JPS63277218A - Production of monodisperse polymer - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer having extremely narrow molecular weight distribution range in high yield and good reproducibility, by polymerizing alpha-cyanoacrylate with a specific monomer using a specific polymerization initiator at a specific reaction temperature. CONSTITUTION:alpha-cyanoacrylate is polymerized with a monomer expressed by the formula [X is CN, NO2, etc.; Y is CN, H, etc.; R is (halogenated) alkyl] while cooling to -120-20 deg.C in the presence of an anionic polymerization initiator consisting of a weak anion of organic amine, organic amide, phosphine, thiourea, thioalcohol, ether, etc., to provide the aimed polymer. As the monomer expressed by the formula, e.g. vinylidenecyanide is used. As the anionic polymerization initiator, e.g. diethylamine is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a monodisperse copolymer of α-cy, anoacrylic acid ester with good reproducibility. More specifically, the present invention features a radiation-sensitive resist material by polymerizing in a solvent at a specific reaction temperature using a specific polymerization initiator. The present invention provides a method for producing an α-cyanoacrylic acid ester copolymer having an extremely narrow molecular weight distribution and a value of approximately 1 (abbreviated as n) in good yield and with good reproducibility.

[Technical background of the invention]

A higher degree of integration is required in the manufacture of semiconductor large-scale 8I integrated circuits, and the line width is 0.5, which is the limit of optical exposure.
Electron beam direct writing, X-ray lithography, and exposure technology using focused ion beams have been proposed as sub-μ-level lithography technologies, and are being realized, but there are very few resists that can be put into practical use. .

These resist materials include negative type, which causes a crosslinking reaction by irradiation with radiation and becomes insoluble in the developer, and positive type, in which the main polymer of the resist causes a decomposition reaction and becomes easily soluble in the developer by irradiation with radiation. be.

Negative resists are characterized by high sensitivity and excellent etching resistance, but low resolution.

On the other hand, positive resists are characterized by high resolution but low sensitivity and poor etching resistance.

Recently, industrial demands for higher integration of large-scale integrated circuits have been increasing, and even negative resists with high sensitivity and excellent etching resistance can no longer meet the demand due to their inferior resolution, and positive resists have become mainstream. It's coming.

[Prior art and problems]

Conventionally, the main ingredients for positive radiation-sensitive resists are:
Polymethyl methacrylate (P-MMA) was the representative polymer. This P-MMA is an excellent resist that can provide a high resolution of about 0.3 to 0.5 microns, but its sensitivity to radiation is low and its sensitivity to electron beams is 5.
It is about X 10-'C/cl. In order to improve this low sensitivity, attempts have been made to introduce electron-withdrawing groups, and there are some resists that have achieved practical sensitivity.

However, the introduction of electron-withdrawing groups often leads to a decrease in etching resistance.

The resist based on α-cyanoacrylic acid ester has an electron-withdrawing group in the molecule, and has not only high radiation sensitivity but also high resolution (64 megabin l-D- As a resist for large-scale integrated circuits after RAM, it is essential to further improve sensitivity and resolution and to have stable practical performance.

Therefore, it is necessary to overcome this difficult problem by aiming at copolymerization with a monomer having better sensitivity characteristics to improve sensitivity, and by aiming at monodisperse polymers to improve resolution.

[Purpose of the invention]

The present invention is made by monodisperse copolymerizing monomers of the general formula (I) which have extremely excellent sensitivity to radiation and have very similar anionic polymerization behavior to α-cyanoacrylic acid esters. , for example, 64 megapith ID-
The object of the present invention is to provide a main polymer for a high-resolution, high-sensitivity positive-working radiation-sensitive resist suitable for large-scale integrated circuits after RAM.

[Structure of the invention]

That is, the present invention relates to α-cyanoacrylic acid ester and general formula (I) (wherein, X is CN, No□, COOR, and Y is CN).

While cooling one or more monomers from a group of monomers represented by +I, C0OR and R is an alkyl group or a halogenated alkyl group to 20 to -120°C, an organic amine,
organic amide, phosphine, thiourea, thioalcohol,
Polymerization in the presence of an anionic polymerization initiator obtained from weak anions such as ethers alone or by mixing them,
It is characterized by obtaining a monodisperse copolymer.

Regarding the polymerization method of α-cyanoacrylic acid ester, please refer to J.
, ^ppl, Po1yLSei, + Sat, 231 (I
There are radical polymerization methods and anionic polymerization methods, as described in 960), 1 Yu, 280 (1962). Regarding the anionic polymerizability of the 7-mer represented by -r formula (I), as described on page 67 of "Synthesis of Polymers" (1961 edition published by Kagaku Dojin), α-cyanacrylic acid ester It is known that the behavior is very similar to that of Therefore, in order to simplify the explanation of the anionic polymerizability of these seven polymers, these representative
The anionic polymerizability of α-cyanoacrylic acid ester will be described.

It is generally known that it is difficult to obtain polymers with an extremely narrow molecular weight distribution using radical polymerization methods.
Improving resolution has little effect.

On the other hand, it is known that the anionic polymerization method yields polymers with a very narrow molecular weight distribution, as typified by the anionic polymerization of styrene, p-dimethylaminomethylstyrene, isoprene, etc.; Due to the extremely high anionic polymerizability in anionic polymerization, it is extremely difficult to control the molecular weight and molecular weight distribution compared to the anionic polymerization of ordinary monomers, and the anionic polymerization method described in the above literature etc. A polymer having a predetermined molecular weight and molecular weight distribution cannot be produced with good reproducibility.

Further, even if attempts were made to produce this polymer by forcing it, many operational restrictions would be required on polymerization conditions, etc., and it would be impossible to obtain practical reproducibility.

-11. The fact that α-cyanoacrylic acid ester initiates polymerization even in the presence of a weak base such as water or alcohol is due to the fact that instant adhesives containing this as the main ingredient can be used in extremely small amounts on the surface of adherends. This is evident from the fact that it is prized as a liquid-based all-purpose adhesive due to its ability to instantaneously undergo anionic polymerization at room temperature using water as a curing agent.

Theoretically, there is no termination reaction in anionic polymerization, so the amount of polymerization initiator should be adjusted to tI! Although it is possible to obtain a polymer with a predetermined molecular weight and extremely narrow molecular weight distribution (theoretically, the same molecular weight) by separating the polymers, side reactions such as termination reactions caused by impurities often occur simultaneously. .

When a weak base such as water or alcohol is used as an anionic polymerization initiator for α-cyanoacrylic acid ester,
Its polymerization rate is extremely slow, and it can be used when handling extremely small amounts of monomers, such as in instant adhesives, but this polymerization reaction is easily affected by trace impurities and has poor productivity, making it unsuitable as an industrial manufacturing method. be.

On the other hand, when phosphines and amines, which are more nucleophilic and highly basic, are used as polymerization initiators, the polymerization rate is extremely fast under normal conditions, causing runaway reactions and side reactions.
The molecular weight and molecular weight distribution of the produced polymer cannot be easily controlled.

In addition, acidic substances such as sulfur dioxide and propanezalton are usually added to α-cyanoacrylic ester as polymerization inhibitors, and these maintain the storage stability of α-cyanoacrylic ester. However, it is clear that the simultaneous occurrence of termination reactions due to these influences the growth reaction of polymerization.

The present inventors have focused on the specific anionic polymerizability of the above-mentioned α-cyanoacrylic acid ester, and provide a method for producing a polymer useful as a positive resist material having high sensitivity and excellent resolution. As a result of various studies on the polymerization method of α-cyanoacrylic acid ester with the main purpose of and suppress the molecular movement,
A-type amide, which is more active than extremely weak anions such as water,
Phosphine, active amine, thiourea, thioalcohol,
By polymerizing in the presence of a polymerization initiator such as ether, side reactions caused by water and other impurities in the system, and polymerization termination reactions caused by acidic substances such as sulfur dioxide and propane sultone can be suppressed. They discovered a method for producing monodispersed polymers with excellent properties and completed the present invention.

The present invention will be explained in more detail below.

Specific examples of the monomer represented by the general formula (I) used in the present invention include vinylidene anide, nitroethylene, diethyl methylene malonate, etc., and the corresponding α-cyanoacrylate ester is as follows. It is expressed by a general formula.

N 1 (YoC=C-C0OR However, in the formula, R is an alkyl group, a halogenated alkyl group, a cycloalkyl group, an alkenyl group, an alkoxyalkyl group, an alkynyl group, an allyl group, etc. having a carbon number of 1 to 12. Yes, specifically methyl α-cyanoacrylate, ethyl α-cyanoacrylate, n-propyl α-cyanoacrylate, isoproyl α-cyanoacrylate, n-butyl α-cyanoacrylate, α-cyanoacrylate. Isobutyl, n-pentyl α-cyanoacrylate, isoamyl α-cyanoacrylate, n-hexyl α-cyanoacrylate, Hn-octyl α-cyanoacrylate, cyclohexyl α-cyanoacrylate, 2-ethylhexyl α-cyanoacrylate , α-allyl cyanoacrylate, benzyl α-cyanoacrylate, 2-methoxyethyl α-cyanoacrylate, propargyl α-cyanoacrylate, trichloroethyl α-cyanoacrylate, α
-tetrachloroproyl cyanoacrylate, trifluoroethyl α-cyanoacrylate, phenyl α-cyanoacrylate, and the like.

All of these can be obtained by ordinary synthetic methods,
It is sufficient that it contains an anionic polymerization inhibitor of 5 to 501+1)I+ and a radical polymerization inhibitor of 2.000 ppm or less. In the production method of the present invention, a specific anionic polymerization initiator and control of the reaction temperature are essential conditions. The polymerization initiator is a weak anion such as organic amine, organic amide, phosphine, thiourea, thioalcohol, ether, or a mixture thereof, preferably diethylamine, dimethyl baro-toluidine, aniline, dimethylformamide, diphenyl. They include phosphine, 2,5-xylidine, thiosemicarbazide, thiourea, 1,3-diphenylthiourea, 1-propanethiol, 15 crown 5 ether, and the like.

The amount of these polymerization initiators added is not limited to the amount, but is preferably 0.01 to 2.0 mol % based on the monomer.

The reaction temperature is preferably near or below the freezing point of each monomer. The purpose of this low-temperature polymerization reaction is to minimize the molecular movement of the seven polymers, use a relatively active initiator, and suppress side reactions caused by trace impurities. Usable reaction temperature is 20~
-120°C, preferably -30 to -100°C
'C.

Solvents used for this purpose include acetone, methyl ethyl ketone, ethyl acetate, cyclohexanone, methyl isobutyl ketone, acetonitrile, propionitrile,
Trichlorethylene, T)! In addition to F, etc., these solvents are mixed solvents.

In any case, the solvent used is a good solvent for the homopolymer, copolymer, and copolymer of the general formula (■) and the copolymer with α-cyanoacrylic acid ester, and the general formula (I) is The solvent must not precipitate homopolymers, copolymers, and copolymers with α-cyanoacrylic acid ester.

These solvents can be purified by known dehydration methods.

As described above, by the method for producing monodisperse polymers of homopolymers, copolymers, and copolymers with α-cyanoacrylic acid esters of the general formula <1), monodisperse polymers with an arbitrary molecular weight of 20,000 to 1,000,000 are produced. Polymers can be obtained with good reproducibility and good yields.

As a means for implementing the polymerization method of the present invention, a predetermined amount of a predetermined solvent is introduced into a polymerization container, then a predetermined amount of a predetermined polymerization initiator is added, and the container is cooled to a predetermined temperature.

While thoroughly stirring this polymerization initiator solution, a predetermined amount of a predetermined solvent containing a predetermined amount of the monomer of general formula (I) is added at a predetermined temperature to conduct a polymerization reaction (in the case of homopolymerization), and in the case of copolymerization, this A predetermined amount of a predetermined solvent containing a predetermined amount of a predetermined 7-mer was further added to the thus-obtained orping polymer for block polymerization, and the reaction was terminated with a polymerization terminator. However, this order is not particularly limited.

The method of the present invention is applicable regardless of the scale of the polymerization.

(Effects of the Invention) The present invention uses a specific anionic polymerization initiator, a specific temperature, and a specific solvent to monodisperse α-cyanoacrylic acid ester and a highly anionically polymerizable monomer of general formula (I). It provides a method for economically and efficiently obtaining a copolymer, and a resist based on this polymer is D-
As a RAM, for example, it is used for electron beam or X-ray lithography in the manufacture of semiconductor large-scale integrated circuits of 64 megabits or higher, and greatly contributes to the improvement of semiconductor technology and its economic efficiency.

Example 1 An 800 m+1 toluene solution containing 5×10 −′ moles of diethylamine as a polymerization initiator was introduced into a flask,
The flask was cooled to -55°C.

While thoroughly stirring this solution, add 15 ml of a toluene solution containing 0.1 mol of diethyl methylenemalonate.
After polymerization by sequentially introducing the polymer at a temperature not exceeding 5°C, an anionic polymerization terminator was added and the polymer was purified by reprecipitation method, followed by gel permeation chromatography (c
When the molecular weight was measured by a pc)-light scattering method, the molecular weight was 370,000 and the dispersity was 1.04.

Examples 2 to 6 A predetermined amount of a predetermined polymerization initiator was added to 700 ml of a predetermined polymerization solvent, and the mixture was cooled to an internal temperature of -40 to -80°C. While thoroughly stirring this polymerization initiator solution, 100 ml of a predetermined polymerization solvent containing a predetermined amount of a predetermined monomer of the predetermined general formula (I) including an anionic polymerization inhibitor SSO 450 pp+ is sequentially introduced without exceeding a predetermined temperature to cause polymerization. , 100 m of a predetermined polymerization solvent containing a predetermined amount of a predetermined α-cyanoacrylic acid ester monomer containing an anionic polymerization inhibitor SO□50 ppm in the thus obtained or ping polymer!
The copolymer was purified by the reprecipitation method and the copolymer was obtained by terminating the polymerization reaction with an anionic polymerization terminator. The molecular weight was measured by GPC-light scattering method and the results shown in Table 1 were obtained. (Space below) Table 1 Total number of moles of ゜-cyanoacrylic ester and monomer of general formula ([) charged: 0.1 mol (α-cyanoacrylic ester/monomer of general formula (I) - 0.07 mol) 1
0.03 mol) Amount of anionic polymerization initiator: 5X10
-' moles Charged monomer/charged anionic polymerization initiator (mole ratio) 2.0Of): 1 Comparative Examples 1 to 4 700ym containing 5XIQ-' moles of predetermined polymerization initiator
Introduce 1 of acetone toluene mixed solution into the flask,
The temperature inside the system was maintained at 30"C. While sufficiently stirring, an acetone/toluene mixed solvent containing 3 mol of diethyl methylene malonate containing 50 ppm of an anionic polymerization inhibitor was sequentially introduced into the system and polymerized. After that, 50 ppm of anionic polymerization inhibitor S08 was added to this living polymer.
100 ml of an acetone/toluene mixed solvent containing 0.07 mol of ethyl α-cyanoacrylate was sequentially introduced with sufficient stirring to polymerize, and a polymerization terminator was added to stop the polymerization to obtain a copolymer. .

After purifying this copolymer by reprecipitation method, the molecular weight was measured by GPC-light scattering method, and the results shown in Table 2 were obtained.

This result shows that a monodisperse polymer cannot be obtained at a reaction temperature of 30"C.Table 2 (bottom margin of 321)

Claims (1)

[Claims] General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, in the formula, X is CN, NO_2, COOR, Y is CN, H, COOR, R is an alkyl group, halogenated Alkyl group) monomer alone or one or more of these monomer groups and α-cyanoacrylic acid ester are cooled to 20 to -120°C while organic amine, organic amide, phosphine, thiourea, thioalcohol. , a method of producing a monodisperse polymer by polymerizing in the presence of an anionic polymerization initiator obtained singly or by mixing two or more of weak anions such as ether.