JPH05112606A - Method for synthesizing acid-degradable polymer compound - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as resists for producing semiconductor elements for forming micro-patterns of high accuracy in high purity by reacting an alkali-soluble polymer with a reagent capable of providing acid-degradable groups in the presence of a specific catalyst. CONSTITUTION:The objective compound is obtained by reacting (A) an alkali- soluble polymer compound (preferably a phenolic novolak resin, etc.) with (B) a reactional reagent (preferably a dialkyl carbonate compound such as di-t-butyl dicarbonate) for providing protecting groups degradable with acids in the presence of (C) a catalyst composed of a pyridine compound (e.g. 2- aminopyridine) in an amount of 0.05-10mol% based on the component (B). In the compound, 5-50% functional groups capable of providing the alkali solubility are protected with the acid-degradable protecting groups. Furthermore, the reaction is preferably carried out in an inert gas atmosphere such as argon at 0-100 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing an acid-decomposable polymer compound used as a resist for manufacturing a semiconductor device used for forming a highly precise fine pattern.

[0002]

2. Description of the Related Art Patterning for fine processing of semiconductor elements and the like is widely performed by photolithography. At this time, a resist that is sensitive to actinic rays such as radiation is used, and conventionally, as such a material, a material that decomposes upon irradiation with radiation or a compound that cures upon irradiation with radiation has been used as a resist. However, since these compounds only undergo a sequential reaction and react with irradiation energy, their efficiency is extremely low,
As a result, the reality is that significant improvement in sensitivity cannot be expected.

In recent years, in order to solve such problems, a resist based on the idea of a chemical amplification mechanism has been studied.
This is a method of thermally accelerating a reaction other than light by using an acid generated upon irradiation of light as a catalyst. In this method, the irradiation amount of light only needs to generate a catalytic amount of acid, and extremely high sensitivity can be achieved.

In these methods, a compound having a functional group which is easily decomposed by an acid is used. For example, in Japanese Patent Publication No. 27660/1990, poly (P-butoxycarbonyloxystyrene) is a short wavelength photoresist material. (Takumi Ueno et al., Organic Electronics Materials Study Group, Bunshin Publishing, 1988, P. 66-68), butoxycarbonylphenol compounds are examined as useful compounds.

[0005]

However, since these compounds are easily decomposed by an acid, they are synthesized under the condition that a basic compound containing an alkali metal is used. There is a drawback that the ionic impurities of remain. When these metals are present in the resist, there are problems such as impairing the characteristics of the semiconductor element, and on the other hand, in order to remove them, a complicated process is required, resulting in a significant cost increase. Was unavoidable. The present invention is to provide a synthetic method that solves the above problems by introducing a synthetic method utilizing a catalytic reaction.

[0006]

The present invention provides an alkali-soluble polymer compound in which 5 to 50% of the functional group that imparts alkali-solubility is protected by a protecting group that is decomposed by an acid. And a reaction reagent which gives a protecting group which is decomposed by an acid, in the synthesis by a reaction with a reaction reagent which gives a protecting group which is decomposed by an acid.
The reaction is carried out under the condition in which 05 to 10 mol% of the pyridine compound is present.

As the catalyst used in the present invention, any compound can be used without any exception as long as it is a pyridine compound, but a compound having a substituent that activates the nitrogen atom of the pyridine ring is used as a particularly useful catalyst. can do.

Specific examples of such a compound include:
For example, 2-aminopyridine, 4-aminopyridine,
2,4-diaminopyridine, 2- (N, N-dimethylamino) pyridine, 4- (N, N-dimethylamino) pyridine, 2,4-di (N, N-dimethylamino) pyridine, 2- (N , N-diethylamino) pyridine, 4-
(N, N-diethylamino) pyridine, 2,4-di (N, N-diethylamino) pyridine, 2,4,6-tri (N, N-dimethylamino) pyridine, 2,4,6-
Examples thereof include tri (N, N-diethylamino) pyridine, 2-methoxypyridine, 4-methoxypyridine, 2,4-dimethoxypyridine, and 2,4,6-trimethoxypyridine. In addition, pyridine and alkyl group substitution Pyridine, phenyl group-substituted pyridine and the like can also be used.

The alkali-soluble polymer compound to be reacted in the present invention preferably has a structure excellent in dry etching resistance, and examples of materials which meet this purpose include phenol novolac resin, cresol novolac resin and naphthol novolac resin. Examples thereof include a phenol / formaldehyde resin, a polyvinylphenol resin, or a copolymer of vinylphenol and an acrylic or styrene monomer.

In these polymer compounds, the functional group which gives alkali solubility of the alkali-soluble polymer compound is protected by an acid-decomposable protective group in an amount of 5 to 50%, and the average molecular weight thereof is further reduced. From a practical point of view, it is desirable that the number is about 2,000 to 50,000.

A dialkyldicarbonate compound is preferable as a reaction reagent for providing a protective group which is decomposed by an acid, and examples thereof include di-t-butyl dicarbonate, di-t-amyl dicarbonate and di (1,1,1 ( Examples thereof include triethyl) methyl) dicarbonate.

In the present invention, the pyridine compound is added in an amount of 0.05 to 10 mol% with respect to the reaction reagent which gives a protective group which is decomposed by an acid, under an inert gas stream under conditions of 0 to 10 mol%. The reaction can be performed at a temperature of -100 ° C. If it is less than 0.05 mol%, the effect of the catalyst does not appear. If it is more than 10 mol%, the reactivity is excellent, but the ratio of the catalyst remaining in the final product is large, and when it is used as a resist, There is a risk of impairing the characteristics. Further, when the reaction temperature is 0 ° C or lower, the reaction rate is low and the time required for the reaction is long, while when it is 100 ° C or higher,
The reaction product is decomposed at the same time as the reaction and the production yield is reduced. Further, in order to suppress the by-products of the reaction, it is preferable to carry out the reaction in an atmosphere of an inert gas such as argon or nitrogen.

The practice of this invention is typically carried out using a reaction solvent. Any solvent can be used without any exception as long as it does not interfere with the reaction of the above components. For example, specifically, benzene, toluene, xylene, diethyl ether, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cellosolve acetate, dimethyl glyme,
Dimethyl diglyme, isoamyl acetate, etc. can be used. The polymer compound synthesized by the method of the present invention can be used as a useful material for a resist for microfabrication, which requires fine patterning such as a semiconductor device and a printed wiring board.

[0014]

In the present invention, a pyridine compound is used as a reaction catalyst instead of a conventionally used basic compound containing an alkali metal, and a reaction that gives an alkali-soluble polymer and a protecting group that is decomposed by an acid The reaction with the reagent proceeds rapidly. Moreover, the above pyridine compound is an organic compound, and if it is highly purified by a commonly known purification method such as distillation, recrystallization, sublimation or the like before it is used as a catalyst, the reaction system is free from alkali metal and the like. The desired high molecular compound can be synthesized with high purity without mixing ionic impurities. Further, since it is used as a reaction catalyst, a complicated reaction process is not required, and the target compound can be synthesized at low cost.

[0015]

EXAMPLES The present invention will be described below with reference to specific examples. However, it can be applied to the reaction of not only polymer compounds but also relatively low molecular weight compounds such as bisphenol A, bisphenol F, and trisphenol compounds. Needless to say, the present invention is not limited to these examples.

Example 1 24 g (0.2 mol) of poly-p-vinylphenol (Mw = 8000, contents of Na and K were 2.0 ppm and 0.3 ppm, respectively) was dissolved in 300 mL of tetrahydrofuran, and the solution was placed under a nitrogen stream. The mixture was stirred uniformly at 30 ° C. Then 0.244 g (0.
(002 mol) of 4- (N, N-dimethylamino) pyridine was added, and 13.0 g (0.06 mol) of di-t-butyl dicarbonate was added dropwise at such a rate that the temperature did not rise.
After further stirring at 30 ° C. for 4 hours, the reaction product was added to distilled water to reprecipitate the polymer, and the obtained polymer was thoroughly washed with water and dried at room temperature and reduced pressure for 20 hours.

As a result of measuring the infrared absorption spectrum of the obtained polymer, an absorption based on a butoxycarbonyl group was recognized at 1760 cm ^-1 , and the reaction proceeded almost quantitatively from the measurement by a nuclear magnetic resonance apparatus. It was confirmed. The amount of metallic impurities was measured by atomic absorption spectroscopy, and Na
Of 0.7 ppm and K of 0.1 ppm were obtained. This value was sufficiently good for use as a material for a semiconductor resist.

Comparative Example 1 24 g (0.2 mol) of poly-p-vinylphenol (Mw = 8000, Na and K contents were 2.0 ppm and 0.3 ppm, respectively) was dissolved in 300 mL of tetrahydrofuran and stirred under a nitrogen stream. did. Then, 7.8 g (0.06 mol) of potassium t-butoxide was added, and 10 minutes later, 13.08 g (0.0
(6 mol) di-t-butyl dicarbonate was added dropwise. Four
After stirring at room temperature for a period of time, the reaction product was poured into distilled water and then thoroughly washed with water to recover the reaction product. The obtained polymer was thoroughly washed with water and dried at room temperature under reduced pressure for 20 hours.

As a result of measuring the infrared absorption spectrum of the obtained polymer, an absorption based on a butoxycarbonyl group was recognized at 1760 cm ⁻¹ , and the measurement by a nuclear magnetic resonance apparatus showed almost quantitative analysis as in Example 1. It was confirmed that the reaction was proceeding. However, when the amount of metallic impurities was measured by the atomic absorption spectrometry, it was found to be 7 pp as Na.
The m and K values were 100 ppm, which were too high for use as a material for a resist for semiconductors, and this synthesis method was unsuitable as a resist material synthesis method.

Examples 2 to 11 Depending on the pyridine compound shown in Table 1, the reaction solvent and the reaction conditions, and from the reaction reagents shown in Table 1 and polyvinylphenol (the molecular weight and the metal content are the same as those in Example 1), various types of compounds were obtained. A molecular compound was synthesized. The reaction of the obtained polymer compound was confirmed by the same operation as in Example 1, and the purity was measured by the same method as in Example 1. As a result, the concentration of metal impurities was almost the same level as in Example 1. I confirmed that (N
a as 0.3 to 0.8 ppm and K as 0.05 to 0.2 ppm
).

[0021]

[Table 1]

Examples 12 to 15 Depending on the pyridine compound shown in Table 2, the reaction solvent, and the reaction conditions, and from the reaction reagents shown in Table 2 and the novolac resin (the molecular weight and the metal content are the same as those in Example 1), various polymers were prepared. The compound was synthesized. The reaction of the obtained polymer compound was confirmed by the same operation as in Example 1, and the purity was measured by the same method as in Example 1. As a result, the metal impurity concentration was found to be in Example 1.
It was confirmed that the level was almost the same as (0 for Na.
5 to 0.9 ppm, and K as 0.1 to 0.3 ppm).

[0023]

[Table 2]

[0024]

According to the method for synthesizing an acid-decomposable polymer compound of the present invention, since an organic compound containing virtually no alkali metal or containing an alkali metal in an extremely low content is used as a reaction catalyst, The above-described acid-decomposable polymer compound having high purity can be synthesized. Therefore, the use of such an acid-decomposable polymer compound makes it possible to synthesize a pattern forming material that solves the above problems, which is extremely useful.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoko Tanaka 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Sanryu Electric Co., Ltd. Material and Device Research Laboratory (72) Hideo Horibe 8 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Materials 1-1, Sanryo Electric Co., Ltd. (72) Inventor Hiroshi Kozuka 8-1-1 1-1 Tsukaguchihonmachi, Amagasaki-shi, Hyogo Sanryo Electric Co., Ltd.

Claims (1)

[Claims] 1. An alkali-soluble polymer compound in which 5 to 50% of an alkali-soluble functional group used for a resist for manufacturing a semiconductor device is protected by a protecting group which is decomposed by an acid is referred to as an alkali-soluble polymer. In the case of synthesizing by reaction with a reaction reagent that gives a protecting group that is decomposed by an acid, 0.05 to 10 mol% of a pyridine compound is present relative to the reaction reagent that gives a protecting group that is decomposed by an acid. A method for synthesizing an acid-decomposable polymer compound, which comprises reacting under the conditions of: