JP7477443B2 - CURABLE RESIN COMPOSITION, CURED PRODUCT THEREOF, METHOD FOR PRODUCING CURED FILM, AND METHOD FOR PRODUCING MICRO-LENS - Google Patents

Description

The present invention relates to a curable resin composition, a cured product thereof, a method for producing a cured film using the curable resin composition, and a method for producing a microlens using the curable resin composition.

Solid-state imaging elements have traditionally been used in cameras, video cameras, and the like. These solid-state imaging elements include charge-coupled device (CCD) image sensors and complementary metal-oxide semiconductor (CMOS) image sensors. Image sensors are equipped with minute focusing lenses (hereafter referred to as microlenses) to improve the light collection rate.

The etch-back method is known as one method for producing microlenses for CCD or CMOS image sensors (Patent Documents 1 and 2). That is, a resist pattern is formed on a resin layer for microlenses formed on a color filter, and the resist pattern is reflowed by heat treatment to form a lens pattern. The lens pattern thus formed is used as an etching mask to etch back the underlying resin layer for microlenses, and the shape of the lens pattern is transferred to the resin layer for microlenses to produce a microlens.

Japanese Patent Application Laid-Open No. 1-10666 Japanese Patent Application Laid-Open No. 6-112459

The lower resin layer for microlenses is formed by forming a coating film made of a curable resin composition on the color filter and curing the coating film. Generally, in order to impart curability to the resin in the curable resin composition, a structural unit having an epoxy group that causes curing by heat is widely used as a structural unit in the resin. However, the inventors' investigations revealed that the curability is insufficient when only a structural unit having an epoxy group is used.

The curing of the structural unit having an epoxy group can be accelerated by using an acid. However, the inventors have found that sufficient curing cannot be achieved on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone pair of electrons, for example, on a green color filter containing phthalocyanine, because the nitrogen-containing compound or phthalocyanine deactivates the acid.

In order to improve the curability on a layer containing a nitrogen-containing compound that contains a nitrogen atom with a lone electron pair, the present inventors increased the amount of structural units having an acid group such as a carboxy group in a resin having structural units having an epoxy group. Although the curability was improved, it was found that the curable resin composition had a short pot life due to high reactivity between the acid group and the epoxy group even during storage.

The present invention has been made in consideration of such conventional circumstances, and aims to provide a curable resin composition that exhibits excellent curability even on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone electron pair and has a long pot life, a cured product thereof, a method for producing a cured film using the curable resin composition, and a method for producing a microlens using the curable resin composition.

The present inventors have found that the above problems can be solved by having a resin contained in a curable resin composition that has at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and a structural unit having an epoxy group, and have completed the present invention.

A first aspect of the present invention is a curable resin composition containing a resin (A), a thermal acid generator (B), and a solvent (S),
The resin (A) has at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected with an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected with an acid dissociable group, and a structural unit having an epoxy group.

The second aspect of the present invention is a cured product of the curable resin composition according to the first aspect.

A third aspect of the present invention is
forming a coating film made of the curable resin composition according to the first aspect on at least a part of a main surface of a nitrogen-containing compound-containing layer;
heating the coating film to form a cured film;
The present invention relates to a method for producing a cured film, comprising the steps of:

A fourth aspect of the present invention is a method for manufacturing a microlens, comprising the steps of:
The manufacturing method includes:
Forming a coating film made of the curable resin composition according to the first aspect on a substrate;
heating the coating film to form a cured film;
forming a mask on the cured film having a shape corresponding to the shape of a lens to be formed;
forming a lens having a shape transferred from the mask by etching the cured film together with the mask;
including.

According to the present invention, it is possible to provide a curable resin composition that exhibits excellent curability even on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone pair of electrons and has a long pot life, a cured product thereof, a method for producing a cured film using the curable resin composition, and a method for producing a microlens using the curable resin composition.

<Curable resin composition>
The curable resin composition according to the present invention contains a resin (A), a thermal acid generator (B), and a solvent (S), and the resin (A) contains at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and a structural unit having an epoxy group. The curable resin composition according to the present invention exhibits excellent curability even on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone electron pair, and has a long pot life.

The curable resin composition according to the present invention can be suitably used to produce a permanent film on at least a part of the main surface of a nitrogen-containing compound-containing layer. Here, the nitrogen-containing compound-containing layer contains a nitrogen-containing compound that contains a nitrogen atom having a lone electron pair. The curable resin composition according to the present invention can also be suitably used to form a microlens.

[Nitrogen-containing compound-containing layer]
The nitrogen-containing compound-containing layer is a layer containing a nitrogen-containing compound containing a nitrogen atom having a lone electron pair. In the nitrogen-containing compound layer, the base material component which is a matrix for dispersing the nitrogen-containing compound is not particularly limited as long as it does not impair the object of the present invention.
Examples of the base material component include various resins and cured products of various curable compounds.

Specific examples of resins that can be used as the base component include polyacetal resin, polyamide resin, polycarbonate resin, polyester resin (polybutylene terephthalate, polyethylene terephthalate, polyarylate, etc.), FR-AS resin, FR-ABS resin, AS resin, ABS resin, polyphenylene oxide resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyetheretherketone resin, fluorine-based resin, polyimide resin, polyamideimide resin, polyamide bismaleimide resin, polyetherimide resin, polybenzoxazole resin, polybenzothiazole resin, polybenzimidazole resin, silicone resin, BT resin, polymethylpentene, ultra-high molecular weight polyethylene, FR-polypropylene, (meth)acrylic resin (polymethyl methacrylate, etc.), cardo resin, and polystyrene. Two or more of these resins may be used in combination.

Examples of curable compounds that provide a cured product as a base material component include polyfunctional epoxy compounds having two or more functional groups, and polyfunctional oxetane compounds having two or more functional groups. Polyfunctional epoxy compounds and polyfunctional oxetane compounds are cured by exposure to light and/or heating, using a curing agent or curing accelerator as necessary, to provide a cured product with excellent heat resistance and mechanical properties.

The thickness of the nitrogen-containing compound-containing layer is not particularly limited. Typically, the thickness of the nitrogen-containing compound-containing layer is, for example, 0.1 μm or more and 10 μm or less, preferably 0.2 μm or more and 5 μm or less, and more preferably 0.3 μm or more and 2 μm or less.

[Nitrogen-containing compounds]
The nitrogen-containing compound is not particularly limited as long as it contains a nitrogen atom having a lone pair of electrons. The nitrogen-containing compound containing a nitrogen atom having a lone pair of electrons may be a salt or a complex.
Hereinafter, a nitrogen-containing compound containing a nitrogen atom having a lone electron pair may be simply referred to as a "nitrogen-containing compound." In the specification and claims of this application, unless otherwise specified, the term "nitrogen-containing compound" refers to a nitrogen-containing compound containing a nitrogen atom having a lone electron pair.

The curable resin composition according to the present invention is particularly effective when the lone electron pair of the nitrogen atom in the nitrogen-containing compound is not delocalized within the molecule of the nitrogen-containing compound due to conjugation. This is because when the nitrogen-containing compound-containing layer contains such a nitrogen-containing compound, the problem of poor curing of the curable resin composition becomes more pronounced.

Examples of nitrogen-containing compounds that are likely to cause poor curing of the curable resin composition include amines that do not have an aromatic group bonded to the nitrogen atom, imines that do not have an aromatic group bonded to the nitrogen atom, and aromatic nitrogen-containing heterocyclic compounds in which a lone electron pair is not incorporated in the aromatic ring system.

In the above-mentioned nitrogen-containing compounds, the nitrogen atom having a lone pair of electrons often constitutes a so-called chromophore or auxochrome. In various laminates, a colored layer containing a dye compound having a nitrogen atom having a lone pair of electrons is often formed.
Typical examples of the nitrogen-containing compound that is a dye compound include phthalocyanine pigments, dioxazine pigments, etc. The phthalocyanine pigment may be, for example, a metal phthalocyanine complex such as copper phthalocyanine.

When the nitrogen-containing compound is a dye compound, the nitrogen-containing compound-containing layer is colored. Such a colored nitrogen-containing compound-containing layer is preferably a color filter used in various types of image display panels, CMOS image sensors, etc.
The hue of the color filter is not particularly limited. When the nitrogen-containing compound-containing layer is a color filter, the color filter may typically be a green color filter, a blue color filter, or a red color filter.

The content of the nitrogen-containing compound in the nitrogen-containing compound-containing layer is not particularly limited. The content of the nitrogen-containing compound in the nitrogen-containing compound-containing layer is typically 1% by mass or more and 80% by mass or less, preferably 5% by mass or more and 75% by mass or less, and more preferably 40% by mass or more and 70% by mass or less, relative to the mass of the nitrogen-containing compound-containing layer.

[Resin (A)]
The resin (A) has at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and a structural unit having an epoxy group. During storage of the curable resin composition, the phenolic hydroxyl group or carboxyl group in the resin (A) is protected by an acid dissociable group, so that reactivity with the epoxy group is suppressed, and the pot life of the curable resin composition is likely to be extended. When the curable resin composition is heated, the acid dissociable group is released from the resin (A) by the acid generated from the thermal acid generator (B), and the generated phenolic hydroxyl group or carboxyl group reacts with the epoxy group, so that the curable resin composition shows excellent curability. The resin (A) can be used alone or in combination of two or more kinds.

Resin (A) may include a copolymer of at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and a structural unit having an epoxy group. In addition, when two or more types of resin (A) are used in combination, resin (A) may include a combination of a polymer having at least one of a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and having no structural unit having an epoxy group, and a polymer having a structural unit having an epoxy group and having neither a structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group nor a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group.

A structural unit having a chemical structure in which a phenolic hydroxyl group is protected with an acid dissociable group means a chemical structure in which the hydrogen atom of the phenolic hydroxyl group is substituted with an acid dissociable group. Examples of structural units having a chemical structure in which a phenolic hydroxyl group is protected with an acid dissociable group include structural units represented by the following general formula (a2-1).

（式中、Ｒ^ａ３は独立に水素原子、アルキル基、ハロゲン原子、又はハロゲン原子で置換されたアルキル基を示し、Ｒ^ａ５は独立にアルキル基を示し、Ｒ^ａ４は酸解離性基を示し、ｒは独立に１～５の整数を示し、ｓ及びｔは独立に０～４の整数を示し、但し、ｒ＋ｓ＋ｔは独立に１～５の整数である。）

(In the formula, R ^a3 independently represents a hydrogen atom, an alkyl group, a halogen atom, or an alkyl group substituted with a halogen atom; R ^a5 independently represents an alkyl group; R ^a4 independently represents an acid dissociable group; r independently represents an integer of 1 to 5; s and t independently represent integers of 0 to 4; and r+s+t independently represents an integer of 1 to 5.)

The alkyl group represented by R ^a3 is, for example, an alkyl group having 1 to 5 carbon atoms, preferably a linear or branched alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Industrially, a methyl group is preferred. Examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferred. The alkyl group substituted with a halogen atom is an alkyl group having 1 to 5 carbon atoms, in which some or all of the hydrogen atoms are substituted with halogen atoms, and it is preferred that all of the hydrogen atoms are substituted with halogen atoms. The alkyl group substituted with a halogen atom is preferably a linear or branched alkyl group substituted with a halogen atom, and more preferably a fluorinated alkyl group such as a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, or a nonafluorobutyl group, and most preferably a trifluoromethyl group (-CF ₃ ). R ^a3 is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

Examples of the alkyl group represented by R ^a5 include alkyl groups having 1 to 5 carbon atoms, and include the same as the alkyl group represented by R ^a3 . s and t are independently integers of 0 to 4, preferably 0 or 1, and particularly preferably 0 from an industrial viewpoint. When t is 1, the substitution position of R ^a5 may be any of the o-position, m-position, and p-position, and further, when t is an integer of 1 to 4, any substitution position can be combined. r represents an integer of 1 to 5, preferably an integer of 1 to 3, and preferably 1. When s is 1, the substitution position of the hydroxyl group may be any of the o-position, m-position, and p-position, but the p-position is preferred because it is easily available and low-cost. Further, when s is an integer of 2 to 4, any substitution position can be combined.

Examples of the acid-dissociable group represented by R ^a4 include a group represented by the following formula (a2-1-1), a group represented by the following formula (a2-1-2), a vinyloxyethyl group, a tetrahydropyranyl group, a tetrafuranyl group, or a trialkylsilyl group.

In the above formulas (a2-1-1) and (a2-1-2), R ^a6 and R ^a7 independently represent a hydrogen atom or an alkyl group, R ^a8 and R ^a10 independently represent an alkyl group or a cycloalkyl group, and R ^a9 represents a single bond or an alkylene group, provided that at least two of R ^a6 , R ^a7 , and R ^a8 may be bonded to each other to form a ring.

Examples of the alkyl group represented by R ^a6 or R ^a7 include linear or branched alkyl groups having 1 to 6 carbon atoms. Examples of the alkyl group represented by R ^a8 include linear or branched alkyl groups having 1 to 10 carbon atoms, and examples of the cycloalkyl group represented by R ^a8 include cycloalkyl groups having 3 to 10 carbon atoms. Examples of the alkylene group represented by R ^a9 include alkylene groups having 1 to 3 carbon atoms. Examples of the alkyl group represented by R ^a10 include linear or branched alkyl groups having 1 to 6 carbon atoms, and examples of the cycloalkyl group represented by R ^a10 include cycloalkyl groups having 3 to 6 carbon atoms.

The linear or branched alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like. The cycloalkyl group includes a cyclopentyl group, a cyclohexyl group, and the like. The alkylene group includes a methylene group, an ethylene group, a methylmethylene group, a propylene group, an isopropylene group, and an ethylmethylene group.

Specific examples of the acid dissociable group represented by the above formula (a2-1-1) include a methoxyethyl group, an ethoxyethyl group, an n-propoxyethyl group, an isopropoxyethyl group, an n-butoxyethyl group, an isobutoxyethyl group, a tert-butoxyethyl group, a cyclohexyloxyethyl group, a methoxypropyl group, an ethoxypropyl group, a 1-methoxy-1-methyl-ethyl group, and a 1-ethoxy-1-methylethyl group. Specific examples of the acid dissociable group represented by the above formula (a2-1-2) include a tert-butoxycarbonyl group and a tert-butoxycarbonylmethyl group. Examples of the trialkylsilyl group include a trimethylsilyl group, a tri-tert-butyldimethylsilyl group, and other groups in which the alkyl group has 1 to 6 carbon atoms.

The structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid-dissociable group can be used alone or in combination of two or more types.

Structural unit having a chemical structure in which a carboxyl group is protected with an acid dissociable group A chemical structure in which a carboxyl group is protected with an acid dissociable group means a chemical structure in which a hydrogen atom of a carboxyl group is substituted with an acid dissociable group. Examples of structural units having a chemical structure in which a carboxyl group is protected with an acid dissociable group include units represented by the following formulas (C2-3) to (C2-5).

In the above formulas (C2-3) to (C2-5), R ^c6 and R ^c10 to R ^c15 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluorine atom, or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms; R ^c7 to R ^c9 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms; R ^c8 and R ^c9 may be bonded to each other to form a hydrocarbon ring having 5 to 20 carbon atoms together with the carbon atom to which they are bonded; Y ^b represents an aliphatic cyclic group or alkyl group which may have a substituent; p represents an integer of 0 to 4; and q represents 0 or 1.

The linear or branched alkyl group may, for example, be a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, or a neopentyl group. A fluorinated alkyl group is one in which some or all of the hydrogen atoms of the alkyl group are replaced with fluorine atoms.

When R ^c8 and R ^c9 do not bond to each other to form a hydrocarbon ring, R ^c7 , R ^c8 and R ^c9 are preferably linear or branched alkyl groups having 2 to 4 carbon atoms. R ^c11 , R ^c12 , R ^c14 and R ^c15 are preferably hydrogen atoms or methyl groups.

The above R ^1c8 and R ^c9 may form an aliphatic cyclic group having 5 to 20 carbon atoms together with the carbon atom to which they are bonded. Specific examples of such aliphatic cyclic groups include groups in which one or more hydrogen atoms have been removed from polycycloalkanes such as monocycloalkanes, bicycloalkanes, tricycloalkanes, and tetracycloalkanes. Specific examples include groups in which one or more hydrogen atoms have been removed from monocycloalkanes such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane, and polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. In particular, groups in which one or more hydrogen atoms have been removed from cyclohexane and adamantane (which may further have a substituent) are preferred.

Furthermore, when the aliphatic cyclic group formed by R ^c8 and R ^c9 has a substituent on its ring skeleton, examples of the substituent include polar groups such as a hydroxyl group, a carboxyl group, a cyano group, and an oxygen atom (=O), and a linear or branched alkyl group having 1 to 4 carbon atoms. As the polar group, an oxygen atom (=O) is particularly preferable.

The above ^Yb is an aliphatic cyclic group or an alkyl group, and examples thereof include groups in which one or more hydrogen atoms have been removed from polycycloalkanes such as monocycloalkanes, bicycloalkanes, tricycloalkanes, and tetracycloalkanes. Specific examples thereof include groups in which one or more hydrogen atoms have been removed from monocycloalkanes such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane, and polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. In particular, groups in which one or more hydrogen atoms have been removed from adamantane (which may further have a substituent) are preferred.

Furthermore, when the aliphatic cyclic group of ^Yb has a substituent on its ring skeleton, examples of the substituent include polar groups such as a hydroxyl group, a carboxyl group, a cyano group, and an oxygen atom (=O), and linear or branched alkyl groups having 1 to 4 carbon atoms. As the polar group, an oxygen atom (=O) is particularly preferable.

Furthermore, when Y ^b is an alkyl group, it is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 6 to 15. Such an alkyl group is particularly preferably an alkoxyalkyl group, and examples of such an alkoxyalkyl group include a 1-methoxyethyl group, a 1-ethoxyethyl group, a 1-n-propoxyethyl group, a 1-isopropoxyethyl group, a 1-n-butoxyethyl group, a 1-isobutoxyethyl group, a 1-tert-butoxyethyl group, a 1-methoxypropyl group, a 1-ethoxypropyl group, a 1-methoxy-1-methyl-ethyl group, and a 1-ethoxy-1-methylethyl group.

Specific preferred examples of the structural unit represented by formula (C2-3) above include those represented by the following formulas (C2-3-1) to (C2-3-33).

In the above formulas (C2-3-1) to (C2-3-33), R ^c16 represents a hydrogen atom or a methyl group.

Specific preferred examples of the structural unit represented by formula (C2-4) above include those represented by the following formulas (C2-4-1) to (C2-4-25).

In the above formulas (C2-4-1) to (C2-4-25), R ^c16 represents a hydrogen atom or a methyl group.

Specific preferred examples of the structural unit represented by formula (C2-5) above include those represented by formulas (C2-5-1) to (C2-5-15) below.

In the above formulas (C2-5-1) to (C2-5-15), R ^c16 represents a hydrogen atom or a methyl group.

（式（ｂ１－１）中、Ｒ^１ｂは、水素原子又はメチル基を表し、Ｒ^２ｂは、単結合、又は炭素原子数１以上５以下のアルキレン基を表し、Ｒ^３ｂは、エポキシ基含有基を表す。 Structural Unit Having an Epoxy Group Examples of the structural unit having an epoxy group include a structural unit represented by the following formula (b1-1).

(In formula (b1-1), R ^1b represents a hydrogen atom or a methyl group, R ^2b represents a single bond or an alkylene group having 1 to 5 carbon atoms, and R ^3b represents an epoxy group-containing group.

The alkylene group represented by R ^2b may be linear or branched, and is preferably linear. Specific examples of the alkylene group include a methylene group, an ethane-1,2-diyl group, an ethane-1,1-diyl group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group. Among these groups, a methylene group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group are preferred, a methylene group, an ethane-1,2-diyl group, and a propane-1,3-diyl group are more preferred, and a methylene group is particularly preferred.

As R ^3b , an oxiran-2-yl group, a 3,4-epoxycyclohexyl group, and a 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decan-1-yl group are preferable.

The group represented by -R ^2b -R ^3b is preferably a glycidyl group (oxiran-2-ylmethyl group), a 3,4-epoxycyclohexylmethyl group, or a 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decan-1-yl group.

Other structural units The resin (A) may contain units other than the structural unit having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group, the structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and the structural unit having an epoxy group (hereinafter also referred to as "other structural units"). The type of other structural unit is not particularly limited as long as it does not impede the object of the present invention, and can be appropriately selected from units derived from various monomers having unsaturated bonds.

Examples of monomers that provide other structural units include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; methacrylic acid derivatives having a carboxyl group and an ester bond such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid, and 2-methacryloyloxyethyl hexahydrophthalic acid; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; meth ... Examples of suitable (meth)acrylic acid aryl esters include phenyl (meth)acrylate and benzyl (meth)acrylate; dicarboxylic acid diesters such as diethyl maleate and dibutyl fumarate; vinyl group-containing aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, vinyltoluene, hydroxystyrene, α-methylhydroxystyrene, and α-ethylhydroxystyrene; vinyl group-containing aliphatic compounds such as vinyl acetate; conjugated diolefins such as butadiene and isoprene; nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride; amide bond-containing polymerizable compounds such as acrylamide and methacrylamide; and the like. Among these, vinyl group-containing aromatic compounds such as styrene are preferred because they tend to improve the refractive index of the resulting cured product.

In the resin (A), the total ratio of the structural units having a chemical structure in which a phenolic hydroxyl group is protected by an acid dissociable group and the structural units having a chemical structure in which a carboxyl group is protected by an acid dissociable group is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, and even more preferably 25 to 75 mol%, based on all the structural units constituting the resin (A). When the resin (A) has other structural units, the above ratio in the resin (A) is preferably 10 to 85 mol%, more preferably 20 to 70 mol%, and even more preferably 25 to 60 mol%, based on all the structural units constituting the resin (A). When the above ratio is within the above range, the obtained curable resin composition is likely to exhibit excellent curability on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone electron pair.

In the resin (A), the ratio of the structural unit having an epoxy group is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, and even more preferably 25 to 75 mol%, based on all the structural units constituting the resin (A). When the resin (A) has other structural units, the above ratio in the resin (A) is preferably 10 to 85 mol%, more preferably 20 to 70 mol%, and even more preferably 25 to 60 mol%, based on all the structural units constituting the resin (A). When the above ratio is within the above range, the obtained curable resin composition is likely to exhibit excellent curability on a layer containing a nitrogen-containing compound that contains a nitrogen atom having a lone electron pair.

When resin (A) contains other structural units, the proportion of the other structural units in resin (A) is preferably 5 to 50 mol %, more preferably 10 to 47 mol %, and even more preferably 15 to 45 mol %, based on the total structural units constituting resin (A).

The mass average molecular weight of resin (A) is not particularly limited, but is preferably 2,000 to 50,000, and more preferably 5,000 to 40,000. When the mass average molecular weight is within the above range, the heat resistance and film strength of the resulting cured film are likely to be improved, and when dry etching is performed, dry etching can be performed satisfactorily. In this specification, the mass average molecular weight refers to the polystyrene equivalent determined by gel permeation chromatography (GPC).

[Thermal acid generator (B)]
The curable resin composition according to the present invention contains a thermal acid generator (B). By heating the curable resin composition according to the present invention, the thermal acid generator (B) in the curable resin composition decomposes to generate an acid. In this way, the acid dissociable group is eliminated from the resin (A) by the acid, and the generated phenolic hydroxyl group or carboxyl group reacts with the epoxy group, so that the curable resin composition exhibits excellent curability. As the thermal acid generator (B), for example, a thermal acid generator having a decomposition onset temperature of 120 to 200° C. can be mentioned. The thermal acid generator (B) can be used alone or in combination of two or more kinds.

The thermal acid generator (B) preferably contains a thermal acid generator that is composed of a cationic portion and an anionic portion, and the cationic portion is a cation represented by the following formula (c0-I). By using such a thermal acid generator, the acid-dissociable group is more easily eliminated from the resin (A), and therefore a phenolic hydroxyl group or a carboxyl group is more easily generated, which results in an improved curability of the curable resin composition.

（式（ｃ０－Ｉ）中、Ｒ^ｃ０１、Ｒ^ｃ０２、及びＲ^ｃ０３は、それぞれ独立に炭素原子数が１以上６以下であるアルキル基である。）

In formula (c0-I), R ^c01 , R ^c02 , and R ^c03 each independently represent an alkyl group having 1 to 6 carbon atoms.

In formula (c0-I), suitable examples of the alkyl group as R ^c01 , R ^c02 , and R ^c03 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, an n-pentyl group, and an n-hexyl group. As the alkyl group, a methyl group or an ethyl group is preferable, and a methyl group is more preferable. It is particularly preferable that R ^c01 , R ^c02 , and R ^c03 are all methyl groups.

That is, the cation represented by formula (c0-I) is preferably a cation represented by the following formula (c0-II):

Examples of counter anions to the cation represented by formula (c0-I) include AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , anions represented by the following formula (B2), and anions represented by the following formula (B3).

（式（Ｂ２）中、Ｒ^ｂ３、Ｒ^ｂ４、Ｒ^ｂ５、及びＲ^ｂ６は、それぞれ独立に、置換基を有していてもよい炭化水素基、又は置換基を有していてもよい複素環基であり、Ｒ^ｂ３、Ｒ^ｂ４、Ｒ^ｂ５、及びＲ^ｂ６のうちの少なくとも１つが置換基を有していてもよい芳香族炭化水素基である。）

(In formula (B2), R ^b3 , R ^b4 , R ^b5 , and R ^b6 are each independently a hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent, and at least one of R ^b3 , R ^b4 , R ^b5 , and R ^b6 is an aromatic hydrocarbon group which may have a substituent.)

（式（Ｂ３）中、Ｒ^ｂ７、Ｒ^ｂ８、Ｒ^ｂ９、及びＲ^ｂ１０は、それぞれ独立に、置換基を有していてもよい炭化水素基、又は置換基を有していてもよい複素環基であり、Ｒ^ｂ７、Ｒ^ｂ８、Ｒ^ｂ９、及びＲ^ｂ１０のうちの少なくとも１つが置換基を有していてもよい芳香族炭化水素基である。）

(In formula (B3), R ^b7 , R ^b8 , R ^b9 , and R ^b10 each independently represent a hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent, and at least one of R ^b7 , R ^b8 , R ^b9 , and R ^b10 is an aromatic hydrocarbon group which may have a substituent.)

The number of carbon atoms in the hydrocarbon group or heterocyclic group represented by R ^b3 to R ^b6 in formula (B2) is not particularly limited, but is preferably 1 or more and 50 or less, more preferably 1 or more and 30 or less, and particularly preferably 1 or more and 20 or less.

Specific examples of the hydrocarbon group as R ^b3 to R ^b6 include a linear or branched alkyl group, a linear or branched alkenyl group, a linear or branched alkynyl group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and an aralkyl group.
As described above, at least one of R ^b3 to R ^b6 is an aromatic group which may have a substituent, it is more preferable that three or more of R ^b3 to R ^b6 are aromatic groups which may have a substituent, and it is particularly preferable that all of R ^b3 to R ^b6 are aromatic groups which may have a substituent.

Examples of substituents that the hydrocarbon group or heterocyclic group represented by R ^b3 to R ^b6 may have include a halogenated alkyl group having from 1 to 18 carbon atoms, a halogenated aliphatic cyclic group having from 3 to 18 carbon atoms, a nitro group, a hydroxyl group, a cyano group, an alkoxy group having from 1 to 18 carbon atoms, an aryloxy group having from 6 to 14 carbon atoms, an aliphatic acyl group having from 2 to 19 carbon atoms, an aromatic acyl group having from 7 to 15 carbon atoms, an aliphatic acyloxy group having from 2 to 19 carbon atoms, an aromatic acyloxy group having from 7 to 15 carbon atoms, an alkylthio group having from 1 to 18 carbon atoms, an arylthio group having from 6 to 14 carbon atoms, an amino group in which one or two hydrogen atoms bonded to the nitrogen atom may be substituted with a hydrocarbon group having from 1 to 18 carbon atoms, and a halogen atom.
When the hydrocarbon groups represented by R ^b3 to R ^b6 are aromatic hydrocarbon groups, the aromatic hydrocarbon groups may be substituted with one or more substituents selected from the group consisting of alkyl groups having from 1 to 18 carbon atoms, alkenyl groups having from 2 to 18 carbon atoms, and alkynyl groups having from 2 to 18 carbon atoms.

When the hydrocarbon group represented by R ^b3 to R ^b6 has a substituent, the number of the substituent is not particularly limited and may be 1 or a plurality of more than 2. When the number of the substituents is a plurality, the plurality of substituents may be the same or different.

When R ^b3 to R ^b6 are each an alkyl group, preferred specific examples include straight-chain alkyl groups such as a methyl group, an ethyl group, a n-propyl group, a n-butyl group, a n-pentyl group, a n-hexyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-undecyl group, a n-dodecyl group, a n-tridecyl group, a n-tetradecyl group, a n-pentadecyl group, a n-hexadecyl group, a n-heptadecyl group, a n-octadecyl group, a n-nonadecyl group, and a n-icosyl group; and branched-chain alkyl groups such as an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a 2-ethylhexyl group, and a 1,1,3,3-tetramethylbutyl group.

When R ^b3 to R ^b6 are an alkenyl group or an alkynyl group, preferred examples include alkenyl groups and alkynyl groups corresponding to the above-mentioned groups preferred as the alkyl group.

When R ^b3 to R ^b6 are aromatic hydrocarbon groups, suitable examples include a phenyl group, an α-naphthyl group, a β-naphthyl group, a biphenyl-4-yl group, a biphenyl-3-yl group, a biphenyl-2-yl group, an anthryl group, and a phenanthryl group.

Preferred examples of R ^b3 to R ^b6 that are alicyclic hydrocarbon groups include cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclopentyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group; and bridged aliphatic cyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a pinanyl group.

When R ^b3 to R ^b6 are aralkyl groups, preferred examples thereof include a benzyl group, a phenethyl group, an α-naphthylmethyl group, a β-naphthylmethyl group, an α-naphthylethyl group, and a β-naphthylethyl group.

Preferred examples of heterocyclic groups each of R ^b3 to R ^b6 include a thienyl group, a furanyl group, a selenophenyl group, a pyranyl group, a pyrrolyl group, an oxazolyl group, a thiazolyl group, a pyridyl group, a pyrimidyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothienyl group, a quinolyl group, an isoquinolyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, an acridinyl group, a phenothiazinyl group, a phenazinyl group, a xanthenyl group, a thianthrenyl group, a phenoxazinyl group, a phenoxathiinyl group, a chromanyl group, an isochromanyl group, a dibenzothienyl group, a xanthonyl group, a thioxanthonyl group, and a dibenzofuranyl group.

Examples of R ^b7 to R ^b10 in formula (B3) include the same groups as those described above for R ^b3 to R ^b6 in formula (B2).

Preferable specific examples of the anion moiety represented by the formula (B2) described above include:
tetrakis(4-nonafluorobiphenyl)gallium anion,
tetrakis(1-heptafluoronaphthyl)gallium anion,
tetrakis(pentafluorophenyl)gallium anion,
tetrakis(3,4,5-trifluorophenyl)gallate anion,
tetrakis(2-nonaphenylbiphenyl)gallium anion,
tetrakis(2-heptafluoronaphthyl)gallium anion,
tetrakis(7-nonafluoroanthryl)gallium anion,
tetrakis(4'-(methoxy)octafluorobiphenyl)gallium anion,
tetrakis(2,4,6-tris(trifluoromethyl)phenyl)gallium anion,
tetrakis(3,5-bis(trifluoromethyl)phenyl)gallium anion,
tetrakis(2,3-bis(pentafluoroethyl)naphthyl)gallium anion,
tetrakis(2-isopropoxy-hexafluoronaphthyl)gallium anion,
tetrakis(9,10-bis(heptafluoropropyl)heptafluoroanthryl)gallium anion,
tetrakis(9-nonafluorophenanthryl)gallate anion,
tetrakis(4-[tri(isopropyl)silyl]-tetrafluorophenyl)gallium anion,
tetrakis(9,10-bis(p-tolyl)-heptafluorophenanthryl)gallium anion,
tetrakis(4-[dimethyl(t-butyl)silyl]-tetrafluorophenyl)gallium anion,
Examples of the anion include monophenyltris(pentafluorophenyl)gallium anion and monoperfluorobutyltris(pentafluorophenyl)gallium anion, and more preferably, the following anions are included.

Preferred specific examples of the anion moiety represented by formula (B3) include:
tetrakis(4-nonafluorobiphenyl)boron anion,
tetrakis(1-heptafluoronaphthyl)boron anion,
tetrakis(pentafluorophenyl)boron anion,
tetrakis(3,4,5-trifluorophenyl)boron anion,
tetrakis(2-nonaphenylbiphenyl)boron anion,
tetrakis(2-heptafluoronaphthyl)boron anion,
tetrakis(7-nonafluoroanthryl)boron anion,
tetrakis(4'-(methoxy)octafluorobiphenyl)boron anion,
tetrakis(2,4,6-tris(trifluoromethyl)phenyl)boron anion,
tetrakis(3,5-bis(trifluoromethyl)phenyl)boron anion,
tetrakis(2,3-bis(pentafluoroethyl)naphthyl)boron anion,
tetrakis(2-isopropoxy-hexafluoronaphthyl)boron anion,
tetrakis(9,10-bis(heptafluoropropyl)heptafluoroanthryl)boron anion,
tetrakis(9-nonafluorophenanthryl)boron anion,
tetrakis(4-[tri(isopropyl)silyl]-tetrafluorophenyl)boron anion,
tetrakis(9,10-bis(p-tolyl)-heptafluorophenanthryl)boron anion,
tetrakis(4-[dimethyl(t-butyl)silyl]-tetrafluorophenyl)boron anion,
Examples of the anion include monophenyltris(pentafluorophenyl)boron anion and monoperfluorobutyltris(pentafluorophenyl)boron anion, and more preferably, the following anions are included.

Among the counter anions exemplified above, CF ₃ SO ₃ ^-- and ((C ₆ F ₅ ) ₄ B) ^-- are preferred. Here, "C ₆ F ₅ " represents a pentafluorophenyl group.

A commercially available compound can be used as the compound having a cation portion and an anion portion represented by the above formula (c0-I). An example of a commercially available product is CXC-1821 (manufactured by King Industries).

Specific preferred examples of the compound comprising a cation moiety composed of a cation represented by formula (c0-I) and an anion moiety include a quaternary ammonium salt composed of a cation represented by formula (c0-II) and AsF ₆ ^- , a quaternary ammonium salt composed of a cation represented by formula (c0-II) and SbF ₆ ^- , a quaternary ammonium salt composed of a cation represented by formula (c0-II) and PF ₆ ^- , a quaternary ammonium salt composed of a cation represented by formula (c0-II) and CF ₃ SO ₃ ^- , and a quaternary ammonium salt composed of a cation represented by formula (c0-II) and ((C ₆ F ₅ ) ₄ B) ^- . Of these, a quaternary ammonium salt composed of a cation represented by formula (c0-II) and CF ₃ SO ₃ ^- , and a quaternary ammonium salt composed of a cation represented by formula (c0-II) and ((C ₆ F ₅ ) ₄ B) ^- are more preferred.

The content of the thermal acid generator (B) in the curable resin composition is not particularly limited as long as it does not impair the object of the present invention. The content of the thermal acid generator (B) in the curable resin composition is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.3 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the resin (A), and particularly preferably 0.4 parts by mass or more and 5 parts by mass or less from the viewpoint of transparency.

[Solvent (S)]
The curable resin composition contains a solvent (S) for the purpose of adjusting the coating property and viscosity. As the solvent (S), an organic solvent is typically used. The type of the organic solvent is not particularly limited as long as it can uniformly dissolve or disperse the components contained in the curable resin composition.

Suitable examples of organic solvents that can be used as the solvent (S) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, (Poly)alkylene glycol monoalkyl ether acetates such as ethyl ether acetate; other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, tetrahydrofuran, etc.; ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, etc.; alkyl esters of lactate such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, etc.; ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, ethyl hydroxyacetate, ethyl ethyl hydroxyacetate, ethyl ethyl ethyl ester ... ethyl, 2-hydroxy-3-methyl methyl carbonate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl 2-oxobutanoate, and other esters; aromatic hydrocarbons such as toluene and xylene; amides such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. The solvent (S) can be used alone or in combination of two or more.

The amount of the solvent (S) used in the curable resin composition is not particularly limited. In terms of the coatability of the curable resin composition, the amount of the solvent (S) used is, for example, 30% by mass or more and 99.9% by mass or less, and preferably 50% by mass or more and 98% by mass or less, based on the entire curable resin composition.

[Other ingredients]
The curable resin composition may contain additives such as surfactants, thermal polymerization inhibitors, defoamers, silane coupling agents, colorants (pigments, dyes), antioxidants, resins other than the resin (A) (thermoplastic resins, alkali-soluble resins, etc.), inorganic fillers, and organic fillers, as necessary. Any additives may be used that are conventionally known. Examples of surfactants include anionic, cationic, and nonionic compounds. Examples of thermal polymerization inhibitors include hydroquinone and hydroquinone monoethyl ether. Examples of defoamers include silicone and fluorine compounds.

The curable resin composition can be produced by uniformly mixing the components described above in a predetermined ratio. If necessary, the curable resin composition may be filtered using a filter with an opening of a desired size to remove insoluble foreign matter.

<Cured Product>
The cured product according to the present invention can be obtained, for example, by heating the curable resin composition according to the present invention under the same heating conditions as those described below in the method for producing a cured film.

<Method of producing cured film>
In the method for producing a cured film according to the present invention, first, a coating film made of the curable resin composition is formed on at least a part of the main surface of the nitrogen-containing organic compound-containing layer described above. The method for forming the coating film is not particularly limited, and examples thereof include a method of applying the curable resin composition to at least a part of the main surface of the nitrogen-containing organic compound-containing layer.

The coating method is not particularly limited. For example, the curable resin composition is applied to the nitrogen-containing organic compound-containing layer to a desired film thickness using a contact transfer type coating device such as a roll coater, reverse coater, bar coater, or slit coater, or a non-contact type coating device such as a spinner (rotary coating device) or curtain flow coater.

The formed coating film may be pre-baked (post-apply bake (PAB)) as appropriate to remove the organic solvent.

The pre-baking method is not particularly limited, and may be, for example, any of the following: (i) drying using a hot plate at a temperature of 80°C to 120°C (preferably 85°C to 115°C, more preferably 90°C to 110°C) for 30 to 90 seconds (preferably 45 to 75 seconds); (ii) leaving at room temperature for several hours to several days; or (iii) placing in a hot air heater or infrared heater for several tens of minutes to several hours to remove the solvent.

The thickness of the coating film after drying is, for example, preferably 0.1 μm or more and 10 μm or less, more preferably 0.2 μm or more and 5 μm or less, and more preferably 0.3 μm or more and 2 μm or less.

In the method for producing a cured film according to the present invention, the coating film is then heated to form a cured film. The temperature at which the heating is performed is not particularly limited, and is preferably from 180°C to 280°C, more preferably from 180°C to 250°C, and particularly preferably from 180°C to 230°C. The heating time is typically preferably from 1 minute to 60 minutes, more preferably from 2 minutes to 30 minutes, and particularly preferably from 3 minutes to 10 minutes.

The cured film formed in the above manner is applicable to various applications. In particular, the above method allows a cured film to be formed satisfactorily on a green color filter, a blue color filter, or a red color filter that contains a nitrogen-containing organic compound such as a phthalocyanine pigment. The cured film formed on a green color filter, a blue color filter, or a red color filter is particularly preferably used for forming microlenses in a CCD image sensor or a CMOS image sensor.

<Method of manufacturing microlenses>
The manufacturing method of the microlens is as follows:
forming a coating film made of the curable resin composition on a substrate;
heating the coating film to form a cured film;
forming a mask on the cured film having a shape corresponding to the shape of a lens to be formed;
and etching the cured film with the mask to form a lens having the shape of the mask transferred thereto.
The cured film used to form the microlenses is transparent.

For example, when forming a microlens in a CCD image sensor or a CMOS image sensor, it is preferable that the surface layer of the substrate is composed of a color filter selected from the group consisting of a green color filter, a blue color filter, and a red color filter, and that the coating film is formed on the color filter.

The method for forming the cured film is as described above. The method for forming a mask having a shape corresponding to the shape of the lens to be formed on the cured film is not particularly limited. Typically, a dot pattern taking into account the size of the lens is formed by a photolithography method using a resist composition, and then the formed dot pattern is heated to flow, thereby forming a mask having a shape similar to the shape of the lens to be formed.
The temperature at which the dot pattern is caused to flow by heating is appropriately set depending on the type of resist composition.

Then, the cured film is etched together with the mask to form a lens having the shape of the mask transferred thereto. The etching method is not particularly limited, but dry etching is preferred. Dry etching is not particularly limited, and examples thereof include dry etching using plasma (oxygen, argon, _CF4 , etc.), corona discharge, etc.

The microlenses produced on the green, blue, or red color filters by the above method are made of a well-cured product of the above-mentioned curable resin composition, and have excellent heat resistance and solvent resistance.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[Preparation of Curable Resin Composition]
As the resin, the following resins A-1 to A-3 were used.
In the following formulas representing resins A-1 to A-3, the numbers attached to each repeating unit indicate the ratio (mol %) of each repeating unit to all repeating units contained in the resin.
The mass average molecular weight of each resin is as follows.
A-1: 7,000, A-2: 35,000, A-3: 35,000

As the thermal acid generator, the following thermal acid generators B-1 and B-2 were used.

Propylene glycol monomethyl ether acetate (hereinafter referred to as "PGMEA") was used as the solvent.

In the combination shown in Table 1, 100 parts by mass of the above resin, 0 or 1 part by mass of the above thermal acid generator, and PGMEA were uniformly mixed to obtain a curable resin composition (solid concentration: 20% by mass).

[Curing ability on color filter]
The obtained curable resin composition was applied onto a cured product of a green resist having a thickness of 7000 Å, and then dried at 100° C. for 60 seconds to obtain a coating film. The obtained coating film was heated at 200° C. for 5 minutes to be cured, to obtain a cured film having a thickness of 1 μm.
The formed cured film was immersed in acetone for 5 minutes at 25° C. After drying the cured film after immersion, the remaining film ratio was calculated from the film thickness T1 of the cured film before immersion and the film thickness T2 of the cured film after immersion according to the following formula.
Residual film rate (%) = T2/T1 x 100
The curability on the color filter was evaluated according to the following criteria. The results are shown in Table 1.
OK (good): The remaining film rate was 95% or more.
NG (bad): The remaining film rate was less than 95%.

The green resist is a mixture of 10 parts by weight of a phthalocyanine compound, 12 parts by weight of a resin solution (propylene glycol monomethyl ether acetate solution (solid content 50% by weight) of a benzyl methacrylate/methacrylic acid (70/30 [molar ratio]) copolymer with a molecular weight of 30,000), 129 parts by weight of propylene glycol monoethyl ether acetate, 0.5 parts by weight of a fluorine-based surfactant (product name: Megafac F475, manufactured by Dai Nippon Ink Co., Ltd.), 12 parts by weight of dipentaerythritol hexaacrylate, 3 parts by weight of a photopolymerization initiator (2-(o-chlorophenyl)-4,5-diphenylimidazolyl dimer), 2 parts by weight of 2-mercaptobenzothiazole, 0.001 parts by weight of p-methoxyphenol, and 30 parts by weight of a yellow pigment dispersion composition (130 parts by weight of Pigment Yellow It was prepared by mixing 138 and 15 parts by mass of resin solution (propylene glycol monomethyl ether acetate solution (solid content 50% by mass) of benzyl methacrylate/methacrylic acid (70/30 [molar ratio]) copolymer with Mw: 5000), 60 parts by mass of dispersant (Disperbyk-161, manufactured by BYK Japan Co., Ltd.), and 795 parts by mass of propylene glycol monomethyl ether acetate, which was then dispersed).

[Pot life]
The obtained curable resin composition was stored at room temperature for 3 months, and then a cured film was obtained in the same manner as in the above-mentioned "Curability on a color filter". The variation rate of the film thickness was calculated according to the following formula from the above-mentioned T1 and the film thickness T3 of the cured film obtained from the curable resin composition after storage for 3 months.
Film thickness fluctuation rate (%)=(T1-T3)/T1×100
The pot life was evaluated according to the following criteria, and the results are shown in Table 1.
OK (good): The variation rate of the film thickness was 5% or less.
NG (bad): The film thickness fluctuation rate exceeded 5%.

As can be seen from Table 1, the curable resin compositions of the examples showed excellent curability on the layer containing a nitrogen-containing compound that contains a nitrogen atom with a lone electron pair and had a long pot life, whereas the curable resin compositions of the comparative examples showed poor curability or a short pot life.

By using the curable resin composition described above, a microlens can be formed by the following method. Hereinafter, a method for forming a microlens by using the curable resin composition of Example 1 will be described.
First, a 1 μm cured film is obtained on the green resist layer in the same manner as in the above-mentioned residual film rate evaluation. Then, a coating film is formed using the positive photosensitive resin composition described in Example 1 of JP2016-133733A, and the coating film is dried by performing a pre-bake treatment at 100° C. for 90 seconds on a hot plate to form a positive photosensitive resin composition layer with a thickness of 800 nm.
Next, using a KrF exposure device NSR-S203B (Nikon, NA=0.68, S=0.75), the positive photosensitive resin composition layer is selectively irradiated with a KrF excimer laser (248 nm) through a mask. Thereafter, the positive photosensitive resin composition layer is subjected to PEB treatment at 110° C. for 90 seconds, and then developed with a 2.38% by mass tetramethylammonium hydroxide aqueous solution at 23° C. for 60 seconds. Thereafter, the developed resist pattern is rinsed with pure water for 30 seconds. The pure water is shaken off and dried to obtain a dot pattern consisting of dots with a size of 250 nm in length x 250 nm in width. The obtained dot pattern is flowed at 140° C. to obtain a hemispherical pattern.
Using the hemispherical pattern after flow as a mask, an etching process is carried out in a dry etching apparatus using a _CF4 -containing gas, which is a fluorocarbon gas, to obtain a hemispherical cured product.

Claims (8)

A curable resin composition comprising a resin (A), a thermal acid generator (B), and a solvent (S),
The resin (A) has a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group, and a structural unit having an epoxy group,
The structural unit having a chemical structure in which a carboxyl group is protected by an acid-dissociable group is a unit represented by any one of the following formulas (C2-3) to (C2-5):
A curable resin composition.

(In formulae (C2-3) to (C2-5), R ^c6 and R ^c10 to R ^c15 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluorine atom, or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms; R ^c7 to R ^c9 each independently represent a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched fluorinated alkyl group having 1 to 6 carbon atoms; R ^c8 and R ^c9 may be bonded to each other to form a hydrocarbon ring having 5 to 20 carbon atoms together with the carbon atom to which they are bonded; Y ^b represents an aliphatic cyclic group or alkyl group which may have a substituent; p represents an integer of 0 to 4; and q represents 0 or 1.) The curable resin composition according to claim 1, which is used for producing a permanent film on at least a part of a main surface of a nitrogen-containing compound-containing layer,
The nitrogen-containing compound-containing layer is a curable resin composition that contains a nitrogen-containing compound that includes a nitrogen atom having a lone electron pair. The curable resin composition according to claim 1 or 2, which is used to form a microlens. The resin (A) includes a copolymer of a structural unit having a chemical structure in which a carboxyl group is protected by an acid dissociable group and a structural unit having an epoxy group. The curable resin composition according to any one of claims 1 to 3. A cured product of the curable resin composition according to any one of claims 1 to 4. forming a coating film comprising the curable resin composition according to any one of claims 1 to 4 on at least a part of a main surface of a nitrogen-containing compound-containing layer;
heating the coating film to form a cured film;
A method for producing a cured film comprising the steps of: A method for manufacturing a microlens, comprising the steps of:
The manufacturing method includes:
forming a coating film made of the curable resin composition according to any one of claims 1 to 4 on a substrate;
heating the coating film to form a cured film;
forming a mask on the cured film having a shape corresponding to the shape of a lens to be formed;
forming a lens having a shape transferred from the mask by etching the cured film together with the mask;
A manufacturing method comprising: The method for manufacturing a microlens according to claim 7, characterized in that the surface layer of the substrate is composed of a color filter selected from the group consisting of a green color filter, a blue color filter, and a red color filter, and the coating film is formed on the color filter.