WO2014141979A1 - Radiation-sensitive resin composition, resist pattern forming method, radiation-sensitive acid generator and compound - Google Patents

Abstract

The present invention is a radiation-sensitive resin composition which contains a radiation-sensitive acid generator and a polymer having a structural unit that contains an acid-cleavable group, and wherein the radiation-sensitive acid generator contains a compound represented by formula (1). In formula (1), each of R¹ and R² independently represents a monovalent organic group having 1-20 carbon atoms; each of R³, R⁴ and R⁵ independently represents a hydrogen atom or a monovalent organic group having 1-20 carbon atoms; the organic groups may combine together to form a ring structure having 1-20 carbon atoms together with a carbon atom to which the organic groups are bonded; n represents an integer of 1-4; and M⁺ represents a monovalent radiation-decomposable onium cation.

Description

Radiation sensitive resin composition, resist pattern forming method, radiation sensitive acid generator and compound

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

The radiation-sensitive resin composition used for microfabrication by lithography generates acid in the exposed area by irradiation with far ultraviolet rays such as ArF excimer laser light and KrF excimer laser light, and charged particle beams such as electron beams. Due to the chemical reaction using as a catalyst, a difference is caused in the dissolution rate in the developing solution between the exposed portion and the unexposed portion to form a resist pattern on the substrate.

Such a radiation-sensitive resin composition is required to further improve the resolution as the fine processing technology advances. In response to such demands, acid generators used in compositions having various structures have been studied (Japanese Patent Laid-Open Nos. 2002-131897, 2003-140331, and 2009-80474). No. publication).

Recently, however, the radiation-sensitive resin composition is not only excellent in resolution, but also has LWR (Line Width Roughness) performance indicating pattern line width uniformity and MEEF (mask width fidelity of pattern line width). It is also required to have excellent performance (Mask Error Enhancement Factor), and it is also required that a highly accurate resist pattern can be formed while ensuring process stability. However, the above conventional radiation-sensitive resin composition cannot satisfy these requirements. Further, when the above-described conventional acid generator is used, the resist pattern to be formed tends to have a top loss or the like. Therefore, it is required to improve the rectangularity of the cross-sectional shape.

Japanese Patent Laid-Open No. 2002-131897 JP 2003-140331 A JP 2009-80474 A

The present invention has been made based on the above circumstances, and an object thereof is to provide a radiation-sensitive resin composition having excellent LWR performance, MEEF performance, and rectangular cross-sectional shape.

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 “[A] polymer”), and a radiation-sensitive acid generator (hereinafter also referred to as “[B] acid generator”);
Containing
The radiation sensitive acid generator is a radiation sensitive resin composition containing a compound represented by the following formula (1) (hereinafter also referred to as “compound (I)”).

(In formula (1), R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom. Or a monovalent organic group having 1 to 20 carbon atoms, wherein R ¹ to R ⁵ are each a ring having 1 to 20 carbon atoms, which is composed of two or more of these together with the carbon atom to which they are bonded. (It may represent a part of the structure. N is an integer of 1 to 4. M ⁺ is a monovalent radiolytic onium cation.)

The resist pattern forming method of the present invention comprises:
Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
The resist film is formed from the radiation sensitive resin composition.

The radiation sensitive acid generator of the present invention contains compound (I).
The compound of the present invention is compound (I).

Here, “organic group” means a group containing at least one carbon atom.

According to the radiation-sensitive resin composition and resist pattern of the present invention, it is possible to form a resist pattern having a small LWR and excellent cross-sectional rectangularity while exhibiting excellent MEEF performance. The radiation sensitive acid generator of this invention can be used suitably as a component of a radiation sensitive resin composition. The compound of the present invention can be suitably used as the radiation sensitive acid generator. Therefore, they can be suitably used in lithography processes such as semiconductor manufacturing processes that are expected to become increasingly finer in the future.

<Radiation sensitive resin composition>
The radiation sensitive resin composition contains a [A] polymer and a [B] acid generator. The radiation-sensitive resin composition contains [C] acid diffusion controller, [D] fluorine atom-containing polymer (hereinafter also referred to as “[D] polymer”) and [E] solvent as suitable components. In the range which does not impair the effect of this invention, the other arbitrary component may be contained. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (I)”). The “acid-dissociable group” refers to a group that replaces a hydrogen atom of a carboxy group, a phenolic hydroxyl group, or the like and dissociates by the action of an acid. The said radiation sensitive resin composition is excellent in pattern formation property because [A] polymer has structural unit (I).

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

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid dissociable group. For example, a structural unit derived from an acid dissociable group ester of an unsaturated carboxylic acid, a structure derived from an acid dissociable group ester of hydroxystyrene Examples of the unit include a structural unit represented by the following formula (2) (hereinafter also referred to as “structural unit (I-1)”) from the viewpoint of improving the pattern-forming property of the radiation-sensitive resin composition. Is preferred.

 

In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ⁸ and R ⁹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups Represents an alicyclic structure having 3 to 20 carbon atoms which is constituted together with carbon atoms to which they are bonded to each other.

R ⁶ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (I).

Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by R ⁷ to R ⁹ include, for example,
Alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ⁷ to R ⁹ 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 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, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by the chain hydrocarbon group represented by R ⁷ to R ⁹ and the alicyclic hydrocarbon group combined with each other and the carbon atom to which they are bonded include, for example, cyclo Monocyclic cycloalkane structures such as propane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure;
Monocyclic cycloalkene structures such as a cyclopentene structure and a cyclohexene structure;
Polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure and tetracyclododecane structure;
Examples thereof include polycyclic cycloalkene structures such as a norbornene structure and a tricyclodecene structure.
Among these, a monocyclic cycloalkane structure and a polycyclic cycloalkane structure are preferable, and a cyclopentane structure and an adamantane structure are more preferable.

Among these, from the viewpoint of easy dissociation of the acid dissociable group, R ⁷ is an alkyl group having 1 to 4 carbon atoms, and R ⁸ and R ⁹ are combined with each other to form a polycyclic ring or a carbon atom to which they are bonded. It preferably represents a monocyclic cycloalkane structure, wherein R ⁷ is a methyl group, an ethyl group, an i-propyl group, and R ⁸ and R ⁹ are combined with each other, together with the carbon atom to which they are bonded, an adamantane structure, a cyclopentane structure It is more preferable to represent.

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

In the above formulas (2-1) to (2-4), R ⁶ to R ⁹ are as defined in the above formula (2). i and j are each independently an integer of 1 to 4.

I and j are preferably 1.

Examples of the structural unit (I-1) include a structural unit represented by the following formula.

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

Of these, the structural unit (I) is preferably the structural unit (I-1-1) or the structural unit (I-1-2). The structural unit having a cyclopentane structure or the structural unit having an adamantane structure is preferable. More preferred are structural units derived from 1-alkylcyclopentyl (meth) acrylate, more preferred are structural units derived from 2-alkyladamantyl (meth) acrylate, structural units derived from 1-methylcyclopentyl (meth) acrylate, A structural unit derived from ethylcyclopentyl (meth) acrylate, a structural unit derived from 2-methyladamantyl (meth) acrylate, and a structural unit derived from 2-i-propyladamantyl (meth) acrylate are particularly preferred.

The content ratio of the structural unit (I) is preferably 5 mol% to 95 mol%, more preferably 20 mol% to 90 mol%, more preferably 30 mol% with respect to all the structural units constituting the [A] polymer. -80 mol% is more preferable, and 35 mol% -75 mol% is particularly preferable. By making the content rate of structural unit (I) into the said range, the pattern formation property of the said radiation sensitive resin composition 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. [A] Since the polymer further has the structural unit (II), the solubility in the developer can be adjusted. As a result, the radiation-sensitive resin composition has a lithography performance such as resolution. Can be improved. Moreover, the adhesiveness of the resist pattern formed from [A] polymer 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.

Among these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and more preferably a structural unit derived from norbornane lactone-yl (meth) acrylate.

The content ratio of the structural unit (II) is preferably 10% by mole to 80% by mole, more preferably 20% by mole to 70% by mole, and more preferably 25% by mole with respect to all the structural units constituting the [A] polymer. More preferred is ˜60 mol%. By making the content rate of structural unit (II) into the said range, the said radiation sensitive resin composition can improve more adhesiveness with the board | substrate of the resist pattern formed, and lithography performance, such as resolution. .

[Other structural units]
[A] The polymer may have other structural units in addition to the structural units (I) and (II). Examples of the other structural unit include a structural unit containing a polar group (except for those corresponding to the structural unit (II)). [A] The polymer further has a structural unit containing a polar group, whereby the solubility in a developer can be adjusted. As a result, the lithography performance such as the resolution of the radiation-sensitive resin composition can be adjusted. Can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.
Examples of the structural unit having a polar group include a structural unit represented by the following formula.

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

The content of the structural unit having a polar group is preferably 0 mol% to 40 mol%, more preferably 0 mol% to 30 mol%, based on all the structural units constituting the [A] polymer. More preferred is mol% to 20 mol%. By making the content rate of the structural unit which has a polar group into the said range, lithography performance, such as the resolution of the said radiation sensitive resin composition, can further be improved.

[A] The polymer may have a structural unit other than the structural unit having the polar group as another structural unit. As a content rate of such a structural unit, 30 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 20 mol% or less is more preferable.

<[A] 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-cyclopropylpropylene). Pionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), azo radical initiators such as dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroperoxide, And peroxide radical initiators such as cumene hydroperoxide. Of 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 thereof 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.

The reaction temperature in the above polymerization is usually preferably 40 ° C to 150 ° C and 50 ° C to 120 ° C. 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 15,000 or less are more preferable, and 3,000 or more and 10,000 or less are particularly preferable. [A] If the Mw of the polymer is less than the lower limit, the heat resistance of the resulting resist film may be lowered. [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, 1 G3000HXL, 1 G4000HXL (above, Tosoh Corporation)
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more based on the total solid content of the radiation-sensitive resin composition.

<[B] Acid generator>
[B] The acid generator is a radiation-sensitive acid generator containing compound (I). By including the [B] acid generator, the radiation-sensitive resin composition is excellent in LWR performance, MEEF performance, and rectangular shape in cross section. The reason why the radiation-sensitive resin composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, in the sulfonate salt of Compound (I), the R ¹ group is bonded to the carbon atom adjacent to the CF ₂ chain bonded to the sulfonate group, and the R ² group is bonded to the carbon atom adjacent to the carbon atom. Yes. Thus, since it has a sterically crowded structure in the vicinity of the sulfonate group, the diffusion of the acid generated from the compound (I) is moderately suppressed. As a result, the radiation sensitive resin composition containing compound (I) as an acid generator has improved LWR performance and MEEF performance. In addition, since the compound (I) has the above specific structure and has a structure in which the vicinity of the CF ₂ group is sterically crowded, it is unevenly distributed in the surface layer in the resist film by having a fluorine atom. As a result, the rectangularity of the cross-sectional shape of the resist pattern formed from the radiation-sensitive resin composition is improved.

[Compound (I)]
Compound (I) is represented by the following formula (1).

 

In the above formula (1), R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ¹ to R ⁵ may represent a part of a ring structure having 1 to 20 carbon atoms constituted by two or more of them combined with each other and the carbon atom to which they are bonded. n is an integer of 1 to 4. M ⁺ is a monovalent radiolytic onium cation.

Examples of the organic group having 1 to 20 carbon atoms represented by R ¹ to R ⁵ include, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a hetero atom between carbon-carbon of the hydrocarbon group. A hetero atom-containing group having a group, a group in which part or all of the hydrogen atoms of the hetero atom-containing group are substituted with a substituent, and the like.

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

Examples of the chain hydrocarbon group include:
Alkyl groups such as methyl group, ethyl group, propyl group, butyl group,
Alkenyl groups such as ethenyl group, propenyl group, butenyl group,
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

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

Examples of the aromatic hydrocarbon group include:
Aryl groups such as phenyl, tolyl, xylyl, naphthyl and anthryl;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, and naphthylmethyl group.

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

Examples of the substituent include a hydroxy group, a carboxy group, an oxyhydrocarbon group, a carbonyloxyhydrocarbon group, an acyl group, an acyloxy group, a cyano group, a nitro group, and a keto group (= O).

Among these, R ¹ is a viewpoint in which the LWR performance, the MEEF performance, and the rectangular shape of the cross-sectional shape of the radiation-sensitive resin composition are further improved due to the steric crowding of the vicinity of SO ₃ ⁻ among these. From the viewpoint of enhancing the solubility of the compound (I) in an organic solvent, a hydrocarbon group, a carbonyloxy hydrocarbon group, an oxyhydrocarbon group, and an aliphatic heterocyclic group are preferable. From the viewpoint of ease of synthesis of (I), a carbonyloxy hydrocarbon group is more preferred.

The hydrocarbon group is preferably an alicyclic hydrocarbon group or an aromatic hydrocarbon group, more preferably an alicyclic hydrocarbon group, still more preferably a cycloalkyl group, particularly preferably a polycyclic cycloalkyl group, and adamantyl. And the adamantylmethyl group is more particularly preferred.

As the carbonyloxy hydrocarbon group, a carbonyloxy alicyclic hydrocarbon group is preferable, a cycloalkyloxycarbonyl group is more preferable, a polycyclic cycloalkyloxycarbonyl group is more preferable, and a 2-adamantyloxycarbonyl group is particularly preferable. .

When the hydrocarbon group in the carbonyloxy hydrocarbon group of R ¹ is an acid dissociable group, the LWR performance, MEEF performance, and rectangularity of the cross-sectional shape of the radiation-sensitive resin composition can be further improved. This is considered to be because, for example, a carboxy group is generated in the compound (I) in the exposed area, and as a result, the contrast between the exposed area and the unexposed area is improved. Examples of the acid dissociable group include the same groups as those exemplified as the acid dissociable group in the above-mentioned [A] polymer. Among these, a hydrocarbon group having a tertiary carbon atom as a bond is preferable, a cycloalkyl group in which the carbon atom of the bond is substituted with alkyl is more preferable, and a 2-alkyl-2-adamantyl group is more preferable. A 2-methyl-2-adamantyl group is particularly preferred.

The oxyhydrocarbon group is preferably an oxyalicyclic hydrocarbon group, more preferably a cycloalkyloxy group, and even more preferably an adamantyloxy group.

The aliphatic heterocyclic group is preferably an aliphatic heterocyclic group containing an oxygen atom as a ring constituent atom, more preferably an oxacycloalkyl group, and even more preferably an oxacyclohexyl group.

R ² is a hydrocarbon group, an oxyhydrocarbon group, an aliphatic heterocyclic ring, or the like from the viewpoint that the diffusion of the acid generated from the compound (I) is more appropriately suppressed by having bulkiness and / or polarity. Group and a β-diketone structure-containing group are preferable, and a hydrocarbon group is more preferable from the viewpoint of improving the solubility of the compound (I) in an organic solvent.

As the hydrocarbon group, an alkyl group and a cycloalkyl group are preferable, a cycloalkyl group is more preferable, a cyclopentyl group, a cyclohexyl group, an adamantyl group, and an adamantylmethyl group are more preferable, and a cyclopentyl group and a cyclohexyl group are particularly preferable.

The oxyhydrocarbon group is preferably a cycloalkyloxy group, and more preferably a cyclohexyloxy group.

The aliphatic heterocyclic group is preferably an aliphatic heterocyclic group containing a sulfur atom as a ring constituent atom, more preferably a dithiacycloalkyl group, and even more preferably a dithiacyclohexyl group.

As the β-diketone structure-containing group, a pentane-2,4-one-3-yl group is preferable.

At least one of R ¹ and R ² is preferably a group having a cyclic structure. When R ¹ and / or R ² has a cyclic structure, a sterically more crowded structure is formed in the vicinity of the sulfonate group of compound (I), and the diffusion of acid generated from compound (I) is more appropriately suppressed. Moreover, uneven distribution of the compound (I) in the surface layer in the resist film can be further suppressed. As a result, the LWR performance and MEEF performance of the radiation sensitive resin composition and the rectangularity of the cross-sectional shape of the resist pattern to be formed can be further improved. It is more preferable that both R ¹ and R ² are groups having a cyclic structure.

As said R < ³ >, R < ⁴ > and R < ⁵ >, a hydrogen atom and a monovalent hydrocarbon group are preferable, a hydrogen atom and an alkyl group are more preferable, and from a viewpoint of the synthetic | combination ease of a compound (I), a hydrogen atom Is more preferable.

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

The monovalent radiolytic 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 radiolytic onium cation and the sulfonate anion (A). Examples of the radiation include electromagnetic waves such as ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays and γ rays; charged particle rays such as electron rays and α rays. Among these, far ultraviolet rays, EUV, and electron beams are preferable, far ultraviolet rays are more preferable, KrF excimer laser light (248 nm) and ArF excimer laser light (193 nm) are more preferable, and ArF excimer laser light is particularly preferable.

Examples of the radiolytic onium cation include radiolytic onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. It is done. Among these, a sulfonium cation containing S (sulfur) as an element and an iodonium cation containing I (iodine) as an element are preferable, and a cation represented by the following formula (X-1) is represented by the following formula (X-2): A cation represented by the following formula (X-3) is more preferable.

In the above formula (X-1), R ^a1 , R ^a2 and R ^a3 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted group. aromatic hydrocarbon group having 6 to 12 carbon atoms, represents or is 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. When R ^a1 ~ ^{R a3} and ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{~ 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 to 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 to 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 to 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 aromatic hydrocarbon group having 1-12, indicating whether it is -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 each independently represent 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 n-butyl. Groups and the like.
Examples of the unsubstituted branched alkyl group represented by R ^a1 to R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an i-propyl group, i-butyl group, sec-butyl group, Examples thereof include t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^a1 to R ^a3 , R ^c1 and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group and naphthyl group; benzyl group And aralkyl groups such as a 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 substitute 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. 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.

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

Examples of the sulfonium cation include cations represented by the following formulas (i-1) to (i-68).

In addition, examples of the iodonium cation include cations represented by the following formulas (ii-1) to (ii-39).

Among these, the radiolytic onium cation is preferably a sulfonium cation represented by (i-1), an iodonium cation represented by (ii-1), and a sulfonium cation represented by (i-1). Is more preferable.

Examples of the compound (I) include compounds represented by the following formulas (1-1) to (1-24) (hereinafter also referred to as “compounds (I-1) to (I-24)”).

 

 

In the above formulas (1-1) to (1-24), M ⁺ is a monovalent radiolytic onium cation.

Of these, from the viewpoint of further improving the LWR performance, MEEF performance and rectangular shape of the cross-sectional shape of the radiation-sensitive resin composition, the compounds (I-1) to (I-17) are preferred, and the compound (I- 1), Compound (I-4), Compound (I-6), Compound (I-10), and Compound (I-14) are more preferable, and Compound (I-1) and Compound (I-6) are more preferable. .

<Method for Synthesizing Compound (I)>
For example, in the case of the compound (I ′) represented by the following formula (1 ′) in which R ⁵ in the above formula (1) is a hydrogen atom and n is 1, the compound (I) is synthesized according to the following scheme. can do.

In the above scheme, R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ and R ⁴ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. X is a halogen atom. M ⁺ is a monovalent radiolytic onium cation. Y ⁻ is a monovalent cation.

The compound represented by the above formula (b) is obtained by reacting the compound represented by the above formula (a) with a Grignard reagent having an R ² group in a solvent such as tetrahydrofuran. Next, this compound (b) is reacted with a sulfonating agent in a solvent such as water in the presence of a base to obtain a sulfonate represented by the above formula (c). Next, the compound (c) is reacted with a salt compound containing a monovalent radiolytic onium cation represented by the above formula M ⁺ Y ⁻ in a solvent such as dichloromethane / water, thereby the above formula (1). A compound represented by ') is obtained.

Examples of the sulfonating agent include sulfites such as sulfite gas, sodium sulfite, potassium sulfite, calcium sulfite, barium sulfite, and ammonium sulfite, bisulfites such as sodium bisulfite and potassium bisulfite, sodium dithionite, And dithionites such as potassium dithionite. Of these, sulfites are preferred, and sodium sulfite is more preferred.

Examples of the base include metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide, metal carbonates such as sodium carbonate, potassium carbonate, calcium carbonate, and magnesium carbonate, sodium bicarbonate, Metal hydrogen carbonates such as potassium hydrogen carbonate, trimetal phosphates such as trisodium phosphate and tripotassium phosphate, dihydrogen hydrogen phosphates such as disodium hydrogen phosphate and dipotassium hydrogen phosphate, diphosphate Examples thereof include metal dihydrogen phosphates such as sodium hydrogen and potassium dihydrogen phosphate, and organic bases such as triethylamine and pyridine. Among these, metal hydrogen carbonates are preferable, and sodium hydrogen carbonate is more preferable.

Compound (1) other than compound (1 ') can also be synthesized by the same method as described above.

[Other acid generators]
[B] The acid generator may contain an acid generator other than the compound (I) other than the compound (I) as long as the effects of the present invention are not impaired.

The other acid generator is not particularly limited as long as it is an acid generator other than the compound (I), and examples thereof include onium salt compounds and N-sulfonyloxyimide compounds.

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

Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4 -Cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Ruphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methane Sulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetraph Oroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) hexane-1-sulfonate, triphenylsulfonium 1,1- Difluoro-2- (adamantan-1-yl) ethane-1-sulfonate, triphenylsulfonium 1,1-difluoro-2- (adamantan-1-yloxycarbonyl) ethane-1-sulfonate, triphenylsulfonium 1,1- And difluoro-2- (adamantanyl-ylcarbonyloxy) ethane-1-sulfonate.

Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiofe Nitro 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-Butoxynaphthalen-2-yl Tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothio Phenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl- -Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4- Hydroxyphenyl) tetrahydrothiophenium camphorsulfonate and the like.

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

Examples of N-sulfonyloxyimide compounds include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoro-ethanone Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide and the like.

[B] The content of the acid generator is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 25 parts by weight, and more preferably 1 to 100 parts by weight of the [A] polymer. More preferred is 20 to 20 parts by mass. [B] By making content of an acid generator into the said range, the said radiation sensitive resin composition can raise a sensitivity, As a result, LWR performance, MEEF performance, and the rectangular property of cross-sectional shape are improved. be able to.

[B] The content of the compound (I) in the acid generator is preferably 20% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, further preferably 90% by mass to 100% by mass, Mass% is particularly preferred. By making the content rate of compound (I) into the said range, the said radiation sensitive resin composition can improve LWR performance, MEEF performance, and the rectangular shape of a cross-sectional shape more.

The content of the compound (I) in the radiation-sensitive resin composition is preferably 0.1 to 30 parts by mass, and 0.5 to 25 parts by mass with respect to 100 parts by mass of the [A] polymer. Part is more preferable, and 1 part by mass to 20 parts by mass is more preferable. By making content of compound (I) into the said range, the said radiation sensitive resin composition can further improve LWR performance, MEEF performance, and the rectangular shape of cross-sectional shape.

<[C] acid diffusion controller>
The said radiation sensitive resin composition may contain a [C] acid diffusion control agent as needed.
[C] The acid diffusion controlling agent controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, and has the effect of suppressing undesired chemical reaction in the non-exposed region, and the radiation sensitivity obtained. The storage stability of the photosensitive resin composition is further improved, the resolution of the resist is further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, thereby stabilizing the process. A radiation-sensitive resin composition having excellent properties can be obtained.

[C] Examples of the acid diffusion controller include a compound represented by the following formula (3) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”). , “Nitrogen-containing compound (II)”, compounds having three nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. Can be mentioned.

In the above formula (3), R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. .

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine and tri-n-pentylamine; aniline, And aromatic amines such as 2,6-di-i-propylaniline. Of these, trialkylamines and aromatic amines are preferable, and tri-n-pentylamine and 2,6-di-i-propylaniline are more preferable.

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

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

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

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

Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N- (undecylcarbonyloxyethyl) morpholine; imidazoles such as 2-phenylbenzimidazole. A pyrazine, a pyrazole, etc. are mentioned. Of these, N- (undecylcarbonyloxyethyl) morpholine is preferred.

In addition, as the nitrogen-containing organic compound, a compound having an acid dissociable group can also be used. Examples of such a nitrogen-containing organic compound having an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl- 2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) Examples thereof include diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like. Among these, Nt-butoxycarbonyl-4-hydroxypiperidine and Nt-amyloxycarbonyl-4-hydroxypiperidine are preferable, and Nt-butoxycarbonyl-4-hydroxypiperidine is more preferable.

Further, as the [C] acid diffusion control agent, a photodegradable base that is exposed to light and generates a weak acid upon exposure can also be used. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (4), an iodonium salt compound represented by the following formula (5), and the like.

In the above formulas (4) and (5), R ¹⁵ to R ¹⁹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ⁻ and Q ⁻ are each independently OH ⁻ , R ^β —COO ⁻ , R ^β —SO ₃ ^— or an anion represented by the following formula (X). However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (X), R ²⁰ represents a linear or branched alkyl group having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 12 carbon atoms. These are linear or branched alkoxyl groups. u is an integer of 0-2.

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

Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate or triphenylsulfonium 10-camphorsulfonate.

[C] The content of the acid diffusion controller is preferably from 0 to 20 parts by weight, more preferably from 0.1 to 15 parts by weight, more preferably from 0.1 to 15 parts by weight, based on 100 parts by weight of the [A] polymer. More preferably, 3 parts by mass to 10 parts by mass. [C] When the content of the acid diffusion controller exceeds the upper limit, the sensitivity of the radiation-sensitive resin composition may be lowered.

<[D] Polymer>
[D] The polymer is a fluorine atom-containing polymer (except for those corresponding to the [A] polymer). When the radiation-sensitive resin composition contains the [D] polymer, when the resist film is formed, the distribution is near the resist film surface due to the oil-repellent characteristics of the fluoropolymer 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 [D] polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, when the said radiation sensitive resin composition contains a [D] polymer, the resist film suitable for an immersion exposure method can be formed.

[D] The polymer is not particularly limited as long as it is a polymer having a fluorine atom, but the fluorine atom content (% by mass) is higher than that of the [A] polymer in the radiation-sensitive resin composition. It is preferable. [A] When the fluorine atom content is higher than that of the polymer, the degree of uneven distribution described above becomes higher, and characteristics such as water repellency and elution suppression of the resulting resist film are improved.

[D] 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 more preferably 7% by mass to 30% by mass. Particularly preferred. [D] If the fluorine atom content of the polymer is less than the lower limit, the hydrophobicity of the resist film surface may be lowered. The fluorine atom content (% by mass) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement.

[D] The polymer preferably has at least one selected from the group consisting of the following structural unit (Da) and structural unit (Db). [D] The polymer may have one or more structural units (Da) and structural units (Db).

[Structural unit (Da)]
The structural unit (Da) is a structural unit represented by the following formula (6a). [D] A polymer can adjust a fluorine atom content rate by having a structural unit (Da).

In said formula (6a), ^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 chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom. It is.

The chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom 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 Examples thereof include n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like.

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom represented by R ^E, for example, monofluoromethyl cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl , Difluorocyclopentyl group, perfluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, fluorotetracyclodecyl group and the like.

Examples of the monomer that gives the structural unit (Da) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and 2,2,2-trifluoro. Ethyloxycarbonylmethyl (meth) acrylic acid ester, perfluoroethyl (meth) acrylic acid ester, perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (Meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (Meth) acrylic acid ester, 1- (2,2,3,3,4,4,5,5-octaful Lopentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, monofluorocyclopentyl (meth) Acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic Acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl Meth) acrylic acid esters, fluoro tricyclodecyl (meth) acrylate, fluoro tetracyclododecene decyl (meth) acrylic acid ester.
Of these, 2,2,2-trifluoroethyloxycarbonylmethyl (meth) acrylic acid ester is preferred.

The content ratio of the structural unit (Da) is preferably 5 mol% to 95 mol%, more preferably 10 mol% to 90 mol%, and more preferably 25 mol% with respect to all the structural units constituting the [D] polymer. More preferred is ˜80 mol%. By setting such a content ratio, a higher dynamic contact angle on the resist film surface can be expressed at the time of immersion exposure.

[Structural unit (Db)]
The structural unit (Db) is a structural unit represented by the following formula (6b). Since the [D] polymer has the structural unit (Db) and becomes hydrophobic, the dynamic contact angle of the resist film surface formed from the radiation-sensitive resin composition can be further improved.

In said formula (6b), R ^<F> is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ²¹ is an (s + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, —NR′—, a carbonyl group, —CO—O—, or a terminal at the R ²² side of R ²¹ Also includes a structure in which —CO—NH— is bonded. R ′ is a hydrogen atom or a monovalent organic group. R ²² is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a C 1-20 divalent chain hydrocarbon group having at least one fluorine atom. A ¹ is an oxygen atom, —NR ″ —, —CO—O— *, or —SO ₂ —O— *. R ″ is a hydrogen atom or a monovalent organic group. * ^Indicates a binding site that binds to ^{R 21.} R ²³ is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, a plurality of R ²² , X ² , A ¹ and R ²³ may be the same or different.

When R ²³ is a hydrogen atom, it is preferable in that the solubility of [D] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ²³ include an acid dissociable group, an alkali dissociable group, or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

Examples of the structural unit (Db) include structural units represented by the following formulas (6b-1) to (6b-3).

In the above formulas (6b-1) to (6b-3), R ^{21 ′} is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ^F , X ² , R ²³ and s are as defined in the above formula (6b). When s is 2 or 3, the plurality of X ² and R ²³ may be the same or different.

The content of the structural unit (6b) is preferably 0 mol% to 90 mol%, more preferably 5 mol% to 85 mol%, more preferably 10 mol based on all structural units constituting the [D] polymer. % To 80 mol% is more preferable. By setting it as such a content rate, the resist film surface formed from the said radiation sensitive resin composition can improve the fall degree of a dynamic contact angle in alkali image development.

[Structural unit (Dc)]
[D] The polymer may have a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (Dc)”) in addition to the structural units (Da) and (Db) ( However, those corresponding to the structural unit (Db) are excluded). [D] When the polymer has the structural unit (Dc), the shape of the resulting resist pattern becomes better. Examples of the structural unit (Dc) include the structural unit (II) in the above-described [A] polymer.

The content ratio of the structural unit (Dc) is preferably 5 mol% to 90 mol%, more preferably 10 mol% to 80 mol%, more preferably 15 mol% with respect to all the structural units constituting the [D] polymer. More preferred is ˜75 mol%. If the content ratio of the structural unit (Dc) is less than the lower limit, development defects in the resist pattern may not be sufficiently suppressed. When the content ratio of the structural unit (Dc) exceeds the upper limit, the hydrophobicity of the resulting resist film surface may be lowered.

[Other structural units]
In addition to the above structural unit, the [D] polymer includes, for example, a structural unit containing at least one structure selected from the group consisting of a structural unit containing an alkali-soluble group, a lactone structure, a cyclic carbonate structure, and a sultone structure. And may have other structural units such as a structural unit containing an alicyclic group. As said alkali-soluble group, a carboxy group, a sulfonamide group, a sulfo group etc. are mentioned, for example. Examples of the structural unit having at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure include the structural unit (III) in the above-described [A] polymer.

The content ratio of the other structural units is usually 30 mol% or less, preferably 20 mol% or less, based on all the structural units constituting the [D] polymer. When the content rate of said other structural unit exceeds the said upper limit, the pattern formation property of the said radiation sensitive resin composition may fall.

The content of the [D] polymer in the radiation sensitive resin composition is preferably 0 to 20 parts by mass, and 0.5 to 15 parts by mass with respect to 100 parts by mass of the [A] polymer. More preferred is 1 to 10 parts by mass. [D] If the content of the polymer exceeds the above upper limit, the pattern-forming property of the radiation-sensitive resin composition may be lowered.

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

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

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

As an ether solvent, for example,
Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl 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 ketone solvents include acetone, butanone, 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 and methylcyclohexanone:
Examples include 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

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:
Methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxy acetate Acetate solvents such as butyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol partial ether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Carbonate solvents such as dimethyl carbonate and diethyl carbonate;
Diethyl acetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetoacetate, methyl lactate, ethyl lactate N-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

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

Among these, ester solvents and ketone solvents are preferable, polyhydric alcohol partial ether acetate solvents and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are more preferable. The radiation-sensitive resin composition may contain one or more [E] solvents.

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

(Uniformity promoting agent)
The uneven distribution accelerator has an effect of segregating the [D] polymer on the resist film surface more efficiently when the radiation-sensitive resin composition contains the [D] polymer. By including this uneven distribution accelerator in the radiation sensitive resin composition, the amount of the [D] polymer added can be reduced as compared with the conventional case. Therefore, it is possible to further suppress the elution of components from the resist film to the immersion liquid without damaging the basic resist characteristics such as LWR, development defects, and pattern collapse resistance, and to perform immersion exposure at a higher speed by high-speed scanning. As a result, the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects can be improved. Examples of such an uneven distribution promoter include low molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point at 1 atm of 100 ° C. or more. Specific examples of such compounds include lactone compounds, cyclic carbonate compounds, nitrile compounds, and polyhydric alcohols.

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

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

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

Among these, the ubiquitous accelerator is preferably a lactone compound or a cyclic carbonate compound, more preferably a lactone compound, and even more preferably γ-butyrolactone.

The content of the uneven distribution accelerator is preferably 10 parts by weight to 500 parts by weight, and more preferably 10 parts by weight to 300 parts by weight with respect to 100 parts by weight of the total amount of the polymer in the radiation sensitive resin composition. 10 parts by weight to 150 parts by weight is more preferable.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industrial Co., Ltd.) Can be mentioned. As content of 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 deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as tert-butyl lithocholic acid, tert-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>
The radiation sensitive resin composition includes, for example, [A] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer, and [E] solvent as required. It can prepare by mixing in the ratio. The radiation-sensitive resin composition is preferably filtered after mixing with, for example, a filter having a pore size of about 0.05 μm. The solid content concentration of the radiation-sensitive resin composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

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

According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, a resist pattern having a small LWR can be formed. Hereinafter, each step will be described.

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

When immersion exposure is performed and the radiation-sensitive resin composition does not contain a water-repellent polymer additive, the direct immersion of the immersion liquid and the resist film is performed on the formed resist film. In order to avoid contact, an immersion protective film that is insoluble in the immersion liquid may be provided. As the protective film for immersion, a solvent-peeling protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), a developer-peeling protective film that peels off simultaneously with development in the development process (For example, refer to WO 2005-069096 and WO 2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

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

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

After the exposure, post-exposure baking (PEB) is performed, and in the exposed portion of the resist film, dissociation of the acid-dissociable group of the [A] polymer or the like by the acid generated from the [B] acid generator by exposure. Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. The PEB temperature is usually 50 ° C. to 180 ° C., preferably 80 ° C. to 130 ° C. The PEB time is usually 5 to 600 seconds, and preferably 10 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,
For alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine , Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4 .3.0] -5-nonene, an alkaline aqueous solution in which at least one alkaline compound is dissolved, and the like. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.
In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents can be mentioned. As said organic solvent, 1 type (s) or 2 or more types of the solvent enumerated as [E] solvent of the above-mentioned radiation sensitive resin composition are mentioned, for example. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. The ketone solvent is preferably a chain ketone, more preferably 2-heptanone. 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.

<Radiation sensitive acid generator>
The said radiation sensitive acid generator contains compound (I).
The said radiation sensitive acid generator can improve the LWR performance of the radiation sensitive resin composition containing this, MEEF performance, and the rectangular shape of a cross-sectional shape. Therefore, the radiation sensitive acid generator can be suitably used as a component of the radiation sensitive resin composition.

<Compound>
The said compound is the said compound (I).
Since the said compound has the above-mentioned property, it can be used suitably as the said radiation sensitive acid generator.

The radiation-sensitive acid generator and the compound are described above in the section [B] Acid generator of the radiation-sensitive resin composition.

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

[ ¹ H-NMR analysis, ¹³ C-NMR analysis and ¹⁹ F-NMR analysis]
Analysis was performed using a nuclear magnetic resonance apparatus (“JNM-EX400” manufactured by JEOL Ltd.) using deuterated chloroform as a measurement solvent.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Monodispersed polystyrene using Tosoh's GPC columns (G2000HXL: 2, G3000HXL: 1, G4000HXL: 1), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C. Was measured by gel permeation chromatography (GPC). The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

<Synthesis of Compound (I)>
[Example 1] (Synthesis of Compound (B-1))
(1) Synthesis of Compound (Sb) A 300 mL three-necked reactor equipped with a dropping funnel and dried was placed in an argon atmosphere, and then charged with a 30 mL hexane solution of 8.91 g (51.4 mmol) of cyclopentylmagnesium bromide, While stirring with a magnetic stirrer, 3.25 mL (25.7 mmol) of chlorotrimethylsilane and 40 mL of tetrahydrofuran (THF) were added, and the mixture was stirred at 0 ° C. for 30 minutes. Thereto was added dropwise a 30 mL THF solution of 7.41 g (25.7 mmol) of a compound represented by the following formula (Sa). After confirming the completion of the reaction by gas chromatography, an aqueous ammonium chloride solution was added and stirred for 1 hour to stop the reaction. The obtained liquid was filtered through Celite to remove insoluble matters. Next, after extracting with ethyl acetate and separating the aqueous layer and the organic layer, the organic layer was washed with an aqueous sodium bicarbonate solution. The obtained organic layer was dried and concentrated under reduced pressure, followed by recrystallization purification to obtain 2.00 g of a compound represented by the following formula (Sb) as a white solid (yield 23%, purity 99%). Obtained.

(2) Synthesis of Compound (Sc) After a 200 mL eggplant reactor equipped with a condenser was placed in an argon atmosphere, 2.80 g (17.7 mmol) of sodium sulfite as a sulfonating agent and 20 mL of water were charged. While stirring with a magnetic stirrer, a solution of 2.00 g (5.91 mmol) of the compound (Sb) synthesized above in 60 mL of methanol and 0.60 g (7.09 mmol) of sodium bicarbonate were added, and the mixture was added at 60 ° C. to 70 ° C. Stir for 2 hours at ° C. After confirming the completion of the reaction by ¹⁹ F-NMR, the mixture was extracted with dichloromethane, and the aqueous layer and the organic layer were separated. The obtained organic layer was dried and concentrated under reduced pressure, and then recrystallized to obtain 0.92 g (yield 35%, purity 99%) of a compound represented by the following formula (Sc) as a white solid. Obtained.

 

(3) Synthesis of Compound (B-1) A 100 mL eggplant reactor was placed in an argon atmosphere, and then 0.62 g (2.07 mmol) of triphenylsulfonium chloride and 7 mL of water were charged and stirred with a magnetic stirrer. A solution of 0.92 g (2.07 mmol) of the compound (Sc) obtained above in 20 mL of dichloromethane was added and stirred at 20 to 30 ° C. for 2 hours. After confirming the completion of the reaction by ¹⁹ F-NMR, the mixture was extracted with dichloromethane, and the aqueous layer and the organic layer were separated. The organic layer was dried and concentrated under reduced pressure, followed by recrystallization purification to obtain 1.2 g (yield 85%, purity 99%) of a compound represented by the following formula (B-1) as a white solid.

¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.66-7.80 (m, 15H), 2.75-2.78 (t, 1H), 1. 94-1.98 (m, 1H), 1.79-1.83 (m, 3H), 1.58-1.69 (m, 8H), 1.48-1.56 (m, 10H), 1.33-1.43 (m, 2H), 1.16-1.20 (m, 2H), 0.88-0.92 (m, 2H).

[Examples 2 to 17] (Synthesis of compounds (B-2) to (B-17))
The compounds represented by the following formulas (B-2) to (B-17) were obtained in the same manner as in Example 1.
¹ H-NMR analysis (measurement solvent: deuterated chloroform, reference material: tetramethylsilane) data is shown below.

Compound (B-2); δ = 7.66-7.80 (m, 15H), 2.75-2.78 (t, 1H), 2.00-2.04 (m, 3H), 1. 79-1.83 (m, 3H), 1.66-1.77 (m, 12H), 1.48-1.59 (m, 9H), 1.33-1.43 (m, 2H), 1.14-1.21 (m, 3H), 0.90-0.94 (m, 2H).

Compound (B-3); δ = 7.66-7.80 (m, 15H), 2.75-2.78 (t, 1H), 2.29-2.33 (m, 2H), 2. 12-2.15 (m, 2H), 1.68-1.88 (m, 8H), 1.59-1.63 (m, 5H), 1.47-1.50 (m, 3H), 1.26-1.33 (m, 5H), 0.81-0.84 (t, 3H).

Compound (B-4); δ = 7.66-7.80 (m, 15H), 4.21-4.25 (m, 1H), 2.75-2.78 (t, 1H), 2. 44-2.48 (m, 2H), 1.85-1.89 (m, 2H), 1.71-1.81 (m, 10H), 1.52-1.64 (m, 10H), 1.46-1.50 (m, 1H).

Compound (B-5); δ = 7.66-7.80 (m, 15H), 3.89-3.93 (m, 1H), 2.75-2.78 (t, 1H), 1. 78-1.82 (m, 4H), 1.55-1.62 (m, 10H), 1.47-1.54 (m, 7H).

Compound (B-6); δ = 7.66-7.80 (m, 15H), 3.38-3.42 (t, 1H), 3.09-3.13 (m, 1H), 2. 17-2.21 (m, 2H), 1.74-1.89 (m, 12H), 1.48-1.62 (m, 9H), 1.36-1.40 (m, 2H).

Compound (B-7); δ = 7.66-7.80 (m, 15H), 1.84-2.02 (m, 4H), 1.69-1.81 (m, 12H), 1. 48-1.62 (m, 9H), 1.19-1.23 (t, 2H).

Compound (B-8); δ = 7.66-7.80 (m, 15H), 4.21-4.25 (m, 1H), 3.96-4.00 (m, 1H), 2. 75-2.78 (t, 1H), 2.33-2.48 (m, 4H), 1.85-2.03 (m, 8H), 1.72-1.80 (m, 10H), 1.54-1.58 (m, 4H).

Compound (B-9); δ = 7.66-7.80 (m, 15H), 4.21-4.25 (m, 1H), 3.83-3.87 (d, 2H), 3. 18-3.22 (t, 1H), 2.77-2.81 (m, 1H), 2.44-2.48 (m, 2H), 1.74-1.89 (m, 12H), 1.68-1.72 (m, 4H), 1.47-1.55 (m, 6H).

Compound (B-10); δ = 7.66-7.80 (m, 15H), 1.98-2.02 (m, 1H), 1.56-1.61 (m, 8H), 1. 51-1.55 (m, 8H), 1.41-1.49 (m, 2H).

Compound (B-11); δ = 7.66-7.80 (m, 15H), 1.85-2.15 (m, 1H), 1.45-1.55 (m, 12H), 1. 25-1.40 (m, 10H), 1.19-1.23 (m, 2H).

Compound (B-12); δ = 7.66-7.80 (m, 15H), 1.95-2.05 (m, 1H), 1.82-1.92 (m, 6H), 1. 67-1.77 (m, 24H), 1.12-1.30 (m, 6H).

Compound (B-13); δ = 7.66-7.80 (m, 15H), 1.85-2.15 (m, 1H), 1.57-1.67 (m, 1H), 1. 37-1.55 (m, 15H), 1.16-1.32 (m, 8H), 0.88-0.94 (d, 6H).

Compound (B-14); δ = 7.66-7.80 (m, 15H), 3.50-3.70 (m, 4H), 1.85-2.15 (m, 1H), 1. 55-1.74 (m, 7H), 1.29-1.51 (m, 7H), 1.18-1.24 (t, 2H).

Compound (B-15); δ = 7.66-7.80 (m, 15H), 7.22-7.35 (m, 5H), 3.27-3.33 (m, 1H), 1. 49-1.55 (m, 2H), 0.73-0.79 (t, 3H).

Compound (B-16); δ = 7.66-7.80 (m, 15H), 3.54-3.60 (t, 1H), 2.34-2.54 (m, 4H), 1. 90-2.09 (m, 5H), 1.41-1.65 (m, 7H), 1.29-1.39 (m, 2H).

Compound (B-17); δ = 7.66-7.80 (m, 15H), 3.18-3.24 (t, 1H), 2.31 (s, 6H), 1.85-2. 15 (m, 1H), 1.74-1.80 (t, 2H), 1.29-1.65 (m, 9H).

 

 

<Synthesis of polymer>
The compound (monomer) used for the synthesis of [A] polymer and [D] polymer is shown below.

[[A] Synthesis of polymer]
[Synthesis Example 1] (Synthesis of polymer (A-1))
21.12 g (55 mol%) of the above compound (M-1), 3.84 g (10 mol%) of the compound (M-3) and 13.44 g (35 mol%) of the compound (M-5) were mixed with 80 g of 2- A monomer solution was prepared by dissolving in butanone and further adding 3.54 g of AIBN. Next, a 200 mL three-necked flask containing 40 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. Subsequently, after completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization reaction liquid was put into 800 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 160 g of methanol, filtered and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (yield 29.18 g, yield). (Rate 76%). Mw of the polymer (A-1) was 4,500, and Mw / Mn was 1.4. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-3) and (M-5) was 54 mol%, 11 mol% and 35 mol%, respectively. Met.

[Synthesis Example 2] (Synthesis of Polymer (A-2))
A polymer (A-2) was synthesized in the same manner as in Synthesis Example 1 except that the types and amounts of monomers shown in Table 1 were used. The total mass of the monomers used was the same as in Synthesis Example 1. The yield, Mw and Mw / Mn values of the obtained polymer (A-2) are shown in Table 1.

[[D] Synthesis of polymer]
[Synthesis Example 3] (Synthesis of Polymer (D-1))
14.3 g (30 mol%) of the compound (M-4) and 45.7 g (70 mol%) of the compound (M-6) were dissolved in 60 g of 2-butanone, and 3 g of AIBN was further added to obtain a monomer solution. Prepared. A 300 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reactor was heated to 80 ° C. with stirring, and the monomer solution was added dropwise over 3 hours using a dropping funnel. . The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization reaction, the polymerization reaction liquid was cooled to 30 ° C. or less by water cooling, and charged into 600 g of a mixture of methanol: water (8: 2 (mass ratio)) to precipitate the polymer. After removing the supernatant solution, 120 g of methanol was added to the precipitated polymer to wash the polymer. After removing the supernatant, it was dried at 50 ° C. for 17 hours to synthesize a polymer (D-1). Mw of the polymer (D-1) was 4,200, and Mw / Mn was 1.3. As a result of ¹³ C-NMR analysis, the fluorine atom content was 5% by mass, and the content ratios of structural units derived from (M-4) and (M-6) were 32.0 mol% and 68%, respectively. 0.0 mol%.

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

[[B] acid generator]
[B] Acid generator used in Examples: Compounds (B-1) to (B-17) synthesized above
Acid generator used in comparative examples: compounds represented by the following formulas (b-1) to (b-3)

[[C] acid diffusion controller]
C-1 to C-6: Compounds represented by the following formulas (C-1) to (C-6)

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

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

[Example 18]
[A] 100 parts by mass of (A-1) as a polymer, [B] 15 parts by mass of (B-1) as an acid generator, [C] 1.1 (C-1) as an acid diffusion controller Parts by weight, (D-1) 7 parts by weight as a [D] polymer, (E-1) 2,590 parts by weight and (E-2) 1,110 parts by weight as a solvent, and [F] ] 15 parts by mass of (F-1) as an uneven distribution promoter was mixed, and the obtained mixed solution was filtered through a filter having a pore diameter of 0.20 μm to prepare a radiation sensitive resin composition (J-1).

[Examples 19 to 56 and Comparative Examples 1 to 3]
Except that the components of the types and contents shown in Table 2 below were used, the same operations as in Example 18 were carried out to prepare radiation sensitive resin compositions (J-2) to (J-39) and (CJ-1 ) To (CJ-3) were prepared.

<Formation of resist pattern>
An antireflection film having a film thickness of 105 nm was formed on the surface of a 12-inch silicon wafer using a composition for forming an antireflection film (“ARC66” manufactured by Nissan Chemical Industries, Ltd.). On the antireflection film, the prepared radiation sensitive resin composition was applied, and SB was performed at 115 ° C. for 45 seconds to form a resist film having a thickness of 95 nm. Next, this resist film is formed using an ArF excimer laser immersion exposure apparatus ("NSR S610C" manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.800, Annular for 40 nm line 80 nm pitch formation. It exposed through the mask pattern. After exposure, PEB was performed at 100 ° C. for 45 seconds. Thereafter, development was performed with a 2.38 mass% TMAH aqueous solution, washed with water, and dried to form a line-and-space positive resist pattern. When this resist pattern is formed, the exposure amount formed in a one-to-one line-and-space with a line width of 40 nm is defined as the optimum exposure amount through a one-to-one line-and-space mask with a target dimension of 40 nm. did. The length of the resist pattern was measured using a scanning electron microscope (“CG4000” manufactured by Hitachi High-Technologies Corporation).

<Evaluation>
About each prepared said radiation sensitive resin composition, the sensitivity, LWR performance, MEEF performance, and the rectangularity of the cross-sectional shape of the resist pattern formed were evaluated in accordance with the following method. The evaluation results are shown in Table 3.

[sensitivity]
The optimum exposure amount obtained above was taken as sensitivity. The sensitivity can be evaluated as “A (good)” when it is 50 mJ / cm ² or less, and “B (bad)” when it exceeds 50 mJ / cm ² .

[LWR performance]
The formed resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, a value three times the standard deviation was calculated from the distribution of the measured values, and the calculated value was defined as LWR performance (nm). The LWR performance can be evaluated as “A (good)” when the thickness is 5.5 nm or less, and “B (defective)” when the thickness exceeds 5.5 nm.

[MEEF performance]
Five types of mask sizes (48.0 nm Line / 100 nm Pitch, 49.0 nm Line / 100 nm Pitch, 50.0 nm Line / 100 nm Pitch, 51.0 nm Line / 100 nm Pitch, 52.0 nm Line / 100 nm Pitch) at the optimum exposure dose using the scanning electron microscope. The line width of the resist pattern resolved in (1) was measured. The measured values obtained were plotted with the horizontal axis as the mask size and the vertical axis as the line width formed with each mask size, and the slope of the approximate straight line calculated by the least square method was obtained, and this slope was defined as MEEF performance. The MEEF performance indicates that the closer the value is to 1, the better. When the MEEF performance is 4.7 or less, it can be evaluated as “A (good)”, and when it exceeds 4.7, it can be evaluated as “B (defective)”.

[Rectangularity of cross-sectional shape]
Using the scanning electron microscope, the resist pattern was observed, the line width x above the pattern and the line width y below the pattern were measured, and the value of these ratios x / y was calculated. This x / y value was measured for a total of 10 arbitrary points of the resist pattern, and an arithmetic average value ([x / y]) of these points was obtained and used as an index of the rectangularity of the cross-sectional shape. The rectangularity of the cross-sectional shape is “A (good)” when 0.9 ≦ [x / y] ≦ 1.1, and [x / y] <0.9 or 1.1 <[x / y]. ) Can be evaluated as “B (defect)”.

As is clear from the results in Table 3, according to the radiation sensitive resin compositions of the examples, the LWR performance, the MEEF performance and the rectangular shape of the cross-sectional shape are all good, whereas the radiation sensitivity of the comparative example In the resin composition, the LWR performance, the MEEF performance, and the rectangular shape of the cross-sectional shape were all poor.

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 having a small LWR and excellent cross-sectional rectangularity while exhibiting excellent MEEF performance. The radiation sensitive acid generator of this invention can be used suitably as a component of the said radiation sensitive resin composition. The compound of the present invention can be suitably used as the radiation sensitive acid generator. Therefore, these can be suitably used in forming a pattern in a lithography process for various electronic devices such as semiconductor devices and liquid crystal devices.

Claims (13)

1. A polymer having a structural unit containing an acid-dissociable group, and a radiation-sensitive acid generator,
   The radiation sensitive resin composition in which the said radiation sensitive acid generator contains the compound represented by following formula (1).
   

   

   
   (In formula (1), R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom. Or a monovalent organic group having 1 to 20 carbon atoms, wherein R ¹ to R ⁵ are each a ring having 1 to 20 carbon atoms, which is composed of two or more of these together with the carbon atom to which they are bonded. (It may represent a part of the structure. N is an integer of 1 to 4. M ⁺ is a monovalent radiolytic onium cation.)
2. The radiation sensitive resin composition according to claim 1, wherein at least one of R ¹ and R ² in the formula (1) is a group having a cyclic structure.
3. The radiation sensitive resin composition according to claim 1, wherein n is 1.
4. The radiation sensitive resin composition according to claim 1, wherein R ⁵ is a hydrogen atom.
5. The radiation sensitive resin composition according to claim 1, wherein R ³ and R ⁴ are hydrogen atoms.
6. The radiation sensitive resin composition according to claim 1, wherein R ² is a hydrocarbon group.
7. The radiation sensitive resin composition according to claim 1, wherein R ¹ is a hydrocarbon group.
8. The radiation sensitive resin composition according to claim 1, wherein both R ¹ and R ² in the formula (1) are groups having a cyclic structure.
9. The radiation-sensitive resin composition according to claim 1, wherein the M ⁺ radiolytic onium cation is a sulfonium cation or an iodonium cation.
10. 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).
    

    

    
    (In the formula (2), R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁷ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or 3 to 3 carbon atoms. And R ⁸ and R ⁹ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent chain group having 3 to 20 carbon atoms. (It represents an alicyclic hydrocarbon group or an alicyclic structure having 3 to 20 carbon atoms, which is formed together with carbon atoms to which these groups are combined with each other)
11. Forming a resist film;
    A step of exposing the resist film, and a step of developing the exposed resist film,
    A method for forming a resist pattern, wherein the resist film is formed from the radiation-sensitive resin composition according to claim 1.
12. The radiation sensitive acid generator containing the compound represented by following formula (1).
    

    

    (In formula (1), R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom. Or a monovalent organic group having 1 to 20 carbon atoms, wherein R ¹ to R ⁵ are each a ring having 1 to 20 carbon atoms, which is composed of two or more of these together with the carbon atom to which they are bonded. (It may represent a part of the structure. N is an integer of 1 to 4. M ⁺ is a monovalent radiolytic onium cation.)
13. A compound represented by the following formula (1).
    

    

    
    (In formula (1), R ¹ and R ² are each independently a monovalent organic group having 1 to 20 carbon atoms. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom. Or a monovalent organic group having 1 to 20 carbon atoms, wherein R ¹ to R ⁵ are each a ring having 1 to 20 carbon atoms, which is composed of two or more of these together with the carbon atom to which they are bonded. (It may represent a part of the structure. N is an integer of 1 to 4. M ⁺ is a monovalent radiolytic onium cation.)