Adhesive tape for semiconductor wafer processing

Abstract

To provide an adhesive tape for semiconductor wafer processing that is excellent in unevenness-embedding property, and is suppressed from leaving an adhesive residue on a surface of a semiconductor wafer.SOLUTION: The adhesive tape for semiconductor wafer processing includes: a base material; and an adhesive agent layer formed of an active energy ray-curable adhesive agent. A surface free energy X (mN / m) of the adhesive agent layer, and a quotient Y (IA / TA) between a tack value TA (gf) and an integrated value IA (gf sec) of the adhesive agent layer measured by a probe tack method satisfy a relation of formula (1): Y>0.01X-0.21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape for semiconductor wafer processing. [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, large-scale integrated circuits (LSIs) have become increasingly miniaturized and functional, resulting in increasingly complex wafer surface structures. Specifically, solder bumps and other components have made the three-dimensional structure of the wafer surface more complex. For this reason, adhesive tapes used in semiconductor processing must be able to fill in the irregularities on the wafer surface and have strong adhesive properties.

[0003] In recent years, semiconductor wafers have become thinner as various products have become smaller and thinner. For wafers that have been processed to be thinner, if the adhesive strength of the adhesive tape is too high, the wafer may be damaged when the adhesive tape is peeled off. Therefore, to prevent adhesive residue on the adherend and damage to the wafer when the tape is peeled off, adhesive tapes using ultraviolet-curable adhesives have been proposed (e.g., Patent Documents 1 and 2). Furthermore, adhesive tapes with excellent embedding properties for unevenness have been proposed as adhesive tapes suitable for processing semiconductor wafers having uneven structures such as bumps (e.g., Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-017758 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-213075 [Patent Document 3] Japanese Patent Publication No. 2022-121480 Summary of the Invention [Problem to be solved by the invention]

[0005] An adhesive tape having excellent irregularity-burying properties can have the problem of adhesive residue on the semiconductor wafer surface after the adhesive tape is peeled off. The present invention has been made to solve the above-mentioned conventional problems, and aims to provide an adhesive tape for semiconductor wafer processing that has excellent irregularity-burying properties and suppresses adhesive residue on the semiconductor wafer surface. [Means for solving the problem]

[0006] 1. An adhesive tape for semiconductor wafer processing according to an embodiment of the present invention comprises a substrate and an adhesive layer formed of an active energy ray-curable adhesive. The surface free energy X (mN / m) of the adhesive layer and the tack value T of the adhesive layer measured by a probe tack method are A (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) satisfies the relationship of equation (1). Y>0.01X-0.21 (1) 2. In the adhesive tape for semiconductor wafer processing described in 1 above, the active energy ray-curable adhesive contains a (meth)acrylic polymer, and the (meth)acrylic polymer may be a polymer obtained by polymerizing a monomer composition containing 60 mol % or more of a (meth)acrylic monomer having a side chain with 8 or more carbon atoms. 3. In the adhesive tape for semiconductor wafer processing described in 2 above, the monomer composition may contain 39 mol % or less of at least one selected from the group consisting of monomers having a side chain with two or less carbon atoms and highly polar monomers. 4. In the adhesive tape for processing semiconductor wafers described in 3 above, the highly polar monomer may be a hydroxyl group-containing monomer having a side chain with 4 or less carbon atoms. 5. In the adhesive tape for processing semiconductor wafers described in 4 above, the monomer composition may contain 10 mol % to 39 mol % of the hydroxyl group-containing monomer having a side chain with 4 or less carbon atoms. 6. The adhesive tape for semiconductor wafer processing according to any one of 1 to 5 above may further include an intermediate layer. 7. The adhesive tape for semiconductor wafer processing according to any one of the above items 1 to 6 may be a backgrinding tape. [Effects of the Invention]

[0007] According to an embodiment of the present invention, an adhesive tape for semiconductor wafer processing can be provided that has excellent irregularity-filling properties and suppresses adhesive residue on the semiconductor wafer surface. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of an adhesive tape for semiconductor wafer processing according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of an adhesive tape for semiconductor wafer processing according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Overall structure of adhesive tape for semiconductor wafer processing An adhesive tape for semiconductor wafer processing according to an embodiment of the present invention comprises a substrate and an adhesive layer formed of an active energy ray-curable adhesive. FIG. 1 is a schematic cross-sectional view of an adhesive tape for semiconductor wafer processing according to an embodiment of the present invention. In the illustrated example, adhesive tape 100 for semiconductor wafer processing comprises substrate 10 and adhesive layer 20. The adhesive tape for semiconductor wafer processing according to an embodiment of the present invention preferably further comprises an intermediate layer. FIG. 2 is a schematic cross-sectional view of an adhesive tape for semiconductor wafer processing according to another embodiment of the present invention. The adhesive tape for semiconductor wafer processing 100 according to this embodiment comprises, in this order, substrate 10, intermediate layer 30, and adhesive layer 20. In practical terms, a release liner can be releasably temporarily attached to adhesive layer 20 of the adhesive tape for semiconductor wafer processing according to an embodiment of the present invention until use.

[0010] The adhesive tape for semiconductor wafer processing according to an embodiment of the present invention has a surface free energy X (mN / m) of the adhesive layer and a tack value T (measured by a probe tack method) of the adhesive layer. A (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) satisfies the relationship of formula (1). When the relationship of formula (1) is satisfied, an adhesive tape for semiconductor wafer processing can be provided that has excellent irregularity-filling properties and suppresses adhesive residue on the semiconductor wafer surface. Y>0.01X-0.21 (1)

[0011] In this specification, the tack value T of the pressure-sensitive adhesive layer measured by the probe tack method A , and the integral value I A refers to a value measured by the probe tack method using a probe tack tester according to the following procedure. The substrate surface of the adhesive tape is attached to a glass slide via double-sided tape, and the adhesive tape is fixed to the glass slide. Next, a probe with a probe diameter of 5 mm is pressed against the adhesive layer of the adhesive tape at a contact speed of 120 mm / min, a load of 10 gf is applied, and the contact is maintained for 1 second. Next, the probe is pulled up at a peeling speed of 600 mm / min, and the peak value at the time of peeling is taken as the tack value T A (gf), and the peak area is the integral value I A Calculate the values as (gf·sec).

[0012] The adhesive tape for semiconductor wafer processing according to the embodiment of the present invention preferably has a tack value T A (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) satisfies the following formula (2): An adhesive tape for semiconductor wafer processing that satisfies the relationship of formula (2) can be even more excellent in embedding unevenness and can further suppress adhesive residue on the semiconductor wafer surface. Y<0.02X-0.33 (2)

[0013] The adhesive tape for semiconductor wafer processing according to the embodiment of the present invention preferably has a tack value TA (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) satisfies the following formula (3): An adhesive tape for semiconductor wafer processing that satisfies the relationship of formula (3) can be even more excellent in embedding unevenness, and adhesive residue on the semiconductor wafer surface can be further suppressed. Y>-0.012X+0.288 (3)

[0014] The adhesive tape for semiconductor wafer processing according to the embodiment of the present invention preferably has a tack value T A (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) satisfies the following formula (4): An adhesive tape for semiconductor wafer processing that satisfies the relationship of formula (4) can be even more excellent in embedding unevenness, and adhesive residue on the semiconductor wafer surface can be further suppressed. Y<0.0107X-0.1861 (4)

[0015] The adhesive tape for semiconductor wafer processing according to the embodiment of the present invention may further include any appropriate layer other than the substrate, intermediate layer, and adhesive layer. For example, it may further include an antistatic layer. The presence of the antistatic layer can prevent electrostatic damage to semiconductor elements due to static electricity when the adhesive tape for semiconductor wafer processing is peeled off.

[0016] The thickness of the adhesive tape for semiconductor wafer processing can be set to any appropriate range, preferably 10 μm to 1000 μm, more preferably 30 μm to 300 μm, and even more preferably 40 μm to 200 μm.

[0017] B. Base material The substrate may be made of any suitable resin. Specific examples of resins constituting the substrate include polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polyolefin-based 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, cellulose, fluorine-based resins, polyether, and polystyrene-based resins such as polystyrene; polycarbonate; and polyethersulfone. Polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate are preferably used.

[0018] The substrate may further contain other components within the range that does not impair the effects of the present invention. Examples of other components include antioxidants, ultraviolet absorbers, light stabilizers, and heat stabilizers. The other components can be used in any appropriate amount depending on the purpose.

[0019] In one embodiment, the substrate has an antistatic function. If the substrate has an antistatic function, it can suppress the generation of static electricity when peeling off the tape, and prevent the destruction of circuits 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 may have an antistatic function by forming an antistatic layer by applying a composition containing an antistatic component such as a conductive polymer, an organic or inorganic conductive material, and an antistatic agent to any appropriate film. 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. When the substrate has an antistatic function, the surface resistance value of the substrate is, for example, 1.0 × 10 2 Ω / □~1.0×10 13 It is Ω / □.

[0020] The thickness of the substrate can be set to any appropriate value, and is preferably 10 μm to 200 μm, and more preferably 20 μm to 150 μm.

[0021] 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, an adhesive tape for semiconductor wafer processing that can appropriately conform to the irregularities on the adherend surface can be obtained.

[0022] C.Adhesive layer The adhesive layer can be formed using any suitable active energy ray-curable adhesive. Typically, the adhesive contains a base polymer. If the adhesive layer is formed using an active energy ray-curable adhesive, an adhesive tape for semiconductor wafer processing with excellent easy peelability can be obtained.

[0023] The storage modulus of the pressure-sensitive adhesive layer before irradiation with active energy rays is preferably 0.020 MPa to 0.25 MPa, more preferably 0.025 MPa to 0.20 MPa, and even more preferably 0.03 MPa to 0.18 MPa. If the storage modulus is within the above range, the pressure-sensitive adhesive layer can be well adhered to the adherend, which is a semiconductor wafer. The storage modulus of the pressure-sensitive adhesive layer can be measured, for example, using a viscoelasticity measuring device.

[0024] The contact angle of the pressure-sensitive adhesive layer with water is preferably 95° to 125°, more preferably 100° to 120°, and the contact angle of the pressure-sensitive adhesive layer with methylene iodide is preferably 55° to 85°, more preferably 60° to 80°.

[0025] The surface free energy X of the pressure-sensitive adhesive layer can be set to any appropriate value so as to satisfy the above formula (1). The surface free energy X is preferably 10 mN / m to 40 mN / m, more preferably 15 mN / m to 30 mN / m, and even more preferably 20 mN / m to 25 mN / m. When the surface free energy of the pressure-sensitive adhesive layer is within the above range, the affinity with the adherend (semiconductor wafer surface) is adjusted to an appropriate range, the adhesive exerts appropriate adhesive strength when attached to the adherend, and adhesive residue on the adherend after peeling the adhesive tape can be suppressed. In this specification, the surface free energy X of the pressure-sensitive adhesive layer refers to a value calculated by the following method. The contact angle of the pressure-sensitive adhesive layer with water and the contact angle with methylene iodide are measured. The obtained measured values and the surface free energy values (literature values) of the liquids used to measure the contact angles (water or methylene iodide) are substituted into the following formula (I) derived from Young's equation and the extended Fowkes equation. The surface free energy value is calculated by solving two equations obtained from the contact angle with water and the contact angle with methylene iodide as simultaneous linear equations. The surface free energy γS of a solid is γS d and γS v It is the harmony of. (1+cosθ)γ L =2√(γS d γL d )+2√(γ S v gamma L v )···(I) The symbols in the formula are as follows: θ: contact angle gamma L : Contact angle measurement Surface free energy of liquid gamma L d :r L Dispersion force components in gamma L v :r L Polar force component in gamma S d : Dispersion force component in the surface free energy of a solid gamma S v : Polar force component in the surface free energy of a solid

[0026] Tack value T measured by the probe tack method on the adhesive layer A The tack value T of the pressure-sensitive adhesive layer is preferably 150 gf to 900 gf, more preferably 200 gf to 850 gf, and even more preferably 250 gf to 850 gf. A If the tack value T of the pressure-sensitive adhesive layer is within the above range, the pressure-sensitive adhesive layer can adhere well to the semiconductor wafer as an adherend. A can be measured by the method described above.

[0027] Integral value I measured by the probe tack method on the adhesive layer A is preferably 5 gf·sec to 50 gf·sec, and more preferably 5 gf·sec to 45 gf·sec. The integral value I A If is within the above range, the deformation energy of the pressure-sensitive adhesive layer can be increased. A can be measured by the method described above.

[0028] Tack value T A (gf) and the integral value I A (gf·sec) and the quotient Y(I A / T A ) can be set to any appropriate value so as to satisfy the above formula (1). The quotient Y is preferably 0.01 to 0.08, more preferably 0.02 to 0.07, and even more preferably 0.03 to 0.06. When the quotient Y is within the above range, a pressure-sensitive adhesive layer can be obtained that has excellent adhesion to the adherend surface and ability to fill irregularities, and leaves little adhesive residue on the adherend, i.e., semiconductor wafer.

[0029] Any suitable adhesive can be used as the active energy ray-curable adhesive. For example, it may be an adhesive obtained by adding an ultraviolet-curable monomer and / or oligomer to any suitable adhesive such as an acrylic adhesive, a rubber adhesive, a silicone adhesive, or a polyvinyl ether adhesive, or it may be an adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal as the base polymer. Preferably, an adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into the side chain and / or terminal as the base polymer is used.

[0030] When using a pressure-sensitive adhesive using a polymer having a polymerizable carbon-carbon double bond introduced into its side chain and / or terminal, a polymer having a polymerizable carbon-carbon double bond introduced into its side chain and / or terminal and having adhesive properties is used as the base polymer. Examples of such polymers include polymers having a polymerizable carbon-carbon double bond introduced into a resin such as an acrylic resin, a vinyl alkyl ether resin, a silicone resin, a polyester resin, a polyamide resin, a urethane resin, or a styrene-diene block copolymer. Preferably, an acrylic resin having a polymerizable carbon-carbon double bond introduced into an acrylic resin is used. The use of an acrylic resin makes it easy to adjust the storage modulus and tensile modulus of the pressure-sensitive adhesive layer, and also allows for the production of a pressure-sensitive adhesive sheet with an excellent balance between adhesive strength and releasability. Furthermore, contamination of semiconductor wafers by components derived from the pressure-sensitive adhesive can be reduced.

[0031] C-1. Base polymer Any suitable polymer can be used as the base polymer. The base polymer can be obtained by polymerizing any suitable monomer composition. As described above, a (meth)acrylic polymer is preferably used as the base polymer. In this specification, "(meth)acrylic" refers to acrylic and / or methacrylic.

[0032] The monomer composition used in the polymerization of the base polymer may contain any appropriate monomer. The monomer component preferably contains a (meth)acrylic monomer having a side chain with 8 or more carbon atoms. Any appropriate monomer can be used as the (meth)acrylic monomer having a side chain with 8 or more carbon atoms. Examples include 2-ethylhexyl acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and dodecyl (meth)acrylate. The (meth)acrylic monomer having a side chain with 8 or more carbon atoms may be used alone or in combination of two or more.

[0033] The content of the (meth)acrylic monomer having a side chain containing 8 or more carbon atoms contained in the monomer composition can be set to any appropriate value. The content of the (meth)acrylic monomer having a side chain containing 8 or more carbon atoms is preferably 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, of the total of 100 mol% of all monomer components. The content of the (meth)acrylic monomer having a side chain containing 8 or more carbon atoms is, for example, less than 90 mol%. When the content of the (meth)acrylic monomer having a side chain containing 8 or more carbon atoms is within the above range, the surface energy X can be adjusted to an appropriate value, and an adhesive tape for semiconductor wafer processing can be provided that has excellent embedding properties for unevenness and minimizes adhesive residue on the semiconductor wafer surface.

[0034] The monomer composition may contain any other appropriate monomer in addition to the (meth)acrylic monomer having 8 or more carbon atoms. Examples of the other monomer include a monomer having a side chain with 2 or less carbon atoms and a highly polar monomer. Any appropriate monomer can be used as the monomer having a side chain with 2 or less carbon atoms. Examples include methyl (meth)acrylate and ethyl (meth)acrylate. Only one type of monomer having a side chain with 2 or less carbon atoms may be used, or two or more types may be used in combination.

[0035] Any appropriate monomer can be used as the highly polar monomer. Examples include hydroxyl group-containing monomers, carboxyl group-containing monomers, and nitrogen-containing monomers. The highly polar monomer may have two or more polar groups (for example, a hydroxyl group and a nitrogen-containing group). The highly polar monomer is preferably a highly polar monomer having a side chain with 4 or less carbon atoms, more preferably a hydroxyl group-containing monomer having a side chain with 4 or less carbon atoms. Only one type of highly polar monomer may be used, or two or more types may be used in combination.

[0036] Any appropriate monomer can be used as the hydroxyl group-containing monomer. Specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and N-(2-hydroxyethyl)acrylamide. Only one type of hydroxyl group-containing monomer may be used, or two or more types may be used in combination.

[0037] Any appropriate monomer can be used as the carboxyl group-containing monomer. Specific examples include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The carboxyl group-containing monomer may be used alone or in combination of two or more.

[0038] Any appropriate nitrogen-containing monomer can be used. Specific examples include N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, (meth)acryloylmorpholine, N-vinylcarboxylic acid amides, N-vinylcaprolactam, N-(2-hydroxyethyl)acrylamide, and N,N-dimethylacrylamide. The nitrogen-containing monomer may be used alone or in combination of two or more.

[0039] The content (total content) of at least one monomer selected from the group consisting of a monomer having a side chain with two or less carbon atoms and a highly polar monomer in the monomer composition can be set to any appropriate value. The content (total content) of at least one monomer selected from the group consisting of a monomer having a side chain with two or less carbon atoms and a highly polar monomer contained in the monomer composition is preferably 39 mol % or less, more preferably 30 mol % or less, and even more preferably 20 mol % or less, based on 100 mol % of all monomer components. When the content (total content) of at least one monomer selected from the group consisting of a monomer having a side chain with two or less carbon atoms and a highly polar monomer is within the above range, the surface energy X can be adjusted to an appropriate value, and an adhesive tape for semiconductor wafer processing can be provided that has excellent embedding properties for irregularities and minimizes adhesive residue on the semiconductor wafer surface.

[0040] In one embodiment, a hydroxyl group-containing monomer is preferably used as the highly polar monomer. By using a hydroxyl group-containing monomer, a (meth)acrylic polymer having a polymerizable carbon-carbon double bond introduced into a side chain and / or terminal can be obtained by further reacting the hydroxyl group-containing monomer with a compound having an isocyanate group, as described below. The content of the hydroxyl group-containing monomer is preferably 39 mol % or less, more preferably 10 mol % to 39 mol %, of the total of all monomer components (100 mol %). When the content of the hydroxyl group-containing monomer is within the above range, adhesive residue on the adherend (semiconductor wafer surface) can be further suppressed upon peeling of the adhesive tape for semiconductor wafer processing after irradiation with active energy rays.

[0041] The monomer composition may further contain any other appropriate monomers. Examples of the other monomers include acid anhydride monomers such as maleic anhydride and itaconic anhydride; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and functional group-containing monomers such as phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate.

[0042] As described above, a polymer having a polymerizable carbon-carbon double bond introduced into a side chain and / or terminal may be used as the base polymer. A polymer having a polymerizable carbon-carbon double bond introduced into a side chain and / or terminal may be obtained by any appropriate method. For example, it may be obtained by reacting (e.g., condensation reaction, addition reaction) a resin obtained by any appropriate polymerization method with a compound having a polymerizable carbon-carbon double bond. Specifically, when an acrylic resin is used, a (meth)acrylic polymer (copolymer) having structural units derived from a monomer having any appropriate functional group is polymerized in any appropriate solvent, and then the functional group of the (meth)acrylic polymer is reacted with a compound having a polymerizable carbon-carbon double bond that can react with the functional group to obtain a (meth)acrylic polymer having an introduced polymerizable carbon-carbon double bond. The amount of the compound having a polymerizable carbon-carbon double bond to be reacted is preferably 4 to 30 parts by weight, more preferably 4 to 20 parts by weight, per 100 parts by weight of the polymer. Any suitable solvent can be used, and examples thereof include various organic solvents such as ethyl acetate, methyl ethyl ketone, and toluene.

[0043] When reacting a (meth)acrylic polymer with a compound having a polymerizable carbon-carbon double bond as described above, it is preferable that the resin and the compound having a polymerizable carbon-carbon double bond each have a functional group capable of reacting with each other. Examples of functional group combinations include a carboxyl group / epoxy group, a carboxyl group / aziridine group, and a hydroxyl group / isocyanate group. Among these functional group combinations, a combination of a hydroxyl group and an isocyanate group is preferred because it is easy to track the reaction.

[0044] Examples of compounds having a polymerizable carbon-carbon double bond include 2-isocyanatoethyl methacrylate, methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate.

[0045] The weight-average molecular weight of the (meth)acrylic polymer is preferably 100,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, and particularly preferably 250,000 to 1,000,000. Within this range, bleeding of low molecular weight components can be prevented, and a low-contamination adhesive sheet for semiconductor wafer processing can be obtained. The weight-average molecular weight can be determined by gel permeation chromatography (solvent: tetrahydrofuran, polystyrene equivalent).

[0046] The gel fraction of the (meth)acrylic polymer is preferably 75% or more, more preferably 80% or more, and even more preferably 82% or more. The gel fraction of the (meth)acrylic polymer is preferably 90% or less. When the gel fraction is within the above range, an adhesive tape for semiconductor wafer processing can be provided that has excellent irregularity filling ability and minimizes adhesive residue on the semiconductor wafer surface.

[0047] The (meth)acrylic polymer can be obtained by polymerizing the above-mentioned monomer composition by any appropriate method. Examples include solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization. The reaction temperature and reaction time can be set to any appropriate value depending on the weight-average molecular weight, gel fraction, and type of monomer used of the resulting (meth)acrylic polymer. Furthermore, by adjusting reaction conditions such as the reaction temperature and reaction time and / or the solids concentration of the monomer composition used, the weight-average molecular weight and / or gel fraction of the resulting (meth)acrylic polymer can be adjusted to any value.

[0048] C-2. Photopolymerization initiator The active energy ray-curable adhesive forming the adhesive layer preferably further contains a photopolymerization initiator. Any appropriate initiator can be used as the photopolymerization initiator. Examples of the photopolymerization initiator include acylphosphine oxide photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate 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; methoxyacetophenone, Acetophenone compounds such as 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; ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; 1-phenone-1,1-propanedione-2-( Photoactive oxime compounds such as 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 acylphosphonate, 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 and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl-2-methylpropane-1 can be used. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0049] As the photopolymerization initiator, commercially available products may be used, for example, trade names of Omnirad 127D, Omnirad 651, Omnirad 369E, and Omnirad 819 manufactured by IGM Resins.

[0050] The photopolymerization initiator is used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of the base polymer. If the content of the photopolymerization initiator is less than 0.5 parts by weight, there is a risk that the adhesive will not cure sufficiently when irradiated with ultraviolet light. If the content of the photopolymerization initiator exceeds 10 parts by weight, there is a risk that the storage stability of the adhesive will decrease.

[0051] C-3. Additives The PSA may contain any suitable additives as needed, such as crosslinkers, 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.

[0052] In one embodiment, the pressure-sensitive adhesive further contains 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 is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 5 parts by weight, and even more preferably 0.025 to 0.5 parts by weight, relative to 100 parts by weight of the base polymer contained in the pressure-sensitive adhesive. The flexibility of the pressure-sensitive adhesive layer can be controlled by the content of the crosslinking agent. If the content of the crosslinking agent is less than 0.01 part by weight, the pressure-sensitive adhesive may become a sol, making it impossible to form a pressure-sensitive adhesive layer. If the content of the crosslinking agent exceeds 10 parts by weight, adhesion to the semiconductor wafer may decrease, and the semiconductor wafer may not be sufficiently protected.

[0053] 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 preferably, a crosslinking agent having three or more isocyanate groups is used. When an isocyanate-based crosslinking agent is used as the crosslinking agent and the content of the crosslinking agent is within the above range, a pressure-sensitive adhesive layer can be formed that has excellent releasability and significantly less adhesive residue even after heating.

[0054] 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 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 4 μm to 30 μm. If the thickness of the pressure-sensitive adhesive layer is within the above range, it can exert sufficient adhesive strength to the semiconductor wafer.

[0055] The pressure-sensitive adhesive layer may have any appropriate adhesive strength. The adhesive strength of the pressure-sensitive adhesive layer to a silicon wafer before UV irradiation is preferably 0.50 N / 20 mm to 30 N / 20 mm, more preferably 2 N / 20 mm to 25 N / 20 mm, and even more preferably 5 N / 20 mm to 25 N / 20 mm. In this specification, the adhesive strength of the pressure-sensitive adhesive layer refers to the value measured by cutting a pressure-sensitive adhesive tape for semiconductor wafer processing to a width of 20 mm and a length of 80 mm, pressing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape for semiconductor wafer processing to the mirror surface of a silicon mirror wafer by rolling a 2 kg roller back and forth once in an atmosphere of 23°C, leaving it at 23°C for 30 minutes, and then performing a 180° peel test under conditions of 23°C, 50% RH, and a pulling rate of 300 mm / min.

[0056] The adhesive strength of the adhesive layer to a silicon wafer after ultraviolet irradiation is preferably 0.001 N / 20 mm to 1.000 N / 20 mm, more preferably 0.005 N / 20 mm to 0.850 N / 20 mm, and even more preferably 0.03 N / 20 mm to 0.40 N / 20 mm. The adhesive strength after ultraviolet irradiation is measured by cutting the adhesive tape for semiconductor wafer processing to a width of 20 mm and a length of 80 mm, pressing the adhesive layer onto the mirror surface of a silicon mirror wafer by moving a 2 kg roller back and forth once in an atmosphere at 23°C, leaving it at 23°C for 30 minutes, and then irradiating the adhesive tape with ultraviolet (UV) light at an integrated light intensity of 1000 mJ / cm. 2This refers to the value measured by irradiating the substrate side of the adhesive tape for semiconductor wafer processing with light so that the optical intensity is 365 nm (equivalent to 365 nm), and then conducting a 180° peel test under conditions of 23°C, 50% RH, and a pulling speed of 300 mm / min.

[0057] D. middle class In one embodiment, the adhesive tape for semiconductor wafer processing preferably further comprises an intermediate layer. When the adhesive tape for semiconductor wafer processing further comprises an intermediate layer, the adhesive tape can further improve its ability to embed the irregularities when the adherend surface has irregularities.

[0058] The intermediate layer may be formed of any suitable material. The intermediate layer may be formed of any suitable resin, such as an acrylic resin, a polyethylene resin, an ethylene-vinyl alcohol copolymer, an ethylene vinyl acetate resin, or an ethylene methyl methacrylate resin, or an adhesive such as an acrylic adhesive. Preferably, an acrylic adhesive is used. An acrylic adhesive typically contains an acrylic-based polymer.

[0059] In one embodiment, the intermediate layer contains a photopolymerization initiator but does not contain a UV-curable component. That is, although the intermediate layer contains a photopolymerization initiator, it does not cure upon UV irradiation. Therefore, the intermediate layer can maintain its flexibility before and after UV irradiation. Furthermore, if the intermediate layer contains a photopolymerization initiator, the photopolymerization initiator contained in the pressure-sensitive adhesive layer can migrate to the intermediate layer, thereby preventing the content of the photopolymerization initiator contained in the pressure-sensitive adhesive layer from decreasing over time. Therefore, after UV irradiation, the pressure-sensitive adhesive tape for semiconductor wafer processing can exhibit excellent easy peelability. In this specification, the UV-curable component refers to a component that can be crosslinked and undergo cure shrinkage upon UV irradiation. Specific examples include polymers having the above-mentioned carbon-unsaturated double bonds in their side chains or terminals.

[0060] 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 pressure-sensitive adhesive layer. Preferably, the intermediate layer contains the same photopolymerization initiator as the pressure-sensitive adhesive layer. If the intermediate layer and the pressure-sensitive adhesive layer contain the same photopolymerization initiator, migration of the photopolymerization initiator from the pressure-sensitive adhesive layer to the intermediate layer can be further suppressed. As the photopolymerization initiator, the photopolymerization initiators exemplified for the pressure-sensitive adhesive composition above can be used. A single photopolymerization initiator may be used, or two or more types may be used in combination. The content of the photopolymerization initiator in the intermediate layer is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of the polymer constituents in the intermediate layer-forming composition. When the content of the photopolymerization initiator in the intermediate layer is within the above range, a pressure-sensitive adhesive tape for semiconductor wafer processing having excellent easy peelability after ultraviolet irradiation can be obtained. In one embodiment, the photopolymerization initiator is used in an amount equal to that of the composition forming the pressure-sensitive adhesive layer.

[0061] In one embodiment, the composition for forming an intermediate layer further includes 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, and amine-based crosslinking agents. When the composition for forming an intermediate layer includes 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 constituents in the composition for forming an intermediate layer.

[0062] The intermediate layer-forming composition may further contain any appropriate additives as needed, such as an active energy ray polymerization accelerator, a radical scavenger, a tackifier, a plasticizer (e.g., a trimellitic acid ester-based plasticizer, a pyromellitic acid ester-based plasticizer, etc.), a pigment, a dye, a filler, an antioxidant, a conductive material, an antistatic agent, an ultraviolet absorber, a light stabilizer, a release agent, a softener, a surfactant, a flame retardant, and an antioxidant.

[0063] The thickness of the intermediate layer can be set to any appropriate value. The thickness of the intermediate layer is preferably 10 μm to 300 μm, more preferably 30 μm to 200 μm, even more preferably 50 μm to 150 μm, and particularly preferably 90 μm to 150 μm. When the thickness of the intermediate layer is within the above range, an adhesive tape for semiconductor wafer processing that can well fill uneven surfaces can be obtained.

[0064] E. Manufacturing method of adhesive tape for semiconductor wafer processing The adhesive tape for semiconductor wafer processing can be produced by any appropriate method. In one embodiment, the adhesive tape for semiconductor wafer processing can be produced, for example, by forming an optional intermediate layer on a substrate, and then forming an adhesive layer on the substrate or the optional intermediate layer. The adhesive layer and intermediate layer may be formed by coating the composition for forming the adhesive layer and the composition for forming the intermediate layer on the substrate or intermediate layer, respectively, or by forming the layers on any appropriate release liner and then transferring them. Various coating methods can be used, including 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 can be used in which the adhesive layer or intermediate layer is separately formed on a release liner and then laminated to the substrate.

[0065] F. Applications of adhesive tape for semiconductor wafer processing The adhesive tape for semiconductor wafer processing according to an embodiment of the present invention can be suitably used in semiconductor element manufacturing processes. The adhesive tape for semiconductor wafer processing according to an embodiment of the present invention can be suitably used as a backgrinding tape. A backgrinding tape is required to properly hold a silicon wafer during backgrinding, and to have light releasability that allows it to be peeled off without damaging the ground wafer and leaving no adhesive residue when peeled off. The adhesive tape for semiconductor wafer processing according to an embodiment of the present invention has excellent irregularity embedding properties and can suppress adhesive residue on the semiconductor wafer surface. Therefore, the adhesive tape for semiconductor wafer processing according to an embodiment of the present invention can be suitably used as a backgrinding tape. [Example]

[0066] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are by weight unless otherwise specified.

[0067] [Example 1] 1. Preparation of Intermediate Layer-Forming Composition 50 parts by weight of butyl acrylate (BA), 50 parts by weight of ethyl acrylate (EA), 5 parts by weight of acrylic acid (AA), and 0.1 parts by weight of azobisisobutyronitrile (AIBN) were polymerized in toluene under a nitrogen atmosphere at 60°C for 6 hours to obtain a polymer solution containing a (meth)acrylic polymer with a weight-average molecular weight of 650,000. 100 parts by weight of the solid content of the obtained polymer solution was mixed with 1 part by weight of a polyisocyanate compound (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101A") and 1 part by weight of a photopolymerization initiator (manufactured by IGM RESINS, product name: Omnirad 127D) to obtain an intermediate layer-forming composition containing toluene (solid content concentration 23%).

[0068] 2. Preparation of Pressure-Sensitive Adhesive Composition The monomer components used were 89 wt% 2-ethylhexyl acrylate (2EHA) and 11 wt% 2-hydroxyethyl acrylate (HEA) (manufactured by Toagosei Co., Ltd., trade name: Aclix® HEA). A monomer composition (solids concentration 32%) was prepared by mixing 0.15 wt% of a polymerization initiator (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: 2,2'-azobis(isobutyronitrile) (AIBN)) with ethyl acetate as the total weight of the monomer components. The resulting monomer composition was placed in a 1 L round-bottom separable flask and placed in a polymerization laboratory equipped with a separable cover, separatory funnel, thermometer, nitrogen inlet tube, Liebig condenser, vacuum seal, stirring rod, and stirring blade. The mixture was then purged with nitrogen at room temperature for 1 hour while stirring. Thereafter, the mixture was stirred under a nitrogen flow and maintained at 67°C for 5 hours to carry out solution polymerization, and then the temperature was raised to 76°C and maintained at 76°C for 2 hours to obtain a polymer solution. The resulting polymer solution was cooled to below 35°C and stirred for 15 minutes while oxygen was introduced into the flask. Then, 2-methacryloyloxyethyl isocyanate (MOI) (manufactured by Resonac, product name "Karenz MOI") was added to the solution to a molar ratio of 80% based on the amount of HEA added. Furthermore, 0.03% by weight of dibutyltin dilaurate was added as a reaction catalyst based on the amount of MOI added. The resulting mixture was then subjected to an addition reaction (urethanization reaction) in an air stream at 50°C for 12 hours to obtain an ultraviolet (UV)-curable acrylic copolymer. Next, 2 parts by weight of a photopolymerization initiator (manufactured by IGM RESIN, product name "Omnirad127D"), 1 part by weight of a polyisocyanate compound (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101A"), and 0.01 part by weight of an antioxidant (manufactured by BASF Japan, product name "Irganox1010") were added to 100 parts by weight of the UV-curable acrylic copolymer to prepare a pressure-sensitive adhesive composition.

[0069] 3. Tape Preparation The intermediate layer-forming composition obtained in 1. was applied to the silicone-treated surface of a 38 μm-thick polyester release liner (manufactured by Mitsubishi Chemical Corporation, trade name "Diafoil (registered trademark)") and heated at 120°C for 120 seconds to remove the solvent, forming an intermediate layer 1 with a thickness of 50 μm. Next, a 50 μm-thick PET film (manufactured by Toray Industries, trade name "Lumirror (registered trademark)") was laminated to the surface of the formed intermediate layer 1. Separately, the intermediate layer-forming composition was applied to the silicone-treated surface of a 38 μm-thick polyester release liner and heated at 120°C for 120 seconds to remove the solvent, forming an intermediate layer 2 with a thickness of 50 μm. The release liner was peeled from intermediate layer 1, and intermediate layer 2 was laminated to the surface of intermediate layer 1 from which the release liner had been peeled, yielding a laminate of the substrate and intermediate layer (intermediate layer 1 / intermediate layer 2). Separately, the adhesive composition obtained in 2. was applied to the silicone-treated surface of a 75 μm thick polyester release liner, and heated at 120°C for 120 seconds to remove the solvent, forming an adhesive layer 20 μm thick. Next, the release liner was peeled off from intermediate layer 2, and the adhesive layer was attached and transferred to the surface of the intermediate layer from which the release liner had been peeled off.Then, the adhesive tape was stored at 50°C for 72 hours, obtaining an adhesive tape having a substrate / intermediate layer (intermediate layer 1 / intermediate layer 2) / adhesive layer in that order.

[0070] [Examples 2 to 6] Pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the monomer compositions, polymerization conditions for the monomers, and the composition of the pressure-sensitive adhesive composition were changed as shown in Table 1.

[0071] (Comparative Examples 1 to 3) Pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the monomer compositions, polymerization conditions for the monomers, and the composition of the pressure-sensitive adhesive composition were changed as shown in Table 1.

[0072] [Table 1]

[0073] <Evaluation> The pressure-sensitive adhesive tapes obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Table 1. 1. Weight average molecular weight Mw measurement Approximately 0.2 g of sample was obtained from the obtained UV-curable acrylic copolymer. The collected sample was dissolved in tetrahydrofuran (THF) to prepare a THF solution with a solid content of 0.2 wt % and left overnight. The THF solution left overnight was filtered through a membrane filter with a pore size of 0.45 μm, and the obtained filtrate was used as the measurement sample. The weight average molecular weight Mw of the measurement sample was measured using an HLC-8220GPC manufactured by Tosoh Corporation as an analytical device under the following measurement conditions. Columns: One TSKgel quadcolumn SuperHZ-L (hereinafter referred to as the first column) manufactured by Tosoh Corporation, and two TSKgel SuperHZM-M (hereinafter referred to as the second column) manufactured by Tosoh Corporation. Each column was arranged in an analytical device such that two second columns were connected in series downstream of the first column, and the eluent flowed into the first column side. Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: Sample pump flow rate 0.3 mL / min, reference pump flow rate 1.0 mL / min ·Injection volume: 100μL Detector: Refractive index detector (RI) To obtain a molecular weight distribution curve (differential molecular weight distribution curve) based on the measurement results of the measurement sample, each standard polystyrene manufactured by Tosoh Corporation was weighed out to the blend weight shown in Table 2 below, and each weighed standard polystyrene was dissolved in 100 mL of THF to obtain standard polystyrene solution STD1 and standard polystyrene solution STD2. These were also subjected to GPC measurement in the same manner. [Table 2]

[0074] 2. Gel fraction A sample of approximately 0.2 g was collected from the pressure-sensitive adhesive composition before curing by UV irradiation. The sample was then wrapped in a mesh sheet (manufactured by Nitto Denko Corporation, product name: NTF1122, film thickness 80 μm, average pore size 0.2 μm) and immersed in approximately 30 mL of ethyl acetate at room temperature for one week. The mesh sheet was then removed from the ethyl acetate, and the ethyl acetate-insoluble matter contained in the mesh sheet was recovered. The recovered ethyl acetate-insoluble matter was dried at 130°C under normal pressure for approximately two hours, and the ethyl acetate-insoluble matter was weighed. The weight ratio of the gel component was calculated using the following formula, and the gel fraction was calculated. Gel fraction (%) = [(weighed amount of ethyl acetate insoluble matter (g)) / weight of sample obtained (g)] × 100

[0075] 3.Storage modulus The pressure-sensitive adhesive compositions used in the examples and comparative examples were laminated without bubbles to a thickness of approximately 0.8 mm to 1.0 mm to prepare samples. The storage modulus G' at 25°C was measured under the following conditions using a viscoelasticity measuring device (manufactured by TA Instruments, product name "ARES-G2"). Mode: Torsion mode Plate diameter: 7.9mm Distortion: 0.1% (-50℃) Frequency: 1Hz Measurement range: -50℃~150℃

[0076] 4. Contact angle and surface free energy The surface free energy of the adhesive layer of the adhesive tapes obtained in the Examples and Comparative Examples was measured by the following method. Water or methylene iodide was dropped onto the surface of the adhesive layer of the adhesive tape, and the contact angle was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name: CA-X). This measurement value and the surface free energy value (known from literature) of the contact angle measurement liquid (water or methylene iodide) were substituted into the following equation (I) derived from Young's equation and the extended Fowkes equation, and the two resulting equations were solved as simultaneous linear equations to calculate the surface free energy value. The surface free energy γS of a solid was calculated as γS d and γS v It is the harmony of. (1+cosθ)γL =2√(γS d γL d )+2√(γ S v gamma L v )···(I) The symbols in the formula are as follows: θ: contact angle gamma L : Contact angle measurement Surface free energy of liquid gamma L d :r L Dispersion force components in gamma L v :r L Polar force component in gamma S d : Dispersion force component in the surface free energy of a solid gamma S v : Polar force component in the surface free energy of a solid

[0077] 5. Peak and integral values The tack test of the pressure-sensitive adhesive layer was carried out by the probe tack method using a probe tack tester (product name "TAC-II") manufactured by Rhesca Co., Ltd. under the following measurement conditions. (Measurement conditions) Probe diameter: 5mmΦ Contact speed: 120mm / min Load: 10gf Contact time: 1 second Peeling speed: 600 mm / min Specifically, the substrate surface of each adhesive tape was attached to a glass slide using double-sided tape (Nitto Denko Corporation, product name "No. 5000NS"), and the adhesive tape was fixed to the glass slide. Next, a probe with a probe diameter of 5 mm was pressed against the adhesive layer of the adhesive tape at a contact speed of 120 mm / min, applying a load of 10 gf and maintaining contact for 1 second. The probe was then pulled up at a peeling speed of 600 mm / min, and the peak value (Peak Value [gf]) at the time of peeling was calculated as the tack value TA (gf), and the peak area (Integral [gf·sec]) was calculated as the integral value IA (gf·sec).

[0078] 6. Embeddability The adhesive tapes obtained in the examples and comparative examples were cut into 230 cm x 400 cm pieces. The cut adhesive tapes were attached to wafers (8 inches, bump height 75 μm, diameter 90 μm, pitch 200 μm) using a tape attachment device (manufactured by Nitto Seiki Co., Ltd., product name: DR-3000III). The attachment was performed under the following conditions: Roller pressure: 0.27MPa Roller speed: 20mm / sec Table temperature: Room temperature (RT) After the application, the state of attachment of the adhesive tape and the wafer was observed using a laser microscope (magnification: 100 times). In addition, the adhesive tape and wafer were photographed from the adhesive tape side with the adhesive tape facing up, and the images were binarized (8-bit grayscale, brightness: 0–255, threshold: 114) using image analysis software (Image J (free software)). Five bumps were then randomly selected from the wafer, and the number of dots used to represent each bump was measured. The image of the bump alone without the tape attached had 220 dots, and the closer the dot count measured with the adhesive tape attached to 220, the better the embedding. Note that when adhesive tape is attached to a semiconductor wafer with bumps, the dot count is usually around 820. An average dot count of 700 or less for any five bumps was evaluated as ◎ (very good), 701–820 as 〇 (good), and over 820 as △ (room for improvement).

[0079] 7. Glue residue A silicon wafer was ground under the following conditions to prepare a wafer with an exposed active surface. Wafer used: 8-inch silicon mirror wafer Back grinder: DFG8560 (DISCO) Z1 Wheel: Spec "GF01-SD360-VS-100", Size "300 x 4W x 4T" Z2 Wheel: Spec: "BGT-270 IF-01-1-4 / 6-B-K09", Size: "300 x 5T x 3W" Thickness after grinding: 500 μm Grinding water: Pure water Three sheets of adhesive tape (product name "BT-315") manufactured by Nitto Denko Corporation were stacked on the prepared wafer to create a step. Then, using a tape application device (manufactured by Nitto Seiki Co., Ltd., product name "DR-3000III"), the tape was applied across the step. The wafer was then heated at 60°C for 24 hours. After heating, a UV irradiator (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") was used to irradiate the wafer from the substrate side with a high-pressure mercury lamp at 1000 mJ / cm. 2 After irradiation, the tape was peeled off at a peel angle of 180° and a peel speed of 300 mm / min using a tensile tester, and adhesive residue was visually confirmed using an optical microscope. The lamination conditions are as follows: Pressure: 0.4 MPa Speed: 5mm / sec Table temperature: Room temperature (RT) Periphery table height: 400 μm When almost no adhesive residue was visible on the wafer surface after peeling off the adhesive tape, it was evaluated as ⊚ (very good); when adhesive residue was visible in lines when observed under a microscope, it was evaluated as ◯ (good); and when adhesive residue could be confirmed without using a microscope, it was evaluated as △ (room for improvement).

[0080] The adhesive tapes of the examples of the present invention were excellent in surface embedding ability for the surface of a semiconductor wafer having irregularities, and also suppressed adhesive residue. [Industrial Applicability]

[0081] The adhesive tape for semiconductor wafer processing according to the embodiment of the present invention can be suitably used for semiconductor wafer processing applications, for example, as a backgrind tape for semiconductor wafer processing. [Explanation of symbols]

[0082] 10 Base material 20 adhesive layer 30 Middle Class 100 Adhesive tape for semiconductor wafer processing

Claims

1. An adhesive tape for semiconductor wafer processing comprising a substrate and an adhesive layer formed of an active energy ray-curable adhesive, The surface free energy X (mN / m) of the pressure-sensitive adhesive layer and the tack value T of the pressure-sensitive adhesive layer measured by a probe tack method Ａ (gf) and the integral value I Ａ (gf sec) and the quotient Y(I Ａ / T Ａ ) satisfies the relationship of formula (1). Y>0.01X-0.21 (1)

2. the active energy ray-curable pressure-sensitive adhesive contains a (meth)acrylic polymer, 2. The adhesive tape for semiconductor wafer processing according to claim 1, wherein the (meth)acrylic polymer is a polymer obtained by polymerizing a monomer composition containing 60 mol % or more of a (meth)acrylic monomer having a side chain containing 8 or more carbon atoms.

3. 3. The adhesive tape for semiconductor wafer processing according to claim 2, wherein the monomer composition contains 39 mol% or less of at least one selected from the group consisting of monomers having a side chain with 2 or less carbon atoms and highly polar monomers.

4. 4. The adhesive tape for semiconductor wafer processing according to claim 3, wherein the highly polar monomer is a hydroxyl group-containing monomer having a side chain containing 4 or less carbon atoms.

5. 5. The adhesive tape for processing semiconductor wafers according to claim 4, wherein the monomer composition contains 10 mol % to 39 mol % of the hydroxyl group-containing monomer having a side chain containing 4 or less carbon atoms.

6. The adhesive tape for semiconductor wafer processing according to claim 1, further comprising an intermediate layer.

7. 7. The adhesive tape for semiconductor wafer processing according to claim 1, which is a backgrinding tape.

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