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, exhibits excellent adhesive strength before ultraviolet irradiation and can be peeled off from an adherend without leaving an adhesive residue after ultraviolet irradiation.SOLUTION: There is provided an adhesive layer forming material which comprises a monomer component, a photoacid generator and a photopolymerization initiator whose absorbance at a wavelength of 365 nm of a 0.1 wt.% solution is 0.25 or less. 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 and fixing the surface of an adherend. 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, as chip miniaturization and thinning progress, 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). For an adhesive sheet used in the processing of a semiconductor wafer, an adhesive sheet whose adhesive force is reduced by ultraviolet irradiation has been proposed in order to be easily peeled off without adhesive residue during peeling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in order to reduce the environmental load, attempts have been made to reduce the amount of solvent used. As a polymerization method of a polymer capable of reducing the amount of solvent used, a method using a photopolymerization method is known. However, when this method is used, the adhesive force may not sufficiently decrease even when a photoinitiator is added to the obtained adhesive. In order to suppress adhesive residue during peeling, an adhesive sheet that exhibits excellent adhesive force before ultraviolet irradiation and can be peeled off from the adherend without adhesive residue after ultraviolet irradiation is required.

Means for Solving the Problems

[0005] 1. The pressure-sensitive adhesive layer forming material of the embodiment of the present invention includes a monomer component, a photoacid generator, and a photopolymerization initiator having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1 wt% solution. 2. In the pressure-sensitive adhesive layer forming material of 1 above, the monomer component may contain a polyfunctional epoxy monomer. 3. The pressure-sensitive adhesive layer forming material according to 1 or 2 above may further contain a (meth)acrylic monomer having an ethylenically unsaturated double bond. 4. In another aspect of the present invention, a pressure-sensitive adhesive sheet intermediate is provided. This pressure-sensitive adhesive sheet intermediate includes a pressure-sensitive adhesive precursor layer and a base material, and the pressure-sensitive adhesive precursor layer is formed using the pressure-sensitive adhesive layer forming material according to any one of 1 to 3 above. 5. In still another aspect of the present invention, a method for manufacturing a pressure-sensitive adhesive sheet is provided. This manufacturing method includes forming a pressure-sensitive adhesive precursor layer on a base material using the pressure-sensitive adhesive layer forming material according to any one of 1 to 3 above to form a pressure-sensitive adhesive sheet intermediate, and irradiating the pressure-sensitive adhesive sheet intermediate with ultraviolet light using a UV lamp having a peak top at a wavelength of 340 nm to 360 nm so that the integrated light amount is 10 mJ / cm 2 ~1000 mJ / cm 2 and including irradiating with ultraviolet light. 6. In still another aspect of the present invention, a pressure-sensitive adhesive sheet is provided. This pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer containing a photocationic polymer and a photopolymerization initiator having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1 wt% solution, and a base material. 7. In the pressure-sensitive adhesive sheet according to 6 above, the peak value P1 before ultraviolet irradiation at a wave number of 805 cm -1 ~815 cm -1 measured by Fourier transform infrared spectroscopy of the pressure-sensitive adhesive layer, and the peak value P2 at a wave number of 805 cm 2 after irradiating the pressure-sensitive adhesive layer with ultraviolet light having an integrated light amount of 2000 mJ / cm -1 ~815 cm -1 may satisfy the relationship of P2 / P1 ≦ 0.8. 8. The pressure-sensitive adhesive sheet according to 6 or 7 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 manufacture the pressure-sensitive adhesive sheet. 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 Drawings

[0007]

Figure 1

Embodiments 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 includes a monomer component; a photoacid generator; and a photopolymerization initiator (hereinafter, photopolymerization initiator (A)) having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1 wt% solution. 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 an adherend without using a diluent such as an organic solvent. Further, the pressure-sensitive adhesive layer forming material of the embodiment of the present invention has an integrated light amount of 10 mJ / cm using a UV lamp having a peak top at a wavelength of 340 nm to 360 nm later. 2 ~1000 mJ / cm 2 After ultraviolet irradiation so as to be, it is composed of a monomer component constituting the base polymer contained in the pressure-sensitive adhesive and an additive that may be contained in the pressure-sensitive adhesive, and substantially does not contain an organic solvent. According to the embodiment of the present invention, it is possible to reduce the amount of organic solvent used in the manufacturing process and provide a pressure-sensitive adhesive layer forming material capable of manufacturing a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet. After applying the pressure-sensitive adhesive precursor layer formed using this pressure-sensitive adhesive layer forming material to an adherend, the integrated light amount is 10 mJ / cm using a UV lamp having a peak top at a wavelength of 340 nm to 360 nm for the pressure-sensitive adhesive precursor layer. 2 ~1000 mJ / cm 2If ultraviolet rays are irradiated so as to generate acid from the photoacid generator in the pressure-sensitive adhesive precursor layer, the monomer component can be photo-cationically polymerized. As a result, a pressure-sensitive adhesive layer containing a photo-cationic polymer can be formed on the substrate, and a pressure-sensitive adhesive sheet can be obtained. Further, the photopolymerization initiator (A) contained in the pressure-sensitive adhesive layer forming material is contained in the formed pressure-sensitive adhesive layer. Therefore, the formed pressure-sensitive adhesive layer can function as an ultraviolet curable pressure-sensitive adhesive layer. Therefore, for example, the semiconductor pressure-sensitive adhesive sheet of the embodiment of the present invention can be suitably used in a semiconductor wafer processing step.

[0009] A-1. Monomer component As the monomer component, any suitable monomer is used. For example, epoxy monomers, (meth)acrylic monomers, epoxy acrylate monomers, vinyl monomers, etc. are mentioned. Epoxy monomers and (meth)acrylic monomers are preferred, and a combination of an epoxy monomer and a (meth)acrylic monomer is more preferably used. By using an epoxy monomer and a (meth)acrylic monomer, curing (dual cure) using two polymerization systems, cationic polymerization of the epoxy monomer and radical polymerization of the (meth)acrylic monomer, becomes possible, and it becomes possible to achieve both the production of a pressure-sensitive adhesive sheet using UV polymerization and the easy peeling of the pressure-sensitive adhesive sheet by UV curing after semiconductor wafer processing. The monomer component may be used alone or in combination of two or more.

[0010] A-1-1. Epoxy monomer As the epoxy monomer, any suitable compound having an epoxy group can be used. Preferably, an epoxy monomer having a functional group is used. For example, monofunctional epoxy monomers such as 4-tert-butylphenyl glycidyl ether, m,p-cresyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether; bisphenol compounds such as bisphenol A, bisphenol F, biphenol or their derivatives, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexanedimethanol, cyclohexanedietanol and other diols having an alicyclic structure or their derivatives, aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol or their derivatives and other epoxidized difunctional ones, trifunctional ones having a trihydroxyphenylmethane skeleton, an aminophenol skeleton, polyfunctional ones obtained by epoxidizing phenol novolak resin, cresol novolak resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, etc. Preferably, a polyfunctional epoxy monomer is used. As the epoxy monomer, more preferably a polyfunctional epoxy monomer is used, and even more preferably bisphenol compounds such as bisphenol A, bisphenol F, biphenol or their derivatives, etc. are used. With these polyfunctional epoxy monomers, a crosslinking reaction occurs during cationic polymerization by the epoxy group, and an adhesive tape having an adhesive layer with higher cohesive force and excellent adhesive properties can be obtained. The epoxy monomer may be used alone or in combination of two or more.

[0011] When using a polyfunctional epoxy monomer, the epoxy equivalent weight of the polyfunctional epoxy monomer is preferably 100 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 weight of the polyfunctional epoxy monomer is, for example, 1500 g / eq or less. If the epoxy equivalent weight of the polyfunctional epoxy monomer is within the above range, the distance between crosslinking points of the polymer obtained by cationic polymerization can be increased. As a result, an adhesive having more excellent adhesiveness can be obtained.

[0012] The polyfunctional epoxy monomer is preferably 50% by weight to 95% by weight, more preferably 60% by weight to 95% by weight, and still more preferably 60% by weight to 90% by weight, based on 100% by weight of the total monomer components.

[0013] In one embodiment, it is preferable to use in combination an epoxy monomer having an epoxy equivalent weight of 100 g / eq to 500 g / eq (hereinafter also referred to as epoxy monomer (A)) and an epoxy monomer having an epoxy equivalent weight of 300 g / eq to 1500 g / eq (hereinafter also referred to as epoxy monomer (B)) as the polyfunctional epoxy monomer. Epoxy monomer (A) and (B) may each be used alone or in combination of two or more.

[0014] The epoxy equivalent weight of epoxy monomer (A) is preferably 100 g / eq to 400 g / eq, more preferably 200 g / eq to 400 g / eq. Epoxy monomer (A) is preferably 50% by weight or less, more preferably 40% by weight or less, based on 100% by weight of the total monomer components having an epoxy group contained in the monomer composition (for example, the epoxy monomers exemplified above). The content ratio of epoxy monomer (A) is, for example, 5% by weight or more.

[0015] The epoxy equivalent of the epoxy monomer (B) is preferably 300 g / eq to 1500 g / eq, more preferably 300 g / eq to 1000 g / eq. The epoxy monomer (B) is preferably 50% by weight or more, more preferably 60% by weight or more, out of 100% by weight in total of the monomer components having an epoxy group contained in the monomer composition (for example, the epoxy monomers exemplified above). The content ratio of the epoxy monomer (B) is, for example, 95% by weight or less. If the content ratio of the epoxy monomer (B) is within the above range, the distance between crosslinking points of the polymer obtained by cationic polymerization becomes appropriate, and an adhesive layer forming material having more excellent adhesive properties can be obtained.

[0016] A-1-2. Other monomers The adhesive layer forming material of the embodiment of the present invention may further contain any suitable monomer component. For example, any suitable monomer having one epoxy group is used. For example, an epoxy diluent containing a monofunctional epoxy, and a compound having an epoxy group and a (meth)acryloyl group can be mentioned. Specific examples of the compound having an epoxy group and a (meth)acryloyl group include 4-hydroxybutyl acrylate glycidyl ether, bisphenol A epoxy partial acrylate, bisphenol F epoxy partial acrylate, and the like. These monomers may be used alone or in combination of two or more. Other monomers are used in any suitable content ratio.

[0017] A-2. (Meth)acrylic monomer having an ethylenically unsaturated double bond The pressure-sensitive adhesive layer forming material preferably further contains a (meth)acrylic monomer having an ethylenically unsaturated double bond. If it further contains a (meth)acrylic monomer having an ethylenically unsaturated double bond, after irradiating the formed pressure-sensitive adhesive layer with ultraviolet rays, the pressure-sensitive adhesive sheet can be more favorably peeled off. Examples of the (meth)acrylic monomer having an ethylenically unsaturated double bond include alkyl (meth)acrylates such as lauryl (meth)acrylate and stearyl (meth)acrylate (alkyl having 12 to 18 carbon atoms), (meth)acrylate of an alkylphenol ethylene oxide adduct and propylene oxide adduct such as benzyl (meth)acrylate, butylphenol, octylphenol, nonylphenol or dodecylphenol, (meth)acrylates having a ring structure such as isobornyl (meth)acrylate, tricyclodecane monomethylol (meth)acrylate, cyclohexyl (meth)acrylate, and adamantyl (meth)acrylate. Further, a polyfunctional (meth)acrylic monomer such as 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, or dipentaerythritol hexaacrylate may be used. Preferably, a (meth)acrylate having a glass transition temperature (Tg) of 0°C or higher and 250°C or lower is used, more preferably a (meth)acrylate having a glass transition temperature (Tg) of 20°C or higher and 250°C or lower is used, and even more preferably a (meth)acrylate having a glass transition temperature (Tg) of 50°C or higher and 250°C or lower is used. Specifically, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and adamantyl (meth)acrylate are preferably used. By using these compounds having an ethylenically unsaturated double bond, a pressure-sensitive adhesive layer forming material capable of forming a pressure-sensitive adhesive layer that can be more easily peeled off after ultraviolet irradiation can be obtained. Only one kind of the (meth)acrylic monomer having an ethylenically unsaturated double bond may be used, or two or more kinds may be used in combination. In this specification, the glass transition temperature of the (meth)acrylate refers to the glass transition temperature of a homopolymer obtained by homopolymerizing the (meth)acrylic monomer.

[0018] The content of the (meth)acrylic monomer having an ethylenically unsaturated double bond is preferably 5% by weight to 50% by weight, more preferably 10% by weight to 50% by weight, and still more preferably 20% by weight to 50% by weight, out of 100% by weight of the total monomer components. When the content of the (meth)acrylic monomer having an ethylenically unsaturated double bond is within the above range, a pressure-sensitive adhesive sheet that can be peeled off from the adherend without adhesive residue can be obtained after ultraviolet irradiation.

[0019] A-3. Photoacid generator The photoacid generator may be any compound that generates an acid when irradiated with radiation such as visible light, ultraviolet light, γ-rays, or electron beams, and any suitable compound can be used. For example, iodonium salt-based photoacid generators, sulfonium salt-based photoacid generators, pyridinium salt-based photoacid generators, trihalomethyl-S-triazine-based photoacid generators, etc. may be mentioned. Preferably, a sulfonium salt-based photoacid generator is used. By using these photoacid generators, polymerization of the epoxy resin can be favorably carried out on the substrate by ultraviolet irradiation. Only one kind of photoacid generator may be used, or two or more kinds may be used in combination.

[0020] The photoacid generator is preferably a compound that generates an acid at a wavelength of 300 nm to 400 nm, more preferably a compound that generates an acid at a wavelength of 320 nm to 380 nm, and still more preferably a compound that generates an acid at a wavelength of 320 nm to 350 nm. With a photoacid generator that generates an acid at the above wavelengths, cationic polymerization of the base polymer can be favorably carried out on the adherend or the substrate.

[0021] Commercially available products may be used as the photoacid generator. For example, CPI series such as the product named "CPI-101A" manufactured by San-Apro Ltd. may be mentioned.

[0022] The photoacid generator can be used in any suitable content. The content of the photoacid generator is preferably 0.5 to 20 parts by weight, more preferably 1 to 15 parts by weight, and still more preferably 1.5 to 10 parts by weight with respect to 100 parts by weight in total of the monomer components. If the content of the photoacid generator is within the above range, the polymerization of the epoxy resin can be favorably carried out on the adherend or the substrate.

[0023] A photopolymerization initiator (photopolymerization initiator (A)) having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1% by weight solution As the photopolymerization initiator having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1% by weight solution, any suitable compound can be used. The absorbance of the 0.1% by weight solution of the photopolymerization initiator at a wavelength of 365 nm is 0.25 or less, more preferably 0.20 or less, and still more preferably 0.10 or less. The absorbance of the 0.1% by weight solution at a wavelength of 365 nm is, for example, 0.001 or more. If the absorbance of the photopolymerization initiator (A) is within the above range, an adhesive layer forming material capable of forming an adhesive layer (that is, an ultraviolet curable adhesive layer) that can be peeled off from the adherend without residue after ultraviolet irradiation can be obtained even when used in combination with a base polymer that is a photocationic polymer. The absorbance of the photopolymerization initiator can be measured with a spectrophotometer using a solution prepared by dissolving the photopolymerization initiator in a solvent (for example, ethyl acetate) to a concentration of 0.1% by weight.

[0024] As the photopolymerization initiator (A), for example, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (absorbance: 0.01), 1-hydroxycyclohexyl phenyl ketone (absorbance: 0.11), etc. can be used. Preferably, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone can be used. With these photopolymerization initiators, even when used in combination with a base polymer that is a photocationic polymer, an adhesive layer forming material capable of forming an adhesive layer (i.e., an ultraviolet curable adhesive layer) that can be peeled off from the adherend without adhesive residue after ultraviolet irradiation can be obtained. The photopolymerization initiator (A) may be used alone or in combination of two or more.

[0025] As the photopolymerization initiator (A), commercially available products may be used. For example, products named "Omnirad 2959", "Omnirad 184", etc. manufactured by IGM Resins can be mentioned.

[0026] The photopolymerization initiator (A) can be used in any appropriate amount. The content of the photopolymerization initiator 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 photopolymerization initiator is less than 0.5 parts by weight, there is a risk of insufficient curing during ultraviolet irradiation.

[0027] A-5. Additives The adhesive layer forming material may further use any appropriate additives as necessary. Examples of the additives include crosslinking agents, catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, anti-aging agents, conductive materials, ultraviolet absorbers, light stabilizers, peel adjustment agents, softeners, flame retardants, etc. The additives are used in any appropriate amount according to the purpose.

[0028] A-6. Preparation method The pressure-sensitive adhesive layer forming material can be prepared by any suitable method. For example, it can be prepared by mixing a monomer component, a photoacid generator, a photopolymerization initiator (A), a (meth)acrylic monomer having any ethylenically unsaturated double bond, 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 layer precursor layer 20. The pressure-sensitive adhesive precursor layer 20 is formed using the above-described pressure-sensitive adhesive layer forming material. 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, a pressure-sensitive adhesive sheet intermediate capable of forming a pressure-sensitive adhesive layer (i.e., an ultraviolet curable pressure-sensitive adhesive layer) that can be peeled off from the adherend without residue after ultraviolet irradiation can be obtained even when used in combination with a base polymer that is a photocationic polymer.

[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 polyolefin resin or 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 still 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 the method 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, and screen printing can be adopted.

[0037] C. Method for manufacturing an adhesive sheet The method for manufacturing an adhesive sheet according to an embodiment of the present invention includes forming a pressure-sensitive adhesive precursor layer using a pressure-sensitive adhesive layer forming material to form an adhesive sheet intermediate, and using a UV lamp having a peak top at a wavelength of 340 nm to 360 nm to obtain an integrated light amount of 10 mJ / cm 2 ~1000 mJ / cm 2 and irradiating with ultraviolet light so as to be. 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 adhesive sheet intermediate including this pressure-sensitive adhesive precursor layer is irradiated with ultraviolet light so that the integrated light amount is 10 mJ / cm 2 ~1000 mJ / cm 2 a photocationic polymer serving as a base polymer can be formed in the pressure-sensitive adhesive precursor layer. More specifically, an acid is generated from a photoacid generator by irradiation with active energy rays, and a monomer component (for example, an epoxy monomer) contained in the pressure-sensitive adhesive precursor layer can be cationically polymerized. As a result, a pressure-sensitive adhesive layer (ultraviolet curable pressure-sensitive adhesive layer) including a photocationic polymer as a base polymer and a photopolymerization initiator having an absorbance at a wavelength of 365 nm of 0.25 or less in a 0.1 wt% solution can be formed on the substrate. This pressure-sensitive adhesive layer has excellent adhesion to the adherend before ultraviolet irradiation and can be peeled from the adherend without residue after ultraviolet irradiation. Therefore, for example, an adhesive sheet suitable for semiconductor wafer processing can be obtained.

[0038] C-1. Preparation of an adhesive sheet intermediate As described in item B above, an adhesive precursor layer is formed on a substrate using the above-described adhesive layer forming material. As described above, the adhesive layer forming material has a low viscosity (for example, 20 Pa·s or less at 25°C), and an adhesive precursor layer can be formed on a substrate without using an organic solvent. Further, the adhesive precursor layer does not have an adhesive force capable of exhibiting the function as an adhesive. Specifically, the adhesive precursor layer may have an adhesive force in a 180° peel test measured at a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH that is less than 0.1 N / 20 mm.

[0039] C-2. UV Irradiation Step The adhesive sheet intermediate having a substrate and an adhesive precursor layer is subjected to a UV irradiation step. The UV irradiation step is performed by irradiating ultraviolet rays using a UV lamp having a peak top at a wavelength of 340 nm to a wavelength of 360 nm so that the integrated light amount is 10 mJ / cm 2 ~1000 mJ / cm 2 As a result of this UV irradiation step, an acid is generated from the photoacid generator, and an adhesive layer containing a photocationic polymer can be formed on the substrate. Further, in this UV irradiation step, the photoinitiator (A) does not participate in the polymerization reaction and can remain unreacted in the formed adhesive layer. As a result, an adhesive sheet having a UV-curable adhesive layer can be obtained.

[0040] As the UV lamp having a peak top at a wavelength of 340 nm to a wavelength of 360 nm, any suitable device can be used. For example, a black light, an LED lamp, etc. can be mentioned. Preferably, it is a black light. By using these as the UV lamp, in this UV irradiation step, the photoinitiator (A) does not participate in the polymerization reaction and can remain unreacted in the formed adhesive layer. As a result, an adhesive sheet having a UV-curable adhesive layer can be obtained.

[0041] The integrated light amount in the UV irradiation step is 10 mJ / cm 2 ~1000 mJ / cm 2 and preferably 30 mJ / cm 2 ~500 mJ / cm 2 and more preferably 50 mJ / cm 2~300 mJ / cm 2 If the integrated light quantity is within the above range, the polymerization reaction of the monomer component proceeds, and an adhesive layer having an adhesive force that can function as an adhesive layer can be formed.

[0042] C-3. Heating step The adhesive sheet intermediate that has been subjected to the ultraviolet irradiation step may be further subjected to a heating step. If it is further subjected to the heating step, an ultraviolet curable adhesive layer excellent in curability after ultraviolet irradiation can be formed. The heating can be performed by any suitable method.

[0043] The heating temperature can be set to any appropriate value. The heating temperature is preferably 30°C to 100°C, more preferably 35°C to 95°C, and even more preferably 40°C to 90°C. Also, the heating time is preferably 10 seconds to 300 seconds, more preferably 30 seconds to 180 seconds.

[0044] As the heating means, any appropriate device can be used. For example, an oven or the like can be mentioned.

[0045] D. Adhesive sheet The adhesive sheet of the embodiment of the present invention contains a photocationic polymer and a photoinitiator having an absorbance at a wavelength of 365 nm of 0.1 wt% solution of 0.25 or less. The adhesive sheet of the embodiment of the present invention can be manufactured using the above-described adhesive forming material and an adhesive sheet intermediate in which an adhesive precursor layer is formed. The adhesive sheet of the embodiment of the present invention can have excellent adhesion to an adherend before ultraviolet irradiation. Also, after ultraviolet irradiation, the photocationic polymer and the photoinitiator (A) react and the adhesive force decreases, and it can be peeled off from the adherend without adhesive residue. Also, as described above, the adhesive layer forming material substantially does not contain an organic solvent. Therefore, problems that may occur due to the adhesive layer containing an organic solvent (for example, deterioration of the adherend due to the solvent volatilized from the adhesive layer) can also be suppressed. Furthermore, an abnormal odor derived from the organic solvent and the influence on the human body by inhaling the volatilized organic solvent can also be suppressed.

[0046] The adhesive layer has a relationship of P2 / P1 ≦ 0.8 between the peak value P1 before ultraviolet irradiation at a wave number of 805 cm -1 ~815 cm -1 measured by Fourier transform infrared spectroscopy and the peak value P2 at a wave number of 805 cm 2 ~815 cm -1 after irradiating the adhesive layer with ultraviolet light at an integrated light amount of 2000 mJ / cm -1 It is preferably satisfied. If the adhesive layer satisfies such a relationship, it can be understood that the (meth)acrylate groups in the adhesive layer have reacted with the photoinitiator. If the (meth)acrylate groups in the adhesive layer have reacted, the elastic modulus of the adhesive layer increases, and the peelability of the adhesive force becomes possible. P2 / P1 is preferably 0.7 or less, more preferably 0.6 or less. Also, P2 / P1 is preferably 0.1 or more. In this specification, the peak value P1 refers to the value measured by the following method. Cut the adhesive sheet into a sample with a width of 20 mm and a length of 20 mm. Using a diamond prism, measurement is performed using a Fourier transform infrared spectrometer (for example, manufactured by Thermo Fisher Scientific, product name: NICOLET iS10), and the value of the largest peak top at a wave number of 805 cm -1 ~815 cm -1 is taken as P1. The peak P2 refers to the value measured by the following method. Irradiate the sample with ultraviolet light so that the integrated light amount becomes 2000 mJ / cm 2 , and leave it for 30 minutes. Then, perform the measurement in the same manner as P1, and the value of the largest peak top at a wave number of 805 cm -1 ~815 cm -1 is taken as P2.

[0047] The adhesive sheet preferably has an adhesive force to a polypropylene plate of the adhesive sheet before ultraviolet irradiation of 0.5 N / 20 mm or more, more preferably 0.6 N / 20 mm or more, and still more preferably 0.8 N / 20 mm or more. If the adhesive force to the polypropylene plate before ultraviolet irradiation is within the above range, it has excellent adhesion to the adherend. Also, the adhesive force to the polypropylene plate is, for example, 1.5 N / 20 mm or less. In this specification, the adhesive force to the polypropylene plate refers to the adhesive force measured by the following method. Cut the adhesive sheet into a width of 20 mm and a length of 80 mm, and press-bond it to the polypropylene plate with a hand roller reciprocated once in an atmosphere of 23°C, and leave it at 23°C for 30 minutes. Then, a 180° peel test is performed at a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH to measure the force required to peel off the adhesive sheet.

[0048] The adhesive sheet has an integrated light quantity of 2000 mJ / cm 2 After ultraviolet irradiation so that the adhesive force of the adhesive sheet to the polypropylene plate is preferably 2 N / 20 mm or less, more preferably 1.5 N / 20 mm or less, and still more preferably 1 N / 20 mm or less. If the adhesive force to the polypropylene plate 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 of the adhesive sheet to the polypropylene plate after ultraviolet irradiation so that the integrated light quantity is 2000 mJ / cm 2 refers to the value measured by the following method. Cut the adhesive sheet into a width of 20 mm and a length of 80 mm, and press-bond it to the polypropylene plate with a hand roller reciprocated once in an atmosphere of 23°C, and leave it at 23°C for 30 minutes. Then, irradiate ultraviolet rays (UV) from the adhesive sheet surface side so that the integrated light quantity is 2000 mJ / cm 2 (converted to 365 nm). Next, a 180° peel test is performed under the conditions of a tensile speed of 300 mm / min in an atmosphere of 23°C and 50% RH to measure the force required to peel off the adhesive sheet.

[0049] 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.

[0050] 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.

[0051] 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 exhibits excellent adhesive force before ultraviolet irradiation and can be peeled off from the adherend without adhesive residue after ultraviolet irradiation. Therefore, it can be suitably used in the manufacturing process of the semiconductor wafer of the embodiment of the present invention. For example, it can be used as a pressure-sensitive adhesive sheet for semiconductor wafer processing such as dicing tape and back grinding tape.

Examples

[0052] 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, unless otherwise specified, "parts" and "%" are based on weight.

[0053] [Example 1] (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) Preparation of the pressure-sensitive adhesive sheet intermediate A 50-μm-thick polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., trade name "Lumirror #50 S-105") having one surface corona-treated was coated with the pressure-sensitive adhesive layer forming material to form a 30-μm-thick pressure-sensitive adhesive precursor layer. (3) Preparation of the pressure-sensitive adhesive sheet Next, onto the pressure-sensitive adhesive precursor layer, ultraviolet light with an illuminance of 5 mW / cm 2 was irradiated for 20 seconds using a black light lamp (manufactured by Toshiba Corporation, with a maximum sensitivity at approximately 350 nm). Next, after leaving it in a dryer set at 60°C for 2 minutes, it was taken out of the dryer to obtain a pressure-sensitive adhesive sheet. The maximum sensitivity of the black light was measured using a product named "UVR-T1" manufactured by Topcon Corporation.

[0054] (Comparative Example 1) 40 parts by weight of 2-ethylhexyl acrylate (2EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), 40 parts by weight of isostearyl acrylate (ISTA), 0.05 part by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184"), and 0.05 part by weight of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) were charged into a four-necked flask. Next, the mixture was exposed to ultraviolet light under a nitrogen atmosphere and partially photopolymerized to obtain a partial polymer (acrylic polymer syrup 1) with a polymerization rate of approximately 10% by weight. To the obtained acrylic syrup 1, 60 parts by weight of isobornyl acrylate (IBXA), and 3 parts by weight of a mixture of 1.5 parts by weight of a photopolymerization initiator (manufactured by IGM Resins B.V., trade name "Omnirad 184") and 1.5 parts by weight of a photopolymerization initiator (manufactured by IGM Resins B.V., trade name "Omnirad 819") (absorbance at a wavelength of 365 nm of a 0.1% by weight solution (0.1% by weight solution of the mixture): 0.27) were added to obtain a pressure-sensitive adhesive layer-forming composition. The pressure-sensitive adhesive layer-forming material was applied onto a 50-μm-thick polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., trade name "Lumirror #50 S-105") having one surface corona-treated to form a 30-μm-thick pressure-sensitive adhesive precursor layer. Next, the release-treated surface of a 38-μm-thick release liner (manufactured by Mitsubishi Chemical Corporation, trade name "Diafoil MRF38") and the pressure-sensitive adhesive precursor layer were bonded together with a hand roller to block the pressure-sensitive adhesive precursor layer from oxygen and obtain a pressure-sensitive adhesive sheet intermediate. Next, onto the pressure-sensitive adhesive sheet intermediate, ultraviolet light with an illuminance of 40 mW / cm 2The obtained adhesive sheet was irradiated with light for 50 seconds.

[0055] (Comparative Example 2) Instead of irradiating with light of 40 mW / cm using a 365LED (manufactured by HOYA Candeo Optronics) for 50 seconds, a high-pressure mercury lamp (manufactured by Nitto Seiki Co., Ltd.) was used to irradiate with light of 40 mW / cm 2 for 50 seconds (integrated light amount: 2000 mJ / cm 2 ). An adhesive sheet was obtained in the same manner as in Comparative Example 1 except for this. 2 )

[0056] (Comparative Example 3) An adhesive sheet was obtained in the same manner as in Example 1 except that the irradiation time of the black light was set to 5 minutes.

[0057] (Evaluation) Using the adhesive sheets obtained in the examples or comparative examples, the following evaluations were conducted. The results are shown in Table 1. 1. Adhesive force The obtained adhesive sheet was cut into a size of 20 mm in width and 80 mm in length, and was pressure-bonded to a polypropylene plate (manufactured by Hitachi Chemical Co., Ltd.) with a hand roller once in an atmosphere of 23°C, and left to stand for 30 minutes at 23°C. Then, the force required to peel the 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 force. Also, in the same manner, the adhesive sheet was pressure-bonded to the polypropylene plate and left to stand for 30 minutes at 23°C. Next, ultraviolet rays (UV) (integrated light amount: 2000 mJ / cm 2 (converted to 365 nm)) were irradiated from the adhesive sheet surface side. Then, the force required to peel the 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 force.

[0058] 2. Peak top value The pressure-sensitive adhesive sheet was cut into samples with a width of 20 mm and a length of 20 mm. Using a diamond prism, measurements were carried out with a Fourier transform infrared spectrophotometer (manufactured by Thermo Fisher Scientific, product name: NICOLET iS10) in the wavenumber range of 805 cm -1 ~815 cm -1 and the value of the peak top with the largest magnitude was designated as P1. Separately, the sample was irradiated with ultraviolet light so that the integrated light quantity became 2000 mJ / cm 2 and left for 30 minutes. Thereafter, measurements were carried out in the same manner as for P1 in the wavenumber range of 805 cm -1 ~815 cm -1 and the value of the peak top with the largest magnitude was designated as P2. P2 / P1 was calculated from the values of P1 and P2.

[0059]

Table 1

[0060] The abbreviations in Table 1 are the following materials, respectively. EP 4003L: Epoxy resin, manufactured by ADEKA Corporation, product name "Adekarezine EP4003L", epoxy equivalent: 470 (g / eq.) EP 4010L: Epoxy resin, manufactured by ADEKA Corporation, product name "Adekarezine EP4010L", epoxy equivalent: 310 (g / eq.) IBXA: Isobornyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "IBXA" CPI-101A: Photoacid generator, manufactured by San-Apro Ltd., product name "CPI-101A" Omnirad 2959: Photoinitiator, manufactured by iGM RESINS GmbH, product name "Omnirad 2959" (absorbance at a wavelength of 365 nm in a 0.1 wt% solution: 0.01) Omnirad 184: Acid generator, manufactured by iGM RESINS GmbH, product name "Omnirad 184" (absorbance at a wavelength of 365 nm in a 0.1 wt% solution: 0.11) Omnirad 819: Photoinitiator, manufactured by iGM RESINS GmbH, product name "Omnirad 819" (absorbance at a wavelength of 365 nm in a 0.1 wt% solution: 0.34) Omnirad 651: A photoinitiator, manufactured by iGM RESINS, trade name "Omnirad 651" (absorbance at a wavelength of 365 nm in a 0.1 wt% solution is 0.44)

[0061] 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

[0062] 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 in the processing step of a semiconductor wafer.

Explanation of Reference Numerals

[0063] 10 Substrate 20 Pressure-sensitive adhesive precursor layer 100 Pressure-sensitive adhesive sheet intermediate

Claims

1. An adhesive layer forming material comprising a monomer component, a photoacid generator, and a photopolymerization initiator having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1 wt% solution.

2. The adhesive layer forming material according to claim 1, wherein the monomer component contains a polyfunctional epoxy monomer.

3. The adhesive layer forming material according to claim 1, further comprising a (meth)acrylic monomer having an ethylenically unsaturated double bond.

4. An adhesive sheet intermediate comprising an adhesive precursor layer and a substrate, wherein the adhesive precursor layer is formed using the adhesive layer forming material according to any one of claims 1 to 3.

5. Forming an adhesive precursor layer on a substrate using the adhesive layer forming material according to any one of claims 1 to 3 to form an adhesive sheet intermediate, and irradiating the adhesive sheet intermediate with ultraviolet light using a UV lamp having a peak top at a wavelength of 340 nm to 360 nm so that the integrated light amount is 10 mJ / cm ２ to 1000 mJ / cm ２ A method for manufacturing an adhesive sheet comprising:

6. An adhesive sheet comprising an adhesive layer containing a photocationic polymer and a photopolymerization initiator having an absorbance of 0.25 or less at a wavelength of 365 nm in a 0.1 wt% solution, and a substrate.

7. The peak value P before ultraviolet irradiation at a wave number of 805 cm －１ to 815 cm －１ measured by Fourier transform infrared spectroscopy of the adhesive layer, １ and the peak value P at a wave number of 805 cm ２ after irradiating the adhesive layer with ultraviolet light having an integrated light amount of 2000 mJ / cm －１ to 815 cm －１ satisfy P ２ / P ２ / P １The pressure-sensitive adhesive sheet according to claim 6, satisfying the relationship of ≦0.

8.

8. The pressure-sensitive adhesive sheet according to claim 6, which is used for semiconductor processing.

Images