Curable composition and pattern forming method

Abstract

Adopted is a curable composition comprising an (X) component, which is niobium oxide nanoparticles, a (B) component, which is a polymerizable compound, and a (C) component, which is a polymerization initiator. Also adopted is a pattern formation method comprising: a step for using said curable composition to form a curable film (2) on a substrate (1); a step for pressing a mold (3) having a relief pattern onto the curable film (2) so as to transfer the relief pattern to the curable film (2); a step for curing the curable film (2) to which the relief pattern has been transferred, while pressing the mold (3) onto the curable film (2), so as to form a cured film; and a step for separating the mold (3) from the cured film to form a pattern (2').

Description

[Technical Field]

[0001] The present invention relates to a curable composition and a pattern forming method. This application claims priority based on Japanese Patent Application No. 2021-077326, filed in Japan on April 30, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Lithography is a core technology in the manufacturing process of semiconductor devices, and with the increasing integration of semiconductor integrated circuits (ICs) in recent years, further miniaturization of wiring is progressing. Common miniaturization techniques include shortening the wavelength of light sources by using shorter wavelength light sources such as KrF excimer lasers, ArF excimer lasers, F2 lasers, EUV (extreme ultraviolet light), EB (electron beam), and X-rays, as well as increasing the numerical aperture (NA) of the lenses in the exposure equipment (high NA).

[0003] In this context, nanoimprint lithography, a method for forming fine patterns in semiconductors, is expected to be promising in terms of productivity and other factors. This method involves pressing a mold with a predetermined pattern onto a curable film formed on a substrate to transfer the pattern of the mold to the curable film. Nanoimprint lithography uses photocurable compositions containing photocurable compounds that harden with light (ultraviolet light, electron beam). In this case, a mold having a predetermined pattern is pressed onto a curable film containing the photocurable compound, then light is irradiated to harden the photocurable compound, and then the mold is peeled off from the hardened film to obtain a transfer pattern (structure).

[0004] Photocurable compositions used in nanoimprint lithography require specific properties, including ease of application to substrates by methods such as spin coating, and curability upon heating or exposure. Poor application to the substrate can lead to variations in the film thickness of the photocurable composition, resulting in reduced pattern transfer when a mold is pressed onto the curable film. Curability is also a crucial property for maintaining the desired dimensions of the pattern formed by mold pressing. In addition, photocurable compositions are required to have good mold release properties when peeling the mold from the cured film.

[0005] In recent years, nanoimprint lithography has been explored for improving the functionality of 3D sensors for autonomous driving and AR waveguides for augmented reality (AR) glasses. For 3D sensors and AR glasses, there is a need for higher refractive indices in the permanent film materials that constitute part of the device. One known method for increasing the refractive index of nanoimprint materials is to add metal oxide nanoparticles (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-160285 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] To further increase the refractive index of nanoimprint materials, the use of titania nanoparticles (titanium dioxide nanoparticles) as metal oxide nanoparticles is being considered. However, titania nanoparticles have photocatalytic properties and exhibit strong oxidizing activity upon irradiation with ultraviolet light, decomposing organic matter. Therefore, when using titania nanoparticles, there are challenges regarding the light resistance of the cured film.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a curable composition capable of forming a cured film having an increased refractive index and good light resistance, and a patterning method. **Means for Solving the Problems**

[0009] In order to solve the above problems, the present invention employs the following configuration. [1] A curable composition containing a (X) component: niobium oxide nanoparticles, a (B) component: a polymerizable compound, and a (C) component: a polymerization initiator. [2] The curable composition according to [1], wherein the (C) component is a photo radical polymerization initiator. [3] The curable composition according to [1] or [2], wherein the content of the (X) component is 25 to 70 parts by mass and the content of the (B) component is 30 to 75 parts by mass with respect to 100 parts by mass of the total content of the (X) component and the (B) component. [4] The curable composition according to any one of [1] to [3], wherein the volume average primary particle diameter of the (X) component is 40 nm or less. [5] The curable composition according to any one of [1] to [4], which is for photoimprint lithography.

[0010] [6] A patterning method including a step of forming a curable film on a substrate using the curable composition according to any one of [1] to [5], a step of pressing a mold having a concavo-convex pattern against the curable film to transfer the concavo-convex pattern to the curable film, a step of curing the curable film having the concavo-convex pattern transferred thereto while pressing the mold against the curable film to form a cured film, and a step of peeling the mold from the cured film. **Advantages of the Invention**

[0011] According to the present invention, it is possible to provide a curable composition capable of forming a cured film having an increased refractive index and good light resistance, and a patterning method. **Brief Description of the Drawings**

[0012] [Figure 1] It is a schematic process diagram for explaining an embodiment of a nanoimprint patterning method. [Figure 2] It is a schematic process diagram for explaining an example of an arbitrary process.

Mode for Carrying Out the Invention

[0013] In this specification and the claims of this patent, "aliphatic" is a relative concept with respect to aromatic, and is defined to mean a group, compound, etc. that does not have aromaticity. "Alkyl group" shall include linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified. The same applies to the alkyl group in an alkoxy group. "(Meth)acrylate" means at least one of acrylate and methacrylate. When it is described as "may have a substituent", it includes both the case of substituting a hydrogen atom (-H) with a monovalent group and the case of substituting a methylene group (-CH2-) with a divalent group. "Exposure" is a concept that includes the entire irradiation of radiation.

[0014] (Curable Composition) The curable composition according to the first aspect of the present invention contains a component (X): niobium oxide nanoparticles, a component (B): a polymerizable compound, and a component (C): a polymerization initiator.

[0015] <(X) Component> The component (X) is niobium oxide nanoparticles. "Nanoparticle" means a particle having a volume average primary particle diameter on the order of nanometers (less than 1000 nm). Niobium oxide nanoparticles are niobium oxide particles having a volume average primary particle diameter on the order of nanometers. The volume average primary particle diameter is a value measured by the dynamic light scattering method.

[0016] Niobium oxide exists in forms with oxidation states of +5 (Nb2O5), +4 (NbO2), +3 (Nb2O3), and +2 (NbO). The most common oxide is considered to be niobium pentoxide (Nb2O5).

[0017] The volume-average primary particle diameter of component (X) is preferably 40 nm or less. The volume-average primary particle diameter of component (X) is preferably 0.1 to 40 nm, more preferably 0.2 to 30 nm, even more preferably 0.5 to 30 nm, even more preferably 1 to 30 nm, and particularly preferably 1 to 25 nm. When the volume-average primary particle diameter of component (X) is within the above preferred range, the niobium oxide nanoparticles are well dispersed in the curable composition. In addition, the refractive index of the cured film is more easily increased. Furthermore, the packing properties of the curable composition into the mold are improved.

[0018] In this embodiment, commercially available niobium oxide nanoparticles can be used as component (X). Examples of commercially available niobium oxide nanoparticles include "Bailal Nb-G6000," a product manufactured by Taki Chemical Co., Ltd.

[0019] In the curable composition of this embodiment, component (X) may be used alone or in combination of two or more types.

[0020] The content of component (X) in the curable composition of this embodiment is preferably 25 to 70 parts by mass, more preferably 25 to 65 parts by mass, and even more preferably 30 to 65 parts by mass, based on 100 parts by mass of the total content of component (X) and component (B) described later. If the content of component (X) is above the lower limit of the preferred range described above, the refractive index of the cured film formed using the curable composition can be easily increased. On the other hand, if the content of component (X) is below the upper limit of the preferred range described above, the light resistance of the cured film formed using the curable composition will be better.

[0021] <(B) component> Component (B) is a polymerizable compound. A polymerizable compound is a compound that has polymerizable functional groups. A "polymerizable functional group" is a group that enables compounds to polymerize through radical polymerization or other means, and includes, for example, a group containing multiple bonds between carbon atoms, such as an ethylenic double bond. Polymerization here may be a reaction that proceeds by light irradiation or a reaction that proceeds by heating.

[0022] Examples of polymerizable functional groups include vinyl group, allyl group, acryloyl group, methacryloyl group, fluorovinyl group, difluorovinyl group, trifluorovinyl group, difluorotrifluoromethylvinyl group, trifluoroallyl group, perfluoroallyl group, trifluoromethylacryloyl group, nonylfluorobutylacryloyl group, vinyl ether group, fluorinated vinyl ether group, allyl ether group, fluorinated allyl ether group, styryl group, vinylnaphthyl group, fluorinated styryl group, fluorinated vinylnaphthyl group, norbornyl group, fluorinated norbornyl group, and silyl group. Among these, vinyl group, allyl group, acryloyl group, and methacryloyl group are preferred, and acryloyl group and methacryloyl group are more preferred.

[0023] Polymerizable compounds (monofunctional monomers) having one polymerizable functional group include, for example, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and other (meth)acrylates containing aliphatic polycyclic structures; dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine, and other (meth)acrylates containing aliphatic monocyclic structures; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth) (Meth)acrylates containing chain-like structures such as acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc.;Benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, 2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, EO-modified p-cumylphenol (meth)acrylates containing aromatic ring structures such as 2-bromophenoxyethyl (meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, EO-modified phenoxy(meth)acrylate, PO-modified phenoxy(meth)acrylate, polyoxyethylene nonylphenyl ether (meth)acrylate; tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate; Examples include methyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate; diacetone (meth)acrylamide, isobutoxymethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, t-octyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate, N,N-diethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide; 2-methchloroyloxyethyl acid phosphate, terminally methacrylate siloxane monomer, etc.

[0024] Examples of commercially available monofunctional monomers include, for example, Aronics M101, M102, M110, M111, M113, M117, M5700, TO-1317, M120, M150, M156 (all manufactured by Toagosei Co., Ltd.); MEDOL10, MIBDOL10, CHDOL10, MMDOL30, MEDOL30, MIBDOL30, CHDOL30, LA, IBXA, 2-MTA, HPA, Viscoat #150, #155, #158, #190, #192, #193, #220, #2000, #2100, #2150 (all manufactured by Osaka Organic Chemical Industry Co., Ltd.); Light acrylate BO-A, EC-A, DMP-A, THF-A, HOP-A, HOA-MPE, HOA-MPL, HOA(N), PO-A, P-200A, NP-4EA, NP-8EA, IB-XA, epoxy ester M-600A, light ester P-1M (all manufactured by Kyoeisha Chemical Co., Ltd.); KAYARAD Examples include TC110S, R-564, R-128H (all manufactured by Nippon Kayaku Co., Ltd.); NK ester AMP-10G, AMP-20G (both manufactured by Shin Nakamura Chemical Industry Co., Ltd.); FA-511A, FA-512A, FA-513A, FA-BZA (all manufactured by Hitachi Chemical Co., Ltd.); PHE, CEA, PHE-2, PHE-4, BR-31, BR-31M, BR-32 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); VP (manufactured by BASF); ACMO, DMAA, DMAPAA (all manufactured by KJ Chemicals Co., Ltd.); X-22-2404 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

[0025] Examples of polymerizable compounds (difunctional monomers) having two polymerizable functional groups include trimethylolpropane di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate, and 2-methachlorooxyethyl acid phosphate.

[0026] Examples of commercially available difunctional monomers include light acrylates 3EG-A, 4EG-A, 9EG-A, NP-A, DCP-A, BP-4EAL, BP-4PA, and light ester P-2M (all manufactured by Kyoeisha Chemical Co., Ltd.); and APG-100, APG-200, APG-400, and APG-700 (manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0027] Examples of polymerizable compounds having three or more polymerizable functional groups include polymerizable siloxane compounds, polymerizable silsesquioxane compounds, and polyfunctional monomers having three or more polymerizable functional groups.

[0028] Examples of polymerizable siloxane compounds include compounds having both an alkoxysilyl group and a polymerizable functional group within the molecule. Examples of commercially available polymerizable siloxane compounds include the following products manufactured by Shin-Etsu Chemical Co., Ltd.: "KR-513", "X-40-9296", "KR-511", "X-12-1048", and "X-12-1050".

[0029] Polymerizable silsesquioxane compounds have a main chain skeleton consisting of Si-O bonds and have the following chemical formula: [(RSiO 3 / 2 ) n Examples of compounds represented by the formula ] (wherein R represents an organic group and n represents a natural number) include: R represents a monovalent organic group, and examples of monovalent organic groups include monovalent hydrocarbon groups which may have substituents. Examples of these hydrocarbon groups include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include alkyl groups having 1 to 20 carbon atoms, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group, with alkyl groups having 1 to 12 carbon atoms being preferred. Examples of aromatic hydrocarbon groups include phenyl groups, naphthyl groups, benzyl groups, tolyl groups, and styryl groups, which have 6 to 20 carbon atoms. Substituents that a monovalent hydrocarbon group may have include (meth)acryloyl, hydroxyl, sulfanyl, carboxyl, isocyanate, amino, and ureido groups. Furthermore, the -CH2- group in the monovalent hydrocarbon group may be replaced with -O-, -S-, or carbonyl groups. However, polymerizable silsesquioxane compounds have three or more polymerizable functional groups. Examples of polymerizable functional groups include vinyl groups, allyl groups, methacryloyl groups, and acryloyl groups.

[0030] Chemical formula: [(RSiO 3 / 2 ) n The compound represented by ] may be of any type: cage-type, ladder-type, or random-type. The cage-type silsesquioxane compound may be a complete cage type or an incomplete cage type in which part of the cage is open.

[0031] Examples of commercially available polymerizable silsesquioxane compounds include products manufactured by Toagosei Co., Ltd., such as "MAC-SQ LP-35," "MAC-SQ TM-100," "MAC-SQ SI-20," and "MAC-SQ HDM."

[0032] Examples of polyfunctional monomers having three or more polymerizable functional groups include ethoxylated (3) trimethylolpropane triacrylate, ethoxylated (3) trimethylolpropane trimethacrylate, ethoxylated (6) trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropane triacrylate, ethoxylated (15) trimethylolpropane triacrylate, ethoxylated (20) trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, propoxylated (3) glyceryl triacrylate, propoxylated (3) glyceryl triacrylate, propoxylated (5.5) glyceryl triacrylate, propoxylated (3) trimethylolpropane triacrylate, propoxylated (6) trimethylolpropane triacrylate, and trimethylolpropane triacrylate. Examples include trifunctional monomers such as ropane triacrylate, trimethylolpropane trimethacrylate, tris-(2-hydroxyethyl)-isocyanurate triacrylate, tris-(2-hydroxyethyl)-isocyanurate trimethacrylate, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, and EO,PO-modified trimethylolpropane tri(meth)acrylate; tetrafunctional monomers such as ditrimethylolpropane tetraacrylate, ethoxylated (4) pentaerythritol tetraacrylate, and pentaerythritol tetra(meth)acrylate; and monomers with five or more functions such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

[0033] Examples of commercially available polyfunctional monomers include the products "A-9300-1CL," "AD-TMP," "A-9550," and "A-DPH" manufactured by Shin Nakamura Chemical Industry Co., Ltd.; "KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd.; "SA-TE60" manufactured by Sakamoto Pharmaceutical Co., Ltd.; and "Light Acrylate TMP-A" manufactured by Kyoeisha Chemical Co., Ltd. In addition, as commercially available products other than those described above, for example, products named "NK Oligo EA-1010NT2", "NK Ester A-BPML", etc. manufactured by Shin-Nakamura Chemical Co., Ltd. can also be used as the component (B).

[0034] The component (B) may be a polymerizable sulfur compound (hereinafter also referred to as the (BS) component). The "polymerizable sulfur compound" is a polymerizable compound containing a sulfur atom in its molecule. That is, the polymerizable sulfur compound is a monomer containing a sulfur atom and having a polymerizable functional group.

[0035] Examples of the (BS) component include compounds having a diaryl sulfide skeleton. Examples of the compounds having a diaryl sulfide skeleton include compounds represented by the following general formula (bs-1).

[0036] [Chemical formula] [In the formula, R 11 ~R 14 and R 21 ~R 24 each independently represents a hydrogen atom, an alkyl group or a halogen atom, and R 5 represents a polymerizable functional group.]

[0037] In the formula (bs-1), R 11 ~R 14 and R 21 ~R 24 each independently represents a hydrogen atom, an alkyl group or a halogen atom. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms. The alkyl group may be linear, branched or cyclic. The alkyl group is preferably linear or branched. Examples of linear alkyl groups include methyl, ethyl, n-propyl, and n-butyl groups. Examples of branched alkyl groups include isopropyl, sec-butyl, and tert-butyl groups. Among these, the alkyl group is preferably a methyl or ethyl group, with the methyl group being more preferred.

[0038] The aforementioned R 11 ~R 14 and R 21 ~R 24 Examples of halogen atoms in this compound include fluorine, chlorine, bromine, and iodine atoms. Chlorine atoms are preferred as the halogen atom.

[0039] R 11 ~R 14 and R 21 ~R 24 The component is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom, a methyl group or an ethyl group, and even more preferably a hydrogen atom.

[0040] In the above formula (bs-1), R 5 This represents a polymerizable functional group. Examples of polymerizable functional groups include those listed above. Among these, vinyl groups, allyl groups, acryloyl groups, and methacryloyl groups are preferred as polymerizable functional groups, with acryloyl groups and methacryloyl groups being more preferred. R 5 The group is preferably an acryloyl group or a methacryloyl group, and more preferably an acryloyl group or a methacryloyl group.

[0041] Examples of the (BS) component include bis(4-methacryloylthiophenyl) sulfide and bis(4-acryloylthiophenyl) sulfide. Among these, bis(4-methacryloylthiophenyl) sulfide is preferred as the (BS) component.

[0042] In the curable composition of this embodiment, component (B) may be used alone or in combination of two or more types. Component (B) preferably contains a photopolymerizable compound. Of these, component (B) more preferably contains a polyfunctional photopolymerizable compound, and even more preferably contains a polyfunctional monomer having three or more polymerizable functional groups. By including the polyfunctional photopolymerizable compound, curing is further accelerated when forming a cured film using the curable composition, and the strength and stress resistance of the cured film can be increased. Alternatively, component (B) may be a combination of a polyfunctional photopolymerizable compound and a monofunctional monomer. By using these in combination, curing is further accelerated when forming a cured film using the curable composition, and the stress resistance of the cured film can be increased.

[0043] The content of component (B) in the curable composition of this embodiment is preferably 30 to 75 parts by mass, more preferably 35 to 75 parts by mass, and even more preferably 35 to 70 parts by mass, based on 100 parts by mass of the total content of component (X) and component (B). If the content of component (B) is above the lower limit of the preferred range described above, the light resistance of the cured film formed using the curable composition will be improved. In addition, the strength of the cured film will be increased. On the other hand, if the content of component (B) is below the upper limit of the preferred range described above, the refractive index of the cured film formed using the curable composition will be increased. In addition, the stress resistance of the cured film will be improved.

[0044] In the curable composition of this embodiment, in order to easily improve the light resistance of the cured film, it is preferable that the content of component (X) is 25 to 70 parts by mass and the content of component (B) is 30 to 75 parts by mass per 100 parts by mass of the total content of component (X) and component (B), more preferably that the content of component (X) is 25 to 65 parts by mass and the content of component (B) is 35 to 75 parts by mass, and even more preferably that the content of component (X) is 30 to 65 parts by mass and the content of component (B) is 35 to 70 parts by mass.

[0045] <(C) component> Component (C) is a polymerization initiator. Component (C) is a compound that initiates or promotes the polymerization of component (B) by exposure or heating.

[0046] (C) Examples of components include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one (2-hydroxy-2-methyl-1-phenylpropanone), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, and 2,2-dimethoxy-1,2-diphenyl Ethan-1-one, bis(4-dimethylaminophenyl)ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(o-acetyloxime), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 4-benzoyl-4'-methyldimethyl sulfide, 4-dimethylamino Benzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, 4-dimethylamino-2-ethylhexylbenzoic acid, 4-dimethylamino-2-isoamylbenzoic acid, benzyl-β-methoxyethyl acetal, benzyl dimethyl ketal, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, o-methyl o-benzoylbenzoate, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 1-chloro- 4-Propoxythioxanthone, Thioxanthene, 2-Chlorothioxanthene, 2,4-Diethylthioxanthene, 2-Methylthioxanthene, 2-Isopropylthioxanthene, 2-Ethylanthraquinone, Octamethylanthraquinone, 1,2-Benzanthraquinone, 2,3-Diphenylanthraquinone, Azobisisobutyronitrile, Benzoyl peroxide, Cumen peroxide, 2-Mercaptobenzimidal, 2-Mercaptobenzoxazole, 2-Mercaptobenzothiazole, 2-(o-Chlorophenyl)-4,5-di(m-methoxyphenyl)-imidazolyl dimer, benzophenone, 2-chlorobenzophenone, p,p'-bisdimethylaminobenzophenone, 4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone, 3,3-dimethyl-4-methoxybenzophenone, benzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzoin butyl ether, acetophenone, 2,2-diethoxy Acetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, dichloroacetophenone, trichloroacetophenone, p-tert-butylacetophenone, p-dimethylaminoacetophenone, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, α,α-dichloro-4-phenoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, dibenzosverone, pentyl-4- Dimethylaminobenzoate, 9-phenylacridine, 1,7-bis-(9-acridinyl)heptane, 1,5-bis-(9-acridinyl)pentane, 1,3-bis-(9-acridinyl)propane, p-methoxytriazine, 2,4,6-tris(trichloromethyl)-s-triazine, 2-methyl-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(5-methylfuran-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl) 2-(4-diethylamino-2-methylphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(2-(3,4-dimethoxyphenyl)ethenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-n-butoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-Bis-trichloromethyl-6-(3-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)styrylphenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)styrylphenyl-s-triazine; Ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide; Diacyl peroxides such as isobutyryl peroxide, bis(3,5,5-trimethylhexanoyl) peroxide; p-menthane hydroperoxide, 1, Examples include hydroperoxides such as 1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxides such as 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane; peroxyketals such as 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane; peroxyesters such as t-butylperoxyneodecanoate and 1,1,3,3-tetramethylperoxyneodecanoate; peroxydicarbonates such as di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate; and azo compounds such as azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobisisobutyrate.

[0047] Among the above, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one (2-hydroxy-2-methyl-1-phenylpropanone), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 2,2-dimethoxy-2-phenylacetophenone are preferred.

[0048] (C) The component can be obtained from a commercially available product. (C) Examples of commercially available products containing this ingredient include BASF's "IRGACURE 907," "IRGACURE 369," and "IRGACURE 819"; and IGM Resins BV's "Omnirad 184," "Omnirad 651," "Omnirad 819," and "Omnirad 1173," among others.

[0049] (C) Component is preferably small in molecular weight. A smaller molecular weight of (C) component tends to reduce haze further. The molecular weight of (C) component is preferably 500 or less, more preferably 400 or less, even more preferably 350 or less, and particularly preferably 300 or less. The lower limit of the molecular weight of (C) component is not particularly limited, but examples include 100 or more, 150 or more, or 200 or more. The molecular weight of (C) component can be, for example, 100 to 500, preferably 150 to 500, more preferably 150 to 400, even more preferably 150 to 350, and particularly preferably 150 to 300.

[0050] In the curable composition of this embodiment, component (C) may be used alone or in combination of two or more types. The aforementioned component (C) is preferably a photoradical polymerization initiator, as it is suitable for nanoimprint lithography.

[0051] The content of component (C) in the curable composition of this embodiment is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 5 to 15 parts by mass, based on 100 parts by mass of the total content of component (X) and component (B). If the content of component (C) is within the above-mentioned preferred range, a good cured film can be formed.

[0052] <Optional ingredients> The curable composition of the embodiment may contain, in addition to components (X), (B), and (C), other components (optional components). Examples of such optional components include metal oxide nanoparticles other than component (X) (component (X2)), solvents (component (S)), and miscible additives (component (E): for example, surfactants, color separation inhibitors, degradation inhibitors, mold release agents, diluents, antioxidants, heat stabilizers, flame retardants, plasticizers, and other additives for improving the properties of the cured film).

[0053] ≪(X) component other than metal oxide nanoparticles: (X2) component≫ The curable composition of this embodiment may also contain metal oxide nanoparticles other than component (X) (component (X2)). The volume-average primary particle diameter of component (X2) is preferably 100 nm or less. (X2) As component X2, commercially available metal oxide nanoparticles can be used. Examples of metal oxides include titanium (Ti), zirconium (Zr), aluminum (Al), silicon (Si), zinc (Zn), or magnesium (Mg) oxide particles.

[0054] As component (X2), commercially available metal oxide nanoparticles can be used. Examples of commercially available titania nanoparticles include the TTO series (TTO-51(A), TTO-51(C), etc.), TTO-S, and V series (TTO-S-1, TTO-S-2, TTO-V-3, etc.) manufactured by Ishihara Sangyo Co., Ltd.; Titania Sol LDB-014-35 manufactured by Ishihara Sangyo Co., Ltd.; the MT series (MT-01, MT-05, MT-100SA, MT-500SA, etc.) and NS405 manufactured by Teika Co., Ltd.; ELECOM V-9108 manufactured by JGC Catalysts & Chemicals Co., Ltd.; and STR-100A-LP manufactured by Sakai Chemical Industry Co., Ltd. Examples of commercially available zirconia nanoparticles include UEP (manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd.), UEP-100 (manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd.), PCS (manufactured by Nippon Denko Co., Ltd.), JS-01, JS-03, and JS-04 (manufactured by Nippon Denko Co., Ltd.).

[0055] In the curable composition of this embodiment, component (X2) may be used alone or in combination of two or more types. Among these, from the viewpoint of refractive index, titania (TiO2) nanoparticles or zirconia (ZrO2) nanoparticles are preferred as component (X2). If the curable composition of this embodiment contains component (X2), it is preferable to adjust the amount of component (X2) considering the light resistance of the cured film, etc.

[0056] ≪Solvent: (S) component≫ The curable composition of this embodiment may contain a solvent (component (S)). Component (S) is used to dissolve or disperse and mix the above-mentioned components (X), (B), (C), and any other desired component.

[0057] (S) components include, for example, water; methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-pentyl alcohol, s-pentyl alcohol, t-pentyl alcohol, isopentyl alcohol, 2-methyl-1-propanol, 2-ethylbutanol, neopentyl alcohol, n-butanol, s-butanol, t-butanol, 1-propanol, n-hexanol, 2-heptanol, 3-heptanol, 2-methyl-1-butanol, 2-methyl Chain-like alcohols such as 2-butanol, 4-methyl-2-pentanol, 1-butoxy-2-propanol, propylene glycol monopropyl ether, 5-methyl-1-hexanol, 6-methyl-2-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, 2-(2-butoxyethoxy)ethanol; cyclopentanemethanol, 1-cyclopentylethanol, cyclohexanol, cyclo Examples include cyclic alcohols such as hexahexanemethanol, cyclohexaneethanol, 1,2,3,6-tetrahydrobenzyl alcohol, exo-norborneol, 2-methylcyclohexanol, cycloheptanol, 3,5-dimethylcyclohexanol, benzyl alcohol, and terpionol; compounds having ester bonds such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, or dipropylene glycol monoacetate; and derivatives of polyhydric alcohols such as monomethyl ethers, monoethyl ethers, monopropyl ethers, monobutyl ethers, or monophenyl ethers of the aforementioned polyhydric alcohols or compounds having ester bonds [among these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred].

[0058] In the curable composition of this embodiment, component (S) may be used alone or in combination of two or more types. Among the above, water, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monomethyl ether (PGME) are preferred as the (S) component.

[0059] The amount of component (S) used is not particularly limited and can be set appropriately according to the coating thickness of the curable composition. For example, it can be used in an amount of about 100 to 1000 parts by mass per 100 parts by mass of the total content of component (X) and component (B).

[0060] <<Surfactants>> The curable composition of this embodiment may contain a surfactant to adjust its applicability and other properties. Examples of surfactants include silicone-based surfactants and fluorine-based surfactants. Examples of silicone-based surfactants that can be used include BYK-077, BYK-085, BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-320, BYK-322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-335, BYK-341, BYK-344, BYK-345, BYK-346, BYK-348, BYK-354, BYK-355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, and BYK-390 (all manufactured by BYK Chemie). Examples of fluorine-based surfactants include F-114, F-177, F-410, F-411, F-450, F-493, F-494, F-443, F-444, F-445, F-446, F-470, F-471, F-472SF, F-474, F-475, F-477, F-478, F-479, F-480SF, F-482, F-483, F-484, F-486, F-487, F-172D, MCF-350SF, and TF-10. 25SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF-1129, TF-1126, TF-1130, TF-1116SF, TF-1131, TF-1132, TF-1027SF, TF-1441, TF-1442 (all manufactured by DIC Corporation); Polyfox series PF-636, PF-6320, PF-656, PF-6520 (all manufactured by Omnova Corporation), etc. can be used.

[0061] In the curable composition of this embodiment, one surfactant may be used alone, or two or more surfactants may be used in combination. If the curable composition of this embodiment contains a surfactant, the amount of surfactant is preferably 0.01 to 3 parts by mass, more preferably 0.02 to 1 part by mass, and even more preferably 0.03 to 0.5 parts by mass, based on 100 parts by mass of the total amount of component (X) and component (B). When the surfactant content is within the aforementioned preferred range, the curable composition exhibits good coatability.

[0062] The cured film formed using the curable composition of this embodiment has a preferred refractive index of 1.50 or higher at a wavelength of 530 nm, more preferably 1.55 or higher, and even more preferably 1.60 or higher. Because the curable composition of this embodiment can form a cured film with a high refractive index, it can be suitably used in applications requiring a high refractive index, such as 3D sensors and AR waveguides for AR (augmented reality) glasses. The refractive index of the cured film can be measured using a spectroscopic ellipsometer.

[0063] The curable composition of this embodiment described above contains (X) component: niobium oxide nanoparticles, (B) component: polymerizable compound, and (C) component: polymerization initiator. In the curable composition of this embodiment, niobium oxide, which does not have photocatalytic activity in the visible light region, is used as the metal oxide, and these nanoparticles are utilized. This makes it possible to increase the refractive index of the cured film and to form a cured film with good light resistance. For example, by applying the curable composition of this embodiment, a fine pattern can be easily formed in a cured film with a refractive index of 1.50 or higher at a wavelength of 530 nm and excellent light resistance.

[0064] In addition, the curable composition of this embodiment also exhibits good fine pattern transfer properties during pattern formation. That is, such a curable composition is useful as a material for forming fine patterns on a substrate using imprint technology, and is particularly suitable for optical imprint lithography. In particular, it offers advantageous effects in applications requiring high refractive index and light resistance, such as 3D sensors for autonomous driving and AR waveguides for AR (augmented reality) glasses. Furthermore, the curable composition of this embodiment is also useful as a material for anti-reflective coatings, for example.

[0065] (Pattern formation method) A pattern forming method according to a second aspect of the present invention comprises the steps of: forming a curable film on a substrate using the curable composition of the first aspect described above (hereinafter referred to as "step (i)"); pressing a mold having an uneven pattern onto the curable film to transfer the uneven pattern to the curable film (hereinafter referred to as "step (ii)"); curing the curable film on which the uneven pattern has been transferred while pressing the mold onto the curable film to form a cured film (hereinafter referred to as "step (iii)"); and peeling the mold from the cured film (hereinafter referred to as "step (iv)").

[0066] Figure 1 is a schematic process diagram illustrating one embodiment of a pattern formation method.

[0067] [Process (i)] In step (i), a curable film is formed on the substrate using the curable composition of the first embodiment described above. As shown in Figure 1(A), the curable composition according to the first embodiment described above is applied to the substrate 1 to form a curable film 2. In Figure 1(A), the mold 3 is positioned above the curable film 2.

[0068] The substrate 1 can be selected according to various applications, such as substrates for electronic components or substrates on which a predetermined wiring pattern has been formed. More specifically, examples include metal substrates such as silicon, silicon nitride, copper, chromium, iron, and aluminum, and glass substrates. Examples of materials for the wiring pattern include copper, aluminum, nickel, and gold. Furthermore, the shape of the substrate 1 is not particularly limited; it may be in the form of a plate or a roll. Also, depending on the combination with the mold, the substrate 1 can be selected to be either light-transmitting or light-impermeable.

[0069] Methods for applying the curable composition to the substrate 1 include spin coating, spray coating, inkjet coating, roll coating, and rotary coating. Since the curable film 2 functions as a mask in an etching process of the substrate 1 that may be performed later, it is preferable that the film thickness when applied to the substrate 1 be uniform. From this point of view, a spin coating method is preferred when applying the curable composition to the substrate 1. The thickness of the curable film 2 can be appropriately selected depending on the application; for example, it can be approximately 0.05 to 30 μm.

[0070] [Step (ii)] In step (ii), the mold having the uneven pattern is pressed onto the curable film to transfer the uneven pattern to the curable film. As shown in Figure 1(B), a mold 3 having a fine uneven pattern on its surface is pressed against a substrate 1 on which a curable film 2 has been formed, facing the curable film 2. This deforms the curable film 2 to match the uneven structure of the mold 3.

[0071] The pressure applied to the curable film 2 when the mold 3 is pressed is preferably 10 MPa or less, more preferably 5 MPa or less, and particularly preferably 1 MPa or less. By pressing the mold 3 onto the curable film 2, the curable composition located on the convex parts of the mold 3 is easily pushed to the concave parts of the mold 3, and the uneven structure of the mold 3 is transferred to the curable film 2.

[0072] The uneven pattern of mold 3 can be formed, for example, by photolithography or electron beam lithography, according to the desired processing accuracy. Mold 3 is preferably a light-transmitting mold. The material of the light-transmitting mold is not particularly limited, but it should have a predetermined strength and durability. Specifically, examples include light-transmitting resin films such as glass, quartz, polymethyl methacrylate, and polycarbonate resin, transparent metal vapor-deposited films, flexible films such as polydimethylsiloxane, photocurable films, and metal films.

[0073] [Step (iii)] In step (iii), the mold is pressed onto the curable film, and the curable film on which the uneven pattern has been transferred is cured to form a resin cured film. In this embodiment, as shown in Figure 1(C), the mold 3 is pressed onto the curable film 2, and the curable film 2, onto which the uneven pattern has been transferred, is exposed to light. Specifically, electromagnetic waves such as ultraviolet (UV) light are irradiated onto the curable film 2. Due to the exposure, the curable film 2 hardens while the mold 3 is pressed, and a cured film (cured pattern) is formed with the uneven pattern of the mold 3 transferred onto it. Furthermore, mold 3 in Figure 1(C) is transparent to electromagnetic waves.

[0074] The light used to cure the curable film 2 is not particularly limited and includes, for example, light or radiation with wavelengths in the range of high-energy ionizing radiation, near-ultraviolet light, far-ultraviolet light, visible light, infrared light, etc. Suitable radiations include, for example, microwaves, EUV, LEDs, semiconductor laser light, or laser light used in semiconductor microfabrication, such as 248 nm KrF excimer laser light or 193 nm ArF excimer laser light. These lights may be monochromatic or a mixture of multiple wavelengths (mixed light).

[0075] [Step (iv)] In step (iv), the mold is peeled off the cured film. As shown in Figure 1(D), the mold 3 is peeled off the cured film. This creates a pattern 2' (cured pattern) on the substrate 1, which consists of the cured film with the transferred uneven pattern.

[0076] In the pattern formation method of this embodiment described above, a curable composition containing the above-mentioned components (X), (B), and (C) is used. By using such a curable composition, the refractive index of the cured film can be increased, and a cured film with good light resistance can be formed.

[0077] In this embodiment, a release agent may be applied to the surface 31 of the mold 3 that is in contact with the curable film 2 (Figure 1(A)). This improves the release properties between the mold and the cured film. Examples of release agents used here include silicone-based release agents, fluorine-based release agents, polyethylene-based release agents, polypropylene-based release agents, paraffin-based release agents, montan-based release agents, and carnauba-based release agents. Among these, fluorine-based release agents are preferred. For example, commercially available coating-type release agents such as Optool DSX manufactured by Daikin Industries, Ltd. can be suitably used. One type of release agent may be used alone, or two or more types may be used in combination.

[0078] Furthermore, in this embodiment, an organic layer may be provided between the substrate 1 and the curable film 2. This allows for the easy and reliable formation of a desired pattern on the substrate 1 by etching the substrate 1 using the curable film 2 and the organic layer as a mask. The thickness of the organic layer can be adjusted as appropriate according to the depth to which the substrate 1 is processed (etched), and is preferably 0.02 to 2.0 μm. The material of the organic layer is preferably one that has lower etching resistance to oxygen-based gases than the curable composition and higher etching resistance to halogen-based gases than the substrate 1. The method for forming the organic layer is not particularly limited, but examples include sputtering and spin coating.

[0079] The pattern forming method of the second embodiment may further include other steps (optional steps) in addition to steps (i) to (iv). Optional steps include an etching step (step (v)) and a step to remove the hardened film (hardened pattern) after etching (step (vi)).

[0080] [Process (v)] In step (v), for example, the substrate 1 is etched using the pattern 2' obtained in steps (i) to (iv) described above as a mask. As shown in Figure 2(E), the substrate 1 on which pattern 2' is formed is irradiated with plasma and at least one of reactive ions (indicated by arrows) to remove the portion of the substrate 1 exposed on the pattern 2' side by etching to a predetermined depth. The plasma or reactive ion gas used in process (v) is not particularly limited, as long as it is a gas commonly used in the field of dry etching.

[0081] [Process (vi)] In step (vi), the hardened film remaining after the etching process in step (v) is removed. As shown in Figure 2(F), this is a step to remove the hardened film (pattern 2') remaining on the substrate 1 after etching. The method for removing the remaining cured film (pattern 2') on the substrate 1 is not particularly limited, but examples include cleaning the substrate 1 with a solution that dissolves the cured film. [Examples]

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0083] <Preparation of curable composition> (Examples 1-3, Comparative Examples 1-3) Each curable composition was prepared by combining the components shown in Table 1.

[0084] [Table 1]

[0085] In Table 1, each abbreviation has the following meaning. The numbers in brackets [ ] represent the amount (parts by mass, solids).

[0086] • (X) Component (Niobium oxide nanoparticles) (X)-1: Niobium oxide nanoparticles, manufactured by Taki Chemical Co., Ltd., product name "Bylal Nb-G6000", aqueous solvent, concentration 6.68% by mass. Volume average primary particle size 23 nm.

[0087] • (X2) Component (metal oxide nanoparticles) (X2)-1: Titanium dioxide nanoparticles, manufactured by Ishihara Sangyo Co., Ltd., product name "LDB-014-35", PGME solvent, concentration 35% by mass. Volume average primary particle diameter 55 nm. (X2)-2: Titanium dioxide nanoparticles, manufactured by JGC Catalysts & Chemicals Co., Ltd., product name "ELECOM V-9108", PGME solvent, concentration 35% by mass. Volume average primary particle size 15 nm.

[0088] ·(B) Component (polymerizable compound) (B)-1: Polyfunctional acrylate, manufactured by Sakamoto Pharmaceutical Co., Ltd., product name "SA-TE60"; solution. (B)-2: Polyfunctional acrylate, manufactured by Nippon Kayaku Co., Ltd., product name "KAYARAD DPHA"; solution. (B)-3: Trimethylolpropane triacrylate, manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate TMP-A"; solution.

[0089] • (C) Component (polymerization initiator) (C)-1:2-Hydroxy-2-methyl-1-phenylpropanone, manufactured by IGM Resins BV, product name "Omnirad 1173". Molecular weight 164.2. (C)-2: 2,2-dimethoxy-2-phenylacetophenone, manufactured by IGM Resins BV, product name "Omnirad 651". Molecular weight 256.3.

[0090] • (E) Component (additive) (E)-1: Color separation prevention agent, manufactured by Kyoeisha Chemical Co., Ltd., product name "Florence GW-1500". (E)-2: Fluorine-based surfactant, manufactured by OMNOVA, product name "PolyFox PF656".

[0091] • (S) component (solvent component) (S)-1: High-purity pure water (DIW) (S)-2: Propylene glycol monomethyl ether (PGME)

[0092] <Rating> For each curable composition, the refractive index, lightfastness, and imprint transferability of the cured film were evaluated using the methods described below. The results are shown in Tables 2 and 3.

[0093] [Refractive index] Each curable composition from Examples 1-3 and Comparative Example 1 was spin-coated onto a silicon substrate at a spin speed of 2000 rpm. Pre-baking was then performed at 60°C for 1 minute, and then an imprinting device (ST-200) manufactured by Toshiba Machine Co., Ltd. was used to expose the substrate at an exposure of 5 J / cm². 2 A cured film with a thickness of 200 nm was obtained by photocuring treatment (under a vacuum atmosphere of 200 Pa). Furthermore, each of the curable compositions in Comparative Examples 2 and 3 was spin-coated onto a silicon substrate at a spin speed of 1000 rpm. Next, pre-baking was performed at 100°C for 1 minute, and then exposure was applied using a Toshiba Machine ST-200 imprint apparatus at an exposure of 1 J / cm². 2 A cured film with a thickness of 600 nm was obtained by photocuring treatment (under a vacuum of 200 Pa). The refractive index at a wavelength of 530 nm was measured for the cured film obtained immediately after fabrication using a JAWoollam M2000 spectroscopic ellipsometer.

[0094] [Table 2]

[0095] [Lightfastness] The following lightfastness tests were conducted. Each curable composition from Examples 1-3 and Comparative Example 1 was spin-coated onto a silicon substrate at a spin speed of 2000 rpm. Pre-baking was then performed at 60°C for 1 minute, and then an imprinting device (ST-200) manufactured by Toshiba Machine Co., Ltd. was used to expose the substrate at an exposure of 5 J / cm². 2 A cured film with a thickness of 200 nm was obtained by photocuring treatment (under a vacuum atmosphere of 200 Pa). Furthermore, each of the curable compositions in Comparative Examples 2 and 3 was spin-coated onto a silicon substrate at a spin speed of 1000 rpm. Next, pre-baking was performed at 100°C for 1 minute, and then exposure was applied using a Toshiba Machine ST-200 imprint apparatus at an exposure of 1 J / cm². 2 A cured film with a thickness of 600 nm was obtained by photocuring treatment (under a vacuum of 200 Pa). The resulting cured film was subjected to a lightfastness test using a xenon weathermeter under continuous irradiation. The test periods were 0.1 hours and 150 hours. A Suga Test Instruments XT1500 Table Sun xenon weathermeter was used. The refractive index at a wavelength of 530 nm was measured for each cured film after 0.1 hours and 150 hours of testing, using a JAWoollam M2000 spectroscopic ellipsometer. The measured refractive indices were defined as the refractive index after 0.1 hours and the refractive index after 150 hours of lightfastness testing, respectively. Then, the difference between the refractive index after 0.1 hours of the lightfastness test and the refractive index after 150 hours of the lightfastness test was calculated, and the lightfastness was evaluated according to the evaluation criteria below. Evaluation Criteria ◎: Difference in refractive index is less than 0.05 ○: The difference in refractive index is 0.05 or more and less than 0.15. ×: The difference in refractive index is 0.15 or greater.

[0096] [Table 3]

[0097] [Imprint transferability] The imprint transfer properties of each curable composition in Example 3 and Comparative Example 1 were evaluated.

[0098] The curable composition of Example 3 was spin-coated onto a silicon substrate at a spin speed of 2000 rpm. Pre-baking was then performed at 60°C for 1 minute, and then an imprinting device, the ST-200, manufactured by Toshiba Machine Co., Ltd., was used with a pressing condition of 0.5 kN for 150 seconds and an exposure dose of 5 J / cm². 2 Transfer tests were conducted under a vacuum of 200 Pa to evaluate the transferability and packing properties of the fine patterns. The mold used was the standard film mold LSP70-140 (70nm Line & Space) manufactured by Soken Chemical Co., Ltd.

[0099] The results of the evaluation of the imprint transfer properties showed that when the curable composition of Example 3 was used, both the transferability and filling ability of the fine pattern were good.

[0100] For the curable composition of Comparative Example 1, a transfer test was performed in the same manner as when using the curable composition of Example 3, except that the pressing conditions were changed to 8.0 kN for 150 seconds. The transferability and filling ability of the fine pattern were evaluated. As a result, when the curable composition of Comparative Example 1 was used, filling was possible, but some parts of the pattern shape were defective.

[0101] From the above evaluation results, it was confirmed that the curable composition of the example to which the present invention is applied can increase the refractive index and form a cured film with good light resistance. Furthermore, the curable compositions of the examples to which the present invention was applied exhibited good pattern transfer properties and were confirmed to be suitable materials for photoimprint lithography. [Explanation of symbols]

[0102] 1. Substrate, 2. Curable film, 3. Mold

Claims

1. It contains (X) component: niobium oxide nanoparticles, (B) component: polymerizable compound, and (C) component: polymerization initiator. With respect to 100 parts by mass of the total content of component (X) and component (B), The content of component (X) is 25 to 70 parts by mass, A curable composition for photoimprint lithography, wherein the content of component (B) is 30 to 75 parts by mass.

2. The curable composition for photoimprint lithography according to claim 1, wherein component (C) is a photoradical polymerization initiator.

3. The curable composition for photoimprint lithography according to claim 1, wherein the volume-average primary particle diameter of component (X) is 40 nm or less.

4. The curable composition for photoimprint lithography according to claim 1, wherein component (B) comprises a polymerizable compound having three or more polymerizable functional groups.

5. The curable composition for photoimprint lithography according to claim 1, wherein component (B) comprises a monomer having five or more polymerizable functional groups.

6. A step of forming a curable film on a substrate using a curable composition for photoimprint lithography according to any one of claims 1 to 5, A step of pressing a mold having an uneven pattern onto the curable film to transfer the uneven pattern onto the curable film, The process of forming a cured film by pressing the mold onto the curable film and curing the curable film onto which the uneven pattern has been transferred, A step of peeling the mold from the cured film, A pattern forming method having the following characteristics.

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