Method for producing sulfonium salt

Abstract

To provide a method for producing a sulfonium salt having a triaryl sulfonium cation into which a fluorine atom or a fluoroalkyl group and an iodine atom are introduced, the method being capable of producing the sulfonium salt with high purity and high efficiency.SOLUTION: Provided is a method for obtaining a sulfonium salt represented by the following formula, by reacting a specific sulfoxide compound and an iodobenzene derivative in the presence of a sulfonic acid compound and phosphorus pentoxide, and in the substantial absence of any chlorinated solvent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel method for efficiently producing a triarylsulfonium salt having a fluorine atom or a fluoroalkyl group and an iodine atom introduced therein with high purity while suppressing the production of by-products. [Background technology]

[0002] The increase in capacity and miniaturization of electronic devices is achieved by increasing the density and integration of semiconductor integrated circuits. One method for increasing the density and integration of semiconductor integrated circuits is to form fine patterns on semiconductors using photolithography technology.

[0003] In photolithography, a chemically amplified resist containing a photoacid generator and an acid-reactive compound is subjected to exposure and development processes to form a pattern. By shortening the wavelength of the light used in the exposure process, the pattern can be made finer.

[0004] As photoacid generators having high sensitivity to light of short wavelengths, sulfonium salts into which a fluorine atom or a fluoroalkyl group has been introduced are known.

[0005] Patent Document 1 describes the production of bis[3,5-bis(trifluoromethyl)phenyl]phenylsulfonium trifluoromethanesulfonate, which is an example of the sulfonium salt, by reacting bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide with benzene in the presence of trifluoromethanesulfonic anhydride and dichloromethane.

[0006] However, the method of Patent Document 1 has a problem in that the reactivity of the sulfonium reaction is low and side reactions are likely to occur, making the purification process complicated and resulting in a low yield of the target compound.

[0007] Patent Document 2 describes that when the reaction of bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide with benzene is carried out in the presence of trifluoromethanesulfonic anhydride or diphosphorus pentoxide, a chlorine-based solvent such as dichloromethane, and trifluoromethanesulfonic acid, side reactions are suppressed and the reactivity of the sulfonation reaction is improved, making it possible to produce bis[3,5-bis(trifluoromethyl)phenyl]phenylsulfonium trifluoromethanesulfonate in high yield and high purity. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2017-008014 A [Patent Document 2] JP 2022-126072 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the case of reacting a sulfoxide having a fluorine atom or a fluoroalkyl group, such as bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide, with an aromatic compound having an iodine atom, such as iodobenzene, instead of benzene, in the production method of the above-mentioned patent document, the progress of the sulfonation reaction is significantly reduced and the reaction of producing by-products proceeds, so that the product contains a large amount of by-products and the yield of the sulfonium salt having a fluorine atom or a fluoroalkyl group and a triarylsulfonium cation into which an iodine atom has been introduced is significantly reduced.

[0010] Therefore, an object of the present invention is to provide a method for efficiently producing a sulfonium salt having a fluorine atom or a fluoroalkyl group and a triarylsulfonium cation having an iodine atom introduced therein, with high purity while suppressing the production of by-products. [Means for solving the problem]

[0011] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they have found that when a sulfoxide having a fluorine atom or a fluoroalkyl group is reacted with an aromatic compound having an iodine atom in the presence of a specific amount of a sulfonic acid compound and diphosphorus pentoxide, and in the substantial absence of a chlorine-based solvent, a sulfonium salt having a fluorine atom or a fluoroalkyl group and a triarylsulfonium cation having an iodine atom introduced therein can be produced with high purity and high yield. The present invention was completed based on these findings.

[0012] That is, the present invention relates to a compound represented by the following formula (1): [ka] (In the formula, R f 1 , R f 2 are the same or different and each represents a fluorine atom or a fluoroalkyl group; n1 and n2 are the same or different and each represents an integer of 1 or more. and a compound represented by the following formula (2): [ka] (In the formula, R 1 represents an iodine atom, a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group; and n3 represents an integer of 0 or more. in the presence of 0.3 to 10 mol of diphosphorus pentoxide per mol of compound (1) and in the substantial absence of a chlorine-based solvent, to obtain a compound represented by the following formula (3): [ka] (In the formula, X - R represents the anion derived from the sulfonic acid. f 1 , R f 2 , R 1 , n1, n2, and n3 are the same as above. The present invention provides a method for producing a sulfonium salt, which produces a sulfonium salt (3) represented by the following formula:

[0013] The present invention also provides the method for producing the sulfonium salt, wherein the sulfonic acid is a fluorinated alkylsulfonic acid.

[0014] The present invention also provides a process for the preparation of said sulfonium salt, which reaction gives a product having the following composition: <Product composition> Content of the compound represented by formula (1): 15% by weight or less Content of the sulfonium salt represented by formula (3): 70% by weight or more Content of the sulfonium salt represented by the following formula (3b): 15% by weight or less [ka] (In the formula, R f 1 , R f 2 , n1, n2, X - is the same as above)

[0015] The present invention also provides a method for producing the sulfonium salt, wherein the reaction is carried out substantially in the absence of a solvent. Effect of the Invention

[0016] The sulfonation reaction of the above compounds (1) and (2) to produce a sulfonium salt (3) having a triarylsulfonium cation with a fluorine atom or a fluoroalkyl group and an iodine atom introduced therein is difficult to proceed because compound (2) has an iodine atom, and side reactions tend to proceed. In addition, the main product, the sulfonium salt (3), and the by-products are compounds with similar properties, making separation and purification difficult.

[0017] However, in the production method according to the present invention, the sulfonium formation reaction is carried out in the presence of specific amounts of a sulfonic acid compound and diphosphorus pentoxide, and in the substantial absence of chlorine-based solvents, so that the reaction proceeds more quickly and the side reactions are suppressed, and the sulfonium salt (3), which is the main product, can be produced efficiently and with high purity.

[0018] In addition, the main product, sulfonium salt (3), is R 1 In the case of a compound that does not have a group, or 1 When the group has an iodine atom, it is possible to selectively produce, among the sulfonium salts (3), a sulfonium salt in which the iodine atom is bonded to the para-position relative to the sulfur atom, and it is possible to suppress the production of positional isomers.

[0019] The main product, sulfonium salt (3), is R 1 In the case of a compound having a group other than an iodine atom (a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group) as a group, among the above sulfonium salts (3), R 1 It is possible to selectively produce a sulfonium salt in which the group is bonded to the para-position relative to the sulfur atom, and it is possible to suppress the formation of positional isomers.

[0020] The sulfonium salt (3) thus obtained has excellent sensitivity to light with ultrashort wavelengths, such as EUV (extreme ultraviolet), EB (electron beam), and X-rays, and is easily decomposed to produce an acid (H + X - ) can be generated. Therefore, if the sulfonium salt (3) is added to a resist used in photolithography, fine patterns can be formed with high precision using light with an ultrashort wavelength, and further increases in capacity and further miniaturization of electronic devices can be realized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] [Method of producing sulfonium salt] The method for producing a sulfonium salt of the present invention is a method for producing a sulfonium salt represented by the following formula (1): [ka] (In the formula, R f 1 , R f 2 are the same or different and each represents a fluorine atom or a fluoroalkyl group; n1 and n2 are the same or different and each represents an integer of 1 or more. (hereinafter, may be referred to as "sulfoxide (1)") and a compound represented by the following formula (2) [ka] (In the formula, R 1 represents an iodine atom, a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group; and n3 represents an integer of 0 or more. (hereinafter, sometimes referred to as "aryl iodide (2)") is subjected to a sulfonation reaction in the presence of 2 moles or more of a sulfonic acid compound relative to 1 mole of the compound represented by the formula (1) and 0.3 to 5 moles of diphosphorus pentoxide relative to 1 mole of the compound represented by the formula (1), in the substantial absence of a chlorine-based solvent, to obtain a compound represented by the following formula (3): [ka] (In the formula, X - R represents the anion derived from the sulfonic acid compound. f 1 , R f 2 , R 1 , n1, n2, and n3 are the same as above. This is a method for obtaining a sulfonium salt represented by the following formula (hereinafter, sometimes referred to as “triarylsulfonium salt (3)”).

[0022] In addition, the symbols A, B, and C attached to the benzene rings in the above formula are symbols attached to distinguish the benzene rings in the formula. Hereinafter, the benzene ring attached with A will be referred to as "benzene ring A," the benzene ring attached with B will be referred to as "benzene ring B," and the benzene ring attached with C will be referred to as "benzene ring C."

[0023] (Sulfoxide (1)) Sulfoxide (1) is a compound represented by the above formula (1), f 1 , R f 2 are the same or different and each represents a fluorine atom or a fluoroalkyl group. n1 and n2 are the same or different and each represents an integer of 1 or more.

[0024] The fluoroalkyl group is an alkyl group in which at least one hydrogen atom has been substituted with a fluorine atom.

[0025] The alkyl group is, for example, an alkyl group having 1 to 5 carbon atoms, and examples thereof include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, and a pentyl group.

[0026] As the fluoroalkyl group, fluoro C 1-5 Alkyl groups are preferred, and fluoro C 1-3 Alkyl groups are more preferred, and fluoro C 1-2 Alkyl groups are particularly preferred.

[0027] The fluoroalkyl group may be a group in which all hydrogen atoms of an alkyl group are substituted with fluorine atoms, that is, a perfluoroalkyl group (e.g., perfluoro C 1-5 alkyl group) is preferred.

[0028] The n1 is R bonded to the benzene ring A. f 1 It is the number of groups and represents an integer of 1 or more (for example, an integer of 1 to 5). Among them, the above n1 is particularly preferably 1 or 2, and especially preferably 1, from the viewpoint of improving sensitivity to light rays with ultrashort wavelengths.

[0029] The n2 is R bonded to the benzene ring B. f 2It is the number of groups and represents an integer of 1 or more (for example, an integer of 1 to 5). Among them, the above n2 is particularly preferably 1 or 2, and especially preferably 1, from the viewpoint of improving sensitivity to light rays with ultrashort wavelengths.

[0030] In addition to the above groups, other substituents may be bonded to the benzene ring A and the benzene ring B. Examples of the other substituents include an alkyl group and an iodine atom.

[0031] (Aryl iodide (2)) The aryl iodide (2) is a compound represented by the above formula (2), 1 represents an iodine atom, a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group, and n3 represents an integer of 0 or more.

[0032] The alkyl group is, for example, an alkyl group having 1 to 5 carbon atoms, and examples of such linear or branched alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, and a pentyl group.

[0033] The alkyl group may be C 1-5 Alkyl groups are preferred, C 1-3 Alkyl groups are more preferred, C 1-2 Alkyl groups are particularly preferred.

[0034] The hydroxyalkyl group is a group represented by the formula [-R-OH]. The R represents a group obtained by removing one hydrogen atom from the structural formula of an alkyl group. 1 Examples of the alkyl group are the same as those of the alkyl group in the above.

[0035] The hydroxyalkyl group may be hydroxyC 1-5 Alkyl groups are preferred, hydroxy C 1-3 Alkyl groups are more preferred, and hydroxy C 1-2 Alkyl groups are particularly preferred.

[0036] The alkoxy group is a group represented by the formula [-OR']. The R' represents an alkyl group, and the R 1 Examples of the alkyl group are the same as those of the alkyl group in the above.

[0037] The alkoxy group is, for example, 1-5 Alkoxy groups are preferred, C 1-3 Alkoxy groups are more preferred, C 1-2 Alkoxy groups are particularly preferred.

[0038] The n3 is R bonded to the benzene ring C. 1 n3 is the number of R groups and represents an integer of 0 or more (for example, an integer of 0 to 5). From the viewpoint of improving sensitivity to light rays with ultrashort wavelengths, n3 is particularly preferably an integer of 0 to 2, and particularly preferably 0 or 1. When n3 is an integer of 2 or more, two or more R 1 may be the same or different.

[0039] The number of iodine atoms bonded to the benzene ring C is at least 1, and from the viewpoint of improving sensitivity to ultrashort wavelength light, an integer of 1 to 3 is preferable, and from the viewpoint of improving sensitivity to ultrashort wavelength light while suppressing a decrease in solvent solubility, 1 or 2 is particularly preferable.

[0040] (Sulfonic acid compounds) The sulfonic acid compound is a compound having a sulfo group (-SO2OH) in the molecule, and one type can be used alone, or two or more types can be used in combination.

[0041] The sulfonic acid compound is, for example, a compound represented by the general formula [R-SO2OH]. The R is a hydrocarbon group or a group in which two or more hydrocarbon groups are bonded via a linking group. The hydrocarbon group may have a substituent.

[0042] The hydrocarbon group for R includes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which two or more of these groups are bonded via a single bond.

[0043] The aliphatic hydrocarbon group has 1 to 20 carbon atoms (=C 1-20 ) is preferred, and examples thereof include alkyl groups having about 1 to 20 carbon atoms (preferably 1 to 10, particularly preferably 1 to 3), such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, a pentyl group, a hexyl group, a decyl group, and a dodecyl group; alkenyl groups having about 2 to 20 carbon atoms (preferably 2 to 10, particularly preferably 2 to 3), such as a vinyl group, an allyl group, and a 1-butenyl group; and alkynyl groups having about 2 to 20 carbon atoms (preferably 2 to 10, particularly preferably 2 to 3), such as an ethynyl group, and a propynyl group.

[0044] Alicyclic hydrocarbon groups include C 3-20 Alicyclic hydrocarbon groups are preferred, and examples thereof include cycloalkyl groups having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 8 members), such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group; cycloalkenyl groups having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 8 members), such as a cyclopentenyl group and a cyclohexenyl group; perhydronaphthalene-1-yl group, a norbornyl group, an adamantyl group, a tricyclo[5.2.1.0 2,6 ]decan-8-yl group, tetracyclo[4.4.0.1 2,5 .1 7,10 ]Dodecan-3-yl and other bridged cyclic hydrocarbon groups are also included.

[0045] The aromatic hydrocarbon group is C 6-14 (Especially C 6-10 ) Aromatic hydrocarbon groups are preferred, such as phenyl and naphthyl groups.

[0046] The linking group is a divalent group having one or more atoms, and examples thereof include a carbonyl group (-CO-), an ether bond (-O-), a thioether bond (-S-), an ester bond (-COO-), an amide bond (-CONH-), a carbonate bond (-OCOO-), and a tetrafluorosulfanyl group (-SF4-).

[0047] The hydrocarbon group for R is preferably an aliphatic hydrocarbon group, particularly an alkyl group (e.g., C 1-20 alkyl group) is preferred.

[0048] Examples of the substituent that the hydrocarbon group in R may have include electron-withdrawing groups such as a fluorine atom and a pentafluorosulfanyl group. Among these, a fluorine atom is preferred because it is excellent in the effect of promoting the progress of the sulfonation reaction and suppressing the production of by-products.

[0049] As the R, an aliphatic hydrocarbon group which may be substituted with a fluorine atom is preferable, because it has an excellent effect of promoting the progress of the sulfonation reaction and suppressing the production of by-products. An alkyl group which may be substituted with a fluorine atom (for example, C 1-20 Alkyl groups are particularly preferred.

[0050] As the R, a fluorine atom-substituted hydrocarbon is preferable, from the viewpoint of being particularly excellent in the effect of promoting the progress of the sulfonium reaction, a fluorine atom-substituted aliphatic hydrocarbon group is preferable, and a fluorine atom-substituted alkyl group (e.g., fluoroC 1-20 Alkyl groups are particularly preferred.

[0051] In addition, the R is preferably a perfluorohydrocarbon, more preferably a perfluoroaliphatic hydrocarbon group, and even more preferably a perfluoroalkyl group (e.g., perfluoro C 1-20 Alkyl groups are particularly preferred.

[0052] Specific examples of the sulfonic acid compound include sulfonic acid, alkylsulfonic acid such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, heptanesulfonic acid, octanesulfonic acid, and nonanesulfonic acid (e.g., C 1-20Alkyl sulfonic acids; alkylaryl sulfonic acids such as toluenesulfonic acid (e.g., C 1-20 Alkylarylsulfonic acids, preferably C 1-20 alkylbenzenesulfonic acid; the alkyl group of the alkylsulfonic acid or alkylarylsulfonic acid (e.g., C 1-20 Examples of such an alkylsulfonic acid include fluoroalkylsulfonic acids (=fluorinated alkylsulfonic acids) in which at least one hydrogen atom bonded to the alkyl group (alkyl group) is substituted with a fluorine atom.

[0053] Examples of the sulfonic acid compound include fluorosulfonic acid, trifluoromethanesulfonic acid, fluoromethanesulfonic acid, difluoromethanesulfonic acid, pentafluoroethanesulfonic acid, 1,1-difluoroethanesulfonic acid, 2,2,2-trifluoroethanesulfonic acid, heptafluoropropanesulfonic acid, 1,1-difluoropropanesulfonic acid, and 3,3,3-trifluoropropanesulfonic acid, because they are particularly effective in promoting the progress of the sulfonium reaction. Preferred are fluoroalkylsulfonic acids such as nonafluorobutanesulfonic acid, 1,1,2,2-tetrafluoropropanesulfonic acid, 1,1,2,2-tetrafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, 2,2,3,3,4,4,4-heptafluorobutanesulfonic acid, 3,3,4,4,4-pentafluorobutanesulfonic acid, dodecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentadecafluoroheptanesulfonic acid, heptadecafluorooctane sulfonic acid, and octadecafluorononanesulfonic acid.

[0054] As the sulfonic acid compound, perfluoroalkylsulfonic acids such as fluorosulfonic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, dodecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentadecafluoroheptanesulfonic acid, heptadecafluorooctanesulfonic acid, and octadecafluorononanesulfonic acid are preferred, because they are particularly effective in promoting the progress of the sulfonium reaction.

[0055] (Sulfonium reaction) The sulfonium formation reaction of the present invention is carried out by reacting a sulfoxide (1) with an aryl iodide (2) in the presence of a sulfonic acid compound and diphosphorus pentoxide, substantially in the absence of a chlorinated solvent.

[0056] The amount of the aryl iodide (2) used is, for example, 1 to 100 mol, preferably 1.1 to 2 mol, relative to 1 mol of the sulfoxide (1).

[0057] The amount of the sulfonic acid compound used per mole of sulfoxide (1) is 2 moles or more. From the viewpoint of further promoting the progress of the sulfonium reaction and further suppressing the progress of side reactions, the amount of the sulfonic acid compound used is particularly preferably 2.5 moles or more, most preferably 3 moles or more, and particularly preferably 4 moles or more. The amount of the sulfonic acid compound used is, for example, preferably 10 moles or less, particularly preferably 7 moles or less, and most preferably 6 moles or less.

[0058] Diphosphorus pentoxide is a compound that acts as a dehydrating agent. In the reaction of sulfoxide (1) with aryl iodide (2), H2O is generated, and removing the generated H2O has the effect of promoting the progress of the sulfonation reaction. The amount of diphosphorus pentoxide used per mole of sulfoxide (1) is 0.3 to 10 moles. From the viewpoint of further promoting the progress of the sulfonation reaction and further suppressing the progress of side reactions, the lower limit of the amount of diphosphorus pentoxide used is preferably 0.5 moles, and particularly preferably 0.6 moles. The upper limit of the amount of diphosphorus pentoxide used is preferably 5 moles, particularly preferably 3 moles, and most preferably 1.5 moles.

[0059] Other compounds acting as dehydrating agents besides diphosphorus pentoxide may be used in combination, but the use of an acid anhydride such as trifluoromethanesulfonic anhydride tends to easily produce a by-product sulfonium salt represented by formula (3b) described below. Therefore, from the viewpoint of suppressing the production of by-products, the amount of the other dehydrating agent (particularly the acid anhydride) used is preferably, for example, 0.5 mol or less relative to the amount of diphosphorus pentoxide used (1 mol), from the viewpoint of obtaining the effect of promoting the progress of the sulfonation reaction, more preferably 0.1 mol or less, most preferably 0.05 mol or less, and particularly preferably 0.01 mol or less.

[0060] The sulfonium reaction is carried out in the substantial absence of a chlorine-based solvent, which has the effect of promoting the progress of the sulfonium reaction and suppressing the progress of side reactions.

[0061] Examples of the chlorine-based solvent include dichloromethane, chloroform, carbon tetrachloride, chloroethane, 1-chloropropane, 2-chloro-2-methylpropane, 1,2-dichloroethane, 1,2-dichloropropane, and 1,1,2,2-tetrachloroethane.

[0062] In the present invention, "chlorine-based solvent is substantially absent" means that no chlorine-based solvent is present in the reaction system in an amount that affects the sulfonation reaction, and the presence of a chlorine-based solvent in an amount that does not affect the sulfonation reaction is permitted. The amount of chlorine-based solvent that does not affect the sulfonation reaction is, for example, 10% by weight or less, preferably 5% by weight or less, particularly preferably 3% by weight or less, and most preferably 1% by weight or less, based on the total content of sulfoxide (1) and aryl iodide (2).

[0063] The sulfonium formation reaction may contain a solvent other than a chlorine-based solvent (hereinafter referred to as "other solvent". Examples of other solvents include n-heptane, cyclohexane, and benzotrifluoride). From the viewpoint of promoting the progress of the sulfonium formation reaction and suppressing the progress of side reactions, the content of the other solvents (total amount when two or more types are contained) is preferably 10% by weight or less, particularly preferably 7% by weight or less, most preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total content of the sulfoxide (1) and aryl iodide (2). In other words, the sulfonium formation reaction is preferably carried out in the substantial absence of a solvent.

[0064] In the present invention, the "solvent" refers to a low molecular weight compound (having a molecular weight of, for example, 200 or less) that is liquid at room temperature and pressure and can be removed by heating or reducing pressure, and is a compound that dissolves the sulfoxide (1) and the aryl iodide (2).

[0065] The reaction temperature of the sulfonium formation reaction is preferably from -20°C to 60°C, particularly preferably from -5°C to 50°C, and most preferably from 15°C to 45°C, from the viewpoint of further promoting the progress of the sulfonium formation reaction and further suppressing the progress of side reactions.

[0066] The reaction atmosphere for the sulfonium formation reaction is not particularly limited as long as it does not inhibit the reaction, and may be, for example, any of an air atmosphere, a nitrogen atmosphere, an argon atmosphere, and the like.

[0067] The sulfonation can be carried out by any method such as a batch method, a semi-batch method, or a continuous method.

[0068] After completion of the sulfonium-forming reaction, the resulting reaction product can be separated and purified by a separation means such as filtration, concentration, distillation, extraction, crystallization, adsorption, recrystallization, column chromatography, or a combination of these.

[0069] The sulfonium reaction gives the following triarylsulfonium salt (3) as the main product.

[0070] The yield of the triarylsulfonium salt (3) is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 83% by weight or more, particularly preferably 85% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more.

[0071] In the sulfonium reaction, there is a possibility that a by-product sulfonium salt represented by the following formula (3b) is produced from two molecules of sulfoxide (1), but in the present invention, the production of the by-product is suppressed, and the yield of the product is, for example, 15% by weight or less, preferably 10% by weight or less, particularly preferably 5% by weight or less, and most preferably 3% by weight or less. f 1 , R f 2 , n1, n2, X - is the same as above. [ka]

[0072] Furthermore, in the sulfonium reaction, there is a possibility that the sulfoxide (1) is reduced to produce a sulfide represented by the following formula (1b), but in the present invention, the production of the sulfide is suppressed, and the yield of the following product is, for example, 5% by weight or less, preferably 3% by weight or less, particularly preferably 2% by weight or less, most preferably 1% by weight or less, and particularly preferably 0.5% by weight or less. f 1 , R f 2 , n1, and n2 are the same as above. [ka]

[0073] Furthermore, in the present invention, since the sulfonation reaction proceeds rapidly, the amount of the raw material sulfoxide (1) remaining is suppressed, and the proportion of the remaining sulfoxide (1) in the reaction product is, for example, 15% by weight or less, preferably 10% by weight or less, more preferably 8% by weight or less, particularly preferably 5% by weight or less, and most preferably 3% by weight or less of the total amount of the reaction product.

[0074] (Triarylsulfonium salt (3)) The triarylsulfonium salt (3) is a compound represented by the above formula (3). f 1 , R f 2 , R 1 , n1, n2, and n3 are the same as above.

[0075] In the above formula (3), X - represents an anion derived from the sulfonic acid compound, and is preferably an alkylsulfonate anion, particularly preferably a fluoroalkylsulfonate anion, and most preferably a perfluoroalkylsulfonate anion.

[0076] Triarylsulfonium salt (3) is a compound that has benzene rings A and B derived from sulfoxide (1) and benzene ring C derived from aryl iodide (2).

[0077] And the substituents of the benzene ring C (iodine atom and n3 R 1 The bonding position of the substituents (iodine atom and n3 R groups) of the aryl iodide (2) used is determined by the 1 It varies depending on the number and bonding position of the alkyl group.

[0078] For example, when an aryl iodide represented by the following formula (2-1) is used as the aryl iodide (2) to carry out a sulfonation reaction [1], a triarylsulfonium salt having an iodine atom at the para-position to the sulfur atom represented by the following formula (3-1) is selectively obtained. f 1 , R f 2, n1, n2, X - is the same as above. [ka]

[0079] In the case of [1] above, the content of the compound represented by the formula (3-1) in the reaction product is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 83% by weight or more, particularly preferably 85% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more. The content of the positional isomer of the compound represented by the formula (3-1) in the reaction product (total amount when two or more kinds are contained) is, for example, 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 3% by weight or less.

[0080] The positional isomer of the compound represented by the above formula (3-1) is, for example, a triarylsulfonium salt having an iodine atom at the ortho- or meta-position relative to the sulfur atom.

[0081] When an aryl iodide represented by the following formula (2-2) is used as the aryl iodide (2) to carry out a sulfonation reaction [2], a triarylsulfonium salt having an iodine atom at the para-position to the sulfur atom represented by the following formula (3-2) is selectively obtained. f 1 , R f 2 , n1, n2, n3, X - is the same as above. [ka]

[0082] In the case of [2] above, the content of the compound represented by the above formula (3-2) in the reaction product is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 83% by weight or more, particularly preferably 85% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more. The content of the positional isomer of the compound represented by the above formula (3-1) in the reaction product (total amount when two or more kinds are contained) is, for example, 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, even more preferably 15% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 3% by weight or less.

[0083] The positional isomer of the compound represented by the above formula (3-2) is, for example, a triarylsulfonium salt having an iodine atom at the ortho- or meta-position relative to the sulfur atom.

[0084] When an aryl iodide represented by the following formula (2-3) is used as the aryl iodide (2) to carry out a sulfonium reaction [3], the aryl iodide represented by the following formula (3-3) is attached to the para position of the sulfur atom. 1 In the following formula, R f 1 , R f 2 , n1, n2, X - is the same as above. 1 represents a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group. [ka]

[0085] In the case of [3] above, the content of the compound represented by the formula (3-3) in the reaction product is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 83% by weight or more, particularly preferably 85% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more. The content of the positional isomer of the compound represented by the formula (3-1) in the reaction product (total amount when two or more kinds are contained) is, for example, 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 3% by weight or less.

[0086] The positional isomers of the compound represented by the above formula (3-3) include, for example, R 1 It is a triarylsulfonium salt having a ' group.

[0087] When an aryl iodide represented by the following formula (2-4) is used as the aryl iodide (2) to carry out a sulfonium reaction [4], the aryl iodide represented by the following formula (3-4) is attached to the para position of the sulfur atom. 1 In the following formula, R f 1 , R f 2 , n1, n2, X - is the same as above. 1 n' represents a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group; n4 represents an integer of 1 to 3, and is preferably 1 or 2. [ka]

[0088] In the case of [4] above, the content of the compound represented by the above formula (3-4) in the reaction product is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 83% by weight or more, particularly preferably 85% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more. The content of the positional isomer of the compound represented by the above formula (3-1) in the reaction product (total amount when two or more kinds are contained) is, for example, 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 3% by weight or less.

[0089] The positional isomers of the compound represented by the above formula (3-4) include, for example, R 1 It is a triarylsulfonium salt having a ' group.

[0090] The chemical structure of the triarylsulfonium salt (3) is, for example, 1 H-, 11 B-, 13 C-, 19 F-, or 31 The compound can be identified by P-nuclear magnetic resonance spectroscopy, infrared absorption spectroscopy, elemental analysis, or the like.

[0091] The triarylsulfonium salt (3) thus obtained has high photosensitivity to light rays with ultrashort wavelengths, such as EUV (extreme ultraviolet), EB (electron beam), and X-rays. Furthermore, even without using a photosensitizer, light energy is directly transmitted to the triarylsulfonium salt (3) by simply irradiating it with light of the above wavelengths, and photodecomposition proceeds rapidly, resulting in the production of an acid (H + X - :X - is the same as above).

[0092] In addition, the triarylsulfonium salt (3) has excellent solubility in organic solvents.

[0093] Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; carbonates such as propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate; linear or cyclic esters such as ethyl acetate, butyl acetate, and ethyl lactate, β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone; ethylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monoethyl ... Examples of the glycol diethers include propylene glycol dimethyl ether, triethylene glycol diethyl ether, and tripropylene glycol dibutyl ether; glycol monoether monoesters include ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; and ketones include acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone. These may be used alone or in combination of two or more.

[0094] The organic solvent preferably contains at least one selected from the group consisting of ketones, chain esters, and glycol monoether monoesters.

[0095] The solubility of the triarylsulfonium salt (3) in an organic solvent (e.g., PGMEA) at 25° C. is, for example, 2% by weight or more (e.g., 2 to 50% by weight), preferably 3% by weight or more, more preferably 4% by weight or more, and particularly preferably 5% by weight or more. Therefore, by adding the triarylsulfonium salt (3) together with a solvent to a photoresist, the triarylsulfonium salt (3) can be uniformly dispersed in the photoresist.

[0096] Because the triarylsulfonium salt (3) has the above-mentioned properties, it can be suitably used as an acid generator (e.g., a photoacid generator) for use in photoresists (e.g., positive-type photosensitive resins and negative-type photosensitive resins).

[0097] The above-mentioned configurations and combinations of the present invention are merely examples, and the configurations can be added, omitted, substituted, and modified as appropriate without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments, but is limited only by the claims. EXAMPLES

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0099] Preparation Example 1 (Preparation of Sulfoxide (A-2)) A tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide was prepared by a conventional method using 96.5 g (0.5 mol) of 1-bromo-3,5-difluorobenzene, 13.4 g (0.55 mol) of magnesium, and 400 g of tetrahydrofuran.

[0100] To the resulting tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide, a solution prepared by diluting 28.6 g (0.48 mol) of thionyl chloride with 50 g of tetrahydrofuran was added dropwise within a range in which the temperature in the system did not exceed −5° C. After the dropwise addition, the reaction was continued at room temperature for 1 hour to complete the reaction. This solution was added to 500 g of ion-exchanged water so that the temperature in the system did not exceed 15°C, and the mixture was stirred for 1 hour. Then, 300 g of ethyl acetate was added and the mixture was stirred for 1 hour. After removing the aqueous layer, the mixture was washed three times with 300 g of ion-exchanged water. The organic layer was desolvated, and the obtained brown residue was recrystallized with cyclohexane to obtain 26.0 g of bis(3,5-difluorophenyl)sulfoxide.

[0101] Preparation Example 2 (Preparation of Sulfoxide (A-1)) Bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide was obtained in the same manner as in Preparation Example 1, except that 146.5 g (0.5 mol) of 1-bromo-3,5-bis(trifluoromethyl)benzene was used instead of 96.5 g of 1-bromo-3,5-difluorobenzene.

[0102] Example 1 (Preparation of Sulfonium Salt) 1.0 g of the bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide obtained in Preparation Example 2 as the sulfoxide (1), 0.86 g of iodobenzene as the aryl iodide (2), 1.6 g of trifluoromethanesulfonic acid (corresponding to 5.1 mol relative to 1 mol of the sulfoxide) as a sulfonic acid compound, and 0.33 g of PO (corresponding to 1.1 mol relative to 1 mol of the sulfoxide) were reacted with each other at 45° C. for 90 minutes under stirring (sulfonium formation reaction). Thereafter, 30 g of ion-exchanged water and 16 g of an organic solvent (dichloromethane) were added to the reaction system and stirred, after which the aqueous layer was removed and the organic layer was washed three times with 10 g of ion-exchanged water.

[0103] The organic layer after washing was desolvated to obtain a reaction product, whose composition was 1 H-NMR and 19 The product was analyzed using F-NMR. As a result, it was found to contain a sulfonium salt represented by the following formula (3-1a'), a by-product sulfonium salt represented by the following formula (3b-1), and unreacted bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide. The positional isomer of the sulfonium salt represented by the following formula (3-1a') was not contained.

[0104] [ka]

[0105] Examples 2 to 7 The sulfonation reaction was carried out in the same manner as in Example 1, except that the sulfoxide (1), the aryl iodide (2), and the sulfonic acid compound were changed as shown in the table below, to obtain a reaction product, and the composition of the obtained reaction product was analyzed.

[0106] Comparative Example 1 (Preparation of Sulfonium Salt) 1.0 g of the bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide obtained in Preparation Example 2 as sulfoxide (1), 0.86 g of iodobenzene as aryl iodide (2), 1.6 g of trifluoromethanesulfonic acid (corresponding to 5 mol per mol of the sulfoxide) as a sulfonic acid compound, 0.33 g of PO (corresponding to 1.1 mol per mol of the sulfoxide), and 9.4 g of dichloromethane were reacted with stirring at 45° C. for 90 minutes (sulfonium formation reaction). Thereafter, 30 g of ion-exchanged water and 16 g of an organic solvent (dichloromethane) were added to the reaction system and stirred, after which the aqueous layer was removed and the organic layer was washed three times with 10 g of ion-exchanged water.

[0107] The organic layer after washing was desolvated to obtain a reaction product. The composition of the reaction product was 1 H-NMR and 19 The analysis was carried out using F-NMR.

[0108] Comparative Examples 2 to 5 A sulfonium-forming reaction was carried out in the same manner as in Comparative Example 1, except that the sulfoxide (1), the sulfonic acid compound, the dehydrating agent, and the solvent were changed as shown in the table below, to obtain a reaction product, and the composition of the obtained reaction product was analyzed.

[0109] [Table 1]

[0110] The abbreviations in the above formula are explained below. <Sulfoxide (1)> A-1: Bis[3,5-bis(trifluoromethyl)phenyl]sulfoxide obtained in Preparation Example 2 A-2: Bis(3,5-difluorophenyl)sulfoxide obtained in Preparation Example 1 <Aryl iodide (2)> B-1: Iodinated benzene B-2: 1,3-diiodobenzene B-3: 1,2-diiodobenzene B-4: 1-iodo-3-methoxybenzene B-5: 2,4,6-Triiodophenol <Sulfonic acid compounds> TfOH: Trifluoromethanesulfonic acid MsOH: methanesulfonic acid <Dehydrating agent> TfO: Trifluoromethanesulfonic anhydride <Sulfonium salt (3)> 3-1a: A sulfonium salt having a cation represented by the following formula (3-1a) and an anion derived from a sulfonic acid compound. 3-1a': a sulfonium salt having a cation represented by the following formula (3-1a) and a trifluoromethanesulfonate anion: 3-2a: A sulfonium salt having a cation represented by the following formula (3-2a) and an anion derived from a sulfonic acid compound. 3-3a: A sulfonium salt having a cation represented by the following formula (3-3a) and an anion derived from a sulfonic acid compound. 3-4a: A sulfonium salt having a cation represented by the following formula (3-4a) and an anion derived from a sulfonic acid compound. 3-5a: A sulfonium salt having a cation represented by the following formula (3-5a) and an anion derived from a sulfonic acid compound. 3-6a: A sulfonium salt having a cation represented by the following formula (3-6a) and an anion derived from a sulfonic acid compound. [ka]

[0111] From Table 1, it is clear that according to the method of the present invention, the sulfonium formation reaction can be efficiently carried out, the target sulfonium salt can be obtained in high yield, and the production of by-products can be suppressed.

[0112] (Photosensitivity Evaluation) The photosensitivity of the sulfonium salt obtained in Example 1 was evaluated by the following method. That is, the sulfonium salt obtained in Example 1 was diluted with acetonitrile to a molar concentration of 2.5 mM, and rhodamine B base (an acid coloring reagent, manufactured by Sigma-Aldrich) was added to a molar concentration of 2.5 mM to prepare a sample solution.

[0113] The obtained sample solution was placed in a quartz cell with an optical path length of 1 cm, and EB exposure was performed using an EB exposure device (JEOL JBX-9300, manufactured by JEOL Ltd.) at an acceleration voltage of 100 kV and an accumulated light intensity of 100 μC / cm. 2 The electron beam exposure was carried out under the following conditions. When the sulfonium salt in the sample solution is decomposed by exposure to light and an acid is generated, the generated acid reacts with the rhodamine B base, increasing the absorbance at 556 nm. Therefore, the amount of generated acid can be determined by measuring the absorbance at 556 nm after exposure. The absorbance was measured using a spectrophotometer (UV-vis). The acid concentration in the sample solution after exposure was quantified from the absorbance at 556 nm of the sample solution after exposure using a calibration curve (standard substance: p-toluenesulfonic acid). The acid generation rate was calculated from the following formula, and the photosensitivity was evaluated from the calculated acid generation rate according to the following criteria. Acid generation rate (%) = acid concentration after exposure (mM) / sulfonium salt concentration before exposure (mM) × 100

[0114] As a result, the acid generation rate was 40% or more. As described above, according to the method of the present invention, the compound has excellent sensitivity to EB (electron beam) light, and is easily decomposed into an acid (H + X - It was found that a sulfonium salt which generates

Claims

1. The following formula (1) 【Chemistry 1】 (In the formula, R f 1 , R f 2 are the same or different and each represents a fluorine atom or a fluoroalkyl group; n1 and n2 are the same or different and each represents an integer of 1 or more. and a compound represented by the following formula (2): 【Chemistry 2】 (In the formula, R 1 represents an iodine atom, a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group; and n3 represents an integer of 0 or more. in the presence of 0.3 to 10 moles of diphosphorus pentoxide per mole of the compound represented by formula (1) and in the substantial absence of a chlorine-based solvent, to obtain a compound represented by formula (3): 【Chemistry 3】 (In the formula, X - R represents an anion derived from the sulfonic acid compound. f 1 , R f 2 , R 1 , n1, n2, and n3 are the same as above. The method for producing a sulfonium salt according to the present invention provides a sulfonium salt represented by the following formula:

2. The method for producing a sulfonium salt according to claim 1, wherein the sulfonic acid compound is a fluorinated alkylsulfonic acid.

3. 3. The method for producing a sulfonium salt according to claim 1, wherein the reaction gives a product having the following composition: <Product composition> Content of the compound represented by formula (1): 15% by weight or less Content of the sulfonium salt represented by formula (3): 70% by weight or more Content of the sulfonium salt represented by the following formula (3b): 15% by weight or less 【Chemistry 4】 (In the formula, R f 1 , R f 2 , n1, n2, X - is the same as above)

4. 3. The method for producing a sulfonium salt according to claim 1, wherein the reaction is carried out substantially in the absence of a solvent.

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