JP5834985B2 - Resist composition for immersion exposure - Google Patents

Description

  The present invention relates to a resist composition for immersion exposure.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, conventionally, a resist film is formed on a substrate with a resin composition containing a polymer having an acid-dissociable group, and excimer laser light or the like is passed through a mask pattern. A fine resist pattern is formed by exposing a resist film by irradiation with short-wave radiation and removing an exposed portion with an alkaline developer. At this time, a “chemically amplified resist” in which an acid generator that generates an acid upon irradiation with radiation is contained in the resin composition and the sensitivity is improved by the action of the acid is used.

  In such a chemically amplified resist, the use of the immersion exposure method is expanding as a method for forming a finer resist pattern. In this method, exposure is performed by filling the space between the exposure lens and the resist film with an immersion exposure liquid having a higher refractive index than air or an inert gas. According to this immersion exposure method, there is an advantage that even when the numerical aperture of the lens is increased, the depth of focus is hardly lowered and high resolution is obtained.

  As the resin composition used in the immersion exposure method, fluorine having high water repellency is used for the purpose of preventing elution of an acid generator and the like from the resist film to the immersion exposure solution and improving the drainage of the resist film. A resist composition for immersion exposure containing a containing polymer has been proposed (see International Publication No. 2007/116664), and for the purpose of suppressing development defects in unexposed areas accompanying water repellency of the resist film. A carboxylic acid-generating fluorine-containing polymer that is water-repellent during immersion exposure and hydrophilic during alkali development has been proposed (see Japanese Patent Application Laid-Open No. 2010-032994). According to this carboxylic acid-generating fluorine-containing polymer, the alkali-dissociable group of the polymer is dissociated during development with an alkaline developer to generate a carboxylic acid, and the hydrophilicity is increased by the carboxylic acid to increase the alkali development. As a result of being easily soluble in the liquid, development defects are reduced.

  However, even when the fluorine-containing polymer is used, the development defects are still insufficiently reduced. In addition, the composition containing the carboxylic acid-generating fluorine-containing polymer generates a carboxylic acid by dissociation of an alkali-dissociable group, although in a small amount even during alkali development, and the carboxylic acid and the composition There is an inconvenience that a poorly soluble salt is formed with other coexisting components and precipitates to cause a decrease in storage stability as a photoresist composition.

International Publication No. 2007/116664 JP 2010-032994 A

  The present invention has been made based on the above circumstances, and its object is to sufficiently satisfy general characteristics such as sensitivity and LWR (Line width roughness) and to reduce development defects during development. It is an object of the present invention to provide a resist composition for immersion exposure that can be used and has excellent storage stability.

（式（ｉ）中、Ｒ^１は、アルカリ解離性基である。Ａは、−ＳＯ_２−Ｏ−＊、−ＳＯ−Ｏ−＊、−ＮＯ−Ｏ−＊、−Ｎ−Ｏ−＊、−Ｂ（ＯＲ^ａ１）−Ｏ−＊、−Ｐ（＝Ｏ）（ＯＲ^ａ２）−Ｏ−＊又は下記式（ｉｉ）で表される基である。＊は、上記Ｒ^１との結合部位を示す。Ｒ^ａ１及びＲ^ａ２は、それぞれ独立して、炭素数１〜２０の１価の炭化水素基である。）

（式（ｉｉ）中、ｍは、０〜１０の整数である。＊は、上記Ｒ^１との結合部位を示す。） The invention made to solve the above problems is
[A] a polymer having a structural unit (I) containing a group represented by the following formula (i) and containing a fluorine atom (hereinafter also referred to as “[A] polymer”), and [B] acid A resist composition for immersion exposure containing a generator.

(In formula (i), R ¹ is an alkali-dissociable group. A is —SO ₂ —O— *, —SO—O— *, —NO—O— *, —N—O— *, —B (OR ^a1 ) —O— *, —P (═O) (OR ^a2 ) —O— *, or a group represented by the following formula (ii), where * represents a binding site with R ¹ . R ^a1 and R ^a2 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.)

(In the formula (ii), m is an integer of 0 to 10. * indicates the binding site with R ^1. )

  The resist composition for immersion exposure according to the present invention contains the [A] polymer containing fluorine atoms, thereby improving the water repellency of the resist film to be formed and elution of acid generators and the like from the resist film. Can be suppressed. In particular, when used together with other polymers, this [A] polymer is unevenly distributed on the resist film surface, so that the above effect can be further enhanced. In addition, since the polymer [A] contains the specific group represented by the above formula (i), it becomes easily soluble in an alkali developer due to dissociation of the alkali dissociable group during development, thereby reducing development defects. And the storage stability of the composition can be enhanced. In particular, even when used together with an acid diffusion controller, the [A] polymer contains a specific group represented by the above formula (i), so that the storage stability is excellent.

（式（１）中、Ｒ^１及びＡは、上記式（ｉ）と同義である。Ｘは、単結合又は炭素数１〜２０の２価の鎖状炭化水素基である。但し、上記鎖状炭化水素基が有する水素原子の一部又は全部は、フッ素原子で置換されていてもよい。Ｒ^２は、単結合、炭素数１〜２０の２価の鎖状炭化水素基又は炭素数３〜２０の２価の脂環式炭化水素基である。Ｒ^３は、炭素数１〜２０の（ｎ＋１）価の炭化水素基、又は炭素数１〜２０の（ｎ＋１）価の炭化水素基と−ＣＯ−、−ＣＯＯ−、−ＯＣＯ−、−Ｏ−、−ＮＲ−、−ＣＳ−、−Ｓ−、−ＳＯ−、及び−ＳＯ_２−からなる群より選択される少なくとも１種の基とを組み合わせた基である。但し、ｎが１の場合、Ｒ^３は、単結合であってもよい。また、上記（ｎ＋１）価の炭化水素基が有する水素原子の一部又は全部は、フッ素原子で置換されていてもよい。Ｅは、単結合、酸素原子、−ＣＯ−Ｏ−＊又は−ＣＯ−ＮＨ−＊である。＊は、上記Ｒ^３との結合部位を示す。Ｒ^４は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。ｎは、１〜３の整数である。ｎが２以上の場合、複数のＲ^１、Ａ、Ｘ及びＲ^２は、それぞれ同一でも異なっていてもよい。） The structural unit (I) is preferably represented by the following formula (1).

(In Formula (1), R < ¹ > and A are synonymous with the said Formula (i). X is a single bond or a C1-C20 bivalent chain hydrocarbon group, provided that the above chain A part or all of hydrogen atoms of the hydrocarbon group may be substituted with a fluorine atom, R ² is a single bond, a divalent chain hydrocarbon group having 1 to 20 carbon atoms or 3 carbon atoms. A divalent alicyclic hydrocarbon group having ˜20, R ³ is an (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms, or an (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms; At least one group selected from the group consisting of —CO—, —COO—, —OCO—, —O—, —NR—, —CS—, —S—, —SO—, and —SO ₂ —; is a group combining. However, when n is 1, R ³ may be a single bond. in addition, the (n + 1) hydrogen with the valent hydrocarbon group Some or all of the child, may be substituted with a fluorine atom .E represents a single bond, an oxygen atom, a -CO-O-* or -CO-NH- *. * Is the above ^{R 3} R ⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, n is an integer of 1 to 3. When n is 2 or more, a plurality of R ¹ , A , X and R ² may be the same or different.

  Thus, since the [A] polymer has the specific structural unit (I), development defects can be reduced and a resin component excellent in storage stability can be provided.

  The resist composition for immersion exposure further contains [C] a polymer having a smaller fluorine atom content than the above [A] polymer (hereinafter also referred to as “[C] polymer”). It is preferable that the polymer has an acid dissociable group.

  Thus, when the resist composition for immersion exposure further contains the [C] polymer, when the resist film is formed from the composition containing the [A] polymer and the [C] polymer, [A] Since the degree of uneven distribution of the polymer on the resist film surface is increased, the water repellency of the [A] polymer is efficiently expressed.

A in the formula (i) is preferably —SO ₂ —O— * or —NO—O— *. Thus, when A is a specific group, the high acidity of the acid generated by the dissociation of the alkali-dissociable group makes the [A] polymer more soluble in an alkaline developer and further reduces development defects. can do.

（式（ｉｉｉ）中、Ｒ^５及びＲ^６は、それぞれ独立して、炭素数１〜２０の１価の有機基である。但し、上記Ｒ^５とＲ^６とが互いに結合して、それらが結合している炭素原子と共に環構造を形成してもよい。）

（式（ｉｖ）中、Ｒ^７及びＲ^８は、それぞれ独立して、炭素数１〜２０の１価の有機基である。但し、上記Ｒ^７とＲ^８とが互いに結合して、それらが結合している窒素原子と共に環構造を形成してもよい。）

（式（ｖ）中、Ｒ^９は、炭素数１〜２０の１価の炭化水素基又は炭素数１〜２０の１価のフッ素化炭化水素基である。） R ¹ in the above formula (i) is preferably represented by any of the following formulas (iii) to (v).

(In formula (iii), R ⁵ and R ⁶ are each independently a monovalent organic group having 1 to 20 carbon atoms, provided that R ⁵ and R ⁶ are bonded to each other, and (A ring structure may be formed with the carbon atom to which it is bonded.)

(In formula (iv), R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms, provided that R ⁷ and R ⁸ are bonded to each other, and (A ring structure may be formed together with the nitrogen atom bonded thereto.)

(In formula (v), R ⁹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.)

Thus, when R ¹ is the specific group, the dissociation property of the alkali dissociable group with respect to the alkali developer can be improved, and the polymer [A] is easily soluble in the alkali developer. Development defects can be further reduced.

  It is preferable that the resist composition for immersion exposure further contains a [D] acid diffusion controller. Thus, when the resist composition for immersion exposure further contains the [D] acid diffusion controller, the resist pattern shape can be improved. Moreover, the storage stability of the said composition can be improved more by using in combination with the [A] polymer containing the specific group represented by the said Formula (i).

  [D] The acid diffusion controller is preferably a photodegradable acid diffusion controller. Thus, the resist pattern shape can be improved because the [D] acid diffusion controller is a photodegradable acid diffusion controller. Moreover, the storage stability of the said composition can be improved further by using it in combination with the [A] polymer containing the specific group represented by the said Formula (i).

  According to the resist composition for immersion exposure of the present invention, a resist film that can sufficiently satisfy general characteristics such as sensitivity and LWR can be formed, and development defects can be reduced by being easily dissolved in an alkaline developer during development. It is also excellent in storage stability. Therefore, the resist composition for immersion exposure can be suitably used for a manufacturing process using an immersion exposure method in a semiconductor device in which further miniaturization of a pattern proceeds.

<Resist composition for immersion exposure>
The resist composition for immersion exposure of the present invention contains [A] a polymer and [B] an acid generator. Moreover, the said composition may contain the [C] polymer and the [D] acid diffusion control body as a suitable component. Furthermore, the said composition may contain another arbitrary component in the range which does not impair the effect of this invention. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having a structural unit (I) containing a group represented by the above formula (i) and containing a fluorine atom. [A] Since the polymer contains fluorine atoms, the water repellency of the formed resist film is improved, elution of the acid generator and the like from the resist film can be suppressed, and excellent drainage characteristics are exhibited. In particular, when used together with other polymers such as the later-described [C] polymer that is usually used in combination, the surface distribution of the [A] polymer tends to increase and become unevenly distributed. The effect can be further enhanced. [A] The fluorine atom content of the polymer is preferably 5% by mass or more, more preferably 7% by mass or more, and further preferably 10% by mass or more. The fluorine atom content can be calculated from this structure by identifying the structure of the polymer using ¹³ C-NMR.

  In addition, the [A] polymer contains a specific group represented by the above formula (i), so that a hydroxyl group is generated by the dissociation of an alkali dissociable group during development and becomes easily soluble in an alkali developer. Since the wettability increases, the composition can reduce development defects. Moreover, the storage stability of the said composition can be improved because a [A] polymer contains the specific group represented by the said Formula (i).

  [A] The polymer may have structural units other than the structural unit (I) (for example, structural units (II) and (III) described later) within a range not impairing the effects of the present invention. In addition, the [A] polymer may have 2 or more types of each structural unit.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a group represented by the above formula (i).
In the above formula (i), R ¹ is an alkali dissociable group. A represents —SO ₂ —O— *, —SO—O— *, —NO—O— *, —N—O— *, —B (OR ^a1 ) —O— *, —P (═O) ( OR ^a2 ) —O— * or a group represented by the above formula (ii). * Indicates the binding site to R ¹ described above. R ^a1 and R ^a2 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.

  Here, the alkali-dissociable group is a group that substitutes a hydrogen atom in a polar functional group such as a hydroxy group or a sulfo group, and is in the presence of an alkali (for example, tetramethylammonium hydroxide 2 at 23 ° C. A group that dissociates in a 38 mass% aqueous solution).

The alkali dissociable group represented by R ¹ is not particularly limited as long as it dissociates in the presence of an alkali to generate a polar group, but is represented by any one of the above formulas (iii) to (v). It is preferably a group. When R ¹ is the specific group, the dissociation property of the alkali-dissociable group with respect to the alkali developer can be improved, and easily dissociates in the presence of an alkali during alkali development to form a hydroxyl group. A] The polymer can be easily dissolved in an alkali developer to further reduce development defects.

In the above formula (iii), R ⁵ and R ⁶ are each independently a monovalent organic group having 1 to 20 carbon atoms. However, R ⁵ and R ⁶ may be bonded to each other to form a ring structure together with the carbon atom to which they are bonded.

In the above formula (iv), R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms. However, R ⁷ and R ⁸ may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded.

In said formula (v), R < ⁹ > is a C1-C20 monovalent hydrocarbon group or a C1-C20 monovalent fluorinated hydrocarbon group.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^{5 to} R ⁸ include, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or —CO—, —COO—, and —OCO. At least one group selected from the group consisting of —, —O—, —NR—, —CS—, —S—, —SO—, and —SO ₂ —, and monovalent carbonization having 1 to 20 carbon atoms. Examples include a group in combination with a hydrogen group.

  Part or all of the hydrogen atoms of the monovalent hydrocarbon group may be substituted with a substituent. As said substituent, a fluorine atom, a hydroxy group, a carboxy group, a cyano group etc. are mentioned, for example.

R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. As the monovalent organic group represented by R, for example, the same groups as those exemplified for the above R ^{5 to} R ⁸ can be applied.

  Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms and a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

  Examples of the alkyl group having 1 to 20 carbon atoms include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group; i-propyl group, i-butyl group, sec- Examples thereof include branched alkyl groups such as a butyl group and a t-butyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, methylcyclohexyl group, and ethyl. Monocyclic saturated hydrocarbon group such as cyclohexyl group; cyclobutenyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, cyclooctenyl group, cyclodecenyl group, cyclopentadienyl group, cyclohexadienyl group, cyclooctadienyl group, cyclo Monocyclic unsaturated hydrocarbon group such as decadiene; bicyclo [2.2.1] heptyl group, bicyclo [2.2.2] octyl group, tricyclo [5.2.1.0 ^2,6 ] decyl group , Tricyclo [3.3.1.1 ^3,7 ] decyl group, tetracyclo [6.2. 1.1 ^{3, 6} . 0 ^2,7 ] dodecyl group, norbornyl group, polycyclic saturated hydrocarbon group such as adamantyl group and the like. The “alicyclic hydrocarbon group” does not need to be composed only of the structure of the alicyclic hydrocarbon, and a part thereof may include a chain structure.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ⁵ and R ⁶ include a monovalent hydrocarbon group having 1 to 20 carbon atoms and a monovalent fluorinated carbon having 1 to 20 carbon atoms. A hydrogen group is preferred.

The monovalent organic group having 1 to 20 carbon atoms represented by R ⁷ and R ⁸ is preferably a group in which —CO— and a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms are combined.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the R ⁹ include, for example, the carbon number exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by the R ^{5 to} R ^8. Examples thereof include the same groups as 1 to 20 monovalent hydrocarbon groups.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ⁹ include a part of hydrogen atoms included in the group exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms. Or the group etc. which all were substituted by the fluorine atom are mentioned.

  Preferred groups represented by the above formulas (iii) to (v) include the following formulas (iii-1) to (iii-4) as the above formula (iii), and the following formulas (iv−) as the above formula (iv): 1) includes the following formulas (v-1) to (v-3) as the above formula (v).

  Among these, formula (iii-1), formula (iii-2), formula (iv-1), and formula (v-3) are more preferable.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^a1 and R ^a2 include, for example, an alkyl group having 1 to 20 carbon atoms and a monovalent alicyclic hydrocarbon having 3 to 20 carbon atoms. Groups, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, and the like.

Examples of the monovalent alicyclic hydrocarbon group having an alkyl group and 3 to 20 carbon atoms having 1 to 20 carbon atoms include monovalent organic having 1 to 20 carbon atoms represented by ^R 5 to R ⁸ The same groups and the like as those exemplified for the alkyl group and alicyclic hydrocarbon group shown in the explanation of the group can be applied.

  Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, a biphenyl group, a terphenyl group, a benzyl group, and a naphthyl group.

A in the above formula (i) is preferably —SO ₂ —O— * or —NO—O— *, and the group represented by the above formula (i) is a group represented by the following formula: preferable.

In said formula, R < ¹ > is synonymous with Formula (i). By setting A in the formula (i) to —SO ₂ —O— * or —NO—O— *, the [A] polymer becomes an alkaline developer due to the high acidity of the acid generated by dissociation of the alkali dissociable group. Therefore, development defects can be further reduced.

  The structural unit (I) is preferably a structural unit represented by the above formula (1). [A] Since the polymer has the specific structural unit (I), development defects can be reduced and a resin component excellent in storage stability can be provided.

In said formula (1), R < ¹ > and A are synonymous with the said formula (i). X is a single bond or a C1-C20 divalent chain hydrocarbon group. However, some or all of the hydrogen atoms of the chain hydrocarbon group may be substituted with fluorine atoms. R ² is a single bond, a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ³ represents an (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, or an (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms and —CO—, —COO—, —OCO—, —O—. , —NR—, —CS—, —S—, —SO—, and —SO ₂ —, and a combination of at least one group selected from the group consisting of —SO ₂ —. However, when n is 1, R ³ may be a single bond. Further, part or all of the hydrogen atoms of the (n + 1) -valent hydrocarbon group may be substituted with fluorine atoms. E is a single bond, an oxygen atom, -CO-O- * or -CO-NH- *. * Indicates a binding site between the ^{R 3.} R ⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. n is an integer of 1 to 3. When n is 2 or more, the plurality of R ¹ , A, X, and R ² may be the same or different.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms represented by X and R ² include a methylene group, an ethylene group, a 1,3-propylene group, a 1,2-propylene group, 1, 1-propylene group, 2,2-propylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1 , 4-butylene group, 2-methyl-1,4-butylene group and the like. The term “chain hydrocarbon group” means a hydrocarbon group that does not include a cyclic structure in the main chain and is composed only of a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. including.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ² include, for example, monocyclic hydrocarbon groups such as cyclobutylene group, cyclopentylene group, and cyclooctylene group; norbornylene And a polycyclic hydrocarbon group such as an adamantylene group.

Examples of the (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms represented by R ³ include, for example, a linear or branched (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, the number of carbon atoms, Examples thereof include 3 to 20 (n + 1) -valent alicyclic hydrocarbon groups and (n + 1) -valent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

  Examples of the linear or branched (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms include, for example, a hydrogen atom from a linear or branched monovalent alkyl group having 1 to 20 carbon atoms. Examples include groups excluded.

  Examples of the linear or branched alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2 methylpropyl group, and a 1-methyl group. A propyl group, a t-butyl group, etc. are mentioned.

  The (n + 1) -valent alicyclic hydrocarbon group having 3 to 20 carbon atoms is a group obtained by removing n hydrogen atoms from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

  Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group.

  The (n + 1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms is a group obtained by removing n hydrogen atoms from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

  Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, and a naphthyl group.

  As said structural unit (I), the structural unit represented by a following formula is preferable.

In said formula, R < ¹ >, R < ⁴ > and A are synonymous with the said Formula (1).

  [A] As a content rate of structural unit (I) with respect to all the structural units in a polymer, 10 mol%-100 mol% are preferable, and 20 mol%-98 mol% are more preferable. By setting the content ratio of the structural unit (I) in the above specific range, high water repellency is exhibited during immersion exposure, and sufficient solubility in an alkaline developer can be ensured during development. .

[Structural unit (II)]
[A] The polymer may have a structural unit (II) represented by the following formula (2). [A] Since the polymer has the structural unit (II), the shape of the resist pattern after development can be further improved.

  In said formula (2), R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y is an acid dissociable group.

  The acid dissociable group represented by Y is preferably a group represented by the following formula (Y-1).

In the above formula (Y-1), R ^b1 , R ^b2 and R ^b3 are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. . R ^b2 and R ^b3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms together with the carbon atom to which they are bonded.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^b1 , R ^b2 and R ^b3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methyl. A propyl group, a 1-methylpropyl group, a t-butyl group, etc. are mentioned.

Together with the monovalent aliphatic cyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^b1 , R ^b2 and R ^b3 , and the carbon atom to which R ^b2 and R ^b3 are bonded to each other Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms formed include a bridged skeleton such as an adamantane skeleton and a norbornane skeleton, and a monocyclic cycloalkane skeleton such as cyclopentane and cyclohexane. Group; these groups are, for example, one or more of linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group and i-propyl group. And groups having an alicyclic hydrocarbon skeleton such as a group substituted with.

  Among these, a group having a monocyclic cycloalkane skeleton is preferable in that the shape of the resist pattern after development can be further improved.

  Examples of the structural unit (II) include structural units represented by the following formulas (2-1) to (2-7).

In said formula (2-1)-(2-7), R is synonymous with Formula (2). R ^b1 , R ^b2 and R ^b3 have the same ^meaning as in formula (Y-1). Each r is independently an integer of 1 to 3.

As a content rate of the said structural unit (II), 70 mol% or less is preferable with respect to all the structural units in a [A] polymer, 5 mol%-90 mol% are more preferable, 5 mol%-80 mol% are Particularly preferred. By making the content rate of structural unit (II) into the said specific range, the shape of the resist pattern after image development can be improved further.
[Structural unit (III)]
[A] The polymer may have a structural unit (III) represented by the following formula (3). [A] When the polymer has the structural unit (III), the affinity for the developer can be improved.

In said formula (3), R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^L1 is a single bond or a divalent linking group. R ^Lc is a monovalent organic group having a lactone structure, a monovalent organic group having a sultone structure, or a monovalent organic group having a cyclic carbonate structure.

Examples of the divalent linking group represented by R ^L1, and examples thereof include divalent hydrocarbon group having 1 to 20 carbon atoms. Examples of the divalent hydrocarbon group of 1 to 20 carbon atoms, for example, divalent said ^R 5 carbon atoms exemplified in the monovalent organic group having 1 to 20 carbon atoms represented by to R ⁸ 1-20 A group similar to the hydrocarbon group can be applied.

  Examples of the structural unit (III) include structural units having a lactone structure represented by the following formulas (3-1) to (3-9), and represented by the following formulas (3-10) to (3-21). And structural units having a cyclic carbonate structure represented by the following formulas (3-22) to (3-30), and the like.

  In said formula, R is synonymous with Formula (3). In these, the structural unit represented by Formula (3-1), (3-9) and Formula (3-22) is preferable.

  As a content rate of the said structural unit (III), 50 mol% or less is preferable with respect to all the structural units in a [A] polymer, 40 mol% or less is more preferable, and 5-30 mol% is especially preferable. By making the content rate of the said structural unit (III) into the said specific range, the affinity with respect to a developing solution can be improved effectively.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (III) as long as the effects of the present invention are not impaired.

  [A] The content of the polymer is usually 0.1% by mass to the total polymer of the [A] polymer in the composition and the other polymer contained as necessary. It is 20 mass%, 0.5 mass%-15 mass% are preferable, and 1 mass%-10 mass% are more preferable. [A] If the content of the polymer is less than 0.1% by mass, there may be a local unevenness in the water repellency of the resist film. Since the difference in dissolution of the resist film becomes small, the shape of the resist pattern may be deteriorated.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. For example, (1) a method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction, (2) a solution containing the monomer and radical initiation A solution containing an agent separately from a solution containing a reaction solvent or a monomer, and a polymerization reaction, (3) a plurality of types of solutions containing each monomer, and a radical initiator A solution containing a monomer and a radical initiator in a solvent-free or reaction solvent. It is preferable to synthesize by a polymerization reaction method or the like.

  In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the monomer amount in the dropped monomer solution is 30 mol with respect to the total amount of monomers used for polymerization. % Or more, more preferably 50 mol% or more, and particularly preferably 70 mol% or more.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 degreeC-150 degreeC, 40 degreeC-150 degreeC is preferable, and 50 degreeC-140 degreeC is more preferable. Although dripping time changes with conditions, such as reaction temperature, the kind of initiator, and the monomer made to react, it is 30 minutes-8 hours normally, 45 minutes-6 hours are preferable, and 1 hour-5 hours are more preferable. Also, the total reaction time including the dropping time varies depending on the conditions as in the dropping time, but is usually 30 minutes to 12 hours, preferably 45 minutes to 12 hours, and more preferably 1 to 10 hours.

  Examples of the radical initiator used in the polymerization include 2,2′-azobis (2-isobutyronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2 , 2'-azobis (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-isobutyronitrile), dimethyl 2, Azo radical initiators such as 2′-azobis (2-methylpropionate); peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like. Among these, 2,2'-azobis (2-isobutyronitrile) and dimethyl 2,2'-azobis (2-isobutyronitrile) are preferable. In addition, you may use a radical initiator individually or in combination of 2 or more types.

  As a reaction solvent, any solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, etc.) and capable of dissolving the monomer may be used. it can. Examples thereof include alcohols, ethers, ketones, amides, esters / lactones, nitriles, and mixed solvents thereof. These solvents may be used alone or in combination of two or more.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after the polymerization reaction is completed, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes may be used alone or in combination of two or more. In addition to the reprecipitation method, the polymer can be recovered by removing low molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000 to 50,000, more preferably 1,000 to 40,000, and 1,000 to 30. Is particularly preferred. [A] If the Mw of the polymer is less than 1,000, there is a possibility that sufficient water repellency may not be exhibited during immersion exposure. On the other hand, if the Mw of the [A] polymer exceeds 50,000, the developability of the resist film may be lowered.

  [A] The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1.0 to 5.0, preferably 1.0 to 4.0. 0-2.0 is more preferable.

<[B] Acid generator>
[B] The acid generator is a radiation-sensitive component that generates an acid upon exposure to radiation. When the composition contains the [B] acid generator, a carboxyl group generated by dissociating an acid-dissociable group or the like of a polymer such as a [C] polymer described later by the action of an acid generated by exposure. The above-mentioned polymer in the exposed area becomes easily soluble in the developer due to the polarity such as. As the form of inclusion of the [B] acid generator constituting the composition, the following compound form (hereinafter also referred to as “[B] acid generator” as appropriate) is incorporated as part of the polymer. Either of these forms may be used. In addition, you may use a [B] acid generator individually or in combination of 2 or more types.

  [B] Specific examples of the acid generator include compounds described in paragraphs [0080] to [0113] of JP-A-2009-134088, and examples thereof include iodonium salts, sulfonium salts, and tetrahydrothiophenium. Preferred are onium salt compounds such as salts and sulfonic acid compounds.

[B] As the acid generator, specifically,
Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t- Butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate;

  Examples of sulfonium salts include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, cyclohexyl, 2-oxocyclohexyl, methylsulfonium trifluoromethanesulfonate, dicyclohexyl, 2- Oxocyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldimethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate;

  As tetrahydrothiophenium salt, 4-hydroxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate, 4-hydroxy-1-naphthyltetrahydrothiophenium nonafluoro-n-butanesulfonate, 4-hydroxy-1-naphthyltetrahydrothio Phenium perfluoro-n-octane sulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium Lifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium per Fluoro-n-octane sulfonate;

  As sulfonic acid compounds, trifluoromethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2. , 3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide Nonafluoro-n-butane sulfonate, N-hydroxysuccinimide perfluoro-n-octane sulfonate, 1,8-naphthalenedicarboxylic imide trifluoromethane sulfonate are preferred.

  [B] The content of the acid generator is 0.1 to 30 parts by mass with respect to 100 parts by mass of the total amount of the polymer contained in the composition from the viewpoint of ensuring sensitivity and developability as a resist. It is preferable that it is 0.1 mass part-20 mass parts. [B] If the content of the acid generator is less than 0.1 parts by mass, the sensitivity and developability tend to be lowered. On the other hand, if it exceeds 30 parts by mass, the transparency to radiation tends to decrease, and it becomes difficult to obtain a rectangular resist pattern.

<[C] polymer>
The [C] polymer is a polymer having a fluorine atom content smaller than that of the [A] polymer, and has an acid dissociable group. [C] The polymer has an acid dissociable group, so that the sensitivity of the composition to radiation can be improved, and the fluorine atom content of the [C] polymer is smaller than that of the [A] polymer. Thus, [A] the degree of uneven distribution of the polymer in the surface layer of the resist film can be increased, and the water repellency with respect to the immersion exposure liquid during the immersion exposure can be further improved. [C] The fluorine atom content of the polymer is preferably less than 5% by mass, more preferably 3% by mass or less, and even more preferably 1% by mass or less. The fluorine atom content can be calculated from this structure by identifying the structure of the polymer using ¹³ C-NMR.

  The specific structure of the [C] polymer is not particularly limited as long as it satisfies the above configuration, but it is preferable to have the structural unit (II) represented by the above formula (2) for the [A] polymer. In addition, the [C] polymer has the structural unit (III) represented by the above formula (3) and other structural units for the [A] polymer as long as the effects of the present invention are not impaired. Also good. In addition, the [C] polymer may have 2 or more types of each structural unit.

[Structural unit (II)]
As a content rate of the said structural unit (II), 5 mol%-90 mol% are preferable with respect to all the structural units in a [C] polymer, 10 mol%-80 mol% are more preferable, 20 mol%-70 mol%. Mole% is particularly preferred. By making the content rate of the said structural unit (II) into the said specific range, the sensitivity with respect to a radiation can be improved more and the shape of the resist pattern after image development can be improved effectively.

[Structural unit (III)]
As a content rate of the said structural unit (III), 80 mol% or less is preferable with respect to all the structural units in a [C] polymer, 60 mol% or less is more preferable, and 10-50 mol% is especially preferable. By making the content rate of the said structural unit (III) into the said specific range, the affinity with respect to a developing solution can be improved effectively.

[Other structural units]
[C] The polymer may have other structural units other than the structural units (II) and (III) as long as the effects of the present invention are not impaired.

  [C] When the polymer is contained, the content is usually 70% by mass or more and preferably 80% by mass or more with respect to the total solid content in the composition. If the content is less than 70% by mass, the resolution performance of the resist pattern may deteriorate.

<[C] Polymer Synthesis Method>
[C] The polymer can be produced, for example, by polymerizing monomers corresponding to each structural unit in a suitable solvent using a radical polymerization initiator. As a method for synthesizing the [C] polymer, since the same method as that for the [A] polymer can be applied, detailed description thereof is omitted.

  [C] The Mw of the polymer is usually 3,000 to 300,000, preferably 4,000 to 200,000, and more preferably 4,000 to 100,000. If the Mw is less than 3,000, the heat resistance of the resist film may be lowered, and if the Mw exceeds 300,000, the developability may be lowered.

  [C] The ratio of Mw to Mn (Mw / Mn) of the polymer is usually 1.0 to 5.0, preferably 1.0 to 4.0, and more preferably 1.0 to 2.0.

<[D] Acid diffusion controller>
The resist composition for immersion exposure according to the present invention preferably further contains a [D] acid diffusion controller. [D] As the acid diffusion controller, for example, a compound represented by the following formula (4) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”) , "Nitrogen-containing compound (II)", compounds having 3 or more nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. Can be mentioned. When the said composition contains a [D] acid diffusion control body, while being able to improve a resist pattern shape, the storage stability of the said composition can be improved more. [D] The content of the acid diffusion controller in the composition may be an acid diffusion controller (hereinafter also referred to as “[D] acid diffusion controller” as appropriate) which is a compound as described below. It may be in the form of an acid diffusion control group incorporated as a part of another polymer such as a polymer or a [C] polymer, or in both forms.

In said formula (4), R < ¹⁰ > -R < ¹² > is respectively independently a hydrogen atom, the linear, branched or cyclic alkyl group, aryl group, or aralkyl group which may be substituted.

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. Can be mentioned.

  Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and the like.

  Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N -T-amyloxycarbonyl-4-hydroxypiperidine and the like.

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like. .

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine, pyrazine, pyrazole, N- (undecylcarbonyloxyethyl) morpholine, and the like.

  Further, as the [D] acid diffusion controller, a nitrogen-containing organic compound having an acid dissociable group can also be used. Examples of the nitrogen-containing organic compound having such an acid dissociable group include N- (t-butoxycarbonyl) piperidine, N- (t-butoxycarbonyl) imidazole, N- (t-butoxycarbonyl) benzimidazole, N -(T-butoxycarbonyl) -2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) diphenylamine, N- (t-butoxycarbonyl) -4-hydroxypiperidine and the like can be mentioned.

  [D] As the acid diffusion controller, a compound represented by the following formula (5) can also be used.

In the above formula (5), X ⁺ is a cation represented by the following formula (5-1-1) or (5-1-2). Z ^{- is,} OH ^-, R D1 -COO ^- anion represented ^by, R D1 -SO ₃ ^- anionic or ^R D1 ^-N represented by - is an anion represented by _-SO 2 ^{-R D2.} R ^D1 represents an optionally substituted alkyl group, a monovalent aliphatic cyclic hydrocarbon group, or an aryl group. R ^D2 is an alkyl group or a monovalent alicyclic hydrocarbon group in which some or all of the hydrogen atoms are substituted with fluorine atoms.

In the formula (5-1-1), R ^{D3 to} R ^D5 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom. In the above formula (5-1-2), R ^D6 and R ^D7 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom.

  The above compound is used as an acid diffusion control agent that is decomposed by exposure and loses acid diffusion controllability (hereinafter also referred to as “photodegradable acid diffusion control agent”). When the composition contains the photodegradable acid diffusion controller, the acid is diffused in the exposed area, and the acid diffusion is controlled in the unexposed area, whereby the contrast between the exposed area and the unexposed area is excellent ( In other words, the boundary portion between the exposed portion and the unexposed portion becomes clear), which is effective for improving the resolution performance of the resist pattern and further enhances the storage stability of the composition.

X ⁺ in the above formula (5) is a cation represented by the above formula (5-1-1) or (5-1-2). R ^{D3 to} R ^D5 in the above formula (5-1-1) are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom, and among these, a developer solution of the above compound is used. A hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom are preferable because of the effect of reducing solubility. In addition, R ^D6 and R ^D7 in the above formula (5-1-2) are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom, and among these, a hydrogen atom, an alkyl group, A halogen atom is preferred.

^Z in the above formula (5) in - ^is, OH ^-, R D1 -COO ^- in _-SO 2 ^{-R D2} - anion represented ^by, R D1 -SO ₃ ^- anionic or formula represented by ^R D1 ^-N An anion represented. However, R ^D1 in these formulas is an optionally substituted alkyl group, alicyclic hydrocarbon group or aryl group, and among these, there is an effect of reducing the solubility of the above compound in a developer. Therefore, an alicyclic hydrocarbon group or an aryl group is preferable.

  Examples of the optionally substituted alkyl group in the above formula (5) include a hydroxyalkyl group having 1 to 4 carbon atoms such as a hydroxymethyl group; an alkoxyl group having 1 to 4 carbon atoms such as a methoxy group; a cyano group; And a group having one or more substituents such as a cyanoalkyl group having 2 to 5 carbon atoms such as a cyanomethyl group. Among these, a hydroxymethyl group, a cyano group, and a cyanomethyl group are preferable.

  Examples of the optionally substituted alicyclic hydrocarbon group in the above formula (5) include monocyclic cycloalkane skeletons such as hydroxycyclopentane, hydroxycyclohexane, and cyclohexanone; 1,7,7-trimethylbicyclo [2 2.1] monovalent groups derived from alicyclic hydrocarbons such as a bridged alicyclic hydrocarbon skeleton such as heptan-2-one (camphor). Among these, a group derived from 1,7,7-trimethylbicyclo [2.2.1] heptan-2-one is preferable.

  Examples of the aryl group which may be substituted in the above formula (5) include, for example, a phenyl group, a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylcyclohexyl group, and a part or all of hydrogen atoms of these groups. Are substituted with a hydroxy group, a cyano group, or the like. Among these, a phenyl group, a hydroxyphenyl group, a benzyl group, or a phenylcyclohexyl group is preferable.

Z in the above formula (5) ^- is an anion represented by the following formula (5-2-1) ^{(R D1} is ^R D1 -COO a 2-hydroxyphenyl group ^- anion represented by), the following formula ( 5-2-2) represented by an anion (R ^D1 is a group derived from 1,7,7-trimethylbicyclo [2.2.1] heptan-2-one, R ^D1 —SO ₃ ^—. Anion) or an anion represented by the following formula (5-2-3) (R ^D1 is a butyl group and R ^D2 is a trifluoromethyl group, and is represented by R ^D1 —N ^— SO ₂ —R ^D2 Anion) is preferable.

  The photodegradable acid diffusion controller is represented by the above formula (5), and specifically, it is preferably a sulfonium salt compound or an iodonium salt compound that satisfies the above conditions.

  Examples of the sulfonium salt compound include triphenylsulfonium hydroxide, triphenylsulfonium salicylate, triphenylsulfonium 4-trifluoromethyl salicylate, diphenyl-4-hydroxyphenylsulfonium salicylate, triphenylsulfonium 10- Examples include camphor sulfonate, 4-t-butoxyphenyl diphenylsulfonium 10-camphor sulfonate, and the like. Among these, triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are more preferable. In addition, you may use these sulfonium salt compounds individually or in combination of 2 or more types.

Examples of the iodonium salt compound include bis (4-t-butylphenyl) iodonium hydroxide, bis (4-t-butylphenyl) iodonium salicylate, and bis (4-t-butylphenyl) iodonium 4-trifluoro. Examples thereof include methyl salicylate and bis (4-t-butylphenyl) iodonium 10-camphorsulfonate. In addition, you may use these iodonium salt compounds individually or in combination of 2 or more types.

  [D] The acid diffusion controller is preferably a photodegradable acid diffusion controller. [D] Since the acid diffusion controller is a photodegradable acid diffusion controller, the storage stability of the composition can be further enhanced. [D] The acid diffusion controller may be used alone or in combination of two or more.

[D] The content of the acid diffusion controller is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and more preferably 10 parts by mass or less with respect to 100 parts by mass of the total amount of the polymer contained in the composition. More preferred is 5 parts by mass or less. [D] If the acid diffusion controller is excessively contained, the sensitivity of the formed resist film may be significantly lowered.

<[E] solvent>
[E] The solvent is a component usually contained in the resist composition for immersion exposure according to the present invention. [E] As solvent, dissolve or disperse [A] polymer and [B] acid generator, and optional components such as [C] polymer and [D] acid diffusion controller contained as necessary. If it is possible, there is no particular limitation. In addition, you may use [E] solvent individually or in mixture of 2 or more types.

[E] As the solvent, for example,
Linear or branched ketones such as 2-pentanone, 2-hexanone, 2-heptanone, 2-octanone;
Cyclic ketones such as cyclopentanone and cyclohexanone;
Propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate;
Ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate;
Propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and propylene glycol monoethyl ether;
Ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether;
Diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether;
Alkyl 2-hydroxypropionates such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate;
Alkyl 3-alkoxypropionates such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate;
Esters such as diethyl carbonate, propylene carbonate, acid methyl, ethyl acetate, n-butyl acetate, methyl pyruvate, ethyl pyruvate, γ-butyrolactone, γ-valerolactone;
Etc.

  Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ethers, alkyl 2-hydroxypropionate and alkyl 3-alkoxypropionate are included. Propylene glycol monomethyl ether acetate, γ-butyrolactone, and cyclohexanone are more preferable.

<Other optional components>
The resist composition for immersion exposure may contain other optional components such as an uneven distribution accelerator and a surfactant as long as the effects of the present invention are not impaired. Other optional components may be used alone or in combination of two or more. Further, the content of other optional components can be appropriately determined according to the purpose.

(Uniformity promoting agent)
The uneven distribution promoter has the effect of causing the [A] polymer to segregate on the resist film surface more efficiently. When the said composition contains this uneven distribution promoter, the addition amount of a [A] polymer can be decreased rather than before. Accordingly, it is possible to further suppress the elution of components from the resist film to the immersion exposure liquid without impairing general characteristics such as sensitivity and LWR, or to perform immersion exposure at a higher speed by high-speed scanning.

  Examples of such an uneven distribution promoter include low molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point of 100 ° C. or more at 1 atm. Specific examples of the compound include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.
Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.
Examples of the nitrile compound include succinonitrile.
Examples of the polyhydric alcohol include glycerin.

  10 mass parts-500 mass parts are preferable with respect to 100 mass parts of total amounts of the polymer contained in the said composition, and, as for content of the said uneven distribution promoter, 30 mass parts-300 mass parts are more preferable. In addition, you may use the said uneven distribution promoter individually or in combination of 2 or more types.

(Surfactant)
A surfactant is a component that improves coating properties and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol In addition to nonionic surfactants such as distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (manufactured by Tochem Products), Megafuck F171, F173 (manufactured by Dainippon Ink and Chemicals), Fluorard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Examples include Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (manufactured by Asahi Glass).

  Content of the said surfactant is 2 mass parts or less normally with respect to 100 mass parts of total amounts of the polymer contained in the said composition. In addition, you may use the said surfactant individually or in combination of 2 or more types.

<Preparation of resist composition for immersion exposure>
The resist composition for immersion exposure of the present invention is usually dissolved in an [E] solvent so that the total solid content concentration is 1% by mass to 50% by mass, preferably 1% by mass to 25% by mass. It is prepared by filtering with a filter having a pore diameter of about 5 nm. The material of the filter is not particularly limited, and examples thereof include nylon 6, 6, nylon 6, polyethylene, or a combination thereof.

  In addition, the said resist composition for immersion exposure is so preferable that there is little content of impurities, such as a halogen ion and a metal. When the content of such impurities is small, the sensitivity, resolution, process stability, pattern shape and the like of the resist film can be further improved. Therefore, the polymer such as the [A] polymer and the [C] polymer contained in the composition is, for example, a chemical purification method such as washing with water, liquid-liquid extraction or the like, or these chemical purification methods and ultrafiltration. It is preferable to purify by a combination with a physical purification method such as centrifugation.

<Method for forming resist pattern>
The method for forming a resist pattern using the resist composition for immersion exposure is usually as follows:
(1) A step of applying a resist composition for immersion exposure on a substrate to form a resist film;
(2) A step of placing an immersion exposure liquid on the resist film, irradiating the resist film with radiation through the immersion exposure liquid, and immersion exposure of the resist film; and (3) the immersion exposure. A step of developing the resist film with a developer to form a resist pattern.

[Step (1)]
In this step, the resist composition for immersion exposure of the present invention is applied onto a substrate to form a resist film.

  Examples of the substrate include a silicon wafer and a wafer coated with aluminum. A resist film is formed by applying the composition on the substrate. The method for applying the composition is not particularly limited, and for example, it can be applied by a known method such as a spin coating method. When applying the composition, the amount of the composition to be applied is adjusted so that the resist film to be formed has a desired thickness. In addition, after apply | coating the said composition on a board | substrate, in order to volatilize a solvent, you may pre-bake (henceforth "PB"). The prebaking heating temperature is usually 30 ° C to 200 ° C, preferably 50 ° C to 150 ° C.

[Step (2)]
In this step, an immersion exposure liquid is disposed on the resist film formed in the above step (1), and the resist film is irradiated with radiation through the immersion exposure liquid, and the resist film is subjected to immersion exposure. .

  As the immersion exposure liquid, a liquid having a higher refractive index than air is usually used. Specific examples include pure water, long chain or cyclic aliphatic compounds, and the like. In this state through the immersion exposure liquid, that is, in a state where the immersion exposure liquid is filled between the lens and the resist film, the exposure apparatus irradiates radiation, and the resist film is formed through a mask having a predetermined pattern. Exposure.

  The radiation is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams and the like according to the type of acid generator used. Among these, ArF excimer laser light ( Far ultraviolet rays typified by a wavelength of 193 nm) and KrF excimer laser light (wavelength 248 nm) are preferred, and ArF excimer laser light (wavelength 193 nm) is more preferred. In addition, exposure conditions, such as exposure amount, can be suitably selected according to the compounding composition of the resist composition for immersion exposure, the kind of additive, etc.

  In the present invention, it is preferable to perform heat treatment (PEB) after exposure. By this PEB, the dissociation reaction of the acid dissociable group in the resin component can be smoothly advanced. The heating conditions for PEB are appropriately adjusted depending on the composition of the resist composition for immersion exposure, but are usually 30 ° C to 200 ° C, preferably 50 ° C to 170 ° C.

  In order to maximize the potential of the resist composition for immersion exposure, it is used, for example, as disclosed in Japanese Patent Publication No. 6-12452 (Japanese Patent Laid-Open No. 59-93448). An organic or inorganic antireflection film can also be formed on the substrate. Further, in order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film can be provided on the resist film as disclosed in, for example, JP-A-5-188598.

[Step (3)]
In this step, the resist film subjected to immersion exposure in step (2) is developed with a developer to form a resist pattern.

  Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl Diethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3 0.0] -5-Nonene, an alkaline aqueous solution in which at least one alkaline compound is dissolved is preferable. For example, a suitable amount of a water-soluble organic solvent such as alcohols such as methanol and ethanol, and a surfactant can be added to the developer.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. The measuring method of various physical property values is shown below.

[Weight average molecular weight (Mw), number average molecular weight (Mn)]
Using Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL), flow rate: 1.0 ml / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C., with monodisperse polystyrene as standard Measured by gel permeation chromatography (GPC).

[ ¹ H-NMR analysis, ¹³ C-NMR analysis]
The ¹ H-NMR analysis of the compound and the ¹³ C-NMR analysis for determining the fluorine atom content of each polymer were performed using a nuclear magnetic resonance apparatus (“JNM-ECP500” manufactured by JEOL Ltd.).
[Mass Spectrometry Analysis]
Mass spectrometric analysis of the compounds was performed using GC-MS (Agilent Technology, 7890A GC, 240MS system).

<Synthesis of compounds>
[A] Synthesis examples of the compounds (M-1) to (M-7) used for polymer synthesis are shown below.
[Synthesis Example 1] (Synthesis of Compound (M-1))
In a 300 ml three-necked flask purged with nitrogen, put 2.84 g of 3- (methacryloyloxy) -1,1,1-trifluoropropan-2-ylsulfonic acid sodium salt in a mixed solvent of 20 ml of tetrahydrofuran and 20 ml of dichloromethane. The suspension was made 0 ° C. in an ice bath. While stirring the suspension with a stirrer, 1.52 g of oxalyl chloride was added over 10 minutes, and then 0.1 g of N, N-dimethylformamide was added. Thereafter, the reaction solution was slowly heated to 23 ° C. and stirred for 1 hour. The reaction solution was suction filtered to remove the solid content, and the filtrate was concentrated with an evaporator. 30 ml of dichloromethane was added to the concentrate, 5 g of sodium sulfate was added, and the mixture was stirred for 30 minutes and suction filtered. The filtrate was concentrated with an evaporator. The concentrated solution was transferred to a 300 ml three-necked flask purged with nitrogen, and 20 ml of dried dichloromethane was added and dissolved therein, and the temperature was adjusted to 0 ° C. in an ice bath. Thereto was added a solution of 0.73 g of acetone oxime in 20 ml of dichloromethane over 5 minutes, and then 1.21 g of triethylamine was added over 20 minutes. The reaction was stirred at 0 ° C. for 2 hours. After completion of the reaction, 30 ml of 1N hydrochloric acid was added to the reaction solution, transferred to a separatory funnel, and the organic layer was recovered by a liquid separation operation. The organic layer was washed 3 times with pure water and concentrated with an evaporator to obtain 1.87 g of compound (M-1) (yield 59%).

(Physical properties of compound (M-1))
¹ H-NMR analysis (measuring solvent: CDCl ₃ , reference substance: tetramethylsilane):
σ = 6.12 (s, 1H, ═CH ₂ ), 5.90 (m, 1H, CH), 5.60 (s, 1H, ═CH ₂ ), 4.45 (m, 2H, CH ₂ ) , 2.05 (s, 3H, CH ₃ ), 1.95 (s, 3H, CH ₃ ), 1.90 (s, 3H, CH ₃ )
Mass spectrometry analysis (ionization method: methanol CI): m / z 318 [M + H] ⁺ , 248, 245, 232

[Synthesis Examples 2 to 7] (Synthesis of Compounds (M-2) to (M-7))
In the same manner as the synthesis of compound (M-1), the corresponding amount of the same sulfonate was used instead of 3- (methacryloyloxy) -1,1,1-trifluoropropan-2-ylsulfonic acid sodium salt. The corresponding compound was synthesized using the same amount of the substance instead of acetone oxime.
Yield: Compound (M-2): 38%, Compound (M-3): 67%, Compound (M-4): 33%, Compound (M-5): 50%, Compound (M-6) : 69%, Compound (M-7): 70%.

(Physical properties of compound (M-2))
¹ H-NMR analysis (measuring solvent: DMSO, reference material: tetramethylsilane):
σ = 6.19 (s, 1H, ═CH ₂ ), 6.00 (m, 1H, CH), 5.83 (s, 1H, ═CH ₂ ), 2.10 (s, 3H, CH ₃ ) , 1.98 (s, 3H, CH ₃ ), 1.89 (s, 3H, CH ₃ )
Mass spectrometric analysis (ionization method: methanol CI): m / z 354 [M + H] ⁺ , 284, 281, 268

(Physical properties of compound (M-3))
¹ H-NMR analysis (measuring solvent: CDCl ₃ , reference substance: tetramethylsilane):
σ = 6.14 (s, 1H, ═CH ₂ ), 5.64 (s, 1H, ═CH ₂ ), 5.28 (
2.10 (s, 3H, CH ₃ ), 1.98 (s, 3H, CH ₃ ), 1.89 (s, 3H, CH ₃ )
Mass spectrometric analysis (ionization method: methanol CI): m / z 354 [M + H] ⁺ , 284, 281, 268

(Physical properties of compound (M-4))
¹ H-NMR analysis (measuring solvent: DMSO, reference material: tetramethylsilane):
σ = 6.19 (s, 1H, ═CH ₂ ), 6.00 (m, 1H, CH), 5.83 (s, 1H, ═CH ₂ ), 2.13 (s, 3H, CH ₃ ) , 1.89 (s, 3H, CH ₃ )
Mass spectrometric analysis (ionization method: methanol CI): m / z 408 [M + H] ⁺ , 338, 322, 281

(Physical properties of compound (M-5))
¹ H-NMR analysis (measuring solvent: CDCl ₃ , reference substance: tetramethylsilane):
σ = 6.11 (s, 1H, ═CH ₂ ), 5.63 (s, 1H, ═CH ₂ ), 4.30 (t, 2H, O—CH ₂ ), 3.44 (t, 2H, _{SO 2 CH 2), 2.34 (} m, 2H, CH 2), 1.95 (s, 3H, CH 3)
Mass spectrometry analysis (ionization method: methanol CI): m / z 427 [M + H] ⁺ , 357, 341, 191,

(Physical properties of compound (M-6))
¹ H-NMR analysis (measuring solvent: CDCl ₃ , reference substance: tetramethylsilane):
σ = 7.90 (d, 2H, C ₆ H ₄ ), 7.58 (d, 2H, C ₆ H ₄ ), 6.78 (dd, 1H, = CH), 5.96 (d, 1H, _{= CH 2), 5.53 (d} , 1H, CH 2), 5.27 (m, 1H, O-CH)
Mass spectrometry analysis (ionization method: methanol CI): m / z 334 [M + H] ⁺ , 167, 151

(Physical properties of compound (M-7))
¹ H-NMR analysis (measuring solvent: CDCl ₃ , reference substance: tetramethylsilane):
σ = 7.96 (d, 2H, C ₆ H ₄ ), 7.58 (d, 2H, C ₆ H ₄ ), 6.78 (dd, 1H, = CH), 5.94 (d, 1H, = CH ₂ ), 5.50 (d, 1H, CH ₂ ), 2.13 (s, 1H, CH ₃ )
Mass spectrometry analysis (ionization method: methanol CI): m / z 294 [M + H] ⁺ , 167, 110

<[A] Synthesis of polymer>
Each polymer was synthesize | combined using the compound represented by following formula (M-1)-(M-21). In addition, what was synthesize | combined in the said synthesis examples 1-7 was used for the compounds (M-1)-(M-7) used for the synthesis | combination of a polymer. Table 1 shows the Mw, Mw / Mn, and fluorine atom content of each polymer.

[Synthesis Example 8] (Synthesis of Polymer (A-1))
12.99 g of compound (M-1) and 2.01 g of compound (M-8) are dissolved in 30 g of 2-butanone, and 0.42 g of 2,2′-azobis (2-isobutyronitrile) is further added to 100 mL. Into a three-necked flask. After purging with nitrogen for 30 minutes, the reaction kettle was heated to 80 ° C. with stirring, the start of overheating was taken as the polymerization start time, and the polymerization reaction was conducted for 6 hours. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or less, and concentrated under reduced pressure until the weight of the polymerization solution became 12.5 g using an evaporator. The polymerization solution was slowly added to 75 g of n-hexane cooled to 0 ° C. to precipitate a solid content. The mixture was decanted to remove the liquid, the solid was washed 3 times with n-hexane, and the resulting resin was vacuum dried at 40 ° C. for 15 hours. 11.25 g (yield 75%) of white powdery polymer (A-1) was obtained. Mw of this polymer (A-1) was 9,400, and Mw / Mn was 1.50.

[Synthesis Example 9] to [Synthesis Example 22] (Synthesis of Polymers (A-2) to (A-12) and Polymers (a-1) to (a-3))
Each polymer was synthesized in the same manner as in Synthesis Example 8 except that the types and amounts of compounds (monomers) shown in Table 1 were used. Table 1 also shows the yield (%), Mw, Mw / Mn, and fluorine atom content (% by mass) of each synthesized polymer. In Table 1, “-” indicates that the corresponding compound was not used.

<Synthesis of [C] polymer>
[C] polymer was synthesize | combined using the compound represented by following formula (M-22)-(M-26). [C] The yield, Mw, Mw / Mn, and fluorine atom content of the polymer are shown in Table 2.

[Synthesis Example 23] (Synthesis of Polymer (C-1))
Compound (M-22) 11.92 g, Compound (M-23) 41.07 g, Compound (M-24) 15.75 g, Compound (M-25) 11.16, Compound (M-26) 20.10 g, A monomer solution was prepared by dissolving 3.88 g of dimethyl 2,2′-azobis (2-isobutyronitrile) in 200 g of 2-butanone. On the other hand, 100 g of 2-butanone was put into a 1000 mL three-necked flask, and after purging with nitrogen for 30 minutes, the reaction kettle was heated to 80 ° C. with stirring. The said monomer solution was dripped there over 4 hours, and also it age | cure | ripened at 80 degreeC for 2 hours after completion | finish of dripping. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. The polymerization solution was concentrated under reduced pressure using an evaporator until the weight of the polymerization solution reached 200 g. Thereafter, the polymerization solution was put into 1000 g of methanol, and reprecipitation operation was performed. The precipitated slurry was filtered by suction, and the solid content was washed with methanol three times. This solid content was vacuum-dried at 60 ° C. for 15 hours to obtain 88.0 g of a white powdery polymer (C-1) (yield 88%). Mw of this polymer (C-1) was 9,300, and Mw / Mn was 1.60. As a result of ¹³ C-NMR analysis, the content of structural units derived from the compounds (M-22), (M-23), (M-24), (M-25) and (M-26) is They were 16 mol%, 26 mol%, 19 mol%, 11 mol%, and 28 mol%, respectively.

<Preparation of resist composition for immersion exposure>
The components other than the [A] polymer and the [C] polymer constituting the resist composition for immersion exposure are shown below.

[B] Acid generator Compound represented by the following formula (B-1)

[D] Acid diffusion controller A compound represented by the following formulas (D-1) to (D-4)

[E] Solvent E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 1]
[A] 5 parts by mass as polymer (A-1), [B] 8 parts by mass as acid generator, (C-1) 100 parts by mass as polymer (C-1), [D] acid (D-1) 0.6 parts by mass as a diffusion control agent, and (E-1) 1,732 parts by mass, (E-2) 743 parts by mass and (E-3) 275 parts by mass as an [E] solvent. The resist composition for immersion exposure was prepared by blending.

[Examples 2 to 18, Comparative Examples 1 to 7]
Each composition was prepared in the same manner as in Example 1 except that the type and amount (parts by mass) of each component to be blended were as shown in Table 3.

<Evaluation>
Sensitivity, LWR, development defect evaluation and storage stability were measured, and the results are shown in Table 4.
[sensitivity]
Each composition shown in Table 3 was spin-coated on a silicon wafer having a diameter of 12 inches and then soft-baked (SB) at 120 ° C. for 60 seconds to form a resist film having a thickness of 75 nm. Next, this resist film was used for pattern formation of 50 nm Line 100 nm Pitch using an ArF excimer laser immersion exposure apparatus (“NSR S610C”, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.800, Annular. Exposure was through a mask pattern. After the exposure, each resist film was post-baked (PEB) at 90 ° C. for 60 seconds. Thereafter, the resist film was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern. At this time, an exposure amount at which a portion exposed through a mask pattern for forming a pattern of 50 nm Line 100 nm Pitch forms a Line having a line width of 50 nm was defined as an optimum exposure amount (Eop). This optimum exposure amount was defined as sensitivity (mJ / cm ² ). At this time, when the sensitivity was 40 (mJ / cm ² ) or less, it was judged as “good”, and when it exceeded 40 (mJ / cm ² ), it was judged as “bad”. Note that a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, CG4000) was used for length measurement.

[LWR]
A positive resist pattern was formed by the same method as in the sensitivity (mJ / cm ² ) evaluation, and Eop was measured. The line width of 50 nm Line 100 nm Pitch formed by the above Eop was observed from the upper part of the pattern using a scanning electron microscope (manufactured by Hitachi High-Technologies, CG4000), and the line width was measured at arbitrary 10 points. The 3-sigma value (variation) of the measured line width was defined as LWR (nm). At this time, if the value of LWR was 5.4 nm or less, it was judged as “good”, and if it exceeded 5.4 nm, it was judged as “bad”.

[Development defect evaluation]
A film having a film thickness of 110 nm was formed from a photoresist composition on a 12-inch silicon wafer on which a lower antireflection film (manufactured by Nissan Chemical Industries, ARC66) was formed, and a resist film was formed by performing SB at 120 ° C. for 50 seconds. . Next, with respect to this resist film, an ArF excimer laser immersion exposure apparatus (manufactured by NIKON, NSR S610C) was used, and the line size with a target size of 45 nm was obtained under the conditions of NA = 1.3, ratio = 0.800, Dipole. It exposed through the mask pattern of space (1L / 1S). After exposure, PEB was performed at 95 ° C. for 50 seconds. Thereafter, development was performed for 10 seconds with a 2.38 mass% tetramethylammonium hydroxide aqueous solution using a GP nozzle of a developing device of Clean Electron “ACT12” manufactured by Tokyo Electron, rinsed with pure water for 15 seconds, and then shaken off at 2,000 rpm. It was dried to form a positive resist pattern. At this time, the exposure amount for forming 1 L / 1S having a width of 45 nm was determined as the optimum exposure amount. With this optimum exposure amount, 1L / 1S having a line width of 45 nm was formed on the entire surface of the wafer to obtain a defect inspection wafer. Note that a scanning electron microscope (manufactured by Hitachi High-Technologies, CC-4000) was used for length measurement. Thereafter, the number of defects on the defect inspection wafer was measured using KLA-Tencor KLA2810. Furthermore, the defects measured by the KLA2810 were classified into those judged to be derived from the resist film and those derived from the outside. After classification, the total number of defects determined to be derived from the resist film was defined as development defect evaluation. When the total number of defects is less than 100 / wafer, the development defect evaluation is “good”, when it is 100 to 500 / wafer, “slightly good”, when it exceeds 500 / wafer, “Bad”.

[Storage stability]
In each of Examples and Comparative Examples, a photoresist composition immediately after preparation and a photoresist composition after storage at 23 ° C. and stored in a dark place for 30 days were used to prepare resist films formed from these photoresist compositions. The receding contact angle was measured according to the following procedure.
(1) Formation of lower antireflection film A composition for forming an lower antireflection film (trade name “ARC66”, manufactured by Nissan Chemical Co., Ltd.) on a 12-inch silicon wafer surface, a semiconductor manufacturing apparatus (model name “Lithius Pro-i”), Spin coat using Tokyo Electron). Next, by performing pre-baking (PB) (205 ° C., 60 seconds), a lower antireflection film having a thickness of 105 nm was formed.
(2) Formation of Resist Film After the formation of the lower antireflection film, a photoresist composition was spin-coated using a semiconductor manufacturing apparatus (model name “CLEAN TRACK ACT12”, manufactured by Tokyo Electron). Then, PB (110 ° C., 60 seconds) and cooling (23 ° C., 30 seconds) were performed to form a resist film having a thickness of 100 nm.
(3) Measurement of contact angle The receding contact angle of the resist film formed above was measured in the following procedure using “DSA-10” manufactured by KRUSS in an environment of room temperature 23 ° C., humidity 45%, and normal pressure. .
First, the wafer stage position is adjusted. Next, the wafer is set on the stage. Water is injected into the “DSA-10” needle. Next, the position of the needle is finely adjusted. Next, water is discharged from the needle to form a 25 μL water droplet on the wafer, and then the needle is once pulled out of the water droplet. Next, the needle is pulled down again to the finely adjusted position. Subsequently, a water droplet is sucked with a needle at a rate of 10 μL / min for 90 seconds, and the contact angle is measured every second (total 90 times). Next, from the time when the contact angle was stabilized, an average value was calculated for a total of 20 contact angles, which were set as receding contact angles (°).

  The receding contact angle for the resist film formed from both photoresist compositions immediately after preparation and after storage for 30 days was determined, and the variation rate was defined as storage stability. At this time, when the fluctuation rate is within 3%, the storage stability is good “◯”, when it exceeds 3% and is 5% or less, it is slightly good “Δ”, and when it exceeds 5%, it is judged as “bad”. .

  As can be seen from the results shown in Table 4, the sensitivity and LWR were good evaluation results, and in the comparative example, at least one of development defect evaluation and storage stability was poor, whereas The development defect evaluation and the storage stability were both good.

  The present invention provides a resist composition for immersion exposure that can sufficiently satisfy general characteristics such as sensitivity and LWR, can reduce development defects during development, and is excellent in storage stability. Can do. Therefore, the resist composition for immersion exposure can be suitably used for a manufacturing process using an immersion exposure method in a semiconductor device in which further miniaturization of a pattern proceeds.

Claims (6)

[A] a polymer having a structural unit (I) containing a group represented by the following formula (i) and containing a fluorine atom ;
[B] an acid generator , and
[D] an acid diffusion controller ,
The structural unit (I) is represented by the following formula (1):
[D] The resist composition for immersion exposure , wherein the acid diffusion controller is a photodegradable acid diffusion controller .

(In formula (i), R ¹ is an alkali dissociable group represented by any one of the following formulas (iii) to (v). A is a group represented by —SO ₂ —O— *. * Indicates the binding site to R ¹ above.)

(In formula (iii), R ⁵ and R ⁶ are each independently a monovalent organic group having 1 to 20 carbon atoms, provided that R ⁵ and R ⁶ are bonded to each other, and (A ring structure may be formed with the carbon atom to which it is bonded.)

(In formula (iv), R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms, provided that R ⁷ and R ⁸ are bonded to each other, and (A ring structure may be formed together with the nitrogen atom bonded thereto.)

(In formula (v), R ⁹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms.)

(In Formula (1), R < ¹ > and A are synonymous with the said Formula (i). X is a single bond or a C1-C20 bivalent chain hydrocarbon group, provided that the above chain A part or all of hydrogen atoms of the hydrocarbon group may be substituted with a fluorine atom, R ² is a single bond, a divalent chain hydrocarbon group having 1 to 20 carbon atoms or 3 carbon atoms. A divalent alicyclic hydrocarbon group having ˜20, R ³ is an (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms, or an (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms; At least one group selected from the group consisting of —CO—, —COO—, —OCO—, —O—, —NR—, —CS—, —S—, —SO—, and —SO ₂ —; is a group combining. However, when n is 1, R ³ may be a single bond. in addition, the (n + 1) hydrogen with the valent hydrocarbon group Some or all of the child, may be substituted with a fluorine atom .E represents a single bond, an oxygen atom, a -CO-O-* or -CO-NH- *. * Is the above ^{R 3} R ⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, n is an integer of 1 to 3. When n is 2 or more, a plurality of R ¹ , A , X and R ² may be the same or different. [C] a polymer having a smaller fluorine atom content than the above [A] polymer,
The resist composition for immersion exposure according to claim 1 , wherein the [C] polymer has an acid dissociable group. [A] The resist composition for immersion exposure according to claim 1 or 2, wherein the polymer further has a structural unit (II) represented by the following formula (2) .

(In formula (2), R is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y is a group represented by the following formula (Y-1).)

(In formula (Y-1), R ^b1 , R ^b2 and R ^b3 are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ^b2 and R ^b3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. [C] The resist composition for immersion exposure according to claim 2 , wherein the polymer has the structural unit (II) . [A] The resist composition for immersion exposure according to any one of claims 1 to 4, wherein the polymer further has a structural unit (III) represented by the following formula (3) .

(In Formula (3), R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^L1 is a single bond or a divalent linking group. R ^Lc is 1 having a lactone structure. A monovalent organic group, a monovalent organic group having a sultone structure, or a monovalent organic group having a cyclic carbonate structure.) [C] The resist composition for immersion exposure according to claim 2 , wherein the polymer further comprises the structural unit (III) .