New onium salts and photoacid generators

Abstract

The present invention functions as a photoacid generator; and this photoacid generator provides a chemically amplified photoresist composition by being combined with a component that is a resin, the solubility of which in an alkali is increased by the action of an acid that is generated when irradiated with an active energy ray such as an electron beam or light, or the like. The present invention is an onium salt which is represented by general formula (1), wherein among two kinds of isomers of an anion structure, namely among facial isomers and meridional isomers, the proportion of the facial isomers is 15.0% by weight or less. (1): ((R2)n+1-E)+ ((R1)3(F)3P)-

Description

[Technical field]

[0001] The present invention relates to a novel onium salt and a novel onium salt-type photoacid generator, and more particularly to a photoacid generator suitable for use in a chemically amplified resist resin composition used in semiconductor pattern formation. [Background technology]

[0002] Conventionally, photoacid generators that generate acid when irradiated with active energy rays such as light or electron beams are known. Furthermore, these photoacid generators are widely known as photoacid generators for resists (Patent Documents 1 and 2).

[0003] The anions described in these specifications include sulfonates, BF4 - , PF6 - , AsF6 - , SbF6 - In view of the toxicity of As and Sb, in resist materials, especially in the field of semiconductor resists, AsF6 - , SbF6 - can be avoided, BF4 - , PF6 - However, the acid strength was weak and the usability was extremely poor. Furthermore, a special phosphorus-based photoacid generator has been described, but this also does not have sufficient sensitivity (Patent Document 3). A method for producing this special phosphorus-based photoacid generator has also been described, but even with this, a useful photoacid generator could not be found (Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2002-193925 [Patent Document 2] Japanese Patent Application Publication No. 2001-354669 [Patent Document 3] WO2005 / 116038 publication [Patent Document 4] Special Publication No. 2004-533473 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, the present invention has been completed based on the discovery that by having a specific anion structure and further controlling the stereoisomers of that anion structure within a certain range, a specifically high sensitivity is exhibited when used as a resist material. [Means for solving the problem]

[0006] The present inventors have synthesized an onium salt represented by general formula (1), in which the proportion of the facial isomer among two types of isomers, facial and meridional, of the anionic structure is 15.0% by weight or less, and have found that the onium salt is suitable for the above-mentioned purpose. [(R 2 ) n+1 -E] + [ (R 1 )3(F)3P] - (1)

[0007] In formula (1), R 1 is an alkyl group having 1 to 18 carbon atoms substituted with a halogen atom, or an aryl group having 6 to 18 carbon atoms (not including the number of carbon atoms of the following substituents). Some of the hydrogen atoms in the aryl group may be substituted with an alkyl group having 1 to 18 carbon atoms, a halogen atom, an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom, an alkenyl group having 2 to 18 carbon atoms, or an alkynyl group having 2 to 18 carbon atoms; E represents an element of group 15 to 17 (IUPAC notation) with a valence of n, where n is an integer from 1 to 3, and R 2 is an organic group bonded to E, and R 2 The number of is n+1, and (n+1) R 2 may be the same or different, and two or more R 2may form a ring structure containing the element E directly or via -O-, -S-, -SO-, -SO2-, -NH-, -CO-, -COO-, -CONH-, an alkylene group or a phenylene group. Effect of the Invention

[0008] The onium salt of the present invention functions as a photoacid generator, and further, by combining this photoacid generator with a component such as a resin whose solubility in alkali increases due to the action of an acid generated by irradiation with active energy rays such as light or electron beams, a chemically amplified photoresist composition can be produced. The onium salt of the present invention exerts a unique effect when used for this purpose.

[0009] In other words, the chemically amplified positive photoresist composition and the chemically amplified negative photoresist composition using the acid generator containing the onium salt of the present invention make it possible to obtain a highly sensitive resist (enabling pattern formation with a lower exposure dose than conventional ones). Furthermore, the chemically amplified positive photoresist composition and the chemically amplified negative photoresist composition of the present invention provide a good resist pattern shape. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail.

[0011] The onium salt of the present invention is represented by the following general formula (1).

[0012] An onium salt represented by the general formula (1), in which the proportion of the facial isomer among two types of isomers, facial and meridional, of the anion structure is 15.0% by weight or less.

[0013] [(R 2 ) n+1 -E] + [ (R 1 )3(F)3P] - (1)

[0014] In formula (1), R1 is an alkyl group having 1 to 18 carbon atoms substituted with a halogen atom, or an aryl group having 6 to 18 carbon atoms (not including the number of carbon atoms of the following substituents). Some of the hydrogen atoms in the aryl group may be substituted with an alkyl group having 1 to 18 carbon atoms, a halogen atom, an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom, an alkenyl group having 2 to 18 carbon atoms, or an alkynyl group having 2 to 18 carbon atoms; E represents an element of group 15 to 17 (IUPAC notation) with a valence of n, where n is an integer from 1 to 3, and R 2 is an organic group bonded to E, and R 2 The number of is n+1, and (n+1) R 2 may be the same or different, and two or more R 2 may form a ring structure containing the element E directly or via -O-, -S-, -SO-, -SO2-, -NH-, -CO-, -COO-, -CONH-, an alkylene group or a phenylene group.

[0015] In the anion (B) of the onium salt (A) of the present invention, P represents a phosphorus atom and F represents a fluorine atom. 1 is an alkyl group having 1 to 18 carbon atoms substituted with a halogen atom, or an aryl group having 6 to 18 carbon atoms (not including the number of carbon atoms of the following substituents). Some of the hydrogen atoms in the aryl group may be substituted with an alkyl group having 1 to 18 carbon atoms, a halogen atom, an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom, an alkenyl group having 2 to 18 carbon atoms, or an alkynyl group having 2 to 18 carbon atoms.

[0016] This anion (B) has P as the central element, F, and R 1 In this case, there are two types of isomers: facial isomers, in which the same ligands are mutually cis-configured, and meridional isomers, in which the same ligands are on the same plane.

[0017] When the onium salt (A) functions as an acid generator, the anion (B) protonated functions as an acid, so that it is extremely important to control the ratio of the two isomers. By setting the ratio of the facial isomer to 15.0% by weight or less, a dramatically high-sensitivity resist (pattern formation is possible with a lower exposure dose than conventional resists) can be created. The ratio of the facial isomer to the meridional isomer is more preferably in the range of 0.1 to 15.0% by weight, and most preferably 0.5 to 10.0% by weight.

[0018] R 1 is an alkyl group having 1 to 18 carbon atoms substituted with a halogen atom, or an aryl group having 6 to 18 carbon atoms (not including the number of carbon atoms of the following substituents). Some of the hydrogen atoms in the aryl group may be substituted with an alkyl group having 1 to 18 carbon atoms, a halogen atom, an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom, an alkenyl group having 2 to 18 carbon atoms, or an alkynyl group having 2 to 18 carbon atoms. Examples of these substituents are described below in R 2 Among these, a perfluoroalkyl group and a phenyl group substituted with a fluorine atom are preferred, and specifically, a pentafluoroethyl group, a heptafluoro-n-propyl group, a nonafluoro-n-butyl group, a heptafluoro-i-propyl group, a trifluoromethyl group, and the like are more preferred.

[0019] To control the ratio of the two isomers, facial and meridional, for example, the precursor phosphorane ((R 1 By optimizing the polarity of the solvent, the amount (concentration) of the solvent and substrate, and the reaction temperature when reacting 3(F)2P) with a fluorinating agent, it is possible to synthesize the desired isomer. Examples of fluorinating agents include hydrogen fluoride and metal fluorides (sodium fluoride, potassium fluoride).

[0020] The cation (C) of the onium salt (A) is a cationic moiety of the general formula (1), E represents an element of Group 15 to Group 17 (IUPAC notation) with a valence of n, n being an integer of 1 to 3, and R 2 is an organic group bonded to E, and R 2 The number of is n+1, and (n+1) R 2 may be the same or different, and two or more R 2 may form a ring structure containing the element E directly or via -O-, -S-, -SO-, -SO2-, -NH-, -CO-, -COO-, -CONH-, an alkylene group or a phenylene group.

[0021] Specific examples of E include element symbols such as N, O, F, P, S, Cl, As, Se, Br, Sb, Te, and I. Among these, preferred elements are S, I, N, and P. Corresponding cations (C) include sulfonium, iodonium, ammonium, and phosphonium. More preferred elements are S and I. Corresponding cations (C) include sulfonium and iodonium.

[0022] R 2 R represents an organic group bonded to E and may be the same or different. 2 Examples of the aryl group include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, and an aryl group having 6 to 18 carbon atoms. The aryl group can further include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, a nitro group, a hydroxyl group, a cyano group, -OR 5 an alkoxy group or an aryloxy group represented by the formula: 6 an alkylthio group or an arylthio group represented by the formula: 7 An acyl group represented by CO-, R 8 Acyloxy group represented by COO-, -NR 9 R 10 or a halogen atom.

[0023] Above R 2Examples of the alkyl group having 1 to 18 carbon atoms in the formula (I) include linear alkyl groups (methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, and the like), branched alkyl groups (isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, 2-ethylhexyl, 1,1,3,3-tetramethylbutyl, and the like), cycloalkyl groups (cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like), bridged cyclic alkyl groups (norbornyl, adamantyl, pinanyl, and the like), and arylalkyl groups (benzyl, naphthylmethyl, phenethyl, benzhydryl, phenacyl, and the like).

[0024] Above R 2 Examples of the alkenyl group having 2 to 18 carbon atoms in the formula (I) include linear or branched alkenyl groups (vinyl, allyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, etc.), cycloalkenyl groups (2-cyclohexenyl, 3-cyclohexenyl, etc.), and arylalkenyl groups (styryl, cinnamyl, etc.).

[0025] Above R 2In the above, examples of the aryl group having 6 to 18 carbon atoms (excluding the number of carbon atoms of the following substituents) include monocyclic aryl groups (phenyl, etc.), condensed polycyclic aryl groups (naphthyl, anthracenyl, phenanthrenyl, anthraquinolyl, fluorenyl, naphthoquinolyl, etc.), and aromatic heterocyclic hydrocarbon groups (monocyclic heterocycles such as thienyl, furanyl, pyranyl, pyrrolyl, oxazolyl, thiazolyl, pyridyl, pyrimidyl, pyrazinyl, etc.; and indolyl, benzoyl, zofuranyl, isobenzofuranyl, benzothienyl, isobenzothienyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenothiazinyl, phenazinyl, xanthenyl, thianthrenyl, phenoxazinyl, phenoxathiinyl, chromanyl, isochromanyl, coumarinyl, dibenzothienyl, xanthonyl, thioxanthonyl, dibenzofuranyl, and other condensed polycyclic heterocycles.

[0026] In addition to the above, the aryl group may be an aryl group in which some of the hydrogen atoms are substituted with an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, a nitro group, a hydroxyl group, a cyano group, -OR 5 an alkoxy group or an aryloxy group represented by the formula: 6 an alkylthio group or an arylthio group represented by the formula: 7 An acyl group represented by CO-, R 8 Acyloxy group represented by COO-, -NR 9 R 10 or a halogen atom.

[0027] In the above substituents, -OR 5 an alkoxy group represented by the formula -SR 6 an alkylthio group represented by R 7 An acyl group represented by CO-, R 8 Acyloxy group represented by COO-, -NR 9 R 10 R of the amino group represented by 5 ~R 10Examples of the alkyl group include alkyl groups having 1 to 8 carbon atoms, and specific examples of the alkyl groups include those having 1 to 8 carbon atoms among the above alkyl groups.

[0028] In the above substituents, -OR 5 an aryloxy group represented by -SR 6 an arylthio group represented by R 7 An acyl group represented by CO-, R 8 Acyloxy group represented by COO-, -NR 9 R 10 R of the amino group represented by 5 ~R 10 Examples of the aryl group include aryl groups having 6 to 18 carbon atoms, and specific examples thereof include the above-mentioned aryl groups having 6 to 18 carbon atoms.

[0029] -OR 5 Examples of the alkoxy group represented by the formula (I) include methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, iso-pentoxy, neo-pentoxy, and 2-methylbutoxy. -OR 5 Examples of the aryloxy group represented by the formula (I) include phenoxy and naphthoxy. -SR 6 Examples of the alkylthio group represented by the formula (I) include methylthio, ethylthio, butylthio, hexylthio, and cyclohexylthio. -SR 6 Examples of the arylthio group represented by the formula (I) include phenylthio, naphthylthio, biphenylthio, and 2-thioxanthonylthio. R 7 Examples of the acyl group represented by CO- include acetyl, propanoyl, butanoyl, pivaloyl, and benzoyl. R 8 Examples of the acyloxy group represented by COO-- include acetoxy, butanoyloxy, and benzoyloxy. -NR 9 R 10Examples of the amino group represented by the formula (I) include methylamino, ethylamino, propylamino, dimethylamino, diethylamino, methylethylamino, dipropylamino, dipropylamino, and piperidino. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0030] Above R 2 Among these, preferred are an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, a nitro group, a hydroxyl group, an alkyl group having 1 to 18 carbon atoms, -OR 5 an alkoxy group represented by the formula -SR 6 an arylthio group represented by R 7 An acyl group represented by CO-, R 8 It is an acyloxy group represented by COO- or an aryl group having 6 to 18 carbon atoms substituted with a chlorine atom. More preferred are alkyl groups having 1 to 18 carbon atoms, phenyl groups, hydroxyl groups, alkyl groups having 1 to 18 carbon atoms, -OR 5 an alkoxy group represented by the formula -SR 6 and phenyl groups substituted with an arylthio group, an acetyl group, a benzoyl group, or an acetoxy group, represented by the following formula:

[0031] Also, two or more R 2 may form a ring structure containing the element E directly or via -O-, -S-, -SO-, -SO2-, -NH-, -CO-, -COO-, -CONH-, an alkylene group or a phenylene group.

[0032] Specific examples of the cation (C) are shown below.

[0033] Specific examples of ammonium ions include tetraalkylammonium ions such as tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, triethylmethylammonium, and tetraethylammonium; pyrrolidinium ions such as N,N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, and N,N-diethylpyrrolidinium; imidazolinium ions such as N,N'-dimethylimidazolinium, N,N'-diethylimidazolinium, N-ethyl-N'-methylimidazolinium, 1,3,4-trimethylimidazolinium, and 1,2,3,4-tetramethylimidazolinium; and N,N'-dimethyltetrahydropyrrolidinium. tetrahydropyrimidiniums such as midinium; morpholiniums such as N,N'-dimethylmorpholinium; piperidiniums such as N,N'-diethylpiperidinium; pyridiniums such as N-methylpyridinium, N-benzylpyridinium, and N-phenacylpyridinium; imidazoliums such as N,N'-dimethylimidazolium; quinoliums such as N-methylquinolium, N-benzylquinolium, and N-phenacylquinolium; isoquinoliums such as N-methylisoquinolium; thiazoniums such as benzylbenzothiazonium and phenacylbenzothiazonium; and acridiums such as benzylacridium and phenacylacridium.

[0034] Specific examples of phosphonium ions include tetraarylphosphonium ions such as tetraphenylphosphonium, tetra-p-tolylphosphonium, tetrakis(2-methoxyphenyl)phosphonium, tetrakis(3-methoxyphenyl)phosphonium, and tetrakis(4-methoxyphenyl)phosphonium; triarylphosphonium ions such as triphenylbenzylphosphonium, triphenylphenacylphosphonium, triphenylmethylphosphonium, and triphenylbutylphosphonium; and tetraalkylphosphonium ions such as triethylbenzylphosphonium, tributylbenzylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, triethylphenacylphosphonium, and tributylphenacylphosphonium.

[0035] Specific examples of sulfonium ions include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris(4-methoxyphenyl)sulfonium, 1-naphthyldiphenylsulfonium, 2-naphthyldiphenylsulfonium, tris(4-fluorophenyl)sulfonium, tri-1-naphthylsulfonium, tri-2-naphthylsulfonium, tris(4-hydroxyphenyl)sulfonium, 4-(phenylthio)phenyldiphenylsulfonium, 4-(p-tolylthio)phenyldi-p-tolylsulfonium, 4-(4-methoxyphenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenylbis(4-fluorophenyl)sulfonium, 4-(phenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenyldi-p-tolylsulfonium, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium, [4-(2-thioxanthonyl bis[4-(thio)phenyl]diphenylsulfonium, bis[4-(diphenylsulfonio)phenyl]sulfide, bis[4-{bis[4-(2-hydroxyethoxy)phenyl]sulfonio}phenyl]sulfide, bis{4-[bis(4-fluorophenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methylphenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methoxyphenyl)sulfonio]phenyl}sulfide, 4-(4-benzoyl-2-chlorophenyl)sulfonium, 4-(4-benzoyl-2-chlorophenylthio)phenyldiphenylsulfonium, 4-(4-benzoylphenylthio)phenylbis(4-fluorophenyl)sulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracen-2-yldi-p-tolylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-Dihydroanthracen-2-yldiphenylsulfonium, 2-[(di-p-tolyl)sulfonio]thioxanthone, 2-[(diphenyl)sulfonio]thioxanthone, 4-(9-oxo-9H-thioxanthen-2-yl)thiophenyl-9-oxo-9H-thioxanthen-2-yl phenylsulfonium, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldi-p-tolylsulfonium, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldiphenylsulfonium, 4-[4-(benzoylphenylthio)]phenyldi-p-tolylsulfonium, 4-[4-(benzoylphenylthio)]phenyldiphenylsulfonium, 5-(4-methoxyphenyl)thianthrenium, 5-phenylthianthrenium, 5-tolylthianthreneium, 5-(4-ethoxyphenyl)thianthrenium, 5-(2,4,6-trimethylphenyl)thianthrenium and other triarylsulfoniums;diphenylphenacylsulfonium, diphenyl4-nitrophenacylsulfonium, diphenylbenzylsulfonium, diphenylmethylsulfonium and other diarylsulfoniums;phenylmethylbenzylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, 4-methoxyphenylmethylbenzylsulfonium, 4-acetoxyphenylmethylbenzylsulfonium, 4-acetoxyphenyldimethylsulfonium, 4-hydroxyphenyl(1-naphthylmethyl)methylsulfonium, 2-naphthylmethylbenzylsulfonium, 4-hydroxyphenyl(4-nitrobenzyl ... Monoarylsulfonium such as (1-ethoxycarbonyl)ethylsulfonium, phenylmethylphenacylsulfonium, 4-hydroxyphenylmethylphenacylsulfonium, 4-methoxyphenylmethylphenacylsulfonium, 4-acetoxyphenylmethylphenacylsulfonium, 2-naphthylmethylphenacylsulfonium, 2-naphthyloctadecylphenacylsulfonium, and 9-anthracenylmethylphenacylsulfonium; and trialkylsulfonium such as dimethylphenacylsulfonium, phenacylstetrahydrothiophenium, dimethylbenzylsulfonium, benzyltetrahydrothiophenium, and octadecylmethylphenacylsulfonium.

[0036] Specific examples of iodonium ions include diphenyliodonium, di-p-tolyliodonium, di(4-tert-butylphenyl)iodonium, di(4-dodecylphenyl)iodonium, di(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, di(4-decyloxyphenyl)iodonium, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium, 4-isopropylphenyl(p-tolyl)iodonium, phenyl(2,4,6-trimethoxyphenyl)iodonium, and 4-isobutylphenyl(p-tolyl)iodonium.

[0037] The onium salt of the present invention represented by formula (1) can be produced by a double decomposition method. The double decomposition method is described in, for example, Shin Jikken Kagaku Koza, Vol. 14-I (1978, Maruzen), p. 448; Advance in Polymer Science, 62, 1-48 (1984); Shin Jikken Kagaku Koza, Vol. 14-III (1978, Maruzen), pp. 1838-1846; Organic Sulfur Chemistry (Synthetic Reactions, 1982, Kagaku Dojin), Chapter 8, pp. 237-280; Nihon Kagaku Zasshi, 87, (5), 74 (1966); JP-A Nos. 64-45357, 61-212554, 61-100557, 5-4996, 7-82244, 7-82245, 58-210904, and 6-184170. First, the F of the onium cation is reacted with the cation of - , Cl - , Br - , I - Halogen ion salts such as;OH - Salt;ClO4 - Salt; FSO3 - , ClSO3 - , CH3SO3 - , C6H5SO3 - , CF3SO3 - Salts with sulfonic acid ions such as HSO4 - , SO4 2- Salts with sulfate ions such as HCO3 - , CO3 2- , and other carbonate ions;H2PO4 - , HPO4 2- , PO4 3-A salt with phosphate ions such as phosphate ions is prepared, and this is added to an alkali metal salt, an alkaline earth metal salt, or a quaternary ammonium salt of an anion constituting the onium salt represented by formula (1) in a solvent and an aqueous solution to cause double decomposition. Water or an organic solvent can be used as the solvent. Organic solvents include hydrocarbons (hexane, heptane, toluene, xylene, etc.), cyclic ethers (tetrahydrofuran and dioxane, etc.), chlorine-based solvents (chloroform and dichloromethane, etc.), alcohols (methanol, ethanol, isopropyl alcohol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), nitriles (acetonitrile, etc.), and polar organic solvents (dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, etc.). These solvents may be used alone or in combination of two or more.

[0038] The target onium salt thus produced is separated as a crystal or oil. In the case of an oil, the precipitated oil is separated from the organic solvent solution, and the organic solvent contained in the oil is distilled off to obtain the product. In the case of a crystal, the precipitated solid is separated from the organic solvent solution, and the organic solvent contained in the solid is distilled off to obtain the product. The target onium salt thus obtained can be purified, if necessary, by a method such as recrystallization or washing with water or a solvent.

[0039] Purification by recrystallization can be performed by dissolving the target onium salt in a small amount of organic solvent, and separating the target onium salt from the organic solvent by adding a poor solvent directly (or after concentrating) to the organic solvent solution containing the target onium salt to precipitate the target onium salt. The poor solvent used here includes chain ethers (diethyl ether, dipropyl ether, etc.), esters (ethyl acetate, butyl acetate, etc.), aliphatic hydrocarbons (hexane, cyclohexane, etc.), and aromatic hydrocarbons (toluene, xylene, etc.). Purification can also be performed by utilizing the difference in solubility due to temperature. Purification can be performed by recrystallization (a method that utilizes the difference in solubility due to cooling, a method of precipitating by adding a poor solvent, and a combination of these). In addition, when the target product is an oily product (not crystallized), purification can be performed by washing the oily product with water or a poor solvent.

[0040] When using the onium salt of formula (1), in order to facilitate dissolution in the chemically amplified resist composition, it may be dissolved in advance in a solvent that does not inhibit polymerization, crosslinking, deprotection reactions, etc.

[0041] Examples of the solvent include carbonates such as propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, and monophenyl ether of ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, and dipropylene glycol monoacetate. polyhydric alcohols and derivatives thereof such as ethyl formate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl pyruvate, ethyl ethoxyacetate, methyl methoxypropionate, ethyl ethoxypropionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, and other esters; and aromatic hydrocarbons such as toluene and xylene.

[0042] When a solvent is used, the proportion of the solvent is preferably 15 to 1000 parts by weight, more preferably 30 to 500 parts by weight, based on 100 parts by weight of the onium salt represented by formula (1) of the present invention. The solvents used may be used alone or in combination of two or more kinds.

[0043] By using the onium salt of the present invention as a photoacid generator and further incorporating various other ingredients, an energy ray-curable composition can be obtained. This composition can be cured by irradiating it with energy rays to obtain a cured product. The energy ray may be any ray as long as it has energy capable of inducing decomposition of the photoacid generator of the present invention, but is preferably an energy ray in the ultraviolet to visible light region (wavelength: about 100 to about 800 nm) obtained from a low-, medium-, high- or ultra-high-pressure mercury lamp, a metal halide lamp, an LED lamp, a xenon lamp, a carbon arc lamp, a fluorescent lamp, a semiconductor solid-state laser, an argon laser, a He-Cd laser, a KrF excimer laser, an ArF excimer laser, an F2 laser, etc. Incidentally, the energy ray may be a high-energy radiation such as an electron beam or an X-ray.

[0044] The irradiation time of the energy ray is affected by the intensity of the energy ray and the permeability of the energy ray to the energy ray curable composition, but about 0.1 to 10 seconds at room temperature (about 20 to 30°C) is sufficient. However, when the permeability of the energy ray is low or when the film thickness of the energy ray curable composition is thick, it may be preferable to apply a longer time. Most energy ray curable compositions are cured by cationic polymerization 0.1 seconds to several minutes after the energy ray irradiation, but if necessary, it is also possible to after-cure by heating at room temperature (about 20 to 30°C) to 200°C for several seconds to several hours after the energy ray irradiation.

[0045] Specific applications of this energy ray-curable composition include positive resists (such as connection terminals and wiring pattern formation in the manufacture of electronic components such as circuit boards, CSPs, and MEMS elements), negative resists (such as surface protective films for semiconductor elements, interlayer insulating films, and permanent film materials such as planarizing films), and the like.

[0046] Chemically amplified resist materials include (1) two-component chemically amplified positive resists whose essential components are a resin that becomes soluble in an alkaline developer by the action of acid and a photoacid generator; (2) three-component chemically amplified positive resists whose essential components are a resin that is soluble in an alkaline developer, a dissolution inhibitor that becomes soluble in an alkaline developer by the action of acid, and a photoacid generator; and (3) chemically amplified negative resists whose essential components are a resin that is soluble in an alkaline developer, a crosslinker that crosslinks the resin by heating in the presence of acid to make it insoluble in an alkaline developer, and a photoacid generator.

[0047] The above-mentioned chemically amplified positive photoresist compositions (1) and (2) contain a resin component (F) in which the onium salt (A) of the present invention, which is a compound that generates an acid upon exposure to light or radiation, functions as an acid generator and which has increased solubility in alkali due to the action of the acid.

[0048] The content of the onium salt (A) is preferably from 0.05 to 5% by weight based on the solid content of the chemically amplified positive photoresist composition.

[0049] <Resin component (F) whose solubility in alkali increases under the action of acid> The "resin (F) whose solubility in alkali increases under the action of an acid" (herein referred to as "component (F)") used in the chemically amplified positive photoresist composition of the present invention is at least one resin selected from the group consisting of novolak resins (F1), polyhydroxystyrene resins (F2), and acrylic resins (F3), or a mixed resin or copolymer thereof.

[0050] [Novolac resin (F1)] As the novolak resin (F1), a resin represented by the following general formula (b1) can be used.

[0051] [ka]

[0052] In the above general formula (b1), R1b represents an acid dissociable dissolution inhibiting group, R 2b , R 3b each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n represents the number of repeating units of the structure in the parentheses.

[0053] Furthermore, the above R 1b The acid dissociable, dissolution inhibiting group represented by the formula (I) is preferably a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, a cyclic alkyl group having 3 to 6 carbon atoms, a tetrahydropyranyl group, a tetrahydrofuranyl group, or a trialkylsilyl group.

[0054] Here, the above R 1b Specific examples of acid dissociable, dissolution inhibiting groups represented by the formula (I) include a methoxyethyl group, an ethoxyethyl group, an n-propoxyethyl group, an isopropoxyethyl group, an n-butoxyethyl group, an isobutoxyethyl group, a tert-butoxyethyl group, a cyclohexyloxyethyl group, a methoxypropyl group, an ethoxypropyl group, a 1-methoxy-1-methyl-ethyl group, a 1-ethoxy-1-methylethyl group, a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a trimethylsilyl group, and a tri-tert-butyldimethylsilyl group.

[0055] [Polyhydroxystyrene resin (F2)] As the polyhydroxystyrene resin (F2), a resin represented by the following general formula (b4) can be used.

[0056] [ka]

[0057] In the above general formula (b4), R 8b represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R 9b represents an acid dissociable, dissolution inhibiting group, and n represents the number of repeating units of the structure in parentheses.

[0058] The alkyl group having 1 to 6 carbon atoms is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, or a neopentyl group, and examples of the cyclic alkyl group include a cyclopentyl group, or a cyclohexyl group.

[0059] Above R 9b The acid dissociable dissolution inhibiting group represented by the above R 1b The same acid dissociable, dissolution inhibiting groups as those exemplified in can be used.

[0060] Furthermore, the polyhydroxystyrene resin (F2) may contain other polymerizable compounds as constituent units for the purpose of appropriately controlling the physical and chemical properties. Examples of such polymerizable compounds include known radical polymerizable compounds and anionic polymerizable compounds. For example, monocarboxylic acids such as acrylic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; methacrylic acid derivatives having a carboxyl group and an ester bond such as 2-methacryloyloxyethyl succinic acid; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate; dicarboxylic acid diesters such as diethyl maleate; vinyl group-containing aromatic compounds such as styrene and vinyl toluene; vinyl group-containing aliphatic compounds such as vinyl acetate; conjugated diolefins such as butadiene and isoprene; nitrile group-containing polymerizable compounds such as acrylonitrile; chlorine-containing polymerizable compounds such as vinyl chloride; and amide bond-containing polymerizable compounds such as acrylamide.

[0061] [Acrylic resin (F3)] As the acrylic resin (F3), resins represented by the following general formulas (b5) to (b10) can be used.

[0062] [ka]

[0063] [ka]

[0064] In the above general formulas (b5) to (b7), R 10b ~R 17b each independently represents a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, a fluorine atom, a linear fluorinated alkyl group having 1 to 6 carbon atoms, or a branched fluorinated alkyl group having 3 to 6 carbon atoms; X b forms a hydrocarbon ring having 5 to 20 carbon atoms together with the carbon atom to which it is attached, and Y b represents an aliphatic cyclic group or alkyl group which may have a substituent; n represents the number of repeating units of the structure in the parentheses; p is an integer of 0 to 4; and q is 0 or 1.

[0065] In the general formula (b8), the general formula (b9) and the general formula (b10), R 18b , R 20b and R 21b each independently represents a hydrogen atom or a methyl group; 19b are each independently a hydrogen atom, a hydroxyl group, a cyano group or a COOR 23b Group (wherein R 23b represents a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a branched alkyl group having 3 to 4 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms. 22b each independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 to 4 carbon atoms, and R 22b At least one of R is the alicyclic hydrocarbon group or a derivative thereof, or any two of R 22b are bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof together with the common carbon atom to which each is bonded, and the remaining R22b represents a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.

[0066] Of the above components (F), it is preferable to use the acrylic resin (F3).

[0067] Furthermore, the polystyrene-equivalent weight average molecular weight of component (F) is preferably 10,000 to 600,000, more preferably 50,000 to 600,000, and even more preferably 230,000 to 550,000. By adjusting the weight average molecular weight in this range, the resist resin physical properties will be excellent.

[0068] Furthermore, it is preferable that component (F) is a resin having a dispersity of 1.05 or more. Here, "dispersity" refers to the value obtained by dividing the weight average molecular weight by the number average molecular weight. By achieving such a dispersity, the plating resistance and resin physical properties of the resist are excellent.

[0069] The content of the above component (F) is preferably 5 to 60% by weight based on the solid content of the chemically amplified positive photoresist composition.

[0070] <Alkali-soluble resin (G)> In order to improve the resin properties of the resist, the chemically amplified positive photoresist composition of the present invention preferably further contains an alkali-soluble resin (herein referred to as "component (G)"). Component (G) is preferably at least one resin selected from the group consisting of novolak resins, polyhydroxystyrene resins, acrylic resins, and polyvinyl resins.

[0071] The content of the component (G) is preferably 5 to 95 parts by weight, more preferably 10 to 90 parts by weight, relative to 100 parts by weight of the component (F). By making it 5 parts by weight or more, the resin properties of the resist can be improved, and by making it 95 parts by weight or less, there is a tendency that film loss during development can be prevented.

[0072] <Acid diffusion control agent (H)> The chemically amplified positive photoresist composition of the present invention preferably further contains an acid diffusion controller (H) (herein referred to as "component (H)") in order to improve the resist pattern shape, deposition stability, etc. Component (H) is preferably a nitrogen-containing compound, and may further contain an organic carboxylic acid or a phosphorus oxo acid or a derivative thereof, if necessary.

[0073] The chemically amplified positive photoresist composition of the present invention may further contain an adhesion promoter to improve adhesion to a substrate. The adhesion promoter used is preferably a functional silane coupling agent.

[0074] The chemically amplified positive photoresist composition of the present invention may further contain a surfactant in order to improve the coating properties, defoaming properties, leveling properties, and the like.

[0075] The chemically amplified positive photoresist composition of the present invention may further contain an acid, an acid anhydride, or a high-boiling point solvent in order to finely adjust the solubility in an alkaline developer.

[0076] In addition, the chemically amplified positive photoresist composition of the present invention does not basically require a sensitizer, but may contain a sensitizer as needed to supplement the sensitivity. As such a sensitizer, a conventionally known sensitizer may be used, specifically, the above-mentioned sensitizers may be mentioned.

[0077] The amount of these sensitizers used is 5 to 500 parts by weight, and preferably 10 to 300 parts by weight, per 100 parts by weight of the total weight of the onium salt represented by the above formula (1).

[0078] The chemically amplified positive photoresist composition of the present invention may contain an organic solvent to adjust the viscosity. Specific examples of the organic solvent include those mentioned above.

[0079] The amount of these organic solvents used is preferably in the range of a solids concentration of 30% by weight or more so that the thickness of a photoresist layer obtained by using the chemically amplified positive photoresist composition (e.g., by spin coating) is 5 μm or more.

[0080] The thick-film chemically amplified positive photoresist composition may be prepared, for example, by simply mixing and stirring the above-mentioned components in a conventional manner, and may be dispersed and mixed using a dispersing machine such as a dissolver, homogenizer, or triple roll mill, if necessary. After mixing, the components may be filtered using a mesh, membrane filter, or the like.

[0081] The chemically amplified positive photoresist composition of the present invention is suitable for forming a photoresist layer having a thickness of usually 5 to 150 μm, more preferably 10 to 120 μm, and even more preferably 10 to 100 μm, on a support. This photoresist laminate comprises a photoresist layer made of the chemically amplified positive photoresist composition of the present invention laminated on a support.

[0082] The support is not particularly limited, and can be a conventionally known one, for example, a substrate for electronic components, or a substrate on which a predetermined wiring pattern is formed. Examples of the substrate include metal substrates such as silicon, silicon nitride, titanium, tantalum, palladium, titanium tungsten, copper, chromium, iron, and aluminum, and glass substrates. In particular, the chemically amplified positive photoresist composition of the present invention can form a good resist pattern even on a copper substrate. Examples of materials for the wiring pattern include copper, solder, chromium, aluminum, nickel, and gold.

[0083] The photoresist laminate can be produced, for example, as follows. That is, a solution of the chemically amplified positive photoresist composition prepared as described above is applied onto a support, and the solvent is removed by heating to form a desired coating film. As a method for applying onto a support, methods such as spin coating, slit coating, roll coating, screen printing, and applicator methods can be adopted. The pre-bake conditions for the coating film of the composition of the present invention vary depending on the type of each component in the composition, the blending ratio, the coating film thickness, etc., but are usually 70 to 150°C, preferably 80 to 140°C, for about 2 to 60 minutes.

[0084] The thickness of the photoresist layer is usually in the range of 5 to 150 μm, preferably 10 to 120 μm, and more preferably 10 to 100 μm.

[0085] To form a resist pattern using the photoresist laminate thus obtained, the obtained photoresist layer may be selectively irradiated (exposed) to light or radiation, for example, ultraviolet light or visible light having a wavelength of 300 to 500 nm, through a mask having a predetermined pattern.

[0086] Here, "light" refers to any light that activates a photoacid generator to generate an acid, and includes ultraviolet light, visible light, and far ultraviolet light, and "radiation" refers to X-rays, electron beams, ion beams, etc. Examples of light or radiation sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, argon gas lasers, and LED lamps. The radiation dose varies depending on the type and amount of each component in the composition, the thickness of the coating film, etc., but for example, when an ultra-high-pressure mercury lamp is used, it is 50 to 10,000 mJ / cm. 2 It is.

[0087] After exposure, the photoresist layer is heated by a known method to promote diffusion of the acid and change the alkali solubility of the exposed portion of the photoresist layer. Next, the unnecessary portion is dissolved and removed using, for example, a specific alkaline aqueous solution as a developer to obtain a specific resist pattern.

[0088] The developing time varies depending on the type and blending ratio of each component of the composition and the dry film thickness of the composition, but is usually 1 to 30 minutes, and the developing method may be any of the puddle method, dipping method, paddle method, spray developing method, etc. After development, the film is washed with running water for 30 to 90 seconds and dried using an air gun or oven.

[0089] A conductor such as a metal can be embedded in the non-resist portion (the portion removed by the alkaline developer) of the resist pattern thus obtained by plating, for example, to form a connection terminal such as a metal post or a bump. The plating method is not particularly limited, and various conventionally known methods can be adopted. As the plating solution, a solder plating, copper plating, gold plating, or nickel plating solution is particularly preferably used. The remaining resist pattern is finally removed by using a stripping solution or the like according to a standard method.

[0090] The chemically amplified positive photoresist composition of the present invention can also be used as a dry film. This dry film is a film in which a protective film is formed on both sides of a layer made of the chemically amplified positive photoresist composition of the present invention. The thickness of the layer made of the chemically amplified positive photoresist composition is usually in the range of 10 to 150 μm, preferably 20 to 120 μm, and more preferably 20 to 80 μm. The protective film is not particularly limited, and a resin film that is conventionally used in dry films can be used. As an example, one of the protective films can be a polyethylene terephthalate film, and the other can be one selected from the group consisting of a polyethylene terephthalate film, a polypropylene film, and a polyethylene film.

[0091] The above-mentioned chemically amplified positive dry film can be produced, for example, as follows. That is, a solution of the chemically amplified positive photoresist composition prepared as described above is applied onto one of the protective films, and the solvent is removed by heating to form a desired coating film. The drying conditions vary depending on the types of components in the composition, the blending ratio, the coating film thickness, etc., but typically 60 to 100°C and about 5 to 20 minutes are sufficient.

[0092] To form a resist pattern using the chemically amplified dry film thus obtained, one protective film of the chemically amplified positive dry film is peeled off, and the exposed surface is laminated onto a support with the support facing the support described above to obtain a photoresist layer, and then the resist is dried by pre-baking, and the other protective film is peeled off.

[0093] In the photoresist layer thus obtained on the support, a resist pattern can be formed in the same manner as described above for the photoresist layer formed by directly coating on the support.

[0094] Next, the chemically amplified negative photoresist composition (3) contains an onium salt (A) of the present invention, which is a compound that generates an acid when exposed to light or radiation, functioning as an acid generator, and contains an alkali-soluble resin (I) having a phenolic hydroxyl group due to the action of the acid, and a crosslinking agent (J).

[0095] Alkali-soluble resin having phenolic hydroxyl group (I) As the "alkali-soluble resin having a phenolic hydroxyl group" in the present invention (hereinafter referred to as "phenolic resin (I)"), for example, novolac resin, polyhydroxystyrene, copolymer of polyhydroxystyrene, copolymer of hydroxystyrene and styrene, copolymer of hydroxystyrene, copolymer of styrene and (meth)acrylic acid derivative, phenol-xylylene glycol condensation resin, cresol-xylylene glycol condensation resin, phenol-dicyclopentadiene condensation resin, etc. are used. Among these, novolac resin, polyhydroxystyrene, copolymer of polyhydroxystyrene, copolymer of hydroxystyrene and styrene, copolymer of hydroxystyrene, copolymer of styrene and (meth)acrylic acid derivative, phenol-xylylene glycol condensation resin are preferred. These phenolic resins (I) may be used alone or in combination of two or more.

[0096] The phenolic resin (I) may contain a low molecular weight phenolic compound as a part of its components. Examples of the phenolic low molecular weight compound include 4,4'-dihydroxydiphenylmethane and 4,4'-dihydroxydiphenyl ether.

[0097] Crosslinker (J) The "crosslinking agent" in the present invention (hereinafter also referred to as "crosslinking agent (J)") is not particularly limited as long as it acts as a crosslinking component (curing component) that reacts with the phenolic resin (I). Examples of the crosslinking agent (J) include a compound having at least two or more alkyl-etherified amino groups in the molecule, a compound having at least two or more alkyl-etherified benzenes in the molecule as a skeleton, an oxirane ring-containing compound, a thiirane ring-containing compound, an oxetanyl group-containing compound, an isocyanate group-containing compound (including blocked compounds), and the like.

[0098] Among these crosslinking agents (J), compounds having at least two or more alkyl-etherified amino groups in the molecule and oxirane ring-containing compounds are preferred, and it is more preferred to use in combination a compound having at least two or more alkyl-etherified amino groups in the molecule and an oxirane ring-containing compound.

[0099] The amount of the crosslinking agent (J) in the present invention is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the phenolic resin (I). When the amount of the crosslinking agent (J) is 1 to 100 parts by weight, the curing reaction proceeds sufficiently, and the obtained cured product has a high resolution and a good pattern shape, and is excellent in heat resistance and electrical insulation, which is preferable. In addition, when a compound having an alkyl-etherified amino group and an oxirane ring-containing compound are used in combination, the content of the oxirane ring-containing compound is preferably 50% by weight or less, more preferably 5 to 40% by weight, and particularly preferably 5 to 30% by weight, when the total of the compound having an alkyl-etherified amino group and the oxirane ring-containing compound is taken as 100% by weight. In this case, the resulting cured film is preferable because it has excellent chemical resistance without impairing high resolution.

[0100] Crosslinked fine particles (K) The chemically amplified negative photoresist composition of the present invention may further contain crosslinked fine particles (hereinafter also referred to as "crosslinked fine particles (K)") in order to improve the durability and thermal shock resistance of the obtained cured product.

[0101] The average particle size of the crosslinked fine particles (K) is usually 30 to 500 nm, preferably 40 to 200 nm, and more preferably 50 to 120 nm. The method for controlling the particle size of the crosslinked microparticles (K) is not particularly limited. For example, when synthesizing the crosslinked microparticles by emulsion polymerization, the particle size can be controlled by controlling the number of micelles during emulsion polymerization by adjusting the amount of emulsifier used. The average particle size of the crosslinked fine particles (K) is a value measured by diluting a dispersion of the crosslinked fine particles in a conventional manner using a light scattering flow distribution measuring device or the like.

[0102] The amount of the crosslinked fine particles (K) is preferably 0.5 to 50 parts by weight, more preferably 1 to 30 parts by weight, based on 100 parts by weight of the phenolic resin (I). When the amount of the crosslinked fine particles (H) is 0.5 to 50 parts by weight, the compatibility or dispersibility with other components is excellent, and the thermal shock resistance and heat resistance of the resulting cured film can be improved.

[0103] Adhesion aid The chemically amplified negative photoresist composition of the present invention may contain an adhesion aid in order to improve adhesion to a substrate. Examples of the adhesion aid include functional silane coupling agents having a reactive substituent such as a carboxyl group, a methacryloyl group, an isocyanate group, or an epoxy group.

[0104] The amount of the adhesion assistant is preferably 0.2 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the phenolic resin (I). When the amount of the adhesion assistant is 0.2 to 10 parts by weight, excellent storage stability and good adhesion can be obtained, which is preferable.

[0105] solvent The chemically amplified negative photoresist composition of the present invention may contain a solvent in order to improve the handleability of the resin composition and to adjust the viscosity and storage stability. The solvent is not particularly limited, but specific examples include those mentioned above.

[0106] The chemically amplified negative photoresist composition of the present invention may contain a sensitizer, if necessary. As such a sensitizer, any of the conventionally known sensitizers may be used, and specific examples thereof include those mentioned above.

[0107] The amount of these sensitizers used is 5 to 500 parts by weight, and preferably 10 to 300 parts by weight, per 100 parts by weight of the total weight of the sulfonium salt represented by the above formula (1).

[0108] Other Additives In addition, the chemically amplified negative photoresist composition of the present invention may contain other additives, if necessary, to the extent that the properties of the present invention are not impaired. Examples of such additives include inorganic fillers, quenchers, leveling agents, surfactants, etc.

[0109] The method for preparing the chemically amplified negative photoresist composition of the present invention is not particularly limited, and it can be prepared by a known method. It can also be prepared by stirring a sample bottle containing each component and completely stoppered on a wave rotor.

[0110] The cured product in the present invention is characterized by being obtained by curing the above-mentioned chemically amplified negative photoresist composition. The above-mentioned chemically amplified negative photoresist composition according to the present invention has a high film retention rate and excellent resolution, and the cured product thereof has excellent electrical insulation properties, thermal shock resistance, etc., and therefore the cured product thereof can be suitably used as a surface protective film, a planarizing film, an interlayer insulating film material, etc. for electronic components such as semiconductor elements and semiconductor packages.

[0111] To form the cured product of the present invention, the above-mentioned chemically amplified negative photoresist composition according to the present invention is first applied to a support (such as a resin-coated copper foil, a copper-clad laminate, or a silicon wafer or alumina substrate with a metal sputtered film), and then dried to volatilize the solvent and other components to form a coating film. Thereafter, the coating is exposed through a desired mask pattern and heat-treated (hereinafter, this heat treatment is referred to as "PEB") to promote the reaction between the phenolic resin (F) and the crosslinking agent (G). The coating is then developed with an alkaline developer to dissolve and remove the unexposed areas, thereby obtaining a desired pattern. Furthermore, a heat treatment is performed to develop insulating film properties, thereby obtaining a cured film.

[0112] Examples of methods that can be used for applying the resin composition to a support include a dipping method, a spraying method, a bar coating method, a roll coating method, a spin coating method, etc. The thickness of the applied film can be appropriately controlled by adjusting the application means, the solids concentration of the composition solution, and the viscosity. Examples of radiation used for exposure include ultraviolet rays from a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a g-line stepper, an h-line stepper, an i-line stepper, a gh-line stepper, a ghi-line stepper, an electron beam, a laser beam, etc. The exposure dose is appropriately selected depending on the light source used, the resin film thickness, etc., but for example, in the case of ultraviolet irradiation from a high pressure mercury lamp, the dose is about 100 to 50,000 J / m2 for a resin film thickness of 1 to 50 μm.

[0113] After the exposure, the above-mentioned PEB treatment is carried out in order to promote the curing reaction of the phenolic resin (F) and the crosslinking agent (G) by the generated acid. The PEB conditions vary depending on the blending amount of the resin composition and the thickness of the film used, but are usually 70 to 150°C, preferably 80 to 120°C, and about 1 to 60 minutes. Thereafter, the film is developed with an alkaline developer to dissolve and remove the unexposed areas to form a desired pattern. Examples of the development method in this case include shower development, spray development, immersion development, and paddle development. The development conditions are usually 20 to 40°C and about 1 to 10 minutes.

[0114] Furthermore, in order to fully express the properties as an insulating film after development, the composition can be sufficiently cured by performing a heat treatment. Although such curing conditions are not particularly limited, the composition can be cured by heating at a temperature of 50 to 250 ° C for about 30 minutes to 10 hours depending on the application of the cured product. In addition, the composition can be heated in two stages to fully advance the curing or prevent the deformation of the obtained pattern shape. For example, in the first stage, the composition can be heated at a temperature of 50 to 120 ° C for about 5 minutes to 2 hours, and then heated at a temperature of 80 to 250 ° C for about 10 minutes to 10 hours to be cured. If the curing conditions are as described above, a general oven, an infrared furnace, etc. can be used as the heating equipment. EXAMPLES

[0115] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In each example, "parts" refers to parts by weight.

[0116] Preparation examples of anions (B1) to (B6) and (B'1)

[0117] Anion (B1) Production Example While cooling, 4.44 g of potassium fluoride (KF) was slowly added to 50.0 g of dimethoxyethane, and then 32.5 g of tris(pentafluoroethyl)difluorophosphorane was added while stirring. The mixture was slowly added while cooling so that the temperature remained below 30°C, and the reaction was continued to produce potassium salt of tris(heptafluoroethyl)trifluorophosphonate (K + [(C2F5)3(F)3P] - ) solution was obtained. As a result of F-NMR, the proportion of the facial isomer among the two isomers was 0.0% by weight.

[0118] Anion (B2) Production Example While cooling, 4.44 g of potassium fluoride (KF) was slowly added to 50.0 g of dimethoxyethane, and then 43.9 g of tris(heptafluoropropyl)difluorophosphorane was added while stirring. The mixture was slowly added while cooling so that the temperature remained below 30°C, and the reaction was allowed to proceed, producing potassium tris(heptafluoropropyl)trifluorophosphonate (K + [(C3F7)3(F)3P] - ) solution was obtained. As a result of F-NMR, the proportion of the facial isomer among the two isomers was 0.0% by weight.

[0119] Anion (B3) Production Example 7.04 g of a 40% aqueous solution of hydrofluoric acid was diluted with 19.0 g of ion-exchanged water and cooled to below 5°C in advance, after which 60.0 g of tris(pentafluoroethyl)difluorophosphorane was slowly added while stirring. The mixture was slowly added while cooling so that the temperature remained below 10°C and allowed to react. Thereafter, 7.90 g of potassium hydroxide was dissolved in 30 g of ion-exchanged water in advance and then added to obtain the potassium salt of tris(heptafluoropropyl)trifluorophosphonate (K + [(C2F5)3(F)3P] - As a result of F-NMR, the ratio of the facial isomer to the two isomers was 0.1% by weight.

[0120] Anion (B4) Production Example 5.65 g of 40% hydrofluoric acid aqueous solution was diluted with 6.73 g of ion-exchanged water and cooled to below 5°C in advance, and then 47.8 g of tris(pentafluoroethyl)difluorophosphorane was slowly added while stirring. The mixture was slowly added while cooling so that the temperature remained below 10°C and reacted. Thereafter, 6.29 g of potassium hydroxide was dissolved in 30 g of ion-exchanged water in advance and then added to obtain the potassium salt of tris(heptafluoropropyl)trifluorophosphonate (K + [(C2F5)3(F)3P] - As a result of F-NMR, the ratio of the facial isomer to the two isomers was 5.0% by weight.

[0121] Anion (B5) Production Example While cooling, 1.66 g of hydrogen fluoride (HF) was slowly added to 11.0 g of diethyl ether, and then 33.6 g of tris(pentafluoroethyl)difluorophosphorane was slowly added while stirring. The mixture was slowly added while cooling so that the temperature remained below 5°C, and the reaction was allowed to proceed. After that, 4.42 g of potassium hydroxide was added to obtain the potassium salt of tris(heptafluoropropyl)trifluorophosphonate (K + [(C2F5)3(F)3P] - ) solution was obtained. As a result of F-NMR, the ratio of the facial isomer to the two isomers was found to be 14.6% by weight.

[0122] Anion (B6) Production Example 7.51 g of 40% hydrofluoric acid aqueous solution was diluted with 10.0 g of ion-exchanged water and cooled to below 5°C in advance, and then 63.6 g of tris(pentafluorophenyl)difluorophosphorane was slowly added while stirring. The mixture was slowly added while cooling so that the temperature remained below 10°C, and the reaction was allowed to proceed. After that, 8.36 g of potassium hydroxide was dissolved in 30 g of ion-exchanged water in advance and then added to obtain the potassium salt of tris(pentafluorophenyl)trifluorophosphonate (K + [(C6F5)3(F)3P] - ) solution was obtained. As a result of F-NMR, the ratio of the facial isomer to the two isomers was 5.0% by weight.

[0123] Anion (B'1) Production Example While cooling, 1.64 g of hydrogen fluoride (HF) was slowly added to 6.00 g of methanol, and then 32.5 g of tris(pentafluoroethyl)difluorophosphorane was slowly added while stirring. The mixture was slowly added while cooling so that the temperature remained below 5°C, and the reaction was allowed to proceed. After that, 4.28 g of potassium hydroxide was added to obtain the potassium salt of tris(heptafluoropropyl)trifluorophosphonate (K + [(C2F5)3(F)3P] - As a result of F-NMR, the ratio of the facial isomer to the two isomers was found to be 18.4% by weight.

[0124] Example of Onium Salt (A1-1) Preparation of 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight) After uniformly mixing 12.12g of diphenyl sulfoxide, 9.3g of diphenyl sulfide, and 43.0g of methanesulfonic acid, 7.9g of acetic anhydride was added dropwise. After reacting at 50°C for 5 hours, it was cooled to room temperature. To this reaction solution, 124.5g of anion (B1) adjusted to a 20% aqueous solution or solvent-substituted was added dropwise and stirred for 2 hours. The precipitated oily matter was extracted with 120g of ethyl acetate, and after separating the water layer, the organic layer was washed three times. The solvent was removed from this organic layer, 50g of toluene was added and dissolved, and then 270g of hexane was added and mixed, and the mixture was left for 1 hour to separate into two layers. The upper layer was removed, and 150g of hexane was added to the remaining lower layer, and when it was thoroughly stirred, crystals were precipitated. The crystals were filtered and dried under reduced pressure to obtain 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A1-1). The chemical formula is as shown below (a1).

[0125] [ka]

[0126] Examples of Onium Salts (A1-2) to (A1-6) and Comparative Example (A'1-1)

[0127] Instead of the anion (B1) in the manufacturing example of (A1-1), the anions (B2) to (B6) and (B'1) were used to obtain onium salts (A1-2) to (A1-6) and (A'1-1). Note that the amount of the 20% aqueous solution of anion (B2) was 167 g. The names of the synthesized compounds are as follows: (A1-2): 4-(phenylthio)phenyldiphenylsulfonium tris(heptafluoropropyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A1-3): 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.1% by weight) (A1-4): 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A1-5): 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 14.6% by weight) (A1-6): 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluorophenyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A'1-1): 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 18.4% by weight)

[0128] The chemical formula is (A1-2) is (a2), (A1-3) to (A1-5) and (A'1-1) are (a1), and (A1-6) is (a3).

[0129] [ka]

[0130] [ka]

[0131] Example of onium salt (A2-1) Preparation of (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight) 20g of 4-methyliodobenzene was added, and 50g of acetic acid and 10g of sulfuric acid were added and dissolved. While cooling in an ice-water bath, 10g of potassium persulfate was added little by little at 15℃ or less. The reaction was carried out at 20℃ for 4 hours, and 24.4g of cumene was added dropwise so that the temperature did not exceed 20℃. The reaction was then carried out at room temperature for 20 hours. The reaction liquid was poured into 50 parts of an aqueous solution containing an equimolar amount of anion (B1) and stirred for another 3 hours. 500 parts of dichloromethane was added thereto. After leaving it to stand, the aqueous layer was removed by separation, and the organic layer was washed five times with 100 parts of water. Dichloromethane was concentrated and recrystallized with cyclohexane to obtain (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight). The chemical formula is as follows: (a4).

[0132] [ka]

[0133] Examples of Onium Salts (A2-2) to (A2-6) and Comparative Example (A'2-1)

[0134] Instead of the anion (B1) in the manufacturing example of (A2-1), the anions (B2) to (B6) and (B'1) were used to obtain onium salts (A2-2) to (A2-6) and (A'2-1). Note that the amount of the 20% aqueous solution of anion (B2) was 167 g. The names of the synthesized compounds are as follows: (A2-2): (4-isopropylphenyl)tolyliodonium tris(heptafluoropropyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A2-3): (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.1% by weight) (A2-4): (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A2-5): (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 14.6% by weight) (A2-6): (4-isopropylphenyl)tolyliodonium tris(pentafluorophenyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A'2-1): (4-isopropylphenyl)tolyliodonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 18.4% by weight)

[0135] The chemical formula for (A2-2) is (a5), for (A2-3) to (A2-5) and (A'2-1) are (a4), and for (A2-6) is (a6).

[0136] [ka]

[0137] [ka]

[0138] Example of onium salt (A3-1) Preparation of [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight) 11 g of 4-[(phenyl)sulfinyl]biphenyl, 12 g of 4-(phenylthio)biphenyl, 22 g of acetic anhydride, and 16 parts of methanesulfonic acid were mixed uniformly and reacted at 65°C for 3 hours. The reaction solution was cooled to room temperature, poured into 100 mL of ion-exchanged water, extracted with 100 g of dichloromethane, and washed with water until the pH of the aqueous layer became neutral. The dichloromethane layer was transferred to a rotary evaporator and the solvent was distilled off to obtain a brown solid. This was washed with ethyl acetate / hexane, and the organic solvent was concentrated to obtain an intermediate. 6.2g of this intermediate was dissolved in 60mL of dichloromethane, mixed with 70g of an aqueous solution containing anion (B1) at room temperature, stirred for 3 hours, and the dichloromethane layer was washed 5 times with water by a separation operation, then transferred to a rotary evaporator to remove the solvent, yielding [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight). The chemical formula is as follows: (a7).

[0139] [ka]

[0140] Examples of Onium Salts (A3-2) to (A3-6) and Comparative Example (A'3-1)

[0141] Instead of the anion (B1) in the manufacturing example of (A3-1), the anions (B2) to (B6) and (B'1) were used to obtain onium salts (A3-2) to (A3-6) and (A'3-1). Note that the amount of the 20% aqueous solution of anion (B2) was 167 g. The names of the synthesized compounds are as follows: (A3-2): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(heptafluoropropyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A3-3): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.1% by weight) (A3-4): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A3-5): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 14.6% by weight) (A3-6): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluorophenyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A'3-1): [4-(4-biphenylthio)phenyl]-4-biphenylphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 18.4% by weight)

[0142] The chemical formula for (A3-2) is (a8), for (A3-3) to (A3-5) and (A'3-1) it is (a7), and for (A3-6) it is (a9).

[0143] [ka]

[0144] [ka]

[0145] Example of onium salt (A4-1) Preparation of [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight) 89 parts of a dichloromethane solution containing 32 parts of (4-phenylthio)phenyldiphenylsulfonium trifluoromethanesulfonate was added dropwise to a suspension of 36 parts of aluminum chloride, 12 parts of acetyl chloride, and 200 parts of dichloromethane under stirring and cooling conditions at 10°C or less. After the addition, the mixture was stirred at room temperature for 2 hours, and then 300 parts of cold water was added. The upper layer was removed, and the dichloromethane layer was washed with ion-exchanged water until the pH became neutral. Next, 70 g of an aqueous solution containing anion (B1) was mixed at room temperature and stirred for 3 hours. The dichloromethane layer was washed five times with water by a separation operation, and then transferred to a rotary evaporator to distill off the solvent, thereby obtaining [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight). The chemical formula is shown below in formula (a10).

[0146] [ka]

[0147] Examples of Onium Salts (A4-2) to (A4-6) and Comparative Example (A'4-1)

[0148] Instead of the anion (B1) in the manufacturing example of (A4-1), the anions (B2) to (B6) and (B'1) were used to obtain onium salts (A4-2) to (A4-6) and (A'4-1). Note that the amount of the 20% aqueous solution of anion (B2) was 167 g. The names of the synthesized compounds are as follows: (A4-2): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(heptafluoropropyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A4-3): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.1% by weight) (A4-4): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A4-5): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 14.6% by weight) (A4-6): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluorophenyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A'4-1): [4-(4-acetylphenylthio)]phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 18.4% by weight)

[0149] The chemical formula for (A4-2) is (a11), for (A4-3) to (A4-5) and (A'4-1) it is (a10), and for (A4-6) it is (a12).

[0150] [ka]

[0151] [ka]

[0152] Example of onium salt (A5-1) Preparation of fluorene-based sulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0 wt%) 1.0 part of 2-[(phenyl)sulfinyl]-9,9-dimethylfluorene, 1.1 parts of 2-(phenylthio)-9,9-dimethylfluorene, 2.0 parts of acetic anhydride, and 1.6 parts of methanesulfonic acid were charged and stirred at 65°C for 3 hours. The reaction solution was cooled to room temperature, poured into 5.0 parts of ion-exchanged water, extracted with 5.0 parts of dichloromethane, and washed with ion-exchanged water until the pH of the aqueous layer became neutral. Next, 70 g of an aqueous solution containing anion (B1) was mixed with the dichloromethane layer under stirring at room temperature, and the mixture was stirred for 3 hours. The dichloromethane layer was washed five times with water by a separation operation, and then transferred to a rotary evaporator to distill off the solvent, thereby obtaining [4-(4-acetylphenylthio)]phenyldiphenylsulfonium·tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.0% by weight). The chemical formula is as follows: Formula (a13).

[0153] [ka]

[0154] Examples of Onium Salts (A5-2) to (A5-6) and Comparative Example (A'5-1)

[0155] Instead of the anion (B1) in the manufacturing example of (A5-1), the anions (B2) to (B6) and (B'1) were used to obtain onium salts (A5-2) to (A5-6) and (A'5-1). Note that the amount of the 20% aqueous solution of anion (B2) was 167 g. The synthesized compounds are as follows: (A5-2): Fluorene-based sulfonium tris(heptafluoropropyl)trifluorophosphonate (facial form of anion: 0.0% by weight) (A5-3): Fluorene-based sulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 0.1% by weight) (A5-4): Fluorene-based sulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A5-5): Fluorene-based sulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 14.6% by weight) (A5-6): Fluorene-based sulfonium tris(pentafluorophenyl)trifluorophosphonate (facial form of anion: 5.0% by weight) (A'5-1): Fluorene-based sulfonium tris(pentafluoroethyl)trifluorophosphonate (facial form of anion: 18.4% by weight)

[0156] The chemical formula for (A5-2) is (a14), for (A5-3) to (A5-5) and (A'5-1) it is (a13), and for (A5-6) it is (a15).

[0157] [ka]

[0158] [ka]

[0159] [Evaluation of Chemically Amplified Positive Photoresist Compositions] <Preparation of evaluation samples> As shown in Table 1, 1 part by weight of the onium salts (A1-1) to (A1-6), (A2-1) to (A2-6), (A3-1) to (A3-6), (A4-1) to (A4-6), and (A5-1) to (A-6) of the present invention as a photoacid generator, 40 parts by weight of a resin represented by the following chemical formula (Resin-1) as a resin component (F), and 60 parts by weight of a novolak resin obtained by addition condensation of m-cresol and p-cresol in the presence of formaldehyde and an acid catalyst as a resin component (G) were uniformly dissolved in a solvent (propylene glycol monomethyl ether acetate) and filtered through a membrane filter with a pore size of 1 μm to prepare chemically amplified positive photoresist compositions (Examples P1 to P30) with a solid content concentration of 40% by weight. Comparative examples were also carried out in the same manner using the blending amounts shown in Table 1 to prepare chemically amplified positive photoresist compositions (Comparative Examples P'1 to P'5).

[0160] [Table 1]

[0161] [ka]

[0162] <Sensitivity evaluation> The positive resist compositions prepared in the above Examples P1 to P30 and Comparative Examples P'1 to P'5 were spin-coated on a silicon wafer substrate, and then dried to obtain a photoresist layer having a thickness of about 20 μm. This resist layer was pre-baked on a hot plate at 130° C. for 6 minutes. After pre-baking, a pattern exposure (i-line) was performed using a TME-150RSC (manufactured by Topcon Corporation), and post-exposure baking (PEB) was performed on a hot plate at 75° C. for 5 minutes. Thereafter, a development process was performed for 5 minutes by immersion using a 2.38 wt % tetramethylammonium hydroxide aqueous solution, followed by washing with running water and blowing with nitrogen to obtain a 10 μm line and space (L&S) pattern. Furthermore, the minimum exposure dose below which no residue of this pattern was observed, that is, the minimum required exposure dose (corresponding to sensitivity) required to form a resist pattern, was measured.

[0163] <Pattern shape evaluation> The dimension of the bottom side La and the dimension of the top side Lb of the cross section of the 10 μm L&S pattern formed on the silicon wafer substrate by the above operation were measured using a scanning electron microscope, and the pattern shape was judged according to the following criteria. The results are shown in Table 2. ◎: 0.90≦Lb / La≦1 ○:0.85≦Lb / La<0.90 ×:Lb / La<0.85

[0164] [Table 2]

[0165] As shown in Table 2, the chemically amplified positive photoresist compositions of Examples P1 to P30 have a lower required minimum exposure dose than the comparative examples P'1 to P'5. In other words, the photoacid generators of the present invention are more sensitive than the comparative photoacid generators and produce superior pattern shapes.

[0166] [Evaluation of Chemically Amplified Negative Photoresist Compositions] <Preparation of evaluation samples> As shown in Table 3, the following compounds were used: 1 part by weight of the onium salts (A1-1) to (A1-6), (A2-1) to (A2-6), (A3-1) to (A3-6), (A4-1) to (A4-6), and (A5-1) to (A-6) of the present invention as a photoacid generator; 100 parts by weight of a copolymer (Mw=10,000) consisting of p-hydroxystyrene / styrene=80 / 20 (molar ratio) as component (I) which is a phenol resin; 2 parts by weight of hexamethoxymethylmelamine (manufactured by Sanwa Chemical Co., Ltd., product name "Nikarac MW-390") as component (J) which is a crosslinking agent; 0 parts by weight, 10 parts by weight of a copolymer (average particle size = 65 nm, Tg = -38 ° C) consisting of butadiene / acrylonitrile / hydroxybutyl methacrylate / methacrylic acid / divinylbenzene = 64 / 20 / 8 / 6 / 2 (weight %) as a component (K) which is a crosslinked fine particle, 5 parts by weight of γ-glycidoxypropyltrimethoxysilane (manufactured by Chisso Corporation, product name "S510") as an adhesion promoter were uniformly dissolved in 150 parts by weight of a solvent (ethyl lactate) to prepare chemically amplified negative photoresist compositions (Examples N1 to N30) of the present invention. In addition, the comparative examples were also similarly carried out with the blending amounts shown in Table 3 to prepare chemically amplified negative photoresist compositions (Comparative Examples N'1 to N'5).

[0167] [Table 3]

[0168] <Sensitivity evaluation> Each composition was spin-coated on a silicon wafer substrate, and then heated and dried at 110°C for 3 minutes using a hot plate to obtain a resin coating film having a thickness of about 20 μm. Then, pattern exposure (i-line) was performed using TME-150RSC (manufactured by Topcon Corporation), and post-exposure baking (PEB) was performed at 110°C for 3 minutes using a hot plate. Then, development was performed for 2 minutes by immersion using a 2.38 wt% tetramethylammonium hydroxide aqueous solution, washed with running water, and blown with nitrogen to obtain a 10 μm line and space pattern. Furthermore, the minimum required exposure amount (corresponding to sensitivity) required to form a pattern with a residual film ratio of 95% or more, which indicates the ratio of the residual film before and after development, was measured.

[0169] <Pattern shape evaluation> The dimension of the bottom side La and the dimension of the top side Lb of the cross section of the 20 μm L&S pattern formed on the silicon wafer substrate by the above operation were measured using a scanning electron microscope, and the pattern shape was judged according to the following criteria. The results are shown in Table 6. ◎: 0.90≦La / Lb≦1 ○:0.85≦La / Lb<0.90 ×: La / Lb<0.85

[0170] [Table 4]

[0171] As shown in Table 4, the chemically amplified positive photoresist compositions of Examples N1 to N30 have a lower required minimum exposure dose than the comparative examples N'1 to N'5. In other words, the photoacid generators of the present invention have higher sensitivity and superior pattern shape than the comparative photoacid generators. [Industrial Applicability]

[0172] The chemically amplified positive photoresist composition and the chemically amplified negative photoresist composition using the acid generator containing the onium salt of the present invention can provide a highly sensitive resist (pattern formation is possible with a lower exposure dose than conventional resists). Furthermore, the chemically amplified positive photoresist composition and the chemically amplified negative photoresist composition of the present invention can be used to obtain a good resist pattern shape.

Claims

1. An onium salt represented by the general formula (1), in which the proportion of the facial isomer among two types of isomers, facial and meridional, of the anion structure is 15.0% by weight or less. [(R ２ ) ｎ＋１ -E] ＋ [(R １ ) ３ (F) ３ P] － (1) [In formula (1), R １ is a perfluoroalkyl group or a phenyl group substituted with a fluorine atom; E is I or S; R ２ is an organic group bonded to E, the organic group being an aryl group having 6 to 18 carbon atoms which may have a substituent, the substituent being an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an arylthio group. ２ The number of R is n+1, and (n+1) R ２ may be the same or different, and two or more R ２ are mutually directly or -O-, -S-, -SO-, -SO ２ A ring structure containing the element E may be formed via -, -NH-, -CO-, -COO-, -CONH-, an alkylene group or a phenylene group.]

2. 2. The onium salt according to claim 1, wherein the proportion of facial isomers is 0.1 to 15.0% by weight.

3. A photoacid generator comprising the onium salt according to claim 1 or 2.

4. A chemically amplified resist composition comprising the onium salt according to claim 1 or 2.

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