JP2017026960A - Radiation-sensitive resin composition and method for forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation-sensitive resin composition capable of improving various lithographic performances and a method for forming a resist pattern using the composition.SOLUTION: The radiation-sensitive resin composition comprises: a polymer having a structural unit including an acid dissociable group; and a radiation-sensitive acid generator. The polymer is obtained by radical polymerization using a chain-transfer agent represented by formula (1). In the formula, A represents -CH-, an oxygen atom, -CHO- or -NR-, and when A is -CH-, X is -R, -OR,-SR, -SiRRR, -SnRRR, -SOR, -SORor -PO(OR)(OR), and when A is an oxygen atom, X is -R; and when A is -CHO- or -NR-, X is -OR; and Z represents =CRRor a sulfur atom.SELECTED DRAWING: None

Description

  The present invention relates to a radiation-sensitive resin composition and a resist pattern forming method.

  Radiation sensitive compositions used for microfabrication by lithography are exposed to irradiated parts such as deep ultraviolet rays such as ArF excimer laser light and KrF excimer laser light, electromagnetic waves such as extreme ultraviolet rays (EUV), and charged particle beams such as electron beams. An acid is generated in the substrate, and a chemical reaction using the acid as a catalyst causes a difference in the dissolution rate of the exposed portion and the unexposed portion with respect to the developer, thereby forming a pattern on the substrate.

  Such a radiation-sensitive composition has high resolution of a resist pattern to be formed as processing technology is miniaturized, and has excellent Line Width Roughness (LWR) performance and Line Edge Roughness (LER) performance, and Mask. It is required that an error enhancement factor (MEEF) performance, a depth of focus, and an exposure margin are excellent, and a highly accurate pattern can be obtained with a high yield. In response to such demands, the types and molecular structures of polymers, acid generators, and other components used in the radiation-sensitive composition have been studied, and further their combinations have been studied in detail (Japanese Patent Laid-Open No. Hei 11-). 125907, JP-A-8-146610 and JP-A-2000-298347).

  However, at the present time when the resist pattern is miniaturized to a level of 45 nm or less, the required level of the performance is further increased, and various lithography performances such as LWR and LER are required to be excellent. However, it is difficult to meet these requirements with the conventional radiation-sensitive resin composition.

Japanese Patent Laid-Open No. 11-125907 JP-A-8-146610 JP 2000-298347 A

  The present invention has been made based on the above circumstances, and an object thereof is to provide a radiation-sensitive resin composition capable of improving various lithography performances and a resist pattern forming method using the same. There is.

（式（１）中、Ｒ^１は、水素原子又は炭素数１〜２０の１価の有機基である。Ａは、−ＣＨ_２−、酸素原子、−ＯＣＨ_２−又は−ＮＲ^２−である。Ｒ^２は、水素原子又は炭素数１〜１０の１価の炭化水素基である。Ｒ^１及びＲ^２は、互いに合わせられ、Ｒ^１が結合する炭素原子及びＲ^２が結合する窒素原子と共に環員数３〜１０の環構造を形成してもよい。Ａが−ＣＨ_２−の場合、Ｘは、−Ｒ^３、−ＯＲ^３、−ＳＲ^３、−ＳｉＲ^３Ｒ^４Ｒ^５、−ＳｎＲ^３Ｒ^４Ｒ^５、−ＳＯＲ^３、−ＳＯ_２Ｒ^３又は−ＰＯ（ＯＲ^３）（ＯＲ^４）である。Ｒ^３、Ｒ^４及びＲ^５は、それぞれ独立して、炭素原子が結合手を有する炭素数１〜２０の１価の有機基である。Ａが酸素原子の場合、Ｘは、−Ｒ^３である。Ａが−ＯＣＨ_２−又は−ＮＲ^２−の場合、Ｘは、−ＯＲ^３である。Ｚは、＝ＣＲ^６Ｒ^７又は硫黄原子である。Ｒ^６及びＲ^７は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。） The invention made to solve the above problems is a polymer having a structural unit containing an acid-dissociable group (hereinafter also referred to as “structural unit (I)”) (hereinafter also referred to as “[A] polymer”). And a radiation-sensitive acid generator (hereinafter also referred to as “[B] acid generator”), and a radiation-sensitive resin composition (hereinafter also referred to as “radiation-sensitive resin composition (I)”). The [A] polymer is obtained by radical polymerization using a chain transfer agent represented by the following formula (1) (hereinafter also referred to as “chain transfer agent (X)”).

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. A is —CH ₂ —, an oxygen atom, —OCH ₂ — or —NR ² —. R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, R ¹ and R ² are combined with each other, together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. A ring structure having 3 to 10 ring members may be formed, and when A is —CH ₂ —, X is —R ³ , —OR ³ , —SR ³ , —SiR ³ R ⁴ R ⁵ , —SnR ^3. R ⁴ R ⁵ , —SOR ³ , —SO ₂ R ^3, or —PO (OR ³ ) (OR ⁴ ), wherein R ³ , R ^4, and R ⁵ each independently have a carbon atom bond. when a monovalent organic group having 1 to 20 carbon atoms .A is an oxygen atom, X is -R ³ .A is -OCH ₂ - -NR ² is - case, X is -OR ³ .Z is = ^CR 6 ^{R 7} or a sulfur atom in which .R ⁶ and ^{R 7} are each independently a hydrogen atom or 1 to carbon atoms 20 monovalent organic groups.)

（式（２）中、Ｒ^１は、水素原子又は炭素数１〜２０の１価の有機基である。Ａ^１は、＝ＣＨ_２、酸素原子又は＝ＮＲ^２である。Ｒ^２は、水素原子又は炭素数１〜１０の１価の炭化水素基である。Ｒ^１及びＲ^２は、互いに合わせられ、Ｒ^１が結合する炭素原子及びＲ^２が結合する窒素原子と共に環員数３〜１０の環構造を形成してもよい。Ｚ’は、−ＣＲ^６Ｒ^７−又は硫黄原子である。Ｒ^６及びＲ^７は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。＊^１は、上記［Ａ−１］重合体の主鎖の一方の末端に結合する部位を示す。） Another invention made in order to solve the above problems is a polymer containing a structural unit (I) (hereinafter also referred to as “[A-1] polymer”) and a radiation-sensitive acid generator. A radiation-sensitive resin composition (hereinafter also referred to as “radiation-sensitive resin composition (II)”), wherein the [A-1] polymer is bonded to one end of the main chain, and the following formula ( 2) (hereinafter also referred to as “terminal group (I-1)”).

(In Formula (2), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. A ¹ is ═CH ₂ , an oxygen atom, or ═NR ^2. R ² is hydrogen. An atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, R ¹ and R ² are combined with each other and have 3 to 10 ring members together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. A ring structure may be formed, and Z ′ is —CR ⁶ R ⁷ — or a sulfur atom, and R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * ¹ represents a site bonded to one end of the main chain of the above [A-1] polymer.)

（式（４）中、Ｒ^１は、水素原子又は炭素数１〜２０の１価の有機基である。Ｚ’は、−ＣＲ^６Ｒ^７−又は硫黄原子である。Ｒ^６及びＲ^７は、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。＊^３は、上記［Ａ−２］重合体の主鎖の一方の末端に結合する部位を示す。 Another invention made in order to solve the above problems is a polymer containing a structural unit (I) (hereinafter also referred to as “[A-2] polymer”) and a radiation-sensitive acid generator. A radiation-sensitive resin composition (hereinafter also referred to as “radiation-sensitive resin composition (III)”), wherein the [A-2] polymer is bonded to one end of the main chain, and the following formula ( 4) (hereinafter also referred to as “terminal group (I-2)”).

(In Formula (4), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Z ′ is —CR ⁶ R ⁷ — or a sulfur atom. R ⁶ and R ⁷ are Each independently represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, * ³ represents a site bonded to one end of the main chain of the [A-2] polymer.

  Another invention made to solve the above-mentioned problems comprises a step of forming a resist film, a step of exposing the resist film, and a step of developing the exposed resist film, and the radiation resistance of the resist film. It is a resist pattern formation method formed with a resin composition.

  Here, the “organic group” refers to a group containing at least one carbon atom. The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure. “Number of ring members” means the number of atoms constituting the ring of an aromatic ring structure, aromatic heterocyclic structure, alicyclic structure and aliphatic heterocyclic structure. In the case of a polycyclic ring structure, this polycyclic ring The number of atoms to be played. “Main chain” refers to the longest chain composed of atoms in a polymer. The term “end” in “one end of the main chain” and “the other end of the main chain” means the relatively longest bond chain of the polymer formed when the polymer is synthesized by polymerizing monomers. The carbon atom at the end.

  According to the radiation sensitive resin composition and resist pattern forming method of the present invention, various groups can be introduced into the polymer. As a result, the radiation-sensitive resin composition containing such a polymer can form resist patterns excellent in various lithography performances. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Radiation sensitive resin composition (I)>
The radiation sensitive resin composition (I) contains a [A] polymer and a [B] acid generator. The radiation-sensitive resin composition (I) includes a [C] acid diffusion controller and a polymer having a higher fluorine atom content than the [A] polymer as suitable components (hereinafter also referred to as “[D] polymer”). [E] A solvent and [F] an uneven distribution promoter may be contained, and other optional components may be contained as long as the effects of the present invention are not impaired. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I) and obtained by radical polymerization using the chain transfer agent (X). By radical polymerization using the chain transfer agent (X), a group derived from the C (R ¹ ) (= Z) -A- moiety in the chain transfer agent (X) is one end of the main chain of the [A] polymer. And the group derived from the -X moiety in the chain transfer agent (X) is introduced into the other end of the main chain of the [A] polymer. [A] The polymer includes a structural unit containing at least one of a lactone structure, a cyclic carbonate structure and a sultone structure (hereinafter, also referred to as “structural unit (II)”) and phenol in addition to the structural unit (I). May have a structural unit containing a functional hydroxyl group (hereinafter also referred to as “structural unit (III)”), and may have other structural units other than the structural units (I) to (III). .

  Hereinafter, the chain transfer agent (X) and the structural unit will be described in this order. The group derived from the chain transfer agent (X) will be described in the radiation-sensitive resin composition (II) and the radiation-sensitive resin composition (III) described later.

<Chain transfer agent (X)>
The chain transfer agent (X) is a chain transfer agent represented by the following formula (1). [A] polymer is obtained by radical polymerization using chain transfer agent (X). Therefore, various groups derived from the chain transfer agent (X) can be introduced into the [A] polymer. As a result, the radiation-sensitive resin composition (I) containing such a [A] polymer can form resist patterns excellent in various lithography performances.

In the above formula (1), ^{R 1} is a monovalent organic group hydrogen atom or a C 1-20. A is —CH ₂ —, an oxygen atom, —OCH ₂ — or —NR ² —. R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹ and R ² may be combined with each other to form a ring structure having 3 to 10 ring members together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. When A is —CH ₂ —, X is —R ³ , —OR ³ , —SR ³ , —SiR ³ R ⁴ R ⁵ , —SnR ³ R ⁴ R ⁵ , —SOR ³ , —SO ₂ R ³ or it is ^{-PO (OR 3) (OR 4} ). R ³ , R ⁴ and R ⁵ are each independently a monovalent organic group having 1 to 20 carbon atoms in which the carbon atom has a bond. When A is an oxygen atom, X is -R ^3. When A is —OCH ₂ — or —NR ² —, X is —OR ³ . Z is ═CR ⁶ R ⁷ or a sulfur atom. R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

-SOR ³ above and X is -S (O) - is a group having the structure, _-SO 2 ^{R 3} is -S _{(O) 2} - is a group having the structure.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ include, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a carbon-carbon boundary of this hydrocarbon group, or a terminal on the bond side. And groups containing a divalent heteroatom-containing group (a), a group obtained by substituting part or all of the hydrogen atoms of the hydrocarbon group and the group (a) with a monovalent heteroatom-containing group, and the like.

  Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the number of carbon atoms. Examples thereof include 6-20 monovalent aromatic hydrocarbon groups.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, alkyl groups such as t-butyl groups;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a methylcyclopentyl group, an ethylcyclopentyl group, a cyclohexyl group, and a cyclooctyl group. An alkyl group;
A monocyclic cycloalkenyl group such as a cyclobutenyl group, a cyclopentenyl group, or a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples thereof include aralkyl groups such as a benzyl group, a phenethyl group, a cumyl group, and a naphthylmethyl group.

Examples of the divalent heteroatom-containing group include —O—, —CO—, —S—, —CS—, —SO ₂ —, —NR′—, a combination of two or more thereof, and the like. Is mentioned. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the group (a) containing a divalent heteroatom-containing group at the terminal between the carbon-carbon or bond side of the monovalent hydrocarbon group having 1 to 20 carbon atoms include -CN, -CONHR ⁸ ,- ^{OCONHR 8, -OR 8, -COR 8} , -SR 8, -CSR 8, -SO 2 R 8, -NR 8, -OCOR 8, -COOR 8, -CH 2 OR 8, -CH 2 OCOR 8, - etc. CH ₂ COOR ^8, and the like. R ⁸ is a hydrocarbon group having 1 to 18 carbon atoms.

  Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group, sulfanyl group (-SH) and the like. .

Examples of the hydrocarbon group having 1 to 18 carbon atoms represented by R ⁸ include hydrocarbon groups having 1 to 18 carbon atoms among those exemplified as the hydrocarbon group of R ¹ .

As R ¹ , from the viewpoint of further improving various lithography performances, a hydrogen atom, a hydrocarbon group, and a group containing a divalent heteroatom-containing group at the terminal between carbon-carbon of the hydrocarbon group or the bond side. Preferably, a hydrogen atom, —R ⁸ , —CN, —CONHR ⁸ , —OCONHR ⁸ , —OR ⁸ , —OCOR ⁸ , —COOR ⁸ , —CH ₂ OR ⁸ , —CH ₂ OCOR ⁸ and —CH ₂ COOR ⁸ are More preferably, a hydrogen atom, —R ⁸ and —COOR ⁸ are more preferable, a hydrogen atom, an alkyl group, an aryl group, an alkyloxycarbonyl group and an alkylcycloalkyloxycarbonyl group are particularly preferable, a hydrogen atom, a methyl group, a phenyl group, Methyloxycarbonyl group, methylcyclopentyloxycarbonyl group and ethylcyclopentyloxycarbo Nyl groups are even more particularly preferred.

Further, as the R ^1, from the viewpoint of ease of chain transfer, electron-withdrawing groups are preferred. Here, the “electron withdrawing group” is a group having a tendency to attract an electron, for example, a group having a tendency to attract an electron from an atom in a position close to the electron withdrawing group in the molecule. .

Examples of the electron withdrawing group include the above-described phenyl group, —CN, —CONHR ⁸ , —OCONHR ⁸ , —OR ⁸ , —OCOR ⁸ , —COOR ⁸ , —CH ₂ OR ⁸ , —CH ₂ OCOR ⁸ and — Other than these, CH ₂ COOR ⁸ and, for example, a halogen atom, —NO ₂ , —CN, —SO ₂ OR ^{8 and the} like can be mentioned.

Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ² include groups having 1 to 10 carbon atoms among the groups exemplified as the hydrocarbon group of R ¹ .

As the A, from the viewpoint of ease of chain transfer, -CH ₂ -, oxygen atom and -OCH ₂ - are preferred.

Aligned the R ¹ and R ² together, the ring structure of ring members 3 to 10 carbon atoms and R ² is formed together with the nitrogen atom bonded to R ¹ is bonded, for example, nitrogen-containing ring members 3-20 Examples thereof include an aliphatic heterocyclic structure.

Examples of the nitrogen-containing aliphatic heterocyclic structure having 3 to 20 ring members include azacyclopropane structure, azacyclobutane structure, azacyclopentane structure (pyrrolidine structure), azacyclohexane structure (piperidine structure), azacycloheptane structure, aza Monocyclic azacycloalkane structures such as cyclooctane structure and azacyclodecane structure;
An azabicyclo [2.2.1] heptane structure, an azabicyclo [2.2.2] octane structure, an azabicyclo [4.4.0] decane structure, an azatricyclo [3.3.1.1 ^3,7 ] decane structure, etc. A polycyclic azacycloalkane structure;
Azaoxacycloalkane structures such as azaoxacyclobutane structure, azaoxacyclohexane structure (including morpholine structure), azaoxacyclooctane structure;
Monocyclic azacycloalkene structures such as azacyclobutene structure, azacyclopentene structure, azacyclohexene structure, azacycloheptene structure, azacyclooctene structure, azacyclodecene structure,
Monocyclic azacycloalkadiene structures such as azacyclohexadiene structure, azacycloheptadiene structure, azacyclooctadiene structure, azacyclodecadiene structure;
Examples thereof include polycyclic azacycloalkene structures such as an azabicyclo [2.2.1] heptene structure, an azabicyclo [2.2.2] octene structure, and an azabicyclo [4.4.0] decene structure.

Aligned the R ¹ and R ² together, the ring structure of ring members 3 to 10 carbon atoms and R ² is formed together with the nitrogen atom bonded to R ¹ are attached aza cycloalkadiene structure of a single ring Preferably, an azacycloheptadiene structure is more preferable.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ³ , R ⁴ and R ⁵ include the same groups as the monovalent organic group exemplified as R ¹ .

R ³ , R ^4, and R ⁵ include a chain hydrocarbon group, an aromatic hydrocarbon group, a group having a hetero atom-containing group between carbon-carbons of the chain hydrocarbon group, and a bond of an aromatic hydrocarbon group. A group having a heteroatom-containing group at the terminal on the hand side is preferable, and an alkyl group, an aralkyl group, a group having a carbonyloxy group between carbon and carbon of the alkyl group, and a carbonyloxy group at the terminal on the hand side of the aryl group A group is more preferable, and a methyl group, a benzyl group, a cumyl group, a methyloxycarbonyl group and a phenylcarbonyloxy group are more preferable.

In the case where A is —CH ₂ —, as the above X, from the viewpoint of further improving various lithography performances, —R ³ , —SR ³ , —SiR ³ R ⁴ R ⁵ , —SnR ³ R ⁴ R ⁵ , — SO ₂ R ³ and —PO (OR ³ ) (OR ⁴ ) are preferable, a tertiary hydrocarbon group, a group having a hetero atom-containing group between carbon and carbon of the tertiary hydrocarbon group, an alkylsulfanyl group, tri More preferred are alkylsilyl group, trialkylstannyl group, alkylsulfonyl group and dialkylphosphono group, 2-methoxycarbonyl-i-propan-2-yl group, cumyl group, methylsulfanyl group, trimethylsilyl group, trimethylstannyl group More preferred are a methylsulfonyl group and a dimethylphosphono group. When A is an oxygen atom, X is preferably an aromatic hydrocarbon group, more preferably an aralkyl group, and further preferably a benzyl group from the viewpoint of further improving various lithography performances. When A is —OCH ₂ — or —NR ² —, X is preferably an alkyloxy group or an arylcarbonyloxy group from the viewpoint of further improving various lithography performances, and more preferably a methyloxy group or a phenylcarbonyloxy group. preferable.

Examples of the monovalent organic group represented by R ⁶ and R ⁷ include the same groups as the monovalent organic group exemplified as R ¹ .

R ⁶ and R ⁷ are preferably a hydrogen atom from the viewpoint of easy chain transfer.

Z is preferably ═CH _{2 or a} sulfur atom from the viewpoint of improving various lithography performances.

  Examples of the chain transfer agent (X) include chain transfer agents represented by the following formulas (1-1) to (1-18) (hereinafter referred to as “chain transfer agents (X-1) to (X-18)”). Say).

  Among these, chain transfer agents (X-1) to (X-11) are preferable from the viewpoint of further improving various lithography performances.

<Structural unit (I)>
[A] The polymer has the structural unit (I). The structural unit (I) is a structural unit containing an acid dissociable group. Examples of the structural unit (I) include a structural unit represented by the following formula (a-1) (hereinafter also referred to as “structural unit (I-1)”), and a structure represented by the following formula (a-2). A unit (hereinafter also referred to as “structural unit (I-2)”). In the following formula (a-1), a group represented by —CR ^A2 R ^A3 R ^A4 is an acid dissociable group. In the following formula (a-2), a group represented by -CR ^A6 R ^A7 R ^A8 is an acid dissociable group.

In the above formula (a-1), R ^A1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^A2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^A3 and R ^A4 each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, or have 3 to 20 ring members formed together with carbon atoms to which these groups are combined with each other. Represents an alicyclic structure.

In formula (a-2), R ^A5 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^A6 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^A7 and R ^A8 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. L ^A is a single bond, -O -, - COO- or -CONH-.

R ^A1 is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^A2 , R ^A3 , R ^A4 , R ^A6 , R ^A7 and R ^A8 include, for example, monovalent chain carbonization having 1 to 20 carbon atoms. Examples thereof include a hydrogen group, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ^A2 , R ^A3 , R ^A4 , R ^A6 , R ^A7 and R ^A8 include, for example, a methyl group, an ethyl group, and an n-propyl group. Alkyl groups such as i-propyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ and R ¹⁹ include, for example, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. A monocyclic cycloalkyl group such as;
A monocyclic cycloalkenyl group such as a cyclopentenyl group, a cyclohexenyl group, a cyclooctenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^A2 , R ^A3 , R ^A4 , R ^A6 , R ^A7 and R ^A8 include, for example, a monocycle such as a cyclopentyl group and a cyclohexyl group. A cycloalkyl group of
A monocyclic cycloalkenyl group such as a cyclopentenyl group and a cyclohexenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R ^A2 , R ^A3 , R ^A4 , R ^A6 , R ^A7 and R ^A8 include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Group, an aryl group such as an anthryl group;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group and anthrylmethyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms configured together with the carbon atom to which these groups are combined and bonded to each other include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclo Monocyclic cycloalkane structures such as octane structures;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

R ^A2 is preferably a chain hydrocarbon group and an alicyclic hydrocarbon group, more preferably an alkyl group and a cycloalkyl group, a methyl group, an ethyl group, a propyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and More preferred is an adamantyl group.

As R ^A3 and R ^A4 , an alkyl group, a monocyclic cycloalkane structure, a norbornane structure, and an adamantane structure constituted by combining these groups are preferable, and a methyl group, an ethyl group, a cyclopentane structure, a cyclohexane structure, and An adamantane structure is more preferred.

R ^A5 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, from the viewpoint of the copolymerizability of the monomer that provides the structural unit (I).

R ^A6 is preferably a chain hydrocarbon group.

The ^R monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by ^A7 and ^{R A8,} for example the ^{R A2, R A3, R A4} , R A6, R A7 and 1 number of carbon atoms in ^{R A8} Examples of the monovalent hydrocarbon group of 20 include those containing an oxygen atom between carbon and carbon.

R ^A7 and R ^A8 are preferably a chain hydrocarbon group and an alicyclic hydrocarbon group containing an oxygen atom.

As the ^{L A,} a single bond and -COO- is more preferably a single bond.

  Examples of the structural unit (I-1) include structural units represented by the following formulas (a-1-a) to (a-1-d) (hereinafter referred to as “structural units (I-1-a) to (I -1-d) ”) and the like.

  Examples of the structural unit (I-2) include a structural unit represented by the following formula (a-2-a) (hereinafter also referred to as “(I-2-a)”).

In the formulas (a-1-a) to (a-1-d), R ^{A1 to} R ^A4 have the same meanings as the formula (a-1). n _a is an integer of 1 to 4. In the above formula (a-2-a), R ^{A5 to} R ^A8 have the same ^meanings as the above formula (a-2).

The n _a, preferably 1, 2 and 4, more preferably 1.

  Examples of the structural units (I-1-a) to (I-1-d) include structural units represented by the following formulas.

In the above formula, R ^A1 has the same ^meaning as the above formula (a-1).

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

In the above formula, R ^A5 has the same ^{meaning as} in the above formula (a-2).

  The structural unit (I) is preferably the structural unit (I-1), more preferably the structural units (I-1-b) and (I-1-c), and 1-alkyl-1-cycloalkyl (meth). More preferred are structural units derived from acrylates and structural units derived from 2- (adamantan-1-yl) propan-2-yl (meth) acrylate.

  [A] As a minimum of the content rate of structural unit (I) with respect to all the structural units which constitute a polymer, 10 mol% is preferred, 20 mol% is more preferred, 25 mol% is still more preferred, and 30 mol% is especially preferable. On the other hand, the upper limit of the content is preferably 80 mol%, more preferably 70 mol%, further preferably 65 mol%, particularly preferably 60 mol%. By making the said content rate into the said range, the melt | dissolution contrast to the developing solution of the exposed part of a radiation sensitive resin composition (I) and the unexposed part can fully be ensured, As a result, various lithography performances Will be improved.

<Structural unit (II)>
The structural unit (II) is a structural unit containing at least one of a lactone structure, a cyclic carbonate structure, and a sultone structure (excluding those included in the structural unit (I)). [A] The polymer further includes the structural unit (II) in addition to the structural unit (I), so that the solubility in the developer can be further adjusted, and as a result, various lithography performances are further improved. Can be made. Moreover, the adhesiveness of the resist pattern formed from a radiation sensitive resin composition (I) and a board | substrate 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 (II) include a structural unit represented by the following formula.

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

As said ^RAL , a hydrogen atom and a methyl group are preferable from the viewpoint of the copolymerizability of the monomer which gives structural unit (II), and a methyl group is more preferable.

  Among these, the structural unit (II) is preferably a structural unit containing a norbornane lactone structure, a structural unit containing an oxanorbornane lactone structure, or a structural unit containing a γ-butyrolactone structure. Derived structural unit, structural unit derived from oxanorbornanelactone-yl (meth) acrylate, structural unit derived from γ-butyrolactone-yl (meth) acrylate, and γ-butyrolactone-3-ylcyclohexane-1-yl (meth) A structural unit derived from acrylate is more preferred.

  [A] When the polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) with respect to all the structural units constituting the [A] polymer is preferably 1 mol%, and 5 mol%. Is more preferable, 10 mol% is further more preferable, and 25 mol% is especially preferable. On the other hand, the upper limit of the content is preferably 85 mol%, more preferably 80 mol%, further preferably 75 mol%, and particularly preferably 70 mol%. By making the said content rate into the said range, the adhesiveness to the board | substrate of the resist pattern formed from a radiation sensitive resin composition (I) can be improved more. When the said content rate is less than the said minimum, the adhesiveness to the board | substrate of the resist pattern formed from a radiation sensitive resin composition (I) may fall. When the said content rate exceeds the said upper limit, various lithography performance may fall.

<Structural unit (III)>
The structural unit (III) is a structural unit containing a phenolic hydroxyl group. When KrF excimer laser light, EUV, electron beam, or the like is used as the radiation to be irradiated, the [A] polymer further includes the structural unit (III) in addition to the structural unit (I), so that the radiation sensitive resin The sensitivity of the composition (I) is improved. As a result, various lithography performances can be further improved.

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

In the above formula (af), R ^AF1 is a hydrogen atom or a methyl group. ^LAF is a single bond, —COO—, —O— or —CONH—. R ^AF2 is a monovalent organic group having 1 to 20 carbon atoms. n _f1 is an integer of 0 to 3. When n _f1 is 2 or 3, the plurality of R ^AF2 may be the same or different. n _f2 is an integer of 1 to 3. However, n _f1 + n _f2 is 5 or less. n _af is an integer of 0-2.

R ^AF1 is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer giving the structural unit (III).

The L ^AF, single bond and -COO- are preferred.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^AF2 include the same groups as the monovalent organic group exemplified as R ¹ .

  Among these, a monovalent chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is more preferable.

As the _{n f1,} preferably an integer of 0 to 2, more preferably 0 and 1, 0 it is more preferred.

As said _nf2 , 1 and 2 are preferable and 1 is more preferable.

As said _naf , 0 and 1 are preferable and 0 is more preferable.

  As the structural unit (III), structural units represented by the following formulas (f-1) to (f-6) (hereinafter also referred to as “structural units (III-1) to (III-6)”). Is preferred.

In the above formulas (f-1) to (f-6), R ^AF1 has the same ^meaning as the above formula (af).

  Among these, structural units (III-1) and (III-2) are preferable, and (III-1) is more preferable.

  [A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) to the total structural units constituting the [A] polymer is preferably 1 mol%, and preferably 10 mol%. Is more preferable, and 20 mol% is more preferable. On the other hand, as an upper limit of the said content rate, 90 mol% is preferable, 80 mol% is more preferable, and 75 mol% is further more preferable. By making the content rate of structural unit (III) into the said range, the radiation sensitive resin composition (I) can improve various lithography performance more.

  The structural unit (III) is obtained by polymerizing a monomer obtained by substituting the hydrogen atom of the —OH group of hydroxystyrene with an acetyl group, and then subjecting the obtained polymer to a hydrolysis reaction in the presence of an amine. Or the like.

<Other structural units>
[A] The polymer may have other structural units other than the structural units (I) to (III). Examples of the other structural units include structural units having a hydroxy group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, and the like. Among these, a structural unit having a hydroxy group and a structural unit having a carboxy group are preferable, and a structural unit having a hydroxy group is more preferable.

  Examples of other structural units include structural units represented by the following formula.

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

  [A] When the polymer has other structural units, the lower limit of the content ratio of the other structural units to the total structural units constituting the [A] polymer is preferably 1 mol%, more preferably 20 mol%. Preferably, 40 mol% is more preferable. On the other hand, as an upper limit of the said content rate, 80 mol% is preferable, 75 mol% is more preferable, and 70 mol% is further more preferable. By making the content rate of another structural unit into the said range, the solubility to the developing solution of a [A] polymer can be adjusted more appropriately. If the content ratio of other structural units exceeds the above upper limit, pattern formability may be deteriorated.

  The radiation sensitive resin composition (I) may contain one or more [A] polymers.

<[A] Polymer Synthesis Method>
[A] The polymer is obtained by radical polymerization using a monomer that gives each structural unit, a radical polymerization initiator, and the like in a solvent in the presence of the chain transfer agent (X).

  The chain transfer agent (X) may be synthesized according to a known method, or a commercially available product may be used.

Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropyl). Azo radical initiators such as propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate;
And peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like.

  Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

Examples of the solvent used for the polymerization 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, methyl ethyl ketone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, propylene glycol monomethyl ether;
Examples of amide solvents include chain amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, and N-methylpropionamide. And amides such as cyclic amides such as N-methylpyrrolidone and N, N′-dimethylimidazolidinone.

  Of these, ketones, alcohol solvents and ethers are preferred. The solvent used for these polymerizations may be used alone or in combination of two or more.

  As a minimum of reaction temperature in the above-mentioned polymerization, it is usually 40 ° C and 50 ° C is preferred. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually 1 hour. The upper limit of the reaction time is usually 48 hours, preferably 24 hours.

  [A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 2,500, and 3,000. Is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [A] By making Mw of a polymer into the said range, various lithography performance improves more. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained.

  [A] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, and 1.1 is preferable. The upper limit of Mw / Mn is usually 5, preferably 3 and more preferably 2.5.

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: For example, two “G2000HXL”, one “G3000HXL”, one “G4000HXL” manufactured by Tosoh Corporation Column temperature: 40 ° C.
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates acid upon irradiation. Due to the action of the acid, the acid dissociable group of the [A] polymer is dissociated to generate a polar group such as a carboxy group, and there is a difference in the solubility of the [A] polymer in the developer between the exposed part and the unexposed part. Arise. As a result, a resist pattern can be formed from the radiation sensitive resin composition (I). The contained form of the [B] acid generator in the radiation sensitive resin composition (I) may be a low molecular compound form (hereinafter also referred to as “[B] acid generator” as appropriate) or a polymer. It may be in the form of an acid generating group incorporated as part of or both of these forms.

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

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

  [B] Specific examples of the acid generator include compounds described in paragraphs [0080] to [0113] of JP-A-2009-134088.

  [B] The acid generator preferably contains a compound represented by the following formula (b). [B] When the acid generator contains a compound having the following structure, the lithography property can be further improved.

In the above formula (b), R ^B1 is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ^B2 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent group including an alicyclic structure having 6 or more ring members represented by R ^B1 include monocyclic groups such as a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group. A cycloalkyl group;
A monocyclic cycloalkenyl group such as a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ^B1 include a group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacyclohexyl group, an azacycloheptyl group, a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The lower limit of the number of ring members of the group represented by R ^B1 is preferably 8, more preferably 9, and even more preferably 10 from the viewpoint of further improving various lithography performances. On the other hand, the upper limit of the number of ring members is preferably 15, and more preferably 13.

Among these, R ^B1 is preferably a monovalent group containing an alicyclic structure having 9 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members, an adamantyl group, a hydroxyadamantyl group , Norbornanelactone-yl group, 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group, adamantane-1-yloxycarbonyl group, norbornane sultone-2-yloxycarbonyl And the group and piperidin-1-ylsulfonyl group are more preferred.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ^B2 include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which is substituted with a fluorine atom.

Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 , 2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group, 1,1,2,2-tetrafluorohexanediyl group, 1,1,2-trifluorobutanediyl group And 1,1,2,2,3,3-hexafluoropropanediyl group is more preferred.

The monovalent radiation-sensitive onium cation represented by X ⁺ is a cation that is decomposed by irradiation with exposure light. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiation-sensitive onium cation and sulfonate anions. Examples of the monovalent radiation-sensitive onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples include radiation-sensitive onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (ba), a tetrahydrothiophenium cation represented by the following formula (bb), and an iodonium cation represented by the following formula (bc) preferable.

In the above formula (ba), R ^B3 , R ^B4 and R ^B5 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted group. An aromatic hydrocarbon group having 6 to 12 carbon atoms, —OSO ₂ —R ^BB1 or —SO ₂ —R ^BB2 , or a ring structure in which two or more of these groups are combined with each other . R ^BB1 and R ^BB2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. b1, b2 and b3 are each independently an integer of 0 to 5. R ^B3 to R ^B5 and, if a plurality ^{R BB1} and ^{R BB2} are each the plurality of ^R B3 ^{to R B5} and ^{R BB1} and ^{R BB2} may each be the same or different.

In the above formula (bb), R ^B6 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. It is. b4 is an integer of 0-7. If R ^B6 is plural, the plurality of R ^B6 may be the same or different, and plural R ^B6 may represent a constructed ring aligned with each other. R ^B7 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. b5 is an integer of 0-6. If R ^B7 is plural, R ^B7 may be the same or different, and plural R ^B7 may represent a keyed configured ring structure. n _b is an integer of 0 to 3.

In the above formula ( ^bc ), R ^B8 and R ^B9 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon _group, or an -OSO ^{2 -R BB3} or _-SO 2 ^{-R BB4,} or two or more are combined with each other configured ring of these groups. R ^BB3 and R ^BB4 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. b6 and b7 are each independently an integer of 0 to 5. ^{R B8,} R B9, R ^BB3 and when ^{R BB4} is plural respective plurality of ^{R B8, R B9, R BB3} and ^{R BB4} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^{B3 to} R ^B9 include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group.

Examples of the unsubstituted branched alkyl group represented by R ^{B3 to} R ^B9 include i-propyl group, i-butyl group, sec-butyl group, t-butyl group and the like.

Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{B3 to} R ^B5 , R ^B8 and R ^B9 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group and naphthyl group; benzyl group, Examples include aralkyl groups such as phenethyl group.

Examples of the unsubstituted aromatic hydrocarbon group represented by R ^B6 and R ^B7 include a phenyl group, a tolyl group, and a benzyl group.

  Examples of the substituent that may be substituted for the hydrogen atom of the alkyl group and aromatic hydrocarbon group include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, and a cyano group. Nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like. Among these, a halogen atom is preferable, and a fluorine atom is more preferable.

Examples of R ^{B3 to} R ^B9 include an unsubstituted linear or branched alkyl group, a fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group, —OSO ₂ —R ^BB5 , —SO ₂ —. R ^BB5 is preferable, a fluorinated alkyl group and an unsubstituted monovalent aromatic hydrocarbon group are more preferable, and a fluorinated alkyl group is more preferable. R ^BB5 is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As b1, b2 and b3 in the above formula (ba), integers of 0 to 2 are preferable, 0 and 1 are more preferable, and 0 is more preferable.
As b4 in the above formula (bb), an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 1 is more preferable. As b5, the integer of 0-2 is preferable, 0 and 1 are more preferable, and 0 is still more preferable. The n _b, is preferably an integer of 1 to 3, more preferably 2 and 3, 2 is more preferable.
As b6 and b7 in the above formula (bc), an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 0 is more preferable.

As said X ^<+> , the cation represented by the said formula (ba) is preferable, and a triphenylsulfonium cation is more preferable.

  Examples of the acid generator represented by the above formula (b) include compounds represented by the following formulas (b-1) to (b-16) (hereinafter, “compounds (b-1) to (b-16)”. And so on).

  [B] Among these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt and a tetrahydrothiophenium salt, and still more preferably a compound (b-12) and a compound (b-15).

  [B] When the acid generator is a [B] acid generator, the content of the [B] acid generator with respect to 100 parts by mass of the polymer [A] is used from the viewpoint of improving the shape of the resist pattern to be formed. As a minimum, 0.1 mass part is preferable, 0.5 mass part is more preferable, 1 mass part is further more preferable, and 3 mass parts is especially preferable. On the other hand, the upper limit of the content of the [B] acid generator is preferably 40 parts by mass, more preferably 35 parts by mass, and still more preferably 30 parts by mass. [B] By making content of an acid generator into the said range, the sensitivity and developability of radiation sensitive resin composition (I) improve, As a result, various lithographic performance can be improved more. [B] 1 type (s) or 2 or more types can be used for an acid generator.

<[C] Acid diffusion controller>
The radiation sensitive resin composition (I) may contain a [C] acid diffusion controller as required. The [C] acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, and has the effect of suppressing undesirable chemical reactions in the unexposed areas. As a result, the storage stability of the resulting radiation sensitive resin composition (I) is further improved. Further, the resolution as a resist is further improved, and a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing can be suppressed, and a radiation-sensitive resin composition (I ) Is obtained. [C] The content of the acid diffusion controller in the radiation-sensitive resin composition (I) is a form of an acid diffusion controller which is a low molecular compound as described later (hereinafter also referred to as “acid diffusion controller” as appropriate). ), In the form of acid diffusion control groups incorporated as part of the polymer, or in both forms.

  Examples of the [C] acid diffusion controller include a compound represented by the following formula (c-1) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule. (Hereinafter also referred to as “nitrogen-containing compound (II)”), compounds having three nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds Etc.

In the above formula (c-1), R ^C1 , R ^C2 and R ^C3 each independently represent a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. It is.

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine;
Dialkylamines such as di-n-butylamine;
Trialkylamines such as triethylamine;
And aromatic amines such as aniline.

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

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

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. It is done.

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

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine, pyrazine, and pyrazole.

  A compound having an acid dissociable group can also be used as the acid diffusion controller. Examples of the acid diffusion controller having such an acid dissociable group include N- (t-butoxycarbonyl) piperidine, N- (t-butoxycarbonyl) imidazole, N- (t-butoxycarbonyl) benzimidazole, N— (T-butoxycarbonyl) -2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N -(T-butoxycarbonyl) diphenylamine, N- (t-butoxycarbonyl) -4-hydroxypiperidine and the like.

  Further, as the acid diffusion controller, a photodegradable base that is exposed to light and generates a weak acid by exposure can also be used. Examples of the photodegradable base include an onium salt compound that loses acid diffusion controllability by being decomposed by exposure. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (c-2), an iodonium salt compound represented by the following formula (c-3), and the like.

In formula (c-2) and formula (c-3), R ^{C4 to} R ^C8 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ⁻ and Q ⁻ are each independently represented by OH ⁻ , R ^CC1 —COO ⁻ , R ^CC1 —SO ₃ ⁻ , an anion represented by the following formula (c-4), or the following formula (c-5). Anion. However, R ^CC1 is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (c-4), R ^C9 is a linear or branched alkyl group having 1 to 12 carbon atoms, in which some or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 1 carbon atoms. 12 linear or branched alkoxyl groups. n _c1 is an integer of 0-2. When n _c1 is 2, the plurality of R ^C9 may be the same as or different from each other.

In the above formula (c-5), R ^C10 represents a linear or branched alkyl group having 1 to 12 carbon atoms, in which some or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 1 carbon atoms. 12 linear or branched alkoxyl groups. _nc2 is an integer of 0-2. When n _c2 is 2, the plurality of R ^C10 may be the same as or different from each other.

  When the radiation sensitive resin composition (I) contains a [C] acid diffusion controller, the lower limit of the content of the [C] acid diffusion controller with respect to 100 parts by mass of the polymer [A] is 0.1. Part by mass is preferable, and 0.3 part by mass is more preferable. On the other hand, as an upper limit of the said content, 20 mass parts is preferable, 15 mass parts is more preferable, and 10 mass parts is further more preferable.

<[D] Polymer>
[D] The polymer is a polymer having a higher fluorine atom content than the [A] polymer. The radiation-sensitive composition (I) contains the [D] polymer, so that when the resist film is formed, the distribution of the resist film surface depends on the oil-repellent characteristics of the [D] polymer in the film. There is a tendency to be unevenly distributed in the vicinity. Therefore, at the time of immersion exposure, it is possible to prevent the acid generator, the acid diffusion control agent and the like from eluting into the immersion medium. Further, due to the water repellency characteristics of the [D] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the radiation sensitive resin composition (I) contains the [D] polymer, a resist film suitable for the immersion exposure method can be formed.

When the radiation sensitive resin composition (I) contains a [D] polymer, the lower limit of the fluorine atom content of the [D] polymer is preferably 1% by mass, more preferably 2% by mass. % By mass is more preferable, and 7% by mass is particularly preferable. On the other hand, as an upper limit of the said content rate, 60 mass% is preferable, 40 mass% is more preferable, and 30 mass% is further more preferable. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

  [D] The fluorine atom content in the polymer is not particularly limited, and may be bonded to the main chain or bonded to the side chain, but may be a structural unit containing a fluorine atom (hereinafter referred to as “structural unit (V ) ”)). [D] In addition to the structural unit (V), the polymer preferably has a structural unit containing an acid dissociable group from the viewpoint of further improving various lithography performances. Examples of the structural unit containing an acid dissociable group include the structural unit (I) in the [A] polymer.

  [D] The polymer preferably has an alkali dissociable group. [D] When the polymer has an alkali-dissociable group, the resist film surface can be effectively changed from hydrophobic to hydrophilic during alkali development, and various lithography performances are further improved. The “alkali dissociable group” is a group that replaces a hydrogen atom of a carboxy group, a hydroxy group, etc., and dissociates in an alkaline aqueous solution (for example, a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C.). Refers to the group.

  The structural unit (V) includes a structural unit represented by the following formula (ff1) (hereinafter also referred to as “structural unit (Va)”) and a structural unit represented by the following formula (ff2) (hereinafter referred to as “structure”). Unit (Vb) ”) is preferred. The structural unit (V) may have one or more structural units (Va) and structural units (Vb).

<Structural unit (Va)>
The structural unit (Va) is a structural unit represented by the following formula (ff1). [D] A polymer can adjust a fluorine atom content rate by having a structural unit (Va).

In the above formula (ff1), R ^F1 represents a hydrogen atom, a methyl group or a trifluoromethyl group. L ^F1 is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH—, or —O—CO—NH—. R ^F2 is a monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms.

As R ^F1 , a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable, from the viewpoint of copolymerizability of the monomer that gives the structural unit (Va).

The L ^F1 is preferably —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—, more preferably —CO—O—.

Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms represented by R ^F2 include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, 2, 2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n-butyl group Perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

Examples of the monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^F2 include a monofluorocyclopentyl group, a difluorocyclopentyl group, a perfluorocyclopentyl group, a monofluorocyclohexyl group, and a difluorocyclopentyl group. Perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Among these, R ^F2 is preferably a fluorinated chain hydrocarbon group, such as 2,2,2-trifluoroethyl group and 1,1,1,3,3,3-hexafluoro-2-propyl. Groups are more preferred.

  [D] When the polymer has a structural unit (Va), the lower limit of the content ratio of the structural unit (Va) to the total structural units constituting the [D] polymer is preferably 3 mol%, and 5 mol%. Is more preferable. On the other hand, as an upper limit of the said content rate, 90 mol% is preferable, 70 mol% is more preferable, and 50 mol% is further more preferable. By setting it as such a content rate, the fluorine atom content rate of a [D] polymer can be adjusted more appropriately.

<Structural unit (Vb)>
The structural unit (Vb) is a structural unit represented by the following formula (ff2). [D] By having the structural unit (Vb), the polymer can adjust the fluorine atom content and change the water repellency and hydrophilicity before and after alkali development.

In the above formula (ff2), R ^F3 is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^F4 is a single bond, a (u + 1) valent hydrocarbon group having 1 to 20 carbon atoms, or an oxygen atom, a sulfur atom, —NR ^FF1 —, a carbonyl group, —CO— at the terminal of R ^F5 side of this hydrocarbon group. It has a structure in which O- or -CO-NH- is bonded. R ^FF1 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^F5 is a single bond or a divalent organic group having 1 to 20 carbon atoms. L ^F2 is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. L ^F3 is an oxygen atom, —NR ^FF2 —, —CO—O— * or —SO ₂ —O— *. R ^FF2 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * Indicates a site that binds to R ^F6 . R ^F6 is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. u is an integer of 1 to 3. However, when u is 2 or 3, a plurality of R ^F5 , L ^F2 , L ^F3 and R ^F6 may be the same or different. When L ^F2 is a single bond, R ^F6 is a group containing a fluorine atom.

As R ^F3 , a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable, from the viewpoint of copolymerization of the monomer that gives the structural unit (Vb).

Examples of the (u + 1) -valent hydrocarbon group having 1 to 20 carbon atoms represented by R ^F4 include u hydrogen atoms from the monovalent hydrocarbon group exemplified as R ^A2 in the above formula (a-1). And the like except for.

  As said u, 1 and 2 are preferable and 1 is more preferable.

As R ^F4 , when u is 1, a single bond and a divalent hydrocarbon group are preferable, a single bond and an alkanediyl group are more preferable, a single bond and an alkanediyl group having 1 to 4 carbon atoms are more preferable, Single bonds, methanediyl groups and propanediyl groups are particularly preferred.

The divalent organic group having 1 to 20 carbon atoms represented by R ^F5 is, for example, one monovalent organic group having 1 to 20 carbon atoms exemplified as R ^A2 in the above formula (a-1). And a group in which a hydrogen atom is removed.

As R ^F5 , a group having a single bond and a lactone structure is preferable, a group having a single bond and a polycyclic lactone structure is more preferable, and a group having a single bond and a norbornane lactone structure is more preferable.

Examples of the divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by L ^F2 include a fluoromethanediyl group, a difluoromethanediyl group, a fluoroethanediyl group, a difluoroethanediyl group, and a tetrafluoroethanediyl group. Fluorinated alkanediyl groups such as a group, hexafluoropropanediyl group, octafluorobutanediyl group;
Examples thereof include fluorinated alkenediyl groups such as a fluoroethenediyl group and a difluoroethenediyl group. Among these, a fluorinated alkanediyl group is preferable, and a difluoromethanediyl group is more preferable.

As the ^{L F3,} oxygen atom, -CO-O- * and _-SO 2 -O- * are preferred, -CO-O- * is more preferable.

  Examples of the structural unit (Vb) include structural units represented by the following formulas (ff2-1) to (ff2-3).

In the above formulas (ff2-1) to (ff2b-3), R ^{F4 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F3 , L ^F2 , R ^F6 and u are synonymous with the above formula (ff2). When u is 2 or 3, the plurality of L ^F2 and R ^F6 may be the same or different.

  [D] When the polymer has a structural unit (Vb), the lower limit of the content ratio of the structural unit (Vb) with respect to all structural units constituting the [D] polymer is preferably 10 mol%, and 20 mol%. Is more preferable, and 40 mol% is further more preferable. On the other hand, as an upper limit of the said content rate, 90 mol% is preferable, 85 mol% is more preferable, and 80 mol% is further more preferable. By setting it as such a content rate, the water repellency before and behind alkali development of the resist film surface formed from the radiation sensitive resin composition (I), hydrophilicity, etc. can be adjusted more appropriately.

  [D] When the polymer has a structural unit (V), the lower limit of the content ratio of the structural unit (V) relative to all structural units constituting the [D] polymer is preferably 10 mol%, and 15 mol%. Is more preferable, and 20 mol% is more preferable. On the other hand, as an upper limit of the said content rate, 90 mol% is preferable, 85 mol% is more preferable, and 80 mol% is further more preferable.

  [D] As a minimum of the content rate of the structural unit containing an acid dissociable group with respect to all the structural units which constitute a polymer, 10 mol% is preferred, 15 mol% is more preferred, and 20 mol% is still more preferred. On the other hand, as an upper limit of the said content rate, 85 mol% is preferable, 80 mol% is more preferable, and 75 mol% is further more preferable. [D] Various lithography performance can be further improved by making the content rate of the structural unit containing the acid dissociable group in a polymer into the said range.

  When the radiation sensitive resin composition (I) contains a [D] polymer, the lower limit of the content of the [D] polymer with respect to 100 parts by mass of the [A] polymer is preferably 0.1 parts by mass. 0.2 parts by mass is more preferable, 0.5 parts by mass is further preferable, and 1 part by mass is particularly preferable. On the other hand, the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, further preferably 15 parts by mass, and particularly preferably 10 parts by mass.

  The [D] polymer can be synthesized by the same method as the above-described [A] polymer.

  [D] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but the lower limit thereof is preferably 1,000, more preferably 2,000, and 2,500. Is more preferable, and 3,000 is particularly preferable. On the other hand, the upper limit of the weight average molecular weight is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [D] By making Mw of a polymer into the said range, the applicability | paintability and various lithography performance of a radiation sensitive resin composition (I) improve more. [D] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [D] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may be lowered.

  [D] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1. On the other hand, the upper limit of the ratio is preferably 5, more preferably 3, and even more preferably 2.

<[E] solvent>
The radiation sensitive resin composition (I) may contain [E] solvent as needed. [E] The solvent dissolves or disperses the [A] polymer and [B] acid generator, and the [C] acid diffusion controller, [D] polymer and other optional components contained as necessary. If it can do, 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.

Examples of the alcohol solvent include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A polyhydric alcohol solvent having 3 to 18 carbon atoms such as 1,2-propylene glycol;
Examples thereof include C3-C19 polyhydric alcohol partial ether solvents such as propylene glycol monoethyl ether.

Examples of ether solvents include dialiphatic ether solvents such as diethyl ether, dipropyl ether, and 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 the ketone solvent 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. Chain ketone solvents such as ketone, di-iso-butyl ketone, trimethylnonanone, acetophenone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
And diketone solvents such as 2,4-pentanedione and acetonylacetone.

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

Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;
lactone solvents such as γ-butyrolactone and valerolactone;
Polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate;
Polycarboxylic acid diester solvents such as diethyl oxalate;
Examples thereof include carbonate solvents such as dimethyl carbonate and diethyl carbonate.

Examples of the hydrocarbon solvent include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, and cyclohexane. , Aliphatic hydrocarbon solvents such as methylcyclohexane;
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, polyhydric alcohol partial ether carboxylate solvents and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are more preferable. [E] A solvent can be used individually by 1 type or in mixture of 2 or more types.

<[F] Localization promoter>
The radiation sensitive resin composition (I) may contain a [F] uneven distribution promoter as needed. [F] The uneven distribution accelerator has the effect of segregating the [D] polymer more efficiently on the resist film surface when the radiation sensitive resin composition (I) contains the [D] polymer. Is. By adding the [F] uneven distribution accelerator to the radiation sensitive resin composition (I), the amount of the water-repellent polymer additive added can be reduced as compared with the conventional amount. Therefore, the elution of components from the resist film to the immersion liquid can be further suppressed without impairing various lithography performances, and the immersion exposure can be performed at a higher speed by high-speed scanning. It is possible to improve the hydrophobicity of the resist film surface that suppresses the defects derived from immersion. Examples of such [F] uneven distribution promoters include low molecular compounds having a relative dielectric constant of 30 to 200 and a boiling point of 100 ° C. at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

  Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

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

  Examples of the nitrile compound include succinonitrile.

  Examples of the polyhydric alcohol include glycerin.

  [F] The uneven distribution accelerator is preferably a lactone compound, more preferably γ-butyrolactone, from the viewpoint of further improving various lithography performances.

  When the radiation sensitive resin composition (I) contains a [F] uneven distribution accelerator, the lower limit of the content of the [F] uneven distribution accelerator is as follows. 10 mass parts is preferable, 15 mass parts is more preferable, 20 mass parts is further more preferable, and 25 mass parts is especially preferable. As an upper limit of content of the said [F] uneven distribution promoter, 500 mass parts is preferable with respect to 100 mass parts of [A] polymers, 400 mass parts is more preferable, 300 mass parts is further more preferable, 200 mass Part is particularly preferred.

<Other optional components>
The radiation sensitive resin composition (I) may contain other optional components in addition to the above [A] to [F] components. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds, and sensitizers. Each of these other optional components may be used alone or in combination of two or more.

<Surfactant>
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include “KP341” from Shin-Etsu Chemical Co., Ltd., “Polyflow No. 75, No. 95” from Kyoeisha Chemical Co., Ltd., “F-Top EF301, EF303, EF352 ", DIC's" Megafuck F171, F173 ", Sumitomo 3M's" Florard FC430, FC431 ", Asahi Glass Industrial" Asahi Guard AG710, Surflon S- " 82, SC-101, SC-102, the SC-103, the SC-104, the SC-105, the SC-106 ", and the like. When the radiation sensitive resin composition (I) contains a surfactant, the content of the surfactant is usually 2 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

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

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. When the radiation sensitive resin composition (I) contains an alicyclic skeleton-containing compound, the content of the alicyclic skeleton-containing compound is usually 5 parts by mass or less with respect to 100 parts by mass of the [A] polymer. .

<Sensitizer>
The sensitizer exhibits an action of increasing the amount of acid generated from the [B] acid generator and the like, and has the effect of improving the “apparent sensitivity” of the radiation-sensitive resin composition (I).

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used alone or in combination of two or more. When the radiation sensitive resin composition (I) contains a sensitizer, the content of the sensitizer is usually 2 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

<Method for Preparing Radiation Sensitive Resin Composition (I)>
The radiation sensitive resin composition (I) includes, for example, [A] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent, [F] as required. It can be prepared by mixing the uneven distribution promoter and other optional components at a predetermined ratio, and preferably filtering through a membrane filter having a pore size of about 0.2 μm. As a minimum of solid content concentration of radiation sensitive resin composition (I), 0.1 mass% is preferred, 0.5 mass% is more preferred, 1 mass% is still more preferred, and 1.5 mass% is especially preferred. . As an upper limit of solid content concentration of radiation sensitive resin composition (I), 50 mass% is preferable, 30 mass% is more preferable, 20 mass% is further more preferable, 10 mass% is especially preferable. Here, the “solid content concentration” of the radiation-sensitive resin composition (I) is the mass of the component excluding the solvent from the radiation-sensitive resin composition (I) relative to the total mass of the radiation-sensitive resin composition (I). Say a fraction.

<Radiation sensitive resin composition (II)>
The radiation sensitive resin composition (II) contains a [A-1] polymer and a [B] acid generator. The radiation sensitive resin composition (II) may contain [C] acid diffusion controller, [D] polymer, [E] solvent and [F] uneven distribution accelerator as suitable components. In the range which does not impair the effect of, other arbitrary components may be contained. As the [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent and other optional components of the radiation sensitive resin composition (II), the above radiation sensitive resin composition is used. The thing similar to what was described as each component of (I) can be used. Moreover, what is preferable as each component is the same as that of the said radiation sensitive resin composition (I). Hereinafter, the [A-1] polymer will be described.

<[A-1] Polymer>
[A-1] The polymer is a polymer having a structural unit (I) and a terminal group (I-1). Since the [A-1] polymer can introduce various groups as the terminal group (I-1), the radiation-sensitive resin composition (II) containing such a [A-1] polymer. Can form various resist patterns having excellent lithography performance.

  [A-1] The polymer can be synthesized by radical polymerization using a chain transfer agent (X). The end group (I-1) derived from the chain transfer agent (X) can be introduced into the [A-1] polymer by radical polymerization using the chain transfer agent (X).

  [A-1] The polymer preferably has a terminal group (II-1) described later in addition to the terminal group (I-1). The end group (II-1) derived from the chain transfer agent (X) can be introduced into the [A-1] polymer by radical polymerization using the chain transfer agent (X).

  [A-1] The polymer may have the structural unit (II) and the structural unit (III) in addition to the structural unit (I), and other than the structural units (I) to (III). It may have a structural unit of

  As each structural unit of the [A-1] polymer, it can have the same thing as what was illustrated as each structural unit of the said [A] polymer. Moreover, the preferable thing of each structural unit is the same as that of the said [A] polymer. Hereinafter, the terminal group (I-1) and the terminal group (II-1) will be described in this order.

<Terminal group (I-1)>
The terminal group (I-1) is a group bonded to one terminal of the main chain of the [A-1] polymer and represented by the following formula (2).

In the formula (2), ^{R 1} is a monovalent organic group hydrogen atom or a C 1-20. A ¹ is ═CH ₂ , an oxygen atom or ═NR ² . R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹ and R ² may be combined with each other to form a ring structure having 3 to 10 ring members together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. Z ′ is —CR ⁶ R ⁷ — or a sulfur atom. R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * ¹ shows the site | part couple | bonded with one terminal of the principal chain of the said [A-1] polymer.

The terminal group (I-1) is a group introduced into the [A-1] polymer by radical polymerization using the chain transfer agent (X), and C (R ¹ ) (= Z in the chain transfer agent (X). ) A group derived from the -A- moiety. That, ^{R 1} in the formula (2) is derived from ^{R 1} in the formula (1). A ¹ in the above formula (2) is derived from A in the above formula (1). Z ′ in the above formula (2) is derived from Z in the above formula (1).

The monovalent organic group having 1 to 20 carbon atoms represented by R ¹ in the above formula (2) is the same monovalent organic group as the group exemplified as the organic group of R ^{1 in} the above formula (1). Is mentioned. Among these, from the viewpoint of further improving various lithography performances, a hydrogen atom, a hydrocarbon group, and a group containing a divalent heteroatom-containing group at a carbon-carbon end or a bond-side end of the hydrocarbon group are preferable. a hydrogen ^{atom, -R 8, -CN, -CONHR 8} , -OCONHR 8, -OR 8, -OCOR 8, -COOR 8, -CH 2 oR 8, -CH 2 OCOR 8 and _-CH 2 COOR ⁸ Gayori Preferably, a hydrogen atom, —R ⁸ and —COOR ⁸ are more preferable, a hydrogen atom, an alkyl group, an aryl group, an alkyloxycarbonyl group and an alkylcycloalkyloxycarbonyl group are particularly preferable, and a hydrogen atom, a methyl group, a phenyl group, methyl Oxycarbonyl group, methylcyclopentyloxycarbonyl group and ethylcyclopentyloxycarbonyl But more particularly preferred.

As the A ^1, -CH view of ease of chain transfer 2 _- and the oxygen atom is preferable.

Aligned the R ¹ and R ² together, the ring structure of ring members 3 to 10 carbon atoms and R ² is formed together with the nitrogen atom bonded to R ¹ is bonded, for example, nitrogen-containing ring members 3-20 Examples thereof include an aliphatic heterocyclic structure.

Examples of the ring structure having 3 to 10 ring members formed by combining R ¹ and R ² with each other and the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded include an azacyclopropene structure and an azacyclobutene A monocyclic azacycloalkene structure such as a structure, an azacyclopentene structure, an azacyclohexene structure, an azacycloheptene structure, an azacyclooctene structure, an azacyclodecene structure;
An azabicyclo [2.2.1] heptene structure, an azabicyclo [2.2.2] octene structure, an azabicyclo [4.4.0] decene structure, an azatricyclo [3.3.1.1 ^3,7 ] decene structure, etc. A polycyclic azacycloalkene structure;
An azaoxacycloalkene structure such as an azaoxacyclobutene structure, an azaoxacyclohexene structure, an azaoxacyclooctene structure;
Monocyclic azacycloalkadiene structures such as azacyclobutadiene structure, azacyclopentadiene structure, azacyclohexadiene structure, azacycloheptadiene structure, azacyclooctadiene structure, azacyclodecadiene structure,
Monocyclic azacycloalkatriene structures such as azacyclohexatriene structure, azacycloheptatriene structure, azacyclooctatriene structure, azacyclodecatriene structure;
Examples thereof include polycyclic azacycloalkadiene structures such as an azabicyclo [2.2.1] heptadiene structure, an azabicyclo [2.2.2] octadiene structure, and an azabicyclo [4.4.0] decadiene structure.

The ring structure having 3 to 10 ring members formed by combining R ¹ and R ² with each other and the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded is a monocyclic azacycloalkatriene structure. Preferably, an azacycloheptatriene structure is more preferable.

Z ′ is preferably —CH ₂ and a sulfur atom from the viewpoint of further improving various lithography performances.

  Examples of the terminal group (I-1) include groups represented by the following formulas (2-1) to (2-11) (hereinafter referred to as “terminal groups (I-1-1) to (I-1-11)”. ").

In the above formula, * ¹ is synonymous with the above formula (2).

  Among these, terminal groups (I-1-1) to (I-1-7) are preferable from the viewpoint of further improving various lithography performances.

<Terminal group (II-1)>
The terminal group (II-1) is a group bonded to the other terminal of the main chain of the [A-1] polymer and represented by the following formula (3).

In the above formula (3), ^{X 1,} when ^{A 1} in the formula (2) is ^{_{= CH 2, -R 3, -SiR}} 3 R 4 R 5, -SnR 3 R 4 R 5, -SOR 3, a -SO ₂ R ³ or ^{-PO (oR 3) (oR 4} ). R ³ , R ⁴ and R ⁵ are each independently a monovalent organic group having 1 to 20 carbon atoms in which the carbon atom has a bond. X ¹ is —R ³ when A ¹ in the above formula (2) is an oxygen atom. X ¹ is —OR ³ when A ¹ in the above formula (2) is ═NR ² . * ² shows the site | part couple | bonded with the other terminal of the principal chain of the said [A-1] polymer.

Said -SOR ³ of ^{X 1} is -S (O) - is a group having the structure, _-SO 2 ^{R 3} is -S _{(O) 2} - is a group having the structure.

The terminal group (II-1) is a group introduced into the [A-1] polymer by radical polymerization using the chain transfer agent (X), and is a group derived from the -X portion in the chain transfer agent (X). It is. That is, X ¹ in the above formula (3) is derived from X in the above formula (1).

In the case where A ¹ is —CH ₂ —, the above X ¹ includes —R ³ , —SR ³ , —SiR ³ R ⁴ R ⁵ , and —SnR ³ R ⁴ R ⁵ from the viewpoint of further improving various lithography performances. , —SO ₂ R ³ and —PO (OR ³ ) (OR ⁴ ) are preferred, a tertiary hydrocarbon group, a group having a heteroatom-containing group between carbon-carbons of a tertiary hydrocarbon group, an alkylsulfanyl group More preferred are a trialkylsilyl group, a trialkylstannyl group, an alkylsulfonyl group and a dialkylphosphono group, a 2-methoxycarbonyl-i-propan-2-yl group, a cumyl group, a methylsulfanyl group, a trimethylsilyl group, Nyl group, methylsulfonyl group and dimethylphosphono group are more preferable. When A ¹ is an oxygen atom, the above X ¹ is preferably an aromatic hydrocarbon group, more preferably an aralkyl group, and further preferably a benzyl group from the viewpoint of further improving various lithography performances. When A ¹ is —NR ² —, X ¹ is preferably an arylcarbonyloxy group and more preferably a phenylcarbonyloxy group from the viewpoint of further improving various lithography performances.

<[A-1] Polymer Synthesis Method>
[A-1] The polymer is obtained by polymerization using a monomer that gives each structural unit, a radical polymerization initiator and the like in the presence of the chain transfer agent (X) in a solvent. [A-1] As the chain transfer agent (X), radical polymerization initiator, solvent, etc. used in the method for synthesizing the polymer, the same ones as those used for the synthesis of [A] polymer may be used. it can. Each of these preferred ones is also the same as in the case of the synthesis of the above [A] polymer.

  As a minimum of reaction temperature in the above-mentioned polymerization, it is usually 40 ° C and 50 ° C is preferred. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually 1 hour. The upper limit of the reaction time is usually 48 hours, preferably 24 hours.

  [A-1] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 2,500, Is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [A-1] By setting the Mw of the polymer in the above range, various lithography performances are further improved. [A-1] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained.

  [A-1] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, and 1.1 is preferable. The upper limit of Mw / Mn is usually 5, preferably 3 and more preferably 2.5.

  [A-1] The terminal structure of the polymer can be confirmed by NMR.

<Method for preparing radiation-sensitive resin composition (II)>
The radiation sensitive resin composition (II) includes, for example, [A-1] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent, if necessary. [F] It can be prepared by mixing an uneven distribution promoter and other optional components at a predetermined ratio, and preferably filtering through a membrane filter having a pore size of about 0.2 μm. As a minimum of solid content concentration of radiation sensitive resin composition (II), 0.1 mass% is preferred, 0.5 mass% is more preferred, 1 mass% is still more preferred, and 1.5 mass% is especially preferred. . As an upper limit of solid content concentration of radiation sensitive resin composition (II), 50 mass% is preferable, 30 mass% is more preferable, 20 mass% is further more preferable, 10 mass% is especially preferable.

<Radiation sensitive resin composition (III)>
The radiation sensitive resin composition (III) contains a [A-2] polymer and a [B] acid generator. The radiation-sensitive resin composition (III) may contain a [C] acid diffusion controller, a [D] polymer and a [E] solvent as suitable components, and in the range not impairing the effects of the present invention, Other optional components may be contained. As the [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent, [F] uneven distribution accelerator and other optional components of the radiation sensitive resin composition (III) The same as those described as the respective components of the radiation sensitive resin composition (I) can be used. Moreover, what is preferable as each component is the same as that of the said radiation sensitive resin composition (I). Hereinafter, the [A-2] polymer will be described.

<[A-2] Polymer>
[A-2] The polymer is a polymer having a structural unit (I) and a terminal group (I-2). Since the [A-2] polymer can introduce various groups as the terminal group (I-2), the radiation-sensitive resin composition (III) containing such a [A-2] polymer. Can form various resist patterns having excellent lithography performance.

  [A-2] The polymer can be synthesized by radical polymerization using a chain transfer agent (X). The end group (I-2) derived from the chain transfer agent (X) can be introduced into the [A-2] polymer by radical polymerization using the chain transfer agent (X).

  [A-2] The polymer preferably has a terminal group (II-2) described later in addition to the terminal group (I-2). The end group (II-2) derived from the chain transfer agent (X) can be introduced into the [A-2] polymer by radical polymerization using the chain transfer agent (X).

  [A-2] The polymer may have the structural unit (II) and the structural unit (III) in addition to the structural unit (I), and other than the structural units (I) to (III). It may have a structural unit of

  [A-2] As each structural unit of a polymer, it can have the same thing as what was illustrated as each structural unit of the said [A] polymer. Moreover, the preferable thing of each structural unit is the same as that of the said [A] polymer. Hereinafter, the terminal group (I-2) and the terminal group (II-2) will be described in this order.

<Terminal group (I-2)>
The terminal group (I-2) is a group bonded to one terminal of the main chain of the [A-2] polymer and represented by the following formula (4).

In the formula (4), ^{R 1} is a monovalent organic group hydrogen atom or a C 1-20. Z ′ is —CR ⁶ R ⁷ — or a sulfur atom. R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * ³ shows the site | part couple | bonded with one terminal of the principal chain of the said [A-2] polymer.

The terminal group (I-2) is a group introduced into the [A-2] polymer by radical polymerization using the chain transfer agent (X), and C (R ¹ ) (= Z in the chain transfer agent (X). ) A group derived from the -A- moiety. That, ^{R 1} in the formula (4) is derived from ^{R 1} in the formula (1). -O-CH ₂ in the formula (4) - is derived from A in the above formula (1). Z ′ in the above formula (4) is derived from Z in the above formula (1).

Z ′ is preferably —CH ₂ from the viewpoint of further improving various lithography performances.

  Examples of the terminal group (I-2) include groups represented by the following formulas (4-1) to (4-3) (hereinafter referred to as “terminal groups (I-2-1) to (I-2-3)”. ").

In the above formula, * ³ is synonymous with the above formula (4).

  Among these, from the viewpoint of further improving various lithography performances, the terminal group (I-2-1) is preferable.

<Terminal group (II-2)>
The terminal group (II-2) is a group bonded to the other terminal of the main chain of the [A-2] polymer and represented by the following formula (5).

In the above formula (5), ^{X 2} is -OR ³ or -SR ^3. R ³ is a monovalent organic group having 1 to 20 carbon atoms in which the carbon atom has a bond. * ⁴ shows the site | part couple | bonded with the other terminal of the principal chain of the said [A-2] polymer.

The terminal group (II-2) is a group introduced into the [A-2] polymer by radical polymerization using the chain transfer agent (X), and is a group derived from the -X portion in the chain transfer agent (X). It is. That is, X ² in the above formula (5) is derived from X in the above formula (1).

X ² is preferably —OR ^3, more preferably a chain hydrocarbon group, further preferably an alkyloxy group, and particularly preferably a methyloxy group, from the viewpoint of further improving various lithography performances.

<[A-2] Polymer Synthesis Method>
[A-2] The polymer can be obtained by polymerizing a monomer giving each structural unit in a solvent using a chain transfer agent (X), a radical polymerization initiator or the like. [A-2] The chain transfer agent (X), radical polymerization initiator, solvent, etc. used in the polymer synthesis method may be the same as those used in the synthesis of [A] polymer. it can. Each of these preferred ones is also the same as in the case of the synthesis of the above [A] polymer.

  As a minimum of reaction temperature in the above-mentioned polymerization, it is usually 40 ° C and 50 ° C is preferred. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually 1 hour. The upper limit of the reaction time is usually 48 hours, preferably 24 hours.

  [A-2] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 2,500, Is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 15,000. [A-2] By setting the Mw of the polymer in the above range, various lithography performances are further improved. [A-2] When the polymer Mw is less than the lower limit, a resist film having sufficient heat resistance may not be obtained.

  [A-2] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, and 1.1 is preferable. The upper limit of Mw / Mn is usually 5, preferably 3 and more preferably 2.5.

<Method for Preparing Radiation Sensitive Resin Composition (III)>
The radiation sensitive resin composition (III) includes, for example, [A-2] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent, if necessary. [F] It can be prepared by mixing an uneven distribution promoter and other optional components at a predetermined ratio, and preferably filtering through a membrane filter having a pore size of about 0.2 μm. As a minimum of solid content concentration of radiation sensitive resin composition (III), 0.1 mass% is preferred, 0.5 mass% is more preferred, 1 mass% is still more preferred, and 1.5 mass% is especially preferred. . As an upper limit of solid content concentration of radiation sensitive resin composition (III), 50 mass% is preferable, 30 mass% is more preferable, 20 mass% is further more preferable, 10 mass% is especially preferable.

<Resist pattern formation method>
The resist pattern forming method includes a step of forming a resist film (hereinafter also referred to as “resist film forming step”), a step of exposing the resist film (hereinafter also referred to as “exposure step”), and the exposed resist film. A step of developing (hereinafter also referred to as “development step”), and the above-described resist film is made of the above-described radiation-sensitive resin composition (I), radiation-sensitive resin composition (II), or radiation-sensitive resin composition (III). ). In addition, radiation sensitive resin composition (I), radiation sensitive resin composition (II), and radiation sensitive resin composition (III) may be collectively called the said radiation sensitive resin composition.

  According to the resist pattern forming method, since the radiation sensitive resin composition is used, resist patterns excellent in various lithography performances can be formed. Hereinafter, each step of the resist pattern forming method will be described.

<Resist film formation process>
In this step, a resist film is formed from the radiation sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. 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. After application, pre-baking (PB) may be performed to volatilize the solvent in the coating film as necessary. As a minimum of PB temperature, it is usually 60 ° C and 80 ° C is preferred. As an upper limit of PB temperature, it is 140 degreeC normally and 120 degreeC is preferable. The lower limit of the PB time is usually 5 seconds, and preferably 10 seconds. The upper limit of the PB time is usually 600 seconds, and preferably 300 seconds. As a minimum of the average thickness of the resist film formed, 10 nm is preferable and 20 nm is more preferable. The upper limit of the average thickness of the resist film is preferably 1,000 nm, and more preferably 500 nm.

<Exposure process>
In this step, the resist film formed in the resist film forming step is exposed by irradiation with radiation through a photomask or the like (in some cases through an immersion medium such as water). Examples of radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and γ rays, and charged particle beams such as electron beams and α rays, depending on the line width of the target pattern. Is mentioned. Among these, far ultraviolet rays, EUV and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV and electron beams are more preferable, and ArF excimer laser light and electron beams are more preferable. .

  When the exposure is performed by immersion exposure, examples of the immersion liquid to be used 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 reduces 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 film 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.

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by exposure is dissociated. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed part and the unexposed part. As a minimum of PEB temperature, it is 50 ° C usually and 80 ° C is preferred. The upper limit of the PEB temperature is usually 180 ° C, preferably 130 ° C. The lower limit of the PEB time is usually 5 seconds, and preferably 10 seconds. The upper limit of the PEB time is usually 600 seconds, and preferably 300 seconds.

<Development process>
In this step, the resist film exposed in the exposure step is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse solution such as water or alcohol and then dry. As a development method in the development step, a positive resist pattern may be formed by development with an alkaline solution, or a negative resist pattern may be formed by development with an organic solvent-containing solution.

  As the developer used for the development, 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, Examples include an alkaline solution in which at least one alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved. Among these, TMAH liquid is preferable.

  Examples of the developing solution include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, and solvents containing organic solvents in the case of organic solvent development. As said organic solvent, the 1 type (s) or 2 or more types of the solvent enumerated as the [E] solvent of the above-mentioned radiation sensitive resin composition are mentioned, for example. Among these, ester solvents are preferable, and n-butyl acetate is more preferable. As a minimum of content of the organic solvent in a developing solution, 80 mass% is preferred, 90 mass% is more preferred, 95 mass% is still more preferred, and 99 mass% is especially preferred. Examples of components other than the organic solvent in the developer include water and silicone oil.

  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.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, each measurement in an Example and a comparative example was performed with the following method.

[Mw, Mn and Mw / Mn]
Mw and Mn used Tosoh GPC columns ("G2000HXL", "G3000HXL", "G4000HXL"), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1. Measurement was performed by GPC using monodisperse polystyrene as a standard under the analysis conditions of 0% by mass, sample injection amount: 100 μL, column temperature: 40 ° C., detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
¹³ C-NMR analysis was carried out using a nuclear magnetic resonance apparatus (“AVANCE III HD” from Bruker) under the following conditions.
Frequency: 700MHz
Measurement solvent: Deuterated chloroform (containing trimethylsilane)
Paramagnetic relaxation reagent: Tris (2,4-pentanedionato) chromium (III) 30 mg / mL
Sample solution concentration: 10 mg / mL
Resonance frequency: 175 MHz
Detection pulse flip angle: 90 °
Data acquisition time: 0.7078 seconds Delay time: 1.2139 seconds Integration count: 1800 times (measurement time 1 hour 15 minutes)
Measurement temperature: 25 ° C

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (X-1))
To a 1,000 mL round bottom flask, 53.70 g (300 mmol) of methyl 2- (bromomethyl) acrylate, 82.94 g (600 mmol) of K ₂ CO ₃ and 300 mL of N, N-dimethylformamide (DMF) were added as a precursor. Stirring was started at. There, 54 mL (310 mmol) of octanethiol was dripped slowly. After completion of the dropwise addition, the mixture was stirred at room temperature for 5 hours, and then the reaction was stopped with water, followed by extraction with hexane. Thereafter, the organic layer was dried over anhydrous sodium sulfate aqueous solution, the solvent was distilled off, and purified by column chromatography to obtain 65.46 g (yield 89%) of (X-1).

[Synthesis Example 2] (Synthesis of Compound (X-2))
To a 500 mL round bottom flask, 12.70 g (49 mmol) of the compound (X-1) obtained in Synthesis Example 1 was added, 98 mL of a 5% by mass aqueous sodium hydroxide solution and 163 mL of tetrahydrofuran were added, and stirring was started at 60 ° C. After 10 hours, the reaction solution was bathed in ice, and an aqueous hydrochloric acid solution (2N) was slowly added dropwise thereto. After completion of the dropwise addition, extraction was performed with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain 11.71 g (yield 92%) of (X-1 ′). Next, 2.3037 g (10 mmol) of (X-1 ′), 20 mL of dichloromethane (DCM) and 1 drop of DMF were added to a 300 mL round bottom flask, and stirring was started. There, 1.3 mL of oxalic acid dichloride was slowly added dropwise. After 1 hour, another 20 mL of DCM was added, the reaction solution was cooled in an ice bath, 1-ethylcyclopentanol and pyridine were added thereto, and stirring was started. After 2 hours, the reaction was quenched with water and extracted with DCM. The organic layer was dried over anhydrous sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain 2.39 g (yield 73%) of (X-2).

[Synthesis Examples 3 to 11] (Synthesis of Compounds (X-3) to (X-11))
By appropriately selecting a precursor and performing the same operation as in Synthesis Example 1 or 2, compounds represented by the following formulas (X-3) to (X-11) were synthesized.

<Synthesis of [A] polymer and [D] polymer>
The monomers used for the synthesis of [A] polymer and [D] polymer are shown below.

[[A] Synthesis of polymer]
[Synthesis Example 12] (Synthesis of Polymer (A-1))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%) and (M-7) 54.30 g (20 mol%) were added to 250 g of 2-butanone. After dissolution, 2,2′-azobisisobutyronitrile (5 mol% based on the total monomers) as an initiator was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-1) (yield 153 g, yield 77%). Mw of the polymer (A-1) was 6,900, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 31.9 mol%, 48.6 mol% and It was 19.5 mol%.

[Synthesis Example 13] (Synthesis of Polymer (A-2))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%) and (M-7) 54.30 g (20 mol%) were added to 250 g of 2-butanone. In addition, 2,2′-azobisisobutyronitrile as an initiator (1 mol% based on the total monomers) and octanethiol as a chain transfer agent (5 mol based on the total monomers) %) Was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-2) (yield 150 g, yield 75%). Mw of the polymer (A-2) was 6,850, and Mw / Mn was 1.47. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 32.0 mol%, 48.5 mol% and It was 19.5 mol%. It was confirmed by ¹³ C-NMR that a structure derived from octanethiol was introduced at the end of the polymer.

[Synthesis Example 14] (Synthesis of polymer (A-3))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%), (M-7) 54.30 g (20 mol%) was added to 250 g of 2-butanone. Further, 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and compound (X-1) (as a chain transfer agent (X)) The monomer solution was prepared by charging 5 mol% with respect to the monomer. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-3) (yield 153 g, yield 77%). Mw of the polymer (A-3) was 6,900, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 31.9 mol%, 48.6 mol% and It was 19.5 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-1) was introduced at the end of the polymer.

[Synthesis Example 15] (Synthesis of Polymer (A-4))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%) and (M-7) 54.30 g (20 mol%) were added to 250 g of 2-butanone. Further, 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and the compound (X-2) as a chain transfer agent (X) (all units) The monomer solution was prepared by charging 5 mol% with respect to the monomer. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Next, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-4) (yield 154 g, yield 77%). Mw of the polymer (A-4) was 6,900, and Mw / Mn was 1.44. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 32.1 mol%, 48.4 mol% and It was 19.5 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-2) was introduced at the end of the polymer.

[Synthesis Example 16] (Synthesis of polymer (A-5))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%) and (M-7) 54.30 g (20 mol%) were added to 250 g of 2-butanone. Further, 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and compound (X-3) (as a chain transfer agent (X)) The monomer solution was prepared by charging 5 mol% with respect to the monomer. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Next, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-5) (yield 156 g, yield 78%). Mw of the polymer (A-5) was 7,000, and Mw / Mn was 1.49. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 32.1 mol%, 48.5 mol% and It was 19.4 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-3) was introduced at the end of the polymer.

[Synthesis Example 17] (Synthesis of Polymer (A-6))
Compound (M-1) 68.79 g (38 mol%), compound (M-6) 76.91 g (42 mol%) and (M-7) 54.30 g (20 mol%) were added to 250 g of 2-butanone. Further, 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and compound (X-4) (as a chain transfer agent (X)) The monomer solution was prepared by charging 5 mol% with respect to the monomer. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 4 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, 200 g of 2-butanone was added to the polymerization reaction solution, and then poured into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Then, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-6) (yield 153 g, yield 77%). Mw of the polymer (A-6) was 7,000, and Mw / Mn was 1.49. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), (M-6) and (M-7) were 32.1 mol%, 48.5 mol% and It was 19.4 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-4) was introduced at the end of the polymer.

[Synthesis Example 18] (Synthesis of Polymer (A-7))
Compound (M-2) 67.83 g (40 mol%), Compound (M-4) 45.34 g (20 mol%), (M-8) 38.40 g (20 mol%) and (M-10) 48 .43 g (20 mol%) was dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator was added. A monomer solution was prepared. Meanwhile, 200 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 3 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, the white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-7) (yield 162 g, yield 81%). Mw of the polymer (A-7) was 6,700, and Mw / Mn was 1.44. In addition, as a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-2), (M-4), (M-8) and compound (M-10) were 34.9 mol%, respectively. 19.5 mol%, 20.6 mol% and 25.0 mol%.

[Synthesis Example 19] (Synthesis of polymer (A-8))
Compound (M-2) 67.83 g (40 mol%), Compound (M-4) 45.34 g (20 mol%), (M-8) 38.40 g (20 mol%) and (M-10) 48 .43 g (20 mol%) is dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and a chain transfer agent Compound (X-5) (5 mol% with respect to all monomers) as (X) was added to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 3 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-8) (yield 160 g, yield 80%). Mw of the polymer (A-8) was 6,700, and Mw / Mn was 1.43. In addition, as a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-2), (M-4), (M-8) and compound (M-10) were 34.9 mol%, respectively. 19.6 mol%, 20.4 mol% and 25.1 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-5) was introduced at the end of the polymer.

[Synthesis Example 20] (Synthesis of Polymer (A-9))
Compound (M-2) 67.83 g (40 mol%), Compound (M-4) 45.34 g (20 mol%), (M-8) 38.40 g (20 mol%) and (M-10) 48 .43 g (20 mol%) is dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and a chain transfer agent Compound (X-6) (5 mol% with respect to all monomers) as (X) was added to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 3 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Next, the white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-9) (yield 160 g, yield 80%). Mw of the polymer (A-9) was 6,700, and Mw / Mn was 1.43. In addition, as a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-2), (M-4), (M-8) and compound (M-10) were 34.9 mol%, respectively. 19.6 mol%, 20.4 mol% and 25.1 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-6) was introduced at the end of the polymer.

[Synthesis Example 21] (Synthesis of Polymer (A-10))
Compound (M-2) 67.83 g (40 mol%), Compound (M-4) 45.34 g (20 mol%), (M-8) 38.40 g (20 mol%) and (M-10) 48 .43 g (20 mol%) is dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and a chain transfer agent Compound (X-7) (5 mol% with respect to all monomers) as (X) was added to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 3 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-10) (yield 160 g, yield 80%). Mw of the polymer (A-10) was 6,700, and Mw / Mn was 1.43. In addition, as a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-2), (M-4), (M-8) and compound (M-10) were 34.9 mol%, respectively. 19.6 mol%, 20.4 mol% and 25.1 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-7) was introduced at the end of the polymer.

[Synthesis Example 22] (Synthesis of Polymer (A-11))
Compound (M-2) 67.83 g (40 mol%), Compound (M-4) 45.34 g (20 mol%), (M-8) 38.40 g (20 mol%) and (M-10) 48 .43 g (20 mol%) is dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on the total monomers) as an initiator and a chain transfer agent Compound (X-8) (5 mol% with respect to the total monomers) as (X) was added to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours, and after completion of the addition, the mixture was further stirred at 80 ° C. for 3 hours. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 4,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was washed twice with 800 g of methanol and then separated by filtration. Subsequently, this white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-11) (yield 160 g, yield 80%). Mw of the polymer (A-11) was 6,700, and Mw / Mn was 1.43. In addition, as a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-2), (M-4), (M-8) and compound (M-10) were 34.9 mol%, respectively. 19.6 mol%, 20.4 mol% and 25.1 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-8) was introduced at the end of the polymer.

[Synthesis Example 23] (Synthesis of polymer (A-12))
Compound (M-5) 65.34 g (40 mol%), Compound (M-9) 13.25 g (10 mol%), Compound (M-11) 46.99 g (50 mol%), 2 as an initiator , 2′-azobisisobutyronitrile (5 mol% based on the total monomers) and t-dodecyl mercaptan (5 mol% based on the total monomers) as a chain transfer agent were added to propylene glycol monomethyl ether After dissolving in 100 g, the reaction temperature was kept at 70 ° C. in a nitrogen atmosphere and copolymerization was performed for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added again to the above polymer, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-12) was obtained (67.8g, yield 77%). Mw of the polymer (A-12) was 7500, and Mw / Mn was 1.89. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M-5) and (M-9) was 49.7 mol%, 38.3 mol% and 12. It was 0 mol%. It was confirmed by ¹³ C-NMR that a structure derived from t-dodecyl mercaptan was introduced at the end of the polymer.

[Synthesis Example 24] (Synthesis of Polymer (A-13))
Compound (M-5) 65.34 g (40 mol%), Compound (M-9) 13.25 g (10 mol%), Compound (M-11) 46.99 g (50 mol%), 2 as an initiator , 2′-azobisisobutyronitrile (5 mol% based on the total monomers) and compound (X-9) (5 mol% based on the total monomers) as the chain transfer agent (X) After being dissolved in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere and copolymerization was performed for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-13) was obtained (67.8g, yield 77%). Mw of the polymer (A-13) was 7,500, and Mw / Mn was 1.89. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M-5) and (M-9) was 49.8 mol%, 38.2 mol%, and 12. It was 0 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-9) was introduced at the end of the polymer.

[Synthesis Example 25] (Synthesis of Polymer (A-14))
Compound (M-5) 65.34 g (40 mol%), Compound (M-9) 13.25 g (10 mol%), Compound (M-11) 46.99 g (50 mol%), 2 as an initiator , 2′-azobisisobutyronitrile (5 mol% based on the total monomers) and compound (X-10) (5 mol% based on the total monomers) as the chain transfer agent (X) After being dissolved in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere and copolymerization was performed for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-14) was obtained (67.8g, yield 77%). Mw of the polymer (A-14) was 7,500, and Mw / Mn was 1.89. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M-5) and (M-9) was 49.6 mol%, 38.1 mol%, and 12. It was 3 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-10) was introduced at the end of the polymer.

[Synthesis Example 26] (Synthesis of Polymer (A-15))
Compound (M-5) 65.34 g (40 mol%), Compound (M-9) 13.25 g (10 mol%), Compound (M-11) 46.99 g (50 mol%), 2 as an initiator , 2′-azobisisobutyronitrile (5 mol% based on the total monomers) and compound (X-11) (5 mol% based on the total monomers) as the chain transfer agent (X) After being dissolved in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere and copolymerization was performed for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-15) was obtained (67.8g, yield 77%). Mw of the polymer (A-15) was 7,500, and Mw / Mn was 1.89. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M-5) and (M-9) was 49.6 mol%, 38.0 mol%, and 12. It was 4 mol%. It was confirmed by ¹³ C-NMR that the structure derived from the compound (X-11) was introduced at the end of the polymer.

[[D] Synthesis of polymer]
Compound (M-3) 79.9 g (70 mol%) and compound (M-12) 20.91 g (30 mol%) were dissolved in 100 g of 2-butanone, and dimethyl 2,2′- as an initiator was dissolved. Azobisisobutyrate (7 mol% based on the total monomers) was dissolved to prepare a monomer solution. Next, a 1,000 mL three-necked flask containing 100 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. did. 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 solution was cooled with water and cooled to 30 ° C. or lower. After transferring the reaction solution to a 2,000 mL separatory funnel, the polymerization solution was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed. Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution containing the polymer (D-1) as a solid content (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 ratio of each structural unit derived from (M-3) and (M-12) was 71.1 mol% and 28.9 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [C] acid diffusion controller, [E] solvent, and [F] uneven distribution accelerator used for the preparation of the radiation sensitive resin composition are shown below.

[[B] acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate B-2: Triphenylsulfonium norbornane sultone-2-yloxy Carbonyl difluoromethanesulfonate B-3: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B-4: Triphenylsulfonium adamantane- 1-yloxycarbonyldifluoromethanesulfonate

[[C] acid diffusion controller]
Each structural formula is shown below.
C-1: triphenylsulfonium 3-oxo-3H-benzo [d] isothiazol-2-ide 1,1-dioxide C-2: triphenylsulfonium 2-hydroxybenzoate C-3: cyclohexylphenyldiphenylsulfonium 10- Camphorsulfonate C-4: Triphenylsulfonium 1,4-bis (cyclohexyloxy) -1,4-dioxobutane-1-sulfonate C-5: t-butylpyrrolidine-1-carboxylate C-6: 2-isopropylaniline C -7: Tri-n-octylamine

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

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

[Preparation of radiation-sensitive resin composition for ArF exposure]
[Example 1]
[A] 100 parts by mass of (A-3) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 3 as an acid diffusion controller 0.5 parts by mass, (E-1) 2,240 parts by mass as a solvent and (E-2) 960 parts by mass, and [F] 100 parts by mass of (F-1) as an uneven distribution promoter And the radiation sensitive resin composition (J-1) was prepared by filtering the obtained mixture with the membrane filter of the hole diameter of 0.2 micrometer.

[Examples 2 to 8 and Comparative Examples 1 to 6]
Except having used each component of the kind and content shown in following Table 1, it operated similarly to Example 1 and the radiation sensitive resin compositions (J-2)-(J-8) and (CJ-1). ) To (CJ-6) were prepared.

<Formation of resist pattern (1)> (Alkali development)
A 12-inch silicon wafer surface was coated with a composition for forming a lower antireflection film (“ARC66” from Brewer Science) using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron), and then 205 ° C. Was heated for 60 seconds to form a lower antireflection film having an average thickness of 105 nm. On the lower antireflection film, each of the prepared radiation sensitive resin compositions was applied using the spin coater, and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average thickness of 90 nm. Next, this resist film was subjected to 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). , Exposed through a 40 nm line and space (1L1S) mask pattern. After the exposure, PEB was performed at 90 ° C. for 60 seconds. Thereafter, alkali development was performed using a 2.38% by mass TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern. When this resist pattern is formed, the line width formed through a one-to-one line and space mask having a target dimension of 40 nm is defined as an optimum exposure amount. did.

<Formation of resist pattern (2)> (Organic solvent development)
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Evaluation>
About the formed resist pattern, each radiation sensitive resin composition was evaluated by measuring according to the following method. A scanning electron microscope (Hitachi High-Technologies “CG-4100”) was used for measuring the resist pattern.

[CDU performance]
The 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 CDU performance. The CDU performance indicates that the smaller the value, the better. The CDU performance can be judged as “good” when it is 3.00 nm or less, and “bad” when it exceeds 3.00 nm.

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure dose was measured, and the measurement result was defined as resolution. The smaller the measured value, the better the resolution. When the resolution is 35 nm or less, it can be judged as “good”, and when it exceeds 35 nm, it can be judged as “bad”.

[Preparation of radiation-sensitive resin composition for electron beam exposure]
[Example 9]
[A] 100 parts by mass of (A-13) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] (C-1) 3.6 as an acid diffusion controller (E-1) 4,280 parts by mass and (E-2) 1,830 parts by mass as [E] solvent are mixed, and the mixture is filtered through a membrane filter having a pore size of 0.2 μm to provide a radiation sensitive resin. A composition (J-9) was prepared.

[Examples 10 to 11 and Comparative Examples 7 to 9]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 9 except that the components of the types and blending amounts shown in Table 3 below were used.

<Formation of resist pattern (3)> (Alkali development)
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each radiation-sensitive resin composition described in Table X was applied, and PB was performed at 90 ° C. for 60 seconds. . Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average thickness of 50 nm. Next, the resist film was irradiated with an electron beam using a simple electron beam drawing apparatus (model “HL800D”, output from Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm 2). After irradiation, PEB was performed at 120 ° C. for 60 seconds. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern.

<Formation of resist pattern (4)> (Organic solvent development)
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Evaluation>
Evaluation similar to Examples 1-8 was implemented about the resist pattern formed using each said radiation sensitive resin composition. The results are shown in Table 4 below. About the radiation sensitive resin composition for electron beam exposure, when CDU performance is 5.00 nm or less, it can be evaluated as "good", and when exceeding 5.00 nm, it is evaluated as "bad". When the resolution is 35 nm or less, it can be evaluated as “good”, and when it exceeds 35 nm, it can be evaluated as “bad”.

  From the results of Table 2 and Table 4, the radiation-sensitive resin compositions of the examples are excellent in CDU performance and resolution both in the case of ArF exposure and electron beam exposure, and in the case of alkali development and organic solvent development. I understand. In addition, it is known that electron beam exposure and EUV exposure tend to have the same tendency, and according to the radiation-sensitive resin compositions of the examples, it is presumed that LWR performance and the like are excellent even in the case of EUV exposure. .

  According to the radiation sensitive resin composition and resist pattern forming method of the present invention, various groups can be introduced into the polymer. As a result, the radiation-sensitive resin composition containing such a polymer can form resist patterns excellent in various lithography performances. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (9)

A polymer having a structural unit containing an acid-dissociable group, and a radiation-sensitive resin composition containing a radiation-sensitive acid generator,
A radiation-sensitive resin composition, wherein the polymer is obtained by radical polymerization using a chain transfer agent represented by the following formula (1).

(In Formula (1), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. A is —CH ₂ —, an oxygen atom, —OCH ₂ — or —NR ² —. R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, R ¹ and R ² are combined with each other, together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. A ring structure having 3 to 10 ring members may be formed, and when A is —CH ₂ —, X is —R ³ , —OR ³ , —SR ³ , —SiR ³ R ⁴ R ⁵ , —SnR ^3. R ⁴ R ⁵ , —SOR ³ , —SO ₂ R ^3, or —PO (OR ³ ) (OR ⁴ ), wherein R ³ , R ^4, and R ⁵ each independently have a carbon atom bond. when a monovalent organic group having 1 to 20 carbon atoms .A is an oxygen atom, X is -R ³ .A is -OCH ₂ - -NR ² is - case, X is -OR ³ .Z is = ^CR 6 ^{R 7} or a sulfur atom in which .R ⁶ and ^{R 7} are each independently a hydrogen atom or 1 to carbon atoms 20 monovalent organic groups.) A polymer having a structural unit containing an acid-dissociable group, and a radiation-sensitive resin composition containing a radiation-sensitive acid generator,
A radiation-sensitive resin composition, wherein the polymer is bonded to one end of the main chain and has a group represented by the following formula (2).

(In Formula (2), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. A ¹ is ═CH ₂ , an oxygen atom, or ═NR ^2. R ² is hydrogen. An atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, R ¹ and R ² are combined with each other and have 3 to 10 ring members together with the carbon atom to which R ¹ is bonded and the nitrogen atom to which R ² is bonded. A ring structure may be formed, and Z ′ is —CR ⁶ R ⁷ — or a sulfur atom, and R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * ¹ represents a site bonded to one end of the main chain of the polymer.) The radiation sensitive resin composition of Claim 2 which has further couple | bonded with the other terminal of a principal chain and represented by following formula (3).

(In the formula (3), ^{X 1} is the formula (2) When the ^{A 1} is = CH ₂ ^{in, -R 3, -SiR 3 R 4} R 5, -SnR 3 R 4 R 5, -SOR 3, —SO ₂ R ³ or —PO (OR ³ ) (OR ⁴ ) R ³ , R ^4, and R ⁵ are each independently a monovalent monovalent group having 1 to 20 carbon atoms in which the carbon atom has a bond. X ¹ is —R ³ when A ¹ in the above formula (2) is an oxygen atom, and X ¹ is —OR when A ¹ in the above formula (2) is ═NR ^{2. 3.} * ² represents a site bonded to the other end of the main chain of the polymer. A polymer having a structural unit containing an acid-dissociable group, and a radiation-sensitive resin composition containing a radiation-sensitive acid generator,
A radiation-sensitive resin composition, wherein the polymer is bonded to one end of the main chain and has a group represented by the following formula (4).

(In Formula (4), R ¹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Z ′ is —CR ⁶ R ⁷ — or a sulfur atom. R ⁶ and R ⁷ are And each independently represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * ³ represents a site bonded to one end of the main chain of the polymer.) The radiation sensitive resin composition of Claim 4 which has further couple | bonded with the other terminal of a principal chain and represented by following formula (5).

(In the formula (5), ^{X 2} is .R ³ is -OR ³ or -SR ³ is a monovalent organic group having 1 to 20 carbon atoms in which carbon atoms having a bond. ^{* 4,} (The site | part couple | bonded with the other terminal of the principal chain of the said polymer is shown.) R ¹ is a hydrogen atom, —R ⁸ , —CN, —CONHR ⁸ , —OCONHR ⁸ , —OR ⁸ , —OCOR ⁸ , —COOR ⁸ , —CH ₂ OR ⁸ , —CH ₂ OCOR ⁸ or —CH ₂ COOR. ^The radiation sensitive resin composition according to claim 1, wherein R ⁸ is a monovalent hydrocarbon group having 1 to 18 carbon atoms. Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
The resist pattern formation method which forms the said resist film with the radiation sensitive resin composition of any one of Claims 1-6.   The resist pattern forming method according to claim 7, wherein in the developing step, a positive resist pattern is formed by development with an alkaline solution.   The resist pattern forming method according to claim 7, wherein, in the developing step, a negative resist pattern is formed by development with an organic solvent-containing liquid.