Resist underlayer film-forming composition

Abstract

The present invention provides a resist underlayer film-forming composition that can provide good coverage even on uneven substrates, has small film thickness differences after filling, and can form a flat film. It also provides a polymer that is an important component of the resist underlayer film-forming composition, a resist underlayer film formed using the resist underlayer film-forming composition, and a method for manufacturing a semiconductor device. The present invention provides a resist underlayer film-forming composition comprising a compound represented by the following formula (1) and a solvent: [Formula 1] TIFF2026041942000019.tif42168 (In the formula, Ar1, Ar2, Ar3, and Ar4 each independently represent an optionally substituted monovalent aromatic hydrocarbon group, and a, b, c, and d each represent 0 or 1, and a+b+c+d=1.)

Description

[Technical Field]

[0001] The present invention relates to a resist underlayer film-forming composition that exhibits a good dry etching rate ratio and optical constants, has good coverage even on so-called uneven substrates, has a small film thickness difference after filling, and is capable of forming a flat film; a polymer that is an important component of the resist underlayer film-forming composition; a resist underlayer film formed 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 have been required to function as anti-reflective coatings, particularly for short wavelength exposure, have appropriate optical constants, and also have etching resistance during substrate processing. For this reason, the use of polymers having repeating units containing benzene rings 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] To achieve thinner resist layers as resist patterns become finer, a lithography process is known in which at least two resist underlayer films are formed and used as a mask material. This involves providing at least one organic film (underlayer organic film) and at least one inorganic underlayer film on a semiconductor substrate, patterning the inorganic underlayer film using a resist pattern formed on an upper resist film as a mask, and then patterning the lower organic film using the pattern as a mask. This method is said to be capable of forming patterns with high aspect ratios. Examples of materials for forming the at least two resist underlayer films include combinations of organic resins (e.g., acrylic resins, novolac resins) and inorganic materials (e.g., silicon resins (e.g., organopolysiloxanes), inorganic silicon compounds (e.g., SiON, SiO2), etc.). In recent years, double patterning technology, which involves two lithography processes and two etching processes to obtain a single pattern, has been widely applied, with the above-mentioned multilayer process being used in each step. In this case, the organic film formed after the initial pattern is required to have the property of flattening steps.

[0005] However, when the resist pattern formed on the substrate to be processed has differences in height or density, that is, a stepped substrate, the composition for forming a resist underlayer film does not sufficiently cover the steps, resulting in a large difference in film thickness after filling, making it difficult to form a flat film.

[0006] The present invention has been made with the aim of solving these 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 on so-called uneven substrates, has small film thickness differences after filling, and is capable of forming a flat film. Another aim of the present invention is to provide a polymer that is an important component of the resist underlayer film-forming composition, a resist underlayer film formed using the resist underlayer film-forming composition, and a method for producing a semiconductor device. [Means for solving the problem]

[0007] The present invention encompasses the following. The present invention provides, in a first aspect, a resist comprising a compound represented by the following formula (1) and a solvent: The present invention relates to an underlayer film-forming composition. [ka] (In the formula, Ar1, Ar2, Ar3, and Ar4 each independently represent an optionally substituted monovalent aromatic hydrocarbon group, and a, b, c, and d each represent 0 or 1, and a+b+c+d=1.) In a second aspect, the present invention relates to the resist underlayer film-forming composition according to the first aspect, wherein the aromatic hydrocarbon group is a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof. In a third aspect, the present invention relates to the resist underlayer film-forming composition according to the first or second aspect, in which the aromatic hydrocarbon group is unsubstituted. In a fourth aspect, the present invention relates to the resist underlayer film-forming composition according to the first or second aspect, wherein the aromatic hydrocarbon group is an aromatic hydrocarbon group that is bonded to an alkyl substituent with or without oxygen, as represented by the following formula (2): [ka] (Ar represents an aromatic hydrocarbon group, n is 0 or 1, and R is an alkyl group having 1 to 19 carbon atoms.) In a fifth aspect, the present invention relates to the resist underlayer film-forming composition according to any one of the first to fourth aspects, in which the solvent has a boiling point of 160° C. or higher. In a sixth aspect, the present invention relates to a resist underlayer film, which is a baked product of a coating film made of the resist underlayer film-forming composition according to any one of the first to fifth aspects. According to a seventh aspect, the present invention provides a method for forming a resist underlayer film on a semiconductor substrate using the resist underlayer film-forming composition according to any one of the first to fifth aspects; 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 using the formed resist pattern; and A process for processing a semiconductor substrate using a patterned resist underlayer film. The present invention relates to a method for manufacturing a semiconductor device including the steps of: [Effects of the Invention]

[0008]

[0009] Conventionally, when a polymer in a resist underlayer film-forming composition contains an aromatic hydrocarbon at the end of its skeleton, the resist underlayer film-forming composition has the drawback of insufficient coverage on uneven substrates, large coating unevenness, and poor planarization. However, the present inventors have discovered that coating unevenness can be effectively suppressed only by using a compound in which the polymer skeleton contains a large amount of aromatic hydrocarbon at the end and which has a relatively low molecular weight, and have thereby completed the present invention. The resist underlayer film forming composition of the present invention has a good dry etching rate ratio and optical Not only does it have a constant, but the resulting resist underlayer film also has good coverage even on so-called uneven substrates, has small film thickness differences 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 in a lithography process in which at least two resist underlayer films are formed to reduce the resist film thickness, and the resist underlayer film is used as an etching mask. Furthermore, the resist underlayer film-forming composition of the present invention has an appropriate antireflection effect and a high dry etching rate for a resist film, and therefore can be used in processing substrates. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Resist underlayer film-forming composition] The resist underlayer film-forming composition according to the present invention is a resist underlayer film-forming composition containing a compound represented by the following formula (1) and a solvent. [ka] (In the formula, Ar1, Ar2, Ar3, and Ar4 each independently represent an optionally substituted aromatic hydrocarbon group, a, b, c, and d each represent 0 or 1, and a+b+c+d=1.)

[0010] The aromatic hydrocarbon group may be a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof. The aromatic hydrocarbon group may be unsubstituted or may be bonded to an alkyl substituent with or without oxygen.

[0011] The aromatic hydrocarbon group having an alkyl substituent is represented by the following formula (2), where Ar represents an aromatic hydrocarbon group, n is 0 or 1, and R is a substituent. [ka]

[0012] Specifically, Ar may be a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof. R represents an alkyl group which may have a branch, and some of the hydrogen atoms may be substituted with a hydroxyl group, a nitro group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom).

[0013] Examples of the alkyl group include alkyl groups having 1 to 19 carbon atoms, such as 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, a cyclobutyl group, a 1-methyl-cyclopropyl group, a 2-methyl-cyclopropyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, a 1- Ethyl-n-propyl, cyclopentyl, 1-methyl-cyclobutyl, 2-methyl-cyclobutyl, 3-methyl-cyclobutyl, 1,2-dimethyl-cyclopropyl, 2,3-dimethyl-cyclopropyl, 1-ethyl-cyclopropyl, 2-ethyl-cyclopropyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl, 3-methyl-n-pentyl, 4-methyl-n-pentyl, 1,1-dimethyl-n-butyl, 1,2-dimethyl-n-butyl, 1,3-dimethyl-n-butyl, 2,2-dimethyl n-butyl, 2,3-dimethyl-n-butyl, 3,3-dimethyl-n-butyl, 1-ethyl-n-butyl, 2-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, 1-ethyl-2-methyl-n-propyl, n-heptyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n -heptadecyl, 2-heptyl-undecyl, n-octadecyl, n-nonadecyl, 5,9-dimethyl-2-(6-methylheptyl)decyl, cyclohexyl, 1-methyl-cyclopentyl, 2-methyl-cyclopentyl, 3-methyl-cyclopentyl, 1-ethyl-cyclobutyl, 2-ethyl-cyclobutyl, 3-ethyl-cyclobutyl, 1,2-dimethyl-cyclobutyl, 1,3-dimethyl-cyclobutyl, 2,2-dimethyl-cyclobutyl, 2,3-dimethyl-cyclobutyl, 2,4-dimethyl-cyclobutyl Examples of such groups include cyclobutyl, 3,3-dimethyl-cyclobutyl, 1-n-propyl-cyclopropyl, 2-n-propyl-cyclopropyl, 1-i-propyl-cyclopropyl, 2-i-propyl-cyclopropyl, 1,2,2-trimethyl-cyclopropyl, 1,2,3-trimethyl-cyclopropyl, 2,2,3-trimethyl-cyclopropyl, 1-ethyl-2-methyl-cyclopropyl, 2-ethyl-1-methyl-cyclopropyl, 2-ethyl-2-methyl-cyclopropyl, and 2-ethyl-3-methyl-cyclopropyl groups.

[0014] [solvent]

[0033] The solvent for the resist underlayer film-forming composition of the present invention is not particularly limited, as long as it can dissolve the reaction product. In particular, since the resist underlayer film-forming composition of 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 consideration its coating performance.

[0015] 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, 3-methoxypropanol, methyl 2-hydroxypropanol, methyl 3-methoxy ... Methyl propionate, 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 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, 2-hydroxypropyl Examples of suitable solvents include methyl 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-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.

[0016] In addition, the following compounds described in WO2018 / 131562A1 can also be used. [ka] (R in formula (i) 1 , R 2 and R 3each 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.

[0017] Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups that may or may not have a substituent, such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and 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 even more preferably an alkyl group having 1 to 4 carbon atoms.

[0018] Examples of alkyl groups having 1 to 20 carbon atoms interrupted by oxygen atoms, sulfur atoms, or amide bonds include those containing the structural units -CH2-O-, -CH2-S-, -CH2-NHCO-, or -CH2-CONH-. The alkyl group may contain one or more -O-, -S-, -NHCO-, or -CONH- units. Alkyl groups having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO-, or -CONH- units Specific examples of the substituted aryl group 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, and the like, and further include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, or an octadecyl group, each of which is substituted with 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 methylaminocarbonyl group, an ethylaminocarbonyl group, or the like. Preferred are methoxy, ethoxy, methylthio and ethylthio groups, and more preferred are methoxy and ethoxy groups.

[0019] These solvents have a relatively high boiling point, and are therefore effective in imparting high embedding properties and high planarization properties to the resist underlayer film-forming composition.

[0020] Specific examples of preferred compounds represented by formula (i) are shown below. [ka]

[0021] Among the above, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and The following formula: [ka] Compounds represented by the formula (i) are preferably 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutyramide.

[0022] These solvents can be used alone or in combination. Among these solvents, those with a boiling point of 160°C or higher are preferred, including 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). Particularly preferred are propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutyramide.

[0023] [Crosslinking agent component] The resist underlayer film-forming composition of the present invention may contain a crosslinker component. Examples of such crosslinkers include melamine-based crosslinkers, substituted urea-based crosslinkers, and polymers thereof. A crosslinker having at least two crosslink-forming substituents is preferred, 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.

[0024] In addition, a crosslinking agent having high heat resistance can be used as the crosslinking agent. As a crosslinking agent having high heat resistance, a compound containing a crosslink-forming substituent having an aromatic ring (e.g., a benzene ring or a naphthalene ring) in the molecule can be preferably used.

[0025] This 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 R11 , R 12 , R 13 , and R 14 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms The alkyl groups are the same as those exemplified above. n1 represents an integer that satisfies 1≦n1≦6−n2, n2 represents an integer that satisfies 1≦n2≦5, n3 represents an integer that satisfies 1≦n3≦4−n4, and n4 represents an integer that satisfies 1≦n4≦3.

[0026] Examples of compounds having the partial structure of formula (4) are shown below. [ka] [ka]

[0027] The above compounds are available 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 (4-24) is available from Asahi Organic Chemicals Co., Ltd. under the trade name TM-BIP-A. The amount of 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 to 80 mass % of the total solid content, preferably 0.01 to 50 mass %, and more preferably 0.05 to 40 mass %. These crosslinking agents may undergo a crosslinking reaction by self-condensation, but when crosslinkable substituents are present in the above-mentioned reaction product of the present invention, they can undergo a crosslinking reaction with these crosslinkable substituents.

[0028] [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 acids 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, and benzoic acid. Examples of suitable carboxylic acids include hydroxybenzoic acid, naphthalenecarboxylic acid, and the like. 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 3% by mass, based on the total solid content.

[0029] Examples of the acid generator include 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), and 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.

[0030] Photoacid generators generate acid when the resist is exposed to light. This allows the acidity of the underlayer film to be adjusted. This is one way to match the acidity of the underlayer film to that of the upper layer resist. Adjusting the acidity of the underlayer film also allows for adjustment of the pattern shape of the upper layer resist. Examples of the photoacid generator contained in the resist underlayer film-forming composition of the present invention include onium salt compounds, sulfonimide compounds, and disulfonyldiazomethane compounds.

[0031] Examples of the onium salt compound include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-normal butanesulfonate, diphenyliodonium perfluoro-normal 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 nonafluoro-normal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0032] Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0033] Examples of disulfonyldiazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0034] The acid generators may be used singly or in combination of two or more. When an acid generator is used, the proportion thereof is 0.01 to 5 parts by mass, or 0.1 to 3 parts by mass, or 0.5 to 1 part by mass, relative to 100 parts by mass of the solid content of the resist underlayer film-forming composition.

[0035] [Other ingredients] The resist underlayer film-forming composition of the present invention is free from pinholes, striations, etc. In order to further improve the coating property against surface unevenness, a surfactant can be blended. 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 aryl 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, and polyoxyethylene 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; fluorine-containing surfactants 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 added 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 thereof 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.

[0036] The resist underlayer film-forming composition of the present invention may contain a light absorber, a rheology modifier, an adhesion promoter, etc. The rheology modifier 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.

[0037] 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 Synthetic 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; and CI Fluorescent Brightening Agent. Suitable examples of the light absorbent that can be used include 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 absorbent is typically blended in an amount of 10% by mass or less, and preferably 5% by mass or less, based on the total solids content of the resist underlayer film-forming composition.

[0038] The rheology control agent is added mainly to improve the fluidity of the resist underlayer film-forming composition, and particularly in the baking step, to improve the film thickness uniformity of the resist underlayer film and the filling ability of the resist underlayer film-forming composition into holes. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; di-n-butyl adipate; diisobutyl adipate; Examples of the rheology modifier include adipic acid derivatives such as di-n-butyl maleate, diethyl maleate, dinonyl maleate, etc., maleic acid derivatives such as di-n-butyl maleate, diethyl maleate, dinonyl maleate, etc., oleic acid derivatives such as methyl oleate, butyl oleate, tetrahydrofurfuryl oleate, etc., and stearic acid derivatives such as n-butyl stearate, glyceryl stearate, etc. These rheology modifiers are typically blended in an amount of less than 30% by mass based on the total solids content of the resist underlayer film-forming composition.

[0039] 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 particularly 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; methyloltrimethylsilane; and methyltrimethylsilane. Examples of suitable adhesion aids 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 urea or thiourea compounds such as 1,1-dimethylurea and 1,3-dimethylurea. These adhesion aids are typically blended in an amount of less than 5% by mass, and preferably less than 2% by mass, based on the total solids content of the resist underlayer film-forming composition.

[0040] The solids content of the resist underlayer film-forming composition according to the present invention is usually 0.1 to 70% by mass, preferably 0.1 to 60% by mass. The solids content is the content of all components of the resist underlayer film-forming composition excluding the solvent. The proportion of the reaction product in the solids content is preferably 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, in that order.

[0041] One measure 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 with a pore size of 0.1 μm and exhibits a uniform solution state.

[0042] Examples of the microfilter material include fluorine-based resins 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.

[0043] [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.

[0044] The resist underlayer film-forming composition of the present invention is applied onto a substrate used in the manufacture of a semiconductor device (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 low dielectric constant material (low-k material)-coated substrate, etc.) by an appropriate application method such as a spinner or coater, and then baked. A resist underlayer film is formed by baking. 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. The thickness of the underlayer film formed here is, for example, 10 to 1000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.

[0045] Furthermore, 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.

[0046] Furthermore, by applying the resist underlayer film-forming composition according to the present invention to a semiconductor substrate having a portion with a step and a portion without a step (a so-called stepped substrate) and baking it, a resist underlayer film can be formed in which the step between the portion with a step and the portion without a step is in the range of 3 to 70 nm.

[0047] A resist film, such as a photoresist layer, is then formed on the resist underlayer film. The photoresist layer can be formed by a well-known method, i.e., by coating a photoresist composition solution on the underlayer film and baking it. The photoresist film thickness is, for example, 50 to 10,000 nm, or 100 to 2,000 nm, or 200 to 1,000 nm.

[0048] The photoresist formed on the resist underlayer film is not particularly limited as long as it is sensitive to the light used for exposure. Both negative and positive photoresists can be used. Examples include positive photoresists composed of a novolak resin and a 1,2-naphthoquinone diazide sulfonic acid ester; chemically amplified photoresists composed of a binder having a group that decomposes in the presence of acid to increase the alkaline dissolution rate and a photoacid generator; chemically amplified photoresists composed of a low-molecular-weight compound that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; and chemically amplified photoresists composed of a binder having a group that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, a low-molecular-weight compound that decomposes in the presence of acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator. Examples include APEX-E (trade name) manufactured by Shipley Chemical Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. Further examples include fluorine-containing polymer photoresists such as those described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0049] 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, far ultraviolet, or extreme ultraviolet (e.g., EUV (wavelength 13.5 nm)) is used for exposure. Specifically, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), and F2 excimer laser (wavelength 157 nm) 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 also be performed as needed. The 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.

[0050] In the present invention, a resist for electron beam lithography can be used instead of a photoresist. Either a negative or positive type electron beam resist can be used. Examples include chemically amplified resists consisting of an acid generator and a binder having a group that decomposes in the presence of acid to change the alkaline dissolution rate; chemically amplified resists consisting of an alkali-soluble binder, an acid generator, and a low-molecular-weight compound that decomposes in the presence of acid to change the alkaline dissolution rate of the resist; chemically amplified resists consisting of an acid generator, a binder having a group that decomposes in the presence of acid to change the alkaline dissolution rate, and a low-molecular-weight compound that decomposes in the presence of acid to change the alkaline dissolution rate of the resist; non-chemically amplified resists consisting of a binder having a group that decomposes in the presence of an electron beam to change the alkaline dissolution rate; and non-chemically amplified resists consisting of a binder having a moiety that is cleaved by an electron beam to change the alkaline dissolution rate. When using these electron beam resists, resist patterns can be formed in the same way as when using a photoresist with an electron beam as the irradiation source.

[0051] Next, development is carried out 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 developer include aqueous alkaline solutions such as aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, and aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine. Furthermore, surfactants and the like can also be added to these developers. Development conditions are appropriately selected from a temperature of 5 to 50°C and a time of 10 to 600 seconds.

[0052] Then, the inorganic lower layer film (middle layer) is removed using the photoresist (upper layer) pattern thus formed as a protective film, and then the organic lower layer film (lower layer) is removed using the film consisting of the patterned photoresist and inorganic lower layer film (middle layer) as a protective film. Finally, the semiconductor substrate is processed using the patterned inorganic lower layer film (middle layer) and organic lower layer film (lower layer) as protective films.

[0053] First, the inorganic underlayer film (intermediate layer) in the area where the photoresist was removed is removed by dry etching to expose the semiconductor substrate. Gases such as tetrafluoromethane (CF), perfluorocyclobutane (C), perfluoropropane (C), 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. A halogen-based gas is preferably used for dry etching of the inorganic underlayer film, and a fluorine-based gas is more preferred. Examples of fluorine-based gases include tetrafluoromethane (CF), perfluorocyclobutane (C), perfluoropropane (C), trifluoromethane, and difluoromethane (CH).

[0054] Thereafter, the organic underlayer film is removed using the patterned photoresist and inorganic underlayer film as a protective film. The organic underlayer film (underlayer) is preferably removed by dry etching using an oxygen-based gas. This is because inorganic underlayer films containing a large amount of silicon atoms are difficult to remove by dry etching using an oxygen-based gas.

[0055] 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).

[0056] In addition, an organic anti-reflective coating is formed on the upper layer of the resist underlayer before the photoresist is formed. The antireflective coating composition used therein is not particularly limited, and any composition that has been conventionally used in lithography processes can be selected and used, and the antireflective coating can be formed by a conventional method, for example, coating with a spinner or coater and baking.

[0057] 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 then coated on top of that. This narrows the pattern width of the photoresist, and even if a thin layer of photoresist is applied 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, and 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.

[0058] The resist underlayer film formed from the resist underlayer film-forming composition may also absorb light depending on the wavelength of the light used in the lithography process. In such cases, it can function as an antireflective film that prevents light from being reflected 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 the function of preventing adverse effects on the substrate of materials used in the photoresist or substances generated during exposure of the photoresist, a layer having the function of preventing diffusion of substances generated from the substrate during heating and baking into an upper photoresist layer, and a barrier layer for reducing the poisoning effect of the photoresist layer due to a dielectric layer of the semiconductor substrate.

[0059] In addition, an underlayer film formed from the resist underlayer film-forming composition can be applied to a substrate having via holes formed therein for use in a dual damascene process, and can be used as a filling material capable of filling the holes without gaps. It can also be used as a planarizing material for planarizing the surface of an uneven semiconductor substrate. [Example]

[0060] 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.

[0061] The apparatus used to measure the weight-average molecular weight of the reaction products obtained in the following synthesis examples is shown below. Apparatus: 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

[0062] <Synthesis Example 1> To 45.54 g of propylene glycol monomethyl ether (hereinafter abbreviated as PGME in this specification), 80.00 g of a 29.9 wt % PGME solution (trade name: Epolead GT401, manufactured by Daicel Corporation), 7.47 g of benzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 11.12 g of 9-anthracenecarboxylic acid (manufactured by Midori Chemical Co., Ltd.), and 1.03 g of ethyltriphenylphosphonium bromide as a catalyst were added, and the mixture was reacted at 140°C for 24 hours to obtain a solution containing the reaction product. An anion exchange resin (trade name: Dowex [registered trademark]) was added. ]MONOSPHERE (registered trademark) 550A, Muromachi Technos Co., Ltd.) 43.55 g and cation exchange resin (product name: Amberlyst (registered trademark) 15JWET, Organo Corporation) 43.55 g were added, stirred at 25 to 30°C for 4 hours, and then filtered. GPC analysis of the resulting reaction product revealed that the weight average molecular weight, calculated in terms of standard polystyrene, was 1400. The resulting reaction product was presumed to be a copolymer having a structural unit represented by the following formula (A). [ka] (a, b, c, and d are each 0 or 1, and a+b+c+d=1.)

[0063] <Synthesis Example 2> 7.57 g of PGME was mixed with 17.67 g of PGMEA, 5.00 g of EHPE-3150 (manufactured by Daicel Corporation), 3.11 g of 9-anthracenecarboxylic acid, 2.09 g of benzoic acid, and 0.62 g of ethyltriphenylphosphonium bromide as a catalyst, and the mixture was heated under reflux for 13 hours under a nitrogen atmosphere. 16 g of a cation exchange resin (product name: Amberlyst® 15JWET, Organo Corporation) and 16 g of anion exchange resin (product name: Dowex® MONOSPHERE® 550A, Muromachi Technos Co., Ltd.) were added to the resulting solution, stirred at 25 to 30°C for 4 hours, and then filtered. GPC analysis of the resulting reaction product revealed that the weight average molecular weight, calculated in terms of standard polystyrene, was 4,700. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (B): [ka]

[0064] <Synthesis Example 3> To 164.47 g of PGME, 35.00 g of EPPN-501H (manufactured by Nippon Kayaku Co., Ltd.), 34.25 g of 2-hexyldecanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1.24 g of ethyltriphenylphosphonium bromide as a catalyst were added, and the mixture was reacted at 140°C for 24 hours to obtain a solution containing the reaction product. An anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachi Technos Co., Ltd.) was added. 50 g of the filtrate and 70.50 g of a cation exchange resin (product name: Amberlyst [registered trademark] 15JWET, Organo Corporation) were added, and the mixture was stirred at 25 to 30°C for 4 hours and then filtered. GPC analysis of the resulting reaction product revealed that the weight average molecular weight, calculated in terms of standard polystyrene, was 2,200. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (C): [ka]

[0065] <Synthesis Example 4> To 86.52 g of PGME, 15.00 g of EPICLON HP-4700 (manufactured by DIC Corporation), 9.32 g of 9-anthracenecarboxylic acid, 11.99 g of 4-(heptyloxy)benzoic acid (manufactured by Sanuki Chemical Industry Co., Ltd.), and 0.86 g of ethyltriphenylphosphonium bromide as a catalyst were added, and the mixture was reacted at 140°C for 24 hours to obtain a solution containing the reaction product. 37.08 g of anion exchange resin (product name: AMBERJET® ESG4002(OH), Organo Corporation) and 37.08 g of cation exchange resin (product name: AMBERLYST® 15JWET, Organo Corporation) were added, and the mixture was stirred at 25 to 30°C for 4 hours and then filtered. GPC analysis of the resulting reaction product revealed that the weight average molecular weight, calculated in terms of standard polystyrene, was 1,600. The resulting reaction product is presumed to be a copolymer having a structural unit represented by the following formula (D): [ka]

[0066] [Preparation of Resist Underlayer Film-Forming Composition] Example 1 66.31 g of a solution containing 16.97 g of the copolymer obtained in Synthesis Example 1 (solvent: PGME used in synthesis, solids content: 25.59 wt%) was mixed with 4.24 g of tetramethoxymethylglycoluril (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 12.73 g of a 1 wt% PGME solution of pyridinium p-toluenesulfonate, 265.45 g of PGME, and 1.27 g of a 1 wt% PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 6.10 wt% 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.

[0067] <Comparative Example 1> 19.52 g of a solution containing 4.51 g of the copolymer obtained in Synthesis Example 2 (solvent: the PGME / PGMEA mixed solvent used in the synthesis, solids content: 23.26% by 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% by mass PGME solution of pyridinium p-toluenesulfonate, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30) to obtain a 6.35% 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.

[0068] <Comparative Example 2> 74.02 g of a solution containing 19.48 g of the copolymer obtained in Synthesis Example 3 (solvent: PGME used in synthesis, solids content: 26.30 wt%) was mixed with 4.87 g of tetramethoxymethylglycoluril (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 14.60 g of a 1 wt% PGME solution of pyridinium p-toluenesulfonate, 156.91 g of PGME, 97.65 g of PGMEA, and 1.95 g of a 1 wt% PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 7.00 wt% 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.

[0069] <Comparative Example 3> 12.65 g of a solution containing 3.58 g of the copolymer obtained in Synthesis Example 4 (solvent: PGME used in synthesis, solids content: 28.27% by mass) was mixed with 0.89 g of tetramethoxymethylglycoluril (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Cytec Industries Co., Ltd.), 2.68 g of a 1% by mass PGME solution of pyridinium p-toluenesulfonate, 33.50 g of PGME, and 0.27 g of a 1% by mass PGME solution of a surfactant (manufactured by DIC Corporation, product name: R-30N) to obtain a 6.21% 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.

[0070] [Photoresist solvent elution test] The resist underlayer film-forming compositions prepared in Example 1 and Comparative Examples 1 to 3 were each applied onto a silicon wafer using a spinner. They were then baked on a hot plate for 1 minute at the temperature shown in Table 1 below to form resist underlayer films (film thickness: 0.2 μm). These resist underlayer films were immersed in a PGME / PGMEA mixed solvent (mixing ratio: PGME / PGMEA 70 / 30), which is a solvent used in photoresist solutions, to confirm that they were insoluble in the solvent. The results are indicated by "○" in Table 1 below.

[0071] [Optical parameter testing] The resist underlayer film-forming compositions prepared in Example 1 and Comparative Examples 1 to 3 were applied onto silicon wafers using a spinner. They were then baked on a hot plate for 1 minute at the temperatures shown in Table 1 below to form resist underlayer films (film thickness: 0.2 μm). These resist underlayer films were then measured using an optical ellipsometer (JA Woollam, VUV-VASE) The refractive index (n value) and extinction coefficient (k value) at a wavelength of 193 nm were measured using a spectrophotometer (VU-302). The results are shown in Table 1 below. In order for the resist underlayer film to have sufficient anti-reflection function, the k value at a wavelength of 193 nm is preferably 0.1 or more and 0.5 or less.

[0072] [Table 1]

[0073] [Coating test on uneven substrate] To evaluate planarization, a comparison was made between the coating thickness of a trench pattern area (TRENCH) with a trench width of 10 nm and a pitch of 100 nm and an iso-trench pattern area (ISO) with a trench width of 100 nm and a pitch of 10 μm on a 100-nm-thick SiO2 substrate. The resist underlayer film-forming compositions of Example 1 and Comparative Examples 1 to 3 were applied to the substrate in a thickness of 240 nm and then baked on a hot plate for 1 minute at the temperature shown in Table 1 to form a resist underlayer film (thickness: 0.24 μm). 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 trench area (patterned area) and the iso-area (non-patterned area) of the stepped substrate (the coating step between the trench area and the iso-area, referred to as 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.

[0074] [Table 2] When comparing the planarization properties, the result of Example 1 showed a smaller coating step between the pattern area and the open area than the results of Comparative Examples 1 to 3, and therefore it can be said that the resist underlayer film obtained from the resist underlayer film-forming composition of Example 1 had good planarization properties. Furthermore, the resist underlayer film-forming composition of Example 1 has good storage stability, and the resist underlayer film obtained from this composition exhibits good etching resistance and good heat resistance of the film during baking. Another advantage is that the amount of sublimation during baking is small. [Industrial Applicability]

[0075] The resist underlayer film-forming composition of the present invention can be applied to a substrate, even on a substrate having unevenness, to form a flat film. Furthermore, since the composition has an appropriate antireflection effect, it is useful as a resist underlayer film-forming composition.

Claims

1. A resist underlayer film-forming composition comprising a compound represented by the following formula (1) and a solvent: 【Chemistry 1】 (In the formula, Ar １ , Ar ２ , Ar ３ , Ar ４ each independently represents an optionally substituted monovalent aromatic hydrocarbon group, a, b, c, and d each represent 0 or 1, and a+b+c+d=1.

2. 2. The resist underlayer film forming composition according to claim 1, wherein the aromatic hydrocarbon group is a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, or a combination thereof.

3. 3. The resist underlayer film forming composition according to claim 1, wherein the aromatic hydrocarbon group is unsubstituted.

4. 3. The resist underlayer film forming composition according to claim 1, wherein the aromatic hydrocarbon group is an aromatic hydrocarbon group bonded to an alkyl substituent with or without oxygen, as represented by the following formula (2): 【Chemistry 2】 (Ar represents an aromatic hydrocarbon group, n is 0 or 1, and R is an alkyl group having 1 to 19 carbon atoms.)

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

6. 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 5.

7. 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 5; 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 using the formed resist pattern; and A process for processing a semiconductor substrate using a patterned resist underlayer film. A method for manufacturing a semiconductor device comprising:

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