JP2003327628A - Copolymer of vinyl ether with alicyclic structure and base polymer for resist containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a base polymer for a resist capable of improving resistance to dryetching without deteriorating transparency and resolution, or the like, as advantages of acrylic resist materials, and suitably useful as the base polymer for the resist using an exposing light source with a short wave length light such as an ArF eximer laser. <P>SOLUTION: The subject copolymer has (a) a monomer unit selected from acrylic acid derivatives and methacrylic acid derivatives and (b) a repeating unit of formula (1) (wherein, R<SP>1</SP>, R<SP>2</SP>and R<SP>3</SP>are each hydrogen atom, hydroxy, an alkoxy, a halogen atom or a 1-6C alkyl, A is a single bond, a 1-4C alkylene, or a bivalent group formed by combining the alkylene group with an oxygen containing group selected from an ether bond, an ester bond and carbonyl group, and B is a 5-30C alicyclic hydrocarbon group), and the base polymer for the resist contains the copolymer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel copolymer and a base polymer for photoresist using the same, and particularly when using a short wavelength light such as ArF excimer laser light (193 nm) as an exposure energy source. It relates to a suitable base polymer for photoresist.

[0002]

2. Description of the Related Art In recent years, with the demand for higher density and higher integration of semiconductor elements, the wavelength of exposure energy source used in photolithography process has been shortened. That is, from the conventionally used g-line (436 nm) and i-line (365 nm), KrF excimer laser light (248 nm) is becoming mainstream now, and in the future, to shorter wavelength ArF excimer laser light (193 nm). Is being considered for migration.

As a base polymer of a resist material used in photolithography, a novolak resin is mainly used when a g-ray or an i-ray is used as a light source, and a hydroxystyrene-based resin is mainly used when a KrF excimer laser is used as a light source. Resins have been prized. These phenolic resins are
This is because it is excellent in various properties required as a resist material such as alkali solubility after exposure, dry etching resistance and substrate adhesion. However, since all of these phenolic resins show extremely strong light absorption derived from an aromatic ring near 193 nm, they cannot be used as a resist material when an ArF excimer laser is used as a light source.

On the other hand, when a resin having no aromatic ring is used as a resist material as a resin having no absorption in the wavelength range, there arises a problem that sufficient dry etching resistance cannot be obtained. It is generally known that increasing the carbon density of the resin is important for improving dry etching resistance, and as a means to solve this problem, a method of introducing an alicyclic skeleton into the main chain or side chain is proposed. Has been done.

As an example of introducing an alicyclic skeleton into the main chain, a method of polymerizing a norbornene derivative in the presence of a metal catalyst to obtain a polynorbornene type resin (J. Photopolym. Sci. Techn
ol., 11, 475 (1998)) and radical polymerization of norbornene derivative and maleic anhydride to obtain an alternating copolymer resin (Proc.SPIE, 2724,355 (1996), J. Photopolym. Sci. Te.
chnol., 12, 553 (1999), U.S. Pat. No. 5,843,624.
No.) are known. Furthermore, a method of obtaining an alternating copolymer resin by radical polymerization of vinyl ether and maleic anhydride is also known. Examples of the resist material obtained by such a method include those disclosed in JP 2001-200016 A, Proc. SPIE, 3999, 54 (2000) and the like.

As an example of introducing an alicyclic skeleton into the side chain, there is a method of introducing an alicyclic group such as adamantane skeleton, tetracyclododecane skeleton or terpenes into the ester side chain of acrylic acid or methacrylic acid resin. Are known. Examples of the resist material obtained by such a method include those disclosed in JP-A-4-39665, JP-A-7-199467, and JP-A-8-82925.

However, when a polynorbornene type resin is obtained with a metal catalyst, there are problems such as difficulty of polymerization and removal of the metal used for the catalyst, and in the case of an alternating copolymer resin using maleic anhydride, However, there remain problems with low transparency at the exposure wavelength and storage stability. on the other hand,
Acrylic resins with alicyclic groups introduced into their side chains are excellent in terms of transparency and resolution, but their dry etching resistance cannot be said to be sufficient and they are difficult to use due to the tendency toward thinner resist films. Is expected to become.

As described above, in the field of photolithography where wavelengths are becoming shorter, it is essential to develop a corresponding resist material, and a base polymer satisfying at the same time physical properties such as transparency, dry etching resistance and substrate adhesion. The current situation is that trial and error is being made toward the search for.

[0009]

The object of the present invention is to provide Ar
Polymers that can be suitably used as a base polymer for a resist, such as F excimer laser, which uses short-wavelength light as a light source, that is, polymers that can satisfy performances such as transparency at the exposure wavelength, dry etching resistance, and substrate adhesion. To provide.

[0010]

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, by incorporating a specific repeating unit in the copolymer, the advantages of the conventional acrylic resist material are obtained. The inventors have found that it is possible to improve dry etching resistance without impairing transparency, resolution, etc., and have completed the present invention.

That is, the present invention provides a copolymer having (a) a monomer unit selected from acrylic acid derivatives and methacrylic acid derivatives, and (b) a repeating unit represented by the following general formula (1), and The present invention provides a base polymer for resist, which comprises:

[0012]

[Chemical 2]

(In the formula, R ¹ , R ² and R ³ are each independently a hydrogen atom, a hydroxyl group, an alkoxy group, a halogen atom or an optionally substituted alkyl group having 1 to 6 carbon atoms. Indicates: A is a single bond, an alkylene group having 1 to 4 carbon atoms which may have a substituent, or a divalent group obtained by combining the alkylene group with an oxygen-containing group selected from an ether bond, an ester bond and a carbonyl group. B represents an alicyclic hydrocarbon group having 5 to 30 carbon atoms which may have a substituent, and a part of R ² or R ^{3 and} a part of A or B are bonded to each other. And may form a ring.).

The present invention also provides a resist composition containing the above-mentioned resist base polymer and a photo-acid generator capable of generating an acid upon exposure.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The copolymer of the present invention is a copolymer having a monomer unit (a) and a repeating unit (b) represented by the general formula (1).

Examples of the acrylic acid derivative or methacrylic acid derivative as the monomer unit (a) include acrylic acid, methacrylic acid, acrylates, methacrylates, acrylamides, and methacrylamides, among which acrylates and methacrylates. Is preferred. As the acrylates and methacrylates, as an ester residue, a linear, branched or cyclic alkyl group having 1 to 24 carbon atoms, a trialkylsilyl group, a group having a cyclic ketone structure, a group having a cyclic ether structure, Examples thereof include a group having a lactone ring structure. Here, the cyclic alkyl group also includes a polycyclic group. Further, these ester residues may be substituted with a halogen atom, a hydroxy group or the like. More specifically, methyl acrylate, methyl methacrylate, methyl α-trifluoromethyl acrylate, trimethylsilyl methacrylate, tert
-Butyl methacrylate, 3-oxocyclohexyl methacrylate, tetrahydropyranyl methacrylate,
Tetrahydrofuranyl methacrylate, menthyl methacrylate, norbornyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-
Examples thereof include 2-adamantyl methacrylate, 3-hydroxyadamantyl methacrylate, tricyclodecanyl methacrylate, tetracyclododecanyl methacrylate, acrylate having a lactone ring structure, and methacrylate having a lactone ring structure. Specific examples of the lactone ring structure include a γ-butyrolactone ring structure, a δ-valerolactone ring structure and the following structures.

[0017]

[Chemical 3]

Among these acrylates or methacrylates, when they are used as a base polymer for resist, they have a structure in which a protecting group is eliminated by an acid to form an alkali-soluble group such as a carboxyl group. As a result, A compound in which the copolymer is soluble in an alkaline aqueous solution is preferable, and specifically, trimethylsilyl methacrylate, tert-butyl methacrylate, 3-oxocyclohexyl methacrylate, tetrahydropyranyl methacrylate, tetrahydrofuranyl methacrylate, 2
Acrylates or methacrylates having a residue susceptible to acid decomposition such as -methyl-2-adamantyl methacrylate and 2-ethyl-2-adamantyl methacrylate are preferable.

Norbornyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2
-Acrylates or methacrylates containing a polycyclic alicyclic saturated hydrocarbon structure such as ethyl-2-adamantyl methacrylate, tricyclodecanyl methacrylate, and tetracyclododecanyl methacrylate are copolymers having excellent dry etching resistance. Is preferable because
Acrylates or methacrylates having a lactone ring structure are preferable because the hydrophobicity of the alicyclic hydrocarbon structure is alleviated by the effect of the lactone ring structure and the developability and substrate adhesion are excellent.

In the general formula (1) showing the repeating unit (b) used in the present invention, the alkoxy group among the groups represented by R ^{1 to} R ³ is an alkoxy group having 1 to 4 carbon atoms, for example, methoxy. Group, ethoxy group, propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, te
An rt-butoxy group etc. can be mentioned. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The alkyl group having 1 to 6 carbon atoms may be linear, branched or cyclic, and examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and sec-butyl. Group, tert-butyl group, cyclopentyl group, cyclohexyl group and the like. Examples of the substituent of the alkyl group include a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a halogen atom and the like. In the present invention, among these R ¹ , R ² and R ³ , a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms is preferable, independently of each other.

In the general formula (1), A is a single bond, an alkylene group having 1 to 4 carbon atoms which may have a substituent, or an alkylene group and an ether bond (-O-), an ester bond (-). A divalent group in which an oxygen-containing group selected from COO-) and a carbonyl group (-CO-) is combined is shown. here,
Examples of the alkylene group having 1 to 4 carbon atoms include methylene group, ethylene group, propylene group, trimethylene group and tetramethylene group. Examples of the substituent of the alkylene group include a halogen atom, an alkyl group, a haloalkyl group, a hydroxyl group, an alkoxy group and the like. In addition, as a group in which the alkylene group and the oxygen-containing group are combined, —CH _{2
CH 2 O -, - CH 2} CH 2 COO -, - CH (CH 3) C
H ₂ COO-, and the like.

Of these, a single bond or an alkylene group having 1 to 4 carbon atoms is preferable in the present invention.

The alicyclic hydrocarbon group represented by B may be monocyclic or polycyclic, and specific examples thereof include groups having a monocyclo, bicyclo, tricyclo or tetracyclo structure having 5 to 30 carbon atoms. You can These alicyclic hydrocarbon groups may have a substituent.

Examples of the monocyclic alicyclic structure include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and a cyclodecanyl group. Examples of the polycyclic alicyclic structure include a decalin residue, a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group and an adamantyl group. Among them, a compound having a polycyclic structure such as a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group, and an adamantyl group can increase the carbon density and thus the dry etching resistance of the base polymer for resist. It is highly effective and preferable.

Examples of the substituent of these alicyclic hydrocarbon groups include a hydroxyl group, an alkoxy group, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group, an alkenyl group, Examples thereof include an acyl group. Here, examples of the alkoxy group include alkoxy groups having 1 to 4 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group. it can. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Examples thereof include isobutyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group and the like. The alkoxycarbonyl group has a total carbon number of 2 to 5
A linear or branched alkoxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, sec-butoxycarbonyl group, t
ert-butoxycarbonyl group, etc .; Cyclic alkyloxycarbonyl group containing a hetero atom, for example, 3-oxocyclohexyloxycarbonyl group, tetrahydropyranyloxycarbonyl group, tetrahydrofuranyloxycarbonyl group, etc .; A formula alkyloxycarbonyl group, for example, a 2-methyl-2-adamantyloxycarbonyl group, a 2-ethyl-2-adamantyloxycarbonyl group and the like can be mentioned. Examples of the alkenyl group include alkenyl groups having 2 to 6 carbon atoms, such as vinyl group, 1-propenyl group, allyl group, butenyl group, pentenyl group and hexenyl group. Examples of the acyl group include alkanoyl groups having 2 to 5 carbon atoms, such as acetyl group, propionyl group and butyryl group.

Further, these substituents may form a ring structure with carbon of the alicyclic hydrocarbon skeleton, and specifically, form a cyclic ether, a cyclic ketone, a lactone ring structure or the like. Good.

The substituent of the substituted alkyl group contains a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a carboxyl group, a linear or branched alkoxycarbonyl group having 2 to 5 carbon atoms, and a hetero atom. Examples thereof include a cyclic alkyloxycarbonyl group and an alicyclic alkyloxycarbonyl group having 5 to 15 carbon atoms.

Among the substituents (including the substituents of the substituted alkyl group) contained in the alicyclic hydrocarbon group, polar groups such as a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, an acyl group and a lactone structure are alicyclic. It is preferable because the hydrophobicity of the formula hydrocarbon structure can be relaxed, and the developability and substrate adhesion can be improved.

Specific examples of the alicyclic hydrocarbon group having a polar group include hydroxynorbornyl group, hydroxytricyclodecanyl group, hydroxymethyltricyclodecanyl group, hydroxytetracyclododecanyl group, Examples thereof include a hydroxymethyltetracyclododecanyl group, a hydroxyadamantyl group, a dihydroxyadamantyl group, a trihydroxyadamantyl group, a carboxynorbornyl group, a methoxycarbonylnorbornyl group and an ethoxycarbonylnorbornyl group.

Further, specific examples of the alicyclic hydrocarbon group having a lactone structure include those having the following structure as a basic skeleton.

[0031]

[Chemical 4]

Of the substituents contained in the alicyclic hydrocarbon group (including the substituents of the substituted alkyl group), a substituent having a structure in which the protecting group is eliminated by an acid to form an alkali-soluble group, For example, tert-butoxycarbonyl group, 3
An acid-decomposable alkoxycarbonyl group such as -oxocyclohexyloxycarbonyl group, tetrahydropyranyloxycarbonyl group, tetrahydrofuranyloxycarbonyl group, 2-methyl-2-adamantyloxycarbonyl group, 2-ethyl-2-adamantyloxycarbonyl group preferable.

Typical examples of the polymerizable compound which gives the structural unit (b) include vinyl ether derivatives. The method for producing the vinyl ether derivative providing the structural unit (b) is not particularly limited, but typical production methods include potassium hydroxide, potassium alcoholate, and alicyclic hydrocarbon compound having a hydroxyl group.
A known method of adding acetylene using sodium hydroxide, sodium alcoholate or the like as a catalyst can be mentioned. In the acetylene addition reaction, the reaction pressure is generally normal pressure to 10 MPa, preferably normal pressure to 5 MPa, and the reaction temperature is generally 20 to 250 ° C, preferably 60 to 200 ° C.
The reaction time is generally 1 to 12 hours, preferably 2 to 6 hours, but is not limited thereto. After the reaction
The desired vinyl ether derivative can be obtained by purification by a method such as distillation.

The copolymer of the present invention can be made into a multi-component copolymer by further copolymerizing another polymerizable compound (c). Other compounds that can be copolymerized include:
For example, linear or branched alkyl vinyl ether,
Or a linear or branched alkyl vinyl ether derivative monomer in which a part of the alkyl group is substituted with an alkoxy group, a hydroxyl group, a hydroxyalkyl group, a carboxyl group, an alkoxycarbonyl group or the like; norbornene or a part thereof is an alkyl group, an alkoxy group or a hydroxyl group. , Norbornene derivative monomers substituted with a hydroxyalkyl group, a carboxyl group, an alkoxycarbonyl group, and maleic anhydride.

The total content of the monomer unit (a) in the copolymer of the present invention is preferably 50 mol% to 95 mol%, and particularly preferably 70 mol% to 90 mol%. The content of the repeating unit represented by the general formula (1) in (b) is preferably 5 mol% to 50 mol%, and particularly preferably 10 mol% to 30 mol%. If the content of (b) is less than 5 mol%, the effect of improving dry etching resistance may not be sufficient, and
If it exceeds 0 mol%, the polymerization yield may deteriorate. The content of the other polymerizable compound is preferably 0 mol% to 50 mol%.

The method for producing the copolymer of the present invention is not particularly limited, but as a typical production method, an acrylic acid derivative or a methacrylic acid derivative giving the monomer unit (a),
It can be produced by copolymerizing the vinyl ether derivative of (b) and another polymerizable compound of (c) by a conventional method. Each of the acrylic acid derivative or methacrylic acid derivative which gives the monomer unit (a) and the vinyl ether derivative (b) may use one type of polymerizable compound, or may use two or more types of compounds in combination. It is good, but it is preferable that any one or more of the polymerizable compounds used contains a structural unit capable of generating an alkali-soluble group when the protecting group is eliminated by an acid. Further, (c) may be added as necessary.

As a method of copolymerization, for example, in the case of producing by radical copolymerization, the objective (a), (b)
It can be carried out by dissolving the monomers (c) and (c) in a solvent-free or suitable solvent, and preferably adding a radical polymerization initiator and stirring under an atmosphere of an inert gas such as nitrogen.

When a solvent is used, for example, benzene,
Aromatic hydrocarbons such as toluene and xylene; hexane,
Saturated hydrocarbons such as cyclohexane; ethers such as diethyl ether, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether; acetone, 2
-Ketones such as butanone; halogenated hydrocarbons such as methylene chloride and chloroform; esters such as methyl acetate and ethyl acetate; polar organic solvents containing heteroatoms such as N, N-dimethylformamide and dimethyl sulfoxide;
Various solvents can be used and may be appropriately selected depending on the solubility of the monomer.

As the radical polymerization initiator, for example,
Azobis-type polymerization initiators such as α, α′-azobisisobutyronitrile and 2,2′-azobis (methyl 2-methylpropionate); use of peroxide-type polymerization initiators such as benzoyl peroxide You can

The reaction temperature is usually in the range of 30 to 150 ° C, preferably in the range of 50 to 100 ° C, and the reaction time is usually in the range of 1 to 24 hours.

The molecular weight of the copolymer of the present invention is not particularly limited, but when it is used as a base polymer for resist, if the molecular weight is too low, the strength becomes insufficient and the formation of a resist film becomes difficult. If it is too high, it will be difficult to obtain a uniform coating film by the usual spin coating method.
Usually, the weight average molecular weight is preferably in the range of 1,000 to 300,000, more preferably in the range of 3,000 to 100,000. The molecular weight of the copolymer can be adjusted to a desired value by manipulating reaction factors such as reaction temperature, monomer concentration, polymerization initiator concentration, and addition of chain transfer agent.

Since the copolymer of the present invention has excellent dry etching resistance, it is useful as a base polymer for resists. A suitable resist composition can be obtained by adding a photo-acid generator that generates an acid upon exposure to the base polymer for a resist.

The kind of the photo-acid generator is not particularly limited, and examples thereof include diphenyliodonium trifluoromethanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-tert-butylphenyl) iodonium hexafluoroantimonate. Nate, bis (4-tert-butylphenyl) iodonium tetrafluoroborate, bis (4-
Tert-butylphenyl) iodonium hexafluorophosphate, cyclohexyl (methyl) (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, dicyclohexyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate,
Onium salts such as triphenylsulfonium camphorsulfonate; 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- [2 −
Halogenated organic compounds such as (furan-2-yl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine; Sulfonic acid compounds such as pyrogallol tris trifluoromethanesulfonate; N-hydroxysuccinimide trifluoromethanesulfonate Known compounds such as organic acid imide compounds such as 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate; bissulfonyldiazomethane compounds; quinonediazide compounds and the like can be mentioned. The blending amount of these photo-acid generators is not particularly limited, but is usually 0.1 to 30 per 100 parts by weight of the copolymer.
Parts by weight, more preferably 1 to 10 parts by weight.

The resist composition of the present invention is usually used by dissolving it in a solvent. The type of solvent is not particularly limited, and a generally known solvent for resist may be used. For example, ketones such as acetone, 2-butanone, methylamyl ketone, cyclopentanone, cyclohexanone; alcohols such as n-propanol, isopropanol, n-butanol, isobutanol, cyclohexanol; ethylene glycol, propylene glycol, diethylene glycol, etc. Glycols; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, and other glycol ethers; dioxane, tetrahydrofuran, and other cyclic ethers; methyl acetate, ethyl acetate, Propyl acetate, methyl propionate, ethyl propionate,
Examples thereof include esters such as methyl lactate and ethyl lactate.

In the resist composition of the present invention, if necessary, a surfactant, an antioxidant, a sensitizer, a heat stabilizer,
Additives such as amines can also be used in combination.

The base polymer for a resist using the copolymer of the present invention can improve the dry etching resistance without deteriorating the advantages of the acrylic resist material such as transparency and resolution.

As one of the methods for evaluating the dry etching resistance, an empirical formula [Ohnishi parameter = N / (Nc-
No): Here, N, Nc, and No represent the total number of atoms, the number of carbon atoms, and the number of oxygen atoms in the monomer, respectively. The smaller these values are, the higher the dry etching resistance is.]
(J. Electrochem. Soc., 130 (1), 143-6, (1983)) is known. In the same method, for example, in the structural unit of the general formula (1), R ^{1 to} R ³ are hydrogen atoms, A is a single bond, and B is an adamantyl group. It is calculated as 0.82. On the other hand, as in the prior art, the parameter of an acrylic acid ester (adamantyl acrylate) also having an adamantyl group is calculated to be 3.00, so that the copolymer of the present invention has excellent dry etching resistance. Is clear.

[0048]

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

Reference Example 1 Preparation of tricyclodecane dimethanol monovinyl ether (hereinafter referred to as TCDMV) 300 g of tricyclodecane dimethanol (1.53 mo)
26 g (0.46 mol) of potassium hydroxide was added to 1) and the mixture was heated and stirred under reduced pressure to distill off water in the system. 450 g of 1,3-dimethyl-2-imidazolidinone was added thereto to form a uniform solution, acetylene gas was supplied to increase the internal pressure to 0.04 MPa (gauge pressure), and the reaction was performed at 105 ° C. for 4 hours. It was After the completion of the reaction, the product was purified by vacuum distillation, and 100 g (0.45 mo
l) was obtained.

Example 1 Production of copolymer (I) represented by the following formula (I)

[0051]

[Chemical 5]

Tert-butyl methacrylate (hereinafter,
It is referred to as TBMA. ) 1.42 g (10 mmol) and T
2.22 g (10 mmol) of CDMV was added to 3.31 g of 2
-Dissolved in butanone, 0.046 g of α, α'-azobisisobutyronitrile (hereinafter referred to as AIBN) was added as a polymerization initiator, and the mixture was stirred at 80 ° C for 3 hours under a nitrogen atmosphere. Then, this reaction solution was added dropwise to a large amount of a mixed solution of methanol and water with stirring to obtain 1.63 g of the desired copolymer as a white precipitate. The GPC weight average molecular weight of the obtained copolymer was 26,000. The content ratio of each structural unit in the obtained copolymer was x = 88 and y = 12 in the formula (I). ¹³ C-of copolymer (I)
The NMR spectrum is shown in FIG. In the figure, the peak derived from the carbon atom of the ester carbonyl group is 177p.
A peak derived from a carbon atom adjacent to a hydroxyl group was observed near 67 ppm near pm.

Example 2 Production of copolymer (II) represented by the following formula (II)

[0054]

[Chemical 6]

2-Methyl-2-adamantyl methacrylate (hereinafter referred to as MAMA) 1.17 g (5 mmol) and TCDMV 2.22 g (10 mmol) were added to 7.
It is dissolved in 0 g of 2-butanone and used as a polymerization initiator
0.12 g of 2'-azobis (methyl 2-methylpropionate) (hereinafter referred to as MAIB) was added, and the mixture was stirred at 80 ° C for 5 hours under a nitrogen atmosphere. Then, this reaction liquid was dropped into a large amount of methanol while stirring to obtain 1.16 g of a target copolymer as a white precipitate. The GPC weight average molecular weight of the obtained copolymer was 5,700. Also,
The content ratio of each structural unit in the obtained copolymer was x = 74 and y = 26 in the formula (II). The ¹³ C-NMR spectrum of the copolymer (II) is shown in FIG. In the figure, the peak derived from the carbon atom of the ester carbonyl group was observed near 176 ppm, and the peak derived from the methylene carbon atom adjacent to the hydroxyl group was observed around 67 ppm.

Example 3 Production of copolymer (III) represented by the following formula (III)

[0057]

[Chemical 7]

MAMA 2.34 (10 mmol), norbornane lactone methacrylate (hereinafter referred to as NLM) 2.22 g (10 mmol) and TCDMV4.3.
44 g (20 mmol) was dissolved in 18.0 g of 2-butanone, 0.26 g of AIBN was added as a polymerization initiator, and the mixture was stirred at 80 ° C. for 4 hours under a nitrogen atmosphere. Then, the reaction solution was dropped into a large amount of methanol while stirring,
4.30 g of the desired copolymer was obtained as a white precipitate. The GPC weight average molecular weight of the obtained copolymer was 10,900. In addition, the content ratio of each structural unit in the obtained copolymer is x = 40, y = 43, z = in the formula (III).
It was 17. The ¹³ C-NMR spectrum of the copolymer (III) is shown in FIG. In the figure, peaks derived from carbonyl carbon atoms of lactone and ester are 175-1
At around 80 ppm, a peak derived from a carbon atom adjacent to the oxygen atom of the hydroxyl group was observed at around 67 ppm.

[0059]

INDUSTRIAL APPLICABILITY The copolymer of the present invention can improve dry etching resistance without deteriorating the advantages of the acrylic resist material such as transparency and resolution. It can be suitably used as a base polymer for a resist having a short wavelength as an exposure light source.

[Brief description of drawings]

FIG. 1 is ¹³ C—N of the copolymer (I) obtained in Example 1.
It is an MR spectrum.

FIG. 2 is ¹³ C—N of the copolymer (II) obtained in Example 2.
It is an MR spectrum.

FIG. 3 shows ¹³ C-of the copolymer (III) obtained in Example 3.
It is an NMR spectrum.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiji Takahashi             2-3-18 Inage Higashi, Inage-ku, Chiba-shi, Chiba Prefecture             606 (72) Inventor Takuya Miwa             2445 Goi, Ichihara-shi, Chiba C-103 F term (reference) 2H025 AA01 AA09 AA14 AB16 AC08                       AD03 BE00 BE10 BG00 CB06                       CB14 CB41 FA10 FA17                 4J100 AE09Q AG08Q AJ02P AL03P                       AL08P AM14P BA03P BA03Q                       BA04Q BA11P BA11Q BA72P                       BB00Q BB18P BC04P BC07P                       BC07Q BC08P BC08Q BC09P                       BC09Q BC53P BC53Q JA38

Claims (8)

[Claims] 1. A copolymer having (a) a monomer unit selected from an acrylic acid derivative and a methacrylic acid derivative, and (b) a repeating unit represented by the following general formula (1). [Chemical 1] (In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom, a hydroxyl group, an alkoxy group, a halogen atom or an optionally substituted alkyl group having 1 to 6 carbon atoms; A
Is a single bond, an alkylene group having 1 to 4 carbon atoms which may have a substituent, or a divalent group obtained by combining the alkylene group with an oxygen-containing group selected from an ether bond, an ester bond and a carbonyl group. Shown: B represents an alicyclic hydrocarbon group having 5 to 30 carbon atoms which may have a substituent. R ²
Alternatively, a part of R ^{3 and} a part of A or B may be bonded to each other to form a ring. ). 2. The alicyclic hydrocarbon group which may have a substituent represented by B in the general formula (1) is a substituted or unsubstituted norbornyl group, tricyclodecanyl group or tetracyclododecanyl group. The copolymer according to claim 1, which is a group or an adamantyl group. 3. The alicyclic hydrocarbon group which may have a substituent represented by B in the general formula (1) is an alicyclic hydrocarbon group having a polar group as a substituent. Or the copolymer described in 2. 4. The copolymer according to claim 1, wherein the alicyclic hydrocarbon group represented by B in the general formula (1) is an alicyclic hydrocarbon group having a lactone structure. 5. An alicyclic hydrocarbon group which may have a substituent represented by B of the general formula (1) replaces a structure in which a protecting group is eliminated by an acid to form an alkali-soluble group. The copolymer according to claim 1 or 2, which is an alicyclic hydrocarbon group having a group. 6. The acrylic acid derivative or the methacrylic acid derivative is an acrylate or a methacrylate having a structure in which a protecting group is eliminated by an acid to generate an alkali-soluble group. Copolymer of. 7. A base polymer for a resist, containing the copolymer according to claim 1. 8. A resist composition comprising the resist base polymer according to claim 7 and a photoacid generator capable of generating an acid upon exposure.