JP2003098659A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method using a radiation sensitive resin composition excellent in sensitivity, resolution, etc., and in suitability to coating particularly on a substrate of an increased diameter by a spin coating method and excellent also in shelf stability, capable of stable microfabrication and capable of giving a good pattern shape. SOLUTION: The pattern forming method comprises a step for forming a resist film on a substrate by coating a positive radiation sensitive resin composition comprising (a) an alkali-insoluble or slightly alkali-soluble resin which has been protected by an acid-decomposable group and is made alkali-soluble when the acid-decomposable group is decomposed, (b) a compound that generates an acid upon irradiation with radiation and (c) a mixed solvent comprising an alkyl lactate and a propylene glycol alkyl ether and/or a propylene glycol alkyl ether acetate, a step for irradiating the resist film with radiation and a step for developing the resist film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to ultraviolet rays, far ultraviolet rays, X rays.
Pattern forming method using radiation such as a beam or a charged particle beam.

[0002]

2. Description of the Related Art In the field of microfabrication represented by the manufacture of integrated circuits, miniaturization of the processing size in lithography is progressing in order to obtain a higher degree of integration of integrated circuits. A technique capable of stably performing the following fine processing is required. Therefore, it is necessary to accurately form a pattern of 0.5 μm or less in the resist used. Therefore, a lithography technique using shorter wavelength radiation has been studied. Examples of such radiation include ultraviolet rays typified by i rays (365 nm), far ultraviolet rays typified by KrF excimer lasers (248 nm), X rays typified by synchrotron radiation, and charged particle rays typified by electron beams. Etc. can be mentioned. In recent years, various resists corresponding to these radiations have been proposed. Of these, a resist that causes a reaction that changes the solubility in a developing solution due to the catalytic action of an acid generated by irradiation with radiation is usually attracting attention. Type resist ".

When a resist is actually used in the manufacturing process of an integrated circuit, a resist solution is usually prepared by dissolving a radiation-sensitive component such as a radiation-sensitive component or a film-forming resin component, which constitutes a “resist”, in a solvent. Then, spin coating or roll coating is applied to the substrate to be processed to form a resist film. Therefore, performances such as coating property and storage stability of the resist solution are indispensable performances for stably performing advanced fine processing. Further, the resist film forms a pattern suitable for fine processing by irradiating radiation, but the shape of the pattern at this time has an important influence on the accuracy of the fine processing, and a rectangular shape is preferable. There is.

In a resist using a novolac resin and a naphthoquinonediazide type photosensitizer used in conventional lithography, it is known to use ethylene glycol monoethyl ether acetate or the like as a solvent when preparing a resist solution. There is. However, regarding the "chemically amplified resist", there is a problem in storage stability when ethylene glycol monoethyl ether acetate is used as a solvent when preparing a resist solution. That is, when ethylene glycol monoethyl ether acetate is used as a solvent, there is a problem in that the sensitivity of the resist film and the shape of the formed pattern vary with the lapse of time after the preparation of the resist solution. Further, with the recent increase in the degree of integration of integrated circuits, in order to improve the yield and efficiency at the time of manufacturing integrated circuits, the diameter of the substrate (silicon wafer) has been increased, for example, from 4 inches to 6 inches and 8 inches. However, it can be said that the chemical amplification type resist using ethylene glycol monoethyl ether acetate, which is generally used as a solvent for the conventional chemical amplification type resist, does not necessarily have sufficient coatability by spin coating on a substrate having a large diameter. There wasn't.

[0005]

An object of the present invention is to provide a pattern forming method using an improved positive-type radiation-sensitive resin composition, which is excellent in sensitivity, resolution, etc., and particularly has a large diameter. It is to provide a pattern forming method using a positive radiation-sensitive resin composition suitable as a chemically amplified resist having excellent coating properties by spin coating on the formed substrate. Another object of the present invention is to provide a pattern forming method capable of stably performing fine processing and giving a good pattern shape. Still another object of the present invention is to provide a positive-type image having excellent storage stability, which has good resist sensitivity even after a long time has passed after the preparation of the resist solution and forms an excellent pattern shape with good reproducibility. It is intended to provide a pattern forming method using a radioactive resin composition. Further objects and advantages of the present invention will be apparent from the following description.

[0006]

According to the present invention, the above objects and advantages of the present invention are as follows. The positive type radiation sensitive resin composition of the following (a) is applied onto a substrate to form a resist film, This can be achieved by a pattern forming method, which comprises a step of developing the resist film after irradiating it with radiation.

(A) (a) An alkali-insoluble or sparingly alkali-soluble resin protected by an acid-decomposable group, which becomes alkali-soluble when the acid-decomposable group is decomposed (hereinafter,
It is referred to as "acid-decomposable group-containing resin". ), (B) a compound that generates an acid upon irradiation with radiation (hereinafter, referred to as “radiation-sensitive acid generator”), and (c) lactic acid alkyl ester (hereinafter, referred to as “lactic acid-based solvent”), and propylene. Positive type containing a mixed solvent containing glycol alkyl ether (hereinafter referred to as "propylene glycol ether solvent") and / or propylene glycol alkyl ether acetate (hereinafter referred to as "propylene glycol acetate solvent") Radiation-sensitive resin composition (hereinafter referred to as "resist composition (a)").

The resist composition (a) will be described below. Radiation-sensitive acid generator As the radiation-sensitive acid generator used in the present invention, that is, a compound that generates an acid in response to radiation, for example, an onium salt compound, a halogen-containing compound, a sulfone compound, and a sulfonate compound may be mentioned. You can More specifically, the following compounds can be mentioned.

A) Onium salts Iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, pyridinium salts and the like can be mentioned. Preferably, diphenyliodonium triflate, diphenyliodonium pyrene sulfonate, diphenyl iodonium dodecylbenzene sulfonate, triphenyl sulfonium triflate, triphenyl sulfonium hexafluoroantimonate, triphenyl sulfonium naphthalene sulfonate, (hydroxyphenyl) benzylmethyl sulfonium toluene sulfonate, etc. is there.

(A) Halogen-containing compounds Haloalkyl group-containing heterocyclic compounds, haloalkyl group-containing hydrocarbon compounds and the like can be mentioned. Preferably, phenyl-bis (trichloromethyl) -s-triazine, methoxyphenyl-bis (trichloromethyl)-
(Trichloromethyl) -s- such as s-triazine and naphthyl-bis- (trichloromethyl) -s-triazine
It is a triazine derivative or 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane.

C) Sulfone compounds β-ketosulfones, β-sulfonylsulfones and their α-diazo compounds can be mentioned. Preferred are phenacylphenyl sulfone, mesitylphenacyl sulfone, bis (phenylsulfonyl) methane, bis (phenylsulfonyl) diazomethane and the like.

D) Sulfonate compounds Alkyl sulfonates, haloalkyl sulfonates, aryl sulfonates, imino sulfonates and the like can be mentioned. Preferably, benzoin tosylate, tristriflate of pyrogallol, nitrobenzyl-9,10-diethoxyanthracene-2
-Sulfonates and the like.

These radiation-sensitive acid generators can be used alone or in admixture of two or more.

Acid-decomposable group-containing resin The acid-decomposable group-containing resin in the resist composition (a) is
For example, one or more substituents (hereinafter referred to as "acid-decomposable group") capable of decomposing an acidic functional group such as a phenolic hydroxyl group or a carboxyl group in an alkali-soluble resin described below in the presence of an acid to develop alkali solubility. Alkali-insoluble resin or alkali-insoluble resin obtained by substituting the. The term "alkali-insoluble" or "alkali-poorly-soluble" as used herein means that the resist composition under the alkaline developing conditions adopted when forming a resist pattern from a resist film formed using the resist composition (a). When the film formed by using only the acid-decomposable group-containing resin instead of (a) is developed, the initial film thickness of the film is 50
% Means the property that remains after development.

The acid-decomposable group is a phenolic hydroxyl group,
A group in which an acidic functional group such as a carboxyl group is substituted with at least one acid-decomposable group capable of decomposing in the presence of an acid, and the group decomposes in the presence of an acid to form a functional group exhibiting alkali solubility. It is not particularly limited as long as it is, for example, substituted methyl group, 1-substituted ethyl group, 1-branched alkyl group, silyl group, germyl group, alkoxycarbonyl group,
Examples thereof include an acyl group and a cyclic acid-decomposable group.

Examples of the substituted methyl group include methoxymethyl group, methylthiomethyl group, ethoxymethyl group,
Ethylthiomethyl group, methoxyethoxymethyl group, benzyloxymethyl group, benzylthiomethyl group, phenacyl group, bromophenacyl group, methoxyphenacyl group,
(Methylthio) phenacyl group, cyclopropylmethyl group, benzyl group, diphenylmethyl group, triphenylmethyl group, bromobenzyl group, nitrobenzyl group, methoxybenzyl group, methylthiobenzyl group, ethoxybenzyl group, ethylthiobenzyl group, piperonyl group Etc. can be mentioned.

The 1-substituted ethyl group is, for example, 1
-Methoxyethyl group, 1-methylthioethyl group, 1,1
-Dimethoxyethyl group, 1-ethoxyethyl group, 1-ethylthioethyl group, 1,1-diethoxyethyl group, 1-
Phenoxyethyl group, 1-phenylthioethyl group, 1,
1-diphenoxyethyl group, 1-benzyloxyethyl group, 1-benzylthioethyl group, 1-cyclopropylethyl group, 1-phenylethyl group, 1,1-diphenylethyl group, α-methylphenacyl group, etc. Can be mentioned.

Examples of the 1-branched alkyl group include isopropyl group, sec-butyl group, t-butyl group,
1,1-dimethylpropyl group, 1-methylbutyl group,
Examples thereof include a 1,1-dimethylbutyl group.

Examples of the silyl group include trimethylsilyl group, ethyldimethylsilyl group, diethylmethylsilyl group, triethylsilyl group, dimethylisopropylsilyl group, methyldiisopropylsilyl group, triisopropylsilyl group, t-butyldimethylsilyl group and diethylsilyl group. -T-
Butylmethylsilyl group, tri-t-butylsilyl group, dimethylphenylsilyl group, methyldiphenylsilyl group,
Examples thereof include a triphenylsilyl group.

Examples of the germyl group include trimethylgermyl group, ethyldimethylgermyl group, diethylmethylgermyl group, triethylgermyl group, dimethylisopropylgermyl group, methyldiisopropylgermyl group, triisopropylgermyl group, t-butyldimethylgermyl group, di-t-butylmethylgermyl group, tri-
t-butylgermyl group, dimethylphenylgermyl group,
Examples thereof include a methyldiphenylgermyl group and a triphenylgermyl group.

Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an isopropoxycarbonyl group, a t-butoxycarbonyl group and a t-pentyloxycarbonyl group.

Examples of the acyl group include acetyl group, propionyl group, butyryl group, heptanoyl group, hexanoyl group, valeryl group, pivaloyl group, isovaleryl group, lauriloyl group, myristoyl group, palmitoyl group, stearoyl group, oxalyl group and malonyl group. Group, succinyl group, glutaryl group, adipoyl group, piperoyl group, suberoyl group, azelaoil group, sebacyl group, acryloyl group, propioloyl group, methacryloyl group,
Crotonoyl group, oleoyl group, maleoyl group, fumaroyl group, mesaconoyl group, camphoroyl group, benzoyl group, phthaloyl group, isophthaloyl group, terephthaloyl group, naphthoyl group, toluoyl group, hydroatropoyl group, atropoyl group, cinnamoyl group, furoyl Group, thenoyl group, nicotinoyl group, isonicotinoyl group, toluenesulfonyl group, mesyl group and the like.

Examples of the cyclic acid-decomposable group include cyclopropyl group, cyclopentyl group, cyclohexyl group,
Cyclohexenyl group, oxocyclohexenyl group, 4-
Methoxycyclohexyl group, tetrahydropyranyl group,
Tetrahydrofuranyl group, tetrahydrothiopyranyl group, tetrahydrothiofuranyl group, 3-bromotetrahydropyranyl group, 4-methoxytetrahydropyranyl group, 4-methoxytetrahydrothiopyranyl group, S, S
-Dioxide group, 2-1,3-dioxolanyl group, 2-
Examples thereof include a 1,3-dithiolanyl group, a benzo-2-1,3-dioxolanyl group, a benzo2-1,3-dithiolanyl group, and the like.

Among these acid-decomposable groups, t-butyl group, benzyl group, t-butoxycarbonyl group, tetrahydropyranyl group, tetrahydrofuranyl group, tetrahydrothiopyranyl group, tetrahydrothiofuranyl group and the like are preferable.

The introduction rate of acid-decomposable groups in the acid-decomposable group-containing resin (the ratio of the number of acid-decomposable groups to the total number of acidic functional groups and acid-decomposable groups in the acid-decomposable group-containing resin) is , Preferably 15 to 100%, more preferably 20 to 10
0%, particularly preferably 20 to 80%.

The polystyrene-reduced weight average molecular weight (hereinafter referred to as "Mw") of the acid-decomposable group-containing resin measured by gel permeation chromatography is preferably 1,000 to 150,000, and more preferably 3. 1,000 to 100,000.

The acid-decomposable group-containing resin is a resin having one or more acid-decomposable groups, for example, by introducing one or more acid-decomposable groups into one or more preliminarily prepared alkali-soluble resins. It can be produced by polymerization or copolymerization of a monomer or polycondensation or copolycondensation of a polycondensation component having one or more acid-decomposable groups.

These acid-decomposable group-containing resins can be used alone or in admixture of two or more.

The ratio of the radiation-sensitive acid generator to the acid-decomposable group-containing resin in the resist composition (a) is preferably such that the radiation-sensitive acid generator is 100 parts by weight of the acid-decomposable group-containing resin. The amount is 0.05 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight. If the amount of the radiation-sensitive acid generator is less than 0.05 parts by weight, it may be difficult to effectively cause a chemical change due to the catalytic action of the acid generated by irradiation of radiation, and more than 20 parts by weight. If so, there is a possibility that coating unevenness may occur when the resist composition (a) is applied, or scum may occur during development.

Alkali-Soluble Resin The alkali-soluble resin has a functional group having an affinity with an alkali developer, for example, an acidic functional group such as a phenolic hydroxyl group and a carboxyl group, and is not particularly limited as long as it is soluble in the alkali developer. It is not something that will be done.

As such an alkali-soluble resin,
For example, hydroxystyrene, hydroxy-α-methylstyrene, vinylbenzoic acid, carboxymethylstyrene,
Cleavage of the polymerizable double bond of at least one monomer having an acidic functional group such as carboxymethoxystyrene, (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid and cinnamic acid. Examples thereof include a vinyl resin having a repeating unit and a condensation resin having a repeating repeating unit having an acidic functional group represented by novolak resin.

When the alkali-soluble resin is the vinyl-based resin, the resin may be composed only of repeating units in which the polymerizable double bond of the monomer having the acidic functional group is cleaved, As long as the above resin is soluble in an alkali developing solution, it may further have other repeating units, if necessary.

Examples of such other repeating units include styrene, α-methylstyrene, vinyltoluene, maleic anhydride, (meth) acrylonitrile, crotonnitrile, maleinnitrile, fumaronitrile, mesaconnitrile, citraconnitrile and itaconenitrile. ,
(Meth) acrylamide, crotonamide, maleamide, fumaramide, mesacone amide, citracone amide, itaconamide, vinylaniline, vinylpyridine, vinyl-ε-caprolactam, vinylpyrrolidone,
An example is a unit in which a polymerizable double bond portion of a monomer having a polymerizable double bond such as vinylimidazole is cleaved.

Polymerization or copolymerization for producing the alkali-soluble resin composed of the vinyl resin is carried out by radical polymerization initiator, anion polymerization catalyst, coordination anion polymerization catalyst, depending on the kind of the monomer and the reaction medium. A polymerization initiator such as a cationic polymerization catalyst or a polymerization catalyst is appropriately selected, and bulk polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization, bulk polymerization
It can be carried out in an appropriate polymerization mode such as suspension polymerization.

When the alkali-soluble resin is the condensation resin, the resin may be composed of, for example, only a novolac resin unit, but as long as the produced resin is soluble in the alkali developing solution, It is possible to further have other condensation units. Such a condensation-type resin contains one or more phenols and one or more aldehydes, optionally together with a polycondensation component capable of forming another condensation-type repeating unit, in an aqueous medium in the presence of an acidic catalyst. Alternatively, it can be produced by polycondensation or copolycondensation in a mixed medium of water and a hydrophilic solvent.

In this case, examples of the phenols include o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol,
2,5-xylenol, 3,4-xylenol, 3,5
-Xylenol, 2,3,5-trimethylphenol,
Examples of the aldehydes include formaldehyde, trioxane, paraformaldehyde, benzaldehyde, acetaldehyde, propylaldehyde, and 3,4,5-trimethylphenol.
Examples thereof include phenylacetaldehyde.

Although the content of the repeating unit having an acidic functional group in the alkali-soluble resin cannot be unconditionally specified depending on the kind of other repeating units contained as necessary,
Usually 15 to 100 mol%, more preferably 20 to 1
It is 00 mol%.

When the alkali-soluble resin has a repeating unit containing a carbon-carbon unsaturated bond, it can also be used as a hydrogenated product. The hydrogenation rate in this case is usually the carbon-carbon unsaturated bond contained in the repeating unit,
It is 70% or less, preferably 50% or less, more preferably 40% or less. When the hydrogenation rate exceeds 70%, the developing property of the alkali-soluble resin with an alkali developing solution tends to deteriorate.

Dissolution Control Agent A dissolution control agent may be added to the resist composition (a). In this case, the addition amount of the dissolution control agent is 50 parts by weight based on 100 parts by weight of the acid-decomposable group-containing resin. It is preferably not more than part.

Examples of the dissolution control agent include compounds in which an acidic functional group such as a phenolic hydroxyl group or a carboxyl group is substituted with the above-mentioned acid-decomposable group.

Preferred dissolution control agents include polyphenolic compounds such as bisphenol A, bisphenol F and bisphenol S, and compounds in which the above acid-decomposable group is introduced into a carboxylic acid compound such as hydroxyphenylacetic acid. .

Specific examples thereof include compounds represented by the following chemical formula (a) or (b).

[0043]

[Chemical 1]

Solvent The solvent used in the resist composition (a) is a mixed solvent containing a lactic acid-based solvent and a propylene glycol ether-based solvent and / or a propylene glycol acetate-based solvent. Such a solvent imparts excellent storage stability to the resist composition (a) and gives a good resist pattern shape with good reproducibility even after a long time has passed after the preparation of the resist composition (a). It is possible.

The lactic acid-based solvent used in the present invention includes
For example, alkyl esters of lactic acid having 1 to 6 carbon atoms such as methyl lactate, ethyl lactate, and butyl lactate can be preferably used, and ethyl lactate can be more preferably used.

The propylene glycol ether solvent used in the present invention is propylene glycol alkyl ether, and the propylene glycol alkyl ether means propylene glycol monoalkyl ether and / or propylene glycol dialkyl ether.

Propylene glycol in the propylene glycol ether solvent has two kinds of isomers, a 1,2-dihydroxy compound and a 1,3-dihydroxy compound, and the 1,2-dihydroxy compound has a monoalkyl ether of its isomer. Since the structure also has two kinds of isomers, one propylene glycol monoalkyl ether has a total of three kinds of isomers. Similarly, in the case of dialkyl ether, there are up to three isomers,
When two alkyl groups are the same, there are two isomers.

As the alkyl ether group of propylene glycol, a lower alkyl ether having 1 to 6 carbon atoms can be preferably used, and preferred examples of the alkyl ether include methyl ether, ethyl ether, propyl ether, butyl ether and the like. Particularly preferred are methyl ether, ethyl ether and the like . In the present invention, the propylene glycol monoalkyl ether or the propylene glycol dialkyl ether can be preferably used in the same manner even if the type of the alkyl ether moiety or the type of the isomer is single or a mixture of several types. . Further, a mixture of a monoether body and a diether body can be preferably used.

Specific examples of such a solvent include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether. , Propylene glycol dibutyl ether and the like , and preferably propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether and propylene glycol diethyl ether can be mentioned. The propylene glycol ether solvents can be used alone or in combination of two or more.

The propylene glycol acetate solvent used in the present invention means propylene glycol alkyl ether acetate. Similar to propylene glycol ether-based solvent, propylene glycol in propylene glycol acetate-based solvent
Since there are two kinds of isomers, a 2-dihydroxy body and a 1,3-dihydroxy body, and the 1,2-dihydroxy body also has two kinds of isomers in the structure of its monoalkyl ether acetate. There are a total of three isomers of propylene glycol monoalkyl ether acetate. In the present invention, the propylene glycol alkyl ether acetate can be preferably used in the same manner even if the type of the alkyl ether moiety or the type of the isomer is single or a mixture of several types.

As the alkyl ether group of propylene glycol, a lower alkyl ether having 1 to 6 carbon atoms, which is mentioned as an example of the propylene glycol ether type solvent, can be suitably used, and the preferable alkyl ether is methyl ether or ethyl ether. Ethers, propyl ethers, butyl ethers and the like, and particularly preferable ones are methyl ethers, ethyl ethers and the like.

As such a propylene glycol acetate solvent, for example, a lower alkyl ether acetate of propylene glycol having 1 to 6 carbon atoms such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, etc. It can be preferably used. Particularly preferred is propylene glycol monomethyl ether acetate. The propylene glycol acetate solvent can be used alone or in combination of two or more kinds.

The mixing ratio of these lactic acid type solvent and propylene glycol ether type solvent and / or propylene glycol acetate type solvent is such that the total amount of the mixed solvent is 10
The proportion of the lactic acid-based solvent in 0 part by weight is preferably 30 to 95 parts by weight.

In the present invention, a mixed solvent of a lactic acid-based solvent and a propylene glycol ether-based solvent and / or a propylene glycol acetate-based solvent is mixed with another solvent, for example, less than 70% by weight, preferably 50% by weight of the total amount of the solvent.
Can be mixed in the range of less than 30% by weight, particularly preferably less than 30% by weight.

Examples of the other solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether and the like; ethylene glycol monomethyl ether acetate, ethylene glycol. Ethylene glycol monoalkyl ether acetates such as monoethyl ether acetate; Diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether; Aromatic hydrocarbons such as toluene and xylene; methyl ethyl ketone, 2
-Ketones such as heptanone, 3-heptanone, 4-heptanone, cyclohexanone; ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2
-Methyl hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate,
Ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate,
Esters such as 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, ethyl pyruvate; N-methylpyrrolidone,
Examples thereof include amide solvents such as N, N-dimethylformamide, N-methylformamide and N, N-dimethylacetamide. These solvents may be used alone or in admixture of two or more.

The total amount of the solvents is usually 20 to 3,000 parts by weight, preferably 50 to 3,000 parts by weight, and more preferably 100 to 2 parts by weight, based on 100 parts by weight of the acid-decomposable group-containing resin. 1,000 parts by weight.

If necessary, the resist composition (a) may contain
Various additives such as surfactants and sensitizers can be added.

The surfactant is used in the resist composition (a).
It has the effect of improving the coating property, striation, and developability of the resist. Examples of such a surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether,
In addition to polyoxyethylene glycol dilaurate and polyoxyethylene glycol distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No.
75, No95 (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), F-top EF301, EF303, EF352 (Tochem Products), Megafac F171, F172, F173.
(Manufactured by Dainippon Ink and Chemicals), Florard FC430,
FC431 (Sumitomo 3M), Asahi Guard AG7
10, Surflon S-382, SC-101, SC-1
02, SC-103, SC-104, SC-105, S
C-106 (manufactured by Asahi Glass) and the like can be mentioned.

The content of the surfactant is usually 2 parts by weight or less based on 100 parts by weight of all the resin components in the resist composition (a).

The sensitizer absorbs the energy of radiation and transmits the energy to the radiation-sensitive acid generator,
It has the effect of increasing the amount of acid produced by it,
It has the effect of improving the sensitivity of the resist obtained using the resist composition (a). Preferred specific examples of the sensitizer include acetone, benzene, acetophenones, benzophenones, naphthalene, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines.

The compounding amount of the sensitizer is such that the resist composition (a)
The amount is usually 50 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of all the resin components.

By adding a dye or a pigment, the effect of halation during irradiation of radiation can be mitigated, and by adding an adhesion aid, the adhesion to the substrate can be improved. Furthermore, examples of other additives include antihalation agents such as azo compounds and amine compounds, storage stabilizers, defoamers, and shape improvers.

The resist composition (a) is prepared, for example, by filtering a solution having a solid content concentration of 5 to 50% by weight with a filter having a pore size of about 0.2 μm.

Pattern forming operation The operation for forming a pattern from the resist composition (a) is as follows.
The method includes the steps of applying the resist composition (a) on a substrate to form a resist film, irradiating the resist film with radiation, and then developing. More specifically, the resist composition (a) is applied onto a substrate such as a silicon wafer or a wafer covered with aluminum by a means such as spin coating, cast coating, or roll coating to form a resist coating. And irradiating the resist film with radiation so as to form a desired pattern. Radiation used in that case, depending on the type of radiation-sensitive acid generator used,
UV rays such as i-rays; far-ultraviolet rays such as excimer lasers; X-rays such as synchrotron radiation; charged particle rays such as electron beams are appropriately selected and used. Further, the radiation irradiation conditions such as the radiation dose are appropriately selected according to the compounding composition of the resist composition (a), the type of additives and the like.

When forming a pattern using the resist composition (a), a protective film may be provided on the resist film in order to prevent the influence of basic impurities contained in the working atmosphere. .

Further, in the present invention, in order to improve the apparent sensitivity of the resist film, it is preferable to perform baking after irradiation with radiation. The heating condition is usually 30 to 200 ° C., preferably 50 to 150 ° C., though it varies depending on the compounding composition of the resist composition (a), the kind of additives and the like.

Then, a predetermined pattern is formed by developing with an alkali developing solution. Examples of the alkaline developer include sodium hydroxide, potassium hydroxide,
Sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium Hydroxide, choline, pyrrole, piperidine, 1,8-diazabicyclo- [5,4,0] -7-undecene, 1,5
An alkaline aqueous solution in which an alkaline compound such as diazabicyclo- [4,3,0] -5-nonene is dissolved to a concentration of usually 1 to 10% by weight, preferably 2 to 5% by weight is used.

A suitable amount of a water-soluble organic solvent such as methanol or ethanol and a surfactant may be added to the developer. When a developing solution composed of an alkaline aqueous solution is used, it is generally washed with water after development.

[0069]

EXAMPLES The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In the examples, various characteristics were evaluated as follows.

Mw Tosoh Corp. GPC column (2 G2000H _XL ,
G3000H _{XL (} 1 bottle, G4000H _XL 1 bottle) was used, and the flow rate was 1.0 ml / min, the elution solvent was tetrahydrofuran, and the column temperature was 40 ° C. Coating Property The radiation-sensitive resin composition was spin-coated on a 6-inch silicon wafer and baked at 90 ° C. for 2 minutes, and then the formed resist film was observed. The case where there was no coating unevenness, cloudiness and foreign matter and the surface smoothness was high was defined as good. The sensitivity was defined as the radiation dose at which a line-and-space pattern with a sensitivity of 0.5 μm could be formed as designed. The unit is J / m ² . Amount of film reduction The film thickness of the resist film before and after development was measured and calculated by α-step manufactured by Tencor.

Synthesis Example 1 30 g of polyhydroxystyrene was dissolved in tetrahydrofuran, 10 g of potassium t-butoxide was added, and di-t-butyl dicarbonate 60 was added at 0 ° C. with stirring.
g was added dropwise and reacted for 4 hours. After the reaction was completed, this solution was dropped into water, and the precipitated resin was dried in a vacuum dryer at 50 ° C.
Dried overnight. The resin obtained has an Mw of 15,000.
From the result of NMR measurement, it was a structure in which 29% of hydrogen atoms of the phenolic hydroxyl group were substituted with t-butoxycarbonyl group. This resin is called resin (I).

Example 1 and Comparative Example 1 The solvent shown in Table 1 was mixed with the other components shown in Table 1, and the mixture was subjected to microfiltration with a 0.2 μm filter to remove foreign matters to give a positive type impression. A radioactive resin composition was obtained.
The positive-type radiation-sensitive resin composition thus obtained was spin-coated on a 6-inch silicon wafer and then baked at 100 ° C. for 2 minutes to irradiate the formed resist film with a thickness of 1 μm through a mask. did. Here, a KrF excimer laser irradiation device (MBK-400TL-N) manufactured by Admon Science Co. was used for irradiation. After that, baking is performed at 110 ° C. for 2 minutes, and 60% with a 2.38 wt% tetramethylammonium hydroxide aqueous solution.
The pattern was formed by developing for 23 seconds at 23 ° C. and then rinsing with water for 30 seconds. The formation of the pattern using the positive-type radiation-sensitive resin composition was performed for the same composition immediately after preparation and after 30 days from preparation. The obtained results are shown in Table 1.

The mixing ratio (weight ratio) of each component to the solvent in Example 1 and Comparative Example 1 was resin 100, radiation-sensitive acid generator 3, and solvent 420. The radiation-sensitive acid generator and solvent in Table 1 are as follows. Radiation-sensitive acid generator Triphenylsulfonium triflate

Solvent EL: Ethyl lactate PGMEA: Propylene glycol monomethyl ether acetate ECA: Ethylene glycol monoethyl ether acetate

[0075]

[Table 1]

[0076]

According to the pattern forming method of the present invention, the resist composition (a) used is excellent in sensitivity, resolution, etc., particularly excellent in coatability by spin coating on a substrate having a large diameter, and stable in storage. The pattern forming method of the present invention can be applied to ultraviolet rays such as i-line, deep ultraviolet rays such as excimer laser, and synchro. It can be applied to any of radiations such as X-rays such as tron radiation and charged particle beams such as electron beams, and can be advantageously used particularly for manufacturing a semiconductor device which is expected to be further miniaturized in the future.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H025 AA01 AA02 AB16 AC01 AC04                       AC05 AC06 AC08 AD03 BE00                       BG00 CC03 EA05 FA03 FA12                       FA17

Claims (4)

[Claims] 1. A resin which is protected by an acid-decomposable group and is alkali-insoluble or sparingly soluble in alkali, and becomes alkali-soluble when the acid-decomposable group is decomposed, and (b) an acid by irradiation with radiation. And a positive-type radiation-sensitive resin composition containing a mixed solvent containing (c) lactic acid alkyl ester and propylene glycol alkyl ether and / or propylene glycol alkyl ether acetate. To form a resist film, and after irradiating the resist film with radiation,
A pattern forming method comprising a step of developing. 2. The pattern forming method according to claim 1, wherein the mixed solvent (c) contains an alkyl lactate ester and a propylene glycol alkyl ether acetate. 3. The pattern forming method according to claim 1, wherein the ratio of the alkyl lactate ester in 100 parts by weight of the total amount of the mixed solvent (c) is 30 to 95 parts by weight. 4. The pattern forming method according to claim 1, wherein the mixed solvent (c) contains ethyl lactate and propylene glycol monomethyl ether acetate.