JP5116311B2 - Sulfonium salt - Google Patents

Description

  The present invention is a photoacid generator that decomposes easily upon irradiation with actinic radiation such as deep UV, electron beam, X-ray or EUV (extreme ultraviolet) to generate an acid, particularly a photoacid generator for a chemically amplified photoresist material. The present invention relates to a sulfonium salt useful as an agent.

  In a highly integrated circuit element typified by a semiconductor device such as a DRAM, there is a strong demand for higher density, higher integration, or higher speed. Along with this, in various electronic device manufacturing fields, there is an increasing demand for the establishment of fine processing technology on the order of half a micron, for example, the development of photolithography technology for forming fine patterns. In the photolithography technique, as one of means for miniaturizing a pattern, there is a method of shortening the wavelength of actinic radiation (exposure light) used in forming a photoresist pattern. Here, the resolution (R) of the reduction projection exposure apparatus is expressed by the Rayleigh equation R = k · λ / NA (λ is the wavelength of exposure light, NA is the numerical aperture of the lens, and k is a process factor). The resolution can be improved by shortening the wavelength λ of the actinic radiation (exposure light) used in forming the resist pattern.

  As a photoresist suitable for a short wavelength, a chemically amplified type has been proposed (see Patent Document 1). A characteristic of chemically amplified photoresists is that proton acid is generated by exposure to exposure light from a photoacid generator, which is a component, and this protonic acid undergoes an acid-catalyzed reaction with a polymer such as resist resin by heat treatment after exposure. That is, most of the photoresists currently developed are chemically amplified.

  Various sulfonium salts are known as photoacid generators for such chemically amplified photoresists. However, conventional sulfonium salt photoacid generators have problems such as poor compatibility with polymers having acid dissociable groups (groups that dissociate and decompose with acid), which are the main components of photoresists. As a matter of course, due to the problem, when the photoresist containing the photoacid generator is subjected to pattern exposure with actinic radiation, there is a problem in that the obtained pattern shape does not become a desired shape and has an adverse effect. Arise.

U.S. Pat. No. 4,491,628

  In view of such circumstances, the present invention is not accompanied by the problem of poor compatibility between the acid generator and the polymer having an acid dissociable group, which is the main component of the photoresist, and functions as a photoacid generator. It is an object of the present invention to provide a sulfonium salt having

  A first aspect of the present invention for solving the above problem is a sulfonium salt represented by the following formula (1).

In (Equation (1), ^{R 1} and ^{R 2} each independently represent a hydrogen atom, a methyl group, an isopropyl group, t- butyl group, a cyclohexyl group, or, .D ¹ representing a an alkoxy group having 1 to 12 carbon atoms And D ² are mutually independent, at least one is a group represented by the following formula (2), and the remainder is represented by a hydrogen atom, a group represented by the following formula (3) or the following formula (4). A, b, c, and d are integers of 0 or more that satisfy a + b ≦ 5, c + d ≦ 5, and a + c ≧ 1, respectively, and W represents C 2 O. )

(In Formula (2), R ³ is a linear or branched divalent alkylene group having 2 to 8 carbon atoms, R ^{4 to} R ⁷ are each independently a hydrogen atom or a methyl group , and R ⁸ and R ⁹ are each independently a phenyl group, methylphenyl group or t- butylphenyl group .X ^- represents an anion).

(In Formula (3), R ¹⁰ represents a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms or an optionally substituted aromatic group having 6 to 30 carbon atoms.)

A second aspect of the present invention is the sulfonium salt according to the first aspect, wherein the anion represented by X ⁻ is an anion represented by the following formula (5).

(In Formula (5), k, m, and n each independently represent an integer of 0 or more. When m is 0, k is an integer of 1 to 8, n is 2k + 1, and Formula (5) is A perfluoroalkylsulfonate ion, when n is 0, k is an integer of 1 to 15, m is an integer of 1 or more, and formula (5) is an alkylsulfonate ion, a benzenesulfonate ion, or an alkylbenzenesulfonate ion. When m and n are each independently an integer of 1 or more, k is an integer of 1 to 10, and the formula (5) is a fluorine-substituted benzenesulfonate ion, a fluorine-substituted alkylbenzenesulfonate ion, or a fluorine-substituted alkylsulfonate ion.)

According to a third aspect of the present invention, in the first aspect, the anion represented by X ⁻ is a bis (perfluoroalkylsulfone) imide ion represented by the following formula (6). Of the sulfonium salt.

(In the formula, p represents an integer of 1 to 8.)

A fourth aspect of the present invention is the sulfonium salt according to the first aspect, wherein the anion represented by X ⁻ is an anion represented by the following formula (7).

According to a fifth aspect of the present invention, the anion represented by X ⁻ is Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ or PF ₆ ^−. In the sulfonium salt according to the first embodiment.

  According to the present invention, it is possible to provide a sulfonium salt having a structure having a function as a photoacid generator and an acid dissociation group. Since this sulfonium salt can be made into a chemically amplified photosensitive composition by itself in a solvent without containing an acid generator, the compatibility between the acid generator and a polymer having an acid-dissociable group There is no problem of being bad, and there is an effect that a pattern having a good shape can be obtained.

Hereinafter, the present invention will be described in detail.
The sulfonium salt of the present invention is a compound represented by the above formula (1). In Formula (1), R ¹ and R ² each independently represent a hydrogen atom, a linear, branched, alicyclic or aromatic organic group having 1 to 12 carbon atoms or an alkoxy group. Particularly preferred organic groups include a methyl group, an isopropyl group, a t-butyl group, and a cyclohexyl group. D ¹ and D ² are independent of each other, and at least one is a group represented by the above formula (2), and the rest is a hydrogen atom, a group represented by the above formula (3) or the above formula (4). It is group represented by these. Further, a, b, c, and d are integers of 0 or more that satisfy a + b ≦ 5, c + d ≦ 5, and a + c ≧ 1, respectively. The group represented by the formula (2) is a structure having a function as a photoacid generator that generates an acid upon exposure to actinic radiation, and a group that can be dissociated by an acid generated from the acid generator (acid dissociation group) Therefore, the sulfonium salt represented by the formula (1) can be made into a chemically amplified photosensitive composition by dissolving in a solvent. In the sulfonium salt represented by the formula (1), the group represented by the formula (3) or the group represented by the formula (4) may not be introduced, but the group represented by the formula (3) And solubility can be adjusted by introduce | transducing group represented by Formula (4). When introducing the group represented by the formula (3) or the group represented by the formula (4), about 1 to 3 equivalents are respectively preferable with respect to the sulfonium salt represented by the formula (1). W represents CO, SO ₂ or an ether bond.

In the group represented by the formula (2), R ³ is a linear or branched divalent organic group having 2 to 9 carbon atoms, and R ^{4 to} R ⁷ are each independently a hydrogen atom or a direct group. It is a chain or branched organic group having 1 to 3 carbon atoms. R ⁸ and R ⁹ are each independently an organic group. Examples of the organic group include a linear, branched or alicyclic alkyl group. Examples of organic groups include carbocyclic aryl groups and heterocyclic aryl groups. Preferred organic groups are carbocyclic aryl groups, and particularly preferred organic groups are phenyl group, methylphenyl group and t-butylphenyl group. Said carbocyclic aryl group and heterocyclic aryl group may have a C1-C30 substituent. As a C1-C30 substituent, a C1-C30 organic group or an alkoxy group is preferable. Examples of the organic group having 1 to 30 carbon atoms as a substituent include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, and a heptyl group. Group, octyl group, t-amyl group, decanyl group, dodecanyl group, hexadecanyl group and other alkyl groups, cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, cyclododecanyl group, cyclohexadecanyl group and adamantyl And alicyclic alkyl groups such as a group, and aryl groups such as a phenyl group and a naphthyl group. Examples of the alkoxy group having 1 to 30 carbon atoms as a substituent include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a t-butoxy group, and pentyl. Examples thereof include an oxy group, a t-amyloxy group, an n-hexyloxy group, an n-octyloxy group, an n-dodecanoxy group, and a 1-adamantyloxy group.

R ⁸ and R ⁹ may be bonded to each other to form a ring. In this case, the divalent organic group containing the carbon skeleton is —R ⁸ —R ⁹ —. Examples of such a divalent organic group include an alicyclic alkyl group having 3 to 9 carbon atoms in which R ⁸ and R ⁹ are connected with a saturated carbon skeleton. Preferred examples of the alicyclic alkyl group include polymethylene groups such as a tetramethylene group and a pentamethylene group. In general, the ring formed by the divalent organic group —R ⁸ —R ⁹ — together with S is preferably a 4- to 8-membered ring, more preferably a 5- to 6-membered ring.

R ¹⁰ in the formula (3) represents a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 30 carbon atoms which may have a substituent. Among these alkyl groups and aromatic groups, preferred are alicyclic alkyl groups and carbocyclic aryl groups, and particularly preferred are cyclohexyl group, tricyclodecanyl group, adamantyl group, phenyl group, naphthyl group. And a diphenylmethyl group. The carbocyclic aryl group may have a substituent having 1 to 24 carbon atoms. As a C1-C24 substituent, a C1-C24 organic group or an alkoxy group is preferable. Examples of the substituted organic group having 1 to 24 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, and a heptyl group. Group, octyl group, t-amyl group, decanyl group, dodecanyl group, hexadecanyl group and other alkyl groups, cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, cyclododecanyl group, cyclohexadecanyl group and adamantyl group And alicyclic alkyl groups such as a group, and aryl groups such as a phenyl group and a naphthyl group. Examples of the substituted alkoxy group having 1 to 24 carbon atoms include methoxy group, ethoxy group, propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, and pentyl. Examples thereof include an oxy group, a t-amyloxy group, an n-hexyloxy group, an n-octyloxy group, an n-dodecanoxy group, and a 1-adamantyloxy group.

In formula (2), the anion represented by X ⁻ is not particularly limited, and can be an anion conventionally used for a photoacid generator. Examples of the anion include an anion represented by the above formula (5), an anion represented by the above formula (6), or an anion represented by the above formula (7) (cyclo 1,3-perfluoropropane. Disulfonimide ion). Other anions represented by X ⁻ include halide ions such as Cl ⁻ , Br ⁻ and I ⁻ , BF ₄ ⁻ (tetrafluoroborate ion), AsF ₆ ⁻ (hexafluoroarsenate ion), SbF 6 _- ^{(hexafluoroantimonate} ion) and PF 6 _- ^{(hexafluorophosphate} ion) inorganic anions of fluoride ions, etc., and the like.

In Formula (5), k, m, and n each independently represent an integer of 0 or more. When m is 0, k is an integer of 1 to 8, n is 2k + 1, and Formula (5) It is a fluoroalkylsulfonate ion. Examples of suitable perfluoroalkyl sulfonate ion, _{CF 3} SO 3 ^- (trifluoromethanesulfonate _{ion), C 4 F 9 SO 3} - ( nonafluorobutanesulfonate ion) and _C 8 _F 17 SO ₃ ^- (heptadecafluorooctanesulfonic Sulfonate ion) and the like.

In the formula (5), when n is 0, k is an integer of 1 to 15, m is an integer of 1 or more, and the formula (5) is an alkyl sulfonate ion, a benzene sulfonate ion or an alkyl benzene sulfonate ion. is there. In the case of alkyl sulfonate ions, m is represented by 2k + 1. Examples of suitable alkyl sulfonate ion, _CH 3 SO ₃ ^- (methanesulfonate _{ion), C 2 H 5 SO 3} - or (1-nonanoic sulfonate ion), etc., - (ethane sulfonate _{ion), C} 9 H 19 _SO ³ Examples include bridged cyclic alkyl sulfonate ions such as 10-camphor sulfonate ions. Examples of suitable alkylbenzenesulfonate ions include 4-methylbenzenesulfonate ion and 2,4,6-triisopropylbenzenesulfonate ion.

  Further, in the formula (5), when m and n are each independently an integer of 1 or more, k is an integer of 1 to 10, and the formula (5) is a fluorine-substituted benzenesulfonate ion or a fluorine-substituted alkylbenzenesulfonate ion. Or a fluorine-substituted alkylsulfonate ion. Examples of suitable fluorine-substituted benzenesulfonate ions include 2-fluorobenzenesulfonate ion, 4-fluorobenzenesulfonate ion, 2,4-difluorobenzenesulfonate ion, and pentafluorobenzenesulfonate ion. Also, examples of suitable fluorine-substituted alkylbenzenesulfonate ions include 2-trifluoromethylbenzenesulfonate ion, 4-trifluoromethylbenzenesulfonate ion, 2,4-bis (trifluoromethyl) benzenesulfonate ion, and 3,5-bis (Trifluoromethyl) benzenesulfonate ion and the like can be mentioned. Furthermore, as a suitable example of the fluorine-substituted alkyl sulfonate, 1,1,2,3,3,3-hexafluoropropane sulfonate ion may be mentioned.

  On the other hand, the anion represented by Formula (6) is a bis (perfluoroalkylsulfone) imide ion, and p is an integer of 1 to 8. Examples of suitable bis (perfluoroalkylsulfone) imide ions include bis (trifluoromethanesulfone) imide ions and bis (pentafluoroethanesulfone) imide ions.

  The sulfonium salt of the present invention described above has a structure having a function as a photoacid generator that efficiently generates an acid upon irradiation with actinic radiation (for example, deep UV, electron beam, X-ray, EUV), and the acid generation. The sulfonium salt represented by formula (1) can be easily made into a chemically amplified photosensitive composition by dissolving it in an organic solvent. . Therefore, there is an effect that a pattern having a good shape can be obtained without causing the problem of poor compatibility between the acid generator and the polymer having an acid dissociable group which is the main component of the photoresist.

  Although the manufacturing method of the sulfonium salt of this invention is not specifically limited, For example, it can manufacture by making the phenolic compound represented by following formula (A) react with following formula (12). An example of a manufacturing method is shown below.

First, as shown in the following reaction formula, a compound represented by formula (8) is reacted with dialkyl sulfoxide in methanesulfonic acid (CH ₃ SO ₃ H) using niline pentoxide (P ₂ O ₅ ) as a catalyst. To obtain a compound (methanesulfonate) represented by the formula (9). Dialkyl sulfoxide can be easily obtained by oxidizing a dialkyl sulfide with hydrogen peroxide. In addition, niline pentoxide as a catalyst is used in an amount of 0.1 to 3.0 mol, preferably 0.5 to 1.5 mol, per 1 mol of the compound represented by the formula (8). Methanesulfonic acid is used in an amount of 1 to 10 mol, preferably 4 to 6 mol, per 1 mol of the compound represented by formula (8). The reaction temperature is usually 0 to 50 ° C., preferably 10 to 30 ° C., and the reaction time is usually 1 to 15 hours, preferably 3 to 8 hours. After completion of the reaction, the reaction is stopped by adding water.

Next, as shown in the following reaction formula, CH ₃ SO ₃ ^— of the compound represented by formula (9) is subjected to salt exchange with X ⁻ . In the following reaction formula, M ⁺ represents a monovalent metal ion. Specifically, in an aqueous solution of the compound represented by the formula (9), X ⁻ , for example, various acids H ⁺ X ⁻ or the salt M ⁺ containing the above formula (5), formula (6) or formula (7). X ^- a, 1-2 moles per mole of the compound represented by the formula (8), preferably added 1.05-1.2 mole. As the reaction solvent, it is preferable to use a chlorinated solvent such as dichloromethane or chloroform. Moreover, reaction temperature is 10-50 degreeC normally, Preferably it is 20-30 degreeC. After completion of the reaction, the aqueous layer is separated and the organic layer is washed with water. After completion of washing, the compound represented by the formula (9) can be obtained by crystallization with an appropriate solvent. In addition, after producing | generating the compound represented by Formula (8), potassium iodide was added to the reaction solution, and the compound represented by Formula (9) was taken out as a solid by carrying out salt exchange to an iodine ion, and refine | purified after refinement | purification for X objects ^- in may be salt exchange, also for the purified product may be salt exchange with a sulfonic acid ester.

Thereafter, as shown in the following reaction formula, a dehydrohalogenation reaction is performed using the compound represented by the formula (10) and the compound represented by the formula (11), thereby expressing the formula (12). Can be obtained. In the following reaction formula, Y represents a halogen atom such as Cl and Br. Specifically, for example, a compound represented by formula (10) and a compound represented by formula (11) are reacted in the presence of a basic catalyst such as potassium carbonate (K ₂ O ₃ ) in a polar solvent. Let The reaction temperature is usually 60 to 90 ° C. The compound represented by Formula (12) can be obtained by distilling a solvent off after completion | finish of reaction. In addition, what is marketed can also be used for the compound of Formula (8)-Formula (11).

  When the compound represented by the formula (12) and the phenol compound represented by the following formula (A) are reacted in an organic solvent under an acidic catalyst, —OH of the phenol compound represented by the formula (A) Can react with the double bond site of the compound represented by the formula (12) to produce the sulfonium salt represented by the above formula (1). As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, trifluoroacetic acid and the like can be used. As the organic solvent, ethers such as tetrahydrofuran (THF), 1,3-dioxolane and 1,3-dioxane, and propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether acetate can be used. Specific examples of the phenol compound represented by the above formula (A) include phenol compounds represented by the following formulas (a-1) to (a-21).

(The symbols in the formula are the same as those in the formula (1).)

  In addition, the group represented by the formula (3) is an organic compound such as 1,3-dioxolane, propylene glycol monomethyl ether, or the like, by adding a vinyl ether represented by the following formula (13) to the phenol compound represented by the above formula (A). It can introduce | transduce by carrying out an addition reaction in presence of an acidic catalyst in a solvent. As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, trifluoroacetic acid and the like can be used.

(R ¹⁰ represents a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms or an optionally substituted aromatic group having 6 to 30 carbon atoms.)

  In addition, the group represented by the formula (4) includes di-t-butyl dicarbonate represented by the following formula (14) and a phenol compound represented by the above formula (A), 1,3-dioxolane, etc. It can introduce | transduce by making it react in an organic solvent in presence of a basic catalyst. Examples of the basic catalyst include triethylamine, pyridine, 4-dimethylaminopyridine and the like. The compound represented by the above formula (12), the compound represented by the above formula (13) or the compound represented by the following formula (14), if necessary, and the above formula (A). The order in which the phenol compound is reacted is not particularly limited, and may be reacted simultaneously.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.
(Synthesis Example 1)
Synthesis of a compound represented by the following formula (4-vinyloxyethoxyphenyldiphenylsulfonium perfluorobutanesulfonate):

  After dissolving 1.55 g of diphosphorus pentoxide and 4.28 g of diphenyl sulfoxide in 20.3 g of methanesulfonic acid, 3.00 g of phenol was added and stirred at room temperature for 15 hours. 65 g of water was dropped while maintaining the temperature at 30 ° C. or lower, and the aqueous layer was washed 3 times with 22 g of t-butyl methyl ether. did. After stirring was stopped and the separated aqueous layer was removed, 22 g of a 0.1 wt% aqueous ammonia solution was added and stirred. Next, the organic layer was washed with pure water, and this was repeated until the pH of the separated aqueous layer reached 7. By distilling off the solvent with a rotary evaporator, 10.0 g of 4-hydroxyphenyldiphenylsulfonium perfluorobutanesulfonate was obtained.

Next, 10.0 g of 4-hydroxyphenyldiphenylsulfonium perfluorobutanesulfonate, 3.45 g of potassium carbonate, and 0.2 g of N, N, N ′, N′-tetramethylethylenediamine were dissolved in 50 g of dimethyl sulfoxide. Thereafter, 2.66 g of chloroethyl vinyl ether was added and the temperature was raised to 80 ° C. The mixture was stirred for 15 hours, and the reaction solution was cooled to 30 ° C or lower. After removing the solid content by filtration, 25 g of water was added to the filtrate. The aqueous layer was washed 3 times with 30 g of hexane, 40 g of dichloromethane and 50 g of water were added and stirred, and the target product was extracted into the dichloromethane layer. The organic layer was repeatedly washed with pure water until the pH of the separated aqueous layer reached 7. The solvent was distilled off with a rotary evaporator to obtain 9.00 g of an oily substance. This substance was confirmed to be 4-vinyloxyethoxyphenyldiphenylsulfonium perfluorobutanesulfonate from the results of measurement by ¹ H NMR and ion chromatography.
¹ H NMR (400 MHz, CDCl ₃ ) δ 4.05-4.08 (m, 3H), 4.24 (d, J = 7.4, 2.4 Hz, 1H), 4.31-4.33 (m , 2H), 6.49 (dd, J = 14.4, 7.4 Hz, 1H), 7.24 (d, J = 6.8 Hz, 2H), 7.64-7.74 (m, 12H)

(Synthesis Example 2)
Synthesis of a compound represented by the following formula (4-vinyloxyethoxy-3,5-dimethylphenyldi (4-t-butylphenyl) sulfonium cyclo (1,3-perfluoropropanedisulfone) imide salt):

  After dissolving 3.10 g of diphosphorus pentoxide and 13.3 g of bis (4-t-butylphenyl) sulfoxide in 40.5 g of methanesulfonic acid, 7.76 g of 2,6-xylenol was added and stirred at room temperature for 15 hours. . While maintaining a temperature of 30 ° C. or less, 130 g of water was added dropwise, and the aqueous layer was washed three times with 45 g of t-butyl methyl ether, and then 45 g of methyl isobutyl ketone and 15.4 g of cyclo1,3-perfluoropropane disulfonimide potassium salt. And stirred for 2 hours. After stirring was stopped and the separated aqueous layer was removed, 45 g of a 0.1 wt% aqueous ammonia solution was added and stirred. Next, the organic layer was washed with pure water, and this was repeated until the pH of the separated aqueous layer reached 7. By distilling off the solvent with a rotary evaporator, 23.2 g of 4-hydroxy-3,5-dimethylphenyldi (4-t-butylphenyl) sulfonium cyclo (1,3-perfluoropropanedisulfone) imide salt was obtained. .

This brown oily 4-hydroxy-3,5-dimethylphenyldi (4-t-butylphenyl) sulfonium cyclo (1,3-perfluoropropanedisulfone) imide salt 16.0 g, potassium carbonate 4.7 g and N, N , N ′, N′-tetramethylethylenediamine was dissolved in 80 g of dimethyl sulfoxide. Thereafter, 3.66 g of chloroethyl vinyl ether was added and the temperature was raised to 80 ° C. The mixture was stirred for 15 hours, and the reaction solution was cooled to 30 ° C or lower. After removing the solid content by filtration, 40 g of water was added, and the aqueous layer was washed 3 times with 30 g of hexane. 60 g of dichloromethane and 120 g of water were added and stirred, and the target product was extracted into the dichloromethane layer. The organic layer was repeatedly washed with pure water until the pH of the separated aqueous layer reached 7. The solvent was distilled off with a rotary evaporator to obtain 14.4 g of an oily substance. This substance was obtained from the measurement results by ¹ H NMR and ion chromatography, based on 4-vinyloxyethoxy-3,5-dimethylphenyldi (4-t-butylphenyl) sulfonium cyclo (1,3-perfluoropropanedisulfone) imide salt. It was confirmed that.
¹ H NMR (400 MHz, CDCl ₃ ) δ 1.35 (s, 18H), 2.36 (s, 6H), 4.02-4.08 (m, 3H), 4.12-4.14 (m, 2H), 4.25 (d, J = 14.3, 6.1 Hz, 1H), 6.50 (dd, J = 14.3, 6.6 Hz, 1H), 7.35 (s, 2H), 7.59-7.75 (m, 8H)

(Synthesis Example 3)
Synthesis of a compound represented by the following formula (4-vinyloxyoctoxyphenyldiphenylsulfonium bis (perfluoromethanesulfone) imide salt):

  After dissolving 1.55 g of diphosphorus pentoxide and 4.28 g of diphenyl sulfoxide in 20.3 g of methanesulfonic acid, 3.00 g of phenol was added and stirred at room temperature for 15 hours. 65 g of water was dropped while maintaining the temperature at 30 ° C. or lower, and after washing the aqueous layer 3 times with 22 g of t-butyl methyl ether, 22 g of methyl isobutyl ketone and 7.43 g of bis (perfluoromethanesulfone) imide potassium salt were added. And stirred for 2 hours. After stirring was stopped and the separated aqueous layer was removed, 22 g of a 0.1 wt% aqueous ammonia solution was added and stirred. Next, the organic layer was washed with pure water, and this was repeated until the pH of the separated aqueous layer reached 7. By distilling off the solvent with a rotary evaporator, 11.0 g of 4-hydroxyphenyldiphenylsulfonium bis (perfluoromethanesulfone) imide salt was obtained.

  Next, 1.23 g of 8-chloro-1-octanol, 0.47 g of sodium carbonate, 0.47 g of di-μ-chlorobis [η-cyclooctadieniridium (I)] and 1.31 g of vinyl acetate were added to 6.15 g of toluene. And stirred at 100 ° C. for 4 hours. After cooling to room temperature, the solvent was distilled off and purified by column chromatography using a mixed solvent of hexane and dichloromethane (volume ratio of hexane and dichloromethane is 2: 1) as a solvent to obtain 8 -1.16 g of chlorooctyl vinyl ether was obtained.

The resulting 4-hydroxyphenyldiphenylsulfonium bis (perfluoromethanesulfone) imide salt 2.60 g, potassium carbonate 0.78 g and N, N, N ′, N′-tetramethylethylenediamine 0.05 g were added to 13.3 g of dimethyl sulfoxide. Dissolved in. Thereafter, 1.05 g of 8-chlorooctyl vinyl ether was added and the temperature was raised to 80 ° C. The mixture was stirred for 15 hours, and the reaction solution was cooled to 30 ° C or lower. After removing the solid content by filtration, 13.3 g of water was added, and the aqueous layer was washed three times with 7.96 g of hexane. Dichloromethane (10.6 g) and water (10 g) were added and stirred, and the desired product was extracted into the dichloromethane layer. The organic layer was repeatedly washed with pure water until the pH of the separated aqueous layer reached 7. The solvent was distilled off with a rotary evaporator to obtain 2.53 g of a brown oily substance. This substance was confirmed to be 4-vinyloxyoctoxyphenyldiphenylsulfonium bis (perfluoromethanesulfone) imide salt from the measurement results by ¹ H NMR and ion chromatography.
¹ H NMR (400 MHz, CDCl ₃ ) δ 1.36-1.47 (m, 8H), 1.64-1.67 (m, 2H), 1.78-1.83 (m, 2H), 3. 67 (t, J = 6.6 Hz, 2H), 3.96 (dd, J = 6.8, 2.0 Hz, 1H), 4.04 (t, J = 6.6 Hz, 2H). 4.16 (dd, J = 14.4, 2.0 Hz, 1H), 6.46 (dd, J = 14.4, 6.8 Hz, 1H), 7.16-7.19 (m, 2H) , 7.65-7.76 (m, 12H)

  Example 1 Synthesis of a sulfonium salt represented by the following formula (15)

Under nitrogen atmosphere, 3.00 g of 2,3,4,4′-tetrahydroxybenzophenone represented by the above formula (a-15) and 4-vinyloxyethoxyphenyldiphenylsulfonium perfluorobutanesulfone obtained in Synthesis Example 1 The acid salt 8.22 g was dissolved in 60 g of propylene glycol monomethyl ether acetate and subjected to azeotropic dehydration. Next, 1.80 g of ethyl vinyl ether and 54 μL of trifluoroacetic acid were added, and the mixture was stirred at 30 ° C. for 18 hours. After the reaction, the reaction solution was neutralized with aqueous ammonia, and 30 g of ethyl acetate and 30 g of pure water were added to perform separation and washing with water. The same operation was performed 3 times, and the solvent was removed by distilling off the organic layer under reduced pressure. The concentrate was subjected to column purification with silica gel to obtain 10.8 g of a viscous compound. ^From the results of ¹ H-NMR, a sulfonium salt represented by the above formula (15) in which D ¹ and D ² are H and is any one of the groups represented by the above formula (16) or the above formula (17) is obtained. The acid generator group represented by the above formula (17) is 1.0 equivalent with respect to 2,3,4,4′-tetrahydroxybenzophenone, and the group represented by the above formula (16) is 1. It was confirmed to be 8 equivalents.

  (Example 2) Synthesis of a sulfonium salt represented by the following formula (18)

Under a nitrogen atmosphere, 2.30 g of 2,3,4-trihydroxybenzophenone represented by the above formula (a-14) and 4-vinyloxyethoxy-3,5-dimethylphenyldi (4- 10.2 g of t-butylphenyl) sulfonium cyclo (1,3-perfluoropropanedisulfone) imide salt was dissolved in 70 g of propylene glycol monomethyl ether acetate, and water in the system was reduced by azeotropic dehydration. Next, 70 μL of trifluoroacetic acid was added and stirred at 30 ° C. for 4 hours. After the reaction, 0.20 g of 4-dimethylaminopyridine was added, 3.36 g of di-t-butyl dicarbonate was added, and the mixture was stirred at 30 ° C. for 12 hours. To this reaction liquid, 35 g of dichloromethane and 35 g of pure water were added, followed by liquid separation and washing. The same operation was performed 3 times, and the solvent was removed by distilling off the organic layer under reduced pressure. The concentrate was subjected to column purification with silica gel to obtain 11.6 g of a viscous compound. ^From the result of ¹ H-NMR, D ¹ is H, the sulfonium salt represented by the above formula (18), which is any one of the group represented by the above formula (19) and the group represented by the above formula (20). The acid generator group represented by the above formula (20) is 1.1 equivalents relative to 2,3,4-trihydroxybenzophenone, and the group represented by the above formula (19) is 1.4. It was confirmed to be equivalent.

  Example 3 Synthesis of a sulfonium salt represented by the following formula (21)

Under a nitrogen atmosphere, 3.17 g of 2,3,4,2 ′, 4′-pentahydroxybenzophenone represented by the above formula (a-16) and 4-vinyloxyoctoxyphenyldiphenylsulfonium obtained in Synthesis Example 3 Bis (perfluoromethanesulfone) imide salt (17.3 g) was dissolved in propylene glycol monomethyl ether acetate (65 g) and subjected to azeotropic dehydration. Next, 70 μL of trifluoroacetic acid was added and stirred at 30 ° C. for 28 hours. After the reaction, the reaction solution was neutralized with aqueous ammonia, and 32 g of dichloromethane and 32 g of pure water were added to perform separation and water washing. The same operation was performed 3 times, and the solvent was removed by distilling off the organic layer under reduced pressure. The concentrate was subjected to column purification with silica gel to obtain 15.4 g of a viscous compound. ^From the result of ¹ H-NMR, a sulfonium salt represented by the above formula (21) in which D ¹ and D ² are H or a group represented by the above formula (22) is obtained. It was confirmed that the acid generator group represented by the above formula (22) was 1.8 equivalents relative to ', 4'-pentahydroxybenzophenone.

(Preparation and characterization of photoresist)
100 parts by weight of the sulfonium salt obtained in Examples 1 to 3 above and 3 parts by weight of triethanolamine were dissolved in 400 parts by weight of propylene glycol monomethyl acetate and filtered through a filter (PTFE filter). This solution was applied to a silicon wafer (diameter: 4 inches) using a spinner and prebaked at 120 ° C. for 90 seconds to obtain a resist film having a thickness of 300 nm. This film was exposed with a xenon lamp (wavelength: 248 nm) and then post-baked at 100 ° C. for 60 seconds. After that, using a developer (2.38 wt% tetramethylammonium hydroxide aqueous solution) at 23 ° C., breakthrough time (seconds in which there is no residual film by development after irradiation with a certain energy) Was measured.
As a result, the breakthrough times of the sulfonium salts obtained in Examples 1 to 3 were all 1 second or less at 100 mJ. From this, the photosensitive compounds obtained in Examples 1 to 3 generate an acid from the structural portion derived from the sulfonium salt of the present invention upon exposure with a xenon lamp, and this acid causes the formula (2 ), The group represented by formula (3), and the group represented by formula (4) were decomposed, and it was found that the group became difficult to soluble in the developer.

(Solubility in resist solvent)
The sulfonium salts of Examples 1 to 3 are characterized by having higher solubility in a resist solvent than conventional sulfonium salts because the group of formulas (3) and (4) can be arbitrarily introduced using a phenol compound as a base. Is mentioned. It was confirmed that the sulfonium salts of Examples 1 to 3 were dissolved in propylene glycol monomethyl ether acetate by 20% by weight or more.

Claims (5)

A sulfonium salt represented by the following formula (1):
In (Equation (1), ^{R 1} and ^{R 2} each independently represent a hydrogen atom, a methyl group, an isopropyl group, t- butyl group, a cyclohexyl group, or, .D ¹ representing a an alkoxy group having 1 to 12 carbon atoms And D ² are mutually independent, at least one is a group represented by the following formula (2), and the remainder is represented by a hydrogen atom, a group represented by the following formula (3) or the following formula (4). A, b, c, and d are integers of 0 or more that satisfy a + b ≦ 5, c + d ≦ 5, and a + c ≧ 1, respectively, and W represents C 2 O. )
(In Formula (2), R ³ is a linear or branched divalent alkylene group having 2 to 8 carbon atoms, R ^{4 to} R ⁷ are each independently a hydrogen atom or a methyl group , and R ⁸ and R ⁹ are each independently a phenyl group, methylphenyl group or t- butylphenyl group .X ^- represents an anion).
(In Formula (3), R ¹⁰ represents a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms or an optionally substituted aromatic group having 6 to 30 carbon atoms.)
Wherein X ^- anion represented by the sulfonium salt according to claim 1, characterized in that the anion of the following formula (5).
(In Formula (5), k, m, and n each independently represent an integer of 0 or more. When m is 0, k is an integer of 1 to 8, n is 2k + 1, and Formula (5) is A perfluoroalkylsulfonate ion, when n is 0, k is an integer of 1 to 15, m is an integer of 1 or more, and formula (5) is an alkylsulfonate ion, a benzenesulfonate ion, or an alkylbenzenesulfonate ion. When m and n are each independently an integer of 1 or more, k is an integer of 1 to 10, and the formula (5) is a fluorine-substituted benzenesulfonate ion, a fluorine-substituted alkylbenzenesulfonate ion, or a fluorine-substituted alkylsulfonate ion.) 2. The sulfonium salt according to claim 1, wherein the anion represented by X ⁻ is a bis (perfluoroalkylsulfone) imide ion represented by the following formula (6).
(In the formula, p represents an integer of 1 to 8.) 2. The sulfonium salt according to claim 1, wherein the anion represented by X ⁻ is an anion represented by the following formula (7).
2. The sulfonium salt according to claim 1, wherein the anion represented by X ⁻ is Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ or PF ₆ ^−. .