JP7420002B2 - Positive resist material and pattern forming method - Google Patents

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. In particular, logic devices used in smartphones and the like are driving the miniaturization, and 10 nm node logic devices are being mass-produced using a multiple exposure (multi-patterning lithography) process using ArF lithography.

The next 7nm node and 5nm node lithography are facing high costs due to multiple exposures and problems with overlay accuracy due to multiple exposures, and the arrival of extreme ultraviolet (EUV) lithography, which can reduce the number of exposures, is expected. has been done.

EUV, which has a wavelength of 13.5 nm, has a shorter wavelength of 1/10 or less than ArF lithography, which has a wavelength of 193 nm, so it is expected to have high contrast and high resolution. Since EUV has a short wavelength and high energy density, the acid generator becomes sensitive to a small amount of photons. The number of photons in EUV exposure is said to be 1/14 of that in ArF exposure. In EUV exposure, a phenomenon in which line edge roughness (LER, LWR) and hole dimensional uniformity (CDU) deteriorate due to photon variations has been viewed as a problem.

In order to reduce the variation in photons, it has been proposed to increase the number of photons absorbed within the resist film by increasing the light absorption of the resist material. For example, among halogen atoms, iodine atoms have high absorption in EUV at a wavelength of 13.5 nm, so in recent years, it has been proposed to use resins containing iodine atoms as EUV resist materials (Patent Documents 1 and 2). Iodine atoms have strong absorption and are expected to reduce edge roughness by absorbing many photons during EUV exposure, but their low alkali solubility reduces dissolution contrast, which increases edge roughness. .

In order to reduce edge roughness, molecular resist materials using low molecular weight compounds as a base have been studied. This is based on the idea that the smaller the molecular weight, the smaller the risk of increased edge roughness due to uneven dissolution of the resist film in the developer. However, chemically amplified molecular resist materials have a problem in that edge roughness deteriorates due to insufficient control of acid diffusion. Rather, the advantages of conventional polymer-type resist materials having smaller edge roughness and lower molecular weight of molecular resist materials remain unutilized. A highly absorbent calixarene-type molecular resist material containing iodine atoms has been proposed, but control of acid diffusion is a problem (Patent Document 3).

Japanese Patent Application Publication No. 2015-161823 JP 2018-4812 Publication International Publication No. 2013/024777

The present invention was made in view of the above circumstances, and provides a positive resist material that has higher sensitivity and resolution than conventional positive resist materials, has small edge roughness and CDU, and has a good pattern shape after exposure, and The purpose of the present invention is to provide a pattern forming method.

The inventor of the present invention has conducted intensive studies to obtain a positive resist material with high resolution and low edge roughness and dimensional variation, which has been demanded in recent years. In this case, there is a problem that the resolution of two-dimensional patterns such as hole patterns decreases due to a decrease in sensitivity and a decrease in dissolution contrast at the same time. A tertiary diester compound that has two ester bonds in its molecule increases the absorption of exposure light and increases the efficiency of acid generation, while minimizing the acid diffusion distance due to the presence of two acid-labile groups. It was discovered that after decomposition of acid-labile groups, the molecular size becomes smaller and the dissolution contrast is improved, and that it is extremely effective when used as a base for chemically amplified positive resist materials. did.

Since the ester compound of 2-phenyl-2-propanol undergoes a very fast deprotection reaction with an acid, it is difficult to control the acid diffusion and deprotection reaction rates. In order to solve this problem, it has been proposed to introduce a fluorine atom into the phenyl group, as described in, for example, JP-A-2013-80031. The presence of the electron-withdrawing fluorine atom prevents the stability of the carbocation, which is an intermediate in the deprotection reaction, from becoming too high, and makes it possible to maintain an appropriate deprotection reaction rate and acid diffusion distance. The higher the stability of the carbocation, the easier the deprotection reaction will proceed, and the longer the acid diffusion distance will be. The tertiary diester compound has appropriate carbocation stability due to the electron-withdrawing effect due to two ester bonds. However, when one tertiary ester bond is broken, there is no electron-withdrawing group, so the deprotection reaction of the other tertiary ester bond proceeds very quickly. In other words, when one of them is deprotected, the other deprotection reaction rapidly progresses, resulting in a high solubility contrast. Furthermore, since the acid diffusion distance is dominated by the progress of the initial deprotection reaction, maximum contrast can be obtained with minimum acid diffusion.

Furthermore, in order to improve the dissolution contrast, by using a base polymer containing a repeating unit in which the hydrogen atom of a carboxy group or phenolic hydroxyl group is replaced with an acid-labile group, high sensitivity and alkali dissolution before and after exposure can be achieved. A positive resist material is obtained that has significantly high speed contrast, high resolution, and good pattern shape, edge roughness, and CDU after exposure, and is particularly suitable for VLSI manufacturing or as a material for forming fine patterns in photomasks. The present invention was completed based on the knowledge that

（式中、Ｒ^1A及びＲ^1Bは、それぞれ独立に、ヒドロキシ基、炭素数１～６の飽和ヒドロカルビル基、炭素数１～６の飽和ヒドロカルビルオキシ基、炭素数２～６の飽和ヒドロカルビルカルボニルオキシ基、炭素数１～４の飽和ヒドロカルビルスルホニルオキシ基、フッ素原子、塩素原子、臭素原子、アミノ基、ニトロ基、シアノ基、－Ｎ(Ｒ^1C)－Ｃ(＝Ｏ)－Ｒ^1D又は－Ｎ(Ｒ^1C)－Ｃ(＝Ｏ)－Ｏ－Ｒ^1Dである。Ｒ^1Cは、水素原子又は炭素数１～６の飽和ヒドロカルビル基である。Ｒ^1Dは、炭素数１～８の脂肪族ヒドロカルビル基である。また、前記飽和ヒドロカルビル基、飽和ヒドロカルビルオキシ基、飽和ヒドロカルビルカルボニルオキシ基、飽和ヒドロカルビルスルホニルオキシ基及び脂肪族ヒドロカルビル基は、その水素原子の一部又は全部がハロゲン原子で置換されていてもよく、その炭素－炭素原子間にエーテル結合又はエステル結合が介在していてもよい。
Ｒ^2A及びＲ^2Bは、それぞれ独立に、単結合又は炭素数１～６の飽和ヒドロカルビレン基である。
Ｒ³～Ｒ⁶は、それぞれ独立に、炭素数１～８の飽和ヒドロカルビル基であり、Ｒ³とＲ⁴とが、互いに結合してこれらが結合する炭素原子とともに環を形成していてもよく、Ｒ⁵とＲ⁶とが、互いに結合してこれらが結合する炭素原子とともに環を形成していてもよい。
Ｒ⁷は、炭素数２～１０の脂肪族ヒドロカルビレン基又はフェニレン基である。
ｍ、ｎ、ｐ及びｑは、０≦ｍ≦５、０≦ｎ≦５、０≦ｐ≦５、０≦ｑ≦５、０≦ｍ＋ｐ≦５、０≦ｎ＋ｑ≦５及び１≦ｍ＋ｎ≦１０を満たす整数である。）
３．更に、ベースポリマーを含む１又は２のポジ型レジスト材料。
４．前記ベースポリマーが、カルボキシ基の水素原子が酸不安定基で置換されている繰り返し単位及び／又は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ている繰り返し単位を含む３のポジ型レジスト材料。
５．前記カルボキシ基の水素原子が酸不安定基で置換されている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ている繰り返し単位が、それぞれ下記式（ａ１）で表される繰り返し単位及び下記式（ａ２）で表される繰り返し単位である４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。
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、エーテル結合若しくはラクトン環を含む炭素数１～１２の連結基である。
Ｘ²は、単結合、エステル結合又はアミド結合である。
Ｘ³は、単結合、エーテル結合又はエステル結合である。
Ｒ¹¹及びＲ¹²は、酸不安定基である。
Ｒ¹³は、フッ素原子、トリフルオロメチル基、シアノ基又は炭素数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の飽和ヒドロカルビレン基であり、その炭素原子の一部がエーテル結合又はエステル結合で置換されていてもよい。
ａは、１又は２である。ｂは、０～４の整数である。ただし、１≦ａ＋ｂ≦５である。）
６．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、カーボネート基、チオカーボネート基、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ｂを含むものである３～５のいずれかのポジ型レジスト材料。
７．前記ベースポリマーが、更に、下記式（ｃ１）～（ｃ３）のいずれかで表される繰り返し単位を含むものである３～６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。
Ｙ¹は、単結合、フェニレン基、ナフチレン基、－Ｏ－Ｙ¹¹－、－Ｃ(＝Ｏ)－Ｏ－Ｙ¹¹－又は－Ｃ(＝Ｏ)－ＮＨ－Ｙ¹¹－である。Ｙ¹¹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。
Ｙ²は、単結合又はエステル結合である。
Ｙ³は、単結合、－Ｙ³¹－Ｃ(＝Ｏ)－Ｏ－、－Ｙ³¹－Ｏ－又は－Ｙ³¹－Ｏ－Ｃ(＝Ｏ)－である。Ｙ³¹は、炭素数１～１２のヒドロカルビレン基、フェニレン基又はこれらを組み合わせて得られる炭素数７～１８の基であり、カルボニル基、エステル結合、エーテル結合、ヨウ素原子又は臭素原子を含んでいてもよい。
Ｙ⁴は、単結合、メチレン基又は２,２,２－トリフルオロ－１,１－エタンジイル基である。
Ｙ⁵は、単結合、メチレン基、エチレン基、フェニレン基、フッ素化フェニレン基、－Ｏ－Ｙ⁵¹－、－Ｃ(＝Ｏ)－Ｏ－Ｙ⁵¹－又は－Ｃ(＝Ｏ)－ＮＨ－Ｙ⁵¹－である。Ｙ⁵¹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。
Ｒｆ¹及びＲｆ²は、それぞれ独立に、水素原子、フッ素原子又はトリフルオロメチル基であるが、少なくとも１つはフッ素原子である。
Ｒ²¹～Ｒ²⁸は、それぞれ独立に、フッ素原子、塩素原子、臭素原子、ヨウ素原子、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いてもよい。
Ｍ^-は、非求核性対向イオンである。）
８．更に、酸発生剤を含む１～７のいずれかのポジ型レジスト材料。
９．更に、有機溶剤を含む１～８のいずれかのポジ型レジスト材料。
１０．更に、クエンチャーを含む１～９のいずれかのポジ型レジスト材料。
１１．更に、界面活性剤を含む１～１０のいずれかのポジ型レジスト材料。
１２．１～１１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。
１３．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１２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 tertiary diester compound having two ester bonds bonded to a group containing an aromatic ring substituted with an iodine atom and a tertiary carbon atom in the molecule.
2. 1. The positive resist material of 1, wherein the tertiary diester compound is represented by the following formula (1).

(In the formula, R ^1A and R ^1B are each independently a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. , a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, -N(R ^1C )-C(=O)-R ^1D or -N( R ^1C )-C(=O)-O-R ^1D . R ^1C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^1D is an aliphatic hydrocarbyl group having 1 to 8 carbon atoms. In addition, the saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyl carbonyloxy group, saturated hydrocarbylsulfonyloxy group, and aliphatic hydrocarbyl group may have some or all of their hydrogen atoms substituted with halogen atoms. Often, an ether bond or ester bond may be present between the carbon atoms.
R ^2A and R ^2B are each independently a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms.
R ³ to R ⁶ are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms, and R ³ and R ⁴ may be bonded to each other to form a ring with the carbon atom to which they are bonded. , R ⁵ and R ⁶ may be bonded to each other to form a ring together with the carbon atom to which they are bonded.
R ⁷ is an aliphatic hydrocarbylene group having 2 to 10 carbon atoms or a phenylene group.
m, n, p and q are 0≦m≦5, 0≦n≦5, 0≦p≦5, 0≦q≦5, 0≦m+p≦5, 0≦n+q≦5 and 1≦m+n≦10 It is an integer that satisfies the following. )
3. Additionally, one or two positive resist materials comprising a base polymer.
4. 3. Positive type, wherein the base polymer contains a repeating unit in which the hydrogen atom of a carboxy group is substituted with an acid-labile group and/or a repeating unit in which the hydrogen atom of a phenolic hydroxy group is substituted with an acid-labile group. resist material.
5. The repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group and the repeating unit in which the hydrogen atom of the phenolic hydroxy group is substituted with an acid-labile group are each represented by the following formula (a1). A positive resist material of 4, which is a repeating unit and a repeating unit represented by the following formula (a2).

(In the formula, R ^A is each independently 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 containing an ester bond, ether bond, or lactone ring.
X ² is a single bond, an ester bond or an amide bond.
X ³ is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are acid labile groups.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms.
R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and some of its carbon atoms 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. )
6. The base polymer further includes a hydroxy group, a carboxy group, a lactone ring, a carbonate group, a thiocarbonate group, 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 3 to 5, which contains a repeating unit b containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-.
7. 7. The positive resist material according to any one of 3 to 6, wherein the base polymer further contains a repeating unit represented by any of the following formulas (c1) to (c3).

(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, -O-Y ¹¹ -, -C(=O)-O-Y ¹¹ - or -C(=O)-NH-Y ¹¹ -. Y 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.
Y ² is a single bond or an ester bond.
Y ³ is a single bond, -Y ³¹ -C(=O)-O-, -Y ³¹ -O-, or -Y ³¹ -O-C(=O)-. Y ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and does not contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. It's okay to stay.
Y ⁴ is a single bond, a methylene group or a 2,2,2-trifluoro-1,1-ethanediyl group.
Y ⁵ is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, -O-Y ⁵¹ -, -C(=O)-O-Y ⁵¹ - or -C(=O)-NH- Y ⁵¹ -. Y ⁵¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and contains a carbonyl group, an ester bond, an ether bond, or a hydroxy group. You can stay there.
Rf ¹ and Rf ² are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one is a fluorine atom.
R ²¹ to R ²⁸ are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. Further, 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. )
8. The positive resist material according to any one of 1 to 7, further comprising an acid generator.
9. Further, any one of positive resist materials 1 to 8 containing an organic solvent.
10. Further, the positive resist material according to any one of 1 to 9, containing a quencher.
11. The positive resist material according to any one of 1 to 10, further comprising a surfactant.
12. A step of forming a resist film on a substrate using the positive resist material according to any one of 1 to 11, 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:
13. 12. The pattern forming method according to 12, 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, and high resolution, and has improved pattern shape, edge roughness, and CDU is good. 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 is characterized by containing a tertiary diester compound having two ester bonds in the molecule to which a group containing an aromatic ring substituted with an iodine atom and a tertiary carbon atom are bonded. shall be.

[Tertiary diester compound]
The tertiary diester compound is preferably one represented by the following formula (1).

In formula (1), R ^1A and R ^1B each independently represent a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, or a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms. Oxy group, saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, fluorine atom, chlorine atom, bromine atom, amino group, nitro group, cyano group, -N(R ^1C )-C(=O)-R ^1D or - N(R ^1C )-C(=O)-O-R ^1D , R ^1C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R ^1D is an aliphatic group having 1 to 8 carbon atoms. It is a hydrocarbyl group.

The saturated hydrocarbyl group having 1 to 6 carbon atoms represented by R ^1A , R ^1B and R ^1C may be linear, branched, or cyclic, and specific examples thereof include methyl group, ethyl group, and propyl group. , an alkyl group such as isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group; cyclic saturated hydrocarbyl group such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group; Examples include groups obtained in combination. The saturated hydrocarbyl moieties of the saturated hydrocarbyloxy group, saturated hydrocarbyl carbonyloxy group and saturated hydrocarbylsulfonyloxy group include those having 1 to 6 carbon atoms and those having 1 to 5 carbon atoms, respectively, from among the specific examples of the saturated hydrocarbyl group described above. and those having 1 to 4 carbon atoms.

The aliphatic hydrocarbyl group represented by R ^1D may be linear, branched, or cyclic, and may be saturated or unsaturated. Specific examples thereof include those exemplified as saturated hydrocarbyl groups represented by R ^1A and R ^1B , alkenyl groups such as vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, hexenyl group; cyclohexenyl group cycloalkenyl groups such as cycloalkenyl groups; groups obtained by combining these groups, and the like.

Further, in the saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbylsulfonyloxy group, and aliphatic hydrocarbyl group, some or all of the hydrogen atoms thereof may be substituted with a halogen atom, An ether bond or ester bond may exist between carbon and carbon atoms.

R ^1A and R ^1B include a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may have an ether bond between carbon atoms, an amino group, -N(R ^1C )-C(= O)-R ^1D or -N(R ^1C )-C(=O)-O-R ^1D is preferred.

In formula (1), R ^2A and R ^2B are each independently a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, and propane-1,2-diyl group. 1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, 1-methylethane-1,2-diyl group, butane-1,1 -diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, 1,1-dimethylethane-1,2 Alkanediyl groups such as -diyl group, pentane-1,5-diyl group, 2-methylbutane-1,2-diyl group, hexane-1,6-diyl group; cyclopropane-1,1-diyl group, cyclopropane -1,2-diyl group, cyclobutane-1,1-diyl group, cyclobutane-1,2-diyl group, cyclobutane-1,3-diyl group, cyclopentane-1,1-diyl group, cyclopentane-1, 2-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,1-diyl group, cyclohexane-1,2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group and other cycloalkanediyl groups; and groups obtained by combining these groups. R ^2A and R ^2B are preferably a single bond or a saturated hydrocarbylene group having 1 to 4 carbon atoms.

In formula (1), R ³ to R ⁶ are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms. Further, R ³ and R ⁴ may be bonded to each other to form a ring together with the carbon atom to which they are bonded, and R ⁵ and R ⁶ may be bonded to each other to form a ring together with the carbon atom to which they are bonded. may be formed. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include the same ones as exemplified as the saturated hydrocarbyl groups represented by R ^1A and R ^1B . R ³ to R ⁶ are preferably saturated hydrocarbyl groups having 1 to 3 carbon atoms.

In formula (1), R ⁷ is an aliphatic hydrocarbylene group having 2 to 10 carbon atoms or a phenylene group. The aliphatic hydrocarbylene group may be linear, branched, or cyclic, and may be saturated or unsaturated. Specific examples include ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group. , propane-2,2-diyl group, 1-methylethane-1,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane- 2,3-diyl group, butane-1,4-diyl group, 1,1-dimethylethane-1,2-diyl group, pentane-1,5-diyl group, 2-methylbutane-1,2-diyl group, Alkanediyl groups such as hexane-1,6-diyl group, heptanediyl group, octanediyl group, nonanediyl group, decanediyl group; cyclopropane-1,1-diyl group, cyclopropane-1,2-diyl group, cyclobutane- 1,1-diyl group, cyclobutane-1,2-diyl group, cyclobutane-1,3-diyl group, cyclopentane-1,1-diyl group, cyclopentane-1,2-diyl group, cyclopentane-1, Cycloalkanediyl groups such as 3-diyl group, cyclohexane-1,1-diyl group, cyclohexane-1,2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group; vinylene group, Alkenediyl groups such as 1-propene-1,3-diyl group, 1-butene-1,4-diyl group, 2-butene-1,4-diyl group; cycloalkenediyl group such as cyclohexenediyl group; ethynylene group , 1-propyne-1,3-diyl group, 1-butyne-1,4-diyl group, 2-butyne-1,4-diyl group; cycloalkynediyl group such as cyclohexynediyl group; and a group obtained by combining these and a methanediyl group. R ⁷ is preferably an alkanediyl group having 2 to 6 carbon atoms, a cycloalkanediyl group having 3 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, an alkynediyl group having 2 to 6 carbon atoms, or a phenylene group; More preferably, an alkanediyl group having 2 to 4 carbon atoms, a cycloalkanediyl group having 3 to 6 carbon atoms, an alkenediyl group having 2 to 4 carbon atoms, an alkynediyl group having 2 to 4 carbon atoms, or a phenylene group having 2 to 4 carbon atoms. More preferred are an alkynediyl group or a phenylene group.

In formula (1), m, n, p and q are 0≦m≦5, 0≦n≦5, 0≦p≦5, 0≦q≦5, 0≦m+p≦5, 0≦n+q≦5 and 1≦m+n≦10. In particular, m and n are preferably integers satisfying 1≦m≦3, 0≦n≦3, and 1≦m+n≦6.

Examples of the tertiary diester compound include, but are not limited to, those shown below.

The tertiary diester compound has two ester bonds in its molecule to which a group containing an aromatic ring substituted with an iodine atom and a tertiary carbon atom are bonded. It decomposes to generate carboxylic acid, which becomes a positive resist material that dissolves in an alkaline developer. Therefore, it is necessary to separately add an acid generator. Since the two ester bonds are located close to each other, the tertiary diester compound is a molecular resist material capable of generating carboxylic acid with minimal acid diffusion. When the tertiary diester compound has a nitrogen atom in the molecule, the ability to control acid diffusion is further improved. Since the tertiary diester compound has an iodine atom that absorbs a large amount of light, secondary electrons are generated during exposure, which promotes decomposition of the acid generator, thereby increasing the sensitivity. This makes it possible to simultaneously achieve high sensitivity, high resolution, low LWR, and low CDU.

The tertiary diester compound can be synthesized, for example, by an esterification reaction between a carboxylic acid having a group containing an aromatic ring substituted with an iodine atom and a diol compound having two tertiary hydroxy groups.

[Base polymer]
The positive resist material of the present invention may be a molecular resist material based on the tertiary diester compound, or may further contain a base polymer.

In order to improve the dissolution contrast, the base polymer is a repeating unit in which the hydrogen atom of a carboxy group is substituted with an acid-labile group (hereinafter also referred to as repeating unit a1) and/or a repeating unit in which the hydrogen atom of a phenolic hydroxy group is substituted with an acid-labile group. It is preferable to include a repeating unit substituted with an unstable group (hereinafter also referred to as repeating unit a2).

Examples of the repeating units a1 and a2 include those represented by the following formulas (a1) and (a2), respectively.

In formulas (a1) and (a2), R ^A is each independently 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 containing an ester bond, ether bond, or lactone ring. X ² is a single bond, an ester bond or an amide bond. X ³ is a single bond, an ether bond or an ester bond. R ¹¹ and R ¹² are acid labile groups. R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and some of its carbon atoms 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 a1 include those shown below, but are not limited thereto. In addition, in the following formula, R ^A and R ¹¹ are the same as above.

Examples of monomers that provide the repeating unit a2 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 dashed line is the bond.)

In formula (AL-1), R ^L1 is a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, and a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms. , a carbonyl group, a saturated hydrocarbyl group having 4 to 20 carbon atoms containing an ether bond or an ester bond, or a group represented by formula (AL-3). A1 is an integer from 0 to 6. 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 trialkylsilyl 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 dashed line is the bond.)

In formulas (AL-1)-1 to (AL-1)-10, A1 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, propyl group, isopropyl group, n-butyl group, sec-butyl group, and tert-butyl group. group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, n-octyl group, etc.

（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 dashed line is the 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 dashed line is the 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 each independently represents a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group may be linear, branched, or cyclic. B1 and D1 are each independently an integer of 0 to 10, preferably an integer of 0 to 5, and C1 is an integer of 1 to 7, preferably an integer of 1 to 3.

In formula (AL-2a) or (AL-2b), L ^A is a (C1+1)-valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, or a (C1+1)-valent alicyclic group having 3 to 50 carbon atoms. A saturated hydrocarbon group, a (C1+1) valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or a (C1+1) valent heterocyclic group having 3 to 50 carbon atoms. In addition, some of the carbon atoms of these groups may be substituted with a hetero atom-containing group, and some of the hydrogen atoms bonded to the carbon atoms of these groups may be substituted with a hydroxy group, a carboxy group, an acyl group, or a fluorine group. May be substituted with an atom. 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 dashed line is the 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, 11-diethylpropyl group, 1-ethylnorbornyl group, 1-methylcyclohexyl group, 1-ethylcyclopentyl group, 2-(2-methyl ) adamantyl group, 2-(2-ethyl)adamantyl group, tert-pentyl group, etc.

（式中、破線は結合手である。） Furthermore, examples of the group represented by formula (AL-3) include groups represented by formulas (AL-3)-1 to (AL-3)-18 below.

(In the formula, the dashed line is the bond.)

In formulas (AL-3)-1 to (AL-3)-18, 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.

（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)-19 or (AL-3)-20. The polymer may be intramolecularly or intermolecularly crosslinked by the acid-labile groups.

(In the formula, the dashed line is the bond.)

In formulas (AL-3)-19 and (AL-3)-20, R ^L14 is the same as above. R ^L18 is an (E1+1) valent saturated hydrocarbylene group having 1 to 20 carbon atoms or an (E1+1) valent arylene group having 6 to 20 carbon atoms; May contain. The saturated hydrocarbylene group may be linear, branched, or cyclic. E1 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)-21 below. It will be done.

In formula (AL-3)-21, 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 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; in this case, the group involved in the bond is a hydrocarbyl group that may contain a heteroatom having 1 to 15 carbon atoms. It is a ren group. Furthermore, R ^Lc2 and R ^Lc11 , R ^Lc8 and R ^Lc11 , or R ^Lc4 and R ^Lc6 may bond to adjacent carbons without any intervening bond to form a double bond. good. Note that this formula also represents a mirror image.

Here, monomers that provide the repeating unit represented by formula (AL-3)-21 include those described in JP-A-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 a repeating unit containing an acid-labile group represented by formula (AL-3) include a furandiyl group, a tetrahydrofurandiyl group, or an oxanorbornediyl group represented by the following formula (AL-3)-22. Also mentioned are (meth)acrylic acid esters containing.

In formula (AL-3)-22, 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.

Monomers that provide the repeating unit represented by formula (AL-3)-22 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 group, a thiocarbonate group, 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 b containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-.

Examples of monomers providing the repeating unit b 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 may further include a repeating unit c derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units c include a repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c1) and a repeating unit represented by the following formula (c2) (hereinafter also referred to as repeating unit c2). and a repeating unit represented by the following formula (c3) (hereinafter also referred to as repeating unit c3). Note that the repeating units c1 to c3 can be used singly or in combination of two or more.

In formulas (c1) to (c3), R ^A is each independently a hydrogen atom or a methyl group. Y ¹ is a single bond, a phenylene group, a naphthylene group, -O-Y ¹¹ -, -C(=O)-O-Y ¹¹ - or -C(=O)-NH-Y ¹¹ -. Y 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. Y ² is a single bond or an ester bond. Y ³ is a single bond, -Y ³¹ -C(=O)-O-, -Y ³¹ -O-, or -Y ³¹ -O-C(=O)-. Y ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and does not contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. It's okay to stay. Y ⁴ is a single bond, a methylene group or a 2,2,2-trifluoro-1,1-ethanediyl group. Y ⁵ is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, -O-Y ⁵¹ -, -C(=O)-O-Y ⁵¹ - or -C(=O)-NH- Y ⁵¹ -. Y ⁵¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and contains a carbonyl group, an ester bond, an ether bond, or a hydroxy group. You can stay there.

In formula (c2), Rf ¹ and Rf ² are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one is a fluorine atom. In particular, it is preferable that both Rf ¹ and Rf ² are fluorine atoms.

In formulas (c1) to (c3), R ²¹ to R ²⁸ are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. It is. The hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof are exemplified in the explanation of R ¹⁰¹ to R ¹⁰⁵ in formulas (2-1) and (2-2) below. Similar items can be mentioned.

Further, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring include those similar to those described later as a 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 (2-1). .

In formula (c1), 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 (c1-1) is substituted with a fluorine atom, and a sulfonic acid ion in which the α-position represented by the following formula (c1-2) 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 (c1-1), R ³¹ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be linear, branched, or cyclic. Specific examples include those similar to those described below as the hydrocarbyl group represented by R ¹⁰⁷ in formula (2A').

In formula (c1-2), 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 contains an ether bond, an ester bond, a carbonyl group, or a lactone ring. You can stay there. 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 of the hydrocarbyl group include those similar to those described below as the hydrocarbyl group represented by R ¹⁰⁷ in formula (2A').

Examples of the cation of the monomer providing the repeating unit c1 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 c2 or c3 include those similar to those described below as the cation of the sulfonium salt represented by formula (2-1).

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 c3 include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above.

The repeating units c1 to c3 have the function of an acid generator. 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 is improved by uniformly dispersing the acid generator. Note that when a base polymer containing the repeating unit d is used, the addition type acid generator described later may be omitted.

The base polymer may further include a repeating unit d that does not contain an amino group but contains an iodine atom. Monomers that provide the repeating unit d include, but are not limited to, those shown below. In addition, in the following formula, R ^A is the same as above.

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, acenaphthylene, indene, coumarin, coumaron, and the like.

In the base polymer, the content ratio of repeating units a1, a2, b, c1, c2, c3, d and e is 0≦a1≦0.9, 0≦a2≦0.9, 0<a1+a2≦0.9 , 0≦b≦0.9, 0≦c1≦0.5, 0≦c2≦0.5, 0≦c3≦0.5, 0≦c1+c2+c3≦0.5, 0≦d≦0.5 and 0 ≦e≦0.5 is preferable, 0≦a1≦0.8, 0≦a2≦0.8, 0<a1+a2≦0.8, 0≦b≦0.8, 0≦c1≦0.4, 0 More preferably ≦c2≦0.4, 0≦c3≦0.4, 0≦c1+c2+c3≦0.4, 0≦d≦0.4 and 0≦e≦0.4, 0≦a1≦0.7, 0≦a2≦0.7, 0≦a1+a2≦0.7, 0≦b≦0.7, 0≦c1≦0.3, 0≦c2≦0.3, 0≦c3≦0.3, 0≦ More preferably c1+c2+c3≦0.3, 0≦d≦0.3 and 0≦e≦0.3. However, a1+a2+b+c1+c2+c3+d+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 has a polystyrene equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) using THF as a solvent, preferably 1,000 to 500,000, more preferably 2,000 to 30,000. It is. 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.

When the positive resist material of the present invention contains a base polymer, the content thereof is preferably 10 to 1,000 parts by mass, more preferably 20 to 500 parts by mass, based on 100 parts by mass of the tertiary diester compound. More preferably 50 to 200 parts by mass. The base polymer may include two or more polymers having different composition ratios, Mw, and Mw/Mn.

[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 may be any compound as long as it generates an acid upon irradiation 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 (2-1) or an iodonium salt represented by the following formula (2-2) can also be suitably used.

In formulas (2-1) and (2-2), R ¹⁰¹ to R ¹⁰⁵ each independently have a carbon number of 1 to 1 and may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hetero atom. 20 hydrocarbyl groups.

The hydrocarbyl group 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; Cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms; vinyl group, propenyl group, butenyl group alkenyl groups having 2 to 20 carbon atoms such as cyclohexenyl and hexenyl groups; cyclounsaturated aliphatic hydrocarbyl groups having 2 to 20 carbon atoms such as cyclohexenyl and norbornenyl groups; ethynyl groups, propynyl groups, butynyl groups, etc. Alkynyl group having 2 to 20 carbon atoms; phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group groups, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, etc. with 6 or more carbon atoms 20 aryl groups; aralkyl groups having 7 to 20 carbon atoms such as benzyl groups and phenethyl groups; and the like. In addition, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc., and some of the carbon atoms of these groups are substituted with oxygen atoms. atoms, sulfur atoms, nitrogen atoms, etc., and as a result, hydroxy groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate groups, lactone rings, It may contain a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like.

（式中、破線は、Ｒ¹⁰³との結合手である。） Furthermore, R ¹⁰¹ and R ¹⁰² may be bonded together 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 (2-1) include, but are not limited to, those shown below.

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

In formulas (2-1) and (2-2), X ^- is an anion selected from formulas (2A) to (2D) below.

In formula (2A), R ^fa is a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms and which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic, and specific examples thereof include those mentioned below in the description of R ¹⁰⁷ .

The anion represented by the formula (2A) is preferably one represented by the following formula (2A').

In formula (2A'), R ¹⁰⁶ is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ¹⁰⁷ 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 ¹⁰⁷ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group. , nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group; alkyl group such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbor Cyclic saturated hydrocarbyl groups such as nylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group; unsaturated hydrocarbyl groups such as allyl group and 3-cyclohexenyl group; phenyl and aryl groups such as 1-naphthyl group and 2-naphthyl group; and aralkyl groups such as benzyl group and diphenylmethyl group.

In addition, some or all of the hydrogen atoms of these groups may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the carbon atoms of these groups It may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, or a lactone ring. , a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. 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 (2A'), 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 (2A) include those similar to those exemplified as the anion represented by formula (1A) in JP-A-2018-197853.

In formula (2B), 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 in the explanation of R ¹⁰⁷ in formula (2A'). 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 (2C), 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 in the explanation of R ¹⁰⁷ in formula (2A'). 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 (2D), 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 in the explanation of R ¹⁰⁷ in formula (2A').

Regarding the synthesis of a sulfonium salt containing an anion represented by formula (2D), see JP-A No. 2010-215608 and JP-A No. 2014-133723 for details.

Examples of the anion represented by formula (2D) 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 (2D) does not have fluorine at the α-position of the sulfo group, but has two trifluoromethyl groups at the β-position. and 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 (3) can also be suitably used.

In formula (3), R ²⁰¹ and R ²⁰² each independently represent 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 by combining R ¹⁰¹ and R ¹⁰² together with the sulfur atom to which they are bonded in the explanation of formula (2-1). .

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, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n- Alkyl groups such as octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group cyclic saturated hydrocarbyl groups, such as norbornyl group, tricyclo[5.2.1.0 ^2,6 ]decanyl group, adamantyl group; phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group 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, and anthracenyl group. In addition, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc., and some of the carbon atoms of these groups are substituted with oxygen atoms. atoms, sulfur atoms, nitrogen atoms, etc., and as a result, hydroxy groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate groups, lactone rings, It may contain a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like.

The hydrocarbylene group represented by R ²⁰³ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and heptane-1,6-diyl group. 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 alkanediyl groups, such as tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, etc. Group; cyclic saturated hydrocarbylene group such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl 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, isobutyl Examples include arylene groups such as naphthylene group, sec-butylnaphthylene group, and tert-butylnaphthylene group. In addition, some of the hydrogen atoms of these groups may be substituted with alkyl groups such as methyl, ethyl, propyl, n-butyl, tert-butyl, etc. Some of the carbon atoms in these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc. Optionally substituted with heteroatom-containing groups, such as hydroxy groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate groups, lactone rings, sultone rings, carboxylic anhydrides, haloalkyls It may also contain a group or the like. The hetero atom is preferably an oxygen atom.

In formula (3), 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 (3), X ^A , X ^B , X ^C and X ^D each independently represent 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 (3), k is an integer from 0 to 3.

As the photoacid generator represented by formula (3), one represented by the following formula (3') is preferable.

In formula (3'), 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 in the explanation of R ¹⁰⁷ in formula (2A'). x and y are each independently an integer of 0 to 5, and z is an integer of 0 to 4.

As the photoacid generator represented by the formula (3), the formula (2
) The same photoacid generators as those exemplified can be mentioned.

Among the photoacid generators, those containing an anion represented by formula (3A') or (3D) are particularly preferred because they have low acid diffusion and excellent solubility in resist solvents. Further, the compound represented by formula (3') has extremely low acid diffusion and is particularly preferable.

Furthermore, as the photoacid generator, a sulfonium salt or an iodonium salt having an anion containing 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 (4-1) or (4-2).

In formulas (4-1) and (4-2), r is an integer satisfying 1≦r≦3. s and t are integers satisfying 1≦s≦5, 0≦t≦3, and 1≦s+t≦5. s is preferably an integer satisfying 1≦s≦3, and more preferably 2 or 3. t is preferably an integer satisfying 0≦t≦2.

In formulas (4-1) and (4-2), X ^BI is an iodine atom or a bromine atom, and when s and/or r are 2 or more, they may be the same or different from each other.

In formulas (4-1) and (4-2), 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 (4-1) and (4-2), when r is 1, L ² is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when r is 2 or 3, it is a carbon It is a trivalent or tetravalent linking group of number 1 to 20, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

In formulas (4-1) and (4-2), 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 saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms, and a saturated hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, which may contain a group or an ether bond. A saturated hydrocarbylcarbonyloxy group or a saturated hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, or -N(R ^401A )-C(=O)-R ^401B or -N(R ^401A )-C(=O)-O- It is R ^401B . R ^401A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a halogen atom, a hydroxy group, an alkoxy 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; saturated hydrocarbylcarbonyloxy groups. R ^401B is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 carbon atoms; a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyl group having 2 to 6 carbon atoms; It may contain a hydrocarbylcarbonyl group or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group, and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When r and/or t are 2 or more, each R ⁴⁰¹ may be the same or different.

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

Rf ¹¹ to Rf ¹⁴ 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. Furthermore, Rf ¹¹ and Rf ¹² may be combined to form a carbonyl group. In particular, it is preferable that both Rf ¹³ and Rf ¹⁴ are fluorine atoms.

In formulas (4-1) and (4-2), R ⁴⁰² , R ⁴⁰³ , R ⁴⁰⁴ , R ⁴⁰⁵ and R ⁴⁰⁶ each independently represent a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a heteroatom. It is a hydrocarbyl group having 1 to 20 carbon atoms which may be contained. 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, alkynyl groups having 2 to 20 carbon atoms, and 3 to 20 carbon atoms. Examples include a cyclic unsaturated aliphatic hydrocarbyl group, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Further, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone group, a sulfone group, or a sulfonium salt-containing group. , some of the carbon atoms of these groups may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate group 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 combining R ¹⁰¹ and R ¹⁰² together with the sulfur atom to which they are bonded in the explanation of formula (2-1). .

Examples of the cation of the sulfonium salt represented by formula (4-1) include those exemplified as the cation of the sulfonium salt represented by formula (2-1). Further, as the cation of the iodonium salt represented by the formula (4-2), the same cations as those exemplified as the cation of the iodonium salt represented by the formula (2-2) can be mentioned.

Examples of the anion of the onium salt represented by formula (4-1) or (4-2) 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 does not contain a base polymer, the content of the additive acid generator is preferably 0.1 to 50 parts by weight, and 1 to 40 parts by weight, based on 100 parts by weight of the tertiary diester compound. Parts by mass are more preferred. When the positive resist material of the present invention contains a base polymer, the content of the additive acid generator is preferably 0.1 to 50 parts by weight based on a total of 100 parts by weight of the tertiary diester compound and the base polymer. , more preferably 1 to 40 parts by mass. Since the base polymer contains repeating units c1 to c3 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 such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone described in paragraphs [0144] to [0145] of JP-A-2008-111103. , 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, alcohols such as diacetone alcohol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene Ethers such as glycol monoethyl 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, 3-methoxypropionic acid Examples include methyl, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, esters such as propylene glycol mono tert-butyl ether acetate, lactones such as γ-butyrolactone, and mixed solvents thereof.

When the positive resist material of the present invention does not contain a base polymer, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and preferably 200 to 8,000 parts by mass, based on 100 parts by mass of the tertiary diester compound. part is more preferable. When the positive resist material of the present invention contains a base polymer, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and preferably 200 to 10,000 parts by mass, based on a total of 100 parts by mass of the tertiary diester compound and base polymer. 8,000 parts by mass is more preferred.

[Quencher]
A quencher may be added to the positive resist material of the present invention. 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 function as quenchers because they do not undergo a deprotection reaction.

Such quenchers include, for example, the compound represented by the following formula (5) (an onium salt of a sulfonic acid whose α-position is not fluorinated) and the compound represented by the following formula (6) (an onium salt of a sulfonic acid whose α-position is not fluorinated). onium salts).

In formula (5), 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, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n- Alkyl groups such as octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group cyclic saturated hydrocarbyl groups, such as norbornyl group, tricyclo[5.2.1.0 ^2,6 ]decanyl group, adamantyl group, adamantylmethyl group; vinyl group, allyl group, propenyl group, butenyl group, hexenyl group, etc. alkenyl group; cyclounsaturated aliphatic hydrocarbyl group such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group) group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methyl aryl groups such as naphthyl group, ethylnaphthyl group), dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.); heteroaryl groups such as thienyl group; benzyl group, 1-phenylethyl group, 2-phenylethyl group, etc. Examples include aralkyl groups.

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

In formula (6), R ⁵⁰² is a hydrocarbyl group having 1 to 40 carbon atoms and which may contain a heteroatom. 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- Also included are fluorine-containing alkyl groups such as fluoromethyl)-1-hydroxyethyl group; fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group.

In formulas (5) and (6), M ^q+ 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 (2-1). Further, as the iodonium cation, the same cations as those exemplified as the cation of the iodonium salt represented by formula (2-2) can be mentioned.

As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (7) can also be suitably used.

In formula (7), 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 atoms 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 (7), 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 ^D 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 group, 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 (7), R ⁶⁰² , R ⁶⁰³ and R ⁶⁰⁴ are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. be. 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, alkenyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms. Further, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone group, a sulfone group, or a sulfonium salt-containing group. , some of the carbon atoms of these groups may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate group or sulfonic acid ester bond. Furthermore, 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 (7) include those described in JP 2017-219836A. Iodine has 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. Sensitivity can be improved by

As the quencher, a biguanide salt of N-carbonylsulfonamide having an iodinated aromatic group represented by the following formula (8) can also be suitably used.

In formula (8), R ⁷⁰¹ is a hydrogen atom, a hydroxy group, 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, or fluorine. atom, chlorine atom, bromine atom, amino group, -N(R ^701A )-C(=O)-R ^701B or -N(R ^701A )-C(=O)-O-R ^701B , and R ^701A is , a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R ^701B is an aliphatic hydrocarbyl group having 1 to 8 carbon atoms.

In formula (8), R ⁷⁰² is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; an amino group, a nitro group, a cyano group, an alkyl group having 1 to 12 carbon atoms, It may be substituted with an alkoxy group having 1 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, an acyl group, an acyloxy group having 2 to 12 carbon atoms, a hydroxy group, or a halogen atom.

In formula (8), L ^E is a single bond or a divalent linking group having 1 to 20 carbon atoms, and the linking group includes an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone group, a lactam group, It may contain a carbonate group, a halogen atom, a hydroxy group or a carboxy group.

In formula (8), R ⁷¹¹ to R ⁷¹⁸ are a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, an alkynyl group having 2 to 24 carbon atoms, or an aryl group having 6 to 20 carbon atoms. A group containing an ester bond, ether bond, sulfide bond, sulfoxide group, carbonate group, carbamate group, sulfone group, halogen atom, amino group, amide bond, hydroxy group, thiol group or nitro group. Also, R ⁷¹¹ and R ⁷¹² , R ⁷¹² and R ⁷¹³ , R ⁷¹³ and R ⁷¹⁴ , R ⁷¹⁴ and R ⁷¹⁵ , R ⁷¹⁵ and R ⁷¹⁶ , R ⁷¹⁶ and R ⁷¹⁷ , or R ⁷¹⁷ and R ⁷¹⁸ may be bonded to each other to form a ring, and the ring may contain an ether bond.

Examples of the quencher include polymer-type quenchers described in JP-A No. 2008-239918. This improves the rectangularity of the resist after patterning by orienting it on the surface of the resist film after applying the resist material. 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 does not contain a base polymer, the content of the quencher is preferably 0 to 20 parts by weight, and 0.1 to 10 parts by weight, based on 100 parts by weight of the tertiary diester compound. More preferred. When the positive resist material of the present invention contains a base polymer, the content of the quencher is preferably 0 to 20 parts by mass, and 0.1 to 20 parts by mass, based on a total of 100 parts by mass of the tertiary diester compound and base polymer. 10 parts by mass is more preferred. Quenchers can be used alone or in combination of two or more.

[Other ingredients]
In addition to the above-mentioned components, surfactants, dissolution inhibitors, etc. are appropriately combined to form a positive resist material, so that the base polymer is dissolved in the developer by a catalytic reaction in the exposed area. Since the speed is accelerated, an extremely sensitive positive resist material can be obtained. In this case, the dissolution contrast and resolution of the resist film are high, there is exposure latitude, excellent process adaptability, and the pattern shape after exposure is good. Therefore, it is highly practical and can be very effective as a resist material for VLSI.

Examples of the surfactant include those described in paragraphs [0165] to [0166] of JP-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 does not contain a base polymer, the content of the surfactant is preferably 0.0001 to 10 parts by weight based on 100 parts by weight of the tertiary diester compound. When the positive resist material of the present invention contains a base polymer, the content of the surfactant is preferably 0.0001 to 10 parts by weight based on a total of 100 parts by weight of the tertiary diester compound and base polymer. Surfactants can be used alone or in combination of two or more.

By incorporating a dissolution inhibitor, it is possible to further increase the difference in dissolution rate between the exposed area and the unexposed area, and the 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 does not contain a base polymer, the content of the dissolution inhibitor is preferably 0 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the tertiary diester compound. preferable. When the positive resist material of the present invention contains a base polymer, the content of the dissolution inhibitor is preferably 0 to 50 parts by mass, and 5 to 40 parts by mass, based on a total of 100 parts by mass of the tertiary diester compound and base polymer. Parts by mass are more preferred. The dissolution inhibitors can be used alone or in combination of two or more.

A water repellency improver may be added to the positive resist material of the present invention in order to improve the water repellency of the surface of the resist film. The water repellency improver 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 acid evaporation during post-exposure bake (PEB) and preventing opening defects in hole patterns after development. When the positive resist material of the present invention does not contain a base polymer, the content of the water repellency improver is preferably 0 to 20 parts by weight, and 0.5 to 10 parts by weight, based on 100 parts by weight of the tertiary diester compound. part is more preferable. When the positive resist material of the present invention contains a base polymer, the content of the water repellency improver is preferably 0 to 20 parts by mass, and 0. More preferably 5 to 10 parts by mass. The water repellency improvers can be used alone or in combination of two or more.

Acetylene alcohols may be added to the positive resist material of the present invention. 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 does not contain a base polymer, the content of acetylene alcohol is preferably 0 to 5 parts by weight based on 100 parts by weight of the tertiary diester compound. When the positive resist material of the present invention contains a base polymer, the content of acetylene alcohols is preferably 0 to 5 parts by weight based on a total of 100 parts by weight of the tertiary diester compound and base polymer.

[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 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 using a developer. A method including a step of developing is mentioned.

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, X-rays, soft X-rays, excimer laser beams, γ-rays, and synchrotron radiation. When using ultraviolet rays, deep ultraviolet rays, EUV, X-rays, soft Irradiation is performed so that the amount 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 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, and particularly suitable for fine patterning by 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, 0.1 to 10% by weight, preferably 2 to 5% by weight of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutyl Using a developing solution of alkaline aqueous solution such as ammonium hydroxide (TBAH), for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, using a conventional method such as dip method, puddle method, spray method, etc. By developing by the method, the portions exposed to light are dissolved in the developer, and the portions not exposed are not dissolved, forming the desired positive pattern on the substrate.

Negative development can also be performed using the positive resist material to obtain a negative pattern 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 can 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 due to the diffusion of an acid catalyst from the resist layer 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 tertiary diester compound [Synthesis Example 1-1] Synthesis of diester compound 1 Diatrizoic acid and 2,5-dimethyl-3-hexyne-2,5-diol are subjected to an esterification reaction to form diester compound 1. was synthesized.

[Synthesis Examples 1-2 to 1-8] Synthesis of Diester Compounds 2 to 8 Synthesis Example 1- except that metrizoic acid, 3,5-diiodosalicylic acid, and 5-iodosalicylic acid were used instead of diatrizoic acid, respectively. Diester compounds 2 to 4 were synthesized in the same manner as in Example 1.
Also, instead of 2,5-dimethyl-3-hexyne-2,5-diol, α'-dihydroxy-1,4-diisopropylbenzene, α,α'-dihydroxy-1,3-diisopropylbenzene, 3, In the same manner as Synthesis Example 1-1 except that 6-dimethyl-4-octyne-3,6-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol were used. Diester compounds 5 to 8 were synthesized.

[2] Synthesis of base polymer [Synthesis Examples 2-1 to 2-3] Synthesis of Polymers 1 to 3 Each monomer is combined, copolymerized in THF, crystallized in methanol, and washed repeatedly with hexane. After that, it was isolated and dried to obtain base polymers (Polymers 1 to 3) having the compositions shown below. The composition of the obtained base polymer was confirmed by ¹ H-NMR, and the Mw and Mw/Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[3] Preparation of positive resist material and evaluation thereof [Examples 1 to 8, Comparative Example 1]
(1) Preparation of positive resist material A solution prepared by dissolving each component with the composition shown in Table 1 in a solvent containing 100 ppm of surfactant PolyFox PF-636 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)

・Acid generator: PAG-1

・Quencher: Q-1, Q-2

(2) EUV lithography evaluation Each resist material shown in Table 1 was applied on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed with a film thickness of 20 nm. A resist film having a thickness of 50 nm was prepared by spin-coating the resist film and pre-baking it at 100° C. for 60 seconds using a hot plate. This was exposed using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9/0.6, quadruple pole illumination, 46 nm pitch on the wafer, hole pattern mask with +20% bias) and 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. Further, dimensions of 50 holes were measured using a length measurement SEM (CG5000) manufactured by Hitachi High-Technologies Corporation, and CDU (dimensional variation 3σ) was determined.
The results are also listed in Table 1.

From the results in Table 1, the positive resist of the present invention contains a group containing an aromatic ring substituted with an iodine atom and a tertiary diester compound having two ester bonds to which a tertiary carbon atom is bonded in the molecule. The material had high sensitivity and good CDU.

Claims (12)

A positive resist material comprising a group containing an aromatic ring substituted with an iodine atom and a tertiary diester compound having two ester bonds bonded to a tertiary carbon atom in the molecule, and an acid generator. ,
A positive resist material, wherein the tertiary diester compound is represented by the following formula (1).

(In the formula, R ^1A and R ^1B are each independently a hydroxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. , a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, -N(R ^1C )-C(=O)-R ^1D or -N( R ^1C )-C(=O)-O-R ^1D . R ^1C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^1D is an aliphatic hydrocarbyl group having 1 to 8 carbon atoms. In addition, the saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyl carbonyloxy group, saturated hydrocarbylsulfonyloxy group, and aliphatic hydrocarbyl group may have some or all of their hydrogen atoms substituted with halogen atoms. Often, an ether bond or ester bond may be present between the carbon atoms.
R ^2A and R ^2B are each independently a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms.
R ³ to R ⁶ are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms, and R ³ and R ⁴ may be bonded to each other to form a ring with the carbon atom to which they are bonded. , R ⁵ and R ⁶ may be bonded to each other to form a ring together with the carbon atom to which they are bonded.
R ⁷ is an aliphatic hydrocarbylene group having 2 to 10 carbon atoms or a phenylene group.
m, n, p and q are 0≦m≦5, 0≦n≦5, 0≦p≦5, 0≦q≦5, 0≦m+p≦5, 0≦n+q≦5 and 1≦m+n≦10 It is an integer that satisfies the following. ) The positive resist material according to claim 1 , further comprising a base polymer. A positive resist material comprising a base polymer and a tertiary diester compound having two ester bonds bonded to a group containing an aromatic ring substituted with an iodine atom and a tertiary carbon atom in the molecule,
The tertiary diester compound is represented by the following formula (1),
A positive resist material, wherein the base polymer contains a repeating unit represented by any of the following formulas (c1) to (c3).

(In the formula, R ^1A and R ^1B each independently represents a hydroxy group, 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, and a saturated hydrocarbyl group having 1 to 4 carbon atoms. Sulfonyloxy group, fluorine atom, chlorine atom, bromine atom, amino group, nitro group, cyano group, -N(R ^1C )-C(=O)-R ^1D or -N(R ^1C )-C(=O)-OR ^1D It is. R ^1C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^1D is an aliphatic hydrocarbyl group having 1 to 8 carbon atoms. Further, in the saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbylsulfonyloxy group, and aliphatic hydrocarbyl group, some or all of the hydrogen atoms thereof may be substituted with a halogen atom, An ether bond or ester bond may exist between carbon and carbon atoms.
R ^2A and R ^2B are each independently a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms.
R ³ ～R ⁶ are each independently a saturated hydrocarbyl group having 1 to 8 carbon atoms, and R ³ and R ^Four may be bonded to each other to form a ring together with the carbon atoms to which they are bonded, and R ^Five and R ⁶ may be bonded to each other to form a ring together with the carbon atoms to which they are bonded.
R ⁷ is an aliphatic hydrocarbylene group or phenylene group having 2 to 10 carbon atoms.
m, n, p and q are 0≦m≦5, 0≦n≦5, 0≦p≦5, 0≦q≦5, 0≦m+p≦5, 0≦n+q≦5 and 1≦m+n≦10 It is an integer that satisfies the following. )

(In the formula, R ^A are each independently a hydrogen atom or a methyl group.
Y ¹ is a single bond, phenylene group, naphthylene group, -O-Y ¹¹ -, -C(=O)-O-Y ¹¹ -or-C(=O)-NH-Y ¹¹ - is. Y 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 does not contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. It's okay to stay.
Y ² is a single bond or an ester bond.
Y ³ is a single bond, -Y ³¹ -C(=O)-O-, -Y ³¹ -O- or -Y ³¹ -OC(=O)-. Y ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and contains a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Good too.
Y ^Four is a single bond, a methylene group or a 2,2,2-trifluoro-1,1-ethanediyl group.
Y ^Five is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, -O-Y ⁵¹ -, -C(=O)-O-Y ⁵¹ -or-C(=O)-NH-Y ⁵¹ - is. Y ⁵¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, even if it contains a carbonyl group, an ester bond, an ether bond, or a hydroxy group. good.
Rf ¹ and Rf ² are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one is a fluorine atom.
R ^{twenty one} ～R ²⁸ are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a C1-20 hydrocarbyl group which may contain a heteroatom. Also, R ^{twenty three} and R ^{twenty four} 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. ) 2. The base polymer comprises a repeating unit in which a hydrogen atom of a carboxy group is substituted with an acid-labile group and/or a repeating unit in which a hydrogen atom of a phenolic hydroxy group is substituted with an acid-labile group. 3. The positive resist material described in 3. The repeating unit in which the hydrogen atom of the carboxy group is substituted with an acid-labile group and the repeating unit in which the hydrogen atom of the phenolic hydroxy group is substituted with an acid-labile group are each represented by the following formula (a1). The positive resist material according to claim 4, which is a repeating unit and a repeating unit represented by the following formula (a2).

(In the formula, R ^A is each independently 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 containing an ester bond, ether bond, or lactone ring.
X ² is a single bond, an ester bond or an amide bond.
X ³ is a single bond, an ether bond or an ester bond.
R ¹¹ and R ¹² are acid labile groups.
R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms.
R ¹⁴ is a single bond or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and some of its carbon atoms 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 group, a thiocarbonate group, 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 2 to 5, which contains a repeating unit b containing an adhesive group selected from C(=O)-S- and -OC(=O)-NH-. . 3. The positive resist material according to claim 2 , wherein the base polymer further contains a repeating unit represented by one of the following formulas (c1) to (c3).

(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, -O-Y ¹¹ -, -C(=O)-O-Y ¹¹ - or -C(=O)-NH-Y ¹¹ -. Y 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.
Y ² is a single bond or an ester bond.
Y ³ is a single bond, -Y ³¹ -C(=O)-O-, -Y ³¹ -O-, or -Y ³¹ -O-C(=O)-. Y ³¹ is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and does not contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. It's okay to stay.
Y ⁴ is a single bond, a methylene group or a 2,2,2-trifluoro-1,1-ethanediyl group.
Y ⁵ is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, -O-Y ⁵¹ -, -C(=O)-O-Y ⁵¹ - or -C(=O)-NH- Y ⁵¹ -. Y ⁵¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and contains a carbonyl group, an ester bond, an ether bond, or a hydroxy group. You can stay there.
Rf ¹ and Rf ² are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one is a fluorine atom.
R ²¹ to R ²⁸ are each independently a fluorine atom, chlorine atom, bromine atom, iodine atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. Further, 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 any one of claims 1 to 7 , further comprising an organic solvent. The positive resist material according to claim 1, further comprising a quencher . The positive resist material according to any one of claims 1 to 9 , 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 10 , a step of exposing the resist film to high energy radiation, and a step of exposing the exposed resist film to a high energy beam. , a pattern forming method comprising a step of developing using a developer. 12. The pattern forming method according to claim 11 , 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.