50 to 99.9 mass%, 50 to 95 mass%, and 50 to 90 mass%, in that order.

[0059] One of the measures for evaluating whether a resist underlayer film-forming composition is in a uniform solution state is to observe its passability through a specific microfilter. The resist underlayer film-forming composition of the present invention passes through a microfilter having a pore size of 0.2 μm and exhibits a uniform solution state.

[0060] Examples of the microfilter material include fluororesins such as PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PE (polyethylene), UPE (ultra-high molecular weight polyethylene), PP (polypropylene), PSF (polysulfone), PES (polyethersulfone), and nylon, with PTFE (polytetrafluoroethylene) being preferred.

[0061] [Method of manufacturing resist underlayer film and semiconductor device] Hereinafter, a method for producing a resist underlayer film and a semiconductor device using the resist underlayer film forming composition according to the present invention will be described.

[0062] The resist underlayer film forming composition of the present invention is applied onto a substrate (e.g., a silicon wafer substrate, a silicon / silicon dioxide-coated substrate, a silicon nitride substrate, a glass substrate, an ITO substrate, a polyimide substrate, and a substrate coated with a low dielectric constant material (low-k material)) used in the manufacture of a semiconductor device by a suitable application method such as a spinner or a coater, and then baked to form a resist underlayer film. The baking conditions are appropriately selected from a baking temperature of 80°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150°C to 350°C and the baking time is 0.5 to 2 minutes. Here, the thickness of the underlayer film formed is, for example, 10 to 1000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.

[0063] In addition, an inorganic resist underlayer film (hard mask) can be formed on the organic resist underlayer film according to the present invention. For example, a silicon-containing resist underlayer film (inorganic resist underlayer film) forming composition described in WO2009 / 104552A1 can be formed by spin coating, or a Si-based inorganic material film can be formed by a CVD method or the like.

[0064] Furthermore, by applying the resist underlayer film forming composition according to the present invention onto a semiconductor substrate having a portion with a step and a portion without a step (a so-called stepped substrate), and baking the substrate, a resist underlayer film can be formed in which the step between the portion with a step and the portion without a step is within the range of 3 to 70 nm.

[0065] Then, a resist film, for example, a photoresist layer, is formed on the resist underlayer film. The photoresist layer can be formed by a well-known method, that is, by coating a photoresist composition solution on the underlayer film and baking it. The thickness of the photoresist is, for example, 50 to 10,000 nm, or 100 to 2,000 nm, or 200 to 1,000 nm.

[0066] The photoresist formed on the resist underlayer film is not particularly limited as long as it is sensitive to the light used for exposure. Either negative photoresist or positive photoresist can be used. There are positive photoresists made of novolac resin and 1,2-naphthoquinone diazide sulfonic acid ester, chemically amplified photoresists made of a binder having a group that decomposes with acid to increase the alkaline dissolution rate and a photoacid generator, chemically amplified photoresists made of a low molecular compound that decomposes with acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, and chemically amplified photoresists made of a binder having a group that decomposes with acid to increase the alkaline dissolution rate, a low molecular compound that decomposes with acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator. Examples of such photoresists include APEX-E (trade name) manufactured by Shipley, PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. Further, there can be mentioned fluorine-containing polymer photoresists as described in, for example, Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0067] Next, a resist pattern is formed by irradiation with light or electron beams and development. First, exposure is performed through a predetermined mask. Near ultraviolet light, far ultraviolet light, or extreme ultraviolet light (for example, EUV (wavelength 13.5 nm)) is used for exposure. Specifically, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F2 excimer laser (wavelength 157 nm), etc. can be used. Among these, ArF excimer laser (wavelength 193 nm) and EUV (wavelength 13.5 nm) are preferred. After exposure, post exposure bake can be performed as necessary. Post exposure bake is performed under conditions appropriately selected from a heating temperature of 70°C to 150°C and a heating time of 0.3 to 10 minutes.

[0068] In addition, in the present invention, a resist for electron beam lithography can be used instead of a photoresist as a resist. Either a negative type or a positive type can be used as the electron beam resist. There are chemically amplified resists consisting of an acid generator and a binder having a group that decomposes with an acid to change the alkaline dissolution rate, a chemically amplified resist consisting of an alkali-soluble binder, an acid generator, and a low molecular weight compound that decomposes with an acid to change the alkaline dissolution rate of the resist, a chemically amplified resist consisting of an acid generator, a binder having a group that decomposes with an acid to change the alkaline dissolution rate, and a low molecular weight compound that decomposes with an acid to change the alkaline dissolution rate of the resist, a non-chemically amplified resist consisting of a binder having a group that decomposes with an electron beam to change the alkaline dissolution rate, and a non-chemically amplified resist consisting of a binder having a site that is cut by an electron beam to change the alkaline dissolution rate. When these electron beam resists are used, a resist pattern can be formed in the same way as when a photoresist is used with an electron beam as the irradiation source.

[0069] Next, development is performed with a developer, whereby, for example, when a positive photoresist is used, the photoresist in the exposed portion is removed, and a photoresist pattern is formed. Examples of the developing solution include an aqueous solution of an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an aqueous solution of a quaternary ammonium hydroxide such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, or choline, or an aqueous solution of an amine such as ethanolamine, propylamine, or ethylenediamine. Furthermore, a surfactant or the like can be added to these developing solutions. The developing conditions are appropriately selected from a temperature of 5 to 50° C. and a time of 10 to 600 seconds.

[0070] Then, the inorganic underlayer film (middle layer) is removed using the pattern of the photoresist (upper layer) thus formed as a protective film, and then the organic underlayer film (lower layer) is removed using the film consisting of the patterned photoresist and the inorganic underlayer film (middle layer) as a protective film. Finally, the semiconductor substrate is processed using the patterned inorganic underlayer film (middle layer) and the organic underlayer film (lower layer) as protective films.

[0071] First, the inorganic underlayer film (intermediate layer) in the portion where the photoresist has been removed is removed by dry etching to expose the semiconductor substrate. For dry etching of the inorganic underlayer film, gases such as tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, chlorine trifluoride, chlorine, trichloroborane, and dichloroborane can be used. For dry etching of the inorganic underlayer film, it is preferable to use a halogen-based gas, and more preferable to use a fluorine-based gas. Examples of fluorine-based gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0072] Thereafter, the organic underlayer film is removed using the patterned photoresist and the inorganic underlayer film as a protective film. The organic underlayer film (underlayer) is preferably removed by dry etching with an oxygen-based gas. This is because the inorganic underlayer film, which contains a large amount of silicon atoms, is difficult to remove by dry etching with an oxygen-based gas.

[0073] Finally, the semiconductor substrate is processed, preferably by dry etching using a fluorine-based gas. Examples of fluorine-based gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0074] An organic anti-reflective coating can be formed on the resist underlayer before the formation of the photoresist. The anti-reflective coating composition used therein is not particularly limited, and can be arbitrarily selected from those conventionally used in the lithography process, and the anti-reflective coating can be formed by a conventional method, for example, coating with a spinner or coater and baking.

[0075] In the present invention, an organic underlayer film is formed on a substrate, and then an inorganic underlayer film is formed thereon, and a photoresist is further coated thereon. This narrows the pattern width of the photoresist, and even if the photoresist is thinly coated to prevent pattern collapse, the substrate can be processed by selecting an appropriate etching gas. For example, a fluorine-based gas that has a sufficiently high etching rate for the photoresist can be used as an etching gas to process the resist underlayer film, a fluorine-based gas that has a sufficiently high etching rate for the inorganic underlayer film can be used as an etching gas to process the substrate, and an oxygen-based gas that has a sufficiently high etching rate for the organic underlayer film can be used as an etching gas to process the substrate.

[0076] The resist underlayer film formed from the resist underlayer film forming composition may also have absorption of light depending on the wavelength of the light used in the lithography process. In such a case, it can function as an anti-reflective film having the effect of preventing reflected light from the substrate. Furthermore, the underlayer film formed from the resist underlayer film forming composition of the present invention can also function as a hard mask. The underlayer film of the present invention can also be used as a layer for preventing interaction between the substrate and the photoresist, a layer having a function of preventing the adverse effect on the substrate of the material used in the photoresist or the substance generated during exposure to the photoresist, a layer having a function of preventing the diffusion of the substance generated from the substrate during heating and baking into the upper photoresist, and a barrier layer for reducing the poisoning effect of the photoresist layer due to the dielectric layer of the semiconductor substrate.

[0077] In addition, the underlayer film formed from the resist underlayer film forming composition can be applied to a substrate having a via hole used in a dual damascene process, and can be used as a filling material capable of filling the hole without gaps. Also, the composition can be used as a planarizing material for planarizing the surface of a semiconductor substrate having irregularities. EXAMPLES

[0078] Specific examples of the resist underlayer film forming composition of the present invention will be described below using the following examples, but the present invention is not limited thereto.

[0079] The apparatus used to measure the weight average molecular weight of the reaction products obtained in the following synthesis examples is shown below. Equipment: Tosoh Corporation HLC-8320GPC GPC column: TSKgel Super-MultiporeHZ-N (2 columns) Column temperature: 40℃ Flow rate: 0.35ml / min Eluent:THF Standard sample: polystyrene

[0080] The chemical structures (examples) and abbreviations of the main raw materials used are as follows: [ka] [ka] [ka]

[0081] <Synthesis Example 1> 26.07 g of propylene glycol monomethyl ether (hereinafter abbreviated as PGME in this specification) was mixed with 6.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 4.91 g of 1-naphthalenecarboxylic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 0.26 g of ethyltriphenylphosphonium bromide as a catalyst, and the mixture was reacted at 140° C. for 24 hours to obtain a solution containing a reaction product. 12.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 12.00 g of cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) were added, stirred at 25° C. to 30° C. for 4 hours, and then filtered. The resulting reaction product was subjected to GPC analysis and was found to have a weight average molecular weight, calculated in terms of standard polystyrene, of 770. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (1). [ka]

[0082] <Synthesis Example 2> 26.07 g of PGME was mixed with 6.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 6.33 g of 9-anthracenecarboxylic acid (manufactured by Midori Kagaku Co., Ltd.), and 0.26 g of ethyltriphenylphosphonium bromide as a catalyst, and the mixture was reacted at 140° C. for 24 hours to obtain a solution containing a reaction product. 13.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 13.00 g of cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) were added, stirred at 25° C. to 30° C. for 4 hours, and then filtered. The resulting reaction product was subjected to GPC analysis and was found to have a weight average molecular weight, calculated in terms of standard polystyrene, of 830. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (2). [ka]

[0083] <Synthesis Example 3> 22.74 g of PGME was mixed with 6.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 3.48 g of benzoic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 0.26 g of ethyltriphenylphosphonium bromide as a catalyst, and the mixture was reacted at 140° C. for 24 hours to obtain a solution containing a reaction product. 10.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 10.00 g of cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) were added, stirred at 25° C. to 30° C. for 4 hours, and then filtered. The resulting reaction product was subjected to GPC analysis and was found to have a weight average molecular weight, calculated in terms of standard polystyrene, of 750. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (4). [ka]

[0084] <Synthesis Example 4> 25.83 g of PGME was mixed with 5.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 5.85 g of 1-pyrene carboxylic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 0.22 g of ethyl triphenylphosphonium bromide as a catalyst, and the mixture was reacted at 140° C. for 24 hours to obtain a solution containing a reaction product. 11.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) and 11.00 g of cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) were added, stirred at 25° C. to 30° C. for 4 hours, and then filtered. The resulting reaction product was subjected to GPC analysis and was found to have a weight average molecular weight, calculated in terms of standard polystyrene, of 720. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (5). [ka]

[0085] <Comparative Synthesis Example 1> 17.67 g of propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA in this specification), 5.00 g of EHPE-3150 (manufactured by Daicel Corporation), 3.11 g of 9-anthracene carboxylic acid, 2.09 g of benzoic acid, and 0.62 g of ethyl triphenylphosphonium bromide were added to 7.57 g of PGME, and the mixture was heated under reflux for 13 hours under a nitrogen atmosphere. 16 g of a cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) and 16 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Corporation) were added to the resulting solution, and the mixture was stirred at 25°C to 30°C for 4 hours and then filtered. The reaction product obtained was subjected to GPC analysis and found to have a weight average molecular weight, calculated in terms of standard polystyrene, of 4,700. The reaction product obtained is presumed to be a copolymer having a structural unit represented by the following formula (3). [ka]

[0086] [Preparation of resist underlayer film-forming composition] <Example 1> 4.90 g of a solution containing 1.26 g of the copolymer obtained in Synthesis Example 1 (solvent: PGME, solid content: 25.74% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of a 1% by mass PGME solution of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.), 6.66 g of PGME, 5.54 g of PGMEA, and 0.13 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 7.7% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0087] <Example 2> 4.63 g of a solution containing 1.26 g of the copolymer obtained in Synthesis Example 2 (solvent: PGME, solid content: 27.23% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of a 1% by mass PGME solution of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.), 6.93 g of PGME, 5.54 g of PGMEA, and 0.13 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 7.7% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0088] <Example 3> 5.06 g of a solution containing 1.26 g of the copolymer obtained in Synthesis Example 3 (solvent: PGME, solid content: 24.95% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of a 1% by mass PGME solution of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.), 6.51 g of PGME, 5.54 g of PGMEA, and 0.13 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 7.7% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter having a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0089] <Example 4> 4.19 g of a solution containing 1.26 g of the copolymer obtained in Synthesis Example 4 (solvent: PGME, solid content: 30.12% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of a 1% by mass PGME solution of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.), 7.37 g of PGME, 5.54 g of PGMEA, and 0.13 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 7.7% by mass solution. The solution was filtered using a polytetrafluoroethylene microfilter having a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0090] <Comparative Example 1> 19.52 g of a solution containing 4.51 g of the copolymer obtained in Comparative Synthesis Example 1 (solvent is the PGME / PGMEA mixed solvent used in synthesis, solid content is 23.26 mass%) was mixed with 1.14 g of tetramethoxymethylglycoluril (product name: POWDERLINK [registered trademark] 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 3.41 g of a 1 mass% PGME solution of pyridinium p-toluenesulfonate, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1 mass% PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30) to obtain a 6.35 mass% solution. The solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a resist underlayer film forming composition.

[0091] [Photoresist solvent elution test] The resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1 were each applied onto a silicon wafer using a spinner. Then, the wafer was baked on a hot plate for 1 minute at the temperature shown in Table 1 below to form a resist underlayer film (film thickness 0.2 μm). These resist underlayer films were immersed in a PGME / PGMEA mixed solvent (mass mixing ratio 70 / 30), which is a solvent used in photoresist solutions, to confirm that they were insoluble in the solvent, and the results are shown in Table 1 below with "○".

[0092] [Optical parameter testing] The resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1 were each applied onto a silicon wafer by a spinner. Then, the resist underlayer film (film thickness 0.2 μm) was formed by baking on a hot plate for 1 minute at the temperature shown in Table 1 below. The refractive index (n value) and attenuation coefficient (k value) of these resist underlayer films at a wavelength of 193 nm were measured using an optical ellipsometer (JA Woollam, VUV-VASE VU-302). The results are shown in Table 1 below. In order for the resist underlayer film to have a sufficient antireflection function, the k value at a wavelength of 193 nm is preferably 0.1 or more and 0.4 or less.

[0093] [Measurement of Dry Etching Rate] Using the resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1, resist underlayer films were formed on silicon wafers by the same method as above. The dry etching rates of these resist underlayer films were measured using a Samco Inc. RIE system under conditions using CF4 as dry etching gas. The dry etching rate of each resist underlayer film was calculated when the dry etching rate of Comparative Example 1 was set to 1.00. The results are shown in Table 1 below as "relative dry etching rate". The dry etching rates of the resist underlayer films formed using the resist underlayer film forming compositions prepared in Examples 1 to 2 were sufficiently slower than the dry etching rate of Comparative Example 1, and therefore it was shown that substrate processing was easy using the resist underlayer film forming composition as a mask.

[0094] [Table 1]

[0095] [Embeddability evaluation] The embedding property was confirmed in a dense pattern area with a SiO2 substrate having a thickness of 200 nm, a trench width of 50 nm, and a pitch of 100 nm. Each of the resist underlayer film forming compositions prepared in Examples 1 to 2 and Comparative Examples 1 to 3 was applied onto the substrate, and then baked under predetermined conditions to form a resist underlayer film of about 200 nm. The planarization property of this substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation, and the presence or absence of the resist underlayer film forming composition filling the inside of the pattern was confirmed. Examples 1 to 2 and Comparative Examples 2 to 3 were good, but voids were confirmed in Comparative Example 1.

[0096] [Coating test for uneven substrate] To evaluate the step coverage, a comparison was made between the coating thickness of a dense pattern area (DENSE) with a trench width of 50 nm and a pitch of 100 nm and an open area (OPEN) with no pattern formed on a 200 nm thick SiO2 substrate. Each of the resist underlayer film forming compositions of Examples 1 and 2 and Comparative Examples 1 to 3 was applied to the above substrate in a thickness of 150 nm, and then baked at a predetermined temperature. The step coverage of this substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High-Technologies Corporation, and the planarization was evaluated by measuring the film thickness difference between the dense area (patterned area) and the open area (no pattern area) of the step substrate (the coating step between the dense area and the open area, which is called Bias). The film thickness and coating step values ​​in each area are shown in Table 2. The smaller the Bias value, the higher the planarization.

[0097] [Table 2] [Industrial Applicability]

[0098] According to the present invention, there are provided a resist underlayer film-forming composition that exhibits high etching resistance, a good dry etching rate ratio and optical constants, has good coverage even for so-called stepped substrates, has a small film thickness difference after embedding, and is capable of forming a flat film; a resist underlayer film using the resist underlayer film-forming composition; and a method for manufacturing a semiconductor device.

Claims

1. A resist underlayer film-forming composition comprising a polymer having a partial structure represented by the following formula (1) and a weight average molecular weight Mw of 2,200 or less, and a solvent, The polymer having a partial structure represented by the formula (1) is 【Chemistry 4】 or 【Chemistry 5】 and, It is a reaction product with an aromatic carboxylic acid having 6 to 20 carbon atoms, which may be substituted. A resist underlayer film forming composition. 【Chemistry 20】 (wherein Ar represents an aromatic group having 6 to 20 carbon atoms which may be substituted).

2. 2. The resist underlayer film forming composition according to claim 1, wherein Ar in formula (1) is a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof.

3. 2. The resist underlayer film forming composition according to claim 1, wherein Ar in formula (1) is a naphthyl group, an anthracenyl group, or a combination thereof.

4. The resist underlayer film forming composition according to any one of claims 1 to 3, further comprising a crosslinking agent.

5. The resist underlayer film forming composition according to any one of claims 1 to 3, further comprising an acid and / or an acid generator.

6. The resist underlayer film forming composition according to claim 1 , wherein the solvent has a boiling point of 160° C. or higher.

7. A resist underlayer film, which is a fired product of a coating film comprising the resist underlayer film forming composition according to any one of claims 1 to 6.

8. A step of forming a resist underlayer film on a semiconductor substrate using the resist underlayer film forming composition according to any one of claims 1 to 6; forming a resist film on the formed resist underlayer film; A step of forming a resist pattern by irradiating the formed resist film with light or an electron beam and developing it; A step of etching and patterning the resist underlayer film through the formed resist pattern; and A process for processing a semiconductor substrate through a patterned resist underlayer film. A method for manufacturing a semiconductor device comprising the steps of:

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