JP4574507B2 - Positive resist composition and resist pattern forming method - Google Patents

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 been rapidly progressing 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 at present, mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. In addition, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.

Resist materials are required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions. As a resist material satisfying such requirements, a chemically amplified resist containing a base resin whose alkali solubility is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains, as a base resin, a resin whose alkali solubility is increased by the action of an acid and an acid generator. When a resist pattern is formed, an acid is generated from the acid generator by exposure. The exposed part becomes alkali-soluble.
Up to now, as a base resin for chemically amplified resist, polyhydroxystyrene (PHS) having high transparency with respect to KrF excimer laser (248 nm) and a resin whose hydroxyl group is protected with an acid dissociable, dissolution inhibiting group (PHS resin) Has been used. However, since the PHS resin has an aromatic ring such as a benzene ring, the transparency to light having a wavelength shorter than 248 nm, for example, 193 nm, is not sufficient. For this reason, a chemically amplified resist having a PHS resin as a base resin component has drawbacks such as low resolution in a process using 193 nm light, for example. Therefore, as a resist base resin currently used in ArF excimer laser lithography and the like, since it has excellent transparency near 193 nm, a resin (acrylic resin) having a structural unit derived from (meth) acrylic ester is used. System resin) is mainly used (see, for example, Patent Document 1).
A wide variety of acid generators used in chemically amplified resists have been proposed. For example, onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, and diazomethane acid generators. Agents, iminosulfonate acid generators, disulfone acid generators and the like are known. Currently, onium salt acid generators are mainly used as acid generators because of their high acid generating ability. Among them, fluorinated alkyls such as triphenylsulfonium nonafluorobutanesulfonate (TPS-PFBS) are used. An onium salt acid generator having a sulfonate ion as an anion (acid) is the most common (see, for example, Patent Document 2).
Japanese Patent No. 2881969 JP 2003-241385 A

In recent years, as the resist pattern is further miniaturized, it is required to improve various lithography characteristics as well as high resolution. In particular, in order to improve the process margin and the like during pattern formation, improvement in the depth of focus (DOF) and exposure margin (EL margin) is required. DOF is a range of depth of focus in which a resist pattern can be formed with a dimension within which a deviation from a target dimension is within a predetermined range when exposure is performed with the same exposure amount while shifting the exposure focus up and down, that is, a resist faithful to the mask pattern. This is the range where the pattern can be obtained, and the larger the DOF, the better. The EL margin is an exposure amount range in which a resist pattern can be formed with a dimension within which the deviation from the target dimension is within a predetermined range when exposure is performed with different exposure amounts, that is, an exposure that provides a resist pattern faithful to the mask pattern. It is a range of quantity, and the larger the EL margin, the better.
However, in the conventional chemically amplified resist, when the DOF is improved, the EL margin tends to be small, and it is difficult to achieve both the improvement of the DOF and the EL margin.
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 having a large DOF and an excellent EL margin.

As a result of intensive studies, the present inventors have found that the above problem can be solved by using an oxime sulfonate acid generator having a specific structure and an onium salt acid generator in combination as an acid generator, The present invention has been 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) which generates an acid upon exposure. And
The resin component (A) includes a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, represented by the following general formula (a1-1-02):
The acid generator component (B) has an oxime sulfonate-based acid generator represented by the following general formula (B1) and (B1), a cation moiety represented by the following general formula (b'-1) A positive resist composition comprising an onium salt acid generator (B2).

［式中、Ｒは水素原子、ハロゲン原子、炭素数１〜５のアルキル基または炭素数１〜５のハロゲン化アルキル基を示し、Ｒ ^１２ は炭素数１〜５のアルキル基を示し、ｈは１〜３の整数を表す。］

［式（Ｂ−１）中、Ｒ^３３は、ハロゲン化アルキル基であり、Ｒ^３４はアリール基であり、Ｒ^３５はハロゲン化アルキル基である。］

［式中、Ｒ ^１ ”〜Ｒ ^３ ”のうちの２つはナフチル基を表し、１つはフェニル基を表す。］

[Wherein, R represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms , R ¹² represents an alkyl group having 1 to 5 carbon atoms, and h represents Represents an integer of 1 to 3; ]

[In Formula (B-1), R ³³ is a halogenated alkyl group, R ³⁴ is an aryl group, and R ³⁵ is a halogenated alkyl group. ]

[Wherein, two of R ¹ ″ to R ³ ″ represent a naphthyl group, and one represents a phenyl group. ]

  The second aspect of the present invention includes a step of forming a resist film on a substrate using the positive resist composition of the first aspect, a step of exposing the resist film, and developing the resist film. A resist pattern forming method including a step of forming a resist pattern.

In the present specification and claims, unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
The alkyl group may have a substituent. Examples of the substituent in the alkyl group include a halogen atom such as a fluorine atom, and a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms. Here, the alkyl group having a substituent means that part or all of the hydrogen atoms of the alkyl group are substituted with the substituent.
The “halogenated alkyl group” is an alkyl group having a halogen atom as a substituent, and unless otherwise specified, includes a partially or fully halogenated linear, branched or cyclic alkyl group. . A partially halogenated alkyl group means an alkyl group in which some of the hydrogen atoms are replaced with halogen atoms, and a fully halogenated alkyl group means that all of the hydrogen atoms are replaced with halogen atoms. Means a substituted alkyl group.
“Aryl group” means a group obtained by removing one hydrogen atom from an aromatic ring in an aromatic compound unless otherwise specified, and an aromatic compound has one or more aromatic rings (benzene ring, naphthalene ring, etc.). The aromatic hydrocarbon has a concept and a hetero compound in which a part of carbon atoms constituting the aromatic compound is substituted with a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. Examples of the hetero compound include a heterocyclic compound in which a part of carbon atoms constituting the aromatic ring of the aromatic hydrocarbon is substituted with a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom.
The aryl group may have a substituent. Examples of the substituent for the aryl group include a halogen atom such as a fluorine atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and an aryl group. Here, having a substituent means that part or all of the hydrogen atoms of the aryl group are substituted with a substituent.
“Exposure” is a concept including general irradiation of radiation.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition and a resist pattern forming method having a large DOF and an excellent EL margin.

≪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 component (B)).
In the positive resist composition of the present invention, the component (A) is alkali-insoluble before exposure, and when an acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group dissociates. As a result, the alkali solubility of the entire component (A) 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.

<(A) component>
The component (A) is not particularly limited, and those conventionally proposed as base resins for positive chemically amplified resists can be used, such as polyhydroxystyrene resins and acrylate esters. Examples thereof include resins.

The component (A) preferably has a structural unit derived from an acrylate ester. A resin having such a structural unit is particularly highly transparent to an ArF excimer laser, and can be suitably used in lithography using an ArF excimer laser.
In the component (A), the proportion of the structural unit derived from the acrylate ester is preferably 20 mol% or more, and 50 mol% or more with respect to the total of all the structural units constituting the component (A). More preferably, 80 mol% or more is more preferable, and 100 mol% may be sufficient.

Here, in the present specification and claims, the “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer).
The “structural unit derived from an acrylate ester” means a structural unit constituted by cleavage of an ethylenic double bond of an acrylate ester.
“Acrylic acid esters” include those in which a hydrogen atom is bonded to the carbon atom at the α-position, and those in which a substituent (atom or group other than a hydrogen atom) is bonded to the carbon atom in the α-position. Include concepts. Examples of the substituent include a halogen atom, a lower alkyl group, and a halogenated lower alkyl group.
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.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorine atom. A lower alkyl group is more preferable, and a hydrogen atom or a methyl group is most preferable in terms of industrial availability.
The α-position (α-position carbon atom) of a structural unit derived from an acrylate ester is a carbon atom to which a carbonyl group is bonded unless otherwise specified.

Furthermore, the component (A) preferably has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
In addition to the structural unit (a1), it is preferable to have a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Furthermore, in addition to the structural unit (a1) or in addition to the structural unit (a1) and the structural unit (a2), the structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group ).

・ Structural unit (a1)
The structural unit (a1) is a structural unit derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire copolymer (A1) insoluble in alkali before dissociation, and the entire copolymer (A1) is alkalinized after dissociation. As long as it is changed to be soluble, those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid, or a group that forms a cyclic or chain alkoxyalkyl ester is widely known. . The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

  As the structural unit (a1), one type selected from the group consisting of structural units represented by general formula (a1-0-1) shown below and structural units represented by general formula (a1-0-2) shown below. It is preferable to use the above.

（式中、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を示し；Ｘ^１は酸解離性溶解抑制基を示す。）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; X ¹ represents an acid dissociable, dissolution inhibiting group.)

（式中、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を示し；Ｘ^２は酸解離性溶解抑制基を示し；Ｙ^２はアルキレン基または脂肪族環式基を示す。）

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

In the general formula (a1-0-1), the halogen atom, lower alkyl group or halogenated lower alkyl group of R is a halogen atom, lower alkyl group or halogenated lower group which may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include an alkoxyalkyl group, a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, and the like. Acid dissociable, dissolution inhibiting groups are preferred. Examples of the tertiary alkyl ester type acid dissociable, dissolution inhibiting group include an aliphatic branched acid dissociable, dissolution inhibiting group and an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group is preferred.
Specific examples of such aliphatic cyclic groups include, for example, monocycloalkanes, bicycloalkanes, trialkyls which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane or tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Specific examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a tert-butyl group and a tert-amyl group.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group, specifically 2-methyl Examples include a 2-adamantyl group and a 2-ethyl-2-adamantyl group. Alternatively, as a structural unit represented by the following general formula, a group having an aliphatic cyclic group such as an adamantyl group and a branched alkylene group having a tertiary carbon atom bonded thereto can be given.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６はアルキル基（直鎖、分岐鎖状のいずれでもよく、好ましくは炭素数１〜５である）を示す。］

[Wherein, R is the same as described above, and R ¹⁵ and R ¹⁶ represent an alkyl group (which may be linear or branched, and preferably has 1 to 5 carbon atoms). ]

  Further, the alkoxyalkyl group is preferably a group represented by the following general formula.

（式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐状または環状のアルキル基である。または、Ｒ^１７とＲ^１９の末端が結合して環を形成していてもよい。）

(Wherein R ¹⁷ and R ¹⁸ are each independently a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ is a linear, branched or cyclic alkyl group, or R ^17. And the end of R ¹⁹ may be bonded to form a ring.)

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

In general formula (a1-0-2), R is the same as defined above. X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group.
When Y ² is a divalent aliphatic cyclic group, it is the same as the description of the “aliphatic cyclic group” in the structural unit (a1) except that a group in which two or more hydrogen atoms are removed is used. Can be used.

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

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

[In the above formula, X ′ represents a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, Y represents a lower alkyl group having 1 to 5 carbon atoms, or an aliphatic cyclic group; M represents 0 or 1; R is the same as defined above; R ¹ ′ and R ² ′ each independently represent a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms. ]

In the R ¹ ′ and R ² ′, at least one is preferably a hydrogen atom, and more preferably both are hydrogen atoms. n is preferably 0 or 1.

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

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

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
Among these, the structural unit represented by General Formula (a1-1) is preferable, and specifically, (a1-1-1) to (a1-1-6) or (a1-1-35) to (a1- It is more preferable to use at least one selected from structural units represented by 1-41).
Furthermore, as the structural unit (a1), in particular, those represented by the following general formula (a1-1-01) including the structural units of the formulas (a1-1-1) to (a1-1-4) And the following general formula (a1-1-02) including the structural units of the formulas (a1-1-36), (a1-1-38), (a1-1-39) and (a1-1-41) preferable.

（式中、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を示し、Ｒ^１１は低級アルキル基を示す。）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹¹ represents a lower alkyl group.)

（式中、Ｒは水素原子、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を示し、Ｒ^１２は低級アルキル基を示す。ｈは１〜３の整数を表す）

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ¹² is .h represents an integer of 1 to 3 represents a lower alkyl group)

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

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

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

・ Structural unit (a2)
The structural unit (a2) is a structural unit derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
The lactone cyclic group in the structural unit (a2) increases the adhesion of the resist film to the substrate and the hydrophilicity with the developer when the component (A) is used for forming a resist film. It is effective.

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

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

［式中、Ｒは水素原子、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’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数である。］

[Wherein, R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is 0 or It is an integer of 1. ]

R in the general formulas (a2-1) to (a2-5) is the same as R in the structural unit (a1).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Among these, it is preferable to use at least one selected from structural units represented by general formulas (a2-1) to (a2-3). Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the component (A) is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, based on the total of all structural units constituting the component (A). 50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) is sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

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

  The structural unit (a3) is derived from a hydroxyethyl ester of acrylic acid when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms. When the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), (a3-3) The structural unit represented by is mentioned as a preferable thing.

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

(Wherein R is the same as above, j is an integer of 1 to 3, k is an integer of 1 to 3, t 'is an integer of 1 to 3, and l is an integer of 1 to 5) And s is an integer of 1 to 3.)

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

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

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

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

・ Structural unit (a4)
The component (A) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a1) to (a3) described above. For ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser) A number of conventionally known resins can be used for resist resins such as
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may be substituted with a linear or branched alkyl group having 1 to 5 carbon atoms.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

(In the formula, R is as defined above.)

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

In the present invention, the component (A) is preferably a copolymer having the structural units (a1), (a2) and (a3) (hereinafter referred to as copolymer (A1)).
Examples of the copolymer (A1) include a copolymer composed of the structural units (a1), (a2) and (a3), and the structural units (a1), (a2), (a3) and (a4). The copolymer etc. which become can be illustrated.
As the copolymer (A1), those containing three kinds of structural units represented by the following general formula (A1-11) are particularly preferable.

［式中、Ｒは前記と同じであり、Ｒ^１０は低級アルキル基である。］

[Wherein, R is the same as defined above, and R ¹⁰ represents a lower alkyl group. ]

In formula (A1-11), the lower alkyl group for R ^{10 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group.

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 into which a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom is introduced has reduced development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw) of the component (A) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and most preferably 5000 to 20000. preferable. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape that are larger than the lower limit of this range are good.
Further, the dispersity (Mw / Mn) 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>
The component (B) includes an oxime sulfonate acid generator (B1) represented by the general formula (B-1) (hereinafter sometimes referred to as an acid generator (B1)) and an onium salt acid generator. (B2) (hereinafter sometimes referred to as an acid generator (B2)).

  Here, in this specification, the “oxime sulfonate acid generator” is a compound having at least one group represented by the following general formula, and has a property of generating an acid upon irradiation with radiation. is there.

（式中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

(In the formula, 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.
The organic group for R ³¹ is generally a linear, branched, or cyclic alkyl group or aryl group. These alkyl groups and aryl groups may have a substituent.
^Examples of the organic group for R ³² include linear, branched, or cyclic alkyl groups, aryl groups, and cyano groups. 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.

[Acid generator (B1)]
The acid generator (B1) is a compound represented by the general formula (B-1).
In the general formula (B-1), R ³³ is a halogenated alkyl group.
Halogenated alkyl group for R ³³ preferably has a carbon number of 1 to 20, more preferably 1 to 10 carbon atoms, 1 to 8 carbon atoms are more preferred, 1 to 6 carbon atoms and most preferable.
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, and the fluorinated alkyl group preferably has 50% or more of hydrogen atoms in the alkyl group, more preferably 70% or more, More preferably, 90% or more is fluorinated.
The fluorinated alkyl group is particularly preferably a partially fluorinated alkyl group. Among them, an alkyl group in which all but one of the hydrogen atoms bonded to the carbon atom at the terminal of the alkyl group are all fluorinated is used. preferable.

The aryl group R ^34, a phenyl group, biphenyl (biphenyl) group, fluorenyl (fluorenyl) group, a naphthyl group, Antoraseru (anthracyl) group, or a phenanthryl group, one hydrogen atom from an aromatic ring of an aromatic hydrocarbon Excluded groups and heteroaryl groups in which some of the carbon atoms constituting these groups are substituted with heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms and the like.
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.
The aryl group for R ³⁴ may have a substituent. Examples of the substituent include a halogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkoxy group, and an aryl group. As the halogen atom, a fluorine atom is preferable. The alkyl group or halogenated alkyl group 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 aryl group include a hydrocarbon group such as a phenyl group and a benzyl group, and a heteroaryl group in which a part of carbon atoms constituting the hydrocarbon group is substituted with a heteroatom such as an oxygen atom or a sulfur atom. . Examples of the aryl group having a heteroaryl group as a substituent include a group in which a phenyl group is bonded to the phenyl group via S or O.
Among these, R ³⁴ is preferably a group obtained by removing one hydrogen atom from an aromatic ring of an aromatic hydrocarbon, and particularly preferably a fluorenyl group.

Examples of the halogenated alkyl group for R ³⁵ include the same as the halogenated alkyl group for R ³³ , and a fluorinated alkyl group is preferable.
The fluorinated alkyl group in R ³⁵ preferably has 50% or more of the hydrogen atom of the alkyl group fluorinated, more preferably 70% or more, and even more preferably 90% or more. This is preferable because the strength of the acid is increased. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

  Specific examples of the acid generator (B1) include the following.

Specific examples of the acid generator (B1) include oxime sulfonate acid generators disclosed in WO2004 / 074242A2 (Examples 1 to 40 on pages 65 to 85).
Among the above, the acid generator (B1) is preferably the following two compounds.

An acid generator (B1) may be used individually by 1 type, and may be used in combination of 2 or more type.
In the component (B), the ratio of the acid generator (B1) is preferably in the range of 10 to 90% by mass, more preferably 20 to 80% by mass, for the effect of the present invention, and 30 to 30%. 70 mass% is further more preferable, and 40-60 mass% is the most preferable.

[Acid generator (B2)]
As the acid generator (B2), those that have been proposed as acid generators for chemically amplified resists can be used, and various types such as iodonium salts and sulfonium salts are known.
Examples of the acid generator (B2) include those having a cation moiety represented by the following general formula (b′-1) or (b′-2).

［式中、Ｒ^１”〜Ｒ^３”および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^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, and at least one of R ¹ ″ to R ³ ″ represents an aryl group. , R ⁵ ″ to R ⁶ ″ each represents an aryl group. ]

In formula (b′-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group, and at least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl 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 each preferably a phenyl group or a naphthyl 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. Of R ⁵ ″ to R ⁶ ″, two or more are preferably aryl groups, and all of R ⁵ ″ to R ⁶ ″ are most preferably aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
Examples of the alkyl group for R ⁵ ″ to R ⁶ ″ include the same as the alkyl group for R ¹ ″ to R ³ ″.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.

  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, dinaphthylmonophenylsulfonium Ion, and the like.

  As an onium salt acid generator having a cation moiety represented by the formula (b′-1) or (b′-2), more specifically, for example, the following general formula (b-1) or (b-2) ).

［式中、Ｒ^１”〜Ｒ^３”，Ｒ^５”〜Ｒ^６”は、それぞれ独立に、アリール基またはアルキル基を表し；Ｒ^４”は、直鎖、分岐または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

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

Formula ^{(b-1) R 1 "} ~R 3" in is the same as ^R 1 ^{"~R 3"} in the above-mentioned formula (b'-1).
^R 5 ^{"~R 6"} in formula (b-2) is the same as ^R 5 "to R ⁶ in the above formula (b'-1).

R ⁴ ″ in formulas (b-1) and (b-2) represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group.
The linear alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. 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.

  Moreover, as an onium salt type acid generator which has a cation part represented by Formula (b'-1) or (b'-2), in the said General formula (b-1) or (b-2), an anion part Is an onium salt-based acid generator in which the anion moiety represented by the following general formula (b-3) or (b-4) is substituted, that is, the general formula (b′-1) or (b′-2). The onium salt type acid generator which has a cation part represented and the anion part represented by the following general formula (b-3) or (b-4) is also mentioned.

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

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

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Preferably it is C3.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably It is C1-C7, More preferably, it is C1-C3.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, as the number of hydrogen atoms substituted with fluorine atoms increases, the strength of the acid increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Furthermore, as an onium salt acid generator other than the onium salt acid generator having a cation moiety represented by the formula (b′-1) or (b′-2), for example, the following general formula (b-0): The acid generator represented is mentioned.

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

[Wherein, R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, linear or A branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group; R ⁵³ is an aryl group which may have a substituent; u '' Is an integer of 1 to 3. ]

In the general formula (b-0), R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group.
The linear or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms, and most preferably 6 to 10 carbon atoms.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. Also. 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%, particularly hydrogen atoms. Are preferably substituted with a fluorine atom 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.

An acid generator (B2) may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, the acid generator (B2) preferably has a cation moiety represented by the general formula (b′-1) or (b′-2). It is more preferable that it has a cation part represented by), and in particular, those having a cation part in which R ¹ ″ to R ³ ″ are all aryl groups are preferable. By using such an onium salt-based acid generator, the EL margin is further improved, and the formed resist pattern is less prone to tailing and has a good shape. Among them, it is preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).
In the component (B), the ratio of the acid generator (B2) is preferably in the range of 10 to 90% by mass, more preferably 20 to 80% by mass for the effect of the present invention, and 30 to 30%. 70 mass% is further more preferable, and 40-60 mass% is the most preferable.

In the component (B), the mixing ratio (mass ratio) of the acid generators (B1) and (B2) is within the range of acid generator (B1): acid generator (B2) = 9: 1 to 1: 9. It is preferable that 8: 2 to 2: 8 is more preferable, 7: 3 to 3: 7 is more preferable, and 6: 4 to 4: 6 is most preferable. Within the above range, the acid generators (B1) and (B2) are well balanced, and the effect of the present invention is excellent.
Furthermore, in the present invention, the balance of the lithography properties can be adjusted by adjusting the mixing ratio of the acid generators (B1) and (B2) within the above range. For example, when importance is attached to DOF and resolution, the ratio of the acid generator (B1) is increased, and when priority is given to the EL margin, the ratio of the acid generator (B2) is increased.

The component (B) may further contain an acid generator (B3) other than the acid generators (B1) and (B2) described above as long as the effects of the present invention are not impaired.
The acid generator (B3) is not particularly limited as long as it is other than the acid generators (B1) and (B2) described above, and those that have been proposed as acid generators for chemically amplified resists so far are used. Can be used. Various acid generators have been known so far. For example, oxime sulfonate acid generators other than the acid generator (B1), bisalkyl or bisarylsulfonyldiazomethanes, poly ( Examples thereof include diazomethane acid generators such as bissulfonyl) diazomethanes, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, and disulfone acid generators.

Examples of the oxime sulfonate acid generator other than the acid generator (B1) include those in which R ³³ is a cyano group or an alkyl group having no substituent, in the general formula (B-1), Examples thereof include those in which R ³⁵ is an alkyl group having no substituent in B-1). Here, the “alkyl group having no substituent” preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms.
Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4- Nitrobenzenesulfonyloxyimino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (Benzenesulfonyloxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- (2-Chlorobenzenesulfoni Oxyimino) -4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyl) Oxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino)- 1-cyclopentenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino)- -Cyclooctenyl acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α -(Propylsulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) ) -1-cyclopentenylacetonitrile, 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 -(Trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxy) Imino)-p-methoxyphenyl acetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-(like methylsulfonyl oxyimino)-p-bromophenyl acetonitrile.

  Moreover, the compound represented by the following general formula (B-2) is mentioned as an oxime sulfonate type | system | group acid generator other than an acid generator (B1).

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

Specific examples of the compound represented by the general formula (B-2) are disclosed in JP-A-9-208554 (paragraphs [0012] to [0014], [Chemical 18] to [Chemical 19]). An oxime sulfonate-based acid generator can also be suitably used.
Preferable examples of the compound represented by the general formula (B-2) include the following.

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.

  As the acid generator (B3), one type of these acid generators may be used alone, or two or more types may be used in combination.

  The content of the component (B) in the positive resist composition of the present invention is preferably in the range of 2 to 30 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the component (A). 5 to 15 parts by mass is more preferable. 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.

<Optional 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, stability with time of standing, and the like. Can be blended.
Since a wide variety of components (D) have already been proposed, any known one may be used, but aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred. .
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms. Specific examples thereof include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n-heptylamine, Dialkylamines such as di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptyl Trialkylamines such as amine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n -Ok Noruamin, alkyl alcohol amines such as tri -n- octanol amine.
Among these, alkyl alcohol amines and / or trialkyl amines are preferable, trialkyl amines are more preferable, and alkyl amines having three alkyl groups having 5 to 8 carbon atoms such as tri-n-pentyl amine are most preferable.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

In the positive resist composition of the present invention, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof (E) is used as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape, retention stability, and the like. ) (Hereinafter referred to as component (E)).
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic 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.

  If desired, the positive resist composition of the present invention may further contain miscible additives such as an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, and a dissolution inhibitor. , Plasticizers, stabilizers, colorants, antihalation agents, dyes, and the like can be added 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. Conventionally, any one of 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 and derivatives thereof;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether;
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, etc. Can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among 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 blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA, PGME 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 99.9: 0.1.
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. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 5-15% by mass.

≪Resist pattern formation method≫
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 with a spinner, and prebaking (PAB) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. After this, ArF excimer laser light is selectively exposed through a desired mask pattern using, for example, an ArF exposure apparatus, and then subjected to PEB (post-exposure heating) for 40 to 120 seconds under a temperature condition of 80 to 150 ° C. , Preferably 60-90 seconds. Subsequently, this is developed using an alkaline developer, for example, an aqueous 0.1 to 10% by mass tetramethylammonium hydroxide solution. In this way, a resist pattern faithful to the mask pattern can be obtained.
An antireflection film may be provided between the substrate and the coating layer of the resist composition.
The wavelength used for the exposure is not particularly limited, and 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 according to the present invention is particularly effective for an ArF excimer laser.

The present invention is particularly preferably applied to a substrate provided with an antireflection film [an organic antireflection film (an antireflection film made of an organic compound) or an inorganic antireflection film (an antireflection film made of an inorganic compound)]. Particularly preferred is an organic antireflection film. This is particularly true when using a substrate provided with an antireflection film (organic antireflection film or inorganic antireflection film), particularly a resist pattern in contact with the antireflection film, when using a substrate provided with an organic antireflection film. This is because a phenomenon tends to occur, but this can be reduced by applying the present invention.
Examples of the organic antireflection film include AR-29 and AR-46 (both product names) manufactured by Shipley. In particular, when the AR-46 is used, the trailing phenomenon is likely to occur. However, the application of the present invention can sufficiently suppress the trailing phenomenon even when the AR-46 is used.

As described above, according to the positive resist composition and the resist pattern forming method of the present invention, both DOF and EL margin can be achieved.
Although the reason is not clear, it is considered that some synergistic effect is caused by using both (B) -1 and (B) -2 described above as the component (B).
That is, when an oxime sulfonate acid generator is used alone, the DO margin tends to be good but the EL margin tends to be poor. On the other hand, onium salt-based acid generators usually have strong acid strength and a good EL margin, but have a poor DOF. When these acid generators are combined, the DOF and EL margin are predicted to be average values when each is used alone.
However, in the present invention, by using the specific oxime sulfonate acid generator (B) -1 in combination with the onium salt acid generator, each of the DOF and EL margin characteristics is not impaired. Excellent DOF and EL margin equal to or better than those used alone are achieved. From this, it can be inferred that some synergistic effect is generated that cannot be predicted from the case where each of them is used alone.

In the present invention, the shape of the formed resist pattern is also good. Conventionally, when an oxime sulfonate-based acid generator is used, a lower end portion of a longitudinal section of a resist pattern is tapered, so-called tailing occurs, and a pattern having a good shape may not be obtained. On the other hand, in the present invention, the rectangular shape of the cross-sectional shape is high, and a resist pattern with a good shape can be obtained.
Further, since the resist pattern has a good shape, the resolution is also good.
Furthermore, in the present invention, since the EL margin is large and a resist pattern faithful to the mask can be formed, the ID bias is also improved. The ID bias is a characteristic that allows a resist pattern faithful to a mask to be formed when exposure is performed using a mask including patterns having different dimensions and shapes. If the ID bias is poor, the pattern is dense (dense ( Even if the pattern dimension in the mask is the same between the (dense) pattern) and the non-dense part (iso (iso) pattern), a dimensional difference occurs in the formed resist pattern. Such a problem is particularly noticeable when proximity exposure is performed in which a gap is provided between the mask and the resist for exposure. Such a problem is considered to be caused by a difference in exposure amount due to pattern density. However, in the present invention, even if the EL margin is large and the exposure amount is deviated to some extent, a resist pattern faithful to the mask can be obtained, and it is estimated that the ID bias is thereby improved.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
Example 1, Comparative Examples 1-2
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition solution.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(A) -1: a copolymer represented by the following formula (A) -1.
(B) -1: a compound represented by the following formula (B) -1.
(B) -2: A compound represented by the following formula (B) -2 ((1,1′-dinaphthyl) phenylsulfonium nonafluorobutanesulfonate).
(D) -1: tri-n-pentylamine.
(E) -1: salicylic acid.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.
(S) -2: γ-butyrolactone.

The following evaluation was performed using the obtained positive resist composition solution. The results are shown in Table 2.
<EL margin evaluation>
An organic antireflection film composition “AR46” (trade name, manufactured by Rohm and Haas) is applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a film thickness of 32 nm was formed. The positive resist composition solution obtained above is applied onto the antireflection film using a spinner, prebaked (PAB) for 90 seconds at a PAB temperature shown in Table 2 on a hot plate, and then dried. As a result, a resist film having a thickness of 200 nm was formed.
Next, ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S306C (manufactured by Nikon Corporation; NA (numerical aperture) = 0.78, Y-Dipole).
Then, PEB (post-exposure heating) was carried out at the PEB temperature shown in Table 2 for 90 seconds, and further developed at 23 ° C. with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds. The substrate was washed with water for 2 seconds, dried, and further post-baked at 100 ° C. for 60 seconds to form a contact hole (CH) pattern having a diameter of 100 nm and a pitch of 200 nm.
At this time, the optimal exposure dose (mJ / cm ² ) when a 100 nm CH pattern is formed at a pitch of 200 nm is Eop, and the 100 nm CH pattern obtained in the Eop is observed by SEM (scanning electron microscope). Then, the amount of exposure that can form each pattern with a target dimension (100 nm) within a range of ± 10% (that is, 90 to 110 nm) is within what percentage of Eop determined above (EL margin). . The results are shown in Table 2.

<DOF evaluation>
In the EL margin evaluation, the exposure amount is constant at Eop (mJ / cm ² ) obtained above, the CH pattern is formed by appropriately shifting the focus up and down, and the CH pattern has a dimensional change rate of 100 nm ± 10% in diameter. The width (μm) of the depth of focus (DOF) obtained within the range of was determined. The results are shown in Table 2.

<Shape>
The upper surface and cross-sectional shape of the CH pattern having a diameter of 100 nm and a pitch of 200 nm formed as described above were observed with an SEM and evaluated according to the following criteria. The results are shown in Table 2.
○: Shape with excellent rectangularity with high verticality of the inner wall.
×: Bottomed shape or rounded top part.

As described above, in Example 1 using the mixture of (B) -1 and (B) -2 as the component (B), the EL margin and the DOF were both equal to or higher than those of Comparative Examples 1 and 2. Also, the shape of the hole was good, for example, the cross-sectional shape was highly rectangular. Also, the shape seen from above was good because the roundness of the hole was high.
On the other hand, Comparative Example 1 using only (B) -1 as the component (B) had a small EL margin. Moreover, the comparative example 2 which used only (B) -2 as (B) component had small DOF. Further, in both Comparative Examples 1 and 2, the shape of the pattern was poor. For example, the cross-sectional shape was low in rectangularity such as the top portion being rounded. The shape seen from above also had a low roundness of the hole.

Claims (6)

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 an acrylate ester containing an acid dissociable, dissolution inhibiting group, represented by the following general formula (a1-1-02):
The acid generator component (B) has an oxime sulfonate-based acid generator (B1) represented by the following general formula (B-1) and a cation moiety represented by the following general formula (b′-1). A positive resist composition comprising an onium salt acid generator (B2).

[Wherein, R represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms , R ¹² represents an alkyl group having 1 to 5 carbon atoms, and h represents Represents an integer of 1 to 3; ]

Wherein ^{(B-1), R 33} is a halogenated alkyl ^{group, R 34} is an aryl ^{group, R 35} is a halogenated alkyl group. ]

[Wherein, two of R ¹ ″ to R ³ ″ represent a naphthyl group, and one represents a phenyl group. ]   2. The positive type according to claim 1, wherein a mixing ratio (mass ratio) of the oxime sulfonate-based acid generator (B1) and the onium salt-based acid generator (B2) is within a range of 9: 1 to 1: 9. Resist composition. The positive resist composition according to claim 1 or 2, wherein the resin component (A) further comprises a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group. The positive resist according to any one of claims 1 to 3, wherein the resin component (A) further includes a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. Composition. Furthermore, the positive resist composition as described in any one of Claims 1-4 containing a nitrogen-containing organic compound (D). A step of forming a resist film on a substrate using the positive resist composition according to any one of claims 1 to 5 , a step of exposing the resist film, and developing the resist film to form a resist pattern A resist pattern forming method including the step of: