JP2008116496A - Positive resist composition and method for formation of resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition and a method for formation of a resist pattern using the positive resist composition. <P>SOLUTION: The positive resist composition comprises a resin component (A) whose alkali solubility can be increased by the action of an acid and an acid generator component (B) which can generate an acid upon being exposed to light, wherein the resin component (A) comprises a copolymer having a constituent unit (a1) represented by general formula (II), wherein R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; and R<SP>1</SP>-R<SP>3</SP>independently represent an alkyl group or a fluorinated alkyl group, provided that, in the fluorinated alkyl group, no fluorine atom is attached to a carbon atom adjacent to a tertiary carbon atom to which R<SP>1</SP>-R<SP>3</SP>are bonded, at least one of R<SP>1</SP>-R<SP>3</SP>represents the fluorinated alkyl group, and R<SP>2</SP>and R<SP>3</SP>may together form a ring structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

In lithography technology, for example, a resist film made of a resist material is formed on a substrate, and the resist film is selectively exposed to radiation such as light or an electron beam through a mask on which a predetermined pattern is formed. And a development process is performed to form a resist pattern having a predetermined shape on the resist film.
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). 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 for a chemically amplified resist used in ArF excimer laser lithography and the like, a resin having a structural unit derived from a (meth) acrylate 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).
Proceedings of SPIE, 5754, 119-128 (2005). 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. As a specific 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 is affected. This water followability is considered to be improved by increasing the hydrophobicity of the resist film (hydrophobizing). On the other hand, 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 an object thereof is to provide a positive resist composition and a resist pattern forming method using the positive resist composition.

  A first aspect of the present invention that solves the above-mentioned problems includes a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) that generates an acid upon exposure, and the resin component (A) is a positive resist composition comprising a copolymer having a structural unit (a1) represented by the following general formula (II).

［式（ＩＩ）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^１〜Ｒ^３は、それぞれ独立してアルキル基またはフッ素化アルキル基である。ただし、前記フッ素化アルキル基は、Ｒ^１〜Ｒ^３が結合している第三級炭素原子に隣接する炭素原子にはフッ素原子が結合していない基であり、Ｒ^１〜Ｒ^３の少なくとも一つは、前記フッ素化アルキル基である。Ｒ^２およびＲ^３は、一つの環構造を形成していてもよい。］

[In formula (II), R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{1 to} R ³ each independently represents an alkyl group or a fluorinated alkyl group. However, the fluorinated alkyl group is a group in which no fluorine atom is bonded to the carbon atom adjacent to the tertiary carbon atom to which R ^{1 to} R ³ are bonded, and at least one of R ^{1 to} R ³ . One is the fluorinated alkyl group. R ² and R ³ may form one ring structure. ]

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

In the present specification and claims, unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
A “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 (copolymer).
“Exposure” is a concept that includes radiation exposure in general.

  The present invention can provide a positive resist composition and a resist pattern forming method using the positive resist composition.

The positive resist composition of the present invention contains a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure, and the resin component (A) contains And a copolymer having a structural unit (a1) represented by the general formula (II) (hereinafter referred to as polymer compound (A1)).
The polymer compound (A1) is a novel compound which has not been known so far, and a copolymerization reaction is performed using a compound represented by the following general formula (I) (hereinafter referred to as compound (I)) as a monomer unit. Is obtained. Compound (I) is also a novel compound that has not been known so far.
Therefore, first, compound (I) and polymer compound (A1) will be described.

［式（Ｉ）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^１〜Ｒ^３は、それぞれ独立してアルキル基またはフッ素化アルキル基である。ただし、前記フッ素化アルキル基は、Ｒ^１〜Ｒ^３が結合している第三級炭素原子に隣接する炭素原子にはフッ素原子が結合していない基であり、Ｒ^１〜Ｒ^３の少なくとも一つは、前記フッ素化アルキル基である。Ｒ^２およびＲ^３は、一つの環構造を形成していてもよい。］

[In Formula (I), R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{1 to} R ³ each independently represents an alkyl group or a fluorinated alkyl group. However, the fluorinated alkyl group is a group in which no fluorine atom is bonded to the carbon atom adjacent to the tertiary carbon atom to which R ^{1 to} R ³ are bonded, and at least one of R ^{1 to} R ³ . One is the fluorinated alkyl group. R ² and R ³ may form one ring structure. ]

<< Compound (I) >>
Compound (I) is represented by the above general formula (I).
In formula (I), R is a hydrogen atom, a halogen atom, a lower alkyl group or 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.
Specific examples of the lower alkyl group include lower linear chains such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and neopentyl. Or a branched alkyl group.
Examples of the halogenated lower alkyl group include groups in which part or all of the hydrogen atoms of the lower alkyl group have been substituted with the halogen atoms.
Among these, a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorinated lower alkyl group is preferable, and a hydrogen atom or a methyl group is most preferable from the viewpoint of industrial availability.

In formula (I), R ^{1 to} R ³ are each independently an alkyl group or a fluorinated alkyl group.
Here, the alkyl group may be linear, branched or cyclic.
In the case of a straight chain or branched chain, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
In the case of a ring, it is preferably 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Among them, a group obtained by removing one or more hydrogen atoms from adamantane is preferable.

The fluorinated alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group excluding the methyl group are substituted with fluorine atoms. However, it is a group in which no fluorine atom is bonded to the carbon atom adjacent to the tertiary carbon atom to which R ^{1 to} R ³ are bonded. Here, the alkyl group not substituted with a fluorine atom may be linear, branched or cyclic. In the case of straight chain or branched chain, the number of carbon atoms is preferably 2 to 7, more preferably 2 to 5, and particularly preferably n-butyl group. In the case of a ring, the same as those described above for the “alkyl group” can be mentioned. The carbon atom to which the fluorine atom in the fluorinated alkyl group is bonded is preferably separated from the tertiary carbon atom to which R ^{1 to} R ³ are bonded.
Preferred examples of such a fluorinated alkyl group include a 4,4,4-trifluoro-n-butyl group.
In compound (I), at least one of R ^{1 to} R ³ is the fluorinated alkyl group. In the present invention, it is preferable that any one of R ^{1 to} R ³ is the fluorinated alkyl group, and the remaining two are alkyl groups.

In the formula (I), R ² and R ³ may be bonded to each other to form one ring structure. When R ² and R ³ are bonded to each other to form one ring structure, R ² and R ³ are preferably not fluorinated, and in this case, R ¹ is the fluorinated alkyl group. It becomes. Examples of the cyclic alkyl group formed by R ² and R ³ at this time include the same as those described above for the “alkyl group”.

  Among such compounds (I), the most preferable one is exemplified by the following formula (I-1).

  Although the manufacturing method of compound (I) is not specifically limited, As a preferable method, for example, the compound (I-0-1) represented by the following general formula (I-0-1) and the following general formula (I-0-) The method of making it react with the compound (I-0-2) represented by 2) is mentioned.

［式（Ｉ−０−１）中、Ｒは前記一般式（Ｉ）中のＲと同様であり；Ｘはハロゲン原子を表し；式（Ｉ−０−２）中、Ｒ^１〜Ｒ^３は前記一般式（Ｉ）中のＲ^１〜Ｒ^３と同様である。］

[In formula (I-0-1), R is the same as R in formula (I); X represents a halogen atom; and in formula (I-0-2), R ^{1 to} R ³ represent The same as R ^{1 to} R ³ in the general formula (I). ]

In general formula (I-0-1), examples of the halogen atom for X include a bromine atom, a chlorine atom, an iodine atom, and a fluorine atom. Of these, a chlorine atom is preferred because of its excellent reactivity.
Further, in the general formula ^{(I-0-1), R,} R 1 ~R 3 is, ^R in Formula ^(I), similar to R 1 to R ^3.

Although it does not specifically limit as a reaction solvent, The thing which can melt | dissolve the said compound which is a raw material is preferable, Specifically, acetonitrile, acetone, etc. are mentioned.
The reaction is preferably carried out in the presence of a base, and the base at this time is not particularly limited, but preferably has a low nucleophilicity, and examples thereof include triethylamine.
In addition, since the reaction proceeds more smoothly, the reaction is preferably performed in the presence of a catalyst. The catalyst may be a conventionally known catalyst, and preferred examples include 4-dimethylaminopyridine.
In carrying out the reaction, it is preferred that the compound (I-0-2) and preferably a base or a catalyst are mixed in a solvent and the compound (I-0-1) is added dropwise thereto. Compound (I-0-1) may be previously dissolved in a solvent and diluted. The temperature and time at the time of dropping may be appropriately selected according to the raw material used, but the temperature is preferably −10 to 100 ° C., more preferably −5 to 90 ° C., and 0 to 80 ° C. It is particularly preferred. The dropping time is preferably 5 to 90 minutes, more preferably 10 to 60 minutes, and particularly preferably 20 to 40 minutes.
The reaction temperature and time after the addition of compound (I-0-1) may be appropriately selected, but the reaction temperature is preferably the temperature at the time of addition of compound (I-0-1). The reaction time may be appropriately selected according to the raw material used, but it is preferably 0.5 to 15 hours, more preferably 1 to 10 hours, and particularly preferably 1.5 to 8 hours. .

  After completion of the reaction, the compound of the present invention may be taken out by a conventionally known method. For example, the reaction solution is washed with water, a basic aqueous solution, a saline solution or the like as necessary, and the organic layer is concentrated. The product may be crystallized. The concentrated organic layer or the crystallized target product may be purified by silica gel column chromatography or the like.

  As the compound (I-0-2), if there is a commercially available product, it may be used, or a synthetic product may be used. The compound (I-0-2) can be synthesized by applying a conventionally known tertiary alcohol synthesis method. For example, a Grignard reaction or a silane compound having a fluorinated alkyl group and a ketone are reacted. Also good.

  The compound (I) is a novel compound that has not been known so far. And it can use suitably for manufacture of the high molecular compound (A1) demonstrated below.

<< Polymer Compound (A1) >>
<Structural unit (a1)>
The 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).
^R, R ¹ in the general formula ^{(II), R 2, R} 3 are each, ^R in Formula (I), is the same as ^{R 1, R 2, R 3} .
In the structural unit (a1), when an acid is generated by exposure from the acid generator component (B) blended together with the polymer compound of the present invention 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 bonded to R ^{1 to} R ³ is cleaved, and the terminal moiety (—C (R ¹⁾ containing R ^{1 to} R ³ is broken. ) (R ² ) (R ³ )) dissociates. Dissociation of the terminal portion increases the alkali solubility of the entire polymer compound.

  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 a —O—C (O) — structure. The lactone ring is counted as the first ring. When only the lactone ring is present, 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 the thing quoted as a substituent (substituent of alpha position) is mentioned.
Examples of the lower alkyl group for R ′ include the same groups as those described above as the lower alkyl group (lower alkyl group at the α-position) which may be bonded to the α-position carbon atom of the acrylate ester.
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.

  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), etc. A number of hitherto known materials can be used as the resist resin. Specific examples of the other structural unit include the structural units (a1 ′) and (a4) shown below.

[Structural unit (a1 ′)]
The structural unit (a1 ′) is a structural unit derived from an acrylate ester having an acid dissociable, dissolution inhibiting group, and does not correspond 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.
Generally, 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 without 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 preferably an aliphatic cyclic group having 4 to 12 carbon atoms, for example.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The aliphatic cyclic group may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms and an oxygen atom (= O). The phrase “aliphatic cyclic group has a substituent” means that the substituent is directly bonded to the atoms constituting the ring of the aliphatic cyclic group.

The basic ring structure excluding the substituents of the “aliphatic cyclic group” is not limited to a ring composed of carbon and hydrogen (hydrocarbon ring), but is preferably a hydrocarbon ring.
The aliphatic cyclic group may be either saturated or unsaturated, and is usually preferably saturated.
The aliphatic cyclic group may be a monocyclic group or a polycyclic group. In view of etching resistance and the like, a polycyclic group is preferable.
Specific examples of the case where the aliphatic cyclic group is a monocyclic group include a group in which one or more hydrogen atoms have been removed from a monocycloalkane. Examples of the monocycloalkane include cyclopentane and cyclohexane.
Specific examples when the aliphatic cyclic group is a polycyclic group include, for example, a group in which one or more hydrogen atoms have been removed from a polycycloalkane (bicycloalkane, tricycloalkane, tetracycloalkane, etc.). Can be mentioned. More specifically, examples of the polycycloalkane include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
The number of the substituents that the aliphatic cyclic group has is preferably 1 to 3, more preferably 1 to 2, and most preferably 1. The bonding position of the substituent is not particularly limited.

  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 represent a hydrogen atom or a lower alkyl group, n represents an integer of 0 to 3, and Y represents a lower alkyl group or an aliphatic cyclic group. ]

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

Examples of the lower alkyl group for Y include the same lower alkyl groups as those described above for R.
The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in a number of conventional ArF resists. For example, the above “aliphatic ring” Those listed as the aliphatic cyclic group in the “acid-dissociable, dissolution-inhibiting group containing a formula group” (provided that the substituent has a fluorine atom or a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom) Can be used).

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

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

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

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, may be linear or branched, and is preferably an ethyl group or a methyl group, and most preferably a methyl group.
In particular, it is preferable that one of R ¹⁷ and R ¹⁸ is a hydrogen atom and the other is a methyl group.
R ¹⁹ is a linear, branched or cyclic alkyl group, preferably having 1 to 15 carbon atoms, and may be any of linear, branched or cyclic.
When R ¹⁹ is linear or branched, it preferably has 1 to 5 carbon atoms, more preferably an ethyl group or a methyl group, and most preferably an ethyl group.
When R ¹⁹ is cyclic, it preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, one or more polycycloalkanes such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane, which may or may not be substituted with a fluorine atom or a fluorinated alkyl group, are included. Examples include groups excluding hydrogen atoms. 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 4-7 membered ring, and more preferably a 4-6 membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

  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. ]

At least one of R ¹ ′ and R ² ′ is preferably a hydrogen atom, more preferably a hydrogen atom. 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。］

[Wherein, 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］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹² represents a lower alkyl group. 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.

[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 A number of hitherto known materials can be used as resin components of resist compositions such as for KrF excimer laser (preferably for ArF excimer laser). 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。］

[Wherein, R is the same 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.

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 such a copolymer include a binary copolymer composed of the structural units (a1) and (a2), a ternary copolymer composed of the structural units (a1), (a2) and (a3), Examples thereof include quaternary copolymers composed of the structural units (a1), (a2), (a3) and (a4).
In the present invention, the polymer compound (A1) is particularly preferably a copolymer containing three structural units of the combination represented by the following general formula (A-1-1) (wherein R represents the above general formula). (Same as R in (I)).

［式中、Ｒは前記一般式（Ｉ）中のＲと同様である。］

[Wherein, R is the same as R in the general formula (I). ]

  The polymer compound (A1) is a monomer derived from each structural unit such as 2,2′-azobisisobutyronitrile (AIBN) or 2,2′-azobis (2,4-dimethylvaleronitrile). It can manufacture by superposing | polymerizing by the conventionally well-known radical polymerization etc. using such a radical polymerization initiator.

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, and 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) is a novel compound that has not been conventionally known. It is useful as a base resin for a chemically amplified positive resist composition and can be suitably used as the component (A) in a positive resist composition described below.

≪Positive resist composition≫
The polymer compound (A1) includes 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) (hereinafter referred to as “acid generator” which generates an acid upon exposure). It is suitable as the component (A) of the resist composition containing the 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>
In the polymer compound (A1), when an acid is generated from the component (B), —C (R ¹ ) (R ² ) (R ³ ) in the structural unit (a1) is dissociated by the action of the acid. -C (R ¹ ) (R ² ) (R ³ ) has a function as a dissolution inhibiting group that suppresses alkali solubility of the polymer compound (A1), and the dissolution inhibiting group dissociates. The alkali solubility of the polymer compound (A1) is increased.
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) may contain “a resin whose alkali solubility is increased by the action of an acid” other than the polymer compound (A1) as long as the effects of the present invention are not impaired.
Such a resin is not particularly limited, and many conventionally known base resins for chemically amplified positive resist compositions, for example, for ArF excimer laser, for KrF excimer laser (preferably for ArF excimer laser) The base resin such as) may be arbitrarily selected and used.
The “resin whose alkali solubility is increased by the action of an acid” may be used alone or in combination of two or more.

<(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 optionally substituted aryl group; u "Is an integer from 1 to 3.]

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

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

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

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

  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 of R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
The alkoxy group that may be substituted with a hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may 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. 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 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.
As the alkyl group for R ⁵ ″ to R ⁶ ″, the same as the alkyl groups for R ¹ ″ to R ³ ″ can be used.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.
"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 the formulas (b-1) and (b-2) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium. Trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or the same Nonafluorobutanesulfonate, trifluoromethanesulfonate of (4-hydroxynaphthyl) dimethylsulfonium, its heptaful Lopropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of dimethylphenylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of methyldiphenylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, (4-Methylphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate Tri (4-tert-butylphenyl) sulfonium trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, [1- (4-methoxynaphthyl)] diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropanesulfonate Examples thereof include nonafluorobutanesulfonate, di (1-naphthyl) phenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate, and nonafluorobutanesulfonate. 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 ″, the strength of the acid increases as the number of hydrogen atoms substituted with fluorine atoms increases, and high-energy light or electron beam of 200 nm or less The 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 or a fluorinated alkyl group having 1 to 4 carbon atoms which has no substituent.

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

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

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

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

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

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

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

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

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

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) benzyl cyanide, α- (4-nitrobenzenesulfonyloxyimino). Benzyl cyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) benzyl cyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzyl cyanide, α- (benzenesulfonyloxyimino)- 2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- (2-chlorobenzenesulfonyl) Oxyimino) -4-me Xylbenzyl cyanide, α- (benzenesulfonyloxyimino) thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) benzyl cyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxy Phenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α -(Methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctenylacetoni Ril, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) ethylacetonitrile, α- (propylsulfonyloxyimino) ) Propylacetonitrile, α- (cyclohexylsulfonyloxyimino) cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino)- 1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclopentenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (N-Butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino ) Phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonite Le, 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 an onium salt acid generator and / or a diazomethane acid generator having a fluorinated alkyl sulfonate ion as an anion as the component (B).
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 and the like. It is preferable to do.
Since a wide variety of components (D) have already been proposed, any known one may be used, but 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, and the like; 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 the 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, and any one of conventionally known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol A compound having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, or propylene glycol monoacetate, monomethyl ether, monoethyl ether of the polyhydric alcohol or the compound having an ester bond, A monoalkyl ether such as monopropyl ether or monobutyl ether or an ether bond such as monophenyl ether Derivatives of polyhydric alcohols such as propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred among these; cyclic ethers such as dioxane, methyl lactate, lactic acid Esters such as ethyl (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, di Aromatic organic solvents such as benzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene, etc. Can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and ethyl lactate (EL) are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of 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.
Moreover, since the positive resist composition of the present invention contains a fluorine atom in the structural unit (a1), the resist film formed using the positive resist composition as compared with a case where the positive resist composition does not contain a fluorine atom. 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. In addition, the positive resist composition of the present invention is excellent in etching resistance particularly when it has an aliphatic cyclic group, and the etching resistance is when the aliphatic cyclic group is a polycyclic group. Especially good.

The positive resist composition of the present invention has various excellent properties as described above, and is particularly suitable for immersion exposure because of the high hydrophobicity of the formed resist film. is there.
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 tilted, the inclination angle of the resist film when water droplets start to fall down 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.

The static contact angle, dynamic contact angle, and sliding angle can be measured, for example, as follows.
First, a resist composition solution is spin-coated on a silicon substrate, and then heated for 90 seconds under a predetermined condition, for example, a temperature condition of 110 to 115 ° C., 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.

  In the positive resist composition of the present invention, the measured value of the receding angle in a resist film obtained using the positive resist composition is preferably 55 ° (°) or more, and preferably 55 to 150 °. More preferably, it is 55 to 130 °, particularly preferably 60 to 100 °. When the receding angle is 55 ° or more, the resist film surface is excellent in hydrophobicity and the substance elution suppression effect is improved, and when the receding angle is 150 ° or less, the lithography characteristics and the like are good.

  For the same reason, the positive resist composition of the present invention preferably has a measured value of a static contact angle in a resist film obtained by using the resist composition of 70 ° or more, 70 to 95 °. It is more preferable that it is, and it is especially preferable that it is 80-90 degrees.

  The size of the above-mentioned static contact angle, receding angle, etc. can be adjusted by adjusting the composition of the resist composition, for example, the type of the component (A), the proportion of the structural unit (a1) in the component (A), etc. . For example, the higher the proportion of the structural unit (a1) in the component (A), the higher the hydrophobicity of the resulting resist composition, and the larger the static contact angle and receding angle.

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.
Further, the contamination of the lens of the exposure apparatus can be reduced, so that it is not necessary to take a protective measure against these, and the process and the exposure apparatus can be simplified.
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 properties, 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 resist pattern forming method of this aspect includes a step of forming a resist film on a support using the positive resist composition of the present invention, a step of exposing the resist film, and developing the resist film to form a resist pattern. Forming a step.
The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
In addition, the support may be a substrate in which an inorganic and / or organic film is provided on the above-described substrate. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include an organic antireflection film (organic BARC).
The 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, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide (TMAH), and preferably rinsed with pure water. The water rinsing can be performed, for example, by dropping or spraying water on the substrate surface while rotating the substrate to wash away the developer on the substrate and the resist composition for immersion exposure dissolved by the developer. And a resist pattern can be formed by drying.
An organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.
The wavelength used for the exposure is not particularly limited, and 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 include a fluorine-based compound such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. 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.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.

[Synthesis Example 1]
(Synthesis of 7,7,7-trifluoro-3-ethyl-3-heptanol)
In a four-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel, and a thermometer, 1.3 g of magnesium, 10.0 g of 1-bromo-4,4,4-trifluorobutane, and 20 g of tetrahydrofuran are put in a conventional manner. A Grignard reagent was prepared. To the obtained Grignard reagent, a mixed solution of 5.0 g of 3-pentanone and 4 g of tetrahydrofuran was added dropwise at 25 to 35 ° C. over 30 minutes, and further stirred at the same temperature for 1 hour. The reaction mixture was treated by a conventional method, and the obtained organic layer was washed with water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure, and 7,7,7-trifluoro-3-ethyl-3-heptanol was pale yellow. 7.9 g was obtained as an oil.

(Synthesis of 7,7,7-trifluoro-3-ethyl-3-heptyl methacrylate)
In a four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 7.9 g of 7,7,7-trifluoro-3-ethyl-3-heptanol obtained above and 0.2 g of 4-dimethylaminopyridine were obtained. Then, 7.1 g of triethylamine and 10 g of acetritonyl were added and dissolved by stirring. To the solution, 6.7 g of methacrylic acid chloride was added dropwise at about 75 ° C. over 30 minutes, and further stirred at the same temperature for 2 hours. The reaction solution was cooled to room temperature, washed once with a mixed solution of 8.8 g of potassium carbonate and 100 ml of water, once with 10% brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The concentrate was purified by silica gel column chromatography to obtain 5.7 g of 7,7,7-trifluoro-3-ethyl-3-heptyl methacrylate.
¹ H-NMR data of the obtained 7,7,7-trifluoro-3-ethyl-3-heptyl methacrylate are as follows.
¹ H-NMR (CDCl ₃ ) δ: 0.82 to 0.87 (tr, 6H, —CH ₃ ), 1.46 to 1.58 (m, 2H, —CH ₂ —), 1.78 to 1 .97 (m, 9H, ═C—CH ₃ , —C—CH ₂ —), 1.98 to 2.16 (m, 2H, CF ₃ CH ₂ —), 5.49 (s, 1H, C = _{CH 2), 6.01 (s,} 1H, C = CH 2)
From the above results, it was confirmed that the structure was represented by the following formula (I-1).

(Synthesis of resin)
In a four-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, 30 g of tetrahydrofuran, 5.63 g of the 7,7,7-trifluoro-3-ethyl-3-heptyl methacrylate obtained above, γ -Butyrolactone methacrylate 3.40g and 3-hydroxy-1-adamantyl methacrylate 2.36g were put, and after nitrogen substitution, it heated up at 67 degreeC. While maintaining the temperature, a solution obtained by dissolving 0.37 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 3 g of tetrahydrofuran was added dropwise over 10 minutes. After completion of the dropwise addition, the mixture was stirred for 6 hours while maintaining the temperature, and then cooled to room temperature. The obtained polymerization reaction solution was dropped into a large amount of a methanol / water mixed solution, and the precipitated resin was filtered, washed and dried to obtain 7.4 g of a white solid resin as a target product. The weight average molecular weight of the obtained resin was 11200, and the molecular weight distribution was 1.8 (GPC analysis, polystyrene conversion). Moreover, about the composition ratio of the obtained resin, as a result of ¹³ C-NMR analysis, 7,7,7-trifluoro-3-ethyl-3-heptyl methacrylate, γ-butyrolactone methacrylate and 3-hydroxy-1-adamantyl methacrylate The copolymerization molar ratio was 32:44:24, and it was confirmed that the resin was represented by the following chemical formula (2).

[Synthesis Example 2]
(Synthesis of 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl methacrylate)
In a four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 7.3 g of 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 4-dimethylaminopyridine, 0. 2 g, triethylamine 4.9 g, and acetone 20 g were added and dissolved by stirring. To the solution, 4.6 g of methacrylic acid chloride was added dropwise at about 5 ° C. over 30 minutes, and the mixture was further stirred at the same temperature for 3 hours. The reaction solution was washed with water to obtain 7.5 g of 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl methacrylate. ¹ H-NMR data of the obtained 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl methacrylate are as follows.
¹ H-NMR (CDCl ₃ ) δ: 1.95 (s, 3H, ═C—CH ₃ ), 2.01 (s, 3H, C—CH ₃ ), 5.71 (s, 1H, C═CH) _{2), 6.18 (s, 1H} , C = CH 2)
From the above results, the following structure was confirmed.

(Synthesis of resin)
To a 4-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, 30 g of tetrahydrofuran, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl obtained above After 5.00 g of methacrylate, 3.40 g of γ-butyrolactone methacrylate and 2.36 g of 3-hydroxy-1-adamantyl methacrylate were added and purged with nitrogen, the temperature was raised to 67 ° C. While maintaining the temperature, a solution obtained by dissolving 0.37 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 3 g of tetrahydrofuran was added dropwise over 10 minutes. After completion of the dropwise addition, the mixture was stirred for 6 hours while maintaining the temperature, and then cooled to room temperature. The obtained polymerization reaction liquid was dropped into a large amount of a methanol / water mixed solution, and the precipitated resin was filtered, washed and dried to obtain 7.0 g of a white solid resin as a target product. The weight average molecular weight of the obtained resin was 10600, and the molecular weight distribution was 1.6 (GPC analysis, polystyrene conversion). Moreover, about the composition ratio of the obtained resin, as a result of ¹³ C-NMR analysis, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propyl methacrylate, γ-butyrolactone methacrylate and 3- The copolymerization molar ratio of hydroxy-1-adamantyl methacrylate was 39:39:22, and it was confirmed that the resin was represented by the following chemical formula (4).

[Synthesis Example 3]
(Synthesis of 1,1,1-trifluoro-2-methyl-2-heptanol)
In a four-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, 24.9 g of trimethyl (trifluoromethyl) silane, 16.0 g of 2-heptanone, 38 g of tetrahydrofuran, tetrabutylammonium fluoride trihydrate 350 mg was added and reacted according to a conventional method. To the obtained reaction solution, 17.5 g of hydrochloric acid was added dropwise at 25 to 48 ° C. over 30 minutes, and the mixture was further stirred at about 48 ° C. for 2 hours. The reaction mixture was treated by a conventional method, and the obtained organic layer was washed with brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure, and 1,1,1-trifluoro-2-methyl-2-heptanol was diluted lightly. 26.4 g was obtained as a brown oil.

(Synthesis of 1,1,1-trifluoro-2-methyl-2-heptyl methacrylate)
In a four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, 21.4 g of 1,1,1-trifluoro-2-methyl-2-heptanol obtained above and 0.6 g of 4-dimethylaminopyridine were obtained. Then, 23.3 g of triethylamine and 35 g of acetritonyl were added and dissolved by stirring. To the solution, 20.9 g of methacrylic acid chloride was added dropwise at about 75 ° C. over 30 minutes, and the mixture was further stirred at the same temperature for 7 hours. The reaction solution was cooled to room temperature, washed once with a mixture of 27.6 g of potassium carbonate and 300 ml of water, once with 10% brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The concentrate was purified by silica gel column chromatography to obtain 14.0 g of 1,1,1-trifluoro-2-methyl-2-heptyl methacrylate. The ¹ H-NMR data of the obtained 1,1,1-trifluoro-2-methyl-2-heptyl methacrylate is as follows.
¹ H-NMR (CDCl ₃ ) δ: 0.85 to 0.90 (tr, 3H, —CH ₃ ), 1.20 to 1.49 (m, 6H, —CH ₂ —CH ₂ —CH ₂ —) 1.70 (s, 3H, C—CH ₃ ), 1.93 (s, 3H, ═C—CH ₃ ), 1.96 to 2.26 (m, 2H, C—CH ₂ —), 5 .59 (s, 1H, C = CH ₂ ), 6.10 (s, 1H, C = CH ₂ )
From the above results, the following structure was confirmed.

(Synthesis of resin)
In a four-necked flask equipped with a nitrogen blowing tube, a reflux condenser, a dropping funnel and a thermometer, 30 g of tetrahydrofuran, 5.05 g of 1,1,1-trifluoro-2-methyl-2-heptyl methacrylate obtained above, γ -Butyrolactone methacrylate 3.40g and 3-hydroxy-1-adamantyl methacrylate 2.36g were put, and after nitrogen substitution, it heated up at 67 degreeC. While maintaining the temperature, a solution obtained by dissolving 0.37 g of 2,2′-azobis (2,4-dimethylvaleronitrile) in 3 g of tetrahydrofuran was added dropwise over 10 minutes. After completion of the dropwise addition, the mixture was stirred for 6 hours while maintaining the temperature, and then cooled to room temperature. The obtained polymerization reaction solution was dropped into a large amount of a methanol / water mixed solution, and the precipitated resin was separated by filtration, washed and dried to obtain 8.1 g of the desired product as a white solid. The weight average molecular weight of the obtained resin was 12800, and the molecular weight distribution was 2.0 (GPC analysis, polystyrene conversion). Moreover, about the composition ratio of the obtained resin, as a result of ¹³ C-NMR analysis, 1,1,1-trifluoro-2-methyl-2-heptyl methacrylate, γ-butyrolactone methacrylate and 3-hydroxy-1-adamantyl methacrylate The copolymer molar ratio was 37:41:22, and the resin was confirmed to be represented by the following chemical formula (5).

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

Here, the unit of the compounding amount shown in [] in Table 1 is part by mass. The abbreviations in Table 1 have the following meanings.
(A) -2: resin represented by the chemical formula (2).
-(A) -3: Resin represented by the following chemical formula (3).
(A) -4: Resin represented by the chemical formula (4).
(A) -5: Resin represented by the chemical formula (5).
-(B) -1: Triphenylsulfonium nonafluorobutanesulfonate.
(B) -2: (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate.
-(D) -1: Triethanolamine.
-(S) -1: Mixed solvent of PGMEA / PGME = 6/4 (mass ratio).

  The (A) -3 was copolymerized by a known dropping polymerization method using a monomer for deriving each structural unit. The weight average molecular weight (Mw) was 10,000, and the dispersity (Mw / Mn) was 1.8.

The following evaluation was performed using the obtained resist composition.
<Hydrophobic evaluation>
For the resist compositions of Example 1 and Comparative Example 1, the static contact angle and the dynamic contact angle (retraction angle) of the resist film surface before and after exposure (hereinafter referred to as contact angle, etc.) in the following procedure. Was measured to evaluate the hydrophobicity of the resist film.
Each of the resist compositions of Example 1 and Comparative Example 1 was coated on an 8-inch silicon wafer using a spinner, pre-baked (PAB) at 110 ° C. for 60 seconds on a hot plate, and dried. A resist film having a thickness of 150 nm was formed.
50 μL of water was dropped onto the surface of the resist film (resist film before exposure), and the contact angle and the like were measured using DROP MASTER-700 manufactured by Kyowa Interface Science Co., Ltd.

In addition, a resist film is formed in the same manner as described above, and ArF excimer laser is used using an ArF exposure apparatus NSR-S-302A (Nikon Corporation; NA (numerical aperture) = 0.60, 2/3 annular illumination). Open frame exposure (exposure not through a mask) was performed at (193 nm) (exposure amount 20 mJ / cm ² ), and PEB treatment at 90 ° C. for 60 seconds or PEB treatment at 150 ° C. for 60 seconds was performed. After PEB treatment, the contact angle on the surface of the resist film (resist film after exposure) was measured in the same manner as described above.

Table 2 shows the measurement results such as the contact angle of the resist film before and after exposure. Table 2 also shows PEB / PAB temperature conditions for each resist composition.
As shown in these results, when compared under the same baking conditions, Example 1 had a larger static contact angle and dynamic contact angle (retraction angle) before and after exposure than Comparative Example 1. . From this result, it was confirmed that the resist film obtained using the resist composition of Example 1 was a film having higher hydrophobicity than the resist film obtained using the resist composition of Comparative Example 1.

<Lithography characteristics evaluation>
"Resolution and sensitivity"
About the resist composition of Example 1 and Comparative Examples 1-3, the resist pattern was formed in the following procedures, respectively.
An organic antireflection film composition “ARC-29” (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.
Next, the resist composition solutions of Example 1 and Comparative Examples 1 to 3 were uniformly applied using a spinner, respectively, and baked (PAB) at 90 ° C. for 60 seconds to form a resist film (film thickness 150 nm). Formed.
An ArF excimer laser (193 nm) is selected for the resist film through a mask pattern using an ArF exposure apparatus NSR-S302A (Nikon Corp .; NA (numerical aperture) = 0.60, 2/3 annular illumination). Irradiated. Then, PEB treatment is performed at 90 ° C. for 60 seconds, and further development processing is performed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution at 23 ° C. for 30 seconds, and then pure water is used for 30 seconds. An attempt was made to form a line-and-space (1: 1) resist pattern (hereinafter referred to as L / S pattern) by rinsing with water and drying by shaking.
As a result, in the example using the resist composition of Example 1 and Comparative Example 1, an L / S pattern having a line width of 120 nm (pitch 240 nm) was formed.
At this time, the optimum exposure amount (Eop) (unit: mJ / cm ² (energy amount per unit area)), that is, the sensitivity at which an L / S pattern having a line width of 120 nm and a pitch of 240 nm is formed was determined. The results are shown in Table 3.
On the other hand, in the example using the resist compositions of Comparative Examples 2 to 3, the resist pattern was not resolved.

"LWR (Line Wise Roughness)"
In each L / S pattern formed by the Eop, the line width was measured at five locations in the longitudinal direction of the line with a length measuring SEM (scanning electron microscope, trade name: S-9220, manufactured by Hitachi, Ltd.). From the results, a standard deviation (s) triple value (3 s) was calculated as a measure of LWR. The results are shown in Table 3. It was confirmed that the resist composition of Example 1 was superior in the value of 3 s to the resist composition of Comparative Example 1. Note that the smaller the value of 3s, the smaller the roughness of the line width, which means that a more uniform L / S pattern was obtained.

  As shown in the above results, it was confirmed that the resist composition of Example 1 can form a resist film having higher hydrophobicity than the conventional resist composition, and has good lithography properties with reduced LWR. It was done.

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

Claims (5)

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 a copolymer having a structural unit (a1) represented by the following general formula (II).

[In formula (II), R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{1 to} R ³ each independently represents an alkyl group or a fluorinated alkyl group. However, the fluorinated alkyl group is a group in which no fluorine atom is bonded to the carbon atom adjacent to the tertiary carbon atom to which R ^{1 to} R ³ are bonded, and at least one of R ^{1 to} R ³ . One is the fluorinated alkyl group. R ² and R ³ may form one ring structure. ]   The positive resist composition according to claim 1, wherein the copolymer further comprises a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.   The positive resist composition according to claim 1, wherein the copolymer further has a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.   Furthermore, the positive resist composition as described in any one of Claims 1-3 containing a nitrogen-containing organic compound (D).   A step of forming a resist film on a support using the positive resist composition according to any one of claims 1 to 4, a step of exposing the resist film, and developing the resist film to form a resist pattern A resist pattern forming method including a step of forming a film.

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