JP2013254084A - Photoresist composition, resist pattern formation method, polymer, compound and method of producing compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoresist composition superior in LWR performance, resolution, rectangularity of a cross-sectional shape, and focal depth.SOLUTION: A photoresist composition contains [A] a polymer having a structural unit represented by the following formula (1), and [B] an acid generator.

Description

  The present invention relates to a photoresist composition, a resist pattern forming method, a polymer, a compound, and a method for producing the compound.

  Chemically amplified photoresist compositions used for microfabrication by lithography generate acid in exposed areas by irradiation with far ultraviolet rays such as ArF excimer laser light, electromagnetic waves such as X-rays, and charged particle beams such as electron beams. The resist pattern is formed by causing a difference in dissolution rate in the developer between the exposed portion and the unexposed portion by a chemical reaction using this acid as a catalyst.

  Such a photoresist composition is required to improve lithography performance such as sensitivity and resolution as processing technology becomes finer. In response to this requirement, various structures of acid-dissociable groups possessed by the polymer contained in the photoresist composition have been studied. For example, those having a plurality of specific ring structures have been studied to improve resolution and the like. It is supposed to be possible (see JP 2011-43794 A).

  However, at present, when the miniaturization of the resist pattern has progressed to a level of a half pitch of 40 nm or less, the above photoresist composition is not only excellent in resolution but also LWR (Line Width Roughness) performance. In addition to these, the resist pattern must have excellent cross-sectional rectangularity, and in addition to these, it must be excellent in depth of focus (DOF), and a high-precision pattern can be formed with high yield. Yes. However, the above conventional photoresist composition cannot satisfy these performances.

JP 2011-43794 A

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a photoresist composition excellent in LWR performance, resolution, rectangularity in cross-sectional shape, and depth of focus.

（式（１）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、ヒドロキシ基若しくは炭素数１〜２０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに結合してそれらが結合する炭素原子と共に炭素数３〜１０の環構造を形成している。ａは、１〜６の整数である。但し、ａが２以上の場合、複数のＲ^２及びＲ^３はそれぞれ同一でも異なっていてもよい。Ｒ^４及びＲ^５は、それぞれ独立して、極性を有する１価の特定基（ａ）、水素原子又は炭素数１〜２０の１価の炭化水素基である。特定基（ａ）は、ヒドロキシ基、カルボキシ基、スルホ基、シアノ基、ハロゲン原子、ラクトン構造を有する基、環状カーボネート構造を有する基、スルトン構造を有する基、環状スルホン構造を有する基、ラクタム構造を有する基、スルタム構造を有する基、環状スルホンイミド構造を有する基、−ＣＯＯＲ^Ａ、−ＯＣＯＯＲ^Ｂ、−ＳＯ_２ＯＲ^Ｃ、−ＯＣＯＲ^ａ、−ＯＳＯ_２Ｒ^ｂ、−ＳＯ_２Ｒ^ｃ、−ＣＯＮＲ^αＲ^ｄ、−ＮＲ^βＣＯＲ^ｅ、−ＳＯ_２ＮＲ^γＲ^ｆ、−ＮＲ^δＳＯ_２Ｒ^ｇ及び−ＳＯ_２ＮＲ^εＳＯ_２Ｒ^ｈからなる群より選ばれる少なくとも１種を含む基である。Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃは、それぞれ独立して、非酸解離性の炭素数１〜２０の１価の炭化水素基である。Ｒ^ａ〜Ｒ^ｈ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。Ｒ^α〜Ｒ^εは、それぞれ独立して、水素原子又は炭素数１〜１０の１価の炭化水素基である。但し、Ｒ^４及びＲ^５のうちの少なくともいずれかは、特定基（ａ）である。） The invention made to solve the above problems is
[A] a polymer (hereinafter also referred to as “[A] polymer”) having a structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (I)”), and [B] acid A photoresist composition containing a generator.

(In Formula (1), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).)

The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film using the photoresist composition;
(2) a step of exposing the resist film; and (3) a step of developing the exposed resist film.

（式（１）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、ヒドロキシ基若しくは炭素数１〜２０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに結合してそれらが結合する炭素原子と共に炭素数３〜１０の環構造を形成している。ａは、１〜６の整数である。但し、ａが２以上の場合、複数のＲ^２及びＲ^３はそれぞれ同一でも異なっていてもよい。Ｒ^４及びＲ^５は、それぞれ独立して、極性を有する１価の特定基（ａ）、水素原子又は炭素数１〜２０の１価の炭化水素基である。特定基（ａ）は、ヒドロキシ基、カルボキシ基、スルホ基、シアノ基、ハロゲン原子、ラクトン構造を有する基、環状カーボネート構造を有する基、スルトン構造を有する基、環状スルホン構造を有する基、ラクタム構造を有する基、スルタム構造を有する基、環状スルホンイミド構造を有する基、−ＣＯＯＲ^Ａ、−ＯＣＯＯＲ^Ｂ、−ＳＯ_２ＯＲ^Ｃ、−ＯＣＯＲ^ａ、−ＯＳＯ_２Ｒ^ｂ、−ＳＯ_２Ｒ^ｃ、−ＣＯＮＲ^αＲ^ｄ、−ＮＲ^βＣＯＲ^ｅ、−ＳＯ_２ＮＲ^γＲ^ｆ、−ＮＲ^δＳＯ_２Ｒ^ｇ及び−ＳＯ_２ＮＲ^εＳＯ_２Ｒ^ｈからなる群より選ばれる少なくとも１種を含む基である。Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃは、それぞれ独立して、非酸解離性の炭素数１〜２０の１価の炭化水素基である。Ｒ^ａ〜Ｒ^ｈ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。Ｒ^α〜Ｒ^εは、それぞれ独立して、水素原子又は炭素数１〜１０の１価の炭化水素基である。但し、Ｒ^４及びＲ^５のうちの少なくともいずれかは、特定基（ａ）である。） The polymer of the present invention has a structural unit represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).)

（式（ｉ）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、ヒドロキシ基若しくは炭素数１〜２０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに結合してそれらが結合する炭素原子と共に炭素数３〜１０の環構造を形成している。ａは、１〜６の整数である。但し、ａが２以上の場合、複数のＲ^２及びＲ^３はそれぞれ同一でも異なっていてもよい。Ｒ^４及びＲ^５は、それぞれ独立して、極性を有する１価の特定基（ａ）、水素原子又は炭素数１〜２０の１価の炭化水素基である。特定基（ａ）は、ヒドロキシ基、カルボキシ基、スルホ基、シアノ基、ハロゲン原子、ラクトン構造を有する基、環状カーボネート構造を有する基、スルトン構造を有する基、環状スルホン構造を有する基、ラクタム構造を有する基、スルタム構造を有する基、環状スルホンイミド構造を有する基、−ＣＯＯＲ^Ａ、−ＯＣＯＯＲ^Ｂ、−ＳＯ_２ＯＲ^Ｃ、−ＯＣＯＲ^ａ、−ＯＳＯ_２Ｒ^ｂ、−ＳＯ_２Ｒ^ｃ、−ＣＯＮＲ^αＲ^ｄ、−ＮＲ^βＣＯＲ^ｅ、−ＳＯ_２ＮＲ^γＲ^ｆ、−ＮＲ^δＳＯ_２Ｒ^ｇ及び−ＳＯ_２ＮＲ^εＳＯ_２Ｒ^ｈからなる群より選ばれる少なくとも１種を含む基である。Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃは、それぞれ独立して、非酸解離性の炭素数１〜２０の１価の炭化水素基である。Ｒ^ａ〜Ｒ^ｈ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。Ｒ^α〜Ｒ^εは、それぞれ独立して、水素原子又は炭素数１〜１０の１価の炭化水素基である。但し、Ｒ^４及びＲ^５のうちの少なくともいずれかは、特定基（ａ）である。） The compound of the present invention is represented by the following formula (i).

(In formula (i), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).)

（式（ｉ−ａ）、式（ｉ−ｂ）及び式（ｉ）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、ヒドロキシ基若しくは炭素数１〜２０の１価の炭化水素基であるか、又はＲ^２及びＲ^３が互いに結合してそれらが結合する炭素原子と共に炭素数３〜１０の環構造を形成している。ａは、１〜６の整数である。但し、ａが２以上の場合、複数のＲ^２及びＲ^３はそれぞれ同一でも異なっていてもよい。Ｒ^４及びＲ^５は、それぞれ独立して、極性を有する１価の特定基（ａ）、水素原子又は炭素数１〜２０の１価の炭化水素基である。特定基（ａ）は、ヒドロキシ基、カルボキシ基、スルホ基、シアノ基、ハロゲン原子、ラクトン構造を有する基、環状カーボネート構造を有する基、スルトン構造を有する基、環状スルホン構造を有する基、ラクタム構造を有する基、スルタム構造を有する基、環状スルホンイミド構造を有する基、−ＣＯＯＲ^Ａ、−ＯＣＯＯＲ^Ｂ、−ＳＯ_２ＯＲ^Ｃ、−ＯＣＯＲ^ａ、−ＯＳＯ_２Ｒ^ｂ、−ＳＯ_２Ｒ^ｃ、−ＣＯＮＲ^αＲ^ｄ、−ＮＲ^βＣＯＲ^ｅ、−ＳＯ_２ＮＲ^γＲ^ｆ、−ＮＲ^δＳＯ_２Ｒ^ｇ及び−ＳＯ_２ＮＲ^εＳＯ_２Ｒ^ｈからなる群より選ばれる少なくとも１種を含む基である。Ｒ^Ａ、Ｒ^Ｂ及びＲ^Ｃは、それぞれ独立して、非酸解離性の炭素数１〜２０の１価の炭化水素基である。Ｒ^ａ〜Ｒ^ｈ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。Ｒ^α〜Ｒ^εは、それぞれ独立して、水素原子又は炭素数１〜１０の１価の炭化水素基である。但し、Ｒ^４及びＲ^５のうちの少なくともいずれかは、特定基（ａ）である。Ｒ’は、１価の炭化水素基である。Ｅは、ハロゲン原子である。） The method for producing a compound represented by the following formula (i) of the present invention is as follows:
A step of reacting a compound represented by the following formula (ia) with a compound represented by the following formula (ib).

(In Formula (ia), Formula (ib), and Formula (i), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom or a fluorine atom. , A hydroxy group or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded. A is an integer of 1 to 6. However, when a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently , A monovalent specific group having polarity (a), a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, the specific group (a) being a hydroxy group, a carboxy group, a sulfo group, a cyano group, A halogen atom, a group having a lactone structure, a group having a cyclic carbonate structure, Group having emission structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a , -OSO ₂ R ^b , -SO ₂ R ^c , -CONR ^α R ^d , -NR ^β COR ^e , -SO ₂ NR ^γ R ^f , -NR ^δ SO ₂ R ^g, and -SO ₂ NR ^ε SO ₂ R ^h Each of R ^A , R ^B and R ^C is independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{a to} R ^h are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon having 1 to 10 carbon atoms. of a hydrocarbon group. However, R ⁴及At least one of R ^5, a specific group (a) .R 'is a monovalent hydrocarbon radical .E is a halogen atom.)

  According to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern excellent in LWR, resolution and rectangularity can be formed while exhibiting a wide depth of focus. The polymer of the present invention can be suitably used as a polymer component of the photoresist composition. The compound of the present invention can be suitably used as a raw material monomer for the polymer. Therefore, the present invention can be suitably used for pattern formation such as semiconductor manufacturing, and the quality of fine patterns can be improved and the yield of products can be improved.

<Photoresist composition>
The photoresist composition contains a [A] polymer and a [B] acid generator. The photoresist composition may contain, as suitable components, [C] acid diffusion controller, [D] fluorine atom-containing polymer, [E] solvent, and [F] uneven distribution accelerator. Other optional components may be contained as long as the effect is not impaired. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). Since the [A] polymer has the structural unit (I), the photoresist composition is excellent in LWR performance, resolution, rectangularity in cross-sectional shape, and depth of focus. The reason why the photoresist composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, the structural unit (I) of the polymer [A] has a specific lactone ring that shares a carbon atom with the polymer chain as shown in the above formula (1), and additionally has the above polarity. It has a specific group (a). [A] The polymer has the above-mentioned specific lactone ring to increase its rigidity, and the polymer has the above-mentioned specific group (a) to increase its polarity. As a result, due to the synergistic effect of the rigidity and the polarity, the diffusion length of the acid generated from the [B] acid generator is appropriately shortened in the formed resist film. Therefore, the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus of the photoresist composition are improved.

  [A] The polymer is a structural unit (II) containing an acid dissociable group in addition to the structural unit (I), and a structural unit other than the structural unit (I), and includes a lactone structure, a cyclic carbonate structure, and a sultone It preferably has a structural unit (III) containing at least one structure selected from the group consisting of structures, and may have other structural units other than the structural units (I) to (III). Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the following formula (1).

In said formula (1), R < ¹ > is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R ² and R ³ are bonded to each other. A ring structure having 3 to 10 carbon atoms is formed together with the carbon atoms to be bonded. a is an integer of 1-6. However, when a is 2 or more, the plurality of R ² and R ³ may be the same or different. R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, a hydrogen atom, or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Specific group (a) is a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a lactam structure , A group having a sultam structure, a group having a cyclic sulfonimide structure, -COOR ^A , -OCOOR ^B , -SO ₂ OR ^C , -OCOR ^a , -OSO ₂ R ^b , -SO ₂ R ^c , -CONR ^alpha R ^d, is a group containing at least one _{^{-NR β COR e, -SO 2 NR}} γ R f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^{-SO 2 NR ε SO 2 R h}} . R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{a to} R ^h are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. However, at least one of R ⁴ and R ⁵ is the specific group (a).

R ¹ is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer compound giving the structural unit (I).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ² and R ³ include, for example,
Alkyl groups such as methyl, ethyl, propyl, butyl, and pentyl groups;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Alkynyl groups such as ethynyl group, propynyl group, butynyl group, pentynyl group;
Cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group;
A cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a norbornenyl group, a tricyclodecenyl group;
Aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl;
Examples include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

Examples of the ring structure having 3 to 10 carbon atoms formed together with the carbon atom to which R ² and R ³ are bonded to each other include:
Cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure;
Cycloalkene structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure;
And cycloalkadiene structures such as a cyclobutadiene structure and a cyclopentadiene structure.

  a is preferably an integer of 1 to 3, more preferably 1 or 2, and still more preferably 1.

R ² and R ³ are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

Examples of the group having a lactone structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms and a lactone structure having 4 to 20 ring members, and butyrolactone. -Yl group, butyrolactone-ylalkyl group, methylbutyrolactone-yl group, methylbutyrolactone-ylalkyl group, norbornanelactone-yl group, norbornanelactone-ylalkyl group and the like.

Examples of the group having a cyclic carbonate structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms having a cyclic carbonate structure having 4 to 20 ring members, and the like. Examples thereof include an ethylene carbonate-yl group, a propylene carbonate-yl group, a cyclohexene carbonate-yl group, an ethylene carbonate-yl alkyl group, a propylene carbonate-yl alkyl group, and a cyclohexene carbonate-yl alkyl group.

Examples of the group having a sultone structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms and a sultone structure having 4 to 20 ring members, and butyrosultone. -Yl group, norbornane sultone-yl group, butyrosulton-ylalkyl group, norbornane sultone-ylalkyl group and the like can be mentioned.

Examples of the group having a cyclic sulfone structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms and a cyclic sulfone structure having 4 to 20 ring members. , Sulfolane-yl group, norbornane sulfone-yl group, sulfolane-yl alkyl group, norbornane sulfone-yl alkyl group and the like.

Examples of the group having a lactam structure included in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms and a lactam structure having 4 to 20 ring members, and butyrolactam. -Yl group, valerolactam-yl group, caprolactam-yl group, butyrolactam-ylalkyl group, valerolactam-ylalkyl group, caprolactam-ylalkyl group and the like.

Examples of the group having a sultam structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms and a sultam structure having 4 to 20 ring members, and butyrosultam. -Yl group, valerosultam-yl group, caprosultam-yl group, norbornane sultam-yl group, butyrosultam-ylalkyl group, valerosultam-ylalkyl group, caprosultam-ylalkyl group, norbornanesultam-ylalkyl group, etc. .

Examples of the cyclic sulfonimide structure contained in the specific group (a) represented by R ⁴ and R ⁵ include a group having 4 to 30 carbon atoms having a cyclic sulfonimide structure having 4 to 20 ring members, and the like. Cycloalkyl-1,3-bis (sulfonyl) imido-yl group, perfluorocycloalkyl-1,3-bis (sulfonyl) imido-yl group, cycloalkyl-1,3-bis (sulfonyl) imido-ylalkyl group And perfluorocycloalkyl-1,3-bis (sulfonyl) imido-ylalkyl group.

R ^A , R ^B, and R ^C are each a non-acid dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms that replaces a hydrogen atom of —COOH, —OCOOH, and —SO ₂ OH, respectively. Since the above-mentioned R ^A , R ^B and R ^C are non-acid-dissociable groups, the change in polarity in the structural unit (I) is small even after exposure, so the polarity of the [A] polymer is adjusted more appropriately. As a result, the LWR performance and resolution of the photoresist composition are further improved.

Examples of the non-acid dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^A , R ^B and R ^C include, for example, a methyl group; an ethyl group, an n-propyl group, and an i-propyl group. Alkyl groups having primary or secondary carbon atoms such as cyclopentyl group, cyclohexyl group or the like; cycloalkyl groups having secondary carbon atoms such as cyclopentyl group or cyclohexyl group; aryl groups such as phenyl group or tolyl group; benzyl And an aralkyl group having a primary or secondary carbon atom such as a group or a phenethyl group at the binding site.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^{a to} R ^h are the same as those exemplified as the monovalent hydrocarbon group represented by R ² and R ³ . Groups and the like.

Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ^{α to} R ^ε include groups exemplified as the monovalent hydrocarbon group represented by R ² and R ³ , Examples include groups having 1 to 10 carbon atoms.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ⁴ and R ⁵ are the same groups as those exemplified as the monovalent hydrocarbon group represented by R ² and R ^3. Etc.

R ⁴ and R ⁵ include a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, and a cyclic sulfonimide It preferably contains a group having a structure or an alicyclic hydrocarbon group. In the photoresist composition, R ⁴ and R ⁵ of the polymer [A] contain a group having the specific cyclic structure, so that the rigidity thereof is increased, and as a result, the LWR performance and the resolution are further improved. To do.
Among these groups, a group having a lactone structure is preferable, a group having a butyrolactone structure is more preferable, a butyrolactone-yl group and a methylbutyrolactone-yl group are more preferable, and 1-methyl-γ-butyrolactone-1 is preferable. A -yl group is particularly preferred.

R ⁴ and R ⁵ preferably contain a hydroxy group. In the photoresist composition, when R ⁴ and R ⁵ of the [A] polymer contain a hydroxy group, the polarity thereof is increased, and as a result, the LWR performance and the resolution are further improved.
Among these groups, a hydroxycycloalkyl group and a hydroxyalkyl group are preferable among these groups, a hydroxyadamantyl group and a hydroxyethyl group are more preferable, and a 3-hydroxyadamantan-1-yl group is more preferable.

Moreover, as said R < ⁴ > and R < ⁵ >, a C1-C20 monovalent hydrocarbon group is also preferable, an alkyl group is more preferable, and a methyl group is further more preferable.

R ⁴ and R ⁵ preferably have no acid dissociable group. Since R ⁴ and R ⁵ do not have an acid-dissociable group, the change in polarity in the structural unit (I) is small even after exposure. Therefore, the polarity of the [A] polymer can be adjusted more appropriately. As a result, the LWR performance and resolution of the photoresist composition are further improved.

  The specific group (a) is preferably represented by the following formula (2). In the photoresist composition, when the specific group (a) is represented by the following formula (2), LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus are improved.

In the above formula (2), Y represents a chain hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, a group having a lactone structure having 4 to 10 ring members, and 4 ring members. A group having a cyclic carbonate structure of 10 to 10, a group having a sultone structure having 4 to 20 ring members, a group having a cyclic sulfone structure having 4 to 20 ring members, a group having a lactam structure having 4 to 10 ring members, and 4 ring members It is an (n + 1) -valent group obtained by combining at least one selected from the group consisting of a group having a -20 sultam structure and a group having a cyclic sulfonimide structure having 4 to 20 ring members, or a combination thereof. X _{^{is, -R p -OH, -R q -COOH}} , -R r -SO 3 H, -R s -CN, -R t -COOR A, -R u -OCOOR B and ^-R v _-SO 2 OR ^{C 1} , a halogen atom or a halogenated hydrocarbon group having 1 to 20 carbon atoms. R ^{p to} R ^v are each independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. R ^A , R ^B and R ^C have the same ^{meaning as} in the above formula (1). n is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, or a group having a cyclic sulfonimide structure Is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, and a sultam structure. When neither the group to have nor the group which has a cyclic sulfonimide structure is contained, it is an integer of 1-3. When n is 2 or more, the plurality of Xs may be the same or different.

Examples of the (n + 1) -valent chain hydrocarbon group having 1 to 20 carbon atoms represented by Y include, for example,
Alkanes such as methane, ethane, propane, butane, pentane, hexane;
And groups obtained by removing (n + 1) hydrogen atoms from alkenes such as ethene, propene, butene, pentene, and hexene.

Examples of the (n + 1) -valent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by Y include monocyclic cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane;
Polycyclic cycloalkanes such as norbornane, adamantane, tricyclodecane, tetracyclododecane;
Monocyclic cycloalkenes such as cyclopropene, cyclobutene, cyclopentene, cyclohexene;
And a group obtained by removing (n + 1) hydrogen atoms from polycyclic cycloalkene such as norbornene, tricyclodecene, tetracyclododecene, and the like.

A group having an (n + 1) -valent lactone structure having 4 to 10 ring members, a group having an (n + 1) -valent cyclic carbonate structure having 4 to 10 ring members, and (n + 1) having 4 to 20 ring members. A group having a valent sultone structure, a group having an (n + 1) -valent cyclic sulfone structure having 4 to 20 ring members, a group having an (n + 1) -valent lactam structure having 4 to 10 ring members, and a group having 4 to 20 ring members ( Examples of the group having an (n + 1) -valent sultam structure and the group having an (n + 1) -valent cyclic sulfonimide structure having 4 to 20 ring members include, for example, n from each monovalent group exemplified as R ⁴ and R ⁵ above. And a group in which a hydrogen atom is removed.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p to R ^v, for example, by removing one hydrogen atom from a monovalent hydrocarbon group exemplified as R ² and R ³ Groups and the like.

  Examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom is preferable.

As the monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms represented by X, a part or all of the hydrogen atoms of the monovalent hydrocarbon group represented by R ² and R ³ are halogenated. Examples include a group substituted with an atom, and examples thereof include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a perfluoroethyl group, and a perfluoropropyl group.

N is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, or a cyclic sulfonimide structure. When it has the group which has, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.
In addition, n is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, or a cyclic sulfonimide. When it does not contain the group which has a structure, 1 or 2 is preferable and 1 is more preferable.

R ⁴ and R ⁵ are preferably a group having a lactone structure, a group having a hydroxy group, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a butyrolactone structure, a hydroxycycloalkyl group, or a hydroxyalkyl group. An alkyl group is more preferable, a methylbutyrolactone-yl group, a hydroxyadamantyl group, a hydroxyethyl group, and a methyl group are more preferable, a 1-methyl-γ-butyrolactone-1-yl group, a 3-hydroxyadamantan-1-yl group, A methyl group is particularly preferred.

As a combination of R ⁴ and R ⁵ , R ⁴ is preferably the specific group (a), and R ⁵ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. In the photoresist composition, since the [A] polymer has a combination of the above specific R ⁴ and R ⁵ , the rigidity and polarity can be adjusted more appropriately, and as a result, the LWR performance, the solution The image quality, the rectangular shape of the cross-sectional shape, and the depth of focus can be further improved.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-12) (hereinafter also referred to as “structural units (I-1) to (I-12)”). Etc.

In the formulas (1-1) to (1-12), R ¹ has the same meaning as the formula (1).

  Among these, the structural units (I-1) to (I-3), (I-11) and (I-12) are preferable, and the structural units (I-1) to (I-3) are more preferable.

  As a content rate of structural unit (I), 0.5 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 1 mol%-50 mol% are more preferable, 2 More preferably, mol% to 35 mol% is preferable, and 3 mol% to 20 mol% is particularly preferable. By making the content rate of structural unit (I) into the said range, the LWR performance of the said photoresist composition, resolution, the rectangularity of a cross-sectional shape, and a focal depth can be improved. When the content ratio of the structural unit (I) is less than the lower limit, the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus may be deteriorated. When the content ratio of the structural unit (I) exceeds the above upper limit, the pattern forming property of the photoresist composition may be deteriorated.

  [A] As described later, the polymer [A] can be obtained by radical polymerization or the like with a monomer that gives the structural unit (I) and a monomer that gives another structural unit, if necessary. The method for synthesizing the compound giving the structural unit (I) is, for example, as follows.

In the above formula (ia), formula (ib), and formula (i), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R ² and R ³ are bonded to each other. A ring structure having 3 to 10 carbon atoms is formed together with the carbon atoms to be bonded. a is an integer of 1-6. However, when a is 2 or more, the plurality of R ² and R ³ may be the same or different. R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, a hydrogen atom, or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Specific group (a) is a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a lactam structure , A group having a sultam structure, a group having a cyclic sulfonimide structure, -COOR ^A , -OCOOR ^B , -SO ₂ OR ^C , -OCOR ^a , -OSO ₂ R ^b , -SO ₂ R ^c , -CONR ^alpha R ^d, is a group containing at least one _{^{-NR β COR e, -SO 2 NR}} γ R f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^{-SO 2 NR ε SO 2 R h}} . R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{a to} R ^h are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. However, at least one of R ⁴ and R ⁵ is the specific group (a). R ′ is a monovalent hydrocarbon group. E is a halogen atom.

  The carbonyl compound represented by the above formula (ia) and the halogenated acrylic acid ester represented by the above formula (ib) in the presence of zinc (preferably an activator such as chlorotrimethylsilane) In the presence of a compound such as tetrahydrofuran (THF), a compound represented by the compound (i) that gives the structural unit (I) is obtained.

  Examples of the halogen atom represented by E include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a bromine atom is preferable from the viewpoint of reaction yield.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group and dissociates by the action of an acid. In the photoresist composition, the [A] polymer has the structural unit (II), so that the sensitivity can be improved. As a result, the LWR performance, the resolution, the rectangularity of the cross-sectional shape, and the focal depth can be improved. Further improvement can be achieved.

  Examples of the structural unit (II) include a structural unit represented by the following formula (2).

In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ⁸ and R ⁹ are each independently an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms, or R ⁸ and R ⁹ are bonded to each other, A ring structure having 3 to 10 carbon atoms is formed together with the carbon atom to which is bonded.

R ⁶ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer giving the structural unit (II).

Examples of the alkyl group having 1 to 6 carbon atoms represented by R ^{7 to} R ⁹ include, for example, methyl group, ethyl group, n-propyl, i-propyl group, n-butyl group, i-butyl group, sec- A butyl group, a t-butyl group, etc. are mentioned. Among these, a methyl group, an ethyl group, and an i-propyl group are preferable.

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^{7 to} R ⁹ include monocyclic cycloalkyl groups such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group; Examples thereof include polycyclic cycloalkyl groups such as a norbornyl group and an adamantyl group. Among these, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are preferable.

Examples of the ring structure having 3 to 10 carbon atoms that may be formed by combining R ⁸ and R ⁹ with each other include, for example, a monocyclic cycloalkane structure such as a cyclopentane structure, a cyclohexane structure, and a cyclooctane structure; a norbornane structure , Polycyclic cycloalkane structures such as adamantane structures; monocyclic divalent aliphatic heterocyclic structures such as azacyclopentane structures and oxacyclopentane structures; polycyclic bivalent structures such as azanorbornane structures and oxanorbornane structures Examples thereof include an aliphatic heterocyclic structure. Among these, a monocyclic cycloalkane structure is preferable, a cyclopentane structure, a cyclohexane structure, and a cyclooctane structure are more preferable, and a cyclopentane structure is more preferable.

The structural unit (II), is preferably a structural unit having a cyclic structure having 3 to 10 carbon atoms attached ^{R 8} and ^{R 9} together, ^{R 8} and ^{R 9} are combined to a single 3 to 10 carbon atoms with each other A structural unit having a ring structure of a ring is more preferable, a structural unit derived from 1-alkyl-1-cycloalkyl (meth) acrylate is more preferable, and a structural unit derived from 1-alkyl-1-cyclopentyl (meth) acrylate is Particularly preferred is a structural unit derived from 1-methyl-1-cyclopentyl (meth) acrylate.

  Examples of the structural unit (II) include structural units represented by the following formulas (2-1) to (2-4) (hereinafter also referred to as “structural units (II-1) to (II-4)”). Etc.

In said formula (2-1)-(2-4), R < ⁶ >, R < ⁷ >, R < ⁸ > and R < ⁹ > are synonymous with said formula (2). n _p is an integer of 1 to 4.

As _np , 1, 2 or 4 is preferable and 1 is more preferable.

  Examples of the structural units (II-1) to (II-4) include structural units represented by the following formulas.

In said formula, R < ⁶ > is synonymous with the said Formula (2).

  As the structural unit (II), from the viewpoint of further improving the LWR performance, resolution, rectangularity of the cross-sectional shape and depth of focus of the photoresist composition, the structural unit (II-1) and the structural unit (II-3) ) Is preferable, a structural unit derived from 1-alkyl-1-cyclopentyl (meth) acrylate, a structural unit derived from 2- (adamantan-1-yl) alkane-2-yl (meth) acrylate is more preferable, More preferred are structural units derived from i-propyl-1-cyclopentyl (meth) acrylate and structural units derived from 2- (adamantan-1-yl) propan-2-yl (meth) acrylate.

  As a content rate of structural unit (II), 10 mol%-90 mol% are preferable, 25 mol%-80 mol% are more preferable, 40 mol%-70 mol% are more preferable. By making the content rate of structural unit (II) into the said range, the LWR performance of the said photoresist composition, resolution, the rectangularity of a cross-sectional shape, and a focal depth can be improved. When the content ratio of the structural unit (II) is less than the lower limit, the pattern forming property of the photoresist composition may be deteriorated. When the content ratio of the structural unit (II) exceeds the above upper limit, the adhesion of the formed resist pattern to the substrate may be lowered.

[Structural unit (III)]
The structural unit (III) is a structural unit other than the structural unit (I) and includes at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. It is considered that the solubility of the polymer [A] polymer can be appropriately adjusted by having the structural unit (III). Moreover, the adhesiveness to the board | substrate etc. of the resist pattern formed from the said photoresist composition can be improved. As a result, the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus of the photoresist composition can be improved. Here, the lactone structure refers to a structure having one ring (lactone ring) including a group represented by —O—C (O) —. The cyclic carbonate structure refers to a structure having one ring (cyclic carbonate ring) including a group represented by —O—C (O) —O—. The sultone structure refers to a structure having one ring (sultone ring) including a group represented by —O—S (O) ₂ —.

  Examples of the structural unit (III) include a structural unit represented by the following formula (3).

In the above formula (3), R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹¹ is a single bond or a divalent linking group. R ¹² is a monovalent group containing a lactone structure, a monovalent group containing a cyclic carbonate structure, or a monovalent group containing a sultone structure.

R ¹⁰ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (III).

Examples of the divalent linking group represented by R ¹¹ include, for example, a divalent linear or branched hydrocarbon group having 1 to 20 carbon atoms, one or more of these hydrocarbon groups, and —CO—, And groups composed of at least one group selected from the group consisting of —O—, —NH—, and —S—.

Examples of the monovalent group containing a lactone structure represented by R ¹² , the monovalent group containing a cyclic carbonate structure, and the monovalent group containing a sultone structure include the following formulas (g-1) to (g- 11) etc. are mentioned.

In the above formulas (g-1) to (g-4), R ^L1 is an oxygen atom or a methylene group. R ^L2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _L1 is 0 or 1. n _L2 is an integer of 0 to 3.
The formula (g-7) and (g-8) _{in, n C1} represents an integer of 0 to 2. n _{C2 to} n _C5 are each independently an integer of 0 to 2.
In the above formulas (g-8) to (g-11), R ^S1 is an oxygen atom or a methylene group. R ^S2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _S1 is 0 or 1. n _S2 is an integer of 0 to 3.
In the above formulas (g-1) to (g-11), * represents a site that binds to R ⁴ in the above formula (3).
Part or all of the hydrogen atoms of the groups represented by the above formulas (g-1) to (g-11) may be substituted.

Among these, R ¹² is (g-1), (g-3), (g) from the viewpoint of improving the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus of the photoresist composition. The groups represented by g-7) and (g-9) are preferred, the groups represented by (g-1) and (g-7) are more preferred, and the group represented by (g-1) is further preferable.
As said R ^<L1> and R ^<S1> , a methylene group is preferable. As R ^L2 and R ^S2 , a hydrogen atom is preferable. As said _nL1 and _nS1 , 0 is preferable. As said _nL2 and _nS2 , 1 or 2 is preferable and 1 is more preferable.
The group that replaces the hydrogen atom of the norbornane ring of the groups represented by (g-1) and (g-7) is preferably a cyano group, a trifluoromethyl group, or a methoxycarbonyl group, and more preferably a cyano group. .

  Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^{10 ′} is a hydrogen atom or a methyl group.

  As a monomer which gives structural unit (III), the monomer etc. which are represented by a following formula (3-m) are mentioned, for example.

In said formula (3-m), R < ¹⁰ >, R < ¹¹ > and R < ¹² > are synonymous with the said Formula (3).

Examples of R ¹⁰ , R ¹¹ and R ¹² in the above formula (3-m) include the same groups as those exemplified as the respective groups in the above formula (3).

  As a content rate of structural unit (III), 20 mol%-80 mol% are preferable, 30 mol%-70 mol% are more preferable, and 35 mol%-65 mol% are more preferable. By making the content rate of structural unit (III) into the said range, the LWR performance of the said photoresist composition, resolution, the rectangularity of a cross-sectional shape, and a focal depth can be improved more. In addition, the adhesion of the formed resist pattern to the substrate or the like can be improved. When the content ratio of the structural unit (III) is less than the above lower limit, the adhesion of the formed resist pattern to the substrate may be lowered. If the content ratio of the structural unit (III) exceeds the above upper limit, the pattern forming property of the photoresist composition may be deteriorated.

[Other structural units]
[A] The polymer may have, for example, a structural unit (IV) as another structural unit other than the structural units (I) to (III).

[Structural unit (IV)]
The structural unit (IV) is a structural unit other than the structural unit (I) and includes a polar group. [A] Since the polymer further has the structural unit (IV), the solubility of the [A] polymer can be appropriately adjusted, so that the dissolution contrast can be improved. As a result, the photoresist composition LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus can be improved.

  Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a carbonyl group, a nitro group, and a sulfonamide group. Among these, a hydroxy group, a carboxy group, and a carbonyl group are preferable, and a hydroxy group is more preferable.

  Examples of the structural unit (IV) include a structural unit represented by the following formula.

In the above formula, R ¹³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  Among these, a structural unit containing a hydroxy group is preferable, a structural unit having a hydroxy group and an adamantane skeleton is more preferable, and a structural unit derived from 3-hydroxy-1-adamantyl (meth) acrylate is more preferable.

  As a content rate of structural unit (IV), 0 mol%-30 mol% are preferable, 0 mol%-25 mol% are more preferable, 5 mol%-25 mol% are further more preferable. By making the content rate of structural unit (IV) into the said range, the LWR performance of the said photoresist composition, resolution, the rectangularity of a cross-sectional shape, and a focal depth can be improved more.

  [A] The polymer may have, for example, a structural unit containing a non-acid dissociable alicyclic hydrocarbon group in addition to the structural unit (IV) as the other structural unit. [A] As a content rate of the other structural unit in a polymer, 20 mol% or less is preferable and 10 mol% or less is more preferable.

<[A] Polymer Synthesis Method>
[A] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable polymerization reaction solvent using a polymerization initiator such as a radical polymerization initiator. For example, a method of dropping a solution containing a monomer and a radical polymerization initiator into a polymerization reaction solvent or a solution containing a monomer to cause a polymerization reaction, a solution containing the monomer, and a radical polymerization initiator A solution containing a polymerization reaction solvent or a monomer-containing solution by dropping each of the contained solutions separately, a plurality of types of solutions containing each monomer, and a solution containing a radical polymerization initiator It is preferable to synthesize | combine by methods, such as the method of dripping into the solution containing a polymerization reaction solvent or a monomer, and making it superpose | polymerize separately.

Examples of the polymerization reaction solvent include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These polymerization reaction solvents may be used alone or in combination of two or more.

  Although the reaction temperature in the said polymerization should just be suitably determined according to the kind of radical initiator, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropylene). Pionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylpropionitrile), and the like. These radical polymerization initiators 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 completion of the polymerization reaction, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols, alkanes and the like can be used singly 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] As a weight average molecular weight (Mw) by the gel permeation chromatography (GPC) of a polymer, 1,000-100,000 are preferable, 1,000-30,000 are more preferable, 2,000-20 Is more preferable, and 3,000 to 10,000 is particularly preferable. [A] By making Mw of a polymer into the said range, the LWR performance of the said photoresist composition, resolution, the rectangularity of a cross-sectional shape, and a focal depth can be improved more.

  [A] The ratio (Mw / Mn) of Mw and number average molecular weight (Mn) of the polymer is usually 1 to 5, preferably 1 to 3, more preferably 1 to 2, and 1 to 1.7. Is more preferable. By setting Mw / Mn within the above range, the LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus of the photoresist composition can be further improved.

  In this specification, Mw and Mn are GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL, manufactured by Tosoh), flow rate 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1. A value measured by GPC using a monodisperse polystyrene as a standard using a differential refractometer as a detector under the analysis conditions of 0% by mass, sample injection amount: 100 μL, column temperature: 40 ° C.

  [A] The low molecular weight content in the polymer (referring to the proportion (mass%) of the molecular weight of 1,000 or less) is preferably 5 mass% or less, more preferably 1 mass% or less, and 0.5 mass. % Or less is more preferable, and 0.2% by mass or less is particularly preferable. [A] By setting the low molecular weight content in the polymer within the above range, lithography properties such as LWR performance of the photoresist composition can be improved.

  In addition, the low molecular weight content (mass%) in the [A] polymer is Intersil ODS-25 μm (4.6 mmφ × 250 mm) (manufactured by GL Sciences) as a column by high performance liquid chromatography (HPLC). Using a differential refractometer as a detector under the analysis conditions of flow rate: 1.0 mL / min, elution solvent: acrylonitrile / 0.1% by mass phosphoric acid, sample concentration: 1.0% by mass, sample injection amount: 100 μL The measured value.

<[B] Acid generator>
[B] The acid generator is a compound that generates an acid upon irradiation with exposure light. The acid-dissociable group in the [A] polymer is dissociated by the action of the acid to generate a polar group such as a carboxy group, and as a result, the solubility of the [A] polymer in the developer changes. [B] The acid generator may be contained in the form of a compound as described later (hereinafter also referred to as “[B] acid generator” as appropriate), or in a form incorporated as part of a polymer. Both forms are acceptable.

  [B] Examples of the acid generator include onium salt compounds, N-sulfonylimide compounds, halogen-containing compounds, diazoketone compounds, and the like.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, and triphenylsulfonium 2-bicyclo [2.2. 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, tri Phenylsulfonium adamantane-1-yloxycarbonyldifluoromethanesulfonate, triphenylsulfonium 2- (adamantan-1-yl) -1,1-difluoroethane-1-sulfonate, triphenylsulfonium 6- (adama) Til-1-ylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate 4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfo Nato, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methyl Sulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate Etc.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene. Nimononafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) ) Tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalene- -Yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n- Butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octane Sulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, etc. Is mentioned.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, and bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate. Bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2 -Bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate and the like.

  Of these, onium salts are preferred, sulfonium salts and tetrahydrothiophenium salts are more preferred, sulfonium salts are more preferred, triphenylsulfonium salts are particularly preferred, and triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy). -1,1,3,3,3-pentafluoropropane-1-sulfonate is more particularly preferred.

  [B] The acid generator may be used alone or in combination of two or more. [B] The content when the acid generator is a [B] acid generator is as follows. From the viewpoint of ensuring the sensitivity and developability of the above photoresist composition as a resist, On the other hand, it is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, further preferably 1 part by mass or more and 15 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less. Is particularly preferred. [B] If the content of the acid generator is less than 0.1 parts by mass, the sensitivity tends to be insufficient. On the other hand, if it exceeds 30 parts by mass, the transparency to the exposure light decreases, and a desired resist pattern is formed. It may be difficult to obtain.

<[C] Acid diffusion controller>
[C] The acid diffusion controller is a component that controls the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film and suppresses an undesirable chemical reaction in the unexposed area. When the photoresist composition contains a [C] acid diffusion controller, the resolution of the resulting photoresist composition is improved, the storage stability is improved, and further, from the exposure to the development process. A change in the line width of the resist pattern due to a change in time can be suppressed, and a photoresist composition excellent in process stability can be obtained. In addition, as the inclusion form of the [C] acid diffusion controller, in the form of a free compound (hereinafter also referred to as “[C] acid diffusion controller” as appropriate), or in a form incorporated as part of the polymer, Both of these forms may be used.

  [C] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines such as 2,6-diisopropylaniline or derivatives thereof; ethylenediamine, N, N , N ′, N′-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) Propane, 2- (4-aminophenyl) -2- (4- Droxyphenyl) propane, 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, Bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′— Examples include tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine, and triethanolamine.

  Examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as t-butyl-4-hydroxy-1-piperidinecarboxylate, and t-amyl-4-hydroxy-1-piperidinecarboxylate. Nt-amyloxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methyl Examples include pyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea and the like. Is mentioned.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 4-hydroxy-N-amyloxycarbonylpiperidine, piperidineethanol, 3-piperidino- 1,2-propanediol; morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, N- (2-cyclohexylcarbonyloxyethyl) morpholine, 3- (N-morpholino) -1, Morpholines such as 2-propanediol; 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane and the like.

  Among these, amine compounds and amide group-containing compounds are preferable, substituted alkylanilines and Nt-amyloxycarbonyl group-containing compounds are more preferable, t-amyl-4-hydroxy-1-piperidinecarboxylate, 2,6 -Diisopropylaniline is more preferred.

  Moreover, the photodisintegration base which generate | occur | produces a weak acid by exposure can also be used as a [C] acid diffusion control agent. The photodegradable base exhibits an acid capturing function by an anion in an unexposed area and functions as a quencher, and captures an acid diffused from the exposed area. On the other hand, in the exposed area, an acid is generated and the anion disappears, so that the acid capturing function is lost. That is, since it functions as a quencher only in the unexposed area, the contrast of the dissociation reaction of the acid dissociable group is improved, and as a result, the lithography performance such as the resolution of the photoresist composition can be further improved. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (C1) and an iodonium salt compound represented by the following formula (C2).

In the above formula (C1) and formula (C2), R ^{14 to} R ¹⁸ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, a halogen atom, or —SO ₂ —R ⁱ . R ⁱ is an alkyl group, a cycloalkyl group, an alkoxy group or an aryl group. Z ^- and ^G - ^{is, OH -, R j -COO -} , R k -SO 2 -N - -R j, R j -SO 3 - is an anion represented by or the following formula (C3). R ^j is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group, cycloalkyl group, aryl group and aralkyl group may be substituted. R ^k is a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and cycloalkyl group may be substituted with fluorine atoms. However, when Z ⁻ is R ^j —SO ₃ ^— , a fluorine atom is not bonded to a carbon atom to which SO ₃ ^— is bonded.

In the formula (C3), R ^19, a part or all of the hydrogen atoms linear or branched alkyl group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, or carbon atoms from 1 to 12 These are linear or branched alkoxy groups. u is an integer of 0-2.

The ^R 14 ^{to R 18} in the formula (C1) and (C2), hydrogen atom, _-SO 2 -R ⁱ are preferred. In addition, R ⁱ is preferably a cycloalkyl group, and more preferably a cyclohexyl group.

Examples of the alkyl group represented by R ^j include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, an i-butyl group, a t-butyl group, and the like, and one of hydrogen atoms of these groups. Examples include groups in which part or all are substituted.

Examples of the cycloalkyl group represented by R ^j include, for example, a cyclopentyl group, a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group, an adamantyl group, etc., and a part of hydrogen atoms of these groups or Examples include groups in which all are substituted.

Examples of the aryl group represented by R ^j include a phenyl group, a naphthyl group, an anthranyl group, and the like, and a group in which some or all of the hydrogen atoms of these groups are substituted.

Examples of the aralkyl group represented by R ^j include a benzyl group, a phenylethyl group, a phenylpropyl group, and a group in which some or all of the hydrogen atoms of these groups are substituted.

  As a substituent which the said alkyl group, a cycloalkyl group, an aryl group, and an alkaryl group have, a hydroxyl group, a halogen atom, an alkoxy group, a lactone group, an alkylcarbonyl group etc. are mentioned, for example.

Examples of the alkyl group represented by R ^k include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the cycloalkyl group represented by R ^k include a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

  Examples of the photodegradable base include compounds represented by the following formulas.

  Among these, triphenylsulfonium salicylate and triphenylsulfonium 10-camphor sulfonate are preferable, and triphenylsulfonium 10-camphor sulfonate is more preferable.

  [C] The content of the acid diffusion controller is preferably 10 parts by mass or less with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. 0.1 mass part-7 mass parts are more preferable, and 0.3 mass part-5 mass parts are still more preferable. [C] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity of the resulting photoresist composition may be lowered. [C] The acid diffusion inhibitors may be used alone or in combination of two or more.

<[D] Fluorine atom-containing polymer>
It is preferable that the said photoresist composition contains a [D] fluorine atom containing polymer. The photoresist composition contains a [D] fluorine atom-containing polymer, so that when the resist film is formed, the distribution of the resist film surface layer depends on the oil-repellent characteristics of the [D] fluorine atom-containing polymer. Therefore, at the time of immersion exposure, elution to an immersion medium such as a [B] acid generator or a [C] acid diffusion controller described later in the resist film can be suppressed. In addition, since the photoresist composition contains a [D] fluorine atom-containing polymer, the receding contact angle of the resist film surface to be formed is increased, so that immersion exposure can be suitably performed and high-speed scanning is possible. become. In addition, as a [D] fluorine atom containing polymer, the polymer applicable to a [A] polymer shall be remove | excluded.

[D] The fluorine atom content of the fluorine atom-containing polymer is preferably higher than the fluorine atom content of the [A] polymer. [D] Since the fluorine atom-containing polymer has a higher fluorine atom content than the [A] polymer, it can be effectively unevenly distributed in the surface layer of the resist film on which the [D] fluorine atom-containing polymer is formed. As a result, the above-described effects at the time of immersion exposure can be further exhibited. [D] The fluorine atom content of the fluorine atom-containing polymer is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more. In addition, the fluorine atom content rate (mass%) of a polymer can obtain | require the structure of a polymer by < ¹³ > C-NMR, and can calculate it from the result.

  [D] The fluorine atom-containing polymer can be formed by polymerizing one or more monomers usually containing a fluorine atom in the structure.

  [D] The fluorine atom-containing polymer preferably has the following structural unit (FI) as a structural unit containing a fluorine atom in the structure. [D] The fluorine atom-containing polymer may have a structural unit other than the structural unit containing a fluorine atom in the structure. [D] The fluorine atom-containing compound may have one or more of these structural units.

[Structural unit (FI)]
The structural unit (FI) is a structural unit represented by the following formula (D1).

In the formula ^{(D1), R 20} represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a single bond or a divalent linking group. R ²¹ is an alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative group thereof.

  Examples of the divalent linking group represented by A include alkanediyl groups such as oxygen atom, sulfur atom, carbonyloxy group, oxycarbonyl group, amide group, sulfonylimide group, urethane group, and methanediyl group, and cyclopentane. A divalent alicyclic hydrocarbon group such as a diyl group, a divalent aromatic hydrocarbon group such as a benzenediyl group or a naphthalenediyl group, a divalent group containing a lactone structure such as a norbornanelactone diyl group, or the like And a combination of one or more of the above.

Examples of the alkyl group having 1 to 6 carbon atoms having at least one fluorine atom represented by R ²¹ include a fluoromethyl group, a difluoromethyl group, a perfluoromethyl group, a difluoroethyl group, a trifluoroethyl group, Examples include perfluoroethyl group, trifluoro-n-propyl group, pentafluoro-n-propyl group, hexafluoro-i-propyl group, difluoro-sec-butyl group, trifluoro-sec-butyl group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms and having at least one fluorine atom represented by R ²¹ include a fluorocyclopropyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, and a difluoro Examples include a cyclopentyl group, a tetrafluorocyclopentyl group, a perfluorocyclopentyl group, a difluorocyclohexyl group, a perfluorocyclohexyl group, and the like.

Examples of the derivative group for the alkyl group or monovalent alicyclic hydrocarbon group represented by R ²¹ include alkali dissociation of the hydrogen atom or fluorine atom of the alkyl group or monovalent alicyclic hydrocarbon group. And a group substituted with a group containing a functional group. The “alkali dissociable group” is a group that replaces a hydrogen atom of a polar group such as a hydroxy group or a carboxy group, for example, in the presence of an alkali (for example, 2.38 mass% tetramethylammonium hydroxy at 23 ° C. Group that dissociates in aqueous solution). Examples of the group containing an alkali dissociable group include -COOR '(R' is an alkyl group having 1 to 6 carbon atoms).

  Preferred monomers that give the structural unit (FI) include trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, and perfluoroethyl (meth) acrylic. Acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester , Perfluoro t-butyl (meth) acrylate, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylate, 1- (2,2,3,3, 4,4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) ) Acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6 , 6-octafluorohexyl) (meth) acrylic acid ester, 2,2,2-trifluoroethoxycarbonylmethyl (meth) acrylic acid ester, 1-ethoxycarbonyl-1,1-difluoro-2-butyl (meth) acrylic Acid ester, 2,2,2-trifluoroethoxycarbonylnorbornane lactonyl (meth) acrylic acid ester, 2- (2,2,2-trifluoroethoxycarbonylmethyloxy) -6 Vinyl naphthalene.

  As a content rate of a structural unit (FI), 5 mol% or more is preferable with respect to all the structural units which comprise a [D] fluorine atom containing polymer, 10 mol% or more is more preferable, 20 mol% or more Is more preferable, and 30 mol% or more is particularly preferable. If the content of the structural unit (FI) is less than 5 mol%, the receding contact angle may be less than 70 degrees, and elution of the acid generator from the resist film cannot be suppressed. May occur. [D] The fluorine atom-containing polymer may have only one type of structural unit (FI), or may have two or more types.

[Other structural units]
[D] The fluorine atom-containing polymer has a structure having an acid-dissociable group as another structural unit in addition to the above-described structural unit containing a fluorine atom, for example, for controlling the dissolution rate in a developer. A structural unit containing at least one structure selected from the group consisting of a unit, a lactone structure, a cyclic carbonate structure and a sultone structure, a structural unit containing a polar group such as a hydroxyl group and a carboxy group, a structural unit containing an alicyclic group, and a substrate In order to suppress light scattering due to reflection from the light, one or more structural units derived from an aromatic compound can be contained.

Examples of the structural unit having an acid dissociable group include structural units similar to the structural unit (II) of the [A] polymer.
Examples of the structural unit including at least one structure selected from the group consisting of the lactone structure, the cyclic carbonate structure, and the sultone structure include structural units similar to the structural unit (III) of the [A] polymer. .
As a structural unit containing the said polar group, the structural unit etc. similar to the structural unit (IV) of a [A] polymer are mentioned, for example.

  As a structural unit containing the said alicyclic group, the structural unit etc. which are represented by a following formula (D2) are mentioned, for example.

In said formula (D2), R < ²² > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ²³ is a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ²³ include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. 2] Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing one hydrogen atom from an alicyclic hydrocarbon such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane. Some or all of the hydrogen atoms possessed by the monovalent alicyclic hydrocarbon group are methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1- A linear or branched alkyl group having 1 to 4 carbon atoms, such as a methylpropyl group or a t-butyl group, a cycloalkyl group having 3 to 10 carbon atoms; a hydroxy group, a cyano group, or a hydroxyalkyl having 1 to 10 carbon atoms Group and a carboxy group may be substituted. Further, two hydrogen atoms bonded to the same carbon atom may be substituted with one oxygen atom to form a keto group.

Preferred monomers that give structural units containing the alicyclic group include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2. .2] Oct-2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.02,6] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.13. , 6.0 ^2,7 ] dodeca-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3 .3.1.1 ^3,7 ] dec-2-yl ester.

  Preferred monomers that give structural units derived from the aromatic compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, 2-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl-3-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl- 4-hydroxystyrene, 3,4-dihydroxystyrene, 2 4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (2-ethyl-2-propoxy) -Α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, benzyl (meth) acrylate, acenaphthylene, 5-hydroxyacena Butylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 1-anthryl (Meth) acrylate, 2-anthryl (meth) acrylate, 9-anthryl (meta ) Acrylate, 9-anthrylmethyl (meth) acrylate, 1-vinylpyrene.

  As a content rate of said other structural unit, it is 80 mol% or less normally, and 75 mol% or less is preferable.

  [D] The content of the fluorine atom-containing polymer is preferably 0.1 part by mass to 30 parts by mass, and more preferably 0.5 part by mass to 20 parts by mass with respect to 100 parts by mass of the polymer [A]. 1 mass part-10 mass parts are further more preferable.

<[D] Method for Synthesizing Fluorine Atom-Containing Polymer>
[D] The fluorine atom-containing polymer can be synthesized, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator. In addition, as a radical polymerization initiator, a polymerization reaction solvent, etc. used for the synthesis of [D] fluorine atom-containing polymer, the same as those exemplified in the method for synthesizing [A] polymer may be mentioned.

  As reaction temperature in the said superposition | polymerization, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  [D] The polystyrene equivalent weight average molecular weight (Mw) of the fluorine atom-containing polymer by GPC method is preferably 1,000 to 50,000, more preferably 3,000 to 30,000, and 5,000 to 20,000. 000 is more preferable. [D] When Mw of the fluorine atom-containing polymer is less than the lower limit, the formed resist film surface may not be able to obtain a sufficient advancing contact angle. On the other hand, when Mw exceeds the above upper limit, the developability of the resulting photoresist composition tends to decrease.

  [D] The Mw / Mn ratio of the fluorine atom-containing polymer is usually 1 to 3, preferably 1 to 2.5, and more preferably 1 to 2.

<[E] solvent>
The photoresist composition usually contains an [E] solvent. [E] Solvent is at least [A] polymer, [B] acid generator, [C] acid diffusion controller contained as needed, [D] fluorine atom-containing polymer, and other optional components described later If it can melt | dissolve or disperse | distribute, it will not specifically limit. [E] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

As an ether solvent, for example,
Dialiphatic ether solvents such as diethyl ether, dipropyl ether, dibutyl ether;
Aromatic ring ether solvents such as anisole and diphenyl ether;
Examples thereof include cyclic ether solvents such as tetrahydrofuran and dioxane.

Examples of ketone solvents include:
Acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-amyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone Chain ketone solvents such as trimethylnonanone and acetophenone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
And diketone solvents such as 2,4-pentanedione and acetonylacetone.

Examples of the amide solvent include
Chain amide solvents such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide;
Examples thereof include cyclic amide solvents such as N-methylpyrrolidone and N, N′-dimethylimidazolidinone.

Examples of ester solvents include:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n propionate -Butyl, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate, etc. Carboxylate solvent;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl acetate Carboxylic acid ester solvents of polyhydric alcohol partial ethers such as ether, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Lactone solvents such as γ-butyrolactone and γ-valerolactone;
Examples thereof include carbonate solvents such as diethyl carbonate and propylene carbonate.

Examples of the hydrocarbon solvent include
Aliphatic carbonization such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, methylcyclohexane A hydrogen-based solvent;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents and the like.

  Among these, ester solvents and ketone solvents are preferable, carboxylic acid ester solvents of polyhydric alcohol partial ethers, lactone solvents, and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate, γ-butyrolactone, and cyclohexanone are more preferable. Further preferred. [E] A solvent can be used individually by 1 type or in mixture of 2 or more types.

<[F] Localization promoter>
The [F] uneven distribution accelerator has the effect of segregating the [D] fluorine atom-containing polymer more efficiently on the resist film surface. By adding this uneven distribution promoter to the photoresist composition, the amount of the [D] fluorine atom-containing polymer added can be reduced as compared with the conventional case. Therefore, it is possible to further suppress the elution of components from the resist film to the immersion liquid without damaging the basic resist characteristics such as LWR, development defects, and pattern collapse resistance, and to perform immersion exposure at a higher speed by high-speed scanning. As a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. 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 at 1 atm of 100 ° C. or more. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

  Specific examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like.

  Specific examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

  Specific examples of the nitrile compound include succinonitrile. Specific examples of the polyhydric alcohol include glycerin and the like.

  As content of the said uneven distribution promoter in the said photoresist composition, 10 mass parts-500 mass parts are preferable with respect to 100 mass parts of total mass of a polymer, and 30 mass parts-300 mass parts are more preferable. As said uneven distribution promoter, only 1 type may be contained and 2 or more types may be contained.

<Other optional components>
The photoresist composition can contain a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like as other components in addition to the components [A] to [F]. In addition, the said photoresist composition may contain another arbitrary component individually by 1 type or in mixture of 2 or more types, respectively.

[Surfactant]
The surfactant has an effect of improving the coating property, striation, developability, and the like of the photoresist composition. 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 diacrylate. Nonionic surfactants such as stearate, commercially available products such as KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFac F171, F173 (above, manufactured by Dainippon Ink & Chemicals), Fluorad FC430, FC431 ( As above, manufactured by Sumitomo 3M, Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Manufactured) and the like.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has an effect of improving the dry etching resistance, pattern shape, adhesion to the substrate, and the like of the photoresist composition.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like.

[Sensitizer]
The sensitizer exhibits the effect of increasing the amount of acid generated from the [B] acid generator, and has the effect of improving the “apparent sensitivity” of the photoresist composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like.

<Method for preparing photoresist composition>
The photoresist composition includes, for example, [A] a polymer, [B] an acid generator, [C] an acid diffusion controller, [D] a fluorine atom-containing polymer, and others in a [E] solvent. Can be prepared by mixing the arbitrary components in a predetermined ratio. The prepared photoresist composition is preferably filtered and used, for example, with a filter having a pore diameter of 20 nm. As solid content concentration of the said photoresist composition, 0.1 mass%-50 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 1 mass%-15 mass% are further more preferable.

<Resist pattern formation method>
The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film using the photoresist composition;
(2) a step of exposing the resist film; and (3) a step of developing the exposed resist film.
According to the resist pattern forming method, since the above-described photoresist composition of the present invention is used, a resist pattern having a high LDO with a small LWR, excellent cross-sectional rectangularity, and high resolution can be formed while exhibiting a wide depth of focus. can do. Hereinafter, each step will be described.

[(1) Process]
In this step, a resist film is formed using the photoresist composition. As the substrate on which the resist film is formed, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate.

  Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. In addition, as a film thickness of the resist film formed, it is 10 nm-1,000 nm normally, and 10 nm-500 nm are preferable.

  After apply | coating the said photoresist composition, you may volatilize the solvent in a coating film by prebaking (PB) as needed. The PB temperature is appropriately selected depending on the composition of the photoresist composition, but is usually 30 ° C to 200 ° C, preferably 50 ° C to 150 ° C. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

  In order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be provided on the resist layer. Furthermore, in order to prevent the acid generator and the like from flowing out of the resist layer, an immersion protective film disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384 can be provided on the resist layer. These techniques can be used in combination.

[(2) Process]
In this step, the photoresist film formed in the step (1) is exposed. For example, an isotrench pattern can be formed by performing reduced projection exposure or the like on a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more with a desired pattern and a mask pattern. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, a first reduced projection exposure is performed on a desired area via a line and space pattern mask, and then the second is so that the line intersects the exposed portion where the first exposure has been performed. Reduced projection exposure is performed. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area. Examples of the immersion liquid used for exposure include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist layer on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  The electromagnetic wave or charged particle beam used for the exposure is appropriately selected according to the type of the [B] acid generator. For example, the electromagnetic wave includes ultraviolet rays, far ultraviolet rays, visible rays, X rays, γ rays, and the like. Examples of the charged particle beam include an electron beam and an α ray. Among these, electromagnetic waves are preferable, far ultraviolet rays are more preferable, ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are further preferable, and ArF excimer laser is particularly preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the photoresist composition and the type of additive. In the pattern forming method of the present invention, the exposure process may be performed a plurality of times, and the plurality of exposures may be performed using the same light source or different light sources, but ArF excimer laser light is used for the first exposure. It is preferable to use it.

  In addition, post exposure baking (PEB) is preferably performed after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the photoresist composition can proceed smoothly. As PEB temperature, it is 30 to 200 degreeC normally, and 50 to 170 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[(3) Process]
In this step, the resist film exposed in the step (2) is developed. Thereby, a resist pattern is obtained.

  In this step, the development method may be either alkali development or organic solvent development. In general, an exposed portion is removed by alkali development to form a positive resist pattern, and an unexposed portion is removed by organic solvent development to form a negative resist pattern. By using the photoresist composition, it is possible to form a resist pattern having a high LDO with a low LWR, a rectangular cross-sectional shape and a high resolution while exhibiting a wide depth of focus in both alkali development and organic solvent development. .

As developer,
In the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine , Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, and 1,5-diazabicyclo- [ 4.3.0] -5-nonene, an alkaline aqueous solution in which at least one selected from the group consisting of alkaline compounds is dissolved. The concentration of the alkaline aqueous solution is preferably 10% by mass or less. When the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer. An organic solvent can also be added to the alkaline aqueous solution.
In the case of organic solvent development, examples of the developer include one or more of the solvents exemplified as the [E] solvent of the above-described photoresist composition. As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  After the development, the formed resist pattern is preferably washed with a rinse solution. As the rinse solution, water is preferable in the case of alkali development, and pure water is more preferable. In the case of organic solvent development, alcohol solvents and ester solvents are preferable, monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable, 1-hexanol, 2-hexanol, 2-heptanol, 4-methyl-2 -Pentanol is more preferred.

  As a cleaning method, for example, a method of continuously applying a rinse liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinse liquid for a predetermined time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

<Polymer>
The polymer of the present invention is a polymer having a structural unit represented by the above formula (1). Since the said polymer has the above-mentioned specific structural unit, it can be used suitably as a polymer component of the above-mentioned photoresist composition of this invention.

<Compound>
The compound of the present invention is represented by the above formula (i). Since the said compound has the above-mentioned specific structure, it can be conveniently used as a monomer which gives the structural unit (I) of the above-mentioned polymer.

  Since the said polymer and the said compound are demonstrated in the term of the [A] polymer of the above-mentioned photoresist composition, description is abbreviate | omitted here.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The measuring method of various physical property values is shown below.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis for determining the content ratio of each constituent unit of the polymer was measured using a nuclear magnetic resonance apparatus (JNM-ECX400, manufactured by JEOL Ltd.).

<Synthesis of Compound (i)>
Compounds (i-1) to (i-3) (compounds represented by the following formulas (i-1) to (i-3)) as compounds (i) were synthesized according to the following reaction scheme.

In the case of the synthesis of compound (i-1), R ⁴ is an α-methyl-α-butyrolactone-yl group. R ⁵ is a methyl group.
In the case of the synthesis of compound (i-2), R ⁴ is a 3-hydroxyadamantan-1-yl group. R ⁵ is a methyl group.
In the case of synthesis of compound (i-3), R ⁴ is a 2-hydroxyethyl group. R ⁵ is a methyl group.

[Example 1] (Synthesis of Compound (i-1))
A dry 3 L reactor equipped with a dropping funnel and condenser was charged with 94.1 g (1.44 mol) of zinc powder (special grade, manufactured by Wako Pure Chemical Industries, Ltd.), brought to a nitrogen atmosphere, and then added with 1.3 L of THF and magnetic. While stirring with a stirrer, 6.3 mL (50 mmol) of chlorotrimethylsilane was added and stirred at 20 ° C. to 25 ° C. for 10 minutes. A solution prepared by dissolving 142.2 g (1.0 mol) of α-acetyl-α-methyl-γ-butyrolactone (a compound represented by the following formula (Y-1)) in 100 mL of THF was added thereto. Next, dropwise addition of a solution prepared by dissolving 231.7 g (1.2 mol) of ethyl (2-bromomethyl) acrylate in 100 mL of THF was started from a dropping funnel at 25 ° C. After dropping for 3 minutes, the temperature of the reaction solution rose to 40 ° C., so the reactor was cooled with a water bath. Then, it dripped so that reaction temperature might maintain the range of 30 to 40 degreeC. It took 2 hours to complete the dropping. It stirred for 30 minutes after completion | finish of dripping. After confirming the completion of the reaction by gas chromatography, the reaction solution was cooled to 25 ° C. Next, 1 L of a saturated aqueous ammonium chloride solution was added to the reaction solution, mixed, and stirred for 1 hour to stop the reaction. The resulting salt and excess zinc not used in the reaction were removed by celite filtration, and the resulting solution was concentrated using an evaporator. When ethyl acetate and a saturated aqueous sodium hydrogen carbonate solution were added to this concentrated solution with stirring, a white precipitate was formed. The white precipitate was removed by filtration, and then the organic layer was recovered using a separatory funnel. The obtained organic layer was dried, concentrated under reduced pressure, and purified by column chromatography to obtain 191 g of compound (i-1) (yield 90.9%).

[Examples 2 and 3] (Synthesis of compounds (i-1) and (i-2))
In Example 1, instead of α-acetyl-α-methyl-γ-butyrolactone (the above compound (Y-1)), 1-acetyl-3-hydroxyadamantane represented by the same number of moles (the following formula (Y-2 ) Or 1-hydroxybutane-3-one (a compound represented by the following formula (Y-3)), respectively, in the same manner as in Example 1, except that the following formula (i-2) ) And (i-3) were synthesized respectively.

<Synthesis of polymer>
Each monomer used for the synthesis of [A] polymer and [D] fluorine atom-containing polymer is shown below.

[[A] Synthesis of polymer]
[Example 4] (Synthesis of polymer (A-1))
Compound (M-1) 8.20 g (45 mol%), compound (M-2) 3.65 g (15 mol%), compound (i-1) 1.95 g (10 mol%) and compound (M- 3) 6.19 g (30 mol%) is dissolved in 2-butanone 40 g, and further AIBN 0.30 g (2 mol% based on the total number of moles of the above compound) as a polymerization initiator is dissolved in the monomer. A solution was prepared. A 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, then filtered and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (yield: 14.5 g, Yield 73%). Mw of the polymer (A-1) was 7,200, and Mw / Mn was 1.52. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from the compounds (M-1), (M-2), (i-1) and (M-3) were 44.5 mol% and 15 respectively. 0.1 mol%, 10.3 mol% and 30.1 mol%. The content rate of the low molecular weight component in this polymer (A-1) was 0.04 mass%.

[Example 5] (Synthesis of polymer (A-2))
8.01 g (45 mol%) of the compound (M-1), 3.57 g (15 mol%) of the compound (M-2), 2.38 g (10 mol%) of the compound (i-2) and the compound (M- 3) 6.04 g (30 mol%) is dissolved in 40 g of 2-butanone, and 0.30 g of AIBN as a polymerization initiator (2 mol% based on the total number of moles of the above compound) is further dissolved. A solution was prepared. A 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-2) (yield 14.8 g, Yield 74%). Mw of the polymer (A-2) was 7,200, and Mw / Mn was 1.54. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from the compounds (M-1), (M-2), (i-2) and (M-3) was 44.9 mol%, 15 0.0 mol%, 10.3 mol% and 29.8 mol%. The content rate of the low molecular weight component in this polymer (A-2) was 0.04 mass%.

[Example 6] (Synthesis of polymer (A-3))
Compound (M-1) 8.41 g (45 mol%), compound (M-2) 3.75 g (15 mol%), compound (i-3) 1.49 g (10 mol%) and compound (M- 3) 6.35 g (30 mol%) is dissolved in 2-butanone 40 g, and further AIBN 0.31 g (2 mol% based on the total number of moles of the above compound) as a polymerization initiator is dissolved in the monomer. A solution was prepared. A 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-3) (yield 14.0 g, Yield 70%). Mw of the polymer (A-3) was 7,100, and Mw / Mn was 1.51. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from the compounds (M-1), (M-2), (i-3) and (M-3) were 45.1 mol% and 15 respectively. 0.1 mol%, 9.8 mol% and 30.0 mol%. The content rate of the low molecular weight component in this polymer (A-3) was 0.04 mass%.

[Synthesis Example 1] (Synthesis of polymer (a-1))
Compound (M-1) 8.10 g (45 mol%), Compound (M-2) 3.61 g (15 mol%), Compound (M-4) 2.17 g (10 mol%) and Compound (M- 3) 6.12 g (30 mol%) is dissolved in 2-butanone 40 g, and further AIBN 0.30 g (2 mol% based on the total number of moles of the above compound) as a polymerization initiator is dissolved in the monomer. A solution was prepared. A 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (a-1) (yield 15.2 g, Yield 76%). Mw of the polymer (a-1) was 7,200, and Mw / Mn was 1.52. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from the compounds (M-1), (M-2), (M-4) and (M-3) were 45.0 mol% and 15 respectively. And 0.31 mol%, 9.6 mol% and 30.1 mol%. The content rate of the low molecular weight component in this polymer (a-1) was 0.04 mass%.

[[D] Synthesis of fluorine atom-containing polymer]
[Synthesis Example 2] (Synthesis of Polymer (D-1))
79.9 g (70 mol%) of the compound (M-5) and 20.91 g (30 mol%) of the compound (M-6) are dissolved in 100 g of 2-butanone, and dimethyl 2, as a polymerization initiator is further dissolved. A monomer solution was prepared by dissolving 4.77 g of 2′-azobisisobutyrate. A 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. After transferring this polymerization reaction liquid to a 2 L separatory funnel, 150 g of n-hexane was used to dilute this polymerization reaction solution uniformly, 600 g of methanol was added and mixed, and then 30 g of distilled water was added. The mixture was further shaken, and the mixture was allowed to stand for 30 minutes. Thereafter, the lower layer was recovered and solvent substitution was performed to obtain a propylene glycol monomethyl ether acetate solution of the polymer (D-1) (yield 60%). Mw of the polymer (D-1) was 7,200, and Mw / Mn was 2.00. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from the compounds (M-5) and (M-6) were 71.1 mol% and 28.9 mol%, respectively. The content rate of the low molecular weight component in this polymer (D-1) was 0.07 mass%.

<Preparation of photoresist composition>
Each component used for preparation of the photoresist composition is shown below.

[[B] acid generator]
B-1: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate (compound represented by the following formula (B-1))

[[C] acid diffusion controller]
C-1: Triphenylsulfonium 10-camphorsulfonate (compound represented by the following formula (C-1))

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone

[[F] uneven distribution promoter]
F-1: γ-butyrolactone

[Example 7] (Preparation of photoresist composition (J-1))
[A] 100 parts by mass of (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 30 as an acid diffusion controller Mol% (mol% based on [B] acid generator), [D] 3 parts by mass of (D-1) as a fluorine atom-containing polymer, [E] 2,240 parts by mass of (E-1) as a solvent, and (E-2) 960 parts by mass and [F] 30 parts by mass of (F-1) as an uneven distribution accelerator were mixed to prepare a photoresist composition (J-1).

[Examples 8 and 9 and Comparative Example 1] (Preparation of photoresist compositions (J-2) and (J-3) and (CJ-1))
Photoresist compositions (J-2) to (J-3) and (CJ-1) were prepared in the same manner as in Example 1 except that the components having the types and contents shown in Table 1 were used.

<Formation of resist pattern>
[In case of alkali development]
Using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a lower antireflection film forming composition (ARC66, manufactured by Brewer Science) was applied, and then heated at 205 ° C. for 60 seconds. As a result, a lower antireflection film having a thickness of 105 nm was formed. Each photoresist composition was applied onto the lower antireflection film using the spin coater, and then PB was performed at 90 ° C. for 60 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 90 nm. Next, this resist film is 40 nm under an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON). Exposure was through a line and space (1L1S) mask pattern. After exposure, PEB was performed at 85 ° C. for 60 seconds. Thereafter, development was performed with a 2.38 mass% TMAH aqueous solution, followed by washing with water and drying to form a positive resist pattern. Here, using the 40 nm 1L1S mask pattern, the exposure amount at which a 40 nm 1 L1S resist pattern is formed was determined as the optimum exposure amount.

[In the case of organic solvent development]
In the above “in the case of alkali development”, the same as in the case of “alkaline development” except that n-butyl acetate was used instead of the 2.38 mass% TMAH aqueous solution as the developer and the step of washing with water was eliminated. Thus, a negative resist pattern was formed.

<Evaluation>
Each photoresist composition was evaluated by measuring each resist pattern formed above. A scanning electron microscope (S-9380, manufactured by Hitachi High-Technologies Corporation) was used for measuring the resist pattern. The evaluation results are shown in Table 2.

[LWR performance]
The formed resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance. The LWR performance is better as the value is smaller. The LWR performance is “good” when there is an improvement of the LWR performance of 10% or more (which means that the value of the LWR performance is 90% or less) compared to the case of the photoresist composition of Comparative Example 1. When the improvement in LWR performance was less than 10%, it was evaluated as “bad”.

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure amount is defined as the resolution. The smaller the value, the better the resolution. The resolution is “good” when there is a resolution improvement of 10% or more compared to the photoresist composition of Comparative Example 1 (which means that the resolution value is 90% or less). When the improvement in image quality was less than 10%, it was evaluated as “bad”.

[Rectangularity of the cross-sectional shape]
The cross-sectional shape of the resist pattern resolved at the optimum exposure amount is observed, the line width La on the resist film surface of the resist pattern and the line width Lb in the intermediate portion in the height direction of the resist film are measured, and La / The value of Lb was calculated. This value is “good” when 0.9 ≦ (La / Lb) ≦ 1.1, and when (La / Lb) <0.9 or 1.1 <(La / Lb), It was evaluated as “bad”.

[Depth of focus]
In the resist pattern resolved at the optimum exposure amount, the dimension when the focus is changed in the depth direction is measured, and the pattern dimension is 90% to 110% of the standard without any bridge or residue. The margin was defined as the depth of focus. The depth of focus indicates that the larger the value, the better. The depth of focus is evaluated as “good” when the depth of focus value is improved by 10% or more as compared with the photoresist composition of Comparative Example 1, and “bad” when the depth of focus improvement is less than 10%. did.

  As is clear from the results in Table 2, the photoresist compositions of the examples have LWR performance, resolution, and depth of focus both in the case of alkali development and organic solvent development, as compared with the photoresist compositions of the comparative examples. It turns out that it improves. In addition, the photoresist compositions of the examples showed good rectangularity of the cross-sectional shape of the resist pattern, whereas the photoresist compositions of the comparative examples also showed that the rectangularity of the cross-sectional shape was poor. .

  According to the photoresist composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern that is excellent in LWR, resolution, and cross-sectional rectangularity while exhibiting excellent depth of focus. Therefore, a fine pattern can be formed with high accuracy and stability by a pattern forming method using the photoresist composition with respect to radiation such as KrF excimer laser or ArF excimer laser. The photoresist composition and the pattern forming method using the photoresist composition can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (10)

[A] A polymer having a structural unit represented by the following formula (1), and [B] a photoresist composition containing an acid generator.

(In Formula (1), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).) The photoresist composition according to claim 1, wherein the specific group (a) is represented by the following formula (2).

(In Formula (2), Y is a chain hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, a group having a lactone structure having 4 to 20 ring members, and 4 ring members. A group having a cyclic carbonate structure of -20, a group having a sultone structure having 4 to 20 ring members, a group having a cyclic sulfone structure having 4 to 20 ring members, a group having a lactam structure having 4 to 20 ring members, and 4 ring members It is an (n + 1) -valent group obtained by combining at least one selected from the group consisting of a group having a sultam structure of -20 and a group having a cyclic sulfonimide structure having 4 to 20 ring members, or a combination thereof. _{^{R p -OH, -R q -COOH,}} -R r -SO 3 H, -R s -CN, -R t -COOR A, -R u -OCOOR B and ^-R v _-SO 2 oR ^C, halogen atom Or halogen having 1 to 20 carbon atoms Is a hydrocarbon group ^.R p to R ^v are each independently a divalent hydrocarbon group of a single bond or a C 1 to 20 ^.R A, ^{R B} and ^{R C,} the equation (1 N is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, or cyclic When it contains a group having a sulfonimide structure, it is an integer of 0 to 3, and Y is a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, or a lactam structure. Or a group having a cyclic sulfonimide structure is an integer of 1 to 3. When n is 2 or more, a plurality of Xs may be the same or different. You can have me.) R ⁴ and R ⁵ are a group having a lactone structure, a group having a cyclic carbonate structure, a group having a sultone structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, a cyclic sulfonimide structure The photoresist composition according to claim 1, comprising a group having an alicyclic group or an alicyclic hydrocarbon group. The photoresist composition according to claim 1, wherein R ⁴ and R ⁵ contain a hydroxy group. The photoresist composition according to any one of claims 1 to 4, wherein R ⁴ is the specific group (a), and R ⁵ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. object.   [A] The photoresist composition according to any one of claims 1 to 5, wherein the polymer further has a structural unit containing an acid-dissociable group. (1) A step of forming a resist film using the photoresist composition according to any one of claims 1 to 6;
(2) A resist pattern forming method comprising: exposing the resist film; and (3) developing the exposed resist film. The polymer which has a structural unit represented by following formula (1).

(In Formula (1), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).) A compound represented by the following formula (i).

(In formula (i), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom, a fluorine atom, a hydroxy group, or a monovalent carbon atom having 1 to 20 carbon atoms. It is a hydrogen group, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded, and a is an integer of 1 to 6. In the case where a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently a monovalent specific group (a) having a polarity, hydrogen It is an atom or a monovalent hydrocarbon group having 1 to 20. The specific group (a) has a hydroxy group, a carboxy group, a sulfo group, a cyano group, a halogen atom, a group having a lactone structure, or a cyclic carbonate structure. Group, group having sultone structure, cyclic sulfo Group having a structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a, -OSO 2 R b, - _{^{SO 2 R c, -CONR α R}} d, -NR β COR e, at least one _{of ^-SO} 2 NR _γ R ^f, is selected from the group consisting of ^-NR δ SO ₂ R ^g and _{^-SO 2} NR _ε SO 2 R ^h R ^A , R ^B and R ^C are each independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{a to} R ^h are each ^a group containing a species. Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. any least one of ^{R 4} and ^{R 5} Is a specific group (a).) The manufacturing method of the compound represented by the following formula (i) which has a process with which the compound represented by the following formula (ia) and the compound represented by the following formula (ib) are made to react.

(In Formula (ia), Formula (ib), and Formula (i), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently a hydrogen atom or a fluorine atom. , A hydroxy group or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R ² and R ³ are bonded to each other to form a ring structure having 3 to 10 carbon atoms together with the carbon atom to which they are bonded. A is an integer of 1 to 6. However, when a is 2 or more, a plurality of R ² and R ³ may be the same or different, and R ⁴ and R ⁵ are each independently , A monovalent specific group having polarity (a), a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, the specific group (a) being a hydroxy group, a carboxy group, a sulfo group, a cyano group, A halogen atom, a group having a lactone structure, a group having a cyclic carbonate structure, Group having emission structure, a group having a cyclic sulfone structure, a group having a lactam structure, a group having a sultam structure, a group having a cyclic sulfonimide _{^{structure, -COOR A, -OCOOR B, -SO}} 2 OR C, -OCOR a , -OSO ₂ R ^b , -SO ₂ R ^c , -CONR ^α R ^d , -NR ^β COR ^e , -SO ₂ NR ^γ R ^f , -NR ^δ SO ₂ R ^g, and -SO ₂ NR ^ε SO ₂ R ^h Each of R ^A , R ^B and R ^C is independently a non-acid-dissociable monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{a to} R ^h are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^{α to} R ^ε are each independently a hydrogen atom or a monovalent hydrocarbon having 1 to 10 carbon atoms. of a hydrocarbon group. However, R ⁴及At least one of R ^5, a specific group (a) .R 'is a monovalent hydrocarbon radical .E is a halogen atom.)