JPH0632850A - P-hydroxystyrene-hydroxy-alpha=methylstyrene block copolymer partially esterified with t-butocarboxyl group and its production - Google Patents

Abstract

PURPOSE:To obtain the subject copolymer having a narrow mol.wt. distribution, capable of being developed with an alkali, having a high developing property and a high resolving property, and useful for resist materials, etc., by t- butoxycarbonylating the hydroxyl groups of the polyhydroxystyrene parts, etc., in a specific copolymer. CONSTITUTION:The hydroxyl groups of the poly p-hydroxystyrene parts and the poly p-hydroxy-alpha-methylstyrene parts in a singly dispersible p- hydroxystyrene-p-hydroxy-alpha-methylstyrene block copolymer having a weight- average mol.wt. (Mw)/number-average mol.wt. (Mn) of 1.01-1.5 are partially t-butoxycarbonylated to provide the objective copolymer having repeating units of formulas I, II, III and IV.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention uses the tert-butoxycarbonyl group to partially esterify the hydroxyl groups of the poly-p-hydroxystyrene portion and poly-p-hydroxy α-methylstyrene portion, which are preferably used as resist materials for LSI. The present invention also relates to a monodisperse p-hydroxystyrene-p-hydroxy α-methylstyrene block copolymer and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Functional polymers are often used as base polymers for high-resolution lithography or resist materials used for LSI. In particular, with the recent progress in higher density of LSIs, resist materials are required to have higher resolution and higher developability. Conventionally, novolak resins have been the mainstream as a functional polymer capable of meeting such demands. However, in recent years, various chemically amplified resist materials have been studied as alternatives.

Of the above-mentioned chemically amplified resist materials, those having a functional group which is easily eliminated by an acid and having different solubilities before and after elimination of the functional group are particularly preferred from the viewpoint of workability. ing. As such a resist material, a polystyrene derivative having excellent plasma resistance is known to be particularly suitable.

When these polymers are used as a base polymer for resist, their molecular weight and molecular weight distribution have a great influence on the developing characteristics and resolution of the resist, but these polymers are usually subjected to a radical polymerization method or a condensation polymerization method. Since it is a polydisperse polymer obtained by, it is not considered from the beginning to control the molecular weight and the molecular weight distribution.Therefore, in order to improve the developability and resolution of the resist, the molecular weight is controlled using a method called fractionation. There is.

However, the method of separation has the drawback that not only the operation is complicated but also it takes time.
Since it is difficult to adequately follow the demanding performance that becomes strict, it could not be an essential means for solving the problem.

Therefore, it has been desired to develop a high quality polymer suitable as a base polymer for a resist material.

The present invention has been made in order to meet the above-mentioned demand, and has a functional group that is easily eliminated by an acid.
Polyp-, which is useful as a resist material and the like, can be easily developed with an alkali because of its different solubility before and after elimination of the functional group, and has high developability and high resolution.
To provide a p-hydroxystyrene-p-hydroxy alpha methyl styrene block copolymer in which hydroxyl groups of a hydroxy styrene moiety and a poly p-hydroxy alpha methyl styrene moiety are partially esterified with a tert-butoxycarbonyl group, and a method for producing the same. With the goal.

[0008]

MEANS TO SOLVE THE PROBLEMS As a result of intensive studies to achieve the above object, the present inventor has found that p-tert-butoxy α-methylstyrene represented by the following structural formula (5) and the following structural formula ( After performing living polymerization with p-tert-butoxystyrene represented by 6), te in the molecule
After removing the rt-butyl group or performing living polymerization of p-methoxymethoxy α-methylstyrene represented by the following structural formula (7) and p-methoxymethoxystyrene represented by the following structural formula (8), By removing the methoxymethyl group in the molecule, the weight average molecular weight (M
_w ) / number average molecular weight (M _n ) of 1.01 to 1.5, a monodisperse block copolymer of p-hydroxystyrene and p-hydroxy α-methylstyrene is obtained, and the block copolymer By partially tert-butoxycarbonylating the hydroxyl groups of the poly p-hydroxystyrene portion and the poly p-hydroxy α-methylstyrene portion in the united product, the following structural formulas (1), (2), (3) and ( 4) having a repeating unit represented by 4) and having a molecular weight distribution of M _w / M _n = 1.01 to 1.5, the hydroxyl groups of the poly p-hydroxystyrene portion and the poly p-hydroxy α-methylstyrene portion are tert. -P-hydroxystyrene partially esterified with butoxycarbonyl group and p-
A block copolymer with hydroxy α-methylstyrene can be obtained. This method makes it easy to control the molecular weight and ensures that the monodisperse block copolymer having M _w / M _n = 1.01 to 1.5 is obtained. The monodisperse block copolymer thus obtained has a tert-butoxycarbonyl group which can be easily eliminated by an acid,
It can be easily developed with alkali and has high developability and high resolution without the troublesome method of separation due to monodispersity. Therefore, it can be used as a functional polymer such as a base polymer for resist materials. The present invention has been completed by finding that it can be suitably used for applications.

[0009]

[Chemical 2]

Therefore, the present invention provides the above structural formula (1),
Poly having the repeating units represented by (2), (3) and (4) and having a molecular weight distribution of weight average molecular weight (M _w ) / number average molecular weight (M _n ) = 1.01 to 1.5 Hydroxyl groups of p-hydroxystyrene and poly-p-hydroxy α-methylstyrene are partially esterified with tert-butoxycarbonyl group to form p-hydroxystyrene-
p-hydroxy α-methylstyrene block copolymer, and weight average molecular weight (M _w ) / number average molecular weight (M _n ) of 1.
01-1.5 monodisperse p-hydroxystyrene and p
The hydroxyl groups of the poly-p-hydroxystyrene part and the poly-p-hydroxy-α-methylstyrene part in the block copolymer with -hydroxy-α-methylstyrene are partially te.
Provided is a method for producing a block copolymer of rt-butoxycarbonylated p-hydroxystyrene and p-hydroxy α-methylstyrene.

The present invention will be described in more detail below. The block copolymer of the present invention has the following structural formulas (1), (2),
It has the repeating units represented by (3) and (4), and the hydroxyl groups of the poly-p-hydroxystyrene portion and the poly-p-hydroxy α-methylstyrene portion are respectively tert-.
It is partially esterified with a butoxycarbonyl group.

[0012]

[Chemical 3]

Here, the repeating units of the above formulas (1), (2), (3) and (4) may be contained in any proportion, but usually the weight fraction is 0.01 ≦ (1). ≤99.97,
0.01 ≦ (2) ≦ 99.97, 0.01 ≦ (3) ≦ 9
9.7, 0.01 ≦ (4) ≦ 99.7, (1) + (2)
+ (3) + (4) = 1 is preferable, and when the block copolymer of the present invention is used as a resist material, the difference in solubility during development of the resist and the crosslinking are preferable. 20 ≦ (1) ≦ 9 from the viewpoint of reaction control
9.97, 20 ≦ (2) ≦ 99.97, 0.01 ≦
(3) ≤ 50, 0.01 ≤ (4) ≤ 50, more preferably 50 ≤ (1) ≤ 99.97, 50 ≤ (2) ≤ 99.9.
7, 0.01 ≦ (3) ≦ 45, 0.01 ≦ (4) ≦ 45
Is preferred.

Furthermore, in the above block copolymer, the ratio of partial esterification of hydroxyl groups in the molecule by t-butoxycarbonyl groups is relative to the hydroxyl groups of poly-p-hydroxystyrene and poly-p-hydroxy α-methylstyrene. 0.1 to 80% (wt%, the same applies below), especially 5 to 45%
Is preferred.

The above-mentioned p-hydroxystyrene and p of the present invention
The block copolymer with -hydroxy α-methylstyrene has an M _w / M _n of 1.01 to 1.5, preferably 1.01.
It is a monodisperse polymer having a molecular weight distribution in the range of 1.3. Those having M _w / M _n less than 1.01 are technically difficult to synthesize, and if it exceeds 1.5, it is impossible to obtain a high resolution and a high degree of development that can be used as a resist material. The weight average molecular weight (M _w ) can be measured by a light scattering method, and the number average molecular weight (M _n ) can be measured by a membrane osmometer.

Further, the average molecular weight of the above block copolymer is not particularly limited, but when it is used as a resist material, the number average molecular weight is generally 500 to 50.
It is preferably in the range of 30,000, particularly preferably in the range of 3,000 to 300,000. If the number average molecular weight is less than 500, the resist material may not have film strength.
If it exceeds 50,000, there is a problem in developing characteristics and compatibility,
In some cases, high resolution and high development degree cannot be obtained.

The molecular weight distribution can be evaluated by gel permeation chromatography (GPC), and the molecular structure can be easily confirmed by ¹ H-NMR spectrum.

In the present invention, the monodisperse partially esterified p-hydroxystyrene-p-hydroxy α-methylstyrene block copolymer mentioned above is a monodisperse p-hydroxystyrene-p-hydroxy α-methylstyrene as shown below. It can be easily obtained by partially esterifying the hydroxyl group of the block copolymer with a t-butoxycarbonyl group.

First, a monodisperse block copolymer of p-hydroxystyrene and p-hydroxy α-methylstyrene is subjected to living polymerization of two kinds of monomers represented by the following structural formulas (5) and (6). Then, it can be obtained by removing the t-butyl group in the molecule.

[0020]

[Chemical 4]

Further, the monodisperse block copolymer of p-hydroxystyrene and p-hydroxy α-methylstyrene is obtained by subjecting two kinds of monomers represented by the following structural formulas (7) and (8) to living polymerization. It can also be obtained by eliminating the methoxymethyl group in the molecule.

[0022]

[Chemical 5]

In living polymerization of the above-mentioned monomer, it is preferable to use an organometallic compound as a polymerization initiator. Examples of the organometallic compound include n-butyllithium, sec-butyllithium, t-butyllithium, sodium naphthalene, sodium anthracene,
Examples thereof include organic alkali metals such as α-methylstyrene tetramargin sodium, cumyl potassium, and cumyl cesium. The amount of the polymerization initiator added depends on the molecular weight of the produced polymer and is calculated from the molecular weight and the weight of the monomer (molecular weight = weight of the monomer / mol number of the initiator).

Living polymerization is generally desirably carried out in an organic solvent. Examples of the organic solvent include aromatic hydrocarbons, cyclic ethers, aliphatic hydrocarbon solvents and the like, and specific examples thereof include benzene, toluene, tetrahydrofuran, dioxane, tetrahydropyran, dimethoxyethane, n-hexane and cyclohexane. These organic solvents may be used alone or in combination of two or more. The concentration of the above-mentioned both monomers (formula (5) and formula (6) or formula (7) and formula (8)) in the organic solvent is preferably 1 to 50%, particularly preferably 1 to 30%.

The reaction is preferably carried out under high vacuum or under stirring in an inert gas atmosphere such as argon or nitrogen. The reaction temperature can be freely selected from −100 ° C. to the boiling point temperature of the organic solvent used, but it is particularly preferable to carry out the reaction at −78 ° C. to 0 ° C. with a tetrahydrofuran solvent and at room temperature with a benzene solvent. Also, the reaction is usually about 1
It is suitable to carry out for 0 minutes to 30 hours.

The reaction is stopped by adding a terminating agent such as methanol, water or methyl bromide to the reaction system. Then, the obtained reaction mixture solution is precipitated in a suitable solvent, for example, methanol, washed and dried to purify and isolate the polymer produced by the polymerization reaction. When the living polymerization reaction is carried out in this way, in the reaction of the monomers of the above formulas (5) and (6), only the vinyl group in both monomers selectively reacts and polymerizes, and the following structural formula (9) And the block copolymer having the repeating units represented by (10) is obtained.

[0027]

[Chemical 6]

Further, also in the reaction of the monomers of the above formulas (7) and (8), only vinyl groups in both monomers selectively react and polymerize, and are represented by the following structural formulas (11) and (12). A block copolymer having repeating units is obtained.

[0029]

[Chemical 7]

The copolymer thus obtained is a monodisperse polymer having a molecular weight distribution M _w / M _n of 1.01 to 1.5.

Since the yield of the polymer in the above reaction is almost 100%, the molecular weight of the obtained polymer can be easily calculated from the weight of the monomer used and the number of moles (number of molecules) of the polymerization initiator.

Next, a t-butyl group in the copolymer having the repeating units represented by the above formulas (9) and (10) or a copolymer having the repeating units represented by the above formulas (11) and (12). When the methoxymethyl group in the polymer is eliminated, a block copolymer of p-hydroxystyrene having a phenol residue structural unit represented by the following structural formulas (13) and (14) and p-hydroxy α-methylstyrene Is obtained.

[0033]

[Chemical 8]

The elimination reaction of the above t-butyl group and methoxymethyl group is carried out by dioxane, acetone, acetonitrile,
This can be easily carried out by dropping an acid such as hydrochloric acid or hydrobromic acid in benzene or the like alone or in a mixed solvent.
In these reactions, the main chain of the polymer is not cleaved and the crosslinking reaction between molecules does not occur,
The molecular weight distribution of the copolymer of p-t-butoxystyrene or p-methoxymethoxystyrene and p-t-butoxy α-methylstyrene or p-methoxymethoxy α-methylstyrene, which is a precursor, is maintained as it is, A narrow monodisperse copolymer of hydroxystyrene and styrene and hydroxy α-methylstyrene can be obtained.

In this case, the amount of the acid added is pt-butoxystyrene or p-methoxymethoxystyrene and p-.
It may be added in an equimolar amount or more with t-butoxy α-methylstyrene or p-methoxymethoxy α-methylstyrene.

Further, the hydroxyl groups of the poly-p-hydroxystyrene part and the poly-p-hydroxy-α-methylstyrene part of the block copolymer of the above-mentioned monodisperse p-hydroxystyrene and p-hydroxy α-methylstyrene are each partially The reaction for t-butoxycarbonylation can be easily carried out in the same manner as the usual t-butoxycarbonylation reaction.

For example, as a t-butoxycarbonylation reagent, t-butyl chloroformate, di-t-butyl carbonate, t-butoxycarbonylthio- (4,6-dimethylpyrazine), t-butylpentachlorophenyl carbonate, Using 2- (t-butoxycarbonyloxyimino) -2-phenylacetonitrile and the like and using pyridine, tetraethylamine and the like as an acid trap solvent, monodisperse poly-p-hydroxystyrene portion and poly-p-hydroxy α-methyl are used. The hydroxyl groups in the styrene portion are partially t-butoxycarbonylated. in this case,
If necessary, dimethylamine, 4-N, N-dimethylaminopyridine or the like may be added to the reaction system as a t-butoxycarbonylation catalyst. The amount of t-butoxycarbonylation reagent used is proportional to the t-butoxycarbonylation rate, and the amount of t-butoxycarbonylation catalyst added can be a catalytic amount. Further, the amount of the acid trap solvent used is preferably equimolar to the t-butoxycarbonylation reagent.

Also, using potassium-t-butoxide, p-hydroxystyrene, styrene and hydroxy α
The block copolymer with methylstyrene is made into a potassium salt, and this is reacted with di-t-butyl dicarbonate to obtain monodispersed p-hydroxystyrene and p-hydroxystyrene.
The copolymer with hydroxy α-methylstyrene is partially
-Can be butoxycarbonylated. The t-butoxycarbonylation reaction in the present invention is not limited to the above reaction.

The t-butoxycarbonylation rate of the partially esterified monodisperse p-hydroxystyrene-p-hydroxy α-methylstyrene copolymer of the present invention thus obtained is easily confirmed by ¹ H-NMR spectrum. As described above, the t-butoxycarbonylation rate is higher than that of p-hydroxystyrene and p-hydroxyα-methylstyrene from the viewpoint of the difference in solubility during resist development and the control of the crosslinking reaction. It is preferably in the range of 0.1 to 80%, particularly 5 to 45%.

[0040]

INDUSTRIAL APPLICABILITY The p-hydroxystyrene-p-hydroxy α-methylstyrene block copolymer partially esterified with a t-butoxycarbonyl group of the present invention can be alkali-developed and has a narrow molecular weight distribution. It is suitable as a photosensitive polymer material such as a resist material. Further, according to the production method of the present invention, the molecular weight of the p-hydroxystyrene-p-hydroxy α-methylstyrene block copolymer of the monodisperse t-butoxycarbonyl group partial ester can be arbitrarily and easily controlled. Can be manufactured industrially advantageously.

[0041]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[Example] Monodispersed p-hydroxystyrene and p-hydroxy α-meth
Synthesis of block copolymer with tylstyrene In a 3 liter flask, 2500 ml of tetrahydrofuran as a solvent and 1 × 1 of n-butyllithium as an initiator.
0 ^-2 mol was charged and mixed. The obtained mixed solution is -7
After cooling to 8 ° C., 50 g of p-tert-butoxystyrene was added to this solution, the polymerization reaction was carried out while stirring for 2 hours, then 50 g of p-tert-butoxy α-methylstyrene was added, and the mixture was stirred for 10 hours. While carrying out the polymerization reaction, the reaction solution turned red. Then, methanol was added as a reaction terminator to the obtained reaction solution,
After stopping the polymerization reaction, this solution was poured into methanol to precipitate the obtained polymer, which was separated and dried to obtain 100 g of a white polymer.

The ¹ H-NMR measurement results of the obtained polymer are as follows.

[0044]

[Chemical 9]

From the results of ¹ H-NMR measurement, the above copolymer was found to contain 50% p-tert-butoxy α-methylstyrene.
And p-tert-butoxystyrene 50% was confirmed to be a copolymer. Moreover, when the number average molecular weight was measured by a membrane osmometry, it was found to be 9000 g /
It was a mole. Furthermore, it was confirmed from the results of the GPC elution curve that the monodispersity was extremely high ( _Mw / _Mn = 1.11). The GPC elution curve is as shown in FIG.

Next, 100 g of the obtained copolymer was added to 1 liter of acetone to dissolve it, and a small amount of concentrated hydrochloric acid was added at 60 ° C. After stirring the resulting solution for 8 hours,
When this solution was poured into water, washed and dried, 72 g of a polymer was obtained.

The number average molecular weight of this polymer was measured by the membrane osmometry and found to be 6500 g / mol.
Moreover, the result of having evaluated the molecular weight distribution of this polymer by GPC is as shown in FIG. 2, and it was confirmed that it was a copolymer having extremely high monodispersity. Furthermore, from the ¹ H-NMR measurement results of the polymer obtained here, tert-
Since a peak derived from a butyl group was not observed, it was confirmed that the polymer was a copolymer of p-hydroxystyrene and p-hydroxy α-methylstyrene and had no tert-butyl group. .

A partial tert-butoxycarbonyl group
Stellized p-hydroxystyrene and p-hydroxy
Synthesis of Block Copolymer with Si-α-methylstyrene 50 g of a copolymer of p-hydroxystyrene and p-hydroxyα-methylstyrene (molecular weight 6500, molecular weight distribution 1.11) obtained by the above-mentioned living polymerization was added to pyridine 70
Dissolve in 0 ml and stir at 45 ° C. with dicarbonate di-t.
-Add 16 g of butyl. A gas was generated at the same time as the addition, but the reaction was further continued for 1 hour in a N ₂ stream. Concentrated hydrochloric acid 20
The reaction solution was added dropwise to 1 liter of water containing g to obtain a white precipitate. After filtration, precipitate and dissolve in 50 ml of acetone,
It was added dropwise to 1 liter of water. After filtering the precipitate, it was dried under vacuum at 40 ° C or lower.

The obtained polymer has the above formula (1),
It has a repeating unit of (2), (3) and (4), and the introduction rate of the tert-butoxycarbonyl group was determined by using the peak of the OH group at 8 ppm in ¹ H-NMR. The result was 15%. The molecular weight distribution was 1.10.

[Brief description of drawings]

FIG. 1 is a graph showing a GPC elution curve of a block copolymer of p-tert-butoxystyrene and p-hydroxyαmethylstyrene obtained in an example.

FIG. 2 shows p-hydroxystyrene and p obtained in Examples.
FIG. 7 is a graph showing a GPC elution curve of a block copolymer with -hydroxy α-methylstyrene.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Fujio Yagihashi 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Shin-Etsu Chemical Co., Ltd. Corporate Research Center

Claims (2)

[Claims] 1. A repeating unit represented by the following structural formulas (1), (2), (3) and (4), and having a molecular weight distribution of weight average molecular weight (M _w ) / number average molecular weight (M _n). ) = 1.
P-hydroxystyrene-p- in which the hydroxyl groups of the poly-p-hydroxystyrene portion and the poly-p-hydroxy α-methylstyrene portion are partially esterified with tert-butoxycarbonyl groups, respectively.
Hydroxy α-methyl styrene block copolymer. [Chemical 1] 2. A block copolymer of monodisperse p-hydroxystyrene and p-hydroxy α-methylstyrene having a weight average molecular weight (M _w ) / number average molecular weight (M _n ) of 1.01 to 1.5. The p-hydroxystyrene-p-hydroxy alpha methyl styrene block copolymer according to claim 1, wherein the hydroxyl groups of the poly p-hydroxy styrene moiety and poly p-hydroxy alpha methyl styrene moiety are partially tert-butoxycarbonylated. Manufacturing method.