JP2008266495A - Photo acid-generating agent, production method thereof and resin composition for photo lithography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo acid-generating agent and the like, corresponding to non-ionic i line (UV), excellent in solubility to resins, and easily producible. <P>SOLUTION: The photo acid-generating agent is represented by formula (I) (wherein, x is an integer of 1-8; and y is an integer of 3-17). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition for photolithography used for semiconductor production and the like, and a photoacid generator (PAG) that is a component thereof, in particular, a photoacid generator that generates acid when irradiated with ultraviolet rays (i-line), The present invention relates to a production intermediate thereof, a method for producing the photoacid generator, and a resin composition for photolithography containing the photoacid generator.

  Nonionic i-line-compatible photoacid generators are attracting attention because they are relatively compatible with resins and can be used with high-pressure mercury lamps that are inexpensive light sources (for example, Non-Patent Document 1 to Non-Patent Document 1). Reference 5).

  Accordingly, the inventors have developed an imide-type photoacid generator N-trifluoromethanesulfonyloxy-7-methylthianthrene-2,3-dicarboxylic acid imide (hereinafter referred to as Me-THITf) having a thianthrene having an absorption at 290 nm as a chromophore. And N-pentafluorobenzenesulfonyloxy-7-methylthianthrene-2,3-dicarboxylic imide (hereinafter abbreviated as Me-THIPS) have been developed (Non-Patent Document 5). See).

Me-THITf and Me-THIPS generate trifluoromethanesulfonic acid, which is a super strong acid when irradiated with light, and catalyze the crosslinking and insolubilization of the resin. The molar absorption coefficient at these i-line (wavelength 365 nm) is located respectively 1570M ^-1 cm ^-1 and 1640M ^-1 cm ^-1, which is commercially available products of the photoacid generator N- trifluoromethane sulfonyl b carboxymethyl -1 , 8-naphthylimide (hereinafter abbreviated as NITf).

  By the way, these Me-THITf and Me-THIPS were synthesized as shown in FIG. First, 4,5-dichlorophthalic anhydride (hereinafter abbreviated as Compound 1) is passed through N-phenyl-4,5-dichlorophenylimide (hereinafter abbreviated as Compound 10), which is a protective process. , 4-methylbenzene-1,2-dithiol (hereinafter abbreviated as Compound 11), and N-phenyl-7-methylthianthrene-2,3-dicarboxylic acid imide having a thianthrene skeleton (hereinafter referred to as Compound) Abbreviated as 12).

Next, 7-methylthianthrene-2,3-dicarboxylic acid (hereinafter abbreviated as compound 13) and 7-methythanthrene-2,3-dicarboxylic acid anhydride (hereinafter abbreviated as compound 14) which are deprotection processes. N-hydroxy-7-methylthianthrene-2,3-dicarbonimide (hereinafter abbreviated as compound 6) was synthesized. Finally, Me-THIPS (15a) and Me-THITf (15b) were synthesized from this compound 6.
T. Asakura, H. Yamato, M. Ohwa, J. Photopolym. Sci. Technol., 13, 223 (2000). H. Okamura, Y. Watanabe, M. Tsunooka, M. Shirai, T. Fujiki, S. Kawasaki, M. Yamada, J. Photopolym. Sci. Technol., 15, 145 (2002). H. Okamura, K. Sakai, M. Tsunooka, M. Shirai, J. Photopolym. Sci. Technol., 16, 87 (2003). C. Iwashima, G. Imai, H. Okamura, M. Tsunooka, M. Shirai, J. Photopolym. Sci. Technol., 16, 91 (2003). H. Okamura, R. Matsumori, M. Shirai, J. Photopolym. Sci. Technol., 17,131, (2004).

  However, although Me-THITf and Me-THIPS are excellent photoacid generators, the solubility in a solvent is not so good and the compatibility with the resin is also insufficient. In addition, synthesis of these photoacid generators requires a process of protection and deprotection, so it takes a lot of labor and a long reaction time to reach the final products, Me-THITf and Me-THIPS. It took time.

  As a result of intensive studies on the structure of the photoacid generator, the inventors have improved the solubility of the photoacid generator in a solvent by introducing a tert-butyl group instead of a methyl group into the thianthrene skeleton. Successful. In addition, the production time of the photoacid generator could be shortened by introducing a process for producing an intermediate without requiring a protection / deprotection process.

（式中、xは1から8の整数、yは3から17の整数である。）
で示すものである。 That is, the photoacid generator according to claim 1 is:
Formula (I)

(In the formula, x is an integer from 1 to 8, and y is an integer from 3 to 17.)
It is shown by.

The photoacid generator according to claim 2 is the photoacid generator according to claim 1, wherein C _x F _{y in the} formula (I) is CF ₃ .

The photoacid generator according to claim 3 is the photoacid generator according to claim 1, wherein C _x F _{y in} formula (I) is C ₆ F ₅ .

で示す化合物であり、請求項１の光酸発生剤の製造中間体である。 The N-hydroxy-7-tert-butylthianthrene-2,3-dicarboxylic imide according to claim 4 has the formula (II)

It is a compound shown by these, and is a manufacturing intermediate of the photo-acid generator of Claim 1.

で示す化合物であり、請求項１の光酸発生剤の製造中間体である。 7-tert-butylthianthrene-2,3-dicarboxylic imide according to claim 5 is
Formula (III)

It is a compound shown by these, and is a manufacturing intermediate of the photo-acid generator of Claim 1.

  The method for producing a photoacid generator according to claim 6 is the method for producing a photoacid generator according to claim 1, wherein the base, N, N-dimethylformamide, and toluene are added under an inert gas atmosphere. In the presence, 7,5-dichlorophthalimide and 4-tert-butylbenzene-1,2-dithiol are reacted under heating to produce 7-tert-butylthianthrene-2,3-dicarboxylic imide. Process. Examples of the inert gas include chemically inert nitrogen gas and rare gas, but nitrogen gas is preferable from the viewpoint of cost. Examples of the base include sodium hydroxide, potassium hydroxide, and lithium hydroxide, and sodium hydroxide and potassium hydroxide are preferable from the viewpoint of cost.

  The resin composition for photolithography according to claim 7 includes the photoacid generator according to any one of claims 1 to 3.

  This resin composition for photolithography contains, in addition to a photoacid generator, a resin that is cross-linked and insolubilized by an acid generated from the photoacid generator, and, if necessary, a solvent for improving known coating properties. In addition, various additives may be included.

  Examples of the resin include polymers, oligomers, and polyfunctional monomers having an epoxy group, an oxetane group, and a vinyl ether group in the side chain. Among these, an oligomer having an epoxy group is preferable from the viewpoint of high reactivity, versatility, and properties of a cured product. In addition, you may use these resin individually or in combination of 2 or more types.

  Examples of the solvent include organic solvents such as N, N′-dimethylformamide, tetrahydrofuran, toluene, dimethoxyethane, acetonitrile, diethylene glycol dimethyl ether, cyclohexanone, and propylene glycol methyl ether acetate. Among these, cyclohexanone is preferable because of its high solubility in the compound and its appropriate boiling point. In addition, you may use these solvents individually or in combination of 2 or more types.

  Examples of the additive include dyes, pigments, thickeners, antifoaming agents, leveling agents, and dispersing agents.

  The photoacid generators according to claims 1 to 3 have higher solubility in a solvent than conventional photoacid generators. Therefore, compatibility with the resin is also increased, and a more uniform photolithography composition can be obtained.

  By using the compounds of Claims 4 and 5, or by using the production method of Claim 6, the production time of the photoacid generator can be shortened.

  With the resin composition for photolithography according to the seventh aspect, a resin layer (film) having a uniform thickness can be easily manufactured on a Si substrate or the like.

  The present invention will be described below with reference to examples. However, the scope of the claims of the present invention is not limited in any way by the following examples.

1. Synthesis and Evaluation of Photoacid Generator According to the synthesis route shown in FIG. 1, two types of thianthrene imide sulfonates having a tert-butyl group were synthesized and their physical properties were evaluated. The details will be described below. In addition, in order to clarify the relationship between FIG. 1 and the following description, the same number was given to the same compound.

(1) Reagent
4,5-dichlorophthalic anhydride (hereinafter abbreviated as Compound 1) was purchased from Tokyo Chemical Industry. Further, disulfur dichloride, dicarbon di-tert-butyl (hereinafter abbreviated as (Boc) ₂ O), and a 50% hydroxylamine solution purchased from Wako Pure Chemicals were used as they were. tert-Butylbenzene (hereinafter abbreviated as Compound 3), tert-butoxypotassium (hereinafter abbreviated as t-BuOK) 1.0M THF solution, pentafluorobenzenesulfonyl chloride, trifluoromethanesulfonyl chloride were purchased from Aldrich. The thing was used as it was. Zinc purchased from Kishida Chemical was used as it was. N, N-dimethylaminopyridine (hereinafter abbreviated as DMAP) and formamide purchased from Nacalai Tesque were used as they were. Tetrahydrofuran (hereinafter abbreviated as THF), N, N′-dimethylformamide (hereinafter abbreviated as DMF), toluene, dimethoxyethane (hereinafter abbreviated as DME), acetonitrile, diethylene glycol dimethyl ether, and cyclohexanone are: Distilled with CaH ₂ was used. NITf, Me-THITf, and Me-THIPS were synthesized according to Non-Patent Document 5.

(2) Measuring device
¹ H NMR spectrum was measured with an FT-NMR spectrometer (JEOL, GX-270). The IR spectrum was measured with an FT-IR spectrometer (JASCO, FT / IR-410). Mass spectrometry was performed with a mass spectrometer (GCMS QP2010plus, manufactured by Shimadzu Corporation). The UV-Vis spectrum was measured with a UV-Vis spectrometer (Shimadzu Corporation, UV2400PC). The decomposition point (T _d ) was measured with a thermogravimetric analyzer (Shimadzu Corporation, TGA-50).

(3) Synthesis of photoacid generator (a) Synthesis of 4,5-dichlorophthalimide Synthesized according to the literature (K. Kacprzak, Synth. Commun., 33 (9), 1499 (2003)). First, formamide (12.0 g, 266 mmol) was placed in a four-necked flask, and compound 1 (3.00 g, 13.8 mmol) was slowly added over 5 minutes while stirring. Next, the flask was immersed in an oil bath, slowly heated over 35 minutes, and reacted at 130 ° C. for 2 hours. Thereafter, the temperature was lowered to 120 ° C., the contents of the flask were poured into 300 ml of ice water, the precipitated solid was filtered off, and the solid was washed with water. Finally, the washed solid was vacuum-dried to obtain pale yellow 4,5-dichlorophthalimide (hereinafter abbreviated as Compound 2) (2.60 g, yield 87%). In addition, this compound 2 was identified from the analysis result shown below.

mp: 215-216 ° C (literature value: 218-220 ° C, according to the above literature); IR (KBr) 3468cm ^-1 (NH); Anal. Calcd for C ₈ H ₃ Cl ₂ NO ₂ : C, 44.48; H , 1.40; N, 6.48. Found: C, 44.76; H, 1.37; N, 6.24.

(B) Synthesis of 4-tert-butylbenzene-1,2-dithiol It was synthesized according to Japanese Patent Application Laid-Open No. 07-173130. First, Compound 3 (91.0 g, 679 mmol), iodine (107 g, 423 mmol), disulfur dichloride (135 g, 1000 mmol), and 257 ml of chloroform were placed in a four-necked flask and reacted at 42 ° C. for 24 hours. Next, the reaction system was returned to room temperature, zinc (164 g, 2.51 mol) and 780 ml of 35% HCl were added, and the mixture was reacted for 2 hours while refluxing at 60 ° C.

Furthermore, the reaction system was returned to room temperature, the product was extracted four times with 500 ml of chloroform, the organic phase was dried over anhydrous MgSO ₄ , and then the solvent was distilled off. Finally, the residue was distilled under reduced pressure (1 mmHg, 110 ° C.) to obtain liquid 4-tert-butylbenzene-1,2-dithiol (hereinafter abbreviated as compound 4) (17.2 g). Yield 12%). In addition, this compound 4 was identified from the analysis result shown below.

¹ H NMR (CDCl ₃ ): δ 7.35 (1H, s, aromatic), 7.25 (1H, d, aromatic), 7.05 (1H, d, aromatic), 3.72 (1H, s, SH), 3.54 (1H, s , SH), 1.21 (9H, s, -C (CH ₃ ) ₃ ).

(C) Synthesis of 7-tert-butylthianthrene-2,3-dicarboxylic imide First, in nitrogen, compound 4 (0.500 g, 2.52 mmol), KOH (0.480 g, 8.58 mmol), DMF (12.0 ml) and After putting the mixed solution of toluene (5.00 ml) into the flask and assembling the Dean Stark apparatus, the contents of the flask are reacted by stirring at 130 ° C. for 18 hours, and toluene and water are discharged from the reaction system. While refluxing.

Next, the reaction system was cooled to 60 ° C., Compound 2 (1.00 g, 4.65 mmol) was added, and the mixture was stirred at 90 ° C. for 18 hours. After completion of the reaction, the reaction system was returned to room temperature and extracted four times with 100 ml of chloroform. The organic layer was dried over anhydrous MgSO ₄ and then the solvent was distilled off.

  Finally, the solid obtained by drying was purified by a medium pressure column using a mixed solvent of ethyl acetate: chloroform = 1: 2 as an eluent. As a result, 7-tert-butylthianthrene-2,3-dicarboxylic imide (hereinafter abbreviated as compound 5) was obtained as a yellow solid (0.920 g, yield 58%). In addition, this compound 5 was identified from the analysis result shown below.

mp: 221-223 ° C; ¹ H NMR (CDCl ₃ ): δ 7.88 (2H, d, aromatic), 7.48 (1H, d, aromatic), 7.39 (1H, s, aromatic), 7.32 (1H, d, aromatic ), 1.28 (9H, s, -C (CH ₃ ) ₃ ); IR (KBr) 3257 (NH), 1714 cm ^-1 (C = O); MS (EI), m / z 341 (M ⁺ , 100 Anal.Calcd for C ₁₈ H ₁₅ NO ₂ S ₂ : C, 63.32; H, 4.43; N, 4.10. Found: C, 63.35; H, 4.16; N, 3.64.

(D) Synthesis of N-hydroxyl-7-tert-butylthianthrene-2,3-dicarboxylic imide Literature (C. Einhorn, J. Einhorn, C. Marcadal-Abbadi, Synth. Commun., 31 (5), 741 (2001).). First, DMAP (38.0 g) dissolved in acetonitrile (4.00 ml) in a mixed solution of compound 5 (3.80 g, 11.0 mmol), acetonitrile (5.00 ml) and (Boc) ₂ O (3.00 ml, 13.3 mmol) in nitrogen. mg, 22.9 mmol) was added, and the mixture was stirred at room temperature for 2 hours.

Next, 50 wt% NH ₂ OH (1.60 ml, 26.4 mmol) was added, and the mixture was stirred at room temperature for 18 hours. When the reaction was completed, the product was added dropwise to diethyl ether (15.0 ml) to precipitate a solid. The precipitated solid was filtered off and washed with a small amount of diethyl ether.

  After the obtained solid was vacuum-dried, the dried solid was put into 15 ml of water, and 1M HCl aq was slowly added to pH 1 with stirring. The solid was filtered off, and the filtered solid was washed with a small amount of water and then vacuum dried. As a result, N-hydroxyl-7-tert-butylthianthrene-2,3-dicarboxylic imide (hereinafter abbreviated as compound 6) was obtained as an orange solid (3.28 g, yield 83%). . In addition, this compound 6 was identified from the analysis result shown below.

mp: 108-110 ° C; ¹ H NMR (CDCl ₃ ): δ 7.95 (2H, d, aromatic), 7.44 (1H, d, aromatic), 7.33 (1H, s, aromatic), 7.30 (1H, d, aromatic ), 1.24 (9H, s, -C (CH ₃ ) ₃ ); IR (KBr) 3433 (N-OH), 1681 cm ^-1 (C = O); MS (EI), m / z 357 (M ⁺ , 96), 342 (M ⁺ -15, 100); Anal.Calcd for C ₁₈ H ₁₅ NO ₃ S ₂ : C, 60.48; H, 4.23; N, 3.92. Found: C, 60.40; H, 4.25; N , 3.63

(E) Synthesis of N-trifluoromethanesulfonyloxy-7-tert-butylthianthrene-2,3-dicarboxylic acid imide (tert-THITf) First, distilled nitrogen (30.0 ml) and t-BuOK (0.160 g, 1.40 mmol) were added to compound 6 (0.500 g, 1.40 mmol) placed in a flask in nitrogen, and the mixture was stirred at room temperature for 30 minutes. Thereafter, THF was distilled off, and the mixture was once again put into nitrogen. DME (10.0 ml) was added, and the mixture was heated to −78 ° C. in a cooling thermostat while stirring.

CF ₃ SO ₂ Cl (0.150 ml, 1.40 mmol) was added thereto, and the mixture was stirred at −20 ° C. for 1 hour. After the reaction was completed, DME was distilled off from the reaction system to obtain a viscous solid. The viscous solid obtained by drying was purified by a medium pressure column using toluene as an eluent, and then the toluene was distilled off and dried to obtain a viscous solid. Further, this viscous solid was purified again by a preparative column using chloroform as an eluent, and then chloroform was distilled off and vacuum-dried. As a result, N-trifluoromethanesulfonyl-7-tert-butylthianthrene-2,3-dicarboxylic imide (hereinafter, compound 7a) was obtained as a yellow viscous solid (0.0740 g, yield 11%). In addition, this compound 7a was identified from the analysis result shown below.

¹ H NMR (CDCl ₃ ): δ 7.85 (2H, d, aromatic), 7.47 (1H, d, aromatic), 7.37 (1H, s, aromatic), 7.30 (1H, d, aromatic), 1.28 (9H, s , -C (CH ₃ ) ₃ ); IR (KBr) 1784 (C = O), 1381 (S (= O) ₂ ), 1192 cm ^-1 (-CF ₃ ); UV (acetonitrile) _max = 289 nm, logε = 3.27 (l / mol ・ cm); T _d : 156 ℃

(F) Synthesis of N-pentafluorobenzenesulfonyloxy-7-tert-butylthianthrene-2,3-dicarboxylic imide (tert-THIPS) The compound was synthesized according to Non-Patent Document 5. First, distilled nitrogen (30.0 ml) and tert-BuOK (0.314 g, 2.80 mmol) were added to compound 6 (1.00 g, 2.80 mmol) placed in a flask in nitrogen, and the mixture was stirred at room temperature for 30 minutes. Thereafter, THF was distilled off, and the mixture was once again put into nitrogen. DME (10.0 ml) was added, and the mixture was heated to −78 ° C. in a cooling thermostat while stirring.

C ₆ F ₅ SO ₂ Cl (0.430 ml, 2.80 mmol) was added thereto, and the mixture was stirred at −20 ° C. for 1 hour. After the reaction was completed, DME in the reaction system was distilled off to obtain a viscous solid. The viscous solid obtained by drying was purified by a medium pressure column using toluene as an eluent, and then the toluene was distilled off and dried to obtain a viscous solid. Furthermore, this viscous solid was recrystallized with toluene / hexane (1/10 v / v) and then vacuum-dried. As a result, a yellow viscous solid N-pentafluorobenzenesulfonyloxy-7-tert-butylthianthrene-2,3-dicarboxylic acid imide (hereinafter, compound 7b) was obtained (1.30 g, yield 78%). In addition, this compound 7b was identified from the analysis result shown below.

¹ H NMR (CDCl ₃ ): δ 7.83 (2H, d, aromatic), 7.41 (1H, d, aromatic), 7.31 (1H, s, aromatic), 7.29 (1H, d, aromatic), 1.23 (9H, s , -C (CH ₃ ) ₃ ); IR (KBr) 1773 (C = O), 1507 (CF), 1316 cm ^-1 (S (= O) ₂ ); UV (acetonitrile) λ _max = 289 nm, logε = 3.17 (l / mol ・ cm) .T _d : 206 ° C.

  Thus, since the synthesis route of the photoacid generator shown in FIG. 1 does not involve a protection / deprotection process, the reaction stage can be shortened by two stages, and the reaction time until reaching the final product is greatly increased. I was able to shorten it. On the other hand, regarding the overall yield, there was no significant difference compared with the conventional production method. However, an improvement in yield can be expected by optimizing the reaction for forming the thianthrene skeleton and the reaction for conversion to hydroxyimide.

(4) Physical properties of photoacid generator (a) Measurement of UV-Vis spectrum UV-Vis spectrum was measured in acetonitrile of synthesized tert-THITf and tert-THIPS. The result is shown in FIG. From the UV-Vis spectrum of FIG. 2, it was confirmed that the two kinds of synthesized photoacid generators had absorption at i-line (365 nm). The measured concentration of tert-THITf was 2.16 × 10 ⁻⁵ M, and the concentration of tert-THIPS was 2.22 × 10 ⁻⁵ M.

(B) Measurement of molar extinction coefficient and decomposition point Next, the molar extinction coefficient (ε) and decomposition point (T _d ) of tert-THITf and tert-THIPS were measured. The results are shown in Table 1. For comparison, the molar extinction coefficient (ε) and decomposition point (T _d ) of Me-THITf, Me-THIPS, and NITf are also shown.

As shown in Table 1, the molar extinction coefficients of tert-THITf and tert-THIP are 1950 and 1480M ^-1 cm ^-1 respectively, which is not much different from Me-THITf and Me-THIPS. It was greater than the molar extinction coefficient (330M ^-1 cm ^-1 ) of some NITf. This suggests that tert-THITf and tert-THIP may decompose more efficiently than NITf at 365 nm.

Regarding _Td , when the same substituents were compared, the order was Me-THIPS> Me-THITf and tert-THIPS> tert-THITf. From this result, it was found that _Td and the structure of the sulfonic acid ester site are greatly related. Considering the structure of the sulfonic acid ester moiety, it is considered that _Td decreases as the electron withdrawing property of the substituent on S increases. From this, it is considered that the stability of the NO bond derived from the electron withdrawing property of the substituent on S contributes to _Td .

In general, it is known that _Td, that is, the lower the thermal stability, the higher the photoreactivity. Therefore, it can be expected that tert-THITf is more reactive among the two photoacid generators synthesized this time. Since these photoacid generators have _Td of 156 ° C. and 206 ° C., it can be said that they are theoretically stable in the use temperature range as the photoacid generator.

(5) Solubility About 1 mg of photoacid generator was placed in a test tube, and about 0.1 ml of organic solvent was added in a room adjusted to 20 ° C. until the photoacid generator was completely dissolved. When 3 ml was not completely dissolved, it was evaluated as not dissolved. For comparison, the solubility of Me-THIPS and Me-THITf having a methyl group was also examined in the same manner. The results are shown in Table 2.

  As is apparent from Table 2, by introducing a tert-butyl group instead of a methyl group, an organic solvent having low solubility in Me-THIPS and Me-THITf having a methyl group, specifically, hexane, diethyl It became soluble in ether, ethanol and methanol. This indicates that the introduction of tert-butyl group significantly improved the solubility in organic solvents. In general, the improvement in solubility in an organic solvent corresponds to the improvement in solubility in a resin, so that an improvement in compatibility with the monomer, prepolymer and resin of the photoacid generator can be expected. In tert-THIPS and tert-THITf, a difference in solubility was observed only in methanol, but the cause is unknown.

(6) Change in absorption spectrum due to photolysis Generally, a photodegradable compound is decomposed by absorbing light, causing a change in absorbance of the UV-Vis spectrum. Therefore, tert-THITf and tert-THIPS were irradiated with light having a wavelength of 365 nm in acetonitrile to cause photolysis, and the change in the UV-Vis spectrum was measured. The result is shown in FIG. The measured concentration of tert-THITf was 2.32 × 10 ⁻⁵ M, and the concentration of tert-THIPS was 7.38 × 10 ⁻⁵ M.

  As is apparent from FIG. 3, it was found that the absorption around 265 nm increased with light irradiation, while the absorption around 290 and 310 nm decreased while tert-THITf and tert-THIPS increased. It was found that both of these absorbed 365nm light and caused photolysis.

  Next, in order to investigate the effect of the introduction of tert-butyl group on the photodegradation rate, tert-THITf, Me-THITf, tert-THIPS, Me-THIPS were irradiated with light at a wavelength of 365 nm and photolyzed, The change of the nearby peak was compared. The results of standardizing and comparing the absorbance are shown in FIGS.

As is clear from FIG. 4, there was no significant difference in the decomposition rate of Me-THITf and tert-THITf in the light irradiation up to 2000 mJ / cm ² from the change in normalized peak heights. However, when the irradiation light quantity was further increased, a difference in decomposition rate that was probably caused by a side reaction was recognized.

  Further, as apparent from FIG. 5, even when the irradiation light quantity was increased, no significant difference was observed in the decomposition rate of Me-THIPS and tert-THIPS.

  As described in Non-Patent Document 5, it is already known that Me-THITf has a higher decomposition rate than Me-THIPS. Further, from the above results, it was found that there was no significant difference in the decomposition rate between tert-THITf and Me-THITf and the decomposition rate between tert-THIPS and Me-THIPS, particularly when a large amount of light was not irradiated. Considering these facts, tert-THITf is expected to have a faster decomposition rate than tert-THIPS.

2. Production of Film and Its Evaluation A resin composition for photolithography containing the photoacid generator synthesized in Example 1 was prepared, and this was photopolymerized to produce a film, and the properties of this film were evaluated. In addition, polyglycidyl methacrylate (PGMA) was used for the resin component of the resin composition for photolithography.

(1) Reagent Glycidyl methacrylate (GMA) used was distilled from Tokyo Kasei. 2,2′-Azobisisobutyronitrile (AIBN) was purchased from Nacalai Tesque and recrystallized (solvent: chloroform). Further, NITf, Me-THITf, and Me-THIPS were synthesized according to Non-Patent Document 5 as in Example 1.

(2) Measuring equipment, etc.
M _n and M _w of PGMA the pump (JASCO, 880-PU), a detector (JASCO, RI-1530,870-UV ), degasser (JASCO, DG-980-53), a thermostat (chromatographic Science, CS -600H) and a column (TOSOH, GMH _HR -N, GMH _HR -H) were used, and measurement was performed by the GCP method. Note that THF was used as the eluent, and the flow rate was set to 0.8 ml / min. Polystyrene (Tosoh) was used as the molecular weight standard substance.

  Photocuring was performed by extracting only 365 nm light from the light generated by a high-pressure mercury lamp (USHIO, UM-102) and irradiating it with an interference filter (Asahi Spectrometer, MZ0365).

Furthermore, a spin coater (Mikasa spin coater, 1H-D ₃ type) was used for film production. Furthermore, the film thickness on the Si plate was measured with a film thickness measuring instrument (Nanometrics Japan, Nanospec M3000). The light intensity was measured with an ultraviolet illuminometer (Oak Seisakusho, UV-MO2).

(3) Production of film (a) Synthesis of polyglycidyl methacrylate (PGMA) First, a mixture of GMA (4.26 g, 33.2 mmol), AIBN (122 mg, 0.743 mmol), isopropylbenzene (11.5 ml), DMF (10.5 ml) Then, after bubbling with argon and replacing with argon, polymerization was carried out at 60 ° C. for 2 hours. Next, the reaction solution was added dropwise to MeOH, and the resulting precipitate was filtered off. Finally, reprecipitation purification was performed three times in a THF / MeOH system. As a result, white powder (1.21 g, 28%) was obtained. It was confirmed by ¹ H NMR that no monomer remained. Moreover, the molecular weight converted into polystyrene calculated | required by GPC method was _Mn = 28800, _Mw = 56400, _Mw / _Mn = 1.69.

(B) Preparation of PGMA film First, about 1 mol% of each photoacid generator (tert-THITf: 0.688 mg, tert-THIPS: 0.828 mg, Me-THITf: 0.629 mg, Me-) with respect to PGMA (20.0 mg). (THIPS: 0.767 mg, NITf: 0.480 mg) was added, and this was dissolved in 233 mg of cyclohexanone and applied onto a Si plate by a spin coater. Next, pre-baking was performed at 80 ° C. for 5 minutes in order to remove the residual solvent. As a result, a film having a thickness of about 0.3 μm was obtained.

(4) Measurement of insolubilization rate The prepared film was irradiated with light having a wavelength of 365 nm with a different irradiation light amount, then immersed in THF for 10 minutes, and the insolubilization rate was determined from the film thickness ratio before and after immersion. The result is shown in FIG. FIG. 7 shows a mechanism in which an acid is generated from the photoacid generator by light irradiation, and the epoxy group of the PGMA side chain is crosslinked and insolubilized by this acid.

  As is clear from FIG. 6, when comparing the acid catalytic ability of tert-THITf, tert-THIPS, Me-THITf, Me-THIPS, and NITf in terms of insolubilization of PGMA, the four photoacid generators having a thianthrene skeleton were compared. There was no big difference between them. However, comparing these four photoacid generators with NITf, it was found that the photoacid generator having a thianthrene skeleton is efficient.

In general, it is known that the insolubilization rate of the PGMA film by the photoacid generator depends on the quantum yield of acid generation and the strength of the acid generated. In addition, the quantum yield in the PGMA film was not quantified this time. However, when the quantum yield was quantified in the polymethacrylonitrile film, Φ _a (0.036) of Me-THITf was about three times larger than Φ _a (0.013) of Me-THIPS. 5. Furthermore, it is generally known that CF ₃ SO ₃ H generated from Me-THITf is a stronger acid than C ₆ F ₅ SO ₃ H generated from Me-THIPS.

  Considering these points, the insolubilization rate of PGMA should show a clear difference depending on the photoacid generator. However, from the results for the four photoacid generators having the thianthrene skeleton, it was not recognized that the insolubilization rate was dependent on the quantum yield of acid generation and the strength of the acid generated.

  This is probably because even when a large amount of strong acid was generated, the crosslinking reaction rate was slow at room temperature and was not reflected in the insolubilization rate of the PGMA film in the time scale of this measurement. The reason why the crosslinking reaction rate is slow at room temperature is that the segmental motion of the PGMA side chain is insufficient and the acid diffusion and crosslinking reaction are limited.

It is a figure which shows the synthetic pathway of the manufacturing method of the photo-acid generator of this invention. It is a figure which shows the result of having measured the UV-Vis spectrum of tert-THITf and tert-THIPS in acetonitrile. It is a figure which shows the result of having irradiated the light of wavelength 365nm to tert-THITf and tert-THIPS in acetonitrile, and measuring the change of the UV-Vis spectrum. It is a figure which shows the result of having measured and standardized the change of the peak of around 310 nm by irradiating tert-THITf and Me-THITf with light having a wavelength of 365 nm to cause photolysis. It is a figure which shows the result of having measured and standardized the change of the peak around 310 nm by irradiating tert-THIPS and Me-THIPS with light with a wavelength of 365 nm to cause photolysis. It is a figure which shows the result of having produced the film from the resin composition for photolithography containing a different photo-acid generator, and having investigated the difference in the insolubilization rate. It is a figure which shows the mechanism in which the epoxy group of a PGMA side chain bridge | crosslinks and insolubilizes. It is a figure which shows the synthetic pathway of the manufacturing method of the conventional photo-acid generator.

Claims (7)

Formula (I)

(In the formula, x is an integer from 1 to 8, and y is an integer from 3 to 17.)
A photoacid generator represented by The photoacid generator according to claim 1, wherein C _x F _y in formula (I) is CF ₃ . The photoacid generator according to claim 1, wherein C _x F _y in formula (I) is C ₆ F ₅ . Formula (II)

N-hydroxy-7-tert-butylthianthrene-2,3-dicarboxylic imide represented by Formula (III)

7-tert-butylthianthrene-2,3-dicarboxylic acid imide represented by A method for producing a photoacid generator according to claim 1,
In an inert gas atmosphere, 4,5-dichlorophthalimide is reacted with 4-tert-butylbenzene-1,2-dithiol in the presence of a base, N, N-dimethylformamide, and toluene in a heated state. A process for producing a 7-tert-butylthianthrene-2,3-dicarboxylic acid imide.   A resin composition for photolithography, comprising the photoacid generator according to any one of claims 1 to 3.

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