JPH0990625A - Positive resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the sensitivity, film endurance, resolution, pattern forms, exposure margins, and focus margins by using specified phenols. SOLUTION: The positive resist composition contains an alkali-soluble phenol resin and a quinonediazidosulfonate type photosensitive agent and the phenols having the following structural units represented by the formula in which each of R<1> and R<2> is, independently, H atom or an optionally substituted alkyl optionally substituted aryl group. The alkali-soluble phenol resin can be exemplified by the condensation products of the phenolic compounds with aldehydes and ketones, vinylphenol polymers, isopropenylphenol polymers, and the hydrogenation products of these phenol resins, and their mixtures, and the phenol compounds can be embodied by phenol, o-cresol, m-cresol, p-cresol, p-cresol, 2,3-dimethylphenol, and the like.

Description

Detailed Description of the Invention

[0002]

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.

[0003]

2. Description of the Related Art As a resist composition for forming a semiconductor device, a positive resist composition has recently become mainstream. This is because the negative resist composition has high sensitivity, but has a difficulty in resolution because of swelling because an organic solvent is used for development, and the positive resist composition has excellent resolution. Therefore, it is considered that it is possible to 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 novolac resin and a quinonediadisulfonic 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 exposure machine, and it has become possible to form a fine pattern of 1 μm or less.

However, conventional positive resist compositions have not always been satisfactory in terms of various characteristics such as sensitivity, residual film rate, 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 point of view, it has been proposed to use various phenols as additives (Japanese Patent Laid-Open No. Hei 3).
-200252, JP-A-4-122938, JP-A-5-127374, JP-A-5-232697). However, the positive resist compositions specifically disclosed in these documents have somewhat insufficient resist properties such as sensitivity, resolution and residual film rate, and further improvement is required.

[0005]

Under such a conventional technique, the inventors of the present invention have diligently studied to solve the above-mentioned problems, and as a result, it has been found that the above object can be achieved by using a specific phenol. The present invention has been completed and the present invention has been completed.

[0006]

Thus, according to the present invention, an alkali-soluble phenol resin, a quinonediazide sulfonic acid ester type photosensitizer and a phenol having a structural unit represented by the following general formula (I) are contained. A featured positive resist composition is provided.

Embedded image (In the formula, R ^{1 and} R ² are each independently a hydrogen atom, a substitutable alkyl group, or a substitutable aryl group.)

The present invention will be described in detail below. (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 compound and an aldehyde, a condensation reaction product of a phenol compound and a ketone, a vinylphenol polymer, an isopropenylphenol heavy polymer. In combination, hydrogenation reaction products of these phenol resins and the like can be mixed and used.
Specific examples of the phenol compound used here include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol and 3,5-. Dimethylphenol, 2,4-dimethylphenol, 2,
6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-
Butylphenol, 3-t-butylphenol, 4-t
-Butylphenol, 2-methylresorcinol, 4-
Methylresorcinol, 5-methylresorcinol, 4
-T-butylcatechol, 2-methoxyphenol, 3
-Methoxyphenol, 2-propylphenol, 3-
Propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol,
Examples include 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, thymol and isothymol. Of these, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,3,5- Trimethylphenol and 3,4,5-trimethylphenol are preferred examples. 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, acetaldehyde and benzaldehyde are preferable. These compounds may be used alone or in combination of two or more.
Specific examples of the ketones include acetone, methyl ethyl ketone, diethyl ketone, diphenyl ketone, acetophenone and the like. 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-based polymer is selected from a homopolymer of vinylphenol and a copolymer with a component copolymerizable with vinylphenol, and the isopropenylphenol-based 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.

The GP of the alkali-soluble phenol resin used in the present invention using a UV 254 nm detector
The polystyrene reduced weight average molecular weight (hereinafter, simply referred to as weight average molecular weight) according to the C pattern varies depending on the type of resin and the production method, but is usually 1,000 to 25,000, and preferably 2,500 to 12,000. If the average molecular weight is less than 1,000, the pattern shape, resolution and heat resistance tend to deteriorate. On the other hand, if it exceeds 25,000, the pattern shape, developability, and sensitivity deteriorate, which 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 polyhydroxy compound.
Not all hydroxyl groups in the molecule need be esterified, but may be partially esterified. Specific examples of the esterified compound used as a photosensitizer include:
1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, and 1,2-benzoic acid ester of these polyhydroxy compounds
Naphthoquinonediazide-6-sulfonic acid ester, 2,
1-naphthoquinonediazide-4-sulfonic acid ester,
Examples thereof include 2,1-naphthoquinonediazide-5-sulfonic acid ester and 2,1-naphthoquinonediazide-6-sulfonic acid ester.

The quinonediazidesulfonic acid ester of the polyhydroxy compound is prepared by converting the quinonediazidesulfonic acid compound into a quinonediazidesulfonic acid halide according to a conventional method, and then adding sodium carbonate, sodium hydrogencarbonate, sodium hydroxide in a solvent such as acetone, dioxane or tetrahydrofuran. Or an inorganic base such as potassium hydroxide, or trimethylamine, triethylamine, tripropylamine, diisopropylamine, tributylamine,
In the presence of an organic base such as pyrrolidine, piperidine, piperazine, morpholine, pyridine, dicyclohexylamine,
By reacting a quinonediazidesulfonic acid halide with a polyhydroxy compound, the quinonediazidesulfonic acid ester-based photosensitizer used in the present invention can be obtained.

The hydroxy compound used here is a known compound having a phenol group, and specific examples thereof include 2,3,4-trihydroxybenzophenone,
2,4,4'-trihydroxybenzophenone, 2,
3,4,4'-tetrahydroxybenzophenone, 2,
4,2 ', 4'-tetrahydroxybenzophenone,
Polyhydroxybenzophenones such as 2,3,4,2 ', 4'-pentahydroxybenzophenone; gallic esters such as methyl gallate, ethyl gallate and propyl gallate; 2,2-bis (4-hydroxyphenyl )
Polyhydroxybisphenylalkanes such as propane and 2,2-bis (2,4-dihydroxyphenyl) propane; tris (4-hydroxyphenyl) methane,
1,1-tris (4-hydroxy-3-methylphenyl) ethane, 1,1,1-tris (4-hydroxy-3
-Methylphenyl) ethane, 1,1,1-tris (4-
Hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) -1- (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-methylphenyl) -2-hydroxy-4-methoxy Polyhydroxytrisphenylalkanes such as phenylmethane;
1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-methyl-4-hydroxyphenyl) ethane, 1,1,3,3-
Polyhydroxytetrakisphenylalkanes such as tetrakis (4-hydroxyphenyl) propane; α, α,
α ', α'-tetrakis (4-hydroxyphenyl)-
3-xylene, α, α, α ′, α′-tetrakis (4-
(Hydroxyphenyl) -4-xylene, α, α, α ′,
polyhydroxytetrakiphenylxylenes such as α'-tetrakis (3-methyl-4-hydroxyphenyl) -3-xylene; 2,6-bis (2,4-dihydroxybenzyl) -p-cresol, 2,6- Bis (2,4-dihydroxy-3-methylbenzyl) -p-cresol,
4,6-bis (4-hydroxybenzyl) resorcinol,
4,6-bis (4-hydroxy-3-methylbenzyl)
Resorcinol, 4,6-bis (4-hydroxybenzyl)
Trimer of phenols such as 2-methylresorcin, 4,6-bis (4-hydroxy-3-methylbenzyl) -2-methylresorcin and formalin, phenolic compound represented by the following general formula (II) and formalin And tetramers, and novolak resins.

Embedded image (In the formula, R ³ and R ⁴ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{5 to} R ⁸ are independently an alkyl group having 1 to 4 carbon atoms.)

In the photosensitive agent used in the present invention, the ratio of esterification of the quinonediazidesulfonic acid compound to these polyhydroxy compounds (average esterification ratio)
Is not particularly limited, but the lower limit is usually 20%, preferably 30% as the mol% of the quinonediazide sulfonic acid compound relative to the hydroxyl group of the polyhydroxy compound, and the upper limit is usually 100%, preferably 95%. If the esterification ratio is too low, the pattern shape and the resolution may be deteriorated. If the esterification ratio is too high, the sensitivity may be lowered.

The photosensitizers used in the present invention may be used alone or in admixture of two or more. The amount of the photosensitizer is usually 1 to 100 parts by weight, based on 100 parts by weight of the alkali-soluble phenol resin (a).
It is preferably 5 to 60 parts by weight. If the amount is less than 1 part by weight, it becomes difficult to form a pattern. If the amount exceeds 100 parts by weight, the sensitivity is lowered and the development residue tends to occur.

(C) Phenols The phenols used in the present invention are those having a structural unit represented by the above formula (I) (hereinafter sometimes referred to as phenols (c)), and are commercially available. The following formula (III)

Embedded image It can be obtained by condensation polymerization of the compound represented by and an aldehyde or a ketone as a raw material of the alkali-soluble resin in the presence of an acidic catalyst.

In the formula (I), specific examples of R ^{1 and} R ² are:
Hydrogen atom; methyl group, ethyl group, 2-hydroxyethyl group, n-propyl group, isopropyl group, 3-hydroxypropyl group, n-butyl group, 3-chlorobutyl group, s-
Butyl group, t-butyl group, isobutyl group, n-pentyl group, t-amyl group, isopentyl group, cyclopentyl group, n-hexyl group, isohexyl group, cyclohexyl group, cycloheptyl group, 1-methylpentyl group, 2- Substituted alkyl group having 1 to 8 carbon atoms such as methylcyclopentyl group and 1-ethylcyclohexyl group; phenyl group, 4
-Hydroxyphenyl group, 4-methylphenyl group, 3-
Methoxyphenyl group, 4-chlorophenyl group, 2,4-
And a substituted aryl group such as dimethylphenyl group, naphthyl group, 2-hydroxynaphthalene, and 4-hydroxynaphthalene. As described above, in the present invention, the alkyl group may be linear, branched or cyclic, and as the substituent of the alkyl group and the aryl group, a halogen atom, an alkyl group having about 1 to 4 carbon atoms, a hydroxyl group ,
Preferable examples are alkoxy groups having about 1 to 4 carbon atoms. Among these, a hydrogen atom, a methyl group, a phenyl group and the like are preferable examples because of easy availability of raw materials and easiness of synthesis. Therefore, preferable examples of aldehydes or ketones as raw materials of the phenols (c) include formalin, paraformaldehyde, acetone, benzophenone, salicylaldehyde, p-hydroxybenzaldehyde and the like.

When the total amount of aldehydes and / or ketones is 1 mol, the compound represented by the formula (III) is usually 0.6 to 4 mol, preferably 1.0 mol to 2.0.
React the moles.

The weight average molecular weight of the phenol (c) used in the present invention is usually 2,000 or less, preferably 400.
˜2,000, particularly preferably 500 to 1500. Further, the GPC pattern area ratio of the phenols (c) used in the present invention detected by UV254 nm is 30% or more, preferably 25% or more when the structural unit represented by the formula (I) is 1 or more. In addition, the unreacted compound represented by the formula (III) may be confirmed by the GPC pattern in the phenols (c), and is represented by the unreacted formula (III). The ratio of the compound contained in the phenols (c) is UV2.
The GPC pattern area ratio detected at 54 nm is less than 30%, preferably 5% or more and less than 30%, more preferably 1
It is 0% or more and less than 25%. Unreacted formula (III)
If the compound represented by (3) does not exist at all, the sensitivity tends to decrease, and conversely, if it is too large, the resolution decreases, and a good pattern shape may not be obtained.

Even if the unreacted compound represented by the formula (III) is less than the above-mentioned range, a compound represented by the formula (III) is added separately to obtain the compound represented by the formula (III).
The ratio of the compound represented by can be adjusted within the above range. The molecular weight and the molecular weight distribution can be controlled by a synthetic method or a known means (liquid-liquid extraction, etc.).

A particularly preferred specific example of the phenol (c) used in the present invention is the following formula (I-1) which is a condensate of the compound of formula (III) and formalin or paraformaldehyde.

Embedded image The following formula (I-2), which is a condensate of the compound of formula (III) and acetone

[Chemical 6] The following formula (I-3), which is a condensation product of the compound of formula (III) and benzophenone

[Chemical 7] The following formula (I-4) which is a condensate of the compound of formula (III) and salicylaldehyde

Embedded image The following formula (I-5), which is a condensate of the compound of formula (III) and p-hydroxybenzaldehyde

Embedded image And the like.

In the present invention, phenols other than general formula (I) (hereinafter sometimes referred to as other phenols) may be used in combination, and high resist properties may be obtained in some cases. Specific examples of other phenols that can be used in combination include p-phenylphenol,
Monophenols such as p-isopropylphenol; biphenol, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybenzophenone, bisphenol A (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol C (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol E (Made by Honshu Chemical Industry Co., Ltd.), bisphenol F (made by Honshu Chemical Industry Co., Ltd.), bisphenol AP (made by Honshu Chemical Industry Co., Ltd.), bisphenol M
(Mitsui Petrochemical Co., Ltd.), bisphenol P (Mitsui Petrochemical Co., Ltd.), bisphenol Z (Honshu Chemical Co., Ltd.), 1,1-bis (4-hydroxyphenyl) cyclopentane, 9,9-bis ( Bisphenols such as 4-hydroxyphenyl) fluorene, 1,1-bis (5-methyl-2-hydroxyphenyl) methane and 3,5-dimethyl-4-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, 1,1-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)
Trisphenols such as -4-methylphenol, trisphenol-PA (manufactured by Honshu Chemical Industry Co., Ltd.) and trisphenol-TC (manufactured by Honshu Chemical Industry Co., Ltd.); 1,1,2,2-
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 ′, α′-tetrakis (3-methyl -4-hydroxyphenyl) -3-
Examples include tetrakisphenols such as xylene, α, α, α ′, α′-tetrakis (3-methyl-4-hydroxyphenyl) -4-xylene. Among them, bisphenols, trisphenols, tetrakisphenols and the like are particularly preferable examples.

The amount of these (C) phenols added is
The total amount of phenols (that is, the amount of phenols (c) in the case of phenols (c) alone) may vary somewhat depending on the composition of the alkali-soluble phenol resin, the molecular weight, the molecular weight distribution, and the types and amounts of other additives. , Phenols (c)
When used together with other phenols, the upper limit of the total amount of phenols (c) and other phenols is 100 parts by weight of the alkali-soluble phenol resin, and the upper limit is usually 1
The amount is 00 parts by weight or less, preferably 60 parts by weight or less, and the lower limit is usually 3 parts by weight or more, preferably 5 parts by weight or more. When the phenols (c) and other phenols are used in combination, the ratio of the phenols (c) to the other phenols is 1: 5 or less by weight, preferably 1: 1 or less, more preferably 1: 1. It is 0.8 or less.

The positive resist composition of the present invention is usually used by dissolving it in a solvent to apply it to a substrate to form a resist film. 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.

The positive resist composition of the present invention may optionally contain a copolymer of styrene and acrylic acid, methacrylic acid or maleic anhydride in order to improve developability, storage stability, heat resistance and the like. , A copolymer of an alkene and maleic anhydride, a vinyl alcohol polymer, a vinylpyrrolidone polymer, rosin, shellac and the like can be added. 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 optionally contain compatible additives such as a surfactant, a storage stabilizer, a sensitizer, an anti-striation agent 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 octylphenyl ether, polyoxyethylene nonylphenol ether, and the like. Oxyethylene aryl ethers; polyethylene glycol dialkyl esters such as polyethylene glycol dilaurate and ethylene glycol distearate; Ftop EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.), Megafax F171, F172, F173,
F177 (manufactured by Dainippon Ink and Chemicals), Florard FC43
0, FC431 (Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-10.
1, SC-102, SC-103, SC-104, SC
-105, SC-106 (manufactured by Asahi Glass Co., Ltd.) and the like; organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); acrylic acid-based or methacrylic acid-based (co) polymer polyflow No. 75, no. 95 (manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.). 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.

In the resist composition of the present invention, an alkaline aqueous solution is usually used as an alkaline developing solution. Specific examples thereof include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate and ammonia; ethylamine and 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 film can be formed by applying a resist solution prepared by dissolving the resist composition of the present invention in a solvent onto the surface of a substrate such as a silicon wafer by a conventional method and then removing the solvent by drying. 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 (post-exposure bake) after the exposure because the sensitivity can be improved and stabilized.

The preferred embodiments of the present invention are shown below, but the present invention is not limited thereto. In a positive resist composition containing an alkali-soluble phenol resin, a quinonediazide sulfonic acid ester-based photosensitizer, and a phenol, a phenol having a structural unit represented by the general formula (I) and a phenol other than the phenol A positive resist composition containing a phenol. A positive resist composition in which the phenols other than the phenols having the structural unit represented by formula (I) are trisphenols and tetrakisphenols. The positive resist composition as described above, wherein the phenols having the structural unit represented by the formula (I) and the phenols other than the phenols are used in a ratio of 1: 5 or less by weight. In a positive resist composition containing an alkali-soluble phenol resin, a quinonediazide sulfonic acid ester-based photosensitizer, and phenols, the phenols are represented by the above formula (III) and spirobiindanediols and aldehydes or ketones. A positive resist composition containing a phenol having a structural unit represented by the above formula (I) obtained by a condensation polymerization reaction. A positive resist composition further containing other phenols not containing the phenol having the structural unit represented by the formula (I).

[0032]

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 measured by GPC using a UV 254 nm detector.
It is the polystyrene reduced weight average molecular weight in the pattern.

Reference Example 1 Synthesis of Novolac Resin 1A In a 2 liter flask equipped with a cooling tube and a stirrer,
m-cresol 335 g, p-cresol 411 g, 3
6% formalin 394 g and oxalic acid dihydrate 2.45
g, and use the mantle heater as a heat source for 95-100
The reaction was carried out for 35 minutes while maintaining the temperature at ℃. Then, the cooling pipe was replaced with a distillation pipe, water was distilled off at 100 to 105 ° C. for 100 minutes, and then the temperature was started to increase. When 170 ° C. was reached, the pressure was reduced to 10 mmHg, and the temperature was further increased to 190 ° C. To remove unreacted monomer and water. Then, the temperature was returned to room temperature and recovered to obtain 554 g of novolac resin A-1. The weight average molecular weight (Mw) of the novolac resin 1A was measured and found to be 5,200. The softening point of this resin measured by the ring and ball method is 145 ° C.
Met.

Reference Example 2 Acquisition of Novolac Resin 1A-2 300 g of the novolak resin A-1 obtained in Synthesis Example 1 was placed in a 5 liter capacity flask equipped with a dropping funnel, a stirrer and a thermometer and propylene glycol monomethyl ether. Add 200 g of acetate and 80 g of toluene, and add 8
It was heated to 5 ° C. and dissolved by stirring. While maintaining the temperature at 80 to 85 ° C., 2800 g of toluene was dropped from the dropping funnel over 15 minutes, and then the temperature was kept for 10 minutes. Then, the mixture was allowed to cool to 30 ° C. and the precipitated resin supernatant was removed by decantation.
50 g was added, and the residual toluene was removed by heating at 100 ° C. at 100 mmHg to obtain an ethyl lactate solution of novolak resin 1A-2. The weight average molecular weight (Mw) of the novolac resin 1A-2 was 7,100.

Reference Example 3 Synthesis of Novolac Resin 2A-1 In a 2 liter flask equipped with a cooling tube and a stirrer,
199 g of m-cresol, 139 g of p-cresol,
160 g of 2,3,5-trimethylphenol, 92.4 g of 92% formaldehyde and 1.7 of oxalic acid dihydrate
90g to 10g with mantle heater as heat source
The reaction was carried out for 100 minutes while maintaining the temperature at 0 ° C. Then, the cooling tube was replaced with a distillation tube, water was distilled off at 100 to 105 ° C for 30 minutes, and then the temperature was started to increase. When the temperature reached 170 ° C, the pressure was reduced to 10 mmHg and the temperature was further increased to 198 ° C. To remove unreacted monomer and water. After this, the temperature is returned to room temperature and recovered, and novolak resin 2A-1 428 g
I got The weight average molecular weight (Mw) of this novolak resin 2A-1 was measured to be 3,900. The softening point of this resin measured by the ring and ball method is 1
It was 45 ° C.

(Reference Example 4) Acquisition of Novolac Resin 2A-2 The same method as in Synthesis Example 2 except that the resin 2A-1 obtained in Synthesis Example 3 was used as the novolac resin and the solvent in which it was dissolved was 3000 g of toluene. By novolac resin 2
An ethyl lactate solution of A-2 was obtained. Novolac resin 2A-
When the weight average molecular weight (Mw) of 2 was measured, it was 5,3
It was 00.

Reference Example 5 Synthesis of Photosensitizer As a polyhydroxy compound, a compound of the general formula (IV)

Embedded image A 10% solution of 1,2-naphthoquinonediazide-5-sulfonic acid chloride (amount: mol% corresponding to an esterification rate of 70%) as a quinonediazide sulfonic acid compound in acetone is used. And Two
While controlling the temperature at 0 to 25 ° C, 1.2 equivalents of triethylamine of 1,2-naphthoquinonediazide-5-sulfonic acid chloride was added dropwise over 30 minutes, and the reaction temperature was maintained for 2 hours for reaction. Was completed. The precipitated salt was separated by filtration and put into a 0.2% aqueous solution of oxalic acid in an amount 10 times as much as the reaction solution. The precipitated solid content was filtered, washed with ion-exchanged water, and dried to obtain a quinonediazidesulfonic acid ester-based photosensitizer.

(Synthesis Example 1) Synthesis of 1C of phenols In a flask of 1 liter capacity equipped with a cooling tube, a stirrer and a thermometer, the spirobiindanediol represented by the above formula (III) (Mitsui Toatsu Chemical Co., Ltd.) Product name "S
I ") 92.4 g (0.30 mol), 92% paraformaldehyde 4.89 g (0.15 mol), methanesulfonic acid 0.216 g (0.00225 mol) and dioxane 220 g were added and dissolved. Using a mantle heater as a heat source, the reaction was carried out for 15 hours while maintaining the temperature at 100 ° C. The reaction solution was cooled to 40 ° C., and 2200 g of a 0.05% tetramethylammonium hydroxide aqueous solution
It was thrown in and the resin was precipitated. The precipitated resin was filtered off, washed with ion-exchanged water, and vacuum dried at 130 ° C. and 10 mmHg to obtain 84.5 g of phenol 1C. This compound 1C has a weight average molecular weight (Mw) of 710, and one having 1 or more structural units represented by the formula (I) has a GPC area ratio of 47% (unreacted spirobiindanediol has a GPC area of The ratio was 53%).

(Synthesis Example 2) Synthesis of Phenol 2C A spirobiindanediol represented by the above formula (III) (Mitsui Toatsu Chemical Co., Ltd.) was placed in a flask having a capacity of 1 liter equipped with a cooling tube, a stirrer and a thermometer. Product name "S
I ") 92.4 g (0.30 mol), 92% paraformaldehyde 6.52 g (0.20 mol), methanesulfonic acid 0.288 g (0.003 mol) and dioxane 230 g were added and dissolved. Using a mantle heater as a heat source, the reaction was carried out for 15 hours while maintaining the temperature at 100 ° C. The reaction solution was cooled to 40 ° C. and poured into 2300 g of a 0.05% tetramethylammonium hydroxide aqueous solution to precipitate the resin. The precipitated resin was separated by filtration, washed with ion-exchanged water, and vacuum dried at 130 ° C. and 10 mmHg to obtain 85.6 g of phenol 2C. This compound 1C has a weight average molecular weight (Mw) of 1200, and one having 1 or more structural units represented by the formula (I) is GP.
The C area ratio was 65% (the unreacted spirobiindanediol was 35% in the GPC area ratio).

The resist evaluation methods in the following examples and comparative examples are as follows. All the resist evaluations were performed on a silicon wafer. (1) Sensitivity Exposure time (unit: ms) is defined as the amount of exposure energy at which 1: 1 line & space of 0.50 μm can be formed as designed.
ec). (2) Resolution Indicates the limit resolution (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. The film loss was recognized as "film loss". In addition, the side wall of the pattern having an angle of less than 80 degrees with respect to the substrate was defined as "taper". (5) Exposure margin Line & space with mask dimension 0.40 μm (= 1 /
The resist dimension when the exposure energy of the line pattern of 1) was varied was measured by an electron microscope for length measurement, and the relationship between the exposure energy and the resist dimension was graphed. Resist dimensions of 0.44 μm, 0.40 μm and 0.36
The exposure energy at μm was determined as E1, E2, and E3, respectively, and the value defined by the following equation was calculated as the exposure margin. (Formula) Exposure margin = (E3-E1) x
100 / E2 (6) Focus margin Line & space with mask dimension 0.40 μm (= 1 /
The line pattern of 1) was subjected to dimension measurement and shape observation of the resist pattern when the exposure energy and the focus during stepper exposure were varied. The focus variation range when the resist pattern has a dimension variation within ± 10% of the design dimension and the pattern sidewall (side wall) stands at an angle of 80 ° or more and there is no film loss is expressed as a focus margin.

(Examples 1 and 2, Comparative Example 1) 30 parts by weight of the resin and photosensitizer (photosensitizer synthesized in Reference Example 5) shown in Table 1 were dissolved in ethyl lactate to give a film thickness of 1.17 μm. The solvent content was adjusted so that it could be applied. 0.1% of these solvents
A resist solution was prepared by filtering with a μm Teflon filter (polytetrafluoroethylene filter). However, the other phenol used in Example 2 and Comparative Example 1 is trisphenol PA (manufactured by Honshu Chemical Industry Co., Ltd .; described as TP-PA in the table).

The resist solution was applied onto a silicon wafer by a coater and prebaked at 90 ° C. for 90 seconds to form a resist film having a thickness of 1.07 μm. This wafer was exposed using an i-line stepper NSR1755i7A (manufactured by Nikon Corporation; NA = 0.50) and a test reticle while varying the exposure time, and then the wafer was exposed at 60 ° C. at 110 ° C.
Second exposure bake (Post Exposure Ba
king). Next, it was developed by a paddle method at 23 ° C. for 1 minute with a 2.38% tetramethylammonium hydroxide aqueous solution to form a positive pattern. The wafer was taken out and observed with an electron microscope to observe sensitivity, resolution, remaining film ratio, and pattern shape. The results are shown in Table 1.

[0043]

[Table 1]

(Examples 3 to 4, Comparative Example 2) Positive resist ZIR-9100 (manufactured by Zeon Corporation) was applied to a silicon wafer so that the film thickness after baking under the following conditions would be 0.52 μm. Applied. The baking conditions were 90 ° C. for 90 seconds using a hot plate, and then 300 ° C. for 2 minutes. The refractive index of this film-coated wafer was measured by a spectroscopic ellipsometer, and the reflectance of the i-ray exposure light was measured.
7%. The resist solution shown in Table 2 was applied onto the film-coated wafer (low-reflection substrate) under the condition that the film thickness was 0.95 μm, and then resist evaluation was performed. However, the photosensitizer used in Example 4 and Comparative Example 2 was the photosensitizer synthesized in Reference Example 5, and other phenols were trisphenol PA (manufactured by Honshu Chemical Industry Co., Ltd .; described as TP-PA in the table). Is. The resist coating / evaluation conditions are the same as in Examples 1 and 2.

[0045]

[Table 2]

From these results, it is found that the addition of the phenol (c) improves the sensitivity, the residual film rate, the resolution, the pattern shape, the exposure margin, and the focus margin, and the higher effect can be obtained by using the other phenols together. understood. It was also found that a particularly high exposure margin can be obtained by patterning on a low reflection substrate.

As described above, according to the present invention, it is suitable as a positive working resist of 0.5 μm or less for fine processing, which is excellent in various pattern characteristics.

Claims (2)

[Claims] 1. A positive resist composition containing an alkali-soluble phenol resin, a quinonediazide sulfonate ester-based photosensitizer, and a phenol having a structural unit represented by the following general formula (I). Embedded image (In the formula, R ^{1 and} R ² are each independently a hydrogen atom, a substitutable alkyl group, or a substitutable aryl group.) 2. The positive resist composition according to claim 1, wherein the phenols have a polystyrene reduced weight average molecular weight of 2,000 or less in a GPC pattern using a UV254 nm detector. [0001]