Photocurable composition, pattern forming method, and cured film

Abstract

A photocurable composition that contains metal oxide nanoparticles (X) and a photopolymerizable sulfur compound (C).

Description

[Technical Field]

[0001] The present invention relates to a photocurable composition and a pattern forming method. This application claims priority based on Japanese Patent Application No. 2021-042612, filed in Japan on March 16, 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.

[0006] One known method for increasing the refractive index of nanoimprint materials is to add metal oxide nanoparticles. For example, Patent Document 1 describes a photocurable resin composition in which the refractive index is increased by incorporating metal oxide nanoparticles such as titanium dioxide or zirconium oxide.

[0007] Furthermore, as a means of increasing the refractive index of nanoimprint materials, for example, Patent Document 2 describes a photocurable resin composition in which the refractive index is increased by using a compound having a biphenyl skeleton and polymerizable groups, and a photopolymerization initiator. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2013-191800 [Patent Document 2] Japanese Patent Publication No. 2013-95833 [Overview of the project] [Problems that the invention aims to solve]

[0009] To further increase the refractive index of nanoimprint materials, it has been considered to increase the content of metal oxide nanoparticles or increase the particle size of the metal oxide nanoparticles. However, there is a problem that excessive addition of metal oxide nanoparticles increases the viscosity of the photocurable resin composition, degrading the packing ability of the nanoimprint pattern. Furthermore, as a result of our investigations, we found that when a compound having a biphenyl skeleton and polymerizable groups, as described in Patent Document 2, is used, the packing performance of the nanoimprint pattern tends to deteriorate. The present invention has been made in view of the above circumstances, and aims to provide a photocurable composition and a pattern forming method that have a high refractive index and good transferability of fine patterns. [Means for solving the problem]

[0010] To solve the above problems, the present invention employs the following configuration. In other words, a first aspect of the present invention is a photocurable composition containing metal oxide nanoparticles (X) and a photopolymerizable sulfur compound (C).

[0011] A second aspect of the present invention is a pattern forming method comprising the steps of: forming a photocurable film on a substrate using a photocurable composition according to the first aspect; pressing a mold having an uneven pattern onto the photocurable film to transfer the uneven pattern to the photocurable film; pressing the mold onto the photocurable film while exposing the photocurable film on which the uneven pattern has been transferred to form a cured film; and peeling the mold from the cured film. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a photocurable composition with a high refractive index and good transferability of fine patterns, and a pattern forming method. [Brief explanation of the drawing]

[0013] [Figure 1] It is a schematic process diagram for explaining one embodiment of a nanoimprint pattern formation method. [Figure 2] It is a schematic process diagram for explaining an example of an arbitrary process.

Mode for Carrying Out the Invention

[0014] In this specification and the claims of the present 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 the 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 irradiation with radiation in general.

[0015] (Photocurable composition) The photocurable composition of the first aspect of the present invention contains metal oxide nanoparticles (X) and a photopolymerizable sulfur compound (C).

[0016] <(X) component> (X) component is metal oxide nanoparticles. "Nanoparticle" means a particle having a volume average primary particle diameter on the order of nanometers (less than 1000 nm). Metal oxide nanoparticles are metal oxide particles having an average primary particle diameter on the order of nanometers.

[0017] The volume-average primary particle diameter of component (X) is preferably 100 nm or less. The volume-average primary particle diameter of component (X) is preferably 0.1 to 100 nm, more preferably 1 to 60 nm, even more preferably 1 to 50 nm, even more preferably 1 to 45 nm, and particularly preferably 1 to 40 nm. The volume-average primary particle diameter of component (X) is even more preferably 5 to 30 nm, 5 to 25 nm, or 5 to 30 nm. When the volume-average primary particle diameter of the metal nanoparticles of component (X) is within the above preferred range, the metal oxide nanoparticles are well dispersed in the photocurable composition. Furthermore, the refractive index is good. The volume-average primary particle diameter is a value measured by dynamic light scattering.

[0018] As component (X), commercially available metal oxide nanoparticles can be used. Examples of metal oxides include oxide particles of titanium (Ti), zirconium (Zr), aluminum (Al), silicon (Si), zinc (Zn), or magnesium (Mg). Among these, titania (TiO2) nanoparticles or zirconia (ZrO2) nanoparticles are preferred as component (X) from the viewpoint of refractive index.

[0019] In this embodiment, commercially available metal oxide nanoparticles can be used as component (X). Examples of commercially available titania nanoparticles include the TTO series (TTO-51(A), TTO-51(C), etc.) and 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.) manufactured by Teika Co., Ltd., ELECOM V-9108 manufactured by Nikkei Shokubai Kasei Co., Ltd., and STR-100A-LP manufactured by Sakai Kagaku Kogyo Co., Ltd. Examples of commercially available zirconia nanoparticles include UEP (manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd.), PCS (manufactured by Nippon Denko Co., Ltd.), JS-01, JS-03, JS-04 (manufactured by Nippon Denko Co., Ltd.), and UEP-100 (manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd.).

[0020] In the photocurable composition of this embodiment, component (X) may be used alone or in combination of two or more types.

[0021] The content of component (X) in the photocurable composition of this embodiment can be 60 to 99 parts by mass per 100 parts by mass of the total of component (X) and component (C) described later. The content of component (X) in the photocurable composition of this embodiment is preferably 65 to 95 parts by mass, more preferably 65 to 90 parts by mass, even more preferably 65 to 80 parts by mass, and particularly preferably 65 to 75 parts by mass per 100 parts by mass of the total of component (X) and component (C) described later. If the content of component (X) is above the lower limit of the preferred range described above, the optical properties of the cured film formed using the photocurable composition will be better. On the other hand, if the content of component (X) is below the upper limit of the preferred range described above, the photocurable composition will have good mold-filling properties.

[0022] Furthermore, if the photocurable composition of this embodiment contains component (B) described later, the content of component (X) can be 10 to 99 parts by mass per 100 parts by mass of the total of component (X), component (C) described later, and component (B) described later. The content of component (X) in the photocurable composition of this embodiment is preferably 60 to 90 parts by mass, more preferably 60 to 85 parts by mass, even more preferably 60 to 80 parts by mass, and particularly preferably 60 to 75 parts by mass per 100 parts by mass of the total of component (X) and component (C) described later. If the content of component (X) is above the lower limit of the preferred range described above, the optical properties of the cured film formed using the photocurable composition will be better. On the other hand, if the content of component (X) is below the upper limit of the preferred range described above, the photocurable composition will have good mold-filling properties.

[0023] <(C) component> (C) component is a photopolymerizable sulfur compound. The "photopolymerizable sulfur compound" is a photopolymerizable monomer containing a sulfur atom in the molecule. That is, the photopolymerizable sulfur compound is a monomer containing a sulfur atom and having a polymerizable functional group.

[0024] Examples of the (C) component include compounds having a diaryl sulfide skeleton (hereinafter also referred to as "(C1) component"). Examples of the (C1) component include compounds represented by the following general formula (c-1).

[0025] [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.]

[0026] In the formula (c-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 the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like. Examples of the branched alkyl group include an isopropyl group, a sec-butyl group, a tert-butyl group and the like. Among them, the alkyl group is preferably a methyl group or an ethyl group, and more preferably a methyl group.

[0027] The R 11 ~R 14 and R21 ~R 24 Examples of halogen atoms in this compound include fluorine, chlorine, bromine, and iodine atoms. Chlorine atoms are preferred as the halogen atom.

[0028] 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.

[0029] In the above equation (c-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 polymerizable groups, with acryloyl groups and methacryloyl groups being more preferred. R 5 The group is preferably an acryloyl group or a methacryloyl group.

[0030] Examples of component (C) include bis(4-methacryloylthiophenyl) sulfide and bis(4-acryloylthiophenyl) sulfide. Among these, bis(4-methacryloylthiophenyl) sulfide is preferred as component (C).

[0031] In the photocurable composition of this embodiment, component (C) may be used alone or in combination of two or more types.

[0032] The content of component (C) can be 1 to 40 parts by mass per 100 parts by mass of the total of component (X) and component (C). Preferably, the content of component (C) is 1 to 35 parts by mass, more preferably 5 to 35 parts by mass, even more preferably 10 to 35 parts by mass, even more preferably 20 to 35 parts by mass, and particularly preferably 25 to 35 parts by mass per 100 parts by mass of the total of component (X) and component (C). If the content of component (C) is above the lower limit of the preferred range described above, the refractive index of the cured film formed using the photocurable composition is further improved. On the other hand, if the content of component (C) is below the upper limit of the preferred range described above, the dispersibility of component (X) in the photocurable composition is good.

[0033] Furthermore, if the photocurable composition of this embodiment contains component (B) described later, the content of component (C) is preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, even more preferably 5 to 25 parts by mass, even more preferably 5 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, based on 100 parts by mass of the total of components (X), (C), and (B). If the content of component (C) is above the lower limit of the preferred range described above, the refractive index of the cured film formed using the photocurable composition is further improved. On the other hand, if the content of component (C) is below the upper limit of the preferred range described above, the dispersibility of component (X) in the photocurable composition is good.

[0034] <Optional ingredients> The photocurable composition of this embodiment may contain other components in addition to components (X) and (C). Optional components include, for example, a photopolymerizable monomer having polymerizable functional groups other than component (C) (component (B)), a photopolymerization initiator (component (D)), a solvent (component (S)), and miscible additives (e.g., degradation inhibitors, mold release agents, diluents, antioxidants, heat stabilizers, flame retardants, plasticizers, surfactants, and other additives to improve the properties of the cured film).

[0035] <(B) component> Component (B) is a photopolymerizable monomer having polymerizable functional groups other than those of component (C). A "polymerizable functional group" is a group that enables compounds to polymerize through radical polymerization or other means, and includes, for example, groups containing multiple bonds between carbon atoms, such as ethylenic double bonds. When the photocurable composition of this embodiment contains component (B), the crosslinking properties are improved, and properties such as heat resistance tend to improve.

[0036] 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.

[0037] Examples of photopolymerizable monomers (monofunctional monomers) having one polymerizable functional group include (meth)acrylates containing aliphatic polycyclic structures such as isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, bornyl (meth)acrylate, and tricyclodecanyl (meth)acrylate (hereinafter referred to as "component (B1)"); (meth)acrylates containing aliphatic monocyclic structures such as dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, and acryloylmorpholine; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. (Meth)acrylates containing chain-like structures such as methyl (meth)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, and isostearyl (meth)acrylate;(Meth)acrylates containing aromatic ring structures such as 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)acrylate, 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, etc. (hereinafter referred to as "component (B2)"); tetrahydrof Examples include lefuryl (meth)acrylate, butoxyethyl (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; and terminally methacrylatesiloxane monomers.

[0038] Examples of commercially available monofunctional monomers include Aronix 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 (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 Kojin Co., Ltd.); X-22-2404 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

[0039] Examples of photopolymerizable monomers (bifunctional 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, and bis(hydroxymethyl)tricyclodecane di(meth)acrylate.

[0040] Examples of commercially available difunctional monomers include light acrylates 3EG-A, 4EG-A, 9EG-A, NP-A, DCP-A, BP-4EAL, and BP-4PA (all manufactured by Kyoeisha Chemical Co., Ltd.).

[0041] Examples of photopolymerizable compounds having three or more polymerizable functional groups include photopolymerizable siloxane compounds, photopolymerizable silsesquioxane compounds, and polyfunctional monomers having three or more polymerizable functional groups.

[0042] Examples of photopolymerizable siloxane compounds include compounds having both an alkoxysilyl group and a polymerizable functional group within the molecule. Examples of commercially available photopolymerizable siloxane compounds include the products "KR-513," "X-40-9296," "KR-511," "X-12-1048," and "X-12-1050" manufactured by Shin-Etsu Chemical Co., Ltd.

[0043] Photopolymerizable 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, photopolymerizable silsesquioxane compounds have three or more polymerizable functional groups. Examples of polymerizable functional groups include vinyl groups, allyl groups, methacryloyl groups, and acryloyl groups.

[0044] 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.

[0045] Examples of commercially available photopolymerizable silsesquioxane compounds include "MAC-SQ LP-35," "MAC-SQ TM-100," "MAC-SQ SI-20," and "MAC-SQ HDM," all manufactured by Toagosei Co., Ltd.

[0046] 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.

[0047] Examples of commercially available polyfunctional monomers include "A-9300-1CL," "AD-TMP," "A-9550," and "A-DPH" from Shin Nakamura Chemical Industry Co., Ltd., "KAYARAD DPHA" from Nippon Kayaku Co., Ltd., and "Light Acrylate TMP-A" from Kyoeisha Chemical Co., Ltd.

[0048] The content of component (B) can be 5 to 80 parts by mass per 100 parts by mass of the total of component (X), component (C), and component (B). The content of component (B) is preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass, even more preferably 10 to 30 parts by mass, and particularly preferably 10 to 25 parts by mass per 100 parts by mass of the total of component (X) and component (B). If the content of component (B) is above the lower limit of the preferred range described above, the curability and fluidity of the resin cured film formed using the photocurable composition will be good. On the other hand, if the content of component (B) is below the upper limit of the preferred range described above, the dispersibility of component (X) in the photocurable composition will be good.

[0049] <(D) component> Component (D) is a photopolymerization initiator. Component (D) is a compound that initiates or promotes the polymerization of component (B) upon exposure. A photoradical polymerization initiator is preferred as component (D).

[0050] (D) Examples of components include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 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, 2,2-dimethoxy-1,2-diphenylethane-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-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate 4-Dimethylaminobenzoate butyl, 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 benzoylbenzoate, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 1-chloro-4-propoxythioxanthone, thioxanthene, 2-chlorothioxanthene, 2,4-diethyl Thioxanthene, 2-methylthioxanthene, 2-isopropylthioxanthene, 2-ethylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-diphenylanthraquinone, azobisisobutyronitrile, benzoyl peroxide, cumene 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-Diethoxyacetophenone, p-Dimethylacetophenone, p-Dimethylaminopropiophenone, Dichloroacetophenone Phenone, 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-phenylacridin, 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)-s-triazine, 2-[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, and cyclohexanone peroxide; Diacyl peroxides such as isobutyryl peroxide and bis(3,5,5-trimethylhexanoyl) peroxide; p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide Examples include hydroperoxides such as said; dialkylperoxides 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-propylperoxydicarbonate and diisopropylperoxydicarbonate; and azo compounds such as azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobisisobutyrate.

[0051] Among the above, 1-hydroxycyclohexylphenyl ketone, 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.

[0052] (D) For component (D), commercially available products can be used. Examples of commercially available products containing component (D) include BASF's "IRGACURE 907," "IRGACURE 369," and "IRGACURE 819," as well as products from IGM Resins BV, such as "Omnirad 184," "Omnirad 651," "Omnirad 819," and "Omnirad 184."

[0053] (D) Component is preferably small in molecular weight. A smaller molecular weight of (D) component tends to reduce haze further. The molecular weight of (D) 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 (D) component is not particularly limited, but examples include 100 or more, 150 or more, or 200 or more. The molecular weight of (D) 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.

[0054] In the photocurable composition of this embodiment, component (D) may be used alone or in combination of two or more types.

[0055] In the photocurable composition of this embodiment, the content of component (D) 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 of components (X), (C), and (B). By keeping the content within the above range, the photocurability is further improved when the content of component (D) is within the above preferred range.

[0056] ≪Solvent: (S) component≫ The photocurable 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), (C), and any desired components.

[0057] (S) components include, for example, 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 hexanemethanol, 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 photocurable composition of this embodiment, component (S) may be used alone or in combination of two or more types. Among the above, the (S) component is preferably at least one selected from the group consisting of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME).

[0059] The amount of component (S) used is not particularly limited and can be set appropriately according to the coating thickness of the photocurable composition. For example, it can be used in an amount of about 100 to 500 parts by mass relative to 100 parts by mass of the total of component (X) and component (B).

[0060] <<Surfactants: (E) component>> The photocurable 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 photocurable composition of this embodiment, one surfactant may be used alone, or two or more surfactants may be used in combination. If the photocurable 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 of component (X) and component (B). When the surfactant content is within the aforementioned preferred range, the photocurable composition exhibits good coatability.

[0062] The cured film formed by the photocurable composition of this embodiment typically has a refractive index of 1.86 or higher at a wavelength of 530 nm. Because the photocurable composition of this embodiment can form a cured film with such a high refractive index while maintaining good pattern transferability, 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 photocurable composition of this embodiment described above contains component (X) and component (C). Component (C) contains sulfur. The carbon-sulfur bond (CS bond) in component (C) is polarized and is presumed to function as a binder for component (X), resulting in good dispersibility of component (X) in the photocurable composition. Therefore, it is presumed that the photocurable composition of this embodiment will produce a resin-cured film with excellent optical properties (high refractive index, haze, etc.) and good pattern transferability.

[0064] Such photocurable compositions are useful as materials for forming fine patterns on substrates using imprint technology, and are particularly suitable for photoimprint lithography. They offer advantageous effects in applications requiring high refractive indices, such as 3D sensors for autonomous driving and AR waveguides for augmented reality (AR) glasses. Furthermore, the photocurable composition of this embodiment is also useful as a material for, for example, an anti-reflective coating.

[0065] (Pattern formation method) A pattern forming method according to a second aspect of the present invention comprises the steps of: forming a photocurable film on a substrate using the photocurable composition of the first aspect described above (hereinafter referred to as "step (i)"); pressing a mold having an uneven pattern onto the photocurable film to transfer the uneven pattern onto the photocurable film (hereinafter referred to as "step (ii)"); pressing the mold onto the photocurable film while exposing the photocurable film on which the uneven pattern has been transferred to 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 photocurable film is formed on the substrate using the photocurable composition of the first embodiment described above. As shown in Figure 1(A), the photocurable composition according to the first embodiment described above is applied to the substrate 1 to form a photocurable film 2. In Figure 1(A), the mold 3 is positioned above the photocurable 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-non-transmitting.

[0069] Methods for applying the photocurable composition to the substrate 1 include spin coating, spray coating, inkjet coating, roll coating, and rotary coating. Since the photocurable film 2 functions as a mask in an etching process of the substrate 1 that may be performed afterward, it is preferable that the film thickness when applied to the substrate 1 is uniform. From this point of view, the spin coating method is preferred when applying the photocurable composition to the substrate 1. The thickness of the photocurable 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), a mold having an uneven pattern is pressed onto the photocurable film to transfer the uneven pattern to the photocurable 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 photocurable film 2 has been formed, facing the photocurable film 2. This deforms the photocurable film 2 to match the uneven structure of the mold 3.

[0071] The pressure applied to the photocurable 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 photocurable film 2, the photocurable 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 photocurable 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 photocurable film, and the photocurable film on which the uneven pattern has been transferred is exposed to light to form a resin-cured film. As shown in Figure 1(C), the photocurable film 2, onto which the uneven pattern has been transferred, is exposed to light while the mold 3 is pressed against it. Specifically, electromagnetic waves such as ultraviolet (UV) light are irradiated onto the photocurable film 2. Upon exposure, the photocurable film 2 hardens while the mold 3 is pressed against it, forming a hardened film (hardened pattern) onto which the uneven pattern of the mold 3 has been transferred. Note that the mold 3 in Figure 1(C) is transparent to electromagnetic waves.

[0074] The light used to cure the photocurable 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 photocurable composition containing the above-mentioned components (X), (T), (B), and (C) is used. By using such a photocurable composition, it is possible to form a pattern with a high refractive index and excellent light resistance.

[0077] In this embodiment, a release agent may be applied to the surface 31 of the mold 3 that is in contact with the photocurable 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] In this embodiment, an organic layer may be provided between the substrate 1 and the photocurable film 2. This allows for the simple and reliable formation of a desired pattern on the substrate 1 by etching the substrate 1 using the photocurable film 2 and the organic layer as masks. The thickness of the organic layer can be appropriately adjusted 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 photocurable 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 photocurable compositions> Each example of a photocurable composition was prepared by combining the components shown in Tables 1 and 2.

[0084] [Table 1]

[0085] [Table 2]

[0086] In Tables 1 and 2, each abbreviation has the following meaning. The numbers in brackets [ ] represent the amount (parts by mass) of the ingredients.

[0087] • Component (X) (metal oxide nanoparticles) (X)-1: Titania particles, manufactured by Teika Corporation, product name "NS405". Volume average primary particle diameter 15 nm. (X)-2: Titania particles, manufactured by Ishihara Sangyo Co., Ltd., product name "LDB-014-35". Volume average primary particle diameter 15 nm. (X)-3: Zirconia particles, manufactured by Daiichi Rare Elements Chemical Industry Co., Ltd., product name "UEP-100". Volume average primary particle diameter 15 nm.

[0088] • (B) Component (photopolymerizable monomer) (B)-1: Polyfunctional acrylate, manufactured by Nippon Kayaku Co., Ltd., product name "KAYARAD DPHA". (B)-2: Trimethylolpropane triacrylate, manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate TMP-A".

[0089] ·(C)Component (photopolymerizable sulfur compound) (C)-1: Bis(4-methacryloylthiophenyl) sulfide, manufactured by Tokyo Chemical Industry Co., Ltd.

[0090] [ka]

[0091] ·(Z) component (photopolymerizable aromatic compound) (Z)-1: Bisphenol A type epoxy acrylate, manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name "NK Oligo EA-1010NT2".

[0092] (Z)-2: p-phenylbenzyl acrylate, manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name "NK Ester A-BPML".

[0093] • (D) Component (Photopolymerization Initiator) (D)-1: 2,2-dimethoxy-2-phenylacetophenone, manufactured by IGM Resins BV, product name "Omnirad 651". Molecular weight 256.3.

[0094] ·(E) Component (E)-1: Fluorine-based surfactant, manufactured by OMNOVA, product name "PolyFox PF656".

[0095] • (S) component (solvent) (S)-1: Propylene glycol monomethyl ether acetate (PGMEA). (S)-2: Propylene glycol monomethyl ether (PGME).

[0096] <Rating> For each example of a photocurable composition, the imprint transferability, refractive index, and haze were evaluated using the methods described below. These results are shown in Tables 3-4.

[0097] [Imprint transferability] A photocurable composition was prepared to a film thickness of 600 nm and applied by spin coating onto a silicon substrate. Pre-baking was then performed at 100°C for 1 minute. Finally, using a Toshiba Machine ST-200 imprint apparatus, the transfer was performed with a transfer pressure of 0.5 MPa, a transfer time of 30 seconds, and an exposure dose of 1 J / cm². 2 Transfer tests were conducted under a 200 Pa vacuum atmosphere, and the transferability and filling performance of the fine patterns were evaluated according to the following criteria. The mold used was the standard film mold LSP70-140 (70nm Line & Space) manufactured by Soken Chemical Co., Ltd. Good: 95% or higher (When confirmed by SEM, the mold is 100% filled and the pattern has been transferred.) Defective: Less than 95%

[0098] [Refractive index] A photocurable composition was prepared to a film thickness of 600 nm and then spin-coated onto a silicon substrate. Next, pre-baking was performed at 100°C for 1 minute, and then exposure was applied using a Toshiba Machine ST-200 imprint scanner at an exposure dose of 1 J / cm². 2 A cured film was obtained by photocuring under a vacuum of 200 Pa. The refractive index of the obtained cured film at a wavelength of 530 nm was measured using a JAWoollam M2000 spectroscopic ellipsometer.

[0099] [Table 3]

[0100] [Table 4]

[0101] From the results in Tables 3-4, the photocurable compositions in Examples 1-13 to which the present invention was applied exhibited good imprintability and had a high refractive index of 1.86 or higher. On the other hand, the photocurable compositions in Comparative Examples 1, 3-5, 11 and 12 exhibited good imprintability, but had a refractive index of 1.85 or lower. Furthermore, the photocurable compositions in Comparative Examples 2, 6-10 and 13-15 had a refractive index of 1.86 or higher, but exhibited poor imprintability. These results confirm that the photocurable compositions in the examples yield resin-cured films with good imprintability and a high refractive index.

[0102] While preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the invention. The present invention is not limited by the foregoing description, but only by the scope of the appended claims. [Explanation of symbols]

[0103] 1. Substrate, 2. Photocurable film, 3. Mold

Claims

1. Metal oxide nanoparticles (X) and Photopolymerizable sulfur compounds (C) and It contains, The aforementioned metal oxide nanoparticles (X) are titania (TiO2). ２ ) These are nanoparticles, The aforementioned photopolymerizable sulfur compound (C) is a compound represented by the following general formula (c-1), The total content of the metal oxide nanoparticles (X) and the photopolymerizable sulfur compound (C) is 100 parts by mass, and the content of the photopolymerizable sulfur compound (C) is 10 to 40 parts by mass. A photocurable composition for photoimprint lithography that does not contain a photopolymerizable monomer having a polymerizable functional group other than the aforementioned photopolymerizable sulfur compound (C). 【Chemistry 1】 [In the formula, R １１ ~R １４ and R ２１ ~R ２４ Each of these independently represents a hydrogen atom, an alkyl group, or a halogen atom, and R ５ This represents a polymerizable functional group.

2. The photocurable composition for photoimprint lithography according to claim 1, wherein the volume-average primary particle diameter of the metal oxide nanoparticles (X) is 100 nm or less.

3. The photocurable composition for photoimprint lithography according to claim 1 or 2, wherein the content of the photopolymerizable sulfur compound (C) is 20 to 40 parts by mass per 100 parts by mass of the total content of the metal oxide nanoparticles (X) and the photopolymerizable sulfur compound (C).

4. The photocurable composition for photoimprint lithography according to any one of claims 1 to 3, wherein the resin cured film formed using the photocurable composition for photoimprint lithography has a refractive index of 1.86 or more at a wavelength of 530 nm.

5. A step of forming a photocurable film on a substrate using a photocurable composition for photoimprint lithography described in any one of claims 1 to 4, A step of pressing a mold having an uneven pattern onto the photocurable film to transfer the uneven pattern onto the photocurable film, The process involves pressing the mold onto the photocurable film while exposing the photocurable film on which the uneven pattern has been transferred to the mold to form a cured film, A step of peeling the mold from the cured film, A pattern forming method having the following characteristics.

6. A cured film obtained by curing a photocurable composition for photoimprint lithography according to any one of claims 1 to 4.

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