JP2000275835A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a resist pattern of a good shape with high sensitivity and high resolution. SOLUTION: A photosensitive resin composition containing a resin whose alkali solubility is increased by the action of an acid, a compound which generates an acid by exposure, a basic compound and a solvent is applied on a substrate and dried to form a photosensitive layer and an acidic antireflection film is formed on the substrate under the photosensitive layer in contact with the layer or on the photosensitive layer. The photosensitive layer is selectively exposed with far UV and the exposed part of the photosensitive layer is removed by developing the layer to form the objective pattern. The pKa of the basic compound is >=7.70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a pattern forming method using a radiation-sensitive photosensitive resin composition, and more particularly to a pattern forming method for producing a semiconductor integrated circuit.

[0002]

2. Description of the Related Art High integration of a semiconductor integrated circuit has progressed at a speed four times as fast as three years as generally known.
Accordingly, the demand for photolithography technology, which is indispensable for the production of integrated circuits, is increasing year by year. For example, in the case of a dynamic random access memory (DRAM), the production of a 256 Mbit DRAM requires a lithography technology of a 0.25 μm level. For this reason, the wavelength used for exposing the photoresist has been shortened from the g-line (436 nm) of the mercury lamp to the i-line (365 nm) and further to the KrF excimer laser beam (248 nm).

For example, in the case of a positive type photoresist, a resist using a naphthoquinonediazide as a photosensitizing agent has conventionally been used. However, this positive type resist has a low transmittance with respect to light in a deep ultraviolet region such as a KrF excimer laser beam. It has low sensitivity and low resolution. As a new positive resist that solves such a problem, various chemically amplified positive photoresists have been proposed.

A chemically amplified positive resist is a resin having an effect of suppressing dissolution in an alkali developing solution by introducing an acid labile group which is deprotected by the action of an acid into a resin soluble in an alkali developing solution. And a photosensitive composition containing a photoacid generator. When this composition is irradiated with light, an acid is generated from the photoacid generator, and by heating after exposure (post-exposure bake, hereinafter referred to as PEB), the acid removes the substituent which had given the dissolution inhibitor effect. Let go. As a result, the exposed portion becomes alkali-soluble, and a positive resist pattern is obtained by treating with an alkali developing solution.
At this time, the acid acts as a catalyst and exerts its effect in a very small amount. In addition, the movement of the acid is activated by PEB, and the chemical reaction is promoted in a chain reaction, thereby improving the sensitivity.

It has been known that the inclusion of a basic compound such as an amino compound in such a chemically amplified positive resist eliminates the T-type pattern caused by the formation of a hardly soluble layer on the surface of the resist pattern. (For example, Japanese Patent Application Laid-Open No. 7-92678). On the other hand, with the miniaturization of patterns, the effect of standing waves due to interference between incident light and reflected light during exposure cannot be ignored. Specifically, irregularities on the side walls of the resist pattern due to standing waves,
It appears as a problem such as sensitivity fluctuation when the resist film thickness changes.

As a method for solving the problem of the standing wave, there is a method of forming an antireflection film between a substrate and a resist film or on an upper layer of the resist film and then exposing the resist to form a pattern. However, there is no known effect of a basic compound in a photosensitive composition when a pattern is formed using an antireflection film.

[0007]

Many of the above antireflection films have acidic properties as described in JP-A-9-291228. By the way, a resin having a dissolution inhibiting effect on an alkali developer by introducing an acid labile group which is deprotected by the action of an acid on a resin soluble in an alkali developer, and a chemical containing a photoacid generator. In the case of an amplification type positive resist, when a pattern is formed using an antireflection film having such an acidic property, an acid component in the antireflection film causes an acid component in the resist near the interface between the resist film and the antireflection film. Of the protective group of the resin, the resist film in that portion becomes easily soluble in an alkali developing solution, and when an acid antireflection film is provided on the resist film, the residual film ratio of the resist pattern decreases, It was also found that when an acidic anti-reflection film was provided under the resist film, penetration into the lower portion of the resist pattern (hereinafter referred to as undercut) occurred.

An object of the present invention is to solve such a problem, to provide a pattern forming method which is free from the effects of standing waves, has a good residual film ratio of resist and a good pattern shape, and can obtain practical sensitivity and high resolution. To provide.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve such a problem. As a result, when an acidic antireflection film is used, a specific pKa as a basic compound contained in the photosensitive resin composition is used. It has been found that the use of the compound (1) has no effect of standing waves, has a good residual film ratio of the resist and a good pattern shape, and achieves practical sensitivity and high resolution, and has reached the present invention.

That is, the gist of the present invention is that (1)
(A) a resin whose alkali solubility is increased by the action of an acid,
(B) a step of applying a photosensitive resin composition containing a compound that generates an acid upon exposure to light, (c) a basic compound and (d) a solvent, and drying to form a photosensitive layer; Forming an acidic anti-reflection film on the lower or upper part in contact with the photosensitive layer, (3) selectively exposing the photosensitive layer with far ultraviolet rays, and (4) developing the photosensitive layer. A pattern forming method comprising a step of forming a pattern by removing an exposed portion of the photosensitive layer, wherein the pKa of the basic compound is 7.70 or more.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present invention provides a method for forming a pattern, which will be described in detail later,
The photosensitive resin composition contains a basic compound having a pKa of 7.70 or more. First, the photosensitive resin composition will be described below. In the present invention, as a resin whose alkali solubility is increased by the action of an acid (hereinafter, referred to as the resin of the present invention), an exposed portion becomes alkali-soluble at the time of development, is eluted in an alkali developing solution, and has a uniform resist film forming ability. Any one can be used, for example, novolak resin, polyhydroxystyrenes such as a resin obtained by polymerization of hydroxystyrene alone or copolymerization of hydroxystyrene and various vinyl monomers, and ethylenic resins such as acrylic acid. Polymers of carboxylic acids containing saturated double bonds alone or polyacryls obtained by copolymerizing carboxylic acids containing ethylenically unsaturated double bonds such as acrylic acid with hydroxystyrenes or various vinyl monomers Of phenolic hydroxyl and / or carboxyl group-containing resins such as acids It can be used Lumpur hydroxyl and / or at least a portion was protected with an acid labile group resin of carboxyl group. Here, polyhydroxystyrenes may be homopolymerized or copolymerized as long as they are polymers having a structure derived from hydroxystyrene as a partial structure, or have a substituent on the benzene ring or in other portions. Including those that are. In the case of novolak resin, the phenol component is phenol,
o-cresol, m-cresol, p-cresol, resorcinol, pyrogallol, xylenol and the like can be used, and as the aldehyde or ketone component, formaldehyde, acetaldehyde, benzaldehyde,
Acetone or the like can be used. As the vinyl monomer copolymerized with hydroxystyrene, a compound containing an ethylenically unsaturated double bond such as acrylic acid, vinyl alcohol, or a derivative thereof can be used.

The polyhydroxystyrenes include o-
Hydroxystyrenes such as hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (o-hydroxyphenyl) propylene, 2- (m-hydroxyphenyl) propylene and 2- (p-hydroxyphenyl) propylene, or Resins obtained by polymerizing two or more kinds, or hydroxystyrenes and acrylic acid, methacrylic acid, acrylic acid esters or methacrylic esters in the presence of a radical polymerization initiator, a cationic polymerization initiator or an anionic polymerization initiator, and the like. . Hydrogenated ones for reducing the absorbance can also be preferably used. Among them, particularly, polyhydroxystyrenes and polyacrylic acids can be usefully used in terms of absorption of light from an exposure light source.

The preferred weight average molecular weight of the resin whose alkali solubility is increased by the action of an acid is 1,000 to 100,000 in terms of polystyrene by GPC measurement. Below this range, the applicability of the composition will decrease, and above this range, the alkali solubility of the exposed areas will tend to decrease. In particular, in combination with the specific basic compound of the present invention described below, the resolution, the pattern cross-sectional shape is good, particularly preferred in achieving the effect of the present invention that the pattern shape is not deteriorated by standing waves Is from 1,500 to 5,
It is 0000.

As the acid labile group, any group can be used as long as it is eliminated by an acid generated upon exposure to generate an alkali-soluble group such as a phenolic hydroxyl group or a carboxylic acid. -Methoxyethoxy group, 1-methoxypropyloxy group, 1
-Methoxybutyloxy group, 1-ethoxyethoxy group,
1-ethoxypropyloxy group, 1-ethoxybutyloxy group, 1- (n-butoxy) ethoxy group, 1- (is
o-butoxy) ethoxy group, 1- (sec-butoxy)
An ethoxy group, a 1- (tert-butoxy) ethoxy group,
Acetal groups such as 1- (cyclohexyloxy) ethoxy group, tetrahydrofuranyloxy group and tetrahydropyranyloxy group; ketal groups such as 1-methoxy-1-methylmethoxy group and 1-methoxy-1-methylethoxy group; methoxycarbonyl Oxy group, ethoxycarbonyloxy group, n- (propyloxycarbonyloxy group, iso-propyloxycarbonyloxy group, n-
Butoxycarbonyloxy group, sec-butoxycarbonyloxy group, iso-butoxycarbonyloxy group,
Carbonate groups such as a t-butoxycarbonyloxy group and a menthyloxycarbonyloxy group are used. (In the present specification, the acid labile group includes a phenolic hydroxyl group or a carboxylic acid-derived oxygen atom.) The number of carbon atoms of the acetal group is usually 2 to 20, preferably 2 to 2.
The number of carbon atoms of the ketal group is usually 2 to 20, preferably 4 to 10, and the number of carbon atoms of the carbonate group is usually 2 to 20, preferably 2 to 12.

More preferred are an acetal group and a carbonate group, and further preferred are an ethoxyethoxy group, a tetrahydrofuranyloxy group, a tetrahydropyranyloxy group, an ethoxycarbonyloxy group and an iso-
A propyloxycarbonyloxy group and a t-butoxycarbonyloxy group. These acid labile groups may be used alone, or two or more kinds may be used in combination. When two or more kinds are used in combination, each acid labile group is present on a separate polymer molecular chain. May also be present on the same polymer molecular chain.

The protection ratio of the resin having a phenolic hydroxyl group and / or a carboxyl group such as polyhydroxystyrenes and polyacrylic acids with an acid labile group of the phenolic hydroxyl group and the carboxyl group is not particularly limited. Is preferred, especially 10 to 50 mol%
Is preferred. If the protection ratio is smaller than the above range, the residual film ratio of the unexposed portion of the resist film tends to decrease, and the resolution tends to decrease. On the other hand, if the protection ratio is larger than the above range, the developer may be repelled at the time of development, and the development may not be performed.

In the present invention, the basic compound contained in the photosensitive resin composition must have a pKa of 7.70 or more. The preferred pKa range of the basic compound is 7.70.
It is 12 or less. A more preferred range of the lower limit is 7.7.
It is 5 or more, and a preferable range of the upper limit is 11 or less.
If the pKa value is less than 7.70, sufficient resistance to the acidic antireflection film cannot be obtained, resulting in a decrease in the residual resist film ratio and a deterioration in the pattern shape. If the pKa value is too large, the sensitivity tends to decrease.

Examples of the basic compound having a pKa of 7.70 or more in the present invention include, for example, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine and the like. Alkylamines, diamines such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,8-diaminooctane, N, N, N ', N'-tetramethylethylenediamine, ethanolamine, diethanolamine , Triethanolamine, iso-propanolamine, di-iso-propanolamine, tri-is
o-propanolamine, N, N-bis-iso-propanol-n-propylamine, 2,3-dimethyl-4
-Hydroxyethylamine, 2,2-dimethyl-4-hydroxyethylamine, 3,3-dimethyl-4-hydroxyethylamine, bis (2,3-dimethyl-4-hydroxyethyl) amine, bis (2,2-dimethyl-4 −
Hydroxyethyl) amine, bis (3,3-dimethyl-
4-hydroxyethyl) amine, tris (2,3-dimethyl-4-hydroxyethyl) amine, bis (2-hydroxyethyl) iminobis (hydroxymethyl) ethane, bis (2-hydroxyethyl) iminotris (hydroxymethyl) methane, etc. Such as hydroxyalkylamines, morpholine, piperazine, piperidine, pyrrolidine, 1-methylperidine, 1,2-dimethylpiperidine, 1,2-dimethylpyrrolidine, 1,2,2,4-tetramethylpiperidine, N-methylpyrrolidine, etc. Aliphatic amines such as cyclic amines; 4-aminopyridine,
Benzylamine, N-methylbenzylamine, N, N-
Examples thereof include aromatic ring-containing amines such as dimethylbenzylamine and phenethylamine, and derivatives thereof.

The basic compound of the present invention is added in an amount of usually 0.0001 to 5 parts by weight, preferably 0.001 to 2 parts by weight of the basic compound of the present invention per 100 parts by weight of the resin of the present invention.
Used in parts by weight. When the basic compound is used in an amount in the above range, a sufficient resistance effect to the acidic antireflection film can be obtained, and a favorable resist pattern can be obtained, which is preferable.
However, if the amount is excessive, the sensitivity of the resist tends to decrease.

The compound that generates an acid upon exposure (hereinafter referred to as a photoacid generator) used in the present invention is not particularly limited as long as it generates an acid by the action of light used for exposure. Instead, those which are conventionally known can be used. Specifically, for example, tris (trichloromethyl) -s-triazine, tris (tribromomethyl) -s-triazine, tris (dibromomethyl)-
s-Triazine, 2,4-bis (tribromomethyl)-
Halogen-containing s-triazine derivatives such as 6-methoxyphenyl-s-triazine, halogens such as 1,2,3,4-tetrabromobutane, 1,1,2,2-tetrabromoethane, carbon tetrabromide and iodoform Halogen-substituted cycloparaffinic hydrocarbons such as substituted paraffin hydrocarbons, hexabromocyclohexane, hexachlorocyclohexane, and hexabromocyclododecane; halogen-containing benzene derivatives such as bis (trichloromethyl) benzene and bis (tribromomethyl) benzene; tribromomethyl Halogen-containing sulfone compounds such as phenylsulfone, trichloromethylphenylsulfone, and 2,3-dibromosulfolane; tris (2,3-dibromopropyl)
Halogen-containing isocyanurate derivatives such as isocyanurate, triphenylsulfonium chloride, triphenylsulfonium methylsulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium-p-toluenesulfonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroarcete , Sulfonium salts such as triphenylsulfonium hexafluorophosphonate, diphenyliodonium chloride,
Iodonium salts such as diphenyliodonium methylsulfonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium-p-toluenesulfonate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroarsenate, diphenyliodonium hexafluorophosphonate, p-toluenesulfonic acid Methyl, ethyl p-toluenesulfonate, butyl p-toluenesulfonate, phenyl p-toluenesulfonate, 1,2,3-tri (p-toluenesulfonyl) benzene, p-toluenesulfonic acid benzoin ester, ethyl methanesulfonate Butyl methanesulfonate, 1,2,3-tri (methanesulfonyl) benzene, phenyl methanesulfonate,
Methanesulfonic acid benzoin ester, methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, butyl trifluoromethanesulfonate, 1,2,2
3-tri (trifluoromethanesulfonyl) benzene,
Sulfonates such as phenyl trifluoromethanesulfonate and benzoin trifluoromethanesulfonate, disulfones such as diphenyldisulfone, bis (cyclohexylsulfonyl) methane, bissulfonylmethanes such as bis (phenylsulfonyl) methane, o-nitrobenzyl O-Nitrobenzyl esters such as -p-toluenesulfonate; and sulfone hydrazides such as N, N'-di (phenylsulfonyl) hydrazide.

It is also effective to use a compound having a bissulfonylmethane skeleton, in particular, a bissulfonyldiazomethane compound represented by the following general formula (I) as a photoacid generator.

[0022]

Embedded image

(Wherein R ¹ and R ² independently represent a linear, branched or cyclic alkyl group which may have a substituent or an aryl group which may have a substituent ). As specific examples, for example, bis (cyclohexylsulfonyl) diazomethane, cyclohexylsulfonylethylsulfonyldiazomethane, bis (iso-propylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (sec-butylsulfonyl)
Diazomethane, tert-butylsulfonylmethylsulfonyldiazomethane, tert-butylsulfonylcyclohexylsulfonyldiazomethane, bis (cyclopentylsulfonyl) diazomethane, cyclopentylsulfonyl-tert-butylsulfonyldiazomethane, bis (iso-amylsulfonyl) diazomethane, cyclohexylsulfonyl (2-methoxyphenyl) Sulfonyl)
Diazomethane, cyclohexylsulfonyl (3-methoxyphenylsulfonyl) diazomethane, cyclohexylsulfonyl (4-methoxyphenylsulfonyl) diazomethane, cyclopentylsulfonyl (2-methoxyphenylsulfonyl) diazomethane, cyclopentylsulfonyl (3-methoxyphenylsulfonyl) diazomethane, cyclopentylsulfonyl (4 -Methoxyphenylsulfonyl) diazomethane, cyclohexylsulfonyl (2-fluorophenylsulfonyl) diazomethane, cyclopentylsulfonyl (2-fluorophenylsulfonyl) diazomethane, cyclohexylsulfonyl (4-
Fluorophenylsulfonyl) diazomethane, cyclopentylsulfonyl (4-fluorophenylsulfonyl)
Diazomethane, cyclohexylsulfonyl (4-chlorophenylsulfonyl) diazomethane, cyclopentylsulfonyl (4-chlorophenylsulfonyl) diazomethane, cyclohexylsulfonyl (3-trifluoromethylsulfonyl) diazomethane, cyclopentylsulfonyl (3-trifluoromethylsulfonyl) diazomethane, cyclohexylsulfonyl (4 -Trifluoromethoxysulfonyl) diazomethane, cyclopentylsulfonyl (4-trifluoromethoxysulfonyl) diazomethane, cyclohexylsulfonyl (1,3,5-trimethylphenylsulfonyl) diazomethane, cyclohexylsulfonyl (2,3,4-trimethylphenylsulfonyl) diazomethane, Cyclohexylsulfonyl (1,
3,5-triethylphenylsulfonyl) diazomethane, cyclohexylsulfonyl (2,3,4-triethylphenylsulfonyl) diazomethane, cyclopentylsulfonyl (1,3,5-trimethylphenylsulfonyl) diazomethane, cyclopentylsulfonyl (2
3,4-trimethylphenylsulfonyl) diazomethane, o-toluenesulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, m-toluenesulfonyl (2,4,6-trimethylphenylsulfonyl)
Diazomethane, p-toluenesulfonyl (2,4,6-
Trimethylphenylsulfonyl) diazomethane, 2-methoxyphenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 3-methoxyphenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 4-methoxyphenylsulfonyl (2 4,6-trimethylphenylsulfonyl) diazomethane, 2-chlorophenylsulfonyl (2,4,6-
Trimethylphenylsulfonyl) diazomethane, 3-chlorophenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 4-chlorophenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 2-fluorophenylsulfonyl (2,4 6-trimethylphenylsulfonyl) diazomethane, 3-fluorophenylsulfonyl (2,4,6
-Trimethylphenylsulfonyl) diazomethane, 4-
Fluorophenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 3-trifluoromethylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 4-trifluoromethylsulfonyl (2,4,6-trimethylphenyl) Sulfonyl)
Diazomethane, 2,3-dimethylphenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 2,4-dimethylphenylsulfonyl (2,
4,6-trimethylphenylsulfonyl) diazomethane, 2,5-dimethylphenylsulfonyl (2,4,6
-Trimethylphenylsulfonyl) diazomethane, 2,
6-dimethylphenylsulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, bis (2
4,6-trimethylphenylsulfonyl) diazomethane, benzenesulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, o-toluenesulfonyl (2,3,6-trimethylphenylsulfonyl) diazomethane, p-toluenesulfonyl (2,3 , 6-Trimethylphenylsulfonyl) diazomethane, 2-methoxyphenylsulfonyl (2,3,6-trimethylphenylsulfonyl) diazomethane, 4-methoxyphenylsulfonyl (2,3,6-trimethylphenylsulfonyl) diazomethane, 4,6-dimethyl -2-hydroxymethylphenylsulfonyl (o-toluenesulfonyl)
Diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (p-toluenesulfonyl) diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (2-methoxyphenylsulfonyl)
Diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (4-methoxyphenylsulfonyl) diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (2-fluorophenylsulfonyl) diazomethane, 4,6-dimethyl- 2-hydroxymethylphenylsulfonyl (4-fluorophenylsulfonyl) diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (2,3-dimethylphenylsulfonyl) diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (2,4-
Dimethylphenylsulfonyl) diazomethane, 4,6-
Dimethyl-2-hydroxymethylphenylsulfonyl (2,5-dimethylphenylsulfonyl) diazomethane, 4,6-dimethyl-2-hydroxymethylphenylsulfonyl (2,6-dimethylphenylsulfonyl) diazomethane, phenylsulfonyl (2-naphthylsulfonyl) Diazomethane, phenylsulfonyl (1-naphthylsulfonyl) diazomethane, 4-methoxyphenylsulfonyl (2-naphthylsulfonyl) diazomethane, 4
-Methoxyphenylsulfonyl (1-naphthylsulfonyl) diazomethane, cyclohexylsulfonyl (2-naphthylsulfonyl) diazomethane, cyclohexylsulfonyl (1-naphthylsulfonyl) diazomethane, 2,
Known ones such as 4,6-trimethylphenylsulfonyl (2-naphthylsulfonyl) diazomethane and 2,4,6-trimethylphenylsulfonyl (1-naphthylsulfonyl) diazomethane are exemplified.

Among these photoacid generators, iodonium salts, sulfonium salts, and compounds having a bissulfonyldiazomethane skeleton are preferred. In particular, among bissulfonyldiazomethanes, cyclohexylsulfonyl (1,3,5-trimethylphenylsulfonyl) diazomethane, cyclohexylsulfonyl (4-methoxyphenylsulfonyl) diazomethane, cyclohexylsulfonyl (4-fluorophenylsulfonyl) diazomethane, benzenesulfonyl (2, 4,6-trimethylphenylsulfonyl) diazomethane, p-toluenesulfonyl (2,4,6-trimethylphenylsulfonyl) diazomethane, 4-methoxyphenylsulfonyl (2,4
6-trimethylphenylsulfonyl) diazomethane, bis (2,4,6-trimethylphenylsulfonyl) diazomethane, phenylsulfonyl (2-naphthylsulfonyl) diazomethane, phenylsulfonyl (1-naphthylsulfonyl) diazomethane, 4-methoxyphenylsulfonyl (2-methoxyphenylsulfonyl) Naphthylsulfonyl) diazomethane, 4-
Preferred compounds are methoxyphenylsulfonyl (1-naphthylsulfonyl) diazomethane, cyclohexylsulfonyl (2-naphthylsulfonyl) diazomethane, and cyclohexylsulfonyl (1-naphthylsulfonyl) diazomethane.

In the photosensitive resin composition of the present invention, a photoacid generator of 0.001 to 100 parts by weight of the resin of the present invention is used.
It is used in a proportion of 30 parts by weight, preferably 0.05 to 20 parts by weight. If the amount of the photoacid generator is less than this range, the sensitivity is inferior, and if the amount of the photoacid generator is more than this range, the resist pattern becomes trapezoidal due to a decrease in the transparency of the resist film due to the photoacid generator and the resolution becomes lower. May cause deterioration.

The photosensitive resin composition of the present invention may be any of dyes, pigments, coatability improvers, JP-A-7-92679, JP-A-8-15864, and JP-A-8-158 as long as the properties are not impaired. -262721, JP-A-10-20
Other additives, such as the organic carboxylic acid described in JP-A-501, may be included.

Usually, the photosensitive composition of the present invention is used by dissolving the above components in an appropriate solvent. The solvent is not particularly limited as long as it is a solvent that has sufficient solubility for the resin of the present invention, the photoacid generator, and the basic compound of the present invention and provides good coating properties. 2-hexanone, ketone solvents such as cyclohexanone, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, diethyl oxalate, ethyl pyruvate, ethyl-2-hydroxybutyrate, ethyl acetoacetate; Butyl acetate, amyl acetate, ethyl butyrate, butyl butyrate, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, methyl α-hydroxyisobutyrate, β
-Ester solvents such as methyl methoxyisobutyrate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol dimethyl ether And the like, or a mixed solvent thereof, or a solvent to which an aromatic hydrocarbon is further added. The proportion of the solvent used is
It is preferred that the weight ratio is in the range of 1 to 20 times the total amount of solids in the photosensitive resin composition.

Next, the antireflection film of the present invention will be described. The anti-reflection film used in the pattern forming method of the present invention is used to reduce reflection of light from the substrate during exposure and to reduce pattern side wall roughness and sensitivity change due to a standing wave of the resist pattern. It is. Specifically, JP-A-6-118630, JP-A-9-90
No. 615, JP-A-9-291228 and JP-A-10-3001, which are formed on a photosensitive layer or JP-A-9-201263 and JP-A-10-69072. JP-A-10-12
No. 534, JP-A-10-204328, and JP-A-10-228113, which are formed below a photosensitive layer, can be used.

More specifically, as an example of the antireflection film formed on the photosensitive layer, see, for example, JP-A-9-271.
No. 228, which contains a low-refractive index compound such as perfluoroalkylsulfonic acid or perfluoroalkylcarboxylic acid in a water-soluble resin such as polyvinylpyrrolidone or a water-soluble alkylsiloxane polymer. A film is usually formed by coating and drying as an aqueous solution.

The acidity of the antireflection film is preferably pH 4 or less, more preferably pH 3 or less. The lower limit is preferably pH 1 or higher. If the pH is larger than this range and is close to neutral, the resist pattern tends to be greatly deteriorated in shape due to the delay time from exposure to development. Also,
When the pH is lower than this range and the acidity becomes strong, the residual film ratio of the resist film tends to be deteriorated.

Next, the pattern forming method of the present invention will be described. The pattern forming method of the present invention comprises the steps of (1) forming, on a substrate, (a) a resin whose alkali solubility increases by the action of an acid, (b) a compound generating an acid upon exposure, (c) a basic compound, and (d) A) a step of applying a photosensitive resin composition containing a solvent and drying to form a photosensitive layer; and (2) forming an acidic antireflection film on the substrate at a lower portion in contact with the photosensitive layer or an upper portion of the photosensitive layer. Forming, (3) selectively exposing the photosensitive layer with far ultraviolet light, and (4) removing the exposed portion of the photosensitive layer by developing the photosensitive layer to form a pattern; It is characterized by having.

The substrate used in the present invention is a substrate usually used as a substrate for manufacturing semiconductors, such as a silicon substrate or a gallium arsenide substrate. Note that an insulating film, a conductive film, a semiconductor film, or the like may be formed on the surface of the substrate used in the present invention. The coating of the photosensitive resin composition is usually performed by spin coating using a spin coater, and then performed on a hot plate or the like usually at 60 to 130 ° C. for 30 minutes.
Drying for seconds to 5 minutes forms a photosensitive layer.

The antireflection film is formed in contact with the photosensitive layer,
It may be above or below the photosensitive layer (between the substrate and the photosensitive layer),
When formed on the lower part, after forming an anti-reflection film on the substrate, the photosensitive layer may be formed on the anti-reflection film. However, when formed on the upper part, the effect of the present invention is particularly remarkable. preferable. In particular, when an anti-reflection film made of a water-soluble resin is formed on the photosensitive layer, the removal of the anti-reflection film can be performed simultaneously with development, which leads to simplification of the pattern forming step, which is more preferable. The antireflection film is formed by applying the above resin aqueous solution by a spin coater or the like and drying the same as in the case of coating the photosensitive resin composition. Drying conditions are usually 20 ° C. to 130 ° C. for 30 seconds to 5 minutes. For exposure, 254 nm of a low-pressure mercury lamp, or 157 nm, 193 nm, or 222 nm using an excimer laser or the like as a light source.
m, 248 nm, etc., and 150-300 nm far ultraviolet light is used. Light at the time of exposure may be broad instead of monochromatic light. Exposure by a phase shift method is also applicable.

For the development of the photosensitive resin composition of the present invention, 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-
Secondary amines such as propylamine, tertiary amines such as triamineethyl, N, N-diethylmethylamine, quaternary ammonium salts such as tetramethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide, or A developer in which an alcohol, a surfactant, and the like are added to the developer can be used. The pattern forming method of the present invention is useful not only for the production of VLSI, but also for general IC production and mask production.

[0035]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the examples unless it exceeds the gist thereof.

Resin Synthesis Example 1 Synthesis of 1-ethoxyethylated poly (p-vinylphenol) Poly (p-vinylphenol) (weight average) was placed in a 1-liter four-necked flask equipped with a nitrogen inlet tube, a stirrer, and a thermometer. 80 g of molecular weight 15,000) and tetrahydrofuran 40
0 ml was added and dissolved, and ethyl vinyl ether 2 was further added.
8.8 g were added. To this, 0.4 ml of 12N hydrochloric acid was added dropwise and reacted at 40 ° C. for 1.5 hours with stirring.
After the reaction, 4 ml of 28% aqueous ammonia was added and stirred. After adding 200 ml of methanol and stirring, 7.2 l of pure water was added.
After dropping into the solution to precipitate a polymer, the polymer was separated by filtration and vacuum-dried at room temperature for 10 hours to obtain 101 g of 1-ethoxyethylated poly (p-vinylphenol).
The 1-ethoxyethylation ratio of the synthesized 1-ethoxyethylated poly (p-vinylphenol) was 35% as a result of 1H-NMR analysis. The 1-ethoxyethylation ratio is determined by comparing the proton peak (5.3 ppm) area of the methine of the 1-ethoxyethyl group with the proton peak (6.6 ppm) area of the benzene ring in the 1H-NMR spectrum. did.

Examples 1 to 6 and Comparative Examples 1 to 3 (1) Preparation of resist photosensitive solution According to the formulation shown in Table 1, the resin, photoacid generator and basic compound of Synthesis Example 1 were dissolved in a solvent. After, 0.2μm
The resist photosensitive liquids (S1) to (S9) were prepared by filtration with a membrane filter.

[0038]

[Table 1]

[0039]

[Table 2]

(2) Preparation of Coating Solution for Antireflection Film Polyvinylpyrrolidone (weight average molecular weight 3000)
1 g and 0.4 g of perfluorooctylsulfonic acid were dissolved in 19.5 g of demineralized water, and the solution was filtered through a 0.2 μm membrane filter to prepare an antireflection coating solution (T1). The acidity of the antireflection coating solution was measured to be pH 2.0.

(3) Formation and evaluation of resist pattern The resist photosensitive solution shown in Table 1 was spin-coated on a silicon substrate at 2000 to 3000 rpm, and prebaked on a hot plate at 90 ° C. for 60 seconds to form a resist film. Is 0.
A 72 μm resist-coated substrate was obtained. Then, a coating solution for antireflection film having a thickness of 0.043 μm was formed on the resist photosensitive layer.
m (however, the antireflection film was not applied in Comparative Example 4).
rF excimer laser reduction projection exposure apparatus (NA = 0.4
After exposure in 2) and baking at 110 ° C. for 60 seconds, development was carried out with a 2.38% aqueous solution of tetramethylammonium hydroxide for 60 seconds to form a pattern. The sensitivity, resolution, and pattern shape were evaluated using the resist pattern thus obtained, and the results shown in Table 2 were obtained.

Each evaluation was performed according to the following criteria. Sensitivity: Observe the resist pattern with a scanning electron microscope,
The exposure amount (appropriate exposure amount) required for resolving a 0.26 μm line and space according to a specified line width was defined as sensitivity. The lower the exposure, the higher the sensitivity. Resolution: Line resolved at the appropriate exposure above
The resolution was defined as the line width of the thinnest line and space that was resolved without reducing the thickness of the space. Remaining film ratio: Using a mask having a line and space line width of 0.26 μm, the height of a 0.26 μm line and space line obtained by exposing and developing at the above-mentioned appropriate exposure amount was measured. The value was divided by the resist coating film thickness and expressed as a percentage.

[0043]

[Table 3]

[0044]

According to the method of forming a resist pattern on a substrate using a radiation-sensitive resin composition and an acidic anti-reflection film according to the method of the present invention, the basic content of the radiation-sensitive composition is reduced. By using a compound having a pKa of 7.70 or more as a compound, it is possible to form a resist pattern having high sensitivity, high resolution, a good resist pattern shape, no side wall roughness, and a high residual film ratio. It is possible.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuki Tanaka 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Chemical Corporation Yokohama Research Laboratory F-term (reference) 2H025 AA00 AA01 AA02 AA03 AB16 AC04 AC08 AD03 BE00 BE10 BG00 CB13 CB17 CB28 CB29 CB41 CB43 CB45 CB52 CC03 CC20 DA03 DA34 EA04 EA10 FA17 5F046 AA07 CA04 CA08 JA00 LA12 PA17

Claims (4)

[Claims] 1. A substrate comprising: (1) a resin having (a) a resin whose alkali solubility is increased by the action of an acid, (b) a compound generating an acid upon exposure, (c) a basic compound, and (d) a solvent. Forming a photosensitive layer by applying and drying a photosensitive resin composition containing the same, and (2) forming an acidic antireflection film on the substrate at a lower portion in contact with the photosensitive layer or an upper portion of the photosensitive layer. (3) a step of selectively exposing the photosensitive layer with far ultraviolet rays; and (4) a step of forming a pattern by removing the exposed portion of the photosensitive layer by developing the photosensitive layer. In the method, the pKa of the basic compound is
Is 7.70 or more. 2. The pattern forming method according to claim 1, wherein said acidic antireflection film is formed on a photosensitive layer. 3. The pattern forming method according to claim 1, wherein the acidic antireflection film is formed using an aqueous solution containing a water-soluble resin and having a pH of 4 or less. 4. A resin whose alkali solubility is increased by the action of an acid, wherein the resin having a phenolic hydroxyl group and / or a carboxyl group has at least a part of a phenolic hydroxyl group and / or a carboxyl group protected by an acid labile group. The pattern forming method according to claim 1, wherein