Method for producing polymer

Abstract

To provide a novel method for producing a polymer that, in production of a polymer through reaction of a monomer containing a pyrimidinetrione structure, an imidazolidinedione structure, or a triazinetrione structure, enables removal of a low-molecular-weight component and allows reproducible creation of a polymer having a desired weight-average molecular weight and a low polydispersity.SOLUTION: A method for producing a polymer includes a first step of synthesizing a crude polymer by reacting a monomer containing a pyrimidinetrione structure, an imidazolidinedione structure, or a triazinetrione structure in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt, and a second step of precipitating and filtering a purified polymer by mixing a solution containing the crude polymer obtained in the first step with a poor solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polymer, and more specifically to a method for producing a condensation polymer, which comprises reacting a monomer having a pyrimidinetrione structure, an imidazolinedinedione structure, or a triazinetrione structure, and purifying the resulting polymer by reprecipitation. [Background technology]

[0002] Conventionally, a method for producing the condensation polymer involves reacting monoallyldiglycidylisocyanuric acid with 5,5-diethylbarbituric acid. For example, Patent Documents 1 and 2 disclose Synthesis Example 1 in which the above compounds and benzyltriethylammonium chloride are dissolved in propylene glycol monomethyl ether, and then reacted at 130°C for 24 hours to obtain a solution containing a polymer having a weight-average molecular weight of 6,800.

[0003] Patent Documents 1 and 2 further describe that an antireflective film-forming composition or a resist underlayer film-forming composition for EUV lithography was prepared using a solution containing the obtained polymer.

[0004] Polymers obtained by chemical synthesis are usually aggregates of molecules with different molecular weights (degrees of polymerization), and the molecular weight of such polymers is expressed as an average molecular weight such as weight-average molecular weight Mw or number-average molecular weight Mn. Therefore, the greater the content of low-molecular-weight components in a polymer, the lower the average molecular weight of the polymer and the greater the polydispersity (Mw / Mn) of the polymer.

[0005] However, the polymers obtained by the synthesis methods described in Patent Documents 1 and 2 contain a large amount of low-molecular-weight components, and therefore, when an antireflective coating-forming composition or a resist underlayer coating-forming composition for EUV lithography prepared using the polymer is applied to a substrate and baked to form a film, a problem arises in that a large amount of sublimates derived from the low-molecular-weight components are generated. These sublimates cause contamination of the inside of the baking apparatus, specifically the top plate directly above the heating plate on which the substrate is placed, and the inside of the exhaust duct. When the inside of the baking apparatus becomes contaminated by sublimates, the inside of the apparatus must be cleaned each time. Therefore, from the perspective of improving productivity, there is a strong demand for reducing the amount of sublimates generated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2005 / 098542 [Patent Document 2] International Publication No. 2013 / 018802 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and aims to provide a novel production method that can remove low-molecular-weight components that cause the formation of sublimates in the production of polymers by reacting monomers containing a pyrimidinetrione structure, an imidazolinedinedione structure, or a triazinetrione structure, and that can reproducibly produce polymers having a target weight-average molecular weight and a small polydispersity index. [Means for solving the problem]

[0008] As a result of extensive research aimed at solving the above problems, the present inventors have found that a polymer having a target weight-average molecular weight and a small polydispersity index can be reproducibly obtained by synthesizing a crude polymer by reacting a monomer having a pyrimidinetrione structure, an imidazolinedinedione structure, or a triazinetrione structure, and then reprecipitating the crude polymer from a solution containing the crude polymer, thereby completing the present invention.

[0009] That is, the present invention provides the following method for producing a polymer. 1. A first step of reacting a monomer represented by the following formula (a) with a monomer represented by the following formula (b) in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt to synthesize a crude polymer having a repeating unit represented by the following formula (1); a second step of mixing the solution containing the crude polymer obtained in the first step with a poor solvent to precipitate a purified polymer having a repeating unit represented by formula (1), and filtering the precipitate. [ka] In formula (1) and formula (a), A's each independently represent a hydrogen atom, a methyl group, or an ethyl group; in formula (1), formula (a), and formula (b), Q 1 and Q 2 is expressed by equation (2) or equation (3): [ka] [In the formula, Q 3represents an alkylene group having 1 to 10 carbon atoms, which may contain a sulfide bond or a disulfide bond, an alkenylene group having 2 to 10 carbon atoms, a phenylene group, a naphthylene group, or an anthrylene group, and the phenylene group, naphthylene group, and anthrylene group may each independently be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; each B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms; each n independently represents 0 or 1; each m independently represents 0 or 1; and X is a group represented by formula (4), formula (5), or formula (6): [ka] (In the formula, R 1 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the alkyl and alkenyl groups may be substituted with a halogen atom, a hydroxy group, or a cyano group; the benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxy group; the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; 1 may be bonded to each other to form a ring having 3 to 6 carbon atoms; R 2 represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms.) where Q 1 and Q 2 At least one of the groups contains a structure represented by formula (3). 2. The method for producing a polymer according to 1, wherein the organic solvent used in the first step is one or more selected from the group consisting of benzene, toluene, xylene, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, and N-methylpyrrolidone. 3. The method for producing a polymer according to claim 2, wherein the organic solvent is propylene glycol monomethyl ether. 4. The method for producing a polymer according to any one of 1 to 3, wherein the poor solvent used in the second step is one or more solvents selected from the group consisting of diethyl ether, cyclopentyl methyl ether, diisopropyl ether and isopropyl alcohol. 5. The method for producing a polymer according to 4, wherein the poor solvent is isopropyl alcohol. 6. A method for producing a polymer according to any one of 1 to 5, wherein low-molecular-weight components having a weight-average molecular weight of 1,000 or less are removed from the crude polymer by the second step. 7. The method for producing a polymer according to any one of 1 to 6, wherein 30% by mass or more of the low-molecular-weight components contained in the crude polymer are removed by the second step. 8. A method for producing a composition for forming a resist underlayer film, comprising mixing a polymer obtained by any one of the production methods 1 to 7 with an organic solvent. [Effects of the Invention]

[0010] According to the method for producing a polymer of the present invention, low-molecular-weight components such as oligomers having a weight-average molecular weight of 1,000 or less can be removed, and therefore, polymers having a relatively high weight-average molecular weight and a small polydispersity can be produced with good reproducibility. Furthermore, a composition for forming a resist underlayer film produced using the polymer obtained by the production method of the present invention suppresses the generation of sublimates during film formation, thereby reducing the frequency of cleaning the inside of the apparatus and contributing to improving the productivity of the resist underlayer film. DETAILED DESCRIPTION OF THE INVENTION

[0011] Each step of the method for producing a polymer according to the present invention will now be described in more detail. In the following description, the crude polymer refers to the polymer synthesized in the first step described below, and the purified polymer refers to the polymer obtained from the solution containing the crude polymer through the second step described below.

[0012] In the present invention, the low-molecular-weight component refers to a component such as an oligomer having a weight-average molecular weight (hereinafter referred to as Mw) of 1,000 or less, which means a polymer having a repeating unit represented by formula (1), such as an oligomer, whose Mw does not exceed 1,000, and does not include unreacted monomer components or other components such as the catalyst used in the reaction. In addition, in the present invention, Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0013] <1st process> The first step is a step of reacting a monomer represented by the following formula (a) (hereinafter sometimes abbreviated as component (a)) with a monomer represented by the following formula (b) (hereinafter sometimes abbreviated as component (b)) in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt to synthesize a crude polymer having a repeating unit represented by the following formula (1):

[0014] [ka]

[0015] In formula (1) and formula (a), A's each independently represent a hydrogen atom, a methyl group, or an ethyl group. In formula (1), formula (a), and formula (b), Q 1 and Q 2 represents formula (2) or formula (3).

[0016] [ka]

[0017] In formula (2), Q3 represents an alkylene group having 1 to 10 carbon atoms, which may contain a sulfide bond or a disulfide bond, an alkenylene group having 2 to 10 carbon atoms, a phenylene group, a naphthylene group, or an anthrylene group, and the phenylene group, naphthylene group, and anthrylene group may each independently be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms. In formula (3), each B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms. Each n independently represents 0 or 1. Each m independently represents 0 or 1. X represents formula (4), formula (5), or formula (6).

[0018] [ka]

[0019] In formula (4) and formula (5), R 1 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the alkyl and alkenyl groups may be substituted with a halogen atom, a hydroxy group, or a cyano group; the benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxy group; the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; 1 may be bonded to each other to form a ring having 3 to 6 carbon atoms. 2 represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms.

[0020] However, Q 1 and Q 2 At least one of them contains a structure represented by formula (3).

[0021] The alkylene group having 1 to 10 carbon atoms may be linear, branched, or cyclic, and examples thereof include methylene, ethylene, propylene, pentamethylene, cyclohexylene, 2-methylpropylene, and 1-methylethylidene. Furthermore, the alkylene group having 1 to 10 carbon atoms and containing a sulfide bond or a disulfide bond includes alkylene groups containing a sulfide bond or a disulfide bond represented by the following formula:

[0022] [ka] (In the formula, * represents a bond.)

[0023] The alkenylene group having 2 to 10 carbon atoms may be linear, branched, or cyclic, and examples thereof include ethenylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octenylene, and nonenylene groups.

[0024] The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, neopentyl, n-hexyl, cyclopentyl, and cyclohexyl groups.

[0025] The alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and examples thereof include methoxy, ethoxy, i-propoxy, n-pentyloxy, n-hexyloxy, and cyclohexyloxy groups.

[0026] The alkylthio group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and examples thereof include methylthio, ethylthio, i-propylthio, n-pentylthio, and cyclohexylthio groups.

[0027] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0028] The Two R's 1 Examples of the ring having 3 to 6 carbon atoms formed by bonding include a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring.

[0029] Specific examples of component (a) include the following: Q 1 Examples of compounds in which is a group represented by formula (2) include diglycidyl ester compounds and diglycidyl ether compounds.

[0030] Examples of the diglycidyl ester compound include terephthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, phthalic acid diglycidyl ester, 2,5-dimethylterephthalic acid diglycidyl ester, 2,5-diethylterephthalic acid diglycidyl ester, 2,3,5,6-tetrachloroterephthalic acid diglycidyl ester, 2,3,5,6-tetrabromoterephthalic acid diglycidyl ester, 2-nitroterephthalic acid diglycidyl ester, and 2,3,5,6-tetrafluoroterephthalic acid diglycidyl ester. Oroterephthalic acid diglycidyl ester, 2,5-dihydroxyterephthalic acid diglycidyl ester, 2,6-dimethylterephthalic acid diglycidyl ester, 2,5-dichloroterephthalic acid diglycidyl ester, 2,3-dichloroisophthalic acid diglycidyl ester, 3-nitroisophthalic acid diglycidyl ester, 2-bromoisophthalic acid diglycidyl ester, 2-hydroxyisophthalic acid diglycidyl ester, 3-hydroxyisophthalic acid diglycidyl ester, 2-methoxy Isophthalic acid diglycidyl ester, 5-phenylisophthalic acid diglycidyl ester, 3-nitrophthalic acid diglycidyl ester, 3,4,5,6-tetrachlorophthalic acid diglycidyl ester, 4,5-dichlorophthalic acid diglycidyl ester, 4-hydroxyphthalic acid diglycidyl ester, 4-nitrophthalic acid diglycidyl ester, 4-methylphthalic acid diglycidyl ester, 3,4,5,6-tetrafluorophthalic acid diglycidyl ester, 2,6-naphthalenedicarboxylic acid acid diglycidyl ester, 1,2-naphthalenedicarboxylic acid diglycidyl ester, 1,4-naphthalenedicarboxylic acid diglycidyl ester, 1,8-naphthalenedicarboxylic acid diglycidyl ester, anthracene-9,10-dicarboxylic acid diglycidyl ester, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, dithiodiglycolic acid diglycidyl ester, 2,2'-thiodiglycolic acid diglycidyl ester and diglycolic acid diglycidyl ester.

[0031] Examples of diglycidyl ether compounds include ethylene glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-benzenediol diglycidyl ether, 1,3-benzenediol diglycidyl ether, 1,4-benzenediol diglycidyl ether, and 1,6-naphthalenediol diglycidyl ether.

[0032] Q 1 Examples of the compound in which the group represented by formula (3) is a diglycidyl hydantoin compound, a diglycidyl barbituric acid compound, and a diglycidyl isocyanuric acid compound are mentioned.

[0033] Examples of diglycidylhydantoin compounds include 1,3-diglycidylhydantoin, 1,3-diglycidyl-5,5-diphenylhydantoin, 1,3-diglycidyl-5,5-dimethylhydantoin, 1,3-diglycidyl-5-methylhydantoin, 1,3-diglycidyl-5-ethyl-5-phenylhydantoin, 1,3-diglycidyl-5-benzylhydantoin, 1,3-diglycidyl-5-hydantoin acetic acid, and 1,3-diglycidyl-5-ethyl-5-methylhydantoin. 1,3-diglycidyl-5-methylhydantoin, 1,3-diglycidyl-5,5-tetramethylenehydantoin, 1,3-diglycidyl-5,5-pentamethylenehydantoin, 1,3-diglycidyl-5-(4-hydroxybenzyl)hydantoin, 1,3-diglycidyl-5-phenylhydantoin, 1,3-diglycidyl-5-hydroxymethyl-hydantoin, and 1,3-diglycidyl-5-(2-cyanoethyl)hydantoin.

[0034] Examples of diglycidyl barbituric acid compounds include 1,3-diglycidyl-5,5-diethylbarbituric acid, 1,3-diglycidyl-5-phenyl-5-ethylbarbituric acid, 1,3-diglycidyl-5-ethyl-5-isoamylbarbituric acid, 1,3-diglycidyl-5-allyl-5-isobutylbarbituric acid, 1,3-diglycidyl-5-allyl-5-isopropylbarbituric acid, 1,3-diglycidyl-5-β-bromoallyl-5-sec-butyl ... Examples include glycidyl-5-ethyl-5-(1-methyl-1-butenyl)barbituric acid, 1,3-diglycidyl-5-isopropyl-5-β-bromoallyl barbituric acid, 1,3-diglycidyl-5-(1-cyclohexyl)-5-ethylmalonyl urea, 1,3-diglycidyl-5-ethyl-5-(1-methylbutyl)malonyl urea, 1,3-diglycidyl-5,5-diallylmalonyl urea diglycidyl, and 1,3-diglycidyl-5-ethyl-5-normal butyl barbituric acid.

[0035] Examples of diglycidyl isocyanuric acid compounds include monoallyl diglycidyl isocyanuric acid, monomethyl diglycidyl isocyanuric acid, monoethyl diglycidyl isocyanuric acid, monopropyl diglycidyl isocyanuric acid, monomethylthiomethyl diglycidyl isocyanuric acid, monoisopropyl diglycidyl isocyanuric acid, monomethoxymethyl diglycidyl isocyanuric acid, monobutyl diglycidyl isocyanuric acid, monomethoxyethoxymethyl diglycidyl isocyanuric acid, monophenyl diglycidyl isocyanuric acid, and monobromodiglycidyl isocyanuric acid, monoallyl isocyanuric acid diglycidyl ester, monomethyl isocyanuric acid diglycidyl ester, and the like.

[0036] Specific examples of component (b) include the following: Q 2 However, examples of compounds having the group represented by formula (2) include dicarboxylic acid compounds.

[0037] Examples of dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 2,5-diethylterephthalic acid, 2,3,5,6-tetrachloroterephthalic acid, 2,3,5,6-tetrabromoterephthalic acid, 2-nitroterephthalic acid, 2,3,5,6-tetrafluoroterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dimethylterephthalic acid, 2,5-dichloroterephthalic acid, 2,3-dichloroisophthalic acid, 3-nitroisophthalic acid, 2-bromoisophthalic acid, 2-hydroxyisophthalic acid, 3-hydroxyisophthalic acid, 2-methoxyisophthalic acid, 5-phenylisophthalic acid, 3-nitrophthalic acid, 3,4,5,6-tetrachlorophthalic acid, and 4,5-dichloroisophthalic acid. Examples of suitable phthalic acid include phthalic acid, 4-hydroxyphthalic acid, 4-nitrophthalic acid, 4-methylphthalic acid, 3,4,5,6-tetrafluorophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,2-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, anthracene-9,10-dicarboxylic acid, ethylene glycol, 1,3-propanedicarboxylic acid, 4-hydroxybenzoic acid, fumaric acid, dithiodiglycolic acid, 2,2'-thiodiglycolic acid, tartaric acid, malonic acid, succinic acid, glutaric acid, adipic acid, itaconic acid, 3,3'-(5-methyl-2,4,6-trioxo-1,3,5-triazine-1,3-diyldipropionic acid, and 3,3'-dithiodipropionic acid.

[0038] Q 2 Examples of compounds in which is a group represented by formula (3) include hydantoin compounds, barbituric acid compounds and isocyanuric acid compounds.

[0039] Examples of hydantoin compounds include hydantoin, 5,5-diphenylhydantoin, 5,5-dimethylhydantoin, 5-ethylhydantoin, 5-benzylhydantoin, 5-ethyl-5-phenylhydantoin, 5-methylhydantoin, 5,5-tetramethylenehydantoin, 5,5-pentamethylenehydantoin, 5-(4-hydroxybenzyl)-hydantoin, 5-phenylhydantoin, 5-hydroxymethylhydantoin, and 5-(2-cyanoethyl)hydantoin.

[0040] Examples of barbituric acid compounds include barbituric acid, 5,5-dimethylbarbituric acid, 5,5-diethylbarbituric acid (also known as barbital), 5-methyl-5-ethylbarbituric acid, 5,5-diallylbarbituric acid (also known as allobarbital), 5-ethyl-5-phenylbarbituric acid (also known as phenobarbital), 5-ethyl-5-isopentylbarbituric acid (also known as amobarbital), 5,5-diallylmalonylurea, 5-ethyl-5-isoamylbarbituric acid, and 5-allyl-5-isobutyric acid. arylbarbituric acid, 5-allyl-5-isopropylbarbituric acid, 5-β-bromoallyl-5-sec-butylbarbituric acid, 5-ethyl-5-(1-methyl-1-butenyl)barbituric acid, 5-isopropyl-5-β-bromoallylbarbituric acid, 5-(1-cyclohexyl)-5-ethylmalonylurea, 5-ethyl-5-(1-methylbutyl)malonylurea, 5,5-dibromobarbituric acid, 5-phenyl-5-ethylbarbituric acid, and 5-ethyl-5-normal-butylbarbituric acid.

[0041] Examples of the isocyanuric acid compound include monoallyl isocyanuric acid, monomethyl isocyanuric acid, monoethyl isocyanuric acid, monopropyl isocyanuric acid, monoisopropyl isocyanuric acid, monophenyl isocyanuric acid, monobenzyl isocyanuric acid, and monochloroisocyanuric acid.

[0042] The above-exemplified components (a) and (b) can usually be combined by selecting one compound from each, but this is not limited thereto, and multiple compounds may be selected and used for either or both of components (a) and (b), provided that at least one of components (a) and (b) contains a compound having a skeleton selected from hydantoin, barbituric acid, and isocyanuric acid.

[0043] Examples of the component (a) that can be suitably used in the production method of the present invention include, but are not limited to, the following compounds.

[0044] [ka]

[0045] Furthermore, examples of the component (b) that can be suitably used in the production method of the present invention include, but are not limited to, the following compounds.

[0046] [ka]

[0047] The blending ratio (molar ratio) of component (a) and component (b) is not particularly limited, but from the viewpoint of suppressing the remaining unreacted epoxy group-containing component (a), it is preferable that component (a) and component (b) are equimolar or that component (b) is in excess relative to component (a), and more preferably (a):(b) = 1:1.21 to 1:1. By keeping the blending ratio at or below the upper limit, it becomes easier to obtain a polymer having the desired Mw.

[0048] As the quaternary phosphonium salt, for example, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, hexyltriphenylphosphonium bromide, tetrabutylphosphonium bromide, benzyltriphenylphosphonium bromide, methyltriphenylphosphonium chloride, ethyltriphenylphosphonium chloride, butyltriphenylphosphonium chloride, hexyltriphenylphosphonium chloride, tetrabutylphosphonium chloride, benzyltriphenylphosphonium chloride, methyltriphenylphosphonium iodide, ethyltriphenylphosphonium iodide, butyltriphenylphosphonium iodide, hexyltriphenylphosphonium iodide, tetrabutylphosphonium iodide and benzyltriphenylphosphonium iodide can be enumerated.In the present invention, ethyltriphenylphosphonium bromide and tetrabutylphosphonium bromide can be suitably used.

[0049] Examples of quaternary ammonium salts include tetramethylammonium fluoride, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium nitrate, tetramethylammonium sulfate, tetramethylammonium acetate, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium fluoride, tetrabutylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium chloride, phenyltrimethylammonium chloride, benzyltriethylammonium chloride, methyltributylammonium chloride, benzyltributylammonium chloride, methyltrioctylammonium chloride, etc. In the present invention, benzyltriethylammonium chloride can be preferably used.

[0050] The amount of the quaternary phosphonium salt and quaternary ammonium salt to be added is not particularly limited as long as it is an amount that allows the reaction to proceed, but is preferably 0.1 to 10.0%, and more preferably 1.0 to 5.0%, based on the number of moles of component (a).

[0051] The organic solvent used in the first step may be any solvent that does not affect the reaction, such as benzene, toluene, xylene, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, and N-methylpyrrolidone. These may be used alone or in combination of two or more. In the present invention, propylene glycol monomethyl ether is preferred, taking into consideration the intended use of the composition using the final polymer obtained.

[0052] The amount of organic solvent used is not particularly limited and can be appropriately determined depending on the type and amount of each of the above components. In the present invention, in consideration of efficiently progressing the reaction, the total solid content of the above components is preferably 5 to 40 mass%, more preferably 10 to 30 mass%, and even more preferably 15 to 25 mass%. In the present invention, the solid content refers to the components other than the solvent that constitute the solution.

[0053] The reaction temperature in the first step is usually 200°C or lower, and considering the boiling point of the organic solvent used, it is preferably 150°C or lower, more preferably 130°C or lower. There are no particular restrictions on the lower limit of the reaction temperature, but considering the need to quickly complete the condensation reaction of components (a) and (b), it is preferably 50°C or higher, more preferably 60°C or higher. Reflux may be performed during heating.

[0054] The reaction time cannot be generally determined because it depends on the reaction temperature and the reactivity of the raw materials, but it is usually about 1 to 48 hours, and when the reaction temperature is 60 to 130°C, it is generally about 15 to 30 hours.

[0055] Examples of the repeating unit represented by formula (1) include, but are not limited to, those represented by the following formulae (1-1) to (1-5), in which Me is a methyl group.

[0056] [ka]

[0057] <Second process> The second step is a step of mixing the solution containing the crude polymer obtained in the first step (hereinafter referred to as the crude polymer solution) with a poor solvent to precipitate a crude polymer having a repeating unit represented by formula (1), followed by filtration. This second step allows the removal of low-molecular-weight components contained in the crude polymer. Here, the crude polymer solution may be the reaction solution obtained in the first step as is, or may be a solution obtained by dissolving the crude polymer isolated by an appropriate means such as drying in an appropriate solvent. In the latter case, the organic solvent used in the first step may be used as the solvent.

[0058] The poor solvent used in the second step can be a solvent in which the polymer has low solubility and in which low-molecular-weight components are soluble, such as diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropyl alcohol. These can be used alone or in combination of two or more. In the present invention, isopropyl alcohol can be preferably used.

[0059] In the present invention, when the crude polymer solution and the poor solvent are mixed, the order of mixing is not particularly limited, and the crude polymer solution may be added to the poor solvent, or the poor solvent may be added to the crude polymer solution. However, in consideration of removing as many low-molecular-weight components as possible, the method of adding the crude polymer solution to the poor solvent is preferred.

[0060] When mixing the two, they may be added gradually by dropwise addition or the entire amount may be added all at once. However, in consideration of reducing the content of low molecular weight components in the purified polymer, the method of adding them gradually by dropwise addition is preferred.

[0061] The amount of the poor solvent used relative to the crude polymer solution is not particularly limited as long as it is an amount that does not cause precipitation of low-molecular-weight components and can sufficiently precipitate the polymer, but is preferably 2 to 30 times by mass, more preferably 5 to 20 times by mass, and even more preferably 5 to 15 times by mass relative to the total mass of the crude polymer solution.

[0062] The temperature during mixing may be set appropriately within the range from the melting point of the solvent used to the boiling point of the solvent, and is not particularly limited, but can usually be set to about -20 to 50°C. In consideration of the ease of precipitation and workability, the temperature is preferably 0 to 50°C, and more preferably 0 to 30°C.

[0063] A preferred embodiment of the above mixing operation is, for example, when a crude polymer solution having a total solids concentration of 5 to 50% by mass is gradually added to a poor solvent having a mass ratio of 5 to 20 times that of the crude polymer solution, by gradually adding the poor solvent over a period of 15 minutes to 1 hour per 50 g of the crude polymer solution, but is not limited thereto.

[0064] After the mixing operation is completed, stirring may be continued for a predetermined time to remove as much of the low molecular weight components as possible. In this case, the stirring time is preferably 10 minutes to 2 hours, more preferably 15 minutes to 1 hour.

[0065] In order to further reduce the polydispersity of the polymer, a step may be carried out in which the precipitate separated by filtration in the second step is dissolved again in the organic solvent used in the first step, the resulting solution is mixed with the poor solvent, and the resulting precipitate is separated by filtration.

[0066] The Mw of the purified polymer obtained by the production method of the present invention is generally 1,000 to 200,000, preferably 3,000 to 100,000, more preferably 4,000 to 47,000, even more preferably 7,000 to 47,000, and still more preferably 7,000 to 27,000.

[0067] The second step can remove 30% by mass or more, preferably 40% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more of the low molecular weight components contained in the crude polymer.

[0068] According to the present invention, a composition for forming a resist underlayer film can be produced by mixing the purified polymer obtained through the above steps with an organic solvent. The composition for forming a resist underlayer film may contain additives such as a crosslinking agent, an acid catalyst (organic acid) that promotes the crosslinking reaction, a surfactant, a light absorber, a rheology modifier, and an adhesion aid, as needed.

[0069] The organic solvent can be any organic solvent that can dissolve the solid content and form a uniform solution. In particular, since the composition for forming a resist underlayer film according to the present invention is used in the form of a uniform solution, in consideration of its coating performance, in addition to the organic solvents exemplified as usable in the first step, solvents that are generally used in lithography steps can be used in combination.

[0070] Examples of the organic solvent include 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 monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. , cycloheptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These organic solvents may be used alone or in combination of two or more.

[0071] The solids concentration of the composition for forming a resist underlayer film of the present invention is appropriately set taking into consideration the viscosity and surface tension of the composition, the thickness of the thin film to be formed, etc., but is usually about 0.1 to 20.0 mass%, preferably 0.5 to 15.0 mass%, and more preferably 1.0 to 10.0 mass%. Here, the solids in the solids concentration of the composition refer to components other than the solvent contained in the composition for forming a resist underlayer film of the present invention.

[0072] The crosslinking agent is not particularly limited, but compounds having at least two crosslinking groups in the molecule are suitable. Examples include melamine-based compounds and substituted urea-based compounds having crosslinking groups such as methylol groups and methoxymethyl groups. Specific examples include compounds such as methoxymethylated glycoluril or methoxymethylated melamine, such as tetramethoxymethylglycoluril, tetrabutoxymethylglycoluril, or hexamethoxymethylmelamine. Other examples include compounds such as tetramethoxymethylurea and tetrabutoxymethylurea. These crosslinking agents can undergo a crosslinking reaction by self-condensation. They can also undergo a crosslinking reaction with hydroxyl groups in a polymer having a structure represented by formula (1). This crosslinking reaction strengthens the underlayer film that is formed. Consequently, the underlayer film has low solubility in organic solvents. These crosslinking agents may be used alone or in combination.

[0073] When the composition for forming a resist underlayer film contains a crosslinking agent, its content varies depending on the organic solvent used, the base substrate used, the required solution viscosity, the required film shape, etc., but from the viewpoint of the curability of the coating film, it is preferably 0.01 to 50 mass % of the solid content, more preferably 0.1 to 40 mass %, and even more preferably 0.5 to 30 mass %. These crosslinking agents may undergo a crosslinking reaction by self-condensation, but when crosslinkable substituents are present in the polymer of the present invention, they can undergo a crosslinking reaction with the crosslinkable substituents.

[0074] Examples of the acid catalyst include sulfonic acid compounds such as p-phenolsulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, and pyridinium-p-toluenesulfonate; carboxylic acid compounds such as salicylic acid, 5-sulfosalicylic acid, citric acid, benzoic acid, and hydroxybenzoic acid; 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, 2,4-dinitrobenzyl p-trifluoromethylbenzenesulfonate, and phenyl-bis(trichloromethyl)-s-triazine. Examples of suitable acid catalysts include acid compounds that generate acid when exposed to heat or light, such as iodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, and N-hydroxysuccinimide trifluoromethanesulfonate; iodonium salt-based acid generators, such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt-based acid generators, such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium trifluoromethanesulfonate. Among these, sulfonic acid compounds and carboxylic acid compounds are preferred for use in the present invention. These acid catalysts may be used singly or in combination of two or more.

[0075] When the composition for forming a resist underlayer film contains an acid catalyst, the content thereof is preferably 0.0001 to 20 mass %, more preferably 0.01 to 15 mass %, and even more preferably 0.1 to 10 mass %, of the solid content, from the viewpoint of sufficiently promoting the crosslinking reaction.

[0076] Surfactants are added to improve the coating properties on semiconductor substrates. Examples of surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; polyoxyethylene-polyoxypropylene block copolymers; and sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate. sorbitan fatty acid esters; nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; F-Top (registered trademark) EF301, EF303, and EF352 (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac (registered trademark) F171, F173, R-30, R-30N, R-40, and R-40-LM (manufactured by DIC Corporation), Fluorad FC430, FC431 (manufactured by 3M Fluorine-based surfactants such as Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by AGC Corporation), and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants may be used alone or in combination of two or more.

[0077] When the composition for forming a resist underlayer film contains a surfactant, the content thereof is preferably 0.0001 to 10 mass %, more preferably 0.01 to 5 mass %, of the solid content, from the viewpoint of improving the coatability to the semiconductor substrate.

[0078] Examples of the light-absorbing agent include commercially available light-absorbing agents described in "Technology and Market of Industrial Dyes" (CMC Publishing) and "Handbook of Dyes" (edited by the Society of Organic Synthetic Chemistry), such as CI Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114, and 124; CI Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72, and 73; CI Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199, and 210; CI Disperse Violet 43; CI Disperse Blue 96; and CI Fluorescent Brightening. Suitable examples of the agents that can be used include Agents 112, 135, and 163; CI Solvent Orange 2 and 45; CI Solvent Red 1, 3, 8, 23, 24, 25, 27, and 49; CI Pigment Green 10; and CI Pigment Brown 2.

[0079] When the light absorbing agent is contained, the content thereof is usually preferably 0.1 to 10 mass % of the solid content, and more preferably 0.1 to 5 mass %.

[0080] 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. Examples of the rheology modifier 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.

[0081] When the composition for forming a resist underlayer film contains a rheology control agent, the content thereof is preferably 0.001 to 30 mass %, more preferably 0.001 to 10 mass %, of the solid content, from the viewpoint of appropriately improving the fluidity of the composition for forming a resist underlayer film.

[0082] The adhesion promoter is added mainly to improve the adhesion between the substrate or resist and the composition for forming a resist underlayer film, particularly to prevent the resist from peeling off during development. Examples of the adhesion promoter 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; Examples of suitable silanes include silanes such as methyltrichlorosilane, 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; ureas such as 1,1-dimethylurea and 1,3-dimethylurea; and thiourea compounds.

[0083] When the composition for forming a resist underlayer film contains a rheology adjuster, the content thereof is preferably 0.01 to 5 mass % of the solid content, more preferably 0.1 to 2 mass %, from the viewpoint of further improving the adhesion between the semiconductor substrate or resist and the underlayer film.

[0084] Hereinafter, a resist underlayer film produced using the composition for forming a resist underlayer film according to the present invention, a method for forming a resist pattern, and a method for producing a semiconductor device will be described.

[0085] The underlayer film according to the present invention can be produced by applying the above-mentioned composition for forming a resist underlayer film onto a semiconductor substrate and baking it.

[0086] Examples of semiconductor substrates include silicon wafers, germanium wafers, and wafers of compound semiconductors such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0087] Alternatively, a semiconductor substrate having an inorganic film formed on its surface may be used. Examples of the inorganic film include polysilicon film, silicon oxide film, silicon nitride film, BPSG (Boro-Phospho Silicate Glass) film, titanium nitride film, titanium nitride oxide film, tungsten film, gallium nitride film, and gallium arsenide film. The inorganic film can be formed on the semiconductor substrate by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin coating (spin-on-glass: SOG).

[0088] The resist underlayer film-forming composition of the present invention is applied onto such a semiconductor substrate by an appropriate application method such as a spinner or coater. The composition is then baked using a heating means such as a hot plate to form a resist underlayer film. Baking conditions are appropriately selected from a baking temperature of 100 to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 120 to 350°C and the baking time is 0.5 to 30 minutes, and more preferably, the baking temperature is 150 to 300°C and the baking time is 0.8 to 10 minutes. By setting the baking temperature at or above the lower limit of the above range, the polymer can be sufficiently crosslinked. On the other hand, by setting the baking temperature at or below the upper limit of the above range, the resist underlayer film can be formed into a good thin film without being decomposed by heat.

[0089] The resist underlayer film has a thickness of, for example, 0.001 μm (1 nm) to 10 μm, preferably 0.002 μm (2 nm) to 1 μm, and more preferably 0.005 μm (5 nm) to 0.5 μm (500 nm).

[0090] Next, a photoresist layer is formed on the resist underlayer film by applying a photoresist composition solution onto the underlayer film and baking it using a known method.

[0091] The photoresist is not particularly limited as long as it is sensitive to the light used for exposure. Both negative and positive photoresists can be used. Specific examples include a positive photoresist composed of a novolak resin and a 1,2-naphthoquinone diazide sulfonic acid ester; a chemically amplified photoresist composed of a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate and a photoacid generator; a chemically amplified photoresist composed of 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 a chemically amplified photoresist composed of a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate, 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. As the photoresist, commercially available products can be used, such as V146G (trade name) manufactured by JSR Corporation, APEX-E (trade name) manufactured by Shipley Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and AR2772 and SEPR430 (trade names) manufactured by Shin-Etsu Chemical Co., Ltd. Further examples include fluorine-containing polymer photoresists such as those described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0092] Next, exposure is carried out through a predetermined mask. For the exposure, for example, i-line, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet), or EB (electron beam) can be used.

[0093] Next, development is carried out with a developer, whereby, for example, when a positive photoresist is used, the photoresist in the exposed portion is removed, and a photoresist pattern is formed.

[0094] The developer used may be an alkaline developer, such as an aqueous solution of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; or cyclic amines such as pyrrole and piperidine. Furthermore, the aqueous solution of the alkalis may be used by adding an appropriate amount of alcohols such as isopropyl alcohol or a nonionic surfactant. Among these, quaternary ammonium salts are preferred, with tetramethylammonium hydroxide and choline being more preferred. Furthermore, surfactants and the like may be added to these developers. Development conditions are appropriately selected from a development temperature of 5 to 50°C and a development time of 10 to 300 seconds.

[0095] Next, the resist underlayer film is dry-etched using the formed resist pattern as a mask, to expose the surface of the inorganic film if the inorganic film is formed on the surface of the semiconductor substrate used, or to expose the surface of the semiconductor substrate if the inorganic film is not formed on the surface of the semiconductor substrate used. [Example]

[0096] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0097] [Measurement of weight-average molecular weight Mw and polydispersity Mw / Mn] The Mw and Mw / Mn of the crude polymer and the purified polymer were calculated based on the calibration curve from each peak of the chromatogram obtained by measurement by gel permeation chromatography (GPC). The measurement conditions were as follows: <Measurement conditions> Device: HLC-8320GPC (model number) (manufactured by Tosoh Corporation) GPC columns: GF-710HQ, GF-510HQ, GF-310HQ (Showa Denko K.K.) Column temperature: 40℃ Solvent: 0.12% by mass lithium bromide monohydrate-dimethylformamide Flow rate: 1.0mL / min Injection volume: 10μL Measurement time: 60 minutes Standard sample: Polystyrene (Showa Denko K.K.) Detector: RI

[0098] [1] Polymer manufacturing [Example 1-1] <1st process> Under a nitrogen atmosphere, a 200 mL reaction flask was charged with 15.0 g (0.082 mol) of barbital (Yatsushiro Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd.) as component (b), 0.93 g (0.00408 mol) of benzyl triethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), and 155.89 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. Next, this solution was heated to reflux at 130 °C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 10,300 and the Mw / Mn was 5.8.

[0099] [ka]

[0100] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 8.1 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 15,600 and an Mw / Mn of 1.9.

[0101] [Example 1-2] <1st process> Under a nitrogen atmosphere, a 200 mL reaction flask was charged with 15.0 g (0.082 mol) of barbital (Yatsushiro Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd.) as component (b), 0.93 g (0.00408 mol) of benzyl triethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), and 155.89 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. Next, this solution was heated to reflux at 70 °C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 12,800 and the Mw / Mn was 5.9.

[0102] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 8.5 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 27,000 and an Mw / Mn of 2.1.

[0103] [Examples 1-3] <1st process> Under a nitrogen atmosphere, a 200 mL reaction flask was charged with 18.1 g (0.098 mol) of barbital (Yatsushiro Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd.) as component (b), 0.93 g (0.00408 mol) of benzyl triethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), and 167.92 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. Next, this solution was heated to reflux at 130 °C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 4,700 and the Mw / Mn was 3.8.

[0104] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 7.9 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 7,600 and an Mw / Mn of 1.5.

[0105] [Examples 1-4] <1st process> Under a nitrogen atmosphere, a 200 mL reaction flask was charged with 18.1 g (0.098 mol) of barbital (Yatsushiro Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd.) as component (b), 0.93 g (0.00408 mol) of benzyl triethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), and 62.97 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 40% by mass. Next, this solution was heated to reflux at 130 °C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 6,400 and the Mw / Mn was 3.6.

[0106] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 16.9 g of the target purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 10,300 and an Mw / Mn of 1.8.

[0107] [Examples 1-5] <1st process> Under a nitrogen atmosphere, a 300 mL reaction flask was charged with 14.9 g (0.071 mol) of 3,3'-dithiodipropionic acid (manufactured by Sakai Chemical Industry Co., Ltd., trade name: DTDPA), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemical Industry Co., Ltd., product name MA-DGIC), 1.318 g (0.0071 mol) of ethyl triphenylphosphonium bromide (manufactured by Hokko Chemical Industry Co., Ltd.), and 122.57 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. The solution was then heated to reflux at 105 ° C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 6,700 and the Mw / Mn was 5.4.

[0108] [ka]

[0109] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of cyclopentyl methyl ether (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 5.1 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 10,000 and an Mw / Mn of 3.8.

[0110] [Examples 1-6] <1st process> Under a nitrogen atmosphere, a 200 mL reaction flask was charged with 22.48 g (0.107 mol) of 3,3'-dithiodipropionic acid (manufactured by Sakai Chemical Industry Co., Ltd., trade name: DTDPA) as component (a), 25.15 g (0.105 mol) of 1,3'-diglycidylhydantoin (manufactured by Tokyo Chemical Industry Co., Ltd.) as component (b), 2.44 g (0.0107 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 200.25 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. Next, this solution was heated to reflux at 105 °C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the weight average molecular weight Mw of the obtained crude polymer was 4,100, and the polydispersity Mw / Mn was 4.1.

[0111] [ka]

[0112] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of cyclopentyl methyl ether (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of cyclopentyl methyl ether (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 5.1 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 5,700 and an Mw / Mn of 3.9.

[0113] [Examples 1-7] <1st process> Under a nitrogen atmosphere, a 300 mL reaction flask was charged with 16.5 g (0.071 mol) of phenobarbital (Yatsushiro Pharmaceutical Co., Ltd.), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd., product name MA-DGIC), 1.977 g (0.0053 mol) of tetrabutylphosphonium bromide (Hokuko Chemical Industry Co., Ltd.), and 153.87 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. This solution was then heated to reflux at 105 ° C and reacted for 24 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 33,400 and the Mw / Mn was 16.3.

[0114] [ka]

[0115] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of isopropyl alcohol (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 6.2 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 46,200 and an Mw / Mn of 10.5.

[0116] [Examples 1-8] <1st process> Under a nitrogen atmosphere, a 300 mL reaction flask was charged with 8.24 g (0.071 mol) of fumaric acid (Tokyo Chemical Industry Co., Ltd.), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (Shikoku Chemical Industry Co., Ltd., product name MA-DGIC), 1.617 g (0.0071 mol) of benzyl triethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), and 122.57 g of propylene glycol monomethyl ether to prepare a raw material solution with a solids concentration of 20% by mass. Next, this solution was heated to reflux at 120 ° C and reacted for 8 hours to obtain a crude polymer solution. To the obtained crude polymer solution, a cation exchange resin (product name: Dowex (registered trademark) 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite (registered trademark) 15JWET, Organo Corporation) were added in amounts equal to the solid content of the raw material solution, and ion exchange treatment was carried out at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction. The resulting solution was then subjected to GPC measurement and the second step. As a result of GPC measurement, the Mw of the obtained crude polymer was 4,600 and the Mw / Mn was 3.1.

[0117] [ka]

[0118] <Second process> 50 g of the crude polymer solution obtained in the first step was added to 500 g of cyclopentyl methyl ether (10 times the mass of the reaction solution) adjusted to 25°C over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was again dissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g of cyclopentyl methyl ether (10 times the mass of the reaction solution) over 30 minutes to cause reprecipitation, and the mixture was stirred for another 30 minutes. The resulting precipitate was suction filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The mixture was dried at 60°C using a vacuum dryer to obtain 4.9 g of the desired purified polymer. As a result of GPC measurement, the purified polymer obtained had an Mw of 5,100 and an Mw / Mn of 2.9.

[0119] <Reduction rate of low molecular weight components> In Examples 1-1 to 1-8, the effect of carrying out the second step was investigated by comparing the contents of low-molecular-weight components with Mw of 1,000 or less contained in the crude polymer and the purified polymer. The content of low molecular weight components and the rate of decrease thereof were calculated by the following procedure. (1) Content of low molecular weight components In a GPC graph with the horizontal axis representing elution time and the vertical axis representing detection intensity, the region below Mw 1,000 in standard polystyrene (PS) equivalent was integrated, and the resulting value was divided by the integral value of the entire region to calculate the value. (2) Reduction rate of low molecular weight components The content of low molecular weight components obtained in (1) above was calculated using the following formula. [1 - (content of low molecular weight components in purified polymer ÷ content of low molecular weight components in crude polymer)] x 100 (mass%) The results are shown in Table 1.

[0120] [Table 1]

[0121] [2] Preparation of composition for forming resist underlayer film <Example 2-1> To 0.97 g of the purified polymer obtained in Example 1-1, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0122] <Example 2-2> To 0.97 g of the purified polymer obtained in Example 1-1, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0123] <Example 2-3> To 0.97 g of the purified polymer obtained in Example 1-2, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. Thereafter, the solution was filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0124] <Example 2-4> To 0.97 g of the purified polymer obtained in Example 1-2, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0125] <Example 2-5> To 0.97 g of the purified polymer obtained in Example 1-3, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0126] <Example 2-6> To 0.97 g of the purified polymer obtained in Example 1-3, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0127] <Example 2-7> To 0.97 g of the purified polymer obtained in Example 1-4, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0128] <Example 2-8> To 0.97 g of the purified polymer obtained in Example 1-4, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0129] <Example 2-9> To 0.97 g of the purified polymer obtained in Example 1-5, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. Thereafter, the solution was filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0130] <Example 2-10> To 0.97 g of the purified polymer obtained in Example 1-5, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0131] <Example 2-11> To 0.97 g of the purified polymer obtained in Example 1-6, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. Thereafter, the solution was filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0132] <Example 2-12> To 0.97 g of the purified polymer obtained in Example 1-6, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0133] <Example 2-13> To 0.97 g of the purified polymer obtained in Example 1-7, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. Thereafter, the solution was filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0134] <Example 2-14> To 0.97 g of the purified polymer obtained in Example 1-7, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0135] <Example 2-15> To 0.97 g of the purified polymer obtained in Example 1-8, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0136] <Example 2-16> To 0.97 g of the purified polymer obtained in Example 1-8, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0137] <Comparative Example 1-1> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-1, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0138] <Comparative Example 1-2> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-1, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0139] <Comparative Example 1-3> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-2, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0140] <Comparative Example 1-4> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-2, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0141] <Comparative Example 1-5> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-3, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0142] <Comparative Example 1-6> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-3, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0143] <Comparative Example 1-7> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-4, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0144] <Comparative Example 1-8> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-4, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0145] <Comparative Example 1-9> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-5, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0146] <Comparative Example 1-10> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-5, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0147] <Comparative Example 1-11> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-6, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0148] <Comparative Example 1-12> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-6, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0149] <Comparative Example 1-13> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-7, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0150] <Comparative Example 1-14> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-7, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0151] <Comparative Example 1-15> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-8, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0152] <Comparative Example 1-16> To 4.86 g of the crude polymer solution obtained in the first step of Example 1-8, 0.24 g of tetramethoxymethyl glycoluril (Nihon Cytec Industries Co., Ltd., trade name: POWDERLINK [registered trademark] 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industry Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to form a solution. The solution was then filtered using a polyethylene microfilter with a pore size of 0.01 μm to prepare a composition for forming a resist underlayer film.

[0153] The polymers and acid catalysts used in Examples 2-1 to 2-16 and Comparative Examples 1-1 to 1-16 are listed in Tables 2 and 3 below. The abbreviations in Table 1 are as follows: PSA: p-phenolsulfonic acid 5-SSA: 5-sulfosalicylic acid

[0154] [Table 2]

[0155] [Table 3]

[0156] <Measurement of the amount of sublimation> The resist underlayer film-forming compositions prepared in Examples 2-1 to 2-16 and Comparative Examples 1-1 to 1-16 were applied to a 4-inch diameter silicon wafer substrate using a spin coater at 1,500 rpm for 60 seconds. The wafer coated with the resist underlayer film-forming composition was placed in a sublimation mass measurement device (see International Publication No. 2007 / 111147) with an integrated hot plate and baked for 120 seconds, and the sublimation material was collected in a QCM (Quartz Crystal Microbalance) sensor, i.e., a quartz crystal oscillator with electrodes. The QCM sensor can measure minute changes in mass by utilizing the property that when sublimation material adheres to the surface (electrode) of the quartz crystal oscillator, the frequency of the quartz crystal oscillator changes (decreases) depending on the mass of the material.

[0157] The detailed measurement procedure is as follows: The hot plate of the sublimation amount measurement device was heated to 205°C, and the pump flow rate was set to 1 m 3 The speed was set to / s, and the device was left to stabilize for the first 60 seconds. Immediately after that, the wafer coated with the resist underlayer film was quickly placed on the hot plate through the slide opening, and sublimated material was collected from the 60-second point to the 120-second point (60 seconds). The initial thickness of the resist underlayer film formed on the wafer was 35 nm.

[0158] The flow attachment (detection part) connecting the QCM sensor and collection funnel of the sublimation mass measurement device was used without a nozzle. Therefore, the airflow flows unrestricted from the flow path (diameter: 32 mm) of the chamber unit, which is 30 mm away from the sensor (quartz crystal oscillator). The QCM sensor used electrodes made of a material (AlSi) primarily composed of silicon and aluminum, with a quartz crystal oscillator diameter (sensor diameter) of 14 mm, an electrode diameter on the quartz crystal oscillator surface of 5 mm, and a resonant frequency of 9 MHz.

[0159] The frequency change obtained was converted into grams from the characteristic value of the quartz crystal oscillator used in the measurement, and the amount of sublimation material per wafer coated with the resist underlayer film was determined. The results are shown in Table 4. In Table 4, X represents a film formed from a composition containing the crude polymer synthesized in the first step, and Y represents a film formed from a composition containing the purified polymer purified in the second step. Table 4 also shows the effect on the sublimate of the presence or absence of a purification step by reprecipitation.

[0160] [Table 4]

[0161] From the above, it was confirmed that, according to the production method of the present invention, the content of low molecular weight components contained in the synthesized polymer can be significantly reduced by carrying out a purification step by reprecipitation (see Table 4). Furthermore, the resist underlayer films obtained from the resist underlayer film-forming compositions containing the purified polymer (Examples 2-1 to 2-16) showed less generation of sublimates than the resist underlayer films obtained from the resist underlayer film-forming compositions containing the crude polymer (Comparative Examples 1-1 to 1-16).

Claims

1. a first step of reacting a monomer represented by the following formula (a) with a monomer represented by the following formula (b) in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt to synthesize a crude polymer having a repeating unit represented by the following formula (1), and then adding a cation exchange resin and an anion exchange resin to the obtained crude polymer solution to perform an ion exchange treatment; a second step of mixing the solution containing the crude polymer obtained in the first step with a poor solvent to precipitate a purified polymer having a repeating unit represented by formula (1), and filtering the precipitate. 【Chemistry 2】 In formula (1) and formula (a), A's each independently represent a hydrogen atom, a methyl group, or an ethyl group; in formula (1), formula (a), and formula (b), Q 1 and Q 2 is expressed by equation (2) or equation (3): 【Chemistry 2】 [In the formula, Q 3 represents an alkylene group having 1 to 10 carbon atoms, which may contain a sulfide bond or a disulfide bond, an alkenylene group having 2 to 10 carbon atoms, a phenylene group, a naphthylene group, or an anthrylene group, and the phenylene group, naphthylene group, and anthrylene group may each independently be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; each B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms; each n independently represents 0 or 1; each m independently represents 0 or 1; and X represents a group represented by formula (4), formula (5), or formula (6): 【Transformation 3】 (In the formula, R 1 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the alkyl and alkenyl groups may be substituted with a halogen atom, a hydroxy group, or a cyano group; the benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxy group; the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; 1 may be bonded to each other to form a ring having 3 to 6 carbon atoms; R 2 represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms.) where Q 1 and Q 2 At least one of the groups contains a structure represented by formula (3).

2. 2. The method for producing a polymer according to claim 1, wherein the organic solvent used in the first step is one or more selected from the group consisting of benzene, toluene, xylene, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, and N-methylpyrrolidone.

3. 3. The method for producing a polymer according to claim 2, wherein the organic solvent is propylene glycol monomethyl ether.

4. The method for producing a polymer according to any one of claims 1 to 3, wherein the poor solvent used in the second step is one or more solvents selected from the group consisting of diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropyl alcohol.

5. 5. The method for producing a polymer according to claim 4, wherein the poor solvent is isopropyl alcohol.

6. The method for producing a polymer according to any one of claims 1 to 5, wherein low-molecular-weight components having a weight-average molecular weight of 1,000 or less are removed from the crude polymer in the second step.

7. 7. The method for producing a polymer according to claim 1, wherein 30% by mass or more of the low molecular weight components contained in the crude polymer are removed by the second step.

8. A method for producing a composition for forming a resist underlayer film, comprising mixing the polymer obtained by the method according to any one of claims 1 to 7 with an organic solvent.

9. A first step of reacting a monomer represented by the following formula (a) and a monomer represented by the following formula (b) in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt to synthesize a crude polymer having a repeating unit represented by the following formula (1), and adding a cation exchange resin and an anion exchange resin to the obtained crude polymer solution to perform an ion exchange treatment; a second step of mixing the solution containing the crude polymer obtained in the first step with a poor solvent to precipitate a purified polymer having a repeating unit represented by formula (1), and filtering the precipitate; applying the composition containing the purified polymer obtained in the second step onto a substrate and baking the composition to form a thin film; A method for suppressing the production of sublimates during thin film formation, comprising removing 54.6 mass % or more of low-molecular-weight components having a weight-average molecular weight of 1,000 or less from the crude polymer by the second step. 【Chemistry 4】 In formula (1) and formula (a), A's each independently represent a hydrogen atom, a methyl group, or an ethyl group; in formula (1), formula (a), and formula (b), Q 1 and Q 2 each independently represent a group represented by formula (2) or formula (3): 【Transformation 5】 [wherein Q 3 represents an alkylene group having 1 to 10 carbon atoms which may contain a sulfide bond or a disulfide bond, an alkenylene group having 2 to 10 carbon atoms, a phenylene group, a naphthylene group, or an anthrylene group, and the phenylene group, naphthylene group, and anthrylene group may each independently be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a phenyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; each B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms; each n independently represents 0 or 1; each m independently represents 0 or 1; and X represents a group represented by formula (4), formula (5), or formula (6): 【Transformation 6】 (In the formula, R 1 s each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the alkyl group and alkenyl group may be substituted with a halogen atom, a hydroxy group, or a cyano group. The benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxy group. The phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms. Two R 1 s may be bonded to each other to form a ring having 3 to 6 carbon atoms; R 2 represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms.) Here, at least one of Q 1 and Q 2 contains a structure represented by formula (3).

10. A first step of synthesizing a crude polymer having a repeating unit represented by the following formula (1-1) or (1-3) by reacting any one of the monomers represented by the following formula (a) with a monomer represented by the following formula (b) in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt, and then adding a cation exchange resin and an anion exchange resin to the obtained crude polymer solution to perform an ion exchange treatment; a second step of mixing the solution containing the crude polymer obtained in the first step with a poor solvent, followed by stirring for 10 minutes or more to precipitate a purified polymer having a repeating unit represented by formula (1-1) or (1-3), and filtering the precipitate; applying the composition containing the purified polymer obtained in the second step onto a substrate and baking the composition to form a thin film; 10. The method for suppressing the generation of sublimates during thin film formation according to claim 9, further comprising removing 54.6 mass% or more of low-molecular-weight components having a weight-average molecular weight of 1,000 or less from the crude polymer by the second step. 【Transformation 7】 【Transformation 8】

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