JPH09281704A - Positive type resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist compsn. ensuring slight variation in film thickness. SOLUTION: In this positive type resist compsn. contg. alkali-soluble phenolic resin, a quinonediazidosulfonic ester sensitizer and polyhydroxybenzene, the alkali-soluble phenolic resin is novolak resin obtd. by condensing one or more kinds of phenols and one or more kinds of aldehydes or ketones and at least one of the phenols is a phenolic compd. having two or more alkyl groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist composition, and more particularly to a positive resist composition for fine processing required for manufacturing semiconductor devices, magnetic bubble memory devices, integrated circuits and the like.

[0002]

2. Description of the Related Art As a resist composition for forming a semiconductor device, a positive resist composition has recently become mainstream. This is because the negative resist composition has high sensitivity, but has a difficulty in resolution because of swelling because an organic solvent is used for development, and the positive resist composition has excellent resolution. Therefore, it is considered that it is possible to sufficiently cope with high integration of semiconductors. This positive resist composition does not swell because it is developed with an aqueous alkali solution, and is excellent in resolution. The resolution of such a positive resist composition has been further improved by improving the performance of the positive resist composition itself and the performance of an exposure machine, and it has become possible to form a fine pattern of 1 μm or less.

Such resist compositions usually contain an alkali-soluble phenolic resin and a quinonediazide sulfonic acid type photosensitive compound, and these resist compositions have insufficient solubility of the photosensitive compound in a solvent. However, precipitation of foreign matter has been a problem due to long-term storage.
JP-A-2-13953 discloses that precipitation is prevented by adding polyhydroxybenzenes, particularly when the photosensitive compound is polyhydroxybenzophenones. On the other hand, as an alkali-soluble phenol resin for a positive resist composition, a novolac resin obtained by condensing phenols and aldehydes has been generally used so far, but it has excellent sensitivity, residual film rate, and
In order to obtain various characteristics such as resolution, heat resistance and storage stability, various combinations of phenols and aldehydes are being studied. Under such circumstances, when xylenol or the like is used as a phenol compound, the sensitivity and the residual film rate are simultaneously improved (Japanese Patent Publication No. 2-51499), and a resin having a specific molecular weight distribution using xylenol or trimethylphenol is used. When used, a resist having excellent resolution and dry etching resistance can be obtained (Japanese Patent Publication No. 7-68).
No. 435) and the like are known. However, when such a resin is used, the viscosity may increase due to long-term storage, and the increase in viscosity has a great influence on the film thickness,
It was an obstacle to the formation of fine patterns.

[0004]

Under the above-mentioned conventional techniques, the inventors of the present invention have made earnest studies to obtain a resist composition having a small change in film thickness, and as a result, a phenol compound having an alkyl group as a substituent is used as a raw material. By adding polyhydroxybenzenes to the resist composition using the alkali-soluble phenolic resin, it was found that the increase in viscosity of the resist composition can be suppressed, and the present invention has been completed.

[0005]

Thus, according to the present invention, in a positive resist composition containing an alkali-soluble phenol resin, a quinonediazide sulfonic acid ester-based photosensitizer, and polyhydroxybenzenes, the alkali-soluble phenol resin is A novolac resin obtained by condensation of one or more phenols with one or more aldehydes or ketones, wherein at least one phenol is a phenol compound having two or more alkyl groups. A positive resist composition is provided.

The present invention will be described in detail below. (A) Alkali-soluble phenol resin In the present invention, the alkali-soluble phenol resin is 2
It is obtained by condensation reaction of at least two kinds of phenol compounds with aldehydes or ketones in the presence of an acid catalyst, and in particular, one or more kinds of phenol compounds having two or more alkyl groups are used as the phenol compound. (Hereinafter, it may be simply referred to as a phenol compound). The alkali-soluble phenol resin may be used in combination with such a phenol compound having two or more alkyl groups and a phenol compound having one or less alkyl groups (hereinafter referred to as other phenol compound).

Specific examples of the phenol compound having two or more alkyl groups used here include 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol and 2 ，
Dimethylphenols such as 4-dimethylphenol and 2,6-dimethylphenol; 2,3,6-trimethylphenol and trimethylphenols; branched alkyl groups such as 2-t-butyl-5-methylphenol, thymol and isothymol Disubstituted phenols having
Phenol compounds having 2 or more lower alkyl groups having 1 to 4 carbon atoms are exemplified, and among them, dimethylphenols and trimethylphenols are preferable, and 2,5-dimethylphenol, 3,5-dimethylphenol and 2,
3,5-Trimethylphenol is a particularly preferred example. These may be used alone or in combination of two or more.

As other phenol compounds, phenol, o-cresol, m-cresol, p-cresol and the like can be used, and it is particularly preferable to use m-cresol and p-cresol. The ratio (molar ratio) of the phenol compound to other phenol compounds is 8
0: 20-0: 100, preferably 70: 30-20:
It can be arbitrarily set at about 80, but if it is out of this range, the effect of the present invention may not be sufficiently obtained.

Specific examples of aldehydes include formalin, paraformaldehyde, trioxane, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde,
p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde,
Examples thereof include o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, and terephthalaldehyde. Of these, formalin, paraformaldehyde, acetaldehyde and o-hydroxybenzaldehyde are preferable. These compounds may be used alone or in combination of two or more. Specific examples of ketones include acetone,
Examples include methyl ethyl ketone, diethyl ketone, diphenyl ketone, acetophenone, and the like. These compounds may be used alone or in combination of two or more.

GP using UV-254 nm detector of alkali-soluble phenolic resin used in the present invention
The polystyrene reduced weight average molecular weight (hereinafter, simply referred to as weight average molecular weight) according to the C pattern varies depending on the type of resin and the production method, but is usually 1,000 to 25,000, and preferably 2,500 to 12,000. If the average molecular weight is less than 1,000, the pattern shape, resolution and heat resistance tend to deteriorate. On the other hand, if it exceeds 25,000, the pattern shape, developability, and sensitivity deteriorate, which is not practical.

These alkali-soluble phenol resins can be used as those whose molecular weight and molecular weight distribution are controlled by known means. As a method for controlling the molecular weight or molecular weight distribution, the resin is crushed and solid-liquid extracted with an organic solvent having appropriate solubility, or the resin is dissolved in a good solvent and dropped into a poor solvent, or a poor solvent is used. Is added dropwise to perform solid-liquid or liquid-liquid extraction.

(B) Photosensitizer The photosensitizer used in the present invention is a quinonediazide sulfonic acid ester of a polyhydroxy compound.
Not all hydroxyl groups in the molecule need be esterified, but may be partially esterified. Specific examples of the esterified compound used as a photosensitizer include:
1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, and 1,2-benzoic acid ester of these polyhydroxy compounds
Naphthoquinonediazide-6-sulfonic acid ester, 2,
1-naphthoquinonediazide-4-sulfonic acid ester,
Examples thereof include 2,1-naphthoquinonediazide-5-sulfonic acid ester and 2,1-naphthoquinonediazide-6-sulfonic acid ester. The quinone diazide sulfonic acid ester of a polyhydroxy compound is obtained by converting a quinone diazide sulfonic acid compound into a quinone diazide sulfonic acid halide according to a conventional method, and then using sodium carbonate, sodium hydrogen carbonate, sodium hydroxide or hydroxide in a solvent such as acetone, dioxane or tetrahydrofuran. In the presence of an inorganic base such as potassium, or an organic base such as trimethylamine, triethylamine, tripropylamine, diisopropylamine, tributylamine, pyrrolidine, piperidine, piperazine, morpholine, pyridine, dicyclohexylamine, a quinonediazidesulfonic acid halide and a polyhydroxy compound, The quinonediazide sulfonic acid ester-based photosensitizer used in the present invention can be obtained by reacting

The hydroxy compound used here is a known one having a phenol group, and specific examples thereof include 2,3,4-trihydroxybenzophenone and
2,4,4'-trihydroxybenzophenone, 2,
3,4,4'-tetrahydroxybenzophenone, 2,
4,2 ', 4'-tetrahydroxybenzophenone,
Polyhydroxybenzophenones such as 2,3,4,2 ', 4'-pentahydroxybenzophenone; gallic esters such as methyl gallate, ethyl gallate and propyl gallate; 2,2-bis (4-hydroxyphenyl )
Polyhydroxybisphenylalkanes such as propane and 2,2-bis (2,4-dihydroxyphenyl) propane; tris (4-hydroxyphenyl) methane,
1,1-tris (4-hydroxy-3-methylphenyl) ethane, 1,1,1-tris (4-hydroxy-3
-Methylphenyl) ethane, 1,1,1-tris (4-
Hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) -1- (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-methylphenyl) -2-hydroxy-4-methoxy Polyhydroxytrisphenylalkanes such as phenylmethane;
1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-methyl-4-hydroxyphenyl) ethane, 1,1,3,3-
Polyhydroxytetrakisphenylalkanes such as tetrakis (4-hydroxyphenyl) propane; α, α,
α ', α'-tetrakis (4-hydroxyphenyl)-
3-xylene, α, α, α ′, α′-tetrakis (4-
(Hydroxyphenyl) -4-xylene, α, α, α ′,
Polyhydroxytetrakisphenyl xylenes such as α'-tetrakis (3-methyl-4-hydroxyphenyl) -3-xylene; 2,6-bis (2,4-dihydroxybenzyl) -p-cresol, 2,6-bis (2,4-
Dihydroxy-3-methylbenzyl) -p-cresol, 4,6-bis (4-hydroxybenzyl) resorcin, 4,6-bis (4-hydroxy-3-methylbenzyl) resorcin, 4,6-bis (4- A trimer of a phenol and a formalin such as hydroxybenzyl) -2-methylresorcin, 4,6-bis (4-hydroxy-3-methylbenzyl) -2-methylresorcin, and a phenolic compound represented by the following general formula (I) Examples thereof include tetramers of compounds and formalin, and novolac resins.

Embedded image (In the formula, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{3 to} R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms.)

In the photosensitizer used in the present invention, the ratio of esterification of quinonediazide sulfonic acid compound to these polyhydroxy compounds (average esterification rate)
Is not particularly limited, but the lower limit is usually 20%, preferably 30% as the mol% of the quinonediazide sulfonic acid compound relative to the hydroxyl group of the polyhydroxy compound, and the upper limit is usually 100%, preferably 95%. If the esterification ratio is too low, the pattern shape and the resolution may be deteriorated. If the esterification ratio is too high, the sensitivity may be lowered.

Among these, polyhydroxy trisphenylalkanes, polyhydroxytetrakisphenylalkanes, polyhydroxytetrakisphenylxylenes, polymers having a phenol nucleus of 3 or 4 such as trimers and tetramers of phenols and formalin. A system using a quinonediazide sulfonic acid ester of a hydroxy compound tends to obtain a high effect.

The photosensitizers used in the present invention may be used alone or in admixture of two or more. The compounding amount of the photosensitizer is usually 1 to 100 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the alkali-soluble phenol resin. If the amount is less than 1 part by weight, it becomes difficult to form a pattern. If the amount exceeds 100 parts by weight, the sensitivity is lowered and the development residue tends to occur.

(C) Polyhydroxybenzenes The polyhydroxybenzenes used in the present invention are those in which two or more hydroxyl groups are bonded to the benzene nucleus, and a lower alkyl group having 1 to 4 carbon atoms or a chlorine atom. A halogen atom such as a bromine atom may be bonded as a substituent. Specific examples of such polyhydroxybenzenes include catechol, resorcin, hydroquinone, pyrogallol, phloroglysin, 3-methylcatechol, 4-methylcatechol, 3-methoxycatechol, 2-methylresorcin, 5-methoxyresorcin,
4-ethylresorcin, methylhydroquinone, 2,3
-Dimethylhydroquinone, tetramethyl-p-benzoquinone, methoxyhydroquinone, 5-methylpyrogallol, methylgallate, ethylgallate, propylgallate, n-butylgallate, isobutylgalleate, trimethylhydroquinone, and the like, among which pyrogallol, 5-methyl Those having 3 hydroxyl groups such as pyrogallol (trihydroxybenzenes) are preferable.

Although the optimum amount of the polyhydroxybenzenes to be added may vary slightly depending on the raw material composition of the alkali-soluble phenol resin, the molecular weight and the molecular weight distribution, the addition amount of the alkali-soluble phenol resin and, if necessary, the addition amount thereof is not limited. In addition, it is usually 0.1 to 20 parts by weight, preferably 0.1% to 100 parts by weight in total with the following phenols.
It is 2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight.

(D) Phenols In the present invention, when a low molecular weight phenol other than polyhydroxybenzenes is further added as a sensitizer,
It is preferable because resist characteristics such as sensitivity are improved. Specific examples of such phenols include monophenols such as p-phenylphenol and p-isopropylphenol; biphenol, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxybenzophenone,
Bisphenol A (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol C (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol E (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol F (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol AP (manufactured by Honshu Chemical Industry Co., Ltd.), Bisphenol M (manufactured by Mitsui Petrochemical Industry Co., Ltd.), bisphenol P (manufactured by Mitsui Petrochemical Industry Co., Ltd.), bisphenol Z (manufactured by Honshu Chemical Industry Co., Ltd.), 1,1-bis (4-hydroxyphenyl) cyclopentane, 9,9- Bis (4-hydroxyphenyl) fluorene, 1,1-bis (5-methyl-2)
-Hydroxyphenyl) methane, 3,5-dimethyl-4
Bisphenols such as -hydroxybenzylphenol; 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1-tris (4-hydroxyphenyl)
Ethane, 1,1-bis (3-methyl-4-hydroxyphenyl) -1- (4-hydroxyphenyl) methane,
1,1-bis (2,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane,
1-bis (3,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane, 2,6
-Bis (5-methyl-2-hydroxybenzyl) -4-
Methylphenol, 2,6-bis (4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3-methyl-4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3,5 -Dimethyl-4-hydroxybenzyl) -4-methylphenol, trisphenol-PA (manufactured by Honshu Chemical Industry Co., Ltd.), trisphenol-TC
(Honshu Chemical Industry Co., Ltd.) and other trisphenols;
1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-methyl-4-
Hydroxyphenyl) ethane, 1,1,3,3- (4-
Hydroxyphenyl) propane, 1,1,5,5-tetrakis (4-hydroxyphenyl) pentane, α, α,
α ', α'-tetrakis (4-hydroxyphenyl)-
3-xylene, α, α, α ′, α′-tetrakis (4-
(Hydroxyphenyl) -4-xylene, α, α, α ′,
Tetrakisphenols such as α′-tetrakis (3-methyl-4-hydroxyphenyl) -3-xylene and α, α, α ′, α′-tetrakis (3-methyl-4-hydroxyphenyl) -4-xylene Is exemplified. Among the above, bisphenols, trisphenols, tetrakisphenols and the like are particularly preferable examples. The addition amount of these phenols varies depending on the composition of the alkali-soluble phenol resin, the molecular weight, the molecular weight distribution, and the type and amount of other additives, but the phenol amount is based on 100 parts by weight of the alkali-soluble phenol resin. The upper limit is usually 100 parts by weight or less, preferably 60 parts by weight or less, and the lower limit is usually 3 parts by weight or more.

The positive resist composition of the present invention is usually used by dissolving it in a solvent to apply it to a substrate to form a resist film. Specific examples of the solvent usable in the present invention include ketones such as acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone; alcohols such as n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and cyclohexanol; ethylene glycol dimethyl ether. , Ethers such as ethylene glycol diethyl ether, dioxane; alcohol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether; propyl formate, butyl formate, propyl acetate, butyl acetate,
Esters such as methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl lactate, ethyl lactate; cellosolve acetates such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glycol, Propylene glycols such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether; diethylene glycol monomethyl ether,
Diethylene glycols such as diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether; halogenated hydrocarbons such as trichloroethylene; toluene,
Aromatic hydrocarbons such as xylene; polar solvents such as dimethylacetamide, dimethylformamide, N-methylacetamide, etc. may be mentioned, and these may be used alone or in admixture of two or more.

The positive resist composition of the present invention may optionally contain a copolymer of styrene and acrylic acid, methacrylic acid or maleic anhydride in order to improve developability, storage stability and heat resistance. , A copolymer of an alkene and maleic anhydride, a vinyl alcohol polymer, a vinylpyrrolidone polymer, rosin, shellac and the like can be added. The amount of the polymer added is 0 to 100 parts by weight of the total alkali-soluble phenol resin.
It is 50 parts by weight, preferably 5 to 20 parts by weight.

The positive resist composition of the present invention may contain compatible additives such as a surfactant, a storage stabilizer, an anti-striation agent and a plasticizer, if necessary. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenol ether, and the like. Oxyethylene aryl ethers; polyethylene glycol dialkyl esters such as polyethylene glycol dilaurate and ethylene glycol distearate; Ftop EF3
01, EF303, EF352 (manufactured by Shin-Akita Kasei), Megafax F171, F172, F173, F177
(Dai Nippon Ink Co., Ltd.), Florade FC430, FC4
31 (Sumitomo 3M), Asahi Guard AG71
0, Surflon S-382, SC-101, SC-1
02, SC-103, SC-104, SC-105, S
Fluorinated surfactants such as C-106 (manufactured by Asahi Glass Co., Ltd.); organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); acrylic acid or methacrylic acid (co) polymer Polyflow No. 75, no. 95 (manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.). The amount of these surfactants is usually 2 parts by weight or less, preferably 1 part by weight or less, per 100 parts by weight of the solid content of the composition.

In the resist composition of the present invention, an alkaline aqueous solution is usually used as an alkaline developing solution, and specific examples thereof include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate and ammonia; ethylamine and propyl. Aqueous solutions of primary amines such as amines;
Aqueous solutions of secondary amines such as diethylamine and dipropylamine; aqueous solutions of tertiary amines such as trimethylamine and triethylamine; aqueous solutions of alcoholamines such as diethylethanolamine and triethanolamine; tetramethylammonium hydroxide, tetraethylammonium hydroxide; An aqueous solution of a quaternary ammonium hydroxide such as trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide, and trimethylhydroxyethylammonium hydroxide is exemplified. If necessary, a water-soluble organic solvent such as methanol, ethanol, propanol, and ethylene glycol, a surfactant, and a resin dissolution inhibitor may be added to the aqueous alkali solution.

A resist film can be formed by applying a resist solution prepared by dissolving the resist composition of the present invention in a solvent onto the surface of a substrate such as a silicon wafer by a conventional method and then removing the solvent by drying. As a coating method at this time, spin coating is particularly recommended. An exposure source used for exposure for forming a pattern on the resist film thus obtained includes an electron beam source such as an ultraviolet ray, a far ultraviolet ray, a KrF excimer laser beam, an X-ray, and an electron beam. Further, it is preferable to perform a heat treatment (post-exposure bake) after the exposure because the sensitivity can be improved and stabilized.

[0025]

As described above, according to the present invention, it is possible to obtain a resist composition in which an increase in viscosity during storage is suppressed and a change in film thickness is small, and a finer pattern can be obtained.

[0026]

The present invention will be more specifically described below with reference to synthesis examples and working examples. The parts and percentages in each example are based on weight unless otherwise specified. Further, the measured weight average molecular weight is the polystyrene-reduced weight average molecular weight in the pattern obtained by gel permeation chromatography using a UV 254 nm detector (hereinafter,
It is called Mw).

Reference Example 1 Synthesis of Novolac Resin a-1 In a 2 liter flask equipped with a cooling tube and a stirrer,
174 g of m-cresol, 217 g of p-cresol,
110 g of 2,3,5-trimethylphenol, 92.4 g of 92% formaldehyde, and oxalic acid dihydrate 1.
Put 70g, 90 ~ 1 using the mantle heater as a heat source
The reaction was carried out for 100 minutes while maintaining the temperature at 00 ° C. Then, the cooling tube was replaced with a distillation tube, and water was distilled off at 100 to 105 ° C for 30 minutes. Then, the temperature was further raised to 170 ° C, the pressure was reduced to 10 mmHg, and the temperature was further raised to 190 ° C. The reaction monomer and residual water were removed. After this,
The molten resin is returned to room temperature and novolac resin a-1 42
8 g was recovered. When the Mw of this novolak resin was measured, it was 4200.

Reference Example 2 Acquisition of Novolac Resin a-2 300 g of the novolak resin obtained in Synthesis Example 1 was mixed with 90 g of propylene glycol monomethyl ether acetate.
Then, 150 g of toluene was added and heated to 85 ° C. to dissolve with stirring. Attach the dropping funnel to the flask and adjust the temperature to 80 ~.
Toluene 255 was added from the dropping funnel while controlling at 85 ° C.
After dropping 0 g of the solution over 15 minutes, the temperature was kept for another 10 minutes. Then, the mixture was gradually cooled to room temperature and left still for 1 hour. The supernatant of the precipitated resin component was removed by decantation, 550 g of ethyl lactate was added, and the mixture was heated to 100 ° C. at 100 mmHg to remove residual toluene to obtain an ethyl lactate solution of novolak resin a-2. The Mw of this novolak resin was 6100.

(Reference Example 3) Synthesis of novolak resin a-3 144 g of m-cresol as a phenol compound, p-
Novolak resin a-3 ′ was obtained in the same manner as in Reference Example 1 except that 144 g of cresol and 241 g of 2,3,5-trimethylphenol were used and the amount of formaldehyde was changed to 80.1 g. Further, novolak resin a-3 was obtained by the same method as in Reference Example 2 except that 3000 g of xylene was used as a solvent for dissolving this resin a-3 '. The Mw of this resin was 4400.

Reference Example 4 Synthesis of Novolac Resin a-4 168 g of m-cresol as a phenol compound, p-
Cresol 168g, 3,5-dimethylphenol 16
Novolak resin a-4 was obtained in the same manner as in Reference Example 1, except that 3 g was used, the amount of formaldehyde was 102 g, and oxalic acid dihydrate was 1.5 g. The Mw of this novolak resin was 4,800.

Reference Example 5 Synthesis of Novolac Resin a-5 144 g of m-cresol as a phenol compound, 3,
5-dimethylphenol 190g, 2,5-dimethylphenol 163g, formaldehyde amount 80g
Novolak resin a-5 ′ was obtained in the same manner as in Reference Example 4 except that. Further, novolak resin a-5 was obtained in the same manner as in Reference Example 2 except that 180 g of propylene glycol monomethyl ether acetate and 3000 g of toluene were used as the solvent for dissolving this a-5 '.
The Mw of this resin was 6300.

Reference Example 6 Synthesis of Novolac Resin a-6 As a phenol compound, 96 g of m-cresol, 3,5
-Novolak resin a-6 'was obtained in the same manner as in Reference Example 4 except that 217 g of dimethylphenol and 217 g of 2,5-dimethylphenol were used and the amount of formaldehyde was changed to 80 g. Further, except that 150 g of propylene glycol monomethyl ether acetate and 2700 g of toluene were used as a solvent for dissolving the resin A-6 ′,
Novolak resin a-6 was obtained in the same manner as in Reference Example 5. The Mw of this novolak resin was 5,300.

Reference Example 7 Synthesis of Novolac Resin a-7 In a 2 liter flask equipped with a cooling pipe and a stirrer,
178 g of m-cresol, 222 g of p-cresol,
100 g of 3,5-dimethylphenol, 68.8 g of 92% formaldehyde, and 4.00 g of 35% hydrochloric acid were added, and the reaction was carried out for 100 minutes while maintaining the temperature at 90 to 100 ° C. with a mantle heater as a heat source. Then, the cooling pipe was replaced with a distillery, water was distilled off at 100 to 105 ° C. for 30 minutes, and then the temperature was raised to 190 ° C. to remove unreacted monomer and residual water. Then, the molten resin was returned to room temperature to recover the novolak resin A-7 '. Further, this novolak resin was fractionated by the same method as in Reference Example 5 to obtain novolac resin a-7. The Mw of this novolak resin was 6400.

The charged molar ratios of the resins of each reference example are summarized in Table 1.

[Table 1]

Description of abbreviations in Table 1: m / p = m-cresol combined with p-cresol m / p / T = m-cresol combined with p-cresol and 2,3,5-trimethylphenol m / p Combination of p / 3,5X = m-cresol, p-cresol and 3,5-dimethylphenol m / 3,5X / 2,5X = m-cresol, 3,5-dimethylphenol and 2,5-dimethylphenol Combined

Reference Example 8 Synthesis of Photosensitizer b-1 As a polyhydroxy compound, 2,6-bis (2,4-
Using dihydroxybenzyl) -p-cresol, 1,2-naphthoquinonediazide-5-sulfonic acid chloride in an amount corresponding to 70 mol% of this hydroxyl group was dissolved in dioxane to obtain a 10% solution. This solution at 20-25 ° C
While controlling the temperature to 3, triethylamine (1.2 equivalents of 1, -naphthoquinonediazide-5-sulfonic acid chloride) was added dropwise over 30 minutes, and the reaction was completed by holding it for another 2 hours. The precipitated salt was separated by filtration and poured into a 0.2% aqueous solution of oxalic acid 10 times the amount of the reaction solution. The precipitated solid is filtered, washed with ion-exchanged water, dried,
A quinonediazide sulfonic acid ester-based photosensitizer b-1 was obtained.

Reference Example 9 Synthesis of Photosensitizer b-2 A compound represented by the following formula (II) was used as a polyhydroxy compound, and 1,2-naphthoquinonediazide in an amount corresponding to 80 mol% of this hydroxyl group was used. -5-sulfonic acid chloride was dissolved in dioxane to give a 10% solution. Subsequent operations were carried out in the same manner as in Reference Example 8 using the photosensitizer b-2.
I got

Embedded image

(Reference Example 10) Synthesis of Photosensitizer b-3 2,3,4,4'-tetrahydroxybenzophenone was used as a polyhydroxy compound, and an amount of 1,2-corresponding to 75 mol% of this group was used. Naphthoquinone diazide-5
Dissolve sulfonic acid chloride in dioxane, 10%
Solution. Subsequent operations were performed in the same manner as in Reference Example 8 to obtain a photosensitizer b-3.

(Examples 1 to 10 and Comparative Examples 1 and 2) Resins having the compositions obtained in Reference Examples (for those obtained with ethyl lactate solution, the resin concentration in the solution was calculated from dry weight), photosensitizer,
Table 2 shows phenolic compounds and polyhydroxybenzenes.
Dissolved in ethyl lactate with the composition of 1.17 μm Teflon filter (polytetrafluoroethylene filter)
Then, a resist composition was prepared by filtration with, and was coated on a silicon wafer with a coater to measure the film thickness. Was. The above resist composition was heated and held at 35 ° C., and after 90 days, a film was formed in the same manner as the film thickness measurement immediately after preparation of the resist composition, and the film thickness was measured. The change in film thickness was as shown in Table 2.

[0040]

[Table 2]

As a result, it was found that addition of polyhydroxybenzenes to a resist composition containing a resin containing a phenol compound having two or more alkyl groups as a raw material can suppress the film thickness change.

Claims (3)

[Claims] 1. A positive resist composition containing an alkali-soluble phenol resin, a quinonediazide sulfonic acid ester-based photosensitizer, and polyhydroxybenzenes, wherein the alkali-soluble phenol resin is one or more phenols and one or more kinds. A positive resist composition, which is a novolak resin obtained by condensation with aldehydes or ketones, wherein at least one kind of phenol is a phenol compound having two or more alkyl groups. 2. The positive resist composition according to claim 1, wherein the phenol compound having two or more alkyl groups is dimethylphenol or trimethylphenol. 3. The positive resist composition according to claim 1, wherein the polyhydroxybenzenes are trihydroxybenzenes.