JPH08157451A - Novel sulfonium salt and method for producing the same - Google Patents

Abstract

(57) [Summary] [Structure] A novel sulfonium salt represented by the following general formula (1). Embedded image (In the formula, R ₁ represents a hydrogen atom, an alkyl group or an alkoxy group, and Y represents trifluoromethanesulfonate or p-
Indicates toluene sulfonate. n is an integer of 0 to 2, m is an integer of 1 to 3, and n + m = 3. [Effect] The novel sulfonium salt of the present invention has at least one tert-butoxycarbonylmethoxy group, which is an acid labile group, introduced into the sulfonium salt which is an acid generator, so that the exposed and unexposed areas can be Since the dissolution contrast can be increased, it is effective as a component of a chemically amplified positive resist material having high resolution suitable for microfabrication technology, and contains the sulfonium salt represented by the general formula (1) of the present invention. The resist material to be used has a high sensitivity as a positive resist material to high-energy rays such as deep ultraviolet rays, electron beams, and X-rays, particularly KrF excimer laser, and can be formed into a pattern by developing with an alkaline aqueous solution. Excellent resolution and plasma etching resistance,
Moreover, the heat resistance of the resist pattern is also excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel sulfonium salt suitable as a component of a chemically amplified positive resist material suitable for microfabrication technology and a method for producing the same.

[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 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. Deep-UV lithography can also process 0.3 to 0.4 μm, and when a resist material having low light absorption is used, a pattern shape having a side wall that is nearly vertical to the substrate becomes possible. In recent years, K, which has a high brightness as a light source for far-ultraviolet rays
A technique utilizing an rF excimer laser has been drawing attention, and a resist material having low light absorption and high sensitivity is required for its use as a mass production technique.

From these points, a chemically amplified resist material using an acid as a catalyst developed in recent years (Japanese Patent Publication No. 27660/1990).
And Japanese Patent Laid-Open No. 63-27829) are particularly promising resist materials for deep ultraviolet lithography which have high sensitivity, resolution and dry etching resistance and have excellent characteristics.

In this case, in the chemically amplified positive resist material, it is known that the acid generator used has a particularly large influence on the function as the chemically amplified resist material. Specific examples include the onium salts shown below.

[0006]

[Chemical 4]

Since the onium salt itself is an oil-soluble compound, when it is compounded as a resist component, it has the effect of reducing the solubility of the resist material in an alkaline aqueous solution and suppressing the film loss during development.

However, in the case of a positive resist material, in the exposed area, the decomposition product produced by the absorption of the high energy rays by the acid generator is also oil-soluble, so that it dissolves in the alkaline aqueous solution in the exposed area. It is not possible to reduce the speed and increase the ratio of the alkali dissolution rate between the exposed area and the unexposed area (called dissolution contrast). Therefore, the chemically amplified resist using the above-mentioned onium salt is resolved during alkali development. The pattern shape is not rectangular because it has poor transparency, that is, the exposed part is not easily removed.
There was a defect that it became a trapezoidal forward taper.

In order to solve this problem, a tert-butoxycarbonyl group, which is an acid labile group, is introduced into p-hydroxyphenylsulfonium salt and decomposed by high-energy radiation to generate an acid, which has alkali solubility. A phenol derivative is produced to increase the dissolution contrast (Japanese Patent Laid-Open No. 64-26550).
64-35433 and JP-A-2-12153).

However, even if a sulfonium salt which produces such a phenol derivative is used, high resolution is not satisfied.

Further, the conventional chemically amplified positive resist material is exposed to PEB (Post Exposure B) when exposed to deep ultraviolet rays, electron beams and X-ray lithography.
The problem that the line pattern becomes a T-top shape when the pattern is formed, that is, the upper part of the pattern becomes thick when the standing time before ake) becomes long [PED (PostE
xposure 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, and there is a problem that the dimension controllability is impaired even when the substrate is processed using dry etching [Reference: W. Hinsberg, et a
l. , J. et al. Photopolym. Sci. Techn
ol. , 6 (4), 535-546 (1993). ,
T. Kumada, et al. , J. et al. Photopo
lym. Sci. Technol. , 6 (4), 571
-574 (1993). ]. There is no chemically amplified positive resist material that solves this problem and is satisfactory.

In the chemically amplified positive resist material, P
It is believed that basic compounds in air are largely involved in the cause of ED problems. The acid on the resist surface generated by exposure reacts with the basic compound in the air, deactivates,
The longer the standing time to PEB is, the more the amount of deactivated acid increases, and thus the acid labile group is less likely to be decomposed. Therefore, a poorly soluble layer is formed on the surface, and the pattern is T
-It becomes a top shape.

However, it is known that the addition of a basic compound can suppress the influence of the basic compound in the air, and thus it is also effective for PED (Japanese Patent Laid-Open No. 232706/1993). JP-A-5-24968
No. 3), the basic compound used here is not incorporated into the resist film due to volatilization or has poor compatibility with each component of the resist and its dispersion in the resist film is non-uniform, so that the effect is reproduced. It was found that there is a problem with the image quality and the resolution is reduced.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a novel sulfonium salt suitable as a component of a chemically amplified positive type resist material having high resolution suitable for microfabrication technology and a method for producing the same.

[0015]

Means and Actions for Solving the Problems As a result of various studies to achieve the above object, the present inventor found that, for example, the following general formula (2) described in Japanese Patent Application No. 5-242101 or 6-82359. The p-tert-butoxyphenylsulfonium salt represented by is deprotected with sulfonic acid (3) to obtain p-hydroxyphenylsulfonium salt (4), followed by α-halogenated tert-butyl acetate (5). By reacting under basic conditions, a novel sulfonium salt having at least one tert-butoxycarbonylmethoxy group as an acid labile group represented by the following general formula (1) is obtained, and these sulfonium salts (1) are finely divided. Suitable as a component of chemically amplified positive resist material with high resolution suitable for processing technology, especially in deep ultraviolet lithography It was found to be capable of exhibiting the power.

[0016]

Embedded image (In the formula, R ₁ represents a hydrogen atom, an alkyl group or an alkoxy group, X represents a chlorine atom or a bromine atom, Y represents trifluoromethanesulfonate or p-toluenesulfonate, n is an integer of 0 to 2, and m is 1 Is an integer of 3 and n + m =
It is 3. )

The sulfonium salt represented by the above general formula (1) of the present invention is used as a component of a resist material,
Due to the effect of the acid labile group, a chemically amplified positive resist material having a large dissolution contrast and a high resolution suitable for a fine processing technique can be provided.

That is, although the sulfonium salt of the present invention has a low alkali solubility of the compound itself, the acid and PEB (Post) generated by decomposition by irradiation with high energy rays are used.
Due to the action of Exposure Bake), t
Since the ert-butyl ester is decomposed to generate a carboxylic acid derivative having a higher alkali solubility than the phenol derivative, a larger dissolution contrast can be obtained. Therefore, the novel sulfonium salt of the present invention can exhibit excellent performance as an acid generator of a chemically amplified positive resist material, and can obtain a resist image having high resolution and a wide depth of focus.

Therefore, in the present invention, the sulfonium salt of the formula (1) and the p-tert-butoxyphenylsulfonium salt of the formula (2) are deprotected with the sulfonic acid of the formula (3) to obtain the p- of the formula (4). A method for producing a sulfonium salt of the formula (1), which comprises reacting the α-halogenated tert-butyl acetate of the formula (5) after obtaining the hydroxyphenylsulfonium salt.

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

[0021]

[Chemical 6]

Here, in the above formula (1), n is an integer of 0 to 2, m is an integer of 1 to 3, and the combination of numbers is n + m = 3. R ¹ is a hydrogen atom, an alkyl group or an alkoxy group. As the alkyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, s
ec-butyl group, tert-butyl group, hexyl group, cyclohexyl group and the like having 1 to 8 carbon atoms are preferable,
Among them, methyl group, ethyl group, isopropyl group, tert
-Butyl group is more preferably used. As the alkoxy group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group,
A tert-butoxy group, a hexyloxy group, a cyclohexyloxy group and the like having 1 to 8 carbon atoms are preferable, and among them, a methoxy group, an ethoxy group, an isopropoxy group, and a tert group.
A -butoxy group is more preferably used.

Y represents trifluoromethane sulfonate or p-toluene sulfonate, and the novel sulfonium salt of the present invention is specifically represented by the following formula (1a) or (1
It is shown in b).

[0024]

[Chemical 7] (In the formula, R ₁ , n and m have the same meanings as described above.)

In this case, in particular, by using the sulfonium salt of the formula (1b) as a component of the resist material, the effect of the p-toluenesulfonate anion, that is, deactivation of the acid by the basic compound in the air on the resist surface is used. Since the influence of T can be made extremely small, formation of a surface-insoluble layer can be suppressed, PED stability is good, and T
-Problem with a poorly soluble surface layer that causes the top shape, ie PE
The problem of D can be solved and good sensitivity can be obtained.

Specific examples of the sulfonium salt of the above formula (1a) include tris (p-tert-butoxycarbonylmethoxyphenyl) sulfonium trifluoromethanesulfonate and bis (p-tert-butoxycarbonylmethoxyphenyl) trifluoromethanesulfonate. Phenylsulfonium, bis (p-tert-butoxycarbonylmethoxyphenyl) trifluoromethanesulfonate (p-methylphenyl) sulfonium, bis (p-tert-butoxycarbonylmethoxyphenyl) trifluoromethanesulfonate (m-methylphenyl) sulfonium, trifluoro Bis (p-tert-butoxycarbonylmethoxyphenyl) (o-methylphenyl) sulfonium methanesulfonate, Bis (p) trifluoromethanesulfonate tert- butoxycarbonyl-methoxyphenyl) (p- methoxyphenyl) sulfonium, trifluoromethanesulfonic acid bis (p-
tert-butoxycarbonylmethoxyphenyl) (m
-Methoxyphenyl) sulfonium, trifluoromethanesulfonic acid bis (p-tert-butoxycarbonylmethoxyphenyl) (o-methoxyphenyl) sulfonium, trifluoromethanesulfonic acid (p-tert-)
Butoxycarbonylmethoxyphenyl) diphenylsulfonium, trifluoromethanesulfonic acid (p-ter
t-butoxycarbonylmethoxyphenyl) bis (p-
Methylphenyl) sulfonium, trifluoromethanesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (m-methylphenyl) sulfonium,
Trifluoromethanesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (o-methylphenyl) sulfonium, trifluoromethanesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (p-methoxyphenyl) sulfonium, trifluoromethanesulfonic acid (P-tert-butoxycarbonylmethoxyphenyl) bis (m-methoxyphenyl) sulfonium, trifluoromethanesulfonic acid (p
Examples include -tert-butoxycarbonylmethoxyphenyl) bis (o-methoxyphenyl) sulfonium.

A specific example of the sulfonium salt of the above formula (1b) is p-toluenesulfonic acid tris (pt).
ert-butoxycarbonylmethoxyphenyl) sulfonium, p-toluenesulfonic acid bis (p-tert-)
Butoxycarbonylmethoxyphenyl) phenylsulfonium, p-toluenesulfonic acid bis (p-tert-)
Butoxycarbonylmethoxyphenyl) (p-methylphenyl) sulfonium, bis (p-tert-butoxycarbonylmethoxyphenyl) (m-methylphenyl) sulfonium p-toluenesulfonate, bis (p-tert-butoxycarbonyl) p-toluenesulfonate Methoxyphenyl) (o-methylphenyl) sulfonium, p-toluenesulfonate bis (p-tert-butoxycarbonylmethoxyphenyl) (p-methoxyphenyl) sulfonium, p-toluenesulfonate bis (p
-Tert-butoxycarbonylmethoxyphenyl)
(M-methoxyphenyl) sulfonium, bis (p-tert-butoxycarbonylmethoxyphenyl) (o-methoxyphenyl) sulfonium p-toluenesulfonate, p-toluenesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) diphenylsulfonium, p-toluenesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (p-methylphenyl) sulfonium, p-toluenesulfonic acid (p-te)
rt-Butoxycarbonylmethoxyphenyl) bis (m
-Methylphenyl) sulfonium, p-toluenesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (o-methylphenyl) sulfonium, p-
Toluenesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (p-methoxyphenyl) sulfonium, p-toluenesulfonic acid (p-tert-)
Examples include butoxycarbonylmethoxyphenyl) bis (m-methoxyphenyl) sulfonium and p-toluenesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) bis (o-methoxyphenyl) sulfonium.

The sulfonium salt of the formula (1) of the present invention can be synthesized by the following route (A). That is, using p-tert-butoxyphenylsulfonium salt represented by the following formula (2) as a starting material, deprotection was performed using sulfonic acid (3) corresponding to the counter anion of the sulfonium salt used, and p-hydroxyphenyl The sulfonium salt (4) is obtained, followed by α-halogenated acetic acid tert-
By reacting butyl (5) under basic conditions,
A sulfonium salt (1) having at least one tert-butylcarbonylmethoxy group can be synthesized.

[0029]

Embedded image (In the formula, R ₁ represents a hydrogen atom, an alkyl group or an alkoxy group, X represents a chlorine atom or a bromine atom, Y represents trifluoromethanesulfonate or p-toluenesulfonate, n is an integer of 0 to 2, and m is 1 Is an integer of 3 and n + m =
It is 3. )

In this case, it is desirable to deprotect the p-tert-butoxyphenylsulfonium salt (2) in an organic solvent such as methanol or ethanol, which corresponds to the counter anion of the sulfonium salt used. The sulfonic acid (3) was added to the sulfonium salt at 0.
1 to 0.5 mol, and added under reflux (60 to 70 mol).
It is desirable to carry out the reaction for 2 to 6 hours. After completion of the reaction, the solvent layer is concentrated and the residue is washed with diethyl ether to obtain p-hydroxyphenylsulfonium salt (4). With respect to this sulfonium salt, the following reaction can be carried out with the crude product as it is.

Next, when introducing a t-butoxycarbonylmethoxy group into the p-hydroxyphenylsulfonium salt (4) of this crude product, an organic solvent such as acetone, N, N-dimethylformamide or dimethylsulfoxide is used. It is desirable to carry out the reaction in. A base such as potassium carbonate is added at a ratio of 1 to 2 mol, and t-butyl chloro or bromoacetate (5) is added at a ratio of 1 to 2 mol with respect to one hydroxy group of the p-hydroxyphenylsulfonium salt (4).
The temperature condition is preferably 60 to 90 ° C. and 6 to 8 hours. After completion of the reaction, the solvent layer is washed with water, concentrated and then recrystallized or fractionated by column to obtain the sulfonium salt (1) of the target compound having a t-butoxycarbonylmethoxy group.

The tris (hydroxyphenyl) sulfonium salt can be obtained by the reaction of phenol and thionyl chloride in the presence of aluminum chloride [S. Oae
and C. Zalut, J .; Am. Chem. So
c. , 82.5359. (1960). ], A sulfonium salt having one hydroxy group can be obtained by condensation of diphenyl sulfoxide and phenol with an acid [S.
R. Akhtar, J .; V. Crivello and
J. L. Lee. , J. et al. Org. Chem. , 55.
4222. (1990). ].

However, since the active site of phenol exists not only in the para position but also in the ortho position, there is a possibility that an ortho substitution product will be produced depending on the reagent or catalyst used [C.
Y. Meyers and G.M. Picciola, T
etrahedron Lett. , 971. (196
2). ], It is difficult to quantitatively obtain a p-hydroxy compound.

On the other hand, according to the above reaction route A, since the p-tert-butoxyphenylsulfonium salt is obtained by the Grignard reagent, only the p-hydroxy form is obtained without the formation of the ortho substitution product as in the case of phenol. It can be obtained quantitatively.

The sulfonium salt represented by the above general formula (1) of the present invention is a two-component (alkali-soluble resin / acid generator) or three-component (alkali-soluble resin / acid generator / dissolution inhibitor) chemistry. It can be used as an acid generator for an amplified positive resist material. It is preferably used as an acid generator of a three-component chemically amplified positive resist composition. This resist material contains (A) an organic solvent in an amount of 150 to 700 parts (parts by weight, the same applies hereinafter), preferably 2 parts.
50 to 500 parts, 70 to 9 (B) alkali-soluble resin
0 part, preferably 75 to 85 parts, in the three-component chemical amplification positive resist composition (C), 5 to 40 parts, preferably 10 to 25 parts of the dissolution inhibitor having an acid labile group,
(D) The sulfonium salt represented by the general formula (1) is 1
-15 parts, preferably 2-8 parts, and if necessary, a mixture of (E) another acid generator of 0.5-15 parts, preferably 2-8 parts is suitable.

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 methoxybutanol, 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. Examples of the polyhydroxystyrene derivative include those obtained by partially replacing the hydrogen atom of the hydroxyl group of polyhydroxystyrene with an acid labile group, and a copolymer of hydroxystyrene. In the case of the former, examples of the acid-labile substituent include a tert-butyl group, a tert-butoxycarbonyl group, a tetrahydropyranyl group, a methoxymethyl group, a trimethylsilyl group, and a tert-butyldimethylsilyl group. Butyl group, tert
-Butoxycarbonyl group and tetrahydropyranyl group are preferably used. In the latter case, the copolymer of hydroxystyrene includes a copolymer of hydroxystyrene and styrene, a copolymer of hydroxystyrene and tert-butyl acrylate, a copolymer of hydroxystyrene and tert-butyl methacrylate, Examples thereof include a copolymer of hydroxystyrene and maleic anhydride, a copolymer of hydroxystyrene and di-tert-butyl maleate, and the like. The weight average molecular weight of this polyhydroxystyrene or its derivative is 5,000 to 100,000.
It is preferably 0.

The dissolution inhibitor of the component (C) has one or more groups capable of being decomposed by an acid in the molecule,
It may be a low molecular weight compound or polymer. Examples of the low molecular weight compound include a bisphenol A derivative and a carbonic acid ester derivative, and a compound in which the hydroxyl group of bisphenol A is substituted with a tert-butoxy group or a butoxycarbonyloxy group is particularly preferable. Examples of polymer dissolution inhibitors include copolymers of p-butoxystyrene and tert-butyl acrylate and copolymers of p-butoxystyrene and maleic anhydride. In this case, the weight average molecular weight is 5,000 to 1
10,000 is preferable.

As the acid generator as the component (E), 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.

Preferably, the acid generator has the following general formula:
Use the indicated onium salt. (R ₂)_nMY (In the formula, R ₂Is the same or different unsubstituted or substituted aromatic group
, M is sulfonium or iodonium, and Y is
Is p-toluene sulfonate or trifluoromethane
Denotes lephonate. n represents 2 or 3. )

Here, examples of the aromatic group include a phenyl group and a phenyl group substituted with an alkyl group or an alkoxy group as described in the above formula (1).

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

[0043]

[Chemical 9]

Further, an additive such as a nitrogen-containing compound for the PED stability, a surfactant for improving the coating property, and an absorptive material for reducing diffuse reflection from the substrate are added to the resist material. You can also

For example, the nitrogen-containing compound has a boiling point of 1
Examples thereof include amine compounds or amide compounds at 50 ° C. or higher. Specifically, aniline, N-methylaniline,
N, N-dimethylaniline, o-toluidine, m-toluidine, p-toluidine, 2,4-lutidine, quinoline, isoquinoline, formamide, N-methylformamide, N, N-dimethylformamide, acetamide,
N-methylacetamide, N, N-dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone, imidazole, α-picoline, β-picoline, γ-picoline, o
-Aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2-quinolinecarboxylic acid, 2-amino-4- Nitrophenol,
Examples include triazine compounds such as 2- (p-chlorophenyl) -4,6-trichloromethyl-s-triazine. Among these, especially pyrrolidone, N-methylpyrrolidone, o-aminobenzoic acid, m-aminobenzoic acid, p
-Aminobenzoic acid, 1,2-phenylenediamine, 1,
3-Phenylenediamine and 1,4-phenylenediamine are preferably used.

Further, examples of the surfactant include perfluoroalkyl polyoxyethylene ethanol, fluorinated alkyl ester, perfluoroalkylamine oxide, perfluoroalkyl EO adduct and the like.

Further, examples of the light absorbing material include diaryl sulfoxide, diaryl sulfone, 9,10-dimethylanthracene, 9-fluorenone and the like.

The method of using the resist material, the method of using light and the like can be carried out by adopting a known lithography technique. Especially, the resist material is 254 to 193 nm.
Most suitable for fine patterning with far-ultraviolet light and electron beam.

[0049]

INDUSTRIAL APPLICABILITY The novel sulfonium salt of the present invention has at least one tert-butoxycarbonylmethoxy group, which is an acid labile group, introduced into the sulfonium salt which is an acid generator. The sulfonium salt represented by the general formula (1) of the present invention is effective as a component of a chemically amplified positive type resist material having a high resolution suitable for microfabrication technology because it can increase the dissolution contrast. The contained resist material has a high sensitivity as a positive type resist material to high-energy rays such as deep ultraviolet rays, electron beams, and X-rays, particularly KrF excimer laser, and can be patterned by developing with an alkaline aqueous solution. Excellent resolution and plasma etching resistance, and also excellent heat resistance of the resist pattern.

[0050]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 Trifluoromethanesulfonic acid (p-hydroxyphenyi)
4) g) Synthesis of diphenylsulfonium 48.4 g (p.-tert-butoxyphenyl) diphenylsulfonium trifluoromethanesulfonate (0.
1 mol), trifluoromethanesulfonic acid 1.5 g
(0.01 mol) is dissolved in 500 g of methanol,
The reaction was carried out under reflux (60 to 70 ° C.) for 6 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 100 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. The crude yield was 40 g (93% crude yield). Trifluoromethanesulfonic acid (p-tert-butoxy)
Cycarbonylmethoxyphenyl) diphenylsulfonium
Synthesis of oil-free 40 g, anhydrous potassium carbonate 20.7 g (0.
15 mol), t-butyl chloroacetate 18.1 g (0.
(12 mol) was dissolved in 400 g of acetone (anhydrous potassium carbonate was suspended), and the mixture was reacted under reflux (60 ° C.) for 3 hours.

After the reaction was completed, the produced inorganic salt was filtered, and the obtained organic layer was distilled off under reduced pressure to obtain an oily substance. Column chromatography of this oil gave a yield of 46.1 g.
(P-tert-Butoxycarbonylmethoxyphenyl) diphenylsulfonium trifluoromethanesulfonate having a yield of 85% (two steps) and a purity of 99% was isolated.

The nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR), and elemental analysis results of the obtained trifluoromethanesulfonic acid (p-tert-butoxycarbonylmethoxyphenyl) diphenylsulfonium are shown below.

[0055]

[Chemical 10] (A) 1.46 singlet 9H (b) 4.61 singlet 2H (c) 7.14 to 7.18 doublet 2H (d) to (g) 7.65 to 7.74 multiplet 12H IR : (Cm ^-1 ) 3093, 3066, 2981, 2935, 2881,
1745, 1589, 1497, 1477, 1446,
1417, 1396, 1371, 1319, 1265,
1224, 1155, 1070, 1068, 1066
1030, 997, 943, 836, 752, 684
638 Elemental analysis value: (%) C ₂₅ H ₂₅ O ₆ S ₂ F ₃ theoretical value C: 55.3 H: 4.6 measured value C: 55.2 H: 4.7

Example 2 Bis (p-hydroxyphenyl ) trifluoromethanesulfonate
Synthesis of phenyl) phenylsulfonium bis (p-tert-butoxyphenyl) phenylsulfonium trifluoromethanesulfonate 55.7 g
(0.1 mol), trifluoromethanesulfonic acid 1.
5 g (0.01 mol) was dissolved in 500 g of methanol and reacted under reflux (60 to 70 ° C.) for 7 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 100 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. The crude yield was 42 g (94% crude yield). Bis (p-tert-butane) trifluoromethanesulfonate
Toxycarbonylmethoxyphenyl) phenylsulfoni
Synthesis of Um 42 g of the above oil, 41.5 g of anhydrous potassium carbonate (0.
30 mol) and t-butyl chloroacetate 36.2 g (0.
24 mol) was dissolved in 300 g of dimethyl sulfoxide (anhydrous potassium carbonate was suspended) and reacted at 80 ° C. for 2 hours.

After completion of the reaction, 300 g of water and 300 g of chloroform were added to the reaction solution to separate it. The organic layer is water 300g
After washing twice with, the solvent was distilled off under reduced pressure to obtain an oily substance. This oil was subjected to column chromatography,
Yield 55.1 g (yield 82% (two steps)), purity 99%
Bis (p-tert-) trifluoromethanesulfonate
Butoxycarbonylmethoxyphenyl) phenylsulfonium was isolated.

Nuclear magnetic resonance spectrum (N) of the obtained bis (p-tert-butoxycarbonylmethoxyphenyl) phenylsulfonium trifluoromethanesulfonate.
The results of MR), infrared spectrum (IR), and elemental analysis are shown below.

[0060]

[Chemical 11] (A) 1.45 singlet 18H (b) 4.60 singlet 4H (c) 7.13 to 7.17 doublet 4H (d) to (g) 7.64 to 7.74 multiplet 9H IR : (Cm ^-1 ) 3093, 3066, 2982, 2935, 2881,
1745, 1589, 1497, 1477, 1446,
1418, 1396, 1372, 1319, 1265,
1225, 1155, 1070, 1068, 1065
1030, 997, 942, 836, 752, 684
638 Elemental analysis value: (%) C ₃₁ H ₃₅ O ₉ S ₂ F ₃ theoretical value C: 55.4 H: 5.2 actual measurement value C: 55.1 H: 5.3

[Example 3] Bis (p-hydroxyphenyl ) trifluoromethanesulfonate
Synthesis of (phenyl) (p-methylphenyl) sulfonium 28.5 g (0.05 mol) of bis (p-tert-butoxyphenyl) (p-methylphenyl) sulfonium trifluoromethanesulfonate, 1.5 g of trifluoromethanesulfonic acid (0. 01 mol) to methanol 40
It was dissolved in 0 g and reacted under reflux (60 to 70 ° C.) for 6.5 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 200 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. The crude yield was 22 g (crude yield 96%). Bis (p-tert-butane) trifluoromethanesulfonate
Toxycarbonylmethoxyphenyl) (p-methylphene
Yl) Synthesis of oil 22g sulfonium, anhydrous potassium carbonate 20.7 g (0.
15 mol), t-butyl chloroacetate 22.6 g (0.
15 mol) to N, N-dimethylformamide 150 g
(Dissolved in anhydrous potassium carbonate) and reacted at 80 ° C. for 3 hours.

After completion of the reaction, 200 g of water and 200 g of chloroform were added to the reaction solution to separate it. 150g of water in the organic layer
After washing three times with, the solvent was distilled off under reduced pressure to obtain an oily substance. This oil was subjected to column chromatography,
Yield 29.0 g (yield 84% (two steps)), purity 98%
Bis (p-tert-) trifluoromethanesulfonate
Butoxycarbonylmethoxyphenyl) (p-methylphenyl) sulfonium was isolated.

The results of nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR), and elemental analysis of the obtained bis (p-tert-butoxycarbonylmethoxyphenyl) (p-methylphenyl) sulfonium trifluoromethanesulfonate are shown. Shown below.

[0065]

[Chemical 12] (A) 1.41 singlet 18H (b) 4.60 singlet 4H (c) 7.13 to 7.17 doublet 4H (d) to (f) 7.64 to 7.74 multiplet 8H ( g) 2.43 singlet 3H IR: (cm ^-1 ) 3093, 3066, 2981, 2935, 2881,
1746, 1589, 1497, 1477, 1446,
1417, 1394, 1371, 1319, 1265,
1224, 1157, 1071, 1068, 1066
1032, 997, 945, 836, 752, 685
638 Elemental analysis value: (%) C ₃₂ H ₃₇ O ₉ S ₂ F ₃ theoretical value C: 56.0 H: 5.4 actual measurement value C: 55.6 H: 5.3

Example 4 Trifluoromethanesulfonic acid tris (p-hydroxy)
Synthesis of phenyl) sulfonium trifluoromethanesulfonate tris (p-tert-)
Butoxyphenyl) sulfonium 100g (0.16m
ol), 2.4 g of trifluoromethanesulfonic acid (0.
016 mol) was dissolved in 320 g of ethanol and reacted under reflux (70 to 80 ° C.) for 7 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 150 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. The crude yield was 68 g (crude yield 92%). Trifluoromethanesulfonic acid tris (p-tert-)
Butoxycarbonylmethoxyphenyl) sulfonium
Synthetic oily substance 68 g, anhydrous potassium carbonate 110.8 g
(0.80 mol), t-butyl chloroacetate 120.5
g (0.80 mol) was dissolved in 320 g of N, N-dimethylformamide (anhydrous potassium carbonate was suspended), and 80
The reaction was performed at 0 ° C for 2 hours.

After completion of the reaction, 300 g of water and 300 g of chloroform were added to the reaction solution to separate it. The organic layer is water 300g
After washing twice with, the solvent was distilled off under reduced pressure to obtain an oily substance. This oil was subjected to column chromatography,
Yield 108.0 g (84% yield (two steps)), purity 98
% Trifluoromethanesulfonic acid tris (p-ter)
t-Butoxycarbonylmethoxyphenyl) sulfonium was isolated.

Nuclear magnetic resonance spectrum (NM) of tris (p-tert-butoxycarbonylmethoxyphenyl) sulfonium trifluoromethanesulfonate obtained
The results of R), infrared spectrum (IR), and elemental analysis are shown below.

[0070]

[Chemical 13] (A) 1.45 singlet 27H (b) 4.56 singlet 6H (c) 7.10 to 7.13 doublet 6H (d) 7.57 to 7.60 doublet 6H IR: (cm ^-1 ) 3097, 2981, 2937, 1747, 1589,
1494, 1446, 1417, 1371, 1317,
1263, 1226, 1157, 1076, 1031
944, 833, 752, 638 Elemental analysis value: (%) C ₃₇ H ₄₅ O ₁₂ S ₂ F ₃ Theoretical value C: 55.4 H: 5.7 Actual value C: 55.2 H: 5.6

Example 5 Bis (p-hydroxyphenyl ) p-toluenesulfonate
) Synthesis of phenylsulfonium 5.8 g (0.01 m) of bis (p-tert-butoxyphenyl) phenylsulfonium p-toluenesulfonate
ol), 0.95 g of p-toluenesulfonic acid monohydrate
(0.005 mol) is dissolved in 35 g of methanol,
The reaction was carried out at 60 ° C for 5 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 200 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. Crude yield is 4.7 g (crude yield 100%)
Met. Bis (p-tert-butoxy) p-toluenesulfonate
Carbonylmethoxyphenyl) phenylsulfonium
Synthesis 4.7 g of the above oily substance, 4.1 g of anhydrous potassium carbonate (0.
03 mol), t-butyl chloroacetate 3.6 g (0.0
24 mol) was dissolved in 50 g of dimethylsulfoxide (anhydrous potassium carbonate was suspended) and reacted at 80 ° C. for 2 hours.

After the reaction was completed, 100 g of water and 100 g of chloroform were added to the reaction solution to separate it. 100g water organic layer
After washing twice with, the solvent was distilled off under reduced pressure to obtain an oily substance. This oil was subjected to column chromatography,
Yield 5.6 g (yield 80% (two steps)) and purity 97% bis (p-tert-butoxycarbonylmethoxyphenyl) phenylsulfonium p-toluenesulfonate was isolated.

The obtained p-toluenesulfonate bis (p
-Tert-butoxycarbonylmethoxyphenyl) phenylsulfonium nuclear magnetic resonance spectrum (NM
The results of R), infrared spectrum (IR), and elemental analysis are shown below.

[0075]

Embedded image (A) 1.43 singlet 18H (b) 4.56 singlet 4H (c) 2.26 singlet 3H (d) 7.11 to 7.14 doublet 4H (e) to (h) 7. 52-7.70 Multiplet 9H (i) 7.75-7.78 Doublet 2H (j) 6.99-7.02 Doublet 2H IR: (cm ^-1 ) 3059, 2979, 2933, 1746. , 1583,
1489, 1446, 1394, 1308, 1266,
1204, 1202, 1159, 1119, 1076
1027, 1033, 1012, 928, 895, 84
3,816 Elemental analysis value: (%) C ₃₇ H ₄₂ O ₉ S ₂ Theoretical value C: 64.0 H: 6.1 Actual value C: 63.8 H: 6.0

Example 6 Tris (p-hydroxyphenyl ) p-toluenesulfonate
) Sulfonium synthesis Tris (p-tert-butoxyphenyl) sulfonium p-toluenesulfonate 6.5 g (0.01 mo)
l), 0.95 g of p-toluenesulfonic acid monohydrate
(0.005 mol) is dissolved in 40 g of methanol,
The reaction was carried out at 60 ° C for 7 hours.

After completion of the reaction, the reaction solution was distilled off under reduced pressure to obtain an oily substance. The oil was washed twice with 200 g of diethyl ether. The following reaction was carried out as an oily substance without further purification. The crude yield was 4.7 g (crude yield 97%). p-toluenesulfonic acid tris (p-tert-butoxy)
Synthesis of cycarbonylmethoxyphenyl ) sulfonium 4.7 g of the above oily substance, 6.9 g of anhydrous potassium carbonate (0.
05 mol), t-butyl chloroacetate 7.5 g (0.0
(5 mol) was dissolved in 60 g of dimethyl sulfoxide (anhydrous potassium carbonate was suspended) and reacted at 80 ° C. for 3 hours.

After the reaction was completed, 100 g of water and 100 g of chloroform were added to the reaction solution to separate it. 100g water organic layer
After washing twice with, the solvent was distilled off under reduced pressure to obtain an oily substance. This oil was subjected to column chromatography,
Yield 7.0 g (yield 85% (two steps)) and purity 97% tris (p-tert-butoxycarbonylmethoxyphenyl) sulfonium p-toluenesulfonate were isolated.

Nuclear magnetic resonance spectrum (NMR) of the obtained tris (p-tert-butoxycarbonylmethoxyphenyl) sulfonium p-toluenesulfonate,
The results of infrared spectrum (IR) and elemental analysis are shown below.

[0080]

[Chemical 15] (A) 1.41 singlet 27H (b) 4.56 singlet 6H (c) 7.11 to 7.14 doublet 6H (d) 7.64 to 7.67 doublet 6H (e) 2 .27 singlet 3H (f) 7.03 to 7.06 doublet 2H (g) 7.80 to 7.83 doublet 2H IR: (cm ^-1 ) 3059, 2979, 2933, 1747, 1583,
1488, 1447, 1396, 1308, 1265,
1203, 1201, 1159, 1120, 1076
1028, 1034, 1012, 928, 895, 84
4,816 Elemental analysis value: (%) C ₄₃ H ₅₂ O ₁₂ S ₂ theoretical value C: 62.6 H: 6.4 actual measurement value C: 62.9 H: 6.2

Reference Example 1 Polyhydroxystyrene in which a hydroxyl group represented by the following formula (Polym.1) is partially protected by t-butoxycarbonyl group, and the following formula (Poly).
m. 2) Polyhydroxystyrene in which the hydroxyl groups are partially protected by t-butyl groups, or the following formula (Po
lym. 3) polyhydroxystyrene in which a hydroxyl group is partially protected by a tetrahydropyranyl group, an acid generator selected from the onium salts represented by the following formulas (PAG.1) to (PAG.5), and the following formula: (DRI.1) 2,2'-bis (4-tert-butoxycarbonyloxyphenyl) propane dissolution inhibitor was dissolved in 1-ethoxy-2-propanol to prepare a resist solution having the composition shown in Table 1. 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 0.8 μm. Then, the silicone wafer was baked on a hot plate at 100 ° C. for 120 seconds.

Then, exposure was performed using an excimer laser stepper (NSR 2005EX NA = 0.5, manufactured by Nikon Corporation), and baking was performed at 90 ° C. for 60 seconds to obtain 2.38%.
Development with an aqueous solution of tetramethylammonium hydroxide made it possible to obtain a positive pattern.

The obtained resist pattern is evaluated as follows.
I paid. First, the sensitivity (Eth value) was obtained. Next, 0.
35μm line and space top and bottom
The optimal exposure amount (sensitivity: E op)
As a separate line and
The minimum line width of the space was used as the resolution of the evaluation resist. Well
The shape of the resolved resist pattern is
It was observed with a microscope. Table 1 shows the results.

[0085]

Embedded image

[0086]

[Chemical 17]

[0087]

Embedded image

[0088]

[Table 1]

[Reference Example 2] The following formula (PA
G. 6 to 8) or a positive pattern was obtained in the same manner as in Reference Example 1 except that the above formula (PAG.4,5) was used, and the obtained resist pattern was evaluated as follows.

First, the sensitivity (Eth value) was determined. next,
0.35 μm line and space top and bottom
The optimum exposure amount (sensitivity: E o
p) as a separate liner at this exposure dose.
The minimum line width of the bond space is the resolution of the evaluation resist.
Was. The shape of the resolved resist pattern is a scanning type.
It was observed using an electron microscope. PED stability of resist
After performing the exposure with the optimum exposure amount, PEB is performed by changing the standing time.
The time when the change in the resist pattern shape was observed, eg
For example, the line pattern becomes T-top shape,
I evaluated it when I couldn't. The longer this time is PE
D High in stability. The results are shown in Table 2.

[0091]

[Chemical 19]

[0092]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Ishihara 28-1 Nishifukushima, Kubiki Village, Nakakubiki District, Niigata Prefecture Shin-Etsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A novel sulfonium salt represented by the following general formula (1). Embedded image (In the formula, R ₁ represents a hydrogen atom, an alkyl group or an alkoxy group, and Y represents trifluoromethanesulfonate or p-
Indicates toluene sulfonate. n is an integer of 0 to 2, m is an integer of 1 to 3, and n + m = 3. ) 2. The following general formula (2): (In the formula, R ₁ represents a hydrogen atom, an alkyl group or an alkoxy group, and Y represents trifluoromethanesulfonate or p-
Indicates toluene sulfonate. n is an integer of 0 to 2, m is an integer of 1 to 3, and n + m = 3. ) P-
The tert-butoxyphenylsulfonium salt is deprotected with a sulfonic acid represented by the following general formula (3) YH (3) (wherein Y has the same meaning as described above), and the following general formula (4) is obtained. [Chemical 3] (In the formula, R ₁ , Y, n, and m have the same meanings as described above.) After obtaining a p-hydroxyphenylsulfonium salt, the following general formula (5) XCH ₂ CO ₂ C ( _{CH 3) 3 ... (5)} ( wherein, X is a sulfonium salt according to claim 1, wherein the reacting α- haloacetic acid tert- butyl represented by a chlorine atom or a bromine atom.) Production method.