JP2008145667A - Positive resist composition for liquid immersion exposure and method of forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition for liquid immersion exposure that can form a resist film having a high surface hydrophobicity and excelling in lithography performance, and a method of forming a resist pattern. <P>SOLUTION: The positive resist composition for liquid immersion exposure comprises (A) resin component whose alkali solubility is increased by the action of an acid; (B) acid generator component capable of generating an acid when exposed to light; and (C) resin component containing a fluorine atom but not having any acid dissociative group, wherein the resin component (A) contains (A1) resin having (a) constituent unit derived from acrylic acid but not containing a fluorine atom, and wherein the resin component (C) contains (C1) noncircular-principal chain resin and (C2) circular-principal-chain resin. The method of forming a resist pattern includes a step of forming a resist film on a support using the resist composition; a step of subjecting the resist film to liquid immersion exposure; and a step of forming a resist pattern by developing the resist film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positive resist composition for liquid immersion exposure and a method for forming a resist pattern, which are used for liquid immersion lithography.

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 radiation 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.
Along with the miniaturization of semiconductor elements, the wavelength of an exposure light source has been shortened and the projection lens has a high numerical aperture (high NA). A machine has been developed. Along with the shortening of the wavelength of the exposure light source, the resist material is required to be improved in lithography characteristics such as sensitivity to the exposure light source and resolution capable of reproducing a pattern with a fine dimension. As a resist material satisfying such requirements, a chemically amplified resist containing a base resin whose alkali solubility is changed by the action of an acid and an acid generator that generates an acid upon exposure is used.
Currently, as a base resin for a chemically amplified resist used in ArF excimer laser lithography and the like, a resin having a structural unit derived from a (meth) acrylate ester in the main chain because of its excellent transparency near 193 nm ( Acrylic resin) is generally used. 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.

As one of the methods for further improving the resolution, exposure (immersion exposure) is performed by interposing a liquid (immersion medium) having a higher refractive index than air between the objective lens of the exposure machine and the sample. A so-called immersion lithography (hereinafter referred to as “immersion exposure”) is known (for example, see Non-Patent Document 1).
According to immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the depth of focus can be reduced. It is said that there is no decline. Moreover, immersion exposure can be performed using an existing exposure apparatus. For this reason, immersion exposure is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Immersion exposure is effective in forming all pattern shapes, and can be combined with super-resolution techniques such as the phase shift method and the modified illumination method that are currently being studied. Currently, as an immersion exposure technique, a technique mainly using an ArF excimer laser as a light source is being actively researched. Currently, water is mainly studied as an immersion medium.

In recent years, with respect to fluorine-containing compounds, their water repellency, transparency and other characteristics have attracted attention, and research and development in various fields has been actively conducted. For example, in the field of resist materials, acid instability such as a methoxymethyl group, tert-butyl group, tert-butyloxycarbonyl group, etc. is added to a fluorine-containing polymer compound for use as a base resin of a positive chemically amplified resist. Introducing groups. However, when such a fluorine-based polymer compound is used as a base resin of a positive resist composition, there are disadvantages such as generation of a large amount of outgas after exposure and insufficient resistance to dry etching gas (etching resistance).
Recently, a fluorine-containing polymer compound having an acid labile group containing a cyclic hydrocarbon group has been reported as a fluorine-containing polymer compound having excellent etching resistance (see, for example, Non-Patent Document 2).
Proceedings of SPIE, 5754, 119-128 (2005). Proceedings of SPIE-The International Society for Optical Engineering (2002), 4690, 76-83.

In immersion exposure, in addition to normal lithography characteristics (sensitivity, resolution, etching resistance, etc.), a resist material having characteristics corresponding to the immersion exposure technique is required.
As a specific example, when the immersion medium is water and the immersion exposure is performed using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium is a lens. Water tracking is required to follow the movement of the water. If the water followability is low, the exposure speed is lowered, and there is a concern that the productivity is affected.
In addition, since the immersion medium comes into contact with the resist film and the lens during immersion exposure, the resist film changes in quality due to elution of the substance contained in the resist into the immersion medium, and the performance is degraded or eluted. It is conceivable that the refractive index of the immersion medium is locally changed by the substance, or the eluted substance contaminates the lens surface to adversely affect the lithography characteristics. That is, problems such as deterioration in sensitivity, a resulting resist pattern having a T-top shape, and surface roughness and swelling of the resist pattern are expected.

Such problems such as water follow-up and substance elution can be solved by increasing the hydrophobicity of the resist film (hydrophobing). For example, there is a tendency that, for example, a decrease in resolution and sensitivity, an increase in the amount of scum, and the like occur.
Thus, in immersion exposure, the development of materials having moderate hydrophobicity becomes an important issue.
However, there are currently few known materials that satisfy both lithography characteristics and characteristics required for immersion exposure.
The present invention has been made in view of the above circumstances, and provides a positive resist composition for immersion exposure and a method for forming a resist pattern, which can form a resist film with high hydrophobicity on the film surface and good lithography characteristics. The purpose is to provide.

  A first aspect of the present invention that solves the above-mentioned problems contains a resin component (A) whose alkali solubility is increased by the action of an acid, an acid generator component (B) that generates an acid upon exposure, and a fluorine atom. And a positive resist composition for immersion exposure containing a resin component (C) having no acid-dissociable group, wherein the resin component (A) comprises a structural unit (a) derived from acrylic acid. The resin component (C1) contains a non-main chain cyclic resin (C1) and a main chain cyclic resin (C2). A positive resist composition for immersion exposure.

  The second aspect of the present invention includes a step of forming a resist film on a support using the positive resist composition for immersion exposure according to the first aspect of the present invention, and the resist film is subjected to immersion exposure. A resist pattern forming method including a step and a step of developing the resist film to form a resist pattern.

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

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition for immersion exposure and a resist pattern forming method capable of forming a resist film having excellent hydrophobicity on the film surface and lithography characteristics.

Hereinafter, the present invention will be described in more detail.
≪Positive resist composition for immersion exposure≫
The positive resist composition for immersion exposure of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter referred to as component (A)), and an acid generator component which generates an acid upon exposure. (B) (hereinafter referred to as component (B)) and a resin component (C) containing a fluorine atom and having no acid-dissociable group (hereinafter referred to as component (C)).
In such a positive resist composition, the component (A) is insoluble in alkali before exposure, and when acid is generated from the component (B) by exposure, the acid increases alkali solubility of the component (A). Therefore, in the formation of a resist pattern, when selective exposure is performed on a resist film obtained using the positive resist composition, the exposed portion turns alkali-soluble while the unexposed portion remains alkali-insoluble. Therefore, a resist pattern can be formed by performing alkali development.

[Resin (A1)]
The resin (A1) has a structural unit (a) derived from acrylic acid and does not contain a fluorine atom. If it is such, it will not specifically limit as resin (A1), Until now, it is possible to use 1 type, or 2 or more types of resin proposed as a base resin for chemically amplified positive resists. it can.

[Structural unit (a)]
In the resin (A1), the structural unit (a) derived from acrylic acid does not contain a fluorine atom.
Here, in the present specification and claims, the “structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid. The term “acrylic acid” includes a narrowly defined acrylic acid (CH ₂ ═CHCOOH) and a derivative in which part or all of the hydrogen atoms are substituted with other groups or atoms.
Derivatives of acrylic acid include, for example, α-substituted acrylic acid in which a substituent (atom or group other than a hydrogen atom) is bonded to the α-position carbon atom of narrowly defined acrylic acid, or hydrogen of the carboxy group of these acrylic acids Acrylic esters in which atoms are substituted with organic groups.
The “organic group” is a group containing a carbon atom, and the organic group in the acrylate ester is not particularly limited. For example, in the structural units listed in the structural units (a1) to (a4) described later, acrylic acid And groups bonded to the ester side chain of the ester (acid dissociable, dissolution inhibiting group, lactone-containing cyclic group, polar group-containing aliphatic hydrocarbon group, polycyclic aliphatic hydrocarbon group, etc.).
The α-position (α-position carbon atom) of acrylic acid is a carbon atom to which a carbonyl group is bonded, unless otherwise specified.
Examples of the substituent of the α-substituted acrylic acid include a lower alkyl group, a halogenated lower alkyl group (however, the structural unit (a) excludes a fluorinated lower alkyl group).
In the structural unit (a), as the lower alkyl group as the substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl And a lower linear or branched alkyl group such as a group, an isopentyl group and a neopentyl group.
As the halogenated lower alkyl group as a substituent at the α-position, part or all of the hydrogen atoms of the lower alkyl group are substituted with halogen atoms other than fluorine atoms, for example, chlorine atoms, bromine atoms, iodine atoms, etc. Groups.

In the structural unit (a), the α-position of acrylic acid is preferably a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group), A hydrogen atom or a lower alkyl group is more preferable, and a hydrogen atom or a methyl group is most preferable from the viewpoint of industrial availability.
More specifically, examples of the structural unit (a) include structural units represented by the following general formula (a).

［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（ただしフッ素化低級アルキル基を除く。）であり、Ｘは水素原子であるか、またはフッ素原子を含まない１価の有機基である。］

[Wherein, R is a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group), and X is a hydrogen atom or a monovalent group that does not contain a fluorine atom. Organic group. ]

The lower alkyl group or halogenated lower alkyl group of R (excluding the fluorinated lower alkyl group) is the lower alkyl group or halogenated lower alkyl group as the substituent at the α-position (excluding the fluorinated lower alkyl group). )).
Examples of the organic group for X include those similar to the above-mentioned “organic group in acrylic ester”.

The resin (A1) preferably contains the structural unit (a) in a proportion of 50 to 100 mol%, and preferably 70 to 100 mol% with respect to the total of all the structural units constituting the resin (A1). It is more preferable. In particular, since the effect of the present invention is particularly excellent, the resin (A1) is preferably composed only of the structural unit (a) derived from acrylic acid.
Here, “consisting only of the structural unit (a)” means that the main chain of the resin (A1) is composed of only the structural unit (a) and does not include other structural units.

・ Structural unit (a1)
In the present invention, the resin (A1) preferably has a structural unit (a1) that does not have a fluorine atom and is derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
Here, in the present specification and claims, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire resin (A1) insoluble in alkali before dissociation, and changes the entire resin (A1) to alkali soluble after dissociation. If it is a thing, the thing proposed so far as an acid dissociable, dissolution inhibiting group of the base resin for chemically amplified resists can be used. Such an acid dissociable, dissolution inhibiting group is generally 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 dissociation property such as an alkoxyalkyl group Dissolution-inhibiting groups are widely known. The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

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

The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a halogen atom other than a fluorine atom, a halogenated lower alkyl group having 1 to 5 carbon atoms substituted with a halogen atom other than a fluorine atom, and an oxygen atom (= O). , Etc.
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.
Specific examples of the aliphatic cyclic group may or may not be substituted with, for example, a lower alkyl group, a halogen atom other than a fluorine atom, or a halogenated alkyl group (excluding a fluorinated alkyl group). Examples thereof include a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
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 a structural unit represented by the following general formula (a1 ″), an aliphatic cyclic group such as an adamantyl group, such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—); And a group having a branched alkylene group having a tertiary carbon atom bonded thereto.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６はアルキル基（直鎖、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 is the same as described above, and R ¹⁵ and R ¹⁶ represent an alkyl group (which may be linear or branched, and preferably has 1 to 5 carbon atoms). ]

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 include a group represented by the following general formula (p1).

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

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

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

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

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

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

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

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

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

［式中、Ｒは水素原子、低級アルキル基、またはハロゲン化低級アルキル基（ただしフッ素化低級アルキル基を除く。）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 (excluding a fluorinated lower alkyl group); 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（ただしフッ素化低級アルキル基を除く。）を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。］

[Wherein, R represents a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group); X ² represents an acid dissociable, dissolution inhibiting group; Y ² represents an alkylene group; Or an aliphatic cyclic group is shown. ]

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. A tertiary alkyl ester type acid dissociable, dissolution inhibiting group is preferred.

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

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

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

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; M represents 0 or 1; 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. ]

At least one of R ¹ ′ and R ² ′ is preferably a hydrogen atom, more preferably a hydrogen atom. n is preferably 0 or 1.

X ′ is the same as the tertiary alkyl ester type acid dissociable, dissolution inhibiting group exemplified in X ¹ above.
Examples of the aliphatic cyclic group for Y include the same groups as those exemplified above in the description of “aliphatic cyclic group”.

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

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
The structural unit (a1) is preferably a structural unit represented by the general formula (a1-1), and includes the following general formulas including the structural units of the formulas (a1-1-1) to (a1-1-4). Represented by (a1-1-01) and represented by the following general formula (a1-1-02) including the structural units of formulas (a1-1-35) to (a1-1-41). Those are more preferred. Among these, those represented by the general formula (a1-1-01) are particularly preferable, and specifically, at least selected from structural units represented by (a1-1-1) to (a1-1-4). It is particularly preferable to use one type.

［式中、Ｒは上記と同様であり、Ｒ^１１は低級アルキル基を示す。］

[Wherein, R is the same as defined above, and R ¹¹ represents a lower alkyl group. ]

［式中、Ｒは上記と同様であり、Ｒ^１２は低級アルキル基を示し、ｈは１〜３の整数を表す。］

[Wherein, R is the same as above, R ¹² represents a lower alkyl group, and h represents an integer of 1 to 3.] ]

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

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

  In the resin (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, and more preferably 25 to 50 mol% with respect to all the structural units constituting the resin (A1). Is more preferable. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
In addition to the structural unit (a1), the resin (A1) preferably further has a structural unit (a2) that does not have a fluorine atom and is 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. When only the lactone ring is present, 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 resin (A1) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in raising.

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は上記と同様であり、Ｒ’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数であり、Ａは炭素数１〜５のアルキレン基または酸素原子である。］

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

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

  Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-3). Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the resin (A1) is preferably from 5 to 70 mol%, more preferably from 10 to 60 mol%, based on the total of all structural units constituting the resin (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)
In addition to the structural unit (a1) or the structural units (a1) and (a2), the resin (A1) is an acrylic resin that does not have a fluorine atom and contains a polar group-containing aliphatic hydrocarbon group. It is preferable to contain the structural unit (a3) derived from an acid ester.
When the resin (A1) has the structural unit (a3), the hydrophilicity of the component (A) 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, and a carboxy group, and a hydroxyl group is particularly preferable.
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). . 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 these, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyl group, a cyano group, or a carboxy group is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or 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, preferred are a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), and the like. It is done.

［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の整数である。］

[Wherein, R is the same as defined above, j is an integer of 1 to 3, and k 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.
In formula (a3-2), k is preferably 1. The cyano group 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.
In the resin (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, based on all structural units constituting the resin (A1). More preferred is ˜25 mol%.

・ Structural unit (a4)
The resin (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as the structural unit (a4) does not contain a fluorine atom and is not classified into the above-described structural units (a1) to (a3). For ArF excimer laser, KrF excimer laser A number of hitherto known materials can be used as those used for resist resins such as for use (preferably for ArF excimer laser).
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 for 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。］

[Wherein, R is the same as defined above. ]

As the structural unit (a4), one type may be used alone, or two or more types may be used in combination.
When the structural unit (a4) is contained in the resin (A1), the structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 20 based on the total of all the structural units constituting the resin (A1). It is preferable to contain in mol%.

In the present invention, the resin (A1) is preferably a copolymer having at least the structural units (a1), (a2) and (a3). Examples of such a copolymer include the structural unit (a1). , A terpolymer composed of (a2) and (a3), a quaternary copolymer composed of the structural units (a1), (a2), (a3) and (a4).
In the present invention, the resin (A1) is particularly preferably one containing three structural units represented by the following general formula (A1-11).

［式中、Ｒ^４１，Ｒ^４３，Ｒ^４４はそれぞれ独立に水素原子、低級アルキル基、またはフッ素原子以外のハロゲン原子で水素原子が置換された低級アルキル基（ハロゲン化低級アルキル基）であり、Ｒ^４２は低級アルキル基である。］

[Wherein R ⁴¹ , R ⁴³ and R ⁴⁴ are each independently a hydrogen atom, a lower alkyl group, or a lower alkyl group (halogenated lower alkyl group) in which a hydrogen atom is substituted with a halogen atom other than a fluorine atom, ^R42 is a lower alkyl group. ]

In formula (A1-11), the lower alkyl group for R ⁴¹ , R ⁴³ , and R ^{44 is} the same as the lower alkyl group for R above. R ⁴¹ , R ⁴³ and R ⁴⁴ are preferably a hydrogen atom or a lower alkyl group, and preferably a hydrogen atom or a methyl group.
The lower alkyl group for R ^{42 is the same as} the lower alkyl group for R described above, and is preferably a methyl group or an ethyl group, and most preferably a methyl group.

  The resin (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).

(A) Although the mass average molecular weight (Mw) (polystyrene conversion reference | standard by gel permeation chromatography) of the whole component is not specifically limited, 2000-50000 are preferable, 3000-30000 are more preferable, 5000-20000 are preferable. Most preferred. If it is below the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and if it is above the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Moreover, 1.0-5.0 are preferable, as for the dispersity (Mw / Mn) of the whole (A) component, 1.0-3.0 are more preferable, and 1.2-2.5 are the most preferable.
In the positive resist composition for immersion exposure according to the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

In the component (A), the resin (A1) may be used alone or in combination of two or more.
The content of the resin (A1) in the component (A) is preferably in the range of 50 to 100% by mass, more preferably 75 to 100% by mass, and further preferably 80 to 100% by mass. When the content of the resin (A1) is 50% by mass or more, the lithography properties are improved. And since it is especially excellent in the effect of this invention especially, it is most preferable that content of resin (A1) in (A) component is 100 mass%.

<(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, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Examples of the onium salt acid generator include acid generators represented by the following general formula (b-0).

［式中、Ｒ^５１は、直鎖、分岐鎖若しくは環状のアルキル基、または直鎖、分岐鎖若しくは環状のフッ素化アルキル基を表し；Ｒ^５２は、水素原子、水酸基、ハロゲン原子、直鎖若しくは分岐鎖状のアルキル基、直鎖若しくは分岐鎖状のハロゲン化アルキル基、または直鎖若しくは分岐鎖状のアルコキシ基であり；Ｒ^５３は置換基を有していてもよいアリール基であり；ｕ”は１〜３の整数である。］

[Wherein R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, linear or A branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group; R ⁵³ is an optionally substituted aryl group; u "Is an integer from 1 to 3.]

In General Formula (b-0), R ⁵¹ represents a linear, branched, or cyclic alkyl group, or a linear, branched, or cyclic 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 preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
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 the number of substituted fluorine atoms to the total number of hydrogen atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly Those in which all hydrogen atoms are substituted with fluorine atoms are preferred because the strength of the acid is increased.
R ⁵¹ is most preferably a linear alkyl group or a fluorinated alkyl group.

R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, a linear or branched alkyl group, a linear or branched alkyl halide group, or a linear or branched alkoxy group.
In R ⁵² , examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and a fluorine atom is preferable.
In R ⁵² , the alkyl group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
In R ⁵² , the halogenated alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms. Examples of the alkyl group herein are the same as the “alkyl group” in R ⁵² . Examples of the halogen atom to be substituted include the same as those described above for the “halogen atom”. In the halogenated alkyl group, it is desirable that 50 to 100% of the total number of hydrogen atoms are substituted with halogen atoms, and it is more preferable that all are substituted.
In R ⁵² , the alkoxy group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
Among these, R ⁵² is preferably a hydrogen atom.

R ⁵³ is an aryl group which may have a substituent, and examples of the structure of the basic ring (matrix ring) excluding the substituent include a naphthyl group, a phenyl group, an anthracenyl group, and the like. From the viewpoint of absorption of exposure light such as ArF excimer laser, a phenyl group is desirable.
Examples of the substituent include a hydroxyl group and a lower alkyl group (straight or branched chain, preferably having 5 or less carbon atoms, particularly preferably a methyl group).
As the aryl group for R ^53, an aryl group having no substituent is more preferable.
u ″ is an integer of 1 to 3, preferably 2 or 3, and particularly preferably 3.

  Preferable examples of the acid generator represented by the general formula (b-0) include the following.

  Moreover, as an onium salt type acid generator other than the acid generator represented by general formula (b-0), the compound represented by the following general formula (b-1) or (b-2) is mentioned, for example.

［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；Ｒ^４”は、直鎖、分岐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; R ⁴ ″ represents a linear, branched or cyclic alkyl group or fluorinated group. Represents an alkyl group; at least one of R ¹ ″ to R ³ ″ represents an aryl group, and at least one of R ⁵ ″ to R ⁶ ″ represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. 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 of 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 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.
The alkoxy group that may be substituted with a 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, a straight, include alkyl groups such as branched or cyclic. 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.

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 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. It 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.
As the alkyl group for R ⁵ ″ to R ⁶ ″, the same as the alkyl groups for R ¹ ″ to R ³ ″ can be used.
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. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same 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) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate. 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, Preferably it is C3.
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 It is C1-C7, More preferably, it is C1-C3.
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 ″, the strength of the acid increases as the number of hydrogen atoms substituted with fluorine atoms 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.

  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 or a fluorinated alkyl group having 1 to 4 carbon atoms which has no substituent.

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, and still more preferably 90% or more.

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

The alkyl group or halogenated alkyl group having no substituent for R ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group, and most preferably a partially fluorinated alkyl group.
The fluorinated alkyl group in R ³⁵ preferably has 50% or more of the hydrogen atom of the alkyl group, more preferably 70% or more, and even more preferably 90% or more fluorinated. This is preferable because the strength of the acid is increased. Most preferred 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 having no substituent as R ³⁵ described above.
p ″ is preferably 2.

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

  Of the above exemplified compounds, the following four compounds are preferred.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Further, diazomethane acid generators disclosed in JP-A-11-035551, JP-A-11-035552, and JP-A-11-035573 can also be suitably used.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane and 1,4-bis (phenylsulfonyldiazo) disclosed in JP-A-11-322707. Methylsulfonyl) butane, 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane, 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane, 1,3 -Bis (cyclohexylsulfonyldiazomethylsulfonyl) propane, 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane, 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane, etc. Door can be.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, among the above, it is preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).
The content of the component (B) in the positive resist composition for immersion exposure according to the present invention is 0.5 to 30 parts by mass, preferably 1 to 10 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.

<(C) component>
The positive resist composition for immersion exposure of the present invention contains, as component (C), a non-main chain cyclic resin (C1) containing a fluorine atom and having no acid-dissociable group, and a fluorine atom. And a main chain cyclic resin (C2) having no acid-dissociable group.
By containing the component (C), the resist film obtained from the positive resist composition of the present invention has high hydrophobicity on its surface, and suppresses substance elution into an immersion medium such as water as described later. Is done.
Here, in the present specification and claims, the “acid-dissociable group” means a group dissociated by the action of an acid generated from the component (B) by exposure. For example, the lactone-containing cyclic group in the structural unit (a2), the polar group-containing aliphatic hydrocarbon group in the structural unit (a3), the polycyclic aliphatic hydrocarbon group in the structural unit (a4), etc. It is not included in the “dissociable group”.
The acid dissociable group is not particularly limited as long as it is a group dissociated by the action of an acid generated from the component (B). For example, as an acid dissociable, dissolution inhibiting group for a base resin for a chemically amplified resist so far. The suggested one can be used. Specific examples of the acid dissociable, dissolution inhibiting group include those similar to those exemplified as the acid dissociable, dissolution inhibiting group of the structural unit (a1) in the structural unit (a1).
Here, “dissolution inhibition” in the acid dissociable dissolution inhibiting group means that the group has an action (dissolution inhibiting property) for inhibiting the solubility of the component (A) in alkali such as an alkali developer. . In the present invention, the “acid-dissociable group” may have a dissolution inhibiting property or may not have a dissolution inhibiting property.

[Resin (C1)]
The resin (C1) is not particularly limited as long as it is a non-main chain cyclic resin containing a fluorine atom and having no acid dissociable group.
In the present specification and claims, the “non-main chain cyclic resin” means a resin in which none of the carbon atoms constituting the main chain is a carbon atom constituting the ring structure.
By containing the resin (C1) having such a structure, a resist film having a highly hydrophobic surface can be obtained.

  In the present invention, the resin (C1) preferably has an alkali-soluble group. By having an alkali-soluble group, alkali solubility is increased, which contributes to improvement of various lithography properties such as resolution and resist pattern shape. In particular, having an alkali-soluble group containing a fluorine atom, such as a fluorinated hydroxyalkyl group, which will be described later, is excellent in the effect of improving the hydrophobicity of the resist film and suppressing substance elution during immersion exposure. Usefulness for exposure is further improved.

The alkali-soluble group is a group that enhances the alkali solubility of the resin, and is preferably a group having a relatively small pKa (Ka is an acid dissociation constant) similar to the phenolic hydroxyl group, and is not particularly limited. Groups with a pKa in the range of 6-12 are preferred.
More specifically, examples of the alkali-soluble group include a group having —OH at the terminal, such as a hydroxyl group (phenolic hydroxyl group or alcoholic hydroxyl group) or a carboxy group. Specific examples of the alkali-soluble group having —OH at the end include, for example, an alcoholic hydroxyl group; a hydrogen atom bonded to a carbon atom (α-position carbon atom) bonded to a hydroxyl group in a hydroxyalkyl group is substituted with an electron-withdrawing group Group (electron-withdrawing group-substituted hydroxyalkyl group); carboxy group and the like.

Among these, as the alkali-soluble group, an electron-withdrawing group-substituted hydroxyalkyl group is preferable.
In the electron-withdrawing group-substituted hydroxyalkyl group, the alkyl group is preferably linear or branched. Although carbon number of the said electron withdrawing group substituted hydroxyalkyl group is not specifically limited, 1-20 are preferable, 4-16 are more preferable, and it is most preferable that it is 4-12.
The number of hydroxy groups is not particularly limited, but is preferably one.
Examples of the electron withdrawing group include a halogen atom or a halogenated alkyl group.
Examples of the halogen atom include a fluorine atom and a chlorine atom, and a fluorine atom is preferable.
In the halogenated alkyl group, the halogen is the same as the halogen atom, and the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, or a propyl group, more preferably a methyl group or an ethyl group, and most preferably It is a methyl group.
The number of electron-withdrawing groups is 1 or 2, preferably 2.
More specifically and preferably, the electron-withdrawing group-substituted hydroxyalkyl group has a —CR ⁷¹ R ⁷² OH group, and R ⁷¹ and R ⁷² are each independently an alkyl group, a halogen atom, or an alkyl halide. A group, at least one of which can be represented as an electron-withdrawing group selected from a halogen atom or a halogenated alkyl group.

The resin (C1) preferably has a fluorinated hydroxyalkyl group. Thereby, the effect of the present invention is improved. It is also effective in reducing defects and LER (line edge roughness: uneven unevenness of line side walls). 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 between resist patterns, uneven color, and precipitates after development.
Here, the “fluorinated hydroxyalkyl group” is a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a hydroxy group, and the remaining hydrogen atoms (of the alkyl group, Some or all of the hydrogen atoms not substituted with hydroxy groups are substituted by fluorine. In the fluorinated hydroxyalkyl group, the hydrogen atom of the hydroxy group is easily liberated by fluorination.

In the fluorinated hydroxyalkyl group, the alkyl group is preferably linear or branched. Although carbon number of the said alkyl group is not specifically limited, 1-20 are preferable, 4-16 are more preferable, and it is most preferable that it is 4-12. The number of hydroxy groups is not particularly limited, but is preferably one.
Among them, as a fluorinated hydroxyalkyl group, a fluorinated alkyl group and / or a fluorine atom is bonded to the carbon atom to which the hydroxy group is bonded (here, the α-position carbon atom of the hydroxyalkyl group). Those are preferred.
In particular, the fluorinated alkyl group bonded to the α-position is preferably a perfluoroalkyl group in which all of the hydrogen atoms of the alkyl group are substituted with fluorine.
In the present invention, it is particularly preferable that the resin (C1) has a group represented by the following general formula (III).

［式中、ｘは０〜５の整数であり、ｙおよびｚはそれぞれ独立して１〜５の整数である。］

[Wherein, x is an integer of 0 to 5, and y and z are each independently an integer of 1 to 5. ]

In the formula, x is preferably an integer of 0 to 3, and 0 or 1 is particularly preferable.
y and z are preferably integers of 1 to 3, with 1 being most preferred.

The resin (C1) preferably contains a structural unit (a ″) derived from acrylic acid.
Derivatives of acrylic acid include, for example, α-substituted acrylic acid in which a substituent (atom or group other than a hydrogen atom) is bonded to the α-position carbon atom of narrowly defined acrylic acid, or hydrogen of the carboxy group of these acrylic acids Acrylic esters in which atoms are substituted with organic groups.
The “organic group” is a group containing a carbon atom, and the organic group in the acrylate ester is not particularly limited, and examples thereof include the structural unit (a0) and the structural units (a1) to (a4) described later. Groups bonded to the ester side chain of an acrylate ester (a group having a fluorinated hydroxyalkyl group, an acid dissociable, dissolution inhibiting group, a lactone-containing cyclic group, a polar group-containing aliphatic hydrocarbon group) And polycyclic aliphatic hydrocarbon groups).
The α-position (α-position carbon atom) of acrylic acid is a carbon atom to which a carbonyl group is bonded, unless otherwise specified.
Examples of the substituent of α-substituted acrylic acid include a lower alkyl group and a halogenated lower alkyl group.
Specific examples of the lower alkyl group as a substituent at the α-position include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. And a lower linear or branched alkyl group.
As the halogenated lower alkyl group as a substituent at the α-position, a group in which part or all of the hydrogen atoms of the lower alkyl group are substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom and the like. Can be mentioned.
Bonded to the α-position of acrylic acid is preferably a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, more preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, In view of industrial availability, a hydrogen atom or a methyl group is most preferable.
Examples of the structural unit (a ″) include structural units represented by the following general formula (a ″).

［式中、Ｒ^２０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、Ｘは水素原子または１価の有機基である］

[Wherein R ²⁰ is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and X is a hydrogen atom or a monovalent organic group]

Examples of the lower alkyl group or halogenated lower alkyl group for R ²⁰ include those similar to the lower alkyl group or halogenated lower alkyl group as the substituent at the α-position.
Examples of the organic group for X include those similar to the above-mentioned “organic group in acrylic ester”.

The resin (C1) preferably contains the structural unit (a ″) in a proportion of 50 to 100 mol%, based on the total of all the structural units constituting the resin (C1), and contains 70 to 100 mol%. In particular, since the effect of the present invention is particularly excellent, the resin (C1) is preferably composed only of the structural unit (a ″) derived from acrylic acid.
Here, “consisting only of the structural unit (a ″)” means that the main chain of the resin (C1) is composed of only the structural unit (a ″) and does not include other structural units. .

In the present invention, the resin (C1) preferably has a structural unit (a0) derived from an acrylate ester having a fluorinated hydroxyalkyl group in the side chain portion.
Here, in the present specification and claims, the “side chain portion” means a portion that does not constitute the main chain.
Examples of the structural unit (a0) include structural units in which X in the general formula (a ″) is a group having a fluorinated hydroxyalkyl group.
In the present invention, it is particularly preferable that the structural unit (a0) includes a structural unit represented by the following general formula (a0-2).

［式中、Ｒ^２０は水素原子、アルキル基、ハロゲン化アルキル基であり；Ｒ^２２、Ｒ^２３はそれぞれ独立に水素原子または１価の脂肪族環式基であって、Ｒ^２２およびＲ^２３の少なくとも１つは脂肪族環式基であり；ｆは０〜５の整数であり；ｂ、ｃはそれぞれ独立に１〜５の整数である。］

^{Wherein, R 20} is a hydrogen atom, an alkyl group, a halogenated alkyl ^group; a R ^{22, R 23} are each independently a hydrogen atom or a monovalent aliphatic cyclic ^group, the ^{R 22} and ^{R 23} At least one is an aliphatic cyclic group; f is an integer of 0 to 5; b and c are each independently an integer of 1 to 5. ]

The structural unit represented by the general formula (a0-2) (hereinafter referred to as the structural unit (a0-2)) has one hydrogen atom of a methyl group, — (CH ₂ ) _f —C (C _b F _{2b + 1} ) (C _c F _{2c + 1} ) —OH and a structural unit having a group substituted with one or two aliphatic cyclic groups.
R ²⁰ in the general formula (a0-2) are the same groups as those with R ²⁰ in the above-mentioned formula (a "), preferably a hydrogen atom or a lower alkyl group, most preferably a hydrogen atom or a methyl group .
b and c are each independently an integer of 1 to 5, preferably an integer of 1 to 3, and 1 is most preferable.
f is preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and 1 is most preferable.

R ²² and R ²³ are each independently a hydrogen atom or a monovalent aliphatic cyclic group, and at least one of R ²² and R ²³ is an aliphatic cyclic group.
In the present invention, it is particularly preferable that one of R ²² and R ²³ is a hydrogen atom and the other is an aliphatic cyclic group.
The aliphatic cyclic group for R ²² and R ²³ may be monocyclic or polycyclic. “Monocyclic aliphatic cyclic group” means a monocyclic group having no aromaticity, and “polycyclic aliphatic cyclic group” means a polycyclic group having no aromaticity. Means a cyclic group.
An aliphatic cyclic group is a hydrocarbon group composed of carbon and hydrogen (alicyclic group), and a part of the carbon atoms constituting the ring of the alicyclic group is a heterogeneous group such as an oxygen atom, a nitrogen atom, or a sulfur atom. Heterocyclic groups and the like substituted with atoms are included. As the aliphatic cyclic group, an alicyclic group is preferable.
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). .
The aliphatic cyclic group for R ²² and R ²³ preferably has 5 to 15 carbon atoms, and more preferably 6 to 12 carbon atoms. Of these, a group in which one or more hydrogen atoms have been removed from cyclohexane, cyclopentane, norbornane, tricyclodecane or tetracyclododecane is preferred, and a group in which one or more hydrogen atoms have been removed from cyclohexane is particularly preferred.

  In the present invention, as the structural unit (a0-2), in particular, the structural unit represented by the following general formula (a0-2-1) is effective, easy to synthesize, and has high etching resistance. It is preferable from the point which is made.

［式中、Ｒ^２０，ｆ，ｂ，ｃは上記と同様である。］

[Wherein R ²⁰ , f, b and c are the same as above. ]

  In the present invention, the structural unit (a0) includes a fluorinated hydroxyalkyl group and a monocyclic or polycyclic aliphatic cyclic group in the side chain as in the structural unit (a0-2). The structural unit represented by formula (a0-2-1) is particularly preferable.

As the structural unit (a0), one type may be used alone, or two or more types may be used in combination.
In the resin (C1), the proportion of the structural unit (a0) is preferably from 30 to 100 mol%, more preferably from 50 to 100 mol%, based on the total of all the structural units constituting the resin (C1), and from 70 to 100 mol% is more preferable, and 100 mol% is most preferable. By being 30 mol% or more, the effect by containing a structural unit (a0) is high, for example, even if the ratio of resin (C1) in a resist composition is small, high immersion medium tolerance is acquired. As a result, the lithography properties are improved.

-Other structural unit Resin (C1) may contain other structural units other than the said structural unit (a0) in the range which does not impair the effect of this invention.
The other structural unit is not classified into the above structural unit (a0), has no acid-dissociable group, and none of the carbon atoms constituting the main chain constitutes a ring structure. There is no particular limitation as long as it is a structural unit derived from a monomer that can be copolymerized with a monomer that derives the structural unit (a0). For ArF excimer laser, for KrF excimer laser (preferably for ArF excimer laser), etc. A large number of hitherto known materials can be used for these resist resins. Specifically, as such other structural units, for example, among the structural units (a2) to (a4) and the like mentioned in the resin (A1), the carbon atoms constituting the main chain all form a ring structure. Those that are not atoms.

  In the resin (C1), the combination and ratio of the structural unit (a0) and other structural units can be appropriately adjusted depending on the required characteristics and the like. However, as described above, the effect of the present invention is particularly excellent. The resin (C1) is preferably composed only of the structural unit (a0).

  Resin (C1) is a radical polymerization initiator such as azobisisobutyronitrile (AIBN) or dimethyl-2,2′-azobis (2-methylpropionate), which is a monomer derived from each structural unit. It can obtain by making it superpose | polymerize by well-known radical polymerization etc. using this.

The mass average molecular weight (Mw; polystyrene-converted mass average molecular weight by gel permeation chromatography) of the resin (C1) is not particularly limited, but is preferably 2000 to 40000, more preferably 2000 to 30000, and more preferably 3000 to 25000. preferable. By setting it within this range, a good dissolution rate in an alkali developer can be obtained, which is preferable from the viewpoint of high resolution. Within this range, the lower the molecular weight, the better characteristics tend to be obtained.
The dispersity (Mw / Mn) is about 1.0 to 5.0, preferably 1.0 to 3.0.

In the component (C), the resin (C1) may be used alone or in combination of two or more.
The content of the resin (C1) in the component (C) is preferably 0.1% by mass or more, more preferably in the range of 0.1 to 90% by mass, and 5 to 90% by mass. More preferably, 10-85 mass% is especially preferable, and 15-80 mass% is the most preferable. When the content of the resin (C1) is 0.1% by mass or more, the resistance of the resist film to the immersion medium is improved. Moreover, the lithography characteristic improves that it is 90 mass% or less.

[Resin (C2)]
The resin (C2) is a main chain cyclic resin containing a fluorine atom and having no acid dissociable group.
Here, the “acid-dissociable group” is the same as described above. For example, —Q—NH—SO ₂ —R ⁵ in the structural unit (a′1) described later is included in the “acid-dissociable group”. Absent.

In the present specification and claims, the term “main chain cyclic resin” means that the structural unit constituting the resin has a monocyclic or polycyclic ring structure, and the ring is on the ring of the ring structure. It means that at least one, preferably two or more carbon atoms have a structural unit constituting the main chain (hereinafter sometimes referred to as main chain cyclic structural unit).
By containing the resin (C2) having such a structure, a resist film having a high hydrophobicity on the film surface can be obtained as in the case of containing the resin (C1). In addition, etching resistance is improved. The improvement in etching resistance is presumed to be because the carbon density is increased by having the main chain cyclic structural unit.

Examples of the main chain cyclic structural unit include structural units derived from polycycloolefins (polycyclic olefins), dicarboxylic acid anhydride-containing structural units listed in the structural unit (a′3) described later, and the like. .
Among these, it is preferable to have a structural unit derived from a polycycloolefin in the main chain because the etching resistance when used as a resist is particularly excellent.
As the structural unit derived from polycycloolefin, a structural unit having a basic skeleton represented by the following general formula (a ′) is preferable.

［式中、ａは０または１である。］

[Wherein, a is 0 or 1; ]

In the formula (a ′), a is 0 or 1, and is preferably 0 in consideration of industrial availability.
The “structural unit having the basic skeleton represented by the general formula (a ′)” is a structural unit represented by the general formula (a ′) (that is, from bicyclo [2.2.1] -2-heptene (norbornene). the induced structural units, and tetracyclo ^{[4.4.0.1 2.5 .1.} 7.10] -3- dodecene may be a structural unit) derived from, also described below structural unit ( As in a′1) to (a′3), the ring skeleton may have a substituent. That is, the “structural unit having the basic skeleton represented by the general formula (a ′)” includes the ring skeleton (bicyclo [2.2.1] -2-heptane or tetracyclo [4.4.0.1 ^{2]. .5,} 7.1, ^7.10 ] -3-dodecane) includes a structural unit in which part or all of the hydrogen atoms bonded to the carbon atom constituting the structural unit are substituted with atoms or substituents other than hydrogen atoms.

The resin (C2) may have a structural unit other than the main chain cyclic structural unit, for example, the structural unit (a) (structural unit derived from acrylic acid) mentioned in the resin (A1). In order to achieve the effect of the present invention, the main chain cyclic structural unit is preferably contained in the resin (C2) in an amount of 50 to 100 mol% with respect to all the structural units constituting the resin (C2). It is more preferable that 80-100 mol% is contained. In particular, since the effect of the present invention is particularly excellent, the resin (C2) is preferably composed only of a main chain cyclic structural unit.
Here, “consisting only of the main chain cyclic structural unit” means that the main chain of the resin (C2) is composed of only the main chain cyclic structural unit and does not include other structural units. .

・ Structural unit (a'1)
The resin (C2) preferably has a structural unit (a′1) represented by the following general formula (I) because the effect of the present invention is excellent.

［式（Ｉ）中、Ｒ^１〜Ｒ^４は、それぞれ独立に、水素原子、直鎖もしくは分岐鎖状のアルキル基、直鎖もしくは分岐鎖状のフッ素化アルキル基、または下記一般式（Ｉａ）で表される基（Ｉａ）であり、Ｒ^１〜Ｒ^４のうち少なくとも１つは前記基（Ｉａ）であり；ａは０または１である。］

[In the formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom, a linear or branched alkyl group, a linear or branched fluorinated alkyl group, or the following general formula (Ia) And at least one of R ^{1 to} R ⁴ is the group (Ia); a is 0 or 1; ]

［式（Ｉａ）中、Ｑは炭素数１〜５の直鎖または分岐鎖状のアルキレン基であり；Ｒ^５はフッ素化アルキル基である。］

[In Formula (Ia), Q is a linear or branched alkylene group having 1 to 5 carbon atoms; R ⁵ is a fluorinated alkyl group. ]

The structural unit (a′1) represented by the general formula (I) is a structural unit having the basic skeleton represented by the general formula (a ′), and has a substituent at a specific position on the ring. At least the group (Ia) represented by the general formula (Ia) is included.
In the present invention, the hydrophobicity of the resist film surface is improved by having such a structural unit. In addition, lithography properties are improved. The reason why such an effect is obtained is not clear, but by having the group (Ia), the effect of improving the hydrophobicity of the resist film by fluorine atoms can be obtained, and the alkali solubility of the resin (C2) can be improved. This is presumed to contribute to improvement of various lithography characteristics such as resolution and resist pattern shape.

In the formula (I), a is the same as a in the above formula (a ′).
The alkyl group of R ^{1 to} R ⁴ may be linear or branched, is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and an alkyl group having 1 to 5 carbon atoms. More preferred are groups. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a pentyl group, an isopentyl group, and a neopentyl group.
The fluorinated alkyl group of R ^{1 to} R ⁴ is a group in which part or all of the hydrogen atoms of a linear or branched alkyl group are substituted with fluorine atoms. Examples of the alkyl group in the fluorinated alkyl group include the same alkyl groups as those described above for R ^{1 to} R ⁴ .
The fluorination rate of the fluorinated alkyl group (ratio of the number of fluorine atoms to the total number of hydrogen atoms and fluorine atoms in the fluorinated alkyl group (%)) is preferably 10 to 100%, and preferably 30 to 100 % Is more preferable, and 50 to 100% is more preferable. When the fluorination rate is 10% or more, the effect of improving the hydrophobicity of the resist film surface is excellent.

  In general formula (Ia), the alkylene group of Q may be linear or branched, is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 8 carbon atoms, and 1 to 1 carbon atoms. More preferred is an alkylene group of 5. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a pentene group, an isopentene group, and a neopentene group. Among these, a linear alkylene group is preferable from the viewpoint of ease of synthesis, and a methylene group is particularly preferable.

The fluorinated alkyl group for R ⁵ is a group in which part or all of the hydrogen atoms of a linear, branched or cyclic alkyl group are substituted with fluorine atoms.
Examples of the linear or branched alkyl group include the same as the fluorinated alkyl groups for R ^{1 to} R ⁴ .
The cyclic alkyl group preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
The fluorination rate of the fluorinated alkyl group (ratio of the number of fluorine atoms to the total number of hydrogen atoms and fluorine atoms in the fluorinated alkyl group (%)) is preferably 10 to 100%, and preferably 30 to 100 % Is more preferable, 50 to 100% is particularly preferable, and it is most preferable that 100%, that is, all hydrogen atoms are substituted with fluorine atoms. When the fluorination rate is 10% or more, the effect of improving the hydrophobicity of the resist film surface is excellent. Therefore, even if the ratio of the resin (C2) in the component (C) is small, a sufficient hydrophobicity improving effect can be obtained.
As the fluorinated alkyl group for R ⁵ , a linear or branched fluorinated alkyl group is preferable, a fluorinated alkyl group having 1 to 5 carbon atoms is more preferable, and in particular, all the hydrogen atoms of the alkyl group are fluorine atoms. A substituted perfluoroalkyl group is preferred. Specific examples of the perfluoroalkyl group include a trifluoromethyl group and a pentafluoroethyl group, and a trifluoromethyl group is preferable.

In the present invention, at least one of R ^{1 to} R ⁴ is the group (Ia) represented by the general formula (Ia), and the remaining 0 to 3 are a hydrogen atom, a straight chain or a branched chain. One or more selected from an alkyl group and a linear or branched fluorinated alkyl group. In the present invention, ^one of R ^{1 to} R ⁴ is preferably the group (Ia), and in particular, ^one of R ^{1 to} R ⁴ is the group (Ia) and the other three are hydrogen. An atom is preferred.

  As the structural unit (a′1), a structural unit represented by general formula (Ib) shown below is particularly desirable.

In the formula (Ib), a is the same as described above.
p is an integer of 1 to 10, an integer of 1 to 8 is preferable, and 1 is most preferable.
q is an integer of 1 to 5, preferably an integer of 1 to 4, and most preferably 1.

As the structural unit (a′1), one type of structural unit may be used alone, or two or more types may be used in combination.
The resin (C2) preferably contains the structural unit (a′1) in a proportion of 50 to 100 mol%, based on the total of all the structural units constituting the resin (C2), and is 80 to 100 mol%. It is more preferable to contain. In particular, since the effect of the present invention is particularly excellent, it is preferable that the resin (C2) is composed only of the structural unit (a′1).
Here, “consisting only of the structural unit (a′1)” means that the main chain of the resin (C2) is composed of only the structural unit (a′1) and does not include other structural units. means.

  The monomer for deriving the structural unit (a′1) can be synthesized, for example, by the technique disclosed in US Pat. No. 6,420,503.

・ Other structural units (a'3)
The resin (C2) may contain a structural unit (a′3) other than the structural unit (a′1) as long as the effects of the present invention are not impaired.
The structural unit (a ′ 3) is a structural unit that does not have an acid-dissociable group and is not classified as the structural unit (a ′ 1), and is a monomer that derives the structural unit (a ′ 1). There is no particular limitation as long as it is a structural unit derived from a polymerizable monomer.
As the structural unit (a ′ 3), a structural unit derived from a known compound having an ethylenic double bond can be arbitrarily used depending on the purpose.

  More specifically, as the structural unit (a ′ 3), for example, a structural unit derived from acrylic acid such as the structural unit (a2) to the structural unit (a4) listed in the resin (A1), a dicarboxylic acid Examples include an anhydride-containing structural unit, a structural unit derived from a polycycloolefin having no substituent, and a structural unit derived from a polycycloolefin having a polycyclic alicyclic group as a substituent.

  The acid anhydride-containing structural unit of dicarboxylic acid refers to a structural unit having a —C (O) —O—C (O) — structure. Examples of such include structural units containing monocyclic or polycyclic cyclic acid anhydrides, and more specifically, monocyclic anhydrous represented by the following formula (a′31): Structural units derived from maleic acid, structural units derived from polycyclic maleic anhydride represented by the following formula (a′32), and structural units derived from itaconic acid represented by the following formula (a′33) Etc.

Examples of the structural unit derived from a polycycloolefin having no substituent include bicyclo [2.2.1] -2-heptene (norbornene), tetracyclo [4.4.0.1 ^2.5 . 1. ^7.10 ] -3-dodecene and the like.
In addition, as a structural unit derived from a polycycloolefin having a polycyclic alicyclic group as a substituent, as a substituent on the ring of the structural unit derived from a polycycloolefin having no substituent, Examples include structural units having a polycyclic group such as a tricyclodecanyl group, an adamantyl group, and a tetracyclododecanyl group.

  In the resin (C2), the combination and ratio of the structural units such as the structural units (a′1) and (a′3) can be appropriately adjusted according to required characteristics. However, as described above, since the effect of the present invention is particularly excellent, the resin (C2) is preferably composed only of the structural unit (a′1).

  The resin (C2) is obtained, for example, by polymerizing a monomer that derives a predetermined structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). Can do.

The mass average molecular weight (Mw; polystyrene-converted mass average molecular weight by gel permeation chromatography (GPC). The same applies hereinafter) of the resin (C2) is not particularly limited, but is preferably 20000 or less, and more preferably 10,000 or less. When the Mw is 20000 or less, the effect of the present invention is improved, and in particular, lithography properties such as resolution are improved. Moreover, it is excellent in solubility in an organic solvent and the like, and generation of foreign matters, development defects, and the like can be suppressed. Here, the foreign matter is a solid matter such as a particulate matter generated in the solution when the composition is used as a solution.
The development defect is a general defect detected when the developed resist pattern is observed from directly above, for example, by 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. The lower limit of Mw is not particularly limited, but is preferably 2000 or more, and more preferably 4000 or more. When Mw is 4000 or more, there are advantages such as improved etching resistance, resist pattern swelling less during development, and pattern collapse less likely to occur.
The dispersity (Mw / Mn (number average molecular weight)) is preferably about 1.0 to 5.0, and more preferably 1.0 to 3.0.

In the component (C), the resin (C2) may be used alone or in combination of two or more.
The content of the resin (C2) in the component (C) is preferably 0.1% by mass or more, more preferably in the range of 0.1 to 95% by mass, and 10 to 95% by mass. More preferably, 15 to 90 mass% is particularly preferable, and 20 to 85 mass% is most preferable. When the content of the resin (C2) is 0.1% by mass or more, the resistance of the resist film to the immersion medium is improved. Moreover, the lithography characteristic improves that it is 50 mass% or less.

  The content of the component (C) relative to the component (A) is preferably 0.1% by mass or more, more preferably in the range of 0.1 to 50% by mass, and 0.5 to 25% by mass. Is more preferable, 1.0-20 mass% is especially preferable, and 1.5-10 mass% is the most preferable. When the content of the component (C) with respect to the component (A) is 0.1% by mass or more, the resistance of the resist film to the immersion medium is improved. Moreover, when it is 50 mass% or less, a balance with (A) component becomes favorable and a lithography characteristic improves.

  Since the resins (C1) and (C2) used as the component (C) in the present invention do not have an acid dissociable group, they are generally used as a base resin for a positive resist composition, for example. Compared to existing resins (resins having acid dissociable, dissolution inhibiting groups), they have advantages such as easy synthesis and availability at low cost.

<Optional component>
In the positive resist composition for immersion exposure according to the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as (D)) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Component)).
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms. Specific examples thereof include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n-heptylamine, Dialkylamines such as di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptyl Trialkylamines such as amine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n -Ok Noruamin, alkyl alcohol amines such as tri -n- octanol amine.
Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are most preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.

Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.

These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

The positive resist composition for immersion exposure of the present invention includes an organic carboxylic acid and phosphorus oxo as optional components for the purpose of preventing sensitivity deterioration and improving the resist pattern shape and stability with time. At least one compound (E) selected from the group consisting of acids and derivatives thereof (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 used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  The positive resist composition for immersion exposure according to the present invention may further contain a miscible additive as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

The positive resist composition for immersion exposure 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, and any one of conventionally 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, and 2-heptanone; many such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol Monohydric alcohols and derivatives thereof; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether of the polyhydric alcohols or the compound having an ester bond , Monoalkyl ether such as monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether Derivatives of polyhydric alcohols such as compounds having an ether bond: cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate Esters such as methyl methoxypropionate and ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butyl phenyl ether, ethyl benzene, diethyl benzene, pentyl benzene, isopropyl benzene, toluene, Aromatic organic solvents such as xylene, cymene and mesitylene can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Of 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 preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is 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.
Moreover, what mixed the mixed solvent of said PGMEA and PGME, and (gamma) -butyrolactone as (S) component is preferable.
The amount of component (S) used is not particularly limited, but it 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 5-15% by mass.

  The material can be dissolved in the component (S), for example, by simply mixing and stirring the above components by a usual method. If necessary, a disperser such as a dissolver, a homogenizer, or a three-roll mill is used. It may be dispersed and mixed. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

As described above, the positive resist composition for immersion exposure of the present invention can form a highly hydrophobic resist film on the film surface. Further, the lithography characteristics are also good, which is suitable when a resist pattern is formed using immersion exposure.
The reason why such an effect is obtained is not clear, but the resins (C1) and (C2) have a structure containing a fluorine atom and no acid dissociable group, and the resin (A1) contains a fluorine atom. Since it has an acrylic structure not included, when a resist film is formed using the positive resist composition for immersion exposure, the relatively hydrophobic resins (C1) and (C2) It is presumed that the resin (A1) distributed near the outer surface and relatively hydrophilic is distributed inside the resist film. Further, since the resins (C1) and (C2) are distributed near the outer surface of the resist film, for example, the hydrophobicity of the obtained resist film surface is improved as compared with the case where the resin (A1) is used alone, and the resin It is estimated that (A1) is distributed on the inner side of the resist film, so that good lithography characteristics are ensured.

Such a resist film has excellent resistance to an immersion medium, such as suppression of elution (substance elution) of components in the resist film into the immersion solvent when the immersion exposure process is performed. It is suitable for use.
That is, the resist film formed using the positive resist composition for immersion exposure according to the present invention has, for example, a contact angle [for example, a static contact angle ( The angle between the surface of the water droplet on the resist film in the horizontal state and the surface of the resist film), dynamic contact angle (contact angle when the water droplet starts to fall when the resist film is tilted. Contact angle (advance angle) at the end point and contact angle (retreat angle) at the end point in the fall direction))) or fall angle (drops of water began to fall when the resist film was tilted) The inclination angle of the resist film changes. Specifically, the static contact angle and the dynamic contact angle are increased, while the falling angle is decreased.
Here, as shown in FIG. 1, when the plane 2 on which the droplet 1 is placed is gradually inclined, the advance angle starts to move (drop) on the plane 2 when the droplet 1 is gradually inclined. Is the angle θ ₁ formed by the surface of the droplet at the lower end 1 a of the droplet 1 and the plane 2. At this time (when the droplet 1 starts moving (falling) on the plane 2), the angle θ2 formed by the droplet surface at the upper end 1b of the droplet 1 and the plane ₂ is the receding angle, The inclination angle θ _{3 of the} plane 2 is the falling angle.

In immersion exposure, as described above, the resist film comes into contact with an immersion solvent such as water during immersion exposure. Therefore, it is presumed that substance elution is influenced by the characteristics (for example, hydrophilicity / hydrophobicity) of the resist film surface.
In the present invention, by using the specific component (C), the hydrophobicity of the film surface is improved, so that the substance elution suppressing effect is also improved. By increasing the hydrophobicity of the membrane surface, the immersion medium can be easily repelled from the membrane surface, the contact area and contact time between the membrane surface and the immersion medium can be reduced, and the influence of the immersion medium can be reduced. It is estimated that. For example, after the immersion exposure, the immersion medium can be quickly removed from the resist film surface when the immersion medium is removed.

The static contact angle, dynamic contact angle, and sliding angle can be measured, for example, as follows.
First, a resist composition solution is spin-coated on a silicon substrate, and then heated for 60 seconds under a predetermined condition, for example, a temperature condition of 100 to 110 ° C., to form a resist film.
Next, DROP MASTER-700 (manufactured by Kyowa Interface Science Co., Ltd.), AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.) It can measure using commercially available measuring apparatuses, such as.

  In the positive resist composition for immersion exposure according to the present invention, the measured value of the receding angle in a resist film obtained using the positive resist composition is preferably 60 ° (°) or more, and preferably 60 to 150 °. Is more preferable, 60 to 130 ° is particularly preferable, and 65 to 100 ° is most preferable. When the receding angle is 60 ° or more, the resist film surface is excellent in hydrophobicity and the substance elution suppression effect is improved, and when the receding angle is 150 ° or less, the lithography characteristics and the like are good.

  For the same reason, in the positive resist composition for immersion exposure according to the present invention, the measured value of the advance angle in a resist film obtained using the resist composition is preferably 80 ° or more, and 80 to 110 °. It is more preferable that it is 80-100 degrees.

  For the same reason, the positive resist composition for immersion exposure of the present invention preferably has a measured value of a static contact angle in a resist film obtained by using the resist composition of 70 ° or more. 100 ° is more preferable, and 75 to 95 ° is particularly preferable.

  Further, in the resist composition for immersion exposure according to the present invention, the measured value of the falling angle in the resist film obtained using the resist composition is preferably 25 ° or less, more preferably 10 to 25 °. It is preferably 12 to 25 °, and most preferably 15 to 23 °. When the falling angle is 25 ° or less, the substance elution suppression effect during immersion exposure is improved. Further, when the falling angle is 10 ° or more, the lithography properties and the like are good.

  The size of the static contact angle, dynamic contact angle, and sliding angle depends on the composition of the positive resist composition for immersion exposure, for example, the mixing ratio of the (A) component and the (C) component, It can be adjusted by adjusting the proportion of each structural unit such as the structural unit (a3). For example, by setting the content of the component (C) with respect to the component (A) to be 0.1% by mass or more, the static contact angle and the dynamic contact angle are significantly larger than when the component (C) is not added. Increases and decreases the sliding angle.

Furthermore, in the present invention, as described above, substance elution into the immersion solvent is suppressed.
For this reason, it is possible to suppress the alteration of the resist film and the change in the refractive index of the immersion solvent. Therefore, by suppressing the change in the refractive index of the immersion solvent, the swell of the formed resist pattern and the line edge roughness (unevenness on the pattern side wall) are reduced, and the lithography properties such as the shape are improved. Further, the contamination of the lens of the exposure apparatus can be reduced, so that it is not necessary to take a protective measure against these, and the process and the exposure apparatus can be simplified.
Moreover, according to the positive resist composition for immersion exposure of the present invention, a high-resolution resist pattern can be formed, for example, a resist pattern having a dimension of 120 nm or less can be formed.
Moreover, by using the positive resist composition for immersion exposure according to the present invention, it is possible to form a resist pattern having a good shape in which the generation of foreign matters and development defects is suppressed.

≪Resist pattern formation method≫
Next, the resist pattern forming method of the present invention will be described.
The resist pattern forming method of this aspect includes a step of forming a resist film on a support using the positive resist composition for immersion exposure of the present invention, a step of immersing the resist film, and And developing to form a resist pattern.
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.
In addition, 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 resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the resist composition of the present invention is applied onto a substrate such as a silicon wafer with a spinner or the like, and pre-baking (post-apply baking (PAB)) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds. Preferably, it is applied for 60 to 90 seconds to form a resist film. The resist film is selectively exposed (immersion exposure) in an immersion medium using a predetermined exposure light source with or without a desired mask pattern. That is, exposure is performed through a mask pattern in an immersion medium, or drawing is performed by direct irradiation with an electron beam without using a mask pattern.
After the selective exposure, heat treatment (post-exposure baking (PEB)) is performed 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), and preferably rinsed with pure water. The water rinsing can be performed, for example, by dropping or spraying water on the substrate surface while rotating the substrate to wash away the developer on the substrate and the resist composition for immersion exposure dissolved by the developer. And a resist pattern can be formed by drying.
An organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.
The wavelength used for the exposure is not particularly limited, and includes KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. Among these, the resist composition of the present invention is particularly effective for ArF excimer laser.

<Immersion exposure>
As described above, the positive resist composition of the present invention can be suitably used for immersion exposure.
The step of immersing and exposing the resist film can be performed, for example, as follows.
First, the space between the resist film obtained as described above and the lens at the lowest position of the exposure apparatus is filled with a solvent (immersion medium) having a refractive index larger than the refractive index of air. Exposure (immersion exposure) is performed with or without a mask pattern.

As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film formed using the positive resist composition of the present invention is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, and a silicon-based solvent.
Specific examples of the fluorine-based inert liquid include a fluorine-based compound such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).

  Since the positive resist composition of the present invention is not particularly adversely affected by water and is excellent in sensitivity and resist pattern shape, water is preferably used as a solvent having a refractive index larger than that of air. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

  Next, after the immersion exposure step is completed, post-exposure heating (post-exposure baking (PEB)) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. In the water rinse, for example, water is dropped or sprayed on the surface of the substrate while rotating the substrate to wash away the developer on the substrate and the positive resist composition for immersion exposure dissolved by the developer. Then, drying is performed to obtain a resist pattern in which the resist film (the coating film of the positive resist composition for immersion exposure) is patterned into a shape corresponding to the mask pattern.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
[Example 1, Comparative Examples 1-2]
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] of Table 1 is a compounding quantity (mass part).
(A) -1: a polymer represented by the following chemical formula (A) -1. In chemical formula (A) -1, the number attached to the lower right of () indicates the proportion (mol%) of each structural unit.
(B) -1: (4-methylphenyl) diphenylsulfonium nonafluoro-n-butanesulfonate.
(C) -1 and (C) -3: polymers represented by the following chemical formulas (C) -1 and (C) -3, respectively. In chemical formulas (C) -1 and (C) -3, the numbers attached to the lower right of () indicate the proportion (mol%) of the structural units.
(D) -1: tri-n-pentylamine.
(E) -1: salicylic acid.
(O) -1: Surfactant XR-104 (Dainippon Ink Chemical Co., Ltd.)
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.
(S) -2: γ-butyrolactone.

［Ｍｗ＝７０００、Ｍｗ／Ｍｎ＝１．７。］

[Mw = 7000, Mw / Mn = 1.7. ]

［Ｍｗ＝１９０００、Ｍｗ／Ｍｎ＝１．４。］

[Mw = 19000, Mw / Mn = 1.4. ]

［Ｍｗ＝５０００、Ｍｗ／Ｍｎ＝１．４。］

[Mw = 5000, Mw / Mn = 1.4. ]

The (A) -1 was obtained by copolymerization by a known dropping polymerization method using a monomer for deriving each structural unit.
The (C) -1 was obtained by polymerization using a monomer that induces a structural unit by a known dropping polymerization method.

The following evaluation was performed using the obtained positive resist composition solution.
<Hydrophobic evaluation>
The hydrophobicity of the resist film was evaluated by measuring the static contact angle, the falling angle, and the receding angle (hereinafter referred to as contact angle) of the resist film surface before and after exposure in the following procedure.
The resist compositions of Example 1 and Comparative Examples 1 and 2 are applied onto an 8-inch silicon wafer using a spinner, and prebaked (PAB) at 110 ° C. for 60 seconds on a hot plate and dried. Thus, a resist film having a thickness of 150 nm was formed.
50 μL of water was dropped onto the surface of the resist film (resist film before exposure), and the contact angle and the like were measured using DROP MASTER-700 manufactured by Kyowa Interface Science Co., Ltd.

In addition, a resist film is formed in the same manner as described above, and ArF excimer laser (193 nm) is used using an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, σ = 0.75). Then, open frame exposure (exposure not through a mask) was performed (exposure amount 20 mJ / cm ² ), and the contact angle of the resist film (resist film after exposure) surface was measured in the same manner as described above.
Table 2 shows the measurement results such as the contact angle of the resist film before and after exposure.

  As shown in these results, the resist film obtained using the resist composition of Example 1 was more exposed to light before exposure than the resist film obtained using the resist compositions of Comparative Examples 1 and 2. Later, the static contact angle and receding angle increased, and the sliding angle decreased, and it was confirmed that a highly hydrophobic film could be obtained by adding (C) -1 and (C) -3. It was.

<Measurement of eluate>
A resist film was formed in the same manner as in the hydrophobicity evaluation except that an 8-inch silicon wafer subjected to hexamethyldisilazane (HMDS) treatment on the surface was used.
Next, using VRC310S (trade name, manufactured by S.E.S. Co., Ltd.), 1 drop (50 μl) of pure water is moved at room temperature to draw a circle from the center of the wafer at a constant linear velocity. (The total contact area of the resist film in contact with the droplet was 221.56 cm ² ).
Thereafter, the droplets are collected and analyzed by an analyzer Agilent-HP1100 LC-MSD (trade name, manufactured by Agilent Technologies), and the cation part (PAG +) and anion part (PAG) of the component (B) before exposure. -) And the elution amount of component (D) (× 10 ⁻¹² mol / cm ² ) were measured, and the total amount (× 10 ⁻¹² mol / cm ² ) was determined. These results are shown in Table 3.

In addition, a resist film is formed in the same manner as described above, and ArF excimer laser (193 nm) is used using an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, σ = 0.75). Then, open frame exposure (exposure without a mask) was performed (exposure amount 20 mJ / cm ² ).
Next, the exposed resist film was analyzed in the same manner as described above, and the cation portion (PAG +) and anion portion (PAG−) of the component (B) after exposure and the elution amount of the component (D) (× 10 ^{− 12} mol / cm ²⁾ was measured and determined their total amount ^{(× 10 -12 mol / cm 2} ). These results are shown in Table 3.

  From the results of Table 3, when the resist composition of Example 1 was used, the total elution amount of the (B) component and the (D) component in the immersion medium (water) before and after the exposure treatment was reduced. It was confirmed that the substance elution suppression effect during immersion exposure was high.

<Lithography characteristics evaluation>
"Resolution and sensitivity"
About the resist composition of Example 1 and Comparative Examples 1-2, the resist pattern was formed in the following procedures, respectively.
An organic antireflection film composition “ARC-29A” (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. Thereby, an organic antireflection film having a thickness of 77 nm was formed. The resist compositions of Example 1 and Comparative Examples 1 and 2 are applied onto the antireflection film using a spinner, prebaked (PAB) at 120 ° C. for 60 seconds on a hot plate, and dried. Thus, a resist film having a thickness of 150 nm was formed.
For the resist film, an ArF excimer laser (193 nm) is selected through a mask pattern using an ArF exposure apparatus NSR-S302 (Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). Irradiated. Then, PEB processing is performed at 110 ° C. for 60 seconds, and further development processing is performed for 30 seconds with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ° C., and then pure water is used for 30 seconds. A line-and-space resist pattern (hereinafter referred to as an L / S pattern) having a line width of 120 nm and a pitch of 240 nm was formed by rinsing with water and drying by shaking.
At this time, the optimum exposure amount (Eop) (unit: mJ / cm ² (energy amount per unit area)), that is, the sensitivity at which an L / S pattern having a line width of 120 nm and a pitch of 240 nm is formed was determined. As a result, the sensitivity was equivalent in any of the resist compositions.

"LWR (Line Wise Roughness)"
In each L / S pattern formed by the Eop, the line width is adjusted in the longitudinal direction of the line by a length measuring SEM (scanning electron microscope, acceleration voltage 800 V, product name: S-9220, manufactured by Hitachi, Ltd.). Five locations were measured, and from the result, a triple value (3 s) of the standard deviation (s) was calculated as a scale indicating LWR. The smaller the value of 3s, the smaller the roughness of the line width, which means that a more uniform width L / S pattern was obtained. As a result, the value of 3 s was the same in any example using any resist composition.

“MEF (Mask Error Factor)”
In the above Eop, an L / S pattern is formed using a mask pattern that targets an L / S pattern with a line width of 120 nm and a pitch of 260 nm and a mask pattern that targets an L / S pattern with a line width of 130 nm and a pitch of 260 nm. And the value of MEF was calculated | required from the following formula | equation.
MEF = | CD ₁₃₀ −CD ₁₂₀ | / | MD ₁₃₀ −MD ₁₂₀ |
In the above formula, CD ₁₃₀ and CD ₁₂₀ are the actual line widths (nm) of the L / S pattern formed using a mask pattern targeting a line width of 120 nm and a line width of 130 nm, respectively. MD ₁₃₀ and MD ₁₂₀ are line widths (nm) targeted by the mask pattern, respectively, and MD ₁₃₀ = 130 and MD ₁₂₀ = 120. MEF is a parameter indicating how faithfully mask patterns with different line widths and apertures can be reproduced with the same exposure when the pitch is fixed (mask reproducibility). The closer it is, the better the mask reproducibility is. As a result, it was the same value in any of the examples using the resist composition.

  As shown in the above results, the resist composition of Example 1 had good performance at the same level as the resist compositions of Comparative Examples 1 and 2 with respect to various lithography characteristics.

[Examples 2 to 7, Comparative Example 3]
Each component shown in Table 4 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 4 has the following meaning. Moreover, the numerical value in [] of Table 4 is a compounding quantity (mass part).
(A) -2: a polymer represented by the following chemical formula (A) -2. In chemical formula (A) -2, the number attached to the lower right of () indicates the proportion (mol%) of each structural unit.
(C) -2: a polymer represented by the following chemical formula (C) -2. In chemical formula (C) -2, the number attached to the lower right of () indicates the proportion (mol%) of the structural unit.
(D) -2: Triethanolamine.
In addition, (C) -3, (B) -1 and (S) -1 are the same as those shown in Table 1, and (C) -3 has Mw = 5000 and Mw / Mn = 1.4. It is.

［Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝２．０。］

[Mw = 10000, Mw / Mn = 2.0. ]

［Ｍｗ＝１２０００、Ｍｗ／Ｍｎ＝２．８。］

[Mw = 12000, Mw / Mn = 2.8. ]

The following evaluation was performed using the obtained positive resist composition solution for immersion exposure.
<Hydrophobic evaluation>
The hydrophobicity of the resist film is evaluated by measuring the static contact angle, the falling angle, the receding angle, and the advancing angle (hereinafter referred to as contact angle) of the resist film surface before and after exposure in the following procedure. did.
An organic antireflection film composition “ARC-29A” (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. Thereby, an organic antireflection film having a thickness of 77 nm was formed. Each of the resist compositions of Examples 2 to 7 and Comparative Example 3 is applied onto the antireflection film using a spinner, prebaked (PAB) at 100 ° C. for 60 seconds on a hot plate, and dried. Thus, a resist film having a thickness of 150 nm was formed.
50 μL of water was dropped onto the surface of the resist film (resist film before exposure), and the contact angle and the like were measured using DROP MASTER-700 manufactured by Kyowa Interface Science Co., Ltd.

In addition, a resist film is formed in the same manner as described above, and ArF excimer laser (193 nm) is used using an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, σ = 0.75). Then, open frame exposure (exposure not through a mask) was performed (exposure amount 20 mJ / cm ² ), and the contact angle of the resist film (resist film after exposure) surface was measured in the same manner as described above.
Tables 5 and 6 show measurement results such as the contact angle of the resist film before and after exposure.

  As shown in these results, the resist films obtained using the resist compositions of Examples 2 to 7 were compared with the resist film obtained using the resist composition of Comparative Example 1 before exposure and exposure. Later, the static contact angle, the receding angle and the advancing angle are increased, and the falling angle is decreased. By adding (C) -2 and (C) -3, a highly hydrophobic film can be obtained. Was confirmed.

  Further, when the resolution of the positive resist composition for immersion exposure in Examples 2 to 7 was evaluated by the same method as the above-described lithography characteristic evaluation, an L / S pattern having a line width of 120 nm and a pitch of 240 nm was formed. I was able to.

  As described above, the resist composition of the present invention can form a highly hydrophobic resist film, suppresses substance elution during immersion exposure, and has good lithography characteristics. Therefore, the resist composition for immersion exposure It is suitable as.

It is a figure explaining advancing angle ((theta) ₁ ), receding angle ((theta) ₂ ), and falling angle ((theta) ₃ ).

Claims (12)

Resin component (A) whose alkali solubility is increased by the action of acid, acid generator component (B) which generates acid upon exposure, and resin component (C) which contains a fluorine atom and does not have an acid dissociable group A positive resist composition for immersion exposure comprising:
The resin component (A) has a structural unit (a) derived from acrylic acid and contains a resin (A1) that does not contain a fluorine atom,
A positive resist composition for immersion exposure, wherein the resin component (C) contains a non-main chain cyclic resin (C1) and a main chain cyclic resin (C2).   The positive resist composition for immersion exposure according to claim 1, wherein the resin (C1) has a fluorinated hydroxyalkyl group.   The positive resist composition for immersion exposure according to claim 1, wherein the resin (C1) has a structural unit (a ″) derived from acrylic acid.   The positive resist composition for immersion exposure according to claim 3, wherein the resin (C1) has a structural unit (a0) derived from acrylic acid having a fluorinated hydroxyalkyl group in a side chain portion. The positive resist composition for immersion exposure according to claim 4, wherein the structural unit (a0) includes a structural unit represented by the following general formula (a0-2).

^{Wherein, R 20} is a hydrogen atom, an alkyl group, a halogenated alkyl ^group; a R ^{22, R 23} are each independently a hydrogen atom or a monovalent aliphatic cyclic ^group, the ^{R 22} and ^{R 23} At least one is an aliphatic cyclic group; f is an integer of 0 to 5; b and c are each independently an integer of 1 to 5. ] The positive resist composition for immersion exposure according to any one of claims 1 to 5, wherein the resin (C2) has a structural unit (a'1) represented by the following general formula (I).

[In the formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom, a linear or branched alkyl group, a linear or branched fluorinated alkyl group, or the following general formula (Ia) And at least one of R ^{1 to} R ⁴ is the group (Ia); a is 0 or 1; ]

[In Formula (Ia), Q is a linear or branched alkylene group having 1 to 5 carbon atoms; R ⁵ is a fluorinated alkyl group. ]   7. The positive resist composition for immersion exposure according to claim 1, wherein the content of the resin component (C) is 0.1 to 50% by mass with respect to the resin component (A).   The resin (A1) has a structural unit (a1) derived from an acrylate ester having no fluorine atom and having an acid dissociable, dissolution inhibiting group. A positive resist composition for immersion exposure.   The positive resist for immersion exposure according to claim 8, wherein the resin (A1) further has a structural unit (a2) derived from an acrylate ester having no fluorine atom and containing a lactone-containing cyclic group. Composition.   The liquid immersion according to claim 8 or 9, wherein the resin (A1) further comprises a structural unit (a3) derived from an acrylate ester having no fluorine atom and containing a polar group-containing aliphatic hydrocarbon group. A positive resist composition for exposure.   The positive resist composition for immersion exposure according to any one of claims 1 to 10, comprising a nitrogen-containing organic compound (D).   A step of forming a resist film on a support using the positive resist composition for immersion exposure according to any one of claims 1 to 11, a step of immersion exposure of the resist film, and the resist film A resist pattern forming method including a step of developing and forming a resist pattern.

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