JP2008026725A - Positive resist composition and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition capable of forming a resist pattern excellent in resolution and a resist pattern forming method. <P>SOLUTION: The positive resist composition comprises a resin component (A) and an acid generator component (B), wherein the component (A) comprises a constitutional unit (a1) derived from hydroxystyrene and a constitutional unit (a2) having an acetal type acid-dissociable dissolution inhibiting group, and the component (B) comprises an acid generator (B1) having one anionic moiety selected from the group represented by formulae (b-3), (b-4) and (b-5). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

In photolithography technology, for example, a resist film made of a resist composition is formed on a substrate, and the resist film is irradiated with radiation such as light or an electron beam through a photomask on which a predetermined pattern is formed. A step of forming a resist pattern having a predetermined shape on the resist film is performed by performing selective exposure and developing. 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, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a means for miniaturization, the wavelength of exposure light is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now KrF is used. Excimer laser (248 nm) has been introduced, and ArF excimer laser (193 nm) has begun to be introduced. In addition, studies have been conducted on shorter wavelength F ₂ excimer lasers (157 nm), EUV (extreme ultraviolet rays), electron beams, X-rays, and the like.

In order to reproduce a pattern with fine dimensions, a resist material having high resolution is required. As such a resist material, a chemically amplified resist composition containing a base resin and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains a resin component whose alkali solubility is increased by the action of an acid and an acid generator component that generates an acid upon exposure. When an acid is generated from the generator, the exposed portion becomes alkali-soluble.
The resin component of the chemically amplified positive resist composition is mainly composed of a resin in which the hydroxyl group of a polyhydroxystyrene (PHS) resin is protected with an acid dissociable, dissolution inhibiting group, or a structural unit derived from (meth) acrylic acid. A resin in which a carboxy group of a resin (acrylic resin) in a chain is protected with an acid dissociable, dissolution inhibiting group is generally used. Examples of acid dissociable, dissolution inhibiting groups include so-called acetal groups such as chain ether groups typified by 1-ethoxyethyl groups and cyclic ether groups typified by tetrahydropyranyl groups; third groups typified by tert-butyl groups. A tertiary alkyl group; a tertiary alkoxycarbonyl group typified by a tert-butoxycarbonyl group is used (for example, see Patent Document 1).
Here, “(meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. “(Meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position. “(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.

On the other hand, a wide variety of acid generators for chemically amplified positive resist compositions have been proposed. For example, onium salt acid generators such as iodonium salts and sulfonium salts, and oxime sulfonate acid generators. A diazomethane acid generator, a nitrobenzyl sulfonate acid generator, an imino sulfonate acid generator, a disulfone acid generator, and the like are known. Currently, the acid generator has a cation part made of triphenylsulfonium (TPS) and an anion part made of a fluorinated alkyl sulfonate ion such as nonafluorobutane sulfonate, among others, because of its high acid generation ability. Onium salt acid generators are the most common (see, for example, Patent Document 2).
JP 2002-341538 A JP 2003-241385 A

In recent years, the miniaturization of resist patterns has further progressed, and further improvement in resolution has been demanded for resist patterns formed from conventional chemically amplified positive resist compositions.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a positive resist composition and a resist pattern forming method capable of forming a resist pattern having excellent resolution.

As a result of intensive studies, the 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 anion moiety. The present invention was completed.
That is, the first aspect of the present invention is a positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) that generates an acid upon exposure. The resin component (A) comprises 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) is an acid having at least one anion moiety selected from the group represented by the following general formulas (b-3), (b-4) and (b-5) A positive resist composition comprising a generator (B1).

［式（ａ２−１）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；Ｒ^１および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であり；Ｙ^１は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 halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group; Y ¹ Is a lower alkyl group or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0-3. 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; R ⁵ is an alkylene group or a divalent aliphatic cyclic group. There; ^{Y 2} is a lower alkyl group or a monovalent aliphatic cyclic _{group; n 22} is an integer of 0 to 3. ]

［式（ｂ−３）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す。式（ｂ−４）中、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。式（ｂ−５）中、Ｕ”、Ｖ”、Ｗ”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。］

[In formula (b-3), X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom. In formula (b-4), Y ″ and Z ″ each represent And independently represents an alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom. In formula (b-5), U ″, V ″, and W ″ each independently represent at least one hydrogen atom. Represents an alkyl group having 1 to 10 carbon atoms substituted with a fluorine atom. ]

  According to a second aspect of the present invention, a resist film is formed on a substrate using the positive resist composition of the first aspect, the resist film is exposed, and the resist film is developed to form a resist. A resist pattern forming method including a step of forming a pattern.

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

  According to the present invention, a positive resist composition and a resist pattern forming method capable of forming a resist pattern with excellent resolution can be provided.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter referred to as “component (A)”), and an acid generator component (B) that generates an acid upon exposure. (Hereinafter referred to as the component (B)).
Such a positive resist composition is insoluble in alkali before exposure, and when an acid is generated from the component (B) by exposure, the acid acts on the component (A) to increase its alkali solubility.
Therefore, in the formation of the resist pattern, when the resist film obtained by using the positive resist composition is selectively exposed, the exposed portion turns to alkali-soluble, while the unexposed portion remains alkali-insoluble and does not change. A resist pattern can be formed by performing alkali development.

<(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. When the component (A) has the structural unit (a1) and the structural unit (a2) described later, the effects of the present invention are improved. Moreover, when the component (A) has 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.
As used herein, “hydroxystyrene” refers to hydroxystyrene, and those obtained by replacing the hydrogen atom at the α-position of hydroxystyrene with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group, and derivatives thereof. Include concepts.
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 (a-1) can be illustrated.

［式（ａ−１）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；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 (a-1), R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ⁶ is a lower alkyl group; p is an integer of 1 to 3; It is an integer of 0-2. ]

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

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

q is an integer of 0-2. Among these, q is preferably 0 or 1, and is preferably 0 industrially.
Examples of the lower alkyl group for R ⁶ include the same lower alkyl groups as those described above for R.
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.

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

[Structural unit (a2)]
The structural unit (a2) is a structural unit represented by the general formula (a2-1) or (a2-2). When the component (A) has the structural unit (a2) and the structural unit (a1), the effects of the present invention are improved.
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.
“Dissolution-inhibiting group” means a group that has an alkali dissolution inhibiting property that makes the entire component (A) insoluble in alkali before dissociation and changes the entire component (A) to alkali-soluble after dissociation. .
Therefore, the component (A) containing the structural unit (a2) is insoluble in alkali before exposure, and when an acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group is dissociated, thereby (A) The alkali solubility of the whole component increases and changes from alkali insoluble to alkali soluble. Therefore, when a resist film obtained by using a positive resist composition is selectively exposed in the formation of a resist pattern, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, alkali development can be performed.

In general formula (a2-1), R represents a hydrogen atom, a halogen atom, a lower alkyl group, or a halogenated lower alkyl group. Examples of R include the same as R in the general formula (a-1).
R ¹ and R ² are each independently a hydrogen atom or a lower alkyl group. The lower alkyl group for R ¹ and R ^{2 is} an alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert- Examples thereof include linear or branched alkyl groups such as a butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Among these, a methyl group and an ethyl group are preferable in terms of industrial availability.
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 or a monovalent aliphatic cyclic group.
Examples of the lower alkyl group for Y ¹ include the same lower alkyl groups as those described above for R.
As the aliphatic cyclic group for Y ¹ , it can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups which have been conventionally proposed in resist resins for ArF excimer lasers and the like. .
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 (4) to (15). 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, and Y ² represents a lower alkyl group or a monovalent aliphatic cyclic group. N ₂₂ is an integer of 0-3.
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.
The alkylene group for R ⁵ is preferably an alkylene group having 1 to 4 carbon atoms.
The aliphatic cyclic group for R ⁵ 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 obtained by removing two or more hydrogen atoms from a polycycloalkane such as tricycloalkane or tetracycloalkane. Specifically, a group obtained by removing two or more hydrogen atoms from a monocycloalkane such as cyclopentane or cyclohexane, or two or more polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Examples include a group excluding a hydrogen atom.
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 (a1-243). Can be mentioned.
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 (a1-4-30). Can be mentioned.

  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), The structural unit represented by the formula (a1-2-16) is particularly preferable because of excellent effects of the present invention.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
In the component (A), the proportion of the structural unit (a2) 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 the structural units constituting the component (A). More preferred is mol%. When it is at least the lower limit of the range, a pattern can be obtained when it is a positive resist composition, and when it is at most the upper limit, the balance with other structural units is good.

[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 a developer can be adjusted. In addition, dry etching resistance is improved.
Here, the term “styrene” includes styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group. “Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.
As a suitable thing of a structural unit (a4), the structural unit represented by the following general formula (a4-1) can be illustrated.

［式中、Ｒは前記と同じであり；Ｒ^７は低級アルキル基であり；ｒは０〜３の整数である。］

[Wherein, R is as defined above; R ⁷ is a lower alkyl group; and r is an integer of 0 to 3. ]

In general formula (a4-1), R and R ⁷ are the same as R and R ^{6 in} formula (a-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, and when r is 2 or 3, any substitution position may be selected. Can be combined.

As the structural unit (a4), one type may be used alone, or two or more types may be used in combination.
When the 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 other structural units (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 structural units (a1), (a2), and (a4) described above. For the ArF excimer laser and the KrF excimer laser ( A number of hitherto known materials can be used that are preferably used for resist resins such as ArF excimer laser).

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 the resin component include a copolymer having structural units (a1) and (a2), a copolymer 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.
As this (A) component, what contains the copolymer which has 2 types of structural units shown by the following general formula (A-11) especially is preferable.

［式中、Ｒは前記と同じであり；ｎ_１５は０または１である。］

[Wherein R is as defined above; n ₁₅ is 0 or 1; ]

In formula (A-11), R is preferably a hydrogen atom or a methyl group.
n ₁₅ is particularly preferably 0.

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, but is preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 5000. 20000 is 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 when it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) is not particularly limited, but 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.

<(B) component>
In the present invention, the component (B) is an acid generator having at least one anion moiety selected from the group represented by the general formulas (b-3), (b-4) and (b-5) ( B1) (hereinafter referred to as component (B1)).
By including the component (B1), the resolution of the formed resist pattern is improved.

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 has 2 to 6 carbon atoms. , Preferably 3 to 5 carbon atoms, most preferably 3 carbon atoms.
In the general formula (b-4), 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 carbon of the alkyl group The number is 1 to 10, preferably 1 to 7 carbon atoms, and more preferably 1 to 4 carbon atoms.
In the general formula (b-5), U ″, V ″, and W ″ each independently represent a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom. The group has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and 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 ″, Z ″, U ″, V ″, W ″ is within the above carbon number range, and the solubility in the resist solvent is good. For this reason, the smaller the better.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″, Z ″, U ″, V ″, W ″, the strength of the acid increases as the number of hydrogen atoms substituted by fluorine atoms increases. This is preferable because transparency to high energy light of 200 nm or less and an electron beam is improved. The proportion 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 hydrogen atoms are substituted with fluorine atoms. A perfluoroalkylene group or a perfluoroalkyl group.

  The cation part of the component (B1) is not particularly limited, and examples thereof include those similar to the cation part of acid generators proposed so far, such as the cation part of an onium salt acid generator. As such a cation moiety, for example, the same cation moiety as exemplified in the acid generator (B2) described later is preferably exemplified, and in particular, it is represented by the following general formula (b′-1) or (b′-2). Particularly preferred is a cation moiety.

［式（ｂ’−１）中、Ｒ^１”〜Ｒ^３” はそれぞれ独立にアリール基またはアルキル基を表し、少なくとも１つはアリール基を表す。式（ｂ’−２）中、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、少なくとも１つはアリール基を表す。］

[In Formula (b′-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group, and at least one represents an aryl group. In formula (b′-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group, and at least one represents an aryl group. ]

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

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

  Specific examples of the cation moiety represented by the formula (b′-1) or (b′-2) include diphenyliodonium ion, bis (4-tert-butylphenyl) iodonium ion, triphenylsulfonium ion, tri (4 -Methylphenyl) sulfonium ion, dimethyl (4-hydroxynaphthyl) sulfonium ion, monophenyldimethylsulfonium ion, diphenylmonomethylsulfonium ion, (4-methylphenyl) diphenylsulfonium ion, (4-methoxyphenyl) diphenylsulfonium ion, tri ( 4-tert-butyl) phenylsulfonium ion, diphenyl (1- (4-methoxy) naphthyl) sulfonium ion, diphenylmononaphthylsulfonium ion, di (1-naphthyl) monophenyls Honiumuion, and the like.

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

In the present invention, the component (B1) is at least one acid selected from the group represented by the chemical formulas (b-3-1), (b-4-1) and (b-5-1). An agent is particularly preferred.
(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 preferably 40% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. It is particularly preferable that it may be 100% by mass. Most preferably, it is 100 mass%. By being above the lower limit of the range, the resolution of the resist pattern is improved.
Moreover, in the positive resist composition of this invention, it is preferable that content of (B1) component is 1-40 mass parts with respect to 100 mass parts of said (A) component, and is 5-25 mass parts. Particularly preferred is 10 to 20 parts by mass. By being above the lower limit of the range, the resolution of the resist pattern is improved. On the other hand, when it is not more than the upper limit value, 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)) is used in combination with the component (B1) as long as the effects of the present invention are not impaired. Also good.
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.
As such component (B2), onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethanes There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like.

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

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

In General Formula (b-0), R ⁵¹ represents a linear, branched, or cyclic alkyl group, or a linear, branched, or cyclic fluorinated alkyl group.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The fluorination rate of the fluorinated alkyl group (ratio of the number of substituted fluorine atoms to the total number of hydrogen atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly Those in which all hydrogen atoms are substituted with fluorine atoms are preferred because the strength of the acid is increased.
R ⁵¹ is most preferably a linear alkyl group or a fluorinated alkyl group.

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

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

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

  In addition, as another onium salt-based acid generator represented by the general formula (b-0), for example, a compound represented by the following general formula (b-1) or (b-2) is also preferable. 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；Ｒ^４”は直鎖、分岐または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

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

In formula (b-1), R ¹ ″ to R ³ ″ are the same as R ¹ ″ to R ³ ″ exemplified in the above formula (b′-1).
In the formula (b-2), R ⁵ ″ to R ⁶ ″ are the same as R ⁵ ″ to R ⁶ ″ exemplified in the above formula (b′-2).

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

  Specific examples of the onium salt acid generators represented by the formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same Nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, its heptaful Lopropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenylmonomethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate , Trifluoromethanesulfonate of tri (4-tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of diphenyl (1- (4-methoxy) naphthyl) sulfonium, its heptafluoropropane Sulfonate or its nonafluorobutane sulfonate, di (1-naphthyl) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate. In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

  In 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 acid generators are frequently used for chemically amplified resist compositions, and can be arbitrarily selected and used.

［式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。］

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

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

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

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

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

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

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

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

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

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

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

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), 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.

Among these, it is preferable to use an onium salt having a fluorinated alkyl sulfonate ion in the anion portion as the component (B2).
As the component (B2), one type of acid generator may be used alone, or two or more types may be used in combination.

  In the positive resist composition of the present invention, the content of the entire component (B) is preferably 0.5 to 45 parts by mass, more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the component (A). It is said. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(D) component>
The positive resist composition of the present invention further contains a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component in order to improve the resist pattern shape, the stability over time, and the like. It is preferable to do.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. “Aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include an amine (alkyl amine or alkyl alcohol amine) or a cyclic amine in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine , 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, alkylamine is preferred as component (D), and tri-n-octylamine is particularly preferred.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

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

The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution, 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-amyl ketone, methyl isoamyl ketone, 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol A compound having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, or propylene glycol monoacetate, monomethyl ether, monoethyl ether of the polyhydric alcohol or the compound having an ester bond, Ether bonds such as monoalkyl ethers such as monopropyl ether and monobutyl ether or monophenyl ethers Derivatives of polyhydric alcohols such as compounds having [Propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred among these]; Cyclic ethers such as dioxane, methyl lactate, lactic acid Esters such as ethyl (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, di Aromatic organic solvents such as benzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene Etc.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Of these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
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.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention includes a step of forming a resist film on a substrate using the positive resist composition of the present invention, a step of exposing the resist film, and developing the resist film to form a resist pattern. It is a method including the process of forming.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is applied onto a substrate such as a silicon wafer using a spinner or the like, and pre-baking (post-apply baking (PAB)) is preferably performed for 40 to 120 seconds under a temperature condition of 80 to 150 ° C. Is applied for 60 to 90 seconds, and this is irradiated with EUV, KrF excimer laser light, etc. through a desired mask pattern or directly with an electron beam (drawing) without passing through the mask pattern. The resist film is selectively exposed. Then, 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 alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. In this way, a resist pattern can be obtained.
An organic or inorganic antireflection film can be provided between the substrate and the coating layer of the resist composition.
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 Or the like. The positive resist composition according to the present invention is effective for lithography using a KrF excimer laser, EUV or EB, and particularly effective for EUV.

According to the positive resist composition and the resist pattern forming method of the present invention, a resist pattern having excellent resolution can be formed. The reason is not clear, but it is thought 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.
In addition, the positive resist composition of the present invention comprises a component (B1) having a sterically bulky and bulky anion moiety (the general formula (b-3), (b-4) or (b-5)). An acid generator having an anion moiety represented by: Thereby, compared with the conventional anion part, such as nonafluorobutane sulfonate, the density of the acid generator in the resist film can be increased, and since the component (B1) has a short acid diffusion distance, The generation efficiency is considered to be suppressed.
Therefore, according to the positive resist composition of the present invention containing the component (A) and the component (B1), the difference in alkali solubility (dissolution contrast) between the unexposed portion and the exposed portion is the conventional positive type. It is presumed that the resist pattern to be formed is excellent in resolution by being significantly larger than the case where the resist composition is used.

Furthermore, according to the present invention, a resist pattern having a good shape can be obtained.
For example, a resist pattern with less roughness on the pattern surface can be formed. Roughness may adversely affect the formation of fine semiconductor elements and the like. For example, the roughness of the resist pattern side wall surface, that is, line edge roughness (LER) is the distortion around the hole in the hole pattern or the line in the line-and-space pattern. This may cause variations in width. The roughness problem becomes more serious as the pattern dimension is smaller. For example, in lithography using an electron beam or EUV, the target is to form a fine pattern of several tens of nanometers. Therefore, improvement of roughness is very important.
In the present invention, a resist pattern with little film loss can be formed. The film reduction is the amount of change in the film thickness of the resist film before and after development. The smaller the film reduction, the more useful the etching process using the resist pattern as a mask.
These effects are considered to be due to an improvement in dissolution contrast, as described above.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
In Examples 1 to 3 and Comparative Example 1 below, resin (A) -1 synthesized by copolymerizing the following monomers (1) to (2) by a known dropping 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. Next, the obtained reaction solution was dropped into about 30 times amount of methanol with stirring to obtain a colorless precipitate. The resulting precipitate was filtered off, and the precipitate was washed in about 30 times the amount of methanol used for the monomer used for the polymerization. Then, this precipitate was filtered off and dissolved in THF, and then an 80% by mass hydrazine aqueous solution was added dropwise to the solution, followed by stirring at 25 ° C. for 1 hour. After completion of the reaction, the mixture was dropped into a large amount of water to obtain a precipitate. The precipitate was separated by filtration, washed, and dried under reduced pressure at 50 ° C. for about 40 hours to obtain Resin (A) -1.

  The structure of Resin (A) -1 is shown below.

［ｐ１／ｑ１＝７５／２５（モル比）；Ｍｗ７０００；Ｍｗ／Ｍｎ１．７］

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

Examples 1 to 3, Comparative Example 1
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 1 has the following meaning, and the numerical value in [] is the blending amount (part by mass).
(B) -1: a compound represented by the following formula (b-3-1).
(B) -2: a compound represented by the following formula (b-5-1).
(B) -3: a compound represented by the following formula (b-4-1).
(B) -4: A compound represented by the following formula (B) -4.

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

Each of the positive resist compositions obtained above is uniformly applied onto an 8-inch silicon substrate having a hexamethylsilazane (HMDS) treatment on the surface, and a pre-bake treatment is performed for 90 seconds at the PAB temperature shown in Table 2. Thus, a resist film having a thickness of 100 nm was formed.
The resulting resist film is drawn with an electron beam drawing machine (manufactured by Hitachi, trade name: HL-800D, acceleration voltage 70 kV), subjected to a post-exposure heat treatment for 90 seconds at the PEB temperature shown in Table 2, A development process is performed for 60 seconds with a 2.38 mass% TMAH aqueous solution at 23 ° C., rinsed with pure water for 15 seconds, and shaken and dried to form a line-and-space (1: 1) resist pattern (hereinafter referred to as L / S pattern).
At this time, an 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 was formed was obtained, and a limit resolution (nm) at the Eop was obtained. The results are shown in Table 2.

As is clear from the results in Table 2, the positive resist compositions of Examples 1 to 3 according to the present invention form a resist pattern with excellent resolution as compared with the positive resist composition of Comparative Example 1. I was able to confirm that it was possible.

Claims (4)

A positive resist composition comprising a resin component (A) whose alkali solubility 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 acid generator component (B) is an acid generator (B1) having at least one anion moiety selected from the group represented by the following general formulas (b-3), (b-4) and (b-5) And a positive resist composition.

[In formula (a2-1), R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group; Y ¹ Is a lower alkyl group or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0-3. 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; R ⁵ is an alkylene group or a divalent aliphatic cyclic group. There; ^{Y 2} is a lower alkyl group or a monovalent aliphatic cyclic _{group; n 22} is an integer of 0 to 3. ]

[In formula (b-3), X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom. In formula (b-4), Y ″ and Z ″ each represent And independently represents an alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom. In formula (b-5), U ″, V ″, and W ″ each independently represent at least one hydrogen atom. Represents an alkyl group having 1 to 10 carbon atoms substituted with a fluorine atom. ]   The positive resist composition according to claim 1, wherein the content of the acid generator (B1) is in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the resin component (A).   The positive resist composition according to claim 1 or 2, further comprising a nitrogen-containing organic compound (D). A step of forming a resist film on a substrate using the positive resist composition according to claim 1, a step of exposing the resist film, and developing the resist film to form a resist pattern A resist pattern forming method including a forming step.