JPH0632837A - Poly@(3754/24)m-t-butoxystyrene) and its production - Google Patents

Abstract

PURPOSE:To extremely readily obtain the subject singly dispersible polymer useful as a resist material or photosensitive polymer material having a high resolution degree and a high developing property by anion-polymerizing m- butoxystyrene. CONSTITUTION:m-Butoxystyrene of formula I is anion-polymerized to obtain the objective polymer having repeating units of formula II. Preferably, the living polymerization is performed in the presence of an organic metal compound such as n-butyl lithium as a polymerization initiator in THF in a concentration of 1-40wt.% at -78 to 0 deg.C for 10min to 20hr to produce the objective polymer. For the control of the mol.wt. of the polymer, a polymerization reaction-stopping agent such as methanol is added to the reactional system to stop the reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene derivative and a method for producing the same, and more particularly to a monodisperse poly (m-t-butoxystyrene) useful as a functional polymer and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, functional polymers have been widely used as base polymers for resist materials used for high resolution lithography for LSIs (Large Scale Integrated Circuits). With the progress, functional polymers are required to have higher resolution and higher developability. In order to meet such demand,
Novolak resin is used, but recently,
As an alternative to this, various chemically amplified resist materials have been studied.

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

[0004]

When these polymers are used as a base polymer for a resist material,
The molecular weight and molecular weight distribution have a great influence on the developing characteristics and resolution of the resist material. On the other hand, when the polymer is used as a blending agent, the mechanical properties of the polymer are controlled, or the viscosity of the polymer solution is adjusted, it is desired to control the polymer to have an arbitrary molecular weight.

However, these polymers are polydisperse polymers obtained by a usual radical polymerization method or polycondensation method, and no consideration is given to controlling the molecular weight and the molecular weight distribution from the beginning. Therefore, in order to improve the resolution and developability of the resist, the molecular weight distribution is controlled using a method called fractionation (Japanese Patent Laid-Open No. 62-62-62).
No. 121754), the method of separation is not only an operation that is complicated, but also has a drawback that it takes time, and it is difficult to sufficiently follow the required performance that becomes severe. Therefore, it is an essential means for problem solving. Cannot be

[0006] Therefore, the inventors of the present invention have made extensive studies on polystyrene derivatives, and can easily produce poly (m-t-butoxystyrene) having a narrow molecular weight distribution (referred to as monodispersity), and They have found that they are excellent as polymers for resist materials having high resolution and high degree of development, and have reached the present invention.

Accordingly, a first object of the present invention is to provide a monodisperse poly (m-t-butoxystyrene) suitable for use as a resist material having high resolution and high developability (referred to simply as high resolution). To provide. Second of the present invention
It is an object of the present invention to provide a method for producing monodisperse poly (m-t-butoxystyrene).

[0008]

The above-mentioned objects of the present invention have been achieved by a monodisperse poly (m-t-butoxystyrene) having a repeating unit represented by the following chemical formula 3 and a method for producing the same. .

[Chemical 3]

In the present invention, the monodispersity means that the molecular weight distribution is M _w / M _n = 1.01 to 1.50. Here, M _w is the weight average molecular weight of the polymer, and M _n is the number average molecular weight. In the case of living polymerization, the weight average molecular weight can be easily obtained by calculation from the weight of the monomer and the number of moles of the initiator, or by using a light scattering method. Moreover, the number average molecular weight is easily measured using a membrane osmometer. The molecular weight distribution can be evaluated by gel permeation chromatography (GPC), and the molecular structure is infrared absorption (IR) spectrum or ¹ H.
-Can be easily confirmed by NMR spectrum.

Monodisperse poly (m-t-butoxystyrene) having a repeating unit represented by the above chemical formula 3 of the present invention.
(Hereinafter simply referred to as poly (m-t-butoxystyrene))
Has a molecular weight distribution of 1.01-
It is necessary to be 1.50, but especially 1.03 to
It is preferably 1.30. Molecular weight distribution is 1.50
When it is above, high resolution may be inferior when used as a polymer for resist materials.

The average molecular weight of the poly (m-t-butoxystyrene) of the present invention is not particularly limited, but when it is used as a polymer for a resist material, it is generally in the range of 2,000 to 300,000. Preferably there is. Further, the poly (m-t-butoxystyrene) is
It can be easily produced by anionically polymerizing m-t-butoxystyrene (monomer) represented by the following chemical formula 4, but living polymerization is particularly preferable from the viewpoint of improving the monodispersity of the polymer. It is preferable to manufacture by.

[Chemical 4]

In the above living polymerization, an organometallic compound is used as a polymerization initiator. Examples of the organometallic compound used include n-butyl lithium and se
Organic alkali metal compounds such as c-butyllithium, t-butyllithium, sodium naphthalene, sodium anthracene, potassium naphthalene, sodium α-methylstyrene tetrameride, potassium cumyl, and cumylcesium can be mentioned.

Living polymerization is generally carried out in an organic solvent. The organic solvent used in this case is a solvent such as aromatic hydrocarbon, cyclic ether, and aliphatic hydrocarbon, and specific examples thereof include benzene, toluene, tetrahydrofuran, dioxane, tetrahydropyran, dimethoxyethane, and n-hexane. , Cyclohexane and the like. These organic solvents may be used alone or in combination, but tetrahydrofuran is particularly preferably used.

The concentration of the monomer in the polymerization is appropriately 1 to 40% by weight, and the reaction is carried out under a high vacuum or in an atmosphere of an inert gas such as argon or nitrogen with stirring. The reaction temperature is
It can be arbitrarily selected within a range from −100 ° C. to the boiling temperature of the organic solvent used. In particular, the reaction is preferably carried out at -78 ° C to 0 ° C when a tetrahydrofuran solvent is used, and at room temperature when a benzene solvent is used.

By carrying out the reaction under the conditions as described above for about 10 minutes to 20 hours, only the vinyl group selectively reacts and polymerizes to obtain the polymer represented by the above chemical formula 3.
When the desired degree of polymerization is reached, for example methanol, water,
A living polymer having a desired molecular weight can be obtained by adding a polymerization reaction terminator such as methyl bromide to the reaction system to stop the reaction. Further, the living polymer can be purified and isolated by precipitating the obtained reaction mixture with a suitable solvent such as methanol, washing and drying.

In the living polymerization reaction, 1 monomer is used.
Since the reaction is 00%, the yield of the living polymer produced is about 100%. Therefore, the molecular weight of the living polymer obtained can be appropriately adjusted by adjusting the amount of the monomer used and the number of moles of the reaction initiator. The molecular weight distribution of the living polymer thus obtained is monodisperse ( _Mw / _Mn = 1.01 to 1.50).

[0017]

INDUSTRIAL APPLICABILITY The poly (m-t-butoxystyrene) of the present invention has a narrow molecular weight distribution and can be controlled to an arbitrary molecular weight. Therefore, it is used as a polymer for a high-resolution resist material or a photosensitive polymer material. , A very suitable polymer. Further, according to the production method of the present invention, a monodisperse poly (m-t-butoxystyrene) having a desired molecular weight, which corresponds to the physical properties required depending on the application, can be produced very easily.

[0018]

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

Example 1. In the examples, poly (m-t-
For the synthesis of (butoxystyrene), a monomer of m-t-butoxystyrene was distilled in the presence of CaH ₂ and then purified using sodium benzophenone to remove impurities such as water before use.

In a 1 liter flask, 800 ml of tetrahydrofuran as a solvent and n as a polymerization initiator
After charging 2 × 10 ⁻³ mol of butyllithium and cooling to −20 ° C., the mt-butoxystyrene monomer 3 was added.
0 g (dissolved in 50 ml of tetrahydrofuran-78
(Cooled to 0 ° C) was added and the living polymerization initiation reaction was carried out at -20 ° C for 1 hour. When the growth reaction was further performed at -78 ° C for 6 hours, the solution turned red.

After confirming that the desired degree of polymerization has been reached,
Methanol was added to the reaction solution to terminate the living polymerization reaction. Next, the obtained reaction mixture was poured into methanol to precipitate the polymer, which was separated and dried to obtain 30 g of a white polymer. When the ¹ H-NMR spectrum and IR spectrum of the obtained polymer were measured, the polymer was
It is poly (m-t-butoxystyrene) in which the active end remains unreacted with the t-butoxy group, and the result of GPC elution curve (FIG. 1) shows that it is monodisperse (M _w / M _n = 1). .0
It was confirmed to be 1 to 1.50).

The results of the above ¹ H-NMR 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)} 6.0~7.0ppm :( broad, 4H, C ₆ H ₄₎ The number-average molecular weight measured by membrane osmometry was 1.3 × 10 ⁴ g / mol.

Example 2 A 2.2-liter flask was charged with 1,300 ml of tetrahydrofuran as a solvent and 1 × 10 ^-3 mol of cumylcesium as a polymerization initiator,
After cooling to -78 ° C, 50 g of mt-butoxystyrene monomer purified in the same manner as in Example 1 (100 ml).
50 g of a white polymer was obtained in exactly the same manner as in Example 1 except that the solution was dissolved in tetrahydrofuran and cooled to −78 ° C.) and the living polymerization reaction was carried out for 30 minutes.

The ¹ H-NMR spectrum of the obtained polymer was measured and found to have the same characteristic absorption as that of the polymer obtained in Example 1. Therefore, the obtained polymer had a t-butoxy group. The active end remains unreacted, poly (m-
It was confirmed to be monodisperse (M _w / M _n = 1.10) from the result of GPC elution curve (FIG. 3). The number average molecular weight measured by the membrane osmometry was 55,000 g / mol.

[Brief description of drawings]

1] GP of poly (m-t-butoxystyrene) synthesized in Example 1 (number average molecular weight 13,000 g / mol)
It is a C elution curve.

2 is a GP of poly (m-t-butoxystyrene) synthesized in Example 2 (number average molecular weight: 55,000 g / mol).
It is a C elution curve.

Claims (2)

[Claims] 1. A monodisperse poly (m-t-butoxystyrene) having a repeating unit represented by the following chemical formula 1. [Chemical 1] 2. The method for producing poly (m-t-butoxystyrene) according to claim 1, wherein m-butoxystyrene represented by the following chemical formula 2 is anionically polymerized. [Chemical 2]