JP5238399B2 - Positive resist composition, resist pattern forming method, polymer compound, compound - Google Patents

Description

  The present invention relates to a novel polymer compound that can be used as a base component of a positive resist composition, a compound useful as a monomer of the polymer compound, a positive resist composition containing the polymer compound, and the positive type The present invention relates to a resist pattern forming method using a 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.
A resist material in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist material that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
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 lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions.
As a resist material satisfying such requirements, a chemically amplified resist composition containing a base material component 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. ing.
For example, as a positive chemically amplified resist composition, a composition containing a resin component (base resin) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component is generally used. Yes. When such a resist film formed using the resist composition is selectively exposed at the time of forming the resist pattern, an acid is generated from the acid generator in the exposed portion, and the alkali developer of the resin component is generated by the action of the acid. As a result, the exposed area becomes soluble in an alkaline developer.
Currently, as a resist base resin used in ArF excimer laser lithography and the like, a resin having a constitutional unit derived from (meth) acrylic acid ester (acrylic resin) because of its excellent transparency near 193 nm Etc. are generally used (see, for example, Patent Documents 1 and 2). 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.
JP 2003-241385 A JP 2006-016379 A

In the future, there is a demand for new materials that can be used for lithography applications as further advancement of lithography technology and expansion of application fields are expected.
In recent years, a problem that has become important in the field of lithography is a defect that occurs on the surface of a resist pattern. Defects are general defects detected when a developed resist pattern is observed from directly above, for example, with a surface defect observation apparatus (trade name “KLA”) manufactured by KLA Tencor. Examples of such defects include scum, bubbles, dust, bridges (bridge structures between resist patterns), uneven color, and precipitates after development. Improving the defect becomes important as a resist pattern having high resolution is required. In particular, when an ArF excimer laser is used, that is, when a fine pattern such as a resist pattern of 130 nm or less is formed using ArF excimer laser, F ₂ excimer laser, EUV, EB, etc. as a light source, the problem of defect resolution becomes more severe. ing. Therefore, as the resist pattern becomes finer, the demand for a material effective for reducing defects is increasing.
The present invention has been made in view of the above circumstances, and includes a novel polymer compound useful as a base component of a positive resist composition, a compound useful as a monomer of the polymer compound, and the polymer compound. It is an object of the present invention to provide a positive resist composition containing the resist and a method of forming a resist pattern 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 is a positive type containing 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 exposure. A resist composition comprising:
A positive resist composition comprising the base material component (A) containing a polymer compound (A1) having a structural unit (a0) represented by the following general formula (a0-1 -1 ): is there.

［式中、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 ^２ は、置換基を有していてもよい２価の脂肪族炭化水素基であって、隣接する酸素原子に結合する炭素原子が第３級炭素原子であり；Ｒ ^３ は直鎖状または分岐鎖状のアルキレン基であり；Ｒ^４はアセタール型酸解離性溶解抑制基である。］

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ]

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 a polymer compound having a structural unit (a0) represented by the following general formula (a0-1 -1 ).

［式中、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 ^２ は、置換基を有していてもよい２価の脂肪族炭化水素基であって、隣接する酸素原子に結合する炭素原子が第３級炭素原子であり；Ｒ ^３ は直鎖状または分岐鎖状のアルキレン基であり；Ｒ^４はアセタール型酸解離性溶解抑制基である。］

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ]

4th aspect of this invention is a compound represented by the following general formula (I <-1> ).

［式中、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 ^２ は、置換基を有していてもよい２価の脂肪族炭化水素基であって、隣接する酸素原子に結合する炭素原子が第３級炭素原子であり；Ｒ ^３ は直鎖状または分岐鎖状のアルキレン基であり；Ｒ^４はアセタール型酸解離性溶解抑制基である。］

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ]

In the present specification and claims, “aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do not have aromaticity.
The “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
Unless otherwise specified, the “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups. The same applies to the alkyl group in the alkoxy group.
The “halogenated alkyl group” is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
“Fluorinated alkyl group” or “fluorinated alkylene group” refers to a group in which part or all of the hydrogen atoms of an alkyl group or alkylene group are substituted with fluorine atoms.
“Structural unit” means a monomer unit (monomer unit) constituting a polymer compound (resin, polymer, copolymer).
“A structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent bonded to the α-position carbon atom include an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, and a hydroxyalkyl group. Hereinafter, the alkyl group having 1 to 5 carbon atoms and the halogenated alkyl group having 1 to 5 carbon atoms may be referred to as a lower alkyl group and a halogenated lower alkyl group, respectively. The α-position carbon atom of the acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.
“Exposure” is a concept including general irradiation of radiation.

  According to the present invention, a novel polymer compound that can be used as a base component of a positive resist composition, a compound useful as a monomer of the polymer compound, a positive resist composition containing the polymer compound, and the A resist pattern forming method using a positive resist composition can be provided.

≪Positive resist composition≫
The positive resist composition of the present invention (hereinafter sometimes referred to simply as “resist composition”) is a base component (A) (hereinafter referred to as “component (A)”) whose solubility in an alkaline developer is increased by the action of an acid. And an acid generator component (B) (hereinafter referred to as component (B)) that generates an acid upon irradiation with radiation.
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.
Here, the “base material component” is an organic compound having a film forming ability. As the substrate component, an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film-forming ability is improved and a nano-level resist pattern is easily formed.
“Organic compounds having a molecular weight of 500 or more” used as the base component are roughly classified into non-polymers and polymers.
As the non-polymer, those having a molecular weight of 500 or more and less than 4000 are usually used. Hereinafter, a nonpolymer having a molecular weight of 500 or more and less than 4000 is referred to as a low molecular compound.
As the polymer, those having a molecular weight of 2000 or more are usually used. Hereinafter, a polymer having a molecular weight of 2000 or more is referred to as a polymer compound. In the case of a polymer compound, the “molecular weight” is a polystyrene-reduced mass average molecular weight measured by GPC (gel permeation chromatography). Hereinafter, the polymer compound may be simply referred to as “resin”.

<(A) component>
[Polymer Compound (A1)]
(A) component contains the high molecular compound (A1) (henceforth (A1) component) which has the structural unit (a0) represented by the said general formula (a0-1).
The resist composition of the present invention is effective in reducing defects by containing the component (A1) having the structural unit (a0). The reason is considered as follows. That is, when selective exposure through a mask is performed on the resist film, a small amount of radiation may be irradiated even on an unexposed portion. For example, when selective exposure is performed through a halftone phase shift mask, the unexposed portion is irradiated with radiation of about several to 10% of the exposed portion, usually about 6%. Therefore, even in the unexposed area, a small amount of acid is generated from the component (B) according to the irradiation amount.
In the structural unit (a0), the bond between R ⁴ in formula (a0-1) and the oxygen atom (—O—) to which R ⁴ is bonded (hereinafter referred to as R ⁴ —O bond) is as follows. , X and an oxygen atom (—O—) bonded to a carbonyl group adjacent to X (hereinafter referred to as an X—O bond), which is relatively easy to cleave, 6% It is possible to cut even an unexposed portion when selective exposure is performed through a halftone phase shift mask. On the other hand, the X-O bond is relatively difficult to cut, and when selective exposure through a 6% halftone phase shift mask is performed, it is cut at the exposed portion but not at the unexposed portion.
Therefore, when selective exposure through a 6% halftone phase shift mask is performed in the formation of the resist pattern, the X—O bond (and the R ⁴ —O bond) is cut in the exposed portion, while carboxy group in a side chain terminal of the structural unit (a0) is formed, in the unexposed area, and R ^4, only the bond between the oxygen atom to which the R ⁴ is bonded (-O-) is cut Thus, an alcoholic hydroxyl group is formed at the end of the side chain of the structural unit (a0).
Thus, in the unexposed area, the formation of an alcoholic hydroxyl group in the component (A1) increases the hydrophilicity of the resist film in the unexposed area and improves the affinity for an alkali developer (alkaline aqueous solution). Thus, it is presumed that the occurrence of defects can be suppressed.

［式中、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；Ｘは、置換基を有していてもよい２価の脂肪族炭化水素基であって、隣接する酸素原子のうち、カルボニル基に結合した酸素原子に結合する炭素原子が第３級炭素原子であり；Ｒ ^４ はアセタール型酸解離性溶解抑制基である。］
式（ａ０−１）中、Ｒ^１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る。
Ｒ^１の低級アルキル基は、炭素数１〜５の直鎖状または分岐鎖状のアルキル基が好ましく、具体的には、メチル基、エチル基、プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、イソペンチル基、ネオペンチル基等が挙げられる。
Ｒ^１のハロゲン化低級アルキル基は、前記低級アルキル基の水素原子の一部または全部がハロゲン原子で置換された基である。該ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子等が挙げられ、特にフッ素原子が好ましい。
Ｒ^１としては、水素原子、低級アルキル基またはフッ素化低級アルキル基が好ましく、工業上の入手の容易さから、水素原子またはメチル基が最も好ましい。

[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms; X represents a divalent aliphatic carbon atom which may have a substituent; Among the adjacent oxygen atoms, the carbon atom bonded to the oxygen atom bonded to the carbonyl group is a tertiary carbon atom; R ⁴ is an acetal type acid dissociable, dissolution inhibiting group. ]
In formula (a0-1), R ¹ represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group.
The lower alkyl group for R ¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group. Group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like.
The halogenated lower alkyl group for R ¹ is a group in which part or all of the hydrogen atoms of the lower alkyl group are 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.

X is a divalent aliphatic hydrocarbon group which may have a substituent, and among adjacent oxygen atoms (—O—), the carbon atom bonded to the oxygen atom bonded to the carbonyl group is the first. A tertiary carbon atom.
Here, in the present specification and claims, the “aliphatic hydrocarbon group” means a hydrocarbon group having no aromaticity.
The aliphatic hydrocarbon group for X may be saturated or unsaturated, and is usually preferably saturated.
Specific examples of the aliphatic hydrocarbon group for X include a branched aliphatic hydrocarbon group and an aliphatic hydrocarbon group containing a ring in the structure.

The branched aliphatic hydrocarbon group in X is not particularly limited as long as the carbon atom bonded to the oxygen atom bonded to the carbonyl group is a tertiary carbon atom, but has 3 to 8 carbon atoms. Is more preferable, it is more preferable that it is 3-7, and it is further more preferable that it is 3-6.
The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and more specifically, a group represented by -C (R ¹⁸ ) (R ¹⁹ )-(R ²⁰ ) _n-. Is mentioned.
In the formula, R ¹⁸ and R ¹⁹ are each independently an alkyl group which may have a substituent, and R ²⁰ is a linear or branched alkylene group which may have a substituent. And n is 0 or 1.
The alkyl group in R ¹⁸ and R ¹⁹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, n -Butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like can be mentioned.
The linear or branched alkylene group for R ²⁰ preferably has 1 to 10 carbon atoms, more preferably 1 to 8, still more preferably 1 to 5, and particularly preferably 1 or 2.
Specific examples of the linear alkylene group in R ²⁰ include a methylene group, an ethylene group [— (CH ₂ ) ₂ —], a trimethylene group [— (CH ₂ ) ₃ —], and a tetramethylene group [— (CH _{2) 4} -], a pentamethylene group [- _{(CH 2) 5} -], and the like.
Specific examples of the branched alkylene group for R ²⁰ include —CH (CH ₃ ) —, —CH (CH ₂ CH ₃ ) —, —C (CH ₃ ) ₂ —, —C (CH ₃ ) ( _{CH 2 CH 3) -, -} C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - alkyl groups such _{as; -CH (CH 3) CH 2} -, - _{CH (CH 3) CH (CH} 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - CH (CH 2 CH 3) CH 2 -, - C ( Alkylethylene groups such as CH ₂ CH ₃ ) ₂ —CH ₂ —; alkyl trimethylene groups such as —CH (CH ₃ ) CH ₂ CH ₂ — and —CH ₂ CH (CH ₃ ) CH ₂ —; —CH (CH _{3) CH 2 CH 2 CH 2} -, - CH 2 CH (CH 3) CH 2 Examples include alkylalkylene groups such as alkyltetramethylene groups such as CH ₂ —. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.
The branched aliphatic hydrocarbon group for X may or may not have a substituent. The aliphatic hydrocarbon group having a substituent means that part or all of the hydrogen atoms of the aliphatic hydrocarbon group are substituted with a substituent (atom or group other than a hydrogen atom).
Examples of the substituent that the branched aliphatic hydrocarbon group may have include a hydroxyl group, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, and an oxygen atom (═O).

As the “aliphatic hydrocarbon group including a ring in the structure” of X, a cyclic aliphatic hydrocarbon group (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), the cyclic aliphatic hydrocarbon group Includes a group bonded to the terminal of the chain aliphatic hydrocarbon group described above or interposed in the middle of the chain aliphatic hydrocarbon group.
The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. As the monocyclic group, a group in which two hydrogen atoms have been removed from a monocycloalkane having 3 to 6 carbon atoms is preferable, and examples of the monocycloalkane include cyclopentane and cyclohexane.
As the polycyclic group, a group in which two hydrogen atoms are removed from a polycycloalkane having 7 to 12 carbon atoms is preferable. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, tetra And cyclododecane.
The cyclic aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, and an oxygen atom (= O).
When X is an aliphatic hydrocarbon group containing a ring in the structure, specific examples thereof include a general formula (2-1) to (2-3) described later at the oxygen atom-side end bonded to the carbonyl group. And those containing a group represented by any of the above.

In the present invention, X is preferably an unsubstituted alkylene group at the end on the oxygen atom side bonded to R ⁴ among adjacent oxygen atoms.
As X, in particular, —R ² —R ³ — [wherein R ² is a divalent aliphatic hydrocarbon group which may have a substituent, and is a carbon bonded to an adjacent oxygen atom. The atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group. ] Is preferable. That is, the structural unit (a0) is preferably a structural unit represented by the following general formula (a0-1-1).

［式中、Ｒ^１およびＲ^４はそれぞれ前記と同じであり；Ｒ^２は、置換基を有していてもよい２価の脂肪族炭化水素基であって、隣接する酸素原子に結合する炭素原子が第３級炭素原子であり；Ｒ^３は直鎖状または分岐鎖状のアルキレン基である。］

[Wherein, R ¹ and R ⁴ are the same as defined above; R ² is a divalent aliphatic hydrocarbon group which may have a substituent, and is a carbon bonded to an adjacent oxygen atom; The atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group. ]

Examples of R ² include the same aliphatic hydrocarbon groups as those described above for X.
In the present invention, as R ² , one hydrogen atom is removed from the tertiary alkyl ester type acid dissociable dissolution inhibiting group among the acid dissociable dissolution inhibiting groups used in the base resin for chemically amplified resist. The groups are preferred. Examples of the tertiary alkyl ester-type acid dissociable, dissolution inhibiting group include the same groups as those exemplified in the structural unit (a1) described later.
Specific examples of R ² include a group represented by the following general formula (2-1), a group represented by the general formula (2-2), and a group represented by the general formula (2-3). It is done.
R ² is preferably at least one selected from the group consisting of groups represented by any of formulas (2-1) to (2-3), and the group represented by formula (2-1) is Particularly preferred.

［式（２−１）中、Ｒ^２１およびＲ^２２は、それぞれ独立に置換基を有していてもよいアルキル基であり；Ｒ^２３は、２価の脂肪族環式基である。式（２−２）中、Ｒ^２４およびＲ^２５は相互に結合して、Ｒ^２４およびＲ^２５が結合した炭素原子とともに脂肪族環を形成しており；Ｒ^２６は、置換基を有していてもよい直鎖状または分岐鎖状のアルキレン基である。式（２−３）中、Ｒ^２７はアルキル基であり；Ｒ^Ｘは、置換基を有していてもよい脂肪族環式基である。］

[In Formula (2-1), R ²¹ and R ²² are each independently an optionally substituted alkyl group; R ²³ is a divalent aliphatic cyclic group. In Formula (2-2), R ²⁴ and R ²⁵ are bonded to each other to form an aliphatic ring together with the carbon atom to which R ²⁴ and R ²⁵ are bonded; R ²⁶ has a substituent. It may be a linear or branched alkylene group. In Formula (2-3), R ²⁷ is an alkyl group; R ^X is an aliphatic cyclic group that may have a substituent. ]

In formula (2-1), R ²¹ and R ²² are each independently an alkyl group which may have a substituent.
The alkyl group in R ²¹ and R ²² may be linear, branched or cyclic, and is preferably linear or branched.
The linear or branched alkyl group is preferably a lower alkyl group, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group. Group, isopentyl group, neopentyl group and the like. Among these, a methyl group, an ethyl group or an n-butyl group is preferable, a methyl group or an ethyl group is more preferable, and a methyl group is most preferable.
The alkyl group may or may not have a substituent. Examples of the substituent include a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, and an oxygen atom (= O).

R ²³ is a divalent aliphatic cyclic group.
In the present specification and claims, the “aliphatic cyclic group” refers to a monocyclic group or a polycyclic group having no aromaticity.
The aliphatic cyclic group may be either saturated or unsaturated, but is preferably saturated because it is highly transparent to ArF excimer laser and the like, and has excellent resolution and depth of focus (DOF). .
It is preferable that carbon number of an aliphatic cyclic group is 3-15.
The aliphatic cyclic group for R ²³ may be monocyclic, polycyclic, or polycyclic.
The aliphatic cyclic group may be a hydrocarbon group (alicyclic group) composed of carbon and hydrogen, and some of the carbon atoms constituting the ring of the alicyclic group are oxygen atoms, nitrogen atoms, sulfur. It may be a heterocyclic group substituted with a heteroatom such as an atom. As the aliphatic cyclic group, an alicyclic group is preferable.
Specific examples of the monocyclic alicyclic group include groups in which two or more hydrogen atoms have been removed from a monocycloalkane. More specifically, a group in which two or more hydrogen atoms have been removed from cyclopentane or cyclohexane is exemplified, and a group in which two or more hydrogen atoms have been removed from cyclohexane is preferred.
Specific examples of the polycyclic alicyclic group include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these, adamantane, norbornane, and tetracyclododecane are preferable because they are easily available industrially, and adamantane or norbornane is particularly preferable.
The aliphatic cyclic group may or may not have a substituent. Examples of the substituent that the aliphatic cyclic group may have include an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O) and the like.

  Specific examples of the group represented by the formula (2-1) include groups represented by the following general formulas (2-11) to (2-16).

［式中、Ｒ^２１およびＲ^２２はそれぞれ前記と同じである。］

[Wherein, R ²¹ and R ²² are the same as defined above. ]

In formula (2-2), R ²⁴ and R ²⁵ are bonded to each other to form an aliphatic ring together with the carbon atom to which R ²⁴ and R ²⁵ are bonded.
The aliphatic ring may be either saturated or unsaturated, but is preferably saturated because it is highly transparent to ArF excimer laser and the like, and has excellent resolution and depth of focus (DOF).
It is preferable that carbon number of an aliphatic ring is 3-15.
The aliphatic ring may be a hydrocarbon ring composed of carbon and hydrogen, and a part of carbon atoms constituting the ring of the hydrocarbon ring is substituted with a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom. Heterocyclic group etc. may be sufficient. As the aliphatic ring, a hydrocarbon ring is preferable.
The hydrocarbon ring formed together with the carbon atom to which R ²⁴ and R ²⁵ are bonded may be monocyclic or polycyclic.
Specific examples of the monocyclic hydrocarbon ring include a group in which two hydrogen atoms are removed from one carbon atom among the carbon atoms constituting the monocycloalkane. More specifically, a group obtained by removing two hydrogen atoms from one carbon atom of cyclopentane or cyclohexane is preferable, and a group obtained by removing two hydrogen atoms from one carbon atom of cyclohexane is preferable.
As a specific example of the polycyclic alicyclic group, two hydrogen atoms were removed from one carbon atom among carbon atoms constituting a polycycloalkane such as bicycloalkane, tricycloalkane, and tetracycloalkane. Groups. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these, adamantane, norbornane, and tetracyclododecane are preferable because they are easily available industrially, and adamantane or norbornane is particularly preferable.
The aliphatic ring may or may not have a substituent. Examples of the substituent that the aliphatic cyclic group may have include an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O) and the like.

R ²⁶ represents a linear or branched alkylene group which may have a substituent.
As the alkylene group for R ^26, the same as the linear or branched alkylene groups for R ²⁰ can be used. The alkylene group may or may not have a substituent. Examples of the substituent in the alkylene group include a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, and an oxygen atom (═O).

Specific examples of the group represented by the formula (2-2) include groups represented by the following general formulas (2-21) to (2-29).
In formula (2-22), g is preferably an integer of 0 to 5, more preferably an integer of 1 to 3, and even more preferably 1 or 2.

［式中、Ｒ^２６は前記と同じであり、Ｂは酸素原子、硫黄原子、メチレン基またはエチレン基であり、ｇは０〜８の整数である。］

[Wherein, R ²⁶ is the same as defined above, B is an oxygen atom, a sulfur atom, a methylene group or an ethylene group, and g is an integer of 0-8. ]

In formula (2-3), examples of the alkyl group for R ²⁷ include the same alkyl groups as those described above for R ²¹ and R ²² .
R ^X is an aliphatic cyclic group which may have a substituent. As the aliphatic cyclic group, R ²⁴ and R ²⁵ are bonded to each other, and one hydrogen atom is formed from the aliphatic ring mentioned as the aliphatic ring formed together with the carbon atom to which R ²⁴ and R ²⁵ are bonded. Excluded groups are mentioned.
Specific examples of the group represented by the formula (2-3) include groups represented by the following general formulas (2-31) to (2-39).
In the formula (2-32), g is the same as g in the formula (2-22).

［式中、Ｒ^２７は前記と同じであり、Ｂは酸素原子、硫黄原子、メチレン基またはエチレン基であり、ｇは０〜８の整数である。］

[Wherein, R ²⁷ is the same as defined above, B is an oxygen atom, a sulfur atom, a methylene group or an ethylene group, and g is an integer of 0-8. ]

In formula (a0-1-1), R ³ represents a linear or branched alkylene group.
The alkylene group preferably has 1 to 5 carbon atoms in the main chain, more preferably 1 to 4, particularly preferably 1 to 3, and most preferably 1.
Specific examples of the linear alkylene group include a methylene group [—CH ₂ —], an ethylene group [— (CH ₂ ) ₂ —], a trimethylene group [— (CH ₂ ) ₃ —], a tetramethylene group [ — (CH ₂ ) ₄ —], pentamethylene group [— (CH ₂ ) ₅ —] and the like can be mentioned.
Examples of the branched alkylene group include a group in which a linear or branched alkyl group is bonded to the linear alkylene group. The alkyl group is preferably linear. 1-5 are preferable, as for carbon number of this alkyl group, 1-3 are more preferable, and 1 or 2 is further more preferable. Specifically, as the branched alkylene group, —CH (CH ₃ ) —, —CH (CH ₂ CH ₃ ) —, —C (CH ₃ ) ₂ —, —C (CH ₃ ) (CH ₂ CH _{3) -, - C (CH} 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - alkyl groups such _{as; -CH (CH 3) CH 2} -, - CH (CH _{3) CH (CH 3) -} , - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - CH (CH 2 CH 3) CH 2 -, - C (CH 2 CH _{3) 2} -CH ₂ - alkyl groups such _{as; -CH (CH 3) CH 2} CH 2 -, - CH 2 CH (CH 3) CH 2 - alkyl trimethylene groups such as; -CH _(CH 3) CH _{2 CH 2 CH 2 -, -} CH 2 CH (CH 3) CH 2 CH 2 - , etc. It includes alkylalkylene groups such as Le Kill tetramethylene group. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

In formula (a0-1), R ⁴ represents an acetal type acid dissociable, dissolution inhibiting group.
The “acid-dissociable, dissolution-inhibiting group” has an alkali dissolution-inhibiting property that suppresses the solubility of the component (A1) in an alkaline developer before dissociation, and is dissociated by an acid generated from the component (B) upon exposure. (A1) This increases the solubility of the entire component in an alkaline developer.
The acetal type acid dissociable, dissolution inhibiting group for R ⁴ is not particularly limited, and those proposed so far can be used.
Examples of the acetal type acid dissociable, dissolution inhibiting group include groups represented by general formula (p1) shown below.

［式中、Ｙは直鎖状もしくは分岐鎖状のアルキル基または１価の脂肪族環式基であり、ｎは０〜３の整数であり、Ｒ^１’およびＲ^２’はそれぞれ独立して直鎖状もしくは分岐鎖状のアルキル基または水素原子であり、ＹおよびＲ^１’が相互に結合して脂肪族環を形成していてもよい。］

[Wherein Y is a linear or branched alkyl group or a monovalent aliphatic cyclic group, n is an integer of 0 to 3, and R ¹ ′ and R ² ′ are each independently It is a linear or branched alkyl group or a hydrogen atom, and Y and R ¹ ′ may be bonded to each other to form an aliphatic ring. ]

In the above formula (p1), Y represents a linear or branched alkyl group or a monovalent aliphatic cyclic group.
When Y is a linear or branched alkyl group, the carbon number is preferably 1-15, more preferably 1-5, still more preferably an ethyl group or a methyl group, and the ethyl group is Most preferred.
When Y is a monovalent aliphatic cyclic group, the aliphatic cyclic group is appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in large numbers in ArF resists and the like. Can be used. Examples of the aliphatic cyclic group include the same (but monovalent) as the aliphatic cyclic group for R ²³ .
The monovalent aliphatic cyclic group for Y preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specific examples include groups in which one or more hydrogen atoms have been removed from a cycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. The cycloalkane may or may not have a fluorine atom or a fluorinated alkyl group as a substituent.
Specific examples of the aliphatic cyclic group include groups in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane: adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, or the like. And a group obtained by removing one or more hydrogen atoms from cycloalkane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.

In formula (p1), n is an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.
R ¹ ′ and R ² ′ are each independently a linear or branched alkyl group or a hydrogen atom.
The linear or branched alkyl group for R ¹ ′ and R ² ′ is preferably a lower alkyl group. Examples of the lower alkyl group include the same lower alkyl groups as those described above for R ¹ , preferably a methyl group or an ethyl group, and most preferably a methyl group.
In the present invention, it is preferable that at least one of R ¹ ′ and R ² ′ is a hydrogen atom. That is, the group represented by the formula (p1) is preferably a group represented by the following general formula (p1-1).

［式中、Ｒ^１’、ｎ、Ｙはそれぞれ前記と同じである。］

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

In the above formula (p1), Y and R ¹ ′ may be bonded to each other to form an aliphatic ring.
In this case, an aliphatic ring is formed by Y, R ¹ ′, —O— (CH ₂ ) _n —, and the carbon atom to which R ² ′ is bonded. As this aliphatic cyclic group, a 4-7 membered ring is preferable and a 4-6 membered ring is more preferable. Specific examples of the aliphatic cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

Examples of the structural unit represented by the general formula (a0-1-1) include the following.
In each formula, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

  As the structural unit (a0), a structural unit represented by general formula (a0-1-11) shown below is particularly preferred, and a structural unit represented by general formula (a0-1-111) shown below is particularly preferred.

［式中、Ｒ^１、Ｒ^３、Ｒ^４、Ｒ^２１〜Ｒ^２３はそれぞれ前記と同じである。］

[Wherein, R ¹ , R ³ , R ⁴ and R ^{21 to} R ²³ are the same as defined above. ]

［式中、Ｒ^１、Ｒ^２１〜Ｒ^２２およびＲ^１’はそれぞれ前記と同じであり、Ｒ^２１’〜Ｒ^２２ ’はそれぞれ独立に直鎖状または分岐鎖状のアルキル基である。］

[Wherein, R ¹ , R ^{21 to} R ²² and R ¹ ′ are the same as defined above, and R ²¹ ′ to R ²² ′ are each independently a linear or branched alkyl group. ]

In formula (a0-1-111), the linear or branched alkyl group for R ²¹ ′ to R ²² ′ is the same as the linear or branched alkyl group for R ¹ ′. Is mentioned.

In the component (A1), as the structural unit (a0), one type of structural unit may be used alone, or two or more types may be used in combination.
In addition, the component (A1) may be a polymer composed only of the structural unit (a0), and is a copolymer including other structural units (structural units (a1) to (a4) and the like described later). May be.
The proportion of the structural unit (a0) in the component (A1) 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 structural unit ( The proportion of only a0)) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, and more preferably 30 to 60 mol% with respect to all the structural units constituting the component (A1). Is most preferred. 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.
Further, the proportion of the structural unit (a0) in the component (A1) is such that the effect of reducing the occurrence of defects when forming a resist pattern using a positive resist composition containing the component (A1), half exposure (half After exposure to the tone type phase shift mask), the hydrophilicity is improved during PEB, and the contact angle after resist application (before exposure) is improved. On the other hand, it is preferably 10 mol% or more, more preferably 20 mol% or more.

The component (A1) may have a structural unit other than the structural unit (a0) as long as the effects of the present invention are not impaired. The other structural unit is not particularly limited as long as it is a structural unit derived from a compound copolymerizable with a monomer that derives the structural unit (a0) (compound of the fourth aspect of the present invention described later). For example, what has been proposed as a constituent unit of a base resin for a chemically amplified resist is mentioned. Examples of the structural unit include the following structural units (a1) to (a4).
In the present invention, in particular, the component (A1) preferably has a structural unit (a1) in addition to the structural unit (a0).
The component (A1) preferably further has a structural unit (a2) in addition to the structural unit (a0) or in addition to the structural unit (a0) and the structural unit (a1). In addition to these, it is also preferable to have a structural unit (a3).

-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 component (A1) difficult to dissolve in an alkali developer before dissociation, and dissociates with an acid. This increases the solubility of the entire component in an alkaline developer, and those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists 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 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.
Examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a group represented by -C (R ⁷¹ ) (R ⁷² ) (R ⁷³ ). ^Wherein, R 71 ^{to R 73} each independently represents a linear alkyl group of 1 to 5 carbon atoms. The group represented by —C (R ⁷¹ ) (R ⁷² ) (R ⁷³ ) preferably has 4 to 8 carbon atoms, specifically a tert-butyl group or a 2-methyl-2-butyl group. , 2-methyl-2-pentyl group, 3-methyl-3-pentyl group and the like. A tert-butyl group is particularly preferable.

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 lower alkoxy 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-type 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 in the structural unit (a1) include the same groups as those described above for R ⁴ in the structural unit (a0).

  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２価の連結基を示す。］

[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 a divalent linking 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).
Examples of the divalent linking group for Y ² include an alkylene group, a divalent aliphatic cyclic group, and a divalent linking group containing a hetero atom.
When Y ² is an alkylene group, the number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, particularly preferably 1 to 4, and most preferably 1 to 3. preferable.
When Y ² is a divalent aliphatic cyclic group, examples of the aliphatic cyclic group include the same groups as those described above for R ²³ . Y ² is particularly preferably a group in which two or more hydrogen atoms have been removed from cyclopentane, cyclohexane, norbornane, isobornane, adamantane, tricyclodecane or tetracyclododecane.

When Y ² is a divalent linking group containing a hetero atom, examples of the divalent linking group containing a hetero atom include —O—, —C (═O) —O—, —C (═O) —, —O—C (═O) —O—, —C (═O) —NH—, —NH— (H may be substituted with a substituent such as an alkyl group or an acyl group), —S—. , —S (═O) ₂ —, —S (═O) ₂ —O—, “—AO (oxygen atom) —B— (wherein A and B each independently have a substituent) A divalent hydrocarbon group that may be present.) ”And the like.
When Y ² is —NH—, the substituent (alkyl group, acyl group, etc.) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and more preferably 1 to 5 carbon atoms. It is particularly preferred that

When Y ² is “A—O—B”, A and B are each independently a divalent hydrocarbon group which may have a substituent. The hydrocarbon group having “substituent” means that part or all of the hydrogen atoms in the hydrocarbon group are substituted with groups or atoms other than hydrogen atoms.
The hydrocarbon group in A may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. An aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity.
The aliphatic hydrocarbon group for A may be saturated or unsaturated, and is usually preferably saturated.
Specific examples of the aliphatic hydrocarbon group for A include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure.

The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, still more preferably 2 to 5, and most preferably 2.
As the linear aliphatic hydrocarbon group, a linear alkylene group is preferable. Specifically, a methylene group, an ethylene group [— (CH ₂ ) ₂ —], a trimethylene group [— (CH ₂ ) ₃ -], tetramethylene group _{[- (CH 2) 4 -} ], a pentamethylene group _{[- (CH 2) 5 -} ] , and the like.
As the branched aliphatic hydrocarbon group, a branched alkylene group is preferred, and specifically, —CH (CH ₃ ) —, —CH (CH ₂ CH ₃ ) —, —C (CH ₃ ). _{2 -, - C (CH 3} ) (CH 2 CH 3) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as - _{CH (CH 3) CH 2 -} , - CH (CH 3) CH (CH 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - CH (CH 2 Alkylethylene groups such as CH ₃ ) CH ₂ —; alkyltrimethylene groups such as —CH (CH ₃ ) CH ₂ CH ₂ —, —CH ₂ CH (CH ₃ ) CH ₂ —; —CH (CH ₃ ) CH _{2 CH 2 CH 2 -, - CH} 2 CH (CH 3) CH 2 CH 2 - , etc. And alkyl alkylene groups such as Le Kill tetramethylene group. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.
The chain-like aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include 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.

Examples of the aliphatic hydrocarbon group containing the ring include a cyclic aliphatic hydrocarbon group (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), and the cyclic aliphatic hydrocarbon group having the chain structure described above. Examples thereof include a group bonded to the end of the aliphatic hydrocarbon group or interposed in the middle of the chain-like aliphatic hydrocarbon group.
The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. As the monocyclic group, a group in which two hydrogen atoms have been removed from a monocycloalkane having 3 to 6 carbon atoms is preferable, and examples of the monocycloalkane include cyclopentane and cyclohexane.
As the polycyclic group, a group in which two hydrogen atoms are removed from a polycycloalkane having 7 to 12 carbon atoms is preferable. Specific examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, tetra And cyclododecane.
The cyclic aliphatic hydrocarbon group 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.

  A is preferably a linear aliphatic hydrocarbon group, more preferably a linear alkylene group, still more preferably a linear alkylene group having 2 to 5 carbon atoms, and most preferably an ethylene group.

Examples of the hydrocarbon group for B include the same divalent hydrocarbon groups as those described above for A.
B is preferably a linear or branched aliphatic hydrocarbon group, particularly preferably a methylene group or an alkylmethylene group.
The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

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

［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２価の連結基を表し；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。］

[Wherein, 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; n represents an integer of 0 to 3] Y ² represents a divalent linking 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. ]

In the formula, X 'include the same tertiary alkyl ester-type acid dissociable, dissolution inhibiting groups as those described above for X ^{1.
R 1 ', R 2',} n, as the Y, respectively, ^{R 1} in the general formula listed in the description of "acetal-type acid dissociable, dissolution inhibiting group" described above ^{(p1) ', R 2'} , n, Y The same thing is mentioned.
The Y ^2, the same groups as those described above for ^{Y 2} in the general formula (a1-0-2).

Specific examples of the structural units represented by the general formulas (a1-1) to (a1-4) are shown below.
In each formula, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Among the above, the structural unit (a1) is preferably a structural unit represented by the general formula (a1-1) or (a1-3), specifically, (a1-1-1) to (a1-1). -4), using at least one selected from the group consisting of (a1-1-20) to (a1-1-23) and (a1-3-25) to (a1-3-28). preferable.
Furthermore, as the structural unit (a1), those represented by the following general formula (a1-1-01) that include structural units of the formula (a1-1-1) to the formula (a1-1-3), Or the following general formula (a1-1-02) including the structural units of formulas (a1-1-16) to (a1-1-17) and formulas (a1-1-20) to (a1-1-23) The thing represented by these is 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１〜６の整数を表す。）

(In the formula, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹² represents a lower alkyl group. H represents an integer of 1 to 6.)

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.

As the structural unit (a0) contained in the component (A1), 1 type of structural unit may be used, or 2 or more types may be used.
In the component (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) is relative to all structural units constituting the component (A1). The amount of 10 to 80 mol% is preferred, the amount of 20 to 70 mol% is more preferred, and the amount of 30 to 60 mol% is most preferred. 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 component (A1) contains both the structural unit (a0) and the structural unit (a1), the ratio (molar ratio) of each structural unit in the component (A1) is the structural unit (a0): structural unit ( a1) = preferably within the range of 99: 1 to 1:99, more preferably within the range of 80:20 to 20:80, and even more preferably within the range of 70:30 to 30:70.

Structural unit (a2):
The structural unit (a1) is a structural unit derived from an acrylate ester containing a lactone-containing cyclic group.
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 copolymer (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) is improved in the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in improving the sex.
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、炭素数１〜５のアルコキシ基または−ＣＯＯＲ”であり、前記Ｒ”は水素原子、または炭素数１〜１５の直鎖状、分岐鎖状もしくは環状のアルキル基であり、ｍは０または１の整数であり、Ａ”は酸素原子もしくは硫黄原子を含んでいてもよい炭素数１〜５のアルキレン基、酸素原子または硫黄原子である。］

[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, an alkoxy group having 1 to 5 carbon atoms, or —COOR ″, wherein R ″ is A hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms, m is an integer of 0 or 1, and A ″ is a carbon which may contain an oxygen atom or a sulfur atom. It is an alkylene group of formulas 1 to 5, an oxygen atom or a sulfur 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).
When R ″ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ″ is a cyclic alkyl group, it preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, a fluorine atom or fluorine atom A group in which one or more hydrogen atoms are removed from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, etc., which may or may not be substituted with an alkyl group. Specific examples thereof include monocycloalkanes such as cyclopentane and cyclohexane, groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Can be mentioned.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Specific examples of the alkylene group having 1 to 5 carbon atoms that may contain an oxygen atom or sulfur atom of A ″ include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, —O—CH ₂ —. _{, -CH 2 -O-CH 2 -} , - S-CH 2 -, - CH 2 -S-CH 2 - , and the like.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.
In each formula, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

In the component (A1), as the structural unit (a2), one type 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 ( At least one selected from the group consisting of structural units represented by a2-3) is more preferred. Among these, from structural units represented by chemical formulas (a2-1-1), (a2-2-1), (a2-2-7), (a2-3-1) and (a2-3-5) At least one selected from the group consisting of
The proportion of the structural unit (a2) in the component (A1) is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, with respect to the total of all structural units constituting the component (A1). 50 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 component (A1) has the structural unit (a3), the hydrophilicity of the component (A1) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. Contributes to improvement.
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.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
When the structural unit (a3) is contained in the component (A1), the proportion of the structural unit (a3) in the component (A1) is 5 to 50 mol% with respect to all the structural units constituting the component (A1). It is preferable that it is 5 to 40 mol%, more preferably 5 to 25 mol%.

-Structural unit (a4):
The structural unit (a4) is a structural unit other than the structural units (a0) to (a3).
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a0) to (a3) described above. 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 the structural unit (a4) is contained in the component (A1), the proportion of the structural unit (a4) in the component (A1) is 1 to 30 with respect to the total of all the structural units constituting the component (A1). Mol% is preferable and 10 to 20 mol% is more preferable.

  The component (A1) is preferably a copolymer having the structural units (a0) and (a2). Examples of the copolymer include a copolymer composed of the structural units (a0) and (a2), a copolymer composed of the structural units (a0), (a1) and (a2), a structural unit (a0), Examples thereof include a copolymer comprising (a1), (a2) and (a3).

The mass average molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of the component (A1) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 20000. Most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When 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) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

As the component (A1), a monomer that derives each structural unit (for example, a compound (I) described later, and a monomer that derives another structural unit as necessary), such as azobisisobutyronitrile (AIBN), is used. It can obtain by making it superpose | polymerize by well-known radical polymerization etc. which used the radical polymerization initiator.
Further, for the component (A1), in the polymerization, a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination, so that the terminal A —C (CF ₃ ) ₂ —OH group may be introduced into the. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of the 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 in reducing

In the component (A), as the component (A1), one type may be used alone, or two or more types may be used in combination.
The proportion of the component (A1) in the component (A) is preferably 10% by mass or more, more preferably 30% by mass, further preferably 50% by mass, and 100% by mass with respect to the total mass of the component (A). May be. When the ratio is 10% by mass or more, effects such as reduction of defects are improved.

In the resist composition of the present invention, as the component (A), a base material component (hereinafter referred to as the component (A2)) that does not correspond to the component (A1) and whose solubility in an alkaline developer is increased by the action of an acid. You may contain.
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 ArF) A base resin such as for excimer laser) may be arbitrarily selected and used. For example, the base resin for ArF excimer laser includes a resin 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.

  In the resist composition of the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

<(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、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 together to form a ring with the sulfur atom in the formula; R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group; R ¹ At least one of “˜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 those described above for R ¹ ″ to R ³ ″.

R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
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.

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 the 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 a heteroaryl group in which a part of carbon atoms constituting the ring of these groups is substituted with a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. 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 of 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.

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, it is preferable to use an onium salt acid generator having a fluorinated alkyl sulfonate ion as an anion as the component (B).
The content of the component (B) in the positive resist composition of the present invention is preferably 0.5 to 50 parts by mass and more preferably 1 to 40 parts by mass with respect to 100 parts by mass of the component (A). 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>
The positive resist composition of the present invention may further contain a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component.
The component (D) is not particularly limited as long as it acts as an acid diffusion controller, that is, a quencher that traps the acid generated from the component (B) by exposure, and a wide variety of components have already been proposed. Therefore, any known one may be used, and aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are particularly preferable. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 20 carbon atoms.
Examples of the aliphatic amine include an amine (alkylamine 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 20 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 amine, tri -n- octanol amine, stearyl diethanolamine, alkyl alcohol amines such as lauryl diethanolamine. Among these, trialkylamine and / or alkyl alcohol amine are 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.
Examples of the aromatic amine include aniline, pyridine, 4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole or derivatives thereof, diphenylamine, triphenylamine, and tribenzylamine.
Other aliphatic amines include tris (2-methoxymethoxyethyl) amine, tris {2- (2-methoxyethoxy) ethyl} amine, tris {2- (2-methoxyethoxymethoxy) ethyl} amine, tris {2 -(1-methoxyethoxy) ethyl} amine, tris {2- (1-ethoxyethoxy) ethyl} amine, tris {2- (1-ethoxypropoxy) ethyl} amine, tris [2- {2- (2-hydroxy Ethoxy) ethoxy} ethylamine 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. By setting the content in the above range, the resist pattern shape, the stability over time, and the like are improved.

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, retention 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.
(E) A 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 further contains miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, dissolution inhibitors, Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added and contained as appropriate.

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.
Among these, 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 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. -20% by mass, preferably 2-15% by mass.

≪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 developing 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 of the present invention is applied onto a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds under a temperature condition of 80 to 150 ° C., preferably For 60 to 90 seconds, using an exposure apparatus such as an ArF exposure apparatus, an electron beam drawing apparatus, or an EUV exposure apparatus, exposure through a mask pattern, or drawing by direct irradiation of an electron beam without using a mask pattern, etc. Then, PEB (post-exposure heating) is applied for 40 to 120 seconds, preferably 60 to 90 seconds, at a temperature of 80 to 150 ° C. Subsequently, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide (TMAH), 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. The resist composition is effective for KrF excimer laser, ArF excimer laser, EB or EUV, particularly ArF excimer laser.
The exposure of the resist film may be normal exposure (dry exposure) performed in an inert gas such as air or nitrogen, or may be immersion exposure.

≪Polymer compound≫
The polymer compound of the present invention is a polymer compound having the structural unit (a0) represented by the general formula (a0-1).
The description of the polymer compound of the present invention is the same as the description of the component (A1) of the positive resist composition of the present invention.
As described above, the polymer compound (A1) is a monomer derived from the target structural unit, such as azobisisobutyronitrile (AIBN), dimethyl-2,2′-azobis (2-methylpropionate). It can obtain by making it superpose | polymerize by well-known radical polymerization etc. using such a radical polymerization initiator.
For example, the monomer of the structural unit (a0) includes the following compounds of the present invention.

≪Compound≫
The compound of the present invention is a compound represented by the following general formula (I) (hereinafter referred to as compound (I)).

In formula (I), R ¹ , X, and R ⁴ are the same as R ¹ , X, and R ^{4 in} formula (a0-1), respectively.

The production method of compound (I) is not particularly limited, and can be produced using a conventionally known method.
For example, a compound represented by the following general formula (I-1) (hereinafter referred to as compound (I-1)) and a compound represented by the following general formula (I-2) (hereinafter referred to as compound (I-2) The compound (I) can be produced by reacting with the above.

［式中、Ｒ^１、Ｘ、Ｒ^４は、それぞれ前記と同じであり、Ｘ^１１はハロゲン原子である。］

[Wherein, R ¹ , X and R ⁴ are the same as defined above, and X ¹¹ is a halogen atom. ]

^R 1, X, ^{R 4} in the formula (I-1) ~ (I -2) , respectively, ^R 1, X in Formula (I), the same as ^{R 4.}
Examples of the halogen atom in X ¹¹ include a bromine atom, a chlorine atom, an iodine atom, and a fluorine atom. Among these, a chlorine atom and a bromine atom are preferable because of excellent reactivity.
As compound (I-1) and compound (I-2), commercially available compounds may be used, respectively, or they may be synthesized by a known method. For example, compound (I-1) can be produced using a general method for producing an acrylate ester. For example, the manufacturing method of Unexamined-Japanese-Patent No. 2006-16379 can be used.

The method for reacting compound (I-1) and compound (I-2) is not particularly limited. For example, in a solution in which compound (I-1) is dissolved in a reaction solvent, in the presence of a base, The method of adding compound (I-2) is mentioned.
Any reaction solvent may be used as long as it can dissolve the starting compounds (I-1) and (I-2). Specifically, tetrahydrofuran (THF), acetone, dimethylformamide (DMF), dimethylacetamide , Dimethyl sulfoxide (DMSO), acetonitrile and the like.
Examples of the base include inorganic bases such as sodium hydride and K ₂ CO ₃ ; organic bases such as diisopropylethylamine, triethylamine, 4-dimethylaminopyridine (DMAP) and pyridine.
The amount of compound (I-2) added is preferably about 1 to 2 mol times, more preferably 1 to 1.5 mol times relative to compound (I-1).
The reaction temperature is preferably 0 to 50 ° C, more preferably 5 to 40 ° C, and most preferably a reaction at room temperature.
The reaction time varies depending on the reactivity of the compounds (I-1) and (I-2), the reaction temperature, and the like, but is usually preferably 1 to 24 hours, more preferably 3 to 12 hours.
After completion of the reaction, the compound (I) in the reaction solution may be isolated and purified. For isolation and purification, conventionally known methods can be used. For example, concentration, solvent extraction, crystallization, recrystallization, chromatography and the like can be used alone or in combination of two or more.
The structure of the compound obtained in the above step is as follows: ¹ H-nuclear magnetic resonance (NMR) spectrum method, ¹³ C-NMR spectrum method, ¹⁹ F-NMR spectrum method, infrared absorption (IR) spectrum method, mass spectrometry (MS) method. It can be confirmed by general organic analysis methods such as elemental analysis and X-ray crystal diffraction.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
[Synthesis Example 1 (Synthesis of Compound 3)]
In a 1000 ml three-necked flask, under nitrogen atmosphere, 40 g of [Compound 1] and 800 ml of tetrahydrofuran (THF) are added and dissolved, and 53.4 g of diisopropylethylamine (EtiPr ₂ N) is added with stirring at room temperature, and then cooled to 0 ° C. Then, 62.6 g of [Compound 2] (2-adamantoxymethyl chloride) was added and reacted at room temperature for 10 hours. Then, water was added to stop the reaction, the reaction solution was filtered, the reaction solvent was concentrated under reduced pressure, and the organic layer obtained by extraction with ethyl acetate was washed with water. The product obtained by distilling off the solvent under reduced pressure was purified on a silica gel column, and the disappearance of the raw material was confirmed by thin layer chromatography (TLC). The product obtained by distilling off the solvent under reduced pressure was dried to obtain [Compound 3].

The structure of the product was confirmed by NMR.
¹ H-NMR data (solvent: CDCl ₃ , 400 MHz, internal standard: tetramethylsilane): δ (ppm) = 6.03 (s, 1H, H ^a ), 5.45 (s, 1H, H ^b ), 4.81 (s, 2H, H ^c ), 3.73 (s, 1H, H ^d ), 1.92 (s, 3H, H ^e ), 1.52 (s, 6H, H ^f ), 1. ^{16 (s, 6H, H g} ), 1.45-2.15 (m, 28H, Admantane).
From the results, it was confirmed that [Compound 3] had the following structure.

[Synthesis Example 2 (Synthesis of Polymer Compound 1)]
In a three-necked flask connected with a thermometer and a reflux tube, 6.25 g (36.75 mmol) of the following [Compound 4], 20.04 g (41.34 mmol) of the following [Compound 3], 4.34 g (18. 37 mmol) of [Compound 5] was added and dissolved in 45.95 g of tetrahydrofuran (THF). To this solution, 5.79 mmol of dimethyl azobisisobutyrate (V-601) was added as a radical polymerization initiator and dissolved. The resultant was dropwise added to 25.52 g of THF heated to 65 ° 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. The obtained reaction polymerization liquid is dropped into a large amount of methanol / water mixed solvent, and an operation for precipitating the reaction product (copolymer) is performed. The precipitated reaction product is filtered, washed and dried, 21.51 g of [Polymer Compound 1] was obtained.
With respect to [Polymer Compound 1], the mass average molecular weight (Mw) in terms of standard polystyrene determined by GPC measurement was 32,500, and the molecular weight dispersity (Mw / Mn) was 1.64.
The copolymer composition ratio (ratio of each structural unit in the following structural formula (molar ratio)) determined by carbon 13 nuclear magnetic resonance spectrum (600 MHz — ¹³ C-NMR) at 600 MHz is 1 / m / n = It was 43.6 / 34.6 / 21.8.

[Synthesis Example 3 (Synthesis of Polymer Compound 2)]
In a three-necked flask connected with a thermometer and a reflux tube, 6.75 g (39.73 mmol) of the following [Compound 4], 9.76 g (41.72 mmol) of the following [Compound 6], 13.00 g (26. 82 mmol) of the following [Compound 3] was added and dissolved in 44.27 g of THF. To this solution, 27.07 mmol of dimethyl azobisisobutyrate (V-601) as a radical polymerization initiator was added and dissolved. The resultant was dropwise added to 24.59 g of THF heated to 65 ° 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. The obtained reaction polymerization liquid is dropped into a large amount of methanol / water mixed solvent, and an operation for precipitating the reaction product (copolymer) is performed. The precipitated reaction product is filtered, washed and dried, 23.67 g of [Polymer Compound 2] was obtained.
For this [polymer compound 2], the mass average molecular weight (Mw) in terms of standard polystyrene determined by GPC measurement was 10,400, and the molecular weight dispersity (Mw / Mn) was 1.59.
The copolymer composition ratio (ratio of each structural unit in the following structural formula (molar ratio)) determined by carbon 13 nuclear magnetic resonance spectrum (600 MHz — ¹³ C-NMR) at 600 MHz is 1 / m / n = It was 40.6 / 34.7 / 24.7.

[Synthesis Example 4 (Synthesis of Polymer Compound 3)]
In a three-necked flask connected with a thermometer and a reflux tube, 5.20 g (30.56 mmol) of the following [Compound 4], 12.01 g (45.84 mmol) of the following [Compound 7], 10.00 g (20. 63 mmol) of the following [Compound 3] was added, and 1.80 g (7.64 mmol) of the following [Compound 5] was dissolved in 43.52 g of THF. To this solution, 12.56 mmol of dimethyl azobisisobutyrate (V-601) was added as a radical polymerization initiator and dissolved. The resultant was dropwise added to 24.17 g of THF heated to 65 ° 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. The obtained reaction polymerization liquid is dropped into a large amount of methanol / water mixed solvent, and an operation for precipitating the reaction product (copolymer) is performed. The precipitated reaction product is filtered, washed and dried, 24.17 g of [Polymer Compound 3] was obtained.
With respect to this [polymer compound 2], the mass average molecular weight (Mw) in terms of standard polystyrene determined by GPC measurement was 11,800, and the molecular weight dispersity (Mw / Mn) was 1.53.
The copolymer composition ratio (ratio (molar ratio) of each structural unit in the following structural formula) determined by carbon 13 nuclear magnetic resonance spectrum (600 MHz — ¹³ C-NMR) at 600 MHz is 1 / m / n / o = 35.3 / 32.0 / 21.5 / 11.2.

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

In Table 1, the numerical values in [] indicate the blending amount (parts by mass). Moreover, the symbol in Table 1 shows the following, respectively.
(A) -2: The polymer compound 2.
(A) -3: The polymer compound 3.
(A) -4: The following chemical formula (A) -4 [wherein l / m / n = 45/35/20 (molar ratio)] Mw = 7000 and Mw / Mn = 1.8 Polymer].
(A) -5: The following chemical formula (A) -5 synthesized with reference to JP-A-2006-16379 [0061] [wherein 1 / m / n = 40/35/25 (molar ratio)] Copolymer of Mw = 10000 and Mw / Mn = 1.6 represented by
(B) -1: Triphenylsulfonium nonafluoro-n-butanesulfonate (D) -1: Tri-n-pentylamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.
(S) -2: γ-butyrolactone.

[Measurement of contact angle between exposed and unexposed areas]
The resist compositions of Examples 1 and 2 and Comparative Examples 1 and 2 were each applied onto an 8-inch silicon wafer subjected to hexamethyldisilazane (HMDS) treatment using a spinner, and 110 ° C. on a hot plate. A resist film having a thickness of 100 nm was formed by pre-baking for 60 seconds and drying.
Water (2 μL) is dropped onto the surface of the resist film (resist film before exposure), and the static contact angle and receding angle are measured using DROP MASTER-700 (product name, manufactured by Kyowa Interface Science Co., Ltd.). went. The measured values were defined as “contact angle (after application)” and “retraction angle (after application)” in the unexposed area, respectively. The results are shown in Table 2.
An ArF excimer laser (193 nm) was applied to each wafer after contact angle and receding angle measurement using an ArF exposure apparatus NSR-S302 (Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). And open frame exposure (entire exposure, exposure amount ² mJ / cm ² ). Then, the static contact angle and receding angle of the resist film after the PEB treatment at 100 ° C. for 60 seconds were measured in the same manner as described above. The measured values were taken as “contact angle (after PEB)” and “backward angle (after PEB)” of the exposed part, respectively. The results are shown in Table 2.
Further, the static contact angle and the receding angle of the resist film were measured in the same manner as described above when only PEB was performed at 100 ° C. for 60 seconds without performing the open frame exposure. The measured values were defined as “contact angle (after PEB)” and “backward angle (after PEB)” of the unexposed area, respectively. The results are shown in Table 2.
Here, the “exposed portion” is an experiment assuming an unexposed portion when a 6% transmission type halftone phase shift mask is used and exposure is performed at an exposure amount of 30 mJ / cm ² . That is, using the 6% transmission of the halftone phase shift mask, assuming 30 mJ / cm ² as an exposure amount, exposure amount irradiated to the unexposed portions of the resist film is about 2 mJ / cm ² .

From the above results, it was confirmed that the resist composition of the present invention has improved hydrophilicity even with an exposure amount of only ² mJ / cm ² . That is, when a halftone mask is used, the hydrophilicity is greatly improved because it decomposes with respect to the light irradiated to the unexposed portion and generates a hydroxyl group. Therefore, according to the resist composition of the present invention, the risk of defects can be reduced. In addition, the contact angle after resist application (before exposure) can be improved, the hydrophilicity after exposure PEB can be improved, and the difference in contact angle before and after exposure PEB can be increased.

[Resolution]
An organic antireflection film composition “ARC29” (trade name, manufactured by Brewer Science Co., Ltd.) 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. Thus, an organic antireflection film having a film thickness of 82 nm was formed. Then, the positive resist compositions of Examples 1 and 2 and Comparative Examples 1 and 2 obtained above were respectively applied on the antireflection film using a spinner, and 100 ° C. for 60 seconds on a hot plate. A pre-bake (PAB) treatment was performed under the conditions described above and dried to form a resist film having a thickness of 100 nm.
Next, an ArF excimer laser (193 nm) is applied to the resist film through a mask pattern using an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, 2/3 annular illumination). Selectively irradiated.
Then, PEB treatment is performed at 100 ° C. for 60 seconds, and further, alkali development is performed with a 2.38 mass% TMAH aqueous solution at 23 ° C. for 30 seconds, and then rinsed with pure water for 30 seconds and shaken off. Drying was performed.
As a result, in each example, a line-and-space resist pattern having a line width of 130 nm and a pitch of 260 nm was formed on the resist film.

  From the above results, it was confirmed that the resist composition of the present invention also has good lithography properties.

Claims (15)

A positive resist composition comprising 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 exposure,
The positive resist composition, wherein the substrate component (A) contains a polymer compound (A1) having a structural unit (a0) represented by the following general formula (a0-1 -1 ).

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ] The positive resist composition according to claim 1 , wherein R ² is a group represented by the following general formula (2-1).

[In Formula (2-1), R ²¹ and R ²² are each independently an optionally substituted alkyl group; R ²³ is a divalent aliphatic cyclic group. ] Wherein R ⁴ is The positive resist composition according to claim 1 or 2, a group represented by the following general formula (p1).

[Wherein Y is a linear or branched alkyl group or a monovalent aliphatic cyclic group, n is an integer of 0 to 3, and R ¹ ′ and R ² ′ are each independently It is a linear or branched alkyl group or a hydrogen atom, and Y and R ¹ ′ may be bonded to each other to form an aliphatic ring. ] The polymer compound (A1), further, does not correspond to the of the structural units (a0), one of the claims 1-3 having a structural unit derived from an acrylate ester (a1) containing an acid dissociable, dissolution inhibiting group A positive resist composition according to claim 1. The positive resist composition according to any one of claims 1 to 4 , wherein the polymer compound (A1) further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group. . Furthermore, the positive resist composition as described in any one of Claims 1-5 containing a nitrogen-containing organic compound component (D). A step of forming a resist film using the positive resist composition according to any one of claims 1 to 6 , a step of exposing the resist film, and an alkali development of the resist film on a support A resist pattern forming method including a step of forming a resist pattern. The high molecular compound which has a structural unit (a0) represented by the following general formula (a0-1 < -1 >).

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ] The polymer compound according to claim 8 , wherein R ² is a group represented by the following general formula (2-1).

[In Formula (2-1), R ²¹ and R ²² are each independently an optionally substituted alkyl group; R ²³ is a divalent aliphatic cyclic group. ] The polymer compound according to claim 8 or 9 , wherein R ⁴ is a group represented by the following general formula (p1).

[Wherein Y is a linear or branched alkyl group or a monovalent aliphatic cyclic group, n is an integer of 0 to 3, and R ¹ ′ and R ² ′ are each independently It is a linear or branched alkyl group or a hydrogen atom, and Y and R ¹ ′ may be bonded to each other to form an aliphatic ring. ] Furthermore, does not correspond to the of the structural units (a0), the polymer compound according to any one of claims 8 to 10 having a structural unit derived from an acrylate ester (a1) containing an acid dissociable, dissolution inhibiting group . Further, the polymer compound according to any one of claims 8-11 having a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group. The compound represented by the following general formula (I <-1> ).

[Wherein, 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 ² is a divalent aliphatic group which may have a substituent. A hydrocarbon group, wherein the carbon atom bonded to the adjacent oxygen atom is a tertiary carbon atom; R ³ is a linear or branched alkylene group ; R ⁴ is an acetal-type acid dissociable solution Inhibiting group. ] The compound according to claim 13 , wherein R ² is a group represented by the following general formula (2-1).

[In Formula (2-1), R ²¹ and R ²² are each independently an optionally substituted alkyl group; R ²³ is a divalent aliphatic cyclic group. ] The compound according to claim 13 or 14 , wherein R ⁴ is a group represented by the following general formula (p1).

[Wherein Y is a linear or branched alkyl group or a monovalent aliphatic cyclic group, n is an integer of 0 to 3, and R ¹ ′ and R ² ′ are each independently It is a linear or branched alkyl group or a hydrogen atom, and Y and R ¹ ′ may be bonded to each other to form an aliphatic ring. ]