JP7480728B2 - Resist material and pattern forming method - Google Patents

Description

The present invention relates to a resist material and a pattern formation method.

As LSIs become more highly integrated and faster, pattern rules are becoming finer at a rapid pace. In particular, the expansion of the logic memory market due to the spread of smartphones is driving miniaturization. The most advanced miniaturization technology is the mass production of 10 nm node devices using double patterning with ArF immersion lithography, and preparations are underway for mass production of 7 nm node devices using double patterning for the next generation. Extreme ultraviolet (EUV) lithography is being considered as a candidate for the next-generation 5 nm node.

While logic devices are becoming more miniaturized, flash memory devices have become devices with stacked gates known as 3D-NAND, and the capacity is increasing as the number of layers increases. As the number of layers increases, the hard masks used to process them become thicker, and the photoresist films also become thicker. Resist films for logic devices are becoming thinner, while resist films for 3D-NAND are becoming thicker.

As miniaturization progresses and approaches the diffraction limit of light, the contrast of light decreases. This decrease in contrast of light causes a decrease in the resolution of hole and trench patterns and a decrease in focus margin in positive resist films. Thickening the resist film would restore the film thickness of the resist film for previous generation devices, but a higher degree of dimensional uniformity (CDU) is required, which cannot be met by previous photoresist films. In order to prevent a decrease in the resolution of the resist pattern due to the decrease in contrast of light caused by smaller dimensions, or to improve the CDU when thickening the resist film, attempts are being made to improve the dissolution contrast of the resist film.

For chemically amplified positive resist materials, which contain an acid generator and generate acid by irradiation with light or an electron beam (EB) to cause an acid-induced deprotection reaction, and for chemically amplified negative resist materials, which cause an acid-induced polarity change reaction or crosslinking reaction, the addition of a quencher to control the diffusion of acid into unexposed areas and improve contrast has been extremely effective. For this reason, many amine quenchers have been proposed (Patent Documents 1 and 2).

Amine quenchers with polarity change due to acid catalyst have been proposed. Patent Document 3 proposes an amine quencher with an acid labile group. In this case, a tertiary ester with a carbonyl group on the nitrogen atom side is deprotected by an acid to generate a carboxylic acid, which improves alkali solubility. However, in this case, the molecular weight on the nitrogen atom side cannot be increased, so the acid diffusion control ability is low and the effect of improving contrast is slight. Patent Document 4 proposes a quencher in which an amino group is generated by a deprotection reaction of a tert-butoxycarbonyl group by an acid. This is a mechanism in which a quencher is generated by exposure to light, which has the opposite effect to increasing contrast. The contrast is improved by a mechanism in which the quencher disappears or the quenching ability is reduced by exposure to light or acid. Patent Document 5 proposes a quencher in which an amine compound forms a ring with an acid to form a lactam structure. The activity of the acid changes as a strong base amine compound changes to a weak base lactam compound, improving contrast.

The acid labile groups used in (meth)acrylate polymers for ArF resist materials undergo deprotection reaction using a photoacid generator that generates sulfonic acid substituted with a fluorine atom at the α-position, but the deprotection reaction does not proceed with an acid generator that generates sulfonic acid or carboxylic acid not substituted with a fluorine atom at the α-position. When a sulfonium salt or iodonium salt that generates a sulfonic acid not substituted with a fluorine atom at the α-position is mixed with a sulfonium salt or iodonium salt that generates a sulfonic acid not substituted with a fluorine atom at the α-position, the sulfonium salt or iodonium salt that generates a sulfonic acid not substituted with a fluorine atom at the α-position undergoes ion exchange with the sulfonic acid not substituted with a fluorine atom at the α-position. The sulfonic acid substituted with a fluorine atom at the α-position generated by light is reverted to a sulfonium salt or iodonium salt by ion exchange, so the sulfonium salt or iodonium salt of the sulfonic acid or carboxylic acid not substituted with a fluorine atom at the α-position functions as a quencher. A resist material has been proposed that uses a sulfonium salt or an iodonium salt that generates a carboxylic acid as a quencher (Patent Document 6).

Sulfonium salt-type quenchers and iodonium salt-type quenchers are photodegradable, just like photoacid generators. In other words, the amount of quencher is reduced in the exposed areas. Since acid is generated in the exposed areas, when the amount of quencher is reduced, the acid concentration becomes relatively higher, which improves contrast. However, acid diffusion in the exposed areas cannot be suppressed, making it difficult to control acid diffusion.

Sulfonium salt type quenchers and iodonium salt type quenchers absorb light with a wavelength of 193 nm, so when used in combination with a sulfonium salt type or iodonium salt type acid generator, the transmittance of the light through the resist film decreases. As a result, the cross-sectional shape of the pattern after development becomes tapered, especially in resist films with a thickness of 100 nm or more. A highly transparent quencher is required for resist films with a thickness of 100 nm or more, especially 150 nm or more.

In order to suppress the diffusion of acid, it is effective to lower the post-exposure bake (PEB) temperature. However, in this case, the dissolution contrast decreases, which causes degradation of the resolution and line edge roughness (LWR). There is a demand for a new concept resist material that suppresses the diffusion of acid and exhibits high contrast.

JP 2001-194776 A JP 2007-108451 A JP 2002-363148 A JP 2001-166476 A JP 2012-137729 A International Publication No. 2008/066011

In chemically amplified resist materials that use acid as a catalyst, there is a need to develop a quencher that can reduce the LWR of line patterns and the CDU of hole patterns while also improving sensitivity. This requires further reducing the diffusion distance of the acid and simultaneously improving the contrast, which are two opposing properties.

The present invention has been made in consideration of the above circumstances, and aims to provide a resist material that is highly sensitive and has small LWR and CDU, whether positive or negative, and a pattern formation method using the same.

As a result of extensive research into achieving the above object, the inventors discovered that by using a cyclic ammonium salt having a saturated hydrocarbyl group or aryl group substituted with a fluorine atom (hereinafter also referred to as a fluorine atom-containing cyclic ammonium salt compound) as a quencher, it is possible to obtain a resist material with small LWR and CDU, high contrast, excellent resolution, and a wide process margin, and thus completed the present invention.

（式中、環Ｒは、式中の窒素原子と共に形成される炭素数２～１２の脂環基であり、該環の中に、エーテル結合、チオエーテル結合、カルボニル基、－Ｎ(Ｒ')－又はスルホニル基を含んでいてもよい。Ｒ'は、水素原子、炭素数１～６の飽和ヒドロカルビル基又は－Ｌ³－Ｒ³である。
Ｌ¹、Ｌ²及びＬ³は、それぞれ独立に、単結合、エステル結合、スルホニル基又は炭素数１～６のアルカンジイル基であり、該アルカンジイル基の水素原子の一部がヒドロキシ基、フッ素原子で置換されていてもよい炭素数１～１２のヒドロカルビルオキシ基、又はフッ素原子で置換されていてもよい炭素数２～１２のヒドロカルビルカルボニルオキシ基で置換されていてもよく、該アルカンジイル基を構成するメチレン基の一部がエーテル結合、エステル結合、アミド結合、スルホニル基、スルホン酸エステル結合又はスルホンアミド結合で置換されていてもよい。ただし、Ｌ¹、Ｌ²及びＬ³は、第３級エステル構造は含まない。
Ｒ¹、Ｒ²及びＲ³は、それぞれ独立に、水素原子、炭素数１～１６の飽和ヒドロカルビル基、炭素数６～１０のアリール基、少なくとも３つのフッ素原子で置換された炭素数１～１６の飽和ヒドロカルビル基、少なくとも３つのフッ素原子で置換された炭素数６～１０のアリール基、又はこれらを組み合わせて得られる基であり、Ｒ¹及びＲ²の一方又は両方は、少なくとも３つのフッ素原子を有する。
Ｘ^-は、カルボン酸アニオン、スルホンアミドアニオン、ハロゲン化フェノキシドアニオン又はハロゲン化物アニオンである。）
２．Ｘ^-が、ヨウ素原子若しくは臭素原子を含むカルボン酸アニオン、ヨウ素原子若しくは臭素原子を含むスルホンアミドアニオン、又はヨウ素原子若しくは臭素原子を含むフェノキシドアニオンである１のレジスト材料。
３．更に、スルホン酸、イミド酸又はメチド酸を発生する酸発生剤を含む１又は２のレジスト材料。
４．更に、有機溶剤を含む１～３のいずれかのレジスト材料。
５．前記ベースポリマーが、下記式（ａ１）で表される繰り返し単位又は下記式（ａ２）で表される繰り返し単位を含むものである１～４のいずれかのレジスト材料。

（式中、Ｒ^Aは、それぞれ独立に、水素原子又はメチル基である。
Ｙ¹は、単結合、フェニレン基若しくはナフチレン基、又はエステル結合若しくはラクトン環から選ばれる少なくとも１種を含む炭素数１～１２の連結基である。
Ｙ²は、単結合又はエステル結合である。
Ｙ³は、単結合、エーテル結合又はエステル結合である。
Ｒ¹¹及びＲ¹²は、それぞれ独立に、酸不安定基である。
Ｒ¹³は、フッ素原子、トリフルオロメチル基、シアノ基又は炭素数１～６の飽和ヒドロカルビル基である。
Ｒ¹⁴は、単結合又は炭素数１～６のアルカンジイル基であり、その炭素原子の一部がエーテル結合又はエステル結合で置換されていてもよい。
ａは、１又は２である。ｂは、０～４の整数である。ただし、１≦ａ＋ｂ≦５である。）
６．化学増幅ポジ型レジスト材料である５のレジスト材料。
７．前記ベースポリマーが、酸不安定基を含まないものである１～４のいずれかのレジスト材料。
８．化学増幅ネガ型レジスト材料である７のレジスト材料。
９．更に、界面活性剤を含む１～８のいずれかのレジスト材料。
１０．前記ベースポリマーが、更に、下記式（ｆ１）～（ｆ３）で表される繰り返し単位から選ばれる少なくとも１種を含む１～９のいずれかのレジスト材料。

（式中、Ｒ^Aは、それぞれ独立に、水素原子又はメチル基である。
Ｚ¹は、単結合、炭素数１～６の脂肪族ヒドロカルビレン基、フェニレン基、ナフチレン基若しくはこれらを組み合わせて得られる炭素数７～１８の基、又は－Ｏ－Ｚ¹¹－、－Ｃ(＝Ｏ)－Ｏ－Ｚ¹¹－若しくは－Ｃ(＝Ｏ)－ＮＨ－Ｚ¹¹－である。Ｚ¹¹は、炭素数１～６の脂肪族ヒドロカルビレン基、フェニレン基、ナフチレン基又はこれらを組み合わせて得られる炭素数７～１８の基であり、カルボニル基、エステル結合、エーテル結合又はヒドロキシ基を含んでいてもよい。
Ｚ²は、単結合又はエステル結合である。
Ｚ³は、単結合、－Ｚ³¹－Ｃ(＝Ｏ)－Ｏ－、－Ｚ³¹－Ｏ－又は－Ｚ³¹－Ｏ－Ｃ(＝Ｏ)－である。Ｚ³¹は、炭素数１～１２のヒドロカルビレン基、フェニレン基又はこれらを組み合わせて得られる炭素数７～１８の基であり、カルボニル基、エステル結合、エーテル結合、ヨウ素原子又は臭素原子を含んでいてもよい。
Ｚ⁴は、メチレン基、２,２,２－トリフルオロ－１,１－エタンジイル基又はカルボニル基である。
Ｚ⁵は、単結合、メチレン基、エチレン基、フェニレン基、フッ素化フェニレン基、トリフルオロメチル基で置換されたフェニレン基、－Ｏ－Ｚ⁵¹－、－Ｃ(＝Ｏ)－Ｏ－Ｚ⁵¹－又は－Ｃ(＝Ｏ)－ＮＨ－Ｚ⁵¹－である。Ｚ⁵¹は、炭素数１～６の脂肪族ヒドロカルビレン基、フェニレン基、フッ素化フェニレン基又はトリフルオロメチル基で置換されたフェニレン基であり、カルボニル基、エステル結合、エーテル結合又はヒドロキシ基を含んでいてもよい。
Ｒ²¹～Ｒ²⁸は、それぞれ独立に、ハロゲン原子、又はヘテロ原子を含んでいてもよい炭素数１～２０のヒドロカルビル基である。また、Ｒ²³とＲ²⁴と又はＲ²⁶とＲ²⁷とが、互いに結合してこれらが結合する硫黄原子と共に環を形成していてもよい。
Ｍ^-は、非求核性対向イオンである。）
１１．１～１０のいずれかのレジスト材料を用いて基板上にレジスト膜を形成する工程と、前記レジスト膜を高エネルギー線で露光する工程と、前記露光したレジスト膜を、現像液を用いて現像する工程とを含むパターン形成方法。
１２．前記高エネルギー線が、波長３６５ｎｍのｉ線、波長１９３ｎｍのＡｒＦエキシマレーザー光又は波長２４８ｎｍのＫｒＦエキシマレーザー光である１１のパターン形成方法。
１３．前記高エネルギー線が、ＥＢ又は波長３～１５ｎｍのＥＵＶである１１のパターン形成方法。
１４．下記式（Ａ'）で表される塩化合物

（式中、Ｒ、Ｌ¹、Ｌ²、Ｒ¹及びＲ²は、前記と同じ。
Ｒ⁴は、単結合又はカルボニル基である。
Ｒ⁵は、水素原子、ヒドロキシ基、ハロゲン原子で置換されていてもよい炭素数１～６の飽和ヒドロカルビル基、ハロゲン原子で置換されていてもよい炭素数１～６の飽和ヒドロカルビルオキシ基、ハロゲン原子で置換されていてもよい炭素数２～７の飽和ヒドロカルビルカルボニルオキシ基、ハロゲン原子で置換されていてもよい炭素数１～４の飽和ヒドロカルビルスルホニルオキシ基、フッ素原子、塩素原子、臭素原子、アミノ基、ニトロ基、シアノ基、－Ｎ(Ｒ⁵¹)－Ｃ(＝Ｏ)－Ｒ⁵²又は－Ｎ(Ｒ⁵¹)－Ｃ(＝Ｏ)－Ｏ－Ｒ⁵²である。Ｒ⁵¹は、水素原子又は炭素数１～６の飽和ヒドロカルビル基である。Ｒ⁵²は、炭素数１～６の飽和ヒドロカルビル基又は炭素数２～８の不飽和脂肪族ヒドロカルビル基である。
ｓ及びｔは、１≦ｓ≦５、０≦ｔ≦３及び１≦ｓ＋ｔ≦５を満たす整数である。） That is, the present invention provides the following resist material and pattern forming method.
1. A resist material comprising a base polymer and a quencher comprising a salt compound represented by the following formula (A):

(In the formula, ring R is an alicyclic group having 2 to 12 carbon atoms formed together with the nitrogen atom in the formula, and the ring may contain an ether bond, a thioether bond, a carbonyl group, -N(R')- or a sulfonyl group. R' is a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms or ^-L3 - ^R3 .
L ¹ , L ² and L ³ are each independently a single bond, an ester bond, a sulfonyl group or an alkanediyl group having 1 to 6 carbon atoms, some of the hydrogen atoms of the alkanediyl group may be substituted with a hydroxy group, a hydrocarbyloxy group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, or a hydrocarbylcarbonyloxy group having 2 to 12 carbon atoms which may be substituted with a fluorine atom, and some of the methylene groups constituting the alkanediyl group may be substituted with an ether bond, an ester bond, an amide bond, a sulfonyl group, a sulfonate ester bond or a sulfonamide bond, provided that L ¹ , L ² and L ³ do not include a tertiary ester structure.
R ¹ , R ² and R ³ each independently represent a hydrogen atom, a saturated hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 10 carbon atoms, a saturated hydrocarbyl group having 1 to 16 carbon atoms and substituted with at least three fluorine atoms, an aryl group having 6 to 10 carbon atoms and substituted with at least three fluorine atoms, or a group obtained by combining these, and one or both of R ¹ and R ² have at least three fluorine atoms.
X ⁻ is a carboxylate anion, a sulfonamide anion, a halogenated phenoxide anion, or a halide anion.
2. The resist material of 1, wherein X ⁻ is a carboxylate anion containing an iodine atom or a bromine atom, a sulfonamide anion containing an iodine atom or a bromine atom, or a phenoxide anion containing an iodine atom or a bromine atom.
3. The resist material according to 1 or 2, further comprising an acid generator that generates a sulfonic acid, an imide acid or a methide acid.
4. The resist material according to any one of 1 to 3, further comprising an organic solvent.
5. The resist material according to any one of 1 to 4, wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2):

(In the formula, each R ^A is independently a hydrogen atom or a methyl group.
Y ¹ is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring.
^Y2 is a single bond or an ester bond.
^Y3 is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are each independently an acid labile group.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group or a saturated hydrocarbyl group having 1 to 6 carbon atoms.
R ¹⁴ is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with ether bonds or ester bonds.
a is 1 or 2. b is an integer from 0 to 4, provided that 1≦a+b≦5.
6. The resist material of 5, which is a chemically amplified positive resist material.
7. The resist material according to any one of 1 to 4, wherein the base polymer does not contain an acid labile group.
8. The resist material of 7, which is a chemically amplified negative resist material.
9. The resist material according to any one of 1 to 8, further comprising a surfactant.
10. The resist material of any one of 1 to 9, wherein the base polymer further contains at least one repeating unit selected from those represented by the following formulas (f1) to (f3):

(In the formula, each R ^A is independently a hydrogen atom or a methyl group.
Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ¹¹ -, -C(═O)-O-Z ¹¹ -, or -C(═O)-NH-Z ¹¹ -. ^{Z 11} is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.
^Z2 is a single bond or an ester bond.
Z ³¹ is a single bond, -Z ³¹ -C(═O)-O-, -Z ³¹ -O-, or -Z ³¹ -O-C(═O)-. Z ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom.
^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group or a carbonyl group.
^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- or -C(=O)-NH- ^Z51- . ^Z51 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group.
R ²¹ to R ²⁸ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R ²³ and R ²⁴ , or R ²⁶ and R ²⁷ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
M ⁻ is a non-nucleophilic counter ion.
11. A pattern forming method comprising the steps of forming a resist film on a substrate using a resist material according to any one of claims 1 to 10, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.
12. The pattern formation method according to 11, wherein the high-energy radiation is i-rays having a wavelength of 365 nm, ArF excimer laser light having a wavelength of 193 nm, or KrF excimer laser light having a wavelength of 248 nm.
13. The pattern formation method according to 11, wherein the high energy radiation is EB or EUV having a wavelength of 3 to 15 nm.
14. A salt compound represented by the following formula (A'):

(In the formula, R, L ¹ , L ² , R ¹ and R ² are the same as defined above.
^R4 is a single bond or a carbonyl group.
R ⁵ is a hydrogen atom, a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms which may be substituted with a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, -N(R ⁵¹ )-C(═O)-R ⁵² , or -N(R ⁵¹ )-C(═O)-O-R ^52. R ⁵¹ is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ⁵² is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.
s and t are integers satisfying 1≦s≦5, 0≦t≦3, and 1≦s+t≦5.

The fluorine-containing cyclic ammonium salt compound is a quencher that suppresses acid diffusion. The fluorine-containing cyclic ammonium salt compound has a saturated hydrocarbyl group substituted with a fluorine atom or an aryl group substituted with a fluorine atom, so that the quenchers do not aggregate due to the electrical repulsion of the fluorine atoms, and are uniformly dispersed in the resist film. Furthermore, when the anion contains an iodine atom or a bromine atom, the absorption of the exposure light is large, so that the sensitivity is improved and the acid diffusion characteristics are low, making it possible to reduce the LWR and CDU. These make it possible to construct a resist material that is highly sensitive and has improved LWR and CDU.

1 is a ¹ H-NMR spectrum of the quencher Q-1 obtained in Synthesis Example 1-1.

[Resist Material]
The resist material of the present invention comprises a base polymer and a quencher comprising a fluorine atom-containing cyclic ammonium salt compound.

[Fluorine atom-containing cyclic ammonium salt compound]
The fluorine atom-containing cyclic ammonium salt compound is represented by the following formula (A).

In formula (A), ring R is an alicyclic group having 2 to 12 carbon atoms formed together with the nitrogen atom in the formula, and the ring may contain an ether bond, a thioether bond, a carbonyl group, -N(R')- or a sulfonyl group. R' is a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, or -L ³ -R ^3. Examples of the saturated hydrocarbyl group having 1 to 6 carbon atoms include those having 1 to 6 carbon atoms among the examples of saturated hydrocarbyl groups having 1 to 16 carbon atoms represented by R ¹ to R ³ described below.

The alicyclic group may be a structure in which one carbon atom of a cyclic saturated hydrocarbon having 3 to 13 carbon atoms is replaced with a nitrogen atom, and some of the other carbon atoms may be replaced with an ether bond, a thioether bond, a carbonyl group, -N(R')-, or a sulfonyl group. Examples of the cyclic saturated hydrocarbon include cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, and adamantane.

In formula (A), L ¹ , L ² and L ³ are each independently a single bond, an ester bond, a sulfonyl group or an alkanediyl group having 1 to 6 carbon atoms, some of the hydrogen atoms of the alkanediyl group may be substituted with a hydroxy group, a hydrocarbyloxy group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, or a hydrocarbylcarbonyloxy group having 2 to 12 carbon atoms which may be substituted with a fluorine atom, and some of the methylene groups constituting the alkanediyl group may be substituted with an ether bond, an ester bond, an amide bond, a sulfonyl group, a sulfonate ester bond or a sulfonamide bond, provided that L ¹ , L ² and L ³ do not include a tertiary ester structure.

Examples of the alkanediyl group having 1 to 6 carbon atoms represented by L ¹ , L ² , and L ³ include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group.

The hydrocarbyl moiety of the hydrocarbyloxy group having 1 to 12 carbon atoms, which may be substituted with a fluorine atom, and the hydrocarbylcarbonyloxy group having 2 to 12 carbon atoms, which may be substituted with a fluorine atom, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the hydrocarbyl moiety include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, and dodecyl; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and a Examples include cyclic saturated hydrocarbyl groups having 3 to 12 carbon atoms, such as a damantyl group; alkenyl groups having 2 to 12 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, a pentenyl group, and a hexenyl group; aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, a diethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, and a naphthyl group; aralkyl groups having 7 to 12 carbon atoms, such as a benzyl group and a phenethyl group; and groups obtained by combining these groups.

In formula (A), R ¹ , R ² and R ³ each independently represent a hydrogen atom, a saturated hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 10 carbon atoms, a saturated hydrocarbyl group having 1 to 16 carbon atoms and substituted with at least three fluorine atoms, an aryl group having 6 to 10 carbon atoms and substituted with at least three fluorine atoms, or a group obtained by combining these, and one or both of R ¹ and R ² have at least three fluorine atoms.

The saturated hydrocarbyl group having 1 to 16 carbon atoms represented by R ¹ , R ² , and R ³ may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 16 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, and pentadecyl groups; cyclic saturated hydrocarbyl groups having 3 to 16 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; and groups obtained by combining these. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, a diethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, and a naphthyl group.

Examples of the cation of the salt compound represented by formula (A) include, but are not limited to, those shown below.

In formula (A), X ⁻ is a carboxylate anion, a sulfonamide anion, a halogenated phenoxide anion or a halide anion.

The carboxylate anion is preferably one represented by the following formula (Aa): The sulfonamide anion is preferably one represented by the following formula (Ab): The halogenated phenoxide anion is preferably one represented by the following formula (Ac):

In formula (Aa), R ^a1 is a hydrogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 30 carbon atoms, a cyclic saturated hydrocarbyl group having 3 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, a cyclic unsaturated aliphatic hydrocarbyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, and groups obtained by combining these groups. In addition, a portion of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and a portion of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, so that the group may contain an ester bond, an ether bond, a thioether bond, a carbonyl group, a sulfonyl group, a carbonate group, a carbamate group, a sulfone group, an amino group, an amide bond, a hydroxyl group, a thiol group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or the like.

In formula (Ab), R ^b1 is a fluorine atom, a hydrocarbyl group having 1 to 10 carbon atoms, or a fluorinated hydrocarbyl group having 1 to 10 carbon atoms, and the hydrocarbyl group or fluorinated hydrocarbyl group may contain a hydroxy group, a carboxy group, an ether bond, an ester bond, or an amide bond. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 10 carbon atoms, a cyclic saturated hydrocarbyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cyclic unsaturated aliphatic hydrocarbyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and groups obtained by combining these groups. In addition, the fluorinated hydrocarbyl group may be a group in which some or all of the hydrogen atoms of the hydrocarbyl group are substituted with fluorine atoms.

In formula (Ab), R ^b2 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R ^b1 and R ^b2 may be bonded to each other to form a ring together with the atom to which they are bonded. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, a cyclic unsaturated aliphatic hydrocarbyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, and groups obtained by combining these groups. In addition, a portion of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and a portion of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, so that the group may contain an ester bond, an ether bond, a thioether bond, a carbonyl group, a sulfonyl group, a carbonate group, a carbamate group, a sulfone group, an amino group, an amide bond, a hydroxyl group, a thiol group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or the like.

In formula (Ac), R ^c1 is a fluorine atom, a trifluoromethyl group, a 1,1,1,3,3,3-hexafluoro-2-propanol group, a chlorine atom, a bromine atom or an iodine atom. Of these, R ^c1 is preferably a fluorine atom, a bromine atom or an iodine atom.

In formula (Ac), R ^c2 is a hydrogen atom, a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms which may be substituted with a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, -N(R ^c21 )-C(═O)-R ^c22 , or -N(R ^c21 )-C(═O)-O-R ^c22 . R ^c21 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^c22 is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. m and n are integers which satisfy 1≦m≦5, 0≦n≦3, and 1≦m+n≦5.

The saturated hydrocarbyl group having 1 to 6 carbon atoms represented by R ^c2 , R ^c21 and R ^c22 may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups; and groups obtained by combining these groups. In addition, examples of the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms and the saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms include the same as the saturated hydrocarbyl group described above. In addition, examples of the saturated hydrocarbyl moiety of the saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms include the saturated hydrocarbyl groups described above having 1 to 4 carbon atoms.

The unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms represented by ^R may be linear, branched, or cyclic. Specific examples thereof include alkenyl groups such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group, and a hexenyl group; and cyclic unsaturated aliphatic hydrocarbyl groups such as a cyclohexenyl group.

Of these, preferred R ^c2 are a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an acyloxy group having 2 to 4 carbon atoms, -N(R ^c21 )-C(=O)-R ^c22 or -N(R ^c21 )-C(=O)-O-R ^c22 .

Examples of the carboxylate anion include, but are not limited to, those shown below.

The sulfonamide anions include, but are not limited to, those shown below.

Examples of the halogenated phenoxide anions include, but are not limited to, those shown below.

Examples of the halide anion include fluoride ion, chloride ion, bromide ion, iodide ion, etc.

Among these anions, carboxylate anions containing iodine or bromine atoms, sulfonamide anions containing iodine or bromine atoms, and phenoxide anions containing iodine or bromine atoms are preferred because they have high EUV absorption and are highly effective in improving sensitivity through the generation of secondary electrons.

As the salt compound represented by formula (A), particularly preferred is one containing a carboxylate anion containing an iodine atom or a phenoxide anion containing an iodine atom represented by the following formula (A').

In formula (A'), R, L ¹ , L ² , R ¹ and R ² are the same as above. R ⁴ is a single bond or a carbonyl group. R ⁵ is a hydrogen atom, a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms which may be substituted with a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, -N(R ⁵¹ )-C(═O)-R ⁵² or -N(R ⁵¹ )-C(═O)-O-R ^52. R ⁵¹ is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ⁵² is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. s and t are integers satisfying 1≦s≦5, 0≦t≦3 and 1≦s+t≦5. Specific examples of the groups represented by R ⁵ , R ⁵¹ and R ⁵² include the same as those exemplified as specific examples of the groups represented by R ^c2 , R ^c21 and R ^c22 in the explanation of formula (Ac).

The fluorine-containing cyclic ammonium salt compound can be synthesized, for example, by a neutralization reaction between a fluorine-containing cyclic amine compound having a structure in which a hydrogen atom on the quaternary nitrogen atom of the cation of the fluorine-containing cyclic ammonium salt compound is eliminated, and a carboxylic acid compound, a sulfonamide compound, a halogenated phenol compound, or a hydrogen halide compound. The neutralization reaction is preferably carried out in an amount such that the ratio of the amount of substance (molar ratio) of the amino group of the fluorine-containing cyclic amine compound to the carboxylic acid compound, the sulfonamide compound, the halogenated phenol compound, or the hydrogen halide compound is 1:1, but either one may be in excess. The fluorine-containing cyclic amine compound can be synthesized, for example, according to the method described in JP-A-2007-108451.

The fluorine atom-containing cyclic ammonium salt compound has three or more fluorine atoms on the cation side. The electrical repulsion of the fluorine atoms prevents the quenchers from agglomerating together, which makes acid diffusion uniform at the nanometer level. This improves the LWR and CDU of the resist pattern after development.

In the resist material of the present invention, the content of the fluorine atom-containing cyclic ammonium salt compound is preferably 0.001 to 50 parts by mass, more preferably 0.01 to 40 parts by mass, per 100 parts by mass of the base polymer described below, from the viewpoints of sensitivity and acid diffusion suppression effect. The fluorine atom-containing cyclic ammonium salt compound may be used alone or in combination of two or more kinds.

[Base polymer]
In the case of a positive resist material, the base polymer contained in the resist material of the present invention contains a repeating unit having an acid labile group. The repeating unit having an acid labile group is preferably a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2).

In formulae (a1) and (a2), R ^A is independently a hydrogen atom or a methyl group. Y ¹ is a linking group having 1 to 12 carbon atoms containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, or a lactone ring. Y ² is a single bond or an ester bond. Y ³ is a single bond, an ether bond, or an ester bond. R ¹¹ and R ¹² are independently an acid labile group. In addition, when the base polymer contains both the repeating unit a1 and the repeating unit a2, R ¹¹ and R ¹² may be the same or different from each other. R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ¹⁴ is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. However, 1≦a+b≦5.

Examples of monomers that provide the repeating unit a1 include, but are not limited to, those shown below: In the following formula, R ^A and R ¹¹ are the same as defined above.

Examples of monomers that provide the repeating unit a2 include, but are not limited to, those shown below: In the following formula, R ^A and R ¹² are the same as defined above.

In formulae (a1) and (a2), examples of the acid labile group represented by R ¹¹ and R ¹² include those described in JP-A-2013-80033 and JP-A-2013-83821.

（式中、破線は、結合手である。） Typically, the acid labile group includes those represented by the following formulae (AL-1) to (AL-3).

(In the formula, the dashed lines represent bonds.)

In formulae (AL-1) and (AL-2), R ^L1 and R ^L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. As the hydrocarbyl group, a saturated hydrocarbyl group having 1 to 40 carbon atoms is preferred, and a saturated hydrocarbyl group having 1 to 20 carbon atoms is more preferred.

In formula (AL-1), c is an integer from 0 to 10, preferably an integer from 1 to 5.

In formula (AL-2), R ^L3 and R ^L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. Any two of R ^L2 , R ^L3 , and R ^L4 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded, or a carbon atom and an oxygen atom. The ring is preferably a ring having 4 to 16 carbon atoms, and particularly preferably an alicyclic ring.

In formula (AL-3), R ^L5 , R ^L6 and R ^L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. Any two of R ^L5 , R ^L6 and R ^L7 may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. The ring is preferably a ring having 4 to 16 carbon atoms, and particularly preferably an alicyclic ring.

The base polymer may contain a repeating unit b containing a phenolic hydroxyl group as an adhesive group. Examples of monomers that provide the repeating unit b include, but are not limited to, the following. In the following formula, R ^A is the same as above.

The base polymer may contain a repeating unit c containing a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group as another adhesive group. Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. In the following formula, R ^A is the same as above.

The base polymer may include repeat units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Monomers that provide repeat units d include, but are not limited to, those shown below.

The base polymer may contain a repeating unit e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindane, vinylpyridine, or vinylcarbazole.

The base polymer may contain a repeating unit f derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units f include a repeating unit represented by the following formula (f1) (hereinafter also referred to as repeating unit f1), a repeating unit represented by the following formula (f2) (hereinafter also referred to as repeating unit f2), and a repeating unit represented by the following formula (f3) (hereinafter also referred to as repeating unit f3). The repeating units f1 to f3 may be used alone or in combination of two or more.

In formulae (f1) to (f3), R ^A is each independently a hydrogen atom or a methyl group. Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ¹¹ -, -C(═O)-O-Z ¹¹ -, or -C(═O)-NH-Z ¹¹ -. Z ¹¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z ² is a single bond or an ester bond. Z ³ is a single bond, -Z ³¹ -C(═O)-O-, -Z ³¹ -O-, or -Z ³¹ -O-C(═O)-. Z ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z ⁴ is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ^{Z 5} is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O-Z ⁵¹ -, -C(═O)-O-Z ⁵¹ -, or -C(═O)-NH-Z ⁵¹ -. ^{Z 51} is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.

In formulas (f1) to (f3), R ²¹ to R ²⁸ are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those exemplified in the description of R ¹⁰¹ to R ¹⁰⁵ in formulas (1-1) and (1-2) described later. The hydrocarbyl group may have some or all of its hydrogen atoms substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like. In addition, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring include the same as those exemplified as the ring that can be formed by R ¹⁰¹ and R ¹⁰² bonded to each other together with the sulfur atom to which they are bonded in the description of formula (1-1) below.

In formula (f1), M ⁻ is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

Other examples of the non-nucleophilic counter ion include a sulfonate ion represented by the following formula (f1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate ion represented by the following formula (f1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group.

In formula (f1-1), R ³¹ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same as those described below as the hydrocarbyl group represented by R ¹¹¹ in formula (1A').

In formula (f1-2), R ³² is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 6 to 20 carbon atoms, and the hydrocarbyl group and the hydrocarbylcarbonyl group may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl group and the hydrocarbylcarbonyl group may have a hydrocarbyl moiety that is saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include the same as those described below as the hydrocarbyl group represented by R ¹¹¹ in formula (1A').

Examples of the cation of the monomer that gives the repeating unit f1 include, but are not limited to, those shown below: In the following formula, R ^A is the same as defined above.

Cations of the monomers that give the repeating units f2 and f3 include the same as those exemplified as the cations of the sulfonium salts represented by formula (1-1) described below.

Examples of the anion of the monomer that gives the repeating unit f2 include, but are not limited to, those shown below: In the following formula, R ^A is the same as defined above.

Examples of the anion of the monomer that gives the repeating unit f3 include, but are not limited to, those shown below: In the following formula, R ^A is the same as defined above.

By binding the acid generator to the polymer main chain, acid diffusion is reduced, and a decrease in resolution due to blurring caused by acid diffusion can be prevented. Furthermore, uniform dispersion of the acid generator improves LWR and CDU. Note that when using a base polymer containing repeating unit f (i.e., a polymer-bound acid generator), the incorporation of an additive acid generator, described below, can be omitted.

The base polymer for a positive resist material must contain a repeating unit a1 or a2 that contains an acid labile group. In this case, the content ratios of the repeating units a1, a2, b, c, d, e, and f are preferably 0≦a1<1.0, 0≦a2<1.0, 0<a1+a2<1.0, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.8, 0≦e≦0.8, and 0≦f≦0.5, more preferably 0≦a1≦0.9, 0≦a2≦0.9, 0.1≦a1+a2≦0.9, 0≦b≦0.8, 0≦c≦0.8, 0≦d≦0.7, 0≦e≦0.7, and 0≦f≦0.4, and further preferably 0≦a1≦0.8, 0≦a2≦0.8, 0.1≦a1+a2≦0.8, 0≦b≦0.75, 0≦c≦0.75, 0≦d≦0.6, 0≦e≦0.6, and 0≦f≦0.3. In addition, when the repeating unit f is at least one selected from repeating units f1 to f3, f = f1 + f2 + f3. Also, a1 + a2 + b + c + d + e + f = 1.0.

On the other hand, the base polymer for a negative resist material does not necessarily need to have an acid labile group. Examples of such base polymers include those that contain repeating unit b and, if necessary, further contain repeating units c, d, e and/or f. The content ratios of these repeating units are preferably 0<b≦1.0, 0≦c≦0.9, 0≦d≦0.8, 0≦e≦0.8 and 0≦f≦0.5, more preferably 0.2≦b≦1.0, 0≦c≦0.8, 0≦d≦0.7, 0≦e≦0.7 and 0≦f≦0.4, and even more preferably 0.3≦b≦1.0, 0≦c≦0.75, 0≦d≦0.6, 0≦e≦0.6 and 0≦f≦0.3. When the repeating unit f is at least one selected from the repeating units f1 to f3, f=f1+f2+f3. Also, b+c+d+e+f=1.0.

To synthesize the base polymer, for example, a monomer that provides the repeating units described above may be polymerized by heating in an organic solvent with the addition of a radical polymerization initiator.

Organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, dioxane, etc. Polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, etc. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

When copolymerizing monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups such as ethoxyethoxy groups, which are easily deprotected by acid, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxyl groups may be substituted with acetyl groups, formyl groups, pivaloyl groups, etc., and then hydrolyzed with an alkali after polymerization.

When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy groups may be deprotected by alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

Ammonia water, triethylamine, etc. can be used as the base for alkaline hydrolysis. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

The base polymer preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of 1,000 to 500,000, more preferably 2,000 to 30,000. If the Mw is within the above range, the resist film has good heat resistance and solubility in an alkaline developer.

In addition, if the base polymer has a wide molecular weight distribution (Mw/Mn), low and high molecular weight polymers may be present, which may result in foreign matter appearing on the pattern after exposure or deterioration of the pattern shape. As the pattern rules become finer, the effects of Mw and Mw/Mn tend to become greater. Therefore, in order to obtain a resist material suitable for fine pattern dimensions, it is preferable that the Mw/Mn of the base polymer has a narrow distribution of 1.0 to 2.0, and particularly 1.0 to 1.5.

The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw/Mn.

[Acid Generator]
The resist material of the present invention may contain an acid generator (hereinafter also referred to as an additive acid generator) that generates a strong acid. In the case of a chemically amplified positive resist material, the strong acid means a compound having sufficient acidity to cause a deprotection reaction of an acid labile group of a base polymer, and in the case of a chemically amplified negative resist material, it means a compound having sufficient acidity to cause a polarity change reaction or a crosslinking reaction by an acid. By containing such an acid generator, the fluorine atom-containing cyclic ammonium salt compound functions as a quencher, and the resist material of the present invention can function as a chemically amplified positive resist material or a chemically amplified negative resist material.

The acid generator may be, for example, a compound (photoacid generator) that generates an acid in response to actinic rays or radiation. The photoacid generator may be any compound that generates an acid when irradiated with high-energy rays, but is preferably one that generates a sulfonic acid, an imide acid, or a methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of photoacid generators include those described in paragraphs [0122] to [0142] of JP 2008-111103 A.

In addition, as the photoacid generator, a sulfonium salt represented by the following formula (1-1) or an iodonium salt represented by the following formula (1-2) can also be suitably used.

In formulae (1-1) and (1-2), R ¹⁰¹ to R ¹⁰⁵ each independently represent a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

The hydrocarbyl groups having 1 to 20 carbon atoms represented by R ¹⁰¹ to R ¹⁰⁵ may be saturated or unsaturated, and may be straight-chain, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups, such as vinyl, propenyl, butenyl, and hexenyl groups; ethynyl, propyl, alkynyl groups having 2 to 20 carbon atoms, such as a cyclohexenyl group and a norbornenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group and a norbornenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a methylphenyl group, an ethylphenyl group, a n-propylphenyl group, an isopropylphenyl group, a n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, a n-propylnaphthyl group, an isopropylnaphthyl group, a n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group and a tert-butylnaphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group and a phenethyl group; and groups obtained by combining these.

In addition, some or all of the hydrogen atoms of these groups may be replaced with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be replaced with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the group containing a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like.

（式中、破線は、Ｒ¹⁰³との結合手である。） Furthermore, R ¹⁰¹ and R ¹⁰² may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is preferably one having the structure shown below.

(In the formula, the dashed line represents a bond to R ^103. )

Examples of the cation of the sulfonium salt represented by formula (1-1) include, but are not limited to, those shown below.

Examples of the cation of the iodonium salt represented by formula (1-2) include, but are not limited to, those shown below.

In formulas (1-1) and (1-2), Xa ⁻ is an anion selected from the following formulas (1A) to (1D).

In formula (1A), R ^fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A') described below.

The anion represented by formula (1A) is preferably an anion represented by the following formula (1A').

In formula (1A'), R ^HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ¹¹¹ is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, more preferably an oxygen atom. In order to obtain high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

The hydrocarbyl group represented by R ¹¹¹ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 38 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosanyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, Examples of the alkyl group include cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms, such as norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms, such as phenyl group, 1-naphthyl group, and 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these groups.

In addition, some or all of the hydrogen atoms of these groups may be replaced with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be replaced with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the group containing hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, and the like. Examples of hydrocarbyl groups containing heteroatoms include tetrahydrofuryl groups, methoxymethyl groups, ethoxymethyl groups, methylthiomethyl groups, acetamidomethyl groups, trifluoroethyl groups, (2-methoxyethoxy)methyl groups, acetoxymethyl groups, 2-carboxy-1-cyclohexyl groups, 2-oxopropyl groups, 4-oxo-1-adamantyl groups, and 3-oxocyclohexyl groups.

For the synthesis of sulfonium salts containing the anion represented by formula (1A'), see JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, etc., for details. In addition, sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644, etc. are also preferably used.

Examples of the anion represented by formula (1A) include, but are not limited to, those shown below: In the following formula, Ac is an acetyl group.

In formula (1B), R ^fb1 and R ^fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A'). R ^fb1 and R ^fb2 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. R ^fb1 and R ^fb2 may be bonded to each other to form a ring together with the group to which they are bonded (-CF ₂ -SO ₂ -N ^- -SO ₂ -CF ₂ -), and in this case, the group obtained by bonding R ^fb1 and R ^fb2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

In formula (1C), R ^fc1 , R ^fc2 and R ^fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A'). R ^fc1 , R ^fc2 and R ^fc3 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. R ^fc1 and R ^fc2 may be bonded to each other to form a ring together with the group (-CF ₂ -SO ₂ -C ^- -SO ₂ -CF ₂ -) to which they are bonded, and in this case, the group obtained by bonding R ^fc1 and R ^fc2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

In formula (1D), R ^fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A').

For details on the synthesis of sulfonium salts containing the anion represented by formula (1D), see JP-A-2010-215608 and JP-A-2014-133723.

Examples of the anion represented by formula (1D) include, but are not limited to, those shown below.

The photoacid generator containing the anion represented by formula (1D) does not have a fluorine atom at the α-position of the sulfo group, but has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave acid labile groups in the base polymer. Therefore, it can be used as a photoacid generator.

As the photoacid generator, a compound represented by the following formula (2) can also be suitably used.

In formula (2), R ²⁰¹ and R ²⁰² are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. R ²⁰³ is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. Any two of R ²⁰¹ , R ²⁰² and R ²⁰³ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring include the same as those exemplified in the explanation of formula (1-1) as the ring that can be formed by R ¹⁰¹ and R ¹⁰² bonding together with the sulfur atom to which they are bonded.

The hydrocarbyl groups represented by R ²⁰¹ and R ²⁰² may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, and tricyclo[5.2.1.0 ^2,6 cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a decanyl group, and an adamantyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group, and an anthracenyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, these groups may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like.

The hydrocarbylene group represented by R ²⁰³ may be saturated or unsaturated, and may be straight-chain, branched, or cyclic. Specific examples thereof include alkanediyl groups having 1 to 30 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, and heptadecane-1,17-diyl group; cyclopentanediyl group, cyclohexanediyl group, and the like. Examples of the aryl group include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl group, norbornanediyl group, and adamantanediyl group; arylene groups having 6 to 30 carbon atoms, such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, and tert-butylnaphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, so that the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferable.

In formula (2), L ^A is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, or a heteroatom. The hydrocarbylene group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbylene group represented by R ²⁰³ .

In formula (2), ^XA , ^XB , ^XC , and ^XD each independently represent a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of ^XA , ^XB , ^XC , and ^XD is a fluorine atom or a trifluoromethyl group.

In formula (2), k is an integer from 0 to 3.

The photoacid generator represented by formula (2) is preferably one represented by the following formula (2').

In formula (2'), L ^A is the same as above. R ^HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ³⁰¹ , R ³⁰² and R ³⁰³ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A'). x and y are each independently an integer of 0 to 5, and z is an integer of 0 to 4.

Examples of photoacid generators represented by formula (2) include those exemplified as photoacid generators represented by formula (2) in JP2017-026980A.

Among the photoacid generators, those containing an anion represented by formula (1A') or (1D) are particularly preferred because they have low acid diffusion and excellent solubility in solvents. Those represented by formula (2') are particularly preferred because they have extremely low acid diffusion.

As the photoacid generator, a sulfonium salt or an iodonium salt containing an anion having an aromatic ring substituted with an iodine atom or a bromine atom can be used. Examples of such salts include those represented by the following formula (3-1) or (3-2).

In formulas (3-1) and (3-2), p is an integer satisfying 1≦p≦3. q and r are integers satisfying 1≦q≦5, 0≦r≦3, and 1≦q+r≦5. q is preferably an integer satisfying 1≦q≦3, more preferably 2 or 3. r is preferably an integer satisfying 0≦r≦2.

In formulae (3-1) and (3-2), X ^BI represents an iodine atom or a bromine atom, and when p and/or q is 2 or more, they may be the same or different.

In formulae (3-1) and (3-2), ^L11 is a single bond, an ether bond, an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

In formulas (3-1) and (3-2), L ¹² is a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and is a (p+1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, which linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

In formulae (3-1) and (3-2), R ⁴⁰¹ is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms or a saturated hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or -N(R ^401A )(R ^401B ), -N(R ^401C )-C(=O)-R ^401D or -N(R ^401C )-C(=O)-O-R ^401D . R ^401A and R ^401B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^401C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. R ^401D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group and saturated hydrocarbylcarbonyloxy group may be linear, branched or cyclic. When p and/or r are 2 or more, each R ⁴⁰¹ may be the same or different.

Of these, preferred as R ⁴⁰¹ are a hydroxy group, --N(R ^401C )--C(=O)--R ^401D , --N(R ^401C )--C(=O)--R ^401D , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like.

In formulas (3-1) and (3-2), Rf ¹ to Rf ⁴ are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. Rf ¹ and Rf ² may combine to form a carbonyl group. In particular, it is preferable that Rf ³ and Rf ⁴ are both fluorine atoms.

In formulas (3-1) and (3-2), R ⁴⁰² to R ⁴⁰⁶ are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same as those exemplified as the hydrocarbyl groups represented by R ¹⁰¹ to R ¹⁰⁵ in the explanation of formulas (1-1) and (1-2). In addition, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone group, a sulfone group, or a sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. Furthermore, R ⁴⁰² and R ⁴⁰³ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring include the same rings as those exemplified in the explanation of formula (1-1) as the ring that can be formed when R ¹⁰¹ and R ¹⁰² are bonded to each other together with the sulfur atom to which they are bonded.

Cations of the sulfonium salt represented by formula (3-1) include the same as those exemplified as the cations of the sulfonium salt represented by formula (1-1). Furthermore, cations of the iodonium salt represented by formula (3-2) include the same as those exemplified as the cations of the iodonium salt represented by formula (1-2).

Examples of the anion of the onium salt represented by formula (3-1) or (3-2) include, but are not limited to, those shown below. In the following formula, X ^BI is the same as defined above.

When the resist material of the present invention contains an additive acid generator, the content is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The resist material of the present invention can function as a chemically amplified resist material because the base polymer contains the repeating unit f and/or contains an additive acid generator.

[Organic solvent]
The resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the above-mentioned components and the components described below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone described in paragraphs [0144] to [0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples of the monoethyl ether include ethers such as propylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; and lactones such as γ-butyrolactone.

In the resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvent may be used alone or in combination of two or more kinds.

[Other ingredients]
In addition to the above-mentioned components, surfactants, dissolution inhibitors, crosslinking agents, quenchers other than the fluorine atom-containing cyclic ammonium salt compound (hereinafter referred to as other quenchers), etc. can be appropriately combined and blended according to the purpose to form a positive resist material or a negative resist material, whereby the dissolution rate of the base polymer in the developer is accelerated by a catalytic reaction in the exposed area, so that a positive resist material or a negative resist material with extremely high sensitivity can be obtained. In this case, the dissolution contrast and resolution of the resist film are high, there is exposure margin, and the process adaptability is excellent, and the pattern shape after exposure is good, while the dimensional difference between the coarse and fine areas is small, in particular because the acid diffusion can be suppressed, and therefore the resist material is highly practical and can be very effective as a resist material for VLSI.

Examples of the surfactant include those described in paragraphs [0165] to [0166] of JP 2008-111103 A. The addition of a surfactant can further improve or control the coatability of the resist material. When the resist material of the present invention contains the surfactant, the content is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more types.

When the resist material of the present invention is a positive type, the difference in dissolution rate between the exposed and unexposed areas can be further increased by adding a dissolution inhibitor, thereby further improving the resolution. Examples of the dissolution inhibitor include a compound having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, and containing two or more phenolic hydroxyl groups in the molecule, in which the hydrogen atoms of the phenolic hydroxyl groups are substituted with acid labile groups at a ratio of 0 to 100 mol % as a whole, or a compound containing a carboxyl group in the molecule, in which the hydrogen atoms of the carboxyl groups are substituted with acid labile groups at an average ratio of 50 to 100 mol % as a whole. Specific examples include bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalene carboxylic acid, adamantane carboxylic acid, hydroxyl groups of cholic acid, and compounds in which the hydrogen atoms of the carboxyl groups are substituted with acid labile groups, and the like, and are described, for example, in paragraphs [0155] to [0178] of JP 2008-122932 A.

When the resist material of the present invention is a positive type and contains the dissolution inhibitor, the content is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more kinds.

On the other hand, when the resist material of the present invention is a negative type, a crosslinking agent can be added to reduce the dissolution rate of the exposed area to obtain a negative pattern. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, all of which are substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. These may be used as additives, or may be introduced as pendant groups into the polymer side chain. Compounds containing hydroxyl groups may also be used as crosslinking agents.

Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, triethylolethane triglycidyl ether, etc.

Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated or a mixture thereof, etc.

Examples of guanamine compounds include tetramethylol guanamine, tetramethoxymethyl guanamine, compounds in which 1 to 4 methylol groups of tetramethylol guanamine are methoxymethylated or mixtures thereof, tetramethoxyethyl guanamine, tetraacyloxyguanamine, compounds in which 1 to 4 methylol groups of tetramethylol guanamine are acyloxymethylated or mixtures thereof, etc.

Examples of glycoluril compounds include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated or mixtures thereof, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated or mixtures thereof, etc. Examples of urea compounds include tetramethylol urea, tetramethoxymethyl urea, compounds in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated or mixtures thereof, tetramethoxyethyl urea, etc.

Examples of isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, etc.

Examples of azide compounds include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

Examples of compounds containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

When the resist material of the present invention is a negative type and contains a crosslinking agent, the content is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more types.

Examples of the other quenchers include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, or tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and the like. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs [0146] to [0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, or compounds having a carbamate group described in JP-A-3790649, are preferred. By adding such basic compounds, for example, it is possible to further suppress the diffusion rate of the acid in the resist film or correct the shape.

Other quenchers include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids not fluorinated at the α-position, as described in JP-A-2008-158339. Sulfonic acids, imide acids, or methide acids fluorinated at the α-position are necessary to deprotect the acid labile group of a carboxylic acid ester, but a sulfonic acid or carboxylic acid not fluorinated at the α-position is released by salt exchange with an onium salt not fluorinated at the α-position. Sulfonic acids and carboxylic acids not fluorinated at the α-position do not undergo a deprotection reaction, and therefore function as quenchers.

Other quenchers include the polymer-type quencher described in JP 2008-239918 A. This enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. Polymer-type quenchers also have the effect of preventing pattern film loss and rounding of the pattern top when a protective film for immersion exposure is applied.

When the resist material of the present invention contains another quencher, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, per 100 parts by mass of the base polymer. The other quenchers may be used alone or in combination of two or more kinds.

The resist material of the present invention may contain a water repellency improver to improve the water repellency of the resist film surface. The water repellency improver can be used in immersion lithography without using a topcoat. As the water repellency improver, a polymer containing a fluorinated alkyl group, a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue of a specific structure, etc. are preferred, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferred. The water repellency improver needs to be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, a polymer containing a repeating unit containing an amino group or an amine salt is highly effective in preventing the evaporation of acid during PEB and preventing poor opening of a hole pattern after development. When the resist material of the present invention contains a water repellency improver, the content is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more kinds.

The resist material of the present invention may contain acetylene alcohols. Examples of the acetylene alcohols include those described in paragraphs [0179] to [0182] of JP 2008-122932 A. When the resist material of the present invention contains acetylene alcohols, the content is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more types.

[Pattern formation method]
When the resist material of the present invention is used in various integrated circuit manufacturing, known lithography techniques can be applied.For example, the pattern forming method includes the steps of forming a resist film on a substrate using the resist material described above, exposing the resist film to high energy radiation, and developing the exposed resist film using a developer.

First, the resist material of the present invention is applied onto a substrate for integrated circuit manufacture (Si, SiO ₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) or a substrate for mask circuit manufacture (Cr, CrO, CrON, MoSi ₂ , SiO ₂ , etc.) by a suitable application method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., so that the applied film has a thickness of 0.01 to 2 μm. This is then prebaked on a hot plate, preferably at 60 to 150° C. for 10 seconds to 30 minutes, more preferably at 80 to 120° C. for 30 seconds to 20 minutes, to form a resist film.

Next, the resist film is exposed to high energy radiation. Examples of the high energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, and the like. When ultraviolet radiation, far ultraviolet radiation, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, and the like are used as the high energy radiation, irradiation is performed directly or using a mask for forming a desired pattern so that the exposure amount is preferably about 1 to 200 mJ/cm ² , more preferably about 10 to 100 mJ/cm ^2. When EB is used as the high energy radiation, writing is performed directly or using a mask for forming a desired pattern so that the exposure amount is preferably about 0.1 to 100 μC/cm ² , more preferably about 0.5 to 50 μC/cm ² . The resist material of the present invention is particularly suitable for fine patterning using high-energy rays, such as i-rays with a wavelength of 365 nm, KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, gamma rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

After exposure, PEB may or may not be performed on a hot plate or in an oven, preferably at 30 to 150°C for 10 seconds to 30 minutes, more preferably at 50 to 120°C for 30 seconds to 20 minutes.

After exposure or PEB, the exposed resist film is developed using a developer of an alkaline aqueous solution of 0.1 to 10% by weight, preferably 2 to 5% by weight, such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), etc., for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form the desired pattern. In the case of a positive resist material, the part irradiated with light dissolves in the developer, while the part not exposed to light does not dissolve, forming a positive pattern on the substrate. In the case of a negative resist material, the opposite is true; that is, the part irradiated with light becomes insoluble in the developer, while the part not exposed to light dissolves.

A negative pattern can also be obtained by organic solvent development using a positive resist material containing a base polymer containing an acid labile group. The developers used in this case include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, Examples of the organic solvents include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents can be used alone or in combination of two or more.

After development is completed, rinsing is performed. A preferred rinsing solution is a solvent that is miscible with the developer and does not dissolve the resist film. Examples of such solvents that are preferably used include alcohols with 3 to 10 carbon atoms, ether compounds with 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents with 6 to 12 carbon atoms.

Specific examples of alcohols having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. , 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol, etc.

Examples of ether compounds having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

Aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene, etc.

Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not rinsing can reduce the amount of solvent used.

The hole pattern or trench pattern after development can also be shrunk using thermal flow, RELACS technology, or DSA technology. A shrink agent is applied onto the hole pattern, and the diffusion of acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, and the shrink agent adheres to the sidewalls of the hole pattern. The bake temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the bake time is preferably 10 to 300 seconds, removing excess shrink agent and shrinking the hole pattern.

The present invention will be specifically explained below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[Synthesis Example 1-1] Synthesis of Quencher Q-1 (1) Synthesis of Intermediate In-1

In an ice-cooled flask under a nitrogen atmosphere, trifluoroacetic acid (11.4 g) was added dropwise to 4-(2-hydroxyethyl)morpholine (5.0 g) and methylene chloride (100 g). After the addition, the reaction system was warmed to room temperature and aged for 17 hours. After aging, the solvent and excess trifluoroacetic acid were distilled off to obtain a fluorine atom-containing cyclic amine compound (intermediate In-1) as an oil (yield 8.7 g, 100%).

(2) Synthesis of Quencher Q-1

Under a nitrogen atmosphere, intermediate In-1 (1.0 g), 2,3,5-triiodobenzoic acid (2.2 g) and THF (5 g) were added to a flask and stirred at room temperature for 30 minutes. The solvent was then distilled off to obtain quencher Q-1 as a solid (yield 3.3 g, 100%).
The IR spectrum data and TOF-MS results of Quencher Q-1 are shown below. The nuclear magnetic resonance spectrum ( ¹ H-NMR/DMSO-d ₆ ) results are shown in Figure 1. A trace amount of residual solvent (THF) was observed in the ¹ H-NMR.
IR(D-ATR): ν= 3062, 1780, 1707, 1595, 1543, 1520, 1410, 1392, 1374, 1361, 1276, 1222, 1197, 1108, 1066, 1017, 1002, 911, 871, 839, 799, 778, 723, 706, 688, 677, 595, 509, 457 cm ^-1 .
TOF _- MS (MALDI): POSITIVE M ⁺ ₂₂₈ ( _C8H13F3NO3 ⁺ _equivalent )

[Synthesis Examples 1-2 to 1-35] Synthesis of Quenchers Q-2 to Q-35 As in Synthesis Example 1-1, quenchers Q-2 to Q-35 were synthesized by mixing a fluorine atom-containing cyclic amine compound with a carboxylic acid compound, a sulfonamide compound, a halogenated phenol compound or a hydrogen halide compound in a molar ratio of 1:1. The structures of quenchers Q-1 to Q-35 are shown below.

Synthesis Examples 2-1 to 2-4: Synthesis of base polymers (polymers P-1 to P-4) Each monomer was combined and copolymerized in THF, a solvent, and the reaction solution was poured into methanol. The precipitated solid was repeatedly washed with hexane, isolated, and dried to obtain base polymers (P-1 to P-4) with the compositions shown below. The compositions of the obtained base polymers were confirmed by ^1H -NMR, and Mw and Mw/Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[Examples 1 to 44, Comparative Examples 1 to 3] Preparation and Evaluation of Resist Materials (1) Preparation of Resist Materials Resist materials were prepared by filtering solutions in which each component was dissolved according to the compositions shown in Tables 1 to 3 through a 0.2 μm filter. The resist materials of Examples 1 to 21, Examples 23 to 44, and Comparative Examples 1 and 2 were positive-type, and the resist materials of Example 22 and Comparative Example 3 were negative-type.

In Tables 1 to 3, the components are as follows.
Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)
DAA (Diacetone Alcohol)

Acid generator: PAG-1 to PAG-4

Blend quenchers bQ-1 to bQ-3

Comparative quenchers: cQ-1, cQ-2

(2) EUV Lithography Evaluation Each resist material shown in Tables 1 to 3 was spin-coated on a Si substrate formed with a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. with a film thickness of 20 nm, and pre-baked at 100 ° C. for 60 seconds using a hot plate to prepare a resist film with a film thickness of 50 nm. This was exposed using an EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, a hole pattern mask with a pitch of 44 nm on the wafer and a bias of +20%) manufactured by ASML, and PEB was performed for 60 seconds on a hot plate at the temperatures listed in Tables 1 to 3, and development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution to obtain a hole pattern with a size of 22 nm in Examples 1 to 21, Examples 23 to 44, and Comparative Examples 1 and 2, and a dot pattern with a size of 22 nm in Example 22 and Comparative Example 3.
Using a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, the exposure dose when holes or dots were formed with a dimension of 22 nm was measured and used as the sensitivity, and the dimensions of 50 holes or dots at this time were measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to use as the dimension variation (CDU). The results are shown in Tables 1 to 3.

The results shown in Tables 1 to 3 show that the resist material of the present invention containing the fluorine atom-containing cyclic ammonium salt compound has high sensitivity and small CDU.

Claims (13)

A resist material comprising a base polymer and a quencher comprising a salt compound represented by the following formula (A):

(In the formula, ring R is an alicyclic group having 2 to 12 carbon atoms formed together with the nitrogen atom in the formula, and the ring may contain an ether bond, a thioether bond, a carbonyl group, -N(R')- or a sulfonyl group. R' is a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms or ^-L3 - ^R3 .
L ¹ , L ² and L ³ are each independently a single bond, an ester bond, a sulfonyl group or an alkanediyl group having 1 to 6 carbon atoms, some of the hydrogen atoms of the alkanediyl group may be substituted with a hydroxy group, a hydrocarbyloxy group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, or a hydrocarbylcarbonyloxy group having 2 to 12 carbon atoms which may be substituted with a fluorine atom, and some of the methylene groups constituting the alkanediyl group may be substituted with an ether bond, an ester bond, an amide bond, a sulfonyl group, a sulfonate ester bond or a sulfonamide bond, provided that L ¹ , L ² and L ³ do not include a tertiary ester structure.
R ¹ , R ² and R ³ each independently represent a hydrogen atom, a saturated hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 10 carbon atoms, a saturated hydrocarbyl group having 1 to 16 carbon atoms and substituted with at least three fluorine atoms, an aryl group having 6 to 10 carbon atoms and substituted with at least three fluorine atoms, or a group obtained by combining these, and one or both of R ¹ and R ² have at least three fluorine atoms.
X ⁻ is a carboxylate anion, a sulfonamide anion, a halogenated phenoxide anion, or a halide anion. 2. The resist material according to claim 1, wherein X ⁻ is a carboxylate anion containing an iodine atom or a bromine atom, a sulfonamide anion containing an iodine atom or a bromine atom, or a phenoxide anion containing an iodine atom or a bromine atom. The resist material according to claim 1 or 2, further comprising an acid generator that generates a sulfonic acid, an imide acid, or a methide acid. The resist material according to any one of claims 1 to 3 further comprises an organic solvent. The resist material according to any one of claims 1 to 4, wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2):

(In the formula, each R ^A is independently a hydrogen atom or a methyl group.
Y ¹ is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring.
^Y2 is a single bond or an ester bond.
^Y3 is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are each independently an acid labile group.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group or a saturated hydrocarbyl group having 1 to 6 carbon atoms.
R ¹⁴ is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with ether bonds or ester bonds.
a is 1 or 2. b is an integer from 0 to 4, provided that 1≦a+b≦5. The resist material according to claim 5, which is a chemically amplified positive resist material. The resist material according to any one of claims 1 to 4, wherein the base polymer does not contain an acid labile group. The resist material according to claim 7, which is a chemically amplified negative resist material. The resist material according to any one of claims 1 to 8 further comprises a surfactant. The resist material according to any one of claims 1 to 9, wherein the base polymer further comprises at least one repeating unit selected from the group consisting of repeating units represented by the following formulas (f1) to (f3):

(In the formula, each R ^A is independently a hydrogen atom or a methyl group.
Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ¹¹ -, -C(═O)-O-Z ¹¹ -, or -C(═O)-NH-Z ¹¹ -. ^{Z 11} is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.
^Z2 is a single bond or an ester bond.
Z ³¹ is a single bond, -Z ³¹ -C(═O)-O-, -Z ³¹ -O-, or -Z ³¹ -O-C(═O)-. Z ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom.
^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group or a carbonyl group.
^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- or -C(=O)-NH- ^Z51- . ^Z51 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group.
R ²¹ to R ²⁸ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R ²³ and R ²⁴ , or R ²⁶ and R ²⁷ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
M ⁻ is a non-nucleophilic counter ion. A pattern forming method comprising the steps of forming a resist film on a substrate using the resist material according to any one of claims 1 to 10, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer. The pattern formation method according to claim 11, wherein the high energy radiation is an i-line having a wavelength of 365 nm, an ArF excimer laser beam having a wavelength of 193 nm, or a KrF excimer laser beam having a wavelength of 248 nm. The pattern formation method according to claim 11, wherein the high-energy beam is an electron beam or extreme ultraviolet light having a wavelength of 3 to 15 nm.