JP4851140B2 - (Meth) acrylic acid ester, polymer, resist composition, and method for producing substrate on which pattern is formed - Google Patents

Description

  The present invention relates to a polyfunctional (meth) acrylic acid ester having an acetal structure useful for the production of resins used in paints, adhesives, pressure-sensitive adhesives, ink resins, resist compositions, molding materials, optical materials, and the like. The present invention relates to a polymer contained as a structural unit. The present invention also relates to a chemically amplified resist composition suitable for fine processing using an excimer laser, an electron beam, and an X-ray, and a method for producing a substrate on which a pattern is formed.

In recent years, miniaturization has rapidly progressed in the field of microfabrication in the manufacture of semiconductor elements and liquid crystal elements due to advances in lithography technology. As a method for miniaturization, generally, a shorter wavelength of irradiation light is used. Specifically, from conventional ultraviolet rays typified by g-line (wavelength: 438 nm) and i-line (wavelength: 365 nm) to DUV ( The irradiation light is changing to Deep Ultra Violet).
At present, KrF excimer laser (wavelength: 248 nm) lithography technology is introduced into the market, and ArF excimer laser (wavelength: 193 nm) lithography technology for further shortening the wavelength is about to be introduced. Further, as a next-generation technique, an F ₂ excimer laser (wavelength: 157 nm) lithography technique has been studied. In addition, as a slightly different type of lithography technology, an electron beam lithography technology and an EUV lithography technology using extreme ultraviolet light (Extreme Ultra Light Light: EUV light) in the vicinity of 13.5 nm wavelength are also energetically studied. .
As a high-resolution resist for such short-wavelength irradiation light or electron beam, a “chemically amplified resist” containing a photoacid generator has been proposed. At present, improvements and development of this chemically amplified resist are energetically active. It is being advanced.

As a resist resin used in ArF excimer laser lithography, an acrylic resin that is transparent with respect to light having a wavelength of 193 nm has attracted attention. As such an acrylic resin, for example, a chemically amplified resist composition containing a polymer whose side chain is decomposed to show alkali solubility is disclosed (see Patent Document 1).
However, when the polymer described in Patent Document 1 is used for a resist composition for ArF excimer laser lithography, there is a problem in solubility in a developing solution, and thus there is a problem that defects occur. . There is also a problem that the line edge roughness is large.

On the other hand, in KrF excimer laser lithography, a resist composition having high resolution and excellent etching resistance is disclosed (see Patent Document 2). In this document, a hydroxystyrene resin obtained by copolymerizing a crosslinking agent having a tertiary ester structure that decomposes with an acid is used as a raw material.
However, since the resin described in Patent Document 2 is a styrene resin, it cannot be used for ArF excimer laser lithography. Therefore, it is conceivable to use an acrylic resin obtained by copolymerizing a crosslinking agent having a tertiary ester structure described in Patent Document 2, but a crosslinking agent having a tertiary ester structure that decomposes with an acid is simply an acrylic resin. Even when copolymerized with a resin, the line edge roughness and defects cannot be sufficiently improved.
JP 2003-122007 A Japanese Patent Laid-Open No. 2002-62656

  An object of the present invention is to provide a resist composition in which the generation of defects is suppressed and the line edge roughness of the resist pattern can be reduced, and is a polymer suitable for such a resist composition. It is to provide a polymer having good thermal stability, and to provide a polyfunctional (meth) acrylic acid ester suitable for such a polymer.

  As a result of intensive studies in view of the above problems, the inventors of the present invention have excellent stability in polyfunctional (meth) acrylic acid esters having one acetal structure in one molecule in DUV excimer laser lithography or electron beam lithography. And, by using a polymer containing the polyfunctional (meth) acrylic acid ester as a structural unit for the resist composition, it was found that the generation of defects was suppressed and the line edge roughness was also reduced, leading to the present invention. .

That is, this invention relates to the resist material which consists of a polymer which contains the structural unit represented by following formula (2) in 0.5 mol%-30 mol% in the structural unit of a polymer; The polymer which contains the structural unit represented by following formula (2) in 0.5 mol%-30 mol% in the structural unit of a polymer, and also contains the structural unit which has an acid leaving group. It relates to a resist composition containing the polymer ; and relates to a method for producing a substrate on which a pattern is formed using the resist composition.

(In formula (2), R ₁ , R ₂ , R ₃ Each independently represents a hydrogen atom or a methyl group, and A represents an alkylene group which may have a substituent, a cycloalkylene group which may have a substituent, an oxyalkylene group which may have a substituent, Represents a polyoxyalkylene group which may have a substituent, or an arylene group which may have a substituent, and m and n are each independently 0 or 1, and —O—A— ( O) _m The structure of-has no acetal structure. )

  The polyfunctional (meth) acrylic acid ester of the present invention is excellent in thermal stability, and particularly when used as a resist polymer, when a resist composition containing the polymer is used, In comparison, the solubility in the developer is improved, the generation of defects is suppressed, and the line pattern roughness of the resulting resist pattern is small.

  The present invention will be described below. In the text, “(meth) acrylic acid” represents acrylic acid and / or methacrylic acid.

First, the polyfunctional (meth) acrylic acid ester having an acetal structure represented by the formula (1) will be described.

R _{1 to} R ₃ in the formula (1) represent a hydrogen atom or a methyl group. When R ₁ or R ₂ is a methyl group, the thermal stability and storage stability of the monomer tend to be superior to those when R ₁ or R ₂ is a hydrogen atom. When R ₃ is a methyl group, the acid decomposability tends to be improved compared to when R ₃ is a hydrogen atom. Therefore, when used in resist applications, the line edge roughness tends to be smaller and defects are not improved. It tends to decrease. On the other hand, when R ₃ is a hydrogen atom, the thermal stability and storage stability of the monomer tend to be superior to those when R ₃ is a methyl group.

A in Formula (1) has an alkylene group that may have a substituent, a cycloalkylene group that may have a substituent, an oxyalkylene group that may have a substituent, and a substituent. Represents a polyoxyalkylene group which may be substituted, or an arylene group which may have a substituent.
However, in formula (1), the structure of —O—A— (O) _m — does not have an acetal structure. When the structure of —O—A— (O) _m — in the formula (1) has an acetal structure, the structure represented by the formula (1) has two acetal structures. Since the tendency which is inferior to stability is seen, it is not preferable.
Here, the substituent represents a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, or a halogen.
A is an alkylene group which may have a substituent, a cycloalkylene group which may have a substituent, an oxyalkylene group which may have a substituent, a polyoxyalkylene group which may have a substituent, Or when it is an arylene group which may have a substituent, it exists in the tendency for thermal stability to improve and for storage stability to improve. Furthermore, there is a tendency that thermal decomposition during purification of the polyfunctional (meth) acrylic acid ester of the present invention, for example, distillation purification, does not easily occur.
Specific examples of A include the following.

Among these, (A-8), (A-9), (A-13), and (A-17) are preferable because the line edge roughness tends to be small. Moreover, (A-13) and (A-17) are particularly preferable from the viewpoint of easy availability of raw materials.
M and n in Formula (1) are each independently 0 or 1. From the viewpoint of reducing the molecular weight dispersion of the polymer of the present invention, n is preferably 1.
Specific examples of the polyfunctional (meth) acrylic acid ester having an acetal structure represented by the formula (1) of the present invention are illustrated below.

  Among these, since the line edge roughness tends to be small, (1-9) to (1-12), (1-17), (1-18), (1-19), and (1 -20) is preferred, and (1-17) and (1-18) are particularly preferred from the viewpoints of thermal stability and storage stability.

The polyfunctional (meth) acrylic acid ester having an acetal structure according to the present invention is a polyfunctional (meth) acrylic acid ester containing one acetal structure in one molecule as shown in the formula (1). . When the polymer containing the polyfunctional (meth) acrylic acid ester as a constituent unit is used for a resist composition for ArF excimer laser lithography, for example, it contains an acetal structure. By decomposing by acid, the molecular weight of the resin is lowered, so that the solubility in the developer is improved, the defect can be reduced, and the line edge roughness can be reduced.
Moreover, the polyfunctional (meth) acrylic acid ester of the present invention is characterized by containing one acetal structure in one molecule. By containing one acetal structure in one molecule, stability such as storage stability and thermal stability is remarkably improved as compared with the case where two or more acetal structures are contained in one molecule. As a result, it is possible to prevent thermal decomposition during purification of the polyfunctional (meth) acrylic acid ester of the present invention, for example, distillation purification.

As described above, the acetal structure represented by the formula (1) is decomposed by the action of acid or heat. For example, a polyfunctional methacrylate having the acetal structure represented by the following formula (1-17) is used. For example, a decomposition example of the acetal structure is shown.

As decomposition examples of the polyfunctional methacrylate represented by the formula (1-17), decomposition example 1, decomposition example 2, decomposition example 3, and decomposition example 4 are shown below.
Disassembly example 1:

Disassembly example 2:

Decomposition example 3:

Disassembly example 4:

Next, the manufacturing method of the polyfunctional (meth) acrylic acid ester which has an acetal structure represented by Formula (1) of this invention is demonstrated.
For example, a polyfunctional (meth) acrylic acid ester having an acetal structure represented by the formula (1-17) will be described as an example. The polyfunctional (meth) acrylic acid ester having an acetal structure represented by the formula (1-17) is a carboxyl group of methacrylic acid on the vinyl group of (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl (X). It can be produced by adding an acid.

This reaction (Scheme 1) may be performed using a solvent or may be performed without using a solvent.
The amount of methacrylic acid to be used is not particularly limited, but it is preferably 0.5 to 10 times by mole to (X), and 1.0 to 1 to 1 times from the viewpoint of removing methacrylic acid after the reaction. It is effective to use in the range of 8 times mole.
The reaction temperature is not particularly limited, but it is preferably performed in the range of 0 ° C to 180 ° C. When reacted at 0 ° C. or higher, the reaction rate tends to increase, and when reacted at 180 ° C. or lower, the decomposition reaction does not proceed and the yield tends to increase. The lower limit of the reaction temperature is more preferably 50 ° C. or higher, and the upper limit of the reaction temperature is more preferably 110 ° C. or lower.
Moreover, since this reaction is an exothermic reaction, it is preferable to react by dropping (meth) acrylic acid with respect to (X) in order to prevent the temperature from rising. The dropping speed is not particularly limited, but is preferably in the range of 10 to 1000 ml / min. The reaction time is not particularly limited, but is preferably 1 to 6 hours after the completion of dropping. Moreover, reaction time can also be shortened by making it react in presence of a Lewis acid.

After the reaction, distillation purification is performed. The distillation purification is preferably performed after removing excess (meth) acrylic acid. Although the removal method of (meth) acrylic acid is not particularly limited, it may be removed under reduced pressure, or an aqueous potassium carbonate solution, an aqueous potassium hydrogen carbonate solution, an aqueous sodium carbonate solution, an aqueous sodium hydrogen carbonate solution, an aqueous sodium hydroxide solution, or potassium hydroxide. You may wash | clean with alkaline solutions, such as aqueous solution. When distillation is performed without removing (meth) acrylic acid, the product is decomposed to produce (meth) acrylic acid, which tends to be mixed into the purified product.
The distillation method is not particularly limited, but thin film distillation is preferred from the viewpoint of decomposition during distillation.

Next, the polymer of the present invention will be described.
The polymer of this invention contains the structural unit represented by following formula (2). This polymer can be obtained by polymerizing a monomer containing a polyfunctional (meth) acrylic acid ester represented by the above formula (1).

In formula (2), R ₁ , R ₂ , R ₃ , A, m, and n are as defined in formula (1), and an acetal structure in the structure of —O—A— (O) _m — Does not have.

When R ₃ is a methyl group, the acid decomposability tends to be improved compared to when R ₃ is a hydrogen atom. Therefore, when used in resist applications, the line edge roughness tends to be smaller and defects are not improved. It tends to decrease. On the other hand, when R ₃ is a hydrogen atom, the thermal stability and storage stability of the polymer tend to be superior to those when R ₃ is a methyl group.
Further, n is preferably 1 from the viewpoint of reducing the molecular weight dispersion of the polymer of the present invention.

The polymer having the structural unit represented by the formula (2) is solubilized in an alkali developer or the like by being decomposed by the action of an acid. Conventional resist polymers have been solubilized in an alkaline developer by the removal of side-chain acid-eliminable leaving groups to form carboxyl groups. In contrast, the polymer of the present invention not only generates a carboxyl group by the decomposition of an acetal bond by an acid, but also breaks the cross-linked portion between the main chain and the main chain by the decomposition, so that the molecular weight is remarkably reduced after the decomposition. Therefore, the solubility in an alkaline developer is remarkably increased as compared with the conventional one. Therefore, such a polymer can be suitably used as a resist having a small line edge roughness.
In addition, since the acid-decomposable bond of the present invention has an acetal structure, it tends to have higher decomposability and lower line edge roughness than an acid-decomposable bond having a tertiary ester structure.

  The content of the structural unit represented by the formula (2) is not particularly limited, but is preferably in the range of 0.5 to 30 mol% in the structural units of the polymer. When the content of the structural unit represented by the formula (2) is 0.5 mol% or more, the line edge roughness tends to be small and defects tend to decrease, and the content is 30 mol% or less. In some cases, there are few defects and the solubility in an organic solvent tends to be good. The lower limit of this content is more preferably 3 mol% or more, and particularly preferably 5 mol% or more. Further, the upper limit of the content is more preferably 20 mol% or less, and particularly preferably 15 mol% or less.

The polymer of the present invention contains the structural unit represented by the formula (2), but when used as a resist polymer, it further contains a structural unit containing an acid leaving group. Is preferred.
The structural unit containing an acid leaving group of the present invention refers to a structural unit containing an acid leaving group in a side chain in a polymer.
Here, the acid leaving group is a group having a structure that is eliminated by the action of an acid, and the structural unit containing the acid leaving group is derived from an alkali-soluble group and an acid leaving group by being decomposed by an acid. It becomes the residue.

The acid leaving group is not particularly limited, but t-butyl group, methylcyclopentyl group, ethylcyclopentyl group, methyladamantyl group, ethyladamantyl, group methylcyclohexyl group, ethylcyclohexyl group, methyloxymethyl group, cyclopentyloxymethyl. Group, cyclohaesyloxymethyl group, 1-adamantyloxymethyl group, 2-adamantyloxymethyl group and the like. Of these, a methyladamantyl group, an ethylcyclohexyl group, and a cyclopentyloxymethyl group are preferable.
In order to introduce a structural unit having an acid leaving group into a polymer, a monomer having an acid leaving group is copolymerized with a polyfunctional (meth) acrylic acid ester represented by the above formula (1). Can be obtained. Although it does not restrict | limit especially as a monomer which has an acid leaving group, For example, the monomer represented by following formula (3) is mentioned.

(In the formula (3), R represents a hydrogen atom or a methyl group, and Z represents an acid leaving group.)

  Although it does not restrict | limit especially as a monomer represented by Formula (3), For example, the monomer represented by following formula (3-1)-(3-92) is mentioned. In the following formulas (3-1) to (3-92), R or R ′ represents a hydrogen atom or a methyl group.

Among the monomers having an acid leaving group represented by the formula (3), the monomer represented by the above formula (3-1), the single monomer represented by the above formula (3-2) Body, monomer represented by the above formula (3-5), monomer represented by the above formula (3-23), single unit represented by the above formulas (3-24) to (3-29) A monomer represented by the above formula (3-32), a monomer represented by the above formula (3-37), and a single monomer represented by the above formulas (3-42) to (3-45). The monomer and the monomer represented by the above formulas (3-57) to (3-58) are preferable in that high sensitivity and high resolution can be obtained.
As the monomer having an acid leaving group, in addition to the monomer represented by the formula (3), monomers represented by the following formulas (5-101) to (5-112) , Monomers represented by the following formulas (5-201) to (5-214), and monomers represented by the following formulas (5-301) to (5-313). In the monomers represented by the formulas (5-101) to (5-112), formulas (5-201) to (5-214), and the following formulas (5-301) to (5-313), R represents a hydrogen atom or a methyl group.

Among these structural units having an acid-eliminable group, a structural unit having an alicyclic skeleton, that is, an alicyclic skeleton having an acid-decomposable group, is required in terms of high dry etching resistance required for a resist. The structural unit it has is preferable. An alicyclic skeleton is a skeleton having a structure having one or more cyclic hydrocarbon groups. In such a structural unit, a cyclic hydrocarbon group is usually decomposed by the action of an acid.
The monomer which has an acid leaving group can be used 1 type, or 2 or more types as needed.

  The content of the structural unit having an acid leaving group is not particularly limited, but is preferably in the range of 10 to 60 mol% in the structural unit of the polymer. When the content of the structural unit having an acid leaving group is 10 mol% or more, the sensitivity and resolution tend to be improved. When the content is 60 mol% or less, the resolution is improved. Tend to improve. The lower limit of this content is more preferably 20 mol% or more, and particularly preferably 30 mol% or more. Further, the upper limit of the content is more preferably 55 mol% or less, and particularly preferably 50 mol% or less.

In addition to the structural unit having an acid leaving group, the polymer of the present invention may contain other structural unit as necessary.
For example, the polymer of the present invention can contain a structural unit having a lactone skeleton in order to impart adhesion to the substrate.
When the structural unit having a lactone skeleton has a protecting group that is decomposed by an acid, it tends to have better sensitivity. In addition, when the structural unit having a lactone skeleton has a high carbon density, that is, when the ratio of the number of carbon atoms to the total number of atoms in the structural unit is high, it tends to have better dry etching resistance.

In order to introduce a structural unit having a lactone skeleton into a polymer, a monomer having a lactone skeleton may be copolymerized. One or more monomers having a lactone skeleton can be used as necessary.
The monomer having a lactone skeleton is not particularly limited. For example, the monomer has a (meth) acrylic acid derivative having a δ-valerolactone ring, a (meth) acrylic acid derivative having a γ-butyrolactone ring, and a polycyclic lactone. Examples thereof include (meth) acrylic acid derivatives, 2-methylene-4-butanolide, and derivatives having a substituent on the lactone ring of these compounds.
Specific examples of the monomer having a lactone skeleton include the following formulas (10-1) to (10-34), the following formulas (10-101) to (10-120), and the following formulas (10-301) to And a monomer represented by (10-304). In formulas (10-1) to (10-34), R represents a hydrogen atom or a methyl group.

Among these monomers having a lactone skeleton, from the viewpoint of sensitivity, the monomer represented by the above formula (10-1), the monomer represented by the above formula (10-2), and the above formula The monomer represented by (10-34) or an optical isomer thereof is preferable.
From the viewpoint of dry etching resistance, the monomer represented by the above formula (10-6), the monomer represented by the above formula (10-10), and the above formula (10-14). The monomer represented by the above formula (10-18), the monomer represented by the above formula (10-21), or a geometric isomer or optical isomer thereof is preferable.
From the viewpoint of solubility in a resist solvent, the monomer represented by the above formula (10-7), the monomer represented by the above formula (10-11), and the above formula (10-15) A monomer represented by the above formula (10-19), a monomer represented by the above formulas (10-25) to (10-33), or a geometric isomer thereof. Or an optical isomer is preferable.
Further, from the viewpoint of line edge roughness, defect, and microgel, the above formulas (10-1), (10-2), or optical isomers thereof are particularly preferable.

  The content of the structural unit having a lactone skeleton is not particularly limited, but is preferably in the range of 5 to 50 mol% in the structural units of the polymer. When the content of the structural unit having a lactone skeleton is 5 mol% or more, the adhesion to the substrate tends to be good, and when this content is 50 mol% or less, defects tend to decrease. It is in. The lower limit of the content is more preferably 15 mol% or more, and particularly preferably 30 mol% or more. Further, the upper limit of the content is more preferably 45 mol% or less, and particularly preferably 40 mol% or less.

The polymer of the present invention may further contain structural units other than those described above. For example, a structural unit having an alicyclic skeleton having no acid-decomposable group (hereinafter referred to as a structural unit having an alicyclic skeleton) can be contained.
In order to introduce a structural unit having an alicyclic skeleton into a polymer, a monomer having an alicyclic skeleton may be copolymerized. One or more monomers having an alicyclic skeleton can be used as necessary.
Specific examples of the monomer having an alicyclic skeleton include monomers represented by the following formulas (13-1) to (13-122) and the following formulas (14-101) to (14-131). Can be mentioned. In formulas (13-1) to (13-122), R represents a hydrogen atom or a methyl group.

A polymer containing a structural unit having an alicyclic skeleton tends to be excellent in dry etching resistance. Furthermore, when these structural units have a hydroxyl group, a cyano group, or a —C (CF ₃ ) ₂ —OH group, a more excellent resist pattern shape tends to be obtained.
Among these monomers having an alicyclic skeleton, the monomer represented by the above formula (13-1), the above formulas (13-3) to (13-5), from the viewpoint of good resist pattern shape. ), Monomers represented by the above formulas (13-32) to (13-34), monomers represented by the above formulas (13-36) to (13-39) A monomer represented by the above formula (13-43), a monomer represented by the above formulas (13-58) to (13-61), or a geometric isomer or optical isomer thereof is preferable.

Further, from the viewpoint of good solubility in a resist solvent, a monomer represented by the above formula (13-6), a monomer represented by the above formulas (13-8) to (13-10), The monomer represented by the above formula (13-31), the monomer represented by the above formula (13-35), the monomer represented by the above formula (13-40), the above formula (13- 44), monomers represented by the above formulas (13-55) to (13-57), monomers represented by the above formulas (13-62) to (13-65) Or geometric isomers or optical isomers thereof.
Further, from the viewpoint of high dry etching resistance, monomers represented by the above formulas (13-118) to (13-122), or geometrical isomers or optical isomers thereof are more preferable.
Further, the monomer represented by the formula (13-1) or a geometric isomer or optical isomer thereof is particularly preferable in that the line edge roughness, the microgel, and the number of defects are small.

  The content of the structural unit having an alicyclic skeleton is not particularly limited, but is preferably in the range of 5 to 40 mol% in the structural units of the polymer. When the content of the structural unit having an alicyclic skeleton is 5 mol% or more, the resist pattern shape tends to be good, and when the content is 40 mol% or less, the microgel and the defect are It tends to be less. The lower limit of the content is more preferably 10 mol% or more, and particularly preferably 15 mol% or more. Further, the upper limit of the content is more preferably 35 mol% or less, and particularly preferably 30 mol% or less.

Furthermore, the polymer of the present invention can contain, for example, a structural unit having an aromatic ring that does not have an acid-decomposable group (hereinafter referred to as a structural unit having an aromatic ring).
A polymer containing a structural unit having an aromatic ring tends to be excellent in dry etching resistance. Furthermore, when these structural units have a hydroxyl group, a cyano group, or a —C (CF ₃ ) ₂ —OH group, a better resist pattern shape tends to be obtained.
In order to introduce a structural unit having an aromatic ring into the polymer, a monomer having an aromatic ring may be copolymerized. The monomer which has an aromatic ring can use 1 type (s) or 2 or more types as needed.
Specific examples of the monomer having an aromatic ring include monomers represented by the following formulas (15-201) to (15-211) and the following formulas (16-301) to (16-316). Can be mentioned. In formulas (15-201) to (15-211) and formulas (16-301) to (16-316), R represents a hydrogen atom or a methyl group.

  Although content of the structural unit which has an aromatic ring is not restrict | limited in particular, The range of 5-40 mol% in the structural unit of a polymer is preferable. When the content of the structural unit having an aromatic ring is 5 mol% or more, the etching resistance tends to be excellent, and when this content is 40 mol% or less, the defect tends to be reduced. The lower limit of the content is more preferably 10 mol% or more, and particularly preferably 20 mol% or more. Further, the upper limit of the content is more preferably 35 mol% or less, and particularly preferably 30 mol% or less.

Furthermore, the polymer of the present invention has, for example, a structural unit having a carboxylic acid or a carboxylic anhydride that does not have an acid-decomposable group and does not have an alicyclic skeleton (hereinafter referred to as a structural unit having a carboxylic acid). Can be contained. A polymer containing a structural unit having a carboxylic acid tends to have good solubility in an alkaline developer.
In order to introduce a structural unit having a carboxylic acid into the polymer, an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride may be copolymerized. One or more unsaturated carboxylic acids or unsaturated carboxylic anhydrides can be used as necessary.
Specific examples of the unsaturated carboxylic acid or unsaturated carboxylic acid anhydride include structural units represented by the following formulas (17-1) to (17-6). In formulas (17-1) to (17-6), R represents a hydrogen atom or a methyl group.

  Although content of the structural unit which has carboxylic acid is not restrict | limited in particular, the range of 0.01-5 mol% in the structural unit of a polymer is preferable. When the content of the structural unit having a carboxylic acid is 0.01 mol% or more, the dissolution in an alkali developer tends to be good, and the line edge roughness tends to be small, and the content is 5 mol% or less. In some cases, the etching resistance tends to be excellent. The lower limit of this content is more preferably 0.1 mol% or more, and particularly preferably 0.3 mol% or more. Further, the upper limit of this content is more preferably 2 mol% or less, and particularly preferably 1 mol% or less.

  In addition to the above-described monomers, other copolymerizable monomers can be copolymerized as necessary. Examples thereof include monomers represented by the following formulas (18-1) to (18-5). These monomers can be used alone or in combination of two or more.

  In addition to the above monomers, for example, methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-propyl (meth) acrylate, (meth) acrylic acid Isopropyl, butyl (meth) acrylate, isobutyl (meth) acrylate, n-propoxyethyl (meth) acrylate, iso-propoxyethyl (meth) acrylate, n-butoxyethyl (meth) acrylate, (meth) acryl Iso-butoxyethyl acid, tert-butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxy-n-propyl (meth) acrylate, ( (Meth) acrylic acid 4-hydroxy-n-butyl, (meth) acrylic acid 2-ethoxyethyl , (Meth) acrylic acid 1-ethoxyethyl, (meth) acrylic acid 2,2,2-trifluoroethyl, (meth) acrylic acid 2,2,3,3-tetrafluoro-n-propyl, (meth) acrylic Acid 2,2,3,3,3-pentafluoro-n-propyl, methyl α- (tri) fluoromethyl acrylate, ethyl α- (tri) fluoromethyl acrylate, α- (tri) fluoromethyl acrylic acid 2 -Ethylhexyl, n-propyl α- (tri) fluoromethyl acrylate, iso-propyl α- (tri) fluoromethyl acrylate, n-butyl α- (tri) fluoromethyl acrylate, α- (tri) fluoromethyl acryl Iso-butyl acid, tert-butyl α- (tri) fluoromethyl acrylate, methoxymethyl α- (tri) fluoromethyl acrylate, α- (to R) Ethoxyethyl fluoromethyl acrylate, n-propoxyethyl α- (tri) fluoromethyl acrylate, iso-propoxyethyl α- (tri) fluoromethyl acrylate, n-butoxyethyl α- (tri) fluoromethyl acrylate , (Meth) acrylic acid esters having a linear or branched structure, such as iso-butoxyethyl α- (tri) fluoromethyl acrylate, tert-butoxyethyl α- (tri) fluoromethyl acrylate, etc. it can. These monomers can be used alone or in combination of two or more.

  The mass average molecular weight (Mw) of the polymer of the present invention is not particularly limited, but is preferably 1,000 or more, more preferably 2,000 or more, from the viewpoint of dry etching resistance and resist shape. It is especially preferable that it is 4,000 or more. Further, the mass average molecular weight of the polymer of the present invention is preferably 100,000 or less, more preferably 50,000 or less, and more preferably 30,000 or less, from the viewpoints of solubility in a resist solution and resolution. It is particularly preferred.

In addition, the mass average molecular weight here is measured under the following conditions.
Apparatus: Tosoh gel permeation chromatography (GPC) apparatus HLC-8220
Separation column: manufactured by Showa Denko KK, Shodex GPC K-805L (trade name) in series 3 Solvent: tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Detector: Differential refractometer Measurement temperature: 40 ° C
Injection volume: 0.1 mL
Standard polymer: Polystyrene sample solution: About 20 mg of the polymer was dissolved in 5 mL of THF, and filtered through a 0.5 μm membrane filter to prepare a sample solution.

Next, the manufacturing method of the polymer of this invention is demonstrated.
The method for producing the polymer of the present invention is not particularly limited, but is preferably obtained by radical polymerization of the monomer composition in the presence of a polymerization initiator. It can manufacture at low cost by polymerizing by radical polymerization. Moreover, the polymer obtained has few foreign substances and tends to obtain a highly transparent polymer.
In radical polymerization, first, a polymerization initiator is decomposed by heat or the like to generate a radical, and monomer chain polymerization proceeds from this radical as a starting point.

  As the polymerization initiator used in the production of the polymer of the present invention, those that generate radicals efficiently by heat are preferable. Examples of such a polymerization initiator include 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazoline- Azo compounds such as 2-yl) propane; and organic peroxides such as 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane.

In addition, when the polymer of the present invention is used as a resist polymer particularly used in ArF excimer laser (wavelength: 193 nm) lithography, the light transmittance of the resulting resist polymer (transmittance to light having a wavelength of 193 nm). ) Is not reduced as much as possible, and the polymerization initiator used preferably has no aromatic ring in the molecular structure. Furthermore, in consideration of safety during polymerization, the polymerization initiator used preferably has a 10-hour half-life temperature of 60 ° C. or higher.
Although the amount of the polymerization initiator used is not particularly limited, it is preferably 0.1 mol% or more based on the total amount of monomers used for the polymerization in order to increase the yield of the polymer, and the molecular weight distribution of the polymer is determined. From the point of narrowing, 30 mol% or less is preferable with respect to the total amount of monomers used for polymerization. The amount of the polymerization initiator used is more preferably 0.3 mol% or more, and particularly preferably 1 mol% or more.

In producing the polymer of the present invention, a chain transfer agent may be used.
The chain transfer agent is not particularly limited, but when the polymer of the present invention is used as a resist polymer used in ArF excimer laser (wavelength: 193 nm) lithography, the light transmittance of the resulting resist polymer. From the viewpoint of not reducing (transmittance with respect to light having a wavelength of 193 nm) as much as possible, those having no aromatic ring are preferable.
Suitable chain transfer agents include, for example, 1-butanethiol, 2-butanethiol, 1-octanethiol, 1-decanethiol, 1-tetradecanethiol, cyclohexanethiol, 2-methyl-1-propanethiol, 2-mercapto Thiols such as ethanol, 1-thioglycerol and mercaptoacetic acid are preferred.

In the radical polymerization reaction, a polymer having a radical at the growth end is generated. However, when a chain transfer agent is used, the radical at the growth end pulls out the hydrogen of the chain transfer agent, and the growth end becomes a deactivated polymer. On the other hand, the chain transfer agent from which hydrogen has been extracted becomes a structure having a radical, that is, a radical body, and the monomer is chain-polymerized again starting from this radical body. When a bifunctional chain transfer agent is used, polymerization proceeds from each functional group, and thus a chain transfer residue is incorporated into the main chain of the obtained polymer. In the anionic polymerization reaction, it is possible to incorporate a chain transfer agent residue into the polymer by adding a chain transfer agent at the end of the polymerization.
Although the usage-amount of a chain transfer agent is not specifically limited, 0.001-30 mol% is preferable with respect to the monomer whole quantity used for superposition | polymerization, and 0.01-2 mol% is more preferable.

The method for producing the polymer of the present invention is not particularly limited, but a solution polymerization method is preferred. Among them, from the viewpoint that a polymer having a narrow composition distribution and / or molecular weight distribution can be easily obtained, a monomer (a monomer alone or a solution obtained by dissolving a monomer in an organic solvent may be used. ) Is preferably dropped into the polymerization vessel (so-called dropping polymerization method).
The polymerization temperature in the dropping polymerization method is not particularly limited, but is preferably in the range of 50 to 150 ° C.

Although it does not restrict | limit especially as an organic solvent used in the dropping polymerization method, The solvent which can melt | dissolve all of the chain transfer agent when using the monomer to be used, a polymerization initiator, the polymer obtained, and also a chain transfer agent. Is preferred.
Examples of such an organic solvent include 1,4-dioxane, isopropyl alcohol, acetone, tetrahydrofuran (hereinafter referred to as “THF”), methyl ethyl ketone (hereinafter referred to as “MEK”), and methyl isobutyl ketone (hereinafter referred to as “MIBK”). ), Γ-butyrolactone, propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”), ethyl lactate and the like.
The monomer concentration of the monomer solution dropped into the organic solvent is not particularly limited, but is preferably in the range of 5 to 50% by mass.
The amount of the organic solvent charged into the polymerization vessel is not particularly limited and may be determined as appropriate. Usually, it uses within the range of 30-700 mass parts with respect to 100 mass parts of monomers used for superposition | polymerization.

The polymer solution produced by a method such as solution polymerization can be prepared with a good solvent viscosity such as 1,4-dioxane, acetone, THF, MEK, MIBK, γ-butyrolactone, PGMEA, and ethyl lactate as necessary. Then, it is dropped into a large amount of poor solvent such as methanol or water to precipitate the polymer. This process is generally called reprecipitation and is very effective for removing unreacted monomers, polymerization initiators, and the like remaining in the polymerization solution. If these unreacted substances remain as they are, there is a possibility of adversely affecting the resist performance. Therefore, it is preferable to remove them as much as possible. The reprecipitation process may be unnecessary depending on circumstances.
After the reprecipitation step, the precipitate can be filtered and sufficiently dried to obtain the polymer of the present invention. Moreover, after filtering off, it can also be used with a wet powder, without drying.
Further, the produced polymer solution can be used as a resist composition as it is or after being diluted with an appropriate solvent. At that time, additives such as a storage stabilizer may be appropriately added.

Next, the resist composition of the present invention will be described.
The resist composition of the present invention is obtained by dissolving the above-described polymer of the present invention in a solvent. 1 type may be used for the polymer of this invention and it may use 2 or more types together. In addition, without separating the polymer from the polymer solution obtained by solution polymerization or the like, the polymer solution can be used as it is for the resist composition, or the polymer solution can be diluted with an appropriate solvent to form a resist composition. It can also be used for things.
In the resist composition of the present invention, the solvent for dissolving the polymer of the present invention is arbitrarily selected according to the purpose, but the selection of the solvent is for reasons other than the solubility of the resin, for example, the uniformity of the coating film, the appearance Or there may be restrictions from safety.

  The solvent used in the resist composition is not particularly limited. For example, linear or branched ketones such as methyl ethyl ketone, methyl isobutyl ketone and 2-pentanone; cyclic ketones such as cyclopentanone and cyclohexanone; propylene glycol monomethyl ether Propylene glycol monoalkyl acetates such as acetate; Ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate; Propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether; Ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether Diethylene glycol alkyl ethers such as diethylene glycol dimethyl ether; ethyl acetate; Esters such as ethyl; n-propyl alcohol, isopropyl alcohol, n- butyl alcohol, tert- butyl alcohol; 1,4-dioxane, ethylene carbonate, .gamma.-butyrolactone. These solvents may be used alone or in combination of two or more.

  Although content in particular of a solvent is not restrict | limited, 200 mass parts or more are preferable with respect to 100 mass parts of polymers, and 300 mass parts or more are more preferable. Moreover, the upper limit of content of a solvent is although it does not restrict | limit in particular, 5000 mass parts or less are preferable with respect to 100 mass parts of polymers, and 2000 mass parts or less are more preferable.

When the resist composition of the present invention is used for a chemically amplified resist, it is necessary to use a photoacid generator.
The photoacid generator can be arbitrarily selected from those that can be used as the acid generator of the chemically amplified resist composition. 1 type may be used for a photo-acid generator, and it may use 2 or more types together.
Examples of such a photoacid generator include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, diazomethane compounds, and the like. Among them, onium salt compounds such as sulfonium salt, iodonium salt, phosphonium salt, diazonium salt, pyridinium salt are preferable. Specifically, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, ( Hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate, diphenyliodonium hexafluoroantimonate, p-methylphenyldiphenylsulfonium nonafluorobutanesulfonate, tri (tert-butylphenyl) Sulfonium trifluoromethanesulfonate Etc. The.

  Although content of a photo-acid generator is suitably determined by the kind of selected photo-acid generator, 0.1 mass part or more is preferable with respect to 100 mass parts of polymers, and 0.5 mass part or more is more preferable. . By setting the content of the photoacid generator within this range, a chemical reaction due to the catalytic action of the acid generated by exposure can be sufficiently caused. The upper limit of the content of the photoacid generator is not particularly limited, but is preferably 20 parts by mass or less and more preferably 10 parts by mass or less with respect to 100 parts by mass of the polymer. By setting the content of the photoacid generator within this range, the stability of the resist composition is improved, and there is a tendency that the occurrence of uneven coating during application of the composition, scum during development, etc. is sufficiently reduced. .

Furthermore, a nitrogen-containing compound can also be mix | blended with a chemically amplified resist composition. By containing a nitrogen-containing compound, the resist pattern shape, the stability over time, and the like tend to be further improved. In other words, the cross-sectional shape of the resist pattern is closer to a rectangle, and the resist film is exposed, post-exposure baked (PEB), and left for several hours before the next development process. However, there is a tendency that the deterioration of the cross-sectional shape of the resist pattern is more suppressed when left as such (timed).
As the nitrogen-containing compound, any known compounds can be used, but amines are preferable, and among them, secondary lower aliphatic amines and tertiary lower aliphatic amines are more preferable.
Here, the “lower aliphatic amine” refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms.

Examples of the secondary lower aliphatic amine and tertiary lower aliphatic amine include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine and the like. Is mentioned. Among these nitrogen-containing compounds, tertiary alkanolamines such as triethanolamine are more preferable.
The nitrogen-containing compound may be used alone or in combination of two or more. The content of the nitrogen-containing compound is appropriately determined depending on the type of the selected nitrogen-containing compound, but is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the polymer. By setting the content of the nitrogen-containing compound within this range, the resist pattern shape tends to be more rectangular. The upper limit of the content of the nitrogen-containing compound is not particularly limited, but is preferably 2 parts by mass or less with respect to 100 parts by mass of the polymer. By setting the content of the nitrogen-containing compound within this range, the sensitivity deterioration tends to be reduced.

The chemically amplified resist composition may also contain an organic carboxylic acid, a phosphorus oxo acid, or a derivative thereof. By containing these compounds, it is possible to prevent sensitivity deterioration due to the compounding of the nitrogen-containing compound, and there is a tendency that the resist pattern shape, the stability over time and the like are further improved.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are preferable.
Phosphorus oxoacids or derivatives thereof include, for example, phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid and derivatives thereof; phosphonic acid, phosphonic acid dimethyl ester Phosphonic acids such as phosphonic acid di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester, etc. and derivatives thereof; phosphinic acids such as phosphinic acid, phenylphosphinic acid and their Examples thereof include derivatives such as esters, and among them, phosphonic acid is preferable.

These compounds (organic carboxylic acid, phosphorus oxo acid, or derivatives thereof) may be used alone or in combination of two or more.
The content of these compounds (organic carboxylic acid, phosphorus oxo acid or derivative thereof) is appropriately determined depending on the type of the selected compound, etc., but 0.01 parts by mass or more with respect to 100 parts by mass of the polymer. It is preferable that By setting the content of these compounds within this range, the resist pattern shape tends to be more rectangular. Further, the upper limit of the content of these compounds (organic carboxylic acid, phosphorus oxoacid or derivative thereof) is not particularly limited, but is preferably 5 parts by mass or less with respect to 100 parts by mass of the polymer. . By setting the content of these compounds within this range, there is a tendency that the film loss of the resist pattern can be reduced.
Note that both the nitrogen-containing compound and the organic carboxylic acid, phosphorus oxoacid, or a derivative thereof can be contained in the chemically amplified resist composition of the present invention, or only one of them can be contained. .

Furthermore, the resist composition of the present invention may contain various additives such as surfactants, other quenchers, sensitizers, antihalation agents, storage stabilizers, and antifoaming agents as necessary. it can. Any of these additives can be used as long as it is known in the art. Moreover, the compounding quantity of these additives is not specifically limited, What is necessary is just to determine suitably.
The resist composition of the present invention can be used as a resist composition for semiconductors, metal etching, photofabrication, plate making, holograms, color filters, retardation films and the like.

Next, the manufacturing method of the board | substrate with which the pattern of this invention was formed is demonstrated.
First, the resist composition of the present invention is applied to the surface of a substrate to be processed such as a silicon wafer on which a pattern is formed by spin coating or the like. And the to-be-processed board | substrate with which this resist composition was apply | coated is dried by baking process (prebaking) etc., and a resist film is formed on a board | substrate.
Next, the resist film thus obtained is irradiated with light having a wavelength of 250 nm or less through a photomask (exposure). The light used for exposure is preferably a KrF excimer laser, an ArF excimer laser, or an F ₂ excimer laser, and particularly preferably an ArF excimer laser. It is also preferable to expose with an electron beam.

After the exposure, heat treatment is appropriately performed (post-exposure baking, PEB), the substrate is immersed in an alkaline developer, and the exposed portion is dissolved and removed in the developer (development). Any known alkaline developer may be used. Then, after development, the substrate is appropriately rinsed with pure water or the like. In this way, a resist pattern is formed on the substrate to be processed.
Usually, a substrate to be processed on which a resist pattern is formed is appropriately heat-treated (post-baked) to strengthen the resist, and a portion without the resist is selectively etched. After etching, the resist is usually removed using a release agent. In this way, a substrate on which a pattern is formed can be manufactured.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. Further, “parts” in the examples and comparative examples means “parts by mass” unless otherwise specified.
In addition, polyfunctional (meth) acrylic acid esters, polymers, and resist compositions were evaluated as follows.

(1) Evaluation of polyfunctional (meth) acrylic acid ester <Thermal stability of polyfunctional (meth) acrylic acid ester>
The thermal stability of the polyfunctional (meth) acrylic acid ester monomer was determined by measuring ¹ H-NMR after stirring 3.0 g of the monomer at 100 ° C. for 4 hours, and before heating and stirring. Specifically, deuterated chloroform is added to the monomer before or after heating and stirring to make a solution of about 5% by mass, and this solution is put into a test tube having a diameter of 5 mmφ, JN GX, manufactured by JEOL Ltd. Using -270 FT-NMR (trade name), ¹ H-NMR measurement was performed by performing 64 integrations at a measurement temperature of 40 ° C., an observation frequency of 270 MHz, and a single pulse mode.
The thermal stability was evaluated by how much the ratio of oxygen in the acetal structure and the hydrogen bonded to the carbon sandwiched between the oxygens did not change.
Thermal stability = {(integral value of oxygen after pyrolysis test and hydrogen bonded to carbon sandwiched between oxygen) / (total integral value between chemical shift δ value 3.0 to 5.0 ppm after pyrolysis test) )} / {(Integral value of oxygen bonded to carbon sandwiched between oxygen and oxygen before thermal decomposition test) / (total integrated value between chemical shift δ value 3.0 to 5.0 ppm before thermal decomposition test) )}
The closer this value is to 1, the higher the thermal stability of the acetal structure, and the smaller the value, the lower the thermal stability of the acetal structure.

(2) Evaluation of polymer <Thermal stability of polymer>
The thermal stability of the polymer was determined by measuring ¹ H-NMR of 3.0 g of the polymer by heating and stirring at 100 ° C. for 4 hours, and before heating and after heating and stirring. Specifically, the polymer before or after heating and stirring is dissolved in deuterated chloroform to obtain a solution of about 5% by mass, and this solution is put into a test tube having a diameter of 5 mmφ, manufactured by JEOL Ltd., Using JN GX-270 type FT-NMR (trade name), integration was performed 64 times at a measurement temperature of 40 ° C., an observation frequency of 270 MHz, and a single pulse mode, and ¹ H-NMR was measured.
The thermal stability was evaluated by how much the ratio of oxygen in the acetal structure and the hydrogen bonded to the carbon sandwiched between the oxygens did not change.
Thermal stability = {(integral value of oxygen after pyrolysis test and hydrogen bonded to carbon sandwiched between oxygen) / (total integral value between 0 and 2.6 ppm of chemical shift δ value after pyrolysis test)} / {(Oxygen before thermal decomposition test and integral value of hydrogen bonded to carbon sandwiched between oxygen) / (Total integrated value between chemical shift δ value 0 to 2.6 ppm before thermal decomposition test)}
The closer this value is to 1, the higher the thermal stability of the acetal structure, and the smaller the value, the lower the thermal stability of the acetal structure.

<Average copolymer composition ratio of polymer (mol%)>
The average copolymer composition ratio of the polymer was determined by ¹ H-NMR measurement. Specifically, the polymer is dissolved in deuterated chloroform to make a solution of about 5% by mass. This solution is put in a test tube having a diameter of 5 mmφ, and manufactured by JEOL Co., Ltd., GSX-400 type FT-NMR ( (Trade name) was used, and the integration was performed 64 times in a single pulse mode at a measurement temperature of 40 ° C., an observation frequency of 400 MHz, and ¹ H-NMR was measured.

<Mass average molecular weight of polymer>
About 20 mg of the polymer was dissolved in 5 mL of THF and filtered through a 0.5 μm membrane filter to prepare a sample solution. This sample solution was prepared by using a gel permeation chromatography (GPC) apparatus manufactured by Tosoh: HLC-8220. And measured. For this measurement, a separation column was manufactured by Showa Denko Co., Ltd., Shodex GPC K-805L (trade name) in series, the solvent was THF, the flow rate was 1.0 mL / min, the detector was a differential refractometer, measurement Measurements were made using polystyrene as the standard polymer at a temperature of 40 ° C. and an injection volume of 0.1 mL.

(3) Evaluation of resist composition <Sensitivity>
The exposure amount (mJ / cm ² ) at which a 0.16 μm line-and-space pattern mask was transferred to a line width of 0.16 μm was measured as sensitivity.
<Resolution>
The minimum dimension (μm) of the resist pattern resolved when exposed at the exposure amount was defined as the resolution.

<Line edge roughness>
JSM-6340F field emission scanning electron microscope manufactured by JEOL Ltd. with respect to a range of 5 μm on the side edge in the longitudinal direction of the 0.20 μm resist pattern obtained by the minimum exposure amount reproducing the 0.20 μm resist pattern on the mask Based on (product name), the distance from the reference line where the pattern side edge should be was measured at 50 points, the standard deviation was obtained, and 3σ was calculated as an index of line edge roughness. A smaller value indicates better performance.
<Defect amount>
With respect to the resist pattern obtained as described above, the number of development defects was measured with a surface defect observation apparatus KLA2132 manufactured by KLA Tencor.

Example 1
In a 200 ml flask, 50.3 g of 2- (vinyloxyethoxy) ethyl acrylate represented by the following formula (20) was charged, heated to 60 ° C. and stirred. Acrylic acid 29.2g was dripped at this over 1 hour, and it was made to age | cure | ripen after that for 3 hours. After cooling to room temperature and adding 80 ml of toluene, it was washed twice with 80 ml of saturated aqueous sodium bicarbonate. After concentrating the organic layer, the concentrate was subjected to thin-film distillation under reduced pressure to obtain 52.8 g of a polyfunctional acrylic ester represented by the following formula (M-1). Table 1 shows the evaluation results of thermal stability.

Example 2
In a 200 ml flask, 50.2 g of 2- (vinyloxyethoxy) ethyl methacrylate represented by the following formula (21) was charged, heated to 90 ° C. and stirred. To this, 32.3 g of methacrylic acid was added dropwise over 1 hour and then aged for 4 hours. After cooling to room temperature and adding 80 ml of toluene, it was washed 3 times with 80 ml of saturated aqueous sodium bicarbonate. After the organic layer was concentrated, the concentrate was subjected to thin-film distillation under reduced pressure to obtain 55.3 g of a polyfunctional methacrylate represented by the following formula (M-2). Table 1 shows the evaluation results of thermal stability.

Comparative Example 1
In a 300 ml flask, 25.0 g of ethylene glycol divinyl ether represented by the following formula (22) and a small amount of 4-t-butylcatechol were charged, heated to 70 ° C. and stirred. To this was added dropwise 36.5 g of methacrylic acid over 20 minutes, and then aged for 6 hours. After cooling to room temperature and adding 80 ml of toluene, the reaction solution was subjected to thin-film distillation under reduced pressure to obtain 55.3 g of a polyfunctional methacrylate represented by the following formula (M-3). Table 1 shows the evaluation results of thermal stability. The evaluation result of thermal stability was 0.97, and the thermal stability was low.

Example 3
Under a nitrogen atmosphere, 39.0 parts of PGMEA was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping device, and a thermometer, and the temperature of the hot water bath was raised to 80 ° C. while stirring.
13.3 parts of α-methacryloyloxy-γ-butyrolactone (hereinafter referred to as GBLMA) represented by the following formula (51);
19.2 parts of 2-methacryloyloxy-2-methyladamantyl (hereinafter referred to as MAdMA) represented by the following formula (52);
9.4 parts of 1-methacryloyloxy-3-hydroxyadamantyl (hereinafter referred to as HAdMA) represented by the following formula (53);
5.2 parts of a polyfunctional acrylic ester represented by the following formula (M-1),
A monomer solution in which 68.8 parts of PGMEA and 1.31 parts of 2,2′-azobisisobutyronitrile (hereinafter referred to as AIBN) were mixed was dropped into the flask at a constant rate over 6 hours. Then, the temperature of 80 degreeC was hold | maintained for 1 hour. Next, the obtained reaction solution was added dropwise to about 10 times amount of methanol with stirring to obtain a white precipitate (polymer A-1). The resulting precipitate was filtered off and dried under reduced pressure at 60 ° C. for about 40 hours. Table 2 shows the results obtained by measuring the physical properties of the obtained polymer A-1.

100 parts of the obtained polymer, 2 parts of triphenylsulfonium triflate as a photoacid generator, and 700 parts of PGMEA as a solvent were mixed to obtain a uniform solution, and then filtered through a membrane filter having a pore size of 0.1 μm. A resist composition solution was prepared.
The prepared resist composition solution was spin coated on a silicon wafer (diameter: 200 mm), and prebaked at 120 ° C. for 60 seconds using a hot plate to form a resist film having a thickness of 0.4 μm. Next, after exposure using an ArF excimer laser exposure machine (wavelength: 193 nm), post-exposure baking was performed using a hot plate at 120 ° C. for 60 seconds. Subsequently, development was performed at room temperature using a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with pure water, and dried to form a resist pattern.
The evaluation results of the resist composition are shown in Table 2.

Example 4
Instead of the polyfunctional acrylate represented by the formula (M-1), 5.2 parts of the polyfunctional methacrylic ester represented by the formula (M-2) is used, and instead of HAdMA, the following formula (54) is used. A polymer A-2 was obtained in the same manner as in Example 3, except that 8.2 parts of the represented cyanonorbornane methacrylate (hereinafter referred to as CNNMA) was used. Table 2 shows the results of measurement of physical properties of the obtained polymer A-2.
Moreover, except having used obtained polymer A-2, operation similar to Example 3 was performed and the resist composition was obtained, and the resist pattern was formed. The evaluation results are shown in Table 2.

Comparative Example 2
The same as Example 3 except that 5.2 parts of the polyfunctional methacrylate represented by the formula (M-3) was used instead of the polyfunctional acrylic ester represented by the formula (M-1). Operation was performed to obtain a polymer A-3. Table 2 shows the results of measurement of physical properties of the obtained polymer A-3.
Moreover, except having used obtained polymer A-3, operation similar to Example 3 was performed and the resist composition was obtained, and the resist pattern was formed. The evaluation results are shown in Table 2. The evaluation result of thermal stability was 0.98, and the thermal stability was low.

  The polyfunctional (meth) acrylic acid ester of the present invention is not only useful as a raw material for resins used in resist compositions, but also used in paints, adhesives, pressure-sensitive adhesives, ink resins, molding materials, optical materials, etc. It is useful as a raw material. The polymer of the present invention is useful not only for resist compositions but also for resins used in paints, adhesives, pressure-sensitive adhesives, ink resins, molding materials, optical materials, and the like.

Claims (4)

The resist material which consists of a polymer which contains the structural unit represented by following formula (2) in 0.5 mol%-30 mol% in the structural unit of a polymer.
(In formula (2), R ₁ , R ₂ and R ₃ each independently represents a hydrogen atom or a methyl group, and A represents an alkylene group which may have a substituent, or a cyclo which may have a substituent. Represents an alkylene group, an oxyalkylene group which may have a substituent, a polyoxyalkylene group which may have a substituent, or an arylene group which may have a substituent, and m and n are each independently 0 or 1 and the structure of —O—A— (O) _m — has no acetal structure.) From the polymer which contains the structural unit represented by following formula (2) in the range of 0.5 mol%-30 mol% in the structural unit of a polymer, and also contains the structural unit which has an acid leaving group. The resist material according to claim 1.
(In formula (2), R ₁ , R ₂ and R ₃ each independently represents a hydrogen atom or a methyl group, and A represents an alkylene group which may have a substituent, or a cyclo which may have a substituent. Represents an alkylene group, an oxyalkylene group which may have a substituent, a polyoxyalkylene group which may have a substituent, or an arylene group which may have a substituent, and m and n are each independently 0 or 1 and the structure of —O—A— (O) _m — has no acetal structure.)   A resist composition containing the polymer according to claim 1. And having the steps of applying a composition comprising a billing resist composition claim 3, wherein the photoacid generator on the substrate to be processed, a step of exposing, and a step of developing with a developer A method for manufacturing a substrate on which a pattern is formed.