JP7507862B2 - Alkali-soluble resin, photosensitive resin composition, photosensitive element, method for forming resist pattern, and method for forming wiring pattern - Google Patents

Description

The present invention relates to an alkali-soluble resin, a photosensitive resin composition, a photosensitive element, a method for forming a resist pattern, and a method for forming a wiring pattern.

In the field of printed wiring board manufacturing, photosensitive resin compositions and photosensitive elements comprising a layer formed on a support film using the photosensitive resin composition (hereinafter also referred to as a "photosensitive layer") are widely used as resist materials for etching, plating, and the like.

A printed wiring board is manufactured using the above-mentioned photosensitive element, for example, by the following procedure. That is, first, the photosensitive layer of the photosensitive element is laminated onto a circuit-forming substrate such as a copper-clad laminate. Next, the photosensitive layer is exposed to light through a mask film or the like to form a photocured portion. At this time, the support film is peeled off before or after exposure. Thereafter, the area of the photosensitive layer other than the photocured portion is removed with a developer to form a resist pattern. Next, the resist pattern is used as a resist to perform an etching process or a plating process to form a conductor pattern, and finally the photocured portion of the photosensitive layer (resist pattern) is peeled off (removed).

In view of the impact on the environment, aqueous-based stripping solutions have begun to be used to strip resist patterns, instead of the amine-based stripping solutions that have been used in the past (see, for example, Patent Document 1).

JP 2013-061556 A

Photosensitive resin compositions are required to not only form resist patterns with high developability in unexposed areas and excellent resolution, but also to have excellent peeling properties in photocured areas in order to peel and remove the resist pattern. In contrast, when an aqueous-based stripper is used, the resist pattern takes longer to peel off than an amine-based stripper, and the peeled pieces tend not to break into small pieces. One way to improve the peeling properties is to increase the hydrophilicity of the binder resin contained in the photosensitive layer, but the exposed parts of the photosensitive layer tend to swell during development, decreasing the resolution. On the other hand, if you try to increase the hydrophobicity of the binder resin, not only will the developability of the unexposed parts decrease, but it will also be difficult to shorten the peeling time of the resist pattern and to break the peeled pieces into small pieces.

The present invention aims to provide an alkali-soluble resin used in a photosensitive resin composition having excellent developability, resolution, and peeling properties, a photosensitive resin composition containing the alkali-soluble resin, a photosensitive element, a method for forming a resist pattern, and a method for forming a wiring pattern.

One aspect of the present invention relates to an alkali-soluble resin that contains a structural unit having a polarity conversion group and a structural unit having a carboxy group, and the polarity conversion group has a group that does not leave under weak alkaline conditions but leaves under strong alkaline conditions.

In another aspect, the present invention relates to a photosensitive resin composition containing a binder resin including the above-mentioned alkali-soluble resin, a photopolymerizable compound, and a photopolymerization initiator.

In another aspect, the present invention relates to a photosensitive element comprising a support and a photosensitive layer formed on the support, the photosensitive layer containing the above-mentioned photosensitive resin composition.

In another aspect, the present invention relates to a method for forming a resist pattern, comprising the steps of forming a photosensitive layer on a substrate using the photosensitive resin composition or photosensitive element, irradiating at least a portion of the photosensitive layer with active light to form a photocured portion, and removing at least a portion of the photosensitive layer other than the photocured portion from the substrate.

In another aspect, the present invention relates to a method for forming a wiring pattern, which includes a step of forming a conductor pattern by etching or plating a substrate on which a resist pattern has been formed by the resist pattern forming method.

The present invention provides an alkali-soluble resin used in a photosensitive resin composition having excellent developability, resolution, and peeling properties, a photosensitive resin composition containing the alkali-soluble resin, a photosensitive element, a method for forming a resist pattern, and a method for forming a wiring pattern.

FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a photosensitive element.

The following describes in detail the embodiments of the present invention. However, the present invention is not limited to the following embodiments.

In this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. A numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum and maximum values, respectively. The term "layer" includes a structure that is formed over the entire surface when observed in a plan view, as well as a structure that is formed on a part of the surface. "(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)acryloyl.

In this specification, the amount of each component in the photosensitive resin composition means the total amount of the multiple substances present in the photosensitive resin composition when there are multiple substances corresponding to each component, unless otherwise specified. In the numerical ranges described in this specification, the upper and lower limits of the numerical ranges may be replaced with values shown in the examples. In addition, the present invention also includes embodiments in which the descriptions in this specification are combined in any manner. In this specification, the "solid content" refers to the non-volatile content excluding volatile substances such as water and solvent contained in the photosensitive resin composition. In other words, the "solid content" refers to components other than the solvent that remain without volatilization during drying of the photosensitive resin composition described later, and also includes liquid, starch syrup, and wax-like components at room temperature (25°C).

[Alkali-soluble resin]
The alkali-soluble resin according to this embodiment contains a structural unit having a polarity conversion group and a structural unit having a carboxy group, and the polarity conversion group has a group that does not leave under weak alkaline conditions but leaves under strong alkaline conditions.

An alkali-soluble resin is a resin that is soluble in an alkaline aqueous solution. Examples of alkaline aqueous solutions include tetramethylammonium hydroxide (TMAH) aqueous solutions, metal hydroxide aqueous solutions, metal carbonate aqueous solutions, and organic amine aqueous solutions. The solubility of a resin in an alkaline aqueous solution can be confirmed, for example, as follows.

A varnish obtained by dissolving a resin in a solvent is spin-coated onto a substrate such as a silicon wafer to form a coating film of about 5 μm in thickness. This is then immersed in either an aqueous TMAH solution, an aqueous metal hydroxide solution, an aqueous metal carbonate solution, or an aqueous organic amine solution at 20-25°C. If the coating film can be uniformly dissolved as a result of this, the resin can be considered to be soluble in an alkaline aqueous solution.

In this embodiment, the "polarity conversion group" refers to a functional group whose polarity changes from hydrophobic to hydrophilic. The polarity conversion group according to this embodiment is stable and hydrophobic under weak alkaline conditions, but can decompose under strong alkaline conditions to generate hydrophilic groups such as hydroxyl groups and carboxyl groups. An example of a weak alkaline condition is development of a photosensitive layer with an alkaline aqueous solution in the formation of a resist pattern, which will be described later. An example of a strong alkaline condition is stripping of a formed resist pattern with an alkaline aqueous solution. That is, the polarity conversion group according to this embodiment is a group that is stable and hydrophobic in the weak alkaline aqueous solution used in the development of the photosensitive layer, and can be decomposed by the strong alkaline aqueous solution used in the stripping of the resist pattern to change into a hydrophilic group.

The alkali-soluble resin according to this embodiment can be used as a binder resin for a photosensitive resin composition, and can improve the developability, resolution, and peeling properties of a photosensitive layer formed from the photosensitive resin composition. In addition, by using the alkali-soluble resin according to this embodiment in a photosensitive resin composition for thick film applications, it is possible to improve the peeling properties while maintaining the resolution.

From the viewpoint of release properties, the alkali-soluble resin contains a structural unit having a polarity conversion group. From the viewpoint of further improving the release properties, the polarity conversion group may be a group represented by the following formula (1).

In formula (1), ^R2 represents a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, or a trityl group. The group represented by formula (1) can be converted to "-OH" by elimination of ^R2 under strong alkaline conditions.

From the viewpoint of achieving an excellent balance between resolution and peeling properties, the structural unit having the polarity conversion group may be a structural unit based on a compound represented by the following formula (2):

In formula (2), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents an alkylene group having 1 to 6 carbon atoms, and R ² represents a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, or a trityl group. From the viewpoint of improving alkali solubility, L ¹ is preferably an alkylene group having 1 to 4 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, and even more preferably an alkylene group having 2 or 3 carbon atoms.

Examples of compounds represented by formula (2) include 2-(trimethylsilyloxy)ethyl (meth)acrylate, trimethylsilyl (meth)acrylate, and trityl (meth)acrylate.

The alkali-soluble resin according to this embodiment can be produced, for example, by radical polymerization of a monomer having a polar conversion group and a monomer having a carboxy group.

From the viewpoint of further improving the release properties, the content of the monomer having a polar conversion group may be 1% by mass or more, 2% by mass or more, 3% by mass or more, or 4% by mass or more based on the total amount of the monomers constituting the alkali-soluble resin. From the viewpoint of further improving the developability, the content of the monomer having a polar conversion group may be 35% by mass or less, 30% by mass or less, or 25% by mass or less.

From the viewpoint of alkaline developability, the alkali-soluble resin contains a structural unit having a carboxy group. Examples of monomers having a carboxy group include (meth)acrylic acid, α-bromoacrylic acid, α-chloroacrylic acid, β-furyl(meth)acrylic acid, β-styryl(meth)acrylic acid, maleic acid, maleic anhydride, maleic acid monoesters such as monomethyl maleate, monoethyl maleate, and monoisopropyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. From the viewpoint of further improving alkaline developability, the monomer having a carboxy group may be (meth)acrylic acid or methacrylic acid.

In order to improve the alkaline developability and alkaline resistance in a well-balanced manner, the content of structural units derived from monomers having a carboxy group may be 10 to 45 mass %, 15 to 40 mass %, or 20 to 35 mass % based on the total amount of monomers constituting the alkali-soluble resin. If this content is 10 mass % or more, the alkaline developability tends to be improved, and if it is 45 mass % or less, the alkaline resistance tends to be excellent.

From the viewpoint of adhesion and peeling properties, the alkali-soluble resin may have a structural unit based on styrene or a styrene derivative. Styrene derivatives are polymerizable compounds in which hydrogen atoms at the α-position or aromatic ring of styrene, such as vinyltoluene and α-methylstyrene, are substituted. The content of structural units based on styrene or a styrene derivative in the alkali-soluble resin may be 10 to 60 mass%, 15 to 55 mass%, or 25 to 50 mass%. If this content is 10 mass% or more, adhesion tends to improve, and if it is 60 mass% or less, it is possible to prevent the peeled pieces from becoming large during development, and the time required for peeling tends to be suppressed from increasing.

From the viewpoint of resolution and aspect ratio, the alkali-soluble resin may have structural units based on benzyl (meth)acrylic acid ester. From the viewpoint of improving resolution, the content of structural units derived from benzyl (meth)acrylic acid ester in the alkali-soluble resin may be 5 to 50% by mass, 15 to 45% by mass, or 10 to 40% by mass.

From the viewpoint of improving plasticity, the alkali-soluble resin may have a structural unit based on an alkyl (meth)acrylate ester. Examples of alkyl (meth)acrylate esters include methyl (meth)acrylate ester, ethyl (meth)acrylate ester, propyl (meth)acrylate ester, butyl (meth)acrylate ester, pentyl (meth)acrylate ester, hexyl (meth)acrylate ester, heptyl (meth)acrylate ester, octyl (meth)acrylate ester, 2-ethylhexyl (meth)acrylate ester, nonyl (meth)acrylate ester, decyl (meth)acrylate ester, undecyl (meth)acrylate ester, and dodecyl (meth)acrylate ester.

From the viewpoint of improving resolution, the weight average molecular weight (Mw) of the alkali-soluble resin may be 1000 or more, 2000 or more, 3000 or more, or 5000 or more. From the viewpoint of suitable development, the Mw of the alkali-soluble resin may be 30000 or less, 28000 or less, 26000 or less, or 24000 or less. Mw can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene.

The hydrophilicity of the alkali-soluble resin can be calculated from the hydrophilicity of the monomers constituting the alkali-soluble resin and the copolymerization ratio of the monomers by the following formula: The hydrophilicity of the monomer is the amount of water (mass%) contained in the monomer, which is measured by the Karl Fischer method after adding ion-exchanged water to the monomer and leaving it at 23° C. for 12 hours.
Hydrophilicity of alkali-soluble resin = copolymerization ratio of monomer (mass%) x hydrophilicity of monomer

The hydrophilicity of the alkali-soluble resin before the polarity conversion group is decomposed may be 80 to 120, 82 to 115, or 84 to 110 from the viewpoint of alkali resistance during development of the exposed area. The hydrophilicity of the alkali-soluble resin after the polarity conversion group is decomposed may be 95 to 120, 98 to 115, or 100 to 110 from the viewpoint of peeling properties. From the viewpoint of further improving the balance of developability, resolution, and peeling properties, the increase rate of hydrophilicity after polarity conversion may be 3 to 45%, 5 to 40%, or 10 to 35%.

[Photosensitive resin composition]
The photosensitive resin composition according to the present embodiment contains (A) a binder resin (hereinafter, sometimes referred to as "component (A)"), (B) a photopolymerizable compound (hereinafter, sometimes referred to as "component (B)"), and (C) a photopolymerization initiator (hereinafter, sometimes referred to as "component (C)"). Each component that may be contained in the photosensitive resin composition will be described in detail below.

<(A) Binder Resin>
The binder resin, which is the component (A), contains an alkali-soluble resin according to this embodiment (hereinafter, may be referred to as "component (A1)"). By containing the component (A1), the alkali resistance during development of the exposed area is improved, and a resist pattern with excellent resolution can be formed. The resist pattern can be peeled off with a strong alkaline aqueous solution. The component (A1) may be composed of only one type of resin, or may contain two or more types of resins.

Component (A) may further contain an alkali-soluble resin other than component (A1). The alkali-soluble resin may be a resin having a phenolic hydroxyl group. Examples of resins having a phenolic hydroxyl group include hydroxystyrene-based resins such as polyhydroxystyrene and copolymers containing hydroxystyrene as a monomer unit, phenolic resins, polybenzoxazole precursors such as poly(hydroxyamide), poly(hydroxyphenylene) ether, and polynaphthol.

The content of component (A) may be 30 to 90 parts by weight, 40 to 85 parts by weight, or 50 to 80 parts by weight, based on 100 parts by weight of the total amount of components (A) and (B). When the content of component (A) is within this range, the strength of the photocured portion of the photosensitive layer is improved.

<(B) Photopolymerizable Compound>
The (B) component is a compound having a functional group having an ethylenically unsaturated bond, such as a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadiimide group, or a (meth)acryloyl group, as a functional group exhibiting photopolymerizability. The (B) component is not particularly limited as long as it is a compound having one or more ethylenically unsaturated groups. As the functional group exhibiting photopolymerizability, a (meth)acryloyl group is preferred. The (B) component may be used alone or in combination of two or more.

Examples of photopolymerizable compounds having one ethylenically unsaturated group include (meth)acrylic acid, (meth)acrylic acid alkyl esters, and phthalic acid-based (meth)acrylate compounds.

Examples of (meth)acrylic acid alkyl esters include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, and (meth)acrylic acid hydroxylethyl ester.

Component (B) may contain a phthalic acid compound from the viewpoint of suitably improving resolution, adhesion, and resist shape. Examples of phthalic acid compounds include γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate (also known as 3-chloro-2-hydroxypropyl-2-(meth)acryloyloxyethyl phthalate), β-hydroxyethyl-β'-(meth)acryloyloxyethyl-o-phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate.

Examples of photopolymerizable compounds having two ethylenically unsaturated groups include polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis(4-(meth)acryloxypolyethoxypolypropoxyphenyl)propane, bisphenol A diglycidyl ether di(meth)acrylate, and alkylene oxide-modified bisphenol A di(meth)acrylate.

From the viewpoint of improving alkaline developability and resolution, component (B) may contain an alkylene oxide-modified bisphenol A di(meth)acrylate. Examples of alkylene oxide-modified bisphenol A di(meth)acrylate include 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane (2,2-bis(4-((meth)acryloxypentaethoxy)phenyl)propane, etc.), 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.

Examples of photopolymerizable compounds having three or more ethylenically unsaturated groups include (meth)acrylates having a skeleton derived from trimethylolpropane, such as trimethylolpropane tri(meth)acrylate; (meth)acrylates having a skeleton derived from tetramethylolmethane, such as tetramethylolmethane tri(meth)acrylate and tetramethylolmethane tetra(meth)acrylate; (meth)acrylates having a skeleton derived from pentaerythritol, such as pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate; (meth)acrylates having a skeleton derived from dipentaerythritol, such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate; (meth)acrylates having a skeleton derived from ditrimethylolpropane, such as ditrimethylolpropane tetra(meth)acrylate; and (meth)acrylates having a skeleton derived from diglycerin. Among these, from the viewpoint of increasing the chemical resistance after curing (exposure) and increasing the difference in developer resistance between exposed and unexposed areas, (meth)acrylate compounds having a skeleton derived from dipentaerythritol are preferred, and dipentaerythritol penta(meth)acrylate is more preferred.

From the viewpoint of improving the alkaline developability of the unexposed parts of the photosensitive resin composition and improving the adhesive strength of the exposed parts, component (B) may contain a photopolymerizable compound having an ethylenically unsaturated group and an acid-modified group. Examples of the acidic group to be modified include a carboxy group, a sulfo group, and a phenolic hydroxyl group, and among these, a carboxy group is preferred.

Examples of photopolymerizable compounds having an ethylenically unsaturated group and an acidic group include styrene-maleic acid resins and acid-modified vinyl group-containing epoxy derivatives.

Styrene-maleic acid resins are hydroxyethyl (meth)acrylate modified styrene-maleic anhydride copolymers. Acid-modified vinyl group-containing epoxy derivatives are compounds obtained by reacting a compound in which an epoxy resin is modified with a vinyl group-containing organic acid with a saturated or unsaturated group-containing polybasic acid anhydride.

The epoxy resin is not particularly limited as long as it is a compound having two or more epoxy groups. Examples of the epoxy resin include glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, and glycidyl ester type epoxy resins. Among these, from the viewpoint of reliability during semiconductor chip mounting, bisphenol novolac type epoxy resins are preferred, and bisphenol F novolac type epoxy resins are more preferred.

The vinyl group-containing organic acid is not particularly limited, and may be a vinyl group-containing monocarboxylic acid. Examples of vinyl group-containing monocarboxylic acids include acrylic acid, acrylic acid dimers, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, α-cyanocinnamic acid, and other acrylic acid derivatives; half-ester compounds which are reaction products of hydroxyl group-containing acrylates and dibasic acid anhydrides; and half-ester compounds which are reaction products of vinyl group-containing monoglycidyl ethers or vinyl group-containing monoglycidyl esters and dibasic acid anhydrides.

The ethylenically unsaturated bond is not particularly limited as long as it is photopolymerizable. Examples of the ethylenically unsaturated bond include α,β-unsaturated carbonyl groups such as (meth)acryloyl groups. Examples of photopolymerizable compounds having α,β-unsaturated carbonyl groups include α,β-unsaturated carboxylic acid esters of polyhydric alcohols, bisphenol-type (meth)acrylates, α,β-unsaturated carboxylic acid adducts of glycidyl group-containing compounds, (meth)acrylates having urethane bonds, nonylphenoxy polyethyleneoxy acrylates, and (meth)acrylic acid alkyl esters.

Examples of α,β-unsaturated carboxylic acid esters of polyhydric alcohols include polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups, polypropylene glycol di(meth)acrylate having 2 to 14 propylene groups, polyethylene-polypropylene glycol di(meth)acrylate having 2 to 14 ethylene groups and 2 to 14 propylene groups, 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, tetramethylolmethane tetra(meth)acrylate, and (meth)acrylate compounds having a skeleton derived from dipentaerythritol or pentaerythritol. "EO modified" means that it has a block structure of ethylene oxide (EO) groups, and "PO modified" means that it has a block structure of propylene oxide (PO) groups.

From the viewpoint of improving the flexibility of the resist pattern, the (B) component may contain a polyalkylene glycol di(meth)acrylate. The polyalkylene glycol di(meth)acrylate may have at least one of an EO group and a PO group, or may have both an EO group and a PO group. In a polyalkylene glycol di(meth)acrylate having both an EO group and a PO group, the EO group and the PO group may each be present in a continuous block form or may be present randomly. The PO group may be either an oxy-n-propylene group or an oxyisopropylene group. In the (poly)oxyisopropylene group, the secondary carbon of the propylene group may be bonded to an oxygen atom, and the primary carbon may be bonded to an oxygen atom.

Commercially available polyalkylene glycol di(meth)acrylates include, for example, FA-023M (manufactured by Hitachi Chemical Co., Ltd.), FA-024M (manufactured by Hitachi Chemical Co., Ltd.), and NK Ester HEMA-9P (manufactured by Shin-Nakamura Chemical Co., Ltd.).

From the viewpoint of improving the flexibility of the resist pattern, component (B) may contain a (meth)acrylate having a urethane bond. Examples of (meth)acrylates having a urethane bond include an addition reaction product of a (meth)acrylic monomer having an OH group at the β-position with a diisocyanate (isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, 1,6-hexamethylene diisocyanate, etc.), tris((meth)acryloxytetraethylene glycol isocyanate)hexamethylene isocyanurate, EO-modified urethane di(meth)acrylate, and EO,PO-modified urethane di(meth)acrylate.

Commercially available EO-modified urethane di(meth)acrylates include, for example, "UA-11" and "UA-21EB" (manufactured by Shin-Nakamura Chemical Co., Ltd.). Commercially available EO, PO-modified urethane di(meth)acrylates include, for example, "UA-13" (manufactured by Shin-Nakamura Chemical Co., Ltd.).

From the viewpoint of facilitating the formation of a thick resist pattern and improving resolution and adhesion in a well-balanced manner, component (B) may contain a (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol. The (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol preferably has four or more (meth)acryloyl groups, and may be dipentaerythritol penta(meth)acrylate or dipentaerythritol hexa(meth)acrylate.

From the viewpoint of further improving the resolution and release properties after curing, component (B) may contain a bisphenol type (meth)acrylate, and among the bisphenol type (meth)acrylates, it may contain a bisphenol A type (meth)acrylate. 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. Among them, from the viewpoint of further improving the resolution and pattern formability, 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is preferred.

Commercially available products include, for example, 2,2-bis(4-((meth)acryloxydipropoxy)phenyl)propane, BPE-200 (Shin-Nakamura Chemical Co., Ltd.), 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane, BPE-500 (Shin-Nakamura Chemical Co., Ltd.), and FA-321M (Hitachi Chemical Co., Ltd.).

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

<(C) Photopolymerization initiator>
The component (C) is not particularly limited as long as it is a component that can polymerize the component (B), and can be appropriately selected from commonly used photopolymerization initiators. The component (C) can be used alone or in combination of two or more.

Examples of component (C) include photopolymerization initiators such as acylphosphine oxides, oxime esters, aromatic ketones, quinones, alkylphenones, imidazoles, acridines, phenylglycines, and coumarins.

Component (C) may contain an acridine-based photopolymerization initiator, a phenylglycine-based photopolymerization initiator, or an imidazole-based photopolymerization initiator in order to improve sensitivity and resolution in a well-balanced manner.

Examples of acridine-based photopolymerization initiators include 9-phenylacridine, 9-(p-methylphenyl)acridine, 9-(m-methylphenyl)acridine, 9-(p-chlorophenyl)acridine, 9-(m-chlorophenyl)acridine, 9-aminoacridine, 9-dimethylaminoacridine, 9-diethylaminoacridine, 9-pentylaminoacridine, 1,2-bis(9-acridinyl)ethane, 1,4-bis(9-acridinyl)butane, 1,6-bis(9-acridinyl)hexane, and 1,8-bis(9-acridinyl)octaacridine. bis(9-acridinyl)alkanes such as 1,10-bis(9-acridinyl)decane, 1,12-bis(9-acridinyl)dodecane, 1,14-bis(9-acridinyl)tetradecane, 1,16-bis(9-acridinyl)hexadecane, 1,18-bis(9-acridinyl)octadecane, and 1,20-bis(9-acridinyl)eicosane; 1,3-bis(9-acridinyl)-2-oxapropane, 1,3-bis(9-acridinyl)-2-thiapropane, and 1,5-bis(9-acridinyl)-3-thiapentane.

Examples of phenylglycine-based photopolymerization initiators include N-phenylglycine, N-methyl-N-phenylglycine, and N-ethyl-N-phenylglycine.

Examples of imidazole-based photopolymerization initiators include 2-(o-chlorophenyl)-4,5-diphenylbiimidazole, 2,2',5-tris-(o-chlorophenyl)-4-(3,4-dimethoxyphenyl)-4',5'-diphenylbiimidazole, 2,4-bis-(o-chlorophenyl)-5-(3,4-dimethoxyphenyl)-diphenylbiimidazole, 2,4,5-tris-(o-chlorophenyl)-diphenylbiimidazole, 2-(o-chlorophenyl)-bis-4,5-(3,4-dimethoxyphenyl)-biimidazole, 2,2'- These include bis-(2-fluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3-difluoromethylphenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,4-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, and 2,2'-bis-(2,5-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole.

The content of component (C) may be 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, or 0.5 to 4 parts by mass, based on 100 parts by mass of the total amount of components (A) and (B). When the content of component (C) is 0.1 parts by mass or more, the photosensitivity, resolution, and adhesion tend to be improved, and when it is 10 parts by mass or less, the resist pattern formability tends to be better.

<Component (D): Photosensitizer>
The photosensitive resin composition according to the present embodiment may further contain a photosensitizer as component (D). By containing component (D), it is possible to effectively utilize the absorption wavelength of the actinic ray used for exposure. The component (D) may be used alone or in combination of two or more.

Component (D) may, for example, be a dialkylaminobenzophenone compound, a pyrazoline compound, an anthracene compound, a coumarin compound, a xanthone compound, a thioxanthone compound, an oxazole compound, a benzoxazole compound, a thiazole compound, a benzothiazole compound, a triazole compound, a stilbene compound, a triazine compound, a thiophene compound, a naphthalimide compound, a triarylamine compound, or an aminoacridine compound. Component (D) may contain a pyrazoline compound or an anthracene compound in order to further improve resolution.

Examples of pyrazoline compounds include 1-(4-methoxyphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1,5-bis-(4-methoxyphenyl)-3-(4-methoxystyryl)-pyrazoline, 1-(4-isopropylphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, and 1,5-bis-(4-isopropylphenyl)-3-(4-isopropyl propylstyryl)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-isopropyl-styryl)-5-(4-isopropyl-phenyl) 1-(4-methoxyphenyl)-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-phenyl-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,6-dimethoxystyryl)-5-(2,6- dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,4-dimethoxystyryl) 1-(4-methoxyphenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl) -pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)- Pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline , 1-(4-isopropyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, and 1-(4-isopropyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline.

Examples of anthracene compounds include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, and 9,10-dipentoxyanthracene.

From the viewpoint of improving photosensitivity and resolution, the content of component (D) may be 0.01 to 5 parts by mass, 0.01 to 1 part by mass, or 0.01 to 0.2 parts by mass per 100 parts by mass of the total amount of components (A) and (B).

(Other ingredients)
The photosensitive resin composition according to the present embodiment may further contain additives such as dyes, photocoloring agents, thermal coloring inhibitors, plasticizers, pigments, fillers, defoamers, flame retardants, adhesion imparting agents, leveling agents, peeling promoters, antioxidants, fragrances, imaging agents, thermal crosslinking agents, polymerization inhibitors, etc. These additives may be used alone or in combination of two or more.

Dyes include, for example, malachite green, Victoria Pure Blue, brilliant green, and methyl violet. Photochromic agents include, for example, tribromophenyl sulfone, leuco crystal violet, diphenylamine, benzylamine, triphenylamine, diethylaniline, and o-chloroaniline. Plasticizers include, for example, p-toluenesulfonamide.

The photosensitive resin composition can be prepared as necessary by dissolving it in a solvent such as methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, propylene glycol monomethyl ether, or a mixture of these solvents, to form a solution with a solids content of about 30 to 60% by mass.

[Photosensitive element]
The photosensitive element of this embodiment includes a support and a photosensitive layer formed on the support, and the photosensitive layer includes the above-mentioned photosensitive resin composition. When using the photosensitive element of this embodiment, the photosensitive layer may be laminated on a substrate and then exposed without peeling off the support (support film). As shown in the schematic cross-sectional view of an example in FIG. 1, the photosensitive element 1 according to this embodiment includes a support 2 and a photosensitive layer 3 derived from the above-mentioned photosensitive resin composition formed on the support 2, and is configured to include other layers such as a protective layer 4 that are provided as necessary.

(Support)
Examples of the support include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene-2,6-naphthalate (PEN), and polyolefin films such as polypropylene and polyethylene. Among these, a PET film may be used because it is easily available and has excellent handleability (particularly heat resistance, heat shrinkage rate, and breaking strength) in the production process.

The haze of the support may be 0.01 to 1.0% or 0.01 to 0.5%. If the haze is 0.01% or more, the support itself tends to be easier to manufacture, and if it is 1.0% or less, micro-defects that may occur in the resist pattern tend to be reduced. "Haze" means cloudiness. In this disclosure, the haze refers to a value measured using a commercially available haze meter (turbidity meter) in accordance with the method specified in JIS K 7105. Haze can be measured, for example, using a commercially available turbidity meter such as NDH-5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

The thickness of the support may be 1 to 100 μm, 5 to 60 μm, 10 to 50 μm, 10 to 40 μm, 10 to 30 μm, or 10 to 25 μm. When the thickness of the support is 1 μm or more, it tends to be possible to prevent the support from breaking when peeling it off. Furthermore, when the thickness of the support is 100 μm or less, it is possible to prevent a decrease in resolution when exposure is performed through the support.

(Protective Layer)
The photosensitive element may further include a protective layer, if necessary. As the protective layer, a film may be used in which the adhesive strength between the photosensitive layer and the protective layer is smaller than the adhesive strength between the photosensitive layer and the support, or a film with low fisheyes may be used. Specific examples include those that can be used as the support described above. From the viewpoint of peelability from the photosensitive layer, a polyethylene film may be used. The thickness of the protective layer may be about 1 to 100 μm, depending on the application.

The photosensitive element can be manufactured, for example, as follows. That is, a solution (coating liquid) of the photosensitive resin composition is applied onto a support to form a coating layer, which is then dried to form a photosensitive layer. Next, the surface of the photosensitive layer opposite the support is covered with a protective layer to obtain a photosensitive element comprising the support, the photosensitive layer formed on the support, and the protective layer laminated on the photosensitive layer.

The coating solution can be applied to the support by known methods such as roll coating, comma coating, gravure coating, air knife coating, die coating, and bar coating.

There are no particular limitations on the drying of the coating layer, so long as at least a portion of the organic solvent can be removed from the coating layer. For example, drying may be performed at 70 to 150°C for about 5 to 30 minutes. After drying, the amount of solvent remaining in the photosensitive layer may be 2% by mass or less, from the viewpoint of preventing diffusion of the solvent in subsequent steps.

The thickness of the photosensitive layer in the photosensitive element can be appropriately selected depending on the application, but may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm after drying. A thickness of 1 μm or more facilitates industrial coating and improves productivity. A thickness of 100 μm or less improves adhesion and resolution.

The form of the photosensitive element is not particularly limited. For example, it may be in the form of a sheet, or may be wound into a roll around a core. When wound into a roll, it may be wound so that the support film is on the outside. Examples of the core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer).

An end separator may be installed on the end surface of the rolled photosensitive element to protect the end surface, and a moisture-proof end separator may be installed to prevent edge fusion. The photosensitive element may be wrapped in a black sheet with low moisture permeability.

The photosensitive element can be suitably used, for example, in the resist pattern forming method described below. In particular, from the viewpoint of resolution, it is suitable for application to a manufacturing method in which a conductor pattern is formed by plating processing.

[Method of forming a resist pattern]
The method for forming a resist pattern of this embodiment includes (i) a step of forming a photosensitive layer on a substrate using the photosensitive resin composition or the photosensitive element (photosensitive layer forming step), (ii) a step of irradiating at least a part (predetermined part) of the photosensitive layer with active light rays to form a photocured part (exposure step), and (iii) a step of removing at least a part of the substrate other than the photocured part to form a resist pattern (development step), and may include other steps as necessary. The resist pattern may be a photocured product pattern of the photosensitive resin composition or a relief pattern. The method for forming a resist pattern may be a method for producing a substrate with a resist pattern.

(i) Photosensitive layer forming step)
The method of forming the photosensitive layer on the substrate may be, for example, coating and drying the photosensitive resin composition, or removing the protective layer from the photosensitive element, and then pressing the photosensitive layer of the photosensitive element onto the substrate while heating. When the photosensitive element is used, a laminate consisting of a substrate, a photosensitive layer, and a support, which are laminated in order, is obtained. The substrate is not particularly limited, but is usually a circuit-forming substrate having an insulating layer and a conductor layer formed on the insulating layer, or a die pad (substrate for lead frame) such as an alloy substrate.

When a photosensitive element is used, the photosensitive layer forming step is preferably carried out under reduced pressure from the viewpoint of adhesion and followability. The photosensitive layer and/or the substrate may be heated at a temperature of 70 to 130° C. during pressure bonding. The pressure bonding may be carried out at a pressure of about 0.1 to 1.0 MPa (about 1 to 10 kgf/cm ² ), and these conditions are appropriately selected as necessary. If the photosensitive layer is heated to 70 to 130° C., it is not necessary to preheat the substrate in advance, but the substrate may be preheated in order to further improve adhesion and followability.

((ii) Exposure Step)
In the exposure step, at least a part of the photosensitive layer formed on the substrate is irradiated with active light rays, whereby the part irradiated with the active light rays is photocured to form a latent image. In this case, if a support is present on the photosensitive layer, and if the support is transparent to the active light rays, the active light rays can be irradiated through the support, but if the support is light-shielding, the support is removed before the photosensitive layer is irradiated with the active light rays.

Examples of the exposure method include a method of irradiating an active light beam in an image-wise manner through a negative or positive mask pattern called artwork (mask exposure method). A method of irradiating an active light beam in an image-wise manner by a projection exposure method may also be used. A method of irradiating an active light beam in an image-wise manner by a direct imaging exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may also be used.

The light source for the actinic rays can be any known light source, including, for example, carbon arc lamps, mercury vapor arc lamps, high pressure mercury lamps, xenon lamps, gas lasers such as argon lasers, solid-state lasers such as YAG lasers, and semiconductor lasers that effectively emit ultraviolet light and visible light.

((iii) Development Step)
In the developing step, at least a portion of the photosensitive layer other than the photocured portion is removed from the substrate, thereby forming a resist pattern on the substrate.

If a support is present on the photosensitive layer, the support is removed before removing (developing) the areas other than the photocured areas (also called the unexposed areas). There are two development methods: wet development and dry development, with wet development being more widely used.

In the case of wet development, a developer suitable for the photosensitive resin composition is used, and development is performed by a known development method. Examples of development methods include a dip method, a paddle method, a spray method, brushing, slapping, scrubbing, and rocking immersion, and from the viewpoint of improving resolution, a high-pressure spray method may be used. Development may be performed by combining two or more of these methods.

The composition of the developer is appropriately selected depending on the composition of the photosensitive resin composition. Examples of the developer include an alkaline aqueous solution and an organic solvent developer.

From the viewpoint of safety, stability, and good operability, an alkaline aqueous solution may be used as the developer. Examples of bases for the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide; alkali carbonates such as lithium, sodium, potassium, or ammonium carbonates or bicarbonates; alkali metal phosphates such as potassium phosphate and sodium phosphate; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol, 1,3-diaminopropanol-2, and morpholine.

The alkaline aqueous solution used for development may be 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, or a dilute solution of 0.1 to 5% by mass sodium tetraborate. The pH of the alkaline aqueous solution may be in the range of 9 to 14, and the temperature can be adjusted according to the alkaline developability of the photosensitive layer. For example, a surfactant, an antifoaming agent, or a small amount of an organic solvent to promote development may be mixed into the alkaline aqueous solution.

Examples of organic solvents that can be used in alkaline aqueous solutions include acetone, ethyl acetate, alkoxyethanols with 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.

Examples of organic solvents used in the organic solvent developer include 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. To prevent ignition, water may be added to these organic solvents in a range of 1 to 20% by weight to form an organic solvent developer.

The method for forming a resist pattern in this embodiment may include a step of further curing the resist pattern by heating at about 60 to 250° C. or exposing to light at about 0.2 to 10 J/cm ² , as necessary, after removing the uncured portions in the development step.

[Method of forming wiring pattern]
The method for forming a wiring pattern according to the present 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 method for forming a resist pattern described above. The method for forming a wiring pattern may further include a step of removing the photocured portion with an alkaline aqueous solution after the etching or plating.

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

On the other hand, in the etching process, the conductor layer on the substrate is etched away using a resist pattern formed on the substrate as a mask to form a conductor pattern. The etching method is appropriately selected depending on the conductor layer to be removed. Examples of etching solutions include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide-based etching solution.

After the etching or plating process, the resist pattern on the substrate may be removed. The resist pattern may be removed, for example, by using an aqueous solution that is more strongly alkaline than the aqueous solution used in the development process. Examples of the strongly alkaline aqueous solution include an aqueous solution of 1 to 10% by mass of sodium hydroxide and an aqueous solution of 1 to 10% by mass of potassium hydroxide. The resist pattern may be removed using a strong aqueous solution at 45 to 65°C.

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

The method for forming a wiring pattern according to this embodiment can be applied to the manufacture of not only single-layer printed wiring boards, but also multi-layer printed wiring boards, and can also be applied to the manufacture of printed wiring boards with small-diameter through holes.

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

(1) Trityl methacrylate (MA-Tr)
150 mL of petroleum ether, 0.10 mol of triphenylmethyl, 0.11 mol of methacrylic acid, and 0.10 mol of triethylamine were added to a 1000 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser tube, and the reaction was carried out at room temperature for 6 hours. After removing triethylamine hydrochloride produced as a product from the reaction solution, the reaction solution was washed three times by adding 100 mL of a 3% by mass aqueous solution of sodium carbonate. After drying the reaction solution after washing with magnesium sulfate, the solvent was removed by vacuum drying to obtain MA-Tr. The yield was 90%.

(2) tert-Butyldimethylsilyl methacrylate (MA-TBDMS)
150 mL of dichloromethane, 0.20 mol of methacrylic acid, and 0.22 mol of triethylamine were added to a 500 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, and the mixture was stirred for 10 minutes. Then, 0.21 mmol of tert-butyldimethylsilyl chloride was added dropwise to the flask, and the reaction was carried out at room temperature for 24 hours. The reaction solution was washed twice with a 3% aqueous hydrochloric acid solution, and then washed three times with pure water. After the reaction solution was washed, it was dried over magnesium sulfate, and the solvent was removed by vacuum drying to obtain MA-TBDMS. The yield was 98%.

(3) Triethylsilyl methacrylate (MA-TES)
150 mL of dichloromethane, 0.20 mol of methacrylic acid, and 0.22 mol of triethylamine were added to a 500 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, and a reflux condenser, and the mixture was stirred for 10 minutes. Next, 0.21 mmol of triethylsilyl chloride was added dropwise to the flask, and the reaction was carried out at room temperature for 24 hours. The reaction solution was washed twice with a 3% aqueous hydrochloric acid solution, and then washed three times with pure water. After the reaction solution was washed, it was dried over magnesium sulfate, and the solvent was removed by vacuum drying to obtain MA-TES. The yield was 90%.

(4) Alkali-soluble resin (Example 1)
A 1000 mL three-neck flask equipped with a stirrer, a nitrogen inlet tube, a reflux condenser, a dropping funnel and a thermometer was charged with 96 g of propylene glycol monomethyl ether (MFG) and 64 g of toluene, and the temperature was raised to 80 ° C. under a nitrogen atmosphere. A mixture of 20 g of methacrylic acid (MA), 30 g of styrene (STC), 40 g of benzyl methacrylate (BzMA), 10 g of trimethylsilyl methacrylate (MA-TMS), and 1 g of azobisisobutyronitrile (AIBN) was dropped into the flask over 3 hours, and then a mixture of 6 g of MFG, 4 g of toluene, and 0.20 g of AIBN was dropped over 2 hours, and further 6 g of MFG and 4 g of toluene were dropped to carry out the reaction. The reaction liquid was heated to 95 ° C. and stirred for 1.5 hours, and then cooled to room temperature to obtain a polymer solution of alkali-soluble resin (A1). The non-volatile content (solid content) of the polymer solution was 40% by mass.

(Examples 2 to 4)
Polymer solutions of alkali-soluble resins (A2) to (A4) were obtained in the same manner as in Example 1, except that MA, STC, BzMA, and MA-TMS were used in the amounts shown in Table 1.

(Examples 5 to 8)
Polymer solutions of alkali-soluble resins (A5) to (A8) were obtained in the same manner as in Example 1, except that MA, STC, BzMA, and MA-Tr were used in the amounts shown in Table 1.

Example 9
A polymer solution of an alkali-soluble resin (A9) was obtained in the same manner as in Example 1, except that MA, STC, BzMA, and 2-(trimethylsilyloxy)ethyl methacrylate (HEMA-TMS) were used in the amounts shown in Table 1.

(Examples 10 to 12)
Polymer solutions of alkali-soluble resins (A10) to (A12) were obtained in the same manner as in Example 1, except that MA, methyl methacrylate (MMA), STC, BzMA, and HEMA-TMS were used in the amounts shown in Table 1.

(Example 13)
A polymer solution of an alkali-soluble resin (A13) was obtained in the same manner as in Example 1, except that MA, STC, BzMA, and MA-TBDMS were used in the amounts shown in Table 1.

(Example 14)
A polymer solution of an alkali-soluble resin (A14) was obtained in the same manner as in Example 1, except that MA, STC, BzMA, and MA-TES were used in the amounts shown in Table 1.

(Comparative Example 1)
A polymer solution of an alkali-soluble resin (B1) was obtained in the same manner as in Example 1, except that MA, STC, and BzMA were used in the amounts shown in Table 1.

(Comparative Examples 2 to 3)
Polymer solutions of alkali-soluble resins (B2) and (B3) were obtained in the same manner as in Example 1, except that MA, MMA, STC, and BzMA were used in the amounts shown in Table 1.

(Weight average molecular weight)
120 mg of the polymer solution was taken and dissolved in 5 mL of THF to prepare a sample for Mw measurement. Mw was measured by gel permeation chromatography (GPC) and calculated using a calibration curve of standard polystyrene. The GPC conditions are shown below.

(GPC conditions)
Pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd.)
Columns: Gelpack GL-R420, Gelpack GL-R430, and Gelpack GL-R440 (manufactured by Hitachi Chemical Co., Ltd., column specifications: 10.7 mmφ×300 mm)
Eluent: tetrahydrofuran (THF)
Measurement temperature: 40°C
Injection volume: 200 μL
Pressure: 49 kgf/ ^cm2 (4.8 MPa)
Flow rate: 2.05 mL/min. Detector: Hitachi L-3300 RI (manufactured by Hitachi, Ltd.)

(5) Photosensitive Resin Composition A photosensitive resin composition was prepared by mixing each component in the blending amount (parts by mass) shown in Table 2 with 140 parts by mass of the above polymer solution (alkali-soluble resin: 56 parts by mass).

Details of each component shown in Table 2 are as follows.
(Photopolymerizable Compound)
FA-321M (product name): 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (manufactured by Hitachi Chemical Co., Ltd.)
FA-023M (product name): Polyalkylene glycol di(meth)acrylate (manufactured by Hitachi Chemical Co., Ltd.)
FA-MECH (trade name): (2-hydroxy-3-chloro)propyl-2-methacryloyloxyethyl phthalate (manufactured by Hitachi Chemical Co., Ltd.)
(Photopolymerization initiator)
BCIM (trade name): 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Hampford)
(Sensitizer)
DBA (product name): 9,10-dibutoxyanthracene (Kawasaki Chemical Industries, Ltd.)
(Photochromic Agent)
LCV: Leuco Crystal Violet (Yamada Chemical Industry Co., Ltd.)
(Adhesion imparting agent)
SF-808H: A mixture of carboxybenzotriazole, 5-amino-1H-tetrazole and methoxypropanol (Sanwa Chemical Co., Ltd.)
(dye)
MKG: Malachite Green (Osaka Organic Chemical Industry Ltd.)

(6) Photosensitive element The photosensitive resin composition was applied onto a 16 μm-thick polyethylene terephthalate (PET) film (Teijin Film Solutions Limited, product name "G2J") (support), and dried in succession in hot air convection dryers at 75° C. and 125° C. to form a photosensitive layer having a thickness of 25 μm after drying. A polypropylene film (Tamapoly Corporation, product name "NF-13") (protective layer) was laminated onto this photosensitive layer, to obtain a photosensitive element in which the support, photosensitive layer, and protective layer were laminated in this order.

[evaluation]
(Hydrophilicity)
After 7 g of monomer was put into a 20 mL glass bottle, ion-exchanged water was added and the bottle was left to stand at 23° C. for 12 hours, and then only the monomer was collected with a syringe and the amount of water contained in the monomer was determined by the Karl Fischer method. The amount of water (mass%) contained in the monomer was taken as the hydrophilicity of the monomer. The hydrophilicity of each monomer is shown in Table 3.

The initial hydrophilicity of the alkali-soluble resin, the hydrophilicity after polarity conversion, and the rate of increase in hydrophilicity were calculated from the hydrophilicity of the monomers and the copolymerization ratio of the monomers. The hydrophilicity of the alkali-soluble resins of the examples is shown in Table 4, and the hydrophilicity of the alkali-soluble resins of the comparative examples is shown in Table 5.

(Laminate)
A copper-clad laminate (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-67") in which copper foil (thickness: 35 μm) was laminated on both sides of a glass fiber reinforced epoxy resin layer was washed with water, pickled, and washed with water, and then dried with an air flow. The copper-clad laminate was then heated to 80° C., and a photosensitive element was laminated on the copper surface of the copper-clad laminate. The lamination was performed using a heat roll at 110° C., with a pressure of 0.4 MPa for the substrate and a roll speed of 1.0 m/min, while removing the protective layer. In this way, a laminate in which the copper-clad laminate, the photosensitive layer, and the support were laminated in this order was obtained.

(Developability)
After laminating a photosensitive layer with a thickness of 25 μm on a substrate, the photosensitive layer was developed with a 1% by mass aqueous solution of sodium carbonate at 30° C., and the development time until the residual film became zero was measured. A development time of 20 seconds or less was evaluated as “A”, and a development time of less than 20 seconds was evaluated as “B”.

(Resolution)
A glass chrome type phototool (resolution negative: having a wiring pattern with a line width/space width of x/x (x: 1 to 30, unit: μm)) was used as a negative for evaluating resolution on the support of the laminate, and exposure was performed with an energy amount that resulted in a remaining step number of 17.0 after development on a Hitachi 41-step step tablet. After exposure, the photosensitive layer was developed in the same manner as in the evaluation of photosensitivity.

After development, the space areas (unexposed areas) were completely removed, and the line areas (exposed areas) were formed without meandering or chipping. Among the resist patterns, the resolution was evaluated based on the smallest space width. If the smallest space width was less than 15 μm, it was rated as "A", if it was 15 to 20 μm, it was rated as "B", and if it was more than 20 μm, it was rated as "C".

(Peeling properties)
A laminate in which a photosensitive layer having a thickness of 25 μm was laminated on a substrate was irradiated with 30 mJ at 405 nm using a direct imaging exposure machine, and then a 1% by mass aqueous solution of sodium carbonate at 30° C. was spray-developed for twice the minimum development time (the shortest time required for the unexposed portion to be removed) to remove the unexposed portion (development treatment). After the development treatment, a test piece was obtained in which a 40 mm×50 mm cured film was formed on the substrate. The test piece was immersed in a 3% by mass aqueous solution of sodium hydroxide at 50° C., and the time until the cured film peeled off from the substrate was measured. The peeling time was rated as “A” when it was less than 50 seconds, “B” when it was 50 seconds or more but less than 60 seconds, and “C” when it was 60 seconds or more.

These results confirm that a photosensitive resin composition containing an alkali-soluble resin that includes a structural unit having a polarity conversion group can achieve both developability, resolution, and peelability.

1...photosensitive element, 2...support, 3...photosensitive layer, 4...protective layer.

Claims (8)

The polymer contains a structural unit having a polarity conversion group, a structural unit having a carboxy group, and a structural unit based on a benzyl (meth)acrylate ester,
An alkali-soluble resin, wherein the polarity conversion group has a group that does not leave under weak alkaline conditions but leaves under strong alkaline conditions, and is a group represented by the following formula (1) (excluding polymers having (a) a terpenoid skeleton or an alicyclic skeleton and (b) a substituted or unsubstituted silyl group structure):

[In formula (1), ^R2 represents a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, or a trityl group.] 2. The alkali-soluble resin according to claim 1, wherein the structural unit having a polarity conversion group is a structural unit based on a compound represented by the following formula (2):

[In formula (2), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents an alkylene group having 1 to 6 carbon atoms, and R ² represents a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, or a trityl group.] The alkali-soluble resin according to claim 1 or 2, wherein R ² is a trityl group. A photosensitive resin composition comprising a binder resin containing the alkali-soluble resin according to any one of claims 1 to 3, a photopolymerizable compound, and a photopolymerization initiator. A support and a photosensitive layer formed on the support,
A photosensitive element, wherein the photosensitive layer comprises the photosensitive resin composition of claim 4 . forming a photosensitive layer on a substrate using the photosensitive resin composition according to claim 4 or the photosensitive element according to claim 5;
a step of irradiating at least a portion of the photosensitive layer with active light rays to form a photocured portion;
removing at least a portion of the photosensitive layer other than the photocured portion from the substrate to form a resist pattern;
A method for forming a resist pattern comprising: A method for forming a wiring pattern, comprising a step of forming a conductor pattern by 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. 8. The method for forming a wiring pattern according to claim 7, further comprising the step of removing the photocured portion with an alkaline aqueous solution after the etching treatment or the plating treatment.

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