JP2006219677A - Copolymer and resist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolymer having excellent adhesion to high polarity surfaces such as a surface of a metal, excellent in hydrophobicity and heat resistance and having good solubility in a solvent for resists, and to provide a resist composition containing the copolymer. <P>SOLUTION: The copolymer obtained by polymerizing a monomer having an alicyclic skeleton, a monomer having a lactone skeleton, and a vinyl-based monomer having a polarity higher than that of the monomer having an alicyclic skeleton and lower than that of the monomer having a lactone skeleton. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is excellent in adhesion to a highly polar surface such as a metal surface, can effectively impart hydrophobicity and heat resistance, has good solubility in a solvent, and has a low insoluble content. And a resist composition using the copolymer.

  Conventionally, it is known that a highly polar compound such as a metal surface has good adhesion due to electrostatic interaction. On the other hand, it is known that a compound having low polarity is excellent with respect to hydrophobicity, and a cyclic compound is excellent with respect to heat resistance.

  Therefore, in order to obtain a coating material that is excellent in adhesion to a highly polar surface such as a metal surface and can effectively impart hydrophobicity and heat resistance, it has a highly polar monomer and a low polarity cyclic structure. It has been proposed to use a binary copolymer obtained by copolymerizing a monomer as a resin composition for a coating material.

  However, in the case of copolymerizing monomers having such polarities that are greatly different and one of them has a large cyclic skeleton, since the polymerization reactivity thereof is greatly different, it is difficult to randomly copolymerize, in the early and late stages of polymerization. There is a tendency to produce a copolymer in which one monomer component is very much copolymerized. Therefore, when this copolymer is dissolved in a solvent so as to be used as a solvent-based paint or resist composition, the solubility of some of the copolymers with greatly deviated monomer components is poor. Has occurred. And this solvent insoluble matter was the cause of filter clogging in the filtration process of paints and the like, and appearance defects such as coating films.

  Therefore, the problem in the present invention is to have a highly polar monomer excellent in adhesion to a highly polar surface such as a metal surface and a low polarity cyclic structure that can effectively impart hydrophobicity and heat resistance. To provide a copolymer obtained by copolymerizing a monomer, having a good solubility in a solvent and having no insoluble content, and a resist composition using the copolymer. is there.

  In view of the above problems, the present inventors have conducted extensive studies on the solubility of the copolymer. As a result, in the copolymer obtained from a monomer having a cyclic structure with low polarity and a monomer having high polarity, (1 ) Keep the copolymer composition of the highly polar monomer that has been varied for each copolymer chain within a specific range before and after the average copolymer composition of the highly polar monomer in the entire copolymer. (2) Copolymerization by adding a monomer having a specific polarity; (3) By producing by a specific polymerization method, the solubility in solvents for paints and resists is good, and insoluble matter The present invention has been found to be a suitable copolymer which is not present.

  That is, the copolymer of the present invention is a copolymer obtained by polymerizing a monomer having an alicyclic skeleton, a monomer having a lactone skeleton, and another vinyl monomer. The other vinyl monomer has a higher polarity than the monomer having the alicyclic skeleton and a lower polarity than the monomer having the lactone skeleton.

  The copolymer of the present invention is obtained by polymerizing a monomer having an alicyclic skeleton, a (meth) acrylate having a substituted or unsubstituted γ-butyrolactone ring, and another vinyl monomer. It is characterized by being obtained.

  The resist composition of the present invention comprises the copolymer of the present invention.

  The copolymer of the present invention is excellent in adhesion to a highly polar surface such as a metal surface, hydrophobicity and heat resistance, and has good solubility in a resist solvent.

  Further, the resist composition of the present invention has high uniformity and is excellent in terms of sensitivity and resolution.

The present invention will be described in detail below.
The present invention relates to a copolymer obtained by polymerizing at least a monomer having an alicyclic skeleton and a monomer having a lactone skeleton.

A monomer having an alicyclic skeleton imparts hydrophobicity and heat resistance to a copolymer obtained by polymerizing the monomer and its resist composition.
Although it does not specifically limit as a monomer which has such an alicyclic skeleton, A cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopenta Dienyl (meth) acrylate and at least one selected from the group consisting of these substituents are preferably used because of their excellent hydrophobicity and heat resistance. Specific examples include 1-isobornyl methacrylate, 2-methacryloyloxy-2-methyladamantane, cyclohexyl methacrylate, adamantyl methacrylate, tricyclodecanyl methacrylate, and dicyclopentadienyl methacrylate. These can be used alone or in combination of two or more as required.

  Moreover, it is preferable that the monomer which has alicyclic skeleton is used in the range of 10-90 mol% with respect to the whole monomer component, More preferably, it is the range of 40-60 mol%. The more the monomer having an alicyclic skeleton, the higher the hydrophobicity and heat resistance of the resulting copolymer and its resist composition, and the smaller the monomer, the better the adhesion by the monomer having a lactone skeleton described later. Becomes prominent.

A monomer having a lactone skeleton imparts adhesion to a highly polar surface such as a metal surface to a copolymer obtained by polymerizing the monomer and its resist composition.
The monomer having such a lactone skeleton is not particularly limited, but a (meth) acrylate having a substituted or unsubstituted δ-valerolactone ring, a monomer having a substituted or unsubstituted γ-butyrolactone ring At least one selected from the group consisting of is preferably used because of its excellent adhesion, and in particular, a monomer having an unsubstituted γ-butyrolactone ring is preferably used. Specifically, β-methacryloyloxy-β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-butyrolactone, β-methacryloyloxy-γ-butyrolactone, β-methacryloyloxy-β-methyl -Γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone, 2- (1-methacryloyloxy) ethyl-4-butanolide, pantoyllactone methacrylate and the like. Examples of the monomer having a similar structure include methacryloyloxy succinic anhydride. These can be used alone or in combination of two or more as required.

  Moreover, it is preferable that the monomer which has the said lactone skeleton is used in the range of 10-90 mol% with respect to the whole monomer component, More preferably, it is the range of 40-60 mol%. The more the monomer having a lactone skeleton, the better the adhesion of the resulting copolymer and its resist composition, and the less the monomer, the more effective the hydrophobicity and heat resistance of the monomer having an alicyclic skeleton. become.

In the present invention, in addition to the monomer having an alicyclic skeleton and the monomer having a lactone skeleton, a vinyl monomer copolymerizable with these monomers (hereinafter referred to as other vinyl monomer). May be used.
Other vinyl monomers include, for example, (meth) acrylic acid esters having a linear or branched skeleton structure, specifically methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , N-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (Meth) acrylate, n-propoxyethyl (meth) acrylate, i-propoxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, i-butoxyethyl (meth) acrylate, t-butoxyethyl (meth) acrylate, etc. (Meth) acrylic acid ester Aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and maleic anhydride; acrylamide and chloride Examples include vinyl and ethylene. These may be used alone or in combination of two or more as required.
Other vinyl monomers can be used as long as the adhesion, water resistance and heat resistance of the resulting copolymer are not impaired, and are preferably used at 40 mol% or less based on the entire monomer components. .

In the present invention, the copolymer composition distribution of the monomer having a lactone skeleton in the copolymer is within -10 to +10 mol% of the average copolymer composition (X, unit mol%) of the monomer having a lactone skeleton. That is, it is preferably within (X-10) to (X + 10) mol%. If the copolymer composition distribution of the monomer having a lactone skeleton in the copolymer exceeds this range, the solubility in a solvent for resist deteriorates and the insoluble matter increases, which is not preferable.
Moreover, the resist composition for semiconductor manufacture using the copolymer in which the copolymer composition distribution of the monomer having a lactone skeleton is within −10 to +10 mol% of the average copolymer composition has high uniformity. Therefore, the sensitivity and resolution as a resist are high and excellent.

  When this copolymer is used as a resist composition for semiconductor production, the average copolymer composition of monomers having a lactone skeleton is preferably 40 to 60 mol%. As the average copolymer composition is larger, the adhesion to the substrate surface is improved and the resolution as a resist is improved, and as the average copolymer composition is smaller, the content of the monomer having an alicyclic skeleton is relatively increased. The dry etching resistance is improved.

The reason why the copolymer having a lactone skeleton having a copolymer composition distribution within −10 to +10 mol% of the average copolymer composition has good solubility is considered as follows.
A monomer having an alicyclic skeleton and a monomer having a lactone skeleton having greatly different polarities are usually difficult to copolymerize randomly because the polymerization reactivity of each monomer is greatly different. In particular, in batch polymerization, the copolymer composition of the monomers in the copolymer obtained at the early and late stages of polymerization (that is, depending on the polymerization rate) is greatly biased. On the other hand, the solvent used for the resist composition is selected according to the average composition ratio of the monomers charged at the time of copolymer synthesis. For this reason, it is presumed that a copolymer having a greatly biased copolymer composition of the monomer has poor solubility in the solvent.

The average copolymer composition value of the monomer having a lactone skeleton of the entire copolymer in the present invention is determined by measuring ¹ H-NMR of the copolymer and calculating the average copolymer from the ratio of the specific ¹ H signal intensity obtained. Obtained by calculating the composition. The average copolymer composition obtained by the above ¹ H-NMR measurement almost coincides with the proportion of the monomer charged at the time of producing the copolymer.

The copolymer composition distribution of the monomer having a lactone skeleton in the copolymer in the present invention is obtained by the above ¹ H-NMR measurement of the copolymer composition of the monomer having a lactone skeleton for each copolymer chain. It shows how much the average copolymer composition varies.
The copolymer composition distribution of the monomer having a lactone skeleton in the copolymer of the present invention is obtained by dividing the copolymer solution into 10 to several tens of fractions by gel permeation chromatography (GPC). Each fraction is measured by measuring ¹ H-NMR and determining the copolymer composition of the monomer having a lactone skeleton in each fraction.

  As described above, the copolymer of the present invention is a copolymer obtained by adding another vinyl monomer to a monomer having an alicyclic skeleton and a monomer having a lactone skeleton. There may be. In this case, other vinyl monomers have a higher polarity than monomers having an alicyclic skeleton, and vinyl monomers having a lower polarity than monomers having a lactone skeleton (hereinafter referred to as intermediate Other vinyl monomers having the following polarity are preferred. By copolymerizing a monomer having an alicyclic skeleton, a monomer having a lactone skeleton, and another vinyl monomer having an intermediate polarity, a copolymer obtained in the early and late stages of polymerization is obtained. The bias of the monomer component in the polymer can be reduced. Thereby, the solubility of the copolymer is improved, and the insoluble content in the solvent can be reduced.

  Examples of such other vinyl monomers having an intermediate polarity include (meth) acrylic acid esters having a linear or branched skeleton structure, specifically, methyl (meth) acrylate, ethyl (Meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, methoxyethyl (meth) Acrylate, ethoxyethyl (meth) acrylate, n-propoxyethyl (meth) acrylate, i-propoxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, i-butoxyethyl (meth) acrylate, t-butoxyethyl ( And (meth) acrylate. These can be used alone or in combination of two or more as required.

  Such other vinyl monomers having an intermediate polarity are preferably used in an amount of 0 to 40 mol% based on the entire monomer components. The more the other vinyl monomers having intermediate polarity, the higher the solubility of the obtained copolymer, so the insoluble content decreases, and the smaller the amount, the lower the adhesiveness, water resistance, and heat resistance of the resulting copolymer. Becomes higher.

  Here, the polarity of the monomer is defined by Polymer Handbook Third Edition Ed. By J. Brandrup and EH Immergut (John Wiley & Sons Inc., 1989) 7 section 519-544. It is defined by the numerical value of the polar term (hereinafter referred to as δP value) in the formula of the solubility parameter of the liquid represented by the sum of the hydrogen bond terms. This δP value generally tends to increase in the order of those having an alicyclic skeleton structure, those having a linear or branched skeleton structure, and those having a lactone skeleton.

In the case of using another vinyl monomer having an intermediate polarity, the monomer having an alicyclic skeleton is preferably in the range of 10 to 90 mol% with respect to the entire monomer component. The greater the number of monomers having an alicyclic skeleton, the greater the hydrophobicity and heat resistance of the resulting copolymer and its resist composition. The smaller the number, the greater the effect of improving adhesion by the monomer having a lactone skeleton. Become.
Moreover, when using the other vinyl-type monomer which has intermediate polarity, the monomer which has lactone skeleton has the preferable range of 10-90 mol% with respect to the whole monomer component. The more the monomer having a lactone skeleton, the better the adhesion of the resulting copolymer and its resist composition, and the less the monomer, the more effective the hydrophobicity and heat resistance of the monomer having an alicyclic skeleton. become.

  When the copolymer of the present invention is used as a resist composition for semiconductor production, the weight average molecular weight is more preferably 1,000 to 20,000. The smaller the weight average molecular weight, the higher the sensitivity and resolution as a resist. Further, a narrow molecular weight distribution is more preferable because sensitivity and resolution as a resist are improved. Specifically, the value of weight average molecular weight / number average molecular weight is preferably 1.0 to 1.5.

The copolymer of the present invention is produced by a known polymerization method such as a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, or a bulk polymerization method. Among these, the solution polymerization method is preferable in consideration of the molecular weight of the obtained copolymer.
Usually, a copolymer is produced by a solution polymerization method in which a monomer component having an alicyclic skeleton and a monomer having a lactone skeleton, and in some cases, other vinyl monomers are added. It is carried out by dissolving in an organic solvent, adding a polymerization initiator to this, and heating and stirring for a certain time.

  In particular, as a method for producing the copolymer of the present invention, all monomer components including a monomer having an alicyclic skeleton and a monomer having a lactone skeleton in advance and a polymerization initiator are used as an organic solvent. A method of dropping the dissolved mixed solution into an organic solvent maintained at a constant temperature, so-called dropping polymerization method, is preferable because the copolymer composition obtained at the initial stage and the latter stage of polymerization does not largely deviate.

  The polymerization initiator used in the dropping polymerization method is not particularly limited as long as it efficiently generates radicals by heat. Examples of such a polymerization initiator include azo compounds such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), and organic peroxides such as benzoyl peroxide. It is done.

  The solvent used in the dropping polymerization method and the solvent to be dropped are a copolymerizable monomer having an alicyclic skeleton, a copolymerizable monomer having a lactone skeleton, a polymerization initiator, and a copolymer to be obtained Any of these solvents is not particularly limited as long as it can be dissolved. Examples of such solvents include alcohols such as isopropyl alcohol and butyl alcohol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and isobutyl acetate; cellosolves such as ethyl cellosolve and butyl cellosolve; Examples include ethers such as 1,4-dioxane and tetrahydrofuran.

The polymerization temperature in the dropping polymerization method is determined by the boiling point of the solvent used, the decomposition temperature of the polymerization initiator used, and the like, and is not particularly limited, but is preferably in the range of 50 to 150 ° C. The higher the polymerization temperature, the shorter the reaction time and the higher the productivity, and the lower the polymerization temperature, the easier the reaction control.
Although the dropping speed in the dropping polymerization method is not particularly limited, it is usually preferable to be a constant speed. Further, the dropping time is not particularly limited, but it is usually 6 hours or longer, and it is preferable to hold the temperature for about 2 hours after completion of the dropping to complete the polymerization.

  The copolymer solution produced by the above production method is diluted to a suitable solution viscosity with a good solvent such as tetrahydrofuran or 1,4-dioxane, and then dropped into a large amount of poor solvent such as methanol or water. To precipitate. Thereafter, the precipitate is filtered off and sufficiently dried. This process is called “reprecipitation” and may be unnecessary depending on circumstances, but is very effective for removing unreacted monomers remaining in the polymerization solution, a polymerization initiator or the like. If these unreacted substances remain as they are, there is a possibility of adversely affecting the storage stability and the appearance of the coating film after the resist is formed. Therefore, it is preferable to remove them if possible.

The copolymer of the present invention has an excellent light transmittance of 193 nm measured at a film thickness of 500 nm. For the ArF resist resin, a copolymer having a light transmittance of 60% or more is preferable, a copolymer of 70% or more is more preferable, and a copolymer of 75% or more is particularly preferable.
Thereafter, the dried copolymer powder is dissolved in a resist solvent. Although this solvent is arbitrarily selected according to the purpose, the copolymer having an alicyclic skeleton and a lactone skeleton as in the present invention is very difficult to select a solvent because their polarities are greatly different. The selection of the solvent is restricted by reasons other than the solubility of the resin, for example, the uniformity of the coating film, the appearance, or the safety.

  Examples of the solvent that satisfies the above conditions when the copolymer of the present invention is used as a resist composition include ethyl lactate, propylene glycol monomethyl ether acetate, cyclohexane, and diglyme.

  The resist composition of the present invention preferably contains a photoacid generator. There is no restriction | limiting in particular about the photoacid generator to be used, It can select arbitrarily from what can be used as a photoacid generator of a chemically amplified resist composition. Specific examples include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, and diazomethane compounds. Of these, onium salt compounds are preferred, and examples thereof include sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts. Specific examples include triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate. And diphenyliodonium hexafluoroantimonate.

  In this invention, a photo-acid generator can be used individually or in mixture of 2 or more types. The amount of the photoacid generator used in the present invention is appropriately selected depending on the type of the photoacid generator selected. -10 parts by weight. The larger the amount of photoacid generator used, the better the chemical reaction caused by the catalytic action of the acid generated by exposure, and the smaller the amount of photoacid generator, the more uneven coating occurs when applying the composition and the occurrence of scum during development. Less.

The resist composition of the present invention preferably contains a basic substance. As such a basic substance, a nitrogen-containing heterocyclic compound and / or an amide group-containing compound are particularly preferable.
Specific examples of nitrogen-containing heterocyclic compounds include imidazoles such as imidazole, benzimidazole, 4-methylimidazole, 4-methyl-2-phenylimidazole; pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine. In addition to pyridines such as 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, N-methyl-4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, quinoline, 8-oxyquinoline and acridine, pyrazine , Pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, morpholine, 4-methylmorpholine, piperazine, 1,4-dimethylpiperazine, tetrazole, 1,4-diazabicyclo [2.2.2] octane, and the like. . Of these, tetrazoles, diazabicyclooctanes, and piperidines are more preferable.

  Specific examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, N-cyclohexylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N- (1-adamantyl) Acetamide, propionamide, benzamide, N-acetylethanolamine, 1-acetyl-3-methylpiperidine, etc., or pyrrolidone, N-methylpyrrolidone, 1-cyclohexyl-2-pyrrolidone, ε-caprolactam, δ-valerolactam, 2 -Cyclic amides such as pyrrolidinone, or acrylamide, methacrylamide, t-butylacrylamide, N-isopropylmethacrylamide, methylenebisacrylamide, methylenebismethacrylamide, N-methylo Examples include acrylamides such as allyl acrylamide, N-methylol methacrylamide, N-methoxy acrylamide, N-ethoxy acrylamide, N-butoxy acrylamide, and diacetone acrylamide. Of these, (meth) acrylamides and acetamides are more preferable.

A basic substance can be used individually or in mixture of 2 or more types. Although the usage-amount of a basic substance is suitably selected from the kind of selected basic substance, it is 0.01-10 mol normally with respect to 1 mol of photoacid generators, Preferably it is 0.05-1. Is a mole. The larger the amount of the basic substance used, the better the resist shape, and the smaller the amount used, the higher the sensitivity as a resist and the developability of the exposed area.
Furthermore, the chemical amplification resist composition of the present invention may contain various additives such as a surfactant, a sensitizer, an antihalation agent, a storage stabilizer, and an antifoaming agent as necessary.

  Hereinafter, the present invention will be specifically described based on examples. Here, “parts” means “parts by weight” unless otherwise specified.

The physical properties of the copolymer were measured using the following method.
-Weight average molecular weight It calculated | required in conversion of the polymethylmethacrylate by gel permeation chromatography (GPC). Chloroform was used as the solvent.
-Average copolymer composition of monomers with lactone skeleton (mol%)
^It calculated | required by the measurement of < ¹ > H-NMR. Deuterated chloroform was used as the solvent.
-Copolymer composition distribution of monomer having lactone skeleton The copolymer is dissolved in chloroform, this solution is fractionated into 10 fractions by GPC, and ¹ H-NMR measurement is performed on each fraction. The copolymer composition of the monomer having a lactone skeleton in the polymer was determined. The one having the highest copolymer composition of the monomer having the lactone skeleton is the maximum composition (mol%), and the one having the lowest copolymer composition of the monomer having the lactone skeleton is the minimum composition (mol%). .

-Solubility 1 part of the copolymer was added to 7 parts of each of ethyl lactate and propylene glycol monomethyl ether acetate and stirred at room temperature for 2 hours, and the state of the solution was observed. In the determination, a case where there was no insoluble matter and the solution was transparent was evaluated as “◯”, and a case where there was an insoluble portion and the solution was opaque was evaluated as “X”.
-Light transmittance Copolymer as a sample is coated on a silicon substrate with a film thickness (d) of 500 nm, and the complex refractive index (refractive index n and extinction coefficient k) of the copolymer is measured using a spectroscopic ellipsometer. , Measured at an exposure wavelength (λ) of 193 nm. From these measurement conditions and measurement results, the transmittance (I / I ₀ ) is calculated by the following equation. (However, when the transmittance is expressed in%, I / I ₀ is multiplied by 100.)
I / I ₀ = exp (−4πdk / λ)

Example 1
Under a nitrogen atmosphere, 20.0 parts of 1,4-dioxane was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, and the temperature of the hot water bath was raised to 80 ° C. while stirring. 17.8 parts of 1-isobornyl methacrylate (50 mol% with respect to all components of the monomer), 24.8 parts of β-methacryloyloxy-β-methyl-δ-valerolactone (50 with respect to all components of the monomer) Mol%), 62.5 parts of 1,4-dioxane, and 1.9 parts of azobisisobutyronitrile were dropped into the flask over 6 hours at a constant rate, and then 80 ° C. Was maintained for 2 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran and dropped into about 10-fold amount of methanol with stirring to obtain a white precipitate (copolymer A). The obtained precipitate was separated by filtration, dried at 60 ° C. under reduced pressure for about 40 hours, and the physical properties of copolymer A were measured.

(Examples 2 to 8)
Copolymers B to H were obtained in the same manner as in Example 1 except that the total number of moles of the monomers was not changed and the monomers and the amounts charged were changed as shown in Table 1. Table 1 shows the results of measuring the physical properties of the obtained copolymers B to H.

Example 9
In a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, in a nitrogen atmosphere, 22.8 parts of 1-isobornyl methacrylate (41 mol% with respect to all components of the monomer), β-methacryloyloxy-β -Methyl-δ-valerolactone 20.3 parts (41 mol% with respect to all monomers), methyl methacrylate 4.5 (18 mol% with respect to all monomers), 1,4-dioxane 82.5 parts and 3.8 parts of azobisisobutyronitrile were all added, the temperature of the hot water bath was raised to 80 ° C. with stirring, and polymerization was carried out at that temperature for 8 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran and added dropwise to about 10-fold amount of methanol with stirring to obtain a white precipitate (copolymer I). The obtained precipitate was separated by filtration, dried at 60 ° C. under reduced pressure for about 40 hours, and the physical properties of copolymer I were measured. The results are shown in Table 2.

(Examples 10 to 14)
Copolymers J to N were obtained in the same manner as in Example 9, except that the total number of moles of the monomers was not changed and the monomers and the charging ratio thereof were changed as shown in Table 2. Table 2 shows a result obtained by measuring physical properties of the obtained copolymers J to N.

(Comparative Example 1)
In a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, 27.8 parts of 1-isobornyl methacrylate, 24.8 parts of β-methacryloyloxy-β-methyl-δ-valerolactone, under a nitrogen atmosphere, , 4-dioxane 82.5 parts and azobisisobutyronitrile 3.8 parts were all added, the temperature of the hot water bath was raised to 80 ° C. with stirring, and polymerization was carried out at that temperature for 8 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran and dropped into about 10-fold amount of methanol while stirring to obtain a white precipitate (copolymer O). The obtained precipitate was separated by filtration, dried at 60 ° C. under reduced pressure for about 40 hours, and the physical properties of the copolymer O were measured.

(Comparative Examples 2-6)
Copolymers P to T were obtained in the same manner as in Comparative Example 1 except that the total number of moles of the monomers was not changed and the monomers and the amounts charged were changed as shown in Table 3. Table 3 shows the results of measurement of physical properties of the obtained copolymers P to T.

The resist composition for semiconductor production of the present invention has high uniformity and is excellent in sensitivity and resolution. The copolymer of the present invention is excellent as an ArF resist resin because it has excellent transparency to an ArF excimer laser (wavelength: 193 nm).

Claims (3)

A copolymer obtained by polymerizing a monomer having an alicyclic skeleton, a monomer having a lactone skeleton, and another vinyl monomer,
A copolymer in which the other vinyl monomer has a higher polarity than the monomer having the alicyclic skeleton and a lower polarity than the monomer having the lactone skeleton. . A copolymer obtained by polymerizing a monomer having an alicyclic skeleton, a (meth) acrylate having a substituted or unsubstituted γ-butyrolactone ring, and another vinyl monomer . A resist composition comprising the copolymer according to claim 1.