JP5073839B2 - Resist composition for immersion exposure and method for forming resist pattern - Google Patents

Description

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

  Lithography is often 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 finer resist patterns 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 a fine pattern formation, the development of an exposure apparatus and a corresponding resist is the first.
As a resist, a chemically amplified resist that achieves high resolution while achieving high resolution, and can use catalytic reaction and chain reaction of acid generated by irradiation of radiation, has a quantum yield of 1 or more, and achieves high sensitivity. Is attracting attention and is being actively developed.
In a positive chemically amplified resist, a resin having an acid dissociable, dissolution inhibiting group is mainly used. As the acid dissociable, dissolution inhibiting group, for example, 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 are known. Further, 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.

On the other hand, in an 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. 248 nm KrF excimer laser light is used at about 0.30 to 0.15 μm, and 193 nm ArF excimer laser light is used at about 0.15 μm or less. 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 is reduced 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, for example, dissolution of substances contained in the resist into the immersion medium, and the performance deteriorates, or the refractive index of the immersion medium changes locally due to the eluted substances. 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 means for solving such a problem, for example, it is conceivable to increase the resistance of the resist film to the immersion medium (immersion medium resistance). At present, as an immersion medium, an aqueous solvent such as water is mainly studied. Therefore, it is estimated that increasing the hydrophobicity of the resist film is effective in improving the immersion medium resistance.
However, changing the composition of the resist in order to increase the hydrophobicity of the resist film usually deteriorates the lithography characteristics, so that it is difficult to achieve both immersion medium resistance and lithography characteristics.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a resist composition for immersion exposure and a method for forming a resist pattern, which can achieve both excellent immersion medium resistance and lithography characteristics.

As a result of intensive studies, the present inventors have found that the above problem can be solved by using an acrylic resin and a fluorine atom-containing resin having a specific blending amount, and have completed the present invention.
That is, the first aspect of the present invention is a resist composition for immersion exposure comprising a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) that generates an acid upon exposure. There,
The resin component (A) contains a resin (A1) containing a fluorine atom and a resin (A2) having a structural unit (a ′) derived from acrylic acid and containing no fluorine atom,
Content of the said resin (A1) in the said resin component (A) exists in the range of 0.1-20 mass%,
The resin (A1) is a resist composition for immersion exposure, which has a structural unit derived from acrylic acid having a fluorinated hydroxyalkyl group.
The second aspect of the present invention includes a step of forming a resist film on a substrate using the resist composition for immersion exposure according to the first aspect, a step of immersing the resist film, and developing the resist film. And a resist pattern forming method including a step of forming a resist pattern.

In the present invention, “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.
The “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.

  INDUSTRIAL APPLICABILITY According to the present invention, there are provided a resist composition for immersion exposure and a method for forming a resist pattern that can achieve both excellent immersion medium resistance and lithography characteristics.

It is a figure explaining a retreat angle and a fall angle.

Hereinafter, the present invention will be described in more detail.
≪Resist composition for immersion exposure≫
The resist composition for immersion exposure of the present invention comprises a resin component (A) whose alkali solubility is changed by the action of an acid (hereinafter referred to as component (A)) and an acid generator component (B) that generates an acid upon exposure. ) (Hereinafter referred to as component (B)).
In the present invention, the component (A) comprises a resin (A1) containing a fluorine atom and a resin (A2) having a structural unit (a ′) derived from acrylic acid and containing no fluorine atom. It is necessary that the content of the resin (A1) in the component (A) is in the range of 0.1 to 50% by mass.

The resist composition for immersion exposure of the present invention may be a negative resist composition, a positive resist composition, or a positive resist composition.
When the resist composition for immersion exposure of the present invention is a negative resist composition, the component (A) is an alkali-soluble resin, and a crosslinking agent (C) is further blended in the resist composition. In such a negative resist composition, when an acid is generated from the component (B) by exposure at the time of forming a resist pattern, the acid acts to cause crosslinking between the alkali-soluble resin and the crosslinking agent, thereby changing to alkali-insoluble.
As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is a good resist with little swelling. A pattern can be formed, which is preferable. Α- (Hydroxyalkyl) acrylic acid includes acrylic acid in which a hydrogen atom is bonded to the α-position carbon atom to which the carboxy group is bonded, and a hydroxyalkyl group (preferably having 1 carbon atom) in the α-position carbon atom. One or both of [alpha] -hydroxyalkylacrylic acids to which (5) hydroxyalkyl groups) are attached.
As the crosslinking agent (C), for example, it is usually preferable to use an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group because a good resist pattern with little swelling can be formed. The compounding amount of the crosslinking agent (C) is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

  When the resist composition for immersion exposure according to the present invention is a positive resist composition, the component (A) is a resin having an acid dissociable, dissolution inhibiting group and increasing alkali solubility due to the action of an acid. In such a positive resist composition, when an acid is generated from the component (B) by exposure at the time of resist pattern formation, the acid dissociates the acid dissociable, dissolution inhibiting group, whereby the component (A) becomes alkali-soluble. . Therefore, in the formation of the resist pattern, when the resist composition applied on the substrate is selectively exposed, the alkali solubility of the exposed portion increases and alkali development can be performed.

[Resin (A1)]
The resin (A1) is not particularly limited as long as it contains a fluorine atom. For example, one or two or more alkali-soluble resins or alkali-soluble resins that have been proposed as base resins for chemically amplified resists have been proposed so far. Possible resins can be used. When the former is used, a so-called negative resist composition is used, and when the latter is used, a so-called positive resist composition is obtained.

Since the resin (A1) is excellent in the effects of the present invention, it is preferable that the resin (A1) has a fluorinated hydroxyalkyl group in both the positive type and the negative type.
The “fluorinated hydroxyalkyl group” is a hydroxyalkyl group in which part of the hydrogen atoms of the alkyl group is substituted with a hydroxy group, and the remaining hydrogen atoms in the hydroxyalkyl group (in the hydroxy group of the alkyl group, Some or all of the hydrogen atoms that are not substituted are substituted by fluorine. In the fluorinated hydroxyalkyl group, the hydrogen atom of the hydroxy group is easily liberated by fluorination.
In the fluorinated hydroxyalkyl group, the alkyl group is preferably linear or branched. Although carbon number of the said alkyl group is not specifically limited, 1-20 are preferable, 4-16 are more preferable, and it is most preferable that it is 4-12. The number of hydroxy groups is not particularly limited, but is preferably one.
Among them, as a fluorinated hydroxyalkyl group, a fluorinated alkyl group and / or a fluorine atom is bonded to the carbon atom to which the hydroxy group is bonded (here, the α-position carbon atom of the hydroxyalkyl group). Those are preferred.
In particular, the fluorinated alkyl group bonded to the α-position is preferably a perfluoroalkyl group in which all of the hydrogen atoms of the alkyl group are substituted with fluorine.
In the present invention, it is particularly preferable that the resin (A1) has a group represented by the following general formula (I).

［式中、ｘは０〜５の整数であり、ｙおよびｚはそれぞれ独立して１〜５の整数である。］

[Wherein, x is an integer of 0 to 5, and y and z are each independently an integer of 1 to 5. ]

In the formula, x is preferably an integer of 0 to 3, and 0 or 1 is particularly preferable.
y and z are preferably integers of 1 to 3, with 1 being most preferred.

The resin (A1) preferably contains a structural unit (a) derived from acrylic acid in both the positive type and the negative type.
Here, in the present specification and claims, “acrylic acid” means acrylic acid in the narrow sense (CH ₂ ═CHCOOH) and derivatives in which part or all of the hydrogen atoms are substituted with other groups or atoms. A concept that includes
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 carboxyl group of these acrylic acids Acrylic esters in which atoms are substituted with organic groups.
The organic group in the acrylate ester is not particularly limited. For example, in the structural units listed in the structural units (a0) to (a4) described later, a group (fluorinated group) bonded to the ester side chain portion of the acrylate ester. A group having a hydroxyalkyl group and a monocyclic or polycyclic aliphatic cyclic group, an acid dissociable, dissolution inhibiting group, a group having a lactone ring, a polar group-containing aliphatic hydrocarbon group, a polycyclic fatty acid Group hydrocarbon group).
The α-position (α-position carbon atom) of acrylic acid is a carbon atom to which a carbonyl group is bonded, unless otherwise specified.
Examples of the substituent of α-substituted acrylic acid include a halogen atom, a lower alkyl group, a halogenated lower alkyl group and the like.
Examples of the halogen atom as the substituent at the α-position include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.
Specific examples of the lower alkyl group 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.
Bonded to the α-position of acrylic acid is preferably a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and is a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorinated lower alkyl group. More preferably, it is most preferably a hydrogen atom or a methyl group from the viewpoint of industrial availability.
“Structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid.
“A structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester.
Examples of the structural unit (a) include structural units represented by the following general formula (a).

［式中、Ｒは水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基であり、Ｘは水素原子または１価の有機基である］

[Wherein, R is a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and X is a hydrogen atom or a monovalent organic group]

Examples of the halogen atom, lower alkyl group or halogenated lower alkyl group for R include the same as the halogen atom, lower alkyl group or halogenated lower alkyl group as the substituent at the α-position.
Examples of the organic group for X include the same as the above-mentioned “organic group in acrylic ester”.

The resin (A1) 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 (A1), and contains 70 to 100 mol%. It is more preferable. In particular, since the effect of the present invention is particularly excellent, the resin (A1) is preferably composed of only the structural unit (a) derived from acrylic acid.
Here, “consisting only of the structural unit (a)” means that the main chain of the resin (A1) is composed of only the structural unit (a) and does not include other structural units.

In the present invention, the resin (A1) is a structural unit (a0) derived from an acrylate ester having a fluorinated hydroxyalkyl group and a monocyclic or polycyclic aliphatic cyclic group in the side chain portion. ).
Here, in the present specification and claims, the “side chain portion” means a portion that does not constitute the main chain, and as the structural unit (a0), X in the general formula (a) is fluorine. Examples thereof include a structural unit which is a group having both a converted hydroxyalkyl group and a monocyclic or polycyclic aliphatic cyclic group.
The term “aliphatic” in the “aliphatic cyclic group” is a relative concept with respect to aromaticity, and is defined to mean a group, compound, or the like that does not have aromaticity.
The aliphatic cyclic group may be monocyclic or polycyclic. “Monocyclic aliphatic cyclic group” means a monocyclic group having no aromaticity, and “polycyclic aliphatic cyclic group” means a polycyclic group having no aromaticity. Means a cyclic group.
An aliphatic cyclic group is a hydrocarbon group composed of carbon and hydrogen (alicyclic group), and a part of the carbon atoms constituting the ring of the alicyclic group is a heterogeneous group such as an oxygen atom, a nitrogen atom, or a sulfur atom. Heterocyclic groups and the like substituted with atoms are included. As the aliphatic cyclic group, an alicyclic group is preferable.
The aliphatic cyclic group may be either saturated or unsaturated, but is preferably saturated because it is highly transparent to ArF excimer laser and the like, and has excellent resolution and depth of focus (DOF). .
The aliphatic cyclic group preferably has 5 to 15 carbon atoms.
As a specific example of the aliphatic cyclic group, the monocyclic group includes a hydrogen atom substituted from a cycloalkane with a fluorinated hydroxyalkyl group (hereinafter the same), and two or more hydrogen atoms And the like except for. More specifically, a group in which one or more hydrogen atoms have been removed from cyclopentane or cyclohexane can be mentioned, and a group in which one hydrogen atom has been removed from cyclohexane is preferred.
Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. More specifically, a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane can be used.
Such a polycyclic group is appropriately selected from among many that have been proposed as constituting an acid dissociable, dissolution inhibiting group in a resin for a positive photoresist composition for ArF excimer laser process, for example. Can be used.
From the viewpoint of industrial availability, cyclohexane is preferred as the monocyclic group, and a group obtained by removing one or more hydrogen atoms from adamantane, norbornane, or tetracyclododecane is preferred as the polycyclic group, particularly from norbornane. Groups in which one or more hydrogen atoms have been removed are preferred.

  In the present invention, it is particularly preferable that the structural unit (a0) includes at least one structural unit selected from the group consisting of the following general formulas (a0-1) to (a0-3).

［式中、Ｒは水素原子、アルキル基、ハロゲン原子、ハロゲン化アルキル基であり；Ｒ^２１は（ｅ＋１）価の脂肪族環式基であり；Ｒ^２２、Ｒ^２３はそれぞれ独立に水素原子または１価の脂肪族環式基であって、Ｒ^２２およびＲ^２３の少なくとも１つは脂肪族環式基であり；ａ、ｄ、ｆはそれぞれ独立に０〜５の整数であり；ｂ、ｃはそれぞれ独立に１〜５の整数であり；ｅは２または３である。］

[Wherein, R represents a hydrogen atom, an alkyl group, a halogen atom or a halogenated alkyl group; R ²¹ represents an (e + 1) -valent aliphatic cyclic group; R ²² and R ²³ each independently represent a hydrogen atom or A monovalent aliphatic cyclic group, wherein at least one of R ²² and R ²³ is an aliphatic cyclic group; a, d and f are each independently an integer of 0 to 5; b, c Each independently represents an integer from 1 to 5; e is 2 or 3. ]

The structural unit represented by the general formula (a0-1) (hereinafter referred to as the structural unit (a0-1)) is a specific fluorinated hydroxyalkyl group [— (CH ₂ ) _a —C (C _b F _{2b + 1} ) (C _c F _{2c + 1} ) —OH] is a structural unit containing a norbornyl group having one. By having such a structural unit (a0-1), the effect of the present invention is further improved.

In formula (a0-1), examples of R include the same as R in formula (a) described above. R in the general formula (a0-1) is preferably a hydrogen atom or an alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.
a is an integer of 0 to 5, preferably an integer of 1 to 3, and most preferably 1.
b and c are each independently an integer of 1 to 5, preferably an integer of 1 to 3, and 1 is most preferable.
The structural unit (a0-1) has a 2-norbornyl group in which — (CH ₂ ) _a —C (C _b F _{2b + 1} ) (C _c F _{2c + 1} ) —OH is bonded to the 5th or 6th position of the norbornyl group. In particular, a structural unit in which R is a hydrogen atom or a methyl group, and a, b, and c are all 1 is also preferable from the viewpoint of effects, easy synthesis, and high etching resistance. .

The structural unit represented by the general formula (a0-2) (hereinafter referred to as the structural unit (a0-2)) includes two or three — (CH ₂ ) _d —C (C _b F _{2b + 1} ) (C _c It is a structural unit containing an aliphatic cyclic group having F _{2c + 1} ) —OH. By having such a structural unit (a0-2), the solubility in an alkali developer can be improved, and the effects of the present invention are further improved.

R in the general formula (a0-2) is the same as R in the general formula (a0-1). R in the general formula (a0-2) is preferably a hydrogen atom or an alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a methyl group.
b and c are the same as b and c in the above formula (a0-1).
d is an integer of 0 to 5, preferably 0 or 1, and most preferably 0.
e is 2 or 3, with 2 being most preferred.

R ²¹ is an (e + 1) -valent aliphatic cyclic group. Here, the “(e + 1) -valent aliphatic cyclic group” means a group obtained by removing (e + 1) hydrogen atoms bonded to carbon atoms constituting the ring skeleton of the aliphatic cyclic group.
Examples of the aliphatic cyclic group as R ²¹ include the same as those described above for the “aliphatic cyclic group”, which may be monocyclic or polycyclic. Since it is excellent in the effect of invention, it is preferable that it is monocyclic.
R ²¹ preferably has 3 to 20 carbon atoms, and more preferably 4 to 15 carbon atoms. More specifically, groups obtained by removing (e + 1) hydrogen atoms from cyclopentane, cyclohexane, adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like can be mentioned. In the present invention, R ²¹ is particularly preferably a group obtained by removing (e + 1) hydrogen atoms from cyclohexane.

The structural unit represented by the general formula (a0-3) (hereinafter referred to as the structural unit (a0-3)) has 1 or 2 hydrogen atoms in the methyl group — (CH ₂ ) _f —C (C _b F _{2b + 1} ) (C _c F _{2c + 1} ) —OH is a structural unit having a group substituted with —OH and one aliphatic cyclic group. By having such a structural unit (a0-3), the effect of the present invention is further improved.

R in the general formula (a0-3) is the same as R in the general formula (a0-1). R in the general formula (a0-3) is preferably a hydrogen atom or an alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a methyl group.
b and c are the same as b and c in the above formula (a0-1).
f is preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and 1 is most preferable.
R ²² and R ²³ are each independently a hydrogen atom or a monovalent aliphatic cyclic group, and at least one of R ²² and R ²³ is an aliphatic cyclic group. Examples of the aliphatic cyclic group for R ²² and R ²³ are the same as those described above for the “aliphatic cyclic group”, and may be monocyclic or polycyclic. From the viewpoint of excellent effects of the present invention, polycyclic is preferable.
The aliphatic cyclic group for R ²² and R ²³ preferably has 5 to 15 carbon atoms, and more preferably 6 to 12 carbon atoms. Among them, a group in which one or more hydrogen atoms are removed from adamantane, norbornane, tricyclodecane, or tetracyclododecane is preferable, and a group in which one or more hydrogen atoms are removed from norbornane is particularly preferable.
In the present invention, it is particularly preferable that one of R ²² and R ²³ is a hydrogen atom and the other is an aliphatic cyclic group.

The structural unit (a0) can be used alone or in combination of two or more.
In the resin (A1), the proportion of the structural unit (a0) is preferably 5 to 80 mol%, more preferably 5 to 70 mol%, based on the total of all the structural units constituting the resin (A1). 60 mol% is most preferred. By being more than the lower limit of the said range, the effect by containing a structural unit (a0) is fully acquired, and balance with another structural unit is favorable by being below an upper limit.

・ Structural unit (a1)
When the resist composition for immersion exposure according to the present invention is a positive resist composition, the resin (A1) has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group. Is preferred.
The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire resin (A1) insoluble in alkali before dissociation, and changes the entire resin (A1) to alkali soluble after dissociation. If it is a thing, what has been proposed as an acid dissociable dissolution inhibiting group of the base resin for chemically amplified resists can be used. Generally, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (meth) acrylic acid, or a group that forms a cyclic or chain alkoxyalkyl ester is widely known. . The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

Here, the tertiary alkyl ester is an ester formed by replacing the hydrogen atom of a carboxy group with a chain or cyclic alkyl group, and the carbonyloxy group (—C (O) —O). The structure in which the tertiary carbon atom of the chain or cyclic alkyl group is bonded to the oxygen atom at the terminal of-). 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.
The cyclic or chain alkoxyalkyl ester forms an ester by replacing the hydrogen atom of the carboxy group with an alkoxyalkyl group, and the carbonyloxy group (—C (O) —O—) A structure in which the alkoxyalkyl group is bonded to a terminal oxygen atom is shown. In this alkoxyalkyl ester, when an acid acts, a bond is cut between an oxygen atom and an alkoxyalkyl group.

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

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

(In the formula, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; X ¹ represents an acid dissociable, dissolution inhibiting group.)

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

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

In the 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 which 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 an alkoxyalkyl group, a tertiary alkyl ester type acid dissociable, dissolution inhibiting group, and the like. Acid dissociable, dissolution inhibiting groups are preferred. 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.
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 fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, an oxygen atom (= O), and the like.
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group is preferred.
Specific examples of such aliphatic cyclic groups include, for example, monocycloalkanes, bicycloalkanes, trialkyls which may or may not be substituted with a lower alkyl group, a fluorine atom or a fluorinated alkyl group. Examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as cycloalkane or tetracycloalkane. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Specific examples of the aliphatic branched acid dissociable, dissolution inhibiting group include a tert-butyl group and a tert-amyl group.
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 Examples include a 2-adamantyl group and a 2-ethyl-2-adamantyl group. Alternatively, as a structural unit represented by the following general formula, a group having an aliphatic cyclic group such as an adamantyl group and a branched alkylene group having a tertiary carbon atom bonded thereto can be given.

［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). ]

  Moreover, as said alkoxyalkyl group, group shown by the following general formula (p1) is preferable.

（式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐状のアルキル基または水素原子であり、Ｒ^１９は直鎖状、分岐状または環状のアルキル基である。または、Ｒ^１７とＲ^１９の末端が結合して環を形成していてもよい。）

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

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.
When Y ² is a divalent aliphatic cyclic group, it is the same as the description of the “aliphatic cyclic group” in the structural unit (a1) except that a group in which two or more hydrogen atoms are removed is used. 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 formulas (a1-1-1) to (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は水素原子、ハロゲン原子、低級アルキル基またはハロゲン化低級アルキル基を示し、Ｒ^１１は低級アルキル基を示す。）

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

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

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

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

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

  Examples of the structural unit preferably used in the present invention also include a structural unit in which the hydrogen atom of the hydroxyl group of the fluorinated hydroxyalkyl group is substituted with an acid dissociable, dissolution inhibiting group in the structural unit (a0). . More specifically, examples include structural units represented by the following general formulas (a1-5) to (a1-7), and among these, a structural unit represented by the formula (a1-6) is preferable.

In the formula, R, a, b, c, d, e, and f are the same as R, a, b, c, d, e, and f in the above formulas (a0-1) to (a0-3).
In the formula, X ³ is the same as X ¹ in the formula (a1-0-1). X ³ is preferably an alkoxyalkyl group, particularly preferably a group represented by the general formula (p1), and most preferably a methoxymethyl group.

  In the resin (A1), the proportion of the structural unit (a1) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, more preferably 25 to 60 mol%, based on all structural units constituting the resin (A1). 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)
The resin (A1) preferably has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group in addition to the structural unit (a1).
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. When only the lactone ring is present, it is called a monocyclic group. When it has another ring structure, it is called a polycyclic group regardless of the structure.
The lactone cyclic group of the structural unit (a2) increases the adhesion of the resist film to the substrate and the hydrophilicity with the developer when the resin (A1) is used for forming a resist film. It is effective.

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

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

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

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

R in the general formulas (a2-1) to (a2-5) is the same as 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 (a2-5), and at least one selected from general formulas (a2-1) to (a2-3). It is preferable to use more than one species. Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

In the resin (A1), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the resin (A1) is preferably from 5 to 70 mol%, more preferably from 10 to 60 mol%, based on the total of all structural units constituting the resin (A1). 60 mol% is more preferable. By making it the lower limit value or more, the effect of containing the structural unit (a2) can be sufficiently obtained, and by making it the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a3)
Resin (A1) contains a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural units (a1) and (a2). ) (Excluding the structural unit classified as the structural unit (a0)). By having the structural unit (a3), the hydrophilicity of the resin (A1) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom. A hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). . As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones.
Among them, a structural unit derived from an acrylate ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group, or an alkyl group is substituted with a fluorine atom Is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Among these polycyclic groups, there are groups in which two or more hydrogen atoms have been removed from adamantane, groups in which two or more hydrogen atoms have been removed from norbornane, and groups in which two or more hydrogen atoms have been removed from tetracyclododecane. Industrially preferable.

As the structural unit (a3), 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, X in the above formula (a) is a chain. A structural unit that is a linear (straight or branched) hydroxyalkyl group is preferred.
Moreover, when the said hydrocarbon group is a polycyclic group, the structural unit represented by the following formula (a3-1) and the structural unit represented by (a3-2) are mentioned as a preferable thing.

（式中、Ｒは前記に同じであり、ｊは１〜３の整数であり、ｋは１〜３の整数である。）

(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 (A1), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, based on all structural units constituting the resin (A1). More preferred is ˜25 mol%.

・ Structural unit (a4)
The resin (A1) may contain other structural units (a4) other than the structural units (a0) to (a3) as long as the effects of the present invention are not impaired.
The structural unit (a4) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a0) to (a3) described above. For example, a number of conventionally known resins can be used.
As the structural unit (a4), for example, a structural unit derived from an acrylate ester containing a non-acid-dissociable aliphatic polycyclic group is preferable. Examples of the polycyclic group include those exemplified in the case of the structural unit (a1), and for ArF excimer laser and KrF excimer laser (preferably for ArF excimer laser). A number of hitherto known materials can be used as the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may be substituted with a linear or branched alkyl group having 1 to 5 carbon atoms.
Specific examples of the structural unit (a4) include those represented by the following general formulas (a4-1) to (a4-5).

（式中、Ｒは前記と同じである。）

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

  When the structural unit (a4) is contained in the resin (A1), the structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 10% with respect to the total of all the structural units constituting the resin (A1). It is preferable to contain 20 mol%.

  In the present invention, the resin (A1) is preferably a copolymer having at least the structural units (a0) and (a1). Examples of the copolymer include the structural unit (a0) and the structural unit ( a copolymer comprising a1), a copolymer comprising structural units (a0), (a1) and (a2), a copolymer comprising the structural units (a0), (a1), (a2) and (a3) Etc. can be illustrated.

  In the present invention, the resin (A1) is particularly preferably a copolymer containing 2 to 4 kinds of structural units in the combinations represented by the following general formulas (A1-11) to (A1-15).

Wherein, ^{X 3} is the same as ^{X 3} in the formula (a1-6).
R, a, b, c, d, e, and f are the same as R, a, b, c, d, e, and f in the above formulas (a0-1) to (a0-3).
The lower alkyl group for R ^{9 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably an ethyl group.

Resin (A1) is a radical polymerization initiator such as azobisisobutyronitrile (AIBN) or dimethyl-2,2′-azobis (2-methylpropionate), which is a monomer derived from each structural unit. It can obtain by making it superpose | polymerize by well-known radical polymerization etc. using this.
In addition, the resin (A1) is used in combination with a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH at the time of the above-described polymerization. A —C (CF ₃ ) ₂ —OH group may be introduced into the. As described above, a copolymer introduced with a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom reduces development defects and LER (line edge roughness: uneven unevenness of line side walls). It is effective in reducing

The mass average molecular weight (Mw; polystyrene-converted mass average molecular weight by gel permeation chromatography) of the resin (A1) is not particularly limited, but is preferably 2000 to 30000, more preferably 2000 to 10000, and more preferably 3000 to 7000. preferable. By setting it within this range, a good dissolution rate in an alkaline developer can be obtained, which is preferable from the viewpoint of high resolution. Within this range, the lower the molecular weight, the better characteristics tend to be obtained.
The dispersity (Mw / Mn) is about 1.0 to 5.0, preferably 1.0 to 2.5.

In this invention, content of resin (A1) in (A) component needs to exist in the range of 0.1-50 mass%. When the content of the resin (A1) is 0.1% by mass or more, the resistance to the immersion medium is sufficient, and when it is 50% by mass or less, the balance with the resin (A2) becomes good. Thus, sufficient lithography characteristics can be obtained.
(A) As for content of resin (A1) in a component, 0.1-25 mass% is more preferable, 0.1-20 mass% is more preferable, 0.1-10 mass% is the most preferable.

[Resin (A2)]
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. One or two or more alkali-soluble resins or resins that can be alkali-soluble as proposed can be used. In the former case, a so-called negative type resist composition is used, and in the latter case, a so-called positive type resist composition.
Examples of the structural unit (a ′) include those that do not contain a fluorine atom among those listed as the structural unit (a) in the resin (A1).

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%. More preferably. 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 (a'1)
When the resist composition for immersion exposure according to the present invention is a positive resist composition, the resin (A2) is derived from an acrylate ester having no fluorine atom and containing an acid dissociable, dissolution inhibiting group. It is preferable to have a structural unit (a′1).
As the structural unit (a′1), the above-described structural unit (a1) that does not contain a fluorine atom can be used.
In the resin (A2), 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 (A2), the proportion of the structural unit (a′1) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, more preferably from 30 to 60, based on all the structural units constituting the resin (A2). More preferred is mol%. 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 (a'2)
The resin (A2) may have a structural unit (a′2) derived from an acrylate ester having no fluorine atom and containing a lactone-containing cyclic group, in addition to the structural unit (a′1). preferable.
As the structural unit (a′2), among the structural units (a2) described above, those not containing a fluorine atom can be used.
In the resin (A2), as the structural unit (a′2), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a′2) 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). 20-50 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 (a'3)
Resin (A2) has a fluorine atom and a polar group-containing aliphatic hydrocarbon in addition to structural unit (a′1) or in addition to structural units (a′1) and (a′2) It is preferable to have a structural unit (a′3) derived from an acrylate ester containing a group.
As the structural unit (a′3), among the structural units (a3) described above, those not containing a fluorine atom can be used.
As the structural unit (a′3), 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 (a′3) is preferably 5 to 50 mol% and more preferably 5 to 40 mol% with respect to all the structural units constituting the resin (A2). 5 to 25 mol% is more preferable.

・ Structural unit (a'4)
The resin (A2) may contain other structural units (a′4) other than the structural units (a′1) to (a′3) as long as the effects of the present invention are not impaired.
The structural unit (a′4) is not particularly limited as long as it does not contain a fluorine atom and is not classified into the above structural units (a′1) to (a′3). Many things conventionally known as what is used for resist resins, such as for ArF excimer lasers and for KrF excimer lasers (preferably for ArF excimer lasers), can be used.
As the structural unit (a′4), among the structural units (a4) described above, those not containing a fluorine atom can be used.
As the structural unit (a′4), one type may be used alone, or two or more types may be used in combination.
When the structural unit (a′4) is contained in the resin (A2), the structural unit (a′4) is preferably 1 to 30 mol% with respect to the total of all the structural units constituting the resin (A2), preferably Is preferably contained in an amount of 10 to 20 mol%.

  In the present invention, the resin (A2) is preferably a copolymer having at least the structural units (a′1), (a′2) and (a′3), and examples of such a copolymer include: A copolymer comprising the structural units (a′1), (a′2) and (a′3), the structural units (a′1), (a′2), (a′3) and (a ′); Examples thereof include a copolymer comprising 4).

  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”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^１０は低級アルキル基である。］

Wherein, R "is a hydrogen atom, a halogen atom other than a fluorine atom, a lower alkyl group or a lower alkyl group wherein a hydrogen atom with a halogen atom other than a fluorine atom is substituted, (halogenated lower alkyl group), R ¹⁰ Is a lower alkyl group.]

In formula (A2-11), the lower alkyl group for R ″ is the same as the lower alkyl group for R. As R ″, a hydrogen atom or a lower alkyl group is preferable, and a hydrogen atom or a methyl group is preferable.
The lower alkyl group for R ^{10 is the same as} the lower alkyl group for R ″, 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 that derives 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 addition, Mn shows a number average molecular weight.

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 80 to 99.9% by mass, and further 90 to 99.9% by mass. preferable. When the content of the resin (A2) is 50% by mass or more, good lithography characteristics can be obtained, and when it is 99.9% by mass or less, the balance with the resin (A1) is good and sufficient. High immersion medium resistance is obtained.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

（式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。）

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In the resist composition for immersion exposure according to the present invention, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof is used as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape, retention stability, etc. (E) (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.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and their esters, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Derivatives.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  The resist composition for immersion exposure according to the present invention further contains miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, and dissolution inhibition. An agent, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

The resist composition for immersion exposure according to the present invention can be produced by dissolving a 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, 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. -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.

According to the resist composition for immersion exposure of the present invention, both excellent immersion medium resistance and lithography characteristics can be achieved. The reason for this is not clear, but the properties of the resist film surface can be changed by using the resins (A1) and (A2) together as the component (A) and containing the resin (A1) in a specific ratio. It is estimated that.
That is, the resist film formed using the resist composition for immersion exposure according to the present invention has a static contact angle with respect to water (resist film is less than that when only the resin (A2) is used as the component (A). Horizontal contact angle), dynamic contact angle (contact angle when the water droplet starts to fall when the resist film is tilted. Contact angle (advance angle) at the front end point of the water droplet in the falling direction, There is a contact angle (retraction angle) at the end point behind the falling direction.), And the falling angle (the tilt angle of the resist film when the water droplet starts to fall when the resist film is tilted) changes. . For example, a static contact angle (hereinafter, simply referred to as a contact angle means a static contact angle) and a receding angle are increased. On the other hand, the falling angle is not necessarily influenced by the blending of the resin (A1), and may increase, decrease, or not change.
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 influenced by the characteristics (for example, hydrophilicity / hydrophobicity) of the resist film surface. In the present invention, it is presumed that by using the specific component (A), these characteristics are changed, whereby a substance film is hardly generated and a resist film capable of obtaining good lithography characteristics is formed. .

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 the present specification, the contact angle is 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, using the FACE contact angle meter CA-X150 type (product name, manufactured by Kyowa Interface Science Co., Ltd.), the resist film is brought into contact with the syringe provided in the apparatus (the syringe and the resist film). 2 μL of pure water is dripped when the contact angle is measured), and the contact angle at that time is measured.

  In this specification, the receding angle and the falling angle are obtained by forming a resist film in the same manner as described above, and then AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.), AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.). ) Etc. can be measured using a commercially available measuring device.

In the resist composition for immersion exposure according to the present invention, the measured value of the contact angle in a resist film obtained using the resist composition is preferably 60 degrees or more, more preferably 65 degrees or more, and 60 It is particularly preferable that the angle is ˜90 degrees. When the contact angle is 60 degrees or more, the substance elution suppression effect during immersion exposure is improved. The reason for this is not clear, but one of the main factors may be related to the hydrophobicity of the resist film. That is, since the immersion medium is water-based, such as water, it has high hydrophobicity. Therefore, after immersion exposure is performed, the immersion medium is quickly removed from the resist film surface after the immersion medium is removed. It is presumed that the fact that it can be removed has an effect. Moreover, the effect of this invention is favorable in a contact angle being 90 degrees or less.
For the same reason, in the resist composition for immersion exposure according to the present invention, the measured value of the receding angle in a resist film obtained using the resist composition is preferably 45 degrees or more, and is 50 to 150 degrees. It is more preferable that it is 55 to 130 degrees, and it is most preferable that it is 60 to 100 degrees.

  The size of the contact angle and the receding angle depends on the composition of the resist composition for immersion exposure, for example, the mixing ratio of the resin (A1) and the resin (A2) in the component (A) or the structural unit (a′3). It can be adjusted by adjusting the ratio or the like. 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 when the resin (A2) is used alone.

  As described above, in the present invention, substance elution into the immersion solvent is suppressed. For this reason, it is possible to suppress the deterioration of the resist film and the change in the refractive index of the immersion solvent. Therefore, by suppressing changes in the refractive index of the immersion solvent, the lithography characteristics such as pattern waviness, LER, and resist pattern shape are good, and contamination of the lens of the exposure apparatus can be reduced. Therefore, it is not necessary to take protective measures against these, and it can contribute to simplification of the process and the exposure apparatus.

≪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 resist composition for immersion exposure of the present invention, a step of immersing the resist film, developing the resist film, Forming a pattern.

A preferred example of the method for forming a resist pattern of the present invention is shown below.
First, after applying the immersion exposure resist composition of the present invention on a substrate such as a silicon wafer with a spinner or the like, pre-baking (post-apply baking (PAB) treatment) is performed 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 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 this state.
At this time, as the immersion medium, a solvent having a refractive index larger than the refractive index of air and having a refractive index of a resist film formed using the resist composition for immersion exposure is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, and a silicon-based solvent.

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

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

  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 resist composition for immersion exposure dissolved by the developer. Then, drying is performed to obtain a resist pattern in which the resist film (the coating film of the 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.
Resins used in the following examples and comparative examples were synthesized using the following monomers (1) to (7). That is, a monomer having the composition shown in Table 1 was dissolved in tetrahydrofuran (THF), a radical polymerization initiator V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixed solution was added to THF in another container for 6 hours. The solution was dropped and polymerized.
The obtained resin was subjected to GPC measurement, and the mass average molecular weight (Mw) and the degree of dispersion were determined. The results are also shown in Table 1.

  Resin (A) -2 ′ is further reacted with chloromethoxymethane to replace a part of hydroxyl groups in the resin (A) -2 ′ with a methoxymethyl group. 2 was obtained. When the resin (A) -2 was measured by proton NMR, 40 mol% of the hydroxyl groups of the resin (A) -2 'were substituted with methoxymethyl groups.

The structures of the resins (A) -1 to (A) -11 are shown below.
In the formula, the number attached to the lower right of () indicates the ratio (mol%) of each structural unit.
In Formula (A) -2, R represents a hydrogen atom or a methoxymethyl group, and 40% of all R in Resin (A) -2 is a methoxymethyl group.

Examples 1-40, Comparative Examples 1-5
The components shown in Tables 2 to 4 were mixed and dissolved to prepare a positive resist composition solution. Examples 1, 11, 16, 21, 26, 31 and 36 are reference examples.
Each abbreviation in Tables 2 to 4 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(B) -1: 4-methylphenyldiphenylsulfonium nonafluorobutanesulfonate.
(D) -1: Tripentylamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

The following evaluation was performed using the obtained positive resist composition solution.
<Measurement of contact angle>
Using a FACE contact angle meter CA-X150 type (product name, manufactured by Kyowa Interface Science Co., Ltd.), the contact angle, falling angle, and receding angle were measured according to the following procedure.
First, a positive resist composition solution was applied on an 8-inch silicon wafer using a spinner, and then heated at 95 ° C. for 90 seconds to form a 175 nm-thick resist film. Next, a horizontally disposed resist film is brought into contact with the syringe provided in the apparatus (when the syringe and the resist film are in contact with each other, 2 μL of pure water is dropped). The contact angle (to water) was measured (contact angle before exposure).
In addition, a resist film is formed in the same manner as described above, and open frame exposure (exposure without using a mask) is performed with an ArF excimer laser (193 nm) using a simple exposure apparatus VUVES4500 (manufactured by RISOTEC Japan Co., Ltd.). The contact angle (against water) was measured in the same manner except that (contact angle before exposure).
The results are also shown in Tables 2-4.

<Measurement of receding angle and falling angle>
The obtained positive resist composition solution was applied onto a silicon wafer having a diameter of 8 inches using a spinner, pre-baked on a hot plate at 110 ° C. for 90 seconds, and dried to obtain a resist film having a thickness of 175 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 using the following apparatus and conditions (the receding angle and the falling angle before exposure).
In addition, a resist film is formed in the same manner as described above, and open frame exposure (exposure without using a mask) is performed with an ArF excimer laser (193 nm) using a simple exposure apparatus VUVES4500 (manufactured by RISOTEC Japan Co., Ltd.). The receding angle and the falling angle were measured in the same manner except that (the receding angle and the falling angle after exposure).
The results are also shown in Tables 2-4.
<Device name>
AUTO SLIDING ANGLE: SA-30DM (manufactured by Kyowa Interface Science Co., Ltd.)
AUTO DISPENSER: AD-31 (manufactured by Kyowa Interface Science Co., Ltd.)
<Analysis software>
FAMAS

As shown in the following results, Examples 1 to 10 in which Resin (A) -1 corresponding to Resin (A2) and Resins (A) -2 to (A) -4 corresponding to Resin (A1) were used in combination. (Example 1 is a reference example) has a larger contact angle and receding angle than those of Comparative Example 1 in which resin (A) -1 was used alone before exposure, and the falling angle was the same as that of Comparative Example 1. It was equivalent or smaller than Comparative Example 1. In addition, in Examples 1 to 10 (Example 1 is a reference example), the contact angle and the receding angle were larger than those in Comparative Example 1 even after exposure.
Also, Examples 11 to 40 (Examples 11 and 40) in which Resin (A) -5 corresponding to Resin (A2) and Resins (A) -6 to (A) -11 corresponding to Resin (A1) were used in combination. 16, 21, 26, 31 and 36 are reference examples.) Before and after exposure, the contact angle and receding angle were larger than those of Comparative Example 5 in which resin (A) -5 was used alone. The sliding angle was equal to or smaller than that of Comparative Example 5 after exposure.

<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, the positive resist composition solution obtained above is applied onto an antireflection film using a spinner, pre-baked (PAB) at 120 ° C. for 90 seconds on a hot plate, and dried to obtain a film thickness of 175 nm. The resist film was formed.
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 120 ° C. for 90 seconds, followed by development with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution at 23 ° C. for 30 seconds, followed by water rinsing with pure water for 30 seconds. Then, it was shaken and dried to form a 120 nm line and space (1: 1) resist pattern (hereinafter referred to as L / S pattern).
When the L / S pattern thus obtained was observed by SEM, Examples 1 to 40 (Examples 1, 11, 16, 21, 26, 31 and 36 are reference examples) and Comparative Example 1 were used. As for, all showed the same lithography characteristics.
On the other hand, in the positive resist composition using only Comparative Example 3 using only (A) -2 and Comparative Example 3 using only (A) -3, although the resist pattern was resolved, The film loss was severe and poor. In the positive resist composition of Comparative Example 4 using only (A) -4, the resist pattern was not resolved.

<Measurement of eluate>
Using the positive resist composition solutions of Example 8 and Comparative Example 1, a resist film was formed in the same manner as described above. Next, using a VRC310S (manufactured by S.E.S. Co., Ltd.), a drop of pure water (150 μl) was moved at a constant linear velocity so as to draw a circle from the center of the wafer at room temperature (area) 221.56 cm ² ). Thereafter, the droplets are collected and analyzed by an analyzer Agilent-HP1100 LC-MSD (manufactured by Agilent Technologies), and the elution amount of the cation part (PAG +) and the anion part (PAG-) of the component (B) ( mol / cm ² ).

Further, a resist film is formed in the same manner as described above, and an open frame exposure (exposure without a mask) is performed with an ArF excimer laser (193 nm) using a simple exposure apparatus VUVES4500 (manufactured by RISOTEC JAPAN). Went.
Next, the exposed resist film was analyzed in the same manner as described above, and the elution amount (mol / cm ² ) of the cation part (PAG +) and the anion part (PAG−) of the component (B) was obtained. Table 5 shows.

As is clear from the above results, in the case where the positive resist composition of Example 8 in which the resin (A) -1 and the resin (A) -4 are used in combination, in the immersion medium (water) before and after the exposure treatment. The elution of the component (B) was suppressed, and the elution suppression effect was confirmed. On the other hand, when the positive resist composition of Comparative Example 1 using resin (A) -1 alone was used, the elution of the component (B) into the immersion medium (water) before and after the exposure treatment was significant. It was.
In the above evaluation, the amount of elution before exposure is for evaluating the amount of elution in the unexposed area when a resist pattern is formed by performing selective exposure, and the amount of elution after exposure is the elution in the exposed area. It is for evaluating the quantity. Therefore, since the substance elution into the immersion medium (water) was small before and after exposure, the positive resist composition of Example 8 was excellent in immersion medium resistance and was subjected to immersion exposure. It has been confirmed that it can be suitably used for immersion exposure used in a resist pattern forming method including a process.

Further, from the above results, the contact angle and the receding angle are increased by using the resin (A1) and the resin (A2) together, and the magnitude of the contact angle and the receding angle and the effect of suppressing the elution of the substance. It is clear that there is a correlation.
Therefore, the positive resist composition of the present invention is excellent in that the resin (A1) and the resin (A2) are used in combination, and the content in the component (A) of the resin (A1) is 0.1 to 50% by mass. It is clear that both the immersion medium resistance and the lithographic characteristics can be compatible and are suitable for immersion exposure.

Claims (12)

A resist composition for immersion exposure comprising a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) which generates an acid upon exposure,
The resin component (A) contains a resin (A1) containing a fluorine atom and a resin (A2) having a structural unit (a ′) derived from acrylic acid and containing no fluorine atom,
Content of the said resin (A1) in the said resin component (A) exists in the range of 0.1-20 mass%,
The resist composition for immersion exposure, wherein the resin (A1) has a structural unit derived from acrylic acid having a fluorinated hydroxyalkyl group.   The resist composition for immersion exposure according to claim 1, wherein the resin component (A) is a resin having an acid dissociable, dissolution inhibiting group and having increased alkali solubility by the action of an acid.   The resin (A1) has a structural unit (a0) derived from an acrylate ester having a fluorinated hydroxyalkyl group and a monocyclic or polycyclic aliphatic cyclic group in the side chain portion. The resist composition for immersion exposure according to claim 1 or 2. The resist composition for immersion exposure according to claim 3, wherein the structural unit (a0) comprises at least one structural unit selected from the group consisting of the following general formulas (a0-1) to (a0-3).

[Wherein, R represents a hydrogen atom, an alkyl group, a halogen atom or a halogenated alkyl group; R ²¹ represents an (e + 1) -valent aliphatic cyclic group; R ²² and R ²³ each independently represent a hydrogen atom or A monovalent aliphatic cyclic group, wherein at least one of R ²² and R ²³ is an aliphatic cyclic group; a, d and f are each independently an integer of 0 to 5; b, c Each independently represents an integer from 1 to 5; e is 2 or 3. ]   The resist composition for immersion exposure according to any one of claims 1 to 4, wherein the resin (A1) has a structural unit (a1) derived from an acrylate ester having an acid dissociable, dissolution inhibiting group.     The resist composition for immersion exposure according to claim 5, wherein the resin (A1) further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.   The resist composition for immersion exposure according to claim 5 or 6, wherein the resin (A1) further comprises a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.   The resin (A2) has a structural unit (a′1) derived from an acrylate ester having no fluorine atom and having an acid dissociable, dissolution inhibiting group. The resist composition for immersion exposure as described.   The resist for immersion exposure according to claim 8, wherein the resin (A2) further has a structural unit (a'2) derived from an acrylate ester having no fluorine atom and containing a lactone-containing cyclic group. Composition.   The resin (A2) further has a structural unit (a′3) derived from an acrylate ester having no fluorine atom and containing a polar group-containing aliphatic hydrocarbon group. Resist composition for immersion exposure.   The resist composition for immersion exposure according to any one of claims 1 to 10, comprising a nitrogen-containing organic compound (D).   The process of forming a resist film on a board | substrate using the resist composition for immersion exposure as described in any one of Claims 1-11, the process of immersing the said resist film, developing the said resist film, and developing a resist pattern A resist pattern forming method including a step of forming a film.

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