WO2020203648A1

WO2020203648A1 - Photosensitive resin composition for planarization film formation, method for producing electronic device, and electronic device

Info

Publication number: WO2020203648A1
Application number: PCT/JP2020/013667
Authority: WO
Inventors: 律也川崎; 美樹高坂
Original assignee: 住友ベークライト株式会社
Priority date: 2019-04-01
Filing date: 2020-03-26
Publication date: 2020-10-08
Also published as: JPWO2020203648A1; JP2021152679A; TW202112956A

Abstract

A photosensitive resin composition for planarization film formation, which contains an epoxy resin, a phenoxy resin and a sensitizing agent, wherein the amount of phenoxy resin relative to 100 parts by mass of the epoxy resin is 20-60 parts by mass. This photosensitive resin composition preferably contains a surfactant, an adhesion assistant and the like. It is preferable that this photosensitive resin composition has a viscosity of 1-50,000 mPa∙s at 25°C. It is preferable that the phenoxy resin has a weight average molecular weight of from 10,000 to 100,000. It is preferable that the epoxy resin contains a polyfunctional epoxy resin that contains three of more epoxy groups in each molecule.

Description

Photosensitive resin composition for forming a flattening film, manufacturing method of electronic device and electronic device

The present invention relates to a photosensitive resin composition for forming a flattening film, a method for manufacturing an electronic device, and an electronic device.

In the manufacture of electronic devices, it may be required to form a flat resin film with a photosensitive resin composition. For example, it may be required to form a flat resin film on a substrate having a step such as Cu wiring.

Patent Document 1 describes that a photosensitive insulating film is produced by a plurality of layers of an organic-inorganic photosensitive resin layer having a siloxane structure and an organic resin layer. According to Patent Document 1, the heat shrinkage of such a photosensitive insulating film is small, and thus good flatness can be ensured.
Further, in Patent Document 1, even if a conventional photosensitive resin composition is used alone to form a flat film on a substrate having a step, the film shrinks due to thermosetting to obtain a flat film. It is stated that it is difficult. (For example, see FIG. 1 of Patent Document 1. It is described that the film "shrinks by about 40%" due to thermosetting, and the flatness of the film is impaired.)

Patent Document 2 describes a negative photosensitive resin composition containing a polyfunctional epoxy resin, a photopolymerization initiator, a coupling agent containing an acid anhydride as a functional group, and a thermoplastic resin such as a phenoxy resin. Are listed. Further, Patent Document 2 describes that the amount of a thermoplastic resin such as a phenoxy resin added is 10 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the polyfunctional epoxy resin.
Patent Document 2 describes that a flattened photosensitive resin layer can be formed (for example, paragraphs 0072 and 0076).

Japanese Patent Application Laid-Open No. 2007-086476 International Publication No. 2019/044817

In Patent Document 1, a plurality of types of resin compositions are used in order to obtain a flat resin film on a substrate having a step. That is, in Patent Document 1, the surface of the resin film is flattened by forming a plurality of layers of the resin film by using a plurality of resin compositions.
However, using a plurality of resin compositions to obtain a flat resin film leads to complication of the process and cost increase.
It is desired that a flat resin film can be obtained without using a plurality of resin compositions in combination.

In Examples 9 to 11 of Patent Document 2, specifically, a photosensitive resin composition containing 17.7 parts by mass of a phenoxy resin with respect to 100 parts by mass of a polyfunctional epoxy resin is prepared.
A step of forming through wiring or the like may be added by forming a through hole in the resin film made of the photosensitive resin composition and then forming a conductive portion in the through hole. In forming the conductive portion, a method of depositing a seed layer on the inner surface of the through hole and then depositing a metal on the seed layer by an electrolytic plating method is used. In this method, it is necessary to deposit the seed layer on the inner surface of the through hole as closely as possible. Therefore, when processing the resin film, it is required to process the seed layer into a shape that is easy to deposit.

However, the resin film made of the photosensitive resin compositions of these examples of Patent Document 2 may have a shape in which the side surface of the through hole is inclined inward as it is closer to the opening of the through hole (reverse taper shape). It was. With this reverse taper shape, it becomes difficult for the seed layer to be deposited on the side surface of the through hole, and poor deposition of the seed layer occurs. Such poor vapor deposition also affects the precipitation of metal by the electrolytic plating method, and may cause an increase in the defective rate in the formation of the conductive portion to be filled in the through hole.

Therefore, the present inventor can form a flat resin film by itself without using it in combination with other resin compositions, and can form a through hole having a vertical side surface or a forward taper shape. For the purpose of providing a photosensitive resin composition for forming the resin film flattening film that can be provided, studies were conducted from various viewpoints.

As a result of diligent studies, the present inventor has completed the invention provided below.

According to the present invention
A photosensitive resin composition for forming a flattening film, which comprises an epoxy resin, a phenoxy resin, and a photosensitizer, and the amount of the phenoxy resin is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin.
Is provided.

Further, according to the present invention,
A film forming step of forming a photosensitive resin film on the surface of a substrate having a step on the surface by using the above-mentioned photosensitive resin composition, and
The exposure step of exposing the photosensitive resin film and
A developing process for developing the exposed photosensitive resin film and
Manufacturing method of electronic devices including
Is provided.

Further, according to the present invention,
An electronic device including a film formed of the above-mentioned photosensitive resin composition is provided.

According to the present invention, it is possible to form a flat resin film by itself without using it in combination with other resin compositions, and a resin capable of forming through holes having vertical or forward tapered side surfaces. A photosensitive resin composition for forming a flattening film, which can provide a film, is provided.

It is a figure which shows an example of the manufacturing method of an electronic device schematically. It is a figure for demonstrating the evaluation method of an Example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate.
In order to avoid complication, when there are a plurality of the same components in the same drawing, only one of them may be coded and all of them may not be coded.
All drawings are for illustration purposes only. The shape and dimensional ratio of each member in the drawing do not necessarily correspond to the actual article.

In the present specification, the notation of "a to b" in the description of the numerical range indicates a or more and b or less unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass or more and 5% by mass or less".

In the notation of a group (atomic group) in the present specification, the notation that does not indicate whether it is substituted or unsubstituted includes both those having no substituent and those having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
The notation "(meth) acrylic" herein represents a concept that includes both acrylic and methacrylic. The same applies to similar notations such as "(meth) acrylate".
The term "electronic device" as used herein refers to an element to which electronic engineering technology is applied, such as a semiconductor chip, a semiconductor element, a printed wiring board, an electric circuit display device, an information communication terminal, a light emitting diode, a physical battery, and a chemical battery. , Devices, final products, etc.

<Photosensitive resin composition>
The photosensitive resin composition of the present embodiment is used, for example, in the production of an electronic device, for forming a flattening film or for forming a through hole.
Specifically, "flattening" means applying a photosensitive resin composition on a substrate having irregularities to cover the irregularities, and flattening the outermost surface of the substrate with a photosensitive resin film.
The photosensitive resin composition of the present embodiment contains an epoxy resin, a phenoxy resin, and a photosensitive agent.

Regarding the mechanism capable of forming a flat resin film by itself of the photosensitive resin composition of the present embodiment without combining with other resin compositions, the volume change of the film when the photosensitive resin film is thermally cured ( It is presumed that the contraction) is small.
When a film is formed of the photosensitive resin composition described in Patent Document 1, it is considered that the film tends to shrink significantly because a ring closure reaction accompanied by elimination of water molecules occurs during curing. On the other hand, in the photosensitive resin composition of the present embodiment, the film is cured by the cationic polymerization reaction of the epoxy group, but this reaction basically does not cause elimination of water molecules and the like. From this, it is estimated that the volume change can be suppressed.
In addition, the photosensitive resin composition of the present embodiment contains a phenoxy resin, that is, a polyhydroxypolyether synthesized from bisphenols and epichlorohydrin. Epoxy equivalents of phenoxy resins are usually much higher than the epoxy equivalents of epoxy resins (ie, the epoxy group content is much lower or they have no epoxy groups). It is presumed that this suppresses excessive thermosetting and makes the volume change (shrinkage) of the film sufficiently small. Further, since the phenoxy resin is generally thermoplastic, it is considered that the phenoxy resin flows appropriately when heated. It is also estimated that this flow makes the film surface flatter.

The components and properties of the photosensitive resin composition of this embodiment will be described.

(Epoxy resin)
The photosensitive resin composition of the present embodiment contains an epoxy resin.
As the epoxy resin, for example, an epoxy resin having two or more epoxy groups in one molecule can be used. As the epoxy resin, monomers, oligomers, and polymers in general can be used. The molecular weight and molecular structure of the epoxy resin are not particularly limited.

Examples of the epoxy resin include phenol novolac type epoxy resin, cresol novolac type epoxy resin, cresol naphthol type epoxy resin, biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, phenoxy resin, naphthalene skeleton type epoxy resin, and bisphenol A type epoxy resin. , Bisphenol A diglycidyl ether type epoxy resin, bisphenol F type epoxy resin, bisphenol F diglycidyl ether type epoxy resin, bisphenol S diglycidyl ether type epoxy resin, glycidyl ether type epoxy resin, cresol novolac type epoxy resin, aromatic polyfunctional Examples thereof include epoxy resins, aliphatic epoxy resins, aliphatic polyfunctional epoxy resins, alicyclic epoxy resins, and polyfunctional alicyclic epoxy resins.
The epoxy resin may be used alone or in combination of two or more.

The epoxy resin can include a solid epoxy resin having two or more epoxy groups in the molecule. As the solid epoxy resin, a resin having two or more epoxy groups and solid at 25 ° C. (room temperature) can be used. Thereby, the mechanical properties of the photosensitive resin composition in the resin film can be enhanced.

The epoxy resin preferably contains a trifunctional or higher functional epoxy resin in the molecule (that is, a polyfunctional epoxy resin having three or more epoxy groups in one molecule). As a result, the film is sufficiently cured, and for example, the heat resistance and durability of the permanent film can be improved. Further, the high heat resistance means that the properties of the permanent film are unlikely to change even by heating, which leads to further improvement of flatness.

Examples of the trifunctional or higher functional epoxy resin include phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, bisphenol A type epoxy resin, and tetramethylbisphenol F. It is preferable to contain one or more kinds of epoxy resins selected from the group consisting of type epoxy resins, and it is more preferable to contain a triphenylmethane type epoxy resin or a novolak type epoxy resin. As a result, an appropriate coefficient of thermal expansion can be realized while increasing the heat resistance of the resin film.

The epoxy resin may contain a liquid epoxy resin having two or more epoxy groups in the molecule. The liquid epoxy resin functions as a filming agent and can improve the brittleness of the resin film of the photosensitive resin composition.

As the liquid epoxy resin, an epoxy compound having two or more epoxy groups and being liquid at room temperature of 25 ° C. can be used. The viscosity of the liquid epoxy resin at 25 ° C. is, for example, 1 to 8000 mPa · s, preferably 5 to 1500 mPa · s, and more preferably 10 to 1400 mPa · s.

The liquid epoxy resin can include, for example, one or more selected from the group consisting of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, alkyl diglycidyl ether and alicyclic epoxy. These may be used alone or in combination of two or more. Among these, alkyl diglycidyl ether can be used from the viewpoint of reducing cracks after development.

The epoxy equivalent of the liquid epoxy resin is, for example, 100 to 200 g / eq, preferably 105 to 180 g / eq, and more preferably 110 to 170 g / eq. Thereby, the brittleness of the resin film can be improved.

The lower limit of the content of the liquid epoxy resin is, for example, 5% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more with respect to the entire non-volatile component of the photosensitive resin composition. Thereby, the brittleness of the finally obtained cured film can be improved.
The upper limit of the content of the liquid epoxy resin is, for example, 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less with respect to the entire non-volatile component of the photosensitive resin composition. Thereby, the film characteristics of the cured film can be balanced.

The lower limit of the content of the epoxy resin is, for example, 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more with respect to the entire non-volatile component of the photosensitive resin composition. As a result, the heat resistance and mechanical strength of the finally obtained cured film can be improved.
The upper limit of the content of the epoxy resin is, for example, 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less, based on the entire non-volatile component of the photosensitive resin composition. Thereby, the patterning property can be improved.
Here, the non-volatile component of the photosensitive resin composition means the balance excluding the volatile components such as water and solvent. The content of the photosensitive resin composition with respect to the entire non-volatile component refers to the content of the photosensitive resin composition with respect to the entire non-volatile component excluding the solvent when the solvent is contained.

The weight average molecular weight (Mw) of the epoxy resin is not particularly limited. Mw is, for example, 300 to 9000, preferably 500 to 8000. By using an epoxy resin having a relatively low molecular weight, the reactivity at the time of exposure can be enhanced.

The photosensitive resin composition of the present embodiment may contain a thermosetting resin other than the epoxy resin. Examples of other thermosetting resins include resins having a triazine ring such as urea resin and melamine resin; unsaturated polyester resin; maleimide resin such as bismaleimide compound; polyurethane resin; diallyl phthalate resin; silicone resin. Examples thereof include benzoxazine resin; polyimide resin; polyamideimide resin; benzocyclobutene resin, novolak type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, and tetramethylbisphenol F type cyanate resin.
When other thermosetting resins are used, they may be used alone or in combination of two or more.

(Phenoxy resin)
The photosensitive resin composition of the present embodiment contains a phenoxy resin. It is considered that the phenoxy resin also has a function of increasing the flexibility of the film.

Examples of the phenoxy resin include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol A type and bisphenol F type copolymerized phenoxy resin, biphenyl type phenoxy resin, bisphenol S type phenoxy resin, biphenyl type phenoxy resin and bisphenol. Examples thereof include a phenoxy resin copolymerized with an S-type phenoxy resin. Of these, a bisphenol A type phenoxy resin or a copolymerized phenoxy resin of a bisphenol A type and a bisphenol F type is preferable.
The phenoxy resin may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the phenoxy resin is preferably 10,000 to 100,000, more preferably 20,000 to 80,000, and even more preferably 35,000 to 80,000.
Since the Mw of the phenoxy resin is relatively large, the curing shrinkage can be further suppressed, and the flatness can be further improved. The details of this mechanism are unknown, but it is speculated that when Mw is relatively large, the thermal motion of the molecular chain is suppressed, and as a result, the flatness is further improved.
On the other hand, the Mw of the phenoxy resin is preferably 100,000 or less in terms of solvent solubility and the like.
The weight average molecular weight is measured, for example, as a polystyrene-equivalent value by gel permeation chromatography (GPC).

The phenoxy resin may have a reactive group such as an epoxy group at both ends of the molecular chain or inside the molecular chain. The reactive group in the phenoxy resin is one capable of cross-linking with the epoxy group in the epoxy resin. By using such a phenoxy resin, the solvent resistance and heat resistance in the resin film can be enhanced.

As the phenoxy resin, one that is solid at 25 ° C. is preferably used. Specifically, a phenoxy resin having a non-volatile content of 90% by mass or more is preferably used. By using such a phenoxy resin, the mechanical properties of the cured product can be improved.

The lower limit of the content of the phenoxy resin is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 28 parts by mass or more with respect to 100 parts by mass of the epoxy resin. Thereby, a through hole having a vertical shape or a forward taper shape on the side surface can be formed, and further sufficient flexibility can be obtained. In addition, it is considered that the effect of flattening the film surface by suppressing excessive thermosetting and flowing as described above as an estimation mechanism can be sufficiently obtained.

The upper limit of the content of the phenoxy resin is preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and further preferably 50 parts by mass or less with respect to 100 parts by mass of the epoxy resin. As a result, the crosslink density is optimized, a resin film having excellent film physical properties such as glass transition point and elongation can be provided, and the phenoxy resin is sufficiently dissolved in a solvent described later, resulting in excellent coatability. A photosensitive resin composition can be obtained.
Further, when the content of the phenoxy resin exceeds the upper limit value, the required exposure amount increases. Therefore, when the required exposure amount exceeds the assumption, the via width in which the reaction of the composition does not proceed sufficiently. May become too wide. Therefore, if it is not more than the upper limit value, a desired through hole can be formed without applying an increase in the amount of exposure that leads to an increase in the exposure process time.

The photosensitive resin composition of the present embodiment may contain a thermoplastic resin other than the phenoxy resin. Examples of the thermoplastic resin include polyvinyl acetal resin, (meth) acrylic resin, polyamide resin (for example, nylon), thermoplastic urethane resin, polyolefin resin (for example, polyethylene, polypropylene, etc.), polycarbonate, and polyester resin (for example, polyethylene). For example, polyethylene terephthalate, polybutylene terephthalate, etc.), polyacetal, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin (for example, polytetrafluoroethylene, polyvinylidene fluoride, etc.), modified polyphenylene ether, polysulfone, polyether sulfone, poly Examples thereof include allylate, polyamideimide, polyetherimide, and thermoplastic polyimide.
When other thermoplastic resins are used, they may be used alone or in combination of two or more.

(Photosensitive agent)
The photosensitive resin composition of the present embodiment contains a photosensitive agent. As a result, the patterning performance of the photosensitive resin composition such as sensitivity and resolution can be improved.
The photosensitizer typically comprises a photoacid generator, i.e. a compound that generates an acid upon irradiation with light such as g-ray or i-ray.
The photosensitive resin composition of the present embodiment is usually a chemically amplified photosensitive resin composition in which an acid generated from a photoacid generator acts catalytically (the acid generated from the photoacid generator is an epoxy group). The polymerization is initiated and the acid is catalytically regenerated).
The photosensitive resin composition of the present embodiment is usually a negative type. That is, at the time of development, the exposed portion usually remains and the unexposed portion is removed.

Examples of the photosensitizer include onium salt compounds. More specifically, iodonium salts such as diazonium salt and diaryliodonium salt, sulfonium salts such as triarylsulfonium salt, triarylvirylium salt, benzylpyridinium thiocyanate, dialkylphenacil sulfonium salt, dialkylhydroxyphenylphosphonium salt and the like. , Photoacid generator or cationic photopolymerization initiator.
Above all, from the viewpoint of patterning property, it is preferable to use a triarylsulfonium salt.

Examples of the counter anion of the onium salt compound include borate anion, sulfonate anion, gallate anion, phosphorus anion, antimony anion and the like. More specifically, sulfonic acid anion, disulfonylimide acid anion, hexafluorophosphate anion, fluoroantimonate anion, tetrafluoroborate anion, tetrakis (pentafluorophenyl) borate anion and the like can be mentioned.

The photosensitizer may be used alone or in combination of two or more.
The content of the photosensitizer is, for example, 0.3 to 5.0% by mass, preferably 0.5 to 4.5% by mass, and more preferably 1.0, based on the total solid content of the photosensitive resin composition. It is about 4.0% by mass. By setting the content to 0.3% by mass or more, the patterning property can be improved. Further, by setting the content to 5.0% by mass or less, the ionic component in the membrane can be reduced, and the insulating property and reliability of the final membrane can be improved.

(Surfactant)
The photosensitive resin composition of the present embodiment preferably contains a surfactant. By including the surfactant, the coatability is improved, and a more uniform / flat resin film and a cured film can be obtained.
Examples of the surfactant include a fluorine-based surfactant, a silicone-based surfactant, an alkyl-based surfactant, an acrylic-based surfactant, and the like.

The surfactant preferably contains a surfactant containing at least one of a fluorine atom and a silicon atom. More preferably, the surfactant is, for example, a nonionic surfactant containing at least one of a fluorine atom and a silicon atom.
Commercially available products that can be used as surfactants include, for example, F-251, F-253, F-281, F-430, F-477, F-551, of the "Mega Fvck" series manufactured by DIC Co., Ltd. F-552, F-553, F-554, F-555, F-556, F-557, F-558, F-559, F-560, F-561, F-562, F-563, F- 565, F-568, F-569, F-570, F-572, F-574, F-575, F-576, R-40, R-40-LM, R-41, R-94, etc. Fluorine-containing oligomeric surfactants, Fluorine-containing nonionic surfactants such as Futtergent 250 and Futtergent 251 manufactured by Neos Co., Ltd., SILFOAM® series manufactured by Wacker Chemie (eg SD 100 TS) , SD 670, SD 850, SD 860, SD 882) and other silicone-based surfactants.
In the present embodiment, from the viewpoint of the effect of the present invention, the surfactant preferably contains a fluorine-based surfactant.

When a surfactant is used, it may be used alone or in combination of two or more.
When a surfactant is used, the amount thereof shall be, for example, 0.001 to 1% by mass, preferably 0.005 to 0.5% by mass, based on the total amount of the non-volatile components of the photosensitive resin composition. Can be done.

(Adhesion aid)
The photosensitive resin composition of the present embodiment preferably contains an adhesion aid. Thereby, for example, the adhesion to the substrate can be further improved.

The adhesion aid is not particularly limited. For example, amino group-containing silane coupling agent, epoxy group-containing silane coupling agent, (meth) acryloyl group-containing silane coupling agent, mercapto group-containing silane coupling agent, vinyl group-containing silane coupling agent, ureido group-containing silane cup. A silane coupling agent such as a ring agent or a sulfide group-containing silane coupling agent can be used.
When a silane coupling agent is used, one type may be used alone, or two or more types may be used in combination.

Examples of the amino group-containing silane coupling agent include bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropylmethyldiethoxy. Silane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-amino Examples thereof include propylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane, and N-phenyl-γ-amino-propyltrimethoxysilane.
Examples of the epoxy group-containing silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidyl. Examples thereof include propyltrimethoxysilane.
Examples of the (meth) acryloyl group-containing silane coupling agent include γ-((meth) acryloyloxypropyl) trimethoxysilane, γ-((meth) acryloyloxypropyl) methyldimethoxysilane, and γ-((meth)). Acryloyloxypropyl) methyldiethoxysilane and the like.
Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropyltrimethoxysilane.
Examples of the vinyl group-containing silane coupling agent include vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane and the like.
Examples of the ureido group-containing silane coupling agent include 3-ureidopropyltriethoxysilane and the like.
Examples of the sulfide group-containing silane coupling agent include bis (3- (triethoxysilyl) propyl) disulfide and bis (3- (triethoxysilyl) propyl) tetrasulfide.
Examples of the acid anhydride-containing silane coupling agent include 3-trimethoxysilylpropyl succinic anhydride, 3-triethoxycyclylpropyl succinic anhydride, 3-dimethylmethoxysilylpropyl succinic anhydride and the like.

Further, as the adhesion aid, not only a silane coupling agent but also a titanium coupling agent, a zirconium coupling agent and the like can be mentioned.

When the adhesion aid is used, it may be used alone or in combination of two or more kinds of adhesion aids.
When the adhesion aid is used, the amount used is preferably 0.3 to 5% by mass, more preferably 0.4 to 4% by mass, still more preferably, based on the total amount of the non-volatile components of the photosensitive resin composition. Is 0.5 to 3% by mass.

(Additive)
The photosensitive resin composition of the present embodiment may contain other additives in addition to the above components, if necessary. Examples of other additives include antioxidants, fillers such as silica, sensitizers, filming agents and the like.

(solvent)
The photosensitive resin composition of the present embodiment preferably contains a solvent. As a result, a photosensitive resin film can be easily formed on the stepped substrate by the coating method.
The solvent usually includes an organic solvent. The organic solvent is not particularly limited as long as each of the above-mentioned components can be dissolved or dispersed and does not substantially chemically react with each of the components.

Examples of the organic solvent include acetone, methyl ethyl ketone, toluene, propylene glycol methyl ethyl ether, propylene glycol dimethyl ether, propylene glycol 1-monomethyl ether 2-acetate, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and benzyl. Examples thereof include alcohol, propylene carbonate, ethylene glycol diacetate, propylene glycol diacetate, propylene glycol monomethyl ether acetate, diproprene glycol methyl-n-propyl ether, butyl acetate and γ-butyrolactone. These may be used alone or in combination of two or more.

The solvent is used so that the concentration of the total amount of the non-volatile components in the photosensitive resin composition is preferably 30 to 75% by mass, more preferably 35 to 70% by mass. Within this range, each component can be sufficiently dissolved or dispersed. In addition, good coatability can be ensured, which in turn leads to further improvement in flatness. Further, by adjusting the content of the non-volatile component, the viscosity of the photosensitive resin composition can be appropriately controlled.

(viscosity)
The viscosity of the photosensitive resin composition at 25 ° C. is preferably 1 to 50,000 mPa · s, more preferably 10 to 10,000 mPa · s, still more preferably 50 to 5,000 mPa · s. By setting the viscosity within the above numerical range, the thickness of the coating film can be appropriately controlled. In addition, it is easy to improve the flatness of the film.
The viscosity can be measured, for example, using a cone plate type viscometer (TV-25, manufactured by Toki Sangyo). The rotation speed at the time of measurement can be set to 100 rpm as an example, and can be set to 20 rpm when an appropriate viscosity measurement cannot be performed at 100 rpm.
The coating thickness is appropriately adjusted in the range of, for example, 1 to 100 μm, preferably 3 to 80 μm, and more preferably 5 to 50 μm.

<Manufacturing method of electronic devices, electronic devices>
Using the photosensitive resin composition of the present embodiment, an electronic device (an electronic device including a film formed of the photosensitive resin composition) can be manufactured. Examples of electronic devices include display devices such as liquid crystal displays, organic EL displays, touch panels, electronic paper, color filters, mini LED displays, and micro LED displays, solar cells, light receiving devices such as CMOS, and the like. It can be used as an interlayer insulating film, a sealing material (top coat), and the like.
In the present embodiment, a method of manufacturing an electronic device including a rewiring layer made of a photosensitive resin film will be described.
For example, (i) a film forming step of forming a photosensitive resin film using the photosensitive resin composition of the present embodiment on the surface of a substrate having a step on the surface, and (ii) exposing the photosensitive resin film. An electronic device can be manufactured by a method for manufacturing an electronic device, which includes an exposure step and (iii) a development step of developing an exposed photosensitive resin film.

The manufacturing method of the electronic device will be described more specifically with reference to FIGS. 1A to 1D.

(Film formation process: Fig. 1A)
In the film forming step, the photosensitive resin film 3 is formed on the surface side of the substrate 1 having the step 10 by using the photosensitive resin composition of the present embodiment. The surface having a step is flattened by the photosensitive resin film 3.
The substrate 1 is not particularly limited. Examples of the substrate 1 include a silicon wafer, a ceramic substrate, an aluminum substrate, a SiC wafer, and a GaN wafer.
The step 10 is, for example, Cu rewiring. Of course, the step 10 may be a step other than Cu rewiring. The height of the step 10 is, for example, 1 to 10 μm, preferably 1 to 5 μm.
The thickness of the photosensitive resin film 3 (thickness of the portion without the step 10) is, for example, 1 to 15 μm, preferably 1 to 10 μm. This thickness may be larger than the height of the step 10.

As a method for forming the photosensitive resin film 3, a method of applying a liquid photosensitive resin composition on a substrate by a spin coating method, a spray coating method, a dipping method, a printing method, a roll coating method, an inkjet method, or the like is used. Can be mentioned. The method of forming the resin film is typically spin coating.
The thickness of the photosensitive resin film 3 can be adjusted by changing the film forming conditions or adjusting the viscosity of the photosensitive resin composition.

It is preferable to heat-dry the photosensitive resin film 3 after the film-forming step and before the exposure step. This heat drying is sometimes called "pre-baking".
The heat-drying temperature is usually 50 to 180 ° C, preferably 60 to 150 ° C. The heating and drying time is usually about 30 to 600 seconds, preferably about 30 to 300 seconds. The solvent in the photosensitive resin composition can be sufficiently removed by this heat drying. Heating is typically performed on a hot plate, oven, or the like.

(Exposure process: FIG. 1B)
In the exposure step, the photosensitive resin film 3 is exposed through the photomask 20. Examples of the active light beam for exposure include X-ray, electron beam, ultraviolet light, visible light and the like. In terms of wavelength, active light rays having a wavelength of 200 to 500 nm are preferable. From the viewpoint of pattern resolution and ease of handling of the device, the light source is preferably g-line, h-line or i-line of a mercury lamp. Further, two or more light rays may be mixed and used.
As the exposure apparatus, a contact aligner, a mirror projection or a stepper is preferable.
Exposure dose in the exposure step is usually 40 ~ 1500mJ / cm ^2, preferably between 80 ~ 1000mJ / cm ^2, the sensitivity of the photosensitive resin composition, the film thickness of the resin film, due to the shape of the pattern to be obtained It will be adjusted accordingly.

It is preferable to heat the resin film (heat after exposure) between the exposure step and the developing step. As a result, the reaction of substances (photosensitive agents, etc.) that have been cleaved or decomposed by exposure proceeds, and improvement in pattern shape can be expected. The temperature and time of heating after exposure is, for example, about 50 to 200 ° C. and 10 to 600 seconds.

(Development process: Fig. 1C)
In the developing step, the developing solution is used to develop the photosensitive resin film exposed in the exposure step. As a result, a part of the photosensitive resin film 3 can be removed to obtain a resin film 3A having an opening 5. The photosensitive resin composition of the present embodiment is usually a negative type. Therefore, the opening 5 is provided in the portion of the photomask 20 corresponding to the light-shielding portion.
Since the resin film made of the photosensitive resin composition of the present embodiment can form a through hole (opening 5) having a vertical shape or a forward taper shape on the side surface, the yield is increased in the formation of the conductive portion filled in the through hole. improves.
The developing step can be performed by, for example, a dipping method, a paddle method, a rotary spray method, or the like.

In the present embodiment, the developer preferably contains an organic solvent. More specifically, the developing solution is preferably a developing solution containing an organic solvent as a main component (a developing solution in which 95% by mass or more of the components are organic solvents). By developing with a developing solution containing an organic solvent, it is possible to suppress swelling of the pattern due to the developing solution as compared with the case of developing with an alkaline developing solution (aqueous system). That is, it is easy to obtain a finer pattern.

Specific examples of the organic solvent that can be used in the developing solution include ketone solvents such as cyclopentanone, ester solvents such as propylene glycol monomethyl ether acetate (PGMEA) and butyl acetate, and ether solvents such as propylene glycol monomethyl ether. And so on.
As the developing solution, an organic solvent developing solution containing only an organic solvent and containing only impurities inevitably contained may be used. The impurities that are unavoidably contained include metal elements, but from the viewpoint of preventing contamination of electronic devices, the impurities that are unavoidably contained are small.

The time of the developing step is usually about 5 to 300 seconds, preferably about 10 to 120 seconds, and is appropriately adjusted based on the film thickness of the resin film and the shape of the formed pattern.

For example, there may be a curing step of curing the resin film 3A between the developing step and the subsequent steps. Curing can be performed, for example, by heat treatment at 150 to 250 ° C. for 30 to 240 minutes. By forming the resin film 3A using the photosensitive resin composition of the present embodiment, the flatness of the surface (upper surface) of the resin film 3A is good even after undergoing such a curing step.

(Additional rewiring process: Fig. 1D)
A Cu rewiring 11 different from the step 10 (for example, Cu rewiring) can be provided in the portion of the opening 5 provided in the developing step. At this time, since the side surface of the opening 5 has a vertical shape or a forward taper shape, the seed layer is easily deposited on the side surface in the opening 5, the metal filling by the electroplating method is improved, and the yield of the Cu rewiring 11 is increased. improves. Further, since the upper surface of the resin film 3A is highly flat, the fine Cu rewiring 11 can be provided with high accuracy.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

An embodiment of the present invention will be described in detail based on Examples and Comparative Examples. The present invention is not limited to the examples.

<Preparation of photosensitive resin composition>
-Examples 1 to 5, Comparative Examples 2 to 3
Each component listed in Table 1 was dissolved in propylene glycol monomethyl ether acetate (PGMEA) to prepare a solution. The solution was then filtered through a 0.2 μm polypropylene filter. As a result, a photosensitive resin composition having a viscosity of about 100 mPa · s was obtained at 25 ° C. (the amount of PGMEA was appropriately adjusted so that the viscosity was about 100 mPa · s).
The viscosity of the photosensitive resin composition was measured using a cone plate type viscometer (TV-25, manufactured by Toki Sangyo) with the rotation speed set to 100 rpm.
Comparative Example 2 is the photosensitive resin composition described in Example 10 of International Publication No. 2019/044817.

・ Comparative example 1
The photosensitive resin composition (containing a polybenzoxazole precursor) described in Example 1 of JP-A-11-237736 was prepared.

The details of the raw materials of each component in Table 1 are as follows.
(Epoxy resin)
Epoxy resin 1: Polyfunctional epoxy resin represented by the following structure ("EPPN201" manufactured by Nippon Kayaku Co., Ltd., phenol novolac type epoxy resin, solid at 25 ° C., n is about 5)

Epoxy resin 2: Polyfunctional epoxy resin (Mitsubishi Chemical Corporation "jER1032H60", triphenylmethane type epoxy resin, solid at 25 ° C)
Epoxy resin 3: Cresol novolac type epoxy resin (Nippon Kayaku Co., Ltd. "EOCN-1020", solid at 25 ° C)

(Phenoxy resin)
Phenoxy resin 1: Bisphenol A type phenoxy resin ("jER1256" manufactured by Mitsubishi Chemical Corporation, Mw: about 50,000))
Phenoxy resin 2: Bisphenol A type phenoxy resin (manufactured by PKHA Gabriel Phoenixies, Mw: about 25,000))
Phenoxy resin 3: Bisphenol A type / Bisphenol F type phenoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd. "YP-70")

(Photosensitizer (photoacid generator))
Photoacid generator 1: Triarylsulfonium borate salt (manufactured by San-Apro, CPI-310B)

(Surfactant)
Surfactant 1: Fluorine-containing group / lipophilic group-containing oligomer (manufactured by DIC Corporation, R-41)
Surfactant 2: Polyacrylate-based surface conditioner (manufactured by Big Chemie Japan, BYK-365N)

(Adhesion aid)
Adhesion aid 1: 3-glycidoxypropyltrimethoxysilane (silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403)
Adhesion aid 2: 3-trimethoxysilylpropyl succinic anhydride (silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd., X-12-967C)

<Evaluation of flatness>
Using the photosensitive resin compositions of Examples 1 to 5 and Comparative Examples 2 and 3, wafers with a cured film were obtained by the following procedure.
(1) As a substrate, a silicon wafer having a height of 3 to 4 μm and a width of 100 μm and having steps (convex portions) formed by Cu provided at a pitch of 200 μm was prepared.
(2) The photosensitive resin composition was applied to the stepped surface of the substrate by spin coating, and then dried in the air at 100 ° C. for 6 minutes. As a result, a photosensitive resin film was formed on the substrate.
(3) The photosensitive resin film formed in (2) above is 800 mJ / using a manual exposure machine (mixed light of HMW-201GX, g-line, i-line, h-line, etc. manufactured by ORC Manufacturing Co., Ltd.). The entire surface was exposed with an exposure amount of cm ² .
(4) After the exposure of (3) above, the photosensitive resin film was cured by heat treatment at 170 ° C. for 120 minutes in a nitrogen atmosphere.

Further, using the photosensitive resin composition of Comparative Example 1, the condition of (2) above was set to 120 ° C. for 4 minutes, the exposure of (3) above was omitted, and tetramethyl between (3) and (4) above was omitted. Development with a 2.38 mass% aqueous solution of ammonium hydroxide (TMAH) and rinsing with pure water were carried out, except that the condition (4) above was changed to 30 minutes at 150 ° C. and then 30 minutes at 320 ° C. Wafers with a cured film were obtained under the same conditions as in Examples 1 to 5.

The wafer with the cured film obtained above was split, and the cross section thereof was enlarged and photographed.
Based on the captured image, _HA (the sum of the thickness of the cured film on the convex step and the height of the convex step) and H _B (the part without the convex step) shown in FIG. The thickness of the cured film) and _HS (height of the convex step) were determined.
The absolute value of _{_{_{_{H A -H B | H A -H}}}} B | ( unit: [mu] m), _{_{and, {| H A -H B |}} / H S} × 100 ( unit:%) by the evaluation formula, the flatness evaluated. The smaller the value of these evaluation formulas, the better the flatness.
(Different substrate for each example, since H _S are not completely the same, in addition to the former evaluation formula was evaluated using also the latter evaluation formula representing a "cured film surface flatness per a step height" .)

<Evaluation of patterning characteristics>
Whether or not the photosensitive resin compositions of Examples 1 to 5 and Comparative Examples 2 to 3 can be patterned into a desired shape by exposure and development (patternability), and the via pattern shape to be formed are as follows. The patterning characteristics were evaluated according to the following criteria.

The photosensitive resin compositions of Examples 1 to 5 and Comparative Examples 2 to 3 were applied onto an 8-inch silicon wafer using a spin coater. After coating, it was prebaked on a hot plate in the air at 100 ° C. for 6 minutes to obtain a coating film having a film thickness of about 9.0 μm. The coating film was irradiated with i-line at 600 mJ / cm ² through a mask on which a via pattern having a width of 100 μm was drawn. An i-line stepper (NSR-4425i manufactured by Nikon Corporation) was used for irradiation. After the exposure, the wafer was placed on a hot plate and baked in the air at 70 ° C. for 5 minutes. Then, PGMEA was used as a developing solution, and spray development was carried out for 30 seconds to dissolve and remove the unexposed portion to obtain a via pattern.
The cross section of the obtained via pattern was observed using a tabletop SEM. The width at the height between the bottom surface of the via pattern and the opening was defined as the via width.
Based on the patternability and via pattern shape, the patterning characteristics were evaluated according to the following criteria (criteria).
◯: The via width is 95 to 105 μm, and the patterning property is good. The taper angle is 90 degrees or less and is a forward taper shape or a forward taper shape.
Δ: The via width is 95 to 105 μm, and the patterning property is good. It has a reverse taper shape with a taper angle of more than 90 degrees.
X: The via width is less than 95 μm or more than 105 μm, and the patterning property is poor.

Table 1 summarizes the composition and evaluation results of the photosensitive resin composition.

As shown in Table 1, other resin compositions can be obtained by using the photosensitive resin compositions for forming a flattening film (Examples 1 to 5) containing an epoxy resin, a phenoxy resin, and a photosensitive agent. A flat resin film could be formed on the substrate having a step without using it.
Further, there was no particular problem in the patterning characteristics of the photosensitive resin compositions of Examples 1 to 5.

Looking at the results of Examples 1 to 5 in more detail, Example 1 in which the phenoxy resin 1 (Mw: 50,000) was used rather than Example 5 (Mw: 25,000) in which the phenoxy resin 2 was used. ~ 4 showed better flatness. It can be read that the larger the Mw of the phenoxy resin, the better the flatness.
Further, from the comparison between Examples 1 and 2 to 4, it can be read that the flatness is further improved when the amount of the phenoxy resin is relatively large (20% by mass or more).

Further, the photosensitive resin composition (Examples 1 to 5) containing the phenoxy resin in the range of 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin is a photosensitive resin composition outside this range (Comparative Examples 2 and 2). Compared with 3), the patterning property and the via pattern shape were excellent, and the patterning characteristics were good. In Comparative Example 3 in which the amount of the phenoxy resin exceeded the upper limit value, the required exposure amount increased, and as a result of patterning with the same exposure amount as in Examples and the like, the reaction progress of the composition was insufficient and the via width was wide. It is thought that it became.

This application claims priority based on Japanese Application Japanese Patent Application No. 2019-069700 filed on April 1, 2019, and incorporates all of its disclosures herein.

Claims

Contains an epoxy resin, a phenoxy resin, and a photosensitizer.
A photosensitive resin composition for forming a flattening film, wherein the amount of the phenoxy resin is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin.
The photosensitive resin composition according to claim 1.
A photosensitive resin composition containing a surfactant.
The photosensitive resin composition according to claim 2.
A photosensitive resin composition in which the surfactant contains a fluorine-based surfactant.
The photosensitive resin composition according to any one of claims 1 to 3.
A photosensitive resin composition containing an adhesion aid.
The photosensitive resin composition according to any one of claims 1 to 4.
A photosensitive resin composition having a viscosity at 25 ° C. of 1 to 50,000 mPa · s.
The photosensitive resin composition according to any one of claims 1 to 5.
A photosensitive resin composition having a weight average molecular weight of the phenoxy resin of 10,000 to 100,000.
The photosensitive resin composition according to any one of claims 1 to 6.
The epoxy resin is a photosensitive resin composition containing a polyfunctional epoxy resin having three or more epoxy groups in the molecule.
The photosensitive resin composition according to any one of claims 1 to 7.
A photosensitive resin composition containing a solvent.
A film forming step of forming a photosensitive resin film on the surface of a substrate having a step on the surface using the photosensitive resin composition according to any one of claims 1 to 8.
The exposure step of exposing the photosensitive resin film and
A method for manufacturing an electronic device, which comprises a developing step of developing the exposed photosensitive resin film.
An electronic device comprising a film formed of the photosensitive resin composition according to any one of claims 1 to 8.