JP4975382B2 - COMPOUND, POLYMER COMPOUND, POSITIVE RESIST COMPOSITION AND METHOD FOR FORMING RESIST PATTERN - Google Patents

Description

  The present invention relates to a novel compound, a polymer compound, a positive resist composition containing the polymer compound, and a resist pattern forming method using the positive 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.
Along with the miniaturization of semiconductor elements, the wavelength of an exposure light source has been shortened and the projection lens has a high numerical aperture (high NA). Currently, an exposure of NA = 0.84 using an ArF excimer laser having a wavelength of 193 nm as a light source A machine has been developed. Along with the shortening of the wavelength of the exposure light source, the resist material is required to be improved in lithography characteristics such as sensitivity to the exposure light source and resolution capable of reproducing a pattern with a fine dimension. As a resist material satisfying such requirements, a chemically amplified resist containing a base resin whose alkali solubility is changed by the action of an acid and an acid generator that generates an acid upon exposure is used.
Currently, as a base resin of a chemically amplified resist used in ArF excimer laser lithography and the like, a resin having a structural unit derived from (meth) acrylic acid ester in the main chain because of its excellent transparency near 193 nm ( Acrylic resin) is generally used. 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 one of the methods for further improving the resolution, exposure (immersion exposure) is performed by interposing a liquid (immersion medium) having a higher refractive index than air between the objective lens of the exposure machine and the sample. A so-called immersion lithography (hereinafter referred to as “immersion exposure”) is known (for example, see Non-Patent Document 1).
According to immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the depth of focus can be reduced. It is said that there is no decline. Moreover, immersion exposure can be performed using an existing exposure apparatus. For this reason, immersion exposure is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Immersion exposure is effective in forming all pattern shapes, and can be combined with super-resolution techniques such as the phase shift method and the modified illumination method that are currently being studied. Currently, as an immersion exposure technique, a technique mainly using an ArF excimer laser as a light source is being actively researched. Currently, water is mainly studied as an immersion medium.

In recent years, with respect to fluorine-containing compounds, their water repellency, transparency and other characteristics have attracted attention, and research and development in various fields has been actively conducted. For example, in the field of resist materials, acid instability such as a methoxymethyl group, tert-butyl group, tert-butyloxycarbonyl group, etc. is added to a fluorine-containing polymer compound for use as a base resin of a positive chemically amplified resist. Introducing groups. However, when such a fluorine-based polymer compound is used as a base resin of a positive resist composition, there are disadvantages such as generation of a large amount of outgas after exposure and insufficient resistance to dry etching gas (etching resistance).
Recently, a fluorine-containing polymer compound having an acid labile group containing a cyclic hydrocarbon group has been reported as a fluorine-containing polymer compound having excellent etching resistance (see, for example, Non-Patent Document 2).
OPTRONICS N0.4 2003. Proceedings of SPIE-The International Society for Optical Engineering (2002), 4690, 76-83.

In immersion exposure, in addition to normal lithography characteristics (sensitivity, resolution, etching resistance, etc.), a resist material having characteristics corresponding to the immersion exposure technique is required. For example, when the immersion medium is water and the immersion exposure is performed using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium is a lens. Water tracking is required to follow the movement of the water. If the water followability is low, the exposure speed is lowered, and there is a concern that the productivity may be affected. This water followability is considered to be improved by increasing the hydrophobicity (hydrophobing) of the resist film. However, even if the resist film is simply hydrophobized, there is an adverse effect on the lithography properties. There is a tendency that the property and sensitivity decrease, the scum generation amount increases, and the like.
Thus, in immersion exposure, the development of materials having moderate hydrophobicity becomes an important issue. However, there are currently few known materials that satisfy both lithography characteristics and characteristics required for immersion exposure.
The present invention has been made in view of the above circumstances, and includes a novel compound, a polymer compound, a positive resist composition containing the polymer compound, and a resist pattern forming method using the positive resist composition. The purpose is to provide.

  A first aspect of the present invention that solves the above problems is a compound represented by the following general formula (I).

［式中、Ｒ^１は水素原子またはメチル基であり；Ｒ^２，Ｒ^３はそれぞれ独立に水素原子または炭素数１〜５のアルキル基であり；ｎは０〜３の整数であり、Ｚは、置換基としてフッ素原子および／またはフッ素化アルキル基を有する炭素数４〜１２の脂肪族環式基であって、該脂肪族環式基を構成する原子のうち、少なくとも、Ｚに隣接する原子が結合する原子に、フッ素原子またはフッ素化アルキル基が結合している。］

[Wherein, R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; n is an integer of 0 to 3, and Z is , What aliphatic cyclic group der C4-12 having a fluorine atom and / or a fluorinated alkyl group as a substituent, among the atoms constituting the aliphatic cyclic group, at least adjacent to Z A fluorine atom or a fluorinated alkyl group is bonded to the atom to which the atom is bonded . ]

  The second aspect of the present invention is a polymer compound having a structural unit (a1) represented by the following general formula (II).

［式中、Ｒ^１は水素原子またはメチル基であり；Ｒ^２，Ｒ^３はそれぞれ独立に水素原子または炭素数１〜５のアルキル基であり；ｎは０〜３の整数であり、Ｚは、置換基としてフッ素原子および／またはフッ素化アルキル基を有する炭素数４〜１２の脂肪族環式基であって、該脂肪族環式基を構成する原子のうち、少なくとも、Ｚに隣接する原子が結合する原子に、フッ素原子またはフッ素化アルキル基が結合している。］

[Wherein, R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; n is an integer of 0 to 3, and Z is , What aliphatic cyclic group der C4-12 having a fluorine atom and / or a fluorinated alkyl group as a substituent, among the atoms constituting the aliphatic cyclic group, at least adjacent to Z A fluorine atom or a fluorinated alkyl group is bonded to the atom to which the atom is bonded . ]

A third aspect of the present invention is a positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure, The positive resist composition, wherein the resin component (A) contains the polymer compound according to the second aspect of the present invention.
A fourth aspect of the present invention includes a step of forming a resist film on a substrate using the positive resist composition of the third aspect of the present invention, a step of exposing the resist film, and developing the resist film And a resist pattern forming method including a step of forming a resist pattern.

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

  According to the present invention, a novel compound, a polymer compound, a positive resist composition containing the polymer compound, and a resist pattern forming method using the positive resist composition can be provided.

≪Compound≫
The compound of the present invention (hereinafter referred to as compound (I)) is represented by the above general formula (I).
In the formula (I), R ¹ is a hydrogen atom or a methyl group, preferably a methyl group.
R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Specific examples of the alkyl group for R ² and R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Among these, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
In the present invention, it is preferable that at least one of R ^2, R ³ is a hydrogen atom, a one hydrogen atom of R ^2, R ^3, and the other is a hydrogen atom or a methyl group More preferably, it is most preferable that both R ² and R ³ are hydrogen atoms.
n is an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 1.

Z is an aliphatic cyclic group having 4 to 12 carbon atoms having a fluorine atom and / or a fluorinated alkyl group as a substituent.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The term “having a substituent” for the aliphatic cyclic group means that the substituent is directly bonded to the atoms constituting the ring of the aliphatic cyclic group.

In the present invention, the aliphatic cyclic group of Z needs to have at least one or both of a fluorine atom and a fluorinated alkyl group as a substituent, and particularly preferably has a fluorinated alkyl group.
A fluorinated alkyl group is an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms.
The alkyl group not substituted with a fluorine atom is preferably a linear or branched alkyl group, preferably having 1 to 5 carbon atoms, more preferably 1 to 4, more preferably 1 It is more preferable that it is -2, and specifically, the same alkyl group as the alkyl group mentioned as the lower alkyl group for R ² and R ³ described above can be used.
The fluorinated alkyl group is preferably a perfluoroalkyl group in which all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms, more preferably a C 1-5 perfluoroalkyl group, and most preferably a trifluoromethyl group.

  In Z, the aliphatic cyclic group may have a substituent other than a fluorine atom and a fluorinated alkyl group. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an oxygen atom (= O).

1-3 are preferable, as for the number of the substituents which the aliphatic cyclic group of Z has, 1-2 are more preferable, and 1 is the most preferable.
The bonding position of the substituent is not particularly limited. Considering the ease of synthesis, etc., among the atoms constituting the aliphatic cyclic group, at least an atom adjacent to Z (when n is 0, it is an oxygen atom, and when n is 1 to 3, it is a carbon atom) It is preferable that a fluorine atom or a fluorinated alkyl group is bonded to the atom to which is bonded.

In Z, the basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a ring composed of carbon and hydrogen (hydrocarbon ring), but may be a hydrocarbon ring. preferable.
The aliphatic cyclic group may be either saturated or unsaturated, and is usually preferably saturated.
The aliphatic cyclic group for Z may be a monocyclic group or a polycyclic group. In consideration of etching resistance and the like, the aliphatic cyclic group in Z is preferably a polycyclic group.
Specific examples of Z in which the aliphatic cyclic group is a monocyclic group include, for example, a group obtained by removing one hydrogen atom from a monocycloalkane having at least a fluorine atom and / or a fluorinated alkyl group as a substituent. Can be mentioned. Examples of the monocycloalkane include cyclopentane and cyclohexane.
Specific examples of Z in which the aliphatic cyclic group is a polycyclic group include, for example, polycycloalkane (bicycloalkane, tricycloalkane, tetracycloalkane) having at least a fluorine atom and / or a fluorinated alkyl group as a substituent. Etc.) and a group obtained by removing one hydrogen atom. More specifically, examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

  In the present invention, Z is preferably an aliphatic polycyclic group having at least a fluorine atom and / or a fluorinated alkyl group as a substituent in consideration of etching resistance and the like, and at least a fluorine atom and / or as a substituent. A group obtained by removing one hydrogen atom from norbornane having a fluorinated alkyl group is more preferable, and a 2-norbornyl group in which a fluorine atom or a fluorinated alkyl group is bonded to the 2-position is particularly preferable.

  In the present invention, the compound (I) is particularly preferably represented by the following general formula (I-1).

［式中、Ｒ^１は水素原子またはメチル基であり；Ｒ^４はフッ素原子またはフッ素化アルキル基である。］

[Wherein, R ¹ represents a hydrogen atom or a methyl group; R ⁴ represents a fluorine atom or a fluorinated alkyl group. ]

In general formula (I-1), R ² and R ³ in general formula (I) described above are hydrogen atoms, n is 1, and Z is bonded to a fluorine atom or a fluorinated alkyl group at the 2-position. It corresponds to the case of 2-norbornyl group.
R in the formula (I-1) is the same as described above.
R ⁴ is preferably a fluorinated alkyl group, and examples of the fluorinated alkyl group include the same fluorinated alkyl groups as those described above as the substituent for Z.

Compound (I) is, for example, an alcohol compound represented by the formula HO— (CH ₂ ) _n —Z [wherein n and Z are the same as n and Z in formula (I), respectively. ] As a starting material, a chloroalkyl ether compound represented by the formula Cl—C (R ¹ ) (R ² ) —O— (CH ₂ ) _n —Z is synthesized, and the chloroalkyl ether compound and methacrylic acid or acrylic It can be synthesized by reacting with an acid.
The method for synthesizing the chloroalkyl ether compound is not particularly limited, and can be generally performed using a known method. For example, a chloroalkyl ether compound in which R ¹ and R ² are both hydrogen atoms, that is, a chloromethyl ether compound represented by the formula Cl—CH ₂ —O— (CH ₂ ) _n —Z is represented by the following formula: First, an alcohol compound represented by the formula HO— (CH ₂ ) _n —Z and paraformaldehyde are dissolved in an organic solvent, and hydrogen chloride gas (HCl) is blown into the organic solvent, followed by heating (40-100). For example).

［上記式中、ｐはパラホルムアルデヒドの重合度を表す。ｎおよびＺは、式（Ｉ）中のｎおよびＺと同じである。］

[In the above formula, p represents the degree of polymerization of paraformaldehyde. n and Z are the same as n and Z in the formula (I). ]

The compound (I) of the present invention is a novel compound which has not been known so far.
Compound (I) can be suitably used for the production of the polymer compound of the present invention described below.

≪Polymer compound≫
The polymer compound of the present invention (hereinafter sometimes referred to as polymer compound (A1)) has the structural unit (a1) represented by the general formula (II) as an essential structural unit.
The structural unit (a1) is a structural unit formed by cleavage of the ethylenic double bond of the compound (I) of the present invention.
^R 1 in the general formula ^{(II), R 2, R} 3, n, Z , respectively, ^{R 1,} R ^2, R 3 in Formula (I), n, is the same as Z.
In the structural unit (a1), when an acid is generated by exposure from the acid generator component (B) blended with the polymer compound (A1) in the positive resist composition of the present invention described later, the action of the acid causes , The bond between the oxygen atom bonded to the carbonyl group in formula (II) and the carbon atom to which R ² and R ³ are bonded is cleaved, and a terminal moiety containing Z (—C (R ¹ ) (R ² _{) -O- (CH 2) n -Z} ) dissociates. Dissociation of the terminal portion increases the alkali solubility of the entire polymer compound (A1).

In the present invention, the structural unit (a1) is preferably represented by the following general formula (II-1).
^R 1, ^{R 4} in formula (II-1) are respectively the same as ^R 1, ^{R 4} in the general formula (I-1).

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a1) in the polymer compound (A1) is preferably 10 mol% or more, more preferably 10 to 80 mol%, based on the total of all the structural units constituting the polymer compound (A1). 20-60 mol% is more preferable, and 25-50 mol% is the most preferable. By setting it to the lower limit value or more, a pattern can be obtained when a positive resist composition is obtained. Moreover, when it is 80 mol% or less, when it contains another structural unit, the balance with this other structural unit will become favorable, and a lithography characteristic will improve.

<Structural unit (a2)>
In addition to the structural unit (a1), the polymer compound (A1) preferably has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
The “lactone-containing cyclic group” refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
The lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or the hydrophilicity with the developer when the polymer compound (A1) is used for forming a resist film. It is effective in doing.

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

As the structural unit (a2), any unit can be used without any particular limitation.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring.
More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｒ’は水素原子、低級アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数であり、Ａは炭素数１〜５のアルキレン基または酸素原子である。］

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

In general formulas (a2-1) to (a2-5), the halogen atom, lower alkyl group, or halogenated lower alkyl group represented by R may be bonded to the α-position carbon atom of the acrylate ester. The same thing as what was mentioned as a substituent (substituent of (alpha) position) is mentioned.
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1).
Specific examples of the alkylene group having 1 to 5 carbon atoms of A include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group.
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

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

In the polymer compound (A1), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the polymer compound (A1) is preferably from 5 to 80 mol%, more preferably from 10 to 60 mol%, based on the total of all structural units constituting the polymer compound (A1). Preferably, 20 to 60 mol% is more preferable. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

<Structural unit (a3)>
The polymer compound (A1) is derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural unit (a1) and the structural unit (a2). The structural unit (a3) may be included. By including the structural unit (a3), the hydrophilicity of the polymer compound (A1) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. To do.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). . As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. The polycyclic group preferably has 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

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

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

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

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

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

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

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
When the polymer compound (A1) contains the structural unit (a3), the proportion of the structural unit (a3) is 5 to 50 mol% with respect to all the structural units constituting the polymer compound (A1). It is preferably 5 to 40 mol%, more preferably 5 to 25 mol%. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

<Other structural units>
The polymer compound (A1) may contain other structural units other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired. The other structural unit is not particularly limited as long as it is not classified into the structural units (a1) to (a3) described above, and for ArF excimer laser, KrF excimer laser (preferably for ArF excimer laser) A large number of hitherto known materials can be used for these resist resins. Specific examples of the other structural unit include the structural units (a4) and (a1 ′) shown below.

<Structural unit (a4)>
The structural unit (a4) is a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group.
Examples of the polycyclic group include those similar to the polycyclic group among the aliphatic cyclic groups listed in the structural unit (a1). For ArF excimer laser, Many things conventionally known as what is used for the resin component of resist compositions, such as KrF excimer laser (preferably for ArF excimer laser), can be used. In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

  When the structural unit (a4) is contained in the polymer compound (A1), the proportion of the structural unit (a4) is 1 to 30 mol% with respect to the total of all the structural units constituting the polymer compound (A1). Preferably, 10 to 20 mol% is more preferable.

[Structural unit (a1 ′)]
The structural unit (a1 ′) is a structural unit derived from an acrylate ester having an acid dissociable, dissolution inhibiting group, and is a structural unit not corresponding to the structural unit (a1).
As the acid dissociable, dissolution inhibiting group for the structural unit (a1 ′), those proposed so far as the acid dissociable, dissolution inhibiting group for base resins for chemically amplified resists can be used. In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group in (meth) acrylic acid or the like; an acetal-type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group is widely known. .

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.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-amyl group, and a tert-heptyl group. .

In the “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”, the aliphatic cyclic group is the same as those exemplified as the aliphatic cyclic group for Z in the general formula (II). Can be mentioned. The aliphatic cyclic group may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
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 a structural unit represented by the following general formula (a1 ″), an aliphatic cyclic group such as an adamantyl group, such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—); And a group having a branched alkylene group having a tertiary carbon atom bonded thereto.

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

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

The “acetal-type acid dissociable, dissolution inhibiting group” is generally bonded to an oxygen atom by substituting a hydrogen atom at the terminal of an alkali-soluble group such as a carboxy group or a hydroxyl group. When an acid is generated by exposure, 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, at least one of R ^{1 ′} and R ^{2 ′} is preferably 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” What was mentioned as an aliphatic cyclic group in the "acid dissociable, dissolution inhibiting group containing a formula group" (however, it has a fluorine atom as a substituent, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom) Can be used as an example).

  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. It is particularly 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.

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

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

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

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

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

In general formula (a1-0-1), R is the same as defined above.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include the above-described tertiary alkyl ester type acid dissociable, dissolution inhibiting group and acetal type acid dissociable, dissolution inhibiting group. A tertiary alkyl ester type acid dissociable, dissolution inhibiting group is preferred.

In general formula (a1-0-2), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-0-1).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group, and the aliphatic cyclic group is the above except that a group in which two or more hydrogen atoms are removed is used. The thing similar to description of an "aliphatic cyclic group" can be used.

  More specifically, examples of the structural unit (a1 ′) include structural units represented by the following general formulas (a1-1) to (a1-4). Among these, the general formula (a1-1) The structural unit represented is preferred.

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

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

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

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

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

  As the structural unit (a1 ′), in particular, a structure represented by the following general formula (a1-1-01) including the structural units of the above formulas (a1-1-1) to (a1-1-4). The structural unit represented by the following general formula (a1-1-02) including the units and structural units of the formulas (a1-1-35) to (a1-1-41) is preferable, and among them, the general formula (a1 The structural unit represented by (1-1-01) is preferable.

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

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

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

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

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

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

In the polymer compound (A1), as the structural unit (a1 ′), one type of structural unit may be used, or two or more types may be used in combination.
When the polymer compound (A1) contains the structural unit (a1 ′), the proportion of the structural unit (a1 ′) in the polymer compound (A1) is the sum of all the structural units constituting the polymer compound (A1). On the other hand, 1-50 mol% is preferable, 5-50 mol% is more preferable, and 10-40 mol% is further more preferable. By setting it to the lower limit value or more, a pattern can be easily obtained when the positive resist composition is obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

In the present invention, the polymer compound (A1) is preferably a copolymer having at least two types of structural units (a1) and (a2). Examples of the copolymer include a binary copolymer composed of the structural units (a1) and (a2), and a ternary copolymer composed of the structural units (a1), (a2) and (a3). Examples thereof include quaternary copolymers comprising units (a1), (a2), (a3) and (a4).
In the present invention, the polymer compound (A1) is particularly preferably a copolymer containing two types of structural units in the combination represented by the following general formula (A-11).

［式（Ａ１−１１）中、Ｒ^１、Ｒ^４およびＲは上記と同様である。］

[In formula (A1-11), R ¹ , R ⁴ and R are the same as defined above. ]

The polymer compound (A1) 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). it can.
Further, in the polymer compound (A1), a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination in the above polymerization. it may be introduced -C _{(CF 3)} 2 -OH group at the terminal. As described above, a resin having a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective for.

Although the mass mean molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of a high molecular compound (A1) is not specifically limited, 2000-50000 are preferable, 3000-30000 are more preferable, 5000-20000 are preferable. Is most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Moreover, 1.0-5.0 are preferable and, as for the dispersity (Mw / Mn) of a high molecular compound (A1), 1.0-3.0 are more preferable. Mn represents a number average molecular weight.

The polymer compound (A1) of the present invention is a novel compound not conventionally known.
The polymer compound (A1) is useful as a base resin for a chemically amplified positive resist composition, and can be suitably used as the component (A) in the positive resist composition of the present invention described below.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter referred to as “component (A)”) and an acid generator component (B) which generates an acid upon exposure ( (Hereinafter referred to as component (B)).
In such a positive resist composition, when radiation is irradiated (exposed), an acid is generated from the component (B), and the alkali solubility of the component (A) is increased by the action of the acid. Therefore, in the formation of a resist pattern, when selective exposure is performed on a resist film obtained using the positive resist composition, the alkali solubility of the exposed portion increases while the unexposed portion remains alkali-insoluble. Since it does not change, a resist pattern can be formed by performing alkali development.

<(A) component>
(A) A component contains the high molecular compound (A1) of this invention mentioned above.
In the polymer compound (A1), when an acid is generated from the component (B), due to the action of the acid, —C (R ¹ ) (R ² ) —O— (CH ₂ ) _n — Z dissociates. —C (R ¹ ) (R ² ) —O— (CH ₂ ) _n —Z has a function as a dissolution inhibiting group that suppresses alkali solubility of the polymer compound (A1), and this dissolution inhibition Dissociation of the group increases the alkali solubility of the polymer compound (A1).
In the component (A), the polymer compound (A1) may be used alone or in combination of two or more.
The proportion of the polymer compound (A1) in the component (A) is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and 100% by mass with respect to the total mass of the component (A). Good.

The component (A) contains “resin whose alkali solubility is increased by the action of an acid” (hereinafter referred to as resin (A2)) other than the polymer compound (A1) as long as the effects of the present invention are not impaired. May be.
The resin (A2) is not particularly limited, and many resins conventionally known as base resins for chemically amplified positive resist compositions, for example, for ArF excimer laser, for KrF excimer laser (preferably ArF) Any base resin such as for excimer laser) may be selected and used.
Resin (A2) may be used individually by 1 type, and may be used in combination of 2 or more type.

<(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, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Examples of the onium salt acid generator include an acid generator represented by the following general formula (b-0).

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

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

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

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

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

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

  Examples of other onium salt acid generators represented by the general formula (b-0) include compounds represented by the following general formula (b-1) or (b-2). .

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

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

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

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. It is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

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) phenylsulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate. In addition, onium salts in which the anion portion of these onium salts is replaced with methanesulfonate, n-propanesulfonate, n-butanesulfonate, or n-octanesulfonate can also be used.

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

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

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

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

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.

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

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

(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, among the above, it is preferable to use, as the component (B), an onium salt acid generator and / or a diazomethane acid generator having a fluorinated alkyl sulfonate ion as an anion.
0.5-30 mass parts is preferable with respect to 100 mass parts of (A) component, and, as for content of (B) component in the positive resist composition of this invention, 1-10 mass parts is more preferable. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<Optional component>
The positive resist composition of the present invention further contains a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component in order to improve the resist pattern shape, stability over time, etc. It is preferable to do.
Since a wide variety of components (D) have already been proposed, any known one may be used. Cyclic amines, aliphatic amines, particularly secondary aliphatic amines and tertiary fats may be used. Group amines are preferred. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include 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, alkyl alcohol amines and / or trialkyl amines are preferable, and alkyl alcohol amines are most preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

The positive resist composition of the present invention includes, as optional components, organic carboxylic acids, phosphorus oxoacids and derivatives thereof for the purpose of preventing sensitivity deterioration, improving the resist pattern shape, retention stability over time, etc. At least one compound (E) selected from the group consisting of (hereinafter referred to as component (E)) can be contained.
Examples of the organic carboxylic acid include acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid. Among these, salicylic acid is particularly preferable.
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.
These may be used alone or in combination of two or more.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

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

<Organic solvent>
The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or 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;
Examples include aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene. 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 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. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 3-15% by mass.

The positive resist composition of the present invention is a novel one that has not been known so far.
In addition, since the structural unit (a1) contains a fluorine atom in the positive resist composition of the present invention, the resist film formed using the positive resist composition as compared with the case where no fluorine atom is contained. Is highly hydrophobic. Therefore, it is suitable for immersion exposure described later.
The positive resist composition of the present invention also has good lithography properties such as sensitivity, resolution, and etching resistance. For example, by using the positive resist composition of the present invention, a fine resist pattern having a line width of a line and space (L / S) pattern of 120 nm or less can be formed. Further, since the positive resist composition of the present invention has an aliphatic cyclic group, it has excellent etching resistance, and the etching resistance is particularly high when the aliphatic cyclic group in Z in formula (II) is polycyclic. It is particularly good when it is a formula group.
Further, according to the positive resist composition of the present invention, a resist pattern can be satisfactorily formed even when an acid generator having a weak acid strength is used. That is, in the conventional positive resist composition, when an acid generator having a weak acid strength is used, the acid dissociable, dissolution inhibiting group is not sufficiently dissociated and the resist pattern is not sufficiently resolved. In some cases, the type of acid generator that can be used is limited. Therefore, at present, as an acid generator, an onium salt acid generator having a strong fluorinated alkyl sulfonate ion in the anion portion and having a strong acid strength is most commonly used. In the present invention, compared to the onium salt acid generator, an acid generator having a relatively weak acid strength (for example, a nonionic acid such as a diazomethane acid generator or an oxime sulfonate acid generator). Since the resist pattern can be formed using (generator), the type of component (B) is not limited, and any one of many acid generators proposed so far can be selected. Can be used. Therefore, the positive resist composition of the present invention can be used in a wide range of applications in the lithography field.

The positive resist composition of the present invention has various excellent properties as described above. In particular, the formed resist film has high hydrophobicity, and even when a nonionic acid generator is used. From the viewpoint that a resist pattern can be formed, it is suitable for immersion exposure.
As described above, in immersion exposure, during exposure, a portion between a lens, which is conventionally filled with an inert gas such as air or nitrogen, and a resist film on the wafer is refracted larger than the refractive index of air. It is the method which has the process of performing exposure (immersion exposure) in the state satisfy | filled with the solvent (immersion medium) which has a rate.
In immersion exposure, when the resist film and the immersion solvent come into contact with each other, elution (substance elution) of substances ((B) component, (D) component, etc.) in the resist film into the immersion solvent occurs. Substance elution causes phenomena such as alteration of the resist layer and change in the refractive index of the immersion solvent, thereby deteriorating the lithography properties. The amount of this substance elution is affected by the characteristics of the resist film surface (for example, hydrophilicity / hydrophobicity). Therefore, for example, it is presumed that elution of the substance is reduced by increasing the hydrophobicity of the resist film surface.
The resist film formed using the positive resist composition of the present invention has a resist film that contains a fluorine atom in the structural unit (a1), as compared with the case where a conventional positive resist composition is used. The contact angle with water, for example, the static contact angle (the angle between the water droplet surface on the horizontal resist film and the resist film surface), the dynamic contact angle (when the resist film is inclined) The contact angle when the water droplet starts to fall in. There are the contact angle (advance angle) at the end point in front of the water drop direction and the contact angle (retreat angle) at the end point in the rear direction of the drop.) When the film is inclined, the inclination angle of the resist film when the water droplet starts to fall changes). For example, the higher the hydrophobicity of the resist film, the larger the static contact angle and dynamic contact angle, while the smaller the falling angle.
Therefore, according to the positive resist composition of the present invention, substance elution during immersion exposure can be suppressed.

Here, as shown in FIG. 1, when the plane 2 on which the droplet 1 is placed is gradually inclined, the advance angle starts to move (drop) on the plane 2 when the droplet 1 is gradually inclined. Is the angle θ ₁ formed by the surface of the droplet at the lower end 1 a of the droplet 1 and the plane 2. At this time (when the droplet 1 starts moving (falling) on the plane 2), the angle θ2 formed by the droplet surface at the upper end 1b of the droplet 1 and the plane ₂ is the receding angle, The inclination angle θ _{3 of the} plane 2 is the falling angle.

In this specification, the static contact angle, the dynamic contact angle, and the sliding angle are measured as follows.
First, a resist composition solution is spin-coated on a silicon substrate, and then heated at 90 ° C. for 90 seconds to form a resist film.
Next, DROP MASTER-700 (manufactured by Kyowa Interface Science Co., Ltd.), AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.) It can measure using commercially available measuring apparatuses, such as.

  Furthermore, in the present invention, as described above, a resist pattern can be formed even when a nonionic acid generator is used. Nonionic acids are less likely to elute from the resist film than ionic acids. Therefore, when the component (B) is a nonionic acid generator (such as a diazomethane acid generator or an oxime sulfonate acid generator), the amount of substance elution is further reduced.

As described above, in the present invention, substance elution into the immersion solvent is suppressed. Therefore, by using the positive resist composition of the present invention in immersion exposure, it is possible to suppress the alteration of the resist film and the change in the refractive index of the immersion solvent. Therefore, the shape of the resist pattern to be formed is improved, for example, by suppressing fluctuations in the refractive index of the immersion solvent.
In addition, contamination of the lens of the exposure apparatus can be reduced, and therefore protection measures for these can be omitted, contributing to simplification of the process and the exposure apparatus.
Further, as described above, when performing immersion exposure using a scanning immersion exposure machine as described in Non-Patent Document 1, the immersion medium moves following the movement of the lens. Although followability is required, in the present invention, the resist film has high hydrophobicity and high water followability. Moreover, the positive resist composition of the present invention has good lithography characteristics, and can be used to form a resist pattern without any practical problems when used as a resist in immersion exposure.
As described above, the positive resist composition of the present invention has good lithography characteristics (sensitivity, resolution, etching resistance, etc.) that are usually required, and characteristics (hydrophobic properties) that are required for resist materials in immersion exposure. Property, substance elution suppression ability, water followability, etc.). Therefore, the positive resist composition of the present invention is suitable for immersion exposure.

≪Resist pattern formation method≫
Next, the resist pattern forming method of the present invention will be described.
The method for forming a resist pattern according to this aspect includes a step of forming a resist film on a substrate using the resist composition of the present invention, a step of exposing the resist film, and developing the resist film to form a resist pattern. Process.
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the resist composition of the present invention is applied onto a substrate such as a silicon wafer with a spinner or the like, and pre-baking (post-apply baking (PAB)) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds. Preferably, it is applied for 60 to 90 seconds to form a resist film. The resist film is selectively exposed using a predetermined exposure light source with or without a desired mask pattern. That is, exposure is performed through the mask pattern, or drawing is performed by direct irradiation with an electron beam without using the mask pattern.
After the selective exposure, heat treatment (post-exposure baking (PEB)) is performed for 40 to 120 seconds, preferably 60 to 90 seconds, at a temperature of 80 to 150 ° C. Subsequently, a resist pattern can be formed by developing this using an alkali developing solution, for example, 0.1-10 mass% tetramethylammonium hydroxide (TMAH) aqueous solution.
An organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.
The wavelength used for exposure is not particularly limited, and includes KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. Among these, the resist composition of the present invention is particularly effective for ArF excimer laser.

<Immersion exposure>
As described above, the positive resist composition of the present invention can be suitably used for immersion exposure.
In the immersion exposure, the resist pattern can be formed by performing exposure by immersion exposure, that is, performing a step of immersion exposure of the resist film in the step of exposing the resist film in the resist pattern forming method.
The step of immersing and exposing the resist film can be performed, for example, as follows.
First, the space between the resist film obtained as described above and the lens at the lowest position of the exposure apparatus is filled with a solvent (immersion medium) having a refractive index larger than the refractive index of air. Exposure (immersion exposure) is performed with or without a mask pattern.
The wavelength used for exposure is not particularly limited, and the same ones as mentioned above can be used.

As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film formed using the positive resist composition of the present invention is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, and a silicon-based solvent.
Specific examples of the fluorine-based inert _liquid, mainly composed of _{C 3 HC l2 F 5, C} 4 F 9 OCH 3, C 4 F 9 OC 2 H 5, C 5 H 3 F 7 , etc. A fluorine- Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).

  Since the positive resist composition of the present invention is not particularly adversely affected by water and is excellent in sensitivity and resist pattern shape, water is preferably used as a solvent having a refractive index larger than that of air. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
Example 1
[1-1: Synthesis of Compound 1]
2-trifluoromethyl-2-hydroxymethylnorbornane was added to paraformaldehyde, and 2.5 equivalents of hydrogen chloride gas was blown into 2-trifluoromethyl-2-hydroxymethylnorbornane and reacted at 50 ° C. After completion of the reaction, the product was distilled under reduced pressure to obtain Compound 1 [2- (chloromethoxymethyl) -2-trifluoromethylnorbornane] having the structure shown below.

[1-2: Synthesis of Compound 2]
3.9 g of methacrylic acid was dissolved in 50 mL of tetrahydrofuran and 5.0 g of triethylamine was added. After stirring this solution at room temperature, 50 mL of tetrahydrofuran in which 10.0 g of Compound 1 was dissolved was dropped into the solution. After stirring this at room temperature for 12 hours, the deposited salt was filtered off. The obtained filtrate was evaporated, dissolved in 100 mL of ethyl acetate, washed with pure (50 mL × 3 times), evaporated to remove compound 2 [2-methyl (2-trifluoromethylnorbornyl). Nyl) oxymethyl methacrylate] was obtained.
Compound 2 was subjected to infrared absorption spectrum (IR) measurement, proton nuclear magnetic resonance spectrum ( ¹ H-NMR) measurement, and elemental analysis. The results are shown below.
In the following ¹ H-NMR and ¹³ C-NMR results, the hydrogen atom (H) or carbon atom (C) indicated by the numerical value was underlined.
IR (cm ⁻¹ ): 2991, 2911, 2854 (νC—H), 1712 (νC═O, ester), 1638 (νC = C, vinyl), 1172, 1098 (νC—O, ester), 931 (νO) -CO, ether).
¹ H-NMR (400 MHz, CDCl ₃ , TMS): δ 0.80-1.75 (8H, m, 3-H ₂ , 5-H ₂ , 6-H ₂ , 7-H ₂ norbornyl), 1.55 _{(3H, s, CH 2 =} C (C H 3) -), 2.20 (1H, m, 1H norbornyl), 2.45 (1H, m, 4-H norbornyl), 3.49-3 .80 (2H, m, —O—C H ₂ —norbornyl), 5.28-5.30 (2H, m, —COOC H ₂ —O—), 5.50 (1H, s, C H ₂ = _{C (CH 3) -),} 6.05 (1H, s, C H 2 = C (CH 3) -).
_{^{13 C-NMR (400MHz, CDCl}} 3, TMS): δ18.7 (CH 3), 51.3 (quaternary, 2-C norbornyl), 72.3 (-O- C H 2 -norbornyl), 90.2 (COO C H ₂ O), 126.8 (CH ₂ =), 126.9, 127.8, 128.9, 130.8 (CF ₃ ), 137.0 (= C (CH ₃ )-), 167.3 (carbonyl).
Calcd _{C 14 H 19 F 3 O 3} (292.13): C, 57.53%; H, 6.55%; F, 19.50%; O, 16.42%. Found: C, 57.28%; H, 6.52%; F, 18.64%.
From the above results, it was confirmed that the compound 2 had the structure shown below.

Example 2 [Synthesis of Resin 1]
8.5 g of Compound 2 and 4.4 g of γ-butyrolactone methacrylate were dissolved in 50 mL of tetrahydrofuran, and 0.21 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the solution was dropped into methanol, and the precipitated resin was filtered twice and dried under reduced pressure to obtain a white powder resin. This resin is referred to as Resin 1.
The structural formula of Resin 1 is shown below. Resin 1 had a molecular weight (Mw) of 11000 and a dispersity (Mw / Mn) of 1.55. Moreover, as a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio [ratio of m1 and n1 in the following structural formula] was m1: n2 = 0.42: 0.58 (molar ratio). )Met. Moreover, Tg (glass transition point) was 125 degreeC and Td (thermal decomposition point) was 240 degreeC. Tg was measured with a thermal analyzer TG / DTA6200 (manufactured by Seiko Instrument) under a temperature rising condition of 10 ° C./min. Td was measured with a thermal analyzer DSC6200 (manufactured by Seiko Instrument) under a temperature rising condition of 10 ° C./min.

<Contact angle measurement>
On a silicon substrate, a resin solution in which 100 parts by mass of resin 1 is dissolved in 1550 parts by mass of ethyl lactate is applied by spin coating, and a baking process is performed at 100 ° C. for 60 seconds. A film thickness of 150 nm) was produced.
Water (2 μL: static contact angle measurement, 50 μL: dynamic contact angle measurement) was dropped on the surface of the thin film, and contact angle measurement was performed using DROP MASTER-700 manufactured by Kyowa Interface Science Co., Ltd. The obtained results are shown in Table 1.

Comparative Example 1
Implemented except that instead of Resin 1, Comparative Resin 1 represented by the following structural formula (Mw = 9700, Mw / Mn = 1.62, m2: n2 = 0.46: 0.54 (molar ratio)) was used. The contact angle was measured in the same manner as in Example 2. The obtained results are shown in Table 1.

Examples 3-4, Comparative Example 2
Each component shown in Table 2 was mixed and dissolved to prepare a positive resist composition.

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

<Resolution and sensitivity>
About the obtained positive resist composition, the resist pattern was formed in the following procedures, respectively, and resolution and sensitivity were evaluated.
An organic antireflection film composition “ARC-29A” (trade name, manufactured by Brewer Science Co., Ltd.) is applied onto an 8-inch silicon wafer using a spinner, and baked on a hot plate at 205 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a thickness of 77 nm was formed. On the antireflection film, a positive resist composition is applied using a spinner, prebaked (PAB) at 100 ° C. for 60 seconds on a hot plate, and dried to form a film shown in Table 3 A thick resist film was formed.
Next, an ArF excimer laser (193 nm) is selectively passed through a mask pattern by an ArF exposure apparatus NSR-S-302 (manufactured by Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). Irradiated.
Then, PEB treatment was performed at 100 ° C. for 60 seconds, and further developed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution at 23 ° C. for 30 seconds.
As a result, in any example using any positive resist composition, a line-and-space resist pattern (hereinafter referred to as LS pattern) having a line width of 120 nm and a pitch of 240 nm was formed.
Further, at this time, the optimum exposure amount (Eop) (unit: mJ / cm ² (energy amount per unit area)) at which an LS pattern having a line width of 120 nm and a pitch of 240 nm is formed, that is, sensitivity was obtained. As a result, as shown in Table 3, Eop was almost equal in any of Examples 3 to 4 and Comparative Example 2.

As shown in the above results, the resin 1 obtained using the compound 2 of the present invention has a larger static contact angle, advancing angle, and receding angle with respect to the water of the formed film than the comparative resin 1, and falls. The corner was small. From this result, it was confirmed that the film obtained using the resin 1 was a more hydrophobic film than the film obtained using the comparative resin 1.
Further, the positive resist compositions of Examples 3 to 4 containing the resin 1 have the same lithography characteristics (sensitivity, resolution, etc.) as the positive resist composition of the comparative example 2 using the comparative resin 1. Was.
Furthermore, although (B) -1 used in Example 3 is weaker in strength of the acid generated than (B) -2, which is an onium salt acid generator, in the present invention, as (B) component A resist pattern could be formed even using an acid generator that generates such a weak acid.

It is a figure explaining advancing angle ((theta) ₁ ), receding angle ((theta) ₂ ), and falling angle ((theta) ₃ ).

Claims (8)

The compound represented by the following general formula (I).

[Wherein, R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; n is an integer of 0 to 3, and Z is , What aliphatic cyclic group der C4-12 having a fluorine atom and / or a fluorinated alkyl group as a substituent, among the atoms constituting the aliphatic cyclic group, at least adjacent to Z A fluorine atom or a fluorinated alkyl group is bonded to the atom to which the atom is bonded . ] The compound of Claim 1 represented by the following general formula (I-1).

[Wherein, R ¹ represents a hydrogen atom or a methyl group; R ⁴ represents a fluorine atom or a fluorinated alkyl group. ] The high molecular compound which has the structural unit (a1) represented by the following general formula (II).

[Wherein, R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; n is an integer of 0 to 3, and Z is , What aliphatic cyclic group der C4-12 having a fluorine atom and / or a fluorinated alkyl group as a substituent, among the atoms constituting the aliphatic cyclic group, at least adjacent to Z A fluorine atom or a fluorinated alkyl group is bonded to the atom to which the atom is bonded . ] The polymer compound according to claim 3, wherein the structural unit (a1) is represented by the following general formula (II-1).

[Wherein, R ¹ represents a hydrogen atom or a methyl group; R ⁴ represents a fluorine atom or a fluorinated alkyl group. ]   Furthermore, the high molecular compound of Claim 3 or 4 which has a structural unit (a2) induced | guided | derived from the acrylate ester containing a lactone containing cyclic group. A positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure,
The said resin component (A) contains the high molecular compound as described in any one of Claims 3-5, The positive resist composition characterized by the above-mentioned.   The positive resist composition according to claim 6, further comprising a nitrogen-containing organic compound (D).   A resist comprising a step of forming a resist film on a substrate using the positive resist composition according to claim 6, a step of exposing the resist film, and a step of developing the resist film to form a resist pattern. Pattern forming method.

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