JPH0649136A - Poly@(3754/24)3-hydroxystyrene) partially esterified with tert-butoxycarbonyl group and its production - Google Patents

Abstract

PURPOSE:To obtain a polymer having high developability and high resolution by esterifying part of the hydroxyl groups of a monodisperse poly(3- hydroxystyrene) having a specified molecular weight with tert-butoxycarbonyl groups. CONSTITUTION:Part of the hydroxyl groups of monodisperse poly(3- hydroxystyrene) having a weight-average molecular weight to number-average molecular weight ratio of 1.01-1.5 are esterified with tert-butoxycarbonyl groups to obtain a partially esterified poly(3-hydroxystyrene) comprising repeating units of formulas I and II. The obtained polymer can easily be developed with an alkali and has a narrow molecular distribution and therefore can desirably be used as, e.g. a resist material for LSI. According to this process, the molecular weight can freely and easily be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to monodisperse poly (3-hydroxystyrene) in which a hydroxyl group in a molecule, which is preferably used as a resist material for LSI, is partially esterified with a tert-butoxycarbonyl group and a polydispersible poly (3-hydroxystyrene) thereof. It relates to a manufacturing method.

[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 resist materials used for high-resolution lithography or LSI. In particular, with the recent progress in higher density of LSIs, resist materials are required to have higher resolution and higher developability. As a functional polymer capable of meeting such requirements, novolac resins have hitherto been used. Although it was used in the mainstream, various chemical amplification type resist materials have been studied recently 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 is not only complicated in operation but also has a drawback that it takes time, and it is difficult to sufficiently follow the demanding performance which becomes strict. It could not be a means.

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.
Since the alkali solubility before and after the elimination of the functional group is different, it has high developability and high resolution, and the hydroxyl group in the molecule useful as a resist material or the like is partially esterified with a tert-butoxycarbonyl group. 3-hydroxystyrene) and a method for producing the same.

[0008]

Means and Actions for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has conducted living polymerization of tert-butoxystyrene represented by the following structural formula (3) and Of the monodisperse poly (3-) having a weight average molecular weight ( _Mw ) / number average molecular weight ( _Mn ) of 1.01 to 1.5 by removing the tert-butyl group of
Hydroxystyrene) is obtained, and the hydroxyl group in the polymer is partially tert-butoxycarbonylated to have a repeating unit represented by the following structural formulas (1) and (2), and a molecular weight distribution Is M _w / M _n =
The hydroxyl group in the molecule of 1.01 to 1.5 is partially esterified with a tert-butoxycarbonyl group to form poly (3-
(Hydroxystyrene) is obtained, the molecular weight is easily controlled by this method, and M _w / M _n = 1.01 is ensured.
In addition to giving a monodisperse polymer of ~ 1.5, the monodisperse polymer thus obtained has a tert-butoxycarbonyl group that can be easily eliminated by an acid, It has high developability and high resolution without the troublesome method of separation, which is suitable for use as a base polymer for resist materials as a functional polymer. Therefore, the present invention has been completed and the present invention has been completed.

[0009]

[Chemical 2]

Therefore, the present invention has the repeating units represented by the above structural formulas (1) and (2) and has a molecular weight distribution of weight average molecular weight (M _w ) / number average molecular weight (M _n ) = 1.
A poly (3-hydroxystyrene) in which the hydroxyl group in the molecule is partially esterified with a tert-butoxycarbonyl group, and a weight average molecular weight (M _w ) / number average molecular weight (M Production of the partially esterified poly (3-hydroxystyrene) wherein _n ) is 1.01 to 1.5 and the hydroxyl groups in the monodisperse poly (3-hydroxystyrene) are partially tert-butoxycarbonylated. Provide a way.

The present invention will be described in more detail below. In the poly (3-hydroxystyrene) of the present invention, the hydroxyl group in the molecule having the repeating unit represented by the following structural formulas (1) and (2) has tert-butoxy. It is partially esterified with a carbonyl group.

[0012]

[Chemical 3]

Here, in the poly (3-hydroxystyrene), the ratio of partial esterification of hydroxyl groups in the molecule by t-butoxycarbonyl group is 0.1 to 80% with respect to poly (3-hydroxystyrene). (% By weight, the same applies hereinafter), particularly preferably 5 to 45%.

The poly (3-hydroxystyrene) of the present invention has an M _w / M _n of 1.01 to 1.5, preferably 1.
It is monodisperse and has a molecular weight distribution in the range of 01 to 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 poly (3-hydroxystyrene) is not particularly limited, but when it is used as a resist material, the number average molecular weight is generally in the range of 1,000 to 500,000, particularly 2,000
It is preferably in the range of 300,000. If the number average molecular weight is less than 1,000, the strength as a resist material may not be obtained, and if it exceeds 500,000, there may be a problem in developing characteristics and compatibility, and high resolution and high developing degree may not 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.

The monodisperse partially esterified poly (3-hydroxystyrene) used in the present invention is a monomer (t-butoxystyrene) represented by the following structural formula (3).
Is living-polymerized and then the t-butyl group in the molecule is eliminated.

[0018]

[Chemical 4]

In living polymerization of the above monomers,
It is preferable to use an organometallic compound as the polymerization initiator. Examples of the organic metal compound include organic alkali metals such as n-butyllithium, sec-butyllithium, t-butyllithium, sodium naphthalene, sodium anthracene, sodium α-methylstyrenetetramage, cumylpotassium and cumylcesium. 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.

It is generally desirable to carry out living polymerization 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 monomer in the organic solvent is preferably 1 to 50%, particularly preferably 1 to 30%.

The reaction is preferably carried out under high vacuum or in an atmosphere of an inert gas such as argon or nitrogen with stirring. 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 20 hours.

The reaction is stopped by adding a stopping 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 manner, only the vinyl group in the monomer of the above formula (3) selectively reacts and polymerizes to give a polymer having a repeating unit represented by the following structural formula (4). can get.

[0023]

[Chemical 5]

The copolymer thus obtained is monodisperse and has 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.

Then, the t-butyl group in the polymer represented by the above formula (4) is eliminated to give poly (3-hydroxy) having a phenol residue structural unit represented by the following structural formula (5). Styrene) is obtained.

[0027]

[Chemical 6]

The above t-butyl group elimination reaction can be easily carried out by dropping an acid such as hydrochloric acid or hydrobromic acid in dioxane, acetone, acetonitrile, benzene or the like alone or in a mixed solvent. . In these reactions, the main chain of the polymer is not cleaved and a crosslinking reaction between the molecules does not occur, so that the precursor poly (3
The molecular weight distribution of (tert-butoxystyrene) is maintained as it is, and monodisperse poly (3-hydroxystyrene) having a narrow molecular weight distribution can be obtained.

In this case, the amount of acid added is poly (3-t
ert-butoxystyrene).

Furthermore, the reaction for partially converting the hydroxyl groups in the molecule of the above-mentioned monodisperse poly (3-hydroxystyrene) to t-butoxycarbonylation can be easily carried out in the same manner as the usual t-butoxycarbonylation reaction. be able to.

For example, as a t-butoxycarbonylation reagent, t-butyl chloroformate, di-t-butyl carbonate, t-butoxycarbonylthio- (4,6-dimethylpyridine), t-butylpentachlorophenyl carbonate, 2- (T-butoxycarbonyloxyimino)
Using 2-phenylacetonitrile or the like and pyridine, tetraethylamine or the like as an acid trap solvent, the hydroxyl groups in the monodisperse poly (3-hydroxystyrene) are partially t-butoxycarbonylated. In this case, dimethylamine, 4-N, N-dimethylaminopyridine or the like may be added to the reaction system as a t-butoxycarbonylation catalyst, if necessary. 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.

The mono-dispersed poly (3-hydroxystyrene) can also be prepared by the method of converting poly (3-hydroxystyrene) into a potassium salt using potassium-t-butoxide, and reacting this with potassium di-t-butyldicarbonate. ) Can be partially t-butoxycarbonylated. The t-butoxycarbonylation reaction in the present invention is not limited to the above reaction.

The partially esterified monodisperse poly (3-hydroxystyrene) of the present invention thus obtained has t-
The butoxycarbonylation rate can be easily confirmed by ¹ H-NMR spectrum, and the t-butoxycarbonylation rate is determined from the viewpoint of poly (3 -Hydroxystyrene) 0.1 to 80%, especially 5 to 45%
It is preferably in the range of.

[0034]

The poly (3-hydroxystyrene) partially esterified with the t-butoxycarbonyl group of the present invention
Since it can be acid-developed and has a narrow molecular weight distribution, it is suitable as a photosensitive polymer material such as a high-resolution resist material. Further, according to the production method of the present invention, the monodisperse poly (3-hydroxystyrene) of a partial ester of t-butoxycarbonyl group is produced industrially advantageously by arbitrarily and easily controlling the molecular weight thereof. be able to.

[0035]

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

Example Synthesis of Monodisperse Poly (3-hydroxystyrene) In a 2 liter flask, 1 liter of tetrahydrofuran was used as a solvent, and 1 × sec-butyllithium was used as an initiator.
10 ^-2 mol was charged and mixed. The obtained mixed solution is
After cooling to 78 ° C, 80 g of m-tert-butoxystyrene was added to this solution, and the polymerization temperature was adjusted to 10 at -78 ° C.
When the time-growth reaction was performed, the reaction solution turned red. Then, methanol was added to the obtained reaction solution as a reaction terminator to stop the polymerization reaction, and this solution was poured into methanol to precipitate the obtained polymer, which was separated and dried to give a white 39 g of polymer was obtained.

The measurement results of ¹ H-NMR of the obtained polymer are as follows. 1.4～2.2Ppm :( broad, 3H, -C H ₂ -
C H -) 1.3~1.6ppm :( broad, 9H, -OC (C
H _{3) 3)} 6~7ppm: (broad, 4H, -C ₆ H
_4- )

From the ¹ H-NMR measurement result, it was confirmed that the above copolymer was poly (m-tert-butoxystyrene). The number average molecular weight was measured by the membrane osmometry and found to be 7,000 g / mol. Furthermore, it was confirmed from the results of the GPC elution curve that the monodispersity was extremely high (M _w / M _n = 1.09). The GPC elution curve is as shown in FIG.

Next, 20 g of the above copolymer was added to acetone 3
After adding to 00 ml to dissolve, a small amount of concentrated hydrochloric acid was added at 60 ° C. The obtained solution was stirred for 10 hours, then poured into water, washed and dried to obtain 14 g of a polymer.

The number average molecular weight of this polymer was measured by the membrane osmometry and found to be 5000 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, the polymer was poly (3-hydroxystyrene), and t
It was confirmed to have no ert-butoxy group.

The tert-butoxycarbonyl group is a partial moiety.
Synthesis of stellated poly (3-hydroxystyrene) 50 g of poly (3-hydroxystyrene) obtained by living polymerization (molecular weight 12,000, molecular weight distribution 1.1) was dissolved in 700 ml of pyridine, and at 45 ° C. With stirring, 30 g of di-t-butyl dicarbonate was added. 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.
The reaction solution was added dropwise to 1 liter of water containing 20 g of concentrated hydrochloric acid to obtain a white precipitate. After filtering, the precipitate was dissolved in 300 ml of acetone and added dropwise to 3 liters of water. After filtering the precipitate, it was dried under vacuum at 40 ° C or lower.

The obtained polymer has the repeating units of the above formulas (1) and (2), and the introduction rate of the tert-butoxycarbonyl group was determined using the peak of the OH group at 8 ppm in ¹ H-NMR. As a result, 29.4%
And the molecular weight distribution was 1.15.

[Brief description of drawings]

FIG. 1 is a graph showing a GPC elution curve of poly (m-tert-butoxystyrene) obtained in an example.

FIG. 2 is a graph showing a GPC elution curve of poly (3-hydroxystyrene) obtained in the examples.

Claims (2)

[Claims] 1. A repeating unit represented by the following structural formulas (1) and (2) and having a molecular weight distribution of weight average molecular weight (M _w ) / number average molecular weight (M _n ) = 1.01 to 1. 5. A poly (3-hydroxystyrene) wherein the hydroxyl group in the molecule is 5, which is partially esterified with a tert-butoxycarbonyl group. [Chemical 1] 2. A hydroxyl group in monodisperse poly (3-hydroxystyrene) having a weight average molecular weight (M _w ) / number average molecular weight (M _n ) of 1.01 to 1.5 is partially tert-butoxy. The method for producing poly (3-hydroxystyrene) according to claim 1, wherein carbonylation is performed.