Curable resin composition and cured object

Abstract

The purpose of the present invention is to provide a curable resin composition capable of forming cured objects having large thicknesses and satisfactory shapes and a cured object obtained from the curable resin composition. This curable resin composition comprises an alkali-soluble resin (A) which comprises a repeating constituent unit (a1) having a cyclic ether group and a repeating structural unit (a2) having an acid group and has a glass transition temperature of 100°C or lower and an acid value of 40-120 mgKOH / g, a monofunctional monomer (B) having a glass transition temperature of 0°C or higher, and an organic solvent (C), wherein the content of the monofunctional monomer (B) is 10-60 parts by mass per 100 parts by mass of the alkali-soluble resin (A). The curable resin composition contains neither a monofunctional monomer (D) having a glass transition temperature lower than 0°C nor a polyfunctional monomer (E). Alternatively, when the monofunctional monomer (D) is contained, the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A), and when the polyfunctional monomer (E) is contained, the content of the polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A).

Description

Sclerotic resin composition, and cured product

[0001] The present invention relates to a curable resin composition capable of forming a cured product having a large thickness and a good shape, and a cured product.

[0002] Conventionally, curable resin compositions (resist compositions) have been used as materials for creating masks for circuit manufacturing such as semiconductor integrated circuits (ICs) and thin film transistor (TFT) circuits for liquid crystal displays (LCDs), and also as materials for forming partitions for color filters of liquid crystal display elements, partitions for ITO (indium tin oxide) electrodes of liquid crystal display elements, partitions for organic EL display elements, and partitions for circuit wiring boards.

[0003] In recent years, the application range of curable resin compositions has been expanding, such as being used as materials for forming channels (fine channel patterns formed by partitions) of microchannel chips, or for forming microlenses provided in solid-state imaging devices such as charge coupled device (CCD) image sensors and complementary metal-oxide semiconductor (CMOS) image sensors, or for forming microlens arrays in which a large number of microlenses are regularly arranged on a substrate.

[0004] For example, in Patent Document 1, a method for manufacturing a microlens array is proposed, which includes a photosensitive layer forming step of providing a photosensitive layer made of a specific photosensitive resin composition on a substrate or a display element, an exposure step of irradiating a predetermined portion of the photosensitive layer with actinic rays to photocure the exposed portion, a development step of removing portions other than the exposed portion to form a pattern, and a heating step of heating the pattern.

[0005] Japanese Patent Application Laid-Open No. 2011-002655 [[ID=1,7]]

[0006] In recent years, due to improvements in the performance of various products, etc., cured products having a large thickness and a good shape (for example, partitions and microlenses, etc.) have been demanded. However, conventional curable resin compositions have not necessarily been suitable for forming cured products having a large thickness and a good shape (especially microlenses).

[0007] The present invention has been made in view of the above problems, and aims to provide a curable resin composition that can form a cured product having a large thickness and good shape, and a cured product obtained from the curable resin composition.

[0008] The present invention provides the invention in the following aspects: <1> A curable resin composition comprising an alkali-soluble resin (A) having repeating structural units (a1) having a cyclic ether group and repeating structural units (a2) having an acid group, having a glass transition temperature of 100°C or less and an acid value of 40 to 120 mgKOH / g, a monofunctional monomer (B) having a glass transition temperature of 0°C or higher, and an organic solvent (C), wherein the content of the monofunctional monomer (B) is 10 to 60 parts by mass per 100 parts by mass of the alkali-soluble resin (A), and does not contain monofunctional monomers (D) or polyfunctional monomers (E) having a glass transition temperature of less than 0°C, or if it contains the monofunctional monomer (D), the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A), and if it contains the polyfunctional monomer (E), the content of the polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A). <2> The curable resin composition according to <1>, wherein the monofunctional monomer (B) comprises at least one selected from the group consisting of a monofunctional monomer (b1) having an aromatic ring and a monofunctional monomer (b2) having an alicyclic ring. <3> The curable resin composition according to <1> or <2>, wherein the monofunctional monomer (B) has a LogP of 5.0 or less. <4> The curable resin composition according to any one of <1> to <3>, wherein, if the monofunctional monomer (D) is included, the monofunctional monomer (D) has a glass transition temperature of -10°C or less. <5> The curable resin composition according to any one of <1> to <4>, which is a negative-type photoresist material. <6> The curable resin composition according to any one of <1> to <5>, which is a negative-type photoresist material for forming microlenses. <7> A cured product obtained from the curable resin composition according to any one of <1> to <6>. <8> The cured product according to <7>, which is a microlens. <9> The cured product according to <8>, wherein the microlens has a height of 20 μm or more. <10> An alkali-soluble resin for forming microlenses, comprising repeating structural units (a1) having a cyclic ether group and repeating structural units (a2) having an acid group, having a glass transition temperature of 100°C or less and an acid value of 40 to 120 mg KOH / g.

[0009] The curable resin composition of the present invention contains the alkali-soluble resin (A), the monofunctional monomer (B), and the organic solvent (C), and can form cured products (e.g., partitions and microlenses) with a large thickness and good shape with good pattern-forming properties. In particular, using the curable resin composition of the present invention, hemispherical microlenses with a large thickness can be formed with good pattern-forming properties.

[0010] In the present invention, (meth)acrylate means acrylate and / or methacrylate, (meth)acrylic means acrylic and / or methacrylic, (meth)acryloyl means acryloyl and / or methacryloyl, and (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0011] 1. Curable Resin Composition The curable resin composition of the present invention comprises an alkali-soluble resin (A) having a glass transition temperature of 100°C or less and an acid value of 40 to 120 mgKOH / g, a monofunctional monomer (B) having a glass transition temperature of 0°C or higher, and an organic solvent (C), wherein the content of the monofunctional monomer (B) is 10 to 60 parts by mass per 100 parts by mass of the alkali-soluble resin (A), and does not contain monofunctional monomers (D) or polyfunctional monomers (E) having a glass transition temperature of less than 0°C, or if it contains the monofunctional monomer (D), the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A), and if it contains polyfunctional monomers (E), the content of the polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A). The curable resin composition of the present invention will be described in detail below.

[0012] The reason why a cured product with a large thickness and good shape can be obtained by using the curable resin composition of the present invention is not limited by theory, but can be considered as follows. The curable resin composition of the present invention allows for high concentrations of the alkali-soluble resin (A) and monofunctional monomer (B), thus enabling the formation of thicker coating films. This is thought to be due to the high solubility of the alkali-soluble resin (A) and monofunctional monomer (B) in organic solvents (C). Furthermore, since the alkali-soluble resin (A) contains repeating structural units (a1) having cyclic ether groups, during post-development heat treatment (post-bake), the cyclic ether groups can open their rings and form a cross-linked structure through reaction with reactive functional groups (e.g., acid groups and amino groups) of the alkali-soluble resin (A) and monofunctional monomer (B). As a result, excessive deformation of the pattern shape due to heat (e.g., spreading in the planar direction) during post-development heat treatment (post-bake) is suppressed, and a cured product with a large thickness and good shape can be obtained.

[0013] [Alkali-soluble resin (A)] Alkali-soluble resin (A) comprises repeating structural units having cyclic ether groups (a1) and repeating structural units having acid groups (a2), has a glass transition temperature of 100°C or less, and an acid value of 40 to 120 mgKOH / g.

[0014] <Repeating structural unit (a1) having a cyclic ether group> The monomer (a1') that forms the repeating structural unit (a1) having a cyclic ether group may have a functional group containing an ethylenically unsaturated double bond (hereinafter also referred to as a "radical polymerizable functional group") and a cyclic ether group, and is a monomer capable of forming a crosslinked structure by ring opening of the cyclic ether group, but is not particularly limited otherwise. Note that the repeating structural unit having a cyclic ether group is synonymous with the repeating structural unit having a cyclic ether structure.

[0015] The radical polymerizable functional group is not particularly limited and includes, for example, a vinyl group, an allyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group. From the viewpoint of polymerizability with monomers that form other structural units, a (meth)acryloyloxy group is preferred. The monomer (a1') may have one radical polymerizable functional group, or it may have two or more radical polymerizable substituents of the same or different types, but from the viewpoint of imparting good developability to the curable resin composition (hereinafter simply referred to as "from the viewpoint of developability"), it is preferable to have one radical polymerizable functional group.

[0016] A cyclic ether group is a group that contains carbon atoms and oxygen atoms as atoms constituting the ring. During post-baking, the cyclic ether group can undergo ring-opening and form a cross-linked structure by reacting with reactive functional groups (e.g., acid groups and amino groups) of an alkali-soluble resin (A) and a monofunctional monomer (B). The monomer (a1') may have one cyclic ether group, or it may have two or more cyclic ether groups of the same or different type.

[0017] Examples of cyclic ether groups include epoxy groups, epoxycycloalkyl groups, and oxetanyl groups. Examples of epoxycycloalkyl groups include epoxycyclopentyl groups, epoxycyclohexyl groups, epoxycycloheptyl groups, and epoxycyclooctyl groups. From the viewpoint of easily adjusting the crosslinking density by heating temperature during post-baking treatment after development, thereby easily forming a cured product of a desired shape, epoxycycloalkyl groups and oxetanyl groups are preferred as cyclic ether groups.

[0018] The radical polymerizable functional group and the cyclic ether group may be directly bonded or bonded via a linking group. The linking group is not particularly limited and includes, for example, a linear or branched aliphatic saturated hydrocarbon group or aliphatic unsaturated hydrocarbon group, and an organic group in which some of the carbon atoms constituting the hydrocarbon group are substituted with heteroatoms (e.g., oxygen, nitrogen, and sulfur atoms). Furthermore, the hydrocarbon group and the organic group may have various substituents (e.g., halogen groups, alkyl groups, alkenyl groups, and alkoxy groups) and functional groups (e.g., ester bonds, amide bonds, ether bonds, thioether bonds, and urethane bonds). From the viewpoint of developability, the linking group is preferably a linear or branched aliphatic saturated hydrocarbon group or aliphatic unsaturated hydrocarbon group having 1 to 10 carbon atoms, more preferably a linear or branched aliphatic saturated hydrocarbon group having 1 to 10 carbon atoms, and even more preferably a linear or branched aliphatic saturated hydrocarbon group having 1 to 5 carbon atoms.

[0019] Examples of the monomer (a1') include glycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, and (3-ethyloxetan-3-yl)methyl (meth)acrylate.

[0020] In the alkali-soluble resin (A), the content of the repeating structural unit (a1) is usually 5 to 75 mol%, and from the viewpoint of forming a cured product with a large thickness and good shape with good pattern-forming properties, it is preferably 10 to 60 mol%, more preferably 15 to 50 mol%, and even more preferably 25 to 45 mol%.

[0021] In the alkali-soluble resin (A), the repeating structural unit (a1) may consist of one type or two or more types.

[0022] <Repeating structural unit having an acid group (a2)> The monomer (a2') that forms the repeating structural unit having an acid group (a2) may have a radical polymerizable functional group and an acid group, but is not particularly limited otherwise.

[0023] The radical polymerizable functional group is not particularly limited and includes, for example, a vinyl group, an allyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group. From the viewpoint of polymerizability with monomers that form other structural units, a (meth)acryloyloxy group is preferred. The monomer (a2') may have one radical polymerizable functional group, or it may have two or more radical polymerizable substituents of the same or different types, but from the viewpoint of developability, it is preferable to have one radical polymerizable functional group.

[0024] An acid group is a group that can act as a proton donor. Acid groups are not particularly limited and include, for example, carboxyl groups, acid anhydride groups, sulfonic acid groups, and phosphoric acid groups, but from the viewpoint of ease of manufacturing alkali-soluble resin (A), carboxyl groups are preferred. The monomer (a2') may have one acid group, or two or more acid groups of the same or different type, but from the viewpoint of developability, it is preferable to have one acid group.

[0025] The radical polymerizable functional group and the acid group may be directly bonded or bonded via a linking group. The linking group is not particularly limited and includes, for example, a linear or branched aliphatic saturated hydrocarbon group or aliphatic unsaturated hydrocarbon group, or an organic group in which some of the carbon atoms constituting the hydrocarbon group are substituted with heteroatoms (e.g., oxygen, nitrogen, and sulfur atoms). Furthermore, the hydrocarbon group and the organic group may have various substituents (e.g., halogen groups, alkyl groups, alkenyl groups, and alkoxy groups) or functional groups (e.g., ester bonds, amide bonds, ether bonds, thioether bonds, and urethane bonds). From the viewpoint of developability, the linking group is preferably a linear or branched aliphatic saturated hydrocarbon group or aliphatic unsaturated hydrocarbon group having 1 to 10 carbon atoms, or an organic group in which some of the carbon atoms constituting the hydrocarbon group are substituted with oxygen atoms.

[0026] Examples of the monomer (a2') include carboxyl group-containing monomers such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, maleic acid, and itaconic acid; and carboxylic acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride. The monomer (a2') is preferably a carboxyl group-containing monomer, and more preferably (meth)acrylic acid.

[0027] The content of the repeating structural unit (a2) can be appropriately adjusted so that the acid value of the alkali-soluble resin (A) is 40 to 120 mg KOH / g, but is usually 5 to 50 mol%, preferably 10 to 40 mol%, more preferably 15 to 35 mol%, and even more preferably 20 to 35 mol% from the viewpoint of alkali developability.

[0028] In the alkali-soluble resin (A), the repeating structural unit (a2) may consist of one type or two or more types.

[0029] <Repeating structural units (other structural units) derived from copolymer monomers> Alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate, to the extent that the effects of the present invention are not impaired; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; alkoxy group-containing (meth)acrylates such as ethoxyethyl (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate )Acrylates and alicyclic (meth)acrylates such as dicyclopentanyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; amino group-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate; maleimides such as cyclohexyl maleimide, phenyl maleimide, methyl maleimide, ethyl maleimide, n-butyl maleimide, and lauryl maleimide; and repeating structural units derived from copolymer monomers such as styrene may also be included. These repeating structural units may be included one or two or more types. The alkali-soluble resin (A) preferably contains at least one selected from the group consisting of repeating structural units derived from hydroxyl group-containing (meth)acrylate, repeating structural units derived from maleimide, and aromatic ring-containing (meth)acrylate, from the viewpoint of developing properties, ease of achieving a viscosity suitable for application to a substrate, and ease of forming a thick film. In the alkali-soluble resin (A), the total content of repeating structural units derived from copolymer monomers is preferably 5 to 65 mol%, more preferably 15 to 55 mol%, and even more preferably 25 to 50 mol%.

[0030] <Glass Transition Temperature> In this invention, the Tg of the alkali-soluble resin (A) is a theoretical value calculated from the Tg of the homopolymer of each structural unit constituting the alkali-soluble resin (A) and the ratio of each structural unit, using the following FOX formula: FOX formula: 1 / Tg = w1 / Tg1 + w2 / Tg2 + ... + wn / Tgn (Tg: glass transition temperature (K) of the alkali-soluble resin (A), Tg1, Tg2, ... Tgn: glass transition temperatures (K) of the homopolymer of each structural unit, w1, w2, ... wn: weight fraction of each structural unit) The theoretical glass transition temperature obtained from the above FOX formula is in good agreement with the measured glass transition temperature obtained by differential scanning calorimetry (DSC) or dynamic viscoelasticity. Therefore, if there are circumstances that make it difficult to calculate the theoretical value, the glass transition temperature may be specified in JIS. It can be measured using a differential scanning calorimeter (DSC) in accordance with K 6240:2011.

[0031] The glass transition temperature (hereinafter also referred to as "Tg") of the alkali-soluble resin (A) is 100°C or lower. By setting the Tg of the alkali-soluble resin (A) to 100°C or lower, the pattern becomes more easily softened by heat during post-development heat treatment (post-bake), making it easier to form a cured product of the desired shape. From the viewpoint of making it easier to form a cured product of the desired shape during post-development heat treatment (post-bake), the Tg of the alkali-soluble resin (A) is preferably 90°C or lower, more preferably 80°C or lower, and even more preferably 70°C or lower. The Tg of alkali-soluble resin (A) can be adjusted to 100°C or below, particularly within the preferred range described above, by confirming the Tg of the homopolymer of each structural unit using "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999), etc., and determining the ratio and type of each structural unit using the FOX formula described above.

[0032] <Acid Value> From the viewpoint of imparting good developability to the curable resin composition, the alkali-soluble resin (A) has an acid value of 40 to 120 mg KOH / g, preferably 50 to 110 mg KOH / g, and more preferably 60 to 100 mg KOH / g. The acid value can be adjusted to the desired value by appropriately adjusting the content of the repeating structural unit (a2).

[0033] In this invention, the acid value represents the mass (mg) of potassium hydroxide required to neutralize the acid groups contained in 1 g of alkali-soluble resin (A), and is a theoretical value calculated from the molecular weight and the number of functional groups (number of acid groups) per molecule based on the structure of alkali-soluble resin (A). Specifically, the acid value of alkali-soluble resin (A) is a value obtained by [moles of acid groups in alkali-soluble resin (A) (moles)] × [56.11 / amount of alkali-soluble resin (A) (g)].

[0034] <Other Composition> The weight-average molecular weight (MW) of the alkali-soluble resin (A) is not particularly limited, but when the curable resin composition is used as a resist material, it is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, and even more preferably 8,000 to 20,000, from the viewpoint of obtaining good exposure sensitivity and good developability, and obtaining a cured product with a large thickness. The weight-average molecular weight is determined by gel permeation chromatography (GPC) in accordance with JIS K 7252-1:2016 and is a value converted using standard polystyrene.

[0035] The alkali-soluble resin (A) can be produced by known methods, for example, by radical polymerization of a monomer composition comprising the monomer (a1') and the monomer (a2'), and optionally the copolymer monomer.

[0036] As a method for introducing acid groups into the side chains of alkali-soluble resin (A), in addition to copolymerizing carboxyl group-containing monomers or carboxylic acid anhydride group-containing monomers, other methods may be employed, such as adding an epoxy group-containing compound such as glycidyl (meth)acrylate to a polymer copolymerized with carboxyl group-containing monomers such as (meth)acrylic acid, and then adding an acid anhydride to the resulting hydroxyl group; or adding an acid anhydride to a polymer copolymerized with epoxy group-containing monomers such as glycidyl (meth)acrylate, and then adding an acid anhydride to the resulting hydroxyl group.

[0037] The alkali-soluble resin (A) may be a random copolymer, block copolymer, alternating copolymer, or periodic copolymer containing the repeating structural units (a1) and (a2). In addition, the alkali-soluble resin (A) may be a random copolymer, block copolymer, alternating copolymer, or periodic copolymer containing repeating structural units derived from the copolymer monomer, in addition to the repeating structural units (a1) and (a2).

[0038] Alkali-soluble resin (A) is suitably used for forming lenses (microlenses), photospacers, partitions, interlayer insulating films, protective films, optical waveguides, and planarization films, and is particularly suitably used for forming microlenses.

[0039] In the curable resin composition, the content of alkali-soluble resin (A) is usually about 30 to 90% by mass relative to the total solid content of the curable resin composition, and from the viewpoint of further improving the effects of the present invention, it is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, and even more preferably 60 to 85% by mass.

[0040] [Monofunctional Monomer (B)] Monofunctional monomer (B) has a glass transition temperature of 0°C or higher. Having a Tg of monofunctional monomer (B) of 0°C or higher makes it less likely for the coating film obtained by applying the curable resin composition to a substrate or the like and drying it to become cloudy. This reduces the likelihood of curing defects due to insufficient exposure sensitivity, allowing for the formation of good patterns.

[0041] From the viewpoint of suppressing the clouding of the coating film of the curable resin composition, the Tg of the monofunctional monomer (B) is preferably 10 to 150°C, more preferably 15 to 140°C, still more preferably 20 to 130°C. Further, when the curable resin composition is used in the production of a microlens (array) including the above-described exposure step and heating step, when the Tg of the monofunctional monomer (B) is within the above range, the pattern after the exposure step becomes easy to thermally flow in the heating step and excessive thermal flow can be suppressed, and it becomes easy to form a microlens with a good shape.

[0042] In the present invention, the Tg of the monofunctional monomer (B) means the Tg of the homopolymer of the monofunctional monomer (B). When the known literature value (for example, the value described in "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999)) can be adopted for the Tg of the monofunctional monomer (B), that value is adopted. In other cases, for example, the monofunctional monomer (B) is bulk polymerized to form a homopolymer, and the value obtained by measuring the Tg of the homopolymer is taken as the Tg of the monofunctional monomer (B). The same applies to the Tg of the monofunctional monomer (D) described later.

[0043] Examples of the monofunctional monomer (B) include monofunctional monomers (b1) having an aromatic ring such as ethoxylated - o - phenylphenol (meth)acrylate, benzyl (meth)acrylate, biphenyl - 2 - yl - (meth)acrylate, and phenoxyethyl (meth)acrylate; monofunctional monomers (b2) having an alicyclic ring such as dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2 - methyl - 2 - adamantyl (meth)acrylate. These may be used alone or in combination of two or more.

[0044] From the viewpoint of obtaining good exposure sensitivity and good developability, the LogP of the monofunctional monomer (B) is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less.

[0045] In the present invention, LogP is an index representing the hydrophobicity of a chemical substance, and is a value (so-called CLogP) obtained by calculation using ChemDraw Professional 21.0.0 of PerkinElmer.

[0046] Examples of the monofunctional monomer (B) having a LogP of 5.0 or less include dicyclopentanyl acrylate (LogP: 2.58), isobornyl acrylate (LogP: 3.34), cyclohexyl acrylate (LogP: 2.19), 2-methyl-2-adamantyl acrylate (LogP: 2.87), benzyl acrylate (LogP: 2.37), biphenyl-2-yl acrylate (LogP: 3.98), and phenoxyethyl acrylate (LogP: 2.30).

[0047] In the curable resin composition, the content of the monofunctional monomer (B) is 10 to 60 parts by mass per 100 parts by mass of the alkali-soluble resin (A), and from the viewpoint of further improving the effects of the present invention, it is preferably 15 to 55 parts by mass, more preferably 20 to 50 parts by mass.

[0048] [Organic solvent (C)] The curable resin composition of the present invention contains an organic solvent (C). Examples of organic solvents include ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; alcohols such as methanol, ethanol, isopropanol, n-butanol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and chloroform and dimethyl sulfoxide. These solvents may be used individually or in combination of two or more. The content of the organic solvent (C) can be appropriately set according to the optimal viscosity and solubility of the constituent components when using the curable resin composition. Generally, the ratio of solids to organic solvent (C) of the curable resin composition is 30 to 70:70 to 30 by mass, preferably 35 to 65:65 to 35, and more preferably 40 to 60:60 to 40.

[0049] [Monofunctional monomer (D)] The curable resin composition of the present invention does not contain monofunctional monomer (D) having a glass transition temperature of less than 0°C, or if it contains the monofunctional monomer (D), the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A).

[0050] In the curable resin composition of the present invention, if the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A), the coating film obtained by applying the curable resin composition to a substrate or the like and drying it is less likely to become cloudy. As a result, curing defects due to insufficient exposure sensitivity are less likely to occur, and a good pattern can be formed.

[0051] If the curable resin composition of the present invention contains a monofunctional monomer (D), the monofunctional monomer (D) may have a glass transition temperature of -10°C or lower, or -20°C or lower.

[0052] Examples of monofunctional monomers (D) include dodecyl acrylate (Tg: -23°C), isostearyl acrylate (Tg: -18°C), hydroxyethyl acrylate (Tg: -15°C), isobutyl acrylate (Tg: -26°C), n-octyl acrylate (Tg: -65°C), isononyl acrylate (Tg: -58°C), isodecyl acrylate (Tg: -62°C), and nonyl acrylate (Tg: -37°C). These may be used individually or in combination of two or more.

[0053] When the curable resin composition of the present invention contains a monofunctional monomer (D), the content of the monofunctional monomer (D) is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 1 part by mass or less, per 100 parts by mass of the alkali-soluble resin (A).

[0054] [Polyfunctional monomer (E)] The curable resin composition of the present invention does not contain polyfunctional monomer (E), or if it contains polyfunctional monomer (E), the content of polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A).

[0055] In the curable resin composition of the present invention, if the content of the polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A), the alkali-soluble resin (A) is less likely to crosslink excessively upon light irradiation, and the pattern becomes easier to soften with heat during post-development heat treatment (post-bake), making it easier to form a cured product of a desired shape.

[0056] Examples of polyfunctional monomers (E) include polyfunctional aromatic vinyl monomers such as divinylbenzene, diallyl phthalate, and diallylbenzene phosphonate; and polyfunctional (meth)acrylates such as (di)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, EO-added di(meth)acrylate of bisphenol A, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and tri(meth)acrylate of tris(hydroxyethyl) isocyanurate. These may be used individually or in combination of two or more types.

[0057] When the curable resin composition of the present invention contains a polyfunctional monomer (E), the content of the polyfunctional monomer (E) is preferably 1 part by mass or less per 100 parts by mass of the alkali-soluble resin (A).

[0058] [Optional components] <Photopolymerization initiator> The curable resin composition of the present invention may contain a photopolymerization initiator. The photopolymerization initiator is not particularly limited and examples include benzoin, benzoin methyl ether and its alkyl ethers such as benzoin, benzoin ethyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; anthraquinones such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone and 1-chloroanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; acylphosphine oxides and xanthones. These photopolymerization initiators may be used individually or in combination of two or more.

[0059] In the curable resin composition, the content of the photopolymerization initiator is not particularly limited, but when the total solid content of the curable resin composition is considered to be 100% by mass, it is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, and even more preferably 0.3 to 5% by mass.

[0060] <Other Resins and Oligomers> The curable resin composition of the present invention may contain known alkali-soluble resins other than the alkali-soluble resin (A) of the present invention; radical polymerizable oligomers such as unsaturated polyesters, epoxy acrylates, urethane acrylates, and polyester acrylates; and curable resins such as epoxy resins, to the extent that the effects of the present invention are not impaired.

[0061] <Photopolymerization Initiator> The curable resin composition of the present invention may contain a photopolymerization initiator. Examples of photopolymerization initiators include trifunctional thiol compounds such as 1,3,5-tris(3-mercaptopropionyloxyethyl)-isocyanurate, 1,3,5-tris(3-mercaptobutyloxyethyl)-isocyanurate (manufactured by Showa Denko, Karenz MT® NR1), and trimethylolpropanetris(3-mercaptopropionate); tetrafunctional thiol compounds such as pentaerythritol tetrakis(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptobutyrate) (manufactured by Showa Denko, Karenz MT® PEI); and polyfunctional thiol compounds such as dipentaerythritol hexakis(3-mercaptopropionate). These photopolymerization initiators may be used individually or in combination of two or more.

[0062] <Thermal polymerization initiator> The curable resin composition of the present invention may contain a thermal polymerization initiator. Examples of thermal polymerization initiators include organic peroxides such as cumene hydroperoxide, diisopropylbenzene peroxide, di-t-butyl peroxide, lauryl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexanoate, and t-amyl peroxy-2-ethylhexanoate; and azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobis(2-methylpropionate). These thermal polymerization initiators may be used individually or in combination of two or more.

[0063] <Additives> The curable resin composition of the present invention may contain known additives such as fillers such as aluminum hydroxide, talc, clay, and barium sulfate, crosslinking agents, surfactants (e.g., silicone-based surfactants), dyes, pigments, defoaming agents, coupling agents, leveling agents, sensitizers, mold release agents, lubricants, plasticizers, antioxidants, ultraviolet absorbers, flame retardants, polymerization inhibitors, thickeners, and dispersants, to the extent that they do not impair the effects of the present invention.

[0064] [Uses of the curable resin composition] The curable resin composition of the present invention is used as a negative-type or positive-type photoresist material, and is preferably used as a negative-type photoresist material, and more preferably as a negative-type photoresist material for microlens formation, from the viewpoint of easily forming patterns of cured products with a large thickness.

[0065] 2. Cured Products The cured products of the present invention are obtained by curing the curable resin composition. As a method for producing the cured products, for example, one method is to coat the curable resin composition onto a substrate or various functional layers to form a desired shape, and then cure the curable resin composition by irradiating it with light (for example, ultraviolet light). However, the method is not limited to this method, and known methods can be used depending on the purpose and application of forming the cured product. The curing conditions are adjusted as appropriate depending on the curable resin composition used.

[0066] The cured product of the present invention is suitably used as a cured product having a pattern shape such as a lens (microlens), photospacer, partition wall, interlayer insulating film, protective film, optical waveguide, and planarization film, and is particularly suitably used as a microlens.

[0067] The method for forming a cured product having a patterned shape is not particularly limited. For example, the curable resin composition can be applied to a substrate or various functional layers, dried to form a coating film, and then formed by photolithography. In photolithography, either a positive or negative type may be used, but a negative type is preferable when forming a thick film pattern. As a method for forming a cured product having a patterned shape in negative type photolithography, for example, a photomask is placed on the coating film, the coating film is photocured by irradiation with ultraviolet light, an alkaline aqueous solution is sprayed onto the coating film after ultraviolet irradiation to dissolve and remove the unexposed areas, and the remaining exposed areas are washed with water and developed to form a cured product having a patterned shape. Post-baking may be performed thereafter.

[0068] The film thickness of the pattern formed using the curable resin composition of the present invention is not particularly limited, but it is possible to form relatively thick film patterns with film thicknesses of 20 μm or more, 30 μm or more, 40 μm or more, and even 50 μm or more using the curable resin composition of the present invention. Furthermore, the pattern formed using the curable resin composition of the present invention can have high adhesion to the substrate after development (high developability) and can be a high-resolution pattern. Note that the film thickness of the pattern refers to the height of the cured portion in the pattern, and is the height of the partition when the cured portion is used as a partition.

[0069] Furthermore, as a method for manufacturing microlenses, for example, a method is to form a dot pattern consisting of rectangular dots and grid-like spaces on a substrate using the curable resin composition of the present invention, and then form a microlens pattern (microlens array, etc.) by heat flow through the dot pattern by heating. By using the curable resin composition of the present invention, a microlens of a desired shape (for example, a hemispherical shape) can be formed by adjusting the heating temperature in the heat flow.

[0070] The reason why microlenses (arrays) of a desired shape can be formed using the curable resin composition of the present invention is not limited by theory, but can be considered as follows. As described above, since the alkali-soluble resin (A) contains repeating structural units (a1) having cyclic ether groups, during heat treatment (heat flow) after development, the cyclic ether groups can open their rings and form a crosslinked structure through reaction with reactive functional groups (e.g., acid groups and amino groups) of the alkali-soluble resin (A) and monofunctional monomer (B). In addition, during heat flow after development, the cured product deforms due to the heat. As a result of the inventors' investigations, it was found that the timing of deformation of the cured product and the formation of the crosslinked structure are important for forming microlenses of a good shape, such as a hemispherical shape, by heat flow. More specifically, it was found that if the crosslinked structure is formed when the deformation is insufficient, the cured product becomes roughly rectangular, and if the formation of the crosslinked structure is too late, the crosslinked structure is formed after the deformation of the cured product has progressed excessively, resulting in a tendency for the cured product to become flattened. The curable resin composition of the present invention employs a repeating structural unit (a1) having a cyclic ether group as a structural unit that reacts with a reactive functional group, in order to adjust the timing of crosslinking and deformation. Furthermore, by setting the Tg of the alkali-soluble resin (A) to 100°C or lower, the timing of deformation of the cured product and the formation of the crosslinking structure can be appropriately controlled. Therefore, it is believed that microlenses with good shape can be obtained by using the curable resin composition of the present invention.

[0071] The substrate is not particularly limited as long as it is a substrate used as the target for forming microlens patterns. An example of a suitable substrate is a silicon substrate on which solid-state image sensors, a first planarization film, a color filter, and a second planarization film are formed. In such a substrate, a first planarization film having a flat surface is formed so as to cover the solid-state image sensors scattered at predetermined positions on the silicon substrate. A color filter is formed on the first planarization film at a position above the position of each solid-state image sensor. Then, a second planarization film having a flat surface is formed so as to cover the color filter. In this substrate, the direction from the silicon substrate to the second planarization film is considered upward, and the direction from the second planarization film to the silicon substrate is considered downward.

[0072] To form a microlens pattern on a substrate, first, a dot pattern is formed on the substrate using the curable resin composition. The method for forming the dot pattern is not particularly limited; for example, it may be formed by a printing method such as inkjet printing, or by a photolithography method including patterning by exposure and development.

[0073] In photolithography, for example, a negative-type photolithography method can be suitably used, in which a photomask is placed on a coating film of the curable resin composition, the coating film is photocured by irradiation with ultraviolet light, an alkaline aqueous solution is sprayed onto the coating film after ultraviolet irradiation to dissolve and remove the unexposed areas, and the remaining exposed areas are washed with water and developed to form a dot pattern. However, the curable resin composition of the present invention is not limited to use in negative-type photolithography, but can also be used in positive-type photolithography.

[0074] By using the curable resin composition of the present invention, microlenses (microlens arrays) with heights of 20 μm or more, 30 μm or more, 40 μm or more, and even 50 μm or more can be formed in a desired shape (for example, a hemispherical shape).

[0075] The present invention will be described below with reference to examples, but the present invention is not limited in any way by these examples.

[0076] Manufacturing Example 1 [Synthesis of Alkali-Soluble Resin (A-1)] In a glass flask equipped with a heating / cooling / stirring device, reflux condenser, and nitrogen inlet tube, 12.4 g of cyclohexylmaleimide, 24.9 g of (3-ethyloxetan-3-yl)methyl methacrylate, 4.1 g of 2-hydroxyethyl methacrylate, 6.8 g of methacrylic acid, and 115.2 g of propylene glycol monomethyl ether acetate (PGMEA) were charged. After replacing the gas phase in the system with nitrogen, 2.6 g of 2,2'-azobisisobutyronitrile was added, and the mixture was heated to 80°C and reacted at the same temperature for 8 hours to obtain a solution containing alkali-soluble resin (A-1). The synthesized alkali-soluble resin (A-1) contains 22 mol% repeating structural units derived from cyclohexylmaleimide, 43 mol% repeating structural units derived from (3-ethyloxetan-3-yl)methyl methacrylate, 10 mol% repeating structural units derived from 2-hydroxyethyl methacrylate, and 25 mol% repeating structural units derived from methacrylic acid. The synthesized alkali-soluble resin (A-1) had a Tg of 64°C, an acid value of 74 mgKOH / g, and a weight-average molecular weight (Mw) of 14,000 according to GPC (standard substance: polystyrene).

[0077] Manufacturing Example 2 [Synthesis of Alkali-Soluble Resin (A-2)] 174.6 g of phenoxyethyl methacrylate, 118.2 g of (3,4-epoxycyclohexyl)methyl methacrylate, 37.3 g of methacrylic acid, and 612.8 g of cyclohexanone were charged into a glass flask equipped with a heating / cooling / stirring device, reflux condenser, and nitrogen inlet tube. After replacing the gas phase in the system with nitrogen, 23.1 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added, and the mixture was heated to 65°C and reacted at the same temperature for 13 hours to obtain a solution containing alkali-soluble resin (A-2). The synthesized alkali-soluble resin (A-2) contains 45 mol% of repeating structural units derived from phenoxyethyl methacrylate, 32 mol% of repeating structural units derived from (3,4-epoxycyclohexyl)methyl methacrylate, and 23 mol% of repeating structural units derived from methacrylic acid. Furthermore, the synthesized alkali-soluble resin (A-2) had a Tg of 61°C, an acid value of 72 mgKOH / g, and a weight-average molecular weight (Mw) of 12,500 according to GPC (standard substance: polystyrene).

[0078] Manufacturing Example 3 [Synthesis of Alkali-Soluble Resin (A'-1)] 10.0 g of cyclohexylmaleimide, 15.5 g of glycidyl methacrylate, 3.3 g of 2-hydroxyethyl methacrylate, 5.5 g of methacrylic acid, and 80.0 g of propylene glycol monomethyl ether acetate (PGMEA) were charged into a glass flask equipped with a heating / cooling / stirring device, reflux condenser, and nitrogen inlet tube. After replacing the gas phase in the system with nitrogen, 5.7 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added, and the mixture was heated to 65°C and reacted at the same temperature for 6 hours to obtain a solution containing alkali-soluble resin (A'-1). The synthesized alkali-soluble resin (A'-1) contains 22 mol% repeating structural units derived from cyclohexylmaleimide, 43 mol% repeating structural units derived from glycidyl methacrylate, 10 mol% repeating structural units derived from 2-hydroxyethyl methacrylate, and 25 mol% repeating structural units derived from methacrylic acid. Furthermore, the synthesized alkali-soluble resin (A'-1) had a Tg of 101°C, an acid value of 74.1 mgKOH / g, and a weight-average molecular weight (Mw) of 12600 according to GPC (standard substance: polystyrene).

[0079] Manufacturing Example 4 [Synthesis of Alkali-Soluble Resin (A'-2)] 8.6 g of cyclohexylmaleimide, 25.3 g of ethoxylated-o-phenylphenol acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-LEN-10), 2.9 g of 2-hydroxyethyl methacrylate, 4.7 g of methacrylic acid, and 96.7 g of propylene glycol monomethyl ether acetate (PGMEA) were charged into a glass flask equipped with a heating / cooling / stirring device, reflux condenser, and nitrogen inlet tube. After replacing the gas phase in the system with nitrogen, 2.9 g of 2,2'-azobisisobutyronitrile was added, and the mixture was heated to 80°C and reacted at the same temperature for 8 hours to obtain a solution containing alkali-soluble resin (A'-2). The synthesized alkali-soluble resin (A'-2) contains 22 mol% repeating structural units derived from cyclohexylmaleimide, 43 mol% repeating structural units derived from ethoxylated-o-phenylphenol acrylate, 10 mol% repeating structural units derived from 2-hydroxyethyl methacrylate, and 25 mol% repeating structural units derived from methacrylic acid. The synthesized alkali-soluble resin (A'-2) had a Tg of 68°C, an acid value of 66.7 mgKOH / g, and a weight-average molecular weight (Mw) of 15200 according to GPC (standard substance: polystyrene).

[0080] Example 1 [Preparation of Curable Resin Composition] A solution containing 100 parts by mass of the alkali-soluble resin (A-1) prepared in Production Example 1, 20 parts by mass of ethoxylated-o-phenylphenol acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-LEN-10, Tg: 24°C), 30 parts by mass of dicyclopentanyl acrylate (Tg: 120°C, LogP: 2.58), 2 parts by mass of photopolymerization initiator (manufactured by Tronly, PBG-301), and 0.1 parts by mass of surfactant (manufactured by Bic Chemie Japan Co., Ltd., BYK-307) were mixed to prepare a curable resin composition with a solid content of 43.5% by mass.

[0081] Examples 2-6 and Comparative Examples 1-6 [Preparation of Curable Resin Compositions] Curable resin compositions were prepared in the same manner as in Example 1, except that the composition was changed to that shown in Table 1. The monomers listed in Table 1 are as follows. The units of content of each component listed in Table 1 are parts by mass. • B-1: Ethoxylated-o-phenylphenol acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-LEN-10, Tg: 24℃) • B-2: Dicyclopentanyl acrylate (Tg: 120℃, LogP: 2.58) • B-3: Isobornyl acrylate (Tg: 97℃, LogP: 3.34) • D-1: Dodecyl acrylate (Tg: -23℃, LogP: 5.22) • D-2: Isostearyl acrylate (Tg: -18℃, LogP: 7.72) • E-1: Bisphenol A diacrylate with 3.8 molar EO added (manufactured by Osaka Organic Chemical Industry Co., Ltd., V#700HV)

[0082] [Preparation of Microlens Patterns] On each 10 cm x 10 cm square glass substrate, the curable resin compositions prepared in Examples 1-6 and Comparative Examples 1-6 were applied to a film thickness of approximately 40 μm using a spin coater to form a coating film. The coating film was then heated on a 100°C hot plate for 2 minutes to completely remove the solvent. Subsequently, 1 cm of the obtained coating film was applied. 2 A pattern mask with 100 holes per unit, each with a diameter of 100 μm, is used to transmit light from an ultra-high pressure mercury lamp at a rate of 100 mJ / cm². 2 Irradiated (illuminance equivalent to i-ray: 21 mW / cm²) 2 The exposure method was projection. Afterwards, alkaline development was performed using a 2.38% TMAH aqueous solution. Then, the samples were washed with water and post-baked at 220°C for 30 minutes to create microlens patterns. The thickness of the fabricated microlenses was then measured using scanning electron microscope (SEM) images. The results are shown in Table 1. Note that the curable resin compositions prepared in Comparative Examples 1, 4, and 5 could not be used to create microlens patterns.

[0083] [Transparency Evaluation] In the fabrication of the microlens patterns described above, the obtained coating film was visually observed and its transparency was evaluated according to the following criteria. The results are shown in Table 1. <Transparency Evaluation Criteria> ○: Transparent. ×: Cloudy.

[0084] [Evaluation of Developability] <Evaluation Criteria for Developability> ○: The coating can be developed within 90 seconds using a 2.38% TMAH aqueous solution. ×: When developing the coating using a 2.38% TMAH aqueous solution, it takes more than 90 seconds.

[0085] [Evaluation of Microlens Shape] The fabricated microlenses were observed using a scanning electron microscope (SEM), and their shapes were evaluated according to the following criteria. The results are shown in Table 1. <Evaluation Criteria for Microlens Shape> ○: Hemispherical shape and good lens shape. ×: Poor lens shape, or excessive melting prevented the formation of a lens shape.

[0086]

[0087] As shown in Table 1, the curable resin compositions of Examples 1 to 6 were able to form microlenses with good pattern formation properties, having a large thickness and a good hemispherical shape. On the other hand, the curable resin compositions of Comparative Examples 1, 4, and 5 could not form microlens patterns because the coating film became cloudy. The curable resin compositions of Comparative Examples 2 and 6 could not form hemispherical microlenses. In the curable resin composition of Comparative Example 3, the pattern melted excessively (spreading in the planar direction) due to heat during the post-development heat treatment (post-bake), and it was not possible to form microlenses.

[0088] The curable resin composition of the present invention is suitably used as a negative-type or positive-type photoresist material.

Claims

1. A curable resin composition comprising: an alkali-soluble resin (A) having repeating structural units (a1) having a cyclic ether group and repeating structural units (a2) having an acid group, having a glass transition temperature of 100°C or less and an acid value of 40 to 120 mgKOH / g; a monofunctional monomer (B) having a glass transition temperature of 0°C or higher; and an organic solvent (C), wherein the content of the monofunctional monomer (B) is 10 to 60 parts by mass per 100 parts by mass of the alkali-soluble resin (A); and which does not contain monofunctional monomers (D) or polyfunctional monomers (E) having a glass transition temperature of less than 0°C, or if it contains the monofunctional monomer (D), the content of the monofunctional monomer (D) is 25 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A); and if it contains the polyfunctional monomer (E), the content of the polyfunctional monomer (E) is 2 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A).

2. The curable resin composition according to claim 1, wherein the monofunctional monomer (B) comprises at least one selected from the group consisting of a monofunctional monomer having an aromatic ring (b1) and a monofunctional monomer having an alicyclic ring (b2).

3. The curable resin composition according to claim 1, wherein the monofunctional monomer (B) has a LogP of 5.0 or less.

4. The curable resin composition according to claim 1, wherein, if the monofunctional monomer (D) is included, the monofunctional monomer (D) has a glass transition temperature of -10°C or lower.

5. A curable resin composition according to any one of claims 1 to 4, wherein the material is a negative-type photoresist material.

6. A curable resin composition according to any one of claims 1 to 4, which is a negative-type photoresist material for forming microlenses.

7. A cured product obtained from the curable resin composition according to any one of claims 1 to 4.

8. The cured product according to claim 7, wherein the cured product is a microlens.

9. The cured product according to claim 8, wherein the microlens has a height of 20 μm or more.

10. An alkali-soluble resin for microlens formation, comprising repeating structural units having a cyclic ether group (a1) and repeating structural units having an acid group (a2), having a glass transition temperature of 100°C or less and an acid value of 40 to 120 mg KOH / g.

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