WO2025143126A1 - Plasma-treated resist underlayer film, composition for forming resist underlayer film, method for producing plasma-treated resist underlayer film, and laminate - Google Patents

Abstract

This plasma-treated resist underlayer film contains resin (I) containing a structural unit represented by formula (1). (In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.)

Description

Plasma-treated resist underlayer film, composition for forming resist underlayer film, method for producing plasma-treated resist underlayer film, and laminate

The present invention relates to a plasma-treated resist underlayer film, a composition for forming a resist underlayer film, a method for producing a plasma-treated resist underlayer film, and a laminate.

In the manufacture of semiconductor devices, microfabrication has been performed by lithography using a resist composition. The microfabrication is a processing method in which a thin film of a photoresist composition is formed on a semiconductor substrate such as a silicon wafer, and then the thin film is irradiated with active light such as ultraviolet light through a mask pattern on which a device pattern is drawn, developed, and the substrate is etched using the obtained photoresist pattern as a protective film, thereby forming fine irregularities on the substrate surface corresponding to the photoresist pattern. In recent years, the integration density of semiconductor devices has increased, and in addition to the conventionally used i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm), the practical use of EUV light (wavelength 13.5 nm) or EB (electron beam) is being considered for cutting-edge microfabrication. As a result, poor resist pattern formation due to the influence of the semiconductor substrate, etc. has become a major problem. In order to solve this problem, a method of providing a resist underlayer film between the resist and the semiconductor substrate has been widely considered.

Patent Document 1 discloses a composition for forming an underlayer film for lithography that contains a naphthalene ring having a halogen atom. Patent Document 2 discloses a halogenated anti-reflective film. Patent Document 3 discloses a composition for forming a resist underlayer film.

In this technological situation, a method for modifying the surface of a film using plasma is known. For example, Patent Document 4 discloses a technology for producing a cured film by irradiating a conductive polymer precursor such as polythiophene with plasma to polymerize it in order to obtain a film with excellent heat resistance and moisture resistance.

International Publication No. WO 2006/003850 Special Publication No. 2005-526270 International Publication No. 2020/111068 Patent No. 5746670

The properties required for the resist underlayer film include, for example, no intermixing with the resist film formed on the upper layer (being insoluble in a resist solvent), excellent etching resistance, and enhanced film hardness and density.
The present invention has been made in consideration of the above circumstances, and has an object to provide a composition for forming a resist underlayer film that is capable of forming a resist underlayer film having excellent etching resistance and increased film hardness and film density, as well as a plasma-treated resist underlayer film, a method for producing a plasma-treated resist underlayer film, and a laminate using the composition for forming a resist underlayer film.

The inventors conducted extensive research to solve the above problems, and as a result, discovered that they could solve the above problems, leading to the completion of the present invention, which has the following gist:

（式（１）中、Ｃは、芳香族環を有する構造を表し、Ｄは、１つ以上の炭素原子を有する構造を表し、＊は結合手を表す。）
　［２］　前記樹脂（Ｉ）が、前記式（１）における前記Ｃの前記芳香族環を構成する炭素原子と、前記Ｄの炭素原子との間に共有結合を生成する反応によって得られた樹脂である、［１］に記載のプラズマ処理済レジスト下層膜。
　［３］　前記樹脂（Ｉ）が、複合単位構造を有する樹脂（Ｇ）を含み、
　前記複合単位構造が、芳香族環を有する単位構造（Ａ）と、１つ以上の炭素原子を有する単位構造（Ｂ）と、を有し、
　前記樹脂（Ｇ）が、前記単位構造（Ａ）の前記芳香族環を構成する炭素原子と、前記単位構造（Ｂ）中の炭素原子との間に共有結合を生成する反応によって得られた樹脂であり、
　前記単位構造（Ａ）が芳香族環を有する骨格を有し、前記骨格は、芳香族アミン骨格、含窒素芳香族複素環骨格、及び芳香族環に結合したヒドロキシ基を有する芳香族環骨格の少なくともいずれかの骨格である、［１］又は［２］に記載のプラズマ処理済レジスト下層膜。
　［４］　ラマン分光分析によるＧバンドとＤバンドの強度比Ｉｇ／Ｉｄが０．１～１０．０である、［１］から［３］のいずれかに記載のプラズマ処理済レジスト下層膜。
　［５］　膜密度が１．０～２．５ｇ／ｃｍ^３である、［１］から［４］のいずれかに記載のプラズマ処理済レジスト下層膜。
　［６］　波長１９３ｎｍにおける屈折率が１．３～２．５又は光学吸収係数が０．２～１．０であるか、波長６３３ｎｍにおける屈折率が１．５～３．５又は光学吸収係数が０～０．２である、［１］から［５］のいずれかに記載のプラズマ処理済レジスト下層膜。
　［７］　プラズマ処理前のプラズマ処理前レジスト下層膜の赤外分光法による炭素－炭素二重結合の吸収ピークのピーク面積に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の赤外分光法による炭素－炭素二重結合の吸収ピークのピーク面積が１．０１倍以上である、［１］から［６］のいずれかに記載のプラズマ処理済レジスト下層膜。
　［８］　弾性率が５０ＧＰａ以上である、［１］から［７］のいずれかに記載のプラズマ処理済レジスト下層膜。
　［９］　［１］から［８］のいずれかに記載のプラズマ処理済レジスト下層膜を形成するためのレジスト下層膜形成用組成物であって、前記樹脂（Ｉ）及び溶剤を含む、レジスト下層膜形成用組成物。
　［１０］　前記溶剤が、ヒドロキシ基を有するカルボン酸、直鎖又は環式のアルキルケトン、環状ラクトン、アルキレングリコールモノアルキルエーテル、アルキレングリコールモノアルキルエーテルのモノカルボン酸エステル及びアルキレングリコールモノアルキルエーテルのアルコキシカルボン酸エステルからなる群より選択される少なくとも一種を含む、［９］に記載のレジスト下層膜形成用組成物。
　［１１］　前記溶剤が、沸点１６０℃以上の溶剤を含む、［９］又は［１０］に記載のレジスト下層膜形成用組成物。
　［１２］　酸、その塩及び酸発生剤からなる群より選択される少なくとも一種を更に含む、［９］から［１１］のいずれかに記載のレジスト下層膜形成用組成物。
　［１３］　架橋剤を更に含む、［９］から［１２］のいずれかに記載のレジスト下層膜形成用組成物。
　［１４］　界面活性剤を更に含む、［９］から［１３］のいずれかに記載のレジスト下層膜形成用組成物。
　［１５］　半導体基板の上に、レジスト下層膜形成用組成物を用いて塗布膜を形成する工程と、
　前記塗布膜をプラズマ処理することにより、ラマン分光分析によるＧバンドとＤバンドの強度比Ｉｇ／Ｉｄが増加するか、赤外分光法による炭素－炭素二重結合の吸収ピークのピーク面積が増加するか、波長１９３ｎｍ若しくは波長６３３ｎｍにおける屈折率が増加するか、又は波長１９３ｎｍにおける光学吸収係数が減少する、プラズマ処理済レジスト下層膜を形成する工程とを含み、
　前記レジスト下層膜形成用組成物は、下記式（１）で表される構造単位を含む樹脂（Ｉ）及び溶剤を含む、プラズマ処理済レジスト下層膜の製造方法。

（式（１）中、Ｃは、芳香族環を有する構造を表し、Ｄは、１つ以上の炭素原子を有する構造を表し、＊は結合手を表す。）
　［１６］　前記樹脂（Ｉ）が、前記式（１）における前記Ｃの前記芳香族環を構成する炭素原子と、前記Ｄの炭素原子との間に共有結合を生成する反応によって得られた樹脂である、［１５］に記載のプラズマ処理済レジスト下層膜の製造方法。
　［１７］　前記樹脂（Ｉ）が、複合単位構造を有する樹脂（Ｇ）を含み、
　前記複合単位構造が、芳香族環を有する単位構造（Ａ）と、１つ以上の炭素原子を有する単位構造（Ｂ）と、を有し、
　前記樹脂（Ｇ）が、前記単位構造（Ａ）の前記芳香族環を構成する炭素原子と、前記単位構造（Ｂ）中の炭素原子との間に共有結合を生成する反応によって得られた樹脂であり、
　前記単位構造（Ａ）が芳香族環を有する骨格を有し、前記骨格は、芳香族アミン骨格、含窒素芳香族複素環骨格、及び芳香族環に結合したヒドロキシ基を有する芳香族環骨格の少なくともいずれかの骨格である、［１５］又は［１６］に記載のプラズマ処理済レジスト下層膜の製造方法。
　［１８］　プラズマ処理前のプラズマ処理前レジスト下層膜の前記強度比Ｉｇ／Ｉｄに対し、プラズマ処理後のプラズマ処理済レジスト下層膜の前記強度比Ｉｇ／Ｉｄが１．０１倍以上である、［１５］から［１７］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［１９］　プラズマ処理前のプラズマ処理前レジスト下層膜の硬度に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の硬度が１．０１倍以上である、［１５］から［１８］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２０］　プラズマ処理前のプラズマ処理前レジスト下層膜の膜密度に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の膜密度が１．０１倍以上である、［１５］から［１９］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２１］　プラズマ処理前のプラズマ処理前レジスト下層膜の屈折率に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の波長１９３ｎｍにおける屈折率が１．０１倍以上若しくはプラズマ処理前のプラズマ処理前レジスト下層膜の光学吸収係数に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の波長１９３ｎｍにおける光学吸収係数が０．９９倍以下、又はプラズマ処理前のプラズマ処理前レジスト下層膜の屈折率に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の波長６３３ｎｍにおける屈折率が１．０１倍以上である、［１５］から［２０］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２２］　プラズマ処理前のプラズマ処理前レジスト下層膜の赤外分光法による炭素－炭素二重結合の吸収ピークのピーク面積に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の赤外分光法による炭素－炭素二重結合の吸収ピークのピーク面積が１．０１倍以上である、［１５］から［２１］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２３］　プラズマ処理前のプラズマ処理前レジスト下層膜の弾性率に対し、プラズマ処理後のプラズマ処理済レジスト下層膜の弾性率が１．０１倍以上である、［１５］から［２２］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２４］　プラズマ処理前のプラズマ処理前レジスト下層膜のエッチング耐性に対し、プラズマ処理後のプラズマ処理済レジスト下層膜のエッチング耐性が１．０１倍以上である、［１５］から［２３］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２５］　前記プラズマ処理に用いるガスが、少なくとも希ガス、窒素、及び水素を含む、［１５］から［２４］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２６］　前記プラズマ処理の後、前記プラズマ処理済レジスト下層膜が形成された前記半導体基板を４００℃以上で焼成する工程を更に含む、［１５］から［２５］のいずれかに記載のプラズマ処理済レジスト下層膜の製造方法。
　［２７］　半導体基板と、
　［１］から［８］のいずれかに記載のプラズマ処理済レジスト下層膜と、を備える積層体。 That is, the present invention includes the following aspects.
[1] A plasma-treated resist underlayer film comprising a resin (I) containing a structural unit represented by the following formula (1):

(In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.)
[2] The plasma-treated resist underlayer film according to [1], wherein the resin (I) is a resin obtained by a reaction to form a covalent bond between a carbon atom constituting the aromatic ring of the C in the formula (1) and a carbon atom of the D.
[3] The resin (I) contains a resin (G) having a composite unit structure,
the composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms,
the resin (G) is a resin obtained by a reaction for forming a covalent bond between a carbon atom constituting the aromatic ring of the unit structure (A) and a carbon atom in the unit structure (B),
The plasma-treated resist underlayer film according to [1] or [2], wherein the unit structure (A) has a skeleton having an aromatic ring, and the skeleton is at least any one of an aromatic amine skeleton, a nitrogen-containing aromatic heterocyclic skeleton, and an aromatic ring skeleton having a hydroxy group bonded to the aromatic ring.
[4] The plasma-treated resist underlayer film according to any one of [1] to [3], wherein the intensity ratio Ig/Id of G band to D band as determined by Raman spectroscopy is 0.1 to 10.0.
[5] The plasma-treated resist underlayer film according to any ^one of [1] to [4], having a film density of 1.0 to 2.5 g/cm3.
[6] The plasma-treated resist underlayer film according to any one of [1] to [5], wherein the refractive index at a wavelength of 193 nm is 1.3 to 2.5 or the optical absorption coefficient is 0.2 to 1.0, or the refractive index at a wavelength of 633 nm is 1.5 to 3.5 or the optical absorption coefficient is 0 to 0.2.
[7] The plasma-treated resist underlayer film according to any one of [1] to [6], wherein the peak area of an absorption peak of a carbon-carbon double bond, as measured by infrared spectroscopy, of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more larger than the peak area of an absorption peak of a carbon-carbon double bond, as measured by infrared spectroscopy, of the pre-plasma-treated resist underlayer film before the plasma treatment.
[8] The plasma-treated resist underlayer film according to any one of [1] to [7], having an elastic modulus of 50 GPa or more.
[9] A composition for forming a resist underlayer film for forming the plasma-treated resist underlayer film according to any one of [1] to [8], comprising the resin (I) and a solvent.
[10] The composition for forming a resist underlayer film according to [9], wherein the solvent contains at least one selected from the group consisting of a carboxylic acid having a hydroxy group, a linear or cyclic alkyl ketone, a cyclic lactone, an alkylene glycol monoalkyl ether, a monocarboxylic acid ester of an alkylene glycol monoalkyl ether, and an alkoxycarboxylic acid ester of an alkylene glycol monoalkyl ether.
[11] The composition for forming a resist underlayer film according to [9] or [10], wherein the solvent contains a solvent having a boiling point of 160° C. or higher.
[12] The composition for forming a resist underlayer film according to any one of [9] to [11], further comprising at least one selected from the group consisting of an acid, a salt thereof, and an acid generator.
[13] The composition for forming a resist underlayer film according to any one of [9] to [12], further comprising a crosslinking agent.
[14] The composition for forming a resist underlayer film according to any one of [9] to [13], further comprising a surfactant.
[15] A step of forming a coating film on a semiconductor substrate using a composition for forming a resist underlayer film;
and forming a plasma-treated resist underlayer film, in which the coating film is subjected to a plasma treatment to increase the intensity ratio Ig/Id of G band to D band as determined by Raman spectroscopy, increase the peak area of the absorption peak of a carbon-carbon double bond as determined by infrared spectroscopy, increase the refractive index at a wavelength of 193 nm or 633 nm, or decrease the optical absorption coefficient at a wavelength of 193 nm;
The composition for forming a resist underlayer film comprises a resin (I) having a structural unit represented by the following formula (1) and a solvent:

(In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.)
[16] The method for producing a plasma-treated resist underlayer film according to [15], wherein the resin (I) is a resin obtained by a reaction for forming a covalent bond between a carbon atom constituting the aromatic ring of the C in the formula (1) and a carbon atom of the D.
[17] The resin (I) contains a resin (G) having a composite unit structure,
the composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms,
the resin (G) is a resin obtained by a reaction for forming a covalent bond between a carbon atom constituting the aromatic ring of the unit structure (A) and a carbon atom in the unit structure (B),
The method for producing a plasma-treated resist underlayer film according to [15] or [16], wherein the unit structure (A) has a skeleton having an aromatic ring, and the skeleton is at least any one of an aromatic amine skeleton, a nitrogen-containing aromatic heterocyclic skeleton, and an aromatic ring skeleton having a hydroxy group bonded to the aromatic ring.
[18] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [17], wherein the intensity ratio Ig/Id of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more relative to the intensity ratio Ig/Id of the pre-plasma-treated resist underlayer film before the plasma treatment.
[19] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [18], wherein the hardness of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more greater than the hardness of the pre-plasma-treated resist underlayer film before the plasma treatment.
[20] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [19], wherein the film density of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more higher than the film density of the pre-plasma-treated resist underlayer film before the plasma treatment.
[21] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [20], wherein the refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 193 nm is 1.01 times or more relative to the refractive index of the pre-plasma-treated resist underlayer film before the plasma treatment, or the optical absorption coefficient of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 193 nm is 0.99 times or less relative to the optical absorption coefficient of the pre-plasma-treated resist underlayer film before the plasma treatment, or the refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 633 nm is 1.01 times or more relative to the refractive index of the pre-plasma-treated resist underlayer film before the plasma treatment.
[22] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [21], wherein the peak area of an absorption peak of a carbon-carbon double bond, as determined by infrared spectroscopy, of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more larger than the peak area of an absorption peak of a carbon-carbon double bond, as determined by infrared spectroscopy, of the pre-plasma-treated resist underlayer film before the plasma treatment.
[23] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [22], wherein the elastic modulus of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more greater than the elastic modulus of the pre-plasma-treated resist underlayer film before the plasma treatment.
[24] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [23], wherein the etching resistance of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more higher than the etching resistance of the pre-plasma-treated resist underlayer film before the plasma treatment.
[25] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [24], wherein a gas used in the plasma treatment contains at least a rare gas, nitrogen, and hydrogen.
[26] The method for producing a plasma-treated resist underlayer film according to any one of [15] to [25], further comprising a step of baking the semiconductor substrate on which the plasma-treated resist underlayer film has been formed at 400° C. or higher after the plasma treatment.
[27] A semiconductor substrate;
A laminate comprising: a plasma-treated resist underlayer film according to any one of [1] to [8].

The present invention provides a composition for forming a resist underlayer film that is capable of forming a resist underlayer film with excellent etching resistance and increased film hardness and density, as well as a plasma-treated resist underlayer film, a method for producing a plasma-treated resist underlayer film, and a laminate using the composition for forming a resist underlayer film.

　式（１）中、Ｃは、芳香族環を有する構造を表し、Ｄは、１つ以上の炭素原子を有する構造を表し、＊は結合手を表す。
　構造Ｃ、構造Ｄについては、後述する。 [Plasma-treated resist underlayer film]
(Resin (I))
The plasma-treated resist underlayer film of the present invention contains a resin (I) that includes a structural unit represented by the following formula (1).

In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.
Structures C and D will be described later.

The resin (I) may contain a structural unit represented by the following formula (2).
In formula (2), ^X1 and ^X2 each independently represent a _ROCH2- group (R is a saturated or unsaturated linear or branched _C1 - _C20 aliphatic hydrocarbon group, a C3-C20 alicyclic hydrocarbon group, a hydrogen atom, or a mixture thereof, which may be substituted with a phenyl group, a _naphthyl group, or _{an anthracenyl} group and may be interrupted with an oxygen atom or a carbonyl group), and * represents a bond.

The monovalent organic group R is preferably a saturated or unsaturated, linear or branched C 1 -C 20 aliphatic hydrocarbon group, a C _{3 -C 20} alicyclic hydrocarbon group, or a mixture thereof, which may be substituted with a phenyl group, a naphthyl group, or an anthracenyl group and may be interrupted with an oxygen atom or a _carbonyl group. The term "mixed" means that the multiple ROCH ₂ - groups present in a single unit structure may be different, and also means that the ROCH ₂ - groups in two or more unit structures may be different.

Typical examples of the saturated aliphatic hydrocarbon group include linear or branched alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-methyl-n-butyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl, n-hexyl, 1-methyl-n-pentyl, and 2-methyl-n-pentyl. , 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, and 1-methoxy-2-propyl group.

Cyclic alkyl groups can also be used. For example, cyclic alkyl groups having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, 1-methylcyclopropyl, 2-methylcyclopropyl, cyclopentyl, 1-methylcyclobutyl, 2-methylcyclobutyl, 3-methylcyclobutyl, 1,2-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 1-ethylcyclopropyl, 2-ethylcyclopropyl, cyclohexyl, 1-methylcyclopentyl, 2-methylcyclopentyl, 3-methylcyclopentyl, 1-ethylcyclobutyl, 2-ethylcyclobutyl, 3-ethyl ...,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 2,3 Examples of the cyclobutyl group include 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group, and 2-ethyl-3-methyl-cyclopropyl group.

Typical unsaturated aliphatic hydrocarbon groups are alkenyl groups having 2 to 20 carbon atoms, such as ethenyl, 1-propenyl, 2-propenyl, 1-methyl-1-ethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 2 ... a 4-pentenyl group, a 1-n-propylethenyl group, a 1-methyl-1-butenyl group, a 1-methyl-2-butenyl group, a 1-methyl-3-butenyl group, a 2-ethyl-2-propenyl group, a 2-methyl-1-butenyl group, a 2-methyl-2-butenyl group, a 2-methyl-3-butenyl group, a 3-methyl-1-butenyl group, a 3-methyl-2-butenyl group, a 3-methyl-3-butenyl group, a 1,1-dimethyl-2-propenyl group, a 1-i-propylethenyl group, a 1,2-dimethyl ethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl -2-pentenyl group, 2-methyl-3-pentenyl group, 2-methyl-4-pentenyl group, 2-n-propyl-2-propenyl group, 3-methyl-1-pentenyl group, 3-methyl-2-pentenyl group, 3-methyl-3-pentenyl group, 3-methyl-4-pentenyl group, 3-ethyl-3-butenyl group, 4-methyl-1-pentenyl group, 4-methyl-2-pentenyl group, 4-methyl-3-pentenyl group, 4-methyl-4-pentenyl group, 1,1-dimethyl-2-butenyl group, nyl group, 1,1-dimethyl-3-butenyl group, 1,2-dimethyl-1-butenyl group, 1,2-dimethyl-2-butenyl group, 1,2-dimethyl-3-butenyl group, 1-methyl-2-ethyl-2-propenyl group, 1-s-butylethenyl group, 1,3-dimethyl-1-butenyl group, 1,3-dimethyl-2-butenyl group, 1,3-dimethyl-3-butenyl group, 1-i-butylethenyl group, 2,2-dimethyl-3-butenyl group, 2,3-dimethyl-1-butenyl group, 2,3-dimethyl-2-butenyl group, 2,3-dimethyl-3-butenyl group, 2-i-propyl-2-propenyl group, 3,3-dimethyl-1-butenyl group, 1-ethyl-1-butenyl group, 1-ethyl-2-butenyl group, 1-ethyl-3-butenyl group, 1-n-propyl-1-propenyl group, 1-n-propyl-2-propenyl group, 2-ethyl-1-butenyl group, 2-ethyl-2-butenyl group, 2-ethyl-3-butenyl group, 1,1,2-trimethyl-2-propenyl group, a 1-tert-butylethenyl group, a 1-methyl-1-ethyl-2-propenyl group, a 1-ethyl-2-methyl-1-propenyl group, a 1-ethyl-2-methyl-2-propenyl group, a 1-i-propyl-1-propenyl group, a 1-i-propyl-2-propenyl group, a 1-methyl-2-cyclopentenyl group, a 1-methyl-3-cyclopentenyl group, a 2-methyl-1-cyclopentenyl group, a 2-methyl-2-cyclopentenyl group, a 2-methyl-3-cyclopentenyl group, a Examples include a 2-methyl-4-cyclopentenyl group, a 2-methyl-5-cyclopentenyl group, a 2-methylene-cyclopentyl group, a 3-methyl-1-cyclopentenyl group, a 3-methyl-2-cyclopentenyl group, a 3-methyl-3-cyclopentenyl group, a 3-methyl-4-cyclopentenyl group, a 3-methyl-5-cyclopentenyl group, a 3-methylene-cyclopentyl group, a 1-cyclohexenyl group, a 2-cyclohexenyl group, and a 3-cyclohexenyl group.

The above-mentioned saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, and cyclic alkyl groups may be interrupted once or more than once by oxygen atoms and/or carbonyl groups.

Resin (I) can be synthesized by polymerizing a compound having a methoxymethyl group and optionally having a phenolic hydroxyl group, a compound that reacts with the methoxymethyl group to give a ROCH ₂ - group other than a methoxymethyl group (R is a monovalent organic group, a hydrogen atom or a mixture of these), and, if necessary, a compound containing a functional group that can serve as a linking group (e.g., an aldehyde, a ketone, ROCH ₂ -Ar-CH ₂ OR (R is a monovalent organic group, a hydrogen atom or a mixture of these)) in the presence of an acid catalyst (e.g., a sulfonic acid compound).

An example of a compound having a methoxymethyl group and optionally having a phenolic hydroxyl group that is used in the synthesis of resin (I) is 3,3',5,5'-tetramethoxymethyl-4,4'-dihydroxybiphenyl.

Resin (I) includes resin (G) described below.
Structure C in resin (I) corresponds to unit structure (A) in resin (G), and structure D in resin (I) corresponds to unit structure (B) in resin (G).
The resin (G) will be described below.

<Resin (G)>
The resin (G) has a composite unit structure.
The composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms.
The resin (G) is preferably a resin obtained by a reaction forming a covalent bond between a carbon atom constituting the aromatic ring of the unit structure (A) and a carbon atom in the unit structure (B).
In this specification, resin (G) may be referred to as a "novolak resin."

The unit structure (A) has, for example, at least one of an oxygen atom constituting an aromatic ring, a sulfur atom constituting an aromatic ring, an oxygen atom bonded to an aromatic ring, a nitrogen atom constituting an aromatic ring, and a nitrogen atom bonded to an aromatic ring.
The unit structure (A) does not have a heteroatom, for example, as an atom constituting an aromatic ring or an atom bonded to the aromatic ring.

The unit structure (B) is, for example, a unit structure derived from an aldehyde compound or an aldehyde equivalent.
An aldehyde equivalent is an organic compound capable of covalently bonding with an aromatic ring, and is an organic compound having a ketone group; an acetal group; a ketal group; a hydroxyl group or an alkoxy group bonded to a secondary or tertiary carbon atom; a hydroxyl group, an alkoxy group or a halo group bonded to the α-carbon atom of an alkylaryl group; or a carbon-carbon unsaturated bond.

I. Definitions of Terms
In this specification, the definitions of main terms related to the novolac resin, which is one embodiment of the present invention, are explained below. Unless otherwise specified, the following definitions of each term apply to the novolac resin.

(I-1) "Novolac resin"
The term "novolac resin" is used in a broad sense to include not only phenol-formaldehyde resins (so-called novolac-type phenolic resins) and aniline-formaldehyde resins (so-called novolac-type aniline resins) in the narrow sense, but also resins formed by forming a covalent bond (substitution reaction, addition reaction, condensation reaction, addition-condensation reaction, etc.) between an organic compound having a functional group capable of forming a covalent bond with an aromatic ring [e.g., an aldehyde group; a ketone group; an acetal group; a ketal group; a hydroxyl group or an alkoxy group bonded to a secondary or tertiary carbon atom; a hydroxyl group, an alkoxy group or a halo group bonded to an α-position carbon atom (e.g., a benzylic carbon atom) of an alkylaryl group; a carbon-carbon unsaturated bond such as in divinylbenzene or dicyclopentadiene] and an aromatic ring in a compound having an aromatic ring (preferably having heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms as atoms constituting the aromatic ring or atoms bonded to the aromatic ring) in the presence of an acid catalyst or under reaction conditions equivalent thereto.

Therefore, the novolak resin referred to in this specification is a resin formed by linking multiple compounds having aromatic rings together, with an organic compound containing a carbon atom derived from the functional group (sometimes referred to as a "linking carbon atom") forming a covalent bond with an aromatic ring in a compound having an aromatic ring via the linking carbon atom.

In this specification, the terms unit structure (A) and unit structure (B) are used to refer to the unit structures that make up "novolac resin." Unit structure (A) is a unit structure derived from a compound that has an aromatic ring. Unit structure (B) is a unit structure derived from a compound that has a functional group that allows for covalent bonding with the aromatic ring of unit structure (A).

(I-2) "Residue"
The term "residue" refers to an organic group in which a hydrogen atom bonded to a carbon atom or a heteroatom (such as a nitrogen atom, an oxygen atom, or a sulfur atom) is replaced with a bond, and may be a monovalent or polyvalent group. For example, if one hydrogen atom is replaced with one bond, it becomes a monovalent organic group, and if two hydrogen atoms are replaced with bonds, it becomes a divalent organic group.

(I-3) "Aromatic ring" (aromatic group, aryl group, arylene group)
The term "aromatic ring" refers to a concept that includes aromatic hydrocarbon rings, aromatic heterocycles, and residues thereof (sometimes called "aromatic groups,""arylgroups" (in the case of monovalent groups), or "arylene groups" (in the case of divalent groups)), and includes not only monocyclic (aromatic monocycles) but also polycyclic (aromatic polycycles). In the case of polycyclic rings, at least one monocycle is an aromatic monocycle, but the remaining monocycles that form a condensed ring with the aromatic monocycle may be a monocyclic heterocycle (heteromonocycle) or a monocyclic alicyclic hydrocarbon (alicyclic monocycle).
In this specification, a heteroaryl group is included in an aryl group, and a heteroarylene group is included in an arylene group.

Aromatic rings include aromatic hydrocarbon rings such as benzene, indene, naphthalene, azulene, styrene, toluene, xylene, mesitylene, cumene, anthracene, phenanthrene, triphenylene, benzoanthracene, pyrene, chrysene, fluorene, biphenyl, corannulene, perylene, fluoranthene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[ghi]perylene, coronene, dibenzo[g,p]chrysene, acenaphthylene, acenaphthene, naphthacene, pentacene, and cyclooctatetraene, more typically aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and pyrene; and furan, pyran, pyridine, pyrimidine, pyrazine, thiophene, and pyridine. aromatic heterocycles such as pyrrole, N-alkylpyrrole, N-arylpyrrole, imidazole, pyridine, pyrimidine, pyrazine, triazine, thiazole, indole, phenylindole, bisindolefluorene, bisindolebenzofluorene, bisindoledibenzofluorene, purine, quinoline, isoquinoline, chromene, thianthrene, phenothiazine, phenoxazine, xanthene, acridine, phenazine, carbazole, and indolocarbazole, and more typically, furan, thiophene, pyrrole, indole, phenylindole, bisindolefluorene, phenothiazine, carbazole, and indolocarbazole, but are not limited thereto.

The aromatic ring (eg, benzene ring, naphthalene ring, etc.) may have an arbitrary substituent, and such substituents include, for example, the following atoms and groups.
- a halogen atom - a saturated or unsaturated linear, branched or cyclic hydrocarbon group (-R ^a ) which may be interrupted one or more times by an oxygen atom in the middle of the hydrocarbon chain (including alkyl groups, alkenyl groups, and alkynyl groups (e.g., propargyl groups), and aryl groups, which may be interrupted one or more times by an oxygen atom in the middle of the hydrocarbon chain),
-OR (wherein R represents the hydrocarbon group -R ^a ).
Aryloxy group -NH ₂ , -NHR or -NR ₂ (wherein the two R's may be the same or different), where R represents the above-mentioned hydrocarbon group -R ^a .
- Hydroxyl group - Hydroxyalkyl group - Carboxy group - Formyl group - Cyano group - Nitro group - Ester group (for example, -CO ₂ R or -OCOR, where R represents the hydrocarbon group -R ^a ).
an amide group [for example, -NHCOR, -CONHR, -NRCOR (wherein the two R's may be the same or different), or -CONR ₂ (wherein the two R's may be the same or different), where R represents the hydrocarbon group -R ^a ];
sulfonyl-containing groups (e.g., -SO ₂ R, where R represents the hydrocarbon group -R ^a or a hydroxyl group -OH);
Thiol group (-SH)
A sulfide-containing group (-SR, where R represents the hydrocarbon group -R ^a ).
an organic group containing an ether bond [a residue of an ether compound represented by R ¹¹ -O-R ¹¹ (wherein each R ¹¹ independently represents an alkyl group having 1 to 6 carbon atoms, such as a methyl group or an ethyl group, or an aryl group, such as a phenyl group, a naphthyl group, an anthranyl group or a pyrenyl group); for example, an organic group containing an ether bond, such as a methoxy group, an ethoxy group or a phenoxy group]

"Aromatic ring" also includes organic groups having one or more condensed rings of aromatic rings (such as benzene, naphthalene, anthracene, and pyrene) with one or more aliphatic or heterocyclic rings. Examples of aliphatic rings include cyclobutane, cyclobutene, cyclopentane, cyclopentene, cyclohexane, cyclohexene, methylcyclohexane, methylcyclohexene, cycloheptane, and cycloheptene, and examples of heterocyclic rings include furan, thiophene, pyrrole, imidazole, pyran, pyridine, pyrimidine, pyrazine, pyrrolidine, piperidine, piperazine, and morpholine.

The "aromatic ring" may be an organic group having a structure in which two or more aromatic rings are linked by a divalent linking group. Examples of the divalent linking group include an alkylene group, an arylene group, -NH-, -NHCO-, -O-, -COO-, -CO-, -S-, -SS-, and -SO ₂ -. The divalent linking group may also be a divalent group obtained by removing one hydrogen atom from any of the substituents of the aromatic ring described above.

(I-4) "Heterocycle"
The term "heterocycle" encompasses both aliphatic heterocycles and aromatic heterocycles, and is a concept that encompasses not only monocyclic (heteromonocycles) but also polycyclic (heteropolycycles). In the case of a polycycle, at least one monocycle is a heteromonocycle, but the remaining monocycles may be aromatic hydrocarbon monocycles or alicyclic monocycles. For examples of aromatic heterocycles, see the examples in (I-3) above. As with the aromatic ring in (I-3) above, it may have a substituent.

(I-5) “Non-aromatic ring” (aliphatic ring)
When the "non-aromatic ring" is a monocycle, the "non-aromatic monocycle" refers to a monocyclic hydrocarbon that does not belong to the aromatic group, and is typically a monocycle of an alicyclic compound. It may also be called an aliphatic monocycle (which may include an aliphatic heteromonocycle, and may contain an unsaturated bond as long as it does not belong to the aromatic group). It may have a substituent, as with the aromatic ring of (I-3) above.

Examples of non-aromatic monocyclic rings (aliphatic rings, aliphatic monocyclic rings) include cyclopropane, cyclobutane, cyclobutene, cyclopentane, cyclopentene, cyclohexane, methylcyclohexane, cyclohexene, methylcyclohexene, cycloheptane, cycloheptene, etc.

When the "non-aromatic ring" is polycyclic, the "non-aromatic polycyclic ring" refers to a polycyclic hydrocarbon that does not belong to the aromatic group, and is typically a polycyclic ring of an alicyclic compound. It may also be called an aliphatic polycyclic ring [which may include an aliphatic heteropolycyclic ring (at least one of the monocyclic rings that make up the polycyclic ring is an aliphatic heterocyclic ring), or may contain unsaturated bonds as long as it does not belong to an aromatic compound]. It includes non-aromatic bicyclic rings, non-aromatic tricyclic rings, and non-aromatic tetracyclic rings.

When the "non-aromatic ring" is a bicycle, the "non-aromatic bicycle" refers to a condensed ring composed of two monocyclic hydrocarbons that are not aromatic, typically a condensed ring of two alicyclic compounds. In this specification, it is sometimes referred to as an aliphatic bicycle (which may include an aliphatic heterobicycle, and may contain unsaturated bonds as long as it does not belong to aromatic compounds). Examples of non-aromatic bicycles include bicyclopentane, bicyclooctane, and bicycloheptene.

When the "non-aromatic ring" is a tricycle, the "non-aromatic tricycle" refers to a condensed ring composed of three monocyclic hydrocarbons that are not aromatic, and is typically a condensed ring of three alicyclic compounds (each of which may be a heterocycle or may contain unsaturated bonds as long as it is not an aromatic compound). Examples of non-aromatic tricycles include tricyclooctane, tricyclononane, and tricyclodecane.

When the "non-aromatic ring" is a tetracyclic ring, it refers to a condensed ring composed of four monocyclic hydrocarbons that are not aromatic, and is typically a condensed ring of four alicyclic compounds (each of which may be a heterocyclic ring or may contain unsaturated bonds as long as it is not an aromatic compound). An example of a non-aromatic tetracyclic ring is hexadecahydropyrene.

(I-6)
The term "carbon atoms constituting a ring (moiety)" refers to carbon atoms constituting a hydrocarbon ring (which may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring) in an unsubstituted state.

(I-7)
The term "hydrocarbon group" refers to a group formed by removing one or more hydrogen atoms from a hydrocarbon, and such hydrocarbons include saturated or unsaturated aliphatic hydrocarbons, saturated or unsaturated alicyclic hydrocarbons, and aromatic hydrocarbons.

(I-8)
In the chemical structural formula showing the unit structure of the novolac resin in this specification, a bond (indicated by *) may be shown for convenience. However, unless otherwise specified, such a bond may be located at any available bonding position in the unit structure, and does not in any way limit the bonding position in the unit structure.

The resin (G) has a composite unit structure.
The composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms.

（式（ＡＢ）中、Ａは、単位構造（Ａ）を表し、Ｂは、単位構造（Ｂ）を表す。） The composite unit structure contained in the resin (G) is represented, for example, by the following formula (AB).

(In formula (AB), A represents a unit structure (A), and B represents a unit structure (B).)

<<A-1: Unit structure (A)>>
The unit structure (A) has an aromatic ring.
The unit structure (A) has, for example, at least one of an oxygen atom constituting an aromatic ring, a sulfur atom constituting an aromatic ring, an oxygen atom bonded to an aromatic ring, a nitrogen atom constituting an aromatic ring, and a nitrogen atom directly bonded to an aromatic ring.
The unit structure (A) does not have a heteroatom, for example, as an atom constituting an aromatic ring or an atom bonded to the aromatic ring.

The number of carbon atoms contained in the unit structure (A) is not particularly limited, but is, for example, 4 to 100, and preferably 4 to 50.

Preferably, such aromatic rings have 4 to 30 carbon atoms, more preferably 4 to 24 carbon atoms.

Preferably, such aromatic rings are one or more benzene rings, naphthalene rings, anthracene rings, pyrene rings; or condensed rings of a benzene ring, a naphthalene ring, an anthracene ring, or a pyrene ring with a heterocycle or an aliphatic ring (such as a fluorene ring, a benzofluorene ring, a dibenzofluorene ring, an indole ring, a carbazole ring, or an indolocarbazole ring).

The aromatic ring may have any substituent, but from the viewpoint of polymerization reactivity, the substituent may contain the minimum necessary number of heteroatoms. In addition, two or more aromatic rings may be linked by a linking group, and the linking group may contain the minimum necessary number of heteroatoms. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

The "aromatic ring" may contain at least one heteroatom selected from N, S and O on, within or between the rings.

Examples of the heteroatom which may be contained on the ring include a nitrogen atom contained in an amino group (e.g., a propargylamino group) or a cyano group; an oxygen atom contained in an oxygen-containing substituent such as a formyl group, a hydroxy group, a carboxy group, an alkoxy group, an alkenyloxy group, an alkynyloxy group (e.g., a propargyloxy group), or an aryloxy group; and a nitrogen atom and an oxygen atom contained in a nitro group which is an oxygen-containing substituent and a nitrogen-containing substituent.
Examples of the heteroatom that may be contained in the ring include the oxygen atom contained in furan or xanthene, the nitrogen atom contained in carbazole or pyrrole, and the sulfur atom contained in phenothiazine.
Examples of the heteroatom which may be contained in the linking group of two or more aromatic rings include the nitrogen atom, oxygen atom and sulfur atom contained in -NH-, -NHCO-, -O-, -COO-, -CO-, -S-, -SS- and -SO ₂ -.
In this specification, "atoms constituting an aromatic ring" is synonymous with "atoms contained within a ring". "Atoms bonded to an aromatic ring" refers to, for example, "atoms directly bonded to a ring among atoms or groups contained on the ring" and "atoms directly bonded to a ring among atoms contained between rings".
For example, the atoms that constitute a benzene ring are carbon atoms.
For example, the atoms that constitute a pyrrole ring are a carbon atom and a nitrogen atom.
For example, the oxygen atom of a phenolic hydroxyl group is not an atom that constitutes an aromatic ring.
For example, the oxygen atom of the hydroxyl group of phenol is an atom bonded to a benzene ring, and is an atom of a group contained on the benzene ring that is directly bonded to the benzene ring.

<<A-2: Examples of skeletons constituting unit structure (A)>>
The unit structure (A) has, for example, a skeleton having an aromatic ring.

As a skeleton having an aromatic ring, an aromatic amine skeleton, a nitrogen-containing aromatic heterocyclic skeleton, and a phenol skeleton are preferred.

The unit structure (A) is, for example, a residue in which two hydrogen atoms have been removed from a skeleton having an aromatic ring.
The skeleton having an aromatic ring is derived from, for example, a compound having an aromatic ring when synthesizing the resin (G). The skeleton having an aromatic ring is, for example, a residue obtained by removing two hydrogen atoms from a compound having an aromatic ring when synthesizing the resin (G).

The skeleton having an aromatic ring may have a substituent.
Examples of the substituent include a halo group (halogen atom), an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, a hydroxy group, a hydroxyalkyl group, a carboxy group, a formyl group, a cyano group, a nitro group, an ester group, an amide group, a sulfonyl-containing group, a thiol group, a sulfide-containing group, and an ether bond-containing group.
The alkyl group may be a straight-chain, branched or cyclic alkyl group having 1 to 20 carbon atoms.
The alkenyl group includes linear, branched or cyclic alkenyl groups having 2 to 10 carbon atoms.
The alkynyl group includes linear, branched or cyclic alkynyl groups having 2 to 10 carbon atoms.
Examples of the alkoxy group include a group represented by -OR, where R represents a saturated or unsaturated linear, branched or cyclic hydrocarbon group (-R ^a ) in which the hydrocarbon chain may be interrupted one or more times by an oxygen atom. The number of carbon atoms in the alkoxy group is, for example, 1 to 20.
The aryl group includes an aryl group having 6 to 30 carbon atoms.
The aryloxy group includes an aryloxy group having 6 to 30 carbon atoms.
The amino group may be a group represented by -NH ₂ , -NHR or -NR ₂ , where R represents the hydrocarbon group -R ^a , and in -NR ₂ , the two R's may be the same or different.
The hydroxyalkyl group may be a straight-chain, branched or cyclic hydroxyalkyl group having 1 to 20 carbon atoms.
The ester group includes a group represented by -CO ₂ R or -OCOR, where R represents the above-mentioned hydrocarbon group -R ^a .
The amide group includes groups represented by -NHCOR, -CONHR, -NRCOR or _-CONR2 , where R represents the hydrocarbon group -R ^a , and when there are two R, the two R may be the same or different.
The sulfonyl-containing group includes a group represented by -SO ₂ R, where R represents the above-mentioned hydrocarbon group -R ^a or a hydroxy group -OH.
An example of the sulfide-containing group is a group represented by -SR, where R represents the above-mentioned hydrocarbon group -R ^a .
The ether bond-containing group may be a residue of an ether compound containing an ether bond represented by R ¹¹ -O-R ¹¹ , where each R ¹¹ independently represents an alkyl group having 1 to 6 carbon atoms, such as a methyl group or an ethyl group, or an aryl group, such as a phenyl group, a naphthyl group, an anthranyl group, or a pyrenyl group. The ether bond-containing group may be an organic group containing an ether bond, such as a methoxy group, an ethoxy group, or a phenoxy group.

（式（Ａ－１ａ）～式（Ａ－１ｃ）中、Ａｒ^１１は、それぞれ独立して、芳香族環の残基を表す。Ｒ^１１は、それぞれ独立して、水素原子、又は芳香族環の残基を表す。 <<<A-2-1: Aromatic amine skeleton>>>
The aromatic amine skeleton refers to a skeleton having an aromatic ring and a nitrogen atom that is bonded to the aromatic ring but does not constitute a ring.
Examples of the aromatic amine skeleton include skeletons represented by the following formulas (A-1a) to (A-1c).
As described later, in the unit structure (A), the hydrogen atom of the NH group may be replaced with a substituent. Examples of the substituent include the substituents described in the above (I-3) "Aromatic ring", the substituents described in the above (A-2) "Examples of skeletons constituting the unit structure (A)", and the substituents (S) represented by the formulae (S1) to (S7) described later.

In formulae (A-1a) to (A-1c), Ar ¹¹ each independently represents a residue of an aromatic ring. R ¹¹ each independently represents a hydrogen atom or a residue of an aromatic ring.

Examples of the aromatic ring in the aromatic ring residue of Ar ¹¹ and R ¹¹ include aromatic rings represented by the following formula (G1): These aromatic rings may have a substituent.

Examples of the skeleton represented by formula (A-1a) include the following skeletons. The aromatic rings in these skeletons may have a substituent, and the hydrogen atom of the NH group may be replaced with a substituent. The same applies to the following skeletons.

Examples of the skeleton represented by formula (A-1b) include the following skeletons.

Examples of the skeleton represented by formula (A-1c) include the following skeletons.

（式中、Ａｒ^２１は、それぞれ独立して、芳香族環の残基を表す。
　Ｒ^２１は、それぞれ独立して、水素原子、又は芳香族環の残基を表す。
　Ｒ^２２は、それぞれ独立して、水素原子、炭素原子数１～５の炭化水素基、又は芳香族環の残基を表す。隣接する２つのＲ^２２は、一緒になって不飽和の脂肪族環を形成していてもよい。なお、不飽和の脂肪族環における不飽和結合の一つは、ピロール環を構成する不飽和結合を指す。
　Ｒは、それぞれ独立して、水素原子、芳香族環の残基、又はＬとの結合手を表す。Ｌは、単結合、又は連結基を表す。ｎ１は１を表し、ｎ２は１又は２を表す。式（Ａ－２ｂ－２）及び式（Ａ－２ｃ－４）において、Ｌが単結合の場合、それぞれ、部分構造（Ｉｎ１）と部分構造（Ｉｎ２）とは、及び部分構造（Ｃａ１）と部分構造（Ｃａ２）とは、２つの窒素原子同士が結合することによって結合しているか、２つのＡｒ^２１同士が結合することによって結合しているか、又は窒素原子とＡｒ^２１とが結合することによって結合している。式（Ａ－２ｂ－２）及び式（Ａ－２ｃ－４）において、Ｌが連結基の場合、Ｌは、Ｎ又はＡｒ^２１と結合している。） <<<A-2-2: Nitrogen-containing aromatic heterocyclic skeleton>>>
The nitrogen-containing aromatic heterocyclic skeleton refers to a skeleton having an aromatic heterocyclic ring having a nitrogen atom as an atom constituting the heterocyclic ring.
Examples of the nitrogen-containing aromatic heterocycle include a pyrrole ring, an indole ring, a carbazole ring, a pyridine ring, an acridine ring, a phenoxazine ring, a phenothiazine ring, etc. These nitrogen-containing aromatic heterocycles may have a substituent.
Examples of the nitrogen-containing aromatic heterocyclic skeleton include skeletons represented by the following formula (A-2a), (A-2b-1), (A-2b-2), (A-2c-1), (A-2c-2), (A-2c-3), (A-2c-4), (A-2d), (A-2e), (A-3a), or (A-3b).
As described later, in the unit structure (A), the hydrogen atom of the NH group may be replaced with a substituent. Examples of the substituent include the substituents described in the above (I-3) "Aromatic ring", the substituents described in the above (A-2) "Examples of skeletons constituting the unit structure (A)", and the substituents (S) represented by the formulae (S1) to (S7) described later.

(In the formula, each Ar ²¹ independently represents a residue of an aromatic ring.
Each ^R21 independently represents a hydrogen atom or a residue of an aromatic ring.
Each R ²² independently represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or a residue of an aromatic ring. Two adjacent R ²² may be joined together to form an unsaturated aliphatic ring. One of the unsaturated bonds in the unsaturated aliphatic ring is an unsaturated bond constituting a pyrrole ring.
Each R independently represents a hydrogen atom, a residue of an aromatic ring, or a bond to L. L represents a single bond or a linking group. n1 represents 1, and n2 represents 1 or 2. In formulas (A-2b-2) and (A-2c-4), when L is a single bond, the partial structure (In1) and the partial structure (In2), and the partial structure (Ca1) and the partial structure (Ca2) are bonded by two nitrogen atoms being bonded to each other, or two Ar ²¹ being bonded to each other, or a nitrogen atom being bonded to Ar ^21. In formulas (A-2b-2) and (A-2c-4), when L is a linking group, L is bonded to N or Ar ^21. )

Examples of the aromatic ring in the aromatic ring residue of Ar ²¹ , R ²¹ , R ²² , and R include aromatic rings represented by the following formula (G2): These aromatic rings may have a substituent.

Examples of the unsaturated aliphatic ring formed by two adjacent ^R22s taken together include the following rings: These aliphatic rings may have a substituent.

Examples of the linking group in L include a saturated hydrocarbon group having 1 to 5 carbon atoms and a valence of (n1+n2), and a residue in which (n1+n2) hydrogen atoms have been removed from an aromatic ring.

（式（Ａ－２ｄ）中、
　Ｒ^１１はそれぞれ独立して、水素原子、又は芳香族基を表し、
　Ａｒは芳香族環部分であり、それぞれ独立して、ベンゼン環、２～３個のベンゼン環により構成される縮合環、又は下記式（Ａｒ０１）で表される構造であり、
　Ｘ^０は、単結合、－Ｏ－、－Ｓ－、－ＮＲ^１２－又は－ＣＲ^１３Ｒ^１４－を表し、Ｒ^１２は、Ｒ^１１と同一又は異なってＲ^１１の定義と同一であり、Ｒ^１３及びＲ^１４はそれぞれ、水素原子又は炭素原子数１～６の炭化水素基を表し、
　ｎは１または２であり、
　ｎが１の場合、Ｚは一価の有機基を表し、ｎが２の場合、Ｚは二価の有機基を表す。） <Formula (A-2d)>

(In formula (A-2d),
Each R ¹¹ independently represents a hydrogen atom or an aromatic group;
Ar is an aromatic ring moiety, each independently being a benzene ring, a fused ring constituted by 2 to 3 benzene rings, or a structure represented by the following formula (Ar01):
X ⁰ represents a single bond, -O-, -S-, -NR ¹² - or -CR ¹³ R ¹⁴ -, R ¹² is the same as or different from R ¹¹ and has the same definition as R ¹¹ , R ¹³ and R ¹⁴ each represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms,
n is 1 or 2;
When n is 1, Z represents a monovalent organic group, and when n is 2, Z represents a divalent organic group.

In the unit structure (A), R ¹¹ in formula (A-2d) may be a substituent.
When R ¹¹ is a substituent or an aromatic group, R ¹¹ is, for example,
(i) a methylol group,
(ii) an aryl group having 6 to 30 carbon atoms, or (iii) a linear, branched or cyclic alkoxymethyl group having 2 to 20 carbon atoms; a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; or an alkynyl group having 2 to 10 carbon atoms,
However, with regard to (ii) and (iii), the hydrocarbon chain portion may be further interrupted by an oxygen-containing substituent, a sulfur-containing substituent, a nitrogen-containing substituent, an aryl group or a halo group, or with regard to (iii), the hydrocarbon chain portion may be further interrupted by an oxygen-containing substituent, a sulfur-containing substituent, a nitrogen-containing substituent or an arylene group.

（式（Ａ－２ｄ－１）中のＲ^１１、Ａｒ、及びＸ^０は、それぞれ、式（Ａ－２ｄ）中のＲ^１１、Ａｒ、及びＸ^０と同義である。Ｒ^２１は、炭素原子数６～３０のアリール基、炭素原子数２～１０のアルケニル基、又は炭素原子数２～１０のアルキニル基である。） An example of the skeleton represented by formula (A-2d) is the skeleton represented by the following formula (A-2d-1).

(R ¹¹ , Ar, and X ⁰ in formula (A-2d-1) are respectively defined as R ¹¹ , Ar, and X ⁰ in formula (A-2d). R ²¹ is an aryl group having 6 to 30 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.)

（式（Ａｒ０１）中のＲ^１１ａは、式（Ａ－２ｄ－１）中のＲ^１１と同義であり、Ｒ^２１ａは、式（Ａ－２ｄ－１）中のＲ^２１と同義であり、Ａｒ^ａは、式（Ａ－２ｄ－１）中のＡｒと同義であり、Ｘ^０ａは、式（Ａ－２ｄ－１）中のＸ^０と同義である。
　式（Ａｒ０１）中の２つの炭素原子ａとｂ、ｂとｃ又はｃとｄにおいて、式（Ａ－２ｄ）又は式（Ａ－２ｄ－１）中のＸ^０を含む単環部分と縮合環を形成する。） In the formula (A-2d) and the formula (A-2d-1), Ar is, for example, a benzene ring or a naphthalene ring.
Ar in formula (A-2d) and formula (A-2d-1) may be a structure represented by the following formula (Ar01).

(R ^11a in formula (Ar01) has the same definition as R ¹¹ in formula (A-2d-1), R ^21a has the same definition as R ²¹ in formula (A-2d-1), Ar ^a has the same definition as Ar in formula (A-2d-1), and X ^0a has the same definition as X ⁰ in formula (A-2d-1).
Two carbon atoms a and b, b and c, or c and d in formula (Ar01) form a condensed ring with the monocyclic moiety containing ^X0 in formula (A-2d) or formula (A-2d-1).

Here, the monocyclic moiety containing ^X0 represents a monocyclic ring represented by the following formula (AP011) in formula (A-2d).

（式（Ａ－２ｄ－２）及び式（Ａ－２ｄ－３）中、Ｒ^１１、Ａｒ、及びＸ^０は、それぞれ、式（Ａ－２ｄ）中のＲ^１１、Ａｒ、及びＸ^０と同義である。
　Ｌは、単結合、又は二価の連結基を表し、二価の連結基としては、例えば、－Ｏ－、－Ｓ－、－ＳＯ_２－、－ＣＯ－、－ＣＯＮＨ－、－ＣＯＯ－、－ＮＲ^１０１－、―（ＣＲ^１０２Ｒ^１０３）ｍ^１－、－（Ａｒ^１０１）ｍ^２－、－ＣＨ_２－（Ａｒ^１０１）ｍ^２－ＣＨ_２－、又は－（ｃｙｃｌｏ－Ｒ）－を表す。Ｒ^１０１、Ｒ^１０２、及びＲ^１０３は、それぞれ独立して、水素原子；炭素原子数１～５の炭化水素基；又は炭素原子数６～３０のアリール基を表し；ｍ^１は１～１０の整数を表す。そして、Ａｒ^１０１は、それぞれ独立して、炭素原子数６～３０のアリーレン基を表し；ｍ^２は互いに単結合で結合している芳香族環の数である１～３の整数を表す。「ｃｙｃｌｏ－Ｒ」は、１つ又は２つのベンゼン環又はナフタレン環と縮合環を形成していてもよい、５～８員環、好ましくは６～８員環の二価の脂環式炭化水素基を表す。
　Ｒ^２２は、それぞれ独立して、置換されていてもよい、炭素原子数６～３０のアリーレン基、炭素原子数２～１０のアルケニレン基、又は炭素原子数２～１０のアルキニレン基を表す。） As the skeleton represented by formula (A-2d), a skeleton represented by formula (A-2d-1) above, a skeleton represented by formula (A-2d-2) below, or a skeleton represented by formula (A-2d-3) below is preferable.

In formulae (A-2d-2) and (A-2d-3), R ¹¹ , Ar and X ⁰ have the same definitions as R ¹¹ , Ar and X ⁰ in formula (A-2d), respectively.
L represents a single bond or a divalent linking group, and examples of the divalent linking group include -O-, -S-, -SO ₂ -, -CO-, -CONH-, -COO-, -NR ¹⁰¹ -, -(CR ¹⁰² R ¹⁰³ )m ¹ -, -(Ar ¹⁰¹ )m ² -, -CH ₂ -(Ar ¹⁰¹ )m ² -CH ₂ -, or -(cyclo-R)-. R ¹⁰¹ , R ¹⁰² , and R ¹⁰³ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an aryl group having 6 to 30 carbon atoms; and m ¹ represents an integer of 1 to 10. Each Ar ¹⁰¹ independently represents an arylene group having 6 to 30 carbon atoms, and m ² represents the number of aromatic rings bonded to each other by single bonds, which is an integer of 1 to 3. "cyclo-R" represents a divalent alicyclic hydrocarbon group having a 5- to 8-membered ring, preferably a 6- to 8-membered ring, which may form a condensed ring with one or two benzene rings or naphthalene rings.
R ²² each independently represents an optionally substituted arylene group having 6 to 30 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or an alkynylene group having 2 to 10 carbon atoms.

（式（Ａ－２ｅ）中、Ｌは、各々のアザアリール縮合環を構成する任意の２つの炭素原子間における、単結合、又は二価の連結基を表し、
　Ｒ^１１及びＲ^２１は、それぞれ独立して、水素原子、又は芳香族環の残基を表し、
　Ｒ^１２及びＲ^２２は、それぞれ独立して、置換基を表し、
　ｎ１及びｎ２は、それぞれ独立に、Ｒ^１２及びＲ^２２の置換基の数を表し、０であってもよく、
　Ａｒ^１及びＡｒ^２は、それぞれ独立に、式（Ａ－２ｅ）中のピロール環部分と縮合環を形成している、ベンゼン環又は２～３つのベンゼン環により構成される縮合環である。） <Formula (A-2e)>

In formula (A-2e), L represents a single bond or a divalent linking group between any two carbon atoms constituting each azaaryl fused ring,
R ¹¹ and R ²¹ each independently represent a hydrogen atom or a residue of an aromatic ring;
R ¹² and R ²² each independently represent a substituent;
n1 and n2 each independently represent the number of substituents of R ¹² and R ²² , and may be 0;
Ar ¹ and Ar ² each independently represent a benzene ring or a fused ring composed of 2 to 3 benzene rings, which forms a fused ring with the pyrrole ring moiety in formula (A-2e).

In the unit structure (A), R ¹¹ and R ²¹ in formula (A-2e) may each be a substituent.
When R ¹¹ and R ²¹ are a substituent or a residue of an aromatic group, R ¹¹ and R ²¹ can be, for example,
(i) a methylol group,
(ii) an aryl group having 6 to 30 carbon atoms, or (iii) a linear, branched or cyclic alkoxymethyl group having 2 to 20 carbon atoms; a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; or an alkynyl group having 2 to 10 carbon atoms,
However, with regard to (ii) and (iii), the hydrocarbon chain portion may be further interrupted by an oxygen-containing substituent, a sulfur-containing substituent, a nitrogen-containing substituent, an aryl group or a halo group, or with regard to (iii), the hydrocarbon chain portion may be further interrupted by an oxygen-containing substituent, a sulfur-containing substituent, a nitrogen-containing substituent or an arylene group.

及び

を構成する芳香族炭素原子と結合していてもよいが、アザアリール縮合環中のピロール環部分を構成する炭素原子と結合していることが好ましい。 In formula (A-2e), L is a single bond or a divalent linking group. L may be bonded to any carbon atom constituting each azaaryl fused ring, and may be bonded to any carbon atom constituting each azaaryl fused ring, such as Ar ¹ or Ar ² ,

and

However, it is preferably bonded to a carbon atom constituting the pyrrole ring portion in the azaaryl condensed ring.

Preferred linking groups (L) are selected from the group consisting of -O-, -S-, -SO ₂ -, -CO-, -CONH-, -COO-, -NH-, -(CR ¹⁰² R ¹⁰³ )m ¹ -, -(Ar ¹⁰¹ )m ² -, -CH ₂ -(Ar ¹⁰¹ )m ² -CH ₂ -, and -(cyclo-R)-. R ¹⁰² and R ¹⁰³ each independently represent a hydrogen atom; a hydrocarbon group having 1 to 5 carbon atoms; or an aryl group having 6 to 30 carbon atoms; m ¹ represents an integer of 1 to 10. Ar ¹⁰¹ each represents an arylene group having 6 to 30 carbon atoms; and m ² represents an integer of 1 to 3, which is the number of aromatic rings bonded to each other by single bonds. "Cyclo-R" represents a divalent alicyclic hydrocarbon group having a 5- to 8-membered ring, preferably a 6- to 8-membered ring, which may form a condensed ring with one or two benzene rings or naphthalene rings.

（式中、Ａｒ^３１及びＡｒ^３２は、それぞれ独立して、芳香族環の残基を表すか、又は、それらに結合する炭素原子と一緒になって、芳香族環の残基を表す。Ｘは、－Ｏ、－Ｓ－、－ＮＨ－、－ＣＨ_２－、－ＣＨ_２－ＣＨ_２－、又は－ＣＨ＝ＣＨ－を表す。） <Formula (A-3a) and Formula (A-3b)>

(In the formula, Ar ³¹ and Ar ³² each independently represent a residue of an aromatic ring, or together with the carbon atom bonded thereto represent a residue of an aromatic ring. X represents -O, -S-, -NH-, -CH ₂ -, -CH ₂ -CH ₂ -, or -CH=CH-.)

Examples of the aromatic ring in the aromatic ring residue of Ar ³¹ and Ar ³² include the aromatic ring represented by the above formula (G1).
Examples of the aromatic ring formed by Ar ³¹ and Ar ³² together with the carbon atom to which they are bonded include a fluorene ring, a benzofluorene ring, and a dibenzofluorene ring.

Examples of the skeleton represented by formula (A-2a) include the following skeletons. The aromatic rings in these skeletons may have a substituent, and the hydrogen atom of the NH group may be replaced with a substituent. The same applies to the following skeletons.

Examples of the skeleton represented by formula (A-2b-1) include the following skeletons.

Examples of the skeleton represented by formula (A-2b-2) include the following skeletons.

Examples of the skeleton represented by formula (A-2c-1) include the following skeletons.

Examples of the skeleton represented by formula (A-2c-2) or formula (A-2c-3) include the following skeletons.

Examples of the skeleton represented by formula (A-2c-4) include the following skeletons.

Examples of the skeleton represented by formula (A-2d) include the following skeletons.

Examples of the skeleton represented by formula (A-2e) include the following skeletons.
Note that specific examples of the skeleton represented by formula (A-2d) and specific examples of the skeleton represented by formula (A-2e) may overlap.

Examples of the skeleton represented by formula (A-3a) include the following skeletons.

Examples of the skeleton represented by formula (A-3b) include the following skeletons.

Other examples of the nitrogen-containing aromatic heterocyclic skeleton include the following skeletons.

<<<A-2-3: Phenol skeleton>>>
The phenol skeleton refers to a skeleton having an aromatic ring and a hydroxyl group bonded to the aromatic ring. In this specification, the phenol skeleton refers to an aromatic ring skeleton having a hydroxyl group bonded to the aromatic ring. For example, skeletons having a hydroxyl group bonded to a condensed ring such as naphthalene, anthracene, pyrene, etc. are also included in the phenol skeleton.
The number of hydroxy groups bonded to the aromatic ring of the phenol skeleton is not particularly limited, and may be one or more. When there are more than one hydroxy groups, the number may be 2 to 10 or 2 to 8. When there are more than one hydroxy groups, the hydroxy groups may be bonded to the same aromatic ring (e.g., a benzene ring) or to different aromatic rings.
In the unit structure (A), the hydrogen atom of the hydroxy group bonded to the aromatic ring may be replaced with a substituent. Examples of the substituent include the substituents described in the above (I-3) "Aromatic ring", the substituents described in the above (A-2) "Examples of skeletons constituting the unit structure (A)", and the substituents (S) represented by the formulae (S1) to (S7) described later.

（式中、ｎ１、ｎ２、ｎ４、ｎ５、ｎ６、及びｎ９は、それぞれ独立して、１～４の整数を表す。ｎ３ａ、ｎ３ｂ、ｎ７ａ、ｎ７ｂ、ｎ８ａ、及びｎ８ｂは、それぞれ独立して、０～４の整数を表す。ただし、ｎ３ａ及びｎ３ｂの合計は、１以上であり、ｎ７ａ及びｎ７ｂの合計は、１以上であり、ｎ８ａ及びｎ８ｂの合計は、１以上である。） Examples of the phenol skeleton include skeletons represented by the following formula (A-4). The aromatic ring in these skeletons may have a substituent, and the hydrogen atom of the hydroxy group may be replaced with a substituent. The same applies to the following skeletons.

(In the formula, n1, n2, n4, n5, n6, and n9 each independently represent an integer from 1 to 4; n3a, n3b, n7a, n7b, n8a, and n8b each independently represent an integer from 0 to 4; provided that the sum of n3a and n3b is 1 or more, the sum of n7a and n7b is 1 or more, and the sum of n8a and n8b is 1 or more.)

（式中、Ａｒ^４１は、それぞれ独立して、芳香族環の残基を表す。
　ｋ１及びｋ２は、それぞれ独立して、１又は２の整数を表す。
　Ｘ^１は、－Ｏ－、－ＣＯ－、－Ｓ－、－ＳＯ_２－、又はハロゲン原子で置換されていてもよいアルキレン基を表す。
　ｋ１が１のとき、Ｘ^２１は、単結合、－Ｏ－、－ＣＯ－、－Ｓ－、－ＳＯ_２－、又はハロゲン原子で置換されていてもよいアルキレン基を表す。
　ｋ２が１のとき、Ｘ^２２は、単結合、－Ｏ－、－ＣＯ－、－Ｓ－、－ＳＯ_２－、又はハロゲン原子で置換されていてもよいアルキレン基を表す。
　ｋ１が２のとき、Ｘ^２１は、ハロゲン原子で置換されていてもよい３価の飽和炭化水素基を表す。
　ｋ２が２のとき、Ｘ^２２は、ハロゲン原子で置換されていてもよい３価の飽和炭化水素基を表す。
　Ｙ^１は、３価の飽和炭化水素基を表す。
　Ｙ^２は、４価の飽和炭化水素基を表す。
　ｍ１及びｍ２は、それぞれ独立して、０～３の整数を表す。ただしｍ１及びｍ２の合計は１以上である。
　ｍ３～ｍ５は、それぞれ独立して、０～３の整数を表す。ただしｍ３～ｍ５の合計は１以上である。
　ｍ６～ｍ８は、それぞれ独立して、０～３の整数を表す。ただしｍ６～ｍ８の合計は１以上である。
　ｍ９～ｍ１２は、それぞれ独立して、０～３の整数を表す。ただしｍ９～ｍ１２の合計は１以上である。） Examples of the phenol skeleton include skeletons represented by the following formula (A-5a), (A-5b), (A-5c), or (A-5d).

(In the formula, each Ar ⁴¹ independently represents a residue of an aromatic ring.
k1 and k2 each independently represent an integer of 1 or 2.
X ¹ represents —O—, —CO—, —S—, —SO ₂ — or an alkylene group which may be substituted with a halogen atom.
When k1 is 1, X ²¹ represents a single bond, —O—, —CO—, —S—, —SO ₂ —, or an alkylene group which may be substituted with a halogen atom.
When k2 is 1, X ²² represents a single bond, —O—, —CO—, —S—, —SO ₂ —, or an alkylene group which may be substituted with a halogen atom.
When k1 is 2, X ²¹ represents a trivalent saturated hydrocarbon group which may be substituted with a halogen atom.
When k2 is 2, X ²² represents a trivalent saturated hydrocarbon group which may be substituted with a halogen atom.
^Y1 represents a trivalent saturated hydrocarbon group.
^Y2 represents a tetravalent saturated hydrocarbon group.
m1 and m2 each independently represent an integer of 0 to 3, provided that the sum of m1 and m2 is 1 or more.
m3 to m5 each independently represent an integer of 0 to 3, provided that the total of m3 to m5 is 1 or more.
m6 to m8 each independently represent an integer of 0 to 3, provided that the total of m6 to m8 is 1 or more.
m9 to m12 each independently represent an integer of 0 to 3, provided that the total of m9 to m12 is 1 or more.

Examples of the aromatic ring in the aromatic ring residue of Ar ⁴¹ include aromatic rings represented by the following formula (G3): These aromatic rings may have a substituent.

The number of carbon atoms of the alkylene group which may be substituted with a halogen atom in X ¹ and X ² is, for example, 1 to 20. The structure of the alkylene group may be, for example, linear, branched, cyclic, or a combination of two or more thereof. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The number of carbon atoms in the saturated hydrocarbon group for Y ¹ and Y ² is, for example, 1 to 20. The structure of the saturated hydrocarbon group may be, for example, linear, branched, cyclic, or a combination of two or more thereof.

（式（Ａ－６ａ）、式（Ａ－６ｂ－１）、式（Ａ－６ｂ－２）、式（Ａ－６ｃ）、及び式（Ａ－６ｄ）中、Ａｒ^５１は、それぞれ独立して、芳香族環の残基を表す。ｎ１１は、それぞれ独立して、１～４の整数を表す。ｐは、それぞれ独立して、０又は１を表す。ｐが１のときは、酸素原子がエーテル結合として芳香族環間の橋掛け構造を形成し、ｐが０のときは、芳香族環間の橋掛け構造となるエーテル結合が存在しない。Ｌは、単結合、又は二価の連結基を表す。） Examples of the phenol skeleton include skeletons represented by the following formula (A-6a), (A-6b-1), (A-6b-2), (A-6c), or (A-6d).

(In formulae (A-6a), (A-6b-1), (A-6b-2), (A-6c), and (A-6d), Ar ⁵¹ each independently represents a residue of an aromatic ring. n11 each independently represents an integer of 1 to 4. p each independently represents 0 or 1. When p is 1, the oxygen atom forms a bridging structure between the aromatic rings as an ether bond, and when p is 0, there is no ether bond that forms a bridging structure between the aromatic rings. L represents a single bond or a divalent linking group.)

The aromatic ring in Ar ⁵¹ may, for example, be the aromatic ring represented by the above formula (G1), and a benzene ring or a naphthalene ring is preferable.
Examples of L include divalent groups obtained by removing two hydrogen atoms from the following structures:

For example, each n11 independently represents 1 or 2.

（式（Ａ－７ａ）、式（Ａ－７ｂ）、及び式（Ａ－７ｃ）中、Ａｒ^６１は、それぞれ独立して、芳香族環の残基を表す。ｎ２１は、それぞれ独立して、１～４の整数を表す。） Examples of the phenol skeleton include skeletons represented by the following formula (A-7a), (A-7b), or (A-7c).

(In formulas (A-7a), (A-7b), and (A-7c), Ar ⁶¹ each independently represents a residue of an aromatic ring. n21 each independently represents an integer of 1 to 4.)

Examples of the aromatic ring in Ar ⁶¹ include the aromatic ring represented by the above formula (G1), and a benzene ring or a naphthalene ring is preferable.
For example, each n21 independently represents 1 or 2.

（式（Ａ－８ａ－１）、式（Ａ－８ｂ）、式（Ａ－８ｃ）、式（Ａ－８ｅ）、式（Ａ－８ｆ）、式（Ａ－８ｇ－１）、及び式（Ａ－８ｇ－２）中、ｎ３１は、それぞれ独立して、１～４の整数を表す。
　式（Ａ－８ａ－２）中、ｎ３２及びｎ３３は、それぞれ独立して、０～４の整数を表す。ただし、ｎ３２とｎ３３との合計は、１以上である。
　式（Ａ－８ｄ）中、ｎ３２及びｎ３３は、それぞれ独立して、０～４の整数を表す。ただし、ｎ３２とｎ３３との合計は、１以上である。
　式（Ａ－８ｂ）中、Ｘ^１は、－Ｏ－、又は－ＮＨ－を表す。
　式（Ａ－８ｄ）中、Ｘ^２は、－Ｏ－、－Ｓ－、又は－ＣＨ_２－を表す。
　式（Ａ－８ｅ）中、Ｘ^３は、－Ｓ－、－ＣＨ_２－、又は－ＮＨ－を表す。
　式（Ａ－８ｆ）中、Ｘ^４は、－ＣＯ－、又は－Ｏ－を表し、Ｘ^５は、－ＣＨ_２－、又は－Ｏ－を表す。） Examples of the phenol skeleton include skeletons represented by the following formula (A-8a-1), (A-8a-2), (A-8b), (A-8c), (A-8d), (A-8e), (A-8f), (A-8g-1), or (A-8g-2).

(In formulas (A-8a-1), (A-8b), (A-8c), (A-8e), (A-8f), (A-8g-1), and (A-8g-2), n31 each independently represents an integer of 1 to 4.
In formula (A-8a-2), n32 and n33 each independently represent an integer of 0 to 4, provided that the sum of n32 and n33 is 1 or more.
In formula (A-8d), n32 and n33 each independently represent an integer of 0 to 4, provided that the sum of n32 and n33 is 1 or more.
In formula (A-8b), X ¹ represents —O— or —NH—.
In formula (A-8d), X ² represents —O—, —S—, or —CH ₂ —.
In formula (A-8e), X ³ represents —S—, —CH ₂ —, or —NH—.
In formula (A-8f), X ⁴ represents —CO— or —O—, and X ⁵ represents —CH ₂ — or —O—.

For example, each n31 independently represents 1 or 2.
n32 and n33 each independently represent 0, 1 or 2, for example.

Examples of the skeleton represented by formula (A-4) include the following skeletons. The aromatic rings in these skeletons may have a substituent, and the hydrogen atoms of the hydroxyl groups may be replaced with a substituent. The same applies to the following skeletons.

Examples of the skeleton represented by formula (A-5a) include the following skeletons.

Examples of the skeleton represented by formula (A-5b) include the following skeletons.

Examples of the skeleton represented by formula (A-5c) include the following skeletons.

Examples of the skeleton represented by formula (A-5d) include the following skeletons.

Examples of the skeleton represented by formula (A-6a) include the following skeletons.

Examples of the skeleton represented by formula (A-6b-1) or formula (A-6b-2) include the following skeletons.

Examples of the skeleton represented by formula (A-6c) include the following skeletons.

Examples of the skeleton represented by formula (A-6d) include the following skeletons.

Examples of the skeleton represented by formula (A-7a), formula (A-7b), or formula (A-7c) include the following skeletons.

Examples of the skeleton represented by formula (A-8a-1) or formula (A-8a-2) include the following skeletons.

Examples of the skeleton represented by formula (A-8b) include the following skeletons.

Examples of the skeleton represented by formula (A-8c) include the following skeletons.

Examples of the skeleton represented by formula (A-8d) include the following skeletons.

Examples of the skeleton represented by formula (A-8e) include the following skeletons.

Examples of the skeleton represented by formula (A-8f) include the following skeletons.

Examples of the skeleton represented by formula (A-8g-1) or formula (A-8g-2) include the following skeletons.

Examples of other skeletons of the phenol skeleton include the following skeletons.

In addition, the H of NH in the skeleton having an aromatic ring, the H of a hydroxy group bonded to the aromatic ring in the skeleton having an aromatic ring, and the hydrogen atom bonded to the aromatic ring in the skeleton having an aromatic ring may be replaced with a substituent.
Examples of the substituent include the substituents (S) represented by the following formulae (S1) to (S7).

（式（Ｓ１）～式（Ｓ７）中、
　Ｒ^ｓａは、炭素原子数１～１０の一価の非芳香族炭化水素基を表す。
　Ｒ^ｓｂは、それぞれ独立して、単結合又は炭素原子数１～１０の二価の非芳香族炭化水素基を表す。
　Ｒ^ｓｃは、それぞれ独立して、炭素原子数１～１０の二価の非芳香族炭化水素基を表す。
　Ｒ^ｓｄ _{ａｌｋｙｎｙｌ}は、それぞれ独立して、炭素原子数２～４のアルキニル基を表す。
　Ａｒ^ｓａは、それぞれ独立して、炭素原子数６～２０の一価の芳香族炭化水素基を表す。
　Ａｒ^ｓｂは、それぞれ独立して、炭素原子数６～２０の二価の芳香族炭化水素基を表す。
　Ｘ^ｓａ及びＸ^ｓｂは、それぞれ独立して、水素原子若しくは炭素原子数１～２０の一価の炭化水素基を表すか、又はＸ^ｓａ及びＸ^ｓｂは、ヒドロキシ基に結合する炭素原子と一緒になって、カルボニル基を構成する。
　ｎは、０～５の整数を表す。
　＊は、結合手を表す。）

(In formulas (S1) to (S7),
R ^sa represents a monovalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms.
Each R ^sb independently represents a single bond or a divalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms.
Each R ^sc independently represents a divalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms.
Each R ^sd _alkynyl independently represents an alkynyl group having 2 to 4 carbon atoms.
Each Ar ^sa independently represents a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
Each Ar ^sb independently represents a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
^Xsa and ^Xsb each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or ^Xsa and ^Xsb together with the carbon atom bonded to the hydroxy group form a carbonyl group.
n represents an integer of 0 to 5.
* represents a bond.)

<R ^sa >
Examples of the monovalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms for R ^sa include an alkyl group having 1 to 10 carbon atoms and a monovalent unsaturated hydrocarbon group having 2 to 10 carbon atoms.
The monovalent unsaturated hydrocarbon group having 2 to 10 carbon atoms has one or more carbon-carbon multiple bonds. When the monovalent unsaturated hydrocarbon group having 2 to 10 carbon atoms has two or more carbon-carbon multiple bonds, the two or more carbon-carbon multiple bonds may all be carbon-carbon double bonds, all be carbon-carbon triple bonds, or a mixture of carbon-carbon double bonds and carbon-carbon triple bonds. The two or more carbon-carbon multiple bonds may be or may not be conjugated.

（＊は、結合手を表す。） <R ^sb and R ^sc >
Examples of the divalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms in R ^sb and R ^sc include alkylene groups having 1 to 10 carbon atoms and divalent unsaturated hydrocarbon groups having 2 to 10 carbon atoms.
The divalent unsaturated hydrocarbon group having 2 to 10 carbon atoms has one or more carbon-carbon multiple bonds. When the divalent unsaturated hydrocarbon group having 2 to 10 carbon atoms has two or more carbon-carbon multiple bonds, the two or more carbon-carbon multiple bonds may all be carbon-carbon double bonds, all may be carbon-carbon triple bonds, or may be a mixture of carbon-carbon double bonds and carbon-carbon triple bonds. The two or more carbon-carbon multiple bonds may be conjugated or non-conjugated.
Examples of R ^sb and R ^sc include the following groups.

(* represents a bond.)

<R ^sd _alkynyl >
R ^sd _alkynyl represents an alkynyl group having 2 to 4 carbon atoms. Examples of the alkynyl group having 2 to 4 carbon atoms include an ethynyl group, a 1-propynyl group, and a propargyl group (2-propynyl group).

^＜Arsa＞
The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in Ar ^sa is a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon having 6 to 20 carbon atoms. Examples of aromatic hydrocarbons having 6 to 20 carbon atoms include benzene, naphthalene, anthracene, phenanthrene, perinaphthane, pyrene, fluorene, and biphenyl.

<Ar ^sb >
The divalent aromatic hydrocarbon group having 6 to 20 carbon atoms in Ar ^sb is a residue obtained by removing two hydrogen atoms from an aromatic hydrocarbon having 6 to 20 carbon atoms. Examples of aromatic hydrocarbons having 6 to 20 carbon atoms include benzene, naphthalene, anthracene, phenanthrene, pyrene, fluorene, and biphenyl.

< ^Xsa and ^Xsb >
Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms for ^Xsa and ^Xsb include monovalent non-aromatic hydrocarbon groups having 1 to 10 carbon atoms and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.
Examples of the monovalent non-aromatic hydrocarbon group having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms.
A monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon having 6 to 20 carbon atoms. Examples of aromatic hydrocarbons having 6 to 20 carbon atoms include benzene, naphthalene, anthracene, phenanthrene, perinaphthane, pyrene, fluorene, and biphenyl.

（＊は、結合手を表す。） Examples of the substituent represented by formula (S1) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S2) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S3) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S4) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S5) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S6) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of the substituent represented by formula (S7) include the following groups.

(* represents a bond.)

（＊は、結合手を表す。） Examples of other substituents include the following groups:

(* represents a bond.)

The unit structure (A) is preferably at least one selected from the following. Note that the positions of the two bonds shown in each unit structure described below are shown merely for convenience, and each bond can extend from any possible carbon atom, and the positions are not limited.

(Examples of unit structures composed of aromatic amine skeletons)
The hydrogen atom on N may be replaced with --NH--.

(Examples of unit structures composed of nitrogen-containing aromatic heterocyclic skeletons)

(Example of a unit structure composed of a phenol skeleton)

<B-1: Unit structure (B)>
The unit structure (B) has one or more carbon atoms.
The unit structure (B) is, for example, a unit structure derived from an aldehyde compound or an aldehyde equivalent.
The unit structure (B) is one or more unit structures containing a linking carbon atom that bonds to an aromatic ring in the unit structure (A) [see (I-1) above], and includes, for example, a structure represented by the formula (B1), (B2) or (B3) shown below. The unit structure (B) can link two unit structures (A) together by forming a covalent bond with the unit structure (A).

　式（Ｂ１）中、
　Ｒ、及びＲ’はそれぞれ独立に水素原子、置換基を有していてもよい炭素原子数６～３０の芳香族環、置換基を有していてもよい炭素原子数３～３０の複素環、又は置換基を有していてもよい炭素原子数１０以下の直鎖、分岐若しくは環状のアルキル基を表す。Ｒ及びＲ’は、それらと結合する炭素原子と一緒になって、環構造を有する構造を形成していてもよい。＊は、結合手を表す。 <<B-2: Formula (B1)>>
The unit structure (B) includes, for example, a structure represented by the following formula (B1): The unit structure (B) may be a structure represented by the following formula (B1).

In formula (B1),
R and R' each independently represent a hydrogen atom, an aromatic ring having 6 to 30 carbon atoms which may have a substituent, a heterocycle having 3 to 30 carbon atoms which may have a substituent, or a linear, branched or cyclic alkyl group having 10 or less carbon atoms which may have a substituent. R and R' may form a structure having a ring structure together with the carbon atom to which they are bonded. * represents a bond.

Examples of the substituent include a hydroxy group, a carboxy group, a formyl group, a nitro group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a cyano group, a group in which the H of a hydroxy group is replaced with the above-mentioned substituent (S), a halo group, etc.

Furthermore, the two bonds in formula (B1) can each be covalently bonded to each aromatic ring in the two unit structures (A).

In the definitions of R and R' in formula (B1), for "aromatic ring" and "heterocycle", please refer to (I-3) and (I-4) above.

In the definition of R and R' in formula (B1), examples of "alkyl group" include methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, cyclopentyl group, and 1-methyl-cyclobutyl group. , 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3, Examples include 3-dimethyl-cyclobutyl, 1-n-propyl-cyclopropyl, 2-n-propyl-cyclopropyl, 1-i-propyl-cyclopropyl, 2-i-propyl-cyclopropyl, 1,2,2-trimethyl-cyclopropyl, 1,2,3-trimethyl-cyclopropyl, 2,2,3-trimethyl-cyclopropyl, 1-ethyl-2-methyl-cyclopropyl, 2-ethyl-1-methyl-cyclopropyl, 2-ethyl-2-methyl-cyclopropyl, 2-ethyl-3-methyl-cyclopropyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

Preferably, R and R' are each independently phenyl, naphthalenyl, anthracenyl, phenanthrenyl, naphthacenyl, or pyrenyl.

（式中、Ａｒは、それぞれ独立して、芳香族環の残基を表す。＊で示す炭素原子は、式（Ｂ１）において、Ｒ及びＲ’と結合する炭素原子である。） Examples of the structure having a ring structure formed by R and R' together with the carbon atom to which they are bonded include structures represented by the following formulas.

(In the formula, each Ar independently represents a residue of an aromatic ring. The carbon atom marked with * is the carbon atom bonded to R and R′ in formula (B1).)

The aromatic ring of Ar can be, for example, an aromatic ring represented by formula (G1).

（式（Ｂ－１ａ）及び式（Ｂ－１ｂ）中、Ｒ、及びＲ’は、式（Ｂ１）中のＲ、及びＲ’と、それぞれ、同義である。ただし、Ｒは、水素原子以外である。
　式（Ｂ－１ｂ）において、Ｒ及びＲ’は、それらと結合する炭素原子と一緒になって、環構造を有する構造を形成していてもよい。） The unit structure (B) including the structure represented by formula (B1) is derived from, for example, an aldehyde compound or a ketone compound.
An example of the aldehyde compound is a compound represented by the following formula (B-1a).
An example of the ketone compound is a compound represented by the following formula (B-1b).

In formula (B-1a) and formula (B-1b), R and R′ have the same meanings as R and R′ in formula (B1), respectively, with the proviso that R is other than a hydrogen atom.
In formula (B-1b), R and R′ may form a structure having a ring structure together with the carbon atom to which they are bonded.

For example, when obtaining resin (G), the carbonyl groups in formula (B-1a) and formula (B-1b) are converted to *-C-* in formula (B1).

Some specific examples of unit structure (B) containing the structure represented by formula (B1) are as follows. * basically indicates the bonding site with unit structure (A). Needless to say, the example structure may be included as part of the whole structure.

<<B-3: Formula (B2)>>
The unit structure (B) includes, for example, a structure represented by the following formula (B2): The unit structure (B) may be a structure represented by the following formula (B2).

　式（Ｂ２）中、
　Ｚ^０は置換基を有していてもよい炭素原子数６～３０の芳香族環残基、脂肪族環残基又は、２つの芳香族若しくは脂肪族の環が単結合で連結された有機基を表す。２つの芳香族環若しくは脂肪族環が単結合で連結された有機基としては、ビフェニル、シクロへキシルフェニル、ビシクロへキシル等の二価の残基を挙げることができる。

In formula (B2),
^Z0 represents an aromatic ring residue or an aliphatic ring residue having 6 to 30 carbon atoms which may have a substituent, or an organic group in which two aromatic or aliphatic rings are linked by a single bond. Examples of the organic group in which two aromatic or aliphatic rings are linked by a single bond include divalent residues such as biphenyl, cyclohexylphenyl, and bicyclohexyl.

Examples of the substituent include a hydroxy group, a carboxy group, a formyl group, a nitro group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a cyano group, a group in which the H of a hydroxy group is replaced with the above-mentioned substituent (S), a halo group, etc.

^J1 and ^J2 each independently represent a divalent organic group which may have a direct bond or a substituent. The divalent organic group is preferably a linear or branched alkylene group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, an aryl group (e.g., a phenyl group, a substituted phenyl group, etc.) or a halo group (e.g., fluorine) as a substituent. Examples of linear alkylene groups include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.

The unit structure (B) containing the structure represented by formula (B2) is derived from, for example, a compound having a hydroxyl group or an alkoxy group bonded to a secondary or tertiary carbon atom, a compound having a hydroxyl group, an alkoxy group or a halo group bonded to the α-position carbon atom (such as the benzylic carbon atom) of an alkylaryl group, or a compound having two carbon-carbon double bonds. These compounds are aldehyde equivalents.

（式（Ｂ－２ａ）、式（Ｂ－２ｂ）、及び式（Ｂ－２ｂ）中、Ｊ^１、Ｊ^２、及びＺ^０は、式（Ｂ２）中のＪ^１、Ｊ^２、及びＺ^０と、それぞれ、同義である。
　式（Ｂ－２ａ）中、Ｘ^ａ、及びＸ^ｂは、それぞれ独立して、二級若しくは三級炭素原子に結合する水酸基若しくはアルコキシ基を表す。
　式（Ｂ－２ｂ）中、Ｙ^ａ、及びＹ^ｂは、それぞれ独立して、アルキルアリール基のα位炭素原子（ベンジル位炭素原子など）に結合する水酸基、アルコキシ基若しくはハロ基を表す。
　式（Ｂ－２ｄ）中、ｎは、０～４の整数を表す。） An example of a compound having a hydroxyl group or an alkoxy group bonded to a secondary or tertiary carbon atom is a compound represented by the following formula (B-2a).
Examples of compounds having a hydroxyl group, an alkoxy group, or a halo group bonded to the α-position carbon atom (such as the benzylic carbon atom) of an alkylaryl group include compounds represented by the following formula (B-2b).
Examples of the compound having two carbon-carbon double bonds include compounds represented by the following formula (B-2c) or (B-2d).

In formula (B-2a), formula (B-2b), and formula (B-2b), J ¹ , J ² , and Z ⁰ have the same meanings as J ¹ , J ² , and Z ⁰ in formula (B2), respectively.
In formula (B-2a), X ^a and X ^b each independently represent a hydroxyl group or an alkoxy group bonded to a secondary or tertiary carbon atom.
In formula (B-2b), Y ^a and Y ^b each independently represent a hydroxyl group, an alkoxy group, or a halo group bonded to the α-position carbon atom (eg, the benzylic carbon atom) of an alkylaryl group.
In formula (B-2d), n represents an integer of 0 to 4.

For example, in obtaining resin (G), X ^a -J ¹ in formula (B-2a) is converted to *-J ¹ in formula (B2), and ^{J 2} -X ^b is converted to J ² -* in formula (B2).
For example, in obtaining resin (G), Y ^a -J ¹ in formula (B-2b) is converted to *-J ¹ in formula (B2), and ^{J 2} -Y ^b is converted to J ² -* in formula (B2).

An example of formula (B-2a) is the following compound:

An example of formula (B-2b) is the following compound:

An example of the formula (B-2c) is the following compound:

Some specific examples of unit structures containing the structure represented by formula (B2) are as follows. * indicates the bonding site with unit structure (A). Needless to say, the unit structure may contain the example structure as part of the whole.

　式（Ｂ３）中、
　Ｚは、置換基を有していてもよい、炭素原子数４～２５の単環、又は二環、三環若しくは四環式の縮合環を有する基である。そして、ここにいう炭素原子数は、置換基を除いた単環、又は二環、三環若しくは四環式の縮合環の環骨格を構成する炭素原子のみの数を意味し、前記単環又は縮合環が複素環である場合の複素環を構成するヘテロ原子の数は含めない。 <<B-4: Formula (B3)>>

In formula (B3),
Z is a group having a monocyclic ring or a bicyclic, tricyclic or tetracyclic fused ring having 4 to 25 carbon atoms, which may have a substituent. The number of carbon atoms referred to here means only the number of carbon atoms constituting the ring skeleton of the monocyclic ring or the bicyclic, tricyclic or tetracyclic fused ring excluding the substituent, and does not include the number of heteroatoms constituting the heterocyclic ring when the monocyclic ring or the fused ring is a heterocyclic ring.

The monocycle is a monocycle that does not satisfy the number of pi electrons of 4n+2 (n is an integer of 0 or more) (hereinafter, this may be referred to as a "non-Huckel monocycle"); at least one of the monocycles constituting the two, three, and four rings is a monocycle that does not satisfy the number of pi electrons of 4n+2 (n is an integer of 0 or more), and the remaining monocycles may be either a monocycle that satisfies the number of pi electrons of 4n+2 (n is an integer of 0 or more) or a monocycle that does not satisfy the number of pi electrons of 4n+2 (n is an integer of 0 or more).

The monocyclic ring, or the bicyclic, tricyclic, or tetracyclic fused ring may further form a fused ring with one or more aromatic rings to form a pentacyclic or higher fused ring, and the number of carbon atoms in the pentacyclic or higher fused ring is preferably 40 or less. The number of carbon atoms referred to here means only the number of carbon atoms constituting the ring skeleton of the pentacyclic or higher fused ring excluding substituents, and does not include the number of heteroatoms constituting the heterocyclic ring when the pentacyclic or higher fused ring is a heterocyclic ring.

X and Y are the same or different and represent a -CR ³¹ R ³² - group, in which R ³¹ and R ³² are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms.

x and y represent the numbers X and Y, respectively, and each independently represents 0 or 1.

及び、式（Ｂ３）中の

の少なくともいずれかは、Ｚの前記非ヒュッケル単環を構成するいずれかの炭素原子（「炭素原子Ｚ」と呼ぶ）と結合（ｘ＝１、ｙ＝１の場合）又は炭素原子Ｚから延びている（ｘ＝０、ｙ＝０の場合）。 In formula (B3),

And, in formula (B3),

At least one of the above is bonded to any carbon atom constituting the non-Hückel monocycle of Z (referred to as "carbon atom Z") (when x = 1, y = 1) or extends from the carbon atom Z (when x = 0, y = 0).

は、Ｚの前記非ヒュッケル単環を構成するいずれかの炭素原子（「炭素原子１」と呼ぶ）と結合（ｘ＝１の場合）又は炭素原子１から延びており（ｘ＝０の場合）、 For example, in the formula (B3),

is bonded to any carbon atom (referred to as "carbon atom 1") constituting the non-Huckel monocyclic ring of Z (when x = 1) or extends from carbon atom 1 (when x = 0),

は、Ｚの前記非ヒュッケル単環を構成するいずれかの炭素原子（「炭素原子２」と呼ぶ）と結合（ｙ＝１の場合）又は炭素原子２から延びており（ｙ＝０の場合）、炭素原子１と炭素原子２は同一でも異なっていてもよく、異なっている場合、同一の非ヒュッケル単環に属していてもよいし、異なる非ヒュッケル単環に属していてもよい。 In formula (B3),

is bonded to any carbon atom (referred to as "carbon atom 2") constituting the non-Hückel monocycle of Z (when y = 1) or extends from carbon atom 2 (when y = 0), and carbon atom 1 and carbon atom 2 may be the same or different, and when they are different, they may belong to the same non-Hückel monocycle or different non-Hückel monocycles.

Furthermore, in formula (B3), optionally, linking carbon atoms other than carbon atom 1 and carbon atom 2 may be included.
When Z is a tricyclic or higher fused ring, the permutation relationship between one or two non-Hückel monocycles to which carbon atoms 1 and 2 in formula (B3) belong and the remaining monocycles in the fused ring is arbitrary, and when carbon atom 1 and carbon atom 2 belong to different non-Hückel monocycles (referred to as "non-Hückel monocycle 1" and "non-Hückel monocycle 2", respectively), the permutation relationship between non-Hückel monocycle 1 and non-Hückel monocycle 2 in the fused ring is also arbitrary.
Specific examples of the organic group containing the structure represented by formula (B3) are as follows. The bonding site with the unit structure (A) is not particularly limited. Needless to say, the structure may contain the exemplified structure as a part of the whole.

Note that the examples include those with more than two bonds (*), but these extra bonds can be used for bonding to aromatic rings in other polymer chains, crosslinking, etc., or they can serve as bonds to hydrogen bonds.

及び、式（Ｂ３）中の

の一方のみが、Ｚの前記非ヒュッケル単環を構成するいずれかの炭素原子（「炭素原子Ｚ」と呼ぶ）と結合（ｘ＝１、ｙ＝１の場合）又は炭素原子Ｚから延びている（ｘ＝０、ｙ＝０の場合）場合について説明する。
　この場合の式（Ｂ３）のより具体的な構造として、たとえば、下記式（Ｃ３１）では、結合の手となりうるｐ、ｋ_１及びｋ_２のうち、ｐとｋ_１、又はｐとｋ_２により、式（Ｂ３）で表される単位構造（Ｂ）となりうる。残りの結合の手は、水素原子と結合している。 Hereinafter, in formula (B3),

And, in formula (B3),

is bonded to any of the carbon atoms constituting the non-Hückel monocycle of Z (referred to as "carbon atom Z") (when x = 1, y = 1) or extends from the carbon atom Z (when x = 0, y = 0).
As a more specific structure of formula (B3) in this case, for example, in the following formula (C31), among p, _k1 and _k2 which can be bonds, p and _k1 or p and _k2 can form a unit structure (B) represented by formula (B3), and the remaining bonds are bonded to hydrogen atoms.

　また、下記の式（Ｃ３２）では、結合の手となりうるｐ、ｋ_１、ｋ_２及びｍのうち、ｐとｋ_１、ｐとｋ_２、又はｐとｍにより、式（Ｂ３）で表される単位構造（Ｂ）となりうる。残りの結合の手は、水素原子と結合している。

In addition, in the following formula (C32), among p, _k1 , _k2 , and m which can be bonds, p and _k1 , p and _k2 , or p and m can form a unit structure (B) represented by formula (B3). The remaining bonds are bonded to hydrogen atoms.

　式（Ｃ３１）又は式（Ｃ３２）に該当する式（Ｂ３）のより具体的な種々の例を若干挙げれば、下記のとおりである。＊は単位構造（Ａ）との結合部位を示す。

Some specific examples of formula (B3) corresponding to formula (C31) or formula (C32) are as follows: * indicates the bonding site with the unit structure (A).

　なお、上記具体例において、芳香族環からの結合の手がない場合、ポリマー末端の具体例となりうる。 In formula (B3), the aromatic rings in these structures have bonds extending therefrom to other unit structures (e.g., unit structure (A)), but in the specific examples below, such bonds are omitted. Needless to say, unit structures may contain the exemplified structures as a part of the whole.

In the above specific examples, when there is no bond from the aromatic ring, it can be a specific example of a polymer end.

Novolak resins having a structure represented by formula (AB) can be prepared by known methods. For example, they can be prepared by condensing a ring-containing compound represented by H-A-H with an oxygen-containing compound represented by OHC-B, O=C-B, RO-B-OR, RO-CH ₂ -B-CH ₂ -OR, etc. In the formula, A and B are as defined above. R represents a hydrogen atom, a halogen, or an alkyl group having about 1 to 3 carbon atoms.

The ring-containing compound and the oxygen-containing compound may each be used alone or in combination of two or more. In this condensation reaction, the oxygen-containing compound can be used in a ratio of 0.1 to 10 moles, preferably 0.1 to 2 moles, per mole of the ring-containing compound.

Catalysts that can be used in the condensation reaction include, for example, mineral acids such as sulfuric acid, phosphoric acid, and perchloric acid; organic sulfonic acids such as p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, methanesulfonic acid, and trifluoromethanesulfonic acid; and carboxylic acids such as formic acid and oxalic acid. The amount of catalyst used varies depending on the type of catalyst used, but is usually 0.001 to 10,000 parts by mass, preferably 0.01 to 1,000 parts by mass, and more preferably 0.05 to 100 parts by mass per 100 parts by mass of the ring-containing compound (the total amount if multiple types are used).

The condensation reaction can be carried out without a solvent, but is usually carried out using a solvent. There are no particular limitations on the solvent, so long as it can dissolve the reaction substrate and does not inhibit the reaction. Examples include 1,2-dimethoxyethane, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, tetrahydrofuran, tetrahydropyran, dioxane, 1,2-dichloromethane, 1,2-dichloroethane, toluene, N-methylpyrrolidone, and dimethylformamide. The condensation reaction temperature is usually 40°C to 200°C, preferably 100°C to 180°C. The reaction time varies depending on the reaction temperature, but is usually 5 minutes to 50 hours, preferably 5 minutes to 24 hours.

The weight average molecular weight of the novolac resin according to one embodiment of the present invention is usually 500 to 100,000, preferably 600 to 50,000, 700 to 10,000, or 800 to 8,000.

[Composition for forming resist underlayer film]
The composition for forming a resist underlayer film of the present invention contains the above-mentioned resin (I) and a solvent.
Hereinafter, each component of the composition for forming a resist underlayer film will be described.

The content of the resin (I) in the composition for forming a resist underlayer film is, for example, preferably from 25 to 100 mass %, more preferably from 50 to 100 mass %, and even more preferably from 70 to 100 mass %, based on the mass of the film-forming components.
Here, the film-forming components refer to the components remaining after removing the solvent component from the composition for forming a resist underlayer film.

The content of the resin (G) in the composition for forming a resist underlayer film is, for example, preferably 50 to 100 mass%, more preferably 70 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 100 mass%, relative to the mass of the resin (I).
Here, "the content of resin (G) is 100% by mass relative to the mass of resin (I)" means that resin (I) is equivalent to resin (G).

<Solvent>
The solvent is not particularly limited as long as it can dissolve the resin (I) and other optional components added as necessary.

Solvents include, for example, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, methyl isobutyl carbinol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxypropanediol, ethyl 2-hydroxy ...methyl 3-methylbutanoate, ethyl 3-methoxypropanediol, ethyl 3-hydroxypropanediol, ethyl 3-hydroxypropanediol, ethyl 3-hydroxypropanediol, ethyl 3-hydroxypropanediol, ethyl 3-hydroxypropanediol, ethyl 3-hydroxypropanediol Methyl pionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol mono Methyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl acetate, ethyl acetate, amyl acetate, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, ethyl hydroxyacetate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, 3- Examples of the solvent include methyl methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methoxypropyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, 4-methyl-2-pentanol, and γ-butyrolactone. These solvents can be used alone or in combination of two or more.

Also, solvents with a boiling point of 160°C or higher can be included in combination with solvents with a boiling point of less than 160°C.

As such a high boiling point solvent, for example, the following compounds described in WO 2018/131562 (A1) can be preferably used.

［式（ｉ）中のＲ^１、Ｒ^２及びＲ^３は各々水素原子、酸素原子、硫黄原子又はアミド結合で中断されていてもよい炭素原子数１～２０のアルキル基を表し、互いに同一であっても異なっても良く、互いに結合して環構造を形成しても良い。］
　あるいは、特開２０２１－８４９７４号記載の、１，６－ジアセトキシヘキサン（沸点２６０℃）、トリプロピレングリコールモノメチルエーテル（沸点２４２℃）、その他、当該公開公報の段落００８２に記載の種々の高沸点溶媒を好ましく用いることができる。

[In formula (i), R ¹ , R ² and R ³ each represent a hydrogen atom, an oxygen atom, a sulfur atom or an alkyl group having 1 to 20 carbon atoms which may be interrupted by an amide bond, and may be the same or different from each other, and may be bonded to each other to form a ring structure.]
Alternatively, 1,6-diacetoxyhexane (boiling point 260 ° C.), tripropylene glycol monomethyl ether (boiling point 242 ° C.), and various other high boiling point solvents described in paragraph 0082 of JP-A-2021-84974 can be preferably used.

Alternatively, dipropylene glycol monomethyl ether acetate (boiling point 213°C), diethylene glycol monoethyl ether acetate (boiling point 217°C), diethylene glycol monobutyl ether acetate (boiling point 247°C), dipropylene glycol dimethyl ether (boiling point 171°C), dipropylene glycol monomethyl ether (boiling point 187°C), dipropylene glycol monobutyl ether (boiling point 231°C), tripropylene glycol monomethyl ether (boiling point 231°C), tripropylene glycol monomethyl ether (boiling point 231°C), tripropylene glycol monoethyl ... Preferred examples of high-boiling point solvents that can be used include dimethyl ether (boiling point 242°C), gamma-butyrolactone (boiling point 204°C), benzyl alcohol (boiling point 205°C), propylene carbonate (boiling point 242°C), tetraethylene glycol dimethyl ether (boiling point 275°C), 1,6-diacetoxyhexane (boiling point 260°C), dipropylene glycol (boiling point 230°C), 1,3-butylene glycol diacetate (boiling point 232°C), and the various other high-boiling point solvents described in paragraphs 0023 to 0031 of the publication.

The composition for forming a resist underlayer film, which is one aspect of the present invention, may contain an acid and/or a salt thereof and/or an acid generator.

Examples of acids include p-toluenesulfonic acid, trifluoromethanesulfonic acid, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid.

As the salt, a salt of the above-mentioned acid can also be used. As the salt, although it is not limited, ammonia derivative salts such as trimethylamine salts and triethylamine salts, pyridine derivative salts, morpholine derivative salts, etc. can be suitably used.

A single type of acid and/or its salt may be used, or two or more types may be used in combination. The amount of the acid and/or its salt is usually 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.01 to 5% by mass, based on the total solid content.

Acid generators include thermal acid generators and photoacid generators.

Thermal acid generators include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, K-PURE [registered trademark] CXC-1612, CXC-1614, TAG-2172, TAG-2179, TAG-2678, TAG2689, and TAG2700 (manufactured by King Industries), as well as SI-45, SI-60, SI-80, SI-100, SI-110, and SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd.), and other organic sulfonic acid alkyl esters.

Photoacid generators produce acid when the resist is exposed to light. This allows the acidity of the underlayer film to be adjusted. This is one way to match the acidity of the underlayer film to that of the upper layer resist. Adjusting the acidity of the underlayer film also allows the pattern shape of the resist formed in the upper layer to be adjusted.

The photoacid generator contained in the resist underlayer film forming composition of the present invention includes an onium salt compound, a sulfonimide compound, a disulfonyldiazomethane compound, and the like.

Examples of onium salt compounds include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoronormal butanesulfonate, diphenyliodonium perfluoronormal octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoronormal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

Examples of sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

Examples of disulfonyldiazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

A single acid generator may be used, or two or more may be used in combination.

When an acid generator is used, the proportion is 0.01 to 10 parts by mass, or 0.1 to 8 parts by mass, or 0.5 to 5 parts by mass, per 100 parts by mass of the solid content of the composition for forming the resist underlayer film.

The composition for forming a resist underlayer film, which is one aspect of the present invention, may contain, in addition to the above, a crosslinking agent, a surfactant, a light absorbing agent, a rheology adjuster, an adhesive auxiliary, etc., as necessary.

Typical crosslinking agents include aminoplast crosslinking agents and phenoplast crosslinking agents.

As the crosslinking agent, a crosslinking agent having high heat resistance can be used. As a crosslinking agent having high heat resistance, a compound containing a crosslinking-forming substituent having an aromatic ring (e.g., a benzene ring, a naphthalene ring) in the molecule can be preferably used.

Aminoplast crosslinkers include highly alkylated, alkoxylated, or alkoxyalkylated melamine, benzoguanamine, glycoluril, urea, and polymers thereof. Preferred are crosslinkers having at least two crosslink-forming substituents, such as methoxymethylated glycoluril, butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, methoxymethylated thiourea, or methoxymethylated thiourea. Condensates of these compounds can also be used.

Preferably, it is at least one selected from the group consisting of tetramethoxymethylglycoluril and hexamethoxymethylmelamine.

Some concrete examples are as follows:

Phenoplast crosslinking agents include highly alkylated, alkoxylated, or alkoxyalkylated aromatics, their polymers, and the like. Preferred are crosslinking agents having at least two crosslink-forming substituents in one molecule, such as 2,6-dihydroxymethyl-4-methylphenol, 2,4-dihydroxymethyl-6-methylphenol, bis(2-hydroxy-3-hydroxymethyl-5-methylphenyl)methane, bis(4-hydroxy-3-hydroxymethyl-5-methylphenyl)methane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane, bis(3-formyl-4-hydroxyphenyl)methane, bis(4-hydroxy-2,5-dimethylphenyl)formylmethane, and α,α-bis(4-hydroxy-2,5-dimethylphenyl)-4-formyltoluene. Condensates of these compounds can also be used.

In addition to the above, other examples of such compounds include compounds having a partial structure of the following formula (4) and polymers or oligomers having a repeating unit of the following formula (5).

　上記Ｒ^１１、Ｒ^１２、Ｒ^１３、及びＲ^１４は水素原子又は炭素原子数１～１０のアルキル基であり、これらのアルキル基は上述の例示を用いることができる。ｎ１は１～４の整数であり、ｎ２は１～（５－ｎ１）の整数であり、（ｎ１＋ｎ２）は２～５の整数を示す。ｎ３は１～４の整数であり、ｎ４は０～（４－ｎ３）であり、（ｎ３＋ｎ４）は１～４の整数を示す。オリゴマー及びポリマーは繰り返し単位構造の数が２～１００、又は２～５０の範囲で用いることができる。

The above R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are hydrogen atoms or alkyl groups having 1 to 10 carbon atoms, and the above-mentioned examples of these alkyl groups can be used. n1 is an integer of 1 to 4, n2 is an integer of 1 to (5-n1), and (n1+n2) is an integer of 2 to 5. n3 is an integer of 1 to 4, n4 is an integer of 0 to (4-n3), and (n3+n4) is an integer of 1 to 4. The number of repeating unit structures of the oligomers and polymers that can be used is in the range of 2 to 100, or 2 to 50.

Some concrete examples are as follows:

Crosslinking agents such as aminoplast crosslinking agents and phenoplast crosslinking agents may be used alone or in combination of two or more types. The aminoplast crosslinking agent may be produced by a method known per se or a method equivalent thereto, and a commercially available product may also be used.

The amount of the crosslinking agent, such as an aminoplast crosslinking agent or a phenoplast crosslinking agent, used varies depending on the coating solvent used, the base substrate used, the required solution viscosity, the required film shape, etc., but is 0.001 mass% or more, 0.01 mass% or more, 0.05 mass% or more, 0.5 mass% or more, or 1.0 mass% or more relative to the total solid content of the composition for forming a resist underlayer film according to the present invention, and is 80 mass% or less, 50 mass% or less, 40 mass% or less, 20 mass% or less, or 10 mass% or less.

The resist underlayer film forming composition of the present invention does not cause pinholes or striations, and a surfactant can be added to further improve the coatability against surface irregularities.

Examples of the surfactant include nonionic surfactants such as polyoxyethylene alkyl ethers, such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylaryl ethers, such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether; polyoxyethylene-polyoxypropylene block copolymers; sorbitan fatty acid esters, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate; and polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate.
fluorosurfactants such as EFTOP EF301, EF303, EF352 (trade names, manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, R-30, R-40 (trade names, manufactured by Dainippon Ink Co., Ltd.), Fluorad FC430, FC431 (trade names, manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (trade names, manufactured by Asahi Glass Co., Ltd.);
Organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The amount of these surfactants is usually 2.0% by mass or less, and preferably 1.0% by mass or less, based on the total solid content of the composition for forming a resist underlayer film according to the present invention. These surfactants may be added alone or in combination of two or more kinds.

The light absorbing agent may be, for example, a commercially available light absorbing agent described in "Technology and Market of Industrial Dyes" (CMC Publishing) or "Dye Handbook" (edited by the Society of Organic Synthetic Chemistry), such as C.I. Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114, and 124; C.I. Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72, and 73; C.I. C.I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199 and 210; C.I. Disperse Violet 43; C.I. Disperse Blue 96; C.I. Fluorescent Brightening Agent 112, 135 and 163; C.I. Solvent Orange 2 and 45; C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27 and 49; C.I. Pigment Green 10; C.I. Pigment Brown 2, etc. can be suitably used. The above-mentioned light absorbing agent is usually blended in a ratio of 10% by mass or less, preferably 5% by mass or less, based on the total solid content of the composition for forming a resist underlayer film according to the present invention.

Rheology control agents are added mainly to improve the fluidity of the resist underlayer film forming composition, and to improve the film thickness uniformity of the resist underlayer film and the filling ability of the resist underlayer film forming composition into the inside of the hole, particularly in the baking process. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives such as di-n-butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyl decyl adipate; maleic acid derivatives such as di(n-butyl) maleate, diethyl maleate, and dinonyl maleate; oleic acid derivatives such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate; and stearic acid derivatives such as n-butyl stearate and glyceryl stearate. These rheology control agents are usually blended in a ratio of less than 30% by mass based on the total solid content of the resist underlayer film forming composition according to the present invention.

Adhesion aids are added mainly for the purpose of improving the adhesion between the substrate or resist and the composition for forming the resist underlayer film, and in particular to prevent the resist from peeling off during development. Specific examples include chlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane; silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylimidazole; vinyltrichlorosilane; Examples of the adhesive auxiliary include silanes such as silane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane; heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, and mercaptopyrimidine; and ureas such as 1,1-dimethylurea and 1,3-dimethylurea, or thiourea compounds. These adhesive auxiliary agents are usually blended in an amount of less than 5% by mass, preferably less than 2% by mass, based on the total solid content of the composition for forming a resist underlayer film according to the present invention.

The solid content of the resist underlayer film forming composition according to the present invention is 0.1 to 70% by mass, or 0.1 to 60% by mass. The solid content is the content of all components excluding the solvent from the resist underlayer film forming composition. The solid content may contain a crosslinkable resin in a ratio of 1 to 99.9% by mass, or 50 to 99.9% by mass, or 50 to 95% by mass, or 50 to 90% by mass.

[Method of manufacturing plasma-treated resist underlayer film]
The plasma-treated resist underlayer film can be formed, for example, as follows using the composition for forming a resist underlayer film according to the present invention.

A resist underlayer film forming composition according to one embodiment of the present invention is applied onto a substrate (e.g., a silicon wafer substrate, a silicon dioxide-coated substrate ( _SiO2 substrate), a silicon nitride substrate (SiN substrate), a silicon oxynitride substrate (SiON substrate), a titanium nitride substrate (TiN substrate), a tungsten substrate (W substrate), a glass substrate, an ITO substrate, a polyimide substrate, and a substrate coated with a low dielectric constant material (low-k material), etc.) used in the manufacture of a semiconductor device by a suitable application method such as a spinner or coater, and then baked using a heating means such as a hot plate to form a resist underlayer film. The baking conditions are appropriately selected from a baking temperature of 80°C to 800°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150°C to 500°C and the baking time is 0.5 to 2 minutes. Air may be used as the atmospheric gas during baking, and an inert gas such as nitrogen or argon may also be used. In one embodiment, it is particularly preferable that the oxygen concentration is 1% or less. Here, the thickness of the underlayer film formed is, for example, 1 to 10,000 nm, or 1 to 1,000 nm, or 5 to 1,000 nm, or 10 to 500 nm, or 20 to 400 nm, or 30 to 300 nm. Furthermore, if a quartz substrate is used as the substrate, a replica of the quartz imprint mold (mold replica) can be produced.

The plasma treatment conditions are, for example, a source power of preferably 0 to 20,000 W, more preferably 1 to 20,000 W, and even more preferably 1 to 5,000 W. A bias voltage of preferably 0 to 20,000 V, more preferably 1 to 20,000 V, and even more preferably 1 to 5,000 V. A pressure of preferably 0 to 20,000 mTorr, and more preferably 0 to 10,000 mTorr. A gas supply flow rate of preferably 1 to 5,000 sccm. A temperature of preferably -100 to 600°C, and more preferably -10 to 300°C. A time of preferably 1 to 1,200 seconds.

The formed resist underlayer film is subjected to plasma treatment to obtain a plasma-treated resist underlayer film, which is one aspect of the present invention. The plasma-treated resist underlayer film has film properties that change from the underlayer film before treatment because it has been subjected to plasma treatment. The plasma treatment can improve, for example, the etching resistance and optical constants of the resist underlayer film, and can increase the film hardness and film density. Here, examples of the optical constants include a refractive index (n value) and an optical absorption coefficient (k value).
Here, the film thickness of the plasma-treated underlayer film is, for example, 1 to 10,000 nm, or 1 to 1,000 nm, or 5 to 1,000 nm, or 10 to 500 nm, or 20 to 400 nm, or 30 to 300 nm.
The range in which the film properties such as etching resistance are changed by the plasma treatment can be, for example, the surface of the underlayer film, or from the surface to 1 nm, or from the surface to 5 nm, or from the surface to 20 nm, or from the surface to the bottom, based on the film after the plasma treatment. The film properties of the underlayer film can be changed continuously in the film thickness direction.

The plasma-treated resist underlayer film preferably has an intensity ratio Ig/Id of G band to D band as measured by Raman spectroscopy of 0.1 to 10.0, more preferably 0.1 to 5.0, further preferably 0.1 to 3.0, and particularly preferably 0.1 to 1.0.
The Raman spectroscopic analysis is carried out, for example, by the method described in the Examples.

By subjecting the plasma-treated resist underlayer film to plasma treatment, the intensity ratio Ig/Id of the G band to the D band as determined by Raman spectroscopy increases.
The intensity ratio Ig/Id of the plasma-treated resist underlayer film after plasma treatment is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more, relative to the intensity ratio Ig/Id of the resist underlayer film before plasma treatment (hereinafter also referred to as "pre-plasma-treated resist underlayer film"). The upper limit of the intensity ratio Ig/Id of the plasma-treated resist underlayer film relative to the intensity ratio Ig/Id of the resist underlayer film before plasma treatment is not particularly limited, and is, for example, 5.0 times.

It is preferable that the plasma-treated resist underlayer film has an increased peak area of the absorption peak of the carbon-carbon double bond as measured by infrared spectroscopy due to the plasma treatment.
The peak area of the absorption peak of the carbon-carbon double bond of the plasma-treated resist underlayer film after the plasma treatment, as measured by infrared spectroscopy, relative to the peak area of the absorption peak of the carbon-carbon double bond of the pre-plasma-treated resist underlayer film before the plasma treatment (hereinafter also referred to as the "peak area ratio") is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more. The upper limit of the peak area ratio is not particularly limited, and is, for example, 5.0 times.
The peak area of the absorption peak of the carbon-carbon double bond by infrared spectroscopy can be determined, for example, by using a measuring device described in the Examples.

The film density of the plasma-treated resist underlayer film at room temperature (eg, 25° C.) is preferably 1.0 to 2.5 g/cm ³ , more preferably 1.0 to 2.0 g/cm ³ , and even more preferably 1.0 to 1.75 g/cm ³ .
The film density of the plasma-treated resist underlayer film can be determined, for example, by using the measuring device described in the Examples.

The plasma-treated resist underlayer film has its film density increased by the plasma treatment.
The film density of the plasma-treated resist underlayer film relative to the film density of the resist underlayer film before plasma treatment is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more. The upper limit of the film density of the plasma-treated resist underlayer film relative to the film density of the resist underlayer film before plasma treatment is not particularly limited, but is, for example, 5.0 times.

The refractive index of the plasma-treated resist underlayer film at a wavelength of 193 nm is preferably from 1.3 to 2.5, more preferably from 1.4 to 2.0, and even more preferably from 1.5 to 1.9.
The refractive index of the plasma-treated resist underlayer film at a wavelength of 633 nm is preferably from 1.5 to 3.5, more preferably from 1.6 to 3.0, and even more preferably from 1.7 to 2.5.
The refractive index of the plasma-treated resist underlayer film at a wavelength of 193 nm or 633 nm can be determined, for example, by using a measuring device described in the Examples.

The optical absorption coefficient of the plasma-treated resist underlayer film at a wavelength of 193 nm is preferably 0.2 to 1.0, more preferably 0.3 to 0.9, and even more preferably 0.35 to 0.8.
The optical absorption coefficient of the plasma-treated resist underlayer film at a wavelength of 633 nm is preferably 0 to 0.2, and more preferably 0.01 to 0.15.
The optical absorption coefficient of the plasma-treated resist underlayer film at a wavelength of 193 nm or 633 nm can be determined, for example, by using the measuring device described in the Examples.

The refractive index of the plasma-treated resist underlayer film at a wavelength of 193 nm is increased by the plasma treatment.
The refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 193 nm is preferably 1.01 times or more, more preferably 1.03 times or more, and even more preferably 1.05 times or more, relative to the refractive index of the resist underlayer film before the plasma treatment at a wavelength of 193 nm. The upper limit of the refractive index of the plasma-treated resist underlayer film relative to the refractive index of the resist underlayer film before the plasma treatment at a wavelength of 193 nm is not particularly limited, and is, for example, 5.0 times.
The refractive index of the plasma-treated resist underlayer film at a wavelength of 633 nm is increased by the plasma treatment.
The refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 633 nm is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more, relative to the refractive index of the resist underlayer film before the plasma treatment at a wavelength of 633 nm. The upper limit of the refractive index of the plasma-treated resist underlayer film relative to the refractive index of the resist underlayer film before the plasma treatment at a wavelength of 633 nm is not particularly limited, and is, for example, 5.0 times.

By subjecting the plasma-treated resist underlayer film to the plasma treatment, the optical absorption coefficient at a wavelength of 193 nm is reduced.
The optical absorption coefficient of the plasma-treated resist underlayer film at a wavelength of 193 nm after the plasma treatment is preferably 0.99 times or less, more preferably 0.95 times or less, and even more preferably 0.85 times or less, relative to the optical absorption coefficient of the pre-plasma-treated resist underlayer film at a wavelength of 193 nm before the plasma treatment. The lower limit of the optical absorption coefficient of the plasma-treated resist underlayer film at a wavelength of 193 nm relative to the optical absorption coefficient of the pre-plasma-treated resist underlayer film is not particularly limited, and is, for example, 0.2 times.

Also, an adhesion layer and/or a silicon-containing layer containing 99% by mass or less, or 50% by mass or less of Si can be formed by coating or vapor deposition on the plasma-treated resist underlayer film, which is one aspect of the present invention. For example, in addition to the adhesion layer described in JP 2013-202982 A and JP 5827180 A, and the method of forming a silicon-containing resist underlayer film (inorganic resist underlayer film) forming composition described in WO 2009/104552 (A1) by spin coating, a Si-based inorganic material film can be formed by a CVD method or the like.

In addition, by applying the composition for forming a resist underlayer film, which is one aspect of the present invention, onto a semiconductor substrate having a portion with a step and a portion without a step (a so-called stepped substrate) and baking it, the step between the portion with the step and the portion without the step can be reduced.

A method for producing a plasma-treated resist underlayer film according to one embodiment of the present invention includes the steps of:
forming a coating film on a semiconductor substrate using a composition for forming a resist underlayer film according to one embodiment of the present invention;
and forming a plasma-treated resist underlayer film in which, by plasma treating the coating film, the intensity ratio Ig/Id of G band to D band as determined by Raman spectroscopy increases, the peak area of the absorption peak of a carbon-carbon double bond as determined by infrared spectroscopy increases, the refractive index at a wavelength of 193 nm or 633 nm increases, or the optical absorption coefficient at a wavelength of 193 nm decreases.

The plasma treatment conditions may be the same as those described in the examples.

The plasma-treated resist underlayer film has its film hardness increased by the plasma treatment.
The hardness of the plasma-treated resist underlayer film relative to the hardness of the resist underlayer film before plasma treatment is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more. The upper limit of the hardness of the plasma-treated resist underlayer film relative to the hardness of the resist underlayer film before plasma treatment is not particularly limited, and is, for example, 5.0 times.
The hardness of the resist underlayer film before plasma treatment and the hardness of the resist underlayer film after plasma treatment can be measured, for example, by using the measuring device described in the Examples.

The elastic modulus of the plasma-treated resist underlayer film at room temperature (eg, 25° C.) is preferably 50 GPa, more preferably 50 to 400 GPa, further preferably 55 to 300 GPa, and particularly preferably 60 to 250 GPa.
The elastic modulus of the plasma-treated resist underlayer film can be determined, for example, by using the measuring device described in the Examples.

The elastic modulus of the plasma-treated resist underlayer film is improved by subjecting it to the plasma treatment.
The elastic modulus of the plasma-treated resist underlayer film relative to the elastic modulus of the resist underlayer film before plasma treatment is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more. The upper limit of the elastic modulus of the plasma-treated resist underlayer film relative to the elastic modulus of the resist underlayer film before plasma treatment is not particularly limited, and is, for example, 5.0 times.

By subjecting the plasma-treated resist underlayer film to the plasma treatment, the etching resistance is improved.
The etching resistance of the plasma-treated resist underlayer film relative to the etching resistance of the resist underlayer film before plasma treatment is preferably 1.01 times or more, more preferably 1.05 times or more, and even more preferably 1.10 times or more. The upper limit of the etching resistance of the plasma-treated resist underlayer film relative to the etching resistance of the resist underlayer film before plasma treatment is not particularly limited, and is, for example, 5.0 times.
The etching resistance of the resist underlayer film before plasma treatment and the etching resistance of the resist underlayer film after plasma treatment can be determined, for example, by the method described in the Examples.

The gas used in the plasma treatment preferably contains at least a rare gas, nitrogen, and hydrogen. Examples of rare gases include helium, neon, and argon.

The method for producing a plasma-treated resist underlayer film, which is one aspect of the present invention, preferably further includes a step of baking the semiconductor substrate on which the plasma-treated resist underlayer film has been formed at 400°C or higher after the plasma treatment.

[Method of Manufacturing Semiconductor Device]
(i)
A method for manufacturing a semiconductor device according to one aspect of the present invention includes the steps of:
A step of forming a resist underlayer film on a semiconductor substrate using a composition for forming a resist underlayer film according to one embodiment of the present invention;
forming a plasma-treated resist underlayer film by plasma treating the resist underlayer film;
forming a resist film on the plasma-treated resist underlayer film;
A step of forming a resist pattern by irradiating the resist film with light or an electron beam and developing it;
Etching the plasma-treated resist underlayer film through a resist pattern to form a patterned plasma-treated resist underlayer film;
and processing a semiconductor substrate through the patterned plasma-treated resist underlayer film.

(ii)
A method for manufacturing a semiconductor device according to one aspect of the present invention includes the steps of:
A step of forming a resist underlayer film on a semiconductor substrate using a composition for forming a resist underlayer film according to one embodiment of the present invention;
forming a plasma-treated resist underlayer film by plasma treating the resist underlayer film;
forming a hard mask on the plasma-treated resist underlayer film;
Further, a step of forming a resist film on the hard mask;
A step of forming a resist pattern by irradiating the resist film with light or an electron beam and developing it;
Etching the hard mask through the resist pattern to form a patterned hard mask;
Etching the plasma-treated resist underlayer film through a patterned hard mask to form a patterned plasma-treated resist underlayer film; and processing a semiconductor substrate through the patterned plasma-treated resist underlayer film.

(iii)
A method for manufacturing a semiconductor device according to one aspect of the present invention includes the steps of:
A step of forming a resist underlayer film on a semiconductor substrate using a composition for forming a resist underlayer film according to one embodiment of the present invention;
forming a plasma-treated resist underlayer film by plasma treating the resist underlayer film;
forming a hard mask on the plasma-treated resist underlayer film;
Further, a step of forming a resist film on the hard mask;
A step of forming a resist pattern by irradiating the resist film with light or an electron beam and developing it;
Etching the hard mask through the resist pattern to form a patterned hard mask;
Etching the plasma-treated resist underlayer film through a patterned hard mask to form a patterned plasma-treated resist underlayer film;
removing the hard mask; and processing the semiconductor substrate through the patterned plasma-treated resist underlayer film.

(iv)
A method for manufacturing a semiconductor device according to one aspect of the present invention includes the steps of:
A step of forming a resist underlayer film on a semiconductor substrate using a composition for forming a resist underlayer film according to one embodiment of the present invention;
forming a plasma-treated resist underlayer film by plasma treating the resist underlayer film;
forming a hard mask on the plasma-treated resist underlayer film;
Further, a step of forming a resist film on the hard mask;
A step of forming a resist pattern by irradiating the resist film with light or an electron beam and developing it;
Etching the hard mask through the resist pattern to form a patterned hard mask;
Etching the plasma-treated resist underlayer film through a patterned hard mask to form a patterned plasma-treated resist underlayer film;
removing the hard mask;
forming a vapor-deposited film (spacer) on the plasma-treated resist underlayer film after removing the hard mask;
A process of processing the vapor-deposited film (spacer) by etching;
The method includes the steps of: removing the patterned plasma-treated resist underlayer film to leave a patterned deposited film (spacer); and processing a semiconductor substrate through the patterned deposited film (spacer).

The manufacturing methods (i) to (iv) above can be used to process semiconductor substrates.

The process of forming a resist underlayer film using the composition for forming a resist underlayer film, which is one aspect of the present invention, is as described above in [Resist underlayer film].

A hard mask such as a silicon-containing film may be formed as a second resist underlayer film on the resist underlayer film formed by the above process, and a resist pattern may be formed thereon [above (ii) to (iv)].

The hard mask may be a coating film of an inorganic material or the like, or a vapor-deposited film of an inorganic material or the like formed by a vapor deposition method such as CVD or PVD, and examples of the hard mask include a SiON film, a SiN film, and a SiO ₂ film.

Furthermore, an anti-reflective coating (BARC) may be formed on this hard mask, or a resist shape correction film that does not have anti-reflective properties may be formed.

In the process of forming the resist pattern, exposure is performed through a mask (reticle) for forming a predetermined pattern, or by direct writing. For example, g-line, i-line, KrF excimer laser, ArF excimer laser, EUV, or electron beam can be used as the exposure source. After exposure, post-exposure baking is performed as necessary. Then, development is performed with a developer (e.g., 2.38% by mass aqueous solution of tetramethylammonium hydroxide, butyl acetate), and further rinsing with a rinse solution or pure water to remove the used developer. Then, post-baking is performed to dry the resist pattern and increase adhesion to the underlayer.

The etching process carried out after forming the resist pattern is performed by dry etching.

The following gases can be used for processing the hard mask (silicon-containing layer), resist underlayer film, and _substrate : _CF4 , _CHF3 , _CH2F2 , _CH3F , _C4F6 , _C4F8 , _O2 , _N2O , _NO2 , _H2 , and He. These gases can be used alone or in combination of two or _more . Furthermore, these gases can be mixed with argon, nitrogen, _carbon dioxide, carbonyl sulfide, sulfur dioxide, neon, or nitrogen trifluoride.

The resist film may be patterned by a nanoimprint method or a self-assembled film method.

In the nanoimprint method, a resist composition is shaped using a patterned mold that is transparent to the irradiated light. In the self-assembled film method, a pattern is formed using a self-assembled film that naturally forms a regular structure on the nanometer order, such as a diblock polymer (polystyrene-polymethyl methacrylate).

In the nanoimprint method, before applying the curable composition that will become the resist film, a silicon-containing layer (hard mask layer) may be optionally formed on the resist underlayer film by coating or vapor deposition, and further an adhesion layer may be formed on the resist underlayer film or the silicon-containing layer (hard mask layer) by coating or vapor deposition, and the curable composition that will become the resist film may be applied on the adhesion layer.

In some cases, wet etching is performed to simplify the process and reduce damage to the processed substrate. This leads to suppression of fluctuations in processing dimensions and reduction of pattern roughness, making it possible to process the substrate with good yield. For this reason, in (iii) to (iv) above, the hard mask can be removed by either etching or an alkaline chemical solution. In particular, when an alkaline chemical solution is used, there are no restrictions on the components, but it is preferable for the alkaline components to include the following:

Examples of alkaline components include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltripropylammonium hydroxide, methyltributylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldiethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and (2-hydroxyethyl)trimethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxy)ethanol, N,N-dimethylethanolamine, N,N-diethylethanolamine, N , N-dibutylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, tetrahydrofurfurylamine, N-(2-aminoethyl)piperazine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,4-diazabicyclo[2.2.2]octane, hydroxyethylpiperazine, piperazine, 2-methylpiperazine, trans-2,5-dimethylpiperazine, cis-2,6-dimethylpiperazine, 2-piperidinemethanol, cyclohexylamine, 1,5-diazabicyclo[4,3,0]nonene-5, etc. In particular, from the viewpoint of handling, tetramethylammonium hydroxide and tetraethylammonium hydroxide are particularly preferred, and an inorganic base may be used in combination with a quaternary ammonium hydroxide. As the inorganic base, alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, and rubidium hydroxide are preferred, with potassium hydroxide being more preferred.

The following examples are provided to specifically explain the present invention, but the present invention is not limited to these.

The weight average molecular weights Mw of the resins shown in the following Synthesis Examples 1 to 39 are the results of measurement by gel permeation chromatography (hereinafter abbreviated as GPC). For the measurement, a GPC device manufactured by Tosoh Corporation was used, and the measurement conditions etc. are as follows.
GPC column: TSKgel Super-Multipore HZ-N (2 columns)
Column temperature: 40°C
Solvent: Tetrahydrofuran (THF)
Flow rate: 0.35 ml/min. Standard sample: polystyrene (manufactured by Tosoh Corporation)

The polymers of structural formulae (S1) to (S35) used in the resist underlayer film-forming composition were synthesized using the following compound group A, compound group B, catalyst group C, solvent group D, and reprecipitation solvent group E.
Compound groups A to B

Catalyst group C, Solvent group D, Reprecipitation solvent group E
Methanesulfonic acid: C1
Mercaptopropionic acid: C2
p-Toluenesulfonic acid monohydrate: C3
Propylene glycol monomethyl ether acetate (=PGMEA): D1
Propylene glycol monomethyl ether (=PGME): D2
N-Methyl-2-pyrrolidinone: D3
1,4-dioxane: D4
Methanol: E1
Methanol/water: E2

[Synthesis Examples 1 to 39]
A flask was charged with 8.0 g of A1, 15.5 g of B1, 2.5 g of C1, and 60.6 g of D1. The mixture was then heated under nitrogen until reflux and reacted for about 14 hours. After the reaction was stopped, the mixture was reprecipitated in E2 and dried to obtain resin (S1). The weight average molecular weight Mw measured by GPC in terms of polystyrene was about 3,700. The obtained resin was dissolved in PGMEA to obtain a solution of the target compound. Resins S2 to S40 were synthesized by the same operation, but a solvent in which the resin was soluble was selected for the operation of dissolving the obtained resin again. In addition, the subsequent ion exchange operation was performed for 4 hours using a cation exchange resin and an anion exchange resin as necessary. The results are shown in Table 1 (Tables 1-1 to 1-3), and the structures and weight average molecular weights Mw of resins S1 to S40 are shown below. Resin S10 is excluded from Table 1-1 because it is a purchased product. In addition, in Table 1, the values in the columns "Compound", "Catalyst", and "Solvent" represent the mass (g) of each compound, and the values in the column "Temperature/Time" represent the temperature (°C) and reaction time (hours) during the reaction.

Preparation of resist underlayer film Resins (S1) to (S40), crosslinkers (CL1 to CL3), acid generators (Ad1 to Ad2), solvents (propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CYH)), and Megafac R-40 (manufactured by DIC Corporation, H1) as a surfactant were mixed in the ratios shown in Table 2 below (Tables 2-1 to 2-2), and filtered through a 0.1 μm polytetrafluoroethylene microfilter to prepare compositions for forming resist underlayer films (M1 to M45). The values shown in Table 2 represent the weight ratios of the crosslinker, acid generator, and surfactant when the weight of the resin is 100 parts, and the weight of the solvent represents the weight ratio of each solvent when the total weight of the solvent is 100 wt%, independent of the weight of the resin. In Table 2, "-" indicates that the component is not contained.

The structures of the crosslinking agents (CL1 to CL3) and the acid generators (Ad1 to Ad2) are shown below.

[Preparation of plasma-treated wafers]
[Examples 1 to 48, Comparative Examples 1 to 46]
The resist underlayer film forming compositions M1 to M45 were applied onto a silicon wafer using a coating and developing apparatus manufactured by Tokyo Electron, and baked at a predetermined temperature and for a predetermined time as described in Table 3 (Tables 3-1 to 3-2) to form a resist underlayer film having a film thickness of about 45 nm. Then, a plasma treatment was performed for 10 seconds by bombardment using He using an etching apparatus manufactured by Tokyo Electron. In Example 41, the resist underlayer film forming composition M22 was baked at a temperature different from that of Example 22, and Examples 42 and 43 were obtained by additionally baking Example 29. Wafers that were not subjected to the above-described plasma treatment were also prepared as Comparative Examples 1 to 46.

[Elution test in resist solvent]
The resist underlayer films (Examples 1 to 48) before and after the plasma treatment were immersed in a PGME/PGMEA mixed solution (mass ratio 7/3), which is a general-purpose thinner, for 60 seconds, spin-dried, and baked at 100°C for 30 seconds, and the film thickness was compared before and after immersion in the thinner to confirm the resistance to the solvent. A film thickness reduction rate of 1% or less after immersion in the thinner was judged as "good", and a film thickness reduction rate of more than 1% was judged as "poor". The results are shown in Table 3. In Table 3, "-" indicates that no additional baking was performed, or that the solvent resistance was not evaluated.

As shown in Table 3, when a resist underlayer film that had once exhibited solvent resistance by baking was subjected to plasma treatment, it was confirmed that the solvent resistance was maintained. In addition, even if a resist underlayer film that does not exhibit solvent resistance by baking was subjected to plasma treatment, it was confirmed that the solvent resistance was exhibited. Furthermore, even if additional baking was performed after plasma treatment, the solvent resistance did not change. From the above, it was determined that the film before and after plasma treatment can be used as a resist underlayer film, whether it is a cured film or an uncured film, and can also be used by performing additional baking after plasma treatment.
In the subsequent evaluations, when the same polymer skeleton was used, the changes in the properties of the corresponding skeleton before and after the plasma treatment were compared.

[FT-IR Measurement]
The resist underlayer films (Examples 1 to 48, Comparative Examples 1 to 46) before and after the plasma treatment were subjected to FT-IR measurement under the following measurement conditions using an FT-IR spectrophotometer (Nicoleti S50 manufactured by Thermo FISHER SCIENTIFIC). The area of the peak (1654 cm ^-1 to 1500 cm ^-1 ) corresponding to SP2 carbon and indicating a C=C bond was calculated. The area values were compared by standardizing the area of the peak by (area of 1654 cm ^-1 to 1500 cm ^-1 )/(film thickness) taking into account the film thickness of the measured sample. The film thickness was measured using a vacuum ultraviolet multi-angle spectroscopic ellipsometer, VUV-VASE (registered trademark) manufactured by Woollam Japan. The results are shown in Table 4 (Tables 4-1 to 4-4). In Table 4, "-" indicates that additional baking was not performed after the plasma treatment.

(Measurement conditions)
The coating film on the silicon wafer was measured by a transmission method. A silicon wafer with no coating was used as a blank measurement. The measurement range was 4000 to 700 cm ^-1 , the resolution was 8 cm ^-1 , and the number of integrations was 64.

[Raman analysis]
Raman analysis was performed on the resist underlayer films (Examples 1 to 48, Comparative Examples 1 to 46) before and after the plasma treatment using DXR2 manufactured by Thermo FISHER SCIENTIFIC under the following measurement conditions. The ratio of SP2 carbon (Ig)/SP3 carbon (Id) before and after the plasma treatment was calculated. The SP2 carbon and SP3 carbon were separated into two peaks with peak tops of 1540 cm ^-1 and 1340 cm ^-1 in the range of 1900 to 1020 cm ^-1 to calculate the area value. The area value of the peak top of 1540 cm ^-1 for SP2 carbon and the area value of 1340 cm ^-1 for SP3 carbon. The intensity values were compared by standardizing with (Ig/Id)/(film thickness) taking into account the film thickness of the measured sample, and the intensity ratio Ig/Id was compared. The film thickness was measured using a vacuum ultraviolet multi-angle spectroscopic ellipsometer, VUV-VASE (registered trademark) manufactured by Woollam Japan Co., Ltd. The results are shown in Table 4. In Table 4, "-" indicates that no additional baking was performed after the plasma treatment, and "no intensity" indicates that the Raman activity was low and no peak could be detected.

(Measurement conditions)
The laser used for the Raman measurement had a wavelength of 633 nm (2 mW) and a grating of 600 Lines/mm. The measurement range was 3500 to 250 cm ^-1 , the exposure time was 2 seconds, the number of integrations was 16, and Ig/Id was measured at 100 points and averaged.

[Measurement of Etching Rate]
The resist underlayer films (Examples 1 to 48, Comparative Examples 1 to 46) before and after plasma treatment were etched under the following conditions, the film thickness was measured using a cross-sectional SEM, and the etching rates before and after plasma treatment were calculated from the remaining film amount. Etching resistance was evaluated using (etching rate after plasma treatment)/(etching rate before plasma treatment) as a relative value to the etching rate before plasma treatment. A resist underlayer film with a relative value smaller than 1 can be said to have improved etching resistance. The results are shown in Table 5 (Tables 5-1 to 5-4). In Table 5, "-" indicates that additional baking was not performed.
Etching conditions
Plasma treatment gas: _{octafluorocyclobutane} ( _C4F8 ), oxygen ( _O2 ), argon (Ar)
Processing time: 40 seconds

[Hardness measurement and elastic modulus measurement]
The resist underlayer films (Examples 1 to 48, Comparative Examples 1 to 46) before and after the plasma treatment were evaluated using a nanoscale multifaceted mechanical evaluation system (TI-980 triboindenter, manufactured by Bruker AXS). The hardness and elastic modulus were measured at room temperature with a Berkovich indenter (triangular pyramid) at an indentation depth of 28 nm. The results are shown in Table 5.

[Membrane density measurement]
The film density of the resist underlayer films (Examples 1 to 48 and Comparative Examples 1 to 46) before and after the plasma treatment was measured at room temperature using a fully automatic multipurpose X-ray diffraction device (RIGAKU Corporation, Smart Lab). The results are shown in Table 5.

[Optical constant measurement]
The refractive index (n value) and optical absorption coefficient (k value) of the resist underlayer films (Examples 1 to 48) before and after the plasma treatment were measured at wavelengths of 193 nm and 633 nm using a vacuum ultraviolet multi-angle spectroscopic ellipsometer, VUV-VASE (registered trademark), manufactured by Woollam Japan. The results are shown in Table 6 (Tables 6-1 to 6-2). In order to show the effect of the plasma treatment, the optical constants of the resist underlayer film (comparative example) that was not subjected to the plasma treatment are also listed in the table. In the table, "-" indicates that the plasma treatment was not performed or that the additional baking was not performed.

As shown in Tables 4 and 5, it was confirmed that plasma treatment increases SP2 carbon and improves etching resistance. It was also confirmed that physical parameters such as hardness, film density, and elastic modulus of the resist underlayer film improve with an increase in SP2 carbon. Therefore, the resist underlayer film formed by plasma treatment exhibits properties closer to evaporated films such as amorphous carbon than normal resist underlayer films, and can be used as a replacement for amorphous carbon in advanced processes. In addition, as shown in Table 6, the optical constants change significantly before and after plasma treatment, changing to high n/low k at 193 nm, which is considered preferable for anti-reflection films. Generally, there is a trade-off between high n/low k and etching resistance, but the application of this process can eliminate the trade-off. Therefore, it can be deployed in applications other than just replacing amorphous carbon.

The weight average molecular weight Mw of the resin shown in the following Synthesis Example 40 is a result of measurement by gel permeation chromatography (hereinafter, abbreviated as GPC). For the measurement, a GPC device manufactured by Tosoh Corporation was used, and the measurement conditions, etc. are as follows.
GPC column: TSKgel Super-Multipore HZ-N (2 columns)
Column temperature: 40°C
Solvent: Tetrahydrofuran (THF)
Flow rate: 0.35 ml/min. Standard sample: polystyrene (manufactured by Tosoh Corporation)

The polymer of the structural formula (S41) used in the composition for forming a resist underlayer film was synthesized using the following compound group A, compound group B, catalyst group C, solvent group D, and reprecipitation solvent group E.
Compound groups A to B

Catalyst group C, Solvent group D, Reprecipitation solvent group E
Methanesulfonic acid: C1
Propylene glycol monomethyl ether acetate (=PGMEA): D1
Propylene glycol monomethyl ether (=PGME): D2
Methanol: E1

[Synthesis Example 40]
25.0 g of A8, 10.5 g of B3, 15.5 g of B4, 16.8 g of C1, and 100.0 g of D1 were placed in a flask. Then, the mixture was heated to 110 ° C. under nitrogen and reacted for about 6 hours. After the reaction was stopped, the mixture was reprecipitated with E1 and dried to obtain a resin (S41). The weight average molecular weight Mw measured in terms of polystyrene by GPC was about 3,100. The obtained resin was dissolved in PGMEA to obtain a solution of the target compound. A solvent in which the resin was dissolved was selected for the operation of dissolving the obtained resin again. In addition, the subsequent ion exchange operation was performed for 4 hours using a cation exchange resin and an anion exchange resin as necessary. The results are shown in Table 7, and the structure and weight average molecular weight Mw of resin S41 are shown below. In addition, in Table 7, the values in the columns "Compound", "Catalyst", and "Solvent" represent the mass (g) of each compound, and the values in the column "Temperature/Time" represent the temperature (°C) during the reaction and the reaction time (hours).

Preparation of resist underlayer film Resin (S41), solvent (propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CYH)), and surfactant Megafac R-40 (DIC Corporation, H1) were mixed in the ratios shown in Table 8 below, and filtered through a 0.1 μm polytetrafluoroethylene microfilter to prepare a resist underlayer film forming composition (M46). The values shown in Table 8 represent the weight ratio of the surfactant when the weight of the resin is 100 parts, and the weight of the solvent represents the weight ratio of each solvent when the total weight of the solvent is 100 wt%, independent of the weight of the resin. In Table 8, "-" indicates that the component is not contained.

[Preparation of plasma-treated wafers]
[Example 49, Comparative Example 47]
The composition for forming a resist underlayer film M46 was applied onto a silicon wafer using a coating device manufactured by Brewer Science and a hot plate, and baked at a predetermined temperature for a predetermined time as shown in Table 9 to form a resist underlayer film with a film thickness of about 65 nm. Thereafter, a plasma treatment using He was performed using a plasma treatment device under the predetermined conditions as shown in Table 9. In addition, a wafer that was not subjected to the above-mentioned plasma treatment was also prepared as Comparative Example 47. In addition, "-" in the table indicates that the plasma treatment was not performed.

[Elution test in resist solvent]
The resist underlayer film (Example 49) before and after plasma treatment was immersed in a PGME/PGMEA mixed solution (mass ratio 7/3) which is a general-purpose thinner for 60 seconds, spin-dried, and baked at 100°C for 30 seconds, and the film thickness was compared before and after immersion in the thinner to confirm the resistance to the solvent. When the film thickness reduction rate before and after immersion in the thinner was within 1%, it was judged as "good", and when the film thickness reduction rate was more than 1%, it was judged as "bad". The results are shown in Table 10.

As shown in Table 10, it was confirmed that the solvent resistance was maintained when a plasma treatment was performed on a resist underlayer film that had once exhibited solvent resistance by baking. It was determined that the film before and after the plasma treatment can be used as a resist underlayer film regardless of whether it is a cured film or an uncured film, and can also be used by additional baking after the plasma treatment.
In the subsequent evaluations, when the same polymer skeleton was used, the changes in the properties of the corresponding skeleton before and after the plasma treatment were compared.

[FT-IR Measurement]
The resist underlayer film (Example 49, Comparative Example 47) before and after the plasma treatment was subjected to FT-IR measurement under the following measurement conditions using an FT-IR spectrophotometer (NicoletiS50 manufactured by Thermo FISHER SCIENTIFIC). The area of the peak (1654 cm ^-1 to 1500 cm ^-1 ) corresponding to SP2 carbon and indicating C=C bonds was calculated, and the case where the area value of the same peak was increased compared to before the plasma treatment (the case where SP2 carbon has increased) was judged as "good". The area values were compared by standardizing the area/film thickness of 1654 cm ^-1 to 1500 cm ^-1 taking into account the film thickness of the measured sample. The film thickness was measured using a vacuum ultraviolet multi-angle spectroscopic ellipsometer, VUV-VASE (registered trademark) manufactured by Woollam Japan. The results are shown in Table 11. In Table 11, "x" in the FT-IR column means that no plasma treatment was performed, and the area value of the above peak is that of the resist underlayer film after baking at the specified temperature for the specified time shown in Table 9.

(Measurement conditions)
The coating film on the silicon wafer was measured by a transmission method. A silicon wafer with no coating was used as a blank measurement. The measurement range was 4000 to 700 cm ^-1 , the resolution was 8 cm ^-1 , and the number of integrations was 64.

[Raman analysis]
The resist underlayer film before and after the plasma treatment (Example 49, Comparative Example 47) was subjected to Raman analysis under the following measurement conditions using DXR2 manufactured by Thermo FISHER SCIENTIFIC. The ratio of SP2 carbon (Ig)/SP3 carbon (Id) before and after the plasma treatment was calculated, and the case where the ratio of SP2 carbon/SP3 carbon was increased compared to before the plasma treatment (the case where the proportion of SP2 carbon was increased) was judged to be "good". In addition, the area value of SP2 carbon and SP3 carbon was calculated by peak separation treatment at two peaks with peak tops of 1540 cm ^-1 and 1340 cm ^-1 in the range of 1900 to 1020 cm ^-1 . The area value of the peak top of SP2 carbon was set to 1540 cm ^-1 for the area of SP2 carbon, and the area value of the peak top of SP3 carbon was set to 1340 cm ^-1 for the area of SP3 carbon. The results are shown in Table 11. In Table 11, an "x" in the Raman analysis column means that no plasma treatment was performed, and therefore the ratio of SP2 carbon (Ig)/SP3 carbon (Id) (also referred to as "Ig/Id") is that of the resist underlayer film after baking at the specified temperature for the specified time shown in Table 9.

(Measurement conditions)
The laser used for the Raman measurement had a wavelength of 633 nm (2 mW) and a grating of 600 Lines/mm. The measurement range was 3500 to 250 cm ^-1 , the exposure time was 2 seconds, the number of integrations was 16, and Ig/Id was measured at 100 points and averaged.

[Measurement of Etching Rate]
The resist underlayer film (Example 49, Comparative Example 47) before and after plasma treatment was etched under the following conditions, the film thickness was calculated using a cross-sectional SEM, and the etching resistance was evaluated from the remaining film amount. When the etching rate was slower than before plasma treatment (when the etching resistance was higher), it was judged as "Good". The results are shown in Table 12. In Table 12, "X" in the etching rate column means that the plasma treatment was not performed, and therefore the etching rate is that of the resist underlayer film after baking at the specified temperature for the specified time shown in Table 9.
Etching conditions
Plasma treatment gas: tetrafluoromethane ( _CF4 ), oxygen ( _O2 ), nitrogen (N2)
Processing time: 20 seconds

[Hardness measurement]
The resist underlayer film (Example 49, Comparative Example 47) before and after the plasma treatment was evaluated using a nanoscale multifaceted mechanical evaluation system (TI-980 triboindenter, manufactured by Bruker AXS). A Berkovich indenter (triangular pyramid) was used for the measurement, and the hardness was evaluated up to a depth of 45 nm, and the case where the hardness was higher than that before the plasma treatment was judged to be "good". The results are shown in Table 12. In Table 12, "x" in the hardness column means that the hardness is that of the resist underlayer film after baking at the specified temperature and for the specified time shown in Table 9, since no plasma treatment was performed.

[Membrane density measurement]
The film density of the resist underlayer film before and after the plasma treatment (Example 49, Comparative Example 47) was measured using a fully automatic multipurpose X-ray diffraction device (RIGAKU Corporation, Smart Lab). The film density was determined to be "good" when it was higher than that before the plasma treatment. The results are shown in Table 12. In Table 12, "x" in the density column means that the film density is that of the resist underlayer film after baking at the specified temperature for the specified time shown in Table 9, since the plasma treatment was not performed.

[Optical constant measurement]
The refractive index (n value) and optical absorption coefficient (k value) of the resist underlayer film (Example 49) before and after the plasma treatment were measured at wavelengths of 193 nm and 633 nm using a vacuum ultraviolet multi-angle spectroscopic ellipsometer, VUV-VASE (registered trademark), manufactured by Woollam Japan Co., Ltd. The results are shown in Table 13. In order to show the effect of the plasma treatment, the optical constants of the resist underlayer film (Comparative Example 47) that was not subjected to the plasma treatment are also shown in the table.

 

 

Claims (27)

A plasma-treated resist underlayer film comprising a resin (I) containing a structural unit represented by the following formula (1):

(In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.) The plasma-treated resist underlayer film according to claim 1, wherein the resin (I) is a resin obtained by a reaction that generates a covalent bond between a carbon atom constituting the aromatic ring of the C in the formula (1) and a carbon atom of the D. The resin (I) contains a resin (G) having a composite unit structure,
the composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms,
the resin (G) is a resin obtained by a reaction for forming a covalent bond between a carbon atom constituting the aromatic ring of the unit structure (A) and a carbon atom in the unit structure (B),
2. The plasma-treated resist underlayer film according to claim 1, wherein the unit structure (A) has a skeleton having an aromatic ring, and the skeleton is at least any one of an aromatic amine skeleton, a nitrogen-containing aromatic heterocyclic skeleton, and an aromatic ring skeleton having a hydroxy group bonded to the aromatic ring. The plasma-treated resist underlayer film according to claim 1, in which the intensity ratio Ig/Id of the G band to the D band as determined by Raman spectroscopy is 0.1 to 10.0. ^2. The plasma-treated resist underlayer film according to claim 1, having a film density of 1.0 to 2.5 g/cm3. The plasma-treated resist underlayer film according to claim 1, which has a refractive index of 1.3 to 2.5 or an optical absorption coefficient of 0.2 to 1.0 at a wavelength of 193 nm, or a refractive index of 1.5 to 3.5 or an optical absorption coefficient of 0 to 0.2 at a wavelength of 633 nm. The plasma-treated resist underlayer film according to claim 1, in which the peak area of the carbon-carbon double bond absorption peak measured by infrared spectroscopy of the plasma-treated resist underlayer film after plasma treatment is 1.01 times or more larger than the peak area of the carbon-carbon double bond absorption peak measured by infrared spectroscopy of the resist underlayer film before plasma treatment. The plasma-treated resist underlayer film according to claim 1, having an elastic modulus of 50 GPa or more. A composition for forming a resist underlayer film for forming the plasma-treated resist underlayer film according to claim 1, the composition for forming a resist underlayer film comprising the resin (I) and a solvent. The composition for forming a resist underlayer film according to claim 9, wherein the solvent contains at least one selected from the group consisting of a carboxylic acid having a hydroxy group, a linear or cyclic alkyl ketone, a cyclic lactone, an alkylene glycol monoalkyl ether, a monocarboxylic acid ester of an alkylene glycol monoalkyl ether, and an alkoxycarboxylic acid ester of an alkylene glycol monoalkyl ether. The composition for forming a resist underlayer film according to claim 9 or 10, wherein the solvent includes a solvent having a boiling point of 160°C or higher. The composition for forming a resist underlayer film according to claim 9 or 10, further comprising at least one selected from the group consisting of an acid, a salt thereof, and an acid generator. The composition for forming a resist underlayer film according to claim 9 or 10, further comprising a crosslinking agent. The composition for forming a resist underlayer film according to claim 9 or 10, further comprising a surfactant. forming a coating film on a semiconductor substrate using a composition for forming a resist underlayer film;
and forming a plasma-treated resist underlayer film, in which the coating film is subjected to a plasma treatment to increase the intensity ratio Ig/Id of G band to D band as determined by Raman spectroscopy, increase the peak area of the absorption peak of a carbon-carbon double bond as determined by infrared spectroscopy, increase the refractive index at a wavelength of 193 nm or 633 nm, or decrease the optical absorption coefficient at a wavelength of 193 nm;
The composition for forming a resist underlayer film comprises a resin (I) having a structural unit represented by the following formula (1) and a solvent:

(In formula (1), C represents a structure having an aromatic ring, D represents a structure having one or more carbon atoms, and * represents a bond.) The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the resin (I) is a resin obtained by a reaction that generates a covalent bond between a carbon atom constituting the aromatic ring of the C in the formula (1) and a carbon atom of the D. The resin (I) contains a resin (G) having a composite unit structure,
the composite unit structure has a unit structure (A) having an aromatic ring and a unit structure (B) having one or more carbon atoms,
the resin (G) is a resin obtained by a reaction for forming a covalent bond between a carbon atom constituting the aromatic ring of the unit structure (A) and a carbon atom in the unit structure (B),
16. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the unit structure (A) has a skeleton having an aromatic ring, and the skeleton is at least any one of an aromatic amine skeleton, a nitrogen-containing aromatic heterocyclic skeleton, and an aromatic ring skeleton having a hydroxy group bonded to the aromatic ring. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the intensity ratio Ig/Id of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more as compared to the intensity ratio Ig/Id of the pre-plasma-treated resist underlayer film before the plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the hardness of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more the hardness of the pre-plasma-treated resist underlayer film before the plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the film density of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more the film density of the pre-plasma-treated resist underlayer film before the plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 193 nm is 1.01 times or more relative to the refractive index of the pre-plasma-treated resist underlayer film before the plasma treatment at a wavelength of 193 nm, or the optical absorption coefficient of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 193 nm is 0.99 times or less relative to the optical absorption coefficient of the pre-plasma-treated resist underlayer film before the plasma treatment at a wavelength of 193 nm, or the refractive index of the plasma-treated resist underlayer film after the plasma treatment at a wavelength of 633 nm is 1.01 times or more relative to the refractive index of the pre-plasma-treated resist underlayer film before the plasma treatment at a wavelength of 633 nm. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the peak area of the carbon-carbon double bond absorption peak measured by infrared spectroscopy of the plasma-treated resist underlayer film after plasma treatment is 1.01 times or more larger than the peak area of the carbon-carbon double bond absorption peak measured by infrared spectroscopy of the resist underlayer film before plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the elastic modulus of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more greater than the elastic modulus of the pre-plasma-treatment resist underlayer film before the plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the etching resistance of the plasma-treated resist underlayer film after the plasma treatment is 1.01 times or more higher than the etching resistance of the resist underlayer film before the plasma treatment. The method for producing a plasma-treated resist underlayer film according to claim 15, wherein the gas used in the plasma treatment includes at least a rare gas, nitrogen, and hydrogen. The method for producing a plasma-treated resist underlayer film according to claim 15, further comprising a step of baking the semiconductor substrate on which the plasma-treated resist underlayer film is formed at 400°C or higher after the plasma treatment. A semiconductor substrate;
A laminate comprising the plasma-treated resist underlayer film according to any one of claims 1 to 8.