JPH02173114A - Production of novolak resin - Google Patents

Abstract

PURPOSE:To obtain the subject resin having excellent dry etching resistance, heat resistance, etc., and useful as a raw material for positive type photoresists by polycondensing a phenolic compound having sulfonic acid (salt) group and phenolic compound without the above-mentioned group with a carbonyl compound. CONSTITUTION:(A) A phenolic compound having sulfonic acid and/or sulfonate group (e.g. o-phenolsulfonic acid or 1-naphthol-2-sulfonic acid) and a phenolic compound (e.g. alpha-naphthol or o-cresol) without the sulfonic acid (salt) group are polycondensed with (B) a carbonyl compound (e.g. formaldehyde or acrolein), preferably at 1:(0.7-1.5) molar ratio of the components (A) to (B) to afford the objective resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a novolak resin, and particularly to a method for producing a novolak resin containing a sulfonic acid and/or a sulfonate.

[Conventional technology]

The alkali-soluble novolac resin is useful as a raw material for producing a positive resist by blending with a 1,2-quinonediazide compound. The above-mentioned positive resist is used when manufacturing integrated circuits, but in recent years, as there has been a demand for improved integration of integrated circuits, it has become important to ensure that the resulting resist pattern is faithful to the mask pattern and achieves high resolution. It is widely used because it can. On the other hand, in order to increase the degree of integration of integrated circuits, the etching method has been changed from the conventionally mainstream wet etching method to the dry etching method, but in the dry etching method, the temperature of the substrate increases, The resist pattern may undergo thermal deformation, reducing dimensional accuracy, or may be damaged by highly reactive fluorine ions, chlorine ions, etc. Therefore, positive resists are required to have extremely high heat resistance and dry etching resistance.

The present inventors attempted to improve the heat resistance and dry etching resistance of a positive resist by sulfonating an alkali-soluble novolak resin as a raw material.

[Problem to be solved by the invention]

However, when novolac resin is sulfonated after synthesis, the novolac resin often turns into a gel.
There is a problem in that it is difficult to use as a raw material for positive resists.

[Means to solve the problem]

Therefore, an object of the present invention is to provide a method for producing a novolank resin containing sulfonic acid and/or sulfonate without causing gelation.

That is, the present invention solves the above problems, and provides (A) a phenol compound having a sulfonic acid and/or a sulfonate salt (hereinafter referred to as a "sulfonated phenol compound") and a phenol compound having no sulfonic acid and a sulfonate salt. The present invention provides a method for producing Tuvolac resin, which includes a step of polycondensing a phenol compound (hereinafter simply referred to as "phenol compound") with (B) a carbonyl compound.

Examples of the sulfonated phenol compound include compounds represented by the following format (1) or format (II).

General formula (I): H [Here, R' is a hydrogen atom, a halogen atom, a hydroxyl group,
Hydrocarbon group, alkoxy group, alkoxycarbonyl group,
Arylcarbonyl group, alkyloxy group, arylcarbonyl group, alkyloxy group, arylcarbonyl group, alkyloxy group,
means a loyloxy group, an acyl group, a cyan group or a nitro group, and X means a hydrogen atom or an ammonium ion] - Format (■): H [Here, R' and X are as described above, and the above phenol As a compound, for example, the following format (In)
or a compound represented by the form (TV).

General formula (■): [Here, the plurality of R1s may be the same or different, as described above] General formula (■): H [Here, the plurality of R1s may be the same or different, and the same as described above] Specific examples of R'' in general formulas (I) to (IV) include hydrogen atom, hydroxyl group, cyano group, nitro group, halogen atom such as chlorine atom, fluorine atom, and bromine atom; methyl group,
Alkyl groups such as ethyl, propyl and butyl groups; aryl groups such as phenyl, tolyl and cumyl; alkenyl groups such as vinyl, propenyl, allyl and butenyl; aralkyl such as benzyl and phenethyl groups. Examples include hydrocarbon groups represented by the following groups; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; acyl groups such as acetyl, propionyl, butyryl, and valeryl;

Among the compounds represented by the formula (1) or (II) used as one of the components (A) in the method of the present invention, preferred are those in which the total number is a hydrogen atom, an alkyl group, or an alkoxy group. be.

Specific examples of the compound represented by general formula (1) include 0-
Phenolsulfonic acid, m-phenolsulfonic acid, p
-phenolsulfonic acid, 4-sulfonic acid-2-methylphenol, 4-sulfonic acid-3-methylphenol,
4-sulfonic acid-2-ethylphenol, 4-sulfonic acid-3-ethylphenol, 4-sulfonic acid-2-butylphenol, 4-sulfonic acid-2-butylphenol,
Examples include ammonium 0-phenolsulfonate, ammonium m-phenolsulfonate, ammonium P-phenolsulfonate, and the like. Specific examples of the sulfonated phenol represented by the -format (n) include 2-sulfonic acid-1-naphthol, 3-sulfonic acid-1-naphthol, 4-sulfonic acid-1-naphthol, and 5-sulfonic acid-1-naphthol. M-1-naphthol, 2-methyl-5-sulfonic acid-
1 naphthol, 2-methyl-4-sulfonic acid-1-naphthol, 2-ethyl-4-sulfonic acid-1 naphthol,
2-Butyl-4-sulfonic acid-1-naphthol, 2-acetoxy-4-sulfonic acid-1-naphthol, 1-acetoxy-4-sulfonic acid-1-naphthol, 2-methoxy-
4-sulfonic acid-1-naphthol, 1-methoxy-4-
2-naphthol sulfonic acid, 2-methoxycarbonyl-4-sulfonic acid to 1-naphthol, 2-acetyl-4
-Sulfonic acid-1-naphthol, 2-ammonium sulfonate-1-naphthol, 3-ammonium sulfonate-1-naphthol, 4-ammonium sulfonate-1-
Naphthol, ammonium 5-sulfonate-1-naphthol, ammonium-1-2-methyl-5-sulfonate
Naphthol, ammonium-1-naphthol 2-methyl-4-sulfonate, ammonium-1-naphthol 2-ethyl-4-sulfonate, and the like.

Among these, preferred are p-phenolsulfonic acid, m-phenolsulfonic acid, ammonium phenolsulfonate, ammonium m-phenolsulfonate, ammonium p-phenolsulfonate,
-Methyl-4-sulfonic acid-1-naphthol, 2-methyl-5-sulfonic acid-1-naphthol, 2-methoxy-
4-sulfonic acid-1-naphthol, 2-ammonium sulfonate-1-naphthol, 3-ammonium sulfonate-1-naphthol, 4-ammonium 1-sulfonate
-naphthol, ammonium 5-sulfonate-1-naphthol, and the like.

These sulfonated phenol compounds can be used alone or in combination of two or more.

Note that the sulfonated phenol compound is preferably used in the form of a sulfonate in order to improve the polymerization conversion rate.

Among the compounds represented by -form (I[I) or (IV) used as another constituent compound of component (A) in the method of the present invention, preferred are compounds in which R1 is a hydrogen atom, a hydroxyl group, or an alkyl group. or an aryl group.

Specific examples of compounds represented by general formulas (1) and (IV) include α-naphthol, β-naphtholphenol, 0-cresol, m-cresol, p-cresol,
0-ethylphenol, m-ethylphenol, P-ethylphenol, 0-butylphenol, m-butylphenol, P-butylphenol, 3,5-xylenol, 2.4-xylenol, 2,5-xylenol, 3
．． 4-xylenol, 2,3.5-1-limethylphenol, 0-phenylphenol, p-phenylphenol, isopropenylphenol, 0-tolylphenol, p-)ruylphenol, 0-styrylphenol, p-styrylphenol , 0-cinnamylphenol, p-cinnamylphenol, 0-acetoxyphenol, m-acetoxyphenol, P-acetoxyphenol, 0-benzoyloxyphenol, m-benzoyloxyphenol, P-benzoyloxyphenol, 0- Methoxyphenol, m-methoxyphenol, p-methoxyphenol, 0-methoxycarbonylphenol,
Examples include m-methoxycarbonylphenol, p-methoxycarbonylphenol, 0-acetylphenol, m-acetylphenol, p-acetylphenol, p-hydroxydiphenyl, and the like. Among these, preferred are phenol, 0-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,
4-xylenol, 3.5-xylenol, 2,3.5
- Trimethylphenol, o-(-7'delphenol, mt-styrylphenol, pt-butylphenol, p-hydroxydiphenyl, etc.).

These phenol compounds can also be used singly or in combination of two or more.

The amount of the phenol compound used is usually a molar ratio of sulfonated phenol compound/phenol compound of 1/99 to 5.
0150, preferably 1/99 to 40/60. If the amount of the phenolic compound used is small, the novolac resin that is produced is likely to gel, and if the amount of the phenol compound used is too large, the dry etching resistance of the positive resist prepared using the resulting novolac resin will be affected. and the improvement in heat resistance becomes insufficient.

Examples of the carbonyl compound used as component (B) in the method of the present invention include compounds represented by the following formula (V).

(V) Z [Here, the plurality of R2s may be the same or different, and mean a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, or an aralkyl group, and may have a substituent. ] Specific examples of the alkyl group, aryl group, alkenyl group and aralkyl group represented by R2 in the -format (V) include those exemplified for R1 in the -format (1).

- Examples of the carbonyl compound represented by the formula (V) include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde,
Phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, tolylhenzaldehyde, mesitylbenzaldehyde, phenethylbenzaldehyde, 0-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, O-chlorobenzaldehyde, m-chlorobenzaldehyde , p-chlorobenzaldehyde,
0-Nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, 0-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, P-ethylhenzaldehyde, p-n
-Aldehydes such as butylhenzaldehyde, acrolein, crotonaldehyde, and cinnamaldehyde; and ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl phenyl ketone, and methyl benzyl ketone. Among these,
Formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, acrolein,
Acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl phenyl ketone, methyl benzyl ketone and the like are preferred.

These carbonyl compounds can be used singly or in combination of two or more.

The carbonyl compound as component (B) is preferably 0.7 to 2 mol, particularly preferably 0.7 to 2 mol, particularly preferably 0.7 to 2 mol, per mol of the sulfonated phenol compound and phenol compound as component (A).
It is used in a proportion of 7 to 1.5 moles. This ratio is 0.7
If it is less than 2 moles, there will be a large amount of unreacted substances remaining, resulting in a low softening point of the obtained novolak resin, and if it exceeds 2 moles, the novolac resin will easily gel.

The polycondensation of the sulfonated phenol compound and phenol compound as component (A) and the carbonyl compound as component (B) is usually carried out using an acid catalyst. Examples of the acid catalyst include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, or formic acid;
Examples include organic acids such as oxalic acid and acetic acid. The amount of this acid catalyst to be used is usually 1X10-' to 5
IQ-1 mol, preferably IX10-' to 5X10
−'Mole.

In polycondensation, no reaction medium may be used (but
For example, water, hydrophilic solvents, etc. can also be used as reaction medium. Examples of hydrophilic solvents used in this case include alcohols such as methanol, ethanol, propatool, and butanol, ethers such as tetrahydrofuran, dioxane, and diglyme, esters such as ethyl acetate, propyl acetate, and butyl acetate, or acetonitrile.
Nitriles such as propionitrile and butyronitrile are mentioned. The amount of these reaction media used is usually (A)
The amount is not more than 5000 parts by weight, preferably 10 to 1000 parts by weight, per 100 parts by weight of the sulfonated phenol compound and phenolic compound as components. If it exceeds 5,000 parts by weight, polycondensation will slow down.

The reaction temperature in polycondensation is appropriately selected depending on the reaction raw materials, but is usually 10 to 200" C1, preferably 60 to 1
It is 60°C. If the reaction temperature is less than 10"C, the polycondensation is slow, and if the reaction temperature exceeds 200"C, the resulting novolak resin is likely to gel.

Further, the polycondensation is preferably carried out under pressure in a closed system filled with an inert gas, such as nitrogen gas, helium gas, argon gas, etc. Usually, the difference between the internal pressure and the external pressure is 1 to 5.
0 kg/cffl, preferably 3 to 25 kg/c
ffl. After the completion of polycondensation, in order to remove the unreacted raw materials, acid catalyst, and reaction medium present in the system, the internal temperature is raised to 130 to 230 °C for boat fishing, and volatile components are distilled off under reduced pressure. , recover the novolak resin.

Furthermore, after the completion of polycondensation, the reaction product can be precipitated by dissolving the reaction system in the hydrophilic solvent and adding it to a large amount of a precipitant such as water, n-hexane, petroleum ether, or n-hebutane. , novolak resin can also be recovered.

In addition, the sulfonic acid and/or
Or the content of sulfonate is preferably 1 to 20
% by weight, particularly preferably from 1 to 15% by weight.

〔Example〕

Example 1 In a flask, 127 g of phenol, 54 g of p-t-butylphenol, 17 g of ammonium p-phenolsulfonate, [phenol/p-t-butylphenol/
Ammonium p-phenolsulfonate = 75/201
5 (molar ratio)), 131 g of a 37% by weight aqueous formaldehyde solution, and 0.08 g of oxalic acid, and while stirring, the flask was placed in an oil bath and reacted for 4 hours while maintaining the internal temperature at 100°C.

Thereafter, the oil bath temperature was raised to 150°C, and at the same time the pressure inside the flask was reduced to remove unreacted phenol, p-1-butylphenol, ammonium p-phenolsulfonate, formaldehyde, water, and oxalic acid.

Then, the molten novolazo resin was returned to room temperature and collected. The recovered novolac resin did not contain gel.

The yield of novolak resin was 202 g, and the polycondensation content of ammonium p-phenolsulfonate was 8.6% by weight.

Examples 2 to 11 Novolac resins were synthesized and recovered in the same manner as in Example 1, except that the compounds shown in Table 1 were used in the amounts shown as the phenol compound and the sulfonated phenol compound, respectively. None of the recovered novolak resins contained gel. The yield and the polycondensation content of ammonium P-phenolsulfonate or ammonium 4-sulfonate-1 naphthol are shown in Table 1.

Comparative Example 1 164 g of novolak resin was synthesized in the same manner as in Example 1, except that no sulfonated phenol compound was used at all, and 135 g of phenol and 54 g of pL-butylphenol were used as the phenol compounds.

50 g of the obtained novolac resin was mixed with 25% by weight of oleum and heated at 50° C. for 8 hours to sulfonate, and the novolak resin was gelled.

Test Examples 1 to 11 10 g of novolac resin obtained in Examples 1 to 11 and (2
,4-dihydroxyphenyl)methane-1゜2-naphthoquinonediazide-5-sulfonic acid tetraester 2.5
g was dissolved in 37.5 g of propylene glycol monoethyl ether acetate and filtered through a filter with a pore size of 0.2 μm to prepare a solution.

The resulting solution was spin-coated onto a silicon wafer having a silicon oxide film using a spinner, and then pre-haked at 90°C for 2 minutes to form a 1.0 μm thick resist film.

Next, wavelength 43 is transmitted through a pattern mask for resolution testing.
After irradiating with ultraviolet light having a wavelength of around 6 nm, it was developed with a 2.3% by weight tetramethylammonium hydroxide aqueous solution and rinsed with water to form a resist pattern.

The silicon wafer having this resist pattern was placed on a hot plate for 5 minutes, and the temperature of the hot plate and plate and the state of thermal deformation of the resist pattern were observed. The maximum temperature at which the resist pattern did not deform was defined as the heat resistance temperature.

Furthermore, the silicon wafer with a resist pattern was attached to a parallel plate type plasma etching apparatus (electrode spacing 40 mm), and the output was 100 W, tetrafluoromethane/oxygen (
9515 (capacity ratio)] and a gas pressure of 15 pa, the dry etching resistance of the resist pattern is determined by the selectivity of the resist pattern (ratio of the rate at which the silicon oxide film is etched to the rate at which the resist pattern is etched).
Investigated by.

These results are shown in Table 2.

According to the production method of the present invention, a novolak resin in which the phenol moiety is sulfonated can be easily produced without causing gelation, which occurs when the novolac resin is sulfonated after synthesis.

The novolak resin obtained by this method is useful as an alkali-soluble novolak resin as a raw material for positive resist having excellent dry etching resistance, heat resistance, etc.

Claims (1)

[Scope of Claims] A novolac resin comprising the step of polycondensing (A) a phenol compound having a sulfonic acid and/or a sulfonic acid salt and a phenol compound having no sulfonic acid and a sulfonic acid salt, with (B) a carbonyl compound. Production method