JP5486594B2 - Photosensitive resin composition - Google Patents

Description

  The present invention relates to a photosensitive resin composition that can be developed with an alkaline aqueous solution, and a dry film resist using the composition. More specifically, the present invention uses a photosensitive resin composition suitable for ITO electrode formation and iron alloy etching (chemical milling) in the production of flat panel display display materials and the like, and the composition. It relates to dry film resist.

  Conventionally, printed wiring plates, precision metal processing, and the like are manufactured by a photolithography method. The photolithographic method is a method in which a photosensitive resin composition is applied onto a substrate, pattern exposure is performed to polymerize and cure the exposed portion of the photosensitive resin composition, and an unexposed portion is removed with a developer to form a resist on the substrate. A method of forming a conductor pattern on a substrate by forming a pattern, forming a conductor pattern by etching or plating, and then peeling and removing the resist pattern from the substrate.

  In the photolithography method described above, in applying the photosensitive resin composition onto the substrate, a method of applying a photoresist solution to the substrate and drying, or a support, a layer made of the photosensitive resin composition (hereinafter, “ And a method of laminating a photosensitive resin laminate (hereinafter referred to as “dry film resist”) in which a protective layer is sequentially laminated on a substrate. In the production of printed wiring boards, the latter dry film resist is often used.

Hereinafter, a method for producing a printed wiring board using a dry film resist will be briefly described.
First, a protective layer such as a polyethylene film is peeled off from the dry film resist. Next, the photosensitive resin layer and the support are laminated on a substrate such as a copper-clad laminate using a laminator so that the substrate, the photosensitive resin layer, and the support are in this order. Next, the exposed portion is polymerized and cured by exposing the photosensitive resin layer through a photomask having a wiring pattern. Next, the support made of polyethylene terephthalate or the like is peeled off. Next, a non-exposed portion of the photosensitive resin layer is dissolved or dispersed and removed by a developing solution such as an aqueous solution having weak alkalinity to form a resist pattern on the substrate. Next, a known etching process or pattern plating process is performed using the formed resist pattern as a protective mask. Finally, the resist pattern is peeled from the substrate to produce a substrate having a conductor pattern, that is, a printed wiring board.

On the other hand, display materials such as various flat panel displays have been actively developed in recent years, and their uses are expanding in the future. As an example of this display material, there is an ITO electrode formed on a glass or polyethylene terephthalate substrate, and the above-mentioned dry film resist is being used for forming the electrode by etching.
However, conventional dry film resists have poor adhesion because the substrate is a smooth ITO film, SnO ₂ film, etc., unlike the general metals such as copper, in the above electrode formation. Furthermore, since it is exposed to strong acid during etching, there is a problem that the resist is peeled off from the base material, side etching proceeds, and high-precision etching cannot be performed. In order to overcome this, an adhesion assistant such as a silane coupling agent has been introduced.

Patent Document 1 below discloses that the adhesiveness of the photosensitive resin composition to the ITO film is improved by including 0.01 to 0.5 parts by mass of a silane coupling agent. However, since the adhesion assistant itself is unstable, it cannot be said that the point that the storage stability of the photosensitive resin composition tends to deteriorate is sufficiently solved.
Patent Document 2 below describes a photosensitive resin composition containing 0.001 to 5 parts by mass of a polyfunctional thiol compound having two or more mercapto groups in one molecule. In addition, only an effect as an adhesion aid for a copper base material is disclosed, and there is no disclosure about an effect of improving adhesion to an ITO film or storage stability.

Japanese Patent Laid-Open No. 10-198032 JP 58-1000084

  The problem to be solved by the present invention is to provide a photosensitive resin composition excellent in chemical resistance, adhesion to an ITO film and excellent in storage stability, and a photosensitive resin laminate using the same. That is.

The inventors of the present application have made extensive studies to solve the above-mentioned problems, and, as a result of repeated experiments, have found that the above-described problems can be unexpectedly solved with the following configuration, and have completed the present invention.
That is, the present invention is as follows.

  [1] (A) Alkali-soluble resin 40 to 90% by mass, (B) 5 to 50% by mass of a compound having an ethylenically unsaturated double bond, (C) 1 to 20% by mass of a photopolymerization initiator, (D) The photosensitive resin composition containing 0.001-2.5 mass% of epoxy silane compounds and 0.005-1.0 mass% of (E) thiol compounds.

｛式中、Ｒ_１は芳香族性を有する基である。｝で表されるチオール化合物である、請求項１に記載の感光性樹脂組成物。
［３］前記（Ｅ）一般式（Ｉ）で表されるチオール化合物が、該式中、Ｒ_１が芳香族性を有する複素環化合物である、前記［２］に記載の感光性樹脂組成物。[2] The (E) thiol compound is represented by the following general formula (I):

{In the formula, R ₁ is a group having aromaticity. } The photosensitive resin composition of Claim 1 which is a thiol compound represented by these.
[3] The photosensitive resin composition according to [2], wherein the (E) thiol compound represented by the general formula (I) is a heterocyclic compound in which R ₁ has aromaticity. .

｛式中、Ｒ_２は、ＳＨ、ＳＲ_３ＯＲ_４及びＮＲ_３Ｒ_４からなる群から選ばれる一種の基であり、Ｒ_３及びＲ_４は、それぞれ独立に、Ｈ、炭素数１〜１２のアルキル基、及びアリール基からなる群から選ばれる一種の基である。｝で表される化合物である、前記［２］に記載の感光性樹脂組成物。[4] (E) The thiol compound represented by the general formula (I) is represented by the following general formula (II):

{In the formula, R ₂ is a kind of group selected from the group consisting of SH, SR ₃ OR ₄ and NR ₃ R ₄ , and R ₃ and R ₄ are independently H, C 1-12. It is a kind of group selected from the group consisting of an alkyl group and an aryl group. } The photosensitive resin composition as described in said [2] which is a compound represented by these.

｛式中、Ｒ_５は、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のアルキルチオ基、ＳＨ、及びＮＲ_６Ｒ_７からなる群から選ばれる一種の基であり、Ｒ_６及びＲ_７は、それぞれ独立に、Ｈ、炭素数１〜１２のアルキル基、及びアリール基からなる群から選ばれる一種の基である。｝で表される化合物である、前記［２］に記載の感光性樹脂組成物。[5] The thiol compound (E) is represented by the following general formula (III):

{In the formula, R ₅ is a kind selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkylthio group having 1 to 3 carbon atoms, SH, and NR ₆ R ₇ . Each of R ₆ and R ₇ is independently a group selected from the group consisting of H, an alkyl group having 1 to 12 carbon atoms, and an aryl group. } The photosensitive resin composition as described in said [2] which is a compound represented by these.

｛式中、Ｒ_８は、炭素数１〜５のアルキル基であり、Ａは、炭素数１〜４のアルキル基又は−（Ｄ−Ｏ）_ｎ−であり、Ｄは、炭素数１〜３のアルキル基であり、ｎは、１〜５の整数であり、Ｂは下記一般式（Ｖ）：

で表される官能基を有する基である。｝で表される化合物である、前記［１］〜［５］のいずれかに記載の感光性樹脂組成物。[6] The (D) epoxysilane compound is represented by the following general formula (IV):

{In the formula, R ₈ is an alkyl group having 1 to 5 carbon atoms, A is an alkyl group having 1 to 4 carbon atoms or-(DO) _n- , and D is an alkyl group having 1 to 3 carbon atoms. N is an integer of 1 to 5, and B is the following general formula (V):

It is group which has the functional group represented by these. } The photosensitive resin composition in any one of said [1]-[5] which is a compound represented by these.

  [7] The above [1] to [6], wherein the mass ratio of the (A) alkali-soluble polymer to the (B) compound having an ethylenically unsaturated double bond is 1.5 to 1.8: 1. The photosensitive resin composition in any one of 1.

  [8] A photosensitive resin laminate in which a photosensitive resin layer made of the photosensitive resin composition according to any one of [1] to [7] is laminated on a support film.

  [9] Includes a laminating step of laminating the photosensitive resin laminate according to [8] on a transparent electrode, an exposure step of exposing the laminate, and a developing step of developing the exposed laminate. A resist pattern forming method.

[10] A method for manufacturing an electrode, comprising etching the transparent electrode according to a resist pattern obtained by the pattern forming method according to [9].
[11] A laminating step of laminating the photosensitive resin laminate according to [8] on an iron-based alloy, an exposure step of exposing the laminate, and a developing step of developing the exposed laminate. And a resist pattern forming method.
[12]
A method for producing an iron-based alloy structure, comprising etching the iron-based alloy according to a resist pattern obtained by the pattern forming method according to [11].

  The present invention provides a photosensitive resin composition having good adhesion to an ITO film and excellent in storage stability, and a photosensitive resin laminate using the same. The photosensitive resin composition of this invention and the photosensitive resin laminated body using the same are excellent in pattern formation, and can be used suitably for the etching use of an ITO film | membrane.

Hereinafter, the present invention will be described in detail.
<(A) Alkali-soluble resin>
The alkali-soluble resin is a vinyl resin containing a carboxyl group, and is, for example, a copolymer such as (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylonitrile, (meth) acrylamide, and the like. .
(A) It is preferable that alkali-soluble resin contains a carboxyl group and an acid equivalent is 100-600. The acid equivalent refers to the mass of the alkali-soluble resin having 1 equivalent of a carboxyl group therein.
The acid equivalent is more preferably 250 or more and 450 or less. The acid equivalent is preferably 100 or more from the viewpoint of improving development resistance and improving resolution and adhesion, and is preferably 600 or less from the viewpoint of improving developability and peelability. The acid equivalent is measured by a potentiometric titration method using Hiranuma automatic titrator (COM-555) manufactured by Hiranuma Sangyo Co., Ltd. and 0.1 mol / L sodium hydroxide.

  (A) It is preferable that the weight average molecular weight of alkali-soluble resin is 20,000 or more and 80,000 or less. The weight average molecular weight of the alkali-soluble resin is preferably 80,000 or less from the viewpoint of improving developability. The properties of the development aggregate, the edge fuse property in the case of the photosensitive resin laminate, the cut chip property, etc. From the viewpoint of properties, it is preferably 20,000 or more. The edge fuse property is a phenomenon in which the photosensitive resin composition layer protrudes from the end surface of the roll when the photosensitive resin laminate is wound into a roll. The cut chip property is the phenomenon that the chip flies when the unexposed film is cut with a cutter. If the chip adheres to the top surface of the photosensitive resin laminate, it is transferred to the mask during the subsequent exposure process, etc. It becomes. The weight average molecular weight of the alkali-soluble resin is more preferably 20,000 or more and 60,000 or less, and further preferably 40,000 or more and 60,000 or less.

The weight average molecular weight was measured by Gel Permeation Chromatography (GPC) manufactured by JASCO Corporation (pump: Gulliver, PU-1580 type, column: Shodex (registered trademark) manufactured by Showa Denko KK (KF-807, KF-806M). , KF-806M, KF-802.5) in series, moving bed solvent: tetrahydrofuran, polystyrene standard sample (use of calibration curve by Shodex STANDARD SM-105 manufactured by Showa Denko KK) as polystyrene conversion.
The alkali-soluble resin can be obtained by copolymerizing one or more monomers from the following two types of monomers.

The first monomer is a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Examples include (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, and maleic acid half ester. Among these, (meth) acrylic acid is particularly preferable. Here, (meth) acryl refers to acryl and / or methacryl. The same applies hereinafter.
The second monomer is a non-acidic monomer having at least one polymerizable unsaturated group in the molecule. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl ( (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, vinyl alcohol esters such as vinyl acetate, (meth) Examples include acrylonitrile, styrene, and styrene derivatives. Among these, methyl (meth) acrylate, n-butyl (meth) acrylate, styrene, and benzyl (meth) acrylate are preferable. Benzyl (meth) acrylate is preferred from the viewpoint of floating the bottom of the resist foot after development.

The copolymerization ratio of the first monomer and the second monomer is preferably 10 to 60% by mass of the first monomer and 40 to 90% by mass of the second monomer. More preferably, the first monomer is 15 to 35% by mass, and the second monomer is 65 to 85% by mass.
Preferred combinations of the first monomer and the second monomer include the following combinations. That is, butyl acrylate, methyl methacrylate, methacrylic acid copolymer, styrene, methyl methacrylate, methacrylic acid copolymer, styrene, benzyl methacrylate, methacrylic acid copolymer, benzyl methacrylate, methacrylic acid Examples include copolymers, benzyl methacrylate, acrylic acid-2-ethylhexyl, and methacrylic acid copolymers.
(A) The compounding quantity of the photosensitive resin composition of alkali-soluble polymer is the range of 40-90 mass% when the total solid content mass of the photosensitive resin composition is 100 mass%, preferably 50-70 mass. %. From the viewpoint of edge fuse property, it is 40% by mass or more, and from the viewpoint of development time, it is 70% by mass or less.

<(B) Compound having an ethylenically unsaturated double bond>
(B) As the compound having an ethylenically unsaturated double bond, at least one terminal ethylenically unsaturated group is a photopolymerizable monomer, and specific examples thereof include polypropylene glycol di (meth) acrylate, polyethylene Glycol (meth) acrylate, 2-di (p-hydroxyphenyl) propane (meth) acrylate, glycerol tri (meth) acrylate trimethylol tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate, polyoxyethyl Trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, trimethylpropanetriglycidyl ether tri (meth) acrylate, vinyl Phenol A-ethylene glycol adducts di (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, nonyl phenoxy polyethylene glycol (meth) acrylate.
Moreover, a urethane compound is also mentioned, for example, there are hexamethylene diisocyanate and tolylene diisocyanate. These may be used alone or in combination of two or more.

  (B) The compounding quantity of the compound which has an ethylenically unsaturated double bond is 5-50 mass% when the total solid content mass is 100 mass% of the photosensitive resin composition. From the viewpoint of sensitivity, resolution, and adhesion, it is 5% by mass or more. On the other hand, it is 60% by mass or less from the viewpoint of suppressing the cold flow and the delayed peeling of the cured resist, and preferably 25 to 45% by mass. is there.

<(C) Photopolymerization initiator>
(C) As the photopolymerization initiator, those generally known can be used. (C) Content of a photoinitiator is the range of 0.1-20 mass%, and a preferable range is 0.5-10 mass%. From the viewpoint of obtaining sufficient sensitivity, it is preferably 0.1% by mass or more. On the other hand, from the viewpoint of sufficiently transmitting light to the bottom of the resist and obtaining good high resolution, it is 20% by mass or less.
As photopolymerization initiators, 2-ethylanthraquinone, octaethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-chloro Anthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone Quinones such as 2,3-dimethylanthraquinone and 3-chloro-2-methylanthraquinone, aromatic ketones such as benzophenone, Michler's ketone 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis ( Diethylamino) benzophenone, ben In or benzoin ethers, benzoin, benzoin ethyl ether, benzoin phenyl ether, methyl benzoin, ethyl benzoin, dialkyl ketals, benzyl dimethyl ketal, benzyl diethyl ketal, thioxanthones, diethyl thioxanthone, chlorothioxanthone, dialkylaminobenzoates, Ethyl dimethylaminobenzoate, oxime esters, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) oxime, 2 -(O-chlorophenyl) -4,5-diphenylimidazolyl dimer, 2- (o-chlorophenyl) -4,5-bis- (m-methoxyphenyl) imidazolyl dimer, 2- (p-meth) Xylphenyl) -4,5-diphenylimidazolyl dimer, acridine compound, 9-phenylacridine, pyrazolines, 1-phenyl-3-styryl-5-phenyl-pyrazoline, 1- (4-tert-butyl-phenyl)- Examples include 3-styryl-5-phenyl-pyrazolin, 1-phenyl-3- (4-tert-butyl-styryl) -5- (4-tert-butyl-phenyl) -pyrazoline, and the like. These compounds may be used alone or in combination of two or more.

  A combination of the above-mentioned lophine dimer and Michler's ketone 4,4′-bis (dimethylamino) benzophenone or 4,4′-bis (diethylamino) benzophenone is a preferable combination from the viewpoints of sensitivity and resolution. In this case, the amount of the lophine dimer can be appropriately adjusted according to the sensitivity and the development aggregation property. When 2- (o-chlorophenyl) -4,5-diphenylimidazolyl dimer is used, it is preferably 1% by mass or more from the viewpoint of sensitivity, and preferably 5% by mass or less from the viewpoint of aggregation. More preferably, it is 2-4 mass%. The amount of 4,4′-bis (diethylamino) benzophenone can be appropriately adjusted in consideration of sensitivity, rectangularity of the resist pattern, and light transmittance at the exposure wavelength. In the case of forming a photosensitive resin layer having a thickness of 70 μm or more, it is preferably 0.05% by mass or less in consideration of pattern adhesion and rectangularity. From the viewpoint of sensitivity, 0.01% by mass or more is preferable.

｛式中、Ｒ_８は、炭素数１〜５のアルキル基であり、Ａは、炭素数１〜４のアルキル基又は−（Ｄ−Ｏ）_ｎ−であり、Ｄは、炭素数１〜３のアルキル基であり、ｎは、１〜５の整数であり、Ｂは下記一般式（Ｖ）：

で表される官能基を有する基である。｝で表される化合物であることが好ましい。<(D) Epoxysilane compound>
(D) An epoxy silane compound is an organosilicon compound having both an epoxy group reactively bonded to an organic material and a hydrolyzable alkoxy group reactively bonded to an inorganic material in the molecule, and from the viewpoint of adhesion, The following general formula (IV):

{In the formula, R ₈ is an alkyl group having 1 to 5 carbon atoms, A is an alkyl group having 1 to 4 carbon atoms or-(DO) _n- , and D is an alkyl group having 1 to 3 carbon atoms. N is an integer of 1 to 5, and B is the following general formula (V):

It is group which has the functional group represented by these. } Is preferable.

  Specific examples include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxymethyltrimethoxysilane, 3-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxy. Silane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropyltripentoxysilane, 3-glycidylmethyltrimethoxysilane Examples include 3-glycidylethyltrimethoxysilane, 3-glycidylpropyltrimethoxysilane, and the like. (D) Among the above-mentioned epoxy silane compounds, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane are adhesive. From the viewpoint of (D) The compounding quantity of an epoxy silane compound is 0.001-2.5 mass% when the total solid content mass is 100 mass% of the photosensitive resin composition. From the viewpoint of adhesion, it is 0.001% by mass or more, and from the viewpoint of storage stability, it is 2.5% by mass or less. (D) The compounding quantity of an epoxysilane compound becomes like this. Preferably it is 0.03-0.3 mass%, More preferably, it is 0.05-0.15 mass%.

｛式中、Ｒ_１は芳香族性を有する基である。｝で表されるチオール化合物が挙げられる。
上記芳香族性を有する基としては、例えば、フェニル基、ナフチル基、アントラセニル基、イミダゾイル基、トリアゾイル基、テトラゾイル基、ベンゾイミダゾイル基、ベンゾトリアゾイル基、ベンゾテトラゾイル基、オキサゾイル基、ベンゾオキサゾイル基、チアゾイル基、ベンゾチアゾイル基、チアジアゾイル基、トリアジン基、ピリジル基、ピロリル基、フリル基、チエニル基、キノリル基が挙げられる。<(E) Thiol compound represented by the following general formula (I)>
The photosensitive resin composition included in the present invention contains 0.005 to 1.0% by mass of (E) thiol compound, and this can be expected to improve the storage stability. In the present application, the storage stability means that there is no change with time in the contrast when the photosensitive resin laminate is exposed.
(E) As a thiol compound, the compound which the mercapto group couple | bonded with the carbon atom which does not have aromaticity, and the compound which the mercapto group couple | bonded with the group which has aromaticity can be mentioned.
Examples of the compound in which a mercapto group is bonded to a carbon atom having no aromaticity include, for example, octanethiol, hexanedithiol, decanedithiol, 1,4-butanediol bisthiopropionate, and 1,4-butanediol bisthioglyco. Rate, ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, trimethylolpropane, tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tris (3-mercaptobutyrate), pentaerythritol tetrakis Thioglycolate, pentaerythritol tetrakisthiopropionate, trimercaptopropionate tris, (2-hydroxyethyl) isocyanurate, pentaerythritol tetrakis-3 It can be mentioned mercaptobutylate.
Examples of the compound in which a mercapto group is bonded to an aromatic group include the following general formula (I):

{In the formula, R ₁ is a group having aromaticity. } The thiol compound represented by this is mentioned.
Examples of the aromatic group include a phenyl group, a naphthyl group, an anthracenyl group, an imidazolyl group, a triazoyl group, a tetrazoyl group, a benzoimidazoloyl group, a benzotriazoyl group, a benzotetrazoyl group, an oxazoyl group, a benzooxa group. Examples include zoyl group, thiazoyl group, benzothiazoyl group, thiadiazoyl group, triazine group, pyridyl group, pyrrolyl group, furyl group, thienyl group, and quinolyl group.

R ₁ is preferably a heterocyclic compound having aromaticity from the viewpoint of storage stability. In this application, the resolution is a negative for resolution evaluation, using a negative in which the line width of the line and the space width are alternately arranged at an equal width of 10 μm to 50 μm, and the unexposed area is completely swollen and dissolved and removed by development. The one with the smallest width.
Examples of the thiol compound represented by the general formula (I) include 2-chlorothiophenol, 3-chlorothiophenol, 4-chlorothiophenol, 2-aminothiophenol, 3-aminothiophenol, 4-aminothiophenol, 2-bromothiophenol, 3-bromothiophenol, 4-bromothiophenol, 2-fluorothiophenol, 3-fluorothiophenol, 4-fluorothiophenol, 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 2,3-dimethylthiophenol, 2,4-dimethylthiophenol, 2,5-dimethylthiophenol, 2,6-dimethylthiophenol, 2, 3-difluorothiophenol, 2,4-difluorothiophenol, 2,5 -Difluorothiophenol, 2,6-difluorothiophenol, 2,3-dichlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 2,6-dichlorothiophenol, 3,4-dimethoxy Thiophenol, 3-chloro-4-fluorothiophenol, 4-isopropylthiophenol, 3,5- (trifluoromethyl) benzenethiol, 2-mercaptobenzoic acid, 2-amino-4-chlorothiophenol, 4-acetamide Thiophenol, 2-chloro-4-fluorothiophenol, 4-chloro-2,5-dimethylthiophenol, 1,3,5-trimercaptobenzene, 5-bromo-1,3-dimercaptobenzene 2,3 5,6-tetrafluorothiophenol, 2-mercaptopyridine 3-mercaptopyridine, 4-mercaptopyridine, 2-mercaptopyridine-N-oxide, 5-methoxy-2-benzimidazolethiol, 5-amino-2-mercaptobenzimidazole, 2-mercapto-1-methylimidazole, 2- Mercapto-5-methylbenzimidazole, 2-mercapto-5-nitrobenzimidazole, 4-hydroxy-2-mercapto-6- (trifluoromethyl) pyrimidine, 4-mercaptopyrazolo [3,4d] pyrimidine, 4,6 -Diamino-2-mercaptopyrimidine, 4,6-dihydroxy-2-mercaptopyrimidine, 2-mercapto-4,6-dimethylpyrimidine, 5-phenyl-1,3,4-oxadiazole-2-thiol, 4, 5-diphenyl-2-mercaptooxazole, 2- Examples include benzoxazole thiol, 3-phenyl-1,2,4-triazole-5-thiol, 5-mercapto-1-methyltetrazole, 1-phenyl-5-mercapto-1H-tetrazole, and 2-mercaptoimidazoline.

｛式中、Ｒ_２は、ＳＨ、ＳＲ_３ＯＲ_４及びＮＲ_３Ｒ_４からなる群から選ばれる一種の基であり、Ｒ_３及びＲ_４は、それぞれ独立に、Ｈ、炭素数１〜１２のアルキル基、及びアリール基からなる群から選ばれる一種の基である。｝で表される化合物である。The thiol compound represented by the general formula (I) is more preferably the following general formula (II):

{In the formula, R ₂ is a kind of group selected from the group consisting of SH, SR ₃ OR ₄ and NR ₃ R ₄ , and R ₃ and R ₄ are independently H, C 1-12. It is a kind of group selected from the group consisting of an alkyl group and an aryl group. } It is a compound represented.

  Examples of the thiol compound represented by the general formula (II) include 2,4,6-trimercapto-s-triazine, 2-di-n-butylamino-4,6-dimercapto-s-triazine, 2- Anilino-4,6-dimercapto-s-triazine, 6-diallylamino-1,3,5-triazine-2,4-dithiol, 2-dicyclohexylamino-4,6-dimercapto-s-triazine, dimethylamino-1 3,5-triazine-2,4-dithiol.

｛式中、Ｒ_５は、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のアルキルチオ基、ＳＨ、及びＮＲ_６Ｒ_７からなる群から選ばれる一種の基であり、Ｒ_６及びＲ_７は、それぞれ独立に、Ｈ、炭素数１〜１２のアルキル基、及びアリール基からなる群から選ばれる一種の基である。｝で表される化合物も、保存安定性を付与する効果が期待できる。Moreover, as a thiol compound represented by the above general formula (I), the following general formula (III):

{In the formula, R ₅ is a kind selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkylthio group having 1 to 3 carbon atoms, SH, and NR ₆ R ₇ . Each of R ₆ and R ₇ is independently a group selected from the group consisting of H, an alkyl group having 1 to 12 carbon atoms, and an aryl group. }, The effect of imparting storage stability can also be expected.

  Examples of the thiol compound represented by the general formula (III) include 5-methyl-2-mercapto-1,3,4-thiadiazole, 5-ethyl-2-mercapto-1,3,4-thiadiazole, 5 N-propyl-2-mercapto-1,3,4-thiadiazole, 5-isopropyl-2-mercapto-1,3,4-thiadiazole, 5-methoxy-2-mercapto-1,3,4-thiadiazole, 5 -Ethoxy-2-mercapto-1,3,4-thiadiazole, 5-n-propyloxy-2-mercapto-1,3,4-thiadiazole, 5-isopropyloxy-2-mercapto-1,3,4-thiadiazole 5-methylthio-2-mercapto-1,3,4-thiadiazole, 5-ethylthio-2-mercapto-1,3,4-thiadiazole 5-n-propylthio-2-mercapto-1,3,4-thiadiazole, 5-isopropylthio-2-mercapto-1,3,4-thiadiazole, 5-amino-2-mercapto-1,3,4-thiadiazole 2,5-dimercapto-1,3,4-thiadiazole.

In particular, 5-amino-2-mercapto-1,3,4-thiadiazole and 2-di-n-butylamino-4,6-dimercapto-s-triazine are preferable because they have a high effect of maintaining storage stability. . These may be used alone or in combination of two or more.
(E) The compounding quantity of the photosensitive resin composition of the thiol compound represented by the said general formula (I) is 0.005-1.0 mass when the total solid mass of the photosensitive resin composition is 100 mass%. %, Preferably 0.01 to 0.1% by mass, more preferably 0.03 to 0.08% by mass. From the viewpoint of maintaining storage stability, it is 0.005% by mass or more, and from the viewpoint of resolution, it is 1.0% by mass or less.

<Other ingredients>
The photosensitive resin composition according to the present invention may contain a leuco dye, a fluoran dye, or a coloring substance. By including these dyes, the exposed portion is colored, which is preferable in terms of visibility. In addition, the inclusion of these dyes is advantageous when the inspection machine or the like reads the alignment marker for exposure when the contrast between the exposed and unexposed areas is higher.
Examples of the leuco dye include tris (4-dimethylaminophenyl) methane [leucocrystal violet] and bis (4-dimethylaminophenyl) phenylmethane [leucomalachite green]. Among these, from the viewpoint of improving the contrast, it is preferable to use leuco crystal violet as the leuco dye. When the leuco dye is contained, the content of the photosensitive resin composition is preferably 0.1 to 10% by mass. The content is preferably 0.1% by mass or more from the viewpoint of the contrast between the exposed part and the unexposed part, and is preferably 10% by mass or less from the viewpoint of maintaining storage stability.

Moreover, it is a preferable embodiment of this invention from a viewpoint of adhesiveness and contrast to use in combination with a leuco dye and the following halogen compound in the photosensitive resin composition.
Examples of the coloring substance include fuchsin, phthalocyanine green, auramine base, paramadienta, crystal violet, methyl orange, Nile blue 2B, Victoria blue, malachite green (Aizen (registered trademark) MALACHITE GREEN manufactured by Hodogaya Chemical Co., Ltd.), basic blue. 20, Diamond Green (Eizen (registered trademark) DIAMOND GREEN GH manufactured by Hodogaya Chemical Co., Ltd.). It is preferable that the addition amount in the case of containing a coloring substance is 0.001-1 mass% in the photosensitive resin composition. A content of 0.001% by mass or more is preferable from the viewpoint of improving handleability, and a content of 1% by mass or less is preferable from the viewpoint of maintaining storage stability.

  The photosensitive resin composition may contain an N-aryl-α-amino acid compound from the viewpoint of sensitivity. As the N-aryl-α-amino acid compound, N-phenylglycine is preferable. The content when the N-aryl-α-amino acid compound is contained is preferably 0.01% by mass or more and 1% by mass or less.

  The photosensitive resin composition may contain a halogen compound. Examples of the halogen compound include amyl bromide, isoamyl bromide, isobutylene bromide, ethylene bromide, diphenylmethyl bromide, benzyl bromide, methylene bromide, tribromomethylphenyl sulfone, carbon tetrabromide, tris (2 , 3-dibromopropyl) phosphate, trichloroacetamide, amyl iodide, isobutyl iodide, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, chlorinated triazine compounds, among others. Tribromomethylphenylsulfone is preferably used. Content in the case of containing a halogen compound is 0.01-3 mass% in the photosensitive resin composition.

In order to improve the thermal stability and storage stability of the photosensitive resin composition, the photosensitive resin composition is at least one selected from the group consisting of radical polymerization inhibitors, benzotriazoles, and carboxybenzotriazoles. You may further contain a compound more than a seed | species.
Examples of the radical polymerization inhibitor include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, 2,2′-methylenebis. (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), nitrosophenylhydroxyamine aluminum salt, diphenylnitrosamine and the like.

Examples of benzotriazoles include 1,2,3-benzotriazole, 1-chloro-1,2,3-benzotriazole, bis (N-2-ethylhexyl) aminomethylene-1,2,3-benzotriazole, Bis (N-2-ethylhexyl) aminomethylene-1,2,3-tolyltriazole, bis (N-2-hydroxyethyl) aminomethylene-1,2,3-benzotriazole and the like can be mentioned.
Examples of carboxybenzotriazoles include 4-carboxy-1,2,3-benzotriazole, 5-carboxy-1,2,3-benzotriazole, and N- (N, N-di-2-ethylhexyl) aminomethylene. Examples thereof include carboxybenzotriazole, N- (N, N-di-2-hydroxyethyl) aminomethylenecarboxybenzotriazole, N- (N, N-di-2-ethylhexyl) aminoethylenecarboxybenzotriazole and the like.

  The total content of radical polymerization inhibitors, benzotriazoles and carboxybenzotriazoles is preferably 0.01 to 3% by mass, more preferably 0.05 to 1%, based on the entire photosensitive resin composition. % By mass. The content is preferably 0.01% by mass or more from the viewpoint of imparting storage stability to the photosensitive resin composition, and is 3% by mass or less from the viewpoint of maintaining sensitivity and suppressing decolorization of the dye. More preferred.

The photosensitive resin composition may contain a plasticizer as necessary. Examples of such plasticizers include polyethylene glycol, polypropylene glycol, polyoxypropylene polyoxyethylene ether, polyoxyethylene monomethyl ether, polyoxypropylene monomethyl ether, polyoxyethylene polyoxypropylene monomethyl ether, and polyoxyethylene monoethyl. Ether, polyoxypropylene monoethyl ether, glycols and esters such as polyoxyethylene polyoxypropylene monoethyl ether, phthalates such as diethyl phthalate, o-toluenesulfonic acid amide, p-toluenesulfonic acid amide, citric acid Tributyl, triethyl citrate, triethyl acetylcitrate, tri-n-propyl acetylcitrate, tri-n-acetylcitrate Such as chill, and the like.
As content of a plasticizer, it is preferable to contain 5-50 mass% in the photosensitive resin composition, More preferably, it is 5-30 mass%. The content is preferably 5% by mass or more from the viewpoint of suppressing development time delay and imparting flexibility to the cured film, and is preferably 50% by mass or less from the viewpoint of suppressing insufficient curing and cold flow. .

<Photosensitive resin composition preparation solution>
Examples of the solvent that dissolves the photosensitive resin composition include ketones typified by methyl ethyl ketone (MEK), alcohols typified by methanol, ethanol, and isopropanol. It is preferable to add the said solvent to the photosensitive resin composition so that the viscosity of the solution of the photosensitive resin composition apply | coated on a support film may be 500-4,000 mPa * s at 25 degreeC.

<Photosensitive resin laminate>
The photosensitive resin laminate includes a photosensitive resin layer made of a photosensitive resin composition and a support film. If necessary, you may have a protective layer on the surface on the opposite side to the support film side of the photosensitive resin layer. The support film used here is preferably a transparent film that transmits light emitted from the exposure light source. Examples of such support films include polyethylene terephthalate film, polyvinyl alcohol film, polyvinyl chloride film, vinyl chloride copolymer film, polyvinylidene chloride film, vinylidene chloride copolymer film, polymethyl methacrylate copolymer film, Examples include polystyrene film, polyacrylonitrile film, styrene copolymer film, polyamide film, and cellulose derivative film. These films can be stretched if necessary. The haze is preferably 5 or less. The thinner the film, the more advantageous in terms of image formation and economy, but a film having a thickness of 10 to 30 μm is preferably used in order to maintain the strength.

  An important characteristic of the protective layer used in the photosensitive resin laminate is that the protective layer is sufficiently smaller than the support film in terms of adhesion to the photosensitive resin layer and can be easily peeled. For example, a polyethylene film or a polypropylene film can be preferably used as the protective layer. Also, a film having excellent peelability disclosed in JP-A-59-202457 can be used. The thickness of the protective layer is preferably 10 to 100 μm, and more preferably 10 to 50 μm. The thickness of the photosensitive resin layer in the photosensitive resin laminate varies depending on the application, but is preferably 5 to 100 μm, more preferably 7 to 60 μm. The thinner the resolution is, the higher the film strength is. .

A known method can be employed as a method for producing a photosensitive resin laminate by sequentially laminating a support film, a photosensitive resin layer, and, if necessary, a protective layer. For example, the photosensitive resin composition used for the photosensitive resin layer is mixed with a solvent that dissolves them to form a uniform solution, which is first applied onto the support film using a bar coater or a roll coater, and then dried to form the support film. A photosensitive resin layer made of a photosensitive resin composition can be laminated thereon.
The thickness of the photosensitive resin layer after drying is preferably 1 to 100 μm, more preferably 2 to 50 μm, and still more preferably 3 to 15 μm. The thickness is preferably 3 μm or more from the viewpoint of tent properties, and is preferably 15 μm or less from the viewpoint of resolution.
Next, if necessary, a photosensitive resin laminate can be produced by laminating a protective layer on the photosensitive resin layer.

<ITO electrode forming method using the photosensitive resin assembly laminate of the present invention>
Hereinafter, an ITO electrode forming method (pattern formation) using the photosensitive resin laminate of the present invention will be described.
In addition, the photosensitive resin laminated body of this invention can be used suitably for the etching (chemical milling) of an iron-type alloy besides ITO. Examples of iron-based alloys include alloys such as iron-chromium-nickel, 42 alloy, and SUS. The iron-based alloy can be used for a lead frame, an electronic device casing, and the like.
(Base material)
The ITO film is a thin film of indium and tin oxide and is used as a transparent electrode. Usually, a glass substrate or a transparent resin substrate such as polyethylene terephthalate (PET), polyethylene terephthalate (PEN), or polycarbonate (PC) is formed by a method such as sputtering or vapor deposition. The film thickness is generally 20 nm to 300 nm and is appropriately adjusted according to the application. Examples of the compound used as a transparent electrode similar to ITO include IZO and SnO ₂ .

(1) Laminating Step While peeling off the protective layer of the photosensitive resin composition, the photosensitive resin layer of the photosensitive resin laminate is heated and pressure-bonded to the glass substrate surface with a laminator and laminated. The heating temperature at this time is generally 40 to 160 ° C. Moreover, the adhesiveness with respect to the board | substrate of the obtained resist pattern improves by performing this thermocompression bonding twice or more. At this time, a two-stage laminator provided with two rolls may be used for pressure bonding, or it may be repeatedly pressed through the roll several times.

(2) Exposure process The mask film which has a desired wiring pattern is stuck on a support body, and it exposes using an active light source. Examples of the active light source used include a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp. In order to obtain a finer resist pattern, it is more preferable to use a parallel light source. When it is desired to reduce the influence of dust or foreign matter as much as possible, exposure (proximity exposure) may be performed in a state where the photomask is floated by several tens to several hundreds of um from the support.

(3) Development step After the exposure, the support on the photosensitive resin layer is peeled off, and then the unexposed portion is developed and removed using a developer of an alkaline aqueous solution to obtain a resist image. As the alkaline aqueous solution, an aqueous solution of Na ₂ CO ₃ or K ₂ CO ₃ is used. The alkaline aqueous solution is appropriately selected according to the characteristics of the photosensitive resin layer, but a Na ₂ CO ₃ aqueous solution having a concentration of about 0.2 to 2% by mass and about 20 to 40 ° C. is generally used. A surface active agent, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be mixed in the alkaline aqueous solution. An amine-based alkaline aqueous solution such as a tetraammonium hydroxide (TMAH) aqueous solution can also be used in consideration of the influence on the substrate. The density can be appropriately selected according to the developing speed.
Although a resist pattern can be obtained through each of the above steps, a heating step at about 100 to 300 ° C. can be further performed in some cases. By carrying out this heating step, chemical resistance can be further improved. For heating, a hot-air, infrared, or far-infrared heating furnace can be used.

(4) Etching process The ITO film of the substrate exposed by development is etched. A conductor pattern is usually formed using an acidic etching solution such as cupric chloride-hydrochloric acid aqueous solution or ferric chloride-hydrochloric acid aqueous solution at 30 to 60 ° C. In addition to the etching solution, an oxalic acid aqueous solution can be used depending on the type of the ITO film or the base.

(5) Stripping step Thereafter, the resist pattern is stripped from the substrate using an aqueous solution having alkalinity stronger than the developer. The alkali aqueous solution for peeling is not particularly limited, but an aqueous solution of NaOH or KOH having a concentration of about 2 to 5% by mass and a temperature of about 40 to 70 ° C. is generally used. A small amount of a water-soluble solvent can also be added to the stripping solution.

Hereinafter, examples of embodiments of the present invention will be specifically described.
(Examples 1-10, Comparative Examples 1-3)
First, a method for producing samples for evaluation of Examples and Comparative Examples will be described, and then an evaluation method and evaluation results for the obtained samples will be shown.

1. Production of Evaluation Sample Evaluation samples in Examples and Comparative Examples were produced as follows.
<Preparation of photosensitive resin laminate>
The photosensitive resin composition prepared by thoroughly stirring and mixing the photosensitive resin composition and the solvent having the composition shown in Table 1 below (however, the number of each component indicates the blending amount (part by mass) as a solid content). A liquid coating was applied uniformly on the surface of a polyethylene terephthalate film having a thickness of 16 μm as a support using a bar coater, followed by drying in a dryer at 95 ° C. for 2.5 minutes to form a photosensitive resin layer. The thickness of the photosensitive resin composition layer was 25 μm.
Next, a 21 μm thick polyethylene film was laminated as a protective layer on the surface of the photosensitive resin layer on which the polyethylene terephthalate film was not laminated to obtain a photosensitive resin laminate.

  Table 2 below shows the names of the material components in the photosensitive resin composition preparation liquid indicated by abbreviations in Table 1.

  Comparative Example 1 is a composition that does not contain (D) an epoxy silane compound, Comparative Example 2 is a composition that does not contain (E) a thiol compound, and Comparative Example 3 contains (D) an epoxy silane compound. It is a composition containing excess.

<Board>
A 0.7 mm thick glass substrate (manufactured by Geomat Co., Ltd.) on which a 90 nm ITO film was laminated was prepared.

<Laminate>
While peeling the polyethylene film of the photosensitive resin composition laminate, it was laminated at a roll temperature of 110 ° C. with a hot roll laminator (VA-400III, manufactured by Taisei Laminator Co., Ltd.). The air pressure was 0.40 MPa, and the laminating speed was 1.5 m / min.

<Exposure>
Using a chrome glass photomask, exposure was performed at an exposure amount of 150 mJ / cm ² using a high-precision exposure machine EXM-1066-H-01 (ghi line, 23 W, gap exposure method 150 um) manufactured by Oak Manufacturing. Note that a line pattern mask having a ratio of 1: 1 between the exposed portion and the unexposed portion was used as the chromium glass photomask.

<Development>
After the polyethylene terephthalate film was peeled off, a 1 mass% Na ₂ CO ₃ aqueous solution at 30 ° C. was sprayed for a predetermined time to dissolve and remove the unexposed portion of the photosensitive resin layer. At this time, the shortest time required for completely dissolving the photosensitive resin layer in the unexposed portion was defined as the minimum development time, and development was performed under the same conditions twice as long as that to produce a cured resist pattern.

<Etching>
Etching is performed by immersing the above-mentioned glass substrate with a cured resist pattern on a ferric chloride-hydrochloric acid aqueous solution (ADEKA Co., Ltd., Adeka Kermica ITO-400) heated to 50 ° C. for 5 minutes. Was washed with water.

<Peeling>
Next, the etched glass substrate was immersed in a 3% by mass NaOH aqueous solution heated to 50 ° C. for 3 minutes to peel off the cured resist pattern.

2. Evaluation method <Adhesion evaluation>
The width between lines of the cured resist pattern was measured after development. Furthermore, the line width of the formed circuit pattern after etching was measured. The side etch width was calculated by comparing the line width of the cured resist pattern with the line width of the formed circuit pattern after etching. According to the value of side etch width, it was ranked as follows:
A: Side etch width value is 8.5 μm or less;
○: Side etch width value is more than 8.5 μm and not more than 12.0 μm;
X: The value of the side etch width exceeds 12.0 μm.

<Storage stability evaluation>
The polyethylene film is peeled from the photosensitive resin laminate, and after exposure for 15 minutes after exposure, the exposed portion is exposed from the polyethylene terephthalate side using a spectrometer (Nippon Denshoku Industries Co., Ltd., NF333). The contrast of the unexposed area was measured. In addition, the contrast of the same photosensitive resin laminate that was stored for 3 days at a temperature of 23 ° C. and a humidity of 75% was measured according to the same procedure, and ranked according to the difference as follows:
A: Contrast difference is 0.8 or less;
○: Contrast difference is more than 0.8 and 1.5 or less;
X: Contrast difference exceeds 1.5.

3. Evaluation results Table 1 shows the evaluation results of Examples 1 to 10 and Comparative Examples 1 to 3.

The present invention relates to a photosensitive resin composition useful for pattern formation such as forming an electrode on an ITO film or SnO ₂ film on a glass substrate used as a display material for a flat panel display, and a photosensitive resin laminate. It is useful when forming ITO electrodes in the production of display materials for flat panel displays.

Claims (12)

(A) Alkali-soluble resin 40-90 mass%, (B) 5-50 mass% of compound which has an ethylenically unsaturated double bond, (C) 1-20 mass% of photoinitiators, (D) Epoxysilane compound The photosensitive resin composition containing 0.001-2.5 mass% , ( E) thiol compound 0.005-1.0 mass% , and leuco crystal violet . The (E) thiol compound is represented by the following general formula (I):

{In the formula, R ₁ is a group having aromaticity. } The photosensitive resin composition of Claim 1 which is a thiol compound represented by these. The photosensitive resin composition according to claim 2, wherein the thiol compound represented by (E) the general formula (I) is a heterocyclic compound in which R ₁ has aromaticity. The thiol compound represented by the general formula (I) is represented by the following general formula (II):

{In the formula, R ₂ is a kind of group selected from the group consisting of SH, SR ₃ OR ₄ and NR ₃ R ₄ , and R ₃ and R ₄ are independently H, C 1-12. It is a kind of group selected from the group consisting of an alkyl group and an aryl group. } The photosensitive resin composition of Claim 2 which is a compound represented by these. The (E) thiol compound is represented by the following general formula (III):

{In the formula, R ₅ is a kind selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkylthio group having 1 to 3 carbon atoms, SH, and NR ₆ R ₇ . Each of R ₆ and R ₇ is independently a group selected from the group consisting of H, an alkyl group having 1 to 12 carbon atoms, and an aryl group. } The photosensitive resin composition of Claim 2 which is a compound represented by these. The (D) epoxysilane compound is represented by the following general formula (IV):

{In the formula, R ₈ is an alkyl group having 1 to 5 carbon atoms, A is an alkyl group having 1 to 4 carbon atoms or-(DO) _n- , and D is an alkyl group having 1 to 3 carbon atoms. N is an integer of 1 to 5, and B is the following general formula (V):

It is group which has the functional group represented by these. } The photosensitive resin composition of Claim 1 which is a compound represented by these.   2. The photosensitive resin composition according to claim 1, wherein a mass ratio of the (A) alkali-soluble polymer to the (B) compound having an ethylenically unsaturated double bond is 1.5 to 1.8: 1. .   The photosensitive resin laminated body by which the photosensitive resin layer which consists of the photosensitive resin composition of any one of Claims 1-7 was laminated | stacked on the support film.   A laminating step of laminating the photosensitive resin laminate according to claim 8 on a transparent electrode, an exposure step of exposing the laminate, and a developing step of developing the exposed laminate. A resist pattern forming method.   A method for producing an electrode, comprising etching the transparent electrode according to a resist pattern obtained by the pattern forming method according to claim 9.   A laminating step of laminating the photosensitive resin laminate according to claim 8 on an iron-based alloy, an exposure step of exposing the laminate, and a developing step of developing the exposed laminate. A resist pattern forming method.   A method for producing an iron-based alloy structure, comprising etching the iron-based alloy according to a resist pattern obtained by the pattern forming method according to claim 11.