JP2023152629A - Positive resist material and pattern forming process - Google Patents

Abstract

To provide a positive resist material that exhibits sensitivity and resolution that surpass those of the conventional positive resist material, is small in edge roughness and dimensional variation, and is good in pattern shape after exposure, and a pattern forming process.SOLUTION: A positive resist material comprises a base polymer comprising a repeat unit represented by the formula (a) [where R represents a specific group, including a phenyl group and an unsaturated aliphatic hydrocarbyl group].SELECTED DRAWING: None

Description

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

As LSIs become more highly integrated and faster, pattern rules are rapidly becoming finer. This is because 5G high-speed communications and artificial intelligence (AI) are becoming more widespread, and high-performance devices are needed to process them. As the most advanced miniaturization technology, 5 nm node devices are being mass-produced using extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm. Furthermore, studies using EUV lithography are also underway for next-generation 3nm node and next-generation 2nm node devices.

As miniaturization progresses, image blurring due to acid diffusion has become a problem. In order to ensure the resolution of fine patterns with a dimension size of 45 nm or more, it has been proposed that it is important not only to improve dissolution contrast, which has been proposed in the past, but also to control acid diffusion (Non-patent Document 1). However, chemically amplified resist materials increase sensitivity and contrast by acid diffusion, so if you try to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the time, the sensitivity and contrast will increase. and the contrast decreases significantly.

A triangle trade-off relationship between sensitivity, resolution, and edge roughness (LER, LWR) is shown. In order to improve resolution, it is necessary to suppress acid diffusion, but as the acid diffusion distance becomes shorter, sensitivity decreases.

It is effective to suppress acid diffusion by adding an acid generator that generates bulky acid. Therefore, it has been proposed that a repeating unit derived from an onium salt having a polymerizable unsaturated bond be included in a polymer. At this time, the polymer also functions as an acid generator (polymer bound acid generator). Patent Document 1 proposes a sulfonium salt or an iodonium salt having a polymerizable unsaturated bond that generates a specific sulfonic acid. Patent Document 2 proposes a sulfonium salt in which a sulfonic acid is directly linked to the main chain.

A triangle trade-off relationship between sensitivity, resolution, and edge roughness is shown. In order to improve resolution, it is necessary to suppress acid diffusion, but as the acid diffusion distance becomes shorter, sensitivity decreases.

The structure of acid-labile groups in the base polymer is important as a component that contributes to the performance of positive resist materials. Here, a tertiary ester type acid-labile group bonded to an aromatic group substituted with a fluorine atom has been proposed (Patent Documents 3 and 4). Tertiary ester-type acid-labile groups that bind to aromatic groups have extremely high reactivity for elimination with acids, making it difficult to control acid diffusion; however, it is now possible to introduce fluorine atoms into aromatic groups. This suppresses the elimination reactivity to an appropriate level.

On the other hand, the tertiary ester type acid-labile group having an olefin, as exemplified in paragraph [0036] of Patent Document 5, has very high elimination reactivity with acids, so it has been difficult to control acid diffusion. In addition, the secondary ester type acid-labile group having an olefin as exemplified in paragraph [0188] of Patent Document 6 has a problem in that high dissolution contrast cannot be obtained because the acid-induced elimination reactivity is low. Ta.

JP2006-045311A Japanese Patent Application Publication No. 2006-178317 Patent No. 3832564 Patent No. 5655754 Japanese Patent Application Publication No. 2001-302728 JP2022-025610A

SPIE Vol. 6520 65203L-1 (2007)

The present invention was made in view of the above-mentioned circumstances, and includes a positive resist material that has higher sensitivity and resolution than conventional positive resist materials, has small edge roughness and dimensional variations, and has a good pattern shape after exposure. and a pattern forming method.

The inventors of the present invention have conducted extensive studies in order to obtain a positive resist material that has the high resolution that has been demanded in recent years and has small edge roughness and dimensional variations, and has found that this requires the shortest possible acid diffusion distance. At this time, a problem arises in that the resolution of two-dimensional patterns such as hole patterns decreases due to a decrease in sensitivity and a decrease in dissolution contrast, but the problem is that the resolution of two-dimensional patterns such as hole patterns decreases due to the decrease in sensitivity and the decrease in dissolution contrast. It was discovered that by using a polymer containing a repeating unit having a tertiary ester group with an aromatic group as the base polymer, it is possible to increase the dissolution contrast while simultaneously minimizing the acid diffusion distance. It was found that it is extremely effective when used as a base polymer for mold resist materials.

Furthermore, in order to improve the dissolution contrast, by introducing into the base polymer a repeating unit in which the hydrogen atom of a carboxyl group or a phenolic hydroxyl group is replaced with an acid-labile group, high sensitivity and alkali dissolution rate before and after exposure can be achieved. Very high contrast, highly effective in suppressing acid diffusion, high resolution, and good pattern shape, edge roughness, and dimensional uniformity (CDU) after exposure, especially fine patterns for VLSI manufacturing or photomasks. The present invention was completed based on the discovery that a positive resist material suitable as a forming material can be obtained.

［式中、Ｒ^Aは、水素原子又はメチル基である。
Ｘ¹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、エーテル結合及び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。
Ｒは、下記式（ａ１）で表される基である。

（式中、Ｒ¹は、酸素原子を含んでいてもよい直鎖状又は分岐状の炭素数１～６の脂肪族ヒドロカルビル基であり、Ｒ²は、酸素原子を含んでいてもよい直鎖状又は分岐状の炭素数２～６の不飽和脂肪族ヒドロカルビル基である。また、Ｒ¹とＲ²とが、互いに結合して、これらが結合する炭素原子と共に炭素数５～１２の環を形成してもよい。
Ｒ³は、ハロゲン原子、シアノ基、フッ素原子で置換された炭素数１～４のアルキル基、フッ素原子で置換された炭素数１～４のアルコキシ基又はフッ素原子で置換された炭素数１～４のアルキルチオ基である。
Ｒ⁴は、炭素数１～４のアルキル基である。
ｍは、１～５の整数であり、ｎは、０～４の整数である。ただし、１≦ｍ＋ｎ≦５である。
破線は、結合手である。）］
２．前記ベースポリマーが、更に、カルボキシ基の水素原子が式（ａ１）で表される基以外の酸不安定基で置換された繰り返し単位及びフェノール性ヒドロキシ基の水素原子が酸不安定基で置換された繰り返し単位から選ばれる少なくとも１種を含む１のポジ型レジスト材料。
３．カルボキシ基の水素原子が式（ａ１）で表される基以外の酸不安定基で置換された繰り返し単位が、下記式（ｂ１）で表されるものであり、フェノール性ヒドロキシ基の水素原子が酸不安定基で置換された繰り返し単位が、下記式（ｂ２）で表されるものである２のポジ型レジスト材料。

（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、エーテル結合及び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、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は、式（ａ１）で表される基以外の酸不安定基である。
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－ＣＨ₂－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。）
４．前記ベースポリマーが、更に、ヒドロキシ基、カルボキシ基、ラクトン環、カーボネート結合、チオカーボネート結合、カルボニル基、環状アセタール基、エーテル結合、エステル結合、スルホン酸エステル結合、シアノ基、アミド結合、－Ｏ－Ｃ(＝Ｏ)－Ｓ－及び－Ｏ－Ｃ(＝Ｏ)－ＮＨ－から選ばれる密着性基を含む繰り返し単位を含むものである１～３のいずれかのポジ型レジスト材料。
５．前記ベースポリマーが、更に、下記式（ｄ１）～（ｄ３）のいずれかで表される繰り返し単位を含むものである１～４のいずれかのポジ型レジスト材料。

（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、若しくは炭素数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の脂肪族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、ハロゲン原子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及びＲ²⁴又はＲ²⁶及びＲ²⁷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。
Ｍ^-は、非求核性対向イオンである。）
６．更に、酸発生剤を含む１～５のいずれかのポジ型レジスト材料。
７．更に、有機溶剤を含む１～６のいずれかのポジ型レジスト材料。
８．更に、クエンチャーを含む１～７のいずれかのポジ型レジスト材料。
９．更に、界面活性剤を含む１～８のいずれかのポジ型レジスト材料。
１０．１～９のいずれかのポジ型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。
１１．前記高エネルギー線が、ｉ線、ＫｒＦエキシマレーザー光、ＡｒＦエキシマレーザー光、電子線（ＥＢ）又は波長３～１５ｎｍのＥＵＶである１０のパターン形成方法。 That is, the present invention provides the following positive resist material and pattern forming method.
1. A positive resist material containing a base polymer containing a repeating unit represented by the following formula (a).

[Wherein, R ^A is a hydrogen atom or a methyl group.
X ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and a lactone ring.
R is a group represented by the following formula (a1).

(In the formula, R ¹ is a linear or branched aliphatic hydrocarbyl group having 1 to 6 carbon atoms that may contain an oxygen atom, and R ² is a linear or branched aliphatic hydrocarbyl group that may contain an oxygen atom. It is a shaped or branched unsaturated aliphatic hydrocarbyl group having 2 to 6 carbon atoms.Also, R ¹ and R ² are bonded to each other to form a ring having 5 to 12 carbon atoms together with the carbon atoms to which they are bonded. may be formed.
R ³ is a halogen atom, a cyano group, an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms substituted with a fluorine atom, or an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom; 4 is an alkylthio group.
R ⁴ is an alkyl group having 1 to 4 carbon atoms.
m is an integer from 1 to 5, and n is an integer from 0 to 4. However, 1≦m+n≦5.
The broken lines are bonds. )]
2. The base polymer further comprises a repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group other than the group represented by formula (a1), and a repeating unit in which the hydrogen atom of the phenolic hydroxy group is substituted with an acid-labile group. 1. A positive resist material containing at least one type of repeating unit selected from repeating units.
3. A repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group other than the group represented by formula (a1) is represented by the following formula (b1), and the hydrogen atom of the phenolic hydroxy group is 2. A positive resist material according to 2, wherein the repeating unit substituted with an acid-labile group is represented by the following formula (b2).

(In the formula, R ^A is each independently a hydrogen atom or a methyl group.
Y ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and 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 is an acid-labile group other than the group represented by formula (a1).
R ¹² is 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, and some of its -CH ₂ - groups may be substituted with an ether bond or an ester bond.
a is 1 or 2. b is an integer from 0 to 4. However, 1≦a+b≦5. )
4. The base polymer further includes a hydroxy group, a carboxy group, a lactone ring, a carbonate bond, a thiocarbonate bond, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O- The positive resist material according to any one of 1 to 3, which contains a repeating unit containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-.
5. 5. The positive resist material according to any one of 1 to 4, wherein the base polymer further contains a repeating unit represented by any of the following formulas (d1) to (d3).

(In the formula, 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 is a carbonyl group, an ester bond, an ether bond, or a hydroxy group. May contain.
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 an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these; a carbonyl group, an ester bond, an ether bond, an iodine atom or a bromine atom; May contain.
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 is a carbonyl group, an ester bond, an ether bond, a halogen atom, or It may contain a hydroxy group.
R ²¹ to R ²⁸ each independently represent a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a hetero atom. Furthermore, 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 counterion. )
6. The positive resist material according to any one of 1 to 5, further comprising an acid generator.
7. Further, any one of positive resist materials 1 to 6 containing an organic solvent.
8. Further, any one of positive resist materials 1 to 7 containing a quencher.
9. The positive resist material according to any one of 1 to 8, further containing a surfactant.
10. A step of forming a resist film on a substrate using the positive resist material according to any one of 1 to 9, a step of exposing the resist film to high-energy radiation, and a step of treating the exposed resist film with a developer. A pattern forming method comprising:
11. 10. The pattern forming method according to 10, wherein the high-energy beam is i-line, KrF excimer laser light, ArF excimer laser light, electron beam (EB), or EUV with a wavelength of 3 to 15 nm.

The positive resist material of the present invention can improve the decomposition efficiency of the acid generator, so it has a high effect of suppressing acid diffusion, has high sensitivity, high resolution, and has a pattern shape and edge after exposure. Good roughness and CDU. Therefore, since it has these excellent properties, it has extremely high practicality, and is particularly useful as a fine pattern forming material for VLSI manufacturing or a photomask by EB writing, and a pattern forming material for EB or EUV exposure. The positive resist material of the present invention can be applied, for example, not only to lithography in the formation of semiconductor circuits, but also to the formation of mask circuit patterns, micromachines, and thin film magnetic head circuits.

[Positive resist material]
The positive resist material of the present invention contains a repeating unit represented by the following formula (a) (hereinafter also referred to as repeating unit a).

In formula (a), R ^A is a hydrogen atom or a methyl group. X ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and a lactone ring.

In formula (a), R is a group represented by the following formula (a1).

In formula (a1), R ¹ is a linear or branched aliphatic hydrocarbyl group having 1 to 6 carbon atoms which may contain an oxygen atom, and R ² may contain an oxygen atom. It is a linear or branched unsaturated aliphatic hydrocarbyl group having 2 to 6 carbon atoms. Further, R ¹ and R ² may be bonded to each other to form a ring having 5 to 12 carbon atoms together with the carbon atoms to which they are bonded. R ³ is a halogen atom, a cyano group, an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms substituted with a fluorine atom, or an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom; 4 is an alkylthio group. R ⁴ is an alkyl group having 1 to 4 carbon atoms. m is an integer from 1 to 5, and n is an integer from 0 to 4. However, 1≦m+n≦5. The broken lines are bonds.

The aliphatic hydrocarbyl group having 1 to 6 carbon atoms represented by R ¹ may be saturated or unsaturated, and specific examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, Alkyl groups having 1 to 6 carbon atoms such as isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group; vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, pentenyl group, hexenyl group Alkenyl groups having 2 to 6 carbon atoms such as; alkynyl groups having 2 to 6 carbon atoms such as ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, pentynyl group, hexynyl group; Specific examples of the unsaturated aliphatic hydrocarbyl group having 2 to 6 carbon atoms represented by R ² include those having 1 carbon number such as vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, pentenyl group, hexenyl group, etc. -6 alkenyl group; Examples include alkynyl groups having 1 to 6 carbon atoms such as ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, pentynyl group, and hexynyl group.

Examples of the ring having 5 to 12 carbon atoms that can be formed by R ¹ and R ² together with the carbon atoms to which they are bonded include a cyclopentene ring, a methylcyclopentene ring, a dimethylcyclopentene ring, an ethylcyclopentene ring, and an ethylmethylcyclopentene ring. , cyclohexene ring, methylcyclohexene ring, dimethylcyclohexene ring, ethylmethylcyclohexene ring, isopropylmethylcyclohexene ring, cycloheptene ring, and the like.

Examples of the halogen atom represented by R ³ include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

Examples of the alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom represented by R ³ include a trifluoromethyl group, a pentafluoroethyl group, a hexafluoroisopropyl group, and the like. Examples of the alkoxy group having 1 to 4 carbon atoms substituted with a fluorine atom include a trifluoromethoxy group, a pentafluoroethoxy group, and a hexafluoroisopropoxy group. Examples of the alkylthio group having 1 to 4 carbon atoms substituted with a fluorine atom include a trifluoromethylthio group.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ⁴ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group and tert-butyl group. It will be done.

Examples of the group represented by formula (a1) include, but are not limited to, those shown below. In addition, in the following formula, the broken line is a bond.

Monomers that provide the repeating unit represented by formula (a) include, but are not limited to, those shown below. In addition, in the following formula, R ^A and R are the same as above.

The repeating unit a has a tertiary ester group bonded to a double bond or triple bond and an aromatic group substituted with an electron-withdrawing group. Since such a tertiary ester group has a high effect of suppressing swelling in an alkaline developer, by using a base polymer containing the repeating unit a, a resist film with high dissolution contrast and low swelling characteristics can be obtained.

The base polymer is a repeating unit (hereinafter also referred to as repeating unit b1) in which the hydrogen atom of a carboxy group is substituted with an acid-labile group other than the group represented by formula (a1) in order to further enhance the dissolution contrast. and/or a repeating unit in which the hydrogen atom of a phenolic hydroxy group is substituted with an acid-labile group (hereinafter also referred to as repeating unit b2).

Examples of the repeating units b1 and b2 include those represented by the following formulas (b1) and (b2), respectively.

In formulas (b1) and (b2), R ^A is each independently a hydrogen atom or a methyl group. Y ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and 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 is an acid-labile group other than the group represented by formula (a1). R ¹² is 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, and some of its -CH ₂ - groups may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer from 0 to 4. However, 1≦a+b≦5.

Examples of monomers that provide the repeating unit b1 include, but are not limited to, those shown below. In addition, in the following formula, R ^A and R ¹¹ are the same as above.

Examples of monomers providing the repeating unit b2 include, but are not limited to, those shown below. In addition, in the following formula, R ^A and R ¹² are the same as above.

（式中、破線は、結合手である。） The acid-labile group represented by R ¹¹ or R ¹² can be selected from various types, and examples thereof include those represented by the following formulas (AL-1) to (AL-3).

(In the formula, the broken line is a bond.)

In formula (AL-1), c is an integer from 0 to 6. R ^L1 is a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms, a carbonyl group, an ether bond, or an ester A saturated hydrocarbyl group having 4 to 20 carbon atoms containing a bond, or a group represented by formula (AL-3). Note that the tertiary hydrocarbyl group means a group obtained by removing a hydrogen atom from a tertiary carbon atom of a hydrocarbon.

The tertiary hydrocarbyl group represented by R ^L1 may be saturated or unsaturated, and may be branched or cyclic. Specific examples include tert-butyl group, tert-pentyl group, 1,1-diethylpropyl group, 1-ethylcyclopentyl group, 1-butylcyclopentyl group, 1-ethylcyclohexyl group, 1-butylcyclohexyl group, 1- Examples include ethyl-2-cyclopentenyl group, 1-ethyl-2-cyclohexenyl group, and 2-methyl-2-adamantyl group. Examples of the trihydrocarbylsilyl group include trimethylsilyl group, triethylsilyl group, dimethyl-tert-butylsilyl group, and the like. The saturated hydrocarbyl group containing a carbonyl group, ether bond, or ester bond may be linear, branched, or cyclic, but cyclic is preferable, and specific examples include 3-oxocyclohexyl group, 4 -Methyl-2-oxooxan-4-yl group, 5-methyl-2-oxooxolan-5-yl group, 2-tetrahydropyranyl group, 2-tetrahydrofuranyl group and the like.

Examples of the acid labile group represented by formula (AL-1) include a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tert-pentyloxycarbonyl group, a tert-pentyloxycarbonylmethyl group, and a 1,1-diethyl group. Propyloxycarbonyl group, 1,1-diethylpropyloxycarbonylmethyl group, 1-ethylcyclopentyloxycarbonyl group, 1-ethylcyclopentyloxycarbonylmethyl group, 1-ethyl-2-cyclopentenyloxycarbonyl group, 1-ethyl-2 -cyclopentenyloxycarbonylmethyl group, 1-ethoxyethoxycarbonylmethyl group, 2-tetrahydropyranyloxycarbonylmethyl group, 2-tetrahydrofuranyloxycarbonylmethyl group, and the like.

（式中、破線は、結合手である。） Furthermore, examples of the acid-labile group represented by formula (AL-1) include groups represented by formulas (AL-1)-1 to (AL-1)-10 below.

(In the formula, the broken line is a bond.)

In formulas (AL-1)-1 to (AL-1)-10, c is the same as above. R ^L8 are each independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. R ^L9 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R ^L10 is a saturated hydrocarbyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

In formula (AL-2), R ^L2 and R ^L3 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and sec-butyl group. group, tert-butyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, n-octyl group and the like.

（式中、破線は、結合手である。） In formula (AL-2), R ^L4 is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 18 carbon atoms, and some of these hydrogen atoms are substituted with a hydroxy group, an alkoxy group, an oxo group, an amino group, an alkylamino group, etc. Good too. Examples of such substituted saturated hydrocarbyl groups include those shown below.

(In the formula, the broken line is a bond.)

R ^L2 and R ^L3 , R ^L2 and R ^L4 , or R ^L3 and R ^L4 may be bonded to each other to form a ring with the carbon atom to which they are bonded, or with a carbon atom and an oxygen atom, In this case, R ^L2 and R ^L3 , R ^L2 and R ^L4 , or R ^L3 and R ^L4 involved in ring formation are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. . The number of carbon atoms in the ring obtained by combining these is preferably 3 to 10, more preferably 4 to 10.

Among the acid-labile groups represented by the formula (AL-2), those represented by the following formulas (AL-2)-1 to (AL-2)-69 are linear or branched groups. These include, but are not limited to: In addition, in the following formula, the broken line is a bond.

Among the acid-labile groups represented by formula (AL-2), cyclic ones include tetrahydrofuran-2-yl group, 2-methyltetrahydrofuran-2-yl group, tetrahydropyran-2-yl group, 2- Examples include methyltetrahydropyran-2-yl group.

（式中、破線は、結合手である。） Furthermore, examples of acid-labile groups include groups represented by the following formula (AL-2a) or (AL-2b). The base polymer may be intermolecularly or intramolecularly crosslinked by the acid-labile group.

(In the formula, the broken line is a bond.)

In formula (AL-2a) or (AL-2b), R ^L11 and R ^L12 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 8 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Further, R ^L11 and R ^L12 may be bonded to each other to form a ring with the carbon atom to which they are bonded, and in this case, R ^L11 and R ^L12 each independently represent an alkane having 1 to 8 carbon atoms. It is a diyl group. R ^L13 are each independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. d and e are each independently an integer of 0 to 10, preferably an integer of 0 to 5, and f is an integer of 1 to 7, preferably an integer of 1 to 3.

In formula (AL-2a) or (AL-2b), L ^A is an (f+1) valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, or an (f+1) valent alicyclic group having 3 to 50 carbon atoms. A saturated hydrocarbon group, an (f+1) valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or a (f+1) valent heterocyclic group having 3 to 50 carbon atoms. In addition, a part of -CH ₂ - of these groups may be substituted with a group containing a hetero atom, and a part of the hydrogen atoms of these groups may be a hydroxy group, a carboxy group, an acyl group, or a fluorine atom. May be replaced. L ^A is preferably a saturated hydrocarbon group having 1 to 20 carbon atoms, such as a saturated hydrocarbylene group, a trivalent saturated hydrocarbon group, or a tetravalent saturated hydrocarbon group, or an arylene group having 6 to 30 carbon atoms. The saturated hydrocarbon group may be linear, branched, or cyclic. L ^B is -C(=O)-O-, -NH-C(=O)-O- or -NH-C(=O)-NH-.

（式中、破線は、結合手である。） Examples of the crosslinked acetal group represented by the formula (AL-2a) or (AL-2b) include groups represented by the following formulas (AL-2)-70 to (AL-2)-77.

(In the formula, the broken line is a bond.)

In formula (AL-3), R ^L5 , R ^L6 and R ^L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, and do not contain a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. It's okay to stay. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, Examples include six to ten aryl groups. Further, R ^L5 and R ^L6 , R ^L5 and R ^L7 , or R ^L6 and R ^L7 may be bonded to each other to form an alicyclic ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded. .

Examples of the group represented by formula (AL-3) include tert-butyl group, 1,1-diethylpropyl group, 1-ethylnorbornyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, and 1-isopropylcyclopentyl group. 1-methylcyclohexyl group, 2-(2-methyl)adamantyl group, 2-(2-ethyl)adamantyl group, tert-pentyl group, and the like.

（式中、破線は、結合手である。） Further, examples of the group represented by formula (AL-3) include groups represented by the following formulas (AL-3)-1 to (AL-3)-19.

(In the formula, the broken line is a bond.)

In formulas (AL-3)-1 to (AL-3)-19, R ^L14 is each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms or an aryl group having 6 to 20 carbon atoms. R ^L15 and R ^L17 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. R ^L16 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Furthermore, the aryl group is preferably a phenyl group or the like. R ^F is a fluorine atom or a trifluoromethyl group. g is an integer from 1 to 5.

（式中、破線は、結合手である。） Furthermore, examples of acid-labile groups include groups represented by the following formula (AL-3)-20 or (AL-3)-21. The polymer may be intramolecularly or intermolecularly crosslinked by the acid-labile groups.

(In the formula, the broken line is a bond.)

In formulas (AL-3)-20 and (AL-3)-21, R ^L14 is the same as above. R ^L18 is a (h+1) valent saturated hydrocarbylene group having 1 to 20 carbon atoms or a (h+1) valent arylene group having 6 to 20 carbon atoms, and contains a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. May contain. The saturated hydrocarbylene group may be linear, branched, or cyclic. h is an integer from 1 to 3.

Examples of monomers that provide a repeating unit containing an acid-labile group represented by formula (AL-3) include (meth)acrylic acid esters containing an exo structure represented by formula (AL-3)-22 below. It will be done.

In formula (AL-3)-22, R ^A is the same as above. R ^Lc1 is a saturated hydrocarbyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. R ^Lc2 to R ^Lc11 each independently represent a hydrocarbyl group having 1 to 15 carbon atoms and which may contain a hydrogen atom or a hetero atom. Examples of the heteroatoms include oxygen atoms and the like. Examples of the hydrocarbyl group include an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 15 carbon atoms, and the like. R ^Lc2 and R ^Lc3 , R ^Lc4 and R ^Lc6 , R ^Lc4 and R ^Lc7 , R ^Lc5 and R ^Lc7 , R ^Lc5 and R ^Lc11 , R ^Lc6 and R ^Lc10 , R ^Lc8 and R ^Lc9 , or R ^Lc9 and R ^Lc10 may be bonded to each other to form a ring with the carbon atom to which they are bonded, and in this case, the group involved in the bond may contain a heteroatom having 1 to 15 carbon atoms. It is a hydrocarbylene group. In addition, R ^Lc2 and R ^Lc11 , R ^Lc8 and R ^Lc11 , or R ^Lc4 and R ^Lc6 are bonded to adjacent carbon atoms without any intermediary, forming a double bond. Good too. Note that this formula also represents a mirror image.

Here, examples of the monomer represented by formula (AL-3)-22 include those described in JP-A No. 2000-327633. Specifically, the following may be mentioned, but the invention is not limited thereto. In addition, in the following formula, R ^A is the same as above.

Monomers that provide repeating units containing an acid-labile group represented by formula (AL-3) include furandiyl, tetrahydrofurandiyl, or oxanorbornediyl groups represented by formula (AL-3)-23 below. Also mentioned are (meth)acrylic acid esters containing.

In formula (AL-3)-23, R ^A is the same as above. R ^Lc12 and R ^Lc13 are each independently a hydrocarbyl group having 1 to 10 carbon atoms. R ^Lc12 and R ^Lc13 may be bonded to each other to form an alicyclic ring together with the carbon atom to which they are bonded. R ^Lc14 is a furandiyl group, a tetrahydrofurandiyl group or an oxanorbornediyl group. R ^Lc15 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a hetero atom. The hydrocarbyl group may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups having 1 to 10 carbon atoms.

Examples of the monomer represented by formula (AL-3)-23 include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above, Ac is an acetyl group, and Me is a methyl group.

The base polymer further includes a hydroxy group, a carboxy group, a lactone ring, a carbonate bond, a thiocarbonate bond, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O- It may contain a repeating unit c containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-.

Examples of monomers providing the repeating unit c include those shown below, but are not limited thereto. In addition, in the following formula, R ^A is the same as above.

The base polymer further includes a repeating unit represented by the following formula (d1) (hereinafter also referred to as repeating unit d1) and a repeating unit represented by the following formula (d2) (hereinafter also referred to as repeating unit d2). and a repeating unit represented by the following formula (d3) (hereinafter also referred to as repeating unit d3).

In formulas (d1) to (d3), 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 is a carbonyl group, an ester bond, an ether bond, or a hydroxy group. May contain. 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 an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these; a carbonyl group, an ester bond, an ether bond, a bromine atom or an iodine atom; May contain. 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 is a carbonyl group, an ester bond, an ether bond, a halogen atom, or It may contain a hydroxy group. The aliphatic hydrocarbylene groups represented by Z ¹ , Z ¹¹ , Z ³¹ and Z ⁵¹ may be saturated or unsaturated, and may be linear, branched or cyclic.

In formulas (d1) to (d3), R ²¹ to R ²⁸ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a hetero atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified in the explanation of R ¹⁰¹ to R ¹⁰⁵ in formulas (1-1) and (1-2) below. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH ₂ - of the hydrocarbyl group A portion may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, or a nitro group. , carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-O-C(=O)-), haloalkyl group, etc. May contain. Furthermore, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may be bonded to each other to form a ring with the sulfur atom to which they are bonded. In this case, the ring is similar to the ring that is exemplified as a ring that can be formed by combining R ¹⁰¹ and R ¹⁰² together with the sulfur atom to which they are bonded in the explanation of formula (1-1) below. Can be mentioned.

In formula (d1), 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; Aryl sulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, 1,2,3,4,5-pentafluorobenzenesulfonate ion, alkylsulfonate ion such as mesylate ion, butanesulfonate ion, bis Imide ions such as (trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, bis(perfluorobutylsulfonyl)imide ion, methide ions such as tris(trifluoromethylsulfonyl)methide ion, tris(perfluoroethylsulfonyl)methide ion, etc. Can be mentioned.

The non-nucleophilic counter ion further includes a sulfonic acid ion in which the α-position represented by the following formula (d1-1) is substituted with a fluorine atom, and a sulfonic acid ion in which the α-position represented by the following formula (d1-2) is substituted with a fluorine atom. Examples include sulfonic acid ions substituted with a fluorine atom and a trifluoromethyl group substituted at the β position.

In formula (d1-1), 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. good. 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 ¹¹¹ in formula (1A') described below.

In formula (d1-2), R ³² is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyl carbonyl group having 2 to 30 carbon atoms, and the hydrocarbyl group and the hydrocarbyl carbonyl group have an ether bond or an ester bond. , a carbonyl group or a lactone ring. The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbyl carbonyl 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 ¹¹¹ in formula (1A') described below.

Examples of the cation of the monomer providing the repeating unit d1 include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above.

Specific examples of the cation of the monomer providing the repeating unit d2 or d3 include those similar to those exemplified as the cation of the sulfonium salt represented by formula (1-1) described below.

Examples of the anion of the monomer providing the repeating unit d2 include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above.

Examples of the anion of the monomer providing the repeating unit d3 include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above.

Repeating units d1 to d3 function as acid generators. By binding an acid generator to the polymer main chain, acid diffusion can be reduced and resolution can be prevented from deteriorating due to blurring of acid diffusion. Furthermore, LWR and CDU are improved by uniformly dispersing the acid generator. Note that when a base polymer containing repeating units d1 to d3 (ie, a polymer-bound acid generator) is used, the addition-type acid generator described later can be omitted.

The base polymer may include repeating units e other than the above-mentioned repeating units. Examples of the repeating unit e include those derived from styrene, vinylnaphthalene, acenaphthylene, indene, coumarin, coumaron, and the like.

In the base polymer, the content ratio of repeating units a, b1, b2, c, d1, d2, d3 and e is 0<a<1.0, 0≦b1≦0.9, 0≦b2≦0.9 , 0≦b1+b2≦0.9, 0≦c≦0.9, 0≦d1≦0.5, 0≦d2≦0.5, 0≦d3≦0.5, 0≦d1+d2+d3≦0.5 and 0 ≦e≦0.5 is preferable, 0.01≦a≦0.8, 0≦b1≦0.8, 0≦b2≦0.8, 0≦b1+b2≦0.8, 0≦c≦0.8 , 0≦d1≦0.4, 0≦d2≦0.4, 0≦d3≦0.4, 0≦d1+d2+d3≦0.4 and 0≦e≦0.4, and 0.02≦a≦ 0.7, 0≦b1≦0.7, 0≦b2≦0.7, 0≦b1+b2≦0.7, 0≦c≦0.7, 0≦d1≦0.3, 0≦d2≦0. 3, 0≦d3≦0.3, 0≦d1+d2+d3≦0.3 and 0≦e≦0.3 are more preferable. However, a+b1+b2+c+d1+d2+d3+e=1.0.

To synthesize the base polymer, for example, a monomer providing the above-described repeating unit may be polymerized by adding a radical polymerization initiator in an organic solvent and heating the mixture.

Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. As a polymerization initiator, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropiodine) nate), benzoyl peroxide, lauroyl peroxide, and the like. 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 a monomer containing a hydroxy group, the hydroxy group may be substituted with an acetal group that is easily deprotected with an acid such as an ethoxyethoxy group during polymerization, and deprotection may be performed with a weak acid and water after the polymerization. Alkaline hydrolysis may be performed after polymerization by substituting with an acetyl group, formyl group, pivaloyl group, etc.

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 described above to form hydroxystyrene or hydroxyvinylnaphthalene. It may also be naphthalene.

As the base for alkaline hydrolysis, aqueous ammonia, triethylamine, etc. can be used. Further, 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 polystyrene equivalent weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30, as measured by gel permeation chromatography (GPC) using THF as a solvent. ,000. If Mw is too small, the resist material will have poor heat resistance, and if it is too large, the alkali solubility will decrease, making it easy to cause trailing after pattern formation.

Furthermore, if the base polymer has a wide molecular weight distribution (Mw/Mn), the presence of low molecular weight or high molecular weight polymers may cause foreign matter to be seen on the pattern or the shape of the pattern to deteriorate after exposure. There is a risk of As pattern rules become finer, the influence of Mw and Mw/Mn tends to increase. Therefore, in order to obtain a resist material suitable for use in fine pattern dimensions, Mw/Mn of the base polymer should be 1.0. A narrow dispersion of ~2.0, particularly 1.0~1.5 is preferred.

The base polymer may include two or more polymers having different composition ratios, Mw, and Mw/Mn. Alternatively, a polymer containing repeating unit a and a polymer not containing repeating unit a but containing repeating units b1 and/or b2 may be blended.

[Acid generator]
The positive resist material of the present invention may further contain an acid generator that generates a strong acid (hereinafter also referred to as an additive acid generator). The term "strong acid" as used herein means a compound having sufficient acidity to cause a deprotection reaction of the acid-labile groups of the base polymer.

Examples of the acid generator include compounds that generate acid in response to actinic rays or radiation (photoacid generators). The photoacid generator is not particularly limited as long as it is a compound that generates acid when irradiated with high-energy rays, but those that generate sulfonic acid, imide acid, or methide acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloximide, oxime-O-sulfonate type acid generators, and the like. Specific examples of photoacid generators include those described in paragraphs [0122] to [0142] of JP-A No. 2008-111103.

Further, as a 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 formulas (1-1) and (1-2), R ¹⁰¹ to R ¹⁰⁵ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

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

Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH ₂ - of the hydrocarbyl group A portion may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, or a nitro group. , carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-O-C(=O)-), haloalkyl group, etc. May contain.

（式中、破線は、Ｒ¹⁰³との結合手である。） Further, 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. At this time, the ring preferably has the structure shown below.

(In the formula, the broken line is the bond with 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 formulas (1A) to (1D) below.

In formula (1A), R ^fa is a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain 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 ¹¹¹ in formula (1A') described below.

The anion represented by the formula (1A) is preferably one 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 hetero atom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. The hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms in order to obtain high resolution in fine pattern formation.

The hydrocarbyl group represented by R ¹¹¹ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2- Alkyl groups having 1 to 38 carbon atoms such as ethylhexyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group; cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantyl group Cyclic saturated hydrocarbyl group having 3 to 38 carbon atoms such as methyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group; allyl group , C2-38 unsaturated aliphatic hydrocarbyl groups such as 3-cyclohexenyl groups; C6-38 aryl groups such as phenyl, 1-naphthyl, 2-naphthyl groups; benzyl group, diphenylmethyl group Examples include aralkyl groups having 7 to 38 carbon atoms; groups obtained by combining these groups, and the like.

Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH ₂ - of the hydrocarbyl group A portion may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, or a nitro group. , carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-O-C(=O)-), haloalkyl group, etc. May contain. Hydrocarbyl groups containing heteroatoms include tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxymethyl group, 2-carboxylic -1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, 3-oxocyclohexyl group and the like.

Regarding the synthesis of a sulfonium salt containing an anion represented by formula (1A'), see JP-A No. 2007-145797, JP-A No. 2008-106045, JP-A No. 2009-7327, and JP-A No. 2009-258695. I am familiar with etc. Further, sulfonium salts described in JP-A No. 2010-215608, JP-A No. 2012-41320, JP-A No. 2012-106986, JP-A No. 2012-153644, etc. are also preferably used.

Examples of the anion represented by formula (1A) include those similar to those exemplified as the anion represented by formula (1A) in JP-A-2018-197853.

In formula (1B), R ^fb1 and R ^fb2 are each independently a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to 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. Furthermore, 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 -); in this case, R The group obtained by bonding ^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 fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to 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. Furthermore, R ^fc1 and R ^fc2 may be bonded to each other to form a ring together with the group to which they are bonded (-CF ₂ -SO ₂ -C ^- -SO ₂ -CF ₂ -); in this case, R The group obtained by bonding ^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 include those similar to those exemplified as the hydrocarbyl group represented by R ¹¹¹ in formula (1A').

Regarding the synthesis of a sulfonium salt containing an anion represented by formula (1D), see JP-A No. 2010-215608 and JP-A No. 2014-133723 for details.

Examples of the anion represented by formula (1D) include those similar to those exemplified as the anion represented by formula (1D) in JP-A-2018-197853.

Note that 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. As such, it has sufficient acidity to cleave acid-labile groups in the base polymer. Therefore, it can be used as a photoacid generator.

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

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

The hydrocarbyl group represented by R ²⁰¹ and R ²⁰² may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n- Alkyl groups having 1 to 30 carbon atoms such as hexyl group, n-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 group, norbornyl group, tricyclo[5.2.1.0 ^2,6 ]decanyl group, adamantyl group, etc. cyclic saturated hydrocarbyl group having 3 to 30 carbon atoms; phenyl group , methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group Aryl groups having 6 to 30 carbon atoms such as n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, anthracenyl group; combinations of these Examples include groups obtained by Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH ₂ - of the hydrocarbyl group A portion may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, or a nitro group. , carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-O-C(=O)-), haloalkyl group, etc. May contain.

The hydrocarbylene group represented by R ²⁰³ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include 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, -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- Alkanediyl groups having 1 to 30 carbon atoms such as diyl group and heptadecane-1,17-diyl group; cyclic saturated groups having 3 to 30 carbon atoms such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group Hydrocarbylene group; 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, tert-butylnaphthylene group, and other arylene groups having 6 to 30 carbon atoms. ; Examples include groups obtained by combining these. Further, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the - A part of CH ₂ - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, and as a result, a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano atom, etc. group, nitro group, carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-OC(=O)-), It may also contain a haloalkyl group or the like. The hetero atom is preferably an oxygen atom.

In formula (2), L ^C is a single bond, an ether bond, or a hydrocarbylene group having 1 to 20 carbon atoms and which may contain a hetero atom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to those exemplified as the hydrocarbylene group represented by ^R203 .

In formula (2), X ^A , X ^B , X ^C and X ^D are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group. However, at least one of X ^A , X ^B , X ^C and X ^D 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 formula (2') below.

In formula (2'), L ^C 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 hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to 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 the photoacid generator represented by formula (2) include those similar to those exemplified as the photoacid generator represented by formula (2) in JP-A No. 2017-026980.

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

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 also 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, and more preferably 2 or 3. r is preferably an integer satisfying 0≦r≦2.

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

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

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

In formulas (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 fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, or an amino group. a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, which may contain a group or an ether bond. , a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, or -N(R ^401A )(R ^401B ), -N(R ^401C )-C(=O)-R ^401D or -N(R ^401C )-C(=O)-OR ^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, 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 to 6 carbon atoms; It may contain up to 6 saturated hydrocarbylcarbonyloxy groups. R ^401D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms; group, 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 hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy 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.

Among these, R ⁴⁰¹ includes hydroxy group, -N(R ^401C )-C(=O)-R ^401D , -N(R ^401C )-C(=O)-O-R ^401D , fluorine atom, chlorine Atom, bromine atom, methyl group, methoxy group, etc. are preferable.

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. It is a fluoromethyl group. Furthermore, 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.

In formulas (3-1) and (3-2), R ⁴⁰² to R ⁴⁰⁶ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain 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 groups represented by R ¹⁰¹ to R ¹⁰⁵ in the explanation of formulas (1-1) and (1-2). Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone ring, a sulfo group, or a sulfonium salt-containing group. , a portion of --CH ₂ -- of the hydrocarbyl group may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond or sulfonic acid 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 those similar to those exemplified as the ring that can be formed by R ¹⁰¹ and R ¹⁰² bonding together with the sulfur atom to which they are bonded in the explanation of formula (1-1).

Examples of the cation of the sulfonium salt represented by formula (3-1) include those similar to those exemplified as the cation of the sulfonium salt represented by formula (1-1). Further, as the cation of the iodonium salt represented by the formula (3-2), the same cations as those exemplified as the cation of the iodonium salt represented by the formula (1-2) can be mentioned.

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 addition, in the following formula, X ^BI is the same as above.

When the positive resist material of the present invention contains an additive acid generator, its content is preferably 0.1 to 50 parts by weight, more preferably 1 to 40 parts by weight, based on 100 parts by weight of the base polymer. The additive acid generators may be used alone or in combination of two or more. Since the base polymer contains repeating units d1 to d3 and/or contains an additive acid generator, the positive resist material of the present invention can function as a chemically amplified positive resist material.

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

In the positive resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by weight, more preferably 200 to 8,000 parts by weight, based on 100 parts by weight of the base polymer. The organic solvents may be used alone or in combination of two or more.

[Quencher]
The positive resist material of the present invention may contain a quencher. Note that the quencher refers to a compound that can trap acid generated from an acid generator in the resist material and thereby prevent it from diffusing into unexposed areas.

The quencher includes 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 include nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and the like. In particular, primary, secondary, and tertiary amine compounds described in paragraphs [0146] to [0164] of JP-A No. 2008-111103, particularly hydroxy groups, ether bonds, ester bonds, lactone rings, An amine compound having a cyano group, a sulfonic acid ester bond, or a compound having a carbamate group described in Japanese Patent No. 3790649 is preferred. By adding such a basic compound, it is possible, for example, to further suppress the acid diffusion rate in the resist film or to correct the shape.

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

Such quenchers include, for example, the compound represented by the following formula (4) (an onium salt of a sulfonic acid whose α-position is not fluorinated) and the compound represented by the following formula (5) (an onium salt of a sulfonic acid whose α-position is not fluorinated). onium salts).

In formula (4), R ⁵⁰¹ is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a hetero atom, but the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is a fluorine atom. or excluding those substituted with a fluoroalkyl group.

The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n- Alkyl groups having 1 to 40 carbon atoms such as hexyl group, n-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 group, norbornyl group, tricyclo[5.2.1.0 ^2,6 ]decanyl group, adamantyl group, adamantylmethyl group, etc. cyclic saturated hydrocarbyl having 3 to 40 carbon atoms Group; Alkenyl group having 2 to 40 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; Cyclounsaturated aliphatic hydrocarbyl group having 3 to 40 carbon atoms such as cyclohexenyl group; Phenyl group, Naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), dialkyl group Phenyl groups (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl groups (methylnaphthyl group, ethylnaphthyl group, etc.), dialkylnaphthyl groups (dimethylnaphthyl group, diethylnaphthyl group, etc.) ); and aralkyl groups having 7 to 40 carbon atoms such as benzyl, 1-phenylethyl, and 2-phenylethyl.

Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH ₂ - of the hydrocarbyl group A portion 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, a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, It may contain a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl group and indolyl group; 4-hydroxyphenyl group, 4-methoxyphenyl group, 3-methoxyphenyl group, 2-methoxyphenyl group, 4-ethoxyphenyl group, Alkoxyphenyl groups such as 4-tert-butoxyphenyl group and 3-tert-butoxyphenyl group; Alkoxynaphthyl groups such as methoxynaphthyl group, ethoxynaphthyl group, n-propoxynaphthyl group, and n-butoxynaphthyl group; dimethoxynaphthyl group, Dialkoxynaphthyl groups such as diethoxynaphthyl groups; 2-aryl groups such as 2-phenyl-2-oxoethyl groups, 2-(1-naphthyl)-2-oxoethyl groups, and 2-(2-naphthyl)-2-oxoethyl groups; Examples include aryloxoalkyl groups such as -2-oxoethyl group.

In formula (5), R ⁵⁰² is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. Examples of the hydrocarbyl group represented by R ⁵⁰² include those similar to those exemplified as the hydrocarbyl group represented by R ⁵⁰¹ . Other specific examples include trifluoromethyl group, trifluoroethyl group, 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, 2,2,2-trifluoro-1-(trifluoro-1- Examples include fluorine-containing alkyl groups such as fluoromethyl)-1-hydroxyethyl group; fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group.

In formulas (4) and (5), Mq ⁺ is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Examples of the sulfonium cation include those exemplified as the cation of the sulfonium salt represented by formula (1-1). In addition, examples of the iodonium cation include those similar to those exemplified as the cation of the iodonium salt represented by formula (1-2).

As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (6) can also be suitably used.

In formula (6), R ⁶⁰¹ is 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 the hydrogen atom may be substituted with a halogen atom, A saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, or -N(R ^601A )-C(=O)-R ^601B or -N(R ^601A )-C(=O)-O-R ^601B . R ^601A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^601B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

In formula (6), x' is an integer from 1 to 5. y' is an integer from 0 to 3. z' is an integer from 1 to 3. L ¹¹ is a single bond or a (z'+1)-valent linking group having 1 to 20 carbon atoms, such as an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, or a hydroxyl group. It may contain at least one selected from a group and a carboxy group. 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' is 2 or more, each R ⁶⁰¹ may be the same or different.

In formula (6), R ⁶⁰² , R ⁶⁰³ and R ⁶⁰⁴ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain 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 groups represented by R ¹⁰¹ to R ¹⁰⁵ in formulas (1-1) and (1-2). Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group. , a portion of --CH ₂ -- of the hydrocarbyl group may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond or sulfonic acid ester bond. Further, R ⁶⁰² and R ⁶⁰³ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

Specific examples of the compound represented by formula (6) include those described in JP-A No. 2017-219836. Iodine atoms have a large absorption of EUV with a wavelength of 13.5 nm, so secondary electrons are generated during exposure, and the energy of the secondary electrons is transferred to the acid generator, promoting the decomposition of the quencher and increasing the sensitivity. can be improved.

Other examples of the quencher include polymer-type quenchers described in JP-A-2008-239918. This improves the rectangularity of the resist pattern by being oriented on the surface of the resist film. The polymer type quencher also has the effect of preventing pattern thinning and pattern top rounding when a protective film for immersion exposure is applied.

When the positive resist material of the present invention contains the quencher, its content is preferably 0 to 5 parts by weight, more preferably 0 to 4 parts by weight, based on 100 parts by weight of the base polymer. The quenchers may be used alone or in combination of two or more.

[Other ingredients]
The positive resist material of the present invention may contain a surfactant, a dissolution inhibitor, a water repellency improver, acetylene alcohol, etc. in addition to the above-mentioned components.

Examples of the surfactant include those described in paragraphs [0165] to [0166] of JP-A No. 2008-111103. By adding a surfactant, the coatability of the resist material can be further improved or controlled. When the positive resist material of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by weight based on 100 parts by weight of the base polymer. The surfactants may be used alone or in combination of two or more.

By incorporating a dissolution inhibitor into the positive resist material of the present invention, the difference in dissolution rate between exposed areas and unexposed areas can be further increased, and resolution can be further improved. The dissolution inhibitor is a compound having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, and which contains two or more phenolic hydroxy groups in the molecule. Compounds substituted with unstable groups in an overall proportion of 0 to 100 mol%, or compounds containing carboxy groups in the molecule, in which the hydrogen atoms of the carboxy groups are replaced by acid-labile groups in an average proportion of 50 to 100 mol% as a whole. Examples include compounds substituted with Specific examples include bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, and compounds in which the hydrogen atoms of the hydroxy group and carboxy group of cholic acid are replaced with acid-labile groups. , for example, described in paragraphs [0155] to [0178] of JP-A No. 2008-122932.

When the positive resist material of the present invention contains the dissolution inhibitor, its content is preferably 0 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the base polymer. The dissolution inhibitors may be used alone or in combination of two or more.

The water repellency improver improves the water repellency of the resist film surface, and can be used in immersion lithography without using a top coat. The water repellency improver is preferably a polymer containing a fluorinated alkyl group, a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue with a specific structure, etc. More preferred are those exemplified in JP-A No. 297590, JP-A No. 2008-111103, and the like. The water repellency improver needs to be dissolved in an alkaline developer or an organic solvent developer. The aforementioned specific water repellency improver having a 1,1,1,3,3,3-hexafluoro-2-propanol residue has good solubility in a 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 evaporation of the acid in PEB and preventing poor opening of the hole pattern after development. When the positive resist material of the present invention contains a water repellency improver, its content is preferably 0 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the base polymer. The water repellency improver may be used alone or in combination of two or more.

Examples of the acetylene alcohols include those described in paragraphs [0179] to [0182] of JP-A No. 2008-122932. When the positive resist material of the present invention contains acetylene alcohol, the content thereof is preferably 0 to 5 parts by weight based on 100 parts by weight of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[Pattern formation method]
When using the positive resist material of the present invention for manufacturing various integrated circuits, known lithography techniques can be applied. For example, a pattern forming method includes a step of forming a resist film on a substrate using the above-mentioned positive resist material, a step of exposing the resist film to high-energy radiation, and a step of exposing the exposed resist film to a developer. A method including a step of developing using.

First, the positive resist material of the present invention is applied to 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.) using 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. Apply to. This is 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 rays include ultraviolet rays, deep 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 using ultraviolet rays, deep ultraviolet rays, EUV, X-rays, soft The amount of irradiation is preferably about 1 to 200 mJ/cm ² , more preferably about 10 to 100 mJ/cm ² . When using EB as a high-energy beam, the exposure dose is preferably about 0.1 to 100 μC/cm ² , more preferably about 0.5 to 50 μC/cm ² , either directly or using a mask to form the desired pattern. Draw using The positive resist material of the present invention is particularly suitable for high-energy radiation 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, γ-rays, and synchrotron radiation. It is suitable for fine patterning using radiation, and particularly suitable for fine patterning using EB or EUV.

After exposure, PEB may be performed on a hot plate or in an oven, preferably at 50 to 150°C for 10 seconds to 30 minutes, more preferably at 60 to 120°C for 30 seconds to 20 minutes.

After exposure or PEB, preferably 0.1 to 10% by weight, more preferably 2 to 5% by weight of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH). , using an alkaline aqueous developer such as tetrabutylammonium hydroxide (TBAH) for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by dipping method, puddle method, or spray method. By developing the exposed resist film using a conventional method such as the above, the irradiated portions are dissolved in the developer, the unexposed portions are not dissolved, and a desired positive pattern is formed on the substrate.

Using the positive resist material, a negative pattern can also be obtained by organic solvent development. The developing solutions used at this time include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, and 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, 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 may be used alone or in combination of two or more.

At the end of development, rinse. The rinsing liquid is preferably a solvent that is mixed with the developer and does not dissolve the resist film. As such solvents, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms are preferably used.

Specifically, 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 , 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pene Tanol, 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 and the like.

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 Examples include ether, di-n-hexyl ether, and the like.

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. It will be done. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptyne, octyne, and the like.

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

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

It is also possible to shrink the hole pattern or trench pattern after development using thermal flow, RELACS technology or DSA technology. A shrink agent is applied onto the hole pattern, and crosslinking of the shrink agent occurs on the surface of the resist film due to the diffusion of an acid catalyst from the resist film during baking, and the shrink agent adheres to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds to remove excess shrink agent and reduce the hole pattern.

Hereinafter, the present invention will be specifically explained by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[1] Synthesis of monomer [Synthesis Example 1-1] Synthesis of monomer M-1 In a reaction vessel, 9.20 g of raw material compound C-1, 8.60 g of triethylamine, and 0.61 g of 4-dimethylaminopyridine were dissolved in 25 mL of acetonitrile. After dissolving, 7.32 g of methacrylic acid chloride was added dropwise to the reaction vessel while maintaining the temperature (internal temperature) at 40 to 60°C. After stirring for 19 hours at an internal temperature of 60° C., the reaction solution was cooled and 20 mL of saturated sodium bicarbonate solution was added to stop the reaction. Extract the target product with a mixed solvent of 25 mL of toluene, 15 mL of hexane, and 15 mL of ethyl acetate, perform normal aqueous work-up, distill off the solvent, and perform vacuum distillation to extract monomer M-1. 10.2 g of a colorless and transparent oil was obtained.

[Synthesis Examples 1-2 to 1-13] Synthesis of Monomers M-2 to M-13 The following monomers M-2 to M-13 were synthesized in the same manner as Synthesis Example 1-1 except that the raw material compounds were changed. Synthesized.

[2] Synthesis of polymer Monomers cM-1, cM-2, PM-1, PM-2, and AM-1 to AM-4 used in polymer synthesis are as follows. Further, the Mw of the polymer is a polystyrene equivalent value measured by GPC using THF as a solvent.

[Synthesis Example 2-1] Synthesis of Polymer P-1 To a 2 L flask were added 15.2 g of monomer M-1, 4.8 g of 4-hydroxystyrene, and 40 g of THF as a solvent. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-1. The composition of Polymer P-1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-2] Synthesis of Polymer P-2 To a 2L flask, add 6.6 g of monomer M-2, 5.1 g of monomer AM-1, 6.0 g of 3-hydroxystyrene, and 40 g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-2. The composition of Polymer P-2 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-3] Synthesis of Polymer P-3 To a 2 L flask were added 13.2 g of monomer M-3, 6.0 g of 3-hydroxystyrene, and 40 g of THF as a solvent. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-3. The composition of Polymer P-3 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-4] Synthesis of Polymer P-4 To a 2L flask, add 13.6 g of monomer M-4, 4.2 g of 3-hydroxystyrene, 11.9 g of monomer PM-1, and 40 g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-4. The composition of Polymer P-4 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-5] Synthesis of Polymer P-5 In a 2L flask, 2.8 g of monomer M-5, 5.2 g of 1-(cyclopropyl-1-yl)-1-methylethyl methacrylate, 3- 3.5 g of fluoro-4-(methylcyclohexyloxy)styrene, 4.8 g of 3-hydroxystyrene, 11.2 g of monomer PM-1, and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-5. The composition of Polymer P-5 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-6] Synthesis of Polymer P-6 In a 2L flask, add 3.6 g of monomer M-6, 6.4 g of 1-methyl-1-cyclopentyl methacrylate, 4.2 g of 4-hydroxystyrene, and the monomers. 11.0 g of PM-2 and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-6. The composition of Polymer P-6 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-7] Synthesis of Polymer P-7 In a 2L flask, add 4.6 g of monomer M-7, 8.7 g of monomer AM-2, 4.2 g of 3-hydroxystyrene, and 11 g of monomer PM-2. .0 g and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-7. The composition of Polymer P-7 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-8] Synthesis of Polymer P-8 In a 2L flask, add 3.7 g of monomer M-8, 8.7 g of monomer AM-2, 4.2 g of 3-hydroxystyrene, and 11 g of monomer PM-2. .0 g and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-8. The composition of Polymer P-8 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-9] Synthesis of Polymer P-9 To a 2L flask, add 13.9 g of monomer M-9, 4.2 g of 3-hydroxystyrene, 11.9 g of monomer PM-1, and 40 g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-9. The composition of Polymer P-9 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-10] Synthesis of Polymer P-10 To a 2L flask, add 11.6 g of monomer M-10, 4.2 g of 3-hydroxystyrene, 11.9 g of monomer PM-1, and 40 g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-10. The composition of Polymer P-10 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-11] Synthesis of Polymer P-11 In a 2L flask, 6.6g of monomer M-3, 4.5g of monomer AM-3, 5.4g of 3-hydroxystyrene, 0.5g of styrene, And 40g of THF was added as a solvent. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-11. The composition of Polymer P-11 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-12] Synthesis of Polymer P-12 In a 2L flask, add 6.6 g of monomer M-3, 4.5 g of monomer AM-4, 5.4 g of 3-hydroxystyrene, and 0.0 g of 4-methoxystyrene. .6 g and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-12. The composition of Polymer P-12 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-13] Synthesis of Polymer P-13 In a 2L flask, add 6.6g of monomer M-3, 4.5g of monomer AM-4, 3.0g of 3-hydroxystyrene, and 3.0g of 2-styrene. 0 g and 40 g of THF as a solvent were added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-13. The composition of Polymer P-13 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-14] Synthesis of Polymer P-14 In a 2L flask, 6.1g of monomer M-11, 4.5g of monomer AM-4, 6.0g of 3-hydroxystyrene, and 40g of THF as a solvent. Added. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-14. The composition of Polymer P-14 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-15] Synthesis of Polymer P-15 To a 2L flask, add 12.5g of monomer M-12, 4.2g of 3-hydroxystyrene, 11.9g of monomer PM-1, and 40g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-15. The composition of Polymer P-15 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Synthesis Example 2-16] Synthesis of Polymer P-16 To a 2L flask, add 12.5g of monomer M-13, 4.2g of 3-hydroxystyrene, 11.9g of monomer PM-1, and 40g of THF as a solvent. did. This reaction vessel was cooled to −70° C. under a nitrogen atmosphere, and vacuum degassing and nitrogen blowing were repeated three times. After the temperature was raised to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60°C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60°C to obtain Polymer P-16. The composition of Polymer P-16 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Comparative Synthesis Example 1] Synthesis of Comparative Polymer cP-1 Comparative polymer cP-1 was obtained in the same manner as Synthesis Example 2-1 except that monomer cM-1 was used instead of monomer M-1. The composition of comparative polymer cP-1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Comparative Synthesis Example 2] Synthesis of Comparative Polymer cP-2 Comparative polymer cP-2 was obtained in the same manner as Synthesis Example 2-1 except that monomer cM-2 was used instead of monomer M-1. The composition of comparative polymer cP-2 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[Comparative Synthesis Example 3] Synthesis of comparative polymer cP-3 Comparative polymer cP-3 was prepared in the same manner as in Synthesis Example 2-1, except that 1-methyl-1-cyclopentyl methacrylate was used instead of monomer M-1. I got it. The composition of comparative polymer cP-3 was confirmed by ¹³ C-NMR and ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC.

[3] Preparation of positive resist material and evaluation thereof [Examples 1 to 16, Comparative Examples 1 to 3]
(1) Preparation of positive resist material A solution prepared by dissolving each component with the composition shown in Table 1 in a solvent containing 50 ppm of PolyFox PF-636, a surfactant manufactured by Omnova, as a surfactant, was added to a 0.2 μm size solution. A positive resist material was prepared by filtration through a filter.

In Table 1, each component is as follows.
・Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)
DAA (Diacetone Alcohol)
EL (ethyl lactate)

・Acid generator: PAG-1, PAG-2

・Quencher: Q-1 to Q-3

(2) EUV lithography evaluation Each positive resist material shown in Table 1 was applied to 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. It was spin-coated onto a substrate and prebaked at 105° C. for 60 seconds using a hot plate to produce a resist film with a thickness of 60 nm. The resist film was exposed using an EUV scanner NXE3400 manufactured by ASML (NA 0.33, σ 0.9/0.6, quadruple pole illumination, 46 nm pitch on the wafer, +20% bias hole pattern mask), and was placed on a hot plate. PEB was performed for 60 seconds at the temperature listed in Table 1, and development was performed for 30 seconds with a 2.38% by mass TMAH aqueous solution to obtain a hole pattern with a size of 23 nm.
The exposure amount when each hole was formed with a size of 23 nm was measured, and this was defined as the sensitivity. In addition, the dimensions of 50 holes were measured using a length measurement SEM (CG6300) manufactured by Hitachi High-Technology Co., Ltd., and the three times the standard deviation (σ) calculated from the results (3σ) was determined as the CDU. The results are also listed in Table 1.

From the results shown in Table 1, the positive resist material of the present invention containing a base polymer containing a repeating unit represented by formula (a) had high sensitivity and good CDU.

Claims (11)

A positive resist material containing a base polymer containing a repeating unit represented by the following formula (a).

[Wherein, R ^A is a hydrogen atom or a methyl group.
X ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and a lactone ring.
R is a group represented by the following formula (a1).

(In the formula, R ¹ is a linear or branched aliphatic hydrocarbyl group having 1 to 6 carbon atoms that may contain an oxygen atom, and R ² is a linear or branched aliphatic hydrocarbyl group that may contain an oxygen atom. It is a shaped or branched unsaturated aliphatic hydrocarbyl group having 2 to 6 carbon atoms.Also, R ¹ and R ² are bonded to each other to form a ring having 5 to 12 carbon atoms together with the carbon atoms to which they are bonded. may be formed.
R ³ is a halogen atom, a cyano group, an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms substituted with a fluorine atom, or an alkyl group having 1 to 4 carbon atoms substituted with a fluorine atom; 4 is an alkylthio group.
R ⁴ is an alkyl group having 1 to 4 carbon atoms.
m is an integer from 1 to 5, and n is an integer from 0 to 4. However, 1≦m+n≦5.
The broken lines are bonds. )] The base polymer further comprises a repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group other than the group represented by formula (a1), and a repeating unit in which the hydrogen atom of the phenolic hydroxy group is substituted with an acid-labile group. 2. The positive resist material according to claim 1, comprising at least one repeating unit selected from repeating units. A repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group other than the group represented by formula (a1) is represented by the following formula (b1), and the hydrogen atom of the phenolic hydroxy group is 3. The positive resist material according to claim 2, wherein the repeating unit substituted with an acid-labile group is represented by the following formula (b2).

(In the formula, R ^A is each independently a hydrogen atom or a methyl group.
Y ¹ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, an ether bond, and 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 is an acid-labile group other than the group represented by formula (a1).
R ¹² is 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, and some of its -CH ₂ - groups may be substituted with an ether bond or an ester bond.
a is 1 or 2. b is an integer from 0 to 4. However, 1≦a+b≦5. ) The base polymer further includes a hydroxy group, a carboxy group, a lactone ring, a carbonate bond, a thiocarbonate bond, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O- The positive resist material according to any one of claims 1 to 3, which contains a repeating unit containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-. 5. The positive resist material according to claim 1, wherein the base polymer further contains a repeating unit represented by one of the following formulas (d1) to (d3).

(In the formula, 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 is a carbonyl group, an ester bond, an ether bond, or a hydroxy group. May contain.
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 an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these; a carbonyl group, an ester bond, an ether bond, an iodine atom or a bromine atom; May contain.
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 is a carbonyl group, an ester bond, an ether bond, a halogen atom, or It may contain a hydroxy group.
R ²¹ to R ²⁸ each independently represent a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a hetero atom. Furthermore, 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 counterion. ) The positive resist material according to claim 1, further comprising an acid generator. The positive resist material according to claim 1, further comprising an organic solvent. The positive resist material according to claim 1, further comprising a quencher. The positive resist material according to claim 1, further comprising a surfactant. A step of forming a resist film on a substrate using the positive resist material according to any one of claims 1 to 9, a step of exposing the resist film to high energy rays, and a step of exposing the exposed resist film to A pattern forming method comprising a step of developing using a developer. 11. The pattern forming method according to claim 10, wherein the high-energy beam is an i-line, a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or an extreme ultraviolet ray with a wavelength of 3 to 15 nm.