JPH09281702A - Positive resist composition - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a resist composition with little change in film thickness. In a positive resist composition containing an alkali-soluble phenol resin, a quinonediazidesulfonic acid ester-based photosensitizer, and a polyhydroxybenzene, a quinonediazidesulfonic acid ester-based photosensitizer is a polyhydroxy compound having a benzene nucleus of 3 or more. A positive resist composition comprising a quinonediazide sulfonate.

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 a photosensitive compound of a positive resist composition, trihydroxybenzophenones as described in JP-B-3-4896 and tetrahydroxy as described in JP-B-62-28457 have been used. Quinone diazide sulfonates of benzophenone compounds such as benzophenones are widely known. However, even if these photosensitive compounds are used, they do not always satisfy the required properties of the resist, and therefore quinonediazide sulfonic acid esters of trinuclear phenol compounds as described in JP-A-4-502519 and special compounds are not used. Kaihei 2-296248, the same 2
-269249, 2-269250, 2
-269251, 3-158856, 4-
502519, 6-167805, 7-1
A quinonediazide sulfonic acid ester of a polynuclear phenol compound having 3 or more benzene nuclei as described in JP-A Nos. 52152 and 7-159990 is proposed. However, when such a polynuclear quinonediazide sulfonic acid ester of a phenolic compound is used as a photosensitive compound (photosensitizer), the viscosity increases due to long-term storage, which greatly affects the film thickness, which is not suitable for forming a fine pattern. There was an obstacle.

[0004]

Under the above-mentioned conventional techniques, the inventors of the present invention have earnestly studied to obtain a resist composition having a small change in film thickness, and as a result, quinonediazide sulfonic acid ester of polynuclear phenol compound was used as a photosensitizer. It was found that the viscosity increase of the resist composition can be suppressed by adding polyhydroxybenzenes to the above resist composition, and the present invention has been completed.

[0005]

According to the present invention, there is thus provided a positive resist composition containing an alkali-soluble phenol resin, a quinonediazidesulfonic acid ester-based photosensitizer, and polyhydroxybenzenes, which is a quinonediazidesulfonic acid ester-based photosensitizer. Provided is a positive resist composition, wherein the agent is a quinonediazide sulfonic acid ester of a polyhydroxy compound having 3 or more benzene nuclei.

The present invention will be described in detail below. (A) Alkali-soluble phenol resin Specific examples of the alkali-soluble phenol resin include, for example, a condensation reaction product of a phenol compound and an aldehyde, a condensation reaction product of a phenol compound and a ketone,
A vinylphenol polymer, an isopropenylphenol polymer, a hydrogenation reaction product of these phenol resins, and the like can be mixed and used. Specific examples of the phenol compound used here include phenol and o-
Cresol, m-cresol, p-cresol, 2,3
-Dimethylphenol, 2,5-dimethylphenol,
3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 2-
t-butylphenol, 3-t-butylphenol, 4
-T-butylphenol, 2-methylresorcinol,
4-methylresorcinol, 5-methylresorcinol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropyl Examples include phenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, thymol and isothymol. These compounds may be used alone or in combination of two or more. Among these, cresols such as o-cresol, m-cresol and p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol and 3,5-
It is preferable to use in combination with a phenol having two or more alkyl groups such as dimethylphenol, 2,3,5-trimethylphenol, and 3,4,5-trimethylphenol. At this time, the ratio (molar ratio) of the cresols and the phenol compound having two or more alkyl groups
Is from 50:50 to 10:90, preferably from 40:60.
It can be arbitrarily set at about 20:80.

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. These condensation reaction products can be obtained by a conventional method, for example, by reacting the above-mentioned phenol compound with an aldehyde or a ketone in the presence of an acidic catalyst.

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 phenolic resins can be used by controlling the molecular weight and the molecular weight distribution 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 has a benzene nucleus of 3 or more, preferably 3 or more and 5 or less, more preferably 3 or 4 (hereinafter, simply referred to as polyhydroxy compound). There is) quinonediazide sulfonic acid ester. Specific examples of the esterified product used as a photosensitizer include 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, and 1,2-naphthoic acid ester of these polyhydroxy compounds. Quinonediazide-5-sulfonate, 1,2-naphthoquinonediazide-6-sulfonate, 2,1-naphthoquinonediazide-4-
Sulfonate, 2,1-naphthoquinonediazide-
Examples thereof include 5-sulfonic acid ester and 2,1-naphthoquinonediazide-6-sulfonic acid ester. The quinonediazide sulfonic acid ester of polyhydroxy compound is
After converting the quinonediazidesulfonic acid compound to a quinonediazidesulfonic acid halide according to a conventional method, acetone,
Sodium carbonate, sodium hydrogen carbonate, an inorganic base such as sodium hydroxide or potassium hydroxide, or trimethylamine in a solvent such as dioxane or tetrahydrofuran.
Used in the present invention by reacting a quinonediazide sulfonic acid halide with a polyhydroxy compound in the presence of an organic base such as triethylamine, tripropylamine, diisopropylamine, tributylamine, pyrrolidine, piperidine, piperazine, morpholine, pyridine and dicyclohexylamine. The quinonediazide sulfonic acid ester-based photosensitizer can be obtained.

The polyhydroxy compound used here is disclosed in JP-A-2-296248 and JP-A-2-26924.
No. 9 and No. 2-269250, No. 2-26925.
1 gazette, 3-158856 gazette, 4-502519.
No. 6,167,805, No. 7-152152, No. 7-159990 and the like, a quinonediazidesulfonic acid ester of a polynuclear phenol compound having 3 or more phenol nuclei, specifically, tris (4-
Hydroxyphenyl) methane, 1,1,1-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-methoxyphenylmethane, etc. Polyhydroxytrisphenylalkanes; 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,2,
Polyhydroxytetrakisphenylalkanes such as 2-tetrakis (3-methyl-4-hydroxyphenyl) ethane and 1,1,3,3-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 ′, α′-tetrakis (3-
Polyhydroxytetrakisphenyl xylenes such as 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-
A trimer of phenol and formalin such as bis (4-hydroxybenzyl) -2-methylresorcin, 4,6-bis (4-hydroxy-3-methylbenzyl) -2-methylresorcin, represented by the following general formula (I): The tetramer of the shown phenolic compound and formalin, the novolak resin whose phenol nucleus is 3-5, etc. are mentioned.

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.

The photosensitizers used in the present invention may be used alone or in combination 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 and 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 solvents 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; Ethers such as glycol dimethyl ether, ethylene glycol diethyl ether and dioxane; alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; propyl formate, butyl formate, propyl acetate, butyl acetate, methyl propionate, and ethyl propionate; Methyl butyrate,
Ester such as 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 glycol monomethyl ether acetate, propylene glycol monoethyl ether Propylene glycols such as acetate and propylene glycol monobutyl ether; diethylene glycols such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether and diethylene glycol diethyl ether; halogenated hydrocarbons such as trichloroethylene; aromatics such as toluene and xylene Hydrogen like; dimethylacetamide, dimethylformamide, such as a polar solvent such as N- methyl acetamide and the like, which may be used by either singly or in combination.

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. Specific examples thereof include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate, and ammonia; ethylamine, 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.

[0022]

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.

[0023]

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 A 2 liter flask equipped with a cooling tube and a stirrer was charged with m.
-Cresol 335 g, p-cresol 411 g, 36
% Formalin 394 g and oxalic acid dihydrate 2.45
g was added and the reaction was carried out for 35 minutes while maintaining the temperature at 95 to 100 ° C. After that, water is distilled off at 100 to 105 ° C. for 100 minutes, and the temperature is further raised to 170 ° C. and 10 mmH.
The pressure was reduced to g and the temperature was further raised to 190 ° C. to remove unreacted monomer and residual water. Then, the molten resin was returned to room temperature and 554 g of novolak resin a-1 was recovered. The Mw of this novolak resin was 5200.

Reference Example 2 Acquisition of Novolac Resin a-2 300 g of the novolak resin obtained in Reference Example 1 was mixed with 200 g of propylene glycol monomethyl ether acetate.
And 80 g of toluene were added, and the mixture was heated to 85 ° C. and dissolved with stirring. Attach the dropping funnel to the flask and adjust the temperature to 80-85 ° C.
2800 g of toluene is added from the dropping funnel in a state of being controlled to 1
After dropping for 5 minutes, the temperature was kept for 10 minutes. Then, the mixture was gradually cooled to room temperature and left still for 1 hour. After removing the supernatant liquid of the precipitated resin component by decantation, 550 g of ethyl lactate was added to 100 mm.
Residual toluene was removed by heating to 100 ° C. with Hg to obtain an ethyl lactate solution of novolak resin a-2. The Mw of this novolak resin was 7,100.

Reference Example 3 Synthesis of Novolac Resin a-3 A 2 liter flask equipped with a cooling tube and a stirrer was used.
-199 g of cresol, 139 g of p-cresol, 2,
160 g of 3,5-trimethylphenol, 92.4 g of 92% formaldehyde, and 1.70 of oxalic acid dihydrate.
90g-100g using a mantle heater as a heat source
The reaction was carried out for 100 minutes while maintaining the temperature at ℃. Then, the cooling tube was replaced with a distillation tube, water was distilled off at 100 to 105 ° C. for 30 minutes, and then the temperature was raised to remove unreacted monomer and residual water. Then, the molten resin was returned to room temperature and 428 g of novolak resin a-3 was recovered. Mw of this novolak resin was 3,900.

Reference Example 4 Synthesis of Novolak Resin a-4 The same method as in Synthesis Example 2 except that the resin a-4 obtained in Reference Example 3 was used as the novolac resin and the solvent for dissolving this was 3000 g of toluene. Due to the novolac resin a
An ethyl lactate solution of -4 was obtained. The Mw of the novolak resin a-4 was 5,300.

Reference Example 5 Synthesis of Novolac Resin a-5 In a 2 liter flask equipped with a cooling tube and a stirrer,
178 g of m-cresol, 222 g of p-cresol,
3,5-Dimethylphenol 100 g, 92% formaldehyde 68.8 g, salicylaldehyde 128.8
g 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. using the mantle heater as a heat source. Then, replace the cooling tube with a distillation tube, 10
After water was distilled off at 0 to 105 ° C. for 30 minutes, the temperature was continuously raised to remove unreacted monomer and residual water. After this,
The molten resin is returned to room temperature and novolak resin a-5 '4
30 g was recovered. A novolak resin a-5 was obtained in the same manner as in Synthesis Example 4, except that 2700 g of toluene was used as the solvent for dissolving this novolac resin. The Mw of the novolak resin a-5 was 6400.

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

[Table 1]

Description of the 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 Combined use of p / 3,5X = m-cresol, p-cresol and 3,5-dimethylphenol

Reference Example 6 Synthesis of Photosensitizer b-1 2,3,4,4'-tetrahydroxybenzophenone was used as the polyhydroxy compound, and the hydroxyl group of 75
1,2-naphthoquinonediazide in an amount corresponding to mol%
Dissolve 5-sulfonic acid chloride in dioxane and
It was a 0% solution. While controlling the temperature of this solution at 20 to 25 ° C, 1.2 equivalents of triethylamine of 1,2-naphthoquinonediazide-5-sulfonic acid chloride was added dropwise over 30 minutes, and the reaction was continued for 2 hours. Was completed. 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 content was filtered, washed with ion-exchanged water, and dried to obtain a quinonediazidesulfonic acid ester-based photosensitizer b-1.

Reference Example 8 Synthesis of Photosensitizer b-2 Tris (4-hydroxyphenyl) methane was used as a polyhydroxy compound, and 1,2-naphthoquinonediazide-5 in an amount corresponding to 85 mol% of this hydroxyl group was used. -Sulfonic acid chloride was dissolved in dioxane to give a 10% solution. Then, the same procedure as in Reference Example 7 was performed to remove the photosensitizer b
-2 was obtained.

Reference Example 9 Synthesis of Photosensitizer b-3 Trisphenol PA was used as a polyhydroxy compound.
(Made by Honshu Chemical Industry Co., Ltd.), 70 mol% of this hydroxyl group
1,2-naphthoquinonediazide-5-sulfonic acid chloride in an amount corresponding to was dissolved in dioxane to obtain a 10% solution. Then, a photosensitizer b-3 was obtained by the same operation as in Reference Example 7.

Reference Example 10 Synthesis of Photosensitizer b-4 As a polyhydroxy compound, 2,6-bis (2,4-) was used.
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. Then, a photosensitizer b-4 was obtained by the same operation as in Reference Example 7.

Reference Example 11 Synthesis of Photosensitizer b-5 As the polyhydroxy compound, the following formula (II) was used, and 1,2-naphthoquinonediazide-5-sulfonic acid in an amount corresponding to 80 mol% of this hydroxyl group was used. The chloride was dissolved in dioxane to give a 10% solution. Then, the same operation as in Reference Example 7 was carried out to obtain a photosensitizer b-5.

Embedded image

(Examples 1 to 11 and Comparative Examples 1 and 2) Resins obtained in the above-mentioned reference examples (for those obtained with the ethyl lactate solution, the resin concentration in the solution was calculated from the 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.

[0037]

[Table 2]

As a result, as a photosensitizing agent, 3
It was found that addition of polyhydroxybenzenes to the resist composition using the above quinonediazide sulfonic acid ester of polyhydroxy compound can suppress the film thickness change.

Claims (2)

[Claims] 1. A positive resist composition containing an alkali-soluble phenolic resin, a quinonediazidesulfonic acid ester-based photosensitizer, and polyhydroxybenzenes, wherein the quinonediazidesulfonic acid ester-based photosensitizer is a polyhydroxy compound having a benzene nucleus of 3 or more. The quinone diazide sulfonic acid ester of 1. 2. The positive resist composition according to claim 1, wherein the polyhydroxybenzenes are trihydroxybenzenes.