JPH05204149A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To provide the photoresist composition superior in sensitivity, film endurance rate, resolution, heat resistance, resist form, and developability. CONSTITUTION:This composition contains an alkali-soluble resin obtained by polycondensing phenols represented by formula I with the compounds represented by formula II in a molar ratio of 40:60-95:5, and 1,2-quinonediazido compounds represented by formula II. In formulae I and II, each of R1-R3 is, independently, optionally substituted alkyl, aryl, aralkyl, alkenyl, alkoxy, aryloxyl, arylcarbonyl, acyl, II, halogen, nitro, or OH; R4 is H or alkyl; and R5 is hydroxymethyl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-sensitive positive photoresist composition, and more particularly to a photoresist composition for microfabrication having a high resolution and sensitivity and a good pattern cross-sectional shape. It is a thing.

The positive type photoresist according to the present invention is applied to a substrate such as a semiconductor wafer, glass, ceramics or metal by spin coating method or roller coating method in 0.5.
It is applied to a thickness of ˜3 μm. Then, heat and dry,
A circuit pattern or the like is printed through an exposure mask by UV irradiation or the like, and developed to form a positive image.

Further, the pattern can be processed on the substrate by etching using the positive image as a mask. Typical fields of application include manufacturing processes for semiconductors such as ICs, manufacturing circuit boards such as liquid crystals and thermal heads, and other photofabrication processes.

[0004]

2. Description of the Related Art As a positive photoresist composition,
Generally, a composition containing an alkali-soluble resin and a naphthoquinonediazide compound as a photosensitive material is used. For example, as "novolac type phenol resin / naphthoquinone diazide substituted compound", USP-3,666,47
3, USP-4,115,128 and USP-4,
173,470 and the like, and as the most typical composition, "Novolak resin consisting of cresol-formaldehyde / trihydroxybenzophenone-1,2-naphthoquinone diazide sulfonate" is Thompson "Introduction to Micro". Lithography ”(LF Thompson“ Introdu
action to Microlitho-graph
y ”) (ACS Publishing, No. 219, P112-12)
It is described in 1).

The novolak resin as a binder can be dissolved in an alkaline aqueous solution without swelling, and when the generated image is used as an etching mask, it imparts a high resistance to plasma etching. Especially useful for applications.

Further, the naphthoquinonediazide compound used for the photosensitivity itself acts as a dissolution inhibitor which lowers the alkali solubility of the novolak resin, but when it is decomposed by irradiation with light, it produces an alkali-soluble substance, rather, it is a novolak resin. It is unique in that it acts to increase the alkali solubility, and is particularly useful as a photosensitive material for a positive photoresist because of its large property change with respect to light.

From this point of view, many positive photoresists containing a novolac resin and a naphthoquinonediazide type photosensitive material have been developed and put into practical use.
We have achieved sufficient results in line width processing up to about 2 μm.

However, the degree of integration of integrated circuits is increasing, and in the manufacture of semiconductor substrates such as VLSI,
It has become necessary to process an ultrafine pattern having a line width of 1 μm or less. In such applications,
In particular, there is a demand for a photoresist having high resolution, high pattern shape reproducibility that accurately copies the shape of an exposure mask, and high sensitivity from the viewpoint of high productivity.

In order to increase the degree of integration of the integrated circuit,
The etching method is shifting from the conventional wet etching method to the dry etching method, but since the temperature of the resist increases during dry etching, the resist must have high heat resistance to prevent thermal deformation. Has been done.

In order to improve the heat resistance of the resist, a resin containing no component having a weight average molecular weight of 2000 or less is used (JP-A-60-97347), and the total content from the monomer to the trimer is 10% by weight. %, A technique of using a resin of not more than 60% (Japanese Patent Laid-Open No. 60-189739) has been disclosed.

However, when a resin from which the above low molecular weight components have been removed or reduced is used, there is a problem that the sensitivity is usually lowered and the throughput in device manufacturing is lowered.

Attempts have also been made to improve the sensitivity and developability of the resist by adding a specific compound to the resist composition. For example, JP-A-61-141441 discloses a positive photoresist composition containing trihydroxybenzophenone. The positive photoresist containing trihydroxybenzophenone has improved sensitivity and developability, but the addition of trihydroxybenzophenone has a problem that heat resistance is deteriorated.

Further, JP-A 64-44439 and JP-A-1
-177032, 1-282748, 2-1035
No. 0, by adding an aromatic polyhydroxy compound other than trihydroxybenzophenone,
Although a device for increasing the sensitivity without deteriorating the heat resistance has been shown, improvement of the developing property is not always sufficient.

[0014]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a positive photoresist composition capable of obtaining a resist pattern having high sensitivity and excellent resolution, developability and heat resistance particularly in the production of semiconductor devices and the like. To provide things.

[0015]

Means for Solving the Problems The inventors of the present invention found that the above objects can be achieved by using a specific alkali-soluble resin and a quinonediazide compound, as a result of diligent study in consideration of the above characteristics. The present invention has been completed based on the findings.

That is, the object of the present invention is the following general formula (1):
And a compound represented by the general formula (2) in a molar ratio of phenols represented by the general formula (1) /
Compound represented by general formula (2) = 40/60 to 95/5
This has been achieved by a positive photoresist composition characterized by containing a 1,2-quinonediazide compound and an alkali-soluble resin obtained by polycondensation with aldehydes, which is used in a mol% ratio.

[0017]

[Chemical 3]

Here, R _{1 to} R ₃ may be the same or different and may be a substituted or unsubstituted alkyl group, aryl group,
It represents an aralkyl group, an alkenyl group, an alkoxy group, an alloxyl group, an arylcarbonyl group, an acyl group, and a hydrogen atom, a halogen atom, a nitro group and a hydroxyl group.

[0019]

[Chemical 4]

Here, R ₄ represents a hydrogen atom or an alkyl group, and R ₅ represents a hydroxymethyl group.

Examples of the compound represented by the general formula (1) include phenol, m-cresol, o-cresol and p.
-Cresol, o-isopropylphenol, m-isopropylphenol, p-isopropylphenol,
2,4-di-tert-hexylphenol, pt
ert-amylphenol, o-ethylphenol, m
-Ethylphenol, p-ethylphenol, p-te
rt-butylphenol, 2,5-xylenol, 3,
5-xylenol, 3,4-xylenol, 2,3-xylenol, 2,4-xylenol, 2,6-xylenol, 3-methyl-5-isopropylphenol, 2,
4-di-tert-amylphenol, 3-methyl-6
-Isopropylphenol, 2-methyl-6-isopropylphenol, p-methoxyphenol, m-methoxyphenol, 3,5-dimethoxyphenol, 2-methoxy-4-methylphenol, m-ethoxyphenol, p-ethoxyphenol, m -Propoxyphenol, p-propoxyphenol, m-butoxyphenol, p-butoxyphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2,
3,6-Trimethylphenol, o-benzylphenol, p-cumylphenol, 2-methyl-4-cumylphenol, 2-methoxy-6-cumylphenol, 4-
Methyl-2-cumylphenol, 5-methyl-2-cumylphenol, 2-ethyl-4-cumylphenol,
2,6-dicumylphenol, 2,4'-ethylidene bisphenol, 4,4'-ethylidene bisphenol,
2,2'-methylenebinu (4-methylphenol),
4,4 ′-(1-methylpropylidene) bisphenol, p-phenylphenol, m-xylylphenol, o-toluylphenol, p-cumenylphenol, m-isopropenylphenol, p-chlorophenol, p-nitro Phenol, 2,6-bishydroxymethyl-p-cresol, p-phenoxymethylphenol, p-benzoyloxyphenol, resorcinol and the like can be mentioned, and they can be used alone or in combination of two or more, but are not limited thereto. It is not something that will be done.

Examples of the compound represented by the general formula (2) include p-xylene glycol, bis (hydroxymethyl) dulene, bis (hydroxymethyl) dulene, and the like, which may be used alone or in admixture of two or more. It can be used, but is not limited to these.

The alkali-soluble resin of the present invention comprises a compound represented by the general formula (1) and a compound represented by the general formula (2) in a molar ratio of the compound represented by the general formula (1) / general formula. The compound represented by the formula (2) is used in a ratio of 40/60 to 95/5 (mol%) and obtained by polycondensation with aldehydes. If the molar ratio of the general formula (1) is less than 40 mol%, the sensitivity is lowered, and if it exceeds 95 mol%, the heat resistance is insufficient.

Aldehydes used in the above synthesis include, for example, formaldehyde, paraformaldehyde,
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, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, furfural, chloroacetaldehyde Also, acetals thereof, for example, chloroacetaldehyde diethyl acetal and the like can be used, and of these, formaldehyde is preferably used.

These aldehydes may be used alone or in combination of two or more. As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid or the like can be used.

The weight average molecular weight of the alkali-soluble resin thus obtained is preferably in the range of 2000 to 30000. If it is less than 2,000, the film loss of the unexposed area after development is large, and if it exceeds 30,000, the developing speed becomes low. Particularly preferred is the range of 6000 to 20000.

Here, the weight average molecular weight is defined by the polystyrene conversion value of gel permeation chromatography.

The 1,2-quinonediazide compounds used in the present invention include the following polyhydroxy compounds, 1,2-naphthoquinonediazide-5- (and / or -4).
-) An esterified product with sulfonyl chloride can be used.

Examples of polyhydroxy compounds include 2,
3,4-trihydroxybenzophenone, 2,4,4 '
-Trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2 ', 4 4'-
Tetrahydroxybenzophenone, 2,4,6,3 ',
4'-pentahydroxybenzophenone, 2,3,4
2 ', 4'-pentahydroxybenzophenone, 2,
3,4,2 ', 5'-pentahydroxybenzophenone, 2,4,6,3', 4 ', 5'-hexahydroxybenzophenone, 2,3,4,3', 4 ', 5'-hexahydroxy Polyhydroxybenzophenones such as benzophenone, polyhydroxyphenylalkylketones such as 2,3,4-trihydroxyacetophenone, 2,3,4-trihydroxyphenylpentylketone and 2,3,4-trihydroxyphenylhexylketone, Bis (2,4-dihydroxyphenyl) methane, bis (2,2
3,4-trihydroxyphenyl) methane, bis (2,2
4-dihydroxyphenyl) propane-1, bis (2,2
3,4-trihydroxyphenyl) propane-1, bis [(poly) hydroxyphenyl] alkanes such as nordihydroguaiaretylenic acid, propyl 3,4,5-trihydroxybenzoate, 2,3,4-tri Polyhydroxybenzoic acid esters such as phenyl hydroxybenzoate and phenyl 3,4,5-trihydroxybenzoate, bis (2,3,4-trihydroxybenzoyl) methane, bis (3-acetyl-4,5,6) -Trihydroxyphenyl) -methane, bis (2,3,4-trihydroxybenzoyl) benzene, bis (2,4,6-trihydroxybenzoyl) benzene and other bis (polyhydroxybenzoyl) alkanes or bis (polyhydroxybenzoyl) )
Aryls, ethylene glycol-di (3,5-dihydroxybenzoate), ethylene glycol-di (3,3
Alkylene-di (polyhydroxybenzoates) such as 4,5-trihydroxybenzoates), 2,3,4-
Biphenyltriol, 3,4,5-biphenyltriol, 3,5,3 ', 5'-biphenyltetrol,
2,4,2 ', 4'-biphenyl tetrol, 2,4
6,3 ', 5'-biphenylpentol, 2,4,6
2 ', 4', 6'-biphenylhexol, 2,3
Polyhydroxybiphenyls such as 4,2 ′, 3 ′, 4′-biphenylhexol, 4,4′-thiobis (1,3
-Bis (polyhydroxy) such as dihydroxy) benzene
Bis (polyhydroxyphenyl) ethers such as sulfides and 2,2 ′, 4,4′-tetrahydroxydiphenyl ethers, and bis (polyhydroxyphenyl) such as 2,2 ′, 4,4′-tetrahydroxydiphenyl sulfoxides ) Sulfoxides, bis (polyhydroxyphenyl) sulfones such as 2,2 ′, 4,4′-diphenylsulfone, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5'-tetramethyltriphenylmethane, 4,4 ', 2 ", 3", 4 "-pentahydroxy-3,5,3', 5'-tetramethyltriphenylmethane, 2,3,4 , 2 ', 3', 4'-hexahydroxy-5,5'-diacetyltriphenylmethane, 2,3,4,2 ', 3', 4 ', 3 ", 4"
-Octahydroxy-5,5'-diacetyltriphenylmethane, 2,4,6,2 ', 4', 6'-hexahydroxy-5,5'-dipropionyltriphenylmethane and other polyhydroxytriphenylmethanes , 3, 3,
3 ', 3'-tetramethyl-1,1'-spirobi-indane-5,6,5', 6'-tetrol, 3,3,3 '
3'-tetramethyl-1,1'-spirobi-indane-
5,6,7,5 ', 6', 7'-hexool, 3,
3,3 ', 3'-tetramethyl-1,1'-spirobi-
Indane-4,5,6,4 ', 5', 6'-hexool, 3,3,3 ', 3'-tetramethyl-1,1'-spirobi-indane-4,5,6,5', Polyhydroxyspirobi-indanes such as 6 ′, 7′-hexool,
3,3-bis (3,4-dihydroxyphenyl) phthalide, 3,3-bis (2,3,4-trihydroxyphenyl) phthalide, 3 ', 4', 5 ', 6'-tetrahydroxyspiro [phthalide -3,9'-xanthene] and other polyhydroxyphthalides, 2- (3,4-dihydroxyphenyl) -3,5,7-trihydroxybenzopyran, 2- (3,4,5-trihydroxyphenyl) ) −
3,5,7-trihydroxybenzopyran, 2- (3,3
4-dihydroxyphenyl) -3- (3,4,5-trihydroxybenzoyloxy) -5,7-dihydroxybenzopyran, 2- (3,4,5-trihydroxyphenyl) -3- (3,4 It is possible to use polyhydroxybenzopyrans such as 5-trihydroxybenzoyloxy) -5,7-dihydroxybenzopyran or flavono dyes such as morin, quercetin and rutin.

The naphthoquinonediazide ester photosensitive materials of these polyhydroxy compounds are used alone or in combination of two or more kinds.

The ratio of the photosensitive material to the alkali-soluble resin used is 5 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the resin. If this usage ratio is less than 5 parts by weight, the residual film ratio will be significantly reduced, while
If it exceeds the amount by weight, the sensitivity and the solubility in a solvent are lowered.

The composition of the present invention may further contain other polyhydroxy compounds in order to accelerate the dissolution in the developing solution. Preferred polyhydroxy compounds include:
Phenols, resorcin, phloroglucin, 2,3
4-trihydroxybenzophenone, 2,3,4,4 '
-Tetrahydroxybenzophenone, 2,3,4
3 ', 4', 5'-hexahydroxybenzophenone,
Acetone-pyrogallol condensation resin, phloroglide,
2,4,2 ', 4'-biphenyl tetrol, 4,4'
-Thiobis (1,3-dihydroxy) benzene, 2,
2 ', 4,4'-tetrahydroxydiphenyl ether, 2,2', 4,4'-tetrahydroxydiphenyl sulfoxide, 2,2 ', 4,4'-tetrahydroxydiphenyl sulfone and the like can be mentioned.

The amount of these polyhydroxy compounds is usually 5 per 100 parts by weight of the polyhydroxy compound of the present invention.
It can be added in an amount of 0 parts by weight or less, preferably 30 parts by weight or less.

As the solvent for dissolving the photosensitive material of the present invention and the alkali-soluble novolac resin, ketones such as methyl ethyl ketone and cyclohexanone, 4-ethoxy-2
-Ketoethers such as butanone, 4-methoxy-4-methyl-2-pentanone, alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ethers such as dioxane and ethylene glycol dimethyl ether, methyl cellosolve acetate, ethyl Cellosolve esters such as cellosolve acetate, fatty acid esters such as butyl acetate, methyl lactate and ethyl lactate, halogenated hydrocarbons such as 1,1,2-trichloroethylene, dimethylacetamide, N
Examples thereof include highly polar solvents such as methylpyrrolidone, dimethylformamide and dimethylsulfoxide.
These solvents may be used alone or as a mixture of a plurality of solvents.

The positive photoresist composition of the present invention may contain a surfactant in order to further improve the coating properties such as striation.

Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and other polyoxyethylene alkyl ethers, polyoxyethylene octylphenol ether, and polyoxyethylene. Polyoxyethylene alkyl allyl ethers such as atylenenonylphenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan Sorbitan fatty acid esters such as tristearate, polyoxyethylene sorbitan monolaurate, polyoxy Chile Nso sorbitan monopalmitate, polyoxyethylene sorbitan monostearate,
Nonionic surfactants such as polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate and other polyoxyethylene sorbitan fatty acid esters, Ftop EF301, EF303, EF
352 (manufactured by Shin-Akita Kasei Co., Ltd.), Megafac F17
1, F173 (Dainippon Ink Co., Ltd.), Florard F
C430, FC431 (Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC1
01, SC102, SC103, SC104, SC10
5, fluorine-containing surfactants such as SC106 (manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), acrylic acid-based or methacrylic acid-based (co) polymerization polyflow No. 75, no. 95 (manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.) and the like. The blending 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 alkali-soluble resin and the quinonediazide compound in the composition of the present invention.

These surfactants may be added alone or in some combinations.

The developer for the positive photoresist composition of the present invention includes sodium hydroxide, potassium hydroxide,
Inorganic alkalis such as sodium carbonate, sodium silicate, sodium metasilicate and aqueous ammonia, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, triethylamine and methyldiethylamine. Tertiary amines such as
Use aqueous solutions of alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, cyclic amines such as pyrrole and piperidine, and alkalis such as You can Further, an appropriate amount of alcohols and surfactants may be added to the above aqueous solution of alkalis for use.

If desired, the positive photoresist composition of the present invention may contain a dye, a plasticizer and an adhesion aid.

Specific examples thereof include dyes such as methyl violet, crystal violet and malachite green, plasticizers such as stearic acid, acetal resin, phenoxy resin and alkyd resin, and adhesion aids such as hexamethyldisilazane and chloromethylsilane. There is.

[0041]

The positive photoresist composition of the present invention can be used as a positive photoresist composition having high sensitivity, excellent resolution, developability and heat resistance. A good resist can be obtained by applying a suitable coating method such as a spinner or coater on a substrate (eg, silicon / silicon dioxide coating) as described above, exposing through a predetermined mask, and developing.

Examples of the present invention will be shown below, but the present invention is not limited thereto. Unless otherwise specified,% means% by weight. The weight average molecular weight was measured as follows. Toyo Soda Industrial TSKgel
GMH _XL , G ₄₀₀₀ H _XL , G ₃₀₀₀ H _XL , G ₂₀₀₀ H _XL
Gel permeation chromatography (GP) under the conditions of 40 ° C., a flow rate of 1 m1 / min, a THF solvent, and a detection wavelength of 282 nm using a Kamura connected to each of the above.
According to C), the weight average molecular weight with monodisperse polystyrene as a standard was calculated.

[0043]

[Examples and Comparative Examples]

(1) Synthesis of alkali-soluble resin a 35 g of m-cresol, 55 g of p-cresol, 18 g of bis (hydroxymethyl) dulene, 53 g of 37% aqueous formalin solution and 0.1 g of oxalic acid were charged in a three-necked flask and stirred at 100 The temperature was raised to ℃ and reacted for 15 hours. Then, raise the temperature to 200 ℃ and gradually increase to 5m.
The pressure was reduced to mHg, and water, unreacted monomers, formaldehyde, oxalic acid, etc. were distilled off. Then, the molten alkali-soluble resin was returned to room temperature and recovered.

The novolak resin a thus obtained had a weight average molecular weight of 6300 (in terms of polystyrene).

(2) Synthesis of alkali-soluble resin b m-cresol 15 g, p-cresol 40 g, 3,5
28 g of xylenol, 36 g of bis (hydroxymethyl) dulene, 53 g of 37% aqueous formalin solution and 0.1 g of oxalic acid were charged in a three-necked flask, and stirred for 10
The temperature was raised to 0 ° C. and the reaction was carried out for 15 hours. Then increase the temperature to 2
Raise it to 50 ° C, gradually reduce the pressure to 1 mmHg,
Water, unreacted monomers, formaldehyde, oxalic acid, dimer components, etc. were distilled off. Then, the molten alkali-soluble resin was returned to room temperature and recovered. The obtained alkali-soluble resin b had a weight average molecular weight of 4900 (converted to polystyrene).

(3) Synthesis of alkali-soluble resin c m-cresol 30 g, p-cresol 28 g, 2,6
-Bishydroxymethyl, p-cresol 31.2 g,
Bis (hydroxymethyl) isozulen 36.3 g, 37
% Formalin aqueous solution 38.2 g and oxalic acid 0.2 g were charged in a three-necked flask, heated to 110 ° C. with stirring, and reacted for 15 hours. Thereafter, the temperature was raised to 200 ° C. and the pressure was gradually reduced to 5 mmHg to distill off water, unreacted monomer, formaldehyde, oxalic acid and the like.
Then, the molten alkali-soluble resin was returned to room temperature and recovered.

The obtained alkali-soluble resin c had a weight average molecular weight of 4,700 (in terms of polystyrene).

(4) Synthesis of alkali-soluble resin d m-cresol 35 g, p-cresol 40 g, 2,
3,5-Trimethylphenol 12.6 g, bis (hydroxymethyl) dulene 27.2 g, 37% formalin aqueous solution 53 g and oxalic acid 0.1 g were charged into a three-necked flask and heated to 100 ° C. while stirring, The reaction was carried out for 15 hours. After that, raise the temperature to 220 ℃ and gradually increase to 5m.
The pressure was reduced to mHg, and water, unreacted monomers, formaldehyde, oxalic acid, etc. were distilled off. Then, the molten alkali-soluble resin was returned to room temperature and recovered. The obtained alkali-soluble resin d had a weight average molecular weight of 4,200 (in terms of polystyrene).

(5) Synthesis of novolac resin e 40 g of m-cresol, 60 g of p-cresol, 37%
54.0 g of formalin aqueous solution and 0.05 g of oxalic acid were charged into a three-necked flask, heated to 100 ° C. with stirring, and reacted for 7 hours. 30mm after cooling to room temperature
The pressure was reduced to Hg.

Then, the temperature was gradually raised to 150 ° C. to remove water and unreacted monomers. The obtained novolak resin had an average molecular weight of 7900 (in terms of polystyrene).

(6) Synthesis of novolac resin f 50% by weight of m-cresol and 50% by weight of p-cresol
And a cresol novolac resin (polystyrene-equivalent molecular weight 9400) synthesized in the same manner as in (1) above using an aqueous formalin solution, "Experimental Method of Polymer Synthesis" p. 32 (Masayoshi Kinoshita, Takayuki Otsu: Kagaku Dojin (1973)). The low molecular weight component was fractionated with reference to (1) to obtain a cresol novolak resin having a polystyrene equivalent molecular weight of 10060.

(7) Synthesis of Photosensitive Material A 2,3,4-trihydroxybenzophenone 11.5
g, 1,2-naphthoquinonediazide-5-sulfonyl chloride (30.2 g) and acetone (300 ml) were charged into a three-necked flask and uniformly dissolved. Then, a mixed solution of triethylamine / acetone = 11.4 g / 50 ml was gradually added dropwise and reacted at 25 ° C. for 3 hours. 1% of reaction mixture
It was poured into 1500 ml of an aqueous hydrochloric acid solution, the resulting precipitate was filtered off, washed with water and dried (40 ° C.), and 2,9.8 g of 2,3,4-trihydroxybenzophenone 1,2-naphthoquinonediazide-5-sulfonic acid ester was obtained. Got

(8) Synthesis of Photosensitive Material B 2,3,4,4′-tetrahydroxybenzophenone 1
2.3 g, 1,2-naphthoquinonediazide-5-sulfonyl chloride 40.3 g and 300 ml of acetone were charged into a three-necked flask and uniformly dissolved. Then, a mixed solution of triethylamine / acetone = 15.2 g / 50 ml was gradually added dropwise and reacted at 25 ° C. for 3 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, the precipitate formed was filtered off, washed with water and dried (40 ° C.), and then 2, 3, 4,
39.7 g of 1,2-naphthoquinonediazide-5-sulfonic acid ester of 4'-tetrahydroxybenzophenone
Got

(9) Preparation and Evaluation of Positive Photoresist Composition Cresol novolak resins a to f obtained in the above (1) to (6) and photosensitive material A obtained in the above (7) to (8) , B
Was dissolved in ethyl cellosolve acetate in the ratio shown in the following [Table 1] and filtered using a 0.2 μm microfilter to prepare a photoresist composition. The photoresist composition was applied to a silicon wafer using a spinner and dried on a vacuum adsorption hot plate at 90 ° C. for 90 seconds to obtain a resist film having a thickness of 1.2 μm.

[0055]

[Table 1]

Next, a reduction projection exposure apparatus FP manufactured by Canon Inc.
A-1550 was used to expose through a test chart mask, developed with a 2.38% tetramethylammonium hydroxide aqueous solution for 1 minute, washed with water for 30 seconds and dried.

The resist pattern of the silicon wafer thus obtained was observed with a scanning electron microscope to evaluate the resist. The results are shown in [Table 2] below.

The sensitivity was defined as the reciprocal of the exposure dose for reproducing a 0.70 μm mask pattern, and was shown as a relative value to the sensitivity of Comparative Example 1.

The residual film rate was expressed as a percentage of the ratio of the unexposed area before and after development.

The resolving power represents a limiting resolving power at an exposure amount for reproducing a 0.70 μm mask pattern.

The heat resistance is determined by baking a resist-patterned silicon wafer in a convection oven for 30 minutes.
It showed a temperature at which the transformation of the pattern did not occur.

The shape of the resist is represented by the angle (θ) formed by the resist wall surface and the plane of the silicon wafer in the 0.70 μm resist pattern cross section.

With respect to the developability, when the peeling of the surface layer and the film residue were not observed, the result was good, and when it was observed slightly, the result was Δ.
Expressed as

[0064]

[Table 2]

That is, the resist composition of the present invention has a sensitivity,
It can be seen that the residual film rate, resolution, heat resistance, resist shape and developability are excellent.

Claims (1)

[Claims] 1. A phenol represented by the general formula (1) and a compound represented by the general formula (2) in a molar ratio of phenol represented by the general formula (1) / general formula (2). Used at a ratio of the compound represented by: 40/60 to 95/5 mol%,
A positive photoresist composition comprising an alkali-soluble resin obtained by polycondensation with aldehydes and a 1,2-quinonediazide compound. [Chemical 1] Here, R _{1 to} R ₃ may be the same or different and may be a substituted or unsubstituted alkyl group, aryl group, aralkyl group, alkenyl group, alkoxy group, alloxyl group, arylcarbonyl group, acyl group, and hydrogen atom, Represents a halogen atom, a nitro group, and a hydroxyl group. [Chemical 2] Here, R ₄ represents a hydrogen atom or an alkyl group, and R ₅ represents a hydroxymethyl group.