JP3399166B2 - Chemically amplified positive resist material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified positive resist material suitable for fine processing technology.

[0002]

2. Description of the Related Art LSI to be Solved
With the higher integration and higher speed, the finer pattern rules are required, and far-ultraviolet lithography is expected as a next-generation fine processing technology. The deep-UV lithography can also process 0.3 to 0.4 μm, and when a resist material having low light absorption is used, it is possible to form a pattern having a side wall that is nearly vertical to the substrate. Moreover, in recent years, KrF, which has a high brightness as a light source of far ultraviolet rays,
A technique using an excimer laser is drawing attention, and a resist material having low light absorption and high sensitivity is required for its use as a mass production technique.

From such a viewpoint, a chemically amplified positive resist material using an acid as a catalyst developed in recent years (Japanese Patent Publication No. 2-2
7660 and JP-A-63-27829) have high sensitivity, resolution and dry etching resistance, and have excellent characteristics, and are particularly promising resist materials for deep ultraviolet lithography.

In this case, in the chemically amplified positive resist material, it is known that the acid generator compounded has a particularly large effect on the function as the chemically amplified positive resist material. Typical examples of such an acid generator include the onium salts shown below.

[0005]

[Chemical 2]

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

However, in the case of a positive resist material, the decomposition product formed by absorbing the high energy rays by the acid generator is also oil-soluble, so that this decomposition product dissolves in the alkaline aqueous solution in the exposed area. It is impossible to reduce the speed and increase the alkali dissolution rate ratio (called dissolution contrast) between the exposed area and the unexposed area. Therefore, the chemically amplified positive resist material using the onium salt has low resolution in alkali development,
Due to the poor removal of the exposed portion, the pattern shape is not rectangular but has a trapezoidal forward taper.

In order to solve this problem, therefore, an tert-butoxy group, which is an acid labile group, is introduced at the p-position of the triphenylsulfonium salt and decomposed by irradiation with high-energy rays, resulting in the action of an acid to produce alkali solubility. It has been conducted to generate a phenol derivative having the formula (1) and increase the dissolution contrast (see JP-A-7-324069 ). However, even if a sulfonium salt that produces such a phenol derivative is used, it is difficult to obtain a satisfactory resolution when exposure is performed on a substrate having a low reflectance.

This is the above sulfonium salt of 250 nm
Since the transmittance in the vicinity is low and the transmittance as a resist film is reduced, the light intensity at the top and bottom of the resist film will differ when exposure is performed using a substrate with a low reflectance, and the amount of acid generated will differ. Appears, which is considered to reduce the resolution.

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 film surface is lowered, which is a major drawback in practical use. Due to this drawback, the conventional chemically amplified positive resist material has a problem that it is difficult to control the dimensions in the lithography process and the dimension control is impaired even when the substrate is processed using dry etching [Reference: W. Hinsberg, et. a
l. J. Photopolym. Sci. Techn
ol. , 6 (4), 535-546 (1993). ，
T. Kumada, et. al. J. 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 generated on the resist film surface by exposure reacts with a basic compound in the air to be inactivated, and the longer the standing time before PED, the more the amount of inactivated acid increases. Therefore, the acid labile group is decomposed. Is less likely to occur. Therefore, the insolubilized layer is formed on the surface, and the pattern has a T-top shape.

In this case, it is known that the addition of a basic compound can suppress the influence of the basic compound in the air, so that it is also effective for PED (Japanese Patent Laid-Open No. 232706/1993). However, according to the present inventors' investigation, the basic compound used here is not incorporated into the resist film due to volatilization, or has a compatibility with each component of the resist material. It was found that, since the dispersion in the resist film was not uniform, there was a problem in the reproducibility of the effect and the resolution was degraded.

Therefore, development of a high-performance chemically amplified positive resist material which does not have the above problems is desired.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a chemically amplified positive resist material having high resolution suitable for fine processing technology.

[0015]

Means and Actions for Solving the Problems As a result of earnest studies to achieve the above object, the present inventor has found that a diaryl sulfoxide represented by the following general formula (2) and the following general formula ( By reacting with a trialkylsilyl sulfonate represented by 3) and further reacting with a Grignard reagent represented by the following general formula (4), which can be prepared by a reaction of 3-tert-butoxyphenyl chloride and metallic magnesium, It was found that a novel sulfonium salt having a tert-butoxy group at the 3-position of the phenyl group represented by the general formula (1a) can be obtained. Further, te of the sulfonium salt represented by the following general formula (1a) is
The rt-butoxy group is deprotected with an acid, and te
By substituting the 3-position of the phenyl group with an acid labile group consisting of an rt-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a trialkylsilyl group, a tetrahydropyranyl group, a methoxymethyl group, etc. A novel sulfonium salt of the following formula (1) having at least one acid labile group is obtained, and the sulfonium salt of the above formula (1) is a chemically amplified positive type having a high resolution suitable for microfabrication technology. It has been found that it is suitable as a component of a resist material and can exert great power particularly in deep ultraviolet lithography.

[0016]

[Chemical 3] (In the formula, R ¹ is a hydrogen atom, an alkyl group, an alkoxy group or a dialkylamino group, OR ² is an acid labile group, and R ³ is a methyl group or a tert-butyl group.
Is a substituted or unsubstituted alkyl sulfonate or aryl sulfonate. n is an integer of 0 to 2, m is an integer of 1 to 3, and the sum of n and m is 3. )

That is, although the sulfonium salt of the above formula (1) of the present invention has a low alkali solubility of the compound itself, an acid produced by decomposition by irradiation with high energy rays, moisture in the resist material and PEB (Post Exposu).
re Bake) efficiently decomposes the acid labile group, resulting in a highly alkaline-soluble phenol moiety or tert.
In the case of having a tertiary carboxylic acid ester group such as -butoxycarbonylmethyloxy group, a carboxylic acid site is generated, so that a larger dissolution contrast can be obtained.

Therefore, the sulfonium salt of the above formula (1) can exhibit excellent performance as an acid generator of a chemically amplified positive resist material, and a resist material containing the sulfonium salt of the above formula (1) can be used. Has a large dissolution contrast due to the effect of the acid labile group of the sulfonium salt of the above formula (1), and particularly when a light source near 250 nm is used, the oxygen atom is in a position where it cannot form a resonance structure with the sulfur atom. By being substituted, the transmittance in the vicinity of 250 nm can be increased to a level equal to or higher than that of the non-substituted one, and therefore a resist image having high resolution and a wide depth of focus can be obtained.

That is, the present invention comprises (A) an acid generator containing a sulfonium salt represented by the following general formula (1) and having at least one acid labile group at the 3-position of the phenyl group in the molecule. And a chemically amplified positive resist material.

The present invention will be described in more detail below. The sulfonium salt contained as an acid generator in the chemically amplified positive resist composition of the present invention is represented by the following general formula (1) and has a phenyl group of a molecule. It has at least one acid labile group at the 3-position.

[0021]

[Chemical 4] (Wherein R ¹ is a hydrogen atom, an alkyl group, an alkoxy group or a dialkylamino group, OR ² is an acid labile group, Y is a substituted or unsubstituted alkyl sulfonate or aryl sulfonate, and n is n An integer from 0 to 2, m
Is an integer of 1 to 3, and the sum of n and m is 3. )

In the above formula (1), R ¹ is a hydrogen atom,
It is an alkyl group, an alkoxy group or a dialkylamino group, and specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and se.
A C1-butyl group, a tert-butyl group, a hexyl group, a cyclohexyl group and the like having 1 to 8 carbon atoms are preferable, and among them, a methyl group, an ethyl group, an isopropyl group, a tert- group.
A butyl group is more preferably used. Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, t.
An ert-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, a tert- group.
A butoxy group is more preferably used. As the dialkylamino group, a dimethylamino group, a diethylamino group,
An amino group having an alkyl group having 1 to 4 carbon atoms such as a dipropylamino group is used, and among them, a dimethylamino group is preferable.

OR ² is an acid labile group. Here, as the acid labile group, for example, a tertiary alkoxy group such as a tert-butoxy group, a carbonate ester group such as a tert-butoxycarbonyloxy group, a tertiary carboxylic acid ester group such as a tert-butoxycarbonylmethyloxy group, Trimethylsilyloxy group, triethylsilyloxy group, ter
Examples thereof include trialkylsilyloxy groups such as t-butyldimethylsilyloxy group, acetals and ketal groups such as tetrahydropyranyloxy group, methoxymethyloxy group, ethoxyethyloxy group and the like.

Y is a substituted or unsubstituted alkyl sulfonate or aryl sulfonate, for example, trifluoromethane sulfonate, nonafluorobutane sulfonate and p-toluene sulfonate are preferable. n
Is an integer of 0 to 2, m is an integer of 1 to 3, and the sum of n and m is 3.

In the present invention, when a sulfonium salt having a p-toluenesulfonate anion (p-toluenesulfonate) as a counter anion (Y ⁻ ) is used as a component of a resist material, the p-toluenesulfonate anion of the p-toluenesulfonate anion is used. The effect, that is, the effect of acid deactivation by the basic compound in the air on the resist film surface can be made very small, so that the formation of a surface-insoluble layer can be suppressed and the PED stability is good. Thus, the problem of the surface-insoluble layer, which is the cause of the T-top shape, that is, the problem of PED can be sufficiently solved, and a better sensitivity can be obtained.

Specific examples of the sulfonium salt of the above formula (1) are as follows. That is, as the sulfonium salt having a tert-butoxy group as an acid labile group, for example, trifluoromethanesulfonic acid (3-tert-butoxyphenyl) diphenylsulfonium, p-toluenesulfonic acid (3-tert-butoxyphenyl) diphenylsulfonium, Nonafluorobutane sulfonic acid (3-tert-butoxyphenyl)
Diphenylsulfonium, bis (3-tert-butoxyphenyl) phenylsulfonium trifluoromethanesulfonate, bis (3-ter) sulfonate p-toluenesulfonate
t-butoxyphenyl) phenylsulfonium, nonafluorobutanesulfonate bis (3-tert-butoxyphenyl) phenylsulfonium, trifluoromethanesulfonate tris (3-tert-butoxyphenyl)
Sulfonium, tris (3-t-p-toluenesulfonate)
ert-butoxyphenyl) sulfonium, tris (3-tert-butoxyphenyl) sulfonium nonafluorobutanesulfonate, trifluoromethanesulfonic acid (3-tert-butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium, p-toluenesulfonic acid (3-tert-butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium, nonafluorobutanesulfonic acid (3-tert-butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium, trifluoromethanesulfonic acid bis (3-tert) -Butoxyphenyl) (4-dimethylaminophenyl) sulfonium, bis (3-tert-butoxyphenyl) p-toluenesulfonate (4-dimethylaminophenyl) sulfonium, nonaf Oro butanoic acid bis (3-t
ert-butoxyphenyl) (4-dimethylaminophenyl) sulfonium and the like.

Examples of the sulfonium salt having a tert-butoxycarbonyloxy group as an acid labile group include bis (3-tert-butoxycarbonyloxyphenyl) phenylsulfonium trifluoromethanesulfonate, p
-Bis (3-tert-butoxycarbonyloxyphenyl) phenylsulfonium toluenesulfonate, tris (3-tert-butoxycarbonyloxyphenyl) sulfonium trifluoromethanesulfonate, tris (3-tert-butoxycarbonyloxyphenyl) p-toluenesulfonate ) Sulfonium, tris (3-tert-butoxycarbonyloxyphenyl) sulfonium nonafluorobutanesulfonate, (3-tert-butoxycarbonyloxyphenyl) bis (4-dimethylaminophenyl) sulfonium trifluoromethanesulfonate, p-toluenesulfonic acid (3-tert-Butoxycarbonyloxyphenyl) bis (4-dimethylaminophenyl) sulfonium, trifluoromethanesulfonic acid bis (3 tert-Butoxycarbonyloxyphenyl) (4-dimethylaminophenyl) sulfonium, bis (3-tert-butoxycarbonyloxyphenyl) (4-dimethylaminophenyl) sulfonium, bis (3-nonafluorobutanesulfonate) tert-butoxycarbonyloxyphenyl) (4-dimethylaminophenyl) sulfonium and the like.

As the sulfonium salt having a tert-butoxycarbonylmethyloxy group as an acid labile group,
Bis (3-tert-butoxycarbonylmethyloxyphenyl) phenylsulfonium trifluoromethanesulfonate, Bis (3-tert-toluenesulfonate)
-Butoxycarbonylmethyloxyphenyl) phenylsulfonium, trifluoromethanesulfonate tris (3-tert-butoxycarbonylmethyloxyphenyl) sulfonium, nonafluorobutanesulfonate tris (3-tert-butoxycarbonylmethyloxyphenyl) sulfonium, trifluoromethanesulfone Acid (3-tert-butoxycarbonylmethyloxyphenyl) bis (4-dimethylaminophenyl) sulfonium, p-toluenesulfonate bis (3-tert-butoxycarbonylmethyloxyphenyl) (4-dimethylaminophenyl) sulfonium and the like. To be

The sulfonium salt having an acetal or ketal group as an acid labile group is a bis (3- (2-tetrahydropyranyl) -oxyphenyl) phenylsulfonium trifluoromethanesulfonate having a tetrahydropyranyl group, Tris (3- (2-tetrahydropyranyl) -oxyphenyl) sulfonium trifluoromethanesulfonate, Tris (3- (2-tetrahydropyranyl) -oxyphenyl) sulfonium nonafluorobutanesulfonate, Trifluoromethanesulfonic acid (3- (2-Tetrahydropyranyl) -oxyphenyl) bis (4-dimethylaminophenyl) sulfonium, p-toluenesulfonate bis (3- (2-tetrahydropyranyl) -oxyphenyl) (4-dimethylaminophenyl) su Honiumu and the like, as having a methoxymethyl group, trifluoromethanesulfonic acid bis (3-methoxymethyl-oxyphenyl) phenyl trifluoromethanesulfonate, tris (3-methoxymethyl-oxyphenyl) sulfonium,
Tris (3-methoxymethyloxyphenyl) sulfonium nonafluorobutanesulfonate, (3-methoxymethyloxyphenyl) bis (4-dimethylaminophenyl) sulfonium trifluoromethanesulfonate, p-
Examples thereof include bis (3-methoxymethyloxyphenyl) (4-dimethylaminophenyl) sulfonium toluenesulfonate.

Examples of the sulfonium salt having a trialkylsilyloxy group as the acid labile group include bis (3-trimethylsilyloxyphenyl) phenylsulfonium trifluoromethanesulfonate and bis (3-triethylsilyloxyphenyl) phenyl p-toluenesulfonate. Sulfonium, trifluoromethanesulfonate tris (3
-Trimethylsilyloxyphenyl) sulfonium, tris (3-trimethylsilyloxyphenyl) sulfonium nonafluorobutanesulfonate, trifluoromethanesulfonic acid (3-triethylsilyloxyphenyl)
Bis (4-dimethylaminophenyl) sulfonium, p
-Bis (3-trimethylsilyloxyphenyl) (4-dimethylaminophenyl) sulfonium toluenesulfonate and the like.

The sulfonium salt of the above formula (1) of the present invention can be synthesized by the following route. That is, for example, a 3-halogen represented by the following general formula (7) obtained by first condensing a 3-halogenated phenol represented by the following general formula (5) and an isobutene represented by the following general formula (6) with an acid. -Tert-Butoxybenzene is reacted with metallic magnesium in THF by a conventional method to give 3-tert-butoxyphenyl Grignard (Grignear reagent) represented by the following general formula (4). Next, a sulfoxide represented by the following general formula (2) is reacted with a trialkylsilyl sulfonate represented by the following general formula (3) in an organic solvent, and further reacted with a Grignard reagent represented by the following formula (4): A sulfonium salt having a 3-tert-butoxyphenyl group as the acid labile group represented by the following general formula (1a) can be synthesized.

[0032]

[Chemical 5] (However, in the formula, R ¹ , R ² , R ³ , Y, m, and n are the same as described above, and X is a bromine atom or a chlorine atom.)

In the above reaction, the reaction between the 3-halogenated phenol of the above formula (5) and the isobutene of the above formula (6) is described in "Experimental Chemistry Lecture 4th Edition, Organic Synthesis 2, p200, edited by The Chemical Society of Japan, Maruzen." And “J. Holcombe and
T. Livinghouse J. Org. Che
m. , 111-115.51. (1986) ”. In this case, when the 3-halogenated phenol of the formula (5) is reacted with the isobutene of the formula (6), the isobutene of the formula (6) is 1 to 1 relative to the 3-halogenated phenol of the formula (5). 10 mol, particularly 3 to 5 mol, and 0.01 to 0.1 mol, particularly 0.01 to 0.1 mol, relative to the 3-halogenated phenol of the formula (5) using a strong acid such as trifluoromethanesulfonic acid as a catalyst. 0.05
This is preferably added in molar proportions. The reaction is preferably carried out in an organic solvent such as methylene chloride in the temperature range of -40 to -70 ° C for 0.5 to 4 hours.

As the sulfoxide of the above formula (2), diphenyl sulfoxide, bis (3,4-di-tert-butoxyphenyl) sulfoxide represented by the following formula (2a), and bis represented by the following formula (2b). (4-te
rt-butoxyphenyl) sulfoxide, represented by the following formula (2
bis (4-dimethylaminophenyl) sulfoxide represented by c) and bis (3-tert-butoxyphenyl) sulfoxide represented by the following formula (2d), which is a condensation product of the Grignard reagent of the above formula (4) and thionyl chloride. It is desirable to use

[0035]

[Chemical 6]

The synthesis of these sulfoxide compounds is
It can be carried out according to the method described in JP-A-7-215930 .

For example, when the compound of the above formula (2b) is obtained, it can be carried out by a method of reacting p-tert-butoxyphenyl grignia represented by the following formula (A) with thionyl chloride.

[0038]

[Chemical 7] (X represents a chlorine or bromine atom.)

In this case, the reaction is preferably carried out in an organic solvent such as methylene chloride or THF. When the Grignard reagent is reacted with thionyl chloride, thionyl chloride is added to the Grignard reagent in an amount of 1/6 to 1/2 mol, preferably 1/30 mol.
The reaction condition is -78 ° C
The temperature is 70 ° C, preferably -60 ° C to 10 ° C, and the dropping time is 10 to 120 minutes, preferably 45 to 90 minutes. After the completion of the reaction, the solvent layer is washed with water, dried and concentrated, and then the target compound can be obtained by recrystallization or column chromatography.

In the present invention, the above formulas (2a), (2b),
A novel sulfonium salt having one 3-tert-butoxyphenyl group can be synthesized by using (2c) or a sulfoxide such as diphenyl sulfoxide as a raw material. Moreover, a novel sulfonium salt having three 3-tert-butoxyphenyl groups can be synthesized by using the sulfoxide of the above formula (2d) as a raw material.

A novel sulfonium salt having two 3-tert-butoxyphenyl groups is a bis (3-tert-butoxyphenyl) sulfoxide of the above formula (2d) and an arylglycol represented by the following formula (8). It can be synthesized by reacting with a Niya reagent, for example, phenyl Grignard, 4-tert-butoxyphenyl Grignard, 4-dimethylaminophenyl Grignard and the like.

[0042]

[Chemical 8] (In the above formula, R ¹ , R ³ , Y, X, m and n are the same as above.)

When a sulfoxide having the tert-butoxy group at the 2-position and the 2'-position such as bis (2,4-di-tert-butoxyphenyl) sulfoxide is used as the sulfoxide of the above formula (2), The target compound cannot be obtained due to steric hindrance. The same applies when a compound having a tetrahydropyranyloxy group at the 2-position and 2'-position is used.

In the prior art method for synthesizing a sulfonium salt or sulfoxide compound by the reaction of phenol or anisole with thionyl chloride, the active site of phenol has two ortho and para positions. , Para-substitution may be different, especially meta-substitution cannot be obtained. Furthermore, in this reaction, since hydrogen chloride gas is generated in the reaction system, tert
-It is difficult to synthesize a compound having an acid labile group such as butoxybenzene as a raw material. On the other hand, in the method of the present invention, since the Grignard reagent is used, only the meta-substituted product can be quantitatively obtained, and an inorganic salt such as magnesium chloride is generated instead of hydrogen chloride gas. The decomposition of the stable group does not proceed.

In the above synthetic method, 3-tert
-Butoxyphenyl Grignard reagent was used as a raw material for sulfoxide and sulfonium salt, but the protecting group which is inert to Grignard reagent and can be removed by an acid, for example, tetrahydropyranyl group protects the hydroxyl group of 3-halogenated phenol. The sulfonium salt of the above formula (1) can also be synthesized by using a Grignard reagent prepared by reacting with magnesium metal.

In the above reaction, it is preferable to mix the trialkylsilyl sulfonate of the above formula (3) with the sulfoxide of the above formula (2) in an amount of 1 to 5 mol, particularly 2 to 3 mol, Further, it is preferable to add the Grignard reagent of the above formula (4) or the above formula (8) in an amount of 1 to 5 mol, particularly 2 to 3 mol, relative to the sulfoxide of the above formula (2). Furthermore, these reactions prevent elimination of the tert-butoxy group by a slight amount of acidic impurities present in the trialkylsilyl sulfonate of the above formula (3),
In the presence of an organic base such as triethylamine or pyridine, T
It is desirable to carry out in an organic solvent such as HF or methylene chloride. The reaction conditions for these reactions are not particularly limited, but a reaction temperature of 0 to 10 ° C is preferable.

Further, in the present invention, the tert-butoxy group of the sulfonium salt of the above formula (1a) is deprotected with an acid,
The hydrogen atom of the phenolic hydroxyl group is tert-
By substituting an acid labile group such as a butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a trialkylsilyl group, a tetrahydropyranyl group, and a methoxymethyl group, the target acid labile group is converted to the 3-position of the phenyl group. A novel sulfonium salt represented by the following general formula (1) can be obtained.

[0048]

[Chemical 9] (However, in the above formula, R ¹ , R ² , Y, n, and m are the same as above.)

The chemically amplified positive resist material of the present invention is
A chemical amplification positive type resist containing a sulfonium salt represented by the above formula (1) as an acid generator, which is a three- component system (organic solvent, alkali-soluble resin, acid generator, dissolution inhibitor). it is preferable to have use as a material.

Specific embodiments of the chemically amplified positive type resist material of the present invention are as follows. [I] (A) organic solvent, (B) alkali-soluble resin, (C) dissolution inhibitor having acid labile group, (D) sulfonium salt represented by general formula (1), (E) acid generator A chemically amplified positive resist material containing. [II] (A) organic solvent, (B) alkali-soluble resin, (C) dissolution inhibitor having acid labile group, (D) sulfonium salt represented by general formula (1), (F) general formula Onium salt represented by (9) (R ⁴ ) _a MY (9) (wherein R ⁴ is the same or different substituted or unsubstituted aromatic group, M is iodonium or sulfonium, Y is substituted or non-substituted) A chemically amplified positive resist composition containing a substituted alkyl sulfonate or aryl sulfonate, wherein a is 2 or 3.). [III] (A) an organic solvent, (B) an alkali-soluble resin, (C) a dissolution inhibitor having an acid labile group, and (D) a sulfonium salt represented by the general formula (1). Chemically amplified positive resist material. [IV] A chemically amplified positive resist material containing (A) an organic solvent, (B) an alkali-soluble resin, and (D) a sulfonium salt represented by the general formula (1) .

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, diethylene glycol Ethers such as dimethyl ether,
Propylene glycol monomethyl ether acetate,
Propylene glycol monoethyl ether acetate,
Ethyl lactate, ethyl pyruvate, butyl acetate, methyl-
Examples thereof include esters such as 3-methoxypropionate and ethyl-3-ethoxypropionate, and one of these can be used alone or in combination of two or more. Among these, 1-ethoxy-2-propanol, which has the highest solubility of the acid generator in the resist component, is preferably used.

As the alkali-soluble resin of the component (B) which is the base resin, polyhydroxystyrene or its derivative can be mentioned. As the derivative of polyhydroxystyrene, one obtained by partially replacing the hydrogen atom of the hydroxyl group of polysidoxystyrene with an acid labile group is preferable, but a copolymer of hydroxystyrene can also be used. In the former case, the acid labile group is ter
t-butyl group, tert-butoxycarbonyl group, tetrahydropyranyl group, methoxymethyl group, trimethylsilyl group, tert-butyldimethylsilyl group and the like, tert-butyl group, tert-butoxycarbonyl group, tetrahydropyranyl group It is preferably used.
In the latter case, the hydroxystyrene copolymer is
Copolymer of hydroxystyrene and styrene, Copolymer of hydroxystyrene and -tert-butyl acrylate, Copolymer of hydroxystyrene and tert-butyl methacrylate, Copolymer of hydroxystyrene and maleic anhydride Examples thereof include a copolymer and a copolymer of hydroxystyrene and di-tert-butyl maleate.

The weight average molecular weight of polyhydroxystyrene or its derivative is 5,000 to 100,000.
It is preferably 0, and if it is less than 5,000, the film forming property and resolution may be inferior, and if it exceeds 100,000, the resolution may be inferior.

In the present invention, the sulfonium salt of the above formula (1) is blended as the component (D), but if necessary, other acid generators as the (E) component other than the sulfonium salt of the above formula (1). Can also be compounded. 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-
N-sulfonyloxyimide derivatives such as 1,3,5-triazine derivative, aryl sulfonate ester derivative, pyrogallol sulfonate ester derivative, N-trifluoromethanesulfonyloxyphthalide, N-trifluoromethanesulfonyloxynaphthalide, α, α '-
Examples thereof include bisarylsulfonyldiazomethane derivatives, and particularly, the following general formula (9) (R ⁴ ) _a MY ... (9) (wherein, R ⁴ is the same or different substituted or unsubstituted aromatic group, and M is Iodonium or sulfonium, Y is a substituted or unsubstituted alkyl sulfonate or aryl sulfonate, and a is 2 or 3).

Here, as R ⁴ in the above formula (9),
For example, an aromatic group such as a phenyl group or a phenyl group substituted with an alkyl group or an alkoxy group similar to the above formula (1) is preferably used. Specific examples of the onium salt of the above formula (9) include compounds having the following structures.

[0056]

[Chemical 10]

Further, as the dissolution inhibitor of the component (C),
One or more acid-labile groups in the molecule (acid-labile groups)
A low molecular weight compound or polymer having is preferred. Specific examples of the low molecular weight compound include bisphenol A derivatives and carbonic acid ester derivatives. Particularly, the hydroxyl group of bisphenol A is tert-butoxy group or tert-butoxy group.
Compounds substituted with a butoxycarbonyloxy group are preferred.

Examples of polymer dissolution inhibitors include p-
Examples thereof include a copolymer of tert-butoxystyrene and tert-butyl acrylate and a copolymer of p-tert-butoxystyrene and maleic anhydride. In this case, the weight average molecular weight is preferably 5,000 to 10,000.

The three-component chemically amplified positive resist composition of the present invention contains 150 to 700 parts (parts by weight, the same applies hereinafter) of the organic solvent as the component (A), particularly 250 to 500 parts, and an alkali-soluble component as the component (B). 70-90 parts of resin, especially 75-85
It is preferable to add 5 parts of a dissolution inhibitor having an acid labile group as the component (C) in addition to the above components.
It is preferable to add 40 parts, especially 10 to 25 parts .

Further, the blending amount of the sulfonium salt of the above formula (1) as the component (D) is 0.5 to 15 parts, especially 2 to
It is preferably 8 parts, and if less than 0.5 part, the acid generation amount during exposure may be small and sensitivity and resolution may be poor, and if it exceeds 15 parts, the transmittance of the resist may be lowered and resolution may be poor. There is.

In addition to the sulfonium salt of the above formula (1), if necessary, as the component (E), another acid generator is blended, the component (E) is added in an amount of 0.5 to 15
It is preferable that the range is from 2 to 8 parts.

To the above resist material, an additive such as a nitrogen-containing compound for PED stability, a surfactant for improving coatability, and a light absorbing material for reducing irregular reflection from the substrate should be added. You can

The nitrogen-containing compound is preferably an amine compound or an amide compound having a boiling point of 150 ° C. or higher, and specific examples thereof include aniline, N-methylaniline, N, N-dimethylaniline, o-toluidine and 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-amino Benzoic acid, p-aminobenzoic acid, 1,
2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2-quinolinecarboxylic acid, 2-amino-4-nitrophenol, 2- (p-
And triazine compounds such as chlorophenyl) -4,6-trichloromethyl-s-triazine. Among these, pyrrolidone, N-methylpyrrolidone, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine. Is preferably used. The compounding amount of the nitrogen-containing compound in the resist material of the present invention is preferably 0.05 to 4 parts, particularly preferably 0.1 to 1 part.

Further, examples of the surfactant include perfluoroalkyl polyoxyethylene ethanol, fluorinated alkyl ester, perfluoroamine 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. Particularly, the resist material is 254 to 193 nm.
Most suitable for fine patterning with far-ultraviolet light and electron beam.

[0067]

INDUSTRIAL APPLICABILITY The novel sulfonium salt of the above formula (1) according to the present invention has an acid labile group introduced at the 3-position of the phenyl group of the sulfonium salt which is an acid generator. The dissolution contrast of the part can be increased, and by introducing an oxygen atom at the 3-position so that the resonance structure of the sulfur atom cannot be taken, the transmission around 250 nm is equal to or higher than that of the unsubstituted triphenylphosphonium salt. The ratio can be increased, and as a result, the transmittance as a resist material can be increased, so that it is effective as a component of a chemically amplified positive resist material having high resolution suitable for a microfabrication technique. Therefore, a resist material containing the sulfonium salt of the above formula (1) of the present invention as an acid generator is
Far-ultraviolet rays, electron beams, as chemically amplified positive resist materials,
It has high sensitivity to high-energy rays such as X-rays, especially KrF excimer laser, and can form patterns by developing with an alkaline aqueous solution. It has excellent sensitivity, resolution, and plasma etching resistance, and also has heat resistance of resist patterns. Are better.

[0068]

EXAMPLES The present invention will be specifically described below by showing synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples. All parts in each example are parts by weight.

Synthesis Example 1 Trifluoromethanesulfonic acid tris (3-tert-)
Synthesis of butoxyphenyl) sulfonium 17.8 g (0.052 mol) of bis (3-tert-butoxyphenyl) sulfoxide was dissolved in 52 g of THF and cooled in an ice water bath. To this was added 5.3 g (0.052 mol) of triethylamine, and 28.6 g (0.1% of trimethylsilyltrifluoromethanesulfonate) was added.
(3 mol) was added dropwise while controlling so as not to exceed 10 ° C, and the reaction temperature was adjusted to 0 to 10 ° C to ripen the reaction. 24.0 g (0.13 mol) of 3-tert-butoxychlorobenzene, 3.2 g (0.13 mol) of metallic magnesium, and 40 g of THF were used in this solution to control a Grignard reagent prepared by a conventional method so as not to exceed 10 ° C. While dripping. Further, the reaction temperature is 0 to
The reaction was aged at 10 ° C. for 30 minutes. 2 in the reaction solution
After stopping the reaction and performing liquid separation by adding 300 g of a 0% ammonium chloride aqueous solution, 300 g of chloroform was added to the organic layer. After washing the organic layer twice with 200 g of water,
The solvent was distilled off under reduced pressure to obtain an oily substance. When this oily substance was subjected to column chromatography (silica gel: extract, chloroform-methanol), tris (3-tert-butoxyphenyl) sulfonium trifluoromethanesulfonate having a yield of 10.5 g (yield 29%) and a purity of 99% was obtained. Was isolated.

Nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR), elemental analysis value and ultraviolet absorption spectrum (UV) of the obtained tris (3-tert-butoxyphenyl) sulfonium trifluoromethanesulfonate.
The results are shown below. For comparison, the values of ultraviolet absorption spectra of triphenylsulfonium trifluoromethanesulfonate and tris (4-tert-butoxyphenyl) sulfonium trifluoromethanesulfonate are also shown.

[0071]

[Chemical 11] (A) 1.25 singlet 27H (b) 7.05 to 7.06 triplet 3H (c), (e) 7.25 to 7.29 multiplet 6H (d) 7.51 to 7.57 triplet Item 3H IR: (cm ⁻¹ ) 2980, 1587, 1564, 1477, 1423
1394, 1369, 1263, 1259, 1159,
1031, 933, 912, 638. Elemental analysis value: (%) C ₃₁ H ₃₉ O ₆ S ₂ F ₃ theoretical value C: 59.2 H: 6.2 analysis value C: 59.1 H: 6.1

[0072]

[Table 1]

[Synthesis Example 2] A reaction was conducted in the same manner as in Synthesis Example 1 except that phenyl Grignard was used in place of 3-tert-butoxyphenyl Grignard of Synthesis Example 1, and trifluoromethanesulfonic acid bis (3 -Tert
-Butoxyphenyl) phenylsulfonium has a purity of 98
%, The yield was 35%.

[Synthesis Example 3] Synthesis Example 1 except that diphenyl sulfoxide is used instead of the sulfoxide of Synthesis Example 1
When the reaction was carried out in the same manner as in (3), (3-tert-butoxyphenyl) diphenylsulfonium trifluoromethanesulfonate was obtained with a purity of 98% and a yield of 27%.

[Synthesis Example 4] A reaction was performed in the same manner as in Synthesis Example 1 except that bis (4-dimethylaminophenyl) sulfoxide was used instead of the sulfoxide of Synthesis Example 1, and trifluoromethanesulfonic acid (3-tert −
Butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium was obtained with a purity of 98% and a yield of 27%.

[Synthesis Example 5] A reaction was performed in the same manner as in Synthesis Example 1 except that 4-dimethylaminophenyl Grignard was used instead of the Grignard reagent of Synthesis Example 1, and trifluoromethanesulfonic acid bis (3-tert. -Butoxyphenyl) (4-dimethylaminophenyl) sulfonium was obtained with a purity of 98% and a yield of 33%.

[Synthesis Examples 6 to 10] Trimethylsilyl-p-toluenesulfonate obtained by reacting p-toluenesulfonic acid with trimethylsilylchloride by a conventional method in place of the trimethylsilyltrifluoromethanesulfonate used in Synthesis Examples 1 to 5 (Boiling point 113-1
The reaction was performed in the same manner as in Synthesis Examples 1 to 5 except that (17 ° C./0.5 to 0.6 mmHg) was used, whereby sulfonium salts having the following counter anions with p-toluenesulfonic acid were obtained. . Synthesis Example 6: p-toluenesulfonic acid tris (3-ter)
t-Butoxyphenyl) sulfonium Purity 99% Yield 35% Synthesis Example 7: Bis (3-tert-p-toluenesulfonate)
-Butoxyphenyl) phenylsulfonium Purity 99
% Yield 28% Synthesis Example 8: p-Toluenesulfonic acid (3-tert-butoxyphenyl) diphenylsulfonium Purity 99%
Yield 25% Synthesis example 9: p-toluenesulfonic acid (3-tert-butoxyphenyl) bis (4-dimethylaminophenyl)
Sulfonium Purity 97% Yield 31% Synthesis Example 10: Bis (3-ter) p-toluenesulfonate
t-Butoxyphenyl) (4-dimethylaminophenyl) sulfonium Purity 98% Yield 32%

[Synthesis Examples 11 to 15] Instead of the trimethylsilyltrifluoromethanesulfonate used in Synthesis Examples 1 to 5, trimethylsilylnonafluorobutanesulfonate obtained by reacting nonafluorobutanesulfonic acid and trimethylsilylchloride by a conventional method was used. The reaction was performed in the same manner as in Synthesis Examples 1 to 5 except that the sulfonium salt having nonafluorobutanesulfonic acid as the counter anion was obtained as follows. Synthesis Example 11: Tris (3) nonafluorobutane sulfonate
-Tert-butoxyphenyl) sulfonium Purity 9
9% Yield 31% Synthesis Example 12: Bis (3- (3) -nonafluorobutane sulfonate
tert-butoxyphenyl) phenylsulfonium
Purity 99% Yield 28% Synthesis Example 13: Nonafluorobutanesulfonic acid (3-te
rt-Butoxyphenyl) diphenylsulfonium Purity 99% Yield 18% Synthesis Example 14: Nonafluorobutanesulfonic acid (3-te
rt-Butoxyphenyl) bis (4-dimethylaminophenyl) sulfonium Purity 98% Yield 27% Synthesis Example 15: Bis (3-nonafluorobutanesulfonate)
tert-Butoxyphenyl) (4-dimethylaminophenyl) sulfonium Purity 97% Yield 25%

[Synthesis Examples 16 to 19] The novel sulfonium salt having the tert-butoxy group at the 3-position obtained in Synthesis Examples 1 to 15 was replaced with the same sulfonic acid as the counter anion (eg, trifluoromethanesulfonate or p-toluenesulfonate). After deprotecting in methanol or ethanol using the compound to obtain the corresponding 3-hydroxyphenylsulfonium salt almost quantitatively, di-tert-butyl-dicarbonate, chloroacetate-tert-butyl, or dihydropyran was obtained by a conventional method. By using it, a sulfonium salt having an acid labile group as shown below at the 3-position of the phenyl group was synthesized. Example 16: Bis (3) nonalifluorobutane sulfonate
-Tert-Butoxycarbonyloxyphenyl) phenylsulfonium Purity 98%, Yield 23% Example 17: Trifluoromethanesulfonic acid (3-te
rt-Butoxycarbonylmethyloxyphenyl) diphenylsulfonium Purity 98%, Yield 25% Example 18: p-toluenesulfonic acid (3-tert-
Butoxycarbonyloxyphenyl) diphenylsulfonium Purity 98%, Yield 19% Example 19: Tris (3) nonafluorobutanesulfonate
-Tert-Butoxycarbonylmethyloxyphenyl) sulfonium Purity 98%, Yield 18%

The 3-position substitution products (3-tert-butoxyphenylsulfonium salts) of the novel sulfonium salts of the above-mentioned Synthesis Examples 1 to 10 and 4-position substitution products (4-te) as comparative products.
rt-butoxyphenylsulfonium salt) 248 nm
Table 2 shows the molar extinction coefficient of the ultraviolet absorption spectrum in.

As is clear from the results shown in Table 2, the sulfonium salt of the present invention has a tert-butoxy group at the 3-position rather than at the 4-position, so that light absorption at 248 nm can be reduced, and the effect is tert-butoxy. It was found that tris (tert-butoxyphenyl) sulfonium salt having a large number of -butoxyphenyl groups appeared most.

[0082]

[Table 2]

[Examples 1 to 14, Comparative Examples 1 to 4] Table 3,
4, a polyhydroxystyrene represented by the following formula (Polym.1) in which a hydrogen atom of a hydroxyl group is partially protected by a tert-butoxycarbonyl group, the following formula (Po
lym. 2) The partial hydrogen atom of the hydroxyl group represented by
from polyhydroxystyrene protected by an ert-butyl group or polyhydroxystyrene in which hydrogen atoms of a partial hydroxyl group represented by the following formula (Polym.3) are protected by a tetrahydropyranyl group and from the following formula (PAG.1) ( PA
G. 5) an acid generator selected from the onium salts represented by the formula 5) and 2,2′-bis (4-tert-butoxycarbonyloxyphenyl) represented by the following formula (DRI.1).
A propane dissolution inhibitor was dissolved in 1-ethoxy-2-propanol to prepare resist compositions having various compositions shown in Tables 3 and 4.

A resist solution was prepared by filtering the obtained resist composition through a 0.2 μm Teflon filter, and then the resist solution was spin-coated on a silicone wafer and applied to a thickness of 0.8 μm.

Then, this silicone wafer is treated with 100
Baking was performed on a hot plate at ℃ for 120 seconds. Furthermore, excimer laser stepper (Nikon, NSR2005
Exposure was performed using EXNA = 0.5), baking was performed at 90 ° C. for 60 seconds, and development was performed with a 2.38% tetramethylammonium hydroxide aqueous solution, whereby a positive pattern could be obtained.

The obtained resist pattern was evaluated as follows. The results are shown in Tables 3 and 4. Resist pattern evaluation method : First, the sensitivity (Eth) was determined. Next, the exposure amount for resolving the top and bottom of a line and space of 0.35 μm at a ratio of 1: 1 is set as the optimum exposure amount (sensitivity: Eop), and the minimum line width of the separated line and space in this exposure amount is set. Was used as the resolution of the evaluation resist. The shape of the resolved resist pattern was observed using a scanning electron microscope.

[0087]

[Chemical 12]

[0088]

[Chemical 13]

[0089]

[Table 3]

[0090]

[Table 4]

[Examples 15 to 28, Comparative Examples 5 to 8] As shown in Tables 5 and 6, the following (PAG.
8) or a positive pattern was obtained in the same manner as in Example 1 except that (PAG4,5) described above was used. In addition, in Example 28, a nitrogen-containing compound for PED stability was added as an additive.

The obtained resist pattern was evaluated in the same manner as above. Further, the PED stability of the resist is determined by performing PEB after changing the standing time after exposure with the optimum exposure amount, and the time when the change of the resist pattern shape is observed, for example, the line pattern becomes T-top, and the resolution can be resolved. It was evaluated by the time when it disappeared. The longer this time, the better the PED stability. The above results are shown in Tables 5 and 6.

[0093]

[Chemical 14]

[0094]

[Table 5]

[0095]

[Table 6]

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuya Takemura Niigata Nakakubiki-gun Kubiki-mura 28-1 Nishifukushima Shin-Etsu Chemical Co., Ltd.Synthetic Technology Research Institute (72) Inventor Satoshi Watanabe Kubiki-mura, Niigata Prefecture 28-1 Nishi-Fukushima 28-1 Shin-Etsu Chemical Co., Ltd., Synthetic Technology Research Center (72) Inventor Toshinobu Ishihara Niigata Prefecture Nakakubiki-gun Kubiki-mura 28-1 Nishi-Fukushima Shin-Etsu Chemical Co., Ltd. Synthetic Technology Research Center (72) Inventor Nagura Shigehiro 28-1 Nishifukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture Shin-Etsu Chemical Co., Ltd.Synthesis Technology Research Center (72) Inventor Keijun Tanaka 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo (72) ) Inventor Yoshio Kawai 1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Jiro Nakamura Tokyo 1-6-1, Uchisaiwaicho, Chiyoda-ku, Nippon Telegraph and Telephone Corporation (56) Reference JP-A-6-287174 (JP, A) JP-A-4-219757 (JP, A) JP-A-4-215662 ( JP, A) JP 2-177031 (JP, A) JP 7-333834 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (6)

(57) [Claims] 1. A chemically amplified positive resist which is represented by the following general formula (1) and comprises a sulfonium salt having at least one acid labile group at the 3-position of the phenyl group in the molecule. material. [Chemical 1] (Wherein R ¹ is a hydrogen atom, an alkyl group, an alkoxy group or a dialkylamino group, OR ² is an acid labile group, Y is a substituted or unsubstituted alkyl sulfonate or aryl sulfonate, and n is n An integer from 0 to 2, m
Is an integer of 1 to 3, and the sum of n and m is 3. ) 2. A sulfonium salt is obtained by reacting a sulfoxide represented by the following general formula (2) with a trialkylsilyl sulfonate represented by the following general formula (3), and further reacting with a Grignard reagent represented by the following formula (4). As an acid labile group represented by the following general formula (1a)
The chemically amplified positive resist composition according to claim 1, which is a sulfonium salt having a -tert-butoxyphenyl group. [Chemical 15] (However, in the formula, R ¹ , Y, m, and n are the same as described above, and R ³ is a methyl group or a tert-butyl group,
X is a bromine atom or a chlorine atom. ) 3. A sulfonium salt is the compound of formula (1a) according to claim 2, wherein —OC (CH ₃ ) ₃ is —OH, and then this hydrogen atom is R ² (R ² is the same as above. ) Is obtained by substitution with
The chemically amplified positive type resist material described. 4. The chemically amplified positive resist material according to claim 1, 2 or 3, wherein the chemically amplified positive resist material is a three-component system. 5. (A) Organic solvent, (B) Alkali-soluble resin, (C) Dissolution inhibitor having acid labile group, (D) Sulfonium salt according to claim 1, 2 or 3, (E) Acid A chemically amplified positive resist material containing a generator. 6. A polyhydroxystyrene having a weight average molecular weight of 5,000 to 100,000 in which hydrogen atoms of some hydroxyl groups are substituted with acid labile groups is used as the alkali-soluble resin as the component (B). Item 5. A resist material according to item 5.