JP2024118288A - Photosensitive resin composition - Google Patents

Abstract

To provide a photosensitive resin composition from which a cured product having critical resolution and a wide process window can be obtained.SOLUTION: A photosensitive resin composition contains (A) a polyimide precursor, (B) a radical generator, (C) a tetra- or lower-functional photo-crosslinking agent, and (D) a penta- or higher-functional photo-crosslinking agent.SELECTED DRAWING: None

Description

The present invention relates to a photosensitive resin composition. It also relates to a photosensitive film, a semiconductor package substrate, and a semiconductor device obtained using the photosensitive resin composition.

Traditionally, polyimide resins, which have excellent heat resistance and insulating properties, have been used for the insulating layers of semiconductor devices. In general, polyimide resins have low solubility in solvents, so in photosensitive resin compositions, they are used in the form of a polyimide precursor, and after forming an insulating layer, the polyimide precursor is cyclized to form an insulating layer (see, for example, Patent Document 1).

JP 2003-084435 A

In recent years, with the increase in communication speed and capacity in communication devices, there is a demand for higher density wiring in the semiconductor package substrate of the communication device. From the viewpoint of responding to the higher density wiring, it is desirable for the photosensitive resin composition used in the semiconductor package substrate to have excellent limiting resolution. Furthermore, from the viewpoint of ease of manufacturing the semiconductor package, it is desirable for the photosensitive resin composition used in the semiconductor package substrate to have a wide process window of exposure amount when exposing the photosensitive resin composition.

The limiting resolution refers to the limit of how small an opening can be formed in a photosensitive resin composition by exposure and development, and the smaller the better. The process window refers to the range in which the shape of the opening that can be formed in the photosensitive resin composition does not change even if the exposure dose varies from the optimal value, or is within an acceptable range.

The present invention has been made in consideration of the above problems, and aims to provide a photosensitive resin composition capable of producing a cured product with a wide limiting resolution and process window, and a photosensitive film and a semiconductor package substrate obtained using the photosensitive resin composition.

As a result of intensive research, the inventors discovered that the above object can be achieved by incorporating a combination of a polyimide precursor, a radical generator, a photocrosslinking agent having 4 or less functionalities, and a photocrosslinking agent having 5 or more functionalities in a photosensitive resin composition, and thus completed the present invention.

（式中、Ａはそれぞれ独立に４価の有機基を表し、Ｂはそれぞれ独立にインダン骨格を有する２価の有機基を表し、Ｒ^１及びＲ^２はそれぞれ独立に、水素原子又は１価の有機基を表す。ｎは５～２００の整数を表す。）
［５］ （Ａ）成分が、下記式（Ａ－３）で表される構造単位を有する、［１］～［４］のいずれかに記載の感光性樹脂組成物。

（式中、Ａ１はそれぞれ独立に４価の有機基を表し、Ｒ^１１及びＲ^１２はそれぞれ独立に、水素原子又は１価の有機基を表し、Ｒ^１３はそれぞれ独立に、水素原子又はメチル基を表し、Ｘａはそれぞれ独立に、単結合、下記式（１）で表される基、又は式（２）で表される基を表し、Ｘｂはそれぞれ独立に、単結合、式（３）で表される基、又は式（４）で表される基を表す。ｍ１は１～５の整数を表し、ｎ１は５～２００の整数を表す。）

（式（１）～（４）中、＊は結合手を表す。）
［６］ 式（Ａ－１）中のＲ^１及びＲ^２は、それぞれ独立に水素原子又は下式（Ａ－２）で表されるラジカル反応性基を表す、［４］又は［５］に記載の感光性樹脂組成物。

（式中、Ｒ^４～Ｒ^６は、それぞれ独立に、水素原子又は炭素原子数１～３の脂肪族炭化水素基を表し、ｐは１～１０の整数を表す。）
［７］ 支持体と、支持体上に形成された［１］～［６］のいずれかに記載の感光性樹脂組成物からなる感光性樹脂組成物層とを含む、感光性フィルム。
［８］ ［１］～［６］のいずれかに記載の感光性樹脂組成物の硬化物により形成された絶縁層を含む半導体パッケージ基板。
［９］ ［８］に記載の半導体パッケージ基板を含む、半導体装置。 That is, the present invention includes the following.
[1] (A) a polyimide precursor,
(B) a radical generator,
A photosensitive resin composition comprising: (C) a tetrafunctional or lower crosslinking agent; and (D) a pentafunctional or higher crosslinking agent.
[2] The photosensitive resin composition according to [1], wherein C1 is the number of functional groups per molecule of the component (C) and D1 is the number of functional groups per molecule of the component (D), and C1/D1 is 0.1 or more and 0.8 or less.
[3] The photosensitive resin composition according to [1] or [2], wherein Cw is the content of the component (C) when the nonvolatile components of the photosensitive resin composition are taken as 100% by mass, and Dw is the content of the component (D) when the nonvolatile components of the photosensitive resin composition are taken as 100% by mass, and Cw/Dw is 0.1 or more and 5 or less.
[4] The photosensitive resin composition according to any one of [1] to [3], wherein the component (A) has a structural unit represented by the following formula (A-1):

(In the formula, each A independently represents a tetravalent organic group, each B independently represents a divalent organic group having an indane skeleton, ^R1 and ^R2 independently represent a hydrogen atom or a monovalent organic group, and n represents an integer of 5 to 200.)
[5] The photosensitive resin composition according to any one of [1] to [4], wherein the component (A) has a structural unit represented by the following formula (A-3):

(In the formula, A1 each independently represents a tetravalent organic group, R ¹¹ and R ¹² each independently represent a hydrogen atom or a monovalent organic group, R ¹³ each independently represent a hydrogen atom or a methyl group, Xa each independently represent a single bond, a group represented by the following formula (1) or a group represented by formula (2), and Xb each independently represent a single bond, a group represented by formula (3) or a group represented by formula (4). m1 represents an integer of 1 to 5, and n1 represents an integer of 5 to 200.)

(In formulas (1) to (4), * represents a bond.)
[6] The photosensitive resin composition according to [4] or [5], wherein R ¹ and R ² in formula (A-1) each independently represent a hydrogen atom or a radical reactive group represented by the following formula (A-2):

(In the formula, R ⁴ to R ⁶ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and p represents an integer of 1 to 10.)
[7] A photosensitive film comprising a support and a photosensitive resin composition layer formed on the support and comprising the photosensitive resin composition according to any one of [1] to [6].
[8] A semiconductor package substrate comprising an insulating layer formed from a cured product of the photosensitive resin composition according to any one of [1] to [6].
[9] A semiconductor device comprising the semiconductor package substrate according to [8].

The present invention provides a photosensitive film, a semiconductor package substrate, and a semiconductor device obtained using the photosensitive resin composition, which can produce a cured product with a wide limiting resolution and process window.

The photosensitive resin composition, photosensitive film, semiconductor package substrate, and semiconductor device of the present invention are described in detail below.

[Photosensitive resin composition]
The photosensitive resin composition of the present invention contains (A) a polyimide precursor, (B) a photoradical generator, (C) a tetrafunctional or lower photocrosslinking agent, and (D) a pentafunctional or higher photocrosslinking agent. By incorporating the components (A) to (D) in combination in the photosensitive resin composition, a cured product having a wide limit resolution and process window can be obtained. It is also possible to obtain a cured product having excellent undercut resistance. The photosensitive resin composition of the present invention is suitable as a negative type photosensitive resin composition.

In general, when a photosensitive resin composition is exposed to light and developed to form a hole, the diameter of the hole may become larger the further back the hole is (i.e., the further away from the exposed surface). Thus, in a cross section of the photosensitive resin composition cut along a plane in the thickness direction, the cross-sectional shape of the hole may be an inverted taper shape in which the diameter of the bottom formed at the deepest part is larger than the diameter of the opening formed on the exposed surface. In this case, the difference between the radius of the opening corresponding to the top of the hole and the radius of the bottom corresponding to the deepest part of the hole (bottom radius - top radius) is called "undercut". The closer to zero the undercut is, the better. The property of making the undercut smaller is sometimes called "undercut resistance".

<(A) Polyimide Precursor>
The photosensitive resin composition contains a polyimide precursor (A) as the component (A). The polyimide precursor (A) can be cyclically closed by heating to form a polyimide. Therefore, according to the cured product obtained by thermally curing the photosensitive resin composition containing the polyimide precursor (A), a good insulating layer can be formed by utilizing the excellent physical properties of the polyimide, and the limit resolution of the photosensitive resin composition can be improved. The component (A) may be used alone or in combination of two or more.

(A) As the polyimide precursor, a resin containing a plurality of one or more structural units selected from the group consisting of amic acid structural units and amic acid ester structural units can be used. The amic acid structural unit generally refers to a structural unit having a structure obtained by reacting a tetracarboxylic dianhydride with a diamine compound. The amic acid ester structural unit generally refers to a structural unit having a structure obtained by esterifying a part or all of the carboxy groups of an amic acid obtained by reacting a tetracarboxylic dianhydride with a diamine compound.

The polyimide precursor (A) preferably contains an indane skeleton. When a polyimide precursor (A) containing an indane skeleton is used, the limiting resolution of the photosensitive resin composition can be particularly good. In addition, according to the inventor's research, it has been found that photosensitive resin compositions containing a polyimide precursor (A) containing an indane skeleton generally have a narrow process window. However, in the present invention, by using a combination of a photocrosslinking agent (C) having 4 or less functionalities and a photocrosslinking agent (D) having 5 or more functionalities, it has been achieved to widen the process window even when using a polyimide precursor (A) containing an indane skeleton.

The (A) component preferably has an indane skeleton and is a resin having multiple amic acid and/or amic acid ester structures. The indane skeleton represents the skeleton shown in the following formula (a1), and is preferably a trimethylindane skeleton shown in the following formula (a2). When the (A) polyimide precursor contains an amic acid structural unit or an amic acid ester structural unit, the indane skeleton is preferably included in a structural portion derived from a diamine compound.

The polyimide precursor (A) preferably contains a radical reactive group in the molecule of the polyimide precursor (A). The radical reactive group represents a reactive group that can undergo polymerization by radicals generated by heat or light, and examples thereof include groups containing non-aromatic carbon-carbon unsaturated bonds. When the polyimide precursor (A) containing a radical reactive group is used, the polyimide precursor (A) is polymerized by exposure to light, and the solubility of the photosensitive resin composition in the developer can be effectively reduced. Thus, the limiting resolution and undercut resistance can be particularly improved. For example, the radical reactive group may be contained in the esterified portion of the amic acid ester structural unit.

Examples of the tetracarboxylic dianhydride include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides, with aliphatic tetracarboxylic dianhydrides being preferred. Examples of the tetracarboxylic dianhydride include 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, 3,4,9,10-perylene tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-para-terphenyl tetracarboxylic dianhydride, 3,3',4,4'-meta-terphenyl tetracarboxylic dianhydride, 1,2, Examples of the tetracarboxylic dianhydride include 4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2-endo-3-endo-5-exo-6-exo-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2-exo-3-exo-5-exo-6-exo-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, and decahydro-dimethanonaphthalenetetracarboxylic dianhydride. The tetracarboxylic dianhydride may be used alone or in combination of two or more.

Examples of the diamine compound include bis[2-(3-aminopropoxy)ethyl]ether, 1,4-butanediol-bis(3-aminopropyl)ether, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro-5,5-undecane, 1,2-bis(2-aminoethoxy)ethane, 1,2-bis(3-aminopropoxy)ethane, triethylene glycol-bis(3-aminopropyl)ether, polyethylene glycol-bis(3-aminopropyl)ether, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro-5,5-undecane, 1,4-butanediol-bis(3-aminopropyl)ether, and 4,4'-diaminodiphenyl ether. The diamine compound may be used alone or in combination of two or more. In addition, as the diamine compound, a diamine compound containing an aromatic ring is preferable, and a diamine compound containing an indane skeleton is more preferable. Examples of the diamine compound containing an indane skeleton include the diamine compounds shown in the following formulas (a-1) to (a-8).

From the viewpoint of limiting resolution, it is preferable that the (A) polyimide precursor contains a structural unit represented by the following formula (A-1). Usually, the structural unit represented by formula (A-1) corresponds to an amic acid structural unit and an amic acid ester structural unit.

（式中、Ａはそれぞれ独立に４価の有機基を表し、Ｂはそれぞれ独立にインダン骨格を有する２価の有機基を表し、Ｒ^１及びＲ^２はそれぞれ独立に、水素原子又は１価の有機基を表す。ｎは５～２００の整数を表す。）

(In the formula, each A independently represents a tetravalent organic group, each B independently represents a divalent organic group having an indane skeleton, ^R1 and ^R2 independently represent a hydrogen atom or a monovalent organic group, and n represents an integer of 5 to 200.)

In formula (A-1), A each independently represents a tetravalent organic group. The tetravalent organic group is preferably a tetravalent organic group having 6 to 40 carbon atoms. Examples of the tetravalent organic group having 6 to 40 carbon atoms include an aromatic group in which the -COOR ¹ group and the -COOR ² group and the -CONH- group are in the ortho position with respect to each other, or an alicyclic aliphatic group (R ¹ and R ² are the same as R ¹ and R ² in formula (A-1). Examples of such groups include groups (i) to (ix). Among them, A is preferably a tetravalent organic group exemplified below, and more preferably a group (ii), a group (viii), or a group (ix). In the formula, * represents a bond.

The above-mentioned tetravalent organic group may have a substituent. Examples of the substituent include linear, branched, or cyclic alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, and n-butyl groups; halogen atoms, such as fluorine, chlorine, and bromine; alkoxy groups having 1 to 10 carbon atoms, such as methoxy, ethoxy, and propoxy groups; hydroxy groups; and halogen-substituted alkyl groups, such as trifluoromethyl groups. Of these, alkyl groups are preferred. The above-mentioned substituents may further have a substituent (hereinafter sometimes referred to as "secondary substituents"). The substituents may be of one type or of two or more types.

In formula (A-1), each B independently represents a divalent organic group. The divalent organic group preferably contains an aromatic ring. The divalent organic group more preferably contains an indane skeleton. Furthermore, the divalent organic group more preferably contains an aromatic ring in addition to the indane skeleton.

Examples of divalent organic groups include the groups (1a) to (28a) exemplified below. A group that combines two or more of the groups (1a) to (28a) may also be used as the divalent organic group. Among these, B is preferably a group (1a) to (28a), and more preferably either a group (7a) or a group (28a). In the formula, * represents a bond.

The divalent organic group may have a substituent. Examples of the substituent include the same ones that the tetravalent organic group may have. The substituent may be one type or two or more types.

In formula (A-1), R ¹ and R ² each independently represent a hydrogen atom or a monovalent organic group. Examples of the monovalent organic group include a radical reactive group and a saturated aliphatic group having 1 to 4 carbon atoms, and the radical reactive group is preferred. As the radical reactive group, for example, a group containing an ethylenically unsaturated bond may be used. The ethylenically unsaturated bond represents a non-aromatic carbon-carbon unsaturated bond. Specific examples of the radical reactive group include a vinyl group, an allyl group, a propargyl group, an ethynyl group, a phenylethynyl group, a butenyl group, a maleimide group, a nadimide group, a (meth)acryloyl group, and a group represented by formula (A-2) described below. The term "(meth)acryloyl group" includes a methacryloyl group, an acryloyl group, and a combination thereof. It is preferable that at least one of R ¹ and R ² in formula (A-1) is independently a radical reactive group, and it is more preferable that both are radical reactive groups. As the radical reactive group, a group represented by the following formula (A-2) is particularly preferred.

（式中、Ｒ^４～Ｒ^６は、それぞれ独立に、水素原子又は炭素原子数１～３の脂肪族炭化水素基を表し、ｐは１～１０の整数を表す。＊は結合手を表す。）

(In the formula, R ⁴ to R ⁶ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, p represents an integer of 1 to 10, and * represents a bond.)

R ⁴ to R ⁶ in formula (A-2) each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms. Examples of the aliphatic hydrocarbon group having 1 to 3 carbon atoms include an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and a 2-propyl group, and among these, a methyl group is preferred.

In formula (A-2), p represents an integer from 1 to 10, preferably an integer from 1 to 5, more preferably an integer from 1 to 3, and even more preferably 2.

The saturated aliphatic groups having 1 to 4 carbon atoms exemplified as ^R1 and ^R2 are preferably alkyl groups having 1 to 4 carbon atoms. Examples of the saturated aliphatic groups having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, and an n-butyl group.

In formula (A-1), it is preferable that at least one of R ¹ and R ² is independently a radical reactive group, it is more preferable that at least one of R ^{1 and R 2 is a group represented by formula (A-2), and it is further preferable that both R 1} and R ² are a group represented by formula (A-2).

In formula (A-1), n typically represents an integer of 5 to 200, preferably an integer of 5 to 150, more preferably an integer of 5 to 100, and even more preferably an integer of 5 to 70.

It is further preferred that the polyimide precursor (A) contains a structural unit represented by formula (A-3).

（式中、Ａ１はそれぞれ独立に４価の有機基を表し、Ｒ^１１及びＲ^１２はそれぞれ独立に、水素原子又は１価の有機基を表し、Ｒ^１３はそれぞれ独立に、水素原子又はメチル基を表し、Ｘａはそれぞれ独立に、単結合、下記式（１）で表される基、又は式（２）で表される基を表し、Ｘｂはそれぞれ独立に、単結合、式（３）で表される基、又は式（４）で表される基を表す。ｍ１は１～５の整数を表し、ｎ１は５～２００の整数を表す。）

（式（１）～（４）中、＊は結合手を表す。）

(In the formula, A1 each independently represents a tetravalent organic group, R ¹¹ and R ¹² each independently represent a hydrogen atom or a monovalent organic group, R ¹³ each independently represent a hydrogen atom or a methyl group, Xa each independently represent a single bond, a group represented by the following formula (1) or a group represented by formula (2), and Xb each independently represent a single bond, a group represented by formula (3) or a group represented by formula (4). m1 represents an integer of 1 to 5, and n1 represents an integer of 5 to 200.)

(In formulas (1) to (4), * represents a bond.)

Each A1 in formula (A-3) independently represents a tetravalent organic group, and A1 is the same as A in formula (A-1).

R ¹¹ and R ¹² in formula (A-3) each independently represent a hydrogen atom or a monovalent organic group and are the same as R ¹ and R ² in formula (A-1).

Each Xa independently represents a single bond, a group represented by formula (1), or a group represented by formula (2). Examples of the group represented by formula (1) include a 1,2-phenylene group, a 1,3-phenylene group, and a 1,4-phenylene group. Examples of the group represented by formula (2) include the following groups (2-1) to (2-6).

Among these, Xa is preferably a group represented by formula (2), and more preferably a group represented by formula (2-1).

Each Xb independently represents a single bond, a group represented by formula (3), or a group represented by formula (4). Examples of the group represented by formula (3) include a 1,2-phenylene group, a 1,3-phenylene group, and a 1,4-phenylene group. Examples of the group represented by formula (4) include the following groups. In the formula, * represents a bond.

Among these, Xb is preferably a group represented by formula (3), and more preferably a 1,4-phenylene group.

Each R ¹³ independently represents a hydrogen atom or a methyl group, and preferably represents a methyl group.

m1 represents an integer from 1 to 5, preferably an integer from 1 to 3, more preferably 2 or 3, and even more preferably 3.

n1 represents an integer from 5 to 200 and is the same as n in formula (A-1).

（式中、Ａ２はそれぞれ独立に４価の有機基を表し、Ｒ^２１又はＲ^２２は、それぞれ独立に水素原子又は下式（Ａ－５）で表される基を表す。ｎ２は５～２００の整数を表す。）

（式中、Ｒ^１４～Ｒ^１６は、それぞれ独立に、水素原子又は炭素原子数１～３の脂肪族炭化水素基を表し、ｐ１は１～１０の整数を表す。） The component (A) preferably has a structural unit represented by the following (A-4).

(In the formula, A2 each independently represents a tetravalent organic group, R ²¹ and R ²² each independently represent a hydrogen atom or a group represented by the following formula (A-5), and n2 represents an integer of 5 to 200.)

(In the formula, R ¹⁴ to R ¹⁶ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and p1 represents an integer of 1 to 10.)

Each A2 in formula (A-4) independently represents a tetravalent organic group and is the same as A in formula (A-1).

R ²¹ and R ²² in formula (A-4) each independently represent a hydrogen atom or a group represented by formula (A-5), with the group represented by formula (A-5) being preferred. R ¹⁴ to R ¹⁶ in the group represented by formula (A-5) each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms and are the same as R ⁴ to R ⁶ in the group represented by formula (A-2). p1 in the group represented by formula (A-5) represents an integer of 1 to 10 and is the same as p in the group represented by formula (A-2).

n2 represents an integer from 5 to 200 and is the same as n in formula (A-1).

Component (A) may be a copolymer that contains structural units that do not contain an indane skeleton, in addition to structural units that have an indane skeleton. For example, component (A) may contain structural units that do not contain an indane skeleton, in addition to structural units that contain an indane skeleton, as represented by formula (A-1).

The polyimide precursor (A) may contain any structural unit other than the above-mentioned amic acid structural unit and amic acid ester structural unit. Thus, the polyimide precursor (A) may be a copolymer containing the structural unit represented by formula (A-1) and any structural unit. In particular, the polyimide precursor (A) preferably contains a large amount of amic acid structural units and amic acid ester structural units, and therefore, it is preferable that the amount of any structural unit is small. For example, the mass of the amic acid structural unit and the amic acid ester structural unit is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more, based on the total mass of the polyimide precursor (A) (100%). The polyimide precursor (A) may contain only the above-mentioned amic acid structural unit and/or amic acid ester structural unit as a repeating unit, and therefore may not contain any structural unit. The amic acid structural unit and/or amic acid ester structural unit contained in the polyimide precursor (A) may be one type or two or more types.

Specific examples of the component (A) include the following compounds (A1) to (A14). However, the component (A) is not limited to these specific examples. In the formula, n represents an integer of 5 to 200.

From the viewpoint of film-forming ability and limiting resolution, the weight-average molecular weight of component (A) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 50,000 or more, and is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 200,000 or less. The weight-average molecular weight of the resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

The method for producing the polyimide precursor (A) is not particularly limited. The polyimide precursor (A) can be produced, for example, by a method including reacting a tetracarboxylic dianhydride with a diamine compound. Specific examples of the method for producing the polyimide precursor (A) include the production methods described in JP-A-2015-209461, JP-A-2015-214680, JP-A-2017-219850, and JP-A-2018-146964.

From the viewpoint of improving the limiting resolution, the content of component (A) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, when the non-volatile components of the photosensitive resin composition are taken as 100% by mass.

In the present invention, the content of each component in the photosensitive resin composition is the value when the non-volatile components in the photosensitive resin composition are taken as 100 mass %, unless otherwise specified, and the non-volatile components refer to all non-volatile components in the photosensitive resin composition excluding the solvent.

<(B) Radical Generator>
The photosensitive resin composition contains a radical generator (B) as the component (B). The component (B) generates radicals when heated or irradiated with active light, and the crosslinking reaction can proceed by the radicals. The radical generator (B) may be either a thermal radical generator that generates radicals when heated, or a photoradical generator that generates radicals when irradiated with active light, but from the viewpoint of limit resolution, a photoradical generator is preferred. The component (B) may be used alone or in combination of two or more. In addition, the component (B) does not include those that correspond to the component (A).

Examples of component (B) include oxime ester-based photopolymerization initiators, aminoketone-based photopolymerization initiators, acylphosphine-based photopolymerization initiators, α-hydroxyketone-based photopolymerization initiators, benzoin-based photopolymerization initiators, and benzyl ketal-based photopolymerization initiators.

Examples of oxime ester photopolymerization initiators include 2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one (OXE01), [1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-yl]ethylideneamino]acetate (OXE02), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), etc.

Examples of aminoketone-based photopolymerization initiators include α-aminoketone-based photopolymerization initiators such as 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-methyl-1-(4-hexylphenyl)-2-morpholinopropan-1-one, 2-ethyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, 2-(dimethylamino)-2-(4-methylphenylmethyl)-1-(4-morpholinophenyl)butan-1-one, and 2-methyl-1-(9,9-dibutylfluoren-2-yl)-2-morpholinopropan-1-one.

Examples of acylphosphine photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, polyoxyethylene glycerin ether tris[phenyl(2,4,6-trimethylbenzoyl)phosphinate] (Polymeric TPO-L), etc.

Examples of α-hydroxyketone photopolymerization initiators include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, etc.

Examples of benzoin-based photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Benzyl ketal photopolymerization initiators include, for example, 2,2-dimethoxy-2-phenylacetophenone.

From the viewpoint of limiting resolution, component (B) preferably contains one or more types selected from the group consisting of oxime ester photopolymerization initiators, aminoketone photopolymerization initiators, and acylphosphine photopolymerization initiators, and more preferably contains an oxime ester photopolymerization initiator.

Component (B) may be a commercially available product. Specific examples of commercially available products of component (B) include "Omnirad 907", "Omnirad 369", "Omnirad 379", "Omnirad 379EG", "Omnirad 819", and "Omnirad TPO" manufactured by IGM; "Irgacure TPO", "Irgacure OXE-01", and "Irgacure OXE-02" manufactured by BASF; and "N-1919" manufactured by ADEKA.

From the viewpoint of limiting resolution, the content of component (B) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of component (A), and is preferably 3 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1 part by mass or less.

From the viewpoint of limiting resolution, the content of component (B) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, when the non-volatile components of the photosensitive resin composition are taken as 100% by mass, and is preferably 3% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1% by mass or less.

<(C) Photocrosslinking agent with tetrafunctional or less>
The photosensitive resin composition contains a tetrafunctional or lower photocrosslinking agent (C) as the component (C). The tetrafunctional or lower photocrosslinking agent (C) as the component (C) does not include those corresponding to the components (A) and (B). By including the component (C) in the photosensitive resin composition, the limit resolution can be improved. The component (C) may be used alone or in combination of two or more types.

As the (C) component, a compound having 4 or less functionalities and capable of proceeding with a crosslinking reaction upon exposure can be used. As such a (C) component, a compound containing a group having an ethylenically unsaturated bond as a functional group (hereinafter sometimes referred to as an "ethylenically unsaturated group") having 4 or less functionalities is preferred. Furthermore, as the (C) component, a compound containing an ethylenically unsaturated group, at least one of the carbon atoms at the α position of the ethylenically unsaturated group is more preferred, in which a carbon atom at the α position of the ethylenically unsaturated group is bonded to a carbonyl group or an aromatic group. The carbon atom at the α position of the ethylenically unsaturated group refers to the first carbon atom adjacent to the carbon atom bonded by a carbon-carbon unsaturated bond. The ethylenically unsaturated group is usually a monovalent group, and examples thereof include a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, and a (meth)acryloyl group. From the viewpoint of limit resolution, a (meth)acryloyl group and a phenylethynyl group are preferred, a (meth)acryloyl group is more preferred, and a methacryloyl group is particularly preferred.

The number of ethylenically unsaturated groups (number of functional groups) per molecule of component (C) is 4 or less, preferably 3 or less, and more preferably 2 or less. There is no particular lower limit, but it is 1 or more. When component (C) contains 2 to 4 ethylenically unsaturated groups per molecule, those ethylenically unsaturated groups may be the same or different.

（式中、Ｒ^１ｃは、それぞれ独立に、水素原子、又は炭素原子数１～４の直鎖状もしくは分岐状アルキル基を表し、Ｚは、それぞれ独立に、酸素原子を含んでもよい炭素原子数１～２０の直鎖状もしくは分岐状のアルキレン基、酸素原子を含んでもよいアリーレン基、又は酸素原子を含んでもよい炭素原子数２～２０の直鎖状もしくは分岐状のアルケニレン基を表し、Ａ^１ｃは、炭素原子数１～１０の直鎖状、環状もしくは分岐状のｎｃ価の有機基を表す。ｎｃは２～６の正の整数を示す。） The component (C) is preferably a compound represented by the following general formula (C-1).

(In the formula, R ^1c each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms; Z each independently represents a linear or branched alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, an arylene group which may contain an oxygen atom, or a linear or branched alkenylene group having 2 to 20 carbon atoms which may contain an oxygen atom; A ^1c represents a linear, cyclic or branched organic group having 1 to 10 carbon atoms and having n c valence, where n is a positive integer of 2 to 6.)

Each R ^1c independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 1-butyl group, a s-butyl group, and a t-butyl group. Among these, a hydrogen atom or a methyl group is preferable as R ^1c .

Z each independently represents a linear or branched alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, an arylene group which may contain an oxygen atom, or a linear or branched alkenylene group having 2 to 20 carbon atoms which may contain an oxygen atom. As the linear or branched alkylene group having 1 to 20 carbon atoms, a linear or branched alkylene group having 1 to 10 carbon atoms is preferred, and a linear or branched alkylene group having 1 to 6 carbon atoms is more preferred. Examples of such alkylene groups include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, and a methylene group is preferred. The alkylene group may also be an oxyalkylene group containing an oxygen atom, and specific examples of such groups include, for example, those shown below. In the formula, "*" represents a bond, c1 represents an integer of 1 to 20, c2 represents an integer of 1 to 10, c3 represents an integer of 1 to 19, and c4 represents an integer of 1 to 9.

The arylene group which may contain an oxygen atom is preferably an arylene group having 6 to 20 carbon atoms, more preferably an arylene group having 6 to 15 carbon atoms, and even more preferably an arylene group having 6 to 10 carbon atoms. Examples of such an arylene group include a phenylene group and a naphthylene group. The arylene group may also contain an oxygen atom, and specific examples of such groups include those shown below. In the formula, "*" represents a bond, and c5 represents an integer of 1 to 3.

As the linear or branched alkenylene group having 2 to 20 carbon atoms which may contain an oxygen atom, a linear or branched alkenylene group having 2 to 10 carbon atoms is preferred, and a linear or branched alkenylene group having 2 to 6 carbon atoms is more preferred. Examples of such an alkenylene group include an ethenylene group, a propenylene group, a butenylene group, a pentenylene group, and a hexenylene group. The alkenylene group may also be an oxyalkenylene group containing an oxygen atom, and specific examples of such groups include those shown below. In the formula, "*" represents a bond, and c6 represents an integer of 1 to 10. As the alkenylene group, a propenylene group is preferred.

Among these, Z is preferably a linear or branched alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, and more preferably an oxyalkylene group.

A ^1c represents a linear, cyclic or branched nc-valent organic group having 1 to 10 carbon atoms. Examples of the nc-valent organic group include an nc-valent hydrocarbon group which may contain an oxygen atom, an nc-valent group derived from bisphenol, an nc-valent group derived from fluorene, an nc-valent group derived from tricyclodecane, or an nc-valent group derived from an isocyanuric group. Examples of the nc-valent hydrocarbon group which may contain an oxygen atom include an nc-valent aliphatic hydrocarbon group which may contain an oxygen atom, and an nc-valent aromatic hydrocarbon group which may contain an oxygen atom. An nc-valent aliphatic hydrocarbon group which may contain an oxygen atom is preferred, and when nc is 2, an alkylene group is preferred. Specific examples of the group represented by A ^1c include, for example, those shown below. In the formula, "*" represents a bond.

n c is a positive integer from 2 to 6, preferably a positive integer from 2 to 5, more preferably a positive integer from 3 to 5, and even more preferably 2 to 4, 3 or 4, or 2 or 3.

（式（Ｃ－２）中、Ｒ^２ｃは、それぞれ独立に水素原子、又はメチル基を表す。） The component (C) is preferably a compound represented by the following general formula (C-2).

(In formula (C-2), R ^2c each independently represents a hydrogen atom or a methyl group.)

R ^2c represents a hydrogen atom or a methyl group, and is preferably a methyl group.

Specific examples of the component (C) include the following compounds (CL-1) to (CL-11), however, the component (C) is not limited to these.

Component (C) may be a commercially available product. Examples of commercially available products include NK Ester D-TMP, 4G, 9G, 14G, 23G, DCP, TMPT, and A-TMPT manufactured by Shin-Nakamura Chemical Co., Ltd., and SR209 manufactured by Sartomer Japan, Inc.

From the viewpoint of obtaining a significant effect of the present invention, the content of component (C) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of component (A), and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less.

From the viewpoint of obtaining a significant effect of the present invention, the content of component (C) is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, when the total amount of components (A) and (B) is taken as 100 parts by mass, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less.

From the viewpoint of obtaining a significant effect of the present invention, the content of component (C) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, when the non-volatile components of the photosensitive resin composition are taken as 100% by mass, and is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less.

<(D) Pentafunctional or higher photocrosslinking agent>
The photosensitive resin composition contains a pentafunctional or higher photocrosslinking agent as the (D) component. The pentafunctional or higher photocrosslinking agent as the (D) component does not include those corresponding to the (A), (B), and (C) components. By including the (D) component in the photosensitive resin composition, the limit resolution can be improved. In addition, by using the (D) component in combination with the (C) component, it is possible to widen the process window. The (D) component may be used alone or in combination of two or more types.

As the (D) component, a compound having five or more functionalities and capable of proceeding with a crosslinking reaction upon exposure can be used. As such a (D) component, a compound containing five or more functional ethylenically unsaturated groups as functional groups is preferable. Furthermore, as the (D) component, a compound containing an ethylenically unsaturated group, in which at least one carbon atom at the α-position of the ethylenically unsaturated group is bonded to a carbonyl group or an aromatic group is more preferable. The ethylenically unsaturated group is usually a monovalent group, and examples thereof include a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, and a (meth)acryloyl group. From the viewpoint of limit resolution, a (meth)acryloyl group or a phenylethynyl group is preferable, a (meth)acryloyl group is more preferable, and a methacryloyl group is particularly preferable.

The number of ethylenically unsaturated groups (functionality) per molecule of component (D) is 5 or more, preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less. The ethylenically unsaturated groups per molecule of component (D) may be the same or different.

When the number of functional groups per molecule of component (D) is D1 and the number of functional groups per molecule of component (C) is C1, C1/D1 is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and even more preferably 0.4 or more. The upper limit is preferably 0.8 or less, more preferably 0.7 or less, and even more preferably 0.75 or less. By adjusting the number of functional groups of component (C) and the number of functional groups of component (D) so that C1/D1 falls within this range, it is possible to obtain a photosensitive resin composition that has excellent limiting resolution and a wide process window.

式中、Ｒ^１ｄは、それぞれ独立に、水素原子、又は炭素原子数１～４の直鎖状もしくは分岐状アルキル基を表し、Ａ^１ｄは、ｎｄ価の多価アルコールから誘導されたｎｄ価の基を表す。ｎｃは５以上の整数を示す。 The component (D) is preferably a compound represented by the following formula (D-1).

In the formula, R ^1d each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, A ^1d represents an nd-valent group derived from an nd-valent polyhydric alcohol, and nc represents an integer of 5 or more.

Each R ^1d independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 1-butyl group, a s-butyl group, and a t-butyl group. Of these, a hydrogen atom or a methyl group is preferable as R ^1d .

A ^1d represents an nd-valent group derived from an nd-valent polyhydric alcohol. An nd-valent polyhydric alcohol is a compound having nd or more hydroxyl groups, and A ^1d represents a skeleton portion of the polyhydric alcohol other than the hydroxyl groups, and in the case of a hexahydric or higher polyhydric alcohol, A 1d may have unreacted hydroxyl groups. The number of carbon atoms of the polyhydric alcohol used as the raw material for A ^1d is preferably 2 to 20.

Examples of polyhydric alcohols include trimethylolpropane, trimethylolethane, pentaerythritol, and dipentaerythritol.

Specific examples of the group represented by A ^1d include the following: In the formula, "*" represents a bond.

Examples of compounds represented by formula (D-1) include dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and mixtures thereof.

Component (D) may be a commercially available product. Examples of commercially available products include DPHA manufactured by Nippon Kayaku Co., Ltd., and CN2301 and CN2304 manufactured by Sartomer Japan Co., Ltd.

From the viewpoint of obtaining a significant effect of the present invention, the content of component (D) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of component (A), and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less.

From the viewpoint of obtaining a significant effect of the present invention, the content of the (D) component is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, when the total amount of the (A) component and the (B) component is taken as 100 parts by mass, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less.

From the viewpoint of obtaining a significant effect of the present invention, the content of component (D) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, when the non-volatile components of the photosensitive resin composition are taken as 100% by mass, and is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less.

When the content of the (C) component when the non-volatile components of the photosensitive resin composition are taken as 100% by mass is Cw, and the content of the (D) component when the non-volatile components of the photosensitive resin composition are taken as 100% by mass is Dw, Cw/Dw is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 0.8 or more, and is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. By adjusting the contents of the (C) and (D) components so that Cw/Dw falls within this range, it is possible to obtain a photosensitive resin composition that has excellent limit resolution and a wide process window.

<(E) Other Additives>
The photosensitive resin composition may further contain (E) other additives to the extent that the object of the present invention is not hindered. (E) other additives include, for example, adhesion aids; surfactants such as fluorine-based surfactants, nonionic surfactants, cationic surfactants, anionic surfactants, and silicone-based surfactants; thermoplastic resins; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, carbon black, and naphthalene black; polymerization inhibitors such as hydroquinone, phenothiazine, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol; thickeners such as bentone and montmorillonite; silicone-based, fluorine-based, and vinyl resin-based defoamers; flame retardants such as epoxy resins, antimony compounds, phosphorus-based compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters; and thermosetting resins such as phenol-based curing agents and cyanate ester-based curing agents.

<(F) Solvent>
The photosensitive resin composition may contain a solvent (F) as an optional component in combination with the non-volatile components such as the above-mentioned components (A) to (E). The solvent (F) is a volatile component, and is preferably capable of uniformly dissolving at least any one of the components (A) to (D) and the optional component (E). Examples of such a solvent include ether compounds having 2 to 9 carbon atoms, such as dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; ketone compounds having 2 to 6 carbon atoms, such as acetone and methyl ethyl ketone; saturated hydrocarbon compounds having 5 to 10 carbon atoms, such as normal pentane, cyclopentane, normal hexane, cyclohexane, methylcyclohexane, and decalin; benzene, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; Examples of the aromatic hydrocarbon compounds include aromatic hydrocarbon compounds having 6 to 10 carbon atoms, such as benzene, xylene, mesitylene, and tetralin; ester compounds having 3 to 9 carbon atoms, such as methyl acetate, ethyl acetate, γ-butyrolactone, and methyl benzoate; halogen-containing compounds having 1 to 10 carbon atoms, such as chloroform, methylene chloride, and 1,2-dichloroethane; nitrogen-containing compounds having 2 to 10 carbon atoms, such as acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; and sulfur-containing compounds such as dimethyl sulfoxide.

Examples of the (F) component include N-ethyl-2-pyrrolidone, tetrahydrofuran, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, pyridine, cyclopentanone, α-acetyl-γ-butyrolactone, tetramethylurea, 1,3-dimethyl-2-imidazolinone, N-cyclohexyl-2-pyrrolidone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, methyl isobutyl ketone, anisole, ethyl acetate, ethyl lactate, and butyl lactate. The (F) component may be used alone or in combination of two or more.

The content of the (F) component is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, and preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, when the entire photosensitive resin composition including component (F) is taken as 100% by mass. The content of the (F) component in the photosensitive resin composition layer of the photosensitive film is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, when the entire photosensitive resin composition including component (F) is taken as 100% by mass.

The photosensitive resin composition can be produced by mixing the above-mentioned components (A) to (D) as essential components, appropriately mixing the above-mentioned component (E) as an optional component, and kneading or stirring as necessary with kneading means such as a triple roll mill, ball mill, bead mill, or sand mill, or stirring means such as a super mixer or planetary mixer.

<Properties and Applications of Photosensitive Resin Composition>
The photosensitive resin composition exhibits the characteristic of being excellent in limit resolution. For example, exposure and development are performed using a mask that draws circular holes with opening diameters of 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, and 70 μm in the exposure pattern. In this case, the limit resolution, which is the minimum size that can be opened, is preferably 60 μm or less, more preferably 40 μm or less. The limit resolution can be evaluated according to the method described in the examples below.

The photosensitive resin composition exhibits the characteristic of a wide process window. For example, a mask that draws round holes with opening diameters of 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, and 70 μm in the exposure pattern is used, and the exposure dose is set to the ranges of 200 mJ/cm ² , 300 mJ/cm ² , 400 mJ/cm ² , and 500 mJ/cm ² , respectively, and development is performed. In this case, the limiting resolution, which is the minimum size that can be opened, is preferably 60 μm or less, more preferably 40 μm or less even if the exposure dose is changed.

Photosensitive resin compositions usually exhibit excellent undercut resistance. For example, a photosensitive resin composition layer is prepared on a silicon wafer. The photosensitive resin composition layer is exposed to light and developed to form round holes. Among these round holes, the undercut of the smallest round hole (threshold opening via) that can be opened without residue or peeling can be preferably 4 μm or less, more preferably less than 2 μm, and particularly preferably no undercut can be obtained. The undercut resistance can be measured according to the method described in the examples below.

The photosensitive resin composition of the present invention can be used in a wide range of applications, including, but not limited to, photosensitive films, insulating resin sheets such as prepregs, silicon wafers, circuit boards (for laminates, multilayer printed wiring boards, etc.), solder resists, buffer coat films, underfill materials, die bonding materials, semiconductor encapsulants, hole-filling resins, and component-embedding resins. Among these, the photosensitive resin composition can be used in a wide range of applications, including, but not limited to, photosensitive resin compositions for insulating layers of printed wiring boards (printed wiring boards in which the cured product of the photosensitive resin composition is the insulating layer), photosensitive resin compositions for interlayer insulating layers (printed wiring boards in which the cured product of the photosensitive resin composition is the interlayer insulating layer), photosensitive resin compositions for plating (printed wiring boards in which plating is formed on the cured product of the photosensitive resin composition), and photosensitive resin compositions for solder resists (printed wiring boards in which the cured product of the photosensitive resin composition is the solder resist), photosensitive resin compositions for rewiring formation layers of wafer-level packages (wafer-level packages in which the cured product of the photosensitive resin composition is the rewiring formation layer), It can be suitably used as a photosensitive resin composition for a rewiring formation layer of a fan-out wafer level package (a fan-out wafer level package in which a cured product of a photosensitive resin composition is used as a rewiring formation layer), a photosensitive resin composition for a rewiring formation layer of a fan-out panel level package (a fan-out panel level package in which a cured product of a photosensitive resin composition is used as a rewiring formation layer), a photosensitive resin composition for a buffer coat (a semiconductor device in which a cured product of a photosensitive resin composition is used as a buffer coat), and a photosensitive resin composition for an insulating layer for a display (a display in which a cured product of a photosensitive resin composition is used as an insulating layer).

[Photosensitive film]
The photosensitive resin composition of the present invention can be applied to a photosensitive film. The photosensitive film can include a support and a photosensitive resin composition layer formed on the support. The photosensitive resin composition layer is a layer made of the above-mentioned photosensitive resin composition. The photosensitive film may also include a support, a photosensitive resin composition layer, and a protective film (cover film) in this order.

Examples of the support include polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polyethylene film, polyvinyl alcohol film, triacetyl acetate film, etc., with polyethylene terephthalate film being particularly preferred.

Commercially available supports include, but are not limited to, polypropylene films such as those manufactured by Oji Paper under the product names "Alphan MA-410" and "E-200C," those manufactured by Tamapoly under the product names "GF-1" and "GF-8," those manufactured by Shin-Etsu Film, and those manufactured by Teijin under the product name "PS-25" and other polyethylene terephthalate films in the PS series. To facilitate removal, it is preferable that the surface of these supports is coated with a release agent such as a silicone coating agent or a non-silicone coating agent. An example of a support whose surface has been treated with such a release agent is "AL-5" manufactured by Lintec. The thickness of the support is preferably in the range of 5 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm.

The thickness of the photosensitive resin composition layer is not particularly limited and can be, for example, 1 μm or more and 100 μm or less. In particular, it is preferably 2 μm or more, more preferably 4 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less.

The photosensitive resin composition layer may be protected by a protective film. By protecting the photosensitive resin composition layer with a protective film, adhesion of dust and scratches to the surface of the photosensitive resin composition layer can be suppressed. As the protective film, for example, a film made of the same material as the above-mentioned support can be used. The thickness of the protective film is not particularly limited, but is preferably in the range of 1 μm to 40 μm, more preferably in the range of 5 μm to 30 μm, and even more preferably in the range of 10 μm to 30 μm. It is preferable that the adhesive strength between the photosensitive resin composition layer and the protective film is smaller than the adhesive strength between the photosensitive resin composition layer and the support.

The photosensitive film can be produced, for example, by applying the photosensitive resin composition onto a support and, if necessary, drying the component (H).

[Semiconductor package substrate]
The semiconductor package substrate of the present invention includes an insulating layer formed from a cured product of the photosensitive resin composition of the present invention. The insulating layer is preferably used as a rewiring layer, an interlayer insulating layer, a buffer coat film, or a solder resist.

In detail, the semiconductor package substrate of the first embodiment of the present invention can be manufactured using the above-mentioned photosensitive resin composition, and the cured product of the photosensitive resin composition is used as an insulating layer.
(I) forming a photosensitive resin composition layer containing the photosensitive resin composition of the present invention on a circuit board;
(II) a step of irradiating the photosensitive resin composition layer with actinic rays; and (III) a step of developing the photosensitive resin composition layer.
Includes, in this order.

<Step (I)>
Methods for forming the photosensitive resin composition layer include a method in which a resin varnish containing the photosensitive resin composition is directly applied onto a circuit board, and a method in which the above-mentioned photosensitive film is used.

When a resin varnish containing a photosensitive resin composition is applied directly onto a circuit board, a photosensitive resin composition layer is formed on the circuit board by drying and volatilizing component (H).

Examples of resin varnish application methods include gravure coating, microgravure coating, reverse coating, kiss reverse coating, die coating, slot die, lip coating, comma coating, blade coating, roll coating, knife coating, curtain coating, chamber gravure coating, slot orifice, spin coating, slit coating, spray coating, dip coating, hot melt coating, bar coating, applicator, air knife coating, curtain flow coating, offset printing, brush coating, and full-surface printing using screen printing.

The resin varnish may be applied in several separate applications, or in one application, or a combination of different methods may be used. Of these, the die coating method is preferred, as it provides excellent uniformity of application. In addition, to avoid contamination by foreign matter, it is preferable to carry out the application process in an environment where foreign matter is unlikely to be generated, such as a clean room.

After the resin varnish is applied, it is dried in a hot air oven or far-infrared oven as necessary. Drying conditions are preferably 80°C to 120°C for 3 to 13 minutes. In this way, a photosensitive resin composition layer is formed on the circuit board.

Examples of circuit boards include glass epoxy boards, metal boards, polyester boards, polyimide boards, BT resin boards, and thermosetting polyphenylene ether boards. Here, the circuit board refers to a board in which a patterned conductor layer (circuit) is formed on one or both sides of the support board as described above. In addition, in a multilayer printed wiring board formed by alternately laminating conductor layers and insulating layers, a board in which one or both sides of the outermost layer of the multilayer printed wiring board are patterned conductor layers (circuits) is also included in the circuit board referred to here. Note that the surface of the conductor layer may be roughened in advance by blackening, copper etching, etc.

On the other hand, when a photosensitive film is used, the photosensitive resin composition layer side is laminated to one or both sides of the circuit board using a vacuum laminator. In the lamination process, if the photosensitive film has a protective film, the protective film is removed, and the photosensitive film and circuit board are preheated as necessary, and the photosensitive resin composition layer is pressed and heated while being bonded to the circuit board. For photosensitive films, a method of laminating to the circuit board under reduced pressure using a vacuum lamination method is preferably used.

The lamination conditions are not particularly limited, but for example, the lamination temperature is preferably 70°C to 140°C, the lamination pressure is preferably 1 kgf/cm ² to 11 kgf/cm ² (9.8×10 ⁴ N/m ² to 107.9×10 ⁴ N/m ² ), the lamination time is preferably 5 seconds to 300 seconds, and the air pressure is preferably 20 mmHg (26.7 hPa) or less under reduced pressure. The lamination process may be a batch process or a continuous process using a roll. The vacuum lamination method can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum applicator manufactured by Nikko Materials Co., Ltd., a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a roll-type dry coater manufactured by Hitachi Industries Co., Ltd., and a vacuum laminator manufactured by Hitachi AIC Co., Ltd.

<Step (II)>
After the photosensitive resin composition layer is provided on the circuit board, an exposure step is then performed in which a predetermined portion of the photosensitive resin composition layer is irradiated with active light through a mask pattern. Examples of active light include ultraviolet light, visible light, electron beams, and X-rays, and ultraviolet light is particularly preferred. The amount of ultraviolet light is approximately 10 mJ/cm ² to 1000 mJ/cm ^2. There are two types of exposure method: a contact exposure method in which a mask pattern is brought into close contact with the circuit board, and a non-contact exposure method in which exposure is performed using parallel light without contact, and either method may be used.

In step (II), vias can be formed using a via pattern such as a round hole pattern as the mask pattern. The via diameter (opening diameter) is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. There is no particular lower limit, but it can be 0.1 μm or more, 0.5 μm or more, etc.

<Step (III)>
After the exposure step, a development step is carried out in which the unexposed portions of the photosensitive resin composition layer are removed with a developer, thereby forming a pattern. The development is usually carried out by wet development.

In the case of the above-mentioned wet development, a developer that is safe, stable, and easy to operate, such as an alkaline solution, an aqueous developer, or an organic solvent, is used. In addition, as the development method, a known method such as spraying, rocking immersion, brushing, or scraping is appropriately used.

Examples of alkaline aqueous solutions used as the developer include aqueous solutions of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; carbonates or bicarbonates such as sodium carbonate and sodium bicarbonate; alkali metal phosphates such as sodium phosphate and potassium phosphate; and alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; and aqueous solutions of organic bases that do not contain metal ions, such as tetraalkylammonium hydroxide. An aqueous solution of tetramethylammonium hydroxide (TMAH) is preferred because it does not contain metal ions and does not affect the semiconductor chip.

These alkaline aqueous solutions may contain a surfactant, an antifoaming agent, etc., to improve the development effect. The pH of the alkaline aqueous solution is, for example, preferably in the range of 8 to 12, and more preferably in the range of 9 to 11. The base concentration of the alkaline aqueous solution is preferably 0.1% by mass to 10% by mass. The temperature of the alkaline aqueous solution can be appropriately selected according to the developability of the photosensitive resin composition layer, but is preferably 20°C to 50°C.

Organic solvents used as developers include, for example, acetone, ethyl acetate, alkoxyethanols having an alkoxy group with 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, cyclopentanone, and cyclohexanone.

The concentration of such an organic solvent is preferably 2% by mass to 90% by mass based on the total amount of the developer. The temperature of such an organic solvent can be adjusted according to the developability. Furthermore, such organic solvents can be used alone or in combination of two or more kinds. Examples of organic solvent-based developers used alone include 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone.

When forming a pattern, two or more development methods may be used in combination, if necessary. Development methods include the dip method, the stroke method, the spray method, the high-pressure spray method, brushing, and slapping, and the high-pressure spray method is suitable for improving resolution. When using the spray method, the spray pressure is preferably 0.05 MPa to 0.3 MPa.

<Thermal curing (post-bake) process>
After the above step (III) is completed, a heat curing (post-baking) step is performed as necessary. Although the curing of the photosensitive resin composition layer may proceed in the above steps (I) to (III), the curing of the photosensitive resin composition can be further promoted by the heat curing step to obtain an insulating layer having excellent mechanical strength. Usually, in this step (III), the polyimide precursor (A) is ring-closed to form an insulating layer containing polyimide. Examples of the post-baking step include a heating step using a clean oven. The atmosphere during the heat curing may be in air or in an inert gas atmosphere such as nitrogen. The heating conditions may be appropriately selected depending on the type and content of the resin component in the photosensitive resin composition, and are preferably selected in the range of 150°C to 250°C for 20 minutes to 180 minutes, and more preferably in the range of 160°C to 230°C for 30 minutes to 120 minutes.

<Other processes>
The method for producing a semiconductor package substrate may further include a drilling step and a desmearing step after forming an insulating layer as a cured photosensitive resin composition layer. These steps may be carried out according to various methods used in the production of semiconductor package substrates and known to those skilled in the art.

After forming the insulating layer, if desired, a drilling process is performed on the insulating layer formed on the circuit board to form via holes and through holes. The drilling process can be performed by known methods such as drilling, laser, plasma, etc., or by combining these methods as necessary, but a drilling process using a laser such as a carbon dioxide laser or YAG laser is preferred.

The desmear process is a process of performing a desmear treatment. Generally, resin residue (smear) adheres to the inside of the opening formed in the drilling process. Since such smears can cause poor electrical connections, a process to remove the smear (desmear treatment) is performed in this process.

The desmearing process may be performed by a dry desmearing process, a wet desmearing process, or a combination of these.

An example of a dry desmear process is a desmear process using plasma. A desmear process using plasma can be performed using a commercially available plasma desmear process. Among commercially available plasma desmear process devices, examples suitable for use in manufacturing semiconductor package substrates include a microwave plasma device manufactured by Nissin Co., Ltd. and an atmospheric plasma etching device manufactured by Sekisui Chemical Co., Ltd.

As the wet desmear treatment, for example, a desmear treatment using an oxidizing agent solution can be mentioned. When performing the desmear treatment using an oxidizing agent solution, it is preferable to perform the swelling treatment using a swelling liquid, the oxidation treatment using an oxidizing agent solution, and the neutralization treatment using a neutralizing liquid in this order. As the swelling liquid, for example, "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan can be mentioned. The swelling treatment is preferably performed by immersing the substrate on which the via holes and the like are formed in the swelling liquid heated to 60°C to 80°C for 5 to 10 minutes. As the oxidizing agent solution, an alkaline permanganate solution is preferable, and for example, a solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide can be mentioned. The oxidation treatment using the oxidizing agent solution is preferably performed by immersing the substrate after the swelling treatment in the oxidizing agent solution heated to 60°C to 80°C for 10 to 30 minutes. Commercially available alkaline permanganate aqueous solutions include, for example, "Concentrate Compact CP" and "Dosing Solution Securiganth P" manufactured by Atotech Japan. The neutralization treatment using a neutralizing solution is preferably carried out by immersing the substrate after the oxidation treatment in the neutralizing solution at 30°C to 50°C for 3 to 10 minutes. The neutralizing solution is preferably an acidic aqueous solution, and a commercially available product is, for example, "Reduction Solution Securiganth P" manufactured by Atotech Japan.

When dry desmear treatment and wet desmear treatment are performed in combination, the dry desmear treatment may be performed first, or the wet desmear treatment may be performed first.

Whether the insulating layer is formed as a redistribution layer, an interlayer insulating layer, or a solder resist, a drilling process and a desmearing process may be performed after the thermal curing process. In addition, in the manufacturing method of the semiconductor package substrate, a plating process may be further performed.

The plating process is a process for forming a conductor layer on an insulating layer. The conductor layer may be formed by sputtering after the insulating layer is formed, or may be formed by a combination of electroless plating and electrolytic plating. Alternatively, a plating resist having a reverse pattern to the conductor layer may be formed, and the conductor layer may be formed only by electroless plating. Subsequent pattern formation methods that can be used include, for example, subtractive methods and semi-additive methods known to those skilled in the art.

The semiconductor package substrate according to the second embodiment of the present invention can be manufactured using the above-mentioned photosensitive resin composition, and the cured product of the photosensitive resin composition is used as a rewiring formation layer. Specifically, the manufacturing method of the semiconductor package substrate includes:
(A) a step of laminating a temporary fixing film on a substrate;
(B) a step of temporarily fixing a semiconductor chip on a temporary fixing film;
(C) forming an encapsulation layer on the semiconductor chip;
(D) peeling the substrate and the temporary fixing film from the semiconductor chip;
(E) a step of forming a rewiring formation layer as an insulating layer on the surface of the semiconductor chip from which the base material and the temporary fixing film have been peeled off;
(F) forming a redistribution layer as a conductor layer on the redistribution layer; and
(G) forming a solder resist layer on the rewiring layer;
The method for manufacturing the semiconductor chip package further comprises:
(H) dicing the plurality of semiconductor chip packages into individual semiconductor chip packages;
may also include

<Step (A)>
Step (A) is a step of laminating a temporary fixing film on a substrate. The lamination conditions of the substrate and the temporary fixing film are not particularly limited, but for example, it is preferable to perform lamination under reduced pressure with a pressure bonding temperature (lamination temperature) of preferably 70°C to 140°C, a pressure bonding pressure of preferably 1 kgf/cm ² to 11 kgf/cm ² , a pressure bonding time of preferably 5 seconds to 300 seconds, and an air pressure of 20 mmHg or less. The lamination step may be a batch type or a continuous type using a roll. The vacuum lamination method can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum applicator manufactured by Nikko Materials Co., Ltd., a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a roll type dry coater manufactured by Hitachi Industries Co., Ltd., and a vacuum laminator manufactured by Hitachi AIC Co., Ltd.

Examples of substrates include silicon wafers; glass wafers; glass substrates; metal substrates such as copper, titanium, stainless steel, and cold-rolled steel plate (SPCC); substrates such as FR-4 substrates in which glass fibers are impregnated with epoxy resin or the like and then heat-cured; and substrates made of bismaleimide triazine resins such as BT resin.

The temporary fixing film can be made of any material that can be peeled off from the semiconductor chip and can temporarily fix the semiconductor chip. Commercially available products include "Riva Alpha" manufactured by Nitto Denko Corporation.

<Step (B)>
Step (B) is a step of temporarily fixing the semiconductor chip on the temporary fixing film. The temporary fixing of the semiconductor chip can be performed using, for example, a device such as a flip chip bonder or a die bonder. The layout and number of the semiconductor chips can be appropriately set depending on the shape and size of the temporary fixing film, the number of semiconductor packages to be produced, etc. For example, the semiconductor chips may be temporarily fixed by arranging them in a matrix shape of multiple rows and multiple columns.

<Step (C)>
Step (C) is a step of forming an encapsulating layer on the semiconductor chip. The encapsulating layer can be made of any material having insulating properties, and the above-mentioned photosensitive resin composition can be used. The encapsulating layer is usually formed by a method including a step of forming an encapsulating resin composition layer on the semiconductor chip and a step of thermally curing the resin composition layer to form the encapsulating layer.

The encapsulating resin composition layer is preferably formed by compression molding. In compression molding, the semiconductor chip and the encapsulating resin composition are typically placed in a mold, and pressure and, if necessary, heat are applied to the encapsulating resin composition in the mold to form an encapsulating resin composition layer that covers the semiconductor chip.

Specific operations of the compression molding method can be, for example, as follows. An upper mold and a lower mold are prepared as molds for compression molding. In addition, an encapsulating resin composition is applied to the semiconductor chip that has been temporarily fixed on the temporary fixing film as described above. The semiconductor chip to which the encapsulating resin composition has been applied is attached to the lower mold together with the substrate and the temporary fixing film. Thereafter, the upper mold and the lower mold are clamped together, and heat and pressure are applied to the encapsulating resin composition to perform compression molding.

Specific operations of the compression molding method may be, for example, as follows. An upper mold and a lower mold are prepared as molds for compression molding. An encapsulating resin composition is placed on the lower mold. A semiconductor chip is attached to the upper mold together with a substrate and a temporary fixing film. The upper and lower molds are then clamped together so that the encapsulating resin composition placed on the lower mold is in contact with the semiconductor chip attached to the upper mold, and heat and pressure are applied to perform compression molding.

The molding conditions vary depending on the composition of the encapsulating resin composition, and appropriate conditions can be adopted so that good encapsulation is achieved. For example, the temperature of the mold during molding is preferably a temperature at which the encapsulating resin composition can exhibit excellent compression moldability, and is preferably 80°C or higher, more preferably 100°C or higher, particularly preferably 120°C or higher, and preferably 200°C or lower, more preferably 170°C or lower, and particularly preferably 150°C or lower. The pressure applied during molding is preferably 1 MPa or higher, more preferably 3 MPa or higher, particularly preferably 5 MPa or higher, and preferably 50 MPa or lower, more preferably 30 MPa or lower, and particularly preferably 20 MPa or lower. The cure time is preferably 1 minute or higher, more preferably 2 minutes or higher, particularly preferably 5 minutes or higher, and preferably 60 minutes or lower, more preferably 30 minutes or lower, and particularly preferably 20 minutes or lower. Usually, the mold is removed after the encapsulating resin composition layer is formed. The mold may be removed before or after the encapsulating resin composition layer is thermally cured.

The compression molding method may be performed by discharging the encapsulating resin composition filled in a cartridge into a lower mold.

<Step (D)>
Step (D) is a step of peeling off the substrate and the temporary fixing film from the semiconductor chip. It is desirable to adopt an appropriate peeling method according to the material of the temporary fixing film. For example, the peeling method may include a method of heating, foaming or expanding the temporary fixing film to peel it off. In addition, for example, the peeling method may include a method of irradiating the temporary fixing film with ultraviolet light through the substrate to reduce the adhesive strength of the temporary fixing film to peel it off.

In the method of peeling off the temporary fixing film by heating, foaming or expanding it, the heating conditions are usually 100° C. to 250° C. for 1 second to 90 seconds or 5 minutes to 15 minutes. In the method of peeling off the temporary fixing film by reducing the adhesive strength of the temporary fixing film by irradiating it with ultraviolet light, the irradiation amount of ultraviolet light is usually 10 mJ/cm ² to 1000 mJ/cm ² .

<Step (E)>
Step (E) is a step of forming a rewiring formation layer as an insulating layer on the surface of the semiconductor chip from which the base material and the temporary fixing film have been peeled off. The rewiring formation layer uses the photosensitive resin composition of the present invention. The method for forming the rewiring formation layer is the same as the method for forming the photosensitive resin composition layer in step (I) in the first embodiment.

When forming the redistribution layer, via holes may be formed in the redistribution layer to provide interlayer connection between the semiconductor chip and the redistribution layer.

The via hole can be formed by carrying out an exposure process in which the surface of the photosensitive resin composition layer for forming the rewiring formation layer is irradiated with active light through a mask pattern, and a development process in which the non-exposed portion not irradiated with active light is developed and removed. The amount and duration of exposure of the active light can be appropriately set according to the photosensitive resin composition layer. Examples of the exposure method include a contact exposure method in which a mask pattern is brought into close contact with the photosensitive resin composition layer and exposed, and a non-contact exposure method in which a mask pattern is not brought into close contact with the photosensitive resin composition layer and exposed using parallel light. The active light, alkaline aqueous solution, and exposure and development methods are as described above.

The shape of the via hole is not particularly limited, but is generally circular (approximately circular). The top diameter of the via hole is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less, and is preferably 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1.0 μm or more. Here, the top diameter of the via hole refers to the diameter of the opening of the via hole on the surface of the rewiring formation layer.

<Step (F)>
Step (F) is a step of forming a redistribution layer as a conductor layer on the redistribution formation layer. The method of forming the redistribution layer on the redistribution formation layer may be the same as the method of forming a conductor layer on an insulating layer in the first embodiment. Steps (E) and (F) may be repeated to alternately stack (build up) the redistribution layers and the redistribution formation layers.

<Step (G)>
Step (G) is a step of forming a solder resist layer on the rewiring layer. The material of the solder resist layer can be any material having insulating properties. Among them, photosensitive resins and thermosetting resins are preferred from the viewpoint of ease of manufacturing the semiconductor chip package. The photosensitive resin composition of the present invention may also be used.

In step (G), bumping processing may be performed to form bumps, if necessary. The bumping processing may be performed using a solder ball, solder plating, or the like. In addition, the formation of via holes in the bumping processing may be performed in the same manner as in step (E).

The method for manufacturing a semiconductor chip package may include step (H) in addition to steps (A) to (G). Step (H) is a step of dicing a plurality of semiconductor chip packages into individual semiconductor chip packages to separate them. There is no particular limitation on the method for dicing the semiconductor chip packages into individual semiconductor chip packages.

[Semiconductor device]
Examples of semiconductor devices in which the above-mentioned semiconductor chip package is mounted include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.).

The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

<Synthesis Example>
[Synthesis Example 1: Synthesis of Polymer A-1]
29.4 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA) was placed in a 2 L separable flask, 500 mL of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature. 45.0 g of 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindan (INDAN) was then added, and the reaction vessel was heated in an oil bath until the internal temperature reached 40°C, followed by polymerization for 20 hours.

Next, 1.12 g of potassium hydroxide was added to the reaction solution and stirred at room temperature, then 8.8 g of ethylene carbonate was added, and at the same time, the reaction vessel was heated in an oil bath until the internal temperature reached 80°C, and stirred for 10 hours. The resulting reaction solution was adjusted to 40°C, and 18.1 g of acrylic acid chloride, 0.5 g of dimethylaminopyridine, and 20 g of triethylamine were added, and stirred for 3 hours.

Then, the resulting reaction solution was dropped into 6 L of ultrapure water to precipitate the polymer, which was then purified. The purified polymer was filtered off and then dried under vacuum at 80°C to obtain 71 g of polymer A-1.

The molecular weight of Polymer A-1 was measured by gel permeation chromatography (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 50,000. The structure of Polymer A-1 is shown below, where n is an integer of 5 to 200.

[Synthesis Example 2: Synthesis of Polymer A-2]
29.4 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA) was placed in a 2 L separable flask, 500 mL of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature. 45.0 g of 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindan (INDAN) was then added, and the reaction vessel was heated in an oil bath until the internal temperature reached 40°C, followed by polymerization for 20 hours.

Next, 1.12 g of potassium hydroxide was added to the reaction solution and stirred at room temperature, then 8.8 g of ethylene carbonate was added, and at the same time, the reaction vessel was heated in an oil bath until the internal temperature reached 80°C, and stirred for 10 hours. The resulting reaction solution was adjusted to 40°C, and 20.6 g of methacrylic acid chloride, 0.5 g of dimethylaminopyridine, and 20 g of triethylamine were added, and stirred for 3 hours.

Then, the resulting reaction solution was dropped into 6 L of ultrapure water to precipitate the polymer, which was then purified. The purified polymer was filtered off and then dried under vacuum at 80°C to obtain 70 g of polymer A-2.

The molecular weight of Polymer A-2 was measured by gel permeation chromatography (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 52,000. The structure of Polymer A-2 is shown below, where n is an integer of 5 to 200.

[Synthesis Example 3: Synthesis of Polymer A-3]
51.8 g of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) was placed in a 2 L separable flask, 500 mL of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature. 45.0 g of 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindan (INDAN) was then added, and the reaction vessel was heated in an oil bath until the internal temperature reached 40° C., and polymerization was carried out for 20 hours.

Next, 1.12 g of potassium hydroxide was added to the reaction solution and stirred at room temperature, then 8.8 g of ethylene carbonate was added, and at the same time, the reaction vessel was heated in an oil bath until the internal temperature reached 80°C, and stirred for 10 hours. The resulting reaction solution was adjusted to 40°C, and 18.1 g of acrylic acid chloride, 0.5 g of dimethylaminopyridine, and 20 g of triethylamine were added, and stirred for 3 hours.

Then, the resulting reaction solution was dropped into 6 L of ultrapure water to precipitate the polymer, which was then purified. The purified polymer was filtered off and then dried under vacuum at 80°C to obtain 90 g of polymer A-3.

The molecular weight of Polymer A-3 was measured by gel permeation chromatography (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 40,000. The structure of Polymer A-3 is shown below, where n is an integer of 5 to 200.

[Synthesis Example 4: Synthesis of Polymer A-4]
51.8 g of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) was placed in a 2 L separable flask, 500 mL of N-methyl-2-pyrrolidone was added, and the mixture was stirred at room temperature. 45.0 g of 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindan (INDAN) was further added, and at the same time, the reaction vessel was heated in an oil bath until the internal temperature reached 40° C., and polymerization was carried out for 20 hours.

Next, 1.12 g of potassium hydroxide was added to the reaction solution and stirred at room temperature, then 8.8 g of ethylene carbonate was added, and at the same time, the reaction vessel was heated in an oil bath until the internal temperature reached 80°C, and stirred for 10 hours. The resulting reaction solution was adjusted to 40°C, and 20.6 g of methacrylic acid chloride, 0.5 g of dimethylaminopyridine, and 20 g of triethylamine were added, and stirred for 3 hours.

Then, the resulting reaction solution was dropped into 6 L of ultrapure water to precipitate the polymer, which was then purified. The purified polymer was filtered and then dried under vacuum at 80°C to obtain 92 g of polymer A-4.

The molecular weight of Polymer A-4 was measured by gel permeation chromatography (standard polystyrene equivalent) and found to have a weight average molecular weight (Mw) of 42,000. The structure of Polymer A-4 is shown below, where n is an integer of 5 to 200.

[Synthesis Example 5: Synthesis of Polymer A-5]
20.0 g (64.5 mmol) of oxydiphthalic dianhydride were suspended in 140 mL of diglyme while removing moisture in a dry reactor equipped with a stirrer, a condenser and a flat-bottom joint equipped with an internal thermometer. 16.8 g (129 mmol) of 2-hydroxyethyl methacrylate, 0.05 g of hydroquinone, 0.05 g of pure water and 10.7 g (135 mmol) of pyridine were added successively and stirred at a temperature of 60° C. for 18 hours. The mixture was then cooled to −20° C., after which 16.1 g (135.5 mmol) of thionyl chloride were added dropwise over 90 minutes. A white precipitate of pyridinium hydrochloride was obtained. The mixture was then warmed to room temperature and stirred for 2 hours, after which 9.7 g (123 mmol) of pyridine and 25 mL of N-methylpyrrolidone (NMP) were added, obtaining a clear solution. To the resulting clear solution, 11.8 g (58.7 mmol) of 4,4'-diaminodiphenyl ether dissolved in 100 mL of NMP was then added dropwise over 1 hour. Then, 5.6 g (17.5 mmol) of methanol and 0.05 g of 3,5-di-tert-butyl-4-hydroxytoluene were added, and the mixture was stirred for 2 hours. The polyimide precursor resin was then precipitated in 4 liters of water, and the water-polyimide precursor resin mixture was stirred at a speed of 500 rpm for 15 minutes. The polyimide precursor resin was obtained by filtration, stirred again in 4 liters of water for 30 minutes, and filtered again. The resulting polyimide precursor resin was then dried under reduced pressure at 45°C for 3 days to obtain polymer A-5.

The resulting polymer A-5 had a weight average molecular weight of 24,800 and a number average molecular weight of 10,500.

[Synthesis Example 6: Synthesis of Polymer A-6]
18.98 g (64.5 mmol) of 4,4'-biphthalic dianhydride was suspended in 140 mL of diglyme while removing moisture in a dry reactor equipped with a stirrer, a condenser and a flat-bottom joint equipped with an internal thermometer. 16.8 g (129 mmol) of 2-hydroxyethyl methacrylate, 0.05 g of hydroquinone, 0.05 g of purified water and 10.7 g (135 mmol) of pyridine were added successively and stirred at a temperature of 60°C for 18 hours. The mixture was then cooled to -20°C, after which 16.1 g (135.5 mmol) of thionyl chloride was added dropwise over 90 minutes. A white precipitate of pyridinium hydrochloride was obtained. The mixture was then warmed to room temperature and stirred for 2 hours, after which 9.7 g (123 mmol) of pyridine and 25 mL of N-methylpyrrolidone (NMP) were added, obtaining a clear solution. To the resulting clear solution, 11.8 g (58.7 mmol) of 4,4'-diaminodiphenyl ether dissolved in 100 mL of NMP was then added dropwise over 1 hour. Then, 5.6 g (17.5 mmol) of methanol and 0.05 g of 3,5-di-tert-butyl-4-hydroxytoluene were added, and the mixture was stirred for 2 hours. The polyimide precursor resin was then precipitated in 4 liters of water, and the water-polyimide precursor resin mixture was stirred at a speed of 500 rpm for 15 minutes. The polyimide precursor resin was obtained by filtration, stirred again in 4 liters of water for 30 minutes, and filtered again. The resulting polyimide precursor resin was then dried under reduced pressure at 45°C for 3 days to obtain polymer A-6. The weight average molecular weight of the resulting polymer A-6 was 24,800, and the number average molecular weight was 10,500.

[Examples 1 to 16 and Comparative Examples 1 to 6]
The reagents shown in Tables 1 and 2 below were mixed in the amounts (parts by mass) shown in each table and stirred using a high-speed rotary mixer to prepare a varnish-like photosensitive resin composition. Solutions (non-volatile content 30%) of the polymers A-1 to A-6 obtained in Synthesis Examples 1 to 6 above were prepared, and these solutions were used for mixing.

Ｉｒｇａｃｕｒｅ ＯＸＥ０１：下記式に示す光重合開始剤（ＢＡＳＦ社製「Ｉｒｇａｃｕｒｅ ＯＸＥ０１」）

ＴＭＰＴ：下記式に示す４官能以下の光架橋剤（新中村化学工業社製「ＴＭＰＴ」）

Ａ－ＴＭＰＴ：下記式に示す４官能以下の光架橋剤（新中村化学工業社製「Ａ－ＴＭＰＴ」）

ＳＲ－２０９：テトラエチレングリコールジメタクリレート（サートマー・ジャパン社製「ＳＲ－２０９」）
ＤＰＨＡ：ジペンタエリスリトールヘキサアクリレート、日本化薬社製、５又は６官能
ＣＮ２３０１：サートマー・ジャパン社製、９官能
ＣＮ２３０４：サートマー・ジャパン社製、１８官能 The abbreviations in the table are as follows:
Polymer A-1: Polymer A-1 produced in Synthesis Example 1.
Polymer A-2: Polymer A-2 produced in Synthesis Example 2.
Polymer A-3: Polymer A-3 produced in Synthesis Example 3.
Polymer A-4: Polymer A-4 produced in Synthesis Example 4.
Polymer A-5: Polymer A-5 produced in Synthesis Example 5.
Polymer A-6: Polymer A-6 produced in Synthesis Example 6.
Irgacure OXE02: Photopolymerization initiator shown in the following formula ("Irgacure OXE02" manufactured by BASF)

Irgacure OXE01: Photopolymerization initiator shown in the following formula ("Irgacure OXE01" manufactured by BASF)

TMPT: a photocrosslinking agent having 4 or less functional groups represented by the following formula ("TMPT" manufactured by Shin-Nakamura Chemical Co., Ltd.)

A-TMPT: a photocrosslinking agent having 4 or less functional groups as shown in the following formula ("A-TMPT" manufactured by Shin-Nakamura Chemical Co., Ltd.)

SR-209: Tetraethylene glycol dimethacrylate ("SR-209" manufactured by Sartomer Japan)
DPHA: Dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., 5 or 6 functional groups CN2301: Manufactured by Sartomer Japan, 9 functional groups CN2304: Manufactured by Sartomer Japan, 18 functional groups

<Preparation of photosensitive film>
A PET film (Toray Industries, Inc., "Lumirror T6AM", thickness 38 μm) was prepared as a support. The photosensitive resin composition prepared in each Example and Comparative Example was uniformly applied to the PET film using a die coater so that the film thickness of the photosensitive resin composition layer after drying was the film thickness shown in the above table, and the film was dried at 80° C. to 120° C. for 6 minutes to form a photosensitive resin composition layer on the PET. Next, a cover film (biaxially oriented polypropylene film, Oji F-Tex Co., Ltd., "MA-411") was placed on the surface of the photosensitive resin composition layer and laminated at 80° C. to produce a photosensitive film having a three-layer structure of support/photosensitive resin composition layer/cover film.

<Evaluation of limiting resolution>
A copper plating was laminated on a silicon wafer with a thickness of 5 μm, and the photosensitive resin composition layer of the photosensitive film was placed on the substrate that had been roughened with a 1% hydrochloric acid aqueous solution for 60 seconds, so that the photosensitive resin composition layer of the photosensitive film was in contact with the surface of the copper layer, and laminated using a vacuum laminator (VP160, manufactured by Nikko Materials Co., Ltd.), forming a laminate in which the copper plating, the photosensitive resin composition layer, and the support were laminated in this order. The pressure bonding conditions were a vacuum drawing time of 30 seconds, a pressure bonding temperature of 60° C., a pressure bonding pressure of 0.7 MPa, and a pressure application time of 30 seconds. After leaving the laminate at room temperature for 30 minutes, the support was peeled off. The laminate from which the support had been peeled off was exposed to ultraviolet light (wavelength 365 nm, intensity 40 mW/cm ² ). The exposure amount was set to a range of 200 mJ/cm ² . The exposure pattern used a quartz glass mask that draws round holes (vias) with opening diameters of 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, and 70 μm. After standing at room temperature for 5 minutes, heat treatment was performed at 100 ° C. for 3 minutes. The entire surface of the photosensitive resin composition layer on the laminate was spray-developed with cyclopentanone at 23 ° C. as a developer at a spray pressure of 0.1 MPa for an optimal time between 30 seconds and 100 seconds, followed by spray rinsing with propylene glycol monomethyl ether acetate at a spray pressure of 0.1 MPa for 30 seconds. The photosensitive resin composition layer was further cured by heat treatment at 170 ° C. for 180 minutes. The diameter of the bottom of the via was observed with an SEM (magnification 1000 times), and the minimum size that can be opened without residue or peeling was defined as the limit opening via. Evaluation was performed according to the following evaluation criteria.
◯: The limit of opening via is 40 μm or less.
△: The limit of the opening via is more than 40 μm and 60 μm or less.
x: There is no via with a limit opening size of 60 μm or less.

Similarly, evaluation was also carried out when the exposure dose was set within the ranges of 300 mJ/cm ² , 400 mJ/cm ² , and 500 mJ/cm ² .

<Evaluation of cross-sectional shape (undercut resistance)>
Regarding the observation of undercut, the limiting opening via was observed with SEM (magnification 2000 times). The radius (μm) of the top and bottom of the cross section of the limiting opening via was measured with SEM, and the difference between the radius of the bottom and the radius of the top (radius of the bottom - radius of the top) was calculated. The calculated value was regarded as the undercut, and was evaluated according to the following evaluation criteria.
◎: No undercut.
◯: Undercut is less than 2 μm.
△: Undercut is 2 μm or more and 4 μm or less.
×: Undercut is more than 4 μm, or a via with a diameter of 70 μm is not opened.

It can be seen that Examples 1 to 16 are excellent in limiting resolution even when the exposure dose is set in the range of 200 mJ/cm ² , 300 mJ/cm ² , 400 mJ/cm ² , and 500 mJ/cm ^2. Therefore, it is shown that Examples 1 to 15 have a wide process window of the exposure dose.

In addition, in Comparative Examples 1 to 6, the limiting resolution and cross-sectional shape could not be measured due to excessive photocrosslinking.

Claims (9)

(A) a polyimide precursor;
(B) a radical generator,
A photosensitive resin composition comprising: (C) a tetrafunctional or lower photocrosslinking agent; and (D) a pentafunctional or higher photocrosslinking agent. The photosensitive resin composition according to claim 1, in which C1/D1 is 0.1 or more and 0.8 or less, where C1 is the number of functional groups per molecule of component (C) and D1 is the number of functional groups per molecule of component (D). The photosensitive resin composition according to claim 1, in which Cw/Dw is 0.1 or more and 5 or less, where Cw is the content of component (C) when the nonvolatile components of the photosensitive resin composition are 100% by mass, and Dw is the content of component (D) when the nonvolatile components of the photosensitive resin composition are 100% by mass. 2. The photosensitive resin composition according to claim 1, wherein the component (A) has a structural unit represented by the following formula (A-1):

(In the formula, each A independently represents a tetravalent organic group, each B independently represents a divalent organic group having an indane skeleton, ^R1 and ^R2 independently represent a hydrogen atom or a monovalent organic group, and n represents an integer of 5 to 200.) The photosensitive resin composition according to claim 1, wherein the component (A) has a structural unit represented by the following formula (A-3):

(In the formula, A1 each independently represents a tetravalent organic group, R ¹¹ and R ¹² each independently represent a hydrogen atom or a monovalent organic group, R ¹³ each independently represent a hydrogen atom or a methyl group, Xa each independently represent a single bond, a group represented by the following formula (1) or a group represented by formula (2), and Xb each independently represent a single bond, a group represented by formula (3) or a group represented by formula (4). m1 represents an integer of 1 to 5, and n1 represents an integer of 5 to 200.)

(In formulas (1) to (4), * represents a bond.) The photosensitive resin composition according to claim 4, wherein R ¹ and R ² in formula (A-1) each independently represent a hydrogen atom or a radical reactive group represented by the following formula (A-2):

(In the formula, R ⁴ to R ⁶ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and p represents an integer of 1 to 10.) A photosensitive film comprising a support and a photosensitive resin composition layer formed on the support and comprising the photosensitive resin composition according to any one of claims 1 to 6. A semiconductor package substrate comprising an insulating layer formed from a cured product of the photosensitive resin composition according to any one of claims 1 to 6. A semiconductor device including the semiconductor package substrate according to claim 8.