Backgrind tape

Abstract

To provide a backgrinding tape which has an excellent unevenness-embedding property and an excellent pressure-sensitive adhesive property, and can prevent an adhesive residue on an adherend at the time of its peeling.SOLUTION: A backgrinding tape includes a base material and a UV-curable pressure-sensitive adhesive layer. When not subjected to UV irradiation, the UV-curable pressure-sensitive adhesive layer has a shear storage modulus of elasticity G'1 at 25°C of 0.175 MPa or more and a pressure-sensitive adhesive strength to silicon of 1 N / 20 mm or more. When subjected to UV irradiation, the UV-curable pressure-sensitive adhesive layer of the backgrinding tape has a tensile storage modulus of elasticity E'1 at 25°C of 300 MPa or less and a pressure-sensitive adhesive strength to silicon of 0.15 N / 20 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to backgrind tape. [Background technology]

[0002] Semiconductor wafers are used in a variety of applications, including personal computers, smartphones, and automobiles. In the semiconductor wafer processing process, adhesive tape is used to protect the surface during processing. In recent years, the miniaturization and increased functionality of large-scale integrated circuits (LSIs) have led to a more complex wafer surface structure. Specifically, this includes the increased complexity of the three-dimensional structure of the wafer surface due to solder bumps and other factors. Therefore, adhesive tape used in semiconductor processing requires the ability to fill in surface irregularities and strong adhesion. Adhesive tape used in the semiconductor wafer backgrinding process is required to properly hold the semiconductor wafer during the backgrinding process and to be easily peeled off afterward. Since the thickness of a semiconductor wafer becomes significantly thinner after backgrinding, the backgrinding tape must be able to be peeled off without leaving adhesive residue or damaging the semiconductor wafer.

[0003] In recent years, with the miniaturization and thinning of various products, semiconductor wafers have also been thinned. When using thin wafers, if the adhesive strength of the adhesive tape is too high, the wafer may be damaged when the tape is removed. Therefore, adhesive tapes using UV-curable adhesives have been proposed to prevent adhesive residue on the substrate and wafer damage during removal (for example, Patent Documents 1 and 2). However, even when using UV-curable adhesives, the adhesive strength may not decrease sufficiently, leading to problems such as adhesive residue on the substrate and wafer damage during removal. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-017758 [Patent Document 2] Japanese Patent Publication No. 2013-213075 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention was made to solve the above-mentioned conventional problems, and aims to provide a backgrind tape that has excellent ability to fill in uneven surfaces and adhesive properties, and that can prevent adhesive residue from being left on the adherend when peeled off. [Means for solving the problem]

[0006] 1. The backgrind tape according to an embodiment of the present invention comprises a base material and an ultraviolet-curable adhesive layer. The ultraviolet-curable adhesive layer not irradiated with ultraviolet light has a 25°C shear storage modulus G'1 of 0.175 MPa or more and an adhesive strength to silicone of 1 N / 20 mm or more, while the ultraviolet-irradiated ultraviolet-curable adhesive layer of the backgrind tape has a 25°C tensile storage modulus E'1 of 300 MPa or less and an adhesive strength to silicone of 0.15 N / 20 mm or less. 2. The backgrind tape described in 1. above may be used by being attached to an object having an uneven surface. 3. The backgrind tape described in 2. above may have a step difference of 10 μm to 200 μm. 4. The back glide tape described in 2. or 3. above may have the above-mentioned irregularities as protruding electrodes. 5. The backgrind tape described in any of 1 to 4 above further comprises an intermediate layer, which may be disposed between the substrate and the ultraviolet-curable adhesive layer. 6. In the backgrind tape described in item 5 above, the thickness of the intermediate layer may be 10 μm to 300 μm. 7. In the backgrind tape described in item 5 or 6 above, the shear storage modulus G'3 of the intermediate layer at 25°C may be 0.3 MPa to 10 MPa, and the shear storage modulus G'4 of the intermediate layer at 80°C may be 0.01 MPa to 0.5 MPa. 8. In the backgrind tape described in any of items 1 to 7 above, the thickness of the ultraviolet-curable adhesive layer may be 1 μm to 100 μm. 9. In the backgrind tape described in any of 1 to 8 above, the 80°C shear storage modulus G'2 of the UV-curable adhesive layer of the backgrind tape that has not been irradiated with UV light may be 0.01 MPa to 1 MPa. 10. In the backgrind tape described in any of items 1 to 9 above, the 60°C tensile storage modulus E'2 of the UV-curable adhesive layer irradiated with ultraviolet light may be 30 MPa or less. 11. In the backgrind tape described in any of 1 to 10 above, the UV-curable adhesive layer is a layer formed from an adhesive composition comprising a base polymer and a photopolymerization initiator, wherein the base polymer may be a polymer obtained by polymerizing a monomer composition comprising a polymer having a hydroxyl group and a monomer represented by formula (1): [ka] (In the formula, n is an integer greater than or equal to 1). [Effects of the Invention]

[0007] According to embodiments of the present invention, a backgrind tape can be provided that has excellent ability to fill in uneven surfaces and adhesive properties, and that can prevent adhesive residue from being left on the adherend when peeled off. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of a backgrind tape according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] A. Overall structure of the backgrind tape The backgrind tape according to an embodiment of the present invention comprises a substrate and an ultraviolet-curable adhesive layer. This backgrind tape has a 25°C shear storage modulus G'1 of 0.175 MPa or higher for the ultraviolet-curable adhesive layer before ultraviolet irradiation, and an adhesive strength to silicon of 1 N / 20 mm or higher. Furthermore, this backgrind tape has a 25°C tensile storage modulus E'1 of 300 MPa or lower for the ultraviolet-curable adhesive layer after ultraviolet irradiation, and an adhesive strength to silicon of 0.15 N / 20 mm or lower. Thus, the backgrind tape according to an embodiment of the present invention can exhibit excellent surface-filling properties and adhesive strength in the non-ultraviolet irradiation stage. Furthermore, the backgrind tape according to an embodiment of the present invention can exhibit excellent easy peelability after ultraviolet irradiation. Therefore, it can be suitably used as a backgrind tape, which is an adhesive tape that protects silicon wafers in the backgrinding process. In this specification, adhesive strength to silicon refers to the adhesive strength to a silicon mirror wafer measured using a backgrind tape on which an ultraviolet-curable adhesive layer has been formed. In this specification, a backgrind tape irradiated with ultraviolet light is defined as a tape with an integrated light intensity of 700 mJ / cm². 2 This refers to back-grind tape in which the UV-curable adhesive layer has been irradiated with ultraviolet light to achieve the desired result.

[0010] The shear storage modulus G'1 of the ultraviolet-curable adhesive layer without ultraviolet irradiation at 25°C is 0.175 MPa or more, preferably 0.2 MPa or more, and more preferably 0.23 MPa or more. When the shear storage modulus G'1 at 25°C is within the above range, excellent embedding property of unevenness can be exhibited even when the adherend has unevenness. The shear storage modulus G'1 of the ultraviolet-curable adhesive layer at 25°C is, for example, 0.80 MPa or less. In this specification, the shear storage modulus G'1 at 25°C refers to the value measured by a dynamic viscoelasticity measuring device using a sample in which an adhesive layer with a thickness of 1 mm is formed using an adhesive composition. In this specification, non-ultraviolet irradiation means a state where the ultraviolet-curable adhesive layer is not irradiated with ultraviolet rays.

[0011] The adhesion to silicon of the ultraviolet-curable adhesive layer without ultraviolet irradiation is 1 N / 20 mm or more, preferably 3 N / 20 mm or more, and more preferably 5 N / 20 mm or more. The adhesion to silicon of the ultraviolet-curable adhesive layer is, for example, 15 N / 20 mm or less. When the adhesion to silicon is within the above range, excellent adhesiveness to an adherend, for example, a silicon wafer, can be exhibited.

[0012] The tensile storage modulus E'1 of the ultraviolet-curable adhesive layer of the back grind tape irradiated with ultraviolet rays at 25°C is 300 MPa or less, preferably 200 MPa or less, and more preferably 150 MPa or less. The tensile storage modulus E'1 of the ultraviolet-curable adhesive layer of the back grind tape irradiated with ultraviolet rays at 25°C is, for example, 50 MPa or more. When the tensile storage modulus E'1 after ultraviolet irradiation is within the above range, excellent peelability after ultraviolet irradiation can be exhibited, and adhesive residue on the adherend can be prevented.

[0013] The adhesion of the ultraviolet-cured adhesive layer to silicon after ultraviolet irradiation is 0.15 N / 20 mm or less, preferably 0.10 N / 20 mm or less, and more preferably 0.08 N / 20 mm or less. The adhesion of the ultraviolet-irradiated back grind tape to silicon is, for example, 0.01 N / 20 mm or more. By the ultraviolet irradiation adhesion to silicon being within the above range, excellent peelability can be exhibited after ultraviolet irradiation, and adhesive residue on the adherend can be prevented. In this specification, the ultraviolet irradiation adhesion to silicon refers to the adhesion to silicon measured after irradiating the ultraviolet-cured adhesive layer with ultraviolet light so that the integrated light quantity becomes 700 mJ / cm 2 and is the adhesion to silicon measured after irradiating the ultraviolet-cured adhesive layer with ultraviolet light so that the integrated light quantity becomes 700 mJ / cm

[0014] In one embodiment, the back grind tape preferably further has an intermediate layer. By having an intermediate layer, when the surface of the adherend has irregularities, the embedding property of the irregularities can be further improved. The intermediate layer is disposed between the base material and the adhesive layer. FIG. 1 is a schematic cross-sectional view of a back grind tape according to one embodiment of the present invention. The back grind tape 100 in the illustrated example includes a base material 30, an intermediate layer 20, and an adhesive layer 10.

[0015] The back grind tape may further include any appropriate layer other than the base material, the ultraviolet-cured adhesive layer, and the intermediate layer. For example, it may further include an antistatic layer. By having an antistatic layer, electrostatic breakdown of the semiconductor element due to static electricity during peeling of the back grind tape can be prevented.

[0016] The thickness of the back grind tape can be set within any appropriate range. Preferably it is 10 μm to 1000 μm, more preferably 50 μm to 300 μm, and still more preferably 100 μm to 300 μm.

[0017] B. Base material The base material can be composed of any suitable resin. Specific examples of resins that make up the base material include polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polyolefin resins such as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, polyethylene, polypropylene, and ethylene-propylene copolymer; polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluororesins, polyethers, polystyrene resins such as polystyrene, polycarbonate, and polyethersulfone. Preferably, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate are used. By using these resins, warping can be further prevented.

[0018] The base material may further contain other components, to the extent that it does not impair the effects of the present invention. Examples of other components include antioxidants, ultraviolet absorbers, light stabilizers, and heat stabilizers. The type and amount of other components used can be any appropriate amount depending on the purpose.

[0019] In one embodiment, the substrate has an antistatic function. By having an antistatic function in the substrate, the generation of static electricity when the tape is peeled off can be suppressed, preventing circuit damage due to static electricity and the adhesion of foreign matter. The substrate may have an antistatic function by being formed from a resin containing an antistatic agent, or it may have an antistatic function by forming an antistatic layer on any suitable film by coating it with a composition containing an antistatic component such as a conductive polymer, an organic or inorganic conductive substance, and an antistatic agent. When the substrate has an antistatic layer, it is preferable that an intermediate layer is laminated on the surface on which the antistatic layer is formed.

[0020] If the substrate has an antistatic function, the surface resistance value of the substrate is, for example, 1.0 × 10⁻⁶. 2Ω / sq ~ 1.0×10 13 Ω / sq, preferably 1.0×10 6 Ω / sq ~ 1.0×10 12 Ω / sq, more preferably 1.0×10 7 Ω / sq ~ 1.0×10 11 Ω / sq. When the surface resistance value is within the above range, generation of static electricity during tape peeling can be suppressed, and destruction of the circuit and adhesion of foreign matter due to static electricity can be prevented. When using a substrate having an antistatic function as the substrate, the surface resistance value of the obtained back grind tape can be, for example, 1.0×10 6 Ω / sq ~ 1.0×10 12 Ω / sq.

[0021] The thickness of the substrate can be set to any appropriate value. The thickness of the substrate is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm.

[0022] The elastic modulus of the substrate can be set to any appropriate value. The elastic modulus of the substrate is preferably 50 MPa to 6000 MPa, more preferably 70 MPa to 5000 MPa. When the elastic modulus is within the above range, a back grind tape that can moderately follow the unevenness on the surface of the adherend can be obtained.

[0023] C. UV curable adhesive layer The UV curable adhesive layer can be formed using any appropriate adhesive composition. Typically, the adhesive composition includes a base polymer, a photoinitiator, and a crosslinking agent. The UV curable adhesive layer irradiated with ultraviolet rays preferably has a tensile storage modulus E'1 at 25°C of 200 MPa or less and a tensile storage modulus E'2 at 60°C of 30 MPa or less. By having such properties, excellent unevenness embedding property can be exhibited even when the adherend has unevenness.

[0024] The 60°C tensile storage modulus E'2 of the UV-curable adhesive layer irradiated with ultraviolet light is preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 15 MPa or less. Furthermore, the 60°C tensile storage modulus E'2 of the UV-curable adhesive layer irradiated with ultraviolet light is preferably 5 MPa or more. By having the 25°C tensile storage modulus E'1 and 60°C tensile storage modulus E'2 of the UV-curable adhesive layer irradiated with ultraviolet light within the above ranges, excellent surface filling properties can be achieved in the backgrinding process, even when the adherend has irregularities.

[0025] The 80°C shear storage modulus G'2 of the UV-curable adhesive layer without UV irradiation is preferably 0.01 MPa to 1 MPa, more preferably 0.05 MPa to 0.5 MPa, and even more preferably 0.1 MPa to 0.4 MPa. Having the 80°C shear storage modulus G'2 of the UV-curable adhesive layer without UV irradiation within this range allows for excellent surface filling even when the adherend has irregularities.

[0026] C-1. Base Polymer As the base polymer, any suitable resin used in adhesive compositions can be used. Examples include (meth)acrylic resins, vinyl alkyl ether resins, silicone resins, polyester resins, polyamide resins, urethane resins, and styrene-diene block copolymers. Preferably, (meth)acrylic resins are used. By using (meth)acrylic resins, it is possible to easily adjust the storage modulus and tensile modulus of the adhesive layer, and to obtain an adhesive composition with an excellent balance between tackiness and release properties. Furthermore, contamination of the adherend by components derived from the adhesive can be reduced. Note that "(meth)acrylic" refers to acrylic and / or methacrylic.

[0027] In one embodiment, the adhesive composition preferably includes as a base polymer a polymer obtained by polymerizing a monomer composition (hereinafter also referred to as a base polymer monomer composition) which contains a polymer having a hydroxyl group and a monomer represented by formula (1). By including such a base polymer, an adhesive composition can be obtained that has excellent surface-filling properties and adhesiveness, and that prevents adhesive residue from being left on the adherend when peeled off. By polymerizing the components contained in the base polymer monomer composition, the monomer represented by formula (1) can be added to the polymer having a hydroxyl group through addition polymerization. As a result, a polymer having structural units derived from the monomer represented by formula (1) is obtained. By using this polymer as a base polymer, an adhesive composition can be obtained that has excellent surface-filling properties and adhesiveness, and that prevents adhesive residue from being left on the adherend when peeled off. [ka] (In the formula, n is an integer greater than or equal to 1).

[0028] The base polymer is obtained, for example, by polymerizing a monomer composition comprising an ester of acrylic acid or methacrylic acid having any suitable linear or branched alkyl group and any suitable copolymer component. The ester of acrylic acid or methacrylic acid having a linear or branched alkyl group may be used alone or in combination of two or more.

[0029] The linear or branched alkyl groups are preferably alkyl groups having 30 or fewer carbon atoms, more preferably alkyl groups having 1 to 20 carbon atoms, and even more preferably alkyl groups having 4 to 18 carbon atoms. Specific examples of alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, heptyl group, cyclohexyl group, 2-ethylhexyl group, octyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group, dodecyl group, and the like.

[0030] The weight-average molecular weight of the base polymer is preferably 300,000 or more, more preferably 400,000 or more, and even more preferably 600,000 to 1,000,000. Within this range, bleeding of low molecular weight components can be prevented, and a low-contamination adhesive composition can be obtained. The molecular weight distribution (weight-average molecular weight / number-average molecular weight) of the base polymer is preferably 1 to 20, and more preferably 3 to 10. By using a base polymer with a narrow molecular weight distribution, bleeding of low molecular weight components can be prevented, and a low-contamination adhesive composition can be obtained. The weight-average molecular weight and number-average molecular weight can be determined by gel permeation chromatography (solvent: tetrahydrofuran, polystyrene equivalent).

[0031] As the polymer having hydroxyl groups, any suitable polymer into which hydroxyl groups have been introduced can be used. Examples include polymers in which hydroxyl groups have been introduced to the side chains and / or terminals of resins such as (meth)acrylic resins, vinyl alkyl ether resins, silicone resins, polyester resins, polyamide resins, urethane resins, and styrene-diene block copolymers. Preferably, a (meth)acrylic resin into which hydroxyl groups have been introduced is used. By using a (meth)acrylic resin, it is easy to adjust the storage modulus and tensile modulus of the adhesive layer, and an adhesive composition with an excellent balance between tackiness and release properties can be obtained. Furthermore, contamination of the adherend by components derived from the adhesive can be reduced. Note that "(meth)acrylic" refers to acrylic and / or methacrylic.

[0032] Any suitable monomer can be used as the hydroxyl group-containing monomer. Examples include 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, and N-(2-hydroxyethyl)acrylamide. Preferably, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxymethyl methacrylate, and 2-hydroxyethyl methacrylate are used. These monomers may be used individually or in combination of two or more.

[0033] The hydroxyl group-containing monomer is preferably 10 mol% to 40 mol%, more preferably 10 mol% to 30 mol%, and even more preferably 15 mol% to 25 mol%, based on 100 mol% of the total monomer components of the monomer composition used for polymerization of polymers having hydroxyl groups. By polymerizing the monomer composition containing the hydroxyl group-containing monomer, a polymer having hydroxyl groups is obtained. This hydroxyl group can serve as an introduction point for structural units derived from the monomer represented by formula (1). For example, by reacting a polymer having hydroxyl groups (prepolymer) with the monomer represented by formula (1), a base polymer having carbon unsaturated double bonds is obtained.

[0034] For the purpose of modifying cohesiveness, heat resistance, crosslinkability, etc., other monomer components copolymerizable with the above alkyl (meth)acrylate may be used as needed. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid and methacrylic acid; acid anhydride monomers such as maleic anhydride and eicotanoic anhydride; sulfonic acid group-containing monomers such as styrene sulfonic acid and allyl sulfonic acid; (N-substituted) amide monomers such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate; maleimide monomers such as N-cyclohexyl maleimide and N-isopropyl maleimide; itaconimide monomers such as N-methylitaconimide and N-ethylitaconimide; succinimide monomers Examples include vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, and methylvinylpyrrolidone; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate; acrylic ester monomers having heterocycles, halogen atoms, silicon atoms, etc., such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; olefin monomers such as isoprene, butadiene, and isobutylene; and vinyl ether monomers such as vinyl ether. These monomer components may be used individually or in combination of two or more.

[0035] The proportion of other monomeric components copolymerizable with (meth)acrylate alkyl ester in the monomer composition can be any appropriate amount. Specifically, the other monomeric components copolymerizable with (meth)acrylate alkyl ester are used such that the total of the (meth)acrylate alkyl ester, the hydroxyl group-containing monomer, and any other monomeric component copolymerizable with (meth)acrylate alkyl ester is 100 mol%.

[0036] Polymers having hydroxyl groups can be obtained by any suitable method. For example, they can be obtained by polymerizing a monomer composition comprising an alkyl (meth)acrylate, a hydroxyl group-containing monomer, and other monomer components copolymerizable with any alkyl (meth)acrylate by any suitable polymerization method.

[0037] As described above, the base polymer of the adhesive composition is a polymer obtained by polymerizing a monomer composition containing the polymer having a hydroxyl group and the monomer represented by formula (1). That is, the base polymer is a polymer having a structure derived from the monomer represented by formula (1). By addition polymerization of the hydroxyl group of the polymer having a hydroxyl group and the isocyanate group of the monomer represented by formula (1), a base polymer in which a carbon unsaturated double bond has been introduced is obtained. By using this base polymer, an adhesive composition can be obtained that has excellent surface-filling properties and adhesiveness, and that can prevent adhesive residue from being left on the adherend when peeled off. [ka] (In the formula, n is an integer greater than or equal to n).

[0038] In formula (1), n ​​is an integer of 1 or more, preferably 1 to 10, and more preferably 1 to 5. By having n within the above range, an adhesive composition with further suppression of adhesive residue can be provided. In one embodiment, the monomer represented by formula (1) is 2-(2-methacryloyloxyethyloxy)ethyl isocyanate (a compound in formula (1) where n is 1). Only one monomer represented by formula (1) may be used, or two or more may be used in combination.

[0039] The amount of monomer represented by formula (1) added relative to the number of moles of hydroxyl groups in a polymer having hydroxyl groups is preferably 60 mol% to 95 mol%, more preferably 65 mol% to 90 mol%, and even more preferably 70 mol% to 85 mol%. By having the amount of monomer represented by formula (1) added within the above range, the adhesive composition can be cured by ultraviolet irradiation, and an adhesive composition with excellent release properties can be obtained. If the amount of monomer represented by formula (1) added exceeds 95 mol%, the number of reaction sites with the crosslinking agent decreases, and a sufficient crosslinking effect may not be obtained.

[0040] The base polymer may have a portion into which a carbon-unsaturated double bond has been introduced using a compound having a carbon-unsaturated double bond other than the monomer represented by formula (1). Examples of compounds having a carbon-unsaturated double bond other than the monomer represented by formula (1) include 2-isocyanate ethyl acrylate (2-acryloyloxyethyl isocyanate), 2-isocyanate ethyl methacrylate (2-methacryloyloxyethyl isocyanate), methacryloisocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. These may be used individually or in combination of two or more. When a compound having a carbon-unsaturated double bond other than the monomer represented by formula (1) is also used, the total amount of the monomer represented by formula (1) and the compound having a carbon-unsaturated double bond other than the monomer represented by formula (1) should be 95 mol% or less.

[0041] C-2. Photopolymerization Initiator Any suitable initiator can be used as a photopolymerization initiator. Examples of photopolymerization initiators include: acylphosphine oxide photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphine and (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and benzyldimethyl ketal, etc. Examples include ketal compounds; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone 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; and α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1. Preferably, 2,2-dimethoxy-2-phenylacetophenone or 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1 can be used. One photopolymerization initiator may be used alone, or two or more may be used in combination.

[0042] Commercially available photopolymerization initiators may be used. Examples include Omnirad 127D and Omnirad 651, both manufactured by IGM Resins.

[0043] The photopolymerization initiator can be used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer. If the content of the photopolymerization initiator is less than 0.5 parts by weight, the material may not cure sufficiently when irradiated with active energy rays. If the content of the photopolymerization initiator exceeds 20 parts by weight, the storage stability of the adhesive composition may decrease.

[0044] C-3. Additives The adhesive composition may further contain any suitable additives. Examples of additives include crosslinking agents, catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, antioxidants, conductive materials, UV absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, and solvents.

[0045] In one embodiment, the adhesive composition may further contain a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and chelate-based crosslinking agents. The content of the crosslinking agent can be adjusted to any appropriate amount. For example, when using an isocyanate-based crosslinking agent, the content is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 3.0 to 5.0 parts by weight, per 100 parts by weight of the base polymer. The flexibility of the UV-curable adhesive layer formed by the adhesive composition can be controlled by the content of the crosslinking agent. If the crosslinking agent content is less than 0.01 parts by weight, the adhesive composition may become sol-like and may not be able to form a UV-curable adhesive layer. If the crosslinking agent content exceeds 10 parts by weight, the adhesion to the adherend may decrease and the adherend may not be adequately protected.

[0046] In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a variety of functional groups. Particularly preferred is a crosslinking agent having three or more isocyanate groups. By using an isocyanate-based crosslinking agent and setting the content of the crosslinking agent within the above range, it is possible to form an ultraviolet-curable adhesive layer that exhibits excellent peelability and significantly less adhesive residue even after heating.

[0047] The thickness of the UV-curable adhesive layer can be set to any appropriate value. Preferably, the thickness of the UV-curable adhesive layer is 1 μm to 100 μm, more preferably 1 μm to 80 μm, even more preferably 1 μm to 50 μm, and particularly preferably 1 μm to 20 μm. By having the thickness of the UV-curable adhesive layer within the above range, sufficient adhesive strength can be achieved to the adherend.

[0048] The UV-curable adhesive layer may be one layer or two or more layers. Alternatively, it may be a laminate of a UV-curable adhesive layer and a non-UV-curable adhesive layer. If there are two or more UV-curable adhesive layers, at least one UV-curable adhesive layer formed using the above-mentioned adhesive composition is sufficient. If there are two or more UV-curable adhesive layers, it is preferable that the UV-curable adhesive layer formed using the above-mentioned adhesive composition is formed on the surface of the backgrind tape that contacts the adherend. Adhesive layers not formed by the above-mentioned adhesive composition can be formed with any suitable adhesive composition. This adhesive composition may be a UV-curable adhesive or a pressure-sensitive adhesive.

[0049] D. middle class In one embodiment, the backgrind tape further has an intermediate layer. The intermediate layer is placed between the substrate and the UV-curable adhesive layer. The presence of the intermediate layer in the backgrind tape can provide better surface filling capabilities.

[0050] The thickness of the intermediate layer is preferably 10 μm to 300 μm, more preferably 50 μm to 200 μm, even more preferably 50 μm to 150 μm, and particularly preferably 100 μm to 150 μm. By having the intermediate layer thickness within the above range, a backgrind tape that can effectively fill uneven surfaces can be obtained.

[0051] The shear storage modulus G'3 of the intermediate layer at 25°C is preferably 0.3 MPa to 10 MPa, more preferably 0.4 MPa to 1.5 MPa, and even more preferably 0.5 MPa to 1.0 MPa. Furthermore, the shear storage modulus G'4 of the intermediate layer at 80°C is preferably 0.01 MPa to 0.5 MPa, more preferably 0.02 MPa to 0.20 MPa, even more preferably 0.03 MPa to 0.15 MPa, and particularly preferably 0.04 MPa to 0.10 MPa. By having the shear storage modulus G'3 at 25°C and the shear storage modulus G'4 at 80°C within the above ranges, a back-grind tape that can effectively fill uneven surfaces during application and the back-grinding process can be obtained.

[0052] The intermediate layer can be formed from any suitable material. For example, the intermediate layer may be formed from resins such as acrylic resins, polyethylene resins, ethylene-vinyl alcohol copolymers, ethylene vinyl acetate resins, and ethylene methyl methacrylate resins, or from adhesives.

[0053] In one embodiment, the intermediate layer is formed from an intermediate layer-forming composition comprising a (meth)acrylic polymer. Preferably, the (meth)acrylic polymer comprises a component derived from alkyl (meth)acrylate. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate. Examples of C1-C20 alkyl esters of (meth)acrylate include acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0054] The (meth)acrylic polymer may, if necessary, contain constituent units corresponding to other monomers copolymerizable with the alkyl (meth)acrylate, for the purpose of modifying properties such as cohesiveness, heat resistance, and crosslinkability. Examples of such monomers include: carboxyl group-containing monomers such as acrylic acid and methacrylic acid; acid anhydride monomers such as maleic anhydride and eicotanoic anhydride; hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; sulfonic acid group-containing monomers such as styrene sulfonic acid and allyl sulfonic acid; nitrogen-containing monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and acryloylmorpholine; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate; maleimide monomers such as N-cyclohexyl maleimide and N-isopropyl maleimide; and N-methyl itaconimide and N-ethyl itaconimide. Examples include itaconiaimide monomers such as mid; succinimide monomers; vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, and methylvinylpyrrolidone; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate; acrylic ester monomers having heterocycles, halogen atoms, silicon atoms, etc., such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; olefin monomers such as isoprene, butadiene, and isobutylene; and vinyl ether monomers such as vinyl ether. These monomer components may be used individually or in combination of two or more. The content of the constituent units derived from the above other monomers is preferably 1 to 30 parts by weight, and more preferably 3 to 25 parts by weight, per 100 parts by weight of the acrylic polymer.

[0055] The weight-average molecular weight of the above (meth)acrylic polymer is preferably 200,000 to 1,000,000, and more preferably 300,000 to 800,000. The weight-average molecular weight can be measured by GPC (solvent: THF).

[0056] The glass transition temperature of the above (meth)acrylic polymer is preferably -50°C to 30°C, and more preferably -40°C to 20°C. Within this range, a backgrind tape with excellent heat resistance that can be suitably used in heating processes can be obtained.

[0057] In one embodiment, the intermediate layer contains a photopolymerization initiator but does not contain an UV-curable component. That is, although it contains a photopolymerization initiator, the intermediate layer itself does not harden upon UV irradiation. Therefore, the intermediate layer can maintain its flexibility before and after UV irradiation. Furthermore, because the intermediate layer contains a photopolymerization initiator, the photopolymerization initiator contained in the adhesive layer migrates to the intermediate layer, and as a result, the decrease in the amount of photopolymerization initiator contained in the adhesive layer over time can be suppressed. Therefore, after UV irradiation, the backgrind tape can exhibit excellent easy peelability. In this specification, an UV-curable component refers to a component that can crosslink and harden and shrink upon UV irradiation. Specifically, this includes polymers having carbon unsaturated double bonds in their side chains or terminals.

[0058] The photopolymerization initiator contained in the intermediate layer forming composition (the resulting intermediate layer) may be the same as or different from the photopolymerization initiator contained in the adhesive layer. Preferably, the intermediate layer contains the same photopolymerization initiator as the adhesive layer. By having the intermediate layer and the adhesive layer contain the same photopolymerization initiator, the migration of the photopolymerization initiator from the adhesive layer to the intermediate layer can be further suppressed. As the photopolymerization initiator, the photopolymerization initiators exemplified in the adhesive composition above can be used. Only one type of photopolymerization initiator may be used, or two or more types may be used in combination.

[0059] The amount of photopolymerization initiator in the intermediate layer is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 8 parts by weight, per 100 parts by weight of polymer components in the intermediate layer forming composition. By having the photopolymerization initiator content in the intermediate layer within the above range, a backgrind tape with excellent easy peelability after UV irradiation can be obtained. In one embodiment, the amount of photopolymerization initiator is used in an amount equal to that of the composition forming the adhesive layer.

[0060] In one embodiment, the intermediate layer forming composition further comprises a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, amine-based crosslinking agents, and the like.

[0061] If the intermediate layer forming composition contains a crosslinking agent, the content of the crosslinking agent is preferably 0.5 to 10 parts by weight, and more preferably 1 to 8 parts by weight, per 100 parts by weight of the polymer components in the intermediate layer forming composition.

[0062] The intermediate layer forming composition may further contain any suitable additives as needed. Examples of additives include active energy ray polymerization accelerators, radical scavengers, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

[0063] E. Method for manufacturing backgrind tape Backgrind tape can be manufactured by any suitable method. In one embodiment, backgrind tape can be manufactured by forming an ultraviolet-curable adhesive layer on a substrate. If the backgrind tape has an intermediate layer, it can be manufactured, for example, by forming an intermediate layer on a substrate and then forming an adhesive layer on the intermediate layer. The adhesive layer and the intermediate layer may be formed by coating the substrate or intermediate layer with the composition for forming the adhesive layer and the composition for forming the intermediate layer, respectively, or by forming each layer on any suitable release liner and then transferring it. Various coating methods can be used, 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. Alternatively, a method may be used in which the adhesive layer or intermediate layer is formed on a release liner separately and then bonded to the substrate.

[0064] F. Uses of backgrind tape The backgrind tape according to the embodiment of the present invention can be suitably used in the backgrinding process of semiconductor device manufacturing. The backgrind tape is required to properly hold the silicon wafer during backgrinding and to have easy peelability so that the ground wafer can be peeled off without damaging it. The backgrind tape according to the embodiment of the present invention has excellent surface-filling and adhesive properties before UV irradiation, and exhibits excellent easy peelability after UV irradiation, preventing adhesive residue from remaining on the surface of the adherend. Therefore, the backgrind tape according to the embodiment of the present invention can be suitably used in the processing process of semiconductor devices.

[0065] The backgrind tape of the embodiment of the present invention is preferably used by being attached to an adherend having irregularities (e.g., bumps). As described above, the backgrind tape of the embodiment of the present invention has excellent irregularity-filling ability and adhesive strength when not irradiated with ultraviolet light, i.e., before ultraviolet irradiation. Therefore, even if the adherend has irregularities, the adherend (e.g., silicon wafer) can be properly held during the backgrinding process. Furthermore, when using a backgrind tape with excellent irregularity-filling ability on an adherend with irregularities, adhesive residue may be left on the irregular areas. The backgrind tape of the embodiment of the present invention can exhibit excellent easy peelability after ultraviolet irradiation. Therefore, even if the adherend has irregularities, adhesive residue on the adherend surface can be prevented.

[0066] In one embodiment, the step height of the uneven substrate is preferably 10 μm to 200 μm, more preferably 30 μm to 150 μm, and even more preferably 50 μm to 100 μm. For substrates with step heights in the above range, it can be difficult to achieve both excellent substrate-filling properties and easy peelability. The backgrind tape of the embodiment of the present invention exhibits excellent substrate-filling properties and adhesiveness even on such substrates, and can prevent adhesive residue when peeled off.

[0067] In one embodiment, the distance between the protrusions (e.g., bumps or protruding electrodes) of an uneven substrate is preferably 10 μm to 500 μm, more preferably 30 μm to 300 μm, and even more preferably 60 μm to 200 μm. In substrates where the distance between the protrusions is within the above range, the uneven portions become dense, making it difficult to achieve both excellent surface-filling properties and easy peelability. According to the backgrind tape of the embodiment of the present invention, excellent surface-filling properties and adhesiveness can be exhibited even on such substrates, and adhesive residue can be prevented when peeled off.

[0068] In one embodiment, the above-mentioned irregularities are protruding electrodes. The protruding electrodes are formed from any suitable metal. Examples of metals include tin, copper, nickel, and gold. Because the surface composition of the protruding electrodes and the silicon wafer are different, even if the backgrind tape is applied, sufficient filling of the irregularities may not be obtained, and the silicon wafer, which is the adherend, may not be adequately held during the backgrinding process. According to the backgrind tape of the embodiment of the present invention, even if the adherend surface has parts composed of different compositions, the adherend can be adequately held during the backgrinding process. [Examples]

[0069] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The test and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" are based on weight.

[0070] <Manufacturing Example 1> Preparation of Intermediate Layer Forming Composition A monomer composition (solid content: 25%) was prepared by mixing 58.4 moles of butyl acrylate, 38.6 moles of methyl methacrylate, and 3 moles of 2-hydroxyethyl acrylate (manufactured by Toagosei Co., Ltd., trade name: Acrylics® HEA), along with 0.3% by weight of polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: V-50) relative to the total weight of the monomers, and a solvent (water). The monomer composition was placed in a 1 L round-bottom separable flask into a polymerization apparatus equipped with a separable cover, separatory funnel, thermometer, nitrogen inlet tube, Liebig condenser, vacuum seal, stirring rod, and stirring blade, and nitrogen was purged at room temperature for 1 hour while stirring. Subsequently, emulsion polymerization was carried out by introducing nitrogen and maintaining the mixture at 56°C for 5 hours while stirring, followed by salting out to obtain a resin (polymer for intermediate layer forming composition). The obtained polymer was dissolved in ethyl acetate, and 0.1 parts by weight of a polyisocyanate compound (trade name "Coronate L", manufactured by Tosoh Corporation) and 1 part by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name: Omnirad 127D) were mixed with 100 parts by weight of the solids content of this solution to prepare an intermediate layer forming composition (solids content 35%) containing ethyl acetate.

[0071] <Manufacturing Example 2> Preparation of Adhesive Layer Forming Composition A monomer composition (solid content: 37.5%) was prepared by mixing 75 moles of butyl acrylate, 25 moles of methyl methacrylate, and 20 moles of 2-hydroxyethyl acrylate (manufactured by Toagosei Co., Ltd., trade name: Acrylics® HEA), with 0.3% by weight of polymerization initiator (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: 2,2'-azobis(isobutyronitrile) (AIBN)) relative to the total weight of the monomers, and a solvent (ethyl acetate). The monomer composition was placed in a 1 L round-bottom separable flask into a polymerization apparatus equipped with a separable cover, separatory funnel, thermometer, nitrogen inlet tube, Liebig condenser, vacuum seal, stirring rod, and stirring blade, and nitrogen was purged at room temperature for 6 hours while stirring. Subsequently, solution polymerization was carried out by introducing nitrogen and maintaining the mixture at 65°C for 6 hours while stirring to obtain a resin solution (polymer solution containing a polymer having hydroxyl groups). After stirring the hydroxyl group-containing polymer solution obtained above to allow sufficient air to enter, 16 moles of the monomer represented by formula (1) (manufactured by Showa Denko Corporation, trade name "Karenz MOI-EG") were added. Furthermore, 0.05% by weight of dibutyltin IV dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added relative to the weight of the monomer represented by formula (1), and solvent (ethyl acetate) was added as appropriate to adjust the solid content concentration to 31%, and the mixture was stirred. After that, it was stored at 50°C for 24 hours to obtain the polymer solution (adhesive composition 1). To 100 parts by weight of the solids content of the obtained polymer solution, 3.0 parts by weight of a polyisocyanate compound (trade name "Coronate L", manufactured by Tosoh Corporation) and 1 part by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name: Omnirad 127D) were mixed to prepare an adhesive layer-forming composition containing ethyl acetate (solids content 15%).

[0072] [Example 1] The adhesive composition obtained in Production Example 1 was applied to the silicone-treated surface of a 38 μm thick polyester release liner (product name "MRF", manufactured by Mitsubishi Plastics, Inc.), and the solvent was removed by heating at 120°C for 120 seconds to form a 150 μm thick intermediate layer. Next, the ESAS-treated surface of a 50 μm thick PET film (product name "Lumirror S105", manufactured by Toray Industries, Inc.) was laminated to the surface of the intermediate layer as a substrate. Separately, the adhesive layer-forming composition obtained in Production Example 2 was applied to the silicone-treated surface of a 75 μm thick polyester-based release liner, heated at 120°C for 120 seconds to remove the solvent, and an adhesive layer with a thickness of 6 μm was formed. Next, the release liner was peeled off from the intermediate layer, the adhesive layer was bonded to the intermediate layer and transferred, and the tape was stored at 50°C for 72 hours to obtain an adhesive tape having the base material / intermediate layer / adhesive layer in this order.

[0073] [Example 2] An adhesive tape was obtained in the same manner as in Example 1, except that the amount of monomer represented by formula (1) (manufactured by Showa Denko Corporation, trade name "Kalenz MOI-EG") added was changed to 14 moles.

[0074] [Example 3] An adhesive tape was obtained in the same manner as in Example 1, except that the amount of monomer represented by formula (1) (manufactured by Showa Denko, trade name "Kalenz MOI-EG") added was changed to 18 moles, and the amount of photopolymerization initiator added was 2 parts by weight.

[0075] (Comparative Example 1) An adhesive tape was obtained in the same manner as in Example 3, except that a compound introducing another carbon unsaturated double bond (manufactured by Showa Denko, trade name "Kalenz MOI") was used instead of the monomer represented by formula (1) (manufactured by Showa Denko, trade name "Kalenz MOI-EG"), and the amount of photopolymerization initiator added was 1 part by weight.

[0076] (Comparative Example 2) A monomer composition (solid content concentration: 40%) was prepared by mixing 75 moles of 2-ethylhexyl acrylate, 25 moles of acryloylmorpholine, 22 moles of 2-hydroxyethyl acrylate (manufactured by Toagosei Co., Ltd., trade name: Acrylics® HEA), 0.3% by weight of polymerization initiator (manufactured by Nippon Oil & Fats Co., Ltd., trade name: Niper® BW) relative to the total weight of monomers, and a solvent (ethyl acetate). The monomer composition was placed in a 1 L round-bottom separable flask into a polymerization apparatus equipped with a separable cover, separatory funnel, thermometer, nitrogen inlet tube, Liebig condenser, vacuum seal, stirring rod, and stirring blade, and nitrogen was purged at room temperature for 6 hours while stirring. Subsequently, polymerization was carried out by inflowing nitrogen and stirring at 60°C for 8 hours to obtain a resin solution. 11 moles of another compound that introduces a carbon unsaturated double bond (manufactured by Showa Denko Corporation, trade name "Karens MOI") was added to the obtained resin solution. Furthermore, 0.0633 parts by weight of dibutyltin IV dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and solvent (toluene) was added as needed to adjust the solid content concentration to 15%. Then, the mixture was stirred at 50°C for 24 hours under an air atmosphere to obtain a polymer solution (adhesive composition). An adhesive layer-forming composition was prepared in the same manner as in Example 1, except that the amount of photopolymerization initiator added was 5 parts by weight, using the obtained adhesive composition. An adhesive tape was obtained in the same manner as in Example 1, except that this adhesive composition was used.

[0077] (Comparative Example 3) A polymer solution (adhesive composition) was obtained in the same manner as in Comparative Example 2, except that 18 moles of another compound that introduces a carbon unsaturated double bond (Showa Denko Corporation, trade name "Kalenz MOI") were used. An adhesive layer-forming composition was prepared in the same manner as in Example 1, except that the amount of photopolymerization initiator added was 5 parts by weight, using the obtained adhesive composition. An adhesive tape was obtained in the same manner as in Example 1, except that this adhesive composition was used.

[0078] The following evaluations were performed using the adhesive tapes obtained in the examples and comparative examples. The results are shown in Table 1. (1) Adhesive strength The silicon adhesive strength (Si adhesive strength) was measured using a Si mirror wafer (manufactured by Shin-Etsu Chemical Co., Ltd.) as the adherend. The adhesive tape was cut to a width of 20 mm with a cutter. The tape was attached to the wafer by passing a 2 kg roller back and forth once. The measurement was performed in accordance with JIS Z 0237 (2000) using a tensile testing machine (Tensilon) (manufactured by MinebeaMitsumi Co., Ltd., product name: TG-1kN). Specifically, the tape was peeled off at a tensile speed of 300 mm / min, at room temperature, and at a peeling angle of 180°. For UV irradiation, the adhesive tape was attached, stored at room temperature for 30 minutes, and then irradiated with UV (700 mJ / cm²) using a high-pressure mercury lamp before measuring the adhesive strength. 2 The procedure was carried out under the following conditions: The application and removal of adhesive tape was performed in an environment with a room temperature of 23°C and a relative humidity of 50%.

[0079] (2) Shear storage modulus Each adhesive layer-forming composition was laminated onto a release liner (38 μm thick, manufactured by Mitsubishi Plastics, product name: MRF) to a thickness of 1 mm, and used as a sample. This sample was measured using an ARES rheometer (manufactured by Waters) under the conditions of a heating rate of 5°C / min, a frequency of 1 Hz, and a measurement temperature of 0°C to 100°C.

[0080] (3) Tensile storage modulus Samples were prepared in the same manner as the evaluation of the shear storage modulus described above. Using these samples, measurements were performed with a dynamic viscoelasticity analyzer (product name: RSA, manufactured by TA Instruments) under the conditions of a heating rate of 5°C / min, a frequency of 1 Hz, and a measurement temperature of 0°C to 100°C. After lamination of the adhesive composition, UV irradiation (700 mJ / cm²) was performed using a high-pressure mercury lamp. 2 Measurements were taken on the items that were (as described above).

[0081] (4) Implantability The adhesive tapes (230 cm x 400 cm) obtained in the examples and comparative examples were attached to wafers (8 inch, bump height 75 μm, diameter 90 μm, pitch 200 μm) using a tape application device (manufactured by Nitto Seiki Co., Ltd., product name: DR-3000III). The attachment was carried out under the following conditions. Operating environment: 23°C, 50% relative humidity Roller pressure: 0.40 MPa Roller speed: 5 mm / second Table temperature: 80℃ After application, the adhesion state of the adhesive tape and wafer was observed using a laser microscope (magnification: 100x). Additionally, images were taken of the adhesive tape and wafer with the tape facing upwards, and the images were binarized (8-bit grayscale, brightness: 0-255, threshold: 114) using image analysis software (Image J (free software)). Five bumps were arbitrarily selected, and the number of dots used to display each bump was measured. Bumps with an average dot count of 830 or less were evaluated as ○ (good), and those with an average dot count exceeding 830 were evaluated as × (poor). Note that the image of only the bumps without tape has 220 dots. With tape, the number of dots will be greater than 220. An average dot count of 830 or less indicates excellent bump-filling ability of the tape.

[0082] (5) Adhesive residue The adhesive tapes (230 cm x 400 cm) obtained in the examples and comparative examples were applied to wafers (12 inches, bump height 65 μm, diameter 60 μm, pitch 150 μm) having bumps composed of Cu pillars and solder, using a tape application device (manufactured by Nitto Seiki Co., Ltd., product name: DR-3000III). The application was carried out under the following conditions. Operating environment: 23°C, 50% relative humidity Roller pressure: 0.40 MPa Roller speed: 5 mm / second Table temperature: 80℃ Next, UV irradiation (700 mJ / cm²) is performed using a high-pressure mercury lamp. 2 The adhesive tape was then peeled off using a peeling device (manufactured by Nitto Seiki Co., Ltd., product name: RM300-NV4) under the following conditions. Peeling temperature: 60℃ Peeling speed: 5 mm / second Subsequently, the wafers after the adhesive tape was removed were observed with a laser microscope. If there was no adhesive residue on the bumps, it was evaluated as ◎ (best), if a small amount of adhesive residue was observed but within an acceptable range, it was evaluated as ○ (amount), and if there was adhesive residue on the bumps and the wafer was unusable, it was evaluated as × (unacceptable).

[0083] [Table 1] [Industrial applicability]

[0084] The backgrind tape of the embodiment of the present invention can be suitably used in semiconductor processing steps. [Explanation of Symbols]

[0085] 10 Adhesive layer 20 Middle Class 30 Base material 100 Backgrind Tape

Claims

1. A backgrind tape having a base material and an ultraviolet-curable adhesive layer, The substrate and the UV-curable adhesive layer are further disposed between them, and the intermediate layer having a thickness of 10 μm to 300 μm. The UV-curable adhesive layer, when not irradiated with UV light, has a 25°C shear storage modulus G'1 of 0.175 MPa or higher, and a silicone adhesive strength of 1 N / 20 mm or higher. The UV-curable adhesive layer of the backgrind tape, after UV irradiation, has a 25°C tensile storage modulus E'1 of 300 MPa or less, and its adhesive strength to silicone is 0.15 N / 20 mm or less. The UV-curable adhesive layer is a layer formed from an adhesive composition containing a base polymer, The base polymer is a polymer obtained by adding a monomer represented by formula (1) to a polymer having a hydroxyl group, in the backgrind tape: 【Chemistry 1】 (In the formula, n is an integer greater than or equal to 1).

2. The backgrind tape according to claim 1, which is used by being attached to a substrate having an uneven surface.

3. The backgrind tape according to claim 2, wherein the step difference of the aforementioned irregularities is 10 μm to 200 μm.

4. The backgrind tape according to claim 2, wherein the aforementioned irregularities are protruding electrodes.

5. The shear storage modulus G'3 of the aforementioned intermediate layer at 25°C is 0.3 MPa to 10 MPa, and The backgrind tape according to claim 1, wherein the shear storage modulus G'4 of the intermediate layer at 80°C is 0.01 MPa to 0.5 MPa.

6. The backgrind tape according to claim 1, wherein the thickness of the ultraviolet-curable adhesive layer is 1 μm to 100 μm.

7. The backgrind tape according to claim 1, wherein the 80°C shear storage modulus G'2 of the UV-curable adhesive layer of the backgrind tape that is not irradiated with UV light is 0.01 MPa to 1 MPa.

8. The backgrind tape according to claim 1, wherein the 60°C tensile storage modulus E'2 of the UV-curable adhesive layer of the backgrind tape irradiated with ultraviolet light is 30 MPa or less.

9. The backgrind tape according to any one of claims 1 to 8, wherein the ultraviolet-curable adhesive layer is a layer formed from an adhesive composition further comprising a photopolymerization initiator.

Images