JPH1129617A - (meth)acrylic ester-based polymer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject low-viscosity new polymer useful as e.g. an ArF excimer laser resist material. SOLUTION: This new polymer bears, as branched polymer chain, a (meth) acrylic ester-based polymer composed of the essential structure unit of formula I [R1 is H or methyl; R3 is a (substituted) 7-15C alkyl] and structural unit(s) of formula II and/or formula III [R2 and R5 are each H or methyl; R4 is a (substituted) 1-12C alkyl, etc.]. This polymer is obtained by copolymerization between (meth)acrylic esters of formula IV and formula V through anionic polymerization process using an alkali metal or organoalkali metal as polymerization initiator followed by reaction of the resulting copolymer with a polyhalogen compound (e.g. a coupling agent having three or more halogen atoms). This polymer has a number - average molecular weight of 3,000-200,000, with a total number ratio of the structural unit of formula I to (structural unit of formula II + structural unit of formula III) being (1:9) to (9:1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a (meth) acrylate-based polymer, and more particularly, to a (meth) acrylate-based star polymer having a number average molecular weight of 3,000 to 200,000. And a (meth) acrylate polymer composition having the star polymer, and a method for producing the same.

[0002]

2. Description of the Related Art High integration of LSIs is progressing year by year, and at the same time, finer patterns are required. Photolithography technology using light exposure is used for microfabrication, and KrF excimer light is used for 256Mb DRAM which requires the 0.25 μm rule as the next generation technology.
1 Gb DRAM requiring 0.15 μm rule
Is promising for excimer lithography using ArF excimer light. As an ArF excimer laser resist material, a base resin having high transparency as a single-layer resist and excellent dry etching resistance is essential, and among them, an ester portion having an organic group containing a bulky alicyclic compound (meta ) (Meth) acrylate-based copolymers having an acrylate segment as an essential skeleton have attracted attention, and recently, those having further introduced (meth) acrylic acid segments to control alkali solubility have attracted attention. I have. It has been known that a high molecular weight polymer is more preferable as a resist material, particularly as a base polymer for a positive resist material, in terms of resolution, mechanical strength, and the like. The application of the resist on the substrate is usually performed by a spin coating method. However, when the molecular structure of the base polymer is changed to a linear structure to increase the molecular weight, there is a disadvantage that the viscosity of the resist increases and as a result, the spin coating becomes difficult.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to a (meth) acrylic ester-based star polymer having a lower viscosity than a polymer having a linear structure having the same molecular weight when prepared as a solution, and a (meth) -containing star polymer. An object of the present invention is to provide an acrylate polymer composition and a method for producing the same.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the living anion polymerization method has an organic group containing a bulky alicyclic compound (meth) in the ester portion. After copolymerizing (meth) acrylic esters with acrylic ester as an essential component, a coupling reaction is carried out using a specific polyhalogen compound to obtain a (meth) acrylic ester-based star polymer, The present inventors have found that a (meth) acrylic acid ester-based polymer composition can be obtained and completed the present invention.

The present invention relates to a compound represented by the general formula (I):

[0006]

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(R ₁ represents a hydrogen atom or a methyl group,
R ₃ represents an alicyclic group having 7 to 15 carbon atoms which may have a substituent or an alkyl group having the alicyclic group. The structural unit represented by) is an essential constituent unit, and this and the general formula (I
I) and / or general formula (III)

[0008]

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[0009]

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(R ₂ and R ₅ each independently represent a hydrogen atom or a methyl group, and R ₄ represents an alkyl group having 1 to 12 carbon atoms which may have a substituent; (Meth) acrylic ester-based copolymer consisting of a structural unit represented by the following formula (1), which has an alicyclic group or a heterocyclic group having 3 to 6 carbon atoms: The molecular weight is 3000-200000, and the total number of the structural units of the general formula (I) and [the structural units of the general formula (II) + the general formula (III)
Is a star polymer whose ratio to the total number of structural units is 1/9 to 9/1.

[0011] The present invention also provides a (meth) acrylic acid-based polymer composition containing one or more of the star polymers.

Further, an anion polymerization method using an alkali metal or an organic alkali metal as a polymerization initiator is carried out to obtain a compound represented by the general formula (IV):

[0013]

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(R ₁ represents a hydrogen atom or a methyl group;
R ₃ represents an alicyclic group having 7 to 15 carbon atoms which may have a substituent, or an alkyl group having the alicyclic group. (Meth) acrylic acid ester represented by the general formula (V)

[0015]

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(R ₂ independently represents a hydrogen atom or a methyl group, and R ₄ has 1 to 5 carbon atoms which may have a substituent.
12 alkyl groups, 3 to 6 carbon atoms which may have a substituent
Represents an alicyclic group or a heterocyclic group. 2. The method for producing a star polymer according to claim 1, wherein the (meth) acrylic acid ester represented by the formula) is copolymerized and then reacted with a polyhalogen compound.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the (meth) acrylate represented by the general formula (IV) includes 1-adamantyl acrylate, 1-adamantyl methacrylate, 2-methyl-2-adamantyl acrylate,
-Methyl-2-adamantyl methacrylate, 1-methylene adamantyl acrylate, 1-methylene adamantyl methacrylate, 1-ethylene adamantyl acrylate, 1-ethylene adamantyl methacrylate,
3,7-dimethyl-1-adamantyl acrylate,
3,7-dimethyl-1-adamantyl methacrylate,
Isobornyl acrylate, isobornyl methacrylate, tricyclodecanyl acrylate, tricyclodecanyl methacrylate, norbornane acrylate, norbornane methacrylate, menthyl acrylate, menthyl methacrylate and the like are exemplified, and these may be used alone or as a mixture of two or more. used.

In the present invention, the (meth) acrylate represented by the general formula (V) has 1 to 1 carbon atoms.
Examples of the (meth) acrylate having an alkyl group of 2 include methyl acrylate, methyl methacrylate,
Ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate,
n-butyl acrylate, n-butyl methacrylate,
t-butyl acrylate, t-butyl methacrylate,
2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isodecyl acrylate, isodecyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, lauryl methacrylate, etc. are exemplified, and an alicyclic group or heterocyclic group having 3 to 7 carbon atoms. Examples of the (meth) acrylic acid ester having the following are cyclohexyl acrylate, cyclohexyl methacrylate, tetrahydrofuranyl acrylate,
Examples thereof include tetrahydrofuranyl methacrylate, tetrahydropyranyl acrylate, tetrahydropyranyl methacrylate, 3-oxocyclohexyl acrylate, and 3-oxocyclohexyl methacrylate, and these are used alone or as a mixture of two or more.

In the present invention, the method for producing the copolymer constituting the branched chain of the star polymer is carried out by using the above-mentioned (meth) acrylic acid esters by using n-butyl lithium, s-butyl lithium, t-butyl lithium, ethyl The reaction is carried out by an anionic polymerization method using an organic alkali metal such as lithium, ethyl sodium, 1,1-diphenylhexyllithium, 1,1-diphenyl-3-methylpentyllithium as a polymerization initiator. -100 in an organic solvent under an inert gas atmosphere such as
By carrying out the polymerization reaction at a temperature of from 50 ° C to 50 ° C, preferably from -70 ° C to 0 ° C, a copolymer having a controlled structure and a narrow molecular weight distribution can be obtained.

Examples of the organic solvent include aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and cyclopentane; aromatic hydrocarbons such as benzene and toluene; diethyl ether; In addition to ethers such as tetrahydrofuran and dioxane, they are used as one or a mixture of two or more organic solvents usually used in anionic polymerization such as anisole and hexamethylphosphoramide.

The form of the copolymer can be selected from a random copolymer in which each component is statistically distributed over the entire copolymer chain and a partial block copolymer by selecting the method of adding the (meth) acrylic ester. A united or complete block copolymer is synthesized.

For example, a random copolymer is obtained by adding a mixture of the compound represented by the general formula (IV) and the compound represented by the general formula (V) to a reaction system and polymerizing the mixture.
Either one of them is preliminarily polymerized, and then the other mixture is added to continue the polymerization, or a part of one of them is preliminarily polymerized, and then the mixture of both is added to carry out the polymerization. By continuing the polymerization, the partial block copolymer is completely formed by sequentially adding the compound represented by the general formula (IV) and the compound represented by the general formula (V) to the reaction system and performing polymerization. A block copolymer is produced.

The reaction for forming a star polymer by using the copolymer thus obtained as a branched polymer chain is as follows:
After the completion of the copolymerization reaction, a polyhalogen compound having three or more halogen atoms is added to the reaction solution, and the reaction is achieved by performing a coupling reaction which also serves to stop the polymerization reaction. Examples of such polyhalogen compounds include tetrachlorosilane, trichloromethylsilane, tin tetrachloride, phosphorous trichloride, 1,2-bis (dichloromethylsilyl) ethane, 1,2,4,5-tetrakis (bromomethyl) benzene, 1,2,4,5-tetrakis (bromoethyl) benzene, 1,2,4,5-tetrakis (chloromethyl) benzene, 1,2,4,5-tetrakis (chloroethyl) benzene, 1,3,5-tris (Chloromethyl) benzene and the like are exemplified.

The number of branched chains in the star polymer is determined by the number of halogen atoms in the polyhalogen compound. Usually, a plurality of star chains having different degrees of branching are affected by the difference in reactivity between the living polymer terminal and each halogen atom. The polymer forms simultaneously. Therefore, the star polymer of the present invention preferably has three or more functional groups reacted, and includes not only a completely star polymer having all reacted. Further, the present invention also includes a composition of these star polymers and a copolymer having a linear structure formed by being killed by impurities in the system.

Among the star polymers of the present invention, those having 3 to 7 branched chains are particularly preferred because of their excellent performance as base polymers for resists.

The present invention also provides a (meth) acrylic acid-based polymer composition containing at least one of the star polymers, wherein the composition comprises a plurality of star polymers having different degrees of branching. A composition containing a star polymer or the like whose functional groups are partially unreacted may be used.

The introduction of the (meth) acrylic acid segment into the thus obtained star polymer or the (meth) acrylic ester-based polymer composition containing the star polymer may be carried out by using a solvent other than the solvent exemplified in the polymerization reaction. ,methanol,
In the presence of alcohols such as ethanol, ketones such as acetone and methyl ethyl ketone, cellosolves such as ethyl cellosolve, halogenated hydrocarbons such as carbon tetrachloride alone or in the presence of a mixture of two or more solvents, hydrochloric acid, An acidic reagent such as hydrogen chloride gas, sulfuric acid, hydrobromic acid, 1,1,1-trifluoroacetic acid, p-toluenesulfonic acid, or an alkaline reagent such as sodium hydroxide, ammonium hydroxide, and tetramethylammonium hydroxide. It is achieved by performing a hydrolysis reaction at room temperature to 150 ° C. as a catalyst. In this case, the (meth) acrylate represented by the general formula (IV) does not cause hydrolysis,
Only the (meth) acrylate skeleton represented by the general formula (V) is subject to hydrolysis. The degree of hydrolysis is adjusted by selecting the type of catalyst, the amount to be added, the reaction temperature, the reaction time, and the like, so that the required (meth) acrylic acid skeleton can be obtained.

[0028]

The present invention will be described in more detail with reference to Examples and Comparative Examples. However, the scope of the present invention is not limited by the following examples. In the examples, m represents the total number of the repeating units of the (meth) acrylate segment represented by the general formula (I), and n represents the total number of the repeating units of the (meth) acrylate segment represented by the general formula (II). And p indicates the total number of repeating units of the (meth) acrylic acid segment.

Example 1 In a nitrogen atmosphere, tetrahydrofuran (hereinafter referred to as TH)
20 mmol of s-butyllithium in 1000 g, and keeping the temperature at −60 ° C. with stirring, 1-adamantyl methacrylate (synthesized from 1-adamantanol and methacrylic acid chloride, purified purified product). 5
The mole was added dropwise over 30 minutes, and the reaction was continued for another hour, and completion of the reaction was confirmed by gas chromatography analysis (hereinafter abbreviated as GC). Next, 0.5 mol of t-butyl methacrylate was added dropwise over 30 minutes, and the reaction was continued for another hour, and the completion of the reaction was confirmed by GC. A part of the reaction solution was taken out of the system and measured by gel permeation chromatography (hereinafter abbreviated as GPC).
= 8900, peak top molecular weight (Mp) = 980
0, Mw / Mn = 1.15.
Next, 5 mmol of 1,2-bis (dichloromethylsilyl) ethane was added to the reaction solution, and a coupling reaction was performed for 30 minutes. A part of the reaction solution was taken out of the system and GP
As a result of measuring C, the polymer was a bimodal polymer having peaks at Mp = 29400 and 39200. For the polymer before and after the coupling reaction, ¹³ C NM
R (hereinafter abbreviated as NMR), m / n
= 25.1 / 25.3. From these facts, a methacrylate polymer composition containing a 3-branch and 4-branch star polymer having a branched chain of a block copolymer comprising a 1-adamantyl methacrylate skeleton and a t-butyl methacrylate skeleton is obtained. I confirmed that.

Example 2 Under a nitrogen atmosphere, 40 mmol of s-butyllithium was added to 1000 g of THF, and 0.8 mol of t-butyl methacrylate and 0.4 mol of methyl methacrylate were added while stirring and maintained at -60 ° C. 1-adamantyl methacrylate (as described above) was sequentially added to the reaction system in the order of 0.6 mol, each was dropped for 30 minutes to aging for 1 hour, and a copolymerization reaction was carried out while confirming the completion of the reaction by GC at each stage. A part of the reaction solution was taken out of the system and subjected to GPC measurement.
n = 7100, peak top molecular weight (Mp) = 800
0, Mw / Mn = 1.20.
Next, 10 mmol of 1,2,4,5-tetrakis (bromoethyl) benzene was added to the reaction system, and a coupling reaction was performed for 30 minutes. Then, the reaction solution was poured into a large amount of water to obtain a polymer. GPC measurement of this polymer showed that it was a bimodal polymer having peaks at Mp = 24000 and 32000. Next, 10 g of the obtained polymer was dissolved in propylene glycol monomethyl ether to form a 20% solution, 0.2 g of concentrated sulfuric acid was added, and the reaction was carried out at 70 ° C. for 1 hour. Then, the reaction solution was poured into a large amount of water. To precipitate the polymer, and after filtration and washing,
Drying at 5 ° C. for 5 hours gave 9.5 g of a white powdery polymer. As a result of measuring the polymer by GPC, the peak shape was the same as before hydrolysis, and Mp = 23100 and 31
It is a bimodal polymer having a peak at position 100. The composition ratio measured by ¹³ C NMR is m / n / p
= 15.1 / 17.4 / 13.0. From these facts, a methacrylate polymer composition containing a 3-branch and a 4-branch star polymer having a block copolymer comprising a 1-adamantyl methacrylate skeleton, a t-butyl methacrylate skeleton, and a methacrylic acid skeleton as branch chains. It was confirmed that a product was obtained.

[0031]

The present invention provides a (meth) acrylic ester-based star polymer having a lower viscosity than a linear polymer having the same molecular weight when a solution is formed, and a (meth) acrylic acid containing the star polymer. An ester polymer composition can be obtained. In particular, to obtain a branched polymer chain having a narrow molecular weight distribution and a star polymer that is a (meth) acrylate random copolymer having a controlled structure, or a block copolymer or a partial block copolymer. Can be. In particular, it can be expected to be used as an ArF excimer laser resist material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08F 293/00 C08F 293/00 C08L 33/00 C08L 33/00 53/00 53/00 (72) Inventor Hitoshi Matsumoto Chiba Pref. 12-54, Goi-Minamikaigan, Hara-shi Nippon Soda Functional Products Laboratory

Claims (9)

[Claims] 1. A compound of the general formula (I) (R ₁ represents a hydrogen atom or a methyl group, and R ₃ represents an alicyclic group having 7 to 15 carbon atoms which may have a substituent or an alkyl group having the alicyclic group.) A structural unit represented by the following formula is defined as an essential structural unit, and the structural unit is represented by the general formula (II) and / or the general formula (III). Embedded image (R ₂ and R ₅ each independently represent a hydrogen atom or a methyl group, and R ₄ represents an alkyl group having 1 to 12 carbon atoms which may have a substituent or a carbon atom which may have a substituent. (Alicyclic group or heterocyclic group represented by Formulas 3 to 6)) as a branched polymer chain, and a number average molecular weight of 3,000. ~ 2
00000 and the ratio of the total number of the structural units of the general formula (I) to the total number of [the structural units of the general formula (II) + the structural units of the general formula (III)] is 1/9 to 9/1. polymer. 2. The polymer according to claim 1, wherein the number of the branched polymer chains is 3-7.
The star polymer as described. 3. The star polymer according to claim 1, wherein the branched polymer chain is a random copolymer. 4. The star polymer according to claim 1, wherein the branched polymer chain is a block copolymer. 5. The star polymer according to claim 1, wherein the branched polymer chain is a partial block copolymer. 6. A composition comprising at least one of the star polymers according to claim 1. Description:
Acrylic acid polymer composition. 7. An anion polymerization method using an alkali metal or an organic alkali metal as a polymerization initiator by the general formula (IV): (R ₁ represents a hydrogen atom or a methyl group, and R ₃ represents an optionally substituted alicyclic group having 7 to 15 carbon atoms or an alkyl group having the alicyclic group. And a (meth) acrylate represented by the general formula (V): (R ₂ each independently represents a hydrogen atom or a methyl group;
₄ represents an alkyl group having 1 to 12 carbon atoms which may have a substituent, an alicyclic group or a heterocyclic group having 3 to 6 carbon atoms which may have a substituent. 2. The method for producing a star polymer according to claim 1, wherein the (meth) acrylic acid ester represented by the formula (1) is copolymerized and then reacted with a polyhalogen compound. 8. The polyhalogen compound has three halogen atoms.
The method for producing a star polymer according to claim 7, which is a coupling agent having the above. 9. The method according to claim 7, wherein a polymer obtained by reacting with a polyhalogen compound and terminating the polymerization is used to hydrolyze a part or all of R _{4 in} the polymer using an acidic reagent or an alkaline reagent. 2. The method for producing a star polymer according to claim 1, wherein the polymer is decomposed to introduce a (meth) acrylic acid skeleton into the copolymer.