JPH02247653A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To improve the coating performance of a compsn. and the preservation stability of a soln. by using a specified keto-ether solvent. CONSTITUTION:This compsn. is composed of an alkali-soluble resin (A), 1,2- naphthoquinonediazido-4(and/or -5)-sulfonic ester (B) and a keto-ether solvent (C) having 130-170 deg.C b.p. represented by the formula [where R1 is 1-4C alkylene and R2 is 1-3C (branched) alkyl]. 4-Methoxy-4-methyl-2-pentanone may be used as the component C and the component C may be mixed with other solvent. Novolak resin may be used as the component A and the ester of 1,2- naphthoquinone-diazido-4(and/or -5)-sulfonic acid with a polyhydroxy arom. compd. as the component B.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a positive photoresist sensitive to radiation, and more specifically, it is used in the manufacturing process of semiconductors such as ICs, liquid crystals, thermal heads, etc. The present invention relates to a photoresist composition for microfabrication that has excellent coating performance and solution stability and is suitably used in the production of circuit boards and other photo application processes.

"Prior Art" As a positive photoresist composition, a resist composition is generally used in which an alkali-soluble resin and a naphthoquinone diazide compound as a photosensitive material are dissolved in a cS solvent. For example, r novolak type phenolic resin/
USP 386 as “Naphthoquinonediazide Substituted Compounds”
No. 6473, No. 4115128, No. 4173470, etc., and an example of the most typical composition "Novolac resin consisting of cresol-formaldehyde/trihydroxybenzophenone-1,1-naphthoquinonediazide sulfonic acid ester" is given in Thompson's "Introduction".・Tou Microlithography J (L, F,
Thompson rlntro-ductphone
to Microljtho-graphyJ AS
C Publishing, No. 219, P112-121).

Novolac resins as binders are particularly useful in this application because they can be dissolved in aqueous alkaline solutions without swelling and also provide high resistance to plasma etching, especially when the resulting image is used as an etching mask. It is. In addition, the naphthoquinone diazide compound used in photosensitive materials itself acts as a dissolution inhibitor that reduces the alkali solubility of the novolac resin, but when it decomposes upon exposure to light, it produces alkali-soluble substances and rather reduces the alkali solubility of the novolak resin. It is unique in that it acts as a light enhancer, and because of its large change in properties with respect to light, it is particularly useful as a photosensitive material for positive photoresists.

From this point of view, many positive photoresist compositions containing novolac resins and naphthoquinonediazide-based photosensitive materials have been developed and put into practical use, and these compositions have been particularly frequently used in recent years, when a high degree of integration of integrated circuits is required. .

However, when a photoresist composition made by dissolving an alkali-soluble resin and a naphthoquinone cyacyto-based photosensitive material in a solvent is coated on a substrate, coating unevenness called striation occurs, reducing the linearity and reproducibility of the pattern. death,
A problem often arises in that it is not possible to form a resist pattern with the required precision.

Furthermore, recently, substrates such as silicon wafers have tended to have larger diameters, which causes the problem that uncoated areas occur when a resist composition is applied onto the substrate.

In order to improve this coating property, Japanese Patent Application Laid-Open No. 58-10514
No. 3, No. 5B-203434, and No. 62-36657 contain known solvents for resist compositions such as ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, It is described that a fluorine-containing surfactant is added to N,N-dimethylformamide, dioxane, cyclohexanone, cyclopentanone, γ-butyl lactone, ethyl lactate, and methyl lactate.
P 4526856 and Japanese Patent Application Laid-open No. 59-231534 disclose that cyclopentanone, cyclohexane and carbon
The combination of 115 to 12 aliphatic alcohols is described.

In addition, in Japanese Patent Application Laid-open No. 60-24545, 60 to 170℃
(7) It has been disclosed that striations can be improved by combining a solvent with a boiling point with a solvent with a boiling point of 180 to 350°C.

Further, US Pat. No. 3,666,473 discloses combining butyl acetate and xylene with ethylene glycol monomethyl ether acetate. Apart from the above-mentioned problems, photoresist compositions containing a 1,2-naphthoquinonediazide-based photosensitizer, for example, with a pore size of 0. 2μ
If left after filtration with a filter, fine particles that cannot be observed with the naked eye (naphthoquinone diazide photosensitizer)
If the resist composition containing these fine particles is stored for a longer period of time, precipitation may eventually occur.

When a resist pattern is formed on a wafer using a resist composition containing such fine particles, there is a problem that the fine particles remain in areas where the resist should be removed by development, resulting in a decrease in resolution.

In order to improve this stability over time, JP-A-61-260
No. 239 lists substances with high boiling points such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl malonate, ethyl cyanoacetate, and butanediol.
20° C.) and a solubility parameter of 11 to 12.

Also, JP-A-62-123444, JP-A No. 63-2201
In No. 39, for example, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, methyl 2-hydroxypropisinate,
Ethyl 2-hydroxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, 2
-propyl hydroxypropionate, ethyl 2-methoxypropionate, bucopyl 2-ethoxyb a pionate,
JP-A-59-155838 discloses that stability can be improved by using a solvent containing monooxymonocarboxylic acid esters such as methyl 2-ethoxypropionate and ethyl 2-ethoxypropionate. Cyclopentanone is disclosed to be particularly effective.

Furthermore, JP-A-60-121445 and JP-A No. 62-2843
No. 54, No. 62-178562, No. 63-24244
No. 63-113451 discloses a 1,2-quinonediazide compound with improved storage stability.

``Problems to be Solved by the Invention'' As described above, the coating performance and storage stability of the solution are affected not only by the attributes of the constituent components such as the photosensitizer and binder polymer, but also by the solvent. It is known to be a characteristic. However, the reality is that almost no solvent is known that can simultaneously improve the two problems of coating performance and solution storage stability.

The first object of the present invention is to provide a positive photoresist composition that is free from failures such as unpainted areas and striations and has excellent coating performance.

Another object of the present invention is to provide a positive-working photoresist composition that has excellent storage stability as a solution and does not cause precipitation of photosensitizer particles during storage.

The inventors of the present invention have taken note of the above-mentioned characteristics and have conducted intensive studies, and have found that a photoresist composition using a solvent having a ketoether structure in its molecule has unique coating performance. The present inventors have discovered that the present invention is excellent in terms of storage stability regarding the precipitation of photosensitive agent fine particles, and have completed the present invention.

That is, the object of the present invention is to (a) an alkali-soluble resin;
(b) 1,2-naphthoquinonediazide-4(or/and-5)-sulfonic acid ester, and (c) general formula (I
) A positive photoresist composition characterized by comprising a ketoether solvent having a boiling point of 130 to 170° C. General formula (I) % Formula % R1: Alkylene group having 1 to 4 carbon atoms R2: This was achieved by a straight chain or branched alkyl group having 1 to 3 carbon atoms. Note that the alkylene group means a divalent aliphatic linking group.

The present invention will be explained in detail below.

As the solvent represented by the general formula (I) and having a boiling point in the range of 30 to 170°C, for example, 4-n-propoxy-2
-propanone, 4-iso-propoxy-2-propanone, 4-methoxy-2-butanone, 4-ethoxy-2-
Butanone, 4-n-propoxy-2-butanone, 4-i
so-propoxy-2-butanone, 5-methoxy-2-
Pentanone, δ-ethoxy-2-pentanone, 5-methoxy-4-methyl-2-pentanone, 5-methoxy-3
-Methyl-2-pentanone, 5-methoxy-4-methyl-2-pentanone, 4-methoxy-4-methyl-2-pentanone, 4-ethoxy-4-methyl-2-pentanone, 4-ethoxy-4-methyl -2-butanone, 4-ethoxy-3-methyl-2-butanone, and the like. Among these, 4-methoxy-4-methyl-2-bentanone is particularly preferred.

The preferred boiling point range is 130-170°C.

Since photoresist coating solvents are required to be safe against fire and explosion, a solvent with as high a flash point as possible is desired. However, a solvent with a high flash point requires high temperature and a long time to completely evaporate in the baking process that is performed after the photoresist coating process.

The 1,2-naphthoquinonediazide thread-ring photoresist used in positive photoresists has a relatively low decomposition temperature (I20
℃), so the baking temperature cannot be raised higher than 110℃. Therefore, in practical terms, there is a limit to the use of solvents with very high boiling points.

If baking is insufficient and a resist with a large amount of residual solvent is used as it is, resist properties, especially residual film rate and adhesion, will deteriorate, which is undesirable.

Conversely, the use of highly volatile solvents presents severe coating problems. That is, when a solvent with a low boiling point is used in a method of spin coating a wafer, the drying time becomes shorter than the resist spreading time, making it difficult to uniformly coat the entire wafer.

In the present invention, it is preferable to mainly use the ketonydel solvent represented by the general formula (I), but other solvents may be used in an amount of 70% by weight, preferably 50% by weight, more preferably 50% by weight of the total amount of solvent. It can be mixed within the range of 30% by weight of ungrooved.

Specific examples of other solvents that can be mixed include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol isopropyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol. dimethyl ether,
Ethers such as propylene glycol monomethyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, benzyl ethyl ether, dihexyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, butyl acetate, amyl acetate, hexyl acetate, Esters such as butyl propionate, amyl propionate, propyl butyrate, butyl butyrate, ethyl benzoate, diethyl oxalate, diethyl maleate, ethylene carbonate, propylene carbonate, γ-butyrolactone, γ-valerolactone, methyl ethyl ketone, di-1so-butyl ketone , methyl-1s
o-butyl ketone, methyl-n-butyl ketone, di-1
so-propylketone, methyl-n-amylketone, methyl-1so-amylketone, 3-methyl-2-hexanone, 4-methyl-2-hexanone, methyl-n-hexylketone, methyl-1so-hexylketone, 4-methyl -2-heptanone, 5-methyl-2-heptanone,
Aliphatic ketone necks such as 3-heptanone, 4-heptanone, 2,6-dimethyl-4-heptanone, cyclobutanone,
Alicyclic ketone necks such as cyclopentanone and cyclohexanone, diketones such as acetylacetone and acetonylacetone, 1-methoxy-2-butanone, 1-ethoxy-2
-butanone, other ketoales such as 1-methoxy-3-pentanone, 1-ethoxy-3-pentanone, 1-methoxy-2-pentanone, 1-ethoxy-2-pentanone, 4-hydroxy-2-butanone, 3 -Hydroxy-2
-butanone, 3-hydroxy-2-pentanone, 5-hydroxy-2-pentanone, 3-hydroxy-2-hexanone, 4-hydroxy-3-methyl-2-butanone,
Ketols such as 3-hydroxy-3-methyl-2-butanone and 4-hydroxy-4-methyl-2-pentanone;
Alcohol necks such as butyl alcohol, n-amyl alcohol, 1so-amyl alcohol, benzyl alcohol, cyclohexanol, furfuryl alcohol, methyl 2-methoxyacetate, ethyl 2-ethoxyacetate, methyl 2-hydroxypropionate, 2-hydroxypropion Ethyl acid, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, propyl 2-hydroxypropionate, ethyl 2-methoxypropionate, propyl 2-ethoxypropionate, methyl 2-ethoxypropionate, 2-ethoxypropionate Examples include monooxycarboxylic acid esters such as ethyl, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and anisole, and highly polar solvents such as dimethylacetamide, N-methylpyrrolidone, dimethylformamide, and dimethylsulfoxide.

Examples of the alkali-soluble resin used in the present invention include novolac resin, acetone-pyrogallol resin, polyhydroxystyrene, and derivatives thereof.

Among these, novolac resins are particularly preferred, and are obtained by addition-condensing a predetermined monomer as a main component with an aldehyde in the presence of an acidic catalyst.

The predetermined monomers include phenol, cresols such as m-resol, p-cresol, and 0-cresol;
2,5-xylenol, 3,5-xylenol, 3,4
- xylenol, xylenol such as 2.3-xylenol, m-ethylphenol, p-ethylphenol,
Alkylphenols such as 0-ethylphenol and pt-butylphenol, p-methoxyphenol, m-
Methoxyphenol, 3,5-dimethoxyphenol,
Alkoxyphenols such as 2-methoxy-4-methylphenol, m-ethoxyphenol, p-ethoxyphenol, m-propoxyphenol, p-propoxyphenol, m-butoxyphenol, p-butoxyphenol, 2-methyl-4 -Bisalkylphenols such as isopropylphenol, m-chlorophenol,
Hydroxy aromatic compounds such as p-chlorophenol, 0-chlorophenol, dihydroxybiphenyl, bisphenol A1 phenylphenol, resorcinol, and naphthol can be used alone or in combination of two or more, but are not limited to these. do not have.

Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde 1, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, 〇-hydroxybenzaldehyde, m
-Hydroxybenzaldehyde, p-hydroxybenzaldehyde, 0-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, 〇-nitrobenzaldehyde, m-nitrobenzaldehyde,
p-Nitrobenzaldehyde, 0-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, p-n-butylbenzaldehyde, furfural, chloroacetaldehyde and their acetals, such as oO acetaldehyde, diethyl acetal, etc. Among 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, etc. can be used.

The weight average molecular weight of the novolac resin thus obtained is:
The range is preferably from 2,000 to 30,000. 2
If it is less than 000, the film loss after development in the unexposed area will be large;
If it exceeds 0000, the development speed will become low. Particularly preferred is a range of 6,000 to 20,000.

Here, the weight average molecular weight is defined by the polystyrene equivalent value determined by gel permeation chromatography.

As the 1,2-naphthoquinonediazide compound used in the present invention, an ester of 1,2-naphthoquinonediazide-5-sulfonic acid or 1,2-naphthoquinonediazide-4-sulfonic acid and a polyhydroxy aromatic compound is used. .

The polyhydroxy aromatic compound contains 3 in one molecule.
Those having 2 or more hydroxyl groups are preferred, for example, 2.
3. 4-1 lyhydroxybenzophenone, 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
Polyhydroxy benzophenones such as '-hexahydroxybenzophenone, polyhydroxy such as 2゜3.4-trihydroxyacetophenone, 2,3゜4-trihydroxyphenylpentyl ketone, 2゜3.4-)dihydroxyphenylhexyl ketone, etc. Phenyl alkyl ketones, bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)propane-1, bis(2,3,4) -)dihydroxyphenyl)propane-
1. Bis((poly)) such as nordihydroguaiaretic acid
hydroxyphenyl)alkanes, 3. 4. Propyl 5-trihydroxybenzoate, 2. 3. Phenyl 4-trihydroxybenzoate, 3. 4. 5-) Polyhydroxybenzoic acid esters such as phenyl dihydroxybenzoate, bis(2,3,4-trihydroxybenzoyl)methane, bis(3-acetyl-4,5,6-trihydroxyphenyl)-methane, Bis(2゜3.4-trihydroxybenzoyl)benzene, bis(2,4,6
- Bis(polyhydroxybenzoyl)alkanes or bis(polyhydroxybenzoyl)aryls such as trihydroxybenzoyl)benzene, ethylene glycoludi(3,5-dihydroxybenzoate), ethylene glycoludi(3,4,5-trihydroxybenzoate) ) and other alkylene di(polyhydroxybenzoates)
0.2. 3. 4-biphenyltriol, 3, 4
．． 5-biphenyltriol, 3. 5. 35'-
Biphenyltetrol, 2. 4. 2'4'-biphenyltetrol, 2. 4. 6. 3'5'-biphenylpentol, 2. 4. 6. 2'4', 6'-
biphenylhexol, 2. 3. 4゜2', 3',
Polyhydroxybiphenyls such as 4'-biphenylhexol, 4,4'-thiobis(I,3-dihydroxy)
Bis(polyhydroxy) sulfides such as benzene, 2
．． 2', 4. Bis(polyhydroxyphenyl) ethers such as 4-tetrahydroxydiphenyl ether, bis(polyhydroxyphenyl)sulfoxides such as 2°2'4.4'-tetrahydroxydiphenyl sulfoxide, 2. 2', 4. Bis(polyhydroxyphenyl)sulfones such as 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. , 23',4'-hexahydroxy-5,5'-diacetyltriphenylmethane, 2.
3. 4. 23',4',3",4"-octahydroxy-5,5'-diacetyltriphenylmethane, 2°4.6.2',4',6'-hexahydroxy-5,5
Polyhydroxytriphenylmethanes such as '-dibrobionyltriphenylmethane, 3,3°3',3'-tetramethyl-1,1'-spirobiindane-5,6,5
', 6'-tetrol, 3, 3. 3', 3
'-Tetramethyl-1,1'-spirobiindane-5
, 6,7,5', 6'7'-hexiol, 3.
3. 3', 3'-tetramethyl-1,11-spirobiindane-4゜5.6.4', 5', 6'-hexiol, 3゜3.3', 3'-tetramethyl-1, 1
'-Spirob Indan-4, 5, 6, 5', 6'
, polyhydroxyspirobiindans such as 7'-hexiol, 3,3-bis(3,4-dihydroxyphenyl)phthalide, 3,3-bis(2,3,4-trihydroxyphenyl)phthalide, 3'45',6'-
Polyhydroxyphthalides such as tetrahydroxyspiro[phthalide-3,9'-xanthenco, etc., or flavonoid pigments such as morin, quercetin, and rutin can be used.

Furthermore, low-nuclear substances of phenolic resins such as novolac resins can also be used.

These polyhydroxy compounds may be used alone or in combination of two or more.

A conventional method is used for the esterification reaction between the polyhydroxy compound and 1,2-naphthoquinonediazide-5-sulfonyl chloride or 1,2-naphthoquinonediazide-4-sulfonyl chloride. That is, a predetermined amount of a polyhydroxy compound, 1,2-naphthoquinonediazide-5-sulfonyl chloride or 1,2-naphthoquinonediazide-4-sulfonyl chloride, and a solvent such as dioxane, acetone, methyl thiethyl ketone, N-methylpyrrolidone, etc. The mixture is charged into a flask, and a basic catalyst such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, triethylamine, etc. is added dropwise to cause condensation. The obtained product is purified and dried after washing with water. A photosensitive material of 1,2-naphthoquinonediazide can be prepared by the above method.

The esterification rate (defined as an average value) can be controlled by the mixing ratio of the raw material polyhydroxy compound and 1,2-naphthoquinonediazide-5 (and/or -4)-sulfonyl chloride.

Namely 1. Added 1,2-naphthoquinonediazide-5
Since substantially all of the (and/or -4)-sulfonyl chlorides undergo an esterification reaction, the molar ratio of the raw materials may be adjusted in order to obtain a mixture with a desired esterification rate.

If necessary, 1,2-naphthoquinonediazide-5-sulfonic acid ester and 1,2-naphthoquinonediazide-4
- A sulfonic acid ester can also be used in combination.

In addition, the reaction temperature in the above method is usually -20 to 60
℃, preferably 0 to 40℃.

The photosensitive materials used in the present invention synthesized as described above are incorporated into the alkali-soluble resin alone or in combination of two or more in the resist composition.

The blending amount is 5 to 100 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the alkali-soluble resin. If the usage ratio is less than 5 parts by weight, the residual film rate will drop significantly, and if it exceeds 100 parts by weight, sensitivity and solubility in solvents will drop.

The composition of the present invention may further contain a polyhydroxy compound to promote dissolution in a developer. Preferred polyhydroxy compounds include phenols,
resorcin, phloroglucin, 2. 3. 4-trihydroxybenzophenone, 2, 3. 4. 4'-tetrahydroxybenzophenone, 2. 3. 4. 3
Examples include ', 4', 5'-hexahydroxybenzophenone, acetone-pyrogallol condensation resin, and phloroglucide.

The amount of the polyhydroxy compound blended is usually 100 parts by weight or less, preferably 5 to 50 parts by weight, per 100 parts by weight of the quinonediazide compound.

A surfactant can be added to the positive photoresist composition of the present invention in order to further improve coating properties such as striations.

Examples of surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,
Polyoxyethylene alkyl ethers such as polyoxyethylene cetyl ether and polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene/polyoxybrobylene block Cobolimers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate,
Nonions such as polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, etc. Series surfactant, FTOP EF301°EF303. EF352 (manufactured by Shin Akita Kasei ■), Megafac F171. F173 (manufactured by Dainippon Ink), Florado FC430, FC431 (
Manufactured by Sumitomo 3M) 1, Asahi Guard AC; 710,
Surflon S-382, 5CIOI, 5C102°5C
Fluorine-based surfactants such as 103, 5C104, 5C105, 5CIO6 (manufactured by Asahi Glass ■), organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical ■), acrylic acid-based or methacrylic acid-based (co)polymerized Polyflow No.
75. No. 95 (manufactured by Kyoeisha Yushi Kagaku Kogyo ■)
etc. can be mentioned. The blending amount of these surfactants is usually 2M parts or less, preferably 1 part by weight or less, per 100 parts by weight of the alkali-soluble resin and quinonediazide compound in the composition of the present invention.

These surfactants may be added alone, or
It can also be added in several combinations.

Examples of the developer for the positive photoresist composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, etc. primary amines, diethylamine, di-n-
Tertiary amines such as butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, and quaternary ammonium salts such as tetramethylammonium hydroxide and tetramethylammonium hydroxide. , virol, cyclic amines such as piperidine, etc., and aqueous solutions of alkalis such as virol and piperidine can be used. Furthermore, an appropriate amount of an alcoholic acid and a surfactant may be added to the aqueous solution of the alkali.

The positive photoresist composition of the present invention may contain a dye, a plasticizer, and an adhesion aid, if necessary.

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

The above positive photoresist composition is applied onto a substrate (e.g. silicon/silicon dioxide coated) used in the manufacture of precision integrated circuit elements using an appropriate coating method such as a spinner coater, and then passed through a prescribed mask. A good resist can be obtained by exposing and developing.

"Effect of the invention" According to the invention, an alkali-soluble resin and l.

Dissolving the 2-naphthoquinone diazide compound in a specific solvent has the following effects.

(I) It has good coating properties, and when forming a coating film by spin coating, there is almost no occurrence of striations, and a resist film having an extremely smooth surface is formed.

(2) Resist! The composition has good wettability with respect to the substrate, and a uniform and complete resist film can be formed without leaving any residue.

(3) It has excellent stability over time and does not cause precipitation or precipitation of fine particles even after long-term storage, so resist performance is not affected.

"Example" The present invention will be described below with reference to Examples, but the present invention is not limited thereto. Moreover, unless otherwise specified, % indicates weight %.

Example 1 Novolak resin (m-cresol) obtained by condensing m-cresol and p-cresol with formaldehyde using oxalic acid as a catalyst.
-cresol/p-cresol = 40/60 molar ratio, M
w=7200) 100 parts by weight and 2. 3. 4. 4'
- 26 parts by weight of 1,2-naphthoquinonediazide-5-sulfonic acid ester of tetrahydroxybenzophenone (average esterification rate 75%), fluorosurfactant rFC-
430J (Fluorochemical - manufactured by Sumitomo 3M) 0.0
Dissolve 15 parts by weight in 320 parts by weight of 4-methoxy-4-methyl-2-pentanone (boiling point 156°C),
A fetresist composition was prepared by filtration using a microfilter.

This photoresist composition was coated onto a silicon wafer using a spinner and heated in a convection oven under a nitrogen atmosphere for 9 days.
The resist film was dried at 0° C. for 30 minutes to obtain a resist film having a thickness of 1° to 20 μm. The surface of this resist film was observed using an optical microscope to check for unpainted areas and the occurrence of striations.
Neither was approved. Further, when the surface roughness of the resist film was measured using Alpha Step-100 (TE, manufactured by NCOR), it was found to be as small as 30A (angstroms).

Further, the prepared photoresist composition was kept at a constant temperature of 40° C., and a time-lapse test (storage stability) for the generation of precipitates was conducted. Confirmation of precipitates in the aging test was performed by applying the solution onto a 4-inch silicon wafer using a spinner and observing the precipitates on the wafer using an optical microscope. When this solution was used, no precipitates were observed even after 2400 hours I'5lff had passed, and it was confirmed that the composition was completely stable.

Example 2 4-ethoxy-2-butanone (boiling point 153
A solution was prepared and evaluated in the same manner as in Example 1, except that the solution was used at When the applicability was examined, no unpainted areas or striations were observed. Moreover, the surface roughness of the resist film was as small as 50A. When a time test was conducted, no precipitates were observed up to 2000 hours.

Example 3 A solution was prepared in the same manner as in Example 1 except that 4-n-propoxy-2-butanone (boiling point 170°C) was used instead of 4-methoxy-4-methyl-2-pentanone in Example 1. prepared and evaluated. When the applicability was examined, no unpainted areas or striations were observed. Also,
The surface roughness of the resist film was as small as 30A. When a time test was conducted, no precipitates were observed up to 2000 hours.

Examples 4 to 20 Instead of 4-methoxy-4-methyl-2-pentanone in Example 1, a solution was prepared by mixing 20% of the total solvent amount of the solvent shown in Table 1, and the same procedure as in Example 1 was carried out. It was evaluated. When the applicability was examined, no unpainted areas or striations were observed. Further, the surface roughness of the resist film was as small as 30A. When a time test was conducted, 1s
No precipitate was observed until time oo.

Examples 21 to 34 100 parts by weight of novolak resin used in Example 1 and Table 2
26 parts by weight of the 1,2-naphthoquinone diazide photosensitive material shown in 4-methoxy-4-methyl-2-pentanone
A photoresist composition was prepared by dissolving 20 parts by weight and filtering through a 0°/20 μm microfilter, and evaluated in the same manner as in Example 1. When we investigated the applicability, we found that
In any of Examples 21 to 34, no unpainted areas or striations were observed. Moreover, the surface roughness of the resist film was as small as 50A. When a time-lapse test was conducted, no precipitates were observed in any of the samples even after 2400 hours.

Comparative Example 1 100 parts by weight of the novolak resin used in Example 1, and 2.
3. 26 parts by weight of naphthoquinonediazide-5-sulfonic acid ester of 4-trihydroxybenzophenone (average esterification rate 67%) was dissolved in 320 parts by weight of ethylene glycol monoethyl ether acetate to obtain 0.20
A photoresist composition was prepared by filtration using a μm microfilter, and evaluated in the same manner as in Example 1.

Although there was no unpainted area, striations were observed, and the surface roughness was as large as 300A.

When a time test was conducted, precipitates were observed after 600 hours.

Comparative Example 2 A photoresist composition was prepared in the same manner as in Comparative Example 1, except that ethyl lactate was used instead of the ethylene glycol monoethyl ether acetate used in Comparative Example 1! 111
+ manufactured and evaluated.

Although there was no unpainted area, there were large striations and the surface roughness was as high as 850A.

When a time-lapse test was conducted, precipitates were observed after 900 hours.

Comparative Example 3 A photoresist composition was prepared and evaluated in the same manner as in Comparative Example 1, except that diethylene glycol dimethyl ether was used instead of the ethylene glycol monoethyl ether acetate used in Comparative Example 1. There were no or no striations, but there was some residual paint. Surface roughness is 80A
Met.

When a time-lapse test was conducted, precipitates were observed after 900 hours.

Comparative Examples 4 to 14 Photoresist compositions were prepared and evaluated in the same manner as in Example 1 using the solvents shown in Table 3 instead of 4-methoxy-4-methyl-2-pentanone in Example 1.

When the coatability was examined, some uncoated areas occurred in Comparative Examples 5 and 13, but no uncoated areas were observed in the others, and no striations were observed. Surface roughness is Comparative Examples 6 and 7. 9. 1
0 was 12OA, and the others were 80A.

The results of the aging test are shown in Table 3. Both are 900
Precipitates were observed within hours.

Claims (1)

[Scope of Claims] (a) an alkali-soluble resin, (b) a 1,2-naphthoquinonediazide-4(or/and-5)-sulfonic acid ester, and (c) a compound represented by the general formula (I) and having a boiling point is 13
A positive photoresist composition comprising a ketoether solvent having a temperature of 0 to 170°C. General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ R_1: Alkylene group with 1 to 4 carbon atoms R_2: Straight chain or branched alkyl group with 1 to 3 carbon atoms