JP4657883B2 - Resist pattern forming method - Google Patents

Description

  The present invention relates to a positive resist composition for thermal flow, a resist pattern forming method, a polymer compound, and a positive resist composition using the polymer compound.

In lithography technology, for example, a resist film made of a resist material is formed on a substrate, and the resist film is selectively exposed to light such as light or an electron beam through a mask on which a predetermined pattern is formed. And a development process is performed to form a resist pattern having a predetermined shape on the resist film. A resist material in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist material that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has rapidly progressed due to advances in lithography technology.
As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but at present, mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. In addition, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.

Resist materials are required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions. As a resist material satisfying such requirements, a chemically amplified resist containing a base resin whose alkali solubility is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. For example, a positive chemically amplified resist contains, as a base resin, a resin whose alkali solubility is increased by the action of an acid and an acid generator. When a resist pattern is formed, an acid is generated from the acid generator by exposure. The exposed part becomes alkali-soluble.
Up to now, as the base resin for chemically amplified resist, polyhydroxystyrene (PHS), which is highly transparent to KrF excimer laser (248 nm), and a resin whose hydroxyl group is protected with an acid dissociable, dissolution inhibiting group (PHS resin) Has been used. However, since the PHS resin has an aromatic ring such as a benzene ring, the transparency to light having a wavelength shorter than 248 nm, for example, 193 nm, is not sufficient. Therefore, a chemically amplified resist having a PHS-based resin as a base resin component has drawbacks such as low resolution in a process using 193 nm light, for example.
Therefore, as a resist base resin currently used in ArF excimer laser lithography and the like, since it has excellent transparency near 193 nm, a resin (acrylic resin) having a structural unit derived from (meth) acrylic ester is used. System resin) is mainly used (see, for example, Patent Document 1).

On the other hand, in addition to countermeasures for ultra-miniaturization from the resist material side, research and development of techniques that exceed the resolution limit of resist materials are being conducted from the aspect of pattern formation methods.
As one of such miniaturization techniques, recently, a thermal flow process has been proposed in which after a resist pattern is formed by a normal lithography technique, the resist pattern is subjected to heat treatment to reduce the pattern size (for example, (See Patent Documents 2 and 3).
In the thermal flow process, after a resist pattern is once formed by photolithography technology, the resist pattern is heated, softened, and flowed in the gap direction of the pattern, so that the resist pattern pattern size, that is, the resist pattern is formed. This is a method of reducing the size of a portion (hole diameter of a hole pattern, space width of a line and space (L & S) pattern, etc.).
JP 2003-241385 A JP 2000-188250 A JP 2000-356850 A

However, in the resist composition used for the conventional ArF excimer laser lithography and the like, the glass transition temperature of the base resin is high, so the softening of the base resin at the heating temperature in the thermal flow process is insufficient, and due to thermal flow There is a problem that it is difficult to form a resist pattern.
The present invention has been made in view of the above circumstances, and in a thermal flow process using a resist composition used for ArF excimer laser lithography or the like, a positive type for thermal flow having excellent controllability of resist pattern size. It is an object of the present invention to provide a resist composition, a resist pattern forming method, a polymer compound suitable for this, and a positive resist composition suitable for thermal flow.

The present inventors propose the following means in order to solve the above problems.
That is, the present invention provides a substrate using a positive resist composition for thermal flow comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure. A resist pattern forming method comprising a step of forming a resist film thereon, a step of exposing the resist film, a step of developing the resist film to form a resist pattern, and a step of performing a thermal flow process , wherein the resin component (A) is a structural unit (a1) in which a hydrogen atom of an alkali-soluble group (i) having a hydrogen atom is substituted by an acid dissociable, dissolution inhibiting group (I) represented by the following general formula (1): It is a resist pattern formation method characterized by containing the polymer compound (A1) to contain.

［式中、Ｚは脂肪族環式基を表し；ｎは０〜３の整数である。］

Wherein Z represents an aliphatic cyclic group; n is an integer of 0 to 3. ]

In the present specification and claims, “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer).
“Exposure” is a concept that includes general irradiation of radiation.

  According to the present invention, in a thermal flow process using a resist composition used for ArF excimer laser lithography and the like, a positive resist composition for thermal flow having excellent controllability of resist pattern size, a resist pattern forming method, and the like are suitable. And a positive resist composition suitable for thermal flow and high molecular compounds.

≪Positive resist composition for thermal flow≫
The present invention 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) which generates an acid upon exposure (hereinafter referred to as component (B). In particular, the positive resist composition is suitable for thermal flow.
In the positive resist composition of the present invention, the component (A) is alkali-insoluble before exposure, and when an acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group dissociates. As a result, the alkali solubility of the entire component (A) is increased and the alkali-insoluble is changed to alkali-soluble. Therefore, when a resist film obtained by using a positive resist composition is selectively exposed in the formation of a resist pattern, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, alkali development can be performed.

<(A) component>
In the present invention, the component (A) has a configuration in which the hydrogen atom of the alkali-soluble group (i) having a hydrogen atom is substituted with the acid dissociable, dissolution inhibiting group (I) represented by the general formula (1). The high molecular compound (A1) containing a unit (a1) is contained.
Preferably, the polymer compound (A1) further includes a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Preferably, the polymer compound (A1) further includes a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.

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.
The “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
In the acrylate ester, as the lower alkyl group as a substituent at the α-position, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, Examples include lower linear or branched alkyl groups such as isopentyl group and neopentyl group.
In the present invention, the α-position of the acrylate ester is preferably a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorine atom. A lower alkyl group is more preferable, and a hydrogen atom or a methyl group is most preferable in terms of industrial availability.

・ Structural unit (a1)
The structural unit (a1) is a structural unit in which the hydrogen atom of the alkali-soluble group (i) having a hydrogen atom is substituted with the acid dissociable, dissolution inhibiting group (I) represented by the general formula (1). . That is, the structural unit (a1) is a structural unit (a0) containing an alkali-soluble group (i) having a hydrogen atom, and the hydrogen atom of the alkali-soluble group (i) in the structural unit (a0) is It is constituted by substitution with the acid dissociable, dissolution inhibiting group (I) represented by (1).
Examples of the alkali-soluble group (i) having a hydrogen atom include a carboxy group and a hydroxy group. Of these, a carboxy group is preferred.
Examples of the structural unit containing an alkali-soluble group (i) having a hydrogen atom include structural units formed by cleavage of ethylenic double bonds such as acrylic acid and hydroxystyrene. Among them, a structural unit constituted by cleavage of an ethylenic double bond of acrylic acid effective for an ArF excimer laser is preferable.

In the general formula (1), Z represents an aliphatic cyclic group.
Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity. Preferably, it is a monocyclic group because the effects of the present invention are improved.
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. The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
Specific examples of such aliphatic cyclic groups include monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes that may or may not be substituted with a lower alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from polycycloalkane. 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. Of these, groups in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane or cyclohexane are preferred.

In the general formula (1), n is an integer of 0 to 3, preferably 0 or 1, and most preferably 0.
Specific examples of preferred structural units as the structural unit (a1) are shown below.

Among the above, structural units represented by chemical formulas (a1-2-9), (a1-2-10), (a1-2-22) to (a1-2-25) are preferable, and chemical formula (a1-2) It is more preferable to use at least one selected from -9), (a1-2-10), (a1-2-22), and (a1-2-23).
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 from 5 to 60 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, and 25 to 55 mol% is most preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a1) can be sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
The polymer compound (A1) preferably contains a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Here, the lactone-containing cyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
The lactone cyclic group 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.

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

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

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

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

R in the general formulas (a2-1) to (a2-5) is the same as the hydrogen atom, halogen atom, lower alkyl group or halogenated lower alkyl group which may be bonded to the α-position of the acrylate ester.
The lower alkyl group for R ′ is the same as the lower alkyl group for R which may be bonded to the α-position of the acrylate ester.
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.

  Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-5), and at least one selected from general formulas (a2-1) to (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 60 mol%, more preferably from 10 to 50 mol%, based on the total of all the structural units constituting the polymer compound (A1). Preferably, 20-50 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) is sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

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

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

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

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

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

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

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

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
In the polymer compound (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, and 5 to 40 mol% with respect to all the structural units constituting the polymer compound (A1). More preferably, 5-25 mol% is further more preferable.

・ Structural unit (a4)
The polymer compound (A1) may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit not classified into the structural units (a1) to (a3) described above, and is for ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser) A number of conventionally known resins can be used for resist resins such as
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may be substituted with a linear or branched alkyl group having 1 to 5 carbon atoms.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

  When such a structural unit (a4) is contained in the polymer compound (A1), the structural unit (a4) is contained in an amount of 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 contained.

The polymer compound (A1) is a polymer having at least the structural unit (a1), and is preferably a copolymer further having the structural units (a2) and / or (a3). Examples of such a copolymer include a copolymer composed of the structural units (a1) and (a2), a copolymer composed of the structural units (a1), (a2), and (a3).
In the present invention, the polymer compound (A1) particularly preferably includes a combination of structural units such as the following formulas (A1-11) to (A1-12).

［式中、Ｒは前記と同じであり、ｈは１又は２である。］

[Wherein, R is the same as defined above, and h is 1 or 2. ]

［式中、Ｒは前記と同じである。］

[Wherein, R is the same as defined above. ]

The polymer compound (A1) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). it can.
Further, in the polymer compound (A1), a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH is used in combination in the above polymerization. it may be introduced -C _{(CF 3)} 2 -OH group at the terminal. As described above, a polymer compound into which a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom is used to reduce development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

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 the dry etching resistance and resist pattern cross-sectional shape that are larger than the lower limit of this range are good.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. In addition, Mn shows a number average molecular weight.

In the component (A), as the polymer compound (A1), one type may be used alone, or two or more types may be used in combination.
In the component (A), the content of the polymer compound (A1) is preferably 70% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass.

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

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

[Wherein, R ⁵¹ represents a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; R ⁵² represents a hydrogen atom, a hydroxyl group, a halogen atom, linear or A branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group; R ⁵³ is an aryl group which may have a substituent; u '' Is an integer of 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 is a hydrogen atom, a hydroxyl group, a halogen atom, a linear or branched alkyl group, a linear or branched alkyl halide group, or a linear or branched alkoxy group.
In R ⁵² , examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and a fluorine atom is preferable.
In R ⁵² , the alkyl group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
In R ⁵² , the halogenated alkyl group is a group in which part or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms. Examples of the alkyl group herein are the same as the “alkyl group” in R ⁵² . Examples of the halogen atom to be substituted include the same as those described above for the “halogen atom”. In the halogenated alkyl group, it is desirable that 50 to 100% of the total number of hydrogen atoms are substituted with halogen atoms, and it is more preferable that all are substituted.
In R ⁵² , the alkoxy group is linear or branched, and the carbon number thereof is preferably 1 to 5, particularly 1 to 4, and more preferably 1 to 3.
Among these, R ⁵² is preferably a hydrogen atom.

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

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

  The acid generator represented by general formula (b-0) can be used alone or in combination of two or more.

  As other onium salt-based acid generators represented by the general formula (b-0), for example, compounds represented by the following general formula (b-1) or (b-2) are also preferably used. It is done.

［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 most preferably a phenyl group or a naphthyl group, respectively.

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

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

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

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

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

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

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

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

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

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

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

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

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

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

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

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

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

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

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

The alkyl group or halogenated alkyl group having no substituent 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 fluorinated, more preferably 70% or more, and even more preferably 90% or more. This is preferable because the strength of the acid is increased. Most preferably, it is a fully fluorinated alkyl group in which a hydrogen atom is 100% fluorine-substituted.

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

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

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

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

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, it is particularly preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B). Specifically, triphenylsulfonium nonafluorobutanesulfonate (TPS-PFBS) and the like.
Content of (B) component in the positive resist composition of this invention is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(D) component>
In the positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as the component (D)) is further added as an optional component in order to improve the resist pattern shape, stability with time, etc. Can be blended.
Since a wide variety of components (D) have been proposed, any known one may be used, but aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred. .
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms. Specific examples thereof include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di-n-heptylamine, Dialkylamines such as di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptyl Trialkylamines such as amine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n -Ok Noruamin, alkyl alcohol amines such as tri -n- octanol amine.
Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are most preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.
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.

<Optional component>
In the positive resist composition of the present invention, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof (E) is used as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape, retention stability, and the like. ) (Hereinafter referred to as component (E)).
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

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

The positive resist composition of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol and derivatives thereof;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate, monomethyl ether, monoethyl ether, monopropyl of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as ethers, monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether;
Cyclic ethers such as dioxane and esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, etc. Can be mentioned.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA 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 5-15% by mass.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention can be performed, for example, as follows.
That is, first, the positive resist composition is applied onto a substrate such as a silicon wafer with a spinner, and prebaking (PAB) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. After this, ArF excimer laser light is selectively exposed through a desired mask pattern using, for example, an ArF exposure apparatus, and then subjected to PEB (post-exposure heating) for 40 to 120 seconds under a temperature condition of 80 to 150 ° C. , Preferably 60-90 seconds. Subsequently, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. In this way, a resist pattern faithful to the mask pattern can be obtained.
An organic or inorganic antireflection film can be provided between the substrate and the coating layer of the resist composition.
The wavelength used for exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray Or the like. The positive resist composition according to the present invention is particularly effective for an ArF excimer laser.

[Thermal flow process (thermal flow process)]
In the resist pattern forming method of the present invention, after the resist pattern is formed as described above, a thermal flow process is further performed.
The thermal flow treatment can be performed as follows, for example.
That is, the resist pattern after the development treatment is softened by heating at least once, preferably 2-3 times, and the resist is allowed to flow, whereby the resist pattern pattern size (for example, the hole pattern hole diameter and the line and space width) ) Is reduced (narrower) than the size immediately after development.
A suitable heating temperature depends on the composition of the resist composition and is not particularly limited as long as it is equal to or higher than the softening point of the resist pattern, but is preferably in the range of 80 to 180 ° C, more preferably 110 to 170 ° C. By setting the heating temperature within this range, there are advantages such as easy control of the pattern size and ease of use in existing apparatuses.
Further, a suitable heating time is not particularly limited as long as it is within a range in which a desired pattern size can be obtained without hindering throughput, but one time can be determined from a normal semiconductor element manufacturing line process. The heating is preferably performed for 10 to 300 seconds, more preferably about 30 to 180 seconds.

The positive resist composition for thermal flow of the present invention has an effect of excellent resist pattern size controllability in a thermal flow process using a resist composition used for ArF excimer laser lithography or the like. The reason is not clear, but is presumed as follows.
Resins used for resist compositions conventionally used in ArF excimer laser lithography and the like have a high glass transition temperature, so that the base resin is insufficiently softened at the heating temperature in the thermal flow process. It is difficult to form a pattern.
The polymer compound (A1) used in the present invention is a resin containing a so-called acetal-type protecting group, and the resin has a glass transition temperature lower than that of a conventional resin. As a result, the resist pattern is sufficiently softened in the thermal flow process, so that it is possible to form a finer resist pattern and improve the controllability of the pattern size.
In the present invention, the glass transition temperature can be lowered than before without lowering the decomposition temperature of the polymer compound (A1). Thereby, it is thought that the lithography characteristics such as the resist pattern shape and resolution before the thermal flow process are maintained without deterioration even after the thermal flow process.
In addition, in the present invention, the effect of improving the substrate adhesion and developer permeability is also obtained.

≪Polymer compound≫
The polymer compound of the present invention (hereinafter referred to as polymer compound (A2)) is an acid dissociable dissolution inhibitor wherein the hydrogen atom of the alkali-soluble group (i) having a hydrogen atom is represented by the general formula (2). The structural unit (a1) ′ substituted with the group (II) is included.
Preferably, the polymer compound (A2) further includes a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
Preferably, the polymer compound (A2) further includes a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.

-Structural unit (a1) '
The structural unit (a1) ′ is a structural unit in which the hydrogen atom of the alkali-soluble group (i) having a hydrogen atom is substituted with the acid dissociable, dissolution inhibiting group (II) represented by the general formula (2). is there. That is, the structural unit (a1) ′ is a structural unit (a0) containing an alkali-soluble group (i) having a hydrogen atom, and the hydrogen atom of the alkali-soluble group (i) in the structural unit (a0) is It is constituted by substitution with an acid dissociable, dissolution inhibiting group (II) represented by the formula (2).
Examples of the alkali-soluble group (i) having a hydrogen atom include a carboxy group and a hydroxy group. Of these, a carboxy group is preferred.
Examples of the structural unit containing an alkali-soluble group (i) having a hydrogen atom include structural units formed by cleavage of ethylenic double bonds such as acrylic acid and hydroxystyrene. Among them, a structural unit constituted by cleavage of an ethylenic double bond of acrylic acid effective for an ArF excimer laser is preferable.

In the general formula (2), Z ′ represents an aliphatic monocyclic group.
The “aliphatic monocyclic group” may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms. The basic ring structure excluding the substituent of the “aliphatic monocyclic 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.
Specific examples of such an aliphatic monocyclic group include, for example, a group in which one or more hydrogen atoms have been removed from a monocycloalkane which may or may not be substituted with a lower alkyl group. It can be illustrated. Specific examples include groups in which one or more hydrogen atoms have been removed from cyclopentane, cyclohexane, or the like.

In the general formula (2), n is an integer of 0 to 3, preferably 0 or 1, and most preferably 0.
Specific examples of preferred structural units as the structural unit (a1) ′ are shown below.

Among the above, structural units represented by chemical formulas (a1-2-22) to (a1-2-25) are preferable, and are selected from chemical formulas (a1-2-22) and (a1-2-23). More preferably, at least one kind is used.
As the structural unit (a1) ′, one type may be used alone, or two or more types may be used in combination.
5-60 mol% is preferable with respect to the sum total of all the structural units which comprise a high molecular compound (A2), and the ratio of structural unit (a1) 'in a high molecular compound (A2) is 10-60 mol%. More preferably, 20 to 60 mol% is more preferable, and 25 to 55 mol% is most preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a1) ′ can be sufficiently obtained, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

Structural unit (a2), structural unit (a3)
In the polymer compound (A2), the structural unit (a2) and the structural unit (a3) are the same as those in the positive resist composition for thermal flow, and a description thereof is omitted.
The structural unit (a4), which is another structural unit, is the same as the positive resist composition for thermal flow, and a description thereof will be omitted.

  The polymer compound (A2) is a polymer having at least the structural unit (a1) ′, and is preferably a copolymer having the structural unit (a2) and / or (a3). Examples of such a copolymer include copolymers composed of the structural units (a1) ′, (a2) and (a3).

In the present invention, the polymer compound (A2) particularly preferably includes a combination of structural units such as the formula (A1-11).
The production method, mass average molecular weight (Mw), and dispersity (Mw / Mn) of the polymer compound (A2) are the same as those of the polymer compound (A1), and the description thereof is omitted.

  The polymer compound (A2) of the present invention is preferably used as a resin component of a resist composition, more preferably used as a resin component of a positive resist composition used for ArF excimer laser lithography and the like. Most preferably, it is used for the resin component of the positive resist composition for thermal flow as described above.

≪Positive resist composition≫
The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) that generates an acid upon exposure. The component contains the polymer compound (A2) of the present invention.
The positive resist composition of the present invention is a positive resist composition particularly suitable for thermal flow.
In the component (A), as the polymer compound (A2), one type may be used alone, or two or more types may be used in combination.
In the component (A), the content of the polymer compound (A2) is preferably 70% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass.
The component (B), other components (component (D), optional component) and the resist pattern forming method are the same as described above, and the description thereof is omitted.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples. However, Example 1 and Example 2 are reference examples.

  Copolymers (A) -1 to (A) -3 were synthesized by the methods shown below using compounds 1 to 5 of monomers represented by the following chemical formula. The production method of Compound 1 is also shown.

[Synthesis example]
-Synthesis | combination of compound 1 THF (tetrahydrofuran) 100mL was put into the eggplant flask, and 9g of methacrylic acid and 13g of triethylamines were added. Next, 15 g of chloromethoxycyclohexane was added dropwise over 30 minutes while cooling with ice. Thereafter, the mixture was stirred at room temperature for 3 h, extracted with ethyl acetate, and concentrated to obtain the compound 1.

-Synthesis | combination of copolymer (A) -1 1000mL of THF was put into the eggplant flask, 15g of the compound 1 obtained by the said synthesis | combination, 13g of the said compound 2, and 9g of the said compounds 3 were added, respectively. Thereafter, 0.8 g of polymerization initiator AIBN (azobisisobutyronitrile) was added and refluxed for 6 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and the concentrated solution was added to 1 L of heptane to cause reprecipitation. Then, the target copolymer (A) -1 was obtained through filtration and drying under reduced pressure.
The obtained copolymer is shown in the following chemical formula (A) -1.
The mass average molecular weight (Mw) was 17500, the dispersity (Mw / Mn) was 1.6, and the composition ratio (molar ratio) by carbon NMR was a1 / b1 / c1 = 31/48/21.

-Synthesis | combination of copolymer (A) -2 1000 mL of THF was put into the eggplant flask, and 25 g of the said compound 5 and 17 g of the said compounds 2 were added, respectively. Thereafter, 0.8 g of polymerization initiator AIBN was added and refluxed for 6 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and the concentrated solution was added to 1 L of heptane to cause reprecipitation. Then, the target copolymer (A) -2 was obtained through filtration and drying under reduced pressure.
The obtained copolymer is shown in the following chemical formula (A) -2.
The mass average molecular weight (Mw) was 14600, the dispersity (Mw / Mn) was 1.8, and the composition ratio (molar ratio) was a2 / b2 = 55/45 by carbon NMR.

-Synthesis | combination of copolymer (A) -3 1000mL of THF was put into the eggplant flask, and 28g of the said compound 4 and 14g of the said compounds 2 were added, respectively. Thereafter, 0.8 g of polymerization initiator AIBN was added and refluxed for 6 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and the concentrated solution was added to 1 L of heptane to cause reprecipitation. Then, the target copolymer (A) -3 was obtained through filtration and drying under reduced pressure.
The obtained copolymer is shown in the following chemical formula (A) -3.
The mass average molecular weight (Mw) was 10,000, the dispersity (Mw / Mn) was 1.7, and the composition ratio (molar ratio) was a3 / b3 = 42/58 by carbon NMR.

(Examples 1-2, Comparative Example 1)
[Evaluation of Glass Transition Temperature (Tg) and Decomposition Temperature (Td)]
For the copolymers (A) -1 to (A) -3 obtained above, Td was 10 ° C./min. With a thermal analyzer DSC6200 (manufactured by Seiko Instrument). The measurement was performed under the temperature rising conditions. Tg was 10 ° C./min. With a thermal analyzer TG / DTA6200 (manufactured by Seiko Instrument). The measurement was performed under the temperature rising conditions. The results are shown in Table 1.

From Table 1, it was confirmed that the copolymers of Examples 1 and 2 had a glass transition temperature lower than that of the copolymer of Comparative Example 1 and the decomposition temperature was comparable.
The copolymer (A) -1 containing a structural unit substituted with an acid dissociable, dissolution inhibiting group having an aliphatic monocyclic group in Example 1 has the aliphatic polycyclic group in Example 2. It was confirmed that the glass transition temperature was lower than that of the copolymer (A) -2 containing a structural unit substituted with an acid dissociable, dissolution inhibiting group.

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

Each abbreviation in Table 2 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(A) -1 to (A) -3: The copolymers (A) -1 to (A) -3 are shown respectively.
(B) -1: Triphenylsulfonium nonafluorobutanesulfonate (D) -1: Triethanolamine (S) -1: PGMEA / EL = 6/4 (mass ratio)

The following evaluation was performed using the obtained positive resist composition solution.
An organic antireflection film material (product name: ARC29A, manufactured by Brewer Science) is applied onto an 8-inch silicon wafer and baked at 205 ° C. for 60 seconds to form a 77 nm-thick antireflection film. It was.
The positive resist composition obtained above is uniformly coated on the substrate using a spinner, pre-baked on a hot plate at 100 ° C. for 60 seconds, and dried to form a resist layer having a thickness of 200 nm. Formed.

Next, an ArF excimer laser (193 nm) was passed through the mask pattern using an ArF exposure apparatus (wavelength 193 nm) NSR-S302 (product name, manufactured by Nikon, NA (numerical aperture) = 0.6, σ = 0.75). Selectively exposed.
Then, PEB treatment was performed under conditions of 110 ° C. for 60 seconds, and further developed with a developer (2.38 mass% tetramethylammonium hydroxide aqueous solution) at 23 ° C. for 30 seconds, and then purified water was used for 15 seconds. Rinse and shake-dry.
Thereafter, the resist pattern was formed by heating at 100 ° C. for 60 seconds and drying.
As a result, a plurality of hole patterns (pitch 750 nm) having a diameter of 150 nm were obtained.

[Evaluation of controllability of resist pattern size by thermal flow treatment]
The resist pattern obtained above was subjected to thermal flow treatment under the following five temperature conditions, and changes in the diameter (nm) of the hole pattern were evaluated.
1) 140 ° C., 90 seconds; 2) 145 ° C., 90 seconds; 3) 150 ° C., 90 seconds; 4) 155 ° C., 90 seconds; 5) 160 ° C., 90 seconds

In the above evaluation, the flow rate of the hole pattern with a diameter of 155 nm is shown in a graph in FIG.
The horizontal axis shows the temperature (° C.) of the thermal flow treatment, and the vertical axis shows the hole diameter (diameter, nm) after the thermal flow treatment.

From the graph shown in FIG. 1, it was confirmed that in Examples 3 to 4 according to the present invention, the size of the hole diameter was changed by the thermal flow treatment, and the resist pattern size was controlled. In addition, it was confirmed that Example 3 formed a finer resist pattern than Example 4.
On the other hand, in Comparative Example 2, no dimensional change in the hole diameter was observed.

It is the graph which showed the result of the Example.

Claims (5)

A resist film is formed on a substrate by using a positive resist composition for thermal flow including 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. A resist pattern forming method including a step of exposing, a step of exposing the resist film, a step of developing the resist film to form a resist pattern, and a step of performing a thermal flow process ,
In the resin component (A), the hydrogen atom of the alkali-soluble group (i) having a hydrogen atom is represented by the following general formula (1).

[Wherein Z represents an aliphatic cyclic group; n is an integer of 0 to 3. ]
A resist pattern forming method characterized by containing a polymer compound (A1) containing a structural unit substituted (a1) by in represented by acid dissociable, dissolution inhibiting group (I). The resist pattern forming method according to claim 1, wherein the polymer compound (A1) further includes a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group. The resist pattern forming method according to claim 1, wherein the polymer compound (A1) further comprises a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. The method for forming a resist pattern according to claim 1, wherein the aliphatic cyclic group is a monocyclic group. The said positive resist composition for thermal flows is a resist pattern formation method as described in any one of Claims 1-4 which contains a nitrogen-containing organic compound (D) further.

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