Photocurable resin composition

Abstract

The purpose of the present invention is to provide a photocurable resin composition capable of being inhibited from oozing out when bonding wafers together, and of providing improved adhesiveness with respect to wafers by having a cured product thereof heated at a low temperature. The present invention pertains to a photocurable resin composition that is used by being applied on a wafer, and contains a curable resin. When the photocurable resin composition does not contain a solvent, the glass transition temperature of a cured product thereof obtained by irradiating the photocurable resin composition with light having a wavelength of 365 nm and an illuminance of 100 mW / cm2 for 30 seconds is at most 80°C. When the photocurable resin composition contains a solvent, the glass transition temperature of a cured product thereof obtained by removing the solvent from the photocurable resin composition and thereafter irradiating the photocurable resin composition with light having a wavelength of 365 nm and an illuminance of 100 mW / cm2 for 30 seconds is at most 80°C.

Description

Photocurable resin composition

[0001] The present invention relates to a photocurable resin composition.

[0002] In recent years, a technique called wafer-level CSP has been adopted as a packaging method for semiconductor components. Wafer-level CSP allows for thinner semiconductor components because it does not require internal wiring using bonding wires. Furthermore, it offers superior productivity because multiple semiconductor chips are packaged and then diced together. During the packaging process, which is performed before the dicing process, a silicon wafer and a glass wafer are bonded together using a curable resin composition (see, for example, Patent Document 1).

[0003] International Publication No. 2018 / 030140

[0004] When wafers (e.g., a silicon wafer and a glass wafer) are bonded together, if the curable resin composition seeps out or if the gap between the wafers cannot be precisely controlled, individual differences in performance of semiconductor components will occur. Therefore, there has been a demand for a curable resin composition that can exert sufficient adhesive strength without seeping out when wafers are bonded together.

[0005] An object of the present invention is to provide a photocurable resin composition that can suppress bleeding when wafers are bonded together and can improve adhesion to wafers by heating the cured product at a low temperature.

[0006] Disclosure 1 provides a photocurable resin composition that is applied to a wafer, and contains a curable resin. When the photocurable resin composition does not contain a solvent, the photocurable resin composition is exposed to a light source having a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ and the glass transition temperature of the cured product obtained by irradiating the photocurable resin composition with light of a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds is 80°C or lower. If the photocurable resin composition contains a solvent, the solvent is removed from the photocurable resin composition, and then the cured product is cured with light of a wavelength of 365 nm and an illuminance of 100 mW / cm. ２and a photocurable resin composition in which the glass transition temperature of the cured product obtained by irradiating the curable resin with light of 1000 nm for 30 seconds is 80°C or lower. Disclosure 2 is the photocurable resin composition of Disclosure 1, in which the curable resin includes a compound having a carboxy group and a polymerizable functional group. Disclosure 3 is the photocurable resin composition of Disclosure 1 or 2, in which the curable resin includes a compound having a ring-opened skeleton of caprolactone and a polymerizable functional group. Disclosure 4 is the photocurable resin composition of Disclosure 1, in which the curable resin includes a compound having a carboxy group and a polymerizable functional group, and a compound having a ring-opened skeleton of caprolactone and a polymerizable functional group, the content of the compound having the ring-opened skeleton of caprolactone and the polymerizable functional group being 0.20 parts by mass or more and 0.85 parts by mass or less per part by mass of the compound having the carboxy group and the polymerizable functional group, and the total content of the compound having the ring-opened skeleton of caprolactone and the compound having the polymerizable functional group in the entire curable resin is 80% by mass or more. Disclosure 5 is a photocurable resin composition according to Disclosure 1, 2, 3, or 4, which is used in a wafer bonding step in the manufacture of a CMOS image sensor. The present invention will be described in detail below.

[0007] The present inventors have investigated how to adjust the glass transition temperature of a photocurable resin composition (or the photocurable resin composition after solvent removal, if it contains a solvent) to a specific temperature or lower after photocuring for use in a photocurable resin composition applied to a wafer. As a result, they have found that it is possible to obtain a cured product that can suppress oozing when wafers are bonded together and that can improve adhesion to wafers by heating at low temperatures, leading to the completion of the present invention. When the photocurable resin composition of the present invention contains a solvent, oozing can be suppressed by removing the solvent before bonding the wafers to increase viscosity. Furthermore, by photocuring the photocurable resin composition after bonding wafers (e.g., a silicon wafer and a glass wafer) and then heating at a low temperature (80°C), it is possible to improve adhesion to the wafers while controlling the gap between the wafers.

[0008] The photocurable resin composition of the present invention is used by being coated on a wafer. By coating the photocurable resin composition of the present invention on a wafer, wafers (e.g., a silicon wafer and a glass wafer) can be bonded together via the photocurable resin composition of the present invention. Examples of wafers to which the photocurable resin composition of the present invention can be coated include silicon wafers and glass wafers. Furthermore, a spin coating method is preferably used as a method for coating the photocurable resin composition of the present invention on a wafer. When the photocurable resin composition of the present invention is coated on a wafer by the spin coating method, it is preferably coated at room temperature (15°C or higher and 25°C or lower) at a speed of 500 rpm or higher and 3000 rpm or lower.

[0009] When the photocurable resin composition of the present invention does not contain a solvent, the photocurable resin composition is exposed to a wavelength of 365 nm and an illuminance of 100 mW / cm ２ The glass transition temperature of the cured product obtained by irradiating the photocurable resin composition of the present invention with light of a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds is 80°C or lower. When the photocurable resin composition of the present invention contains a solvent, the solvent is removed from the photocurable resin composition, and then the cured product is cured with light of a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds. ２The glass transition temperature of the cured product obtained by irradiating the photocurable resin composition with light for 30 seconds is 80°C or lower. Since the glass transition temperature of the cured product is 80°C or lower, by photocuring the photocurable resin composition and then heating it at a low temperature (80°C), the adhesive strength to the wafer can be improved while controlling the gap between the wafers. The upper limit of the glass transition temperature of the cured product is preferably 75°C. There is no particular preferred lower limit for the glass transition temperature of the cured product, but the substantial lower limit is 30°C. When the photocurable resin composition of the present invention contains a solvent, an example of a method for removing the solvent from the photocurable resin composition includes applying the photocurable resin composition to a thickness of 100 μm on a release PET film (manufactured by Lintec Corporation, "PET5011") using a bar coater (manufactured by RD specialities, No. 37) and heating the applied coating at 80°C for 5 minutes. Furthermore, in this specification, the "glass transition temperature" refers to the temperature at which a maximum due to micro-Brownian motion appears among the maximum loss tangents (tan δ) obtained by dynamic viscoelasticity measurement. Specifically, the glass transition temperature is determined by performing dynamic viscoelasticity measurement using a dynamic viscoelasticity measuring device under the following conditions: test piece width 5 mm, thickness 0.50 mm, tensile mode, grip width 25 mm, heating rate 10°C / min, temperature range 0°C to 150°C, and frequency 1 Hz. Examples of the dynamic viscoelasticity measuring device include DVA-200 (manufactured by IT Measurement & Control Co., Ltd.).

[0010] The photocurable resin composition of the present invention contains a curable resin. The curable resin preferably contains a compound having a carboxy group and a polymerizable functional group. By containing the compound having a carboxy group and a polymerizable functional group, the photocurable resin composition of the present invention has better adhesion to wafers.

[0011] Examples of the polymerizable functional group possessed by the compound having a carboxy group and a polymerizable functional group include a (meth)acryloyl group, a (meth)acrylamide group, a vinyl group, a thiol group, and an epoxy group. Among these, a (meth)acryloyl group is preferred. In this specification, the term "(meth)acryloyl" refers to acryloyl or methacryloyl, and the term "(meth)acrylic" refers to acrylic or methacrylic.

[0012] Specific examples of the compound having a carboxy group and a polymerizable functional group include 2-(meth)acryloyloxyethyl phthalate and 2-(meth)acryloyloxyethyl hexahydrophthalate.

[0013] The preferred lower limit of the content of the compound having a carboxy group and a polymerizable functional group per 100 parts by mass of the curable resin is 20 parts by mass, and the preferred upper limit is 60 parts by mass. When the content of the compound having a carboxy group and a polymerizable functional group per 100 parts by mass of the curable resin is within this range, the resulting photocurable resin composition has better adhesion to wafers. The more preferred lower limit of the content of the compound having a carboxy group and a polymerizable functional group per 100 parts by mass of the curable resin is 30 parts by mass, and the more preferred upper limit is 50 parts by mass.

[0014] The curable resin preferably contains a compound having a ring-opened caprolactone skeleton and a polymerizable functional group. By containing the compound having a ring-opened caprolactone skeleton and a polymerizable functional group, the photocurable resin composition of the present invention has superior adhesion to wafers due to stress relaxation. Note that a compound having a carboxy group, a ring-opened caprolactone skeleton, and a polymerizable functional group is treated as a compound having a ring-opened caprolactone skeleton and a polymerizable functional group.

[0015] Examples of the polymerizable functional group contained in the compound having a ring-opened caprolactone skeleton and a polymerizable functional group include a (meth)acryloyl group, a (meth)acrylamide group, a vinyl group, a thiol group, an epoxy group, etc. Among these, a (meth)acryloyl group is preferred.

[0016] Specific examples of the compound having a ring-opened caprolactone skeleton and a polymerizable functional group include compounds represented by the following formula (1).

[0017]

[0018] In formula (1), R １ represents a hydrogen atom or a methyl group, R ２ represents a group represented by the following formula (2-1), (2-2), or (2-3), and R ３ represents a structure derived from an optionally substituted dicarboxylic acid or an anhydride thereof, X represents a ring-opened structure of caprolactone, n is 1 or more and 5 or less, and Ep represents a structure derived from a difunctional or higher functional epoxy compound.

[0019]

[0020] In formulas (2-1), (2-2), and (2-3), * and ** represent bonding positions, and in formula (2-2), a is an integer of 1 or more and 8 or less, and in formula (2-3), b is an integer of 1 or more and 8 or less, c is an integer of 1 or more and 3 or less, and d is an integer of 1 or more and 8 or less. In formulas (2-1) and (2-3), of the bonding positions * and **, * is the bonding position with the (meth)acryloyloxy group in formula (1).

[0021] The preferred lower limit of the content of the compound having a ring-opened caprolactone skeleton and a polymerizable functional group per 100 parts by mass of the curable resin is 10 parts by mass, and the preferred upper limit is 50 parts by mass. When the content of the compound having a ring-opened caprolactone skeleton and a polymerizable functional group per 100 parts by mass of the curable resin is within this range, the resulting photocurable resin composition has better adhesion to wafers. The more preferred lower limit of the content of the compound having a ring-opened caprolactone skeleton and a polymerizable functional group per 100 parts by mass of the curable resin is 20 parts by mass, and the more preferred upper limit is 40 parts by mass.

[0022] The curable resin preferably contains both the compound having a carboxy group and a polymerizable functional group and the compound having an open-ring skeleton of caprolactone and a polymerizable functional group.

[0023] When the curable resin contains both the compound having a carboxy group and a polymerizable functional group and the compound having a caprolactone ring-opening skeleton and a polymerizable functional group, the content of the compound having a caprolactone ring-opening skeleton and a polymerizable functional group per part by mass of the compound having a carboxy group and a polymerizable functional group is preferably 0.20 parts by mass or less, and preferably 0.85 parts by mass or less. By using this content range of the compound having a caprolactone ring-opening skeleton and a polymerizable functional group per part by mass of the compound having a carboxy group and a polymerizable functional group, the resulting photocurable resin composition exhibits superior adhesion to wafers. The content of the compound having a caprolactone ring-opening skeleton and a polymerizable functional group per part by mass of the compound having a carboxy group and a polymerizable functional group is more preferably 0.25 parts by mass or less, and more preferably 0.80 parts by mass or less.

[0024] Furthermore, when the curable resin contains both the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group, the total content of the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group in the entire curable resin is preferably 80% by mass or more. When the total content of the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group is 80% by mass or more, the resulting photocurable resin composition has superior adhesion to wafers. A more preferred lower limit of the total content of the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group is 90% by mass. Furthermore, the total content of the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened skeleton of caprolactone and a polymerizable functional group in the entire curable resin may be 100 mass %, i.e., the curable resin may contain only the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened skeleton of caprolactone and a polymerizable functional group.

[0025] The curable resin may contain other curable resins than the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group. Examples of the other curable resins include (meth)acrylic compounds other than those included in the compound having a carboxy group and a polymerizable functional group and the compound having a ring-opened caprolactone skeleton and a polymerizable functional group.

[0026] Examples of the other (meth)acrylic compounds include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. Furthermore, from the viewpoint of reactivity, the other (meth)acrylic compounds preferably have two or more (meth)acryloyl groups in one molecule. In this specification, the term "(meth)acrylate" refers to an acrylate or methacrylate, and the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have reacted with (meth)acrylic acid.

[0027] Examples of monofunctional (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and bicyclopentenyl (meth)acrylate. acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, imide (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like.

[0028] Furthermore, examples of the bifunctional (meth)acrylic acid ester compounds include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol. di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethylol dicyclopentadienyl di(meth)acrylate, ethylene oxide-modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polybutadiene diol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and the like.

[0029] Furthermore, examples of the (meth)acrylic acid ester compounds having three or more functional groups include trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, ethylene oxide-added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0030] The epoxy (meth)acrylate may be, for example, one obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0031] Examples of epoxy compounds that can be used as raw materials for synthesizing the above-mentioned epoxy (meth)acrylates include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallyl bisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide-added bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, sulfide type epoxy compounds, diphenyl ether type epoxy compounds, dicyclopentadiene type epoxy compounds, naphthalene type epoxy compounds, phenol novolac type epoxy compounds, o-cresol novolac type epoxy compounds, dicyclopentadiene novolac type epoxy compounds, biphenyl novolac type epoxy compounds, naphthalene phenol novolac type epoxy compounds, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified type epoxy compounds, and glycidyl ester compounds.

[0032] The urethane (meth)acrylate can be obtained, for example, by reacting an isocyanate compound with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin compound.

[0033] Examples of the isocyanate compound that can be used as a raw material for the urethane (meth)acrylate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0034] Furthermore, as the isocyanate compound serving as a raw material for the urethane (meth)acrylate, a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, etc.

[0035] Examples of the (meth)acrylic acid derivatives having a hydroxyl group include hydroxyalkyl mono(meth)acrylates, mono(meth)acrylates of dihydric alcohols, mono(meth)acrylates or di(meth)acrylates of trihydric alcohols, and epoxy (meth)acrylates. Examples of the hydroxyalkyl mono(meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohols include trimethylolethane, trimethylolpropane, and glycerin. Examples of the epoxy (meth)acrylates include bisphenol A-type epoxy (meth)acrylate.

[0036] The preferred lower limit of the content of the curable resin in the photocurable resin composition of the present invention (components excluding the solvent when a solvent is contained) is 5% by mass, and the preferred upper limit is 20% by mass. By having the content of the curable resin in this range, the resulting photocurable resin composition has better adhesion to wafers. The more preferred lower limit of the content of the curable resin is 8% by mass, and the more preferred upper limit is 15% by mass.

[0037] The photocurable resin composition of the present invention preferably further contains a photopolymerization initiator. Examples of the photopolymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-1,2-diphenylethan-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1-(4-methylphenyl)phenylphosphine oxide, and the like. Examples of the photopolymerization initiator include 1-(4-(phenylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime), 2-(acetoxyimino)-1-(4-(4-(2-hydroxyethoxy)phenylthio)phenyl)propan-1-one, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. The photopolymerization initiators may be used alone or in combination of two or more.

[0038] The content of the photopolymerization initiator is preferably 0.1 parts by mass at the lower limit and 10 parts by mass at the upper limit relative to 100 parts by mass of the curable resin. When the content of the photopolymerization initiator is within this range, the resulting photocurable resin composition has better storage stability and photocurability. The more preferred lower limit of the content of the photopolymerization initiator is 1 part by mass, and the more preferred upper limit is 5 parts by mass.

[0039] The photocurable resin composition of the present invention may contain a heat curing agent. However, from the viewpoint of curing the photocurable resin composition of the present invention without carrying out a heating step, it is preferable that the photocurable resin composition does not contain the heat curing agent.

[0040] The photocurable resin composition of the present invention may further contain a thermoplastic resin from the viewpoint of improving adhesion to a wafer by stress relaxation.

[0041] Examples of the thermoplastic resin include polyvinyl butyral, polyurethane, and styrene-ethylene-butylene-styrene block copolymer. Among these, polyvinyl butyral is preferred. The thermoplastic resins may be used alone or in combination of two or more.

[0042] The content of the thermoplastic resin is preferably 1 part by mass at the lower limit and 10 parts by mass at the upper limit relative to 100 parts by mass of the curable resin. By setting the content of the thermoplastic resin within this range, the resulting photocurable resin composition has superior adhesion to wafers. The more preferred lower limit of the content of the thermoplastic resin is 3 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0043] The photocurable resin composition of the present invention may contain a filler, but from the viewpoint of transparency, it is preferable that the composition does not contain the above-mentioned filler.

[0044] The photocurable resin composition of the present invention may contain a solvent. When the photocurable resin composition of the present invention contains a solvent, the solvent is removed after application to the wafer and before the wafers are bonded together to increase the viscosity, thereby preventing the composition from bleeding out when the wafers are bonded together.

[0045] Examples of the solvent include aromatic solvents, alcohol solvents, amide solvents, lactone solvents, carbonate solvents, glyme solvents, and aprotic polar solvents. Examples of the aromatic solvents include benzene, toluene, and xylene. Examples of the alcohol solvents include methanol, ethanol, and isopropyl alcohol. Examples of the amide solvents include N,N'-dimethylformamide, N,N'-dimethylacetamide, and N-methyl-2-pyrrolidone. Examples of the lactone solvents include γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of the carbonate solvents include ethylene carbonate and propylene carbonate. Examples of the glyme solvents include monoglyme, diglyme, and triglyme. Examples of the aprotic polar solvents include dimethyl sulfoxide.

[0046] The content of the solvent is preferably 10 parts by mass or less and 30 parts by mass or less per 100 parts by mass of the curable resin. By using the solvent in this range, the resulting photocurable resin composition has excellent coatability and workability. The lower limit of the content of the solvent is more preferably 15 parts by mass or less and the upper limit is more preferably 20 parts by mass or less.

[0047] Furthermore, the photocurable resin composition of the present invention may contain various known additives, such as a leveling agent, a curing retarder, a reinforcing agent, a viscosity modifier, and an antioxidant, as needed, within the scope of not impairing the object of the present invention.

[0048] The viscosity of the photocurable resin composition of the present invention is adjusted depending on the application method. For example, when the composition is applied by spin coating, the viscosity at 25°C preferably has a lower limit of 0.10 Pa s and an upper limit of 3.0 Pa s, more preferably a lower limit of 1.0 Pa s and an upper limit of 2.0 Pa s. The viscosity can be measured using an E-type viscometer with an appropriate cone plate, by selecting a rotation speed of 1 to 100 rpm as appropriate from the optimum torque number for each viscosity range. An example of the E-type viscometer is the VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.).

[0049] The photocurable resin composition of the present invention is irradiated at a wavelength of 300 nm or more and 400 nm or less and at an illuminance of 100 mW / cm ２ More than 1000mW / cm ２ The irradiation time is 10 seconds or more and 60 seconds or less, and the cumulative light amount is 1500 mJ / cm ２ More than 5000mJ / cm ２ The composition can be suitably cured by irradiating it with the following light.

[0050] Examples of light sources used for irradiating light when curing the photocurable resin composition of the present invention include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, excimer lasers, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, sodium lamps, halogen lamps, xenon lamps, LED lamps, fluorescent lamps, sunlight, electron beam irradiation devices, etc. These light sources may be used alone or in combination of two or more.

[0051] Examples of means for irradiating the photocurable resin composition of the present invention with light include simultaneous irradiation from various light sources, sequential irradiation with a time lag, and a combination of simultaneous irradiation and sequential irradiation, and any of these irradiation means may be used.

[0052] When the photocurable resin composition of the present invention does not contain a solvent, the photocurable resin composition is exposed to a wavelength of 365 nm and an illuminance of 100 mW / cm ２The preferred lower limit of the storage modulus at 25°C of the cured product obtained by irradiating the photocurable resin composition of the present invention with light of a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds is 2.0 GPa. When the photocurable resin composition of the present invention contains a solvent, the solvent is removed from the photocurable resin composition, and then the cured product is cured by irradiating the photocurable resin composition with light of a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds. ２ The preferred lower limit of the storage modulus at 25°C of the cured product obtained by irradiating the cured product with light for 30 seconds is 2.0 GPa. When the storage modulus at 25°C of the cured product is 2.0 GPa or more, the cured product is more effective in suppressing peeling during dicing after bonding wafers (e.g., silicon wafer and glass wafer). The more preferred lower limit of the storage modulus at 25°C of the cured product is 2.5 GPa. There is no particular preferred upper limit of the storage modulus at 25°C of the cured product, but the practical upper limit is 5.0 GPa. The storage modulus is specifically determined by performing dynamic viscoelasticity measurement using a dynamic viscoelasticity measuring device under the conditions of a test piece width of 5 mm, a thickness of 0.50 mm, a tensile mode, a grip width of 25 mm, a heating rate of 10°C / min, a temperature range of 0°C to 150°C, and a frequency of 1 Hz.

[0053] The photocurable resin composition of the present invention preferably has a cured product with a haze upper limit of 1%. Because the haze is 1% or less, the photocurable resin composition of the present invention can be suitably used for laminating wafers (e.g., silicon wafers and glass wafers) in the production of semiconductor components that require high transparency, and can be particularly suitably used in the production of CMOS image sensors and the like. A more preferred upper limit of the haze is 0.5%. The haze refers to the ratio of diffuse transmitted light to total transmitted light, and can be measured, for example, using a spectrometer such as a COH-7700 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0054] The photocurable resin composition of the present invention is suitably used for bonding wafers (for example, a silicon wafer and a glass wafer), and is particularly suitable for use in the wafer bonding step in the manufacture of CMOS image sensors.

[0055] According to the present invention, it is possible to provide a photocurable resin composition that can suppress seepage when wafers are bonded together and can improve adhesion to wafers by heating the cured product at a low temperature.

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0057] Synthesis Example 1: 105 parts by mass of 2-hydroxyethyl acrylate, 114 parts by mass of ε-caprolactone, and 0.2 parts by mass of hydroquinone as a polymerization inhibitor were added to a reaction flask and stirred using a mantle heater at 90°C for 5 hours, after which 148 parts by mass of phthalic anhydride was added and stirred for an additional 5 hours. Next, 170 parts by mass of bisphenol A diglycidyl ether was added to the resulting reaction product and stirred at 90°C for 5 hours to obtain a curable resin mixture. １ H-NMR and １３ By C-NMR, it was confirmed that the obtained curable resin mixture contained the compound represented by the above formula (1) (R １ is hydrogen, R ２ is an ethylene group, R ３ It was confirmed that the copolymer contained a 1,2-phenylene group, X an open ring structure of ε-caprolactone, n was 1.01 (average value), and Ep a structure derived from bisphenol A diglycidyl ether.

[0058] (Examples 1 to 4 and Comparative Examples 1 to 6) Photocurable resin compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were prepared by stirring and mixing the materials using a stirring mixer according to the blending ratios listed in Table 1. Awatori Rentaro ARE-310 (manufactured by Thinky Corporation) was used as the stirring mixer. Note that "CN704" in Table 1 is a bifunctional polyester acrylate oligomer having a carboxy group. Each of the obtained photocurable resin compositions was applied to a release PET film ("PET5011" manufactured by Lintec Corporation) using a bar coater (manufactured by RD specialities, No. 37) to a thickness of 100 μm, and then heated at 80°C for 5 minutes to dry, thereby removing the solvent. Each photocurable resin composition after solvent removal was measured using a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２A cured product was obtained by irradiating the cured product with light of 1000 nm for 30 seconds. Dynamic viscoelasticity measurements were performed on the resulting cured product using a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under the following conditions: test piece width 5 mm, thickness 0.50 mm, tensile mode, grip width 25 mm, heating rate 10°C / min, temperature range 0°C to 150°C, and frequency 1 Hz. The temperature at which the loss tangent (tan δ) was maximized was determined as the glass transition temperature, and this is shown in Table 1. The storage modulus at 25°C is also shown in Table 1.

[0059] <Evaluation> The photocurable resin compositions obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0060] (Coatability and Low Exudation) For each photocurable resin composition obtained, the viscosity (value 3 minutes after the start of rotation) was measured using an E-type viscometer with a CP1 type cone plate at 25°C and 5 rpm. A VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used as the E-type viscometer. The coatability (coatability by spin coating) was evaluated by assigning an "A" if the viscosity was 3.0 Pa·s or less and an "B" if the viscosity exceeded 3.0 Pa·s. Each photocurable resin composition obtained was coated onto a release PET film ("PET5011" manufactured by Lintec Corporation) to a thickness of 100 μm using a bar coater (manufactured by RD specialities, No. 37), and the solvent was removed by heating and drying at 80°C for 5 minutes. The viscosity of each photocurable resin composition after solvent removal was measured in the same manner. The low exudation property was evaluated by rating "A" when the viscosity was 30.0 Pa·s or more, and rating "B" when the viscosity was less than 30.0 Pa·s.

[0061] (Adhesion to Glass (Wafer)) Each of the obtained photocurable resin compositions was dropped onto one of two glass substrates (glass substrate A), and then the other glass substrate (glass substrate B) was overlapped with glass substrate A in a cross shape so that the diameter of the photocurable resin composition sandwiched between glass substrates A and B was 3 mm. Next, using a metal halide lamp, the photocurable resin composition was irradiated with light at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２The photocurable resin composition was cured by irradiating the test piece with light of 1000 kJ / cm for 30 seconds, thereby obtaining a test piece. The test piece obtained was placed with glass substrate B facing downward, and both ends of glass substrate A were fixed from below. Both ends of glass substrate B were compressed from above using a precision universal testing machine at 25°C and a speed of 5 mm / min, thereby measuring the adhesive strength between glass substrate A and glass substrate B. An Autograph AG-Xplus (manufactured by Shimadzu Corporation) was used as the precision universal testing machine. A test piece prepared in the same manner was heated at 80°C for 30 minutes, and then the adhesive strength between glass substrate A and glass substrate B was measured in the same manner. The adhesive strength measured for the test piece after heating at 80°C for 30 minutes was 6.0 kgf / cm ２ If it is 6.0 kgf / cm or more, it is "A" ２ If the adhesion was less than 100%, the adhesion to the glass (wafer) was evaluated as "B".

[0062]

[0063] According to the present invention, it is possible to provide a photocurable resin composition that can suppress seepage when wafers are bonded together and can improve adhesion to wafers by heating the cured product at a low temperature.

Claims

1. A photocurable resin composition for use by coating a wafer, comprising a curable resin, and when the photocurable resin composition does not contain a solvent, the photocurable resin composition is irradiated with a light having a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ the glass transition temperature of the cured product obtained by irradiating the photocurable resin composition with light having a wavelength of 365 nm and an illuminance of 100 mW / cm for 30 seconds is 80° C. or lower, and when the photocurable resin composition contains a solvent, the solvent is removed from the photocurable resin composition, and then the photocurable resin composition is irradiated with light having a wavelength of 365 nm and an illuminance of 100 mW / cm for ２ 1. A photocurable resin composition, characterized in that a cured product obtained by irradiating the composition with light of 100 nm for 30 seconds has a glass transition temperature of 80° C. or lower.

2. The photocurable resin composition according to claim 1, wherein the curable resin contains a compound having a carboxy group and a polymerizable functional group.

3. A photocurable resin composition according to claim 1 or 2, wherein the curable resin contains a compound having a ring-opened caprolactone skeleton and a polymerizable functional group.

4. A photocurable resin composition according to claim 1, wherein the curable resin comprises a compound having a carboxy group and a polymerizable functional group, and a compound having a ring-open skeleton of caprolactone and a polymerizable functional group, the content of the compound having the ring-open skeleton of caprolactone and a polymerizable functional group per 1 part by mass of the compound having the carboxy group and a polymerizable functional group is 0.20 parts by mass or more and 0.85 parts by mass or less, and the total content of the compound having the carboxy group and a polymerizable functional group and the compound having the ring-open skeleton of caprolactone and a polymerizable functional group in the entire curable resin is 80% by mass or more.

5. The photocurable resin composition according to claim 1, 2, 3 or 4, which is used in a wafer lamination process in the manufacture of a CMOS image sensor.

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