JP2021170101A - Resist material and patterning process - Google Patents

Abstract

To provide a resist material that offers high sensitivity and is small in LWR and CDU independent of whether it is a positive or negative one, and a patterning process using the same.SOLUTION: A resist material comprises an acid generator containing a sulfonium salt represented by the formula (1).SELECTED DRAWING: None

Description

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

With the increasing integration and speed of LSI, the miniaturization of pattern rules is rapidly progressing. In particular, the expansion of the logic memory market due to the spread of smartphones is driving miniaturization. As a state-of-the-art miniaturization technology, mass production of 10 nm node devices by double patterning of ArF immersion lithography is being carried out, and preparations for mass production of 7 nm nodes by double patterning are also underway for the next generation. Extreme ultraviolet (EUV) lithography is a candidate for the next-generation 5 nm node.

In EUV resist materials, it is necessary to achieve high sensitivity, high resolution and low edge roughness (LWR) at the same time. When the acid diffusion distance is shortened, the LWR becomes smaller, but the sensitivity becomes lower. For example, lowering the post-exposure bake (PEB) temperature reduces the LWR but lowers the sensitivity. Even if the amount of the quencher added is increased, the LWR becomes smaller, but the sensitivity is lowered. It is necessary to break the trade-off relationship between sensitivity and LWR.

EUV has a wavelength that is an order of magnitude shorter and an energy density that is an order of magnitude higher than that of ArF excimer laser light. As a result, the number of photons exposed to the photoresist layer in EUV exposure is very small, which is 1/14 of that of ArF light, and the variation in photons affects the variation in dimensions (LWR and dimensional uniformity (CDU)). It is said to exert. In addition, due to the variation of photons, a phenomenon occurs in which the hole pattern does not open with a probability of 1 in millions. It has been pointed out that it is necessary to increase the light absorption of the photoresist material in order to reduce the variation of photons.

Sulfonium salts having a benzene ring substituted with a halogen atom have been proposed (Patent Documents 1 to 3). Having a halogen atom on the cation side, which absorbs a large amount of EUV, has the effect of accelerating the decomposition of the cation in EUV exposure and improving the sensitivity. However, the absorption of fluorine atoms was not so high, and although the absorption of iodine atoms was high, the iodine atoms bonded to aromatic groups were stable and the sensitizing effect was limited.

Japanese Unexamined Patent Publication No. 2012-107151 Japanese Unexamined Patent Publication No. 2017-15777 Japanese Unexamined Patent Publication No. 2018-118962

In a chemically amplified resist material using an acid as a catalyst, it is desired to develop an acid generator capable of reducing LWR and hole pattern CDU with high sensitivity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist material having high sensitivity and a small LWR and CDU, and a pattern forming method using the same, regardless of whether it is a positive resist material or a negative resist material. And.

As a result of diligent studies to achieve the above object, the present inventors have found a hydrocarbyl group substituted with an iodine atom or a bromine atom (however, the aromatic ring substituted with an iodine atom or a bromine atom is not included). By using a sulfonium salt having a structure bonded to a benzene ring via an ester bond-containing group as an acid generator, it has high sensitivity, small LWR and CDU, high contrast, excellent resolution, and a wide process margin. The present invention has been completed by finding that a resist material can be obtained.

（式中、ｋ、ｍ及びｎは、それぞれ独立に、１〜３の整数である。ｐは、０又は１である。ｑは、０〜４の整数である。ｒは、１〜３の整数である。
Ｘ^BIは、ヨウ素原子又は臭素原子である。
Ｒ^alは、炭素数１〜２０の(ｋ＋１)価の脂肪族炭化水素基であり、エーテル結合、カルボニル基、エステル結合、アミド結合、スルトン環、ラクタム環、カーボネート基、ヨウ素原子以外のハロゲン原子、炭素数６〜１２のアリール基、ヒドロキシ基及びカルボキシ基から選ばれる少なくとも１種を含んでいてもよい。
Ｘ¹は、単結合、エーテル結合、エステル結合、アミド結合、カルボニル基又はカーボネート基である。
Ｘ²は、単結合、又は炭素数１〜２０の(ｍ＋１)価の炭化水素基であり、エーテル結合、カルボニル基、エステル結合、アミド結合、スルトン環、ラクタム環、カーボネート基、ヨウ素原子以外のハロゲン原子、ヒドロキシ基及びカルボキシ基から選ばれる少なくとも１種を含んでいてもよい。
Ｘ³は、単結合、エーテル結合又はエステル結合である。
Ｒ¹は、単結合、又はエーテル結合、エステル結合若しくはヒドロキシ基を含んでいてもよい炭素数１〜２０の飽和ヒドロカルビレン基である。
Ｒ²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。ｒ＝１のとき、２つのＲ²は、互いに同一でも異なっていてもよく、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もよい。
Ｒ³は、ヒドロキシ基、カルボキシ基、ニトロ基、シアノ基、フッ素原子、塩素原子、臭素原子、ヨウ素原子、アミノ基、又はフッ素原子、塩素原子、臭素原子、ヨウ素原子、ヒドロキシ基、アミノ基若しくはエーテル結合を含んでいてもよい、炭素数１〜２０の飽和ヒドロカルビル基、炭素数１〜２０の飽和ヒドロカルビルオキシ基、炭素数２〜２０の飽和ヒドロカルビルカルボニルオキシ基、炭素数２〜２０の飽和ヒドロカルビルオキシカルボニル基若しくは炭素数１〜４の飽和ヒドロカルビルスルホニルオキシ基である。
Ｘ^-は、非求核性対向イオンである。）
２．前記非求核性対向イオンが、フッ素化されたスルホン酸イオン、フッ素化されたイミド酸イオン又はフッ素化されたメチド酸イオンである１のレジスト材料。
３．更に、ベースポリマーを含む１又は２のレジスト材料。
４．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３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、エーテル結合若しくはラクトン環を有する炭素数１〜１２の連結基である。
Ｙ²は、単結合、エステル結合又はアミド結合である。
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、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、炭素数１〜６の飽和ヒドロカルビル基、炭素数１〜６の飽和ヒドロカルビルオキシ基、炭素数２〜７の飽和ヒドロカルビルカルボニル基、炭素数２〜７の飽和ヒドロカルビルカルボニルオキシ基又は炭素数２〜７の飽和ヒドロカルビルオキシカルボニル基である。
Ｒ¹⁴は、単結合又は炭素数１〜６の飽和ヒドロカルビレン基であり、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。）
５．化学増幅ポジ型レジスト材料である４のレジスト材料。
６．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３のレジスト材料。
７．化学増幅ネガ型レジスト材料である６のレジスト材料。
８．前記ベースポリマーが、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種を含むものである１〜７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、フェニレン基、−Ｏ−Ｚ¹¹−、−Ｃ(＝Ｏ)−Ｏ−Ｚ¹¹−又は−Ｃ(＝Ｏ)−ＮＨ−Ｚ¹¹−であり、Ｚ¹¹は、炭素数１〜６の脂肪族ヒドロカルビレン基又は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。
Ｚ²は、単結合、−Ｚ²¹−Ｃ(＝Ｏ)−Ｏ−、−Ｚ²¹−Ｏ−又は−Ｚ²¹−Ｏ−Ｃ(＝Ｏ)−である。Ｚ²¹は、炭素数１〜１２の飽和ヒドロカルビレン基であり、カルボニル基、エステル結合又はエーテル結合を含んでいてもよい。
Ｚ³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、−Ｏ−Ｚ³¹−、−Ｃ(＝Ｏ)−Ｏ−Ｚ³¹−又は−Ｃ(＝Ｏ)−ＮＨ−Ｚ³¹−である。Ｚ³¹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、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、Ｒ²⁴及びＲ²⁵のいずれか２つ又はＲ²⁶、Ｒ²⁷及びＲ²⁸のいずれか２つが、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もよい。
Ａ¹は、水素原子又はトリフルオロメチル基である。
Ｍ^-は、非求核性対向イオンである。）
９．更に、有機溶剤を含む１〜８のいずれかのレジスト材料。
１０．更に、クエンチャーを含む１〜９のいずれかのレジスト材料。
１１．更に、界面活性剤を含む１〜１０のいずれかのレジスト材料。
１２．１〜１１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。
１３．前記高エネルギー線が、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１２のパターン形成方法。
１４．前記高エネルギー線が、ＥＢ又は波長３〜１５ｎｍのＥＵＶである１２のパターン形成方法。 That is, the present invention provides the following resist material and pattern forming method.
1. 1. A resist material containing an acid generator containing a sulfonium salt represented by the following formula (1).

(In the equation, k, m and n are each independently an integer of 1 to 3. p is 0 or 1. q is an integer of 0 to 4. r is an integer of 1 to 3. It is an integer.
X ^BI is an iodine atom or a bromine atom.
R ^al is a (k + 1) -valent aliphatic hydrocarbon group having 1 to 20 carbon atoms, and is an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, a carbonate group, or a halogen atom other than an iodine atom. , At least one selected from an aryl group having 6 to 12 carbon atoms, a hydroxy group and a carboxy group may be contained.
X ¹ is a single bond, an ether bond, an ester bond, an amide bond, a carbonyl group or a carbonate group.
X ² is a single bond or a (m + 1) valent hydrocarbon group having 1 to 20 carbon atoms, other than an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, a carbonate group, and an iodine atom. It may contain at least one selected from a halogen atom, a hydroxy group and a carboxy group.
X ³ is a single bond, ether bond or ester bond.
R ¹ is a saturated hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, an ester bond or a hydroxy group.
R ² is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. When r = 1, the two R ^2s may be the same or different from each other and may be bonded to each other to form a ring with the sulfur atoms to which they are bonded.
R ³ is a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an amino group, or a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, 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 hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, and a saturated hydrocarbyl group having 2 to 20 carbon atoms, which may contain an ether bond. It is an oxycarbonyl group or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms.
X ^- is a non-nucleophilic opposing ion. )
2. The resist material of 1 in which the non-nucleophilic counter ion is a fluorinated sulfonic acid ion, a fluorinated imidate ion, or a fluorinated methideate ion.
3. 3. Further, one or two resist materials containing a base polymer.
4. 3. The resist material of 3 in which 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, ^RA is a hydrogen atom or a methyl group, respectively.
Y ¹ is a linking group having 1 to 12 carbon atoms having a single bond, a phenylene group or a naphthylene group, or an ester bond, an ether bond or a lactone ring.
Y ² is a single bond, an ester bond or an amide bond.
Y ³ is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are acid-labile groups.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, and 2 carbon atoms. It is a saturated hydrocarbylcarbonyloxy group of ~ 7 or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms.
R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and a part of the carbon atom thereof may be substituted with an ether bond or an ester bond.
a is 1 or 2. b is an integer from 0 to 4. )
5. 4 resist materials which are chemically amplified positive resist materials.
6. The resist material of 3 in which the base polymer does not contain an acid unstable group.
7. 6 resist materials which are chemically amplified negative type resist materials.
8. The resist material according to any one of 1 to 7, wherein the base polymer contains at least one selected from the repeating units represented by the following formulas (f1) to (f3).

(In the formula, ^RA is a hydrogen atom or a methyl group, respectively.
Z ¹ is a single bond, a phenylene ^{group, -O-Z 11 -, -} C (= O) -O-Z 11 - or -C (= O) -NH-Z 11 - a and, Z ¹¹ is carbon It is an aliphatic hydrocarbylene group or a phenylene group of the number 1 to 6, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group.
Z ² is a single ^{bond, -Z 21 -C (= O)} -O -, - Z 21 -O- or ^{-Z 21 -O-C (= O} ) - is. Z ²¹ is a saturated hydrocarbylene group having 1 to 12 carbon atoms and may contain a carbonyl group, an ester bond or an ether bond.
Z ³ is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene ^{group, -O-Z 31 -, -} C (= O) -O-Z 31 - or -C (= O) -NH- Z ³¹ −. Z ³¹ is a phenylene group substituted with an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group having 1 to 6 carbon atoms, and is a carbonyl group, an ester bond, an ether bond, or a hydroxy group. May include.
R ^{21 to} R ²⁸ are hydrocarbyl groups having 1 to 20 carbon atoms, which may independently contain heteroatoms. Further, ^{any two of R 23} , R ²⁴ and R ²⁵ or any two of R ²⁶ , R ²⁷ and R ²⁸ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
A ¹ is a hydrogen atom or a trifluoromethyl group.
M ^- is a non-nucleophilic opposing ion. )
9. Further, any of 1 to 8 resist materials containing an organic solvent.
10. Further, any resist material of 1 to 9 containing a quencher.
11. Further, any of 1 to 10 resist materials containing a surfactant.
A step of forming a resist film on a substrate using any of the resist materials of 12.1 to 11, a step of exposing the resist film with high energy rays, and a step of exposing the exposed resist film with a developing solution. A pattern forming method including a step of developing.
13. Twelve pattern forming methods in which the high-energy rays are ArF excimer laser light having a wavelength of 193 nm or KrF excimer laser light having a wavelength of 248 nm.
14. Twelve pattern forming methods in which the high energy rays are EB or EUV having a wavelength of 3 to 15 nm.

Since the sulfonium salt represented by the formula (1) has an iodine atom or a bromine atom having a large atomic weight, it has a feature that acid diffusion is small. Since the absorption of EUV with a wavelength of 13.5 nm by iodine atoms is very large and the bromine atoms are easily ionized, secondary electrons are generated from the iodine atoms and bromine atoms during exposure. In addition, radicals are generated from the iodine atom bonded to the alkyl group, and these actions promote the decomposition of the sulfonium salt and increase the sensitivity. These make it possible to construct a resist material having high sensitivity, low LWR and low CDU.

[Resist material]
The resist material of the present invention contains a sulfonium salt represented by the formula (1), and in some cases contains a base polymer. The sulfonium salt is an acid generator in which the cation is decomposed by light irradiation to generate an anionic acid. When the anion of the sulfonium salt is a fluorinated sulfonic acid, a fluorinated imide acid, or a fluorinated methidoic acid, it acts as an acid generator.

Since the sulfonium salt-type acid generator used in the present invention has a hydrocarbyl group substituted with an iodine atom or a bromine atom in the cation (however, it does not contain an aromatic ring substituted with an iodine atom or a bromine atom). , EUV absorption is large and decomposition efficiency is high. JP-A-2018-5224 and JP-A-2018-25789 describe sulfonium salts and iodonium salts having an iodinated benzene ring as an anion, and increase the absorption of light by the anion. It is becoming more sensitive. Since the sulfonium salt has a mechanism in which the cation absorbs light and the cation is decomposed, it is more effective to increase the sensitivity by increasing the absorption of the cation.

Since the sulfonium salt used in the present invention has an iodine atom or a bromine atom having a large atomic weight introduced into the cation, the diffusion is small and the compatibility with the polymer is high, so that the dispersibility is excellent, whereby LWR and CDU can be obtained. improves.

The effect of improving LWR and CDU by the sulfonium salt-type acid generator represented by the formula (1) is effective in both positive pattern formation and negative pattern formation by alkaline aqueous solution development and negative pattern formation in organic solvent development. be.

The sulfonium salt represented by the formula (1) is used as a positive resist material because the exposed portion dissolves in an alkaline aqueous solution when a simple substance is dissolved in a solvent to form a film without blending with the base polymer. You can also.

[Sulfonium salt]
The sulfonium salt contained in the resist material of the present invention is represented by the following formula (1).

In the formula (1), k, m and n are each independently an integer of 1 to 3. p is 0 or 1. q is an integer from 0 to 4. r is an integer from 1 to 3.

In formula (1), X ^BI is an iodine atom or a bromine atom.

In the formula (1), R ^al is a (k + 1) -valent aliphatic hydrocarbon group having 1 to 20 carbon atoms, and contains an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, and a carbonate group. It may contain at least one selected from a halogen atom other than the iodine atom, an aryl group having 6 to 12 carbon atoms, a hydroxy group and a carboxy group.

The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, and a propane-1,3. -Diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane -1,4-diyl group, 1,1-dimethylethane-1,2-diyl group, pentane-1,5-diyl group, 2-methylbutane-1,2-diyl group, hexane-1,6-diyl group , Heptane-1,7-diyl group, octane-1,8-diyl group, nonan-1,9-diyl group, decan-1,10-diyl group, undecane-1,11-diyl group, dodecane-1, Alkanediyl group such as 12-diyl group; cyclopropane-1,1-diyl group, cyclopropane-1,2-diyl group, cyclobutane-1,1-diyl group, cyclobutane-1,2-diyl group, cyclobutane- 1,3-diyl group, cyclopentane-1,1-diyl group, cyclopentane-1,2-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,1-diyl group, cyclohexane-1, Cycloalkanediyl groups such as 2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group; polycycles such as norbornan-2,3-diyl group and norbornan-2,6-diyl group Formula Saturated hydrocarbylene group; alkanediyl group such as 2-propene-1,1-diyl group; alkanediyl group such as 2-propin-1,1-diyl group; 2-cyclohexene-1,2-diyl group, 2- Cycloalkendyl group such as cyclohexene-1,3-diyl group, 3-cyclohexene-1,2-diyl group; polycyclic unsaturated hydrocarbylene group such as 5-norbornene-2,3-diyl group; cyclopentylmethane Cyclic aliphatic hydrocarbylene groups such as diyl group, cyclohexylmethanediyl group, 2-cyclopentenylmethanediyl group, 3-cyclopentenylmethanediyl group, 2-cyclohexenylmethanediyl group, 3-cyclohexenylmethanediyl group. Substituted alkanediyl groups; examples thereof include tri- or tetravalent groups obtained by desorbing one or two hydrogen atoms from these groups.

Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xsilyl group, a 1-naphthyl group, a 2-naphthyl group and the like.

In formula (1), X ¹ is a single bond, an ether bond, an ester bond, an amide bond, a carbonyl group or a carbonate group. X ² is a single bond or a (m + 1) valent hydrocarbon group having 1 to 20 carbon atoms, other than an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, a carbonate group, and an iodine atom. It may contain at least one selected from a halogen atom, a hydroxy group and a carboxy group. X ³ is a single bond, ether bond or ester bond.

In the formula (1), R ¹ is a saturated hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, an ester bond or a hydroxy group. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include the same as the above-mentioned alkanediyl group, cycloalkanediyl group, and polycyclic saturated hydrocarbylene group. Can be mentioned. As the saturated hydrocarbylene group, an alkanediyl group is preferable.

In formula (1), R ² is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be linear, branched or cyclic, and specific examples thereof include a saturated hydrocarbyl group having 1 to 20 carbon atoms, an unsaturated aliphatic hydrocarbyl group having 2 to 20 carbon atoms, and 6 carbon atoms. Examples thereof include an aryl group of ~ 20, an aralkyl group having 7 to 20 carbon atoms, a group obtained by combining these, and the like.

The saturated hydrocarbyl group may be linear, branched or cyclic, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and a sec-butyl group. Group, tert-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, Alkyl groups such as n-dodecyl group, n-tridecyl group, n-pentadecyl group and n-hexadecyl group; cyclic saturated hydrocarbyl groups such as cyclopentyl group and cyclohexyl group can be mentioned.

The unsaturated aliphatic hydrocarbyl group may be linear, branched or cyclic, and specific examples thereof include an alkenyl group such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group and a hexenyl group. , Alkinyl groups such as ethynyl group, propynyl group and butynyl group, and cyclic unsaturated hydrocarbyl group such as cyclohexenyl group.

Examples of the aryl group include 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 and a naphthyl. Examples thereof include a 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 the like.

Examples of the aralkyl group include a benzyl group and a phenethyl group.

Further, a part or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom and halogen atom, and a part of carbon atoms of these groups may be substituted. , Oxygen atom, sulfur atom, nitrogen atom and the like may be substituted with a hetero atom-containing group, and as a result, a hydroxy group, a carboxy group, a halogen atom, a cyano group, an amino group, a nitro group, a sulton group, a sulfone group, It may contain a sulfonium salt-containing group, an ether bond, an ester bond, a carbonyl group, a sulfide bond, a sulfonyl group, an amide bond and the like.

（式中、破線は、式（１）中の芳香環との結合手である。） When r = 1, the two R ^2s may be the same or different from each other and may be bonded to each other to form a ring with the sulfur atoms to which they are bonded. At this time, the ring preferably has the structure shown below.

(In the formula, the broken line is the bond with the aromatic ring in formula (1).)

In formula (1), R ³ is a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an amino group, or a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, Saturated hydrocarbyl group having 1 to 20 carbon atoms, saturated hydrocarbyloxy group having 1 to 20 carbon atoms, saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, carbon number of carbons, which may contain a hydroxy group, an amino group or an ether bond. It is a saturated hydrocarbyloxycarbonyl group of 2 to 20 or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms.

The saturated hydrocarbyloxy group may be linear, branched or cyclic, and specific examples thereof include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group and an isobutyloxy group. , Se-butyloxy group, tert-butyloxy group, n-pentyloxy group, neopentyloxy group, cyclopentyloxy group, n-hexyloxy group, cyclohexyloxy group, n-heptyloxy group, n-octyloxy group, 2- Ethylhexyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group and the like. Be done.

Examples of the saturated hydrocarbylcarbonyloxy group include an acetyloxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group and the like.

Examples of the saturated hydrocarbyloxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propyloxycarbonyl group, an isopropyloxycarbonyl group, an n-butyloxycarbonyl group, an isobutyloxycarbonyl group, a sec-butyloxycarbonyl group, and a tert-. Butyloxycarbonyl group, n-pentyloxycarbonyl group, neopentyloxycarbonyl group, cyclopentyloxycarbonyl group, n-hexyloxycarbonyl group, cyclohexyloxycarbonyl group, n-heptyloxycarbonyl group, n-octyloxycarbonyl group, 2 -Ethylhexyloxycarbonyl group, n-nonyloxycarbonyl group, n-decyloxycarbonyl group, n-undecyloxycarbonyl group, n-dodecyloxycarbonyl group, n-tridecyloxycarbonyl group, n-pentadecyloxycarbonyl group And so on.

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

The method for synthesizing the cation of the sulfonium salt represented by the formula (1) has a hydrocarbyl group substituted with an iodine atom or a bromine atom (however, it does not include an aromatic ring substituted with an iodine atom or a bromine atom). Esteration reaction of carboxylic acid or carboxylic acid ester with sulfonium salt having benzene ring substituted with hydroxy group or halogen atom, or substitution of carboxylic acid or carboxylic acid ester substituted with chlorine atom with hydroxy group or halogen atom After esterification with a sulfonium salt having a benzene ring, it can be synthesized by reacting with sodium iodide or sodium bromide and substituting the chlorine atom with an iodine atom or a bromine atom.

In formula (1), X ^- is a non-nucleophilic opposing ion. Examples of the non-nucleophilic counter ion include a fluorinated sulfonic acid ion, a fluorinated imidate ion, and a fluorinated methylated acid ion.

Specifically, fluoroalkyl sulfonate ions such as triflate ion, 2,2,2-trifluoroethanesulfonate ion, nonafluorobutane sulfonate ion, tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, 2, Examples thereof include aryl sulfonate ions such as 3,4,5,6-pentafluorobenzene sulfonate ions.

As other examples, JP-A-2004-531749, JP-A-2007-145977, JP-A-2008-7410, JP-A-2018-101130, JP-A-2018-49177, International Publication No. 2011 / Α-fluorosulfonic acid anion described in 093139, β-fluorosulfonic acid anion described in JP-A-2014-133725, α-fluorosulfonic acid anion described in JP-A-2014-126767, fluoroimide acid anion, fluoromethidic acid. Examples thereof include an anions and the fluorosulfonimide acid anions described in JP-A-2016-210761. As still another example, there is a fluorosulfonic acid anion having an aromatic group substituted with an iodine atom described in JP-A-2018-5224 and JP-A-2018-25789.

These anions are strong acids that can carry out a deprotection reaction of the acid unstable group of the positive resist material, and carry out a cross-linking reaction and a polarity conversion reaction of the negative resist material.

X ^- include examples of the anion represented by include the anions selected from the following formulas (1A) ~ (1D).

In formula (1A), R ^fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the formula (1A') described later.

As the anion represented by the formula (1A), the anion represented by the following formula (1A') is preferable.

In formula (1A'), R ⁴ is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ⁵ is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a hetero atom. As the hetero atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom and the like are preferable, and an oxygen atom is more preferable. The hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms from the viewpoint of obtaining high resolution in fine pattern formation.

The ^{hydrocarbyl group represented by R 5} may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group and 2-ethylhexyl group. , Nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group and other alkyl groups; cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbol Cyclic saturated hydrocarbyl group such as nylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl group such as allyl group and 3-cyclohexenyl group. Aryl groups such as phenyl group, 1-naphthyl group and 2-naphthyl group; aralkyl groups such as benzyl group and diphenylmethyl group can be mentioned. Further, a part or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom and halogen atom, and a part of carbon atoms of these groups may be substituted. It may be substituted with a hetero atom-containing group such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, or a lactone ring. , Sulton ring, carboxylic acid anhydride, haloalkyl group and the like may be contained. Hydrocarbyl groups containing heteroatoms include tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy) methyl group, acetoxymethyl group and 2-carboxy. Examples thereof include a -1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group and a 3-oxocyclohexyl group.

Regarding the synthesis of a sulfonium salt containing an anion represented by the formula (1A'), JP-A-2007-145977, JP-A-2008-106045, JP-A-2009-7327, and JP-A-2009-258695 And so on. Further, the sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644 and the like are also preferably used.

Examples of the anion represented by the 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 hydrocarbyl groups having 1 to 40 carbon atoms which may independently contain a fluorine atom or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the formula (1A'). The R ^fb1 and R ^fb2 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R ^fb1 and R ^fb2 may be bonded to each other to form a ring together with _{a group (−CF 2} −SO ₂ −N ⁻ −SO ₂ −CF _{2 −) to which they are bonded.} ^The group obtained by bonding fb1 and R ^fb2 to each other is preferably an ethylene fluorinated group or a propylene fluorinated group.

In the formula (1C), R ^fc1 , R ^fc2 and R ^fc3 are hydrocarbyl groups having 1 to 40 carbon atoms which may independently contain a fluorine atom or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the 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. Further, R ^fc1 and R ^fc2 may be bonded to each other to form a ring together with _{a group (−CF 2} −SO ₂ −C ⁻ −SO ₂ −CF _{2 −) to which they are bonded.} ^The group obtained by bonding fc1 and R ^fc2 to each other is preferably an ethylene fluorinated group or a propylene fluorinated 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 those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the formula (1A').

The synthesis of a sulfonium salt containing an anion represented by the formula (1D) is described in detail in JP-A-2010-215608 and JP-A-2014-133723.

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

X ^- include other examples of the anion represented by include those represented by the following formula (1E).

In the formula (1E), s and t are integers satisfying 1 ≦ s ≦ 5, 0 ≦ t ≦ 3 and 1 ≦ s + t ≦ 5. s is preferably an integer satisfying 1 ≦ s ≦ 3, more preferably 2 or 3. t is preferably an integer satisfying 0 ≦ t ≦ 2. u is an integer that satisfies 1 ≦ u ≦ 3.

In formula (1E), X ^BI is an iodine atom or a bromine atom, and when s and / or u are 2 or more, they may be the same or different from each other.

In formula (1E), L ¹ is a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain a single bond, an ether bond or an ester bond, or an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched or cyclic.

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

In formula (1E), R ⁶ contains a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond. It may be a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 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 carbon number of carbon atoms. 1 to 20 saturated hydrocarbylsulfonyloxy groups, or -NR ^6A- C (= O) -R ^6B or -NR ^6A- C (= O) -OR ^6B . R ^6A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, 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 hydrocarbyl group having 2 carbon atoms. It may contain ~ 6 saturated hydrocarbylcarbonyloxy groups. R ^6B is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 carbon atoms, a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, and a saturated hydrogen group having 2 to 6 carbon atoms. It may contain a hydrocarbylcarbonyl group 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 t and / or u are 2 or more, each R ⁶ may be the same as or different from each other.

Of these, R ⁶ includes a hydroxy group, -NR ^6A- C (= O) -R ^6B , -NR ^6A- C (= O) -O-R ^6B , fluorine atom, chlorine atom, bromine atom, and methyl. A group, a methoxy group and the like are preferable.

In formula (1E), Rf ^{1 to Rf 4} are independently hydrogen atoms, fluorine atoms or trifluoromethyl groups, but at least one of them is a fluorine atom or trifluoromethyl group. Further, Rf ¹ and Rf ² may be combined to form a carbonyl group. In particular, it is preferable that both ^{Rf 3} and Rf ^{4 are fluorine atoms.}

Specific examples of the anion represented by the formula (1E) include, but are not limited to, those shown below. In the following formula, X ^BI is the same as above.

The sulfonium salt represented by the formula (1) is, for example, the salt composed of the sulfonium cation having an anion and a hydroxy group and a hydrocarbyl group substituted with an iodine atom or a bromine atom (however, substituted with an iodine atom or a bromine atom). It can be synthesized by an esterification reaction with a carboxylic acid or a carboxylic acid chloride having (does not contain an aromatic ring).

The resist material of the present invention containing the sulfonium salt represented by the formula (1) can be patterned without containing the base polymer, but can also be blended with the base polymer. When blended with the base polymer, the content of the sulfonium salt represented by the formula (1) is 0.01 to 1,000 mass by mass with respect to 100 parts by mass of the base polymer, which will be described later, in terms of sensitivity and acid diffusion suppressing effect. Parts are preferable, and 0.05 to 500 parts by mass is more preferable.

[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 containing an acid unstable group. As the repeating unit containing an acid unstable group, a repeating unit represented by the following formula (a1) (hereinafter, also referred to as a repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter, repeating unit a2). Also referred to as) is preferable.

In formulas (a1) and (a2), ^RA is independently a hydrogen atom or a methyl group. Y ¹ is a linking group having 1 to 12 carbon atoms having a single bond, a phenylene group or a naphthylene group, or an ester bond, an ether bond or a lactone ring. Y ² is a single bond, an ester bond or an amide bond. Y ³ is a single bond, an ether bond or an ester bond. R ¹¹ and R ¹² are acid-labile groups. R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, and 2 carbon atoms. It is a saturated hydrocarbylcarbonyloxy group of ~ 7 or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and a part of its carbon atom may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer from 0 to 4.

Examples of the monomer that gives the repeating unit a1 include, but are not limited to, those shown below. In the following formula, ^RA and R ¹¹ are the same as described above.

Examples of the monomer that gives the repeating unit a2 include, but are not limited to, those shown below. In the following formula, ^RA and R ¹² are the same as described above.

Examples of the acid unstable groups represented by ^{R 11} and R ¹² in the formulas (a1) and (a2) include those described in JP2013-80033 and JP2013-83821. ..

Typically, the acid unstable group includes those represented by the following formulas (AL-1) to (AL-3).

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

In the formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

In the formula (AL-2), R ^L3 and R ^L4 are independently hydrogen atoms or hydrocarbyl groups having 1 to 20 carbon atoms, and contain heteroatoms such as oxygen atom, sulfur atom, nitrogen atom and fluorine atom. You may be. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. As the hydrocarbyl group, an alkyl group having 1 to 20 carbon atoms is preferable. Further, any two of R ^L2, R ^L3 and R ^L4, may form a ring of 3 to 20 carbon atoms with the carbon atom or carbon and oxygen atoms to which it binds them combine with each other. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

In the formula (AL-3), ^RL5 , ^RL6 and ^RL7 are independently hydrocarbyl groups having 1 to 20 carbon atoms and contain heteroatoms such as oxygen atom, sulfur atom, nitrogen atom and fluorine atom. You may be. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. As the hydrocarbyl group, an alkyl group having 1 to 20 carbon atoms is preferable. Further, any two of R ^L5, R ^L6 and R ^L7, may form a ring of 3 to 20 carbon atoms with the carbon atom bonded these combined with each other. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

The base polymer may further contain a repeating unit b containing a phenolic hydroxy group as an adhesive group. Examples of the monomer that gives the repeating unit b include, but are not limited to, those shown below. In the following formula, ^RA is the same as described above.

The base polymer further includes, as other adhesive groups, a hydroxy group other than the 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. It may include a repeating unit c containing a group. Examples of the monomer that gives the repeating unit c include, but are not limited to, those shown below. In the following formula, ^RA is the same as described above.

The base polymer may further contain a repeating unit d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or derivatives thereof. Examples of the monomer that gives the repeating unit d include, but are not limited to, those shown below.

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

The base polymer may further 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 a repeating unit f1) and a repeating unit represented by the following formula (f2) (hereinafter, also referred to as a repeating unit f2). And a repeating unit represented by the following formula (f3) (hereinafter, also referred to as a repeating unit f3) can be mentioned. The repeating units f1 to f3 can be used alone or in combination of two or more.

In formulas (f1) to (f3), ^RA is independently a hydrogen atom or a methyl group. Z ¹ is a single bond, a phenylene ^{group, -O-Z 11 -, -} C (= O) -O-Z 11 - or -C (= O) -NH-Z 11 - a and, Z ¹¹ is carbon It is an aliphatic hydrocarbylene group or a phenylene group of the number 1 to 6, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z ² is a single ^{bond, -Z 21 -C (= O)} -O -, - Z 21 -O- or ^{-Z 21 -O-C (= O} ) - and is, Z ²¹ is 1 to carbon atoms It is 12 saturated hydrocarbylene groups and may contain a carbonyl group, an ester bond or an ether bond. Z ³ is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene ^{group, -O-Z 31 -, -} C (= O) -O-Z 31 - or -C (= O) -NH- Z ³¹ - a and, Z ³¹ 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, a carbonyl group, an ester bond , Ether bond or hydroxy group may be contained. The aliphatic hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbylene group may be linear, branched or cyclic.

In formulas (f1) to (f3), R ^{21 to} R ²⁸ are hydrocarbyl groups having 1 to 20 carbon atoms which may independently contain heteroatoms. 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, preferably 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, preferably an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Can be mentioned. In addition, some or all of the hydrogen atoms of these groups are saturated hydrocarbyl groups having 1 to 10 carbon atoms, halogen atoms, trifluoromethyl groups, cyano groups, nitro groups, hydroxy groups, mercapto groups and 1 to 10 carbon atoms. May be substituted with a saturated hydrocarbyloxy group of, a saturated hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms or a hydrocarbylcarbonyloxy group having 2 to 10 carbon atoms, and some of the carbon atoms of these groups are carbonyl groups, It may be substituted with an ether bond or an ester bond. Further, ^{any two of R 23} , R ²⁴ and R ²⁵ or any two of R ²⁶ , R ²⁷ and R ²⁸ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. At this time, the ring is the same as that exemplified as the ring that can be formed together with the sulfur atom to which ^two R 2s are bonded and these are bonded when r = 1 in the description of the formula (1). Can be mentioned.

In formula (f2), A ¹ is a hydrogen atom or a trifluoromethyl group.

Wherein (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, triflate ion, 1,1,1-trifluoroethanesulfonate ion, fluoroalkylsulfonate ion such as nonafluorobutane sulfonate ion, and the like. Tosylate ion, benzene sulfonate ion, 4-fluorobenzene sulfonate ion, aryl sulfonate ion such as 1,2,3,4,5-pentafluorobenzene sulfonate ion, alkyl sulfonate ion such as mesilate ion, butane sulfonate ion, bis Methyl ions such as (trifluoromethylsulfonyl) imide ion, bis (perfluoroethylsulfonyl) imide ion, bis (perfluorobutylsulfonyl) imide ion, tris (trifluoromethylsulfonyl) methide ion, tris (perfluoroethylsulfonyl) methide ion, etc. Can be mentioned.

Further, as the non-nucleophilic opposed ion, a sulfonic acid ion in which the α-position represented by the following formula (f1-1) is replaced with a fluorine atom and the α-position represented by the following formula (f1-2) are further used. Examples thereof include a sulfonic acid ion substituted with a fluorine atom and the β-position substituted with a trifluoromethyl group.

In the formula (f1-1), R ³¹ is a hydrogen atom, a hydrocarbyl group having 1 to 20 carbon atoms, and 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 those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the 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 2 to 30 carbon atoms, and contains an ether bond, an ester bond, a carbonyl group or a lactone ring. You may. The hydrocarbyl moiety of the hydrocarbyl group and the hydrocarbylcarbonyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those similar to those exemplified as the hydrocarbyl group represented by ^{R 5} in the formula (1A').

Examples of the cation of the monomer giving the repeating unit f1 include, but are not limited to, those shown below. In the following formula, ^RA is the same as described above.

Specific examples of the cation of the monomer giving the repeating unit f2 or f3 include the sulfonium cation described in JP-A-2017-219836.

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

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

By binding an acid generator to the polymer main chain, acid diffusion can be reduced and deterioration of resolution due to blurring of acid diffusion can be prevented. In addition, the LWR or CDU is improved by uniformly dispersing the acid generator.

The base polymer for positive resist materials requires repeating units a1 or a2 containing acid-labile groups. In this case, the content ratios of the repeating units a1, a2, b, c, d, e and f are 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 are preferable, and 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 is more preferable, 0≤a1≤0.8, 0≤a2≤0.8, 0.1≤a1 + a2≤0.8, 0≤b≤0.75, 0≤c≤0.75, More preferably, 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. Further, a1 + a2 + b + c + d + e + f = 1.0.

On the other hand, the base polymer for negative resist materials does not necessarily require an acid-labile group. Examples of such a base polymer include a repeating unit b and, if necessary, a repeating unit c, d, e and / or f. The content ratio of these repeating units is preferably 0 <b ≦ 1.0, 0 ≦ c ≦ 0.9, 0 ≦ d ≦ 0.8, 0 ≦ e ≦ 0.8, and 0 ≦ f ≦ 0.5. , 0.2 ≦ b ≦ 1.0, 0 ≦ c ≦ 0.8, 0 ≦ d ≦ 0.7, 0 ≦ e ≦ 0.7 and 0 ≦ f ≦ 0.4, more preferably 0.3 ≦ More preferably, 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. Further, b + c + d + e + f = 1.0.

In order to synthesize the base polymer, for example, the above-mentioned monomer giving the repeating unit may be heated by adding a radical polymerization initiator in an organic solvent to carry out the polymerization.

Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane and the like. As the polymerization initiator, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate) ), Benzoyl peroxide, lauroyl peroxide and the like. The temperature at the time of polymerization is preferably 50 to 80 ° C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

When copolymerizing a monomer containing a hydroxy group, the hydroxy group may be replaced with an acetal group which is easily deprotected with an acid such as an ethoxyethoxy group at the time of polymerization, and deprotection may be carried out with a weak acid and water after the polymerization. Alkali hydrolysis may be carried out after polymerization by substituting with an acetyl group, a formyl group, a pivaloyl group or the like.

When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene is used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group is deprotected by the alkali hydrolysis to remove hydroxystyrene or hydroxyvinyl. It may be naphthalene.

As the base for alkaline hydrolysis, aqueous ammonia, triethylamine and the like can be used. 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 has a polystyrene-equivalent weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent. It is 30,000. If Mw is too small, the resist material will be inferior in heat resistance, and if it is too large, the alkali solubility will decrease, and the tailing phenomenon will easily occur after pattern formation.

Further, when the molecular weight distribution (Mw / Mn) of the base polymer is wide, foreign matter may be seen on the pattern or the shape of the pattern may be deteriorated due to the presence of the polymer having a low molecular weight or a high molecular weight. There is a risk of As the pattern rule becomes finer, the influence of Mw and Mw / Mn tends to increase. Therefore, in order to obtain a resist material suitable for fine pattern dimensions, Mw / Mn of the base polymer is 1.0. It is preferable that the dispersion is as narrow as ~ 2.0, particularly 1.0 to 1.5.

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

[Other ingredients]
A resist material containing a sulfonium salt represented by the formula (1) and a base polymer, an organic solvent, a photoacid generator other than the sulfonium salt represented by the formula (1), a quencher, a surfactant, a dissolution inhibitor, By appropriately combining and blending a cross-linking agent or the like according to the purpose to form a positive resist material and a negative resist material, the dissolution rate of the base polymer in the developing solution is accelerated by a catalytic reaction in the exposed portion. It can be a positive resist material and a negative resist material with extremely high sensitivity. In this case, the dissolution contrast and resolution of the resist film are high, there is an exposure margin, the process adaptability is excellent, the pattern shape after exposure is good, and acid diffusion can be suppressed in particular, so that the difference in coarseness and density is small. From these facts, it is highly practical and can be made very effective as a resist material for VLSI. In particular, when a chemically amplified positive resist material utilizing an acid-catalyzed reaction is used, it can be made more sensitive and has more excellent properties, which is extremely useful.

Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, and methyl-2-n-pentyl ketone described in paragraphs [0144] to [0145] of JP-A-2008-111103, 3-methoxybutanol, and the like. Alcohols such as 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene Ethers such as glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, 3-ethoxypropion Examples thereof include esters such as ethyl acid, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, lactones such as γ-butyrolactone, and mixed solvents thereof.

In the resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass with respect to 100 parts by mass of the base polymer.

The resist material of the present invention may contain an acid generator other than the sulfonium salt represented by the formula (1) (hereinafter, referred to as other acid generator) as long as the effect of the present invention is not impaired. Examples of other acid generators include compounds that generate acids in response to active light or radiation (photoacid generators). The component of the photoacid generator may be any compound that generates an acid by irradiation with high energy rays, but an acid generator that generates a sulfonic acid, an imic acid or a methidoic acid is preferable. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethanes, N-sulfonyloxyimides, oxime-O-sulfonate type acid generators and the like. Specific examples of the acid generator are described in paragraphs [0122] to [0142] of JP-A-2008-111103. The content of the other acid generator is preferably 0 to 200 parts by mass, preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the base polymer.

The resist material of the present invention may contain a quencher. Examples of the quencher include conventional basic compounds. Conventional basic compounds include primary, secondary and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, and sulfonyl groups. Examples thereof include a nitrogen-containing compound having a hydroxy group, a nitrogen-containing compound having a hydroxyphenyl group, an alcoholic nitrogen-containing compound, amides, imides, and carbamates. In particular, primary, secondary and tertiary amine compounds described in paragraphs [0146] to [0164] of JP-A-2008-111103, particularly hydroxy groups, ether bonds, ester bonds, lactone rings, and the like. A cyano group, an amine compound having a sulfonic acid ester bond, a compound having a carbamate group described in Japanese Patent No. 3790649, and the like are preferable. By adding such a basic compound, for example, the diffusion rate of the acid in the resist film can be further suppressed or the shape can be corrected.

In addition, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids whose α-position is not fluorinated, which is described in JP-A-2008-158339. Sulfonic acid, imidic acid or methidoic acid with fluorinated α-position is required to deprotect the acid instability group of the carboxylic acid ester, but salt exchange with onium salt with fluorinated α-position. Releases a sulfonic acid or carboxylic acid whose α-position is not fluorinated. Sulfonic acids and carboxylic acids whose α-position is not fluorinated do not undergo a deprotection reaction and therefore function as a quencher.

Examples of such a quencher include a compound represented by the following formula (2) (an onium salt of a sulfonic acid whose α-position is not fluorinated) and a compound represented by the following formula (3) (carboxylic acid). Onium salt).

In the formula (2), R ¹⁰¹ is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a hetero atom, and the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is a fluorine atom. Or, those substituted with a fluoroalkyl group are excluded.

The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group and n-. Alkyl groups such as octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl Cyclic saturated hydrocarbyl group such as group, norbornyl group, tricyclo [5.2.1.10 ^2,6 ] decanyl group, adamantyl group, adamantylmethyl group; alkenyl group includes vinyl group, allyl group, propenyl group, butenyl group. Alkenyl groups such as groups and hexenyl groups; cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl groups; phenyl groups, naphthyl groups, alkylphenyl groups (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group) , 4-Ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), Dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), Aryl groups such as alkylnaphthyl groups (methylnaphthyl group, ethylnaphthyl group, etc.), dialkylnaphthyl groups (dimethylnaphthyl group, diethylnaphthyl group, etc.); heteroaryl groups such as thienyl group; benzyl group, 1-phenylethyl group, 2 -Examples include an aralkyl group such as a phenylethyl group.

Further, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms and halogen atoms, and some of the carbon atoms of these groups may be oxygen atoms. It may be substituted with a hetero atom-containing group such as a sulfur atom or a nitrogen atom, and as a result, a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, or a sulton ring. , Carous acid anhydride, haloalkyl group and the like may be contained. Hydrocarbyl groups containing heteroatoms include 4-hydroxyphenyl group, 4-methoxyphenyl group, 3-methoxyphenyl group, 2-methoxyphenyl group, 4-ethoxyphenyl group, 4-tert-butoxyphenyl group and 3-tert. -Alkoxyphenyl group such as butoxyphenyl group; alkoxyphenyl group such as methoxynaphthyl group, ethoxynaphthyl group, n-propoxynaphthyl group, n-butoxynaphthyl group; dialkoxynaphthyl group such as dimethoxynaphthyl group and diethoxynaphthyl group; An aryloxoalkyl group such as a 2-aryl-2-oxoethyl group such as a 2-phenyl-2-oxoethyl group, a 2- (1-naphthyl) -2-oxoethyl group, and a 2- (2-naphthyl) -2-oxoethyl group. And so on.

In formula (3), R ¹⁰² is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. Examples of the hydrocarbyl group represented by R ¹⁰² include those similar to those exemplified as the hydrocarbyl group represented by ^{R 101.} In addition, as other specific examples, a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, 2,2,2-trifluoro-1- (tri). Fluoromethyl) Fluorin-containing alkyl groups such as -1-hydroxyethyl group; Fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group can also be mentioned.

In formulas (2) and (3), Mq ⁺ is an onium cation.

As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (4) can also be preferably used.

In formula (4), R ²⁰¹ may have a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a part or all of a hydrogen atom substituted with a halogen atom. Saturated hydrocarbyl groups with 1 to 6 carbon atoms, saturated hydrocarbyloxy groups with 1 to 6 carbon atoms, saturated hydrocarbylcarbonyloxy groups with 2 to 6 carbon atoms, saturated hydrocarbylsulfonyloxy groups with 1 to 4 carbon atoms, or -NR ^201A- C (= O) -R ^201B or -NR ^201A- C (= O) -O-R ^201B . R ^201A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^201B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. L ^A is a (z + 1) -valent linking group of a single bond or a C 1-20 ether bond, a carbonyl group, an ester bond, an amide bond, sultone ring, lactam ring, carbonate group, halogen atom, hydroxy group, and It may contain at least one selected from carboxy groups. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group and saturated hydrocarbylsulfonyloxy group may be linear, branched or cyclic. When y and / or z are 2 or more, each R ²⁰¹ may be the same as or different from each other.

In formula (4), R ²⁰² , R ²⁰³ and R ²⁰⁴ are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or a hetero atom. be. 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, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Further, a part or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sulton group, a sulfone group or a sulfonium salt-containing group. , Some of the carbon atoms of these groups may be substituted with ether bonds, ester bonds, carbonyl groups, amide bonds, carbonate groups or sulfonic acid ester bonds. Further, ^{any two of R 202} , R ²⁰³ and R ²⁰⁴ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

In equation (4), x is an integer of 1-5. y is an integer from 0 to 3. z is an integer of 1 to 3.

Specific examples of the compound represented by the formula (4) include those described in JP-A-2017-219836. Iodine absorbs EUV with a wavelength of 13.5 nm so much that secondary electrons are generated during exposure, and the energy of the secondary electrons is transferred to the acid generator, which promotes the decomposition of the quencher. Can improve the sensitivity.

Further, as the quencher, the polymer type quencher described in JP-A-2008-239918 can be mentioned. This enhances the rectangularity of the resist film after patterning by orienting it on the surface of the resist film after coating. The polymer-type quencher also has the effect of preventing the film from being reduced and the pattern top from being rounded when a protective film for immersion exposure is applied.

When the resist material of the present invention contains a quencher, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass with respect to 100 parts by mass of the base polymer.

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

When the resist material of the present invention is of the positive type, the difference in dissolution rate between the exposed portion and the unexposed portion can be further increased by adding a dissolution inhibitor, and the resolution can be further improved. .. As the dissolution inhibitor, the hydrogen atom of the phenolic hydroxy group of a compound having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800 and containing two or more phenolic hydroxy groups in the molecule is acid. A compound in which the hydrogen atom of the carboxy group is replaced by an unstable group at a ratio of 0 to 100 mol% as a whole, or a compound containing a carboxy group in the molecule, and a hydrogen atom of the carboxy group is replaced by an acid unstable group in an average ratio of 50 to 100 mol% as a whole. Examples thereof include compounds substituted with. Specific examples thereof include bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantancarboxylic acid, hydroxy group of cholic acid, and compounds in which the hydrogen atom of the carboxy group is replaced with an acid unstable group. For example, it is described in paragraphs [0155] to [0178] of JP-A-2008-122932.

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

On the other hand, when the resist material of the present invention is a negative type, a negative pattern can be obtained by reducing the dissolution rate of the exposed portion by adding a cross-linking agent. The cross-linking agent includes an epoxy compound, a melamine compound, a guanamine compound, a glycoluril compound or a urea compound, an isocyanate compound, and an azide compound substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group. , Compounds containing a double bond such as an alkenyl ether group, and the like. These may be used as additives or may be introduced as pendant groups in the polymer side chain. Further, a compound containing a hydroxy group can also be used as a cross-linking agent.

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

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

Examples of the guanamine compound include a compound in which 1 to 4 methylol groups of tetramethylol guanamine, tetramethoxymethyl guanamine, and tetramethylol guanamine are methoxymethylated or a mixture thereof, and one of tetramethoxyethyl guanamine, tetraacyloxyguanamine, and tetramethylol guanamine. Examples thereof include a compound in which ~ 4 methoxyl groups are acyloxymethylated, or a mixture thereof.

Examples of the glycol uryl compound include tetramethylol glycol uryl, tetramethoxyglycol uryl, tetramethoxymethyl glycol uryl, and a compound in which 1 to 4 methylol groups of tetramethylol glycol uryl are methoxymethylated or a mixture thereof, and methylol of tetramethylol glycol uryl. Examples thereof include a compound in which 1 to 4 groups are acyloxymethylated or a mixture thereof. Examples of the urea compound include tetramethylol urea, tetramethoxymethylurea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, or a mixture thereof, and tetramethoxyethylurea.

Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate and the like.

Examples of the azide compound include 1,1'-biphenyl-4,4'-bis azide, 4,4'-methylidene bis azide, and 4,4'-oxybis azide.

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

When the resist material of the present invention is a negative resist material, the content of the cross-linking agent is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass with respect to 100 parts by mass of the base polymer. The cross-linking agent may be used alone or in combination of two or more.

The resist material of the present invention may contain a water repellency improver for improving the water repellency of the resist surface after spin coating. The water repellency improver can be used for immersion lithography without using a top coat. As the water repellency improving agent, a polymer compound containing an alkyl fluoride group, a polymer compound containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue having a specific structure, or the like is preferable. Those exemplified in JP-A-2007-297590, JP-A-2008-111103 and the like are more preferable. The water repellency improver needs to be dissolved 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 a developing solution. As a water repellency improving agent, a polymer compound containing a repeating unit containing an amino group or an amine salt is highly effective in preventing the evaporation of the acid in PEB and preventing the opening defect of the hole pattern after development. When the resist material of the present invention contains a water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more.

Acetylene alcohols can also be blended with the resist material of the present invention. Examples of the acetylene alcohols include those described in paragraphs [0179] to [0182] of JP-A-2008-122932. When the resist material of the present invention contains acetylene alcohols, the content thereof is preferably 0 to 5 parts by mass with respect to 100 parts by mass of the base polymer.

[Pattern formation method]
When the resist material of the present invention is used for manufacturing various integrated circuits, known lithography techniques can be applied.

For example, the resist material of the present invention can be used as a substrate for manufacturing integrated circuits (Si, SiO ₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for manufacturing mask circuits (Cr, CrO). , CrON, MoSi ₂ , SiO _2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc. so that the coating film thickness is 0.01 to 2 μm. do. This is prebaked on a hot plate at preferably 60 to 150 ° C. for 10 seconds to 30 minutes, more preferably 80 to 120 ° C. for 30 seconds to 20 minutes to form a resist film.

The resist film is then exposed to high energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation and the like. When ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. are used as the high-energy rays, an exposure amount is used by using a mask for forming a target pattern. Is preferably about 1 to 200 mJ / cm ² , and more preferably about 10 to ^{100 mJ / cm 2.} When using the EB as the high-energy radiation, the exposure amount is preferably 0.1~100μC / cm ^2, more preferably about a mask for forming a pattern of direct or object at about 0.5~50μC / cm ² Draw using. The resist material of the present invention is particularly suitable for fine patterning by KrF excimer laser light, ArF excimer laser light, EB, EUV, X-ray, soft X-ray, γ-ray, and synchrotron radiation among high-energy rays. It is particularly suitable for fine patterning by EB or EUV.

After the exposure, PEB may be carried out on a hot plate at preferably 60 to 150 ° C. for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C. for 30 seconds to 20 minutes.

After exposure or PEB, 0.1 to 10% by mass, preferably 2 to 5% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutyl Using a developing solution of an alkaline aqueous solution such as ammonium hydroxide (TBAH), the dipping method, the puddle method, the spray method, etc. are usually used for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes. By developing the resist film exposed by the method, a desired pattern is formed. In the case of a positive resist material, the portion irradiated with light is dissolved in the developing solution, the portion not exposed is not dissolved, and a desired positive pattern is formed on the substrate. The negative resist material is the opposite of the positive resist material, that is, the light-irradiated portion is insoluble in the developer and the unexposed portion is soluble.

Negative development to obtain a negative pattern by organic solvent development can also be performed using a positive resist material containing a base polymer containing an acid unstable group. The developing solution used at this time is 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutylketone, methylcyclohexanone, acetphenone, methylacetphenone, 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 pentate, Methyl crotonate, Ethyl crotonate, 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, 2-phenylethyl acetate and the like. These organic solvents can be used alone or in admixture of two or more.

Rinse at the end of development. As the rinsing solution, a solvent that is miscible with the developing solution and does not dissolve the resist film is preferable. As such a solvent, an alcohol having 3 to 10 carbon atoms, an ether compound having 8 to 12 carbon atoms, an alkane having 6 to 12 carbon atoms, an alkene, an alkyne, and an aromatic solvent are preferably used.

Specifically, the 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, and the like. 3-Pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol , 3-Hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pen Tanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl Examples thereof include -1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol and the like.

Examples of the ether compound 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, and di-tert-pentyl. Examples include 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 and the like. Be done. Examples of the alkene having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene and the like. Examples of the alkyne having 6 to 12 carbon atoms include hexyne, heptin, octyne and the like.

Examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene and the like.

By rinsing, it is possible to reduce the occurrence of the resist pattern collapse and defects. In addition, rinsing is not always essential, and the amount of solvent used can be reduced by not rinsing.

The developed hole pattern or trench pattern can also be shrunk by thermal flow, RELACS technology or DSA technology. A shrink agent is applied onto the hole pattern, and the diffusion of the acid catalyst from the resist layer during baking causes cross-linking of the shrink agent on the surface of the resist, and the shrink agent adheres to the side wall 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 reducing the hole pattern.

Hereinafter, the present invention will be specifically described with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The structures of the acid generators PAG1 to PAG23 used in the resist material are shown below. PAG1 was synthesized by an esterification reaction of p-hydroxyphenyldiphenylsulfonium salt with 2-iodoacetate chloride. PAG2 to PAG23 were synthesized by an esterification reaction similar to that of PAG1.

[Synthesis Example] Synthesis of Base Polymers (Polymers 1 to 4) Each monomer is combined, copolymerized in THF as a solvent, crystallized in methanol, washed with hexane repeatedly, and then isolated and dried. Then, a base polymer (polymers 1 to 4) having the composition shown below was obtained. The composition of the obtained base polymer ^{was confirmed by 1} H-NMR, and Mw and Mw / Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[Examples 1 to 26, Comparative Examples 1 to 5] Preparation of resist material and evaluation thereof (1) Preparation of resist material Tables 1 to 3 in a solvent in which 100 ppm of PolyFox PF-636 manufactured by Omniova Co., Ltd. was dissolved as a surfactant. A solution in which each component was dissolved with the composition shown in (1) was filtered through a filter having a size of 0.2 μm to prepare a resist material. The resist materials of Examples 1 to 13, 15 to 26 and Comparative Examples 1 to 4 are of the positive type, and the resist materials of Examples 14 and 5 are of the negative type.

In Tables 1 to 3, each component is as follows.
Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)
GBL (γ-butyrolactone)
CyH (cyclohexanone)
PGME (Propylene Glycol Monomethyl Ether)
DAA (diacetone alcohol)

Acid generators for comparative examples: cPAG1 to cPAG4 (see structural formula below)

Quenchers 1-3 (see structural formula below)

(2) EUV lithography evaluation Each resist material shown in Tables 1 to 3 is Si formed by Shin-Etsu Chemical Co., Ltd. silicon-containing spin-on hard mask SHB-A940 (silicon content is 43% by mass) with a film thickness of 20 nm. A resist film having a film thickness of 50 nm was prepared by spin coating on a substrate and prebaking at 105 ° C. for 60 seconds using a hot plate. This is exposed to EUV using ASML's EUV scanner NXE3300 (NA0.33, σ0.9 / 0.6, quadrupole illumination, wafer top dimension pitch 46 nm, + 20% bias hole pattern mask), and hot plate. PEB was carried out at the temperatures shown in Tables 1 to 3 above for 60 seconds, and development was carried out with a 2.38 ASML TMAH aqueous solution for 30 seconds. In Examples 1 to 13, 15 to 26 and Comparative Examples 1 to 4, the dimensions were 23 nm. As a hole pattern, a dot pattern having a size of 26 nm was obtained in Example 14 and Comparative Example 5.
Using a length measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation, the exposure amount when the hole and dot dimensions are formed at 23 nm and 26 nm, respectively, is measured and used as the sensitivity. The dimensions of 50 holes or dots were measured, and the dimensional variation (CDU, 3σ) was determined. The results are also shown in Tables 1 to 3.

From the results shown in Tables 1 to 3, it was found that the resist material of the present invention containing the sulfonium salt represented by the formula (1) as an acid generator has high sensitivity and good CDU.

Claims (14)

A resist material containing an acid generator containing a sulfonium salt represented by the following formula (1).

(In the equation, k, m and n are each independently an integer of 1 to 3. p is 0 or 1. q is an integer of 0 to 4. r is an integer of 1 to 3. It is an integer.
X ^BI is an iodine atom or a bromine atom.
R ^al is a (k + 1) -valent aliphatic hydrocarbon group having 1 to 20 carbon atoms, and is an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, a carbonate group, or a halogen atom other than an iodine atom. , At least one selected from an aryl group having 6 to 12 carbon atoms, a hydroxy group and a carboxy group may be contained.
X ¹ is a single bond, an ether bond, an ester bond, an amide bond, a carbonyl group or a carbonate group.
X ² is a single bond or a (m + 1) valent hydrocarbon group having 1 to 20 carbon atoms, other than an ether bond, a carbonyl group, an ester bond, an amide bond, a sulton ring, a lactam ring, a carbonate group, and an iodine atom. It may contain at least one selected from a halogen atom, a hydroxy group and a carboxy group.
X ³ is a single bond, ether bond or ester bond.
R ¹ is a saturated hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, an ester bond or a hydroxy group.
R ² is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. When r = 1, the two R ^2s may be the same or different from each other and may be bonded to each other to form a ring with the sulfur atoms to which they are bonded.
R ³ is a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an amino group, or a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, 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 hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, and a saturated hydrocarbyl group having 2 to 20 carbon atoms, which may contain an ether bond. It is an oxycarbonyl group or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms.
X ^- is a non-nucleophilic opposing ion. ) The resist material according to claim 1, wherein the non-nucleophilic counter ion is a fluorinated sulfonic acid ion, a fluorinated imidate ion, or a fluorinated methideate ion. The resist material according to claim 1 or 2, further comprising a base polymer. The resist material according to claim 3, 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, ^RA is a hydrogen atom or a methyl group, respectively.
Y ¹ is a linking group having 1 to 12 carbon atoms having a single bond, a phenylene group or a naphthylene group, or an ester bond, an ether bond or a lactone ring.
Y ² is a single bond, an ester bond or an amide bond.
Y ³ is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are acid-labile groups.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, and 2 carbon atoms. It is a saturated hydrocarbylcarbonyloxy group of ~ 7 or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms.
R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and a part of the carbon atom thereof may be substituted with an ether bond or an ester bond.
a is 1 or 2. b is an integer from 0 to 4. ) The resist material according to claim 4, which is a chemically amplified positive resist material. The resist material according to claim 3, wherein the base polymer does not contain an acid unstable group. The resist material according to claim 6, which is a chemically amplified negative resist material. The resist material according to any one of claims 1 to 7, wherein the base polymer contains at least one selected from the repeating units represented by the following formulas (f1) to (f3).

(In the formula, ^RA is a hydrogen atom or a methyl group, respectively.
Z ¹ is a single bond, a phenylene ^{group, -O-Z 11 -, -} C (= O) -O-Z 11 - or -C (= O) -NH-Z 11 - a and, Z ¹¹ is carbon It is an aliphatic hydrocarbylene group or a phenylene group of the number 1 to 6, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group.
Z ² is a single ^{bond, -Z 21 -C (= O)} -O -, - Z 21 -O- or ^{-Z 21 -O-C (= O} ) - is. Z ²¹ is a saturated hydrocarbylene group having 1 to 12 carbon atoms and may contain a carbonyl group, an ester bond or an ether bond.
Z ³ is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene ^{group, -O-Z 31 -, -} C (= O) -O-Z 31 - or -C (= O) -NH- Z ³¹ −. Z ³¹ is a phenylene group substituted with an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group having 1 to 6 carbon atoms, and is a carbonyl group, an ester bond, an ether bond, or a hydroxy group. May include.
R ^{21 to} R ²⁸ are hydrocarbyl groups having 1 to 20 carbon atoms, which may independently contain heteroatoms. Further, ^{any two of R 23} , R ²⁴ and R ²⁵ or any two of R ²⁶ , R ²⁷ and R ²⁸ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
A ¹ is a hydrogen atom or a trifluoromethyl group.
M ^- is a non-nucleophilic opposing ion. ) The resist material according to any one of claims 1 to 8, further comprising an organic solvent. The resist material according to any one of claims 1 to 9, further comprising a quencher. The resist material according to any one of claims 1 to 10, further comprising a surfactant. A step of forming a resist film on a substrate using the resist material according to any one of claims 1 to 11, a step of exposing the resist film with high energy rays, and a developing solution for exposing the exposed resist film. A pattern forming method including a step of developing using. The pattern forming method according to claim 12, wherein the high-energy ray is an ArF excimer laser light having a wavelength of 193 nm or a KrF excimer laser light having a wavelength of 248 nm. The pattern forming method according to claim 12, wherein the high energy ray is an electron beam or extreme ultraviolet rays having a wavelength of 3 to 15 nm.