WO2025243482A1 - Resin composition, cured product, method for producing cured product, and electronic component - Google Patents

Abstract

This resin composition contains a polyimide precursor having a polymerizable unsaturated bond, a crosslinking agent having a polymerizable unsaturated bond, and a thermal polymerization initiator. The ratio (B/A) of the number B of polymerizable unsaturated bonds of the crosslinking agent contained in the resin composition to the number A of polymerizable unsaturated bonds of the polyimide precursor contained in the resin composition is 0.2-1.4. The thermal polymerization initiator includes a thermal polymerization initiator with the half-life over one minute of 120°C-190°C.

Description

Resin composition, cured product, method for producing cured product, and electronic component

This disclosure relates to a resin composition, a cured product, a method for producing the cured product, and an electronic component.

2. Description of the Related Art Polyimide resins, which have excellent heat resistance as well as electrical and mechanical properties, are widely used as materials for resin films used as surface protection films, interlayer insulating films, and the like for elements in semiconductor devices.
In recent years, packaging technology for protecting semiconductor elements has become increasingly miniaturized and stacked in order to improve the functionality of electronic devices such as AI (Artificial Intelligence) and smartphones. Furthermore, there is also a demand for miniaturization, stacking, and multi-layering of rewiring layers that constitute semiconductor devices.
Therefore, photosensitive polyimide materials that can form small holes (small opening dimensions) and ensure flatness during multilayering are required as rewiring materials. Furthermore, to improve the performance of electronic devices, components with low heat resistance are sometimes used in semiconductor devices, and there is a demand for reducing the heating temperature (i.e., the curing temperature of photosensitive polyimide materials) during the fabrication of semiconductor devices.
As a resin composition capable of forming a resin film by pattern exposure, a negative photosensitive resin composition containing a polyamide-imide precursor resin having a specific structure, a photopolymerization initiator, and a solvent has been proposed (see, for example, Patent Document 1).

Patent Document 1: JP 2023-153029 A

Generally, polyimide resin precursors have a large cure shrinkage rate because the cured film shrinks due to imidization during curing. Furthermore, since high-temperature heating is required to imidize the polyimide resin precursor, it may be difficult to form a resin film by low-temperature (e.g., 170°C) curing. Furthermore, depending on the combination and compounding ratio of the polyimide resin precursor and the crosslinking agent, the opening size may not be small.
The present disclosure has been made in consideration of the above-described conventional circumstances, and an object of one embodiment of the present disclosure is to provide a resin composition that has a low cure shrinkage rate and is capable of forming a cured product with small opening dimensions. Another embodiment of the present disclosure is to provide a cured product obtained using the resin composition, a method for producing the cured product, and an electronic component.

Specific means for achieving the above object are as follows.
<1> A resin composition containing a polyimide precursor having a polymerizable unsaturated bond, a crosslinking agent having a polymerizable unsaturated bond, and a thermal polymerization initiator,
a ratio (B/A) of the number A of polymerizable unsaturated bonds contained in the polyimide precursor contained in the resin composition to the number B of polymerizable unsaturated bonds contained in the crosslinking agent contained in the resin composition is 0.2 to 1.4;
The resin composition, wherein the thermal polymerization initiator contains a thermal polymerization initiator having a one-minute half-life of 120°C to 190°C.
<2> The resin composition according to <1>, further comprising a photopolymerization initiator.
<3> The resin composition according to <1> or <2>, wherein the polyimide precursor has a structural unit represented by the following general formula (1):

(In general formula (1), X represents a tetravalent organic group, Y represents a divalent organic group, ^R6 and ^R7 each independently represent a hydrogen atom or a monovalent organic group, and at least one of ^R6 and ^R7 has a polymerizable unsaturated bond.)
<4> A cured product of the resin composition according to any one of <1> to <3>.
<5> A method for producing a cured product, comprising: forming a layer of the resin composition according to any one of <1> to <3> on a substrate; and curing the layer of the resin composition.
<6> An electronic part comprising a cured product of the resin composition according to any one of <1> to <3>.

One embodiment of the present disclosure provides a resin composition that can form a cured product with a low cure shrinkage rate and small opening dimensions. Another embodiment of the present disclosure provides a cured product obtained using this resin composition, a method for producing the 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.

Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.
In the present disclosure, constituent elements (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and do not limit the present disclosure.
In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved.
In the present disclosure, numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in stages in this disclosure, 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. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple 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 thickness of a layer or film is determined by measuring the thickness of the layer or film at five points and calculating the arithmetic mean value.
The thickness of a layer or film can be measured using an optical interference film thickness measuring device or the like. In the present disclosure, when the thickness of a layer or film can be measured directly, it is measured using an optical interference film thickness measuring device. On the other hand, when measuring the thickness of a single layer or the total thickness of multiple layers, it may be measured by observing the cross section of the object to be measured using an electron microscope.

In the present disclosure, "(meth)acryloyl" means "acryloyl" and "methacryloyl".
In the present disclosure, when a functional group has a substituent, the number of carbon atoms in the functional group means the total number of carbon atoms including the number of carbon atoms in the substituent.
When describing embodiments with reference to the drawings in this disclosure, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of components in each drawing are conceptual, and the relative size relationships between components are not limited to these.

<Resin composition>
The resin composition of the present disclosure is a resin composition containing a polyimide precursor having a polymerizable unsaturated bond (hereinafter, may be referred to as an "unsaturated polyimide precursor"), a crosslinking agent having a polymerizable unsaturated bond, and a thermal polymerization initiator, wherein the ratio (B/A) of the number A of polymerizable unsaturated bonds possessed by the polyimide precursor contained in the resin composition to the number B of polymerizable unsaturated bonds possessed by the crosslinking agent contained in the resin composition is 0.2 to 1.4, and the thermal polymerization initiator includes a thermal polymerization initiator having a one-minute half-life of 120°C to 190°C.
The resin composition of the present disclosure allows for the formation of a cured product with a low cure shrinkage rate and small opening dimensions. The reason for this is not clear, but is presumed to be as follows.
By setting the ratio (B/A) to 0.2 or more, a crosslinking reaction between the unsaturated polyimide precursors is likely to occur via the crosslinking agent. Therefore, the bond distance between the unsaturated polyimide precursors is likely to be long. Furthermore, a three-dimensional crosslinked structure is likely to be formed between the unsaturated polyimide precursor and the crosslinking agent. As a result, it is presumed that the cure shrinkage of the cured product can be kept low.
By setting the ratio (B/A) to 1.4 or less, the occurrence of a polymerization reaction between crosslinking agents is easily suppressed, so that the crosslinking reaction between crosslinking agents that may cause line thickening and the like is less likely to proceed, and the opening size can be easily adjusted to a desired size, which tends to make it easier to obtain a cured product with small opening sizes.
Furthermore, if the one-minute half-life of the thermal polymerization initiator is 120°C or higher, the crosslinking reaction is less likely to proceed during the drying step when forming a layer of the resin composition on a substrate, and the opening size can be easily adjusted to the desired size, which tends to make it easier to obtain a cured product with small opening sizes.
On the other hand, if the one-minute half-life of the thermal polymerization initiator is 190°C or less, a three-dimensional crosslinked structure is likely to be formed between the unsaturated polyimide precursor and the crosslinking agent during heat curing, which is presumably why the cure shrinkage of the cured product can be kept low.
From the above, it is presumed that the resin composition of the present disclosure makes it possible to form a cured product with a low cure shrinkage rate and small opening dimensions.

The components contained in the resin composition of the present disclosure are described below. The resin composition of the present disclosure is preferably a negative-type photosensitive resin composition (i.e., a resin composition that forms a pattern by removing unexposed areas).

(Unsaturated polyimide precursor)
The resin composition of the present disclosure contains an unsaturated polyimide precursor.
The polymerizable unsaturated bond contained in the unsaturated polyimide precursor may be a carbon-carbon double bond.

The unsaturated polyimide precursor preferably has a structural unit represented by the following general formula (1). This tends to result in a cured product that exhibits high reliability.

In general formula (1), X represents a tetravalent organic group, Y represents a divalent organic group, ^R6 and ^R7 each independently represent a hydrogen atom or a monovalent organic group, and at least one of ^R6 and ^R7 has a polymerizable unsaturated bond.
The unsaturated polyimide precursor may have a plurality of structural units represented by the above general formula (1), and X, Y, ^R6 , and ^R7 in the plurality of structural units may be the same or different.
^R6 and ^R7 are each independently a hydrogen atom or a monovalent organic group, and the combination thereof is not particularly limited as long as at least one of ^R6 and ^R7 has a polymerizable unsaturated bond. As described above, when the unsaturated polyimide precursor has a plurality of structural units represented by the above general formula (1), the combinations of ^R6 and ^R7 in each structural unit may be the same or different.

In general formula (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. Examples of the aromatic ring include aromatic hydrocarbon groups (for example, aromatic rings having 6 to 20 carbon atoms) and aromatic heterocyclic groups (for example, heterocyclic rings having 5 to 20 atoms). 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 on 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 benzene rings may be linked by a single bond, or 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 -; 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 composite linking group combining at least two of these linking groups. Alternatively, the two benzene rings may be linked at two positions 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.

In general formula (1), the —COOR ⁶ group and the —CONH— group are preferably located at the ortho positions relative to each other, and the —COOR ⁷ group and the —CO— group are preferably located at the ortho positions relative to each other.

Specific examples of the tetravalent organic group represented by X include groups represented by the following formulas (A) to (F). Among these, from the viewpoint of obtaining an insulating film that is excellent in flexibility and in which the generation of voids at the bonding interface is further suppressed, a group represented by the following formula (E) is preferred. C in formula (E) is more preferably a group containing an ether bond, and even more preferably an ether bond. Formula (F) below is a structure in which C in formula (E) below 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 that is not conjugated with a benzene ring. However, both A and B cannot be single bonds. Examples of the divalent group that is 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 -; two R ^A 's each independently represent 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, with an ether bond being more preferred.

In formula (E), C 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(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 represents an integer of 1 or 2 or more), or a divalent group combining at least two of these. C is preferably a group containing an ether bond, and is preferably an ether bond.

In general formula (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 have a structure in which two bonding positions in 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 (for example, having 6 to 20 carbon atoms constituting the aromatic ring) and a divalent aromatic heterocyclic group (for example, having 5 to 20 atoms constituting the heterocyclic ring), and a divalent aromatic hydrocarbon group is preferred.

Specific examples of the divalent aromatic group represented by Y include groups represented by the following formulas (G) and (H). Of these, from the viewpoint of obtaining a cured product 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 of these, in the following formula (H), D is more preferably a single bond or a group containing an ether bond, even more preferably a group containing an ether bond, and particularly preferably an ether bond.

In formulas (G) to (H), each R independently represents an alkyl group, an alkoxy group, a halogenated alkyl group, a phenyl group, or a halogen atom, and each n 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(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 represents an integer of 1 or 2 or more), or a divalent group combining at least two of these. Specific examples of D in formula (H) are the same as the specific examples of C in formula (E).
It is preferred 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 Formulas (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 Formulas (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 Formulas (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 even more 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. Among these, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, etc. are preferred.

In formulas (G) to (H), n is preferably each independently 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 and a cyclohexylene group.

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, a polyethylene oxide structure or a polypropylene oxide structure is preferred as the polyalkylene 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. Of these, a methyl group is preferred.
The aryl group having 6 to 18 carbon atoms bonded to the silicon atom in the polysiloxane structure may be unsubstituted or substituted. 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 polysiloxane structure may contain one or more types of alkyl groups having 1 to 20 carbon atoms or aryl groups having 6 to 18 carbon atoms.
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'''). From the viewpoint of having a flexible skeleton and excellent bonding properties, a group represented by the following formula (H') or formula (H'') is more preferred.

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.

In general formula (1), the combination of the tetravalent organic group represented by X and the divalent organic group represented by Y is not particularly limited. Examples of the combination of the tetravalent organic group represented by X and the divalent organic group represented by Y include the following.
A combination in which X is a group represented by formula (E) and Y is a group represented by formula (H) A combination in which X is a group represented by formula (F) and Y is a group represented by formula (H) A combination in which X is a group represented by formula (E) and Y is a group represented by formulas (G) and (H) A combination in which X is a group represented by formulas (A) and (E) and Y is a group represented by formula (H) A combination in which X is a group represented by formulas (E) and (F) and Y is a group represented by formula (H) Among the above combinations, a combination in which X is a group represented by formula (E) and Y is a group represented by formula (H) is preferred, and a combination in which X is a group represented by formula (E), C in formula (E) is an ether bond, and Y is represented by formula (H), D in formula (H) is a single bond is more preferred.

^R6 and ^R7 each independently represent a hydrogen atom or a monovalent organic group, provided that at least one of them has a polymerizable unsaturated bond.
The monovalent organic group is preferably an aliphatic hydrocarbon group having 1 to 4 carbon atoms or an organic group having a polymerizable unsaturated bond, more preferably a group represented by the following general formula (2), an ethyl group, an isobutyl group, or a t-butyl group, and even more preferably contains an aliphatic hydrocarbon group having 1 or 2 carbon atoms or a group represented by the following general formula (2). In this case, at least one of ^R6 and ^R7 is a group represented by general formula (2).
When the monovalent organic group contains an organic group having a polymerizable unsaturated bond, preferably a group represented by the following general formula (2), the i-ray transmittance is high, and a good cured product tends to be formed even when cured at a low temperature of 400° C. or less. Furthermore, when the monovalent organic group contains an organic group having a polymerizable unsaturated bond, preferably a group represented by the following general formula (2), at least a portion of the polymerizable unsaturated bond moiety is eliminated by imidization.

Specific examples of aliphatic hydrocarbon groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, and t-butyl groups, with ethyl, isobutyl, and t-butyl being preferred.

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.

^Rx in general formula (2) 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 even more preferably 2 or 3.

In general formula (1), it is preferable that at least one of ^R6 and ^R7 is a group represented by general formula (2), and it is more preferable that both of ^R6 and ^R7 are groups represented by general formula (2).

When the unsaturated polyimide precursor contains a compound having a structural unit represented by the general formula (1), the proportion of ^R6 and ^R7 , which are groups represented by the general formula (2), to the sum of ^R6 and ^R7 of all structural units contained in the compound is preferably 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more. The upper limit is not particularly limited, and may be 100 mol%.
The above ratio may be more than 0 mol % and less than 60 mol %.

The group represented by general formula (2) is preferably a group represented by the following general formula (2'):

In the general formula (2′), 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.

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 content of the structural unit represented by general formula (1) contained in the compound having the structural unit represented by general formula (1) is preferably 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, based on the total structural units. There is no particular upper limit to the content, and it may be 100 mol%.

The unsaturated polyimide precursor may be synthesized using a tetracarboxylic dianhydride and a diamine compound, in which case, in general formula (1), X corresponds to a residue derived from the tetracarboxylic dianhydride and Y corresponds to a residue derived from the diamine compound.
The unsaturated polyimide precursor may be synthesized using a tetracarboxylic acid instead of a tetracarboxylic dianhydride.

Specific examples of tetracarboxylic dianhydrides include pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenylethertetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, and 1,4,5,8-naphthalenetetracarboxylic acid. dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, m-terphenyl-3,3',4,4'-tetracarboxylic dianhydride, p-terphenyl-3,3',4,4'-tetracarboxylic dianhydride, 1,1,4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-oxydiphthalic anhydride, 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-dicarboxyphenyl)propane 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, cyclopentanone bisspironorbornane tetracarboxylic acid dianhydride, 2,2-bis{4-(4'-phenoxy)phenyl}propane tetracarboxylic acid dianhydride, and the like.
Among these, at least one selected from the group consisting of 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4'-oxydiphthalic anhydride, and 3,3',4,4'-biphenyl tetracarboxylic dianhydride is preferred, at least one selected from the group consisting of pyromellitic dianhydride and 4,4'-oxydiphthalic anhydride is more preferred, and from the viewpoint of bonding at lower temperatures, it is even more preferred to include 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride.
The tetracarboxylic dianhydrides may be used alone or in combination of two or more.

Specific examples of the diamine compound include 2,2'-dimethylbiphenyl-4,4'-diamine, 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, 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 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. Preferred diamine compounds include 2,2'-dimethylbiphenyl-4,4'-diamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, and 1,3-bis(3-aminophenoxy)benzene.
Among these, at least one selected from the group consisting of 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenyl ether, m-phenylenediamine, and 1,3-bis(3-aminophenoxy)benzene is more preferred, and from the viewpoint of having a flexible skeleton and excellent adhesiveness, at least one selected from the group consisting of 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, and 2,2-bis{4-(4'-aminophenoxy)phenyl}propane is even more preferred.
The diamine compounds may be used alone or in combination of two or more.

A compound having a structural unit represented by general formula (1) in which at least one of ^R6 and ^R7 in general formula (1) is a monovalent organic group can be obtained, for example, by the following method (a) or (b).
(a) A tetracarboxylic dianhydride (preferably a tetracarboxylic dianhydride represented by the following general formula (8)) is reacted with a compound represented by R—OH in an organic solvent to form a diester derivative, and then the diester derivative is subjected to a condensation reaction with a diamine compound represented by H ₂ N—Y—NH ₂ .
(b) A tetracarboxylic dianhydride is reacted with a diamine compound represented by H ₂ N-Y-NH ₂ in an organic solvent to obtain a polyamic acid solution, and a compound represented by R—OH is added to the polyamic acid solution and reacted in the organic solvent to introduce an ester group.

Since at least one of R ⁶ and R ⁷ in the general formula (1) has a polymerizable unsaturated bond, at least one of R—OH in which R has a polymerizable unsaturated bond is used.

Here, Y in the diamine compound represented by H ₂ N-Y-NH ₂ is the same as Y in general formula (1), and specific examples and preferred examples are also the same. Furthermore, R in the compound represented by R-OH represents a monovalent organic group, and specific examples and preferred examples are the same as R ⁶ and R ⁷ in general formula (1).
The tetracarboxylic dianhydride represented by general formula (8), the diamine compound represented by H ₂ N-Y-NH ₂ , and the compound represented by R-OH may each be used alone or in combination of two or more.

Examples of the organic solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, dimethoxyimidazolidinone, and 3-methoxy-N,N-dimethylpropanamide, and among these, 3-methoxy-N,N-dimethylpropanamide is preferred.
An unsaturated polyimide precursor may be synthesized by reacting a polyamic acid solution with a dehydration condensation agent together with the compound represented by R—OH. The dehydration condensation agent preferably includes at least one selected from the group consisting of trifluoroacetic anhydride, N,N′-dicyclohexylcarbodiimide (DCC), and 1,3-diisopropylcarbodiimide (DIC).

The above-mentioned compound contained in the unsaturated polyimide precursor can be obtained by reacting a tetracarboxylic dianhydride represented by the following general formula (8) with a compound represented by R—OH to form a diester derivative, then converting it into an acid chloride by reacting it with a chlorinating agent such as thionyl chloride, and then reacting the acid chloride with a diamine compound represented by H ₂ N-Y-NH ₂ .
The above-mentioned compound contained in the unsaturated polyimide precursor can be obtained by reacting a tetracarboxylic dianhydride represented by the following general formula (8) with a compound represented by R—OH to form a diester derivative, and then reacting the diamine compound represented by H ₂ N—Y—NH ₂ with the diester derivative in the presence of a carbodiimide compound.

The above-described compound contained in the unsaturated polyimide precursor can be obtained by reacting a tetracarboxylic dianhydride represented by the following general formula (8) with a diamine compound represented by H ₂ N-Y-NH ₂ to form a polyamic acid, then isoimidizing the polyamic acid in the presence of a dehydrating condensing agent such as trifluoroacetic anhydride, and then reacting it with a compound represented by R-OH. Alternatively, a portion of the tetracarboxylic dianhydride may be reacted in advance with a compound represented by R-OH, and the partially esterified tetracarboxylic dianhydride may be reacted with the diamine compound represented by H ₂ N-Y-NH ₂ .

In general formula (8), X is the same as X in general formula (1), and specific examples and preferred examples are also the same.

The compound represented by R—OH used in the synthesis of the aforementioned compound contained in the unsaturated polyimide precursor may be a compound in which a hydroxy group is bonded to R ^x of the group represented by general formula (2), a compound in which a hydroxy group is bonded to the terminal methylene group of the group represented by general formula (2′), etc. Specific examples of the compound represented by R—OH include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, etc., of which 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate are preferred.

There are no particular restrictions on the molecular weight of the unsaturated polyimide precursor, and for example, the weight average molecular weight is preferably 10,000 to 200,000, more preferably 10,000 to 100,000, and even more preferably 10,000 to 50,000.
The weight average molecular weight of the unsaturated polyimide precursor can be measured, for example, by gel permeation chromatography, and can be calculated using a standard polystyrene calibration curve.

The resin composition of the present disclosure may further contain a dicarboxylic acid. The unsaturated polyimide precursor contained in the resin composition may have a structure obtained by reacting a portion of the amino groups in the unsaturated polyimide precursor with a carboxy group in the dicarboxylic acid. For example, when synthesizing the unsaturated polyimide precursor, a portion of the amino groups of a diamine compound may be reacted with a carboxy group in the dicarboxylic acid.
The dicarboxylic acid may be a dicarboxylic acid having a (meth)acryloyl group, for example, a dicarboxylic acid represented by the following formula: In this case, when synthesizing the unsaturated polyimide precursor, a methacrylic group derived from the dicarboxylic acid can be introduced into the unsaturated polyimide precursor by reacting some of the amino groups of the diamine compound with the carboxyl groups of the dicarboxylic acid.

(Polyimide resin)
The resin composition of the present disclosure may contain a polyimide resin in addition to the unsaturated polyimide precursor. By combining the unsaturated polyimide precursor and the polyimide resin, it is possible to suppress the generation of volatiles due to dehydration cyclization during imide ring formation, and therefore the generation of voids tends to be suppressed. The polyimide resin referred to here refers to a resin having an imide skeleton in all or part of the resin skeleton. It is preferable that the polyimide resin is soluble in the solvent contained in the resin composition.

The polyimide resin is not particularly limited as long as it is a polymeric compound containing multiple structural units containing imide bonds, and it is preferable that it contains, for example, a compound having a structural unit represented by the following general formula (X). This tends to result in a semiconductor device having an insulating film that exhibits high reliability.

In general formula (X), X represents a tetravalent organic group, and Y represents a divalent organic group. Preferred examples of the substituents X and Y in general formula (X) are the same as the preferred examples of the substituents X and Y in general formula (1) described above.

When the resin composition contains an unsaturated polyimide precursor and a polyimide resin, the proportion of the polyimide resin relative to the total of the unsaturated polyimide precursor and the polyimide resin may be 15% by mass to 50% by mass, or may be 10% by mass to 20% by mass.

The resin composition of the present disclosure may contain other resins that do not fall under the category of unsaturated polyimide precursors and polyimide resins as resin components. From the standpoint of heat resistance, examples of other resins include novolac resins, acrylic resins, polyether nitrile resins, polyether sulfone resins, epoxy resins, polyethylene terephthalate resins, polyethylene naphthalate resins, and polyvinyl chloride resins. The other resins may be used alone or in combination of two or more.

In the resin composition, the content of the unsaturated polyimide precursor relative to the total amount of resin components is preferably 50% to 100% by mass, more preferably 70% to 100% by mass, and even more preferably 90% to 100% by mass.

(Crosslinking agent)
The resin composition of the present disclosure contains a crosslinking agent having a polymerizable unsaturated bond. The crosslinking agent may be used alone or in combination of two or more.
The polymerizable unsaturated bond contained in the crosslinking agent may be a carbon-carbon double bond.

Crosslinking agents include compounds that have two or more groups containing polymerizable unsaturated bonds (hereinafter also referred to as functional groups) per molecule. From the standpoint of polymerization reactivity, (meth)acryloyl groups and vinyl groups are preferred as functional groups, with (meth)acryloyl groups being more preferred.

Examples of bifunctional crosslinkers include allyl methacrylate, 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, 1,6-hexanediol dimethacrylate, trimethylolpropane diacrylate, tricyclodecane dimethanol diacrylate, and tricyclodecane dimethanol dimethacrylate.

Examples of trifunctional crosslinking agents include trimethylolpropane triacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, tris-(2-acryloxyethyl) isocyanurate, and tris-(2-methacryloxyethyl) isocyanurate.

Examples of tetrafunctional or higher crosslinking agents include pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, tetramethylolmethane tetraacrylate, tetramethylolmethane tetramethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, tetrakismethan tetrayl tetrakis(methyleneoxyethylene) acrylate, 1,3,4,6-tetraallyl glycoluril, etc.

The content of the crosslinking agent is adjusted so that the ratio (B/A) is in the range of 0.2 to 1.4. The content of the crosslinking agent may be, for example, 1 to 50 parts by weight, 3 to 50 parts by weight, or 5 to 40 parts by weight per 100 parts by weight of the unsaturated polyimide precursor.

(Ratio (B/A))
In the present disclosure, the ratio (B/A) of the number A of polymerizable unsaturated bonds in the unsaturated polyimide precursor contained in the resin composition to the number B of polymerizable unsaturated bonds in the crosslinking agent contained in the resin composition is set to 0.2 to 1.4.
From the viewpoint of suppressing cure shrinkage, the ratio (B/A) is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0.35 or more. From the viewpoint of high-resolution photosensitive characteristics (i.e., the ability to form a pattern with small opening dimensions), the ratio (B/A) is preferably 1.4 or less, more preferably 1.1 or less, and even more preferably 0.8 or less.
In the present disclosure, the number A can be obtained by dividing the content (in grams) of the unsaturated polyimide precursor contained in the resin composition by the formula weight of the structural unit constituting the unsaturated polyimide precursor, and multiplying the result by the number of polymerizable unsaturated bonds contained in the structural unit.
In the present disclosure, the number B can be obtained by dividing the content (in grams) of the crosslinking agent contained in the resin composition by the molecular weight of the crosslinking agent and multiplying the result by the number of polymerizable unsaturated bonds contained in one molecule of the crosslinking agent.

(Thermal polymerization initiator)
The resin composition of the present disclosure contains a thermal polymerization initiator from the viewpoint of improving the physical properties of the cured product. The thermal polymerization initiator may be used alone or in combination of two or more.
The resin composition of the present disclosure contains, as a thermal polymerization initiator, a thermal polymerization initiator having a one-minute half-life of 120°C to 190°C (preferably 130°C to 190°C, more preferably 140°C to 180°C). When two or more types of thermal polymerization initiators are used in combination, the proportion of the thermal polymerization initiators having a one-minute half-life of 120°C to 190°C in the thermal polymerization initiator is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.
The one-minute half-life of a thermal polymerization initiator can be determined by iodometric titration. When using a commercially available thermal polymerization initiator, the value in the manufacturer's catalog can be used.

Specific examples of thermal polymerization initiators include t-butylperoxy 2-ethylhexyl monocarbonate, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, and 2,2'-azobisbutyronitrile.

The content of the thermal polymerization initiator is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

<Other ingredients>
The resin composition of the present disclosure may further include components other than the unsaturated polyimide precursor, crosslinking agent, and thermal polymerization initiator. For example, the resin composition may include a metal chelating agent, a photopolymerization initiator, a stabilizer, a sensitizer, an ultraviolet absorber, a rust inhibitor, an antioxidant, a solvent, etc., which will be described later.

(Metal chelating agent)
The resin composition of the present disclosure may contain a metal chelating agent from the viewpoint of forming a three-dimensional crosslinked structure between the resin composition and the unsaturated polyimide precursor and further reducing the cure shrinkage rate.
Examples of the metal chelating agent contained in the resin composition include a titanium chelating agent, a zirconium chelating agent, and an aluminum chelating agent. The metal chelating agents may be used alone or in combination of two or more. Among these, a titanium chelating agent is preferred as the metal chelating agent from the viewpoint of compatibility with the polyimide and the unsaturated polyimide precursor.

Specific examples of titanium chelating agents include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium dodecylbenzenesulfonate compounds, titanium phosphate complexes, titanium octylene glycolate, and titanium ethylacetoacetate.
Specific examples of the zirconium chelating agent include zirconium tetraacetylacetonate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium tetraacetylacetonate, and zirconium ethylacetoacetate.
Specific examples of the aluminum chelating agent include aluminum trisacetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, and aluminum trisethylacetoacetate.

When the resin composition of the present disclosure contains a metal chelating agent, the content of the metal chelating agent in the resin composition is preferably 0.1 to 10 parts by mass per 100 parts by mass of the unsaturated polyimide precursor.
When the resin composition of the present disclosure contains a metal chelating agent, the content of the metal chelating agent in the resin composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the unsaturated polyimide precursor.
When the resin composition of the present disclosure contains a metal chelating agent, the content of the metal chelating agent in the resin composition is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the unsaturated polyimide precursor.
The proportion of the titanium chelating agent in the metal chelating agent is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. The proportion of the titanium chelating agent in the metal chelating agent may be 100% by mass.

(Photopolymerization initiator)
The resin composition of the present disclosure may contain a photopolymerization initiator. The photopolymerization initiator may be used alone or in combination of two or more.
From the viewpoint of achieving excellent exposure sensitivity and suppressing the occurrence of voids during bonding, it is preferable that the photopolymerization initiator contains an oxime-based photopolymerization initiator.
Specific examples of oxime-based photopolymerization initiators include 1-phenyl-1,2-butanedione-2-(O-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(O-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(O-benzoyl)oxime, and 1,3-diphenylpropanetrione-2-(O-ethoxycarbonyl)oxime. , 1-phenyl-3-ethoxypropanetrione-2-(O-benzoyl)oxime, 1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoyloxime), O-acetyl-1-[6-(2-methylbenzoyl)-9-ethyl-9H-carbazol-3-yl]ethanone oxime, 1-[4-(4-hydroxyethyloxy-phenylthio)phenyl]-1,2-propanedione-2-(O-acetyloxime), and the like.

When the resin composition contains a photopolymerization initiator, the total amount of the photopolymerization initiator is preferably 0.1 to 20 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(Stabilizer)
The resin composition of the present disclosure may contain a stabilizer. The stabilizer may be used alone or in combination of two or more.

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, azo compounds, hindered amine compounds, and hindered phenol compounds.

If the resin composition contains a stabilizer, the stabilizer content is preferably 0.05 to 1.0 part by mass, and more preferably 0.1 to 0.8 part by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(sensitizer)
The resin composition of the present disclosure may contain a sensitizer. The sensitizer may be used alone or in combination of two or more.
Specific examples of the sensitizer include benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone (Michler's ketone), N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, 4,4'-bis(diethylamino)benzophenone, methyl o-benzoylbenzoate, 4-benzoyl-4'-methyldiphenyl ketone, dibenzyl ketone, and benzophenone derivatives such as fluorenone.

If the resin composition contains a sensitizer, the content of the sensitizer is preferably 0.01 to 3 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(ultraviolet absorber)
The resin composition of the present disclosure may contain an ultraviolet absorber. When the resin composition contains an ultraviolet absorber, crosslinking in unexposed areas due to diffuse reflection during exposure tends to be suppressed.

Examples of ultraviolet absorbers include benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, diphenylacrylate compounds, cyanoacrylate compounds, diphenylcyanoacrylate compounds, benzothiazole compounds, azobenzene compounds, polyphenol compounds, and nickel complex compounds. One type of ultraviolet absorber may be used alone, or two or more types may be used in combination.

If the resin composition contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.2 to 2 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(rust inhibitor)
The resin composition of the present disclosure may contain a rust inhibitor from the viewpoint of inhibiting corrosion of metals such as copper and copper alloys and inhibiting discoloration of the metals. Examples of the rust inhibitor include azole compounds and purine derivatives. The rust inhibitor may be used alone or in combination of two or more.

Specific examples of azole compounds include 1H-triazole, 5-methyl-1H-triazole, 5-ethyl-1H-triazole, 4,5-dimethyl-1H-triazole, 5-phenyl-1H-triazole, 4-t-butyl-5-phenyl-1H-triazole, 5-hydroxyphenyl-1H-triazole, phenyltriazole, p-ethoxyphenyltriazole, 5-phenyl-1-(2-dimethylaminoethyl)triazole, 5-benzyl-1H-triazole, hydroxyphenyltriazole, 1,5-dimethyltriazole, 4,5-diethyl-1H-triazole, 1H-benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-benzotriazole, Examples of benzotriazole include 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)benzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, hydroxyphenylbenzotriazole, tolyltriazole, 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, 4-carboxy-1H-benzotriazole, 5-carboxy-1H-benzotriazole, 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, and 1-methyl-1H-tetrazole.

Specific examples of purine derivatives include purine, adenine, guanine, hypoxanthine, xanthine, theobromine, caffeine, uric acid, isoguanine, 2,6-diaminopurine, 9-methyladenine, 2-hydroxyadenine, 2-methyladenine, 1-methyladenine, N-methyladenine, N,N-dimethyladenine, 2-fluoroadenine, 9-(2-hydroxyethyl)adenine, guanine oxime, N-(2-hydroxyethyl)adenine, and 8-amino Examples include adenine, 6-amino-8-phenyl-9H-purine, 1-ethyladenine, 6-ethylaminopurine, 1-benzyladenine, N-methylguanine, 7-(2-hydroxyethyl)guanine, N-(3-chlorophenyl)guanine, N-(3-ethylphenyl)guanine, 2-azaadenine, 5-azaadenine, 8-azaadenine, 8-azaguanine, 8-azapurine, 8-azaxanthine, 8-azahypoxanthine, and derivatives thereof.

If the resin composition contains a rust inhibitor, the content of the rust inhibitor is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(antioxidant)
The resin composition of the present disclosure may contain an antioxidant. The antioxidant may be used alone or in combination of two or more.

Specific examples of the antioxidant include hindered phenol compounds, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, N,N'-bis-3-(3,5-di-tert-butyl-4'-hydroxyphenyl)propionylhexamethylenediamine, 1,3,5-tris(3-hydroxy-4-tert-butyl-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid.
The antioxidants may be used alone or in combination of two or more.

If the resin composition contains an antioxidant, the content of the antioxidant is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

(solvent)
The resin composition of the present disclosure may contain a solvent. The solvent may be used alone or in combination of two or more.
Specific examples of the solvent include ketones such as cyclohexanone, cyclopentanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono-tert-butyl ether acetate, and γ-butyrolactone; and sulfoxides such as dimethyl sulfoxide.

If the resin composition contains a solvent, the content of the solvent is preferably 10 to 10,000 parts by mass, more preferably 50 to 1,000 parts by mass, and even more preferably 100 to 500 parts by mass, per 100 parts by mass of the unsaturated polyimide precursor.

[Main ingredient content]
In the resin composition of the present disclosure, the total content of the unsaturated polyimide precursor, the crosslinking agent, the thermal polymerization initiator, and, optionally, the metal chelating agent, the photopolymerization initiator, the stabilizer, and the solvent may be 80% by mass or more, 90% by mass or more, or 95% by mass or more.

<Cured product>
The cured product of the present disclosure can be obtained by curing the resin composition of the present disclosure.
When the resin composition of the present disclosure has photosensitivity, the cured product of the present disclosure can be obtained by exposing the resin composition to light and then heat-treating it.
Examples of a method for imparting photosensitivity to a resin composition include a method in which a photocurable component such as a photopolymerization initiator is added to the resin composition.
The cured product of the present disclosure can be suitably used as a patterned cured product.
The average thickness of the cured product is preferably 5 μm to 20 μm.

<Method of producing cured product>
A method for producing a cured product of the present disclosure includes the steps of forming a layer of the resin composition of the present disclosure on a substrate and curing the layer of the resin composition.

There are no particular restrictions on the method for forming a layer of the resin composition (hereinafter also referred to as the resin composition layer) on the substrate. For example, the resin composition may be applied to the substrate using a spinner or the like, and then dried using a hot plate, oven, or the like.

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, copper alloy substrates, etc. The surface of the substrate on which the resin composition layer is formed may be made of two or more different materials.

The average thickness of the resin composition layer formed on the substrate is preferably 5 μm to 100 μm, more preferably 6 μm to 50 μm, and even more preferably 7 μm to 30 μm.

The method for curing the resin composition layer formed on the substrate is not particularly limited.
When the resin composition has photosensitivity, the resin composition layer may be cured by exposure (and, if necessary, heat treatment after exposure).
The exposure may be carried out by pattern exposure (a method of carrying out exposure in a pattern consisting of exposed and unexposed areas).
The pattern exposure is carried out by exposing a predetermined pattern through a photomask, for example.
Examples of actinic rays used for exposure include ultraviolet rays such as i-rays, visible light, and radioactive rays, with i-rays being preferred.
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.

The exposed resin composition layer is developed to obtain a patterned resin film (patterned resin film). Generally, when a negative photosensitive resin composition is used, the unexposed areas are removed with a developer.
As the developer, a good solvent for the resin film can be used alone, or a suitable mixture of a good solvent and a poor solvent can be used. After development, the patterned resin film can be washed with a rinse liquid.
Examples of good solvents include N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, α-acetyl-γ-butyrolactone, cyclopentanone, and cyclohexanone.
Examples of poor solvents include toluene, xylene, methanol, ethanol, isopropanol, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and water.

The developed resin film may be subjected to a heat treatment (post-baking) to obtain a patterned cured product.
By carrying out the heat treatment, for example, the unsaturated polyimide precursor contained in the resin film after development undergoes a dehydration ring-closing reaction to become a polyimide resin.

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

The heat treatment time is preferably 5 hours or less, and more preferably 30 minutes to 3 hours.
The heat treatment may be carried out in air or in an inert atmosphere such as nitrogen, but is preferably carried out 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 furnaces, vertical diffusion furnaces, infrared curing furnaces, electron beam curing furnaces, and microwave curing furnaces.

The cured product of the present disclosure can be used, for example, as a resin film.
Specific examples of the resin film include a passivation film, a buffer coat film, an interlayer insulating film, a cover coat film, and a surface protection film.

<Electronic Components>
The electronic component of the present disclosure includes the cured product of the present disclosure described above.
The electronic component includes, for example, the cured product of the present disclosure as a resin film.
Specific examples of electronic components include semiconductor devices, various electronic devices, and stacked devices (such as multi-die fan-out wafer level packages).
In the electronic component, the member in contact with the cured product of the present disclosure may be made of two or more materials (for example, silicon and metal).

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 with 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 predetermined portions 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 resin, is formed on the interlayer insulating film 4, and windows 6A are created 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 corrodes the photosensitive resin layer 5 without corroding the first conductor layer 3 exposed through the window 6B.

Furthermore, 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 multilayer wiring structure of three or more layers, the above steps can be repeated to form each layer.

Next, the 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, alpha 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 resin composition of the present disclosure.

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

(Synthesis of Unsaturated Polyimide Precursor A-1)
A 2-L separable flask was charged with 380 g of N-methyl-2-pyrrolidone (NMP, Mitsubishi Chemical Corporation), and 47.08 g (152 mmol) of 4,4'-oxydiphthalic anhydride (ODPA, Manac Corporation) was added and dissolved while stirring. Furthermore, 0.24 g (2.1 mmol) of DABCO (1,4-diazabicyclo[2.2.2]octane, Fujifilm Wako Pure Chemical Corporation) was added and dissolved, and 5.54 g (42.6 mmol) of 2-hydroxyethyl methacrylate (HEMA, Fujifilm Wako Pure Chemical Corporation) was added. This mixture was stirred at 30°C for 1 hour to obtain a reaction solution.

Separately, 27.4 g (129 mmol) of 2,2'-dimethylbiphenyl-4,4'-diamine (DMAP, Wakayama Seika Kogyo Co., Ltd.) was dissolved in 145 g of NMP to prepare a DMAP solution.
The DMAP solution was added dropwise while stirring the reaction solution at 35°C, and then stirred at 30°C for 3 hours. Next, 73.1 g (348 mmol) of TFAA (trifluoroacetic anhydride, Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise at 30°C. After stirring at 45°C for 2 hours, 0.08 g (0.74 mmol) of BQ (benzoquinone, Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and 40.4 g (310 mmol) of HEMA was added dropwise. After stirring for 15 hours, the mixture was cooled to room temperature. The reaction solution was poured into purified water, and the precipitate was collected. The collected precipitate was washed with purified water and then dried under reduced pressure to obtain a polyimide precursor having a polymerizable unsaturated bond.
The weight average molecular weight (Mw) of the obtained polyimide precursor was 47,000.

The weight-average molecular weight of the polyimide precursor was calculated by gel permeation chromatography (GPC) using a calibration curve based on TSKgel standard polystyrene (Tosoh Corporation). The equipment and conditions are shown below. The measurement sample was prepared by dissolving 2 mg of the sample in 1 mL of eluent (tetrahydrofuran (THF)/dimethylformamide (DMF) = 1/1 (v/v)) and then filtering through a PTFE membrane filter with a pore size of 1 μm.
Equipment: Shimadzu Corporation, Prominence
Column: Resonac Co., Ltd., Gelpak GL S300MDT-5
Eluent: THF/DMF = 1/1 (v/v), lithium bromide 0.03 mol/L, phosphoric acid 0.06 mol/L
・Flow rate: 1.0mL/min
・Measurement wavelength: 270nm
・Injection volume: 10μL

(Synthesis of Unsaturated Polyimide Precursor A-2)
Unsaturated polyimide precursor A-2 was synthesized in the same manner as in the synthesis of unsaturated polyimide precursor A-1, except that the amount of TFAA was changed to 65.6 g (312 mmol). The Mw of unsaturated polyimide precursor A-2 was 40,000.

(Synthesis of Unsaturated Polyimide Precursor A-3)
Unsaturated Polyimide Precursor A-3 was synthesized in the same manner as Unsaturated Polyimide Precursor A-1, except that the amount of TFAA was changed to 55.5 g (264 mmol). The Mw of Unsaturated Polyimide Precursor A-3 was 30,000.

(Synthesis of Unsaturated Polyimide Precursor A-4)
Unsaturated Polyimide Precursor A-4 was synthesized in the same manner as Unsaturated Polyimide Precursor A-1, except that the amount of DMAP was changed to 24.2 g (114 mmol). The Mw of Unsaturated Polyimide Precursor A-4 was 15,000.

(Synthesis of Unsaturated Polyimide Precursor A-5)
Unsaturated Polyimide Precursor A-5 was synthesized in the same manner as Unsaturated Polyimide Precursor A-1, except that DMAP was replaced with 22.8 g (114 mmol) of 4,4-diaminodiphenyl ether (ODA). The Mw of Unsaturated Polyimide Precursor A-5 was 34,000.

(Preparation of Resin Composition)
Resin compositions of Examples 1 to 23 and Comparative Examples 1 to 7 were prepared using the components and blending amounts shown in Tables 1 and 2. Specifically, a mixture of the components was kneaded overnight at room temperature (25°C) in a general solvent-resistant container, and then pressure filtered using a filter with 0.2 μm pores to obtain a resin composition.
The units of the amounts of the components in Tables 1 and 2 are parts by mass. Furthermore, the numbers A and B were determined according to the method described above, and the ratio (B/A) was calculated. The results are shown in Tables 1 and 2.

The components in Tables 1 and 2 are as follows.
GBL: γ-butyrolactone Crosslinker 1: Triethylene glycol dimethacrylate Crosslinker 2: Tricyclodecane dimethanol diacrylate Crosslinker 3: Tris-(2-acryloxyethyl) isocyanurate Crosslinker 4: Ethoxylated pentaerythritol tetraacrylate Crosslinker 5: 1,3,4,6-tetraallyl glycoluril Thermal polymerization initiator 1: Dicumyl peroxide (one minute half-life: 175°C)
Thermal polymerization initiator 2: di(2-t-butylperoxyisopropyl)benzene (one minute half-life: 175°C)
Thermal polymerization initiator 3: t-butylperoxy 2-ethylhexyl monocarbonate (one minute half-life: 161°C)
Thermal polymerization initiator 4: t-hexyl peroxypivalate (one minute half-life: 110°C)
Thermal polymerization initiator 5: p-menthane hydroperoxide (one minute half-life: 200°C)
Photopolymerization initiator: 1-[4-(phenylthio)phenyl]octane-1,2-dione=2-(O-benzoyloxime)
Metal chelating agent: titanium diisopropoxybis(ethyl acetoacetate)

(Cure shrinkage evaluation)
The obtained resin composition was spin-coated onto a 6-inch silicon wafer using a coating device Act8 (manufactured by Tokyo Electron Limited), dried at 100°C for 120 seconds, and then dried (pre-baked) at 110°C for 120 seconds to form a resin film with a dry thickness of 10 μm. The rotation conditions for spin coating were a fixed rotation time of 30 seconds, and the rotation speed was adjusted so that the dry film thickness would be 10 μm. In this evaluation, the rotation speed was in the range of 1000 rpm to 3000 rpm.
The resulting resin film was immersed in cyclopentanone, and the developing time was set to 1.2 times the time required for the resin film to completely dissolve.
In addition, a resin film was prepared in the same manner as above, and the obtained resin film was exposed to i-rays of 100 mJ/cm ² to 1100 mJ/cm ² at an exposure dose of 100 mJ/cm ² increments using an i-ray stepper FPA-3000iW (manufactured by Canon Inc.).
The exposed resin film was paddle-developed with Act8 in cyclopentanone for the above-mentioned development time, followed by rinsing with propylene glycol monomethyl ether acetate (PGMEA) to obtain a resin film. The development time was set to 1.2 times the time required for the resin film to completely dissolve when immersed in cyclopentanone without exposure. The resin film was then heat-treated at 170°C for 2 hours to obtain a cured film. The cure shrinkage at an exposure dose of 500 mJ/ ^cm2 was calculated using the following formula. The results are shown in Tables 1 and 2.
Curing shrinkage rate (%)=(1-(film thickness after curing)/(film thickness after development))×100
The film thickness was measured using an optical interference film thickness measuring device (VM-2200, manufactured by SCREEN Co., Ltd.) at five randomly selected locations.

(Opening dimension evaluation)
A resin film was prepared in the same manner as in the evaluation of cure shrinkage rate, and the obtained resin film was irradiated with 500 mJ/ ^cm2 of i-rays using an i-ray stepper FPA-3000iW (manufactured by Canon Inc.) through a photomask having an opening diameter of 100 μm to 1 μm.
The exposed resin film was puddle-developed with Act8 and cyclopentanone for the above-mentioned development time, followed by rinsing with propylene glycol monomethyl ether acetate (PGMEA) to obtain a resin film with a desired pattern. The diameter of the smallest hole that could be patterned without residue was taken as the resolution. The results are shown in Tables 1 and 2.

The evaluation results shown in Tables 1 and 2 reveal that the resin compositions of the examples, which have a ratio (B/A) in the range of 0.2 to 1.4 and contain a thermal polymerization initiator with a one-minute half-life of 120°C to 190°C, can form cured products with low cure shrinkage and small opening dimensions.
On the other hand, the resin compositions of Comparative Examples 1 and 7, which did not contain a thermal polymerization initiator, had large cure shrinkage rates in the cured products.
Furthermore, the resin composition of Comparative Example 2, in which the ratio (B/A) was less than 0.2, had a large cure shrinkage rate of the cured product.
Furthermore, it was difficult to reduce the opening size of the resin composition of Comparative Example 3, which contained a thermal polymerization initiator with a one-minute half-life of less than 120°C.
Furthermore, the resin composition of Comparative Example 4, which contained a thermal polymerization initiator with a one-minute half-life exceeding 190° C., had a large cure shrinkage rate of the cured product.
In addition, it was difficult to reduce the opening size in the resin compositions of Comparative Examples 5 and 6, in which the ratio (B/A) exceeded 1.4.

Claims (6)

A resin composition containing a polyimide precursor having a polymerizable unsaturated bond, a crosslinking agent having a polymerizable unsaturated bond, and a thermal polymerization initiator,
a ratio (B/A) of the number A of polymerizable unsaturated bonds contained in the polyimide precursor contained in the resin composition to the number B of polymerizable unsaturated bonds contained in the crosslinking agent contained in the resin composition is 0.2 to 1.4;
The resin composition, wherein the thermal polymerization initiator contains a thermal polymerization initiator having a one-minute half-life of 120°C to 190°C. The resin composition according to claim 1, further comprising a photopolymerization initiator. The resin composition according to claim 1, wherein the polyimide precursor has a structural unit represented by the following general formula (1):

(In general formula (1), X represents a tetravalent organic group, Y represents a divalent organic group, ^R6 and ^R7 each independently represent a hydrogen atom or a monovalent organic group, and at least one of ^R6 and ^R7 has a polymerizable unsaturated bond.) A cured product of the resin composition described in any one of claims 1 to 3. A method for producing a cured product, comprising the steps of forming a layer of the resin composition described in any one of claims 1 to 3 on a substrate, and curing the layer of the resin composition. An electronic component comprising a cured product of the resin composition described in any one of claims 1 to 3.