JP6079217B2 - Photoresist composition, resist pattern forming method, and acid generator - Google Patents

Description

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

  The chemically amplified photoresist composition generates an acid in the exposed area by irradiation with far ultraviolet rays and electron beams typified by KrF excimer laser light and ArF excimer laser light, and this acid is used as a catalyst to react with the exposed area. It is a composition that causes a difference in dissolution rate in the developer between the unexposed portion and the unexposed portion to form a resist pattern on the substrate.

  Such photoresist compositions are not only excellent in resolution performance, but also required performance such as smoothness of a resist pattern to be formed has been diversified. Various acid generators have been proposed in order to adjust the acid strength of the acid generated and the diffusion length and distribution in the resist film (see Patent Documents 1 to 5).

  However, as the pattern is further miniaturized, there is an increasing demand for suppressing the occurrence of development defects in the resist pattern to be formed. However, the conventional photoresist composition described above cannot sufficiently satisfy this requirement. Absent.

JP 2004-002252 A JP 2005-266766 A US Patent Application Publication No. 2006/0276670 JP 2007-145803 A JP 2008-094835 A

  This invention is made | formed based on the above situations, The objective is to provide the photoresist composition which can suppress generation | occurrence | production of a development defect.

（式（１）中、Ｒ^１は、炭素数３〜２０の１価の脂環式炭化水素基である。但し、この脂環式炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。また、この脂環式炭化水素基の炭素環に脂肪族複素環が縮環していてもよい。Ｘは、＊＊−（Ｘ^２−Ｒ’）_ｎ−Ｘ^１−である。Ｘ^１は、＊−ＣＯＯ−又は−Ｏ−である。Ｘ^２は、−ＣＯＯ−又は−Ｏ−である。Ｒ’は、炭素数３〜２０の２価の脂環式炭化水素基である。但し、この脂環式炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。また、この脂環式炭化水素基の炭素環に脂肪族複素環が縮環していてもよい。ｎは０又は１である。＊＊は、Ｒ^１に結合する部位を示す。＊は、Ｒ^１側に結合する部位を示す。Ｒ^２は、炭素数が偶数の２価の直鎖状炭化水素基又は炭素数が偶数の２価の直鎖状フッ素化炭化水素基である。Ｒ^３は、水素原子又はフッ素原子である。Ｍ^＋は、１価のカチオンである。） The invention made to solve the above problems is
[A] a polymer having a structural unit (I) containing an acid dissociable group (hereinafter, also referred to as “[A] polymer”), and [B] an acid generation containing a compound represented by the following formula (1) Agent (hereinafter also referred to as “[B] acid generator”)
Is a photoresist composition containing

(In formula (1), R ¹ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that a part or all of the hydrogen atoms of the alicyclic hydrocarbon group are substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group, X is **-(X ² -R ′) _n —X ¹ —. X ¹ is * —COO— or —O—, X ² is —COO— or —O—, and R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, some or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted, and an aliphatic heterocyclic ring is condensed to the carbocyclic ring of the alicyclic hydrocarbon group. which may be .n is 0 or 1. ** is. * is showing a site that binds to R ^1, .R ² showing a site that binds to R ¹ side is a divalent even number carbon atoms Straight chain .R ³ hydrocarbon group or the number of carbon atoms is a divalent linear fluorinated hydrocarbon radical even, a is .M ⁺ is hydrogen atom or a fluorine atom, a monovalent cation.)

The photoresist composition of this invention can suppress generation | occurrence | production of a development defect by containing the [B] acid generator which has the said specific structure with the [A] polymer. [B] The reason why the acid generator can suppress development defects due to the above-mentioned specific structure is not necessarily clear. For example, [B] the acid generator includes R ¹ —X and SO ₃ ^—. Have a structure through an odd number of carbon atoms, the affinity with the [A] polymer forming the resist film is considered to be increased. As a result, the [B] acid generator For example, the dispersibility in the resist film is improved.

（式（１−１）中、Ｒ^１、Ｘ及びＭ^＋は、上記式（１）と同義である。Ｒ^Ａは、メチレン基又は１，３−プロパンジイル基である。） The compound represented by the above formula (1) is preferably represented by the following formula (1-1).

(In formula (1-1), R ¹ , X and M ⁺ have the same meanings as in formula (1) above. R ^A represents a methylene group or a 1,3-propanediyl group.)

  According to the photoresist composition, since the [B] acid generator has the above specific structure, for example, there is a synergistic effect between the high dispersibility of the [B] acid generator and the appropriate strength of the generated acid. As a result, the occurrence of development defects is further suppressed.

（式（２−１）中、Ｒ^４、Ｒ^５及びＲ^６は、それぞれ独立して、炭素数１〜２０のアルキル基又は炭素数６〜３０のアリール基である。このアルキル基及びアリール基が有する水素原子の一部又は全部は置換されていてもよい。また、Ｒ^４、Ｒ^５及びＲ^６のうちのいずれか２つ以上が互いに結合して、これらが結合する硫黄原子と共に環構造を形成していてもよい。
式（２−２）中、Ｒ^７及びＲ^８は、それぞれ独立して、炭素数１〜２０のアルキル基又は炭素６〜３０のアリール基である。このアルキル基及びアリール基が有する水素原子の一部又は全部は置換されていてもよい。また、Ｒ^７及びＲ^８が互いに結合して、これらが結合するヨウ素原子と共に環構造を形成していてもよい。） M ⁺ in the above formula (1) is at least one cation 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). It is preferable.

(In formula (2-1), R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms. The alkyl group and aryl group Some or all of the hydrogen atoms contained in may be substituted, or any two or more of R ⁴ , R ⁵ and R ⁶ may be bonded to each other, and the ring structure together with the sulfur atom to which they are bonded May be formed.
In formula (2-2), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and aryl group may be substituted. R ⁷ and R ⁸ may be bonded to each other to form a ring structure together with the iodine atom to which they are bonded. )

  The said photoresist composition can improve a sensitivity because the [B] acid generator has the said specific cation, As a result, generation | occurrence | production of a development defect can further be suppressed.

（式（３）中、Ｒ^９は、水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｒ^１０、Ｒ^１１及びＲ^１２は、それぞれ独立して、炭素数１〜１０のアルキル基又は炭素数３〜２０の１価の脂環式炭化水素基である。但し、Ｒ^１１及びＲ^１２が互いに結合して、これらが結合する炭素原子と共に炭素数４〜２０の２価の脂環式炭化水素基を形成していてもよい。） The structural unit (I) is preferably 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 , R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms. Or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that R ¹¹ and R ¹² are bonded to each other, and the divalent alicyclic ring having 4 to 20 carbon atoms together with the carbon atom to which they are bonded. (Formula hydrocarbon groups may be formed)

  According to the photoresist composition, the dispersibility of the acid generator [B] in the resist film can be further improved by using the structural unit (I) of the polymer (A) as the specific structural unit. As a result, the occurrence of development defects can be further suppressed.

The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film on a substrate using the photoresist composition;
(2) a step of exposing the resist film through a photomask; and (3) a step of developing the exposed resist film.
According to the resist pattern forming method, since the above-described photoresist composition is used, a resist pattern with few development defects can be formed.

（式（１）中、Ｒ^１は、炭素数３〜２０の１価の脂環式炭化水素基である。但し、この脂環式炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。また、この脂環式炭化水素基の炭素環に脂肪族複素環が縮環していてもよい。Ｘは、＊＊−（Ｘ^２−Ｒ’）_ｎ−Ｘ^１−である。Ｘ^１は、＊−ＣＯＯ−又は−Ｏ−である。Ｘ^２は、−ＣＯＯ−又は−Ｏ−である。Ｒ’は、炭素数３〜２０の２価の脂環式炭化水素基である。但し、この脂環式炭化水素基が有する水素原子の一部又は全部は置換されていてもよい。また、この脂環式炭化水素基の炭素環に脂肪族複素環が縮環していてもよい。ｎは０又は１である。＊＊は、Ｒ^１に結合する部位を示す。＊は、Ｒ^１側に結合する部位を示す。Ｒ^２は、炭素数が偶数の２価の直鎖状炭化水素基又は炭素数が偶数の２価の直鎖状フッ素化炭化水素基である。Ｒ^３は、水素原子又はフッ素原子である。Ｍ^＋は、１価のカチオンである。） The acid generator of the present invention is
A compound represented by the following formula (1) is included.

(In formula (1), R ¹ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that a part or all of the hydrogen atoms of the alicyclic hydrocarbon group are substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group, X is **-(X ² -R ′) _n —X ¹ —. X ¹ is * —COO— or —O—, X ² is —COO— or —O—, and R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, some or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted, and an aliphatic heterocyclic ring is condensed to the carbocyclic ring of the alicyclic hydrocarbon group. which may be .n is 0 or 1. ** is. * is showing a site that binds to R ^1, .R ² showing a site that binds to R ¹ side is a divalent even number carbon atoms Straight chain .R ³ hydrocarbon group or the number of carbon atoms is a divalent linear fluorinated hydrocarbon radical even, a is .M ⁺ is hydrogen atom or a fluorine atom, a monovalent cation.)

  Since the said acid generator has the said specific structure, it can be used suitably as a component of a photoresist composition, As mentioned above, the photoresist composition which can suppress generation | occurrence | production of a development defect can be obtained.

  Here, the term “linear” of the hydrocarbon group and the fluorinated hydrocarbon group means that the hydrocarbon group and the fluorinated hydrocarbon group do not have a branched structure and have bonds at carbon atoms at both ends of the group.

  As described above, according to the photoresist composition and the resist pattern forming method of the present invention, a resist pattern with few development defects can be formed. Therefore, the photoresist composition, resist pattern forming method and acid generator of the present invention can be suitably used for forming a finer resist pattern.

<Photoresist composition>
The photoresist composition of the present invention contains a [A] polymer and a [B] acid generator. Moreover, the said photoresist composition may contain arbitrary components in the range which does not impair the effect of this invention. Hereinafter, each component will be described.

<[A] polymer>
[A] A polymer is a polymer which has structural unit (I) containing an acid dissociable group. The photoresist composition contains the [A] polymer, so that the acid dissociable group is dissociated by the action of the acid generated from the [B] acid generator, and the solubility of the [A] polymer in the developer. By changing, a resist pattern can be formed. Moreover, according to the said photoresist composition, it is thought that a [B] acid generator can be disperse | distributed moderately in the resist film formed by containing a [A] polymer, and is good resist. A pattern can be formed.

  [A] The polymer preferably has, in addition to the structural unit (I), a structural unit (II) containing at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. And may have a structural unit (III) containing a polar group.

[Structural unit (I)]
The structural unit (I) is a structural unit containing an acid dissociable group. The “acid-dissociable group” is a group that substitutes a hydrogen atom of a polar group such as a carboxy group or a hydroxy group, and is a group that is dissociated by the action of an acid generated from an acid generator or the like.

  As the structural unit (I), a structural unit represented by the above formula (3) (hereinafter also referred to as “structural unit (I-1)”) is preferable. It is considered that [A] the polymer has the structural unit (I-1) as the structural unit (I), for example, the dispersibility of the [B] acid generator in the resist film can be improved. The occurrence of development defects in the photoresist composition can be further suppressed.

In said formula (3), R < ⁹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ¹⁰ , R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, R ¹¹ and R ¹² may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.

R ⁹ is preferably a methyl group from the viewpoint of the copolymerizability of the monomer that gives the structural unit (I-1).

Examples of the alkyl group having 1 to 10 carbon atoms represented by R ¹⁰ , R ¹¹ and R ¹² include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group. , Sec-butyl group, t-butyl group and the like. In these, a methyl group, an ethyl group, and i-propyl group are preferable, and a methyl group and i-propyl group are more preferable.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹⁰ , R ¹¹ and R ¹² include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like. A monocyclic alicyclic hydrocarbon group; a polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecanyl group, and a tetracyclododecanyl group. Among these, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are preferable, and a cyclopentyl group and an adamantyl group are more preferable.

Examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms which are formed together with the carbon atom to which R ¹¹ and R ¹² are bonded to each other include, for example, a cyclobutanediyl group and a cyclopentanediyl group And monocyclic alicyclic hydrocarbon groups such as cyclohexanediyl group and cyclooctanediyl group; and polycyclic alicyclic hydrocarbon groups such as norbornanediyl group and adamantanediyl group. Among these, from the viewpoint of increasing the development defect suppression of the photoresist composition, cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group are preferable, and cyclopentanediyl group and adamantanediyl group are preferred. More preferred is a cyclopentanediyl group.

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

In said formula (3-1)-(3-4), R < ⁹ >, R < ¹⁰ >, R < ¹¹ > and R < ¹² > are synonymous with said formula (3). n _p is an integer of 1 to 4.

  Examples of the structural unit represented by the above formula (3) or (3-1) to (3-4) include a structural unit represented by the following formula.

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

  Among these, from the viewpoint of further improving the development defect suppression of the photoresist composition, the structural unit represented by the above formula (3-1) and the structural unit represented by the above formula (3-2) Preferably, the structural unit represented by the above formula (3-2) is more preferable, the structural unit derived from 1-methyl-cyclopentyl (meth) acrylate, the structural unit derived from 1-i-propyl-cyclopentyl (meth) acrylate. The structural unit derived from is more preferable.

  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, 30 mol%-70 mol% are more preferable, 35 mol% More preferred is ˜55 mol%. 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. On the contrary, when the content ratio of the structural unit (I) exceeds the above upper limit, the adhesion of the formed resist pattern may be lowered.

[Structural unit (II)]
The structural unit (II) is a structural unit including at least one structure selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. [A] When the polymer has the structural unit (II), basic resist characteristics such as adhesion to a resist film formed from the photoresist composition can be further improved. Further, the solubility of the resist film in the developer can be increased. A lactone structure, a cyclic carbonate structure and a sultone structure are respectively a lactone ring (one ring containing a bond represented by —O—C (O) —) and a cyclic carbonate ring (—O—C (O) —O—). And a sultone ring (one ring containing a bond represented by —O—S (O) ₂ —).

  As a structural unit which has the said lactone structure, the structural unit etc. which are represented by a following formula are mentioned, for example.

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

As said R ^<L1> , a methyl group is preferable from a copolymerizable viewpoint of the monomer which gives structural unit (II).

  Among these, as the structural unit (II) containing a lactone structure, a structural unit containing a norbornane lactone group is preferable, and a structural unit derived from norbornane lactonyl (meth) acrylate, norbornane lactonyloxycarbonylmethyl (meth) acrylate, Derived structural units are more preferred.

  Examples of the structural unit having the cyclic carbonate structure 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, as the structural unit (II) including a cyclic carbonate structure, a structural unit having an ethylene carbonate ring is preferable, and a structural unit derived from 1,2-propylene carbonate (meth) acrylate is more preferable.

  As structural unit (II) containing the said sultone structure, the structural unit etc. which are represented by a following formula are mentioned, for example.

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

  As a content rate of structural unit (II), 30 mol%-80 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 40 mol%-70 mol% are more preferable, 45 mol% More preferred is ~ 65 mol%. By making the content rate of structural unit (II) into the said range, the adhesiveness of the resist film formed from the said photoresist composition improves more.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) and (II). As said other structural unit, the structural unit etc. which have a polar group are mentioned, for example. Examples of the structural unit having a polar group 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. R ¹⁴ is a hydrogen atom or a methyl group.

  As a content rate of the said other 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. If the content ratio of the other structural units exceeds the upper limit, the pattern forming property of the photoresist composition may be lowered.

  [A] The content of the polymer is usually 70% by mass or more, preferably 80% by mass or more, and more preferably 85% by mass or more with respect to the total solid content of the photoresist composition.

<[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-cyclopropylpropylene). Pionitrile), azo radical initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile), 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 preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

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

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

  [A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 30,000 or less. Preferably, it is 3,000 or more and 20,000 or less. [A] If the Mw of the polymer is less than the lower limit, the heat resistance of the resulting resist film may be reduced. Conversely, if the Mw of the [A] polymer exceeds 50,000, the developability of the resist film may be reduced.

  [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, manufactured by Tosoh)
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

<[B] Acid generator>
[B] The acid generator is an acid generator containing a compound represented by the above formula (1). The said photoresist composition can suppress generation | occurrence | production of a development defect by containing the [B] acid generator as an acid generator with the said [A] polymer.

In the above formula (1), ^{R 1} is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, a part or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group. X ^{is, ** - (X 2 -R '} ) n -X 1 - it is. X ¹ is * —COO— or —O—. X ² is —COO— or —O—. R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, a part or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group. n is 0 or 1. ** indicates the site for binding to ^{R 1.} * Indicates a site binding to ^{R 1} side. R ² is a divalent linear hydrocarbon group having an even number of carbon atoms or a divalent linear fluorinated hydrocarbon group having an even number of carbon atoms. R ³ is a hydrogen atom or a fluorine atom. M ⁺ is a monovalent cation.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ¹ include monocyclic alicyclic groups such as a cyclopropyl group, a cyclobutyl group, a cyclopropyl group, and a cyclohexyl group. A hydrocarbon group; a polycyclic alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. Of these, a polycyclic alicyclic hydrocarbon group is preferable and an adamantyl group is more preferable from the viewpoint of further improving the development defect suppression of the photoresist composition.

  Examples of the substituent that the alicyclic hydrocarbon group may have include a hydroxy group, a cyano group, a halogen atom, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, and an acyl group.

  As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, for example.

  Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.

  Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and a propoxycarbonyl group.

  Examples of the alkoxycarbonyloxy group include a methoxycarbonyloxy group, an ethoxycarbonyloxy group, and a propoxycarbonyloxy group.

  Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group.

  Examples of the acyloxy group include an acetoxy group, a propionyloxy group, a butyryloxy group, and the like.

  Among the substituents that these alicyclic hydrocarbon groups may have, the acid polarity generated from the acid generator [B] is increased, so that the acid diffusion length is appropriately shortened. Groups are preferred.

Examples of the aliphatic heterocyclic ring that may be fused to the carbocyclic ring of the alicyclic hydrocarbon group include:
Cyclic ether rings represented by the following formulas (a-1) to (a-4);
A cyclic amine ring represented by the following formulas (b-1) and (b-2);
Cyclic sulfide rings represented by the following formulas (c-1) to (c-4);
A cyclic ketone ring represented by the following formulas (d-1) to (d-3);
A lactone ring represented by the following formulas (e-1) to (e-4);
Lactam rings represented by the following formulas (f-1) to (f-4);
A cyclic carbonate ring represented by the following formulas (g-1) to (g-3);
A cyclic carbamate ring represented by the following formulas (h-1) to (h-3);
A cyclic urea ring represented by the following formulas (i-1) to (i-3);
A cyclic sulfone ring represented by the following formulas (j-1) to (j-3);
Examples include sultone rings represented by the following formulas (k-1) to (k-3). The aliphatic heterocyclic ring may be condensed with a carbocyclic ring of the alicyclic hydrocarbon group sharing one carbon-carbon bond, or may be condensed with two or more carbon-carbon bonds. May be.

  Among these, as the aliphatic heterocyclic ring that may be condensed with the carbocyclic ring of the alicyclic hydrocarbon group, [B] from the viewpoint of appropriately shortening the diffusion length of the acid generated from the acid generator, A ring, a cyclic carbonate ring, a cyclic sulfone ring, and a sultone ring are preferable, a lactone ring is more preferable, a lactone ring represented by the above formula (e-2), and a lactone ring represented by the above formula (e-3) are further included. A lactone ring represented by the above formula (e-2) fused with a norbornyl group and a lactone ring represented by the above formula (e-3) fused with a cyclopentyl group are particularly preferable.

It said X ^{is, ** - (X 2 -R '} ) n -X 1 - is. ** indicates the site for binding to ^{R 1.} n is 0 or 1. That is, X is **-X ¹ -or **-X ² -R'-X ^1- . Examples of the divalent alicyclic hydrocarbon group represented by R ′ include groups obtained by removing one hydrogen atom from those exemplified as the monovalent alicyclic hydrocarbon group represented by R ¹ above. Can be mentioned. Examples of the substituent that the alicyclic hydrocarbon group may have include the same groups as those exemplified as the substituent of the monovalent alicyclic hydrocarbon group represented by R ¹ above. Can be mentioned. Examples of the aliphatic heterocyclic ring that may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group include a condensed carbocyclic ring of the monovalent alicyclic hydrocarbon group represented by R ¹ above. Examples thereof include the same rings as those exemplified as the aliphatic heterocyclic ring which may be included. R ′ is preferably a cycloalkanediyl group, more preferably a C3-C8 cycloalkanediyl group, and even more preferably a cyclohexanediyl group. X ¹ and X ² are preferably —COO— from the viewpoint of ease of synthesis of the [B] acid generator. n is preferably 0.

The number of carbon atoms of R ² is preferably an even number of 14 or less, more preferably an even number of 10 or less, and even more preferably 2, 4 and 6, from the viewpoint of higher development defect suppression of the photoresist composition. 2 and 4 are particularly preferred and 4 is most preferred.

Examples of the divalent linear hydrocarbon group having an even number of carbon atoms represented by R ² include 1,2-ethanediyl group, 1,4-butanediyl group, 1,6-hexanediyl group, 1, An 8-octanediyl group, a 1,10-decanediyl group and the like can be mentioned. Among these, 1,2-ethanediyl group is more preferable.

Examples of the divalent linear fluorinated hydrocarbon group having an even number of carbon atoms represented by R ² include 1-fluoro-1,2-ethanediyl group and 1,1-difluoro-1,2-ethanediyl. Group, 1,1,2,2-tetrafluoro-1,2-ethanediyl group, 1-fluoro-1,4-butanediyl group, 1,1-difluoro-1,4-butanediyl group, 1,1-difluoro- Examples include 1,6-hexanediyl group.

R ³ is preferably a fluorine atom from the viewpoint that the strength of the acid generated from the [B] acid generator is appropriately increased.

Examples of the group represented by —R ² —CFR ³ — include a 1-fluoro-1,3-propanediyl group, a 1,1-difluoro-1,3-propanediyl group, and a 1,1,2-trimethyl group. Fluoro-1,3-propanediyl group, 1,1,2,2-tetrafluoro-1,3-propanediyl group, 1,1,2,2,3,3-hexafluoro-1,3-propanediyl Group, 1-fluoro-1,5-pentanediyl group, 1,1-difluoro-1,5-pentanediyl group, 1,1,2-trifluoro-1,5-pentanediyl group, 1,1,2,2- Tetrafluoro-1,5-pentanediyl group, 1,1,2,2,3,3-hexafluoro-1,5-pentanediyl group, 1,1,2,2-tetrafluoro-1,7-heptanediyl group, 1,1,2,2-tetrafluoro-1 , 9-nonanediyl group, 1,1,2,2-tetrafluoro-1,11-undecandiyl group and the like. Among these, from the viewpoint that the acid generated from the [B] acid generator becomes moderately strong and, as a result, the development defect inhibiting property of the photoresist composition becomes higher, 1,1,2,2-tetrafluoro. -1,3-propanediyl group, 1,1,2,2-tetrafluoro-1,5-pentanediyl group, 1,1,2,2-tetrafluoro-1,7-heptanediyl group, 1,1,2 , 2-tetrafluoro-1,9-nonanediyl group is preferred.

  As the compound represented by the formula (1), for example, a synergistic effect of [B] high dispersibility of the acid generator and appropriate strength of the generated acid is exhibited. As a result, the photoresist composition From the viewpoint of further suppressing the occurrence of development defects, a compound represented by the above formula (1-1) is preferable.

In said formula (1-1), R ^{< 1 >} , X and M ^<+> are synonymous with the said Formula (1). R ^A is a methylene group or a 1,3-propanediyl group.

The ^RA is preferably a 1,3-propanediyl group from the viewpoint of further reducing development defects of a resist pattern formed from the photoresist composition.

Although it does not specifically limit as a monovalent cation represented by said M ^<+> , From a viewpoint which can improve the sensitivity of the said photoresist composition and can suppress generation | occurrence | production of a development defect as a result, following formula (2-1) And at least one cation selected from the group consisting of a iodonium cation represented by the following formula (2-2).

In the above formula ^{(2-1), R 4, R} 5 and ^{R 6} are each independently an alkyl group or an aryl group having 6 to 30 carbon atoms having 1 to 20 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and aryl group may be substituted. Further, any two or more of R ⁴ , R ⁵ and R ⁶ may be bonded to each other to form a ring structure together with the sulfur atom to which they are bonded.
In the above formula (2-2), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and aryl group may be substituted. R ⁷ and R ⁸ may be bonded to each other to form a ring structure together with the iodine atom to which they are bonded.

Examples of the alkyl group having 1 to 20 carbon atoms represented by R ⁴ , R ⁵ and R ⁶ , and R ⁷ and R ⁸ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, n -Butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-decyl group and the like can be mentioned.

Examples of the aryl group having 6 to 30 carbon atoms represented by R ⁴ , R ⁵ and R ⁶ , and R ⁷ and R ⁸ include a phenyl group, a tolyl group, a xylyl group, a mesityl group, a naphthyl group, and an anthranyl group. Etc.

Examples of the substituent that the alkyl group and aryl group may have include the same ones as the examples of the substituent that the alicyclic hydrocarbon group represented by R ¹ of the acid generator [B] has. It is done.

  As the sulfonium cation, a sulfonium cation represented by the following formula (2-1-1) and a sulfonium cation represented by the following formula (2-1-2) are preferable.

In the above formula (2-1-1), R ^a , R ^b and R ^c are each independently a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group which may have a substituent, or a cycloalkyl group. , An alkoxy group, a —S—R ^α group or a —SO ₂ —R ^β group. However, R ^α is an alkyl group or an aryl group which may have a substituent. ^Rβ is an alkyl group, cycloalkyl group, alkoxy group or aryl group which may have a substituent. n1, n2 and n3 are each independently an integer of 0 to 5.
In the above formula (2-1-2), ^{R d} represents a hydrogen atom, a linear or branched alkyl group or an aryl group having a carbon number of 6-8 having from 1 to 8 carbon atoms. However, one part or all part of the hydrogen atom which this alkyl group and aryl group have may be substituted. Also, when R ^d is plural, the plurality of R ^d may be the same or different, any two or more of the plurality of R ^d may be bonded to form a ring structure. R ^e is a hydrogen atom, a linear or branched alkyl group having 1 to 7 carbon atoms, or an aryl group having 6 or 7 carbon atoms. However, one part or all part of the hydrogen atom which this alkyl group and aryl group have may be substituted. Also, if R ^e is plural, the plurality of R ^e may be the same or different, or two or more may be bonded to form a ring structure among the plurality of R ^e. n4 is an integer of 0-7. n5 is an integer of 0-6. n6 is an integer of 0-3.

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

  Among these, the above formula (i-1), formula (i-2), formula (i-6), formula (i-8), formula (i-13), formula (i-19), formula ( i-25), formula (i-27), formula (i-29), formula (i-33), formula (i-51), formula (i-54), formula (i-55), formula (i -56) and a sulfonium cation represented by formula (i-57) are preferred, and a sulfonium cation represented by formula (i-1) is more preferred.

  As the iodonium cation, for example, a cation represented by the following formula (2-2-1) is preferable.

In the above formula (2-2-1), R ^h and R ^g are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms. It is. However, one part or all part of the hydrogen atom which this alkyl group and aryl group have may be substituted. If R ^h and R ^g is plural, respectively, each of the plurality of R ^h and R ^g may be the same or different, a plurality of R ^f, bonded two or more of R ^g each other to form a ring structure It may be. n7 and n8 are each independently an integer of 0 to 5.

  Examples of the iodonium cation include iodonium cations represented by the following formulas (ii-1) to (ii-39).

  Among these, iodonium cations represented by the above formulas (ii-1) and (ii-11) are preferable, and iodonium cations represented by the above formula (ii-1) are more preferable.

  [B] Examples of the acid generator include those containing compounds represented by the following formulas (b-1) to (b-16).

In the formulas (b-1) to (b-16), M ⁺ has the same meaning as the formula (1).

  Among these, the above formulas (b-1), (b-2), (b-5), (b-6), (b) from the viewpoint of further improving the development defect suppression of the photoresist composition. -9), (b-12) and (b-16) are preferable, and in the above formulas (b-1), (b-6), (b-9) and (b-16), Compounds represented by the respective formulas are more preferred, and compounds represented by the above formulas (b-1), (b-6) and (b-16) are more preferred.

  [B] The content of the acid generator is preferably 0.1 part by mass to 30 parts by mass, more preferably 0.2 part by mass to 20 parts by mass with respect to 100 parts by mass of the polymer [A]. More preferably, 5 parts by mass to 15 parts by mass is more preferable, and 2 parts by mass to 15 parts by mass is particularly preferable. [B] If the content of the acid generator is less than the lower limit, the sensitivity of the photoresist composition may be insufficient. [B] If the content of the acid generator exceeds the above upper limit, the pattern forming property of the photoresist composition may deteriorate.

<[B] Synthesis Method of Acid Generator>
[B] The compound constituting the acid generator can be synthesized according to the following scheme when, for example, n in the formula (1) is 0 and X ¹ is —COO—.

In the above ^formulas, R ^1, R 2, ^{R 3} and ^{M +} is as defined in the above formula (1).

A product obtained by reacting a bromo compound having a hydroxy group with sodium dithionite is oxidized with a hydrogen peroxide solution in the presence of a catalyst such as sodium tungstate to obtain a sodium sulfonate salt. It is done. From this sodium salt of sulfonic acid and a salt containing a monovalent cation represented by M ⁺ , a sulfonate containing M ⁺ as a cation is obtained, and the hydroxy group of this sulfonate is converted using a carboxylic acid. By esterification, the compound represented by the above formula (1) can be obtained. In addition to the reaction sequence of the above scheme, the compound represented by the above formula (1) may be prepared by, for example, forming an ester compound from the bromo compound having a hydroxy group and the carboxylic acid, then sodium dithionite, Subsequently, it can be synthesized by forming a sulfo group by reacting with hydrogen peroxide. In addition, a compound in which n in the above formula (1) is 0 and X ¹ is —O— and a compound in which n in the above formula (1) is 1 can also be synthesized according to the above scheme. .

<Optional component>
[[C] Fluorine atom-containing polymer]
[C] The fluorine atom-containing polymer is a polymer having a higher fluorine atom content than the [A] polymer. The photoresist composition contains a [C] fluorine atom-containing polymer, so that when the resist film is formed, the distribution of the resist film surface layer depends on the oil-repellent characteristics of the [C] fluorine atom-containing polymer. Therefore, at the time of immersion exposure, elution of the acid generator and acid diffusion control agent in the film into the immersion medium can be suppressed. Further, due to the water-repellent characteristics of the [C] fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. In addition, the receding contact angle between the resist film and the immersion medium can be increased, and as a result, high-speed scanning exposure is possible without leaving water droplets. Thus, when the said photoresist composition contains a [C] fluorine atom containing polymer, the resist film suitable for an immersion exposure method can be formed. In addition, the fluorine atom content rate (mass%) of a polymer can be calculated | required by identifying the structure of a polymer by < ¹³ > C-NMR measurement.

  [C] The fluorine atom-containing polymer is not particularly limited as long as it is a polymer containing a fluorine atom, but is usually formed by polymerizing one or more monomers containing fluorine atoms in the structure. be able to. Examples of the monomer containing a fluorine atom in the structure include those containing a fluorine atom in the main chain, those containing a fluorine atom in the side chain, and those containing a fluorine atom in the main chain and the side chain.

  Examples of the monomer containing a fluorine atom in the main chain include an α-fluoroacrylate compound, an α-trifluoromethyl acrylate compound, a β-fluoroacrylate compound, a β-trifluoromethyl acrylate compound, and an α, β-fluoroacrylate compound. , Α, β-trifluoromethyl acrylate compounds, compounds in which one or more types of vinyl moiety hydrogen are substituted with fluorine atoms or trifluoromethyl groups, and the like.

  Examples of the monomer containing a fluorine atom in the side chain include those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorine atom, a fluoroalkyl group or a derivative thereof, acrylic acid or methacrylic acid, and a fluoroalkyl. Examples include ester compounds formed from alcohols and derivatives thereof, one or more olefin side chains (sites not including double bonds) being fluorine atoms, fluoroalkyl groups or derivatives thereof.

  Examples of monomers containing fluorine atoms in the main chain and side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β-trifluoro An ester compound formed from methylacrylic acid, α, β-ditrifluoromethylacrylic acid, etc., and a fluoroalkyl alcohol or a derivative thereof, and hydrogen in one or more kinds of vinyl sites is substituted with a fluorine atom or a trifluoromethyl group A compound in which the side chain of the compound is substituted with a fluorine atom or a fluoroalkyl group or a derivative thereof, and hydrogen bonded to a double bond of one or more alicyclic olefin compounds is substituted with a fluorine atom or a trifluoromethyl group And those whose side chain is a fluoroalkyl group or a derivative thereof. In addition, this alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  In the fluorine atom-containing polymer, the structural unit to which a fluorine atom is imparted is not particularly limited. However, the structural unit represented by the following formula (C1) (hereinafter referred to as “structural unit (CI)”) Is preferably used as the fluorine atom-providing structural unit.

In the above formula (C1), R ⁱ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a single bond or a divalent linking group. R ¹⁵ is a linear or branched alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative thereof. .

  Examples of the divalent linking group represented by A include an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

  Preferred monomers that give the structural unit (CI) include trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, and 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) acrylate, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylate, 1- (2,2,3,3, 4,4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) ) Acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6 , 6-octafluorohexyl) (meth) acrylic acid ester and the like.

  In the fluorine atom-containing polymer, the content ratio of the structural unit (C-I) is usually 5 mol% or more, preferably 10 mol% or more, more preferably, with respect to all the structural units in the fluorine atom-containing polymer. It is 15 mol% or more. If the content ratio of the structural unit (EI) is less than 5 mol%, a receding contact angle of 70 ° or more may not be achieved, and elution of the acid generator and the like from the resist film may not be suppressed. The said fluorine atom containing polymer may contain 1 type of structural units (EI), and may contain 2 or more types.

  In addition to the structural unit having a fluorine atom in the structure, the fluorine atom-containing polymer includes, for example, a structural unit having an acid dissociable group for controlling the dissolution rate in a developer, a lactone skeleton, a hydroxyl group, In order to suppress scattering of light due to structural units having a carboxyl group or the like, or structural units having an alicyclic compound, or reflection from the substrate, “other structural units” such as structural units derived from aromatic compounds are 1 More than one kind can be contained.

  Examples of the structural unit having a dissociable group include a structural unit represented by the following formula (C2) (hereinafter also referred to as “structural unit (C-II)”).

In said formula (C2), ^Rj is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^q1 , R ^q2 and R ^q3 are each independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl having 1 to 4 carbon atoms. It is a group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^q1 , R ^q2 and R ^q3 include norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclobutane and cyclopentane. , A group derived from an alicyclic ring such as cycloalkane such as cyclohexane, cycloheptane, cyclooctane, etc .; a part or all of the hydrogen atoms of the group derived from these alicyclic rings may be, for example, a methyl group, ethyl A linear or branched alkyl group having 1 to 4 carbon atoms such as a group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, etc. Or a group substituted with one or more cycloalkyl groups having 3 to 10 carbon atoms such as a cyclobutyl group and a cyclohexyl group. Further, any two of R ^{q1 to} R ^q3 may be bonded to each other to form a divalent alicyclic hydrocarbon group or a derivative group thereof together with the carbon atom to which each is bonded. Of these alicyclic hydrocarbon groups, norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane, or a group derived from an alicyclic ring of cyclohexane, or a hydrogen derived from these alicyclic rings A group in which an atom is substituted with the above alkyl group is preferable.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms represented by R ^q1 , R ^q2 and R ^q3 include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n -Butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like can be mentioned.

  In the above formula (C2), preferred examples of the acid dissociable group, that is, the group bonded to the oxygen atom of the ester group include a t-butyl group, a 1-n- (1-ethyl-1-methyl) propyl group, 1-n- (1,1-dimethyl) propyl group, 1-n- (1,1-dimethyl) butyl group, 1-n- (1,1-dimethyl) pentyl group, 1- (1,1-diethyl) ) Propyl group, 1-n- (1,1-diethyl) butyl group, 1-n- (1,1-diethyl) pentyl group, 1- (1-methyl) cyclopentyl group, 1- (1-ethyl) cyclopentyl Group, 1- (1-n-propyl) cyclopentyl group, 1- (1-i-propyl) cyclopentyl group, 1- (1-methyl) cyclohexyl group, 1- (1-ethyl) cyclohexyl group, 1- (1 -N-propyl) cyclohexyl group, 1- 1-i-propyl) cyclohexyl group, 1- {1-methyl-1- (2-norbornyl)} ethyl group, 1- {1-methyl-1- (2-tetracyclodecanyl)} ethyl group, 1- {1-methyl-1- (1-adamantyl)} ethyl group, 2- (2-methyl) norbornyl group, 2- (2-ethyl) norbornyl group, 2- (2-n-propyl) norbornyl group, 2- (2-i-propyl) norbornyl group, 2- (2-methyl) tetracyclodecanyl group, 2- (2-ethyl) tetracyclodecanyl group, 2- (2-n-propyl) tetracyclodecanyl group 2- (2-i-propyl) tetracyclodecanyl group, 1- (1-methyl) adamantyl group, 1- (1-ethyl) adamantyl group, 1- (1-n-propyl) adamantyl group, 1- (1-i-propyl) adaman Group consisting of these alicyclic rings, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, Examples include a group substituted with one or more of a linear or branched alkyl group having 1 to 4 carbon atoms, such as a t-butyl group, or a cyclic alkyl group having 3 to 10 carbon atoms. .

Preferred monomers that give the structural unit (C-II) include (meth) acrylic acid 2-methyladamantyl-2-yl ester and (meth) acrylic acid 2-methyl-3-hydroxyadamantyl-2-yl ester. (Meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyl-3-hydroxyadamantyl-2-yl ester, (meth) acrylic acid 2-n-propyladamantyl-2-yl ester Ester, (meth) acrylic acid 2-isopropyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethyl ester Bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-8-methyltricyclo [5.2. .0 ^2,6] decan-8-yl ester, (meth) ethyl-8-acrylic acid tricyclo [5.2.1.0 ^2,6] decan-8-yl ester, (meth) acrylic acid -4 -Methyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid-4-ethyltetracyclo [6.2.1 ^3,6 . 02,7] dodecan-4-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tricyclo [ 5.2.1.0 ^2,6 ] decan-8-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tetracyclo [6.2.1 ^3,6.0 0.0 ^2,7 ] dodecane- 4-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1- (3-hydroxyadamantan-1-yl)- 1-methylethyl ester, (meth) acrylic acid 1,1-dicyclohexylethyl ester, (meth) acrylic acid 1,1-di (bicyclo [2.2.1] hept-2-yl) ethyl ester, ( Data) acrylic acid 1,1-di (tricyclo [5.2.1.0 ^2,6] decan-8-yl) ethyl ester, (meth) acrylic acid 1,1-di (tetracyclo [6.2.1 ^3,6 .0 ^2,7] dodecane-4-yl) ethyl ester, (meth) acrylic acid 1,1-di (adamantan-1-yl) ethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl Examples include esters, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like.

  Among these monomers, (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2 2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2. 1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (Meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-e -1-cyclohexyl ester.

  As the structural unit having the lactone skeleton, those similar to the structural unit (II) of the [A] polymer can be used. (Hereinafter also referred to as “structural unit (C-III)”)

  Examples of the structural unit having the alicyclic group include a structural unit represented by the following formula (C4) (hereinafter also referred to as “structural unit (C-IV)”).

In the above formula (C4), R ^k represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ¹⁶ is a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ¹⁶ include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. 2] Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . Hydrocarbon groups derived from alicyclic rings of cycloalkanes such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane. The carbon hydrogen group derived from these cycloalkane-derived alicyclic rings may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group. 1 type or more of C1-C4 linear or branched alkyl groups, such as 2-methylpropyl group, 1-methylpropyl group, t-butyl group, or C3-C10 cycloalkyl group, or 1 It may be substituted with more than one. The substituents are not limited to these alkyl groups and cycloalkyl groups, and may be those substituted with a hydroxyl group, a cyano group, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyl group, or an oxygen atom. .

Preferred monomers that give the structural unit (C-IV) include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester and (meth) acrylic acid-bicyclo [2.2. 2] Oct-2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.02,6] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.13, 6.0 ^2,7 ] dodec-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3. 3.1.1 ^3,7 ] dec-2-yl ester and the like.

  Moreover, as a preferable monomer which gives the structural unit (henceforth "structural unit (CV)") derived from the said aromatic compound, styrene, (alpha) -methylstyrene, 2-methylstyrene, 3 -Methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxy Styrene, 2-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene, 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl -3-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4 Hydroxystyrene, 3,4-dihydroxystyrene, 2,4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene 4- (2-ethyl-2-propoxy) -α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, ( Meth) acrylic acid benzyl, acenaphthylene, 5-hydroxyacenaphthylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 1-anthryl (meth) acrylate, 2 -Anthryl (meth) acrylate, 9-anthryl (meth) acrylate, 9-anthrylmethyl (meth) acrylate, 1-vinylpyrene, etc. are mentioned.

  As the “other structural unit” possessed by the [C] fluorine atom-containing polymer, the structural unit (C-II), the structural unit (C-III), the structural unit (C-IV), and the structural unit (CV) May have only 1 type, and may have 2 or more types. In the above [C] fluorine atom-containing polymer, the content ratio of these other structural units is usually 80 mol% or less, preferably 75 mol%, based on all the structural units constituting the [C] fluorine atom-containing polymer. Hereinafter, it is 70 mol% or less more preferably.

  [C] The content of the fluorine atom-containing polymer is preferably 0 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and 1 part by mass with respect to 100 parts by mass of the polymer [A]. More preferably, it is 10 mass parts. [C] By making content of a fluorine atom containing polymer into the said range, the said photoresist composition can form a suitable resist film by immersion exposure.

<[C] Method for Synthesizing Fluorine Atom-Containing Polymer>
[C] The fluorine atom-containing polymer is obtained by polymerizing, for example, a monomer that gives each predetermined structural unit in a suitable solvent using a radical polymerization initiator in the same manner as the above-mentioned [A] polymer. Can be synthesized.

[[D] acid diffusion controller]
[D] The acid diffusion controlling agent controls the diffusion phenomenon in the resist film of the acid generated from [B] acid generator and the like by exposure, and has the effect of suppressing undesirable chemical reaction in the non-exposed region. The storage stability of the resist composition is further improved, the resolution of the resist is further improved, and changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed. A very excellent composition.

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

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, 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-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1, -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 the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-4-hydroxypiperidine, and Nt-butines such as Nt-amyloxycarbonyl-4-hydroxypiperidine. Amyloxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N- Examples include acetyl-1-adamantylamine, isocyanuric acid tris (2-hydroxyethyl), and the like. Among these, Nt-butoxycarbonyl group-containing amino compounds and Nt-amyloxycarbonyl group-containing amino compounds are preferable, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl- 4-hydroxypiperidine is more preferred.

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

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 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 etc. are mentioned.

  Further, as the [D] acid diffusion control agent, a photodisintegratable base that is exposed to light and generates a weak acid by exposure can also be used. 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 (D1), an iodonium salt compound represented by the following formula (D2), and the like.

In the above formula (D1) and formula (D2), R ^{17 to} R ²¹ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. Z ⁻ and E ⁻ are each independently an anion represented by OH ⁻ , R ^H —COO ⁻ , R ^H —SO ₃ ^— or the following formula (D3). However, ^RH is an alkyl group, an aryl group, or an aralkyl group.

In the above formula (D3), R ²² is a linear or branched alkyl group having 1 to 12 carbon atoms or a carbon atom having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms. It is a linear or branched alkoxyl group. u is an integer of 0-2.

  Among these, those containing an anion represented by the formula (D3) are preferable among these, and triphenylsulfonium salicylate is more preferable.

  The content of the [D] acid diffusion control agent in the photoresist composition is preferably less than 10 parts by mass and more preferably less than 8 parts by mass with respect to 100 parts by mass of the [A] polymer. [D] When the content of the acid diffusion controller exceeds 10 parts by mass, the sensitivity of the photoresist composition tends to decrease. The photoresist composition may contain one or more [D] acid diffusion control agents.

[[E] solvent]
The photoresist composition usually contains an [E] solvent. [E] The solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer, the [B] acid generator, and optional components contained as necessary.

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

  Examples of the ether solvent include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether, methoxybenzene, anisole (methylphenyl ether) and the like.

  Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone (2-heptanone), ethyl-n-butyl ketone. , Ketones such as methyl-n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone And system solvents.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec sec -Butyl, n-pentyl acetate, i-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-acetate -Nonyl, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoe Til ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl Ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate , N-amyl lactate, diethyl malonate, dimethyl phthalate, diethyl phthalate, etc. .

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

  Among these, ester solvents and ketone solvents are preferable, and propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone are more preferable. The photoresist composition may contain one or more [E] solvents.

[Other optional ingredients]
The photoresist composition may contain other optional components in addition to the components [A] to [E]. Examples of the other optional components include acid generators other than [B] acid generators, surfactants, and alicyclic skeleton-containing compounds. Each of these other optional components may be used alone or in combination of two or more.

[Other acid generators]
If the said photoresist composition is a small quantity of the range which does not impair the effect of this invention, you may contain other acid generators other than the said [B] acid generator. Other acid generators include, for example, [B] onium salt compounds other than acid generators, sulfone compounds, sulfonic acid ester compounds, N-sulfonyloxyimide compounds, diazomethane compounds, disulfonylmethane compounds, oxylsulfonate compounds, hydrazines Examples include sulfonate compounds.

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

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

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

[Sensitizer]
The sensitizer exhibits an effect of increasing the amount of acid generated from the [B] acid generator and the like, and has an 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 alone or in combination of two or more. As content of the sensitizer in the said photoresist composition, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing photoresist composition>
The said photoresist composition can be prepared by mixing a [A] polymer, a [B] acid generator, the arbitrary component contained as needed, and a [E] solvent in a predetermined ratio, for example. The photoresist composition is preferably filtered, for example, with a filter having a pore size of about 0.2 μm after mixing. The total solid concentration of the photoresist composition is usually 0.5% by mass to 50% by mass, preferably 1% by mass to 25% by mass.

<Resist pattern formation method>
The resist pattern forming method of the present invention comprises:
(1) A step of forming a resist film on a substrate using the photoresist composition;
(2) a step of exposing the resist film through a photomask; and (3) a step of developing the exposed resist film.

  According to the resist pattern forming method, since the photoresist composition described above is used, a resist pattern with few development defects can be formed. Hereinafter, each step will be described.

[(1) Process]
In the step (1), the photoresist composition is applied onto the substrate by an appropriate application means such as spin coating, cast coating, roll coating or the like, thereby forming a resist film. Examples of the substrate include a silicon wafer, silicon dioxide, a wafer coated with an antireflection film, and the like. Specifically, after applying the photoresist so that the resulting resist film has a predetermined thickness, the solvent in the coating film is vaporized by soft baking (SB) to form a resist film. As temperature of SB, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The SB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[(2) Process]
In the step (2), the resist film formed in the step (1) is exposed by irradiating with exposure light through a photomask (in some cases through an immersion medium such as water). In this case, exposure light is irradiated through a mask having a predetermined pattern. The exposure light is appropriately selected and irradiated from, for example, visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams, etc. according to the line width of the target pattern. Among these, far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm) are preferable, and ArF excimer laser light is particularly preferable.

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

[(3) Process]
In step (3), the exposed resist film is developed with a developer to form a predetermined resist pattern. After development, it is common to wash with water and dry. Examples of the developer include 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] An aqueous alkali solution in which at least one of alkaline compounds such as 5-nonene is dissolved is preferable. In addition, as a developer, an organic solvent such as a hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent, an alcohol solvent, or a solvent containing an organic solvent can be used.

  In addition, when performing immersion exposure, before the step (2), in order to protect the direct contact between the immersion liquid and the resist film, an immersion protective film insoluble in the immersion liquid is formed on the resist film. May be provided. Examples of the immersion protective film include a solvent peeling type protective film that peels off with a solvent before the step (3) (see, for example, JP-A-2006-227632), and a developer peeling type that peels off simultaneously with the development in the step (3). Any of the protective films (see, for example, WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

<Acid generator>
The acid generator of the present invention is an acid generator containing a compound represented by the above formula (1).

In the above formula (1), ^{R 1} is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, a part or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group. X ^{is, ** - (X 2 -R '} ) n -X 1 - it is. X ¹ is * —COO— or —O—. X ² is —COO— or —O—. R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, a part or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group. n is 0 or 1. ** indicates the site for binding to ^{R 1.} * Indicates a site binding to ^{R 1} side. R ² is a divalent linear hydrocarbon group having an even number of carbon atoms or a divalent linear fluorinated hydrocarbon group having an even number of carbon atoms. R ³ is a hydrogen atom or a fluorine atom. M ⁺ is a monovalent cation.

  Since the acid generator has been described as the [B] acid generator of the photoresist composition, description thereof is omitted here.

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

[Mw and Mn]
The measurement of Mw and Mn of the polymer was performed according to the method described above in the specification.

[ ¹ H-NMR analysis, ¹³ C-NMR analysis and ¹⁹ F-NMR analysis]
¹ H-NMR analysis, ¹³ C-NMR analysis, and ¹⁹ F-NMR analysis were measured using a nuclear magnetic resonance apparatus (JNM-EX270, manufactured by JEOL Ltd.).

<Synthesis of compounds>
[Example 1] (Synthesis of Compound (B-1))
The following compound (B-1) was synthesized according to the following scheme.

(Synthesis of Compound (b2))
In a flask equipped with a thermometer and a condenser, 10.0 g of 5-bromo-4,4,5,5-tetrafluoropentan-1-ol (the above compound (b1)), 5.98 g of sodium bicarbonate, dithionite Sodium 10.92 g, acetonitrile 20 mL and water 15 mL were added, and the reaction was performed at 64 ° C. for 10 hours in a nitrogen atmosphere. ^The disappearance of the raw material was confirmed by ¹⁹ F-NMR, and the reaction was completed. Thereafter, acetonitrile was distilled off under reduced pressure, and without further purification, an aqueous solution of the crude product of compound (b2) was obtained.

(Synthesis of Compound (b3))
A glass flask equipped with a thermometer and a condenser was charged with a total amount of the aqueous solution of the crude product of the compound (b2) obtained above and a catalytic amount of sodium tungstate (IV) dihydrate, and then 35 masses. % Hydrogen peroxide solution (5.09 g) was added dropwise. After stirring at room temperature for 5 hours, disappearance of the raw materials was confirmed by ¹⁹ F-NMR, and the reaction was completed. After completion of the reaction, 20 mL of water was further added, and the obtained aqueous layer was washed 5 times with 30 mL of dichloromethane to obtain an aqueous solution of the compound (b3).

(Synthesis of Compound (b4))
A flask equipped with a thermometer and a condenser was charged with the total amount of the aqueous solution of the compound (b3) obtained above and 18.82 g of triphenylsulfonium chloride, and then stirred at room temperature for 6 hours. Thereafter, the reaction solution was extracted with 100 mL of dichloromethane three times, and the obtained organic layer was washed with 150 mL of water six times. Dichloromethane was distilled off under reduced pressure from the obtained organic layer to obtain 17.51 g of compound (b4).

(Synthesis of Compound (B-1))
In a flask equipped with a thermometer and a condenser, 5 g of the compound (b4) obtained above and 4.29 g of 1-adamantanecarbonyl chloride were dissolved in a mixed solvent of 100 mL of methanol and 50 mL of dichloromethane. Thereafter, 3.27 g of triethylamine was added dropwise in an ice bath. After completion of the dropwise addition, the mixture was stirred at room temperature for 6 hours, and an aqueous sodium hydrogen carbonate solution was added to complete the reaction. The resulting solution was washed once with an aqueous sodium hydrogen carbonate solution and 10 times with water to recover a dichloromethane solution. Dichloromethane was distilled off under reduced pressure to obtain 6.6 g of compound (B-1) (yield 92% with respect to compound (b1), purity 98%).

[Example 2] (Synthesis of Compound (B-2))
The following compound (B-2) was synthesized according to the following scheme.

(Synthesis of Compound (b5))
In a flask equipped with a thermometer and a condenser, 4 g of the above compound (b1), 287 mg of p-toluenesulfonic acid and 3.94 g of 3-hydroxy-1-adamantanecarboxylic acid were dissolved in 400 mL of toluene. After reacting at 120 ° C. for 12 hours, the mixture was cooled to room temperature. Further, toluene was distilled off under reduced pressure, and 100 mL of dichloromethane was added for dissolution, followed by washing once with an aqueous sodium bicarbonate solution and twice with water. Dichloromethane was distilled off from the obtained organic layer under reduced pressure to obtain 6.63 g of compound (b5).

(Synthesis of Compound (B-2))
Using the obtained compound (b5), the same operation as in the synthesis of compound (B-1) from compound (b2) of Example 1 was carried out, and compound (B-2) was recovered from (compound (b1)). Yield 81%, purity 92%).

[Example 3] (Synthesis of Compound (B-3))
The same operation as in Example 1 was carried out except that 3-bromo-2,2,3,3-tetrafluoropropan-1-ol was used in place of the compound (b1) in Example 1, and the following compound (B -3) was obtained (yield 88% based on compound (b1)).

<Synthesis of [A] polymer and [C] fluorine atom-containing polymer>
The monomers used for the synthesis of [A] polymer and [C] fluorine atom-containing polymer are shown below.

  The compounds (M-1), (M-2), (M-3) and (M-6) are structural units (I), and the compounds (M-4) and (M-5) are structural units. (II) is given respectively.

<[A] Synthesis of polymer>
[Synthesis Example 1] (Synthesis of polymer (A-1))
21.54 g (50 mol%) of the above compound (M-1) as a monomer and 28.46 g (50 mol%) of the compound (M-5) are dissolved in 100 g of 2-butanone, and further as a polymerization initiator. A monomer solution in which 4.21 g of AIBN (5 mol% with respect to the total number of moles of monomers) was dissolved was prepared. A 500 mL three-necked flask charged with 50 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling, charged into a mixed solvent of 800 g of methanol and 200 g of water, and the precipitated white powder was filtered off. The filtered white powder was dispersed in 200 g of methanol, washed in the form of a slurry and then filtered, and then filtered twice, followed by vacuum drying at 50 ° C. for 17 hours to obtain a white powder polymer (A-1 (37.5 g, yield 75%). Mw of the polymer (A-1) was 5,100, and Mw / Mn was 1.34. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from the compound (M-1): the structural unit derived from the compound (M-5) was 48:52 (mol%).

[Synthesis Examples 2 to 5] (Polymers (A-2) to (A-5)
Polymers (A-2) to (A-5) were obtained in the same manner as in Synthesis Example 1 except that the types and amounts of monomers and polymerization initiators listed in Table 1 were used. Moreover, the content rate of each structural unit of each obtained polymer, Mw, Mw / Mn ratio, and a yield (%) are shown according to Table 1.

<Synthesis of [C] fluorine atom-containing polymer>
[Synthesis Example 4] (Synthesis of Polymer (C-1))
37.41 g (40 mol%) of the above compound (M-6) and 62.59 g (60 mol%) of the compound (M-7) are dissolved in 100 g of 2-butanone, and 4.79 g (7 mol%) of AIBN is further dissolved. A monomer solution was prepared. A 1,000 mL three-necked flask charged with 100 g of 2-butanone was purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction vessel was heated to 80 ° C. with stirring, and the monomer solution was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower. The polymerization reaction solution was concentrated under reduced pressure using an evaporator until the mass became 150 g. Thereafter, the concentrated solution was put into a mixed solution of 760 g of methanol and 40 g of water to precipitate a slime-like white solid. The liquid part was removed by decantation, and the collected solid was vacuum-dried at 50 ° C. for 17 hours to obtain a white powder polymer (C-1) (47 g, yield 47%). Mw of the polymer (C-1) was 3,700, and Mw / Mn was 1.40. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from the compound (M-6): the structural unit derived from the compound (M-7) was 42.5: 57.5 (mol%). there were.

<Preparation of photoresist composition>
The components constituting the photoresist composition other than the [A] polymer and the [C] fluorine atom-containing polymer are shown below.

[[B] component]
B-1: Triphenylsulfonium 1,1,2,2-tetrafluoro-5- (1-adamantanecarbonyloxy) pentane-1-sulfonate (compound (B-1) synthesized in Example 1 above)
B-2: Triphenylsulfonium 1,1,2,2-tetrafluoro-5- (3-hydroxy-1-adamantanecarbonyloxy) pentane-1-sulfonate (compound (B-2) synthesized in Example 2 above) )
B-3: Triphenylsulfonium 1,1,2,2-tetrafluoro-3- (1-adamantanecarbonyloxy) propane-1-sulfonate (compound (B-3) synthesized in Example 3 above)
B-4: Triphenylsulfonium 1,1,2,2-tetrafluoro-5- (2- (2-norbornanelactoneoxycarbonyl) cyclohexanecarbonyloxy) pentane-1-sulfonate (represented by the following formula (B-4) Compound)
b-1: triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) hexane-1-sulfonate b-2: triphenylsulfonium 1,1,2,2-tetrafluoro- 4- (1-adamantanecarbonyloxy) butane-1-sulfonate

[[D] acid diffusion controller]
D-1: Triphenylsulfonium salicylate (compound represented by the following formula (D-1))

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 4]
[A] 100 parts by mass of (A-1) as a polymer, [B] 10.4 parts by mass of (B-1) as an acid generator, [C] 3 parts by mass of (C-1) as a polymer [D] 7.3 parts by mass as an acid diffusion controller, (E-1) 2,600 parts by mass as (E) solvent, (E-2) 1,100 parts by mass and (E-3) 200 parts by mass was mixed to obtain a uniform solution. Then, the photoresist composition (J-1) was prepared by filtering using a membrane filter with a hole diameter of 200 nm. The solids concentration of the photoresist composition was about 4%.

[Examples 5 to 17 and Comparative Examples 1 to 10]
The photoresist compositions (J-2) to (J-14) of the examples and the (CJ of the comparative examples) were operated in the same manner as in Example 1 except that the components of the types and amounts shown in Table 2 were used. -1) to (CJ-10) were prepared.

<Formation of resist pattern>
On the 12-inch silicon wafer on which the lower antireflection film (ARC66, manufactured by Nissan Chemical Industries) was formed, the above-obtained photoresist compositions of Examples and Comparative Examples were respectively applied, and SB was performed at 120 ° C. for 60 seconds. A resist film having a thickness of 75 nm was formed. Next, an ArF excimer laser immersion exposure apparatus (NSR-S610C, manufactured by NIKON) was used for this resist film, and the pattern dimensions were determined according to the conditions of NA = 1.3, iNA = 1.27, ratio = 0.800, and Crosspore. It exposed through the mask of 45nm1L / 1S. After the exposure, PEB was performed for 60 seconds at the temperature described in Table 2. Thereafter, development, washing with water, and drying were performed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution to form a positive resist pattern.

<Evaluation>
Defects in the exposed portions of the resist pattern formed above were measured using a defect detection apparatus (KLA2351, manufactured by KLA TENCOR). Further, the detected defects are classified into those that are determined as resist-derived development defects and externally derived particle defects using a defect evaluation apparatus (SEM Vision G3, manufactured by KLA Tencor), and the number of resist-derived development defects. Was the number of development defects (unit: pieces / wafer). The numerical values of the number of development defects are shown in Table 2.

  As is clear from Table 2, it was confirmed that the number of development defects can be greatly reduced according to the photoresist compositions of the examples as compared with the photoresist compositions of the comparative examples.

  ADVANTAGE OF THE INVENTION According to this invention, the photoresist composition and resist pattern formation method which can suppress generation | occurrence | production of a development defect can be provided. Further, the acid generator of the present invention can be suitably used as a component of this photoresist composition. Therefore, the photoresist composition, the resist pattern forming method, and the acid generator can be suitably used in pattern formation in the semiconductor field and the like that will be increasingly miniaturized in the future.

Claims (7)

[A] A photoresist composition containing a polymer having a structural unit (I) containing an acid dissociable group, and [B] an acid generator containing a compound represented by the following formula (1).

(In formula (1), R ¹ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that a part or all of the hydrogen atoms of the alicyclic hydrocarbon group are substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group, X is **-(X ² -R ′) _n —X ¹ —. X ¹ is * —COO— or —O—, X ² is —COO— or —O—, and R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, some or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted, and an aliphatic heterocyclic ring is condensed to the carbocyclic ring of the alicyclic hydrocarbon group. which may be .n is 0 or 1 ** represents a site that binds to ^{R 1} * is .R ² showing a site that binds to ^{R 1} side is at least -CFR ³ -.. the side A divalent linear fluorinated hydrocarbon group having an even number of carbon atoms in which two fluorine atoms are bonded to a terminal carbon atom, R ³ is a fluorine atom , M ⁺ is a monovalent cation .) R in the above formula (1) ² Are 1,1-difluoro-1,2-ethanediyl group, 1,1,2,2-tetrafluoro-1,2-ethanediyl group, 1,1-difluoro-1,4-butanediyl group, 1,1, The 2,2-tetrafluoro-1,4-butanediyl group, 1,1-difluoro-1,6-hexanediyl group, or 1,1-difluoro-1,8-octanediyl group. Photoresist composition. The photoresist composition according to claim 1, wherein the compound represented by the formula (1) is represented by the following formula (1-1).

(In formula (1-1), R ¹ , X and M ⁺ have the same meanings as in formula (1) above. R ^A represents a methylene group or a 1,3-propanediyl group.) M ⁺ in the above formula (1) is at least one cation 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 claim 1 , claim 2 or claim 3 .

(In formula (2-1), R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms. The alkyl group and aryl group Some or all of the hydrogen atoms contained in may be substituted, or any two or more of R ⁴ , R ⁵ and R ⁶ may be bonded to each other, and the ring structure together with the sulfur atom to which they are bonded May be formed.
In formula (2-2), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and aryl group may be substituted. R ⁷ and R ⁸ may be bonded to each other to form a ring structure together with the iodine atom to which they are bonded. ) The photoresist composition according to any one of claims 1 to 4, wherein the structural unit (I) 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 , R ¹¹ and R ¹² are each independently an alkyl group having 1 to 10 carbon atoms. Or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that R ¹¹ and R ¹² are bonded to each other, and the divalent alicyclic ring having 4 to 20 carbon atoms together with the carbon atom to which they are bonded. (Formula hydrocarbon groups may be formed) (1) A step of forming a resist film on a substrate using the photoresist composition according to any one of claims 1 to 5 ;
(2) A resist pattern forming method including a step of exposing the resist film through a photomask, and (3) a step of developing the exposed resist film. The acid generator containing the compound represented by following formula (1).

(In formula (1), R ¹ is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, provided that a part or all of the hydrogen atoms of the alicyclic hydrocarbon group are substituted. In addition, an aliphatic heterocyclic ring may be condensed to the carbocyclic ring of the alicyclic hydrocarbon group, X is **-(X ² -R ′) _n —X ¹ —. X ¹ is * —COO— or —O—, X ² is —COO— or —O—, and R ′ is a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. However, some or all of the hydrogen atoms of the alicyclic hydrocarbon group may be substituted, and an aliphatic heterocyclic ring is condensed to the carbocyclic ring of the alicyclic hydrocarbon group. which may be .n is 0 or 1 ** represents a site that binds to ^{R 1} * is .R ² showing a site that binds to ^{R 1} side is at least -CFR ³ -.. the side A divalent linear fluorinated hydrocarbon group having an even number of carbon atoms in which two fluorine atoms are bonded to a terminal carbon atom, R ³ is a fluorine atom , M ⁺ is a monovalent cation .)