JPH1069076A - Positive resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the positive resist composition capable of stably obtaining excellent resist characteristics on sensitivity and resolution and film endurance and moreover having excellent storage stability. SOLUTION: The positive resist composition is one of polycyclic phenols obtained by reaction of p-cresol with methylol compounds obtained by reaction between o-cresol and formaldehyde and they comprise 65-95% (GPC pattern area) 4-cyclic phenols and >=10% total lower phenols and 5-25% total higher phenols and have a weight average molecular weight of 510-700 in terms of polystyrene and 40-80mol% of the polycyclic phenols are esterified with a quinonediazidosulfonic acid to form a photosensitive agent. GPC means gell permeation chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist composition, and more particularly to a positive resist composition for fine processing required for manufacturing semiconductor devices, magnetic bubble memory devices, integrated circuits and the like.

[0002]

2. Description of the Related Art In recent years, as a resist composition for forming a semiconductor device, a positive resist composition has become more popular than a negative resist composition. This is due to the fact that the negative resist composition has high sensitivity, but has a problem in resolution due to the use of an organic solvent for development because of the large swelling. On the other hand, it is considered that the positive resist composition can be developed with an alkaline aqueous solution having a small swelling and has excellent resolution, and thus can sufficiently cope with high integration of semiconductors. Conventionally, a positive resist composition generally used in this field comprises an alkali-soluble resin such as a novolak resin and a quinonediazidesulfonic acid compound. This positive resist composition does not swell because it is developed with an aqueous alkali solution, and is excellent in resolution. The resolution of such a positive resist composition has been further improved by improving the performance of the positive resist composition itself and the performance of an exposing machine, and it has become possible to form a fine pattern of 0.5 μm or less.

[0003] However, conventional positive resist compositions do not always provide satisfactory results in terms of various characteristics such as sensitivity, residual film ratio, resolution, heat resistance, and storage stability.
Further improvements in performance are desired. In particular, in the formation of a fine pattern of 0.5 μm or less, it is necessary to more strictly control the resist dimensions. Therefore, a positive resist composition having higher dimensional accuracy has been strongly demanded. From such a viewpoint, quinonediazidesulfonic acid esters having various phenol compounds as a nucleus have been conventionally used as a photosensitive agent (Japanese Patent Publication No. 3-4 / 1991).
896, JP-T4-502519, JP-A-6-167805, JP-A-6-148878, JP-A-7-159989, JP-A-7-168.
355). Further, the use of a novolak-based tetranuclear compound group as a phenol compound as a raw material for a photosensitive agent has been studied (JP-A-7-319158, JP-A-7-225476, JP-A-7-175213, JP-A-7-230166, JP-A-7-219
No. 220). The performance of the photosensitizer in the resist
It depends largely on the phenol compound serving as the core, and the conditions under which the performance is best exhibited may differ for each phenol compound. Thus, sensitivity, residual film ratio,
For the purpose of improving the balance of various properties such as heat resistance, a phenol compound serving as a mother nucleus has been studied as described in each of the above publications. However, among these, although effective in improving the resist properties, some of them have poor storage stability such as an increase in fine particles during storage. The generation of fine particles during storage significantly reduces the yield of microfabrication, and is therefore regarded as a very important problem.

Therefore, the positive resist compositions specifically disclosed in these prior arts can stably obtain excellent resist characteristics with respect to sensitivity, resolution and residual film ratio, and also have excellent storage stability. At present, there is a demand for further improvement of the photosensitive agent in the resist composition, not limited to the conventional resist composition.

[0005]

Under such prior art, the inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by using a quinonediazidesulfonic acid ester of a specific phenol compound, the sensitivity, The inventors have found that high resist characteristics excellent in not only the residual film ratio, the resolution and the pattern shape but also the depth of focus and the exposure margin can be obtained, and the storage stability of the fine particles is also excellent, and the present invention has been completed.

[0006]

Thus, according to the present invention, there is provided a positive resist composition comprising (A) an alkali-soluble phenol resin and (B) a quinonediazidesulfonic acid ester-based photosensitizer of phenols. And (B) a photosensitizer, wherein (a) the phenol is a polynuclear phenol obtained by reacting a methylol compound obtained by reacting orthocresol with formaldehyde and paracresol; A polynuclear phenol is a UV 254 nm detector as a detector,
In the area ratio of the pattern obtained by gel permeation chromatography using tetrahydrofuran as an eluent, the tetranuclear phenols are 65 to 95%, and a substance having a lower molecular weight than the tetranuclear phenols (an unreacted methylol compound and (Including unreacted phenols) is 10% or less, a mixture of 5 to 25% of a substance having a higher molecular weight than the tetranuclear phenols, and (c) the polynuclear phenols have a UV of 254 nm as a detector. Having a weight average molecular weight Mw of 510 to 700 in terms of polystyrene obtained by gel permeation chromatography using tetrahydrofuran as an eluent, and (d) 40 to 8 of phenolic hydroxyl groups of the polynuclear phenol.
A positive resist composition is provided, wherein 0 mol% is quinonediazidesulfonic acid esterified.

Hereinafter, the present invention will be described in detail. (A) Alkali-soluble phenolic resin In the present invention, the alkali-soluble phenolic resin can be used alone or in combination of two or more. Specific examples of the alkali-soluble phenol resin include, for example, a condensation reaction product of a phenol and an aldehyde, a condensation reaction product of a phenol and a ketone,
A vinylphenol-based polymer, an isopropenylphenol-based polymer, or a hydrogenation reaction product of these phenolic resins can be used as a mixture. Specific examples of phenols used here include phenol, ortho-cresol, meta-cresol, para-cresol, 2,3-
Dimethylphenol, 2,5-dimethylphenol,
3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 2,
3,6-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 4-t-butylcatechol, 2-methoxy Phenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-t- Butyl-5-methylphenol, thymol, isothymol and the like are exemplified. Of these, ortho-cresol, meta-cresol, para-cresol,
2,3-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,5-dimethylphenol, 2,3,5-trimethylphenol, 2,
3,6-trimethylphenol is a preferred example. These compounds may be used alone or in combination of two or more.

Specific examples of aldehydes include formalin, paraformaldehyde, trioxane, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde,
p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde,
Examples thereof include o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, and terephthalaldehyde. Of these, formalin, paraformaldehyde and hydroxybenzaldehydes are preferred. These compounds may be used alone or in combination of two or more. Specific examples of ketones include acetone, methyl ethyl ketone,
Examples include diethyl ketone and diphenyl ketone.
These compounds may be used alone or in combination of two or more. These condensation reaction products can be obtained by a conventional method, for example, by reacting a phenol with an aldehyde or a ketone in the presence of an acidic catalyst.

The vinylphenol polymer is selected from a homopolymer of vinylphenol and a copolymer with a component copolymerizable with vinylphenol, and the isopropenylphenol polymer is a copolymer of isopropenylphenol. It is a homopolymer or a copolymer of isopropenylphenol with a copolymerizable component. Specific examples of components copolymerizable with vinyl phenol and isopropenyl phenol include acrylic acid, methacrylic acid, styrene,
Examples thereof include maleic anhydride, maleic imide, vinyl acetate, acrylonitrile, and derivatives thereof. The copolymer is obtained by a well-known method. The hydrogenation reaction product of the phenolic resin is obtained by a conventional method, for example, by dissolving the phenolic resin in an organic solvent and performing hydrogenation in the presence of a homogeneous or heterogeneous catalyst.

Of the above, metacresol and 2,3,5-trimethylphenol are particularly essential,
When a phenolic compound is further used and a novolak resin reacted with formaldehyde or formalin is used, excellent resist performance (especially good depth of focus) is exhibited,
In particular, it is preferable to use paracresol or 3,5-xylenol as the third phenol compound.

The alkali-soluble phenol resin used in the present invention has a weight average molecular weight in terms of polystyrene (hereinafter simply referred to as average molecular weight) determined by gel permeation chromatography using a UV 254 nm detector as a detector and tetrahydrofuran as an eluent.
Usually 2,000 to 25,000, preferably 3,500
~ 20,000. If the average molecular weight is less than 3,500, the pattern shape, resolution, and developability tend to deteriorate, and if it is less than 2,000, it is not practical. Also, 20,
If it exceeds 5,000, the pattern shape, developability and sensitivity deteriorate, and if it exceeds 25,000, it is not practical.

These alkali-soluble phenol resins can be used as those whose molecular weight and molecular weight distribution are controlled by known means. As a method for controlling the molecular weight or molecular weight distribution, the resin is crushed and solid-liquid extracted with an organic solvent having appropriate solubility, or the resin is dissolved in a good solvent and dropped into a poor solvent, or a poor solvent is used. Is added dropwise to perform solid-liquid or liquid-liquid extraction.

(B) Photosensitizer The photosensitizer used in the present invention is a quinonediazidesulfonic acid ester of a phenol, and (a) a phenol is reacted with a methylol compound obtained by reacting ortho-cresol with formaldehyde and a para-methylol compound. Polynuclear phenols obtained by reacting with cresol,
(B) The polynuclear phenol is UV2 as a detector
54 nm detector, 65 to 95% of tetranuclear phenols in an area ratio of tetrahydrofuran as an eluent, a substance having a lower molecular weight than tetranuclear phenols (including unreacted methylol compounds and unreacted phenols ) Is 5% to 25% of the substance having a higher molecular weight than the tetranuclear phenol, and (c) the polynuclear phenol is a UV254 nm detector as a detector and tetrahydrofuran as an eluent. Has a weight average molecular weight Mw of 510 to 700 in terms of polystyrene obtained by gel permeation chromatography using (d), and (d) 40 to 80 mol% of the phenolic hydroxyl groups of the polynuclear phenol are quinonediazide sulfonic acid esterified. It is a thing.

In the present invention, the polynuclear phenol serving as the mother nucleus of the photosensitive agent is prepared by reacting a methylol compound and paracresol with an acid catalyst (for example, hydrochloric acid, sulfuric acid, oxalic acid, methanesulfonic acid, paratoluenesulfonic acid, sulfonic acid type). Ion exchange resin) in the presence of an organic solvent such as methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone or an inorganic solvent such as water, or in the absence of a solvent, usually at 20 to 110 ° C. However, a single compound is rarely obtained, and usually, a state in which unreacted phenols, unreacted methylols, and polynuclear phenols to which at least one paracresol is bonded is mixed (polynuclear phenols). Mixture of body phenols). These compounds may be used as they are, or may be used after being purified by distillation, washing with a solvent, recrystallization, separation by various types of chromatography, etc., and adjusted to a predetermined mixing ratio.

The methylol compound used as a raw material may be obtained by reacting ortho-cresol with formaldehyde in the presence of an acid catalyst or by dinuclear obtained by reacting ortho-cresol with formaldehyde or ortho-cresol with formaldehyde in the presence of an acid catalyst. Body (hereinafter,
A method of obtaining orthocresol-formaldehyde binuclear) and formaldehyde by a reaction using an alkali catalyst. These reactions may be considered to be the same method as the synthesis reaction of a general novolak resin or resol resin, but by changing the ratio of each raw material, the type of catalyst, and the reaction conditions, it is possible to obtain ortho-cresol-formaldehyde dinuclear. It is possible to arbitrarily set the isomer ratio of the isomer and the obtained ratio of the monomethylol compound or dimethylol compound. In the present invention, the binuclear dimethylol form of ortho-cresol in the methylol compound obtained by the above reaction was obtained by high-performance liquid chromatography analysis using a UV254 nm detector as a detector and tetrahydrofuran as an eluent. The area ratio of the pattern is 87% or more, preferably 94% or more, and the dimethylol compound of the formula (I) is 80% or more, preferably 90% or more in the same ratio.

[0016]

Embedded image

When a raw material having a low ratio is used,
The obtained photosensitive agent is not preferred because it may deteriorate sensitivity and resolution. In the case of such a mixture, the ratio of each component to be mixed has a great influence on various resist properties.

In the present invention, the mixture of polynuclear phenols and the like used as a photosensitive material is preferably mainly composed of tetranuclear phenols, but it is not desirable that the purity of tetranuclear phenols be extremely high. Therefore, UV25 as a detector
The tetranuclear phenols were 65% in the area ratio of the pattern obtained by gel permeation chromatography using a 4 nm detector and tetrahydrofuran as an eluent.
-95%, preferably 75-90%, the total amount of substances having a lower molecular weight than tetranuclear phenols (including unreacted methylol compounds and unreacted phenols) is 10% or less, preferably 5% or less Those having 5 to 25%, preferably 5 to 15% of a substance having a higher molecular weight than tetranuclear phenols show high resist properties and good storage stability.

The main component of the tetranuclear phenols is a compound of the following formula (II).

Embedded image

The weight average molecular weight of a mixture of polynuclear phenols and the like used as a photosensitive material in the present invention (UV
254 nm detector, polystyrene-equivalent weight average molecular weight (Mw) of 5 obtained by gel permeation chromatography using tetrahydrofuran as an eluent.
A value of 10 to 700 is preferable because it exhibits particularly excellent storage stability and also has an excellent balance of resist performance. Further, the number average molecular weight Mn under the same conditions is 1.02 to
When a mixture of polynuclear phenols, which is 1.10, is used,
Particularly, excellent storage stability and resist performance can be obtained.

Further, in the present invention, the esterification rate of the phenolic hydroxyl group of a mixture of polynuclear phenols and the like also affects the resist properties. In the present invention, a phenol used as a photosensitive agent raw material in which 40 to 80 mol%, preferably 50 to 70 mol% of the phenolic hydroxyl group is quinonediazide sulfonic acid ester exhibits high resist properties. In addition, the esterification rate of the mixture defined in the present invention is handled, assuming, for convenience, that 100% is the above formula (II) in which all phenols are the main component, and means the ratio to the phenolic hydroxyl group. .

Specific examples of the esterified compound used as a photosensitizer in the present invention include 1,2-benzoquinonediazide-4-sulfonic acid ester of the above-mentioned phenol compound and 1,2-naphthoquinonediazide-4-sulfone. Acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,2-naphthoquinonediazide-6
-Sulfonic acid ester, 2,1-naphthoquinonediazide-4-sulfonic acid ester, 2,1-naphthoquinonediazide-5-sulfonic acid ester, and 2,1-naphthoquinonediazide-6-sulfonic acid ester.

The quinonediazidesulfonic acid compound is converted into a quinonediazidesulfonic acid halide, and then in a solvent such as acetone, dioxane or tetrahydrofuran, an inorganic base such as sodium carbonate, sodium hydrogencarbonate, sodium hydroxide or potassium hydroxide, or trimethylamine or triethylamine. , Tripropylamine, diisopropylamine, tributylamine, pyrrolidine, piperidine, piperazine, morpholine, pyridine, dicyclohexylamine, 1,5-diazabicyclo [4.3.0] nona-5
-Ene, 1,8-diazabicyclo [5.4.0] undec-7-ene, and the like, in the presence of an organic base such as quinonediazidesulfonic acid halide and a mixture of polynuclear phenols according to a conventional method. The quinonediazidesulfonic acid ester-based photosensitizer used in the present invention can be obtained. In the present invention, a photosensitive agent other than the above-described photosensitive agent may be used in combination.

The compounding ratio of the photosensitizer used in the present invention may be a commonly used ratio.
The lower limit is usually at least 1 part by weight, preferably at least 3 parts by weight, more preferably at least 5 parts by weight, and the upper limit is usually at most 150 parts by weight, preferably at most 100 parts by weight, more preferably at most 100 parts by weight, relative to 00 parts by weight. 80 parts by weight or less. If the blending ratio is too small, a sufficient residual film ratio cannot be obtained, resulting in deterioration of resolution. Conversely, if the blending ratio is too large, heat resistance deteriorates, which is not preferable.

(C) Phenol Compound In the present invention, a phenol compound can be added as an optional component in order to improve resist characteristics such as pattern shape, heat resistance and sensitivity. Examples of such phenol compounds include those usually used as additives in resist compositions. Specific examples include monophenols such as p-phenylphenol and p-isopropylphenol; biphenol, 4,4′-dihydroxy Diphenyl ether, 4,4'-dihydroxybenzophenone, bisphenol A (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol C (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol E (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol F (manufactured by Honshu Chemical Industry Co., Ltd.), Bisphenol AP (manufactured by Honshu Chemical), bisphenol M (manufactured by Mitsui Petrochemical), bisphenol P (manufactured by Mitsui Petrochemical), bisphenol Z (manufactured by Honshu Chemical), 1,1-bis (4- Hydroxyphenyl) cyclopentane, 9,9-bis (4-hydroxyphenyl) Yl) fluorene, 1,1-bis (5-methyl-2
-Hydroxyphenyl) methane, 3,5-dimethyl-4
Bisphenols such as -hydroxybenzylphenol; 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1-tris (4-hydroxyphenyl)
Ethane, 1,1-bis (3-methyl-4-hydroxyphenyl) -1- (4-hydroxyphenyl) methane,
1,1-bis (2,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane,
1-bis (3,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane, 2,6
-Bis (5-methyl-2-hydroxybenzyl) -4-
Methylphenol, 2,6-bis (4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3-methyl-4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3,5 -Dimethyl-4-hydroxybenzyl) -4-methylphenol, trisphenol-PA (manufactured by Honshu Chemical Industry Co., Ltd.), trisphenol-TC
(Honshu Chemical Industry Co., Ltd.) and other trisphenols;
1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-methyl-4-
Hydroxyphenyl) ethane, 1,1,3,3- (4-
Hydroxyphenyl) propane, 1,1,5,5-tetrakis (4-hydroxyphenyl) pentane, α, α,
α ', α'-tetrakis (4-hydroxyphenyl)-
3-xylene, α, α, α ′, α′-tetrakis (4-
(Hydroxyphenyl) -4-xylene, α, α, α ′,
Tetrakisphenols such as α′-tetrakis (3-methyl-4-hydroxyphenyl) -3-xylene and α, α, α ′, α′-tetrakis (3-methyl-4-hydroxyphenyl) -4-xylene Is exemplified.

The phenol compound as the component (C) is
Any one or more can be used,
In particular, when a resin having a low ratio of containing 10 or less nuclei of the alkali-soluble resin (A) is selected, good results are often obtained when such a phenol compound is used in combination. The addition amount can be arbitrarily selected.
1 part by weight or more and 40 parts by weight or less, preferably 3 parts by weight or more and 30 parts by weight or less with respect to 0 parts by weight.

The positive resist composition of the present invention is usually used by dissolving it in a solvent in order to form a resist film by coating it on a substrate. Specific examples of solvents usable in the present invention include ketones such as acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone; alcohols such as n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and cyclohexanol; Ethers such as glycol dimethyl ether, ethylene glycol diethyl ether and dioxane; alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; propyl formate, butyl formate, propyl acetate, butyl acetate, methyl propionate, and ethyl propionate; Methyl butyrate,
Ester such as ethyl butyrate, methyl lactate, ethyl lactate; cellosolve acetates such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glycol, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether Propylene glycols such as acetate and propylene glycol monobutyl ether; diethylene glycols such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether and diethylene glycol diethyl ether; halogenated hydrocarbons such as trichloroethylene; aromatics such as toluene and xylene Hydrogen like; dimethylacetamide, dimethylformamide, such as a polar solvent such as N- methyl acetamide and the like, which may be used by either singly or in combination.

In the positive resist composition of the present invention, a copolymer of styrene and acrylic acid, methacrylic acid or maleic anhydride may be added, if necessary, in order to improve developability, storage stability, heat resistance and the like. And a copolymer of an alkene and maleic anhydride, a vinyl alcohol polymer, a vinyl pyrrolidone polymer, rosin, shellac and the like. The amount of the polymer added is 0 to 100 parts by weight of the total alkali-soluble phenol resin.
It is 50 parts by weight, preferably 5 to 20 parts by weight.

The positive resist composition of the present invention may contain, if necessary, compatible additives such as a surfactant, a storage stabilizer, a sensitizer, a striation inhibitor, and a plasticizer. it can.

Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether and polyoxyethylene oleyl ether; polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenol ether Polyoxyethylene aryl ethers such as polyethylene glycol dilaurate, ethylene glycol distearate, etc .;
01, EF303, EF352 (manufactured by Shin-Akita Kasei), Megafax F171, F172, F173, F177
(Dai Nippon Ink Co., Ltd.), Florade FC430, FC4
31 (Sumitomo 3M), Asahi Guard AG71
0, Surflon S-382, SC-101, SC-1
02, SC-103, SC-104, SC-105, S
Fluorinated surfactants such as C-106 (manufactured by Asahi Glass Co., Ltd.); organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); acrylic acid or methacrylic acid (co) polymer Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Kagaku Kogyo KK). The 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 solid content of the composition.

The resist composition of the present invention generally uses an aqueous alkali solution as an alkali developing solution. Specific examples thereof include an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium silicate and ammonia; ethylamine, propyl Aqueous solutions of primary amines such as amines;
Aqueous solutions of secondary amines such as diethylamine and dipropylamine; aqueous solutions of tertiary amines such as trimethylamine and triethylamine; aqueous solutions of alcoholamines such as diethylethanolamine and triethanolamine; tetramethylammonium hydroxide, tetraethylammonium hydroxide; An aqueous solution of a quaternary ammonium hydroxide such as trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide, and trimethylhydroxyethylammonium hydroxide is exemplified. If necessary, a water-soluble organic solvent such as methanol, ethanol, propanol, and ethylene glycol, a surfactant, and a resin dissolution inhibitor may be added to the aqueous alkali solution.

A resist solution obtained by dissolving the resist composition of the present invention in a solvent is applied to the surface of a substrate such as a silicon wafer by a conventional method, and the solvent is dried and removed to form a resist film. As a coating method at this time, spin coating is particularly recommended. An exposure source used for exposure for forming a pattern on the resist film thus obtained includes an electron beam source such as an ultraviolet ray, a far ultraviolet ray, a KrF excimer laser beam, an X-ray, and an electron beam. Further, it is preferable to perform a heat treatment after the exposure (post-exposure bake) because the sensitivity, the residual film ratio, the resolution, and the heat resistance can be improved.

[0033]

The present invention will be more specifically described below with reference to synthesis examples and working examples. The parts and percentages in each example are based on weight unless otherwise specified. In addition, the measured weight average molecular weight is a UV 254 nm detector as a detector,
The polystyrene-equivalent weight average molecular weight (hereinafter, referred to as Mw) and number average molecular weight (hereinafter, referred to as Mn) in a pattern obtained by gel permeation chromatography using tetrahydrofuran as an eluent. Column is GXL2000 (60 cm) x 1 and G
XL1000 (60 cm) × 1, the flow rate of tetrahydrofuran as an eluent was 1.00 ml / min, and the column temperature was 38.
A pattern was obtained under gel permeation chromatography conditions of ° C.

(Synthesis Example 1) Synthesis of Novolak Resin A-1 A 2 liter flask equipped with a cooling pipe and a stirrer was put into a flask.
350 g of m-cresol, 350 g of p-cresol, 3
350 g of 7% formalin and 2.4 of oxalic acid dihydrate
g, and the mixture was reacted for 2 hours while maintaining the temperature at 95 to 100 ° C. Thereafter, water is distilled off at 100 to 105 ° C. over 2 hours, and while heating to 180 ° C., 10 mmHg
After reducing the pressure to remove unreacted monomers and water, the mixture was returned to room temperature and collected to obtain 450 g of novolak resin A-1. The Mw of this novolak resin was 5000.

(Synthesis Example 2) Synthesis of Novolak Resin A-2 380 g of the novolak resin obtained in Synthesis Example 1 and 350 g of ethyl cellosolve acetate were added and dissolved. A dropping funnel was attached to the flask, and while controlling the temperature at 80 to 85 ° C, 3420 g of toluene was dropped from the dropping funnel and further heated at 80 ° C for 1 hour. The mixture was gradually cooled to room temperature and left still for 1 hour. After removing the supernatant liquid of the precipitated resin by decantation, 570 g of ethyl lactate was added, and the mixture was heated to 100 ° C. at 100 mmHg to remove residual toluene, thereby obtaining an ethyl lactate solution of novolak resin A-2. Mw of the novolak resin A-2 was 9,200.

(Synthesis Example 3) Synthesis of Novolak Resin A-3 A 2 liter flask equipped with a cooling pipe and a stirrer was put into a flask.
m-cresol 318 g, p-cresol 255 g,
160 g of 2,3,5-trimethylphenol, 138 g of paraformaldehyde, and 2.5 g of oxalic acid dihydrate
And kept at 95-100 ° C for 2 hours. Thereafter, water is distilled off at 100 to 105 ° C. over 2 hours, and the temperature is further raised to 180 ° C. to 10 mmHg.
After reducing the pressure to remove unreacted monomers and water, the mixture was returned to room temperature and collected, to obtain 620 g of a novolak resin. Mw of this novolak resin was 3,900. 380 g of the novolak resin, 38 g of propylene glycol monomethyl ether acetate, and 380 g of toluene were added, and the mixture was heated and dissolved at 80 ° C. With a dropping funnel attached and controlling the temperature to 80 to 85 ° C., 3000 g of toluene
Was added dropwise, and the mixture was further heated for 1 hour. The mixture was gradually cooled to room temperature and left still for 1 hour. After removing the supernatant liquid of the precipitated resin by decantation, 60 ml of ethyl lactate was removed.
0 g was added, and the mixture was heated to 100 ° C. at 100 mmHg to remove residual toluene, thereby obtaining an ethyl lactate solution of novolak resin A-3. Mw of this novolak resin A-3 is 600
It was 0.

(Synthesis Example 4) Synthesis of Novolak Resin A-4 A 2 liter flask equipped with a cooling pipe and a stirrer was put into a flask.
420 g of m-cresol, 140 g of p-cresol,
158 g of 3,5-xylenol, 37% formalin 41
5 g, and 2.4 g of oxalic acid dihydrate, 95-1
The reaction was carried out for 40 minutes while maintaining at 00 ° C. After this, 1
Water is distilled off at 00 to 105 ° C. over 80 minutes,
While raising the temperature to 190 ° C., the pressure was reduced to 10 mmHg,
After removing unreacted monomers and water, the mixture was recovered by returning to room temperature, and 630 g of a novolak resin was obtained. Mw of this novolak resin was 3,600.

Next, the obtained novolak resin was
g, 270 g of propylene glycol monomethyl ether acetate, and 300 g of toluene were added, and the mixture was heated and dissolved at 80 ° C. Equipped with a dropping funnel, temperature 80-85 ° C
In this state, 2400 g of toluene was added dropwise, and the mixture was further heated for 1 hour. The mixture was gradually cooled to room temperature and left still for 1 hour. After removing the supernatant liquid of the precipitated resin by decantation, 500 g of ethyl lactate was added, and
The mixture was heated to 100 ° C. at 00 mmHg to remove residual toluene, thereby obtaining an ethyl lactate solution of novolak resin A-4. Mw of this novolak resin A-4 was 6,200.

(Synthesis Example 5) Synthesis of Novolak Resin A-5 A 2 liter flask equipped with a cooling pipe and a stirrer was put into a flask.
292 g of m-cresol, 3,5-xylenol 110
g, 2,3,5-trimethylphenol 112 g, 37
% Formalin 390 g and oxalic acid dihydrate 1.7 g
And kept at 95-100 ° C for 2 hours. Thereafter, water is distilled off at 100 to 105 ° C. over 2 hours, and the temperature is further increased to 190 ° C. by 10 mmHg.
After reducing the pressure to remove unreacted monomers and water, the mixture was returned to room temperature and collected, to obtain 560 g of a novolak resin. Mw of this novolak resin was 3,400.

Next, the obtained novolak resin was mixed with 300
g, 30 g of propylene glycol monomethyl ether acetate, and 300 g of toluene were added, and the mixture was heated and dissolved at 80 ° C. With a dropping funnel attached, 2400 g of toluene was added dropwise while controlling the temperature at 80 to 85 ° C, and the mixture was further heated for 1 hour. The mixture was gradually cooled to room temperature and left still for 1 hour. After removing the supernatant liquid of the precipitated resin by decantation, 600 g of ethyl lactate was added, and
The mixture was heated to 100 ° C. at 0 mmHg to remove residual toluene, thereby obtaining a solution of novolak resin A-5 in ethyl lactate. Mw of this novolak resin A-5 was 4,300.

(Synthesis Examples 6 to 9, Synthesis of Photosensitive Agents B-1 to B-4) As a methylol compound, a total of a dimethylol compound of ortho-cresol-formaldehyde binuclear was used, a UV254 nm detector was used as a detector, and tetrahydrofuran was used as an eluent. The area ratio of the pattern obtained by gel permeation chromatography analysis using
%, And the methylol compound (1) containing the dimethylol compound of the formula (I) in an equal ratio of 94% was used as a raw material. In a flask, add 150 g of paracresol and 0.7 hydrochloric acid.
0 g was added, and while maintaining the temperature at 60 ° C., 20 g of the methylol compound (1) was dropped from the dropping funnel over 30 minutes, and the mixture was further reacted for 1 hour. Thereafter, water was distilled off at 100 ° C. over 30 minutes, and further distilled at 170 ° C. under reduced pressure to remove unreacted paracresol. After returning to room temperature, 300 g of methyl isobutyl ketone was added and dissolved, washed with 0.5% aqueous solution of tetramethylammonium hydroxide and 1% hydrochloric acid, and then washed with ion-exchanged water. The solvent was removed from the organic layer by distillation under reduced pressure and a vacuum dryer to obtain 39.6 g of polynuclear phenol compound b-1. UV2 as detector
As a result of analysis by gel permeation chromatography using a 54 nm detector and tetrahydrofuran as an eluent, 4% (area ratio) of compounds having a lower molecular weight than tetranuclear phenols in the polynuclear phenol compound b-1 were tetranuclear. 82% phenols, 1 compound higher than tetranuclear
4%. When the detector was similarly analyzed using a refractive index system, the area ratio was the same.

9.4 g of the polynuclear phenols b-1 thus obtained and 15.0 g of 1,2-naphthoquinonediazidosulfonic acid chloride (100% of which is of the formula (I)
Assuming that the compound is a tetranuclear phenol compound represented by I), 70 mol% of its hydroxyl groups) is added to the flask, and
Dissolved in 220 g of acetone. 6.8 g of triethylamine (1,2-naphthoquinonediazide-5-sulfonic acid chloride 1.2
(Equivalent amount) was added dropwise over 30 minutes, and the reaction was completed by maintaining at this temperature for 4 hours. The precipitated salt was separated by filtration and poured into 2400 g of a 0.2% oxalic acid aqueous solution. The precipitated solid was filtered, washed with ion-exchanged water, and dried under vacuum to obtain a naphthoquinonediazidesulfonic acid ester-based photosensitizer B-1 having an esterification rate of 70% in 20.1%.
g was obtained.

By the same method as above, the charge ratio of 1,2-naphthoquinonediazide-5-sulfonic acid chloride to the polynuclear phenol compound (1) and the amount of triethylamine were changed, and the esterification ratio was 65% and 60%. %,
50% of photosensitive agents B-2, B-3 and B-4 were obtained.

(Synthesis Example 10) Synthesis of Photosensitive Agent B-5 A UV 254 nm detector was used in the same manner as in Synthesis Example 6, except that 20.0 g of the methylol compound (1) and 113 g of paracresol were used. The area ratio determined by gel permeation chromatography using tetrahydrofuran as an eluent was 4% of a compound having a lower molecular weight than tetranuclear phenols and 76% of tetranuclear phenols.
%, A polynuclear phenol compound b-2 containing 20% of a higher molecular compound than a tetranuclear compound was synthesized. When the detector was similarly analyzed using a refractive index system, the area ratio was the same. Using this polynuclear phenol b-2, a photosensitive agent B-5 having an esterification rate of 75% was obtained in the same manner as in Synthesis Example 6.

(Synthesis Example 11) Synthesis of Photosensitizer B-6 A pattern obtained by gel permeation chromatography analysis of a methylol compound and cresol using a UV254 nm detector as a detector and tetrahydrofuran as an eluent, respectively. 20. The methylol compound (2) in which the dimethylol compound of the binuclear orthocresol-formaldehyde is 98% and the dimethylol compound of the formula (I) is 96% in the area ratio of 20.
By the same method as in Synthesis Example 6 except that 0 g and 188 g of paracresol were used, the same area ratio was 2% of a compound having a lower molecular weight than tetranuclear phenols, and 90% of tetranuclear phenols was 90%.
%, A polynuclear phenol compound b-3 containing 8% of a higher molecular compound than a tetranuclear compound was synthesized. When the detector was similarly analyzed using a refractive index system, the area ratio was the same. Using this polynuclear phenol b-3, a photosensitive agent B having an esterification rate of 65% was obtained in the same manner as in Synthesis Example 6.
-6 was obtained.

(Synthesis Example 12) Synthesis of Photosensitive Agent B-7 A pattern obtained by gel permeation chromatography analysis of a methylol compound and cresol using a UV254 nm detector as a detector and tetrahydrofuran as an eluent, respectively. The methylol compound (3) having 100% of the dimethylol compound of the orthonucleoform-formaldehyde binuclear compound and 99% of the dimethylol compound of the formula (I) in an area ratio of 2
Except that 0.0 g and 225 g of orthocresol were used,
The compound was synthesized in the same manner as in Synthesis Example 6, and further recrystallized with a mixed solvent of methanol / water = 1/4 to obtain the compound of the following formula (I
A polynuclear phenol compound b-4 containing a tetranuclear phenol compound represented by II) as a main component was obtained.

[0047]

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The compound b-4 was treated with UV2 as a detector.
The area ratio of the pattern obtained by gel permeation chromatography analysis using a 54 nm detector and tetrahydrofuran as an eluent is 0% of a compound having a lower molecular weight than tetranuclear phenols, and 98% of tetranuclear phenols is 98%.
% Of the compound having a higher molecular weight than the tetranuclear compound, and 97% of the compound of the formula (III). Using this polynuclear phenol b-4, in the same manner as in Synthesis Example 6,
Photosensitive agent B-7 having an esterification rate of 60% was obtained. The esterification ratio shown here means that 60% of the hydroxyl groups were substituted, assuming that 100% of the polynuclear phenol b-4 was the compound represented by the formula (III).

Synthesis Example 13 Synthesis of Photosensitizer B-8 Instead of the polynuclear phenol compound, 2,3,4,4′-
Photosensitizer B-8 having an esterification rate of 75% was obtained in the same manner as in Synthesis Example 5 using tetrahydroxybenzophenone.

The amount (%) of phenols having a lower molecular weight than tetranuclear phenols in the mixture of polynuclear phenols, etc., which are raw materials of the respective photosensitive agents obtained in the above synthesis examples (in the table, "low molecular weight"). The amount (%) of tetranuclear phenols in the mixture of polynuclear phenols and the like ("tetranuclear" in the table), a phenol having a higher molecular weight than the tetranuclear phenols in the mixture of polynuclear phenols and the like as the raw material The amounts (%) of the class ("polymer" in the table) and the esterification ratio are summarized in Table 1.

[0051]

[Table 1]

(Evaluation) The resist evaluation method in the following Examples and Comparative Examples is as follows. All the resist evaluations were performed on a silicon wafer. (1) Sensitivity A value (unit: msec) representing the amount of exposure energy that can form a 1: 1 line & space of 0.50 μm according to design dimensions. (2) Resolution Limit resolution (unit: μm) under the above exposure conditions. (3) Residual film ratio The ratio (%) of the resist film thickness before and after development of a portion where a pattern is not formed on the wafer. (4) Pattern Shape The wafer on which the resist pattern was formed was cut from the direction perpendicular to the line pattern, and the result of observation with an electron microscope from the cross-sectional direction of the pattern was shown. Pattern sidewalls were raised at an angle of 80 ° or more with respect to the substrate, and those without film reduction were judged to be good. Those less than 80 degrees are described as "taper" in the table. In the table, the occurrence of scum was described in the table as "scum", and the side wall defect due to the standing wave (stepped shape was confirmed) was described as "standing wave" in the table. (5) Exposure margin The relationship between the exposure time and the pattern dimensions measured for sensitivity is graphed to determine the width of the exposure time that can be maintained within ± 5% of the design dimension variation, and this width is divided by the sensitivity. It is. (6) Depth of focus (1m line and space sensitivity of 0.50μm) Focus fluctuation width (μm) that can maintain the fluctuation width of the pattern dimension when changing the focus of the stepper within ± 5% of the design dimension Represents

(7) Increase in Fine Particles Regarding the presence or absence of increase in fine particles in the resist solution stored at 23 ° C. and 35 ° C., a resist was applied to 4-inch bare silicon to a thickness of 1.07 μm, and a wafer monitor WM manufactured by Topcon Corporation was used. 0.2μ in the resist film using -3
m or more of the fine particles were measured. Immediately after preparing the resist solution (confirm that the number of fine particles is 20 or less)
The period until the number increases to 200 or more is expressed in days.

Examples 1 to 6 and Comparative Examples 1 to 5 The amounts of solvents were adjusted so that the resist solutions having the compositions shown in Table 2 could be applied to a film thickness of 1.07 to 0.76 μm. These solutions were filtered through a 0.1 μm Teflon filter (polytetrafluoroethylene filter) to prepare a resist solution.

After the resist solution was coated on a silicon wafer by a coater, prebaking was performed at 90 ° C. for 90 seconds. In Examples 1 to 4, a 1.07 μm-thick resist film was obtained. Is 0.76
A μm resist film was formed. This wafer was placed in an i-line stepper NSR1755i7A (Nikon Corporation; NA = 0.5).
After performing exposure while varying the exposure time using 0) and a test reticle, post exposure baking (post exposure baking) was performed at 110 ° C. for 60 seconds. Next, a positive pattern was formed by developing with a 2.38% aqueous solution of tetramethylammonium hydroxide by a paddle method at 23 ° C. for 1 minute. The wafer was taken out and observed with an electron microscope, and the sensitivity, resolution, remaining film ratio, pattern shape, exposure margin, and depth of focus were observed, and storage stability was confirmed as the degree of increase in the number of fine particles. Table 2 shows the results.

[0056]

[Table 2]

Description of abbreviations in Table 2: B-9 = 1, synthesized in the same manner as in Synthesis Example 7 using phenols obtained by reacting ortho-cresol and para-cresol with 37% formalin according to a conventional method. 2-Naphthoquinonediazidosulfonic acid ester B-10 = Synthesis example 7 using a phenol containing a tetranuclear compound obtained by reacting a methylol compound represented by the following formula (IV) with 2,5-xylenol 1,2-naphthoquinonediazidosulfonic acid ester synthesized by the same method as described above

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B-11 = Synthesized in the same manner as in Synthesis Example 7 using a phenol containing a tetranuclear compound obtained by reacting the methylol compound represented by the formula (IV) with orthocresol. 1,2-naphthoquinonediazidosulfonic acid ester

C-1 = trisphenol PA (manufactured by Honshu Chemical Industry Co., Ltd.) C-2 = 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane C- 3 = Bisphenol F (Honshu Chemical Industry Co., Ltd.) C-4 = Bisphenol Z (Honshu Chemical Industry Co., Ltd.)

From the results, it was found that the use of the photosensitive agent of the present invention improved various resist characteristics such as sensitivity, residual film ratio, resolution, pattern shape, depth of focus, and exposure margin, and was excellent in storage stability.

[0061]

As described above, according to the present invention, it is suitable as a positive resist for fine processing of 1 .mu.m or less which is excellent in various resist characteristics and also excellent in storage stability.

Claims (1)

[Claims] (A) an alkali-soluble phenolic resin,
And (B) a quinonediazide sulfonic acid ester-based photosensitizer of a phenol, wherein (B) the photosensitizer is (a) the phenol is:
Polynuclear phenols obtained by reacting a methylol compound obtained by reacting orthocresol with formaldehyde and paracresol, and (b) the polynuclear phenol is a UV254 nm detector as a detector, an eluent In the area ratio of the pattern obtained by gel permeation chromatography using tetrahydrofuran as the
The total amount of substances having a lower molecular weight than nucleated phenols (including unreacted methylol compounds and unreacted phenols) is 10% or less, and a mixture of substances having a higher molecular weight than tetranuclear phenols is 5 to 25%. (C) the polynuclear phenol has a weight average molecular weight Mw of 510 to 700 in terms of polystyrene obtained by gel permeation chromatography using a UV 254 nm detector as a detector and tetrahydrofuran as an eluent;
(D) A positive resist composition characterized in that 40 to 80 mol% of the phenolic hydroxyl groups of the polynuclear phenol are quinonediazidesulfonic acid esterified.