JP2008309888A - Positive resist composition and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition which is superior in resolution, and to provide a resist pattern forming method. <P>SOLUTION: The positive resist composition contains a resin component (A), whose solubility in an alkali developer increases by acidic action and an acid generator component (B) which generates an acid upon exposure to light, wherein the component (A) contains a constitutional unit (a1), derived from a hydroxystyrene and a constitutional unit (a2) having an acetal type acid-dissociable dissolution inhibiting group, and the component (B) contains an acid generator (B1), comprising a compound represented by a cation having a 9-phenylthiocarbazole structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

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

  Resist materials are required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions. As a resist material that satisfies such requirements, a chemically amplified resist containing a base resin whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains, as a base resin, a resin whose solubility in an alkaline developer is increased by the action of an acid and an acid generator, and from the acid generator by exposure during resist pattern formation. When the acid is generated, the exposed portion becomes soluble in the alkaline developer.

Up to now, as the base resin of chemically amplified resist, polyhydroxystyrene (PHS), which is highly transparent to KrF excimer laser (248 nm), and a resin whose hydroxyl group is protected with an acid dissociable, dissolution inhibiting group (PHS resin) Has been used. However, since the PHS resin has an aromatic ring such as a benzene ring, the transparency to light having a wavelength shorter than 248 nm, for example, 193 nm, is not sufficient. For this reason, a chemically amplified resist having a PHS resin as a base resin component has drawbacks such as low resolution in a process using 193 nm light, for example.
Therefore, as a resist base resin currently used in ArF excimer laser lithography and the like, it has a structural unit generally derived from a (meth) acrylic acid ester in its main chain because of its excellent transparency near 193 nm. Resin (acrylic resin) is used. In the case of the positive type, the resin includes a structural unit derived from a (meth) acrylic acid ester containing a tertiary alkyl ester type acid dissociable, dissolution inhibiting group containing an aliphatic polycyclic group, for example, 2-alkyl. A resin having a structural unit derived from 2-adamantyl (meth) acrylate or the like is mainly used (for example, see Patent Document 1).

  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. “(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. “(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.

On the other hand, various acid generators used in chemically amplified resists have been proposed so far, such as onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, Diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like are known. Currently, an acid generator containing a triphenylsulfonium skeleton, a dinaphthyl monophenylsulfonium skeleton, or the like is used as the acid generator (see Patent Document 2).
JP 2003-241385 A Japanese Patent Laid-Open No. 2005-37888

In recent years, the miniaturization of resist patterns has further progressed, and the demand for high resolution has further increased for resist materials.
For example, since lithography with an electron beam (EB) or extreme ultraviolet (EUV) is aimed at forming a fine pattern of several tens of nanometers, the smaller the resist pattern size, the more the conventional chemically amplified positive resist composition. In products, further improvement in resolution is required.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the resist pattern formation method using the positive resist composition excellent in the resolution, and this positive resist composition .

As a result of intensive studies, the present inventors have solved the above problem by using a resin component containing two specific structural units as a base resin and an acid generator having a specific cation moiety. As a result, the present invention has been completed.
That is, the first aspect of the present invention is a positive resist composition containing a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure. The resin component (A) includes a structural unit (a1) derived from hydroxystyrene and a structural unit (a2) represented by the following general formula (a2-1) or (a2-2): And the acid generator component (B) contains an acid generator (B1) composed of a compound represented by the following general formula (b1-1). .

［式（ａ２−１）中、Ｒは水素原子、炭素数１〜５の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^１およびＲ^２はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基であり；Ｙ^１は炭素数１〜５の低級アルキル基または１価の脂肪族環式基であり；ｎ_２１は０〜３の整数である。式（ａ２−２）中、Ｒは前記と同じであり；Ｒ^３およびＲ^４はそれぞれ独立して水素原子または炭素数１〜５の低級アルキル基であり；Ｒ^５はアルキレン基または２価の脂肪族環式基であり；Ｙ^２は炭素数１〜５の低級アルキル基または１価の脂肪族環式基であり；ｎ_２２は０〜３の整数である。］

[In Formula (a2-1), R represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms or a halogenated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or 1 to 5 carbon atoms; Y ¹ is a lower alkyl group having 1 to 5 carbon atoms or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0 to 3. In formula (a2-2), R is as defined above; R ³ and R ⁴ are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; R ⁵ is an alkylene group or a divalent group. An aliphatic cyclic group; Y ² is a lower alkyl group having 1 to 5 carbon atoms or a monovalent aliphatic cyclic group; and n ₂₂ is an integer of 0 to 3. ]

［式（ｂ１−１）中、Ｒ^４１、Ｒ^４２およびＲ^４３はそれぞれ独立してハロゲン原子、ハロゲン化アルキル基、アルキル基、アセチル基、アルコキシ基、カルボキシ基、またはヒドロキシアルキル基であり；ｎ_１、ｎ_２およびｎ_３はそれぞれ独立して０〜３の整数である。Ｘ⁻はアニオンである。］

[In formula (b1-1), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a halogen atom, a halogenated alkyl group, an alkyl group, an acetyl group, an alkoxy group, a carboxy group or a hydroxyalkyl group; n ₁ , n ₂ and n ₃ are each independently an integer of 0 to 3. X ⁻ is an anion. ]

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

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.
“Lower alkyl group” means an alkyl group having 1 to 5 carbon atoms.
The term “exposure” includes not only light irradiation but also general irradiation of radiation such as an electron beam.

  According to the present invention, it is possible to provide a positive resist composition having excellent resolution and a resist pattern forming method using the positive resist composition.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid (hereinafter referred to as “component (A)”), and an acid generator component that generates an acid upon exposure. (B) (hereinafter referred to as component (B)).
In the positive resist composition of the present invention, the component (A) is insoluble in an alkali developer before exposure, and when the acid generated from the component (B) by exposure acts, The solubility in an 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, alkali development can be performed.

<(A) component>
In the present invention, the component (A) includes the structural unit (a1) derived from hydroxystyrene and the structural unit (a2) represented by the general formula (a2-1) or (a2-2). .

[Structural unit (a1)]
The structural unit (a1) is a structural unit derived from hydroxystyrene. By using a combination of the component (A) containing the structural unit (a1) and the structural unit (a2) described later and the acid generator (B1) described later, a resist pattern having excellent resolution can be formed. . Further, when the component (A) includes the structural unit (a1), dry etching resistance is improved. Furthermore, the structural unit (a1) also has the advantage that the raw material hydroxystyrene is readily available and is inexpensive.
In the present specification and claims, the term “hydroxystyrene” refers to hydroxystyrene, those obtained by substituting the hydrogen atom at the α-position of hydroxystyrene with another substituent such as an alkyl group, and derivatives thereof. Include concepts.
The α-position (α-position carbon atom) is a carbon atom to which a benzene ring is bonded unless otherwise specified.
The “structural unit derived from hydroxystyrene” means a structural unit formed by cleavage of the ethylenic double bond of hydroxystyrene.
As a suitable thing of a structural unit (a1), the structural unit represented by the following general formula (a1-1) can be illustrated.

［式（ａ１−１）中、Ｒ’は水素原子または低級アルキル基であり；Ｒ^６は低級アルキル基であり；ｐは１〜３の整数であり；ｑは０〜２の整数である。］

[In Formula (a1-1), R ′ represents a hydrogen atom or a lower alkyl group; R ⁶ represents a lower alkyl group; p represents an integer of 1 to 3; and q represents an integer of 0 to 2. ]

In the general formula (a1-1), the lower alkyl group for R ′ is an alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, and an n-butyl group. , An isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group and the like, and a linear or branched alkyl group, and a methyl group is preferable among them.
R ′ is preferably a hydrogen atom or a lower alkyl group, particularly preferably a hydrogen atom or a methyl group.

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

q is an integer of 0-2. Among these, q is preferably 0 or 1, and is preferably 0 industrially.
As the lower alkyl group for R ^{6, the same as} the lower alkyl group for R ′ can be exemplified.
When q is 1, the substitution position of R ⁶ may be any of the o-position, m-position, and p-position. When q is 2, arbitrary substitution positions can be combined. The plurality of R ⁶ may be the same or different.

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

[Structural unit (a2)]
The structural unit (a2) is a structural unit represented by the general formula (a2-1) or (a2-2). By using a combination of the component (A) containing the structural unit (a2) and the structural unit (a1) and an acid generator (B1) described later, a resist pattern having excellent resolution can be formed.
Hereinafter, the structural unit represented by the general formula (a2-1) is referred to as a structural unit (a2-1). Moreover, the structural unit represented by the general formula (a2-2) is referred to as a structural unit (a2-2).
A group represented by the formula —C (R ¹ ) (R ² ) —O— (CH ₂ ) _n21 —Y ¹ in the general formula (a2-1), and a formula —C (R in the general formula (a2-2); ³ ) The group represented by (R ⁴ ) —O— (CH ₂ ) _n22 —Y ² is a so-called acetal type acid dissociable, dissolution inhibiting group.
The structural unit (a2-1) and the structural unit (a2-2) each have a structure in which the acetal type acid dissociable, dissolution inhibiting group is bonded to an oxygen atom at a carbonyloxy group (—C (O) —O—) terminal. It is common in having. In such a structure, when an acid is generated from the component (B) by exposure, the bond between the acid dissociable, dissolution inhibiting group and the oxygen atom at the terminal of the carbonyloxy group is broken by the action of the acid.
Here, in the present specification and claims, “acid dissociation” means that it can be dissociated from the component (A) by the action of an acid generated from the component (B) during exposure.
The “dissolution-inhibiting group” has an alkali dissolution inhibiting property that makes the entire component (A) insoluble in an alkali developer before dissociation, and after dissociation, the entire component (A) is soluble in an alkali developer. It means that it is a group to change to.
Therefore, the component (A) containing the structural unit (a2) is insoluble in the alkali developer before exposure, and when the acid generated from the component (B) by exposure acts, the acetal type acid dissociation property The dissolution inhibiting group is dissociated, whereby the solubility of the entire component (A) in the alkali developer is increased 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, alkali development can be performed.

In general formula (a2-1), R represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms, or a halogenated lower alkyl group. As the lower alkyl group for R, the same as the lower alkyl group for R ′ in formula (a1-1) can be mentioned.
R is preferably a hydrogen atom, a lower alkyl group or a fluorinated lower alkyl group, and particularly preferably a hydrogen atom or a methyl group in terms of industrial availability.
R ¹ and R ² are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. Examples of the lower alkyl group for R ¹ and R ² include the same as the lower alkyl group for R ′ in the general formula (a1-1). From the viewpoint of industrial availability, preferable.
Since R ¹ and R ² are excellent in the effects of the present invention, at least one of them is preferably a hydrogen atom, and more preferably both are hydrogen atoms.
n ₂₁ is an integer of 0 to 3, preferably 0 or 1, and most preferably 0.

Y ¹ is a lower alkyl group having 1 to 5 carbon atoms or a monovalent aliphatic cyclic group.
As the lower alkyl group for Y ^{1, the same as} the lower alkyl group for R ′ in general formula (a1-1) above can be used.
The monovalent aliphatic cyclic group for Y ¹ is appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in many resist resins for ArF excimer lasers. be able to.
Here, in the claims and the specification, the “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The aliphatic cyclic group for Y 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, a hydrophilic group, and the like. Examples of the hydrophilic group include ═O, —COOR ″ (R ″ is an alkyl group), alcoholic hydroxyl group, —OR ″ (R ″ is an alkyl group), imino group, amino group and the like, and are easily available. Therefore, ═O or alcoholic hydroxyl group is preferable.
The structure of the basic ring (basic ring) excluding the substituent in the aliphatic cyclic group may be a ring consisting of carbon and hydrogen (hydrocarbon ring), and the carbon atoms constituting the hydrocarbon ring A heterocyclic ring partially substituted with a hetero atom such as a sulfur atom, an oxygen atom, or a nitrogen atom may be used. For the effect of the present invention, the basic ring in Y ¹ is preferably a hydrocarbon ring.
As the hydrocarbon ring, a resist resin for ArF excimer laser, KrF excimer laser, etc. can be used by appropriately selecting from among many proposed resins. Specifically, monocycloalkane or bicyclo Examples include polycycloalkanes such as alkanes, tricycloalkanes, and tetracycloalkanes. Examples of the monocycloalkane include cyclopentane and cyclohexane. Examples of the polycycloalkane include adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, isobornane, tricyclodecane, and tetracyclododecane. Among these, cyclohexane, cyclopentane, adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, and tetracyclododecane are industrially preferable, and adamantane is more preferable.

Preferred examples of the group represented by the formula —C (R ¹ ) (R ² ) —O— (CH ₂ ) _n21 —Y ¹ include groups represented by the following formulas (11) to (22). As mentioned.

In general formula (a2-2), R is the same as defined above, R ³ and R ⁴ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and Y ² has 1 to 5 carbon atoms. A lower alkyl group or a monovalent aliphatic cyclic group, and n ₂₂ is an integer of 0 to 3.
Examples of R, R ³ , R ⁴ , n ₂₂ and Y ² are the same as R, R ¹ , R ² , n ₂₁ and Y ¹ in general formula (a2-1).
R ⁵ is an alkylene group or a divalent aliphatic cyclic group.
When R ⁵ is an alkylene group, it is preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and 1 to 3 carbon atoms. Most preferably it is.
When R ⁵ is an aliphatic cyclic group, the aliphatic cyclic group may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the aliphatic cyclic group for R ⁵ 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 for R ⁵ is preferably a polycyclic group.
Specific examples of the aliphatic cyclic group for R ⁵ include, for example, a monocycloalkane or bicycloalkane which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated lower alkyl group. And groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as tricycloalkane or tetracycloalkane. Specifically, two hydrogen atoms are removed from a group obtained by removing two or more hydrogen atoms from a monocycloalkane such as cyclopentane or cyclohexane, or from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Examples include groups that have been removed.
As the aliphatic cyclic group for Y ² , a group represented by general formula (y-1) shown below is particularly preferable.

［式中、ｍは０または１であり、好ましくは１である。］

[Wherein, m is 0 or 1, preferably 1. ]

Specific examples of the structural unit (a2-1) represented by the general formula (a2-1) include structural units represented by the following formulas (a1-2-1) to (a1-239). It is done.
Specific examples of the structural unit (a2-2) represented by the general formula (a2-2) include structural units represented by the following formulas (a1-4-1) to (a1-4-42). It is done.

  As the structural unit (a2), the structural unit (a2-1) is more preferable because the effects of the present invention are more excellent. Among them, the above formula (a1-2-9), formula (a1-2-10), formula (a1-2-13), formula (a1-2-14), formula (a1-2-15), And at least one structural unit selected from structural units represented by formula (a1-2-16) is particularly preferred, and a configuration represented by formula (a1-2-9) or formula (a1-2-10) Most preferred is at least one structural unit selected from units.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the component (A) is preferably from 5 to 50 mol%, more preferably from 10 to 40 mol%, more preferably from 15 to 35, based on the total of all structural units constituting the component (A). More preferred is mol%. When it is at least the lower limit of this range, a pattern can be obtained when it is a positive resist composition, and when it is at most the upper limit, the balance with other structural units is good.

[Other structural units]
In addition to the structural units (a1) and (a2), the component (A) may further have a structural unit (a4) derived from styrene.
In the present invention, the structural unit (a4) is not essential, but when it is contained, the solubility in an alkali developer can be adjusted. Moreover, since dry etching tolerance improves, it is preferable.
In this specification, “styrene” is a concept including styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as an alkyl group.
“Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.
As a suitable thing of a structural unit (a4), the structural unit represented by the following general formula (a4-1) can be illustrated.

［式（ａ４−１）中、Ｒ’は前記と同じであり；Ｒ^７は炭素数１〜５の低級アルキル基であり；ｒは０〜３の整数である。］

[In formula (a4-1), R ′ is the same as above; R ⁷ is a lower alkyl group having 1 to 5 carbon atoms; and r is an integer of 0 to 3. ]

In the general formula (a4-1), R ′ and R ⁷ are the same as R ′ and R ⁶ in the formula (a1-1), respectively.
r is an integer of 0 to 3, preferably 0 or 1, and industrially particularly preferably 0.
When r is 1, the substitution position of R ⁷ may be any of the o-position, m-position and p-position of the phenyl group.
When r is 2 or 3, any substitution position can be combined. The plurality of R ⁷ may be the same or different.

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

The component (A) may contain a structural unit (a5) other than the structural units (a1), (a2), and (a4) as long as the effects of the present invention are not impaired.
The structural unit (a5) is not particularly limited as long as it is another structural unit not classified into the above structural units (a1), (a2), and (a4). A structural unit derived from an acrylate ester containing a formula group, a structural unit derived from an acrylate ester containing a lactone-containing cyclic group, or a structural unit derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group For example, a number of hitherto known materials can be used as resist resins for ArF excimer laser, KrF excimer laser (preferably for ArF excimer laser), and the like.

In the present invention, the component (A) is a resin component containing at least the structural unit (a1) and the structural unit (a2). Examples of such resin components include copolymers having structural units (a1) and (a2); copolymers having structural units (a1), (a2) and (a4).
(A) A component may be used individually by 1 type and may use 2 or more types together.
(A) As a component, what contains the copolymer which has a 2 types of structural unit shown by the following general formula (A-11) especially is preferable.

［式中、Ｒ’およびＲは前記と同じであり；ｎ_１５は０または１である。］

[Wherein, R ′ and R are as defined above; n ₁₅ is 0 or 1; ]

In formula (A-11), R ′ is preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.
R is preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.
n ₁₅ is particularly preferably 0.
The bonding position between adamantane and —CH ₂ —O— (CH ₂ ) _n15 — is preferably the 1- or 2-position of adamantane, and more preferably the 2-position.

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. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom has an LWR (line width roughness: a phenomenon in which the line width of a line pattern becomes nonuniform). Effective for reduction. 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 (GPC)) is not particularly limited, preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 5000. 20000 is most preferred. If it is below the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and if it is above the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) is not particularly limited, and is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. . In addition, Mn shows a number average molecular weight.
In the positive resist composition of the present invention, the content of the component (A) may be adjusted according to the resist film thickness to be formed.

<(B) component>
In the positive resist composition of the present invention, the component (B) contains an acid generator (B1) (hereinafter referred to as the component (B1)) composed of a compound represented by the following general formula (b1-1). .
Component (B) contains component (B1), so it has good solubility in general resist solvents such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and ethyl lactate (EL). It becomes. Furthermore, by using the component (B1) in combination with the component (A) including the structural unit (a1) and the structural unit (a2), a resist pattern with excellent resolution can be formed.

［式（ｂ１−１）中、Ｒ^４１、Ｒ^４２およびＲ^４３はそれぞれ独立してハロゲン原子、ハロゲン化アルキル基、アルキル基、アセチル基、アルコキシ基、カルボキシ基、またはヒドロキシアルキル基であり；ｎ_１、ｎ_２およびｎ_３はそれぞれ独立して０〜３の整数である。Ｘ⁻はアニオンである。］

[In formula (b1-1), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a halogen atom, a halogenated alkyl group, an alkyl group, an acetyl group, an alkoxy group, a carboxy group or a hydroxyalkyl group; n ₁ , n ₂ and n ₃ are each independently an integer of 0 to 3. X ⁻ is an anion. ]

In the general formula (b1-1), R ⁴¹ , R ⁴² and R ⁴³ are each independently a halogen atom, a halogenated alkyl group, an alkyl group, an acetyl group, an alkoxy group, a carboxy group, or a hydroxyalkyl group. .
In R ⁴¹ , R ⁴² and R ⁴³ , the alkyl group is preferably a lower alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group, a methyl group, an ethyl group, or a propyl group. , An isopropyl group, an n-butyl group, a tert-butyl group, a tert-pentyl group, or an isopentyl group, more preferably a methyl group.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a linear or branched alkoxy group, and even more preferably a methoxy group or an ethoxy group.
The hydroxyalkyl group is preferably a group in which one or more hydrogen atoms of the above alkyl group are substituted with a hydroxy group, and examples thereof include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl 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 halogenated alkyl group is preferably a halogenated alkyl group having 1 to 5 carbon atoms, more preferably a halogenated alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, a trifluoromethyl group, More preferably, it is a pentafluoroethyl group.

In general formula (b1-1), _{n 1} is an integer of 0 to 3, preferably 0 to 2, more preferably 0 or 1, more preferably from 0.
n ₂ and n ₃ each independently represents an integer of 0 to 3, preferably each independently 0 or 1, more preferably each independently 0, and still more preferably both 0 .
When the codes n _{1 to} n ₃ attached to R ^{41 to} R ⁴³ are integers of 2 or more, the plurality of R ^{41 to} R ⁴³ may be the same or different.

In the general formula (b1-1), X ⁻ represents an anion.
The anion portion of X ⁻ is not particularly limited, and those known as the anion portion of the onium salt acid generator can be appropriately used. For example, an anion represented by the general formula “R ¹⁴ SO ₃ ^— (wherein R ¹⁴ represents a linear, branched or cyclic alkyl group or halogenated alkyl group)”, or a general formula “R ¹ ′ —O—Y ¹ ′ —SO ₃ ^— (R ¹ ′ is a monovalent aliphatic hydrocarbon group, monovalent aromatic organic group, or hydroxyalkyl group; Y ¹ ′ may be fluorine-substituted. An anion represented by an alkylene group having 1 to 4 carbon atoms can be used.

In the general formula “R ¹⁴ SO ₃ ^— ”, R ¹⁴ represents a linear, branched, or cyclic alkyl group, a halogenated alkyl group, an aryl group, or an alkenyl group.
The linear or branched alkyl group as R ¹⁴ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and 1 to 4 carbon atoms. Most preferred.
The cyclic alkyl group as R ¹⁴ preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
Among the above, R ¹⁴ is preferably a halogenated alkyl group. That is, in the general formula (b1-1), X ⁻ is preferably a halogenated alkyl sulfonate ion. The alkyl halide is one in which part or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms. Here, examples of the halogenated alkyl include those in which a halogen atom is substituted for the same as the “alkyl group” in R ⁴¹ , R ⁴² and R ⁴³ . Examples of the halogen atom to be substituted include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In the alkyl halide, 50 to 100% of the total number of hydrogen atoms are preferably substituted with halogen atoms, and more preferably all are substituted.
Here, the halogenated alkyl group is preferably a fluorinated alkyl group. The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of the number of fluorine atoms substituted by fluorination to the total number of hydrogen atoms in the alkyl group before fluorination, the same shall apply hereinafter) is preferably 10 to 100. %, More preferably 50 to 100%, and in particular, those in which all hydrogen atoms are substituted with fluorine atoms are preferred because the strength of the acid becomes strong.
The aryl group as R ¹⁴ is preferably an aryl group having 6 to 20 carbon atoms which may have a substituent. Examples of the substituent that may have include a halogen atom, a hetero atom, and an alkyl group. You may have two or more substituents.
The alkenyl group as R ¹⁴ is preferably an alkenyl group having 2 to 10 carbon atoms which may have a substituent. Examples of the substituent that may have include a halogen atom, a hetero atom, and an alkyl group. You may have two or more substituents.

In the general formula “R ¹ ′ —O—Y ¹ ′ —SO ₃ ^— ”, R ¹ ′ is a monovalent aliphatic hydrocarbon group, aromatic organic group, or hydroxyalkyl group; Y ¹ ′ is fluorine. It is a C1-C4 alkylene group which may be substituted.

Examples of the monovalent aliphatic hydrocarbon group for R ¹ ′ include, for example, a linear, branched or cyclic monovalent saturated hydrocarbon group having 1 to 15 carbon atoms, or a straight chain having 2 to 5 carbon atoms. A linear or branched monovalent aliphatic unsaturated hydrocarbon group may be mentioned.

Examples of the linear monovalent saturated hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decanyl group.
Examples of the branched monovalent saturated hydrocarbon group include 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1 -Ethylbutyl group, 2-ethylbutyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group and the like can be mentioned.
The cyclic monovalent saturated hydrocarbon group may be either a polycyclic group or a monocyclic group, for example, one from a polycycloalkane such as a monocycloalkane, a bicycloalkane, a tricycloalkane, or a tetracycloalkane. And a group in which a hydrogen atom is removed. More specifically, one hydrogen atom was removed from a monocycloalkane such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane, and a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Groups and the like.
Examples of the linear monovalent unsaturated hydrocarbon group include a propenyl group (allyl group) and a butynyl group.
Examples of the branched monovalent unsaturated hydrocarbon group include a 1-methylpropenyl group and a 2-methylpropenyl group.
3-4 are preferable and, as for carbon number of the monovalent | monohydric aliphatic hydrocarbon group of R < ¹ '>, 3 is especially preferable.

Examples of monovalent aromatic organic groups for R ¹ ′ include aromatic hydrocarbon rings such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. An aryl group in which one hydrogen atom is removed; a heteroaryl group in which part of the carbon atoms constituting the ring of these aryl groups is substituted with a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. These aryl groups and heteroaryl groups 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 hydroxyalkyl group for R ¹ ′ is a group in which at least one hydrogen atom of a linear, branched or cyclic monovalent saturated hydrocarbon group is substituted with a hydroxyl group. Among these, a linear or branched monovalent saturated hydrocarbon group in which one or two hydrogen atoms are substituted with a hydroxyl group is preferable. Specific examples include 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 2,3-dihydroxypropyl group, and the like.
3-10 are preferable, as for carbon number of the monovalent | monohydric hydroxyalkyl group of R < ¹ '>, 3-8 are more preferable, and 3-6 are especially preferable.

Examples of the optionally substituted fluorine-substituted alkylene group for Y ¹ ′ include —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 _{) -, - 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) -; and the like.

Moreover, as the C1-C4 alkylene group which may be fluorine-substituted as Y ¹ ′, a carbon atom bonded to S is preferably 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 can be mentioned, et al That.
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.

In the general formula (b1-1), in addition to the above, X ⁻ may be an anion represented by the following general formula (b-3), an anion represented by the following general formula (b-4), or the like. it can.

［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

In the general formula (b-3), 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 preferably has 2 carbon atoms. -6, more preferably 3-5 carbon atoms, most preferably 3 carbon atoms.
In the general formula (b-4), Y ″ and Z ″ each independently represent a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom. Carbon number becomes like this. Preferably it is 1-10, More preferably, it is C1-C7, Most preferably, it is C1-C3.
The number of carbon atoms of the X ″ alkylene group or the number of carbon atoms of the Y ″ and Z ″ alkyl groups is preferably as small as possible because the solubility in a resist solvent is good within the above-mentioned range of carbon numbers.
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 fluorination rate of the alkylene group or alkyl group is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all hydrogen atoms are fluorine atoms. A substituted perfluoroalkylene group or a perfluoroalkyl group.

  Preferred specific examples of the component (B1) are given below.

  Among these, as the component (B1), the compounds represented by the chemical formulas (b1-01) and (b1-31) are most preferable.

(Production method of acid generator (B1))
Component (B1) includes, for example, a compound represented by the following general formula (b1-0-21) and a compound represented by the following general formula (b1-0-22), such as copper (II) benzoate It is obtained by reacting in a solvent such as chlorobenzene and iodobenzene at 80 to 130 ° C., more preferably at 100 to 120 ° C., for 0.5 to 3 hours, more preferably for 1 to 2 hours. be able to.

［式中、Ｒ^４１、ｎ_１およびＸ⁻は、上記式（ｂ１−１）中のＲ^４１、ｎ_１およびＸ⁻とそれぞれ同様である。］

^Wherein, R ^41, _{n 1} and X ^- is, ^R 41 in the formula (b1-1), _{n 1} and X ^- and are each similar. ]

［式中、Ｒ^４２、Ｒ^４３、ｎ_２およびｎ_３は、上記式（ｂ１−２）中のＲ^４２、Ｒ^４３、ｎ_２およびｎ_３とそれぞれ同様である。］

^Wherein, R ^42, R ^43, _{n 2} and _{n 3} are respectively similar to the ^{R 42, R 43,} _{n 2} and _{n 3} in the formula (b1-2). ]

  (B1) A component can be used 1 type or in mixture of 2 or more types.

  In the positive resist composition of the present invention, the content of the component (B1) in the entire component (B) is not particularly limited, and is preferably 5 to 100% by mass, more preferably 40 to 100% by mass. %, More preferably 70 to 100% by mass, and most preferably 100% by mass. By being above the lower limit of the range, a resist pattern having excellent resolution can be formed.

  In the positive resist composition of the present invention, the content of the component (B1) is preferably in the range of 0.5 to 45 parts by mass with respect to 100 parts by mass of the component (A). More preferably, it is 5 parts by mass, particularly preferably 5 to 30 parts by mass, and most preferably 10 to 25 parts by mass. By being above the lower limit of the range, a resist pattern having excellent resolution can be formed. On the other hand, when it is not more than the upper limit, the storage stability becomes better.

In the component (B), an acid generator (B2) other than the component (B1) (hereinafter referred to as the component (B2)) may be used in combination with the component (B1).
The component (B2) is not particularly limited as long as it is other than the component (B1), and those that have been proposed as acid generators for chemically amplified resists can be used.
Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

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

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

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

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

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

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

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

Specific examples of the onium salt acid generators represented by formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate; trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Sulfonate or its nonafluorobutane sulfonate, di (1-naphthyl) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; 1-phenyltetrahydrothiophenium trifluoromethane sulfonate, its heptafluoropropane sulfonate 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 the anion moiety represented by the general formula (b-3) or (b-4). Can also be used (the cation moiety is the same as (b-1) or (b-2)).

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

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

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

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

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

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

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

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

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

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

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

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

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

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), pamphlet of International Publication No. 04/074242, An oxime sulfonate-based acid generator disclosed in Examples 1 to 40) on pages 65 to 85 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

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

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

  (B2) As a component, the said acid generator may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the component (B) in the positive resist composition of the present invention is preferably 0.5 to 45 parts by mass, more preferably 1 to 40 parts by mass with respect to 100 parts by mass of the component (A). More preferably, it is 5-30 mass parts, Most preferably, it is 10-25 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 positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as the component (D)) is further added as an optional component in order to improve the resist pattern shape, the stability over time. It is preferable to contain.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. “Aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, and the like; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, a trialkylamine having 5 to 10 carbon atoms is more preferable, and tri-n-octylamine is most preferable.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
In the present invention, it is particularly preferable to use a trialkylamine having 5 to 10 carbon atoms as the component (D).
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

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

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

[(S) component]
The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any one of conventionally known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; many such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol Monohydric alcohols: compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate, monomethyl ether, monoethyl of the polyhydric alcohols or the compound having an ester bond Ether alkyl such as ether, monopropyl ether, monobutyl ether or monophenyl ether Derivatives of polyhydric alcohols such as compounds having a propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME) among these]; cyclic ethers such as dioxane, methyl lactate, Esters such as ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, Aromatic organics such as dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene A solvent etc. can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Of these, PGMEA, PGME, and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is also preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of component (S) used is not particularly limited, but it is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. -20% by mass, preferably 5-15% by mass.

The positive resist composition of the present invention can form a resist pattern with excellent resolution, and in particular, forms a high-resolution resist pattern required for forming a fine resist pattern using EB or EUV as an exposure light source. it can.
The reason is not clear, but is presumed as follows.
The positive resist composition of the present invention comprises a structural unit (a1) which is an alkali-soluble structural unit and a structural unit (a2) having an acetal type acid dissociable, dissolution inhibiting group in the side chain portion of acrylic acid. (A) It contains a component. In particular, the acetal type acid dissociable, dissolution inhibiting group of the structural unit (a2) has a low activation energy in the deprotection reaction and is easily dissociated. Therefore, the component (A) has a high dissociation ratio (deprotection rate) of the acid dissociable, dissolution inhibiting group present in the exposed area during exposure, and the alkali solubility in the exposed area is greatly increased.
Further, the positive resist composition of the present invention contains an acid generator (B1) composed of a compound represented by the above general formula (b1-1). The component (B1) is an organic solvent (resist solvent) used to dissolve various components of the positive resist composition rather than an acid generator having triphenylsulfonium (TPS) or the like in the cation part. Is excellent in solubility. Therefore, since a large amount of the component (B1) can be blended in the positive resist composition of the present invention, the density of the acid generator in the resist film can be increased and the acid generation efficiency can be further increased.
Further, the component (B1) has good dispersibility in the resist film, and is considered to be more uniformly distributed in the resist film than the conventional acid generator. For this reason, it is presumed that the acid generated from the component (B1) by exposure can diffuse more uniformly in the resist film than when a conventional acid generator is used. Further, the component (B1) is considered to have a higher dissolution inhibiting effect on an alkaline developer than a conventional acid generator.
Therefore, the positive resist composition of the present invention containing the component (A) and the acid generator (B1) has a difference in solubility (dissolution contrast) in an alkaline developer between an unexposed area and an exposed area. It is estimated that a resist pattern having excellent resolution can be formed because it is significantly larger than a conventional positive resist composition.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention includes a step of forming a resist film on a support using the positive resist composition, a step of exposing the resist film, and an alkali developing of the resist film to form a resist pattern The process of carrying out is included.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is coated on a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90, under a temperature condition of 80 to 150 ° C. The resist film is applied to the resist film by irradiating with EUV, KrF excimer laser light, etc. through a desired mask pattern, or directly irradiating (drawing) an electron beam without passing through the mask pattern. Selective exposure. Thereafter, PEB (post-exposure heating) is applied for 40 to 120 seconds, preferably 60 to 90 seconds, under a temperature condition of 80 to 150 ° C. Subsequently, this is developed using an alkaline developer, for example, a 0.1 to 10% by mass tetramethylammonium hydroxide aqueous solution, preferably rinsed with pure water and dried. In some cases, a baking process (post-bake) may be performed after the development process. In this way, a resist pattern faithful to the mask pattern can be obtained.

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

The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. The positive resist composition of the present invention is effective for lithography using KrF excimer laser, ArF excimer laser, EB or EUV, and more effective for lithography using EB or EUV. This is particularly effective for lithography.

  Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.

<Resin component (A)>
In Examples 1-2, Comparative Example 1, and Reference Example 1, resin (A) -1 synthesized by copolymerizing the following monomers (1)-(2) by a known drop polymerization method was used. .
That is, PGMEA was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring. Next, a monomer PGMEA solution charged with 2,2′-azobisisobutyronitrile (AIBN) and monomer (1) / monomer (2) = 3/1 (molar ratio) as a polymerization initiator was prepared. Using a dropping device, the solution was dropped into the flask over 6 hours at a constant speed, and then kept at 80 ° C. for 1 hour. Thereafter, the reaction solution was returned to room temperature. Subsequently, the obtained reaction solution was added dropwise to about 30 times amount of methanol with stirring to obtain a colorless precipitate. The resulting precipitate was filtered off, and the precipitate was washed in about 30 times the amount of methanol used for the monomer used for the polymerization. Then, this precipitate was separated by filtration and dissolved in THF, and then an 80% by mass hydrazine aqueous solution was added dropwise to the solution, followed by stirring at 25 ° C. for 1 hour. After completion of the reaction, the mixture was dropped into a large amount of water to obtain a precipitate. The precipitate was separated by filtration, washed, and dried under reduced pressure at 50 ° C. for about 40 hours to obtain Resin (A) -1.

The structure of Resin (A) -1 is shown below.
In addition, the mass average molecular weight (Mw) and dispersity (Mw / Mn) of the following resin (A) -1 are also shown. The mass average molecular weight (Mw) and dispersity (Mw / Mn) were determined on a polystyrene conversion basis by gel permeation chromatography (GPC).
The composition ratio was calculated by carbon NMR. In the chemical formula, the symbol attached to the lower right of the structural unit indicates the ratio (mol%) of each structural unit in the copolymer.

［ｐ１／ｑ１＝７５／２５（モル比）；Ｍｗ７０００、Ｍｗ／Ｍｎ１．７］

[P1 / q1 = 75/25 (molar ratio); Mw7000, Mw / Mn1.7]

(Examples 1-2, Comparative Example 1, Reference Example 1)
The components shown in Table 1 below were mixed and dissolved to prepare a positive resist composition.

  Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).

(B) -1: a compound represented by the following formula (b1-01).
(B) -2: a compound represented by the following formula (b1-31).
(B) -3: a compound represented by the following formula (b2-1).
(B) -4: A compound represented by the following formula (b2-2).

(D) -1: tri-n-octylamine.
(E) -1: salicylic acid.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

  Using the obtained positive resist composition, the following evaluation of resolution was performed.

<Resist pattern formation>
Each of the positive resist compositions obtained above was uniformly applied onto an 8-inch silicon substrate that had been subjected to hexamethylsilazane (HMDS) treatment (90 ° C. for 36 seconds) on the surface, and the PAB temperatures shown in Table 2 were applied. A pre-bake treatment for 90 seconds was performed to form a resist film having a thickness of 100 nm.
The resulting resist film is drawn with an electron beam drawing machine (manufactured by Hitachi, trade name: HL-800D, acceleration voltage 70 kV), and post-exposure heating (PEB) treatment for 90 seconds at the PEB temperatures shown in Table 2 The film was developed with a 2.38 mass% TMAH aqueous solution at 23 ° C. for 60 seconds, rinsed with pure water for 15 seconds, shaken and dried, and a line-and-space with a line width of 100 nm and a pitch of 200 nm (1 : 1) resist pattern (hereinafter referred to as L / S pattern).

[Evaluation of resolution]
In the resist pattern formation, the optimum exposure dose Eop (μC / cm ² ) at which an L / S pattern having a line width of 100 nm and a pitch of 200 nm is formed was determined, and the limit resolution (nm) at the Eop was determined. The results are shown in Table 2.

As is clear from the results in Table 2, the positive resist compositions of Examples 1 and 2 according to the present invention were superior in resolution compared to the positive resist compositions of Comparative Example 1 and Reference Example 1. It was confirmed that a resist pattern could be formed.
Therefore, according to the present invention, it was confirmed that a positive resist composition having excellent resolution and a resist pattern forming method using the positive resist composition can be provided.

Claims (4)

A positive resist composition comprising a resin component (A) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component (B) that generates an acid upon exposure,
The resin component (A) includes a structural unit (a1) derived from hydroxystyrene and a structural unit (a2) represented by the following general formula (a2-1) or (a2-2), and The positive resist composition, wherein the acid generator component (B) includes an acid generator (B1) composed of a compound represented by the following general formula (b1-1).

[In Formula (a2-1), R represents a hydrogen atom, a lower alkyl group having 1 to 5 carbon atoms or a halogenated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or 1 to 5 carbon atoms; Y ¹ is a lower alkyl group having 1 to 5 carbon atoms or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0 to 3. In formula (a2-2), R is as defined above; R ³ and R ⁴ are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms; R ⁵ is an alkylene group or a divalent group. An aliphatic cyclic group; Y ² is a lower alkyl group having 1 to 5 carbon atoms or a monovalent aliphatic cyclic group; and n ₂₂ is an integer of 0 to 3. ]

[In formula (b1-1), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a halogen atom, a halogenated alkyl group, an alkyl group, an acetyl group, an alkoxy group, a carboxy group or a hydroxyalkyl group; n ₁ , n ₂ and n ₃ are each independently an integer of 0 to 3. X ⁻ is an anion. ]   The positive resist composition according to claim 1, wherein the content of the acid generator (B1) is in the range of 0.5 to 45 parts by mass with respect to 100 parts by mass of the resin component (A).   The positive resist composition according to claim 1, further comprising a nitrogen-containing organic compound (D).   A step of forming a resist film on a support using the positive resist composition according to claim 1, a step of exposing the resist film, and an alkali developing of the resist film to form a resist A resist pattern forming method including a step of forming a pattern.