JPH022882B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has a weight average molecular weight _W and a number average molecular weight _N.
The present invention relates to a method for producing an isoprene polymer cyclized product having a dispersity defined by the ratio _W / _N of 2 or less. More specifically, the dispersity obtained by polymerizing isoprene monomer in the presence of an organometallic compound represented by the general formula RM (R represents an alkyl, aryl, or aralkyl group, and M represents lithium, sodium, or potassium) A small polymer of boron trifluoride ether complex and the general formula R′X
(R' represents a benzyl, t-butyl, or allyl group, and X represents a halogen.)
This is a method for producing the following isoprene polymer cyclized product. Cyclized products of natural rubber or synthetic rubber are most widely used as so-called negative resist materials, which are insoluble in solvents by crosslinking between polymer chains upon irradiation with light. Among the properties of resist materials, sensitivity and resolution are particularly important, but as the degree of integration of integrated circuits increases, the requirements for resolution have become stricter.
Materials that can handle microfabrication precision of 1 μm or less are required. However, the conventionally used rubber-based resist materials mentioned above have problems in terms of resolution and are not practical.
Accuracy of about 3 μm is said to be the limit, and it is difficult to support highly integrated circuit manufacturing processes that require dimensional accuracy of less than this. The present inventors have arrived at the present invention as a result of intensive research aimed at solving the problems seen in these conventional rubber-based resist materials, especially cyclized isoprene-based polymers. Conventional rubber-based resist materials, regardless of whether they are natural rubber or synthetic rubber, have a very wide molecular weight distribution, and the degree of dispersion defined by the ratio _W / _N of weight average molecular weight _W to number average molecular weight _N is It usually takes a value of 2 or 3 or more. The purpose of the present invention is to focus on the molecular weight distribution of these conventional rubber resist materials, and to
The objective is to produce a cyclized isoprene polymer with excellent resolution by cyclizing an isoprene polymer having a value close to , under conditions that do not disturb its molecular weight distribution. A feature of the present invention is that in the cyclization step of an isoprene-based polymer, cyclization can be achieved without substantially disturbing the molecular weight distribution of the polymer. Traditionally, methods for cyclizing diene polymers include (1) methods using sulfuric acid or sulfonic acids, (2) methods using Friedel-Crafts catalysts such as SnCl ₄ , TiCl ₄ , FeCl ₃
(3) A method using hydrogen halides such as hydrogen chloride, (4) A method using phosphorus compounds such as phosphorus pentachloride,
A method using phosphorus oxychloride or the like, and (5) a method using a cationic polymerization initiator such as a catalyst consisting of diethylaluminum chloride or ethylaluminum dichloride and trichloroacetic acid are known. However, in conventional methods, reactions between polymers such as gelation proceed, and it is difficult to selectively achieve intramolecular reactions. The inventors defined the isoprene monomer with the general formula
By living polymerization using an organometallic compound represented by RM (R represents an alkyl, aryl, or aralkyl group, and M represents lithium, sodium, or potassium) as an initiator,
A nearly monodisperse isoprene polymer with a degree of dispersion of 1.1 or less was obtained, and the polymer was treated with a boron trifluoride ether complex and the general formula R'X under mild conditions.
(R' represents a benzyl, t-butyl or allyl group, and X represents a halogen.) Isoprene polymer cyclized product whose dispersity is 2.0 or less when brought into contact with a catalyst consisting of an organic halide represented by found a way to manufacture it. Each step will be explained below. In the process of polymerizing isoprene monomer,
A living polymerization initiator with the general formula RM (R represents an alkyl, aryl or aralkyl group, M
indicates lithium, sodium or potassium. As the organometallic compound represented by ), for example, butyllithium, sodium phthalene, sodium anthracene, sodium biphenyl, phenylisopropyl potassium, α-methylstyrene tetramer potassium, etc. can be used, but butyllithium is preferable. It is. Also, the selection of polymerization welding is extremely important in relation to the microstructure of the diene polymer produced. For example, when n-butyllithium is used as an initiator, 1,4-addition polymers are almost selectively produced in hydrocarbon solvents such as hexane, cyclohexane, benzyl, toluene, and xylene; It is known that 1,2- or 3,4-addition polymers can be obtained using ether solvents such as dioxane. As the solvent used in the present invention, hydrocarbon solvents from which a 1,4-addition polymer of isoprene can be selectively obtained, such as hexane, cyclohexane, benzene, toluene, xylene, etc. can be used, but preferably benzene, Toluene and xylene. There is no need to particularly limit the molecular weight of the isoprene polymer of the present invention, but considering that the sensitivity of resist materials made from this polymer depends on the molecular weight, the molecular weight should be 10,000 or more, preferably
It is desirable to set the polymerization conditions so that the molecular weight is 20,000 or more. Next, as a catalyst used in the cyclization step, the cyclization reaction of the polymer proceeds even if only a boron trifluoride ether complex is used, but the reaction system has a general formula R'X (R' is benzyl,
It represents t-butyl or allyl group, and X represents halogen. ) The present cyclization reaction is significantly improved by coexisting an organic halide represented by the following formula. That is, when a catalyst consisting of the complex and an organic halide is used as compared to when the complex is used alone, the reaction time is shortened and the molecular weight distribution of the resulting polymer cyclized product is less disturbed. is suppressed. The organic halides used here include benzyl chloride, t-butyl chloride, allyl chloride,
Mention may be made of benzyl bromide, t-butyl bromide, allyl bromide, benzyl iodide, t-butyl iodide, and allyl iodide. As the solvent used in this step, aromatic hydrocarbons such as benzene, toluene, xylene, etc. can be used. The concentration of isoprene polymer in the cyclization step is
Although it depends on the molecular weight of the polymer, it is desirable that the amount is 0.5% by weight or more and 15% by weight or less, preferably 10% by weight or less. If it exceeds 15% by weight, gelation of the polymer will proceed during the reaction, which is not preferable. This reaction will proceed if the concentration of the boron trifluoride ether complex is 1 mol% or more of the number of moles of monomer units in the polymer, but from a practical standpoint, it should be 3% or more of the number of moles of monomer units in the polymer. is preferred. The organic halide used as a cocatalyst is 10 to 500 mol%, preferably 20 to 300 mol% of the chain. In addition, this reaction was carried out in the presence of a cocatalyst,
When producing the polymer cyclized product to a certain degree of cyclization, it is possible to reduce the amount of catalyst and shorten the reaction time compared to the case where boron trifluoride ether complex is used alone. The temperature at which the cyclization reaction is carried out is particularly important in relation to the molecular weight distribution of the resulting polymer cyclization product. That is, at temperatures below 10°C, intermolecular reactions and gelation reactions proceed, and at temperatures above 80°C, cyclized products with a wide molecular weight distribution are produced, which is undesirable. Therefore, the cyclization reaction is
It is desirable to carry out at a temperature of 10 to 80°C, preferably 20 to 60°C. In the cyclization reaction step, the reaction proceeds without any problem even if alcohols such as methanol, ethanol, etc. and phenol compounds such as BHT are contained in the reaction solution in an amount of 0.2% by weight or less. That is, without isolating and purifying the polymer obtained by living polymerization of isoprene monomer using benzene as a solvent in the polymerization process, a predetermined amount of the polymer is added to a solution containing a terminator such as methanol or ethanol to the polymerization reaction system. The above-mentioned cyclization reaction can be achieved without any problem even if a solution in which benzene is added and the concentration is adjusted is used. There is no need to particularly limit the cyclization rate of the polymer cyclide, but considering that the sensitivity of this resist material depends on the cyclization rate of the polymer cyclide, the cyclization rate should be between 40 and 90. %, preferably 50 to 80%. According to the present invention, a cyclized isoprene polymer having a narrow molecular weight distribution suitable as a raw material for a negative-tone photoresist in a process for manufacturing integrated circuits with a high degree of integration can be produced by a simple method under mild conditions. Next, the present invention will be explained in more detail with reference to Examples. Examples 1-3 52 g of strictly dehydrated isoprene monomer and 515 ml of benzene were mixed under a vacuum of 10 ⁻⁵ mmHg,
While stirring, add a predetermined amount of n-butyllithium hexane solution (concentration 0.165 mol/) (Example 1,
ml; Example 2, 4.45 ml; Example 3, 2.75 ml) was added dropwise at room temperature. After that, stirring was further performed for 3 hours, and after stopping the polymerization reaction solution by adding methanol in an amount 5 times the molar amount of the initiator, 5 parts by weight of a stabilizer (BHT) was added to 100 parts by weight of the polymerization reaction solution. . The microstructure of the obtained isoprene polymer is
Molecular weight was evaluated by NMR measurement, optical scattering measurement method, and molecular weight distribution was evaluated by ultracentrifugation velocity method. Add 80 ml of benzene to 20 ml of the polymerization reaction solution (polymer content: 2 g, converted to monomer unit: 2.94 mmol), and add 4 ml of a benzene solution of boron trifluoride ether complex (concentration: 0.44 mol/) at 25°C under a nitrogen stream.
(6 mol % per polymer monomer unit) and 0.163 g (1.76 mmol) of t-butyl chloride were added and stirred for 2 hours. The reaction solution was precipitated in methanol to obtain a powdery isoprene polymer cyclized product. The cyclization rate of the obtained isoprene polymer cyclized product was determined by NMR.
The molecular weight distribution was evaluated by ultracentrifugation velocity method. The results are shown in Table-1.

[Table] Comparative Examples 1 to 3 After adding methanol in an amount 5 times the molar amount of the initiator to a polymerization reaction solution polymerized by the same method as in Examples 1 to 3 to stop the polymerization, 100 weight of the polymer was added to the polymer solution. 5 parts by weight of BHT was added. Using a solution in which 80 ml of benzene was added to 20 ml of the polymer solution,
A cyclization reaction was carried out in the same manner as in Example 2, except that t-butyl chloride was not added and the amount of boron trifluoride ether complex added or reaction time was varied. The results are shown in Table-2.

[Table] Examples 4 to 9 Using the isoprene polymer solution obtained in the first reaction of Example 2 (Example 4, 40 ml; Example 5, 80 ml; Examples 6 to 9, 20 ml), (benzene addition amount : Example 4, 60ml; Example 5, 20ml; Examples 6-9, 80
ml) The cyclization reaction was carried out under various conditions. The boron trifluoride ether complex was added dropwise in an amount of 6 mol % per mol of monomer units of the polymer. The results are shown in Table-3.

[Table] Comparative Examples 4 and 5 The reaction was carried out in the same manner as in Example 8 or 9, except that t-butyl chloride was not added during the cyclization.
The results are shown in Table 4.

[Table] Examples 10 and 11 A cyclization reaction was carried out in exactly the same manner as in Example 2 except that another organic halide was used instead of chlorinated t-butyl. The results are shown in Table-5.

[Table] Comparative Examples 6 to 8 A cyclization reaction was carried out under the same conditions as in Example 2, except that the isoprene polymer solution used in Example 2 was used and the cyclization catalyst was changed. The results are shown in Table-6.

【table】

Claims (1)

[Claims] 1 The isoprene monomer has the general formula RM (R represents alkyl, aryl, or aralkyl, and M represents lithium, sodium, or potassium.)
The obtained polymer is polymerized in the presence of an organometallic compound represented by the formula R′X (R′ represents a benzyl, t-butyl or allyl group, and X represents a halogen). A method for producing an isoprene polymer cyclized product having a dispersity defined by the ratio w/n of weight average molecular weight w to number average molecular weight n of 2 or less by contacting with a catalyst made of an organic halide represented by