JPH0519464A - Positive type resist composition - Google Patents

Abstract

PURPOSE:To obtain a resist compsn. having excellent sensitivity, heat resistance, resolution and pattern shape, especially improved dimensional faithfulness and focus allowance by incorporating alkali-soluble novolak resin and a radiation sensitive component and using specified quinonediazidosulfonic ester as the radiation sensitive component. CONSTITUTION:Novolak resin consisting of m-cresol and 2,3-xylenol, 3,4-xylenol or 2,3,5-trimethylphenol is blended with quinonediazidosulfonic ester of a phenolic compd. represented by formula I, wherein each of R1-R4 is optionally substd. or unsubstd.,aryl or hydroxyl, at least one among R1, R2 and R4 is hydroxyl, each of R5-R7 is H or optionally substd. alkyl, each of (a), (b) and (d) is an integer of 0-5, all of (a), (b) and (d) are not 0 and (c) is an integer of 0-4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a positive photoresist composition. More specifically, ultraviolet rays, far ultraviolet rays, X
The present invention relates to a positive resist composition suitable as a resist for forming highly integrated circuits, which is sensitive to radiation such as rays, electron rays, molecular rays, γ rays, synchrotron radiation, and proton beams.

[0002]

2. Description of the Related Art Positive resists are often used in the manufacture of integrated circuits because they provide resist patterns of high resolution. With the recent trend toward higher integration of integrated circuits, resist patterns with higher resolution have been obtained. There is a demand for a positive type resist capable of forming a film. That is, when a fine resist pattern is formed with a positive resist, when a latent image formed by irradiation with radiation such as ultraviolet rays is developed with a developer composed of an alkaline aqueous solution, a portion where the irradiation portion is in contact with the wafer ( It is necessary to develop quickly to the bottom of the pattern.

However, in the case of the conventional positive type resist, when the distance between the resist patterns to be formed is 0.8 μm or less, the pattern shape of the fine pattern is insufficient.

Further, as the line width of the pattern becomes narrower, the design dimension of the mask tends to deviate from the actual dimension of the resist pattern. A resist faithful to the design dimension of the mask (a resist having a good dimension fidelity) with a small amount of this deviation is required for manufacturing an integrated circuit having a high degree of integration, but the conventional positive type resist is not satisfactory. ..

Further, as the degree of integration of the integrated circuit is improved,
The wafer etching method is shifting from the conventional wet etching with large side etching to dry etching with small side etching. In this dry etching, since it is necessary that the resist pattern does not change due to heat during etching, the positive resist must have heat resistance, but the conventional positive resist is
It was difficult to say that it had sufficient heat resistance.

Further, the conventional positive resist has a sufficient focus allowance because the pattern shape is deformed, the developability is deteriorated, the deviation from the design line width is remarkable when the focus is deviated during exposure by the stepper. I didn't have it.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive photoresist composition. Another object of the present invention is to provide a positive resist composition which is excellent in sensitivity, heat resistance, resolution and pattern shape, and particularly suitable as a positive resist having good dimensional fidelity and focus tolerance. is there. Further objects and advantages of the present invention will be apparent from the following description.

[0008]

According to the present invention, the above objects and advantages of the present invention are a positive photoresist composition containing an alkali-soluble novolac resin and a radiation-sensitive component, which comprises (A) The alkali-soluble novolak resin is obtained by polycondensing (A1) metacresol, 2,3-xylenol and 3,4-xylenol with aldehydes, wherein metacresol / 2,3-xylenol / 3 The molar ratio of 4,4-xylenol is 90 to 10/5 to 85/5 to 60, or

(A2) Alkali-soluble novolac resin obtained by polycondensing metacresol and 2,3,5-trimethylphenol, or these and 2,3-xylenol with aldehydes, wherein metacresol / 2,3 , 5
The molar ratio of trimethylphenol / 2,3-xylenol is 95 to 10/5 to 60/0 to 85, and (B) the radiation-sensitive component is represented by the following formula (1).

[0010]

[Chemical 2]

Here, R ^{1 to} R ⁴ are the same or different and are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a hydroxyl group (provided that R ¹ and R ^{2 are}
And at least one of R ⁴ is a hydroxyl group), R ^{5 to} R ⁷ are the same or different and each is a hydrogen atom or a substituted or unsubstituted alkyl group, and a, b and d are 0 to 5 Is an integer (provided that a, b and d are not all 0), and c is an integer of 0 to 4, provided that when a is 2 to 5, a plurality of R ¹ , b are obtained. Is 2
Plural R ² in the case of ˜5, plural R ^{3 in} the case of c being 2 to 4
And a plurality of R ⁴ 's when d is 2 to 5 may be the same or different, respectively, 1,2-quinonediazide sulfone of the phenolic compound represented by (hereinafter referred to as “specific phenol compound”) This is achieved by a positive photoresist composition which is an acid ester.

The alkali-soluble novolak resin used in the present invention (hereinafter referred to as "novolak resin")
Is metacresol, 2,3-xylenol and 3,4
-Novolak resin (A1) obtained by polycondensing xylenol with aldehydes or metacresol and 2,3,5-trimethylphenol or these and 2,3
A novolak resin (A2) obtained by polycondensing xylenol with aldehydes.

In the synthesis of the novolak resin, the amount of these metacresols (poly) methyl-substituted phenols consisting of 2,3-xylenol, 3,4-xylenol and 2,3,5-trimethylphenol is metacresol, In the case of a novolac resin (A1) obtained by polycondensing 2,3-xylenol and 3,4-xylenol with aldehydes, usually metacresol / 2,
3-xylenol / 3,4-xylenol = 90-10
/ 5 to 85/5 to 60 (molar ratio), preferably metacresol / 2,3-xylenol / 3,4-xylenol =
It is 80 to 20/10 to 70/10 to 50 (molar ratio).

Here, metacresol is 90 (molar ratio).
If it exceeds 10, the pattern shape is deteriorated, if it is less than 10 (molar ratio), the sensitivity and resolution are deteriorated, and if 2,3-xylenol exceeds 85 (molar ratio), the developability is deteriorated and 5 ( If it is less than the molar ratio), the dimensional fidelity and focus tolerance are deteriorated, and 3,4-xylenol is 60% or less.
If the (molar ratio) is exceeded, the sensitivity and heat resistance deteriorate, and 5
When it is less than (molar ratio), the resolution and the pattern shape are deteriorated.

Further, in the case of a novolac resin (A2) obtained by polycondensing meta-cresol and 2,3,5-trimethylphenol or those and 2,3-xylenol using aldehydes, usually, Cresol / 2,
The molar ratio of 3,5-trimethylphenol / 2,3-xylenol is 95 to 10/5 to 60/0 to 85, preferably 90 to 50/10 to 50/0 to 70.

Here, metacresol is 95 (molar ratio).
When it exceeds 10, the pattern shape deteriorates, and when it is less than 10 (molar ratio), the sensitivity and resolution deteriorate, and when 2,3,5-trimethylphenol exceeds 60 (molar ratio), the sensitivity deteriorates, When it is less than 5 (molar ratio), the pattern shape,
Developability and heat resistance deteriorate, and when 2,3-xylenol exceeds 85 (molar ratio), dimensional fidelity and focus tolerance deteriorate. The object of the present invention can be achieved only by using the specific novolac resin as described above.

Examples of aldehydes used here include formaldehyde, trioxane, paraformaldehyde, benzaldehyde, acetaldehyde, propylaldehyde, phenylacetaldehyde,
α-phenylpropyl aldehyde, β-phenylpropyl aldehyde, o-hydroxybenzaldehyde, m-
Hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde,
Examples thereof include p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde and furfural. Of these, formaldehyde can be preferably used. These aldehydes can be used alone or in combination of two or more kinds.

The amount of the above-mentioned aldehydes used is based on 1 mol of the total amount of the (poly) methyl-substituted phenol used.
The amount is preferably 0.7 to 3 mol, more preferably 0.8 to 1.
It is 5 mol. Examples of the catalyst used for polycondensation of (poly) methyl-substituted phenol and aldehydes include acidic catalysts such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid and acetic acid. The amount of these acidic catalysts used is usually
Based on 1 mol of the total amount of (poly) methyl-substituted phenol,
It is 1 × 10 ^{−5 to} 5 × 10 ⁻¹ mol.

In the polycondensation, water is usually used as the reaction medium, but when the (poly) methyl-substituted phenol used in the polycondensation does not dissolve in the aqueous solution of aldehydes and becomes heterogeneous from the initial reaction, It is also possible to use hydrophilic solvents as reaction medium. Examples of these hydrophilic solvents include methanol, ethanol, propanol,
Examples thereof include alcohols such as butanol, and cyclic ethers such as tetrahydrofuran and dioxane. The amount of these reaction media used is usually 20 to 1,000 parts by weight per 100 parts by weight of the reaction raw material.

The polycondensation temperature can be appropriately adjusted depending on the reactivity of the reaction raw materials, but is usually 10 to 200 ° C.
Is. As the polycondensation method, a method in which (poly) methyl-substituted phenols, aldehydes, acidic catalysts and the like are charged all at once, and (poly) methyl-substituted phenols, aldehydes and the like in the presence of acidic catalysts are used as the reaction progresses. The method of adding can be adopted.

After completion of the polycondensation, in order to remove unreacted raw materials, acidic catalyst, reaction medium and the like existing in the system, generally, the temperature of the reaction system is raised to 130 to 230 ° C. and reduced pressure is applied. The volatile matter is distilled off at, for example, about 20 to 50 mmHg, and the obtained novolac resin is recovered.

The novolak resin used in the present invention has a polystyrene-reduced weight average molecular weight (hereinafter referred to as "Mw").
Is usually in the range of 4,000 to 20,000, particularly preferably 5,000 to 15,000.
When the Mw exceeds 20,000, it becomes difficult to uniformly apply the composition of the present invention to a wafer, and further developability and sensitivity decrease, and when the Mw is less than 4,000, heat resistance tends to decrease. There is.

In order to obtain a novolak resin having a high Mw, for example, the resin (A) recovered after completion of polycondensation
Was dissolved in a good solvent such as ethyl cellosolve acetate, dioxane, methanol and ethyl acetate, and then water and n-
It is advisable to mix a poor solvent such as hexane or n-heptane, then separate the resin solution layer that precipitates, and recover the high molecular weight novolak resin.

Further, a low molecular weight phenol compound may be used as a dissolution accelerator for the purpose of promoting alkali solubility of the novolak resin. As the low molecular weight compound used here, a phenol compound having about 2 to 6 benzene rings is suitable, and examples thereof include compounds represented by the following formula.

[0025]

[Chemical 3]

Here, a, b, and c are 0 to 0, respectively.
It is a number of 3 (however, when both are 0), x,
y and z are numbers from 0 to 3.

The amount of the low molecular weight phenolic compound to be added is usually 50 parts by weight or less, particularly 5 to 30 parts by weight, per 100 parts by weight of the novolak resin.

As the 1,2-quinonediazidesulfonic acid ester (B) used in the present invention, 1,2-quinonediazidesulfonic acid ester of a specific phenol compound is used.

In the above formula (1), R ^{1 to} R ⁴ are
They are the same or different and each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a hydroxyl group. Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, a cyclohexyl group,
Examples thereof include hydroxymethyl group, chloromethyl group, bromomethyl group, benzyl group, cumyl group and the like. Of these, a methyl group, an ethyl group, a hydroxymethyl group and the like are preferable. Examples of the substituted or unsubstituted aryl group include phenyl group, 1-naphthyl group, 2-naphthyl group, 4
-Hydroxyphenyl group, 4-trimethylsiloxyphenyl group, 4-methoxyphenyl group, 4-acetylphenyl group and the like can be mentioned. Among them, phenyl group,
A 4-hydroxyphenyl group and the like are preferable.

R ⁵ , R ⁶ and R ⁷ each represent a hydrogen atom or a substituted or unsubstituted alkyl group. Examples of such substituted or unsubstituted alkyl group include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n
-Butyl group, t-butyl group, cyclohexyl group, hydroxymethyl group, chloromethyl group, bromomethyl group, benzyl group, cumyl group and the like can be mentioned. Of these, a methyl group, an ethyl group, a hydroxymethyl group and the like are preferable.

Specific examples of the specific phenol compound include bis (4-hydroxyphenyl) -4- [1- {4-hydroxyphenyl} ethyl] phenylmethane and bis (4
-Hydroxyphenyl) -4- {1- (4-hydroxyphenyl) -1-methylethyl} phenylmethane, bis (2,5-dimethyl-4-hydroxyphenyl) -4-
{1- (2,5-dimethyl-4-hydroxyphenyl}
Ethyl) phenylmethane, bis (2,5-dimethyl-4)
-Hydroxyphenyl) -4- {1- (2,5-dimethyl-4-hydroxyphenyl) -1-methylethyl} phenylmethane, 1,1-bis (4-hydroxyphenyl) -1- [4- {1 -(4-hydroxyphenyl) ethyl} phenyl] ethane, 1,1-bis (4-hydroxyphenyl) -1- [4- {1- (4-hydroxyphenyl) -1-methylethyl} phenyl] ethane, 1 , 1
-Bis (2,5-dimethyl-4-hydroxyphenyl)
-1- [4- {1- (2,5-dimethyl-4-hydroxyphenyl) -1-methylethyl} phenyl] ethane,
1,1-bis (3,5-dimethyl-4-hydroxyphenyl) -1- [4- {1- (3,5-dimethyl-4-hydroxyphenyl) -1-methylethyl} phenyl] ethane, 1, 1-bis (3,5-dimethyl-2-hydroxyphenyl) -1- [4- {1- (3,5-dimethyl-2-
Hydroxyphenyl) -1-methylethyl} phenyl]
Ethane and 1,1-bis (3,5-dimethoxy-4-)
Examples thereof include hydroxyphenyl) -1- [4- {1- (3,5-dimethoxy-4-hydroxyphenyl) -1-methylethyl} phenyl] ethane.

These specific phenol compounds can be obtained, for example, by reacting a substituted or unsubstituted phenol with an olefin-substituted aromatic carbonyl compound in the presence of an acidic catalyst.

The 1,2-quinonediazidesulfonic acid ester (B) of the specific phenolic compound which is the radiation-sensitive component in the present invention includes, for example, 1,2-benzoquinonediazide-4-sulfonic acid ester of the specific phenolic compound, 1,2 2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,1-naphthoquinonediazide-4-sulfonic acid ester, 2,1-naphthoquinonediazide-5
-Sulfonic acid esters and the like can be mentioned. Among them, preferred is 1,2-naphthoquinonediazide-4-
Sulfonic acid ester and 1,2-naphthoquinonediazide-5-sulfonic acid ester.

The 1,2-quinonediazide sulfonic acid ester (B) is, for example, a specific phenol compound and 1,2-quinone diazide sulfonic acid ester (B).
Naphthoquinonediazide-4-sulfonyl chloride, 1,
It can be obtained by an esterification reaction with 1,2-quinonediazidesulfonyl halide such as 2-naphthoquinonediazide-5-sulfonyl chloride.

In the esterification reaction, the reaction ratio between the specific phenol compound and the 1,2-quinonediazidesulfonyl halide is 1,2-quinonediazidesulfonyl halide per 1 gram equivalent of the hydroxyl group of the specific phenol compound.
It is preferably 0.2 to 1 mol, particularly preferably 0.3 to 0.
It is 95 mol and can be obtained by reacting these in the presence of a basic catalyst.

As the basic catalyst, amines such as trimethylamine, triethylamine, tripropylamine, pyridine and tetramethylammonium hydroxide and inorganic alkalis such as sodium hydroxide, potassium hydroxide and sodium carbonate are used as the basic catalyst. Be done.
The amount of these basic catalysts used is usually 1 mol of 1,2-quinonediazidesulfonyl halide used.
It is 0.8-2 mol, preferably 1-1.5 mol. The esterification reaction is usually performed in the presence of a solvent.
Examples of the solvent used at this time include dioxane, diethyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, γ-butyl lactone, N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, ethylene carbonate, propylene carbonate and the like. Is mentioned. The amount of these solvents used is usually 1
It is 100 to 1,000 parts by weight with respect to 00 parts by weight.

The temperature of the esterification reaction varies depending on the solvent used, but is usually -30 to 60 ° C, preferably 0 to
40 ° C.

As a purification method after the esterification reaction, the hydrochloride produced as a by-product is filtered, or water is added to dissolve the hydrochloride, followed by reprecipitation purification with a large amount of acidic water such as dilute hydrochloric acid aqueous solution. The method of drying after doing can be illustrated.

These 1,2-quinonediazide sulfonic acid esters (B) may be used either individually or in combination of two or more. The amount used is usually 100 parts by weight of novolak resin. 3 to 100 parts by weight,
It is preferably 5 to 50 parts by weight.

When the 1,2-quinonediazide sulfonic acid ester (B) exceeds 100 parts by weight, the sensitivity and developability tend to deteriorate, and when it is less than 3 parts by weight, the resolution tends to deteriorate. is there.

Further, 1,2-quinonediazide sulfonic acid ester other than 1,2-quinonediazide sulfonic acid ester (B) may be blended within a range that does not impair the effects of the present invention. Examples of such 1,2-quinonediazide sulfonic acid ester include 2,3,4-trihydroxybenzophenone, 2,4,4′-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone and 3 '-Methoxy-2,3,4,4'-tetrahydroxybenzophenone, 2,2', 5,5'-tetramethyl-2 ", 4,4'-trihydroxytriphenylmethane, 1,1,1- Tris (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl)
-4 '-[1- (4-hydroxyphenyl) -1-methylethyl] -1-phenylethane and 1 of 2,4,4-trimethyl-2', 4 ', 7-trihydroxy-2-phenylflavan 2,2-naphthoquinonediazide-5-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester and the like can be mentioned.

In the composition of the present invention, if necessary,
Various compounding agents such as a sensitizer and a surfactant can be added. The sensitizer is added to improve the sensitivity of the resist, and examples of such a sensitizer include 2H-pyrido- (3,2-b) -1,4-oxazine-.
3 (4H) -ones, 10H-pyrido- (3,2-b)
-(1,4) -benzothiazines, urazoles, hydantoins, parbituric acids, glycine anhydrides, 1
-Hydroxybenzotriazoles, alloxans, maleimides and the like can be mentioned. The compounding amount of these sensitizers is usually 50 parts by weight or less with respect to 100 parts by weight of the novolac resin.

The surfactant is added to improve the coatability and developability of the composition. Examples of such a surfactant include polyoxyethylene lauryl ether and polyoxyethylene oleyl ether. , Polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, Ftop EF301, EF303, EF35
2 (brand name, manufactured by Shin-Akita Kasei Co., Ltd.), Megafax F1
71, F172, F173 (trade name, manufactured by Dainippon Ink and Chemicals), Florard FC430, FC431 (trade name,
Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, S
C-103, SC-104, SC-105, SC-10
6 (trade name, manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), acrylic acid-based or methacrylic acid-based (co) polymer Polyflow N
No. 75, No. 95 (trade name, manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.) and the like. The blending amount of these surfactants is
It is usually 2 parts by weight or less per 100 parts by weight of the solid content of the composition.

Further, in the composition of the present invention, a dye or a pigment can be blended in order to visualize the latent image in the radiation-irradiated portion and reduce the influence of halation during radiation irradiation, and improve the adhesiveness. In order to do so, an adhesion aid can be added. Further, if necessary, a storage stabilizer, a defoaming agent and the like can be added.

The composition of the present invention contains the above-mentioned novolac resin, 1,2-quinonediazide sulfonic acid ester (B) of a specific phenol compound as a radiation-sensitive component, and various kinds of compounding agents as necessary, for example, in a solid content concentration. Two
It is dissolved in a solvent so as to be 0 to 40% by weight, and the pore size is 0.1.
It can be prepared by filtering with a filter of about 2 μm.

Examples of the solvent used at this time include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and methyl cellosolve acetate.
Ethyl cellosolve acetate, diethylene glycol
Rumonomethyl ether, diethylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl 2-hydroxypropionate, 2
-Ethyl hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, 3 -Methyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate and the like can be used. These organic solvents may be used alone or in combination of two or more.

Furthermore, N-methylformamide, N, N
-Dimethylformamide, N-methylformanilide,
N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, benzyl ethyl ether, dihexyl ether, acetonyl acetone, isophorone, caproic acid, caprylic acid, 1
-Octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenyl cellosolve acetate-
It is also possible to add a high-boiling point solvent such as g.

The composition of the present invention is applied to a silicon wafer or a wafer coated with aluminum by spin coating, flow coating, roll coating, or the like to form a radiation-sensitive layer, and the composition of the present invention is prepared. A pattern is formed by irradiating the radiation-sensitive layer with radiation through a mask pattern and developing with a developing solution.

The composition of the present invention is obtained by applying the composition onto a wafer or the like, performing prebaking and irradiation with radiation, then performing PEB operation of heating at 70 to 140 ° C., and then developing. The effect of the present invention can be further improved.

The developer of the composition of the present invention includes, for example, sodium hydroxide, potassium hydroxide, sodium carbonate,
Sodium silicate, sodium metasilicate, aqueous ammonia,
Ethylamine, n-propylamine, diethylamine,
Di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide,
Tetraethylammonium hydroxide, choline, pyrrol, piperidine, 1,8-diazabicyclo (5.4.
0) -7-undecene, 1,5-diazabicyclo- (4.
An alkaline aqueous solution prepared by dissolving an alkaline compound such as 3.0) -5-nonane to a concentration of, for example, 1 to 10% by weight is used.

Further, a water-soluble organic solvent, for example, alcohols such as methanol and ethanol, and a surfactant may be added to the developing solution in an appropriate amount. When developing is performed using a developing solution composed of such an alkaline aqueous solution, generally, rinsing with water is subsequently performed.

[0052]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The measurement of Mw and the evaluation of the resist in the examples are carried out by the following methods.

Mw: Tosoh GPC column (G200
0H6 2 Pieces, G3000H6 1 Piece, G4000H6
(1 bottle), the flow rate was 1.5 ml / min, the elution solvent was tetrahydrofuran, and the column temperature was 40 ° C., and the gel permeation chromatographic method using monodisperse polystyrene as a standard was used for measurement.

Resolution: Nikon NSR-1755G7
A reduction projection exposure machine (numerical aperture of lens; 0.54) was used to change the exposure time, and exposure was performed using g-line with a wavelength of 436 nm, or NSR-1755i7A reduction projection exposure machine manufactured by Nikon Corporation (lens numerical aperture). 0.50), the exposure time is changed, exposure is performed using an i-ray having a wavelength of 365 nm, heat treatment is performed at 110 ° C. for 120 seconds, and then tetramethylammonium hydroxide 2.4% by weight is added.
Using an aqueous solution as a developing solution, developing at 25 ° C. for 60 seconds,
When rinsing with water and drying to form a resist pattern on the wafer, and exposing with the exposure time (optimum exposure time) that forms a line-and-space pattern (1L1S) of 0.6 μm in a width of 1: 1 The dimension of the smallest resist pattern that was resolved was measured.

Pattern shape: Using a scanning electron microscope (Hitachi; S-530), the pattern shape of the 0.6 μm resist pattern after development was examined.

Dimensional fidelity: exposure is performed at the optimum exposure time, and the mask dimension of the line and space pattern is 0.02
Scanning electron microscope (Hitachi, Ltd.) shows how the resist line and space pattern size deviates from the actual mask line and space pattern design size when the size is reduced in μm intervals. S-700
0) was used. The case where the difference between the pattern dimension and the design dimension of the mask was within ± 10% of the design dimension of the mask was regarded as acceptable. The design dimension of the passed mask was used as the dimension fidelity as an evaluation index. Poor dimensional fidelity means having good dimensional fidelity.

Focus range: Scanning electron microscope (Hitachi; S-7000) was used to detect a line of 0.6 μm.
In the and space pattern, when the pattern size to be resolved is within ± 10% of the design size of the mask, the focus swing range is used as the focus range and is used as the evaluation index. A large focus range means that it has a good focus tolerance.

<Synthesis of Novolac Resin> Synthesis Example 1 In a flask equipped with a stirrer, a condenser and a thermometer, 95.2 g (0.88 mol) of meta-cresol 2,3,5-trimethylphenol (24.4 g) was added. 18 mol) 37% by weight formaldehyde aqueous solution 154 g (formaldehyde: 1.90 mol) and oxalic acid dihydrate 1.82 g (0.014 mol) were charged, the flask was immersed in an oil bath, and the internal temperature was kept at 100 ° C. Then, polycondensation was carried out for 90 minutes while stirring, and then 23.8 g (0.22 mol) of meta-cresol and 97.6 g (0.72 mol) of 2,3,5-trimethylphenol were added for another 60 minutes. Polycondensation was performed.

Then the oil bath temperature is raised to 180 ° C.,
At the same time, reduce the pressure in the flask to 30-40 mmHg,
Water, oxalic acid, unreacted formaldehyde, metacresol, 2,3,5-trimethylphenol, etc. were removed.
Then, the molten resin was returned to room temperature and recovered.

This resin was dissolved in ethyl cellosolve acetate so that the solid content was 30% by weight, and then 0.3 times of methanol and 0.7 times the weight of this resin solution was added.
Water was added 5 times, and the mixture was stirred and left to stand. After separating into two layers by standing, the resin solution layer (lower layer) was taken out, concentrated, dehydrated and dried to recover the resin. This resin is called resin (A1).

Synthesis Example 2 Metacresol 110.0 g (1.02 mol) 2,3-xylenol 62.3 g (0.51 mol) 2,3,5-trimethylphenol 23.2 g (0.17 mol) were placed in an autoclave. 37% by weight formaldehyde aqueous solution 150 g (formaldehyde: 1.70 mol) oxalic acid dihydrate 4.28 g (0.034 mol) Water 59.7 g and dioxane 440 g were charged, the autoclave was immersed in an oil bath, and the internal temperature was adjusted to 130.
Polycondensation was carried out for 8 hours while maintaining the temperature at 0 ° C. with stirring. After the reaction, the temperature was returned to room temperature and the contents were taken out in a beaker. After separating into two layers in this beaker, take out the lower layer,
The resin was recovered by concentrating, dehydrating and drying. This resin is called resin (A2).

Synthesis Example 3 Metacresol 86.5 g (0.8 mol) 2,3,5-trimethylphenol 27.2 g (0.2 mol) 37 wt% aqueous formaldehyde solution 75.1 g (formaldehyde: 0.925) in an autoclave. Mol) oxalic acid dihydrate 6.30 g (0.05 mol) water 66.4 g and dioxane 341.1 g were charged, the autoclave was immersed in an oil bath, and the internal temperature was adjusted to 130.
Polycondensation was carried out for 7 hours while maintaining the temperature at 0 ° C. with stirring. After the reaction, the temperature was returned to room temperature, and the contents were taken out in a beaker. After separating into two layers in this beaker, take out the lower layer,
The resin was recovered by concentrating, dehydrating and drying. This resin is called resin (A3).

Synthesis Example 4 Metacresol 97.3 g (0.90 mol) 2,3-xylenol 36.7 g (0.30 mol) 3,4-xylenol 36.7 g (0.30 mol) 37% by weight in an autoclave Formaldehyde aqueous solution 113 g (formaldehyde: 1.39 mol) Oxalic acid dihydrate 9.45 g (0.075 mol) 121 g of water and 576 g of dioxane were charged, the autoclave was immersed in an oil bath, and the internal temperature was set to 130.
Polycondensation was carried out for 8 hours while maintaining the temperature at 0 ° C. with stirring. After the reaction, the temperature was returned to room temperature, and the contents were taken out in a beaker. After separating into two layers in this beaker, take out the lower layer,
The resin was recovered by concentrating, dehydrating and drying. This resin is called resin (A4).

Synthesis Example 5 In a flask similar to that used in Synthesis Example 1, metacresol 51.9 g (0.48 mol) 2,3-xylenol 4.88 g (0.04 mol) 2,3,5- Trimethylphenol 5.42 g (0.04 mol) 37% by weight aqueous formaldehyde solution 77.0 g (formaldehyde: 0.95 mol) and oxalic acid dihydrate 1.82 g (0.014 mol) were charged, and the flask was placed in an oil bath. After performing polycondensation for 90 minutes with stirring while maintaining the internal temperature at 100 ° C.,

Metacresol 13.0 g (0.12 mol) 2,3-xylenol 19.5 g (0.16 mol) and 2,3,5-trimethylphenol 21.7 g (0.16 mol) were further added. Polycondensation was carried out for 60 minutes.

Then the oil bath temperature is raised to 180 ° C.,
At the same time, reduce the pressure in the flask to 30-40 mmHg,
Water, oxalic acid, unreacted formaldehyde, metacresol, 2,3-xylenol, 2,3,5-trimethylphenol, etc. were removed. Then, the molten resin was returned to room temperature and recovered.

This resin was mixed with ethyl acetate to obtain a solid content of 3
After the solution was dissolved to 0% by weight, 0.3 times of methanol and 1.2 times of water were added to the weight of the resin solution, and the mixture was stirred and left to stand. After separating into two layers by standing, the resin solution layer (lower layer) was taken out, concentrated, dehydrated and dried to recover the resin. This resin is called resin (A
5).

<Abbreviated name of specific phenol compound> In the following, 1,1, -bis (4-hydroxyphenyl) -1- [4-
{1- (4-Hydroxyphenyl) -1-methylethyl} phenyl] ethane as compound (P1), bis (4-hydroxyphenyl) -4- {1- (4-hydroxyphenyl) -1-methylethyl} phenyl Methane is abbreviated as compound (P2).

<Synthesis of 1,2-quinonediazidesulfonic acid ester (B)> Synthesis Example 6 In a flask equipped with a stirrer, a dropping funnel and a thermometer under light shielding, 42.5 g (0.1 mol of compound (P1)) was added. ) 1,2-naphthoquinonediazide-5-sulfonic acid chloride 53.7 g (0.2 mol) and dioxane 100 g were charged and dissolved with stirring. Then, the flask was immersed in a water bath maintained at 30 ° C, and when the internal temperature became constant at 30 ° C, 22.3 g (0.22 mol) of triethylamine was added to this solution so that the internal temperature did not exceed 35 ° C. The solution was slowly added dropwise to the above using a dropping funnel.

Thereafter, the precipitated triethylamine hydrochloride was removed by filtration, the filtrate was poured into a large amount of dilute hydrochloric acid to cause precipitation, and then the precipitate was collected by filtration and dried in a vacuum drier kept at 40 ° C. for one day and 1, 2-quinonediazide sulfonic acid ester (B) was obtained. This 1,2-quinonediazide sulfonic acid ester (B) is referred to as NQD1.

Synthesis Example 7 Compound (P1) 30.6 g (0.1 mol) 1,2-naphthoquinonediazide-5-sulfonic acid chloride 67.1 g (0.25 mol) dioxane 100 g and triethylamine 27.9 g (0.1 mol). 275 mol) was used in the same manner as in Synthesis Example 6 to obtain 1,2-quinonediazidesulfonic acid ester (B). This 1,2-
The quinonediazide sulfonic acid ester (B) is referred to as NQD2.

Synthesis Example 8 Compound (A2) 42.5 g (0.1 mol) 1,2-naphthoquinonediazide-4-sulfonic acid chloride 53.7 g (0.20 mol) dioxane 100 g and triethylamine 22.3 g (0.1 mol). 22 mol) was used, and 1,2-quinonediazidesulfonic acid ester (B) was obtained in the same manner as in Synthesis Example 6. This 1,2-
The quinonediazide sulfonic acid ester (B) is referred to as NQD3.

Examples 1 to 8 and Comparative Examples 1 to 3 The novolac resin, 1,2-quinonediazide sulfonic acid ester (B) and solvent shown in the synthesis examples, and, if necessary, the 1,2-quinonediazide sulfone. A 1,2-quinonediazide sulfonic acid ester other than the acid ester (B), a dissolution promoter and the like were mixed to form a uniform solution, which was then filtered through a membrane filter having a pore size of 0.2 μm to prepare a solution of the composition. The obtained solution was applied on a silicon wafer having a silicon oxide film by using a spinner, and then on a hot plate at 90 ° C. for 1.
Pre-baking is performed for 5 minutes to form a 1.2 μm-thick resist film, and a wavelength of 436 μm is applied through the reticle as described above.
m (g-line) or wavelength 365 μm (i-line) is used for exposure, and PEB operation is performed at 110 ° C. for 120 seconds to develop.
After rinsing and drying, the performance of the resist was examined.
The results are shown in Table 1.

[0074]

[Table 1]

(Note 1) The addition amount is shown in parts by weight. (Note 2) X in the type of novolac resin is as follows. M obtained by the same method as in Example 2 using oxalic acid catalyst with monomers in a ratio of metacresol / paracresol = 6/4 and cresol / formalin = 1/1 (molar ratio).
w: 11000 novolac resin. (Note 3) Dissolution accelerators, α and β are as follows. α: 1,1-bis (4-hydroxyphenyl) cyclohexane β: 1,1-bis (4-hydroxyphenyl) -1-phenylethane

(Note 4) 1,2-quinonediazidesulfonic acid esters other than 1,2-quinonediazidesulfonic acid ester (B), I and II are as follows. I: 2,4,4'-trihydroxybenzophenone 1.
Condensation product of 0 mol and 2.6 mol of 1,2-naphthoquinonediazide-5-sulfonic acid chloride. II: 1.0 mol of 2,3,4,4'-tetrahydroxybenzophenone and 1,2-naphthoquinonediazide-5
Condensate with 4.0 mol of sulfonic acid chloride.

(Note 5) The types of solvent are as follows. S1: Ethyl cellosolve acetate S2: Ethyl 2-hydroxypropionate S3: Methyl 3-methoxypropionate (Note 6) Examples 1 to 3 and Comparative Example 1 were exposed to g rays, and Examples 4 to 8 and Comparative Example were exposed. 2 and 4 were exposed with i-line.

[0078]

The positive resist composition of the present invention is excellent in sensitivity, heat resistance, resolution and pattern shape, and in particular, dimensional fidelity and focus tolerance are remarkably improved. Therefore, the positive resist composition can be suitably used as a resist for producing an integrated circuit with high integration.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Takao Miura 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Synthetic Rubber Co., Ltd.

Claims (1)

Claims: 1. A positive photoresist composition comprising an alkali-soluble novolak resin and a radiation-sensitive component, wherein (A) the alkali-soluble novolac resin is (A1) metacresol, 2, Alkali-soluble novolac resin obtained by polycondensing 3-xylenol and 3,4-xylenol with aldehydes, wherein the molar ratio of metacresol / 2,3-xylenol / 3,4-xylenol is 90 to 10/5. ~ 85/5 to 60, or (A2) an alkali-soluble novolak resin obtained by polycondensing metacresol and 2,3,5-trimethylphenol, or these and 2,3-xylenol with an aldehyde, And the molar ratio of meta-cresol / 2,3,5-trimethylphenol / 2,3-xylenol is 95-1.
0/5 to 60/0 to 85, and (B) the radiation-sensitive component is represented by the following formula (1): Here, R ^{1 to} R ⁴ are the same or different and are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a hydroxyl group (provided that at least one of R ¹ , R ² and R ⁴ is Hydroxyl group), R ⁵ ~
R ⁷ is the same or different and is a hydrogen atom or a substituted or unsubstituted alkyl group, and a, b and d are 0 to
Is an integer of 5 (provided that all of a, b and d are not 0), and c is an integer of 0 to 4, provided that when a is 2 to 5, a plurality of R ¹ , A plurality of R ^{2 s} when b is 2 to 5, a plurality of R ^{3 s} when c is 2 to 4 and a plurality of R ^{4 s} when d is 2 to 5 may be the same or different. The positive resist composition is a 1,2-quinonediazide sulfonic acid ester of a phenolic compound represented by