WO2024111129A1

WO2024111129A1 - Method for producing polyimide precursor, polyimide precursor, photosensitive resin composition, cured product, method for producing pattern cured product, and electronic component

Info

Publication number: WO2024111129A1
Application number: PCT/JP2022/043634
Authority: WO
Inventors: 祥貴會田; 匡之大江
Original assignee: Ｈｄマイクロシステムズ株式会社
Priority date: 2022-11-25
Filing date: 2022-11-25
Publication date: 2024-05-30

Abstract

The method for producing a polyimide precursor esterifies an isoimide polymer by an alcohol having an unsaturated double bond using an elemental fluorine-free acid or base as a catalyst.

Description

Method for producing polyimide precursor, polyimide precursor, photosensitive resin composition, cured product, method for producing patterned cured product, and electronic component

The present disclosure relates to a method for producing a polyimide precursor, a polyimide precursor, a photosensitive resin composition, a cured product, a method for producing a patterned cured product, and an electronic component.

2. Description of the Related Art Organic materials having high heat resistance, such as polyimide resins, are widely used as protective film materials for semiconductor integrated circuits (LSIs) (see, for example, Japanese Patent Application Laid-Open No. 2003-233634).
Such a protective film (cured film) using a polyimide resin can be obtained by applying a polyimide precursor or a resin composition containing a polyimide precursor onto a substrate, drying the applied resin film, and then heating the resulting film to cure it.

In recent years, from the perspective of preventing environmental pollution, health, and ensuring device reliability, there is a demand for synthesis methods and products that do not use N-methyl-2-pyrrolidone (NMP). Since the general synthesis method for polyimide precursors uses NMP as a solvent, a new synthesis method is desired. In addition, as international regulations on perfluoroalkyl substances and polyfluoroalkyl compounds (PFAS) are also being strengthened, products with a low fluorine content are required.

JP 2016-199662 A

The present disclosure has been made in consideration of the above-mentioned conventional circumstances, and aims to provide a method for producing a polyimide precursor having a low fluorine content, a method for producing a polyimide precursor, a photosensitive resin composition, a cured product, a patterned cured product, and an electronic component.

Specific means for achieving the above object are as follows.
<1> A method for producing a polyimide precursor, comprising esterifying an isoimide polymer with an alcohol having an unsaturated double bond using a fluorine-free acid or base as a catalyst.
<2> The method for producing a polyimide precursor according to <1>, wherein the isoimide polymer is obtained by isoimidizing a polyamic acid polymer in the presence of a condensing agent.
<3> The method for producing a polyimide precursor according to <2>, wherein the condensing agent contains a carbodiimide compound.
<4> The method for producing a polyimide precursor according to any one of <1> to <3>, wherein the fluorine-free acid has a pKa of 1 or less in water at 25° C.
<5> The method for producing a polyimide precursor according to any one of <1> to <3>, wherein the fluorine-free base has a pKa of 7 or more in water at 25° C.
<6> The method for producing a polyimide precursor according to any one of <1> to <5>, wherein the alcohol having an unsaturated double bond includes an alcohol represented by the following general formula (2):

[In formula (2), R ⁸ to R ¹⁰ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and R ^x represents a divalent linking group.]
<7> The method for producing a polyimide precursor according to any one of <1> to <6>, wherein the polyimide precursor contains a compound represented by the following formula (6):

(In general formula (6), X represents a tetravalent organic group, and Y represents a divalent organic group. R ⁶ and R ⁷ each independently represent a hydrogen atom, a group represented by the following general formula (7), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R ⁶ and R ⁷ represents a group represented by the following general formula (7).)

(In formula (7), R ⁸ to R ¹⁰ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and q represents an integer of 1 to 10.)
<8> The method for producing a polyimide precursor according to any one of <1> to <7>, wherein an esterification rate in the esterification is 74% or more.
<9> A polyimide precursor comprising an ester of an isoimide polymer and an alcohol having an unsaturated double bond, the polyimide precursor having a fluorine content of 13 ppm by mass or less.
<10> The polyimide precursor according to <9>, wherein the esterification rate of the esterified product is 74% or more.
<11> A polyimide precursor having an unsaturated double bond, the polyimide precursor having a fluorine content of 13 ppm by mass or less.
<12> The polyimide precursor according to <9> or <10>, wherein the esterification product includes a compound represented by the following formula (6):

(In general formula (6), X represents a tetravalent organic group, and Y represents a divalent organic group. R ⁶ and R ⁷ each independently represent a hydrogen atom, a group represented by the following general formula (7), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R ⁶ and R ⁷ represents a group represented by the following general formula (7).)

(In formula (7), R ⁸ to R ¹⁰ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and q represents an integer of 1 to 10.)
<13> A photosensitive resin composition comprising the polyimide precursor according to any one of <9> to <12>, a polymerizable monomer, and a solvent.
<14> A photosensitive resin composition comprising a polyimide precursor having an unsaturated double bond, a polymerizable monomer, and a solvent, and having a fluorine content of 10 ppm by mass or less.
<15> A step of applying the photosensitive resin composition according to <13> or <14> onto a substrate and drying the composition to form a photosensitive resin film;
a step of pattern-exposing the photosensitive resin film to obtain a resin film;
developing the resin film after the patterned exposure with a developer to obtain a patterned resin film;
and heat-treating the patterned resin film.
<16> A cured product obtained by curing the photosensitive resin composition according to <13> or <14>.
<17> The cured product according to <16>, which is a patterned cured product.
<18> The cured product according to <16> or <17>, which is used as an interlayer insulating film, a cover coat layer, or a surface protective film.
<19> An electronic part comprising the cured product according to any one of <16> to <18>.

The present disclosure provides a method for producing a polyimide precursor having a low fluorine content, a method for producing a polyimide precursor, a photosensitive resin composition, a cured product, a patterned cured product, and an electronic component.

1A to 1C are diagrams illustrating a manufacturing process for an electronic component according to an embodiment of the present disclosure.

Below, the form for implementing this disclosure will be described in detail. However, this disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless specifically stated otherwise. The same applies to numerical values and their ranges, and they do not limit this disclosure.

In the present disclosure, the term "step" includes not only a step that is independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.
In the present disclosure, the numerical range indicated using "to" includes the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple types of corresponding substances. When multiple types of substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In the present disclosure, the terms "layer" and "film" include cases where the layer or film is formed over the entire area when the area in which the layer or film is present is observed, as well as cases where the layer or film is formed over only a portion of the area.
In the present disclosure, the average thickness of a layer or film is defined as the arithmetic mean value of thicknesses measured at five points on the layer or film of interest.
The thickness of the layer or film can be measured using a micrometer or the like. In the present disclosure, when the thickness of the layer or film can be measured directly, it is measured using a micrometer. On the other hand, when the thickness of one layer or the total thickness of multiple layers is measured, it may be measured by observing the cross section of the measurement target using an electron microscope.

<Method of producing polyimide precursor>
The method for producing a polyimide precursor according to the present disclosure is a method for esterifying an isoimide polymer with an alcohol having an unsaturated double bond using a fluorine-free acid or base as a catalyst, which makes it possible to obtain a polyimide precursor having a low fluorine content.

One method for synthesizing a polyimide precursor having an unsaturated double bond is to react a tetracarboxylic dianhydride with an alcohol having an unsaturated double bond in an organic solvent to produce a diester derivative, and then to react the diester derivative with a diamine compound. In this method, NMP is generally used as the organic solvent.

An alternative synthesis method includes an isoimide method in which a tetracarboxylic dianhydride is reacted with a diamine compound to form a polyamic acid polymer, which is then isoimidized in the presence of a condensing agent, and an alcohol having an unsaturated double bond is further added to the isoimidized polymer to effect esterification.
However, it was found that the polyimide precursor obtained by this method has a high fluorine content, and it was found that the cause is due to the acid compound used as a condensing agent. It was also found that the acid compound as a condensing agent not only functions as a condensing agent in the isoimidization step, but also functions as a catalyst in the esterification reaction step. Therefore, it was found that the acid compound remains in the finally obtained polyimide precursor, and as a result, the fluorine content is increased.

Therefore, in the method for synthesizing a polyimide precursor disclosed herein, a fluorine-free acid or base is used as a catalyst in the esterification reaction between an isoimide polymer and an alcohol having an unsaturated double bond. By using a fluorine-free acid or base as a catalyst for the esterification reaction, it is possible to obtain a polyimide precursor with a low fluorine content. In addition, some of the fluorine-free acids or bases can improve the esterification rate compared to conventional catalysts.

(Isoimide polymer)
The isoimide polymer is not particularly limited, and examples thereof include compounds having a structural unit represented by the following formula (6-1).

In the general formula (6-1), X represents a tetravalent organic group, and Y represents a divalent organic group. The isoimide polymer may have a plurality of structural units represented by the general formula (6-1), and X and Y in the plurality of structural units may be the same or different.

In formula (6-1), the tetravalent organic group represented by X preferably has 4 to 25 carbon atoms, more preferably 5 to 13 carbon atoms, and even more preferably 6 to 12 carbon atoms.
The tetravalent organic group represented by X may contain an aromatic ring or an alicyclic ring. Examples of the aromatic ring include aromatic hydrocarbon groups (e.g., aromatic rings having 6 to 20 carbon atoms) and aromatic heterocyclic groups (e.g., heterocyclic rings having 5 to 20 atoms). Examples of the alicyclic ring include a cycloalkane structure having 3 to 8 carbon atoms and a spiro ring structure having 5 to 25 carbon atoms. From the viewpoint of heat resistance, the tetravalent organic group represented by X is preferably an aromatic hydrocarbon group. Examples of the aromatic hydrocarbon group include a benzene ring, a naphthalene ring, and a phenanthrene ring.
When the tetravalent organic group represented by X contains an aromatic ring, each aromatic ring may have a substituent or may be unsubstituted. Examples of the substituent of the aromatic ring include an alkyl group, a fluorine atom, a halogenated alkyl group, a hydroxyl group, and an amino group.
When the tetravalent organic group represented by X contains a benzene ring, the tetravalent organic group represented by X preferably contains one to four benzene rings, more preferably contains one to three benzene rings, and even more preferably contains one or two benzene rings.
When the tetravalent organic group represented by X contains two or more benzene rings, the respective benzene rings may be linked by a single bond, or may be linked by a linking group such as an alkylene group, a halogenated alkylene group, a carbonyl group, a sulfonyl group, an ether bond (-O-), a sulfide bond (-S-), a silylene bond (-Si(R ^A ) ₂ -; each of the two R ^A 's independently represents a hydrogen atom, an alkyl group, or a phenyl group), a siloxane bond (-O-(Si(R ^B ) ₂ -O-) _n ; each of the two R ^B 's independently represents a hydrogen atom, an alkyl group, or a phenyl group, and n represents an integer of 1 or 2 or more), or a composite linking group formed by combining at least two of these linking groups. In addition, the two benzene rings may be linked at two points by at least one of a single bond and a linking group to form a five- or six-membered ring containing a linking group between the two benzene rings.

Specific examples of the tetravalent organic group represented by X include groups represented by the following formulae (A) to (F). Among them, from the viewpoint of obtaining an insulating film excellent in flexibility and further suppressing the occurrence of voids at the bonding interface, a group represented by the following formula (E) is preferred, and in the following formula (E), C is more preferably a group containing an ether bond, and even more preferably an ether bond. The following formula (F) is a structure in which C in the following formula (E) is a single bond.
It should be noted that the present disclosure is not limited to the following specific examples.

In formula (D), A and B are each independently a single bond or a divalent group not conjugated with a benzene ring. However, both A and B cannot be single bonds. Examples of the divalent group not conjugated with a benzene ring include a methylene group, a halogenated methylene group, a halogenated methylmethylene group, a carbonyl group, a sulfonyl group, an ether bond (-O-), a sulfide bond (-S-), a silylene bond (-Si(R ^A ) ₂ -; each of the two R ^A 's independently represents a hydrogen atom, an alkyl group, or a phenyl group). Among these, A and B are each independently preferably a methylene group, a bis(trifluoromethyl)methylene group, a difluoromethylene group, an ether bond, a sulfide bond, or the like, and more preferably an ether bond.

In formula (E), C represents an alkylene group, a halogenated alkylene group, a carbonyl group, a sulfonyl group, an ether bond (-O-), a sulfide bond (-S-), a phenylene group, an ester bond (-O-C(=O)-), a silylene bond (-Si(R ^A ) ₂ -; two R ^A 's each independently represent a hydrogen atom, an alkyl group, or a phenyl group), a siloxane bond (-O-(Si(R ^B ) ₂ -O-) _n ; two R ^B 's each independently represent a hydrogen atom, an alkyl group, or a phenyl group, and n is an integer of 1 or 2 or more), or a divalent group comprising at least two of these. C preferably contains an ether bond, and is preferably an ether bond.
In addition, C may be a structure represented by the following formula (C1).

The alkylene group represented by C in formula (E) is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and even more preferably an alkylene group having 1 or 2 carbon atoms.
Specific examples of the alkylene group represented by C in formula (E) include linear alkylene groups such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group; a methylmethylene group, a methylethylene group, an ethylmethylene group, a dimethylmethylene group, a 1,1-dimethylethylene group, a 1-methyltrimethylene group, a 2-methyltrimethylene group, an ethylethylene group, a 1-methyltetramethylene group, a 2-methyltetramethylene group, a 1-ethyltrimethylene group, a 2-ethyltrimethylene group, a 1,1-dimethyl branched alkylene groups such as ethyltrimethylene group, 1,2-dimethyltrimethylene group, 2,2-dimethyltrimethylene group, 1-methylpentamethylene group, 2-methylpentamethylene group, 3-methylpentamethylene group, 1-ethyltetramethylene group, 2-ethyltetramethylene group, 1,1-dimethyltetramethylene group, 1,2-dimethyltetramethylene group, 2,2-dimethyltetramethylene group, 1,3-dimethyltetramethylene group, 2,3-dimethyltetramethylene group, and 1,4-dimethyltetramethylene group. Among these, a methylene group is preferred.

The halogenated alkylene group represented by C in formula (E) is preferably a halogenated alkylene group having 1 to 10 carbon atoms, more preferably a halogenated alkylene group having 1 to 5 carbon atoms, and even more preferably a halogenated alkylene group having 1 to 3 carbon atoms.
Specific examples of the halogenated alkylene group represented by C in formula (E) include alkylene groups in which at least one hydrogen atom contained in the alkylene group represented by C in the above formula (E) is substituted with a halogen atom such as a fluorine atom or a chlorine atom. Among these, a fluoromethylene group, a difluoromethylene group, a hexafluorodimethylmethylene group, etc. are preferred.

The alkyl group represented by R ^A or R ^B contained in the silylene bond or siloxane bond is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably an alkyl group having 1 or 2 carbon atoms. Specific examples of the alkyl group represented by R ^A or R ^B include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, and the like.

Specific examples of the tetravalent organic group represented by X may be groups represented by the following formulae (J) to (O).

The tetravalent organic group represented by X may contain an alicyclic ring from the viewpoint of adjusting the thermal expansion coefficient when the cured product is formed. When the tetravalent organic group represented by X contains an alicyclic ring, examples of the alicyclic ring include a ring structure that does not contain an unsaturated bond such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a decahydronaphthalene ring, a norbornane ring, an adamantane ring, a bicyclo[2.2.2]octane ring, and a ring structure that contains an unsaturated bond such as a cyclohexene ring. Examples of the alicyclic ring include a spiro ring structure that contains these ring structures. The alicyclic ring may have a substituent such as an oxo group (=O), an alkyl group, a fluorine atom, a halogenated alkyl group, a hydroxyl group, or an amino group, or may be unsubstituted.
A specific example of the tetravalent organic group represented by X having a spiro ring structure is represented by the following formula (P).

In formula (6-1), the divalent organic group represented by Y preferably has 4 to 25 carbon atoms, more preferably 6 to 20 carbon atoms, and even more preferably 12 to 18 carbon atoms.
The skeleton of the divalent organic group represented by Y may be the same as the skeleton of the tetravalent organic group represented by X, and a preferred skeleton of the divalent organic group represented by Y may be the same as the preferred skeleton of the tetravalent organic group represented by X. The skeleton of the divalent organic group represented by Y may be a structure in which two bonding positions of the tetravalent organic group represented by X are substituted with atoms (e.g., hydrogen atoms) or functional groups (e.g., alkyl groups).
The divalent organic group represented by Y may be a divalent aliphatic group or a divalent aromatic group. From the viewpoint of heat resistance, the divalent organic group represented by Y is preferably a divalent aromatic group. Examples of the divalent aromatic group include a divalent aromatic hydrocarbon group (e.g., an aromatic ring having 6 to 20 carbon atoms) and a divalent aromatic heterocyclic group (e.g., a heterocyclic ring having 5 to 20 atoms), and the like, with a divalent aromatic hydrocarbon group being preferred.

Specific examples of the divalent aromatic group represented by Y include groups represented by the following formulae (G) to (H). Among them, from the viewpoint of obtaining an insulating film that is excellent in flexibility and in which the occurrence of voids at the bonding interface is further suppressed, the group represented by the following formula (H) is preferred, and in the following formula (H), D is more preferably a group containing a single bond or an ether bond, and even more preferably a single bond or an ether bond.

In formulae (G) to (H), R each independently represents an alkyl group, an alkoxy group, a hydroxyl group, a halogenated alkyl group, a phenyl group, or a halogen atom, and n each independently represents an integer of 0 to 4.
In formula (H), D represents a single bond, an alkylene group, a halogenated alkylene group, a carbonyl group, a sulfonyl group, an ether bond (-O-), a sulfide bond (-S-), a phenylene group, an ester bond (-O-C(=O)-), a silylene bond (-Si( ^RA ) _2- ; two ^RA 's each independently represent a hydrogen atom, an alkyl group, or a phenyl group), a siloxane bond (-O-(Si( ^RB ) ₂ -O-) _n ; two ^RB 's each independently represent a hydrogen atom, an alkyl group, or a phenyl group, and n represents an integer of 1 or 2 or more), or a divalent group combining at least two of these. D may also be a structure represented by formula (C1) above. Specific examples of D in formula (H) are the same as the specific examples of C in formula (E).
It is preferable that each D in formula (H) independently represents a single bond, an ether bond, a group containing an ether bond and a phenylene group, a group containing an ether bond, a phenylene group and an alkylene group, or the like.

The alkyl group represented by R in formulas (G) to (H) is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably an alkyl group having 1 or 2 carbon atoms.
Specific examples of the alkyl group represented by R in formulae (G) to (H) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and a t-butyl group.

The alkoxy group represented by R in formulas (G) to (H) is preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms, and even more preferably an alkoxy group having 1 or 2 carbon atoms.
Specific examples of the alkoxy group represented by R in formulae (G) to (H) include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, an s-butoxy group, and a t-butoxy group.

The halogenated alkyl group represented by R in Formulae (G) to (H) is preferably a halogenated alkyl group having 1 to 5 carbon atoms, more preferably a halogenated alkyl group having 1 to 3 carbon atoms, and further preferably a halogenated alkyl group having 1 or 2 carbon atoms.
Specific examples of the halogenated alkyl group represented by R in formulas (G) to (H) include alkyl groups in which at least one hydrogen atom contained in the alkyl group represented by R in formulas (G) to (H) is substituted with a halogen atom such as a fluorine atom or a chlorine atom. The halogenated alkyl group may be a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, etc., but preferably does not contain a fluorine atom.

In formulas (G) to (H), n is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

Specific examples of the divalent aliphatic group represented by Y include linear or branched alkylene groups, cycloalkylene groups, and divalent groups having a polyalkylene oxide structure.

The linear or branched alkylene group represented by Y is preferably an alkylene group having 1 to 20 carbon atoms, more preferably an alkylene group having 1 to 15 carbon atoms, and even more preferably an alkylene group having 1 to 10 carbon atoms.
Specific examples of the alkylene group represented by Y include a tetramethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, an undecamethylene group, a dodecamethylene group, a 2-methylpentamethylene group, a 2-methylhexamethylene group, a 2-methylheptamethylene group, a 2-methyloctamethylene group, a 2-methylnonamethylene group, and a 2-methyldecamethylene group.

The cycloalkylene group represented by Y is preferably a cycloalkylene group having 3 to 10 carbon atoms, and more preferably a cycloalkylene group having 3 to 6 carbon atoms.
Specific examples of the cycloalkylene group represented by Y include a cyclopropylene group, a cyclohexylene group, and the like.

The unit structure contained in the divalent group having a polyalkylene oxide structure represented by Y is preferably an alkylene oxide structure having 1 to 10 carbon atoms, more preferably an alkylene oxide structure having 1 to 8 carbon atoms, and even more preferably an alkylene oxide structure having 1 to 4 carbon atoms. Of these, the polyalkylene oxide structure is preferably a polyethylene oxide structure or a polypropylene oxide structure. The alkylene group in the alkylene oxide structure may be linear or branched. The unit structure in the polyalkylene oxide structure may be of one type or two or more types.

The divalent organic group represented by Y may be a divalent group having a polysiloxane structure. Examples of the divalent group having a polysiloxane structure represented by Y include divalent groups having a polysiloxane structure in which a silicon atom in the polysiloxane structure is bonded to a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 18 carbon atoms.
Specific examples of the alkyl group having 1 to 20 carbon atoms bonded to a silicon atom in the polysiloxane structure include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-octyl group, a 2-ethylhexyl group, an n-dodecyl group, etc. Among these, a methyl group is preferable.
The aryl group having 6 to 18 carbon atoms bonded to the silicon atom in the polysiloxane structure may be unsubstituted or substituted with a substituent. Specific examples of the substituent when the aryl group has a substituent include a halogen atom, an alkoxy group, and a hydroxy group. Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a naphthyl group, and a benzyl group. Of these, a phenyl group is preferred.
The alkyl group having 1 to 20 carbon atoms or the aryl group having 6 to 18 carbon atoms in the polysiloxane structure may be of one type or of two or more types.
The silicon atom constituting the divalent group having a polysiloxane structure represented by Y may be bonded to the NH group in general formula (1) via an alkylene group such as a methylene group or an ethylene group, or an arylene group such as a phenylene group.

The group represented by formula (G) is preferably a group represented by the following formula (G'), and the group represented by formula (H) is preferably a group represented by the following formula (H'), formula (H'') or formula (H''').

In formula (H'"), each R independently represents an alkyl group, an alkoxy group, a halogenated alkyl group, a phenyl group, or a halogen atom. R is preferably an alkyl group, and more preferably a methyl group.

The method for producing the isoimide polymer is not particularly limited, but a polyamic acid polymer may be isoimidized in the presence of a condensing agent. The polyamic acid polymer may be obtained by reacting a tetracarboxylic dianhydride with a diamine compound.

The tetracarboxylic dianhydride used as the raw material for isoimide polymers is represented by the following general formula (8):

In the general formula (8), X is the same as X in the general formula (6-1), and specific examples and preferred examples are also the same.
Specific examples of tetracarboxylic dianhydrides include pyromellitic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride (ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 2,3,5,6-pyridine tetracarboxylic dianhydride, 1,4,5,8-naphthalene Tetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, m-terphenyl-3,3',4,4'-tetracarboxylic acid dianhydride, p-terphenyl-3,3',4,4'-tetracarboxylic acid dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis{4'-(2,3-dicarboxyphenoxy)phenyl}propane dianhydride, 2,2-bis{4'-(3,4-dicarboxyphenoxy)phenyl}propane dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis{4'-(2,3-dicarboxyphenoxy)phenyl}propane dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis{4'- (3,4-dicarboxyphenoxy)phenyl}propane dianhydride, 4,4'-oxydiphthalic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, octahydro-3H,3"H-dispiro[[4,7]methanoisobenzofuran-5,1'-cyclopentane-3',5"-[4,7]methanoisobenzofuran]-1,1",2',3,3"(4H,4"H)-pentane (CpODA), and the like.
The tetracarboxylic dianhydrides may be used alone or in combination of two or more kinds.

The diamine compound used as the raw material of the isoimide polymer may be a diamine compound represented by H ₂ N-Y-NH ₂ , where Y is the same as Y in general formula (6-1), and specific examples and preferred examples are also the same.
Specific examples of the diamine compound include 2,2'-dimethylbiphenyl-4,4'-diamine (DMAP), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-difluoro-4,4'-diaminobiphenyl, p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 1,5-diaminonaphthalene, benzidine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, and 2,2'-diaminodiphenyl ether. , 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,4'-diaminodiphenyl sulfone, 2,2'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 2,4'-diaminodiphenyl sulfide, 2,2'-diaminodiphenyl sulfide, o-tolidine, o-tolidine sulfone, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2,6-diisopropylaniline) ), 2,4-diaminomesitylene, 1,5-diaminonaphthalene, 4,4'-benzophenonediamine, bis-{4-(4'-aminophenoxy)phenyl}sulfone, 2,2-bis{4-(4'-aminophenoxy)phenyl}propane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis{4-(3'-aminophenoxy)phenyl}sulfone, 2,2-bis(4-aminophenyl)propane, 9,9-bis(4-aminophenyl)fluorene, 1,3-bis(3-aminophenoxy)benzene, 1 Examples of the diamine compound include 2-methyl-1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 2-methyl-1,5-diaminopentane, 2-methyl-1,6-diaminohexane, 2-methyl-1,7-diaminoheptane, 2-methyl-1,8-diaminooctane, 2-methyl-1,9-diaminononane, 2-methyl-1,10-diaminodecane, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, and diaminopolysiloxane. As the diamine compound, 2,2'-dimethylbiphenyl-4,4'-diamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, and 1,3-bis(3-aminophenoxy)benzene are preferred.
The diamine compounds may be used alone or in combination of two or more kinds.

The condensing agent preferably contains a carbodiimide compound from the viewpoint of not increasing the fluorine content in the polyimide precursor and efficiently producing an isoimide. Examples of the carbodiimide compound as the condensing agent include 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), N,N'-dicyclohexylcarbodiimide (DCC), N,N'-diisopropylcarbodiimide (DIC), and the like. It is preferable to contain at least one selected from the group consisting of EDC, DCC, and DIC, and it is more preferable to contain EDC.
The carbodiimide compounds may be used alone or in combination of two or more kinds.

The condensing agent may contain other condensing agents other than the carbodiimide compound. Examples of the other condensing agents include imidazole compounds, triazine compounds, uronium compounds, and haluronium compounds. The other condensing agents may be used alone or in combination of two or more.
The condensing agent preferably does not contain a fluorine atom.

The content of the carbodiimide compound in the total condensing agent is preferably 30% by mass or more, more preferably 50% by mass or more, and may be 100% by mass.

A reaction scheme for obtaining an isoimide polymer is shown below when a tetracarboxylic dianhydride represented by general formula (8) is used as the tetracarboxylic dianhydride and a diamine compound represented by H ₂ N-Y-NH ₂ is used as the diamine compound. In the scheme, D represents a condensing agent.

The synthesis of the isoimide polymer is preferably carried out in a solvent. The solvent is preferably one that can dissolve the condensing agent, but may be one that does not dissolve the condensing agent. Examples of the solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, dimethoxyimidazolidinone, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylpropionamide, and N,N-dimethylacetoacetamide, and among these, 3-methoxy-N,N-dimethylpropionamide is preferred.

The amount of the solvent used is not particularly limited, and is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, and more preferably 300 parts by mass or more, per 100 parts by mass of the total amount of the tetracarboxylic dianhydride and the diamine compound.

The amount of diamine compound added per mole of tetracarboxylic dianhydride is preferably 0.1 mole to 1.5 moles, more preferably 0.35 mole to 1.25 moles, and even more preferably 0.5 mole to 1.0 mole.

The amount of the condensing agent used is preferably 0.5 to 3.5 moles, more preferably 1.0 to 3.0 moles, and even more preferably 1.5 to 2.5 moles, per mole of tetracarboxylic dianhydride.

The reaction temperature in the isoimidization may be from 0°C to 60°C, although it varies depending on the types of tetracarboxylic dianhydride and diamine compound used as raw materials, and the type of condensing agent.
The reaction time for isoimidization varies depending on the types of tetracarboxylic dianhydride and diamine compound as raw materials, the type of condensing agent, the reaction temperature, etc., but may be 0.5 to 24 hours.

(alcohol)
The alcohol includes an alcohol having an unsaturated double bond. The alcohol having an unsaturated double bond is not particularly limited as long as it is a compound represented by R-OH (R is a group having an unsaturated double bond), and it is more preferable to include an alcohol represented by the following general formula (2). By including a group represented by general formula (2), the transmittance of i-line is high, and a good cured product tends to be formed even when cured at a low temperature of 400°C or less.

In formula (2), R ⁸ to R ¹⁰ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and R ^x represents a divalent linking group.

The carbon number of the aliphatic hydrocarbon group represented by R ⁸ to R ¹⁰ in general formula (2) is 1 to 3, and preferably 1 or 2. Specific examples of the aliphatic hydrocarbon group represented by R ⁸ to R ¹⁰ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, etc., and a methyl group is preferred.

As a combination of R ⁸ to R ¹⁰ in the general formula (2), a combination in which R ⁸ and R ⁹ are hydrogen atoms and R ¹⁰ is a hydrogen atom or a methyl group is preferred.

In general formula (2), R ^x is a divalent linking group, and is preferably a hydrocarbon group having 1 to 10 carbon atoms. Examples of the hydrocarbon group having 1 to 10 carbon atoms include linear or branched alkylene groups.
The number of carbon atoms in R ^x is preferably 1 to 10, more preferably 2 to 5, and further preferably 2 or 3.

The alcohol represented by general formula (2) is preferably an alcohol represented by the following general formula (2'):

R ⁸ to R ¹⁰ in formula (2′) each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms and have the same meaning as R ⁸ to R ¹⁰ in formula (2). q represents an integer of 1 to 10.

In general formula (2'), q is an integer from 1 to 10, preferably an integer from 2 to 5, and more preferably 2 or 3.

The alcohol may be used in combination with other alcohols other than those having an unsaturated double bond. Examples of the other alcohols include alcohols having an aliphatic hydrocarbon group with 1 to 4 carbon atoms, and are preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or t-butanol, and more preferably methanol or ethanol. The other alcohols may be used alone or in combination with two or more types.

(Fluorine-free acids and bases)
A fluorine-free acid or base is used as a catalyst for the esterification reaction between the isoimide polymer and the alcohol having an unsaturated double bond. From the viewpoint of suppressing the conversion reaction to imide and increasing the esterification rate, it is preferable to use an acid that does not contain a fluorine element.

From the viewpoint of further increasing the esterification rate, the fluorine-free acid preferably has a pKa of less than 5, more preferably 1 or less, further preferably 0 or less, and particularly preferably −1 or less. The pKa here is a value in water at 25° C.
The pKa is measured by neutralization titration.

Specific examples of fluorine-free acids include methanesulfonic acid, formic acid, acetic acid, p-toluenesulfonic acid, benzoic acid, and citric acid, with methanesulfonic acid being preferred.
The fluorine-free acids may be used alone or in combination of two or more kinds.

From the viewpoint of further increasing the esterification rate, the fluorine-free base preferably has a pKa of 5 or more, more preferably 7 or more, even more preferably 8 or more, and particularly preferably 10 or more. Here, the pKa is the value in water at 25°C.

Specific examples of the fluorine-free base include pyridine, 1,4-diazabicyclo[2.2.2]octane, and 1,8-diazabicycloundecene, with 1,8-diazabicycloundecene being preferred.
The fluorine-free base may be used alone or in combination of two or more kinds.

(Esterification of isoimide polymer)
The isoimide polymer is esterified with an alcohol having an unsaturated double bond. For example, the reaction scheme when a compound having a structural unit represented by formula (6-1) is used as the isoimide polymer and a compound represented by R-OH (R is a group having an unsaturated double bond) is used as the alcohol having an unsaturated double bond is shown below.

The alcohol used in the esterification of the isoimide polymer includes an alcohol having an unsaturated double bond, and other alcohols may be used in combination. The content of the alcohol having an unsaturated double bond in the total alcohol is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

The total amount of alcohol is preferably 1.5 moles or more, more preferably 1.8 moles or more, and even more preferably 2 moles or more, per mole of isoimide polymer.

The amount of fluorine-free acid or base used as a catalyst is preferably 0.01 moles or more, more preferably 0.1 moles or more, and more preferably 1 mole or more per mole of isoimide polymer.

Esterification may be carried out in a solvent. Examples of the solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, dimethoxyimidazolidinone, and 3-methoxy-N,N-dimethylpropionamide, and among these, 3-methoxy-N,N-dimethylpropionamide is preferred. There is no particular restriction on the amount of the solvent used.

The reaction temperature in the esterification may be from 0°C to 50°C, although it varies depending on the type of alcohol, the type of catalyst, etc.
The reaction time for isoimidization varies depending on the type of alcohol, the type of catalyst, the reaction temperature, etc., but may be 0.5 to 12 hours.

　After esterification, washing may be carried out. Examples of washing liquids include purified water and organic solvents, and examples of organic solvents include alcohols such as methanol and ethanol, and acetone. These may be used alone or in combination of two or more. An example of a combination of two or more types is a mixture of purified water, acetone, methanol, and ethanol.

The synthesis solution obtained by the above reaction is mixed with 2 to 10 times the amount of washing solution, and the synthesis solution and washing solution are stirred and suction filtered. The obtained wet cake is added to 2 to 10 times the amount of washing solution, stirred for 5 to 30 minutes at 50 to 500 rpm, and suction filtered. This operation may be repeated 1 to 5 times. After that, it is dried under reduced pressure at 20°C to 50°C for 1 to 72 hours to obtain a washed polyimide precursor.

(Polyimide precursor)
The polyimide precursor of the present disclosure contains an ester of an isoimide polymer and an alcohol having an unsaturated double bond, and preferably has a fluorine content of 50 ppm by mass or less.

Moreover, the polyimide precursor of the present disclosure is a polyimide precursor having an unsaturated double bond, and the fluorine content is preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, even more preferably 20 ppm by mass or less, and particularly preferably 13 ppm by mass or less.
Moreover, from the viewpoint of production costs, the polyimide precursor of the present disclosure may have a fluorine content of 5 ppm by mass or more, 8 ppm by mass or more, or 10 ppm by mass or more.
The fluorine content in the polyimide precursor can be measured by combustion ion chromatography as described in the examples.

The esterification rate of the polyimide precursor is preferably 74% or more, more preferably 78% or more, and even more preferably 80% or more.
The esterification rate is the ratio (%) of the ester groups formed in the isoimide polymer by reaction with the alcohol to the total of the ester groups formed in the isoimide polymer by reaction with the alcohol and the carboxy groups not reacted with the alcohol.
The esterification rate of the polyimide precursor can be measured by nuclear magnetic resonance (NMR) analysis.

The polyimide precursor includes a polyimide precursor having an unsaturated double bond (hereinafter, may be referred to as an unsaturated polyimide precursor).
The unsaturated double bond may be a carbon-carbon double bond.
The unsaturated polyimide precursor may be, for example, a polyimide precursor having a structural unit represented by the following general formula (6): When the unsaturated polyimide precursor has a structural unit represented by the general formula (6), it tends to have high i-line transmittance and to form a good cured product even when cured at a low temperature of 300° C. or less.

In formula (6), X represents a tetravalent organic group, and Y represents a divalent organic group. ^R6 and ^R7 each independently represent a hydrogen atom, a group represented by formula (7) below, or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of ^R6 and ^R7 represents a group represented by formula (7) below.

In formula (7), R ⁸ to R ¹⁰ each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms; q represents an integer of 1 to 10.

X and Y in the general formula (6) have the same meanings as X and Y in the above general formula (6-1), respectively.
In formula (6), it is preferred that the --COOR ⁶ group and the --CONH-- group are in the ortho position relative to each other, and the --COOR ⁷ group and the --CO-- group are in the ortho position relative to each other.
The number of carbon atoms in the aliphatic hydrocarbon group represented by ^R6 and ^R7 in general formula (6) is 1 to 4, and preferably 1 or 2. Specific examples of the aliphatic hydrocarbon group represented by ^R6 and ^R7 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and the like.

R ⁸ to R ¹⁰ in formula (7) have the same definitions as R ⁸ to R ¹⁰ in formula (2) above.
In the general formula (6), it is preferable that at least one of R ⁶ and R ⁷ is a group represented by the general formula (7), and it is more preferable that both of R ⁶ and R ⁷ are a group represented by the general formula (7).

There is no particular restriction on the molecular weight of the unsaturated polyimide precursor, but the weight average molecular weight is preferably 10,000 to 200,000.
The weight average molecular weight can be measured, for example, by gel permeation chromatography, and can be calculated using a standard polystyrene calibration curve.

<Photosensitive resin composition>
The photosensitive resin composition of the present disclosure contains a polyimide precursor having an unsaturated double bond, a polymerizable monomer, and a solvent. The polyimide precursor having an unsaturated double bond may be a polyimide precursor having an unsaturated double bond obtained by the production method of the present disclosure.

The photosensitive resin composition of the present disclosure preferably has a fluorine content of 30 ppm by mass or less, more preferably 20 ppm by mass or less, and even more preferably 10 ppm by mass or less.
The fluorine content in the photosensitive resin composition can be measured by combustion ion chromatography, as described in the Examples.

The photosensitive resin composition of the present disclosure is preferably a negative type photosensitive resin composition.

(Polyimide precursor)
The polyimide precursor having an unsaturated double bond may be a polyimide precursor having an unsaturated double bond obtained by the manufacturing method of the present disclosure. The unsaturated polyimide precursor may be a polyimide precursor having a structural unit represented by the above general formula (6). The content of the structural unit represented by the following general formula (6) in the unsaturated polyimide precursor is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, based on the total structural units contained in the unsaturated polyimide precursor. The upper limit is not particularly limited, and may be 100 mol%.

The unsaturated polyimide precursor may have a structural unit other than the structural unit represented by general formula (6). Examples of the structural unit other than the structural unit represented by general formula (6) include a structural unit in which R ⁶ and R ⁷ in general formula (6) are each independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, that is, a structural unit in which neither R ⁶ nor R ⁷ in general formula (6) is a group represented by general formula (7).

(Polymerizable Monomer)
The photosensitive resin composition of the present disclosure contains a polymerizable monomer. The polymerizable monomer may be used alone or in combination of two or more. The polymerizable monomer may be a compound having at least one polymerizable unsaturated bond in the molecule, and is preferably a compound having two or more polymerizable unsaturated bonds in the molecule.
Examples of the group containing a polymerizable unsaturated bond include an allyl group, an acryloyloxy group, a methacryloyloxy group, etc. Among these, an acryloyloxy group or a methacryloyloxy group is preferred.

The molecular weight of the polymerizable monomer is preferably 50 to 1000, more preferably 75 to 800, and even more preferably 100 to 500.

The polymerizable monomer is preferably a compound having two acryloyloxy groups or methacryloyloxy groups, and more preferably a compound in which two acryloyloxy groups or methacryloyloxy groups are linked by an aliphatic cyclic skeleton (hereinafter also referred to as an alicyclic monomer), or a compound in which two acryloyloxy groups or methacryloyloxy groups are linked by a linear divalent organic group (hereinafter also referred to as a linear monomer).

Examples of the alicyclic skeleton in the alicyclic monomer include a tricyclodecane skeleton, a cyclohexane skeleton, a cyclopentane skeleton, a 1,3-adamantane skeleton, a hydrogenated bisphenol A skeleton, a hydrogenated bisphenol F skeleton, a hydrogenated bisphenol S skeleton, an isobornyl skeleton, etc. Among these, a tricyclodecane skeleton is preferable.
The alicyclic monomer is preferably a compound represented by formula (1).

In general formula (1), ^R1 and ^R2 are each independently an aliphatic hydrocarbon group having 1 to 4 carbon atoms or a group represented by the following general formula (2): n1 represents 0 or 1, n2 represents an integer of 0 to 2, and n1+n2 is 2 or 3. At least two of the n1 ^R1s and ⁿ² R2s are groups represented by the following general formula (2).

In general formula (2), m is an integer from 1 to 10.

Specific examples of the aliphatic hydrocarbon group having 1 to 4 carbon atoms represented by R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group.

The compound represented by general formula (1) may be a compound represented by the following formula (3):

The compound represented by formula (3) is available, for example, as DCP (tricyclodecane dimethanol dimethacrylate) from Shin-Nakamura Chemical Co., Ltd.

The linear monomer is preferably a compound represented by the following general formula (4) or the following general formula (5).

In general formula (4) or general formula (5), ^R3 's each independently represent a hydrogen atom or a methyl group, ^R4 's represent an alkylene group having 1 to 8 carbon atoms, ^R5 's represent an alkylene group having 1 to 8 carbon atoms, and p's represent an integer of 2 to 5. Multiple ^R3's and ^R5 's may be the same or different.

^R3 in formula (4) or (5) is preferably a methyl group.
Specific examples of the alkylene group having 1 to 8 carbon atoms represented by R ⁴ in the general formula (4) include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, and an octamethylene group.
Specific examples of the alkylene group having 1 to 8 carbon atoms represented by ^R5 in general formula (5) include a methylene group, an ethylene group, a trimethylene group, a methylethylene group, a dimethylmethylene group, a tetramethylene group, a hexamethylene group, and an octamethylene group. Of these, a methylethylene group and an ethylene group are preferred, and an ethylene group is more preferred.
In the general formula (5), p is preferably an integer of 3 or 4.

Specific examples of linear monomers include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate.
Of these, tetraethylene glycol dimethacrylate is preferred.

Other polymerizable monomers besides alicyclic monomers and linear monomers include compounds represented by the following general formulas (13) to (16), styrene, divinylbenzene, 4-vinyltoluene, 4-vinylpyridine, N-vinylpyrrolidone, methylenebisacrylamide, N,N-dimethylacrylamide, and N-methylolacrylamide.

In the formula, R ¹¹¹ and R ¹¹³ to R ¹¹⁵ are each independently a hydrogen atom, an acryloyl group, or a methacryloyl group, L ¹ is each independently a single bond, an alkylene group having 1 to 10 carbon atoms (preferably, a methylene group or an ethylene group), or a -R ¹¹⁶ -(OR ¹¹⁷ ) _n1 - group, and R ¹¹² is an alkyl group having 1 to 10 carbon atoms (preferably, a methyl group or an ethyl group). A is a substituted or unsubstituted heterocycle having 3 to 20 ring atoms. m is an integer of 2 to 6 (preferably, 3 or 4). R ¹¹⁶ is a single bond or an alkylene group having 1 to 10 carbon atoms (preferably, a methylene group or an ethylene group), and R ¹¹⁷ is an alkylene group having 1 to 10 carbon atoms (preferably, a methylene group or an ethylene group). n1 is an integer of 1 to 15. However, at least two (preferably, 3 or 4) R ¹¹¹ are acryloyl groups or methacryloyl groups, at least two (preferably, 2 or 3) R ¹¹³ are acryloyl groups or methacryloyl groups, at least two (preferably, 4, 5 or 6) R ¹¹⁴ are acryloyl groups or methacryloyl groups, and at least two (preferably, 2, 3 or 4) R ¹¹⁵ are acryloyl groups or methacryloyl groups.
A plurality of R ¹¹¹ , R ¹¹³ to R ¹¹⁵ and L ¹ may be the same or different. When a plurality of R ¹¹⁶ and R ¹¹⁷ are present, the plurality of R ¹¹⁶ and R ¹¹⁷ may be the same or different.

In formula (13), R ¹¹¹ is preferably an acryloyl group.
In formula (14), R ¹¹³ is preferably an acryloyl group.
In formula (15), R ¹¹⁴ is preferably an acryloyl group.
In formula (16), R ¹¹⁵ is preferably a hydrogen atom or an acryloyl group.

Examples of the heterocyclic ring having 3 to 20 ring atoms for A include an isocyanuric acid ring and a triazine ring.
Examples of the substituent of the heterocyclic ring having 3 to 20 ring atoms include an alkyl group, a halogenated alkyl group, and a hydroxyl group.

In formula (13), if there are multiple n1s, the sum of the multiple n1s is preferably 25 to 40, and more preferably 30 to 40.

Specific examples of the compounds represented by general formulas (13) to (16) include trimethylolpropane diacrylate, trimethylolpropane triacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, tetramethylolmethane tetraacrylate, tetramethylolmethane tetramethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated isocyanuric acid triacrylate, ethoxylated isocyanuric acid trimethacrylate, acryloyloxyethyl isocyanurate, and methacryloyloxyethyl isocyanurate.

The content of the polymerizable monomer is not particularly limited, and is preferably 1 part by mass to 50 parts by mass, for example, relative to 100 parts by mass of the unsaturated polyimide precursor. From the viewpoint of improving the hydrophobicity of the cured product, it is more preferably 3 parts by mass to 50 parts by mass, and further preferably 5 parts by mass to 35 parts by mass.
When the content of the polymerizable monomer is within the above range, a practical relief pattern is easily obtained and post-development residues in unexposed areas are easily suppressed.

(solvent)
The photosensitive resin composition of the present disclosure contains a solvent.
Examples of the solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, ethyl lactate, propylene glycol monomethyl ether acetate, benzyl acetate, n-butyl acetate, ethoxyethyl propionate, methyl 3-methoxypropionate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphorylamide, tetramethylene sulfone, cyclohexanone, cyclopentanone, diethyl ketone, diisobutyl ketone, methyl amyl ketone, and N-dimethylmorpholine, and are not particularly limited as long as they can sufficiently dissolve each component contained in the photosensitive resin composition. From the viewpoint of international regulations, it is preferable to limit the use of N-methyl-2-pyrrolidone.
As the solvent, a compound represented by the following general formula (11) may be used.

In formula (11), R ⁴¹ to R ⁴³ each independently represent an alkyl group having 1 to 10 carbon atoms.

The alkyl groups represented by R ⁴¹ to R ⁴³ in formula (11) preferably have 1 to 3 carbon atoms, and more preferably 1 or 3 carbon atoms.
Specific examples of the alkyl group having 1 to 10 carbon atoms represented by R ⁴¹ to R ⁴³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.
The compound represented by the general formula (11) is preferably 3-methoxy-N,N-dimethylpropionamide (for example, trade name "KJCMPA-100" (manufactured by KJ Chemicals Co., Ltd.)).

The solvent may be used alone or in combination of two or more kinds.
The content of the solvent is not particularly limited, but is generally 50 parts by mass to 1,000 parts by mass per 100 parts by mass of the total amount of the polyamic acid ester polymer and the polymerizable monomer.

(Photopolymerization initiator)
The photosensitive resin composition of the present disclosure may contain a photopolymerization initiator.
The photopolymerization initiator is not particularly limited as long as it is a compound capable of generating radicals when irradiated with actinic rays, such as ultraviolet rays such as i-rays, visible light, and radiation.

Photopolymerization initiators include oxime compounds, acylphosphine oxide compounds, acyldialkoxymethane compounds, etc.

The photopolymerization initiator preferably contains at least one compound selected from the group consisting of compounds represented by the following general formula (9) and compounds represented by the following general formula (10).

In general formula (9), R ¹¹ is an alkyl group having 1 to 12 carbon atoms, and a1 is an integer of 0 to 5. R ¹² is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. R ¹³ and R ¹⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a phenyl group, or a tolyl group. When a1 is an integer of 2 or more, R ¹¹ may be the same or different.

R ¹¹ is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group. a1 is preferably 1. R ¹² is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an ethyl group. R ¹³ and R ¹⁴ are preferably each independently an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group.

An example of the compound represented by general formula (9) is the compound represented by the following formula (9-1), which is available as "IRGACURE OXE 02" manufactured by BASF Japan Ltd.

In general formula (10), R ¹⁵ is -OH, -COOH, -OCH ₂ OH, -O(CH ₂ ) ₂ OH, -COOCH ₂ OH or -COO(CH ₂ ) ₂ OH, and R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 4 to 10 carbon atoms, a phenyl group or a tolyl group. b1 is an integer of 0 to 5. When b1 is an integer of 2 or more, R ¹⁵ may be the same or different.
R ¹⁵ is preferably —O(CH ₂ ) ₂ OH. b1 is preferably 0 or 1. R ¹⁶ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or a hexyl group. R ¹⁷ is preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group, more preferably a methyl group or a phenyl group.

Examples of the compound represented by general formula (10) include the compound represented by the following formula (10-1), available as "IRGACURE OXE 01" manufactured by BASF Japan Ltd. Also included is the compound represented by the following formula (10-2), available as "NCI-930" manufactured by ADEKA Corporation.

The photopolymerization initiator may be used alone or in combination of two or more types.

The content of the photopolymerization initiator is preferably 0.1 parts by mass to 20 parts by mass, more preferably 0.1 parts by mass to 10 parts by mass, and even more preferably 0.1 parts by mass to 5 parts by mass, relative to 100 parts by mass of the total amount of the polyamic acid ester polymer and the polymerizable monomer.
When the content of the photopolymerization initiator is within the above range, photocrosslinking tends to be uniform in the film thickness direction, making it easier to obtain a practical relief pattern.

(Thermal Polymerization Initiator)
The photosensitive resin composition of the present disclosure may further contain a thermal polymerization initiator from the viewpoint of promoting the polymerization reaction.
As the thermal polymerization initiator, a compound that does not decompose when heated (dried) to remove a solvent during film formation but decomposes when heated during curing to generate radicals and promotes a polymerization reaction between polymerizable monomers or between a polyamic acid ester polymer and a polymerizable monomer is preferred.
The thermal polymerization initiator is preferably a compound having a decomposition point of 110° C. to 200° C., and from the viewpoint of promoting the polymerization reaction at a lower temperature, a compound having a decomposition point of 110° C. to 175° C. is more preferable.

Specific examples of the thermal polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide, peroxyketals such as 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, and 1,1-di(t-butylperoxy)cyclohexane, hydroperoxides such as 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and p-menthane hydroperoxide, dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide, dialkyl peroxides such as dicyclohexane, dicyclohexane, and dicyclohexane. Examples of the peroxyester include diacyl peroxides such as diuroyl peroxide and dibenzoyl peroxide; peroxydicarbonates such as di(4-t-butylcyclohexyl)peroxydicarbonate and di(2-ethylhexyl)peroxydicarbonate; peroxyesters such as t-butylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxybenzoate and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate; and bis(1-phenyl-1-methylethyl)peroxide.
Commercially available products include those under the trade names "Percumyl D", "Percumyl P", and "Percumyl H" (all manufactured by NOF Corporation).

When the photosensitive resin composition of the present disclosure contains a thermal polymerization initiator, the content of the thermal polymerization initiator is preferably 0.1 parts by mass to 20 parts by mass relative to 100 parts by mass of the polyamic acid ester polymer, more preferably 0.2 parts by mass to 20 parts by mass to ensure good flux resistance, and even more preferably 0.3 parts by mass to 10 parts by mass from the viewpoint of suppressing a decrease in solubility due to decomposition during drying.

(Sensitizer)
The photosensitive resin composition of the present disclosure may contain a sensitizer. When the photosensitive resin composition contains a sensitizer, it is possible to maintain both the remaining film rate and good resolution over a wide range of exposure doses.

Sensitizers include Michler's ketone, benzoin, 2-methylbenzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, anthraquinone, methylanthraquinone, 4,4'-bis-(diethylamino)benzophenone, acetophenone, benzophenone, thioxanthone, 1,5-acenaphthene, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, diacetyl benzyl, benzil dimethyl ketal, benzil diethyl ketal, diphenyl disulfide, anthracene, phenanthrenequinone, riboflavin tetrabutylate, acridine orange, erythrosine, phenanthrenequinone, 2-isopropylthioxanthone, 2,6-bis(p-diethylaminobenzylidene)-4-methyl-4-azacyclohexanone, 6-bis(p-dimethylaminobenzylidene)-cyclopentanone, 2,6-bis(p-diethylaminobenzylidene)-4-phenylcyclohexanone, aminostyryl ketone, 3-ketocoumarin compounds, biscoumarin compounds, N-phenylglycine, N-phenyldiethanolamine, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, etc.

Sensitizers may be used alone or in combination of two or more.

When the photosensitive resin composition of the present disclosure contains a sensitizer, the amount of the sensitizer is preferably 0.1 parts by mass to 1.0 parts by mass, and more preferably 0.2 parts by mass to 0.8 parts by mass, per 100 parts by mass of the polyamic acid ester polymer.

(Stabilizer)
The photosensitive resin composition of the present disclosure may contain a stabilizer. When the photosensitive resin composition contains a stabilizer, the storage stability can be improved.

Stabilizers include p-methoxyphenol, diphenyl-p-benzoquinone, benzoquinone, hydroquinone, pyrogallol, phenothiazine, resorcinol, ortho-dinitrobenzene, para-dinitrobenzene, meta-dinitrobenzene, phenanthraquinone, N-phenyl-2-naphthylamine, cupferron, 2,5-toluquinone, tannic acid, parabenzylaminophenol, nitrosamines, and the compound represented by the following formula F1.

Stabilizers may be used alone or in combination of two or more types.

When the photosensitive resin composition of the present disclosure contains a stabilizer, the content of the stabilizer is preferably 0.05 parts by mass to 1.0 parts by mass, and more preferably 0.1 parts by mass to 0.8 parts by mass, per 100 parts by mass of the total amount of the polyamic acid ester polymer and the polymerizable monomer.

(Coupling Agent)
The photosensitive resin composition of the present disclosure may contain a coupling agent.
Usually, in the heat treatment step after development, the functional group portion of the coupling agent reacts with the polyamic acid ester polymer and the siloxane portion reacts with the substrate, thereby further improving the adhesion between the obtained cured product and the substrate.

A preferred coupling agent is a silane coupling agent having a urea bond (-NH-CO-NH-), which can further increase the adhesion to the substrate even when curing is performed at a low temperature of 200° C. or less.
The compound represented by the following general formula (12-1) is more preferred in that it exhibits excellent adhesiveness when cured at low temperatures.

In the general formula (12-1), R ³¹ and R ³² each independently represent an alkyl group having 1 to 5 carbon atoms, a represents an integer of 1 to 10, and b represents an integer of 1 to 3.

Specific examples of compounds represented by general formula (12-1) include ureidomethyltrimethoxysilane, ureidomethyltriethoxysilane, 2-ureidoethyltrimethoxysilane, 2-ureidoethyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 4-ureidobutyltrimethoxysilane, 4-ureidobutyltriethoxysilane, and the like, with 3-ureidopropyltriethoxysilane being preferred.

A silane coupling agent having a hydroxyl group or a glycidyl group may be used as the coupling agent. When a silane coupling agent having a hydroxyl group or a glycidyl group and a silane coupling agent having a urea bond in the molecule are used in combination, the adhesion of the cured product to the substrate during low-temperature curing can be further improved.
Examples of the silane coupling agent having a hydroxy group or a glycidyl group include methylphenylsilanediol, ethylphenylsilanediol, n-propylphenylsilanediol, isopropylphenylsilanediol, n-butylphenylsilanediol, isobutylphenylsilanediol, t-butylphenylsilanediol, diphenylsilanediol, ethylmethylphenylsilanol, n-propylmethylphenylsilanol, isopropylmethylphenylsilanol, n-butylmethylphenylsilanol, isobutylmethylphenylsilanol, t-butylmethylphenylsilanol, ethyl n-propylphenylsilanol, ethylisopropylphenylsilanol, n-butylethylphenylsilanol, isobutylethylphenylsilanol, t-butylethylphenylsilanol, methyldiphenylsilanol, Examples of the compound include nylsilanol, ethyldiphenylsilanol, n-propyldiphenylsilanol, isopropyldiphenylsilanol, n-butyldiphenylsilanol, isobutyldiphenylsilanol, t-butyldiphenylsilanol, phenylsilanetriol, 1,4-bis(trihydroxysilyl)benzene, 1,4-bis(methyldihydroxysilyl)benzene, 1,4-bis(ethyldihydroxysilyl)benzene, 1,4-bis(propyldihydroxysilyl)benzene, 1,4-bis(butyldihydroxysilyl)benzene, 1,4-bis(dimethylhydroxysilyl)benzene, 1,4-bis(diethylhydroxysilyl)benzene, 1,4-bis(dipropylhydroxysilyl)benzene, 1,4-bis(dibutylhydroxysilyl)benzene, and a compound represented by the following general formula (12-2). Among these, in order to further improve the adhesion to the substrate, a compound represented by the following general formula (12-2) is particularly preferred.

In general formula (12-2), R ³³ is a monovalent organic group having a hydroxy group or a glycidyl group, R ³⁴ and R ³⁵ each independently are an alkyl group having 1 to 5 carbon atoms, c is an integer of 1 to 10, and d is an integer of 1 to 3.

Examples of the compound represented by the general formula (12-2) include hydroxymethyltrimethoxysilane, hydroxymethyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, 4-hydroxybutyltrimethoxysilane, 4-hydroxybutyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 4-glycidoxybutyltrimethoxysilane, 4-glycidoxybutyltriethoxysilane, etc.

The silane coupling agent having a hydroxy group or a glycidyl group preferably further contains a nitrogen atom, and a silane coupling agent having an amino group or an amide bond is preferred.
Examples of silane coupling agents having a hydroxy group or a glycidyl group and also having an amino group include bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, bis(2-hydroxyethyl)-3-aminopropyltrimethoxysilane, bis(2-glycidoxyethyl)-3-aminopropyltriethoxysilane, and bis(2-glycidoxyethyl)-3-aminopropyltrimethoxysilane.
Examples of silane coupling agents having a hydroxy group or a glycidyl group and an amide bond include compounds represented by R ³⁶ -(CH ₂ ) _e -CO-NH-(CH ₂ ) _f -Si(OR ³⁷ ) ₃ (R ³⁶ is a hydroxy group or a glycidyl group, e and f each independently are an integer of 1 to 3, and R ³⁷ is a methyl group, an ethyl group, or a propyl group).

Further examples of the coupling agent include compounds represented by R ³⁸ —O—CO—NH—(CH ₂ ) _g Si(OR ³⁹ ) ₃ (R ³⁸ is an alkyl group, g is an integer of 1 to 3, and R ³⁹ is a methyl group, an ethyl group, or a propyl group).

The coupling agent may be used alone or in combination of two or more types.

When the photosensitive resin composition of the present disclosure contains a coupling agent, the content of the coupling agent is preferably 0.1 parts by mass to 20 parts by mass, more preferably 1 part by mass to 10 parts by mass, and even more preferably 3 parts by mass to 10 parts by mass, relative to 100 parts by mass of the polyamic acid ester polymer.

(Surfactants and Leveling Agents)
The photosensitive resin composition of the present disclosure may contain at least one of a surfactant and a leveling agent. When the photosensitive resin composition contains at least one of a surfactant and a leveling agent, the coating property (e.g., suppression of striation (unevenness in film thickness)) and the developability can be improved.

Surfactants or leveling agents include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, etc. Commercially available products include products under the trade names "Megafac (registered trademark) F171", "F173", and "R-08" (all manufactured by DIC Corporation), "Fluorad FC430" and "FC431" (all manufactured by Sumitomo 3M Limited), and "Organosiloxane Polymer KP341", "KBM303", and "KBM803" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The surfactants and leveling agents may be used alone or in combination of two or more.

When the photosensitive resin composition of the present disclosure contains at least one of a surfactant and a leveling agent, the total content of the surfactant and leveling agent is preferably 0.01 parts by mass to 10 parts by mass, more preferably 0.05 parts by mass to 5 parts by mass, and even more preferably 0.05 parts by mass to 3 parts by mass, per 100 parts by mass of the polyamic acid ester polymer.

(anti-rust)
The photosensitive resin composition of the present disclosure may contain a rust inhibitor. When the photosensitive resin composition contains a rust inhibitor, corrosion of copper and copper alloys can be suppressed and discoloration can be prevented.
Examples of the rust inhibitor include triazole derivatives and tetrazole derivatives.
The rust inhibitors may be used alone or in combination of two or more.

When the photosensitive resin composition of the present disclosure contains a rust inhibitor, the content of the rust inhibitor is preferably 0.01 parts by mass to 10 parts by mass, more preferably 0.1 parts by mass to 5 parts by mass, and even more preferably 0.5 parts by mass to 3 parts by mass, per 100 parts by mass of the total amount of the polyamic acid ester polymer and the polymerizable monomer.

<Cured product, its manufacturing method, and electronic component>
The cured product of the present disclosure can be obtained by curing the photosensitive resin composition of the present disclosure.
The cured product of the present disclosure may be used as a patterned cured product or as a non-patterned cured product.
The average thickness of the cured product of the present disclosure is preferably 5 μm to 20 μm.

The method for producing a patterned cured product of the present disclosure includes the steps of applying the photosensitive resin composition of the present disclosure onto a substrate and drying to form a photosensitive resin film, exposing the photosensitive resin film to a pattern to obtain a resin film, developing the resin film after the pattern exposure using a developer to obtain a patterned resin film, and heat-treating the patterned resin film. This allows a patterned cured product to be obtained.

A method for producing a patternless cured product includes, for example, a step of forming a photosensitive resin film of the present disclosure and a step of heat treatment. It may further include a step of exposure to light.

Examples of the substrate include semiconductor substrates such as glass substrates and Si substrates (silicon wafers), metal oxide insulator substrates such as _TiO2 substrates and _SiO2 substrates, silicon nitride substrates, copper substrates, and copper alloy substrates.

There are no particular limitations on the method for applying the photosensitive resin composition disclosed herein, and it can be done using a spinner or the like.

The drying can be carried out using a hot plate, an oven, or the like.
The drying temperature is preferably from 90° C. to 150° C., and from the viewpoint of ensuring the dissolution contrast, it is more preferably from 90° C. to 120° C.
The drying time is preferably from 30 seconds to 5 minutes.
The drying may be carried out two or more times.
This makes it possible to obtain a photosensitive resin film in which the photosensitive resin composition of the present disclosure is formed into a film shape.

The average thickness of the photosensitive resin film is preferably 5 μm to 100 μm, more preferably 6 μm to 50 μm, and even more preferably 7 μm to 30 μm.

The pattern exposure is performed by exposing a predetermined pattern through a photomask, for example.
The actinic rays to be irradiated include ultraviolet rays such as i-rays, visible light, and radiation, and are preferably i-rays.
As the exposure device, a parallel exposure device, an aligner, a projection exposure device, a stepper, a scanner exposure device, or the like can be used.

By developing, a resin film having a pattern formed thereon (patterned resin film) can be obtained. In general, when a negative type photosensitive resin composition is used, the unexposed areas are removed with a developer.
As the developer, a good solvent for the photosensitive resin film can be used alone, or a suitable mixture of a good solvent and a poor solvent can be used.
Examples of the good solvent include N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, α-acetyl-γ-butyrolactone, cyclopentanone, and cyclohexanone.
Examples of the poor solvent include toluene, xylene, methanol, ethanol, isopropanol, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and water.

A surfactant may be added to the developer. The amount added is preferably 0.01 parts by weight to 10 parts by weight, and more preferably 0.1 parts by weight to 5 parts by weight, per 100 parts by weight of the developer.

The development time can be set to, for example, twice the time required for the photosensitive resin film to be immersed and completely dissolved.
The developing time varies depending on the polyamic acid ester polymer used, but is preferably from 10 seconds to 15 minutes, more preferably from 10 seconds to 5 minutes, and from the viewpoint of productivity, further preferably from 20 seconds to 5 minutes.

After development, washing may be carried out with a rinsing liquid.
As the rinse liquid, distilled water, methanol, ethanol, isopropanol, toluene, xylene, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, etc. may be used alone or in appropriate mixture, or in stepwise combination.

By subjecting the patterned resin film to a heat treatment, a patterned cured product can be obtained.
The polyamic acid ester polymer undergoes a dehydration ring-closing reaction during the heat treatment step to become the corresponding polyimide resin.

The temperature of the heat treatment is preferably 250°C or lower, more preferably 120°C to 250°C, and even more preferably 160°C to 200°C.
By keeping the heat treatment temperature within the above range, damage to the substrate or device can be minimized, devices can be produced with a high yield, and energy savings can be achieved in the process.

The heat treatment time is preferably 5 hours or less, and more preferably 30 minutes to 3 hours.
When the heat treatment time is within the above range, the crosslinking reaction or the dehydration ring-closing reaction can proceed sufficiently.
The heat treatment may be performed in air or in an inert atmosphere such as nitrogen, but is preferably performed in a nitrogen atmosphere from the viewpoint of preventing oxidation of the patterned resin film.

Equipment used for heat treatment includes quartz tube furnaces, hot plates, rapid thermal annealing, vertical diffusion furnaces, infrared curing furnaces, electron beam curing furnaces, microwave curing furnaces, etc.

The cured product of the present disclosure can be used as an interlayer insulating film, a cover coat layer, or a surface protection film. Furthermore, the cured product of the present disclosure can be used as a passivation film, a buffer coat film, etc.

The electronic components of the present disclosure include the cured product of the present disclosure. Using one or more selected from the group consisting of the above passivation films, buffer coat films, interlayer insulating films, cover coat layers, and surface protection films, etc., highly reliable electronic components such as semiconductor devices, multilayer wiring boards, various electronic devices, and stacked devices (multi-die fan-out wafer-level packages, etc.) can be manufactured.

An example of a manufacturing process for a semiconductor device, which is an electronic component according to the present disclosure, will be described with reference to the drawings.
FIG. 1 is a manufacturing process diagram of a semiconductor device having a multilayer wiring structure, which is an electronic component according to an embodiment of the present disclosure.
1, a semiconductor substrate 1 such as a Si substrate having circuit elements is covered with a protective film 2 such as a silicon oxide film except for a predetermined portion of the circuit elements, and a first conductor layer 3 is formed on the exposed circuit elements. Then, an interlayer insulating film 4 is formed on the semiconductor substrate 1.

Next, a photosensitive resin layer 5, such as a chlorinated rubber or phenol novolac type, is formed on the interlayer insulating film 4, and windows 6A are provided using known photoetching techniques to expose predetermined portions of the interlayer insulating film 4.

The interlayer insulating film 4 from which the window 6A is exposed is selectively etched to provide a window 6B.
Next, the photosensitive resin layer 5 is removed using an etching solution that will corrode the photosensitive resin layer 5 without corroding the first conductor layer 3 exposed through the windows 6B.

Further, a second conductor layer 7 is formed by using a known photolithography technique, and is electrically connected to the first conductor layer 3 .
When forming a multi-layer wiring structure having three or more layers, the above steps can be repeated to form each layer.

Next, the photosensitive resin composition of the present disclosure is used to open windows 6C by pattern exposure to form a surface protective film 8. The surface protective film 8 protects the second conductor layer 7 from external stress, α-rays, and the like, and the resulting semiconductor device has excellent reliability.
In the above example, the interlayer insulating film 4 can also be formed using the photosensitive resin composition of the present disclosure.

The present disclosure will be explained in more detail below based on experimental examples, examples, and comparative examples. Note that the present disclosure is not limited to the following examples.

[Experimental Example]
Prior to the synthesis of polyimide precursors, which are esters of isoimide polymers and alcohols having unsaturated double bonds, isoimidization and esterification were carried out with monomer compounds as model tests.

(Isoimidization)
Into a flask were placed 325.7 g of 3-methoxy-N,N-dimethylpropionamide ("KJCMPA-100", manufactured by KJ Chemicals Co., Ltd.) and 31.44 g of aniline, and 50.00 g of phthalic anhydride was added thereto to obtain a liquid containing phthalanilic acid.

To the liquid containing phthalanilic acid, 56.9 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), 37.3 g of N,N'-diisopropylcarbodiimide (DIC) or 61.2 g of N,N'-dicyclohexylcarbodiimide (DCC) was added, and the temperature inside the flask was kept at 10°C or lower to obtain a reaction liquid containing an isoimide body.
In another flask, a reaction liquid containing an isoimide compound was obtained in the same manner, except that the temperature inside the flask was kept at 30°C to 35°C.

A 30 ml sample tube was filled with an NMP solution containing 5% by mass of N-butylamine, and approximately 0.5 ml of the reaction solution obtained above was added to it and shaken for about 10 seconds. Five drops of this solution were added to 3 ml of acetonitrile, and the components were analyzed using a high performance liquid chromatograph (HPLC).

(Results of isoimidization)
The results of HPLC analysis showed that an isoimide was obtained regardless of whether EDC, DIC, or DCC was used as the condensation agent. In particular, when EDC was used, the isoimidization rate was 98%, and the isoimid was obtained in high yield. There was no significant difference in the isoimidization rate depending on the reaction temperature for isoimidization.

(Esterification)
2-Hydroxyethyl methacrylate (HEMA) was added to the reaction solution containing the isoimide obtained above, and 0.01, 0.1 or 1 mol eq of any of the catalysts listed below was further added to carry out esterification. The amount of catalyst (mol eq) represents the molar amount of catalyst per mole of the isoimide. HEMA was added so that the amount was 2.2 mol per mole of the isoimide.
The reaction time for the esterification was 1 to 20 minutes.

Catalyst A: Trifluoroacetic anhydride (TFA) (pKa: -0.3)
Catalyst B: methanesulfonic acid (MSA) (pKa: -2.6)
Catalyst C: acetic acid (AA) (pKa: 4.76)
Catalyst D: pyridine (pKa: 5.2)
Catalyst E: 1,4-diazabicyclo[2.2.2]octane (DABCO) (pKa: 8.8)
Catalyst F: 1,8-diazabicycloundecene (DBU) (pKa: 12)

8 ml of acetonitrile was placed in a 9 ml sample tube, and one drop of the reaction solution after esterification was added to it. It was then filtered and the components were analyzed by HPLC.

Esterification products were produced when any of catalysts A to F was used. In particular, catalysts with lower pKa values promoted esterification and suppressed imidization. Therefore, it was found that, from the viewpoint of esterification rate, MSA was preferable among the catalysts tested.
Furthermore, when catalyst A was used, the fluorine content in the esterified product was high.

When the catalyst was 0.01 mol eq, the esterification rate hardly changed even when the reaction time was changed from 1 to 20 minutes. When the catalyst was 0.1 mol eq, the esterification rate increased with increasing reaction time, and remained high for 10 minutes or more. When the catalyst was 1 mol eq, the esterification rate remained at the same high level as when the catalyst was 0.1 mol eq, even with a reaction time of 1 minute.

[Example 1]
3,3',4,4'-biphenylethertetracarboxylic dianhydride (ODPA) was dried in a dryer at 160° C. In addition, 2,2'-dimethylbiphenyl-4,4'-diamine (DMAP) was dried under reduced pressure at 40° C.

70 g of 3-methoxy-N,N-dimethylpropionamide (KJCMPA-100) was placed in a 2-liter round-bottom flask purged with nitrogen, and 0.021 g of benzoquinone, 0.064 g of 1,4-diazabicyclo[2.2.2]octane (DABCO), 12.4 g of dried ODPA, and 1.457 g of 2-hydroxyethyl methacrylate (HEMA) were added and stirred at 30°C to obtain an ODPA (KJCMPA) solution. This solution was used as the PMDA (HEMA) solution.

7.2 g of dried DMAP was dissolved in 56 g of KJCMPA-100 to prepare a DMAP (KJCMPA) solution, which was then added to the above ODPA (KJCMPA) solution and stirred. 14.4 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) was then added and stirred for 1 hour.
Then, 21.2 g of HEMA was added, and 3.8 g (0.05 mol eq) of methanesulfonic acid (MSA) (KJCMPA) prepared by adding MSA to 26.7 g of KJCMPA-100 was further added and stirred to obtain a polyamic acid ester polymer, which is a polyimide precursor.

(Measurement of molecular weight)
The polyamic acid ester polymer thus obtained was measured in terms of standard polystyrene by gel permeation chromatography (GPC) using a solution in which 0.5 mg of the polyamic acid ester polymer was dissolved in 1 mL of a solvent [tetrahydrofuran (THF)/dimethylformamide (DMF)=1/1 (volume ratio)] under the following conditions.
The weight average molecular weight Mw was 22,200 and the dispersity (Mw/Mn) was 1.5.

- GPC measurement conditions -
Measuring device: Shimadzu Corporation SPD-M20A
Pump: Shimadzu Corporation LC-20AD
Column oven: Shimadzu Corporation: CTO-20A
Measurement conditions: Column Gelpack GL-S300MDT-5 x 2 Eluent: THF/DMF = 1/1 (volume ratio)
LiBr (0.03 mol/L), _H3PO4 ( _0.06 mol/L)
Flow rate: 1.0 mL/min, detector: UV 270 nm, column temperature: 40° C.
Standard polystyrene: Tosoh TSKgel standard polystyrene Type F-1, F-4, F-20, F-80, A-2500 to create a calibration curve

--NMR measurement conditions--
Measuring equipment: Bruker Biospin AV400M
Magnetic field strength: 400MHz
Reference material: tetramethylsilane (TMS)
Solvent: dimethyl sulfoxide (DMSO)

(Measurement of Esterification Rate)
The obtained polyamic acid ester polymer was subjected to NMR measurement under the following conditions to calculate the esterification rate (the ratio of ester groups reacted with HEMA to the total of ester groups reacted with HEMA and carboxy groups unreacted with HEMA) which was 83.2 mol%.

(Measurement of Fluorine Content)
The fluorine content of the obtained polyamic acid ester polymer was measured by the following method. The fluorine content was 12.0 mg/kg (ppm by mass). The detection limit of the fluorine content in the following measurement method is 10.0 mg/kg.

The measurement sample was heated and burned using the combustion tube decomposition-ion chromatography method, the generated gas was absorbed in an absorption liquid, and the amount of ions in the absorption liquid was quantified using ion chromatography. The analysis conditions were as follows:

(Sample Combustion Section)
Equipment: AQF-100 (manufactured by Nitto Seiko Analytech Co., Ltd.)
(Ion Chromatography)
Apparatus: ICS-1600 (manufactured by Thermo Fisher Scientific)
Detector: Electrical conductivity detector Column: AS12A
Dissolving solution: 2.7 mmol/L _Na2CO3 _/ 0.3 mmol/ _{L NaHCO3}
Flow rate: 1.2 mL/min Internal standard: tartrate ion (5 mg/kg)

[Example 2]
A polyamic acid ester polymer was synthesized in the same manner as in Example, except that the amount of methanesulfonic acid (MSA) was changed to 7.6 g (1 mol eq).
The weight average molecular weight Mw of the obtained polyamic acid ester polymer was 23,900, the polydispersity (Mw/Mn) was 1.5, the esterification rate was 75.8 mol%, and the fluorine content was 12.4 mg/kg (ppm by mass).

As shown by the results of Examples 1 and 2, a polyimide precursor having a low fluorine content can be obtained according to the method for producing a polyimide precursor of the present disclosure. In addition, since the results of the Examples are consistent with the results of the Experimental Examples, it is presumed that acetic acid, pyridine, 1,4-diazabicyclo[2.2.2]octane, and 1,8-diazabicycloundecene can also be used as a catalyst other than methanesulfonic acid (MSA).
On the other hand, it is found that when trifluoroacetic anhydride, which contains fluorine, is used as a catalyst, the fluorine content in the polyimide precursor as the final product increases. From the viewpoint of the esterification rate, a catalyst with a low pKa is preferable, and methanesulfonic acid (pKa: -2.6) showed a higher esterification rate than trifluoroacetic anhydride (pKa: -0.3).

Reference Signs List 1 Semiconductor substrate 2 Protective film 3 First conductor layer 4 Interlayer insulating film 5 Photosensitive resin layer 6A, 6B, 6C Window 7 Second conductor layer 8 Surface protective film

Claims

A method for producing a polyimide precursor in which a non-fluorine-containing acid or base is used as a catalyst to esterify an isoimide polymer with an alcohol having an unsaturated double bond.
The method for producing a polyimide precursor according to claim 1, wherein the isoimide polymer is obtained by isoimidizing a polyamic acid polymer in the presence of a condensing agent.
The method for producing a polyimide precursor according to claim 2, wherein the condensing agent includes a carbodiimide compound.
The method for producing a polyimide precursor according to any one of claims 1 to 3, wherein the fluorine-free acid has a pKa of 1 or less in water at 25°C.
The method for producing a polyimide precursor according to any one of claims 1 to 3, wherein the fluorine-free base has a pKa of 7 or more in water at 25°C.
The method for producing a polyimide precursor according to any one of claims 1 to 5, wherein the alcohol having an unsaturated double bond includes an alcohol represented by the following general formula (2):

[In formula (2), R 8 to R 10 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and R x represents a divalent linking group.]
The method for producing a polyimide precursor according to any one of claims 1 to 6, wherein the polyimide precursor contains a compound represented by the following formula (6):

(In general formula (6), X represents a tetravalent organic group, and Y represents a divalent organic group. R 6 and R 7 each independently represent a hydrogen atom, a group represented by the following general formula (7), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R 6 and R 7 represents a group represented by the following general formula (7).)

(In formula (7), R 8 to R 10 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and q represents an integer of 1 to 10.)
The method for producing a polyimide precursor according to any one of claims 1 to 7, wherein the esterification rate in the esterification is 74% or more.
A polyimide precursor containing an ester of an isoimide polymer and an alcohol having an unsaturated double bond, and having a fluorine content of 13 ppm by mass or less.
The polyimide precursor according to claim 9, wherein the esterification rate of the esterified product is 74% or more.
A polyimide precursor having an unsaturated double bond and a fluorine content of 13 ppm by mass or less.
The polyimide precursor according to claim 9 or 10, wherein the esterification product comprises a compound represented by the following formula (6):

(In general formula (6), X represents a tetravalent organic group, and Y represents a divalent organic group. R 6 and R 7 each independently represent a hydrogen atom, a group represented by the following general formula (7), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R 6 and R 7 represents a group represented by the following general formula (7).)

(In formula (7), R 8 to R 10 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and q represents an integer of 1 to 10.)
A photosensitive resin composition comprising the polyimide precursor according to any one of claims 9 to 12, a polymerizable monomer, and a solvent.
A photosensitive resin composition containing a polyimide precursor having an unsaturated double bond, a polymerizable monomer, and a solvent, and having a fluorine content of 10 ppm by mass or less.
A step of applying the photosensitive resin composition according to claim 13 or 14 onto a substrate and drying the composition to form a photosensitive resin film;
a step of exposing the photosensitive resin film to a pattern to obtain a resin film;
developing the resin film after the patterned exposure with a developer to obtain a patterned resin film;
and heat-treating the patterned resin film.
A cured product obtained by curing the photosensitive resin composition according to claim 13 or 14.
The cured product according to claim 16, which is a patterned cured product.
The cured product according to claim 16 or 17, which is used as an interlayer insulating film, a cover coat layer, or a surface protective film.
An electronic component comprising the cured product according to any one of claims 16 to 18.