JP4633648B2 - Positive resist composition for immersion exposure and method for forming resist pattern - Google Patents

Description

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

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.
Up to now, as a base resin for chemically amplified resist, polyhydroxystyrene (PHS) having high transparency with respect to KrF excimer laser (248 nm) and a resin whose hydroxyl group is protected with an acid dissociable, dissolution inhibiting group (PHS resin) In addition, the carboxyl group of a resin (acrylic resin) having a structural unit derived from a (meth) acrylic acid ester having excellent transparency to an ArF excimer laser (near 193 nm) in the main chain is protected with an acid dissociable, dissolution inhibiting group. Resins and the like are generally used. 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.
In addition, examples of acid dissociable, dissolution inhibiting groups include acetal groups such as ethoxyethyl groups, tertiary alkyl groups such as tert-butyl groups, tert-butoxycarbonyl groups, and tert-butoxycarbonylmethyl groups. . For example, as a structural unit having an acid dissociable, dissolution inhibiting group in a resin component of a conventional ArF resist composition, as shown in the following Patent Document 1, (meta) such as 2-alkyl-2-adamantyl (meth) acrylate is used. A structural unit derived from a tertiary ester compound of acrylic acid 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 elution of substances contained in the resist into the immersion medium, and the performance of the resist film deteriorates, or the refractive index of the immersion medium locally changes or dissolves due to the eluted substance. It is conceivable that the substance adversely affects the lithography characteristics due to contamination of the lens surface. That is, problems such as deterioration in sensitivity, a resulting resist pattern having a T-top shape, and surface roughness and swelling of the resist pattern are expected.
As means for suppressing substance elution, 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. Therefore, it is difficult to achieve both suppression of substance elution and lithography characteristics.
The present invention has been made in view of the above circumstances, and provides a positive resist composition for immersion exposure and a resist pattern forming method that can suppress substance elution during immersion exposure and have excellent lithography properties. This is the issue.

The present inventors propose the following means in order to solve the above problems.
That is, the first aspect of the present invention includes a resin component (A) having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid, and an acid generator component (B) that generates an acid upon exposure. A positive resist composition for immersion exposure, wherein the resin component (A) is an acid dissociable solution comprising a main chain cyclic polymer (A1) and a chain-like tertiary alkyl group. Derived from a non-main chain cyclic polymer (A2) having a structural unit (a1-10) derived from an acrylate ester containing an inhibitory group and an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group A positive resist composition for immersion exposure, comprising: a non-main chain cyclic polymer (A3) having the structural unit (a1).

  The second aspect of the present invention includes a step of forming a resist film on a substrate using the positive resist composition for immersion exposure according to the first aspect, a step of immersion exposure of the resist film, the resist A resist pattern forming method including a step of developing a film to form a resist pattern.

In the present specification and claims, “structural unit” means a monomer unit (monomer unit) constituting a resin component (polymer).
“Exposure” is a concept that includes radiation exposure in general.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.

  INDUSTRIAL APPLICABILITY According to the present invention, there are provided a positive resist composition for immersion exposure and a method for forming a resist pattern, which can suppress substance elution during immersion exposure and have excellent lithography characteristics.

≪Positive resist composition for immersion exposure≫
The positive resist composition for immersion exposure according to the first aspect of the present invention has a resin component (A) (hereinafter referred to as component (A) having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid. And an acid generator component (B) that generates an acid upon exposure (hereinafter referred to as component (B)).
In the positive resist composition for immersion exposure of the present invention, since the component (A) has an acid dissociable, dissolution inhibiting group, it is insoluble in alkali before exposure, and the acid generated from the component (B) by exposure is When acting, the acid dissociable, dissolution inhibiting group is dissociated, whereby the alkali solubility of the entire component (A) is increased, and the alkali insoluble is changed to alkali soluble. Therefore, in the formation of a resist pattern, when selective exposure is performed on a resist film obtained using a positive resist composition for immersion exposure, the exposed portion turns alkali-soluble, while the unexposed portion is alkali-insoluble. Since it remains unchanged, alkali development can be performed.

<(A) component>
In the present invention, the component (A) comprises a main chain cyclic polymer (A1) (hereinafter sometimes referred to as polymer (A1)) and a chain-like tertiary alkyl group, which inhibits acid dissociable dissolution. A non-main chain cyclic polymer (A2) having a structural unit (a1-10) derived from an acrylate ester containing a group (hereinafter sometimes referred to as polymer (A2)), and a cyclic group A non-main chain cyclic polymer (A3) having a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group (hereinafter sometimes referred to as polymer (A3)). .
Hereinafter, the main chain cyclic polymer (A1), the non-main chain cyclic polymer (A2), and the non-main chain cyclic polymer (A3) will be described.

[Main chain cyclic polymer (A1)]
In the present specification and claims, the term “main chain cyclic polymer” means that the constitutional unit constituting the polymer has a monocyclic or polycyclic ring structure, and is on the ring of the ring structure. It means that at least one, preferably two or more carbon atoms have a constituent unit constituting the main chain (hereinafter referred to as main chain cyclic constituent unit).
By containing the polymer (A1) having such a structure, elution at the time of immersion exposure is suppressed, and further, the etching resistance when used as a resist is improved. This is presumably because the carbon density is increased by having the main chain cyclic structural unit.

Examples of the main chain cyclic structural unit include structural units derived from polycycloolefins (polycyclic olefins) and dicarboxylic acid anhydride-containing structural units listed in the structural unit (a′4) described later. . Among these, it is preferable to have a structural unit derived from a polycycloolefin in the main chain because the etching resistance when used as a resist is particularly excellent.
As the structural unit derived from polycycloolefin, a structural unit having a basic skeleton represented by the following general formula (a ′) is preferable.

［式中、ｓ’は０または１である。］

[Wherein, s ′ is 0 or 1. ]

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

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

・ Structural unit (a'1)
The polymer (A1) preferably has a structural unit (a′1) represented by the following general formula (a′1) because lithography properties such as resolution are good.

［式中、Ｒ^６１は低級アルキル基であり、ａ”は０または１であり、ｂ”は１〜３の整数である。］

[Wherein, R ⁶¹ represents a lower alkyl group, a ″ is 0 or 1, and b ″ is an integer of 1 to 3. ]

In the structural unit (a ′) derived from polycycloolefin, the structural unit (a′1) represented by the general formula (a′1) is in the 5-position on the ring (when a ″ = 0) or In the 8-position (when a ″ = 1), as a substituent, 1-alkyl (R ⁶¹ in formula (a′1): 2 or more carbon atoms) -1-cycloalkyl (5 to 8 carbon atoms) oxycarbonyl group It is what has.
The reason why the resolution is improved is that the 1-alkyl-1-cycloalkyl group portion of this substituent is an acid dissociable, dissolution inhibiting group, and the alkyl group of “1-alkyl” has 2 or more carbon atoms. For example, it is presumed that the acid dissociable, dissolution inhibiting group is easily dissociated as compared with the case where the alkyl group is a methyl group, thereby improving the resolution. Further, by having a cycloalkyl group which is a monocyclic alicyclic group, for example, the polymer (A1) has a lower hydrophobicity than when the acid dissociable, dissolution inhibiting group contains a polycyclic group such as adamantyl. (High hydrophilicity) When the polymer (A1) is blended into the resist composition, the affinity between the resist film obtained using the resist composition and the alkali developer increases, and the resulting resist pattern It is estimated that the resolution of the image is improved.
Moreover, the etching resistance of the resist pattern is improved as compared with the case where the acid dissociable, dissolution inhibiting group has a structure that does not include a ring such as a chain-like tertiary alkyl group.

In the formula (a′1), R ⁶¹ is a lower alkyl group, and may be a linear or branched alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, Examples include n-butyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group and the like. A methyl group or an ethyl group is preferable.
a ″ is 0 or 1, and is preferably 0 in consideration of easy industrial availability.
b ″ is an integer of 1 to 3, and is preferably 1 or 2 in consideration of easy synthesis and industrial availability.
In the present invention, it is particularly preferable that R ⁶¹ in the formula (a′1) is an ethyl group and b ″ is 2. That is, the acid dissociable, dissolution inhibiting group is a 1-ethyl-1-cyclohexyl group. It is preferable to have the above because the above effect is particularly excellent.

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 polymer (A1), the proportion of the structural unit (a′1) is preferably from 5 to 80 mol%, more preferably from 10 to 50 mol%, based on the total of all the structural units constituting the polymer (A1). Preferably, 10 to 30 mol% is more preferable. By setting it to the lower limit value or more, a pattern can be 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.

  A monomer for deriving the structural unit (a′1) is, for example, (meth) acrylic acid-1-alkyl (having 2 or more carbon atoms) -1-cycloalkyl as described in JP-A No. 2000-235263. It can be synthesized by reacting an ester having 5 to 8 carbon atoms with cyclopentadiene or dicyclopentadiene by a Diels-Alder reaction which is a known reaction.

・ Structural unit (a'2)
The polymer (A1) preferably further has a structural unit (a′2) represented by the following general formula (a′2) in addition to the structural unit (a′1).
When the polymer (A1) has the structural unit (a′2), lithography properties such as resolution are improved. This is because the hydrophilicity of the entire polymer (A1) is increased by the structural unit (a′2), and when the polymer (A1) is used as a resist composition, a resist film and an alkali obtained using the resist composition are used. This is presumably because the affinity with the developer is increased.

［式中、Ｒ^６２、Ｒ^６３はそれぞれ独立に水素原子または低級アルキル基であり、ａ”は０または１である。］

[Wherein R ⁶² and R ⁶³ each independently represent a hydrogen atom or a lower alkyl group, and a ″ is 0 or 1.]

In the structural unit (a ′) derived from polycycloolefin, the structural unit (a′2) represented by the general formula (a′2) is in the 5-position on the ring (when a ″ = 0) or A group obtained by removing one hydrogen atom from butyrolactone having groups R ⁶² and R ⁶³ is bonded to the 8-position (when a ″ = 1).
In the formula (a′2), a ″ is the same as a ″ in the above formula (a′1), and is preferably 0.
R ⁶² and R ⁶³ are each independently a hydrogen atom or a lower alkyl group, and it is preferable that both are hydrogen atoms in view of industrial availability.
The lower alkyl group for R ⁶² and R ⁶³ is a linear or branched alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, Examples include isobutyl group, pentyl group, isopentyl group, neopentyl group and the like.

As the structural unit (a′2), one type may be used alone, or two or more types may be used in combination.
In the polymer (A1), the proportion of the structural unit (a′2) is preferably 5 to 80 mol%, more preferably 10 to 50 mol%, based on the total of all the structural units of the polymer (A1). 10-30 mol% is more preferable. By setting it to the lower limit value or more, the effect of having the structural unit (a′2) is excellent, and by setting the upper limit value or less, it is possible to balance with other structural units.

・ Structural unit (a'3)
The polymer (A1) preferably has a structural unit (a′3) represented by the following general formula (a′3) in addition to the structural units (a′1) and (a′2). . By having the structural unit (a′3), the elution suppression effect during immersion exposure is further improved. This is presumably because the contact angle and the receding angle are further improved by having an alkali-soluble group, particularly an alkali-soluble group containing a fluorine atom. Further, by having the structural unit (a′3), resolution, substrate adhesion, and the like are also improved.

［式中、Ｒ^６４はアルカリ可溶性基を有する有機基であり、ａ”は０または１である。］

[Wherein R ⁶⁴ is an organic group having an alkali-soluble group, and a ″ is 0 or 1.]

In the formula (a′3), a ″ is the same as a ″ in the above formula (a′1), and is preferably 0.
R ⁶⁴ is an organic group having an alkali-soluble group.
Here, in the present specification and claims, the “organic group” means a group containing at least a carbon atom.
Examples of the alkali-soluble group in R ⁶⁴ include a group having a pKa comparable to that of a phenolic hydroxyl group, and a group having an alkali-soluble group such as an alcoholic hydroxyl group or a carboxy group. That is, it is a group having a small pKa (not particularly limited, but preferably a group having a pKa in the range of 6 to 12, for example).

More specifically, R ⁶⁴ includes, for example, an alcoholic hydroxyl group whose bonding position is not particularly limited; a hydroxyalkyl group in which the α-position carbon atom of the alcoholic hydroxyl group is substituted with an electron-withdrawing group; a carboxy group, and the like. . Among them, a hydroxyalkyl group in which the α-position carbon atom of the alcoholic hydroxyl group is substituted with an electron-withdrawing group or a carboxy group is preferable.
In the hydroxyalkyl group in which the α-position carbon atom of the alcoholic hydroxyl group is substituted with an electron-withdrawing group, examples of the electron-withdrawing group include a halogen atom or a halogenated alkyl group.
Examples of the halogen atom include a fluorine atom and a chlorine atom, and a fluorine atom is preferable.
In the halogenated alkyl group, the halogen atom is the same as the halogen atom. The alkyl group is preferably a lower alkyl group having, for example, about 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and most preferably a methyl group. Specific examples include a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a perfluoroethyl group, and the like, and a trifluoromethyl group is particularly preferable.
The number of electron-withdrawing groups is 1 or 2, preferably 2.

More specifically and preferably, the hydroxyalkyl group in which the carbon atom at the α-position of the alcoholic hydroxyl group is substituted with an electron-withdrawing group has a —CR ⁷¹ R ⁷² OH group, and R ⁷¹ and R ⁷² are: Each independently represents an alkyl group, a halogen atom, or a halogenated alkyl group, and at least one of them can be represented as an electron-withdrawing group selected from a halogen atom or a halogenated alkyl group.
The halogen atom or halogenated alkyl group here is the same as described above, and examples of the alkyl group include lower alkyl groups having 1 to 5 carbon atoms such as a methyl group, an ethyl group, and a propyl group.
Among these, those in which the electron-withdrawing group is a fluorine atom or a fluorinated alkyl group are preferable, and those in which R ⁷¹ and R ⁷² are both fluorinated alkyl groups are particularly preferable.

Among these, R ⁶⁴ is particularly preferably a group represented by the following general formula (a′31) because it has an excellent effect of suppressing substance elution during immersion exposure.

［式中、ｃ”は１〜５の整数であり、ｄ”およびｅ”はそれぞれ独立して１〜５の整数である。］

[Wherein c ″ is an integer of 1 to 5, and d ″ and e ″ are each independently an integer of 1 to 5.]

In formula (a′31), c ″ is an integer of 1 to 5, more preferably an integer of 1 to 3, and most preferably 1.
D ″ and e ″ are each independently an integer of 1 to 5, more preferably an integer of 1 to 3, and particularly those in which d ″ and e ″ are each 1 It is excellent in effect and is preferable.

As the structural unit (a′3), one type may be used alone, or two or more types may be used in combination.
In the polymer (A1) of the present invention, the proportion of the structural unit (a′3) is preferably 10 to 90 mol%, and preferably 20 to 80 mol% with respect to the total of all the structural units of the polymer (A1). More preferred is 50 to 70 mol%. By setting it to the lower limit value or more, the effect of having the structural unit (a′3) is excellent, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Other structural units (a'4)
The polymer (A1) may contain a structural unit (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 another structural unit not classified into the above structural units (a′1) to (a′3), and the structural units (a′1) to (a′3) are There is no particular limitation as long as it is a structural unit derived from a monomer copolymerizable with the derived monomer.
As the structural unit (a′4), a structural unit derived from a known compound having an ethylenic double bond can be arbitrarily used depending on the purpose.

  More specifically, as the structural unit (a′4), for example, a structural unit (a) derived from acrylic acid mentioned in the polymer (A2) described later, an anhydride-containing structural unit of dicarboxylic acid, and a substituent Examples thereof include structural units derived from polycycloolefins that do not have, structural units derived from polycycloolefins having a polycyclic alicyclic group as a substituent.

  The acid anhydride-containing structural unit of dicarboxylic acid refers to a structural unit having a —C (O) —O—C (O) — structure. Examples of such include structural units containing monocyclic or polycyclic cyclic acid anhydrides, and more specifically, monocyclic anhydrous represented by the following formula (a′41): Structural units derived from maleic acid, structural units derived from polycyclic maleic anhydride represented by the following formula (a′42), and structural units derived from itaconic acid represented by the following formula (a′43) Etc.

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

In the polymer (A1), the combination and ratio of the structural units such as the structural units (a′1) to (a′4) can be appropriately adjusted depending on required properties and the like. In view of lithography characteristics such as the shape of the resist pattern, etching resistance, and resolution, it is more preferable to have at least the structural units (a′1) and (a′3), and the structural unit (a′1). More preferably, it has ~ (a'3).
A binary polymer in which the polymer (A1) contains the structural unit (a′1) and the structural unit (a′3) and does not contain the structural unit (a′2) (however, the structural unit (a′4)) The ratio (molar ratio) of each structural unit is relative to all the structural units constituting the polymer (A1) in that the effect of the present invention and the control in the synthesis of the polymer are easy to control. The structural unit (a′1) is preferably 5 to 80 mol%, more preferably 10 to 60 mol%, and the structural unit (a′3) is preferably 5 to 95 mol%. 10 to 60 mol% is more preferable.
When the polymer (A1) is a ternary polymer containing the structural units (a′1) to (a′3) (however, the structural unit (a′4) may be included), each structural unit The proportion (molar ratio) of the structural unit (a′1) is preferably 5 to 80 mol% and preferably 10 to 50 mol% with respect to all the structural units constituting the polymer (A1). More preferably, the structural unit (a′2) is preferably 5 to 80 mol%, more preferably 10 to 50 mol%, and the structural unit (a′3) is 10 to 90 mol%. Is preferable, and it is more preferable that it is 20-80 mol%.
Thereby, the suppression effect of substance elution at the time of immersion exposure is further improved, and lithography characteristics such as etching resistance, resist pattern shape, and resolution are also improved.

  A preferred specific example of the polymer (A1) is a polymer (A11) represented by the following general formula (A1-11). This polymer (A11) can suppress elution of substances from the resist film during immersion exposure, is excellent in etching resistance and resist pattern shape, is excellent in lithographic properties such as resolution, and further adheres to the substrate. Excellent in pattern collapse.

  The polymer (A1) can be obtained, for example, by polymerizing a monomer related to each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). .

The polymer (A1) has a mass average molecular weight (Mw; polystyrene-reduced mass average molecular weight by gel permeation chromatography, the same shall apply hereinafter) of preferably 20000 or less, and more preferably 15000 or less. When the mass average molecular weight is 20000 or less, there are advantages such as excellent etching resistance, resist pattern swelling during development, and pattern collapse.
The lower limit is not particularly limited, but is preferably 3000 or more and more preferably 5000 or more in consideration of resolution, solubility in an organic solvent, and the like.
Further, the dispersity (Mw / Mn) of the polymer (A1) is preferably 1.0 to 5.0, preferably 1.0 to
3.0 is more preferable, and 1.0 to 2.0 is most preferable. In addition, Mn shows a number average molecular weight.

In the component (A), the polymer (A1) may be used alone or in combination of two or more.
(A) As for content of the polymer (A1) in a component, 1-50 mass% is preferable, 3-40 mass% is more preferable, 5-20 mass% is further more preferable. By being more than the lower limit, the elution suppression effect at the time of immersion exposure is improved. Furthermore, the etching resistance when used as a resist is improved. By being below the upper limit, a balance with other polymers (such as non-main chain cyclic polymers) can be achieved.

[Non-main chain cyclic polymer (A2)]
In the present invention, the non-main chain cyclic polymer (A2) has a structural unit (a1-10) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group. .
The polymer (A2) preferably has no structural unit (a1-10 ′) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group.
The polymer (A2) preferably further has a structural unit (a2-10) derived from an acrylate ester containing a lactone-containing cyclic group.
The polymer (A2) preferably further has a structural unit (a3-10) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.

Here, in the present specification and claims, the “non-main chain cyclic polymer” means that the polymer is not the “main chain cyclic polymer” described above. That is, it means that the carbon atom constituting the main chain of the non-main chain cyclic polymer does not include the carbon atom constituting the ring.
Among the non-main chain cyclic polymers in the present invention, those having a structural unit (a) derived from acrylic acid in the main chain are preferred because the effects of the present invention are improved.
Here, “acrylic acid” has a concept including acrylic acid (CH ₂ ═CHCOOH) in a narrow sense and derivatives in which part or all of the hydrogen atoms are substituted with other groups or atoms.
Derivatives of acrylic acid include, for example, α-substituted acrylic acid in which a substituent (atom or group other than a hydrogen atom) is bonded to the α-position carbon atom in narrowly defined acrylic acid, and hydrogen of the carboxy group of these acrylic acids Examples include acrylic acid esters in which atoms are substituted with organic groups, and acrylic acid esters are particularly preferable.
The α-position (carbon atom at the α-position) in acrylic acid indicates 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.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
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.
In addition, it is preferable that a hydrogen atom, a halogen atom, a lower alkyl group, or a halogenated lower alkyl group is bonded to the α-position of the acrylate ester, and a hydrogen atom, a fluorine atom, a lower alkyl group, or a fluorinated lower group. An alkyl group is more preferable, and a hydrogen atom or a methyl group is most preferable in terms of industrial availability.
The “structural unit derived from acrylic acid” means a structural unit that is 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.

  Preferred examples of the structural unit (a) derived from acrylic acid 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 represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and X represents 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.
The monovalent organic group of X is not particularly limited. For example, in the constituent units constituting the polymers (A2) and (A3) described later, a group (acid dissociation property) bonded to the ester side chain portion of the acrylate ester A dissolution inhibiting group, a group having a lactone ring, a polar group-containing aliphatic hydrocarbon group, a polycyclic aliphatic hydrocarbon group, and the like.

In the present invention, the polymer (A2) may contain the structural unit (a) in a proportion of 50 mol% or more with respect to the total of all the structural units constituting each non-main chain cyclic polymer. Preferably, it contains 70 mol% or more. Especially, since it is especially excellent in the effect of this invention, it is most preferable that this polymer (A2) consists only of structural unit (a) induced | guided | derived from acrylic acid.
The phrase “consisting only of the structural unit (a)” means that the main chain of the polymer (A2) is composed of only the structural unit (a) and does not include other structural units.

・ Structural unit (a1-10)
The polymer (A2) has a structural unit (a1-10) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group. By having the structural unit (a1-10), lithography properties such as a resist pattern shape are improved.
Here, in the present specification and claims, the “tertiary alkyl group” refers to a monovalent saturated hydrocarbon group having a tertiary carbon atom. Therefore, the “acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group” means an acid dissociable, dissolution inhibiting group composed of a branched alkyl group and having no cyclic group.

  Preferred examples of the structural unit (a1-10) include the structural unit (a1-11) represented by general formula (a1-0-1) shown below because lithography characteristics can be further improved. It is done.

［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は炭素数４以上の鎖状の第三級アルキル基からなる酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹¹ represents an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group having 4 or more carbon atoms. . ]

  In general formula (a1-0-1), R represents a hydrogen atom, a halogen atom, a lower alkyl group, or a halogenated lower alkyl 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. R is most preferably a methyl group.

In the general formula (a1-0-1), R ¹¹ is an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group having 4 or more carbon atoms.
The acid dissociable, dissolution inhibiting group of R ¹¹ has an alkali dissolution inhibiting property that makes the whole polymer (A2) insoluble in alkali before dissociation, and changes the whole polymer (A2) to alkali soluble after dissociation. It is.
R ¹¹ is not particularly limited as long as it is a chain-like tertiary alkyl group having 4 or more carbon atoms, and has been proposed as an acid dissociable, dissolution inhibiting group for base resins for chemically amplified resists. Can be used.
Here, in the present invention, “an acid dissociable, dissolution inhibiting group composed of a chain tertiary alkyl group having 4 or more carbon atoms” is composed of a branched alkyl group having a total carbon number of 4 or more, and is cyclic. It means an acid dissociable, dissolution inhibiting group having no group.
R ¹¹ has 4 or more carbon atoms, preferably 4 to 10 carbon atoms, more preferably 4 to 8 carbon atoms, and most preferably 5 to 7 carbon atoms.

  Among the structural units (a1-11), preferable are structural units (a1-11-0) represented by general formula (a1-0-2) shown below because lithography properties are further improved. Is mentioned.

［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^ａ〜Ｒ^ｃはそれぞれ独立して炭素数１〜５の低級アルキル基である。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{a to} R ^c each independently represents a lower alkyl group having 1 to 5 carbon atoms. ]

In formula (a1-0-2), R is the same as R in formula (a1-0-1).
R ^{a to} R ^c are each independently a lower alkyl group having 1 to 5 carbon atoms.
The lower alkyl group may be linear or branched. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Among them, a methyl group, an ethyl group, and a propyl group are preferable.
The total carbon number of R ^{a to} R ^c is 3 or more, preferably 3 to 9, more preferably 3 to 7, and most preferably 4 to 6.
As the structural unit (a1-11-0), since the effects of the present invention are excellent, R ^{a to} R ^c are all linear alkyl groups, and R ^{a to} R ^c have the same carbon number. In particular, R ^{a to} R ^c are all linear and more preferably alkyl groups having the same carbon number, and R ^{a to} R ^c are all ethyl groups (tert-heptyl group). ) Is most preferred.

  Specific examples of preferable structural units as the structural unit (a1-1-11-0) are shown below.

Among these, the structural units represented by the chemical formulas (a1-11-5) and (a1-11-6) are more preferable, and the structural unit represented by the chemical formula (a1-11-5) is most preferable.
In the polymer (A2), as the structural unit (a1-10), one type of structural unit may be used alone, or two or more types may be used in combination.
10-80 mol% is preferable with respect to the sum total of all the structural units which comprise a polymer (A2), and, as for the ratio of the structural unit (a1-10) in a polymer (A2), 20-70 mol% is more. Preferably, 25 to 50 mol% is more preferable, and 30 to 45 mol% is most 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. Moreover, by setting it as the said range, the effect of this invention, especially a favorable resist pattern shape will become easy to be obtained, and a lithography characteristic will improve.

・ Structural unit (a2-10)
The polymer (A2) according to the present invention preferably has a structural unit (a2-10) derived from an acrylate ester containing a lactone-containing cyclic group in addition to the structural unit (a1-10).
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.
When the polymer (A2) is used for forming a resist film, the lactone cyclic group of the structural unit (a2-10) can increase the adhesion of the resist film to the substrate or can be used with a developer containing water. It is effective in increasing affinity.

As the structural unit (a2-10), 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 (a2-10) 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 (a1-10).
The lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1-10).
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

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

In the polymer (A2), as the structural unit (a2-10), one type of structural unit may be used alone, or two or more types may be used in combination.
5-60 mol% is preferable with respect to the sum total of all the structural units which comprise a polymer (A2), and the ratio of the structural unit (a2-10) in a polymer (A2) is 10-50 mol% more. Preferably, 20-50 mol% is more preferable. The effect by containing a structural unit (a2-10) is fully acquired by setting it as more than a lower limit, and it can balance with another structural unit by setting it as an upper limit or less.

・ Structural unit (a3-10)
The polymer (A2) according to the present invention is a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1-10) or in addition to the structural units (a1-10) and (a2-10). It is preferable to have a structural unit (a3-10) derived from an acrylate ester containing By having the structural unit (a3-10), the hydrophilicity of the polymer (A2) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. To do.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which part of the hydrogen atoms of the alkyl group is substituted with a fluorine atom, and a hydroxyl group is particularly preferable.
Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group) and a polycyclic aliphatic hydrocarbon group (polycyclic group). It is done. 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 (a3-10), 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, hydroxyethyl ester of acrylic acid The structural unit derived from is preferable, and when the hydrocarbon group is a polycyclic group, the structural unit represented by the following formula (a3-1), the structural unit represented by the following formula (a3-2), A structural unit represented by the following formula (a3-3) is preferable.

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

[Wherein, R is as defined above, j is an integer of 1 to 3, k is an integer of 1 to 3, t ′ is an integer of 1 to 3, and l is an integer of 1 to 5] And s is an integer of 1 to 3. ]

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

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

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

In the polymer (A2), as the structural unit (a3-10), one type of structural unit may be used alone, or two or more types may be used in combination.
In the polymer (A2), the proportion of the structural unit (a3-10) is preferably 5 to 50% by mole, and 5 to 40% by mole with respect to all the structural units constituting the polymer (A2). More preferably, 5-25 mol% is further more preferable. The effect by containing a structural unit (a3-10) is fully acquired by setting it as more than a lower limit, and it can balance with another structural unit by setting it as an upper limit or less.

・ Other structural units (a4-10)
The polymer (A2) may contain other structural units (a4-10) other than the structural units (a1-10) to (a3-10) as long as the effects of the present invention are not impaired.
The structural unit (a4-10) is not particularly limited as long as it is another structural unit not classified into the structural units (a1-10) to (a3-10) described above, and for ArF excimer laser and KrF excimer laser. A number of hitherto known materials can be used for resist resins such as (preferably for ArF excimer laser).
As the structural unit (a4-10), 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 similar to those exemplified in the case of the structural unit (a3-10). For ArF excimer laser, for KrF excimer laser (preferably ArF excimer laser) A large number of hitherto known materials can be used for the resin component of the resist composition.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, an isobornyl group, and a norbornyl group is preferable in terms of industrial availability. These polycyclic groups may have a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.
Specific examples of the structural unit (a4-10) include structures having the following general formulas (a4-1) to (a4-5).

［式中、Ｒは前記と同じである。］

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

  When the structural unit (a4-10) is contained in the polymer (A2), the structural unit (a4-10) is added in an amount of 1 to 30 mol with respect to the total of all the structural units constituting the polymer (A2). % Is preferable, and 10 to 20 mol% is more preferable.

The polymer (A2) according to the present invention is a polymer having at least the structural unit (a1-10), and preferably a copolymer having the structural unit (a2-10) and / or (a3-10). It is.
Examples of such a copolymer include a copolymer composed of the structural units (a1-10) and (a2-10) (however, the structural unit (a4-10) may be included), and the structural unit (a1-10). And a copolymer consisting of (a3-10) (which may include the structural unit (a4-10)), a copolymer consisting of the structural units (a1-10), (a2-10) and (a3-10) A combination (however, the structural unit (a4-10) may be included) can be exemplified.

  A preferred specific example of the polymer (A2) is a polymer (A21) represented by the following general formula (A2-11). This polymer (A21) is excellent in lithography properties such as a resist pattern shape.

［式中、Ｒ、Ｒ^ａ〜Ｒ^ｃは前記と同じである。］

[Wherein, R and R ^{a to} R ^c are the same as defined above. ]

In formula (A2-11), R is most preferably a methyl group.
Most preferably, R ^{a to} R ^c are all ethyl groups.

The polymer (A2) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). .
Further, the polymer (A2) is used in combination with a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH in the above polymerization, -C terminated _{(CF 3)} may be introduced 2 -OH group. As described above, a polymer in which a hydroxyalkyl group in which a part of hydrogen atoms of an alkyl group is substituted with a fluorine atom is introduced has a reduction in development defects and LER (line edge roughness: uneven unevenness of line side walls). Effective for reduction.

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

In the component (A), the polymer (A2) may be used alone or in combination of two or more.
The content of the polymer (A2) in the component (A) is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and further preferably 10 to 30% by mass. When it is at least the lower limit value, the lithography characteristics such as the resist pattern shape are improved. By being below the upper limit value, it is possible to balance with other polymers.

・ Structural unit (a1-10 ′)
The polymer (A2) preferably does not have a structural unit (a1-10 ′) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group. By not having the structural unit (a1-10 ′), the effect of having the structural unit (a1-10) in the polymer (A2) is further improved.
Specific examples of the structural unit (a1-10 ′) include the same units as those described in the description of the structural unit (a1) of the polymer (A3) described later.

[Non-main chain cyclic polymer (A3)]
In the present invention, the non-main chain cyclic polymer (A3) has a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group.
The polymer (A3) preferably further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group.
The polymer (A3) preferably further has a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group.

  In the present invention, the polymer (A3) may contain the structural unit (a) in a proportion of 50 mol% or more with respect to the total of all the structural units constituting each non-main chain cyclic polymer. Preferably, it contains 70 mol% or more. Especially, since it is especially excellent in the effect of this invention, it is most preferable that this polymer (A3) consists only of the structural unit (a) induced | guided | derived from acrylic acid.

・ Structural unit (a1)
In the present invention, the structural unit (a1) is a structural unit derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group.
The acid dissociable, dissolution inhibiting group having a cyclic group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire polymer (A3) insoluble to alkali before dissociation, and this polymer (A3) after dissociation. As long as it changes the whole to alkali-soluble, the base resins for chemically amplified resists that have been proposed as acid dissociable, dissolution inhibiting groups having a cyclic group can be used. In general, a group that forms a cyclic tertiary alkyl ester with a carboxy group in (meth) acrylic acid, etc .; an acetal type acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group having a cyclic group is widely known. ing. The “(meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.

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

Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean a group, a compound, or the like that does not have aromaticity.
The “aliphatic cyclic group” means a monocyclic group or a polycyclic group having no aromaticity.
The “aliphatic cyclic group” in the structural unit (a1) may or may not have a substituent. Examples of the substituent include a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, and an oxygen atom (= O).
The basic ring structure excluding the substituent of the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group.
The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. The “aliphatic cyclic group” is preferably a polycyclic group.
Specific examples of the aliphatic cyclic group include, for example, a monocycloalkane, bicycloalkane, tricycloalkane, 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 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.
Examples of the acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group include a group having a tertiary carbon atom on the ring skeleton of a cyclic alkyl group. Specifically, 2-methyl-2 -Adamantyl group, 2-ethyl-2-adamantyl group, etc. are mentioned. Alternatively, in a structural unit represented by the following general formula, it binds to an aliphatic cyclic group such as an adamantyl group, like a group bonded to an oxygen atom of a carbonyloxy group (—C (O) —O—). And a group having a branched alkylene group having a tertiary carbon atom.

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

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

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

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

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

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

［式中、Ｒ^１’、ｎ、Ｙは上記と同様である。］

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

  The aliphatic cyclic group for Y can be appropriately selected from monocyclic or polycyclic aliphatic cyclic groups that have been proposed in a number of conventional ArF resists. For example, the above “aliphatic ring” Examples thereof are the same as those in the formula group.

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

［式中、Ｒ^１７、Ｒ^１８はそれぞれ独立して直鎖状または分岐鎖状のアルキル基または水素原子であり、Ｒ^１９は環状のアルキル基である。］

[Wherein, R ¹⁷ and R ¹⁸ each independently represent a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ represents a cyclic alkyl group. ]

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 cyclic alkyl group, preferably having 1 to 15 carbon atoms, more preferably 4 to 15 carbon atoms, still more preferably 4 to 12 carbon atoms, and 5 to 5 carbon atoms. 10 is most preferred. 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.

  As the structural unit (a1), one or more selected from the group consisting of structural units represented by the following general formula (a1-101) and structural units represented by the following general formula (a1-102) may be used. 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；Ｘ^１は環式基を有する酸解離性溶解抑制基を示す。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; and X ¹ represents an acid dissociable, dissolution inhibiting group having a cyclic 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は環式基を有する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 having a cyclic group; Y ² represents an alkylene group or an aliphatic ring A formula group is shown. ]

In the general formula (a1-101), the halogen atom, lower alkyl group or halogenated lower alkyl group of R is a halogen atom, lower alkyl group or halogenated lower alkyl group which may be bonded to the α-position of the acrylate ester. It is the same.
X ¹ is not particularly limited as long as it is an acid dissociable, dissolution inhibiting group having a cyclic group. For example, the above-described cyclic tertiary alkyl ester type acid dissociable, dissolution inhibiting group, acetal type having a cyclic group are used. Examples include acid dissociable, dissolution inhibiting groups, and cyclic tertiary alkyl ester type acid dissociable, dissolution inhibiting groups are preferred.

In general formula (a1-102), R is the same as defined above.
X ² is the same as X ¹ in formula (a1-101).
Y ² is preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group, and the aliphatic cyclic group is the above except that a group in which two or more hydrogen atoms are removed is used. The thing similar to description of an "aliphatic cyclic group" can be used.

  More specifically, examples of the structural unit (a1) include structural units represented by the following general formulas (a1-1) to (a1-4).

［式中、Ｘ’は環状の第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。］

[Wherein, X ′ represents a cyclic tertiary alkyl ester-type acid dissociable, dissolution inhibiting group, Y represents an aliphatic cyclic group; n represents an integer of 0 to 3; R represents the same as defined above, and 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 cyclic 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.

Among the above, the structural unit represented by the 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^１３は低級アルキル基を示す。］

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹³ represents a lower alkyl group. ]

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

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and R ¹² represents a lower alkyl group. h represents an integer of 1 to 3. ]

In general formula (a1-1-01), R is the same as defined above. The lower alkyl group for R ^{13 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably a methyl group.

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

In the polymer (A3), as the structural unit (a1), one type of structural unit may be used, or two or more types may be used in combination.
The proportion of the structural unit (a1) in the polymer (A3) is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, based on the total of all structural units constituting the polymer (A3). 25-50 mol% 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 polymer (A3) according to the present invention preferably has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group, in addition to the structural unit (a1). By having the structural unit (a2), when the polymer (A3) is used for forming a resist film, the adhesion of the resist film to the substrate and the affinity with a developer containing water are improved.
Specific examples of the structural unit (a2) are the same as those described in the description of the structural unit (a2-10) of the polymer (A2), and a description thereof will be omitted.
In the polymer (A3), as the structural unit (a2), one type of structural unit may be used alone, or two or more types may be used in combination.
The proportion of the structural unit (a2) in the polymer (A3) is preferably from 5 to 60 mol%, more preferably from 10 to 50 mol%, based on the total of all the structural units constituting the polymer (A3). 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 (a3)
The polymer (A3) according to the present invention is an acrylic 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). It is preferable to have a derived structural unit (a3). By having the structural unit (a3), the hydrophilicity of the polymer (A3) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. .
Specific examples of the structural unit (a3) are the same as those described in the description of the structural unit (a3-10) of the polymer (A2), and thus the description thereof is omitted.
In the polymer (A3), as the structural unit (a3), 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 (a3) in the polymer (A3) is preferably 5 to 50 mol%, preferably 5 to 40 mol%, based on the total of all the structural units constituting the polymer (A3). More preferably, it is more preferably 5 to 25 mol%. By setting it to the lower limit value or more, the effect of containing the structural unit (a3) can be sufficiently obtained, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

・ Other structural units (a4)
The polymer (A3) according to the present invention may contain other structural units (a4) other than the structural units (a1) to (a3) as long as the effects of the present invention are not impaired.
Specific examples of the structural unit (a4) are the same as those described in the description of the structural unit (a4-10) of the polymer (A2), and a description thereof will be omitted.
When the structural unit (a4) is contained in the polymer (A3), the structural unit (a4) is contained in an amount of 1 to 30 mol%, preferably 1% to the total of all the structural units constituting the polymer (A3). It is preferable to contain 10 to 20 mol%.

The polymer (A3) according to the present invention is a polymer having at least the structural unit (a1), and is preferably a copolymer further having the structural unit (a2) and / or (a3).
As such a copolymer, for example, a copolymer composed of the structural units (a1) and (a2) (however, the structural unit (a4) may be included), a copolymer composed of the structural units (a1) and (a3) Examples thereof include a combination (provided that the structural unit (a4) may be included), a copolymer composed of the structural units (a1), (a2), and (a3) (however, the structural unit (a4) may be included). .

  A preferred specific example of the polymer (A3) is a polymer (A31) represented by the following general formula (A3-11). This polymer (A31) is excellent in resolution.

［式中、Ｒは前記と同じであり、Ｒ^１０は低級アルキル基である。］

[Wherein, R is the same as defined above, and R ¹⁰ represents a lower alkyl group. ]

In formula (A3-11), the lower alkyl group for R ^{10 is the same as} the lower alkyl group for R, preferably a methyl group or an ethyl group, and most preferably a methyl group.

  The manufacturing method of a polymer (A3) can be obtained by making it superpose | polymerize by the manufacturing method similar to the said polymer (A2) using the monomer which derives each structural unit.

The mass average molecular weight (Mw) (polystyrene conversion standard by gel permeation chromatography) of the polymer (A3) is not particularly limited, but is preferably 2000 to 50000, more preferably 3000 to 30000, and 5000 to 20000. Most preferred. When it is smaller than the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist. When it is larger than the lower limit of this range, dry etching resistance and resist pattern cross-sectional shape are good.
Further, the dispersity (Mw / Mn) of the polymer (A3) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

In the component (A), the polymer (A3) may be used alone or in combination of two or more.
40-90 mass% is preferable, as for content of the polymer (A3) in (A) component, 50-85 mass% is more preferable, and 55-80 mass% is further more preferable. When it is at least the lower limit value, the lithography characteristics such as the resist pattern shape are improved. By being below the upper limit value, it is possible to balance with other polymers.

In the component (A), the mixing ratio of the main chain cyclic polymer (polymer (A1)) and the non-main chain cyclic polymer (polymer (A2) and polymer (A3)) is the ratio of the present invention. Since the effect is excellent, it is preferable that the main chain cyclic polymer: non-main chain cyclic polymer = 1: 99 to 99: 1 by mass ratio.
: 95 to 75:25 is more preferable, 10:90 to 75:25 is particularly preferable, and 10:90 to 50:50 is most preferable.
Further, in the non-main chain cyclic polymer, the mixing ratio of the polymer (A2) and the polymer (A3) improves the lithography characteristics, so that the polymer (A2): polymer (A3) is in mass ratio. = 5: 95-50: 50 is preferable, 10: 90-40: 60 is more preferable, and 10: 90-30: 70 is most preferable.
In the positive resist composition for immersion exposure according to the present invention, the total content of the component (A) may be adjusted according to the resist film thickness to be formed.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

［式（Ｂ−１）中、Ｒ^３１、Ｒ^３２はそれぞれ独立に有機基を表す。］

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

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

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

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

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

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

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

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

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

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

The alkyl group or halogenated alkyl group having no substituent 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 increases. 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).
The content of the component (B) in the positive resist composition for immersion exposure according to the present invention is 0.5 to 30 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the component (A). . By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

<(D) component>
In the positive resist composition for immersion exposure according to the present invention, a nitrogen-containing organic compound (D) (hereinafter referred to as (D)) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Component)).
Since a wide variety of components (D) have already been proposed, any known one may be used. Cyclic amines, aliphatic amines, particularly secondary aliphatic amines and tertiary fats may be used. Group amines are preferred. Here, the aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include 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.

<Optional component>
The positive resist composition for immersion exposure of the present invention includes an organic carboxylic acid and a phosphorus oxo as an optional component for the purpose of preventing sensitivity deterioration and improving the resist pattern shape and stability with time. At least one compound (E) selected from the group consisting of acids and derivatives thereof (hereinafter referred to as component (E)) can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of the phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
As the component (E), an organic carboxylic acid is preferable, and salicylic acid is particularly preferable.
(E) A component may be used individually by 1 type and may use 2 or more types together.
When the component (E) is contained in the positive resist composition for immersion exposure, it is usually used at a ratio of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

  The positive resist composition for immersion exposure according to the present invention may further contain a miscible additive as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, a dye, and the like can be appropriately added and contained.

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

According to the positive resist composition for immersion exposure of the present invention, substance elution during immersion exposure can be suppressed, and the lithography characteristics are also good.
Although the reason which can suppress the substance elution at the time of immersion exposure is not clear, by using the polymer (A1), (A2) and (A3) as the component (A), for example, the polymer (A1) is used. First, it is considered that one of the main factors is that the receding angle of the resulting resist film is increased and the falling angle is decreased as compared with the combination of the polymers (A2) and (A3) alone.
That is, the resist film formed using the positive resist composition for immersion exposure according to the present invention has a component (A) as compared with a case where, for example, a combination of polymers (A2) and (A3) alone is used. , Dynamic contact angle to water (Contact angle when water droplets start to fall when the resist film is tilted. Contact angle (advance angle) at the front end point of the water drop direction and end point behind the drop direction) And a fall angle (the tilt angle of the resist film when a water droplet starts to fall when the resist film is tilted). For example, the receding angle increases, while the falling angle decreases.
In immersion exposure, as described above, the resist film comes into contact with an immersion solvent such as water during immersion exposure. Therefore, it is presumed that substance elution is influenced by the characteristics (for example, hydrophilicity / hydrophobicity) of the resist film surface. In the present invention, by using the component (A) containing three specific types of polymers, these characteristics are changed, and thereby a resist film that hardly causes substance elution and that has good lithography characteristics can be obtained. Presumed to be 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 an angle θ ₁ formed by the upper end 1 a of the droplet 1 with respect to the plane 2. The falling angle is an inclination angle θ ₂ of the plane 2 when the droplet 1 starts to move (drop) on the plane 2.

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

In the positive resist composition for immersion exposure according to the present invention, the measured value of the receding angle in a resist film obtained using the resist composition is preferably 45 degrees or more, more preferably 50 to 150 degrees. It is preferably 55 to 130 degrees, and most preferably 60 to 100 degrees. When the receding angle is 45 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. Further, when the receding angle is 150 degrees or less, the lithography characteristics and the like are good.
In the positive resist composition for immersion exposure according to the present invention, the measured value of the falling angle in a resist film obtained using the resist composition is preferably 36 ° or less, and preferably 10 to 36 °. Is more preferable, 12 to 30 degrees is particularly preferable, and 15 to 25 degrees is most preferable. When the sliding angle is 36 ° or less, the substance elution suppression effect during immersion exposure is improved. In addition, when the falling angle is 10 degrees or more, the lithography characteristics and the like are good.

  The size of the receding angle and the falling angle depends on the composition of the positive resist composition for immersion exposure, for example, the mixing ratio of the polymers (A1), (A2) and (A3) in the component (A), and the structural unit. It can be controlled by adjusting the ratio of (a3-10) and (a3). For example, by increasing the proportion of the polymer (A1) in the component (A), the receding angle becomes significantly larger and the falling angle is smaller than when the polymer (A2) and (A3) are used alone. Become.

  As described above, in the present invention, substance elution into the immersion solvent is suppressed. For this reason, it is considered that alteration of the resist film and change in the refractive index of the immersion solvent are also suppressed. As a result, it is conceivable that pattern waviness and LER (line edge roughness: uneven unevenness of the line side wall) are reduced, and lithography characteristics such as a resist pattern shape are improved. Further, it is considered that the contamination of the lens of the exposure apparatus is reduced by the present invention. Thus, it is considered that it is not necessary to take protective measures against these, and it can contribute to simplification of the process and the exposure apparatus.

Moreover, the positive resist composition for immersion exposure according to the present invention has good lithography properties. The reason is not clear, but is presumed as follows.
In the present invention, a polymer (A3) effective for forming a fine resist pattern is used, and further a structural unit (a1−) containing an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group. A polymer (A2) having 10) is used. In particular, it is considered that the acid dissociable, dissolution inhibiting group in the polymer (A2) is chain-like, so that it is not bulky compared to a cyclic group and has a low acid dissociation energy. Therefore, it is presumed that the acid dissociable, dissolution inhibiting group is easily dissociated by exposure, and the exposed portion of the resist film can be rapidly dissolved in the developer.
As described above, in the present invention, by using the polymer (A2) together with the polymer (A3), a resist pattern having high rectangularity and reduced roughness such as side walls can be obtained, and lithography such as shape can be performed. The characteristics are also considered to be good.

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

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

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

As described above, in the resist pattern forming method of the present invention, the space between the resist film and the lowermost lens of the exposure apparatus is filled with the immersion medium during exposure, and exposure (immersion exposure) is performed in that state.
At this time, the immersion medium is preferably a solvent having a refractive index greater than that of air and having a refractive index of a resist film formed using a positive resist composition for immersion exposure. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, 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.).

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

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

<Resin component (A)>
The polymers (A1) to (A3) of the component (A) used in Examples and Comparative Examples are shown below.
In addition, the mass mean molecular weight (Mw) and dispersity (Mw / Mn) of each polymer were written together.
The mass average molecular weight (Mw) and dispersity (Mw / Mn) were determined on a polystyrene conversion basis by gel permeation chromatography (GPC).
The composition ratio was calculated by carbon NMR. In the chemical formula, the number attached to the lower right of the structural unit indicates the ratio (mol%) of each structural unit in the polymer.

（Ｍｗ：５７００、Ｍｗ／Ｍｎ：１．６；プロメラス社製のものを用いた。）

(Mw: 5700, Mw / Mn: 1.6; those manufactured by Promeras were used.)

（Ｍｗ：１００００、Ｍｗ／Ｍｎ：１．８；各構成単位を誘導するモノマーを用いて公知の滴下重合法により合成した。）

(Mw: 10,000, Mw / Mn: 1.8; synthesized by a known dropping polymerization method using monomers for deriving each structural unit.)

（Ｍｗ：１００００、Ｍｗ／Ｍｎ：１．７；各構成単位を誘導するモノマーを用いて公知の滴下重合法により合成した。）

(Mw: 10,000, Mw / Mn: 1.7; synthesized by a known dropping polymerization method using monomers for deriving each structural unit.)

<Preparation of positive resist composition solution for immersion exposure>
(Examples 1-2, Comparative Example 1)
The components shown in Table 1 were mixed and dissolved to prepare a positive resist composition solution for immersion exposure.

Each abbreviation in Table 1 has the following meaning. Moreover, the numerical value in [] is a compounding quantity (mass part).
(B) -1: Triphenylsulfonium nonafluorobutanesulfonate.
(B) -2: (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate.
(D) -1: Triethanolamine.
(S) -1: PGMEA / PGME = 6/4 (mass ratio) mixed solvent.

<Evaluation of inhibitory effect on substance elution>
The following evaluation was performed using the obtained positive resist composition solution for immersion exposure.

[Measurement of receding angle and falling angle]
The obtained positive resist composition solution for immersion exposure is applied onto a silicon wafer having a diameter of 8 inches using a spinner, pre-baked on a hot plate at 115 ° C. for 60 seconds, and dried. A 150 nm resist film was formed. One drop (50 μl) of pure water was dropped on the resist film, and then the receding angle and the falling angle were measured with the following apparatus and conditions (the receding angle and the falling angle before exposure), respectively.
(equipment 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 (included with the device))
FAMAS.

In addition, 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 (trade name, manufactured by RISOTEC Japan Co., Ltd.). ), The receding angle and the falling angle were measured in the same manner as described above (the receding angle and the falling angle after exposure).
Table 2 shows the measurement results of the receding angle and the falling angle of the resist film before and after the exposure.

  From the results of Table 2, Examples 1 and 2 containing the polymers (A1), (A2) and (A3) according to the present invention are before exposure compared to Comparative Example 1 containing no polymer (A1).・ It was confirmed that the falling angle decreased and the receding angle increased after exposure.

[Measurement of eluate]
Using the positive resist composition solutions for immersion exposure of Examples 1-2 and Comparative Example 1, resist films were formed in the same manner as described above.
Next, using VRC310S (trade name, manufactured by SS Co., Ltd.), 1 drop (50 μl) of pure water is moved at room temperature at a constant linear velocity so as to draw a circle from the center of the wafer at room temperature. (The total contact area of the resist film in contact with the droplet was 221.56 cm ² ).
Thereafter, the droplets are collected and analyzed by an analyzer Agilent-HP1100 LC-MSD (trade name, manufactured by Agilent Technologies), and the cation part (PAG +) and anion part (PAG) of the component (B) before exposure. The total elution amount (mol / cm ² ) of the components (−) and (D) was determined. These results are shown in Table 3.

In addition, a resist film is formed in the same manner as described above, and 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 Co., Ltd.). went.
Next, the exposed resist film was analyzed in the same manner as described above, and the total elution amount (mol / mol) of the cation part (PAG +), the anion part (PAG−), and the component (D) of the (B) component after exposure was analyzed. cm ² ). These results are shown in Table 3.
In Table 3, “−” was described for those whose elution amount was less than the detection limit.

From the result of Table 3, Examples 1-2 which concern on this invention are the sum total of (B) component and (D) component in the immersion medium (water) before and behind exposure processing compared with the comparative example 1. The amount of elution was reduced, and it was confirmed that the substance elution suppression effect during immersion exposure was high.
In particular, the elution amount of PAG- before and after exposure in Examples 1 and 2 was smaller than that in Comparative Example 1, and in particular, the elution amount of PAG- after exposure was particularly small.

  In addition, from the measurement results of the receding angle and the falling angle (Table 2) and the measurement result of the eluted substance (Table 3), there is a correlation between the receding angle increasing and the falling angle decreasing, and the substance elution suppression effect I understand that there is.

<Evaluation of lithography properties>
Lithographic properties were evaluated using the positive resist composition solutions for immersion exposure obtained in Examples 1 and 2 and Comparative Example 1.
An organic antireflection film composition “ARC29” (trade name, manufactured by Brewer Science Co., Ltd.) is applied onto an 8-inch silicon wafer using a spinner, and is baked and dried on a hot plate at 205 ° C. for 60 seconds. Thus, an organic antireflection film having a thickness of 77 nm was formed. Then, the positive resist composition solution for immersion exposure obtained above is applied onto an antireflection film using a spinner, and prebaked (PAB) on a hot plate at 115 ° C. for 60 seconds. By performing the treatment and drying, a resist film having a thickness of 150 nm was formed.
Next, an ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S302 (manufactured by Nikon; NA (numerical aperture) = 0.60, 2/3 annular illumination). . Then, a post-exposure heating (PEB) treatment was performed at 115 ° C. for 60 seconds, and further developed at 23 ° C. with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds. Thereafter, the substrate was rinsed with pure water for 30 seconds and then shaken and dried to form a line-and-space (1: 1) resist pattern (hereinafter referred to as L / S pattern).

[Evaluation of resist pattern shape]
The shape of the L / S pattern having a line width of 120 nm and a pitch of 240 nm was observed with a scanning electron microscope (SEM).

As a result of the evaluation of the resist pattern shape, it was confirmed that the resist pattern shapes of Examples 1 and 2 according to the present invention have high rectangularity.
On the other hand, in the resist pattern shape of Comparative Example 1, the TOP of the pattern was slightly rounded.

  From the above results, it was confirmed that Examples 1 and 2 according to the present invention can suppress substance elution during immersion exposure and have excellent lithography characteristics.

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

Claims (15)

A positive resist for immersion exposure comprising a resin component (A) having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid, and an acid generator component (B) that generates an acid upon exposure. A composition comprising:
The resin component (A) is a structural unit (a1-10) derived from an acrylic ester containing a main chain cyclic polymer (A1) and an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group. And a non-main chain cyclic polymer (A2) having a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group ( A positive resist composition for immersion exposure, comprising A3). The structural unit (a1-10) has the following general formula (a1-0-1)

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ¹¹ represents an acid dissociable, dissolution inhibiting group composed of a chain-like tertiary alkyl group having 4 or more carbon atoms. . ]
The positive resist composition for immersion exposure according to claim 1, comprising a structural unit (a1-11) represented by: The structural unit (a1-11) has the following general formula (a1-0-2)

[Wherein, R represents a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; R ^{a to} R ^c each independently represents a lower alkyl group having 1 to 5 carbon atoms. ]
The positive resist composition for immersion exposure according to claim 2, comprising a structural unit represented by formula (a1-1-11).   The non-main chain cyclic polymer (A2) does not have a structural unit (a1-10 ') derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group having a cyclic group. The positive resist composition for immersion exposure according to any one of the above.   The non-main-chain cyclic polymer (A2) further has a structural unit (a2-10) derived from an acrylate ester containing a lactone-containing cyclic group. A positive resist composition for immersion exposure.   The non-main-chain cyclic polymer (A2) further has a structural unit (a3-10) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. A positive resist composition for immersion exposure as described in 1. above.   The positive resist for immersion exposure according to any one of claims 1 to 6, wherein the main chain cyclic polymer (A1) is a polymer having a structural unit derived from polycycloolefin in the main chain. Composition. The main chain cyclic polymer (A1) has the following general formula (a′1):

[Wherein, R ⁶¹ represents a lower alkyl group, a ″ is 0 or 1, and b ″ is an integer of 1 to 3. ]
The positive resist composition for immersion exposure according to claim 7, comprising a structural unit (a′1) represented by: The main chain cyclic polymer (A1) is further represented by the following general formula (a′2):

[Wherein R ⁶² and R ⁶³ each independently represent a hydrogen atom or a lower alkyl group, and a ″ is 0 or 1.]
The positive resist composition for immersion exposure according to claim 8, having a structural unit (a′2) represented by: The main chain cyclic polymer (A1) is further represented by the following general formula (a′3):

[Wherein R ⁶⁴ is an organic group having an alkali-soluble group, and a ″ is 0 or 1.]
The positive resist composition for immersion exposure according to claim 8 or 9, which has a structural unit (a'3) represented by: R ⁶⁴ in the general formula (a′3) represents the following general formula (a′31)

[Wherein c ″ is an integer of 1 to 5, and d ″ and e ″ are each independently an integer of 1 to 5.]
The positive resist composition for immersion exposure according to claim 10, which is a group represented by the formula:   The liquid immersion according to any one of claims 1 to 11, wherein the non-main-chain cyclic polymer (A3) further has a structural unit (a2) derived from an acrylate ester containing a lactone-containing cyclic group. A positive resist composition for exposure.   The non-main-chain cyclic polymer (A3) further has a structural unit (a3) derived from an acrylate ester containing a polar group-containing aliphatic hydrocarbon group. A positive resist composition for immersion exposure.   Furthermore, the positive resist composition for immersion exposure as described in any one of Claims 1-13 containing a nitrogen-containing organic compound (D). A step of forming a resist film on a substrate using the positive resist composition for immersion exposure according to any one of claims 1 to 14, a step of immersion exposure of the resist film, and developing the resist film A resist pattern forming method including a step of forming a resist pattern.

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