JP2009193041A - Positive resist composition and method of forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition which is used as a second resist composition in the formation of a resist pattern through double patterning, and to provide a method of forming a resist pattern. <P>SOLUTION: The method of forming a resist pattern includes: applying the positive resist composition on a support on which a first resist pattern formed of a first resist film comprising a positive resist composition is formed to form a second resist film; and selectively exposing the second resist film and alkali-developing the second resist film to form a resist pattern, wherein the positive resist composition used to form the second resist film is prepared by dissolving a resin component (A) having a structural unit of specific structures, which exhibits increased solubility in an alkali developing solution under action of acid and an acid-generator component (B) which generates acid upon exposure in an organic solvent (S) which does not dissolve the first resist film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is suitably used for the second resist composition in a double patterning process in which the first patterning is performed using the first resist composition and the second patterning is performed using the second resist composition. The present invention relates to a positive resist composition and a resist pattern forming method.

A technology (pattern formation technology) that forms a fine pattern on a substrate and processes the lower layer of the pattern by etching using this as a mask has been widely adopted for IC creation in the semiconductor industry, and has received great attention. ing.
The fine pattern is usually made of an organic material, and is formed by a technique such as a lithography method or a nanoimprint method. For example, in a lithography method, a resist film made of a resist composition containing a base material component such as a resin is formed on a support such as a substrate, and a mask in which a predetermined pattern is formed on the resist film (mask A process of forming a resist pattern having a predetermined shape on the resist film is performed by performing selective exposure with radiation such as light and electron beam via a pattern and performing development. And a semiconductor element etc. are manufactured through the process of processing a board | substrate by an etching using the said resist pattern as a mask.
A resist composition in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist composition 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, pattern miniaturization is rapidly progressing due to the advancement of 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. Lithography using an ArF excimer laser enables pattern formation with a resolution of 45 nm. Further, in order to further improve the resolution, studies have been made on F ₂ excimer lasers having a shorter wavelength than these excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like.
The resist composition is 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 composition satisfying such requirements, a chemically amplified resist composition containing a base material component whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. (For example, see Patent Document 1). For example, a positive chemically amplified resist usually contains, as a base material component, a resin whose solubility in an alkaline developer is increased by the action of an acid. When a resist pattern is formed, an acid is generated from an acid generator by exposure. When it occurs, the exposed part becomes soluble in the alkaline developer.
In addition, as a base resin for chemically amplified resist, polyhydroxystyrene (PHS) having high transparency around 248 nm and its hydroxyl group are used as a base resin for resist (KrF resist) mainly used in KrF excimer laser lithography and the like. Resins protected with acid dissociable, dissolution inhibiting groups (PHS resins) and the like. On the other hand, as a base resin for a resist (ArF resist) used in ArF excimer laser lithography and the like, a resin having a structural unit derived from (meth) acrylic acid ester in the main chain because of excellent transparency near 193 nm (Acrylic resin) is mainly used.

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

Recently, as a newly proposed lithography technique, there is a double patterning process in which a resist pattern is formed by performing patterning twice or more (see, for example, Non-Patent Documents 2 to 3).
According to this double patterning process, for example, after forming a first resist pattern by patterning using a first resist composition on a support, the support on which the first resist pattern is formed Furthermore, it is considered that a resist pattern having a higher resolution than that formed by one patterning can be formed by patterning using the second resist composition.
JP 2003-241385 A Proceedings of SPIE, 5754, 119-128 (2005). Proceedings of SPIE, 5256, 985-994 (2003). Proceedings of SPIE, 6153, 615301-1-19 (2006).

In the double patterning process as described above, the first resist pattern is easily affected when the second resist composition is applied. For this reason, for example, a part or all of the first resist pattern is dissolved by the solvent of the second resist composition, resulting in film loss or the like, and the shape of the first resist pattern is damaged. There are problems that the resist composition dissolves, so-called mixing occurs, and a good resist pattern cannot be formed.
It is considered that such a problem can be avoided by using a resist composition dissolved in a solvent in which the first resist pattern is difficult to dissolve as the second resist composition. Therefore, conventionally, when a positive resist composition is used as the first resist composition, a positive resist composition such as an alcohol solvent or an ether organic solvent having no hydroxyl group is used as the second resist composition. Negative resist compositions having good solubility in organic solvents having low compatibility with the resist composition have been mainly used.
On the other hand, as a second resist composition, when using a positive resist composition as in the first resist composition, it is necessary to protect the first resist pattern using a freezing agent or the like, There are problems in that the number of steps is larger than in the case of using a negative resist composition and workability is inferior. Currently, acrylic resins used as the base resin for ArF positive resists are organic solvents such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone, 2-heptanone, and ethyl lactate (EL). This is because they are often used as dissolved positive resist compositions, and when these positive resist compositions are applied directly onto the first resist pattern, the first resist pattern is dissolved.

  The present invention has been made in view of the above circumstances, and can be used as a second resist composition in the formation of a resist pattern by double patterning using a positive resist composition as the first resist composition. It is an object of the present invention to provide a positive resist composition and a resist pattern forming method.

The present inventors propose the following means in order to solve the above problems.
That is, the first aspect of the present invention includes a step of applying a positive resist composition on a support to form a first resist film, and selectively exposing the first resist film to form an alkali. A step of developing to form a first resist pattern, a step of applying a positive resist composition on the support on which the first resist pattern is formed, and forming a second resist film; A positive resist used for forming the second resist film in a positive resist pattern forming method including a step of selectively exposing the second resist film and forming a resist pattern by alkali development. A 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, are dissolved in an organic solvent (S).
The organic solvent (S) is an organic solvent that does not dissolve the first resist film,
The resin component (A) includes a structural unit (a0-1) represented by the following general formula (a0-1) and a structural unit (a0-2) represented by the following general formula (a0-2). A positive resist composition characterized by comprising a positive resist composition characterized by comprising:

［式（ａ０−１）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；Ｙ^１は脂肪族環式基であり；Ｚは第３級アルキル基含有基またはアルコキシアルキル基であり；ａは１〜３の整数であり、ｂは０〜２の整数であり、かつａ＋ｂ＝１〜３であり；ｃ、ｄ、ｅはそれぞれ独立して０〜３の整数である。式（ａ０−２）中、Ｒは水素原子、ハロゲン原子、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；Ｙ^３はアルキレン基または脂肪族環式基であり；ｇ、ｈはそれぞれ独立して０〜３の整数であり；ｉは１〜３の整数である。］

[In formula (a0-1), R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Y ¹ represents an aliphatic cyclic group; Z represents a tertiary alkyl group-containing group or an alkoxyalkyl group. A is an integer of 1 to 3, b is an integer of 0 to 2, and a + b = 1 to 3; c, d, and e are each independently an integer of 0 to 3. In the formula (a0-2), R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; Y ³ is an alkylene group or an aliphatic cyclic group; g and h are each independently I is an integer from 0 to 3; i is an integer from 1 to 3; ]

  The second aspect of the present invention includes a step of applying a positive resist composition on a support to form a first resist film, selectively exposing the first resist film, A step of developing to form a first resist pattern, and applying the positive resist composition of the first aspect on the support on which the first resist pattern is formed, to form a second resist film A resist pattern forming method comprising: a step of forming a resist pattern; and a step of selectively exposing the second resist film and performing alkali development to form a resist pattern.

Here, in the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer, copolymer).
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
“Aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do not have aromaticity.
“Exposure” is a concept that includes general irradiation of radiation.
“(Meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position.
“(Meth) acrylic acid ester means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.
“(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.

  According to the present invention, in the double patterning process in which the first patterning is performed using the first resist composition and the second patterning is performed using the second resist composition, the first resist composition is used. Thus, it is possible to provide a positive resist composition and a resist pattern forming method capable of forming a resist pattern by double patterning without dissolving the first resist pattern formed in this way.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a step of coating a positive resist composition on a support to form a first resist film, and selectively exposing the first resist film to alkali development. Forming a first resist pattern, applying a positive resist composition on the support on which the first resist pattern is formed, and forming a second resist film; In a positive resist pattern forming method including a step of selectively exposing the second resist film and performing alkali development to form a resist pattern, the second resist film is used to form the second resist film.
The description of each step in the resist pattern forming method is the same as the description of each step in the resist pattern forming method of the present invention described later.

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)) is dissolved in the organic solvent (S),
The organic solvent (S) is an organic solvent that does not dissolve the first resist film,
The resin component (A) includes a structural unit (a0-1) represented by the following general formula (a0-1) and a structural unit (a0-2) represented by the following general formula (a0-2). It is characterized by having.
In the positive resist composition of the present invention, the component (A) is insoluble in an alkali developer before exposure, and when an acid generated from the component (B) by exposure acts, an acid dissociable, dissolution inhibiting group. Dissociates, whereby the solubility of the entire component (A) in the alkali developer increases, and the alkali-insoluble is changed 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, a resist pattern can be formed by alkali development.

<(A) component>
In the present invention, the component (A) includes the structural unit (a0-1) represented by the general formula (a0-1) and the structural unit (a0-2) represented by the general formula (a0-2). And have.
Both the structural unit (a0-1) and the structural unit (a0-2) are structural units derived from an acrylate ester.
Here, in the present specification and claims, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include not only acrylic acid esters in which a hydrogen atom is bonded to the α-position carbon atom, but also those in which a substituent (an atom or group other than a hydrogen atom) is bonded to the α-position carbon atom. 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.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
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.

・ Structural unit (a0-1)
In general formula (a0-1), R represents a hydrogen atom, a lower alkyl group, or a halogenated lower alkyl group.
The lower alkyl group or halogenated lower alkyl group for R is the same as the lower alkyl group or halogenated lower alkyl group which may be bonded to the α-position of the acrylate ester. Among them, R is preferably a hydrogen atom or a methyl group.

In general formula (a0-1), Y ¹ represents an aliphatic cyclic group.
Here, in the present specification and claims, the “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a0-1) 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 structure of the basic ring (aliphatic ring) excluding the substituent of the “aliphatic cyclic group” is not limited to being a ring composed of carbon and hydrogen (hydrocarbon ring), but is a hydrocarbon ring. It is preferable. The “hydrocarbon ring” may be either saturated or unsaturated, but is usually preferably saturated.
The aliphatic cyclic group may be either a polycyclic group or a monocyclic group. Examples of the aliphatic cyclic group include monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. And a group obtained by removing two or more hydrogen atoms from a polycycloalkane. More specifically, monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing two or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane are listed. .
The aliphatic cyclic group in the structural unit (a0-1) is preferably a polycyclic group, and among them, a group obtained by removing two or more hydrogen atoms from adamantane is preferable.

In the general formula (a0-1), Z represents a tertiary alkyl group-containing group or an alkoxyalkyl group.
Here, in the present specification and claims, the “tertiary alkyl group” refers to an alkyl group having a tertiary carbon atom. As described above, the “alkyl group” represents a monovalent saturated hydrocarbon group, and includes a chain (straight chain or branched chain) alkyl group and an alkyl group having a cyclic structure.
The “tertiary alkyl group-containing group” refers to a group containing a tertiary alkyl group in its structure. The tertiary alkyl group-containing group may be composed only of a tertiary alkyl group, or may be composed of a tertiary alkyl group and another atom or group other than the tertiary alkyl group. .
Examples of the “atom or group other than the tertiary alkyl group” that constitutes the tertiary alkyl group-containing group together with the tertiary alkyl group include a carbonyloxy group, a carbonyl group, an alkylene group, and an oxygen atom. .

Examples of the tertiary alkyl group-containing group for Z include a tertiary alkyl group-containing group having no cyclic structure, a tertiary alkyl group-containing group having a cyclic structure, and the like.
The tertiary alkyl group-containing group not having a cyclic structure is a group containing a branched tertiary alkyl group as the tertiary alkyl group and having no cyclic structure in the structure.
Examples of the branched tertiary alkyl group include groups represented by the following general formula (I).

In formula (I), R ^{21 to} R ²³ are each independently a linear or branched alkyl group. 1-5 are preferable and, as for carbon number of this alkyl group, 1-3 are more preferable.
Moreover, it is preferable that the total carbon number of group represented by general formula (I) is 4-7, It is more preferable that it is 4-6, It is most preferable that it is 4-5.
Preferred examples of the group represented by the general formula (I) include a tert-butyl group and a tert-pentyl group, and a tert-butyl group is more preferable.

Examples of the tertiary alkyl group-containing group having no cyclic structure include the above-described branched tertiary alkyl group; the above-described branched tertiary alkyl group is a linear or branched alkylene group A tertiary alkyl group-containing chain alkyl group bonded to the above; a tertiary alkyloxycarbonyl group having the branched tertiary alkyl group described above as the tertiary alkyl group; And tertiary alkyloxycarbonylalkyl groups having a branched tertiary alkyl group.
The alkylene group in the tertiary alkyl group-containing chain alkyl group is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and still more preferably an alkylene group having 2 to 2 carbon atoms.
Examples of the chain-like tertiary alkyloxycarbonyl group include a group represented by the following general formula (II). ^R 21 ^{to R 23} in the formula (II) is the same as ^R 21 ^{to R 23} in general formula (I). The chain-like tertiary alkyloxycarbonyl group is preferably a tert-butyloxycarbonyl group (t-boc) or a tert-pentyloxycarbonyl group.

Examples of the chain-like tertiary alkyloxycarbonylalkyl group include a group represented by the following general formula (III). ^R 21 ^{to R 23} in the formula (III) are the same as ^R 21 ^{to R 23} in general formula (I). f is an integer of 1 to 3, and 1 or 2 is preferable. As the chain-like tertiary alkyloxycarbonylalkyl group, a tert-butyloxycarbonylmethyl group and a tert-butyloxycarbonylethyl group are preferable.
Among these, the tertiary alkyl group-containing group having no cyclic structure is preferably a tertiary alkyloxycarbonyl group or a tertiary alkyloxycarbonylalkyl group, more preferably a tertiary alkyloxycarbonyl group. Most preferred is a tert-butyloxycarbonyl group.

The tertiary alkyl group-containing group having a cyclic structure is a group having a tertiary carbon atom and a cyclic structure in the structure.
In the tertiary alkyl group-containing group having a cyclic structure, the cyclic structure preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and more preferably 6 to 10 carbon atoms constituting the ring. Most preferred. Examples of the cyclic structure include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Preferable 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 tertiary alkyl group-containing group having a cyclic structure include a group having the following group (1) or (2) as a tertiary alkyl group.
(1) A group in which a linear or branched alkyl group is bonded to a carbon atom constituting a ring of a cyclic alkyl group (cycloalkyl group), and the carbon atom is a tertiary carbon atom.
(2) A group in which an alkylene group having a tertiary carbon atom (branched alkylene group) is bonded to the carbon atom constituting the ring of the cycloalkyl group.

The linear or branched alkyl group in the group (1) preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. .
Examples of the group (1) include a 2-methyl-2-adamantyl group, a 2-ethyl-2-adamantyl group, a 1-methyl-1-cycloalkyl group, and a 1-ethyl-1-cycloalkyl group.

In the above (2), the cycloalkyl group to which the branched alkylene group is bonded may have a substituent. Examples of the substituent include a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (═O), and the like.
Examples of the group (2) include groups represented by the following chemical formula (IV).

In the formula (IV), R ²⁴ is a cycloalkyl group which may or may not have a substituent. Examples of the substituent that the cycloalkyl group may have include a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (═O).
R ²⁵ and R ²⁶ are each independently a linear or branched alkyl group, and examples of the alkyl group include the same alkyl groups as R ^{21 to} R ²³ in the formula (I). It is done.

  Examples of the alkoxyalkyl group for Z include groups represented by the following general formula (V).

In the formula, R ⁴¹ is a linear, branched or cyclic alkyl group.
When R ⁴¹ 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 ⁴¹ 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. For example, one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group And the like except for. 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. . Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.
^R42 is a linear or branched alkylene group. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 to 2 carbon atoms.
As the alkoxyalkyl group for Z, a group represented by the following general formula (VI) is particularly preferable.

In the formula (VI), R ⁴¹ is the same as described above, and R ⁴³ and R ⁴⁴ are each independently a linear or branched alkyl group or a hydrogen atom.
In R ⁴³ and R ⁴⁴ , 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, one of R ⁴³ and R ⁴⁴ is preferably a hydrogen atom and the other is a methyl group.

  Among these, as Z, a tertiary alkyl group-containing group is preferable, a group represented by the general formula (II) is more preferable, and a tert-butyloxycarbonyl group (t-boc) is most preferable.

In the general formula (a0-1), a is an integer of 1 to 3, b is an integer of 0 to 2, and a + b = 1 to 3.
a is preferably 1.
b is preferably 0.
a + b is preferably 1.
c is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.
d is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.
e is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.

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

［式中、Ｒ，Ｚ，ｂ，ｃ，ｄ，ｅは前記と同じである。］

[Wherein R, Z, b, c, d and e are the same as described above. ]

  The monomer for deriving the structural unit (a0-1) is, for example, a compound represented by the following general formula (a0-1 ′) (an acrylate ester containing an aliphatic cyclic group having 1 to 3 alcoholic hydroxyl groups) ) Can be synthesized by protecting some or all of the hydroxyl groups with a tertiary alkyl group-containing group or alkoxyalkyl group using a known method.

［式中、Ｒ，Ｙ^１，ａ，ｂ，ｃ，ｄ，ｅは前記と同じである。］

[Wherein, R, Y ¹ , a, b, c, d, and e are the same as described above. ]

As the structural unit (a0-1), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a0-1) in the component (A) is preferably 1 to 40 mol%, and preferably 5 to 40 mol%, based on the total of all the structural units constituting the component (A). More preferably, it is more preferably 15 to 40 mol%, and most preferably 20 to 40 mol%. By setting it to the lower limit value or more, the solubility in organic solvents is improved, and when it is the upper limit value or less, the balance with other structural units is good.

・ Structural unit (a0-2)
Examples of R in the general formula (a0-2) include the same as R in the formula (a0-1).
Examples of the alkylene group for Y ³ include alkylene groups having 1 to 10 carbon atoms.
As the aliphatic cyclic group for Y ^3, the same aliphatic cyclic groups as those described above for Y ¹ in formula (a0-1) can be used. Y ³ preferably has the same basic ring (aliphatic ring) structure as Y ¹ .
g is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.
h is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.
i is an integer of ˜3, preferably 1.

As the structural unit (a0-2), a structural unit represented by general formula (a0-2-1) shown below is particularly preferable. Among them, one of i — (CH ₂ ) _h —OH is It is preferably bonded to the 3-position of the 1-adamantyl group.

［式中、Ｒ，ｇ，ｈ，ｉは前記と同じである。］

[Wherein R, g, h and i are the same as described above. ]

As the structural unit (a0-2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a0-2) in the component (A) is preferably 1 to 35 mol%, and preferably 5 to 30 mol%, based on the total of all the structural units constituting the component (A). More preferably, it is more preferably 10 to 30 mol%, and most preferably 20 to 30 mol%. By setting it to the lower limit value or more, the cross-sectional shape is highly rectangular, and a resist pattern having a good shape can be formed. If the upper limit value or less, the balance with other structural units is good.

・ Structural unit (a1)
The component (A) preferably has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, in addition to the structural unit (a0-1) and the structural unit (a0-2). .
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire component (A) insoluble in an alkali developer before dissociation, and dissociates with an acid. This increases the solubility of the entire component in an alkaline developer, and those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. 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. . The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

“Aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-pentyl group, and a tert-heptyl group. .

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

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

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

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹⁵ and R ¹⁶ may be alkyl groups (both linear and branched, preferably 1 to 5 carbon atoms). Is). ]

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

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

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

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

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

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

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

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

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

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group. In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include a group excluding a hydrogen atom. Specific examples 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 the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-0-1) and structural units represented by the following general formula (a1-0-2): Is preferably used.

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

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

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

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

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

In general formula (a1-0-2), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 10 carbon atoms or a divalent aliphatic cyclic group, and a group in which two or more hydrogen atoms are removed is used as the aliphatic cyclic group. Except for the above, the same “aliphatic cyclic group” as described above can be used.
When Y ² is an alkylene group having 1 to 10 carbon atoms, it is more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. .
When Y ² is a divalent aliphatic cyclic group, a group in which two or more hydrogen atoms have been removed from cyclopentane, cyclohexane, norbornane, isobornane, adamantane, tricyclodecane, or tetracyclododecane is particularly preferable. .

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

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

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

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

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

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Among these, the structural unit represented by general formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) and (a1-1-35) to (a1- It is more preferable to use at least one selected from the group 1-41).
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formulas (a1-1-1) to (a1-1-4) The following general formula (a1-1-02) including the structural units of formulas (a1-1-35) to (a1-1-41) is also preferable.

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

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹¹ represents a lower alkyl group. ]

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

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹² represents a lower alkyl group. h represents an integer of 1 to 3. ]

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

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

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

・ Structural unit (a2)
Component (A) is an acrylic acid containing a lactone-containing cyclic group in addition to the structural unit (a0-1), the structural unit (a0-2), and the structural unit (a1) as long as the effects of the present invention are not impaired. The structural unit (a2) derived from ester may be included.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
When the lactone cyclic group of the structural unit (a2) is used for forming a resist film, the lactone cyclic group increases the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in raising.

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

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

［式中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、炭素数１〜５のアルコキシ基または−ＣＯＯＲ”であり、前記Ｒ”は水素原子、または炭素数１〜１５の直鎖状、分岐鎖状もしくは環状のアルキルキル基であり、ｍは０または１の整数であり、Ａ”は酸素原子もしくは硫黄原子を含んでいてもよい炭素数１〜５のアルキレン基、酸素原子または硫黄原子である。］

[Wherein, R is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, an alkoxy group having 1 to 5 carbon atoms, or —COOR ″, wherein R ″ is A hydrogen atom or a linear, branched or cyclic alkylalkyl group having 1 to 15 carbon atoms, m is an integer of 0 or 1, and A ″ is a carbon which may contain an oxygen atom or a sulfur atom. It is an alkylene group of formula 1 to 5, an oxygen atom or a sulfur atom.]

R in the general formulas (a2-1) to (a2-5) is the same as R in the structural unit (a1).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
When R ″ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ″ is a cyclic alkyl group, it preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, a fluorine atom or fluorine atom A group obtained by removing one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, etc., which may or may not be substituted with an alkyl group. Specific examples thereof include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Can be mentioned.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Specific examples of the alkylene group having 1 to 5 carbon atoms that may contain an oxygen atom or sulfur atom of A ″ include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, —O—CH ₂ —. _{, -CH 2 -O-CH 2 -} , - S-CH 2 -, - CH 2 -S-CH 2 - , and the like.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

In the component (A), as the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
As the structural unit (a2), at least one selected from the group consisting of structural units represented by the general formulas (a2-1) to (a2-5) is preferable, and the general formulas (a2-1) to (a2) -3) At least 1 sort (s) selected from the group which consists of a structural unit represented by 3) is more preferable. Among them, chemical formulas (a2-1-1), (a2-1-2), (a2-1-3), (a2-1-4), (a2-2-1), (a2-2-2) ), (A2-2-9), (a2-2-10), (a2-3-1), (a2-3-2), (a2-3-9) and (a2-3-10) It is preferable to use at least one selected from the group consisting of the structural units represented.

  When the component (A) includes the structural unit (a2), the proportion of the structural unit (a2) in the component (A) is 1 mol% with respect to the total of all the structural units constituting the component (A). The content is preferably less than 20 mol%, more preferably 1 to 15 mol%, and still more preferably 5 to 15 mol%. The effect by containing the structural unit (a2) is sufficiently obtained by setting it to the lower limit value or more, and by setting it to the upper limit value or less, the solubility of the component (A) in the organic solvent (S) described later is sufficient. In addition to being able to balance with other structural units.

・ Structural unit (a3)
The component (A) is within the range not impairing the effects of the present invention, in addition to the structural unit (a0-1), the structural unit (a0-2) and the structural unit (a1), and the general formula (a0-1) or The structural unit represented by (a0-2) may have a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group that is not included.
When the component (A) has the structural unit (a3), the hydrophilicity of the component (A) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. Contributes to improvement.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). It is done. As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

  As the structural unit (a3), when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a polycyclic group, the structural unit represented by the following formula (a3-1), represented by (a3-2) The structural unit is preferably mentioned.

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

[Wherein, R is the same as defined above, k is an integer of 1 to 3, t ′ is an integer of 1 to 3, l is an integer of 1 to 5, and s is an integer of 1 to 3] It is. ]

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

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

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
When the component (A) includes the structural unit (a3), the proportion of the structural unit (a3) in the component (A) is 1 to 30 mol% with respect to all the structural units constituting the component (A). It is preferably 5 to 30 mol%, more preferably 10 to 20 mol%.

・ Structural unit (a4)
The component (A) includes other structural unit (a4) in addition to the structural unit (a0-1), the structural unit (a0-2) and the structural unit (a1) as long as the effects of the present invention are not impaired. You may go out.
The structural unit (a4) is not particularly limited as long as it is another structural unit not classified into the above structural units (a0-1), (a0-2) and (a1) to (a3). ArF excimer Many things conventionally known can be used as what is used for resist resins, such as a laser and a KrF excimer laser (preferably ArF excimer laser).

As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

［式中、Ｒは前記と同じである。］

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

  When the structural unit (a4) is contained in the component (A), the structural unit (a4) is preferably contained in an amount of 1 to 30 mol% based on the total of all the structural units constituting the component (A). 10 to 20 mol% is more preferable.

  In the present invention, the component (A) includes the structural unit (a0-1) represented by the general formula (a0-1) and the structural unit (a0-2) represented by the general formula (a0-2). It is preferable that it is a copolymer (A2) which has. Examples of the copolymer (A2) include terpolymers composed of the structural units (a0-1), (a0-2), and (a1).

In the present invention, as the copolymer (A2), in particular, a copolymer (A-21) containing three structural units of the combination shown in the following general formula (A-21), the following general formula (A- 22) A copolymer (A-22) containing three structural units in combination and a copolymer (A-23) containing three structural units in combination shown in the following general formula (A-23) It is preferable to contain any one or more of them. Especially, it is preferable to contain a copolymer (A-21). In the component (A), as the copolymer (A2), one type may be used alone, or two or more types may be used in combination.

［式（Ａ−２１）中、Ｒ，Ｒ^２１〜Ｒ^２３，ｅは上記と同様であり、複数のＲは相互に同じであっても異なっていてもよく、Ｒ^２７は低級アルキル基である。式（Ａ−２２）中、Ｒ，Ｒ^２１〜Ｒ^２３，ｅは上記と同様であり、複数のＲは相互に同じであっても異なっていてもよく、Ｒ^２８は低級アルキル基である。］

[In the formula (A-21), R, R ^{21 to} R ²³ and e are the same as described above, and a plurality of R may be the same or different from each other, and R ²⁷ is a lower alkyl group. . In formula (A-22), R, R ^{21 to} R ²³ and e are the same as described above, and a plurality of Rs may be the same or different from each other, and R ²⁸ is a lower alkyl group. ]

［式（Ａ−２３）中、Ｒ，Ｒ^２１〜Ｒ^２３，ｅは上記と同様であり、複数のＲは相互に同じであっても異なっていてもよく、ｎは上記式（ｐ１）中のｎと同様である。式（Ａ−２４）中、Ｒ，Ｒ^２１〜Ｒ^２３，Ｒ^２８，ｅは上記と同様であり、複数のＲは相互に同じであっても異なっていてもよい。］

[In the formula (A-23), R, R ^{21 to} R ²³ , e are the same as described above, and a plurality of R may be the same or different from each other, and n is in the formula (p1). This is the same as n in FIG. In formula (A-24), R, R ^{21 to} R ²³ , R ²⁸ , and e are the same as described above, and a plurality of R may be the same as or different from each other. ]

  The component (A) may contain at least one copolymer having both the structural unit (a0-1) and the structural unit (a0-2) as described above, and at least It may be a mixture of a polymer having the structural unit (a0-1) and a polymer having at least the structural unit (a0-2).

The component (A) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
In addition, the component (A) is used in combination with a chain transfer agent such as, for example, HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH at the time of the polymerization. A —C (CF ₃ ) ₂ —OH group may be introduced into the. Thus, a copolymer into which a hydroxyalkyl group in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms is effective in reducing LWR. Further, it is effective for reducing development defects and LER (line edge roughness: uneven unevenness of line side walls).

The weight average molecular weight (Mw) of the component (A) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and most preferably 5000 to 20000. preferable.
When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape are larger than the lower limit of this range.
The dispersity (Mw / number average molecular weight (Mn)) is not particularly limited, but is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and 1.2 to 2. 5 is most preferred.
In addition, Mn shows a number average molecular weight.

<(B) component>
(B) It does not specifically limit as a component, What has been proposed as an acid generator for chemical amplification type resists until now can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

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

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

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

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. In addition, any two of R ¹ ″ to R ³ ″ in formula (b-1) may be bonded to each other to form a ring together with the sulfur atom in the formula.
Further, at least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl or alkoxy A group, a halogen atom, a hydroxyl group, an alkoxyalkyloxy group, an alkoxycarbonylalkyloxy group, or the like may or may not be substituted. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
As the alkoxy group that may be substituted for the hydrogen atom of the aryl group, an alkoxy group having 1 to 5 carbon atoms is preferable, and a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, Most preferred is a tert-butoxy group.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may substitute the hydrogen atom of the aryl group is preferably a fluorine atom.

Examples of the alkoxyalkyloxy group in which the hydrogen atom of the aryl group may be substituted include, for example, a general formula: —O—C (R ⁴⁷ ) (R ⁴⁸ ) —O—R ⁴⁹ [wherein R ⁴⁷ , R ⁴⁸ are each independently a hydrogen atom or a linear or branched alkyl group, and R ⁴⁹ is an alkyl group.
In R ⁴⁷ and R ⁴⁸ , the alkyl group preferably has 1 to 5 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group.
At least one of R ⁴⁷ and R ⁴⁸ is preferably a hydrogen atom. In particular, it is more preferable that one is a hydrogen atom and the other is a hydrogen atom or a methyl group.
The alkyl group for R ⁴⁹ preferably has 1 to 15 carbon atoms and may be linear, branched or cyclic.
The linear or branched alkyl group for R ⁴⁹ preferably has 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, and a tert-butyl group. Can be mentioned.
The cyclic alkyl group for R ⁴⁹ preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, a monocycloalkane, bicycloalkane, tricycloalkane, tetracycloalkane, etc., which may or may not be substituted with an alkyl group having 1 to 5 carbon atoms, a fluorine atom or a fluorinated alkyl group, etc. And a group obtained by removing one or more hydrogen atoms from the polycycloalkane. Examples of the monocycloalkane include cyclopentane and cyclohexane. Examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.

Examples of the alkoxycarbonylalkyloxy group in which the hydrogen atom of the aryl group may be substituted include, for example, a general formula: —O—R ⁵⁰ —C (═O) —O—R ^{51 wherein} R ⁵⁰ is A chain or branched alkylene group, and R ⁵¹ is a tertiary alkyl group. ] Is represented.
The linear or branched alkylene group for R ⁵⁰ preferably has 1 to 5 carbon atoms, such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, or a 1,1-dimethylethylene group. Etc.
As the tertiary alkyl group for R ⁵¹ , 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 1-methyl-1-cyclopentyl group, 1-ethyl-1-cyclopentyl group, 1-methyl -1-cyclohexyl group, 1-ethyl-1-cyclohexyl group, 1- (1-adamantyl) -1-methylethyl group, 1- (1-adamantyl) -1-methylpropyl group, 1- (1-adamantyl) -1-methylbutyl group, 1- (1-adamantyl) -1-methylpentyl group; 1- (1-cyclopentyl) -1-methylethyl group, 1- (1-cyclopentyl) -1-methylpropyl group, 1- (1-cyclopentyl) -1-methylbutyl group, 1- (1-cyclopentyl) -1-methylpentyl group; 1- (1-cyclohexyl) -1-methylethyl Group, 1- (1-cyclohexyl) -1-methylpropyl group, 1- (1-cyclohexyl) -1-methylbutyl group, 1- (1-cyclohexyl) -1-methylpentyl group, tert-butyl group, tert -Pentyl group, tert-hexyl group and the like.

The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, linear C1-10, branched or cyclic alkyl group, and the like. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are most preferably a phenyl group or a naphthyl group, respectively.

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

R ⁴ ″ represents a linear, branched or cyclic alkyl group or fluorinated alkyl group which may have a substituent. As the substituent which R ⁴ ″ may have, halogen An atom, a hetero atom, an alkyl group, etc. are mentioned.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. A fluorinated alkyl group (perfluoroalkyl group) is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

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

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

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

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

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

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Most preferably, it has 3 carbon atoms.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, 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 onium salt type acid generator which replaced the anion part by the anion part represented by the following general formula (b1-12) in the said general formula (b-1) or (b-2) can also be used ( The cation moiety is the same as (b-1) or (b-2).
R ² —O—Y ¹ ′ —SO ₃ ^— (b1-12)
[Wherein R ² is a monovalent aromatic organic group; Y ¹ ′ is an optionally substituted alkylene group having 1 to 4 carbon atoms. ]

In the general formula (b1-12), R ² is a monovalent aromatic organic group; Y ¹ ′ is an optionally substituted alkylene group having 1 to 4 carbon atoms.
Examples of the monovalent aromatic organic group of R ² include hydrogen from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. An aryl group with one atom removed; a heteroaryl group in which some of the carbon atoms constituting the ring of these aryl groups are substituted with a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom; a benzyl group or a phenethyl group And arylalkyl groups. The alkyl chain in the arylalkyl group preferably has 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably 1 to 2 carbon atoms. These aryl group, heteroaryl group, and arylalkyl group may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom. The alkyl group or halogenated alkyl group in the substituent preferably has 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. The halogenated alkyl group is preferably a fluorinated alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom, and a fluorine atom is preferable.
The number of carbon atoms of the monovalent aromatic organic group R ² is 6-20, more preferably 6-10, particularly preferably 10.
The monovalent aromatic organic group for R ² is more preferably an arylalkyl group such as a benzyl group or a phenethyl group, and particularly preferably a benzyl group.

As the optionally substituted fluorine-substituted alkylene group for Y ¹ ′,
_{-CF 2 -, - CF 2 CF} 2 -, - CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 -, - CF (CF 2 CF 3) -, - C (CF 3) 2 -, _{-CF 2 CF 2 CF 2 CF 2} -, - CF (CF 3) CF 2 CF 2 -, - CF 2 CF (CF 3) CF 2 -, - CF (CF 3) CF (CF 3) -, - C _{(CF 3) 2 CF 2 -} , - CF (CF 2 CF 3) CF 2 -, - CF (CF 2 CF 2 CF 3) -, - C (CF 3) (CF 2 CF 3) -;
_{-CHF -, - CH 2 CF 2} -, - CH 2 CH 2 CF 2 -, - CH 2 CF 2 CF 2 -, - CH (CF 3) CH 2 -, - CH (CF 2 CF 3) -, - _{C (CH 3) (CF 3} ) -, - CH 2 CH 2 CH 2 CF 2 -, - CH 2 CH 2 CF 2 CF 2 -, - CH (CF 3) CH 2 CH 2 -, - CH 2 CH ( _{CF 3) CH 2 -, -} CH (CF 3) CH (CF 3) -, - C (CF 3) 2 CH 2 -;
_{-CH 2 -, - CH 2 CH} 2 -, - CH 2 CH 2 CH 2 -, - CH (CH 3) CH 2 -, - CH (CH 2 CH 3) -, - C (CH 3) 2 -, _{-CH 2 CH 2 CH 2 CH 2} -, - CH (CH 3) CH 2 CH 2 -, - CH 2 CH (CH 3) CH 2 -, - CH (CH 3) CH (CH 3) -, - C (CH ₃ ) ₂ CH ₂ —, —CH (CH ₂ CH ₃ ) CH ₂ —, —CH (CH ₂ CH ₂ CH ₃ ) —, —C (CH ₃ ) (CH ₂ CH ₃ ) —; be able to.

Further, the Y 1 ^', the fluorine substituents on these alkylene group having 1 to 4 carbon atoms, it is preferred that the carbon atom bonded to S is fluorinated, as such a fluorinated alkylene group,
_{-CF 2 -, - CF 2 CF} 2 -, - CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 -, - CF 2 CF 2 CF 2 CF 2 -, - CF (CF 3) CF 2 _{CF 2 -, - CF 2 CF} (CF 3) CF 2 -, - CF (CF 3) CF (CF 3) -, - C (CF 3) 2 CF 2 -, - CF (CF 2 CF 3) CF 2 -;
_{-CH 2 CF 2 -, - CH} 2 CH 2 CF 2 -, - CH 2 CF 2 CF 2 -;
_{-CH 2 CH 2 CH 2 CF 2} -, - CH 2 CH 2 CF 2 CF 2 -, - CH 2 CF 2 CF 2 CF 2 -; and the like.
Of _these, -CF ₂ CF 2 -, _- CF 2 _CF 2 CF ₂ -, or _CH 2 _CF 2 CF ₂ - is preferable, _-CF 2 CF ₂ - or _CF 2 _CF 2 CF ₂ - is more preferable, - CF ₂ CF ₂ — is particularly preferred.

  Specific examples of the onium salt acid generator replaced with the anion moiety represented by the general formula (b1-12) are represented by the following formulas (b-12-1) to (b-12-18). Compounds.

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

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

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

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

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

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

［式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。］

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

The organic groups of R ³¹ and R ³² are groups containing carbon atoms, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms (fluorine atoms, chlorine atoms, etc.), etc.) You may have.
As the organic group for R ^31, a linear, branched, or cyclic alkyl group or aryl group is preferable. These alkyl groups and aryl groups may have a substituent. There is no restriction | limiting in particular as this substituent, For example, a fluorine atom, a C1-C6 linear, branched or cyclic alkyl group etc. are mentioned. Here, “having a substituent” means that part or all of the hydrogen atoms of the alkyl group or aryl group are substituted with a substituent.
As an alkyl group, C1-C20 is preferable, C1-C10 is more preferable, C1-C8 is more preferable, C1-C6 is especially preferable, and C1-C4 is the most preferable. As the alkyl group, a partially or completely halogenated alkyl group (hereinafter sometimes referred to as a halogenated alkyl group) is particularly preferable. The partially halogenated alkyl group means an alkyl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated alkyl group means that all of the hydrogen atoms are halogen atoms. Means an alkyl group substituted with Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.
The aryl group preferably has 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms. As the aryl group, a partially or completely halogenated aryl group is particularly preferable. The partially halogenated aryl group means an aryl group in which a part of hydrogen atoms is substituted with a halogen atom, and the fully halogenated aryl group means that all of the hydrogen atoms are halogen atoms. Means an aryl group substituted with.
R ³¹ is particularly preferably an alkyl group having 1 to 4 carbon atoms 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 preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Also, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO 2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

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

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, it is preferable to use, as the component (B), an onium salt having a fluorinated alkyl sulfonate ion as an anion.
Content of (B) component in the positive resist composition of this invention is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. 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.

<(S) component>
The positive resist composition of the present invention is obtained by dissolving the component (A) and the component (B) in an organic solvent (S) (hereinafter sometimes referred to as the component (S)).
In the positive resist composition of the present invention, the component (S) is an organic solvent that does not dissolve the first resist film described later and can dissolve the components (A) and (B). By containing the component (S), the positive resist composition of the present invention is applied onto a support on which a first resist pattern formed by the first positive resist composition described later is formed. However, the first resist pattern is hardly dissolved, and the resist pattern can be stably formed by the double patterning method.

  The (S) component is an organic solvent that has almost no compatibility with the first resist film described later, and can dissolve the (A) component and the (B) component to form a uniform solution. As long as the solvent is not particularly limited, any one or more of conventionally known solvents for chemically amplified resists can be appropriately selected and used.

-(S1) Component In the positive resist composition of the present invention, the (S) component is particularly preferably an alcoholic organic solvent (hereinafter sometimes referred to as the (S1) component).
Here, the “alcohol-based organic solvent” is a compound in which at least one of the hydrogen atoms of the aliphatic hydrocarbon is substituted with a hydroxyl group, and is a compound that is liquid at normal temperature and normal pressure.

As the component (S1), a monohydric alcohol is preferable. Among them, although depending on the number of carbon atoms, a primary or secondary monohydric alcohol is more preferable, and a primary monohydric alcohol is most preferable.
The boiling point of the alcohol-based organic solvent is preferably 80 to 160 ° C., more preferably 90 to 150 ° C., and preferably 100 to 135 ° C., coating properties, stability of composition during storage, and PAB process. And the most preferable from the viewpoint of the heating temperature in the PEB process.
Here, the monohydric alcohol means a case where the number of hydroxy groups contained in the alcohol molecule is 1, and does not include a dihydric alcohol, a trihydric alcohol, or a derivative thereof.

  Examples of alcohol-based organic solvents include n-pentyl alcohol (boiling point 138.0 ° C), s-pentyl alcohol (boiling point 119.3 ° C), t-pentyl alcohol (101.8 ° C), isopentyl alcohol (boiling point 130.8). ° C), isobutanol (also called isobutyl alcohol or 2-methyl-1-propanol) (boiling point 107.9 ° C), isopropyl alcohol (boiling point 82.3 ° C), 2-ethylbutanol (boiling point 147 ° C), neopentyl alcohol (Boiling point 114 ° C), n-butanol (boiling point 117.7 ° C), s-butanol (boiling point 99.5 ° C), t-butanol (boiling point 82.5 ° C), 1-propanol (boiling point 97.2 ° C), n-hexanol (boiling point 157.1 ° C.), 2-heptanol (boiling point 160.4 ° C.), 3-heptanol (boiling point 15 2 ° C.), 2-methyl-1-butanol (boiling point 128.0 ° C.), 2-methyl-2-butanol (boiling point 112.0 ° C.), 4-methyl-2-pentanol (boiling point 131.8 ° C.) Etc. In particular, isobutanol (2-methyl-1-propanol), 4-methyl-2-pentanol, n-butanol, and the like are preferable because the effect of containing the component (S1 ′) is good. Among these, isobutanol and n-butanol are preferable, and isobutanol is most preferable.

These (S1) components may be used individually by 1 type, and may use 2 or more types.
In the present invention, the component (S1) particularly preferably contains isobutanol.
The content of the component (S1) is preferably 50% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass in the component (S). By being more than the lower limit of this range, when the positive resist composition of the present invention is applied, the first resist pattern is more difficult to dissolve.

-(S2) component In the range which does not impair the effect of this invention, in addition to (S1) component, (S1) component is an ether type organic solvent which does not have a hydroxyl group (henceforth (S2) component). May be included.
Here, the “ether-based organic solvent having no hydroxyl group” is a compound that has an ether bond (C—O—C) in its structure, has no hydroxyl group, and is liquid under normal temperature and normal pressure. is there.
The ether-based organic solvent having no hydroxyl group preferably further has no carbonyl group in addition to the hydroxyl group.
Preferred examples of the ether organic solvent having no hydroxyl group include compounds represented by the following general formula (s1′-1).
R ⁴⁰ —O—R ⁴¹ (s1′-1)
[Wherein, R ⁴⁰ and R ⁴¹ each independently represent a hydrocarbon group. Alternatively, R ⁴⁰ and R ⁴¹ may be bonded to form a ring. -O- represents an ether bond. ]

In the above formula, examples of the hydrocarbon group for R ⁴⁰ and R ⁴¹ include an alkyl group and an aryl group, and an alkyl group is preferred. Among ^them, it is preferable that any of R ^{40, R 41} is an alkyl ^group, more preferably a ^{R 40} and ^{R 41} are the same alkyl group.
As each of the alkyl groups of R ^40, R ^41, not particularly limited, for example, straight, branched or cyclic alkyl group, and the like. In the alkyl group, part or all of the hydrogen atoms may or may not be substituted with a halogen atom or the like.
The alkyl group preferably has 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, because the coating properties of the resist composition are good. Specific examples include an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, an isopentyl group, a cyclopentyl group, and a hexyl group, and an n-butyl group and an isopentyl group are particularly preferable. .
The halogen atom that may be substituted for the hydrogen atom of the alkyl group is preferably a fluorine atom.

Each aryl group for R ⁴⁰ and R ⁴¹ is not particularly limited, and is, for example, an aryl group having 6 to 12 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 halogen atom or the like.
The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specifically, a phenyl group, a benzyl group, a naphthyl group, etc. are mentioned, for example.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is more preferable.
As the alkoxy group which may substitute the hydrogen atom of the aryl group, a C1-C5 alkoxy group is preferable, and a methoxy group and an ethoxy group are more preferable.
The halogen atom that may substitute the hydrogen atom of the aryl group is preferably a fluorine atom.

In the above formula, R ⁴⁰ and R ⁴¹ may combine to form a ring.
R ⁴⁰ and R ⁴¹ are each independently a linear or branched alkylene group (preferably an alkylene group having 1 to 10 carbon atoms), and the end of R ^{40 and} the end of R ⁴¹ are bonded to each other. To form a ring. In addition, the carbon atom of the alkylene group may be substituted with an oxygen atom.
Specific examples of such ether-based organic solvents include 1,8-cineol, tetrahydrofuran, dioxane and the like.

  The boiling point (under normal pressure) of the ether-based organic solvent having no hydroxyl group is preferably 30 to 300 ° C, more preferably 100 to 200 ° C, and further preferably 140 to 180 ° C. By being above the lower limit of the temperature range, during spin coating during application of the positive resist composition of the present invention, the (S) component is less likely to evaporate, and coating unevenness is suppressed and coating properties are improved. On the other hand, by being below the upper limit, the (S) component is sufficiently removed from the resist film by pre-baking, and the formability of the second resist film is improved. Moreover, when the temperature is within this range, the effect of reducing the film thickness of the resist pattern and the stability of the composition during storage are further improved. Moreover, it is preferable also from a viewpoint of the heating temperature of a PAB process or a PEB process.

  Specific examples of ether organic solvents having no hydroxyl group include, for example, 1,8-cineol (boiling point 176 ° C.), dibutyl ether (boiling point 142 ° C.), diisopentyl ether (boiling point 171 ° C.), dioxane (boiling point 101 ° C.). ), Anisole (boiling point 155 ° C.), ethyl benzyl ether (boiling point 189 ° C.), diphenyl ether (boiling point 259 ° C.), dibenzyl ether (boiling point 297 ° C.), phenetole (boiling point 170 ° C.), butyl phenyl ether, tetrahydrofuran (boiling point 66 ° C.) ), Ethyl propyl ether (boiling point 63 ° C.), diisopropyl ether (boiling point 69 ° C.), dihexyl ether (boiling point 226 ° C.), dipropyl ether (boiling point 91 ° C.) and the like.

These (S2) components may be used individually by 1 type, and may use 2 or more types.
In the present invention, the component (S2) is preferably a cyclic or chain ether-based organic solvent because of its good effect of reducing the film loss of the resist pattern, and among them, 1,8-cineol, dibutyl ether and At least one selected from the group consisting of diisopentyl ether is preferred.

-(S3) component In the range which does not impair the effect of this invention, in addition to (S1) component, (S1) component is organic solvent other than (S1) component and (S2) component (henceforth (S3) component). .) Can be used in combination. By using the component (S3) in combination, the solubility and other characteristics of the component (A) and the component (B) can be adjusted.
As the component (S3), for example, one or two or more kinds of conventionally known solvents as chemical amplification resists can be appropriately selected and used.

Examples of the component (S3) include lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether [in these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME) Is preferred];
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate;
Aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene, etc. be able to.
These (S3) components may be used individually by 1 type, and may use 2 or more types.

  The amount of the component (S) used as a whole is not particularly limited, but an amount that makes the positive resist composition of the present invention a liquid having a concentration that can be applied onto a support is used.

<Optional component>
[Component (D)]
In the positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Can be blended.
Since a wide variety of components (D) have already been proposed, any known one may be used. Cyclic amines, aliphatic amines, particularly secondary aliphatic amines and tertiary fats may be used. Group amines are preferred. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms. Specific examples thereof include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n-heptylamine, Dialkylamines such as di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptyl Trialkylamines such as amine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n -Ok Noruamin, alkyl alcohol amines such as tri -n- octanol amine.
Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are most preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

[(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 phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.

(E) A component may be used individually by 1 type and may use 2 or more types together.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  In the double patterning method using the positive resist composition as the first resist composition, when the positive resist composition of the present invention is used as the second resist composition, the first resist composition formed on the support is used. Even if the positive resist composition of the present invention is directly applied on the resist pattern, the second resist pattern can be formed without impairing the first resist pattern. The reason why such an effect is obtained is not clear, but the following can be considered. That is, by having the structural units (a0-1) and (a0-2) as the component (A), it is also possible for an organic solvent such as an alcohol-based organic solvent in which a conventional positive resist composition is difficult to dissolve. Since it can be sufficiently dissolved, an organic solvent that does not dissolve the conventional positive resist composition can be used as the component (S). That is, since the positive resist composition of the present invention is an organic solvent that does not dissolve the first resist film (S), which will be described later, the first resist pattern is difficult to dissolve, and the resist pattern is formed by a double patterning method. It can be formed stably.

The reason why the positive resist composition of the present invention has high solubility in an organic solvent in which a conventional positive resist composition is difficult to dissolve, such as an alcohol-based organic solvent, is not clear, but the following may be considered. . Many of positive resist compositions conventionally used for ArF excimer laser lithography and the like are polar group-containing aliphatics for the purpose of improving affinity with a developer and improving alkali solubility in an exposed area. It contains many structural units having a hydrocarbon group, for example, a structure such as “—Y ¹ (aliphatic cyclic group) —OH”. On the other hand, the positive resist composition of the present invention contains a structural unit (a0-1) having a structure of “—Y ¹ — (CH ₂ ) e—O—Z” as the component (A). Since Z in this “—Y ¹ — (CH ₂ ) e—O—Z” is less polar than a hydrogen atom and has a somewhat long molecular chain length, it can be used as an alcohol-based organic solvent as component (A). It is presumed that the affinity is increased and the solubility is improved. In addition, the positive resist composition of the present invention has an alcohol-based organic compound as a component (A) by having the structural unit (a0-2) in addition to the structural unit (a0-1) without impairing the lithography properties. It is presumed that the solubility in a solvent or the like can be improved.

≪Resist pattern formation method≫
In the resist pattern forming method of the present invention, a positive resist composition (hereinafter also referred to as a first positive resist composition) is applied on a support to form a first resist film ( Hereinafter, a film forming step (1)) and a step of selectively exposing the first resist film and performing alkali development to form a first resist pattern (hereinafter referred to as a patterning step (1)). And a step of forming a second resist film by applying the positive resist composition of the present invention on the support on which the first resist pattern is formed (hereinafter referred to as film forming step (2)). And a step of selectively exposing the second resist film and performing alkali development to form a resist pattern (hereinafter referred to as a patterning step (2)).
Hereinafter, each step will be described in more detail.

[Film Formation Step (1)]
The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
Further, the support may be a substrate in which an inorganic and / or organic film is provided on the above-described substrate. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include an organic antireflection film (organic BARC).

The first resist film can be formed by a conventionally known method, for example, by applying a positive resist composition on a support. The positive resist composition can be applied by a conventionally known method using a spinner or the like.
The positive resist composition used for forming the first resist film (hereinafter sometimes referred to as the first positive resist composition) will be described in detail later.
Specifically, for example, the first positive resist composition is applied onto a support with a spinner or the like, and is baked (pre-baked) at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60. The first resist film can be formed by applying for ~ 90 seconds and volatilizing the organic solvent.
The thickness of the resist film is preferably 50 to 500 nm, more preferably 50 to 450 nm. By setting it within this range, there are effects such that a resist pattern can be formed with high resolution and sufficient resistance to etching can be obtained.

[Patterning process (1)]
The patterning step (1) can be performed using a conventionally known method. For example, the first resist film is selectively exposed through a mask (mask pattern) on which a predetermined pattern is formed. Baking treatment (PEB (post-exposure heating)) is applied for 40 to 120 seconds, preferably 60 to 90 seconds under a temperature condition of ˜150 ° C., for example, tetramethylammonium hydroxide having a concentration of 0.1 to 10% by mass ( When alkali development is performed with an aqueous solution of TMAH), the exposed portion of the first resist film is removed and a first resist pattern is formed.
In some cases, a post-baking step may be included after the alkali development.
The wavelength used for exposure is not particularly limited, and includes KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation.

At this time, the selective exposure of the first resist film may be normal exposure (dry exposure) performed in an inert gas such as air or nitrogen, or may be performed by immersion exposure.
In immersion exposure, as described above, the portion between the lens, which has been filled with an inert gas such as air or nitrogen, and the resist film on the wafer at the time of exposure is refracted larger than the refractive index of air. The exposure is performed in a state filled with a solvent having a high rate (immersion medium).
More specifically, the immersion exposure is a solvent (immersion medium) having a refractive index larger than the refractive index of air between the resist film obtained as described above and the lowermost lens of the exposure apparatus. And in this state, exposure (immersion exposure) is performed through a desired mask pattern.
As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film (first resist film in the patterning step (1)) exposed by the immersion exposure. Is preferred. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, a silicon-based solvent, and a hydrocarbon-based solvent.
Specific examples of the fluorinated inert liquid include fluorinated compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as main components. Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).

[Film Formation Step (2)]
Next, the positive resist composition of the present invention is applied on the support on which the first resist pattern is formed, thereby forming a second resist film that fills the gaps between the plurality of resist patterns.
Similar to the first resist film, the second resist film can be formed by a conventionally known method.
The film thickness of the second resist film is preferably at least the same as or higher than the height of the first resist pattern. That is, when the support is viewed from the second resist film side, the surface is preferably flat.

[Patterning process (2)]
Next, a position different from the position where the plurality of resist patterns are formed on the second resist film is selectively exposed and developed. Thereby, the unexposed portion of the second resist film is removed, and a plurality of resist patterns are newly formed between the plurality of resist patterns. As a result, a resist pattern including a plurality of resist patterns and a plurality of resist patterns newly formed on the second resist film is formed on the support.
Here, in the present invention, except for the case where it completely coincides with the first resist pattern, all are “positions different from the position where the first resist pattern is formed”, and there are no overlaps and some Including duplicate cases.
In the present invention, it is preferable that the position where the first resist pattern is formed and the position where the first resist pattern is selectively exposed do not overlap at all. Thereby, a narrow pitch pattern in which the interval (pitch) between patterns is narrower than the first resist pattern formed in the patterning step (1) can be formed.

The selective exposure at a position different from the position where the first resist pattern is formed can be performed by, for example, a method using a mask pattern different from the first mask pattern used in the patterning step (1).
For example, in the case of forming a line-and-space resist pattern, for example, in the patterning step (1), a line-and-space sparse pattern using a line-and-space mask pattern in which a plurality of lines are arranged at a constant pitch. In the patterning step (2), the mask pattern is changed, and a line pattern is formed at an intermediate position between the line pattern and the line pattern formed in the patterning step (1). A line-and-space resist pattern is formed at a pitch about half the line-and-space pitch. That is, a dense resist pattern having a narrower pitch than the initially formed sparse pattern is formed.
Here, the “sparse pattern” means a line and space pattern in which a line width: space width = 1: 2 or more is wide in a line and space resist pattern.
As described above, in the present invention, the first resist pattern is preferably a line and space resist pattern. Thereby, a narrow line and space pattern with a narrow pitch can be formed.
Specifically, for example, after forming a line and space pattern (sparse pattern) having a line width of 100 nm and a line width: space width = 1: 3, the mask pattern is translated by 200 nm in a direction perpendicular to the line direction. By forming a line and space pattern having a line width of 100 nm and line width: space width = 1: 3, a line and space pattern (dense pattern) having a line width of 100 nm and line width: space width = 1: 1 is obtained. Can be formed.
Further, the mask pattern used in the patterning step (1) is rotated and moved or a mask pattern different from the mask pattern used in the patterning step (1) (for example, a line-and-space mask pattern or patterning in the patterning step (1)). By using a hole mask pattern or the like in step (2), etc., fine and / or various resist patterns can be formed.

<First positive resist composition>
In the film forming step (1) described above, the first positive resist composition for forming the first resist film is particularly limited as long as it is a positive resist composition having low compatibility with the organic solvent (S) component. However, it is preferably a chemically amplified positive resist composition. The chemical amplification type positive resist composition is not particularly limited, and is appropriately selected according to the exposure light source to be used, lithography characteristics, etc., from among many positive resist compositions conventionally proposed for ArF resists and the like. It can be selected and used.
The chemically amplified positive resist composition includes a resin component (A ′) (hereinafter referred to as (A ′) component) whose solubility in an alkaline developer is increased by the action of an acid, and an acid that generates an acid upon exposure. A material containing a generator component (B ′) (hereinafter referred to as “component (B ′)”) is generally used.

[(A ′) component]
・ Structural unit (a1)
In the first positive resist composition, the component (A ′) preferably contains a copolymer (A1) containing the structural unit (a1). Here, the structural unit (a1) is a structural unit derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, and is listed in the positive resist composition according to the first aspect of the present invention. It is the same.
As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Moreover, as a structural unit (a1), arbitrary things can be used, without being specifically limited. In particular, the structural unit represented by the general formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) and (a1-1-35) to (a1- It is more preferable to use at least one selected from the group 1-41).
In the copolymer (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, based on all the structural units constituting the copolymer (A1). More preferred is ˜50 mol%. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
The copolymer (A1) preferably has a structural unit (a2) in addition to the structural unit (a1). Here, the structural unit (a1) is a structural unit derived from an acrylate ester containing a lactone-containing cyclic group, and is listed in the positive resist composition according to the first aspect of the present invention. It is the same.
As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
Further, the structural unit (a2) is not particularly limited, and any unit can be used. In particular, at least one selected from the group consisting of the structural units represented by the general formulas (a2-1) to (a2-5) is preferable, and represented by the general formulas (a2-1) to (a2-3). More preferably, at least one selected from the group consisting of structural units is represented by the chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2) , (A2-2-9), (a2-2-10), (a2-3-1), (a2-3-2), (a2-3-9) and (a2-3-10) It is more preferable to use at least one selected from the group consisting of structural units.
5-60 mol% is preferable with respect to the sum total of all the structural units which comprise a copolymer (A1), and the ratio of the structural unit (a2) in a copolymer (A1) is 10-50 mol% more. Preferably, 20-50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3 ′)
The copolymer (A1) preferably has a structural unit (a3 ′) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1).
When the component (A1) has the structural unit (a3 ′), the hydrophilicity of the component (A ′) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. Contributes to the improvement of sex.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). It is done. As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like. Specific examples include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

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

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

[Wherein, R is as defined above, j is an integer of 1 to 3, k is an integer of 1 to 3, t ′ is an integer of 1 to 3, and l is an integer of 1 to 5] And s is an integer of 1 to 3. ]

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

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

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

As the structural unit (a3 ′), one type may be used alone, or two or more types may be used in combination.
In the copolymer (A1), the proportion of the structural unit (a3 ′) is preferably from 5 to 50 mol%, more preferably from 5 to 40 mol%, based on all the structural units constituting the copolymer. 5 to 25 mol% is more preferable.

・ Structural unit (a4 ′)
The copolymer (A1) may contain other structural units (a4 ′) other than the structural units (a1), (a2), and (a3 ′) as long as the effects of the present invention are not impaired.
The structural unit (a4 ′) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1), (a2), and (a3 ′) described above. For ArF excimer laser, KrF excimer laser For example, a positive resist composition according to the first aspect of the present invention can be used. For example, a positive resist composition according to the first aspect of the present invention can be used as a resist resin for use in resist (preferably for ArF excimer laser). Can be used.

  When the structural unit (a4 ′) is contained in the copolymer (A1), the structural unit (a4 ′) is added in an amount of 1 to 30 mol with respect to the total of all the structural units constituting the copolymer (A1). %, Preferably 10 to 20 mol%.

In the first positive resist composition, the copolymer (A1) is preferably a copolymer having a structural unit (a1). Examples of such a copolymer include the structural unit (a1), ( Examples thereof include a copolymer comprising a2) and (a3).
In the component (A ′), as the copolymer (A1), one type may be used alone, or two or more types may be used in combination.
In the first positive resist composition, the copolymer (A1) preferably contains a combination of structural units such as the following general formula (A-11).

The component (A ′) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). .
In addition, for the component (A ′), in the polymerization, a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination, -C terminated _{(CF 3)} may be introduced 2 -OH group. Thus, a copolymer into which a hydroxyalkyl group in which some of the hydrogen atoms of the alkyl group are substituted with fluorine atoms is effective in reducing LWR. Further, it is effective for reducing development defects and LER (line edge roughness: uneven unevenness of line side walls).

The mass average molecular weight (Mw) of the component (A ′) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 20000. Most preferred.
When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape are larger than the lower limit of this range.
The dispersity (Mw / number average molecular weight (Mn)) is not particularly limited, but is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and 1.2 to 2. 5 is most preferred.
In addition, Mn shows a number average molecular weight.

[(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 the component (B ′) include those exemplified in the description of the component (B) of the positive resist composition according to the first aspect of the present invention.
(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, as the component (B ′), an onium salt having a fluorinated alkyl sulfonate ion as an anion and an onium salt having the general formula (b1-12) as an anion are preferably used in combination. As the onium salt having the general formula (b1-12) as an anion, compounds represented by the formulas (b-12-1) to (b-12-18) are more preferably used, and the formula (b-12) It is particularly preferable to use the compound represented by -1).
Content of (B ') component in a 1st positive resist composition is 0.5-30 mass parts with respect to 100 mass parts of (A') component, Preferably it is 1-10 mass parts. 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]
In the first positive resist composition, a nitrogen-containing organic compound (D ′) (hereinafter referred to as “(D ′)” component) is further added as an optional component in order to improve the resist pattern shape, the stability over time. ) Can be blended.
Since a wide variety of components (D ′) have already been proposed, any known component may be used. Examples of the component (D ′) include those exemplified in the description of the component (D) of the positive resist composition according to the first embodiment of the present invention.
As the component (D ′), these nitrogen-containing organic compounds may be used alone or in combination of two or more.
The component (D ′) is usually used in the range of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A ′).

[(E ′) component]
The first positive resist composition includes an organic carboxylic acid, a phosphorus oxo acid, and derivatives thereof as optional components for the purpose of preventing sensitivity deterioration, improving the resist pattern shape, stability with time, etc. At least one compound (E ′) selected from the group consisting of (hereinafter referred to as “component (E ′)”) can be blended.
Since a wide variety of components (E ′) have already been proposed, any known component may be used. Examples of the component (E ′) include the same components as those exemplified in the description of the component (E) of the positive resist composition according to the first embodiment of the present invention.
As the component (E ′), these compounds may be used alone or in combination of two or more.
As the component (E ′), an organic carboxylic acid is preferable, and salicylic acid is particularly preferable.
(E ') component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A') component.

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

[(S ′) component]
The first positive resist composition 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. Or it can select and use 2 or more types suitably. Examples of the component (S ′) include those exemplified in the description of the component (S3) of the positive resist composition.
These (S ′) components may be used alone or in combination of two or more.

In the first positive resist composition, the component (S ′) is preferably propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), or EL.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is also preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S ′), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.

  The amount of the component (S ′) used as a whole is not particularly limited, but an amount that makes the first positive resist composition become a liquid having a concentration that can be applied onto the support is used.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
The following copolymers (A) -11-12, 21-28, 28-1, 27-1, 27-2, 31-37 are prepared by adding the following monomers (1) to (8) to known drop weights. It was synthesized by copolymerization using a legal method.
Mw and Mw / Mn of copolymer (A) -11-12, 21-28, 28-1, 27-1, 27-2, 31-37 were measured by GPC.
In formulas (A) -11-12, 21-28, 28-1, 27-1, 27-2, 31-37, the numbers attached to the lower right of () indicate the proportion (mol%) of each structural unit. Show.

<Synthesis Example 1: Synthesis of Copolymer (A) -11>
5.85 g of monomer (1), 7.65 g of monomer (2), 7.08 g of monomer (3) were dissolved in 95.03 g of methyl ethyl ketone. To this solution, 3.02 mmol of V-601 (polymerization initiator) manufactured by Wako Pure Chemical Industries, Ltd. was added and dissolved. The resultant was dropwise added to 3.00 g of methyl ethyl ketone heated to 75 ° C. in a nitrogen atmosphere over 6 hours. After completion of dropping, the reaction solution was heated and stirred for 1 hour, and then the reaction solution was cooled to room temperature. Thereafter, the operation of dropping the reaction solution into a large amount of methanol / water mixed solution and precipitating the reaction product was repeated three times. The reaction product thus obtained was dried under reduced pressure at room temperature to obtain a white powder. As a result of performing GPC measurement about the obtained resin (A) -11, the mass average molecular weight (Mw) was 7000, and the dispersity (Mw / Mn) was 1.72.

Copolymers (A) -12, (A) -21-28, 28-1, 27-1, 27-2, 31-37 were synthesized in the same manner as in Synthesis Example 1.

<Examination of Solubility of Copolymer (A) -11-12, 21, 31-33 in Organic Solvent>
PGMEA, isobutanol (IBA), diisopentyl ether (DIAE), 1,8-cineol (CNL) were prepared so that the copolymers (A) -11 to 12, 21, 31 to 33 were each in 1% solution. ) And mixed to confirm whether or not to dissolve. The obtained results are shown in Table 1. In the table, “◯” means dissolved, and “x” means not dissolved. All copolymers were dissolved well in PGMEA, but in isobutanol, the structural unit (a0-1) represented by the general formula (a0-1) and the general formula (a0-2) Only the copolymer (A) -21 having the structural unit (a0-2) represented was dissolved. Similarly, only copolymer (A) -31 was dissolved in diisopentyl ether. On the other hand, four types of copolymers other than the copolymers (A) -11 to (A) -12 were dissolved in 1,8-cineole.
From this result, it is clear that having the structural units (a0-1) and (a0-2) improves the solubility of the positive resist composition in an alcohol-based organic solvent.

<Examination of Solubility of Copolymer (A) -11-12, 21-28, 28-1, 27-1, 27-2, 34-37 in Isobutanol and 4-Methyl-2-pentanol>
To make a 50% solution, 0.1 g of each resin powder of copolymer (A) -11-12, 21-28, 28-1, 27-1, 27-2, 34-37, 0.1 g It was confirmed whether or not isobutanol was added and mixed to dissolve. When not dissolved, 0.2 g of isobutanol was further added and mixed so as to obtain a 25% solution, and it was confirmed whether or not it was dissolved. When not dissolved, 0.6 g of isobutanol was further added and mixed so that a 10% solution was obtained, and it was confirmed whether or not it was dissolved. When not dissolved, 1.0 g of isobutanol was further added and mixed so as to obtain a 5% solution, and it was confirmed whether or not it was dissolved. When not dissolved, 3.0 g of isobutanol was further added and mixed so as to be a 2% solution, and it was confirmed whether or not it was dissolved. When not dissolved, 5.0 g of isobutanol was further added and mixed so as to obtain a 1% solution, and it was confirmed whether or not it was dissolved. The obtained results are shown in Table 2. In the table, “◯” or “x” has the same meaning as in Table 1. As a result, it was confirmed that all the copolymers (A) -11 to 12 and 34 to 37 were not dissolved at all concentrations. On the other hand, the copolymers (A) -21 to 28, 28-1, 27-1, and 27-2 increase in solubility in isobutanol as the solution concentration is decreased. It was confirmed that this copolymer was dissolved in isobutanol.
Similarly, the solubility of the copolymers (A) -28 and 28-1 in 4-methyl-2-pentanol was evaluated. As a result, it was confirmed that in the 2% solution, all the copolymers were dissolved in 4-methyl-2-pentanol.

<Preparation of positive resist composition>
The components shown in Table 3 and Table 4 were mixed and dissolved to prepare a positive resist composition solution.

Each abbreviation in Table 3 and Table 4 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(A) -11: a polymer compound represented by the formula (A) -11.
(A) -21: a polymer compound represented by the formula (A) -21.
(A) -22: a polymer compound represented by the formula (A) -22.
(A) -24: a polymer compound represented by the formula (A) -24.
(A) -27: a polymer compound represented by the formula (A) -27.
(A) -28: a polymer compound represented by the formula (A) -28.
(A) -28-1: a polymer compound represented by the formula (A) -28-1.
(A) -27-1: a polymer compound represented by the formula (A) -27-1.
(A) -27-2: a polymer compound represented by the formula (A) -27-2.
(B) -1: Triphenylsulfonium heptafluoro-n-propanesulfonate.
(B) -2: An acid generator represented by the chemical formula (b-12-1).
(B) -3: Triphenylsulfonium trifluoromethanesulfonate.
(B) -4: 4-methylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate.
(B) -5: An acid generator represented by the following chemical formula (B) -5.
(B) -6: An acid generator represented by the following chemical formula (B) -6.
(B) -7: 4-methylphenyldiphenylsulfonium trifluoromethanesulfonate.
(B) -8: An acid generator represented by the following chemical formula (B) -8.
(B) -9: An acid generator represented by the following chemical formula (B) -9.

(D) -1: tri-n-pentylamine.
(D) -2: Triethanolamine.
(E) -1: salicylic acid.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.
(S) -2: PGMEA.
(S) -3: PGME.
(S) -4: Isobutanol.
(S) -5: 4-methyl-2-pentanol.

<Resist pattern formation by double patterning>
As shown in Tables 5 and 6 below, the positive resist composition for forming the first resist film and the positive resist composition for forming the second resist film were obtained in Tables 3 and 4 above. A resist pattern was formed by a double patterning method using each of the obtained resist compositions. In Tables 5 and 6 below, “first resist film” is a positive resist composition that forms a first resist film, and “second resist film” is a positive resist that forms a second resist film. Each composition means.
First, an organic antireflection film composition “ARC29” (trade name, manufactured by Brewer Science Co., Ltd.) is applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a thickness of 77 nm was formed.
On the organic antireflection film, a positive resist composition for forming a first resist film was applied using a spinner, and 110 on Examples 1-5 and Comparative Examples 1-15 on a hot plate. A resist film having a film thickness of 120 nm (first resist film) is obtained by performing pre-baking (PAB) treatment under the conditions of 60 ° C. for 60 seconds and 90 ° C. for 60 seconds in Examples 6 to 22 and drying. Formed.
Next, an ArF excimer laser (193 nm) was applied to the first resist film by an ArF exposure apparatus NSR-S302 (Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). Irradiation selectively through a mask pattern (6% halftone). And in Examples 1-5 and Comparative Examples 1-15, under the conditions of 110 ° C. for 60 seconds, and in Examples 6-22 under the conditions of 90 ° C. for 60 seconds, post-exposure heating (PEB) treatment is performed, Further, the film was developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ° C. for 30 seconds, then rinsed with pure water for 30 seconds, and then shaken and dried. As a result, a line-and-space resist pattern (referred to as an L / S pattern) having a line width of 120 nm and a pitch of 480 nm was formed. Tables 5 and 6 show the optimum exposure amount (Eop) (unit: mJ / cm ² (energy amount per unit area)) at which an L / S pattern having a line width of 120 nm and a pitch of 480 nm is formed.

Subsequently, a positive resist composition for forming a second resist film is applied onto the substrate on which the 1: 3 L / S pattern has been formed using a spinner, and is heated at 90 ° C. for 60 seconds on a hot plate. A pre-baking (PAB) process was performed and dried to form a positive resist film (second resist film) having a thickness of 120 nm.
Next, an ArF excimer laser (193 nm) was applied to the second resist film using an ArF exposure apparatus NSR-S302 (Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). Was selectively irradiated through a mask pattern (6% halftone). Then, post-exposure heating (PEB) treatment is performed at 90 ° C. for 60 seconds, and further development is performed at 23 ° C. with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds, and then 30 Water rinsing was performed using pure water for 2 seconds, and then shaken off and dried.
In addition, Tables 5 and 6 show the exposure amounts at that time.

The results of the above double patterning are shown in Tables 5 and 6. In the table, “◯” indicates that a pattern in which a 120 nm line pattern is mixed between lines of an L / S pattern having a line width of 120 nm and a pitch of 480 nm can be obtained, and “×” indicates that the pattern It is shown that each could not be formed. That is, in Examples 1 to 22 using the resist compositions 2-1 to 2-22, which are the resist compositions of the present invention, as the positive resist composition for forming the second resist film, the line width is 120 nm and the pitch. Although it was possible to obtain a pattern in which a 120 nm line pattern was mixed between L / S pattern lines of 480 nm, the resist compositions 3-1 to 3-5, 4-1 to 4-5, In Comparative Examples 1 to 15 using 5-1 to 5-5, the lower layer was dissolved and a pattern could not be formed.
From these results, the first resist pattern formed on the support was obtained by using the positive resist composition of the present invention for the formation of the second resist film as in the resist pattern forming method of the present invention. It is clear that a resist pattern by double patterning can be formed stably without dissolving.

Claims (6)

A step of applying a positive resist composition on the support to form a first resist film, and selectively exposing the first resist film and developing with alkali to form a first resist pattern A step of forming a second resist film by applying a positive resist composition on the support on which the first resist pattern is formed; and selectively exposing the second resist film. And a positive resist pattern forming method including a step of forming a resist pattern by alkali development, a positive resist composition used for forming the second resist film,
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, are dissolved in an organic solvent (S).
The organic solvent (S) is an organic solvent that does not dissolve the first resist film,
The resin component (A) includes a structural unit (a0-1) represented by the following general formula (a0-1) and a structural unit (a0-2) represented by the following general formula (a0-2). A positive resist composition comprising:

[In formula (a0-1), R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; Y ¹ represents an aliphatic cyclic group; Z represents a tertiary alkyl group-containing group or an alkoxyalkyl group. A is an integer of 1 to 3, b is an integer of 0 to 2, and a + b = 1 to 3; c, d, and e are each independently an integer of 0 to 3. In the formula (a0-2), R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; Y ³ is an alkylene group or an aliphatic cyclic group; g and h are each independently I is an integer from 0 to 3; i is an integer from 1 to 3; ]   The positive resist composition according to claim 1, wherein the organic solvent (S) is an alcohol-based organic solvent.   The ratio of the said structural unit (a0-1) in the said resin component (A) is 1-40 mol% with respect to the sum total of all the structural units which comprise the said resin component (A). A positive resist composition.   The positive resist composition according to claim 1, wherein the resin component (A) further has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting 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 applying a positive resist composition on the support to form a first resist film, and selectively exposing the first resist film and developing with alkali to form a first resist pattern And a step of forming a second resist film by applying the positive resist composition according to any one of claims 1 to 5 on the support on which the first resist pattern is formed. And a step of selectively exposing the second resist film and performing alkali development to form a resist pattern.