JPH0641244A - Monodisperse copolymer and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a monodisperse copolymer satisfactory in the performance required of a polymer for use in a resist material by the anionic polymn. of two kinds of specific styrene deriv. monomer. CONSTITUTION:A monomer of formula I is copolymerized with a monomer of formula II by anionic polymn. to obtain a monodisperse copolymer having units of formula III and units of formula IV. The anionic polymn. may be conducted in a solvent-free system, but is pref. conducted in an org. solvent from the viewpoint of easy control of the reaction rate, etc. The use of tetrahydrofuran in particular as the org. solvent is preferable. The copolymer has a narrow as the org. solvent is preferable. The copolymer has a narrow mol.wt. distribution and is monodisperse, and hence, is satisfactory in the performance required of a polymer for use in a resist material with a high resolution.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel copolymer and a method for producing the same, and more particularly to a monodisperse copolymer excellent as a functional polymer and a method for producing the same.

[0002]

2. Description of the Related Art Functional polymers are widely used as polymers for resist materials used in high resolution lithography when manufacturing LSIs (Large Scale Integrated Circuits) used in computers and the like. In recent years, with the development of LSI manufacturing technology, the degree of integration of LSI has become higher and higher, and a resist material having a high resolution and a high developability capable of coping with the higher density has been demanded.

To increase the resolution of the resist material,
It is theoretically known that it is effective to narrow the molecular weight distribution of the polymer used (monodispersity).
Controlling the polymer to an arbitrary molecular weight is also effective when compatibilizing the polymer as a blending agent, controlling the mechanical properties of the polymer, or adjusting the viscosity of the polymer solution. It is a means.

Conventionally, novolac resins have been used as such polymers for resist materials. In this case,
A method called fractionation has been used to control the molecular weight distribution (for example, Japanese Patent Laid-Open No. 62-121754). However, such a method of classification has the drawback that not only the operation is complicated but also that it takes time, and it is difficult to adequately follow the demanding performance that becomes strict, so that an essential problem solving is not possible. Is desired.

On the other hand, a chemically amplified resist material having a functional group which is easily eliminated by an acid and having different solubilities before and after the elimination of the functional group is excellent in workability, and therefore the manufacturing efficiency of LSI or the like is improved. Various studies have been conducted to improve the quality. As such a chemically amplified polymer for a resist material, a styrene derivative polymer having excellent plasma resistance is known.

[0006]

However, since the polymer of the styrene derivative used as the polymer for the resist material is conventionally produced by the radical polymerization method or the condensation polymerization method, it is difficult to control the molecular weight and the molecular weight distribution. Therefore, it is difficult to produce a polymer of a monodisperse styrene derivative that sufficiently satisfies the required performance as a polymer for a resist material. Therefore, the inventors of the present invention have made earnest studies on polymers of styrene derivatives, and have found a novel monodisperse copolymer satisfying the required performance as a polymer for resist materials and a method for producing the same, and arrived at the present invention.

Therefore, a first object of the present invention is to provide a novel monodisperse copolymer satisfying the required performance as a polymer for a resist material. A second object of the present invention is to provide a novel method for producing a monodisperse copolymer which satisfies the required performance as a polymer for a resist material and can be controlled to have an arbitrary molecular weight.

[0008]

The above-mentioned various objects of the present invention are achieved by a monodisperse copolymer comprising a unit represented by the following chemical formula 5 and a unit represented by the following chemical formula 6, and a method for producing the same. Was done.

[Chemical 5]

[Chemical 6]

In the present invention, the monodispersity means the ratio M _W / M of the weight average molecular weight M _W and the number average molecular weight M _n of the copolymer.
It means that _n is 1.01 to 1.50. In the case of living polymerization, the weight average molecular weight can be easily calculated by calculating from the weight of the monomer and the number of moles of the initiator, or by using the light scattering method. Further, the number average molecular weight is easily measured using a membrane osmometer.

The molecular weight distribution can be evaluated by gel permeation chromatography (GPC), the molecular structure of which is infrared absorption (IR) spectrum or ¹ H.
-It can be easily confirmed by the NMR spectrum. Further, the randomness of the copolymer can be easily confirmed by the value of Tg (glass transition point) measured using DSC.

The monodisperse copolymer composed of the units represented by the chemical formulas 5 and 6 of the present invention is obtained by anionic polymerization of the monomer represented by the following chemical formula 7 and the monomer represented by the following chemical formula 8. It can be easily manufactured.

[Chemical 7]

[Chemical 8]

In the present invention, a living anionic polymerization initiator is used in the anionic polymerization of the monomer represented by Chemical Formula 7 and the monomer represented by Chemical Formula 8 from the viewpoint of improving monodispersibility. It is preferable to use an organometallic compound. Preferred organometallic compounds include, for example, n-butyllithium and sec
Examples include organic alkali metal compounds such as butyl lithium, tert butyl lithium, sodium naphthalene, potassium naphthalene, sodium anthracene, sodium α-methylstyrene tetrameride, potassium cumyl, and cumylcesium.

In the present invention, the anionic polymerization can be carried out in a non-solvent system, but it is preferably carried out in an organic solvent from the viewpoint of easy adjustment of the reaction rate. Preferred organic solvents include aromatic hydrocarbon solvents such as benzene and toluene, cyclic ether solvents such as tetrahydrofuran, dioxane and tetrahydropyran, and aliphatic hydrocarbon solvents such as dimethoxyethane, n-hexane and cyclohexane. These organic solvents may be used alone or in combination, but tetrahydrofuran is particularly preferably used.

The concentration of all the monomers (the monomer represented by Chemical formula 7 and the monomer represented by Chemical formula 8) in the organic solvent in the polymerization reaction is preferably 1 to 40% by weight. The polymerization reaction is preferably carried out under high vacuum or in the presence of an inert gas such as nitrogen from the viewpoint of preventing reaction with oxygen and the like. The reaction temperature can be appropriately selected within a range from -100 ° C to the boiling point of the reaction solution. When using a tetrahydrofuran solvent, the range of -78 ° C to 0 ° C is preferable, and when using a benzene solvent, room temperature is preferable.

By carrying out the polymerization reaction for about 10 minutes to 30 hours, the monodisperse copolymer having the units of the above chemical formulas 5 and 6 can be obtained. To stop the polymerization reaction,
For example, it can be carried out by adding a terminating agent such as methanol, water, methyl bromide, etc., whereby a copolymer having a desired molecular weight can be easily obtained. In this case, since the active end during the polymerization reaction has a color peculiar to the anion, the termination of the polymerization reaction can be easily confirmed by the presence or absence of this color.

When a block polymer is obtained as a copolymer, one monomer is polymerized, the other monomer is added, and the polymerization reaction is performed again. A random copolymer is used as the copolymer. When it is obtained, the monomer represented by Chemical formula 7 and the monomer represented by Chemical formula 8 may be mixed in advance, and the obtained mixture may be polymerized. When living anionic polymerization is carried out, the monomer reacts 100%, so the molecular weight of the polymer obtained by adjusting the amount of the monomer used and the number of moles (number of molecules) of the living anion initiator added. Can be controlled appropriately.

The molecular weight distribution of the copolymer thus obtained is monodisperse (M _w / M _n = 1.01 to 1.5).
0). In the present invention, the number average molecular weight of the copolymer is 5
It may be in the range of 00 to 500,000, but is particularly preferably in the range of 3,000 to 300,000. Further, a copolymer containing the repeating unit represented by the above Chemical formula 5 or 6 in an arbitrary ratio can be produced, but usually, (the repeating unit represented by the Chemical formula 5) / ( The molar ratio of the repeating units represented is (0.01-9)
The range is 9.99) / (99.99 to 0.01).

[0018]

Since the novel copolymer of the present invention has a narrow molecular weight distribution and is monodisperse, it satisfies the required performance as a polymer for a resist material having high resolution. Particularly, the block copolymer of the polymer represented by Chemical formula 5 and the polymer represented by Chemical formula 6 is suitable as a polymer for a resist material. Further, according to the production method of the present invention, the molecular weight can be controlled as desired, so that a monodisperse copolymer having physical properties suitable for the intended use can be easily produced.

[0019]

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

EXAMPLE 1 Into a 1-liter flask were charged 1200 ml of tetrahydrofuran as a solvent and 2 × 10 ^-3 mol of n-butyllithium as an initiator, mixed and cooled to -78 ° C., and then pt-butoxystyrene. 45
g was added and a polymerization reaction was carried out for 1 hour. Next, 5 g of m-t-butoxystyrene was added, and the polymerization reaction was carried out while stirring for 20 hours. The reaction solution turned red.

Next, methanol was added to the obtained reaction solution as a reaction terminator to stop the polymerization reaction, and then the solution was poured into methanol to precipitate the obtained polymer,
After separation and drying, 50 g of a white polymer was obtained. From the ¹ H-NMR spectrum, the obtained polymer was confirmed to be a block copolymer having 90 wt% of pt-butoxystyrene component and 10 wt% of m-t-butoxystyrene component. .

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₎

From the GPC elution curve (FIG. 1), it was confirmed that the copolymer was a monodisperse copolymer (M _W / M _n = 1.08). The number average molecular weight measured by the membrane osmometry was 23,000 g / mol.

EXAMPLE 2 A 2.2 liter flask was charged with 1.5 liters of tetrahydrofuran as a solvent and 1 × 10 ^-3 mol of cumylcesium as an initiator, mixed and cooled to -78 ° C., and then m-t-butoxystyrene. 20 g
Was added and a polymerization reaction was carried out while stirring for 3 hours. next,
When 20 g of pt-butoxystyrene was added and the polymerization reaction was carried out with stirring for 5 hours, the reaction solution turned red. Next, methanol was added to the reaction solution as a reaction terminator to stop the polymerization reaction, and then the solution was poured into methanol to precipitate the obtained polymer, which was separated and dried to obtain 40 g of a white polymer. Obtained.

From the ¹ H-NMR spectrum of the obtained polymer, characteristic absorption similar to that of Example 1 was observed, and 50% by weight of m-t-butoxystyrene portion and 50% by weight of pt-butoxystyrene portion were obtained. It was confirmed that the block copolymer had. Furthermore, from the GPC elution curve (FIG. 2), the obtained copolymer was a monodisperse copolymer (M _W / M
It was confirmed that _n = 1.05). The number average molecular weight of the copolymer measured by the membrane osmometry is 3
It was 8,000 g / mol.

[Brief description of drawings]

FIG. 1 shows the polymer obtained in Example 1 (number average molecular weight 2
(3,000 g / mol) is a GPC elution curve.

FIG. 2 shows the polymer obtained in Example 2 (number average molecular weight: 3).
8,000 g / mol) GPC elution curve.

Claims (4)

[Claims] 1. A monodisperse copolymer comprising a unit represented by the following chemical formula 1 and a unit represented by the following chemical formula 2. [Chemical 1] [Chemical 2] 2. The monodisperse copolymer according to claim 1, wherein the copolymer is a block copolymer of a repeating unit represented by the chemical formula 1 and a repeating unit represented by the chemical formula 2. 3. The method for producing a monodisperse copolymer according to claim 1, wherein the monomer represented by the following chemical formula 3 and the monomer represented by the following chemical formula 4 are anionically polymerized. [Chemical 3] [Chemical 4] 4. The method according to claim 3, wherein one monomer is polymerized and then the other monomer is added to polymerize.
The method for producing the monodisperse copolymer according to 1.