TW201627431A - Photocurable composition for imprinting, pattern formation method, and device production method - Google Patents

Abstract

Provided is a photocurable composition for imprinting, said composition exhibiting good inkjet discharge accuracy that has good temporal stability. Also provided are a pattern formation method and a device production method. This photocurable composition for imprinting contains: a (meth)acrylate (A) that does not include a fluorine atom; a (meth)acrylate (B) that includes a fluorine atom and is represented by general formula (I); and a photopolymerization initiator (C). In the formula, Rf represents a C1-9 fluorine-containing alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a fluorine atom; L represents a single bond, -O-, -OC(=O)-, or -C(=O)O-; R1 represents a hydrogen atom or a methyl group; and n represents an integer from 1 to 8, or represents an integer from 3 to 8 if L is a single bond.

Description

Photocurable composition for imprint, pattern forming method, and device manufacturing method

The present invention relates to a photocurable composition for imprint, a pattern forming method, and a device manufacturing method. More specifically, the present invention relates to a photocurable composition for imprinting, a pattern forming method, and a pattern for forming a pattern by light irradiation: a semiconductor integrated circuit, a microelectromechanical system (Micro-Electro-Mechanical System, MEMS), recording media such as optical discs and magnetic disks, light-receiving devices such as solid-state imaging devices, Light Emitting Diodes (LEDs), Organic Electroluminescence (Organic Electroluminescence), etc. Light-emitting devices, liquid crystal display devices (LCD) and other optical components, diffraction gratings, relief holograms, optical waveguides, optical filters, microlens arrays and other optical components, thin film transistors, organic Components for flat panel displays such as crystals, color filters, anti-reflection films, polarizing devices, optical films, and pillars, nano biocomponents, immunoassay wafers, deoxyribonucleic acid (DNA) separation wafers, microreactors For fine pattern formation (directional self-assembly) by self-assembly of photonic liquid crystals and block copolymers Directed self-assembly (DSA)), such as a guide pattern.

The imprint method is a prototype of a mold that is formed by a known embossing technique in the manufacture of a disc, and which is formed with a concavo-convex pattern (generally referred to as a mold, a stamper, or a template). The technique of fine transfer of fine patterns. When a mold is produced, it is economical to simply form a fine structure such as a nanostructure, and it is economical in recent years, and it is expected to be applied to various fields in recent years.

As a embossing method, a hot stamping method using a thermoplastic resin as a material to be processed (for example, refer to Non-Patent Document 1) and a photoimprint method using a photocurable composition have been proposed (for example, refer to Non-Patent Document 2, Non-Patent Document 2) Patent Document 3). In the hot stamping method, the mold is pressed against a thermoplastic resin heated to a temperature higher than the glass transition temperature, and then cooled to a temperature below the glass transition temperature, and then the mold is peeled off, whereby the fine structure is transferred onto the resin.

On the other hand, in the photoimprint method, the photocurable composition is cured by light irradiation through a light transmissive mold or a light transmissive substrate, and then the mold is peeled off, whereby the fine pattern is transferred onto the photocured material. Since this method can perform imprinting at room temperature, it can be applied to the field of precision processing of ultra-fine patterns such as fabrication of a semiconductor integrated circuit.

Further, since the photoimprint method includes a step of peeling off the mold, the mold release property of the mold is problematic from the beginning. As a method of improving the mold release property of the mold, a method of containing a fluorine-containing compound in the curable composition is known (Patent Documents 1 to 6 and Non-Patent Document 4). [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-114882 [Patent Document 2] International Publication No. WO2006/114958 (Patent Document 3) Japanese Patent Laid-Open Publication No. 2008-95037 [Patent Document 4] Japanese Patent Laid-Open Publication No. 2010 [Patent Document 5] Japanese Patent Laid-Open Publication No. 2010-239121 [Patent Document 6] Japanese Patent Laid-Open Publication No. 2010-45163 [Non-Patent Document]

[Non-Patent Document 1] S. Chou et al., "Appl. Phys. Lett.", 67, 3114 (1995) [Non-Patent Document 2] J. Haysma (J .Haisma) et al., "J. Vac. Sci. Technol. B", 14(6), 4124 (1996) [Non-Patent Document 3] M. Colbun ) et al., Proc. SPIE, 3676, 379 (1999) [Non-Patent Document 4] MW Lin et al., "Micro/Nano lithography, MEMS" , J. Micro/Nanolith. MEMS MOEMS, 7(3), 033005 (2008)

[Problems to be solved by the invention]

As one of the methods of applying the photocurable composition for imprinting onto a substrate or a mold, there is an inkjet method. In the inkjet method, since the coating amount of the photocurable composition can be adjusted according to the coarseness of the pattern, the thickness unevenness of the residual film can be reduced, and the pattern transfer property of the etching process is excellent. Further, compared with the spin coating method, the material utilization efficiency is high, and the production cost is reduced or the environmental load is reduced. On the other hand, in order to form a fine pattern with good precision, it is required to control the deposition position of the liquid droplets ejected from the inkjet head with high precision.

In the inkjet method, the photocurable composition may be placed in a state of being stored in a tank such as an ink-jet cartridge for a long period of time. According to the study by the inventors of the present invention, it has been found that the photocurable composition stored in the ink jet cartridge for a long period of time may have a lowered ink jet ejection accuracy.

Therefore, an object of the present invention is to provide a photocurable composition for imprinting, a pattern forming method, and a device manufacturing method which are excellent in ink jet ejection accuracy and excellent in temporal stability of ink jet ejection accuracy. [Means for solving the problem]

The inventors of the present invention conducted intensive studies based on the above-described conditions, and as a result, have found that the object can be attained by using a fluorine atom-containing (meth) acrylate described later, and completed the present invention. The present invention provides the following. <1> A photocurable composition for imprinting, comprising: a (meth) acrylate (A) having no fluorine atom, a (meth) acrylate (B) containing a fluorine atom, and a photopolymerization initiator (C), and the fluorine atom-containing (meth) acrylate (B) is represented by the following general formula (I), [Chemical Formula 1] In the formula, R ^f represents a fluorine-containing alkyl group having 1 to 9 carbon atoms in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, and L represents a single bond, -O-, -OC(=O)- or -C(= O)O-, R ¹ represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 8. When L is a single bond, it represents an integer of 3 to 8. <2> The photocurable composition for imprint according to <1>, wherein the fluorine atom-containing (meth) acrylate (B) has a boiling point of from 100 ° C to 200 ° C at a pressure of 0.67 kPa. <3> The photocurable composition for imprint according to <1> or <2>, wherein in the general formula (I), a hydrogen atom wherein ^Rf is 40% to 100% of an alkyl group is substituted with a fluorine atom. A fluorine-containing alkyl group having 1 to 9 carbon atoms. The photocurable composition for imprint according to any one of <1>, wherein, in the formula (I), R ^f is a perfluoroalkyl group having 4 to 6 carbon atoms; (Perfluoroalkyl) with a C 1 to 3 alkyl group. The photocurable composition for imprint according to any one of <1> to <4> which contains 1% by mass to 5% by mass of a fluorine atom in the photocurable composition for imprinting. (Meth) acrylate (B). <6> The photocurable composition for imprint according to any one of <1> to <5> further comprising 1% by mass to 5% by mass of a non-polymerizable compound having a polyoxyalkylene group structure ( D). <7> The photocurable composition for imprint according to any one of <1> to <6> which has a viscosity of 5 mP·s to 12 mP·s at 23 ° C and a surface tension of 27 mN. /m～33 mN/m. <8> A pattern forming method comprising the step of applying the photocurable composition for imprint according to any one of <1> to <7> to a substrate or having a pattern by the inkjet method. In the mold, the photocurable composition for imprinting is held by the mold and the substrate; and the photocurable composition for imprinting is held by the mold and the substrate, and light hardening is performed for imprinting. The composition hardens; and the mold is peeled off. <9> A device manufacturing method comprising the step of etching a substrate by using a pattern formed by the pattern forming method according to <8> as a mask. [Effects of the Invention]

According to the present invention, it is possible to provide a photocurable composition for imprinting, a pattern forming method, and a device manufacturing method which are excellent in inkjet ejection accuracy and excellent in temporal stability of inkjet ejection accuracy.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be carried out in accordance with a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

In the present specification, the term “～” is used in the sense that the numerical values described before and after are included as the lower limit and the upper limit. In the present specification, "(meth)acrylate" means acrylate and methacrylate, "(meth)acrylic" means acrylic acid and methacrylic acid, and "(meth)acryloyl group" means propylene fluorenyl group and Acryl fluorenyl. In the present specification, "imprint" preferably means a pattern transfer of a size of from 1 nm to 100 μm, and more preferably a pattern transfer of a size of 10 nm to 1 μm (nano embossing). In the expression of the group (atomic group) in the present specification, the unsubstituted and unsubstituted expressions are not described as including a group having no substituent, and also a group having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, "light" includes not only light or electromagnetic waves of wavelengths in the ultraviolet, near-ultraviolet, far-ultraviolet, visible, infrared, etc., but also radiation. The radiation includes, for example, microwaves, electron beams, Extreme Ultraviolet Lithography (EUV), and X-rays. In addition, 248 nm excimer laser, 193 nm excimer laser, 172 nm excimer laser and other laser light can also be used. The light may be monochromatic light (single-wavelength light) passing through the optical filter, or different light (composite light) of a plurality of wavelengths. In the present specification, the term "solid content" means the total mass of the components obtained by removing the solvent from the total composition of the composition.

<Photocurable Composition for Imprinting> The photocurable composition for imprint of the present invention (hereinafter sometimes referred to simply as "the curable composition of the present invention") contains a (meth) acrylate having no fluorine atom. (A), a fluorine atom-containing (meth) acrylate (B) and a photopolymerization initiator (C), and a fluorine atom-containing (meth) acrylate (B) is represented by the following formula (I) (meth) acrylate. Hereinafter, the "fluorine atom-free (meth) acrylate (A)" is also referred to as "(meth) acrylate (A)". Further, the "fluorine atom-containing (meth) acrylate (B)" is also referred to as "fluorine (meth) acrylate (B)".

The curable composition of the present invention has excellent ink jet ejection accuracy, and the ink jet ejection accuracy is excellent in stability over time. The reason for speculating this effect is as follows. Since the curable composition of the present invention contains the fluorine-containing (meth) acrylate (B), the surface tension of the composition can be appropriately lowered, and the ink jet ejection accuracy is excellent. Further, the surface energy of the cured film can be lowered, and the mold release property is excellent. As described above, in the inkjet method, the curable composition is ejected from the nozzle head of the inkjet coating device, and the curable composition is applied onto the substrate or the mold, but depending on the use conditions, there are The curable composition is placed in a state of being stored in a storage tank for a long period of time. The curable composition of the present invention contains the fluorine-containing (meth) acrylate (B) represented by the following formula (I). The fluorine-containing (meth) acrylate (B) represented by the formula (I) is less volatile because of its relatively high boiling point. Therefore, it is considered that the change in surface tension during storage of the curable composition of the present invention is small, and the stability with time of inkjet ejection accuracy can be improved. Hereinafter, each component of the curable composition of the present invention will be described.

<<(Meth)acrylate (A)>> The curable composition of the present invention contains (meth) acrylate (A). The (meth) acrylate (A) is a (meth) acrylate having no fluorine atom, and is not particularly limited as long as it does not deviate from the gist of the present invention. The curable composition of the present invention preferably uses a monofunctional (meth) acrylate (A1) having one (meth) acryloxy group and a polyfunctional group having two or more (meth) acryloxy groups. (Meth) acrylate (A2) is used as (meth) acrylate (A).

<<Monofunctional (meth) acrylate (A1)>> The monofunctional (meth) acrylate (A1) may, for example, be a chain aliphatic (meth) acrylate (A1-1), or have an aromatic structure or a fat. a (meth) acrylate (A1-2) having a cyclic hydrocarbon structure, a chain aliphatic (meth) acrylate (A1-1), and a (meth) acrylate (A1-2) other than (meth) acrylate The acrylate (A1-3) (hereinafter also referred to as (meth) acrylate (A1-3) having another structure) is preferably a chain aliphatic (meth) acrylate (A1-1).

In the present invention, the molecular weight of the monofunctional (meth) acrylate (A1) is preferably from 160 to 350, more preferably from 195 to 315, still more preferably from 210 to 285, most preferably from 225 to 270. If the molecular weight is in the above range, it can have both low viscosity and low volatility.

In the present invention, the monofunctional (meth) acrylate (A1) preferably has a boiling point of from 80 ° C to 220 ° C, more preferably from 100 ° C to 200 ° C, and even more preferably from 110 ° C to 180 ° C at a pressure of 0.67 kPa. The optimum is from 120 ° C to 160 ° C. When the boiling point is 100 ° C or more at a pressure of 0.67 kPa, volatilization of the monofunctional (meth) acrylate (A1) during storage can be suppressed. When the boiling point is 200 ° C or less at a pressure of 0.67 kPa, distillation purification can be easily performed, and a highly functional monofunctional (meth) acrylate (A1) can be produced with good productivity.

The chain aliphatic (meth) acrylate (A1-1) is preferably an ester of a linear or branched aliphatic alcohol having a carbon number of 8 to 20 and (meth)acrylic acid, more preferably a carbon number of 9 to 16. An ester of a linear or branched aliphatic alcohol and (meth)acrylic acid, and more preferably an ester of a linear or branched aliphatic alcohol having a carbon number of 10 to 14 and (meth)acrylic acid, preferably having a carbon number of 12 An ester of a linear or branched aliphatic alcohol with (meth)acrylic acid. In the present invention, the "chain aliphatic (meth) acrylate" means a linear or branched aliphatic (meth) acrylate which does not contain an aromatic structure, an alicyclic hydrocarbon structure or a heterocyclic structure. ester. Specific examples of the chain aliphatic (meth) acrylate (A1-1) include n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and fluorene (meth) acrylate. Ester, isodecyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, 2-propylheptyl (meth)acrylate, (11) Alkyl ester, n-dodecyl (meth)acrylate, 2-butyloctyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate A base ester, n-hexadecyl (meth)acrylate, or 2-octadecyl (meth)acrylate. More preferably, these compounds are n-decyl acrylate, isodecyl acrylate, 2-propylheptyl acrylate, n-undecyl acrylate, n-dodecyl acrylate, 2-butyl octyl acrylate. Ester, n-tridecyl acrylate, n-tetradecyl acrylate, and further preferably n-undecyl acrylate, n-dodecyl acrylate, 2-butyloctyl acrylate, acrylic Alkyl esters, n-tetradecyl acrylate, especially n-dodecyl acrylate or 2-butyloctyl acrylate.

The (meth) acrylate (A1-2) having an aromatic structure or an alicyclic hydrocarbon structure is more preferably an aromatic alcohol having 7 to 20 carbon atoms or an ester of an alicyclic alcohol and (meth)acrylic acid, and further preferably The aromatic alcohol having 8 to 15 carbon atoms or the ester of alicyclic alcohol and (meth)acrylic acid is preferably an aromatic alcohol having 9 to 13 carbon atoms or an ester of an alicyclic alcohol and (meth)acrylic acid. Specific examples of the (meth) acrylate (A1-1) having an aromatic structure or an alicyclic hydrocarbon structure can be exemplified by benzyl (meth) acrylate and 2-phenoxyethyl (meth) acrylate. Benzyl (meth)acrylate having a substituent on the aromatic ring (preferably, the substituent is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group), or (meth)acrylic acid 1-naphthyl ester or 2-naphthyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate or 2-naphthylmethyl (meth)acrylate, (meth)acrylic acid-1 -naphthylethyl ester or 2-naphthylethyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, 1-ethylcyclopentyl (meth)acrylate, ( 1-ethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, (meth)acrylic acid Adamantyl ester. Among these compounds, benzyl acrylate or 2-naphthylmethyl acrylate having a linear or branched alkyl group having 3 to 6 carbon atoms is particularly preferred on the aromatic ring.

The (meth) acrylate (A1-3) having another structure may, for example, be a (meth) acrylate having a polar functional group or a heterocyclic structure. Specific examples of the (meth) acrylate (A1-3) having another structure include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and (meth)acrylic acid. -4-hydroxybutyl ester, polyethylene glycol (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, 2-methoxyethyl (meth) acrylate, Methoxy triethylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, methoxy dipropylene glycol (meth) acrylate, methoxy tripropylene glycol (meth) acrylate Ester, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth) acrylate, 2-cyanoethyl acrylate, N-N-dimethylamine (meth)acrylate Ethyl ethyl ester, tert-butylaminoethyl (meth)acrylate, tetramethylpiperidine (meth)acrylate, pentamethylpiperidine (meth)acrylate, (meth)acrylic acid-β- Carboxyethyl ester, 2-(meth)acryloxyethyl succinic acid, (meth) propylene oxirane ethyl phosphate, glycidyl (meth) acrylate, (meth) acrylate (3 -ethyl-3-oxetanyl)methyl ester, (meth) propylene Tetrahydrofurfuryl ester, 2,2-dimethyl-4-(methyl)propenyloxymethyldioxolane, 2-ethyl-2-methyl-4-(methyl)propene醯oxymethyldioxolane, 2-isobutyl-2-methyl-4-(methyl)propenyloxymethyldioxolane, γ-butyrolactone (methyl Acrylate, mevalonol (meth) acrylate. When the (meth) acrylate having a polar functional group or a heterocyclic structure is added, the adhesion between the cured product and the substrate may be improved.

The monofunctional (meth) acrylate (A1) is preferably contained in an amount of 5 to 60% by mass in the curable composition of the present invention. The lower limit is more preferably 10% by mass or more. The upper limit is more preferably 40% by mass or less, and further preferably 30% by mass or less. When the content of the monofunctional (meth) acrylate (A1) is 10% by mass or more, the ink jet ejection accuracy and the mold release property can be improved. In addition, when the content of the monofunctional (meth) acrylate (A1) is 40% by mass or less, a pattern excellent in film strength can be obtained. The monofunctional (meth) acrylate (A1) may be used alone or in combination of two or more. When two or more cases are used, it is preferable that the total amount thereof becomes the above range.

<<Polyfunctional (meth)acrylate (A2)>> The polyfunctional (meth)acrylate (A2) is preferably an aliphatic polyol or an ester of an aromatic polyol and (meth)acrylic acid. The polyfunctional (meth) acrylate (A2) is a (meth) acrylate having two or more (meth) acryloxy groups, and is not particularly limited as long as it does not deviate from the gist of the present invention, and is more preferably It has two to six (meth) propylene fluorenyloxy groups, and further preferably has two or three (meth) propylene decyloxy groups, and preferably has two (meth) propylene fluorenyloxy groups. The polyfunctional (meth) acrylate (A2) is preferably a polyfunctional (methyl) acrylate (A2-1) and/or a chain aliphatic group having an aromatic structure or an alicyclic hydrocarbon structure. ) Acrylate (A2-2). When the (meth) acrylate (A2-1) having an aromatic structure or an alicyclic hydrocarbon structure is contained, the etching resistance tends to be improved, and it is preferable. When the chain-like aliphatic polyfunctional (meth) acrylate (A2-2) is contained, the viscosity can be lowered, so that it is preferable to improve the inkjet discharge property or the filling property of the concave-convex pattern of the mold. The polyfunctional (meth) acrylate (A2) may be composed only of a (meth) acrylate (A2-1) having an aromatic structure or an alicyclic hydrocarbon structure, or may be a polyfunctional group only of a chain aliphatic group ( Methyl acrylate (A2-2) may also comprise (meth) acrylate (A2-1) having an aromatic structure or an alicyclic hydrocarbon structure and a polyfunctional (meth) acrylate having a chain aliphatic group Ester (A2-2).

The molecular weight of the polyfunctional (meth) acrylate (A2) is preferably from 170 to 600, more preferably from 190 to 300, still more preferably from 210 to 270. If the molecular weight is in the above range, low volatility, low viscosity, and film strength can be achieved at the same time. The polyfunctional (meth) acrylate (A2) preferably has a boiling point of 90 ° C or more, more preferably 100 ° C or more, and further preferably 110 ° C or more at a pressure of 0.67 kPa.

Specific examples of the polyfunctional (meth) acrylate (A2-1) include phthalic acid (meth) acrylate, isophthalic acid (meth) acrylate, p-benzene di(meth) acrylate, and o. Xylene di(meth) acrylate, m-xylene di(meth) acrylate, p-xylene di(meth) acrylate, bisphenol A di(meth) acrylate, ethylene oxide (Ethylene Oxide) , EO) modified bisphenol A di(meth) acrylate, propylene oxide (Propylene Oxide, PO) modified bisphenol A di(meth) acrylate, EO modified bisphenol F di(meth) acrylate Ester, 9,9-bis[4-(2-(methyl)acryloxyethoxyethoxy)phenyl]anthracene, cyclohexanediol di(meth)acrylate, cyclohexanedimethanol di(a) Acrylate, norbornane dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 1,3-adamantanediol di(meth)acrylate. Among these compounds, m-xylene diacrylate, cyclohexane dimethanol diacrylate, and tricyclodecane dimethanol diacrylate can be preferably used in the present invention. Specific examples of the polyfunctional (meth) acrylate (A2-2) include ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, and 1,4-butylene. Diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 3-methyl-1,5-pentanediol (Meth) acrylate, 1,9-nonanediol di(meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth) acrylate, 1,10-fluorene Diol (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol Di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(methyl) Acrylate, EO modified neopentyl glycol di(meth)acrylate, PO modified neopentyl glycol di(meth)acrylate, 2,2-dimethyl-3-((meth)propene oxime Oxy)propionic acid 2,2-dimethyl-3-((meth)propenyloxy)propyl ester, 2-hydroxy-3-propenyloxypropyl methacrylate, trishydroxyl Propane tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate Ester, tris(2-(methyl)propenyloxyethyl) isocyanurate. Among these compounds, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 3- Methyl-1,5-pentanediol diacrylate and 2-butyl-2-ethyl-1,3-propanediol diacrylate are particularly preferably used in the present invention.

The polyfunctional (meth) acrylate (A2) is preferably contained in the curable composition of the present invention in an amount of 40% by mass to 89% by mass. The lower limit is more preferably 50% by mass or more. The upper limit is more preferably 75% by mass or less. When the content of the polyfunctional (meth) acrylate (A2) is in the above range, a pattern excellent in film strength can be obtained. The mass of the monofunctional (meth) acrylate (A1) and the polyfunctional (meth) acrylate (A2) is preferably from 10:90 to 40:60, more preferably from 15:85 to 35:55, and further preferably 20:80~30:70. By setting it as such a range, it is possible to improve the jet ejection precision, the mold filling property, the hardenability, the mold release property, the strength of the cured film, and the etching resistance. The polyfunctional (meth) acrylate (A2) may be used alone or in combination of two or more. When two or more cases are used, it is preferable that the total amount thereof becomes the above range.

<<Fluorinated (meth) acrylate (B)>> The curable composition of the present invention contains the fluorine-containing (meth) acrylate (B) represented by the following formula (I). [Chemical 2] In the formula, R ^f represents a fluorine-containing alkyl group having 1 to 9 carbon atoms in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, and L represents a single bond, -O-, -OC(=O)- or -C(= O)O-, R ¹ represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 8. When L is a single bond, it represents an integer of 3 to 8.

In the formula (I), R ^f represents a fluorine-containing alkyl group having 1 to 9 carbon atoms in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom. R ^f may be any of a linear chain, a branched shape, and a cyclic shape, and is preferably a linear chain or a branched shape, and more preferably a linear chain. In the present specification, the "fluorinated alkyl group having 1 to 9 carbon atoms in which at least one hydrogen atom of the alkyl group is substituted by a fluorine atom" means an alkyl group having 1 to 9 carbon atoms containing a fluorine atom as a substituent. It is not limited to a group in which a hydrogen atom of an alkyl group is substituted by a fluorine atom. The carbon number of R ^f is more preferably from 2 to 9, further preferably from 4 to 9, more preferably from 5 to 8, particularly preferably from 6 to 8. The substitution ratio of the fluorine atom of R ^f is preferably from 40% to 100%, more preferably from 50% to 90%, still more preferably from 65% to 85%. According to this aspect, the mold release property can be improved. The substitution ratio of the fluorine atom means a ratio (%) in which a hydrogen atom of the alkyl group having 1 to 9 carbon atoms is substituted with a fluorine atom. R ^{f is} preferably a fluorine-containing alkyl group having a C 4-6 perfluoroalkyl group and a C 1-3 alkylene group, or a C 4-6 ω-H-perfluoroalkyl group and carbon The fluoroalkyl group having 1 to 3 alkylene groups is more preferably a fluorine-containing alkyl group having a C 4-6 perfluoroalkyl group and a C 1-3 alkylene group. Specific examples of R ^f include CF ₃ CH ₂ -, CF ₃ CF ₂ CH ₂ -, CF ₃ (CF ₂ ) ₂ CH ₂ -, CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ -, CF ₃ (CF ₂ ) ₄ CH ₂ CH ₂ CH ₂ -, CF ₃ (CF ₂ ) ₄ CH ₂ -, CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ -, CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ CH ₂ -, (CF ₃ ) ₂ CH-, (CF ₃ ) ₂ C(CH ₃ )CH ₂ -, (CF ₃ ) ₂ CF(CF ₂ ) ₂ CH ₂ CH ₂ -, (CF ₃ ) ₂ CF(CF ₂ ) ₄ CH ₂ CH ₂ -, H(CF ₂ ) ₂ CH ₂ -, H(CF ₂ ) ₄ CH ₂ -, H(CF ₂ ) ₆ CH ₂ -, H(CF ₂ ) ₈ CH ₂ -, and the like. More preferably, these groups are CF ₃ (CF ₂ ) ₄ CH ₂ -, CF ₃ (CF ₂ ) ₅ CH ₂ -, CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ -, CF ₃ (CF ₂ ). ₅ CH ₂ CH ₂ CH ₂ -, H(CF ₂ ) ₆ CH ₂ -, and further preferably CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ - or CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ CH ₂ -, More preferably, it is CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ -.

In the formula (I), L represents a single bond, -O-, -OC(=O)- or -C(=O)O-, more preferably -O- or -OC(=O)-, most preferably Is -O-.

In the formula (I), R ¹ represents a hydrogen atom or a methyl group. From the viewpoint of reactivity, R ^{1 is} preferably a hydrogen atom. In the formula (I), n represents an integer of 1 to 8, and when L is a single bond, it represents an integer of 3 to 8. In the case where L is -O-, -OC(=O)- or -C(=O)O-, n is more preferably from 1 to 5, still more preferably from 1 to 3. In the case where L is a single bond, n is more preferably from 3 to 7, and further preferably from 3 to 5. By setting n to the above range, the boiling point at a pressure of 0.67 kPa can be adjusted to 100 ° C to 200 ° C.

The molecular weight of the fluorine-containing (meth) acrylate (B) is preferably 430 to 600, more preferably 440 to 550, still more preferably 450 to 500. When the molecular weight is in the above range, the volatility can be suppressed while achieving the purification efficiency of distillation.

In the present invention, the fluorine-containing (meth) acrylate (B) preferably has a boiling point of from 100 ° C to 200 ° C, more preferably from 100 ° C to 180 ° C, even more preferably from 100 ° C to 160 ° C at a pressure of 0.67 kPa. When the boiling point is 100 ° C or more at a pressure of 0.67 kPa, volatilization of the fluorine-containing (meth) acrylate (B) during storage can be suppressed. When the boiling point is 200 ° C or less at a pressure of 0.67 kPa, distillation purification can be easily performed, and a highly purified fluorine-containing (meth) acrylate (B) can be produced with good productivity.

Preferable specific examples of the fluorine-containing (meth) acrylate (B) include the following compounds, but are not limited thereto. [Chemical 3]

The fluorine-containing (meth) acrylate (B) is preferably contained in the curable composition of the present invention in an amount of 1% by mass to 5% by mass, more preferably 1% by mass to 3% by mass. When the content of the fluorine-containing (meth) acrylate (B) is 1% by mass or more, the mold release property is further improved. In addition, when the content of the fluorine-containing (meth) acrylate (B) is 5% by mass or less, the pattern roughness is excellent. The fluorine-containing (meth) acrylate (B) may be used alone or in combination of two or more. When two or more cases are used, it is preferable that the total amount thereof becomes the above range. In addition, the content of the fluorine-containing (meth) acrylate (B) is preferably 1% by mass based on the total content of the monofunctional (meth) acrylate (A1) and the polyfunctional (meth) acrylate (A2). ～10% by mass, more preferably 1% by mass to 7% by mass, still more preferably 1% by mass to 4% by mass. By setting this range, the surface tension of the composition can be adjusted to an appropriate value.

<<Other polymerizable compound>> The curable composition of the present invention may contain a polymerizable compound other than the (meth) acrylate (A) and the fluorine (meth) acrylate (B) described above ( Also known as other polymeric compounds). For example, an epoxy compound, an oxetane compound, a vinyl ether compound, a styrene derivative, a propylene ether, a butylene ether, etc. are mentioned. Specific examples thereof include the compounds described in Paragraph No. 0020 to Paragraph No. 0098 of JP-A-2011-231308, the contents of which are incorporated herein by reference. Further, the curable composition of the present invention may be set to have a composition substantially free of other polymerizable compounds. The phrase "substantially free of other polymerizable compounds" means that other polymerizable compounds are not intentionally added.

<Photopolymerization initiator (C)> The curable composition of the present invention contains a photopolymerization initiator. The photopolymerization initiator can be used as long as it is a compound which generates an active species which polymerizes a polymerizable compound by light irradiation. The photopolymerization initiator is preferably a radical polymerization initiator, a cationic polymerization initiator, and more preferably a radical polymerization initiator.

As the radical photopolymerization initiator, for example, a commercially available initiator can be used. As an example of such a starter, for example, the compound described in Paragraph No. 0091 of JP-A-2008-105414 can be preferably used. Among them, an acetophenone-based compound, a mercaptophosphine oxide-based compound, and an oxime ester-based compound are preferred from the viewpoint of curing sensitivity and absorption characteristics. Commercially available products include: Irgacure (registered trademark) 1173, Irgacure 184, Irgacure 2959, Irgacure 127, Irgacure 907, Irgacure 369, Irgacure 379, Lucirin (registered trademark) TPO, Irgacure 819, Irgacure OXE-01, Irgacure OXE-02, Irgacure 651, Irgacure 754, etc. (above is BASF).

The photopolymerization initiator may be used singly or in combination of two or more. When two or more kinds are used in combination, it is more preferred to use two or more kinds of radical polymerization initiators in combination. Specifically, Irgacure 1173 and Irgacure 907, Irgacure 1173 and Lucirin TPO, Irgacure 1173 and Irgacure 819 are exemplified: Irgacure 1173 and Irgacure 907, Irgacure 1173 and Lucirin TPO, Irgacure 1173 and Irgacure 819 , Irgacure 1173 and Irgacure OXE01, Irgacure 907 and Lucirin TPO, Irgacure 907 and Irgacure 819. By setting this combination, the exposure margin can be further expanded. A preferred ratio (mass ratio) in the case of using a photopolymerization initiator is preferably from 9:1 to 1:9, preferably from 8:2 to 2:8, and more preferably from 7:3 to 3:7.

The content of the photopolymerization initiator is preferably from 0.1% by mass to 15% by mass, more preferably from 0.5% by mass to 10% by mass, even more preferably from 1% by mass to 5% by mass, based on the curable composition. The curable composition may contain only one photopolymerization initiator, and may contain two or more photopolymerization initiators. In the case of containing two or more kinds of photopolymerization initiators, it is preferred that the total amount thereof is in the above range. When the content of the photopolymerization initiator is 0.1% by mass or more, sensitivity (rapid hardenability), resolution, line edge roughness, and film strength tend to be further improved. In addition, when the content of the photopolymerization initiator is 15% by mass or less, light permeability, coloring property, workability, and the like tend to be improved, which is preferable.

<<Non-polymerizable compound (D) having a polyoxyalkylene group structure>> The curable composition of the present invention preferably contains a non-polymerizable compound having a polyoxyalkylene group structure in order to improve the mold release property. (D). Here, the non-polymerizable compound means a compound which does not have a polymerizable group. The polyoxyalkylene structure is more preferably a polyoxyalkylene structure, a polyoxyalkylene structure, a polyoxybutylene structure or a mixed structure of the structures, and further preferably a polyoxyethylene structure or a polyoxygen extension. The propyl structure is particularly preferably a polyoxypropylene propyl structure. Further, it is also preferred to have a structure in which a polyol such as glycerin or pentaerythritol is branched as a core. The polyoxyalkylene structure preferably has three to thirty polyoxyalkylene structural units, more preferably five to twenty polyoxyalkylene structural units, and preferably has seven to ten The five polyoxyalkylene structural units, particularly preferably having nine to thine polyoxyalkylene structural units. The hydroxyl group at the terminal of the polyoxyalkylene structure may be unsubstituted, or at least one may be substituted with an organic group or may be entirely substituted with an organic group. The organic group is preferably an organic group having 1 to 20 carbon atoms, and may contain an oxygen atom, a fluorine atom or a ruthenium atom, and preferably has no fluorine atom or ruthenium atom. The organic group is preferably bonded to the polyoxyalkylene structure via an ether bond, an ester bond or a divalent linking group. Specific examples of the organic group are a hydrocarbon group such as a methyl group, an ethyl group, a butyl group, an octyl group, a benzyl group or a phenyl group, a fluorine-containing alkyl group, a fluorine-containing alkyl ether group or a polyoxyalkylene group. The number average molecular weight of the non-polymerizable compound (D) is preferably from 300 to 3,000, more preferably from 400 to 2,000, still more preferably from 500 to 1,500. Specific examples of the non-polymerizable compound (D) include polyoxyethylene (also known as polyethylene glycol), polyoxypropylidene (also known as polypropylene glycol), polyoxybutylene, polyoxyalkylene Ethyl-polyoxyl extended propyl (block and random), polyoxylated ethyl (hereinafter abbreviated as PEG) glyceryl ether, polyoxypropyl propyl (hereinafter referred to as PPG) glyceryl ether, PEG-PPG glyceryl ether, PEG bisphenol A ether, PEG trimethylolpropane ether, PEG pentaerythritol ether, PEG neopentyl glycol ether, PEG trimethylolpropane ether, PEG methyl ether, PEG butyl ether, PEG 2-ethylhexyl ether, PEG laurel Ether, PEG oleyl ether, PPG methyl ether, PPG butyl ether, PPG lauryl ether, PPG oleyl ether, PEG phenyl ether, PEG octyl phenyl ether, PEG phenyl phenyl ether, PEG naphthyl ether, PEG styrene Phenyl ether, PPG phenyl ether, PPG octyl phenyl ether, PPG decyl phenyl ether, PEG dimethyl ether, PEG dibenzyl ether, PPG dimethyl ether, PPG dibenzyl ether, PEG-PPG dimethyl ether, PEG glyceryl ether Ether, PPG glyceryl ether trimethyl ether, PEG monoacetate, PEG monolaurate, PEG monooleate, PPG monoacetate, PPG monolaurate, PPG monooleate, PEG diacetate, PEG dilaurate, PEG II Oleate, PPG diacetate, PPG dilaurate, PPG dioleate, PEG glycerol fatty acid ester, PEG sorbitan fatty acid ester, PEG sorbitan fatty acid ester, 2, 4, 7, 9 - an ethylene oxide adduct such as tetramethyl-5-nonene-4,7-diol (for example, Olefin E1004 manufactured by Nissin Chemical Industry Co., Ltd., Olefin E1010, Olefin E1020, etc., Surfinol 420, Surfinol 440, Surfinol 465, Surfinol manufactured by Air Products & Chemicals 485, Surfino (250), Sofinol (2505, etc.), a fluorine-containing compound represented by the following formula (II).

General formula (II) [Chemical 4] In the formula (II), Rf ² and Rf ³ each independently represent a fluorine-containing alkyl group having 1 to 6 carbon atoms and having two or more fluorine atoms; and p1 and p2 each independently represent an integer of 1 to 3, q1 and Q2 independently represents an integer of 0 to 2, r represents an integer of 2 to 4, and s represents 6 to 20. The preferred range of Rf ² and Rf ³ in the formula (II) is the same as the preferred range of R ^f in the formula (I), and the preferred ranges or specific examples of Rf ² and Rf ³ are also the same. In the formula (II), p1 and p2 each independently represent an integer of 1 to 3, preferably 1 or 2, more preferably 1. Q1 and q2 each independently represent an integer of 0 to 2, preferably 1 or 2, and more preferably 1. r represents an integer of 2 to 4, preferably 2 or 3, more preferably 2. s represents 6 to 20, preferably 7 to 15, more preferably 9 to 13.

The non-polymerizable compound (D) can be referred to the description of paragraphs 0105 to 0106 of JP-A-2013-036027, the contents of which are incorporated herein by reference. The content of the non-polymerizable compound (D) in the total composition excluding the solvent is preferably from 1% by mass to 10% by mass. The lower limit is more preferably 2% by mass or more. The upper limit is more preferably 8% by mass or less, further preferably 6% by mass or less, and particularly preferably 4% by mass or less. By setting it as such a range, both the mold release property and the surface smoothness of a pattern can be acquired.

<<Polymerization inhibitor>> The curable composition of the present invention preferably contains a polymerization inhibitor. The content of the polymerization inhibitor is preferably 0.001% by mass to 0.1% by mass, more preferably 0.005% by mass to 0.08% by mass, even more preferably 0.01% by mass to 0.05% by mass based on the mass of all the polymerizable compounds. By formulating an appropriate amount of the polymerization inhibitor, high hardening sensitivity can be maintained and viscosity change over time can be suppressed. The polymerization inhibitor may be added at the time of producing all of the polymerizable compounds, or may be added later to the hardened composition of the present invention. Specific examples of the polymerization inhibitor include 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical. Further, specific examples of the other polymerization inhibitors include the compounds described in Paragraph No. 0121 of JP-A-2012-169462, the contents of which are incorporated herein by reference.

<Interacting Agent> The curable composition of the present invention may contain a surfactant as needed. The term "surfactant" as used herein generally means a substance having a hydrophobic portion and a hydrophilic portion in a molecule and having a significant change in the properties of the interface due to a small amount of addition. The surfactant of the present invention is a substance having a hydrophobic portion and a hydrophilic portion in the molecule, and the surface tension of the curable composition is remarkably lowered by a small amount of addition, and is, for example, 1% by mass or less based on the curable composition. The amount of addition increases the surface tension of the curable composition from 40 mN/m to less than 30 mN/m. When the surfactant is contained in the curable composition of the present invention, the effect of improving the uniformity of coating or the effect of improving the mold release property can be expected. The surfactant is preferably a nonionic surfactant, preferably at least one of a fluorine-based surfactant, a Si-based surfactant, and a fluorine-Si-based surfactant, and particularly preferably a fluorine-based nonionic surfactant. Agent. Here, the "fluorine-Si-based surfactant" means a surfactant having both a fluorine-based surfactant and a Si-based surfactant.

Fluorine-based nonionic surfactants include: trade name Fluorad (Sumitomo 3M), Megafac (DIC), and Surflon (AGC SEIMI) CHEMICAL)), Unidyne (Daikin Industries), Ftergent (Neos), Eftop (Mitsubishi Materials Electronic), Polyf Polyflow (Kyotosha Chemical), KP (Shin-Etsu Chemical Industry), Troy-sol (Troy-Chemical), PolyFox (Ounova) (OMNOVA)), Capstone (DuPont), etc. The content of the surfactant in the total composition is, for example, preferably 0.01% by mass to 5% by mass, more preferably 0.1% by mass to 4% by mass, even more preferably 1% by mass to 3% by mass. The surfactant may be used alone or in combination of two or more. In the case where two or more kinds of surfactants are used, the total amount thereof is in the above range.

In the present invention, even if the aspect in which the surfactant is substantially not contained is set, a low mold release force can be achieved. The amount of the curable composition of the present invention is preferably 0.001% by mass or less, and more preferably 0.0001% by mass or less, based on the total mass of the curable composition of the present invention.

<<Other components>> The curable composition of the present invention may contain, in addition to the above components, a photosensitizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an anti-aging agent, a plasticizer, and adhesion promotion. Agent, thermal polymerization initiator, photobase generator, colorant, inorganic particles, elastomer particles, basic compound, photoacid generator, photoacid proliferator, chain transfer agent, antistatic agent, flow regulator, elimination A foaming agent, a dispersing agent, and the like. Specific examples of such a component include the compounds described in Paragraph No. 0092 to Paragraph No. 0093 and Paragraph No. 0113 to Paragraph No. 0137 of JP-A-2008-105414, the contents of which are incorporated herein by reference. . In addition, the contents of the manual of WO2011/126101, the manual of WO2013/051735, the Japanese Patent Laid-Open No. 2012-041521, and the Japanese Patent Laid-Open Publication No. 2013-093552 are incorporated herein by reference. .

<<Solvent>> The curable composition of the present invention may further contain a solvent. The content of the solvent in the curable composition of the present invention is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably substantially no solvent. Here, the term "substantially no solvent" means, for example, 1% by mass or less based on the total mass of the curable composition of the present invention. In the case where the curable composition of the present invention is applied onto a substrate by an inkjet method, when the amount of the solvent is small, the change in viscosity of the composition due to volatilization of the solvent can be suppressed, which is preferable. As described above, the curable composition of the present invention does not necessarily contain a solvent, but may be optionally added when the viscosity of the composition is finely adjusted. The type of the solvent which can be preferably used in the curable composition of the present invention is a photocurable composition for imprint or a solvent which is usually used in the photoresist, as long as the compound used in the present invention is dissolved and uniformly dispersed. And it is not specifically limited as long as it does not react with these components. Examples of the solvent which can be used in the present invention include the solvents described in Paragraph No. 0098 of JP-A-2008-105414, the contents of which are incorporated herein by reference.

<Preparation Method and Use of Curable Composition> The curable composition of the present invention can be prepared by mixing the above components. The mixing of the components is usually carried out in the range of 0 °C to 100 °C. Moreover, it is preferable to mix each component, and it filters by the filter, for example. Filtration can be carried out in multiple stages or repeated multiple times. Alternatively, the filtered solution can be filtered again. The filter is not particularly limited as long as it is used in a filter or the like. For example, a fluororesin such as polytetrafluoroethylene (PTFE), a polyamide resin such as nylon-6 or nylon-6,6, or a polyolefin resin such as polyethylene or polypropylene (PP) may be mentioned (including high Filters such as density, ultra high molecular weight). Among these raw materials, polypropylene (including high density polypropylene) and nylon are preferred. The pore diameter of the filter is, for example, suitably from about 0.003 μm to about 5.0 μm. By setting it as this range, it is possible to suppress clogging of the filter, and to reliably remove fine foreign matter such as impurities or aggregates contained in the composition. Different filters can also be combined when using filters. At this time, the filtration of the first filter may be performed only once or twice or more. In the case where two or more filters are combined by combining different filters, it is preferred that the pore diameter after the second time is the same as or smaller than the pore diameter of the first filtration. Further, the first filters of different pore sizes may be combined within the above range. The aperture here can be referred to the nominal value of the filter manufacturer. Commercially available filters are available, for example, from Pall Co., Ltd., Advantec Toyo Co., Ltd., and Entegris Co., Ltd. (formerly Japan, Mykrolis) )))) or various filters provided by KITZ Micro Filter Co., Ltd., etc.

The curable composition of the present invention preferably has a viscosity of from 5 mPa·s to 12 mPa·s at 23 °C. The lower limit is, for example, more preferably 6 mPa·s or more. The upper limit is, for example, more preferably 10 mPa·s or less, and still more preferably 8 mPa·s or less. By setting it as such a range, the inkjet discharge precision or the filling property of the uneven pattern of a mold can be improved. Further, the value of the viscosity of the present invention is a value measured by the method described in the examples below. The curable composition of the present invention preferably has a surface tension of from 27 mN/m to 33 mN/m at 23 °C. The lower limit is, for example, more preferably 28 mN/m or more, and further preferably 29 mN/m or more. The upper limit is, for example, more preferably 32 mN/m or less, and further preferably 31 mN/m or less. By setting it as such a range, inkjet discharge precision or mold release property can be improved. Further, the value of the surface tension of the present invention is a value measured by the method described in the examples below. Since the curable composition of the present invention is excellent in inkjet ejection accuracy, it is suitable as a photocurable composition for imprinting for inkjet coating.

<Pattern Forming Method> Next, the pattern forming method of the present invention will be described. The pattern forming method of the present invention forms a pattern by photoimprinting using the curable composition of the present invention. Hereinafter, a pattern forming method using the curable composition of the present invention will be specifically described. The pattern forming method of the present invention first applies the curable composition of the present invention to a substrate or a mold having a pattern. Then, the curable composition of the present invention is sandwiched between the mold and the substrate. Then, light irradiation (exposure) is performed in a state where the curable composition of the present invention is sandwiched between the mold and the substrate, and the curable composition of the present invention is cured. Finally, the mold is peeled off. The pattern of the cured product can be obtained in this way.

The method of applying the curable composition of the present invention to a substrate or a mold having a pattern by using a generally well-known coating method, for example, a dip coating method, an air knife coating method, or a curtain coating method A coating film or a droplet can be disposed on a substrate by a method, a bar coating method, a gravure coating method, an extrusion coating method, a spin coating method, a slit casting method, or an inkjet method. In particular, the curable composition of the present invention is excellent in ink jet ejection accuracy, and has excellent stability over time in ink jet ejection accuracy, and is therefore suitable for an ink jet method. In particular, it is effective in an inkjet method using an inkjet apparatus in which a curable composition is stored in a container (for example, an ink cartridge or the like) that is opened to the atmosphere.

When the curable composition of the present invention is sandwiched between the mold and the substrate, helium gas may be introduced between the mold and the substrate. By using such a method, the transmission of the quartz mold of the gas can be promoted, and the disappearance of the residual bubbles can be promoted. Further, by reducing the dissolved oxygen in the curable composition, it is possible to suppress the radical polymerization inhibition during exposure. Further, a condensable gas may be introduced between the mold and the substrate instead of the crucible. By using such a method, it is possible to further suppress the elimination of residual bubbles by condensing the introduced condensable gas and reducing the volume. The condensed gas refers to a gas which is condensed by temperature or pressure, and for example, trichlorofluoromethane or 1,1,1,3,3-pentafluoropropane or the like can be used. For the condensable gas, for example, the description of paragraph 0023 of Japanese Patent Laid-Open No. 2004-103817, and paragraph 0003 of Japanese Patent Laid-Open Publication No. 2013-254783, the contents of which are incorporated herein by reference.

At the time of exposure, it is desirable to set the exposure illuminance to a range of 1 mW/cm ² to 200 mW/cm ² . By setting the exposure time to 1 mW/cm ² or more, the exposure time can be shortened, and the productivity is improved. When the thickness is set to 200 mW/cm ² or less, the deterioration of the properties of the cured film due to the side reaction can be suppressed. good. The exposure amount is desirably set to a range of 5 mJ/cm ² to 1000 mJ/cm ² . At the time of exposure, in order to suppress the radical polymerization inhibition by oxygen, it is preferred to flow an inert gas such as nitrogen, helium, argon or carbon dioxide to control the concentration of oxygen in the atmosphere to 10 kPa or less. More preferably, the oxygen concentration in the atmosphere is 3 kPa or less, and more preferably 1 kPa or less.

The pattern forming method of the present invention may further comprise the step of hardening the curable composition of the present invention by light irradiation, and further hardening the hardened pattern as needed to further harden it. When the curable composition of the present invention is heat-cured after irradiation with light, the heating temperature is preferably from 150 ° C to 280 ° C, more preferably from 200 ° C to 250 ° C. Further, the heating time is preferably from 5 minutes to 60 minutes, and more preferably from 15 minutes to 45 minutes. Specific examples of the pattern forming method include the methods described in Paragraph No. 0125 to Paragraph No. 0136 of JP-A-2012-169462, the contents of which are incorporated herein by reference.

The pattern forming method of the present invention can be applied to a pattern inversion method. Specifically, it is a method of forming a resist pattern on a substrate to be processed having a carbon film (SOC) by the pattern forming method of the present invention. Then, after the resist pattern is coated with a Si-containing film (SOG), an upper portion of the Si-containing film is etched back to expose the resist pattern, and the plasma is exposed by oxygen plasma or the like. The exposed resist pattern is removed, thereby forming an inverted pattern of the Si-containing film. Further, the reverse pattern of the Si-containing film is used as an etching mask, and the carbon film located under the layer is etched, whereby the reverse pattern is transferred to the carbon film. Finally, the carbon film to which the reverse pattern is transferred is used as an etching mask, and the substrate is etched. Examples of such a method can be referred to Japanese Patent Laid-Open No. Hei 5-267253, Japanese Patent Laid-Open Publication No. 2002-110510, Japanese Patent Publication No. 2006-521702, Paragraph 0016 to Paragraph 0030, and Japanese Patent Special Table 2010-541193. The publication is incorporated herein by reference.

The pattern forming method of the present invention may further comprise the steps of: coating the underlying film composition on the substrate to form an underlayer film; coating the curable composition of the present invention on the surface of the underlying film; and forming the curable composition of the present invention The material and the underlayer film are irradiated with light while being sandwiched between the substrate and the patterned mold to cure the curable composition of the present invention; and the mold is peeled off. Further, after the underlayer film composition is applied onto the substrate, a part of the underlayer film composition is cured by heat or light irradiation, and then the curable composition of the present invention is applied.

The underlayer film composition contains, for example, a curable main component. The curable main agent may be thermosetting or photocurable, and is preferably thermosetting. The curable main component preferably has a molecular weight of 400 or more, and may be a low molecular compound or a polymer, preferably a polymer. The molecular weight of the curable main component is preferably 500 or more, more preferably 1,000 or more, and still more preferably 3,000 or more. The upper limit of the molecular weight is preferably 200,000 or less, more preferably 100,000 or less, and still more preferably 50,000 or less. By setting the molecular weight to 400 or more, the volatilization of the components can be more effectively suppressed. As the curable main component, for example, a polymer having a structural unit represented by the following formula as a main component can be used. [Chemical 5] In the formula, R is an alkyl group, L ¹ and L ² are each a divalent linking group, and P is a polymerizable group. n is an integer of 0 to 3. R is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group. L ^{1 is} preferably an alkylene group, more preferably an alkylene group having 1 to 3 carbon atoms, more preferably -CH ₂ -. L ^{2 is} preferably -CH ₂ -, -O-, -CHR (R is a substituent)-, and a divalent linking group containing two or more combinations of these groups. R is preferably an OH group. P is preferably a (meth)acryl fluorenyl group, more preferably an acryl fluorenyl group. n is preferably an integer of 0 to 2, more preferably 0 or 1. Commercially available products include NK Oligo EA-7140/PGMAc (manufactured by Shin-Nakamura Chemical Co., Ltd.). Further, for example, a compound described in Paragraph No. 0040 to Paragraph No. 0056 of JP-A-2009-503139, the contents of which are incorporated herein by reference.

The content of the curable main component in all the components excluding the solvent is preferably 30% by mass or more, more preferably 50% by mass or more, and still more preferably 70% by mass or more. The amount of the sclerosing main agent may be two or more. In this case, it is preferred that the total amount is in the above range.

The underlayer film composition preferably contains a solvent. A preferred solvent is a solvent having a boiling point of from 80 ° C to 200 ° C under normal pressure. The type of the solvent can be any solvent as long as it can dissolve the composition of the underlayer film, and is preferably one or more solvents having an ester structure, a ketone structure, a hydroxyl group, and an ether structure. Specifically, a preferred solvent is a single solvent or a mixed solvent selected from the group consisting of propylene glycol monomethyl ether acetate, cyclohexanone, 2-heptanone, γ-butyrolactone, propylene glycol monomethyl ether, and ethyl lactate. From the viewpoint of coating uniformity, a solvent containing propylene glycol monomethyl ether acetate is particularly preferred. The content of the solvent in the underlayer film composition is adjusted to an optimum value according to the viscosity, coating property, and target film thickness of the component excluding the solvent, and the total composition can be improved from the viewpoint of improving coatability. It is added in the range of 70% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 99% by mass or more.

The underlayer film composition may further contain at least one of a surfactant, a thermal polymerization initiator, a polymerization inhibitor, and a catalyst as other components. The compounding amount of these components is preferably 50% by mass or less based on all the components excluding the solvent. As the underlayer film composition, for example, the composition described in Paragraph No. 0017 to Paragraph No. 0054 of JP-A-2014-192178, or Paragraph No. 0017 to Paragraph No. 0068 of JP-A-2014-024322 may be used. The contents thereof are incorporated into the specification of the present application.

The underlayer film composition can be prepared by mixing the above components. Further, it is preferred to filter the respective components, for example, using a filter having a pore diameter of 0.003 μm to 5.0 μm. Filtration can be carried out in multiple stages or repeated multiple times. Alternatively, the filtered solution can be filtered again. The filter may be exemplified by the filter described in the preparation of the curable composition.

Examples of the coating method of the underlayer film composition include a dip coating method, an air knife coating method, a curtain coating method, a bar coating method, a gravure coating method, an extrusion coating method, and a spin coating method. , slit casting method, inkjet method, and the like. It is preferred to apply the underlayer film composition to the substrate and then dry it. A preferred drying temperature is from 70 ° C to 130 ° C. It is preferred to further harden by active energy, preferably heat and/or light. It is preferred to carry out heat hardening at a temperature of from 150 ° C to 250 ° C. The step of drying the solvent and the step of hardening may also be carried out simultaneously. Thus, after coating the underlayer film composition, it is preferred to cure a part of the underlayer film composition by heat or light irradiation, and then apply the curable composition of the present invention. According to this method, when the curable composition of the present invention is photocured, the underlayer film composition is completely cured, and the adhesion tends to be further improved.

The film thickness of the underlayer film is about 0.1 nm to 100 nm, preferably 1 nm to 20 nm, and more preferably 2 nm to 10 nm, depending on the application to be used. Alternatively, the underlying film composition can be applied by multiple coating. The resulting underlayer film is preferably as flat as possible.

The substrate (substrate or support) can be selected according to various uses, such as quartz, glass, optical film, ceramic material, vapor deposited film, magnetic film, reflective film, metal substrate such as Ni, Cu, Cr, Fe, paper, a polymer substrate such as a polyester film, a polycarbonate film or a polyimide film, a thin film transistor (TFT) array substrate, and an electrode plate of a plasma display panel (Plasma Display Panel (PDP)), Indium Tin Oxide (ITO) or conductive substrate such as metal, insulating substrate such as glass or plastic, tantalum, tantalum nitride, polycrystalline germanium, tantalum oxide, amorphous germanium, spin on glass (Spin On Glass, The substrate for semiconductor production such as SOG) or spin on carbon (SOC) is not particularly limited.

<Pattern> The pattern formed by the pattern forming method of the present invention as described above can be used as a permanent film used in a liquid crystal display device (LCD) or the like, or an etching resist for semiconductor processing. Further, the pattern of the present invention can be used to form a grid pattern on a glass substrate of a liquid crystal display device, and a polarizing plate having less reflection or absorption and having a large screen size (for example, 55 Å or more) can be manufactured at low cost. For example, a polarizing plate described in Japanese Laid-Open Patent Publication No. 2015-132825 or WO2011/132649 can be manufactured. Furthermore, 1吋 is 25.4 mm. For example, it can be preferably used for: semiconductor integrated circuit, microelectromechanical system (MEMS), recording medium such as optical disk and magnetic disk, light receiving device such as solid-state imaging device, light-emitting device such as LED or organic EL, liquid crystal display device (LCD) Optical components such as optical gratings, diffraction gratings, stereo holograms, optical waveguides, optical filters, microlens arrays, thin film transistors, organic transistors, color filters, anti-reflection films, polarizers, polarizing devices, Components for flat panel displays such as optical films and pillars, nano biocomponents, immunoassay wafers, deoxyribonucleic acid (DNA) separation wafers, and microreactors for micronization using photonic liquid crystals and block copolymers Guided pattern of directed self-assembly (DSA), and the like. Further, the pattern obtained by using the curable composition of the present invention is also excellent in solvent resistance. The pattern is preferably high in resistance to a solvent, and it is particularly preferable that the film thickness is not changed when immersed in a solvent used in a usual substrate production step, for example, a N-methylpyrrolidone solvent at 25 ° C for 10 minutes. The pattern formed by the pattern forming method of the present invention is particularly useful as an etching resist. When the curable composition of the present invention is used as an etching resist, a nano-scale fine pattern is formed on the substrate by the pattern forming method of the present invention. Thereafter, etching is performed using hydrogen fluoride or the like in the case of wet etching, and etching is performed using an etching gas such as CF ₄ in the case of dry etching, whereby a desired pattern can be formed on the substrate. The curable composition of the present invention is excellent in etching resistance to dry etching using carbon fluoride or the like.

<Element Manufacturing Method> The element manufacturing method of the present invention includes the pattern forming method described above. That is, after the pattern is formed by the method described above, the element is manufactured by applying the method used in manufacturing various elements. The pattern may also be included in the component as a permanent film. Alternatively, the substrate may be etched using the pattern as an etch mask. For example, the pattern is subjected to dry etching as an etch mask to selectively remove the upper portion of the substrate. The component can also be fabricated by repeating such treatment on the substrate. The element may be a semiconductor element such as a large-scale integrated circuit (LSI) or an optical element such as a liquid crystal display device. [Examples]

The invention is more specifically illustrated by the following examples. The materials, the amounts used, the ratios, the processing contents, the processing order, and the like shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

(Synthesis Example 1) Synthesis of fluorine-containing acrylate (B-1) [Chemical 6] For a solution obtained by dissolving 100 g (0.89 mol) of potassium t-butoxide in 700 mL of tert-butanol, while maintaining the internal temperature below 30 ° C in a water bath, 316.9 g (0.87 mol) was added dropwise. 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol, an alkoxide solution was prepared. For the mixture of 171.7 g (0.88 mol) of butyl bromoacetate and 300 mL of tributanol, the previously prepared alkoxide solution was added dropwise while maintaining the internal temperature below 30 ° C in a water bath. After the completion of the dropwise addition, the mixture was stirred at 25 ° C for 1 hour, and then 500 mL of n-hexane and 500 mL of 0.1 mol/L hydrochloric acid water were added for liquid separation extraction. The organic layer was washed twice with 500 mL of water and concentrated under reduced pressure to give Intermediate (1-1) (yield 406.1 g, yield 97.6%). For the solution of 382.6 g (0.80 mol) of intermediate (1-1) and 800 mL of methanol, after adding 154.3 g of a 28% by mass sodium methoxide solution, 23.9 g (0.63 mol) of sodium tetrahydroborate was added. The reaction was carried out at 40 ° C for 4 hours. After the completion of the reaction, the reaction solution was gradually added to 1 L of 2 mol/L hydrochloric acid water to decompose excess sodium tetrahydroborate, and then 300 mL of ethyl acetate and 800 mL of n-hexane were added for liquid separation extraction. The organic layer was washed with 1000 mL of water and concentrated under reduced pressure. The obtained concentrate was distilled under reduced pressure to give 326.2 g of intermediate (1-2) (b.p.: 80 to 84.degree. C., 0.40 kPa, yield 99.9%). After adding 100.3 g (0.96 mol) of triethylamine to a solution of 326.2 g (0.799 mol) of intermediate (1-2) and 800 mL of toluene, the internal temperature was maintained in an ice bath. At 15 ° C or less, 83.2 g (0.92 mol) of acrylonitrile chloride was added dropwise. After completion of the dropwise addition, the mixture was stirred for 2 hours, and then 800 mL of a 2% by mass aqueous sodium hydrogencarbonate solution was added for liquid separation extraction. The organic layer was washed twice with 800 mL of 1 mol/L hydrochloric acid water, followed by washing with 800 mL of water, and then added 38 mg of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo The free radical (4-HO-TEMPO) was concentrated under reduced pressure. 380 mg of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-BzO-TEMPO) benzoate was added to the obtained concentrate for distillation under reduced pressure to obtain 230.0 g. Target fluorine-containing acrylate (B-1) (boiling point: 107 ° C / 0.67 kPa, yield 62.3%).

(Synthesis Example 2) Synthesis of fluorine-containing acrylate (B-2) [Chemical 7] For 364.2 g (1.0 mol) 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol, 124.2 g (1.1 mol) A mixture of chloroacetic chloride and 1000 mL of ethyl acetate was added dropwise with 87.0 g (1.1 mol) of pyridine while maintaining the internal temperature below 15 ° C in an ice bath. After the completion of the dropwise addition, the reaction was carried out at 15 ° C for 2 hours, and then 500 mL of water was added for liquid separation extraction. The organic layer was washed with 500 mL of a 2% by mass aqueous sodium hydrogencarbonate solution, followed by 500 mL of 0.1 mol/L hydrochloric acid, and concentrated under reduced pressure to give 432.8 g of Intermediate (2-1) (yield: 98.1%). Add 43.3 g (0.6 mol) acrylic acid to a mixture of 220.3 g (0.5 mol) intermediate (2-1), 82.9 g (0.6 mol) potassium carbonate and 500 mL N-methylpyrrolidone And 8.3 g (0.05 mol) potassium iodide, and reacted at 25 ° C for 3 hours. After the reaction was completed, 500 mL of n-heptane, 500 mL of n-hexane, and 500 mL of water were added for liquid separation extraction. After the organic layer was washed twice with 500 mL of 0.1 mol/L hydrochloric acid water, 22 mg of 4-HO-TEMPO was added and concentrated under reduced pressure. 220 mg of 4-BzO-TEMPO was added to the obtained concentrate for distillation under reduced pressure to obtain 219.0 g of the target fluorine-containing acrylate (B-2) (boiling point: 124 ° C / 0.67 kPa, yield: 92.0%).

(Synthesis Example 3) Synthesis of fluorine-containing acrylate (B-3) [Chemical 8] For 84.0 g (0.20 mol) 7,7,8,8,9,9,10,10,11,11,12,12,12-tridecafluoro-1-dodecanol, 24.3 g (0.24 mol) A mixture of triethylamine and 500 mL of ethyl acetate was added dropwise 21.7 g (0.24 mol) of acrylonitrile chloride while maintaining the internal temperature below 10 ° C in an ice bath. After the completion of the dropwise addition, the mixture was reacted at room temperature for 2 hours, and then 500 mL of water was added for liquid separation extraction. The organic layer was washed with 500 mL of a 2% by mass aqueous sodium hydrogencarbonate solution, followed by 500 mL of 1 mol/L hydrochloric acid water, and finally 500 mL of pure water, and then 8 mg of 4-HO-TEMPO was added thereto to concentrate under reduced pressure. 80 mg of 4-BzO-TEMPO was added to the obtained concentrate for distillation under reduced pressure to obtain 69.8 g of the target fluorine-containing acrylate (B-3) (boiling point: 111 ° C / 0.67 kPa, yield 73.6%).

<Preparation of Photocurable Composition for Imprinting> The (meth) acrylate (A) having no fluorine atom and the (meth) acrylate containing fluorine atom at a mass ratio shown in Table 1 below (B) The photopolymerization initiator (C) and the non-polymerizable compound (D) having a polyoxyalkylene group structure are mixed and further added as a polymerization inhibitor so as to be 200 ppm (0.02% by mass) based on the curable composition. After 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical (manufactured by Tokyo Chemical Industry Co., Ltd.), it was filtered with a 0.1 μm PTFE filter to prepare the imprint of the present invention. The curable composition X-1 to the curable composition X-6 for imprint. In addition, the comparative hardening composition R-1 to the comparative hardening composition R-4 are also used in addition to the comparative compound (S) instead of the fluorine atom-containing (meth) acrylate (B). In the curable composition of the invention, the comparative curable composition R-1 to the comparative curable composition R-4 were prepared in the same manner. The surface tension and viscosity at 23 ° C of the curable composition for imprint of the present invention and the curable composition for comparison were measured. Also listed in Table 1. The surface tension was measured using a surface tension meter CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd., by immersing the lower end of the platinum plate in the measurement sample at 23 ° C ± 0.2 ° C. Further, the platinum plate is a platinum plate obtained by red-heating with an alcohol lamp before the measurement to clean the surface. The viscosity is the E-type rotary viscometer RE85L manufactured by Toki Sangyo Co., Ltd., the standard cone rotor (1°34'×R24), the rotation speed is set to 50 rpm, and the temperature of the sample cup is adjusted to 23 °C ± 0.1. Measured at °C.

[Table 1]

The details of the (meth) acrylate (A), the photopolymerization initiator (B), the non-polymerizable compound (D), and the comparative compound (S) used in the examples and the comparative examples are as follows.

<(A) fluorinated atom-free (meth) acrylate (A)> A-1: Dodecyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate LA) A-2: Neopentyl glycol Diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate NP-A) A-3: m-xylene diacrylate (synthesized from α,α'-dichlorom-xylene and acrylic acid) ] <Photopolymerization initiator (C)> C-1: Irgacure 819 (manufactured by BASF) <Non-polymerizable compound (D) having a polyoxyalkylene structure> D-1: Polypropylene glycol (quantitative molecular weight 700, manufactured by Wako Pure Chemical Industries, Ltd.) <Comparative compound (S)> S-1: Acrylic acid-1H, 1H-undecfluorohexyl ester (Syracuse Laboratories (SynQuest Laboratories)) S- 2: Acrylic acid-1H, 1H, 2H, 2H-heptadecafluorodecyl ester (manufactured by Tokyo Chemical Industry Co., Ltd.) S-3: 3-(perfluorohexyl)propanol acrylate (made by SynQuest Laboratories) S -4:2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

<Inkjet ejection accuracy> The inkjet printer DMP-2831 (manufactured by Fujifilm Dimatix) was used to adjust the temperature to a temperature of 1 pl per nozzle to adjust the temperature to 23 ° C. The material was ejected onto the crucible wafer and coated on the crucible wafer in such a manner that the droplets were arranged in a square of 100 μm intervals. The 2500 points of 5 mm square of the applied substrate were observed, and the deviation from the square arrangement was measured to calculate the standard deviation σ. The inkjet ejection accuracy was evaluated by A to D as follows. A: σ < 3 μm B: 3 μm ≦ σ < 5 μm C: 5 μm ≦ σ < 10 μm D: 10 μm ≦ σ

<Evaluation of the stability after three months of storage] The state in which the curable composition for photoimprint is filled in a material cartridge for an ink jet printer DMP-2831 at a temperature of 23 ° C and a humidity of 50 ° C After three months of storage in the environment, the inkjet ejection accuracy was evaluated.

[Table 2]

As shown by the results of the table, the curable compositions of Examples 1 to 6 did not show deterioration in ink jet ejection accuracy before the comparison with the time-lapse test and after three months, and both showed good performance. In addition, after each of the hardenable compositions was ink-jet coated on the tantalum wafer as described above, a quartz mold (line/gap=1/1, line width 30 nm, groove depth 60 nm, line edge roughness 3.0) was obtained. In the contact with nm, the quartz mold was released from the quartz mold side by using a high-pressure mercury lamp at a condition of 100 mJ/cm ² , and the curable composition of Examples 4 to 6 containing the non-polymerizable compound (D) was obtained. The mold release property is particularly excellent. On the other hand, in the curable compositions of Comparative Examples 1 to 4, the inkjet ejection accuracy was remarkably deteriorated after three months.

no

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Claims (9)

A photocurable composition for imprinting comprising: a (meth) acrylate (A) having no fluorine atom, a (meth) acrylate (B) having a fluorine atom, and a photopolymerization initiator (C) And the fluorine atom-containing (meth) acrylate (B) is represented by the following general formula (I), In the formula, R ^f represents a fluorine-containing alkyl group having 1 to 9 carbon atoms in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, and L represents a single bond, -O-, -OC(=O)- or -C(= O)O-, R ¹ represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 8. When L is a single bond, it represents an integer of 3 to 8. The photocurable composition for imprint according to claim 1, wherein the fluorine atom-containing (meth) acrylate (B) has a boiling point of from 100 ° C to 200 ° C at a pressure of 0.67 kPa. The photocurable composition for embossing according to the first or second aspect of the invention, wherein in the formula (I), R ^f is from 40% to 100% of a hydrogen atom of the alkyl group via fluorine A fluorine-containing alkyl group having 1 to 9 carbon atoms substituted by an atom. The photocurable composition for imprinting according to the above aspect of the invention, wherein in the formula (I), R ^f is a perfluoroalkyl group and carbon having a carbon number of 4 to 6. a group of 1 to 3 alkylene groups. The photocurable composition for imprint according to the first or second aspect of the invention, wherein the photocurable photocurable composition contains 1% by mass to 5% by mass of the fluorine atom. (Meth) acrylate (B). The photocurable composition for imprint according to the first or second aspect of the invention, further comprising 1% by mass to 5% by mass of the non-polymerizable compound (D) having a polyoxyalkylene group structure. The photocurable composition for imprinting according to claim 1 or 2, which has a viscosity of 5 mP·s to 12 mP·s at 23 ° C and a surface tension of 27 mN/m to 33 mN/m. A pattern forming method comprising the steps of: applying a photocurable composition for imprinting according to any one of claims 1 to 7 to a substrate or having a pattern by an inkjet method; The photocurable composition for imprinting is sandwiched between the mold and the substrate; and the light is irradiated in a state where the photocurable photocurable composition is sandwiched between the mold and the substrate, so that the light is irradiated The photocurable composition for embossing is cured; and the mold is peeled off. A device manufacturing method comprising the steps of etching a substrate using a pattern produced by the pattern forming method according to claim 8 of the patent application as a mask.