JP2020203979A - Photocurable composition - Google Patents

Abstract

To provide a photocurable composition which has a highly precise fine pattern and is excellent in etching resistance.SOLUTION: The photocurable composition contains the following components (A), (B), (C) and (D): (A) a compound represented by formula (a) and having a molecular weight of 200 or less; (B) a compound represented by formula (b); (C) a polyfunctional cationically curable compound having a number average molecular weight of 400 or more; and (D) a photocationic polymerization initiator. The content of the component (A) is 20-50 wt.% of the total content of the component (A), the component (B) and the component (C). The weight ratio (A/B) of the content of the component (A) to the content of the component (B) is 35/65-70/30.SELECTED DRAWING: None

Description

The present invention relates to a photocurable composition and a method for producing an optical device using the photocurable composition.

In the imprint method, a coating film of a photocurable composition is provided on a substrate, a mold having a fine pattern is pressed on the coating film to transfer the fine pattern, and then the coating film is cured by light irradiation. This is a method of producing a fine pattern on a substrate by obtaining a cured product having a fine pattern and dry-etching the substrate using the obtained cured product as a mask.

Then, in order to manufacture a high-precision optical device with good yield and low cost by the nanoimprint method, it is required that the mold can be used repeatedly and the mask can be formed accurately even if the mold is used many times. Be done.

However, when a silicone mold is used as the mold, the low molecular weight component in the photocurable composition easily infiltrates the silicone mold, and when the photocurable composition infiltrates the silicone mold, the thickness of the obtained cured product increases. It is thinned and the pattern is smaller than designed. When a cured product having a low pattern accuracy thus obtained is used as an etching mask, there is a problem that it becomes difficult to form a pattern on a substrate with high accuracy (for example, Non-Patent Document 1).

Microelectronic Engineering 98 (2012) 275-278

As a method of preventing the pattern accuracy of the obtained cured product from being lowered due to the infiltration of the photocurable composition into the silicone mold, the coating film of the photocurable composition was designed in anticipation of infiltration into the mold. It is possible to form it thicker. However, the ease of infiltration into the mold changes depending on the number of times the mold is used, and the infiltration is remarkable at the initial stage of repeated use, but it becomes difficult to infiltrate when saturation is reached thereafter. Therefore, it is extremely difficult to appropriately fine-tune the thickness of the coating film each time, and there is a problem that workability is significantly reduced.

Further, in order to make the pattern of the cured product finer, it is necessary to add a low molecular weight component to some extent in the photocurable composition, but since the low molecular weight component easily infiltrates into the silicone mold, it is even more It was found that the pattern accuracy of the obtained cured product tends to decrease. It was also found that even when the photocurable composition was cured, some of the low molecular weight components remained without being sufficiently crosslinked, so that the etching resistance of the obtained cured product was lowered.

Therefore, an object of the present invention is to imprint a silicone mold to form a cured product having a highly accurate fine pattern and excellent etching resistance regardless of the number of times the silicone mold has been used, easily and with good yield. To provide a photocurable composition that can be made.
Another object of the present invention is to provide a photocurable composition capable of forming an etching mask with high accuracy and at low cost.
Another object of the present invention is to etch a substrate by using a cured product having a fine pattern formed by the photocurable composition as an etching mask (hereinafter, may be simply referred to as "mask"). It is an object of the present invention to provide a method for manufacturing a characteristic optical device.

As a result of diligent studies by the present inventors to solve the above problems,
1. 1. Although the following component (A) is a low molecular weight cationic curable compound, it has high etching resistance, and when used together with the following component (B), it is difficult to infiltrate into a silicone mold. Therefore, a photocurable composition containing this is used. Infiltration into the silicone mold is suppressed, and a high-precision fine pattern can be easily and yielded well regardless of the number of times the silicone mold has been used.
2. 2. The following component (B) is difficult to infiltrate into the silicone mold, and the primary hydroxyl group in the component (B) exhibits a chain transfer reaction during curing. Therefore, a photocurable composition containing this undergoes a cationic polymerization reaction. The effect of accelerating and suppressing the residual unreacted monomer is obtained, and the pattern accuracy and etching resistance of the obtained cured product are enhanced.
3. 3. A photocurable compound containing a high-molecular-weight cationically curable compound (C) and a photocationic polymerization initiator (D) together with the following components (A) and (B) is difficult to infiltrate into a silicone mold and has excellent curability. By the imprint method, it has a high-precision fine pattern, has excellent etching resistance, and can produce a cured product.
I found it. The present invention has been completed based on these findings.

（式中、環Ｚは、−ＮＨ−基を含む複素環式芳香族化合物の構造式から、前記−ＮＨ−基の水素原子を除いた構造を示す）
成分（Ｂ）：下記式（ｂ）で表される化合物

（式中、Ｌは単結合、２価の炭化水素基、又は２個以上の炭化水素基が連結基を介して結合してなる２価の基を示し、Ｒ¹はＣＨ₂ＯＨ基、又はカチオン重合性基を示す）
成分（Ｃ）：数平均分子量（ＧＰＣによる、ポリスチレン換算）が４００以上の多官能カチオン硬化性化合物（成分（Ｂ）に含まれる化合物を除く）
成分（Ｄ）：光カチオン重合開始剤 That is, the present invention includes the following components (A), component (B), component (C), and component (D).
The content of the component (A) is 20 to 50% by weight of the total content of the component (A), the component (B), and the component (C).
Provided is a photocurable composition in which the weight ratio (A / B) of the content of the component (A) to the component (B) is 35/65 to 70/30.
Component (A): A compound represented by the following formula (a) and having a molecular weight of 200 or less.

(In the formula, ring Z indicates a structure obtained by removing the hydrogen atom of the -NH- group from the structural formula of the heterocyclic aromatic compound containing a -NH- group).
Component (B): Compound represented by the following formula (b)

(In the formula, L represents a single bond, a divalent hydrocarbon group, or a divalent group formed by bonding two or more hydrocarbon groups via a linking group, and R ¹ is a CH ₂ OH group or a CH ₂ OH group. Shows cationically polymerizable groups)
Component (C): Polyfunctional cationic curable compound having a number average molecular weight (in terms of polystyrene by GPC) of 400 or more (excluding the compound contained in the component (B))
Component (D): Photocationic polymerization initiator

The present invention also provides the photocurable composition in which the component (A) is a compound represented by the following formula (a').

The present invention also provides the photocurable composition in which the component (C) is a polyfunctional cationic curable compound having a functional group equivalent of 100 to 400 g / eq.

The present invention also provides the photocurable composition in which the weight ratio (A / C) of the content of the component (A) to the content of the component (C) is 45/55 to 25/75.

The present invention also relates to the above-mentioned light in which the weight ratio [A / (B + C)] of the content of the component (A) to the total content of the component (B) and the component (C) is 25/75 to 45/55. A curable composition is provided.

The present invention also provides the photocurable composition containing 1 to 10 parts by weight of the component (D) with respect to a total of 100 parts by weight of the component (A), the component (B), and the component (C). To do.

The present invention also comprises the photocurable composition containing 0.1 to 5 parts by weight of a surface conditioner with respect to a total of 100 parts by weight of the component (A), the component (B), and the component (C). provide.

The present invention also provides the photocurable composition comprising a solvent having a boiling point of 100 ° C. to 210 ° C. (760 mmHg).

The present invention also provides the photocurable composition for imprinting.

The present invention also provides the photocurable composition for forming an etching mask.

In the present invention, the coating film of the photocurable composition is imprinted to form a cured product having a pattern shape, and the cured product is used as a mask to etch a substrate to perform an optical device. Provided is a method for manufacturing an optical device.

Since the photocurable composition of the present invention has the above-mentioned structure, it has a property of being difficult to infiltrate into the silicone mold. Therefore, if the photocurable composition of the present invention is used, a cured product having a certain thickness can be stably formed depending on the number of times the silicone mold is used, without changing the thickness of the coating film.
Therefore, if the photocurable composition of the present invention is used, the silicone mold can be used repeatedly, and even if the silicone mold is used repeatedly, the workability is not deteriorated and the cured product has a highly accurate fine pattern. Can be manufactured with good yield. Therefore, it contributes to cost reduction and reduction of environmental load.
Further, the photocurable composition of the present invention has excellent curability, and the obtained cured product has excellent etching resistance.
Further, since the photocurable composition of the present invention contains the low molecular weight component (A) in a specific ratio, it has excellent etching resistance as described above, and further refines the pattern of the cured product. can do.

Since the photocurable composition of the present invention has the above-mentioned characteristics, the surface of a substrate (for example, a sapphire substrate) is etched by using a cured product having a fine pattern obtained by imprinting the same as a mask. For example, it is possible to manufacture a substrate (for example, PSS (Patterned Sapphire Substrate)) on which a high-precision fine pattern is formed on the surface.
By using a substrate on which the fine pattern is formed on the surface, it is possible to manufacture a flat panel display having excellent light extraction efficiency, high brightness, long life, low power consumption, low heat generation, and the like. ..

[Photocurable composition]
The photocurable composition of the present invention contains the following components (A), component (B), component (C), and component (D).
Component (A): Compound component represented by the formula (a) and having a molecular weight of 200 or less Component (B): Compound component represented by the formula (b) (C): Number average molecular weight (in terms of polystyrene by GPC) More than 400 polyfunctional cationic curable compounds (excluding compounds contained in component (B))
Component (D): Photocationic polymerization initiator

[Component (A)]
The component (A) of the present invention is a compound (= cationic curable compound) represented by the following formula (a).

The molecular weight of the compound represented by the above formula (a) is 200 or less (for example, 90 to 200), and is preferably 120 to 200, more preferably 140 to 200, and particularly preferably 140 to 200 in that it is more difficult to infiltrate into the silicone mold. Is 160-200, most preferably 180-200.

In the formula (a), the ring Z represents a structure obtained by removing the hydrogen atom of the -NH- group from the structural formula of the heterocyclic aromatic compound containing the -NH- group.

Examples of the heterocyclic aromatic compound containing the -NH- group include compounds represented by the following formulas (z-1) to (z-7). The compound represented by the following formula may have a substituent (for example, C _1-5 alkyl group, etc.).

As the heterocyclic aromatic compound containing a -NH- group, the compounds represented by the above formulas (z-4) to (z-7) are preferable in that they are more difficult to infiltrate into the silicone mold. A compound represented by the above formula (z-7) is particularly preferable.

Therefore, as the component (A), the compound represented by the following formula (a') is particularly preferable in that it is difficult to infiltrate into the silicone mold.

Since the photocurable composition of the present invention contains the low molecular weight component (A), the fine pattern of the mold can be transferred with high accuracy. Further, although the component (A) has a low molecular weight, in the photocurable composition of the present invention, since it is present together with the component (B) described later, infiltration into the silicone mold is suppressed. Furthermore, component (A) has a heterocyclic aromatic hydrocarbon skeleton. Therefore, the etching resistance of the obtained cured product can be increased.

[Component (B)]
The component (B) of the present invention is a compound containing at least one primary hydroxyl group represented by the following formula (b).

In formula (b), R ¹ represents a CH ₂ OH group or a cationically polymerizable group. The cationically polymerizable group includes a vinyl ether group, an epoxy group, and an oxetanyl group.

In the formula (b), L represents a single bond, a divalent hydrocarbon group, or a divalent group formed by bonding two or more hydrocarbon groups via a single bond or a linking group.

The hydrocarbon group includes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

As the aliphatic hydrocarbon group, an aliphatic hydrocarbon group having 1 to 20 carbon atoms (= C _1-20 ) is preferable, and for example, methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene group and the like have 1 carbon number. Alkylene groups of about 10 (preferably 1 to 5, particularly preferably 1 to 3); carbon numbers of vinylene, 1-methylvinylene, propenylene, 1-butenylene, 2-butenylene, 1-pentenylene, 2-pentenylene group and the like. Examples thereof include an alkenylene group of about 2 to 10 (preferably 2 to 5, particularly preferably 2 to 3).

Examples of the alicyclic hydrocarbon group include 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, and 1,4-cyclohexylene. Examples thereof include a cycloalkylene group having 3 to 18 carbon atoms (including a cycloalkylidene group) such as a cyclohexylidene group.

As the aromatic hydrocarbon group, a C _6-14 (particularly C _6-10 ) aromatic hydrocarbon group is preferable, and examples thereof include phenylene, naphthylene, and fluorene groups.

Examples of the linking group include a carbonyl group (-CO-), an ether bond (-O-), a thioether bond (-S-), an ester bond (-COO-) and the like.

Among the compounds represented by the above formula (b), having a cyclic structure is preferable in that an effect of enhancing etching resistance can be obtained, and R ¹ is a cationically polymerizable group having a cyclic structure (for example, an epoxy group). Or, in the case of an oxetanyl group), L is preferably a single bond or an aliphatic hydrocarbon group. On the other hand, when R ¹ is a CH ₂ OH group or a cationically polymerizable group having a cyclic structure (for example, a vinyl ether group), L is a group containing an alicyclic hydrocarbon group or an aromatic hydrocarbon group (or a fat). A group containing a ring or an aromatic ring) is preferable.

In the present invention, the component (B) preferably contains at least a compound (b-1) having a primary hydroxyl group (= CH ₂ OH group) and a cationically polymerizable group in one molecule, and in particular, particularly. A compound (b-1) having a primary hydroxyl group (= CH ₂ OH group) and a cationically polymerizable group in one molecule in that it has the effect of improving curability and enhancing the etching resistance of the obtained cured product. And a compound (b-2) having _two primary hydroxyl groups (= CH ₂ OH groups) in one molecule are preferably contained.

When the component (B) contains the compound (b-1) and the compound (b-2), the content ratio (b-1 / b-2; weight ratio) of these is, for example, 15 / 85-80 / 20. It is particularly preferably 55/45 to 80/20, and most preferably 60/40 to 80/20 in that the effect of increasing the etching resistance of the obtained cured product can be obtained.

The molecular weight of the compound represented by the above formula (b) is, for example, 100 to 500, preferably 150 to 450.

Among the compounds represented by the formula (b), the molecular weight of the compound (b-1) is, for example, 100 to 500, preferably 100 to 450, particularly preferably 100 to 400, and most preferably 100 to 300. .. The molecular weight of compound (b-2) is, for example, more than 300 and 500 or less, preferably 350 to 500, particularly preferably 380 to 500, and most preferably 400 to 480.

Since the component (B) has a primary hydroxyl group, it is difficult to infiltrate into the silicone mold. Further, at the time of curing, the primary hydroxyl group in the component (B) shows a chain transfer reaction. Therefore, the photocurable composition of the present invention containing the component (B) promotes the progress of the cationic polymerization reaction and suppresses the remaining unreacted monomers, so that the cured product has excellent etching resistance. Can be formed.

[Component (C)]
The component (C) of the present invention is a polyfunctional cationic curable compound having a number average molecular weight (in terms of polystyrene by GPC) of 400 or more. The compound contained in the component (B) is not contained in the component (C).

The number average molecular weight of the component (C) is 400 or more, for example, 400 to 10000, preferably 400 to 7000. If the number average molecular weight of the component (C) is less than the above range, it becomes difficult to prevent the infiltration into the silicone mold, and the infiltration of the component (C) into the silicone mold reduces the thickness of the coating film. The shape accuracy of the obtained cured product tends to decrease. In addition, the etching resistance of the obtained cured product tends to decrease. On the other hand, if the number average molecular weight of the component (C) exceeds the above range, it tends to be difficult to transfer the fine pattern of the mold with high accuracy.

The functional group equivalent of the component (C) is, for example, 100 to 400 g / eq, preferably 150 to 300 g / eq.

In the present invention, containing at least a compound (c-1) having a number average molecular weight of 400 to 1000 (particularly 400 to 850) as the component (C) provides shape accuracy and etching resistance of the obtained cured product. A compound (c-1) having a number average molecular weight of 400 to 1000 (particularly 400 to 850) is preferable because it has an effect of increasing the amount of the compound (particularly, 400 to 850), and particularly has an effect of suppressing the ease of infiltration into the silicone mold. ) And the compound (c-2) having a number average molecular weight of 1500 or more (particularly preferably 1500 to 7000, most preferably 1800 to 5000, and particularly preferably 1800 to 4500).

When the component (C) contains the compound (c-1) and the compound (c-2), the content ratio (c-1 / c-2; weight ratio) of these is, for example, 80/20 to 30/70. It is particularly preferably 80/20 to 40/60, and most preferably 80/20 to 50/50 in that the effect of increasing the etching resistance of the obtained cured product can be obtained.

Examples of the cationically polymerizable group include an epoxy group, a vinyl ether group, an oxetanyl group and the like. The component (C) of the present invention may contain one of the cationically polymerizable groups alone or in combination of two or more. In the present invention, a compound containing an epoxy group or an oxetanyl group as a cationically polymerizable group is particularly preferable because it has excellent crosslinkability.

The component (C) of the present invention preferably contains an epoxy compound and / or an oxetane compound, and at least contains an epoxy compound, in that the effect of enhancing the etching resistance of the obtained cured product can be obtained. Is particularly preferable, and it is most preferable to contain an epoxy compound and an oxetane compound.

When the component (C) contains an epoxy compound and an oxetane compound, their content ratios (former / latter; weight ratio) are, for example, 70/30 to 30/70, and have the effect of increasing the etching resistance of the obtained cured product. In terms of the obtained points, it is particularly preferably 70/30 to 50/50, and most preferably 65/35 to 55/45.

As the epoxy compound, a known or commonly used compound having one or more epoxy groups (oxylan rings) in the molecule can be used, and is not particularly limited. Epoxy compounds include, for example, alicyclic epoxy compounds, aromatic epoxy compounds, aliphatic epoxy compounds and the like.

Examples of the alicyclic epoxy compound include known and commonly used compounds having one or more alicyclics and one or more epoxy groups in the molecule, and are not particularly limited, and examples thereof include the following compounds. Be done.
(1) An epoxy group composed of two adjacent carbon atoms and oxygen atoms constituting an alicyclic in the molecule (in the present specification, it may be referred to as an "alicyclic epoxy group". An alicyclic epoxy group. (Contains, for example, a cyclohexene oxide group, etc.) (2) A compound in which an epoxy group is directly bonded to an alicyclic with a single bond (3) A compound having an alicyclic and a glycidyl ether group in the molecule ( Glycidyl ether type epoxy compound)

Examples of the compound having an alicyclic epoxy group in the molecule (1) include compounds represented by the following formulas (c1) and (c2). In addition, n ^{1 to} n ⁶ in the formula represent integers of 1 to 30, respectively.

Examples of the compound in which the epoxy group is directly bonded to the alicyclic (2) by a single bond include a compound represented by the following formula (c3).

In the formula (c3), R'is a group (p-valent organic group) obtained by removing p hydroxyl groups (-OH) from the structural formula of the p-valent alcohol, and p and n ⁷ each represent a natural number. Examples of the p-valent alcohol [R'(OH) _p ] include polyhydric alcohols such as 2,2-bis (hydroxymethyl) -1-butanol (polyhydric alcohols having 1 to 15 carbon atoms, etc.). p is preferably 1 to 6, and n ⁷ is preferably 1 to 30. When p is 2 or more, n ⁷ in each group in [] (inside the outer square brackets) may be the same or different. Specific examples of the compound represented by the above formula (ii) include 1,2-epoxy-4- (2-oxylanyl) cyclohexane adducts of 2,2-bis (hydroxymethyl) -1-butanol [for example. , Product name "EHPE3150" (manufactured by Daicel Corporation), etc.] and the like.

Examples of the compound having an alicyclic ring and a glycidyl ether group in the molecule (3) described above include a hydride bisphenol A type epoxy resin, a hydride bisphenol F type epoxy resin, a hydride biphenol type epoxy resin, and a hydride phenol novolac type epoxy. Examples thereof include resins and hydride cresol novolac type epoxy resins.

Examples of the aromatic epoxy compound include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin and the like.

Examples of the aliphatic epoxy compound include glycidyl ethers of alcohols having no q-valent cyclic structure (q is a natural number); monovalent or polyvalent carboxylic acids [eg, acetic acid, propionic acid, butyric acid, stearic acid, etc. Glycidyl ester of adipic acid, sebacic acid, maleic acid, itaconic acid, etc.; epoxidized products of fats and oils having double bonds such as epoxidized flaxseed oil, epoxidized soybean oil, epoxidized castor oil; Examples thereof include epoxidized compounds (including alkadiene).

As the oxetane compound, for example, an oxetane compound having a cyclic structure (particularly an aromatic ring) such as a compound represented by the following formulas (c4) and (c5) is preferable. In the following formula, n is a number from 1 to 3 and n'is a number from 1 to 3.

[Component (D)]
The component (D) of the present invention is a photocationic polymerization initiator. The photocationic polymerization initiator is a photocationic polymerization initiator that generates cation species by irradiation with light and initiates a curing reaction of a cationically curable compound. The photocationic polymerization initiator consists of a cation part that absorbs light and an anion part that is a source of acid.

Examples of the photocationic polymerization initiator of the present invention include diazonium salt compounds, iodonium salt compounds, sulfonium salt compounds, phosphonium salt compounds, selenium salt compounds, oxonium salt compounds, ammonium salt compounds, and bromine salts. System compounds and the like can be mentioned. These can be used alone or in combination of two or more.

In the present invention, it is particularly preferable to use a sulfonium salt-based compound in that a cured product having excellent curability can be formed. Examples of the cation portion of the sulfonium salt-based compound include [4- (4-biphenylylthio) phenyl] -4-biphenylylphenylsulfonium, (4-hydroxyphenyl) methylbenzylsulfonium ion, triphenylsulfonium ion, and diphenyl [ Examples thereof include aryl sulfonium ions (particularly triaryl sulfonium ions) such as 4- (phenylthio) phenyl] sulfonium ion and tri-p-tolyl sulfonium ion.

The anionic portion of the cationic photopolymerization initiator, for ^{_{example, BF 4 -, [(C}} 6 H 5) s B (C 6 F 5) 4-s] - (s: 0~3 integer), PF ₆ ^- _{, [(Rf) t PF 6} -t] - (Rf: alkyl group in which at least 80% are substituted with fluorine atoms of the hydrogen atom, t: 1 to 5 _{^{integer), AsF 6 -, SbF 6}} -, SbF 5 (OH) ^-, and the like can be given.

Examples of the photocationic polymerization initiator of the present invention include [4- (4-biphenylylthio) phenyl] -4-biphenylylphenylsulfonium tris (pentafluoroethyl) trifluorophosphate and (4-hydroxyphenyl) methylbenzyl. Sulfonium tetrakis (pentafluorophenyl) borate, 4- (4-biphenylylthio) phenyl-4-biphenylylphenyl sulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium tris (pentafluoroethyl) Trifluorophosphate, diphenyl [4- (phenylthio) phenyl] sulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate, trade names "Cyracure UVI-6970", "Cyracure UVI-6974" , "Cyracure UVI-6990", "Cyracure UVI-950" (above, manufactured by Union Carbide, USA), "Irgacure 250", "Irgacure 290", "Irgacure 261", "Irgacure 264" (above, manufactured by BASF). ), "CG-24-61" (manufactured by Ciba Japan), "SP-150", "SP-151", "SP-170", "Optomer SP-171" (all manufactured by ADEKA Co., Ltd.) , "DAICAT II" (manufactured by Daicel Co., Ltd.), "UVAC1590", "UVAC1591" (all manufactured by Daicel Cytec Co., Ltd.), "CI-2064", "CI-2339", "CI-2624", "CI-2481", "CI-2734", "CI-2855", "CI-2823", "CI-2758", "CIT-1682" (all manufactured by Nippon Soda Co., Ltd.), "PI-2074" (Rodia, Tetrax (pentafluorophenyl) borate trilcumyl iodonium salt), "FFC509" (3M), "BBI-102", "BBI-101", "BBI-103", "MPI-" 103 "," TPS-103 "," MDS-103 "," DTS-103 "," NAT-103 "," NDS-103 "(all manufactured by Midori Chemical Co., Ltd.)," CD-1010 "," "CD-1011", "CD-1012" (above, manufactured by Sartomer, USA), "CPI-100P", "CPI-101A" (above, Sun) Commercially available products such as Appro Co., Ltd. can be used.

The content of the component (D) (the total amount when two or more kinds are contained) is 100 parts by weight in total of the component (A), the component (B), and the component (C) contained in the photocurable composition. On the other hand, for example, it is 1 to 10 parts by weight, preferably 2 to 8 parts by weight, and particularly preferably 3 to 7 parts by weight.

[Other ingredients]
The photocurable composition of the present invention may contain other components in addition to the above components, if necessary. Other components include, for example, a solvent, a surface conditioner (= leveling agent), a photosensitizer (for example, a thioxanthone compound), a defoaming agent, a coupling agent (for example, a silane coupling agent), and a surfactant. Examples thereof include conventional additives such as agents, inorganic fillers, flame retardants, ultraviolet absorbers, ion adsorbents, phosphors, mold release agents, pigment dispersants, and dispersion aids. These can be used alone or in combination of two or more.

(Surface conditioner)
It is preferable that the photocurable composition of the present invention contains a surface conditioner because a coating film having excellent surface smoothness can be formed when a coating film is formed by a spin coating method or the like. ..

Surface conditioners include silicone-based surface conditioners (for example, polyether-modified polysiloxane, polyester-modified polysiloxane, aralkyl-modified polysiloxane, etc.), hydrocarbon-based surface conditioners [for example, poly (meth) acrylate, polyether-modified). Poly (meth) acrylate, fluorine-modified poly (meth) acrylate, etc. (all include homopolymers and copolymers)] are included. These can be used alone or in combination of two or more.

The molecular weight of the surface conditioner is, for example, 3000 or more, preferably 4000 to 150,000, more preferably 5000 to 10000, particularly preferably 70000 to 100,000, and most preferably 1000 to 50000. It is preferable to use a surface conditioner having a molecular weight in the above range in that the generation of edge beads can be controlled to be low and the surface smoothness of the obtained coating film can be improved.

As the surface conditioner, for example, commercially available products such as trade names "BYK-UV3510", "BYK-350", "BYK-352], and "BYK-354" (all manufactured by Big Chemie Japan Co., Ltd.) are suitable. Can be used for.

The content of the surface conditioner (the total amount when two or more kinds are contained) is based on 100 parts by weight of the total of the component (A), the component (B), and the component (C) contained in the photocurable composition. For example, it is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight.

(solvent)
The photocurable composition of the present invention may contain a solvent. Examples of the solvent include ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl lactate, ethyl lactate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 3-. Esters such as methoxybutyl acetate and 1-methoxy-2-propyl acetate; ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol Ethers such as monoethyl ether; alcohols such as 3-methoxybutanol and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and cyclohexanone; benzene, toluene, xylene, ethylbenzene, cumene and mesityrene Aromatic hydrocarbons such as, etc. can be mentioned. These can be used alone or in combination of two or more.

As the solvent, a solvent having a boiling point (at 760 mmHg) of, for example, 100 to 210 ° C., preferably 120 to 200 ° C., particularly preferably 130 to 180 ° C., and most preferably 130 to 160 ° C. can be used. , Preferable in terms of coatability.

The content of the solvent (preferably the solvent having the boiling point in the above range) (preferably the total amount when two or more kinds are contained) is such that the concentration of the non-volatile component contained in the photocurable composition is 3 to 90% by weight (preferably). Is preferably in the range of 5 to 80% by weight), and by adding a solvent, the viscosity [at 25 ° C., shear rate of 20 (1 / s)] of the photocurable composition of the present invention can be increased. For example, adjusting to about 0.1 to 500 mPa · s (preferably 1 to 200 mPa · s) is preferable in that the coatability can be improved.

Further, the content of the solvent whose boiling point is outside the above range (the total amount when two or more kinds are contained) can improve the coatability, and the content of the solvent whose boiling point is within the above range (two kinds). When the above is contained, it is preferably 80% by weight or less, more preferably 70% by weight or less, still more preferably 60% by weight or less, still more preferably 50% by weight or less, still more preferably 40% by weight. Below, it is more preferably 30% by weight or less, further preferably 20% by weight or less, particularly preferably 10% by weight or less, most preferably 5% by weight or less, and particularly preferably 1% by weight or less.

[Photocurable composition]
The photocurable composition of the present invention can be prepared, for example, by stirring and mixing the above components at a predetermined ratio and, if necessary, defoaming under vacuum.

The content of the component (A) is, for example, 15 to 60% by weight, preferably 20 to 50% by weight, particularly, with respect to the total content (100% by weight) of the components (A), (B) and (C). It is preferably 25 to 45% by weight. If the content of the component (A) is excessive, the component (A) tends to crystallize and easily precipitate in the coating film.

The content of the component (B) is, for example, 15 to 50% by weight, preferably 20 to 45% by weight, particularly, with respect to the total content (100% by weight) of the components (A), (B) and (C). It is preferably 20 to 40% by weight.

The content of the component (C) is, for example, 10 to 60% by weight, preferably 20 to 50% by weight, particularly, based on the total content (100% by weight) of the components (A), (B) and (C). It is preferably 20 to 35% by weight.

Further, it is preferable to contain an epoxy compound as the component (C) in that the effect of increasing the etching resistance of the obtained cured product and improving the toughness of the pattern portion can be obtained, and the content of the epoxy compound is the component. It is, for example, 5 to 60% by weight, preferably 5 to 50% by weight, and particularly preferably 5 to 30% by weight, based on the total content (100% by weight) of (A), (B), and (C).

Further, it is preferable to contain the oxetane compound as the component (C) in that the effect of increasing the etching resistance of the obtained cured product can be obtained, and the content of the oxetane compound is the components (A), (B), ( With respect to the total content (100% by weight) of C), for example, it is 1 to 30% by weight, preferably 5 to 25% by weight, and particularly preferably 10 to 20% by weight.

In the photocurable composition of the present invention, the weight ratio (A / B) of the content of the component (A) to the component (B) is, for example, 35/65 to 70/30, preferably 40/60 to 60/40. , Particularly preferably 50/50 to 60/40.

The weight ratio (A / C) of the content of the component (A) to the component (C) in the photocurable composition of the present invention is, for example, 45/55 to 25/75, preferably 45/55 to 30/70. Is.

The weight ratio (B / C) of the content of the component (B) to the component (C) in the photocurable composition of the present invention is, for example, 30/70 to 70/30, preferably 35/65 to 60/40. , Particularly preferably 50/50 to 60/40.

The weight ratio [A / (B + C)] of the content of the component (A) to the total content of the component (B) and the component (C) in the photocurable composition of the present invention is, for example, 25/75 to 45. / 55, preferably 35 / 65-45 / 55.

Since the photocurable composition of the present invention has the above-mentioned structure, it is excellent in curability and can quickly form a cured product by light irradiation.

The light (active energy ray) used for the light irradiation may be any light that promotes the polymerization reaction of the photocurable composition, and is infrared rays, visible rays, ultraviolet rays, X rays, electron beams, α rays, and β rays. , Γ-ray, etc. can be used. Of these, ultraviolet rays are preferable because they are easy to handle. For the irradiation of ultraviolet rays, for example, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a carbon arc, a metal halide lamp, sunlight, an LED lamp, a UV-LED, a laser, or the like can be used.

When a thin film having a film thickness of 1 μm is formed by irradiating with ultraviolet rays, the integrated light amount is about 50 to 4000 mJ / cm ² .

Further, since the photocurable composition of the present invention has the above-mentioned structure, infiltration into the silicone mold is suppressed. Therefore, the cured product obtained by subjecting the photocurable composition of the present invention to imprint processing has a highly accurate pattern shape regardless of the number of times the silicone mold has been used.

Further, since the photocurable composition of the present invention has the above-mentioned structure, the obtained cured product has excellent etching resistance, and the etching rate (Er: nm / min) is the etching rate (Es: nm / min) of the silicon substrate. For example, 1.45 or more (preferably 1.5 or more, particularly preferably 1.6 or more). That is, the etching selectivity (Er / Es) is, for example, 1.45 or more (preferably 1.5 or more, particularly preferably 1.6 or more).

[Manufacturing method of optical device]
The method for manufacturing an optical device of the present invention is a step of imprinting a coating film of the photocurable composition to form a cured product having a pattern shape, and etching the substrate using the cured product as a mask. It is characterized in that an optical device is obtained through the above.

More specifically, the formation of a cured product having a pattern shape is performed by applying the above-mentioned photocurable composition to the surface of a substrate to form a coating film, and then imprinting the formed coating film. ..

As the substrate, for example, an inorganic material substrate such as a silicon substrate, a sapphire substrate, a ceramics substrate, an alumina substrate, a gallium phosphide substrate, a gallium arsenide substrate, an indium phosphide substrate, or a gallium phosphide substrate can be used.

Examples of the method of applying the photocurable composition to the surface of the substrate include a spin coating method, a screen printing method, a curtain coating method, a spray method and the like.

The thickness of the coating film is, for example, 0.1 to 20 μm, preferably 0.2 to 4 μm.

In the present invention, since the photocurable composition has a property of being difficult to infiltrate into the silicone mold, when the silicone mold is used as the mold, a coating film having a certain thickness is applied regardless of the number of times the silicone mold is used. By subjecting to printing processing, a cured product having a highly accurate pattern shape can be efficiently produced.

In the imprint process, the mold on which the pattern is formed is brought into contact with the coating film to transfer the pattern to the coating film, and then the coating film to which the pattern is transferred is cured to form a cured product having a pattern shape. How to do it.

The pressing force when the mold is brought into contact with the coating film is, for example, about 100 to 1000 Pa. The time for bringing the mold into contact with the coating film is, for example, about 1 to 100 seconds.

The coating film to which the mold is transferred can be cured by irradiating with light. The light irradiation conditions are the same as in the case of curing the photocurable composition. After the light irradiation, post-cure (for example, heating at 50 to 180 ° C. for about 30 seconds to 3 hours) may be further performed.

After the coating film is cured, a cured product having a highly accurate pattern shape can be obtained by releasing the mold. In the present invention, the cured product thus obtained is used as a mask when etching the substrate.

Examples of the method for etching the substrate include a dry etching method and a wet etching method. In the present invention, it is particularly preferable to use a dry etching method, and in particular, it is preferable to use reactive ion etching (RIE) because it enables highly accurate microfabrication.

After etching the substrate, the cured product used as a mask is removed from the surface of the substrate by a well-known and conventional method.

In the present invention, since the substrate is etched using the cured product having the above-mentioned high-precision pattern shape and excellent etching resistance as a mask, a substrate having a high-precision fine pattern formed on the surface can be manufactured with good yield. can do.

[Optical device]
The optical device of the present invention is a structure including the fine pattern substrate as a constituent unit, and includes, for example, an optical waveguide, a light guide plate, a diffraction grating, a sensor element, a light emitting element, a microlens array, and the like.

When the optical device of the present invention is used, a flat panel display having excellent light extraction efficiency, high brightness, long life, low power consumption, low heat generation, etc. (for example, a mobile device such as a mobile phone or an LCD TV) Etc.) can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The following weight average molecular weights are polystyrene-equivalent values by GPC.

Examples 1 to 4, Comparative Examples 1 to 4
Each component was charged into a flask according to the compounding composition (unit: parts by weight) shown in the table, and a uniform composition was obtained by stirring and mixing at room temperature. The obtained composition was evaluated by the following method.

[Applicability]
The composition was applied onto a silicon wafer using a spin coater and left to stand in an environment of 23 ° C. and 50% RH for 1 hour to obtain a coating film (film thickness: 1 μm). The obtained coating film was visually observed and the coatability was evaluated according to the following criteria.
Evaluation Criteria ○: No repelling, agglomeration / precipitate of coating film ×: Repelling of coating film, agglomeration / deposit

[Curability]
The coating film (thin film: 1 μm) obtained by the same method as the evaluation of [coatability] is irradiated with ultraviolet rays having an integrated light amount of 500 mJ / cm ² using an ultraviolet irradiation device (UV or UV-LED irradiation device). The coating film was cured to form a thin film. The curability of the obtained thin film was evaluated according to the following criteria.
Evaluation criteria ○: No stickiness. No trace of touch is left.
×: There is stickiness. Traces of finger touch remain.

[Change in pattern shape when imprint transfer is repeated]
A silicon mold (pattern height: 2.0 μm, pattern diameter: 1.0 μm, pattern pitch width: 2) was applied to a coating film (thickness: 1 μm) obtained by the same method as in the evaluation of [coatability]. While pressing 0.0 μm), the coating film was cured by irradiating with ultraviolet rays under the same conditions as the evaluation of [curability] to obtain a cured product.
The height of the pattern of the cured product after the silicone mold was released was measured using a three-dimensional optical profiler system (New View3600, Zygo). 5 patterns were measured from 2 arbitrary points, and the measured values at 10 points in total were averaged. Imprint transfer was repeated using the same mold, the pattern height of the first cured product was compared with the pattern height of the tenth cured product, and the magnitude of the change in the pattern shape was evaluated according to the following criteria.
Evaluation Criteria ○: The ratio of (1st pattern height / 10th pattern height) is 0.90 or more to 1.05 or less ×: (1st pattern height / 10th pattern height) ratio Is less than 0.90

[Evaluation of dry etching resistance]
The coating film (film thickness: 1 μm) obtained by the same method as the evaluation of [coatability] was irradiated with ultraviolet rays (1000 mJ / cm ² ) to cure the coating film, thereby obtaining a silicon wafer with a cured product. ..
The obtained silicon wafer with a cured product was heated at 150 ° C. for 10 minutes, and then a part of the cured product was masked with a polyimide tape.
The non-masked surface of the cured product was etched for 10 minutes using an ICP type RIE apparatus.
After etching, the polyimide tape used for the mask is peeled off, and the difference in thickness between the unetched surface (= mask surface) and the etched surface (= non-mask surface) is measured by a profilometer (trade name "T-4000"). The etching rate per minute of the cured product was calculated by measuring using (manufactured by Kosaka Laboratory Co., Ltd.).
Similarly, the silicon wafer was masked with a polyimide tape and etched to obtain the etching rate of the silicon wafer, and the etching selectivity was calculated from the following formula to evaluate the dry etching resistance.
Etching selectivity = Es / Er
(In the formula, Es is the etching rate of the silicon wafer and Er is the etching rate of the cured product of the composition.)

The above results are summarized in the table below.

The compounds used in Examples and Comparative Examples are as follows.
Ingredient (A)
N-VCz: 9-vinylcarbazole, molecular weight: 193, trade name "HRM-C01", manufactured by Nippon Shokubai Fine Techno Chemical Co., Ltd.
Ingredient (B)
CHMVE: 4- (hydroxymethyl) cyclohexylmethyl vinyl ether, molecular weight: 170, trade name "CHMVE", OXT-101: 3-ethyl-3-hydroxymethyloxetane manufactured by Nippon Carbide Industries, Ltd., molecular weight: 116, product Name "Aron Oxetane OXT-101", BPEF manufactured by Toa Synthetic Co., Ltd .: 9,9-bis [4- (2-hydroxyethoxyphenyl)] fluorene, molecular weight: 438, trade name "BPEF", Osaka Gas Chemical Co., Ltd. ) Made
Ingredient (C)
GT401: Epoxy butane tetracarboxylic acid tetrakis- (3-cyclohexenylmethyl) modified epsilon-caprolactone, average molecular weight: 788, functional group equivalent 220 g / eq, trade name "Epolide GT401", OXBP manufactured by Daicel Co., Ltd .: 4, 4'-bis [3-ethyl- (3-oxetanyl) methoxymethyl] biphenyl, average molecular weight: 411, functional group equivalent 205 g / eq, trade name "ETERNACOLL OXBP", NC-3000H manufactured by Ube Kosan Co., Ltd .: biphenol type Epoxy resin, number average molecular weight: 2300, functional group equivalent 290 g / eq, trade name "NC-3000H", Nippon Kayaku Co., Ltd. N-890: modified novolac type epoxy resin, number average molecular weight: 2000, functional group equivalent 210 g / eq, trade name "EPICLON N-890", PB3600 manufactured by DIC Co., Ltd .: epoxidized polybutadiene, number average molecular weight: 5900, functional group equivalent 193 g / eq, trade name "Epolide PB3600", PB4700 manufactured by Daicel Co., Ltd. : Epoxy polybutadiene, number average molecular weight: 5900, functional group equivalent 165 g / eq, trade name "Epolide PB4700", manufactured by Daicel Co., Ltd.
Ingredient (D)
Irg290: Photoacid generator, trade name "Irgacure PAG290", BASF Japan Ltd. CPI-310FG: Photoacid generator, trade name "CPI-310FG", manufactured by Sun Appro Co., Ltd.
Surface conditioner BYK350: Acrylic copolymer, molecular weight: about 20000, trade name "BYK-350", manufactured by Big Chemie Japan Co., Ltd.
Solvent MMPGAC: 1-methoxy-2-propyl acetate, boiling point 145.8 ° C.

Claims (11)

Including the following component (A), component (B), component (C), and component (D)
The content of the component (A) is 20 to 50% by weight of the total content of the component (A), the component (B), and the component (C).
A photocurable composition in which the weight ratio (A / B) of the content of the component (A) to the component (B) is 35/65 to 70/30.
Component (A): A compound represented by the following formula (a) and having a molecular weight of 200 or less.

(In the formula, ring Z indicates a structure obtained by removing the hydrogen atom of the -NH- group from the structural formula of the heterocyclic aromatic compound containing a -NH- group).
Component (B): Compound represented by the following formula (b)

(In the formula, L represents a single bond, a divalent hydrocarbon group, or a divalent group formed by bonding two or more hydrocarbon groups via a linking group, and R ¹ is a CH ₂ OH group or a CH ₂ OH group. Shows cationically polymerizable groups)
Component (C): Polyfunctional cationic curable compound having a number average molecular weight (in terms of polystyrene by GPC) of 400 or more (excluding compounds contained in component (B))
Component (D): Photocationic polymerization initiator The photocurable composition according to claim 1, wherein the component (A) is a compound represented by the following formula (a').

The photocurable composition according to claim 1 or 2, wherein the component (C) is a polyfunctional cationic curable compound having a functional group equivalent of 100 to 400 g / eq. The photocurable composition according to any one of claims 1 to 3, wherein the weight ratio (A / C) of the content of the component (A) to the component (C) is 45/55 to 25/75. Any of claims 1 to 4, wherein the weight ratio [A / (B + C)] of the content of the component (A) to the total content of the component (B) and the component (C) is 25/75 to 45/55. The photocurable composition according to item 1. The invention according to any one of claims 1 to 5, wherein 1 to 10 parts by weight of the component (D) is contained with respect to 100 parts by weight of the total of the component (A), the component (B), and the component (C). Photocurable composition. The invention according to any one of claims 1 to 6, wherein the surface conditioner is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total of the component (A), the component (B), and the component (C). Photocurable composition. The photocurable composition according to any one of claims 1 to 7, further comprising a solvent having a boiling point of 100 ° C. to 210 ° C. (760 mmHg). The photocurable composition according to any one of claims 1 to 8, which is for imprinting. The photocurable composition according to any one of claims 1 to 9, which is used for forming an etching mask. The coating film of the photocurable composition according to any one of claims 1 to 10 is imprinted to form a cured product having a pattern shape, and the cured product is used as a mask to etch a substrate. A method of manufacturing an optical device, which obtains an optical device through the process of etching.