Composition for forming a resist underlayer film

Abstract

As a composition for forming a photoresist underlayer film that can reduce the amount of sublimation products derived from low molecular weight components such as oligomers, for example, a composition for forming a photoresist underlayer film is provided, comprising a polymer having repeating units represented by the following formula (1-1) and an organic solvent, wherein the content of low molecular weight components with a weight average molecular weight of 1000 or less in the polymer is 10% by mass or less.

Description

Technical Field

[0001] The present invention relates to compositions for forming a resist underlayer film, and more specifically, to compositions for forming a resist underlayer film containing a condensation polymer, wherein the condensation polymer is obtained by reacting a monomer containing a pyrimidine trione structure or a triazine trione structure. Background Technology

[0002] Conventionally, a known method for manufacturing the aforementioned condensation polymers involves reacting monoallyl diglycidyl isocyanuric acid with 5,5-diethylbarbituric acid. For example, in Synthesis Example 1 of Patent Documents 1 and 2, it is described that the above-mentioned compounds and benzyltriethylammonium chloride were dissolved in propylene glycol monomethyl ether and reacted at 130°C for 24 hours to obtain a solution containing a polymer with a weight-average molecular weight of 6800.

[0003] Patent Documents 1 and 2 also describe the preparation of an antireflective film forming composition or an EUV lithography resist underlayer film forming composition using a solution containing the aforementioned polymer.

[0004] Polymers obtained through chemical synthesis are typically aggregates of molecules with varying molecular weights (degrees of polymerization). The molecular weight of such polymers is expressed as 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 its average molecular weight and the higher its polydispersity index (Mw / Mn).

[0005] However, the polymers obtained using the synthesis methods described in Patent Documents 1 and 2 contain a large amount of low molecular weight components. When the antireflective film forming composition or the EUV lithography resist underlayer forming composition prepared using this polymer is coated onto a substrate and baked to form a film, a significant amount of sublimation from these low molecular weight components is generated. This sublimation becomes a cause of contamination inside the baking apparatus, specifically, it contaminates the top plate directly above the heating plate on which the substrate is placed and the exhaust pipe. When the baking apparatus is contaminated with sublimation, it is necessary to clean the interior of the apparatus, and from the viewpoint of improving productivity, it is strongly recommended to reduce the amount of sublimation generated.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2005 / 098542

[0009] Patent Document 2: International Publication No. 2013 / 018802 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The present invention was made in view of the above circumstances, and its object is to provide a composition for forming a resist underlayer film that can reduce the amount of sublimation products derived from low molecular weight components such as oligomers.

[0012] Methods for solving problems

[0013] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by making the content of low molecular weight components with a weight average molecular weight of 1000 or less in the polymer contained in the composition for forming a photoresist underlayer film 10% by mass or less, the amount of sublimation generated during the formation of the photoresist underlayer film can be reduced, thereby completing the present invention.

[0014] That is, the present invention provides the following composition for forming a resist underlayer film.

[0015] 1. A composition for forming a resist underlayer film, comprising a polymer having repeating units represented by the following formula (1) and an organic solvent, wherein the content of a low molecular weight component having a weight average molecular weight of 1000 or less in the polymer is 10% by mass or less.

[0016] [Chemistry 1]

[0017]

[0018] In formula (1), A independently represents a hydrogen atom, a methyl atom, or an ethyl atom, and Q... 1 and Q 2 Representation (2) or (3),

[0019] [Chemistry 2]

[0020]

[0021] [In the formula, Q] 3 The denotes alkylene, alkenylene, phenylene, naphthylene, or anthraceneylene, which may contain thioether or disulfide bonds and have 1 to 10 carbon atoms, and which may contain phenylene, naphthylene, or anthraceneylene, which may be substituted by groups selected from alkyl, phenyl, halogen, alkoxy, nitro, cyano, hydroxyl, and alkylthio, which may contain 1 to 6 carbon atoms; B independently represents a single bond or an alkylene with 1 to 5 carbon atoms; n independently represents 0 or 1; m independently represents 0 or 1; X represents formula (4) or formula (5):

[0022] [Chemistry 3]

[0023]

[0024] (where R is in the formula) 1 Independently representing hydrogen atoms, halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 3 to 6 carbon atoms, benzyl groups, or phenyl groups, wherein the alkyl and alkenyl groups may be substituted with halogen atoms, hydroxyl groups, or cyano groups, wherein the hydrogen atom on the aromatic ring of the benzyl group may be substituted with a hydroxyl group, and wherein the phenyl group may be substituted with a group selected from alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms, and 2 R groups. 1 They can bond with each other to form rings with 3 to 6 carbon atoms; R 2 This 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, wherein the phenyl group may be substituted by a group selected from alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms. Wherein, Q 1 and Q 2 At least one of them contains the structure represented by equation (3).

[0025] }

[0026] 2. The composition according to claim 1 for forming a resist underlayer film, further comprising a crosslinking agent.

[0027] 3. The composition for forming a resist underlayer film according to 1 or 2, further comprising an acid catalyst.

[0028] 4. A photoresist underlayer film, which is obtained from the composition according to any one of 1 to 3 for forming a photoresist underlayer film.

[0029] 5. A polymer having repeating units represented by the following formula (1), wherein the content of a low molecular weight component with a weight average molecular weight of 1000 or less in the polymer is 10% by mass or less.

[0030] [Chemistry 4]

[0031]

[0032] In formula (1), A independently represents a hydrogen atom, a methyl atom, or an ethyl atom, and Q... 1 and Q 2 Representation (2) or (3),

[0033] [Chemistry 5]

[0034]

[0035] [In the formula, Q] 3The denotes represent alkylene groups of 1 to 10 carbon atoms, alkenyl groups of 2 to 10 carbon atoms, phenylene groups, naphthylene groups, or anthracene groups, which may contain thioether or disulfide bonds. The aforementioned phenylene, naphthylene, and anthracene groups can be independently substituted by groups selected from alkyl, phenyl, halogen, alkoxy, nitro, cyano, hydroxyl, and alkylthio groups of 1 to 6 carbon atoms; B independently represents a single bond or an alkylene group of 1 to 5 carbon atoms; n independently represents 0 or 1; m independently represents 0 or 1; X represents formula (4) or formula (5):

[0036] [Chemistry 6]

[0037]

[0038] (where R is in the formula) 1 Independently representing hydrogen atoms, halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 3 to 6 carbon atoms, benzyl groups, or phenyl groups, wherein the alkyl and alkenyl groups may be substituted with halogen atoms, hydroxyl groups, or cyano groups, wherein the hydrogen atom on the aromatic ring of the benzyl group may be substituted with a hydroxyl group, and wherein the phenyl group may be substituted with a group selected from alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms, and 2 R groups. 1 They can bond with each other to form rings with 3 to 6 carbon atoms; R 2 This 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, wherein the phenyl group may be substituted by a group selected from alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms. Wherein, Q 1 and Q 2 At least one of them contains the structure represented by equation (3).

[0039] Invention Effects

[0040] If the composition for forming a resist underlayer film according to the present invention is used, the frequency of sublimation during the formation of the resist underlayer film can be reduced, thereby helping to improve the productivity of the resist underlayer film. Detailed Implementation

[0041] The composition for forming a resist underlayer film according to the present invention is characterized in that it comprises a polymer having repeating units represented by the following formula (1) and an organic solvent, wherein the content of a low molecular weight component (hereinafter referred to as Mw) of 1000 or less in the polymer is 10% by mass or less. It should be noted that, in the present invention, a low molecular weight component means an oligomer or other polymer having repeating units represented by formula (1) with a Mw not exceeding 1000, but excluding unreacted monomer components and other components such as catalysts used in the polymerization reaction. Furthermore, in the present invention, Mw is a polystyrene conversion value determined by gel permeation chromatography (GPC).

[0042] [Chemistry 7]

[0043]

[0044] In the formula, A independently represents a hydrogen atom, a methyl atom, or an ethyl atom, and Q... 1 and Q 2 Represented by equation (2) or equation (3).

[0045] [Chemistry 8]

[0046]

[0047] In the formula, Q 3 This indicates that the alkylene group (1-10 carbon atoms), the alkenyl group (2-10 carbon atoms), the phenylene group, the naphthylene group, or the anthracene group may contain a thioether bond or a disulfide bond. The aforementioned phenylene, naphthylene, and anthracene groups may be independently substituted by groups selected from alkyl, phenyl, halogen atoms, alkoxy, nitro, cyano, hydroxyl, and alkylthio groups (1-6 carbon atoms).

[0048] B independently represents a single bond or an alkylene group having 1 to 5 carbon atoms.

[0049] n is 0 or 1 independently.

[0050] m is independently 0 or 1.

[0051] X is a group represented by formula (4) or formula (5).

[0052] [Chemistry 9]

[0053]

[0054] In the formula, R 1Independently representing hydrogen atoms, halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 3 to 6 carbon atoms, benzyl groups, or phenyl groups. The alkyl and alkenyl groups can be substituted with halogen atoms, hydroxyl groups, or cyano groups. The hydrogen atom on the aromatic ring of the benzyl group can be substituted with a hydroxyl group. The phenyl group can be substituted with a group selected from alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms, with two R groups. 1 They can bond with each other to form rings with 3 to 6 carbon atoms.

[0055] R 2 This refers to 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 aforementioned phenyl group may be substituted with a group selected from alkyl groups 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 hydroxyl group, and an alkylthio group having 1 to 6 carbon atoms.

[0056] Among them, Q 1 and Q 2 At least one of them contains the structure represented by equation (3).

[0057] As an alkylene group having 1 to 10 carbon atoms, it can be linear, branched, or cyclic. Examples include methylene, ethylene, propylene, pentamethylene, cyclohexylene, 2-methylpropylene, and 1-methylethoxyyl. Furthermore, as an alkylene group having 1 to 10 carbon atoms containing a thioether bond or a disulfide bond, examples include alkylene groups containing a thioether bond or a disulfide bond represented by the following formula.

[0058] [Chemistry 10]

[0059]

[0060] (In the formula, * represents the bonding end.)

[0061] As an alkenyl group with 2 to 10 carbon atoms, it can be straight-chain, branched, or cyclic. Examples include vinylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octeneylene, and nonenylene.

[0062] As an alkyl group having 1 to 6 carbon atoms, it can be any of the following: straight-chain, branched, or cyclic. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopentyl, and cyclohexyl.

[0063] Alkoxy groups having 1 to 6 carbon atoms can be linear, branched, or cyclic. Examples include methoxy, ethoxy, isopropoxy, n-pentoxy, n-hexoxy, and cyclohexoxy.

[0064] As an alkylthio group having 1 to 6 carbon atoms, it can be any of the following: linear, branched, or cyclic. Examples include methylthio, ethylthio, isopropylthio, n-pentylthio, and cyclohexylthio.

[0065] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0066] As 2 R 1 The rings formed by bonding with 3 to 6 carbon atoms include cyclobutane rings, cyclopentane rings, and cyclohexane rings.

[0067] In this invention, Mw is the converted value of polystyrene determined by gel permeation chromatography (GPC).

[0068] As a repeating unit represented by equation (1), for example, repeating units represented by the following equations (1-1) to (1-4) can be exemplified, but are not limited to these.

[0069] [Chemistry 11]

[0070]

[0071] The content of low molecular weight components with a Mw of 1000 or less in the above polymer is 10% by mass or less, but from the viewpoint of further reducing the amount of sublimation generated, it is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0072] The Mw of the above-mentioned polymer is preferably 1,000 to 200,000, more preferably 2,000 to 100,000, even more preferably 3,000 to 50,000, even more preferably 4,000 to 30,000, and most preferably 5,000 to 20,000. The polydispersity index 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 below).

[0073] The polymer described above, with reduced content of low molecular weight components, can be synthesized by the following method comprising step 1 and step 2. It should be noted that, in the following description, "crude polymer" refers to the polymer synthesized through step 1, while "refined polymer" refers to the polymer obtained from a solution containing the aforementioned crude polymer through step 2.

[0074] <Step 1>

[0075] The first step is as follows: in an organic solvent, in the presence of a quaternary phosphonium salt or a quaternary ammonium salt, a monomer represented by formula (a) below (hereinafter, sometimes abbreviated as component (a)) and a monomer represented by formula (b) below (hereinafter, sometimes abbreviated as component (b)) are reacted to synthesize a crude polymer having repeating units represented by formula (1) below.

[0076] [Chemistry 12]

[0077]

[0078] In the formula, A and Q 1 and Q 2 Same as above.

[0079] The following compounds can be listed as specific examples of component (a).

[0080] As one of the Q 1 Compounds that are groups represented by formula (2), for example, diglycidyl ester compounds and diglycidyl ether compounds can be listed.

[0081] Examples of diglycidyl ester compounds include, for example: diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl phthalate, 2,5-dimethyl diglycidyl terephthalate, 2,5-diethyl diglycidyl terephthalate, 2,3,5,6-tetrachlorodiglycidyl terephthalate, 2,3,5,6-tetrabromodiglycidyl terephthalate, and 2-nitrodiglycidyl terephthalate. 2,3,5,6-Tetrafluoroterephthalic 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 Diglycidyl phthalate, 2-methoxyisophthalic acid diglycidyl phthalate, 5-phenylisophthalic acid diglycidyl phthalate, 3-nitrophthalic acid diglycidyl phthalate, 3,4,5,6-tetrachlorophthalic acid diglycidyl phthalate, 4,5-dichlorophthalic acid diglycidyl phthalate, 4-hydroxyphthalic acid diglycidyl phthalate, 4-nitrophthalic acid diglycidyl phthalate, 4-methylphthalic acid diglycidyl phthalate, 3,4,5,6 - Diglycidyl tetrafluorophthalate, diglycidyl 2,6-naphthalenedicarboxylate, diglycidyl 1,2-naphthalenedicarboxylate, diglycidyl 1,4-naphthalenedicarboxylate, diglycidyl 1,8-naphthalenedicarboxylate, anthracene-9,10-dicarboxylic acid diglycidyl ester, diglycidyl 1,2-cyclohexanedicarboxylic acid diglycidyl ester, dithiodiglycolic acid diglycidyl ester, 2,2'-thiodiglycolic acid diglycidyl ester and diglycolic acid diglycidyl ester.

[0082] Examples of diglycidyl ether compounds include, for example: 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-naphthol diglycidyl ether.

[0083] As one of the Q 1 Compounds that are groups represented by formula (3), for example, diglycidyl barbituric acid compounds and diglycidyl isocyanuric acid compounds can be listed.

[0084] Examples of diglycidyl barbituric acid compounds include, for example: 1,3-diglycidyl-5,5-diethyl barbituric acid, 1,3-diglycidyl-5-phenyl-5-ethyl barbituric acid, 1,3-diglycidyl-5-ethyl-5-isopentyl barbituric acid, 1,3-diglycidyl-5-allyl-5-isobutyl barbituric acid, 1,3-diglycidyl-5-allyl-5-isopropyl barbituric acid, 1,3-diglycidyl-5-β-bromoallyl-5-sec-butyl barbituric acid, 1 3-Diglycidyl-5-ethyl-5-(1-methyl-1-butenyl)barbituric acid, 1,3-diglycidyl-5-isopropyl-5-β-bromoallylbarbituric 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 ester, and 1,3-diglycidyl-5-ethyl-5-n-butylbarbituric acid.

[0085] Examples of diglycidyl isocyanuric acid compounds include, for example, 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 monobromo diglycidyl isocyanuric acid, monoallyl isocyanuric acid diglycidyl ester, monomethyl isocyanuric acid diglycidyl ester, etc.

[0086] The following compounds can be listed as specific examples of component (b).

[0087] As one of the Q 2 Compounds that are groups represented by formula (2), for example, dicarboxylic acid compounds can be listed.

[0088] Examples of dicarboxylic acid compounds include, for example: 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, 4,5-dichlorophthalic 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-dimethyldipropionic acid, and 3,3'-dithiodipropionic acid.

[0089] As one of the Q 2 Compounds that are groups represented by formula (3), for example, barbituric acid compounds and isocyanate compounds can be listed.

[0090] Examples of barbituric acid compounds include, for example: barbituric acid, 5,5-dimethylbarbituric acid, 5,5-diethylbarbituric acid (also known as barbiturate), 5-methyl-5-ethylbarbituric acid, 5,5-diallylbarbituric acid (also known as allobarbiturate), 5-ethyl-5-phenylbarbituric acid (also known as phenobarbiturate), 5-ethyl-5-isopentylbarbituric acid (also known as isopentylbarbiturate), 5,5-diallylmalonic acid, 5-ethyl-5-isopentylbarbituric acid, 5-allyl... 5-O-5-isobutylbarbituric 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-n-butylbarbituric acid.

[0091] Examples of isocyanuric acid compounds include, for example, monoallyl isocyanuric acid, monomethyl isocyanuric acid, monoethyl isocyanuric acid, monopropyl isocyanuric acid, monoisopropyl isocyanuric acid, monophenyl isocyanuric acid, monobenzyl isocyanuric acid, and monochloroisocyanuric acid.

[0092] With regard to components (a) and (b) exemplified above, it is generally possible to combine any one of the compounds selected from each, but this is not a limitation; multiple compounds may be used from either or both of components (a) and (b). Specifically, at least one of components (a) and (b) comprises a compound having a skeleton selected from barbituric acid and isocyanuric acid.

[0093] The following compounds can be cited as examples of (a) components that can be preferably used in this invention, but are not limited to these.

[0094] [Chemistry 13]

[0095]

[0096] In addition, the following compounds can be cited as examples of (b) components that can be preferably used in this invention, but are not limited to these.

[0097] [Chemistry 14]

[0098]

[0099] There are no particular limitations on the mixing ratio (molar ratio) of component (a) and component (b). From the viewpoint of suppressing the residue of unreacted component (a) with epoxy groups, it is preferable to make component (a) and component (b) equimolar, or to make component (b) in excess relative to component (a), and more preferably (a):(b) = 1:1.21 to 1:1. By keeping the above mixing ratio below the upper limit, it is easy to obtain a polymer with the target Mw.

[0100] Examples of quaternary phosphonium salts include, 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. In this invention, ethyltriphenylphosphonium bromide and tetrabutylphosphonium bromide are preferred.

[0101] 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 this invention, benzyltriethylammonium chloride is preferably used.

[0102] Regarding the mixing amount of the quaternary phosphonium salt and quaternary ammonium salt mentioned above, there is no particular limitation as long as the amount allows the reaction to proceed, but it is preferably 0.1 to 10.0% relative to the molar number of component (a), more preferably 1.0 to 5.0%.

[0103] As the organic solvent used in the first step, any organic solvent that does not affect the reaction can be used. Examples include: benzene, toluene, xylene, ethyl lactate, butyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, and N-methylpyrrolidone. These solvents can be used alone or in combination of two or more. In this invention, propylene glycol monomethyl ether is preferred if the use of the composition of the final polymer is taken into consideration.

[0104] The amount of organic solvent used can be appropriately set according to the types and amounts of the above-mentioned components, and there is no particular limitation thereto. In this invention, if the reaction is to proceed efficiently, the total solid content concentration of the above-mentioned components is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. It should be noted that the solid content of the solution referred to herein means the components that make up the solution other than the solvent.

[0105] The reaction temperature for the first step is typically below 200°C. Considering the boiling point of the organic solvent used, it is preferably below 150°C, and more preferably below 130°C. There is no particular limitation on the lower limit of the reaction temperature, but if the condensation reaction of components (a) and (b) is to be completed rapidly, it is preferably above 50°C, and more preferably above 60°C. Furthermore, reflux can be performed during heating.

[0106] The reaction time depends on the reaction temperature and the reactivity of the raw materials, and cannot be generalized, but it is usually about 1 to 48 hours. When the reaction temperature is 60 to 130°C, it is about 15 to 30 hours.

[0107] <Step 2>

[0108] The second step is as follows: a solution containing the crude polymer obtained in the first step (hereinafter referred to as the crude polymer solution) is mixed with a poor solvent, and the crude polymer having repeating units represented by formula (1) is precipitated and filtered. This second step removes low molecular weight components contained in the crude polymer. Here, the crude polymer solution can be the reaction solution obtained in the first step directly, or it can be a solution obtained by dissolving the crude polymer separated by appropriate means such as drying in a suitable solvent. In the latter case, the organic solvent used in the first step can be used as the solvent.

[0109] As a poor solvent used in the second step, solvents with low polymer solubility and capable of dissolving low molecular weight components can be used, such as diethyl ether, cyclopentyl methyl ether, diisopropyl ether, and isopropanol. These can be used individually or in combination of two or more. In this invention, isopropanol is preferred.

[0110] In this invention, there is no particular limitation on the mixing order when mixing the crude polymer solution and the undesirable solvent. The crude polymer solution can be added to the undesirable solvent, or the undesirable solvent can be added to the crude polymer solution. However, if the removal of more low molecular weight components is considered, the method of adding the crude polymer solution to the undesirable solvent is preferred.

[0111] In addition, when mixing the two, they can be added slowly by dripping or by adding all the ingredients at once. However, if the goal is to reduce the content of low molecular weight components in the refined polymer, the method of adding slowly by dripping is preferred.

[0112] Regarding the amount of undesirable solvent relative to the crude polymer solution, there is no particular limitation as long as the amount does not cause the low molecular weight components to precipitate and allows the polymer to precipitate sufficiently. However, the amount is preferably 2 to 30 times the total mass of the crude polymer solution, more preferably 5 to 20 times the mass, and even more preferably 5 to 15 times the mass.

[0113] Regarding the temperature during mixing, it is not particularly limited as long as it is set appropriately within the range from the melting point to the boiling point of the solvent used, but it is usually possible to set it to around -20 to 50°C. If the ease of precipitation formation and operability are taken into consideration, it is preferred to set it to 0 to 50°C, and more preferably to set it to 0 to 30°C.

[0114] As a preferred method for the above mixing operation, for example, the following approach can be adopted: when slowly adding a crude polymer solution with a total solids concentration of 5 to 50% by mass to a poor solvent at a ratio of 5 to 20 times by mass, each 50g of crude polymer solution is added slowly over 15 minutes to 1 hour. However, this method is not limited to this approach.

[0115] After the mixing process is complete, in order to remove more low molecular weight components, the mixture can be stirred continuously for a given time. In this case, the stirring time is preferably 10 minutes to 2 hours, and more preferably 15 minutes to 1 hour.

[0116] In addition, in order to further reduce the polydispersity index of the polymer, the precipitate obtained by filtration in the second step can be dissolved again in the organic solvent used in the first step. After mixing the resulting solution with the aforementioned undesirable solvent, the process of filtration of the generated precipitate is carried out.

[0117] Through the second step described above, more than 30% by mass, preferably more than 40% by mass, more preferably more than 70% by mass, and even more preferably more than 90% by mass, of the low molecular weight components contained in the crude polymer can be removed, ultimately obtaining a polymer (refined polymer) with a low molecular weight component content of less than 10% by mass, preferably less than 5% by mass, more preferably less than 3% by mass, and even more preferably less than 1% by mass.

[0118] As an organic solvent, any solvent capable of dissolving the solid components can be used without particular restriction. In particular, since the composition for forming the resist underlayer film involved in this invention is used in a homogeneous solution state, it is recommended to use solvents commonly used in photolithography processes in conjunction with it, taking into account its coating performance.

[0119] Examples of organic solvents mentioned above 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, cyclohexanone, cycloheptanone, 4-methyl-2-pentanol, and methyl 2-hydroxyisobutyrate. Ethyl 2-hydroxyisobutyrate, ethyl ethoxylate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These organic solvents can be used alone or in combination of two or more.

[0120] The solid content concentration of the composition for forming the resist underlayer film of the present invention is appropriately set taking into account the viscosity and surface tension of the composition, the thickness of the manufactured film, etc., but is generally 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. It should be noted that the solid content of the composition referred to herein means the components other than the solvent contained in the composition for forming the resist underlayer film of the present invention.

[0121] Without impairing the effects of the present invention, the composition of the present invention for forming a resist underlayer film may contain optional components 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.

[0122] There are no particular limitations on the crosslinking agent, but compounds having at least two crosslinking groups within the molecule are preferred. For example, melamine-based compounds and substituted urea-based compounds having crosslinking groups such as hydroxymethyl and methoxymethyl can be listed. Specifically, compounds such as methoxymethylated glycourea or methoxymethylated melamine, for example, tetramethoxymethylglycourea, tetrabutoxymethylglycourea, or hexamethoxymethylmelamine. In addition, compounds such as tetramethoxymethylurea and tetrabutoxymethylurea can also be listed. These crosslinking agents can induce a crosslinking reaction through self-condensation. In addition, they can undergo a crosslinking reaction with hydroxyl groups in polymers having the structure represented by formula (1). Moreover, through such a crosslinking reaction, the underlying film formed becomes strong. Moreover, it becomes an underlying film with low solubility relative to organic solvents. These crosslinking agents can be used alone or in combination of two or more.

[0123] When the composition for forming the resist underlayer film described above contains a crosslinking agent, its content varies depending on the organic solvent used, the underlying 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% by mass of the solid component, more preferably 0.1 to 40% by mass, and even more preferably 0.5 to 30% by mass. These crosslinking agents sometimes cause crosslinking reactions through self-condensation, but when crosslinking substituents are present in the polymer of the present invention, crosslinking reactions can occur with these crosslinking substituents.

[0124] Examples of acid catalysts include: sulfonic acid compounds such as p-phenolsulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, and pyridine-p-toluenesulfonate; carboxylic acid compounds such as salicylic acid, 5-sulfosalicylic acid, citric acid, benzoic acid, and hydroxybenzoic acid; acid compounds that generate acids through heat or light, such as 2,4,4,6-tetrabromocyclohexadienone, benzoin toluenesulfonate, 2-nitrobenzyl toluenesulfonate, p-trifluoromethylbenzenesulfonate-2,4-dinitrobenzyl ester, phenyl-bis(trichloromethyl)-triazine, and N-hydroxysuccinimide trifluoromethanesulfonate; iodonium salt-based acid-generating agents such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt-based acid-generating agents such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium trifluoromethanesulfonate. In this invention, sulfonic acid compounds and carboxylic acid compounds are preferably used among these compounds. Furthermore, these acid catalysts can be used alone or in combination of two or more.

[0125] When the composition for forming the resist underlayer film contains an acid catalyst, from the viewpoint of sufficiently promoting the crosslinking reaction, its content is preferably 0.0001 to 20% by mass of the solid component, more preferably 0.01 to 15% by mass, and even more preferably 0.1 to 10% by mass.

[0126] Surfactants are added to further improve the coating properties of semiconductor substrates. Examples of surfactants include: polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene hexadecyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkyl aryl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; polyoxyethylene / polyoxypropylene block copolymers; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate; and polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monostearate. Nonionic surfactants such as palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate, etc., which are polyoxyethylene sorbitan fatty acid esters; EFTOP [registered trademark] EF301, EF303, EF352 (manufactured by Mitsubishi Materials Electronics & Chemicals Co., Ltd.), MEGAFACE [registered trademark] F171, F173, R-30, R-30N, R-40, R-40-LM (manufactured by DIC Co., Ltd.), perfluoroalkyl esters FC430, FC431 (manufactured by 3M Japan Co., Ltd.), Asahi Fluoropolymer surfactants such as Guard (registered trademark) AG710, Surfluon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC Corporation), and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used individually or in combination of two or more.

[0127] When the composition for forming the resist underlayer film contains a surfactant, from the viewpoint of improving the coatability of the semiconductor substrate, its content is preferably 0.0001 to 10% by mass of the solid component, more preferably 0.01 to 5% by mass.

[0128] As light absorbers, commercially available light absorbers listed in "Technology and Markets of Industrial Pigments" (CMC publication) and "Dye Handbook" (edited by the Organic Synthetic Chemistry Society) are preferred, 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; CI Fluorescent Brightener 112, 135 and 163; CI Solvent Orange 2 and 45; CI Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49; CI Pigment Green 10; CI Pigment Brown 2, etc.

[0129] When the light absorber is present, its content is generally preferably 0.1 to 10% by mass of the solid component, more preferably 0.1 to 5% by mass.

[0130] The purpose of adding rheology modifiers is primarily to improve the flowability of the composition used to form the resist underlayer film, especially during the baking process, to enhance the uniformity of the resist underlayer film thickness and improve the filling ability of the composition used to form the resist underlayer film into the pores. Examples of rheology modifiers include: phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives such as di-n-butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyl decyl adipate; maleic acid derivatives such as di-n-butyl maleate, diethyl maleate, and dinonyl maleate; oleic acid derivatives such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate; and stearic acid derivatives such as n-butyl stearate and glyceryl stearate.

[0131] When the composition for forming the resist underlayer contains a rheology modifier, from the viewpoint of appropriately improving the flowability of the composition for forming the resist underlayer, its content is preferably 0.001 to 30% by mass of the solid components, more preferably 0.001 to 10% by mass.

[0132] The purpose of adding adhesive additives is primarily to improve the adhesion between the substrate or resist and the composition used to form the underlying resist film, especially during development to prevent the resist from peeling off. Examples of adhesive additives include: chlorosilanes such as trimethylchlorosilane, dimethylhydroxymethylchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylhydroxymethylethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane; and alkoxysilanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylamine. Silazanes such as methylsilylimidazolium; silanes such as hydroxymethyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-epoxypropoxypropyltrimethoxysilane; heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazolium, and mercaptopyrimidine; ureas such as 1,1-dimethylurea and 1,3-dimethylurea; and thiourea compounds.

[0133] When the composition for forming the resist underlayer film contains a rheology modifier, from the viewpoint of further improving the adhesion between the semiconductor substrate or the resist and the underlayer film, its content is preferably 0.01 to 5% by mass of the solid component, more preferably 0.1 to 2% by mass.

[0134] The following describes a photoresist underlayer film manufactured using the composition for forming a photoresist underlayer film according to the present invention, a photoresist patterning method, and a method for manufacturing a semiconductor device.

[0135] The lower layer film involved in this invention can be manufactured by coating the above-mentioned composition for forming a resist lower layer film onto a semiconductor substrate and then firing it.

[0136] 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.

[0137] Alternatively, semiconductor substrates with inorganic films formed on their surfaces can also be used. Examples of such inorganic films include: polycrystalline silicon films, silicon oxide films, silicon nitride films, BPSG (Boro-Phospho Silicate Glass) films, titanium nitride films, titanium oxynitride films, tungsten films, gallium nitride films, and gallium arsenide films. These inorganic films can be formed on the semiconductor substrate using methods such as: ALD (Atomic Layer Deposition), CVD (Chemical Vapor Deposition), reactive sputtering, ion plating, vacuum evaporation, and spin coating (SOG).

[0138] On such a semiconductor substrate, the composition of the present invention for forming a photoresist underlayer film is coated using a suitable coating method such as a spin coater or a coating machine. Then, the photoresist underlayer film is formed by firing using a heating device such as a heating plate. The firing conditions are appropriately selected from a firing temperature of 100–400°C and a firing time of 0.3–60 minutes. Preferably, the firing temperature is 120–350°C and the firing time is 0.5–30 minutes; more preferably, the firing temperature is 150–300°C and the firing time is 0.8–10 minutes. By keeping the firing temperature above the lower limit of the above range, the polymer can be fully crosslinked. On the other hand, by keeping the firing temperature below the upper limit of the above range, the photoresist underlayer film can be prevented from thermally decomposing, thus forming a good thin film.

[0139] Regarding the thickness of the resist underlayer film, for example, it is 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).

[0140] Next, a photoresist layer is formed on top of the photoresist underlayer film. The photoresist layer can be formed using known methods by coating a photoresist composition solution onto the underlayer film and then firing it.

[0141] As a photoresist, there are no particular limitations as long as it is sensitive to the light used for exposure. Both negative and positive photoresists can be used. Specific examples include: positive photoresists containing phenolic varnish resin and 1,2-naphthoquinone diazidesulfonate; chemically amplified photoresists containing binders and photoacid-generating agents having groups that increase the alkali dissolution rate of the photoresist through acid decomposition; chemically amplified photoresists containing low-molecular-weight compounds that increase the alkali dissolution rate of the photoresist through acid decomposition; alkali-soluble binders and photoacid-generating agents; and chemically amplified photoresists containing binders that increase the alkali dissolution rate of the photoresist through acid decomposition, low-molecular-weight compounds that increase the alkali dissolution rate of the photoresist through acid decomposition, and photoacid-generating agents. Commercially available products can be used as photoresists, such as: V146G manufactured by JSR Corporation, APEX-E manufactured by Shipley Corporation, PAR710 manufactured by Sumitomo Chemical Co., Ltd., AR2772 manufactured by Shin-Etsu Chemical Co., Ltd., and SEPR430. Additionally, fluorine-containing polymer-based photoresists 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.

[0142] Next, exposure is performed using a given mask. For example, an i-line, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet) or EB (electron beam) laser can be used for exposure.

[0143] Next, development is performed using a developer. In this way, for example, when using a positive photoresist, the photoresist in the exposed areas is removed, forming a photoresist pattern.

[0144] As the developer, an alkaline developer is used. For example, aqueous solutions of the following alkaline substances can be used: inorganic alkalines such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and 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; alkanolamines 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 alcohols such as isopropanol and nonionic surfactants can be added to the above-mentioned alkaline aqueous solutions. Quaternary ammonium salts are preferred, and tetramethylammonium hydroxide and choline are more preferred. In addition, surfactants can also be added to these developers. As for the developing conditions, an appropriate selection can be made from a developing temperature of 5 to 50°C and a developing time of 10 to 300 seconds.

[0145] Next, using the formed resist pattern as a mask, the underlying resist film is dry-etched. At this point, if the inorganic film is formed on the surface of the semiconductor substrate being used, the surface of the inorganic film is exposed; if the inorganic film is not formed on the surface of the semiconductor substrate being used, the surface of the semiconductor substrate is exposed.

[0146] Example

[0147] The present invention will now be described in detail with reference to embodiments and comparative examples, but the present invention is not limited to the embodiments described below.

[0148] [Determination of weight-average molecular weight Mw and polydispersity index Mw / Mn]

[0149] The Mw and Mw / Mn of the crude and refined polymers were calculated from the peaks of the chromatograms obtained by gel permeation chromatography (GPC) based on the calibration curves. The determination conditions are as follows.

[0150] <Measurement Conditions>

[0151] Device: HLC-8320GPC (Model) (Manufactured by Tosoh Corporation)

[0152] GPC columns: GF-710HQ, GF-510HQ, GF-310HQ (manufactured by Showa Denko Co., Ltd.)

[0153] Column temperature: 40℃

[0154] Solvent: 0.12% by mass lithium bromide-1-hydrate-dimethylformamide

[0155] Flow rate: 1.0 mL / min

[0156] Injection volume: 10 μL

[0157] Measurement time: 60 minutes

[0158] Standard sample: Polystyrene (manufactured by Showa Denko Co., Ltd.)

[0159] Detector: RI

[0160] [1] Polymer manufacturing

[0161] [Example 1-1]

[0162] <Step 1>

[0163] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 200 mL reaction flask by adding 15.0 g (0.082 mol) of barbital (manufactured by Yatsudai Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.) as 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. The solution was then heated under reflux at 130 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0164] The GPC results showed that the crude polymer had a Mw of 10300 and an Mw / Mn ratio of 5.8.

[0165] [Chemistry 15]

[0166]

[0167] <Step 2>

[0168] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of isopropanol adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was then redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 8.1 g of the target purified polymer.

[0169] The results of GPC analysis showed that the refined polymer had a Mw of 15600 and an Mw / Mn ratio of 1.9.

[0170] [Examples 1-2]

[0171] <Step 1>

[0172] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 200 mL reaction flask by adding 15.0 g (0.082 mol) of barbital (manufactured by Yatsudai Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.) as 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. The solution was then heated under reflux at 70 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0173] The GPC results showed that the crude polymer had a Mw of 12800 and an Mw / Mn ratio of 5.9.

[0174] <Step 2>

[0175] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of isopropanol adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was then redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 8.5 g of the target purified polymer.

[0176] The results of GPC analysis showed that the refined polymer had a Mw of 27,000 and an Mw / Mn ratio of 2.1.

[0177] [Examples 1-3]

[0178] <Step 1>

[0179] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 200 mL reaction flask by adding 18.1 g (0.098 mol) of barbital (manufactured by Yatsudai Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.) as 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. The solution was then heated under reflux at 130 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0180] The GPC results showed that the crude polymer had a Mw of 4700 and an Mw / Mn ratio of 3.8.

[0181] <Step 2>

[0182] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of isopropanol adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was then redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 7.9 g of the target purified polymer.

[0183] The results of GPC analysis showed that the refined polymer had a Mw of 7600 and an Mw / Mn ratio of 1.5.

[0184] [Examples 1-4]

[0185] <Step 1>

[0186] Under a nitrogen atmosphere, a raw material solution with a solid content of 40% by mass was prepared in a 200 mL reaction flask by adding 18.1 g (0.098 mol) of barbital (manufactured by Yatsudai Pharmaceutical Co., Ltd.) as component (a), 23.0 g (0.082 mol) of monoallyl diglycidyl isocyanuric acid (manufactured by Shikoku Chemical Industry Co., Ltd.) as 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. The solution was then heated under reflux at 130 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0187] The GPC results showed that the crude polymer had a Mw of 6400 and an Mw / Mn ratio of 3.6.

[0188] <Step 2>

[0189] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of isopropanol adjusted to 25°C over 30 minutes to allow redeposition, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, and the mixture was stirred for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was dried at 60°C using a vacuum dryer to obtain 16.9 g of the target purified polymer.

[0190] The results of GPC analysis showed that the Mw of the refined polymer was 10300 and the Mw / Mn ratio was 1.8.

[0191] [Examples 1-5]

[0192] <Step 1>

[0193] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 300 mL reaction flask by adding 14.9 g (0.071 mol) of 3,3'-dithiodipropionic acid (manufactured by Sakai Chemical Industry Co., Ltd., trade name: DTDPA) as component (a), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemical Industry Co., Ltd., product name: MA-DGIC) as component (b), 1.318 g (0.0071 mol) of ethyltriphenylphosphonium bromide (manufactured by Hokuko Chemical Industry Co., Ltd.), and 122.57 g of propylene glycol monomethyl ether. The solution was then heated under reflux at 105 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0194] The results of GPC analysis showed that the crude polymer had a Mw of 6700 and a polydispersity index (Mw / Mn) of 5.4.

[0195] [Chemistry 16]

[0196]

[0197] <Step 2>

[0198] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of cyclopentyl methyl ether adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The resulting precipitate was redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 5.1 g of the target purified polymer.

[0199] The results of GPC analysis showed that the refined polymer had a Mw of 10,000 and an Mw / Mn ratio of 3.8.

[0200] [Examples 1-6]

[0201] <Step 1>

[0202] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 300 mL reaction flask by adding 16.5 g (0.071 mol) of phenobarbital (manufactured by Yatsudai Pharmaceutical Co., Ltd.) as component (a), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemical Industry Co., Ltd., product name MA-DGIC) as 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. The solution was then heated under reflux at 105 °C for 24 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0203] The GPC results showed that the crude polymer had a Mw of 33400 and an Mw / Mn ratio of 16.3.

[0204] [Chemistry 17]

[0205]

[0206] <Step 2>

[0207] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of isopropanol adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was then redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of isopropanol over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 6.2 g of the target purified polymer.

[0208] The results of GPC analysis showed that the Mw of the refined polymer was 46200 and the Mw / Mn ratio was 10.5.

[0209] [Examples 1-7]

[0210] <Step 1>

[0211] Under a nitrogen atmosphere, a raw material solution with a solid content of 20% by mass was prepared in a 300 mL reaction flask by adding 8.24 g (0.071 mol) of fumaric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) as component (a), 20.0 g (0.071 mol) of monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemical Industry Co., Ltd., product name MA-DGIC) as 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. The solution was then heated under reflux at 120 °C for 8 hours to obtain a crude polymer solution. An equal amount of cation exchange resin (product name: DOWEX 550A, Muromachi Technos Co., Ltd.) and anion exchange resin (product name: Amberlyst 15JWET, ORGANO Co., Ltd.) were added to the crude polymer solution, respectively. Unreacted monomer components and catalysts used in the reaction were removed by ion exchange treatment at room temperature for 4 hours. The solution was then supplied to GPC determination and the second step.

[0212] The GPC results showed that the crude polymer had a Mw of 4600 and an Mw / Mn ratio of 3.1.

[0213] [Chemistry 18]

[0214]

[0215] <Step 2>

[0216] 50 g of the crude polymer solution obtained in step 1 was added to 500 g (10 times the mass of the reaction solution) of cyclopentyl methyl ether adjusted to 25°C over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The precipitate was then redissolved in 50 g of propylene glycol monomethyl ether, and the resulting polymer solution was added to 500 g (10 times the mass of the reaction solution) of cyclopentyl methyl ether over 30 minutes to allow redeposition, followed by stirring for another 30 minutes. The resulting precipitate was filtered under reduced pressure using a Kiriyama funnel (40φ) and filter paper (5A). The solution was dried at 60°C using a vacuum dryer to obtain 4.9 g of the target purified polymer.

[0217] The results of GPC analysis showed that the refined polymer had a Mw of 5100 and an Mw / Mn ratio of 2.9.

[0218] <Reduction rate of low molecular weight components>

[0219] In Examples 1-1 to 1-7, the effectiveness of the second step was examined by comparing the content of low molecular weight components with a Mw of less than 1000 in the crude polymer and the refined polymer.

[0220] The content and reduction rate of low molecular weight components are calculated through the following steps.

[0221] (1) Content of low molecular weight components

[0222] In a GPC graph where the horizontal axis represents elution time and the vertical axis represents the detection intensity, the content of low molecular weight components is calculated by integrating the integral values ​​of the entire region, removing the regions where the Mw of standard polystyrene (PS) is below 1000.

[0223] (2) Reduction rate of low molecular weight components

[0224] The content of the low molecular weight component obtained in (1) above is calculated according to the following formula.

[0225] [1 - (low molecular weight content of refined polymer ÷ low molecular weight content of crude polymer)] × 100 (mass%)

[0226] The results are shown in Table 1.

[0227] [Table 1]

[0228]

[0229] [2] Preparation of compositions for forming a resist underlayer film

[0230] <Example 2-1>

[0231] To 0.97 g of the purified polymer obtained in Examples 1-1, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0232] <Example 2-2>

[0233] To 0.97 g of the purified polymer obtained in Examples 1-1, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the lower layer film of the photoresist.

[0234] <Example 2-3>

[0235] To 0.97 g of the purified polymer obtained in Examples 1-2, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0236] <Example 2-4>

[0237] To 0.97 g of the purified polymer obtained in Examples 1-2, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the lower layer film of the photoresist.

[0238] <Examples 2-5>

[0239] To 0.97 g of the purified polymer obtained in Examples 1-3, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0240] <Example 2-6>

[0241] To 0.97 g of the purified polymer obtained in Examples 1-3, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0242] <Example 2-7>

[0243] To 0.97 g of the purified polymer obtained in Examples 1-4, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0244] <Example 2-8>

[0245] To 0.97 g of the purified polymer obtained in Examples 1-4, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0246] <Example 2-9>

[0247] To 0.97 g of the purified polymer obtained in Examples 1-5, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0248] <Example 2-10>

[0249] To 0.97 g of the purified polymer obtained in Examples 1-5, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0250] <Example 2-11>

[0251] To 0.97 g of the purified polymer obtained in Examples 1-6, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the lower layer film of the photoresist.

[0252] <Example 2-12>

[0253] To 0.97 g of the purified polymer obtained in Examples 1-6, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0254] <Example 2-13>

[0255] To 0.97 g of the purified polymer obtained in Examples 1-7, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0256] <Example 2-14>

[0257] To 0.97 g of the purified polymer obtained in Examples 1-7, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the lower layer film of the photoresist.

[0258] <Comparative Example 1-1>

[0259] To the crude polymer solution obtained in step 1 of Example 1-1 (4.86 g), 0.24 g of tetramethoxymethyl urea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0260] <Comparative Examples 1-2>

[0261] To the crude polymer solution obtained in step 1 of Example 1-1 (4.86 g), 0.24 g of tetramethoxymethyl urea (Cytec Industries, Ltd., Japan; 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 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 the lower layer film of the photoresist.

[0262] <Comparative Examples 1-3>

[0263] To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-2, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0264] <Comparative Examples 1-4>

[0265] To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-2, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0266] <Comparative Examples 1-5>

[0267] To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-3, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0268] <Comparative Examples 1-6>

[0269] To 4.86 g of the crude polymer solution obtained in the first step of Examples 1-3, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0270] <Comparative Examples 1-7>

[0271] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-4, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0272] <Comparative Examples 1-8>

[0273] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-4, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0274] <Comparative Examples 1-9>

[0275] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-5, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0276] <Comparative Examples 1-10>

[0277] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-5, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0278] <Comparative Examples 1-11>

[0279] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-6, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0280] <Comparative Examples 1-12>

[0281] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-6, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0282] <Comparative Examples 1-13>

[0283] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-7, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; trade name: POWDERLINK [registered trademark] 1174), 0.024 g of p-phenol sulfonic 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 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 the resist underlayer film.

[0284] <Comparative Examples 1-14>

[0285] To 4.86 g of the crude polymer solution obtained in step 1 of Examples 1-7, 0.24 g of tetramethoxymethyl glycourea (Cytec Industries, Ltd., Japan; 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 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 the resist underlayer film.

[0286] A list of the polymers and acid catalysts used in Examples 2-1 to 2-14 and Comparative Examples 1-1 to 1-14 is shown in Tables 2 and 3 below.

[0287] It should be noted that the abbreviations recorded in Table 1 are as follows.

[0288] PSA: p-phenolsulfonic acid

[0289] 5-SSA: 5-Sulfosalicylic acid

[0290] [Table 2]

[0291]

[0292] [Table 3]

[0293]

[0294] <Determination of Sublimation Content>

[0295] The compositions for forming the resist underlayer film prepared in Examples 2-1 to 2-14 and Comparative Examples 1-1 to 1-14 were spin-coated onto a 4-inch diameter silicon wafer substrate at 1500 rpm for 60 seconds. The wafer coated with the composition for forming the resist underlayer film was placed in a sublimation amount measuring device with an integrated heating plate (refer to International Publication No. 2007 / 111147) and baked for 120 seconds to capture the sublimation into a QCM (Quartz Crystal Microbalance) sensor, i.e., a quartz crystal oscillator with electrodes formed thereon. The QCM sensor utilizes the property that the frequency of the quartz crystal oscillator changes (decreases) according to its mass when sublimation adheres to the surface (electrodes) of the quartz crystal oscillator, and can measure minute changes in mass.

[0296] The detailed measurement procedure is as follows: Heat the heating plate of the sublimation content measuring device to 205℃, and set the pump flow rate to 1 m³ / min. 3 / s, for the initial 60 seconds to stabilize the device. Immediately afterwards, the wafer coated with the photoresist underlayer is rapidly placed on the heated plate through the sliding port, and sublimation capture is performed from 60 seconds to 120 seconds (60 seconds). It should be noted that the initial thickness of the photoresist underlayer formed on the wafer is 35 nm.

[0297] It should be noted that the flow accessory (detection part) connecting the QCM sensor and the trapping funnel in the aforementioned sublimation content measuring device is used without a nozzle. Therefore, the airflow does not narrow from the flow path (diameter: 32mm) of the chamber unit, which is 30mm away from the sensor (quartz crystal oscillator). Furthermore, the QCM sensor uses a material primarily composed of silicon and aluminum (AlSi) as electrodes, and employs a quartz crystal oscillator with a diameter (sensor diameter) of 14mm, an electrode diameter of 5mm on the quartz crystal oscillator surface, and a resonant frequency of 9MHz.

[0298] The obtained frequency change was converted to grams from the intrinsic value of the quartz crystal oscillator used in the measurement, thus determining the amount of sublimation on a wafer coated with a resist underlayer. The results are shown in Table 4.

[0299] In Table 4, X represents a film formed using a composition containing the crude polymer synthesized in step 1, and Y represents a film formed using a composition containing the refined polymer refined in step 2. Table 4 also confirms the effect of the presence or absence of a reprecipitation refining step on the sublimate.

[0300] [Table 4]

[0301] Y X Sublimation amount of Y / Sublimation amount of X Example 2-1 Comparative Example 1-1 0.55 Example 2-2 Comparative Examples 1-2 0.43 Example 2-3 Comparative Examples 1-3 0.60 Examples 2-4 Comparative Examples 1-4 0.61 Examples 2-5 Comparative Examples 1-5 0.25 Examples 2-6 Comparative Examples 1-6 0.23 Examples 2-7 Comparative Examples 1-7 0.51 Examples 2-8 Comparative Examples 1-8 0.53 Examples 2-9 Comparative Examples 1-9 0.46 Example 2-10 Comparative Examples 1-10 0.44 Example 2-11 Comparative Examples 1-11 0.87 Example 2-12 Comparative Examples 1-12 0.80 Example 2-13 Comparative Examples 1-13 0.32 Example 2-14 Comparative Examples 1-14 0.33

[0302] Based on the above description, the following results can be obtained: the resist underlayer film obtained from the composition for forming the resist underlayer film containing a refined polymer with a reduced content of low molecular weight components (Examples 2-1 to 2-14) is more effective at suppressing the formation of sublimation compared to the resist underlayer film obtained from the composition for forming the resist underlayer film containing a crude polymer (Comparative Examples 1-1 to 1-14).

Claims

1. A composition for forming a resist underlayer film, comprising a polymer having repeating units represented by formula (1-1) or (1-3) below and an organic solvent, wherein the polymer contains a low molecular weight component with a weight average molecular weight of 1000 or less in an amount of 10% by mass or less. The polymer has a weight-average molecular weight (Mw) of 2000–50000 and a polydispersity index (Mw / Mn) of less than 10.

5. 。 2. The composition for forming a resist underlayer film according to claim 1, further comprising a crosslinking agent.

3. The composition for forming a resist underlayer film according to claim 1 or 2, further comprising an acid catalyst.

4. A photoresist underlayer film, which is obtained from the composition for forming a photoresist underlayer film according to any one of claims 1 to 3.

5. A polymer having repeating units represented by formula (1-1) or formula (1-3) below, wherein the content of a low molecular weight component with a weight average molecular weight of 1000 or less is 10% by mass or less, the weight average molecular weight Mw of the polymer is 2000 to 50000, and the polydispersity index Mw / Mn of the polymer is 10.5 or less. 。

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