Composition for forming resist underlayer film

Abstract

[Problem] The purpose of the present invention is to provide a composition for forming a resist underlayer film, the composition being capable of forming a film which achieves good coverage of a substrate that has a level difference, thereby being flat and having a small film thickness difference after embedment, while exhibiting excellent hardness. [Solution] A composition for forming a resist underlayer film, the composition containing a solvent and a polymer that has at least one repeating unit represented by formula (1), formula (2), formula (3) or formula (4) (omitted). This composition for forming a resist underlayer film has high etching resistance, good dry etching rate ratio and optical constant, and forms a film that has excellent hardness, while achieving good coverage of a substrate that has a level difference, thereby being flat and having a small film thickness difference after embedment. Consequently, this composition for forming a resist underlayer film enables the achievement of finer substrate processing.

Description

Resist underlayer film-forming composition

[0001] The present invention relates to a resist underlayer film-forming composition capable of forming a resist underlayer film that has excellent filling properties, exhibits a good dry etching rate ratio and optical constants, has good coverage even on so-called uneven substrates, is flat, and has excellent hardness; a resist underlayer film using the resist underlayer film-forming composition; and a method for producing a semiconductor device.

[0002] In recent years, resist underlayer film materials for multilayer resist processes have been required to function as anti-reflection films, particularly for short wavelength exposure, have appropriate optical constants, and also have etching resistance during substrate processing, and the use of polymers having repeating units containing benzene rings has been proposed (Patent Document 1). Also, Patent Document 2 proposes the use of polymers obtained from aromatic rings and aldehyde compounds, but these are not necessarily sufficient in terms of optical constants.

[0003] JP 2004-354554 JP 2019-044022

[0004] To achieve thinner resist layers as resist patterns become finer, a lithography process is known in which at least two resist underlayer films are formed and used as a mask material. This involves providing at least one organic film (underlayer organic film) and at least one inorganic underlayer film on a semiconductor substrate, patterning the inorganic underlayer film using a resist pattern formed on an upper resist film as a mask, and then patterning the lower organic film using the pattern as a mask. This method is said to be capable of forming a pattern with a high aspect ratio. Materials for forming the at least two layers include organic resins (e.g., acrylic resins, novolac resins), inorganic materials (silicon resins (e.g., organopolysiloxanes), inorganic silicon compounds (e.g., SiON, SiO ２) and other combinations. Furthermore, in recent years, double patterning technology, which involves two lithography processes and two etching processes to obtain a single pattern, has been widely adopted, with the above-mentioned multilayer process being used in each step. In this case, the organic film deposited after the first pattern is formed must have the ability to flatten steps.

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

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

[0007] The present invention encompasses the following: 1. A resist underlayer film-forming composition containing a polymer having at least one repeating unit represented by the following formula (1), formula (2), formula (3) or formula (4), and a solvent. (In formulas (1) to (4), Ar １ , Ar ２ are each independently R １ , R ２ represents a benzene ring or a naphthalene ring which may be substituted by R １ and R ２ R each represents a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a combination thereof which may contain an ether bond, a ketone bond, or an ester bond. ３ is a tetravalent organic group having 1 to 2 carbon atoms, and R ４is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an alkynyl group having 2 to 3 carbon atoms. １ and n ２ are Ar １ , Ar ２ is an integer of 1 to 3 when Ar is a benzene ring; １ , Ar ２ When R is a naphthalene ring, it is an integer of 1 to 5. ５ represents an alkyl group having 2 to 10 carbon atoms. In formulas (3) and (4), X represents a single bond, a saturated or unsaturated linear or cyclic organic group having 1 to 30 carbon atoms which may contain a nitrogen atom, or an arylene group having 6 to 30 carbon atoms. 2. In formulas (1) to (4), Ar １ and Ar ２ 3. The resist underlayer film forming composition according to the above item 1, wherein R is a benzene ring. １ , R ２ are each a hydrogen atom. 4. The resist underlayer film-forming composition according to any one of items 1 to 3 above, further comprising a crosslinking agent. 5. The resist underlayer film-forming composition according to any one of items 1 to 4 above, further comprising an acid and / or an acid generator. 6. The resist underlayer film-forming composition according to any one of items 1 to 5 above, wherein the solvent has a boiling point of 160°C or higher. 7. The resist underlayer film is a baked product of a coating film made from the resist underlayer film-forming composition according to any one of items 1 to 6 above. 8. The method for manufacturing a semiconductor device includes the steps of: forming a resist underlayer film on a semiconductor substrate using the resist underlayer film-forming composition according to any one of items 1 to 6 above; forming a resist film on the formed resist underlayer film; irradiating the formed resist film with light or an electron beam and developing it to form a resist pattern; etching and patterning the resist underlayer film via the formed resist pattern; and processing a semiconductor substrate via the patterned resist underlayer film.

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

[0009] [Resist Underlayer Film Forming Composition] The resist underlayer film forming composition according to the present invention comprises a polymer having at least one repeating unit represented by the following formula (1), formula (2), formula (3) or formula (4): (In formulas (1) to (4), Ar １ , Ar ２ are each independently R １ , R ２ represents a benzene ring or a naphthalene ring which may be substituted by R １ and R ２ R each represents a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a combination thereof which may contain an ether bond, a ketone bond, or an ester bond. ３ is a tetravalent organic group having 1 to 2 carbon atoms, and R ４ is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an alkynyl group having 2 to 3 carbon atoms. １ and n ２ are Ar １ , Ar ２ is an integer of 1 to 3 when Ar is a benzene ring; １ , Ar ２ When R is a naphthalene ring, it is an integer of 1 to 5. ５represents an alkyl group having 2 to 10 carbon atoms. In formulas (3) and (4), X represents a single bond, a saturated or unsaturated linear or cyclic organic group having 1 to 30 carbon atoms which may contain a nitrogen atom, or an arylene group having 6 to 30 carbon atoms.) and a solvent.

[0010] [Polymer having at least one repeating unit represented by formula (1), formula (2), formula (3) or formula (4)] In the above formulas (1) to (4), Ar １ , Ar ２ are each independently R １ , R ２ represents a benzene ring or a naphthalene ring which may be substituted by R １ and R ２ R each represents a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a combination thereof which may contain an ether bond, a ketone bond, or an ester bond. ３ is a tetravalent organic group having 1 to 2 carbon atoms, and R ４ is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an alkynyl group having 2 to 3 carbon atoms. １ and n ２ are Ar １ , Ar ２ is an integer of 1 to 3 when Ar is a benzene ring; １ , Ar ２ When R is a naphthalene ring, it is an integer of 1 to 5. ５ represents a linear or branched alkyl group having 2 to 10 carbon atoms. In formulas (3) and (4), X represents a single bond, a saturated or unsaturated linear or cyclic organic group having 1 to 30 carbon atoms which may contain a nitrogen atom, or an arylene group having 6 to 30 carbon atoms.

[0011] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0012] Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a cyclobutyl group, a 1-methyl-cyclopropyl group, a 2-methyl-cyclopropyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, and a 1-ethyl-n-propyl group. , cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2 -dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,Examples include a 3-trimethyl-cyclopropyl group, a 1-ethyl-2-methyl-cyclopropyl group, a 2-ethyl-1-methyl-cyclopropyl group, a 2-ethyl-2-methyl-cyclopropyl group, and a 2-ethyl-3-methyl-cyclopropyl group. The alkyl groups having 1 to 3 carbon atoms and the alkyl groups having 2 to 10 carbon atoms are included in the above examples. The alkyl groups having 2 to 10 carbon atoms are preferably alkyl groups having 1 to 7 carbon atoms.

[0013] Examples of the alkenyl group having 2 to 10 carbon atoms include ethenyl, 1-propenyl, 2-propenyl, 1-methyl-1-ethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-n-propylethenyl, 1-methyl-1-butenyl, 1-methyl-2-butenyl, 1-methyl-3-butenyl, 2- Ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group, 2-methyl-3-pentenyl group, 2-methyl-4-pentenyl group, 2-n-propyl-2-propenyl group, 3-methyl-1-pentenyl group, 3-methyl-2-pentenyl group, 3-methyl-3-pentenyl group, 3-methyl-4-pentenyl group, 3-ethyl-3-butenyl group, 4-methyl-1-pentenyl group, 4-methyl-2-pentenyl group , 4-methyl-3-pentenyl group, 4-methyl-4-pentenyl group, 1,1-dimethyl-2-butenyl group, 1,1-dimethyl-3-butenyl group, 1,2-dimethyl-1-butenyl group, 1,2-dimethyl-2-butenyl group, 1,2-dimethyl-3-butenyl group, 1-methyl-2-ethyl-2-propenyl group, 1-s-butylethenyl group, 1,3-dimethyl-1-butenyl group, 1,3-dimethyl-2-butenyl group, 1,3-dimethyl-3-butenyl group, 1-i-butylethenyl group, 2,2-dimethyl-3-butenyl group, 2,3-dimethyl-1-butenyl group, 2,3-dimethyl-2-butenyl group, 2,3-dimethyl-3-butenyl group, 2-i-propyl-2-propenyl group, 3,3-dimethyl-1-butenyl group, 1-ethyl-1-butenyl group, 1-ethyl-2-butenyl group, 1-ethyl-3-butenyl group, 1-n-propyl-1-propenyl group, 1-n-propyl-2-propenyl group, 2-ethyl-1-butenyl group, 2-ethyl-2-butenyl group, 2-ethyl-3-butenyl group, 1,1,2-trimethyl-2-propenyl group, 1-t-butylethenyl group, 1-methyl-1-ethyl-2-propenyl group, 1-ethyl-2-methyl-1-propenyl group, 1-ethyl-2-methyl-2-propenyl group, 1-i-propyl-1-propenyl group, 1-i- Examples of alkenyl groups include propyl-2-propenyl group, 1-methyl-2-cyclopentenyl group, 1-methyl-3-cyclopentenyl group, 2-methyl-1-cyclopentenyl group, 2-methyl-2-cyclopentenyl group, 2-methyl-3-cyclopentenyl group, 2-methyl-4-cyclopentenyl group, 2-methyl-5-cyclopentenyl group, 2-methylene-cyclopentyl group, 3-methyl-1-cyclopentenyl group, 3-methyl-2-cyclopentenyl group, 3-methyl-3-cyclopentenyl group, 3-methyl-4-cyclopentenyl group, 3-methyl-5-cyclopentenyl group, 3-methylene-cyclopentyl group, 1-cyclohexenyl group, 2-cyclohexenyl group, and 3-cyclohexenyl group. The above-mentioned alkenyl groups having 2 or 3 carbon atoms are included in the above examples.

[0014] Examples of the alkynyl group having 2 or 3 carbon atoms include an ethynyl group and a 1-propynyl group.

[0015] Also R ３ is a tetravalent organic group having 1 to 2 carbon atoms, and R ４ is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an alkynyl group having 2 to 3 carbon atoms; R ３ and R ４ More specifically, the moiety includes, for example, the following groups. (* indicates the point of attachment to the nitrogen atom)

[0016] In the above formula (1) or (3) of the present invention, Ar １ and Ar２ is R １ , R ２ In the case where the repeating unit is a benzene ring substituted with, examples of the carbazole structure contained in the repeating unit include carbazole, N-methylcarbazole, N-ethylcarbazole, 1,3,6,8-tetranitrocarbazole, 3,6-diaminocarbazole, 3,6-dibromo-9-ethylcarbazole, 3,6-dibromo-9-phenylcarbazole, 3,6-dibromocarbazole, 3,6-dichlorocarbazole, 3-amino-9-ethylcarbazole, 3-bromo-9-ethylcarbazole, 4,4′bis(9H-carbazol-9-yl)biphenyl, 9-ethylcarbazole, 4-glycidylcarbazole, 4-hydroxybenzo ... carbazole, 9-(1H-benzotriazol-1-ylmethyl)-9H-carbazole, 9-acetyl-3,6-diiodocarbazole, 9-benzoylcarbazole, 9-benzoylcarbazole-6-dicarboxaldehyde, 9-benzylcarbazole-3-carboxaldehyde, 9-methylcarbazole, 9-phenylcarbazole, 9-vinylcarbazole, potassium carbazole, carbazole-N-carbonyl chloride, N-ethylcarbazole-3-carboxaldehyde, N-((9-ethylcarbazol-3-yl)methylene)-2-methyl-1-indolinylamine, and the like.

[0017] In the above general formula (3) or (4) of the present invention, X represents a single bond, a saturated or unsaturated linear or cyclic organic group having 1 to 30 carbon atoms which may contain a nitrogen atom, or an arylene group having 6 to 30 carbon atoms. In addition to a single bond, X can be represented by the following formula:

[0018] (* represents the bond end with carbon.) Particularly preferably, X is a single bond.

[0019] [Synthesis of polymer having at least one repeating unit represented by formula (1), formula (2), formula (3), or formula (4)] A polymer having at least one repeating unit represented by formula (1), formula (2), formula (3), or formula (4) can be produced, for example, by a method in which a compound represented by the following formula (1-a) or formula (2-a) is reacted with a compound represented by the following formula (3-a) or formula (4-a) to obtain a reaction product A, and then this reaction product A is reacted with a compound represented by formula (5-a). Of course, the synthesis of the above polymer is not limited to this reaction method. In the above formula, Ar １ , Ar ２ , R １ , R ２ , R ３ , R ４ , R ５ , X, the same as above. ９ represents an alkyl group having 1 to 10 carbon atoms or a haloalkyl group having 1 to 10 carbon atoms.

[0020] Examples of the carbazoles represented by the formula (1-a) include carbazole, N-methylcarbazole, N-ethylcarbazole, 1,3,6,8-tetranitrocarbazole, 3,6-diaminocarbazole, 3,6-dibromo-9-ethylcarbazole, 3,6-dibromo-9-phenylcarbazole, 3,6-dibromocarbazole, 3,6-dichlorocarbazole, 3-amino-9-ethylcarbazole, 3-bromo-9-ethylcarbazole, 4,4'bis(9H-carbazol-9-yl)biphenyl, 9-ethylcarbazole, 4-glycidylcarbazole, and 4-hydroxycarbazole. carbazole, 9-(1H-benzotriazol-1-ylmethyl)-9H-carbazole, 9-acetyl-3,6-diiodocarbazole, 9-benzoylcarbazole, 9-benzoylcarbazole-6-dicarboxaldehyde, 9-benzylcarbazole-3-carboxaldehyde, 9-methylcarbazole, 9-phenylcarbazole, 9-vinylcarbazole, potassium carbazole, carbazole-N-carbonyl chloride, N-ethylcarbazole-3-carboxaldehyde, N-((9-ethylcarbazol-3-yl)methylene)-2-methyl-1-indolinylamine, and the like. These may be used alone or in combination of two or more.

[0021] An example of the dialdehyde compound represented by the above general formula (3-a) can be represented by the following formula:

[0022]

[0023] Preferred dialdehyde compounds represented by formula (3-a) are those in which X is a single bond or a saturated or unsaturated, linear or cyclic organic group having 1 to 30 carbon atoms, which may contain a nitrogen atom. Dialdehyde compounds in which X is a single bond are particularly preferred. These dialdehyde compounds are readily available, which allows for reduction in the production costs of the resulting resist underlayer film composition.

[0024] Furthermore, equivalents of the dialdehyde compounds shown here can also be used. For example, the equivalents of the above general formula (3-a) include those of the following general formula: (X is defined as X above, and R' may be the same or different and is a monovalent hydrocarbon group having 1 to 10 carbon atoms.) (X is defined as X above, and R″ is a divalent hydrocarbon group having 1 to 10 carbon atoms.) Or, when a hydrogen atom is bonded to the α-carbon atom of the formyl group, (X' is an organic group having one less hydrogen atom than the above X, and R' is a monovalent hydrocarbon group having 1 to 10 carbon atoms.)

[0025] Specific examples of equivalents of the type of formula (3A) include: The same can be applied to other dialdehyde compounds.

[0026] Specific examples of equivalents of the type of formula (3B) include: The same can be applied to other dialdehyde compounds.

[0027] Specific examples of equivalents of the type of formula (3C) include: The same can be applied to other dialdehyde compounds.

[0028] The ratio of the compound of formula (1-a) or formula (2-a) to the dialdehyde compound of formula (3-a) is preferably 0.01 to 5 mol, more preferably 0.1 to 2 mol, per 1 mol of the compound of formula (1-a) or formula (2-a).

[0029] The resist underlayer film material of the present invention may contain at least one polymer obtained by condensing one or more compounds represented by the above formula (1-a) or formula (2-a) with one or more compounds represented by the above general formula (3-a) and / or their equivalents, to obtain a polymer (reaction product A), which is further reacted with a compound represented by formula (5-a).

[0030] The resist underlayer film material of the present invention may contain at least one polymer obtained by condensing an aromatic compound other than the compounds represented by formula (1-a) or (2-a) (hereinafter referred to as "other aromatic compound") with a compound represented by formula (3-a) to obtain a polymer (reaction product A), and further reacting the polymer with a compound represented by formula (5-a), within a range that does not impair the effects of the present invention. Examples of the other aromatic compound include phenols, naphthols, biphenols, polyhydric phenols, etc.

[0031] The reaction product A is a polymer obtained by condensing the compound represented by formula (1-a) or formula (2-a), or, if necessary, the other aromatic compounds, with the compound represented by formula (3-a). As described above, one or more of the compounds represented by formula (1-a) or formula (2-a) and the other aromatic compounds can be selected and used. Therefore, the polymer produced by further reacting the reaction product A with the compound represented by formula (5-a) can also be a multi-component copolymer. Furthermore, the compound represented by formula (1-a) or formula (2-a) and a monomer other than the compound represented by formula (3-a) may be reacted in an amount that does not impair the effects of the present invention (for example, less than 50 mol%, less than 30 mol%, less than 20 mol%, less than 10 mol%, or less than 5 mol%).

[0032] Examples of the acid catalyst used in the reaction include mineral acids such as sulfuric acid, phosphoric acid, and perchloric acid; organic sulfonic acids such as p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, and methanesulfonic acid; and carboxylic acids such as formic acid and oxalic acid. The amount of the acid catalyst used varies depending on the type of acid used. The amount is usually 0.001 to 10,000 parts by mass, preferably 0.01 to 1,000 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the compound represented by Formula (1-a) or Formula (2-a).

[0033] The above condensation reaction and addition reaction can be carried out without a solvent, but are usually carried out using a solvent. Any solvent that does not inhibit the reaction can be used. Examples of the solvent include ethers such as 1,2-dimethoxyethane, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, tetrahydrofuran, and dioxane.

[0034] During the reaction, a polymerization inhibitor (radical trapping agent) may be added as necessary. Specific examples of the polymerization initiator include 2,6-diisobutylphenol, 3,5-di-tert-butylphenol, 3,5-di-tert-butylcresol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, tert-butylcatechol, and 4-methoxy-1-naphthol. When a polymerization inhibitor is added, the amount added is preferably 1% by mass or less based on the total solid content.

[0035] The reaction temperature is usually 40° C. to 200° C. The reaction time varies depending on the reaction temperature, but is usually about 30 minutes to 50 hours. The weight-average molecular weight Mw of the polymer obtained as described above is usually 500 to 1,000,000, or 600 to 500,000.

[0036] Polymers suitable for use in the present invention will be described in the examples.

[0037] For the compound represented by formula (5-a), R ３ , R ４ is R in the above formulas (1) to (4). ３ , R ４ is the same as the definition of R ９ represents an alkyl group having 1 to 10 carbon atoms or a haloalkyl group having 1 to 10 carbon atoms, such as propargyl bromide, 2-butylyl bromide, 2-pentynyl chloride, and 1-chloro-2-octyne.

[0038] [Solvent] The solvent for the resist underlayer film-forming composition of the present invention is not particularly limited, as long as it can dissolve the polymer. In particular, since the resist underlayer film-forming composition of the present invention is used in the state of a homogeneous solution, it is recommended to use a solvent that is generally used in lithography processes in combination with the resist underlayer film-forming composition of the present invention, taking into consideration its coating performance.

[0039] 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 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 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,Examples of the solvent include 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, methyl isobutyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 4-methyl-2-pentanol, and γ-butyrolactone. These solvents can be used alone or in combination of two or more.

[0040] In addition, the following compounds described in WO2018 / 131562A1 can also be used. (R in formula (i) ６ , R ７ and R ８ each represents a hydrogen atom, an oxygen atom, a sulfur atom, or an alkyl group having 1 to 20 carbon atoms which may be interrupted by an amide bond, and may be the same or different from each other and may be bonded to each other to form a ring structure.

[0041] 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.

[0042] Examples of the alkyl group having 1 to 20 carbon atoms interrupted by an oxygen atom, a sulfur atom, or an amide bond include the structural unit -CH ２ —O—, —CH ２ -S-, -CH ２ -NHCO- or -CH ２Examples include those containing -CONH-. -O-, -S-, -NHCO- or -CONH- may be present in one unit or two or more units in the alkyl group. Specific examples of the alkyl group having 1 to 20 carbon atoms interrupted by an -O-, -S-, -NHCO- or -CONH- unit include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a methylcarbonylamino group, an ethylcarbonylamino group, a propylcarbonylamino group, a butylcarbonylamino group, a methylaminocarbonyl group, an ethylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, a propylaminocarbonyl group, a propylaminocarbonyl group, a methylaminocarbonyl group, a propylaminocarbonyl group, a propylaminocarbonyl group, a butylaminocarbonyl group, a methylaminocarbonyl group, a propyl ... 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, or ethylaminocarbonyl group, etc. Preferred are methoxy, ethoxy, methylthio, and ethylthio groups, and more preferred are methoxy and ethoxy groups.

[0043] 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.

[0044] Specific examples of preferred compounds represented by formula (i) are shown below.

[0045] Among the above, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutyramide, and Compounds represented by formula (i) are preferably 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutyramide.

[0046] These solvents can be used alone or in combination of two or more. Among these solvents, those having a boiling point of 160°C or higher are preferred, such as 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). In particular, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutyramide are preferred.

[0047] [Crosslinking Agent Component] The resist underlayer film-forming composition of the present invention may contain a crosslinking agent component. Examples of the crosslinking agent include melamine-based crosslinkers, substituted urea-based crosslinkers, and polymers thereof. A crosslinking agent having at least two crosslink-forming substituents is preferred, such as a 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.

[0048] In addition, a crosslinking agent having high heat resistance can be used as the crosslinking agent, and 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 as the crosslinking agent having high heat resistance.

[0049] The compound may be a compound represented by the following formula (5) or a condensation product of at least one compound represented by the formula (5), or a polymer or oligomer having a repeating unit represented by the following formula (6). The benzene rings in the above formulas (5) and (6) may be substituted with an alkyl group having 1 to 10 carbon atoms. １１ , R １２ , R１３ , and R １４ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the above-mentioned examples of these alkyl groups 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 number of 2 to 100 or 2 to 50 can be used.

[0050] Examples of the compound of formula (5) or a condensation product comprising at least one compound represented by formula (5) are shown below.

[0051] 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 (5-24) 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 %, preferably 0.01 to 50 mass %, and more preferably 0.05 to 40 mass %, based on the total solids content. These crosslinking agents may undergo a crosslinking reaction by self-condensation, but when crosslinkable substituents are present in the above polymer of the present invention, they can undergo a crosslinking reaction with those crosslinkable substituents.

[0052] [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, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid. A single acid may be used, or two or more acids may be used in combination. The amount of the acid and / or acid generator is typically 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 solids content.

[0053] Examples of the acid generator include thermal acid generators and photoacid generators, such as 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.

[0054] The photoacid generator generates acid when the resist is exposed to light. This allows the acidity of the underlayer film to be adjusted. This is one method for matching the acidity of the underlayer film to that of the upper layer resist. Furthermore, adjusting the acidity of the underlayer film allows the pattern shape of the resist formed in the upper layer to be adjusted. Examples of photoacid generators contained in the resist underlayer film-forming composition of the present invention include onium salt compounds, sulfonimide compounds, and disulfonyldiazomethane compounds.

[0055] 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.

[0056] Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0057] Examples of the disulfonyldiazomethane compound include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0058] The acid generator may be used alone or in combination of two or more thereof. When an acid generator is used, the proportion thereof is 0.01 to 5 parts by mass, or 0.1 to 3 parts by mass, or 0.5 to 1 part by mass, relative to 100 parts by mass of the solid content of the resist underlayer film-forming composition.

[0059] [Other Components] The resist underlayer film-forming composition of the present invention may contain a surfactant in order to prevent pinholes, striations, etc., and further improve coatability against surface unevenness. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkyl 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; polyoxyethylene sorbitan monolaurate; polyoxyethylene sorbitan monopalmitate; polyoxyethylene sorbitan monostearate; polyoxyethylene sorbitan monooleate ... 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 EFTOP 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), Asahi Guard 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 blending amount of these surfactants is usually 2.0 mass % or less, preferably 1.0 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 mass parts, or 0.001 to 1 mass part, or 0.01 to 0.5 mass parts, based on 100 mass parts of the solid content of the resist underlayer film-forming composition.

[0060] 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.

[0061] Examples of the light absorber include commercially available light absorbers described in "Technology and Market of Industrial Dyes" (CMC Publishing) and "Dye Handbook" (edited by the Society of Organic Synthetic Chemistry), such as C.I. 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; C.I. Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72, and 73; C.I. C.I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199, and 210; C.I. Disperse Violet 43; C.I. Disperse Blue 96; C.I. Fluorescent Brightening Agent 112, 135, and 163; C.I. Solvent Orange 2 and 45; C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, and 49; C.I. Pigment Green 10; C.I. Pigment Brown 2. The light-absorbing agent is usually blended in an amount of 10% by mass or less, and preferably 5% by mass or less, based on the total solid content of the resist underlayer film-forming composition.

[0062] The rheology modifier is added mainly to improve the fluidity of the resist underlayer film-forming composition, particularly in the baking process, to improve the film thickness uniformity of the resist underlayer film and the ability of the resist underlayer film-forming composition to fill holes. 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 octyldecyl 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; and stearic acid derivatives such as n-butyl stearate and glyceryl stearate. 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.

[0063] 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 peeling of the resist 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.

[0064] 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 polymer 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.

[0065] 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.

[0066] 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, but PTFE (polytetrafluoroethylene) is preferred.

[0067] [Methods for Producing Resist Underlayer Film and Semiconductor Device] Hereinafter, methods 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.

[0068] The resist underlayer film-forming composition of the present invention is applied to 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, or 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 are appropriately selected from a baking temperature of 80°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150°C to 350°C and the baking time is 0.5 to 2 minutes. The thickness of the underlayer film formed here is, for example, 10 to 1,000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.

[0069] 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 WO 2009 / 104552 A1 can be formed by spin coating, or a Si-based inorganic material film can be formed by CVD or the like.

[0070] 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, it is possible to form a resist underlayer film 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.

[0071] 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.

[0072] 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 made from a novolak resin and a 1,2-naphthoquinone diazide sulfonic acid ester; chemically amplified photoresists made from a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate and a photoacid generator; chemically amplified photoresists made from a low molecular weight compound that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; and chemically amplified photoresists made from a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, a low molecular weight compound that decomposes in the presence of an 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 those disclosed in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0073] Next, a resist pattern is formed by irradiating the resist with light or electron beams and developing the resist. First, exposure is performed through a predetermined mask. Near ultraviolet light, far ultraviolet light, or extreme ultraviolet light (for example, EUV (wavelength 13.5 nm)) is used for the exposure. Specifically, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), and F ２ An excimer laser (wavelength 157 nm) or the like can be used. Among these, ArF excimer 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.

[0074] 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.

[0075] Next, development is carried out using a developer. For example, when a positive photoresist is used, the exposed portions of the photoresist are removed, forming a photoresist pattern. Examples of the developer include aqueous alkaline solutions such as aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, and aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine. Furthermore, surfactants and the like can also be added to these developers. Development conditions are appropriately selected from a temperature of 5° C. to 50° C. and a time of 10 to 600 seconds.

[0076] 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.

[0077] First, the inorganic underlayer film (intermediate layer) in the area where the photoresist has been removed is removed by dry etching to expose the semiconductor substrate. The dry etching of the inorganic underlayer film is performed using tetrafluoromethane (CF ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F ８ Gases such as tetrafluoromethane (CF), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride and chlorine trifluoride, chlorine, trichloroborane, and dichloroborane can be used. For dry etching of the inorganic underlayer film, it is preferable to use a halogen-based gas, and more preferably a fluorine-based gas. Examples of fluorine-based gases include tetrafluoromethane (CF), ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F８ ), trifluoromethane, and difluoromethane (CH ２ F ２ ) etc.

[0078] Thereafter, the organic underlayer film is removed using the patterned photoresist and the inorganic underlayer film as a protective film. The organic underlayer film (underlayer) is preferably removed by dry etching using an oxygen-based gas, because inorganic underlayer films containing a large amount of silicon atoms are difficult to remove by dry etching using an oxygen-based gas.

[0079] Finally, the semiconductor substrate is processed. The semiconductor substrate is preferably processed by dry etching using a fluorine-based gas. The fluorine-based gas may be, for example, tetrafluoromethane (CF ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F ８ ), trifluoromethane, and difluoromethane (CH ２ F ２ ) etc.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] The weight-average molecular weights shown in the synthesis examples below in this specification are the results of measurement by gel permeation chromatography (hereinafter abbreviated as GPC in this specification). A GPC device (HLC-8320GPC) manufactured by Tosoh Corporation was used for the measurement, and the measurement conditions were as follows: GPC column: TSKgel Super H-RC, TSKgel Super Multipore HZ-N, TSKgel Super Multipore HZ-N (manufactured by Tosoh Corporation) Column temperature: 40°C Solvent: tetrahydrofuran (Kanto Chemical, for high performance liquid chromatography) Standard sample: polystyrene (manufactured by Shodex)

[0085] Synthesis Example 1 (Synthesis of Polymer (1)) Under nitrogen, 50 g (299.03 mmol) of carbazole (manufactured by Tokyo Chemical Industry Co., Ltd.), 28.74 g (299.03 mmol) of methanesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 322.34 g of propylene glycol monomethyl ether acetate were placed in a 300 mL four-neck flask, heated to 140°C, and stirred under reflux for 3 hours. The resulting reaction mixture was added dropwise to 4500 mL of methanol (Kanto Chemical, special grade) to precipitate polymer (1-1). 15 g of the solid obtained above and 7.2 g of potassium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 109.4 g of N-methyl-2-pyrrolidone, heated to 40°C, and stirred. 7.2 g of propargyl bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise to the solution, and the mixture was stirred for 12 hours. The resulting reaction mixture was filtered and cooled to room temperature. 150 g of methyl isobutyl ketone (Tokyo Chemical Industry Co., Ltd.) was added, and the organic layer was washed five times with 50 g of purified water. The polymer was then reprecipitated in 1000 mL of hexane. The resulting precipitate was filtered and vacuum dried to obtain polymer (1). The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 4517.

[0086] Synthesis Example 2 (Synthesis of Polymer (2)) Under nitrogen, 150 g (870 mmol) of carbazole (Tokyo Chemical Industry Co., Ltd.), 38.8 g (260 mmol) of glyoxal (Tokyo Chemical Industry Co., Ltd.), 4.97 g (26 mmol) of p-toluenesulfonic acid (Tokyo Chemical Industry Co., Ltd.), and 290 g of 1,4-dioxane (Kanto Chemical, special grade) were placed in a 300 mL four-neck flask, heated to 105°C, and stirred under reflux for 11 hours. The resulting reaction mixture was added dropwise to 2000 ml of methanol (Kanto Chemical, special grade) to precipitate a polymer. The resulting precipitate was filtered and vacuum dried to obtain Polymer (2-1). 15 g of the solid obtained above and 6.5 g of potassium hydroxide (Tokyo Chemical Industry Co., Ltd.) were dissolved in 109.4 g of dimethyl sulfoxide, heated to 40°C, and stirred. To this solution, 27.81 g (229 mmol) of propargyl bromide (Tokyo Chemical Industry Co., Ltd.) was added dropwise and stirred for 12 hours. The resulting reaction mixture was filtered and cooled to room temperature, after which 150 g of cyclohexanone was added, and the organic layer was washed five times with 50 g of pure water. The organic layer was then concentrated to obtain a polymer (2) solution. The molecular weight of this polymer was measured by GPC (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 1,216.

[0087] Comparative Synthesis Example 1 (Synthesis of Polymer (3)) Under nitrogen, 50 g (299.03 mmol) of carbazole (Tokyo Chemical Industry Co., Ltd.), 28.74 g (299.03 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), and 322.34 g of propylene glycol monomethyl ether acetate were placed in a 300 mL four-neck flask, heated to 140°C, and stirred under reflux for 3 hours. The resulting reaction mixture was added dropwise to 4500 ml of methanol (Kanto Chemical, special grade) to precipitate a polymer. The resulting precipitate was filtered and vacuum dried 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 3404. The resulting polymer was diluted with propylene glycol monomethyl ether acetate to a solids concentration of 14.97%, yielding a polymer (3) solution.

[0088] Comparative Synthesis Example 2 (Synthesis of Polymer (4)) Under nitrogen, 30 g (154 mmol) of ethyl carbazole (Tokyo Chemical Industry Co., Ltd.), 7.38 g (77 mmol) of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.), and 87.2 g of propylene glycol monomethyl ether acetate were placed in a 300 mL four-neck flask, heated to 140°C, and stirred under reflux for 15 hours. The resulting reaction mixture was added dropwise to 900 mL of methanol (Kanto Chemical, special grade) to precipitate a polymer. The resulting precipitate was filtered and vacuum dried 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 2662. The resulting polymer was diluted with propylene glycol monomethyl ether acetate to a solids concentration of 30%, and cation exchange resin and anion exchange resin in amounts equal to the solids amount were added, followed by stirring for 4 hours. The ion exchange resin was filtered to obtain a polymer (4) solution.

[0089] Example 1 11.99 g of the resin solution of polymer (1) obtained in Synthesis Example 1 was mixed with 1.63 g of propylene glycol monomethyl ether containing 2% TAG2689 (thermal acid generator, manufactured by King Chemical Industries, Ltd.), 0.33 g of TMOM-BP (crosslinking agent, manufactured by Honshu Chemical Industry Co., Ltd.), 0.16 g of propylene glycol monomethyl ether acetate containing 1% of a surfactant (product name: Megafac R-40, fluorine-based surfactant, manufactured by DIC Corporation), and 2.08 g of propylene glycol monomethyl ether acetate. The mixture was then filtered through a polytetrafluoroethylene microfilter having a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0090] Example 2 0.27 g of propylene glycol monomethyl ether containing 2% pyridinium p-hydroxybenzenesulfonate, 0.12 g of TMOM-BP (a crosslinking agent manufactured by Honshu Chemical Industry Co., Ltd.), 3.64 g of propylene glycol monomethyl ether acetate containing 1% of a surfactant (a fluorine-based surfactant, trade name: Megafac R-40 manufactured by DIC Corporation), 1.59 g of propylene glycol monomethyl ether, and 0.21 g of cyclohexanone were mixed with 4.1 g of the resin solution of polymer (2) obtained in Synthesis Example 2. The mixture was then filtered through a polytetrafluoroethylene microfilter having a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0091] Comparative Example 1 1.11 g of propylene glycol monomethyl ether containing 2% pyridinium p-hydroxybenzenesulfonate, 0.22 g of tetramethoxymethyl glycoluril, 0.11 g of propylene glycol monomethyl ether acetate containing 1% of a surfactant (manufactured by DIC Corporation, product name: Megafac [product name] R-40, fluorine-based surfactant), 5.89 g of propylene glycol monomethyl ether acetate, and 3.01 g of propylene glycol monomethyl ether were mixed with 4.65 g of the resin solution of polymer (3) obtained in Comparative Synthesis Example 1. The mixture was then filtered through a polytetrafluoroethylene microfilter having a pore size of 0.1 μm to prepare a solution of a resist underlayer film-forming composition.

[0092] Comparative Example 2 2.51 g of the resin solution of polymer (4) obtained in Comparative Synthesis Example 2 was mixed with 0.60 g of propylene glycol monomethyl ether containing 2% TAG2689 (thermal acid generator, manufactured by King Chemical Industry Co., Ltd.), 0.18 g of TMOM-BP (crosslinking agent, manufactured by Honshu Chemical Industry Co., Ltd.), 0.06 g of propylene glycol monomethyl ether acetate containing 1% of a surfactant (fluorosurfactant, trade name: Megafac R-40, manufactured by DIC Corporation), 4.47 g of propylene glycol monomethyl ether acetate, and 2.17 g of propylene glycol monomethyl ether. The mixture was then filtered through a 0.1 μm diameter polytetrafluoroethylene microfilter to prepare a solution of a resist underlayer film-forming composition.

[0093] [Elution Test in Photoresist Solvent] Each of the resist underlayer film-forming compositions prepared in Example 1 to Comparative Example 2 was applied to a silicon wafer using a spinner. The composition was then baked on a hot plate at 240°C 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), which is the solvent used in photoresist solutions, to confirm their insolubility in the solvent. The results are indicated by "○" in Table 1 below.

[0094] [Optical Parameter Test] Each of the resist underlayer film-forming compositions prepared in Example 1 to Comparative Example 2 was applied onto a silicon wafer using a spinner. The composition was then baked on a hot plate at 240°C for 1 minute to form a resist underlayer film (film thickness: 0.2 µm). The refractive index (n value) and extinction coefficient (k value) of each of these resist underlayer films at a wavelength of 193 nm were measured using an optical ellipsometer (VUV-VASE VU-302, manufactured by J.A. Woollam Co.). The results are shown in Table 1 below. In order for the resist underlayer film to have sufficient antireflection function, it is desirable that the n value at a wavelength of 193 nm be 1.40 or more and 1.65 or less, and the k value be 0.1 or more and 0.45 or less.

[0095] [Bending Resistance Evaluation] Each resist underlayer film-forming composition solution prepared in Example 1 to Comparative Example 2 was applied to a silicon wafer coated with a silicon oxide film using a spin coater. The wafer was baked on a hot plate at 240°C for 60 seconds to form a resist underlayer film (200 nm thick). A silicon hard mask-forming composition solution was applied to the resist underlayer film and baked at 240°C for 1 minute to form a silicon hard mask layer (30 nm thick). A resist solution was applied thereon and baked at 100°C for 1 minute to form a resist layer (150 nm thick). The wafer was exposed to light at a wavelength of 193 nm using a mask, post-exposure baking (PEB) was performed (105°C for 1 minute), and then developed to obtain a resist pattern. Subsequently, dry etching was performed using a fluorine-based gas and an oxygen-based gas. The resist pattern was transferred to a silicon wafer coated with a silicon oxide film, and the shape of each pattern was observed using a CG-4100 (manufactured by Hitachi High-Technologies Corporation).

[0096] When a resist pattern is formed on a substrate to be processed through a lithography process and an etching process, irregular pattern bending is more likely to occur as the width of the formed pattern narrows. Specifically, this occurs when a resist underlayer film used as a mask material when etching the target substrate to be processed, particularly a pattern formed from an organic resin layer, bends left and right. This phenomenon makes it difficult to faithfully process the substrate. Therefore, the less bending occurs, the more precise the substrate processing becomes. The results are shown in the table. Samples in which pattern bending was visible when the resist pattern was 40 nm were marked with an X, and samples in which bending occurred at sizes smaller than 40 nm were marked with an O. Examples 1 and 2 had high bending resistance, while Comparative Examples 1 and 2 had low bending resistance.

[0097]

Claims

1. A resist underlayer film forming composition comprising a polymer having at least one repeating unit represented by the following formula (1), formula (2), formula (3) or formula (4), and a solvent: (In formulas (1) to (4), Ar １ , Ar ２ are each independently R １ , R ２ represents a benzene ring or a naphthalene ring which may be substituted by R １ and R ２ R each represents a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a combination thereof which may contain an ether bond, a ketone bond, or an ester bond. ３ is a tetravalent organic group having 1 to 2 carbon atoms; R ４ is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an alkynyl group having 2 to 3 carbon atoms. １ and n ２ are Ar １ , Ar ２ is an integer of 1 to 3 when Ar is a benzene ring; １ , Ar ２ is an integer of 1 to 5 when R is a naphthalene ring. ５ represents an alkyl group having 2 to 10 carbon atoms. In formulas (3) and (4), X represents a single bond, a saturated or unsaturated linear or cyclic organic group having 1 to 30 carbon atoms which may contain a nitrogen atom, or an arylene group having 6 to 30 carbon atoms.

2. In formula (1) to formula (4), Ar １ and Ar ２ The resist underlayer film forming composition according to claim 1, wherein is a benzene ring.

3. In formulas (1) to (4), R １ , R ２ The resist underlayer film forming composition according to claim 1 or 2, wherein each of the formulas is a hydrogen atom.

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

5. The resist underlayer film forming composition according to any one of claims 1 to 4, further comprising an acid and / or an acid generator.

6. A resist underlayer film forming composition according to any one of claims 1 to 5, 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 made of the resist underlayer film forming composition according to any one of claims 1 to 6.

8. A method for manufacturing a semiconductor device, comprising: 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; forming a resist pattern by irradiating the formed resist film with light or an electron beam and developing it; etching and patterning the resist underlayer film through the formed resist pattern; and processing a semiconductor substrate through the patterned resist underlayer film.