JP2008250157A - Positive resist composition and method for forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition forming a resist pattern with high resolution, and to provide a method for forming the resist pattern. <P>SOLUTION: The positive resist composition contains (A) a resin component whose solubility for an alkali developer solution increases by an action of an acid and (B) an acid generator component generating an acid by exposure. The resin component (A) contains a polymer having a core part represented by general formula (1) and an arm part bonded to the core part and comprising a polymer chain obtained by an anion polymerization method. In formula (1), X represents a specified bonding group which cleaves by an action of an acid; and each of Y and Y' independently represents a C1-C12 alkylene group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a positive resist composition and a resist pattern forming method.

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. A resist material in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist material that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has rapidly progressed due to advances in lithography technology.
As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. In addition, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.

Resist materials are required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions. As a resist material that satisfies such requirements, a chemically amplified resist containing a base resin whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains, as a base resin, a resin that increases solubility in an alkaline developer by the action of an acid and an acid generator. When the acid is generated, the exposed portion becomes soluble in the alkaline developer.
Up to now, as the base resin of chemically amplified resist, polyhydroxystyrene (PHS), which is highly transparent to KrF excimer laser (248 nm), and a resin whose hydroxyl group is protected with an acid dissociable, dissolution inhibiting group (PHS resin) Has been used. However, since the PHS resin has an aromatic ring such as a benzene ring, the transparency to light having a wavelength shorter than 248 nm, for example, 193 nm, is not sufficient. For this reason, a chemically amplified resist having a PHS resin as a base resin component has drawbacks such as low resolution in a process using 193 nm light, for example.
Therefore, as a resist base resin currently used in ArF excimer laser lithography and the like, since it has excellent transparency near 193 nm, a resin (acrylic resin) having a structural unit derived from (meth) acrylic ester is used. Resin) is mainly used (for example, see Patent Document 1).

Such a chemically amplified resist base resin is obtained by radical polymerization of a plurality of types of (meth) acrylic acid ester monomers.
However, the molecular weight distribution [ratio of mass average molecular weight (Mw) and number average molecular weight (Mn): Mw / Mn] of the base resin obtained by the radical polymerization method exceeds 1.5, and it is difficult to control the molecular weight. There are problems such as difficulty in obtaining a resist pattern with high resolution and low yield.

On the other hand, a chemically amplified resist using a base resin having a molecular weight distribution of 1.01-1.50 has been proposed (see Patent Document 2).
JP 2003-241385 A JP 2003-84436 A

However, in recent years, the miniaturization of resist patterns has further progressed, and further improvement in resolution has been demanded for resist patterns formed from conventional chemically amplified positive resist compositions.
In addition, for example, lithography with an electron beam or EUV aims to form a fine pattern of several tens of nanometers. Therefore, it is very important to form a resist pattern with high resolution as the resist pattern size becomes smaller. It becomes.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the positive resist composition and resist pattern formation method which can form a high-resolution resist pattern.

In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention is a positive type containing a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component (B) that generates an acid upon exposure. A resist composition, wherein the resin component (A) includes a core part represented by the following general formula (1), and an arm part that is bonded to the core part and includes a polymer chain obtained by an anionic polymerization method. A positive resist composition comprising a polymer having

［式（１）中、Ｘは酸の作用により解裂する下記一般式（４）〜（７）で表される結合基のいずれかを表し；Ｙ及びＹ’はそれぞれ独立して炭素原子数１〜１２のアルキレン基を表す。］

[In formula (1), X represents any of the linking groups represented by the following general formulas (4) to (7) that are cleaved by the action of an acid; Y and Y ′ each independently represent the number of carbon atoms 1 to 12 alkylene groups are represented. ]

［式（４）〜（７）中、Ｒ_４、Ｒ_５、Ｒ_６、及びＲ_７はそれぞれ独立してハロゲン原子もしくはエポキシ基で置換されていてもよい炭素原子数１〜１２の直鎖状、分枝鎖状、もしくは環状のアルキル基、ハロゲン原子もしくはエポキシ基で置換されていてもよいアリール基、及び水素原子からなる群から選択される一つを表す。Ｒ_８はハロゲン原子もしくはエポキシ基で置換されていてもよい炭素原子数１〜１２の直鎖状、分枝鎖状、もしくは環状のアルキレン基、ハロゲン原子もしくはエポキシ基で置換されていてもよいアリーレン基、及び単結合からなる群から選択される一つを表す。］

[In the formulas (4) to (7), R ₄ , R ₅ , R ₆ and R ₇ are each independently a straight chain having 1 to 12 carbon atoms which may be substituted with a halogen atom or an epoxy group. Represents one selected from the group consisting of a branched or cyclic alkyl group, an aryl group optionally substituted by a halogen atom or an epoxy group, and a hydrogen atom. R ₈ is a linear, branched or cyclic alkylene group which may be substituted with a halogen atom or an epoxy group, an arylene which may be substituted with a halogen atom or an epoxy group It represents one selected from the group consisting of a group and a single bond. ]

  Further, the second aspect of the present invention includes a step of forming a resist film on a support using the positive resist composition of the first aspect, a step of exposing the resist film, and an alkali of the resist film. A resist pattern forming method comprising a step of developing to form a resist pattern.

In the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting the resin component (polymer).
Unless otherwise specified, the “alkyl group” includes linear, branched, and cyclic monovalent saturated hydrocarbon groups.
“Lower alkyl group” means an alkyl group having 1 to 5 carbon atoms.
Unless otherwise specified, the “alkylene group” includes linear, branched, and cyclic divalent saturated hydrocarbon groups.
The “arylene group” means a divalent aromatic group obtained by removing two hydrogen atoms from an aromatic hydrocarbon nucleus.
“Exposure” is a concept that encompasses not only light irradiation but also whole irradiation of radiation such as electron beam irradiation.

  ADVANTAGE OF THE INVENTION According to this invention, the positive resist composition and resist pattern formation method which can form a high-resolution resist pattern can be provided.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid (hereinafter referred to as component (A)), and an acid generator component that generates an acid upon exposure. (B) (hereinafter referred to as component (B)).
In the positive resist composition of the present invention, the component (A) is insoluble in an alkali developer before exposure. When an acid is generated from the component (B) by exposure, the component (A) is generated by the action of the acid. The solubility with respect to the whole alkali developing solution increases, and it changes from alkali-insoluble to alkali-soluble. Therefore, when a resist film obtained by using a positive resist composition is selectively exposed in the formation of a resist pattern, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, alkali development can be performed.

<(A) component>
In the present invention, the component (A) is a polymer having a core part represented by the general formula (1) and an arm part that is bonded to the core part and is made of a polymer chain obtained by an anionic polymerization method (hereinafter referred to as “a part”). , Polymer (A1)).

(Core part)
The core part of the polymer (A1) is represented by the general formula (1).
In the general formula (1), X represents any of the linking groups represented by the general formulas (4) to (7) that are cleaved by the action of an acid.
In the present specification and claims, “cleaved by the action of an acid” means that the bond of the main chain of the polymer (A1) is formed in the core part by the action of an acid generated from the component (B) by exposure. Means to be disconnected.
Of the linking groups represented by the general formulas (4) to (7), the effect of the present invention is good. And the bonding group represented by the general formula (4) is most preferable.

In the general formulas (4) to (7), R ₄ , R ₅ , R ₆ , and R ₇ are each independently a straight chain having 1 to 12 carbon atoms that may be independently substituted with a halogen atom or an epoxy group. It represents one selected from the group consisting of a chain, branched or cyclic alkyl group, an aryl group optionally substituted with a halogen atom or an epoxy group, and a hydrogen atom. Especially, it is preferable that it is a hydrogen atom, and it is especially preferable that all of R < ₄ > and R < ₅ > or R < ₆ > and R < ₇ > are hydrogen atoms.
R ₈ may be substituted with a linear, branched or cyclic alkylene group, a halogen atom or an epoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom or an epoxy group. It represents one selected from the group consisting of an arylene group and a single bond.
Examples of the halogen atom in R _{4 to} R ₈ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Y and Y ′ each independently represents an alkylene group having 1 to 12 carbon atoms.
The alkylene group may be linear or branched. The alkylene group has 1 to 12 carbon atoms, preferably 1 to 10, more preferably 1 to 5, particularly preferably 2 (ethylene group), and most preferably Y and Y ′ are ethylene groups. preferable.

  Preferred specific examples of the core portion of the polymer (A1) are listed below.

(Arm part)
The arm part of the polymer (A1) is composed of a polymer chain bonded to the core part and obtained by an anionic polymerization method.
The polymer chain bonded to the core part is preferably bonded to both ends of the core part. The polymer chains bonded to both ends of the core part may be the same or different from each other at both ends of the core part, and the effects of the present invention are particularly good. Is preferred.
The polymer chain constituting the arm part preferably includes a structural unit derived from a hydroxystyrene derivative (hereinafter referred to as structural unit (a1)).
Moreover, it is preferable that the polymer chain which comprises the said arm part contains the structural unit (henceforth a structural unit (a2)) containing an acid dissociable dissolution inhibiting group.

・ Structural unit (a1)
The structural unit (a1) is a structural unit derived from a hydroxystyrene derivative.
In the present specification and claims, the term “hydroxystyrene derivative” refers to hydroxystyrene and those in which the hydrogen atom at the α-position of hydroxystyrene is substituted with another substituent such as an alkyl group or a halogenated alkyl group. As well as their derivatives.
The α-position (α-position carbon atom) is a carbon atom to which a benzene ring is bonded unless otherwise specified.
“A structural unit derived from a hydroxystyrene derivative” means a structural unit formed by cleavage of an ethylenic double bond of a hydroxystyrene derivative.
As a suitable thing of a structural unit (a1), the structural unit represented by the following general formula (a1-1) can be illustrated.

［式（ａ１−１）中、Ｒは水素原子、低級アルキル基、またはハロゲン化低級アルキル基であり；Ｒ^１１は低級アルキル基であり；ｐは１〜３の整数であり；ｑは０〜２の整数である。］

[In Formula (a1-1), R is a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group; R ¹¹ is a lower alkyl group; p is an integer of 1 to 3; It is an integer of 2. ]

In the general formula (a1-1), the lower alkyl group of R is an alkyl group having 1 to 5 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, Examples thereof include linear or branched alkyl groups such as isobutyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group, and among these, a methyl group is preferable.
The halogenated lower alkyl group of R is a group in which part or all of the hydrogen atoms of the lower alkyl group are substituted with halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). A lower alkyl group is preferable, and a group in which all of the hydrogen atoms are substituted with fluorine atoms is particularly preferable. Specific examples of the fluorinated lower alkyl group include a trifluoromethyl group, a hexafluoroethyl group, a heptafluoropropyl group, and a nonafluorobutyl group.
R is preferably a hydrogen atom or a lower alkyl group, particularly preferably a hydrogen atom or a methyl group.

p is an integer of 1 to 3, preferably 1.
The bonding position of the hydroxyl group may be any of the o-position, m-position and p-position of the phenyl group. When p is 1, the p-position is preferred because it is readily available and inexpensive. When p is 2 or 3, arbitrary substitution positions can be combined.

q is an integer of 0-2. Among these, q is preferably 0 or 1, and is preferably 0 industrially.
As the lower alkyl group for R ^{11, the same as} the lower alkyl group for R ¹¹ can be exemplified.
When q is 1, the substitution position of R ¹¹ may be any of the o-position, m-position, and p-position. When q is 2, arbitrary substitution positions can be combined.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a1) is preferably from 50 to 90 mol%, more preferably from 55 to 85 mol%, more preferably from 60 to 80 mol, based on the total of all structural units constituting the polymer chain as the arm portion. % Is more preferable. Within this range, moderate alkali solubility can be obtained and the balance with other structural units is good.

・ Structural unit (a2)
The structural unit (a2) is a structural unit containing an acid dissociable, dissolution inhibiting group.
In the present specification and claims, “acid dissociation” means dissociation from the polymer chain constituting the arm portion of the polymer (A1) by the action of an acid generated from the component (B) during exposure. Means that.
The “dissolution-inhibiting group” means a group that has an alkali dissolution inhibiting property that renders the entire polymer (A1) insoluble in alkali before dissociation and changes the entire polymer (A1) to alkali-soluble after dissociation. .
The acid dissociable, dissolution inhibiting group in the structural unit (a2) has an alkali dissolution inhibiting property that makes the entire polymer (A1) insoluble in an alkali developer before dissociation, and dissociates by the action of an acid. The solubility of the polymer (A1) as a whole in an alkaline developer is increased, and those proposed so far as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. 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 dissociable, dissolution inhibiting group such as an alkoxyalkyl group is widely known. .
“(Meth) acrylic acid” means either acrylic acid in which a hydrogen atom is bonded to a carbon atom to which a carbonyl group is bonded, or methacrylic acid in which a methyl group is bonded to a carbon atom to which a carbonyl group is bonded. Or both.

Here, the “tertiary alkyl ester” is an ester formed by replacing the hydrogen atom of a carboxy group in (meth) acrylic acid or the like with a chain or cyclic alkyl group, and the carbonyloxy A structure in which the tertiary carbon atom of the chain or cyclic alkyl group is bonded to the oxygen atom at the terminal of the group (—C (O) —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.

The term “aliphatic” in the present specification is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do 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 (a2) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group.
The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Examples of the aliphatic cyclic group include monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes that may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. And groups obtained by removing one or more hydrogen atoms from a polycycloalkane. More 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 and the like can be mentioned. Alternatively, in a structural unit represented by the following general formula (a2 ″), 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（ａ２”）中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６はアルキル基（直鎖状、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である。）を示す。］

[In the formula (a2 ″), 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（ｐ１）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、Ｗは低級アルキル基または脂肪族環式基を表す。］

[In formula (p1), R ¹ ′ and R ² ′ each independently represents a hydrogen atom or a lower alkyl group, n represents an integer of 0 to 3, and W represents a lower alkyl group or an aliphatic cyclic group. To express. ]

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

［式（ｐ１−１）中、Ｒ^１’、ｎ、Ｗはそれぞれ上記と同様である。］

[In formula (p1-1), R ¹ ′, n and W are the same as defined above. ]

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

  Preferable examples of the acetal type acid dissociable, dissolution inhibiting group represented by the general formula (p1-1) include those represented by the following formulas (11) to (22).

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

［式（ｐ２）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。］

[In Formula (p2), R ¹⁷ and R ¹⁸ are each independently a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ is a linear, branched or cyclic alkyl group. . Alternatively, R ¹⁷ and R ¹⁹ may be each independently a linear or branched alkylene group, and the end of R ^{17 and} the end of R ¹⁹ may be bonded to form a ring. ]

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include groups excluding hydrogen atoms. Specific examples thereof 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 a suitable thing of a structural unit (a2), the structural unit represented by the structural unit represented by the following general formula (a2-1), the acrylate ester containing an acid dissociable, dissolution inhibiting group, etc. can be illustrated.

［式（ａ２−１）中、Ｒ、Ｒ^１１、ｑ、Ｒ^１’、ｎ及びＷはそれぞれ上記と同様である。］

[In formula (a2-1), R, R ¹¹ , q, R ¹ ′, n and W are the same as defined above. ]

In the general formula (a2-1), the bonding position of “—O—CHR ¹ ′ —O— (CH ₂ ) _n —W” may be any of the o-position, m-position, and p-position of the phenyl group. The p-position is most preferred because the effects of the present invention are good.

  More specific examples of the structural unit derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group include structural units represented by the following general formulas (a2-11) to (a2-14).

［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；ｍは０または１を表し；Ｒ、Ｒ^１’、Ｒ^２’、ｎ及びＷはそれぞれ上記と同様である。］

[Wherein, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group; m represents 0 or 1; R, R ¹ ′, R ² ′, n and W are the same as defined above. . ]

  In the above formula, X ′ is the same as the above-described tertiary alkyl ester type acid dissociable, dissolution inhibiting group.

Among the above, as the structural unit (a2), a structural unit represented by the general formula (a2-1) is particularly preferable.
Specific examples of the structural unit (a2) are shown below.

  As the structural unit (a2), among the above, at least one selected from the chemical formula (a2-1-1) to the chemical formula (a2-1-4) is preferable because the effects of the present invention are favorable. The chemical formula (a2-1-1) or the chemical formula (a2-1-2) is most preferable.

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) is preferably from 5 to 50 mol%, more preferably from 10 to 40 mol%, further preferably from 15 to 35 mol%, based on the total of all the structural units constituting the polymer chain as the arm portion. preferable. When it is at least the lower limit of the range, a pattern can be obtained when it is a positive resist composition, and when it is at most the upper limit, the balance with other structural units is good.

  The structural unit (a2) may be a structural unit derived from a monomer containing an acid dissociable, dissolution inhibiting group. For example, an alkenylphenol-type polymer having a p-hydroxystyrene (PHS) segment as a main skeleton of an arm part may be used. After the production, a structural unit obtained by introducing an acid dissociable, dissolution inhibiting group into the phenol part may be used.

-Other structural units In addition to the structural unit (a1) and the structural unit (a2), the polymer chain constituting the arm part of the polymer (A1) is further composed of structural units derived from styrene (hereinafter, structural units ( a4))) may be included.
For example, when the structural unit (a4) is included in the polymer chain constituting the arm portion, the solubility in an alkali developer can be adjusted. Moreover, since dry etching tolerance improves, it is preferable.
In this specification, “styrene” is a concept including styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as an alkyl group or a halogenated alkyl group.
“Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.
As a suitable thing of a structural unit (a4), the structural unit represented by the following general formula (a4-1) can be illustrated.

［式（ａ４−１）中、Ｒは前記と同じであり；Ｒ^１２は低級アルキル基であり；ｒは０〜３の整数である。］

[In Formula (a4-1), R is the same as defined above; R ¹² is a lower alkyl group; and r is an integer of 0 to 3. ]

In the general formula (a4-1), R and R ¹² are the same as R and R ¹¹ in the formula (a1-1), respectively.
r is an integer of 0 to 3, preferably 0 or 1, and industrially particularly preferably 0.
When r is 1, the substitution position of R ¹² may be any of the o-position, m-position and p-position of the phenyl group. When r is 2 or 3, arbitrary substitution positions can be combined.

As the structural unit (a4), one type may be used alone, or two or more types may be used in combination.
When the arm part of the polymer (A1) includes the structural unit (a4), the proportion of the structural unit (a4) is preferably 1 to 20 mol% with respect to the total of all the structural units constituting the polymer chain as the arm part. 3 to 15 mol% is more preferable, and 5 to 15 mol% is more preferable. The effect by having a structural unit (a4) is high as it is more than the lower limit of this range, and the balance with another structural unit is also favorable as it is below an upper limit.

Further, the arm part of the polymer (A1) is derived from a structural unit derived from an acrylate ester containing a lactone-containing cyclic group as another structural unit, or an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. Conventionally known as a structural unit, a structural unit derived from an acrylate ester containing an acid non-dissociable aliphatic polycyclic group, and the like used for resist resins for ArF excimer laser, KrF excimer laser, etc. Many are available.
In the present specification, “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent include a lower alkyl group and a halogenated lower alkyl group.
The α-position (α-position carbon atom) of a structural unit derived from an acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and is 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.

In the present invention, the arm part of the polymer (A1) is preferably composed of a polymer chain containing the structural unit (a1) and / or the structural unit (a2). Examples of the arm part (polymer chain) include those containing the structural units (a1) and (a2), those containing the structural units (a1), (a2) and (a4).
As this arm part, what contains the 2 types of structural unit shown by the following general formula (a-11) especially is preferable.

［式中、Ｒは前記と同じであり；ｎ_１は０または１である。］

[Wherein, R is as defined above; n ₁ is 0 or 1; ]

In formula (a-11), R is preferably a hydrogen atom or a methyl group.
The bonding position between adamantane and —CH ₂ —O— (CH ₂ ) _n1 — is preferably the 1- or 2-position of adamantane.
n ₁ is particularly preferably 0.

(Production method of polymer (A1))
The method for producing the polymer (A1) is not particularly limited. For example, an anionic polymerization coupling agent is used as a raw material for providing the core represented by the general formula (1), and the anionic polymerization is performed. The polymer (A1 ′) is synthesized by reacting the coupling agent for use with the polymer (hereinafter referred to as polymer (a)) obtained by the anionic polymerization method providing the arm portion, and the phenol in the polymer (A1 ′) And a method for producing the polymer (A1) by removing all or a part of the protecting groups for protecting the neutral hydroxy group and the like, and preferably introducing an acid dissociable, dissolution inhibiting group.
Such a method is preferable because each reaction can be easily controlled and the structure of the polymer (A1) can be easily controlled.
Hereinafter, the manufacturing method of a polymer (A1) is demonstrated in detail.

In the present invention, it is preferable to use a coupling agent for anionic polymerization as a raw material for providing the core represented by the general formula (1).
Specifically, as the coupling agent for anionic polymerization, the reaction with the polymer (a) providing the arm part is good, and the polymer (A1) can be easily produced. Compounds.

［式（１’）中、Ｘ、Ｙ、及びＹ’はそれぞれ上記と同様であり；Ｚ及びＺ’はそれぞれ独立してハロゲン原子又は下記一般式（３）で表されるエポキシ基を表す。］

[In the formula (1 ′), X, Y and Y ′ are the same as defined above; Z and Z ′ each independently represent a halogen atom or an epoxy group represented by the following general formula (3). ]

［式（３）中、Ｒ_１、Ｒ_２、及びＲ_３はそれぞれ独立して水素原子又はメチル基を表す。］

[In Formula (3), R ₁ , R ₂ , and R ₃ each independently represent a hydrogen atom or a methyl group. ]

In the general formula (1 ′), examples of X, Y, and Y ′ are the same as X, Y, and Y ′ in the general formula (1).
Z and Z ′ each independently represent a halogen atom or an epoxy group represented by the general formula (3). Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. A chlorine atom and a bromine atom are preferable, and a bromine atom is most preferable.
In the present invention, when Z and / or Z ′ in the general formula (1 ′) is a chlorine atom, Y and / or Y ′ bonded thereto is preferably a methylene group.
In addition, when Z and / or Z ′ in the general formula (1 ′) is a bromine atom, Y and / or Y ′ bonded thereto is preferably an alkylene group having 1 to 4 carbon atoms, The alkylene group (ethylene group) of the number 2 is particularly preferable.
In the general formula (3), R ₁ , R ₂ , and R ₃ each independently represent a hydrogen atom or a methyl group.

  Examples of the coupling agent for anionic polymerization represented by the general formula (1 ′) include compounds represented by the following general formula (1′-1).

［式（１’−１）中、Ｙ、Ｙ’、Ｚ、及びＺ’はそれぞれ上記と同じである。］

[In Formula (1′-1), Y, Y ′, Z, and Z ′ are the same as described above. ]

  Specifically, a compound represented by the following chemical formula (1'-1-1) can be given.

  The method for producing the coupling agent for anionic polymerization represented by the general formula (1 ′) is not particularly limited. For example, the above general formula (4) is obtained by reacting paraformaldehyde with a halogen-substituted alcohol. The coupling agent for anionic polymerization which has a coupling group represented by this can be manufactured.

  The polymer (a) that provides the arm portion is, for example, a monomer (hydroxystyrene derivative compound) that provides the structural unit (a1) in the presence of an anionic polymerization initiator, and other structural units that can be further anionically polymerized if desired. It is obtained by anionic polymerization reaction with a monomer that provides

As an anionic polymerization initiator, an alkali metal atom or an organic alkali metal compound can be exemplified.
Examples of the alkali metal atom include lithium, sodium, potassium, cesium and the like.
Examples of the organic alkali metal compound include alkylated products, allylated products, arylated products and the like of the above alkali metal atoms. Specific examples include ethyllithium, n-butyllithium, s-butyllithium, and t-butyllithium. , Ethyl sodium, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, α-methylstyrene sodium dianion, 1,1-diphenylhexyl lithium, 1,1-diphenyl-3-methylpentyl lithium, and the like. .

As an anionic polymerization method for synthesizing the polymer (a) that provides the arm part, a method of dropping an anionic polymerization initiator into a monomer solution or a monomer mixed solution, a monomer solution or a monomer mixed solution in a solution containing an anionic polymerization initiator, Since any of the dropping methods can be performed and the molecular weight and molecular weight distribution can be easily controlled, a method of dropping the monomer solution or the monomer mixed solution into the solution containing the anionic polymerization initiator is preferable.
The anionic polymerization method for synthesizing the polymer (a) is usually preferably performed in an organic solvent under an inert gas atmosphere such as nitrogen or argon at a temperature of -100 to 50 ° C, and -100 to 40 ° C. It is more preferable to carry out under temperature.

Examples of the organic solvent used in the anionic polymerization method for synthesizing the polymer (a) include aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and cyclopentane; benzene, toluene and the like In addition to ethers such as diethyl ether, tetrahydrofuran (THF) and dioxane, organic solvents usually used in anionic polymerization methods such as anisole and hexamethylphosphoramide are exemplified. Hexane and THF are preferred.
These organic solvents can be used singly or as a mixed solvent of two or more.

  When the polymer (a) providing the arm part is a copolymer, any polymer form of a random copolymer, a partial block copolymer, and a complete block copolymer is possible. These can be appropriately synthesized by selecting a method for adding monomers used for polymerization.

The reaction of synthesizing the polymer (A1 ′) by linking the polymer (a) that provides the arm part to the coupling agent for anionic polymerization that provides the core part is performed after the anionic polymerization reaction for synthesizing the polymer (a) is completed. It can carry out by adding the coupling agent for anionic polymerization to this polymerization reaction liquid.
Such a reaction is usually preferably carried out in an organic solvent at a temperature of −100 to 50 ° C., more preferably at a temperature of −70 to 40 ° C. in an inert gas atmosphere such as nitrogen or argon. . Thereby, the polymer (A1 ′) structure is controlled, and a polymer having a narrow molecular weight distribution can be obtained.
In addition, the synthesis reaction of the polymer (A1 ′) can be continuously performed in the organic solvent used in the anionic polymerization reaction for synthesizing the polymer (a) that provides the arm part, and a new solvent is added. The composition may be changed or the solvent may be replaced with another solvent. As the solvent that can be used here, the same organic solvent used in the anionic polymerization reaction for synthesizing the polymer (a) that provides the arm portion can be used.

The reaction for removing the protecting group that protects the phenolic hydroxy group and the like from the polymer (A1 ′) thus obtained is carried out by using alcohols such as methanol and ethanol in addition to the solvents exemplified in the polymerization reaction; acetone and methyl ethyl ketone. , Ketones such as methyl isobutyl ketone (MIBK); polyhydric alcohol derivatives such as methyl cellosolve and ethyl cellosolve; or hydrochloric acid, sulfuric acid, oxalic acid, chloride in the presence of one or more mixed solvents such as water 150 ° C. or higher at room temperature or higher with an acidic reagent such as hydrogen gas, hydrobromic acid, p-toluenesulfonic acid, 1,1,1-trifluoroacetic acid, LiHSO ₄ , NaHSO ₄ or KHSO ₄ as a catalyst. It is preferable to carry out under the following temperature. In this reaction, all or part of the protecting groups protecting the phenolic hydroxy group and the like can be removed by appropriately combining the type and concentration of the solvent, the type and addition amount of the catalyst, and the reaction temperature and reaction time. it can.

In addition, when the structural unit induced | guided | derived from an acrylate ester is contained in the arm part of a polymer (A1), it can derive | lead to a carboxy group by hydrolyzing the ester group of the said structural unit.
This hydrolysis can be carried out by a method known in the art, and for example, can be carried out by acid hydrolysis under the same conditions as those for removing the above-mentioned protecting group. Preferably, the hydrolysis of the ester group is performed simultaneously with the removal of the phenolic hydroxyl group. The polymer (A1) containing a structural unit derived from an acrylate ester thus obtained in the arm part is particularly preferable as a resist material because it has high alkali solubility.

In addition, after removing a protecting group for protecting the phenolic hydroxy group and the like from the polymer (A1 ′), a protecting group such as an acid dissociable dissolution inhibiting group exemplified in the description of the structural unit (a2) is newly introduced. Also good.
Such a protecting group can be introduced by a known method (for example, a method of reacting a protecting group precursor compound having a halogen atom under a basic catalyst).

The polymer (A1) obtained by the above production method can be used without any particular purification, and may be used after purification if necessary.
This purification can be performed by a method usually used in the technical field, for example, by a fractional reprecipitation method. In the fractional reprecipitation method, it is preferable to perform reprecipitation using a mixed solvent of a polymer-soluble solvent and a low solvent. Purification can be performed by dissolving the polymer (A1) in a solvent having high polymer solubility and then adding the solvent having low polymer solubility to precipitate the polymer (A1).

The Mw / Mn of the polymer (A1) is preferably from 1.01 to 3.00, more preferably from 1.01 to 2.00, and even more preferably from 1.01 to 1.50. 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.
The Mn of the polymer (A1) is preferably 1000 to 1000000, more preferably 3000 to 1000000, and further preferably 3500 to 500000. The effect of this invention improves that it is this range.

In the component (A), as the polymer (A1), one type may be used alone, or two or more types may be used in combination.
In addition to the polymer (A1), other polymer compounds known for use in positive resist compositions, such as hydroxystyrene resin, novolak resin, acrylic resin, etc., can be used in combination as component (A). is there.
However, the proportion of the polymer (A1) in the component (A) is preferably 50% by mass or more, more preferably 70% by mass or more, particularly preferably 80% by mass or more, and 100% by mass. % Is most preferred.
In the positive resist composition of the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

<(B) component>
The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, 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.

  As the onium salt acid generator, for example, an acid generator represented by the following general formula (b-0) can be used.

[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 or a halogen atom; A linear or branched alkyl group, a linear or branched alkyl halide group, or a linear or branched alkoxy group; R ⁵³ may have a substituent. A good aryl group; u ″ is an integer from 1 to 3.]

In the 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 fluorine atoms to the total number of fluorine atoms and hydrogen atoms in the fluorinated alkyl group (%)) is preferably 10 to 100%, more preferably 50 In particular, the one in which all hydrogen atoms are substituted with fluorine atoms is preferable because the strength of the acid becomes strong.
R ⁵¹ is most preferably a linear alkyl group or a fluorinated alkyl group.

R ⁵² is 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, more preferably 1 to 4, and particularly 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 anthryl group, and the like. From the viewpoint of the effect of the invention and the 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.

  The acid generator represented by general formula (b-0) can be used alone or in combination of two or more.

  As other onium salt-based acid generators represented by the general formula (b-0), for example, compounds represented by the following general formula (b-1) or (b-2) are also preferably used. It is done.

［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、直鎖状、分岐鎖状または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[Wherein R ¹ ″ to R ³ ″ and R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group; R ⁴ ″ represents a linear, branched or cyclic alkyl group; Or represents a fluorinated alkyl group; at least one of R ¹ ″ to R ³ ″ represents an aryl group, and at least one of R ⁵ ″ to R ⁶ ″ represents an aryl group.]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. 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, a hydroxyl group or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, ethyl group, propyl group, n-butyl group, or 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, linear C1-10, branched or cyclic alkyl group, and the like. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are most preferably a phenyl group or a naphthyl group, respectively.

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. A fluorinated alkyl group (perfluoroalkyl group) is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. It is preferable that all of R ⁵ ″ to R ⁶ ″ are aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
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, Most preferably, it has 3 carbon atoms.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, Has 1 to 7 carbon atoms, more preferably 1 to 3 carbon atoms.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, 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.

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

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

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

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

The anion part of the sulfonium salt having a cation part represented by formula (b-5) or formula (b-6) is not particularly limited, and is the same as the anion part of onium salt-based acid generators proposed so far. May be. Examples of the anion moiety include an anion moiety (R ⁵¹ SO ₃ ⁻ ) of the onium salt acid generator represented by the above general formula (b-0), the above general formula (b-1) or (b-2). Fluorinated alkyl sulfonate ions such as an anion moiety (R ^{4 ″} SO ₃ ⁻ ) of an onium salt acid generator represented by formula; an anion moiety represented by the above general formula (b-3) or (b-4) Among these, a fluorinated alkyl sulfonate ion is preferable, a fluorinated alkyl sulfonate ion having 1 to 4 carbon atoms is more preferable, and a linear perfluoroalkyl sulfonate ion having 1 to 4 carbon atoms. Specific examples include trifluoromethyl sulfonate ion, heptafluoro-n-propyl sulfonate ion, nonafluoro-n-butyl sulfonate ion, and the like. I can get lost.

  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 fluorinated, and 90% or more fluorinated. Particularly preferred.

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

The alkyl group or halogenated alkyl group having no substituent for R ³⁵ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³⁵ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred is the strength of the acid generated. Most 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]), pamphlet of International Publication No. 04/074242, An oxime sulfonate-based acid generator disclosed in Examples 1 to 40) on pages 65 to 85 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, it is particularly 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 of the present invention is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, with respect to 100 parts by mass of the component (A), and 5 to 15 Part by mass is most preferred. 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.

<(D) component>
The positive resist composition of the present invention further contains a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component in order to improve the resist pattern shape, the stability over time, and the like. It is preferable to do.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
“Aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, and the like; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, a trialkylamine having 5 to 10 carbon atoms is more preferable, and tri-n-octylamine is most preferable.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
In the present invention, it is particularly preferable to use a trialkylamine having 5 to 10 carbon atoms as the component (D).
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

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

  The positive resist composition of the present invention may further contain miscible additives as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving coating properties, a dissolution inhibitor, Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added and contained as appropriate.

[(S) component]
The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution, 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: compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate, monomethyl ether, monoethyl of the polyhydric alcohols or the compound having an ester bond Ether alkyl such as ether, monopropyl ether, monobutyl ether or monophenyl ether Derivatives of polyhydric alcohols such as compounds having a propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME) among these]; cyclic ethers such as dioxane, methyl lactate, Esters such as ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, Aromatic organics such as dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene A solvent etc. 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 also 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.
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 positive resist composition of the present invention has an effect that a resist pattern with high resolution can be formed. The reason is not clear, but is presumed as follows.
The positive resist composition of the present invention contains a polymer (A1) having a core part containing a linking group that is cleaved by the action of an acid and an arm part made of a polymer chain obtained by an anionic polymerization method. The polymer (A1) is a monodisperse system in which the polymer chain constituting the arm portion is obtained by an anionic polymerization method, so that the molecular weight control is easy and the molecular weight distribution is narrower than that of a base resin obtained by a radical polymerization method. It is a polymer compound.
In addition, in the polymer (A1), since the bond of the main chain of the polymer (A1) is cleaved by the action of an acid in the bonding group of the core part, the molecular weight distribution of the polymer (A1) in the exposed part is even after exposure. Forms a narrow, monodisperse system. In addition, since the bond of the main chain of the polymer (A1) is cleaved at the bonding group of the core part, the molecular weight of the exposed part is much smaller than the molecular weight of the unexposed part of the polymer (A1), and the alkali development of the exposed part is performed. The solubility in the liquid becomes higher. Furthermore, since the molecular weight of the polymer (A1) is greatly different between the exposed area and the unexposed area, the difference in solubility (so-called contrast) between the exposed area and the unexposed area in the alkaline developer is increased.
For the above reasons, it is presumed that the positive resist composition of the present invention has an effect that a high-resolution resist pattern can be formed.

  Further, according to the positive resist composition of the present invention, it is possible to provide a resist composition that is highly sensitive and particularly suitable for electron beams or EUV.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention includes a step of forming a resist film on a support using the positive resist composition, a step of exposing the resist film, and an alkali developing of the resist film to form a resist pattern The process of carrying out is included.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is applied onto a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90, under a temperature condition of 80 to 150 ° C. For example, an electron beam is selectively exposed through a desired mask pattern using an electron beam drawing machine or the like, and then subjected to PEB (post-exposure heating) for 40 to 120 seconds under a temperature condition of 80 to 150 ° C. For 60 to 90 seconds. Subsequently, this is alkali-development-processed using an alkali developing solution, for example, 0.1-10 mass% tetramethylammonium hydroxide aqueous solution, Preferably, water rinse is carried out using a pure water, and it dries. In some cases, a baking treatment (post-baking) may be performed after the alkali development treatment. In this way, a resist pattern faithful to the mask pattern can be obtained.

The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
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 wavelength used for exposure is not particularly limited, and radiation such as ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, soft X-ray is used. Can be done. The positive resist composition is suitable for KrF excimer laser, ArF excimer laser, electron beam or EUV, and particularly suitable for electron beam or EUV.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

<Resin component (A)>
In Example 1 and Comparative Examples 1 and 2, polymer (A) -1, polymer (A) -2, and polymer (A) -3 used as the component (A) were produced by the following synthesis method.

Production Example 1: Production of polymer (A) -1.
[Production Example 1-1: Synthesis of coupling agent for anionic polymerization providing a core part]
Under a nitrogen atmosphere, 0.8 g of sulfuric acid was added to 2.4 g of paraformaldehyde and 40.0 g of 2-bromoethanol, and the mixture was kept at 100 ° C. for 3 hours with stirring.
Thereafter, these reaction mixtures were cooled to room temperature, neutralized with triethylamine, chloroform was added to the reaction mixture, and the organic layer was washed three times with ion-exchanged water.
Thereafter, anhydrous magnesium sulfate was added to the organic layer for drying, followed by concentration under reduced pressure, and the concentrated mixture was further distilled under reduced pressure to formaldehyde bis (2-bromoethyl) which is a coupling agent for anionic polymerization. ) Acetal 12.2 g (yield: 58%) was obtained.

[Production Example 1-2: Synthesis of monodisperse polymer (a) that provides arm part (polymer chain)]
Under a nitrogen atmosphere, 425.0 g of tetrahydrofuran (hereinafter referred to as THF) was cooled to −60 ° C. Under stirring, 20 mmol of s-butyllithium was added while maintaining −60 ° C., followed by dropwise addition of 75.0 g of p-ethoxyethoxystyrene (PEES) over 40 minutes, and the reaction was further continued for 1 hour.
At this stage, a small amount of the reaction solution was collected from the reaction system, and after stopping the reaction with methanol, analysis was performed by gel permeation chromatography (hereinafter referred to as GPC). As a result, the obtained monodisperse polymer (a) was It was confirmed that Mn = 3500 and Mw / Mn = 1.08 in terms of polystyrene.

[Production Example 1-3: Reaction between coupling agent for anionic polymerization and monodisperse polymer (a)]
Next, while maintaining the reaction system at −60 ° C., 3.0 g of formaldehyde bis (2-bromoethyl) acetal obtained in Production Example 1-1 was added dropwise over 10 minutes, and the reaction was further continued for 1 hour.
Thereafter, methanol was added to the reaction system to stop the reaction, and then analysis by GPC was performed to confirm that a monodispersed polymer (A1 ′) with Mn = 5900 and Mw / Mn = 1.09 was obtained in terms of polystyrene. did.

[Production Example 1-4: Hydrolysis of monodisperse polymer (A1 ′) (removal of protecting group on arm portion)]
Methyl isobutyl ketone (hereinafter referred to as MIBK) was added to the polymerization solution obtained in Production Example 1-3, and the organic layer was washed twice with ion-exchanged water. Substitution was carried out with a propylene glycol monomethyl ether (PGME) solution to a mass%.
To 100 parts by mass of this solution, 1 part by mass of oxalic acid dihydrate and 3 parts by mass of ion-exchanged water were added and heated to 50 ° C. The reaction was further continued for 2 hours while maintaining 50 ° C. with stirring.
In this reaction, ¹³ C-NMR of the polymer before and after the reaction was measured, and the results were compared. After the reaction, the absorption derived from PEES observed in the vicinity of 117 ppm disappeared, and the absorption derived from p-hydroxystyrene was newly observed in the vicinity of 115 ppm.
Moreover, when GPC was measured about the polymer after reaction, the monodispersed polymer of Mn = 3000 and Mw / Mn = 1.17 was obtained in polystyrene conversion, and the change in the peak shape of GPC was not seen before and after reaction.
From the above results, the hydrolysis reaction proceeds in the ethoxy group in the structural unit derived from PEES, and an alkenylphenol type polymer having a p-hydroxystyrene (hereinafter referred to as PHS) segment as the main skeleton of the arm part is obtained. It was confirmed that the —O—CH ₂ —O— bond introduced into the core of the polymer was retained.
Next, MIBK was added to the reaction system, and the organic layer was washed with ion-exchanged water three times. Thereafter, the organic layer was concentrated under reduced pressure, diluted with isopropanol (hereinafter referred to as IPA), and poured into a large amount of ion-exchanged water to precipitate a polymer.
After filtration, vacuum drying was performed at 40 ° C. for 100 hours to obtain 41.9 g (yield: 89%) of a white powdery polymer.

[Production Example 1-5: Introduction of methoxyadamantyl group]
Under a nitrogen atmosphere, 30.0 g of the polymer obtained in Production Example 1-4 was dissolved in 270.0 g of THF. Thereafter, 2.6 g of a 60% by mass sodium hydride solution was added, and the mixture was kept at room temperature for 1 hour with stirring. Thereafter, 12.5 g of 2-chloromethoxyadamantane was added dropwise over 1 hour, and the reaction was further continued at room temperature for 20 hours.
After ion-exchanged water was added to the reaction system to stop the reaction, ethyl acetate was added to the reaction solution, the organic layer was washed with an oxalic acid aqueous solution, and further washed with ion-exchanged water three times.
Thereafter, the organic layer was replaced with a propylene glycol monomethyl ether acetate (PGMEA) solution by a concentration operation under reduced pressure.
When the obtained polymer (A) -1 was measured by ¹³ C-NMR, absorption derived from a unit in which a methoxyadamantyl group was newly introduced into the PHS unit (hereinafter referred to as PHS-MOAd). Were observed in the vicinity of 82 ppm, 93 ppm, and 116 ppm, respectively.
Moreover, the ratio of a PHS unit and PHS-MOAd was 75/25 (molar ratio).
Furthermore, when GPC measurement was performed on the obtained polymer (A) -1, it was confirmed that the result was a monodisperse polymer with Mn = 3900 and Mw / Mn = 1.21 in terms of polystyrene, and methoxyadamantyl. There was no change in the GPC peak shape before and after the introduction of the group.
From the above results, an alkenylphenol-type polymer having the PHS / PHS-MOAd segment as the main skeleton of the arm part is obtained, and the —O—CH ₂ —O— bond (acetal bond) introduced into the core part of the polymer is obtained. ) Was confirmed to be retained.

  The structure of polymer (A) -1 produced by the above synthesis method is shown below. In the following chemical formula, the symbol attached to the lower right of () is the ratio of each constituent unit to the total of all constituent units constituting the polymer chain that is the arm part of the polymer (A) -1 (mol%; composition ratio). And calculated by carbon NMR.

［（ａ１１＋ａ１２）／（ａ２１＋ａ２２）＝７５／２５（モル比）；Ｍｎ＝３９００，Ｍｗ／Ｍｎ＝１．２１］

[(A11 + a12) / (a21 + a22) = 75/25 (molar ratio); Mn = 3900, Mw / Mn = 1.21]

Production Example 2: Production of Polymer (A) -2 PGMEA was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer under a nitrogen atmosphere, and the temperature of the hot water bath was increased to 80 ° C. while stirring. Raised. Next, a monomer charged with 2,2′-azobisisobutyronitrile (AIBN) as a polymerization initiator and monomer (1) / monomer (2) = 3/1 (molar ratio) represented by the following chemical formula: The monomer PGMEA solution was dropped into the flask over 6 hours at a constant rate using a dropping device, and then held at 80 ° C. for 1 hour. Thereafter, the reaction solution was returned to room temperature. Subsequently, the obtained reaction solution was added dropwise to about 30 times amount of methanol with stirring to obtain a colorless precipitate. The resulting precipitate was filtered off, and the precipitate was washed in about 30 times the amount of methanol used for the monomer used for the polymerization. Then, this precipitate was filtered off and dissolved in THF, and then an 80% by mass hydrazine aqueous solution was added dropwise to the solution, followed by stirring at 25 ° C. for 1 hour. After completion of the reaction, the mixture was dropped into a large amount of water to obtain a precipitate. The precipitate was separated by filtration, washed, and dried under reduced pressure at 50 ° C. for about 40 hours to obtain polymer (A) -2.
As a result of analysis by GPC, it was confirmed that the obtained polymer (A) -2 had Mn = 7000 and Mw / Mn = 1.7 in terms of polystyrene. Further, the composition ratio (molar ratio) was calculated by carbon NMR.

  The structure of the polymer (A) -2 produced in Production Example 2 is shown below.

［ａ１３／ａ２３＝７５／２５（モル比）］

[A13 / a23 = 75/25 (molar ratio)]

Production Example 3: Production of polymer (A) -3 10 g of poly-4-hydroxystyrene (Mw = 4000, Mw / Mn = 1.1) was dissolved in 100 ml of THF, and 0.92 g of sodium hydride. Was added. 4.37 g of adamantoxymethyl chloride was added to the solution and stirred at room temperature for 20 hours. After stirring, water was added to stop the reaction, and the mixture was concentrated. Thereafter, the mixture was diluted with 400 ml of water, extracted three times with 100 ml of ethyl acetate, and washed with hydrochloric acid, saturated NaHCO ₃ aqueous solution, and saturated NaCl aqueous solution. The resulting solution was concentrated, purified by reprecipitation using an ethyl acetate-n heptane system, and dried to obtain a white solid. As a result of analysis by GPC, it was confirmed that the obtained polymer (A) -3 had Mn = 4200 and Mw / Mn = 1.1 in terms of polystyrene. The composition ratio (molar ratio) was calculated by carbon NMR and proton NMR.

  The structure of polymer (A) -3 produced in Production Example 3 above is shown below.

［ａ１４／ａ２４＝７５／２５（モル比）］

[A14 / a24 = 75/25 (molar ratio)]

<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 [] is a compounding quantity (mass part).

(B) -1: Triphenylsulfonium nonafluorobutanesulfonate.
(D) -1: tri-n-octylamine.
(E) -1: salicylic acid.
(S) -1: PGMEA.

[Sensitivity / Resolution]
The resolution was evaluated using the obtained positive resist composition.
The positive resist composition of each example was uniformly applied on an 8-inch silicon substrate that had been subjected to hexamethyldisilazane (HMDS) treatment at 90 ° C. for 36 seconds using a spinner. Then, a baking process (PAB) was performed for 90 seconds to form a resist film (film thickness 100 nm).
The resist film was drawn (exposure) at an acceleration voltage of 70 kV using an electron beam lithography machine HL-800D (VSB) (manufactured by Hitachi), and baked (PEB) at the temperatures shown in Table 2 for 90 seconds. ) And development for 60 seconds using a 2.38 mass% aqueous solution (23 ° C.) of tetramethylammonium hydroxide (TMAH), followed by rinsing with pure water for 15 seconds to obtain line and space (L / S) A pattern was formed.
At this time, the exposure amount (Eop; μC / cm ² ) at which a 100 nm L / S pattern was formed at 1: 1 was determined. The results are shown in Table 2.
The limiting resolution (nm) in the Eop was determined using a scanning electron microscope S-9220 (manufactured by Hitachi). The results are shown in Table 2 as “resolution”.

  From the results in Table 2, it was confirmed that the positive resist composition of Example 1 according to the present invention was excellent in resolution as compared with the positive resist compositions of Comparative Examples 1 and 2.

Claims (6)

A positive resist composition comprising a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure,
The resin component (A) contains a polymer having a core part represented by the following general formula (1) and an arm part that is bonded to the core part and is made of a polymer chain obtained by an anionic polymerization method. A positive resist composition characterized by the above.

[In formula (1), X represents any of the linking groups represented by the following general formulas (4) to (7) that are cleaved by the action of an acid; Y and Y ′ each independently represent the number of carbon atoms 1 to 12 alkylene groups are represented. ]

[In the formulas (4) to (7), R ₄ , R ₅ , R ₆ and R ₇ are each independently a straight chain having 1 to 12 carbon atoms which may be substituted with a halogen atom or an epoxy group. Represents one selected from the group consisting of a branched or cyclic alkyl group, an aryl group optionally substituted by a halogen atom or an epoxy group, and a hydrogen atom. R ₈ is a linear, branched or cyclic alkylene group which may be substituted with a halogen atom or an epoxy group, an arylene which may be substituted with a halogen atom or an epoxy group It represents one selected from the group consisting of a group and a single bond. ]   The positive resist composition according to claim 1, wherein the arm portion includes a structural unit derived from a hydroxystyrene derivative.   The positive resist composition according to claim 1, wherein the arm portion includes a structural unit including an acid dissociable, dissolution inhibiting group. The positive resist composition according to claim 3, wherein the acid dissociable, dissolution inhibiting group is an acetal type acid dissociable, dissolution inhibiting group represented by the following general formula (p1-1).

[In formula (p1-1), R ¹ ′ represents a hydrogen atom or a lower alkyl group; n represents an integer of 0 to 3; W represents a lower alkyl group or an aliphatic cyclic group. ]   Furthermore, the positive resist composition as described in any one of Claims 1-4 containing a nitrogen-containing organic compound (D).   A step of forming a resist film on a support using the positive resist composition according to claim 1, a step of exposing the resist film, and an alkali developing of the resist film to form a resist A resist pattern forming method comprising a step of forming a pattern.