Photosensitive element, resist pattern formation method, and wiring board production method

Abstract

This photosensitive element comprises, in order, a support film, a photosensitive layer, and a protection film. The photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and an anthracene sensitizer. The anthracene sensitizer includes an anthracene compound that has a C3 or fewer alkoxy group at the 9 position and the 10 position of an anthracene ring. The thickness of the photosensitive layer is at least 30 μm, and the light transmittance of the photosensitive layer at a wavelength of 405 nm is 25.0%–95.0%.

Description

Photosensitive element, method for forming resist pattern, and method for manufacturing wiring board

[0001] The present disclosure relates to a photosensitive element, a method for forming a resist pattern, and a method for manufacturing a wiring board.

[0002] In the manufacture of wiring boards, a resist pattern is formed to obtain the desired wiring. To form the resist pattern, a photosensitive element is widely used, which includes a support film, a layer formed on the support film using a photosensitive resin composition (hereinafter also referred to as a "photosensitive layer"), and a protective film laminated on the side of the photosensitive layer opposite the support film. The resist pattern can be formed by exposing and developing the photosensitive layer.

[0003] In recent years, with the trend toward miniaturization and increased density of electronic devices, there has been a demand for the formation of finer wiring than ever before on wiring substrates. To improve the resolution of the formed resist patterns, anthracene derivatives such as 9,10-dibutoxyanthracene have been investigated as sensitizers (see, for example, Patent Document 1).

[0004] International Publication No. 2007 / 004619

[0005] Photosensitive elements used in bump formation applications for forming copper pillars that connect IC chips and wiring substrates for semiconductor packages are required to form resist patterns such as via hole patterns with high resolution. However, the thicker the photosensitive layer, the more difficult it is to achieve uniform curing all the way to the bottom, making it difficult to form resist patterns with sufficient resolution and adhesion.

[0006] An object of the present disclosure is to provide a photosensitive element capable of forming a resist pattern with excellent resolution and adhesion, a method for forming a resist pattern, and a method for manufacturing a wiring board.

[0007] The present disclosure provides the following photosensitive element, method for forming a resist pattern, and method for manufacturing a wiring board. [1] A photosensitive element comprising a support film, a photosensitive layer, and a protective film, in this order, wherein the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and an anthracene-based sensitizer, the anthracene-based sensitizer containing an anthracene compound having alkoxy groups having 3 or fewer carbon atoms bonded to the 9th and 10th positions of the anthracene ring, the photosensitive layer having a thickness of 30 μm or more, and a light transmittance of the photosensitive layer at a wavelength of 405 nm of 25.0% to 95.0%. [2] The photosensitive element according to item [1] above, wherein the anthracene compound is at least one selected from the group consisting of 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 9,10-dipropoxyanthracene. [3] The photosensitive element according to [1] or [2] above, wherein the anthracene compound is 9,10-dimethoxyanthracene or 9,10-diethoxyanthracene. [4] The photosensitive element according to any one of [1] to [3] above, wherein the content of the anthracene-based sensitizer is 0.1 to 1.0 part by mass per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound. [5] The photosensitive element according to any one of [1] to [4] above, wherein the protective film is a polyethylene film. [6] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to any one of [1] to [5] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern. [7] A method for manufacturing a wiring board, comprising a step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to [6] above, to form a conductor pattern.

[0008] According to one aspect of the present disclosure, there is provided a photosensitive element capable of forming a resist pattern with excellent adhesion and resolution. According to another aspect of the present disclosure, there is provided a method for manufacturing a wiring board using the photosensitive element.

[0009] FIG. 1 is a schematic cross-sectional view illustrating a photosensitive element according to one embodiment.

[0010] Preferred embodiments of the present disclosure will be described in detail below, with reference to the drawings as necessary. It goes without saying that, in the following embodiments, the components (including element steps, etc.) are not necessarily essential unless otherwise specified or considered to be clearly essential in principle. The same applies to numerical values ​​and ranges, and they should not be construed as unduly limiting the present disclosure.

[0011] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. The term "layer" includes a structure having a shape formed on a part of a surface as well as a structure having a shape formed on the entire surface when observed in a plan view.

[0012] A numerical range "A or higher" means a range exceeding A and A. A numerical range "A or lower" means a range exceeding A and A. A numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more.

[0013] In this specification, "(meth)acrylic acid" means at least one of "acrylic acid" and the corresponding "methacrylic acid." The same applies to other similar expressions such as (meth)acrylate. "(Poly)oxyethylene group" means an oxyethylene group or a polyoxyethylene group in which two or more ethylene groups are linked by ether bonds. "(Poly)oxypropylene group" means an oxypropylene group or a polyoxypropylene group in which two or more propylene groups are linked by ether bonds. "EO-modified" means a compound having a (poly)oxyethylene group. "PO-modified" means a compound having a (poly)oxypropylene group. "EO / PO-modified" means a compound having a (poly)oxyethylene group and / or a (poly)oxypropylene group.

[0014] In this specification, when a composition contains a plurality of substances corresponding to each component, the amount of each component refers to the total amount of the plurality of substances present in the composition, unless otherwise specified. In this specification, the term "solid content" refers to the non-volatile content of the photosensitive resin composition excluding volatile substances (water, solvent, etc.). In other words, the term "solid content" refers to components other than the solvent that remain without volatilizing during drying of the photosensitive resin composition, as described below, and includes those that are liquid, syrup-like, or waxy at room temperature (25°C).

[0015] [Photosensitive Element] The photosensitive element according to this embodiment includes a support film, a photosensitive layer, and a protective film, in this order. The photosensitive layer contains (A) a binder polymer, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) an anthracene-based sensitizer, and the anthracene-based sensitizer contains an anthracene compound having alkoxy groups having 3 or less carbon atoms bonded to the 9th and 10th positions of the anthracene ring. The photosensitive layer has a thickness of 30 μm or more, and a light transmittance of 25.0% to 95.0% at a wavelength of 405 nm.

[0016] (Photosensitive layer) The photosensitive layer is a layer formed using a photosensitive resin composition containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and an anthracene-based sensitizer. The photosensitive resin composition according to this embodiment may further contain a polymerization inhibitor or other components as needed. Each component will be described below.

[0017] ((A) Binder Polymer) The photosensitive resin composition contains a binder polymer as component (A). The component (A) can have a polymerizable monomer as a monomer unit (structural unit), and can be obtained, for example, by radical polymerization of the polymerizable monomer.

[0018] Examples of the polymerizable monomer include (meth)acrylic acid, hydroxyalkyl (meth)acrylate, benzyl (meth)acrylate, styrene compounds (styrene or styrene derivatives), alkyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, and (meth)acrylic acid. Examples of suitable maleic anhydrides include diacetone (meth)acrylamide, (meth)acrylonitrile, vinyl alcohol ethers (vinyl-n-butyl ether, etc.), α-bromo(meth)acrylic acid, α-chloro(meth)acrylic acid, β-furyl(meth)acrylic acid, β-styryl(meth)acrylic acid, maleic acid, maleic anhydride, maleic acid monoesters (monomethyl maleate, monoethyl maleate, monoisopropyl maleate, etc.), fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid.

[0019] From the viewpoint of improving alkaline developability, the component (A) may have (meth)acrylic acid as a monomer unit. The content of (meth)acrylic acid in the component (A), based on the total amount of monomer units constituting the component (A), may be 1% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 23% by mass or more, or 25% by mass or more, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less. From these viewpoints, the content of the (meth)acrylic acid monomer unit may be, for example, 1 to 50% by mass, 10 to 45% by mass, 15 to 45% by mass, 20 to 40% by mass, 23 to 35% by mass, or 25 to 30% by mass.

[0020] From the viewpoint of improving alkaline developability, the component (A) may have a hydroxyalkyl (meth)acrylate as a monomer unit. Examples of the hydroxyalkyl (meth)acrylate include hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, and hydroxyhexyl (meth)acrylate.

[0021] The content of hydroxyalkyl (meth)acrylate in component (A) may be 0.1 mass% or more, 0.5 mass% or more, 1.0 mass% or more, 1.5 mass% or more, 2.0 mass% or more, 2.5 mass% or more, or 3.0 mass% or more, and may be 20 mass% or less, 15 mass% or less, 10 mass% or less, 5.0 mass% or less, 4.0 mass% or less, or 3.0 mass% or less, based on the total amount of monomer units constituting component (A). From these viewpoints, the content of hydroxyalkyl (meth)acrylate monomer units may be, for example, 0.1 to 20 mass%, 0.5 to 15 mass%, 1.0 to 10 mass%, 1.5 to 5.0 mass%, 2.0 to 4.0 mass%, or 2.5 to 3.0 mass%.

[0022] In order to form a resist pattern with even more excellent resolution, the component (A) may contain styrene or a styrene derivative as a monomer unit. Examples of styrene derivatives include vinyltoluene and α-methylstyrene.

[0023] The content of styrene or styrene derivative in component (A) may be 30% by mass or more, 32% by mass or more, 35% by mass or more, 40% by mass or more, or 42% by mass or more, and may be 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, or 50% by mass or less, based on the total amount of monomer units constituting component (A). From these viewpoints, the content of monomer units of styrene compounds may be, for example, 30 to 70% by mass, 32 to 65% by mass, 35 to 60% by mass, 40 to 55% by mass, or 42 to 50% by mass.

[0024] From the viewpoint of improving the adhesion and release properties of the resist pattern, the component (A) may contain benzyl (meth)acrylate as a monomer unit. The content of benzyl (meth)acrylate in the component (A) may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, and may be 40% by mass or less, 35% by mass or less, 30% by mass or less, or 25% by mass or less, based on the total amount of monomer units constituting the component (A). From these viewpoints, the content of the benzyl (meth)acrylate monomer unit may be, for example, 5 to 40% by mass, 5 to 35% by mass, 10 to 30% by mass, 10 to 25% by mass, or 15 to 25% by mass.

[0025] The component (A) may further contain structural units derived from other monomers in addition to the above-mentioned monomers. The other monomers may be, for example, (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters.

[0026] From the viewpoint of improving alkaline developability and release properties, the other monomer may preferably be a (meth)acrylic acid alkyl ester. The alkyl group of the (meth)acrylic acid alkyl ester may be, for example, a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, or a structural isomer thereof, and from the viewpoint of further improving release properties, may be an alkyl group having 1 to 4 carbon atoms.

[0027] From the viewpoint of enabling suitable development, the acid value of the (A) component may be 100 mgKOH / g or more, 120 mgKOH / g or more, 140 mgKOH / g or more, 150 mgKOH / g or more, 160 mgKOH / g or more, or 170 mgKOH / g or more, and from the viewpoint of improving the adhesion (developer resistance) of the cured product of the photosensitive resin composition, it may be 250 mgKOH / g or less, 240 mgKOH / g or less, 230 mgKOH / g or less, 200 mgKOH / g or less, or 190 mgKOH / g or less. The acid value of the (A) component can be adjusted by the content of structural units constituting the (A) component (for example, structural units derived from (meth)acrylic acid).

[0028] The acid value can be measured by the following procedure. First, 1 g of the binder polymer to be measured for acid value is precisely weighed, and then 30 g of acetone is added to the binder polymer to uniformly dissolve it, thereby obtaining a solution. Next, an appropriate amount of phenolphthalein, which serves as an indicator, is added to the solution, and then titration is performed using a 0.1 N aqueous solution of KOH (potassium hydroxide). The acid value is determined by calculating the mass (unit: mg) of KOH required to neutralize the acetone solution of the binder polymer.

[0029] The weight average molecular weight (Mw) of the component (A) may be 10,000 or more, 20,000 or more, 25,000 or more, or 30,000 or more from the viewpoint of excellent adhesion (developer resistance) of a cured product of the photosensitive resin composition, and from the viewpoint of suitable development, Mw may be 100,000 or less, 80,000 or less, 60,000 or less, 50,000 or less, or 40,000 or less. The dispersity (Mw / Mn) of the component (A) may be, for example, 1.0 or more or 1.5 or more, and from the viewpoint of further improving adhesion and resolution, it may be 3.0 or less or 2.5 or less.

[0030] The weight average molecular weight and dispersity can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. The GPC conditions are as follows: Pump: Hitachi L-6000 type (trade name, manufactured by Hitachi, Ltd.) Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (all manufactured by Resonac Corporation, trade names) Eluent: tetrahydrofuran Measurement temperature: 40°C Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (trade name, manufactured by Hitachi, Ltd.)

[0031] The content of the component (A), based on the total solid content of the photosensitive resin composition, may be 20% by mass or more, 30% by mass or more, or 40% by mass or more from the viewpoint of excellent film formability, and may be 90% by mass or less, 80% by mass or less, or 65% by mass or less from the viewpoint of even better sensitivity and resolution.

[0032] The content of the (A) component may be 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more, relative to 100 parts by mass of the total amount of the (A) component and the (B) component, from the viewpoint of excellent film formability, and may be 70 parts by mass or less, 65 parts by mass or less, or 60 parts by mass or less, from the viewpoint of further improving sensitivity and resolution.

[0033] (Photopolymerizable Compound (B)) The photosensitive resin composition contains a photopolymerizable compound as component (B). The component (B) may be any compound that polymerizes when exposed to light, and may be, for example, a compound having an ethylenically unsaturated bond. The component (B) may contain a polyfunctional monomer having two or more reactive groups that react with radicals. The component (B) may contain bisphenol A (meth)acrylate from the viewpoint of improving alkaline developability, resolution, and releasability after curing.

[0034] Examples of bisphenol A type (meth)acrylates include 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolypropoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolybutoxy)phenyl)propane, and 2,2-bis(4-((meth)acryloxypolyethoxypolypropoxy)phenyl)propane. From the viewpoint of further improving resolution and adhesion, the component (B) may contain 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane or 2,2-bis(4-((meth)acryloxypentaethoxy)phenyl)propane.

[0035] From the viewpoint of further improving resolution, the content of bisphenol A type (meth)acrylate may be 20% by mass or more, 30% by mass or more, or 40% by mass or more, and may be 100% by mass or less, 95% by mass or less, or 90% by mass or less, based on the total amount of component (B).

[0036] From the viewpoint of further suitably improving resolution and flexibility, component (B) may contain an α,β-unsaturated ester compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid. Examples of the α,β-unsaturated ester compound include polyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and EO-modified polypropylene glycol, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO-PO-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate.

[0037] From the viewpoint of improving sensitivity and adhesion, component (B) may contain a compound having three or more (meth)acryloyl groups. Examples of such a compound include trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO-PO-modified trimethylolpropane tri(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, EO-modified ditrimethylolpropane tetra(meth)acrylate, and EO-modified dipentaerythritol hexa(meth)acrylate.

[0038] The content of the α,β-unsaturated ester compound may be 20% by mass or more or 30% by mass or more, based on the total amount of the component (B), from the viewpoint of improving flexibility, and may be 70% by mass or less or 60% by mass or less, from the viewpoint of further improving resolution.

[0039] The photosensitive resin composition may contain, as component (B), a photopolymerizable compound other than the bisphenol A (meth)acrylate and the α,β-unsaturated ester compound.

[0040] Examples of other photopolymerizable compounds include nonylphenoxy polyethyleneoxy acrylate, phthalic acid compounds, (meth)acrylic acid alkyl esters, and photopolymerizable compounds having at least one cationically polymerizable cyclic ether group in the molecule (such as oxetane compounds). From the viewpoint of further suitably improving the resolution, adhesion, resist shape, and release properties after curing, the other photopolymerizable compound may be at least one selected from the group consisting of nonylphenoxy polyethyleneoxy acrylate and phthalic acid compounds.

[0041] Examples of nonylphenoxy polyethyleneoxyacrylates include nonylphenoxytriethyleneoxyacrylate, nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate, nonylphenoxynonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, and nonylphenoxyundecaethyleneoxyacrylate.

[0042] Examples of phthalic acid compounds include γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β'-(meth)acryloyloxyethyl-o-phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate.

[0043] When the component (B) contains other photopolymerizable compounds, the content of the other photopolymerizable compounds may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 30% by mass or less, 25% by mass or less, or 20% by mass or less, based on the total amount of the component (B), from the viewpoint of further suitably improving the resolution, adhesion, resist shape, and release properties after curing.

[0044] The content of the component (B) may be 20 to 60 parts by mass, 30 to 55 parts by mass, or 35 to 50 parts by mass, relative to 100 parts by mass of the total amount of the components (A) and (B).

[0045] (Photopolymerization initiator (C)) The photosensitive resin composition contains a photopolymerization initiator as component (C). The component (C) is not particularly limited as long as it can polymerize component (B), and can be appropriately selected from commonly used photopolymerization initiators.

[0046] Examples of the component (C) include hexaarylbiimidazole compounds; aromatic ketones such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanone-1; alkyl ...benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-benzyl quinones such as anthraquinone; benzoin ether compounds such as benzoin alkyl ether; benzoin compounds such as benzoin and alkylbenzoin; benzyl derivatives such as benzyl dimethyl ketal; and phosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethylbenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0047] From the viewpoint of suppressing penetration of component (D) into the polyethylene film, component (C) may contain a hexaarylbiimidazole compound. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. The hydrogen atom bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (e.g., a chlorine atom).

[0048] The hexaarylbiimidazole compound may be a 2,4,5-triarylimidazole dimer. Examples of 2,4,5-triarylimidazole dimers include 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-bis-(m-methoxyphenyl)imidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer. From the viewpoint of further suppressing the penetration of component (D) into the polyethylene film, the hexaarylbiimidazole compound is preferably 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, and more preferably 2,2-bis(o-chlorophenyl)-4,5-4',5'-tetraphenyl-1,2'-biimidazole.

[0049] From the viewpoint of further suppressing the penetration of component (D) into the polyethylene film, the content of the hexaarylbiimidazole compound may be 90 mass % or more, 95 mass % or more, or 99 mass % or more based on the total amount of component (C). Component (C) may consist solely of the hexaarylbiimidazole compound.

[0050] The content of component (C) may be 1.0 to 20 parts by mass, 2.0 to 15 parts by mass, 3.0 to 10 parts by mass, or 4.0 to 8.0 parts by mass, relative to 100 parts by mass of the total amount of component (A) and component (B). When the content of component (C) is within this range, it becomes easy to improve both sensitivity and resolution in a balanced manner.

[0051] ((D) Anthracene-Based Sensitizer) The photosensitive resin composition contains an anthracene-based sensitizer as component (D), which allows the composition to effectively utilize the absorption wavelength of the actinic rays used for exposure. Component (D) contains an anthracene compound having an anthracene ring and alkoxy groups having 3 or less carbon atoms bonded to the 9- and 10-positions of the anthracene ring.

[0052] By using an anthracene compound having a specific structure as component (D), when the protective film is a polyethylene film, migration of component (D) from the photosensitive layer to the polyethylene film can be suppressed. In contrast, when an anthracene compound in which alkoxy groups having 4 or more carbon atoms are bonded to the 9th and 10th positions of the anthracene ring (e.g., 9,10-dibutoxyanthracene) is used, migration to the polyethylene film is likely to occur. The inventors speculate that this is because alkoxy groups having 3 or fewer carbon atoms are less hydrophobic than alkoxy groups having 4 or more carbon atoms, making it difficult for component (D) to penetrate into the hydrophobic polyethylene film. Furthermore, by using an anthracene compound with excellent migration resistance as component (D), the amount of component (D) substantially contained in the photosensitive layer is less likely to decrease, thereby improving the sensitivity of the photosensitive layer.

[0053] The alkoxy group having 3 or less carbon atoms may be a methoxy group, an ethoxy group, or a propoxy group. A hydrogen atom constituting the anthracene ring may be substituted with at least one group selected from the group consisting of an alkyl group (e.g., an alkyl group having 1 to 12 carbon atoms), a halogeno group, a cyano group, a carboxy group, a phenyl group, an alkoxycarbonyl group (e.g., an alkoxycarbonyl group having 2 to 6 carbon atoms), and a benzoyl group.

[0054] Examples of component (D) include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 9,10-dipropoxyanthracene. Component (D) may contain at least one selected from the group consisting of 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 9,10-dipropoxyanthracene, and is preferably 9,10-dimethoxyanthracene or 9,10-diethoxyanthracene, since these compounds have superior migration resistance.

[0055] The content of the component (D) is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, even more preferably 0.2 parts by mass or more, and particularly preferably 0.25 parts by mass or more, relative to 100 parts by mass of the total amount of the components (A) and (B). From the viewpoint of improving the storage stability of the photosensitive element, the content of the component (D) is preferably 1.0 part by mass or less, more preferably 0.8 parts by mass or less, even more preferably 0.7 parts by mass or less, and particularly preferably 0.6 parts by mass or less. From the above viewpoints, the content of the component (D) may be 0.1 to 1.0 parts by mass, 0.15 to 0.8 parts by mass, 0.2 to 0.7 parts by mass, or 0.25 to 0.6 parts by mass.

[0056] The photosensitive resin composition according to this embodiment contains an anthracene compound having a specific structure as the component (D), and therefore can form a resist pattern with excellent resolution without the need to use a sensitizing aid such as a naphthalene compound in combination.

[0057] (E) Polymerization Inhibitor The photosensitive resin composition may further contain a polymerization inhibitor as component (E) from the viewpoint of suppressing polymerization in unexposed areas during resist pattern formation and further improving resolution. Examples of polymerization inhibitors include 4-tert-butylcatechol and 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl.

[0058] The content of the (E) component may be 0.001 parts by mass or more, 0.005 parts by mass or more, or 0.01 parts by mass or more, relative to 100 parts by mass of the total amount of the (A) component and the (B) component, from the viewpoints of sensitivity and resolution, and may be 0.10 parts by mass or less, 0.08 parts by mass or less, or 0.05 parts by mass or less, from the viewpoints of sensitivity and adhesion.

[0059] (Other Components) The photosensitive resin composition may further contain one or more other components in addition to the components described above. Examples of other components include hydrogen donors (such as bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, and N-phenylglycine), dyes (such as malachite green), tribromophenyl sulfone, photocoloring agents (such as leuco crystal violet), thermal color-developing inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, and thermal crosslinking agents. The content of the other components may be 0.005 parts by mass or more, or 0.01 parts by mass or more, and may be 20 parts by mass or less, or 10 parts by mass or less, relative to 100 parts by mass of the total amount of component (A) and component (B).

[0060] The photosensitive resin composition may further contain one or more organic solvents from the viewpoint of adjusting the viscosity. Examples of organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, and propylene glycol monomethyl ether. The photosensitive resin composition can be used, for example, by dissolving the above-mentioned components in an organic solvent to form a solution (hereinafter referred to as "coating liquid") having a solid content (non-volatile content) of approximately 30 to 60 mass%. The solid content refers to the remaining components after removing volatile components from the photosensitive resin composition solution.

[0061] The light transmittance of the photosensitive layer at a wavelength of 405 nm is 25.0% or more and 95.0% or less. When the light transmittance of the photosensitive layer at a wavelength of 405 nm is 25.0% or more, sufficient crosslinking density is easily obtained even at the bottom of the resist pattern, and deterioration of the resist shape can be suppressed. The light transmittance may be 28.0% or more, 30.0% or more, 32.0% or more, or 33.0% or more. When the light transmittance of the photosensitive layer at a wavelength of 405 nm is 95.0% or less, reflected light from the bottom of the resist pattern can be suppressed, the occurrence of resist skirts can be suppressed, and resolution can be improved. The light transmittance may be 90.0% or less, 80.0% or less, 70.0% or less, or 60.0% or less.

[0062] The light transmittance of the photosensitive layer at a wavelength of 405 nm was measured using a spectrophotometer U-3310 (manufactured by Hitachi High-Technologies Corporation) for the support film on which the photosensitive layer was formed. The measurement conditions were a slit of 2 nm, a scan speed of 300 nm / min, and a measurement range of 750 nm to 200 nm. The light transmittance of the photosensitive layer can be calculated by converting the measurement result using only the support film as a reference. The light transmittance measured by the above method is a value calculated including the amount of light scattered by the photosensitive layer and support film, i.e., it can be said to be a value without baseline correction due to scattered light. The light transmittance at a wavelength of 405 nm is derived from the absorbance of component (D), and the light transmittance of the photosensitive layer at a wavelength of 405 nm can be adjusted by adjusting the structure and content of component (D). Light transmittance can also be measured with reference to JIS K 0115 (2004).

[0063] The thickness of the photosensitive layer after drying (after volatilizing the organic solvent if the photosensitive resin composition contains an organic solvent) may be 30 to 100 μm. From the viewpoint of forming a resist pattern having a high aspect ratio, the thickness of the photosensitive layer may be 30 μm or more, 35 μm or more, 38 μm or more, 40 μm or more, or 45 μm or more, and from the viewpoint of releasability, the thickness may be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

[0064] (Support Film) The support film may be a polymer film having heat resistance and solvent resistance. Examples of the support film include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene-2,6-naphthalate (PEN), and polyolefin films such as polyethylene and polypropylene.

[0065] The haze of the support film may be 0.01 to 5.0%, 0.01 to 1.5%, 0.01 to 1.0%, or 0.01 to 0.5%. Haze can be measured using a commercially available haze meter (turbidity meter) in accordance with the method specified in JIS K7105. Haze can be measured using a commercially available turbidity meter such as NDH-5000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0066] The thickness of the support film may be 1 μm or more, 5 μm or more, or 10 μm or more from the viewpoint of easily preventing damage to the support film when peeling the support film from the photosensitive layer, and may be 100 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less from the viewpoint of easily and suitably exposing the support film through the support film.

[0067] (Protective Film) Examples of the protective film include polyester films such as polyethylene terephthalate films, and polyolefin films such as polyethylene films and polypropylene films. Polyethylene films tend to be less susceptible to static electricity compared to polyethylene terephthalate films, polypropylene films, etc. By using a polyethylene film as the protective film, it is possible to suppress misalignment of the photosensitive element during winding, and static electricity is less likely to be generated when the protective film is peeled off from the photosensitive layer, thereby suppressing damage to the photosensitive layer.

[0068] The thickness of the protective film may be 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more from the viewpoint of easily suppressing damage to the protective film when the photosensitive layer and the support film are laminated onto the substrate while peeling off the protective film, and may be 100 μm or less, 50 μm or less, 40 μm or less, 35 μm or less, or 30 μm or less from the viewpoint of easily improving productivity.

[0069] 1 is a schematic cross-sectional view showing a photosensitive element according to one embodiment. As shown in FIG. 1, the photosensitive element 1 includes a support film 2, a photosensitive layer 3 provided on the support film 2, and a protective film 4 provided on the side of the photosensitive layer 3 opposite to the support film 2.

[0070] The photosensitive element 1 can be obtained, for example, as follows. First, a photosensitive layer 3 is formed on a support film 2. The photosensitive layer 3 can be formed, for example, by applying a photosensitive resin composition containing an organic solvent to form a coating layer and drying this coating layer. Next, a protective film 4 is formed on the surface of the photosensitive layer 3 opposite to the support film 2.

[0071] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating, etc. The coating layer is dried so that the amount of organic solvent remaining in the photosensitive layer 3 is, for example, 2% by mass or less, and specifically, for example, at 70 to 150°C for about 5 to 30 minutes.

[0072] In another embodiment, the photosensitive element may further include other layers such as a cushion layer, an adhesive layer, a light absorbing layer, and a gas barrier layer.

[0073] The photosensitive element 1 may be, for example, in the form of a sheet, or may be in the form of a photosensitive element roll wound around a core. In the photosensitive element roll, the photosensitive element 1 is preferably wound with the support film 2 on the outside. The core is formed of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or the like. An end separator may be provided on the end face of the photosensitive element roll from the viewpoint of end face protection, and a moisture-proof end face separator may be provided from the viewpoint of edge fusion resistance. The photosensitive element 1 may be wrapped, for example, in a black sheet with low moisture permeability.

[0074] The photosensitive element 1 can be suitably used for forming a resist pattern, and can be particularly suitably used in the method for manufacturing a wiring board, which will be described later.

[0075] [Method of Forming Resist Pattern] The method of forming a resist pattern according to this embodiment includes the steps of forming a photosensitive layer on a substrate using the photosensitive element (photosensitive layer forming step), irradiating at least a portion (predetermined portion) of the photosensitive layer with actinic light to form a photocured portion (exposure step), and removing at least a portion of the unphotocured portion from the substrate (development step), and may include other steps as necessary. The resist pattern can also be referred to as a photocured product pattern of a photosensitive resin composition or a relief pattern. The method of forming a resist pattern can also be referred to as a method of manufacturing a substrate with a resist pattern.

[0076] (Photosensitive Layer Forming Step) In the photosensitive layer forming step, a photosensitive layer is formed on a substrate using the photosensitive element described above. The substrate is not particularly limited, but typically, a circuit-forming substrate having an insulating layer and a conductor layer formed on the insulating layer, or a die pad (lead frame substrate) such as an alloy substrate is used.

[0077] For example, the photosensitive layer can be formed on the substrate by removing the protective film and then pressing the photosensitive layer of the photosensitive element onto the substrate while heating, thereby obtaining a laminate having the substrate, photosensitive layer, and support film in this order.

[0078] The photosensitive layer forming step may be carried out under reduced pressure from the viewpoint of adhesion and followability. Heating during pressure bonding may be carried out at a temperature of 70 to 130°C, and pressure bonding may be carried out at 0.1 to 1.0 MPa (1 to 10 kgf / cm ２ These conditions can be appropriately selected as needed. Note that if the photosensitive layer of the photosensitive element is heated to 70 to 130°C, it is not necessary to preheat the substrate, but the substrate can be preheated in order to further improve the adhesion and followability.

[0079] (Exposure Step) In the exposure step, the photosensitive layer is exposed to actinic rays through the support film, whereby the exposed areas irradiated with the actinic rays are photocured to form photocured areas (latent images).

[0080] As the exposure method, known exposure methods can be applied, and examples thereof include a method of irradiating an actinic ray in an imagewise manner through a negative or positive mask pattern called artwork (mask exposure method), a method of irradiating an actinic ray projected from an image of a photomask through a lens (projection exposure method), and a method of irradiating an actinic ray in an imagewise manner (direct writing exposure method) such as LDI (Laser Direct Imaging) exposure method and DLP (Digital Light Processing) exposure method.

[0081] The light source for actinic rays is not particularly limited as long as it is a commonly used known light source, and examples thereof include those that effectively emit ultraviolet rays, such as carbon arc lamps, mercury vapor arc lamps, ultra-high pressure mercury lamps, high pressure mercury lamps, xenon lamps, gas lasers such as argon lasers, solid state lasers such as YAG lasers, and semiconductor lasers such as gallium nitride blue-violet lasers. Among these, from the viewpoint of improving resolution and alignment in a well-balanced manner, a light source capable of emitting i-line monochromatic light with a wavelength of 365 nm, a light source capable of emitting h-line monochromatic light with a wavelength of 405 nm, or a light source capable of emitting actinic rays with exposure wavelengths that are crossed by i, h, and g may be used.

[0082] (Post-Exposure Heat Treatment Step) In the method for forming a resist pattern according to this embodiment, from the viewpoint of improving adhesion, post-exposure baking (PEB) may be performed after the exposure step and before the development step. The temperature when performing PEB may be 50 to 100° C. The heater may be a hot plate, a box-type dryer, a heating roll, or the like.

[0083] (Developing Step) In the developing step, the support film is peeled off, and then the uncured portions of the photosensitive layer are removed from the substrate. By the developing step, a resist pattern consisting of the photocured portions of the photosensitive layer is formed on the substrate. The developing method may be wet development or dry development, and wet development is preferred.

[0084] In the case of wet development, development can be carried out by a known wet development method using a developer suitable for the photosensitive resin composition. Examples of wet development methods include dipping, puddling, high-pressure spraying, brushing, scrubbing, and swinging immersion. These wet development methods may be used alone or in combination of two or more methods.

[0085] The developer is appropriately selected depending on the composition of the photosensitive resin composition, and examples of the developer include alkaline aqueous solutions and organic solvent developers.

[0086] From the viewpoints of safety, stability, and ease of use, an alkaline aqueous solution may be used as the developer. Examples of the base for the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide, alkali carbonates such as carbonates or bicarbonates of lithium, sodium, potassium, or ammonium, alkali metal phosphates such as potassium phosphate and sodium phosphate, alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate, sodium borate, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol, 1,3-diamino-2-propanol, and morpholine.

[0087] Examples of alkaline aqueous solutions that can be used include a dilute solution of 0.1 to 5% by mass sodium carbonate, a dilute solution of 0.1 to 5% by mass potassium carbonate, a dilute solution of 0.1 to 5% by mass sodium hydroxide, and a dilute solution of 0.1 to 5% by mass sodium tetraborate. The pH of the alkaline aqueous solution used for development may be in the range of 9 to 11, and the temperature of the alkaline aqueous solution can be adjusted according to the developability of the photosensitive layer. The alkaline aqueous solution may contain, for example, a surfactant, an antifoaming agent, or a small amount of an organic solvent to promote development.

[0088] Examples of organic solvents used in the alkaline aqueous solution include 3-acetone alcohol, acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0089] Examples of organic solvents used in the organic solvent developer include 1,1,1-trichloroethane, N-methyl-2-pyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. From the viewpoint of preventing ignition, these organic solvents may be used as the organic solvent developer by adding water in a range of 1 to 20% by mass.

[0090] (Other Steps) In the method for forming a resist pattern according to this embodiment, after removing the uncured portion in the development step, heating at 60 to 250° C. or 0.2 to 10 J / cm 2 is performed as needed. ２ The method may further include a step of hardening the resist pattern by exposing the resist pattern to light at an exposure dose of 1000 ppm or more.

[0091] [Method for manufacturing wiring board] The method for manufacturing a wiring board according to this embodiment includes a step of forming a conductor pattern by etching or plating a substrate on which a resist pattern has been formed by the above-described method for forming a resist pattern, and may also include other steps such as a resist pattern removal step, as necessary.

[0092] In the etching process, a resist pattern formed on a substrate is used as a mask to etch away the conductive layer provided on the substrate, thereby forming a conductive pattern. The etching method is appropriately selected depending on the conductive layer to be removed. Examples of etching solutions include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide-based etching solution.

[0093] In the plating process, a conductive layer provided on a substrate is plated using a resist pattern formed on the substrate as a mask. After the plating process, the resist may be removed by removing the resist pattern as described below, and the conductive layer covered with the resist may be etched to form a conductive pattern. The plating method may be electrolytic plating.

[0094] After the etching or plating process, the resist pattern on the substrate is removed. The resist pattern can be removed, for example, using an inorganic alkaline stripper or an organic alkaline stripper. Examples of inorganic alkaline stripper solutions that can be used include a 1 to 10 mass % aqueous solution of sodium hydroxide and a 1 to 10 mass % aqueous solution of potassium hydroxide. Examples of organic alkaline stripper solutions that can be used include amine-based strippers such as ethanolamine, ethylenediamine, and diethylenetriamine, and tetramethylammonium hydroxide aqueous solutions. From the viewpoint of the strippability of thick-film resist patterns, organic alkaline stripper solutions may also be used.

[0095] Methods for removing the resist pattern include, for example, a dipping method and a spray method, which may be used alone or in combination.

[0096] When the resist pattern is removed after plating, the conductor layer covered with the resist is further etched by etching to form a conductor pattern, thereby manufacturing a desired printed wiring board. The etching method used here is appropriately selected depending on the conductor layer to be removed. For example, the above-mentioned etching solution can be used.

[0097] The method for manufacturing a wiring board according to this embodiment can be applied to the manufacture of not only single-layer wiring boards but also multi-layer wiring boards, and can also be applied to the manufacture of wiring boards having small-diameter through holes.

[0098] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples.

[0099] [Photosensitive Resin Composition] Each photosensitive resin composition was prepared by mixing the components in the amounts (parts by mass) shown in Table 1 with 4.5 parts by mass of acetone, 16 parts by mass of toluene, and 4 parts by mass of methanol. The amounts (parts by mass) of each component shown in Table 1 are the masses of nonvolatile components (solid content). Details of each component shown in Table 1 are as follows.

[0100] (Component (A)) A1: ethylene glycol monomethyl ether / toluene solution (solid content: 47% by mass) of a copolymer of methacrylic acid / methyl methacrylate / styrene / benzyl methacrylate (mass ratio: 27 / 5 / 45 / 23, Mw: 47,000, acid value: 176.1 mg KOH / g, Tg: 107°C) (Component (B)) B1: 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (average 10 mol EO adduct, molecular weight: 804, manufactured by Resonac Corporation, trade name "FA-321M") (Component (C)) BCIM: 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole (manufactured by Hampford Chemical Industry Co.) (Component (D)) D1: 9,10-diethoxyanthracene (manufactured by Air Water Performance Chemicals Inc., trade name "UVS-1101") D2: 9,10-dibutoxyanthracene (manufactured by Air Water Performance Chemicals Inc., trade name "UVS-1331") (Component (E)) TBC: 4-tert-butylcatechol (manufactured by DIC Corporation, trade name "DIC-TBC") (Other Components) LCV: Leuco Crystal Violet (manufactured by Yamada Chemical Industry Co., Ltd.) MKG: Malachite Green (manufactured by Osaka Organic Chemical Industry Ltd.) SF-808H: Mixture of carboxybenzotriazole, 5-amino-1H-tetrazole, and methoxypropanol (manufactured by Sanwa Chemical Co., Ltd.)

[0101] [Photosensitive element] A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "FB-40") was prepared as a support film. The photosensitive resin composition was applied to the support film and then dried in a hot air convection dryer at 80°C and 120°C sequentially to form a photosensitive layer having a thickness of 40 μm after drying. A polyethylene film (manufactured by Tamapoly Corporation, product name "NF-15") was laminated to the photosensitive layer as a protective film to obtain a photosensitive element comprising a support film, a photosensitive layer, and a protective film.

[0102] (Light Transmittance) After peeling off the protective film from the photosensitive element, the absorption spectra of the photosensitive layer and support film were measured using an ultraviolet-visible spectrophotometer (manufactured by Hitachi High-Technologies Corporation, product name "Hitachi Spectrophotometer U-3310"). The measurement was performed using a polyethylene terephthalate film (FB-40) as a reference under the following conditions: temperature 20°C, slit 2 nm, scan speed 300 nm / min, sampling interval 0.50 nm, and wavelength range 750 nm to 200 nm. The light transmittance of the photosensitive layer was calculated from the absorbance at a wavelength of 405 nm.

[0103] [Evaluation] The following evaluations were carried out using the photosensitive element. The results are shown in Table 1.

[0104] (Migration Resistance) The photosensitive element was stored at 15°C for 7 days, and then the protective film was peeled off. The absorption spectrum of the protective film was measured using an ultraviolet-visible spectrophotometer (U-3310). The measurement was performed under the following conditions: temperature 20°C, slit width 2 nm, scan speed 300 nm / min, sampling interval 0.50 nm, and measurement range 750 nm to 200 nm. The lower the absorbance value at 405 nm derived from component (D) of the protective film, the more excellent the migration resistance.

[0105] [Laminate L1] A copper-clad laminate (manufactured by Resonac Corporation, product name "MCL-E-67") comprising a glass epoxy material and copper foil (thickness: 16 μm) arranged on both sides thereof was pickled, washed with water, and then dried with an air flow. The copper-clad laminate was then heated to 80°C, and the protective film was peeled off. A photosensitive element was then laminated onto the copper-clad laminate so that the photosensitive layer was in contact with the copper surface, thereby obtaining a laminate L1 comprising, in order, a copper-clad laminate, a photosensitive layer, and a support film. Lamination was performed using a 110°C heat roll at a pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0106] [Laminate L2] The above-mentioned photosensitive element was laminated onto a Cu-sputtered PET film (manufactured by Geomatec Co., Ltd., thickness: 125 μm) so that the photosensitive layer was in contact with the copper surface while peeling off the protective film, thereby obtaining a laminate L2 comprising the Cu-sputtered PET film, the photosensitive layer, and the support film in that order. The lamination was performed using a heat roll at 110°C, with a pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0107] (Minimum Development Time) The laminate L1 was cut into a square (5 cm x 5 cm) and the support film was peeled off to obtain a test piece. Next, the unexposed photosensitive layer of the test piece was spray-developed at a pressure of 0.18 MPa using a 1% by mass aqueous sodium carbonate solution at 30°C, and the shortest time at which it was visually confirmed that 1 mm or more of the unexposed photosensitive layer had been removed was defined as the minimum development time (MD). A full cone type nozzle was used for spray development. The distance between the test piece and the nozzle tip was 6 cm, and the nozzle was positioned so that the center of the test piece coincided with the center of the nozzle. The shorter the minimum development time (unit: seconds), the better the developability.

[0108] (Sensitivity) After placing a Hitachi 41-step step tablet on the support film of the laminate L1, the photosensitive layer was exposed through the support film using a direct imaging exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name "FDi-Ms") with a blue-violet laser diode having a wavelength of 405 nm as a light source, at an exposure amount (amount of irradiation energy) such that the number of remaining steps of the Hitachi 41-step step tablet was 15. The exposure amount at this time (unit: mJ / cm ２ The sensitivity (photosensitivity) was evaluated by the following formula: The lower the exposure amount, the higher the sensitivity.

[0109] (Adhesion) Using a drawing pattern in which line width (L) / space width (S) was x / 3x (x = 3 to 30, unit: μm, 1 μm intervals), the photosensitive layer of laminate L1 was exposed using a direct writing exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15. Post-exposure baking (PEB) was performed at 80°C for 30 seconds within 3 minutes after exposure.

[0110] (Resolution) Using a drawing pattern in which the line width (L) / space width (S) ratio was 3x / x (x = 3 to 30, unit: μm, 1 μm intervals), the photosensitive layer of the laminate L1 was exposed using a direct writing exposure machine (FDi-Ms) at an exposure dose such that the number of remaining steps on a Hitachi 41-step step tablet was 15. Within 3 minutes after exposure, post-exposure baking (PEB) was performed at 80°C for 30 seconds.

[0111] After PEB, the support film was peeled off from the laminate L1 to expose the photosensitive layer, and the unexposed portions were removed by spraying a 1% by mass aqueous sodium carbonate solution at 30°C for twice the minimum development time. After development, the space portions (unexposed portions) were removed without residue, and the line portions (exposed portions) were formed without meandering or chipping. Resolution was evaluated based on the minimum space width (unit: μm) in the resist pattern, and adhesion was evaluated based on the minimum line width (unit: μm) in the resist pattern. For both resolution and adhesion, the smaller the numerical value, the better the performance.

[0112] (Round Hole Resolution) Using a via pattern (via hole pattern) in which the diameter of the round hole opening / the center-to-center pitch of the round holes was x / 2x (x = 10 to 50, unit: μm, 1 μm intervals), the photosensitive layer of the laminate L2 was exposed using a direct imaging exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15. Within 3 minutes after exposure, post-exposure baking (PEB) was performed at 80°C for 30 seconds.

[0113] After PEB, the support film was peeled off from the laminate L2 to expose the photosensitive layer, and the unexposed areas were removed by spraying a 1% by weight aqueous sodium carbonate solution at 30°C for twice the minimum development time. The formed via pattern (via hole pattern) was observed with an optical microscope, and the round hole resolution was evaluated based on the value of the smallest via pattern diameter among the via patterns arranged in a lattice pattern that were completely removed (opened). The smaller this value, the better the round hole resolution.

[0114]

[0115] 1... photosensitive element, 2... support film, 3... photosensitive layer, 4... protective film

Claims

1. A photosensitive element comprising a support film, a photosensitive layer, and a protective film in this order, wherein the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and an anthracene-based sensitizer, and the anthracene-based sensitizer contains an anthracene compound having alkoxy groups with 3 or less carbon atoms bonded to the 9th and 10th positions of the anthracene ring, and wherein the photosensitive layer has a thickness of 30 μm or more and a light transmittance of 25.0% or more and 95.0% or less at a wavelength of 405 nm.

2. The photosensitive element of claim 1, wherein the anthracene compound is at least one selected from the group consisting of 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 9,10-dipropoxyanthracene.

3. The photosensitive element of claim 1, wherein the anthracene compound is 9,10-dimethoxyanthracene or 9,10-diethoxyanthracene.

4. The photosensitive element according to claim 1, wherein the content of the anthracene-based sensitizer is 0.1 to 1.0 part by mass per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

5. The photosensitive element of claim 1, wherein the protective film is a polyethylene film.

6. A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to any one of claims 1 to 5; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

7. A method for manufacturing a wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to claim 6, to form a conductor pattern.

Images