JP6191684B2 - Radiation sensitive resin composition, resist pattern forming method, and polymer - Google Patents

Description

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

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a radiation-sensitive resin composition has been performed. In recent years, with the high integration of integrated circuits, the formation of ultrafine patterns in the submicron region and the quarter micron region has been required. Along with this, the exposure wavelength tends to be shortened from g-line to i-line, KrF excimer laser light, and further ArF excimer laser light. Recently, in addition to excimer laser light, development of lithography technology using EUV, electron beam, etc. has been advanced (Japanese Patent Laid-Open Nos. 2006-171440, 2011-16746, and 2010-204634). No. publication).

  The lithography technique using the EUV or electron beam is expected as a next-generation pattern forming technique capable of forming a pattern in an ultrafine region of 32 nm or less. However, in the exposure using EUV, light having a wavelength of about 150 nm to 350 nm is emitted together with EUV light of 13.5 nm as an out-of-band (OOB). There is an inconvenience that the LWR (Line Width Roughness) performance, resolution, and the like are deteriorated. Therefore, it is required that the resist has excellent out-of-band absorption, and by doing so, it is required to improve LWR performance and resolution. In particular, in the ultrafine region of 32 nm or less where EUV or the like is being applied, LWR performance is an extremely important improvement issue. In EUV and the like, since exposure is performed under vacuum, there is a high demand for reduction of out gas (Out Gas: OG) generated from the resist film at that time.

JP 2006-171440 A JP 2011-16746 A JP 2010-204634 A

  The present invention has been made based on the above circumstances, and its purpose is a radiation-sensitive resin that is excellent in out-of-band absorption, LWR performance, and resolution, and that can suppress outgassing. It is to provide a composition.

（式（ｉ−１）中、Ｌ^１は、それぞれ独立して、単結合、メチレン基、炭素数２〜５のアルキレン基、炭素数３〜１５のシクロアルキレン基、炭素数６〜２０のアリーレン基、又はこれらの基と−Ｏ−及び−ＣＯ−からなる群より選ばれる少なくとも１種とを組み合わせた２価の基である。Ｒ^７は、それぞれ独立して、水素原子、ヒドロキシ基、カルボキシ基、炭素数１〜５の１価の鎖状炭化水素基、炭素数１〜５のアルコキシ基、炭素数２〜５のアルコキシカルボニル基、又は−ＯＲ^Ａ基を末端に有する１価の有機基（ａ）（但し、−ＯＲ^Ａ基は、少なくとも１つのフッ素原子若しくはフッ素化アルキル基を有する炭素原子に結合する）である。Ｒ^Ａは、水素原子又は炭素数１〜２０の１価の有機基である。但し、Ｒ^７のうちの少なくとも１つは有機基（ａ）である。
式（ｉ−２）中、Ｌ^２は、炭素数１〜５のアルカン、炭素数３〜１５の脂環式炭化水素及び炭素数６〜２０のアレーンのいずれかに由来する（ｎ＋１）価の基である。Ｒ^７’は、水素原子、ヒドロキシ基、カルボキシ基、炭素数１〜５の１価の鎖状炭化水素基、炭素数１〜５のアルコキシ基、炭素数２〜５のアルコキシカルボニル基又は上記有機基（ａ）である。ｎは、１〜３の整数である。Ｒ^７’が複数の場合、複数のＲ^７’は同一でも異なっていてもよい。但し、Ｒ^７’のうちの少なくとも１つは有機基（ａ）である。
式（ｐ−１）中、Ｒ^８は、水素原子、フッ素原子、メチル基、トリフルオロメチル基又はヒドロキシメチル基である。Ｒ^９は、炭素数１〜１０の１価の炭化水素基である。Ｒ^１０及びＲ^１１は、それぞれ独立して、炭素数１〜１０の１価の鎖状炭化水素基若しくは炭素数３〜２０の１価の脂環式炭化水素基であるか、又はこれらの基が互いに合わせられこれらが結合する炭素原子と共に構成される環員数３〜２０の環構造を表す。
式（ｐ−２）中、Ｒ^１２は、水素原子、メチル基、トリフルオロメチル基又はヒドロキシメチル基である。Ｒ^１３は、炭素数１〜２０の１価の酸解離性基である。）The invention made in order to solve the above problems is represented by the structural unit represented by the following formula (i-1) (hereinafter also referred to as “structural unit (I-1)”) and the following formula (i-2). At least one selected from the group consisting of structural units (hereinafter also referred to as “structural units (I-2)”), and the following formula (p-1): And a structural unit represented by the following formula (p-2) (hereinafter also referred to as “structural unit (II-2)”). A polymer (hereinafter also referred to as “[A] polymer”), a radiation-sensitive acid generator (hereinafter referred to as “structural unit (II)”) selected from the group consisting of Sensation containing “[B] acid generator”) and an organic solvent (hereinafter also referred to as “[C] organic solvent”) A ray resin composition.

(In formula (i-1), each L ¹ independently represents a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or an arylene having 6 to 20 carbon atoms. Or a divalent group in which these groups and at least one selected from the group consisting of —O— and —CO— are combined, and each R ⁷ independently represents a hydrogen atom, a hydroxy group, or a carboxy group; Group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or a monovalent organic group having an —OR ^A group at its terminal ( ^A ) (wherein the —OR ^A group is bonded to a carbon atom having at least one fluorine atom or fluorinated alkyl group) R ^A is a hydrogen atom or a monovalent organic having 1 to 20 carbon atoms; is a group. However, less of R ⁷ Also one is an organic group (a).
In formula (i-2), L ² is a (n + 1) -valent derived from any one of an alkane having 1 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 15 carbon atoms, and an arene having 6 to 20 carbon atoms. It is a group. R ^{7 ′} is a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. Group (a). n is an integer of 1 to 3. ^'If there are a plurality of a plurality of R ^7' R 7 may be the same or different. However, at least one of R ^{7 ′} is an organic group (a).
In formula (p-1), R ⁸ represents a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ⁹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹⁰ and R ¹¹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents a ring structure having 3 to 20 ring members constituted together with carbon atoms to which they are combined with each other.
In formula (p-2), R ¹² represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ¹³ is a monovalent acid-dissociable group having 1 to 20 carbon atoms. )

  The resist pattern forming method of the present invention includes a step of forming a resist film, a step of exposing the resist film, and a step of developing the exposed resist film, and the resist film is formed into the radiation-sensitive resin composition. To form.

  The polymer of the present invention includes at least one selected from the group consisting of the structural unit represented by the formula (i-1) and the structural unit represented by the formula (i-2), and the formula (p- 1) and at least one selected from the group consisting of the structural unit represented by the formula (p-2).

  Here, the “organic group” refers to a group containing at least one carbon atom.

  According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist film having excellent out-of-band absorbability while suppressing the generation of OG from the resist film. A small and high resolution resist pattern can be formed. Moreover, the polymer of this invention can be used suitably as a component of the said radiation sensitive resin composition. Therefore, they can be suitably used for forming a fine resist pattern in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

  The radiation sensitive resin composition contains a [A] polymer, a [B] acid generator, and a [C] organic solvent. The radiation-sensitive resin composition may contain a [D] acid diffusion controller as a suitable component, 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 (I) and a structural unit (II). In the radiation-sensitive resin composition, the [A] polymer has both the structural unit (I) having the specific structure including the specific group (a) and the structural unit (II) including an acid dissociable group. As a result, the LWR performance and resolution are excellent, and generation of OG from the formed resist film can be suppressed. The [A] polymer having the above specific structure can absorb OOB generated during exposure. In addition, the [A] polymer can moderately adjust the solubility in a developer and the like, and in addition, has a structural unit (I) and has a relatively high glass transition temperature. [B] Diffusion of the acid generated from the acid generator or the like can be moderately suppressed. By these, according to the said radiation sensitive resin composition, LWR performance and resolution can be improved. In addition, the radiation sensitive resin composition has a relatively high glass transition temperature of the polymer [A], so that permeation of volatile components generated from the formed resist film can be suppressed, and outgassing can be reduced. Can do.

  [A] In addition to the structural unit (I) and the structural unit (II), the polymer includes the structural unit (III) represented by the above formulas (ii-1) to (ii-4), a lactone structure, and a cyclic structure. It may have a structural unit (IV) containing at least one selected from the group consisting of a carbonate structure and a sultone structure, and may have other structural units other than these. [A] The polymer may have two or more of these structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is at least one structural unit selected from the group consisting of the structural unit (I-1) and the structural unit (I-2). [A] The polymer has a structural unit (I) containing a specific organic group (a) and containing an acenaphthylene skeleton or a 5-membered ring imide skeleton, so that it can absorb OOB, a developer, etc. It is possible to appropriately adjust the solubility in the glass and to increase the glass transition temperature. As a result, generation of OG from the resist film formed from the radiation-sensitive resin composition can be suppressed, and the LWR performance and resolution are excellent due to the synergistic effect with the structural unit (II). Can be.

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

In formula (i-1), each L ¹ independently represents a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or an arylene having 6 to 20 carbon atoms. Or a divalent group in which these groups are combined with at least one selected from the group consisting of —O— and —CO—. R ⁷ each independently represents a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkoxycarbonyl group having 2 to 5 carbon atoms. Or a monovalent organic group (a) having a terminal —OR ^A group (provided that the —OR ^A group is bonded to a carbon atom having at least one fluorine atom or a fluorinated alkyl group). R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. However, at least one of R ⁷ is an organic group (a).

Examples of the alkylene group having 2 to 5 carbon atoms represented by L ¹ include an ethylene group, a linear or branched propylene group, a butylene group, and a pentylene group.

Examples of the cycloalkylene group having 3 to 15 carbon atoms represented by L ¹ include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cyclodecylene group, a norbornylene group, and an adamantylene group. Can be mentioned.

Examples of the arylene group having 6 to 20 carbon atoms represented by L ¹ include a phenylene group, a tolylene group, a xylylene group, a naphthylene group, and an anthrylene group.

As the divalent group in which the single bond represented by L ¹ , a methylene group, an alkylene group, a cycloalkylene group, an arylene group and at least one selected from the group consisting of —O— and —CO— are combined, For example, -O-, -CO-, -COO-, methyleneoxy group, methylenecarbonyl group, methylenecarbonyloxy group, methyleneoxycarbonyl group, alkyleneoxy group, alkylenecarbonyl group, alkylenecarbonyloxy group, alkyleneoxycarbonyl group, Cycloalkyleneoxy group, cycloalkylenecarbonyl group, cycloalkylenecarbonyloxy group, cycloalkyleneoxycarbonyl group, aryleneoxy group, arylenecarbonyl group, arylenecarbonyloxy group, aryleneoxycarbonyl group, methyleneoxymethyle Group, methylenecarbonylmethylene group, methyleneoxycarbonylmethylene group, alkyleneoxyalkylene group, alkylenecarbonylalkylene group, alkyleneoxycarbonylalkylene group, cycloalkyleneoxycycloalkylene group, cycloalkylenecarbonylcycloalkylene group, cycloalkyleneoxycarbonylcycloalkylene A group, an aryleneoxyarylene group, an arylenecarbonylarylene group, an aryleneoxycarbonylarylene group, an alkyleneoxyarylene group, and the like.

L ¹ is preferably a single bond or a methylene group, and more preferably a single bond, from the viewpoint that the glass transition temperature of the [A] polymer is higher.

Examples of the monovalent chain hydrocarbon group having 1 to 5 carbon atoms represented by R ⁷ include:
Alkyl groups such as methyl group, ethyl group, linear or branched propyl group, butyl group and pentyl group;
An alkenyl group such as an ethenyl group, a linear or branched propenyl group, a butenyl group, a pentenyl group;
Examples include ethynyl groups, propynyl groups, linear or branched butynyl groups, alkynyl groups such as pentynyl groups, and the like.

As a C1-C5 alkoxy group represented by said R < ⁷ >, a methoxy group, an ethoxy group, a linear or branched propoxy group, a butoxy group, a pentoxy group etc. are mentioned, for example.

Examples of the alkoxycarbonyl group having 2 to 5 carbon atoms represented by R ⁷ include a methoxycarbonyl group, an ethoxycarbonyl group, a linear or branched propoxycarbonyl group, and a butoxycarbonyl group.

The monovalent organic group (a) having an —OR ^A group represented by R ⁷ at the end (provided that the —OR ^A group is bonded to a carbon atom having at least one fluorine atom or a fluorinated alkyl group). Although it does not specifically limit as long as it has this structure, The group (henceforth "group (a ')") represented by a following formula (a') is preferable.

In the formula (a ′), R ^{1 to} R ⁶ are each independently a hydrogen atom, a halogen atom, or a C 1-5 perfluoroalkyl group. However, at least one of R ^{1 to} R ⁶ is a fluorine atom or a C 1-5 perfluoroalkyl group. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * Indicates a site binding to ^{L 2} in ^{L 1} or the formula in the above formula (i-1) (i- 2).

Examples of the halogen atom represented by R ^{1 to} R ⁶ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the perfluoroalkyl group having 1 to 5 carbon atoms represented by R ^{1 to} R ⁶ include a trifluoromethyl group, a pentafluoroethyl group, a linear or branched heptafluoropropyl group, and nonafluorobutyl. Group, undecafluoropentyl group and the like.

As the R ¹ to R ^6, a fluorine atom, a perfluoroalkyl group are preferable, and fluorine atom is more preferable.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^A include, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms and a hetero atom between carbon-carbon of the hydrocarbon group. And a hetero atom-containing group containing a group, a group in which part or all of the hydrogen atoms of the hetero atom-containing group are substituted with a substituent, and the like.

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

  Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, and a phosphorus atom.

  Examples of the group having a heteroatom include —O—, —CO—, —NH—, —S—, and a combination thereof.

  Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group and acyl group.

R ^A is preferably a hydrogen atom from the viewpoint that the solubility of the [A] polymer in a developer or the like can be adjusted more appropriately.

  Examples of the organic group (a) include a methylfluoromethylhydroxymethyl group, a methyldifluoromethylhydroxymethyl group, a methyltrifluoromethylhydroxymethyl group, a di (fluoromethyl) hydroxymethyl group, and a di (trifluoromethyl) hydroxymethyl. Group, trifluoromethylpentafluoroethylhydroxymethyl group, di (pentafluoroethyl) hydroxymethyl group, di (trifluoromethyl) methoxymethyl group, di (trifluoromethyl) acetoxymethyl group and the like. Among these, a di (trifluoromethyl) hydroxymethyl group and a methyltrifluoromethylhydroxymethyl group are preferable, and a di (trifluoromethyl) hydroxymethyl group is more preferable.

R ⁷ is preferably a hydrogen atom or an organic group (a), more preferably a hydrogen atom, a di (trifluoromethyl) hydroxymethyl group or a methyltrifluoromethylhydroxymethyl group, a hydrogen atom or di (trifluoromethyl) hydroxy. More preferred is a methyl group.

  The number of the organic groups (a) in the structural unit (I-1) is preferably 1 to 4 from the viewpoint of appropriately adjusting the solubility of the [A] polymer in a developer or the like. More preferably, one or two is more preferable, and one is particularly preferable.

As a group in which L ¹ and R ⁷ are combined, a hydrogen atom or an organic group (a) is preferable, and a hydrogen atom, a di (trifluoromethyl) hydroxymethyl group, a methyltrifluoromethylhydroxymethyl group, or a di (trifluoromethyl). ) A hydroxyethyl group is more preferable, and a hydrogen atom, a di (trifluoromethyl) hydroxymethyl group, and a methyltrifluoromethylhydroxymethyl group are more preferable.

  Examples of the structural unit (I-1) include structural units represented by the following formulas (1-1-1) to (1-1-15) (hereinafter referred to as “structural units (I-1-1) to ( I-1-15) ”) and the like.

  Among these, the structural unit (I-1-1), the structural unit (I-1-3), the structural unit (I-1-13), and the structural unit (I-1-15) are preferable.

(Structural unit (I-2))
The structural unit (I-2) is a structural unit represented by the following formula (i-2).

In the above formula (i-2), L ² is an (n + 1) valence derived from any one of an alkane having 1 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 15 carbon atoms, and an arene having 6 to 20 carbon atoms. It is the basis of. R ^{7 ′} is a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. Group (a). n is an integer of 1 to 3. ^'If there are a plurality of a plurality of R ^7' R 7 may be the same or different. However, at least one of R ^{7 ′} is an organic group (a).

Examples of the (n + 1) -valent group derived from an alkane having 1 to 5 carbon atoms represented by L ² include, for example, removing (n + 1) hydrogen atoms from an alkane such as methane, ethane, propane, butane, and pentane. And the like.

Examples of the (n + 1) -valent group derived from the alicyclic hydrocarbon having 3 to 15 carbon atoms represented by L ² include cyclopropane such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclodecane, norbornane, and adamantane. And a group obtained by removing (n + 1) hydrogen atoms from an alkane.

Examples of the (n + 1) -valent group derived from an arylene having 6 to 20 carbon atoms represented by L ² include (n + 1) groups from an arene such as benzene, toluene, xylene, mesitylene, naphthalene, anthracene, and phenanthrene. Examples include a group excluding a hydrogen atom.

Examples of each group represented by R ^{7 ′} include the same groups as those exemplified as the respective groups represented by R ⁷ in the formula (i-1).

  The number of the organic groups (a) in the structural unit (I-2) is preferably 1 or 2 from the viewpoint of more appropriately adjusting the solubility of the [A] polymer in a developer or the like. Is more preferable.

  N is preferably 1 or 2, and more preferably 1.

  Examples of the structural unit (I-2) include structural units represented by the following formulas (1-2-1) to (1-2-8) (hereinafter referred to as “structural units (I-2-1) to ( I-2-8) ”) and the like.

  Among these, the structural unit (I-2-1) and the structural unit (I-2-2) are preferable, and the structural unit (I-2-1) is more preferable.

  As a minimum of the content rate of structural unit (I), 5 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 10 mol% is more preferable, and 15 mol% is more preferable. As an upper limit of the content rate of structural unit (I), 80 mol% is preferable, 50 mol% is more preferable, and 30 mol% is further more preferable. By setting the content ratio of the structural unit (I) within the above range, the LWR performance and resolution of the radiation-sensitive resin composition can be further improved, and the outgas from the formed resist film is further suppressed. Can be made.

  Examples of the monomer that gives the structural unit (I) include compounds represented by the following formulas (1-1-1m) to (1-2-8m) (hereinafter referred to as “compounds (1-1-1m) to ( 1-2-8m) ”) and the like.

  Among these, the compound (1-1-1m), the compound (1-1-3m), the compound (1-1-13m), the compound (1-1-15m), the compound (1-2-1m), The compound (1-2-2m) is preferable, and the compound (1-1-1m), the compound (1-1-3m), the compound (1-1-13m), the compound (1-1-15m), and the compound (1 2-1 m) is more preferable.

Among the compounds giving the structural unit (I-1), those in which L ¹ is a single bond and R ⁷ is a group (a ′) ( ^RA is a hydrogen atom) are, for example, acenaphthenes such as 5-bromoacenaphthene A bromo compound of a compound having a skeleton and a carbonyl compound having a fluorine atom such as hexafluoroacetone are reacted in a solvent such as diethyl ether in the presence of n-butyllithium to have a group (a ′). An acenaphthene compound is obtained, and then this compound is reacted with N-bromosuccinimide (NBS) in a solvent such as chlorobenzene and then with sodium methoxide in a solvent such as tetrahydrofuran (THF). Can be synthesized. Further, such a compound having a group (a ′) in which R ^A is a hydrogen atom is obtained by di-tert-dicarbonate in a solvent such as THF in the presence of a base such as 4- (dimethylamino) pyridine. By reacting with butyl, it can be converted into a compound in which R ^A of the group (a ′) is a tert-butoxycarbonyl group.
Among the compounds giving the structural unit (I-2), those in which L ² is a group derived from an arene such as a benzenediyl group and R ^{7 ′} is a group (a ′) (R ^A is a hydrogen atom) The bromo compound of an aromatic amine compound such as p-bromoaniline is protected with an amino group using di-tert-butyl dicarbonate and the like, and then converted into a Grignard reagent using magnesium, and a fluorine atom such as hexafluoroacetone is added. After reacting in a solvent such as THF with a carbonyl compound having an amino group, the amino group is deprotected to obtain an aromatic amine compound having a group (a ′). Next, this compound and maleic anhydride are combined with THF. It can synthesize | combine by making it react in solvents, such as.

[Structural unit (II)]
The structural unit (II) is at least one structural unit selected from the group consisting of the structural unit (II-1) and the structural unit (II-2). The said radiation sensitive resin composition can improve pattern formation property because a [A] polymer has structural unit (II) containing an acid dissociable group, and a synergistic effect with structural unit (I) Thus, the LWR performance and the resolution can be improved. The “acid-dissociable group” refers to a group that replaces a hydrogen atom of a carboxy group, a phenolic hydroxyl group, or the like and dissociates by the action of an acid.

(Structural unit (II-1))
The structural unit (II-1) is a structural unit represented by the following formula (p-1). ^-CR 9 ^R 10 ^{R 11} in formula (p-1) is an acid-dissociable group.

In the formula (p-1), R ⁸ represents a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ⁹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹⁰ and R ¹¹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents a ring structure having 3 to 20 ring members constituted together with carbon atoms to which they are combined with each other.

R ⁸ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1).

Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ⁹ include:
C1-C10 alkyl groups, such as a methyl group, an ethyl group, a propyl group, a butyl group;
An alkenyl group having 2 to 10 carbon atoms such as an ethenyl group, a propenyl group, and a butenyl group;
A monovalent chain hydrocarbon group having 1 to 10 carbon atoms such as an alkynyl group having 2 to 10 carbon atoms such as an ethynyl group, a propynyl group, or a butynyl group;
A cycloalkyl group having 3 to 10 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group;
Monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms such as cycloalkenyl group having 3 to 10 carbon atoms such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group and norbornenyl group;
Aryl groups having 6 to 10 carbon atoms such as phenyl group, tolyl group, xylyl group, mesityl group and naphthyl group;
Examples thereof include monovalent aromatic hydrocarbon groups such as aralkyl groups having 7 to 10 carbon atoms such as benzyl group, phenethyl group, and phenylpropyl group.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ¹⁰ and R ¹¹ include the same groups as the monovalent chain hydrocarbon group exemplified as R ⁹ above. .
Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹⁰ and R ¹¹ include:
A cycloalkyl group having 3 to 20 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group;
Examples thereof include a cycloalkenyl group having 3 to 20 carbon atoms such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group.

  Examples of the ring structure having 3 to 20 ring members constituted by the carbon atoms to which these groups are combined and bonded to each other include, for example, cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, norbornane structure, adamantane structure And cycloalkene structures such as cycloalkane structure, cyclopropene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure, norbornene structure and the like.

  Examples of the structural unit (II-1) include structural units represented by the following formulas (2-1-1) to (2-1-7) (hereinafter referred to as “structural units (II-1-1) to ( II-1-7) ”) and the like.

In the above formulas (2-1-1) to (2-1-7), R ^{8 to} R ¹¹ have the same meaning as the above formula (p-1).

  Among these, the structural unit (II-1-2) and the structural unit (II-1-3) are preferable, and the structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate, 1-alkyl-1- A structural unit derived from cyclopentyl (meth) acrylate is more preferable, a structural unit derived from 2-ethyl-2-adamantyl (meth) acrylate, and a structural unit derived from 1-ethyl-1-cyclopentyl (meth) acrylate is more preferable. .

(Structural unit (II-2))
The structural unit (II-2) is a structural unit represented by the following formula (p-2).

In the formula (p-2), R ¹² is a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ¹³ is a monovalent acid-dissociable group having 1 to 20 carbon atoms.

R ¹² is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (II-2).

The monovalent acid dissociable group represented by R ¹³ is not particularly limited as long as it has acid dissociability, and examples thereof include a group represented by the following formula (b).

In said formula (b), ^Ra is a C1-C20 monovalent hydrocarbon group. R ^b and R ^c are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other. It represents a ring structure having 3 to 20 carbon atoms that is configured together with the carbon atom to which they are bonded. However, when R ^b oxy hydrocarbon group, R ^c may be a hydrogen atom.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^{a to} R ^c include, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent hydrocarbon having 3 to 20 carbon atoms. Alicyclic hydrocarbon groups, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, and the like.

Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by R ^b and R ^c include, for example,
A monovalent oxy-chain hydrocarbon group having 1 to 20 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, an ethenyloxy group;
C3-C20 such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group, norbornyloxy group, adamantyloxy group, cyclohexylmethyloxy group, cyclohexylethyloxy group, cyclohexenyloxy group, etc. Monovalent oxyalicyclic hydrocarbon group;
Examples thereof include monovalent oxyaromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenoxy group, tolyloxy group and naphthyloxy group.

  Examples of the ring structure having 3 to 20 carbon atoms, which is constituted together with the carbon atoms to which these groups are combined with each other, include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a norbornane structure, an adamantane structure And oxacycloalkane structures such as oxacyclobutane structure, oxacyclopentane structure, and oxacyclohexane structure.

  As the structural unit (II-2), for example, structural units represented by the following formulas (2-2-1) to (2-2-6) (hereinafter referred to as “structural units (II-2-1) to ( II-2-6) ")) and the like.

In the above formulas (2-2-1) to (2-2-6), R ¹² has the same meaning as the above formula (p-2).

  Of these, the structural unit (II-2-1) is preferable.

  As a minimum of the content rate of structural unit (II), 10 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 20 mol% is more preferable, and 30 mol% is further more preferable. As an upper limit of the content rate of structural unit (I), 80 mol% is preferable, 70 mol% is more preferable, and 60 mol% is further more preferable. By making the content rate of structural unit (I) into the said range, the LWR performance and resolution of the said radiation sensitive resin composition can be improved more.

[Structural unit (III)]
The structural unit (III) is a group consisting of structural units represented by the following formulas (ii-1) to (ii-4) (hereinafter also referred to as “structural units (III-1) to (III-4)”). And at least one structural unit selected from the above. [A] When the polymer has the structural unit (III), the radiation-sensitive resin composition can improve sensitivity, particularly sensitivity to EUV or electron beam.

In the above formulas (ii-1) to (ii-4), R ^C each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
In the above formulas (ii-1) to (ii-3), a is independently an integer of 1 to 3. R ^B is each independently an alkyl group having 1 to 5 carbon atoms. b is an integer of 0-4 each independently. If R ^B is plural, or different in each of the plurality of R ^B identical. However, 1 ≦ a + b ≦ 5 is satisfied.
In the above formula (ii-4), L ³ and L ⁴ each independently represent a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or 6 to 6 carbon atoms. 20 arylene groups, or a divalent group in which these groups are combined with at least one selected from the group consisting of —O— and —CO—. R ¹⁴ represents a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. (A). c is an integer of 1-5. L ⁴ and when ^{R 14} is plural, respectively, may be different in each of the plurality of ^{L 4} and ^{R 14} are the same. However, at least one of R ¹⁴ is the organic group (a).

Examples of the alkyl group having 1 to 5 carbon atoms represented by R ^B and R ^C, for example, a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, a pentyl group.

From the viewpoint of copolymerization of the monomer that gives the structural unit (III), R ^C is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.
As the ^{R B,} a methyl group is preferred.
As said a, 1 or 2 is preferable and 1 is more preferable.
As said b, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.

The alkylene group having 2 to 5 carbon atoms, the cycloalkylene group having 3 to 15 carbon atoms, the arylene group having 6 to 20 carbon atoms, or these groups and -O- and -CO- represented by the above L ³ and L ⁴ Examples of the divalent group in combination with at least one selected from the group consisting of include the same groups as the groups exemplified as L ^{1 in} the above formula (i-1).

As the monovalent chain hydrocarbon group having 1 to 5 carbon atoms, the alkoxy group having 1 to 5 carbon atoms, the alkoxycarbonyl group having 2 to 5 carbon atoms and the organic group (a) represented by R ¹⁴ , For example, the group similar to each group illustrated as R < ⁷ > of said Formula (i-1), etc. are mentioned.

  Examples of the structural unit (III) include structural units represented by the following formulas (3-1-1) to (3-4-2) (hereinafter referred to as “structural units (III-1-1) to (III- 4-2) ") and the like.

In the above formulas (3-1-1) to (3-4-2), R ^C has the same meaning as the above formulas (ii-1) to (ii-4).

As the structural unit (III), from the viewpoint of further increasing the sensitivity of the radiation-sensitive resin composition, the structural unit (III-1) and the structural unit (III-4) are preferable, and the structural unit (III-4) is more preferable. preferable.
Among the structural units represented by the above formula, the structural unit (III-1-1), the structural unit (III-2-1), the structural unit (III-3-1), and the structural unit (III-4) -1) is preferable, the structural unit (III-1-1) and the structural unit (III-4-1) are more preferable, and the structural unit (III-1-1) is more preferable.

  As a content rate of structural unit (III), 5 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 10 mol%-70 mol% are more preferable, 20 mol% -60 mol% is more preferable. By making the content rate of structural unit (III) into the said range, the said radiation sensitive resin composition can raise more sensitivity, especially the sensitivity to EUV and an electron beam.

  As the structural unit (III-1), for example, acetoxystyrene or the like is used for polymerization instead of using a monomer that gives it such as hydroxystyrene, and the acetoxy group of the obtained polymer is hydrolyzed to a hydroxy group. It may be obtained by conversion.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. In the radiation-sensitive resin composition, the [A] polymer further has the structural unit (IV), whereby the solubility in the developer can be adjusted, and as a result, the LWR performance and the resolution are further improved. be able to. Moreover, the said radiation sensitive resin composition can improve the adhesiveness to the board | substrate etc. of the resist pattern formed because a [A] polymer further has structural unit (IV).

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

In the above formula, R ^L1 represents a hydrogen atom, a fluorine atom, a methyl group, a hydroxymethyl group, or a trifluoromethyl group.

  Among these, the structural unit (IV) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, or a structural unit containing a γ-butyrolactone structure, and norbornane lactone-yl (meth) acrylate. More preferred are structural units derived from γ-butyrolactone-yl (meth) acrylate.

  As a content rate of structural unit (IV), 5 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 10 mol%-60 mol% are more preferable, 20 mol% More preferred is ˜50 mol%. By making the content rate of structural unit (IV) into the said range, the LWR performance and resolution of the said radiation sensitive resin composition can further be improved.

<Other structural units>
[A] The polymer may have other structural units in addition to the structural units (I) to (IV) as long as the effects of the present invention are not impaired. As other structural units, for example, structural units derived from aromatic compounds having a polymerizable group such as styrene, vinylnaphthalene, acenaphthylene, etc. (excluding those corresponding to structural units (I) and (II)) ), A structural unit containing a fluorine atom, a structural unit containing a polar group such as a hydroxyl group, a carboxy group, and a kent group (however, excluding those corresponding to the structural unit (I) and the structural unit (II)).

  As a content rate of the said other structural unit, 30 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 20 mol% or less is more preferable.

  [A] The content of the polymer is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 75% by mass or more based on the total solid content of the radiation-sensitive resin composition. The radiation sensitive resin composition may contain one or more [A] polymers.

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

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

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

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionitrile) and the like. Two or more of these initiators may be mixed and used.

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

  [A] As a weight average molecular weight (Mw) by the gel permeation chromatography (GPC) of a polymer, 1,000-100,000 are preferable, 1,000-50,000 are more preferable, 1,000-30 1,000 is more preferable, and 1,000 to 15,000 is particularly preferable. [A] By making Mw of a polymer into the said range, it can further improve to the suppression ability of OG of the resist film formed from the said radiation sensitive resin composition.

  [A] The ratio (Mw / Mn) between the Mw of the polymer and the number average molecular weight (Mn) is usually 1 to 5, and preferably 1 to 3. [A] By making Mw / Mn of a polymer into the said range, it can further improve to the suppression ability of OG of the resist film formed from the said radiation sensitive resin composition.

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

  [A] The content of the low molecular weight portion of the polymer is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and further preferably 0.1% by mass or less. [A] By setting the content of the low molecular weight portion of the polymer in the above range, the LWR performance and resolution of the radiation-sensitive resin composition can be further improved, and from the resist film to be formed The generation of OG can be further suppressed. The low molecular weight part of the polymer means a part having a molecular weight of 1,000 or less.

  In addition, the content (mass%) of the low molecular weight part (part with a molecular weight of 1,000 or less) of the polymer in this specification uses an HPLC column (Intersil ODS-25 μm, 4.6 mmφ × 250 mm, GL Sciences Inc.). , Flow rate 1.0 mL / min, elution solvent acrylonitrile / 0.1% by mass phosphoric acid aqueous solution, sample concentration 1.0% by mass, sample injection amount 100 μL, high performance liquid chromatography (HPLC) using a differential refractometer as a detector The value measured by

<[B] Acid generator>
[B] The acid generator is a compound that generates an acid upon irradiation with radiation. Due to the action of the acid, the acid dissociable groups present in the [A] polymer are dissociated, and polar groups such as carboxy groups and phenolic hydroxyl groups are generated, so that the solubility of the [A] polymer in the developer changes. As a result, a resist pattern can be formed. The acid generator contained in the radiation-sensitive resin composition was incorporated as part of the polymer even in the form of a compound as described later (hereinafter referred to as “[B] acid generator” as appropriate). It may be in the form or both forms.

  [B] Examples of the acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like. Of these, onium salt compounds are preferred.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like. Of these, sulfonium salts, tetrahydrothiophenium salts, and iodonium salts are preferable, and sulfonium salts and tetrahydrothiophenium salts are more preferable.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldipheny Sulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2 -Yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, trifer Rusulfonium 2- (1-adamantyl) -1,1-difluoroethanesulfonate, triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate, triphenylsulfonium 6 -(1-adamantylcarbonyloxy) -1,1,2-trifluorobutane-1-sulfonate, triphenylsulfonium 2- (4-oxo-1-adamantylcarbonyloxy) -1,1,3,3,3- Pentafluoropropane-1-sulfonate, triphenylsulfonium 2- (1-adamantylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate, triphenylsulfonium 2-bicyclo [2.2. 1] Hept-2-yl-1,1-diph Luoethane sulfonate and the like can be mentioned.

  Of these, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium 2- (1-adamantyl) -1,1 -Difluoroethanesulfonate, triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1,2,2-tetrafluorohexane-1-sulfonate, triphenylsulfonium 6- (1-adamantylcarbonyloxy) -1,1, 2-trifluorobutane-1-sulfonate, triphenylsulfonium 2- (4-oxo-1-adamantylcarbonyloxy) -1,1,3,3,3-pentafluoropropane 1-sulfonate, triphenylsulfonium 2- (1-adamantylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1-difluoroethanesulfonate is preferred, and triphenylsulfonium 2- (1-adamantylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate, triphenylsulfonium nonafluoro- n-butanesulfonate is more preferred.

Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Ni-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Torahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate , 1- (3,5-dimethyl-4 Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxy Phenyl) tetrahydrothiophenium camphorsulfonate and the like.
Of these, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro -N-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoro Ethanesulfonate and 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate are preferred.

  [B] As content of the acid generator, when the [B] acid generator is a [B] acid generator, from the viewpoint of ensuring sensitivity and developability as a resist, [A] 100 parts by mass of the polymer Is preferably from 0.1 parts by weight to 40 parts by weight, more preferably from 1 part by weight to 30 parts by weight, and even more preferably from 3 parts by weight to 25 parts by weight. [B] When the content of the acid generator is less than 0.1 parts by mass, the sensitivity of the radiation-sensitive resin composition tends to decrease. On the other hand, when the content exceeds 40 parts by mass, transparency to radiation decreases. Therefore, it tends to be difficult to obtain a desired resist pattern. [B] The acid generator may be used alone or in combination of two or more.

<[C] Organic solvent>
[C] The organic solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer, [B] acid generator and optional components. For example, alcohol solvents, ether solvents, ketone organic solvents Amide solvents, ester solvents, hydrocarbon solvents and the like.

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

As an ether solvent, for example,
Dipropyl ether, diisopropyl ether, butyl methyl ether, butyl ethyl ether, butyl propyl ether, dibutyl ether, diisobutyl ether, tert-butyl-methyl ether, tert-butyl ethyl ether, tert-butyl propyl ether, di-tert-butyl ether, Dipentyl ether, diisoamyl ether, cyclopentyl methyl ether, cyclohexyl methyl ether, cyclopentyl ethyl ether, cyclohexyl ethyl ether, cyclopentyl propyl ether, cyclopentyl-2-propyl ether, cyclohexyl propyl ether, cyclohexyl-2-propyl ether, cyclopentyl butyl ether, cyclopentyl- tert-butyl ether, cyclohex Butyl ether, cyclohexyl -tert- butyl ether, anisole, diethyl ether, chain ether solvent diphenyl ether;
Examples thereof include cyclic ether solvents such as THF 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- Chain ketone solvents such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, 2,4-pentanedione, acetonyl acetone, acetophenone;
Examples thereof include cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone.

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

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

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

  Among these, ester solvents and ketone solvents are preferable, polyhydric alcohol partial ether acetate solvents and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are more preferable. These [C] organic solvents may be used individually by 1 type, and may use 2 or more types together.

<[D] Acid diffusion controller>
[D] The acid diffusion controller is a component that controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure and suppresses an undesirable chemical reaction in the unexposed area. When the radiation sensitive resin composition contains the [D] acid diffusion controller, the storage stability of the resulting radiation sensitive resin composition is further improved, and the resolution as a resist is further improved. In addition, it is possible to suppress a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing, and a composition having extremely excellent process stability can be obtained. As the inclusion form of the [D] acid diffusion controller in the radiation-sensitive resin composition, even in the form of a compound described later (hereinafter referred to as “[D] acid diffusion controller” as appropriate), as a part of the polymer Either the built-in form or both forms may be used.

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

  Examples of the amine compound include mono (cyclo) alkylamines such as n-pentylamine; di (cyclo) alkylamines such as di-n-pentylamine; tri (cyclo) alkylamines such as tri-n-pentylamine; Substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 4,4 '-Diaminobenzophenone, 4,4'-diaminodiphenylamine, 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4- Aminophenyl) -2- (3-hydroxyphenyl) propane, -(4-aminophenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4 -Aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxa Linol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine, triethanolamine and the like can be mentioned. Among these, tri (cyclo) alkylamines are preferable, and tri-n-pentylamine is more preferable.

  Examples of amide group-containing compounds include Nt-butoxycarbonyl group-containing amino compounds, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, Examples thereof include benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

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

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, N- (t-amyloxycarbonyl) -4-hydroxypiperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, N- (t-butoxycarbonyl) -2-hydroxymethylpyrrolidine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- ( N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane, N- (t-butoxycarbonyl) -2-phenylbenzimidazole and the like. It is done. Among these, N- (t-amyloxycarbonyl) -4-hydroxypiperidine, N- (t-butoxycarbonyl) -2-hydroxymethylpyrrolidine, N- (t-butoxycarbonyl) -2-phenylbenzimidazole, 2,4,5-triphenylimidazole is preferred.

  Further, as the [D] acid diffusion control agent, a photodisintegratable base that is exposed to light and generates a weak acid by exposure can also be used. This photodegradable base exhibits a high acid scavenging function by an anion in the unexposed area, functions as a quencher, and captures the acid diffusing from the exposed area. That is, since it functions as a quencher only in the unexposed area, the contrast of the deprotection reaction is improved, and as a result, the resolution can be further improved. As an example of the photodegradable base, there is an onium salt compound that is decomposed by exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (4-1) and an iodonium salt compound represented by the following formula (4-2).

The formula (4-1) and formula ^(4-2), independently R 15 ^{to R 19} are each a hydrogen atom, an alkyl group, an alkoxy group, hydroxy group, is a halogen atom or _-SO 2 -R ^D . R ^D is an alkyl group, a cycloalkyl group, an alkoxy group or an aryl group. Z ⁻ is OH ⁻ , R ²¹ —COO ⁻ , R ^E —SO ₂ —N ^— R ²¹ , R ²¹ —SO ₃ ^— or an anion represented by the following formula (4-a). R ²¹ is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group, cycloalkyl group, aryl group and aralkyl group may be substituted. R ^E is a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms which may have a substituent. Some or all of the hydrogen atoms of the alkyl group and cycloalkyl group may be substituted with fluorine atoms. However, when Z ⁻ is R ²¹ —SO ₃ ^— , a fluorine atom is not bonded to a carbon atom to which SO ₃ ^— is bonded.

In the formula (4-a), R ^20, a part or all of the hydrogen atoms linear or branched alkyl group having 1 to 12 carbon atoms which may be substituted by a fluorine atom, or carbon atoms 1 -12 linear or branched alkoxy groups. u is an integer of 0-2.

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

  Among these, triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are preferable.

  [D] The content of the acid diffusion controller is 0 to 10 parts by mass with respect to 100 parts by mass of the polymer [A] when the [D] acid diffusion controller is a [D] acid diffusion controller. Is preferable, and 0.5 to 7 parts by mass is more preferable. [D] When the content of the acid diffusion controller exceeds the above upper limit, the sensitivity as a resist tends to decrease. [D] The acid diffusion inhibitor may be used alone or in combination of two or more.

<Other optional components>
The radiation-sensitive resin composition may contain, as other optional components, for example, a fluorine atom-containing polymer, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like. The said radiation sensitive resin composition may contain 1 type (s) or 2 or more types of other arbitrary components, respectively.

(Fluorine atom-containing polymer)
The radiation sensitive resin composition may further contain a fluorine atom-containing polymer (except for those corresponding to the [A] polymer). When the radiation-sensitive resin composition contains a fluorine atom-containing polymer, when the resist film is formed, the distribution is unevenly distributed near the resist film surface due to the oil-repellent characteristics of the fluorine atom-containing polymer in the resist film. It is possible to prevent the acid generator, the acid diffusion controller and the like from being eluted into the immersion medium during immersion exposure. Further, due to the water-repellent characteristics of this fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, the said radiation sensitive resin composition can form the resist film suitable for an immersion exposure method by further containing a fluorine atom containing polymer.

  The fluorine atom-containing polymer is not particularly limited as long as it is a polymer having a fluorine atom, but the fluorine atom content (% by mass) is higher than the [A] polymer of the radiation-sensitive resin composition. Is preferred. Examples of the fluorine atom-containing polymer include 1,1,1,3,3,3-hexafluoro-2-propyl (meth) acrylate, 1,1-difluoro-1-ethoxycarbonylbutan-2-yl ( Examples thereof include those having a structural unit derived from (meth) acrylate or the like containing a fluorine atom such as (meth) acrylate.

  As content of the said fluorine atom containing polymer, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of [A] polymers, 0.5 mass part-15 mass parts are more preferable, 1 More preferred is 10 parts by mass.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industrial Co., Ltd.) Can be mentioned.
As content of the said surfactant, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

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

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like.
As content of the said alicyclic skeleton containing compound, it is 5 mass parts or less normally with respect to 100 mass parts of [A] polymers.

(Sensitizer)
A sensitizer exhibits the effect | action which increases the production amount of the acid from a [B] acid generator etc., and there exists an effect which improves the "apparent sensitivity" of the said radiation sensitive resin composition.

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.
As content of the said sensitizer, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing radiation-sensitive resin composition>
In the radiation sensitive resin composition, for example, the [A] polymer, the [B] acid generator, the [C] organic solvent, and the [D] acid diffusion controller as necessary are mixed at a predetermined ratio. Can be prepared. The radiation-sensitive resin composition is preferably filtered after mixing with, for example, a filter having a pore size of about 0.05 μm. As solid content concentration of the said radiation sensitive resin composition, 0.1 mass%-50 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 1 mass%-20 mass% are more preferable.

<Resist pattern formation method>
The resist pattern forming method is:
A step of forming a resist film with the radiation-sensitive resin composition (hereinafter, also referred to as “resist film forming step”),
A step of exposing the resist film (hereinafter also referred to as “exposure step”), and a step of developing the exposed resist film (hereinafter also referred to as “development step”).
Have

  According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, it is possible to form a resist pattern excellent in LWR performance and resolution while suppressing the generation of OG. Hereinafter, each step will be described.

[Resist film forming 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 ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the application method include spin coating (spin coating), cast coating, roll coating, and the like. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. As PB temperature, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film to be formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

  In the case of immersion exposure, a protective film may be provided on the formed resist film. As the protective film for immersion, a solvent peeling type protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), a developer peeling type protective film that peels off simultaneously with development in the developing step Any of the membranes (see, for example, WO 2005-069076 and WO 2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

[Exposure process]
In this step, the resist film formed in the resist film forming step is exposed by irradiating with radiation, for example, through a photomask or the like (in some cases through an immersion medium such as water). As the radiation used for exposure, depending on the line width of the target pattern, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (13.5 nm, extreme ultraviolet light), X-rays, γ-rays; Examples thereof include charged particle beams such as α rays. 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 EUV and electron beams are more preferable. According to the resist pattern forming method, by using the radiation sensitive resin composition described above, the influence of OOB can be reduced, and a resist pattern having excellent LWR performance and resolution can be formed. The generation of effects is particularly significant in the case of EUV and electron beams.

  When exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

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

[Development process]
In this step, the resist film exposed in the exposure step is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with water or a rinse solution such as alcohol and then dry.

As a developer used for the above 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, 1,5-diazabicyclo- [4 .3.0] -5 aqueous solution in which at least one alkaline compound such as 5-nonene is dissolved. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.
In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents can be mentioned.
As said organic solvent, 1 type (s) or 2 or more types of the solvent enumerated as [E] solvent of the above-mentioned radiation sensitive resin composition are mentioned, for example. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. Examples of components other than the organic solvent in the developer include water and silicone oil.

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

<Polymer>
The polymer is
At least one selected from the group consisting of the structural unit represented by the above formula (i-1) and the structural unit represented by the above formula (i-2), and the structure represented by the above formula (p-1). And at least one selected from the group consisting of a unit and a structural unit represented by the above formula (p-2).
Since the polymer has the above-described properties, the radiation-sensitive resin composition containing the polymer has excellent LWR performance and resolution, and suppresses the generation of OG from the formed resist film. be able to. Therefore, the polymer can be suitably used as a polymer component of the radiation sensitive resin composition.
The said polymer is mentioned above as the [A] polymer of the said radiation sensitive resin composition.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The physical property values in the examples were measured by the following methods.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using Tosoh GPC columns (G2000HXL: 2, G3000HXL: 1, G4000HXL: 1), flow rate: 1.0 mL / min, elution solvent: THF, sample concentration: 1.0 mass%, sample injection amount: Measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of 100 μL, column temperature: 40 ° C., detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[Content ratio of low molecular weight part]
The content ratio (mass%) of the low molecular weight part (part of molecular weight less than 1,000) of the polymer is HPLC column (Intersil ODS-25 μm, 4.6 mmφ × 250 mm, GL Sciences Inc.), flow rate: 1.0 mL / Min, elution solvent: acrylonitrile / 0.1% by mass phosphoric acid aqueous solution, sample concentration: 1.0% by mass, sample injection amount: 100 μL, detector: by high performance liquid chromatography (HPLC) according to the analytical conditions of the differential refractometer It was measured.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis for determining the content ratio of the structural unit of the polymer was performed using a nuclear magnetic resonance apparatus (JNM-ECX400, JEOL Ltd.) and deuterated chloroform as a measurement solvent.

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (S-1))
To the Schlenk tube purged with nitrogen, 10.0 g (43.1 mmol) of 5-bromoacenaphthene and 50 g of diethyl ether were added and stirred at -35 ° C. 18.1 mL (2.5 M, 45.2 mmol) of diethyl ether solution of n-butyllithium was added dropwise, and the mixture was warmed to room temperature over 2 hours with stirring. After cooling to −78 ° C., 7.51 g (45.2 mmol) of hexafluoroacetone was added using a dry ice condenser, sealed, stirred for 2 hours, slowly warmed to room temperature, and then stirred for 3 hours. did. After excess hexafluoroacetone was distilled off, 36 g of hydrochloric acid in diethyl ether (1M) was added, and the precipitated LiCl was removed by filtration. The obtained filtrate was washed twice with water and dried over anhydrous sodium sulfate, and then the solvent was distilled off. The obtained brown oil was recrystallized from hexane to obtain 11.1 g (yield 80%) of a compound represented by the following formula (Sa) as colorless crystals.
Next, 11.1 g (34.5 mmol) of the compound (Sa) obtained above, 6.4 g (36.2 mmol) of N-bromosuccinimide (NBS), 0.3 g (1.7 mmol) of AIBN and the solvent 30 g of chlorobenzene was put in a flask and heated and stirred at 60 ° C. for 4 hours. After the precipitate was filtered, the obtained filtrate was washed twice with water and dried over anhydrous sodium sulfate, and then the solvent was distilled off. To the obtained crude crystals, 1.8 g (34.5 mmol) of sodium methoxide and THF as a solvent were added and stirred. Thereafter, washing with water was performed twice, and after drying with anhydrous sodium sulfate, the solvent was distilled off. By recrystallizing the obtained brown oil from hexane, 7.9 g (yield 72%) of a compound represented by the following formula (S-1) was obtained as colorless crystals.

[Synthesis Examples 2 and 3] (Synthesis of Compounds (S-2) and (S-3))
By appropriately selecting a bromoacenaphthene compound and a carbonyl compound and performing the same operation as in Synthesis Example 1, compounds represented by the following formulas (S-2) and (S-3) were synthesized.

[Synthesis Example 4] (Synthesis of Compound (S-4))
To a 500 mL three-necked flask purged with nitrogen, 300 mL of THF, 31.8 g (100 mL) of the compound (S-1) synthesized above, and 22.9 g (105 mmol) of di-tert-butyl dicarbonate (Boc ₂ O) were added and stirred. . Thereafter, 1.2 g (10 mmol) of 4- (dimethylamino) pyridine (DMAP) was added. Subsequently, it stirred at normal temperature for 2 hours, and concentrated. The obtained colorless oil was recrystallized from hexane to obtain 25.2 g of a compound represented by the following formula (S-4) as colorless crystals (yield 70%).

[Synthesis Example 5] (Synthesis of Compound (S-5))
To a 200 mL eggplant flask, 17.2 g (100 mmol) of 4-bromoaniline (the following compound (x1)), 21.8 g (100 mmol) of di-tert-butyl dicarbonate (Boc ₂ O) and 100 mL of THF were added and stirred. Three hours later, 100 mL of pure water was added to quench, and extraction was performed with 400 mL of ethyl acetate. The solvent was distilled off from the resulting extract to obtain 24.5 g of the following compound (x2) as a colorless transparent liquid (yield 90%). Next, 30 mL of THF and 2.4 g (99 mmol) of magnesium were placed in a 300 mL three-necked flask under a nitrogen stream, and cooled to 0 ° C. A solution obtained by dissolving 24.5 g (90 mmol) of the obtained compound (x2) in 100 mL of THF was slowly added dropwise to this mixture. After confirming the absence of magnesium after completion of the dropwise addition, 3.3 g (200 mmol) of anhydrous hexafluoroacetone was slowly bubbled while maintaining 0 ° C. Then, it was quenched by adding 1M hydrochloric acid in excess, and extracted with 300 mL of ethyl acetate. The obtained organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled off to obtain 19.4 g (75 mmol) of the following compound (x3) as a pale yellow oil (yield 83%). Next, 19.4 g (75 mmol) of the obtained compound (x3), 8.1 g (82.5 mmol) of maleic anhydride and 200 mL of THF were placed in a 500 mL eggplant flask and reacted by refluxing for 5 hours. Thereafter, 100 mL of 1M hydrochloric acid was added to quench the reaction, and the mixture was extracted with 300 mL of ethyl acetate. The obtained organic layer was dried over anhydrous sodium sulfate, and then the solvent was distilled off. The obtained concentrate was recrystallized with toluene / hexane = 1/10 (volume ratio) to obtain 16.3 g (48 mmol) of the following compound (S-5) as colorless crystals (yield 64%).

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

[Example 1] (Synthesis of polymer (A-1))
8.11 g (50 mol%) of the compound (M-1), 5.93 g (30 mol%) of the compound (M-2), and 5.67 g (20 mol%) of the synthesized compound (S-1). It melt | dissolved in 2-butanone 40g, and added AIBN 0.73g (5 mol% with respect to the sum total of a monomer) as a radical polymerization initiator, and prepared the monomer solution. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 400 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, filtered, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (14.6 g, yield 74). %). Mw of the polymer (A-1) was 7,300, Mw / Mn was 1.53, and the content of the low molecular weight portion was 0.04% by mass. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-2), and (S-1) was 49.7 mol% and 30.1 mol%, respectively. And 20.2 mol%.

[Examples 2, 7-12 and 14-16 and Synthesis Examples 6, 7 and 11-15]
Polymers (A-2), (A-7) to (A-12) are obtained by carrying out the same operations as in Example 1 except that the types and amounts of monomers shown in Table 1 are used. And (A-14) to (A-16) and (a-1), (a-2) and (a-6) to (a-10) were synthesized. The total mass of the monomers used was the same as in Example 1.

[Example 3] (Synthesis of polymer (A-3))
Compound (M-1) 55.0 g (50 mol%), Compound (M-6) 29.4 g (30 mol%), Compound (S-1) 38.4 g (20 mol%), radical polymerization initiator 4 g of AIBN and 1 g of t-dodecyl mercaptan were dissolved in 100 g of propylene glycol monomethyl ether, followed by polymerization for 16 hours while maintaining the reaction temperature at 70 ° C. in a nitrogen atmosphere. After completion of the polymerization reaction, the polymerization reaction solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the obtained polymer, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water and solidified, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a time and the white powdery polymer (A-3) was obtained (85.2g, yield 74%). Mw of the polymer (A-3) was 7,100, Mw / Mn was 1.52, and the content of the low molecular weight portion was 0.04% by mass. As a result of ¹³ C-NMR analysis, the content ratios of structural units derived from (M-1), p-hydroxystyrene and (S-1) were 49.2 mol%, 30.0% and 20 respectively. It was 8 mol%.

[Examples 4 to 6 and 13 and Synthesis Examples 8 to 10 and 16 to 18]
Polymers (A-4) to (A-6) and (A-13) and (a-3) were obtained in the same manner as in Example 3 except that the types and amounts of monomers shown in Table 1 were used. -(A-5) and (a-11)-(a-13) were synthesized. The total mass of the monomers used was the same as in Example 3.

  In Table 1 and Table 2, it shows about the yield (%) of the said synthesize | combined polymer, content (mass%) of a low molecular weight part, Mw, Mw / Mn ratio, and the content rate (mol%) of each structural unit. “-” In Table 2 indicates that the corresponding monomer was not used.

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

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

[[C] Organic solvent]
C-1: Propylene glycol monomethyl ether acetate C-2: Cyclohexanone C-3: Cyclopentanone

[[D] acid diffusion controller]
D-1: Triphenylsulfonium 10-camphorsulfonate (compound represented by the following formula (D-1))
D-2: Triphenylsulfonium salicylate (compound represented by the following formula (D-2))
D-3: Tri-n-pentylamine (compound represented by the following formula (D-3))

[Example 17]
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] 4,280 parts by mass of (C-1) as an organic solvent And (C-2) 1,830 parts by mass, and [D] 3.6 parts by mass of (D-1) as an acid diffusion controller, to prepare a solution having a solid content concentration of 2% by mass. Was filtered through a membrane filter having a pore size of 0.20 μm to prepare a radiation sensitive resin composition (J-1).

[Examples 18 to 34 and Comparative Examples 1 to 15]
Except having used each component of the kind and compounding quantity which are shown in following Table 3, it operated similarly to Example 17 and the radiation sensitive resin compositions (J-2)-(J-18) and (CJ-1). ) To (CJ-15) were prepared.

<Formation of resist pattern>
Using a spin coater (CLEAN TRACK ACT8, Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, the prepared radiation sensitive resin composition was applied, subjected to PB at 90 ° C. for 60 seconds, and then at 23 ° C. After cooling for 30 seconds, a resist film with a thickness of 50 nm was formed. Next, the resist film was irradiated with an electron beam using a simple electron beam drawing apparatus (model “HL800D”, Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After irradiation, PEB was performed at 90 ° C. for 60 seconds. Next, using a 2.38 mass% TMAH aqueous solution as an alkali developer, the film was developed at 23 ° C. for 30 seconds, washed with water, and dried to form a positive line and space (1L1S) having a pattern size of 150 nm. A resist pattern was formed.

<Evaluation>
About the radiation sensitive resin composition, according to the following method, the LWR performance and the resolution lithography performance, and the suppression of outgas from the formed resist film were evaluated. The evaluation results are shown in Table 4. A scanning electron microscope (S-9380, Hitachi High-Technologies Corporation) was used for measuring the resist pattern.

[LWR performance (1)]
The formed resist pattern was observed from above the 150 nm LS pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was determined from the distribution of the measured values, and this was defined as LWR performance (1) (nm). LWR performance (1) indicates that the smaller the value, the better. When the value of the LWR performance (1) is compared with the value of the radiation sensitive resin composition of the criteria shown in Table 4 below, an improvement of 10% or more (the value of the LWR performance (1) is 90% or less) is seen. "A (good)" and less than 10% improvement (LWR performance (1) value exceeds 90% and less than 100%), "B (equivalent)", no improvement is seen When it was or worsened (the value of LWR performance (1) was 100% or more), it was evaluated as “C (defect)”. In Table 4, the evaluation result of the radiation sensitive resin composition of an Example and the value of LWR performance (1) of the radiation sensitive resin composition of a criterion are shown.

[Resolution]
The dimension of the minimum resist pattern to be formed was measured, and this measured value was defined as resolution (1) (nm). The resolution (1) indicates that the smaller the measured value, the better. In Table 4, the value of the resolution (1) of the radiation sensitive resin composition of an Example and a criterion is shown.

[Outgas suppression]
The inhibition of outgas from the resist film formed from the radiation sensitive resin composition was evaluated as follows.
In a clean track (ACT-8, Tokyo Electron Ltd.), a radiation sensitive resin composition was spin-coated on a silicon wafer, and then PB was performed at 90 ° C. for 60 seconds to form a resist film having a thickness of 50 nm. Next, using a KrF projection exposure apparatus (S203B, Nikon Corp.), an exposure amount of 15 mJ / cm on a silicon wafer without a mask pattern under the optical conditions of NA: 0.68, sigma: 0.75, and conventional. ^In FIG. This silicon wafer was subjected to outgas analysis by measuring using a commercially available thermal desorption gas chromatography mass spectrometer (SWA-256, GL Sciences Inc.). The organic substance is desorbed from the surface of the silicon wafer at 25 ° C. for 60 minutes, and the desorbed outgas component is once collected in the collection column, and then the collection column is heated at 200 ° C. to remove the organic substance from the collection column. The gas components collected by re-desorption and thermal desorption cold trap injectors were cooled with liquid nitrogen and contracted in volume, and then rapidly heated to 230 ° C. at once. (JNS-GCMATE) GCMS SYSTEM, JEOL Co.) and measured.

The outgas analysis is performed on the compounds represented by the following (G-1), (G-2), (G-3) and (G-4), and a calibration curve is prepared in advance for each commercially available product. Quantification was performed.
The values in Table 4 are relative values when the outgas amount of each compound in the case of the radiation-sensitive resin composition as a criterion is 100. “-” In Table 4 indicates that the corresponding compound was not detected.

[Out-of-band absorption]
The out-of-band absorptivity of the resist film formed from the radiation-sensitive resin composition was evaluated as follows.
In a clean track ACT-8 manufactured by Tokyo Electron Co., Ltd., the prepared radiation sensitive resin composition was spin-coated on a silicon wafer, and then PB was performed at 90 ° C. for 60 seconds to form a resist film having a thickness of 50 nm. Thereafter, using an ArF projection exposure apparatus S306C manufactured by Nikon Corporation, an exposure amount of 3 mJ / cm ² on the silicon wafer without using a mask pattern under the optical conditions of NA: 0.78, Sigma: 0.85, and 2/3 Annular. The whole surface was exposed. Subsequently, patterning was performed by irradiating an electron beam using a simple electron beam drawing apparatus (Hitachi, Ltd., model HL800D, output: 50 KeV, current density: 5.0 A / cm ² ). After the electron beam irradiation, PEB was performed at 100 ° C. for 60 seconds in the clean track ACT-8. Thereafter, in the clean track ACT-8, a 2.38 mass% tetramethylammonium hydroxide aqueous solution was used and developed by the paddle method at 23 ° C. for 1 minute, followed by washing with pure water and drying to obtain a resist pattern. Formed. Each evaluation shown below was performed about the resist pattern formed in this way. The evaluation results are shown in Table 5. The out-of-band absorptivity is evaluated by comparing the result when the electron beam is irradiated after ArF irradiation shown in Table 5 below and the result when only the electron beam is irradiated without performing the ArF irradiation shown in Table 4 above. can do.

(Sensitivity (μC / cm ² ))
Optimum exposure dose is used to form a line-and-space pattern (1L1S) having a line width of 150 nm and a space portion having a spacing of 150 nm formed by adjacent line portions with a one-to-one line width. This optimum exposure amount was defined as sensitivity (μC / cm ² ).

(LWR performance increase rate)
The formed resist pattern was observed from above the 150 nm LS pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, 3 sigma values were calculated from the distribution of the measured values, and LWR performance (2) was obtained. The value of LWR performance (2) obtained for the same radiation-sensitive resin composition was compared with the value of LWR performance (1), and the ratio increased ((LWR performance (2) / LWR performance (1) -1). ) × 100) (%) was defined as the LWR performance increase rate (%). The LWR performance increase rate indicates that the smaller the value, the better. When the LWR performance increase rate is 10% or more improved (the LWR performance increase rate is 110% or more) when compared to the values for the radiation-sensitive resin composition of the criteria shown in Table 5, In the case of “A (good)” and an improvement of 0% or more and less than 10% (LWR performance increase rate value is more than 0% and less than 110%), “B (equivalent)”, no improvement was seen or When it deteriorated (the value of LWR performance increase rate was 0% or less), it was evaluated as “C (defect)”. In Table 5, the evaluation result of the radiation sensitive resin composition of an Example and the value of the LWR performance increase rate of the radiation sensitive resin composition of evaluation criteria are shown.

(Resolution (2))
The dimension of the minimum resist pattern to be formed was measured, and this measured value was defined as resolution (2) (nm). The resolution (2) indicates that the smaller the measured value, the better. In Table 5, the value of the resolution (2) of the radiation sensitive resin composition of an Example and a criterion is shown.

  As is clear from the results in Tables 4 and 5, all of the radiation-sensitive resin compositions of Examples had good LWR performance, resolution, outgas suppression and out-of-band absorption. In the radiation-sensitive resin composition of the comparative example, the LWR performance, resolution, outgas suppression and out-of-band absorption were all inferior to those of the examples.

  According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist film having excellent out-of-band absorbability while suppressing the generation of OG from the resist film. A resist pattern having a small and high resolution can be formed. Moreover, the polymer of this invention can be used suitably as a component of the said radiation sensitive resin composition. Therefore, they can be suitably used for forming a fine resist pattern in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims (7)

At least one selected from the group consisting of a structural unit represented by the following formula (i-1) and a structural unit represented by the following formula (i-2), and a structure represented by the following formula (p-1) A polymer having at least one selected from the group consisting of a unit and a structural unit represented by the following formula (p-2);
A radiation-sensitive resin composition comprising a radiation-sensitive acid generator and an organic solvent.

(In formula (i-1), each L ¹ independently represents a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or an arylene having 6 to 20 carbon atoms. Or a divalent group in which these groups and at least one selected from the group consisting of —O— and —CO— are combined, and each R ⁷ independently represents a hydrogen atom, a hydroxy group, or a carboxy group; Group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or a monovalent organic group having an —OR ^A group at its terminal ( ^A ) (wherein the —OR ^A group is bonded to a carbon atom having at least one fluorine atom or fluorinated alkyl group) R ^A is a hydrogen atom or a monovalent organic having 1 to 20 carbon atoms; is a group. However, less of R ⁷ Also one is an organic group (a).
In formula (i-2), L ² is a (n + 1) -valent derived from any one of an alkane having 1 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 15 carbon atoms, and an arene having 6 to 20 carbon atoms. It is a group. R ^{7 ′} is a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. Group (a). n is an integer of 1 to 3. ^'If there are a plurality of a plurality of R ^7' R 7 may be the same or different. However, at least one of R ^{7 ′} is an organic group (a).
In formula (p-1), R ⁸ represents a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ⁹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹⁰ and R ¹¹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents a ring structure having 3 to 20 ring members constituted together with carbon atoms to which they are combined with each other.
In formula (p-2), R ¹² represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ¹³ is a monovalent acid-dissociable group having 4 to 20 carbon atoms. ) The radiation sensitive resin composition according to claim 1, wherein the organic group (a) is represented by the following formula (a ′).

(In formula (a ′), R ^{1 to} R ⁶ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 5 carbon atoms substituted with at least one fluorine atom, provided that R ¹ At least one of ˜R ⁶ is a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. indicating the site that binds to ^{L 2} in ^{L 1} or the formula in the above formula (i-1) (i- 2).)   The radiation-sensitive resin composition according to claim 1, wherein the polymer has a structural unit represented by the formula (i-1) and a structural unit represented by the formula (p-1). The radiation-sensitive resin composition according to claim 1, wherein the polymer further comprises at least one selected from the group consisting of structural units represented by the following formulas (ii-1) to (ii-4).

(In formulas (ii-1) to (ii-4), R ^C each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
In formulas (ii-1) to (ii-3), a is independently an integer of 1 to 3. R ^B is each independently an alkyl group having 1 to 5 carbon atoms. b is an integer of 0-4 each independently. If R ^B is plural, or different in each of the plurality of R ^B identical. However, 1 ≦ a + b ≦ 5 is satisfied.
In formula (ii-4), L ³ and L ⁴ each independently represent a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or 6 to 20 carbon atoms. Or a divalent group in which these groups are combined with at least one selected from the group consisting of —O— and —CO—. R ¹⁴ represents a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. (A). c is an integer of 1-5. L ⁴ and when ^{R 14} is plural, respectively, may be different in each of the plurality of ^{L 4} and ^{R 14} are the same. However, at least one of R ¹⁴ is the organic group (a). ) Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
A method for forming a resist pattern, wherein the resist film is formed from the radiation-sensitive resin composition according to claim 1.   The resist pattern forming method according to claim 5, wherein the radiation used in the exposure step is EUV or an electron beam. At least one selected from the group consisting of a structural unit represented by the following formula (i-1) and a structural unit represented by the following formula (i-2), and a structure represented by the following formula (p-1) The polymer which has at least 1 sort (s) chosen from the group which consists of a unit and the structural unit represented by a following formula (p-2).

(In formula (i-1), each L ¹ independently represents a single bond, a methylene group, an alkylene group having 2 to 5 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, or an arylene having 6 to 20 carbon atoms. Or a divalent group in which these groups and at least one selected from the group consisting of —O— and —CO— are combined, and each R ⁷ independently represents a hydrogen atom, a hydroxy group, or a carboxy group; Group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or a monovalent organic group having an —OR ^A group at its terminal ( ^A ) (wherein the —OR ^A group is bonded to a carbon atom having at least one fluorine atom or fluorinated alkyl group) R ^A is a hydrogen atom or a monovalent organic having 1 to 20 carbon atoms; is a group. However, less of R ⁷ Also one is an organic group (a).
In formula (i-2), L ² is a (n + 1) -valent derived from any one of an alkane having 1 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 15 carbon atoms, and an arene having 6 to 20 carbon atoms. It is a group. R ^{7 ′} is a hydrogen atom, a hydroxy group, a carboxy group, a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or the above organic group. Group (a). n is an integer of 1 to 3. ^'If there are a plurality of a plurality of R ^7' R 7 may be the same or different. However, at least one of R ^{7 ′} is an organic group (a).
In formula (p-1), R ⁸ represents a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ⁹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹⁰ and R ¹¹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups. Represents a ring structure having 3 to 20 ring members constituted together with carbon atoms to which they are combined with each other.
In formula (p-2), R ¹² represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group. R ¹³ is a monovalent acid-dissociable group having 1 to 20 carbon atoms. )