JP2007334278A - Positive resist composition for immersion exposure and method of forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition for immersion exposure, which is suitable for immersion exposure and forms a resist film having high hydrophobicity of a surface thereof and good lithography characteristics, and also to provide a method of forming a resist pattern. <P>SOLUTION: The positive resist composition for immersion exposure comprises: a resin ingredient (A) which is increased in alkali solubility by the action of an acid; and an acid generator ingredient (B) which generates an acid upon exposure to light, wherein the resin ingredient (A) comprises: a resin (A1) of the main-chain-cyclic type containing fluorine atoms and having no acid-dissociable group; and a resin (A2) having a constitutional unit (a) derived from acrylic acid and containing no fluorine atom. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positive resist composition for immersion exposure used for immersion exposure (immersion lithography) and a resist pattern forming method.

  Lithography is frequently used to manufacture fine structures in various electronic devices such as semiconductor devices and liquid crystal devices. However, with the miniaturization of device structures, it is required to make resist patterns finer in the lithography process. At present, it is possible to form a fine resist pattern with a line width of about 90 nm in a state-of-the-art region using, for example, an ArF excimer laser by lithography. Required.

In order to achieve such fine pattern formation, the development of an exposure apparatus and a corresponding resist is the first.
As the resist, a chemically amplified resist containing an acid generator that generates an acid upon irradiation with radiation and a base resin whose alkali solubility is changed by the action of the acid generated from the acid generator has attracted attention. Development is underway. According to the chemically amplified resist, not only high resolution is achieved, but also the catalytic reaction and chain reaction of the acid generated by radiation irradiation can be used, the quantum yield is 1 or more, and high sensitivity can be achieved. .
In a positive chemically amplified resist, a resin having an acid dissociable, dissolution inhibiting group is mainly used. Examples of the acid dissociable, dissolution inhibiting group include an acetal group such as an ethoxyethyl group, a tertiary alkyl group such as a tert-butyl group, a tert-butoxycarbonyl group, and a tert-butoxycarbonylmethyl group. Moreover, as a structural unit having an acid dissociable, dissolution inhibiting group in a resin component of a conventional ArF resist composition, as shown in Patent Document 1 below, a tertiary ester compound of (meth) acrylic acid, for example, 2-alkyl A structural unit derived from 2-adamantyl (meth) acrylate or the like is generally used. “(Meth) acrylic acid” means one or both of an acrylate ester having a hydrogen atom bonded to the α-position and a methacrylate ester having a methyl group bonded to the α-position.

On the other hand, in the exposure apparatus, it is common to shorten the wavelength of the light source used, increase the numerical aperture (NA) of the lens (to increase the NA), or the like. For example, in general, the g-line with a main spectrum of a mercury lamp of 436 nm is used at a resist resolution of about 0.5 μm, and the i-line with a main spectrum of a mercury lamp of 365 nm is used at about 0.5 to 0.30 μm. In the case of about 0.30 to 0.15 μm, 248 nm KrF excimer laser light is used, and in the case of about 0.15 μm or less, 193 nm ArF excimer laser light is used. For further miniaturization, the use of F ₂ excimer laser (157 nm), Ar ₂ excimer laser (126 nm), EUV (extreme ultraviolet; 13.5 nm), EB (electron beam), X-ray, etc. has been studied. Yes.
However, shortening the wavelength of the light source requires an expensive new exposure apparatus. Further, when the NA is increased, the resolution and the depth of focus are in a trade-off relationship. Therefore, there is a problem that the depth of focus decreases even if the resolution is increased.

Under such circumstances, a method called immersion exposure (immersion lithography) has been reported (for example, see Non-Patent Documents 1 to 3). This method uses a solvent (liquid) having a refractive index larger than the refractive index of air at the time of exposure between a lens and a resist film on the wafer, which is conventionally filled with an inert gas such as air or nitrogen. It is a method including a step of performing exposure (immersion exposure) in a state filled with an immersion medium.
According to such immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when a light source having a shorter wavelength or a high NA lens is used can be achieved, and the focus can be reduced. It is said that there is no decrease in depth. 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. Currently, water is mainly studied as an immersion medium.
JP-A-10-161313 Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, pp. 3306-3309. Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, pp. 2353-2356. Proceedings of SPIE (USA) 2002, 4691, pp. 459-465.

However, there are still many unknown points in immersion exposure, and it is actually difficult to form a fine pattern at a level where it can actually be used. For example, in immersion exposure, as described above, the immersion medium comes into contact with the resist film and the lens during immersion exposure. For this reason, the resist film changes in quality due to elution of substances contained in the resist into the immersion medium, and the performance of the resist film deteriorates, or the refractive index of the immersion medium locally changes or dissolves due to the eluted substance. It is conceivable that the substance adversely affects the lithography characteristics due to contamination of the lens surface. That is, problems such as deterioration in sensitivity, a resulting resist pattern having a T-top shape, and surface roughness and swelling of the resist pattern are expected.
As a means for solving such a problem, for example, it is conceivable to reduce the affinity of the resist film for the immersion medium. For example, as an immersion medium, an aqueous solvent such as water is currently being studied. Therefore, reducing the hydrophilicity of the resist film surface, that is, increasing the hydrophobicity (water repellency) causes the above-mentioned problem. It is estimated that it is effective for improvement.
However, in order to increase the hydrophobicity of the resist film, it is necessary to change the composition of the resist, and the change in the resist composition is usually accompanied by deterioration of lithography characteristics. Therefore, even if the hydrophobicity of the resist film is increased for use in immersion exposure, it is difficult to form a fine pattern on the resist film at a practically usable level.
The present invention has been made in view of the above circumstances, and can form a resist film having high hydrophobicity on the film surface and good lithography characteristics, and is suitable for immersion exposure. It is an object to provide a composition and a method for forming a resist pattern.

As a result of intensive studies, the present inventors have found that the above problems can be solved by using a specific resin containing a fluorine atom and an acrylic resin not containing a fluorine atom, thereby completing the present invention. It was.
That is, the first aspect of the present invention is a positive resist composition for immersion exposure 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 thing,
The resin component (A) has a main chain cyclic resin (A1) containing a fluorine atom and having no acid dissociable group, and a structural unit (a) derived from acrylic acid, and A positive resist composition for immersion exposure, comprising a resin (A2) containing no fluorine atom.
The second aspect of the present invention includes a step of forming a resist film on a substrate using the positive resist composition for immersion exposure according to the first aspect, a step of immersion exposure of the resist film, the resist film Is a resist pattern forming method including a step of developing a resist pattern to form a resist pattern.

In the present specification and claims, “structural unit” means a monomer unit constituting a polymer (resin).
The “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
A “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
“Exposure” is a concept that encompasses not only light irradiation but also radiation irradiation such as electron beam irradiation.

  According to the present invention, a positive resist composition for immersion exposure and a method for forming a resist pattern can be provided, which can form a resist film having high hydrophobicity on the film surface and good lithography characteristics, and suitable for immersion exposure. .

Hereinafter, the present invention will be described in more detail.
≪Positive resist composition for immersion exposure≫
The positive resist composition for immersion exposure of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid (hereinafter referred to as component (A)) and an acid generator component which generates an acid upon exposure. (B) (hereinafter referred to as component (B)).
In such a positive resist composition, the component (A) is insoluble in alkali before exposure, and when acid is generated from the component (B) by exposure, the acid increases alkali solubility of the component (A). Therefore, in the formation of a resist pattern, when selective exposure is performed on a resist film obtained using the positive resist composition, the exposed portion turns alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, a resist pattern can be formed by performing alkali development.

<(A) component>
[Resin (A1)]
The resin (A1) is a main chain cyclic resin containing a fluorine atom and having no acid dissociable group.
In the present specification and claims, the “acid-dissociable group” means a group dissociated by the action of an acid generated from the component (B) by exposure. For example, _-Q-NH-SO 2 -R ⁵ in later-described structural unit (a'1), -CO-O- R 7 in the structural unit (a'2), lactone-containing cyclic group in the structural unit (a2) The polar group-containing aliphatic hydrocarbon group in the structural unit (a3), the polycyclic aliphatic hydrocarbon group in the structural unit (a4), and the like are not included in the “acid-dissociable group”.
The acid dissociable group is not particularly limited as long as it is a group dissociated by the action of an acid generated from the component (B). For example, as an acid dissociable dissolution inhibiting group of a base resin for a chemically amplified resist, The suggested one can be used. Specific examples of the acid dissociable, dissolution inhibiting group include those similar to those exemplified as the acid dissociable, dissolution inhibiting group of the structural unit (a1) in the structural unit (a1) described later. here,
Here, “dissolution inhibition” in the acid dissociable dissolution inhibiting group means that the group has an action (dissolution inhibiting property) for inhibiting the solubility of the component (A) in alkali such as an alkali developer. . As described above, the acid dissociable, dissolution inhibiting group of the structural unit (a1) is an acid dissociable group that is dissociated by the action of an acid generated from the component (B). When the group is dissociated, the component (A) Increases the alkali solubility.
In the present invention, the “acid-dissociable group” may have a dissolution inhibiting property or may not have a dissolution inhibiting property.

In the present specification and claims, the term “main chain cyclic resin” means that the structural unit constituting the resin has a monocyclic or polycyclic ring structure, and is on the ring of the ring structure. It means that at least one, preferably two or more carbon atoms have a structural unit constituting the main chain (hereinafter sometimes referred to as main chain cyclic structural unit).
By containing the resin (A1) having such a structure, a resist film having high hydrophobicity on the film surface can be obtained. In addition, etching resistance is improved. The improvement in etching resistance is presumed to be because the carbon density is increased by having the main chain cyclic structural unit.

Examples of the main chain cyclic structural unit include structural units derived from polycycloolefins (polycyclic olefins), dicarboxylic acid anhydride-containing structural units listed in the structural unit (a′3) described later, and the like. .
Among these, it is preferable to have a structural unit derived from a polycycloolefin in the main chain because the etching resistance when used as a resist is particularly excellent.
As the structural unit derived from polycycloolefin, a structural unit having a basic skeleton represented by the following general formula (a ′) is preferable.

［式中、ａは０または１である。］

[Wherein, a is 0 or 1; ]

In the formula (a ′), a is 0 or 1, and is preferably 0 in consideration of industrial availability.
The “structural unit having a basic skeleton represented by the general formula (a ′)” is derived from the structural unit represented by the general formula (a ′) (that is, bicyclo [2.2.1] -2-heptene (norbornene). the induced structural units, and tetracyclo ^{[4.4.0.1 2.5 .1.} 7.10] -3- dodecene may be a structural unit) derived from, also described below structural unit ( As in a′1) to (a′3), the ring skeleton may have a substituent. That is, the “structural unit having the basic skeleton represented by the general formula (a ′)” includes the ring skeleton (bicyclo [2.2.1] -2-heptane or tetracyclo [4.4.0.1 ^{2]. .5,} 7.1, ^7.10 ] -3-dodecane) includes a structural unit in which part or all of the hydrogen atoms bonded to the carbon atom constituting the structural unit are substituted with atoms or substituents other than hydrogen atoms.

  The resin (A1) may have a structural unit other than the main chain cyclic structural unit, for example, the structural unit (a) (structural unit derived from acrylic acid) mentioned in the resin (A2) described later. For the effect of the present invention, it is preferable that the main chain cyclic structural unit is contained in the resin (A1) in an amount of 50 to 100 mol% with respect to all the structural units constituting the resin (A1). 80-100 mol% is more preferable.

・ Structural unit (a'1)
The resin (A1) preferably has a structural unit (a′1) represented by the following general formula (I) because it is excellent in the effects of the present invention.

［式（Ｉ）中、Ｒ^１〜Ｒ^４は、それぞれ独立に、水素原子、直鎖もしくは分岐鎖状のアルキル基、直鎖もしくは分岐鎖状のフッ素化アルキル基、または下記一般式（Ｉａ）で表される基（Ｉａ）であり、Ｒ^１〜Ｒ^４のうち少なくとも１つは前記基（Ｉａ）であり；ａは０または１である。］

[In the formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom, a linear or branched alkyl group, a linear or branched fluorinated alkyl group, or the following general formula (Ia) And at least one of R ^{1 to} R ⁴ is the group (Ia); a is 0 or 1; ]

［式（Ｉａ）中、Ｑは炭素数１〜５の直鎖または分岐鎖状のアルキレン基であり；Ｒ^５はフッ素化アルキル基である。］

Wherein (Ia), Q is a linear or branched alkylene group having 1 to 5 carbon atoms; R ⁵ is a fluorinated alkyl group. ]

The structural unit (a′1) represented by the general formula (I) is a structural unit having the basic skeleton represented by the general formula (a ′), as a substituent at a specific position on the ring. At least the group (Ia) represented by the general formula (Ia) is included.
In the present invention, the hydrophobicity of the resist film surface is improved by having such a structural unit. In addition, lithography properties are improved. The reason why such an effect is obtained is not clear, but by having the group (Ia), the effect of improving the hydrophobicity of the resist film by fluorine atoms can be obtained, and the alkali solubility of the resin (A1) can be improved. This is presumed to contribute to improvement of various lithography characteristics such as resolution and resist pattern shape.

In the formula (I), a is the same as a in the above formula (a ′).
The alkyl group of R ^{1 to} R ⁴ may be linear or branched, is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and an alkyl group having 1 to 5 carbon atoms. Groups are more preferred. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a pentyl group, an isopentyl group, and a neopentyl group.
The fluorinated alkyl group of R ^{1 to} R ⁴ is a group in which part or all of the hydrogen atoms of a linear or branched alkyl group are substituted with fluorine atoms. Examples of the alkyl group in the fluorinated alkyl group include the same alkyl groups as those described above for R ^{1 to} R ⁴ .
The fluorination rate of the fluorinated alkyl group (the ratio (%) of the number of fluorine atoms to the total number of hydrogen atoms and fluorine atoms in the fluorinated alkyl group) is preferably 10 to 100%, and preferably 30 to 100 % Is more preferable, and 50 to 100% is more preferable. When the fluorination rate is 10% or more, the effect of improving the hydrophobicity of the resist film surface is excellent.

  In general formula (Ia), the alkylene group of Q may be linear or branched, is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 8 carbon atoms, and 1 to 1 carbon atoms. More preferred is an alkylene group of 5. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a pentene group, an isopentene group, and a neopentene group. Among these, a linear alkylene group is preferable from the viewpoint of ease of synthesis, and a methylene group is particularly preferable.

The fluorinated alkyl group for R ⁵ is a group in which part or all of the hydrogen atoms of a linear, branched or cyclic alkyl group are substituted with fluorine atoms.
Examples of the linear or branched alkyl group include the same as the fluorinated alkyl groups of R ^{1 to} R ⁴ .
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 fluorination rate of the fluorinated alkyl group (the ratio (%) of the number of fluorine atoms to the total number of hydrogen atoms and fluorine atoms in the fluorinated alkyl group) is preferably 10 to 100%, and preferably 30 to 100 % Is more preferable, 50 to 100% is particularly preferable, and it is most preferable that 100%, that is, all hydrogen atoms are substituted with fluorine atoms. When the fluorination rate is 10% or more, the effect of improving the hydrophobicity of the resist film surface is excellent. Therefore, even if the ratio of the resin (A1) in the component (A) is small, a sufficient hydrophobicity improving effect can be obtained.
As the fluorinated alkyl group for R ⁵ , a linear or branched fluorinated alkyl group is preferable, a fluorinated alkyl group having 1 to 5 carbon atoms is more preferable, and in particular, all the hydrogen atoms of the alkyl group are fluorine atoms. A substituted perfluoroalkyl group is preferred. Specific examples of the perfluoroalkyl group include a trifluoromethyl group and a pentafluoroethyl group.

In the present invention, at least one of R ^{1 to} R ⁴ is the group (Ia) represented by the general formula (Ia), and the remaining 0 to 3 are a hydrogen atom, a straight chain or a branched chain. One or more selected from an alkyl group and a linear or branched fluorinated alkyl group. In the present invention, ^one of R ^{1 to} R ⁴ is preferably the group (Ia), and in particular, ^one of R ^{1 to} R ⁴ is the group (Ia) and the other three are hydrogen. It is preferably an atom.

  As the structural unit (a′1), a structural unit represented by general formula (Ib) shown below is particularly desirable.

In the formula (Ib), a is the same as described above.
p is an integer of 1 to 10, an integer of 1 to 8 is preferable, and 1 is most preferable.
q is an integer of 1 to 5, preferably an integer of 1 to 4, and most preferably 1.

As the structural unit (a′1), one type of structural unit may be used alone, or two or more types may be used in combination.
In the resin (A1), the proportion of the structural unit (a′1) is preferably 30 mol% or more, more preferably 40 mol% or more, and more preferably 45 mol with respect to the total of all the structural units constituting the resin (A1). % Or more is more preferable. The effect of this invention improves by setting it as 30 mol% or more.
The upper limit of the proportion of the structural unit (a′1) is not particularly limited and may be 100 mol%. For example, when other structural units such as the structural unit (a′2) described later are included, considering the balance with these structural units, it is preferably 95 mol% or less, more preferably 90 mol% or less, and 70 mol%. More preferred are:

  The monomer for deriving the structural unit (a′1) can be synthesized, for example, by the technique disclosed in US Pat. No. 6,420,503.

・ Structural unit (a'2)
The resin (A1) preferably has a structural unit (a′2) represented by the following general formula (II) in addition to the structural unit (a′1).
The structural unit (a′2) is a structural unit having the basic skeleton represented by the general formula (a ′). When a = 0, the 5-position on the ring, In which the fluorinated alkyloxycarbonyl group is bonded to the 8-position.
When the resin (A1) has the structural unit (a′2), the hydrophobicity of the resist film surface is further improved.

［式（ＩＩ）中、Ｒ^７はフッ素化アルキル基であり；ａは０または１である。］

[In formula (II), R ⁷ is a fluorinated alkyl group; a is 0 or 1; ]

In the formula (II), a is the same as a in the above formula (a ′).
Examples of the fluorinated alkyl group for R ⁷ include the same groups as those described above for the fluorinated alkyl group for R ⁵ in formula (Ia).
As the fluorinated alkyl group for R ⁷ , those in which part of the hydrogen atoms of the alkyl group are substituted with fluorine atoms are preferred. As such fluorinated alkyl groups, for example, one of the hydrogen atoms of the alkyl group is perfluoro And a group substituted with an alkyl group (a group in which an alkylene group is bonded to a perfluoroalkyl group).
As the fluorinated alkyl group, those having a fluorination rate of 30 to 90% are particularly preferable, and 50 to 80% are more preferable. When the fluorination rate is 30% or more, the effect of improving the hydrophobicity of the resist film surface is excellent. Further, when the fluorination rate is 90% or less, the lithography properties are improved.

As the structural unit (a′2), one type may be used alone, or two or more types may be used in combination.
In the resin (A1), the proportion of the structural unit (a′2) is preferably 5 to 60 mol%, more preferably 10 to 60 mol%, based on the total of all the structural units of the resin (A1), and 30 to 60 mol% is more preferable. By setting it to the lower limit value or more, the effect of having the structural unit (a′2) is excellent, and by setting it to the upper limit value or less, it is possible to balance with other structural units and improve the lithography characteristics.

  The monomer for deriving the structural unit (a′2) is, for example, a fluorinated alkyl ester of (meth) acrylic acid and cyclopentadiene or dicyclopentadiene, as described in JP-A-2000-235263. It can synthesize | combine by making it react by Diels-Alder reaction which is well-known reaction.

・ Other structural units (a'3)
The resin (A1) may contain a structural unit (a′3) other than the structural units (a′1) to (a′2) as long as the effects of the present invention are not impaired.
The structural unit (a ′ 3) is a structural unit that does not have an acid dissociable group and is not classified into the above structural units (a′1) to (a′2), and is a structural unit (a′1). The structural unit is not particularly limited as long as it is a structural unit derived from a monomer copolymerizable with a monomer that derives (a′2).
As the structural unit (a ′ 3), a structural unit derived from a known compound having an ethylenic double bond can be arbitrarily used depending on the purpose.

  More specifically, as the structural unit (a ′ 3), for example, a structural unit derived from acrylic acid such as the structural unit (a2) to the structural unit (a4) listed in the resin (A2) described later, a dicarboxylic acid Examples include an anhydride-containing structural unit, a structural unit derived from a polycycloolefin having no substituent, and a structural unit derived from a polycycloolefin having a polycyclic alicyclic group as a substituent.

  The acid anhydride-containing structural unit of dicarboxylic acid refers to a structural unit having a —C (O) —O—C (O) — structure. Examples of such include a structural unit containing a monocyclic or polycyclic cyclic acid anhydride, and more specifically, a monocyclic maleic anhydride shown in the following (a′31) Structural units derived from acids, structural units derived from polycyclic maleic anhydride represented by the following formula (a′32), structural units derived from itaconic acid represented by the following formula (a′33), etc. Is mentioned.

Examples of the structural unit derived from a polycycloolefin having no substituent include bicyclo [2.2.1] -2-heptene (norbornene), tetracyclo [4.4.0.1 ^2.5 . 1. ^7.10 ] -3-dodecene and the like.
In addition, as a structural unit derived from a polycycloolefin having a polycyclic alicyclic group as a substituent, as a substituent on the ring of the structural unit derived from a polycycloolefin having no substituent, Examples include structural units having a polycyclic group such as a tricyclodecanyl group, an adamantyl group, and a tetracyclododecanyl group.

In the resin (A1), the combination and ratio of the structural units such as the structural units (a′1) to (a′3) can be appropriately adjusted depending on required characteristics.
The resin (A1) preferably has at least the structural unit (a′1) because of excellent effects of the present invention. Examples of the resin include a unitary polymer containing the structural unit (a′1) and not containing the structural unit (a′2) (however, the structural unit (a′3) may be included), the structural unit And binary polymers containing (a′1) and the structural unit (a′2) (however, the structural unit (a′3) may be included).
When the resin (A1) is a binary polymer containing the structural unit (a′1) and the structural unit (a′2), the proportion (molar ratio) of each structural unit is excellent in the effect of the present invention. The structural unit (a′1) is preferably 40 to 95 mol% with respect to all structural units constituting the resin (A1) in that it is easy to control in the synthesis of the polymer and the polymer. It is more preferably mol%, most preferably 40 to 70 mol%, the structural unit (a′2) is preferably 5 to 60 mol%, and more preferably 10 to 60 mol%. Preferably, it is 30-60 mol% and most preferable.

  The resin (A1) is obtained, for example, by polymerizing a monomer that derives a predetermined structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). Can do.

The mass average molecular weight (Mw; polystyrene-converted mass average molecular weight by gel permeation chromatography (GPC). The same shall apply hereinafter) of the resin (A1) is not particularly limited, but is preferably 20000 or less, and more preferably 10,000 or less. When the Mw is 20000 or less, the effect of the present invention is improved, and in particular, lithography properties such as resolution are improved. Moreover, it is excellent in solubility in an organic solvent and the like, and it is possible to suppress the generation of foreign matters and development defects. Here, the foreign matter is a solid matter such as a particulate matter generated in the solution when the composition is used as a solution. The development defect is a general defect detected when a developed resist pattern is observed from directly above, for example, with a surface defect observation apparatus (trade name “KLA”) manufactured by KLA Tencor. Examples of such defects include scum, bubbles, dust, bridges (bridge structures between resist patterns), uneven color, and precipitates after development.
The lower limit of Mw is not particularly limited, but is preferably 2000 or more, and more preferably 4000 or more. When Mw is 4000 or more, there are advantages such as improved etching resistance, resist pattern swelling less during development, and pattern collapse less likely to occur.
The dispersity (Mw / Mn (number average molecular weight)) is preferably about 1.0 to 5.0, and more preferably 1.0 to 3.0.

In the component (A), the resin (A1) may be used alone or in combination of two or more.
The content of the resin (A1) in the component (A) is more preferably in the range of 0.1 to 50% by mass, further preferably 0.1 to 25% by mass, and 0.1 to 20% by mass. Is particularly preferable, and 0.1 to 10% by mass is most preferable. When the content of the resin (A1) is 0.1% by mass or more, the hydrophobicity of the surface of the resist film formed using the resist composition is improved, and the resistance to the immersion medium is improved. On the other hand, if it is 50% by mass or less, the balance with the resin (A2) becomes good and the lithography properties are improved.

[Resin (A2)]
The resin (A2) is a resin having the structural unit (a) derived from acrylic acid and containing no fluorine atom.
The resin (A2) is not particularly limited as long as it has a structural unit (a) derived from acrylic acid and does not contain a fluorine atom. Until now, a base resin for a chemically amplified positive resist 1 type, or 2 or more types of resin proposed as can be used.

[Structural unit (a)]
In the resin (A2), the structural unit (a) derived from acrylic acid does not contain a fluorine atom.
Here, in the present specification and claims, the “structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid.
“Acrylic acid” is a concept including acrylic acid (CH ₂ ═CHCOOH) in a narrow sense and derivatives in which part or all of the hydrogen atoms are substituted with other groups or atoms.
Derivatives of acrylic acid include, for example, α-substituted acrylic acid in which a substituent (atom or group other than a hydrogen atom) is bonded to the α-position carbon atom of narrowly defined acrylic acid, or hydrogen of the carboxy group of these acrylic acids Acrylic acid ester in which an atom is substituted with an organic group.
The “organic group” is a group containing a carbon atom, and the organic group in the acrylate ester is not particularly limited. For example, in the structural units listed in the structural units (a1) to (a4) described later, acrylic acid And groups bonded to the ester side chain of the ester (acid dissociable, dissolution inhibiting group, lactone-containing cyclic group, polar group-containing aliphatic hydrocarbon group, polycyclic aliphatic hydrocarbon group, etc.).
The α-position (α-position carbon atom) of acrylic acid is a carbon atom to which a carbonyl group is bonded, unless otherwise specified.
As the substituent of the α-substituted acrylic acid, a halogen atom (excluding a fluorine atom in the structural unit (a)), a lower alkyl group, a halogenated lower alkyl group (however, a fluorinated lower alkyl in the structural unit (a)) And the like are excluded).
In the structural unit (a), examples of the halogen atom as the substituent at the α-position include a chlorine atom, a bromine atom, and an iodine atom.
Specific examples of the lower alkyl group as a substituent at the α-position include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. And a lower linear or branched alkyl group.
Examples of the halogenated lower alkyl group as the substituent at the α-position include groups in which part or all of the hydrogen atoms of the lower alkyl group have been substituted with halogen atoms other than fluorine atoms.

In the structural unit (a), what is bonded to the α-position of acrylic acid is a hydrogen atom, a halogen atom other than a fluorine atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group). ), More preferably a hydrogen atom or a lower alkyl group, and most preferably a hydrogen atom or a methyl group in terms of industrial availability.
More specifically, examples of the structural unit (a) include structural units represented by the following general formula (a).

［式中、Ｒは水素原子、フッ素原子以外のハロゲン原子、低級アルキル基、またはハロゲン化低級アルキル基（ただしフッ素化低級アルキル基を除く。）であり、Ｘは水素原子であるか、またはフッ素原子を含まない１価の有機基である。］

[Wherein, R is a hydrogen atom, a halogen atom other than a fluorine atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group), and X is a hydrogen atom or fluorine It is a monovalent organic group containing no atoms. ]

The halogen atom, lower alkyl group or halogenated lower alkyl group of R (excluding the fluorinated lower alkyl group) is the halogen atom, lower alkyl group or halogenated lower alkyl group (provided as fluorine) as the substituent at the α-position. And the same as the above).
Examples of the organic group for X include the same as the above-described “organic group in acrylic ester”.

The resin (A2) preferably contains the structural unit (a) in a proportion of 50 to 100 mol%, based on the total of all the structural units constituting the resin (A2), and contains 70 to 100 mol%. It is more preferable. In particular, since the effect of the present invention is particularly excellent, the resin (A2) is preferably composed only of the structural unit (a) derived from acrylic acid.
Here, “consisting only of the structural unit (a)” means that the main chain of the resin (A2) is composed of only the structural unit (a) and does not include other structural units.

・ Structural unit (a1)
In the present invention, the resin (A2) preferably has a structural unit (a1) that does not have a fluorine atom and is derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group.
Here, the “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire resin (A2) insoluble in alkali before dissociation, and changes the entire resin (A2) to alkali-soluble after dissociation. If it is a thing, the thing proposed so far as an acid dissociable, dissolution inhibiting group of the base resin for chemically amplified resists can be used. Such an acid dissociable, dissolution inhibiting group is 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 dissociation property such as an alkoxyalkyl group Dissolution-inhibiting groups are widely known. The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

Here, “aliphatic” 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.
“Aliphatic branched” means having a branched structure having no aromaticity. The structure of the “aliphatic branched acid dissociable, dissolution inhibiting group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
As the aliphatic branched acid dissociable, dissolution inhibiting group, a tertiary alkyl group having 4 to 8 carbon atoms is preferable, and specific examples include a tert-butyl group, a tert-amyl group, and a tert-heptyl group. .

The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a halogen atom other than a fluorine atom, a halogenated lower alkyl group having 1 to 5 carbon atoms substituted with a halogen atom other than a fluorine atom, and an oxygen atom (= O). , Etc.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Specific examples of the aliphatic cyclic group may or may not be substituted with, for example, a lower alkyl group, a halogen atom other than a fluorine atom, or a halogenated alkyl group (excluding a fluorinated alkyl group). Examples thereof include a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as monocycloalkane, bicycloalkane, tricycloalkane, and tetracycloalkane. Specific examples thereof include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group. Specifically, 2-methyl-2 -Adamantyl group, 2-ethyl-2-adamantyl group, etc. are mentioned. Alternatively, in a structural unit represented by the following general formula (a1 ″), an aliphatic cyclic group such as an adamantyl group, such as a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—); And a group having a branched alkylene group having a tertiary carbon atom bonded thereto.

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

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

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

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

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

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

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

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

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

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

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

  As the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-0-1) and structural units represented by the following general formula (a1-0-2): Is preferably used.

［式中、Ｒは水素原子、フッ素原子以外のハロゲン原子、低級アルキル基、またはハロゲン化低級アルキル基（ただしフッ素化低級アルキル基を除く。）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 other than a fluorine atom, a lower alkyl group, or a halogenated lower alkyl group (excluding a fluorinated lower alkyl group); X ¹ represents an acid dissociable, dissolution inhibiting group; Show. ]

［式中、Ｒは水素原子、フッ素原子以外のハロゲン原子、低級アルキル基、またはハロゲン化低級アルキル基（ただしフッ素化低級アルキル基を除く。）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。］

In the formula, R represents a hydrogen atom, a halogen atom other than a fluorine atom, a lower alkyl group or a halogenated lower alkyl group (excluding fluorinated lower alkyl group.); The X ² represents an acid dissociable, dissolution inhibiting group Y; Y ² represents an alkylene group or an aliphatic cyclic group. ]

In general formula (a1-0-1), the halogen atom, lower alkyl group, or halogenated lower alkyl group of R is a halogen atom, lower alkyl group, or halogenated lower group that may be bonded to the α-position of the acrylate ester. It is the same as the alkyl group.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group, and examples thereof include 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).

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

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

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

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

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

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

（式中、Ｒは上記と同様であり、Ｒ^１１は低級アルキル基を示す。）

(In the formula, R is the same as above, and R ¹¹ represents a lower alkyl group.)

（式中、Ｒは上記と同様であり、Ｒ^１２は低級アルキル基を示し、ｈは１〜３の整数を表す）

(Wherein R is the same as above, R ¹² represents a lower alkyl group, and h represents an integer of 1 to 3)

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

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

  In the resin (A2), the proportion of the structural unit (a1) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, more preferably from 25 to 50 mol%, based on all structural units constituting the resin (A2). Is more preferable. By setting it to the lower limit value or more, a pattern can be easily obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a2)
In addition to the structural unit (a1), the resin (A2) preferably further has a structural unit (a2) that does not have a fluorine atom and is 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.
When the resin (A2) is used for forming a resist film, the lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate or has an affinity for a developer containing water. It is effective in raising.

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は上記と同様であり、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 as defined above, R ′ is a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is an integer of 0 or 1.] ]

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

  Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-3). Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the resin (A2) is preferably from 5 to 70 mol%, more preferably from 10 to 60 mol%, based on the total of all the structural units constituting the resin (A2). 50 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)
In addition to the structural unit (a1) or the structural units (a1) and (a2), the resin (A2) is an acrylic resin that does not have a fluorine atom and contains a polar group-containing aliphatic hydrocarbon group. It is preferable to contain the structural unit (a3) derived from an acid ester.
When the resin (A2) has 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. Contributes to improvement.
Examples of the polar group include a hydroxyl group, a cyano group, and a carboxy group, and 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 these, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyl group, a cyano group, or a carboxy group 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, preferred are a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), and the like. It is done.

（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の整数である。）

(In the formula, R is the same as above, j is an integer of 1 to 3, and k is an integer of 1 to 3.)

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group is bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.
j is preferably 1, and a hydroxyl group bonded to the 3rd position of the adamantyl group is particularly preferred.
In formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5th or 6th position of the norbornyl group.

As the structural unit (a3), one type may be used alone, or two or more types may be used in combination.
In the resin (A2), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, based on all the structural units constituting the resin (A2). More preferred is ˜25 mol%.

・ Structural unit (a4)
The resin (A2) 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 the structural unit (a4) does not contain a fluorine atom and is not classified into the structural units (a1) to (a3) described above. Many conventionally known materials can be used as those used for resist resins such as for use (preferably for ArF excimer laser).
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 for 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 have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

As the structural unit (a4), one type may be used alone, or two or more types may be used in combination.
When the structural unit (a4) is contained in the resin (A2), the structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 20 based on the total of all the structural units constituting the resin (A2). It is preferable to contain it in mol%.

In the present invention, the resin (A2) is preferably a copolymer having at least the structural units (a1), (a2) and (a3). Examples of such a copolymer include the structural unit (a1). , (A2) and (a3), the above-mentioned structural units (a1), (a2), (a3) and (a4).
In the present invention, the resin (A2) is particularly preferably one containing three structural units represented by the following general formula (A2-11).

［式中、Ｒ^４１，Ｒ^４３，Ｒ^４４はそれぞれ独立に水素原子、フッ素原子以外のハロゲン原子、低級アルキル基、またはフッ素原子以外のハロゲン原子で水素原子が置換された低級アルキル基（ハロゲン化低級アルキル基）であり、Ｒ^４２は低級アルキル基である。］

[Wherein R ⁴¹ , R ⁴³ and R ⁴⁴ are each independently a hydrogen atom, a halogen atom other than a fluorine atom, a lower alkyl group, or a lower alkyl group in which a hydrogen atom is substituted with a halogen atom other than a fluorine atom (halogenated). R ⁴² is a lower alkyl group. ]

In formula (A2-11), the lower alkyl group for R ⁴¹ , R ⁴³ , and R ^{44 is} the same as the lower alkyl group for R above. R ⁴¹ , R ⁴³ and R ⁴⁴ are preferably a hydrogen atom or a lower alkyl group, and more preferably a hydrogen atom or a methyl group.
The lower alkyl group for R ^{42 is the same as} the lower alkyl group for R above, and is preferably a methyl group or an ethyl group, and most preferably a methyl group.

  The resin (A2) 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).

The mass average molecular weight (Mw) of the resin (A2) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and most preferably 5000 to 20000. preferable. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

In the component (A), the resin (A2) may be used alone or in combination of two or more.
The content of the resin (A2) in the component (A) is preferably in the range of 50 to 99.9% by mass, more preferably 75 to 99.9% by mass, and 80 to 99.9% by mass. Further preferred. When the content of the resin (A2) is 99.9% by mass or less, the balance with the resin (A1) becomes good, and the hydrophobicity of the resist film surface formed using the resist composition is improved. The immersion medium resistance is improved. Moreover, the lithography characteristic improves that it is 50 mass% 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, 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.

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

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

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

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

  Moreover, as an onium salt type acid generator other than the acid generator represented by general formula (b-0), the compound represented by the following general formula (b-1) or (b-2) is mentioned, for example.

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

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

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. At least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may be substituted for the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, R ¹ ″ to R ³ ″ are 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 or branched alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ ″ and preferably has 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 carbon atoms. Most preferably, it is -10.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%. Particularly, all the hydrogen atoms are substituted with fluorine atoms. It is preferable because the strength of the acid is increased.
R ⁴ ″ is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

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

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

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

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

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

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

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

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

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

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

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

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

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

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

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

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

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

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

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

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

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzyl cyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope N-tenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile.
Also, an oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [chemical formula 18] to [chemical formula 19]), WO 2004 / 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 having a fluorinated alkyl sulfonate ion as an anion as the component (B).
The content of the component (B) in the positive resist composition for immersion exposure according to the present invention is 0.5 to 30 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the component (A). . By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<Optional component>
In the positive resist composition for immersion exposure according to the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as (D)) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Component)).
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. 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 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.

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 for immersion exposure of the present invention includes an organic carboxylic acid and a phosphorus oxo as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape and stability with time. At least one compound (E) selected from the group consisting of acids and derivatives thereof (hereinafter referred to as component (E)) can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of the phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
(E) A component may be used individually by 1 type and may use 2 or more types together.
(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 for immersion exposure according to the present invention may further contain a miscible additive as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

The positive resist composition for immersion exposure of the present invention can be produced by dissolving the material in an organic solvent (hereinafter sometimes referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. Conventionally, any one of known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used.
For example, lactones such as γ-butyrolactone;
Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone, methyl isoamyl ketone, 2-heptanone;
Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol and derivatives thereof;
Compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate 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;
Examples include aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene. be able to.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
Among these, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and EL are preferable.
Moreover, the mixed solvent which mixed PGMEA and the polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Moreover, when mix | blending PGME as a polar solvent, the mass ratio of PGMEA: PGME becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2, More preferably, it is 3: 7-7: 3.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
The amount of the component (S) used is not particularly limited, but is a concentration that can be applied to a substrate or the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 -20% by mass, preferably 5-15% by mass.

  The material can be dissolved in the component (S), for example, by simply mixing and stirring the above components by a usual method. If necessary, a disperser such as a dissolver, a homogenizer, or a three roll mill is used. It may be dispersed and mixed. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

As described above, the positive resist composition for immersion exposure of the present invention can form a highly hydrophobic resist film on the film surface. Also, the lithography properties are good, and when used as a resist in immersion exposure, a resist pattern can be formed without any practical problems.
The reason why such an effect is obtained is not clear, but the resin (A1) has a main chain cyclic structure containing a fluorine atom and no acid dissociable group, and the resin (A2) is a fluorine atom. When the resist film is formed using the positive resist composition for immersion exposure, the resin (A1) having relatively high hydrophobicity is near the outer surface of the resist film. On the other hand, it is assumed that the relatively hydrophilic resin (A2) is distributed inside the resist film. Then, the resin (A1) is distributed in the vicinity of the outer surface of the resist film, so that the hydrophobicity of the obtained resist film surface is improved (the receding angle is increased, for example) as compared with the case where the resin (A2) is used alone. It is presumed that good lithography characteristics are ensured by the resin (A2) being distributed inside the resist film together with a decrease in the falling angle.

Such a resist film has excellent resistance to an immersion medium, such as suppression of elution (substance elution) of components in the resist film into the immersion solvent when the immersion exposure process is performed. It is suitable for use.
That is, the resist film formed using the positive resist composition for immersion exposure according to the present invention has a contact angle with water [for example, static as compared to the case where only the resin (A2) is used as the component (A), for example. Contact angle (angle between the surface of the water droplet on the resist film in the horizontal state and the resist film surface), dynamic contact angle (contact angle when the water droplet starts to fall when the resist film is tilted. Contact angle (advance angle) at the end point in the fall direction and contact angle (retreat angle) at the end point in the fall direction.)] Or fall angle (water drops fall when the resist film is tilted) The inclination angle of the resist film when it begins to change is changed. For example, the receding angle increases, while the falling angle decreases.
In immersion exposure, as described above, the resist film comes into contact with an immersion solvent such as water during immersion exposure. Therefore, it is presumed that substance elution is affected by the characteristics of the resist film surface (for example, hydrophilicity / hydrophobicity).
In the present invention, by using the specific component (A), the hydrophobicity of the membrane surface is improved, so that the substance elution suppression effect is also improved. By increasing the hydrophobicity of the membrane surface, the immersion medium can be easily repelled from the membrane surface, the contact area and contact time between the membrane surface and the immersion medium can be reduced, and the influence of the immersion medium can be reduced. It is estimated that. For example, after the immersion exposure, the immersion medium can be quickly removed from the resist film surface when the immersion medium is removed.

Here, as shown in FIG. 1, the receding angle is such that when the plane 2 on which the droplet 1 is placed is gradually inclined, the droplet 1 starts to move (drop) on the plane 2. Is the angle θ ₁ formed by the upper end 1 a of the droplet 1 with respect to the plane 2, and the falling angle is the inclination angle θ ₂ of the plane 2 when the droplet 1 starts to move (drop) on the plane 2. is there.

In this specification, the receding angle and the falling angle are measured as follows.
First, a resist composition solution is spin-coated on a 6-inch diameter silicon substrate, and then heated at 90 ° C. for 90 seconds to form a resist film.
Next, the resist film is measured using a commercially available measuring apparatus such as AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.). Can do.

In the positive resist composition for immersion exposure according to 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 is preferably 55 to 150 °. More preferably, it is 55-130 degrees, It is most preferable that it is 60-100 degrees. 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.
In the positive resist composition for immersion exposure according to the present invention, the measured value of the falling angle in a resist film obtained using the resist composition is preferably 36 ° or less, and preferably 30 ° or less. More preferably, it is 25 ° or less, and most preferably 20 ° or less. When the falling angle is 36 ° or less, the substance elution suppression effect during immersion exposure is improved. Further, the measured value of the falling angle is preferably 10 ° or more, more preferably 12 ° or more, and further preferably 15 ° or more. When the falling angle is 10 ° or more, the lithography properties and the like are good.

  The size of the receding angle and the falling angle depends on the composition of the positive resist composition for immersion exposure, for example, the mixing ratio of the resin (A1) and the resin (A2) in the component (A), the structural unit (a3), etc. It can be adjusted by adjusting the proportion of each structural unit. For example, by setting the ratio of the resin (A1) in the component (A) to 1% by mass or more, the receding angle becomes significantly larger than the case where the resin (A2) is used alone, and the falling angle becomes smaller.

Furthermore, in the present invention, as described above, substance elution into the immersion solvent is suppressed. For this reason, it is possible to suppress the alteration of the resist film and the change in the refractive index of the immersion solvent. Therefore, by suppressing the change in the refractive index of the immersion solvent, the swell of the formed resist pattern and the line edge roughness (unevenness on the pattern side wall) are reduced, and the lithography characteristics such as the shape are improved. 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.
Moreover, according to the positive resist composition for immersion exposure of the present invention, a high-resolution resist pattern can be formed, for example, a resist pattern having a dimension of 120 nm or less can be formed.
Moreover, by using the positive resist composition for immersion exposure according to the present invention, it is possible to form a resist pattern having a good shape in which the generation of foreign matters and development defects is suppressed.
In the positive resist composition for immersion exposure according to the present invention, since the resin (A1) used as the component (A) does not have an acid dissociable group, for example, generally a positive resist composition is used. Compared to a resin (resin having an acid dissociable, dissolution inhibiting group) used as a base resin for a resist composition, there are also advantages such as easy synthesis and availability at low cost.

≪Resist pattern formation method≫
Next, the resist pattern forming method of the present invention will be described.
The resist pattern forming method of the present invention includes a step of forming a resist film on a substrate using the positive resist composition for immersion exposure of the present invention, a step of immersing the resist film, and developing the resist film. And a step of forming a resist pattern.

A preferred example of the method for forming a resist pattern of the present invention is shown below.
First, a positive resist composition for immersion exposure according to the present invention is applied onto a substrate such as a silicon wafer using a spinner and the like, and then pre-baked (post-apply bake (PAB) treatment) to form a resist film. .
At this time, an organic or inorganic antireflection film may be provided between the substrate and the resist composition coating layer to form a two-layer laminate.
Further, an organic antireflection film can be further provided on the resist film to form a two-layer laminate, and a three-layer laminate in which a lower antireflection film is further provided.
The antireflection film provided on the resist film is preferably soluble in an alkali developer.
The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the positive resist composition for immersion exposure to be used.

Next, liquid immersion lithography is selectively performed on the resist film obtained above through a desired mask pattern. At this time, the space between the resist film and the lens at the lowest position of the exposure apparatus is previously filled with a solvent (immersion medium) having a refractive index larger than that of air, and exposure (immersion exposure) is performed in this state.
The wavelength used for the exposure is not particularly limited, and can be performed using radiation such as an ArF excimer laser, a KrF excimer laser, or an F ₂ laser. The resist composition according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

As described above, in the forming method of the present invention, during exposure, the immersion film is filled between the resist film and the lens at the lowest position of the exposure apparatus, and exposure (immersion exposure) is performed in that state.
The immersion medium used at this time is preferably a solvent having a refractive index larger than that of air and smaller than that of a resist film formed using a positive resist composition for immersion exposure. 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, a silicon-based solvent, and a hydrocarbon-based solvent.

Specific examples of the fluorine-based inert _liquid, mainly composed of _{C 3 HC l2 F 5, C} 4 F 9 OCH 3, C 4 F 9 OC 2 H 5, C 5 H 3 F 7 , etc. A fluorine- Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C are preferable, and those having a boiling point of 80 to 160 ° C are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).

  The positive resist composition for immersion exposure of the present invention is particularly resistant to adverse effects due to water, and is excellent in sensitivity and resist pattern profile shape. Therefore, water is used as a solvent having a refractive index greater than that of air. Preferably used. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

  Next, after the immersion exposure step is completed, post-exposure heating (post-exposure baking (PEB)) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. In the water rinse, for example, water is dropped or sprayed on the surface of the substrate while rotating the substrate to wash away the developer on the substrate and the positive resist composition for immersion exposure dissolved by the developer. Then, drying is performed to obtain a resist pattern in which a resist film (a coating film of a positive resist composition for immersion exposure) is patterned into a shape corresponding to the mask pattern.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
<Examples 1-2 and Comparative Example 1>
Each component shown in Table 1 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] of Table 1 is a compounding quantity (mass part).
(A) -1 to (A) -5: polymers represented by the following formulas (A) -1 to (A) -5, respectively. In formulas (A) -1 to (A) -5, the numbers attached to the lower right of () indicate the proportion (mol%) of each structural unit.
(B) -1: Triphenylsulfonium nonafluoro-n-butanesulfonate.
(B) -2: (4-methylphenyl) diphenylsulfonium nonafluoro-n-butanesulfonate.
(D) -1: Triethanolamine.
(E) -1: salicylic acid.
(S) -1: PGMEA / EL = 80/20 (mass ratio) mixed solvent.

［Ｍｗ＝５０００、Ｍｗ／Ｍｎ＝１．５、プロメラス社製。］

[Mw = 5000, Mw / Mn = 1.5, manufactured by Promerus Corporation. ]

［Ｍｗ＝５０００、Ｍｗ／Ｍｎ＝１．５、プロメラス社製。］

[Mw = 5000, Mw / Mn = 1.5, manufactured by Promerus Corporation. ]

［Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝２．０。］

[Mw = 10000, Mw / Mn = 2.0. ]

［Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝１．８。］

[Mw = 10000, Mw / Mn = 1.8. ]

［Ｍｗ＝１００００、Ｍｗ／Ｍｎ＝１．６。］

[Mw = 10000, Mw / Mn = 1.6. ]

The following evaluation was performed using the obtained positive resist composition.
<Measurement of receding angle and falling angle>
The obtained positive resist composition was applied on a silicon wafer having a diameter of 8 inches using a spinner, pre-baked on a hot plate at 115 ° C. for 60 seconds, and dried to form a resist film having a thickness of 275 nm. Formed. One drop (50 μl) of pure water was dropped on the resist film, and then the receding angle and the falling angle were measured with the following apparatus and conditions (the receding angle and the falling angle before exposure).
<Device name>
AUTO SLIDING ANGLE: SA-30DM (Kyowa Interface Science Co., Ltd.)
AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.)
<Analysis software (included with the device)>
FAMAS

  Further, a resist film is formed in the same manner as described above, and an ArF excimer laser (193 nm) is applied to the resist film using an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60). Open frame exposure (exposure without using a mask) was carried out by using the resist film after exposure, and the falling angle and the receding angle were measured in the same manner as described above (the receding angle and the falling angle after exposure).

Table 2 shows the measurement results of the receding angle and the falling angle of the resist film before and after exposure.
As shown in these results, resin (A1) [(A) -1 or (A) -2] and resin (A2) [(A) -3 or (A) -4 to (A) -5] In Examples 1 to 3 in combination with the above, compared to Comparative Examples 1 and 2 using the resin (A2) alone, both the pre-exposure and post-exposure had a smaller sliding angle and a larger receding angle. . Further, the difference in the falling angle before and after the exposure and the difference in the receding angle before and after the exposure were small.

  In the above evaluation, the falling angle and the receding angle are for evaluating the hydrophilicity / hydrophobicity of the resist film. In Examples 1 to 3, the receding angle increases compared to Comparative Examples 1 and 2, and the falling angle It was confirmed that the hydrophobicity of the resist films of Examples 1 to 3 was improved as compared with Comparative Examples 1 and 2.

<Lithography characteristics>
An organic antireflective coating composition “ARC-29” (trade name, manufactured by Brewer Science Co., Ltd.) was applied onto an 8-inch silicon wafer using a spinner, baked on a hot plate at 205 ° C. for 60 seconds, and dried. As a result, an organic antireflection film having a thickness of 77 nm was formed. Then, each of the positive resist compositions of Examples 1 to 3 and Comparative Examples 1 and 2 was applied onto the antireflection film using a spinner, and prebaked on a hot plate at 115 ° C. for 60 seconds. (PAB) The resist film with a film thickness of 275 nm was formed by processing and drying.
Next, an ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S302 (Nikon Corp .; NA (numerical aperture) = 0.60, 2/3 annular illumination). . Then, PEB treatment was performed at 115 ° C. for 60 seconds, and further developed at 23 ° C. with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds, and then water was used for 30 seconds using pure water. Rinse and shake-dry.
As a result, a line-and-space resist pattern (hereinafter referred to as an L / S pattern) having a line width of 120 nm and a pitch of 240 nm could be formed in any of Examples 1 to 3 and Comparative Examples 1 and 2.
Moreover, when the L / S pattern obtained in this way was observed with a scanning electron microscope (SEM), L obtained using the positive resist compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were used. All the / S patterns were in good shape.

  From the above results, the resist film formed by using the positive resist composition for immersion exposure according to the present invention in which the resin (A1) and the resin (A2) are used in combination has high hydrophobicity and lithography characteristics. It was confirmed that it was as good as or better than a conventional chemically amplified positive resist composition. Therefore, since an aqueous medium such as water is mainly studied as an immersion medium, the positive resist composition for immersion exposure according to the present invention can form a resist film having high hydrophobicity and good lithography characteristics. Obviously, the object is suitable for immersion exposure.

<Examples 4 to 15 and Comparative Example 3>
Each component shown in Table 3 was mixed and dissolved to prepare a positive resist composition.

Each abbreviation in Table 3 has the following meaning. Moreover, the numerical value in [] of Table 3 is a compounding quantity (mass part).
(A) -6: a polymer having the following formula (A) -XY: x: y (molar ratio) = 81.7: 18.3, Mw = 4800, Mw / Mn = 1.48 (manufactured by Promerus) .
(A) -7: a polymer in the following formula (A) -XY where x: y (molar ratio) = 72.8: 27.2, Mw = 3700, Mw / Mn = 1.33 (manufactured by Promerus) .
(A) -8: a polymer having the following formula (A) -XY: x: y (molar ratio) = 47.5: 52.5, Mw = 4400, Mw / Mn = 1.93 (manufactured by Promerus) .
(A) -9: A polymer represented by the following formula (A) -9 and having Mw = 10000 and Mw / Mn = 2.1. In formula (A) -9, the number attached to the lower right of () indicates the proportion (mol%) of each structural unit.
(B) -2 and (D) -1 are the same as described above.
(S) -2: Mixed solvent of PGMEA / PGME = 60/40 (mass ratio).

Using the obtained positive resist composition, the receding angle and the falling angle were measured in the same manner as described above. The same equipment is used. The static contact angle was measured using the same procedure. The results are shown in Table 4. In Table 4, the type of the resin (A1) used ((A) -6 to (A) -8) and the content of the resin (A1) relative to the resin (A2) ((A) -9) (Hereinafter referred to as (A1) content (vs. (A2)), unit: mass%).
The static contact angle, the falling angle, and the receding angle are for evaluating the hydrophilicity / hydrophobicity of the resist film. In Examples 4 to 15, the static contact angle and the receding angle are higher than those in Comparative Example 3. It increased and the sliding angle decreased. From this result, it was confirmed that the hydrophobicity of the resist films of Examples 3 to 15 was improved as compared with Comparative Example 3. In particular, in the example using (A) -8 as the resin (A1), a significant hydrophobicity improving effect can be confirmed. For example, Examples 12 and 5 having a (A1) content (vs. (A2)) of 3.0% by mass. A remarkable effect was also observed in Example 13 of 0.0 mass% and Example 15 of 10.0 mass%.

<Lithography characteristics>
Using the positive resist composition obtained above, a resist pattern was formed in the same manner as in the above <lithography characteristics> except that a mask pattern having a hole inner diameter of 140 nm and a pitch of 280 nm as a target was used.
As a result, in any of the examples, a hole pattern having a hole inner diameter of 140 nm and a pitch of 280 nm could be formed.
At this time, the optimum exposure dose (Eop) (unit: mJ / cm ² (energy amount per unit area)), that is, the sensitivity at which a hole pattern having a hole inner diameter of 140 nm and a pitch of 280 nm is formed was determined. Moreover, the cross-sectional shape of the obtained hole pattern was observed by SEM. As a result, the lithography properties of Examples 13 and 14 were particularly excellent.

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

Claims (9)

A positive resist composition for immersion exposure comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) which generates an acid upon exposure,
The resin component (A) has a main chain cyclic resin (A1) containing a fluorine atom and having no acid dissociable group, and a structural unit (a) derived from acrylic acid; and A positive resist composition for immersion exposure, comprising a resin (A2) containing no fluorine atom. The positive resist composition for immersion exposure according to claim 1, wherein the resin (A1) has a structural unit (a′1) represented by the following general formula (I).

[In the formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom, a linear or branched alkyl group, a linear or branched fluorinated alkyl group, or the following general formula (Ia) And at least one of R ^{1 to} R ⁴ is the group (Ia); a is 0 or 1; ]

Wherein (Ia), Q is a linear or branched alkylene group having 1 to 5 carbon atoms; R ⁵ is a fluorinated alkyl group. ] The positive resist composition for immersion exposure according to claim 2, wherein the resin (A1) further comprises a structural unit (a'2) represented by the following general formula (II).

[In formula (II), R ⁷ is a fluorinated alkyl group; a is 0 or 1; ]   The positive resist composition for immersion exposure according to any one of claims 1 to 3, wherein a content of the resin (A1) in the resin component (A) is 0.1 to 50% by mass.   The resin (A2) has a structural unit (a1) derived from an acrylate ester having no fluorine atom and having an acid dissociable, dissolution inhibiting group. A positive resist composition for immersion exposure.   The positive resist for immersion exposure according to claim 5, wherein the resin (A2) further has a structural unit (a2) derived from an acrylate ester having no fluorine atom and containing a lactone-containing cyclic group. Composition.   The liquid immersion according to claim 5 or 6, wherein the resin (A2) further comprises a structural unit (a3) derived from an acrylate ester having no fluorine atom and containing a polar group-containing aliphatic hydrocarbon group. A positive resist composition for exposure.   The positive resist composition for immersion exposure according to any one of claims 1 to 7, comprising a nitrogen-containing organic compound (D).   A step of forming a resist film on a substrate using the positive resist composition for immersion exposure according to any one of claims 1 to 8, a step of immersing the resist film, and developing the resist film A resist pattern forming method including a step of forming a resist pattern.

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