Composition for resist underlayer film formation

Abstract

This invention provides a resist underlayer film forming composition exhibiting high etch resistance, good dry etch rate ratio and optical constants, good coverage of substrates with varying elevations, small thickness differences after embedding, and the ability to form a planar film. It also provides a resist underlayer film using this resist underlayer film forming composition and a method for manufacturing a semiconductor device. The resist underlayer film forming composition comprises a polymer having a partial structure shown in formula (1) and a solvent. (In the formula, Ar represents an aromatic group having 6 to 20 substituted carbon atoms).

Description

Technical Field

[0001] The present invention relates to a resist underlayer film forming composition exhibiting high etch resistance, good dry etch rate ratio and optical constant, good coverage of so-called high-low difference substrates, small film thickness difference after embedding, and the ability to form a flat film, a resist underlayer film using the resist underlayer film forming composition, and a method for manufacturing a semiconductor device. Background Technology

[0002] In recent years, for the lower layer film material of the resist used in multilayer resist processes, it is required that it function as an anti-reflective film, especially for short-wavelength exposure, and has appropriate optical constants, while also having etch resistance in substrate processing. A polymer with repeating units containing benzene rings has been proposed (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-354554 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] To achieve the miniaturization of resist patterns and the resulting thinning of the resist layer, a photolithography process is known that forms at least two resist underlayers and uses these resist underlayers as mask materials. This process involves depositing at least one organic film (lower organic film) and at least one inorganic underlayer on a semiconductor substrate. The resist pattern formed on the upper resist film is used as a mask to pattern the inorganic underlayer, and this pattern is then used as a mask to pattern the lower organic film. This method can form patterns with high aspect ratios. Examples of materials for forming the at least two layers include combinations of organic resins (e.g., acrylic resins, phenolic varnish resins) and inorganic materials (e.g., silicone resins (e.g., organopolysiloxanes), inorganic silicon compounds (e.g., SiON, SiO2)). Furthermore, in recent years, to obtain a single pattern, a dual patterning technique involving two photolithography and two etching processes has been widely used, employing the aforementioned multilayer process in each step. In this case, the organic film formed after the initial pattern needs to possess the characteristic of planarizing surface differences.

[0008] However, for substrates with varying heights and densities in the resist pattern formed on the substrate being processed, there are also problems such as low coverage of the resist underlayer film forming composition, large film thickness difference after embedding, and difficulty in forming a flat film.

[0009] This invention addresses the problem of forming a photoresist underlayer film by providing a composition exhibiting high etch resistance, a good dry etch rate ratio, and good optical constants. It also demonstrates good coverage even on substrates with significant surface variations, minimal thickness differences after embedding, and the ability to form a flat film. Furthermore, this invention aims to provide a photoresist underlayer film using this composition, and a method for manufacturing a semiconductor device.

[0010] means for solving problems

[0011] This invention includes the following:

[0012] [1] A composition for forming a resist underlayer film, comprising a polymer having a partial structure as shown in formula (1) and a solvent.

[0013]

[0014] (In the formula, Ar represents an aromatic group with 6 to 20 carbon atoms that can be substituted.)

[0015] The composition for forming a lower layer of resist film as described in [2][1], wherein Ar in formula (1) is phenyl, naphthyl, anthraceneyl, pyreneyl, or a combination thereof.

[0016] The composition for forming a resist underlayer film as described in [3][1], wherein Ar in formula (1) is naphthyl, anthraceneyl, or a combination thereof.

[0017] The composition for forming a resist underlayer film as described in any one of [4][1] to [3] further comprises a crosslinking agent.

[0018] The composition for forming a resist underlayer film according to any one of [5][1] to [4] further comprises an acid and / or an acid-generating agent.

[0019] The composition for forming a resist underlayer film as described in [6][1], wherein the solvent has a boiling point of 160°C or higher.

[0020] [7] A resist underlayer film, characterized in that it is a sintered product of a coating film formed by any one of the resist underlayer film forming compositions described in any one of [1] to [6].

[0021] [8] A method for manufacturing a semiconductor device, comprising:

[0022] The process of forming a photoresist underlayer film on a semiconductor substrate using the photoresist underlayer film forming composition according to any one of [1] to [6];

[0023] The process of forming a resist film on the formed resist underlayer film;

[0024] The process of forming a resist pattern by irradiating the formed resist film with light or an electron beam and then developing it;

[0025] The process of etching and patterning the underlying resist film using the formed resist pattern; and

[0026] The process of processing a semiconductor substrate using a patterned resist underlayer film.

[0027] Invention Effects

[0028] The resist underlayer film formation composition of the present invention not only has high etch resistance, good dry etch rate ratio and optical constant, but also the obtained resist underlayer film has good coverage for so-called high-low difference substrates, with small film thickness difference after embedding, forming a flat film, and realizing finer substrate processing.

[0029] In particular, the resist underlayer film formation composition of the present invention is effective for photolithography processes that form at least two resist underlayer films with the aim of thinning the resist film thickness and use the resist underlayer film as an etching mask. Detailed Implementation

[0030] [Composition for forming the underlayer of the resist]

[0031] The composition for forming a resist underlayer film according to the present invention comprises a polymer having a partial structure shown in formula (1), a solvent, and other components.

[0032]

[0033] (In the formula, Ar represents an aromatic group with 6 to 20 carbon atoms that can be substituted). The following will explain in turn.

[0034] [Polymers having a partial structure as shown in formula (1)]

[0035] In the partial structure shown in formula (1), Ar represents an aromatic group with 6 to 20 carbon atoms that can be substituted.

[0036] As aromatic groups with 6 to 20 carbon atoms, examples can be given of groups obtained by removing one hydrogen atom from an aromatic compound that can be substituted.

[0037] Such aromatic compounds can be:

[0038] (a) Monocyclic compounds such as benzene;

[0039] (b) Fused-ring compounds such as naphthalene;

[0040] (c) Heterocyclic compounds such as furan, thiophene, and pyridine;

[0041] (d) Compounds in which aromatic rings of (a) to (c) such as biphenyl are bonded together by single bonds;

[0042] (e) Phenynaphthylamine, which consists of two or more aromatic rings selected from (a) to (d) via -(CH2) n Compounds consisting of one or more spacer groups linked together, including -(n=1~20), -CH=CH-, -C≡C-, -N=N-, -NH-, -NR-, -NHCO-, -NRCO-, -S-, -COO-, -O-, -CO-, and -CH=N-. Furthermore, more than two of these spacer groups may be linked together.

[0043] Specific examples of aromatic compounds include benzene, toluene, xylene, mesitylene, cumene, styrene, indene, naphthalene, azulene, anthracene, phenanthrene, benzo[a]tetraphenylene, triphenylene, pyrene, etc. Thiophene, furan, pyridine, pyrimidine, pyrazine, pyrrole, oxazole, thiazole, imidazole, naphthalene, anthracene, quinoline, carbazole, quinazoline, purine, indazine, benzothiophene, benzofuran, indole, phenylindole, acridine, etc.

[0044] The aromatic groups mentioned above may be substituted by one or more groups selected from the group consisting of halogen atoms, alkyl groups, fused cyclic groups, heterocyclic groups, hydroxyl groups, amino groups, nitro groups, ether groups, alkoxy groups, cyano groups and carboxyl groups having 1 to 20 carbon atoms.

[0045] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0046] Examples of alkyl groups having 1 to 20 carbon atoms include straight-chain or branched alkyl groups, with or without substituents, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, n-octyl, cyclohexyl, 2-ethylhexyl, n-nonyl, isononyl, p-tert-butylcyclohexyl, n-decyl, n-dodecylnonyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, and eicosyl. Examples of cyclic alkyl groups, which may or may not have substituents, include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0047] Preferably, the alkyl group has 1 to 12 carbon atoms; more preferably, it has 1 to 8 carbon atoms; and even more preferably, it has 1 to 4 carbon atoms.

[0048] Alkyl groups having 1 to 20 carbon atoms whose number is interrupted by oxygen, sulfur, or amide bonds can be exemplified by, for example, alkyl groups containing the structural units -CH2-O-, -CH2-S-, -CH2-NHCO-, or -CH2-CONH-. -O-, -S-, -NHCO-, or -CONH- can be one or more units in the aforementioned alkyl groups. Specific examples of alkyl groups with 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, butylaminocarbonyl, etc., and further include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, or octadecyl, and each of them is substituted by methoxy, ethoxy, propoxy, butoxy, methylthio, ethylthio, propylthio, butylthio, methylcarbonylamino, ethylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, etc. Methoxy, ethoxy, methylthio, and ethylthio are preferred, and methoxy and ethoxy are more preferred.

[0049] Fused ring groups refer to substituents derived from fused ring compounds. Specifically, examples include phenyl, naphthyl, anthraceneyl, phenanthrene, tetraphenyl, triphenylene, pyrene, and... The preferred compounds are phenyl, naphthyl, anthraceneyl, and pyrene.

[0050] Heterocyclic groups refer to substituents derived from heterocyclic compounds, specifically thiophene, furanyl, pyridinyl, pyrimidinyl, pyrazinyl, pyrroleyl, oxazolyl, thiazolyl, imidazoleyl, quinolinyl, carbazoleyl, quinazolinyl, purineyl, indazine, benzothiophene, benzofuranyl, indoleyl, acridineyl, isoindoleyl, benzimidazolyl, isoquinolinyl, quinoxalinyl, terpineyl, pteridineyl, chromenyl (benzopyranyl), isochryneyl (benzopyranyl), and isochryneyl (benzopyranyl). (and pyranyl), xanthanyl, thiazolyl, pyrazolyl, imidazolinyl, azazinyl, preferably thienyl, furanyl, pyridyl, pyrimidinyl, pyrazinyl, pyrroleyl, oxazolyl, thiazolyl, imidazolyl, quinolinyl, carbazoleyl, quinazolinyl, purineyl, inzazinyl, benzothienyl, benzofuranyl, indoleyl and azazinyl, most preferably thienyl, furanyl, pyridyl, pyrimidinyl, pyrroleyl, oxazolyl, thiazolyl, imidazolyl and carbazoleyl.

[0051] Ar is preferably phenyl, naphthyl, anthraceneyl or pyrene, more preferably naphthyl or anthraceneyl.

[0052] In addition, when a polymer with a partial structure as shown in formula (1) has multiple Ar atoms in its molecule, they can be the same or different from each other.

[0053] Polymers having a partial structure as shown in formula (1) may contain a partial structure other than that partial structure in an amount (e.g., less than 50 mol%, less than 30 mol%, less than 20 mol%, less than 10 mol%, or less than 5 mol%) without impairing the effects of the present invention.

[0054] The mass ratio of Ar groups to the polymer as a whole is typically 1:0.1 to 1:0.5, preferably 1:0.15 to 1:0.4.

[0055] The weight-average molecular weight Mw of polymers having the partial structure shown in formula (1) is typically 4400 or less, preferably 2200 or less, more preferably 1100 or less, and typically 500 or more.

[0056] [Synthesis Method]

[0057] Polymers having a partial structure as shown in formula (1) can be obtained by reacting a main-chain polymer having at least one epoxy group in the molecule with an aromatic carboxylic acid under appropriate conditions.

[0058] Examples of main-chain polymers having at least one epoxy group within the molecule include...

[0059]

[0060] E: glycidyloxy group

[0061]

[0062] E: Glycidyloxy group

[0063]

[0064] E: glycidyloxy group

[0065] For example, it can be obtained under the trade name NC-7300L (manufactured by Nippon Kayaku Co., Ltd.). Furthermore, aromatic units without glycidyl groups may be included, provided that the effects of the invention are not impaired.

[0066] Examples of aromatic carboxylic acids include benzoic acid, 1-naphthoic acid, 9-anthracarboxylic acid, and 1-pyrenic acid.

[0067] The reaction can be carried out in a suitable solvent and in the presence of a suitable catalyst.

[0068] There are no particular restrictions on the solvent, as long as it can uniformly dissolve the aforementioned main-chain polymers and aromatic carboxylic acids having at least one epoxy group in the molecule, and does not hinder the reaction or induce side reactions.

[0069] Examples include, for instance, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, 2-hydroxyisobutyrate, etc. Ethyl butyrate, ethyl ethoxylate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used alone or in combination of two or more. Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, and cyclohexanone are preferred.

[0070] Examples of catalysts include quaternary ammonium salts such as tetrabutylammonium bromide, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide, and phosphine compounds such as triphenylphosphine. Ethyltriphenylphosphonium bromide is preferred.

[0071] The reaction temperature is typically between 40℃ and 200℃. The reaction time varies depending on the reaction temperature, but is usually between 30 minutes and 50 hours.

[0072] In addition, to prevent unreacted acid, catalyst, passivated catalyst, etc. from remaining in the reaction system, cation exchange resin or anion exchange resin for catalysts can be used.

[0073] [solvent]

[0074] As a solvent for the resist underlayer film forming composition of the present invention, any solvent capable of dissolving the above-mentioned reaction products can be used without particular limitation. In particular, since the resist underlayer film forming composition of the present invention is used in a uniform solution state, considering its coating performance, it is recommended to use solvents commonly used in photolithography processes.

[0075] Examples of such solvents include methyl cellolytic acetate, ethyl cellolytic acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl isobutyl methanol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl 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 ethoxylate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, and ethyl 3-methoxypropionate. 3-Ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate Esters, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, pentyl formate, isoamyl formate, methyl acetate, ethyl acetate, pentyl 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 hydroxyethyl acetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyethyl acetate, ethyl ethoxyethyl acetate, 3- Methyl 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, γ-butyrolactone, etc. These solvents can be used alone or in combination of two or more.

[0076] Alternatively, the following compounds described in WO2018 / 131562A1 may also be used.

[0077]

[0078] (R in equation (i)) 1 R 2 and R 3These represent hydrogen atoms and alkyl groups with 1 to 20 carbon atoms, which can be interrupted by oxygen, sulfur, or amide bonds. They can be the same or different and can bond together to form a ring structure.

[0079] Alkyl groups having 1 to 20 carbon atoms can be categorized as straight-chain or branched alkyl groups, with or without substituents, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, n-octyl, cyclohexyl, 2-ethylhexyl, n-nonyl, isononyl, p-tert-butylcyclohexyl, n-decyl, n-dodecylnonyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, nonadecanyl, and eicosyl. Alkyl groups having 1 to 12 carbon atoms are preferred, alkyl groups having 1 to 8 carbon atoms are more preferred, and alkyl groups having 1 to 4 carbon atoms are even more preferred.

[0080] Alkyl groups having 1 to 20 carbon atoms whose number is interrupted by oxygen, sulfur, or amide bonds can be exemplified by, for example, alkyl groups containing the structural units -CH2-O-, -CH2-S-, -CH2-NHCO-, or -CH2-CONH-. -O-, -S-, -NHCO-, or -CONH- can be one or more units in the aforementioned alkyl groups. Specific examples of alkyl groups with 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, butylaminocarbonyl, etc., and further include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, or octadecyl, and these are substituted by methoxy, ethoxy, propoxy, butoxy, methylthio, ethylthio, propylthio, butylthio, methylcarbonylamino, ethylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, etc. Preferably, methoxy, ethoxy, or methylthio, more preferably methoxy or ethoxy.

[0081] Because these solvents have relatively high boiling points, they are also effective in imparting high embedding and high planarization properties to compositions used for forming etchant underlayer films.

[0082] The following are specific examples of the preferred compounds represented by formula (i).

[0083]

[0084] Among the above compounds, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and the following formula

[0085]

[0086] The compounds shown are preferred, and 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutyramide are particularly preferred as compounds of formula (i).

[0087] These solvents can be used alone or in combination of two or more. Among these solvents, those with a boiling point above 160°C 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-dimethyldiacetate (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.

[0088] [Cross-linking agent component]

[0089] The resist underlayer film forming composition of the present invention may include a crosslinking agent component. Examples of such crosslinking agents include melamine derivatives, substituted ureas, or polymers thereof. Preferably, the crosslinking agent has at least two crosslinking-forming substituents, such as methoxymethylated glycourea (e.g., tetramethoxymethylated glycourea), butoxymethylated glycourea, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, or methoxymethylated thiourea. Condensates of these compounds may also be used.

[0090] Furthermore, as the aforementioned crosslinking agent, a crosslinking agent with high heat resistance can be used. Preferably, a compound containing a crosslinking-forming substituent is used, wherein the compound containing the crosslinking-forming substituent has an aromatic ring (e.g., a benzene ring, naphthalene ring) within its molecule.

[0091] The compound can be listed as a compound having a partial structure of the following formula (4), a polymer or oligomer having a repeating unit of the following formula (5).

[0092]

[0093] The above R 11 R 12 R 13 and R 14 It is an alkyl group having 1 to 10 hydrogen atoms or carbon atoms, and the examples above can be used for these alkyl groups.

[0094] The following examples illustrate compounds, polymers, and oligomers of formulas (4) and (5).

[0095]

[0096]

[0097] The above-mentioned compounds can be obtained as products of Asahi Organic Materials Co., Ltd. and Honshu Chemical Industry Co., Ltd. For example, among the above-mentioned crosslinking agents, the compound of formula (4-23) can be obtained by Honshu Chemical Industry Co., Ltd. under the trade name TMOM-BP, and the compound of formula (4-24) can be obtained by Asahi Organic Materials Co., Ltd. under the trade name TM-BIP-A.

[0098] The amount of crosslinking agent added varies depending on the coating solvent used, the substrate used, the required solution viscosity, the required film shape, etc., and is 0.001% by mass or more, 0.01% by mass or more, 0.05% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, or 80% by mass or less, 50% by mass or less, 40% by mass or less, 20% by mass or less, or 10% by mass or less relative to the total solids. These crosslinking agents sometimes undergo crosslinking reactions due to self-condensation, but when crosslinking substituents are present in the polymers of the present invention, they can undergo crosslinking reactions with these crosslinking substituents.

[0099] [Acids and / or acid-producing agents]

[0100] The composition for forming the resist underlayer film of the present invention may contain acid and / or acid-generating agent.

[0101] Examples of acids include p-toluenesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid pyridinium salt, phenolsulfonic acid pyridinium salt, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthoic acid.

[0102] One acid may be used alone, or two or more may be used in combination. The amount of acid used relative to the total solids is typically 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.01 to 5% by mass.

[0103] Examples of acid-producing agents include thermal acid-producing agents and photo-producing acid-producing agents.

[0104] Examples of heat-generating acid agents include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, K-PURE (registered trademark) CXC-1612, K-PURE CXC-1614, K-PURE TAG-2172, K-PURE TAG-2179, K-PURE TAG-2678, K-PURE TAG2689, K-PURE TAG2700 (manufactured by King Industries), and SI-45, SI-60, SI-80, SI-100, SI-110, SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd.), and other organic alkyl sulfonic acid esters.

[0105] The photoacid generator produces acid when the photoresist is exposed. Therefore, the acidity of the lower film can be adjusted. This is a method to match the acidity of the lower film with that of the upper photoresist. Furthermore, by adjusting the acidity of the lower film, the pattern shape of the photoresist formed on the upper layer can be adjusted.

[0106] Examples of photoacid-generating agents included in the resist lower film forming composition of the present invention include onium salt compounds, sulfonylimide compounds, and disulfonyldiazomethane compounds.

[0107] Examples of ononium salt compounds include diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoron-butanesulfonate, diphenyliodonium perfluoron-octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, as well as sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoron-butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0108] Examples of sulfonylimide compounds include, for example, N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluorobutanyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalenediformimide.

[0109] Examples of disulfonyl diazonium compounds include, for example, bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyl diazonium.

[0110] Acid-producing agents can be used in isolation or in combination of two or more.

[0111] When using an acid-generating agent, the proportion of the acid-generating agent is 0.01 to 10 parts by weight, or 0.1 to 8 parts by weight, or 0.5 to 5 parts by weight, relative to 100 parts by weight of the solids of the composition for forming the lower layer of the resist film.

[0112] [Other ingredients]

[0113] In the resist lower film forming composition of the present invention, a surfactant may be incorporated to further improve the coating properties against surface unevenness in order to prevent the generation of pinholes, streaks, etc. Examples of surfactants include, for instance, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oil-based ether; polyoxyethylene alkyl aryl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; polyoxyethylene-polyoxypropylene block copolymers; sorbitol fatty acid esters such as sorbitol monolaurate, sorbitol monopalmitate, sorbitol monostearate, sorbitol monooleate, sorbitol trioleate, and sorbitol tristearate; and polyoxyethylene sorbitol monolaurate, polyoxyethylene sorbitol monopalmitate, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol trioleate, and polyoxyethylene sorbitol tristearate. Nonionic surfactants such as esters, polyoxyethylene dehydrated sorbitol fatty acid esters, etc., including Eftop EF301, EF303, EF352 (manufactured by Tokem Produktsu Co., Ltd., trade name), Megafack F171, F173, R-40, R-40N, R-40LM (manufactured by DIC Co., Ltd., trade name), and Florad FC430, FC. Fluoropolymer surfactants such as 431 (manufactured by Sumitomo Silem Co., Ltd., trade name), Asahigard AG710, Servolon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by Asahi Glass Co., Ltd., trade name), and organosiloxane polymer-KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.) are used. The amount of these surfactants in the formulation is typically 2.0% by mass or less, preferably 1.0% by mass or less, relative to the total solids of the photoresist underlayer film material. These surfactants can be used alone or in combination of two or more. When using surfactants, the proportion is 0.0001 to 5 parts by mass, 0.001 to 1 part by mass, or 0.01 to 0.5 parts by mass relative to 100 parts by mass of the solids of the photoresist underlayer film forming composition.

[0114] In the resist underlayer film forming composition of the present invention, light absorbers, rheology modifiers, adhesive bonding aids, etc., may be added. Rheology modifiers are effective in improving the flowability of the underlayer film forming composition. Adhesive bonding aids are effective in improving the adhesion between the semiconductor substrate or the resist and the underlayer film.

[0115] As light absorbers, commercially available light absorbers listed in publications such as *Technology and Market of Industrial Pigments* (CMC Publishing) or *Dye Handbook* (edited by the Organic Synthetic Chemistry Society) can be used, 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 CI 31, 44, 57, 72 and 73; CI Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; CI Disperse Violet 43; CI Disperse Blue 96; CI Fluorescent Brightener 112, 135 and 163; CI Solvent Orange 2 and 45; CI Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49; CI Pigment Green 10; CI Pigment Brown 2, etc. The above-mentioned light absorbers are generally formulated in a proportion of 10% by mass or less, preferably 5% by mass or less, relative to the total solids of the composition for forming the resist underlayer film.

[0116] Rheology modifiers are mainly added to improve the flowability of the composition for forming the lower layer of the resist film, especially to improve the uniformity of the film thickness of the lower layer of the resist film and to improve the filling ability of the composition for forming the lower layer of the resist film to the pores during the baking process. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives such as di-n-butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyl decyl adipate; maleic acid derivatives such as di-n-butyl maleate, diethyl maleate, and dinonyl maleate; oleic acid derivatives such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate; or stearic acid derivatives such as n-butyl stearate and glyceryl stearate. These rheology modifiers are typically formulated in proportions of less than 30% by mass relative to the total solids of the composition used for forming the resist underlayer film.

[0117] Adhesion aids are primarily added to improve the adhesion between the substrate or resist and the composition used for forming the underlying film of the resist, especially to prevent the resist from peeling off during development. Specific examples include chlorosilanes such as trimethylchlorosilane, dimethylhydroxymethylchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylhydroxymethylethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane; and alkoxysilanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilyl... Silazane compounds such as silyl imidazoles; silane compounds such as hydroxymethyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-epoxypropoxypropyltrimethoxysilane; heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, and mercaptopyrimidine; ureas such as 1,1-dimethylurea and 1,3-dimethylurea; or thiourea compounds. These adhesive aids are typically formulated in proportions of less than 5% by mass, preferably less than 2% by mass, relative to the total solids of the composition for forming the resist underlayer.

[0118] The solids content of the resist underlayer film forming composition involved in this invention is typically set to 0.1–70% by mass, preferably 0.1–60% by mass. Solids content refers to the percentage of all components in the resist underlayer film forming composition after removing the solvent. The preferred proportions of the polymer in the solids are 1–100% by mass, 1–99.9% by mass, 50–99.9% by mass, 50–95% by mass, and 50–90% by mass, respectively.

[0119] One criterion for evaluating whether a composition for forming a resist underlayer film is a homogeneous solution is to observe the permeability of a specific microfilter. However, the composition for forming a resist underlayer film of the present invention passes through a microfilter with a pore size of 0.2 μm and exhibits a homogeneous solution state.

[0120] As materials for the aforementioned microfilters, examples include fluorinated 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, but PTFE (polytetrafluoroethylene) is preferred.

[0121] [Resist underlayer film and semiconductor device manufacturing method]

[0122] The following describes a method for manufacturing a photoresist underlayer film and a semiconductor device using the photoresist underlayer film formation composition of the present invention.

[0123] The resist underlayer film formation composition of the present invention is applied to a substrate used in the manufacture of semiconductor devices (e.g., silicon wafer substrate, silicon / silicon dioxide coated substrate, silicon nitride substrate, glass substrate, ITO substrate, polyimide substrate, and low-k material coated substrate, etc.) using a suitable coating method such as a spin coater or a coating machine, and then formed by firing. The firing conditions are appropriately selected from a firing temperature of 80°C to 400°C and a firing time of 0.3 to 60 minutes. Preferably, the firing temperature is 150°C to 350°C and the firing time is 0.5 to 2 minutes. Here, the film 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.

[0124] Alternatively, an inorganic photoresist underlayer film (hard mask) can also be formed on the organic photoresist underlayer film of the present invention. For example, in addition to the method for forming a silicon-containing photoresist underlayer film (inorganic photoresist underlayer film) composition by spin coating as described in WO2009 / 104552A1, Si-based inorganic material films can also be formed by CVD or the like.

[0125] Furthermore, by applying the resist underlayer film forming composition of the present invention onto a semiconductor substrate (so-called high-low difference substrate) having a high-low difference portion and a low-low difference portion, and then firing it, a resist underlayer film with a high-low difference portion and a low-low difference portion having a high-low difference portion in the range of 3 to 70 nm can be formed.

[0126] Next, a photoresist film, such as a photoresist layer, is formed on the lower photoresist film. The photoresist layer can be formed by a known method, namely, coating a photoresist composition solution onto the lower film and firing it. The thickness of the photoresist film is, for example, 50–10000 nm, 100–2000 nm, or 200–1000 nm.

[0127] As a photoresist formed on the underlying layer of the resist film, there are no particular restrictions as long as it is a photoresist that is photosensitive for use in exposure. Both negative and positive photoresists can be used. Examples include positive photoresists formed from phenolic varnish resin and 1,2-naphthoquinone diazonium sulfonate; chemically amplified photoresists formed from binders and photoacid generators containing groups that increase the rate of alkali dissolution by acid decomposition; chemically amplified photoresists formed from low-molecular-weight compounds that increase the rate of alkali dissolution by acid decomposition; alkali-soluble binders and photoacid generators; and chemically amplified photoresists formed from binders containing groups that increase the rate of alkali dissolution by acid decomposition; low-molecular-weight compounds that increase the rate of alkali dissolution by acid decomposition; and photoacid generators. For example, examples include APEX-E manufactured by Sipre Co., Ltd., PAR710 manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 manufactured by Shin-Etsu Chemical Co., Ltd. Additionally, examples include fluorinated atom polymer photoresists described in Proc.SPIE Vol.3999 330-334(2000), Proc.SPIE Vol.3999357-364(2000), and Proc.SPIE Vol.3999 365-374(2000).

[0128] Next, a resist pattern is formed by irradiation and development with light or electron beams. First, exposure is performed through a prescribed mask. Near-ultraviolet, far-ultraviolet, or extreme ultraviolet light (e.g., EUV (wavelength 13.5 nm)) is used for exposure. Specifically, KrF excimer lasers (wavelength 248 nm), ArF excimer lasers (wavelength 193 nm), and F2 excimer lasers (wavelength 157 nm) can be used. Among these, ArF excimer lasers (wavelength 193 nm) and EUV (wavelength 13.5 nm) are preferred. After exposure, post-exposure baking may be performed as needed. 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.

[0129] Furthermore, in this invention, an electron beam lithography resist can be used instead of a photoresist as the resist. Both negative and positive electron beam resists can be used. Types include chemically amplified resists formed from an acid-generating agent and a binder having groups that change the rate of alkali dissolution through acid decomposition; chemically amplified resists formed from an alkali-soluble binder, an acid-generating agent, and a low-molecular-weight compound that changes the rate of alkali dissolution through acid decomposition; chemically amplified resists formed from an acid-generating agent, a binder having groups that change the rate of alkali dissolution through acid decomposition, and a low-molecular-weight compound that changes the rate of alkali dissolution through acid decomposition; non-chemically amplified resists formed from a binder having groups that change the rate of alkali dissolution through electron beam decomposition; and non-chemically amplified resists formed from a binder having portions that change the rate of alkali dissolution through electron beam cutting. When using these electron beam resists, the irradiation source can be set to an electron beam, and the resist pattern can be formed in the same manner as when using a photoresist.

[0130] Next, development is performed using a developer. Thus, for example, when using a positive photoresist, the photoresist in the exposed areas is removed, forming a photoresist pattern.

[0131] Examples of suitable developing solutions include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, as well as alkaline aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine. Furthermore, surfactants may be added to these developing solutions. Developing conditions can be appropriately selected from a temperature range of 5–50°C and a development time range of 10–600 seconds.

[0132] Then, using the patterned photoresist (upper layer) as a protective film, the inorganic lower layer (intermediate layer) is removed. Next, using the film composed of the patterned photoresist and the inorganic lower layer (intermediate layer) as a protective film, the organic lower layer (lower layer) is removed. Finally, using the patterned inorganic lower layer (intermediate layer) and organic lower layer (lower layer) as protective films, the semiconductor substrate is processed.

[0133] First, the inorganic lower layer (intermediate layer), to which the photoresist has been removed, is removed by dry etching, exposing the semiconductor substrate. Gases that can be used in the dry etching of the inorganic lower layer include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, chlorine trifluoride, chlorine, trichloroborane, and dichloroborane. Halogen gases are preferred for the dry etching of the inorganic lower layer, and fluorine gases are more preferred. Examples of fluorine gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0134] Then, the organic underlayer is removed using a film consisting of patterned photoresist and an inorganic underlayer as a protective film. The organic underlayer (underlayer) is preferably removed by dry etching using an oxygen-based gas. This is because the inorganic underlayer, containing a large number of silicon atoms, is difficult to remove by dry etching using an oxygen-based gas.

[0135] Finally, the semiconductor substrate is processed. The semiconductor substrate is preferably processed by dry etching using fluorine-based gases.

[0136] Examples of fluorine gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0137] Furthermore, an organic antireflective film can be formed on top of the photoresist layer before the photoresist is formed. Therefore, there are no particular limitations on the antireflective film composition used here, and any antireflective film composition conventionally used in photolithography processes can be selected. In addition, the antireflective film can be formed by conventional methods, such as coating with a spin coater or a coating machine and then firing.

[0138] In this invention, an organic underlayer film can be formed on a substrate, followed by an inorganic underlayer film, and then a photoresist can be coated onto it. This narrows the pattern width of the photoresist, allowing substrate processing even when the photoresist is thinly coated to prevent pattern collapse, by selecting an appropriate etching gas. For example, a fluorine-based gas that achieves a sufficiently fast etching rate for the photoresist can be used as the etching gas to process the underlayer film; alternatively, a fluorine-based gas that achieves a sufficiently fast etching rate for the inorganic underlayer film can be used as the etching gas to process the substrate; and furthermore, an oxygen-based gas that achieves a sufficiently fast etching rate for the organic underlayer film can be used as the etching gas to process the substrate.

[0139] Furthermore, the photoresist underlayer film formed from the photoresist underlayer film forming composition sometimes absorbs light depending on the wavelength of the light used in the photolithography process. In such cases, it can function as an anti-reflective film that prevents reflected light from the substrate. Furthermore, the underlayer film formed from the photoresist 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 to prevent interaction between the substrate and the photoresist, a layer to prevent adverse effects on the substrate from materials used in the photoresist or substances generated during photoresist exposure, a layer to prevent the diffusion of substances generated from the substrate during heating and firing onto the upper photoresist, and a barrier layer to reduce the poisoning effect of the photoresist layer caused by the dielectric layer of the semiconductor substrate.

[0140] Furthermore, the lower layer film formed from the resist lower layer film formation composition is suitable for substrates with through-holes used in dual damascene processes, and can be used as an embedding material capable of filling holes without gaps. Additionally, it can also be used as a planarization material for planarizing the surface of semiconductor substrates with uneven surfaces.

[0141] Example

[0142] Hereinafter, specific examples of the composition for forming the resist underlayer of the present invention will be described using the following embodiments, but the present invention is not limited thereto.

[0143] List the apparatus used to determine the weight-average molecular weight of the reaction products obtained in the following synthetic examples.

[0144] Device: HLC-8320GPC manufactured by Higashi Sou Corporation

[0145] GPC column: TSKgel Super-MultiporeHZ-N (2 columns)

[0146] Column temperature: 40℃

[0147] Flow rate: 0.35 ml / min

[0148] Elution buffer: THF

[0149] Standard sample: Polystyrene

[0150] The chemical structures (examples) and abbreviations of the main raw materials used are as follows.

[0151]

[0152] <Synthesis example 1>

[0153] 6.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 4.91 g of 1-naphthoic acid (manufactured by Tokyo Kasei Corporation), and 0.26 g of ethyltriphenylphosphonium bromide as a catalyst were added to 26.07 g of propylene glycol monomethyl ether (hereinafter referred to as PGME in this specification). The mixture was reacted at 140°C for 24 hours to obtain a solution containing the reaction product. 12.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachitecnos Co., Ltd.) and 12.00 g of cation exchange resin (product name: Amberlist [registered trademark] 15JWET, Organo Co., Ltd.) were added, and the mixture was stirred at 25°C to 30°C for 4 hours before filtration.

[0154] The obtained reaction product was subjected to GPC analysis, and the weight-average molecular weight after conversion to standard polystyrene was 770. The obtained reaction product is presumed to be a copolymer having the structural units shown in the following formula (1).

[0155]

[0156] <Synthesis example 2>

[0157] Add 6.00g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 6.33g of 9-anthracarboxylic acid (manufactured by Midori Kagaku Co., Ltd.), and 0.26g of ethyltriphenylphosphonium bromide as a catalyst to 26.07g of PGME, and react at 140°C for 24 hours to obtain a solution containing the reaction products. Add 13.00g of anion exchange resin (manufactured by Dowex MONOSPHERE 550A, Muromachitecnos Co., Ltd.) and 13.00g of cation exchange resin (manufactured by Amberlist 15JWET, Organo Co., Ltd.), and stir at 25°C–30°C for 4 hours, then filter.

[0158] The obtained reaction product was subjected to GPC analysis, and the weight-average molecular weight converted to standard polystyrene was 830. The obtained reaction product is presumed to be a copolymer having the structural units shown in the following formula (2).

[0159]

[0160] <Synthesis example 3>

[0161] Add 6.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 3.48 g of benzoic acid (manufactured by Tokyo Kasei Corporation), and 0.26 g of ethyltriphenylphosphonium bromide as a catalyst to 22.74 g of PGME, and react at 140 °C for 24 hours to obtain a solution containing the reaction products. Add 10.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachitecnos Co., Ltd.) and 10.00 g of cation exchange resin (product name: Amberlist [registered trademark] 15JWET, Organo Co., Ltd.), stir at 25 °C to 30 °C for 4 hours, and then filter.

[0162] The obtained reaction product was subjected to GPC analysis, and the weight-average molecular weight converted to standard polystyrene was 750. The obtained reaction product is presumed to be a copolymer having the structural unit shown in the following formula (4).

[0163]

[0164] <Synthesis example 4>

[0165] Add 5.00 g of NC-7300L (manufactured by Nippon Kayaku Co., Ltd.), 5.85 g of 1-pyrene carboxylic acid (manufactured by Tokyo Kasei Corporation), and 0.22 g of ethyltriphenylphosphonium bromide as a catalyst to 25.83 g of PGME, and react at 140 °C for 24 hours to obtain a solution containing the reaction product. Add 11.00 g of anion exchange resin (product name: Dowex [registered trademark] MONOSPHERE [registered trademark] 550A, Muromachitecnos Co., Ltd.) and 11.00 g of cation exchange resin (product name: Amberlist [registered trademark] 15JWET, Organo Co., Ltd.), stir at 25 °C to 30 °C for 4 hours, and then filter.

[0166] GPC analysis of the obtained reaction products showed that the weight-average molecular weight converted to standard polystyrene was 720. The obtained reaction products were presumed to be copolymers having the structural units shown in the following formula (5).

[0167]

[0168] <Comparative Synthesis Example 1>

[0169] 7.57 g of PGME was added to 17.67 g of propylene glycol monomethyl ether acetate (hereinafter referred to as PGMEA in this specification), 5.00 g of EHPE-3150 (manufactured by Daicel Co., Ltd.), 3.11 g of 9-anthracarboxylic acid, 2.09 g of benzoic acid, and 0.62 g of ethyltriphenylphosphonium bromide. The mixture was heated under nitrogen atmosphere and refluxed for 13 hours. 16 g of cation exchange resin (manufactured by Organo Co., Ltd.) and 16 g of anion exchange resin (manufactured by MONOSPHERE 550A, registered trademark of Dunex Co., Ltd.) were added to the resulting solution. The mixture was stirred at 25°C–30°C for 4 hours and then filtered.

[0170] GPC analysis of the obtained reaction products showed that the weight-average molecular weight converted to standard polystyrene was 4700. The obtained reaction products were presumed to be copolymers having the structural units shown in the following formula (3).

[0171]

[0172] (Formulation of the composition for forming the lower layer film of the resist)

[0173] <Example 1>

[0174] In the above-described synthesis example 1, 4.90 g of a solution containing 1.26 g of copolymer (solvent: PGME, solids: 25.74% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.) 1% by mass PGME solution, 6.66 g of PGME, 5.54 g of PGMEA, and 0.13 g of surfactant (manufactured by DIC Co., Ltd., trade name R-30N) 1% by mass PGME solution, forming a 7.7% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a composition for forming a resist lower film.

[0175] <Example 2>

[0176] In the above-described synthesis example 2, 4.63 g of a solution containing 1.26 g of copolymer (solvent: PGME, solids: 27.23% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.) 1% by mass PGME solution, 6.93 g of PGME, 5.54 g of PGMEA, and 0.13 g of surfactant (manufactured by DIC Co., Ltd., trade name R-30N) 1% by mass PGME solution, forming a 7.7% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a composition for forming a resist lower film.

[0177] <Example 3>

[0178] In the above-described synthesis example 3, 5.06 g of a solution containing 1.26 g of copolymer (solvent: PGME, solids: 24.95% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.) 1% by mass PGME solution, 6.51 g of PGME, 5.54 g of PGMEA, and 0.13 g of surfactant (manufactured by DIC Co., Ltd., trade name R-30N) 1% by mass PGME solution, forming a 7.7% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a composition for forming a resist lower film.

[0179] <Example 4>

[0180] In the above-described synthesis example 4, 4.19 g of a solution containing 1.26 g of copolymer (solvent: PGME, solids: 30.12% by mass) was mixed with 0.25 g of TMOM-BP (manufactured by Honshu Chemical Industry Co., Ltd.), 2.52 g of K-PURE (registered trademark) TAG2689 (manufactured by King Industries Co., Ltd.) 1% by mass PGME solution, 7.37 g of PGME, 5.54 g of PGMEA, and 0.13 g of surfactant (manufactured by DIC Co., Ltd., trade name R-30N) 1% by mass PGME solution, forming a 7.7% by mass solution. This solution was filtered using a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a composition for forming a resist lower film.

[0181] <Comparative Example 1>

[0182] In a solution containing 4.51 g of the copolymer obtained in Comparative Synthesis Example 1 (the solvent was a PGME / PGMEA mixed solvent used in the synthesis, with a solid content of 23.26% by mass), 1.14 g of tetramethoxymethyl urea (product name: POWDERLINK (registered trademark) 1174, manufactured by Nippon Saitek Industries Co., Ltd.), 3.41 g of a 1% by mass PGME solution of p-toluenesulfonic acid pyridinium salt, 50.68 g of PGME, 14.80 g of PGMEA, and 0.45 g of a 1% by mass PGME solution of surfactant (manufactured by DIC Co., Ltd., trade name R-30) were mixed to form a 6.35% by mass solution. This solution was filtered through a polytetrafluoroethylene microfilter with a pore size of 0.2 μm to prepare a composition for forming a resist lower film.

[0183] (Dissolution test in photoresist solvent)

[0184] The resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1 were respectively coated onto silicon wafers using a spin coater. Then, they were baked on a hot plate at the temperatures shown in Table 1 below for 1 minute to form a resist underlayer film (film thickness 0.2 μm). These resist underlayer films were immersed in a PGME / PGMEA mixed solvent (mass mixing ratio 70 / 30) used as the photoresist solution, and it was confirmed that they were insoluble in the solvent. The results are indicated by “○” in Table 1 below.

[0185] (Optical parameter testing)

[0186] The resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1 were respectively coated onto silicon wafers using a spin coater. Then, they were baked on a hot plate at the temperatures shown in Table 1 below for 1 minute to form a resist underlayer film (film thickness 0.2 μm). The refractive index (n value) and attenuation coefficient (k value) at a wavelength of 193 nm were then measured using an optical ellipsometer (JAWoollam, VUV-VASE VU-302). The results are shown in Table 1 below. To ensure sufficient anti-reflective function of the above resist underlayer film, the k value at a wavelength of 193 nm is preferably 0.1 to 0.4.

[0187] (Determination of dry etching rate)

[0188] Using the resist underlayer film forming compositions prepared in Examples 1 to 4 and Comparative Example 1, resist underlayer films were formed on a silicon wafer using the same method as described above. Then, the dry etching rate of these resist underlayer films was measured using a RIE system manufactured by Samco Corporation under conditions of using CF4 as the dry etching gas. The dry etching rate of each resist underlayer film was calculated when the dry etching rate of Comparative Example 1 was considered as 1.00. The results are listed in Table 1 below as "relative dry etching rates". The dry etching rate of the resist underlayer films formed using the resist underlayer film forming compositions prepared in Examples 1 to 2 is significantly slower than that of Comparative Example 1, thus demonstrating that this resist underlayer film forming composition can be easily used as a mask for substrate processing.

[0189] Table 1

[0190]

[0191] [Embedded evaluation]

[0192] Embedding was confirmed in a dense patterned region with a SiO2 substrate of 200 nm thickness, a trench width of 50 nm, and a spacing of 100 nm. The resist underlayer film forming compositions prepared in Examples 1 to 2 and Comparative Examples 1 to 3 were coated onto the aforementioned substrates and then fired under specified conditions to form a resist underlayer film of approximately 200 nm. The planarization of the substrates was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High Tech Noroze Co., Ltd. to confirm whether the resist underlayer film forming composition filled into the pattern. The results for Examples 1 to 2 and Comparative Examples 2 to 3 were good, but voids were confirmed in Comparative Example 1.

[0193] [Coating test on substrates with uneven surfaces]

[0194] To evaluate the coating thickness of the high-gradient coating, the coating thickness of densely patterned regions (DENSE) with trench widths of 50 nm and spacing of 100 nm was compared with that of unpatterned open regions (OPEN) on a SiO2 substrate with a film thickness of 200 nm. The resist underlayer film forming compositions of Examples 1 to 2 and Comparative Examples 1 to 3 were coated on the above-mentioned substrates with a film thickness of 150 nm and then fired at a specified temperature. The high-gradient coating thickness of the substrate was observed using a scanning electron microscope (S-4800) manufactured by Hitachi High Tech Noroze Co., Ltd., and the film thickness difference between the dense regions (patterned areas) and open regions (unpatterned areas) of the high-gradient substrate was measured (the coating thickness difference between the dense and open regions, referred to as Bias), thereby evaluating the planarization. The film thickness and coating thickness difference values ​​for each region are shown in Table 2. Regarding flatness evaluation, the smaller the Bias value, the higher the flatness.

[0195] Table 2

[0196]

[0197] Industrial availability

[0198] According to the present invention, a resist underlayer film forming composition exhibiting high etch resistance, good dry etch rate ratio and optical constant, good coverage of so-called high-low difference substrates, small film thickness difference after embedding, and the ability to form a flat film can be provided; a resist underlayer film using the resist underlayer film forming composition; and a method for manufacturing a semiconductor device.

Claims

1. A composition for forming a resist underlayer film, comprising a polymer having a weight-average molecular weight Mw of 2200 or less having a partial structure as shown in formula (1) below, and a solvent; In the formula, Ar represents an aromatic group having 6 to 20 carbon atoms that has been single or multiplely substituted by at least one group selected from the group consisting of alkyl, fused-ring, heterocyclic, hydroxyl, amino, nitro, ether, alkoxy, cyano, and carboxyl groups having 1 to 20 carbon atoms, or an unsubstituted aromatic group having 6 to 20 carbon atoms. Polymers having a partial structure as shown in formula (1) are or The reaction product with aromatic carboxylic acids having 6 to 20 carbon atoms, whether substituted or unsubstituted.

2. The composition for forming a resist underlayer film according to claim 1, wherein Ar in formula (1) is phenyl, naphthyl, anthraceneyl, pyreneyl, or a combination thereof.

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

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

5. The composition for forming a resist underlayer film according to claim 1, comprising an acid and / or an acid-generating agent.

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

7. A resist underlayer film, characterized in that, It is a sintered product of a coating film formed by the composition for forming a resist underlayer film according to any one of claims 1 to 6.

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

Images