JPWO2014046097A1 - Photoresist composition, resist pattern forming method, and acid generator - Google Patents

Abstract

This invention is a photoresist composition containing the acid generator containing the polymer which has a structural unit containing an acid dissociable group, and the compound represented by following formula (1). In the following formula (1), R1 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R2 is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number. Q + is a monovalent photodegradable organic cation.

Description

  The present invention relates to a photoresist composition, a resist pattern forming method, and an acid generator.

  In the field of microfabrication typified by the manufacture of integrated circuit elements, conventionally, a resist film is formed on a substrate using a photoresist composition containing a polymer having an acid-dissociable group, and the resist film is formed through a mask pattern. The resist film is exposed to short wavelength exposure light such as excimer laser light, and the exposed portion is removed with a developer to form a fine resist pattern. At this time, a chemically amplified resist in which an acid generator that generates an acid upon exposure is contained in the photoresist composition and the sensitivity is improved by the action of the acid is used. However, with the progress of lithography technology such as higher integration of integrated circuits and higher speed, a photoresist composition capable of forming a finer resist pattern has been demanded. As a result, the photoresist composition not only has the above resolution, but also has excellent rectangularity of the cross-sectional shape of the pattern, and MEEF (mask error enhancement factor) performance indicating the dependence of the pattern width on the mask dimension. Are also required to be superior.

  In response to such demands, photoresist compositions containing various acid generators have been developed (see Japanese Patent Application Laid-Open No. 2007-145803 and International Publication No. 2011/104127). However, at the present time when the miniaturization of resist patterns is progressing, MEEF performance is required to be more excellent. Moreover, about the said photoresist composition, the resist pattern formed tends to become top loss etc., and the rectangularity of the cross-sectional shape is not enough. Furthermore, the resist pattern is also required to have excellent etching resistance as the resist film becomes thinner.

JP 2007-145803 A International Publication No. 2011/104127

  This invention is made | formed based on the above situations, The objective is providing the photoresist composition which can form the resist pattern which was excellent in MEEF performance, and was excellent in the cross-sectional rectangularity and etching resistance. There is.

（式（１）中、Ｒ^１は、置換若しくは非置換の炭素数１〜３０の１価の炭化水素基又は置換若しくは非置換の環原子数３〜３０の１価の複素環基である。Ｒ^２は、炭素数１〜３０のアルカンジイル基又はフッ素数が炭素数よりも小さい炭素数２〜３０のフッ素化アルカンジイル基である。Ｑ^＋は、１価の光分解性有機カチオンである。）The invention made to solve the above problems is
A polymer having a structural unit containing an acid dissociable group (hereinafter also referred to as “[A] polymer”), and a compound represented by the following formula (1) (hereinafter also referred to as “compound (1)”). ) Containing an acid generator (hereinafter also referred to as “[B] acid generator”).
Is a photoresist composition containing

(In Formula (1), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number, Q ⁺ is a monovalent photodegradable organic cation. .)

Another invention made to solve the above problems is as follows:
Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
This is a resist pattern forming method in which the resist film is formed from the photoresist composition.

（式（１）中、Ｒ^１は、置換若しくは非置換の炭素数１〜３０の１価の炭化水素基又は置換若しくは非置換の環原子数３〜３０の１価の複素環基である。Ｒ^２は、炭素数１〜３０のアルカンジイル基又はフッ素数が炭素数よりも小さい炭素数２〜３０のフッ素化アルカンジイル基である。Ｑ^＋は、１価の光分解性有機カチオンである。）Another invention made to solve the above problems is as follows:
It is an acid generator containing the compound represented by following formula (1).

(In Formula (1), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number, Q ⁺ is a monovalent photodegradable organic cation. .)

  Here, the “hydrocarbon group” refers to a group composed of a carbon atom and a hydrogen atom, and includes “chain hydrocarbon group”, “alicyclic hydrocarbon group” and “aromatic hydrocarbon group”. being classified. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure and is composed only of a chain structure. The “alicyclic hydrocarbon group” refers to a hydrocarbon group containing only an alicyclic structure as a ring structure. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include an alicyclic structure or a chain structure. The chain hydrocarbon group and the chain structure may be linear or branched.

  “Heterocyclic group” refers to a group having a ring structure similar to an alicyclic hydrocarbon group or aromatic hydrocarbon group, and containing an atom other than carbon as a ring-constituting atom. Examples of atoms other than carbon include one or more heteroatoms such as sulfur, nitrogen, and oxygen. The heterocyclic group may be monocyclic, polycyclic, aromatic heterocyclic group, or aliphatic heterocyclic group. However, it is not necessary to be composed only of a heterocyclic structure, and a part thereof may include an alicyclic structure, an aromatic ring structure, a chain structure, or the like. The chain structure may be linear or branched.

  According to the photoresist composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern that is excellent in cross-sectional rectangularity and etching resistance while exhibiting excellent MEEF performance. Further, the acid generator of the present invention can be suitably used as a component of the photoresist composition. 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.

<Photoresist composition>
The photoresist composition contains a [A] polymer and a [B] acid generator. The photoresist composition may contain a [C] acid diffusion controller, a [D] fluorine atom-containing polymer, and a [E] solvent as suitable components, as long as the effects of the present invention are not impaired. [F] You may contain other arbitrary components, such as an uneven distribution promoter. 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)”). Due to the action of an acid generated from the [B] acid generator described later, the solubility of the [A] polymer in the developer changes. For this reason, the [A] polymer usually functions as a base polymer. The “base polymer” refers to a polymer that is a main component of a polymer that forms a resist pattern formed from a photoresist composition, and preferably 50% of the total polymer that forms the resist pattern. A polymer occupying at least mass%.

  [A] The polymer is a structural unit having at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure in addition to the structural unit (I) as long as the effects of the present invention are not impaired (hereinafter referred to as the structural unit). , Also referred to as “structural unit (II)”). [A] The polymer may have one or two or more of these structural units. [A] The polymer may be a random copolymer or a block copolymer.

<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. The “acid-dissociable group” refers to a group that replaces a hydrogen atom such as a hydroxy group or a carboxy group and dissociates in the presence of an acid. Thereby, the said structural unit will produce a polar group by the effect | action of an acid.

  Examples of the acid dissociable group include a t-butoxycarbonyl group, a tetrahydropyranyl group, a tetrahydrofuranyl group, a (thiotetrahydropyranylsulfanyl) methyl group, and a (thiotetrahydrofuranylsulfanyl) group that replaces a hydrogen atom of a hydroxy group. Examples thereof include a methyl group, an alkoxy-substituted methyl group, and an alkylsulfanyl-substituted methyl group. Examples of the group that substitutes a hydrogen atom of a carboxy group include a tertiary alkyl group. Examples of the alkoxy group (substituent) in the alkoxy-substituted methyl group include an alkoxy group having 1 to 4 carbon atoms. Moreover, as an alkyl group (substituent) in an alkylsulfanyl substituted methyl group, a C1-C4 alkyl group etc. are mentioned, for example. As carbon number of a tertiary alkyl group, 4-30 are preferable and 4-20 are more preferable. The tertiary alkyl group may be any of a chain hydrocarbon group, an alicyclic hydrocarbon group, an alicyclic structure, and the like.

  As said structural unit (I), the structural unit represented by following formula (3) is preferable. Since the [A] polymer has the above structural unit, a polar group can be easily generated by an acid, and the compatibility between the [A] polymer and the [B] acid generator can be increased.

In said formula (3), R < ⁹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ¹⁰ is a chain hydrocarbon group having 1 to 10 carbon atoms. R ¹¹ and R ¹² are each independently a chain hydrocarbon group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are combined with each other. An alicyclic structure having 3 to 20 ring carbon atoms and a carbon atom to be bonded is represented.

R ⁹ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of increasing the copolymerizability of the monomer that provides the structural unit.

Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by R ¹⁰ , R ¹¹ and R ¹² include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, i-pentyl group, sec-pentyl group, neo-pentyl group, tert-pentyl group, n-hexyl group, i-hexyl group, Examples thereof include alkyl groups such as n-heptyl group, i-heptyl group, n-octyl group, i-octyl group, n-nonyl group, i-nonyl group, n-decyl group and i-decyl group. Among these, the chain hydrocarbon group is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group, an ethyl group, or an i-propyl group, and even more preferably a methyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹¹ and R ¹² include monocyclic rings such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. And an alicyclic hydrocarbon group such as a norbornyl group, an isobornyl group, an adamantyl group, a tricyclodecanyl group, and a tetracyclododecanyl group. Among these, as the alicyclic hydrocarbon group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an isobornyl group, and an adamantyl group are preferable, and a cyclopentyl group and an adamantyl group are more preferable. The number of carbon atoms of the ^{R 11} and ^{R 12,} preferably 4 to 15, 4 to 12 is more preferable.

Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by the carbon atoms to which R ¹¹ and R ¹² are combined and bonded to each other include, for example, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cyclooctane structure, and the like. A cyclic alicyclic hydrocarbon group; a polycyclic alicyclic hydrocarbon group such as a norbornane structure and an adamantane structure. Among these, as the alicyclic structure, a cyclopentane structure, a cyclohexane structure, a norbornane structure, and an adamantane structure are preferable, and a cyclopentane structure and an adamantane structure are more preferable. The number of carbon atoms of the ^{R 11} and ^{R 12,} preferably 4 to 15, 4 to 12 is more preferable.

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

R < ⁹ > -R < ¹² > is synonymous with the said Formula (3) in said formula (4-1)-(4-4). R is an integer of 1 to 4.

  As a structural unit represented by the said Formula (3) or (4-1)-(4-4), the structural unit represented by a following formula etc. are mentioned, for example.

In the above formula, R ⁹ has the same meaning as the above formula (3).

  The structural unit (I) is preferably a structural unit represented by the above formula (4-1) or a structural unit represented by the formula (4-2), and is derived from 1-alkyl-1-cyclopentyl (meth) acrylate. The structural unit derived from 2-alkyl-2-adamantyl (meth) acrylate is more preferable. In addition, a structural unit derived from 1-methyl-1-cyclopentyl (meth) acrylate, a structural unit derived from 1-ethyl-1-cyclopentyl (meth) acrylate, and derived from 2-methyl-2-adamantyl (meth) acrylate A structural unit derived from a structural unit, 2-isopropyl-2-adamantyl (meth) acrylate, is more preferred. (Meth) acrylate refers to acrylate or methacrylate.

  As a content rate of structural unit (I), 20 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 40 mol%-70 mol% are more preferable. By setting the content ratio within the above range, a sufficient amount of acid tends to be dissociated in the photoresist composition. When the content ratio of the structural unit (I) is less than the lower limit, the pattern forming property of the photoresist composition may be deteriorated. When the content rate of structural unit (I) exceeds the said upper limit, the adhesiveness of the resist pattern formed may fall.

<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] The polymer further has the structural unit (II), whereby the solubility in the developer can be adjusted. Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved.

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

In the above formula, R ¹³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Among these, as R ¹³ , a methyl group is preferable.

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

  As a content rate of structural unit (II), 0 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-80 mol% are more preferable, 30 mol% More preferred is ˜70 mol%. By making the content rate of structural unit (II) into the said range, the solubility to the developing solution of a [A] polymer can be improved more. Moreover, the adhesiveness of the resist pattern formed from the said photoresist composition and a board | substrate can be improved more. When the content rate of structural unit (II) exceeds the said upper limit, the pattern formation property of the said photoresist composition may fall.

<Other structural units>
[A] The polymer may contain other structural units in addition to the structural units (I) and (II). Examples of other structural units include a structural unit containing a non-acid dissociable alicyclic hydrocarbon group, a structural unit having a polar group, and the like. As a content rate of another structural unit, it is 30 mol% or less normally with respect to all the structural units which comprise a [A] polymer, and 20 mol% or less is preferable.

  The content of the [A] polymer in the photoresist composition is usually 70% by mass or more and preferably 75% by mass or more with respect to the total solid content. [A] If the content of the polymer is less than the lower limit, the pattern forming property of the photoresist composition may be lowered. In addition, the said photoresist composition may contain 1 type (s) or 2 or more types of [A] polymers.

<[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.

  Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclohexane). Propyl radical initiators such as propylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroper And peroxide radical initiators such as oxide and cumene hydroperoxide. Among these, as the radical polymerization initiator, 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.

As the solvent used for the polymerization, for example,
alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, 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, 2-butanone, 2-pentanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. As the solvent, 2-butanone is preferable. The solvent used for these polymerizations may be used alone or in combination of two or more.

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

  [A] The polystyrene-reduced weight average molecular weight (Mw) by gel permeation chromatography (GPC) of the polymer is not particularly limited and is usually 1,000 or more and 500,000 or less, and 2,000 or more and 400,000. The following is preferable, and 3,000 to 300,000 is more preferable. [A] If the Mw of the polymer is less than the above 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 be lowered.

  [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. . When Mw / Mn exceeds the above upper limit, the heat resistance of the resulting resist film may be lowered.

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, manufactured by Tosoh)
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

  [A] The low molecular weight component contained in the polymer means a component having a molecular weight of 1,000 or less. The content (% by mass) of the low molecular weight component is preferably less than 0.5% by mass, more preferably less than 0.2% by mass, and 0.1% by mass from the viewpoint of increasing the glass transition temperature of the [A] polymer. Less than is more preferable.

The content (% by mass) of the low molecular weight component in the present specification is a value measured using high performance liquid chromatography (HPLC) under the following conditions.
HPLC column: Intersil ODS-25 μm, 4.6 mmφ × 250 mm (manufactured by GL Sciences Inc.)
Elution solvent: acrylonitrile / 0.1% by mass phosphoric acid aqueous solution Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractive index

<[B] Acid generator>
[B] The acid generator is an acid generator containing at least the compound (1). The acid generator refers to a compound that absorbs energy upon exposure and generates an acid such as sulfonic acid. [A] By using a photoresist composition containing a polymer and [B] an acid generator, it is possible to form a resist pattern excellent in pattern shape such as a cross-sectional shape and etching resistance while exhibiting excellent MEEF performance. . [B] The acid generator can contain a compound other than the compound (1) as long as the effects of the present invention are not impaired, and can also be used as an acid generator composition. These compounds may be used alone or in combination of two or more.

Although it is not necessarily clear why the photoresist composition has the above-described configuration, the following reason is presumed. That is, when R ² is the alkanediyl group or the fluorinated alkanediyl group, the compatibility of the [B] acid generator with the [A] polymer and the like can be increased, and [B] The acid generator can be more uniformly dispersed. As a result, the resist pattern is unlikely to have a top-loss shape unlike conventional ones, and the cross-sectional shape tends to be rectangular. Furthermore, by suitable polar sulfonic acid ester structure and the R ^2, since acid diffusion resistance is appropriately controlled, is believed possible to improve the MEEF performance of the photoresist composition. Furthermore, the number of fluorine atoms in R ² is relatively small, i.e. hydrofluoric primes the R ² in the above range, it is possible to improve the resistance to etching.

<Compound (1)>
Compound (1) is represented by the following formula (1).

In the above formula (1), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number. Q ⁺ is a monovalent photodegradable organic cation.

  The number of carbons refers to the number of carbons contained in the hydrocarbon group and does not include the number of carbons contained in any substituent. The number of ring atoms refers to the number of carbon atoms and heteroatoms contained in the heterocyclic group, and does not include the number of carbon atoms contained in any substituent.

The compound (1) contains an anion and a photodegradable organic cation (Q ⁺ ). A “photodegradable organic cation” is a cation containing a carbon atom that can decompose upon exposure to generate protons.

Since R ¹ is the hydrocarbon group or the heterocyclic group, excellent compatibility with the [A] polymer or the [E] solvent can be ensured. When the number of carbon atoms of the hydrocarbon group or the number of ring atoms of the heterocyclic group exceeds the upper limit, the compatibility is lowered.

Examples of the hydrocarbon group include:
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, i-pentyl group, sec-pentyl group , Neo-pentyl group, tert-pentyl group, n-hexyl group, i-hexyl group, n-heptyl group, i-heptyl group, n-octyl group, i-octyl group, n-nonyl group, i-nonyl group Alkyl groups such as n-decyl group and i-decyl group;
A monocyclic cycloalkyl group such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an isobornyl group, an adamantyl group, a tricyclodecanyl group, a tetracyclododecanyl group;
Alkenyl groups such as ethenyl group, 1-propen-1-yl group;
An alkynyl group such as an ethynyl group or a propynyl group;
Aryl groups such as phenyl group, naphthyl group, biphenyl group, fluorenyl group, anthryl group, phenanthryl group;
Examples thereof include aralkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group and 2-naphthylethyl group.

  As carbon number of a hydrocarbon group, 1-20 are preferable and 1-15 are more preferable.

Examples of the heterocyclic group include:
Furyl group, pyrrolyl group, thienyl group, oxazolyl group, isoxazolyl group, imidazolyl group, thiazolyl group, isothiazolyl group, pyridinyl group, pyrimidinyl group, tetrazolyl group, pyrazolyl group, pyridazinyl group, pyrazinyl group, thiadiazolyl group, dibenzofuranyl group, etc. An aromatic heterocyclic group (ie, a heteroaryl group);
Examples thereof include aliphatic heterocyclic groups such as piperidinyl group, tetrahydropyranyl group, tetrahydrofuranyl group, oxetanyl group, azetidinyl group, pyrrolidinyl group, morpholinyl group, thiomorpholinyl group, dioxanyl group, piperazinyl group and the like.

  As a ring atom number of a heterocyclic group, 3-20 are preferable and 3-15 are more preferable.

In the hydrocarbon group and heterocyclic group, a part or all of the hydrogen atoms may be substituted with an arbitrary substituent as long as the effects of the present invention are not impaired. The substituent is not particularly limited as long as desired physical properties can be obtained, and examples thereof include an alkoxy group, a hydroxy group, an aldehyde group, a carboxy group, a carbonyl group, an amide group, an imide group, an amino group, an imino group, and a cyano group. And known groups such as a group, an azo group, an azide group, a thiol group, a sulfo group, a nitro group, an ether group, an ester group, a group having a lactone structure, an alkylcarbonyl group, an oxo group, and a halogen atom. Of these, an oxo group is preferable as the substituent. That is, the R ¹ preferably contains a carbonyl group.

R ¹ is preferably a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aromatic heterocyclic group, and an unsubstituted alkyl group, a substituted cycloalkyl group, or an unsubstituted An aromatic heterocyclic group is more preferable, an unsubstituted alkyl group having 1 to 4 carbon atoms, a cycloalkyl group substituted with an oxo group, an aromatic heterocyclic group containing an oxygen atom as a constituent atom, a methyl group, An n-butyl group, a 10-camphor group, and a dibenzofuranyl group are particularly preferable.

R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number, preferably 2 carbon atoms having a fluorine number smaller than the carbon number. ~ 30 fluorinated alkanediyl groups. When the number of carbon atoms of the hydrocarbon group or the number of ring atoms of the heterocyclic group exceeds the above upper limit, solubility in a solvent decreases.

  Examples of the alkanediyl group include methanediyl group, ethanediyl group, propanediyl group, butanediyl group, pentanediyl group, hexanediyl group, heptanediyl group, octanediyl group, nonanediyl group, and decandiyl group.

  Examples of the fluorinated alkanediyl group include groups in which a part of hydrogen atoms of the alkanediyl group is substituted with fluorine atoms, and the number of fluorines is smaller than the number of carbons. By setting the number of fluorine within the above range, it is speculated that the [B] acid generator can have both excellent properties such as lipophilicity derived from a hydrocarbon moiety and polarity derived from a fluorine atom.

  As carbon number of the said alkanediyl group, 1-20 are preferable and 1-10 are more preferable. Moreover, as carbon number of the said fluorinated alkanediyl group, 2-20 are preferable and 2-10 are more preferable.

  The alkanediyl group and the fluorinated alkanediyl group may be linear or may have a side chain.

R ² is a fluorinated alkanediyl group, and the fluorinated alkanediyl group preferably has 2 or more fluorine atoms. In this case, the strength of the generated acid can be increased. As a result, according to the photoresist composition, it is possible to form a resist pattern that is superior in pattern shape and etching resistance while exhibiting better MEEF performance. .

  Examples of the fluorinated alkanediyl group having 2 or more fluorine atoms include any hydrogen atom such as a propanediyl group, a butanediyl group, a pentanediyl group, a hexanediyl group, a heptanediyl group, an octanediyl group, a nonanediyl group, and a decandiyl group. Examples thereof include those substituted by 2 or more atoms.

  As said fluorine number, 2-10 are more preferable, and 2-8 are more preferable. The fluorine number is smaller than the carbon number of the fluorinated alkanediyl group.

  The fluorinated alkanediyl group is preferably represented by the following formula (i).

In the above formula (i), R ³ is an alkanediyl group having 3 or more carbon atoms or a fluorinated alkanediyl group having 3 or more carbon atoms.

[B] By having the group represented by the above formula (i), the acid generator can further increase the strength of the generated acid, and as a result, the photoresist composition further enhances the above characteristics. Can do. Note that the —CF ₂ — group of the above formula (i) is bonded to the —SO ₃ ^— group of the above formula (1).

As R ³ , for example, one hydrogen atom is substituted with a fluorine atom or an unsubstituted propanediyl group, one or two hydrogen atoms are substituted with a fluorine atom, or unsubstituted butanediyl A group wherein 1 to 3 hydrogen atoms are substituted by fluorine atoms or unsubstituted pentanediyl group, 1 to 4 hydrogen atoms are substituted by fluorine atoms or unsubstituted hexanediyl group, 1 1 to 5 hydrogen atoms are substituted by fluorine atoms or unsubstituted heptanediyl groups, 1 to 6 hydrogen atoms are substituted by fluorine atoms or unsubstituted octanediyl groups, 1 to 7 Examples include a hydrogen atom substituted with a fluorine atom or an unsubstituted nonanediyl group, 1 to 8 hydrogen atoms substituted with a fluorine atom, or an unsubstituted decandiyl group. The In addition, any hydrogen atom may be substituted with a fluorine atom as long as the effects of the present invention are not impaired.

The number of carbon atoms of the R ^3, in any case alkanediyl group and a fluorinated alkanediyl group, preferably 3 to 29, more preferably from 3 to 19, more preferably 3 to 9. When the number of carbon atoms is within the above range, the compound (1) tends to exhibit better compatibility with the [A] polymer.

As R ³ , one hydrogen atom is substituted with a fluorine atom or an unsubstituted propanediyl group, one or two hydrogen atoms are substituted with a fluorine atom, or an unsubstituted butanediyl group, 1 to 3 hydrogen atoms are substituted by fluorine atoms or unsubstituted pentanediyl groups, 1 to 4 hydrogen atoms are substituted by fluorine atoms or unsubstituted hexanediyl groups, 1 to 5 hydrogen atoms are substituted by fluorine atoms or unsubstituted heptanediyl groups, 1 to 6 hydrogen atoms are substituted by fluorine atoms or unsubstituted octanediyl groups, propanediyl groups, A difluorobutanediyl group, a difluorooctanediyl group, and a hexafluorooctanediyl group are more preferable.

  Examples of the anion of the compound (1) include anions represented by the following formulas (5-1) to (5-14). These anions may be used alone or in combination of two or more.

  Examples of the anion of the compound (1) include the formulas (5-1), (5-4), (5-5), (5-6), (5-7), (5-8) and (5). −11) is preferred, and the anion represented by the formula (5-1) is more preferred.

The Q ⁺ is not particularly limited as long as it is a monovalent photodegradable organic cation, and examples thereof include known photodegradable organic cations.

  Examples of the photodegradable organic cation include a sulfonium ion, an iodonium ion, an imidazolium ion, a pyridinium ion, an ammonium ion, a pyrrolidinium ion, a phosphonium ion, and the photodecomposable organic cation includes a sulfonium. Ions and iodonium ions are preferred. When the photodegradable organic cation is either a sulfonium ion or an iodonium ion, the above properties such as MEEF performance of the photoresist composition tend to be enhanced. These photodegradable organic cations may be used alone or in combination of two or more.

The Q ⁺ is more preferably at least one selected from the group consisting of a sulfonium cation represented by the following formula (2-1) and an iodonium cation represented by the following formula (2-2). The sensitivity of the resist pattern can be increased.

In the above formula (2-1), R ⁴ , R ⁵ and R ⁶ each independently represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Or a ring structure in which any two or more of these groups are combined with each other and the sulfur atom to which they are attached.

In the above formula (2-2), R ⁷ and R ⁸ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Or a ring structure in which these groups are combined together with an iodine atom to which they are bonded.

  The number of carbons refers to the number of carbons contained in each functional group, and does not include the number of carbons contained in any substituent.

  When the number of carbon atoms of the alkyl group or aryl group exceeds the upper limit, the compatibility of the compound with the [A] polymer and the solubility in the [E] solvent may be reduced.

As an arbitrary substituent which said R < ⁴ > -R < ⁸ > may have, the well-known functional group which was illustrated in R < ¹ > is mentioned, for example.

Examples of the alkyl group contained in R ⁴ , R ⁵ and R ⁶ include those exemplified for R ¹ . As carbon number of the said alkyl group, 1-15 are preferable and 1-10 are more preferable.

Examples of the aryl group contained in R ⁴ , R ⁵ and R ⁶ include those exemplified for R ¹ . Of these, the aryl group is preferably a phenyl group. As carbon number of the said aryl group, 6-25 are preferable and 6-20 are more preferable.

R ⁴ , R ⁵ and R ⁶ may represent a ring structure in which any two or more of these groups are combined with each other and the sulfur atom to which they are bonded. Examples of the ring structure include a structure in which one carbon atom in the alicyclic structure is substituted with a sulfur atom. As the number of ring atoms, 3 to 20 is preferable, and 3 to 15 is more preferable. If the number of return atoms is within the above range, the sensitivity of the resist pattern tends to be increased.

  Examples of the sulfonium cation include triphenylsulfonium cation, cyclohexyl 2-oxocyclohexylmethylsulfonium cation, dicyclohexyl 2-oxocyclohexylsulfonium cation, 2-oxocyclohexyldimethylsulfonium cation, 4-hydroxy-1-naphthyldimethylsulfonium cation, and diphenyl. Well-known cations such as -4-hydroxyphenylsulfonium cation and 4-t-butoxyphenyldiphenylsulfonium cation may be mentioned. Among these, the triphenylsulfonium cation is preferable as the sulfonium cation.

Examples of the alkyl group contained in R ⁷ and R ⁸ include those exemplified for R ¹ . As carbon number of the said alkyl group, 1-15 are preferable and 1-10 are more preferable.

Examples of the aryl group contained in R ⁷ and R ⁸ include those exemplified for R ¹ . Of these, the aryl group is preferably a phenyl group. As carbon number of the said aryl group, 6-25 are preferable and 6-20 are more preferable.

R ⁷ and R ⁸ may represent a ring structure in which these groups are combined with each other and an iodine atom to which they are bonded. Examples of the ring structure include a structure in which one carbon atom in the alicyclic structure is substituted with an iodine atom. As the number of ring atoms, 3 to 20 is preferable, and 3 to 15 is more preferable. If the number of return atoms is within the above range, the sensitivity of the resist pattern tends to be increased.

  Examples of the iodonium cation include known cations such as diphenyliodonium cation, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, and bis (4-t-butylphenyl) iodonium. Among these, a diphenyliodonium cation is preferable as the iodonium cation.

  As said compound (1), the combination of the above-mentioned anion and a photodegradable organic cation etc. are mentioned, for example.

  As said compound (1), the compound represented by a following formula is preferable.

  [B] The content of the compound (1) contained in the acid generator is not particularly limited and is usually 10% by mass or more and preferably 20% by mass or more and 100% or less. If the content is less than the above lower limit, the cross-sectional shape of the resist pattern may be lowered.

  [B] Other acid generators other than the compound (1) contained in the acid generator include, for example, onium salt compounds other than the compound (1), halogen-containing compounds, diazoketone compounds, sulfone compounds, sulfonic acid compounds, Examples thereof include diazomethane compounds, nitrobenzyl sulfonate compounds, imino sulfonate compounds, and the like.

Examples of the onium salt compound include iodonium salts and sulfonium salts other than the compound (1), and phosphonium salts, diazonium salts, pyridinium salts, and the like.
Specifically, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1 , 1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t- Butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfur Sulfonate, cyclohexyl 2-oxo-cyclohexyl methyl sulfonium trifluoromethanesulfonate, dicyclohexyl 2-oxo-cyclohexyl trifluoromethane sulfonate, and 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethane sulfonates.

  Examples of the halogen-containing compound include haloalkyl group-containing hydrocarbon compounds and haloalkyl group-containing heterocyclic compounds. Specifically, (trichloromethyl)-such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine, etc. s-triazine derivatives; 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane and the like.

  Examples of the diazoketone compound include 1,3-diketo-2-diazo compounds, diazobenzoquinone compounds, diazonaphthoquinone compounds, and the like. Specifically, for example, 1,2-naphthoquinonediazide of 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonylchloride, 2,3,4,4′-tetrahydroxybenzophenone -4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,1,1-naphthoquinonediazide-4-sulfonic acid ester of 1,1,1-tris (4-hydroxyphenyl) ethane, 1, Examples include 2-naphthoquinonediazide-5-sulfonic acid ester.

  Examples of the sulfone compound include β-ketosulfone, β-sulfonylsulfone, and α-diazo compounds of these compounds. Specific examples include 4-trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl) methane, and the like.

  Examples of the sulfonic acid compounds include alkyl sulfonic acid esters, alkyl sulfonic acid imides, haloalkyl sulfonic acid esters, aryl sulfonic acid esters, and imino sulfonates.

  Specifically, benzoin tosylate, pyrogallol tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2.2.1] hept-5-ene- 2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2.1] hept -5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonylbicyclo [2.2.1] hept- 5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonyloxy) succinimide N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1, 2,2-tetrafluoroethanesulfonyloxy) succinimide, 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate, 1,8-naphthalenedicarboxylic acid imidononafluoro-n-butanesulfonate, 1,8-naphthalenedicarboxylic acid imide perfluoro -N-octane sulfonate etc. are mentioned.

  These compounds may be used alone or in combination of two or more. [B] As a compounding quantity of an acid generator, it is 0.1-20 mass parts normally with respect to 100 mass parts of [A] polymers, and 0.5-15 mass parts is preferable. When the blending amount is within the above range, excellent compatibility between the [A] polymer and the [B] acid generator tends to be ensured. If the blending amount exceeds the above upper limit, the transparency of the photoresist composition with respect to exposure light may be reduced, and it may be difficult to obtain a resist pattern having the desired characteristics. When the blending amount is less than the above lower limit, the sensitivity and developability of the photoresist composition may be lowered.

<Method for producing acid generator>
The acid generator containing the compound (1) is not particularly limited and can be produced according to a known method.

As an example of the process for the preparation of compounds (1), ^Br-R 2 -OH as the starting material ^{(R 2} is as defined in the above formula (1).) The compound obtained using the
Heating the starting material in an aqueous acetonitrile solution in the presence of sodium dithionite and sodium bicarbonate;
Heating the aqueous layer obtained in the previous step in the presence of aqueous hydrogen peroxide and disodium tungstate;
To the aqueous layer obtained in the previous step, a photodegradable organic cation (Q ⁺ ) chloride (Q ⁺ is as defined in the above formula (1)), dichloromethane and water are added and stirred at room temperature. Triethylamine and 4-dimethylaminopyridine were added to the step and the dichloromethane solution obtained in the previous step, cooled, and then R ¹ —SO ₂ Cl (R ¹ is as defined in the above formula (1).) It can obtain by the manufacturing method which has the process of dripping and stirring the dichloromethane solution. Other process conditions such as temperature, pressure, time and equipment in each process are not particularly limited, and are appropriately set according to the raw materials used. The number of steps in each step is not particularly limited, and may be performed in one step or in multiple steps.

<Optional component>
The photoresist composition may contain a [C] acid diffusion controller, a [D] fluorine atom-containing polymer and a [E] solvent as suitable components, and within a range not impairing the effects of the present invention. , [F] uneven distribution accelerator, surfactant, alicyclic skeleton compound, sensitizer, crosslinking agent, surfactant, dissolution inhibitor, plasticizer, stabilizer, colorant, antihalation agent, dye, pigment , Adhesion assistant, alkali-soluble resin, low-molecular alkali solubility controller with acid-dissociable protecting group, basic compound, dissolution inhibitor, storage stabilizer, antifoaming agent and other optional components be able to. The blending amount of other components can be appropriately determined according to the purpose. These components are described below.

<[C] Acid diffusion controller>
[C] The acid diffusion controller controls the diffusion phenomenon of the acid generated by exposure in the resist film, and suppresses an undesirable chemical reaction in the non-exposed region, and the storage stability of the resulting photoresist composition In addition to further improving the resolution as a resist, it is also possible to suppress changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing. A thing is obtained. [C] As a form of inclusion in the photoresist composition of the acid diffusion controller, a form of a free compound (hereinafter referred to as “[C] acid diffusion controller” as appropriate) was incorporated as a part of the polymer. It may be in the form or both forms.

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

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′— Tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis ( 4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4- Aminophenyl) -2- (4-hydroxyphenyl) propane, 1 4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) Ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

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

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea. Etc.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, 4 -Methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2. 2] Octane, Nt-butoxycarbonyl 4-hydroxypiperidine and the like.

  [C] Among these, Nt-butoxycarbonyl 4-hydroxypiperidine is preferable as the acid diffusion controller.

  These [C] acid diffusion controllers may be used alone or in combination of two or more. The content of [C] acid diffusion controller is preferably less than 15 parts by mass with respect to 100 parts by mass of [A] polymer when [C] acid diffusion controller is [C] acid diffusion controller. Less than 10 mass parts is more preferable. [C] When the content of the acid diffusion controller is more than the above, the sensitivity as a resist tends to decrease.

<[D] Fluorine atom-containing polymer>
The photoresist composition may further contain a polymer having a higher fluorine atom content than the [A] polymer (hereinafter also referred to as “[D] fluorine atom-containing polymer”). When the photoresist composition contains a [D] fluorine atom-containing polymer, the hydrophobicity of the resist film is improved, and even when immersion exposure is performed, the substance elution suppression is excellent, and the resist film and the liquid Since the receding contact angle with the immersion liquid can be made sufficiently high, and there are effects such as no water droplets remaining when scanning exposure is performed at high speed, the usefulness of the photoresist composition for immersion exposure is enhanced.

[D] The embodiment of the fluorine atom-containing polymer is not particularly limited as long as it has a fluorine atom.
A structure in which a fluorinated alkyl group is bonded to the main chain;
Structure in which a fluorinated alkyl group is bonded to the side chain;
Examples include a structure in which a fluorinated alkyl group is bonded to the main chain and the side chain.

  Examples of the monomer that gives a structure in which a fluorinated alkyl group is bonded to the main chain include, for example, α-trifluoromethyl acrylate compound, β-trifluoromethyl acrylate compound, α, β-trifluoromethyl acrylate compound, one or more types And compounds in which the hydrogen atom of the vinyl moiety is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

  Examples of the monomer that gives a structure in which a fluorinated alkyl group is bonded to the side chain include, for example, those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorinated alkyl group or a derivative thereof, acrylic acid or methacrylic acid And a compound in which the side chain is a fluorinated alkyl group or an ester compound thereof, and the side chain of one or more olefins (site not including a double bond) is a fluorinated alkyl group or a derivative group thereof.

  Monomers that give a structure in which a fluorinated alkyl group is bonded to the main chain and side chain include, for example, α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid. Fluorinated alkyl group or its derivative group ester compound, etc., one or more vinyl moiety hydrogen atom substituted with fluorinated alkyl group such as trifluoromethyl group side chain fluorinated alkyl group Or substituted with a derivative thereof, a hydrogen atom bonded to a double bond of one or more alicyclic olefin compounds is replaced with a fluorinated alkyl group such as a trifluoromethyl group, and the side chain is fluorinated Examples thereof include alkyl groups and derivatives thereof. In addition, an alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  As said structure, the structural unit represented by a following formula is preferable.

In the above formula, R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, a fluorine atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have at least one fluorine atom.

  In addition, [D] a fluorine atom-containing polymer is a structural unit other than the fluorine-containing structural unit as long as the effects of the present invention are not impaired, a structural unit having an acid dissociable group, a lactone structure, a cyclic carbonate structure, and a sultone structure You may have a structural unit which has at least 1 sort (s) chosen from the group which consists of. Examples of such a structural unit include those exemplified in the structural units (I) and (II) in the [A] polymer.

  [D] The fluorine atom-containing polymer is preferably a copolymer containing a fluorine-containing structural unit and a structural unit containing an acid dissociable group.

  [D] In the fluorine atom-containing polymer, the content ratio of the fluorine-containing structural unit is preferably 5 mol% to 100 mol% with respect to all the structural units constituting the [D] fluorine atom-containing polymer. % To 80 mol% is more preferable, and 20 mol% to 70 mol% is more preferable. If the content ratio exceeds the above upper limit, pattern collapse or pattern peeling may occur. If the content ratio is less than the above lower limit, the substance elution inhibiting property may be lowered. [D] The polymer may be a random copolymer or a block copolymer.

[D] In the fluorine atom-containing polymer, the fluorine atom content is preferably 1% by mass to 60% by mass, and more preferably 2% by mass to 25% by mass. When the fluorine atom content exceeds the above upper limit, the pattern of the formed resist pattern may fall or peel off. If the fluorine atom content is less than the above lower limit, the substance elution suppression property may be lowered. The fluorine atom content in the polymer can be calculated from the structure of the polymer by ¹³ C-NMR.

  These [D] fluorine atom-containing polymers may be used alone or in combination of two or more. [D] The content of the fluorine atom-containing polymer is preferably less than 15 parts by mass and more preferably less than 10 parts by mass with respect to 100 parts by mass of the polymer [A]. [D] If the content of the fluorine atom-containing polymer is above, desired resist characteristics may not be obtained.

  As in the case of the [A] polymer, the [D] fluorine atom-containing polymer is prepared by, for example, using a radical polymerization initiator and a monomer corresponding to each predetermined structural unit in an appropriate solvent. It can be synthesized by polymerization.

<[E] solvent>
The photoresist composition usually contains an [E] solvent. The [E] solvent used is not particularly limited as long as it is a solvent capable of dissolving at least the [A] polymer and the [B] acid generator. Examples of such solvents include alcohols, ethers, diethylene glycol alkyl ethers, ethylene glycol alkyl ether acetates, propylene glycol monoalkyl ethers, propylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ether propionate. , Aromatic hydrocarbons, ketones, esters, amides, nitriles, and mixed solvents thereof can be used.

As said [E] solvent,
Examples of alcohols include benzyl alcohol and diacetone alcohol;
Examples of ethers include dialkyl ethers such as tetrahydrofuran, diisopropyl ether, di n-butyl ether, di n-pentyl ether, diisopentyl ether, and di n-hexyl ether;
Examples of diethylene glycol alkyl ethers include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol ethyl methyl ether;
Examples of ethylene glycol alkyl ether acetates include methyl cellosolve acetate, ethyl cellosolve acetate, ethylene glycol monobutyl ether acetate, and ethylene glycol monoethyl ether acetate;
Examples of propylene glycol monoalkyl ethers include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether;
Examples of propylene glycol monoalkyl ether acetates include propylene glycol monomethyl ether acetate (propylene glycol monomethyl ether acetate), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate; Examples of propionates include propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether propionate, propylene glycol monopropyl ether propionate, propylene glycol monobutyl ether propionate and the like;
Examples of aromatic hydrocarbons include toluene and xylene;
Examples of ketones include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone, 4-hydroxy-4-methyl-2-pentanone, and the like;
Examples of esters include methyl acetate, ethyl acetate, propyl acetate, i-propyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, 2-hydroxy-2-methylpropionic acid Ethyl, methyl hydroxyacetate, ethyl hydroxyacetate, butyl hydroxyacetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, protyl 3-hydroxypropionate, 3-hydroxy Butyl propionate, methyl 2-hydroxy-3-methylbutanoate, methyl methoxyacetate, ethyl methoxyacetate, propyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, propyl ethoxyacetate, ethoxy Butyl acetate, methyl propoxyacetate, ethyl propoxyacetate, propylpropoxyacetate, butyl propoxyacetate, methyl butoxyacetate, ethyl butoxyacetate, propylbutoxyacetate, butylbutoxyacetate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, 2 -Propyl methoxypropionate, butyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate and the like;
Examples of amides include formamide, N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like;
Examples of nitriles include acetonitrile and propionitrile.

  Among these, as the above-mentioned [E] solvent, propylene glycol monoalkyl ether acetates and ketones are preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are more preferable.

  These [E] solvents may be used alone or in combination of two or more. [E] The content of the solvent is preferably 500 parts by weight to 8,000 parts by weight, and more preferably 600 parts by weight to 7,000 parts by weight with respect to 100 parts by weight of the polymer [A]. If the content exceeds the above upper limit, the production cost may increase. When the content is less than the above lower limit, the [A] polymer or the like may not be sufficiently dissolved.

<[F] Localization promoter>
The said photoresist composition can contain the [F] uneven distribution promoter which has the effect of segregating the said [D] fluorine atom containing polymer to the resist film surface more efficiently. By adding the additive to the photoresist composition, the amount of the fluorine atom-containing polymer added can be reduced as compared with the conventional case. Therefore, while maintaining the basic resist characteristics such as MEEF performance, LWR performance, and pattern collapse resistance, further elution of components from the resist film to the immersion liquid is performed, and immersion exposure is performed at a higher speed by high-speed scanning. Examples of such additives include lactone compounds such as γ-butyrolactone, cyclic carbonate compounds such as propylene carbonate, nitrile compounds such as succinonitrile, polyhydric alcohols such as glycerin, and the like. Among these, γ-butyrolactone is preferable as the additive.

  These [F] uneven distribution promoters may be used alone or in combination of two or more. [F] The content of the uneven distribution accelerator is preferably 1 part by mass to 100 parts by mass and more preferably 2 parts by mass to 80 parts by mass with respect to 100 parts by mass of the polymer [A]. If the content exceeds the above upper limit, the production cost may increase. When the content is less than the above lower limit, [D] a fluorine atom-containing polymer may be required in many cases.

<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 In addition to nonionic surfactants such as distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F173 (above, manufactured by DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, manufactured by Asahi Glass), etc. It is done. These surfactants may be used alone or in combination of two or more.

<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, 1-adamantanecarboxylate t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. These alicyclic skeleton containing compounds may be used independently and may use 2 or more types together.

<Sensitizer>
The sensitizer exhibits the effect of increasing the amount of acid generated from the [B] acid generator, and has the effect of improving the “apparent sensitivity” of the photoresist 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 independently and may use 2 or more types together.

<Method for preparing photoresist composition>
The preparation method of a photoresist composition is not specifically limited, It can carry out according to a well-known method. The photoresist composition can be prepared, for example, by mixing [A] polymer, [B] acid generator and an optional component in a predetermined ratio in an organic solvent. The photoresist composition can be prepared and used in a state dissolved or dispersed in a suitable organic solvent.

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

  According to the resist pattern forming method, since the photoresist composition described above is used, it is possible to form a resist pattern that is excellent in cross-sectional rectangularity and etching resistance while exhibiting excellent MEEF performance. . Hereinafter, each step will be described.

[Resist film forming step]
In the resist film forming step, a resist film is formed using the photoresist composition. Examples of the substrate on which the resist film is formed include a silicon wafer, silicon dioxide, a wafer coated with an antireflection film, and the like. Examples of the method for applying the photoresist composition include methods such as spin coating, cast coating, and roll coating. It is preferable to evaporate and remove the solvent in the coating film by pre-baking (PB) the coating film formed by the above application. As PB temperature, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[Exposure process]
In the exposure step, the resist film formed in the resist film formation step is exposed. This exposure is performed by irradiating exposure light through a photomask or the like (in some cases through an immersion medium such as water). Examples of exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme 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. Can be mentioned. Of these, far ultraviolet rays, extreme ultraviolet rays, and electron beams are preferable as exposure light, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (13.5 nm), and electron beam are preferable. More preferred are ArF excimer laser light and electron beam.

  After the above exposure, post-exposure baking (PEB) is performed to promote the dissociation of the acid-dissociable group of the [A] polymer by the acid generated from the [B] acid generator by exposure in the exposed portion of the resist film. It is preferable to make it. This PEB can surely cause a difference in solubility in the developer between the exposed portion (exposed portion) and the unexposed portion (unexposed portion). As PEB temperature, it is 50 to 180 degreeC normally, and 80 to 130 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

  When performing immersion exposure, a protective film for immersion that is insoluble in immersion liquid may be provided on the resist film before the exposure process in order to protect the direct contact between the immersion liquid and the resist film. Good. As the protective film for immersion, a solvent-removable protective film that peels off with a solvent before the developing step (see, for example, JP-A-2006-227632), a developer-removable protective film that peels simultaneously with development in the developing step ( For example, any of International Publication No. 2005/069076, International Publication No. 2006/035790, etc.) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

[Development process]
In the development process, the resist film exposed in the exposure process is developed. Thereby, a predetermined resist pattern is formed. The development method may be alkali development or organic solvent development. Usually, a positive resist pattern is formed by alkali development, and a negative resist pattern is formed by organic solvent development. After the development, it is common to wash with water or a rinse solution such as alcohol and dry.

  As the developer, in the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propyl Amine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1, An alkaline aqueous solution in which at least one alkaline compound such as 5-diazabicyclo- [4.3.0] -5-nonene is dissolved can be used. Among these, as the developer, a TMAH aqueous solution is preferable, and a 2.38% by 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, solvents containing organic solvents, and the like can be given. Examples of the organic solvent include one or more of the solvents listed as the [E] solvent of the above-described photoresist composition. Among these, an ester solvent and a ketone solvent are preferable as the organic solvent. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable.

  The photoresist composition of the present invention is useful as a chemically amplified resist. In a chemically amplified resist, an acid-dissociable group such as the [A] polymer is dissociated by the action of an acid generated by exposure to generate a polar group typified by a carboxy group. As a result, the solubility of the exposed portion of the resist in the alkaline developer is increased, and the exposed portion is dissolved and removed by the alkaline developer to obtain a positive resist pattern. In addition, by using a relatively low-polarity developer containing an organic solvent or the like as a developing solution, a negative resist pattern can be obtained by making the polar group portion generated by the exposure hardly soluble in the developing solution. .

  Since the said photoresist composition is excellent in compatibility, the resist pattern obtained from the said photoresist composition can have the said characteristic that was excellent. Specifically, it is possible to form a resist pattern that exhibits MEEF performance of preferably 4.7 or less, more preferably 4.4 or less, has a good pattern shape, and excellent etching resistance.

  According to the photoresist composition, resist pattern forming method, and acid generator of the present invention, a resist pattern having excellent cross-sectional rectangularity and etching resistance can be formed while exhibiting excellent MEEF performance. 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.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[ ¹ H-NMR and ¹³ C-NMR analysis]
Analysis was performed using JNM-EX400 manufactured by JEOL Ltd. and deuterated chloroform as a measurement solvent.

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

[Content of low molecular weight components]
The content (% by mass) of the low molecular weight component is a value measured using high performance liquid chromatography (HPLC) under the following conditions.
HPLC column: Intersil ODS-25 μm, 4.6 mmφ × 250 mm (manufactured by GL Sciences Inc.)
Elution solvent: acrylonitrile / 0.1% by mass phosphoric acid aqueous solution Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractive index

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (B-1))

Compound (1) 55.0 g (230 mmol) was dissolved in 100 g of acetonitrile aqueous solution in which 60.1 g (345 mmol) of sodium dithionite and 32.8 g (391 mmol) of sodium bicarbonate were dissolved (mass ratio of acetonitrile: water 4: 3). ), Heated to 65 ° C. and stirred for 7 hours. The reaction solution was separated and purified, and the aqueous layer was recovered.
To the obtained aqueous layer was added 100 g of acetonitrile, 29.2 g of an aqueous solution containing hydrogen peroxide of 9.79 g (288 mmol) of 31% by mass hydrogen peroxide, and 7.59 g (23 mmol) of disodium tungstate, up to 40 ° C. Heat and stir for 8 hours. The reaction solution was separated and purified, and the aqueous layer was recovered.
To this aqueous layer (solid content: 36.2 g; 138 mmol), 41.2 g (138 mmol) of triphenylsulfonium chloride, 120 g of dichloromethane and 60 g of water were added and stirred at room temperature for 2 hours. The reaction solution was separated and purified, and the organic layer was collected and concentrated to obtain 62.3 g of the compound (2).
To a solution of 62.3 g (124 mmol) of the obtained compound (2) in 310 g of dichloromethane, 18.8 g (186 mmol) of triethylamine and 0.303 g (2.48 mmol) of 4-dimethylaminopyridine were added and cooled to 0 ° C. did. Subsequently, 30 mL of a dichloromethane solution of 37.4 g (149 mmol) of D-camphor-10-sulfonyl chloride was added dropwise and stirred for 6 hours. Subsequently, separation and purification were performed using dichloromethane and water to obtain a compound (B-1) (yield 79.1 g, total yield 48%).

[Physical properties of compound (B-1)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.26-4.36 (m, 2H), 3. 58 (d, 1H), 3.00 (d, 1H), 2.34-2.48 (m, 4H), 1.93-2.12 (m, 5H), 1.65 to 1.69 ( m, 1H), 1.41-1.48 (m, 1H), 1.10 (s, 3H), 0.87 (s, 3H).

[Synthesis Examples 2 to 7] (Synthesis of Compounds (B-2) to (B-7))
By operating in the same manner as in Synthesis Example 1, compounds represented by the following formulas (B-2) to (B-7) were obtained.

[Physical properties of compound (B-2)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.26-4.36 (m, 2H), 3. 01 (s, 3H), 2.43-2.56 (m, 2H), 2.04-2.11 (m, 2H).

[Physical properties of compound (B-3)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.23-4.27 (m, 2H), 3. 07-3.11 (m, 2H), 2.41-2.56 (m, 2H), 2.03-2.11 (m, 2H), 1.79-1.87 (m, 2H), 1.42-1.51 (m, 2H), 0.95 (t, 3H).

[Physical properties of compound (B-4)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 8.97 (s, 1H), 8.47 (d, 1H), 8.06 (d, 1H), 7 .98 (d, 1H), 7.69-7.82 (m, 18H), 4.26-4.36 (m, 2H), 2.43-2.56 (m, 2H), 2.04 -2.11 (m, 2H).

[Physical properties of compound (B-5)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.26-4.36 (m, 2H), 3. 58 (d, 1H), 3.00 (d, 1H), 2.34-2.48 (m, 4H), 1.93-2.12 (m, 3H), 1.65 to 1.69 ( m, 5H), 1.41-1.48 (m, 7H), 1.10 (s, 3H), 0.87 (s, 3H).

[Physical properties of compound (B-6)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.26-4.36 (m, 2H), 3. 58 (d, 1H), 3.00 (d, 1H), 2.34-2.48 (m, 4H), 1.93-2.12 (m, 3H), 1.65 to 1.69 ( m, 5H), 1.41-1.48 (m, 3H), 1.10 (s, 3H), 0.87 (s, 3H).

[Physical properties of compound (B-7)]
¹ H-NMR analysis (measuring solvent: deuterated chloroform, reference material: tetramethylsilane); δ = 7.69-7.78 (m, 15H), 4.26-4.36 (m, 2H), 3. 58 (d, 1H), 3.00 (d, 1H), 2.74-2.88 (m, 4H), 1.93-2.12 (m, 5H), 1.65 to 1.69 ( m, 1H), 1.41-1.48 (m, 1H), 1.10 (s, 3H), 0.87 (s, 3H).

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

[Polymerization Example 1] (Synthesis of polymer (A-1))
80 g of 2-butanone was obtained from 21.12 g (55 mol%) of the compound (M-1), 3.84 g (10 mol%) of the compound (M-3) and 13.44 g (35 mol%) of the compound (M-5). A monomer solution was prepared by 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 solution was cooled with water and cooled to 30 ° C. or lower. The cooled polymerization solution 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).
Mw of (A-1) was 4,500, and Mw / Mn was 1.4. The content of the low molecular weight component (A-1) was 0.04% by mass. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-3) and (M-5) was 54 mol%, 11 mol% and 35 mol%, respectively. It was.

[Polymerization Example 2] (Synthesis of polymer (A-2))
Except having used the monomer of the kind and usage-amount shown in following Table 1, it operated similarly to the polymerization example 1, and synthesize | combined (A-2) used as a [A] polymer. The total mass of the monomers was the same as in Polymerization Example 1. Table 1 shows the contents of low molecular weight components, Mw, and (Mw / Mn) of each polymer obtained.

<[D] Synthesis of fluorine atom-containing polymer>
[Polymerization Example 3] (Synthesis of Fluorine Atom-Containing 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 a monomer solution charged with 3 g of AIBN was 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 solution was cooled with water to 30 ° C. or less, and poured into a solution of 600 g of methanol: water = 8: 2 (mass ratio) to precipitate a 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 fluorine atom-containing polymer (D-1). Mw of (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 photoresist composition>
The [B] acid generator, [C] acid diffusion controller, [E] solvent, and [F] uneven distribution accelerator used in the preparation of the photoresist composition are shown below.

[[B] acid generator]

[[C] acid diffusion controller]

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

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

[Example 1]
[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) 7 parts by weight (D-1) as a fluorine atom-containing polymer, (E-1) 2,590 parts by weight and (E-2) 1,110 parts by weight as a solvent [E], In addition, 15 parts by mass of (F-1) as a [F] uneven distribution accelerator was mixed, and the obtained mixed solution was filtered with a filter having a pore size of 0.20 μm to prepare a photoresist composition.

[Examples 2 to 14 and Comparative Examples 1 to 10]
Each photoresist composition was prepared in the same manner as in Example 1 except that the components of the types and amounts shown in Table 2 were used.

<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). On this antireflection film, a resist film having a thickness of 95 nm was formed using each of the prepared photoresist compositions, and SB was performed at 115 ° C. for 45 seconds. Next, this resist film is used for forming a 50 nm line and a 100 nm pitch using an ArF excimer laser light immersion exposure apparatus (NSR S610C, manufactured by NIKON) under the conditions of NA = 1.3, ratio = 0.800, Annular. Exposure was through a 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 50 nm is defined as an optimum exposure amount through a one-to-one line and space mask with a target dimension of 50 nm. did. The length of the resist pattern was measured using a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies).

<Evaluation>
About each prepared said photoresist composition, the sensitivity, MEEF performance, the squareness of cross-sectional shape, and etching resistance were evaluated in accordance with the following method. The evaluation results are shown in Table 3.

[sensitivity]
The optimum exposure amount was defined as sensitivity. At this time, when the sensitivity is 50 mJ / cm ² or less, the sensitivity can be evaluated as “good”, and when it exceeds 50 mJ / cm ² , it can be evaluated as “bad”.

[MEEF performance]
Using a scanning electron microscope (CG4000, manufactured by Hitachi High-Technologies Corp.), at the above optimal exposure amount, five types of mask sizes (48.0 nmLine / 100 nmPitch, 49.0 nmLine / 100 nmPitch, 50.0 nmLine / 100 nmPitch, 51.0 nmLine / 100 nmPitch) The resist pattern dimension resolved at 52.0 nm Line / 100 nm Pitch) was measured. Using the measured values, the horizontal axis represents the mask size, and the vertical axis represents the line width formed with each mask size. 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 “good” and when it exceeds 4.7, it can be evaluated as “bad”.

[Rectangularity of cross-sectional shape]
Using the scanning electron microscope, the resist pattern was observed, and the line width x above the pattern and the line width y below the pattern were measured at a total of 10 points. Each ratio x / y was calculated and the arithmetic mean value of these was obtained. If this value (x / y) is in the range of 0.9 ≦ (x / y) ≦ 1.1, the rectangular shape of the cross-sectional shape is “good” and (x / y) <0.9 or 1 .1 <(x / y), it can be evaluated as “bad”.

[Etching resistance]
Onishi parameters, which are generally known to be able to evaluate etching resistance, were calculated for the portion surrounded by the solid line in the following equation. As this value is a positive value and smaller, the etching resistance is “good”, and as this value is larger, it can be evaluated as “bad”.

Onishi parameter = (total number of atoms in the following part) / {(number of carbon atoms in the following part) − (number of oxygen atoms in the following part) − (number of fluorine atoms in the following part)}

Onishi parameters of the compounds according to the examples are 15.00 for the compounds (B-1) to (B-4), 5.40 for the compound (B-5), and 27.00 for the compound (B-6). In (B-7), it was 6.00. On the other hand, the Onishi parameter of the compound which concerns on a comparative example was -9.00 in compound (CB-1)-(CB-4). The Compounds (CB-5), -SO ₃ in the anion portion ^- was calculated Ohnishi parameter for the part bonded to was -2.60. This is due to the fact that the number of fluorine in the portion is larger than the number of carbon.

  As is clear from the results in Table 3 and the like, according to the photoresist composition of the example, the MEEF is small and the pattern shape and the etching resistance are both good. According to the photoresist composition of the comparative example, the MEEF The pattern shape and etching resistance were both poor.

  According to the photoresist composition and the resist pattern forming method of the present invention, it is possible to form a resist pattern that is excellent in cross-sectional rectangularity and etching resistance while exhibiting excellent MEEF performance. The acid generator of the present invention can be suitably used as a component of the photoresist composition. 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 (7)

The photoresist composition containing the acid generator containing the polymer which has a structural unit containing an acid dissociable group, and the compound represented by following formula (1).

(In Formula (1), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number, Q ⁺ is a monovalent photodegradable organic cation. .) The photoresist composition according to claim 1, wherein R ^{2 in the} formula (1) is the fluorinated alkanediyl group, and the fluorinated alkanediyl group has 2 or more fluorine atoms. The photoresist composition according to claim 2, wherein the fluorinated alkanediyl group is represented by the following formula (i).

(In formula (i), R ³ is an alkanediyl group having 3 or more carbon atoms or a fluorinated alkanediyl group having 3 or more carbon atoms.) Q ⁺ in the formula (1) is at least one selected from the group consisting of a sulfonium cation represented by the following formula (2-1) and an iodonium cation represented by the following formula (2-2). The photoresist composition according to 1.

(In formula (2-1), R ⁴ , R ⁵ and R ⁶ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Or a ring structure in which any two or more of these groups are combined with each other and the sulfur atom to which they are attached.
In Formula (2-2), are R ⁷ and R ⁸ each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms? Or a ring structure in which these groups are combined with each other and combined with an iodine atom to which they are bonded. ) The photoresist composition according to claim 1, wherein the structural unit is represented by the following formula (3).

(In Formula (3), R ⁹ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ¹⁰ is a chain hydrocarbon group having 1 to 10 carbon atoms. R ¹¹ and R ^12. Are each independently a chain hydrocarbon group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or together with the carbon atoms to which these groups are combined and bonded to each other It represents an alicyclic structure having 3 to 20 ring carbon atoms.) 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 photoresist composition according to claim 1. The acid generator containing the compound represented by following formula (1).

(In Formula (1), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or a substituted or unsubstituted monovalent heterocyclic group having 3 to 30 ring atoms. R ² is an alkanediyl group having 1 to 30 carbon atoms or a fluorinated alkanediyl group having 2 to 30 carbon atoms whose fluorine number is smaller than the carbon number, Q ⁺ is a monovalent photodegradable organic cation. .)