JPH107611A - Pentanuclear novolak compounds and uses thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound useful as a photosensitive agent such as a resist or as a precursor thereof, and to improve resist performance by using the photosensitive agent. SOLUTION: A pentanuclear novolak compound represented by the formula (I) is provided. In the formula, R ^{1 to} R ¹⁰ each independently represent hydrogen, a hydroxyl group or alkyl having 1 to 6 carbon atoms. This compound has 2,
4-bis (2-hydroxy-3-hydroxymethyl-5
-Methylbenzyl) -3,6-dimethylphenol;
It can be produced by reacting an aromatic compound corresponding to a benzene ring at both ends of the formula (I). Further, this can be converted to a quinonediazidesulfonic acid ester to obtain a photosensitive agent. This photosensitive agent is mixed with an alkali-soluble novolak resin to form a resist composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel pentanuclear novolak compound and its application to the field of photosensitizers.

[0002]

2. Description of the Related Art It is generally known that a compound having a phenolic hydroxyl group is converted into a quinonediazide sulfonic acid ester and used as a photosensitive agent in a resist composition for semiconductor fine processing. That is, when a composition containing a compound having a quinonediazide group and a novolak resin is applied to a substrate such as a metal and irradiated with light of 300 to 500 nm, the quinonediazide group is decomposed to generate a carboxyl group, and the alkali-insoluble state is obtained. The composition is used as a positive resist by utilizing the fact that it becomes an alkali-soluble state. Such a positive resist has a feature of being excellent in resolving power, and is therefore used for manufacturing various integrated circuits for semiconductors.

[0003] In recent years, integrated circuits in the semiconductor industry have been steadily miniaturized with high integration, and submicron pattern formation is now required. In order to meet such demands, lithography processes have become an important position in the production of integrated circuits, and even for positive resists, higher resolution (higher γ
Value) is required.

With respect to resist materials containing a quinonediazide compound and a novolak resin, many proposals have been made on combinations of the components. For example, Japanese Patent Application Laid-Open No. 1-189644 (= USP 5,153,096) states that
It discloses that a triphenylmethane-based compound having at least two phenolic hydroxyl groups converted to quinonediazidesulfonic acid is used as a photosensitizer. However, even if such a known photosensitive agent is used,
There is a limit as a resist for fine processing for forming a current ultra-high integrated circuit, that is, for so-called submicron lithography. Therefore, various studies have been made to improve resist performance such as sensitivity, resolution, and heat resistance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive compound which can be used as a sensitizer component of a resist composition, and to produce and provide a novel pentanuclear novolak compound which can be used as a precursor thereof. Is to do.

[0006] Another object of the present invention is to provide a resist composition using the above-mentioned photosensitive compound, which balances various properties such as high sensitivity, high resolution, good profile, good focus tolerance and little development residue. To provide things.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found a pentanuclear novolak compound having a specific structure, and have used a compound obtained by esterifying this compound with quinonediazide sulfonic acid as a photosensitizer. As a result, the above object was achieved, and the present invention was completed.

That is, the present invention provides a pentanuclear novolak compound represented by the following formula (I).

[0009]

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R
⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent hydrogen, a hydroxyl group or alkyl having 1 to 6 carbon atoms.

The pentanuclear novolak compound of the formula (I) is
Starting from 2,4-bis (2-hydroxy-3-hydroxymethyl-5-methylbenzyl) -3,6-dimethylphenol, the aromatic compound necessary for producing the compound of the above formula (I) is added. It can be produced by condensing a compound. Here, the aromatic compounds required to produce the compound of the formula (I) are those represented by the following formulas (II) and (III).

[0012]

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R
⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represent the same meaning as described above.
By using different aromatic compounds of the formulas (II) and (III), compounds having different terminals at the both ends in the formula (I) can be produced, and the compounds of the formula (II) or the formula (III) By using only one compound represented by the formula (I), a compound having the same terminal at both ends in the formula (I) can be produced.

The pentanuclear novolak compound of the formula (I) is reacted with quinonediazidosulfonyl halide to convert at least a part of the hydroxyl groups into quinonediazidesulfonic acid ester to form a photosensitive composition such as a resist composition containing an alkali-soluble novolak resin. Useful as an agent. Accordingly, the present invention also provides a compound in which at least one of the hydroxyl groups of the pentanuclear novolak compound represented by the formula (I) is quinonediazidesulfonic acid esterified, and a photosensitizer containing this ester as an active ingredient. Further, the present invention also provides a resist composition containing such a photosensitive agent together with an alkali-soluble novolak resin.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a pentanuclear novolak compound represented by the formula (I) will be referred to as a "pentanuclear novolak (I)" for simplicity and 2,4-bis (2-hydroxy -3-hydroxymethyl-5-methylbenzyl)-
For the sake of simplicity, 3,6-dimethylphenol is referred to as "trinuclear dimethylol", and a compound in which at least one of the hydroxyl groups in the pentanuclear novolak (I) is quinonediazidesulfonic acid ester is used for simplicity. Ester (I) "
May be called respectively.

The ester (I) is useful as a photosensitive agent that is sensitive to radiation such as near to medium ultraviolet rays and far ultraviolet rays including excimer lasers. In addition, pentanuclear novolak (I) is useful as a precursor of such a photosensitive agent.

In the formula (I), R ¹ , R ² , R ³ , R
⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently hydrogen, a hydroxyl group or an alkyl having 1 to 6 carbons, and examples of the alkyl include methyl, ethyl, Propyl, butyl and the like. In the pentanuclear novolak (I), at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group, and R ⁶ ,
Compounds in which at least one of R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is a hydroxyl group are advantageously prepared.

The pentanuclear novolak (I) can be produced, for example, by reacting the trinuclear dimethylol with the aromatic compounds of the formulas (II) and (III). The trinuclear dimethylol used as a raw material for this reaction is 2,
4-bis (2-hydroxy-5-methylbenzyl)-
3,6-dimethylphenol and formaldehyde,
It can be produced by reacting in the presence of an alkali catalyst. Further, 2,4-bis (2-hydroxy-5-methylbenzyl) -3,6-dimethylphenol is prepared by, for example, reacting 2,5-xylenol with formaldehyde to give 2,4-bis (hydroxymethyl) -3. , 6-dimethylphenol, which can be further condensed with paracresol. 2,4-bis (2-
Up to the production of (hydroxy-5-methylbenzyl) -3,6-dimethylphenol, it can be carried out according to a conventional method. Hereinafter, starting from this compound, the reaction leading to the trinuclear dimethylol, further to the compound (I), and to the ester (I) will be described sequentially.

In the production of trinuclear dimethylol by the reaction of 2,4-bis (2-hydroxy-5-methylbenzyl) -3,6-dimethylphenol with formaldehyde, both reaction raw materials are usually 1: 2 to 10 , Preferably in a molar ratio of 1: 4 to 8. This reaction is carried out in the presence of an alkali catalyst, and the alkali catalyst used here may be any of an inorganic base and an organic base, and particularly, sodium hydroxide, potassium hydroxide, sodium carbonate,
An inorganic base such as potassium carbonate is preferred, and sodium hydroxide is particularly preferred. The alkali catalyst is 2,4-bis (2-hydroxy-5-methylbenzyl) -3,6-
It is used in an amount of usually 0.5 to 8 times, preferably 1 to 5 times the molar amount of dimethylphenol.

This reaction is generally performed in a solvent. As a reaction solvent, tetrahydrofuran, dioxane,
Water, polar solvents such as methanol are preferred, and among them,
A mixed solvent of tetrahydrofuran and water is preferably used. The reaction solvent was 2,4-bis (2-hydroxy-5-
Methylbenzyl) -3,6-dimethylphenol is used preferably in a range of 2 to 30 times by weight. When a mixed solvent of tetrahydrofuran and water is used, the amount of tetrahydrofuran is preferably adjusted to 0.05 to 1 times by weight, more preferably 0.1 to 0.5 times by weight with respect to water.

This reaction is usually carried out at a temperature in the range of about 10 to 60 ° C. In preparing the reactants,
2,4-bis (2-hydroxy-5-methylbenzyl)
A preferred method is to add formaldehyde to a mixture of -3,6-dimethylphenol, an alkali catalyst and a solvent. After completion of the reaction, for example, trinuclear dimethylol is obtained by a method such as neutralization with an acid to precipitate crystals and filtration.

The trinuclear dimethylol has the formula (II) and / or
Or by reacting with an aromatic compound represented by the formula (III),
It is led to a pentanuclear novolak (I). At this time, as described above, by using one or two compounds represented by the formula (II) and / or the formula (III), the compound represented by the formula (I)
The compounds having the same or different terminals at both ends can be produced. When only a compound of the formula (II) is used as an aromatic compound required to produce a pentanuclear novolak (I) by reaction with a trinuclear dimethylol, the following formula (Ia)
A pentanuclear novolak compound represented by the following formula is obtained.

[0023]

Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵
Represents the above-mentioned meaning. In the formula (Ia), R ¹ ,
A compound in which one of R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group and the remaining four are all hydrogen, or one or two of the remaining four are methyl and the remaining two or three are hydrogen , And is advantageously produced from raw material circumstances. In particular, in the formula (Ia), a compound in which R ¹ and R ⁴ are methyl, R ³ is a hydroxyl group, and the remaining R ² and R ⁵ are hydrogen is a compound obtained by subjecting the compound to quinonediazide sulfonic acid esterification. It is preferable because it has excellent performance as an agent.

In the reaction of the trinuclear dimethylol with the aromatic compound of the formula (II) and / or the formula (III), the aromatic compound of the formula (II) and / or the formula (III) It is generally used in a molar ratio of 2 to 50, preferably 4 to 20 with respect to dimethylol. At this time, it is preferable to use an acid catalyst. Acid catalysts include inorganic acids such as hydrochloric acid and sulfuric acid, formic acid, acetic acid, propionic acid,
Any organic acid such as p-toluenesulfonic acid may be used. Among them, mineral acids such as hydrochloric acid and sulfuric acid or p-toluenesulfonic acid are preferable, and p-toluenesulfonic acid is particularly preferably used. The acid catalyst is generally used in an amount of 1 equivalent or less, preferably 0.1 to 0.5, based on the trinuclear dimethylol.
Used in the range of equivalents.

This reaction is preferably carried out in a solvent,
In this case, the reaction solvent can be an alcohol, water, an aromatic solvent, or the like. Examples of the alcohol include lower alcohols such as methanol, ethanol, propanol, and butanol, and among them, methanol is preferably used. Examples of the aromatic solvent include aromatic hydrocarbons such as benzene, toluene, and xylene, and among them, toluene is preferably used. The reaction solvent is used in an amount of generally 0.5 to 5 times by weight, preferably 1 to 3 times by weight, based on the total amount of the aromatic compounds represented by the formulas (II) and (III). Used in. The reaction is usually carried out at a temperature in the range from 10 ° C to the boiling point, preferably in the range from 15 to 60 ° C. This reaction is
Usually proceeds under atmospheric pressure.

The pentanuclear novolak (I) -containing solution obtained by the above-described reaction or by performing appropriate post-treatment if necessary is subjected to any operation such as concentration and crystallization by subjecting the solution to a desired operation. The pentanuclear novolak (I) can be taken out. When the reaction is carried out at around room temperature in an aromatic solvent, as the reaction proceeds, when the reaction is carried out at a higher temperature, it is cooled to around room temperature after completion of the reaction, so that the pentanuclear novolak ( Since the crystal of I) is precipitated, a crude product is obtained by taking out the crystal, and thereafter, any purification means can be applied.
As an extraction or purification means, for example, crystallization from an aromatic solvent can be employed. The crystallization solvent used here can be an aromatic hydrocarbon such as benzene, toluene and xylene, which may be the same or different from those used in the reaction.

The pentanuclear novolak (I) can be used, for example, as an alkali-soluble low molecular weight additive in a resist composition for semiconductor production. For example, quinonediazide sulfonic acid esterification is applied to the resist composition for semiconductor production. It can also be a photosensitive agent. As described above, when pentanuclear novolak (I) is applied to a resist composition for semiconductor production, a crude product after the reaction is dissolved in a solvent having a solubility in water of 9 g / 100 g or less.
It is preferable to reduce the metal content by washing and separating. Here, that the solubility in water is 9 g / 100 g or less means that the maximum amount soluble in 100 g of water at 20 ° C. is 9 g or less. The solvent used here has a solubility of pentanuclear novolak (I) at 20 ° C. of 1 g / 10
It is preferably 0 g or more. Examples of such a solvent include acetates such as ethyl acetate, n-butyl acetate and isoamyl acetate, ketones such as methyl isobutyl ketone and 2-heptanone, and among them, ethyl acetate is preferably used. The solution in which the metal content is reduced in this way can be further crystallized with an aromatic solvent by adding the aromatic solvent. The aromatic solvent used here may be the same as or different from that used in the reaction, but toluene is preferably used.

The pentanuclear novolak (I) thus obtained
When quinonediazide sulfonic acid ester is converted to a photosensitizer, various sulfonic acid derivatives having a 1,2-quinonediazide skeleton, for example, 1,2-quinonediazidosulfonyl halide can be used in the esterification. , 1,2-Naphthoquinonediazide-4- or -5-sulfonyl halide is used. Further, a mixture of 1,2-naphthoquinonediazide-4-sulfonyl halide and 1,2-naphthoquinonediazide-5-sulfonyl halide can also be used. In the esterification reaction, the quinonediazidosulfonyl halide is usually used in a molar ratio of pentanuclear novolak (I) of at least 1.2 to the number of hydroxyl groups in the pentanuclear novolak (I), preferably 1.4 to 1.5. It is used in a molar ratio of 5, more preferably in a molar ratio of 1.4 to 4.

This reaction is usually carried out in the presence of a dehydrohalogenating agent. Examples of the dehydrohalogenating agent include generally basic compounds such as sodium carbonate, inorganic bases such as sodium hydrogencarbonate, ethylamine, ethanolamine, diethylamine, diethanolamine, triethylamine, N, N-dimethylaniline, N, N-dimethylaniline, and the like. Examples include amines such as N-diethylaniline. The dehydrohalogenating agent is generally used in a molar ratio of 1.05 to 1.5, preferably 1.05 to 1.5, based on quinonediazidosulfonyl halide.
It is used in a molar ratio of 1.2, more preferably 1.1 to 1.2.

The esterification reaction is usually performed in a solvent. Examples of the reaction solvent include ethers, lactones, and aliphatic ketones, among which dioxolane,
Preferred are 1,4-dioxane, tetrahydrofuran, γ-butyrolactone, acetone, 2-heptanone and the like.
These can be used alone or in combination of two or more, and 1,4-dioxane is particularly preferable. The reaction solvent is based on the total amount of pentanuclear novolak (I) and quinonediazidosulfonyl halide,
Usually, it is used in the range of 2 to 6 times by weight, preferably in the range of 3 to 5 times by weight. This esterification reaction is carried out under normal pressure,
It proceeds sufficiently at around normal temperature, and generally, a temperature in the range of 20 to 30 ° C. is adopted, and the reaction is performed for about 2 to 10 hours.

After completion of the reaction, the reaction is neutralized with an acid such as acetic acid,
After filtering the solid, the filtrate is mixed with a dilute aqueous acid solution, for example, an aqueous acetic acid solution having a concentration of about 0.1 to 2% by weight.
Ester (I), which is the target substance, precipitates. By filtering, washing and drying this, the ester (I) can be taken out.

The thus esterified compound can be advantageously used as a photosensitive agent which is sensitive to radiation such as near to medium ultraviolet rays and far ultraviolet rays including excimer lasers. This photosensitizer exhibits a high effect when combined with an alkali-soluble novolak resin to form a positive resist composition.

If necessary, 1,2-quinonediazidesulfonic acid ester of another phenolic compound can be used in combination. Specific examples of the quinonediazidesulfonic acid ester used in combination include, for example, JP-A-5-204148.
Compounds described in JP-A-5-323597 (= USP
5,407,778), JP-A-6-167805
(= USP 5,407,779) and the compounds described in JP-A-8-99952 (= EP-A-695,740). In the present invention, when such other quinonediazidesulfonic acid ester is used, the sensitizer including the quinonediazidesulfonic acid ester is used in an amount of 10% based on the total solid content in the resist composition.
It is preferable to contain it in the range of ５０50% by weight.

The alkali-soluble novolak resin constituting the resist composition has at least one phenolic hydroxyl group.
The compound is obtained by condensing a compound having one and an aldehyde in the presence of an acid catalyst, and the type thereof is not particularly limited, and may be various types used in the field of resist. Examples of the phenolic compound as a raw material of the novolak resin include meta-cresol, para-cresol, ortho-cresol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, 2,3,5-trimethylphenol, t-butyl-5-methylphenol, t-butylhydroquinone and the like. Aldehyde, which is another raw material of the novolak resin, includes formaldehyde, acetaldehyde, benzaldehyde, glyoxal, salicylaldehyde and the like. Particularly, formaldehyde is industrially mass-produced as an aqueous solution of about 37% by weight and is preferably used.

A novolak resin is obtained by condensing one or more of such phenolic compounds and one or more of aldehydes in the presence of an acid catalyst. As the catalyst, organic acids, inorganic acids, divalent metal salts and the like are used. Specific examples include oxalic acid, acetic acid,
Examples include p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, phosphoric acid, and zinc acetate. The condensation reaction can be carried out according to a conventional method, for example, at a temperature in the range of 60 to 120 ° C and 2 to 3 times.
It is performed for about 0 hours. Also, even if the reaction is performed in bulk,
It may be performed in a suitable solvent.

The obtained novolak resin is subjected to an operation such as separation for the purpose of reducing the development residue of the resist and the like, and the gel permeation chromatography (GPC)
In a pattern obtained by using a UV254 nm detector, the area ratio of components having a molecular weight of 900 or less in terms of polystyrene is 25% or less, and more preferably 20%, based on the total pattern area excluding the pattern area of the unreacted phenolic compound.
It is preferable to make the following. When performing separation, a novolak resin is converted into a good solvent, for example, alcohols such as methanol or ethanol, acetone, methyl ethyl ketone, ketones such as methyl isobutyl ketone, glycol ethers such as ethyl cellosolve,
A method of dissolving glycol ether esters such as ethyl cellosolve acetate, cyclic ethers such as tetrahydrofuran and the like, and pouring this solution into water to precipitate high molecular weight components, or pentane,
A method of mixing with a poor solvent such as hexane or heptane to carry out liquid separation can be employed.

It is also effective to add an alkali-soluble phenolic compound having a molecular weight of 900 or less to the novolak resin having a high molecular weight component by performing such a separation operation. As the alkali-soluble phenolic compound having a molecular weight of 900 or less, a compound having at least two phenolic hydroxyl groups in the molecular structure is preferable. For example, Japanese Patent Application Laid-Open No. 2-275955 (= EP-A-358,871) and 2-2
No. 560, for example. Molecular weight 90
When using an alkali-soluble phenolic compound of 0 or less, based on the total solid content in the resist composition,
It is preferable to contain it in the range of 3 to 40% by weight.

The resist solution is prepared by mixing and dissolving a photosensitive agent and a novolak resin or, if necessary, an alkali-soluble phenol compound having a molecular weight of 900 or less in a solvent. The solvent used here preferably has an appropriate drying rate and gives a uniform and smooth coating film after the solvent evaporates. Examples of such a solvent include glycol ether esters such as propylene glycol monomethyl ether acetate and ethyl cellosolve acetate, methyl cellosolve acetate, esters such as ethyl pyruvate, n-amyl acetate and ethyl lactate, and 2-heptanone. And ketones such as cyclohexanone; cyclic esters such as γ-butyrolactone; others described in JP-A-2-220056; those described in JP-A-4-362645;
No. 67863, and the like. As the solvent, each compound can be used alone or in combination of two or more.

The resist solution or the resist composition thus obtained may further contain a small amount of an additive such as a resin other than the novolak resin and a dye, if necessary.

[0041]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited by these. In the examples, percentages and parts representing contents or amounts used are by weight unless otherwise specified.

Reference Example 1: 2,4-bis (2-hydroxy-3-hydroxymethyl-5-methylbenzyl)-
Production of 3,6-dimethylphenol

In a four-necked flask, 54.4 parts of 2,4-bis (2-hydroxy-5-methylbenzyl) -3,6-dimethylphenol, 21.6 parts of sodium hydroxide, and 90 parts of water were added.
0 parts and 100 parts of tetrahydrofuran were charged and dissolved, and the temperature was adjusted to 40 ° C. There 37% formalin 73.0
The mixture was added dropwise and stirred at the same temperature for 6 hours. After completion of the reaction, the mixture was neutralized with 36.0 parts of acetic acid and cooled to 25 ° C. The precipitated crystals were filtered and washed with 1000 parts of ion-exchanged water. The obtained filtrate was dried under reduced pressure at 45 ° C. overnight to give 2,4-bis
55.8 parts of (2-hydroxy-3-hydroxymethyl-5-methylbenzyl) -3,6-dimethylphenol were obtained.

Example 1: (1) Production of 2,4-bis [2-hydroxy-3- (4-hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-dimethylphenol

A four-necked flask was charged with 3.8 parts of p-toluenesulfonic acid, 122.2 parts of 2,5-xylenol and 244 parts of toluene, and the temperature was adjusted to 40 ° C. There, 2,4-bis (2-hydroxy-3-hydroxymethyl-5-methylbenzyl) -3, obtained in Reference Example 1,
42.3 parts of 6-dimethylphenol were charged, and the mixture was further stirred at the same temperature for 3 hours. After completion of the reaction, the mixture was cooled to 20 ° C., filtered, and washed with 400 parts of toluene. The obtained filtrate was dissolved in a mixed solution of 400 parts of toluene and 600 parts of ethyl acetate at 60 ° C., and 400 parts of ion-exchanged water was further stirred and separated. Next, washing with 400 parts of ion-exchanged water was performed four times, and then the oil layer was concentrated. 400 parts of toluene was added to the concentrated mass, which was cooled to 20 ° C., filtered, and washed with 200 parts of toluene. The obtained filtrate was dried under reduced pressure at 45 ° C for 24 hours, to give 2,4-bis [2-hydroxy-3- (4-hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-. 22.4 parts of dimethylphenol were obtained.

Mass spectrometry: MS 630 ¹ H-NMR (dimethyl sulfoxide) δ (ppm): 1.8
9 (s, 3H); 1.93 (s, 3H); 1.96 (s, 3H); 1.99 (s, 3
H); 2.01 (s, 3H); 2.05 (s, 3H); 2.06 (s, 3H); 2.15
(s, 3H); 3.73 (s, 4H); 3.78 (s, 2H); 3.94 (s, 2H);
6.21 (s, 1H); 6.27 (s, 1H); 6.30 (s, 1H); 6.33 (s,
1H); 6.57 (s, 2H); 6.69 (s, 1H); 6.71 (s, 1H); 6.72
(s, 1H); 8.10 (s, 1H); 8.11 (s, 1H); 8.26 (s, 1H);
8.88 (s, 2H).

(2) Quinonediazidesulfonic acid esterification

In a four-necked flask, 6.3 of 2,4-bis [2-hydroxy-3- (4-hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-dimethylphenol was added. Part, 1,2-naphthoquinonediazide-
5.4 parts of 5-sulfonyl chloride and 58.5 parts of 1,4-dioxane were charged and the temperature was adjusted to 25 ° C. Thereto, 2.4 parts of triethylamine was added dropwise, followed by a reaction for 3 hours. After completion of the reaction, the mixture was neutralized with 0.6 parts of acetic acid and filtered. The filtrate was mixed with 1000 parts of a 1% aqueous acetic acid solution, stirred for 1 hour, filtered, and washed with ion-exchanged water. The obtained filtrate was dried under reduced pressure at 45 ° C for 24 hours to obtain 10.4 parts of a photosensitizer. This is designated as photosensitive agent a.

Analytical value of main component Mass spectrometry: MS 1094

Example 2: (1) 2,4-bis [2-hydroxy-3- (2-hydroxy-5-methylbenzyl) -5-methylbenzyl]-
Production of 3,6-dimethylphenol

The same operation as in (1) of Example 1 was carried out, except that 108.1 parts of paracresol was used instead of 122.2 parts of 2,5-xylenol, and 2,4-bis [2- Hydroxy-3- (2-hydroxy-5-methylbenzyl)
-5-methylbenzyl] -3,6-dimethylphenol was obtained in an amount of 22.3 parts.

Mass spectrometry: MS 602

(2) Quinonediazidesulfonic acid esterification

2,4-bis [2-hydroxy-3- (4
-Hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-dimethylphenol was replaced by 2,4-bis [2-hydroxy-3- (2-hydroxy-5-methyl). Benzyl) -5-methylbenzyl]-
Using 6.0 parts of 3,6-dimethylphenol,
Except that the amount of dioxane was changed to 57 parts, (2) of Example 1 was used.
By the same operation as described above, 10.3 parts of a photosensitizer was obtained. This is designated as photosensitive agent b.

Analytical value of main component Mass spectrometry: MS 1066

Example 3 (1) Production of 2,4-bis [2-hydroxy-3- (4-hydroxybenzyl) -5-methylbenzyl] -3,6-dimethylphenol

Instead of 122.2 parts of 2,5-xylenol, 94.1 parts of phenol were used and the amount of toluene was 188.
The same operation as in (1) of Example 1 was performed except that
There were obtained 17.3 parts of 2,4-bis [2-hydroxy-3- (4-hydroxybenzyl) -5-methylbenzyl] -3,6-dimethylphenol.

Mass spectrometry: MS 574

(2) Quinonediazidesulfonic acid esterification

2,4-bis [2-hydroxy-3- (4
-Hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-dimethylphenol in place of 6.3 parts, and 2,4-bis [2-hydroxy-3- (4-hydroxybenzyl) -5 -Methylbenzyl] -3,6-dimethylphenol was used, and the same operation as in (2) of Example 1 was carried out except that the amount of 1,4-dioxane was changed to 55.5 parts. 9.9 parts of a photosensitizer were obtained. This is designated as photosensitive agent c.

Analytical value of main component Mass spectrometry: MS 1038

Reference Example 2: Production of novolak resin

In a four-necked flask, meta-cresol 14 was added.
8.5 parts, 121.5 parts of paracresol, 252 parts of methyl isobutyl ketone, 37.0 parts of a 10% oxalic acid aqueous solution and 84.8 parts of a 90% acetic acid aqueous solution were charged, and heated and stirred in a 100 ° C. oil bath. 129.5 parts of 37% formalin 40
The mixture was added dropwise over a period of minutes, and then reacted for another 15 hours. Next, it was washed with water and dehydrated to obtain 466 parts of a methyl isobutyl ketone solution containing 42.3% of a novolak resin. The weight average molecular weight in terms of polystyrene measured by GPC was 4,300.

450 parts of this solution was charged into a separable flask with a bottom, and 909.6 of methyl isobutyl ketone were further added.
And 996.1 parts of n-heptane at 60 ° C.
After stirring for 0 minutes, the mixture was allowed to stand and separated. 380 parts of 2-heptanone was added to the lower layer mass obtained by liquid separation, and methyl isobutyl ketone and n-heptane were removed by an evaporator to obtain a 2-heptanone solution of a novolak resin. The weight average molecular weight in terms of polystyrene by GPC is 9,000, and the molecular weight in terms of polystyrene is 900.
The area ratio in the following range is 14% with respect to the entire pattern area.
Met.

Example of application:

The photosensitive agent shown in Table 1 and the 2-heptanone solution of the novolak resin obtained in Reference Example 2 were converted to a solid content of 15 parts,
1,3-bis [1- (2,4-dihydroxyphenyl) -1-methylethyl] benzene as an additive was added to 3.9.
Parts and 2-heptanone were mixed and dissolved so that the total amount of 2-heptanone was 50 parts. This solution was filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist solution.

On a silicon wafer cleaned by a conventional method,
Using a spin coater, apply the above resist solution so that the film thickness after drying becomes 1.1 μm, and apply 90 μm on a hot plate.
Bake at ℃ for 1 minute. Next, a reduction projection exposure device having an exposure wavelength of 365 nm (i-line) [Nikon Corporation, "N
Using SR 1755I 7A ", NA = 0.5], the exposure amount was changed stepwise. This was developed for 1 minute with a developing solution" SOPD "(manufactured by Sumitomo Chemical Co., Ltd.). Each positive pattern was evaluated as follows, and the results are shown in Table 1.

Effective sensitivity: Display was performed at an exposure amount at which a 0.5 μm line and space pattern became 1: 1.

Resolution: The dimensions of the line-and-space pattern separated at the exposure (effective sensitivity) at which the line-and-space pattern becomes 1: 1 without film loss were measured with a scanning electron microscope.

Γ value: The normalized film thickness (= remaining film thickness / initial film thickness) with respect to the logarithm of the exposure amount is plotted, the slope θ is obtained, and tan θ is defined as the γ value.

Scum: The presence or absence of scum (development residue) was observed with a scanning electron microscope.

When the profile (cross-sectional shape) of the 0.45 μm line-and-space pattern in the effective sensitivity of each positive pattern was observed with a scanning electron microscope, all the patterns were cut vertically.

[0073]

[Table 1]

(Footnote to Table 1) ^* Photosensitive agent x: 1,2,3-trihydroxy-4- (4
-Hydroxy-2,5-dimethylbenzyl) benzene and 1,2-naphthoquinonediazide-5-sulfonyl chloride in a molar ratio of 1: 4

[0075]

The pentanuclear novolak compound represented by the formula (I) according to the present invention is useful as a raw material of a photosensitive agent or an alkali-soluble low molecular weight additive in a resist composition for semiconductor production. In addition, the resist composition containing the quinonediazidosulfonic acid ester of the pentanuclear novolak compound as a photosensitizer has excellent sensitivity and resolution and good balance of various resist properties such as no development residue for semiconductor fine processing. It will be.

Claims (8)

[Claims] (1) Formula (I) (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ ,
R ⁸ , R ⁹ and R ¹⁰ each independently represent hydrogen, a hydroxyl group or an alkyl having 1 to 6 carbon atoms). 2. At least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group, and R ⁶ , R ⁷ , R ⁸ ,
The compound according to claim 1, wherein at least one of R ⁹ and R ¹⁰ is a hydroxyl group. 3. The formula (Ia) Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are
The compound according to claim 1, wherein the compound has the meaning described in (1). 4. ^One of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group and the remaining four are all hydrogen, or one or two of the remaining four are methyl and the remaining two are methyl. Or the compound of claim 3, wherein three are hydrogen. (5) 2,4-bis [2-hydroxy-3- (4
-Hydroxy-2,5-dimethylbenzyl) -5-methylbenzyl] -3,6-dimethylphenol. 6. A compound in which at least one of the hydroxyl groups of the pentanuclear novolak compound according to claim 1 is esterified with quinonediazidesulfonic acid. 7. A photosensitive agent comprising the compound according to claim 6 as an active ingredient. 8. A resist composition comprising an alkali-soluble novolak resin and the photosensitive agent according to claim 7.