Composition for forming a resist underlayer film

Abstract

Provided is a composition which is for forming a resist underlayer film and with which the amount of a sublimate derived from a low-molecular-weight component such as an oligomer can be reduced, the composition comprising, for example, an organic solvent and a polymer having a repeating unit represented by formula (1-1), wherein the content of a low-molecular-weight component having a weight average molecular weight of 1,000 or less is 10 mass% or less in the polymer.

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a resist underlayer film, and more specifically, to a composition for forming a resist underlayer film containing a condensation polymer obtained by reacting monomers containing a pyrimidinetrione structure or a triazinetrione structure. [Background technology]

[0002] Conventionally, a method of producing the above-mentioned condensation polymer by reacting monoallyl diglycidyl isocyanuric acid with 5,5-diethylbarbituric acid is known. For example, in Synthesis Example 1 of Patent Documents 1 and 2, it is described that each of the above compounds and benzyltriethylammonium chloride were dissolved in propylene glycol monomethyl ether, and then reacted at 130°C for 24 hours to obtain a solution containing a polymer with a weight-average molecular weight of 6,800.

[0003] Patent Documents 1 and 2 further describe the preparation of an anti-reflective film-forming composition or a resist underlayer-forming composition for EUV lithography using a solution containing the obtained polymer.

[0004] Polymers obtained through chemical synthesis are typically aggregates of molecules with different molecular weights (degrees of polymerization). 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 higher the content of low-molecular-weight components in a polymer, the lower the average molecular weight of the polymer and the greater its polydispersity (Mw / Mn).

[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. As a result, when an anti-reflective film-forming composition or an EUV lithography resist underlayer-forming composition prepared using these polymers is applied to a substrate and baked to form a film, a large amount of sublimation material derived from these low molecular weight components is generated. This sublimation material contaminates the inside of the bake apparatus, specifically the top plate directly above the heating plate on which the substrate is placed, and the inside of the exhaust duct. Since the inside of the bake apparatus must be cleaned each time it becomes contaminated with sublimation material, there is a strong demand to reduce the amount of sublimation material generated from the viewpoint of improving productivity. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2005 / 098542 [Patent Document 2] International Publication No. 2013 / 018802 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention has been made in view of the above circumstances, and aims to provide a resist underlayer film formation composition that can reduce the amount of sublimation generated from low molecular weight components such as oligomers. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of the present invention have found that by reducing the content of low molecular weight components with a weight-average molecular weight of 1,000 or less in the polymer included in the resist underlayer film forming composition to 10% by mass or less, the amount of sublimation generated during the formation of the resist underlayer film can be reduced, and thus the present invention has been completed.

[0009] That is, the present invention provides a composition for forming a resist underlayer film as follows. 1. A composition for forming a resist underlayer film, comprising a polymer having a repeating unit represented by the following formula (1) and an organic solvent, wherein the content of low molecular weight components having a weight average molecular weight of 1,000 or less in the polymer is 10% by mass or less. [Chemical formula] {In formula (1), A independently represents a hydrogen atom, a methyl group or an ethyl group, and Q 1 and Q 2 are formula (2) or formula (3): [Chemical formula] [In the formula, Q 3 represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a phenylene group, a naphthylene group or an anthrylene group which may contain a sulfide bond or a disulfide bond. The phenylene group, naphthylene group and anthrylene group may be independently 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; B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms; n independently represents 0 or 1; m independently represents 0 or 1; X is formula (4) or formula (5): [Chemical formula] (In the formula, R 1Each 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. The above alkyl group and alkenyl group may be substituted with a halogen atom, a hydroxy group or a cyano group. The above benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxy group. The above 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 Rs 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. The above 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.)] represents. However, at least one of Q 1 and Q 2 shall contain a structure represented by formula (3).} 2. Further, the resist underlayer film-forming composition according to claim 1, which contains a crosslinking agent. 3. Further, the resist underlayer film-forming composition according to claim 1 or 2, which contains an acid catalyst. 4. A resist underlayer film obtained from the resist underlayer film-forming composition according to any one of claims 1 to 3. 5. A polymer having a repeating unit represented by the following formula (1), wherein the content of a low molecular weight component having a weight average molecular weight of 1,000 or less in the polymer is 10% by mass or less.

Chemical formula

Chemical formula

[0010] According to the resist underlayer film formation composition of the present invention, the generation of sublimation products during the formation of the resist underlayer film is suppressed, thereby reducing the frequency of cleaning the equipment and contributing to improved productivity of resist underlayer film formation. [Modes for carrying out the invention]

[0011] The resist underlayer film forming composition according to the present invention comprises a polymer having repeating units represented by the following formula (1) and an organic solvent, characterized in that the content of low molecular weight components with a weight-average molecular weight (hereinafter referred to as Mw) of 1,000 or less in the polymer is 10% by mass or less. In this invention, low molecular weight components mean polymers having repeating units represented by formula (1), such as oligomers, whose Mw does not exceed 1,000, and do not include unreacted monomer components or other components such as catalysts used in the polymerization reaction. Furthermore, in this invention, Mw is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0012] [ka]

[0013] In the formula, A independently represents a hydrogen atom, a methyl group, or an ethyl group, and Q 1 and Q 2 This represents equation (2) or equation (3).

[0014] [ka]

[0015] In the formula, Q 3This represents a C1-C10 alkylene group, a C2-C10 alkenylene group, a phenylene group, a naphthylene group, or anthrylene group, which may contain a sulfide bond or a disulfide bond. The phenylene group, naphthylene group, and anthrylene group may be independently substituted with a group selected from the group consisting of a C1-C6 alkyl group, a phenyl group, a halogen atom, a C1-C6 alkoxy group, a nitro group, a cyano group, a hydroxyl group, and a C1-C6 alkylthio group. B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms. n is either 0 or 1, independently of each other. m is either 0 or 1, independently of each other. X is a base represented by equation (4) or equation (5).

[0016] [ka]

[0017] In the formula, R 1 Each independently represents a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C3-C6 alkenyl group, a benzyl group, or a phenyl group. The alkyl and alkenyl groups may be substituted with halogen atoms, hydroxyl groups, or cyano groups. The benzyl group may have a hydrogen atom on the aromatic ring substituted with a hydroxyl group. The phenyl group may be substituted with a group selected from the group consisting of a C1-C6 alkyl group, a halogen atom, a C1-C6 alkoxy group, a nitro group, a cyano group, a hydroxyl group, and a C1-C6 alkylthio group, and two R 1 These atoms may be bonded to each other to form a ring with 3 to 6 carbon atoms.

[0018] R 2This represents a halogen atom, a C1-C6 alkyl group, a C3-C6 alkenyl group, a benzyl group, or a phenyl group. The phenyl group may be substituted with a group selected from the group consisting of a C1-C6 alkyl group, a halogen atom, a C1-C6 alkoxy group, a nitro group, a cyano group, a hydroxyl group, and a C1-C6 alkylthio group.

[0019] However, Q 1 and Q 2 At least one of them shall include the structure represented by formula (3).

[0020] Alkylene groups having 1 to 10 carbon atoms can be linear, branched, or cyclic, and examples include methylene, ethylene, propylene, pentamethylene, cyclohexylene, 2-methylpropylene, and 1-methylethylidene. Furthermore, alkylene groups having 1 to 10 carbon atoms that contain sulfide or disulfide bonds can be those represented by the following formulas.

[0021] [ka] (In the formula, * represents a bond.)

[0022] The alkenylene group having 2 to 10 carbon atoms can be linear, branched, or cyclic. Examples include etenylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octenylene, and nonerine groups.

[0023] The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic. Examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, neopentyl, n-hexyl, cyclopentyl, and cyclohexyl groups.

[0024] The alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and examples include methoxy, ethoxy, i-propoxy, n-pentyloxy, n-hexyloxy, and cyclohexyloxy groups.

[0025] The alkylthio group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and examples include methylthio, ethylthio, i-propylthio, n-pentylthio, and cyclohexylthio groups.

[0026] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0027] Two R's 1 Examples of rings with 3 to 6 carbon atoms formed by the bonding of these atoms include cyclobutane rings, cyclopentane rings, and cyclohexane rings.

[0028] In this invention, Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0029] Examples of repeating units represented by equation (1) include those shown in equations (1-1) to (1-4) below, but are not limited to these.

[0030] [ka]

[0031] The content of low molecular weight components with Mw of 1,000 or less in the above polymer is 10% by mass or less, but from the viewpoint of further reducing the amount of sublimation produced, it is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0032] The Mw of the above polymer is preferably 1,000 to 200,000, more preferably 2,000 to 100,000, even more preferably 3,000 to 50,000, still more preferably 4,000 to 30,000, and most preferably 5,000 to 20,000, and the polydispersity Mw / Mn of the polymer is preferably 10.5 or less, more preferably 2.1 or less (Mn represents the number-average molecular weight measured under the same conditions as Mw; the same applies hereinafter).

[0033] The polymer with reduced low molecular weight component content, as described above, can be synthesized by a method comprising the following first and second steps. In the following description, "crude polymer" refers to the polymer synthesized in the first step, and "purified polymer" refers to the polymer obtained from the solution containing the crude polymer via the second step.

[0034] <1st process> The first step is to react a monomer represented by the following formula (a) (hereinafter sometimes abbreviated as component (a)) and 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 repeating units represented by the following formula (1).

[0035] [ka]

[0036] In the formula, A, Q 1 and Q 2 The same applies as above.

[0037] (a) Specific examples of components include the following: Q 1 However, examples of compounds that are the group represented by formula (2) include diglycidyl ester compounds and diglycidyl ether compounds.

[0038] Examples of diglycidyl ester compounds include diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl phthalate, 2,5-dimethylterephthalate, 2,5-diethylterephthalate, 2,3,5,6-tetrachloroterephthalate, 2,3,5,6-tetrabromoterephthalate, 2-nitroterephthalate, and 2,3,5,6-tetrabromoterephthalate. Diglycidyl oroterephthalate, 2,5-dihydroxyterephthalate, 2,6-dimethylterephthalate, 2,5-dichloroterephthalate, 2,3-dichloroisophthalate, 3-nitroisophthalate, 2-bromoisophthalate, 2-hydroxyisophthalate, 3-hydroxyisophthalate, 2-methoxy Diglycidyl isophthalate, diglycidyl 5-phenylisophthalate, diglycidyl 3-nitrophthalate, diglycidyl 3,4,5,6-tetrachlorophthalate, diglycidyl 4,5-dichlorophthalate, diglycidyl 4-hydroxyphthalate, diglycidyl 4-nitrophthalate, diglycidyl 4-methylphthalate, diglycidyl 3,4,5,6-tetrafluorophthalate, 2,6-naphthalenedicarbon Examples include diglycidyl acids, 1,2-naphthalenedicarboxylic acid diglycidyl esters, 1,4-naphthalenedicarboxylic acid diglycidyl esters, 1,8-naphthalenedicarboxylic acid diglycidyl esters, anthracene-9,10-dicarboxylic acid diglycidyl esters, 1,2-cyclohexanedicarboxylic acid diglycidyl esters, dithiodiglycolate diglycidyl esters, 2,2'-thiodiglycolate diglycidyl esters, and diglyclycolate diglycidyl esters.

[0039] 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.

[0040] Q 1 However, examples of compounds that are the group represented by formula (3) include diglycidyl barbiturate compounds and diglycidyl isocyanurate compounds.

[0041] Examples of diglycidyl barbiturate compounds include 1,3-diglycidyl-5,5-diethylbarbiturate, 1,3-diglycidyl-5-phenyl-5-ethylbarbiturate, 1,3-diglycidyl-5-ethyl-5-isoamylbarbiturate, 1,3-diglycidyl-5-allyl-5-isobutylbarbiturate, 1,3-diglycidyl-5-allyl-5-isopropylbarbiturate, 1,3-diglycidyl-5-β-bromoallyl-5-sec-butylbarbiturate, and 1,3-di Examples include glycidyl-5-ethyl-5-(1-methyl-1-butenyl)barbituric acid, 1,3-diglycidyl-5-isopropyl-5-β-bromoarylbarbituric acid, 1,3-diglycidyl-5-(1-cyclohexyl)-5-ethylmalonylurea, 1,3-diglycidyl-5-ethyl-5-(1-methylbutyl)malonylurea, 1,3-diglycidyl-5,5-diallylmalonylurea diglycidyl, and 1,3-diglycidyl-5-ethyl-5-n-butylbarbituric acid.

[0042] 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.

[0043] (b) Specific examples of components include the following: Q 2 However, examples of compounds that are the group represented by formula (2) include dicarboxylic acid compounds.

[0044] 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-dichloro Examples 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, and itaconic acid, as well as 3,3'-(5-methyl-1-2,4,6-trioxo-1,3,5-triazine-1,3-diyldipropionic acid and 3,3'-dithiodipropionic acid.

[0045] Q 2 However, examples of compounds that are the group represented by formula (3) include barbiturate compounds and isocyanurate compounds.

[0046] Examples of barbiturate 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-isobutyl Examples include barbituric acid, 5-allyl-5-isopropylbarbituric acid, 5-β-bromoaryl-5-sec-butylbarbituric acid, 5-ethyl-5-(1-methyl-1-butenyl)barbituric acid, 5-isopropyl-5-β-bromoarylbarbituric 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-n-butylbarbituric acid.

[0047] Examples of isocyanuric acid compounds 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.

[0048] The components (a) and (b) exemplified above can usually be combined by selecting one compound from each, but are not limited to this, and multiple compounds may be selected and used for either or both of components (a) and (b). However, at least one of components (a) and (b) must contain a compound having a skeleton selected from barbituric acid and isocyanuric acid.

[0049] Examples of components (a) that can be suitably used in the present invention include, but are not limited to, the following compounds.

[0050] [ka]

[0051] Furthermore, the following compounds are examples of components (b) that can be suitably used in the present invention, but are not limited to these.

[0052] [ka]

[0053] The mixing ratio (molar ratio) of component (a) and component (b) is not particularly limited, but from the viewpoint of suppressing the residue of unreacted component (a) having epoxy groups, it is preferable to have equimolar amounts of component (a) and component (b), or to have an excess of component (b) relative to component (a), with (a):(b) = 1:1.21 to 1:1 being more preferable. By keeping the above mixing ratio below the upper limit, it becomes easier to obtain a polymer having the desired Mw.

[0054] Examples of quaternary phosphonium salts include 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. In the present invention, ethyltriphenylphosphonium bromide and tetrabutylphosphonium bromide can be suitably used.

[0055] 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, and methyltrioctylammonium chloride. In the present invention, benzyltriethylammonium chloride can be preferably used.

[0056] The amounts of the above-mentioned quaternary phosphonium salt and quaternary ammonium salt are not particularly limited as long as they are sufficient to allow the reaction to proceed, but are preferably 0.1 to 10.0%, more preferably 1.0 to 5.0%, relative to the number of moles of component (a).

[0057] The organic solvent used in the first step can 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 can be used individually or in combination of two or more. In this invention, propylene glycol monomethyl ether is preferred, considering the applications of the composition using the final polymer.

[0058] The amount of organic solvent used can be appropriately set according to the type and amount of each component mentioned above, and is not particularly limited. In this invention, considering the efficient progress of the reaction, the total solid content concentration of each component is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. Here, the solid content in the solid content concentration of the solution refers to the components other than the solvent that make up the solution.

[0059] The reaction temperature in the first step is usually 200°C or lower, preferably 150°C or lower, and more preferably 130°C or lower, considering the boiling point of the organic solvent used. The lower limit of the reaction temperature is not particularly limited, but considering the need to quickly complete the condensation reaction of components (a) and (b), it is preferably 50°C or higher, and more preferably 60°C or higher. Furthermore, reflux may be used during heating.

[0060] The reaction time cannot be precisely defined as it depends on the reaction temperature and the reactivity of the raw materials, but it is usually around 1 to 48 hours, and when the reaction temperature is 60 to 130°C, it is generally around 15 to 30 hours.

[0061] <Second process> The second step involves 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 and filter out the crude polymer having repeating units represented by formula (1). This second step removes the low molecular weight components contained in the crude polymer. The crude polymer solution may be the reaction solution obtained in the first step, or it may be a crude polymer isolated by drying or other appropriate means and dissolved in an appropriate solvent. In the latter case, the organic solvent used in the first step can be used as the solvent.

[0062] As the poor solvent used in the second step, a solvent that has low polymer solubility and dissolves low molecular weight components can be used. Examples include diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropyl alcohol. These can be used individually or in combination of two or more. In the present invention, isopropyl alcohol can be suitably used.

[0063] In the present invention, when mixing the crude polymer solution and the poor solvent, the mixing order is not particularly limited. The crude polymer solution may be added to the poor solvent, or the poor solvent may be added to the crude polymer solution. However, considering the removal of more low molecular weight components, the method of adding the crude polymer solution to the poor solvent is preferred.

[0064] Furthermore, when mixing the two, the mixture may be added gradually by dropwise addition or the entire amount may be added at once. However, considering the reduction of the content of low molecular weight components in the purified polymer, the method of adding it gradually by dropwise addition is preferred.

[0065] The amount of poor solvent used in the crude polymer solution is not particularly limited, as long as it is an amount that does not cause low molecular weight components to precipitate and can sufficiently precipitate the polymer. However, it is preferably 2 to 30 times the mass of the crude polymer solution, more preferably 5 to 20 times, and even more preferably 5 to 15 times the mass.

[0066] The mixing temperature can be set appropriately within the range from the melting point to the boiling point of the solvent used, and is not particularly limited, but is usually around -20 to 50°C. Considering the ease of precipitate formation and workability, 0 to 50°C is preferred, and 0 to 30°C is more preferred.

[0067] A preferred embodiment of the above mixing operation is, for example, the gradual addition of a crude polymer solution with a total solids content of 5 to 50% by mass to a poor solvent of 5 to 20 times its mass, by adding the crude polymer solution gradually over 15 minutes to 1 hour per 50 g, but is not limited thereto.

[0068] After the mixing operation is complete, stirring may be continued for a predetermined time to remove more low molecular weight components. In this case, the stirring time is preferably 10 minutes to 2 hours, more preferably 15 minutes to 1 hour.

[0069] Furthermore, in order to further reduce the polydispersity of the polymer, the precipitate filtered in the second step may be dissolved again in the organic solvent used in the first step, the resulting solution may be mixed with the poor solvent, and the resulting precipitate may be filtered off.

[0070] Through the second step described above, 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 can be removed, and a polymer (purified polymer) is finally obtained in which the low molecular weight component content is 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0071] As an organic solvent, any solvent capable of dissolving solid components can be used without particular limitations. In particular, since the resist underlayer film forming composition according to the present invention is used in a uniform solution state, it is recommended to use a solvent commonly used in lithography processes in combination, considering its coating performance.

[0072] Examples of the above organic solvents 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. Examples include 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 individually or in combination of two or more.

[0073] The solid content concentration of the resist underlayer film forming composition of the present invention is set appropriately considering the viscosity and surface tension of the composition, the thickness of the thin film to be produced, etc., but is usually about 0.1 to 20.0% by mass, preferably 0.5 to 15.0% by mass, and more preferably 1.0 to 10.0% by mass. The solid content in the solid content concentration of the composition referred to herein means components other than the solvent contained in the resist underlayer film forming composition of the present invention.

[0074] The resist underlayer film forming composition of the present invention may contain optional components such as crosslinking agents, acid catalysts (organic acids) that promote crosslinking reactions, surfactants, light absorbers, rheology modifiers, and adhesion aids, to the extent that they do not impair the effects of the present invention.

[0075] There are no particular restrictions on the crosslinking agent, but compounds having at least two crosslinking groups in the molecule can be suitably used. For example, melamine-based compounds and substituted urea-based compounds having crosslinking groups such as methylol groups and methoxymethyl groups can be used. Specifically, these are compounds such as methoxymethylated glycoluryl or methoxymethylated melamine, for example, tetramethoxymethyl glycoluryl, tetrabutoxymethyl glycoluryl, or hexamethoxymethylmelamine. Compounds such as tetramethoxymethylurea and tetrabutoxymethylurea can also be used. These crosslinking agents can undergo crosslinking reactions by self-condensation. They can also undergo crosslinking reactions with hydroxyl groups in polymers having the structure represented by formula (1). As a result of such crosslinking reactions, the underlying film formed becomes strong and has low solubility in organic solvents. These crosslinking agents may be used individually or in combination of two or more.

[0076] When the above resist underlayer film forming composition contains a crosslinking agent, the amount of the crosslinking agent varies depending on the organic solvent used, the substrate used, the required solution viscosity, the required film shape, etc. However, from the viewpoint of curability of the coating film, it is preferably 0.01 to 50% by mass of the solid content, more preferably 0.1 to 40% by mass, and even more preferably 0.5 to 30% by mass. These crosslinking agents may undergo crosslinking reactions by self-condensation, but if crosslinkable substituents are present in the polymer of the present invention, they can undergo crosslinking reactions with those crosslinkable substituents.

[0077] Examples of acid catalysts 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, p-trifluoromethylbenzenesulfonic acid-2,4-dinitrobenzyl, and phenyl-bis(trichloromethyl)-s-triadyl Examples include acid compounds that generate acid upon heat or light, such as N-hydroxysuccinimide trifluoromethanesulfonate; iodonium salt-based acid generators such as diphenyliodonium hexafluorophosphonate, diphenyliodonium trifluoromethanesulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt-based acid generators such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium trifluoromethanesulfonate. In the present invention, sulfonic acid compounds and carboxylic acid compounds can be preferably used among these. Furthermore, these acid catalysts may be used individually or in combination of two or more.

[0078] If the above resist underlayer film forming composition contains an acid catalyst, its content is preferably 0.0001 to 20% by mass, more preferably 0.01 to 15% by mass, and even more preferably 0.1 to 10% by mass, based on the solid content, from the viewpoint of sufficiently promoting the crosslinking reaction.

[0079] Surfactants are added to further improve the coatability of 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. Vitamin fatty acid esters; nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters including polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate and polyoxyethylene sorbitan tristearate; F-Top® EF301, EF303, EF352 (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac® F171, F173, R-30, R-30N, R-40, R-40-LM (manufactured by DIC Corporation), Florard FC430, FC431 (3M Examples include fluorine-based surfactants such as Asahi Guard® AG710, Surflon® S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by AGC Inc.), and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants may be used individually or in combination of two or more.

[0080] If the above resist underlayer film forming composition contains a surfactant, its content is preferably 0.0001 to 10% by mass, and more preferably 0.01 to 5% by mass, of the solid content, from the viewpoint of improving the coatability on the semiconductor substrate.

[0081] Examples of light absorbers include commercially available light absorbers listed in "Technology and Market of Industrial Dyes" (CMC Publishing) and "Dye Handbook" (edited by the Society of Synthetic Organic Chemistry), such as CIDisperse 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; CID isperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72 and 73; CIDisperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; CIDisperse Violet 43; CIDisperse Blue 96; CIFluorescent Brightening Agents 112, 135, and 163; CISolvent Orange 2 and 45; CISolvent Red 1, 3, 8, 23, 24, 25, 27, and 49; CIPigment Green 10; CIPigment Brown 2, etc., can be suitably used.

[0082] When the above-mentioned light-absorbing agent is included, its content is usually preferably 0.1 to 10% by mass, and more preferably 0.1 to 5% by mass, relative to the solid content.

[0083] Rheology modifiers are added primarily to improve the fluidity of the resist underlayer film formation composition, and especially in the baking process, to improve the uniformity of the resist underlayer film thickness and the filling of the resist underlayer film formation composition into the holes. Examples of rheology modifiers include phthalate derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives such as dinormal butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyldecyl adipate; maleic acid derivatives such as dinormal butyl malate, diethyl malate, and dinonyl malate; oleic acid derivatives such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate; and stearic acid derivatives such as normal butyl stearate and glyceryl stearate.

[0084] If the above-mentioned resist underlayer film forming composition contains a rheology modifier, its content is preferably 0.001 to 30% by mass, and more preferably 0.001 to 10% by mass, of the solid content, from the viewpoint of moderately improving the fluidity of the resist underlayer film forming composition.

[0085] Adhesion aids are added primarily to improve the adhesion between the substrate or resist and the resist underlayer film forming composition, and especially to prevent the resist from peeling off during development. Examples of adhesion aids 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; and methyl Examples include silanes such as roltrichlorosilane, 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.

[0086] If the above-mentioned resist underlayer film forming composition contains a rheology modifier, its content is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass, of the solid content, from the viewpoint of further improving the adhesion between the semiconductor substrate or resist and the underlayer film.

[0087] The following describes a resist underlayer film, a resist pattern formation method, and a semiconductor device manufacturing method, all of which are produced using the resist underlayer film formation composition according to the present invention.

[0088] The underlayer film according to the present invention can be manufactured by applying the above-mentioned resist underlayer film forming composition onto a semiconductor substrate and firing it.

[0089] Examples of semiconductor substrates include silicon wafers, germanium wafers, and compound semiconductor wafers such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0090] Alternatively, a semiconductor substrate with an inorganic film formed on its surface may be used. Examples of the inorganic film include polysilicon films, silicon oxide films, silicon nitride films, BPSG (Boro-Phospho-Silicate Glass) films, titanium nitride films, titanium oxide nitride films, tungsten films, gallium nitride films, and gallium arsenide films. The inorganic film can be formed on the semiconductor substrate by methods such as ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, and spin coating (spin-on-glass: SOG).

[0091] The resist underlayer film forming composition of the present invention is applied to such a semiconductor substrate by an appropriate coating method such as a spinner or coater. Subsequently, the resist underlayer film is formed by firing using a heating means such as a hot plate. The firing conditions are appropriately selected from a firing temperature of 100 to 400°C and a firing time of 0.3 to 60 minutes. Preferably, the firing temperature is 120 to 350°C and the firing time is 0.5 to 30 minutes, and more preferably, the firing temperature is 150 to 300°C and the firing time is 0.8 to 10 minutes. By setting the firing temperature above the lower limit of the above range, the polymer can be sufficiently crosslinked. On the other hand, by setting the firing temperature below the upper limit of the above range, a good thin film can be formed without the resist underlayer film decomposing due to heat.

[0092] The thickness of the resist underlayer film is, 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).

[0093] Next, a photoresist layer is formed on the resist underlayer film. The photoresist layer can be formed by a well-known method, which involves coating the underlayer film with a photoresist composition solution and then firing it.

[0094] There are no particular limitations on the photoresist as long as it is sensitive to the light used for exposure. Both negative and positive photoresists can be used. Specific examples include, for instance, a positive photoresist consisting of novolac resin and 1,2-naphthoquinone diazide sulfonic acid ester; a chemically amplified photoresist consisting of a binder having a group that decomposes with acid to increase the alkali dissolution rate and a photoacid generator; a chemically amplified photoresist consisting of a low-molecular-weight compound that decomposes with acid to increase the alkali dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; and a chemically amplified photoresist consisting of a binder having a group that decomposes with acid to increase the alkali dissolution rate, a low-molecular-weight compound that decomposes with acid to increase the alkali dissolution rate of the photoresist, and a photoacid generator. Commercially available photoresists can be used, such as V146G from JSR Corporation, APEX-E from Cyprey, PAR710 from Sumitomo Chemical Co., Ltd., and AR2772 and SEPR430 from Shin-Etsu Chemical Co., Ltd. Additionally, 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), can be used.

[0095] Next, exposure is performed through a predetermined mask. For exposure, for example, i-rays, KrF excimer lasers, ArF excimer lasers, EUV (extreme ultraviolet), or EB (electron beam) can be used.

[0096] Next, development is performed using a developing solution. This removes the photoresist from the exposed areas, for example, if a positive-type photoresist is used, and forms a photoresist pattern.

[0097] As the developer, an alkaline developer is used, and aqueous solutions of the following alkalis can be used: 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; and cyclic amines such as pyrrole and piperidine. Furthermore, an appropriate amount of alcohol such as isopropyl alcohol and a nonionic surfactant can be added to the aqueous solution of the above alkalis. Among these, quaternary ammonium salts are preferred, and tetramethylammonium hydroxide and choline are more preferred. Furthermore, surfactants can also be added to these developers. As for the development conditions, a development temperature of 5 to 50°C and a development time of 10 to 300 seconds can be appropriately selected.

[0098] Next, the resist underlayer film is dry-etched using the formed resist pattern as a mask. At this time, if the inorganic film is formed on the surface of the semiconductor substrate used, the surface of the inorganic film is exposed; if the inorganic film is not formed on the surface of the semiconductor substrate used, the surface of the semiconductor substrate is exposed. [Examples]

[0099] 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.

[0100] [Measurement of weight-average molecular weight (Mw) and polydispersity (Mw / Mn)] The Mw and Mw / Mn of the crude and purified polymers were calculated based on a calibration curve from the peaks in the chromatograms obtained 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 (manufactured by Showa Denko K.K.) Column temperature: 40℃ Solvent: 0.12% by mass of lithium bromide-1-hydrate-dimethylformamide Flow rate: 1.0mL / min Injection volume: 10μL Measurement time: 60 minutes Standard sample: Polystyrene (manufactured by Showa Denko Corporation) Detector: RI

[0101] [1] Polymer production [Example 1-1] <1st process> Under a nitrogen atmosphere, 15.0 g (0.082 mol) of barbital (manufactured by Yashiro Pharmaceutical Co., Ltd.), component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemicals, Ltd.), component (b), 0.93 g (0.00408 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 155.89 g of propylene glycol monomethyl ether were charged into a 200 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. This solution was then heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 10,300 and an Mw / Mn ratio of 5.8.

[0102] [ka]

[0103] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the purified polymer had a Mw of 15,600 and an Mw / Mn ratio of 1.9.

[0104] [Examples 1-2] <1st process> Under a nitrogen atmosphere, 15.0 g (0.082 mol) of barbital (manufactured by Yashiro Pharmaceutical Co., Ltd.), component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemicals, Ltd.), component (b), 0.93 g (0.00408 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 155.89 g of propylene glycol monomethyl ether were charged into a 200 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 12,800 and an Mw / Mn ratio of 5.9.

[0105] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the purified polymer had a Mw of 27,000 and an Mw / Mn ratio of 2.1.

[0106] [Examples 1-3] <1st process> Under a nitrogen atmosphere, 18.1 g (0.098 mol) of barbital (manufactured by Yashiro Pharmaceutical Co., Ltd.), component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemicals, Ltd.), component (b), 0.93 g (0.00408 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 167.92 g of propylene glycol monomethyl ether were charged into a 200 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 4,700 and an Mw / Mn ratio of 3.8.

[0107] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the purified polymer had a Mw of 7,600 and an Mw / Mn ratio of 1.5.

[0108] [Examples 1-4] <1st process> Under a nitrogen atmosphere, 18.1 g (0.098 mol) of barbital (manufactured by Yashiro Pharmaceutical Co., Ltd.), component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemicals, Ltd.), component (b), 0.93 g (0.00408 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 62.97 g of propylene glycol monomethyl ether were charged into a 200 mL reaction flask to prepare a raw material solution with a solid content of 40% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 6,400 and an Mw / Mn ratio of 3.6.

[0109] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction 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 desired purified polymer. GPC measurements revealed that the purified polymer had a Mw of 10,300 and an Mw / Mn ratio of 1.8.

[0110] [Examples 1-5] <1st process> Under a nitrogen atmosphere, 14.9 g (0.071 mol) of component (a), 3,3'-dithiodipropionic acid (manufactured by Sakai Chemical Industry Co., Ltd., trade name: DTDPA), 20.0 g (0.071 mol) of component (b), monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemicals, Ltd., trade name MA-DGIC), 1.318 g (0.0071 mol) of ethyltriphenylphosphonium bromide (manufactured by Hokko Chemical Industry Co., Ltd.), and 122.57 g of propylene glycol monomethyl ether were charged into a 300 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 6,700 and a polydispersity ratio of Mw / Mn of 5.4.

[0111] [ka]

[0112] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of cyclopentyl methyl ether (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the obtained purified polymer had a Mw of 10,000 and an Mw / Mn ratio of 3.8.

[0113] [Examples 1-6] <1st process> Under a nitrogen atmosphere, 16.5 g (0.071 mol) of phenobarbital (manufactured by Yatsushiro Pharmaceutical Co., Ltd.), component (a), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemicals, Ltd., product name MA-DGIC), component (b), 1.977 g (0.0053 mol) of tetrabutylphosphonium bromide (manufactured by Hokko Chemical Industry Co., Ltd.), and 153.87 g of propylene glycol monomethyl ether were charged into a 300 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 33,400 and an Mw / Mn ratio of 16.3.

[0114] [ka]

[0115] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of isopropyl alcohol (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the purified polymer had a Mw of 46,200 and an Mw / Mn ratio of 10.5.

[0116] [Examples 1-7] <1st process> Under a nitrogen atmosphere, 8.24 g (0.071 mol) of fumaric acid (manufactured by Tokyo Chemical Industry Co., Ltd.), component (a), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemicals, Ltd., product name MA-DGIC), component (b), 1.617 g (0.0071 mol) of benzyltriethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and 122.57 g of propylene glycol monomethyl ether were charged into a 300 mL reaction flask to prepare a raw material solution with a solid content of 20% by mass. Next, this solution was heated under 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® 550A, Muromachi Technos Co., Ltd.) and an anion exchange resin (product name: Amberlite® 15JWET, Organo Co., Ltd.) were added in amounts equal to the solid content of the raw material solution. Ion exchange treatment was performed at room temperature for 4 hours to remove unreacted monomer components and the catalyst used in the reaction, and this was subjected to GPC measurement and the second step. GPC measurements revealed that the crude polymer had a Mw of 4,600 and an Mw / Mn ratio of 3.1.

[0117] [ka]

[0118] <Second process> 50 g of the crude polymer solution obtained in the first step was added over 30 minutes to 500 g of cyclopentyl methyl ether (10 times the amount of the reaction solution) adjusted to 25°C to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was dissolved again in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added over 30 minutes to 500 g of cyclopentyl methyl ether (10 times the amount of the reaction solution) to reprecipitate, and the mixture was stirred for a further 30 minutes. The resulting precipitate was filtered by suction 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. GPC measurements revealed that the obtained purified polymer had a Mw of 5,100 and an Mw / Mn ratio of 2.9.

[0119] <Decrease rate of low molecular weight components> In Examples 1-1 to 1-7, the effect of implementing the second step was investigated by comparing the content of low molecular weight components with an Mw of 1,000 or less in the crude polymer and the purified polymer. The content and reduction rate of low molecular weight components were calculated using 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 value obtained by integrating the region with a standard polystyrene (PS) equivalent of Mw 1,000 or less and dividing it by the integral value of the entire region was used to calculate the detection intensity. (2) Decrease rate of low molecular weight components The content of low molecular weight components obtained in (1) above was calculated using the following formula. [1 - (Low molecular weight component content of purified polymer ÷ Low molecular weight component content of crude polymer)] × 100 (mass%) The results are shown in Table 1.

[0120] [Table 1]

[0121] [2] Preparation of compositions for forming a resist underlayer film <Example 2-1> To 0.97 g of the purified polymer obtained in Example 1-1, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-2, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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.

[0124] <Example 2-4> To 0.97 g of the purified polymer obtained in Examples 1-2, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-3, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-3, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-4, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-4, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-5, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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.

[0130] <Example 2-10> To 0.97 g of the purified polymer obtained in Examples 1-5, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-6, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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.

[0132] <Example 2-12> To 0.97 g of the purified polymer obtained in Examples 1-6, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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 Examples 1-7, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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.

[0134] <Example 2-14> To 0.97 g of the purified polymer obtained in Examples 1-7, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 69.13 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare 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] <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 glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0137] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0138] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0139] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0140] <Comparative Example 1-6> To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-3, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0141] <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 glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0142] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0143] <Comparative Example 1-9> To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-5, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0144] <Comparative Example 1-10> To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-5, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0145] <Comparative Example 1-11> To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-6, 0.24 g of tetramethoxymethyl glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0146] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare the solution. Subsequently, 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.

[0147] <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 glycoluryl (Nippon Scitec Industries Co., Ltd., trade name: POWDERLINK® 1174), 0.024 g of p-phenolsulfonic acid (Tokyo Chemical Industries Co., Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare the solution. Subsequently, 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.

[0148] <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 glycoluryl (Nippon Scitec Industries, Ltd., trade name: POWDERLINK® 1174), 0.024 g of 5-sulfosalicylic acid (Tokyo Chemical Industries, Ltd.), 65.24 g of propylene glycol monomethyl ether, and 29.63 g of propylene glycol monomethyl ether acetate were added to prepare a solution. Subsequently, 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.

[0149] Tables 2 and 3 below list the polymers and acid catalysts used in Examples 2-1 to 2-14 and Comparative Examples 1-1 to 1-14. The abbreviations listed in Table 1 are as follows: PSA: p-phenol sulfonic acid 5-SSA: 5-sulfosalicylic acid

[0150] [Table 2]

[0151] [Table 3]

[0152] <Measurement of sublimation volume> The resist underlayer film formation compositions prepared in Examples 2-1 to 2-14 and Comparative Examples 1-1 to 1-14 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 formation composition was placed in a sublimation volume measuring device with an integrated hot plate (see International Publication No. 2007 / 111147) and baked for 120 seconds. The sublimated material was collected on a QCM (Quartz Crystal Microbalance) sensor, i.e., a quartz crystal oscillator with electrodes formed on it. The QCM sensor can measure minute mass changes by utilizing the property that when sublimated material adheres to the surface (electrodes) of the quartz crystal oscillator, the frequency of the quartz crystal oscillator changes (decreases) according to the mass of the sublimated material.

[0153] The detailed measurement procedure is as follows: The hot plate of the sublimation volume measuring device is heated to 205°C, and the pump flow rate is set to 1 m³. 3 The timer was set to / s, and the device was left unattended for the first 60 seconds to stabilize. Immediately thereafter, the wafer coated with the resist underlayer was quickly placed onto the hot plate through the slide opening, and the sublimated material was collected from 60 seconds to 120 seconds (60 seconds). The initial thickness of the resist underlayer formed on the wafer was 35 nm.

[0154] Furthermore, the flow attachment (detection part) connecting the QCM sensor and the collection funnel of the sublimation volume measuring device described above was used without a nozzle. As a result, the airflow flows in without being restricted from the flow path (diameter: 32 mm) of the chamber unit, which is 30 mm away from the sensor (quartz oscillator). In addition, the QCM sensor used a material mainly composed of silicon and aluminum (AlSi) as electrodes, with a quartz oscillator diameter (sensor diameter) of 14 mm, an electrode diameter on the surface of the quartz oscillator of 5 mm, and a resonant frequency of 9 MHz.

[0155] The obtained frequency changes were converted to grams from the eigenvalues ​​of the quartz crystal oscillator used for measurement, and the amount of sublimation in one wafer coated with the resist underlayer was determined. The results are shown in Table 4. In Table 4, X represents a film formed using a composition containing the crude polymer synthesized in the first step, and Y represents a film formed using a composition containing the purified polymer purified in the second step. Table 4 also shows the effect of the presence or absence of a reprecipitation purification step on the sublimated product.

[0156] [Table 4]

[0157] Based on the above, the results showed that the resist underlayer films obtained from a resist underlayer film formation composition containing a purified polymer with a reduced content of low molecular weight components (Examples 2-1 to 2-14) exhibited less sublimation compared to the resist underlayer films obtained from a resist underlayer film formation composition containing a crude polymer (Comparative Examples 1-1 to 1-14).

Claims

1. A resist underlayer film forming composition comprising a polymer having repeating units represented by the following formula (1-1) or (1-3), and an organic solvent, wherein the content of low molecular weight components with a weight-average molecular weight of 1,000 or less in the polymer is 10% by mass or less, The above polymer is prepared by blending any monomer represented by the following formula (a) and a monomer represented by the following formula (b) in a molar ratio of (a):(b) = 1:1.21 to 1:1, reacting them in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt at 60 to 150°C to obtain a crude polymer solution, and then performing an ion exchange treatment by adding a cation exchange resin and an anion exchange resin to the obtained crude polymer solution. The above organic solvent is at least one 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. The above quaternary phosphonium salt is selected from the group consisting of 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. The above quaternary ammonium salt is selected from the group consisting of 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, and methyltrioctylammonium chloride. The first step is to synthesize the crude polymer, The process includes mixing the solution containing the crude polymer obtained in the first step with a poor solvent to precipitate the purified polymer and filter it off. The above poor solvent is at least one selected from the group consisting of diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropyl alcohol. A resist underlayer film forming composition, wherein in the second step, 54.6% by mass or more of low molecular weight components with a weight-average molecular weight of 1,000 or less are removed from the crude polymer. 【Chemistry 1】 【Chemistry 2】

2. Furthermore, the composition for forming a resist underlayer film according to claim 1, further comprising a crosslinking agent.

3. Furthermore, the resist underlayer film forming composition according to claim 1 or 2, further comprising an acid catalyst.

4. A resist underlayer film obtained from the resist underlayer film forming composition according to any one of claims 1 to 3.

5. A polymer having repeating units represented by the following formula (1-1) or (1-3), wherein the content of low molecular weight components with a weight-average molecular weight of 1,000 or less in the polymer is 10% by mass or less. The process involves mixing any monomer represented by formula (a) below with a monomer represented by formula (b) below in a molar ratio of (a):(b) = 1:1.21 to 1:1, reacting them in an organic solvent in the presence of a quaternary phosphonium salt or a quaternary ammonium salt at 60 to 150°C to obtain a crude polymer solution, and then performing an ion exchange treatment by adding a cation exchange resin and an anion exchange resin to the obtained crude polymer solution. The above organic solvent is at least one 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. The above quaternary phosphonium salt is selected from the group consisting of 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. The above quaternary ammonium salt is selected from the group consisting of 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, and methyltrioctylammonium chloride. The first step is to synthesize the crude polymer, The process includes mixing the solution containing the crude polymer obtained in the first step with a poor solvent to precipitate the purified polymer and filter it off. The above poor solvent is at least one selected from the group consisting of diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropyl alcohol. A polymer from which 54.6% or more by mass of low molecular weight components with a weight-average molecular weight of 1,000 or less has been removed by the second step. 【Transformation 3】 【Chemistry 4】

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