JP5326513B2 - Composition for forming an underlayer film for lithography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for forming a novel photoresist underlayer film excellent in optical characteristics and etching resistance, an underlayer film formed from the composition, having a high n value, a low k value, transparency and high etching resistance, and containing a very small amount of a sublimable component, and a pattern forming method using the underlayer film. <P>SOLUTION: The underlayer film forming composition for lithography comprises a polyimide having a repeating unit represented by general formula (1) and an organic solvent, wherein R represents a tetravalent aromatic group or aliphatic group derived from a hydrocarbon having a cyclic structure, an acyclic structure or a cyclic structure and an acyclic structure, and &Phi; represents a 2-39C constitutional unit that is an aliphatic constitutional unit, an alicyclic constitutional unit, an aromatic constitutional unit, an organosiloxane constitutional unit or a constitutional unit comprising a combination of these or repetition. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a composition for forming a lower layer film for lithography effective in a multilayer resist process used for microfabrication in a manufacturing process of a semiconductor element or the like, and a method for forming a photoresist pattern using the composition for forming a lower layer film for lithography.

  Conventionally, in the manufacture of semiconductor devices, fine processing by lithography using a photoresist composition has been performed. In recent years, along with higher integration and higher speed of LSIs, further miniaturization by pattern rules is required. In lithography using light exposure, which is currently used as a general-purpose technology, it is derived from the wavelength of the light source. It is approaching the limit of essential resolution.

  As a light source for lithography used for forming a resist pattern, the wavelength is shortened from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). However, various problems have arisen with miniaturization.

  One of the big issues is the aspect ratio. The ArF resist has a relatively low etching resistance, and it is necessary to increase the aspect ratio. However, the aspect ratio cannot be increased due to the collapse of the resist pattern. Therefore, as a means for forming a pattern with a high aspect ratio, a base material forming material is applied on a substrate, and this is heated to form a lower layer film, on which an intermediate layer made of a silica-based inorganic film is formed. After the film is provided, a photoresist film is further provided thereon, a resist pattern is formed by a normal photolithography technique, the pattern is transferred by etching the intermediate film using the resist pattern as a mask, and then patterned. A three-layer resist method has been proposed in which a lower layer film is subjected to oxygen plasma etching using the intermediate film as a mask to form a pattern on a substrate.

  In addition, a two-layer resist method that is superior in that it has fewer steps than the three-layer resist method has been proposed. In the two-layer resist method, a lower layer film is provided on a substrate in the same manner as the three-layer resist method, and then a photoresist film containing a silicon-containing polymer is provided on the upper layer, and a resist pattern is formed by ordinary photolithography technology. Then, etching with oxygen plasma is performed using the resist pattern as a mask, and the resist pattern is transferred to the lower layer film. Then, etching with a fluorocarbon gas or the like is performed using the resist pattern as a mask to form a pattern on the substrate (Non-patent Document 1).

  Here, as a lower layer film forming material for 193 nm, a copolymer of polyhydroxystyrene and an acrylate ester is generally studied. Polyhydroxystyrene has a very strong absorption at 193 nm, and the extinction coefficient (k) alone is a high value of around 0.6. Therefore, the k value can be adjusted to around 0.25 by copolymerizing with an acrylate ester having a k value of almost zero.

  However, with respect to polyhydroxystyrene, the etching resistance of acrylate esters in substrate etching is weak, and in order to lower the k value, it is necessary to copolymerize acrylate esters at a high rate, resulting in resistance to substrate etching. Had a deteriorating result. Since the resistance to etching appears not only in the etching rate but also in the occurrence of surface roughness after etching, the increase in surface roughness after etching becomes a serious problem due to copolymerization of acrylic acid esters.

  One of those having higher transparency at 193 nm and higher etching resistance than a benzene ring is a naphthalene ring, and a lower layer film having a naphthalene ring and an anthracene ring has been proposed (Patent Document 1). However, the k value of naphthol co-condensed novolak resin and polyvinyl naphthalene resin is between 0.3 and 0.4, and the target transparency of 0.1 to 0.3 has not been achieved. I have to raise it. Also in the acenaphthylene polymer (Patent Documents 2 and 3), the refractive index (n) at 193 nm is lower than the wavelength of 248 nm, the k value is high, and both do not reach the target value. Further, a lower layer film obtained by adding an acrylic resin to a naphthol co-condensed novolak resin (Patent Document 4), a polymer obtained by copolymerizing an indene and a compound having a hydroxy group or an epoxy group and having a double bond An underlayer film made of a compound (Patent Document 5) and an underlayer film made of a polymer compound obtained by copolymerizing fluorene bisphenol with a novolak resin (Patent Document 6) are disclosed, but the required level (k value: 0) .1 to 0.3) has not been reached.

  Further, in the lower layer film material, another problem is a sublimable component. The sublimate forms a crystal on the surface of the upper plate during baking, and the crystal falls on the wafer, which causes a defect. For these reasons, a material with less sublimation is required. Conventional materials use polymers such as novolac resins because of the requirement for etching resistance, but because they contain sublimable monomers, unreacted dimers and oligomer components, eliminating sublimation components increases the number of steps. The manufacturing cost is greatly affected.

  Thus, there is a need for a lower layer film material having a high n value, a low k value, transparency, high etching resistance, and extremely low sublimation components.

JP 2002-14474 A JP 2001-40293 A JP 2002-214777 A JP 2005-156816 A JP 2006-53543 A JP 2007-17867 A Proceedings of SPIE Vol.4345 (2001) 50

  The problem to be solved by the present invention is a composition for forming a novel photoresist underlayer film having excellent optical properties and etching resistance as an underlayer film for lithography, and a high n value and k value formed therefrom. The present invention provides a lower layer film that is low and transparent, has high etching resistance, and has very little sublimation component, and a pattern forming method using the same.

As a result of intensive studies to achieve the above object, the present inventors have found that a composition containing a polyimide having a specific structure and an organic solvent is excellent in optical characteristics and etching resistance, and is a promising material as an underlayer film for lithography. Has been found to provide the present invention. That is, the present invention is as follows.
1. A composition for forming a lower layer film for lithography, comprising a polyimide having a repeating unit represented by the general formula (1) and an organic solvent.
(In the formula (1), R is a cyclic structure, an acyclic structure, or a tetravalent aromatic group or an aliphatic group derived from a hydrocarbon having a cyclic structure and an acyclic structure. 39, a structural unit consisting of an aliphatic structural unit, an alicyclic structural unit, an aromatic structural unit, an organosiloxane structural unit, or a combination or repetition thereof, and the main chain of Φ has —O— , —SO ₂ —, —CO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —C ₂ H ₄ O—, and —S— intervene. You may do it.)
2. 2. The underlayer film forming composition for lithography according to claim 1, wherein R in the general formula (1) is a tetravalent group derived from cyclohexane.
3. The underlayer film forming composition for lithography according to claim 1 or 2, wherein Φ in the general formula (1) is a divalent group having a fluorene bisphenyl structure.
4). The underlayer film forming composition for lithography according to any one of claims 1 to 3, comprising a modified dimethylnaphthalene formaldehyde resin having a structural unit represented by the following general formula (2) in the molecule.
(In formula (2), each R independently represents a functional group selected from the group consisting of a hydrogen atom, a methoxymethyl group, a hydroxymethyl group, and a methylene group, X is — (O ₂ CH ₂ ) t—, 1 ≦ n ≦ 4, 0 ≦ t ≦ 2, Y is a saturated aliphatic hydrocarbon having 1 to 3 carbon atoms, and Y may be bonded to form a ring structure.
5. The underlayer film forming composition for lithography according to any one of Items 1 to 4, which contains an acid generator.
6). The underlayer film forming composition for lithography according to any one of Items 1 to 5, which contains a crosslinking agent.
7. An underlayer film for lithography formed from the underlayer film forming composition for lithography according to any one of Items 1 to 6.
8). After forming a lower layer film on the substrate using the lower layer film forming composition for lithography according to any one of Items 1 to 6, and forming at least one photoresist layer on the lower layer film The desired region of the photoresist layer is irradiated with radiation, and after alkali development to form a resist pattern, the lower layer film is etched with plasma containing at least oxygen gas using the resist pattern as a mask, and the lower layer film is resisted A method for forming a multilayer resist pattern, comprising transferring a pattern.

  By using the composition for forming a lower layer film for lithography of the present invention, a lower layer film having low reflectance of short wavelength light such as excimer laser light such as KrF and ArF and excellent etching resistance against oxygen plasma etching and the like is formed. An excellent resist pattern can be obtained by using the lower layer film.

  The polyimide used in the underlayer film forming composition for lithography of the present invention has a repeating unit represented by the following general formula (1).

However, in Formula (1), R is a tetravalent aromatic group or aliphatic group derived from a cyclic structure, an acyclic structure, or a hydrocarbon having a cyclic structure and an acyclic structure. Φ is a structural unit having 2 to 39 carbon atoms, and is a structural unit composed of an aliphatic structural unit, an alicyclic structural unit, an aromatic structural unit, an organosiloxane structural unit, or a combination or repetition thereof. The chain is at least selected from the group consisting of —O—, —SO ₂ —, —CO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —C ₂ H ₄ O—, and —S—. One partial structure may be interposed.

  Preferable R includes a tetravalent group derived from cyclohexane, cyclopentane, cyclobutane, bicyclo [2.2.2] oct-7-ene, and stereoisomers thereof. More specifically, a tetravalent group represented by the following structural formula can be given.

Of these, tetravalent groups derived from cyclohexane and stereoisomers thereof are more preferred.

  Preferable Φ includes polyalkylene, polyoxyalkylene, xylylene, and aliphatic structural units such as alkyl-substituted and halogen-substituted products thereof; cyclohexane, dicyclohexylmethane, dimethylcyclohexane, isophorone, norbornane, and alkyl-substituted products thereof. An alicyclic structural unit derived from a halogen-substituted product; and an aromatic structural unit derived from benzene, naphthalene, biphenyl, diphenylmethane, diphenyl ether, diphenylsulfone, benzophenone, and their alkyl-substituted products, halogen-substituted products, etc. And organosiloxane structural units. More specifically, structural units represented by the following structural formulas can be given.

  The content of the repeating unit represented by the general formula (1) is preferably 10 to 100 mol%, more preferably 50 to 100 mol% of all repeating units. The number of repeating units represented by the general formula (1) in one molecule of polyimide is preferably 10 to 2000, and more preferably 20 to 200.

  The polyimide used in the present invention can be obtained by reacting a tetracarboxylic acid component with a diamine component (diamine and derivatives thereof). Examples of the tetracarboxylic acid component include cyclohexanetetracarboxylic acid, cyclohexanetetracarboxylic acid esters, cyclohexanetetracarboxylic dianhydride, cyclobutanetetracarboxylic acid, cyclobutanetetracarboxylic acid esters, cyclobutanetetracarboxylic dianhydride, cyclopentanetetra Carboxylic acid, cyclopentanetetracarboxylic acid esters, cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-enetetracarboxylic acid, bicyclo [2.2.2] oct-7-ene Although tetracarboxylic dianhydride is mentioned, Cyclohexane tetracarboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, and cyclopentane tetracarboxylic dianhydride are preferable. More preferred is cyclohexanetetracarboxylic dianhydride. The tetracarboxylic acid component includes positional isomers.

  Specific examples of the tetracarboxylic acid component include, for example, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid methyl ester, 1,2,3, 4-butanetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic acid methyl ester, 1,2,3,4-cyclobutanetetracarboxylic acid 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid methyl ester, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2, 4,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic acid methyl ester, 3-carboxymethyl-1,2, -Cyclopentanetricarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3 5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid methyl ester, dicyclohexyltetracarboxylic acid, dicyclohexyltetracarboxylic dianhydride Products, dicyclohexyltetracarboxylic acid methyl ester, and the like.

  Of the tetracarboxylic acid components, a polyimide having a cyclohexanetetracarboxylic acid skeleton is preferable because it has a sufficiently high solubility in a solvent.

  As long as the tetracarboxylic acid component does not impair the solvent solubility of the polyimide, other tetracarboxylic acids or derivatives thereof such as pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3, 3 ′, 4′-biphenyltetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3-dicarboxyphenyl) propane, 2,2-bis (3 , 4-Dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3 Hexafluoropropane, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bis (2,3-dicarboxyphenyl) ether, 3,3 ′ 4,4′-benzophenone tetracarboxylic acid, 2,2 ′, 3,3′-benzophenone tetracarboxylic acid, 4,4- (p-phenylenedioxy) diphthalic acid, 4,4- (m-phenylenedioxy) Diphthalic acid, ethylenetetracarboxylic acid, 1,1-bis (2,3-dicarboxyphenyl) ethane, bis (2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, and their It may contain at least one compound selected from these derivatives.

  Examples of the diamine component include diamines, diisocyanates, and diaminodisilanes, with diamines being preferred. The diamine content in the diamine-based component is preferably 50 mol% or more (including 100 mol%).

  The diamine may be an aliphatic diamine, an aromatic diamine, or a mixture thereof. In the present invention, “aromatic diamine” means a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group, an alicyclic group, and other substituents are included in a part of the structure. May be. The “aliphatic diamine” represents a diamine in which an amino group is directly bonded to an aliphatic group or an alicyclic group, and an aromatic group and other substituents may be included in a part of the structure.

  In general, when an aliphatic diamine is used as a constituent component, the polyamic acid as an intermediate product and the aliphatic diamine form a strong complex, and thus it is difficult to obtain a high molecular weight polyimide. Therefore, it is necessary to devise such as using a solvent having a relatively high solubility of the complex, such as cresol. However, when an aliphatic tetracarboxylic acid or a derivative thereof and an aliphatic diamine are used as constituent components, a complex having a relatively weak bond between the polyamic acid and the aliphatic diamine is formed, so that the polyimide can be easily increased in molecular weight.

Examples of the aliphatic diamine include 4,4′-diaminodicyclohexylmethane, ethylenediamine, hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, and 1,3- Examples thereof include bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, m-xylylenediamine, p-xylylenediamine, isophorone diamine, norbornane diamine, and siloxane diamines.
Examples of the aromatic diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, m-phenylenediamine, p-phenylenediamine, diaminobenzophenone, and 2,6. -Diaminonaphthalene, 1,5-diaminonaphthalene, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (p-phenylenediisopropylidene) dianiline, 9,9'-bis (4- Aminophenyl) fluorene and the like. In particular, 9,9′-bis (4-aminophenyl) fluorene is preferable because of high etching resistance and small sublimation components.

  The glass transition temperature of the polyimide used in the present invention varies depending on the diamine selected, but is generally 350 ° C. or lower. Although depending on the amount of residual solvent, adhesiveness is exhibited at a temperature higher than the glass transition temperature. Therefore, if the glass transition temperature is too high, the thermocompression bonding temperature becomes too high, and if the glass transition temperature is too low, the resin composition layer Or the heat resistance of the polyimide layer itself described later is insufficient, which is not preferable. The range of a preferable glass transition temperature is 200 to 350 ° C., and particularly preferably 250 to 320 ° C.

The underlayer film forming composition for lithography of the present invention preferably contains a modified dimethylnaphthalene formaldehyde resin having a structural unit represented by the following general formula (2) in the molecule. Etching resistance can be improved by including the resin.
However, in formula (2), each R independently represents a functional group selected from the group consisting of a hydrogen atom, a methoxymethyl group, a hydroxymethyl group, and a methylene group, X is — (O ₂ CH ₂ ) t—, 1 ≦ n ≦ 4 and 0 ≦ t ≦ 2. Y is a saturated aliphatic hydrocarbon having 1 to 3 carbon atoms, and Y may be bonded to form a ring structure.

  The amount of the resin added is preferably 10 to 50 parts, more preferably 10 to 40 parts with respect to 100 parts of polyimide (parts by mass, the same applies hereinafter). When the amount is less than 10 parts, the effect of improving etching resistance is small and the crosslinking reaction may be insufficient. When the amount exceeds 50 parts, the sublimation component may be large.

  The underlayer film forming composition for lithography of the present invention can contain a crosslinking agent and / or an acid generator in order to suppress intermixing. Specific examples of the crosslinking agent that can be used in the present invention include a melamine compound, a guanamine compound, a glycoluril compound, or a urea compound substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. Examples of the compound include a double bond such as an epoxy compound, a thioepoxy compound, an isocyanate compound, an azide compound, and an alkenyl ether group. These may be used as additives, but these crosslinkable groups may be introduced as pendant groups into the polymer side chain. A compound containing a hydroxy group is also used as a crosslinking agent.

  Examples of the epoxy compound among the various compounds include tris (2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, triethylolethane triglycidyl ether and the like. Specific examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, Examples thereof include compounds in which 1 to 6 methylol groups of hexamethylolmelamine are acyloxymethylated, or a mixture thereof. Examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or a mixture thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, and tetramethylolguanamine. A compound in which ˜4 methylol groups are acyloxymethylated or a mixture thereof may be mentioned. Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethylglycoluril, a compound in which 1 to 4 methylol groups of tetramethylolglycoluril are methoxymethylated, or a mixture thereof, and tetramethylolglycoluril methylol. Examples thereof include compounds in which 1 to 4 of the groups are acyloxymethylated or a mixture thereof. Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, a mixture thereof, tetramethoxyethyl urea, and the like.

  Examples of the compound containing an alkenyl ether group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, Examples include trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, trimethylolpropane trivinyl ether, and the like.

  The blending amount of the crosslinking agent in the present invention is preferably 5 to 50 parts, more preferably 10 to 40 parts, with respect to 100 parts of polyimide (parts by mass). If it is less than 5 parts, it may cause mixing with the resist. If it exceeds 50 parts, the antireflection effect may be reduced, or cracks may occur in the crosslinked film.

  In the present invention, an acid generator for further promoting the crosslinking reaction by heat can be added. There are acid generators that generate an acid by thermal decomposition and those that generate an acid by light irradiation, and any of them can be added.

As the acid generator used in the present invention,
1) Onium salt of the following general formula (P1a-1), (P1a-2), (P1a-3) or (P1b),
2) a diazomethane derivative of the following general formula (P2),
3) a glyoxime derivative of the following general formula (P3),
4) A bissulfone derivative of the following general formula (P4),
5) A sulfonic acid ester of an N-hydroxyimide compound of the following general formula (P5),
6) β-ketosulfonic acid derivative,
7) a disulfone derivative,
8) Nitrobenzyl sulfonate derivative,
9) Sulfonic acid ester derivatives and the like.

(In the formula (P1a), R ^101a , R ^101b and R ^101c are each a linear, branched or cyclic alkyl group, alkenyl group, oxoalkyl group or oxoalkenyl group having 1 to 12 carbon atoms, 6 to 6 carbon atoms, 20 aryl groups, aralkyl groups having 7 to 12 carbon atoms, or aryloxoalkyl groups, part or all of hydrogen atoms of these groups may be substituted with alkoxy groups, etc. In addition, R ^101b and R ^101c may form a ring, and in the case of forming a ring, R ^101b and R ^101c each represent an alkylene group having 1 to 6 carbon atoms, and K ⁻ represents a non-nucleophilic counter ion. R ^101d , R ^101e , R ^101f and R ^101g are shown by adding a hydrogen atom to R ^101a , R ^101b and R ^101c , R ^101d and R ^101e , R ^101d , R ^101e and R ^101f form a ring. and may, when they form a ring, R ^101d, R ^101e and ^101d, R ^101e and R ^101f represents a heteroaromatic ring having a nitrogen atom in. Or formula represents an alkylene group having 3 to 10 carbon atoms in the ring.)

R ^101a , R ^101b , R ^101c , R ^101d , R ^101e , R ^101f and R ^101g may be the same as or different from each other. Specifically, as an alkyl group, a methyl group, an ethyl group, a propyl group , Isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopropylmethyl group, 4-methylcyclohexyl Group, cyclohexylmethyl group, norbornyl group, adamantyl group and the like. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Examples of the oxoalkyl group include 2-oxocyclopentyl group, 2-oxocyclohexyl group, and the like. 2-oxopropyl group, 2-cyclopentyl-2-oxoethyl group, 2-cyclohexyl-2-oxoethyl group, 2- (4 -Methylcyclohexyl) -2-oxoethyl group and the like can be mentioned. Examples of the aryl group include a phenyl group, a naphthyl group, a p-methoxyphenyl group, an m-methoxyphenyl group, an o-methoxyphenyl group, an ethoxyphenyl group, a p-tert-butoxyphenyl group, and an m-tert-butoxyphenyl group. Alkylphenyl groups such as alkoxyphenyl groups, 2-methylphenyl groups, 3-methylphenyl groups, 4-methylphenyl groups, ethylphenyl groups, 4-tert-butylphenyl groups, 4-butylphenyl groups, dimethylphenyl groups, etc. Alkyl naphthyl groups such as methyl naphthyl group and ethyl naphthyl group, alkoxy naphthyl groups such as methoxy naphthyl group and ethoxy naphthyl group, dialkyl naphthyl groups such as dimethyl naphthyl group and diethyl naphthyl group, dimethoxy naphthyl group and diethoxy naphthyl group Dialkoxynaphthyl group And the like. Examples of the aralkyl group include a benzyl group, a phenylethyl group, and a phenethyl group. As the aryloxoalkyl group, 2-aryl-2-oxoethyl group such as 2-phenyl-2-oxoethyl group, 2- (1-naphthyl) -2-oxoethyl group, 2- (2-naphthyl) -2-oxoethyl group and the like Groups and the like. K ^- a non-nucleophilic counter chloride ions as the ion, halide ions such as bromide ion, triflate, 1,1,1-trifluoroethane sulfonate, fluoroalkyl sulfonate such as nonafluorobutanesulfonate, tosylate, benzenesulfonate And aryl sulfonates such as 4-fluorobenzene sulfonate and 1,2,3,4,5-pentafluorobenzene sulfonate, and alkyl sulfonates such as mesylate and butane sulfonate.

In addition, R ^101d is a heteroaromatic ring in which R ^101e , R ^101f , and R ^{101g each} have a nitrogen atom in the formula is an imidazole derivative (for example, imidazole, 4-methylimidazole, 4-methyl-2-phenyl). Imidazole etc.), pyrazole derivatives, furazane derivatives, pyrroline derivatives (eg pyrroline, 2-methyl-1-pyrroline etc.), pyrrolidine derivatives (eg pyrrolidine, N-methylpyrrolidine, pyrrolidinone, N-methylpyrrolidone etc.), imidazoline derivatives, imidazo Lysine derivatives, pyridine derivatives (eg pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4- (1-butylpentyl) pyridine, dimethylpyridine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridy , 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone, 4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine, 2- ( 1-ethylpropyl) pyridine, aminopyridine, dimethylaminopyridine, etc.), pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives, pyrazoline derivatives, pyrazolidine derivatives, piperidine derivatives, piperazine derivatives, morpholine derivatives, indole derivatives, isoindole derivatives, 1H-indazole Derivatives, indoline derivatives, quinoline derivatives (eg quinoline, 3-quinolinecarbonitrile, etc.), isoquinoline derivatives, cinnoline derivatives, quinazoline derivatives, quinoxaline derivatives, phthalas Derivatives, purine derivatives, pteridine derivatives, carbazole derivatives, phenanthridine derivatives, acridine derivatives, phenazine derivatives, 1,10-phenanthroline derivatives, adenine derivatives, adenosine derivatives, guanine derivatives, guanosine derivatives, uracil derivatives, uridine derivatives, etc. Is done.

  The general formula (P1a-1) and the general formula (P1a-2) have both effects of a photoacid generator and a thermal acid generator, but the general formula (P1a-3) acts as a thermal acid generator. .

(In the formula (P1b), R ^102a and R ^102b each represent a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. R ¹⁰³ is a linear, branched or cyclic group having 1 to 10 carbon atoms. R ^104a and R ^104b each represents a 2-oxoalkyl group having 3 to 7 carbon atoms, and K ⁻ represents a non-nucleophilic counter ion.

Specific examples of R ^102a and R ^102b include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. , Cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group and the like. R ¹⁰³ is methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, 1,4-cyclohexylene group, 1,2-cyclohexylene. Group, 1,3-cyclopentylene group, 1,4-cyclooctylene group, 1,4-cyclohexanedimethylene group and the like. ^{Examples of} R ^104a and R ^104b include a 2-oxopropyl group, a 2-oxocyclopentyl group, a 2-oxocyclohexyl group, and a 2-oxocycloheptyl group. K ^- is the formula (P1a-1), can be exemplified the same ones as described in (P1a-2) and (P1a-3).

(In the formula (P2), R ¹⁰⁵ and R ¹⁰⁶ are linear, branched or cyclic alkyl groups or halogenated alkyl groups having 1 to 12 carbon atoms, aryl groups or halogenated aryl groups having 6 to 20 carbon atoms, Or an aralkyl group having 7 to 12 carbon atoms.)

^Examples of the alkyl group represented by R ¹⁰⁵ and R ¹⁰⁶ include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, Examples include amyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, norbornyl group, adamantyl group and the like. Examples of the halogenated alkyl group include a trifluoromethyl group, a 1,1,1-trifluoroethyl group, a 1,1,1-trichloroethyl group, a nonafluorobutyl group, and the like. As the aryl group, an alkoxyphenyl group such as a phenyl group, a p-methoxyphenyl group, an m-methoxyphenyl group, an o-methoxyphenyl group, an ethoxyphenyl group, a p-tert-butoxyphenyl group, or an m-tert-butoxyphenyl group. And alkylphenyl groups such as 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, ethylphenyl group, 4-tert-butylphenyl group, 4-butylphenyl group, and dimethylphenyl group. Examples of the halogenated aryl group include a fluorophenyl group, a chlorophenyl group, and 1,2,3,4,5-pentafluorophenyl group. Examples of the aralkyl group include a benzyl group and a phenethyl group.

(In the formula (P3), R ¹⁰⁷ , R ¹⁰⁸ and R ¹⁰⁹ are each a linear, branched or cyclic alkyl group or halogenated alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms or a halogenated group. An aryl group, or an aralkyl group having 7 to 12 carbon atoms, R ¹⁰⁸ and R ¹⁰⁹ may be bonded to each other to form a cyclic structure, and when forming a cyclic structure, R ¹⁰⁸ and R ¹⁰⁹ are each a carbon number; 1 to 6 linear or branched alkylene groups are shown.)

Examples of the alkyl group, halogenated alkyl group, aryl group, halogenated aryl group, and aralkyl group of R ¹⁰⁷ , R ¹⁰⁸ , and R ¹⁰⁹ include the same groups as those described for R ¹⁰⁵ and R ¹⁰⁶ . ^Examples of the alkylene group for R ¹⁰⁸ and R ¹⁰⁹ include a methylene group, an ethylene group, a propylene group, a butylene group, and a hexylene group.

(In formula (P4), R ^101a and R ^101b are the same as above.)

(In the formula (P5), R ¹¹⁰ represents an arylene group having 6 to 10 carbon atoms, an alkylene group having 1 to 6 carbon atoms, or an alkenylene group having 2 to 6 carbon atoms, and part or all of the hydrogen atoms of these groups May be further substituted with a linear or branched alkyl group or alkoxy group having 1 to 4 carbon atoms, an nitro group, an acetyl group, or a phenyl group, and R ¹¹¹ is a straight chain having 1 to 8 carbon atoms. A branched or substituted alkyl group, an alkenyl group or an alkoxyalkyl group, a phenyl group, or a naphthyl group, wherein some or all of the hydrogen atoms of these groups are further an alkyl group or alkoxy group having 1 to 4 carbon atoms; A phenyl group which may be substituted by an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a nitro group or an acetyl group; a heteroaromatic group having 3 to 5 carbon atoms; or a substituent which may be substituted by a chlorine atom or a fluorine atom Good.)

Here, as the arylene group of R ¹¹⁰ , 1,2-phenylene group, 1,8-naphthylene group, etc., and as the alkylene group, methylene group, ethylene group, trimethylene group, tetramethylene group, phenylethylene group, norbornane Examples of the alkenylene group such as -2,3-diyl group include 1,2-vinylene group, 1-phenyl-1,2-vinylene group, 5-norbornene-2,3-diyl group and the like. The alkyl group for R ¹¹¹ is the same as R ^{101a to} R ^101c, and the alkenyl group is a vinyl group, 1-propenyl group, allyl group, 1-butenyl group, 3-butenyl group, isoprenyl group, 1- Pentenyl group, 3-pentenyl group, 4-pentenyl group, dimethylallyl group, 1-hexenyl group, 3-hexenyl group, 5-hexenyl group, 1-heptenyl group, 3-heptenyl group, 6-heptenyl group, 7-octenyl Groups such as alkoxyalkyl groups include methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, pentyloxymethyl, hexyloxymethyl, heptyloxymethyl, methoxyethyl, ethoxyethyl, Propoxyethyl, butoxyethyl, pentyloxyethyl, hexyloxyethyl, methoxypro Group, ethoxypropyl group, propoxypropyl group, butoxy propyl group, methoxybutyl group, ethoxybutyl group, propoxybutyl group, a methoxy pentyl group, an ethoxy pentyl group, a methoxy hexyl group, a methoxy heptyl group.

  In addition, examples of the optionally substituted alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. As the alkoxy group of ˜4, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group and the like are an alkyl group having 1 to 4 carbon atoms, an alkoxy group, and a nitro group. As the phenyl group which may be substituted with an acetyl group, a phenyl group, a tolyl group, a p-tert-butoxyphenyl group, a p-acetylphenyl group, a p-nitrophenyl group, etc. are heterocycles having 3 to 5 carbon atoms. Examples of the aromatic group include a pyridyl group and a furyl group.

  Specifically, for example, tetramethylammonium trifluoromethanesulfonate, tetramethylammonium nonafluorobutanesulfonate, triethylammonium nonafluorobutanesulfonate, pyridinium nonafluorobutanesulfonate, triethylammonium camphorsulfonate, pyridinium camphorsulfonate, nona Tetra n-butylammonium fluorobutanesulfonate, tetraphenylammonium nonafluorobutanesulfonate, tetramethylammonium p-toluenesulfonate, diphenyliodonium trifluoromethanesulfonate, phenyliodonium trifluoromethanesulfonate (p-tert-butoxyphenyl) phenyliodonium, p-Toluenesulfonic acid diphenyliodonium, p-toluenesulfonic acid ( -Tert-butoxyphenyl) phenyliodonium, triphenylsulfonium trifluoromethanesulfonate, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, bis (p-tert-butoxyphenyl) phenylsulfonium trifluoromethanesulfonate, trifluoromethane Tris (p-tert-butoxyphenyl) sulfonium sulfonate, triphenylsulfonium p-toluenesulfonate, p-toluenesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, bis (p-tert-butoxy) p-toluenesulfonate Phenyl) phenylsulfonium, p-toluenesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, nonafluorobuta Triphenylsulfonium sulfonate, triphenylsulfonium butanesulfonate, trimethylsulfonium trifluoromethanesulfonate, trimethylsulfonium p-toluenesulfonate, cyclohexylmethyl trifluoromethanesulfonate (2-oxocyclohexyl) sulfonium, cyclohexylmethyl p-toluenesulfonate ( 2-oxocyclohexyl) sulfonium, dimethylphenylsulfonium trifluoromethanesulfonate, dimethylphenylsulfonium p-toluenesulfonate, dicyclohexylphenylsulfonium trifluoromethanesulfonate, dicyclohexylphenylsulfonium p-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate, trifluoro Lomethanesulfone Cyclohexylmethyl (2-oxocyclohexyl) sulfonium acid, trifluoromethanesulfonic acid (2-norbornyl) methyl (2-oxocyclohexyl) sulfonium, ethylenebis [methyl (2-oxocyclopentyl) sulfonium trifluoromethanesulfonate], 1,2 ' -Onium salts such as naphthylcarbonylmethyltetrahydrothiophenium triflate.

  Bis (benzenesulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (xylenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (cyclopentylsulfonyl) diazomethane, bis (n-butylsulfonyl) diazomethane, bis (isobutylsulfonyl) ) Diazomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propylsulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (n-amylsulfonyl) diazomethane, bis (isoamylsulfonyl) ) Diazomethane, bis (sec-amylsulfonyl) diazomethane, bis (tert-amylsulfonyl) diazomethane, B hexylsulfonyl-1-(tert-butylsulfonyl) diazomethane, 1-cyclohexyl sulfonyl-1-(tert-amylsulfonyl) diazomethane, 1-tert-amylsulfonyl-1-(tert-butylsulfonyl) diazomethane derivatives such as diazomethane.

  Bis- (p-toluenesulfonyl) -α-dimethylglyoxime, bis- (p-toluenesulfonyl) -α-diphenylglyoxime, bis- (p-toluenesulfonyl) -α-dicyclohexylglyoxime, bis- (p- Toluenesulfonyl) -2,3-pentanedione glyoxime, bis- (p-toluenesulfonyl) -2-methyl-3,4-pentanedione glyoxime, bis- (n-butanesulfonyl) -α-dimethylglyoxime, Bis- (n-butanesulfonyl) -α-diphenylglyoxime, bis- (n-butanesulfonyl) -α-dicyclohexylglyoxime, bis- (n-butanesulfonyl) -2,3-pentanedione glyoxime, bis- (N-Butanesulfonyl) -2-methyl-3,4-pentanedioneglyoxy Bis- (methanesulfonyl) -α-dimethylglyoxime, bis- (trifluoromethanesulfonyl) -α-dimethylglyoxime, bis- (1,1,1-trifluoroethanesulfonyl) -α-dimethylglyoxime, bis -(Tert-butanesulfonyl) -α-dimethylglyoxime, bis- (perfluorooctanesulfonyl) -α-dimethylglyoxime, bis- (cyclohexanesulfonyl) -α-dimethylglyoxime, bis- (benzenesulfonyl) -α -Dimethylglyoxime, bis- (p-fluorobenzenesulfonyl) -α-dimethylglyoxime, bis- (p-tert-butylbenzenesulfonyl) -α-dimethylglyoxime, bis- (xylenesulfonyl) -α-dimethylglyoxime Oxime, bis- (camphorsul Glyoxime derivatives such as phonyl) -α-dimethylglyoxime.

  Bissulfone derivatives such as bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane, bisethylsulfonylmethane, bispropylsulfonylmethane, bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, and bisbenzenesulfonylmethane.

  Β-ketosulfone derivatives such as 2-cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane and 2-isopropylcarbonyl-2- (p-toluenesulfonyl) propane.

  Disulfone derivatives such as diphenyldisulfone derivatives and dicyclohexyldisulfone derivatives.

  Nitrobenzyl sulfonate derivatives such as 2,6-dinitrobenzyl p-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate.

  Sulfonic acid ester derivatives such as 1,2,3-tris (methanesulfonyloxy) benzene, 1,2,3-tris (trifluoromethanesulfonyloxy) benzene, 1,2,3-tris (p-toluenesulfonyloxy) benzene .

  N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimide trifluoromethanesulfonic acid ester, N-hydroxysuccinimide ethanesulfonic acid ester, N-hydroxysuccinimide 1-propanesulfonic acid ester, N-hydroxysuccinimide 2-propanesulfonic acid ester, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide 1-octanesulfonic acid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester, N-hydroxysuccinimide p-methoxybenzenesulfonic acid ester, N-hydroxysuccinimide 2 -Chloroethane sulfonic acid ester, N-hydroxysuccinimide benzene sulfonic acid ester, N- Droxysuccinimide-2,4,6-trimethylbenzenesulfonate, N-hydroxysuccinimide 1-naphthalenesulfonate, N-hydroxysuccinimide 2-naphthalenesulfonate, N-hydroxy-2-phenylsuccinimide methanesulfonate N-hydroxymaleimide methanesulfonic acid ester, N-hydroxymaleimide ethanesulfonic acid ester, N-hydroxy-2-phenylmaleimide methanesulfonic acid ester, N-hydroxyglutarimide methanesulfonic acid ester, N-hydroxyglutarimide benzenesulfonic acid Esters, N-hydroxyphthalimide methanesulfonate, N-hydroxyphthalimidebenzenesulfonate, N-hydroxyphthalate Imidotrifluoromethanesulfonic acid ester, N-hydroxyphthalimide p-toluenesulfonic acid ester, N-hydroxynaphthalimide methanesulfonic acid ester, N-hydroxynaphthalimide benzenesulfonic acid ester, N-hydroxy-5-norbornene-2,3- Dicarboximide methanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboximide trifluoromethanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboximide p-toluenesulfonate Sulfonic acid ester derivatives of N-hydroxyimide compounds such as triphenylsulfonium trifluoromethanesulfonate, trifluoromethanesulfonic acid (p-tert-buto Xylphenyl) diphenylsulfonium, trifluoromethanesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, p-toluenesulfonic acid triphenylsulfonium, p-toluenesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, p-toluenesulfonic acid Tris (p-tert-butoxyphenyl) sulfonium, trifluoromethanesulfonic acid trinaphthylsulfonium, trifluoromethanesulfonic acid cyclohexylmethyl (2-oxocyclohexyl) sulfonium, trifluoromethanesulfonic acid (2-norbornyl) methyl (2-oxocyclohexyl) sulfonium Onium salts such as 1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate, bis (benzenes) Phonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (n-butylsulfonyl) diazomethane, bis (isobutylsulfonyl) diazomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propyl) Sulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, diazomethane derivatives such as bis (tert-butylsulfonyl) diazomethane, bis- (p-toluenesulfonyl) -α-dimethylglyoxime, bis- (n-butanesulfonyl) -α- Glyoxime derivatives such as dimethylglyoxime, bissulfone derivatives such as bisnaphthylsulfonylmethane, N-hydroxysuccinimide methanesulfonate, N-hydroxysucci Imidotrifluoromethanesulfonic acid ester, N-hydroxysuccinimide 1-propanesulfonic acid ester, N-hydroxysuccinimide 2-propanesulfonic acid ester, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester , N-hydroxynaphthalimide methanesulfonic acid ester, N-hydroxynaphthalimide benzenesulfonic acid ester, and other sulfonic acid ester derivatives of N-hydroxyimide compounds are preferably used.

In addition, the said acid generator can be used individually by 1 type or in combination of 2 or more types.
The addition amount of the acid generator is preferably 0.1 to 50 parts, more preferably 0.5 to 40 parts with respect to 100 parts of polyimide (parts by mass, the same shall apply hereinafter). If the amount is less than 0.1 part, the amount of acid generated is small and the crosslinking reaction may be insufficient. If the amount exceeds 50 parts, a mixing phenomenon may occur due to the acid moving to the upper resist.

Furthermore, the basic compound for improving storage stability can be mix | blended with the lower layer film formation composition for lithography of this invention. As a basic compound, it plays the role of the quencher with respect to an acid in order to prevent the acid which generate | occur | produced in trace amount from the acid generator to advance a crosslinking reaction.
Examples of such basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, and sulfonyl groups. A nitrogen-containing compound having a hydroxyl group, a nitrogen-containing compound having a hydroxyl group, a nitrogen-containing compound having a hydroxyphenyl group, an alcoholic nitrogen-containing compound, an amide derivative, an imide derivative, and the like.

  Specifically, primary aliphatic amines include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, tert- Amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, tetraethylenepentamine, etc. are exemplified as secondary aliphatic amines. Dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, disi Lopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N, N-dimethylmethylenediamine, N, N-dimethylethylenediamine, N, N-dimethyltetraethylenepenta Examples of tertiary aliphatic amines include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, and tripentylamine. , Tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, Examples include cetylamine, N, N, N ′, N′-tetramethylmethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethyltetraethylenepentamine and the like. Is done.

  Examples of hybrid amines include dimethylethylamine, methylethylpropylamine, benzylamine, phenethylamine, and benzyldimethylamine. Specific examples of aromatic amines and heterocyclic amines include aniline derivatives (eg, aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N, N-dimethylaniline, 2-methylaniline, 3- Methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline, 3,5- Dinitroaniline, N, N-dimethyltoluidine, etc.), diphenyl (p-tolyl) amine, methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole derivatives (eg pyrrole, 2H-pyrrole, 1-methylpyrrole, 2,4-dim Lupyrrole, 2,5-dimethylpyrrole, N-methylpyrrole, etc.), oxazole derivatives (eg oxazole, isoxazole etc.), thiazole derivatives (eg thiazole, isothiazole etc.), imidazole derivatives (eg imidazole, 4-methylimidazole, 4 -Methyl-2-phenylimidazole, etc.), pyrazole derivatives, furazane derivatives, pyrroline derivatives (eg pyrroline, 2-methyl-1-pyrroline etc.), pyrrolidine derivatives (eg pyrrolidine, N-methylpyrrolidine, pyrrolidinone, N-methylpyrrolidone etc.) ), Imidazoline derivatives, imidazolidine derivatives, pyridine derivatives (eg pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4- (1-butylpentyl) pyridine, dimethyl) Lysine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone, 4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine, 2- (1-ethylpropyl) pyridine, aminopyridine, dimethylaminopyridine, etc.), pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives, pyrazoline derivatives, pyrazolidine derivatives, piperidine Derivatives, piperazine derivatives, morpholine derivatives, indole derivatives, isoindole derivatives, 1H-indazole derivatives, indoline derivatives, quinoline derivatives (eg quinoline, 3-quinoline carbo Nitriles), isoquinoline derivatives, cinnoline derivatives, quinazoline derivatives, quinoxaline derivatives, phthalazine derivatives, purine derivatives, pteridine derivatives, carbazole derivatives, phenanthridine derivatives, acridine derivatives, phenazine derivatives, 1,10-phenanthroline derivatives, adenine derivatives, adenosine Examples include derivatives, guanine derivatives, guanosine derivatives, uracil derivatives, uridine derivatives and the like.

  Furthermore, examples of the nitrogen-containing compound having a carboxy group include aminobenzoic acid, indolecarboxylic acid, amino acid derivatives (for example, nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine. , Phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, methoxyalanine) and the like, and nitrogen-containing compounds having a sulfonyl group include 3-pyridinesulfonic acid, p-toluenesulfonic acid pyridinium, and the like. Nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, and alcoholic nitrogen-containing compounds include 2-hydroxypyridine, aminocresol, 2,4-quinolinediol, and 3-indolemethanol. Drate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N, N-diethylethanolamine, triisopropanolamine, 2,2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol 4-amino-1-butanol, 4- (2-hydroxyethyl) morpholine, 2- (2-hydroxyethyl) pyridine, 1- (2-hydroxyethyl) piperazine, 1- [2- (2-hydroxyethoxy) Ethyl] piperazine, piperidineethanol, 1- (2-hydroxyethyl) pyrrolidine, 1- (2-hydroxyethyl) -2-pyrrolidinone, 3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propane Diol, 8-hydroxyuroli , 3-cuincridinol, 3-tropanol, 1-methyl-2-pyrrolidineethanol, 1-aziridineethanol, N- (2-hydroxyethyl) phthalimide, N- (2-hydroxyethyl) isonicotinamide, etc. Illustrated. Examples of amide derivatives include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide and the like. Examples of the imide derivative include phthalimide, succinimide, maleimide and the like.

  The compounding amount of the basic compound is preferably 0.001 to 2 parts, particularly 0.01 to 1 part with respect to 100 parts of polyimide (parts by mass). When the blending amount is less than 0.001 part, there is no blending effect, and when it exceeds 2 parts, all of the acid generated by heat may be trapped and crosslinking may not occur.

  In addition, another resin and / or compound may be added to the composition for forming a lower layer film for lithography of the present invention for the purpose of imparting thermosetting properties or controlling the absorbance. Highly transparent naphthol resin, naphthalene diol resin, xylene resin, naphthol modified resin, phenol modified resin of naphthalene resin, polyhydroxystyrene, dicyclopentadiene resin, (meth) acrylate, dimethacrylate, trimethacrylate, tetramethacrylate, vinyl Resin containing no naphthalene ring such as naphthalene and polyacenaphthylene, biphenyl ring such as phenanthrenequinone and fluorene, heterocycle having a heteroatom such as thiophene and indene and aromatic ring; rosin resin, cyclodextrin, Resins or compounds containing an alicyclic structure such as adamantane (poly) ol, tricyclodecane (poly) ol, and derivatives thereof can also be added.

  In addition, in the composition for forming a lower layer film for lithography of the present invention, metal particles such as titanium oxide or inorganic particles such as fullerene having an average particle diameter not exceeding 1 micron can be added. By adding metal particles or inorganic particles, the dry etching rate can be slowed and the selectivity with respect to the photoresist can be increased.

The organic solvent that can be used in the underlayer film forming composition for lithography according to the present invention is not particularly limited as long as the polymer, polyphenol compound, cyclic organic compound, acid generator, crosslinking agent, and other additives can be dissolved. There is no.
For example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cellosolve solvents such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate , Ester solvents such as methyl methoxypropionate, methyl hydroxyisobutyrate and γ-butyrolactone, alcohol solvents such as methanol, ethanol, isopropanol and 1-ethoxy-2-propanol, and aromatic hydrocarbons such as toluene, xylene and anisole And amide solvents such as dimethylacetamide.
Among the above organic solvents, cyclohexanone, γ-butyrolactone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, methyl hydroxyisobutyrate, anisole and dimethylacetamide are particularly preferable.

  The blending amount of the organic solvent is preferably 200 to 10,000 parts, particularly preferably 300 to 5,000 parts, with respect to 100 parts of polyimide (parts by mass, the same shall apply hereinafter).

In the method for forming an underlayer film of the present invention, first, an underlayer film is formed on a substrate using the underlayer film forming composition for lithography of the present invention. In this case, for example, after spin coating, it is desirable to volatilize the organic solvent and to bake in order to promote the crosslinking reaction in order to prevent mixing with the upper layer resist. The baking temperature is particularly preferably 200 to 300 ° C. within the range of 80 to 500 ° C., and the baking time is preferably within the range of 10 to 300 seconds. Although the thickness of this lower layer film is appropriately selected, it is preferably 30 to 20,000 nm, particularly 50 to 15,000 nm. After forming the lower layer film, in the case of a two-layer process, a silicon-containing resist layer thereon, or a single-layer resist made of ordinary hydrocarbons, in the case of a three-layer process, a silicon-containing intermediate layer is further formed thereon, and further thereon A single-layer resist layer not containing silicon is produced.
In this case, a well-known thing can be used as a photoresist composition for forming this resist layer.

  As a silicon-containing resist composition for a two-layer process, a silicon atom-containing polymer such as a polysilsesquioxane derivative or a vinylsilane derivative is used as a base polymer from the viewpoint of oxygen gas etching resistance, and further an organic solvent, an acid generator If necessary, a positive photoresist composition containing a basic compound or the like is used. In addition, as a silicon atom containing polymer, the well-known polymer used for this kind of resist composition can be used.

  A polysilsesquioxane-based intermediate layer is preferably used as the silicon-containing intermediate layer for the three-layer process. By providing the intermediate layer with an effect as an antireflection film, reflection can be suppressed.

  For 193 nm exposure, if a material containing many aromatic groups and having high substrate etching resistance is used as the lower layer film, the k value increases and the substrate reflection increases, but the substrate reflection is reduced by suppressing the reflection in the intermediate layer. .5% or less.

  As an intermediate layer having an antireflection effect, polysilsesquioxane that is crosslinked with acid or heat by introducing a light-absorbing group having a phenyl group or a silicon-silicon bond is preferably used for 193 nm exposure. .

  In addition, an intermediate layer formed by a chemical vapor deposition (CVD) method can also be used. A SiON film is known as an intermediate layer having a high effect as an antireflection film produced by a CVD method. The formation of the intermediate layer by spin coating is simpler and more cost-effective than CVD. The upper layer resist in the three-layer process may be either a positive type or a negative type, and the same one as a commonly used single layer resist can be used.

The underlayer film of the present invention can also be used as an antireflection film for a normal single layer resist. Since the underlayer film of the present invention is excellent in etching resistance for the base processing, it can be expected to function as a hard mask for the base processing.
The polyimide used in the present invention and the lower layer film made thereof are irradiated with high energy rays such as radiation, whereby the alicyclic structure is dehydrogenated, the carbon content is increased, and the etching resistance is improved.

When forming a resist layer with the said photoresist composition, a spin coat method is used preferably similarly to the case where the said lower layer film is formed. Pre-baking is performed after spin-coating the resist composition, and a range of 10 to 300 seconds at 80 to 180 ° C. is preferable. Thereafter, exposure is performed according to a conventional method, post-exposure baking (PEB), and development is performed to obtain a resist pattern. The thickness of the resist film is not particularly limited, but is preferably 30 to 500 nm, particularly 50 to 400 nm.
Examples of the exposure light include high energy rays having a wavelength of 300 nm or less, specifically, excimer lasers of 248 nm, 193 nm, and 157 nm, soft X-rays of 3 to 20 nm, electron beams, and X-rays.

Next, etching is performed using the obtained resist pattern as a mask. The lower layer film etching in the two-layer process is performed using oxygen gas. In addition to oxygen gas, inert gases such as He and Ar, and CO, CO ₂ , NH ₃ , SO ₂ , N ₂ , NO _{2, and} H ₂ gas can be added without using oxygen gas. Etching can also be performed using only CO, CO ₂ , NH ₃ , N ₂ , NO _{2, and} H ₂ gas. In particular, the latter gas is used for side wall protection for preventing undercut of the pattern side wall. In the etching of the intermediate layer in the three-layer process, the intermediate layer is processed by using a fluorocarbon gas with the resist pattern as a mask. Next, the oxygen gas etching is performed, and the lower layer film is processed using the intermediate layer pattern as a mask.

The next substrate to be processed can also be etched by a conventional method. For example, if the substrate is SiO ₂ or SiN, etching mainly using a chlorofluorocarbon gas, and if p-Si, Al, or W is chlorine or bromine, Etching is mainly performed. When the substrate processing is etched with chlorofluorocarbon gas, the silicon-containing resist in the two-layer resist process and the silicon-containing intermediate layer in the three-layer process are peeled off simultaneously with the substrate processing. When the substrate is etched with a chlorine-based or bromine-based gas, the silicon-containing resist layer or the silicon-containing intermediate layer needs to be separated by dry etching using a chlorofluorocarbon-based gas after processing the substrate.

The underlayer film of the present invention is characterized by excellent etching resistance of these substrates to be processed.
The substrate to be processed is formed on the substrate. There is no particular limitation on the substrate, and Si, α-Si, p-Si, SiO ₂ , SiN, SiON, W, TiN, Al, etc. may be made of a material different from the film to be processed (substrate to be processed). Used. Various low-k films such as Si, SiO ₂ , SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si, and their stopper films are used as the work film. Usually, it can be formed to a thickness of 50 to 10,000 nm, particularly 100 to 5,000 nm.

  Hereinafter, the present invention will be described specifically by way of examples. However, this invention is not restrict | limited at all by these Examples.

Evaluation of the resin obtained by the Example and the comparative example was performed as follows.
(1) Sublimation Evaluation Using a calorimeter measuring device (TGA) manufactured by Shimadzu Corporation, the weight reduction rate was measured when the temperature was raised from 40 ° C. to 400 ° C. at 10 ° C./min.

<Reference Example 1>
Synthesis of 1,2,4,5-cyclohexanetetracarboxylic dianhydride Catalyst with 552 g of pyromellitic acid in a 5 liter Hastelloy (HC22) autoclave and rhodium on activated carbon (N.E. NE Chemcat Corporation) 200 g and water 1656 g were charged, and the inside of the reactor was replaced with nitrogen gas while stirring. Next, the inside of the reactor was replaced with hydrogen gas, and the temperature of the reactor was increased to 60 ° C. with a hydrogen pressure of 5.0 MPa. The reaction was carried out for 2 hours while maintaining the hydrogen pressure at 5.0 MPa. The hydrogen gas in the reactor was replaced with nitrogen gas, the reaction solution was extracted from the autoclave, and the reaction solution was filtered while hot to separate the catalyst. The filtrate was concentrated by evaporating water under reduced pressure using a rotary evaporator to precipitate crystals. The precipitated crystals were separated into solid and liquid at room temperature and dried to obtain 481, g (yield: 85.0%) of 1,2,4,5-cyclohexanetetracarboxylic acid.
Subsequently, 450 g of the obtained 1,2,4,5-cyclohexanetetracarboxylic acid and 4000 g of acetic anhydride were charged into a 5-liter glass separable flask (with Dimroth condenser), and the inside of the reactor was stirred. Replaced with nitrogen gas. The temperature was raised to the reflux temperature of the solvent under a nitrogen gas atmosphere, and the solvent was refluxed for 10 minutes. While stirring, the mixture was cooled to room temperature to precipitate crystals. The precipitated crystals were separated into solid and liquid and dried to obtain primary crystals. Further, the separated mother liquor was concentrated under reduced pressure using a rotary evaporator to precipitate crystals. The crystals were separated into solid and liquid and dried to obtain secondary crystals. The primary crystal and the secondary crystal were combined to obtain 375 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (anhydrous yield of 96.6%).

<Reference Example 2>
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 10.0 g (0.05 mol) of 4,4′-diaminodiphenyl ether under nitrogen flow And 85 g of N-methyl-2-pyrrolidone as a solvent were dissolved and then 11.2 g (0.05 mol) of 1,2,4,5-cyclohexanetetracarboxylic dianhydride synthesized in Reference Example 1. Was kept in a solid state at room temperature over 1 hour and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. Then, an organic solvent solution of polyimide (PI-01) was taken out. The obtained organic solvent solution of polyimide was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772, 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula (3). It was.

The glass transition temperature of the obtained film was 315 ° C. Moreover, when the total light transmittance of this film was measured with a haze meter (Nippon Denshoku Co., Ltd. Z-Σ80) in accordance with JIS K7105, it showed a high value of 90%.
This polyimide film was heat treated in air at 220 ° C. for 4 hours, and the total light transmittance before and after the heat treatment was measured. However, there was no change at 90%, and no coloration was observed even by visual observation. In addition, the polyimide film was irradiated with a 200 W high-pressure mercury lamp as a light source for 1000 hours in the air (temperature: 60 ° C.) and subjected to high-energy light treatment, and the total light transmittance was measured similarly. No change was observed, and no coloration was observed by visual observation.

<Reference Example 3>
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 10.0 g (0.05 mol) of 4,4′-diaminodiphenyl ether under nitrogen flow Then, 85 g of N-methyl-2-pyrrolidone as a solvent was added and dissolved, and then 12.3 g (0.05 mol) of cyclopentane-1,2,3,4-tetracarboxylic acid (product of Aldrich) was added at room temperature. The solution was added in portions over 1 hour with stirring at room temperature and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 7 hours, and xylene was refluxed with a Dean Stark to separate the azeotropic product water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. The polyimide organic solvent solution (PI-02) was taken out. The obtained organic solvent solution of polyimide was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772, 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula (4). It was.

<Reference Example 4>
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 18.4 g of 4,4′-bis (4-aminophenoxy) biphenyl in a nitrogen stream. (0.05 mol) and 85 g of N-methyl-2-pyrrolidone as a solvent were dissolved, and then 11.2 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride synthesized in Reference Example 1. (0.05 mol) was charged in portions at room temperature over 1 hour, and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. The polyimide organic solvent solution (PI-03) was taken out. The obtained organic solvent solution of polyimide was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772, 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula (5). It was.

<Reference Example 5>
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 4,4′-bis (p-phenylenediisopropylidene) dianiline 17 under a nitrogen stream .1, 2 g (0.05 mol) and 85 g of N-methyl-2-pyrrolidone as a solvent were dissolved, and then 1,2,4,5-cyclohexanetetracarboxylic dianhydride 11 synthesized in Reference Example 1 was used. .2 g (0.05 mol) was charged in portions at room temperature over 1 hour and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. Then, an organic solvent solution of polyimide (PI-04) was taken out. The obtained organic solvent solution of polyimide was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772, 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula (6). It was.

<Reference Example 6>
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 17.4 g of 9,9′-bis (4-aminophenyl) fluorene in a nitrogen stream (0.05 mol) and 85 g of a mixed solvent of dimethylacetamide / γ-butyrolactone (weight ratio 1/4) as a solvent were dissolved, and then 1,2,4,5-cyclohexanetetracarboxylic synthesized in Reference Example 1 was used. 11.2 g (0.05 mol) of acid dianhydride was added in portions over 1 hour while remaining solid at room temperature, and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. Then, an organic solvent solution of polyimide (PI-05) was taken out. The obtained organic solvent solution of polyimide was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772, 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula (7). It was.

<Reference Example 7>
-Synthesis example of DMN resin (1,5DMN-R) In a four-necked flask (2 L) equipped with a Jim Roth condenser, thermometer, and stirring blade, in a nitrogen stream, Mitsubishi Gas Chemical's 1,5- Dimethylnaphthalene (1,5DMN) (218 g, 1.4 mol), 40% aqueous formalin solution (420 g, 5.6 mol) manufactured by Mitsubishi Gas Chemical Co., Ltd., 98% sulfuric acid (194 g) manufactured by Kanto Chemical Co., Ltd. were charged at 100 ° C. for 7 hours under normal pressure. At reflux. After dilution with ethylbenzene, neutralization and water washing were performed, and the solvent was removed and 1,5DMN was removed under reduced pressure to obtain 250 g of a light brown solid (1,5DMN-R). It was Mn: 550, Mw: 1130, and Mw / Mn: 2.05 as a result of the GPC measurement.

<Reference Example 8>
(2) Modified resin synthesis example 1
In a four-necked flask (0.5 L) equipped with a Jim Roth condenser, thermometer, and stirring blade, 1,5 DMN-R (90 g, 0.5 mol), α-naphthol (71. 1 g, 0.49 mol) and paratoluenesulfonic acid (0.024 g) were added, and the reaction was allowed to warm to 185 ° C. for 4 hours. After diluting the solvent, neutralization and water washing were performed, and the solvent was removed and α-naphthol was removed under reduced pressure to obtain 160 g (NF-1) of a light brown solid. As a result of GPC measurement, Mn: 848, Mw: 1630, Mw / Mn: 1.93, and the hydroxyl value was 175 mgKOH / g.

Examples 1 to 7, Comparative Examples 1 and 2
Underlayer film forming compositions having the compositions shown in Table 1 were prepared. Next, the lower layer film-forming composition solution was spin-coated on a silicon substrate and baked at 250 to 300 ° C. for 90 seconds to obtain a lower layer film having a thickness of 200 nm as the lower layer film. A. The complex refractive index of the lower layer film is obtained by measuring at a wavelength of 193 nm with a variable angle ellipsometer (VASE) manufactured by Woollam and fitting the absorption with a Gaussian oscillator by approximating the absorption with a General Oscillator Model. A refractive index n and an extinction coefficient k were obtained. The results are shown in Table 1. The etching test was performed under the conditions shown below, and the results are shown in Table 1.

Etching equipment: RIE-10NR manufactured by Samco International
Output: 50W
Pressure: 20Pa
Time: 2min
Etching gas
(1) CF ₄ gas flow rate: 10 (sccm)
(2) Ar gas flow rate: CF ₄ gas flow rate: O ₂ gas flow rate = 50: 5: 5 (sccm)

Acid generator: Ditertiary butyl diphenyliodonium nonafluoromethanesulfonate (DTDDPI) manufactured by Midori Chemical Co., Ltd.
Cross-linking agent: Nikalac MX270 (Nikarac) manufactured by Sanwa Chemical Co., Ltd.
Organic solvent: propylene glycol monomethyl ether acetate (PGMEA),
Cyclohexanone (CHN)
PHS: Polyhydroxystyrene (manufactured by Aldrich)
Novolak: PSM4357 manufactured by Gunei Chemical Co., Ltd.

Example 8
Next, the lower layer film-forming composition solution (Example 7) was applied onto a 300 nm thick Si substrate and baked at 300 ° C. for 120 seconds to form an 80 nm thick lower layer film. An ArF resist solution was applied thereon and baked at 130 ° C. for 60 seconds to form a 150 nm-thick photoresist layer. The ArF resist solution was prepared by blending 5 parts of the compound of the following formula (8), 1 part of triphenylsulfonium nonafluoromethanesulfonate, 2 parts of tributylamine, and 92 parts of PGMEA.
Next, it is exposed with an electron beam lithography apparatus (manufactured by Elionix; ELS-7500, 50 keV), baked (PEB) at 115 ° C. for 90 seconds, and developed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 60 seconds. As a result, a positive pattern was obtained. Table 2 shows the result of observing the pattern shape of 60 nm L / S (1: 1) of the obtained pattern.

Comparative Example 3
Table 2 shows the results of evaluation conducted in the same manner as in Example 8 except that no lower layer film was formed.

(In the formula (8), 40, 40, and 20 indicate the ratio of each structural unit, and do not indicate a block copolymer.)

  Next, the resist pattern obtained after the electron beam exposure and development was transferred to the lower layer film under the following conditions. Etching conditions are as shown below.

Etching equipment: RIE-10NR manufactured by Samco International
Output: 50W
Pressure: 20Pa
Time: 2min
Etching gas Ar gas flow rate: CF ₄ gas flow rate: O ₂ gas flow rate = 50: 5: 5 (sccm)

  The pattern cross section was observed with an electron microscope (S-4800) manufactured by Hitachi, Ltd., and the shapes were compared.

  The resist shape after development in multilayer resist processing, the shape of the lower layer film after oxygen etching and substrate processing etching are also good, and the shape after development and etching after substrate processing are also good when used as a single layer resist hard mask It was confirmed that

Claims (7)

A composition for forming a lower layer film for lithography, comprising a polyimide having a repeating unit represented by the general formula (1) and an organic solvent.
(In the formula (1), R is a tetravalent group derived from cyclohexane. Φ is a structural unit having 2 to 39 carbon atoms, an aliphatic structural unit, an alicyclic structural unit, an aromatic structural unit, It is an organosiloxane structural unit, or a structural unit comprising a combination or repetition thereof, and the main chain of Φ has —O—, —SO ₂ —, —CO—, —CH ₂ —, —C (CH ₃ ) ₂ —. , -C ₂ H ₄ O-, and at least one partial structure selected from the group consisting of -S- may intervene.) Formula (1) composition for forming an underlayer film for lithography according to claim 1, wherein Φ is a divalent group having a fluorene bisphenyl structure in. The underlayer film forming composition for lithography according to claim 1 or 2 , comprising a modified dimethylnaphthalene formaldehyde resin having a structural unit represented by the following general formula (2) in the molecule.
(In formula (2), each R independently represents a functional group selected from the group consisting of a hydrogen atom, a methoxymethyl group, a hydroxymethyl group, and a methylene group, X is — (O ₂ CH ₂ ) t—, 1 ≦ n ≦ 4, 0 ≦ t ≦ 2, Y is a saturated aliphatic hydrocarbon having 1 to 3 carbon atoms, and Y may be bonded to form a ring structure. The underlayer film forming composition for lithography according to any one of claims 1 to 3 , comprising an acid generator. The underlayer film forming composition for lithography according to any one of claims 1 to 4 , comprising a crosslinking agent. An underlayer film for lithography formed from the underlayer film forming composition for lithography according to any one of claims 1 to 5 . A lower layer film is formed on the substrate using the lower layer film forming composition for lithography according to any one of claims 1 to 5 , and at least one photoresist layer is formed on the lower layer film. After irradiating the desired region of the photoresist layer with radiation and developing the resist pattern by alkali development, the lower layer film is etched with plasma containing at least oxygen gas using the resist pattern as a mask, and the resist pattern is formed on the lower layer film. A method for forming a multi-layer resist pattern, comprising transferring.