JP5346787B2 - Curable resin composition and cured product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition having high definition and capable of forming a resin pattern in which occurrence of a crack is suppressed, and to provide a cured product prepared by curing such a curable resin composition. <P>SOLUTION: The curable resin composition includes (A) a polyfunctional epoxy resin which is solid at ordinary temperatures, (B) a cationic initiator, and (C) a (meth)acrylic monomer. The (C) (meth)acrylic monomer has two or more ethylenic unsaturated bonds coupled with a linear alkylene chain which may contain an oxygen atom. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a curable resin composition capable of forming a fine resin by forming a resin pattern using a photolithography technique, and a cured product obtained by curing the resin composition.

  In recent years, with the increasing demand for downsizing in the field of electronic components and ultra-fine processing represented by the nozzles of print heads in inkjet printers, a resin pattern with a resolution of several μm by photolithography technology. There is a demand for a curable resin composition that can be formed with a high aspect ratio. By using such a curable resin composition, the cured product can be used to form an etching mask that can form a high-definition circuit on the substrate, or to form a model having an ultrafine structure. can do.

  However, a conventional curable resin composition containing a novolak resin and diazonaphthoquinone, which is a photoacid generator, forms a resin pattern having a sufficient thickness and high resolution, that is, a resin pattern having a high aspect ratio. It was difficult. This is because the diazonaphthoquinone type photoacid generator has high absorption in the near-ultraviolet region used for exposure, the light exposure intensity differs greatly between the top and bottom of the film, and the shape of the resulting resin pattern is tapered. Or to distort.

  On the other hand, by studying a curable resin composition containing an epoxy resin and an acid generator, a curable resin composition having a high aspect ratio and capable of realizing high resolution has been proposed.

  Such a curable resin composition comprises, for example, an epoxy functional novolak resin, a cationic photopolymerization initiator such as a triarylsulfonium salt, and a diluent capable of reacting with an epoxy functional group. It consists of a photocurable composition that is difficult to peel off (Patent Document 1), a polyfunctional bisphenol A formaldehyde-novolak resin, triphenylsulfonium hexafluoroantimonate that is an acid generator, and cyclopentanone as a solvent. A photocurable composition that can be formed (Patent Document 2) has been proposed.

  Furthermore, if a photosensitive (curable) resin composition is prepared by combining a polyfunctional epoxy resin and a specific acid generator, and a resin pattern is formed using this curable resin composition, with high sensitivity, It has been reported that a resin pattern having a shape with a small volume shrinkage during heat curing and a high aspect ratio can be formed (Patent Document 3).

Japanese Patent Publication No. 7-78628 US Pat. No. 6,391,523 Japanese Patent Laid-Open No. 2005-55865

  However, as in Patent Documents 1 and 2, the conventional curable resin composition using a polyfunctional epoxy resin such as a novolak resin has a low sensitivity of the cationic polymerization initiator contained therein, and therefore contains a large amount of initiator. Therefore, there is a problem that the mask pattern cannot be faithfully reproduced as a resin pattern.

  In this regard, according to the curable resin composition described in Patent Document 3, a high sensitivity effect can be obtained by employing a specific acid generator as a cationic polymerization initiator, thereby having high resolution. A resin pattern can be formed. However, since this curable resin composition forms a resin pattern by crosslinking a polyfunctional epoxy resin, the formed resin pattern has a high internal stress. For this reason, there was a tendency for the resin pattern to easily crack (crack), and there was room for improvement.

  The present invention has been made in view of the above situation, a curable resin composition capable of forming a resin pattern with high resolution and suppressed generation of cracks, and such It aims at providing the hardened | cured material formed by hardening | curing curable resin composition.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have further developed a specific structure for a curable resin composition containing a polyfunctional epoxy resin solid at room temperature and a cationic polymerization initiator. It has been found that the above-mentioned problems can be solved by adding the (meth) acrylic monomer, and the present invention has been completed.

  The first aspect of the present invention is a curable resin composition comprising (A) a polyfunctional epoxy resin that is solid at normal temperature, (B) a cationic polymerization initiator, and (C) a (meth) acrylic monomer. The (C) (meth) acrylic monomer has two or more ethylenically unsaturated bonds connected to each other by a chain-like alkylene chain which may contain an oxygen atom.

  The second aspect of the present invention is a cured product obtained by curing the curable resin composition of the first aspect of the present invention.

  According to the present invention, a curable resin composition capable of forming a resin pattern having high resolution and suppressed generation of cracks, and such a curable resin composition are cured. A cured product is provided.

<Curable resin composition>
First, the curable resin composition of this invention is demonstrated. The curable resin composition of the present invention has a property of being cured by crosslinking by irradiating active energy rays such as ultraviolet rays, a negative type photoresist, a negative type dry film resist, and a micro resin molding having a fine structure. Etc. are preferably used. That is, the curable resin composition of the present invention is preferably used for applications in which a resin pattern is formed by irradiation with active energy rays such as ultraviolet rays. Here, the resin pattern is a cured product obtained by curing the curable resin composition of the present invention into a desired shape by a photolithography method.

  When the curable resin composition of the present invention is used as an application such as photoresist or fine resin molding, first, the curable resin composition of the present invention is applied to the surface of a substrate on which a resin pattern is to be formed. The solvent component contained in the resin composition is volatilized to produce a resin film. Next, a photomask having a shape of a pattern to be formed is placed on the surface of the resin film and irradiated with active energy rays such as ultraviolet rays. Thereafter, a resin pattern is formed on the surface of the base material through a development step and, if necessary, a post-bake step. This resin pattern is used as an etching mask or a fine resin molding.

  When the curable resin composition of the present invention is used as a dry film, the curable resin composition of the present invention is applied to the surface of a substrate such as a resin sheet, and then the solvent component contained in the curable resin composition is volatilized. Thus, a resin film to be a dry film is produced. Thereafter, the produced dry film is adhered to the surface of the base material on which the resin pattern is to be formed, and patterned with active energy rays in the same manner as described above. Thereafter, a resin pattern is formed on the surface of the base material through a development step and, if necessary, a post-bake step.

  The curable resin composition of the present invention includes (A) a polyfunctional epoxy resin that is solid at room temperature, (B) a cationic polymerization initiator, and (C) a (meth) acrylic monomer. Next, these components will be described.

[(A) Multifunctional epoxy resin]
The polyfunctional epoxy resin used in the present invention is a resin having three or more epoxy groups in one molecule, and a sufficient number of epoxy groups to cure the resin film formed from the curable resin composition. Any epoxy resin may be used as long as it is an epoxy resin containing in a molecule. As such a polyfunctional epoxy resin, a phenol novolak type epoxy resin, an ortho cresol novolak type epoxy resin, a triphenyl type novolak type epoxy resin, and a bisphenol A novolak type epoxy resin are preferable.

  The functionality which is the number of epoxy groups contained in one molecule of the polyfunctional epoxy resin is preferably 3 or more, and more preferably 4-12. When the functionality of the polyfunctional epoxy resin is 3 or more, a resin pattern having a high aspect ratio and resolution can be formed, and preferably, the functionality of the polyfunctional epoxy resin is 12 or less. Resin synthesis is easy to control, and it is preferable because the internal stress of the resin pattern can be prevented from becoming excessively large.

  The mass average molecular weight of the polyfunctional epoxy resin is preferably 700 to 5000, and more preferably 1000 to 4000. The mass average molecular weight of the polyfunctional epoxy resin is preferably 700 or more, which is preferable in that the curable resin composition can be prevented from flowing heat before being cured by irradiation with active energy rays, and the mass of the polyfunctional epoxy resin. An average molecular weight of 5,000 or less is preferable in that an appropriate dissolution rate during patterning development can be obtained.

  The polyfunctional epoxy resin used in the present invention is solid at room temperature. Since the polyfunctional epoxy resin is solid at room temperature, it has excellent film formability by spin coating, and is suitable for handling in a series of patterning processes of exposure, PEB, and development. During PEB, the uncured resin film formed from the curable resin composition can be prevented from flowing heat, and the aspect ratio and resolution of the resin pattern can be increased. In this respect, the curable resin composition of the present invention is different from the curable resin composition for three-dimensional modeling, which generally uses a polyfunctional epoxy resin that is liquid at room temperature. The term “three-dimensional modeling” as used herein refers to a technique for irradiating a curable resin composition with a laser beam to form a relatively large three-dimensional object of several centimeters or more, and the curable resin composition of the present invention. This is different from the technique for forming a three-dimensional object having a fine structure as produced.

  Examples of such a polyfunctional epoxy resin include an 8-functional bisphenol A novolac type epoxy resin (“jER157S70” manufactured by Japan Epoxy Resin Co., Ltd.) and an average 6.4 functional bisphenol A novolac type epoxy resin (“DIC manufactured by DIC Corporation”). Epicron N-885 "), an average 5.6 functional bisphenol A novolac type epoxy resin (" Epicron N-865 "manufactured by DIC Corporation), and the like are particularly preferable.

  The polyfunctional bisphenol A novolac type epoxy resin is represented, for example, by the following general formula (4).

（上記一般式（４）中、Ｒ^１〜Ｒ^６は、水素原子又はメチル基である。また、ｘは、０又は正の整数であり、好ましくは１〜１０の整数であり、より好ましくは１〜５の整数である。なお、上記式（４）中のエポキシ基は、他のビスフェノールＡ型エポキシ樹脂又はビスフェノールＡノボラック型エポキシ樹脂と反応し、結合していてもよい。）

(In the general formula (4), R ^{1 to} R ⁶ are a hydrogen atom or a methyl group. Further, x is 0 or a positive integer, preferably an integer of 1 to 10, more preferably. It is an integer of 1 to 5. In addition, the epoxy group in the above formula (4) may react with another bisphenol A type epoxy resin or bisphenol A novolac type epoxy resin and be bonded.

  The softening point of the polyfunctional epoxy resin is not particularly limited as long as it is solid at room temperature as described above. In particular, when a dry film resist is formed with the curable resin composition of the present invention, it is not preferable to soften at about room temperature (about 40 ° C.), and it is necessary to soften by heating during lamination. From this point, the softening point of the polyfunctional epoxy resin is preferably about 50 to 100 ° C, and more preferably about 60 to 80 ° C.

  70-95 mass% is preferable and, as for content of the polyfunctional epoxy resin in curable resin composition, it is more preferable that it is 75-93 mass%. If the density | concentration of the polyfunctional epoxy resin in curable resin composition is 70 mass% or more, since sufficient intensity | strength can be provided to the hardened | cured material obtained by hardening, it is preferable. Moreover, if the density | concentration of the polyfunctional epoxy resin in curable resin composition is 95 mass% or less, since sufficient sensitivity can be obtained when photocuring a curable resin composition, it is preferable. In addition, the said content is a thing when the curable resin composition does not contain the solvent component mentioned later. Therefore, when the curable resin composition includes a solvent component described later, the content of the polyfunctional epoxy resin after removing the mass of the solvent component may be within the above range.

[(B) Cationic polymerization initiator]
Next, the cationic polymerization initiator will be described. The cationic polymerization initiator used in the present invention generates cations upon irradiation with active energy rays such as ultraviolet rays, far ultraviolet rays, excimer laser light such as KrF and ArF, X-rays and electron beams, and the cations are polymerized. A compound that can be an initiator.

  Such a cationic polymerization initiator is represented by the following general formula (5), for example.

（上記一般式（５）中、Ｒ^７及びＲ^８は、それぞれ独立に、水素原子、ハロゲン原子、酸素原子若しくはハロゲン原子を含んでもよい炭化水素基、又は置換基が結合してもよいアルコキシ基を表し、Ｒ^９は、その水素原子の１つ又はそれ以上がハロゲン原子又はアルキル基により置換されてもよいｐ−フェニレン基を表し、Ｒ^１０は、水素原子、酸素原子又はハロゲン原子を含んでもよい炭化水素基、置換基を有してもよいベンゾイル基、置換基を有してもよいポリフェニル基を表し、Ａ⁻は、オニウムイオンの対イオンを表す。）

(In the general formula (5), R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group that may contain an oxygen atom or a halogen atom, or an alkoxy group to which a substituent may be bonded. R ⁹ represents a p-phenylene group in which one or more of its hydrogen atoms may be substituted with a halogen atom or an alkyl group, and R ¹⁰ may contain a hydrogen atom, an oxygen atom or a halogen atom. good hydrocarbon group, an optionally substituted benzoyl group, represents an polyphenyl group which may have a substituent, a ^- represents a counter ion of onium ions).

（上記一般式（６）中、Ｒｆは、水素原子の８０％以上がフッ素原子で置換されたアルキル基を表す。ｂは、その個数を表し、１〜５の整数である。ｂ個のＲｆは、それぞれ同一であっても異なっていてもよい。） In the general formula (5), as A ⁻ , specifically, SbF ₆ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , BF ₄ ⁻ , SbCl ₆ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , CH ₃ SO _{^{3 -, FSO 3 -, F}} 2 PO 2 -, p- toluenesulfonate, nonafluorobutane sulfonate, adamantane carboxylate, tetraaryl borate, a fluorinated alkyl fluorophosphate anion represented by the following general formula (6) Illustrated.

(In the general formula (6), Rf represents an alkyl group in which 80% or more of the hydrogen atoms are substituted with fluorine atoms. B represents the number and is an integer of 1 to 5. b Rf May be the same or different.)

  Examples of such cationic initiators include 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4- Fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-methylphenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4- (β-hydroxyethoxy) phenyl) sulfonium hexafluoroantimonate, 4- (2 Methyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (3-methyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4 -(2-Fluoro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-methyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate 4- (2,3,5,6-tetramethyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2,6-dichloro-4-benzoyl) Phenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2,6-dimethyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2, 3-dimethyl-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-methyl-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (3-Methyl-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-fluoro-4-benzoylphenylthio) phenylbis (4-chloro Enyl) sulfonium hexafluoroantimonate, 4- (2-methyl-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2,3,5,6-tetramethyl-4- Benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2,6-dichloro-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2, 6-dimethyl-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2,3-dimethyl-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfoniu Hexafluoroantimonate, 4- (2-chloro-4-acetylphenylthio) phenyldiphenylsulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methylbenzoyl) phenylthio) phenyldiphenylsulfonium hexafluoroantimonate 4- (2-chloro-4- (4-fluorobenzoyl) phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methoxybenzoyl) phenylthio) phenyldiphenylsulfonium hexafluoroantimonate 4- (2-chloro-4-dodecanoylphenylthio) phenyldiphenylsulfonium hexafluoroantimonate, 4- (2-chloro-4-acetylphenylthio) phenylbis (4 -Fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methylbenzoyl) phenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-Fluorobenzoyl) phenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methoxybenzoyl) phenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoro Antimonate, 4- (2-chloro-4-dodecanoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-acetylphenylthio) phenylbis (4 Chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methylbenzoyl) phenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4- Fluorobenzoyl) phenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4- (4-methoxybenzoyl) phenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-Chloro-4-dodecanoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfo Um hexafluorophosphate, 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfonium tetrafluoroborate, 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfonium perchlorate, 4- (2-chloro -4-benzoylphenylthio) phenyldiphenylsulfonium trifluoromethanesulfonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluorophosphate, 4- (2-chloro-4-benzoyl) Phenylthio) phenylbis (4-fluorophenyl) sulfonium tetrafluoroborate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium Perchlorate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium trifluoromethanesulfonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) Sulfonium p-toluenesulfonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium camphorsulfonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluoro) Phenyl) sulfonium nonafluorobutanesulfonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium hexafluorophosphate, 4- (2-chloro-4-benzoylphenyl) E) phenylbis (4-chlorophenyl) sulfonium tetrafluoroborate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-chlorophenyl) sulfonium perchlorate, 4- (2-chloro-4-benzoylphenylthio) ) Phenylbis (4-chlorophenyl) sulfonium trifluoromethanesulfonate, diphenyl [4- (phenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate, diphenyl [4- (p-terphenylthio) phenyl] sulfonium hexafluoroantimonate And diphenyl [4- (p-terphenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate. Among these compounds, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate (manufactured by ADEKA Corporation, Adekaoptomer SP-172), diphenyl [4- (Phenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate (manufactured by San Apro, CPI-210S), diphenyl [4- (p-terphenylthio) phenyl] sulfonium hexafluoroantimonate, diphenyl [4- (p -Terphenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate (manufactured by San Apro, HS-1PG) is preferred.

  0.1-10 mass% is preferable and, as for content of the cationic polymerization initiator in curable resin composition, it is more preferable that it is 0.5-5 mass%. If the content of the cationic polymerization initiator in the curable resin composition is 0.1% by mass or more, it is preferable because the curing time of the curable resin composition by active energy ray exposure can be made appropriate. Moreover, if the content of the cationic polymerization initiator in the curable resin composition is 10% by mass or less, the developability after exposure with active energy rays can be improved, which is preferable. In addition, the said content is a thing when the curable resin composition does not contain the solvent component mentioned later. Therefore, when the curable resin composition includes a solvent component described later, the content of the cationic polymerization initiator after removing the mass of the solvent component may be within the above range.

[(C) (Meth) acrylic monomer]
Next, the (meth) acryl monomer will be described. The (meth) acrylic monomer used in the present invention has two or more ethylenically unsaturated bonds connected to each other by a chain-like alkylene chain that may contain an oxygen atom. In the present invention, the term “(meth) acryl” is used to mean “acryl and / or methacryl”.

  In the curable resin composition of the present invention, a cation generated from the cationic polymerization initiator upon irradiation with active energy rays polymerizes an epoxy group contained in the polyfunctional epoxy resin to become a cured product. Here, since the (meth) acrylic monomer hardly causes a polymerization reaction depending on the cationic polymerization initiator, the (meth) acrylic monomer used in the present invention undergoes such a polymerization reaction during irradiation with active energy rays. Not directly involved. Therefore, a (meth) acryl monomer is not usually added to a curable resin composition containing an epoxy monomer such as a polyfunctional epoxy resin and a cationic polymerization initiator. However, the present inventors surprisingly added a (meth) acrylic monomer to a curable resin composition containing a polyfunctional epoxy resin and a cationic polymerization initiator. It was found that the internal stress in (2) was relieved, thereby suppressing the occurrence of cracks in the cured product. The present invention has been completed based on such findings.

  This will be described in more detail. Conventionally, when a curable resin composition containing a polyfunctional epoxy resin and a cationic polymerization initiator is cured by irradiation with active energy rays, the cured product becomes a cured product having a high hardness and a resin pattern that gives a high aspect ratio. Was known to be. Therefore, the cured product has been preferably used for forming a fine resin having a fine structure such as an etching mask for producing a high-definition electronic circuit or a print head for an ink jet printer.

  However, a cured product obtained by curing a conventionally used curable resin composition has a high hardness, and at the same time, has a high internal stress accompanying a curing shrinkage, and thus may cause a crack. For example, when a cured product is used as a print head for an ink jet printer, the cured product with cracks may cause ink ejection failure and cannot be used as a product. For this reason, the crack has become one of the factors that reduce the product yield.

  In this regard, in the curable resin composition of the present invention, as described above, while the active energy rays are irradiated, the epoxy groups contained in the polyfunctional epoxy resin are successively polymerized by the cations generated by the light irradiation, The (meth) acrylic monomer hardly contributes to the polymerization reaction at the time of irradiation with active energy rays, and many exist as the monomer. As a result, in the cured product after irradiation with active energy rays, it is suppressed that the network structure formed by polymerization of the polyfunctional epoxy resin is formed at a high density over the entire cured product, It exists in a state of having a relatively high degree of freedom inside the cured product. Thus, since the (meth) acryl monomer present as a monomer plays a role as a buffer in the cured product, the cured product after irradiation with active energy rays has a relatively small internal stress.

  Thereafter, the (meth) acrylic monomer contained in the cured product is cured by causing a polymerization reaction over time or by post-exposure heating (PEB) or post-bake treatment after irradiation with active energy rays. As a result, a polymer of (meth) acrylic monomer exists like a filler in the network structure formed by the polymerization of polyfunctional epoxy resin inside the cured product after polymerization of (meth) acrylic monomer. It is guessed that it is in the state. In this way, the cured product after curing the curable resin composition of the present invention has a (meth) acrylic monomer as a polymer therein, so that the strength is maintained, while the polyfunctional epoxy resin. It is suppressed that the network structure formed as a result of the polymerization is excessively densely formed over the entire cured product. Therefore, the cured product obtained by curing the curable resin composition of the present invention has a high aspect ratio because internal stress is suppressed while maintaining the high aspect ratio that is characteristic of the cured product of the polyfunctional epoxy resin. However, the occurrence of cracks is suppressed.

In addition, as mentioned above, in the curable resin composition of this invention, in order to harden a (meth) acryl monomer, the thermal energy by post-baking with time or after irradiation of an active energy ray is used. That is, the (meth) acryl monomer is thermally polymerized. Of course, if a radical polymerization initiator that generates radicals upon irradiation with active energy rays is added to the curable resin composition, the (meth) acrylic monomer can be polymerized simultaneously with the irradiation with active energy rays. However, this is not preferable because the resolution of the obtained cured product is lowered. The reason why the resolution of the cured product is lowered in this way is that when the active energy ray is irradiated onto the resin film made of the curable resin composition, the generated radical moves outside the irradiation range of the active energy ray ( This is probably because the (meth) acrylic monomer is polymerized and the reproducibility of the mask pattern is deteriorated.
As a polymerization initiator component in the curable resin composition of the present invention, in addition to the cationic polymerization initiator (B), a radical polymerization initiator may be included. 90% by mass or more is preferably (B) a cationic polymerization initiator, more preferably 95% by mass or more is (B) a cationic polymerization initiator, and 100% by mass is (B) a cationic polymerization initiator. Most preferably it is.

  As described above, the (meth) acrylic monomer used in the curable resin composition of the present invention has two or more ethylenically unsaturated bonds connected to each other by a chain-like alkylene chain that may contain an oxygen atom. Is. Here, two or more ethylenically unsaturated bonds are “connected to each other by a chain-like alkylene chain that may contain an oxygen atom” means that the (meth) acrylic monomer contains two or more unsaturated bonds, and , Meaning that no cyclic structure is included between the two or more unsaturated bonds. The reason why the curable resin composition of the present invention employs such a (meth) acrylic monomer is that a polyfunctional (meth) acrylic containing a cyclic structure such as a C6 or higher aromatic ring or a C6 or higher aliphatic ring in the molecule. This is because it has been found that crack resistance decreases when a monomer is used.

  The reason why the (meth) acrylic monomer used in the curable resin composition of the present invention has “two or more ethylenically unsaturated bonds” is that the (meth) acrylic monomer contains only one unsaturated bond. This is because the aspect ratio of the cured product is lowered and the resolution of the resin pattern is lowered. The number of unsaturated bonds contained in the (meth) acrylic monomer is preferably 3 or more, and more preferably 3-6. It is preferable that the number of unsaturated bonds contained in the (meth) acrylic monomer is 3 or more because sufficient resolution can be obtained. Moreover, it is preferable at the point which can suppress the time-dependent polymerization of a monomer by the number of unsaturated bonds contained in a (meth) acryl monomer being 6 or less.

  The Tg of the (meth) acrylic monomer is preferably 75 ° C. or higher. When the Tg of the (meth) acrylic monomer is 75 ° C. or higher, it is preferable in that the aspect ratio of the cured product can be increased and the resolution of the resin pattern can be improved. Here, the Tg of the (meth) acrylic monomer means the glass transition temperature (Tg) of the homopolymer when the homopolymer is produced by polymerizing the (meth) acrylic monomer.

  Among the above (meth) acrylic monomers, the (meth) acrylic monomer in the curable resin composition of the present invention is preferably a compound represented by the following general formulas (1) to (3).

（上記一般式（１）中、Ｌは、それぞれ独立に−ＣＨ_２ＣＨ_３又は−ＣＨ_２ＯＨであり、Ｍは、それぞれ独立に−ＣＨ_２Ｏ（Ｃ＝Ｏ）ＣＨ＝ＣＨ_２又は−ＣＨ_２ＯＣ（＝Ｏ）Ｃ（ＣＨ_３）＝ＣＨ_２である。また、ｍは０から２の整数であり、ｎは１から３の整数であり、ｍ＋ｎ＝３である。）

(In the above general formula (1), L is independently —CH ₂ CH ₃ or —CH ₂ OH, and M is independently —CH ₂ O (C═O) CH═CH ₂ or —CH. ₂ OC (= O) C (CH ₃ ) = CH _2. m is an integer from 0 to 2, n is an integer from 1 to 3, and m + n = 3.

（上記一般式（２）中、Ｘは、それぞれ独立に−ＣＨ_２ＣＨ_３又は−ＣＨ_２ＯＨであり、
Ｙは、それぞれ独立に−ＣＨ_２Ｏ（Ｃ＝Ｏ）ＣＨ＝ＣＨ_２、−ＣＨ_２ＯＣ（＝Ｏ）Ｃ（ＣＨ_３）＝ＣＨ_２、−ＣＨ_２Ｏ（Ｃ_２Ｈ_４Ｏ）_ｒＣ（＝Ｏ）ＣＨ＝ＣＨ_２又は−ＣＨ_２Ｏ（Ｃ_３Ｈ_６Ｏ）_ｓ（Ｃ＝Ｏ）ＣＨ＝ＣＨ_２である。また、ｐは０から２の整数であり、ｑは２から４の整数であり、ｐ＋ｑ＝４である。また、ｒ及びｓは、それぞれ１から１５の整数である。）

(In the general formula (2), each X is independently —CH ₂ CH ₃ or —CH ₂ OH,
Y is independently —CH ₂ O (C═O) CH═CH ₂ , —CH ₂ OC (═O) C (CH ₃ ) ═CH ₂ , —CH ₂ O (C ₂ H ₄ O) _r C (═O) CH═CH ₂ or —CH ₂ O (C ₃ H ₆ O) _s (C═O) CH═CH ₂ . P is an integer from 0 to 2, q is an integer from 2 to 4, and p + q = 4. R and s are integers from 1 to 15, respectively. )

（上記一般式（３）中、Ｚは、−Ｃ（＝Ｏ）ＣＨ＝ＣＨ_２、−Ｃ（＝Ｏ）Ｃ（ＣＨ_３）＝ＣＨ_２であり、Ｚ’は、−ＯＣ（＝Ｏ）ＣＨ＝ＣＨ_２又は−Ｏ（Ｃ＝Ｏ）Ｃ（ＣＨ_３）＝ＣＨ_２であり、Ｒは、−（ＯＣ_２Ｈ_４）_ｔ−、−（ＯＣ_３Ｈ_６）_ｕ−、又は−（ＯＣ_２Ｈ_４）_ｖ−（ＯＣ_３Ｈ_６）_ｗ−である。また、ｔ及びｕは、それぞれ１から１５の整数であり、ｖ及びｗは、それぞれ正の整数であり、ｖ及びｗの和が１５以下である。）

(In the general formula (3), Z is —C (═O) CH═CH ₂ , —C (═O) C (CH ₃ ) ═CH ₂ , and Z ′ is —OC (═O). CH = CH ₂ or —O (C═O) C (CH ₃ ) ═CH ₂ , and R is — (OC ₂ H ₄ ) _t —, — (OC ₃ H ₆ ) _u —, or — (OC ₂ H ₄ ) _v- (OC ₃ H ₆ ) _w- , where t and u are each an integer from 1 to 15, v and w are each a positive integer, and the sum of v and w Is 15 or less.)

  Examples of the (meth) acrylic monomer represented by the general formula (1) include dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth). ) Acrylate, dipentaerythritol hexa (meth) acrylate, dimethylolpropane tetra (meth) acrylate and the like. The (meth) acrylic monomer represented by the general formula (2) includes trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, and propylene oxide-modified trimethylolpropane tri (meth) acrylate. And ethylene oxide and propylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and the like. Examples of the (meth) acrylic monomer represented by the general formula (3) include polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, poly (ethylene-propylene) glycol di (meth) acrylate, and the like. The

  Among the (meth) acrylic monomers, dipentaerythritol hexaacrylate, dimethylolpropane tetraacrylate, trimethylolpropane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and polypropylene glycol diacrylate are preferably used.

  3-15 mass% is preferable and, as for content of the (meth) acryl monomer in curable resin composition, it is more preferable that it is 5-12 mass%. If the content of the (meth) acrylic monomer in the curable resin composition is 3% by mass or more, the occurrence of cracks in the cured product obtained by curing the curable resin composition is preferably suppressed. If the content of the (meth) acrylic monomer in the curable resin composition is 15% by mass or less, the aspect ratio of the cured product obtained by curing the curable resin composition is increased, and the pattern resolution is improved. It is preferable at the point which can do. In addition, the said content is a thing when the curable resin composition does not contain the solvent component mentioned later. Therefore, when the curable resin composition contains a solvent component to be described later, the content of the (meth) acrylic monomer after removing the mass of the solvent component may be within the above range.

[Other ingredients]
Other monomers, sensitizers, solvents and the like can be added to the curable resin composition of the present invention depending on the required properties. Hereinafter, these components will be described.

  Examples of the other monomer include a polymer linear bifunctional epoxy resin that is added to improve film formability. Such a polymer linear bifunctional epoxy resin is represented by the following general formula (6).

（上記一般式（７）中、Ｒ^１１〜Ｒ^１４は、水素原子又はメチル基であり、ｙは、正の整数である。）

(In the general formula (7), R ^{11 to} R ¹⁴ are a hydrogen atom or a methyl group, and y is a positive integer.)

  Although it does not specifically limit as said polymeric linear bifunctional epoxy resin, What polymerized bisphenol A type epoxy or bisphenol F type epoxy is illustrated. Moreover, as for the said high molecular linear bifunctional epoxy resin, mass average molecular weight 1000-7000 are preferable, and mass average molecular weight 1000-5000 are more preferable. If the mass average molecular weight of the polymer linear bifunctional epoxy resin is 1000 or more, the film formability is improved, which is preferable. Moreover, it is preferable if the mass average molecular weight of the polymer linear bifunctional epoxy resin is 7000 or less because good compatibility with the polyfunctional epoxy can be obtained. Among these, bisphenol A type epoxy resin (for example, “Epicoat 1004” manufactured by Japan Epoxy Resin Co., Ltd., mass average molecular weight 1650) and bisphenol A novolak type epoxy resin (for example, “jER1007” manufactured by Japan Epoxy Resin Co., Ltd.) , Mass average molecular weight 2900) is particularly preferably used.

  Examples of the sensitizer include naphthol type sensitizers. When the sensitivity of the curable resin composition is high, if there is a gap between the photomask and the film of the curable resin composition, the dimension of the resin pattern (cured product) obtained as a result of exposure will be that of the photomask. In some cases, a phenomenon of becoming thicker than the size may occur. However, this fatening phenomenon can be suppressed without lowering the sensitivity by including a naphthol type sensitizer. Thus, it is preferable to add a naphthol type sensitizer because an error in the dimension of the resin pattern with respect to the dimension of the photomask can be suppressed.

  As such a naphthol type sensitizer, 1-naphthol, β-naphthol, α-naphthol methyl ether, and α-naphthol ethyl ether are preferably exemplified, and the effect of suppressing the resin pattern thickening phenomenon without lowering the sensitivity. Considering this point, 1-naphthol is more preferably exemplified.

  The solvent increases the sensitivity of the curable resin composition, and the viscosity of the curable resin composition is suitable for applying the curable resin composition to the surface of the substrate on which the resin pattern is formed. Used for. Examples of such a solvent include propylene glycol monomethyl ether acetate (PGMEA), methyl isobutyl ketone (MIBK), butyl acetate, methyl amyl ketone (2-heptanone), ethyl acetate, methyl ethyl ketone (MEK) and the like. What is necessary is just to determine the addition amount of the solvent in curable resin composition suitably considering the applicability | paintability of curable resin composition. In the case of the curable resin composition according to the present invention, from the viewpoint of performing pattern formation with an aspect ratio of 1 or more, the solid content concentration of the composition is generally 50 to 80% by mass. Preferably, it is 65-75 mass%.

  In addition, the description about content of each component in this specification was made into the numerical value in the case where a solvent component is not included when there is no note in particular.

  The curable resin composition of the present invention may further contain, if desired, additives that are miscible with the curable resin composition, for example, additional resins, plasticizers, stabilizers, and coloring for improving the performance of the resin pattern. Conventional agents such as agents and surfactants can be appropriately added.

  The usage mode of the curable resin composition of the present invention is not particularly limited. As an example, after applying a solution of the curable resin composition to the surface of the substrate using a spin coater or the like, the solvent is evaporated and removed to form a resin film, and active energy rays are passed through the resin film through a photomask. The method of irradiating and hardening is mentioned. In addition, a method is also possible in which a curable resin composition is formed into a film with both sides protected by a resin film, and this is applied to the surface of a substrate, and then cured by irradiation with active energy rays through a photomask. It is done.

  The curable resin composition exposed based on the pattern of the photomask is subjected to a development process to remove a portion that has not been irradiated with active energy rays, that is, an uncured portion. Thereby, the hardened | cured material as a resin pattern is obtained. The resin pattern may be subjected to post-baking treatment as necessary.

  As described above, the cured product formed by curing the curable resin composition of the present invention has a high aspect ratio and high resolution, and the occurrence of cracks is suppressed. Therefore, in addition to being excellent as an etching mask for etching a substrate, it can be used as a fine resin molded product having excellent dimensional stability necessary for producing an electronic device such as a print head in an ink jet printer.

  Hereinafter, the curable resin composition of the present invention will be described more specifically with reference to examples. However, these examples are only examples for suitably explaining the present invention, and the present invention is not limited at all. Not what you want.

[Photosensitive resin composition (Examples 1 to 10 and Comparative Examples 1 to 7)]
The polyfunctional epoxy resin, the acrylic monomer, the cationic polymerization initiator, and the solvent were mixed according to the formulation shown in Table 1 (unit is part by mass) to prepare curable resin compositions of Examples 1 to 10. Moreover, according to the prescription (a unit is a mass part) of Table 2, a polyfunctional epoxy resin, an acrylic monomer, a cationic polymerization initiator, a radical polymerization initiator, and a solvent are mixed, and the curable resin composition of Comparative Examples 1-7 A product was prepared. In Tables 1 and 2, the polyfunctional epoxy resin is described as “epoxy resin”.

  In Table 1 and Table 2, the epoxy resin A is an 8-functional bisphenol A novolak type epoxy resin (jER157S70 manufactured by Japan Epoxy Resin Co., Ltd.), and the epoxy resin B is an average 5.6 functional bisphenol A novolak type epoxy resin (DIC stock). Epoxy N-865), epoxy resin C is an average bifunctional bisphenol A novolac type epoxy resin (jER1007 manufactured by Japan Epoxy Resin Co., Ltd.), and epoxy resin D is an average bifunctional flexible skeleton type epoxy resin (DIC). Represented by Co., Ltd., Epicron EXA 4850-150).

  Moreover, in Table 1 and Table 2, the acrylic monomer A is dipentaerythritol hexaacrylate (hexafunctional (the number of unsaturated bonds in one molecule is expressed as the functional number. The same shall apply hereinafter), manufactured by Nippon Kayaku Co., Ltd.). The acrylic monomer B is pentaerythritol tetraacrylate (tetrafunctional, manufactured by Toagosei Co., Ltd., Aronix M-450), and the acrylic monomer C is dimethylolpropane tetraacrylate (tetrafunctional, manufactured by Toagosei Co., Ltd., Aronix M-). 408), acrylic monomer D is ethylene oxide-modified trimethylolpropane triacrylate (trifunctional, manufactured by Toagosei Co., Ltd., Aronix M-350), acrylic monomer E is trimethylolpropane triacrylate (trifunctional, Toagosei Co., Ltd.) Made by company, Aronix M-309 Acrylic monomer F is polypropylene glycol diacrylate (bifunctional, manufactured by Toagosei Co., Ltd., Aronix M-270), and acrylic monomer G is tricyclodecane dimethylol diacrylate (trifunctional, manufactured by Toagosei Co., Ltd.) Aronix M-203), acrylic monomer H is 2,2-bis [4- (methacryloxydiethoxy) phenyl] propane (EO addition amount 4 per molecule) (bifunctional, Shin-Nakamura Chemical Co., Ltd., BPE -200), acrylic monomer I is 2,2-bis [4- (methacryloxydiethoxy) phenyl] propane (EO addition amount 30 per molecule) (bifunctional, Shin-Nakamura Chemical Co., Ltd., BPE-1300N) ) Respectively. Among these acrylic monomers, the acrylic monomers G, H, and I have a cyclic structure in the molecule, and the other acrylic monomers do not have a cyclic structure in the molecule and are composed of a chain structure. .

  In Tables 1 and 2, the cationic polymerization initiator A is 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluoroantimonate (manufactured by ADEKA Corporation, SP- 172), cationic polymerization initiator B is diphenyl [4- (phenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate (Sanpro Corporation, CPI-210S), and cationic polymerization initiator C is diphenyl [ 4- (p-terphenylthio) phenyl] sulfonium trifluorotrispentafluoroethyl phosphate (manufactured by San Apro Co., Ltd., HS-1PG) is represented.

  In Tables 1 and 2, Solvent A represents propylene glycol monomethyl ether acetate (PGMEA), and Solvent B represents γ-butyrolactone. Further, in Table 2, radical polymerization initiator A represents Irgacure 907 manufactured by Ciba Specialty Chemicals, and radical polymerization initiator B represents CGI-242 manufactured by Ciba Specialty Chemicals.

[Curing test]
About each of curable resin composition of Examples 1-10 and Comparative Examples 1-7, the curable resin composition was apply | coated on the silicon substrate with the spin coater, and also the solvent contained in the apply | coated curable resin composition Was removed by evaporation to produce a resin film having a thickness of 30 μm on the silicon substrate. As a pre-baking process, after heating this curable resin composition together with a silicon substrate at 90 ° C. for 10 minutes, a photomask provided with a plurality of squares each having a side length of 20 μm as a light-shielding portion is formed by the soft contact. And then irradiated with ultraviolet rays. As a result, the other part of the film is cured by being irradiated with ultraviolet rays while leaving a square part having a side length of 20 μm. For UV irradiation, PLA-501F manufactured by Canon Inc. was used, and 300 mJ / cm ² of ultraviolet light (ghi line) was irradiated.

  After the ultraviolet irradiation, as a post-exposure heating step (PEB), the resin film was heated together with the silicon substrate at 90 ° C. for 5 minutes, and then immersed in PGMEA for 3 minutes as a development step. Through the above steps, a resin pattern having a plurality of square holes was formed on the silicon substrate.

  The obtained resin pattern was observed with a microscope, and the resolution and the presence or absence of cracks were examined. The results are shown in Tables 1 and 2. In the evaluation of cracks in Tables 1 and 2, “◯” means that no crack was observed in the produced resin pattern (cured product), and “x” means that it was produced. This means that cracks were observed in the resin pattern (cured product).

As shown in Table 1, each of the curable resin compositions of Examples 1 to 10 satisfying the predetermined conditions of the present invention showed a resolution of less than 10 μm in the resin pattern as the cured product, and cracks were observed. There was no occurrence.
On the other hand, as shown in Table 2, Comparative Examples 1 and 2, which do not contain an acrylic monomer, Comparative Examples 3 and 4, which do not contain a cationic polymerization initiator and contain a radical polymerization initiator instead, and have a cyclic structure It is understood that in the curable resin compositions of Comparative Examples 5 to 7 containing the acrylic monomer, the resolution or crack resistance is poor in the resin pattern that is the cured product.
From this, it is understood that the curable resin composition satisfying the predetermined condition of the present invention can achieve both good resolution and crack resistance in the cured product.
In addition, in the curable resin composition of Comparative Examples 5 to 7 containing an acrylic monomer having a cyclic structure, Comparative Examples 5 and 6 are cured products with poor crack resistance but good resolution. In Comparative Example 7, the cured product had good crack resistance, but had poor resolution. In the curable resin composition using the acrylic monomer having a cyclic structure, the reason for such a different tendency is presumed as follows. That is, the acrylic monomer used in the curable resin compositions of Comparative Examples 5 and 6 has no ethylene oxide chain or only a short ethylene oxide chain, whereas it is used in the curable resin composition of Comparative Example 7. Acrylic monomers have long ethylene oxide chains. For this reason, in the curable resin composition of Comparative Example 7, it is considered that the obtained cured product was somewhat flexible and the internal stress was reduced. From this, it is understood that when an acrylic monomer having a cyclic structure in the molecule is used, basically, the crack resistance tends to be lowered.

  In addition, among the curable resin compositions of Examples 1 to 10, the curable resin composition of Example 6 using an acrylic monomer having two functional groups (the number of unsaturated bonds) has 3 functional groups. It is understood that the resolution is slightly reduced in the cured product as compared with the curable resin compositions of Examples 1 to 5 and 7 to 10 using the acrylic monomer as described above. From this, it is understood that the acrylic monomer used for the curable resin composition is more preferable if the number of functional groups is 3 or more.

Claims (4)

(A) A curable resin composition containing a polyfunctional epoxy resin that is solid at room temperature, (B) a cationic polymerization initiator, (C) a (meth) acryl monomer, and a solvent,
(A) The polyfunctional epoxy resin that is solid at room temperature is a resin having three or more epoxy groups in one molecule;
The (C) (meth) acrylic monomer has two or more ethylenically unsaturated bonds connected to each other by a chain-like alkylene chain which may contain an oxygen atom;
(A) The content of the polyfunctional epoxy resin solid at normal temperature is 70 to 95% by mass with respect to the total of components other than the solvent, and the content of the (B) cationic polymerization initiator is other than the solvent. The content of the (C) (meth) acrylic monomer is 3 to 15% by mass with respect to the total of components other than the solvent. A curable resin composition. The curable resin composition according to claim 1, wherein the (C) (meth) acrylic monomer is represented by the following general formula (1), general formula (2), or general formula (3).

(In the above general formula (1), L is independently —CH ₂ CH ₃ or —CH ₂ OH, and M is independently —CH ₂ O (C═O) CH═CH ₂ or —CH. ₂ OC (= O) C (CH ₃ ) = CH _2. m is an integer from 0 to 2, n is an integer from 1 to 3, and m + n = 3.

(In the general formula (2), each X is independently —CH ₂ CH ₃ or —CH ₂ OH,
Y is independently —CH ₂ O (C═O) CH═CH ₂ , —CH ₂ OC (═O) C (CH ₃ ) ═CH ₂ , —CH ₂ O (C ₂ H ₄ O) _r C (═O) CH═CH ₂ or —CH ₂ O (C ₃ H ₆ O) _s (C═O) CH═CH ₂ . P is an integer from 0 to 2, q is an integer from 2 to 4, and p + q = 4. R and s are integers from 1 to 15, respectively. )

(In the general formula (3), Z is —C (═O) CH═CH ₂ , —C (═O) C (CH ₃ ) ═CH ₂ , and Z ′ is —OC (═O). CH = CH ₂ or —O (C═O) C (CH ₃ ) ═CH ₂ , and R is — (OC ₂ H ₄ ) _t —, — (OC ₃ H ₆ ) _u —, or — (OC ₂ H ₄ ) _v- (OC ₃ H ₆ ) _w- , where t and u are each an integer from 1 to 15, v and w are each a positive integer, and the sum of v and w Is 15 or less.)   The curable resin composition according to claim 1 or 2, wherein the (C) (meth) acrylic monomer has three or more ethylenically unsaturated groups connected to each other by a chain-like alkylene chain which may contain an oxygen atom.   Hardened | cured material formed by hardening | curing curable resin composition of any one of Claim 1 to 3.