JP5438940B2 - Resist composition and resist pattern forming method - Google Patents

Description

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

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 light 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. Further, F ₂ excimer laser having a shorter wavelength than these excimer lasers, electron beams, also studied including EUV (extreme ultraviolet), X-rays have been made (for example, see Patent Documents 1 and 2).

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 composition containing a base material component whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. ing.
For example, as a positive chemically amplified resist composition, a composition containing a resin component (base resin) whose solubility in an alkaline developer is increased by the action of an acid and an acid generator component is generally used. Yes. When such a resist film formed using the resist composition is selectively exposed at the time of forming the resist pattern, an acid is generated from the acid generator in the exposed portion, and the alkali developer of the resin component is generated by the action of the acid. As a result, the exposed area becomes soluble in an alkaline developer.
At present, as the chemically amplified positive resist, for example, a group in which a hydroxyl group of a polyhydroxystyrene resin or a carboxy group of a (meth) acrylic resin is protected with an acid dissociable, dissolution inhibiting group ( For example, see Patent Document 3).
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.

As the acid generator used in the chemically amplified resist composition, various kinds of acid generators have been proposed so far, for example, onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, Diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like are known.
Currently, an onium salt acid generator having an onium ion such as triphenylsulfonium in the cation moiety is used as the acid generator. The anion moiety of the onium salt acid generator is generally an alkyl sulfonate ion or a fluorinated alkyl sulfonate ion in which part or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms (for example, Patent Documents). 4).
JP 2003-75998 A JP 2003-140361 A JP 2003-241385 A Japanese Patent Laid-Open No. 2005-37888

  Currently, there is a demand for providing a new resist material that can meet the demand for improvement in lithography properties such as high resolution. That is, it is desired to provide a resist material that can be applied to lithography using an electron beam or EUV, which may be able to realize further high resolution. However, these lithography processes using an electron beam or EUV require a depressurization operation at the time of exposure and the like, and therefore take a longer time than processes using an excimer laser or the like. In particular, direct writing with an electron beam requires a long time for patterning. Therefore, a resist material used in a process using an electron beam or EUV is required to improve sensitivity from the viewpoint of increasing throughput. However, conventional resist materials are not satisfactory in terms of sensitivity when used for lithography using electron beams or EUV.

The present invention has been made in view of the above circumstances, and in lithography of a resist film using an ArF excimer laser, an F ₂ excimer laser, EUV, an electron beam, or the like, the sensitivity can be improved without impairing the resolution. A positive resist composition and a resist pattern forming method can be provided.

［式中、Ｒ ^１１ は水素原子または置換基を有していても良い炭素数１〜５のアルキル基であり；Ｒ ^１１ ’は水素原子または置換基を有していても良い炭素数１〜５のアルキル基であり；前記Ｒ ^１１ 、Ｒ ^１１ ’は相互に結合して環を形成しても良く；Ｒ ^１２ 〜Ｒ ^１４ 、Ｒ ^１４’ は、それぞれ独立に、水素原子または置換基を有していても良い炭素数１〜３０の炭化水素基であり、相互に結合して環を形成していても良い。］ In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention includes a base component (A) whose solubility in an alkaline developer is increased by the action of an acid, an acid generator component (B) that generates an acid upon exposure, and benzodioxole Or a positive resist composition containing the derivative (G) thereof, wherein the (G) comprises benzodioxole represented by the following general formula (g1) or a derivative (G1) thereof, ) In a range of 50 to 150 parts by mass with respect to 100 parts by mass of the base component (A) .

[Wherein, R ¹¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent ; R ¹¹ ′ is a carbon atom having 1 to 1 carbon atoms which may have a hydrogen atom or a substituent ; R ¹¹ and R ¹¹ ′ may be bonded to each other to form a ring; R ^{12 to} R ¹⁴ and R ^{14 ′} each independently have a hydrogen atom or a substituent. The hydrocarbon group having 1 to 30 carbon atoms which may be bonded to each other to form a ring. ]

  According to a second aspect of the present invention, there is provided a step of forming a resist film on a support using the resist composition of the first aspect, a step of exposing the resist film, and an alkali development of the resist film. A resist pattern forming method including a step of forming a resist pattern.

In the present specification and claims, “aliphatic” is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do not have aromaticity.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
Unless otherwise specified, the “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
The “halogenated alkyl group” is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
“Fluorinated alkyl group” or “fluorinated alkylene group” refers to a group in which part or all of the hydrogen atoms of an alkyl group or alkylene group are substituted with fluorine atoms.
“Structural unit” means a monomer unit (monomer unit) constituting a polymer compound (polymer, copolymer).
“Exposure” is a concept including general irradiation of radiation.

According to the present invention, in a lithography using ArF excimer laser, F ₂ excimer laser, EUV or electron beam, the sensitivity can be increased without degrading resolution, and the positive resist composition is excellent in LWR (line width roughness). And a resist pattern forming method.

≪Resist composition≫
The positive resist composition according to the first aspect of the present invention comprises a base component (A) (hereinafter referred to as “component (A)”) whose solubility in an alkaline developer is increased by the action of an acid, and exposure. It contains an acid generator component (B) that generates an acid (hereinafter referred to as “component (B)”).
The component (A) is hardly soluble in an alkali developer before exposure. When an acid is generated from the component (B) by exposure, the solubility in the alkali developer is increased by the action of the acid. Therefore, when a resist film formed using such a positive resist composition is selectively exposed at the time of resist pattern formation, the solubility of the exposed portion of the resist film in an alkaline developer increases while the resist film is unexposed. Since the solubility of the portion in the alkali developer does not change, the exposed portion is dissolved and removed by alkali development, so that a resist pattern is formed.
In addition to these components (A) and (B), the resist composition of the present invention further contains benzodioxole or its derivative (G) (hereinafter referred to as “(G) component”).

<(A) component>
As the component (A), organic compounds that are usually used as base material components for chemically amplified resists can be used singly or in combination of two or more.
Here, the “base material component” is an organic compound having a film forming ability, and an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film-forming ability is improved and a nano-level resist pattern is easily formed.
The organic compound having a molecular weight of 500 or more includes a low molecular weight organic compound having a molecular weight of 500 or more and less than 2000 (hereinafter referred to as “low molecular compound”) and a high molecular weight resin having a molecular weight of 2000 or more (polymer material). Broadly divided. As the low molecular weight compound, a non-polymer is usually used. In the case of a resin (polymer, copolymer), a polystyrene-reduced mass average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” refers to a resin having a molecular weight of 2000 or more.
As the component (A), a resin whose alkali solubility is changed by the action of an acid can be used, and a low molecular weight material whose alkali solubility is changed by the action of an acid can also be used.

In the positive resist composition of the present invention, the component (A) is a resin component (A1) whose solubility in an alkaline developer is increased by the action of an acid (hereinafter sometimes referred to as “(A1) component”). It may be a low molecular compound component (A2) (hereinafter sometimes referred to as “component (A2)”) whose solubility in an alkaline developer is increased by the action of an acid, or a mixture thereof. May be.
Among these, it is preferable that (A) component contains (A1) component.

[(A1) component]
As the component (A1), resin components (base resins) that are usually used as base components for chemically amplified resists can be used singly or in combination of two or more.
In the present invention, the component (A) preferably includes a structural unit (a1) derived from hydroxystyrene described later and a structural unit (a2) including an acid dissociable, dissolution inhibiting group described later.

[Structural unit (a1)]
The structural unit (a1) is a structural unit derived from hydroxystyrene. When the component (A) has the structural unit (a1), the effects of the present invention can be improved. Furthermore, the structural unit (a1) also has the advantage that the raw material hydroxystyrene is readily available and is inexpensive.
Here, “hydroxystyrene” is a concept including hydroxystyrene and those in which the α-position hydrogen atom of hydroxystyrene is substituted with another substituent such as an alkyl group or a halogenated alkyl group, and derivatives thereof. And
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、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 lower alkyl group or a halogenated lower alkyl group; R ⁶ is a lower alkyl group; p is an integer of 1 to 3; Is an integer. ]

In general formula (a-1), the lower alkyl group of R is an alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl. And linear or branched alkyl groups such as a group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. Among these, a methyl group is preferable.
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 pentafluoroethyl 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 45 to 90 mol%, more preferably 60 to 90 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 containing an acid dissociable, dissolution inhibiting group. The acid dissociable, dissolution inhibiting group in the structural unit (a2) has an alkali dissolution inhibiting property that makes the entire component (A) hardly soluble in an alkali developer before dissociation, and dissociates with an acid. This increases the solubility of the entire component in an alkaline developer, and those that have been proposed as acid dissociable, dissolution inhibiting groups for base resins for chemically amplified resists can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group in (meth) acrylic acid, etc .; an acetal type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group, a hydrogen atom of a hydroxystyrene hydroxyl group One in which a part of atoms is substituted with an acetal type acid dissociable, dissolution inhibiting group is widely known. The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

Here, “aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
Examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a group represented by -C (R ⁷¹ ) (R ⁷² ) (R ⁷³ ). ^Wherein, R 71 ^{to R 73} each independently represents a linear alkyl group of 1 to 5 carbon atoms. The group represented by —C (R ⁷¹ ) (R ⁷² ) (R ⁷³ ) preferably has 4 to 8 carbon atoms, specifically a tert-butyl group or a 2-methyl-2-butyl group. , 2-methyl-2-pentyl group, 3-methyl-3-pentyl group and the like. A tert-butyl group is particularly preferable.

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

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

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

[Wherein, R represents a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹⁵ and R ^{16 each} represents an alkyl group (which may be linear or branched, and preferably has 1 to 5 carbon atoms. Is). ]

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

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

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

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

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

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

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

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

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

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

Among these, an acetal type acid dissociable, dissolution inhibiting group is preferable because of excellent lithography properties such as resolution and pattern shape,
The structural unit represented by the following general formula (a2-1) or (a2-2) is more preferable. When the component (A) has the structural unit (a2) and the structural unit (a1), lithography properties such as resolution and pattern shape can be improved.

［式（ａ２−１）中、Ｒは水素原子、低級アルキル基またはハロゲン化低級アルキル基であり；Ｒ^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 is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹ and R ² are each independently a hydrogen atom or a lower alkyl group; Y ¹ is a lower alkyl group; A group or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0 to 3. In formula (a2-2), R is as defined above; R ³ and R ⁴ are each independently a hydrogen atom or a lower alkyl group; 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. ]

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 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.
At least one of R ¹ and R ² 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. In order to improve 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 10 to 55 mol%, more preferably from 10 to 40 mol%, more preferably from 20 to 40, 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, “styrene” is a concept including styrene and those in which the α-position hydrogen atom of styrene is substituted with another substituent such as an alkyl group or a halogenated alkyl group. “Structural unit derived from styrene” means a structural unit formed by cleavage of an ethylenic double bond of styrene. In styrene, the hydrogen atom of the phenyl group may be substituted with a substituent such as an alkyl group having 1 to 5 carbon atoms.
As a suitable thing of a structural unit (a4), the structural unit represented by the following general formula (a4-1) can be illustrated.

［式中、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 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 preferably 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 group. 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. If it is smaller than the upper limit of this range, there is sufficient solubility in a resist solvent to be used as a resist, and if 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. . Mn represents a number average molecular weight.

<(B) component>
The component (B) is not particularly limited, and those that have been proposed as acid generators for chemically amplified resists can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

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

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

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

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

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

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

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

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

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

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

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

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Most preferably, it has 3 carbon atoms.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably Has 1 to 7 carbon atoms, more preferably 1 to 3 carbon atoms.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, 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.

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

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

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

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

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

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

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

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

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

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 for R ³³ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and more preferably carbon atoms. Numbers 1 to 6 are most preferable.
R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.
The fluorinated alkyl group for R ³³ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred.

As the aryl group of R ³⁴ , one hydrogen atom is removed from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, or a phenanthryl group. And 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.
The fluorinated alkyl group for R ³⁵ is preferably such that the hydrogen atom of the alkyl group is 50% or more fluorinated, more preferably 70% or more fluorinated, and 90% or more fluorinated. Particularly preferred is the strength of the acid generated. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Further, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO2004 / 074242A2 (pages 65 to 85). The oxime sulfonate acid generators disclosed in Examples 1 to 40) of No. 1 can also be suitably used.
Moreover, the following can be illustrated as a suitable thing.

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

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).

The content of the component (B) in the positive resist composition of the present invention is preferably 0.5 to 50 parts by weight, more preferably 1 to 40 parts by weight, and more preferably 10 to 40 parts by weight with respect to 100 parts by weight of the component (A). Part by mass is most preferred.
By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(G) component>
The resist composition of the present invention contains benzodioxole or its derivative (G).
The benzodioxole or derivative thereof is not particularly limited as long as it has a benzodioxole skeleton, but benzodioxole or derivative thereof represented by the following general formula (g1) (hereinafter referred to as “(G1) component”) "). The component (G) in the present invention can be used as a sensitivity improver.

In the general formula (g1), R ¹¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent, and R ¹¹ ′ may have a hydrogen atom or a substituent. R ¹¹ and R ¹¹ ′ may be bonded to each other to form a ring; R ^{12 to} R ¹⁴ and R ^{14 ′} are each independently a hydrogen atom or a C 1-5 alkyl group; It is a C1-C30 hydrocarbon group which may have a substituent, and may combine with each other to form a ring.

Among the alkyl groups having 1 to 5 carbon atoms that may have a substituent in R ¹¹ and R ^{11 ′, as} the unsubstituted alkyl group having 1 to 5 carbon atoms, specifically, a methyl group, Examples include an ethyl group, n-propyl group, i-propyl group, n-butyl group, tert-butyl, group and the like. The “C1-5” does not include the carbon number of the substituent. Examples of the substituent include a lower alkyl group, a fluorine atom, a fluorinated lower alkyl group substituted with a fluorine atom, an oxygen atom (═O), and a hydroxy group.
Moreover, the carbon atom which comprises the said C1-C4 alkylene group may be substituted by the substituent containing a hetero atom. Specific examples of the substituent containing a heteroatom include —O—, —C (═O) —O—, —C (═O) —, —O—C (═O) —O—, —C (═O) —NH—, —NH— (H may be substituted with a substituent such as an alkyl group, an acyl group, etc.), —S—, —S (═O) ₂ —, —S ( ═O) ₂ —O— and the like.
Among ^{these, 'if} both are hydrogen ^atoms, R 11, ^{R 11'} R 11, ^{R 11} when both are an alkyl group of 1 to 5 carbon ^{atoms, R 11} is a hydrogen atom, ^{R 11 '} The case of an alkyl group having 1 to 5 carbon atoms is preferable because of excellent lithography properties such as resolution and resist pattern shape. Moreover, it is preferable because sensitivity is improved.

The hydrocarbon group having 1 to 30 carbon atoms which may have a substituent in R ^{12 to} R ¹⁴ and R ^{14 ′} may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. There may be.

The aromatic hydrocarbon group is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30, more preferably 5 to 20, still more preferably 6 to 15, and most preferably 6 to 12. However, the carbon number does not include the carbon number in the substituent.
Specific examples of the aromatic hydrocarbon group include a hydrogen atom from an aromatic hydrocarbon ring such as a phenyl group, a biphenyl group, a fluorenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. And arylalkyl groups such as aryl group, benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group and the like. The number of carbon atoms in the alkyl chain in the arylalkyl group is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 to 2.
The aromatic hydrocarbon group may have a substituent. For example, a part of carbon atoms constituting the aromatic ring of the aromatic hydrocarbon group may be substituted with a hetero atom, and the hydrogen atom bonded to the aromatic ring of the aromatic hydrocarbon group is substituted with the substituent. May be.
Examples of the former include heteroaryl groups in which some of the carbon atoms constituting the ring of the aryl group are substituted with heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and aromatic hydrocarbons in the arylalkyl groups. Examples include heteroarylalkyl groups in which some of the carbon atoms constituting the ring are substituted with the above heteroatoms.
Examples of the substituent of the aromatic hydrocarbon group in the latter example include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and an oxygen atom (═O).
The alkyl group as a substituent of the aromatic hydrocarbon group is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. preferable.
The alkoxy group as a substituent of the aromatic hydrocarbon group is preferably an alkoxy group having 1 to 5 carbon atoms, and is a methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert- A butoxy group is preferable, and a methoxy group and an ethoxy group are most preferable.
Examples of the halogen atom as a substituent for the aromatic hydrocarbon group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.
Examples of the halogenated alkyl group as a substituent of the aromatic hydrocarbon group include an alkyl group having 1 to 5 carbon atoms, such as an alkyl group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, and a tert-butyl group. And a group in which part or all of the hydrogen atoms are substituted with the halogen atoms.

The aliphatic hydrocarbon group in R ^{12 to} R ¹⁴ and R ^{14 ′} in the general formula (g1) may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. . The aliphatic hydrocarbon group may be linear, branched or cyclic.
In R ^{12 to} R ¹⁴ and R ^{14 ′} in the general formula (g1), the aliphatic hydrocarbon group is substituted with a substituent in which a part of carbon atoms constituting the aliphatic hydrocarbon group includes a hetero atom. Or a part or all of the hydrogen atoms constituting the aliphatic hydrocarbon group may be substituted with a substituent containing a hetero atom.
The “heteroatom” is not particularly limited as long as it is an atom other than a carbon atom and a hydrogen atom, and examples thereof include a halogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom.
The substituent containing a hetero atom may be composed of only the hetero atom, or may be a group containing a group or atom other than the hetero atom.
Specific examples of the substituent for substituting a part of carbon atoms of the aliphatic hydrocarbon group include, for example, —O—, —C (═O) —O—, —C (═O) —, —O—. C (═O) —O—, —C (═O) —NH—, —NH— (H may be substituted with a substituent such as an alkyl group or an acyl group), —S—, —S ( ═O) ₂ —, —S (═O) ₂ —O— and the like. When the aliphatic hydrocarbon group is cyclic, these substituents may be included in the ring structure.
Specific examples of the substituent for substituting part or all of the hydrogen atoms of the aliphatic hydrocarbon group include, for example, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, an oxygen atom (= O), a cyano group, and the like. Is mentioned.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group or a tert-butoxy group, and a methoxy group or an ethoxy group. Is most preferred.
As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.
As the halogenated alkyl group, a part or all of hydrogen atoms of an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, etc. And a group substituted with a halogen atom.

Examples of the aliphatic hydrocarbon group include a linear or branched saturated hydrocarbon group, a linear or branched monovalent unsaturated hydrocarbon group, or a cyclic aliphatic hydrocarbon group (aliphatic A cyclic group) is preferred.
The linear saturated hydrocarbon group (alkyl group) preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms. Specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decanyl group, undecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group Group, pentadecyl group, hexadecyl group, isohexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group and the like.
The branched saturated hydrocarbon group (alkyl group) preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms. Specifically, for example, 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, Examples include 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group and the like.

As said unsaturated hydrocarbon group, it is preferable that carbon number is 2-10, 2-5 are preferable, 2-4 are preferable, and 3 is especially preferable. Examples of the linear monovalent unsaturated hydrocarbon group include a vinyl group, a propenyl group (allyl group), and a butynyl group. Examples of the branched monovalent unsaturated hydrocarbon group include a 1-methylpropenyl group and a 2-methylpropenyl group.
Among the above, the unsaturated hydrocarbon group is particularly preferably a propenyl group.

The cyclic aliphatic hydrocarbon group (aliphatic cyclic group) in R ^{12 to} R ¹⁴ and R ^{14 ′} in the general formula (g1) may have a substituent and has 3 to 30 carbon atoms. An aliphatic cyclic group.
In the aliphatic cyclic group, a part of carbon atoms constituting the aliphatic cyclic group may be substituted with a substituent containing a hetero atom, and one of the hydrogen atoms constituting the aliphatic cyclic group. Part or all of them may be substituted with a substituent containing a hetero atom.
The “heteroatom” is not particularly limited as long as it is an atom other than a carbon atom and a hydrogen atom, and examples thereof include a halogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, an iodine atom, and a bromine atom.
The substituent containing a hetero atom may be composed of only the hetero atom, or may be a group containing a group or atom other than the hetero atom.
Specifically as a substituent which substitutes a part of carbon atom which comprises the said aliphatic cyclic group, for example, -O-, -C (= O) -O-, -C (= O)-, -O -C (= O) -O-, -C (= O) -NH-, -NH- (H may be substituted with a substituent such as an alkyl group or an acyl group), -S-, -S (═O) ₂ —, —S (═O) ₂ —O— and the like can be mentioned. These substituents may be contained in the ring structure.
Specific examples of the substituent that substitutes part or all of the hydrogen atoms of the aliphatic cyclic group include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, an oxygen atom (═O), and a cyano group. Can be mentioned.
The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group or a tert-butoxy group, and a methoxy group or an ethoxy group. Is most preferred.
As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, A fluorine atom is preferable.
As the halogenated alkyl group, a part or all of hydrogen atoms of an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, etc. And a group substituted with a halogen atom.

The aliphatic cyclic group may be a monocyclic group or a polycyclic group. The number of carbon atoms is 3 to 30, preferably 5 to 30, more preferably 5 to 20, still more preferably 6 to 15, and particularly preferably 6 to 12.
Specifically, for example, a group in which one or more hydrogen atoms have been removed from a monocycloalkane; a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as bicycloalkane, tricycloalkane, tetracycloalkane, etc. Can be mentioned. More specifically, a group in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane; Examples include a group excluding a hydrogen atom.
When the aliphatic cyclic group does not contain a substituent containing a hetero atom in the ring structure, the aliphatic cyclic group is preferably a polycyclic group, and has one or more hydrogen atoms from the polycycloalkane. Excluded groups are preferred, and most preferred are groups in which one or more hydrogen atoms have been removed from adamantane.
When the aliphatic cyclic group includes a substituent containing a hetero atom in the ring structure, examples of the substituent containing a hetero atom include —O—, —C (═O) —O—, —S—. , —S (═O) ₂ — and —S (═O) ₂ —O— are preferable. Specific examples of the aliphatic cyclic group include the following formulas (L1) to (L5), (S1) to (S4), and the like.

［式中、Ｑ”は炭素数１〜５のアルキレン基、−Ｏ−、−Ｓ−、−Ｏ−Ｒ^９４−または−Ｓ−Ｒ^９５−であり、Ｒ^９４およびＲ^９５はそれぞれ独立に炭素数１〜５のアルキレン基であり、ｍは０または１の整数である。］

[Wherein, Q ″ is an alkylene group having 1 to 5 carbon atoms, —O—, —S—, —O—R ⁹⁴ — or —S—R ⁹⁵ —, and R ⁹⁴ and R ⁹⁵ are each independently carbon. An alkylene group of 1 to 5 and m is an integer of 0 or 1.]

In the formula, each of the alkylene groups in Q ″, R ⁹⁴ and R ⁹⁵ is preferably a linear or branched alkylene group, and the alkylene group has 1 to 5 carbon atoms and 1 to 3 carbon atoms. It is preferable.
Specific examples of the alkylene group include a methylene group [—CH ₂ —]; —CH (CH ₃ ) —, —CH (CH ₂ CH ₃ ) —, —C (CH ₃ ) ₂ —, —C ( _{CH 3) (CH 2 CH 3} ) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as ethylene group _[-CH 2 CH _2— ]; —CH (CH ₃ ) CH ₂ —, —CH (CH ₃ ) CH (CH ₃ ) —, —C (CH ₃ ) ₂ CH ₂ —, —CH (CH ₂ CH ₃ ) CH ₂ —, Alkylethylene groups such as —CH (CH ₂ CH ₃ ) CH ₂ —; trimethylene group (n-propylene group) [—CH ₂ CH ₂ CH ₂ —]; —CH (CH ₃ ) CH ₂ CH ₂ —, —CH _{2 CH (CH 3) CH 2} - alkyl trimethylene group and the like; Toramechiren group _{[-CH 2 CH 2 CH 2 CH} 2 -]; - CH (CH 3) CH 2 CH 2 CH 2 -, - CH 2 CH (CH 3) CH 2 CH 2 - alkyl tetramethylene group and the like; penta And methylene group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —] and the like.

In these aliphatic cyclic groups, a part of hydrogen atoms bonded to carbon atoms constituting the ring structure may be substituted with a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and an oxygen atom (═O).
As said alkyl group, a C1-C5 alkyl group is preferable, and it is especially preferable that they are a methyl group, an ethyl group, a propyl group, n-butyl group, and a tert- butyl group.
Examples of the alkoxy group and the halogen atom are the same as those exemplified as the substituent for substituting part or all of the hydrogen atoms.

In the present invention, the aliphatic cyclic group which may have a substituent in R ^{12 to} R ¹⁴ and R ^{14 ′} in the general formula (g1) may have a substituent. Polycyclic aliphatic cyclic groups are preferred. The polycyclic aliphatic cyclic group is preferably a group obtained by removing one or more hydrogen atoms from the polycycloalkane, (L2) to (L5), (S3) to (S4), and the like.

When any two or more of R ^{12 to} R ¹⁴ and R ^{14 ′ in} the general formula (g1) are an optionally substituted hydrocarbon group having 1 to 30 carbon atoms, May be bonded to each other to form a ring. The ring formed may be monocyclic or polycyclic. The number of carbon atoms is preferably 5-30 (including bonded carbon atoms), more preferably 5-20.
Specifically, among the cyclic aliphatic hydrocarbon groups (aliphatic cyclic groups) in R ^{12 to} R ¹⁴ and R ^{14 ′} described above (assuming that the bonded carbon atom is also part of the ring), carbon An aliphatic cyclic group of several 5-30 is mentioned.

In the present invention, R ^{12 to} R ¹⁴ and R ^{14 ′} in the general formula (g1) are preferably a hydrogen atom or a lower alkyl group which may have a substituent, and are a hydrogen atom. Is most preferred.

  Specific examples (g1-1) to (g1-13) of benzodioxole represented by the general formula (g1) or a derivative thereof are listed below.

As the component (G1), one type may be used alone, or two or more types may be used in combination.
In the component (G), the proportion of the component (G1) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 75% by mass or more, and 100% by mass with respect to the total mass of the component (G). May be sufficient, and it is most preferable that it is 100 mass%. The effect of this invention improves that the ratio of (G1) component is more than the lower limit of the said range.

  Benzodioxole or its derivative (G) can be synthesized by a known method (for example, the method described in JP-A No. 11-29566), or a commercially available product can be used.

[(G2) component]
In the component (G), benzodioxole other than the component (G1) or a derivative thereof (G2) (hereinafter referred to as “(G2) component”) may be used in combination with the component (G1).
The component (G2) is not particularly limited as long as it does not impair the effects of the present invention and is other than the component (G1).

  The total mass of the entire component (G) in the resist composition of the present invention is preferably 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and most preferably 20 to 100 parts by mass with respect to 100 parts by mass of the component (A). preferable. The effect of this invention improves because content of (G) component is more than a lower limit. On the other hand, by being below the upper limit, it is possible to balance with components other than the component (G) in the resist composition of the present invention, and to form a good resist pattern.

<(D) component>
The positive resist composition may contain a nitrogen-containing organic compound component (D) (hereinafter referred to as “component (D)”) as an optional component.
The component (D) is not particularly limited as long as it acts as an acid diffusion control agent, that is, a quencher that traps the acid generated from the component (B) by exposure, and a variety of components have already been proposed. Therefore, any known one may be used, and aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are particularly preferable. 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, etc .; 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.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component. By setting the content in the above range, the resist pattern shape, the stability over time, and the like are improved.

<Optional component>
[(E) component]
The positive resist composition of the present invention includes, as optional components, organic carboxylic acids, phosphorus oxoacids and derivatives thereof for the purpose of preventing sensitivity deterioration, improving the resist pattern shape, 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.

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

The resist composition of the present invention described above is a novel one that has not been known so far.
According to the resist composition of the present invention, for example, when a line-and-space resist pattern is formed, the resist pattern can be formed with a smaller exposure amount than before without impairing the resolution. That is, “sensitivity” which is one of resist characteristics can be further improved. The reason why such an effect is obtained is not certain but is presumed as follows.
The positive resist composition of the present invention contains benzodioxole or a derivative thereof as the component (G). In resist pattern formation using the positive resist composition, the acid generated from the component (B) upon exposure hydrolyzes the acetal group of the component (G), whereby the aromatic ring skeleton of the component (G) As a result of the appearance of two hydroxyl groups, it is considered that the positive resist film is more easily dissolved in an alkaline developer. That is, since the ratio of the solubility of the exposed portion of the resist film to the unexposed portion with respect to an alkaline developer is larger than that of a conventional resist composition, the “sensitivity”, which is one of the lithography characteristics, is improved and good. It is presumed that the resist pattern can be formed.

≪Resist pattern formation method≫
The resist pattern forming method according to the second aspect of the present invention includes a step of forming a resist film on a support using the positive resist composition according to the first aspect of the present invention, a step of exposing the resist film, And a step of developing the resist film to form a resist pattern.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is coated on a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90, under a temperature condition of 80 to 150 ° C. For example, ArF excimer laser light is selectively exposed through a desired mask pattern using an ArF exposure apparatus or the like, and then subjected to PEB (post-exposure heating) at a temperature of 80 to 150 ° C. for 40 to 120. Second, preferably 60-90 seconds. Subsequently, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide (TMAH), preferably rinsed with pure water and dried. In some cases, a baking process (post-bake) may be performed after the development process. In this way, a resist pattern faithful to the mask pattern can be obtained.

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

The wavelength used for 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 is effective for KrF excimer laser, ArF excimer laser, EB or EUV, particularly EB or EUV.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
In addition, the following Examples 1-2 are Reference Examples 1-2.

In the following Examples 1-10 and Comparative Examples 1-14, the high molecular compound (1) synthesize | combined by copolymerizing the following monomers (1) and (2) by the well-known drop polymerization method was used.
That is, PGMEA was placed in a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring. Next, a monomer PGMEA solution charged with 2,2′-azobisisobutyronitrile (AIBN) and monomer (1) / monomer (2) = 7/3 (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 added dropwise to about 30 times amount of methanol with stirring to obtain a colorless precipitate. The resulting precipitate was filtered off, and the precipitate was washed in about 30 times the amount of methanol used for the monomer used for the polymerization. Then, this precipitate was filtered off and dissolved in THF, and then an 80% by mass hydrazine aqueous solution was added dropwise to the solution, followed by stirring at 25 ° C. for 1 hour. After completion of the reaction, the mixture was dropped into a large amount of water to obtain a precipitate. The precipitate was separated by filtration, washed, and dried under reduced pressure at 50 ° C. for about 40 hours to obtain a polymer compound (1). The said high molecular compound (1) is shown below. In addition, the ratio (p1: q1, molar ratio) of each structural unit, a mass average molecular weight (Mw), and dispersity (Mw / Mn) are written together.

[Examples 1 to 10, Comparative Examples 1 to 14]
The positive resist composition was prepared by mixing and dissolving the components shown in Tables 1 and 2.

In Tables 1 and 2, the values in [] indicate the amount (parts by mass). The symbols in Table 1 and Table 2 indicate the following.
(A) -1: the polymer compound (1).
(B) -1: Triphenylsulfonium nonafluoro-n-butanesulfonate.
(G) -1: The following compound (g1-1): 1,3-benzodioxole.
(G) -2: the following compound (I): 2,6-dimethylphenol.
(G) -3: The following compound (II): pentafluorophenol.
(G) -4: The following compound (g1-4): 2,2-dimethyl-1,3-benzodioxole.
(G) -5: the following compound (III): 1,4-benzodioxane.
(G) -6: The following compound (IV): 2,3-dihydrobenzofuran.
(G) -7: The following compound (g1-5): 3,4- (methylenedioxy) toluene.
(D) -1: tri-n-octylamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

Using the obtained resist composition, a resist pattern was formed by the following procedure, and the lithography characteristics were evaluated.
[Formation of resist pattern]
The positive resist composition obtained above was uniformly applied on an 8-inch silicon substrate having a hexamethylsilazane (HMDS) treatment on the surface, and a pre-bake treatment was performed at 110 ° C. for 60 seconds to obtain a film thickness. A 100 nm resist film 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), post-exposure heat treatment at 100 ° C. for 60 seconds, and 2 at 23 ° C. Developed with a 38% by weight TMAH aqueous solution for 60 seconds, rinsed with pure water for 15 seconds, shaken and dried to form a 100 nm line and space (1: 1) resist pattern (hereinafter referred to as L / S). Pattern).
[Sensitivity (optimum exposure: Eop)]
At this time, the optimum exposure dose Eop (μC / cm ² ) for forming an L / S pattern having a line width of 100 nm and a pitch of 200 nm was determined. The results are shown in Tables 1 and 2.
[Resolution]
The limiting resolution in the Eop was observed with a side length SEM (manufactured by Hitachi, Ltd., trade name: S-9220). The results are shown in Tables 1 and 2.
[LWR (line width roughness) evaluation]
In the L / S pattern having a line width of 100 nm and a pitch of 200 nm formed by the Eop, the line width was determined by a length measurement SEM (scanning electron microscope, acceleration voltage 800 V, product name: S-9220, manufactured by Hitachi, Ltd.) Five points were measured in the longitudinal direction of the line, and from the result, a value (3s) that was three times the standard deviation (s) was calculated as a measure of LWR. The results are shown in Tables 1 and 2. The smaller the value of 3s, the smaller the roughness of the line width, which means that a more uniform width L / S pattern was obtained. The results are shown in Tables 1 and 2.

As is clear from the above results, in Examples 1 to 4 according to the present invention, the sensitivity (optimum exposure amount: Eop) is higher than that of Comparative Examples 1 to 8 while maintaining good resolution of the L / S pattern. It has been confirmed that it can be improved. Moreover, it was excellent also in LWR.
Further, in Examples 5 to 10 according to the present invention, it was confirmed that any of the lithography properties of sensitivity, resolution, and LWR can be improved to the same or higher than those of Comparative Examples 9 to 13. . On the other hand, in Comparative Example 14, the resist pattern was not resolved.

Claims (6)

A positive type containing a base component (A) whose solubility in an alkaline developer is increased by the action of an acid, an acid generator component (B) which generates an acid upon exposure, and benzodioxole or its derivative (G) A resist composition comprising:
(G) includes benzodioxole represented by the following general formula (g1) or a derivative thereof (G1),
A positive resist composition in which the content of (G1) is in the range of 50 to 150 parts by mass with respect to 100 parts by mass of the base material component (A) .

[Wherein, R ¹¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent ; R ¹¹ ′ is a carbon atom having 1 to 1 carbon atoms which may have a hydrogen atom or a substituent ; R ¹¹ and R ¹¹ ′ may be bonded to each other to form a ring; R ^{12 to} R ¹⁴ and R ^{14 ′} each independently have a hydrogen atom or a substituent. The hydrocarbon group having 1 to 30 carbon atoms which may be bonded to each other to form a ring. ] Wherein the base component (A) includes a structural unit derived from hydroxystyrene (a1), characterized by containing the structural unit containing an acid dissociable, dissolution inhibiting group (a2), according to claim 1 A positive resist composition. The structural unit (a1) is represented by the following general formula (a-1)

[In Formula (a-1), R is a hydrogen 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; Is an integer. ]
The positive resist composition according to claim 2, wherein the positive resist composition is a structural unit represented by: The structural unit (a2) is represented by the following general formula (a2-1) or general formula (a2-2):

[In Formula (a2-1), R is a hydrogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹ and R ² are each independently a hydrogen atom or a lower alkyl group; Y ¹ is a lower alkyl group; A group or a monovalent aliphatic cyclic group; n ₂₁ is an integer of 0 to 3. In formula (a2-2), R is as defined above; R ³ and R ⁴ are each independently a hydrogen atom or a lower alkyl group; 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. ]
The positive resist composition according to claim 2 , wherein the positive resist composition is a structural unit represented by: Furthermore, the positive resist composition as described in any one of Claims 1-4 containing a nitrogen-containing organic compound component (D). A step of forming a resist film using the positive resist composition according to any one of claims 1 to 5 , a step of exposing the resist film, and an alkali development of the resist film on a support. A resist pattern forming method including a step of forming a resist pattern.