JP2013231992A - Positive resist composition, method of forming resist pattern, and polymeric compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polymeric compound, a novel positive resist composition, and a method of forming a resist pattern using the positive resist composition.SOLUTION: A positive resist composition comprises a base component (A) which exhibits increased solubility in an alkali developing solution under action of an acid, and an acid generator component (B) which generates an acid upon exposure to radiation. The base component (A) comprises a polymeric compound (A1). The polymeric compound (A1) has: a structural unit (a0) represented by the specified general formula (a0-1); a structural unit (a2) derived from an acrylate ester which has a lactone-containing cyclic group; and a structural unit (a1) which does not correspond with the structural unit (a0) and is derived from an acrylate ester which has an acid dissociable, dissolution inhibiting group.

Description

  The present invention relates to a novel polymer compound and a positive resist composition, and a resist pattern forming method using the positive resist composition.

In lithography technology, for example, a resist film made of a resist material is formed on a substrate, and the resist film is selectively exposed to light such as light or an electron beam through a mask on which a predetermined pattern is formed. And a development process is performed to form a resist pattern having a predetermined shape on the resist film. There are two types of resist materials: a positive type in which the solubility of the exposed portion in the developer is increased and a negative type in which the solubility of the exposed portion in the developer is decreased.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has been rapidly progressing due to advances in lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but at present, mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. In addition, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.
Resist materials are required to have high lithography characteristics such as sensitivity to such an exposure light source and resolution capable of reproducing a pattern with fine dimensions. As a resist material that satisfies such requirements, a chemically amplified resist containing a base resin whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. For example, as a positive chemically amplified resist, a resist containing an acid generator component and a resin component having an acid dissociable, dissolution inhibiting group that is dissociated by the action of an acid generated from the acid generator is generally used. It has been.

Currently, as a resist base resin used in ArF excimer laser lithography and the like, a resin (acrylic resin) having a structural unit derived from (meth) acrylic acid ester in its main chain because of its excellent transparency near 193 nm Etc. are generally used (see, for example, Patent Document 1). Here, “(meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. “(Meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position. “(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.
In the case of the positive type, as the acrylic resin, a resin having a structural unit derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group is used (see Patent Documents 1 and 2).
Currently, as a base resin for a chemically amplified resist, a resin containing a plurality of structural units is usually used in order to improve lithography properties and the like. For example, in the case of the positive type, those containing a structural unit having a polar group such as a hydroxyl group, a structural unit having a lactone structure, etc. in addition to the above-described structural unit having an acid dissociable, dissolution inhibiting group are usually used. .

JP 2003-241385 A JP 2006-096965 A

In recent years, the miniaturization of resist patterns has further progressed, and as the demand for high resolution further increases, the resist composition is also required to improve various lithography properties. One of such characteristics is line width roughness (hereinafter sometimes abbreviated as “LWR”). LWR is a phenomenon in which the line width of a line pattern becomes non-uniform when a resist pattern is formed using a resist composition, and the improvement becomes more important as the pattern becomes finer.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel polymer compound, a positive resist composition, and a resist pattern forming method using the positive resist composition. .

In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention contains a base component (A) whose solubility in an alkaline developer is increased by the action of an acid, and an acid generator component (B) that generates an acid upon irradiation with radiation. A positive resist composition comprising:
The base material component (A) contains a polymer compound (A1),
The polymer compound (A1) is a structural unit (a0) represented by the following general formula (a0-1), a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, A structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, not corresponding to the structural unit (a0),
A positive type wherein the molar ratio between the structural unit (a0) and the structural unit (a1) is in the range of the structural unit (a0): the structural unit (a1) = 1: 9 to 4: 6. It is a resist composition.

［式（ａ０−１）中、Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^５はアルキル基であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン原子、ハロゲン化アルキル基からなる群から選択される置換基であり、ｅは０〜５の整数である。］

[In Formula (a0-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, R ⁵ is an alkyl group, and R ⁶ is an alkyl group. And a substituent selected from the group consisting of an alkoxy group, a halogen atom, and a halogenated alkyl group, and e is an integer of 0 to 5. ]

According to a second aspect of the present invention, there is provided a step of forming a resist film on a support using the positive resist composition of the first aspect, a step of exposing the resist film, and an alkali development of the resist film. And a resist pattern forming method including a step of forming a resist pattern.
The third aspect of the present invention is the structural unit (a0) represented by the following general formula (a0-1), the structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, A structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, not corresponding to the structural unit (a0),
A polymer having a molar ratio of the structural unit (a0) to the structural unit (a1) in the range of the structural unit (a0): the structural unit (a1) = 1: 9 to 4: 6. A compound.

［式（ａ０−１）中、Ｒ^１は水素原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基であり、Ｒ^５はアルキル基であり、Ｒ^６はアルキル基、アルコキシ基、ハロゲン原子、ハロゲン化アルキル基からなる群から選択される置換基であり、ｅは０〜５の整数である。］

[In Formula (a0-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, R ⁵ is an alkyl group, and R ⁶ is an alkyl group. And a substituent selected from the group consisting of an alkoxy group, a halogen atom, and a halogenated alkyl group, and e is an integer of 0 to 5. ]

In the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting a polymer compound (polymer, copolymer).
The “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
“Exposure” is a concept that includes general irradiation of radiation.

  According to the present invention, it is possible to provide a novel polymer compound and positive resist composition, and a resist pattern forming method using the positive resist composition.

≪Polymer compound≫
The polymer compound of the present invention (hereinafter referred to as polymer compound (A1)) has the structural unit (a0) represented by the general formula (a0-1).

<Structural unit (a0)>
In the formula (a0-1), as the lower alkyl group for R ¹ , specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl And a lower linear or branched alkyl group such as a neopentyl group.
Examples of the halogenated lower alkyl group for R ¹ include groups in which some or all of the hydrogen atoms in the lower alkyl group have been substituted with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
R ¹ is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, and most preferably a hydrogen atom or a methyl group from the viewpoint of industrial availability.

As the alkyl group for R ^5, a linear or branched alkyl group is preferable, and the number of carbon atoms is preferably 1 to 5. Specific examples thereof include the same lower alkyl groups as those described above for R ¹ , and a methyl group or an ethyl group is particularly preferable.

Examples of the alkyl group of R ^{6 and} the alkyl group in the alkoxy group include the same as the lower alkyl group of R ¹ .
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
Examples of the halogenated alkyl group include the same halogenated lower alkyl groups as those described above for R ¹ .
e is an integer of 0 to 5, an integer of 0 to 2 is preferable, and 0 is most preferable.

  The structural unit (a0) contained in the polymer compound (A1) may be one type or two or more types.

The polymer compound (A1) may be a polymer composed only of the structural unit (a0), or may be a copolymer containing another structural unit.
In the polymer compound (A1), the proportion of the structural unit (a0) is the total proportion of the structural unit (a0) and the structural unit (a1) described later (in the case where the structural unit (a1) is not included). The amount of the unit (a0)) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, more preferably from 25 to 50, based on all the structural units constituting the polymer compound (A1). Most preferred is an amount of mol%. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.
In particular, since the positive resist composition containing the polymer compound (A1) is excellent in lithography properties such that a resist pattern having a small LWR can be formed, the proportion of the structural unit (a0) is high. ) Is preferably 1 mol% or more, more preferably 5 mol% or more with respect to all the structural units constituting.

When the polymer compound (A1) of the present invention is a copolymer containing a structural unit other than the structural unit (a0), the structural unit other than the structural unit (a0) is not particularly limited, Until now, it may be an arbitrary structural unit used for the base resin for chemically amplified resist. Specific examples include the following structural units (a1) to (a4).
Of these, the polymer compound (A1) preferably further has a structural unit (a2) in addition to the structural unit (a0).
The polymer compound (A1) preferably further has a structural unit (a3) in addition to the structural unit (a0) or in addition to the structural unit (a0) and the structural unit (a2).
The polymer compound (A1) is added to the structural unit (a0), to the structural units (a0) and (a2), or to the structural units (a0), (a2) and (a3). Furthermore, it is preferable to have a structural unit (a1).

<Structural unit (a1)>
The structural unit (a1) is a structural unit derived from an acrylate ester not containing the structural unit (a0) and containing an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire polymer compound (A1) insoluble in an alkali developer before dissociation, and is dissociated by an acid to cause this high It increases the solubility of the molecular compound (A1) in the alkaline developer, and what has been proposed as an acid dissociable, dissolution inhibiting group for a base resin for a chemically amplified resist can be used. . In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group in (meth) acrylic acid or the like; an acetal-type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group is widely known. . The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

Here, the “tertiary alkyl ester” is an ester formed by replacing a hydrogen atom of a carboxy group with a chain or cyclic alkyl group, and the carbonyloxy group (—C (O)). A structure in which the tertiary carbon atom of the chain or cyclic alkyl group is bonded to the terminal oxygen atom of -O-). In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The chain or cyclic alkyl group may have a substituent.
Hereinafter, a group that is acid dissociable by constituting a carboxy group and a tertiary alkyl ester is referred to as a “tertiary alkyl ester type acid dissociable, dissolution inhibiting group” for convenience.
Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.

Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
“Aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-pentyl group, and a tert-heptyl group. .

The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Examples of the aliphatic cyclic group include monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. And groups obtained by removing one or more hydrogen atoms from a polycycloalkane. More specifically, monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane are exemplified. .

  Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group. Specifically, 2-methyl-2 -Adamantyl group, 2-ethyl-2-adamantyl group, etc. are mentioned. Alternatively, in the structural units represented by the following general formulas (a1 ″ -1) to (a1 ″ -6), an adamantyl group such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—) An aliphatic cyclic group such as a cyclohexyl group, a cyclopentyl group, a norbornyl group, a tricyclodecanyl group, or a tetracyclododecanyl group, and a branched alkylene group having a tertiary carbon atom bonded thereto. Groups.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｒ^１５、Ｒ^１６はアルキル基（直鎖状、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である）を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹⁵ and R ^{16 each} represents an alkyl group (which may be linear or branched, and preferably has 1 to 5 carbon atoms. Is). ]

  In the general formulas (a1 ″ -1) to (a1 ″ -6), the lower alkyl group or halogenated lower alkyl group of R is a lower alkyl group or halogenated lower alkyl which may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.

The “acetal acid dissociable, dissolution inhibiting group” is generally bonded to an oxygen atom by substituting a hydrogen atom at the terminal of an alkali-soluble group such as a carboxy group or a hydroxyl group. When an acid is generated by exposure, the acid acts to break the bond between the acetal acid dissociable, dissolution inhibiting group and the oxygen atom to which the acetal acid dissociable, dissolution inhibiting group is bonded.
Examples of the acetal type acid dissociable, dissolution inhibiting group include a group represented by the following general formula (p1).

［式中、Ｒ^１’，Ｒ^２’はそれぞれ独立して水素原子または低級アルキル基を表し、ｎは０〜３の整数を表し、Ｙは低級アルキル基または脂肪族環式基を表す。］

[Wherein, R ¹ ′ and R ² ′ each independently represents a hydrogen atom or a lower alkyl group, n represents an integer of 0 to 3, and Y represents a lower alkyl group or an aliphatic cyclic group. ]

In the above formula, n is preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.
Examples of the lower alkyl group for R ¹ ′ and R ² ′ include the same lower alkyl groups as those described above for R. A methyl group or an ethyl group is preferable, and a methyl group is most preferable.
In the present invention, it is preferable that at least one of R ¹ ′ and R ² ′ is a hydrogen atom. That is, the acid dissociable, dissolution inhibiting group (p1) is preferably a group represented by the following general formula (p1-1).

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

[Wherein R ¹ ′, n and Y are the same as described above. ]

Examples of the lower alkyl group for Y include the same lower alkyl groups as those described above for R.
The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in a number of conventional ArF resists. For example, the above “aliphatic ring” Examples thereof are the same as those in the formula group.

  Examples of the acetal type acid dissociable, dissolution inhibiting group also include a group represented by the following general formula (p2).

［式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐鎖状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐鎖状または環状のアルキル基である。または、Ｒ^１７およびＲ^１９がそれぞれ独立に直鎖状または分岐鎖状のアルキレン基であって、Ｒ^１７の末端とＲ^１９の末端とが結合して環を形成していてもよい。］

[Wherein, R ¹⁷ and R ¹⁸ each independently represent a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ represents a linear, branched or cyclic alkyl group. Alternatively, R ¹⁷ and R ¹⁹ may be each independently a linear or branched alkylene group, and the end of R ^{17 and} the end of R ¹⁹ may be bonded to form a ring. ]

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include a group excluding a hydrogen atom. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
In the above formula, R ¹⁷ and R ¹⁹ are each independently a linear or branched alkylene group (preferably an alkylene group having 1 to 5 carbon atoms), and the end of R ^{19 and} the end of R ¹⁷ And may be combined.
In this case, a cyclic group is formed by R ¹⁷ , R ¹⁹ , the oxygen atom to which R ¹⁹ is bonded, and the carbon atom to which the oxygen atom and R ¹⁷ are bonded. The cyclic group is preferably a 4- to 7-membered ring, and more preferably a 4- to 6-membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

  As the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-0-1) and structural units represented by the following general formula (a1-0-2): Is preferably used.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^１は酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; and X ¹ represents an acid dissociable, dissolution inhibiting group. ]

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an alkylene group or an aliphatic cyclic group. ]

In general formula (a1-0-1), the lower alkyl group or halogenated lower alkyl group for R is the same as the lower alkyl group or halogenated lower alkyl group that may be bonded to the α-position of the acrylate ester. .
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include the above-described tertiary alkyl ester type acid dissociable, dissolution inhibiting group and acetal type acid dissociable, dissolution inhibiting group. And tertiary alkyl ester type acid dissociable, dissolution inhibiting groups are preferred.

In general formula (a1-0-2), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group, and the aliphatic cyclic group is the above except that a group in which two or more hydrogen atoms are removed is used. The thing similar to description of an "aliphatic cyclic group" can be used.

  More specifically, examples of the structural unit (a1) include structural units represented by the following general formulas (a1-1) to (a1-4).

［上記式中、Ｘ’は第３級アルキルエステル型酸解離性溶解抑制基を表し、Ｙは炭素数１〜５の低級アルキル基、または脂肪族環式基を表し；ｎは０〜３の整数を表し；Ｙ^２はアルキレン基または脂肪族環式基を表し；Ｒは前記と同じであり、Ｒ^１’、Ｒ^２’はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基を表す。］

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; Y ² represents an alkylene group or an aliphatic cyclic group; R is the same as defined above; R ¹ ′ and R ² ′ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; Represents. ]

In the R ¹ ′ and R ² ′, at least one is preferably a hydrogen atom, and more preferably both are hydrogen atoms. n is preferably 0 or 1.

X ′ is the same as the tertiary alkyl ester type acid dissociable, dissolution inhibiting group exemplified in X ¹ above.
Examples of the aliphatic cyclic group for Y include the same groups as those exemplified above in the description of “aliphatic cyclic group”.
Y ² is preferably an alkylene group having 1 to 10 carbon atoms or a divalent aliphatic cyclic group, except that a group in which two or more hydrogen atoms are removed is used as the aliphatic cyclic group. The same as described for the “aliphatic cyclic group” can be used. When Y ² is an alkylene group having 1 to 10 carbon atoms, it is more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. . When Y ² is a divalent aliphatic cyclic group, a group in which two or more hydrogen atoms have been removed from cyclopentane, cyclohexane, norbornane, isobornane, adamantane, tricyclodecane, or tetracyclododecane is particularly preferable. .

  Specific examples of the structural units represented by the general formulas (a1-1) to (a1-4) are shown below.

Among the above, the structural unit represented by the general formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) and (a1-1-35) to (a1). More preferably, at least one selected from the group consisting of -1-41) is used.
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formulas (a1-1-1) to (a1-1-4) The following general formula (a1-1-02) including the structural units of formulas (a1-1-35) to (a1-1-41) is also preferable.

（式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。）

(In the formula, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹¹ represents a lower alkyl group.)

（式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１２は低級アルキル基を示す。ｈは１〜３の整数を表す）

(In the formula, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, R ¹² represents a lower alkyl group, and h represents an integer of 1 to 3)

In general formula (a1-1-01), R is the same as defined above. The lower alkyl group for R ^{11 is the same as} the lower alkyl group for R, and is preferably a methyl group or an ethyl group.

In general formula (a1-1-02), R is the same as defined above. The lower alkyl group for R ^{12 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group. h is preferably 1 or 2, and most preferably 2.

In the polymer compound (A1), as the structural unit (a1), one type of structural unit may be used alone, or two or more types may be used in combination.
In the polymer compound (A1), as described above, the proportion of the structural unit (a1) is such that the total proportion of the structural unit (a0) and the structural unit (a1) constitutes the polymer compound (A1). The amount of 10 to 80 mol% is preferable with respect to the structural unit, the amount of 20 to 70 mol% is more preferable, and the amount of 25 to 50 mol% is most preferable. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.
When the structural unit (a0) and the structural unit (a1) are used at the same time, it is preferably used in the range of the structural unit (a0): the structural unit (a1) = 1: 9 to 9: 1 (molar ratio). The range of 9-7: 3 is more preferred, the range of 1: 9-5: 5 is particularly preferred, and the range of 1: 9-4: 6 is most preferred. By setting it in the above range, lithography characteristics such as LWR are improved.

<Structural unit (a2)>
The structural unit (a2) is a structural unit derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the 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.
When the positive resist composition containing the polymer compound (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate, This is effective in increasing the affinity with a developer containing the.

As the structural unit (a2), any unit can be used without any particular limitation.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring.

  More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数であり、Ａは炭素数１〜５のアルキレン基または酸素原子である。］

[Wherein, R is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is an integer of 0 or 1] And A is an alkylene group having 1 to 5 carbon atoms or an oxygen atom. ]

R in the general formulas (a2-1) to (a2-5) is the same as R in the structural unit (a1).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
Specific examples of the alkylene group having 1 to 5 carbon atoms of A include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

In the polymer compound (A1), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
As the structural unit (a2), at least one selected from the group consisting of structural units represented by the general formulas (a2-1) to (a2-5) is preferable, and the general formulas (a2-1) to (a2) -3) At least 1 sort (s) selected from the group which consists of a structural unit represented by 3) is more preferable. Among them, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3-2) ), (A2-3-9) or (a2-3-10), it is preferable to use at least one selected from the group consisting of structural units.

In the polymer compound (A1), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the polymer compound (A1) is preferably from 5 to 60 mol%, more preferably from 10 to 60 mol%, based on the total of all the structural units constituting the polymer compound (A1). Preferably, 20 to 60 mol% is more preferable. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

<Structural unit (a3)>
The structural unit (a3) is a structural unit derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.
When the polymer compound (A1) has the structural unit (a3), the hydrophilicity of the polymer compound (A1) is increased, and the affinity with the developer is increased. As a result, when the polymer compound (A1) is blended with the positive resist composition, the solubility of the resist film formed using the positive resist composition in the alkaline developer at the exposed portion is improved. And contributes to improvement of resolution.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). It is done. As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

  The structural unit (a3) is derived from a hydroxyethyl ester of acrylic acid when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms. When the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), (a3-3) ) Is preferable.

（式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数であり、ｔ’は１〜３の整数であり、ｌは１〜５の整数であり、ｓは１〜３の整数である。）

(Wherein R is the same as above, j is an integer of 1 to 3, k is an integer of 1 to 3, t 'is an integer of 1 to 3, and l is an integer of 1 to 5) And s is an integer of 1 to 3.)

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group is bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.
j is preferably 1, and a hydroxyl group bonded to the 3rd position of the adamantyl group is particularly preferred.

In formula (a3-2), k is preferably 1.
The cyano group is preferably bonded to the 5th or 6th position of the norbornyl group.

In formula (a3-3), t ′ is preferably 1. l is preferably 1. s is preferably 1.
These preferably have a 2-norbornyl group or a 3-norbornyl group bonded to the terminal of the carboxy group of acrylic acid.
The fluorinated alkyl alcohol is preferably bonded to the 5th or 6th position of the norbornyl group.

In the polymer compound (A1), as the structural unit (a3), one type of structural unit may be used alone, or two or more types may be used in combination.
In the polymer compound (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, and 5 to 40 mol% with respect to all the structural units constituting the polymer compound (A1). More preferably, 5-25 mol% is further more preferable.

<Structural unit (a4)>
The polymer compound (A1) may contain other structural units (a4) other than the structural units (a0) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1) to (a3) described above, and is for ArF excimer laser and KrF excimer laser (preferably ArF excimer). A number of hitherto known materials can be used for resist resins such as lasers.
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

(In the formula, R is as defined above.)

  When such a structural unit (a4) is contained in the polymer compound (A1), 1 to 30 mol% of the structural unit (a4) is contained with respect to the total of all the structural units constituting the polymer compound (A1). It is preferable to make it contain, and it is more preferable to make it contain 10-20 mol%.

The polymer compound (A1) is preferably a copolymer having at least the structural units (a0), (a2) and (a3). Examples of the copolymer include the structural units (a0), (a2) and A copolymer consisting of (a3), a copolymer consisting of structural units (a0), (a2), (a3) and (a4), from structural units (a0), (a2), (a3) and (a1) And a copolymer composed of structural units (a0), (a2), (a3), (a1) and (a4).
In the present invention, as the polymer compound (A1), in particular, a copolymer containing three structural units represented by the following general formula (A1-31), or four kinds represented by the following general formula (A1-41): A copolymer containing the structural unit is preferably used.

［式中、Ｒ、Ｒ^１はそれぞれ独立に水素原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ^１０は低級アルキル基であり、Ｒ^１１は低級アルキル基である。］

[Wherein, R and R ¹ each independently represent a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, R ¹⁰ represents a lower alkyl group, and R ¹¹ represents a lower alkyl group. ]

Wherein, R, ^{R 1,} the respective R, are the same as those for ^{R 1.} A plurality of R in the formula may be the same or different.
Examples of the lower alkyl group for R ¹⁰ include the same lower alkyl groups as those described above for R ^1. A methyl group or an ethyl group is preferable, and an ethyl group is particularly preferable.
Wherein ^{(A1-41), R 11} is the same as ^{R 11} in formula (a1-1-01), preferably a methyl group or an ethyl group, a methyl group is particularly preferred.

The polymer compound (A1) is obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using an azo radical polymerization initiator such as azobisisobutyronitrile (AIBN). Can be obtained.
Further, in the polymer compound (A1), a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination in the above polymerization. it may be introduced -C _{(CF 3)} 2 -OH group at the terminal. As described above, a resin having a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective for.

Although the mass mean molecular weight (Mw) (polystyrene conversion reference | standard by gel permeation chromatography) of a high molecular compound (A1) is not specifically limited, 2000-50000 are preferable, 3000-30000 are more preferable, 5000- 20000 is most preferred. If it is smaller than the upper limit of this range, there is sufficient solubility in a resist solvent to be used as a resist, and if it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) of the polymer compound (A1) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. Mn represents a number average molecular weight.

The polymer compound (A1) of the present invention is a novel compound not conventionally known.
For example, when the polymer compound (A1) is blended in a positive resist composition together with an acid generator component (B) that generates an acid upon irradiation with radiation, the acid generator component (B) upon exposure (irradiation with radiation). When an acid is generated from the oxygen atom, the bond between the oxygen atom bonded to the carbonyl group in the structural unit (a0) and the tertiary carbon atom on the octyl ring to which the oxygen atom is bonded is broken by the action of the acid. Is done. Further, when the polymer compound (A1) further has the structural unit (a1), dissociation of the acid dissociable, dissolution inhibiting group in the structural unit (a1) also occurs. As a result, the solubility of the polymer compound (A1) in the alkaline developer increases.
Therefore, the polymer compound (A1) is useful as a base resin for a chemically amplified positive resist composition, and can be suitably used as a base component (A) for the following positive resist composition of the present invention. .

≪Positive resist composition≫
The positive resist composition of the present invention comprises a base component (A) whose solubility in an alkaline developer is increased by the action of an acid (hereinafter referred to as component (A)), and an acid that generates an acid upon irradiation with radiation. Contains a generator component (B) (hereinafter referred to as component (B)). Here, the “base material component” is an organic compound having a film forming ability.
In such a positive resist composition, when radiation is irradiated (exposed), an acid is generated from the component (B), and the solubility of the component (A) in an alkaline developer is increased by the action of the acid. Therefore, in the formation of the resist pattern, when selective exposure is performed on the resist film obtained using the positive resist composition, the solubility of the resist film in the alkaline developer in the exposed portion increases. Since the solubility of the unexposed portion in the alkaline developer does not change, a resist pattern can be formed by performing alkali development.

<(A) component>
(A) A component contains the high molecular compound (A1) of this invention mentioned above.
In the component (A), the polymer compound (A1) may be used alone or in combination of two or more.
The proportion of the polymer compound (A1) in the component (A) is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and 100% by mass with respect to the total mass of the component (A). Good.

Component (A) is a “base component whose solubility in an alkaline developer is increased by the action of an acid” (hereinafter referred to as component (A2)) other than the polymer compound (A1) as long as the effects of the present invention are not impaired. May be contained).
The component (A2) is not particularly limited, and many conventionally known base components for chemically amplified positive resist compositions (for example, for ArF excimer laser, for KrF excimer laser (preferably A base resin such as ArF excimer laser) may be arbitrarily selected and used. For example, the base resin for ArF excimer laser includes those having the structural unit (a1) as an essential structural unit and optionally further including the structural units (a2) to (a4).
(A2) A component may be used individually by 1 type and may be used in combination of 2 or more type.

<(B) component>
The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists can be used. 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, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  As the onium salt acid generator, for example, a compound represented by the following general formula (b-1) or (b-2) can be used.

［式中、Ｒ^１”〜Ｒ^３”，Ｒ^５”〜Ｒ^６”は、それぞれ独立に、アリール基またはアルキル基を表し；式（ｂ−１）におけるＲ^１”〜Ｒ^３”のうち、いずれか２つが相互に結合して式中のイオウ原子と共に環を形成してもよく；Ｒ^４”は、置換基を有していても良い直鎖状、分岐鎖状または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[Wherein, R ¹ ″ to R ³ ″ and R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group; among R ¹ ″ to R ³ ″ in formula (b-1), Any two may be bonded to each other to form a ring together with the sulfur atom in the formula; R ⁴ ″ may be a linear, branched or cyclic alkyl group which may have a substituent or Represents a fluorinated alkyl group; at least one of R ¹ ″ to R ³ ″ represents an aryl group, and at least one of R ⁵ ″ to R ⁶ ″ represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. In addition, any two of R ¹ ″ to R ³ ″ in formula (b-1) may be bonded to each other to form a ring together with the sulfur atom in the formula.
Further, at least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom, a hydroxyl group or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
As the alkoxy group that may be substituted for the hydrogen atom of the aryl group, an alkoxy group having 1 to 5 carbon atoms is preferable, and a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, Most preferred is a tert-butoxy group.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may be substituted for the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, linear C1-10, branched or cyclic alkyl group, and the like. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are most preferably a phenyl group or a naphthyl group, respectively.

When any two of R ¹ ″ to R ³ ″ in the formula (b-1) are bonded to each other to form a ring together with the sulfur atom in the formula, a 3 to 10 membered ring including the sulfur atom is formed. It is preferable that a 5- to 7-membered ring is formed.
When any two of R ¹ ″ to R ³ ″ in formula (b-1) are bonded to each other to form a ring together with the sulfur atom in the formula, the remaining one may be an aryl group preferable. Examples of the aryl group include the same aryl groups as R ¹ ″ to R ³ ″.

R ⁴ ″ represents a linear, branched or cyclic alkyl group or fluorinated alkyl group which may have a substituent.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. A fluorinated alkyl group (perfluoroalkyl group) is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.
Examples of the substituent that R ⁴ ″ may have include an aryl group, an alkenyl group, an aliphatic cyclic group, a general formula: R ¹¹ ″ —CH ₂ —O— [wherein R ¹¹ ″ is a monovalent group. Or an alkenyl group having 1 to 5 carbon atoms.] Or the like.
The aryl group is the same as the aryl group of R ¹ ″ to R ³ ″ described above, and is preferably a phenyl group or a naphthyl group.
As an alkenyl group, a C1-C5 alkenyl group is preferable and a vinyl group and a propenyl group are preferable.
The aliphatic cyclic group is the same as the above-described aliphatic cyclic group (paragraph [0022]), and is preferably an adamantyl group or a norbornyl group.
Examples of the monovalent aromatic organic group represented by R ¹¹ ″ include a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and the like. Aryl groups from which one hydrogen atom has been removed; heteroaryl groups in which some of the carbon atoms constituting the ring of these aryl groups are substituted with heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms; benzyl groups, phenethyl groups The number of carbon atoms of the alkyl chain in the arylalkyl group is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 to 2. .
These aryl group, heteroaryl group, and arylalkyl group may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom, and a fluorine atom is preferable.
The carbon number of the monovalent aromatic organic group for R ¹¹ ″ is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 10.
The alkenyl group having 1 to 5 carbon atoms of R ¹¹ ″ is preferably a vinyl group or a propenyl group.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. It is preferable that all of R ⁵ ″ to R ⁶ ″ are aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
Examples of the alkyl group for R ⁵ ″ to R ⁶ ″ include the same as the alkyl group for R ¹ ″ to R ³ ″.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.
"As ^{R 4} in the formula (b-1)" ^{R 4} in the In the formula (b-2) include the same as.

Specific examples of the onium salt acid generators represented by formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethane sulfonate or nonafluorobutane sulfonate, triphenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Sulfonate or its nonafluorobutane sulfonate, di (1-naphthyl) phenyl sulphonium trifluoromethane sulphonate, its heptafluoropropane sulphonate or its nonafluorobutane sulphonate; 1-phenyltetrahydrothiophenium trifluoromethane sulphonate, its heptafluoropropane sulphonate Or nonafluorobutanesulfonate thereof; 1- (4-methylphenyl) ) Tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropane sulfonate 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; 1- (4-ethoxynaphthalene-1- Yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonaflu 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; 1-phenyltetrahydrothiopyranium trifluoromethanesulfonate , Its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (4-hydroxyphenyl) tetrahydrothiopyranium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1- (3,5-dimethyl -4-Hydroxyphenyl) tetrahydrothiopyranium trifluoromethanesulfonate, its heptafluoropropanes Honeto or nonafluorobutanesulfonate; 1- (4-methylphenyl) trifluoromethanesulfonate tetrahydrothiophenium Pila chloride, heptafluoropropane sulfonate or its nonafluorobutane sulfonate, and the like.
In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

  In addition, in the general formula (b-1) or (b-2), an onium salt-based acid generator in which the anion moiety is replaced with an anion moiety represented by the following general formula (b-3) or (b-4). Can also be used (the cation moiety is the same as (b-1) or (b-2)).

［式中、Ｘ”は、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｙ”、Ｚ”は、それぞれ独立に、少なくとも１つの水素原子がフッ素原子で置換された炭素数１〜１０のアルキル基を表す。］

[Wherein X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; Y ″ and Z ″ each independently represent at least one hydrogen atom as a fluorine atom; Represents an alkyl group having 1 to 10 carbon atoms and substituted with

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Most preferably, it has 3 carbon atoms.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably Has 1 to 7 carbon atoms, more preferably 1 to 3 carbon atoms.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, as the number of hydrogen atoms substituted with fluorine atoms increases, the strength of the acid increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Moreover, the sulfonium salt which has a cation part represented by the following general formula (b-5) or (b-6) can also be used as an onium salt type | system | group acid generator.

［式中、Ｒ^４１〜Ｒ^４６はそれぞれ独立してアルキル基、アセチル基、アルコキシ基、カルボキシ基、水酸基またはヒドロキシアルキル基であり；ｎ_１〜ｎ_５はそれぞれ独立して０〜３の整数であり、ｎ_６は０〜２の整数である。］

[Wherein R ^{41 to} R ⁴⁶ are each independently an alkyl group, acetyl group, alkoxy group, carboxy group, hydroxyl group or hydroxyalkyl group; n _{1 to} n ₅ are each independently an integer of 0 to 3; There, _{n 6} is an integer of 0-2. ]

In R ^{41 to} R ⁴⁶ , the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group, and a methyl group, an ethyl group, a propyl group, an isopropyl group, n A butyl group or a tert-butyl group is particularly preferable.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a linear or branched alkoxy group, and particularly preferably a methoxy group or an ethoxy group.
The hydroxyalkyl group is preferably a group in which one or more hydrogen atoms in the alkyl group are substituted with a hydroxy group, and examples thereof include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group.
When the symbols n _{1 to} n ₆ attached to R ^{41 to} R ⁴⁶ are integers of 2 or more, the plurality of R ^{41 to} R ⁴⁶ may be the same or different.
n ₁ is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0.
n ₂ and n ₃ are preferably each independently 0 or 1, more preferably 0.
n ₄ is preferably 0 to 2, more preferably 0 or 1.
n ₅ is preferably 0 or 1, more preferably 0.
n ₆ is preferably 0 or 1, more preferably 1.

The anion part of the sulfonium salt having a cation part represented by the formula (b-5) or (b-6) is not particularly limited, and is the same as the anion part of the onium salt acid generators proposed so far. It may be a thing. Examples of the anion moiety include fluorinated alkyl sulfonate ions such as the anion moiety (R ^{4 ″} SO ₃ ⁻ ) of the onium salt acid generator represented by the general formula (b-1) or (b-2). An anion moiety represented by the general formula (b-3) or (b-4), etc. Among them, a fluorinated alkyl sulfonate ion is preferable, and a fluorinated alkyl sulfonic acid having 1 to 4 carbon atoms. Ion is more preferable, and linear perfluoroalkylsulfonic acid ions having 1 to 4 carbon atoms are particularly preferable, and specific examples thereof include trifluoromethylsulfonic acid ions, heptafluoro-n-propylsulfonic acid ions, and nonafluoro-n. -Butyl sulfonate ion etc. are mentioned.

  In this specification, the oxime sulfonate acid generator is a compound having at least one group represented by the following general formula (B-1), and has a property of generating an acid upon irradiation with radiation. is there. Such oxime sulfonate-based acid generators are frequently used for chemically amplified resist compositions, and can be arbitrarily selected and used.

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

(In formula (B-1), R ³¹ and R ³² each independently represents an organic group.)

The organic groups of R ³¹ and R ³² are groups containing carbon atoms, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms (fluorine atoms, chlorine atoms, etc.), etc.) You may have.
As the organic group for R ^31, a linear, branched, or cyclic alkyl group or aryl group is preferable. These alkyl groups and aryl groups may have a substituent. There is no restriction | limiting in particular as this substituent, For example, a fluorine atom, a C1-C6 linear, branched or cyclic alkyl group etc. are mentioned. Here, “having a substituent” means that part or all of the hydrogen atoms of the alkyl group or aryl group are substituted with a substituent.
As an alkyl group, C1-C20 is preferable, C1-C10 is more preferable, C1-C8 is more preferable, C1-C6 is especially preferable, and C1-C4 is the most preferable. As the alkyl group, a partially or completely halogenated alkyl group (hereinafter sometimes referred to as a halogenated alkyl group) is particularly preferable. The partially halogenated alkyl group means an alkyl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated alkyl group means that all of the hydrogen atoms are halogen atoms. Means an alkyl group substituted with Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.
The aryl group preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the aryl group, a partially or completely halogenated aryl group is particularly preferable. The partially halogenated aryl group means an aryl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated aryl group means that all of the hydrogen atoms are halogen atoms. Means an aryl group substituted with.
R ³¹ is particularly preferably an alkyl group having 1 to 4 carbon atoms having no substituent or a fluorinated alkyl group having 1 to 4 carbon atoms.

As the organic group for R ^32, a linear, branched, or cyclic alkyl group, aryl group, or cyano group is preferable. As the alkyl group and aryl group for R ^32, the same alkyl groups and aryl groups as those described above for R ³¹ can be used.
R ³² is particularly preferably a cyano group, an alkyl group having 1 to 8 carbon atoms having no substituent, or a fluorinated alkyl group having 1 to 8 carbon atoms.

  More preferable examples of the oxime sulfonate-based acid generator include compounds represented by the following general formula (B-2) or (B-3).

［式（Ｂ−２）中、Ｒ^３３は、シアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３４はアリール基である。Ｒ^３５は置換基を有さないアルキル基またはハロゲン化アルキル基である。］

[In Formula (B-2), R ³³ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁴ is an aryl group. R ³⁵ represents an alkyl group having no substituent or a halogenated alkyl group. ]

［式（Ｂ−３）中、Ｒ^３６はシアノ基、置換基を有さないアルキル基またはハロゲン化アルキル基である。Ｒ^３７は２または３価の芳香族炭化水素基である。Ｒ^３８は置換基を有さないアルキル基またはハロゲン化アルキル基である。ｐ”は２または３である。］

[In Formula (B-3), R ³⁶ represents a cyano group, an alkyl group having no substituent, or a halogenated alkyl group. R ³⁷ is a divalent or trivalent aromatic hydrocarbon group. ^R38 is an alkyl group having no substituent or a halogenated alkyl group. p ″ is 2 or 3.]

In the general formula (B-2), the alkyl group or halogenated alkyl group having no substituent of R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and carbon atoms. Numbers 1 to 6 are most preferable.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³³ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred.

As the aryl group of R ³⁴ , one hydrogen atom is removed from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, or a phenanthryl group. And heteroaryl groups in which some of the carbon atoms constituting the ring of these groups are substituted with heteroatoms such as oxygen, sulfur, and nitrogen atoms. Among these, a fluorenyl group is preferable.
The aryl group of R ³⁴ may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or an alkoxy group. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group.

The alkyl group or halogenated alkyl group having no substituent for R ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³⁵ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred is the strength of the acid generated. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

In the general formula (B-3), the alkyl group or halogenated alkyl group having no substituent for R ³⁶ is the same as the alkyl group or halogenated alkyl group having no substituent for R ^33. Is mentioned.
Examples of the divalent or trivalent aromatic hydrocarbon group for R ³⁷ include groups obtained by further removing one or two hydrogen atoms from the aryl group for R ³⁴ .
Examples of the alkyl group or halogenated alkyl group having no substituent of R ³⁸ include the same alkyl groups or halogenated alkyl groups as those having no substituent of R ³⁵ .
p ″ is preferably 2.

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

  Of the above exemplified compounds, the following four compounds are 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.
Further, diazomethane acid generators disclosed in JP-A-11-035551, JP-A-11-035552, and JP-A-11-035573 can also be suitably used.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane and 1,4-bis (phenylsulfonyldiazo) disclosed in JP-A-11-322707. Methylsulfonyl) butane, 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane, 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane, 1,3 -Bis (cyclohexylsulfonyldiazomethylsulfonyl) propane, 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane, etc. Door can be.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, an onium salt having a fluorinated alkyl sulfonate ion as an anion is preferably used as the component (B).
0.5-30 mass parts is preferable with respect to 100 mass parts of (A) component, and, as for content of (B) component in the positive resist composition of this invention, 1-10 mass parts is more preferable. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<Optional component>
In the positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Can be blended.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, etc .; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, alkyl alcohol amines and trialkyl amines are preferable, and trialkyl amines are more preferable. Among the trialkylamines, trialkylamines having 5 to 10 carbon atoms are more preferable, and tri-n-pentylamine is most preferable.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
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.

The positive resist composition of the present invention includes, as optional components, organic carboxylic acids, phosphorus oxoacids and derivatives thereof for the purpose of preventing sensitivity deterioration, improving the resist pattern shape, stability over time, etc. At least one compound (E) selected from the group consisting of (hereinafter referred to as component (E)) can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of the phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
(E) A component may be used individually by 1 type and may use 2 or more types together.
As the component (E), an organic carboxylic acid is preferable, and salicylic acid is particularly preferable.
(E) A component is normally used in the ratio of 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

  If desired, the positive resist composition of the present invention may further contain miscible additives such as an additional resin for improving the performance of the resist film, a surfactant for improving coating properties, and a dissolution inhibitor. An agent, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether [in these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME) Is preferred];
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate;
Aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene, etc. be able to.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
As the component (S), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is also 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 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), 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.
The amount of the component (S) used is not particularly limited, but is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 3-15% by mass.

The positive resist composition of the present invention is a novel one that has not been known so far.
Moreover, according to the positive resist composition of the present invention, a resist pattern with a small LWR can be formed. Furthermore, the positive resist composition of the present invention has good sensitivity and resolution.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention comprises a step of forming a resist film on a support using the positive resist composition of the present invention, a step of exposing the resist film, and an alkali developing of the resist film to form a resist. Forming a pattern.

  The resist pattern forming method of the present invention can be performed, for example, as follows. That is, first, the positive resist composition is coated on a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90, under a temperature condition of 80 to 150 ° C. For example, ArF excimer laser light is selectively exposed through a desired mask pattern using an ArF exposure apparatus or the like, and then subjected to PEB (post-exposure heating) at a temperature of 80 to 150 ° C. for 40 to 120. Second, preferably 60-90 seconds. Subsequently, this is developed with an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide, preferably rinsed with pure water and dried. In some cases, a baking process (post-bake) may be performed after the development process. In this way, a resist pattern faithful to the mask pattern can be obtained.

The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
Further, the support may be a substrate in which an inorganic and / or organic film is provided on the above-described substrate. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include an organic antireflection film (organic BARC).
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. Among these, the positive resist composition is effective for KrF excimer laser, ArF excimer laser, EB or EUV, particularly ArF excimer laser.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
In the following Reference Example 1, Example 2, and Comparative Examples 1 and 2, compounds (1) to (6) represented by the following formulas (1) to (6) were used as monomers.

[Reference Example 1]
17.00 g of the compound (1), 22.40 g of the compound (2), and 11.80 of the compound (3) were dissolved in 76.80 g of ethyl lactate. To this solution, 15 mmol of Wako Pure Chemical V-601 (polymerization initiator) was added and dissolved. The resultant was dropwise added to 42.67 g of ethyl lactate heated to 80 ° C. in a nitrogen atmosphere over 6 hours. After completion of dropping, the reaction solution was heated and stirred for 1 hour, and then the reaction solution was cooled to room temperature. Thereafter, the operation of dropping the reaction solution into a large amount of methanol / water solution and precipitating the copolymer was repeated twice. The copolymer thus obtained was dried under reduced pressure at room temperature to obtain a white powder. This is polymer compound 1, and the structural formula is shown below.
As a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR) of this polymer compound 1, the polymer composition (ratio (molar ratio) of each structural unit in the structural formula) was 1 / m / n = 41. 0.0 / 40.5 / 18.5. Moreover, the standard polystyrene conversion mass mean molecular weight calculated | required by GPC measurement was 5,900, and dispersion degree was 1.67.

[Example 2]
17.76 g of the compound (4), 3.58 g of the compound (2), 9.36 g of the compound (5) and 5.67 g of the compound (3) were dissolved in 145.44 g of methyl ethyl ketone. To this solution, 8.8 mmol of Wako Pure Chemical V-601 (polymerization initiator) was added and dissolved. The resultant was dropwise added to 60.61 g of methyl ethyl ketone heated to 80 ° C. in a nitrogen atmosphere over 6 hours. After completion of dropping, the reaction solution was heated and stirred for 1 hour, and then the reaction solution was cooled to room temperature. Thereafter, the operation of dropping the reaction solution into a large amount of methanol / water solution and precipitating the copolymer was repeated twice. The copolymer thus obtained was dried under reduced pressure at room temperature to obtain a white powder. This is referred to as polymer compound 7, and the structural formula is shown below.
As a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR) of the polymer compound 7, the polymer composition (ratio (molar ratio) of each structural unit in the structural formula) was 1 / m / n / o. = 52.2 / 9.4 / 22.3 / 16.1. Further, the mass average molecular weight in terms of standard polystyrene determined by GPC measurement was 6,400, and the degree of dispersion was 1.61.

[Comparative Example 1]
17.00 g of the compound (1), 19.60 g of the compound (6), and 11.80 of the compound (3) were dissolved in 72.60 g of ethyl lactate. To this solution, 15 mmol of Wako Pure Chemical V-601 (polymerization initiator) was added and dissolved. The resultant was dropwise added to 40.33 g of ethyl lactate heated to 80 ° C. in a nitrogen atmosphere over 6 hours. After completion of dropping, the reaction solution was heated and stirred for 1 hour, and then the reaction solution was cooled to room temperature. Thereafter, the operation of dropping the reaction solution into a large amount of methanol / water solution and precipitating the copolymer was repeated twice. The copolymer thus obtained was dried under reduced pressure at room temperature to obtain a white powder. This is referred to as polymer compound 10, and the structural formula thereof is shown below.
As a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR) of this polymer compound 10, the polymer composition (ratio (molar ratio) of each structural unit in the structural formula) was 1 / m / n = 43. 0.0 / 40.0 / 17.0. Moreover, the standard polystyrene conversion mass mean molecular weight calculated | required by GPC measurement was 5,800, and dispersion degree was 1.60.

[Comparative Example 2]
17.76 g of the compound (4), 3.14 g of the compound (6), 9.36 g of the compound (5) and 5.67 g of the compound (3) were dissolved in 143.68 g of methyl ethyl ketone. To this solution, 8.8 mmol of Wako Pure Chemical V-601 (polymerization initiator) was added and dissolved. The resultant was dropwise added to 59.87 g of methyl ethyl ketone heated to 80 ° C. in a nitrogen atmosphere over 6 hours. After completion of dropping, the reaction solution was heated and stirred for 1 hour, and then the reaction solution was cooled to room temperature. Thereafter, the operation of dropping the reaction solution into a large amount of methanol / water solution and precipitating the copolymer was repeated twice. The copolymer thus obtained was dried under reduced pressure at room temperature to obtain a white powder. This is referred to as polymer compound 11, and the structural formula thereof is shown below.
As a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR) of the polymer compound 11, the polymer composition (ratio (molar ratio) of each structural unit in the structural formula) was 1 / m / n / o. = 52.0 / 9.0 / 24.5 / 14.5. Moreover, the standard polystyrene conversion mass mean molecular weight calculated | required by GPC measurement was 7,500, and dispersion degree was 1.72.

[Reference Example 3, Example 4, Comparative Examples 3 to 4]
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(A) -1: Polymer compound 1 of Reference Example 1.
(A ′)-1: the polymer compound 10 of Comparative Example 1.
(A) -2: polymer compound 7 of Example 2.
(A ′)-2: the polymer compound 11 of Comparative Example 2.
(B) -1: Triphenylsulfonium heptafluoro-n-propanesulfonate.
(B) -2: Di (1-naphthyl) phenylsulfonium nonafluoro-n-butanesulfonate.
(D) -1: tri-n-pentylamine.
(E) -1: salicylic acid.
(S) -1: γ-butyrolactone.
(S) -2: Mixed solvent of PGMEA / PGME = 6/4 (mass ratio).

  The following evaluation was performed using the obtained positive resist composition solution.

<Formation of resist pattern>
An organic antireflective coating composition “ARC95” (trade name, manufactured by Brewer Science) is applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a thickness of 77 nm was formed.
Then, the positive resist composition obtained above was applied onto the organic antireflection film using a spinner, and prebaked (PAB) for 60 seconds at a PAB temperature shown in Table 2 on a hot plate. ) A resist film having a film thickness of 150 nm was formed by performing treatment and drying.
Next, an ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, 2/3 annular illumination). . Then, a post-exposure heating (PEB) treatment is performed for 60 seconds at the PEB temperature shown in Table 2, followed by a development treatment with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution at 23 ° C. for 30 seconds, and then Water rinsing was performed using pure water for 30 seconds, followed by drying by shaking.
As a result, a line-and-space resist pattern (L / S pattern) having a line width of 120 nm and a pitch of 240 nm was formed in any example using any positive resist composition.
At this time, the optimum exposure dose Eop (mJ / cm ² ) at which an L / S pattern having a line width of 120 nm and a pitch of 240 nm was formed, that is, sensitivity was obtained. The results are shown in Table 2.

<Evaluation of LWR>
In each L / S pattern formed by the Eop, five points were measured in the longitudinal direction of the line with a length measurement SEM (scanning electron microscope, acceleration voltage 800 V, trade name: S-9220, manufactured by Hitachi, Ltd.). From the results, a standard deviation (s) triple value (3 s) was calculated as a measure of LWR. The results are shown in Table 2.
Note that the smaller the value of 3s, the smaller the roughness of the line width, which means that a resist pattern with a more uniform width was obtained.

As is clear from the results in Table 2, according to the positive resist composition of Reference Example 3 using Polymer Compound 1, Comparative Example 3 using Polymer Compound 10 which is the same ternary copolymer was used. Compared to the positive resist composition, a resist pattern having a more uniform width was obtained.
Moreover, according to the positive resist composition of Example 4 using the polymer compound 7, compared with the positive resist composition of Comparative Example 4 using the polymer compound 11 which is the same quaternary copolymer. Thus, a resist pattern having a more uniform width was obtained.

Claims (8)

A positive resist composition comprising a base component (A) whose solubility in an alkali developer is increased by the action of an acid, and an acid generator component (B) that generates an acid upon irradiation with radiation,
The base material component (A) contains a polymer compound (A1),
The polymer compound (A1) is a structural unit (a0) represented by the following general formula (a0-1), a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, A structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, not corresponding to the structural unit (a0),
A positive type wherein the molar ratio between the structural unit (a0) and the structural unit (a1) is in the range of the structural unit (a0): the structural unit (a1) = 1: 9 to 4: 6. Resist composition.

[In Formula (a0-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, R ⁵ is an alkyl group, and R ⁶ is an alkyl group. And a substituent selected from the group consisting of an alkoxy group, a halogen atom, and a halogenated alkyl group, and e is an integer of 0 to 5. ]   The ratio of the structural unit (a0) to the total structural unit constituting the polymer compound (A1) is 1 mol% or more, and the total ratio of the structural unit (a0) and the structural unit (a1) is 10%. 2. The positive resist composition according to claim 1, wherein the composition is ˜80 mol%, and the proportion of the structural unit (a2) is 5˜60 mol%.   The polymer compound (A1) further contains a polar group selected from the group consisting of a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. The positive resist composition according to claim 1, which has a structural unit (a3) derived from an acrylate ester containing an aliphatic hydrocarbon group.   Furthermore, the positive resist composition as described in any one of Claims 1-3 containing a nitrogen-containing organic compound (D).   A step of forming a resist film on a support using the positive resist composition according to claim 1, a step of exposing the resist film, and an alkali developing of the resist film to form a resist A resist pattern forming method including a step of forming a pattern. The structural unit (a0) represented by the following general formula (a0-1), the structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, and not corresponding to the structural unit (a0), A structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group,
A polymer having a molar ratio of the structural unit (a0) to the structural unit (a1) in the range of the structural unit (a0): the structural unit (a1) = 1: 9 to 4: 6. Compound.

[In Formula (a0-1), R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, R ⁵ is an alkyl group, and R ⁶ is an alkyl group. And a substituent selected from the group consisting of an alkoxy group, a halogen atom, and a halogenated alkyl group, and e is an integer of 0 to 5. ]   The ratio of the structural unit (a0) to the total structural units constituting the polymer compound is 1 mol% or more, and the total ratio of the structural unit (a0) and the structural unit (a1) is 10 to 80 mol. The polymer compound according to claim 6, wherein the proportion of the structural unit (a2) is 5 to 60 mol%.   Further, acrylic acid containing an aliphatic hydrocarbon group containing a polar group selected from the group consisting of a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, and an alkyl group is substituted with a fluorine atom The polymer compound according to claim 6 or 7, which has a structural unit (a3) derived from an ester.