Adhesive layer forming material, adhesive sheet intermediate, method for producing adhesive sheet and adhesive sheet

Abstract

To provide an adhesive sheet which reduces the amount used of a solvent and has sufficient adhesion with an adherend even in a step using water.SOLUTION: There is provided an adhesive layer forming material which comprises (A) a polyfunctional epoxy monomer, a thermal acid generator and a photopolymerization initiator. Further, there is provided an adhesive sheet intermediate which includes an adhesive precursor layer and a base material, wherein the adhesive precursor layer is formed from an adhesive layer forming material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive layer forming material, an adhesive sheet intermediate, a method for manufacturing an adhesive sheet, and an adhesive sheet.

Background Art

[0002] Adhesive sheets are widely used for the purpose of protecting the surface of an adherend and fixing it. For example, in the processing steps of a semiconductor wafer, it is used to appropriately hold the semiconductor wafer, which is the adherend, in the back grinding step and the dicing step. In recent years, chip miniaturization and thinning have been progressing, and an adhesive force that can appropriately hold the semiconductor wafer even when the semiconductor wafer is thinly ground during processing is required. An adhesive sheet typically consists of an adhesive layer and a base material (for example, Patent Document 1). In the manufacturing process of an adhesive sheet, a solvent is used in the manufacturing stage of the adhesive and the formation stage of the adhesive layer. In recent years, in order to reduce the environmental load, efforts have been made to reduce the amount of solvent used. For example, an adhesive sheet using an aqueous adhesive has been proposed (Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the processing step of a semiconductor wafer, water can be used to suppress the rise in temperature. An adhesive sheet using an aqueous adhesive may float from the adherend in the step of using water and may not be able to hold the adherend sufficiently. Therefore, there is a demand for an adhesive sheet that reduces the amount of solvent used and has sufficient adhesion to the adherend even in the step of using water. Further, in order to suppress adhesive residue at the time of peeling, an adhesive sheet is required that exhibits excellent adhesive strength before ultraviolet irradiation and can be peeled from the adherend without adhesive residue after ultraviolet irradiation.

Means for Solving the Problems

[0005] 1. The adhesive layer forming material of an embodiment of the present invention contains (A) a polyfunctional epoxy monomer, a thermal acid generator, and a photopolymerization initiator. 2. In the adhesive layer forming material described in 1 above, the epoxy equivalent of the polyfunctional epoxy monomer (A) may be 250 g / eq or more. 3. The adhesive layer forming material described in 1 or 2 above may further contain (B) a compound having an epoxy group and a (meth)acryloyl group. 4. The adhesive layer forming material described in any one of 1 to 3 above may further contain (C) a polyfunctional acrylic monomer. 5. In the adhesive layer forming material described in any one of 1 to 4 above, the thermal acid generator may be a sulfonium salt-based thermal acid generator. 6. In another embodiment of the present invention, an adhesive sheet intermediate is provided. This adhesive sheet intermediate includes an adhesive precursor layer formed using the adhesive layer forming material described in any one of 1 to 5 above and a base material. 7. In still another embodiment of the present invention, a method for manufacturing an adhesive sheet is provided. This manufacturing method includes forming an adhesive precursor layer on a base material using the adhesive layer forming material described in any one of 1 to 5 above to form an adhesive sheet intermediate, and heating the adhesive sheet intermediate. 8. In still another embodiment of the present invention, an adhesive sheet is provided. This adhesive sheet includes an adhesive layer containing a cationic polymer having a (meth)acryloyl group in a side chain and a photopolymerization initiator, and a base material. 9. The pressure-sensitive adhesive sheet according to 8 above may be used for semiconductor processing.

Advantages of the Invention

[0006] According to the pressure-sensitive adhesive layer forming material, the pressure-sensitive adhesive sheet intermediate, and the method for manufacturing the pressure-sensitive adhesive sheet of the embodiment of the present invention, it is possible to reduce the amount of solvent used and provide a pressure-sensitive adhesive sheet having sufficient adhesion to an adherend even in a step using water. The pressure-sensitive adhesive sheet of the embodiment of the present invention can provide a pressure-sensitive adhesive sheet that exhibits excellent adhesive force before ultraviolet irradiation and can be peeled off from the adherend without adhesive residue after ultraviolet irradiation.

Brief Description of the Drawings

[0007]

Figure 1

Modes for Carrying Out the Invention

[0008] A. Pressure-sensitive adhesive layer forming material The pressure-sensitive adhesive layer forming material of the embodiment of the present invention contains a polyfunctional epoxy monomer (A), a thermal acid generator, and a photopolymerization initiator. The pressure-sensitive adhesive layer forming material of the embodiment of the present invention has a low viscosity (for example, 20 Pa·s or less at 25°C) and can be applied to a substrate without using a diluent such as an organic solvent. After being applied to an adherend, a pressure-sensitive adhesive layer can be formed on the adherend by heating at any appropriate temperature. Therefore, the amount of organic solvent used can be reduced. Further, after applying the pressure-sensitive adhesive layer forming material to an arbitrary appropriate substrate to form a pressure-sensitive adhesive precursor layer and then heating at any appropriate temperature, a pressure-sensitive adhesive sheet can be obtained. As described above, the pressure-sensitive adhesive layer forming material of the embodiment of the present invention contains a polyfunctional epoxy monomer (A) and a thermal acid generator. By heating the layer formed using the pressure-sensitive adhesive layer forming material, an acid is generated from the thermal acid generator, and the polyfunctional epoxy monomer (A) is polymerized on the adherend or the substrate to prepare a pressure-sensitive adhesive containing an epoxy resin on the adherend or the substrate. Further, the pressure-sensitive adhesive layer forming material of the embodiment of the present invention is composed of a monomer component for polymerizing the polymer contained in the pressure-sensitive adhesive composition and an additive that can be contained in the pressure-sensitive adhesive after passing through a subsequent heating step, and substantially does not contain an organic solvent. According to the embodiment of the present invention, a pressure-sensitive adhesive layer forming material capable of reducing the amount of organic solvent used in the manufacturing process and manufacturing a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet can be provided. Furthermore, since the pressure-sensitive adhesive layer forming material of the embodiment of the present invention is not prepared in an aqueous system, for example, when used as a material for forming the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet used in a processing step of a semiconductor wafer, even when subjected to a working step using water, a pressure-sensitive adhesive sheet having sufficient adhesion to the adherend can be provided even in a step using water.

[0009] A-1. Monomer component A-1-1. Polyfunctional epoxy monomer (A) As the polyfunctional epoxy monomer (A), any suitable epoxy monomer having two or more functional groups is used. Specifically, bifunctional ones obtained by epoxidizing bisphenol compounds such as bisphenol A, bisphenol C, bisphenol E, bisphenol F, biphenol or their derivatives, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, diols having an alicyclic structure such as cyclohexanediol, cyclohexanedimethanol, and cyclohexanedietanol or their derivatives, aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, and decanediol or their derivatives, trifunctional ones having a trihydroxyphenylmethane skeleton or an aminophenol skeleton, polyfunctional ones obtained by epoxidizing phenol novolak resin, cresol novolak resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, etc. are mentioned. The polyfunctional epoxy monomer is preferably a bisphenol compound such as bisphenol A, bisphenol C, bisphenol E, bisphenol F or their derivatives, more preferably bisphenol A and bisphenol F. The polyfunctional epoxy monomer may be used alone or in combination of two or more.

[0010] The epoxy equivalent of the polyfunctional epoxy monomer is preferably 250 g / eq or more, more preferably 300 g / eq or more, still more preferably 350 g / eq or more, and particularly preferably 400 g / eq or more. The epoxy equivalent of the polyfunctional epoxy monomer is, for example, 1500 g / eq or less. If the epoxy equivalent of the polyfunctional epoxy monomer is within the above range, the distance between crosslinking points of the polymer obtained by cationic polymerization becomes long, and a sticky sheet can be obtained.

[0011] The polyfunctional epoxy monomer (A) is used in any suitable ratio. The content ratio of the polyfunctional epoxy monomer (A) is preferably 60% by weight to 95% by weight, more preferably 65% by weight to 90% by weight, and still more preferably 70% by weight to 85% by weight out of the total 100% by weight of all monomer components. If the content ratio of the polyfunctional epoxy monomer is within the above range, an adhesive layer forming material capable of forming an adhesive layer having sufficient adhesiveness on a base material or an adherend can be obtained.

[0012] A-1-2. Compound (B) having an epoxy group and a (meth)acryloyl group The adhesive layer forming material preferably further contains a compound (B) having an epoxy group and a (meth)acryloyl group. By using a compound having an epoxy group and a (meth)acryloyl group, a (meth)acryloyl group can be introduced into the side chain of the polymer obtained by subsequent cationic polymerization, and an adhesive layer that can be lightly peeled off after ultraviolet irradiation can be formed. Also, contamination of the adherend can be suppressed. As described above, the adhesive layer forming material of the embodiment of the present invention contains a polyfunctional epoxy monomer (A) as a monomer component and an arbitrary polyfunctional acrylic monomer (C) as a monomer component. For a compound having both an epoxy group and a (meth)acryloyl group as a functional group, it is defined as a compound (B) having an epoxy group and a (meth)acryloyl group, and is not included in the polyfunctional epoxy monomer (A) and the polyfunctional acrylic monomer (C). The compound (B) having an epoxy group and a (meth)acryloyl group is preferably a compound having one epoxy group and one (meth)acryloyl group.

[0013] As the compound (B) having an epoxy group and a (meth)acryloyl group, any suitable compound having an epoxy group and a (meth)acryloyl group can be used. Specifically, examples include glycidyl ether of 4-hydroxybutyl acrylate, bisphenol A epoxy partial acrylate, bisphenol F epoxy partial acrylate, and the like. Preferably, bisphenol A epoxy partial acrylate and bisphenol F epoxy partial acrylate are mentioned. These compounds (B) having an epoxy group and a (meth)acryloyl group have good compatibility with the polyfunctional epoxy monomer (A) and similar cation reactivity to the polyfunctional epoxy monomer (A), so that the (meth)acryloyl group can be uniformly introduced into the base polymer that can be formed in the subsequent reaction. Only one kind of the compound (B) having an epoxy group and a (meth)acryloyl group may be used, or two or more kinds may be used in combination.

[0014] In one embodiment, as the compound (B) having an epoxy group and a (meth)acryloyl group, an oligomer such as epoxy acrylate may be used. When using an oligomer, the epoxy equivalent of the oligomer is preferably 100 to 1000, more preferably 100 to 500, and even more preferably 100 to 300. If the epoxy equivalent is within the above range, the distance between the (meth)acryloyl groups introduced into the side chain of the base polymer becomes smaller, and light peeling after ultraviolet irradiation may become easier.

[0015] The compound (B) having an epoxy group and a (meth)acryloyl group is used in any suitable ratio. The content ratio of the compound (B) having an epoxy group and a (meth)acryloyl group is preferably 5% to 40% by weight, more preferably 5% to 35% by weight, and even more preferably 5% to 30% by weight out of the total 100% by weight of all monomer components. If the content ratio of the compound (B) having an epoxy group and a (meth)acryloyl group is within the above range, a sufficient amount of the (meth)acryloyl group can be introduced into the side chain of the base polymer, and light peeling after ultraviolet irradiation may become easier.

[0016] A-1-3. Polyfunctional Acrylic Monomer (C) The pressure-sensitive adhesive layer forming material preferably further contains a polyfunctional acrylic monomer (C). If the polyfunctional acrylic monomer (C) is further used, a pressure-sensitive adhesive layer that can be lightly peeled off after ultraviolet irradiation can be formed. As the polyfunctional acrylic monomer, any suitable acrylic monomer can be used. For example, bifunctional (meth)acrylic monomers such as 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, neopentyl triethylene glycol di(meth)acrylate, etc., and pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc. can be mentioned. Only one kind of polyfunctional acrylic monomer may be used, or two or more kinds may be used in combination. In this specification, (meth)acrylic refers to acrylic and / or methacrylic.

[0017] The polyfunctional acrylic monomer (C) is used in any suitable ratio. The content ratio of the polyfunctional acrylic monomer (C) is preferably 2% by weight to 20% by weight, more preferably 4% by weight to 18% by weight, and still more preferably 5% by weight to 15% by weight out of the total 100% by weight of all monomer components. If the content ratio of the polyfunctional acrylic monomer (C) is within the above range, a pressure-sensitive adhesive layer forming material that has sufficient adhesive strength on the base material or adherend and can form a pressure-sensitive adhesive layer that can be lightly peeled off after ultraviolet irradiation can be obtained.

[0018] A-1-4. Other Monomers The pressure-sensitive adhesive layer forming material of the embodiment of the present invention may further contain any suitable monomer component. For example, monomers having one epoxy group can be mentioned. These monomers may be used alone or in combination of two or more. Other monomers are used in any suitable content ratio.

[0019] A-2. Thermal acid generator As the thermal acid generator, any compound that generates an acid upon heating may be used, and any appropriate compound can be employed. For example, onium salt-based thermal acid generators such as sulfonium salts, ammonium salts, and phosphonium salts, and ester compound-based acid generators such as carboxylic acid ester compounds, sulfonic acid ester compounds, and phosphate ester compounds can be mentioned. Preferably, a sulfonium salt-based thermal acid generator is used. The thermal acid generator may be used alone or in combination of two or more.

[0020] The acid generation temperature of the thermal acid generator is preferably 50°C to 150°C, more preferably 50°C to 120°C, and even more preferably 80°C to 120°C. If the acid generation temperature is within the above range, the polymerization of the epoxy resin can be carried out well on the adherend or the substrate.

[0021] Commercially available products may be used as the thermal acid generator. For example, products such as the Sun-Aid SI series with the trade name "Sun-Aid SI 80L" manufactured by Sanshin Chemical Industry Co., Ltd., the TA-100 series with the trade name "TA-100" manufactured by San-Apro Ltd., and the IK-1 series such as "IK-1" can be mentioned.

[0022] The thermal acid generator can be used in any appropriate content. The content of the thermal acid generator is preferably 0.5 parts by weight to 20 parts by weight, more preferably 1 part by weight to 15 parts by weight, and even more preferably 1.5 parts by weight to 10 parts by weight based on 100 parts by weight in total of the monomer components. If the content of the thermal acid generator is within the above range, the polymerization of the epoxy resin can be carried out well on the adherend or the substrate.

[0023] A-3. Photoinitiator The pressure-sensitive adhesive layer forming material of the embodiment of the present invention further contains a photoinitiator. If a photoinitiator is further contained, an ultraviolet curable pressure-sensitive adhesive layer can be formed on the adherend or the substrate. For an ultraviolet curable pressure-sensitive adhesive layer, after ultraviolet irradiation, the pressure-sensitive adhesive layer (or the pressure-sensitive adhesive sheet on which the pressure-sensitive adhesive layer is formed) can be peeled off from the adherend without adhesive residue.

[0024] As the photoinitiator, any suitable initiator can be used. Examples of photoinitiators include acylphosphine oxide-based photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate and (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; α-ketol-based compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenylketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropan-1; benzoin ether-based compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; ketal-based compounds such as benzyldimethylketal; aromatic sulfonyl chloride-based compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime-based compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone-based compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone-based compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonates; α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1, and the like. The photoinitiator may be used alone or in combination of two or more.

[0025] As the photoinitiator, commercially available products may be used. Preferably, a photoinitiator that is liquid at room temperature is used. For example, products named "Omnirad TPO-L", "Omnirad 500", "Omnirad MBF", etc. manufactured by IGM Resins can be mentioned. For example, if Omnirad TPO-L is used as the photoinitiator, it can be cured well even when using a light source such as an LED lamp.

[0026] The photoinitiator can be used in any appropriate amount. The content of the photoinitiator is preferably 0.5 parts by weight to 20 parts by weight, more preferably 1 part by weight to 10 parts by weight, based on 100 parts by weight in total of the monomer components. If the content of the photoinitiator is less than 0.5 parts by weight, there is a risk of insufficient curing during ultraviolet irradiation.

[0027] A-4. Additives The pressure-sensitive adhesive layer forming material may further use any appropriate additive as required. Examples of the additive include a crosslinking agent, a catalyst (e.g., a platinum catalyst), a tackifier, a plasticizer, a pigment, a dye, a filler, an antioxidant, a conductive material, an ultraviolet absorber, a light stabilizer, a release regulator, a softening agent, a flame retardant, an epoxy diluent, etc. The additive is used in any appropriate amount according to the purpose.

[0028] A-5. Preparation method The pressure-sensitive adhesive layer forming material can be prepared by any appropriate method. For example, it can be prepared by mixing a polyfunctional epoxy monomer, a thermal acid generator, a photoinitiator, any polyfunctional (meth)acrylic monomer, and an additive.

[0029] B. Pressure-sensitive adhesive sheet intermediate FIG. 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet intermediate according to an embodiment of the present invention. The pressure-sensitive adhesive sheet intermediate 100 includes a base material 10 and a pressure-sensitive adhesive precursor layer 20. The pressure-sensitive adhesive precursor layer 20 is formed using the pressure-sensitive adhesive layer forming material described above. As described above, the pressure-sensitive adhesive layer forming material has a low viscosity and can be easily applied to the base material without adjusting the viscosity using a diluent such as an organic solvent. Therefore, the amount of the organic solvent used in the manufacturing process of the pressure-sensitive adhesive sheet can be reduced. Further, since it is not a water-based pressure-sensitive adhesive, for example, when used as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet used in the processing step of the semiconductor wafer, even when subjected to a working step using water, a pressure-sensitive adhesive sheet having sufficient adhesion to the adherend can be provided even in the step using water.

[0030] B-1. Pressure-Sensitive Adhesive Precursor Layer As described above, the pressure-sensitive adhesive precursor layer is formed using the pressure-sensitive adhesive layer forming material described in Item A.

[0031] The thickness of the pressure-sensitive adhesive precursor layer can be set to any appropriate value. The thickness of the pressure-sensitive adhesive precursor layer is preferably 2 μm to 200 μm, more preferably 3 μm to 150 μm, and even more preferably 5 μm to 100 μm. If the thickness of the pressure-sensitive adhesive precursor layer is within the above range, the finally formed pressure-sensitive adhesive layer can exhibit excellent adhesive force to the adherend.

[0032] B-2. Base Material The base material can be composed of any suitable resin. Specific examples of the resin constituting the base material include polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluorine-based resins, polyethers, polystyrene resins such as polystyrene, polycarbonate, polyethersulfone, polyetheretherketone, etc. Preferably, it is a polyester resin. Since these resins transmit ultraviolet rays, a pressure-sensitive adhesive sheet having light peelability can finally be obtained by ultraviolet irradiation.

[0033] The base material may further contain other components as long as the effects of the present invention are not impaired. Examples of other components include antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, antistatic agents, etc. The type and amount of use of other components can be used in any appropriate amount according to the purpose.

[0034] The thickness of the base material can be set to any appropriate value. The thickness of the base material is preferably 30 μm to 200 μm, more preferably 40 μm to 180 μm, and even more preferably 45 μm to 180 μm.

[0035] B-3. Manufacturing method The pressure-sensitive adhesive sheet intermediate can be manufactured by any appropriate method. For example, a pressure-sensitive adhesive sheet intermediate can be obtained by applying a pressure-sensitive adhesive layer forming material on a base material to form a pressure-sensitive adhesive precursor layer.

[0036] As methods for applying the pressure-sensitive adhesive layer forming material, various methods such as bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. can be adopted.

[0037] C. Method for manufacturing the pressure-sensitive adhesive sheet The method for manufacturing the pressure-sensitive adhesive sheet according to the embodiment of the present invention includes forming a pressure-sensitive adhesive precursor layer using the pressure-sensitive adhesive layer forming material to form a pressure-sensitive adhesive sheet intermediate, and heating the pressure-sensitive adhesive sheet intermediate. As described above, the pressure-sensitive adhesive precursor layer is formed using the pressure-sensitive adhesive layer forming material. Since the pressure-sensitive adhesive layer forming material does not contain a resin that becomes the base polymer of the pressure-sensitive adhesive, the pressure-sensitive adhesive precursor layer can be formed without using a diluent such as an organic solvent. When the pressure-sensitive adhesive sheet intermediate including this pressure-sensitive adhesive precursor layer is heated, a cationic polymer of an epoxy monomer that becomes the base polymer can be formed within the pressure-sensitive adhesive precursor layer. More specifically, heat causes an acid to be generated from the heat acid generator, and the polyfunctional epoxy monomer and any polyfunctional (meth)acrylic monomer contained in the pressure-sensitive adhesive precursor layer can undergo cationic polymerization. As a result, a pressure-sensitive adhesive layer including a cationic polymer of an epoxy monomer as the base polymer (when including a polyfunctional (meth)acrylic monomer, a cationic polymer of an epoxy monomer having a (meth)acryloyl group in the side chain) and a photoinitiator can be formed on the base material. This pressure-sensitive adhesive layer has excellent adhesion to the adherend before ultraviolet irradiation and can be peeled off from the adherend without residue after ultraviolet irradiation. Therefore, for example, a pressure-sensitive adhesive sheet suitable for semiconductor wafer processing can be obtained.

[0038] C-1. Preparation of the pressure-sensitive adhesive sheet intermediate As described in section B above, a pressure-sensitive adhesive precursor layer is formed on the base material using the pressure-sensitive adhesive layer forming material. As described above, the pressure-sensitive adhesive layer forming material has a low viscosity (for example, 20 Pa·s or less at 25°C), and the pressure-sensitive adhesive precursor layer can be formed on the base material without using a diluent such as an organic solvent. In the pressure-sensitive adhesive sheet intermediate, the pressure-sensitive adhesive precursor layer can be a coating film of the pressure-sensitive adhesive layer forming material.

[0039] C-2. Heating Step The pressure-sensitive adhesive sheet intermediate having a substrate and a pressure-sensitive adhesive precursor layer is subjected to a heating step. As described above, an acid is generated from the thermal acid generator in the heating step, and a pressure-sensitive adhesive layer containing a cationic polymer of an epoxy monomer can be formed on the substrate. The heating step is preferably performed in a light-shielded state. By performing it in a light-shielded state, it is possible to suppress the reaction of the photoinitiator contained in the pressure-sensitive adhesive precursor layer and the reaction of the (meth)acryloyl group of the polymer contained in the pressure-sensitive adhesive layer of the resulting pressure-sensitive adhesive sheet.

[0040] The heating may be at any temperature at which an acid can be generated from the thermal acid generator, and is performed at any appropriate temperature. The heating temperature is preferably 100°C to 200°C, more preferably 100°C to 150°C, and even more preferably 120°C to 150°C. The heating time can be performed for any appropriate time. The heating time is preferably 1 minute to 10 minutes, more preferably 2 minutes to 10 minutes, and even more preferably 2 minutes to 5 minutes.

[0041] Any appropriate means can be used as the heating means. For example, a dryer, an oven, etc. can be mentioned.

[0042] D. Pressure-Sensitive Adhesive Sheet The pressure-sensitive adhesive sheet of the embodiment of the present invention contains a cationic polymer of an epoxy monomer having a (meth)acryloyl group in the side chain and a photoinitiator. The pressure-sensitive adhesive sheet of the embodiment of the present invention can be manufactured using the pressure-sensitive adhesive sheet intermediate in which the pressure-sensitive adhesive precursor layer is formed using the above-described pressure-sensitive adhesive layer forming material. The pressure-sensitive adhesive sheet of the embodiment of the present invention can have excellent adhesion to an adherend before ultraviolet irradiation. Further, after ultraviolet irradiation, the (meth)acryloyl group possessed by the cationic polymer of the epoxy monomer in the side chain reacts with the photoinitiator, and the adhesive force decreases, and it can be peeled off from the adherend without adhesive residue. Also, as described above, the pressure-sensitive adhesive layer forming material substantially does not contain an organic solvent. Therefore, problems that may occur due to the pressure-sensitive adhesive layer containing an organic solvent (for example, deterioration of the adherend due to the solvent volatilized from the pressure-sensitive adhesive layer, abnormal odor) can also be suppressed.

[0043] The adhesive sheet preferably has an adhesive force to the silicon wafer of the adhesive sheet before ultraviolet irradiation of 1.0 N / 20 mm or more, more preferably 1.5 N / 20 mm or more, and even more preferably 2.0 N / 20 mm or more. If the adhesive force to the silicon wafer before ultraviolet irradiation is within the above range, it has excellent adhesion to the adherend. Also, the adhesive force to the silicon wafer is, for example, 15 N / 20 mm or less. In this specification, the adhesive force to the silicon wafer refers to the adhesive force measured by the following method. The adhesive sheet is cut into a width of 20 mm and a length of 80 mm, and is pressure-bonded to the mirror surface of a silicon mirror wafer by reciprocating a hand roller once in an atmosphere of 23°C and left standing at 23°C for 30 minutes. Then, the force required to peel off the adhesive sheet is measured by performing a 180° peel test at a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH.

[0044] The adhesive sheet preferably has an adhesive force to the silicon wafer of the adhesive sheet after ultraviolet irradiation such that the integrated light amount is 500 mJ / cm 2 is 2 N / 20 mm or less, more preferably 1 N / 20 mm or less, and even more preferably 0.5 N / 20 mm or less. If the adhesive force to the silicon wafer after ultraviolet irradiation is within the above range, it has easy peelability. The smaller the adhesive force after ultraviolet irradiation, the more preferable. In this specification, the adhesive force to the silicon wafer of the adhesive sheet after ultraviolet irradiation such that the integrated light amount is 500 mJ / cm 2 refers to the value measured by the following method. The adhesive sheet is cut into a width of 20 mm and a length of 80 mm, and is pressure-bonded to the mirror surface of a silicon mirror wafer by reciprocating a hand roller once in an atmosphere of 23°C and left standing at 23°C for 30 minutes. Then, ultraviolet light (UV) is irradiated from the adhesive sheet surface side so that the integrated light amount is 500 mJ / cm 2 (in terms of 365 nm). Next, the force required to peel off the adhesive sheet is measured by performing a 180° peel test under the conditions of an atmosphere of 23°C and 50% RH and a tensile speed of 300 mm / min.

[0045] The thickness of the pressure-sensitive adhesive sheet obtained by the manufacturing method of the embodiment of the present invention can be set to any appropriate thickness. The thickness of the pressure-sensitive adhesive sheet is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, and still more preferably 50 μm to 200 μm.

[0046] The thickness of the pressure-sensitive adhesive layer can be set to any appropriate value. The thickness of the pressure-sensitive adhesive layer is preferably 2 μm to 200 μm, more preferably 3 μm to 150 μm, and still more preferably 5 μm to 100 μm. If the thickness of the pressure-sensitive adhesive layer is within the above range, excellent adhesive force can be exhibited with respect to the adherend.

[0047] E. Use of the pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet obtained by the manufacturing method of the embodiment of the present invention can be suitably used in the manufacturing process of semiconductor wafers. For example, it can be used as a pressure-sensitive adhesive sheet for semiconductor wafer processing such as dicing tape and back grinding tape. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the embodiment of the present invention is not a layer formed from an aqueous pressure-sensitive adhesive. Therefore, even when used in an operation performed using water such as a back grinding process, the adhesion to the adherend can be maintained.

Examples

[0048] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are based on weight unless otherwise specified.

[0049] [Examples 1 to 7] (1) Preparation of the pressure-sensitive adhesive layer forming material The materials were mixed in the contents shown in Table 1 to obtain a pressure-sensitive adhesive layer forming material. (2) Production of the pressure-sensitive adhesive sheet intermediate On the corona-treated surface of a 50-μm-thick polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., trade name "Lumirror #50 S-105") with corona treatment on one side, an adhesive layer forming material was applied, and in a state where ultraviolet rays were blocked, it was dried in a dryer at 130 °C for 3 minutes to form an adhesive precursor layer with a thickness of 30 μm. Next, the PET was laminated to the release-treated surface of a PET release liner (manufactured by Mitsubishi Chemical Corporation, trade name "Diafoil MRF38") with a hand roller to obtain an adhesive sheet intermediate. (3) Preparation of Adhesive Sheet Next, the adhesive sheet intermediate was left in a dryer set at 50 °C for 48 hours in a light-shielded state. Then, it was taken out of the dryer to obtain an adhesive sheet.

[0050] (Comparative Examples 1 and 2) An attempt was made to prepare an adhesive sheet in the same manner as in Examples 1 to 7. In Comparative Examples 1 and 2, the layer formed from the adhesive precursor layer did not have adhesiveness, and an adhesive sheet could not be obtained.

[0051] (Comparative Example 3) Into a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirring device, 180 parts by weight of water, 65 parts by weight of 2-ethylhexyl acrylate (2EHA), 35 parts by weight of butyl methacrylate (BMA), 2 parts by weight of acrylic acid (AA), and 2 parts by weight of a surfactant (manufactured by Kao Corporation, trade name "Latemul E-118B") were mixed and stirred with a homomixer to obtain a monomer solution that was emulsified. Next, it was purged with nitrogen for 1 hour while stirring. In the subsequent reaction, the internal bath temperature during polymerization was controlled at 60 °C. Then, 0.05 part by weight of a water-soluble azo initiator (manufactured by Fuji Film Wako Pure Chemical Corporation, trade name "VA-057") was added to initiate polymerization, and it was heated for 5 hours to obtain a water-dispersible acrylic polymer. To the obtained water-dispersible acrylic polymer, 1 part by weight of a crosslinking agent (manufactured by Nippon Shokubai Co., Ltd.: "Epocros WS 500"), 50 parts by weight of a UV-curing resin (manufactured by Ube Industries, Ltd., "ETERNACOLL UW-9102"), and 3 parts by weight of a photoinitiator (manufactured by IGM Resins B.V.: trade name "Omnirad 500") were added and mixed. After that, it was neutralized with 10% aqueous ammonia to obtain a water-dispersed solution. The obtained adhesive solution was applied to the silicone release-treated surface of a polyester film (thickness 38 μm) subjected to silicone release treatment so that the dried thickness would be 30 μm, and dried at 125°C for 3 minutes to form an adhesive layer. The corona-treated surface of a 50-μm-thick PET subjected to corona treatment was bonded to the adhesive surface of the adhesive layer to transfer the adhesive layer, and an adhesive sheet was obtained.

[0052] (Comparative Example 4) Into a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirring device, 300 parts by weight of ethyl acetate, 83 parts by weight of butyl acrylate (BA), 15 parts by weight of acrylonitrile (AN), and 2 parts by weight of acrylic acid (AA) were charged, and nitrogen substitution was carried out for 1 hour while stirring. In the subsequent reaction, the internal bath temperature during polymerization was controlled at 60°C. Here, 0.2 part by weight of an azo initiator (azobisisobutyronitrile (AIBN)) was added to initiate polymerization, and an acrylic polymer was produced by heating for 5 hours. To the obtained acrylic polymer, 0.1 part by weight of a crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD C"), 20 parts by weight of a UV-curing resin (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA"), and 2 parts by weight of a photoinitiator (manufactured by IGM Resins B.V., trade name "Omnirad 651") were added and mixed. It was applied to the silicone release-treated surface of a polyester film (thickness 38 μm) subjected to silicone release treatment so that the dried thickness would be 30 μm, and dried at 125°C for 3 minutes to form an adhesive layer. The corona-treated surface of a 50-μm-thick PET subjected to corona treatment was bonded to the adhesive surface of the adhesive layer to transfer the adhesive layer, and an adhesive sheet was produced.

[0053] <Evaluation> The following evaluations were performed using the pressure-sensitive adhesive sheets obtained in the examples or comparative examples. The results are shown in Table 1. 1. Adhesive strength The obtained pressure-sensitive adhesive sheet was cut into a size of 20 mm in width and 80 mm in length, and was pressure-bonded to the mirror surface of a silicon mirror wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) with a hand roller reciprocated once in an atmosphere of 23°C, and left to stand at 23°C for 30 minutes. Then, the force required to peel off the pressure-sensitive adhesive sheet was measured under the conditions of 180° peeling and a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH, and was taken as the pre-UV adhesive strength. Also, a pressure-sensitive adhesive sheet was pressure-bonded to a silicon mirror wafer in the same manner and left to stand at 23°C for 30 minutes. Then, ultraviolet rays (UV) (integrated light amount: 500 mJ / cm 2 (converted to 365 nm)) were irradiated from the pressure-sensitive adhesive sheet surface side. Then, the force required to peel off the pressure-sensitive adhesive sheet was measured under the conditions of 180° peeling and a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH, and was taken as the post-UV adhesive strength.

[0054] 2. Back grinding property The pressure-sensitive adhesive sheets obtained in the examples or comparative examples were used as pressure-sensitive adhesive sheets for back grinding, and the back grinding process was performed under the following conditions. In the back grinding process, those that could be back ground without water intrusion or wafer cracking were rated as good, and those that could not were rated as bad. <Back grinding conditions> Grinder: Manufactured by DISCO, product name "Back Grinder DFG 6360" Wafer size: 8 inches Wafer thickness after back grinding: 100 μm

[0055]

Table 1

[0056] The abbreviations in Table 1 are the following materials, respectively. EP 4003S: Epoxy resin, manufactured by ADEKA, product name "Adekarezine EP4003S", epoxy equivalent: 470 (g / eq.) jER YX7103: Epoxy resin, manufactured by Mitsubishi Chemical Corporation, product name "jER YX7103", epoxy equivalent 430 (g / eq.) BFEM 50: Epoxy (meth)acrylate (mixture, 22% difunctional epoxy monomer, 50% compound having a monofunctional epoxy group and a monofunctional acryloyl group, 28% difunctional acrylic monomer), manufactured by CSM, product name "BFEM 50" BFEM 60: Epoxy (meth)acrylate (mixture, 16% difunctional epoxy monomer, 46% compound having a monofunctional epoxy group and a monofunctional acryloyl group, 38% difunctional acrylic monomer), manufactured by CSM, product name "BFEM 60" 4HBAGE: 4-Hydroxybutyl acrylate glycidyl ether, manufactured by Mitsubishi Chemical Corporation, 4-Hydroxybutyl acrylate glycidyl ether, epoxy equivalent: 200 (g / eq.) EX 121: 2-Ethylhexyl glycidyl ether, manufactured by Nagase ChemteX Corporation, product name: Denacol EX 121, epoxy equivalent: 187 (g / eq.) SI 80L: Thermal cationic polymerization initiator, manufactured by Sanshin Chemical Industry Co., Ltd., product name: Sun-Aid SI 80L 2EHA: 2-Ethylhexyl acrylate BA: Butyl acrylate BMA: Butyl methacrylate AN: Acrylonitrile AA: Acrylic acid E-118B: Emulsifier, manufactured by Kao Corporation, product name: Latemul E-118B WS 500: Oxazoline group-containing polymer, manufactured by Nippon Shokubai Co., Ltd., product name: Epocros WS-500 UW 9102: Polycarbonate diol, manufactured by Ube Industries, Ltd., product name: ETERNACOLL UW-9102 T / C: Polyfunctional epoxy resin, manufactured by Mitsubishi Gas Chemical Company, product name: TETRAD C DPHA: Dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., product name: KAYARAD DPHA Omnirad TPO-L: Photoinitiator, manufactured by iGM RESINS, product name: Omnirad TPO-L, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate Omnirad 500: Photoinitiator, manufactured by iGM RESINS, product name: Omnirad 500, a mixture of benzophenone (50%) and 1-hydroxycyclohexyl phenyl ketone (50%) Omnirad 651: Photoinitiator, manufactured by iGM RESINS, product name: Omnirad 651, 2,2-dimethoxy-2-phenylacetophenone

[0057] The pressure-sensitive adhesive sheet of the example of the present invention could be produced substantially without using a solvent. The pressure-sensitive adhesive sheet of the example of the present invention had a high adhesive force to the adherend before UV irradiation and could be easily peeled off without adhesive residue after UV irradiation.

Industrial Applicability

[0058] The pressure-sensitive adhesive forming material of the embodiment of the present invention can be suitably used for the production of a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet of the embodiment of the present invention can be suitably used for the processing step of a semiconductor wafer.

Explanation of Reference Numerals

[0059] 10 Substrate 20 Pressure-sensitive adhesive precursor layer 100 Pressure-sensitive adhesive sheet intermediate

Claims

1. An adhesive layer forming material comprising (A) a polyfunctional epoxy monomer, a thermal acid generator, and a photopolymerization initiator.

2. The adhesive layer forming material according to claim 1, wherein the epoxy equivalent of the polyfunctional epoxy monomer (A) is 250 g / eq or more.

3. The adhesive layer forming material according to claim 1, further comprising (B) a compound having an epoxy group and a (meth)acryloyl group.

4. The adhesive layer forming material according to claim 1, further comprising (C) a polyfunctional acrylic monomer.

5. The adhesive layer forming material according to claim 1, wherein the thermal acid generator is a sulfonium salt-based thermal acid generator.

6. An adhesive sheet intermediate comprising an adhesive precursor layer and a substrate, The adhesive sheet intermediate, wherein the adhesive precursor layer is formed using the adhesive layer forming material according to any one of claims 1 to 5.

7. Forming an adhesive precursor layer on a substrate using the adhesive layer forming material according to any one of claims 1 to 5 to form an adhesive sheet intermediate; A method for manufacturing an adhesive sheet, comprising heating the adhesive sheet intermediate.

8. An adhesive sheet comprising an adhesive layer containing a cationic polymer of an epoxy monomer having a (meth)acryloyl group in a side chain and a photopolymerization initiator, and a substrate.

9. The adhesive sheet according to claim 8, which is used for semiconductor processing.

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