JPH02228665A - Positive type photoresist composition and formation of resist pattern - Google Patents

Abstract

PURPOSE:To improve resolution, sensitivity and the faithfulness to mask patterns, etc., by incorporating an alkaline soluble novolak resin, quinone diazide compd. and specific solvent mixture into the above compsn. CONSTITUTION:The alkaline soluble novolak resin, the quinone diazide compd. and ketone alcohols A and B consisting of at least one kind selected from the group consisting of cyclic ketones, esters, propylene glycols, and the derivatives thereof as the specific solvent mixture are incorporated into the compsn. The solvent mixture has 80/20 to 99/1 mixing weight ratio A/B of the solvent A and the solvent B. The positive type photoresist compsn. which has no striation in the case of applying the same on a substrate and has the excellent resolution, the sensitivity and the faithfulness to the mask patterns, etc., is obtd. in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a positive photoresist composition and a method for forming a resist pattern using this positive photoresist composition, and more specifically, to a method for forming a resist pattern using the positive photoresist composition. A positive photoresist composition that also has excellent resolution, sensitivity, fidelity to mask patterns, and perpendicularity to the underlying substrate.

The present invention also relates to a resist pattern forming method suitable for forming fine patterns by lithography in the manufacture of semiconductor integrated circuit devices, for example, by using this positive photoresist composition.

[Prior Art and Problems to be Solved by the Invention] In the field of semiconductor device manufacturing, we are now in the age of mass production of INbit ORAMs, and in the future we are about to move on to mass production of 4Mbit and even 16Nbit DRAMs. Accordingly, the line width of the device pattern is also 1.0pm.
to 0.7-0.81Lm, and 16) Ibit
DRAM is finally entering the half-micron era with 0.5 gm.

As the line width of circuit patterns becomes finer, resists used for microfabrication of underlying substrates must have, for example, high pattern resolution and excellent pattern profiles (resist pattern cross sections are rectangular, etc.). etc. are required. In particular, the underlying substrate is etched using a reactive etching method (
When processing by RIE, the resist pattern is particularly required to have high resolution and an excellent pattern profile.

Under such circumstances, a positive photoresist composition consisting of an alkali-soluble novolac resin, a quinonediazide compound, and an organic solvent has been used to form a resist pattern (Japanese Patent Publication No. 37-1801).
Publication No. 5, Publication No. 37-3627, Publication No. 37-1954
No. 45-9610, etc.).

As a conventional method for forming a fine resist pattern in a semiconductor lithography process using a positive photoresist composition, for example, a positive photoresist composition is coated on a substrate such as a silicon urchin using a spinner coating method or the like. There is a method in which a photosensitive agent layer is formed by coating using an appropriate coating method and drying, and after exposure is performed using an exposure device, the exposed areas are selectively dissolved and removed using a developer.

However, there are the following problems in the process of applying a positive photoresist composition onto a substrate.

That is, when a positive photoresist composition is applied onto a substrate, the surface of the photosensitive agent layer becomes wavy or a radial striped pattern appears on the surface of the photosensitive agent layer, and the layer thickness decreases. May be uneven.

This phenomenon in which the layer thickness becomes non-uniform is called striation.

Due to the difference in layer thickness caused by this striation, the exposure energy necessary to obtain an appropriate line width is not irradiated in areas where one layer thickness is large (the line width of the turn becomes large, and conversely, the layer thickness is In small areas, the line width of the pattern becomes smaller due to excessive exposure energy being irradiated.This variation in line width causes the linearity of the pattern to be lost, resulting in poor dimensional accuracy and reproducibility in microfabrication. This poses a very serious problem in microfabrication: the inability to obtain

None of the currently used positive photoresist compositions is satisfactory with respect to striations.

Ethylene glycol monoethyl ether acetate, which is commonly used as a solvent in positive photoresist compositions, has significant toxicity and therefore poses problems in use.

Furthermore, it is not possible to appropriately select a solvent solely for the purpose of improving the striation.

This is because the solvent has a significant effect on the photoresist itself.

An object of the present invention is to provide a positive photoresist composition that does not cause the problem of striations and has excellent resolution, pattern profile, sensitivity, fidelity to a mask pattern, and perpendicularity to an underlying substrate.

Another object of the present invention is to provide a method for forming a resist pattern that allows fine processing of a base substrate with high precision using the positive photoresist composition.

[Means for Solving the Aforesaid Problem] In order to achieve the above object, the present inventors have made extensive studies and have developed a positive photoresist composition comprising an alkali-soluble novolac resin, a quinonediazide compound, and a specific mixed solvent. The present invention has been achieved by discovering that a positive photoresist composition can achieve the above object and that an excellent resist pattern can be formed using such a positive photoresist composition.

To achieve the above object, the present invention comprises a quinonediazide compound, an alkali-soluble novolac resin, (A) ketone alcohols, (B) cyclic ketones, esters,
A positive photoresist composition comprising: a mixed solvent consisting of at least one selected from the group consisting of propylene glycols and derivatives thereof; This method of forming a resist pattern is characterized in that the resist pattern is coated on a resist pattern, heat treated, irradiated with radiation through a photomask, and developed.

The present invention will be explained in detail below.

A. Positive Photoresist Composition The positive photoresist composition of the present invention contains a quinonediazide compound [component (1)] as a photosensitizer and an alkali-soluble novolak resin [component (II)].

One component (I) - component CI in the present invention) is a quinonediazide compound.

There are no particular restrictions on the quinonediazide compound, but examples include orthobenzoquinonediazide compounds,
Examples include orthonaphthoquinone diazide compounds and esters of these with compounds having free hydroxylation.

Preferred quinonediazide compounds include, for example, orthonaphthoquinonediazide compounds, such as orthonaphthoquinonediazide sulfonyl chloride, and compounds containing a free hydroxyl group, such as hydroxybenzophenone or its derivatives, gallic acid or its derivatives, acetone/pyrogallol resin, polyhydroxystyrene, and the like. Examples include esters with polymers.

Particularly preferred quinonediazide compounds include naphthoquinonediazide esters of hydroxybenzophenones.

Examples of naphthoquinone diazide esters of hydroxybenzophenones include 1,2-naphthoquinone diazide esters of 2,4,4'-) lyhydroxybenzophenone, and 1,2- of 2,3,4-) lyhydroxypenzophenones. naphthoquinone diazide ester, 2,
1 of 3,4,4°-tetrahydroxybenzophenone.
2-naphthoquinonediazide-5-sulfonic acid ester,
1,2-naphthoquinonediazide-5-sulfonic acid ester of 2,3,3',4-tetrahydroxybenzophenone, 1,2-naphthoquinonediazide ester of 2,2°,4,4°-tetrahydroxybenzophenone,
Examples include 2.2', 3,4.4'-pentahydroxybenzophe/7(7)1,2-naphthoquinonediazide-based esters.

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

When using the naphthoquinone diazide ester, the quinone diazide ester does not need to be a completely esterified product, and the average degree of esterification is 50 mol% or more, preferably 60 mol% or more and 90 mol% or less,
More preferably, it is 65 mol% or more and 85 mol% or less.

If the average degree of esterification is less than 50 mol%, the apparent sensitivity increases, but not only does the remaining film rate and resolution of unexposed areas deteriorate, but also the pattern profile becomes trapezoidal, and the pattern profile becomes trapezoidal, and the pattern profile becomes trapezoidal. This has the disadvantage of not being possible.

Further, when the average degree of esterification exceeds 90 mol%,
Not only does sensitivity and resolution deteriorate, but storage stability may also be affected.

In addition to the quinonediazide compound, the photosensitizers in this invention include 1, for example, 2 as long as they do not impede the purpose of the invention.
,3.4-)ris(6-diacy5,6-sihydro5
It may contain other photosensitizers including diazo ketone compounds such as -oxo-1-naphthalenesulfonyloxy)benzophenone.

When the other photosensitizer is contained, its content is usually 7.
It is not more than 5% by weight, especially from 10 to 60% by weight.

Component (■) - The alkali-soluble novolac resin, which is the component (■), is a base polymer in the positive photoresist composition of the present invention.

Specific examples of this alkali-soluble novolak resin include:
For example, phenol novolac resin, cresol novolac resin, etc. can be mentioned.

Among these, cresol novolac resins are preferred.

The cresol novolac resin is not particularly limited, but a mixture of 40 to 60% by weight of m-cresol, 25 to 45% by weight of P-cresol, 15% by weight of O-cresol 0N, and 10 to 25% by weight of xylenol is more preferable. is m-cresol 45-55fi amount%, p
-Cresol 30-40% by weight, O-cresol 0-5
% by weight, and xylenol 12-20! A suitable example is a condensate of a mixture of i amount % and formaldehyde.

If the ratio of each component in the mixture is out of the above range, the resulting resist pattern may not be rectangular and perpendicular to the base substrate in terms of fine pattern.

The preferred component (II) can be obtained by subjecting a mixture containing 1m-cresol, p-cresol, 0-cresol and xylenols in the above ratios to a condensation reaction with formaldehyde under an appropriate acid catalyst, and then It can be obtained by a known production method in which water, chloride, etc. are removed by heating under reduced pressure.

Examples of the acid catalysts that can be used in the production of the component (■) include oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, and P-)luenesulfonic acid.

Examples include Teuchell's reagent and acid clay.

The molecular weight of the alkali-soluble Nopolar 2 resin which is the component (n) (measured value when polystyrene is used as a standard substance in gel permulation chromatography) is 1, usually 8,000 to 20,000°, preferably s
,ooo~15. It's Goo.

If the weight average molecular weight is less than 8,000, the solubility in the developer increases, film loss in unexposed areas increases, and the cross-sectional shape of the resulting resist pattern may lose its rectangularity and become trapezoidal. . On the other hand, the above weight average molecular weight is 20. If it exceeds Goo, the sensitivity will drop significantly, the resolution will deteriorate, and the dimensional accuracy of processing the underlying substrate in the etching process will drop. Furthermore, since the influence of standing waves increases, this also reduces the dimensional accuracy of processing the underlying substrate.

~Mixed solvent- The mixed solvent used in the present invention includes ketone alcohols as the solvent (A), cyclic ketones as the solvent (B),
and at least one selected from the group consisting of esters, propylene glycols, and derivatives thereof.

Examples of the ketone alcohols as the solvent (A) include diacetone alcohol, ketobutanol, 2-
Examples include hydroxy-2-methylbutanone-2,3.4-dimethyl-4-hydroxy-hexane-2,3,4-dimethyl-4-hydroxy-pentanone-2.

These can be used alone or in combination of two or more.

Among these, preferred are diacetone alcohol,
Ketobutanol, 2-hydroxy-2-methylbutanone-2, and the like.

The cyclic ketone that is the solution W (B) includes cyclopentanone, cyclohexanone, 2-methylcyclohexanone,
Examples include cycloheptanone.

These can be used alone or in combination of two or more.

Among these, cyclopentanone and cyclohexanone are preferred.

Examples of the esters as the solvent (B) include lower alkyl acetates such as methyl acetate, ethyl acetate, butyl acetate, and isoamyl acetate, lower alkyl propionates, and the like.

These can be used alone or in combination of two or more.

Among these, preferred are ethyl acetate, butyl acetate, isoamyl acetate, and the like.

Examples of the propylene glycols (B) include propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, and propylene glycol monomethyl ether acetate.

propylene glycol monomethyl ether acetate,
Examples include propylene glycol monopropyl ether acetate.

These can be used alone or in combination of two or more.

Among these, preferred are propylene glycol monoethyl ether acetate and propylene glycol monoethyl ether acetate.

The mixed weight ratio [(A)/(B)] of solvent (A) and solvent (B) in this mixed solvent is 80/20 to 99/1.
It is preferable that it is, and it is especially preferable that it is 85/Is - 9515.

If the mixing weight ratio is out of the range, striations are likely to occur.

1. Blending ratio of each component - The blending ratio of the component (1) and the component (■) in the positive photoresist composition of the present invention is the component (n
), the amount of the quinonediazide compound as component (1) is usually 10 to 50 parts by weight, preferably 20 to 40 parts by weight.
Parts by weight.

If the blending ratio of the quinonediazide compound is less than 10 parts by weight, when used as a resist, the solubility of the exposed and non-exposed areas in the developer will be insufficient, making it impossible to obtain a pattern with excellent contrast. If the amount exceeds 50 parts by weight, the resist film may become brittle, and the pattern may be easily damaged or the resist film may be easily peeled off from the substrate. .

The blending amount of the mixed solvent is the component (r) and the component (n).
The amount is usually 40 to 95 parts by weight, particularly 5G-90 parts by weight, based on a total of too 31 parts by weight of the mixed solvent.

If the amount of the mixed solvent is less than 40 parts by weight, the viscosity becomes high, causing problems such as inconvenience during coating and precipitation.

Moreover, if the amount exceeds 95 parts by weight, it may take a long time to dry the photosensitive agent layer, which may be impractical.

-Other components- The positive photoresist composition of the present invention includes the quinone diazide compound, the alkali-soluble novolak resin, and the mixed solvent, as well as other components such as a sensitizer, a dye, a plasticizer, a stabilizer, and an adhesion promoter. It may also contain.

However, in that case, it is necessary to appropriately set the amounts of other components added so as not to impede the object of the present invention.

The sensitizer can be selected depending on the type of radiation used when forming the photoresist. For example, if visible light is used as the radiation, Vireso, 2H-pyrido[3,2-bl-1 ,4-oxazine-3[4H]
ons, 10B-pyrido[3,2-bl [1,4]-
Benzothiazines, uranols, l-hydroxybenzotriazoles, hydantoins, barbyls,
Glycine anhydride, alloxanes, maleimides, etc. can be used.

Examples of the dye include oil-soluble dyes, disperse dyes,
Basic dyes, methine dyes, stilbenes, 4,4-diaminostilbenesulfonic acid derivatives.

Examples include fluorescent brighteners such as coumarin derivatives and pyrazoline derivatives, and azo dyes.

Examples of the plasticizer include stearic acid, acetal resin, alkyd resin, and phenoxy resin. Examples of the stabilizer include phenols such as paramethoxyphenol and paramethoxy[-butylphenol. can be mentioned.

Examples of the adhesion promoter include silico compounds such as 3-7 minobrobyltriethoxysilane, hexamethyldisilazane, chloromethylsilane, and trimethoxysilane.

The positive photoresist composition of the present invention is obtained by blending the above-mentioned components.

B. Formation of a resist pattern - To form a resist pattern of the present invention, 1. Usually, first, the positive photoresist composition is applied onto a base substrate.

Examples of the base substrate include silicone wafers and the like.

The coating liquid can be applied to the base substrate by a spinner coating method, a bar coater method, or the like.

After applying the positive photoresist composition, the solvent is removed by drying or the like, thereby forming a photosensitive agent layer on the surface of the underlying substrate.

Next, the photosensitive agent layer is exposed to radiation by irradiating it with radiation through a predetermined photomask using a reduction type projection exposure device or the like.

Examples of the radiation include visible light, ultraviolet rays, far infrared rays, X-rays, γ-rays, electron beams, and molecular beams.

Examples include synchrotron radiation and proton beams.

Thereafter, by performing development using an appropriate developer, the portions made solubilized by exposure are selectively dissolved and removed, making it possible to obtain a resist pattern faithful to the mask pattern.

Examples of the developer include quaternary ammonium hydroxide such as tetramethylammonium hydroxide;
Aqueous solutions of alkali metals such as sodium hydroxide and potassium hydroxide, as well as developing solutions prepared by adding alcohol, surfactants, etc. to these solutions, depending on the purpose, can be suitably used.

Among these, an aqueous solution of tetramethylammonium hydroxide is particularly preferred.

When the positive photoresist composition of the present invention is applied to a substrate, it not only does not produce striations but also achieves extremely high resolution, which is difficult to achieve with conventional single-layer resists. A resist pattern having good perpendicularity to the underlying substrate and an excellent profile is formed in the fine pattern.

Therefore, the obtained resist pattern is suitable as a resist pattern for microfabrication of a base substrate, and can be suitably used, for example, in fields such as the manufacture of semiconductor integrated circuit elements such as VLSI and IC, or the manufacture of photomasks. It is also useful in the field of offset printing.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention. Note that the present invention is not limited to these Examples, and in the following Examples and Comparative Examples, "1%" means "% by weight" unless otherwise specified.

(Example 1) 2.3, 4. -) 1. of lyhydroxybenzophenone.
2-naphthoquinonediazide-5-sulfonic acid ester (
(average degree of esterification 75 mol%) [sensitizer] and cresol novolac resin [m-cresol 48.4%, p-cresol 36.9%, 0-cresol 0.4%, 2
．． Manufactured from a mixture of 2.0% 6-xylenol and 12.6% mixture of 2,4-xylenol and 2,5-xylenol and formaldehyde, molecular weight 10.50
01 and (sensitizer): (alkali-soluble cresol novolak resin) in a weight ratio of 20:80, and a solid content of 102% by weight of cyclopentanone to 90% by weight of diacetone alcohol. The solid content is 38% by weight with respect to 62% by weight of the solvent.
A positive photoresist composition was prepared by mixing the components in proportions of % by weight.

Next, the obtained solution was filtered through a Teflon membrane filter (0.2 gm), and coated using a spin coater for 40 minutes.
After spin coating on inch silicon wafer, temperature 1
Heat treatment was performed on a hot plate at 05° C. for 2 minutes to form a resist film.

When the thickness of the obtained resist film was measured using an optical film thickness meter, it was found to be a uniform film with a film thickness of 2.07 zm.

After that, a reduction projection exposure device! (NSR-1505G
, using a wafer stepper, NA-0,3(1),
Exposure was performed by irradiating 436 mm light through a test reticle.

Add this to 2.3% tetramethylammonium hydroxide.
After developing for 1 minute using an 8% aqueous solution, a resist pattern was formed by rinsing for 1 minute with ion-exchanged water.

The cross-sectional shape of the obtained resist pattern was examined using a scanning microscope 1.
11 (SEX), the resist pattern was perpendicular to the base substrate, and a good pattern profile with excellent rectangularity was realized.

Also, when we investigated the resolution of the resist, we found that it was 0.85 μm.
The line-and-space pattern was well resolved, and the fidelity to the mask pattern was also good up to 0.90 #Lm.

Further, when the resist pattern obtained in this example was observed from above the pattern at a low acceleration voltage using a scanning electron microscope, no resist residue (scum) was detected.

(Example 2) The same procedure as in Example 1 was carried out, except that the solvent was 67% by weight and the solid content was 33% by weight.

The formed resist film was a uniform film with a thickness of 1.2 JL m. When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.754m
The fidelity to the 5 mask pattern was good up to 0.8 pm.Furthermore, when scum was observed in the same manner as in Example 1, no scum was detected.

(Example 3) The same procedure as in Example 1 was carried out except that a mixed solvent consisting of 80% by weight of diacetone alcohol and 20% by weight of cyclopentanone was used as the solvent.

The formed resist film was a uniform film with a thickness of 2.0 pm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0. f15
It resolved lines and spaces of 1 Lm, and the fidelity to the mask pattern was good up to 0.9 Bm.

Furthermore, when the scum was observed in the same manner as in the example work, no scum was detected.

(Example 4) The same procedure as in Example 1 was carried out except that a mixed solvent consisting of 95% by weight of diacetone alcohol and 5% by weight of amyl acetate was used as the solvent.

The formed resist film was a uniform film with a thickness of 2.0 pm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.85p
It resolved lines and spaces of m, and the fidelity to the mask pattern was good up to 0.9 m. Rough scum was also observed in the same manner as in Example 1, and was not detected. .

(Example 5) The same procedure as in Example 1 was carried out except that a mixed solvent consisting of 90% by weight of diacetone alcohol and 10% by weight of propylene glycol methyl ether acetate was used as the solvent. .

The formed resist film was a uniform film with a thickness of 2.0 g and m.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resulting resist pattern had a line and space resolution of 0.85 μm, and the fidelity to the mask pattern was good up to 0.9 μm.

When the particles and scum were also observed in the same manner as in Example 1, they were not detected.

(Example 6) In Example 1, diacet 77/I was used as the solvent.
Example 1 was carried out in the same manner as in Example 1, except that a mixed solvent consisting of 1% by weight of J/Cole 80, 10% by weight of propylene glycol monomethyl ether acetate, and 10% by weight of cyclopentanone was used.

The formed resist film was a uniform film with a thickness of 2.0 JLm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.85gm
lines and spaces were resolved, and the fidelity to the mask pattern was good up to 0.91 Lm.Furthermore, when scum was observed in the same manner as in Example 1, no scum was detected.

(Example 7) In Example 1, ketobutanol 8 was used as the solvent.
The same procedure as in Example 1 was carried out except that a mixed solvent consisting of 0% by weight and 20% by weight of cyclopentanone was used.

The formed resist film was a uniform film with a thickness of 2.01 tm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.85JL
m lines and spaces were resolved, and the fidelity to the mask pattern was good up to 0.9 gm.Furthermore, when scum was observed in the same manner as in Example 1, it was not detected.

(Example 8) In Example 1, 2-hydroxy-
The same procedure as in Example 1 was carried out, except that a mixed solvent consisting of 290% by weight of 2-methyl-butanone and 10% by weight of cyclopentanone was used.

The formed resist film has a thickness of 2. It was a uniform film of OILm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern was 0.85 gm line and space, and the fidelity to the mask pattern was good up to 0.9 pm. - Rough scum was also the same as in Example 1 above. When observed, it was not detected.

(Example 9) In Example 1, 1,2-naphthoquinone of 2,3,4-tri-droxybenzophenone was used as the photosensitizer.
5-sulfonic acid ester (average degree of esterification 75 mol%) and 1,2-naphthoquinone-5-sulfonic acid ester of 2.3,4.4'-tetrahydroxybenzophenone (average degree of esterification 75 mol%) and 50% by weight: 50
A positive photoresist composition was prepared in the same manner as in Example 1 except that 67% by weight of the solvent and 37% by weight of the solid content were mixed.
A resist film was prepared and a resist pattern was formed in the same manner as described above.

The formed resist film was a uniform film with a thickness of 2.0 gm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.75 m
lines and spaces were resolved, and the fidelity to the mask pattern was good up to 0.81 Lm.Furthermore, when scum was observed in the same manner as in Example 1, no scum was detected.

(Example 10) In Example 7, 1,2-naphthoquinone-5-sulfonic acid ester of 2,3,4-)trihydroxybenzophenone was replaced with 1.2 of 2,4,4°-trihydroxybenzophenone. -Other than using naphthoquinone-5-sulfonic acid ester (average degree of esterification 75 mol%),
A positive photoresist composition was prepared in the same manner as in Example 1, and a resist film and a resist pattern were formed in the same manner as in Example 1.

The formed resist film was a uniform film with a thickness of 1.21 Lm.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example '1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern is 0.75g
It resolved lines and spaces of m, and the fidelity to the mask pattern was good up to 0.8 pm.

Rough scum was also tested in the same manner as in Example 1, but no detection was found.

(Example it) In Example 8, a reduction projection exposure apparatus (N S
R-1505G, wafer stepper, NA-0°3
Example 7 was carried out in the same manner as in Example 7, except that a reduction type projection exposure apparatus (NSR-1505G4D, wafer stepper, NA-0,45) with even better resolution was used in place of 0). carried out.

The formed resist film was a uniform film with a thickness of 0JLrn.

When the cross-sectional shape of the resist pattern was observed in the same manner as in Example 1, it was found to be a rectangular pattern with good verticality.

The resolution of the obtained resist pattern was 0.5 Bm line and space, and the fidelity to the mask pattern was good up to 0.557 zm.

Regarding scum, when it was observed in the same manner as in Example 1, no scum was detected.

(Comparative Example 1) The same procedure as in Example 1 was carried out except that ethylene glycol monoethyl ether acetate was used as the solvent in Example 1.

The formed resist film has an average thickness of 2. Although it was OJLm, the thickness was non-uniform.

The resolution of the obtained resist pattern is 0.854m
It was resolving lines and spaces.

The resist pattern had poor verticality and rectangularity. Scum was observed in the same manner as in Example 1, but no scum was detected.

(Comparative Example 2) The same procedure as in Example 1 was carried out except that propylene glycol monomethyl ether acetate was used as the solvent in Example 1.

The formed resist film had an average thickness of 2.0 g.m, but the thickness was non-uniform.

The resolution of the obtained resist pattern is 0.85pm
It was resolving lines and spaces.

The cross-sectional shape of the pattern had rounded corners and a rectangular pattern could not be obtained.

Regarding scum, 1. When observed in the same manner as in Example 1, no scum was detected.

(Comparative Example 3) Diacetone alcohol 60 was used as the solvent in Example 1.
The same procedure as in Example 6 was carried out except that the amount of cyclopentanone was changed to 40% by weight.

The formed resist film had an average thickness of 1.2 pm, but the thickness was non-uniform.

The resolution of the obtained resist pattern was 0.8 tom line and space, but the cross-sectional shape of the pattern had rounded corners and a rectangular pattern could not be obtained.

Regarding scum, when it was observed in the same manner as in Example 1, no scum was detected.

[Effects of the Invention] According to the present invention, there is provided a positive photoresist composition that is free from striae and has excellent resolution, pattern profile, sensitivity, fidelity to a mask pattern, and perpendicularity to a base substrate when applied to a substrate; By using this positive photoresist composition, it is possible to provide a resist pattern forming method suitable for forming fine patterns by lithography, for example, in the manufacture of semiconductor integrated circuit devices.

Procedural amendment l Description of the case 1999 Patent Application No. 50724 2 Name of JA Akira Positive photoresist composition and resist pattern formation method 3 Person making the amendment Relationship with the case Patent applicant address Kita, Osaka City, Osaka Prefecture 3-6-32 Nakanoshima, Ward Name (207) Chisso Corporation Representative Sadao Nogi 6 Number of claims increased by amendment 07 Subject of amendment ``Scope of Claims'' column of the specification and ``Detailed Description of the Invention'' ” Column 8 Contents of amendment (1) The “Claims” stated on pages 1 to 2 of the specification are amended as shown in the attached sheet.

(2) "Scanning microscope (SEW) J" written on page 23, lines 1B to 17 of the specification shall be corrected to "Scanning electron microscope (SEX) J."

Attachment: The "Claims" of the specification are amended as follows.

(1) A quinonediazide compound, an alkali-soluble novolak resin, and (A) a ketone alcohol.

(B) A positive photoresist composition characterized by containing a mixed solvent consisting of at least one selected from the group consisting of cyclic ketones, esters, propylene glycols, and derivatives thereof.

(2) The positive photoresist according to claim 1, wherein the mixed solvent has a mixed weight ratio (A)/(B) of solvent (A) and solvent (B) of 80/20 to 99/1. Composition.

Claims (2)

[Claims] (1) a quinone diazide compound, an alkali-soluble novolac resin, (A) ketone alcohols, and (B) at least one member selected from the group consisting of cyclic ketones, esters, propylene glycols, and derivatives thereof. A positive photoresist composition comprising a mixed solvent. (2) The positive photoresist according to claim 1, wherein the mixed solvent has a mixed weight ratio (A)/(B) of solvent (A) and solvent (B) of 80/20 to 99/1. Composition. (2) The positive photoresist composition according to claim (1) or (2) is applied to a substrate, then heat treated, irradiated with radiation through a photomask, and developed. A method for forming a resist pattern.