JP6606926B2 - Radiation-sensitive resin composition, resist pattern forming method and compound - Google Patents

Description

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

  Radiation sensitive resin compositions used for fine processing by lithography are far ultraviolet rays such as KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), extreme ultraviolet light (EUV: Extreme Ultraviolet, wavelength 13.5 nm). The acid is generated in the exposed part by irradiation with charged particle beams such as electron beams, and the chemical reaction using this acid as a catalyst causes a difference in the dissolution rate in the developer between the exposed part and the unexposed part. A resist pattern is formed thereon.

  At present, miniaturization of the resist pattern processing technique is being attempted by using a laser beam having a shorter wavelength, an electron beam, an immersion exposure apparatus, or the like. Accordingly, the radiation-sensitive resin composition has not only excellent radiation sensitivity but also LWR (Line Width Roughness) performance, CDU (Critical Dimension Uniformity) performance, EL (Exposure Latency) performance, and development. It is required to obtain a high-accuracy pattern with high yield and excellent defect suppression performance. In response to these requirements, the types and molecular structures of acid generators, acid diffusion controllers and other components used in radiation sensitive resin compositions have been studied in detail. An onium salt compound composed of a neutral onium cation and a weak acid anion loses its acid trapping function in the exposed area and exhibits the acid trapping function only in the unexposed area. -125907, JP-A-8-146610 and JP-A-2000-298347).

  However, at present, when the miniaturization of the resist pattern has progressed to a level of 45 nm or less, the required level of the performance is further increased, and the conventional radiation-sensitive resin composition satisfies these requirements. I can't make it happen.

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

  The present invention has been made based on the above circumstances, and its purpose is radiation sensitivity excellent in LWR performance, CDU performance, EL performance, and development defect suppression (hereinafter also referred to as “LWR performance, etc.”). It is in providing a conductive resin composition.

（式（ｉ）中、Ｒ^１及びＲ^２は、それぞれ独立して、水素原子、−ＣＲ^Ａ _２−Ｒ^Ｂ又は−ＣＯＯＲ^Ｂである。Ｒ^Ａは、それぞれ独立して、水素原子、ハロゲン原子又は炭素数１〜２０の炭化水素基である。Ｒ^Ｂは、それぞれ独立して、水素原子又は炭素数１〜２０の１価の有機基である。Ｒ^３は、−ＣＲ^Ｃ _２−である。Ｒ^Ｃは、それぞれ独立して、水素原子、ハロゲン原子又は炭素数１〜２０の炭化水素基である。Ｒ^１及びＲ^２又はＲ^１及びＲ^３は互いに合わせられ、これらが結合する窒素原子と共に環員数３〜２０の環構造を形成してもよい。＊は、上記（チオ）アセタール化合物の式（ｉ）で表される基以外の部分との結合部位を示す。） The invention made to solve the above problems is a polymer having a structural unit containing an acid-dissociable group (hereinafter also referred to as “structural unit (I)”) (hereinafter also referred to as “[A] polymer”). , An acid generator that generates an acid upon exposure (hereinafter also referred to as “[B] acid generator”), and a (thio) acetal compound having a group represented by the following formula (i) (hereinafter referred to as “[C]”). A radiation-sensitive resin composition containing a compound.

(In the formula (i), ^{R 1} and ^{R 2} are each independently a hydrogen ^atom, a _-CR A 2 -R ^B or -COOR ^B .R ^A are each independently a hydrogen atom, a halogen atom or .R ^B is a hydrocarbon group having 1 to 20 carbon atoms are each independently, .R ³ is a monovalent organic group hydrogen atom or a C 1-20, ^-CR _{C 2} - is R ^C each independently represents a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R ¹ and R ² or R ¹ and R ³ are combined with each other, and a nitrogen atom to which these are bonded And may form a ring structure having 3 to 20 ring members, * indicates a bonding site with a moiety other than the group represented by the formula (i) of the (thio) acetal compound.

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

  Yet another invention made to solve the above problems is a (thio) acetal compound represented by any one of formulas (1-1), (1-2) and (1-3) described later.

Here, the “organic group” refers to a group containing at least one carbon atom.
The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

  According to the radiation sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern that exhibits excellent EL performance and is excellent in LWR performance, CDU performance, and development defect suppression. The compound of this invention can be used suitably as a component of the said radiation sensitive resin composition. Therefore, the radiation sensitive resin composition, the resist pattern forming method, and the compound can be suitably used for manufacturing a semiconductor device that is expected to be further miniaturized in the future.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer, a [B] acid generator, and a [C] compound. The radiation-sensitive resin composition contains a [D] solvent and a polymer having a higher fluorine atom content than the [A] polymer (hereinafter, also referred to as “[E] polymer”) as suitable components. Also good. Furthermore, the said radiation sensitive resin composition may contain the other arbitrary component in the range which does not impair the effect of this invention. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having the structural unit (I). According to the radiation-sensitive resin composition, the acid-dissociable group of the [A] polymer in the exposed portion is dissociated by the acid generated from the [B] acid generator and the like by irradiation with radiation, and the exposed portion and the unexposed portion. And a difference in solubility in the developer occurs, and as a result, a resist pattern can be formed. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group and dissociates by the action of an acid. [A] The polymer is usually a base polymer in the radiation-sensitive resin composition. The “base polymer” refers to a polymer that is a main component of the polymers constituting the resist pattern, and preferably occupies 50% by mass or more, more preferably 60% by mass or more.

  [A] The polymer 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 addition to the structural unit (I) (hereinafter also referred to as “structural unit (II)”). ), A structural unit represented by the following formula (3) (hereinafter also referred to as “structural unit (III)”), and a structural unit containing a hydroxy group (hereinafter also referred to as “structural unit (IV)”). Is preferable, and may have other structural units other than these structural units. [A] The polymer may have one or more of these structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group.
Examples of the structural unit (I) include a structural unit represented by the following formula (2-1) (hereinafter also referred to as “structural unit (I-1)”) and a following formula (2-2). And a structural unit (hereinafter also referred to as “structural unit (I-2)”).

In the formula ^{(2-1), R 14} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹⁶ and R ¹⁷ 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 are An alicyclic structure having 3 to 20 ring members is represented together with the carbon atoms to which they are bonded together.
In the formula ^{(2-2), R 20} is a hydrogen atom or a methyl group. L ¹ is a single bond, —CCOO— or —CONH—. R ²¹ , R ²² and R ²³ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms.

R ¹⁴ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹⁵ include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent alicyclic group having 3 to 20 carbon atoms. Examples include hydrocarbon groups and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

Examples of the chain hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, and a pentyl group. An alkyl group;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.

Examples of the alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by R ¹⁶ and R ¹⁷ include those having 1 to 10 carbon atoms among the monovalent chain hydrocarbon groups exemplified for R ¹⁵ above. And the like.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by R ¹⁶ and R ¹⁷ together with the carbon atom to which they are bonded include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, Monocyclic cycloalkane structures such as cyclooctane structures;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

As the structural unit (I-1), structural units represented by the following formulas (2-1-1) to (2-1-5) (hereinafter referred to as “structural units (I-1-1) to (I-1) −5) ”) is preferred.
As the structural unit (I-2), a structural unit represented by the following formula (2-2-1) (hereinafter also referred to as “structural unit (I-2-1)”) is preferable.

In the above formulas (2-1-1) to (2-1-5), R ^{14 to} R ¹⁷ have the same meaning as the above formula (2-1). R ^{15 ′} , R ^{16 ′} and R ^{17 ′} are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. np is each independently an integer of 1 to 4.
In the above formula ^(2-2-1), R 20 ^{to R 23} is as defined in the above formula (2-2).

  Examples of the structural units (I-1-1) to (I-1-5) include structural units represented by the following formulas.

In the above formula, R ¹⁴ has the same meaning as the above formula (2-1).

  Among these, structural units derived from 2-alkyl-2-adamantyl (meth) acrylate, structural units derived from 1-alkyl-1-cyclopentyl (meth) acrylate, 2- (1-adamantyl) -2-propyl Structural unit derived from (meth) acrylate, structural unit derived from 2-alkyl-2-tetracyclododecan-yl (meth) acrylate, structure derived from 2- (1-cyclohexyl) -2-propyl (meth) acrylate A unit, a structural unit derived from t-decane-yl (meth) acrylate, and a structural unit derived from 1-alkyl-1-cyclooctyl (meth) acrylate are preferred.

  Examples of the structural unit (I-2) include structural units represented by the following formulas.

In the above formula, R ²⁰ has the same meaning as the above formula (2-2).

  As the structural unit (I-2), a structural unit derived from p- (1-cyclohexylethoxyethoxy) styrene is preferable.

  As a content rate of structural unit (I), 10 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-80 mol% are more preferable, 30 mol% More preferred is ˜75 mol%. By making the content rate of structural unit (I) into the said range, the sensitivity of the said radiation sensitive resin composition can be raised more, and, as a result, lithography performance can be improved more.

[Structural unit (II)]
The structural unit (II) 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 (except for the structural unit (I)). [A] By further having the structural unit (II), the polymer can appropriately adjust the solubility in the developer, and as a result, the lithography performance of the radiation-sensitive resin composition is further improved. be able to. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved.

  Examples of the structural unit (II) 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 or a trifluoromethyl group.

  As the structural unit (II), a structural unit having a lactone structure is preferable, and norbornanelactone-yl (meth) acrylate, 5-cyano-norbornanelactone-yl (meth) acrylate, oxynorbornanelactone-yl (meth) acrylate, γ -More preferred are structural units each derived from butyrolactone-yl (meth) acrylate.

  As a content rate of the said structural unit (II), 80 mol% or less is preferable with respect to all the structural units in a [A] polymer, 10 mol%-70 mol% are more preferable, 20 mol%-60 mol% are Further preferred. By making the content rate of structural unit (II) into the said range, the LWR performance of the said radiation sensitive resin composition etc. can be improved further. In addition, the adhesion between the obtained resist pattern and the substrate can be further improved.

[Structural unit (III)]
The structural unit (III) is a structural unit represented by the following formula (3). When KrF excimer laser light, EUV, electron beam, or the like is used as the radiation to be irradiated, the radiation sensitive resin composition increases the sensitivity because the polymer [A] has the structural unit (III). Can do.

In the above formula ^{(3), R 18} is a hydrogen atom or a methyl group. R ¹⁹ is a monovalent organic group. p is an integer of 0-3. When p is 2 or 3, a plurality of R ¹⁹ may be the same or different. q is an integer of 1 to 3. However, p + q is 5 or less.

R ¹⁸ is preferably a hydrogen atom from the viewpoint of the copolymerizability of the monomer giving the structural unit (III).

Examples of the monovalent organic group represented by R ¹⁹ include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 carbon atoms. To 20 monovalent aromatic hydrocarbon groups, groups in which some or all of the hydrogen atoms of these groups have been substituted with substituents, carbon-carbon of these groups, -CO-, -CS-, -O-, -S-, or -NR "-or a group containing a group obtained by combining two or more of these. R" is a hydrogen atom or a monovalent organic group.
Among these, a monovalent chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is more preferable.

  As said p, the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.

  The q is preferably 1 or 2, and more preferably 1.

  Examples of the structural unit (III) include structural units represented by the following formulas (3-1) to (3-4).

In the formulas (3-1) to (3-4), R ¹⁸ has the same meaning as the formula (3).

  Among these, the structural unit represented by the above formula (3-1) and the structural unit represented by (3-2) are preferable, and the structural unit represented by the above formula (3-1) is more preferable.

  As a content rate of structural unit (III), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 30 mol%-80 mol% are more preferable, 50 mol% More preferred is ˜75 mol%. By making the content rate of structural unit (III) into the said range, the said radiation sensitive resin composition can improve a sensitivity more.

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

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing a hydroxy group. [A] A polymer can have more moderate solubility by having a structural unit (IV). Moreover, the adhesiveness to the board | substrate of the resist pattern formed from the said resin composition can be improved.

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

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

  Among these, a structural unit having a hydroxyadamantyl group is preferable, and a structural unit derived from 3-hydroxyadamantyl (meth) acrylate is more preferable.

  As a content rate of the structural unit containing the said hydroxyl group, 35 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, 30 mol% or less is preferable, and 3 mol%-25 mol% are preferable. Further preferred. When the said content rate exceeds the said upper limit, the pattern formation property of the said radiation sensitive resin composition may fall.

[Other structural units]
[A] The polymer may have other structural units in addition to the structural units (I) to (IV). Examples of the other structural units include a structural unit containing at least one selected from the group consisting of a ketonic carbonyl group, a cyano group, a carboxy group, a nitro group, and an amino group, and a non-dissociable monovalent alicyclic group. Examples include a structural unit derived from a (meth) acrylic acid ester containing a hydrocarbon group. As a content rate of another structural unit, 20 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 10 mol% or less is more preferable.

  As content of the [A] polymer in the said radiation sensitive resin composition, 70 mass% or more is preferable with respect to the total solid in the said radiation sensitive resin composition, 80 mass% or more is more preferable, 85 mass% or more is more preferable.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing a monomer giving each structural unit in a suitable solvent using a radical polymerization initiator or the like.

Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropyl). Azo radical initiators such as propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate;
Examples thereof include peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide and cumene hydroperoxide.
Among these, AIBN and dimethyl 2,2′-azobisisobutyrate are preferable, and AIBN is more preferable. These radical initiators can be used alone or in combination of two or more.

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

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

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, 2,500 or more and 20,000 or less are more preferable, and 3,000 or more and 15,000 are particularly preferable. [A] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said radiation sensitive resin composition improve. [A] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may deteriorate.

  [A] The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually from 1 to 5, preferably from 1 to 3, more preferably from 1 to 2. .

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 "G2000HXL" from Tosoh Corporation, 1 "G3000HXL", 1 "G4000HXL" Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. Since the acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of these polymers in the developer changes, the radiation-sensitive resin composition Thus, a resist pattern can be formed. The content form of the [B] acid generator in the radiation-sensitive resin composition may be a low molecular compound form (hereinafter referred to as “[B] acid generator” as appropriate), as described later. It may be a form incorporated as a part or both of these forms.

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

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

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

  [B] The acid generator is preferably a compound represented by the following formula (4). [B] By making the acid generator a compound represented by the following formula (4), the diffusion length of acid generated by exposure in the resist film due to the interaction with the polar structure of the [A] polymer, etc. As a result, the LWR performance and the like of the radiation sensitive resin composition can be further improved.

In the above formula (4), R ^a1 is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ^a2 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. M ⁺ is a monovalent radiation-sensitive onium cation.

The “number of ring members” in R ^a1 means the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure, and in the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up a polycycle.

Examples of the monovalent group including an alicyclic structure having 6 or more ring members represented by R ^a1 include monocyclic cycloalkyl groups such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ^a1 include a group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacyclohexyl group, an azacycloheptyl group, a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The number of ring members of the group represented by R ^a1 is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the diffusion length of the acid described above becomes more appropriate.

Among these, R ^a1 is preferably a monovalent group containing an alicyclic structure having 9 or more ring members, or a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, an adamantyl group, a hydroxyadamantyl group Group, norbornanelactone-yl group, and 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group are more preferable, and an adamantyl group is more preferable.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ^a2 include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which is substituted with a fluorine atom.
Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group, and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent radiation-sensitive onium cation represented by M ⁺ is a cation that decomposes upon irradiation with radiation. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiation-sensitive onium cation and sulfonate anions. Examples of the monovalent radiation-sensitive onium cation represented by M ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples include radiation-sensitive onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (X-1), a tetrahydrothiophenium cation represented by the following formula (X-2), and an iodonium cation represented by the following formula (X-3) preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, substituted or unsubstituted. aromatic hydrocarbon group having 6 to 12 carbon atoms, a or a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or two or more are combined with each other configured ring of these groups . R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.
In the above formula (X-2), R ^b1 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon having 6 to 8 carbon atoms. It is a group. k4 is an integer of 0-7. If R ^b1 is plural, the plurality of R ^b1 may be the same or different, and plural R ^b1 may represent a constructed ring aligned with each other. R ^b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0-6. If R ^b2 is plural, the plurality of R ^b2 may be the same or different, and plural R ^b2 may represent a keyed configured ring structure. q is an integer of 0-3.
In the above formula (X-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^{c1, R} c2, ^R when ^R and ^{R S} is plural respective plurality of ^{R c1,} R c2, ^{R R} and ^{R S} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Etc.
Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include i-propyl group, i-butyl group, sec-butyl group, t -A butyl group etc. are mentioned.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group; a benzyl group, Examples include aralkyl groups such as phenethyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^b1 and R ^b2 include a phenyl group, a tolyl group, and a benzyl group.

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

R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an unsubstituted linear or branched alkyl group, a fluorinated alkyl group, and an unsubstituted monovalent aromatic hydrocarbon group. , —OSO ₂ —R ″ and —SO ₂ —R ″ are preferred, fluorinated alkyl groups, unsubstituted monovalent aromatic hydrocarbon groups are more preferred, and fluorinated alkyl groups are more preferred. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As k1, k2, and k3 in the formula (X-1), integers of 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is more preferable.
As k4 in the formula (X-2), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 1 is more preferable. k5 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.
As k6 and k7 in the formula (X-3), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

As said M ^<+> , the cation represented by the said Formula (X-1) is preferable, and a triphenylsulfonium cation is more preferable.

  Examples of the acid generator represented by the above formula (4) include compounds represented by the following formulas (4-1) to (4-17) (hereinafter referred to as “compounds (4-1) to (4-17)”. ) ")) And the like.

In the above formulas (4-1) to (4-17), M ⁺ has the same meaning as in the above formula (4).

  [B] Among these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt or a tetrahydrothiophenium salt, and a compound (4-1), a compound (4-2), or a compound (4-12). ) To (4-17) are more preferable.

  In addition, as the [B] acid generator, a polymer in which the structure of the above formula (4) such as a polymer having a structural unit represented by the following formula (4-18) is incorporated as a part of the polymer is also available. preferable.

In said formula (4-18), R 'is a hydrogen atom or a methyl group. M ⁺ is synonymous with the above formula (4).

  [B] As content of the acid generator, when the [B] acid generator is a [B] acid generator, from the viewpoint of securing the sensitivity of the radiation-sensitive resin composition, [A] 100 mass of the polymer. 0.1 parts by mass or more and 30 parts by mass or less are preferable, 0.5 parts by mass or more and 20 parts by mass or less are more preferable, and 1 part by mass or more and 15 parts by mass or less are more preferable. [B] By making content of an acid generator into the said range, the sensitivity of the said radiation sensitive resin composition improves. The radiation-sensitive resin composition may contain one or more [B] acid generators.

<[C] Compound>
[C] The compound is a (thio) acetal compound having a group represented by the following formula (i). The radiation-sensitive resin composition is excellent in LWR performance, CDU performance, EL performance, and development defect suppression by containing a [C] compound in addition to the [A] polymer and [B] acid generator. . The reason why the radiation-sensitive resin composition has the above-described configuration provides the above-described effect is not necessarily clear, but can be inferred as follows, for example. That is, the [C] compound has a group represented by the above formula (i), and [B] functions as an acid diffusion control agent that appropriately controls the diffusion length of the acid generated from the acid generator or the like. Since the compound [C] also has (thio) acetal, it has an appropriate polarity, and the acid diffusion length can be controlled to be appropriately shorter. As a result, it is considered that the LWR performance and the like of the radiation sensitive resin composition are improved.

In the above formula (i), ^{R 1} and ^{R 2} are each independently a hydrogen ^atom, a _-CR A 2 -R ^B, or -COOR ^B. Each R ^A is independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms. R ^B is each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ³ is —CR ^C ₂ —. Each R ^C is independently a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ¹ and R ² or R ¹ and R ³ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded. * Represents a binding site with a moiety other than the group represented by the formula (i) of the (thio) acetal compound.

Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by the above ^RA and ^RC include, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent alicyclic group having 3 to 20 carbon atoms. Examples include hydrocarbon groups and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

Examples of the chain hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, and a pentyl group. An alkyl group;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.

Examples of the alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

The monovalent organic group having 1 to 20 carbon atoms represented by R ^B, for example, a monovalent chain-like hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon having 3 to 20 carbon atoms A hydrogen group, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a group in which some or all of the hydrogen atoms of these groups are substituted with a substituent, and a heteroatom-containing carbon-carbon group of these groups Examples include groups containing groups, groups in which some or all of the hydrogen atoms of these groups are substituted with substituents, and the like.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. For example, the group similar to the group illustrated by said ^RA and ^RC , etc. are mentioned.

  Examples of the heteroatom-containing group contained between carbon and carbon of these groups include groups containing heteroatoms such as oxygen atom, nitrogen atom and sulfur atom, and the like. -CO-, -CS-, -O- , -S-, -NR'- and the like, or a group obtained by combining one or more of them. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

Examples of the substituent for substituting the hydrogen atom of these groups include:
Halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom;
Alkoxy groups such as methoxy group, ethoxy group, propoxy group, cyclohexyloxy group;
Acyl groups such as formyl group, acetyl group, propionyl group, adamantanecarbonyl group;
An acyloxy group such as an acetoxy group, a propionyloxy group, an adamantanecarbonyloxy group;
Alkoxycarbonyl groups such as methoxycarbonyl group and ethoxycarbonyl group;
Examples thereof include a hydroxy group, a carboxy group, an amino group, a cyano group, a nitro group, a sulfonamide group, and an oxo group (referring to an oxygen atom that substitutes two hydrogen atoms bonded to the same carbon atom).
Among these, a halogen atom, an alkoxy group, and a hydroxy group are preferable.

As the ^-CR _A 2 -R ^B, a methyl group, an ethyl group, i- propyl group are preferred.

As the -COOR ^B , a t-butyloxycarbonyl group and a t-heptyloxycarbonyl group are preferable. When -COOR ^B is such a group, the [C] compound exhibits an acid diffusion control function when -COOR ^B is decomposed by the action of an acid generated from the [B] acid generator or the like. Therefore, the radiation sensitive resin composition containing such a [C] compound is more excellent in storage stability.

R ¹ and R ² are preferably both hydrogen atoms.

As said ^RC , a hydrogen atom is preferable.

Examples of the halogen atom represented by R ^A and R ^C include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the ring structure having 3 to 20 ring members together with the nitrogen atom to which R ¹ and R ² or R ¹ and R ³ are bonded together include an azacycloalkane structure and a morpholine structure. Among these, an azacyclopentane structure, an azacyclohexane structure, and a morpholine structure are preferable.

  [C] The compound represented by any one of the following formulas (1-1), (1-2) and (1-3) is preferable.

In the above formulas (1-1) to (1-3),
R ¹ , R ² and R ³ have the same meaning as in the above formula (i).
R ³¹ , R ³² and R ³³ are each independently a single bond or a divalent organic group having 1 to 20 carbon atoms.
R ⁴¹ , R ⁴² and R ⁴³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.
X ¹ and X ² are each independently an oxygen atom or a sulfur atom.
In formula (1-1),
R ¹ may be combined with any one of R ³¹ and R ⁴¹ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³¹ and R ⁴¹ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other and have 3 to 20 ring members together with the carbon atom to which they are bonded. Represents the ring structure of
A ¹ is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.
a is an integer of 1 to 3.
c is 2 or 3.
When there are a plurality of A ¹ , X ¹ , X ² , R ⁵ and R ⁶ , the plurality of A ¹ may be the same or different, the plurality of X ¹ may be the same or different, and the plurality of X ^{2 May be} the same or different, the plurality of R ⁵ may be the same or different, and the plurality of R ⁶ may be the same or different.
In the above formula (1-2),
R ¹ may be combined with any of R ³² and R ⁴² to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³² and R ⁴² may be combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atom to which these groups are bonded.
R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms.
In the above formula (1-3),
R ¹ may be combined with any one of R ³³ and R ⁴³ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³³ and R ⁴³ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
A ² is a single bond, an oxygen atom, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent oxyhydrocarbon group having 1 to 20 carbon atoms.
R ⁹ and R ¹⁰ are each independently a monovalent organic group having 1 to 20 carbon atoms, or a ring structure having 3 to 20 ring members together with carbon atoms to which these groups are combined with each other. Represents.
b is an integer of 1 to 3.
When b is 2 or more, a plurality of A ² may be the same or different, a plurality of X ¹ may be the same or different, a plurality of X ² may be the same or different, and a plurality of R ⁹ May be the same or different, and a plurality of R ¹⁰ may be the same or different.

Said ^R 41 ^{to R 43,} examples of the monovalent organic group having 1 to 20 carbon atoms in R 5 ^{to R 10,} for example, the same groups as the monovalent organic group having 1 to 20 carbon atoms exemplified as the ^{R B} Etc.

Examples of the divalent organic group having 1 to 20 carbon atoms in R ³¹ , R ³² and R ³³ include, for example, a divalent chain hydrocarbon group having 1 to 20 carbon atoms and a divalent fat having 3 to 20 carbon atoms. Examples thereof include a cyclic hydrocarbon group and a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the divalent chain hydrocarbon group, divalent alicyclic hydrocarbon group, and divalent aromatic hydrocarbon group include the monovalent compounds exemplified as R ^{41 to} R ⁴³ and R ^{5 to} R ¹⁰ . Examples include a group obtained by removing one hydrogen atom from a hydrocarbon group.

The divalent organic group having 1 to 20 carbon atoms in R ³¹ , R ³² and R ³³ is a group containing a hetero atom-containing group between carbon and carbon, and part or all of hydrogen atoms of these groups are substituted. It may have a group substituted with a group. Examples of the heteroatom-containing group and substituent in this case include the same groups as the groups exemplified as the heteroatom-containing group and substituent of R ^{41 to} R ⁴³ and R ^{5 to} R ¹⁰ .

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by A ¹ and A ² include alkanediyl groups such as methanediyl group, ethanediyl group, propanediyl group, butanediyl group;
Alkenediyl groups such as ethenediyl group, propenediyl group, butenediyl group;
A divalent chain hydrocarbon group having 1 to 20 carbon atoms such as an alkynediyl group such as an ethynediyl group, a propynediyl group, or a butynediyl group;
Cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group;
A divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms such as a cycloalkenediyl group such as a cyclopropenediyl group, a cyclobutenediyl group, a cyclopentenediyl group, a cyclohexenediyl group, and a norbornenediyl group;
Arenediyl groups such as benzenediyl group, toluenediyl group, xylenediyl group, naphthalenediyl group, anthracenediyl group;
Examples thereof include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms such as arenediylalkanediyl groups such as benzenediylmethanediyl group, benzenediylethanediyl group and naphthalenediylmethanediyl group.
Examples of the divalent oxy hydrocarbon group having 1 to 20 carbon atoms represented by A ^2, for example,
Alkanediyloxy groups such as methanediyloxy, ethanediyloxy, propanediyloxy, butanediyloxy;
Alkenediyloxy groups such as ethenediyloxy group, propenediyloxy group, butenediyloxy group;
A divalent oxy-chain hydrocarbon group having 1 to 20 carbon atoms such as an alkynediyloxy group such as an ethynediyloxy group, a propynediyloxy group, and a butynediyloxy group;
Cycloalkanediyloxy groups such as cyclopropanediyloxy group, cyclobutanediyloxy group, cyclopentanediyloxy group, cyclohexanediyloxy group, norbornanediyloxy group, adamantanediyloxy group;
Divalent oxyalicyclic hydrocarbons having 3 to 20 carbon atoms such as cycloalkenediyloxy groups such as cyclopropenediyloxy group, cyclobutenediyloxy group, cyclopentenediyloxy group, cyclohexenediyloxy group, norbornenediyloxy group Group;
Arenediyloxy groups such as benzenediyloxy group, toluenediyloxy group, xylenediyloxy group, naphthalenediyloxy group, anthracenediyloxy group;
Examples thereof include divalent oxyaromatic hydrocarbon groups having 6 to 20 carbon atoms such as arenediylalkanediyloxy groups such as benzenediylmethanediyloxy group, benzenediylethanediyloxy group, and naphthalenediylmethanediyloxy group.

A ¹ is preferably a single bond or a divalent chain hydrocarbon group, more preferably a single bond or an alkanediyl group, still more preferably a single bond or a methanediyl group, and particularly preferably a single bond.
A ² is preferably a single bond or an oxygen atom.

As a, 1 or 2 is preferable.
b is preferably 1 or 2.
As c, 2 is preferable.

R ³¹ and R ⁴¹ are combined with each other, and a ring structure of 3 to 20 rings formed with the atomic chain to which they are bonded, R ³² and R ⁴² are combined with each other, and these groups are formed with the carbon atom to which they are bonded. A ring structure having 3 to 20 ring members, a ring structure having 3 to 20 ring members formed together with an atomic chain to which R ³³ and R ⁴³ are bonded to each other, and R ⁵ and R ⁶ , or R ⁹ and Examples of the ring structure having 3 to 20 ring members formed together with the carbon atoms to which R ¹⁰ are bonded to each other and bonded to each other include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, Monocyclic saturated hydrocarbon structures such as cyclodecane structure, methylcyclohexane structure, ethylcyclohexane structure;
Monocyclic unsaturated hydrocarbon structures such as cyclobutene structure, cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure, cyclopentadiene structure, cyclohexadiene structure, cyclooctadiene structure, cyclodecadiene structure;
Bicyclo [2.2.1] heptane structure (norbornane structure), bicyclo [2.2.2] octane structure, tricyclo [5.2.1.0 ^2,6 ] decane structure, tricyclo [3.3.1. 1 ^3,7 ] decane structure (adamantane structure), tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbon structures such as dodecane structures;
Bicyclo [2.2.1] heptene structure, bicyclo [2.2.2] octene structure, tricyclo [5.2.1.0 ^2,6 ] decene structure, tricyclo [3.3.1.1 ^3,7 ] Decene structure, tetracyclo [6.2.1.1 ^3,6 . And a polycyclic unsaturated hydrocarbon structure such as 0 ^2,7 ] dodecene structure.
The ring structure having 3 to 20 ring members constituted by R ³³ and R ⁴³ being combined with each other and the atomic chain to which they are bonded is formed with the atomic chain to which R ³¹ and R ⁴¹ are combined with each other. In addition to the ring structure exemplified as the ring structure having 3 to 20 ring members, monocyclic such as oxacyclobutane structure, oxacyclopentane structure, oxacyclohexane structure, oxacycloheptane structure, oxacyclooctane structure, oxacyclodecane structure, etc. Oxacycloalkane structure;
Monocyclic oxacycloalkene structures such as oxacyclobutene structure, oxacyclopentene structure, oxacyclohexene structure, oxacycloheptene structure, oxacyclooctene structure, oxacyclodecene structure;
Polycyclic oxacycloalkane structures such as oxabicyclo [2.2.1] heptane structure (oxanorbornane structure), oxabicyclo [2.2.2] octane structure;
Examples thereof include polycyclic oxacycloalkene structures such as oxabicyclo [2.2.1] heptene structure and oxabicyclo [2.2.2] octene structure.

  The ring structure is preferably a cyclohexane structure, a norbornane structure, an adamantane structure, or a monocyclic oxacycloalkane structure.

As the ^{X 1} and ^{X 2,} oxygen atom is preferable.

  As the compound represented by (1-1), compounds represented by the following formulas (1-1-1) to (1-1-6) are preferable.

  As the compound represented by the above (1-2), compounds represented by the following formulas (1-2-1) and (1-2-2) are preferable.

  As the compound represented by the above (1-3), compounds represented by the following formulas (1-3-1) to (1-3-21) are preferable.

(Method for synthesizing [C] compound)
[C] The compound is, for example, a compound represented by the above formula (1-3), wherein X ¹ and X ² are oxygen atoms, a is 1, A ² is a single bond, R ³³ is a single bond, and R ⁴³ is In the case of a compound represented by the following formula (1-iii) which is a hydrogen atom, it can be synthesized according to the following reaction scheme.

The (thio) acetal chloride represented by the above formula (1-c) is prepared by reacting the carbonyl compound represented by the above formula (1-a) with the dihydroxy chloride represented by the above formula (1-b). Can be obtained.
The (thio) acetal chloride (1-c) and the nitrogen-containing compound represented by the above formula (1-d) are reacted to obtain the (thio) acetal compound represented by the above formula (1-iii). be able to.

  [C] The compounds represented by the above formulas (1-1) and (1-2), which are other examples of the compound, can be selected by appropriately selecting the carbonyl compound to be used and the dihydroxy compound to be reacted. It can be synthesized in the same manner as described above.

In the above scheme, R ¹ , R ² , R ³ , R ⁹ and R ¹⁰ are as defined in the above formula (1-3).

  [C] The lower limit of the content of the compound is preferably 0.5 parts by mass, more preferably 1.0 part by mass, and still more preferably 2.0 parts by mass with respect to 100 parts by mass of the polymer [A]. 3.0 parts by mass is particularly preferred. [C] The upper limit of the content of the compound is preferably 40 parts by mass, more preferably 30 parts by mass, further preferably 25 parts by mass, and particularly preferably 20 parts by mass with respect to 100 parts by mass of the polymer [A]. . By making the content rate of a [C] compound into the said range, the said radiation sensitive resin composition can further improve LWR performance etc. The radiation-sensitive resin composition may contain one or more [C] compounds.

<[D] solvent>
The radiation-sensitive resin composition usually contains a [D] solvent. [D] The solvent is particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, the [C] compound, and the [E] polymer contained as necessary. Not.

  [D] Examples of the solvent include alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, hydrocarbon solvents, and the like.

Examples of the alcohol solvent include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A C2-C18 polyhydric alcohol solvent such as 1,2-propylene glycol;
Examples include C3-C19 polyhydric alcohol partial ether solvents such as propylene glycol monomethyl ether.

Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether) are exemplified.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

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

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

Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms such as n-pentane and n-hexane;
Examples thereof include aromatic hydrocarbon solvents having 6 to 16 carbon atoms such as toluene and xylene.

  Among these, the solvent [D] is preferably an ester solvent or a ketone solvent, more preferably a polyhydric alcohol partial ether carboxylate solvent or a cyclic ketone solvent, a polyhydric alcohol partial alkyl ether acetate, a cycloalcohol. Canon is more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are particularly preferable. The radiation-sensitive resin composition may contain one or more [D] solvents.

<[E] polymer>
The [E] polymer is a polymer having a higher fluorine atom content than the [A] polymer. When the radiation-sensitive composition contains the [E] polymer, when the resist film is formed, the distribution is near the resist film surface due to the oil-repellent characteristics of the [E] polymer in the film. There is a tendency to be unevenly distributed, and 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 the [E] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the said radiation sensitive resin composition contains an [E] polymer, the resist film suitable for an immersion exposure method can be formed.

[E] The fluorine atom content of the polymer is preferably 1% by mass or more, more preferably 2% by mass to 60% by mass, further preferably 4% by mass to 40% by mass, and 7% by mass to 30% by mass. Particularly preferred. [E] When the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

  [E] The fluorine atom content in the polymer is not particularly limited, and may be bonded to any of the main chain, the side chain, and the terminal, but is a structural unit containing a fluorine atom (hereinafter referred to as “structural unit (V)”). It is preferable to have (also called). [E] In addition to the structural unit (V), the polymer preferably has a structural unit containing an acid-dissociable group from the viewpoint of improving development defect suppression of the radiation-sensitive resin composition. Examples of the structural unit containing an acid dissociable group include the structural unit (I) in the [A] polymer.

  [E] The polymer preferably has an alkali dissociable group. [E] When the polymer has an alkali-dissociable group, the resist film surface can be effectively changed from hydrophobic to hydrophilic during alkali development, and the development defect suppression of the radiation-sensitive resin composition is improved. . An “alkali dissociable group” is a group that replaces a hydrogen atom of a carboxy group, a hydroxy group, etc., and dissociates in an alkaline aqueous solution (eg, 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C.). Group.

  As the structural unit (V), a structural unit represented by the following formula (5a) (hereinafter, also referred to as “structural unit (Va)”) and a structural unit represented by the following formula (5b) (hereinafter, At least one selected from the group consisting of “structural units (Vb)” is preferred. The structural unit (V) may have one or more structural units (Va) and structural units (Vb).

[Structural unit (Va)]
The structural unit (Va) is a structural unit represented by the following formula (5a). [E] A polymer can adjust a fluorine atom content rate by having a structural unit (Va).

In said formula (5a), ^Rd is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH— or —O—CO—NH—. R ^e is a monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms.

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

As the _{G, -CO-O -, -} SO 2 -O-NH -, - CO-NH- or -O-CO-NH- are preferred, -CO-O-are more preferred.

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

The monovalent fluorine-cycloaliphatic hydrocarbon group having 4 to 20 carbon atoms represented by R ^e, for example monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl group, difluorocyclopentyl groups Perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Among these, as R ^e , a fluorinated chain hydrocarbon group is preferable, and 2,2,2-trifluoroethyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group is preferable. The group is more preferable, and the 1,1,1,3,3,3-hexafluoro-2-propyl group is more preferable.

  As a content rate of a structural unit (Va), 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [E] polymer, 3 mol%-70 mol% are more preferable, 5 mol% More preferred is ˜50 mol%. By setting it as such a content rate, the fluorine atom content rate of an [E] polymer can be adjusted more appropriately.

[Structural unit (Vb)]
The structural unit (Vb) is a structural unit represented by the following formula (5b). [E] By having the structural unit (Vb), the polymer can adjust the fluorine atom content and change the water repellency and hydrophilicity before and after alkali development.

In said formula (5b), ^Rf is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ¹¹ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, or an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O— at the terminal of R ¹² side of this hydrocarbon group. Alternatively, it has a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ¹² is a single bond or a divalent organic group having 1 to 20 carbon atoms. W ¹ is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. . * ^Indicates a site binding to ^{R 13.} R ¹³ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. s is an integer of 1 to 3. However, when s is 1, R ¹¹ may be a single bond. When s is 2 or 3, a plurality of R ¹² , W ¹ , A ¹ and R ¹³ may be the same or different. When W ¹ is a single bond, R ¹³ is a group containing a fluorine atom.

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

Examples of the (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹¹ include s hydrogen atoms from the monovalent hydrocarbon group exemplified as R ¹ in the above formula (1). Excluded groups and the like.
As said s, 1 or 2 is preferable and 1 is more preferable.
As R ¹¹ , when s is 1, a single bond or a divalent hydrocarbon group is preferable, a single bond or an alkanediyl group is more preferable, a single bond or an alkanediyl group having 1 to 4 carbon atoms is more preferable, A single bond, a methanediyl group, and a propanediyl group are particularly preferable.

As a C1-C20 bivalent organic group represented by said R < ¹² >, from C1-C20 monovalent organic group illustrated as R < ¹ > -R < ³ > in the said Formula (1), for example, 1 And a group excluding individual hydrogen atoms.
R ¹² is preferably a group having a single bond or a lactone structure, more preferably a group having a single bond or a polycyclic lactone structure, and more preferably a group having a single bond or a norbornane lactone structure.

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

As the ^{A 1,} an oxygen _{atom, -CO-O - *, -} SO 2 -O- * are preferred, -CO-O- * is more preferable.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ¹³ include an alkali dissociable group, an acid dissociable group, and a hydrocarbon group having 1 to 30 carbon atoms. Of these, R ¹³ is preferably an alkali-dissociable group. By using R ¹³ as an alkali dissociable group, the resist film surface can be effectively changed from hydrophobic to hydrophilic during alkali development, and development defect suppression of the radiation-sensitive resin composition is further improved. To do.

When R ¹³ is an alkali-dissociable group, R ¹³ is preferably a group represented by the following formulas (iii) to (v) (hereinafter also referred to as “groups (iii) to (v)”). .

In the above formula (iii), R ^3a and R ^3b are each independently a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other and configured with a carbon atom to which they are bonded. Represents an alicyclic structure having 3 to 20 ring members.

In the above formula (iv), R ^3c and R ^3d are each independently a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other to form a nitrogen atom to which they are bonded. Represents a heterocyclic structure having 3 to 20 ring members.

In said formula (v), R ^<3e> is a C1-C20 monovalent hydrocarbon group or a C1-C20 monovalent fluorinated hydrocarbon group.

Examples of the monovalent organic group having 1 to 20 carbon atoms and the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups similar to those exemplified as R ^{1 to} R ^{3 in} the above formula (1). Can be mentioned.

  As the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms, for example, part or all of the hydrogen atoms included in the group exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms is a fluorine atom. Examples include substituted groups.

  The group represented by the following formulas (iii-1) to (iii-4) as the group (iii), and the group represented by the following formula (iv-1) as the group (iv) (V) is preferably a group represented by the following formulas (v-1) to (v-5).

  Among these, the group represented by the formula (v-3) and the group represented by the formula (v-5) are preferable.

R ¹³ is preferably a hydrogen atom, because the solubility of the [E] polymer in an alkaline developer is improved. In this case, if A ¹ is an oxygen atom and W ¹ is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group, the solubility is further improved.

  As a content rate of the said structural unit (Vb), 10 mol%-90 mol% are preferable with respect to all the structural units which comprise a [E] polymer, 20 mol%-85 mol% are more preferable, 40 mol% % To 80 mol% is more preferable. By setting it as such a content rate, the water repellency before and behind alkali development of the resist film surface formed from the said radiation sensitive resin composition, hydrophilicity, etc. can be adjusted more appropriately.

  As a content rate of the said structural unit (V), 20 mol%-90 mol% are preferable with respect to all the structural units which comprise a [E] polymer, 30 mol%-85 mol% are more preferable, 40 mol% % To 80 mol% is more preferable.

  [E] The content ratio of the structural unit containing an acid dissociable group in the polymer (the structural unit (I) in the [A] polymer) is 10 mol with respect to all the structural units constituting the [E] polymer. % To 60 mol% is preferable, 15 mol% to 50 mol% is more preferable, and 20 mol% to 40 mol% is more preferable. [E] By making the content rate of the structural unit containing an acid dissociable group in a polymer into the said range, the development defect inhibitory property of the said radiation sensitive resin composition can further be improved.

  [E] The lower limit of the content of the polymer is preferably 0.1 parts by mass, more preferably 0.2 parts by mass, and even more preferably 0.5 parts by mass with respect to 100 parts by mass of the polymer [A]. 1 part by mass is particularly preferred. [E] The upper limit of the content of the polymer is preferably 30 parts by mass, more preferably 20 parts by mass, further preferably 15 parts by mass, and particularly preferably 10 parts by mass with respect to 100 parts by mass of the polymer [A]. preferable.

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

  [E] The polystyrene-reduced weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is not particularly limited, but is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, 2,500 or more and 20,000 or less are more preferable, and 3,000 or more and 15,000 are particularly preferable. [E] By making Mw of a polymer into the said range, the applicability | paintability and development defect inhibitory property of the said radiation sensitive resin composition improve. [E] If the Mw of the polymer is less than the lower limit, a resist film having sufficient heat resistance may not be obtained. [E] If the Mw of the polymer exceeds the above upper limit, the developability of the resist film may be lowered.

  [E] The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually from 1 to 5, preferably from 1 to 3, more preferably from 1 to 2. .

<Other optional components>
The said radiation sensitive resin composition may contain other arbitrary components other than said [A]-[E] component. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds, and sensitizers. Each of these other optional components may be used alone or in combination of two or more.

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

<Method for preparing radiation-sensitive resin composition>
For example, the radiation-sensitive resin composition is a mixture of [A] polymer, [B] acid generator, [C] compound, optional component contained as necessary, and [D] solvent 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 0.2 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, 1.5 mass%-10 mass% are especially preferable.

<Resist pattern formation method>
The resist pattern forming method includes a step of forming a resist film (hereinafter also referred to as “resist film forming step”), a step of exposing the resist film (hereinafter also referred to as “exposure step”), and the exposed resist. Process of developing the film (hereinafter also referred to as “developing process”)
The resist film is formed from the radiation-sensitive resin composition.

  According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, while exhibiting excellent MEEF performance, depth of focus, and exposure margin, LWR and CDU are small, resolution is high, It is possible to form a resist pattern that is excellent in rectangular shape in cross section. Hereinafter, each step of the resist pattern forming method 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 coating method include spin coating (spin coating), cast coating, and roll coating. 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.

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

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

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by exposure is dissociated. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed 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 alkaline 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, the 1 type (s) or 2 or more types of the solvent enumerated as the [B] solvent of the above-mentioned 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.

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

[Measurement of weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw / Mn)]
Using Tosoh GPC columns (two "G2000HXL", one "G3000HXL", one "G4000HXL"), flow rate: 1.0 ml / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C. Measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard.

[ ¹ H-NMR analysis and ¹³ C-NMR analysis]
It measured using "JNM-Delta400" of JEOL.

<Synthesis of [C] Compound>
[Example 1] (Synthesis of Compound (C-1))
In a 200 mL eggplant-shaped flask, 15.1 g (100 mmol) of adamantanone, 12.2 g (110 mmol) of 3-chloro-1,2-propanediol, 1.90 g (10.0 mmol) of p-toluenesulfonic acid monohydrate , And 100 mL of toluene were added and heated to reflux for 8 hours under a Dean-Stark apparatus. After cooling to room temperature, it was washed three times with an aqueous sodium hydrogen carbonate solution and dried over anhydrous sodium sulfate. After distilling off the solvent, 18.9 g (yield 78%) of a compound represented by the following formula (c-1) was obtained by purification by column chromatography.
Next, 2.43 g (10.0 mmol) of compound (c-1), 4.26 g (50.0 mmol) of piperidine, and 30 mL of N, N-dimethylformamide were added to a 200 mL eggplant-shaped flask, and the mixture was stirred at 80 ° C. for 12 hours. Stir with heating. After the reaction, ethyl acetate was added and the mixture was washed 3 times with a 1% by mass aqueous oxalic acid solution and then once with an aqueous sodium hydrogen carbonate solution. After drying over anhydrous sodium sulfate, the solvent was distilled off and the residue was purified by column chromatography to obtain 1.63 g (yield 56%) of the following compound (C-1).

[Examples 2 to 29] (Synthesis of compounds (C-2) to (C-29))
A precursor represented by the following formulas (C-2) to (C-29) was synthesized by appropriately selecting a precursor and performing the same operation as in Example 1.

<Synthesis of polymer>
The monomers used in the synthesis of each polymer in each example and comparative example are shown below. The following compound (M-21) gives the [A] polymer in which the structure of the [B] acid generator is incorporated.

<[A] Synthesis of polymer>
[Synthesis Example 1] (Synthesis of polymer (A-1))
Compound (M-1) 7.97 g (35 mol%), compound (M-2) 7.44 g (45 mol%), and compound (M-3) 4.49 g (20 mol%) were converted to 2-butanone 40 g. A monomer solution was prepared by adding 0.80 g of AIBN (5 mol% based on the total monomers) as a radical initiator. 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 solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, 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 powder polymer (A-1) (15.2 g, yield 76). %). Mw of the polymer (A-1) was 7,300, and Mw / Mn was 1.53. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-2) and (M-3) is 34.3 mol%, 45.1 mol%, and It was 20.6 mol%.

[Synthesis Examples 2 to 11, 13, and 14] (Synthesis of Polymers (A-2) to (A-11), (A-13), and (A-14))
Polymers (A-2) to (A-11), (A-) are obtained by performing the same operations as in Synthesis Example 1 except that the types and amounts of monomers shown in Table 1 below are used. 13) and (A-14) were synthesized.

[Synthesis Example 12] (Synthesis of Polymer (A-12))
Compound (M-19) 55.0 g (65 mol%) and compound (M-18) 45.0 g (35 mol%), AIBN 4 g as a radical initiator, and 1 g of t-dodecyl mercaptan were added to 100 g of propylene glycol monomethyl ether. Then, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere, and copolymerization was performed for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a period of time to obtain a white powdery polymer (A-12) (65.7 g, yield 77%). Mw of the polymer (A-12) was 7500, and Mw / Mn was 1.90. As a result of ¹³ C-NMR analysis, the content of each structural unit derived from p-hydroxystyrene and (M-18) was 65.4 mol% and 34.6 mol%, respectively.

<Synthesis of [E] polymer>
[Synthesis Example 15] (Synthesis of Polymer (E-1))
Compound (M-22) 82.2 g (70 mol%) and compound (M-10) 17.8 g (30 mol%) were dissolved in 2-butanone 200 g, and AIBN 0.46 g (total single amount) as a radical initiator The monomer solution was prepared by adding 1 mol% to the body. Next, a 500 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. After replacing the solvent with 400 g of acetonitrile, the operation of adding 100 g of hexane and stirring to recover the acetonitrile layer was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution containing 60.1 g of the polymer (E-1) was obtained (yield 60%). Mw of the polymer (E-1) was 15,000, and Mw / Mn was 1.90. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-22) and (M-10) was 70.3 mol% and 29.7 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
Each component used for preparation of each radiation sensitive resin composition is shown below.

[[B] acid generator]
Compounds represented by the following formulas (B-1) to (B-9)

[[C] Compound]
C-1 to C-29 used in Examples: Compounds synthesized in Examples 1 to 29 (Q-1) to (Q-9) used in Comparative Examples: Formulas (Q-1) to (Q-9) below Compound represented by

[[D] solvent]
D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexane D-3: γ-butyrolactone

<Preparation of ArF exposure radiation-sensitive resin composition>
[Example 30] (Preparation of radiation-sensitive resin composition (J-1))
[A] 100 parts by mass of (A-1) as a polymer, [B] 10 parts by mass of (B-1) as an acid generator, 7 parts by mass of compound (C-1) as a [C] compound, [ E] 3 parts by mass of (E-1) as a polymer, and (D-1) 2,427 parts by mass, (D-2) 1,040 parts by mass and (D-3) 200 as a [D] solvent. The radiation sensitive resin composition (J-1) was prepared by mixing a mass part and filtering with a 0.2 micrometer membrane filter.

[Examples 31 to 58 and Comparative Examples 1 to 29]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 30 except that the components of the types and contents shown in Table 2 and Table 3 were used.

<Formation of resist pattern (1)>
On the surface of a 12-inch silicon wafer, using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron), a composition for forming a lower antireflection film (“ARC66” manufactured by Brewer Science) was applied at 205 ° C. Was heated for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On the lower antireflection film, each of the radiation sensitive resin compositions described in Table 4 and Table 5 below was applied using the spin coater, and PB was performed at 100 ° C. for 50 seconds. Thereafter, it was cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 90 nm. Next, this coating film was subjected to an optical condition of NA = 1.35, Dipole 35X (σ = 0.97 / 0.77) using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” manufactured by ASML). Then, it was exposed through a mask pattern for forming a resist pattern of 38 nm line and space (1L / 1S). After the exposure, PEB was performed at 90 ° C. for 50 seconds. Then, using a 2.38 mass% TMAH aqueous solution, performing paddle development at 23 ° C. for 30 seconds, then rinsing with ultrapure water for 7 seconds, and then spin-drying by shaking off at 2,000 rpm for 15 seconds. A 38 nm line and space (1L / 1S) resist pattern was formed.

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

<Evaluation>
About the formed resist pattern, each radiation sensitive resin composition was evaluated by measuring according to the following method. The evaluation results are shown in Table 4 and Table 5 below. A scanning electron microscope (Hitachi High-Technologies “CG-4100”) was used for measuring the resist pattern.

[Radiation sensitivity]
In the formation of the resist pattern, the exposure dose for forming a 38 nm line and space (1L / 1S) resist pattern was determined as the optimum exposure dose (Eop), and this was defined as the radiation sensitivity (mJ / cm ² ).

[LWR performance]
The resist pattern formed by irradiating the exposure amount of Eop obtained above was observed from above the pattern using the scanning electron microscope. A total of 500 line width variations were measured, and a 3-sigma value was determined from the distribution of the measured values, and this was defined as LWR performance (nm). The smaller the value of the LWR performance, the smaller the line play and the better. The LWR performance can be evaluated as “good” when it is 2.5 nm or less, and “bad” when it exceeds 2.5 nm.

[CDU performance]
The resist pattern formed by irradiating the exposure amount of Eop obtained above was observed from above the pattern using the scanning electron microscope. The line width is measured at 20 points in the range of 400 nm, the average value is obtained, the average value is measured at a total of 500 points, and the 3 sigma value is obtained from the distribution of the measured values. ). The smaller the value of the CDU performance, the better the line width variation over a long period. The CDU performance can be evaluated as “good” when it is 1.5 nm or less, and “bad” when it exceeds 2.0 nm.

[EL performance]
The EL performance of each radiation-sensitive resin composition was evaluated by each value of 10% EL, Bridge limit and Collapse limit measured by the following method.

(10% EL)
When the mask pattern for forming a 38 nm line and space (1L / 1S) resist pattern is used, the resist pattern dimension resolved is within ± 10% of the mask design dimension. The ratio to the above Eop was 10% EL (%). The larger the value of 10% EL, the smaller the change amount of the patterning performance with respect to the exposure amount change, and the better. 10% EL can be evaluated as “good” when 18% or more and “bad” when less than 18%.

(Bridge limit)
In the formation of the resist pattern, when the exposure amount is decreased in the case of alkali development from the Eop, and when the exposure amount is increased in the case of organic solvent development, the minimum pattern width that causes a bridge ( (Bridge limit) (nm) was determined, and this value was used as an index of the Bridge limit. As the value of the Bridge limit is larger, the bridge defect is less likely to occur. The Bridge limit can be evaluated as “good” when it is 50 nm or more, and “bad” when it is less than 50 nm.

(Collapse limit)
In the formation of the resist pattern, the minimum pattern width that causes pattern collapse when the exposure amount is increased in the case of alkali development from the Eop and the exposure amount is decreased in the case of organic solvent development ( Collapse limit) (nm) was determined, and this value was used as an index of Collapse limit. The smaller the Collapse limit value, the less likely the resist pattern collapses. The Collapse limit can be evaluated as “good” when it is 28 nm or less, and “bad” when it exceeds 28 nm.

[Development defect suppression]
A coating film is formed with a radiation-sensitive resin composition on a 12-inch silicon wafer on which a lower antireflection film is formed with a composition for forming an lower antireflection film (“ARC66” of Nissan Chemical Co., Ltd.), and is heated at 120 ° C. for 50 seconds. SB was performed to form a resist film having a thickness of 110 nm. Next, an ArF excimer laser immersion exposure apparatus (“NSR-S610C” from NIKON) was used for this resist film, and the target size was 38 nm in width under the conditions of NA = 1.3, ratio = 0.800, Dipole. It exposed through the mask pattern for line and space (1L / 1S) formation. After exposure, PEB was performed at 95 ° C. for 50 seconds. Thereafter, development was performed for 10 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide or butyl acetate using a GP nozzle of a developing device (“Clean Track ACT8” manufactured by Tokyo Electron). In the case of development with an aqueous tetramethylammonium hydroxide solution, rinsing was continued with pure water for 15 seconds, and the solution was shaken off and dried at 2,000 rpm. At this time, the exposure amount for forming 1 L / 1S having a width of 38 nm was determined as the optimum exposure amount. With this optimum exposure amount, 1 L / 1S having a line width of 38 nm was formed on the entire surface of the wafer to obtain a defect inspection wafer. A scanning electron microscope (Hitachi High-Technologies “CC-4000”) was used for length measurement. The number of defects on the defect inspection wafer was measured using a defect inspection apparatus (“KLA2810” manufactured by KLA-Tencor). Then, the measured defects were classified into those judged to be derived from the resist film and foreign matters derived from the outside, and the number of those judged to be derived from the resist film was calculated. The smaller the number of defects judged to be derived from this resist film, the better the defect suppression. Defect suppression can be evaluated as “good” when the number of defects judged to be derived from the resist film is 0.1 piece / cm ² or less, and “bad” when it exceeds 0.1 piece / cm ^2. .

<Preparation of radiation sensitive resin composition for electron beam exposure>
[Example 59] (Preparation of radiation-sensitive resin composition (J-30))
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, 3.6 parts by mass of (C-1) as a [C] compound, In addition, (D-1) 4,280 parts by mass and (D-2) 1,830 parts by mass as a solvent [D] are mixed and filtered through a 0.2 μm membrane filter to obtain a radiation-sensitive resin composition. (J-30) was prepared.

[Examples 60 to 63 and Comparative Examples 30 to 34]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 59 except that the components having the types and contents shown in Table 6 below were used.

<Formation of resist pattern (3)>
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each radiation sensitive resin composition described in Table 7 below was applied, and PB was performed at 90 ° C. for 60 seconds. It was. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with a film thickness of 50 nm. Next, the resist film was irradiated with 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 irradiation, PEB was performed at 120 ° C. for 60 seconds. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern.

<Formation of resist pattern (4)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (3) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed. Formed.

<Evaluation>
Formation of the resist pattern The resist patterns formed in (3) and (4) were evaluated in the same manner as in the above examples. The results are shown in Table 7 below.

  From the results of Table 4, Table 5, and Table 7, the radiation sensitive resin compositions of the examples are LWR performance and CDU performance in the case of ArF exposure and electron beam exposure, in the case of alkali development and in the case of organic solvent development. , It was shown that the EL performance and development defect suppression were excellent. On the other hand, it was also shown that the radiation sensitive resin compositions of the comparative examples were inferior in performance to the examples. In general, it is known that the electron beam exposure shows the same tendency as in the case of EUV exposure. Therefore, even in the case of EUV exposure, according to the radiation-sensitive resin composition of the examples. It is estimated that the LWR performance is excellent.

  According to the radiation sensitive resin composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern that exhibits excellent EL performance and is excellent in LWR performance, CDU performance, and development defect suppression. The compound of this invention can be used suitably as a component of the said radiation sensitive resin composition. Therefore, the radiation sensitive resin composition, the resist pattern forming method, and the compound can be suitably used for manufacturing a semiconductor device that is expected to be further miniaturized in the future.

Claims (5)

A polymer having a structural unit containing an acid dissociable group,
An acid generator that generates an acid upon exposure, and a (thio) acetal compound represented by any one of the following formulas (1-1), (1-2), and (1-3) (provided that the following formula (I- 1) Excluding compounds represented by
A radiation-sensitive resin composition.

(In the formulas (1-1) to (1-3),
R ¹ and ^{R 2} are each independently a hydrogen ^atom, a _-CR A 2 -R ^B, or -COOR ^B. Each R ^A is independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms. R ^B is each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ³ is —CR ^C ₂ —. Each R ^C is independently a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ¹ and R ² or R ¹ and R ³ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded.
R ³¹ , R ³² and R ³³ are each independently a single bond or a divalent organic group having 1 to 20 carbon atoms.
R ⁴¹ , R ⁴² and R ⁴³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.
X ¹ and X ² are each independently an oxygen atom or a sulfur atom.
In formula (1-1),
R ¹ may be combined with any one of R ³¹ and R ⁴¹ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³¹ and R ⁴¹ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other and have 3 to 20 ring members together with the carbon atom to which they are bonded. Represents the ring structure of At least one of the plurality of R ⁵ and the plurality of R ⁶ is a monovalent organic group having 1 to 20 carbon atoms.
A ¹ is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.
a is an integer of 1 to 3.
c is 2 or 3.
When there are a plurality of A ¹ , X ¹ , X ² , R ⁵ and R ⁶ , the plurality of A ¹ may be the same or different, the plurality of X ¹ may be the same or different, and the plurality of X ^{2 May be} the same or different, the plurality of R ⁵ may be the same or different, and the plurality of R ⁶ may be the same or different.
In formula (1-2),
R ¹ may be combined with any of R ³² and R ⁴² to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³² and R ⁴² may be combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atom to which these groups are bonded.
R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms.
In formula (1-3),
R ¹ may be combined with any one of R ³³ and R ⁴³ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³³ and R ⁴³ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
A ² is a single bond, an oxygen atom, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent oxyhydrocarbon group having 1 to 20 carbon atoms.
R ⁹ and R ¹⁰ are each independently a monovalent organic group having 1 to 20 carbon atoms, or a ring structure having 3 to 20 ring members together with carbon atoms to which these groups are combined with each other. Represents. At least one of the one or more R ⁹ and the one or more R ¹⁰ is a monovalent organic group having 1 to 20 carbon atoms.
b is an integer of 1 to 3.
When b is 2 or more, a plurality of A ² may be the same or different, a plurality of X ¹ may be the same or different, a plurality of X ² may be the same or different, and a plurality of R ⁹ May be the same or different, and a plurality of R ¹⁰ may be the same or different.
However, when R ³ is —CH ₂ — and b is 1, R ³³ is a single bond, —CH ₂ — or * —CH ₂ —R ^D —, or R ¹ and R ^33. Are combined with each other to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. ^RD is a monovalent organic group having 1 to 19 carbon atoms. * Indicates a binding site to R ³ . When b is 2, R ³³ and R ⁴³ are combined with each other to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. )

The radiation sensitive resin composition according to claim 1, wherein the structural unit containing the acid dissociable group is represented by the following formula (2-1).

(In the formula (2-1), R ¹⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹⁶ And R ¹⁷ 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 are combined with each other. And represents an alicyclic structure having 3 to 20 carbon atoms together with the carbon atom to which they are bonded.) The radiation sensitive resin composition of Claim 1 or Claim 2 in which the said polymer further has a structural unit represented by following formula (3).

(In Formula (3), R ¹⁸ is a hydrogen atom or a methyl group. R ¹⁹ is a monovalent organic group. P is an integer of 0 to 3. When p is 2 or 3, A plurality of R ¹⁹ may be the same or different, q is an integer of 1 to 3, provided that p + q is 5 or less.) Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
A resist pattern forming method for forming the resist film by using the radiation sensitive resin composition according to claim 1 , 2 or 3 . (Thio) acetal compound represented by any of the following formulas (1-1), (1-2) and (1-3) (however, represented by the following formulas (I-1) to (I-4)) Excluding compounds).

(In the formulas (1-1) to (1-3),
R ¹ and ^{R 2} are each independently a hydrogen ^atom, a _-CR A 2 -R ^B, or -COOR ^B. Each R ^A is independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms. R ^B is each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ³ is —CR ^C ₂ —. Each R ^C is independently a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ¹ and R ² or R ¹ and R ³ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded.
R ³¹ , R ³² and R ³³ are each independently a single bond or a divalent organic group having 1 to 20 carbon atoms.
R ⁴¹ , R ⁴² and R ⁴³ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.
X ¹ and X ² are each independently an oxygen atom or a sulfur atom.
In formula (1-1),
R ¹ may be combined with any one of R ³¹ and R ⁴¹ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³¹ and R ⁴¹ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, or these groups are combined with each other and have 3 to 20 ring members together with the carbon atom to which they are bonded. Represents the ring structure of At least one of the plurality of R ⁵ and the plurality of R ⁶ is a monovalent organic group having 1 to 20 carbon atoms.
A ¹ is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.
a is an integer of 1 to 3.
c is 2 or 3.
When there are a plurality of A ¹ , X ¹ , X ² , R ⁵ and R ⁶ , the plurality of A ¹ may be the same or different, the plurality of X ¹ may be the same or different, and the plurality of X ^{2 May be} the same or different, the plurality of R ⁵ may be the same or different, and the plurality of R ⁶ may be the same or different.
In formula (1-2),
R ¹ may be combined with any of R ³² and R ⁴² to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³² and R ⁴² may be combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atom to which these groups are bonded.
R ⁷ and R ⁸ are each independently a monovalent organic group having 1 to 20 carbon atoms.
In formula (1-3),
R ¹ may be combined with any one of R ³³ and R ⁴³ and may form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. R ³³ and R ⁴³ may be combined with each other to form a ring structure having 3 to 20 ring members together with an atomic chain to which they are bonded.
A ² is a single bond, an oxygen atom, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent oxyhydrocarbon group having 1 to 20 carbon atoms.
R ⁹ and R ¹⁰ are each independently a monovalent organic group having 1 to 20 carbon atoms, or a ring structure having 3 to 20 ring members together with carbon atoms to which these groups are combined with each other. Represents. At least one of the one or more R ⁹ and the one or more R ¹⁰ is a monovalent organic group having 1 to 20 carbon atoms.
b is an integer of 1 to 3.
When b is 2 or more, a plurality of A ² may be the same or different, a plurality of X ¹ may be the same or different, a plurality of X ² may be the same or different, and a plurality of R ⁹ May be the same or different, and a plurality of R ¹⁰ may be the same or different.
However, when R ³ is —CH ₂ — and b is 1, R ³³ is a single bond, —CH ₂ — or * —CH ₂ —R ^D —, or R ¹ and R ^33. Are combined with each other to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. ^RD is a monovalent organic group having 1 to 19 carbon atoms. * Indicates a binding site to R ³ . When b is 2, R ³³ and R ⁴³ are combined with each other to form a ring structure having 3 to 20 ring members together with the atom or atomic chain to which they are bonded. )