JP2006003846A - Chemically amplified photoresist polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a resist pattern having high resolution and low LER (Line Edge Roughness). <P>SOLUTION: In the chemically amplified photoresist polymer which contains a structural unit (a4) expressed by general formula (I), in the formula (I), R<SP>1</SP>represents a hydrogen atom or a methyl group, R<SP>2</SP>represents a 1-20C straight chain, branched or cyclic hydrocarbon group, each of R<SP>3</SP>, R<SP>4</SP>, R<SP>5</SP>, R<SP>6</SP>independently represents a hydrogen atom or a 1-6C straight or branched alkyl group, R<SP>7</SP>represents a 1-20C straight, branched or cyclic alkylene group, alkylene ether group, cyclohexylene group or arylene group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chemically amplified photoresist polymer.

With the miniaturization of semiconductor elements, development of lithography processes using, for example, an ArF excimer laser (193 nm) has been vigorously advanced. As the base resin of the chemically amplified resist for ArF excimer laser, a resin having high transparency with respect to ArF excimer laser is preferable.
For example, a resin having a structural unit derived from a (meth) acrylic acid ester having a polycyclic hydrocarbon group such as an adamantane skeleton in the ester portion has attracted attention, and many proposals have been made so far. (Patent Document 1 below).
Japanese Patent No. 2881969

  In recent years, with the rapid miniaturization of semiconductor elements, higher resolution is required. However, LER (Line Edge Roughness) has become a serious problem with the miniaturization of resist patterns.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a technique capable of forming a resist pattern with high resolution and low LER.

  In order to achieve the above object, the chemically amplified photoresist polymer of the present invention has a structural unit (a4) represented by the following formula (I).

（式中、Ｒ¹は水素原子又はメチル基であり、Ｒ²は炭素数１〜２０個の直鎖状、分岐状又は環状の炭化水素基であり、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶は各々独立して水素原子又は炭素数１〜６の直鎖状又は分岐状のアルキル基を表し、Ｒ⁷は炭素数１〜２０の直鎖状、分岐状または環状のアルキレン基、アルキレンエーテル基、シクロへキシレン基またはアリーレン基を表す。）

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, and R ³ , R ⁴ , R ⁵ , R ⁶ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁷ is a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, alkylene ether Group, a cyclohexylene group or an arylene group.)

In the present specification, “(α-lower alkyl) acrylic acid ester” means one or both of an α-lower alkyl acrylic acid ester such as methacrylic acid ester and an acrylic acid ester. Here, the “α-lower alkyl acrylate ester” means that a hydrogen atom bonded to the α carbon atom of the acrylate ester is substituted with a lower alkyl group.
“Constituent unit” means a monomer unit constituting a polymer. In the present invention, a structure in which monomer units are cross-linked is also referred to as “structural unit”.
The “structural unit derived from (α-lower alkyl) acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylate ester.
In the “(α-lower alkyl) acrylic acid” and “(α-lower alkyl) acrylic acid ester”, the “lower alkyl group” is preferably a straight chain having 1 to 5 carbon atoms unless otherwise specified. A branched alkyl group, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, etc. Groups are preferred.

  According to the present invention, a polymer that can be suitably used for a chemically amplified photoresist is obtained. According to the positive resist composition using this polymer as a resin component, a resist pattern with high resolution and low LER can be realized.

  Hereinafter, the present invention will be described in detail.

[Polymer for chemically amplified photoresist]
The chemically amplified photoresist polymer (A1) of the present invention (hereinafter sometimes referred to as component (A1)) has a structural unit (a4) represented by the following general formula (I).

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, and R ³ , R ⁴ , R ⁵ , R ⁶ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁷ is a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, alkylene ether Group, a cyclohexylene group or an arylene group.)

In addition to (a4), component (A1) may have a structural unit selected from the following structural units (a1), (a2), (a3) and (a5). In particular, it is preferable to have the structural units (a1), (a2), and (a3).
(A1): A structural unit derived from a mono (α-lower alkyl) acrylic ester containing an acid dissociable, dissolution inhibiting group.
(A2): A structural unit derived from a mono (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group.
(A3): A structural unit derived from a mono (α-lower alkyl) acrylate ester having a polycyclic alicyclic hydrocarbon group containing a hydroxyl group.
(A5): Structural unit (a5) other than structural units (a1) to (a4)

Here, “mono” of mono (α-lower alkyl) acrylate means having one (α-lower alkyl) acrylate residue.
“Poly” in a poly (α-lower alkyl) acrylate ester has two or more (α-lower alkyl) acrylate ester residues as in the structural unit represented by the general formula (I). means.
In the component (A1), both the structural unit derived from mono (α-lower alkyl) acrylate ester and the structural unit derived from poly (α-lower alkyl) acrylate ester are ethylenic diene. A polymer is formed by bonding with other adjacent structural units by cleavage of a heavy bond.

..Structural unit (a1)
The structural unit (a1) is a structural unit derived from a mono (α-lower alkyl) acrylic ester containing an acid dissociable, dissolution inhibiting group.
As the acid dissociable, dissolution inhibiting group, for example, a conventionally known one can be used and is not particularly limited.

As the structural unit (a1), for example, a structural unit derived from a mono (α-lower alkyl) acrylate ester containing a monocyclic or polycyclic group-containing acid dissociable dissolution inhibiting group, a chain acid dissociable dissolution inhibiting group Any of structural units derived from mono (α-lower alkyl) acrylic acid esters containing
The acid dissociable, dissolution inhibiting group is generally known to form a chain or cyclic tertiary alkyl ester with a side chain carboxyl group of (α-lower alkyl) acrylic acid. In particular, those containing a cyclic, monocyclic or polycyclic alicyclic hydrocarbon group, particularly preferably a polycyclic alicyclic hydrocarbon group are preferred. The hydrocarbon group is preferably saturated.

Examples of the monocyclic alicyclic hydrocarbon group include groups obtained by removing one hydrogen atom from cycloalkane and the like. Specific examples include groups in which one hydrogen atom has been removed from cyclohexane, cyclopentane, or the like.
Examples of the polycyclic alicyclic hydrocarbon group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Of these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable.

Examples of the mono (α-lower alkyl) acrylic acid ester (monomer) containing a chain acid dissociable, dissolution inhibiting group that induces the structural unit (a1) include the following.
For example, tert-butyl (meth) acrylate, tert-amyl (meth) acrylate, tert-butyloxycarbonylmethyl (meth) acrylate, tert-amyloxycarbonylmethyl (meth) acrylate, tert-butyloxycarbonylethyl (meth) acrylate , Tert-amyloxycarbonylethyl (meth) acrylate, and the like. Of these, tert-butyl (meth) acrylate is particularly preferred.

  Specific examples of the structural unit (a1) derived from a mono (α-lower alkyl) acrylate ester (monomer) containing a monocyclic or polycyclic group-containing acid dissociable, dissolution inhibiting group include 1-methylcyclopentyl (meta ) A structural unit constituted by cleavage of ethylenic double bond of acrylate, a structural unit constituted by cleavage of ethylenic double bond of 1-ethylcyclopentyl (meth) acrylate, 1-methylcyclohexyl (meth) acrylate A structural unit constituted by cleavage of an ethylenic double bond, a structural unit constituted by cleavage of an ethylenic double bond of 1-ethylcyclohexyl (meth) acrylate, the following general formula (aI-1), ( Examples include structural units represented by aI-2) and (aI-3).

(In the formula, R ²⁹ is a hydrogen atom or a linear or branched lower alkyl group, and R ³⁰ is a linear or branched lower alkyl group.)

(Wherein R ²⁹ is a hydrogen atom or a linear or branched lower alkyl group, and R ³⁵ and R ³⁶ are each independently a linear or branched lower alkyl group.)

(In the formula, R ²⁹ is a hydrogen atom or a linear or branched lower alkyl group, and R ³⁷ is a tertiary alkyl group.)

The lower alkyl group (α-lower alkyl group) as R ²⁹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, and n-butyl. Group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.
In general formula (aI-1), R ³⁰ is preferably a lower linear or branched alkyl group having 1 to 5 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl. Group, pentyl group, isopentyl group, neopentyl group and the like. Among these, a methyl group and an ethyl group are preferable because they are easily available industrially.

In general formula (aI-2), R ³⁵ and R ³⁶ are each independently preferably a linear or branched lower alkyl group having 1 to 5 carbon atoms. Among them, it is industrially preferable that both R ³⁵ and R ³⁶ are methyl groups. Specifically, a structural unit derived from 2- (1-adamantyl) -2-propyl (α-lower alkyl) acrylate is used. Can be mentioned.
In the general formula (aI-3), R ³⁷ is a tertiary alkyl group such as a tert-butyl group or a tert-amyl group, and a case where it is a tert-butyl group is industrially preferable.
The group —COOR ³⁷ may be bonded to the 3 or 4 position of the tetracyclododecanyl group shown in the formula, but the bonding position cannot be specified. Similarly, the carboxyl group residue of the (α-lower alkyl) acrylate structural unit may be bonded to the position 8 or 9 shown in the formula, but the bonding position cannot be specified.

..Structural unit (a2)
The structural unit (a2) is a structural unit derived from a mono (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group, and the ester side chain of the (α-lower alkyl) acrylate ester. Examples thereof include a structural unit in which a monocyclic group consisting of a lactone ring or a polycyclic alicyclic group having a lactone ring is bonded to the part.
At this time, the lactone ring indicates one ring containing an —O—C (O) — structure, and this is counted as the first ring. Therefore, here, in the case of only a lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
Specific examples of the lactone-containing monocyclic or polycyclic group in the structural unit (a2) include a monocyclic group obtained by removing one hydrogen atom from γ-butyrolactone, and one hydrogen atom from a lactone ring-containing polycycloalkane. And a polycyclic group except for.

  Specific examples of the structural unit (a2) include structural units represented by the following general formulas (aII-1), (aII-2), and (aII-3), respectively.

(In the formula, R ³¹ , R ³² and R ³³ are each independently a hydrogen atom or a linear or branched lower alkyl group.)

(In the formula, R ³¹ is a hydrogen atom or a linear or branched lower alkyl group.)

(In the formula, R ³¹ is a hydrogen atom or a linear or branched lower alkyl group.)

The lower alkyl group (α-lower alkyl group) as R ³¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, and n-butyl. Group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.

..Structural unit (a3)
The structural unit (a3) is a structural unit derived from a mono (α-lower alkyl) acrylate ester having a polycyclic alicyclic hydrocarbon group containing a hydroxyl group, and (α-lower alkyl) acrylate ester. A group in which at least one of the hydrogen atoms of the polycyclic alicyclic hydrocarbon group is substituted with a hydroxyl group is bonded to the ester side chain.
Examples of the polycyclic alicyclic hydrocarbon group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable, and an adamantyl group is particularly preferable.
The number of hydroxyl groups substituting for hydrogen atoms of the polycyclic alicyclic hydrocarbon group may be one or more, and the upper limit may be a substitutable number. Preferably it is 1-3.

  Specific examples of the structural unit (a3) include structural units represented by the following general formula (aIII).

(In the formula, R ³⁴ is a hydrogen atom or a linear or branched lower alkyl group. N is an integer of 1 to 3.)

The lower alkyl group (α-lower alkyl group) as R ³⁴ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, and n-butyl. Group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.
Further, n in the general formula (aIII) is preferably 1, and it is preferable that one hydroxyl group is bonded to the 3-position of the adamantyl group.

..Structural unit (a4)
The structural unit (a4) is a structural unit represented by the general formula (I).
In the said general formula (I), R < ¹ > is a hydrogen atom or a methyl group, and a methyl group is preferable industrially.
In the general formula (I), R ² is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms. Specific examples of the linear and branched hydrocarbon groups include methylene group, ethylene group, propane-1,3-diyl group, n-butane-1,4-diyl group, propane-1,2-diyl group. 2-methylpropane-1,3-diyl group, 2,2-dimethylpropane-1,3-diyl group and the like.
Specific examples of the cyclic hydrocarbon group include cycloalkane, bicycloalkane, tricycloalkane, teracycloalkane, benzene, naphthalene, anthracene, or one or more hydrogen atoms substituted with a linear or branched hydrocarbon group. Examples thereof include groups obtained by removing two hydrogen atoms from the above-described cyclic hydrocarbons. More specifically, a group obtained by removing two hydrogen atoms from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, or the like can be given. Among these, a group in which two hydrogen atoms are removed from adamantane, norbornane, and tetracyclododecane is industrially preferable, and a group in which two hydrogen atoms are removed from adamantane is particularly preferable.

In the general formula (I), R ³ and R ⁴ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, or an isopropyl group. Group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable. More preferably, one of R ³ and R ⁴ is a hydrogen atom and the other is a methyl group.
R ⁵ and R ⁶ are the same as R ³ and R ⁴ described above.

In the general formula (I), R ⁷ represents a linear, branched or cyclic alkylene group, alkylene ether group, cyclohexylene group or arylene group having 1 to 20 carbon atoms.
Specific examples of R ⁷ include methylene group, ethylene group, propane-1,3-diyl group, n-butane-1,4-diyl group, n-pentane-1,5-diyl group, n-hexane-1 , 6-diyl group, propane-1,2-diyl group, 2-methylpropane-1,3-diyl group, 2,2-dimethylpropane-1,3-diyl group, cyclohexane-1,4-diyl group, Two hydrogen atoms from a polycycloalkane such as 1,4-phenylene group, 1,5-naphthalene group, diethyl ether-2,2′-diyl group, adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, etc. Excluded groups and the like.
Among these, an ethylene group, a propane-1,3-diyl group, and an n-butane-1,4-diyl group are preferable.

  Specific examples of the structural unit (a4) include a structural unit (a4 ′) represented by the following general formula (II).

(Wherein R ⁸ is a hydrogen atom or a methyl group, and R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. R ¹³ represents a linear, branched or cyclic alkylene group, alkylene ether group, cyclohexylene group or arylene group having 1 to 20 carbon atoms.)
In the general formula (II), R ⁸ is the same as R ¹ described above. R ⁹ and R ¹⁰ are the same as R ³ and R ⁴ described above. R ¹¹ and R ¹² are the same as R ³ and R ⁴ . R ¹³ is the same as R ⁷ described above.

The structural unit (a4) has a structure in which precursor units obtained by substituting a hydrogen atom of a carboxyl group of (meth) acrylic acid with an —R ² —OH group are crosslinked. Here, the “precursor unit” is a monomer unit constituting the polymer and means a state before being crosslinked.
Examples of the precursor unit of the structural unit (a4) include the same units as the structural unit (a3). That is, the structural unit (a4) has a structure in which two structural units (a3) are cross-linked.
The two precursor units that are cross-linked to each other may be intramolecular cross-links that constitute the same copolymer, or may be inter-molecular cross-links that both constitute different copolymers. Intermolecular crosslinking is preferred.

The component (A1) having the structural unit (a4) is, for example, roughly synthesized in advance a polymer having a precursor unit of the structural unit (a4) (hereinafter, the polymer before the cross-linking reaction may be referred to as a precursor polymer). It can be formed by crosslinking reaction between precursor units using a crosslinking agent. The structural unit (a3) is used as the precursor unit, and the precursor polymer is a copolymer having the structural units (a1), (a2), and (a3), or the structural units (a1), (a2). , (A3), and a copolymer having (a5) described later are preferably used.
During the cross-linking reaction, all of the precursor units present in the precursor polymer may be cross-linked, or only a part may be cross-linked. When only some of the precursor units are cross-linked, in the component (A1) after cross-linking, in addition to the structural unit (a4) formed by cross-linking, a precursor unit that is not cross-linked is the structural unit (a3). Exists.

  Preferred examples of the chemically amplified photoresist polymer (A1) of the present invention are represented by the following general formulas (III-1), (III-2), (III-3), and (III-4), respectively. Or a polymer having a structural unit represented by each of the following general formulas (VI-1), (IV-2), (IV-3), and (IV-4). . In these, the structural units represented by the general formulas (III-1) and (VI-1) correspond to the structural unit (a1) and are represented by the general formulas (III-2) and (VI-2). The structural unit corresponds to the structural unit (a2), the structural units represented by the general formulas (III-3) and (VI-3) correspond to the structural unit (a3), and the general formula (III-4). And the structural unit represented by (VI-4) corresponds to the structural unit (a4).

(In the formula, R ¹⁴ , R ¹⁶ , R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom or a methyl group, and R ¹⁵ represents a linear or branched alkyl group having 1 to 6 carbon atoms.)
R ¹⁴ , R ¹⁶ , R ¹⁷ and R ¹⁸ are the same as R ¹ described above. R ¹⁵ is preferably a methyl group.

(In the formula, R ¹⁹ , R ²⁰ , R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group.)
R ¹⁹ , R ²⁰ , R ²¹ and R ²² are the same as R ¹ described above.

Hereinafter, a method for synthesizing the component (A1) will be described.
The component (A1) of the present invention is usually synthesized by [Method 1] or [Method 2] described in detail below, but the present invention is not limited to this method.
[Method 1] The (A1) component of the present invention forms a structural unit (a4) after polymerization and a (meth) acrylic acid ester compound that forms the structural units (a1), (a2), and (a3) after polymerization. A crosslinkable (meth) acrylic acid ester compound having two (meth) acrylic groups represented by the following general formula (VIII) and a polymerization initiator are dissolved in an organic solvent, and the temperature is set at an appropriate temperature for an appropriate time. It is synthesized by holding and polymerizing.

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, and R ³ , R ⁴ , R ⁵ , R ⁶ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁷ is a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, alkylene ether Group, a cyclohexylene group or an arylene group.)

The organic solvent used is preferably a solvent that can dissolve both the above-mentioned (meth) acrylic acid ester compound and the resulting polymer. For example, 1,4-dioxane, acetone, tetrahydrofuran, 2-butanone, 4-methyl Examples include 2-pentanone.
The polymerization initiator to be used is not particularly limited, and examples thereof include azo compounds such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), and organic peroxides such as benzoyl peroxide. Etc. are exemplified.
The polymerization conditions at this time can be appropriately set, but the polymerization temperature is usually preferably in the range of 50 to 150 ° C., and the polymerization time is preferably 1 hour to 10 hours, more preferably 4 hours. More than about.
Next, the polymer solution thus synthesized is diluted to a suitable solution viscosity with a good solvent such as tetrahydrofuran or 1,4-dioxane, and then injected into a large amount of poor solvent such as methanol or water. Precipitate. Then, the (A1) component of this invention can be obtained by filtering the deposit and fully drying.

[Method 2] In addition, the component (A1) of the present invention comprises, as an organic solvent, a (meth) acrylic acid ester compound and a polymerization initiator that form the structural units (a1), (a2), and (a3), respectively, after polymerization. A precursor polymer synthesized by dissolving and maintaining at a suitable temperature for a suitable time for polymerization is subjected to a crosslinking reaction using a crosslinkable polyvinyl ether compound that forms the structural unit (a4) after crosslinking. Can be synthesized.
The organic solvent used for the synthesis of the precursor polymer is preferably a solvent capable of dissolving both the above-mentioned (meth) acrylic acid ester compound and the obtained polymer, such as 1,4-dioxane, acetone, tetrahydrofuran, 2 -Butanone, 4-methyl-2-pentanone and the like are exemplified.
The polymerization initiator used is not particularly limited. For example, azo compounds such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), and organic peroxidation such as benzoyl peroxide. Examples are things.
The polymerization conditions at this time can be set as appropriate, but the polymerization temperature is preferably in the range of 50 to 150 ° C., and the reaction time is preferably 1 to 10 hours, more preferably 4 More than about hours.

The precursor polymer solution thus obtained, or a crosslinking agent that separates the precursor polymer from the precursor polymer solution and then forms the structural unit (a4) after crosslinking in the precursor polymer solution dissolved in an appropriate solvent. And (A1) component of this invention are synthesize | combined by adding an acid catalyst and hold | maintaining the temperature for a suitable time at a suitable temperature, and performing a crosslinking reaction.
For separation of the precursor polymer, the precursor polymer solution is diluted to a suitable solution viscosity with a good solvent such as tetrahydrofuran or 1,4-dioxane, and then poured into a large amount of poor solvent such as methanol or water for precipitation. . Thereafter, the precipitate is filtered and sufficiently dried.
The solvent for dissolving the precursor polymer is preferably a solvent capable of dissolving the aforementioned precursor polymer, such as 1,4-dioxane, acetone, tetrahydrofuran, 2-butanone, 4-methyl-2-pentanone, and ethyl acetate. Illustrated.

The cross-linking agent may be one that can form a cross-linked moiety in the structural unit (a4) represented by the general formula (I), and is not particularly limited. For example, a cross-linkable polyvinyl ether having two cross-linkable vinyl ether groups. Compounds can be used. Specific examples include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether. And tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, cyclohexane dimethanol divinyl ether, and the like.
Although it does not specifically limit as an acid catalyst used, For example, p-toluenesulfonic acid, pyridinium-p-toluenesulfonate, a sulfuric acid etc. are illustrated.

The amount of the crosslinking agent used is determined by the amount for obtaining a preferred proportion of the structural unit (a4) when the component (A1) is used in the positive resist composition, and the amount of the acid catalyst used is the crosslinkable polyvinyl ether compound to be used. 0.001-50 mol% is preferable with respect to this.
The crosslinking reaction conditions can be appropriately set, but the reaction temperature is usually preferably in the range of 0 to 100 ° C., and the reaction time is preferably 15 minutes to 10 hours, more preferably 30 minutes or more. .
After completion of the crosslinking reaction, a basic compound such as triethylamine, tributylamine, or pyridine is added to the reaction solution to stop the reaction, and then this solution is mixed with a good solvent such as tetrahydrofuran or 1,4-dioxane. After diluting to a viscosity, it is poured into a large amount of poor solvent such as methanol or water and precipitated. Then, the (A1) component of this invention can be obtained by filtering the deposit and fully drying.
After the synthesis of the precursor polymer and / or after the cross-linking reaction, the degree of dispersion may be adjusted by performing a known purification step, if necessary.

When the component (A1) is synthesized by the [Method 1], in the component (A1) after polymerization, the structural unit (a1) is preferably 20 to 70 mol%, more preferably 30 to 60 mol%. is there. By setting it to the lower limit value or more, a good fine pattern can be obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.
The structural unit (a2) is contained in an amount of 20 to 60 mol%, preferably 20 to 50 mol%. By setting the lower limit value or more, a good fine pattern can be obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.
The structural unit (a3) is contained in an amount of 0 to 40 mol%, preferably 0.15 to 6 mol%. By setting it to the upper limit value or less, a good fine pattern can be obtained when used in a positive resist composition.
It is preferable that a structural unit (a4) is 5-40 mol%, More preferably, it is 10-30 mol%. By setting the lower limit value or more, it is possible to introduce a preferred proportion of the (a4) structural unit as a resist. By setting the upper limit value or less, an excessive crosslinking reaction such as gelation can be prevented and a positive resist composition can be obtained. When used, a good fine pattern can be obtained.

  When the component (A1) is synthesized by the [Method 2], in the precursor polymer before being crosslinked, the constituent unit (a1) is 20 to 70 with respect to the total of all constituent units constituting the precursor polymer. It is preferable that it is mol%, More preferably, it is 30-60 mol%. By setting it to the lower limit value or more, it is possible to obtain a good fine pattern when used in a positive resist composition, and to set the upper limit value or less to balance with other structural units.

  The structural unit (a2) is preferably contained in an amount of 20 to 60 mol%, preferably 20 to 50 mol%, based on the total of all the structural units constituting the precursor polymer. By setting it to the lower limit value or more, a good fine pattern can be obtained when used in a positive resist composition, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

The proportion of the precursor unit of the structural unit (a4) in the precursor polymer is preferably 5 to 40 mol%, more preferably 10 to 30 mol%. By setting the lower limit value or more, it is possible to introduce a preferred proportion of the (a4) structural unit as a resist. By setting the upper limit value or less, an excessive crosslinking reaction such as gelation can be prevented and a positive resist composition can be obtained. When used, a good fine pattern can be obtained.
In the crosslinking reaction, 0 to 98 mol%, more preferably 3 to 15 mol% of the precursor units in the precursor polymer are not crosslinked, and the structural unit (a3) is contained in the component (A1) after crosslinking. ) Is preferably present. That is, the structural unit (a3) is contained in the component (A1) in an amount of 0 to 40 mol%, preferably 0.15 to 6 mol%. By setting it to the upper limit value or less, a good fine pattern can be obtained when used in a positive resist composition.

..Structural unit (a5)
The component (A1) may further contain another structural unit (a5).
The structural unit (a5) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1) to (a4). That is, if it does not have an acid dissociable, dissolution inhibiting group, a lactone-containing monocyclic or polycyclic group, a polycyclic alicyclic hydrocarbon group containing a hydroxyl group, and a structure represented by the general formula (I) Good. For example, a structural unit containing a polycyclic alicyclic hydrocarbon group and derived from a (meth) acrylic acid ester is preferable. When such a structural unit is used, when used for a positive resist composition, a solution from an isolated pattern to a semi-dense pattern (a line and space pattern having a space width of 1.2 to 2 with respect to a line width of 1) is obtained. It is excellent in image properties and is preferable.

Examples of such polycyclic alicyclic hydrocarbon groups include those exemplified in the structural units (a1) and (a3), and are conventionally known as ArF positive resist materials. It can be used by appropriately selecting from a large number.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, and a tetracyclododecanyl group is preferable in terms of industrial availability.

  Examples of these structural units (a5) include compounds represented by the following general formulas (V) to (VII).

(In the formula, R is a hydrogen atom or a linear or branched lower alkyl group.)

(In the formula, R is a hydrogen atom or a linear or branched lower alkyl group.)

(In the formula, R is a hydrogen atom or a linear or branched lower alkyl group.)

The lower alkyl group (α-lower alkyl group) as R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or an n-butyl group. , Isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.
The structural unit (a5) is not an essential component of the component (A1). However, when the structural unit (a5) is contained in the component (A1), the structural unit (a5) is added to the total of all structural units of the component (A1). When contained in an amount of 1 to 30 mol%, preferably 10 to 20 mol%, a good improvement effect can be obtained in the resolution of a semi-dense pattern from an isolated pattern when used in a positive resist composition. preferable.

The mass average molecular weight Mw of the precursor polymer before crosslinking of the component (A1) is a polystyrene standard by gel permeation chromatography (hereinafter the same), preferably 1000 to 20000, more preferably 1000 to 10000, More preferably, it is 2000-7000. By setting the mass average molecular weight below the upper limit and above the lower limit of the above range, a good fine pattern can be obtained when the (A1) component after crosslinking is used in a positive resist composition.
Further, the dispersity in the precursor polymer, that is, the ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) is preferably in the range of 1.2 to 3.0, and preferably 1.4 to 2.5. Furthermore, the range of 1.4 to 2.0 is preferable. By setting the dispersity below the upper limit and above the lower limit of the above range, a good fine pattern can be obtained when the (A1) component after crosslinking is used in a positive resist composition.

Moreover, 2000-30000 are preferable, as for the mass mean molecular weight Mw of the (A1) component after bridge | crosslinking, More preferably, it is 5000-20000, More preferably, it is 7000-18000. By setting the mass average molecular weight below the upper limit and above the lower limit of the above range, a good fine pattern can be obtained when the component (A1) is used in a positive resist composition.
The degree of dispersion (Mw / Mn) in the component (A1) after crosslinking is preferably in the range of 1.5 to 4.0, more preferably in the range of 1.7 to 3.5, and even more preferably in the range of 1.9 to 3.0. preferable. By making the degree of dispersion not more than the upper limit of the above range, a good fine pattern can be obtained when the component (A1) is used in a positive resist composition.

[Positive resist composition]
The chemically amplified photoresist polymer (A1) of the present invention is useful as a resin component of a positive resist composition.
The positive resist composition using the component (A1) contains a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) which generates an acid upon exposure. ) Component contains the component (A1) of the present invention. The resin component (A) may contain an appropriate resin other than the component (A1) as long as the effects of the present invention are not impaired, but 100% by mass of the component (A) is the component (A1). It is preferable.

Acid generator component (B) (hereinafter sometimes referred to as component (B))
The component (B) can be used without particular limitation from known acid generators used in conventional chemically amplified resist compositions.
Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, There are various known diazomethane acid generators such as diazomethane nitrobenzyl sulfonates, imino sulfonate acid generators and disulfone acid generators.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethane. Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethane Sulfonate, its heptafluoropropane sulphonate or its Nafluorobutane sulfonate, trifluoromethane sulfonate of monophenyldimethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of diphenyl monomethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, (4- Trifluoromethanesulfonate of methylphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of (4-methoxyphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, tri (4 -Tert-bu Le) trifluoromethanesulfonate triphenylsulfonium, its like heptafluoropropane sulfonate or nonafluorobutane sulfonates.

  Specific examples of the oxime sulfonate acid generator include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino)- Phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methylsulfonyloxyimino) -p-bromophenylacetonitrile and the like can be mentioned. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

  In the present invention, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. If the amount is less than the above range, pattern formation may not be sufficiently performed, and if the amount exceeds the above range, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

・ Nitrogen-containing organic compounds (D)
In the positive resist composition according to the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as the component (D)) is further added as an optional component in order to improve the resist pattern shape, the stability over time. Can be blended.
Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred. .
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine and the like can be mentioned, and tertiary alkanolamines such as triethanolamine are particularly preferable.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

-Component (E) In addition, for the purpose of preventing sensitivity deterioration due to the blending with the component (D) and improving the resist pattern shape, retention stability, etc., an organic carboxylic acid or phosphorus oxo is further added as an optional component. An acid or a derivative thereof (E) (hereinafter referred to as “component (E)”) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

Organic solvent The positive resist composition according to the present invention can be produced by dissolving the material in an organic solvent.
Any organic solvent may be used as long as it can dissolve each component to be used to form a uniform solution, and one or two kinds of conventionally known solvents for chemically amplified resists can be used. These can be appropriately selected and used.
For example, ketones such as γ-butyrolactone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol Or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and other polyhydric alcohols and derivatives thereof, cyclic ethers such as dioxane, methyl lactate, lactic acid Ethyl (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxy Methyl propionate, esters such as ethyl ethoxypropionate can be exemplified.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 2: 8 to 8: 2, more preferably 3: 7 to 7: 3.
In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
Although the amount of the organic solvent used is not particularly limited, it is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 to 20 mass. %, Preferably 5-15% by mass.

Other optional components The positive resist composition according to the present invention may further contain miscible additives, for example, an additional resin for improving the performance of the resist film, and a surface activity for improving coating properties. An agent, a dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

-Resist pattern formation method The method of forming a resist pattern using the positive photoresist composition concerning this invention can be performed as follows, for example.
That is, first, the positive resist composition is applied onto a substrate such as a silicon wafer with a spinner and prebaked for 40 to 120 seconds, preferably 60 to 90 seconds under a temperature condition of 80 to 150 ° C. After selectively exposing ArF excimer laser light through a desired mask pattern using, for example, an ArF exposure apparatus or the like, PEB (post-exposure heating) is performed for 40 to 120 seconds at a temperature of 80 to 150 ° C., preferably Apply for 60-90 seconds. Subsequently, this is developed using an alkaline developer, for example, an aqueous 0.1 to 10% by mass tetramethylammonium hydroxide solution. In this way, a resist pattern faithful to the mask pattern can be obtained.
An organic or inorganic antireflection film can be provided between the substrate and the coating layer of the resist composition.

The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. In particular, the photoresist composition according to the present invention is effective for an ArF excimer laser.

In the positive resist composition according to the present invention, the component (A) has an acid dissociable, dissolution inhibiting group, and the acid dissociable dissolution inhibiting group is dissociated by the action of an acid generated from the component (B), Alkali solubility increases.
More specifically, when the acid generated from the component (B) by exposure acts on the component (A), the acid dissociable, dissolution inhibiting group in the component (A) is dissociated, whereby the entire positive resist is alkali-insoluble to alkaline. It becomes soluble. Therefore, when a positive resist is exposed through a mask pattern in the formation of a resist pattern, or when PEB is performed in addition to exposure, the exposed portion turns alkali-soluble while the unexposed portion remains alkali-insoluble. Therefore, a positive resist pattern can be formed by alkali development.

In particular, by incorporating the component (A1) of the present invention into a positive resist composition, a resist pattern with high resolution and low LER can be formed. This is because the component (A1) has the crosslinked structural unit (a4), so that the solubility of the component (A1) itself in an alkaline developer is reduced, and the crosslinking site of the structural unit (a4) Since the acid-dissociable group is formed in the exposed portion, the crosslinking site is cleaved in the exposed portion, and as a result, the high solubility in the alkali developer is considered to contribute greatly. Thus, it is considered that the solubility greatly changes between the exposed area and the unexposed area, thereby increasing the contrast and improving the limit resolution and reducing the LER.
In particular, when the structural unit (a4) is intermolecularly bonded, the molecular weight of the resin component is greatly reduced due to cleavage at the cross-linked site of the structural unit (a4). It is thought that sex changes greatly.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

(Synthesis Example 1)
A polymer (A1-1) represented by the following general formula was synthesized.

(1) Synthesis of Precursor Polymer Into a four-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, 2500 g of tetrahydrofuran, 320 g of 2-methyl-2-adamantyl methacrylate, 230 g of γ-butyrolactone methacrylate and 3- After putting 160 g of hydroxy-1-adamantyl methacrylate and replacing with nitrogen, the temperature was raised to 70 ° C. with stirring. While maintaining the temperature, a polymerization initiator solution in which 80 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 120 g of tetrahydrofuran was dropped over 15 minutes. After completion of the dropwise addition, stirring was continued for 5 hours while maintaining the temperature, and then the mixture was cooled to 25 ° C. to complete the polymerization.
Thereafter, the obtained polymerization solution was dropped into a large amount of methanol / water mixed solution to obtain a precipitate. The precipitate was filtered, washed and dried to obtain a white solid random copolymer (precursor polymer).
(2) Identification of the white solid obtained in (1) and mass average molecular weight determined in terms of polystyrene by gel permeation chromatography (GPC); 5,600, dispersity 1.9
Monomer composition ratio by isotope carbon nuclear magnetic resonance ( ¹³ C-NMR) analysis; 2-methyl-2-adamantyl methacrylate / γ-butyrolactone methacrylate / 3-hydroxy-1-adamantyl methacrylate = 39/41/20 mol %

(3) Crosslinking 140 g of the obtained white solid, 700 g of tetrahydrofuran, and 20 mg of p-toluenesulfonic acid monohydrate were placed in a four-necked flask equipped with a nitrogen blowing tube, a refluxer, a dropping funnel and a thermometer, and stirred. The temperature was raised to 50 ° C. While maintaining the temperature, a solution prepared by dissolving 6 g of 1,4-butanediol divinyl ether in 1 g of tetrahydrofuran was dropped. After completion of dropping, the mixture was stirred for 3 hours while maintaining the temperature, and then cooled to 25 ° C. Thereafter, triethylamine was added to stop the reaction.
The obtained reaction solution was dropped into a large amount of water to obtain a precipitate. This precipitate was filtered, washed and dried to obtain a white solid random copolymer (polymer (A1-1)).
(4) Identification of the white solid obtained in (3) / Mass average molecular weight determined in terms of polystyrene by gel permeation chromatography (GPC); 10,700, dispersity 2.9
-Crosslinking rate of hydroxyl group of 3-hydroxy-1-adamantyl methacrylate site determined by isotope hydrogen nuclear magnetic resonance ( ¹ H-NMR) analysis: 4%

(Synthesis Example 2)
A polymer (A1-2) represented by the following general formula was synthesized.

(1) Synthesis of Precursor Polymer A 4-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer was attached with 520 g of methyl ethyl ketone, 20 g of 1-cyclohexyl methacrylate, 20 g of γ-butyrolactone methacrylate and 3-hydroxy-1-adamantyl. After adding 60 g of methacrylate and replacing with nitrogen, the temperature was raised to 85 ° C. with stirring. While maintaining the temperature, 250 g of 1-cyclohexyl methacrylate, 210 g of γ-butyrolactone methacrylate, 150 g of 3-hydroxy-1-adamantyl methacrylate and 80 g of dimethyl-2,2′-azobisisobutyrate were dissolved in 1250 g of methyl ethyl ketone. The solution was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was stirred for 3 hours while maintaining the temperature, and then cooled to 25 ° C. to complete the polymerization.
Thereafter, the obtained polymerization solution was dropped into a large amount of methanol to obtain a precipitate. The precipitate was filtered, washed and dried to obtain a white solid random copolymer (precursor polymer).
(2) Identification of the white solid obtained in (1) and mass average molecular weight determined in terms of polystyrene by gel permeation chromatography (GPC): 5,000, dispersity 1.7
Monomer composition ratio by isotope carbon nuclear magnetic resonance ( ¹³ C-NMR) analysis: 1-cyclohexyl methacrylate / γ-butyrolactone methacrylate / 3-hydroxy-1-adamantyl methacrylate = 35/43/22 mol%

(3) Crosslinking A white solid 130 g, tetrahydrofuran 650 g, and p-toluenesulfonic acid monohydrate 20 mg were put into a 4-neck flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, and stirred. The temperature was raised to 50 ° C. While maintaining the temperature, a solution prepared by dissolving 8 g of 1,4-butanediol divinyl ether in 1 g of tetrahydrofuran was dropped. After completion of dropping, the mixture was stirred for 3 hours while maintaining the temperature, and then cooled to 25 ° C. Thereafter, triethylamine was added to stop the reaction.
The obtained reaction solution was dropped into a large amount of water to obtain a precipitate. This precipitate was filtered, washed and dried to obtain a white solid random copolymer (polymer (A1-2)).
(4) Identification of the white solid obtained in (3) and mass average molecular weight determined in terms of polystyrene by gel permeation chromatography (GPC); 9,400, dispersity 2.6
-Crosslinking rate of hydroxyl group of 3-hydroxy-1-adamantyl methacrylate site determined by isotope hydrogen nuclear magnetic resonance ( ¹ H-NMR) analysis: 4%

(Resist Preparation Example 1)
Using the polymer (A1-1) obtained in (3) of Synthesis Example 1, a positive resist composition was prepared with the following composition.
(A) 100 parts by mass of the polymer (A1-1) as a component,
(B) 4-methylphenyldiphenylsulfonium nonafluorobutanesulfonate 3.0 parts by mass as component (D) 0.35 parts by mass of triethanolamine as component (A) to (D) are changed to PGMEA: EL = 6: 4 A positive resist composition having a solid content concentration of 10% by mass was prepared by dissolving in an organic solvent.

(Comparative resist preparation example 1)
In Resist Preparation Example 1, in place of the polymer (A1-1), positive polarity was obtained in the same manner as in Resist Preparation Example 1, except that 100 parts by mass of the precursor polymer obtained in (1) of Synthesis Example 1 was used. A mold resist composition was prepared.

(Comparative resist preparation example 2)
In Synthesis Example 1 (1), by changing the synthesis conditions, mass average molecular weight: 10,000, degree of dispersion 1.9, monomer composition ratio; 2-methyl-2-adamantyl methacrylate / γ-butyrolactone methacrylate A copolymer having no crosslinkable group was synthesized in which / 3-hydroxy-1-adamantyl methacrylate = 39/41/20 mol%.
A positive resist composition was prepared in the same manner as in Resist Preparation Example 1, except that the obtained copolymer was used in place of the polymer (A1-1).

(Evaluation methods)
A resist pattern was formed using the positive resist compositions obtained in Resist Preparation Example 1 and Comparative Resist Preparation Examples 1 and 2.
First, an organic antireflection film composition “ARC-29A” (trade name, manufactured by Brewer Science Co., Ltd.) was applied on an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds. By drying, an organic antireflection film having a thickness of 77 nm was formed.
Next, the positive resist composition was applied on the antireflection film using a spinner, pre-baked (PAB) at 120 ° C. for 90 seconds on a hot plate, and dried to form a resist layer having a thickness of 300 nm. .
Next, an ArF excimer laser (193 nm) is selectively passed through a mask pattern (halftone) using an ArF exposure apparatus NSR-S302 (manufactured by Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 ring zone). Irradiated.
Then, PEB treatment is performed at 120 ° C. for 90 seconds, and further paddle development is performed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, followed by washing with water for 20 seconds and drying to form a resist pattern. did.
In Comparative Resist Preparation Example 2, the prebake temperature was changed to 130 ° C. and the PEB temperature was changed to 130 ° C.
In this way, a 1: 1 130 nm line and space pattern was formed.

The following items were evaluated for the resist pattern formed above.
<Sensitivity>
The exposure time at which a 130 nm line and space was formed at 1: 1 was measured as sensitivity (EOP) in mJ / cm ² (energy amount).
<LER>
For a 1: 1 line and space pattern with a line width of 130 nm, 3σ, which is a measure indicating LER, was determined. A side length SEM (trade name “S-9220” manufactured by Hitachi, Ltd.) was used to measure the width of the resist pattern of the sample at 32 locations, which is three times the standard deviation (σ) calculated from the result (3σ). . This 3σ means that the smaller the value, the smaller the roughness and the uniform width resist pattern was obtained.

From the above results, it was found that Example 1 had high resolution and reduced LER.

Claims (3)

The following general formula (I)

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, and R ³ , R ⁴ , R ⁵ , R ⁶ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁷ is a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, alkylene ether Group, a cyclohexylene group or an arylene group.)
A polymer for a chemically amplified photoresist, comprising a structural unit (a4) represented by the formula: As the structural unit (a4), the following general formula (II)

(In the formula, R ⁸ is a hydrogen atom or a methyl group, and R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. R ¹³ represents a linear, branched or cyclic alkylene group, alkylene ether group, cyclohexylene group or arylene group having 1 to 20 carbon atoms.)
The polymer for chemically amplified photoresists according to claim 1, comprising a structural unit (a4 ′) represented by: Polymers having structural units respectively represented by the following general formulas (III-1), (III-2), (III-3), and (III-4), or the following general formulas (VI-1), ( The polymer amplifying photoresist weight according to claim 1 or 2, which is a polymer having structural units represented by IV-2), (IV-3), and (IV-4), respectively. Coalescence.

(In the formula, R ¹⁴ , R ¹⁶ , R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom or a methyl group, and R ¹⁵ represents a linear or branched alkyl group having 1 to 6 carbon atoms.)

(In the formula, R ¹⁹ , R ²⁰ , R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group.)