JP2025110048A - Radiation sensitive composition, cured film, display element, and method for producing cured film - Google Patents

Abstract

The main object of the present invention is to provide a radiation-sensitive composition capable of forming a cured film having excellent radiation sensitivity, melt flow resistance, dielectric constant, and chemical resistance.
[Solution] The present invention relates to a radiation-sensitive composition containing a polymer component (A), a quinone diazide compound (B), and a solvent (C), in which the polymer component (A) contains at least one structural unit (I) selected from the group consisting of structural units having an acid group and structural units derived from maleimide, a structural unit (II) containing an alicyclic epoxy group, and a structural unit (III) (excluding the structural unit (II)) derived from a (meth)acrylate having an alicyclic structure, in the same polymer or different polymers, and the structural unit (II) accounts for 10 mass% or more of all structural units constituting the polymer component (A), and the structural unit (III) accounts for 10 mass% or more of all structural units constituting the polymer component (A).
[Selection diagram] None

Description

The present invention relates to a radiation-sensitive composition, a cured film, a display device, and a method for producing the cured film.

Display elements are provided with insulating cured films such as interlayer insulating films that insulate between wiring and a substrate or between wiring, planarizing films, and partition walls. The cured films are generally formed by subjecting a coating film formed from a radiation-sensitive composition to exposure and development treatments, and then subjecting it to a heat treatment for thermal curing.

As a material for forming such a cured film, a photosensitive resin composition containing an acrylic copolymer obtained by copolymerizing an unsaturated carboxylic acid, an epoxy group-containing unsaturated compound, and an olefin-based unsaturated compound in a specific ratio, a quinone diazide compound, a solvent, and a specific silane-based surfactant is known (see, for example, Patent Document 1).

JP 2007-156471 A

In recent years, due to changes in panel and element structures, there is a demand for even lower dielectric constants for the cured films (e.g., planarizing films and interlayer insulating films) used in displays such as organic light-emitting diodes (OLEDs) and liquid crystal displays (LCDs). In addition, exposure sensitivity is becoming increasingly important in order to increase productivity.

As a method for reducing the dielectric constant of a cured film, a method of introducing functional groups with low molar polarization into the components of the composition that forms the cured film is known. However, depending on the type of functional group introduced, the hydrophilicity of the composition for forming the cured film may decrease, resulting in reduced developability and exposure sensitivity. In other words, with conventional compositions for forming cured films, it was difficult to achieve both low dielectric constant and cured film properties such as developability, radiation sensitivity, and chemical resistance.

The present invention has been made in consideration of the above problems, and has as its main object to provide a radiation-sensitive composition capable of forming a cured film having excellent radiation sensitivity, melt flow resistance, dielectric constant, and chemical resistance.

The present invention provides the following radiation-sensitive composition, cured film, display device, and method for producing the cured film.

In one embodiment, the present invention comprises:
A polymer component (A),
A quinone diazide compound (B),
A solvent (C);
A radiation-sensitive composition comprising:
The polymer component (A) is
A structural unit (I) having an acid group;
A structural unit (II) containing an alicyclic epoxy group;
A structural unit (III) derived from a (meth)acrylate having an alicyclic structure (excluding the structural unit (II)),
in the same or different polymers,
The structural unit (II) accounts for 10 mass% or more of all structural units constituting the polymer component (A),
The radiation-sensitive composition relates to the above-mentioned structural unit (III) which accounts for 10 mass % or more of all structural units constituting the polymer component (A).

In another embodiment, the present invention comprises:
applying the radiation-sensitive composition onto a substrate;
removing the solvent from the applied radiation-sensitive composition;
a step of exposing the radiation-sensitive composition from which the solvent has been removed to radiation;
developing the radiation-exposed radiation-sensitive composition;
thermally curing the developed radiation-sensitive composition;
The present invention relates to a method for producing a cured film, comprising the steps of:

In another embodiment, the present invention comprises:
The present invention also relates to a cured film formed using the radiation-sensitive composition, and a display device including the cured film.

The radiation-sensitive composition of the present invention contains a polymer component (A) that contains a specific amount of a structural unit (II) that contains an alicyclic epoxy group and a structural unit (III) derived from a (meth)acrylate having an alicyclic structure, and thereby the glass transition temperature of the polymer can be increased while maintaining high radiation sensitivity. As a result, the melt flow is suppressed, the pattern shape is good, and the relative dielectric constant can be sufficiently reduced, making it possible to form a cured film with excellent chemical resistance.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to these embodiments.

Below, matters related to the embodiments will be explained in detail. In this specification, a numerical range described using "~" means that the numerical range includes the numerical range before and after "~" as the lower and upper limits. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and is a unit that is contained in at least two units in the main chain structure.

In this specification, the term "hydrocarbon group" includes chain-shaped hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain-shaped hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a cyclic structure in the main chain and are composed only of a chain structure. However, the chain-shaped hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" means a hydrocarbon group that includes only an alicyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. However, the alicyclic hydrocarbon group does not necessarily have to be composed only of an alicyclic hydrocarbon structure, and also includes those that have a chain structure as a part of it. The term "aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon group does not necessarily have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part of it. The ring structure of the alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent consisting of a hydrocarbon structure. The term "cyclic hydrocarbon" includes alicyclic hydrocarbons and aromatic hydrocarbons.

In this specification, "(meth)acrylo" includes "acrylo" and "methacrylo", and "(meth)acrylic" includes "acrylic" and "methacrylic". "(meth)acrylate" includes "acrylate" and "methacrylate".

≪Radiation-sensitive composition≫
The curable composition according to the present embodiment (hereinafter also referred to as “the present composition”) is
A polymer component (A),
A quinone diazide compound (B),
A solvent (C);
A radiation-sensitive composition comprising:
The polymer component (A) is
A structural unit (I) having an acid group;
A structural unit (II) containing an alicyclic epoxy group;
A structural unit (III) derived from a (meth)acrylate having an alicyclic structure (excluding the structural unit (II)),
in the same or different polymers,
The structural unit (II) accounts for 10 mass% or more of all structural units constituting the polymer component (A),
The radiation-sensitive composition relates to the above-mentioned structural unit (III) which accounts for 10 mass % or more of all structural units constituting the polymer component (A).

The components contained in the composition and other components that may be added as necessary are described below. Unless otherwise specified, each component may be used alone or in combination of two or more types.

<Polymer component (A)>
The polymer component (A) is an aggregate of polymers containing the structural units (I) to (III). These structural units may be contained in the same polymer, or these structural units may be contained in different polymers. The polymers constituting the polymer component (A) as a whole may contain the structural units (I) to (III). Therefore, the polymer component (A) may be composed of one type of polymer, or may be composed of two or more types of polymers, so long as it contains the structural units (I) to (III). The polymer component (A) may contain structural units other than the structural units (I) to (III). The polymer component (A) may further contain a polymer that does not have any of the structural units (I) to (III).

(Structural Unit (I))
The polymer component (A) contains a polymer containing the structural unit (I), and thus the polymer component can be imparted with good alkali solubility. In this specification, "alkali soluble" means that the polymer component is soluble in an alkaline aqueous solution such as a 2.38 mass% aqueous solution of tetramethylammonium hydroxide.

The structural unit (I) is at least one structural unit selected from the group consisting of a structural unit (I-1) having an acid group and a structural unit (I-2) derived from maleimide.

The structural unit (I-1) is not particularly limited as long as it has an acid group. Examples of the acid group include a carboxy group, a sulfonic acid group, and a phenolic hydroxyl group. Specifically, the structural unit (I) is preferably at least one selected from the group consisting of a structural unit having a carboxy group, a structural unit having a phenolic hydroxyl group, and a structural unit having a sulfonic acid group, and more preferably at least one selected from the group consisting of a structural unit having a carboxy group and a structural unit having a phenolic hydroxyl group. In this specification, the term "phenolic hydroxyl group" refers to a hydroxyl group that is directly bonded to an aromatic ring (e.g., a benzene ring, a naphthalene ring, an anthracene ring, etc.).

The structural unit (I-1) is not particularly limited, but from the viewpoint of copolymerizability, it is preferable that the structural unit (I-1) is a structural unit derived from an unsaturated monomer having an acid group.

Specific examples of monomers that give structural unit (I-1) include monomers that give structural units having a carboxy group, such as unsaturated monocarboxylic acids (e.g., (meth)acrylic acid, crotonic acid, 4-vinylbenzoic acid, etc.); unsaturated dicarboxylic acids (e.g., maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, etc.); monomers that give structural units having a sulfonic acid group, such as vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, (meth)acryloyloxyethyl sulfonic acid, etc.; and monomers that give structural units having a phenolic hydroxyl group, such as 4-hydroxystyrene, o-isopropenylphenol, m-isopropenylphenol, p-isopropenylphenol, hydroxyphenyl (meth)acrylate, etc.

The structural unit (I-2) is a structural unit derived from maleimide. A structural unit derived from maleimide refers to a structural unit derived from an unsubstituted maleimide as shown in the following formula.

As the structural unit (I), the structural unit (I-1) is preferred.

In the polymer component (A), the content of the structural unit (I) (the total content when multiple types are included) is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and particularly preferably 10% by mass or more, based on all structural units constituting the polymer component (A), from the viewpoint of imparting good solubility in an alkaline developer. In addition, from the viewpoint of sufficiently generating a difference in solubility in an alkaline developer between the exposed portion and the unexposed portion and obtaining a pattern with a good shape, the content of the structural unit (I) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on all structural units constituting the polymer component (A).

(Structural Unit (II))
When the polymer component (A) contains a polymer containing the structural unit (II), a cured film having excellent melt flow resistance and chemical resistance can be formed.

The alicyclic epoxy group refers to a group having a structure in which an epoxy group is formed by two adjacent carbon atoms and an oxygen atom that constitute the alicyclic group. Examples of the alicyclic epoxy group include a 2,3-epoxycyclobutyl group, a 2,3-epoxycyclopentyl group, a 3,4-epoxycyclohexyl group, a 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decane-yl group, a 5,6-epoxytricyclo[5.2.1.0 ^2,6 ]decane-yl group, and a 2,3-epoxytricyclo[4.2.1.0 ^2,5 ]nonane-yl group. Among these, a 3,4-epoxycyclohexyl group and a 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decane-yl group are preferred.

Examples of monomers that provide structural unit (II) include vinyl compounds having an alicyclic epoxy group and (meth)acrylates having an alicyclic epoxy group, and among these, (meth)acrylates having an alicyclic epoxy group are preferred.

The structural unit (II) is preferably a structural unit represented by any one of the following formulae (II-1) to (II-3).

Each R ¹ independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and is preferably a hydrogen atom or a methyl group.

Each ^L1 is independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of divalent hydrocarbon groups having 1 to 20 carbon atoms include divalent linear hydrocarbon groups having 1 to 20 carbon atoms, divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

Examples of divalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkanediyl groups such as methanediyl, ethanediyl, propanediyl, and butanediyl groups, alkenediyl groups such as ethenediyl, propenediyl, and butenediyl groups, and alkynediyl groups such as ethynediyl, propynediyl, and butynediyl groups.

Examples of divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include divalent monocyclic alicyclic saturated hydrocarbon groups such as cyclopentanediyl group and cyclohexanediyl group, divalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenediyl group and cyclohexenediyl group, divalent polycyclic alicyclic saturated hydrocarbon groups such as norbornanediyl group, adamantanediyl group and tricyclodecanediyl group, and divalent polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenediyl group and tricyclodecenediyl group.

Examples of divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include arenediyl groups such as benzenediyl, toluenediyl, xylylenediyl, naphthalenediyl, and anthracenediyl groups, and arenediylalkanediyl groups such as benzenediylmethanediyl, benzenediylethanediyl, naphthalenediylmethanediyl, and anthracenediylmethanediyl groups.

n is an integer from 1 to 5, preferably an integer from 1 to 3, and more preferably 1 or 2.

k1 is 0 or 1.

^X1 is a hydroxy group, a halogen atom, a cyano group, a nitro group, an alkyl group, or an alkoxy group.

As the alkyl group, an alkyl group having 1 to 10 carbon atoms and represented by R ¹¹ to R ¹³ in formula (1) described later can be suitably used. As the alkoxy group, an alkoxy group having 1 to 6 carbon atoms and represented by R ¹¹ to R ¹³ in formula (1) described later can be suitably used.

a1 is an integer of 0 to 3. When a1 is 2 or more, the multiple ^X1s are the same or different.

Specific examples of the structural unit (II) include, but are not limited to, those shown below.
(In the formula, R ¹ has the same meaning as in formulas (II-1) to (II-3) above.)

The content of the structural unit (II) (the total content when multiple types are included) is 10% by mass or more, more preferably 12% by mass or more, and even more preferably 15% by mass or more, based on all structural units constituting the polymer component (A). The content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. By setting the content of the structural unit (II) within the above range, a cured film having excellent melt flow resistance and chemical resistance can be formed.

(Structural unit (III))
When the polymer component (A) contains a polymer containing the structural unit (III), a cured film having excellent dielectric constant and chemical resistance can be formed.

Structural unit (III) is a structural unit derived from a (meth)acrylate having an alicyclic structure, excluding those that correspond to structural unit (II).

Examples of alicyclic structures include alicyclic structures having 3 to 20 ring members.

The alicyclic structure having 3 to 20 ring members is not particularly limited as long as it has an alicyclic structure, and may have a monocyclic, bicyclic, tricyclic, tetracyclic or more polycyclic structure, a bridged ring structure, a spiro ring structure, a ring assembly structure in which multiple rings are directly bonded with single bonds or double bonds, or a combination of these. Among these, a monocyclic, bicyclic or tricyclic bridged ring structure is preferred, and cyclopentane, cyclohexane, norbornane, adamantane, and tricyclo[5.2.1.0 ^2,6 ]decane are preferred, and among these, monocyclic structures such as cyclopentane and cyclohexane are more preferred from the viewpoint of radiation sensitivity.

The structural unit (III) is preferably a structural unit represented by any one of the following formulae (III-1) to (III-4).

Each ^R2 independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and preferably a hydrogen atom or a methyl group.

Each ^L2 is independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. As the divalent hydrocarbon group having 1 to 20 carbon atoms, the same divalent hydrocarbon group having 1 to 20 carbon atoms as represented by ^L1 in the above formulas (II-1) to (II-3) can be suitably used.

p is an integer from 1 to 5, preferably an integer from 1 to 3, and more preferably 1 or 2.

k2 is 0 or 1.

^X2 is a hydroxy group, a halogen atom, a cyano group, a nitro group, an alkyl group, or an alkoxy group. As the alkyl group or alkoxy group, those exemplified as ^X1 in the above formulae (II-1) to (II-3) can be suitably used.

a2 is an integer of 0 to 3. When a2 is 2 or more, the multiple ^X2's are the same or different.

Specific examples of the structural unit (III) include, but are not limited to, those shown below.
(In the formula, ^R2 has the same meaning as in formulas (III-1) to (III-4) above.)

The content of the structural unit (III) (the total content when multiple types are included) is 10% by mass or more, more preferably 12% by mass or more, and even more preferably 15% by mass or more, based on all structural units constituting the polymer component (A). The content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. By setting the content of the structural unit (III) within the above range, a cured film having excellent relative dielectric constant and radiation sensitivity can be formed.

(Structural unit IV)
The polymer component (A) may further contain a structural unit (IV) having an alkoxysilyl group. Examples of the alkoxysilyl group include a group represented by the following formula (1).
(In formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, provided that at least one of R ¹¹ , R ¹² and R ¹³ is an alkoxy group having 1 to 6 carbon atoms. "*" represents a bond.)

In the above formula (1), examples of the alkoxy group having 1 to 6 carbon atoms represented by R ¹¹ to R ¹³ include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a tert-butoxy group, etc. Of these, the alkoxy group represented by R ¹¹ to R ¹³ preferably has 1 to 3 carbon atoms, and more preferably is a methoxy group or an ethoxy group.

The alkyl group having 1 to 10 carbon atoms represented by R ¹¹ to R ¹³ may be linear or branched. Examples of the alkyl group having 1 to 10 carbon atoms represented by R ¹¹ to R ¹³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, etc. Of these, the alkyl group represented by R ¹¹ to R ¹³ is preferably a methyl group, an ethyl group, or a propyl group.

One of the groups represented by R ¹¹ to R ¹³ is an alkoxy group having 1 to 6 carbon atoms. The remaining group is preferably a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, more preferably a hydroxy group, an alkoxy group having 1 to 3 carbon atoms, or an alkyl group having 1 to 3 carbon atoms, and even more preferably an alkoxy group having 1 to 3 carbon atoms, or an alkyl group having 1 to 3 carbon atoms.

Of R ¹¹ to R ¹³ , two or more are preferably alkoxy groups having 1 to 6 carbon atoms, and all are more preferably alkoxy groups having 1 to 6 carbon atoms.

The structural unit (IV) is preferably a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond (hereinafter also referred to as an "unsaturated monomer"), and more specifically, is preferably at least one selected from the group consisting of a structural unit represented by the following formula (1-1) and a structural unit represented by the following formula (1-2).
(In formula (1-1) and formula (1-2),
R ^A is a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group.
^R7 and ^R8 each independently represent a divalent aromatic ring group or a chain hydrocarbon group.
R ¹¹ , R ¹² and R ¹³ are the same as those in formula (1).

In the above formulas (1-1) and (1-2), the divalent aromatic ring group of R ⁷ and R ⁸ is preferably a substituted or unsubstituted phenylene group or a substituted or unsubstituted naphthylene group. The divalent chain hydrocarbon group is preferably an alkanediyl group having 1 to 6 carbon atoms, more preferably an alkanediyl group having 1 to 4 carbon atoms, and even more preferably a linear alkanediyl group having 1 to 4 carbon atoms.

Specific examples of monomers that provide structural unit (IV) include styryltrimethoxysilane, styryltriethoxysilane, styrylmethyldimethoxysilane, styrylethyldiethoxysilane, styryldimethoxyhydroxysilane, styryldiethoxyhydroxysilane, (meth)acryloxyphenyltrimethoxysilane, (meth)acryloxyphenyltriethoxysilane, (meth)acryloxyphenylmethoxydimethoxysilane, (meth)acryloxyphenylethyldiethoxysilane, etc.; trimethoxy(4-vinylnaphthyl) silane, triethoxy(4-vinylnaphthyl)silane, methyldimethoxy(4-vinylnaphthyl)silane, ethyldiethoxy(4-vinylnaphthyl)silane, (meth)acryloxynaphthyltrimethoxysilane, etc.; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 4-(meth)acryloxybutyltrimethoxysilane, etc. Among these, styryltrimethoxysilane, styryltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 4-(meth)acryloxybutyltrimethoxysilane are preferred, and 3-(meth)acryloxypropyltrimethoxysilane and 3-(meth)acryloxypropyltriethoxysilane are more preferred.

When polymer component (A) contains the structural unit (IV), the content of the structural unit (IV) (the total content when multiple types are contained) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, based on all structural units constituting polymer component (A). The content is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. By setting the content of structural unit (IV) within the above range, a cured film having excellent radiation sensitivity and chemical resistance can be obtained, which is preferable.

The polymer component (A) may further contain structural units other than the structural units (I) to (IV). Examples of the other structural units include structural unit (V) derived from an aromatic vinyl compound, structural unit (VI) derived from an N-substituted maleimide compound, structural unit (VII) having a hydroxyl group, structural unit (VIII) derived from an alkyl methacrylate ester compound, and structural unit (IX) having an epoxy group (excluding those corresponding to structural unit (II)). By including at least one of structural unit (V) and structural unit (VI) in polymer component (A), the glass transition temperature (Tg) of polymer component (A) can be further increased, which is advantageous in that the effect of improving the pattern shape can be enhanced.

(Structural Unit (V))
The aromatic vinyl compound constituting the structural unit (V) is not particularly limited, but examples thereof include styrene-based compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 5-t-butyl-2-methylstyrene, divinylbenzene, trivinylbenzene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, and diphenylethylene; vinylnaphthalene-based compounds such as vinylnaphthalene and divinylnaphthalene; and heterocyclic vinyl compounds such as vinylpyridine. Of these, the aromatic vinyl compound is preferably a styrene-based compound.

When the polymer component (A) contains the structural unit (V), the content of the structural unit (V) (the total content when multiple types are contained) is preferably 0.5% by mass or more, and more preferably 1% by mass or more, based on all structural units constituting the polymer component (A). The content is preferably 30% by mass or less, and more preferably 25% by mass or less. By setting the content of the structural unit (V) within the above range, a cured film with a better pattern shape can be obtained, and the glass transition temperature of the polymer component (A) does not become too high, thereby suppressing a decrease in developability, which is preferable.

(Structural Unit (VI))
The N-substituted maleimide compound constituting the structural unit (VI) may be a compound in which a hydrogen atom bonded to a nitrogen atom of a maleimide is substituted with a monovalent hydrocarbon group. Examples of the monovalent hydrocarbon group include a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, and a monovalent aromatic hydrocarbon group. Of these, in terms of being able to further enhance the effect of improving heat resistance, the N-substituted maleimide compound constituting the structural unit (VI) preferably has a monovalent cyclic hydrocarbon group, and more preferably has a monovalent alicyclic hydrocarbon group having a monocycle, a bridged ring, or a spiro ring.

Specifically, the structural unit (VI) is preferably a structural unit represented by the following formula (2).
(In formula (2),
^R5 is a monovalent cyclic hydrocarbon group.
R ⁶ and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

In the above formula (2), ^R5 may be a ring structure of the cyclic hydrocarbon group that is directly bonded to the nitrogen atom, or the ring structure may be bonded via a divalent linking group. Examples of the divalent linking group include a methylene group, an ethylene group, and an alkanediyl group such as a 1,3-propanediyl group. Of these, ^R5 is preferably a ring structure of the cyclic hydrocarbon group that is directly bonded to the nitrogen atom, and more preferably an alicyclic hydrocarbon group in which an alicyclic hydrocarbon structure is directly bonded to the nitrogen atom. ^R6 and ^R7 are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

Specific examples of N-substituted maleimide compounds include compounds having an alicyclic hydrocarbon group, such as N-cyclohexylmaleimide, N-cyclopentylmaleimide, N-(2-methylcyclohexyl)maleimide, N-(4-methylcyclohexyl)maleimide, N-(4-ethylcyclohexyl)maleimide, N-(2,6-dimethylcyclohexyl)maleimide, N-norbornylmaleimide, N-tricyclodecylmaleimide, and N-adamantylmaleimide; and compounds having an aromatic hydrocarbon group, such as N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(4-ethylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-benzylmaleimide, and N-naphthylmaleimide. Of these, the N-substituted maleimide compound is preferably at least one selected from the group consisting of N-cyclohexylmaleimide, N-(4-methylcyclohexyl)maleimide, N-phenylmaleimide, and N-(4-methylphenyl)maleimide, and more preferably N-cyclohexylmaleimide.

When polymer component (A) contains the structural unit (VI), the content of the structural unit (VI) (the total content when multiple types are contained) is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on all structural units constituting polymer component (A), from the viewpoint of improving melt flow resistance. From the viewpoint of radiation sensitivity, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

(Structural unit (VII))
The structural unit (VII) is preferably a structural unit derived from an unsaturated monomer having a hydroxyl group (alcoholic hydroxyl group), and specifically includes a structural unit derived from a monomer having one or more hydroxyl groups bonded to a saturated chain hydrocarbon group. The polymer component (A) containing the structural unit (VII) is preferable in terms of suppressing the decrease in pattern forming ability caused by the variation in pre-bake temperature during film formation, forming a good pattern, and in terms of radiation sensitivity. The structural unit (VII) is not particularly limited, and examples thereof include (meth)acrylic compounds and maleimide compounds.

Specific examples of structural unit (VII) include (meth)acrylic compounds such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and glycerol mono(meth)acrylate; and maleimide compounds such as N-(hydroxymethyl)maleimide, N-(2-hydroxyethyl)maleimide, and N-(3-hydroxypropyl)maleimide.

When polymer component (A) contains the structural unit (VII), the content of the structural unit (VII) (the total content when multiple types are contained) is 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on all structural units constituting polymer component (A), from the viewpoint of suppressing a decrease in pattern forming ability due to variations in pre-baking temperature. The content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of suppressing a decrease in developability.

(Structural unit (VIII))
The structural unit (VIII) can be contained in the polymer component (A) for the purpose of adjusting the glass transition temperature of the polymer, etc. The monomer constituting the structural unit (VIII) is preferably a methacrylate compound in which the alkyl group bonded to the ester group has 1 to 10 carbon atoms, and examples thereof include acrylic acid alkyl ester compounds such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl acrylate, tert-butyl acrylate, and 2-ethylhexyl acrylate.

When polymer component (A) contains the structural unit (VIII), the content of the structural unit (VIII) (the total content when multiple types are contained) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on all structural units constituting polymer component (A). The content is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

(Structural Unit (IX))
The structural unit (IX) is a structural unit derived from an unsaturated monomer having an epoxy group, and does not correspond to the structural unit (II). Specific examples of the structural unit (IX) include at least one selected from the group consisting of the structural unit represented by the following formula (5-1) and the structural unit represented by the following formula (5-2).

(In formula (5-1) and formula (5-2),
^R20 is a group having an oxiranyl group or an oxetanyl group (excluding an alicyclic epoxy group).
R ^A1 is a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group.
^L3 is a single bond or a divalent linking group.

In the above formulas (5-1) and (5-2), examples of R ²⁰ include an oxiranyl group, an oxetanyl group, and a 3-ethyloxetanyl group.

Examples of the divalent linking group for ^L3 include a methylene group, an ethylene group, an alkanediyl group such as a 1,3-propanediyl group, and a divalent group in which any methylene group of an alkanediyl group is replaced with --O--.

Specific examples of monomers having an epoxy group include glycidyl (meth)acrylate, (3-methyloxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl) (meth)acrylate, (oxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, etc.

When polymer component (A) contains the structural unit (IX), the content of the structural unit (IX) (the total content when multiple types are contained) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on all structural units constituting polymer component (A). The content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less.

(Other structural units)
Examples of the other structural units include, in addition to the above, unsaturated dicarboxylic acid dialkyl ester compounds such as diethyl itaconate, unsaturated dicarboxylic acid anhydrides such as phthalic anhydride, conjugated diene compounds such as 1,3-butadiene and isoprene, nitrogen-containing vinyl compounds such as (meth)acrylonitrile, (meth)acrylamide, N-vinyl alkylamide and N-vinyl pyrrolidone, and structural units derived from monomers such as vinyl chloride, vinylidene chloride and vinyl acetate. In the polymer component (A), the content ratio of the other structural units is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, based on the total structural units constituting the polymer component (A).

The content ratio of each structural unit is usually equivalent to the ratio of the monomers used in the production of polymer component (A).

In the polymer component (A), the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 2,000 or more. Mw of 2,000 or more is preferable in that a cured film having sufficiently high chemical resistance and good developability can be obtained. Mw is more preferably 5,000 or more, even more preferably 6,000 or more, and particularly preferably 8,000 or more. In addition, from the viewpoint of improving film-forming properties, Mw is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 18,000 or less, and particularly preferably 15,000 or less.

In the polymer component (A), the molecular weight distribution (Mw/Mn), which is the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.7 or less. When the polymer component (A) is composed of two or more polymers, it is preferable that each of the polymers satisfy the above-mentioned ranges of Mw and Mw/Mn.

The content of polymer component (A) is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total amount of solids contained in the radiation-sensitive composition. The content of polymer component (A) is preferably 95% by mass or less, more preferably 90% by mass or less, based on the total amount of solids contained in the radiation-sensitive composition. By setting the content of polymer component (A) in the above range, it is advantageous in that a cured film having sufficiently high chemical resistance and good developability and transparency can be obtained.

The polymer component (A) can be produced, for example, by using an unsaturated monomer capable of introducing each of the structural units described above in a suitable solvent in the presence of a polymerization initiator, according to a known method such as radical polymerization. Specifically, examples of the polymerization initiator used include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(isobutyric acid) dimethyl. The proportion of the polymerization initiator used is preferably 0.01 to 30 parts by mass relative to 100 parts by mass of the total amount of the monomers used in the reaction. Examples of the polymerization solvent include alcohols, ethers, ketones, esters, and hydrocarbons.

In the above polymerization reaction, the reaction temperature is usually 30°C to 180°C. The reaction time varies depending on the type of initiator and monomer and the reaction temperature, but is usually 0.5 to 10 hours. The amount of organic solvent used is preferably such that the total amount of monomers used in the reaction is 0.1 to 60 mass% of the total amount of the reaction solution. The polymer obtained by the polymerization reaction can be isolated using known isolation methods, such as a method of pouring the reaction solution into a large amount of poor solvent and drying the resulting precipitate under reduced pressure, or a method of distilling the reaction solution under reduced pressure using an evaporator.

<Quinonediazide compound (B)>
The quinone diazide compound (B) is a radiation-sensitive acid generator that generates a carboxylic acid upon irradiation with radiation. As the quinone diazide compound, it is preferable to use a condensation product of a phenolic compound or an alcoholic compound (hereinafter also referred to as a "mother nucleus") with a 1,2-naphthoquinone diazide sulfonic acid halide.

Examples of the mother nucleus include trihydroxybenzophenone, tetrahydroxybenzophenone, pentahydroxybenzophenone, hexahydroxybenzophenone, (polyhydroxyphenyl)alkane, and other mother nuclei. Specific examples of these include trihydroxybenzophenones such as 2,3,4-trihydroxybenzophenone and 2,4,6-trihydroxybenzophenone; tetrahydroxybenzophenones such as 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,3'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,2'-tetrahydroxy-4'-methylbenzophenone, 2,3,4,4'-tetrahydro ... hydroxy-3'-methoxybenzophenone, etc.; pentahydroxybenzophenones, for example, 2,3,4,2',6'-pentahydroxybenzophenone, etc.; hexahydroxybenzophenones, for example, 2,4,6,3',4',5'-hexahydroxybenzophenone, 3,4,5,3',4',5'-hexahydroxybenzophenone, etc.; (polyhydroxyphenyl)alkanes, for example, bis(2,4-dihydroxyphenyl)methane, bis(p-hydroxyphenyl)methane , tri(p-hydroxyphenyl)methane, 1,1,1-tri(p-hydroxyphenyl)ethane, bis(2,3,4-trihydroxyphenyl)methane, 2,2-bis(2,3,4-trihydroxyphenyl)propane, 1,1,3-tris(2,5-dimethyl-4-hydroxyphenyl)-3-phenylpropane, 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol, bis(2,5-dimethyl-4-hydroxyphenyl)- 2-hydroxyphenylmethane, 3,3,3',3'-tetramethyl-1,1'-spirobiindene-5,6,7,5',6',7'-hexanol, 2,2,4-trimethyl-7,2',4'-trihydroxyflavan, etc.; other mother nuclei include, for example, 2-methyl-2-(2,4-dihydroxyphenyl)-4-(4-hydroxyphenyl)-7-hydroxychroman, 2-[bis{(5-isopropyl-4-hydroxy-2-methyl)phenyl}methyl], etc.

Of these, the preferred mother nuclei are 2,3,4,4'-tetrahydroxybenzophenone, 1,1,1-tri(p-hydroxyphenyl)methane, 1,1,1-tri(p-hydroxyphenyl)ethane, and 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol.

As the 1,2-naphthoquinone diazide sulfonic acid halide, 1,2-naphthoquinone diazide sulfonic acid chloride is preferred. Specific examples include 1,2-naphthoquinone diazide-4-sulfonic acid chloride, 1,2-naphthoquinone diazide-5-sulfonic acid chloride, and the like. Of these, as the 1,2-naphthoquinone diazide sulfonic acid halide, 1,2-naphthoquinone diazide-5-sulfonic acid chloride is preferably used.

In the condensation reaction to obtain the above condensation product, the ratio of the mother nucleus to the 1,2-naphthoquinone diazide sulfonic acid halide is preferably such that the amount of 1,2-naphthoquinone diazide sulfonic acid halide used is equivalent to 30 to 85 mol %, more preferably 50 to 70 mol %, of the number of OH groups in the mother nucleus. The above condensation reaction can be carried out according to a known method. A 1,2-quinone diazide compound is obtained by the condensation reaction of the mother nucleus with the 1,2-naphthoquinone diazide sulfonic acid halide.

The content of the quinone diazide compound (B) in the radiation-sensitive composition is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the polymer component (A). The content of the quinone diazide compound (B) is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the polymer component (A). When the content of the quinone diazide compound (B) is 2 parts by mass or more, sufficient acid is generated by irradiation with radiation, and the difference in solubility between the irradiated and unirradiated parts in an alkaline solution can be sufficiently increased, which is preferable. This allows good patterning to be performed. In addition, the amount of acid involved in the reaction with the polymer component (A) can be increased, which is preferable because chemical resistance can be sufficiently ensured. On the other hand, when the content of the quinone diazide compound (B) is 100 parts by mass or less, the amount of unreacted quinone diazide compound (B) can be sufficiently reduced, and a decrease in developability due to the remaining quinone diazide compound (B) can be suppressed, which is preferable.

<Solvent (C)>
The radiation-sensitive composition of the present disclosure is a liquid composition in which the polymer component (A), the quinone diazide compound (B), and other components blended as necessary are dissolved or dispersed, preferably in a solvent (C). The solvent used is preferably an organic solvent that dissolves each of the components blended in the radiation-sensitive composition and does not react with each of the components.

The solvent (C) is not particularly limited, and examples thereof include alcohol-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, and amide-based solvents. Solvent (C) may be used alone or in combination of two or more kinds.

Examples of alcohol-based solvents include alkyl alcohols such as methanol, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, t-butyl alcohol, 1-hexanol, 1-octanol, 1-nonanol, 1-dodecanol, 1-methoxy-2-propanol, and diacetone alcohol; and aromatic alcohols such as benzyl alcohol.

Examples of ether solvents include ethylene glycol monoalkyl ethers such as diethylene glycol methyl ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether; diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether and diethylene glycol ethyl methyl ether; and dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and dipropylene glycol monobutyl ether.

Examples of ester-based solvents include carboxylic acid esters such as ethyl acetate, i-propyl acetate, n-butyl acetate, amyl acetate, ethyl lactate, methyl 3-methoxypropionate, and ethyl 3-ethoxypropionate; polyhydric alcohol carboxylate-based solvents such as propylene glycol diacetate; and polyhydric alcohol partial ether carboxylate-based solvents such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate.

Examples of ketone solvents include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and cycloheptanone.

Among these, ether-based solvents and ester-based solvents are preferred, ester-based solvents are more preferred, and polyhydric alcohol partial ether carboxylate-based solvents are even more preferred. Among the ether-based solvents and ester-based solvents, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, and methyl 3-methoxypropionate are preferred.

The content of the solvent (C) in the composition is not particularly limited, but it is preferable that the solid content (components other than the solvent (C)) of the composition is adjusted to be within the following range. The lower limit of the solid content concentration in the composition is preferably 5% by mass, more preferably 8% by mass, and even more preferably 15% by mass. On the other hand, the upper limit of the solid content concentration is preferably 60% by mass, more preferably 40% by mass, and even more preferably 30% by mass. When the solid content concentration of the radiation-sensitive composition is 5% by mass or more, it is preferable that the thickness of the coating film can be sufficiently secured when the radiation-sensitive composition is applied onto a substrate. In addition, when the solid content concentration is 60% by mass or less, it is preferable that the thickness of the coating film is not too large, and the viscosity of the radiation-sensitive composition can be appropriately increased, and good coating properties can be secured.

<Solvent (C1)>
In addition to the solvent (C), the composition of the present disclosure may include a solvent (C1) having a boiling point of 180° C. or more and a hydrogen bond term δH of the Hansen solubility parameter of 3.0 to 13.0. Here, the Hansen solubility parameter (HSP value) is an index that takes into account the polarity of physical properties by dividing the Hildebrand solubility parameter (SP value) into three components, the dispersion force term δD, the polarity term δP, and the hydrogen bond term δH, and has the relationship "SP ² = δD ² + δP ² + δH ² ". In this specification, the Hansen solubility parameter is a value calculated using the calculation software HSPiP ver. 5. The boiling point of the solvent is a value at 1 atmosphere.

The type of solvent (C1) is not particularly limited as long as it has a boiling point of 180°C or higher and a hydrogen bond term δH of the HSP value of 3.0 to 13.0. Solvent (C1) is preferably at least one selected from the group consisting of alcohols, carbonates, ethers, and esters. Solvent (C1) may be a compound having a chain structure or a compound having a cyclic structure.

Specific examples of the solvent (C1) include dihydroterpineol (δH = 6.69, boiling point = 210°C), (S)-4-methyl-1,3-dioxolan-2-one (δH = 7.35, boiling point = 242°C), diethylene glycol monobutyl ether (δH = 10.46, boiling point = 231°C), dipropylene glycol methyl ether acetate (δH = 5.78, boiling point = 213°C), triethylene glycol monobutyl ether (δH = 9.14, boiling point = 278°C), propyl lactate (δH = 11.7, boiling point = 188°C), and benzyl alcohol (δH = 12.5, boiling point 205°C).

When solvent (C) contains solvent (C1), the content of solvent (C1) is preferably 10% by mass or less based on the total amount of the solvent.

<Other ingredients>
The radiation-sensitive composition of the present disclosure may further contain components other than the above-mentioned polymer component (A), quinone diazide compound (B), and solvent (C) (hereinafter also referred to as "other components"). Examples of other components include reaction initiators (photoradical polymerization initiators, photocationic polymerization initiators, etc.), polyfunctional polymerizable compounds (polyfunctional (meth)acrylates, etc.), adhesion aids (functional silane coupling agents, etc.), surfactants (fluorine-based surfactants, silicone-based surfactants (silane-based surfactants), nonionic surfactants, etc.), polymerization inhibitors, antioxidants, chain transfer agents, etc. The blending ratio of these components is appropriately selected according to each component within a range that does not impair the effects of the present disclosure. In addition, the radiation-sensitive composition of the present disclosure may contain a silane-based surfactant, but it is preferable that it does not contain a silane-based surfactant.

The solids concentration of the radiation-sensitive composition of the present disclosure (the ratio of the total mass of the components other than the solvent (C) in the radiation-sensitive composition to the total mass of the radiation-sensitive composition) is appropriately selected taking into consideration the viscosity, volatility, etc.

(Dielectric constant of cured film obtained from radiation-sensitive composition)
By curing this composition, a cured film with a sufficiently low dielectric constant can be obtained. Specifically, the dielectric constant of the obtained cured film at a frequency of 10 kHz is preferably 3.4 or less, more preferably less than 3.1. For details of the method for measuring the dielectric constant of the cured film, follow the method described in the examples below.

The radiation-sensitive composition of the present disclosure uses a quinone diazide compound (B) as a radiation-sensitive acid generator together with a polymer component (A) containing structural units (I) to (III), thereby making it possible to increase the glass transition temperature of the polymer while maintaining high radiation sensitivity, and as a result, it is possible to suppress melt flow, obtain a good pattern shape, and also to sufficiently reduce the relative dielectric constant, thereby forming a cured film with excellent chemical resistance. Such a radiation-sensitive composition of the present disclosure is useful as a composition for forming a planarizing film or an interlayer insulating film for display elements.

<Production method of cured film>
The cured film of the present disclosure is formed from the radiation-sensitive composition prepared as described above. The radiation-sensitive composition of the present disclosure has high radiation sensitivity, can suppress melt flow due to heat after patterning, and has good relative dielectric constant and chemical resistance.

In producing a cured film, the above-mentioned radiation-sensitive composition can be used to form a positive cured film by irradiation with radiation (ultraviolet rays, far-ultraviolet rays, visible light, etc.). The cured film of the present disclosure can be produced, for example, by a method including the following (Step 1) to (Step 5).
(Step 1) A step of applying a radiation-sensitive composition onto a substrate to form a coating film.
(Step 2) A step of removing the solvent from the coating film.
(Step 3) A step of irradiating the coating film from which the solvent has been removed with radiation.
(Step 4) A step of developing the coating film that has been irradiated with radiation.
(Step 5) A step of thermally curing the developed coating film.
Each step will be described in detail below.

<Steps 1 and 2: Paint film formation step>
In this step, the radiation-sensitive composition is applied to a surface on which a coating film is to be formed (hereinafter also referred to as "film-forming surface"), and the solvent is preferably removed by a heat treatment (pre-bake) to form a coating film on the film-forming surface. The material of the film-forming surface is not particularly limited. For example, when a planarizing film is formed using the radiation-sensitive composition, the radiation-sensitive composition is applied to a substrate provided with switching elements such as TFTs to form a coating film. As the substrate, for example, a glass substrate or a resin substrate is used.

Examples of methods for applying the radiation-sensitive composition include spraying, roll coating, spin coating, slit die coating, bar coating, and inkjet. Of these, spin coating, slit die coating, and bar coating are preferred. Pre-baking conditions vary depending on the types and content ratios of each component in the radiation-sensitive composition, but are, for example, 60 to 130°C and 0.5 to 10 minutes. The thickness of the coating film formed (i.e., the film thickness after pre-baking) is preferably 1 to 12 μm.

<Step 3: Exposure Step>
In this step, at least a part of the coating film formed in steps 1 and 2 above is irradiated with radiation. At this time, by irradiating the coating film with radiation through a mask having a predetermined pattern, a cured film having a pattern (for example, an interlayer insulating film) can be formed. Examples of radiation include charged particle beams such as ultraviolet rays, far ultraviolet rays, visible rays, X-rays, and electron beams. Among these, ultraviolet rays are preferred, and examples of such beams include g-rays (wavelength 436 nm) and i-rays (wavelength 365 nm). The exposure dose of radiation is preferably 0.1 to 20,000 J/ ^m2 .

<Step 4: Development step>
In this step, the coating film irradiated in step 3 is developed. Specifically, the coating film irradiated in step 3 is developed with a developer to remove the irradiated portion, thereby performing positive development. Examples of the developer include an aqueous solution of an alkali (basic compound). Examples of the alkali include sodium hydroxide, tetramethylammonium hydroxide, and the alkalis exemplified in paragraph [0127] of JP-A-2016-145913. From the viewpoint of obtaining appropriate developability, the alkali concentration in the aqueous alkali solution is preferably 0.1 to 5.0% by mass. Examples of the development method include a suitable method such as a puddle method, a dipping method, a swing immersion method, and a shower method. The development time varies depending on the composition of the composition, but is, for example, 30 to 120 seconds. After the development step, it is preferable to perform a rinse treatment by washing with running water on the patterned coating film.

<Step 5: Heating step>
In this step, the coating film developed in step 4 is heated (post-baked). This allows the film curing reaction to proceed, resulting in a cured film that exhibits good chemical resistance. Post-baking can be performed using a heating device such as an oven or a hot plate. Regarding post-baking conditions, the heating temperature is, for example, 120 to 250° C. The heating time is, for example, 5 to 40 minutes when the heat treatment is performed on a hot plate, and 10 to 80 minutes when the heat treatment is performed in an oven. In this manner, a cured film having a desired pattern can be formed on a substrate.

A post-exposure step may be further included between step 4 and step 5. By irradiating the coating film after development with radiation, a cured film having excellent melt flow resistance and transparency in a heating step can be formed. Examples of radiation include charged particle beams such as ultraviolet light, far ultraviolet light, visible light, X-rays, and electron beams. Among these, ultraviolet light is preferred, and examples thereof include g-rays (wavelength 436 nm) and i-rays (wavelength 365 nm). The exposure dose of radiation is preferably 0.1 to 20,000 J/ ^m2 .

≪Cured film≫
The cured film of the present disclosure is formed using the radiation-sensitive composition. The radiation-sensitive composition of the present disclosure has high radiation sensitivity, can suppress melt flow due to heat after patterning, and has good dielectric constant and chemical resistance. Therefore, the cured film is useful as an insulating film for an organic EL element. Specifically, the cured film can be used as a planarizing film for planarizing surface irregularities caused by thin film transistors (TFTs) and the like, an interlayer insulating film for insulating between wirings, a partition wall and a bank defining an area in which a light-emitting layer is formed, a protective film for protecting TFTs and the like, a spacer, an adhesive layer for color filters, and the like in an organic EL element. In this specification, the "partition wall" refers to a member used for color separation such as a color filter or a color conversion layer using quantum dots, and the "bank" refers to a member for separating light-emitting layers. Among these, the cured film of the present disclosure is particularly useful as an interlayer insulating film or a planarizing film.

<Display element>
A display element according to the present disclosure includes a cured film formed using the radiation-sensitive composition. Examples of the display element include a liquid crystal display element, an organic electroluminescence (EL) display element, and a micro LED display element.

The display element of the present disclosure can be effectively applied to a variety of applications, and can be used as various display devices such as watches, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Note that "parts" and "%" in the examples and comparative examples are based on mass unless otherwise specified.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
The Mw and Mn of the polymer were measured by the following method.
Measurement method: gel permeation chromatography (GPC) method Apparatus: GPC-101 manufactured by Showa Denko K.K.
GPC column: Shimadzu GLC's GPC-KF-801, GPC-KF-802, GPC-KF-803 and GPC-KF-804 Mobile phase: Tetrahydrofuran Column temperature: 40°C
Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
・Detector: Differential refractometer ・Standard material: Monodisperse polystyrene

[Monomer]
The monomers used in the synthesis of the copolymer are as follows:
(Structural Unit (I))
MA: methacrylic acid PIPE: p-isopropenylphenol MI: maleimide (structural unit (II))
ECHMA: 3,4-epoxycyclohexylmethyl methacrylate ETCDA: A mixture of 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decan-9-yl acrylate and 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decan-8-yl acrylate [50:50 (molar ratio)]
(Structural unit (III))
CHMA: cyclohexyl methacrylate CHA: cyclohexyl acrylate DCM: dicyclopentanyl methacrylate DCA: dicyclopentanyl acrylate IBA: isobornyl acrylate (structural unit (IV))
MPTMS: 3-methacryloxypropyltrimethoxysilane MPTES: 3-methacryloxypropyltriethoxysilane (structural units other than structural units (I) to (IV))
CHMI: N-cyclohexylmaleimide GMA: glycidyl methacrylate MMA: methyl methacrylate HEMA: 2-hydroxyethyl methacrylate

Unless otherwise specified, all parts are by weight.

<Synthesis of Polymer (A)>
Synthesis Example 1: Synthesis of polymer (A-1) 13 parts of 2,2'-azobis(isobutyrate)dimethyl and 200 parts of diethylene glycol methyl ethyl ether were charged into a flask equipped with a cooling tube and a stirrer. Subsequently, 13 parts of methacrylic acid, 15 parts of 3,4-epoxycyclohexylmethyl methacrylate, 15 parts of cyclohexyl methacrylate, and 57 parts of methyl methacrylate were charged, and the mixture was substituted with nitrogen. The temperature of the solution was raised to 80°C while gently stirring, and this temperature was maintained for 5 hours to obtain a polymer solution containing polymer (A-1). The solid content concentration of this polymer solution was 35.3% by mass, and the Mw of polymer (A-1) was 11,000 and the molecular weight distribution (Mw/Mn) was 2.4.

[Synthesis Examples 2 to 16, Comparative Synthesis Examples 1 to 6]
Synthesis of polymers (A-2) to (A-16) and polymers (A'-1 to A'-6) Polymer solutions containing polymers (A-2) to (A-16), (A'-1) to (A'-3), and (A'-5) to (A'-6) having the same solid content concentration, molecular weight, and molecular weight distribution as polymer (A-1) were obtained in the same manner as in Synthesis Example 1, except that the components of the types and amounts (parts by mass) shown in Table 1 were used. Polymer (A'-4) was synthesized according to Synthesis Example 1 in paragraph [0133] of JP-A-2007-156471. In addition, in the following Tables 1 and 2, "-" indicates that the corresponding component was not used.

<Preparation of Radiation-Sensitive Composition>
The polymer (A), 1,2-quinonediazide compound (B) and solvent (C) used in the preparation of the radiation-sensitive composition are shown below.

<<Polymer (A)>>
A-1 to A-16: Polymers (A-1) to (A-16) synthesized in Synthesis Examples 1 to 16
A'-1 to A'-6: Polymers (A'-1) to (A'-6) synthesized in Comparative Synthesis Examples 1 to 6
Quinone diazide (B)
B-1: Condensate of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol (1.0 mol) and 1,2-naphthoquinone diazide-5-sulfonic acid chloride (2.0 mol) {Solvent (C)}
C-1: Diethylene glycol methyl ethyl ether (EDM)
C-2: Propylene glycol monomethyl ether (PGME)
C-3: Propylene glycol monomethyl ether acetate (PGMEA)

<Preparation of Radiation-Sensitive Composition>
[Example 1]
20 parts of quinone diazide compound (B-1) was mixed with a polymer solution containing polymer (A-1) in an amount equivalent to 100 parts (solid content) of polymer (A-1), and diethylene glycol methyl ethyl ether (EDM), propylene glycol monomethyl ether (PGME), and propylene glycol monomethyl ether acetate (PGMEA) were added so that the final solid content concentration was 20% by mass. The solvents were added so that the ratio of the solvents in the radiation-sensitive composition was EDM:PGME:PGMEA=50:25:25. The mixture was then filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive composition.

[Examples 2 to 16, Comparative Examples 1 to 6]
Radiation-sensitive compositions of Examples 2 to 16 and Comparative Examples 1 to 6 were prepared in the same manner as in Example 1, except that the types and blend amounts (parts by mass) of each component shown in Table 2 were used.

<Evaluation>
Cured films were formed from the radiation-sensitive compositions of Examples 1 to 16 and Comparative Examples 1 to 6, and the following items were evaluated by the methods described below. The evaluation results are shown in Table 3 below.

[Radiation Sensitivity]
On a 6-inch glass wafer, hexamethyldisilazane (HMDS) was applied using a spinner and heated at 60°C for 1 minute (HMDS treatment). On the wafer after the HMDS treatment, each radiation-sensitive composition prepared as described above was applied using a spinner. After that, the wafer was dried at 30 Pa for 1 second in a small reduced pressure drying device, and then prebaked at 100°C for 2 minutes to form a coating film with a thickness of 3.0 μm. Next, the coating film was exposed to light through a mask having a rectangular exposure area of 10 μm x 10 μm by changing the exposure amount using an exposure machine (Canon's "MPA-600FA": using an ultra-high pressure mercury lamp). Then, the coating film was developed by a puddle method at 25°C with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide. The development time was 80 seconds. Next, the wafer was washed with running ultrapure water for 1 minute, and then dried to form a pattern on the wafer after the HMDS treatment. The entire surface of the coating film was exposed to 300 mJ/ ^cm2 , and the wafer was post-baked by heating at 230°C for 30 minutes in a clean oven to obtain a cured film. The exposure dose required to form a 10 μm x 10 μm pattern during development was examined. The smaller the exposure dose, the better the radiation sensitivity can be evaluated.
(Evaluation Criteria)
AA: less than 90 mJ/ ^cm2 A: 90 mJ/cm2 or ^more and less than 120 mJ/ ^cm2 B: 120 mJ/ ^cm2 or more and less than 150 mJ/ ^cm2 C: 150 mJ/cm2 or ^more

<Melt flow resistance>
The cross-sectional shape of the coating film pattern resolved at the above optimal exposure dose was observed with a scanning electron microscope. A tangent line was drawn to the coating film pattern at the end point where the coating film pattern contacted the substrate, and the angle between the tangent line and the substrate surface was calculated. The higher the angle, the better the melt flow resistance was evaluated to be maintained even after heating at 230°C.
(Evaluation Criteria)
AA: 70° or more A: 60° or more and less than 70° B: 40° or more and less than 60° C: Less than 40°

<Dielectric constant>
Using a spinner, the radiation-sensitive composition was applied onto a glass substrate with ITO (indium tin oxide), and then prebaked on a hot plate at 100° C. for 2 minutes to form a coating film. The rotation speed of the spinner was adjusted so that the coating film would have an average film thickness of 3.0 μm after heating at 230° C. for 30 minutes, as described below. Thereafter, development was performed at 25° C. using a 2.38% by mass tetramethylammonium hydroxide aqueous solution by a puddle method. The development time was 80 seconds. Next, the substrate was washed with running ultrapure water for 1 minute, and then dried. Using an exposure machine (Canon's "MPA-600FA": using an ultra-high pressure mercury lamp), the entire surface of the coating film was exposed to light so that the cumulative exposure amount was 300 mJ/cm ² , and the exposed substrate was heated in a clean oven at 230° C. for 30 minutes to form a cured film on the ITO substrate. Next, an aluminum electrode pattern was formed on the cured film by a vapor deposition method to prepare a sample for measuring the dielectric constant. The dielectric constant of the substrate having this electrode pattern was measured at a frequency of 10 kHz using an electrode (Yokogawa-Hewlett-Packard Company's "HP16451B") and a precision LCR meter (Yokogawa-Hewlett-Packard Company's "HP4284A").
(Evaluation Criteria)
AA: Less than 3.1 A: 3.1 or more and less than 3.4 B: 3.4 or more and less than 3.7 C: 3.7 or more

<Chemical resistance>
The cured film prepared in the above evaluation of radiation sensitivity was immersed in N-methyl-2-pyrrolidone heated to 65°C for 6 minutes, and after immersion, the coating film was washed with running ultrapure water for 5 seconds and dried. The film thickness of the cured film after treatment was measured using a stylus film thickness meter. The N-methyl-2-pyrrolidone swelling ratio (%) was calculated according to the following formula, and the chemical resistance was evaluated according to the following criteria.
Swelling rate of N-methyl-2-pyrrolidone (%)=(P/Q−1)×100
(In the formula, P represents the remaining film thickness (μm) after immersion, and Q represents the remaining film thickness (μm) before immersion.)
(Evaluation Criteria)
AA: Less than 2% A: 2% to less than 4% B: 4% to less than 6% C: 6% or more

As shown in Table 3, the radiation-sensitive compositions of Examples 1 to 16 had good practical properties such as radiation sensitivity, melt flow resistance, dielectric constant, and chemical resistance, and the various properties were well-balanced. In contrast, Comparative Examples 1 to 6 were rated "C" for one or more properties, and were inferior to Examples 1 to 16.

Claims (11)

A polymer component (A),
A quinone diazide compound (B),
A solvent (C);
A radiation-sensitive composition comprising:
The polymer component (A) is
At least one structural unit (I) selected from the group consisting of structural units having an acid group and structural units derived from maleimide;
A structural unit (II) containing an alicyclic epoxy group;
A structural unit (III) derived from a (meth)acrylate having an alicyclic structure (excluding the structural unit (II)),
in the same or different polymers,
The structural unit (II) accounts for 10 mass% or more of all structural units constituting the polymer component (A),
the structural unit (III) accounts for 10 mass % or more of all structural units constituting the polymer component (A); 2. The radiation-sensitive composition according to claim 1, wherein the structural unit (II) is represented by the following formula (II-1), formula (II-2), or formula (II-3):
(Formula (II-1) to formula (II-3),
Each R ¹ is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
Each ^L1 is independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.
n is an integer from 1 to 5.
k1 is 0 or 1.
Each X ¹ is independently a hydroxy group, a halogen atom, a cyano group, a nitro group, an alkyl group, or an alkoxy group.
a1 is an integer of 0 to 3. When a1 is 2 or more, the multiple ^X1s are the same or different. The radiation-sensitive composition according to claim 1, wherein the alicyclic structure is a monocyclic alicyclic structure. The radiation-sensitive composition according to claim 1, wherein the (meth)acrylate having an alicyclic structure is cyclohexyl (meth)acrylate. The radiation-sensitive composition according to claim 1, wherein the polymer component (A) further contains a structural unit (IV) having an alkoxysilyl group. The radiation-sensitive composition according to claim 1, wherein the cured film formed by curing the radiation-sensitive composition has a dielectric constant of less than 3.4 at 10 kHz. A step of applying the radiation-sensitive composition according to any one of claims 1 to 6 onto a substrate;
removing the solvent from the applied radiation-sensitive composition;
a step of exposing the radiation-sensitive composition from which the solvent has been removed to radiation;
developing the radiation-exposed radiation-sensitive composition;
thermally curing the developed radiation-sensitive composition;
The method for producing a cured film comprising the steps of: A cured film formed using the radiation-sensitive composition according to any one of claims 1 to 6. The cured film according to claim 8, which is an interlayer insulating film or a planarizing film. A display device comprising the cured film according to claim 9. The display element according to claim 10, which is for an organic electroluminescence (EL) display.