JPH07252214A - Sulfonium salt and resist material - Google Patents

Abstract

PURPOSE:To obtain a new sulfonium salt highly sensitive to high energy rays, e.g. far ultraviolet rays, electron rays and X-rays, capable of forming patterns by developing with an alkali aqueous solution and useful as a component of a chemically amplifiable positive-type resist material suitable for a fine- processing technology. CONSTITUTION:This is a sulfonium salt expressed by formula I(R<1> to R<3> are each a substituted or an unsubstituted aromatic group, at least one of R<1> to R<3> is a substituted aromatic group having an acid-unstable group and at least one of the rest of groups is a nitrogen-containing aromatic group or all of R<1> to R<3> are nitrogen-containing aromatic groups), e.g. trlfluolomethanesulfonic acid bis(p-t-butoxyphenyl) (p-dimethylaminophenyl)sulfonium. A sulfonium salt of formula I is obtained by reacting a sulfoxide compound of formula III with trimethylsilyl triflate and subsequently reacting the reaction product with an aryl Grignard reagent of formula IV (X is a halogen). A chemically amplifiable positive-type resist material is obtained from an organic solvent, an alkali- soluble resin, a solution-inhibiting agent having an acid-unstable group and a sulfonium salt of formula I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to deep ultraviolet rays, electron beams, X-rays.
It has high sensitivity to high energy rays such as rays, and can be patterned by developing with an alkaline aqueous solution.
The present invention relates to a novel sulfonium salt suitable as a component of a chemically amplified positive resist composition suitable for microfabrication technology and a chemically amplified positive resist composition containing the sulfonium salt.

[0002]

2. Description of the Related Art LSI to be Solved
Along with the higher integration and higher speed of photolithography, there is a demand for finer pattern rules, and with optical exposure, which is currently used as a general-purpose technology, we are approaching the essential resolution limit derived from the wavelength of the light source. is there. In photoexposure using a g-line (436 nm) or an i-line (365 nm) as a light source, the pattern rule of about 0.5 μm is the limit, and the integration degree of the LSI manufactured using this is 16 Mbit DR.
Up to the AM equivalent. However, the trial manufacture of the LSI has already reached this stage, and the development of further miniaturization technology is urgently needed.

Due to such a background, deep-UV lithography is considered promising as a next-generation microfabrication technique. This deep UV lithography is 0.3-0.4μ
It is also possible to process m, and when a resist having a low light absorption is used, it is possible to form a pattern having a side wall that is nearly vertical to the substrate. In recent years, a technique using a high-intensity KrF excimer laser as a light source for far-ultraviolet rays has attracted attention, and a resist material having low light absorption and high sensitivity is required for use as a mass production technique.

Recently developed acid-catalyzed chemically amplified positive resist materials (Japanese Patent Publication No. 27660/1990).
JP-A-3-27829) is a resist material which is particularly promising for deep-UV lithography because it has high sensitivity, resolution and dry etching resistance and has excellent characteristics.

However, the conventional chemically amplified positive resist is exposed to PEB (Post Exposure) when exposed to deep ultraviolet rays, electron beams and X-ray lithography.
When the standing time before Bake) becomes long, the line pattern becomes T-top shape when the pattern is formed, that is, the upper part of the pattern becomes thick [PED (Po
st Exposure Deley)], which is considered to be because the solubility of the resist surface is lowered, which is a major drawback in practical use. Therefore, it is difficult to control the dimensions in the lithography process,
This also impairs dimensional controllability when processing a substrate using dry etching [Reference: W. Hinsberg,
et al. J. Photopolym. Sci, T
echnol. , 6 (4), 535-546 (199
3), T. Kumada, et al. J. Photo
opolym. Sci, Technol. , 6 (4),
571-574 (1993)]. There is still no chemically amplified positive resist that solves this problem and is satisfactory.

[0006] It is considered that the cause of the PED problem in the chemically amplified positive resist is that the basic compound in the air is largely involved. The acid on the resist surface generated by exposure reacts with and deactivates the basic compound in the air, and PEB
The longer the standing time is, the more the amount of deactivated acid increases, and thus the acid labile group is less likely to decompose.
Therefore, a poorly soluble layer is formed on the surface, and the pattern becomes a T-top shape.

However, by adding a small amount of a basic compound to the chemically amplified positive resist, the acid concentration distribution at the mask edge portion can be made sharp even if the optical contrast of the mask pattern is lowered near the resolution limit. It is known that the controllability is improved, and the acid generated by light interference in the mask light-shielding portion is completely neutralized by the basic compound, so that the problem of resist scum is solved (Japanese Patent Laid-Open No. 5-127369). Issue).

Further, it is known that the addition of a basic compound can suppress the influence of the basic compound in the air, and therefore it is also effective for PED (Japanese Patent Laid-Open No. 232706/1993). No. 5-249683),
The basic compound used here is not incorporated into the resist film due to volatilization, has poor compatibility with each component of the resist, and has a non-uniform dispersion in the resist film width, which causes a problem in reproducibility of the effect. Yes, it was found that the resolution was reduced.

The present invention has been made in view of the above circumstances.
The problem of the surface insoluble layer that causes the T-top shape, that is, P
It is an object of the present invention to provide a novel sulfonium salt suitable as a component of a chemically amplified positive resist material suitable for a microfabrication technique for solving the problem of ED and a chemically amplified positive resist material containing this sulfonium salt.

[0010]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above object, the present inventor has found that, for example, a sulfoxide compound represented by the following general formula (3) is added to trimethylsilyl triflate and the following general formula. By reacting the aryl Grignard reagent represented by (4), a sulfonium salt having a novel nitrogen-containing aromatic group represented by the following general formula (1) can be obtained, and this sulfonium salt can have a T-top shape. Suitable as a component of a chemically amplified positive resist material suitable for a microfabrication technique that solves the problem of the surface insoluble layer, which is the cause, that is, the problem of PED,
In particular, they have found that they can exert great power in deep ultraviolet lithography.

[0011]

[Chemical 2] (In the formula, R ¹ , R ² and R ³ represent an unsubstituted or substituted aromatic group, and at least one of R ¹ , R ² and R ³ is a substituted aromatic group having an acid labile group and the remaining at least One is a nitrogen-containing aromatic group, or all of R ¹ , R ² , and R ³ are nitrogen-containing aromatic groups.)

The resist material containing the sulfonium salt represented by the general formula (1) of the present invention has the effect of the nitrogen-containing substituent of the sulfonium salt represented by the general formula (1), that is, in the air on the resist surface. The influence of acid deactivation by the basic compound can be made extremely small, so that the formation of a surface-insoluble layer is suppressed, and the nitrogen-containing substituent that is a basic group is a sulfonium salt whose acid generator is an acid generator. It has good compatibility with each component of the resist,
Since the dispersion in the resist film is uniform, there is no problem in the reproducibility of the effect. Further, in the case of having an acid labile group, it is possible to enhance the contrast by the effect of the acid labile group, and to solve the problem of the surface-insoluble layer which is the cause of the T-top shape, that is, the problem of PED. It is possible to provide a novel sulfonium salt suitable as a component of a chemically amplified positive type resist material suitable for a fine processing technique to be solved and a chemically amplified positive type resist material containing the sulfonium salt.

Therefore, the present invention provides a sulfonium salt represented by the above general formula (1), and a chemically amplified positive resist material containing the sulfonium salt.

In this case, as the resist material, from the viewpoint of reliably exerting the above effects, (A) an organic solvent (B) an alkali-soluble resin (C) a dissolution inhibitor having an acid labile group (D) the sulfonium salt (E) Onium salt represented by the following general formula (2) or other acid generator (R) _n MY ... (2) (In the formula, R represents the same or different unsubstituted or substituted aromatic group, and M Represents sulfonium or iodonium, Y represents p-toluenesulfonate or trifluoromethanesulfonate, n represents 2 or 3, and (A) an organic solvent (B) an alkali-soluble resin (C). Dissolution inhibitor having acid labile group (D) A resist material containing the sulfonium salt is effectively used.

The present invention will be described in more detail below. The novel sulfonium salt of the present invention has the following general formula (1):
It is a sulfonium salt represented by.

[0016]

[Chemical 3]

In the above formula (1), R ¹ , R ² , R ³
Is an unsubstituted or substituted aromatic group, at least one of R ¹ , R ² and R ³ is a substituted aromatic group having an acid labile group, and at least one of the remaining is a nitrogen-containing aromatic group. , Or R ¹ , R ² and R ³ are all nitrogen-containing aromatic groups. Examples of the unsubstituted aromatic group include a phenyl group, and examples of the substituted aromatic group having an acid labile group include ter.
A t-butoxyphenyl group may be mentioned. As the nitrogen-containing aromatic group, a dialkylaminophenyl group having an alkyl group having 1 to 8 carbon atoms, a picolinyloxyphenyl group, and a pyridinyl group are preferable, and among them, a dimethylaminophenyl group, a diethylaminophenyl group, and a picolinyloxyphenyl group. A group and a pyridinyl group are more preferably used.

A specific example of the sulfonium salt of the above formula (1) is bis (p-trifluoromethanesulfonic acid).
tert-butoxyphenyl) (p-dimethylaminophenyl) sulfonium, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) bis (p-dimethylaminophenyl) sulfonium, trifluoromethanesulfonic acid bis (p-tert-butoxyphenyl)
(P-picolinyloxyphenyl) sulfonium, (p-tert-butoxyphenyl) bis (p-picolyloxyphenyl) sulfonium trifluoromethanesulfonate,
Trifluoromethanesulfonic acid (p-tert-butoxyphenyl) (p-dimethylaminophenyl) phenylsulfonium, trifluoromethanesulfonic acid (pt)
ert-butoxyphenyl) (p-picolyloxyphenyl) phenylsulfonium, bis (p-tert-butoxyphenyl) trifluoromethanesulfonate (pyridin-4-yl) sulfonium, bis (p-tert-butoxyphenyl) trifluoromethanesulfonate Examples include (pyridin-3-yl) sulfonium, bis (p-tert-butoxyphenyl) trifluoromethanesulfonate (pyridin-2-yl) sulfonium, and tris (4-dimethylaminophenyl) sulfonium trifluoromethanesulfonate.

The sulfonium salt of the formula (1) of the present invention is obtained by reacting a sulfoxide compound represented by the following general formula (3) with trimethylsilyl triflate and then forming a THF (tetrahydrofuran) represented by the following general formula (4). It can be synthesized by reacting the prepared aryl Grignard reagent in the organic solvent.

[0020]

[Chemical 4]

In this case, the above reaction is carried out using methylene chloride, TH
It is preferably carried out in an organic solvent such as F. When trimethylsilyl triflate is reacted with the sulfoxide compound represented by the formula (3), trimethylsilyl triflate is added dropwise to the sulfoxide compound (3) at a ratio of 1 to 2 mol to give the sulfoxide compound represented by the formula (3). When R ¹ or R ² has an acid labile group, it is preferably carried out in the presence of a base such as triethylamine or pyridine. The reaction conditions are −78 to 0 ° C. and 10 to
It is preferably 60 minutes.

Further, when reacting the prepared aryl Grignard reagent (4) in an organic solvent such as THF, -78 is used.
It is preferable to add the aryl Grignard reagent (4) at a ratio of 1 to 3 mol to the sulfoxide compound (3) at ˜0 ° C. The aging conditions for the reaction are preferably 0 to 40 ° C. and 0.5 to 2 hours. After completion of the reaction, the solvent layer is washed with water and concentrated, and then recrystallization or column fractionation is carried out to obtain the desired sulfonium salt of the formula (1).

The chemically amplified positive resist composition of the present invention contains a sulfonium salt represented by the above general formula (1), and is a two-component system (alkali-soluble resin / acid generator) or a three-component system (alkali-soluble resin). / Acid generator / dissolution inhibitor) chemically amplified and can be used as an acid generator of a positive resist composition or added to them. It is preferable to use it by adding it to a three-component chemically amplified positive type resist. This resist material is (A)
Organic solvent 150 to 700 parts (weight part, the same hereinafter), preferably 250 to 500 parts, (B) alkali-soluble resin 7
0-90 parts, preferably 75-85 parts, (C) acid labile dissolution inhibitor 0-40 parts, preferably 10-2
5 parts, (D) 0.1 to 5 parts, preferably 0.8 to 4 parts of the sulfonium salt represented by the general formula (1), 0 to 15 parts of (E) acid generator, preferably 2 to 8 parts. A mixture of the above is preferable.

Here, as the organic solvent of the component (A),
Cyclohexanone, ketones such as methyl-2-n-amyl ketone, 3-methoxybutanol, 3-methyl-3
-Alcohols such as methoxycybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether ,
Ethers such as diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl-3-methoxypropionate, ethyl-3-ethoxypropionate, etc. Examples thereof include one kind or two or more kinds. At this time, 1-ethoxy-2-propanol, which has the highest solubility of the acid generator of the resist component, is preferably used.

Examples of the alkali-soluble resin as the component (B) include polyhydroxystyrene and its derivatives. Preferably, polyhydroxystyrene in which the OH group is partially substituted with an acid labile group is used. In this case, the acid labile substituent is tert
-Butyl group, tert-butoxycarbonyl group, tetrahydropyranyl group and the like are preferable, and the degree of substitution is 10 to 50.
Mol%, weight average molecular weight 5,000-100,000
It is preferable that

The dissolution inhibitor of the component (C) has at least one group decomposable by an acid (acid labile group) in the molecule, and may be a low molecular weight compound or polymer. Good. As the dissolution inhibitor, known compounds can be used, and examples of the low molecular weight compound include a bisphenol A derivative having an acid labile group and a carbonic acid ester derivative. Particularly, the OH group of bisphenol A is t-
A compound substituted with a butoxy group or a butoxycarbonyloxy group is preferable. Examples of polymer dissolution inhibitors include:
Examples thereof include copolymers of p-butoxystyrene and t-butyl acrylate and copolymers of p-butoxystyrene and maleic anhydride. In this case, the weight average molecular weight is preferably 500 to 10,000.

Examples of the acid generator as the component (E) include onium salts, oxime sulfonic acid derivatives, 2,6-dinitrobenzyl sulfonic acid derivatives, diazonaphthoquinone sulfonic acid ester derivatives, 2,4-bistrichloromethyl-6-.
Aryl-1,3,5-triazine derivative, α, α'-
Examples thereof include bisarylsulfonyldiazomethane derivatives. An onium salt represented by the following formula (2) (R) _n MY ... (2) is preferable.

Here, R is the same or different type of unsubstituted or substituted aromatic group such as phenyl group, tert-butoxycarbonyloxyphenyl group, tert-butoxyphenyl group, tert-butylphenyl group, methoxyphenyl group, hydroxyphenyl. A group such as M, sulfonium or iodonium, and Y is p-toluenesulfonate or trifluoromethanesulfonate. Also, n is 2 or 3.

Specific examples of such an onium salt include the following iodonium salts and sulfonium salts.

[0030]

[Chemical 5]

Further, the resist material of the present invention may be added with an additive such as a surfactant for improving the coating property and an absorptive material for reducing the influence of irregular reflection from the substrate.

The method of using the resist material of the present invention, the method of using light, and the like can be carried out by employing a known lithography technique. Particularly, the resist material of the present invention is 254 to 19
It is optimal for fine patterning with 3 nm deep ultraviolet light and electron beam.

[0033]

INDUSTRIAL APPLICABILITY The resist material of the present invention is a positive resist material sensitive to high energy rays, especially KrF excimer laser, and is excellent in sensitivity, resolution and plasma etching resistance, and is also excellent in heat resistance of a resist pattern. ing. In addition, it is a chemically amplified positive resist material suitable for a fine processing technology that solves the problem of the surface-insoluble layer that causes the T-top shape, that is, the problem of PED. The novel sulfonium salt of the present invention is a chemically amplified positive resist material. It is effective as a component of a mold resist material.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples of sulfonium salt synthesis and resist materials of the present invention, but the present invention is not limited to the following examples.

Synthesis Example 1 Bis (p-tert-butane ) trifluoromethanesulfonate
Toxyphenyl) (p-dimethylaminophenyl) sul
Synthesis of Fonium 8.5 g (0.025 mol) of bis (p-tert-butoxyphenyl) sulfoxide, 1.3 of triethylamine
g (0.013 mol) in 110 g of methylene chloride was used to prepare a solution of -70 using a dry ice methanol bath.
After cooling to ° C, trimethylsilyl triflate 6.0
g (0.027 mol) was added dropwise with stirring while controlling the temperature so as not to exceed -60 ° C.

Then, the dry ice methanol bath was replaced with an ice water bath, the reaction temperature was adjusted to 0 to 5 ° C., and the mixture was stirred for 10 minutes.

The resulting reaction solution was cooled again to -70 ° C. using a dry ice methanol bath, to which 1.2 g (0.049 mol) of magnesium metal, 18.9 g of tetrahydrofuran and 4-bromo-N, were added. A Grineer reagent prepared by a conventional method using 9.9 g (0.049 mol) of N-dimethylaniline was added dropwise while controlling the reaction temperature so as not to exceed -60 ° C.

Next, the ice water bath was replaced again and the reaction temperature was adjusted to 0 to
The reaction was terminated by stirring at 60 ° C. for another 60 minutes.

Water was added dropwise to the resulting reaction solution to decompose excess Grineer's reagent, and then filtration was performed to remove the produced inorganic salt. The obtained filtrate was washed 3 times with 130 g of water. The obtained organic layer was dried under reduced pressure to obtain an oily substance. The obtained oily substance was applied to a silica gel column chromatograph to give a yield of 4.8 g (yield 32%) and a purity of 98%.
Bis (p-tert-) trifluoromethanesulfonate
Butoxyphenyl) (p-dimethylaminophenyl) sulfonium was isolated.

The results of nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR), and elemental analysis values of the obtained bis (p-tert-butoxyphenyl) trifluoromethanesulfonate (p-dimethylaminophenyl) sulfonium were obtained. Shown below. < ¹ H-NMR: CDCl ₃ , δ (ppm)>

[0041]

[Chemical 6] (A) 1.38 singlet 18H (b) 3.00 singlet 6H (c) 6.76 to 6.79 doublet 2H (e) 7.11 to 7.15 doublet 4H (d), (F) 7.40 to 7.45 multiplet 6H <IR: (cm ^-1 )> 3095, 3072, 2980,
2935, 2873, 2827, 1589, 1520,
1489, 1446, 1373, 1308, 1265,
1223, 1203, 1157, 1074, 1030,
991, 927, 892, 816 <Elemental analysis value: (%) C ₂₉ H ₃₆ F ₃ NO ₅ > Theoretical value C: 58.1 H: 6.0 N: 2.3 Actual value C: 57.8 H: 6.3 N: 2.2

[Reference Example] 24.3 g (1 mol) of magnesium, p-tert-butoxyphenyl chloride 20
A Grignard reagent prepared by a conventional method using 3.2 g (1.1 mol) and 280 g of THF was diluted with 500 g of THF, and cooled to -60 ° C or lower in a doilla ice methanol bath. Then, 47.5 g (0.4 mol) of thionyl chloride was added to T
The solution diluted with 70 g of HF was added dropwise over 1 hour at a temperature not exceeding 0 ° C. After aging for 1 hour in an ice bath, 36 g of water was added to decompose excess Grignard reagent. 400 g of a saturated ammonium chloride aqueous solution and 300 g of water were further added to 1000 g of methylene chloride for liquid separation, and the organic solvent layer was washed with 700 g of pure water twice. The organic solvent layer was dried over magnesium sulfate and filtered, and the solvent was distilled off under reduced pressure. By recrystallizing the obtained oily substance, the target compound bis (p-
tert-butoxyphenyl) sulfoxide to a purity of 96
%, Melting point 80-82 ° C. as white crystals 83 g (yield 6
0%) was obtained.

[0043]

[Chemical 7]<¹H-NMR: CDCl₃, Δ (ppm)> Nuclear magnetic resonance
Spectra 1.34 Ha Singlet 18H 7.01 to 7.04 Hb Doublet 4H 7.48 to 7.51 Hc Doublet 4H <IR: (cm^-1)> 2976, 2931, 1589,
1487, 1392, 1367, 1302, 1238,
1159, 1090, 1043, 1009, 930, 8
93,852,827<MS: (m / z)> Mass spectrum 346 (M⁺): 331,290 (C₂₀H₂₆O₃S = 34
6) <m. p. : (° C)> melting point 80 to 82 ° C

[Synthesis Example 2] Trifluoromethanesulfonic acid (p-tert-butoxy)
Cyphenyl) bis (p-dimethylaminophenyl) sul
Synthesis of Fonium Bis (p-dimethylaminophenyl) sulfoxide 7.
A solution prepared by dissolving 0 g (0.024 mol) in 100 g of methylene chloride was dried by using a dry ice methanol bath, and then -7.
After cooling to 0 ° C., trimethylsilyl triflate 6.
0 g (0.027 mol) was stirred and added dropwise while controlling the temperature so as not to exceed -60 ° C.

Then, the dry ice methanol bath was replaced with an ice water bath, the reaction temperature was adjusted to 0 to 5 ° C., and the mixture was stirred for 10 minutes.

The obtained reaction solution was cooled to -70 ° C. again using a dry ice methanol bath, and 1.2 g (0.049 mol) of magnesium metal, 13.4 g of tetrahydrofuran and p-tert-butoxyphenyl were added thereto. Grineer reagent prepared by a conventional method using 9.8 g (0.053 mol) of chloride was added dropwise while controlling the reaction temperature so as not to exceed −60 ° C.

Then, the ice water bath was replaced again, and the reaction temperature was adjusted to 0 to
The reaction was terminated by stirring at 60 ° C. for another 60 minutes.

Water was added dropwise to the resulting reaction solution to decompose excess Grineer's reagent, and then filtration was performed to remove the produced inorganic salt. The obtained filtrate was washed 3 times with 130 g of water. The obtained organic layer was dried under reduced pressure to obtain an oily substance. The obtained oily substance was applied to a silica gel column chromatograph to give a yield of 3.9 g (yield 28%) and a purity of 99%.
Of (p-tert-butoxyphenyl) bis (p-dimethylaminophenyl) sulfonium trifluoromethanesulfonate was isolated.

The results of nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR) and elemental analysis values of the obtained (p-tert-butoxyphenyl) bis (p-dimethylaminophenyl) sulfonium trifluoromethanesulfonate are shown. Shown below. < ¹ H-NMR: CDCl ₃ , δ (ppm)>

[0050]

[Chemical 8] (A) 1.36 singlet 9H (b) 2.99 singlet 12H (c) 6.73 to 6.76 doublet 4H (e) 7.08 to 7.11 doublet 2H (d), (F) 7.29 to 7.34 multiplet 6H <IR: (cm ^-1 )> 3097, 2978, 2929,
2908, 2870, 2825, 1589, 1551,
1518, 1487, 1446, 1373, 1265,
1223, 1200, 1155, 1074, 1030,
991,943,893,816 <Elemental _{analysis: (%) C 27 H 33} F 3 N 2 O 4 S 2> theory C: 56.8 H: 5.8 N: 4.9 Found C: 56 .6 H: 6.1 N: 4.9

[Synthesis Example 3] Trifluoromethanesulfonic acid tris (4-dimethylacetate)
Synthesis of Minophenyl) sulfonium Bis (4-dimethylaminophenyl) sulfoxide 7.
A solution prepared by dissolving 0 g (0.024 mol) in 100 g of methylene chloride was dried by using a dry ice methanol bath, and then -7.
After cooling to 0 ° C., trimethylsilyl triflate 6.
0 g (0.027 mol) was stirred and added dropwise at a temperature not exceeding -60 ° C.

Then, the dry ice methanol bath was replaced with an ice water bath, the reaction temperature was adjusted to 0 to 5 ° C., and the mixture was stirred for 10 minutes.

The obtained reaction solution was cooled to −70 ° C. again using a dry ice methanol bath, and then 9.9 g (0.049 mol) of 4-bromo-N, N-dimethylaniline and magnesium 1. A Grignard reagent prepared by a conventional method using 2 g (0.049 mol) and 20 g of tetrahydrofuran was stirred and added dropwise at a temperature at which the reaction temperature did not exceed -60 ° C.

Next, the ice water bath was replaced again and the reaction temperature was adjusted to 0 to
The reaction was terminated by stirring at 5 ° C for 60 minutes.

300 g of a 15% ammonium chloride aqueous solution was added to this reaction solution to carry out liquid separation, and then the organic solvent layer was washed twice with 150 g of water. The solvent was distilled off from the obtained organic layer under reduced pressure using a rotary evaporator to obtain an oily substance. The obtained oily substance was subjected to silica gel column chromatography to give a yield of 5.2 g (yield 40%) and a purity of 99%.
Tris (4-dimethylaminophenyl) sulfonium trifluoromethanesulfonate was obtained.

Nuclear magnetic resonance spectrum (NMR) and infrared spectrum (I) of the obtained trifluoromethanesulfonate tris (4-dimethylaminophenyl) sulfonium
The results of R) and elemental analysis values are shown below. < ¹ H-NMR: CDCl ₃ , δ (ppm)>

[0057]

[Chemical 9] (A) 3.01 singlet 18H (b) 6.72 to 6.75 doublet 6H (c) 7.23 to 7.26 doublet 6H <IR: (cm ^-1 )> 2910, 1591, 1550,
1515, 1444, 1375, 1272, 1222
1199, 1145, 1076, 1031, 991, 9
43,811,638,520 <Elemental _{analysis: (%) C 25 H 30} O 3 N 3 S 2 F 3> theory C: 55.4 H: 5.6 N: 7.8 Found C: 55 .3 H: 5.6 N: 7.7

[Examples 1 to 11 and Comparative Examples 1 to 4] OH groups partially represented by the following formula (Polym.
Polyhydroxystyrene protected with butoxycarbonyl group, partially represented by the following formula (Polym.
A polyhydroxystyrene in which the H group is protected by a t-butyl group, or a polyhydroxystyrene in which an OH group partially represented by the following formula (Polym.3) is protected by a tetrahydroxypyranyl group, and a polyhydroxystyrene represented by the following formula (PAG. ) To (PAG.7), an acid generator selected from onium salts and 2,2 ′ represented by the following formula (DRI.1):
A dissolution inhibitor of -bis (4-tert-butoxycarbonyloxyphenyl) propane was dissolved in 1-ethoxy-2-propanol, and resist solutions having the compositions shown in Tables 1 and 2 were prepared.

A resist solution was prepared by filtering each of these compositions through a 0.2 μm Teflon filter. This was spin-coated on a silicone wafer and coated to 1.0 μm. Then, the silicone wafer was baked on a hot plate at 100 ° C. for 120 seconds.

Then, the film was exposed using an excimer laser stepper (NSR 2005EX NA = 0.5, manufactured by Nikon Corporation), baked at 90 ° C. for 60 seconds, and developed with an aqueous solution of 2.38% tetramethylammonium hydroxide. When done, a positive pattern could be obtained.

The obtained resist pattern was evaluated as follows. First, the sensitivity (Eth value) was obtained. Next, 0.
4μm line and space top and bottom 1:
The exposure dose resolved in 1 was taken as the optimum exposure dose, and the minimum line width of the separated lines and spaces in this exposure dose was taken as the resolution of the evaluation resist. The shape of the resolved resist pattern was observed using a scanning electron microscope. The stability of the PED of the resist is determined by changing the standing time after the exposure at the optimum exposure amount and baking, and the time when the change of the resist pattern shape is observed, for example, the line pattern becomes the T-top shape, or the resolution can be resolved. It was evaluated by the time when it disappeared. That is, the longer this time, the better the PED stability. The evaluation results are shown in Table 1 and Comparative Example.

[0062]

[Chemical 10]

[0063]

[Chemical 11]

[0064]

[Chemical 12] In addition, PAG. 4 and PAG. 5 was synthesized in the same manner as in the above synthesis example.

[0065]

[Chemical 13]

[0066]

[Table 1]

[0067]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H05K 3/08 A (72) Inventor Katsuya Takemura 28-1 Nishifukushima Nishikofukuri, Nakakubiki-gun, Niigata prefecture Shin-Etsu Chemical Co., Ltd.Synthesis Technology Laboratory (72) Inventor Toshinobu Ishihara 28-1 Nishikofukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture Shin-Etsu Chemical Co., Ltd. Synthetic Technology Laboratory (72) Inventor Kazumasa Maruyama Nakakubiki, Niigata Prefecture 28-1 Nishi-Fukushima, Kubiki, Gun-gun Synthetic Technology Laboratory, Shin-Etsu Chemical Co., Ltd.

Claims (6)

[Claims] 1. A sulfonium salt represented by the following general formula (1): [Chemical 1] (In the formula, R ¹ , R ² and R ³ represent an unsubstituted or substituted aromatic group, and at least one of R ¹ , R ² and R ³ is a substituted aromatic group having an acid labile group and the remaining at least One is a nitrogen-containing aromatic group, or all of R ¹ , R ² , and R ³ are nitrogen-containing aromatic groups.) 2. A substituted aromatic group having an acid labile group is te.
The sulfonium salt according to claim 1, which is an rt-butoxyphenyl group and the nitrogen-containing aromatic group is a dialkylaminophenyl group having 1 to 8 carbon atoms, a picolinyloxyphenyl group or a pyridinyl group of the alkyl group. 3. A chemically amplified positive type resist material containing the sulfonium salt according to claim 1. 4. (A) Organic solvent (B) Alkali-soluble resin (C) Dissolution inhibitor having acid labile group (D) Containing sulfonium salt (E) Acid generator according to claim 1 or 2. And a chemically amplified positive resist material. 5. An organic solvent (A), an alkali-soluble resin (B), a dissolution inhibitor (C) having an acid labile group, and (D) a sulfonium salt according to claim 1 or 2. Chemically amplified positive resist material. 6. The component (B), which is an alkali-soluble resin, is polyhydroxystyrene having a weight average molecular weight of 5,000 to 100,000 in which some hydrogen atoms of hydroxyl groups are substituted with acid labile groups. 4. The resist material according to 4 or 5.