JPS632044A - Positive type radiation sensitive resin composition - Google Patents

Abstract

PURPOSE:To enhance sensitivity, to improve developability, and to enable resolution of a <=1mum resist pattern by using a specified novolak resin obtained by condensing mixed cresols containing m-cresol and p-cresol with a carbonyl compound as an alkali-soluble novolak resin. CONSTITUTION:The desired resin composition is composed of 1,2-quinonediazide compound and the alkali-soluble novolak resin obtained by condensing the mixed cresols containing 30-70mol% m-cresol and 70-30mol% p-cresol with the carbonyl compound. This novolak resin has a/b=0.4-1.5 and c/b=0.4-2, where each of a, b, and c is the maximum height in the molecular weight range of 6,300-25,000, 2,500-6,000, and 150-900, respectively, and these molecular weights are those calculated in terms of polystyrene obtained by the gel permeation chromatography method using the monodispersion polystyrene as the standard.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a positive radiation-sensitive resin composition, and more specifically, a specific alkali-soluble novolak resin and a 1.2-
Ultraviolet rays, far ultraviolet rays, and X consisting of quinonediazide compounds
The present invention relates to a positive radiation-sensitive resin composition that is particularly suitable as a resist for producing highly integrated circuits that are notorious for radiation such as radiation, electron beams, molecular beams, γ-rays, synchrotron radiation, and proton beams.

(Prior Art) Conventionally, as resists for producing integrated circuits, there have been known negative resists in which a bisazide compound is blended with cyclized rubber, and positive resists in which a 1,2-quinonediazide compound is blended in an alkali-soluble resin. . In negative resists, when exposed to ultraviolet rays, the bisazide compound desorbs nitrogen and becomes nitrene, which three-dimensionally crosslinks the cyclized rubber. Therefore, the solubility of the ultraviolet irradiated areas and non-irradiated areas in a developing solution consisting of a cyclized rubber solvent is important. However, even though cross-linking does not mean that the UV irradiated area is completely cured (for this reason, negative-tone resists have a tendency to cause the resist pattern to swell in the developer). The disadvantage is that the resist pattern is large and the resolution of the resist pattern is poor.

On the other hand, positive resists contain an alkali-insoluble 1,2-quinonediazide compound in an alkali-soluble resin, so they are difficult to dissolve in a developer consisting of an alkaline aqueous solution.
It does not swell at all. In other words, in a positive resist, the 1°2-quinonediazide compound in the ultraviolet irradiated area changes to indene carboxylic acid, and even if it is developed with a developer consisting of an alkaline aqueous solution, there is extremely little change in the unirradiated area that becomes the resist pattern. A resist pattern that is faithful to the mask pattern and has high resolution can be obtained. Therefore, in recent years, when integrated circuits are required to be highly integrated, positive resists with excellent resolution are often used. It is strongly requested. For example, in the ultraviolet exposure method, a thin film of positive resist coated on a wafer is exposed to light through a mask to form a latent image, which is then developed with an alkaline aqueous solution. Unless the resist pattern is developed quickly, it will be difficult to obtain a resist pattern that is faithful to the mask.

In addition, with conventional positive resists, when trying to obtain a narrow resist pattern with a resist pattern interval (hereinafter referred to as "line width") of 1 μm or less, the exposed areas may not be completely developed and resist may remain, or the resist may become scum. A problem arises in that it adheres as a residue on the substrate. Furthermore, when a fine resist pattern is formed by increasing the exposure amount, the dimensions of the larger pattern tend to become smaller than the designed dimensions.

Furthermore, conventional positive resists have a problem in that the dimensions of the resist pattern become wider closer to the substrate due to the lower contrast.

Furthermore, with conventional positive resists, the dimensions of the resist pattern change greatly due to a slight change in the exposure dose, and when exposed with a reduction projection exposure system used in integrated circuit fabrication, a slight change in focus causes the resist pattern to change significantly. There is a problem in that the dimensions and cross-sectional shape of the pattern vary greatly.

Furthermore, when the reduction projection exposure method is used, there is a problem that the throughput is lower than when the conventional mask contact method is used, that is, the exposure time per wafer is longer.

Furthermore, when a resist pattern is transferred to a substrate in a dry etching process, the resist is consumed and the dimensions of the resist pattern vary widely, resulting in inaccurate transfer, and the wafer is heated during dry etching, causing the resist The pattern may be thermally deformed, resulting in the problem that efficient dry etching cannot be performed.

In addition, with conventional positive resists, there may be problems with the adhesion between the substrate and the resist, and in this case, when wet etching is performed, the etching solution seeps between the substrate and the resist, resulting in horizontal The problem is that the etching becomes even larger.

(Problems to be Solved by the Invention) An object of the present invention is to solve the problems of the prior art described above, and to provide a resist pattern with high sensitivity and good developability, capable of resolving a resist pattern with a line width of 1 μm or less. Another object of the present invention is to provide a positive-working radiation-sensitive resin composition that has good dry etching resistance, wet etching resistance, and heat resistance and is suitable as a positive resist for producing highly integrated circuits.

(Means for Solving the Problems) The present invention provides a positive radiation-sensitive resin composition comprising an alkali-soluble novolak resin and a 152-quinonediazide compound, in which 30 to 70 mol% of m-cresol is used as the alkali-soluble novolak resin. It is obtained by condensing a mixed cresol containing 70 to 30 mol% of p-cresol with a carbonyl compound, and has a polystyrene equivalent molecular weight determined by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. 6
300-25000.2500-6000 and 150
Alkali-soluble novolak in each range of a/b = 0°4-1.5 and c/b = 0.4-2, where the maximum heights in each range of ~900 are a, b, and C, respectively. The present invention provides a positive radiation-sensitive resin composition characterized by using a resin.

In the composition of the present invention, a novolak resin obtained by condensing a mixed cresol containing m-cresol and p-cresol with a carbonyl compound is used as the alkali-soluble novolak resin.

Usage ratio of m-cresol and p-cresol (mol%
) is 30-70/70-30. Preferably 40-60
/60 to 40.

When the proportion of m-cresol used exceeds 70 mol%, resolution and developability deteriorate. Also, the usage rate is 3
When the amount is less than 0 mol %, sensitivity, resolution and developability deteriorate. Note that this usage ratio is the usage ratio of raw materials during novolac resin synthesis.

In addition, the alkali-soluble novolak resin used in the present invention is a GPC column manufactured by Toyo Soda (G2000H, 2 columns,
G3000H, 1 bottle, G4000H, 1 bottle), the elution solvent was tetrahydrofuran, and the solvent flow rate was 1.5 ml.
/min, column temperature of 40°C, polystyrene equivalent intermolecularity determined by GPC method using monodisperse polystyrene as standard: 6300-25,000.2500-60
When the maximum height values in each range of 00 and 150 to 900 are aSb and C, respectively, a/b
= 0.4-1.5 and C/b = 0.4-2,
Preferably a/b = 0.6-1.4 and c/
It is a novolac resin in each range of b = 0.5 to 1.5. By using this alkali-soluble novolak resin, it is possible to obtain a product that is superior in resolution, sensitivity, developability, heat resistance, dry etching resistance, and wet etching resistance compared to conventional alkali-soluble novolac resins.

If the a/b value is less than 0.4 or more than 1.5, and if the c/b value is less than 0.4 or more than 2, it is difficult to resolve resist patterns of 1 μm or less. Become.

The alkali-soluble novolak resin used in the present invention is synthesized by condensing the mixed cresol with a carbonyl compound in the presence of an acid catalyst.

The carbonyl compound used in the present invention is, for example, the following -
It is represented by the general formula (1).

C=0...(1) [In the formula, R1 and R2 are the same or different and mean a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, or an aralkyl group].

In addition, as the alkyl group of R2 and R2 in the above-mentioned general formula (1), for example, methyl group, ethyl group, propyl group, butyl group, etc., and as the aryl group, for example, phenyl group, tolyl group, cumenyl group, etc. Examples of the alkenyl group include a vinyl group, propenyl group, allyl group, and butenyl group, and examples of the aralkyl group include a benzyl group, phenethyl group, and cumyl group.

Examples of the carbonyl compound include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, tolylbenzaldehyde, mesitylbenzaldehyde, phenethylbenzaldehyde, O-hydroxybenzaldehyde, m -Hydroxybenzaldehyde, p-hydroxybenzaldehyde, 0
-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, 0-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, O-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde,
Examples include p-ethylbenzaldehyde, p-n-butylbenzaldehyde, acrolein, crotonaldehyde, cinnamaldehyde, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl phenyl ketone, methyl benzyl ketone, etc. Among these compounds, formaldehyde , acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, acrolein, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl phenyl ketone/methyl benzyl ketone and the like are preferred.

Carbonyl compounds can be used alone or in combination of two or more.

The amount of the carbonyl compound used is preferably 0.7 to 3 mol, particularly preferably 0.7 to 2 mol, per mol of mixed cresol.

Examples of acid catalysts include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid;
Examples include organic acids such as formic acid, oxalic acid, and acetic acid. The amount of acid catalyst used is lXl0-' to 5 per mole of mixed cresol.
X10-' moles are preferred.

In the condensation reaction, water is usually used as the reaction medium, but a hydrophilic solvent can also be used. On this occasion,
Examples of the hydrophilic solvent used include alcohols such as methanol, ethanol, propatool, and butanol, and cyclic ethers such as tetrahydrofuran and dioxane.

The amount of these reaction media used is 20 to 100 parts by weight per 100 parts by weight of the mixed cresol and carbonyl compound.
0 parts by weight is preferred.

The reaction temperature of the condensation reaction can be adjusted as appropriate depending on the reactivity of the mixed cresol and the carbonyl compound, but is usually 10 to 200°C, preferably 70 to 150°C. Further, examples of the reaction method for obtaining the alkali-soluble novolac resin include a method in which cresol is added to a carbonyl compound and an acid catalyst as the reaction progresses. In this method of adding cresol as the reaction progresses, in order to produce the alkali-soluble novolak resin stably with better reproducibility, the total amount of p-cresol, a part of m-cresol, a carbonyl compound, and an acid are added. It is preferable to use a method in which a catalyst is charged and polymerized, and then the remaining m-cresol is added as the reaction progresses. After the condensation reaction is completed, in order to remove unreacted substances, acid catalyst and reaction medium present in the system, the internal temperature is generally raised to 130 to 230°C, and volatile components are distilled off under reduced pressure. Next, the molten alkali-soluble novolac resin is cast onto a steel belt or the like to recover the alkali-soluble novolac resin, but after distilling off the volatile matter, it is cooled and recovered by dissolving it in a solvent. You can also do it.

The 1,2-quinonediazide compound used in the present invention is
Although not particularly limited, examples thereof include 1.2-benzoquinonediazide-4-sulfonic acid ester, 1.2-naphthoquinonediazide-4-sulfonic acid ester, and 1.2-naphthoquinonediazide-5-sulfonic acid ester. Specifically, p-cresol-1,2-benzoquinonediazide-4-sulfonic acid ester, resorcinol-1
゜2-naphthoquinonediazide-4-sulfonic acid ester, pyrogallol-1,2-naphthoquinonediazide-5-
1.2-quinonediazide sulfonic acid ester IQ of (poly)hydroxybenzene such as sulfonic acid ester; 2.
4-dihydroxyphenyl-propyl ketone-1,2-
benzoquinonediazide-4-sulfonic acid ester, 2.
4-dihydroxyphenyl-n-hexylketone-1,
2-naphthoquinonediazide-4-sulfonic acid ester,
2.4-dihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2.3.4
-) lyhydroxyphenone-n-hexylketone-1,
2-naphthoquinonediazide-4-sulfonic acid ester,
2.3.4-1-lyhydroxybenzophenone-1,2-
naphthoquinonediazide-4-sulfonic acid ester, 2,
3.4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,4゜6-trihydroxybenzophenone-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2.4. 6-
) Dihydroxybenzophenone-1゜2-naphthoquinonediazide-5-sulfonic acid ester, 2.2', 4.4
'-Tetrahydroxybenzophenone-1,2-naphthoquinone diazido 5-sulfonic acid ester, 2,3.4
．． 4”-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2゜2
', 4.4'-tetrahydroxybenzophenone-1,
2-naphthoquinonediazide-4-sulfonic acid ester,
2.3,4.4'-Tetrahydroxybenzophenone-
1,2-naphthoquinonediazide-4-sulfonic acid ester, 2.2", 5゜6'-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2.2'3,4.6" -Pentahydroxybenzophenone-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2.2", 3,4.6'-Pentahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2', 3,4.5.6'
-Pentahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,3.3'
, 4.4".

5'-hexahydroxybenzophenone-1,2-nafdoquinonediazide-4-sulfonic acid ester, 2,3.
3", 4.4", 5'-hexahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2. 3', 4゜4', 5', 6-hexahytroxybenzophenone-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2.3', 4.4',
5',6-hexahydroxybenzophenone-1,2-
Naphthoquinonediazide-5-sulfonic acid ester, 2'
, 3.3', 4.4', 1, of (poly)hydroxyphenylalkyl ketone or (poly)hydroxyphenylaryl ketone such as 5-hexahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester 2-quinonediazide sulfonic acid esters, bis(p-hydroxyphenyl)methane-1,2-naphthoquinonediazide-4-sulfonic acid ester, bis(2,4
-dihydroxyphenyl)methane-1,2-naphthoquinonediazide-5-sulfonic acid ester, bis(2,3,
4-)dihydroxyphenyl)methane-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,2-bis(p-hydroxyphenyl)propane-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2.2 −
Bis(2゜4-dihydroxyphenyl)propane-1,
2-naphthoquinonediazide-5-sulfonic acid ester,
2.2-bis(2,3,4-)dihydroxyphenyl)
Bis such as propane-1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,2-quinonediazide sulfonic acid ester of (poly)hydroxyphenylcoalkane, lauryl-1,2-3,5-dihydroxybenzoate
naphthoquinonediazide-4-sulfonic acid ester, 2,
3.4-Trihydroxybenzoic acid phenyl-1,2-naphthoquinonediazide-5-sulfonic acid ester, 3゜4
．． 5-) Propyl hydroxybenzoate-1°2-naphthoquinonediazide-5-sulfonic acid ester, 3.4.
5-) (Poly) such as phenyl-1,2-naphthoquinonediazide-5-sulfonic acid ester of hydroxybenzoate
1,2-quinonediazide sulfonic acid esters of hydroxybenzoic acid alkyl ester or (poly)hydroxybenzoic acid aryl ester, bis(2,5-dihydroxybenzoyl)methane-1,2-naphthoquinonediazide-4-sulfonic ester, bis (2゜3.4-)dihydroxybenzoyl)methane-1゜2-naphthoquinonediazide-5-sulfonic acid ester, his(2,4,6
-trihydroxybenzoyl)methane-1,2-naphthoquinonediazide-5-sulfonic acid ester, p-bis(
2,5-dihydroxybenzoyl)benzene-1,2-
Naphthoquinonediazide-4-sulfonic acid ester, p-
Bis(2,3,4-1-dihydroxybenzoyl)benzene-1,2-naphthoquinonediazide-5-sulfonic acid ester, p-bis(2,4,6-trihydroxybenzoyl)benzene-1,2-naphthoquinonediazide -5
-Bis[(poly)hydroxybenzoylcoalkanes such as sulfonic acid esters or 1,2-quinonediazide sulfonic acid esters of bis[(poly)hydroxybenzoyl]benzene, ethylene glycol di(3,5-dihydroxybenzony))- 1,2-naphthoquinonediazide-5-sulfonic acid ester polyethylene glycol di(3,4,5-)lihydroxypenzoate)-1
, 2-naphthoquinonediazide-5-sulfonic acid ester, and 1,2-quinonediazide sulfonic acid esters of (poly)ethylene glycol di((poly)hydroxybenzoate).

These 1,2-quinonediazide compounds may be used alone or in combination of two or more.

The amount of these 1,2-quinonediazide compounds is usually 5 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the alkali-soluble novolak resin. If this amount is less than 5 parts by weight, 1.
Patterning is difficult because the amount of indenecarboxylic acid produced when the 2-quinonediazide compound absorbs radiation is small.On the other hand, if the amount exceeds 100 parts by weight, short-term radiation irradiation will cause damage to the irradiated area. All of the 2-quinonediazide compound cannot be decomposed, making development with a developer consisting of an alkaline aqueous solution difficult.

A sensitizer can be added to the composition of the present invention in order to improve the sensitivity as a resist.

Examples of these sensitizers include 2H-pyrido (3,2
-b) -1,4-fanxazin-3[4H]ones, 10
Examples include H-pyrido(3,2-b) (1゜4)-benzothiazines, urazoles, hydantoins, barbylic acids, glycine anhydrides, 1-hydroxybenzotriazoles, alloxanes, maleimides, etc. can.

The amount of the sensitizer to be blended is usually 100 parts by weight or less, preferably 4 to 60 parts by weight, based on 100 parts by weight of the 1,2-quinonediazide compound.

Furthermore, a surfactant or the like may be added to the composition of the present invention in order to improve the coating properties, such as streaking and the developability of the radiation irradiated area after dry coating film formation. Examples of surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkyl phenols such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; Ethers, polyethylene glycol dilaurate,
Nonionic surfactants such as polyethylene glycol dialkyl ethers such as polyethylene glycol distearate, EFTOP EF301, EF303, EF
352 (manufactured by Shin-Akita Kasei Co., Ltd.), Megafac F1
71, F173 (manufactured by Dainippon Ink Co., Ltd.), Florado FC430, FC,431 (manufactured by 3M Co., Ltd.), Asahi Guard AG710. Surflon S-382,
5CIOI 5C102, 5C103, 5C104, 5
Fluorine surfactants such as C105, 5C106 (manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341
(manufactured by Shin-Etsu Chemical Co., Ltd.), acrylic acid-based or methacrylic acid-based (co)polymer Polyflow 75, 95 (
(manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), etc.

The blending amount of these surfactants is usually 2 parts by weight or less, preferably 1 part by weight or less, per 100 parts by weight of the total amount of the alkali-soluble novolac resin and 1゜2-quinonediazide compound in the composition of the present invention. .

The composition of the present invention also contains a coloring agent to visualize the latent image of the radiation-exposed area and to reduce the effect of halation during radiation irradiation, and an adhesion aid to improve adhesiveness. It can also be blended.

Furthermore, the composition of the present invention may optionally contain a storage stabilizer,
Antifoaming agents and the like can also be blended.

The composition of the present invention is prepared by dissolving the alkali-soluble novolac resin, the 1,2-quinonediazide compound, and various ingredients in a suitable solvent in a predetermined amount, and then preparing the composition by dissolving the alkali-soluble novolac resin, the 1,2-quinonediazide compound, and various ingredients in a suitable solvent, and preparing the composition by dissolving the alkali-soluble novolak resin, the 1,2-quinonediazide compound, and various ingredients in a suitable solvent.
It is prepared by filtering through a filter of about 2 μm, and applied to a silicon wafer or the like by spin coating, flow coating, roll coating, or the like. Suitable solvents used in this case include glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate, methyl 2-oxypropionate, and 2-oxypropionate. Examples include monooxymonocarboxylic acid esters such as ethyl propionate, ketones such as methyl ethyl ketone and cyclohexane, and esters such as ethyl acetate and butyl acetate.

These solvents may be used alone or in combination of two or more. In addition, if necessary, ethers such as benzyl ethyl ether and dihexyl ether, glycol ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether, ketones such as acetonyl acetone and isophorone, and fatty acids such as caproic acid and caprylic acid. , 1-octatool, 1-nonanol,
Alcohols such as benzyl alcohol, benzyl acetate,
Addition of high boiling point solvents such as esters such as ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenyl cellosolve acetate, etc., or aromatic hydrocarbons such as toluene and xylene. Can be done.

Examples of the developer for the composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, and primary amines such as ethylamine and n-propylamine. secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, dimethylethanolamine,
Alcohol amines such as triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, or pyrrole, piperidine, 1,8-diazabicyclo(5,
4,0)-7-undecene, 1,5-diazabicyclo(
An alkaline aqueous solution in which a cyclic amine such as 4,3,0)-5-nonane is dissolved is used.

Further, the developer may contain a water-soluble organic solvent, such as methanol,
An alkaline aqueous solution containing an appropriate amount of an alcohol such as ethanol or a surfactant can also be used as the developer.

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples in any way.

(Example 1) 162 g (1.5 mol) of m-cresol, 468 g (6 mol) of p-cresol, 37% by weight were placed in a 51-triple separable flask equipped with a stirrer, a cooling tube, and a thermometer.
770 g of formaldehyde aqueous solution and 0.45 g of oxalic acid
and soak the separable flask in an oil bath to bring the internal temperature to 1.
The reaction was carried out for 1 hour while maintaining the temperature at 00°C. Then further m
As the reaction progressed, 270 g (2.5 moles) of -cresol was continuously charged into a separable flask and reacted for 2 hours.

Next, the oil bath temperature was raised to 170'C, and at the same time the pressure inside the separable flask was reduced to remove water, unreacted m-cresol, p-cresol, formaldehyde, and oxalic acid, and the molten novolac resin was returned to room temperature. It was collected.

The novolak resin was dissolved in tetrahydrofuran, and the molecular weight distribution of the novolak resin was measured using the GPC method described above. The results are shown in Table-1.

100 parts by weight of the novolak resin thus obtained and 27 parts by weight of the 1,2-quinonediazide compound listed in Table 1 were dissolved in 360 parts by weight of ethyl cellosolve acetate, and a solution of the composition of the present invention was prepared. was prepared. This composition solution was filtered through a membrane filter with a pore size of 0.2 μm.

This solution was spin-coated onto a silicon wafer using a spinner, and then prebaked on a hot plate at 90° C. for 2 minutes to form a 1.2 μm thick resist layer. Next, a GCA 4800D equipped with a test pattern reticle.
Exposure was carried out using a SW reduction projection exposure device while changing the exposure time while shifting the exposure positions so as not to overlap, and using a 2.4% by weight aqueous solution of tetramethylammonium hydroxide at 60%
Developed for seconds, rinsed with water, and dried.

Using a scanning electron microscope, the resulting resist pattern is exposed to an exposure time (hereinafter referred to as the optimum exposure time) that will accurately form a line-and-space pattern with a resist pattern of 1°2 μm or more after development. ), the sensitivity was 0.40 seconds, which was good, and no scum-like development residue was observed. Further, when the minimum resist pattern dimension (hereinafter referred to as "resolution") at the optimum exposure time was determined, it was 0.8 μm, indicating a high resolution. Furthermore, when a wafer with a resist pattern formed thereon was placed in the open state and the temperature at which the pattern began to collapse was determined, it was 150° C., indicating that the resist had good heat resistance. Furthermore, the adhesiveness between the resist and the substrate was good, and the etching solution did not penetrate between the resist and the substrate, and the wet etching properties were good. The results are shown in Table-1.

(Examples 2 to 8) Using m-cresol and p-cresol shown in Table 1, novolac resins were synthesized in the same manner as in Example 1, and G
The molecular weight distribution of the Novola 7 resin was measured using the PC measurement method. The results are shown in Table-1.

Next, a composition solution of the present invention was prepared in the same manner as in Example 1 except for using the 1,2-quinonediazide compound of the type and amount shown in Table 1, filtered, and the resist performance was evaluated. The results are shown in Table-1. All had excellent sensitivity, resolution, developability, heat resistance, and wet etching properties.

(Comparative Example 1) Into a separable flask similar to Example 1, 108 g (1 mol) of m-cresol, 864 g (8 mol) of p-cresol, 770 g of a 37% formaldehyde aqueous solution, and 0.45 g of oxalic acid were charged. The separable flask was immersed in an oil bath and reacted for 1 hour while maintaining the internal temperature at 100°C. Next, as the reaction progressed, 108 g (1 mol) of m-cresol was continuously charged into a separable flask and reacted for 2 hours. After that, the same treatment as in Example 1 was carried out to determine the molecular weight distribution of the novolak resin using the GPC method. It was measured. The results are shown in Table-1.

Next, a composition solution was prepared in the same manner as in Example 1 except that the 1,2-quinonediazide compound of the type and amount shown in Table 1 was used, filtered, and the resist performance was evaluated. The results are shown in Table 1, and the sensitivity, developability, resolution, heat resistance, and wet etching properties were inferior to those of the Examples. (Comparative Example 2) - 432 g (4 moles) of cresol, 648 g (6 moles) of p-cresol, 770 g of a 37% by weight formaldehyde aqueous solution, and 0.45 g of oxalic acid were charged all at once, the separable flask was immersed in an oil bath, and the internal temperature was adjusted to 100°C. The mixture was reacted for 3 hours while maintaining the temperature, and then treated in the same manner as in Example 1, and the molecular weight distribution of the novolak resin was measured by GPC method. The results are shown in Table-1.

Next, 1. of the types and amounts shown in Table 1. A composition solution was prepared in the same manner as in Example 1 using a 2-quinonediazide compound, filtered, and the resist performance was evaluated. The results are shown in Table 1, and the sensitivity, resolution, developability, heat resistance, and wet etching properties were inferior to those of the Examples.

(Comparative Example 3) 648 g (6 mol) of m-cresol, 432 g (4 mol) of p-cresol, 770 g of a 37% by weight formaldehyde aqueous solution, and 0.45 g of oxalic acid were placed in a separable flask similar to that in Example 1, and a separable flask was charged with 0.45 g of oxalic acid. Immerse the flask in an oil bath and let it react for 1 hour while keeping the temperature at 100°C.
Thereafter, it was treated in the same manner as in Example 1, and the molecular weight distribution of the novolac resin was measured by GPC method. The results are shown in Table-1.

Next, a composition solution was prepared in the same manner as in Example 1 except for using the 1,2-quinonediazide compound of the type and amount shown in Table 1, and filtered. The resist performance was evaluated. The results are shown in Table 1, and the sensitivity, resolution, developability, heat resistance, and wet etching properties were inferior to those of the Examples.

(Comparative Example 4) 648 g (6 moles) of m-cresol, 432 g (4 moles) of p-cresol, 770 g of a 37% by weight formaldehyde aqueous solution, and 9 g of oxalic acid were placed in a separable flask similar to that in Example 1, and the separable flask was heated with oil. Soak in the bath;
The reaction was carried out for 1 hour while maintaining the internal temperature at 100° C., and then the same treatment as in Example 1 was carried out, and the molecular weight distribution of the novolak resin was measured by GPC method. The results are shown in Table-1.

Next, a composition solution was prepared in the same manner as in Example 1 except that the 1,2-quinonediazide compound of the type and amount shown in Table 1 was used, filtered, and the resist performance was evaluated. The results are shown in Table 1, and the sensitivity, resolution, developability, heat resistance, and wet etching properties were inferior to those of the Examples.

(Example 9) A resist layer was formed in the same manner as in Example 1.

Next, the resist performance was evaluated in the same manner as in Example 1 except that a Canon FPA-1550 reduction projection exposure apparatus equipped with a test pattern reticle was used, and the optimum exposure time was 0.30 seconds, indicating high sensitivity. No scum-like development residue was observed. Also, the resolution is 0.7μ
m, and a very high resolution was obtained.

(Example 10) A resist layer was formed in the same manner as in Example 1.

Next, resist performance was evaluated in the same manner as in Example 1, using a Canon FPA-1550 reduction projection exposure apparatus equipped with a test pattern reticle, except that development was performed with a 2.2% by weight aqueous solution of tetramethylammonium hydroxide. The optimum exposure time was 0.6 seconds, indicating high sensitivity, and no scum-like development residue was observed. Further, the resolution was 0.6 μm, and a very high resolution was obtained.

(Effects of the Invention) By using a specific alkali-soluble novolac resin, the positive radiation-sensitive resin composition of the present invention has high sensitivity and good developability, and resist patterns with a line width of 1 μm or less can be solved. It has good dry etching resistance, wet etching resistance and heat resistance.

The positive radiation-sensitive resin composition of the present invention is sensitive to radiation such as ultraviolet rays, far ultraviolet rays, X-rays, electron beams, molecular beams, T-rays, synchrotron radiation, and proton beams, and is particularly suitable for highly integrated circuits. This is suitable as a manufacturing resist.

Claims (1)

[Claims] In a positive radiation-sensitive resin composition comprising an alkali-soluble novolac resin and a 1,2-quinonediazide compound, the alkali-soluble novolak resin contains 30 to 70 mol% of m-cresol and 70 to 70 mol% of p-cresol.
Obtained by condensing a mixed cresol containing 30 mol% with a carbonyl compound, and having a polystyrene equivalent molecular weight of 6,300 to 25,000 as determined by gel permeation chromatography using monodisperse polystyrene as a standard.
, when the maximum heights in the ranges of 2500-6000 and 150-900 are a, b, and c, respectively, a
A positive radiation-sensitive resin composition characterized in that it uses an alkali-soluble novolac resin having c/b=0.4 to 1.5 and c/b=0.4 to 2.