Resist underlayer film-forming composition

Abstract

To provide a resist underlayer-forming composition having dry etching resistance to a fluorocarbon-containing gas comparable to that of fullerene derivatives and further having excellent film hardness even when easily available cheep materials are used, and a production method of the same.SOLUTION: A resist underlayer, formed by using a resist underlayer-forming composition comprising a polymer of a 6-60C aromatic compound having at least one or more structures in which a formyl group and a hydroxy group are respectively bonded to two mutually adjacent carbons and a solvent, has high etching resistance close to a material using fullerene and a low film contraction coefficient and easily maintains in-surface uniformity of the underlayer, and thereby can suppress occurrence of any non-photosensitive region. In addition, the resist underlayer exhibits high hardness and therefore is advantageous to substrate processing with etching.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resist underlayer film-forming composition for forming a resist underlayer film used in a lithography process, and a method for producing the same. [Background technology]

[0002] In the lithography process for manufacturing semiconductor devices, a technique for forming a resist pattern of a desired shape by providing a resist underlayer film prior to forming a photoresist film is known. Patent Document 1 below describes a resist underlayer film-forming composition prepared using a fullerene derivative. Fullerene derivatives are compounds with a high carbon content, and have high hardness when formed into a resist underlayer film. In addition, when forming a resist underlayer film from the resist underlayer film-forming composition, they have high dry etching resistance against fluorocarbon-containing gases, and have therefore been used as useful materials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 143436 Summary of the Invention [Problem to be solved by the invention]

[0004] However, fullerene derivatives have a special chemical structure and are therefore not readily available. In addition, they are expensive, so they are not necessarily useful materials for industrial use. An object of the present invention is to provide a composition for forming a resist underlayer film that has dry etching resistance against a fluorocarbon-containing gas at the same level as fullerene derivatives, even when using readily available and inexpensive materials, and that also has excellent film hardness, and a method for producing the same. [Means for solving the problem]

[0005] As a result of extensive investigations, the inventors have found a composition for forming a resist underlayer film having high dry etching resistance and excellent film hardness, and have completed the present invention. That is, the present invention includes the following. 1. A resist underlayer film-forming composition comprising a polymer of an aromatic compound having 6 to 60 carbon atoms and having at least one structure in which a formyl group and a hydroxy group are bonded to two adjacent carbon atoms, and a solvent. 2. The resist underlayer film-forming composition according to the above item 1, wherein the aromatic compound is a compound represented by formula (1). [ka] (In formula (1), Ar1 represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, or an aromatic ring having 6 to 59 carbon atoms which may be substituted with a halogen atom, a hydroxy group, an ether group, or an alkoxy group.) 3. The resist underlayer film according to 2 above, wherein in formula (1), Ar1 is a monocyclic ring, a fused ring, a heterocyclic ring, or a linked ring in which these rings are linked by a single bond or via a spacer. The present invention relates to a forming composition. 4. The resist underlayer film forming composition according to the above item 2, wherein in formula (1), Ar1 is any one of a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring. 5. The resist underlayer film-forming composition according to any one of items 1 to 4 above, further comprising a crosslinking agent. 6. The resist underlayer film-forming composition according to any one of items 1 to 5 above, further comprising an acid and / or an acid generator. 7. The resist underlayer film forming composition according to any one of items 1 to 6 above, wherein the boiling point of the solvent is 160° C. or higher. 8. A resist underlayer film, which is a fired product of a coating film made of the resist underlayer film-forming composition according to any one of 1 to 7 above. 9. A method for producing a resist underlayer film, comprising baking a resist underlayer film-forming composition according to any one of 1 to 8 above that has been applied onto a semiconductor substrate. 10. The method for producing a resist underlayer film according to the above item 9, wherein the baking is carried out in two stages. 11. The method for producing a resist underlayer film according to the above item 10, wherein the baking temperature in the second stage of the baking is 400° C. or higher. 12. The method for producing a resist underlayer film according to any one of items 9 to 11 above, wherein the baking is carried out in an inert gas atmosphere. 13. A step of forming a resist underlayer film on a semiconductor substrate using the resist underlayer film-forming composition described in any one of 1 to 8 above; 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 of processing a semiconductor substrate through 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]

[0006] The resist underlayer film formed using the resist underlayer film-forming composition of the present invention has high etching resistance similar to that of materials using fullerene, a low film shrinkage rate, and easy maintenance of inner surface uniformity of the underlayer film, thereby suppressing the occurrence of non-photosensitive regions. In addition, the resist underlayer film exhibits high hardness, which is advantageous for substrate processing by etching. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention provides a resist underlayer film-forming composition containing a polymer of an aromatic compound having 6 to 60 carbon atoms and having at least one structure in which a formyl group and a hydroxy group are bonded to two adjacent carbon atoms, and a solvent.

[0008] [Aromatic compounds with 6 to 60 carbon atoms] The aromatic compound having 6 to 60 carbon atoms is a compound represented by formula (1). [ka] (In formula (1), Ar1 represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, or an aromatic ring having 6 to 59 carbon atoms which may be substituted with a halogen atom, a hydroxy group, an ether group, or an alkoxy group.)

[0009] [Aromatic rings with 6 to 59 carbon atoms (Ar1)] The aromatic ring (Ar1) having 6 to 59 carbon atoms is a monocyclic ring, a fused ring, a heterocyclic ring, or a linked ring in which these rings are linked by a single bond or via a spacer. Specifically, the aromatic ring (Ar1) having 6 to 59 carbon atoms is (a) may be a single ring such as benzene or phenol, (b) may be a fused ring such as naphthalene, anthracene, pyrene, hydroxynaphthalene, naphthol, 9,10-anthraquinone, or indenofluorenedione; (c) may be a heterocycle such as furan, thiophene, pyridine, carbazole, phenothiazine, phenoxazine, or indolocarbazole; (d) A ring in which the aromatic rings of (a) to (c) are bonded together by a single bond, such as biphenyl, phenylindole, 9,9-bis(4-hydroxyphenyl)fluorene, α,α,α',α'-tetrakis(4-hydroxyphenyl)-p-xylene, or 9,9-fluorenylidene-bisnaphthol, The aromatic rings (a) to (d) may be linked via a spacer, such as (e) phenylnaphthylamine, where the substituent R can be exemplified by an alkyl group having 1 to 20 carbon atoms, as described below. An example of a spacer is -(CH2) nExamples thereof include one or a combination of two or more of -(n=1 to 20), -CH=CH-, -C≡C-, -N=N-, -NH-, -NR-, -NHCO-, -NRCO-, -S-, -COO-, -OCO-, -O-, -CO-, -Ph-, -Ph-Ph-, -Ph-O-Ph-(Ph=C6H4), and -CH=N-. Two or more of these spacers may be linked together.

[0010] In addition to the aromatic rings exemplified above, Ar1 further includes pyrimidine, pyrazine, pyrrole, oxazole, thiazole, imidazole, quinoline, fluorene, quinazoline, purine, indolizine, benzothiophene, benzofuran, indole, acridine, and the like.

[0011] The hydrogen atoms of the aromatic ring (Ar1) having 6 to 59 carbon atoms may be substituted with an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a halogen atom, a hydroxy group, an ether group, or an alkoxy group.

[0012] The alkyl group having 1 to 20 carbon atoms includes a linear or branched alkyl group 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 even more preferably an alkyl group having 1 to 4 carbon atoms.

[0013] Examples of the alkenyl group having 2 to 10 carbon atoms and the alkynyl group having 2 to 10 carbon atoms include linear or branched alkenyl groups and alkynyl groups which may or may not have a substituent, such as a vinyl group, an ethynyl group, a 2-propenyl group, a 2-propynyl group, a 2-butenyl group, a 2-butynyl group, a 3-butenyl group, and a 3-butynyl group.

[0014] Examples of the substituents of the alkyl group having 1 to 20 carbon atoms which may have a substituent, the alkenyl group having 2 to 10 carbon atoms which may have a substituent, and the alkynyl group having 2 to 10 carbon atoms which may have a substituent include a formyl group, a halogen atom, a hydroxy group, an ether group, and an alkoxy group.

[0015] The aromatic ring (Ar1) is preferably a benzene ring, a naphthalene ring, an anthracene ring, or a pyrene ring. The aromatic ring (Ar1) may be a condensed ring in which two or more types of aromatic rings (Ar1) are condensed together, as long as the number of carbon atoms does not exceed 59.

[0016] [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.

[0017] 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 Cholesterol 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 dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene ethylene 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-3-methoxybutylpropionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, , 4-methyl-2-pentanol, and γ-butyrolactone, etc. These solvents can be used alone or in combination of two or more.

[0018] In addition, the following compounds described in WO2018 / 131562A1 can also be used. [ka] (R4, R5, and R6 in formula (i) each represent 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 from one another and may be bonded to one another to form a ring structure.)

[0019] 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 even more preferably an alkyl group having 1 to 4 carbon atoms.

[0020] Examples of alkyl groups 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 alkyl groups having 1 to 20 carbon atoms interrupted by -O-, -S-, -NHCO-, or -CONH- units include methoxy, ethoxy, propoxy, butoxy, methylthio, ethylthio, propylthio, butylthio, methylcarbonylamino, ethylcarbonylamino, propylcarbonylamino, butylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, propylaminocarbonyl, butyl ... 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.

[0021] 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.

[0022] Specific examples of preferred compounds represented by formula (i) are shown below. [ka]

[0023] Among the above, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and the compound of the following formula: [ka] Compounds represented by the formula (i) are preferably 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutyramide.

[0024] 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). Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutyramide are particularly preferred.

[0025] [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.

[0026] 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.

[0027] 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 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. n3 is an integer of 1 to 4, n4 is an integer of 1 to (5-n3), and (n3+n4) is an integer of 2 to 5. n5 is an integer of 1 to 4, n6 is an integer of 0 to (4-n5), and (n5+n6) is an integer of 1 to 4. Oligomers and polymers having a repeating unit structure of 2 to 100 or 2 to 50 can be used.

[0028] Examples of the compounds, polymers and oligomers of formula (4) and formula (5) are shown below. [ka] [ka]

[0029] 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 solids 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.

[0030] [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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0035] 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.

[0036] 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 solids content of the resist underlayer film-forming composition.

[0037] [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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] [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.

[0046] 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 a coater, and then baked to form a resist underlayer film. Baking conditions include a baking temperature of 80°C to The baking temperature is appropriately selected from the following: 800°C, and a baking time of 0.3 to 60 minutes. The baking atmosphere may be air, or an inert gas such as nitrogen or argon. Preferably, pre-baking is performed in air at a baking temperature of 150°C to 350°C for a baking time of 0.5 to 2 minutes, followed by main baking in an inert gas at a baking temperature of 400°C to 800°C, more preferably 450°C to 700°C, and even more preferably 500°C to 600°C, for a baking time of 0.5 to 2 minutes. The oxygen concentration in the inert gas is less than 1% by volume, preferably 0.1% by volume or less, more preferably 0.01% by volume or less, even more preferably 0.005% by volume or less, and particularly preferably 0.003% by volume or less. If the oxygen concentration is high during heating, oxidative decomposition of the resist underlayer film may proceed, potentially preventing the resist underlayer film from exhibiting the required properties. Here, the thickness of the formed underlayer film is, for example, 10 to 1000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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).

[0051] Next, a resist pattern is formed by irradiation with light or electron beams and development. First, exposure is carried out through a predetermined mask. Near ultraviolet, far ultraviolet, or extreme ultraviolet (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 Laser (wavelength 193 nm) and EUV (wavelength 13.5 nm) are preferred. After exposure, post-exposure baking can be performed as needed. The post-exposure baking 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.

[0052] In addition, 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 of such resists 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 manner as when using a photoresist using an electron beam as the irradiation source.

[0053] 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 developing solutions 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 developing solutions. Development conditions are appropriately selected from a temperature of 5°C to 50°C and a time of 10 to 600 seconds.

[0054] 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.

[0055] 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).

[0056] 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.

[0057] 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).

[0058] Furthermore, an organic antireflective coating can be formed on the resist underlayer coating before the formation of the photoresist. The antireflective coating composition used therein is not particularly limited, and any one can be selected from those conventionally used in lithography processes. The antireflective coating can be formed by a conventional method, such as coating with a spinner or coater and baking.

[0059] 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.

[0060] 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.

[0061] 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]

[0062] The weight-average molecular weights shown in the synthesis examples below are the results of measurements by gel permeation chromatography (hereinafter abbreviated as GPC in this specification). Measurements were performed using a GPC apparatus (HLC-8320GPC) manufactured by Tosoh Corporation under the following conditions: GPC columns: TSKgel SuperH-RC, TSKgel SuperMultipore HZ-N, TSKgel SuperMultipore HZ-N (Tosoh Corporation) Column temperature: 40℃ Solvent: Tetrahydrofuran (Kanto Chemical, for high performance liquid chromatography) Standard sample: Polystyrene (Shodex)

[0063] The abbreviations used in the synthesis examples below have the following meanings. PGMEA: Propylene glycol monomethyl ether acetate PGME: Propylene glycol monomethyl ether

[0064] <Synthesis Example 1> (Synthesis of Polymer (1)) [ka] Under nitrogen, a 300 mL four-neck flask was charged with 70.00 g (406.6 mmol) of 2-hydroxy-1-naphthaldehyde (Tokyo Chemical Industry Co., Ltd.), 39.1 g (406.6 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 49.1 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Grade 1), and 114.5 g of PGMEA. The mixture was heated to 150 °C and stirred at 150 °C for 18 hours. The resulting reaction mixture was added dropwise to 1600 mL of a 5 / 5 mixture of methanol (Kanto Chemical, special grade) and water to precipitate the polymer. The resulting precipitate was filtered, dried under vacuum, and then redissolved in cyclohexanone to a solids content of 30%. The polymer was then reprecipitated by adding dropwise to 800 mL of a 5 / 5 mixture of methanol (Kanto Chemical, special grade). The resulting precipitate was filtered and dried under vacuum to obtain the polymer. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to be 524 weight average molecular weight (Mw) with a yield of 30.1%. The resulting polymer was diluted with cyclohexanone to a solids concentration of 30%, and cation exchange resin and anion exchange resin in amounts equal to the solids were added and stirred for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0065] <Synthesis Example 2> (Synthesis of Polymer (2)) [ka] Under nitrogen, 8.00 g (65.5 mmol) of salicylaldehyde (Tokyo Chemical Industry Co., Ltd.), 6.3 g (65.5 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 6.4 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Grade 1), and 15.0 g of PGMEA were placed in a 100 mL two-neck flask and heated to 150°C. The mixture was stirred at 150°C for 18 hours. The resulting reaction mixture was diluted with 350 mL of methanol (Kanto Chemical, Special Grade) / water (5 / 5). The polymer was precipitated by dropping it into the mixed solvent. The resulting precipitate was filtered off and dried in vacuum to obtain a polymer. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 3,200. The resulting polymer was diluted with cyclohexanone to a solids concentration of 30%, and cation exchange resin and anion exchange resin in amounts equal to the solids were added, followed by stirring for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0066] <Synthesis Example 3> (Synthesis of Polymer (3)) [ka] Under nitrogen, a 100 mL two-neck flask was charged with 8.00 g (58.8 mmol) of 3-methylsalicylaldehyde (Tokyo Chemical Industry Co., Ltd.), 5.6 g (58.8 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 6.1 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Grade 1), and 14.3 g of PGMEA. The mixture was heated to 150 °C and stirred at 150 °C for 18 hours. The resulting reaction mixture was added dropwise to 350 mL of a 5:5 mixture of methanol (Kanto Chemical, Special Grade) and water to precipitate the polymer. The resulting precipitate was filtered and dried under vacuum to obtain the polymer. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to have a weight-average molecular weight (Mw) of 1,000. The resulting polymer was diluted with PGME to a solids concentration of 30%, and then cation exchange resin and anion exchange resin in amounts equal to the solids were added and stirred for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0067] <Synthesis Example 4> (Synthesis of Polymer (4)) [ka] Under nitrogen, 8.00 g (58.8 mmol) of 4-methylsalicylaldehyde (Tokyo Chemical Industry Co., Ltd.), 5.6 g (58.8 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 6.1 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Grade 1) and 14.3 g of PGMEA were placed in a 100 mL two-neck flask and heated to 150°C. The mixture was stirred at 150°C for 18 hours. The resulting reaction mixture was diluted with 350 mL of methanol (Kanto Chemical, Special Grade) / water. The polymer was precipitated by dropping it into a (5 / 5) mixed solvent. The resulting precipitate was filtered off and dried in a vacuum to obtain a polymer. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent), and the weight average molecular weight (Mw) was found to be 1500. The resulting polymer was diluted with PGME to a solids concentration of 30%, and cation exchange resin and anion exchange resin in amounts equal to the solids were added, followed by stirring for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0068] <Synthesis Example 5> (Synthesis of Polymer (5)) [ka] Under nitrogen, a 100 mL two-neck flask was charged with 8.00 g (58.8 mmol) of 5-methylsalicylaldehyde (Tokyo Chemical Industry Co., Ltd.), 5.6 g (58.8 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 6.1 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Grade 1), and 14.3 g of PGMEA. The mixture was heated to 150 °C and stirred at 150 °C for 18 hours. The resulting reaction mixture was added dropwise to 350 mL of a 5:5 mixture of methanol (Kanto Chemical, Special Grade) and water to precipitate the polymer. The resulting precipitate was filtered and dried under vacuum to obtain the polymer. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to be 800 weight average molecular weight (Mw). The resulting polymer was diluted with PGME to a solids concentration of 30%, and then cation exchange resin and anion exchange resin in amounts equal to the solids were added and stirred for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0069] Comparative Synthesis Example 1 (Synthesis of Polymer (7)) [ka] Under nitrogen, 25.00 g of 2,2'-biphenol (Tokyo Chemical Industry Co., Ltd.), 10.5 g of 1-naphthaldehyde (Tokyo Chemical Industry Co., Ltd.), 15.5 g of 1-pyrenecarboxaldehyde (Aldrich), and 3.87 g of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.) were placed in a 100 mL two-neck flask. The mixture was then heated to 120 °C and cooled to room temperature after approximately 24 hours. The mixture was precipitated with methanol and the resulting precipitate was dried. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 2,000. The resulting polymer was diluted with PGMEA to a solids concentration of 30%, and cation exchange resin and anion exchange resin in amounts equal to the solids were added. The mixture was stirred for 4 hours. The ion exchange resin was filtered to obtain a polymer solution.

[0070] Comparative Synthesis Example 2 (Synthesis of Polymer (8)) [ka] Under nitrogen, 9.80 g of di-tert-butyl malonate (manufactured by Aldrich) was placed in a 3-liter four-neck flask, and 150 cm of 1,2,4-trimethylbenzene was added. 3 6.50 g of diazabicyclo[5.4.0]undec-7-ene (1,8-diazabicyclo[5.4.0]undec-7-ene, manufactured by Tokyo Chemical Industry Co., Ltd.) was added and the temperature was adjusted to 4°C while stirring. 10.9 g of iodine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the reaction solution obtained after temperature adjustment at 130 cm 3 A dark purple solution of 1,2,4-trimethylbenzene containing 5.00 g of fullerene mixture (containing C60, C70 and other higher fullerenes, manufactured by Frontier Carbon Corporation) was slowly added dropwise to the reaction solution in the reaction vessel. The temperature inside the flask was controlled to 11°C during the addition using an ice bath. After the addition was completed, the temperature of the reaction solution was returned to room temperature, and then 5.00 g of a fullerene mixture (containing C60, C70 and other higher fullerenes, manufactured by Frontier Carbon Corporation) was added to the reaction solution in the reaction vessel in a solution of 350 cm of 1,2,4-trimethylbenzene. 3A solution of 1,8-diazabicyclo[5.4.0]undec-7-ene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the reaction solution in the flask with stirring. 3 A solution diluted with 1,2,4-trimethylbenzene was slowly added dropwise with stirring. The mixture was stirred at room temperature for 6.5 hours to react. The reaction layer (organic phase) of the resulting reaction solution was washed four times with a saturated aqueous solution of sodium sulfite. The resulting organic phase was then washed with 100 cm of a 1N aqueous solution of sulfuric acid. 3 After washing twice with 200 cm 3 The solid was washed three times with 1,2,4-trimethylbenzene. The solvent (1,2,4-trimethylbenzene) was distilled off under reduced pressure to obtain 9.50 g of a reddish-brown solid. The obtained solid was fractionated by silica gel chromatography using a mixed solvent of n-hexane and ethyl acetate to obtain a fullerene derivative (malonic acid-di-tert-butyl ester adduct).

[0071] Comparative Synthesis Example 3 (Synthesis of Polymer (9)) [ka] Under nitrogen, 12.5 g (76.5 mmol) of 1,5-dihydroxynaphthalene (Tokyo Chemical Industry Co., Ltd.), 3.55 g (2.1 mmol) of paratoluenesulfonic acid monohydrate (Tokyo Chemical Industry Co., Ltd.), and 74.4 g of PGME were placed in a 300 mL four-neck flask and heated to 85 °C. 5.86 g of 37% formaldehyde solution (Tokyo Chemical Industry Co., Ltd.) was added dropwise to the reaction solution. After approximately 5 hours, the mixture was allowed to cool to room temperature, precipitated with heptane, and the resulting precipitate was dried. The weight-average molecular weight (Mw) measured by GPC in terms of polystyrene was 1,400.

[0072] Comparative Synthesis Example 4 (Synthesis of Polymer (10)) [ka] Under nitrogen, 4.00 g (23.2 mmol) of 6-hydroxy-1-naphthaldehyde (Tokyo Chemical Industry Co., Ltd.), 2.23 g (23.2 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), 7.41 g of N-methyl-2-pyrrolidinone (Kanto Chemical, Shika Grade 1), and 17.4 g of PGMEA were placed in a 100 mL two-neck flask and heated to 150°C, resulting in a gel within approximately 1 hour.

[0073] Example 1 0.14 g of PGMEA containing 1% surfactant (manufactured by DIC Corporation, product name: Megafac [product name] R-40, fluorine-based surfactant), 2.40 g of PGMEA, and 2.13 g of cyclohexanone were mixed with 5.31 g of the resin solution obtained in Synthesis Example 1. The mixture was then filtered through a polytetrafluoroethylene microfilter with a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0074] <Example 2> 0.10 g of PGMEA containing 1% surfactant (manufactured by DIC Corporation, product name: Megafac [product name] R-40, fluorine-based surfactant), 1.80 g of PGME, 3.50 g of PGMEA, and 0.61 g of cyclohexanone were mixed with 3.98 g of the resin solution obtained in Synthesis Example 2. The mixture was then filtered through a polytetrafluoroethylene microfilter with a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0075] Example 3 0.21 g of PGMEA containing 1% surfactant (manufactured by DIC Corporation, product name: Megafac [product name] R-40, fluorine-based surfactant), 0.53 g of PGME, and 3.66 g of PGMEA were mixed with 10.59 g of the resin solution obtained in Synthesis Example 3. The mixture was then filtered through a polytetrafluoroethylene microfilter with a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0076] Example 4 0.21 g of PGMEA containing 1% surfactant (manufactured by DIC Corporation, product name: Megafac [product name] R-40, fluorine-based surfactant), 2.34 g of PGME, and 3.66 g of PGMEA were mixed with 8.78 g of the resin solution obtained in Synthesis Example 4. The mixture was then filtered through a polytetrafluoroethylene microfilter with a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0077] <Example 5> 9.79 g of the resin solution obtained in Synthesis Example 5 was mixed with 1% surfactant (manufactured by DIC Corporation, product name: Mega 0.21 g of PGMEA containing FACT (trade name R-40, a fluorosurfactant), 1.32 g of PGME, and 3.66 g of PGMEA were mixed together, and the mixture was then filtered through a polytetrafluoroethylene microfilter with a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0078] Example 6 7.82 g of the resin obtained in Synthesis Example 1 was mixed with 2.54 g of PGME containing 2% pyridinium p-hydroxybenzenesulfonate, 0.51 g of TMOM-BP (a crosslinking agent manufactured by Honshu Chemical Industry Co., Ltd.), 0.20 g of PGMEA containing 1% of a surfactant (a fluorine-based surfactant manufactured by DIC Corporation, product name: Megafac [product name] R-40), 4.35 g of PGME, 4.15 g of PGMEA, and 0.42 g of cyclohexanone. The mixture was then filtered through a 0.1 μm diameter polytetrafluoroethylene microfilter to prepare a solution of a resist underlayer film-forming composition.

[0079] <Comparative Example 1> The resin solution (solid content: 29.9% by mass) was obtained in Comparative Synthesis Example 1. 0.10 g of PGMEA containing 1% by mass of a surfactant (MEGAFACE R-40, manufactured by DIC Corporation), 3.68 g of PGMEA, and 2.68 g of PGME were added to and dissolved in 3.02 g of this resin solution, and the mixture was filtered through a polytetrafluoroethylene microfilter having a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0080] <Comparative Example 2> 1.0 g of the fullerene derivative obtained in Comparative Synthesis Example 2 was mixed with 0.15 g of an epoxy compound represented by the following formula (6) (manufactured by Tohto Kasei Co., Ltd., product name: YH434L) and 0.001 g of Megafac (registered trademark) R-30 (DIC Corporation) as a surfactant, and dissolved in 7.0 g of PGMEA to form a solution. The mixture was then filtered using a polyethylene microfilter with a pore size of 0.10 μm, and further filtered using a polyethylene microfilter with a pore size of 0.05 μm to prepare a resist underlayer film-forming composition solution. [ka]

[0081] <Comparative Example 3> 0.25 g of PGMEA containing 1 mass % of a surfactant (MEGAFAC R-40, manufactured by DIC Corporation), 6.09 g of PGME, and 2.35 g of PGMEA were added to 1.29 g of the resin obtained in Comparative Synthesis Example 3 and dissolved, and the mixture was filtered through a polytetrafluoroethylene microfilter having a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0082] [Measurement of film shrinkage rate] Each of the resist underlayer film-forming compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 was applied to a silicon wafer using a spinner. The wafer was then baked on a hot plate in the atmosphere at 350°C for 1 minute to form a resist underlayer film (thickness: approximately 0.25 μm), and the film thickness A was measured. The substrate was further baked in a nitrogen atmosphere at 500°C or 600°C for 5 minutes, and the film thickness B was measured. The value obtained by dividing film thickness B by film thickness A x 100 was defined as the film shrinkage rate. In addition, when the firing temperature is 500°C, it is written as "Code-1" in Table 1, and when the firing temperature is 600 In the case of °C, it is written as "Symbol-2" in Table 1. The film shrinkage rate of the resist underlayer film composition prepared in Comparative Example 1 was as high as 50%, whereas the compositions of Examples 1 to 6 had a low rate of 25% or less. This has the advantage of reducing the amount of sublimate and thus the contamination of the device, and a low shrinkage rate is also advantageous for the in-plane uniformity of the film.

[0083] [Measurement of Dry Etching Rate] The resist underlayer film-forming compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were each applied onto a silicon wafer using a spinner. The wafer was then baked on a hot plate at 350°C for 1 minute, and then baked in a nitrogen atmosphere at 500°C and 600°C for 5 minutes to form a resist underlayer film (film thickness: 0.2 μm). The dry etching rates of these resist underlayer films were measured using a Samco Inc. RIE system under conditions in which CF4 was used as the dry etching gas. The dry etching rate (ER) of each resist underlayer film was calculated when the dry etching rate (ER) of Comparative Example 2-1 (fullerene) was set to 1.00. The results are shown in Table 1 below as "relative dry etching rate." The resist underlayer film formed in Comparative Example 2-1 has a dry etching rate that can replace an amorphous carbon layer formed by vapor deposition. On the other hand, the resist underlayer films formed in Examples 1 to 6 have high etching resistance close to that of the material using fullerene (Comparative Example 2).

[0084] [Measurement of hardness] Using the resist underlayer film-forming compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3, resist underlayer films were formed on silicon wafers by the same method as above. A nanoindentation test was performed using a nanoindenter manufactured by Toyo Corporation to measure the hardness of the resist underlayer films. Examples 1 to 6 exhibited hardness of 1.40 GPa or more, demonstrating that they have a denser structure and are therefore advantageous for substrate processing by etching.

[0085] [Table 1]

Claims

1. A resist underlayer film-forming composition comprising a polymer consisting solely of an aromatic compound represented by formula (1) and having a weight average molecular weight of 524 or more and 3,200 or less, and a solvent. 【Chemical 1】 (In formula (1), Ar １ represents an aromatic ring having 6 to 59 carbon atoms which may be substituted with an alkyl group having 1 to 20 carbon atoms, a halogen atom, a hydroxy group or an alkoxy group.

2. In formula (1), Ar １ 2. The resist underlayer film forming composition according to claim 1, wherein is a monocyclic ring, a fused ring, a heterocyclic ring, or a linked ring in which these rings are linked by a single bond.

3. In formula (1), Ar １ 2. The resist underlayer film forming composition according to claim 1, wherein is any one of a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring.

4. The resist underlayer film-forming composition according to claim 1 , further comprising a crosslinking agent.

5. The resist underlayer film forming composition according to claim 1 , further comprising an acid and / or an acid generator.

6. 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 method for producing a resist underlayer film, comprising baking the resist underlayer film-forming composition according to claim 1 applied onto a semiconductor substrate to form a resist underlayer film.

9. 9. The method for producing a resist underlayer film according to claim 8, wherein the baking is carried out in two stages.

10. 10. The method for producing a resist underlayer film according to claim 9, wherein the baking temperature in the second stage of the baking is 400[deg.] C. or higher.

11. The method for producing a resist underlayer film according to any one of claims 8 to 10, wherein the baking is carried out in an inert gas atmosphere.

12. 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 of processing a semiconductor substrate through a patterned resist underlayer film A method for manufacturing a semiconductor device comprising:

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