JP6648452B2 - Radiation-sensitive resin composition and method for forming resist pattern - Google Patents

Description

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

  The radiation-sensitive composition used for fine processing by lithography is exposed to light by irradiation with far ultraviolet rays such as ArF excimer laser light and KrF excimer laser light, electromagnetic waves such as extreme ultraviolet (EUV), and charged particle beams such as electron beams. An acid is generated, and a chemical reaction using the acid as a catalyst causes a difference in the dissolution rate of the exposed part and the unexposed part in the developing solution, thereby forming a pattern on the substrate.

  Such a radiation-sensitive composition is excellent in Line Width Roughness (LWR) performance and rectangular shape of the cross-sectional shape of a resist pattern, and is capable of obtaining a highly accurate pattern at a high yield with the miniaturization of processing technology. Desired. In response to such demands, the types and molecular structures of the polymer, acid generator, and other components used in the radiation-sensitive composition have been studied, and their combinations have also been studied in detail (Japanese Patent Laid-Open No. 11-1999). 125907, JP-A-8-146610 and JP-A-2000-298347).

  However, at present, when the resist pattern is miniaturized to a line width of 45 nm or less, the required level of the performance is further increased, and it is difficult for the conventional radiation-sensitive resin composition to meet these requirements. . Further, in order to further enhance the lithography performance described above, it is also required that the resist film be small in shrinkage during post-exposure bake (Post Exposure Bake (PEB)) and be excellent in film shrinkage suppression.

JP-A-11-125907 JP-A-8-146610 JP 2000-298347 A

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a radiation-sensitive resin composition excellent in LWR performance, rectangular cross-sectional shape, and film shrinkage suppressing property, and a resist pattern using the same. It is to provide a forming method.

（式（１）中、Ａは、−ＣＨ_２−、酸素原子又は−Ｎ（Ｒ^１）−である。Ｒ^１は、水素原子又は炭素数１〜２０の１価の炭化水素基である。Ｌは、炭素数１〜３０の２価の有機基である。Ｒ^１及びＬは、互いに合わせられ、Ｒ^１に結合する窒素原子及びＺに結合する炭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^２Ｒ^３又は硫黄原子である。Ｒ^２及びＲ^３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-mentioned problems is directed to a polymer having a structural unit containing an acid dissociable group (hereinafter, also referred to as “[A] polymer”), and a radiation-sensitive composition containing a radiation-sensitive acid generator. Resin (hereinafter also referred to as “radiation-sensitive resin composition (I)”), wherein the polymer (A) is a compound represented by the following formula (1) (hereinafter, “compound (X) )), Which is obtained by radical polymerization in the presence of)).

(In the formula (1), A is —CH ₂ —, an oxygen atom, or —N (R ¹ ) —. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. L is a divalent organic group having 1 to 30 carbon atoms, and R ¹ and L are combined with each other to form a ring structure having 3 to 10 ring members together with a nitrogen atom bonded to R ¹ and a carbon atom bonded to Z. Z is ＝ CR ² R ³ or a sulfur atom, and R ² and R ³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. )

（式（２）中、Ａ^１は、＝ＣＨ_２、酸素原子又は＝ＮＲ^１である。Ｒ^１は、水素原子又は炭素数１〜２０の１価の炭化水素基である。Ｌは、炭素数１〜３０の２価の有機基である。Ｒ^１及びＬは、互いに合わせられ、Ｒ^１に結合する窒素原子及びこの窒素原子に結合する炭素原子と共に環員数３〜１０の環構造を形成してもよい。Ｚ^１は、−ＣＲ^２Ｒ^３−又は硫黄原子である。Ｒ^２及びＲ^３、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。） Another invention made to solve the above-mentioned problem is a polymer having a first structural unit containing an acid-dissociable group and a second structural unit represented by the following formula (2) (hereinafter referred to as “[A- 1] polymer)) and a radiation-sensitive resin composition containing a radiation-sensitive acid generator (hereinafter, also referred to as “radiation-sensitive resin composition (II)”).

(In formula (2), ^{A 1} is = CH _2, .R ¹ is an oxygen atom or = NR ¹ is a is .L monovalent hydrocarbon group hydrogen atom or a carbon number of 1 to 20, carbon R ¹ and L are combined with each other to form a ring structure having 3 to 10 ring members together with a nitrogen atom bonded to R ¹ and a carbon atom bonded to the nitrogen atom. good .Z ¹ also has, ^-CR 2 ^{R 3} - or a sulfur atom in which .R ² and ^{R 3,} each independently, a monovalent organic group hydrogen atom or a C 1-20).

  Another invention made to solve the above problem includes a step of forming a resist film, a step of exposing the resist film, and a step of developing the exposed resist film. This is a method for forming a resist pattern using a resin composition.

  Here, the “hydrocarbon group” refers to a group containing a chain hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. This “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 is composed of only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. "Alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic structure as a ring structure and not containing an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Contains both hydrocarbon groups. However, it is not necessary to be composed only of an 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. “Organic group” refers to a group having at least one carbon atom. "Number of ring members" refers to the number of atoms constituting a ring of an aromatic ring structure, an aromatic heterocyclic structure, an alicyclic structure, and an aliphatic heterocyclic structure. Means the number of atoms to perform.

  According to the radiation-sensitive resin composition and the method of forming a resist pattern of the present invention, a resist pattern having excellent LWR performance, rectangular cross-sectional shape, and film shrinkage-suppressing properties can be formed. Therefore, they can be suitably used for the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

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

<[A] polymer>
[A] The polymer has a structural unit containing an acid dissociable group (hereinafter, also referred to as “structural unit (I)”), and is a polymer obtained by radical polymerization in the presence of compound (X). . That is, the polymer [A] is a polymer having a structural unit (I) and a structural unit derived from the compound (X) (hereinafter, also referred to as “structural unit (II)”). The radiation-sensitive resin composition (I) is a resist excellent in LWR performance, rectangular cross-sectional shape and film shrinkage suppressing property because the polymer [A] is obtained by radical polymerization in the presence of the compound (X). A pattern can be formed. Although the reason why the radiation-sensitive resin composition (I) has the above-described structure to achieve the above-mentioned effects is not necessarily clear, it can be inferred, for example, as follows. That is, the radical polymerization in the presence of the compound (X) introduces a structure represented by -C (= A ¹ ) derived from the compound (X) into the main chain of the polymer [A]. Due to the steric factor of this structure, the polymer [A] has an expanded spatial extent. In addition, since the structural unit derived from the compound (X) is introduced into the main chain of the polymer [A], the structural unit having one or more of the above-described characteristics is obtained by radical polymerization in the presence of the compound (X). Is introduced into the polymer [A]. As a result, the diffusion length of the acid generated from the acid generator [B] in the resist film becomes appropriately short, and the LWR performance and the rectangularity of the cross-sectional shape become excellent. Further, it is considered that the evaporation of the low-molecular compound at the time of PEB is suppressed, and the film shrinkage suppressing property is improved.

  [A] The polymer is a structural unit containing at least one of a lactone structure, a cyclic carbonate structure and a sultone structure in addition to the structural unit (I) and the structural unit (II) (hereinafter referred to as “structural unit (III) ) And a structural unit containing a phenolic hydroxyl group (hereinafter, also referred to as “structural unit (IV)”), and may have other structural units other than the above structural units.

  Hereinafter, the compound (X) and the structural units (I) to (IV) will be described in order.

<Compound (X)>
Compound (X) is a compound represented by the following formula (1). Compound (X) is a radical polymerizable compound. Compound (X) gives structural unit (II) to polymer [A] by radical polymerization in the presence of compound (X). Therefore, the structural unit derived from the compound (X) can be introduced into the polymer [A], and the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property can be improved.

In the formula (1), A is, -CH ₂ -, an oxygen atom or -N ^{(R 1)} - is. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. L is a divalent organic group having 1 to 30 carbon atoms. R ¹ and L may be combined with each other to form a ring structure having 3 to 10 ring members together with the nitrogen atom bonded to R ¹ and the carbon atom bonded to Z. Z is ＝ CR ² R ³ or a sulfur atom. R ² and R ³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^1, for example, a monovalent chain-like hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic having 3 to 20 carbon atoms Examples thereof include a hydrocarbon group 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 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, an alkyl group such as a t-butyl group;
Alkenyl groups such as an ethenyl group, a propenyl group and a butenyl group;
Alkynyl groups such as an ethynyl group, a propynyl group and a butynyl group are exemplified.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, methylcyclopentyl group, ethylcyclopentyl group, cyclohexyl group, and cyclooctyl group. An alkyl group;
Monocyclic cycloalkenyl groups such as cyclobutenyl group, cyclopentenyl group and cyclohexenyl group;
Polycyclic cycloalkyl groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group and a tetracyclododecyl group;
Examples include 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;
And aralkyl groups such as benzyl group, phenethyl group, cumyl group and naphthylmethyl group.

As the above A, —CH ₂ — and an oxygen atom are preferable from the viewpoint of easiness of radical polymerization.

  As the divalent organic group having 1 to 30 carbon atoms represented by L, for example, a divalent hydrocarbon group having 1 to 30 carbon atoms, a carbon-carbon end of this hydrocarbon group or a terminal at a bond side Examples include the group (a) containing a divalent hetero atom-containing group, and a group in which part or all of the hydrogen atoms contained in the hydrocarbon group and the group (a) are substituted with a monovalent hetero atom-containing group.

  Examples of the divalent hydrocarbon group having 1 to 30 carbon atoms include a divalent chain hydrocarbon group having 1 to 30 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 30 carbon atoms, and a carbon number of 3 to 30 carbon atoms. And 6 to 30 divalent aromatic hydrocarbon groups.

Examples of the divalent chain hydrocarbon group having 1 to 30 carbon atoms include methanediyl, ethanediyl, n-propanediyl, i-propanediyl, n-butanediyl, i-butanediyl, and sec-butanediyl. Groups, alkanediyl groups such as t-butanediyl group;
Alkenediyl groups such as an ethenediyl group, a propenediyl group and a butenediyl group;
Examples include alkynediyl groups such as an ethynediyl group, a propyndiyl group, and a butyndiyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 30 carbon atoms include a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, a methylcyclopentanediyl group, an ethylcyclopentanediyl group, a cyclohexanediyl group, A monocyclic cycloalkanediyl group such as a cyclooctanediyl group;
A monocyclic cycloalkenediyl group such as a cyclobutenediyl group, a cyclopentenediyl group, a cyclohexenediyl group;
Polycyclic cycloalkanediyl groups such as a norbornanediyl group, an adamantanediyl group, a tricyclodecanediyl group, and a tetracyclododecanediyl group;
And polycyclic cycloalkenediyl groups such as a norbornenediyl group, a tricyclodecenediyl group, and a tetracyclododecenediyl group.

Examples of the divalent aromatic hydrocarbon group having 6 to 30 carbon atoms include an arenediyl group such as a benzenediyl group, a toluenediyl group, a xylenediyl group, and a naphthalenediyl group;
Arenediylalkanediyl groups such as benzenediylmethanediyl group, benzenediylethanediyl group, naphthalenediyl sec-butanediyl group;
And arylalkanediyl groups such as phenylmethanediyl group, diphenylmethanediyl group, and naphthylmethanediyl group.

Examples of the divalent hetero atom-containing group include -CH (CN)-, -O-, -C (O)-, -S-, -C (S)-, -S (O) ₂ -,-. ^{N (R ') -, -} Sn (R 4) (R 5) -, - Si (R 4) (R 5) -, - P (O) (oR 4) -, two or more of these Examples include a combined group. R ′ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal on the joint side. R ⁴ and R ⁵ are each independently a terminal hydroxy group or a bond side is a monovalent organic group having 1 to 20 carbon atoms having a carbon atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal of the bond represented by R ′, R ⁴ and R ⁵ include those exemplified as the divalent organic group of L above. And a group having 1 to 20 carbon atoms having a carbon atom at the terminal on the bond side among the groups obtained by adding one hydrogen atom to the above.

As R ⁴ and R ⁵ , a hydroxy group and a chain hydrocarbon group are preferred, a hydroxy group and an alkyl group are more preferred, and a hydroxy group and a methyl group are still more preferred.

Divalent carbons of the hydrocarbon groups of 1 to 30 carbon atoms - Examples of the group (a) containing a divalent heteroatom-containing group at the terminal carbon-carbon or a bond side, for example, -CH (CN) -R ^{6 '' -, - C (O} ) -NH-R 6 '' -, - O-C (O) -NH-R 6 '' -, - O-R 6 '' -, - C (O) -R ^{6 '' -, - S-} R 6 '' -, - C (S) -R 6 '' -, - S (O) 2 -R 6 '' -, - N (R ') - R 6'' -, - O-C (O ) -R 6 '' -, - C (O) -O-R 6 '' -, - CH 2 -O-R 6 '' -, - CH 2 -O-C ( _{^{O) -R 6 '' -,}} - CH 2 C (O) -O-R 6 '' -, - Sn (R 4) (R 5) -R 6 '' -, - Si (R 4) (R ⁵ ) —R ^{6 ″} —, —P (O) (R ⁴ ) —O—R ^{6 ″} — and the like. R ^{6 ″} is a divalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal on the divalent hetero atom-containing group side.

Examples of the divalent organic group having 1 to 20 carbon atoms having a carbon atom at the terminal of the divalent hetero atom-containing group represented by R ^{6 ″} include those exemplified as the organic group of L above. Examples thereof include a group having 1 to 20 carbon atoms having a carbon atom at the terminal on the divalent hetero atom-containing group side.

^'The, LWR performance, from the viewpoint of improving the rectangle and the film shrinkage suppression of cross-* ^2' the ^{R 6 '-R 7 -, *} 2' -CH (CN) -R 7 -, * ^{2 '-C (O) -NH-} R 7 -, * 2' -O-C (O) -NH-R 7 -, * 2 '-O-R 7 -, * 2' -O-C (O ^{) -R 7 -, * 2 '} -R 7 -C (O) -, * 2' -C (O) -O-R 7 -, * 2 '-CH 2 -O-R 7 -, * 2' _{-CH 2 -O-C (O)} -R 7 - and _{^{* 2 '-CH 2 -C (O}} ) -O-R 7 - are ^{preferred, * 2' -CH (CN)} -R 7 -, * 2 ^{'-R 7} -C (O) - and ^{* 2' -C (O) -O} -R 7 - is more preferable. R ⁷ is a divalent hydrocarbon group having 1 to 18 carbon atoms. * ^{2 ′} indicates a site that binds to the divalent hetero atom-containing group.

Examples of the divalent hydrocarbon group having 1 to 18 carbon atoms represented by R ⁷ include a hydrocarbon group having 1 to 18 carbon atoms among those exemplified as the hydrocarbon group of L above.

R ⁷ is preferably an alkanediyl group, a cycloalkanediyl group, an arenediylalkanediyl group or a diarylalkanediyl group, and is preferably a methanediyl group, a 2,2-propanediyl group, a 2,2-hexanediyl group, a 2,2 -(7,7-Dimethyl) norbornanediyl, diphenylmethanediyl, naphthalenediylpropanediyl and benzenediylmethanediyl are more preferred.

Further, as R ^{6 ″} , an electron withdrawing group is preferable from the viewpoint of easiness of radical polymerization. Here, the term "electron-withdrawing group" refers to a group having a tendency to attract electrons, for example, a group having a tendency to attract electrons from an atom located in a position close to the electron-withdrawing group in a molecule. .

The electronic The withdrawing group, for example the above-mentioned benzene-diyl ^{group, -CH (CN) -R 7 -} , - C (O) -NH-R 7 -, - O-C (O) -NH-R 7 ^{-, - O-R 7 -} , - O-C (O) -R 7 -, - C (O) -O-R 7 -, - CH 2 -O-R 7 -, - CH 2 -O-C (O) —R ⁷ —, —CH ₂ —C (O) —O—R ⁷ — and, besides these, for example, —S (O) ₂ —O—R ⁷ — and the like.

  Examples of the monovalent hetero atom-containing 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, a cyano group, an amino group, a sulfanyl group (—SH), and the like. .

When A is —CH ₂ —, as L, * ^1- Sn (R ⁴ ) (R ⁵ ) -R ⁶ is used as L from the viewpoint of further improving LWR performance, rectangularity in cross-sectional shape, and suppressing film shrinkage. ^{'' -, * 1 -Si (} R 4) (R 5) -R 6 '' -, * 1 -P (O) (R 4) -O-R 6 -, * 1 -S (O) 2 - R ^{6 ″} -, * ¹ -SR ^{6 ″} -and a divalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal on the A side are preferable, and are dialkylstannandiyl-cyano-alkanediyl. Group, dihydroxysilanediyldiarylalkanediyloxycarbonyl group, hydroxyoxyphosphanediyloxyalkanediyloxycarbonyl group, thio-alkanediyloxycarbonyl group, thio-cycloalkanediyloxycarbonyl group and arenediylal And a dimethylstannandiyl-cyano-ethanediyl group, a dihydroxysilanediyldiphenylmethanediyloxycarbonyl group, a hydroxyoxyphosphanediyloxy-2,2-hexanediyloxycarbonyl group, and a thio-2,2-propanediyl group. An oxycarbonyl group, a thio-2,2- (7,7-dimethyl) norbornanediyloxycarbonyl group and a naphthalenediylpropanediyl group are more preferred. * ¹ indicates a site binding to the above A. In this case, R ^{6 ″} is a divalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal on the A side (hereinafter, also referred to as “R ⁶ ”). In addition, * ^{2 ′} of R ⁶ ″ indicates a site bonded to the carbon atom bonded to Z (hereinafter, also referred to as “* ² ”).

When A is an oxygen atom, L is preferably * ^1- R ^6- , more preferably an areendiylalkanediyl group, from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property. And a benzenediylmethanediyl group are more preferred.

When A is -N (R ¹ )-, the L is * ^1- OR ⁶ -from the viewpoint of further improving LWR performance, rectangularity of the cross-sectional shape, and suppressing film shrinkage. Preferably, ¹ and R ⁶ are combined with each other to form a ring structure having 3 to 10 ring members together with the nitrogen atom bonded to R ¹ and the carbon atom bonded to this nitrogen atom. In this case, it is preferable that R ¹ and R ⁶ are combined with each other to form a ring structure having 3 to 10 ring members together with the nitrogen atom bonded to R ¹ and the oxygen atom bonded to R ⁶ .

Examples of the ring structure having 3 to 10 ring members formed by combining the above R ¹ and R ⁶ together with a nitrogen atom bonded to R ¹ and a carbon atom bonded to the nitrogen atom include, for example, a ring structure having 3 to 20 ring members. And a nitrogen-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, and aza Azacycloalkane structures such as cyclooctane structure and azacyclodecane structure;
Azaoxacycloalkane structures such as an azaoxacyclobutane structure, an azaoxacyclohexane structure (including a morpholine structure), and an azaoxacyclooctane structure;
Azacyclobutene structures, azacyclopentene structures, azacyclohexene structures, azacycloheptene structures, azacyclooctene structures, azacyclodecene structures and other azacycloalkene structures;
An azacycloalkadiene structure such as an azacyclohexadiene structure, an azacycloheptadiene structure, an azacyclooctadiene structure, and an azacyclodecadiene structure is exemplified.

The above R ¹ and R ⁶ are combined with each other, and as a ring structure having 3 to 10 ring members formed together with a nitrogen atom bonded to R ¹ and a carbon atom bonded to this nitrogen atom, the LWR performance, the rectangularity of the cross-sectional shape, An azacycloalkane structure is preferred, and an azacycloheptane structure is more preferred, from the viewpoint of further improving the film shrinkage suppressing property.

Examples of the ring structure having 3 to 10 ring members formed by combining R ¹ and R ⁶ with each other and forming a nitrogen atom bonded to R ¹ and an oxygen atom bonded to R ⁶ include a nitrogen-containing ring having 3 to 20 ring members. Examples thereof include an oxygen-containing aliphatic heterocyclic structure.

Examples of the nitrogen-containing oxygen-containing aliphatic heterocyclic structure having 3 to 20 ring members include an azaoxacycloalkane structure such as an azaoxacyclobutane structure, an azaoxacyclohexane structure (including a morpholine structure), and an azaoxacyclooctane structure;
Azaoxacarbonylcycloalkane structures such as an azaoxacarbonylcyclobutane structure, an azaoxacarbonylcyclohexane structure and an azaoxacarbonylcyclooctane structure;
An azaoxacycloalkene structure such as an azaoxacyclobutene structure, an azaoxacyclopentene structure, an azaoxacyclohexene structure, an azaoxacycloheptene structure, an azaoxacyclooctene structure, and an azaoxacyclodecene structure;
Azaoxacarbonylcycloalkene structures such as an azaoxacarbonylcyclobutene structure, an azaoxacarbonylcyclopentene structure, an azaoxacarbonylcyclohexene structure, an azaoxacarbonylcycloheptene structure, an azaoxacarbonylcyclooctene structure, and an azaoxacarbonylcyclodecene structure;
Azaoxacycloalkadiene structures such as azaoxacyclohexadiene structure, azaoxacycloheptadiene structure, azaoxacyclooctadiene structure, and azaoxacyclodecadiene structure;
Examples include an azaoxacarbonylcyclohexadiene structure, an azaoxacarbonylcycloheptadiene structure, an azaoxacarbonylcyclooctadiene structure, and an azaoxacarbonylcycloalkadiene structure such as an azaoxacarbonylcyclodecadiene structure.

The above R ¹ and R ⁶ are combined with each other, and the ring structure having 3 to 10 ring members formed together with the nitrogen atom bonded to R ¹ and the oxygen atom bonded to R ⁶ has LWR performance, rectangularity in cross-sectional shape, and From the viewpoint of further improving the film shrinkage suppressing property, an azaoxacarbonylcycloalkane structure is preferable, and an azaoxacarbonylcycloheptane structure is more preferable.

R ² and R ³ are preferably hydrogen atoms from the viewpoint of easiness of radical polymerization.

  Examples of the compound (X) include compounds represented by the following formulas (1-1) to (1-14) (hereinafter, also referred to as “compounds (X-1) to (X-14)”). .

  Among these, compounds (X-1) to (X-8) are preferable from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the property of suppressing film shrinkage.

<Structural unit (I)>
[A] The polymer has a 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) Unit (hereinafter, also referred to as “structural unit (I-2)”) and the like. 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. ^RA2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^A3 and R ^A4 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or 3 to 20 ring members formed by combining these groups together with a carbon atom bonded thereto. Represents an alicyclic structure of

In the formula (a-2), ^RA5 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. ^RA6 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. ^RA7 and ^RA8 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 or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerizability of the monomer giving 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, a monovalent linear carbon group 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 a methyl group, an ethyl group, and an n-propyl group. And alkyl groups such as i-propyl group;
Alkenyl groups such as an ethenyl group, a propenyl group and a butenyl group;
Alkynyl groups such as an ethynyl group, a propynyl group and a butynyl group are exemplified.

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 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 or a cyclooctenyl group;
Polycyclic cycloalkyl groups such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a 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 a monocyclic ring such as a cyclopentyl group and a cyclohexyl group. A cycloalkyl group;
A monocyclic cycloalkenyl group such as a cyclopentenyl group or a cyclohexenyl group;
Polycyclic cycloalkyl groups such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a 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 phenyl, tolyl, xylyl, and naphthyl An aryl group such as a group or an anthryl group;
And aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group and anthrylmethyl group.

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

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

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

As R ^A5 , a hydrogen atom and a methyl group are preferable, and a hydrogen atom is more preferable, from the viewpoint of copolymerizability of a monomer giving the structural unit (I).

^RA6 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 having an oxygen atom between carbon and carbon.

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

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

  As the structural unit (I-1), for example, structural units represented by the following formulas (a-1-a) to (a-1-d) (hereinafter, “structural units (I-1-a) to (I-a) -1-d))).

  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 above formulas (a-1-a) to (a-1-d), R ^{A1 to} R ^A4 have the same meaning as in the above formula (a-1). n _a is an integer of 1 to 4. In the formula ^(a-2-a), R A5 ~R A8 is as defined in 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 a structural unit represented by the following formula.

In the above ^{formulas, R A1} is as defined in 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, ^RA5 has the same ^{meaning as} in the above formula (a-2).

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

  [A] The lower limit of the content of the structural unit (I) with respect to all structural units constituting the polymer is preferably 10 mol%, more preferably 20 mol%, further preferably 25 mol%, and particularly preferably 30 mol%. preferable. On the other hand, the upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, further preferably 65 mol%, and particularly preferably 60 mol%. When the content is in the above range, the dissolution contrast of the exposed part and the unexposed part of the radiation-sensitive resin composition (I) in the developing solution can be sufficiently ensured. The rectangularity of the shape and the property of suppressing film shrinkage are further improved.

<Structural unit (II)>
The structural unit (II) is a structural unit introduced into the polymer [A] by radical polymerization in the presence of the compound (X), and is a structural unit derived from the compound (X). The structural unit (II) is a structural unit represented by the following formula (2).

In the above formula (2), A ¹ is ＝ CH ₂ , an oxygen atom or ＮＲNR ¹ . R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. L is a divalent organic group having 1 to 30 carbon atoms. R ¹ and L are aligned with each other, the ring structure of ring members 3-10 may be formed as well as attached to the nitrogen atom and the nitrogen atom bound to R ^1. Z ¹ is —CR ² R ³ — or a sulfur atom. R ² and R ³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.

A ¹ in the above formula (2) is derived from A in the above formula (1). L in the above formula (2) is derived from L in the above formula (1). Z ¹ in the above formula (2) is derived from Z in the above formula (1).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹ in A ¹ in the formula (2), for example exemplified as the hydrocarbon group of R ¹ in A in the above formula (1) Examples include the same groups as the groups.

As A ¹ in the above formula (2), ＣＨCH ₂ and an oxygen atom are preferable from the viewpoint of easiness of radical polymerization.

  Examples of the divalent organic group having 1 to 30 carbon atoms represented by L in the above formula (2) include the same groups as the groups exemplified as the organic group for L in the above formula (1). .

When A ¹ in the above formula (2) is = CH ₂ , the above L is -Sn (R ⁴ ) (R ⁵ ) from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property. ^{) -R 6 '' - * 3} , -Si (R 4) (R 5) -R 6 '' - * 3, -P (O) (R 4) -O-R 6 '' - * 3, - S (O) ₂ -R6 ^" -* ³ , -SR6 ^" -* ³ and -R6 ^" -* ³ are preferred, and a dialkylstannandiyl-cyano-alkanediyl group, dihydroxysilanediyl Diarylalkanediyloxycarbonyl group, hydroxyoxyphosphanediyloxyalkanediyloxycarbonyl group, thio-alkanediyloxycarbonyl group, thio-cycloalkanediyloxycarbonyl group and arenediylalkanediyl group are more preferable. Rustannandiyl-cyano-ethanediyl group, dihydroxysilanediyldiphenylmethanediyloxycarbonyl group, hydroxyoxyphosphanediyloxy-2,2-hexanediyloxycarbonyl group, thio-2,2-propanediyloxycarbonyl group, thio- A 2,2- (7,7-dimethyl) norbornanediyloxycarbonyl group and a naphthalenediylpropanediyl group are more preferred. * ³ indicates a site that binds to the carbon atom bonded to the A ^1. In this case, R ^{6 ″} is a divalent organic group having 1 to 20 carbon atoms and having a carbon atom at the terminal on the Z ¹ side in the above formula (2) (hereinafter, also referred to as “R ^{6 ′} ”). . Further, ^'the * ^2' the R ^{6 'is} a site that binds to the carbon atom bonded to the A ¹ (hereinafter, also referred to as "* ^4").

When A ¹ in the above formula (2) is an oxygen atom, -L is preferably -R ^{6 '} -* ³ from the viewpoint of further improving the LWR performance, the rectangular shape of the cross-sectional shape, and the film shrinkage suppressing property, The arenediylalkanediyl group is more preferred, and the benzenediylmethanediyl group is even more preferred.

When A ¹ in the above formula (2) is = N (R ¹ ), the above-mentioned L is -OR ^{6 ′} from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property. -* ³ , and R ¹ and R ^{6 ′} are preferably combined with each other to form a ring structure having 3 to 10 ring members together with the nitrogen atom bonded to R ¹ and the carbon atom bonded to this nitrogen atom. . In this case, it is preferable that R ¹ and R ^{6 ′} are combined with each other to form a ring structure having 3 to 10 ring members together with the nitrogen atom bonded to R ¹ and the oxygen atom bonded to R ^{6 ′} .

R ^{6 'is} combined with each other in R ¹ and L in the A ¹ in the formula (2), the ring members 3-10 which is formed together with the nitrogen atom and the carbon atom bonded to the nitrogen atom bound to R ¹ above As the ring structure, for example, R ¹ in A in Formula (1) and R ^{6 in} L are combined with each other, and the number of ring members formed together with the nitrogen atom bonded to R ¹ and the carbon atom bonded to this nitrogen atom The same ring structures as the structures exemplified as the ring structures 3 to 10 are exemplified. Among these, an azacycloalkane structure is preferable, and an azacycloheptane structure is more preferable, from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property.

The monovalent organic group having 1 to 20 carbon atoms represented by R ² and R ³ in Z ¹ in the above formula (2) includes an organic group of R ² and R ³ in Z in the above formula (1). And the same groups as those exemplified above. Among them, a hydrogen atom is preferable from the viewpoint of easiness of radical polymerization.

  Examples of the structural unit (II) include structural units represented by the following formulas (2-1) to (2-14) (hereinafter, also referred to as “structural units (II-1) to (II-14)”) and the like. Is mentioned.

  Among these, the structural units (II-1) to (II-8) are preferable from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property.

  [A] The lower limit of the content of structural unit (II) with respect to the total structural units constituting the polymer is preferably 0.1 mol%, more preferably 0.5 mol%, and still more preferably 1.0 mol%. . The upper limit of the content of the compound (II) is preferably 40 mol%, more preferably 30 mol%, and still more preferably 25 mol%. When the content ratio of the structural unit (II) is in the above range, the LWR performance, the rectangularity of the cross-sectional shape, and the property of suppressing film shrinkage are further improved.

<Structural unit (III)>
The structural unit (III) is a structural unit containing at least one of a lactone structure, a cyclic carbonate structure, and a sultone structure (excluding those contained in the structural unit (I)). [A] The polymer further has a structural unit (III) in addition to the structural unit (I) and the structural unit (II), whereby the solubility in a developer can be further adjusted. The performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property can be further improved. Further, the adhesion between the resist pattern formed from the radiation-sensitive resin composition (I) and the substrate can be improved. Here, the “lactone structure” refers to a structure having one ring (lactone ring) containing a group represented by —OC (O) —. Further, the “cyclic carbonate structure” refers to a structure having one ring (cyclic carbonate ring) including a group represented by —OC (O) —O—. The “sultone structure” refers to a structure having one ring (sultone ring) including a group represented by —OS (O) ₂ —.

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

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

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

  As the structural unit (III), among these, a structural unit having a norbornane lactone structure, a structural unit having an oxanorbornane lactone structure, and a structural unit having a γ-butyrolactone structure are preferable. Structural units derived from oxanorbornane lactone-yl (meth) acrylate, structural units derived from γ-butyrolactone-yl (meth) acrylate, and γ-butyrolactone-3-ylcyclohexane-1-yl (meth) Structural units derived from acrylate are more preferred.

  [A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) to all the structural units constituting the polymer [A] is preferably 1 mol%, and more preferably 10 mol%. Is more preferable, 20 mol% is further preferable, and 25 mol% is particularly preferable. On the other hand, the upper limit of the content ratio is preferably 85 mol%, more preferably 80 mol%, further preferably 75 mol%, and particularly preferably 70 mol%. When the content is in the above range, the adhesion of the resist pattern formed from the radiation-sensitive resin composition (I) to the substrate can be further improved. If the content is less than the lower limit, the adhesion of the resist pattern formed from the radiation-sensitive resin composition (I) to the substrate may be reduced. If the content exceeds the upper limit, the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage-suppressing property may decrease.

<Structural unit (IV)>
The structural unit (IV) is a structural unit containing a phenolic hydroxyl group. When KrF excimer laser light, EUV, electron beam or the like is used as the irradiation radiation, the polymer [A] further has a structural unit (IV) in addition to the structural units (I) and (II). As a result, the sensitivity of the radiation-sensitive resin composition (I) is improved. As a result, the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property can be further improved.

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

In the above formula (af), R ^AF1 is a hydrogen atom or a methyl group. L ^AF 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, a plurality of R ^AF2s may be the same or different. _nf2 is an integer of 1 to 3. However, n _f1 + n _f2 is 5 or less. n _af is an integer of 0 to 2.

As the above-mentioned R ^AF1 , a hydrogen atom is preferable from the viewpoint of copolymerizability of a monomer giving the structural unit (IV).

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 a group obtained by adding one hydrogen atom to those exemplified as the divalent organic group of L in the above formula (1). Among them, a group having 1 to 20 carbon atoms is exemplified.

  Of these, a monovalent chain hydrocarbon group is preferred, an alkyl group is more preferred, and a methyl group is even more preferred.

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

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

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

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

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

  Among these, the structural units (IV-1) and (IV-2) are preferred, and (IV-1) is more preferred.

  When the polymer [A] has the structural unit (IV), the lower limit of the content ratio of the structural unit (IV) to all the structural units constituting the polymer [A] is preferably 1 mol%, and more preferably 10 mol%. Is more preferable, and 20 mol% is further preferable. On the other hand, the upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, and still more preferably 75 mol%. By setting the content of the structural unit (IV) in the above range, the radiation-sensitive resin composition (I) can further improve the LWR performance, the rectangular shape of the cross-sectional shape, and the film shrinkage-suppressing property.

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

<Other structural units>
[A] The polymer may have other structural units other than the structural units (I) to (IV). 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 preferred, and a structural unit having a hydroxy group is more preferred.

  Other structural units include, for example, structural units represented by the following formulas.

In the above formula, ^RAH 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 relative to all the structural units constituting the polymer [A] is preferably 1 mol%, more preferably 20 mol%. Preferably, it is more preferably 40 mol%. On the other hand, the upper limit of the content ratio is preferably 80 mol%, more preferably 75 mol%, and still more preferably 70 mol%. The solubility of the polymer [A] in the developer can be more appropriately adjusted by adjusting the content of the other structural units within the above range. When the content ratio of other structural units exceeds the above upper limit, pattern formability may be reduced.

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

<[A] Method for synthesizing polymer>
[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 compound (X).

  Compound (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), and 2,2′-azobis (2-cyclopropyl) Azo radical initiators such as propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate;
Peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide and the like can be mentioned.

  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 and cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene;
Saturated carboxylic 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 and 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes and diethoxyethanes;
Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol and propylene glycol monomethyl ether;
Examples of the amide solvent include linear amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, and the like. And amides such as cyclic amides such as N-methylpyrrolidone and N, N'-dimethylimidazolidinone.

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

  The lower limit of the compounding ratio of the compound (X) with respect to all the monomers giving each structural unit including the compound (X) is preferably 0.1 mol%, more preferably 0.5 mol%, and more preferably 1.0 mol%. More preferred. The upper limit of the compounding ratio of the compound (X) is preferably 40 mol%, more preferably 30 mol%, and still more preferably 25 mol%. When the compounding ratio of the compound (X) is within the above range, the content ratio of the structural unit derived from the compound (X) introduced into the polymer [A] with respect to all the structural units becomes appropriate, and the LWR performance and the cross-sectional shape are improved. The rectangularity and the film shrinkage suppressing property are further improved.

  The lower limit of the compounding ratio of the compound (X) to the radical polymerization initiator is preferably 10 mol%, more preferably 30 mol%, and still more preferably 40 mol%. The upper limit of the compounding ratio of the compound (X) is preferably 1,000 mol%, more preferably 800 mol%, and still more preferably 700 mol%. By setting the compounding ratio of the compound (X) in the above range, the content ratio of the structural unit (II) introduced into the polymer [A] becomes appropriate, and the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property are obtained. Is more improved.

  The lower limit of the reaction temperature in the above polymerization is usually 40 ° C, preferably 50 ° C. The upper limit of the reaction temperature is usually 150 ° C, preferably 120 ° C. The lower limit of the reaction time is usually one hour. The upper limit of the reaction time is usually 48 hours, and preferably 24 hours.

  [A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 2,500, and 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] When the Mw of the polymer is in the above range, the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property are further improved. [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 preferably 1.1. The upper limit of the Mw / Mn is usually 5, preferably 3 and more preferably 2.5.

  [A] The structure derived from each structural unit of the polymer can be confirmed by NMR.

The Mw and Mn of the polymer in the present specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: For example, two “G2000HXL”, one “G3000HXL” and 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 substance: Monodisperse polystyrene

<[B] acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. The generated acid dissociates the acid dissociable group of the polymer [A] to form a carboxy group, a hydroxy group, etc., and changes the solubility of the polymer [A] in the developing solution. The radiation-sensitive resin composition (I), which can form a resist pattern from the resin composition (I), contains the acid generator [B] in the form of a low-molecular compound as described below (hereinafter, referred to as a low-molecular compound form). It may be appropriately referred to as “[B] acid generator”), an acid generating group incorporated as a part of the polymer, or both.

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

  Examples of the onium salt compound include a sulfonium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, a pyridinium salt and the like.

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

  [B] As the acid generator, an acid generator represented by the following formula (b) is preferable. [B] Since the acid generator has the following structure, [A] the diffusion length of the acid generated by exposure in the resist film due to the interaction with the structural unit (I) or the structural unit (II) of the polymer or the like. Is considered to be more appropriately shortened, and as a result, the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property of the radiation-sensitive resin composition (I) can be further improved.

In the above formula (b), R ^p1 is a monovalent group containing a ring structure having 6 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ^p5 and R ^p6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer of 0 to 10. ^np2 is an integer of 0 to 10. ^np3 is an integer of 1 to 10. If n ^p1 is 2 or more, the plurality of ^{R p2} may be the same or different. When n ^p2 is 2 or more, a plurality of R ^p3s may be the same or different, and a plurality of R ^p4s may be the same or different. When n ^p3 is 2 or more, a plurality of R ^p5 may be the same or different, and a plurality of R ^p6 may be the same or different. X ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent group containing a ring structure having 6 or more ring members represented by R ^p1 include a monovalent group containing an alicyclic structure having 6 or more ring members and an aliphatic heterocyclic structure having 6 or more ring members. Examples thereof include a monovalent group, a monovalent group containing an aromatic ring structure having 6 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 6 or more ring members.

Examples of the alicyclic structure having 6 or more ring members include monocyclic cycloalkane structures such as a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure;
A monocyclic cycloalkene structure such as a cyclohexene structure, a cycloheptene structure, a cyclooctene structure, or a cyclodecene structure;
Polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure and tetracyclododecane structure;
Examples include polycyclic cycloalkene structures such as a norbornene structure and a tricyclodecene structure.

Examples of the aliphatic heterocyclic structure having 6 or more ring members include a lactone structure such as a hexanolactone structure and a norbornane lactone structure;
Sultone structures such as a hexanosultone structure and a norbornane sultone structure;
An oxygen atom-containing heterocyclic structure such as an oxacycloheptane structure or an oxanorbornane structure;
A heterocyclic structure containing a nitrogen atom such as an azacyclohexane structure or a diazabicyclooctane structure;
Examples thereof include a sulfur atom-containing heterocyclic structure having a thiacyclohexane structure and a thianorbornane structure.

  Examples of the aromatic ring structure having 6 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, and an anthracene structure.

  Examples of the aromatic heterocyclic structure having 6 or more ring members include a heterocyclic structure containing an oxygen atom such as a furan structure, a pyran structure, and a benzopyran structure, and a heterocyclic structure containing a nitrogen atom such as a pyridine structure, a pyrimidine structure, and an indole structure. No.

The lower limit of the number of ring members of the ring structure of R ^p1 is preferably 7, more preferably 8, more preferably 9, and particularly preferably 10. On the other hand, the upper limit of the number of ring members is preferably 15, more preferably 14, more preferably 13, and particularly preferably 12. When the number of ring members is in the above range, the diffusion length of the acid can be further reduced appropriately, and as a result, the LWR performance, the rectangular shape of the cross-sectional shape, and the film of the radiation-sensitive resin composition (I) can be obtained. Shrinkage suppression can be further improved.

Some or all of the hydrogen atoms of the ring structure of R ^p1 may be substituted with a substituent. Examples of the substituent include a fluorine atom, a chlorine atom, a bromine atom, a halogen atom such as an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, And an acyloxy group. Of these, a hydroxy group is preferred.

As R ^p1 , among these, a monovalent group containing an alicyclic structure having 6 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members are preferable, and an aliphatic group having 9 or more ring members is preferable. A monovalent group containing a ring structure and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members are more preferable, and an adamantyl group, a hydroxyadamantyl group, a norbornane lactone-yl group, a norbornane sultone-yl group, and a 5- An oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecane-yl group is more preferred, and an adamantyl group is particularly preferred.

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, and the like. The divalent linking group represented by R ^p2 is preferably a carbonyloxy group, a sulfonyl group, an alkanediyl group and a cycloalkanediyl group, more preferably a carbonyloxy group and a cycloalkanediyl group, and more preferably a carbonyloxy group and norbornanediyl. Groups are more preferred, and carbonyloxy groups are particularly preferred.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include an alkyl group having 1 to 20 carbon atoms. Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include a fluorinated alkyl group having 1 to 20 carbon atoms. As R ^p3 and R ^p4 , a hydrogen atom, a fluorine atom and a fluorinated alkyl group are preferred, a fluorine atom and a perfluoroalkyl group are more preferred, and a fluorine atom and a trifluoromethyl group are even more preferred.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p5 and R ^p6 include a fluorinated alkyl group having 1 to 20 carbon atoms. As R ^p5 and R ^p6 , a fluorine atom and a fluorinated alkyl group are preferred, a fluorine atom and a perfluoroalkyl group are more preferred, a fluorine atom and a trifluoromethyl group are still more preferred, and a fluorine atom is particularly preferred.

As n ^p1 , an integer of 0 to 5 is preferable, an integer of 0 to 3 is more preferable, an integer of 0 to 2 is more preferable, and 0 and 1 are particularly preferable.

The n ^p2, preferably an integer of 0 to 5, more preferably an integer of 0 to 2, more preferably 0 and 1, 0 being particularly preferred.

As ^np3 , an integer of 1 to 5 is preferable, an integer of 1 to 4 is more preferable, an integer of 1 to 3 is more preferable, and 1 and 2 are particularly preferable.

The monovalent radiation-sensitive onium cation represented by X ⁺ is a cation that decomposes upon irradiation with exposure light. In the exposed portion, a sulfonic acid is generated from a proton generated by the decomposition of the photodegradable onium cation and a sulfonate anion. Examples of the monovalent radiation-sensitive onium cation represented by X ⁺ include a cation represented by the following formula (ba) (hereinafter, also referred to as “cation (ba)”) and a cation represented by the following formula (b -B) (hereinafter also referred to as “cation (bb)”), cation represented by the following formula (bc) (hereinafter also referred to as “cation (bc)”), and the like. Is mentioned.

In the above formula (ba), R ^B3 , R ^B4 and R ^B5 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkyl group. aromatic hydrocarbon group having 6 to 12 carbon _atoms, a or a -OSO ^{2 -R BB1} or _-SO 2 ^{-R BB2,} or two or more are combined with each other configured ring of these groups . R ^BB1 and R ^BB2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, 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 formula (bb), ^RB6 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 to 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 to 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. _nb2 is an integer of 0 to 3. ^RB8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. _nb1 is an integer of 0 to 2.

In the above formula ( ^bc ), R ^B9 and R ^B10 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon group having 6 or more carbon atoms. 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 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, 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 B9,} R B10, R ^BB3 and when ^{R BB4} is plural respective plurality of ^{R B9, R B10, R BB3} and ^{R BB4} may have respectively the same or different.

R ^B3, as the ^{R B4,} R ^B5, an unsubstituted linear alkyl group represented by ^{R B6, R} B7, ^{R B9} and ^{R B10,} a methyl group, an ethyl group, n- propyl group, n- Butyl group and the like.

R ^B3, as is ^{R B4, R B5,} an unsubstituted branched alkyl group represented by ^{R B6, R} B7, ^{R B9} and ^{R B10,} for example, i- propyl, i- butyl group, sec- butyl group , A t-butyl group and the like.

The ^{R B3, R B4, R B5} , unsubstituted aromatic hydrocarbon groups represented by ^{R B9} and ^{R B10,} a phenyl group, a tolyl group, a xylyl group, mesityl group, an aryl group such as phenyl or naphthyl;
And aralkyl groups such as benzyl group and phenethyl group.

Examples of the unsubstituted aromatic hydrocarbon group represented by ^RB6 and ^RB7 include a phenyl group, a tolyl group, and a benzyl group.

The divalent organic group represented by R ^B8, for example, divalent out of the illustrated ones as the organic group group having 1 to 20 carbon atoms, such as the L in the formula (1).

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

As ^RB3 , ^RB4 , ^RB5 , ^RB6 , ^RB7 , ^RB9 and ^RB10 , an unsubstituted linear or branched alkyl group, fluorinated alkyl group, unsubstituted monovalent aromatic carbon hydrogen _group, a -OSO ^{2 -R BB5} and _-SO 2 ^{-R BB5,} more preferably a monovalent aromatic hydrocarbon group having a fluorinated alkyl group and unsubstituted, more preferably a fluorinated alkyl group. R ^BB5 is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As b1, b2 and b3 in the formula (ba), integers of 0 to 2 are preferable, 0 and 1 are more preferable, and 0 is further preferable. B4 in the formula (bb) is preferably an integer of 0 to 2, more preferably 0 and 1, and still more preferably 1. b5 is preferably an integer of 0 to 2, more preferably 0 and 1, and even more preferably 0. The n _b2, preferably 2 and 3, 2 is more preferable. As n _b1 , 0 and 1 are preferable, and 0 is more preferable. In formula (bc), b6 and b7 are preferably integers of 0 to 2, more preferably 0 and 1, and still more preferably 0.

X ⁺ is preferably a cation (ba) or a cation (bb) among these, and a triphenylsulfonium cation and 1- [2- (4-cyclohexylphenylcarbonyl) propan-2-yl] tetrahydro The thiophenium cation is more preferred.

  Examples of the acid generator represented by the formula (b) include compounds represented by the following formulas (b-1) to (b-15) (hereinafter, referred to as “compounds (b-1) to (b-15)”). And the like).

In the above formulas (b-1) to (b-15), X ⁺ is a monovalent radiation-sensitive onium cation.

  [B] The acid generator is preferably an onium salt compound, and more preferably the compounds (b-2) and (b-11).

  When the acid generator [B] is the acid generator [B], the lower limit of the content of the acid generator [B] is preferably 0.1 part by mass with respect to 100 parts by mass of the polymer [A]. 0.5 parts by mass is more preferable, and 1 part by mass is further preferable. As a maximum of the above-mentioned content, 30 mass parts is preferred, 20 mass parts is more preferred, and 15 mass parts is still more preferred. [B] By setting the content of the acid generator in the above range, the sensitivity and developability of the radiation-sensitive resin composition (I) are improved, and as a result, LWR performance, rectangularity in cross-sectional shape, and suppression of film shrinkage are achieved. Performance can be improved. [B] One or more acid generators can be used.

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

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

In the above formula (c-1), R ^C1 , R ^C2 and R ^C3 are each independently a hydrogen atom, a linear, branched or cyclic alkyl group, aryl group or aralkyl group which may be substituted. 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;
Polymers such as dimethylaminoethyl acrylamide are exemplified.

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone. Can be

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

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

  Further, as the acid diffusion controller, a compound having an acid dissociable group can be used. 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, and N- (t-butoxycarbonyl) benzimidazole. (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 photo-degradable base that is exposed to light to generate a weak acid can be used. Examples of the photodisintegrable base include an onium salt compound which decomposes upon exposure to light and loses the acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (c-2) and an iodonium salt compound represented by the following formula (c-3).

In the formulas (c-2) and (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 a formula represented by the following formula (c-5) Anion. Here, R ^CC1 is an alkyl group, an aryl group or an aralkyl group.

In the above formula (c-4), R ^C9 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 a fluorine atom, or a carbon atom having 1 to 12 carbon atoms. 12 straight-chain or branched alkoxyl groups. _nc1 is an integer of 0 to 2. When _nc1 is 2, a plurality of ^RC9s may be the same or different.

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

  When the radiation-sensitive resin composition (I) contains the acid diffusion controller [C], the lower limit of the content of the acid diffusion controller [C] relative to 100 parts by mass of the polymer [A] is 0.1. A mass part is preferred, and 0.3 mass part is more preferred. On the other hand, the upper limit of the content is preferably 20 parts by mass, more preferably 15 parts by mass, and still more preferably 10 parts by mass.

<[D] polymer>
The polymer [D] is a polymer having a higher fluorine atom content than the polymer [A]. Since the radiation-sensitive composition (I) contains the polymer [D], when the resist film is formed, the distribution of the polymer is changed by the oil-repellent characteristic of the polymer [D] in the film. It tends to be unevenly distributed in the vicinity. Therefore, at the time of immersion exposure, elution of the acid generator, the acid diffusion controller, and the like into the immersion medium can be suppressed. Further, due to the water-repellent characteristics of the polymer [D], the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and generation of bubble defects can be suppressed. Further, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure can be performed without leaving water droplets. When the radiation-sensitive resin composition (I) contains the polymer [D], a resist film suitable for the liquid immersion exposure method can be formed.

When the radiation-sensitive resin composition (I) contains a polymer [D], the lower limit of the fluorine atom content of the polymer [D] is preferably 1% by mass, more preferably 2% by mass, and 4% by mass. % By mass is more preferable, and 7% by mass is particularly preferable. On the other hand, the upper limit of the content is preferably 60% by mass, more preferably 40% by mass, and still more preferably 30% by mass. [D] If the fluorine atom content of the polymer is less than the above lower limit, the hydrophobicity of the resist film surface may decrease. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by measuring the ¹³ C-NMR spectrum.

  [D] The form in which the fluorine atom is contained in the polymer is not particularly limited. The fluorine atom may be bonded to the main chain or may be bonded to the side chain. ) "). [D] The polymer preferably has a structural unit containing an acid-dissociable group, in addition to the structural unit (V), from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the property of suppressing film shrinkage. Examples of the structural unit containing an acid dissociable group include the structural unit (I) in the polymer [A].

  [D] The polymer preferably has an alkali-dissociable group. [D] When the polymer has an alkali-dissociable group, the surface of the resist film can be effectively changed from hydrophobic to hydrophilic at the time of alkali development, and the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property are more improved. improves. The “alkali dissociable group” is a group that replaces a hydrogen atom of a carboxy group, a hydroxy group, or the like, and dissociates in an alkaline aqueous solution (eg, a 2.38 mass% aqueous solution of tetramethylammonium hydroxide at 23 ° C.). Group.

  As the structural unit (V), 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, “structure”) Unit (Vb) ”) is preferred. The structural unit (V) may have one or two or more structural units (Va) and structural units (Vb), respectively.

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

In the above formula (ff1), R ^F1 is a hydrogen atom, a methyl group or a trifluoromethyl group. L ^F1 represents a single bond, an oxygen atom, a sulfur _{atom, -CO-O -, - SO} 2 -O-NH -, - is 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.

R ^F1 is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of copolymerizability of a monomer giving the structural unit (Va).

As the _{^{L F1, -CO-O -,}} - SO 2 -O-NH -, - CO-NH- and -O-CO-NH- are preferred, -CO-O-it is more preferred.

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, 2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n-butyl group , A perfluoro i-butyl group, a perfluoro t-butyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 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 the above, R ^F2 is preferably a fluorinated chain hydrocarbon group, such as a 2,2,2-trifluoroethyl group and a 1,1,1,3,3,3-hexafluoro-2-propyl group. Groups are more preferred.

  When the polymer [D] has the structural unit (Va), the lower limit of the content ratio of the structural unit (Va) to all the structural units constituting the polymer [D] is preferably 3 mol%, and more preferably 5 mol%. Is more preferred. On the other hand, the upper limit of the content ratio is preferably 90 mol%, more preferably 70 mol%, and still more preferably 50 mol%. With such a content ratio, the fluorine atom content of the polymer [D] can be more appropriately adjusted.

<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, (u + 1) -valent hydrocarbon group or an oxygen atom at the terminal of ^{R F5} side of the hydrocarbon group having 1 to 20 carbon atoms, a sulfur ^{atom, -NR FF1} -, carbonyl group, -CO- 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. ^LF2 is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. L ^F3 represents 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 ^RF6 . ^RF6 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.

From the viewpoint of copolymerizability of the monomer giving the structural unit (Vb), R ³ is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

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 formula (a-1). And the like excluding.

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

As the above 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, and a single bond and an alkanediyl group having 1 to 4 carbon atoms are further preferable. A single bond, a methanediyl group and a propanediyl group are particularly preferred.

As the divalent organic group having 1 to 20 carbon atoms represented by R ^F5 , for example, one of the monovalent organic groups having 1 to 20 carbon atoms exemplified as R ^A2 in the formula (a-1) may be used. And the like, excluding the hydrogen atom.

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

The divalent chain fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by L ^F2, such as fluoro methane diyl group, difluoromethane diyl group, fluoro-ethanediyl group, difluoroethane diyl group, tetrafluoroethane diyl Fluorinated alkanediyl groups such as a group, hexafluoropropanediyl group, octafluorobutanediyl group;
And fluorinated alkenediyl groups such as a fluoroethenediyl group and a difluoroethenediyl group. Among these, a fluorinated alkanediyl group is preferred, and a difluoromethanediyl group is more preferred.

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 have the same meaning as in the above formula (ff2). When u is 2 or 3, a plurality of L ^F2 and R ^F6 may be the same or different.

  When the polymer [D] has the structural unit (Vb), the lower limit of the content ratio of the structural unit (Vb) to all the structural units constituting the polymer [D] is preferably 10 mol%, and more preferably 20 mol%. Is more preferable, and 40 mol% is still more preferable. On the other hand, the upper limit of the content ratio is preferably 90 mol%, more preferably 85 mol%, and still more preferably 80 mol%. With such a content ratio, the water repellency, hydrophilicity, and the like of the surface of the resist film formed from the radiation-sensitive resin composition (I) before and after alkali development can be more appropriately adjusted.

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

  [D] As a minimum of content rate of a structural unit containing an acid dissociable group 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, the upper limit of the content ratio is preferably 85 mol%, more preferably 80 mol%, and still more preferably 75 mol%. [D] By setting the content of the structural unit containing an acid-dissociable group in the polymer within the above range, the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage-suppressing property can be further improved.

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

  The polymer [D] can be synthesized in the same manner as the polymer [A] described above.

  [D] The weight average molecular weight (Mw) of the polymer in terms of polystyrene measured by gel permeation chromatography (GPC) is not particularly limited, but the lower limit 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 setting the Mw of the polymer to the above range, the coating properties, LWR performance, rectangularity of the cross-sectional shape, and film shrinkage suppressing properties of the radiation-sensitive resin composition (I) are further improved. [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 decrease.

  [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 still more preferably 2.

<[E] solvent>
The radiation-sensitive resin composition (I) may contain a solvent [E], if necessary. [E] Solvent dissolves or disperses [A] polymer and [B] acid generator, and [C] acid diffusion controller, [D] polymer and other optional components contained as necessary. There is no particular limitation as long as it is possible. [E] The solvent includes, for example, alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents and the like.

Examples of the alcohol-based solvent include aliphatic monoalcohol-based 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 polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms such as propylene glycol monoethyl ether.

Examples of the ether solvent include dialiphatic ether solvents such as diethyl ether, dipropyl ether and dibutyl ether;
Aromatic ring ether solvents such as anisole and diphenyl ether;
And 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 and methylcyclohexanone;
Diketone solvents such as 2,4-pentanedione and acetonylacetone are exemplified.

Examples of the amide solvent include linear amides such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, and the like. System solvent;
And cyclic amide solvents such as N-methylpyrrolidone and N, N'-dimethylimidazolidinone.

Examples of the ester solvent 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;
Polyvalent carboxylic 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 And aliphatic hydrocarbon solvents such as methylcyclohexane;
Aroma such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n-amylnaphthalene Group hydrocarbon solvents and the like.

  Of these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether carboxylate solvents and cyclic ketone solvents are more preferred, and propylene glycol monomethyl ether acetate and cyclohexanone are even more preferred. [E] The solvent can be used alone or in combination of two or more.

<[F] uneven distribution accelerator>
The radiation-sensitive resin composition (I) may optionally contain [F] a localization promoting agent. [F] The localization accelerator has an effect of more efficiently segregating the polymer [D] on the resist film surface when the radiation-sensitive resin composition (I) contains the polymer [D]. Things. By adding the [F] uneven distribution accelerator to the radiation-sensitive resin composition (I), the amount of the water-repellent polymer additive to be added can be made smaller than before. Therefore, it is possible to further suppress the elution of the components from the resist film into the immersion liquid without impairing the LWR performance, the rectangularity of the cross-sectional shape, and the ability to suppress film shrinkage, and to perform the immersion exposure at a higher speed by high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface that suppresses defects due to immersion such as watermark defects. Examples of the [F] uneven distribution accelerator that can be used include low molecular weight compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point at 1 atm of 100 ° C. or more. Specific examples of such a compound include a lactone compound, a carbonate compound, a nitrile compound, and a polyhydric alcohol.

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

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

  Examples of the nitrile compound include succinonitrile.

  Examples of the polyhydric alcohol include glycerin.

  [F] As the uneven distribution accelerator, a lactone compound is preferable, and γ-butyrolactone is more preferable, from the viewpoint of further improving the LWR performance, the rectangularity of the cross-sectional shape, and the film shrinkage suppressing property.

  When the radiation-sensitive resin composition (I) contains the [F] uneven distribution accelerator, the lower limit of the content of the above [F] uneven distribution accelerator is as follows: [A] 100 parts by mass of the polymer. 10 parts by mass is preferable, 15 parts by mass is more preferable, 20 parts by mass is further preferable, and 25 parts by mass is particularly preferable. The upper limit of the content of the [F] uneven distribution accelerator is preferably 500 parts by mass, more preferably 400 parts by mass, still more preferably 300 parts by mass, and more preferably 200 parts by mass, based on 100 parts by mass of the polymer [A]. Parts are particularly preferred.

<Other optional ingredients>
The radiation-sensitive resin composition (I) may contain other optional components in addition to the components [A] to [F]. Examples of the other optional components include a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. One or more of these other optional components may be used in combination.

<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, and polyethylene glycol dilaurate. Nonionic surfactants such as stearate; commercially available products include “KP341” manufactured by Shin-Etsu Chemical Co., Ltd., “Polyflow No. 75 and No. 95” manufactured by Kyoeisha Chemical Co., Ltd., and “Ftop EF301” manufactured by Tochem Products Co., Ltd. EF303 and EF352, DIC's MegaFac F171 and F173, Sumitomo 3M's Florad FC430 and FC431, Asahi Glass Industries' 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 based on 100 parts by mass of the polymer [A].

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

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantane carboxylic acid, 2-adamantanone, and t-butyl 1-adamantane carboxylate;
Deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, 2-ethoxyethyl deoxycholate;
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 . 17, 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 based on 100 parts by mass of the polymer [A]. .

<Sensitizer>
The sensitizer has the effect of increasing the amount of acid generated from the acid generator [B], 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 based on 100 parts by mass of the polymer (A).

<Method of 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] ] It can be prepared by mixing a localization accelerator and other optional components at a predetermined ratio, and preferably filtering the mixture with a membrane filter having a pore size of about 0.2 μm. The lower limit of the solid concentration of the radiation-sensitive resin composition (I) is preferably 0.1% by mass, more preferably 0.5% by mass, still more preferably 1% by mass, and particularly preferably 1.5% by mass. . The upper limit of the solid content concentration of the radiation-sensitive resin composition (I) is preferably 50% by mass, more preferably 30% by mass, further preferably 20% by mass, and particularly preferably 10% by mass. Here, the “solid concentration” of the radiation-sensitive resin composition (I) refers to the mass of a component obtained by removing a solvent from the radiation-sensitive resin composition (I) based on the total mass of the radiation-sensitive resin composition (I). The fraction.

<Radiation-sensitive resin composition (II)>
The radiation-sensitive resin composition (II) contains a polymer [A-1] and a radiation-sensitive acid generator. The radiation-sensitive resin composition (II) may contain, as preferred components, an acid diffusion controller, a polymer having a higher fluorine atom content than the [A-1] polymer, a solvent, and a localization accelerator. Further, other optional components may be contained as long as the effects of the present invention are not impaired. Radiation-sensitive acid generator, acid-diffusion controller, polymer having a higher fluorine atom content than [A-1] polymer, solvent, uneven distribution accelerator and other optional components of radiation-sensitive resin composition (II) As the components, each [B] acid generator, [C] acid diffusion controller, [D] polymer, [E] solvent, [F] uneven distribution accelerator, and [B] acid generator of the radiation-sensitive resin composition (I). The same components as those described as other optional components can be used. The preferred components are the same as in the case of the radiation-sensitive resin composition (I). Hereinafter, the polymer [A-1] will be described.

<[A-1] polymer>
[A-1] The polymer is a polymer having a first structural unit and a second structural unit. The radiation-sensitive resin composition (II) can form a resist pattern excellent in LWR performance, rectangular cross-sectional shape, and film shrinkage suppression property when the polymer [A-1] has the second structural unit. it can. The reason why the radiation-sensitive resin composition (II) has the above-described structure to achieve the above-described effects is not necessarily clear, but can be inferred, for example, as follows. That is, the polymer [A-1] has the second structural unit in the main chain. Due to the steric factor of the second structural unit, the [A-1] polymer has an expanded spatial extent. In addition, since the polymer [A-1] has the second structural unit in the main chain, it has one or more structural units having the above characteristics. As a result, the diffusion length of the acid generated from the acid generator in the resist film becomes appropriately short, and the LWR performance and the rectangularity of the cross-sectional shape become excellent. Further, it is considered that the evaporation of the low-molecular compound at the time of PEB is suppressed, and the film shrinkage suppressing property is improved.

  [A-1] The polymer can be synthesized by radical polymerization in the presence of the compound (X). The second structural unit derived from the compound (X) can be introduced into the [A-1] polymer by radical polymerization in the presence of the compound (X).

  [A-1] The polymer includes, in addition to the first structural unit and the second structural unit, a structural unit including at least one of a lactone structure, a cyclic carbonate structure, and a sultone structure, and a structural unit including a phenolic hydroxyl group. And may have other structural units other than these structural units.

  [A-1] The first structural unit of the polymer is the same as that exemplified as the structural unit (I) of the polymer [A]. [A-1] The second structural unit of the polymer is the same as that exemplified as the structural unit (II) of the polymer [A]. [A-1] The structural unit containing at least one of the lactone structure, cyclic carbonate structure and sultone structure of the polymer is the same as that exemplified as the structural unit (III) of the polymer [A]. . [A-1] The structural unit containing a phenolic hydroxyl group of the polymer is the same as that exemplified as the structural unit (IV) of the polymer [A]. [A-1] The other structural units of the polymer are the same as those exemplified above as the other structural units of the polymer [A]. The preferred and content ratios of these structural units are the same as in the case of the polymer [A].

<[A-1] Method for synthesizing polymer>
[A-1] The polymer is obtained by radical polymerization using a monomer giving each structural unit, a radical polymerization initiator, and the like in a solvent in the presence of compound (X). [A-1] As the compound (X), radical polymerization initiator, solvent and the like used in the method for synthesizing the polymer, those similar to those used for the synthesis of [A] polymer can be used. The preferable ones and the mixing ratio of each of them are the same as those in the case of the synthesis of the polymer [A]. The reaction temperature and the reaction time in the polymerization are the same as those in the synthesis of the polymer [A].

  [A-1] The Mw and Mw / Mn of the polymer are the same as those of the [A] polymer.

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

<Method of preparing radiation-sensitive resin composition (II)>
The radiation-sensitive resin composition (II) can be prepared in the same manner as in the radiation-sensitive resin composition (I).

<Method of forming resist pattern>
The method for forming a resist pattern includes a step of forming a resist film (hereinafter, also referred to as a “resist film forming step”), a step of exposing the resist film (hereinafter, also referred to as an “exposure step”), and a step of exposing the exposed resist film. A step of developing (hereinafter, also referred to as a “development step”) is provided, and the resist film is formed from the radiation-sensitive resin composition (I) or the radiation-sensitive resin composition (II). The radiation-sensitive resin composition (I) and the radiation-sensitive resin composition (II) may be collectively referred to as the radiation-sensitive resin composition.

  According to the method for forming a resist pattern, since the radiation-sensitive resin composition is used, a resist pattern having excellent LWR performance, rectangular cross-sectional shape, and film shrinkage-suppressing property can be formed. Hereinafter, each step of the resist pattern forming method will be described.

<Resist film formation step>
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 substrates such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, an organic or inorganic antireflection film disclosed in, for example, Japanese Patent Publication No. 6-12452 or JP-A-59-93448 may be formed on a substrate. Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. After the application, a pre-bake (PB) may be performed as needed to volatilize the solvent in the coating film. The lower limit of the PB temperature is usually 60 ° C, preferably 80 ° C. The upper limit of the PB temperature is usually 140 ° C., preferably 120 ° C. The lower limit of the PB time is usually 5 seconds, preferably 10 seconds. The upper limit of the PB time is usually 600 seconds, and preferably 300 seconds. The lower limit of the average thickness of the formed resist film is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness of the resist film is preferably 1,000 nm, more preferably 500 nm.

<Exposure process>
In this step, the resist film formed in the resist film forming step is irradiated with radiation through a photomask or the like (in some cases, through an immersion medium such as water) to be exposed. Examples of the 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 a 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 further preferable. preferable.

  When the exposure is performed by immersion exposure, examples of the immersion liquid 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 temperature coefficient of the refractive index as small as possible so as to minimize distortion of the optical image projected on the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoint of easy availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. The additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coat on the lower surface of the lens. Distilled water is preferred as the water used.

  After the above exposure, post-exposure bake (PEB) is performed to dissociate the acid dissociable groups of the [A] polymer and the like by the acid generated from the [B] acid generator by the exposure in the exposed portions of the resist film. Is preferably promoted. Due to this PEB, a difference is caused between the exposed part and the unexposed part due to solubility in a developing solution. The lower limit of the PEB temperature is usually 50 ° C., preferably 80 ° C. 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, 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 above 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 dry. As a developing method in the developing step, a positive resist pattern may be formed by developing with an alkaline solution, or a negative resist pattern may be formed by developing with a liquid containing an organic solvent.

  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 thereof include an alkali solution in which at least one kind of an alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved. Among them, the TMAH solution is preferred.

  In the case of organic solvent development, examples of the developer include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, or solvents containing organic solvents. Examples of the organic solvent include one or more of the solvents listed as the solvent [E] in the radiation-sensitive resin composition. Of these, ester solvents are preferred, and n-butyl acetate is more preferred. The lower limit of the content of the organic solvent in the developer is preferably 80% by mass, more preferably 90% by mass, still more preferably 95% by mass, and particularly preferably 99% by mass. Components other than the organic solvent in the developer include, for example, water and silicone oil.

  As a developing method, for example, a method in which a substrate is immersed in a bath filled with a developing solution for a certain period of time (dip method), a method in which the developing solution is raised on the substrate surface by surface tension and is stopped for a certain period of time (paddle method) ), A method of spraying a developer onto the substrate surface (spray method), a method of continuously applying a developer while scanning a developer application nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method). And the like.

  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 by the following method.

[Mw, Mn and Mw / Mn]
Mw and Mn were measured using a Tosoh GPC column (two “G2000HXL”, one “G3000HXL”, one “G4000HXL”), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1. The 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., and detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
^{The 13} C-NMR analysis was measured using a nuclear magnetic resonance apparatus “AVANCE III HD” manufactured by 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
Resonant frequency: 175 MHz
Flip angle of detection pulse: 90 °
Data acquisition time: 0.7078 seconds Delay time: 1.2139 seconds Number of integrations: 1800 times (measurement time 1 hour 15 minutes)
Measurement temperature: 25 ° C

<Synthesis of Compound (X)>
[Synthesis Example 1] (Synthesis of Compound (X-1))
Round-bottom flask 1000mL methyl 2- (bromomethyl) acrylate 50mmol as ^{_{precursors, (C 4 H 9) 4}} N + Br - the 100mmol and _C 6 _H 5 Cl300mL added, and stirring was initiated at 80 ° C.. An aqueous solution containing a 100 mmol aqueous solution of sodium hydrogen sulfide was slowly added dropwise thereto. After completion of the dropwise addition, the mixture was stirred at 80 ° C. for 5 hours, and extracted with hexane. Thereafter, the organic layer was dried with an anhydrous sodium sulfate aqueous solution, the solvent was distilled off, and the residue was purified by column chromatography to obtain (X-1 ′) (yield 77%). Next, (X-1 ′) 20 mmol, a 5 mass% aqueous sodium hydroxide solution 100 mL, and tetrahydrofuran 150 mL were added to a 500 mL round bottom flask, and stirring was started at 60 ° C. After 10 hours, the reaction solution was ice-bathed, 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 (X-1 ″) (yield 92%). Next, 10 mmol of (X-1 ″), 15 mmol of CH ₃ C (＝ O) CH ₃ , 15 mmol of 10-camphorsulfonic acid, and 50 mL of CHCl ₃ were added to a 300 mL round bottom flask, and stirring was started at 100 ° C. After 72 hours, the reaction was cooled in an ice bath and extracted with CHCl ₃ . The organic layer was dried over anhydrous sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography to obtain compound (X-1) (yield 73%).

[Synthesis Examples 2 to 8] (Synthesis of Compounds (X-2) to (X-8))
Compounds represented by the following formulas (X-2) to (X-8) were synthesized by appropriately selecting the types and amounts of the precursor and the solvent and performing the same operations as in Synthesis Example 1.

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

[[A] Synthesis of polymer]
[Synthesis Example 9] (Synthesis of polymer (A-1))
63.93 g (38 mol%) of compound (M-1), 71.46 g (42 mol%) of compound (M-6) and 50.46 g (20 mol%) of compound (M-7) were added to 250 g of 2-butanone. And 2,2′-azobisisobutyronitrile (5 mol% based on all monomers) as an initiator was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-1) (yield: 77%). Mw of this polymer (A-1) was 6,800 and Mw / Mn was 1.45. In addition, as a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from (M-1), (M-6) and (M-7) were 31.7 mol% and 48.6 mol%, respectively. And 19.7 mol%.

[Synthesis Example 10] (Synthesis of polymer (A-2))
60.90 g (38.0 mol%) of compound (M-1), 68.06 g (42.0 mol%) of compound (M-6) and 47.94 g (20.0 mol%) of compound (M-7) Was dissolved in 250 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on all monomers) and 7.02 g of octanethiol (all monomers) were used as initiators. (5.0 mol%) was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-2) (yield: 75%). Mw of this polymer (A-2) was 6,890, and Mw / Mn was 1.47. In addition, as a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from (M-1), (M-6) and (M-7) were 32.3 mol%, 48.2 mol% and It was 19.5 mol%. ^{By 13} C-NMR, it was confirmed that a structure derived from octanethiol was introduced into the terminal of the polymer (A-2).

[Synthesis Example 11] (Synthesis of polymer (A-3))
60.90 g (36.2 mol%) of compound (M-1), 68.06 g (40.0 mol%) of compound (M-6) and 47.94 g (19.0 mol%) of compound (M-7) Was dissolved in 250 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on all monomers including compound (X-1)) as an initiator and compound ( X-1) 7.59 g (4.8 mol%) was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-3) (yield: 77%). Mw of this polymer (A-3) was 6,800, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratio of the structural units derived from (M-1), (M-6), (M-7) and (X-1) was 37.5 mol%, respectively. 38.4 mol%, 20.3 mol% and 3.8 mol%.

[Synthesis Example 12] (Synthesis of polymer (A-4))
49.12 g (29.2 mol%) of compound (M-1), 54.96 g (32.3 mol%) of compound (M-6) and 38.86 g (15.4 mol%) of compound (M-7) Was dissolved in 250 g of 2-butanone, and further, 2,2′-azobisisobutyronitrile (8 mol% based on all monomers including compound (X-2)) as an initiator and compound ( X-2) 55.06 g (23.1 mol%) was charged to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the prepared monomer solution was added dropwise over 4 hours using a dropping funnel, and after completion of the addition, the mixture was further stirred at 80 ° C. for 2 hours. After the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-4) (yield: 64%). Mw of this polymer (A-4) was 7,000, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the content ratio of the structural units derived from (M-1), (M-6), (M-7) and (X-2) was 30.2 mol%, respectively. 28.3 mol%, 19.5 mol% and 22.0 mol%.

[Synthesis Example 13] (Synthesis of polymer (A-5))
58.21 g (34.6 mol%) of compound (M-1), 65.00 g (38.2 mol%) of compound (M-6) and 45.92 g (18.2 mol%) of compound (M-7) Is dissolved in 250 g of 2-butanone, and 2,2′-azobisisobutyronitrile (2 mol% based on all monomers including compound (X-3)) as an initiator and compound ( X-3) was added, and a monomer solution was prepared by charging 21.77 g (9.0 mol%). On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-5) (yield: 75%). Mw of this polymer (A-5) was 7,000, and Mw / Mn was 1.48. As a result of ¹³ C-NMR analysis, the content ratio of the structural units derived from (M-1), (M-6), (M-7) and (X-3) was 36.0 mol%, 35.6 mol%, and 20.4 mol% and 8.0 mol%.

[Synthesis Example 14] (Synthesis of polymer (A-6))
58.21 g (34.6 mol%) of compound (M-1), 65.00 g (38.2 mol%) of compound (M-6) and 45.92 g (18.2 mol%) of compound (M-7) Is dissolved in 250 g of 2-butanone, and 2,2′-azobisisobutyronitrile (2 mol% based on all monomers including compound (X-4)) as an initiator and compound ( X-4) 28.11 g (9.0 mol%) was added to prepare a monomer solution. On the other hand, 150 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, after adding 200 g of 2-butanone to the polymerization reaction solution, the mixture was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-6) (yield 74%). Mw of this polymer (A-6) was 6,800, and Mw / Mn was 1.49. As a result of ¹³ C-NMR analysis, the proportions of the structural units derived from (M-1), (M-6), (M-7) and (X-4) were 36.4 mol% and 36 It was 0.5 mol%, 21.1 mol% and 6.0 mol%.

[Synthesis Example 15] (Synthesis of polymer (A-7))
78.52 g (40 mol%) of compound (M-2), 52.48 g (20 mol%) of compound (M-5), 44.45 g (20 mol%) of (M-8) and compound (M-10) 52.85 g (20 mol%) was dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (1 mol% based on all monomers) was further charged as an initiator. To prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, this polymerization reaction solution was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-7) (yield 81%). Mw of this polymer (A-7) was 6,850, and Mw / Mn was 1.44. As a result of ¹³ C-NMR analysis, the ratios of the structural units derived from (M-2), (M-5), (M-8) and (M-10) were 34.8 mol% and 19%, respectively. 0.4 mol%, 20.6 mol% and 25.2 mol%.

[Synthesis Example 16] (Synthesis of polymer (A-8))
58.54 g (34.8 mol%) of compound (M-2), 45.66 g (17.4 mol%) of compound (M-5), 38.67 g (17.4 mol%) of (M-8) and 45.98 g (17.4 mol%) of compound (M-10) was dissolved in 400 g of 2-butanone, and further, 2,2′-azobisisobutyronitrile (compound (X-5)) was used as an initiator. And the compound (X-5) 32.27 g (13.0 mol%) was added thereto to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, this polymerization reaction solution was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-8) (yield 70%). Mw of this polymer (A-8) was 6,750 and Mw / Mn was 1.44. As a result of ¹³ C-NMR analysis, the ratio of the structural units derived from (M-2), (M-5), (M-8), (M-10) and (X-5) was 35% each. 8.8 mol%, 15.7 mol%, 18.4 mol%, 22.1 mol% and 8.0 mol%.

[Synthesis Example 17] (Synthesis of polymer (A-9))
65.95 g (33.6 mol%) of compound (M-2), 41.98 g (16.0 mol%) of compound (M-5), 35.56 g (16.0 mol%) of (M-8) and 42.28 g (16.0 mol%) of the compound (M-10) was dissolved in 400 g of 2-butanone, and 2,2′-azobisisobutyronitrile (compound (X-6)) was used as an initiator. And the compound (X-6) (26.43 g, 20 mol%) was added to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, this polymerization reaction solution was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-9) (yield 70%). Mw of this polymer (A-9) was 6,900, and Mw / Mn was 1.44. As a result of ¹³ C-NMR analysis, the ratios of the structural units derived from (M-2), (M-5), (M-8), (M-10) and (X-6) were each 34. 9.9 mol%, 14.7 mol%, 16.4 mol%, 21.2 mol% and 13.1 mol%.

[Synthesis Example 18] (Synthesis of polymer (A-10))
65.36 g (33.3 mol%) of compound (M-2), 43.82 g (16.7 mol%) of compound (M-5), 37.11 g (16.7 mol%) of (M-8) and 44.13 g (16.7 mol%) of the compound (M-10) was dissolved in 400 g of 2-butanone, and further, 2,2′-azobisisobutyronitrile (compound (X-7)) was used as an initiator. And the compound (X-7) (30.75 g (16.6 mol%) was added thereto to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, this polymerization reaction solution was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-10) (66% yield). Mw of this polymer (A-10) was 6,800, and Mw / Mn was 1.43. As a result of ¹³ C-NMR analysis, the ratio of the structural units derived from (M-2), (M-5), (M-8), (M-10) and (X-7) was as follows. 34.9 mol%, 15.6 mol%, 17.5 mol%, 19.0 mol% and 13.0 mol%.

[Synthesis Example 19] (Synthesis of polymer (A-11))
74.79 g (38.1 mol%) of compound (M-2), 49.85 g (19.0 mol%) of compound (M-5), 42.23 g (19.0 mol%) of (M-8) and 50.21 g (19.0 mol%) of compound (M-10) was dissolved in 400 g of 2-butanone, and further, 2,2′-azobisisobutyronitrile (compound (X-8) And the compound (X-8) 10.21 g (4.9 mol%) was added thereto to prepare a monomer solution. Meanwhile, 200 g of 2-butanone was charged into a 1000 mL three-necked flask, and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the 2-butanone in the three-necked flask was heated to 80 ° C. while stirring. Next, the above-prepared monomer solution 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 the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by water cooling. Then, this polymerization reaction solution was poured into 4,000 g of methanol to precipitate a white powder, which was then filtered. The filtered white powder was subjected to slurry washing twice using 800 g of methanol, and then filtered. Next, the white powder (copolymer) was dried at 60 ° C. for 17 hours to obtain a polymer (A-11) (yield: 77%). Mw of this polymer (A-11) was 6,700, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the ratios of the structural units derived from (M-2), (M-5), (M-8), (M-10) and (X-8) were 39, respectively. 0.0 mol%, 16.7 mol%, 20.4 mol%, 22.1 mol% and 2.8 mol%.

[Synthesis Example 20] (Synthesis of polymer (A-12))
80.13 g (40.0 mol%) of compound (M-4), 42.82 g (20.0 mol%) of compound (M-9), 61.79 g (40.0 mol%) of compound (M-11) And 2,2′-azobisisobutyronitrile (5 mol% based on all monomers) and t-dodecyl mercaptan (5.3 mol% based on all monomers) as initiator After dissolving in 100 g of glycol monomethyl ether, the mixture was copolymerized for 16 hours while maintaining the reaction temperature at 70 ° C. under a nitrogen atmosphere. After the completion of the polymerization reaction, the polymerization solution was dropped into 1,000 g of n-hexane to coagulate 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 carried out for 8 hours while refluxing at the boiling point. After the completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in 150 g of acetone, and then dropped into 2,000 g of water to coagulate. After drying for a time, a polymer (A-12) in the form of a white powder was obtained (yield: 77%). Mw of the polymer (A-12) was 7,500, and Mw / Mn was 1.88. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-4), (M-9) and p-hydroxystyrene were 40.6 mol%, 20.9 mol%, and 38.5 mol, respectively. Mole%. ^{By 13} C-NMR, it was confirmed that a structure derived from t-dodecyl mercaptan was introduced at the terminal of the polymer.

[Synthesis Example 21] (Synthesis of Polymer (A-13))
80.13 g (38.1 mol%) of compound (M-4), 42.82 g (19.1 mol%) of compound (M-9), 61.79 g (38.1 mol%) of compound (M-11) 2,2′-azobisisobutyronitrile as an initiator (5 mol% based on all monomers including compound (X-1)) and 7.42 g (4.7) of compound (X-1) Mol.) Was dissolved in 100 g of propylene glycol monomethyl ether, and copolymerized under a nitrogen atmosphere at a reaction temperature of 70 ° C for 16 hours. After the completion of the polymerization reaction, the polymerization solution was dropped into 1,000 g of n-hexane to coagulate 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 carried out for 8 hours while refluxing at the boiling point. After the completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in 150 g of acetone, and then dropped into 2,000 g of water to coagulate. After drying for a time, a polymer (A-13) in the form of a white powder was obtained (yield: 77%). Mw of the polymer (A-13) was 7,400, and Mw / Mn was 1.89. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from (M-4), (M-9), p-hydroxystyrene and (X-1) were 38.5 mol% and 19.6, respectively. Mol%, 39.1 mol% and 2.8 mol%.

[Synthesis Example 22] (Synthesis of polymer (A-14))
80.13 g (38.1 mol%) of compound (M-4), 42.82 g (19.1 mol%) of compound (M-9), 61.79 g (38.1 mol%) of compound (M-11) 11.2 g of compound (X-2) and 2,2′-azobisisobutyronitrile (5 mol% based on all monomers including compound (X-2)) as an initiator and 11.20 g of compound (X-2) Mol.) Was dissolved in 100 g of propylene glycol monomethyl ether, and copolymerized under a nitrogen atmosphere at a reaction temperature of 70 ° C for 16 hours. After the completion of the polymerization reaction, the polymerization solution was dropped into 1,000 g of n-hexane to coagulate 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 carried out for 8 hours while refluxing at the boiling point. After the completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in 150 g of acetone, and then dropped into 2,000 g of water to coagulate. After drying for a time, a polymer (A-14) as a white powder was obtained (78% yield). As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-4), (M-9), p-hydroxystyrene and (X-2) were 37.5 mol% and 19.8, respectively. Mol%, 39.2 mol% and 3.5 mol%.

[Synthesis Example 23] (Synthesis of polymer (A-15))
80.13 g (38.1 mol%) of compound (M-4), 42.82 g (19.1 mol%) of compound (M-9), 61.79 g (38.1 mol%) of compound (M-11) 11.2 g of 2,2′-azobisisobutyronitrile (10 mol% based on all monomers including compound (X-3)) as an initiator and 11.37 g (4.7) of compound (X-3) Mol.) Was dissolved in 100 g of propylene glycol monomethyl ether, and copolymerized under a nitrogen atmosphere at a reaction temperature of 70 ° C for 16 hours. After the completion of the polymerization reaction, the polymerization solution was dropped into 1,000 g of n-hexane to coagulate 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 carried out for 8 hours while refluxing at the boiling point. After the completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in 150 g of acetone, and then dropped into 2,000 g of water to coagulate. After drying for a time, a polymer (A-15) in the form of a white powder was obtained (yield: 70%). 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 ratios of structural units derived from (M-4), (M-9), p-hydroxystyrene and (X-3) were 37.0 mol% and 19.9, respectively. Mol%, 39.0 mol% and 4.1 mol%.

[[D] Synthesis of polymer]
157.04 g (70 mol%) of compound (M-3) and 50.41 g (30 mol%) of compound (M-12) were dissolved in 100 g of 2-butanone, and dimethyl 2,2′-azo was used as an initiator. Bisisobutyrate (7 mol% based on all 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 monomer solution prepared above was added dropwise using a dropping funnel over 3 hours. . The polymerization reaction was carried out for 6 hours, with the start of the dropwise addition as the start time of the polymerization reaction. After the completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or lower. After the reaction solution was transferred 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 (60% yield). Mw of the polymer (D-1) was 7,200, and Mw / Mn was 2.00. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from (M-3) and (M-12) were 71.1 mol% and 28.9 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
[B] acid generator, [C] acid diffusion controller, [E] solvent and [F] uneven distribution promotion used in the preparation of radiation-sensitive resin compositions of the following Examples 1 to 8 and Comparative Examples 1 to 6 The agents 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] isothiazole-2-ide 1,1-dioxide C-2: triphenylsulfonium 2-hydroxybenzoate C-3: cyclohexylphenyldiphenylsulfonium 10- Camphor sulfonate 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 acetate acetate E-2: cyclohexanone

[[F] Localization 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, and [C] (C-1) 3 as an acid diffusion controller 0.5 parts by mass, 2,240 parts by mass of (E-1) as a solvent [E] and 960 parts by mass of (E-2) and 100 parts by mass of (F-1) as a [F] uneven distribution promoter. Then, the resulting mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).

[Examples 2 to 8 and Comparative Examples 1 to 6]
The radiation-sensitive resin compositions (J-2) to (J-8) and (CJ-1) were operated in the same manner as in Example 1 except that the components having the types and contents shown in Table 1 below were used. ) To (CJ-6).

<Formation of resist pattern (1)> (Alkaline development)
Using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a composition for forming a lower antireflection film ("ARC66" manufactured by Brewer Science) was applied, and then 205 属 C. For 60 seconds to form a lower antireflection film having an average thickness of 105 nm. Each of the radiation-sensitive resin compositions prepared above was applied onto the lower antireflection film using the spin coater, and subjected to PB at 90 ° C. for 60 seconds. Thereafter, cooling was performed at 23 ° C. for 30 seconds to form a resist film having an average thickness of 90 nm. Next, this resist film was subjected to optical conditions of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON). , 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 aqueous solution of TMAH as an alkali developer, washed with water, and dried to form a positive resist pattern. In forming the resist pattern, the line width formed through a one-to-one line-and-space mask having a target dimension of 40 nm, and the exposure amount formed in a one-to-one line-and-space line width 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 formation of the resist pattern (1) except that the organic solvent was developed using n-butyl acetate instead of the TMAH aqueous solution and washing with water was not performed. Was formed.

<Evaluation>
Each radiation-sensitive resin composition was evaluated by measuring the formed resist pattern according to the following method. The length of the resist pattern was measured using a scanning electron microscope (“CG-4100” manufactured by Hitachi High-Technologies Corporation).

[LWR performance]
Using the above scanning electron microscope, the resist pattern was observed from above the pattern. The line width was measured at an arbitrary point in a total of 50 points, and a 3 sigma value was obtained from the distribution of the measured values, which was defined as LWR performance. The LWR performance indicates that the smaller the value, the better. The LWR performance can be evaluated as “good” when it is 3.00 nm or less, and “bad” when it exceeds 3.00 nm.

[Rectangularity of cross-sectional shape]
The cross-sectional shape of the resist pattern resolved at the optimum exposure dose was observed, and the line width Lb at the middle of the resist pattern and the line width La at the top of the film were measured. At this time, when 0.90 ≦ La / Lb ≦ 1.10.

[Film shrinkage suppression]
Using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron) on the surface of a 12-inch silicon wafer, a composition for forming a lower antireflection film ("ARC66" manufactured by Brewer Science) was applied, and then 205 属 C. For 60 seconds to form a lower antireflection film having an average thickness of 105 nm. Each of the radiation-sensitive resin compositions prepared above was applied onto the lower antireflection film using the spin coater, and subjected to PB at 90 ° C. for 60 seconds. Thereafter, cooling was performed at 23 ° C. for 30 seconds to form a resist film having an average thickness of 90 nm. Next, the resist film was subjected to overall exposure at 70 mJ using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON), and then the film thickness was measured to determine the average thickness A. Subsequently, after performing PEB at 90 ° C. for 60 seconds, the film thickness was measured again to determine the average thickness B. At this time, 100 × (AB) / A (%) was obtained, and this was defined as the film shrinkage ratio due to PEB. The smaller the film shrinkage by PEB, the better the film shrinkage by PEB. If the film shrinkage due to PEB is 19% or less, it can be judged as “good”, and if it exceeds 19%, it can be judged as “poor”.

  In Table 2, "-" indicates that the measurement for the evaluation was not performed.

[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, and [C] 3.6 of (C-1) as an acid diffusion controller. Parts by mass, 4,280 parts by mass of (E-1) as a solvent [E] and 1,830 parts by mass of (E-2) are mixed, and the mixture is filtered through a membrane filter having a pore size of 0.2 [mu] m. Composition (J-9) was prepared.

[Examples 8 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 and the amounts of the components shown in Table 3 below were used.

<Formation of resist pattern (3)> (Alkaline development)
Each of the radiation-sensitive resin compositions described in Table X was applied to the surface of an 8-inch silicon wafer using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Limited) and subjected to PB at 90 ° C. for 60 seconds. . Thereafter, cooling was performed at 23 ° C. for 30 seconds to form a resist film having an average thickness of 50 nm. Next, the resist film was irradiated with an electron beam using a simple electron beam lithography system (model “HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After the irradiation, PEB was performed at 120 ° C. for 60 seconds. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38% by mass aqueous solution of TMAH 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 formation of the resist pattern (1) except that the organic solvent was developed using n-butyl acetate instead of the TMAH aqueous solution and washing with water was not performed. Was formed.

<Evaluation>
The same evaluations as in Examples 1 to 8 were performed on the resist patterns formed using each of the above radiation-sensitive resin compositions. The results are shown in Table 4 below. Regarding the radiation-sensitive resin composition for electron beam exposure, the LWR performance can be evaluated as “good” when the LWR performance is 4.50 nm or less, and “bad” when the LWR performance exceeds 4.50 nm.

  From the results in Tables 2 and 4, the radiation-sensitive resin compositions of the examples show that the WR performance, the rectangularity of the cross-sectional shape and the WR performance were obtained both in the case of ArF exposure and electron beam exposure, and in the case of alkali development and organic solvent development. It turns out that it is excellent in the film shrinkage suppression property. It is known that electron beam exposure and EUV exposure have the same tendency, and it is presumed that the radiation-sensitive resin composition of the example has excellent LWR performance even in the case of EUV exposure. .

  According to the radiation-sensitive resin composition and the method of forming a resist pattern of the present invention, a resist pattern having excellent LWR performance, rectangular cross-sectional shape, and film shrinkage-suppressing properties can be formed. Therefore, they can be suitably used for the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

Claims (5)

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 in the presence of a compound represented by the following formula (1) or a compound represented by the following formula (1-7) .

(In the formula (1), A is —CH ₂ —, an oxygen atom, or —N (R ¹ ) —. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. If it is, L is ^{* 1 -Sn (R 4) (} R 5) -R 6 - - a is ^{_{-CH 2, * 1 -Si (R}} 4) (R 5) -R 6 -, * 1 -P (O) (R ⁴ ) -OR ⁶ -or * ¹ -SR ⁶ -When A is an oxygen atom, L is * ¹ -R ^6- R ⁴ and R ⁵ are Is independently a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms having a carbon atom at the terminal on the bond side, and R ⁶ has 1 to 1 carbon atoms having a carbon atom at the terminal on the A side. is a divalent organic group 20. * ¹ .R ¹ and R ⁶ indicate a site for binding to the a were combined with one another, a nitrogen atom and the nitrogen atom bonded to R ¹ Together with the carbon atoms to focus to form a ring structure ring members 3 to 10 .Z is = ^CR 2 ^{R 3} or .R ² and ^{R 3} is a sulfur atom are each independently a hydrogen atom or a carbon number 1 to It is a monovalent organic group of 20.)

It said ^{R 6} is ^{* 2 -R 7 -, * 2} -CH (CN) -R 7 -, * 2 -C (O) -NH-R 7 -, * 2 -O-C (O) -NH-R ^{7 -, * 2 -O-R} 7 -, * 2 -O-C (O) -R 7 -, * 2 -R 7 -C (O) -, * 2 -C (O) -O-R 7 _{^{-, * 2 -CH 2 -O-}} R 7 -, * 2 -CH 2 -O-C (O) -R 7 - or _{^{* 2 -CH 2 -C (O)}} -O-R 7 - and it is, The radiation-sensitive resin composition according to claim 1, wherein R ⁷ is a divalent hydrocarbon group having 1 to 18 carbon atoms, and * ² represents a site bonded to the carbon atom bonded to Z. Forming a resist film,
Exposing the resist film, and developing the exposed resist film,
A method for forming a resist pattern, comprising forming the resist film using the radiation-sensitive resin composition according to claim 1.   4. The method according to claim 3, wherein in the developing step, a positive resist pattern is formed by developing with an alkaline solution.   4. The method according to claim 3, wherein in the developing step, a negative resist pattern is formed by developing with a liquid containing an organic solvent.