Backgrind tape

Abstract

To provide a back grinding tape capable of achieving both excellent unevenness fillability and cutting property.SOLUTION: According an embodiment of the present invention, a back grinding tape includes a base material, an intermediate layer, and an adhesive layer. The nanoindentation hardness (25°C) of the intermediate layer is 0.001 MPa to 0.200 MPa, the nanoindentation hardness (25°C) of the adhesive layer is 0.001 MPa to 0.080 MPa, the thickness of at least one of the intermediate layer and the adhesive layer is 50 μm or more, and the unloading curve displacement magnitude of the layer whose thickness is 50 μm or more is 8000 μm or less.SELECTED DRAWING: Figure 1

Description

[[Technical Field]]

[0001] The present invention relates to a backgrinding tape. [[Background Art]]

[0002] Semiconductor wafers are used in various applications such as personal computers, smartphones, and automobiles. In the processing steps of semiconductor wafers, adhesive tapes are used to protect the surface during processing. In recent years, miniaturization and higher functionality of large-scale integrated circuits (LSI) have advanced, leading to increased complexity of the surface structure of wafers. Specifically, the three-dimensional structure on the wafer surface has become more complex due to solder bumps and the like. Therefore, adhesive tapes used in semiconductor processing steps are required to have good embedding properties for unevenness on the wafer surface and high adhesiveness. Adhesive tapes used in the backgrinding step for semiconductor wafers are required to appropriately hold the semiconductor wafer during the backgrinding step and be easily peeled off after the backgrinding step. Since the thickness of a semiconductor wafer subjected to a backgrinding step becomes remarkably thin, backgrinding tapes are required to be peelable without adhesive residue and damage to the semiconductor wafer.

[0003] In recent years, along with the miniaturization and thinning of various products, the thinning of semiconductor wafers has been progressing. For thinly processed wafers, if the adhesive force of the adhesive tape is too high, the wafer may be damaged when the adhesive tape is peeled off. Therefore, adhesive tapes using ultraviolet-curable pressure-sensitive adhesives have been proposed to prevent adhesive residue on the adherend and damage to the wafer during peeling (for example, Patent Documents 1 and 2). Additionally, as an adhesive tape suitable for processing semiconductor wafers having an uneven structure such as bumps, adhesive tapes excellent in embedding properties for unevenness have been proposed (for example, Patent Document 3). However, adhesive tapes excellent in embedding properties for unevenness may cause stringing of the adhesive layer in the cutting step after tape application, which may damage the semiconductor wafer during the backgrinding step and the peeling step after processing. [[Prior Art Documents]] [[Patent Documents]]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-017758 [Patent Document 2] Japanese Patent Publication No. 2013-213075 [Patent Document 3] Japanese Patent Publication No. 2022-121480 [Overview of the project] [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 can achieve both excellent unevenness embedding and cutability. [Means for solving the problem]

[0006] 1. The backgrind tape according to an embodiment of the present invention comprises a base material, an intermediate layer, and an adhesive layer, wherein the nanoindentation hardness (25°C) of the intermediate layer is 0.001 MPa to 0.200 MPa, and the nanoindentation hardness (25°C) of the adhesive layer is 0.001 MPa to 0.080 MPa. The thickness of at least one of the intermediate layer and the adhesive layer is 50 μm or more, and the unloading curve displacement of the layer with a thickness of 50 μm or more is 8000 μm or less. 2. In the backgrind tape described in item 1 above, the product of the nanoindentation hardness (MPa) and thickness (μm) of the intermediate layer may be 0.050 to 15.000. 3. In the backgrind tape described in 1 or 2 above, the product of the nanoindentation hardness (MPa) and thickness (μm) of the adhesive layer may be 0.001 to 1.000. 4. In the backgrind tape described in any of items 1 to 3 above, the thickness of the adhesive layer may be 1 μm to 50 μm. 5. In the backgrind tape described in any of items 1 to 4 above, the intermediate layer may contain a (meth)acrylic polymer obtained by polymerizing a monomer composition containing a monomer having a glass transition temperature of 80°C or higher. 6. In the backgrind tape described in item 5 above, the intermediate layer may contain a (meth)acrylic polymer obtained by polymerizing a monomer composition containing 5% to 50% by weight of a monomer having a glass transition temperature of 80°C or higher. 7. In the backgrind tape described in any of items 1 to 6 above, the adhesive layer may be formed of an ultraviolet-curing adhesive. 8. In the backgrind tape described in any of items 1 to 7 above, the adhesive layer may be formed of an adhesive containing a polyfunctional acrylate. 9. The backgrind tape described in any of items 1 to 8 above may be bonded to a semiconductor wafer on which bumps are formed, and the height of the bumps (μm) and the sum of the thickness of the adhesive layer (μm) and the thickness of the intermediate layer (μm) may satisfy the relationship: bump height (μm) < thickness of adhesive layer (μm) + thickness of intermediate layer (μm). 10. The backgrind tape described in any of items 1 to 9 above may be bonded to a semiconductor wafer on which bumps are formed, and the height of the bumps (μm) and the thickness of the intermediate layer (μm) may satisfy the relationship: bump height (μm) < thickness of the intermediate layer (μm). [Effects of the Invention]

[0007] According to embodiments of the present invention, a backgrind tape capable of both excellent unevenness embedding and cutability can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of a backgrind tape according to an embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view of the backgrind tape and indenter when performing nanoindenter measurement of the intermediate layer. [Figure 3] This is a schematic cross-sectional view of the backgrind tape and indenter when performing nanoindenter measurement of the adhesive layer. [Modes for carrying out the invention]

[0009] A. Overall structure of the backgrind tape Figure 1 is a schematic cross-sectional view of a backgrind tape according to an embodiment of the present invention. The backgrind tape 100 according to an embodiment of the present invention comprises a base material 10, an intermediate layer 20, and an adhesive layer 30. Practically, a release liner can be temporarily attached to the adhesive layer 30 in a peelable manner until use. The intermediate layer 20 can be formed from any suitable resin or any suitable adhesive. The nanoindentation hardness (25°C) of the intermediate layer 20 is 0.001 MPa to 0.200 MPa. The nanoindentation hardness (25°C) of the adhesive layer 30 is 0.001 MPa to 0.080 MPa. At least one of the intermediate layer 20 and the adhesive layer 30 has a thickness of 50 μm or more. Furthermore, the layer with a thickness of 50 μm or more has an unloading curve displacement of 8000 μm or less. Backgrind tapes used for processing semiconductor wafers having bumps and other irregularities are required to be able to fill in the irregularities on the surface of the semiconductor wafer. On the other hand, backgrind tapes with excellent embedding properties have poor cutability, and stringing may occur in the adhesive layer and / or intermediate layer during the cutting process of the backgrind tape. The stringed adhesive or intermediate layer forming composition can adhere to the semiconductor wafer. As a result, the thinly ground semiconductor wafer may be damaged when the backgrind tape is peeled off. Thus, it is difficult to achieve both excellent embedding properties and good cutability. The inventors have found that a backgrind tape having an adhesive layer and an intermediate layer in which the nanoindentation hardness and unloading curve displacement measured in the backgrind tape state are within a specific range can achieve both excellent embedding properties and good cutability (e.g., suppression of stringing in the adhesive layer and intermediate layer), and have completed the present invention. Note that if the thickness is less than 50 μm, it can usually be cut without stringing using a cutter used in the tape cutting process.

[0010] The above nanoindentation hardness and unloading curve displacement can be obtained by nanoindentation measurement. Measurement using a nanoindenter is performed by controlling the load applied by the indenter and measuring the displacement (indenter indentation depth). A load-displacement curve can be created from the measurement results, and properties such as nanoindentation hardness can be determined. The load-displacement curve is generally created with the horizontal axis representing displacement (indentation depth) and the vertical axis representing load (force required for indentation). For example, in the case of adhesive layers and intermediate layers, when the indenter is brought into contact with the object to be measured, the load becomes a negative value due to the wettability and adsorption properties of the layer in contact with the indenter. Next, a load is applied by the indenter. In this specification, the intermediate layer is loaded until the indentation depth reaches 3000 nm, and the adhesive layer is loaded until the indentation depth reaches 2000 nm. A load curve is created from the displacement from the start of loading to the maximum load. The nanoindentation hardness can be calculated from the maximum load up to the above indentation depth and the contact projected area. Next, the indenter is withdrawn until the load becomes 0. An unloading curve is created from the displacement until the load becomes zero. The adhesive layer and intermediate layer have adsorption and cohesive properties, and when the indenter is withdrawn, components of the adhesive layer and intermediate layer may adhere to the indenter and string together. Therefore, the displacement in the unloading curve may be a negative value. In this specification, the distance (displacement) at which the displacement in the unloading curve becomes negative is called the unloading curve displacement. In this specification, the nanoindentation hardness and unloading curve displacement of the adhesive layer and intermediate layer are both measured in the state when they are laminated as backgrind tape.

[0011] The nanoindentation hardness (25°C) of the intermediate layer is 0.001 MPa to 0.200 MPa, preferably 0.005 MPa to 0.185 MPa, more preferably 0.010 MPa to 0.150 MPa, and even more preferably 0.015 MPa to 0.100 MPa. Figure 2 is a schematic cross-sectional view of the backgrind tape and indenter when performing nanoindenter measurement of the intermediate layer. When performing nanoindenter measurement of the intermediate layer, the substrate 10 side of the backgrind tape 100 is fixed to the support 300 via the adhesive layer 400 of the double-sided tape so that the side of the backgrind tape 100 and the indenter face each other, and the indenter 200 of the nanoindenter is brought into contact with the approximate center of the intermediate layer 20 from the side of the backgrind tape 100 to perform the measurement. In this specification, the nanoindentation hardness of the intermediate layer is measured in the state of the backgrind tape. If the nanoindentation hardness of the intermediate layer measured in the back-grind tape state falls within the above range, a back-grind tape capable of both excellent surface-filling and cutability can be provided. Specifically, the nanoindentation hardness of the intermediate layer is defined as the nanoindentation hardness measured by the following method under room temperature conditions of 25°C. <Nanoindentation hardness> A sample for measurement is prepared by cutting a backgrind tape and using an ultramicrotome under freezing conditions. The indenter is pressed in and withdrawn at a speed of 500 nm / second. The indenter is pressed into the intermediate layer to a depth of 3000 nm over 6 seconds. The holding time after pressing is set to 0 seconds. The indenter is withdrawn from the intermediate layer at the same speed as pressing, and the time until the indenter is withdrawn from the intermediate layer is measured. Note that the time until withdrawal may vary depending on the sample due to the influence of physical properties such as stringiness. The maximum load Pmax (μN) and the contact projected area A (μm) at the maximum depth (3000 nm) in this measurement are recorded. 2The hardness (nanomindentation hardness) (MPa) is calculated from the value of Pmax / A. In nanoindenter measurement, if the thickness of the layer to be measured is 10 times or more the indentation depth, it is considered that the layer laminated on the opposite side from the side into which the indenter is pressed will not be affected. Therefore, if the thickness of the intermediate layer is less than 20 μm, an evaluation adhesive tape with an intermediate layer thickness of 20 μm is prepared and evaluated using the method described above.

[0012] The nanoindentation hardness (25°C) of the adhesive layer is 0.001 MPa to 0.080 MPa, preferably 0.001 MPa to 0.060 MPa, more preferably 0.002 MPa to 0.055 MPa, and even more preferably 0.003 MPa to 0.050 MPa. In this specification, the nanoindentation hardness of the adhesive layer is measured in the state of the backgrind tape. If the nanoindentation hardness of the adhesive layer measured in the state of the backgrind tape is within the above range, a backgrind tape that can achieve both excellent unevenness embedding and cutability can be provided. Specifically, in this specification, the nanoindentation hardness of the adhesive layer measured at room temperature of 25°C by the following method is referred to as the nanoindentation hardness of the adhesive layer. <Nanoindentation hardness> Cut a backgrind tape into pieces approximately 1 cm long and 1 cm wide to prepare a sample for measurement. The indenter should be pressed in and withdrawn at a speed of 500 nm / second. The indenter should be pressed into the adhesive layer to a depth of 2000 nm over 4 seconds. The holding time after pressing should be 0 seconds. The indenter should be withdrawn from the adhesive layer at the same speed as the pressing, and the time until the indenter is withdrawn from the adhesive layer should be measured. Note that the time until withdrawal may vary depending on the sample due to the influence of physical properties such as stringiness. The maximum load Pmax (μN) and the contact projected area A (μm) at the maximum depth (2000 nm) in this measurement should be recorded. 2 From the value of ), the hardness (nanomindentation hardness) (MPa) is calculated using Pmax / A. For the adhesive layer, if the thickness of the adhesive layer is less than 20 μm, an evaluation adhesive tape with an adhesive layer thickness of 20 μm is prepared and evaluated using the method described above.

[0013] As described above, at least one of the pressure-sensitive adhesive layer and the intermediate layer has a thickness of 50 µm or more. When at least one of the layers has a thickness of 50 µm or more, the uneven embedding property can be improved. The layer having a thickness of 50 µm or more has an unloading curve displacement of 8000 µm or less, preferably 7500 µm or less, more preferably 7000 µm or less, still more preferably 6500 µm or less, particularly preferably 5000 µm or less. The unloading curve displacement is preferably as small as possible, and is, for example, 500 µm or more. As described above, the unloading curve displacement is measured in the state of a backgrinding tape. When the unloading curve displacement measured in the state of a backgrinding tape falls within the above range, a semiconductor wafer that achieves both excellent uneven embedding property and cutting property can be provided. In the present specification, the unloading curve displacement refers to the distance at which the displacement becomes negative (that is, the displacement amount from the point when the displacement becomes 0 nm to the point when the load becomes 0 in the unloading curve) obtained by creating a load-displacement curve from the load and the indentation depth when measuring the nanoindentation hardness, and extracting the value from the unloading curve of the load-displacement curve.

[0014] The backgrinding tape may further include any appropriate layer other than a base material, an intermediate layer, and a pressure-sensitive adhesive layer. For example, it may further include an antistatic layer. When the antistatic layer is provided, electrostatic breakdown of a semiconductor element caused by static electricity during peeling of the backgrinding tape can be prevented.

[0015] The thickness of the backgrinding tape can be set to any appropriate range. It is preferably 10 µm to 1000 µm, more preferably 50 µm to 300 µm, still more preferably 100 µm to 300 µm.

[0016] 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. Using these resins can further prevent warping.

[0017] 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, heat stabilizers, and the like. The type and amount of other components used can be any appropriate amount depending on the purpose.

[0018] In one embodiment, the substrate has an antistatic function. If the substrate has an antistatic function, 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. When the substrate has an antistatic function, the surface resistance of the substrate is, for example, 1.0 × 10⁻⁶. 2 Ω / □~1.0×10 13 It is Ω / □.

[0019] The thickness of the substrate can be set to any appropriate value. The thickness of the substrate is preferably 10 μm to 200 μm, and more preferably 20 μm to 150 μm.

[0020] The modulus of elasticity of the substrate can be set to any appropriate value. Preferably, the modulus of elasticity of the substrate is 50 MPa to 6000 MPa, and more preferably 70 MPa to 5000 MPa. If the modulus of elasticity is within the above range, a backgrind tape that can adequately conform to the irregularities of the adherend surface can be obtained.

[0021] C. middle class 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. If the thickness of the intermediate layer is within the above range, a backgrind tape that can effectively fill uneven surfaces can be obtained. As described above, when the thickness of the intermediate layer is 50 μm or more, the unloading curve displacement is 8000 μm or less.

[0022] The product of the nanoindentation hardness (MPa) and thickness (μm) of the intermediate layer is preferably 0.050 to 15.000, more preferably 0.400 to 10.000, and even more preferably 1.000 to 8.000. If the product of nanoindentation hardness and thickness is within the above range, a backgrind tape that can achieve both better embedding properties for uneven surfaces and better cutability can be obtained.

[0023] The intermediate layer can be formed from any suitable material. The intermediate layer can be formed from any suitable resin, such as acrylic resins, polyethylene resins, ethylene-vinyl alcohol copolymers, ethylene vinyl acetate resins, and ethylene methyl methacrylate resins, or from an adhesive.

[0024] In one embodiment, the intermediate layer is preferably formed from an intermediate layer-forming composition comprising a (meth)acrylic polymer. The (meth)acrylic polymer preferably 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)acrylic acid 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. Note that "(meth)acrylic" refers to acrylic and / or methacrylic.

[0025] The intermediate layer preferably contains a (meth)acrylic polymer obtained by polymerizing a monomer composition containing a monomer having a glass transition temperature of 80°C or higher (hereinafter also referred to as a high-Tg monomer). If a monomer with a glass transition temperature of 80°C or higher is included, a backgrind tape with better cutting performance can be obtained. The glass transition temperature of the high-Tg monomer is more preferably 90°C or higher, and even more preferably 100°C or higher. The glass transition temperature of the high-Tg monomer is, for example, 180°C or lower. In this specification, the glass transition temperature of a monomer refers to the glass transition temperature of the homopolymer of the monomer. Examples of high-Tg monomers include cyclohexyl methacrylate (Tg: 83°C), dicyclopentanyl acrylate (Tg: 120°C), dicyclopentanyl methacrylate (Tg: 175°C), isobornyl acrylate (Tg: 94°C), isobornyl methacrylate (Tg: 150°C), t-butyl methacrylate (Tg: 118°C), methyl methacrylate (Tg: 105°C), trimethylolpropane triacrylate (Tg: >250°C), styrene (Tg: 80°C), acrylonitrile (Tg: 97°C), and N-acryloylmorpholine (Tg: 145°C). Methyl methacrylate is preferably used as the high-Tg monomer. The Tg of homopolymers other than those listed above can be determined, for example, from "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999). If multiple Tg values ​​are listed in this document, the "conventional" value should be used.

[0026] High-Tg monomers can be used in any appropriate proportion. The proportion of high-Tg monomers is preferably 5% to 50% by weight, more preferably 10% to 40% by weight, and even more preferably 15% to 35% by weight in the monomer composition.

[0027] 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 (meth)acrylic polymer.

[0028] The weight-average molecular weight of the above (meth)acrylic polymer is preferably 100,000 to 1,000,000, and more preferably 300,000 to 800,000. The weight-average molecular weight can be measured by GPC (solvent: THF).

[0029] 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, if the intermediate layer contains a photopolymerization initiator, the photopolymerization initiator contained in the adhesive layer migrates to the intermediate layer, which can suppress the decrease in the photopolymerization initiator content in the adhesive layer over time. Therefore, the backgrind tape can exhibit excellent easy peelability after UV irradiation. In this specification, an UV-curable component refers to a component that can crosslink and harden upon UV irradiation. Specifically, this includes polymers having polymerizable carbon-carbon double bonds in their side chains or terminals.

[0030] 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. If 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 can be used. Only one type of photopolymerization initiator may be used, or two or more types may be used in combination.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] D.Adhesive layer The adhesive layer can be formed using any suitable adhesive. Typically, the adhesive contains a base polymer. Preferably, the adhesive layer is formed with an ultraviolet-curable adhesive. If formed with an ultraviolet-curable adhesive, a backgrind tape with excellent peelability can be obtained.

[0036] D-1. Base Polymer Any suitable adhesive can be used as the UV-curable adhesive. For example, it may be an adhesive to which UV-curable monomers and / or oligomers have been added to any suitable adhesive such as an acrylic adhesive, rubber adhesive, silicone adhesive, or polyvinyl ether adhesive, or it may be an adhesive using a polymer in which polymerizable carbon-carbon double bonds have been introduced into the side chains and / or terminals as the base polymer. Preferably, an adhesive using a polymer in which polymerizable carbon-carbon double bonds have been introduced into the side chains and / or terminals as the base polymer is used.

[0037] When using an adhesive that utilizes a polymer in which polymerizable carbon-carbon double bonds are introduced into the side chains and / or terminals, the base polymer used is a polymer in which polymerizable carbon-carbon double bonds are introduced into the side chains and / or terminals and which is also adhesive. Examples of such polymers include polymers in which polymerizable carbon-carbon double bonds are introduced into resins such as acrylic resins, vinyl alkyl ether resins, silicone resins, polyester resins, polyamide resins, urethane resins, and styrene-diene block copolymers. Preferably, an acrylic resin in which polymerizable carbon-carbon double bonds are introduced into an acrylic resin is used. Using an acrylic resin makes it easy to adjust the storage modulus and tensile modulus of the adhesive layer, and allows for the creation of an adhesive sheet with an excellent balance between adhesive strength and release properties. Furthermore, contamination of semiconductor wafers by components derived from the adhesive can be reduced.

[0038] Any suitable acrylic resin can be used as the acrylic resin. Examples of acrylic resins include polymers obtained by polymerizing a monomer composition containing one or more esters of acrylic acid or methacrylic acid having linear or branched alkyl groups.

[0039] 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.

[0040] The monomer composition may contain any other suitable monomers. Other monomers include, for example, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; (meth)acrylate 2-hydroxyethyl, (meth)acrylate 2-hydroxypropyl, (meth)acrylate 4-hydroxybutyl, (meth)acrylate 6-hydroxyhexyl, (meth)acrylate 8-hydroxyoctyl, (meth)acrylate 10-hydroxydecyl, (meth)acrylate 12-hydroxylauryl, (4-hydroxy Examples of functional group-containing monomers include hydroxyl group-containing monomers such as hydroxymethylcyclohexyl)-methyl acrylate, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate. If functional group-containing monomers are included, an acrylic resin that readily incorporates polymerizable carbon-carbon double bonds can be obtained. The content ratio of the functional group-containing monomer is preferably 4 to 30 parts by weight, and more preferably 6 to 20 parts by weight, per 100 parts by weight of the total monomer components of the monomer composition.

[0041] The weight-average molecular weight of the acrylic resin is preferably 100,000 or more, more preferably 300,000 or more, even more preferably 500,000 or more, and particularly preferably 800,000 to 3,000,000. 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 molecular weight distribution (weight-average molecular weight / number-average molecular weight) of the (meth)acrylic resin is preferably 1 to 20, more preferably 3 to 10. By using a (meth)acrylic resin with a narrow molecular weight distribution, bleeding of low molecular weight components can be prevented, and a low-contamination adhesive sheet can be obtained. The weight-average molecular weight and number-average molecular weight can be determined by gel permeation chromatography (solvent: tetrahydrofuran, polystyrene equivalent).

[0042] Polymers in which polymerizable carbon-carbon double bonds are introduced in the side chains and / or terminals can be obtained by any suitable method. For example, they can be obtained by reacting (e.g., condensation reaction, addition reaction) a resin obtained by any suitable polymerization method with a compound having polymerizable carbon-carbon double bonds. Specifically, when using an acrylic resin, an acrylic resin (polymer) having constituent units derived from monomers having any suitable functional groups can be polymerized in any suitable solvent, and then the functional groups of the acrylic resin can be reacted with a compound having polymerizable carbon-carbon double bonds that can react with the functional groups to obtain an acrylic resin into which polymerizable carbon-carbon double bonds have been introduced. The amount of the compound having polymerizable carbon-carbon double bonds 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 resin. Any suitable solvent can be used as the solvent, for example, various organic solvents such as ethyl acetate, methyl tyl ketone, and toluene.

[0043] When a resin and a compound having a polymerizable carbon-carbon double bond are reacted as described above, it is preferable that both the resin and the compound having a polymerizable carbon-carbon double bond have functional groups that can react with each other. Examples of functional group combinations include carboxyl group / epoxy group, carboxyl group / aziridine group, and hydroxyl group / isocyanate group. Among these functional group combinations, the combination of a hydroxyl group and an isocyanate group is preferred due to the ease of reaction tracking.

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

[0045] D-2. Photopolymerization Initiator Any suitable initiator can be used as the 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-hydroxycyclohexylphenylketone; and 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 benzyldimethyl 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 Examples include 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 and 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.

[0046] Commercially available photopolymerization initiators may be used. Examples include Omnirad 127 and Omnirad 651 from IGM Resins.

[0047] The photopolymerization initiator is 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, it may not cure sufficiently when irradiated with ultraviolet light. If the content of the photopolymerization initiator exceeds 10 parts by weight, the storage stability of the adhesive may decrease.

[0048] The adhesive preferably further comprises a polyfunctional acrylate. Further inclusion of a polyfunctional acrylate reduces the elasticity of the adhesive layer, potentially yielding a backgrind tape with superior filling properties for uneven surfaces. Furthermore, UV irradiation reduces the adhesive strength, potentially yielding a backgrind tape with superior ease of peeling. Examples of polyfunctional acrylates include (meth)acrylate oligomers and monomers. Specifically, examples include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy(meth)acrylate, polyester(meth)acrylate, urethane(meth)acrylate, etc., as well as various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers. The molecular weight of these oligomer components should be in the range of approximately 100 to 30,000. They can be used individually or in combination of two or more.

[0049] The polyfunctional acrylate is used in any appropriate amount. For example, it is 1 to 80 parts by weight, preferably 10 to 50 parts by weight, and more preferably 25 to 45 parts by weight, per 100 parts by weight of the base polymer. If the polyfunctional acrylate content is within the above range, the elasticity of the adhesive layer decreases, and a backgrind tape with better filling properties for uneven surfaces can be obtained. In addition, the adhesive strength decreases with UV irradiation, and a backgrind tape with better peelability can be obtained.

[0050] D-3. Additives The adhesive may contain any suitable additives as needed. 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.

[0051] In one embodiment, the adhesive further comprises 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 ratio 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, per 100 parts by weight of the base polymer contained in the adhesive. The flexibility of the adhesive layer can be controlled by the content ratio of the crosslinking agent. If the crosslinking agent content is less than 0.01 parts by weight, the adhesive may become sol-like and may not be able to form an adhesive layer. If the crosslinking agent content exceeds 10 parts by weight, the adhesion to the semiconductor wafer may decrease and the semiconductor wafer may not be adequately protected.

[0052] 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. If an isocyanate-based crosslinking agent is used as the crosslinking agent, and the content of the crosslinking agent is within the above range, an adhesive layer can be formed that exhibits excellent peelability and significantly reduces adhesive residue even after heating.

[0053] The thickness of the adhesive layer can be set to any appropriate value. Preferably, the thickness of the adhesive layer is 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 30 μm. If the thickness of the adhesive layer is within the above range, it can exhibit sufficient adhesion to the semiconductor wafer. As described above, when the thickness of the adhesive layer is 50 μm or more, the unloading curve displacement is 8000 μm or less.

[0054] The product of the nanoindentation hardness (MPa) and thickness (μm) of the adhesive layer is preferably 0.001 to 1.000, more preferably 0.050 to 1.000, even more preferably 0.075 to 0.800, and particularly preferably 0.100 to 0.600. If the product of nanoindentation hardness and thickness is within the above range, a backgrind tape that can achieve both better embedding properties for uneven surfaces and better cutability can be obtained.

[0055] The adhesive layer may be one layer or two or more layers. If there are two or more adhesive layers, at least one adhesive layer formed using an adhesive containing the above-mentioned photopolymerization initiator is sufficient. When there are two or more adhesive layers, preferably an adhesive layer formed using an adhesive containing the photopolymerization initiator is formed on the surface of the adhesive sheet that contacts the semiconductor wafer. The adhesive layer not formed by the UV-curable adhesive can be formed with any suitable adhesive composition. This adhesive composition may be a UV-curable adhesive or a pressure-sensitive adhesive.

[0056] The adhesive layer may have any appropriate adhesive strength. The adhesive strength of the adhesive layer to the silicon wafer before UV irradiation is preferably 0.50 N / 20 mm to 30 N / 20 mm, more preferably 1.00 N / 20 mm to 25 N / 20 mm, and even more preferably 1.50 N / 20 mm to 20 N / 20 mm. In this specification, the adhesive strength of the adhesive layer is measured by cutting the backgrind tape to a width of 20 mm and a length of 80 mm, pressing the adhesive layer of the backgrind tape onto the mirror surface of a silicon mirror wafer with a 2 kg roller in a 23°C atmosphere by one back-and-forth motion, leaving it at 23°C for 30 minutes, and then performing a 180° peel test at a tensile speed of 300 mm / min in a 23°C, 50% RH atmosphere.

[0057] The adhesive strength of the adhesive layer to the silicon wafer after UV 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 0.005 N / 20 mm to 0.800 N / 20 mm. The adhesive strength after UV irradiation is measured by cutting the backgrind tape 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 with a 2 kg roller in a 23°C atmosphere with one back-and-forth motion, leaving it at 23°C for 30 minutes, and then irradiating it with ultraviolet (UV) light at an integrated intensity of 1000 mJ / cm². 2 This refers to the value measured by irradiating the backgrind tape from the substrate side to achieve a (365nm equivalent) value, followed by a 180° peel test performed under conditions of 23°C, 50%RH atmosphere, and a tensile speed of 300 mm / min.

[0058] E. Method for manufacturing backgrind tape Backgrind tape can be manufactured by any suitable method. In one embodiment, backgrind tape 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 a composition for forming the adhesive layer and a 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 employed, 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 employed in which the adhesive layer or intermediate layer is formed on a release liner and then bonded to the substrate.

[0059] 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 can achieve both excellent unevenness filling properties and cutability. Therefore, the backgrind tape according to the embodiment of the present invention can be suitably used in the processing of semiconductor devices.

[0060] In one embodiment, it is preferable that the bump height (μm) and the sum of the adhesive layer thickness (μm) and the intermediate layer thickness (μm) satisfy the relationship bump height (μm) < adhesive layer thickness (μm) + intermediate layer thickness (μm). Also, the bump height (μm) and the intermediate layer thickness (μm) satisfy the relationship bump height (μm) < intermediate layer thickness (μm). If these relationships are satisfied, a backgrind tape with better embedding properties for uneven surfaces can be obtained. [Examples]

[0061] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "parts" and "%" are based on weight.

[0062] [Example 1] 1. Preparation of the intermediate layer forming composition As monomer components, 73.7% by weight of butyl acrylate (BA), 19.2% by weight of methyl methacrylate (MMA), and 7.1% by weight of 2-hydroxyethyl acrylate (HEA) (manufactured by Toagosei Co., Ltd., trade name: Acrylics® HEA) were used. A monomer composition (solid content concentration: 40%) was prepared by mixing 0.3% by weight of polymerization initiator (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: 2,2'-azobis(isobutyronitrile) (AIBN)) with a solvent (ethyl acetate) relative to the total weight of the monomer components. The obtained 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 purged at room temperature for 2 hours while stirring. Subsequently, solution polymerization was carried out by injecting nitrogen and stirring while maintaining the temperature at 65°C for 6 hours to obtain a resin solution (solid content 40% by weight). To 100 parts by weight of the solid content of the obtained resin solution, 0.1 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L") and 1 part by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name: Omnirad 127D) were mixed to prepare an intermediate layer forming composition containing ethyl acetate (solid content 23%).

[0063] 2. Preparation of the adhesive composition The monomer components used were 76.8% by weight of butyl acrylate (BA), 7.5% by weight of methyl methacrylate (MMA), and 8.7% by weight of 2-hydroxyethyl acrylate (HEA, manufactured by Toagosei Co., Ltd., trade name: Acrylics®). A polymerization initiator (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: 2,2'-azobis(isobutyronitrile) (AIBN)) and a solvent (ethyl acetate) were mixed at 0.3% by weight relative to the total weight of the monomer components to obtain the monomer composition. A material (solid content: 37.5%) was prepared. The obtained 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. Nitrogen was purged at room temperature for 2 hours while stirring. Then, solution polymerization was carried out at 65°C for 6 hours while stirring under nitrogen inflow to obtain a resin solution. After that, it was aged at 78°C for 2 hours. The resulting resin solution was stirred to allow sufficient air to enter, and 7.0% by weight of a radiation-polymerizable carbon-carbon double bond compound (Showa Denko Corporation, trade name "Kalenz MOI") was added. Furthermore, 0.05% by weight of dibutyltin IV dilaurate (Wako Pure Chemical Industries, Ltd.) was added relative to the weight of the radiation-polymerizable carbon-carbon double bond compound, and solvent (ethyl acetate) was added as needed to adjust the solid content to 25%, and the mixture was stirred. After that, it was stored at 50°C for 24 hours to obtain a polymer solution (solid content: 25%). To 100 parts by weight of the solids content of the obtained polymer solution, 0.75 parts by weight of a polyisocyanate compound (manufactured by Tosoh Corporation, trade name "Coronate L"), 1 part by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad 127D"), and 40 parts by weight of a polyfunctional acrylate (manufactured by Toagosei Co., Ltd., trade name "Aronics® M-321") were mixed to prepare an adhesive composition containing ethyl acetate (solids content 15%).

[0064] 3. Making the tape The intermediate layer-forming composition obtained in step 1 was applied to the silicone-treated surface of a 38 μm thick polyester-based release liner (manufactured by Mitsubishi Chemical Corporation, trade name "Diafoil®"), and the solvent was removed by heating at 120°C for 120 seconds to form a 100 μm thick intermediate layer. Next, a 50 μm thick PET film (manufactured by Toray Industries, Ltd., trade name "Lumirror®") was laminated to the surface of the intermediate layer as a substrate. Separately, the adhesive composition obtained in step 2 was applied to the silicone-treated surface of a 75 μm thick polyester-based release liner, and the solvent was removed by heating at 120°C for 120 seconds to form an adhesive layer with a thickness of 20 μm. Next, the release liner was peeled off the intermediate layer, and the adhesive layer was attached to the surface of the intermediate layer from which the release liner had been peeled off and transferred. The tape was then stored at 50°C for 72 hours to obtain an adhesive tape (backgrind tape) having the base material / intermediate layer / adhesive layer in this order.

[0065] [Examples 2-4] An adhesive tape (backgrind tape) was obtained in the same manner as in Example 1, except that the monomer compositions, the composition of the intermediate layer forming composition, and the composition of the adhesive layer forming composition were changed as shown in Table 1.

[0066] [Example 5] As monomer components, 64% by weight of butyl acrylate (BA), 33% by weight of methyl methacrylate (MMA), and 3% by weight of 2-hydroxyethyl acrylate (HEA) (manufactured by Toagosei Co., Ltd., trade name: Acrylics® HEA) were used, respectively. A 10% by weight aqueous solution of the monomer components and emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Aqualon KH-1025") and water were placed in a glass bottle, and nitrogen bubbling was performed for 5 minutes. Next, the mixture was stirred at 6000 rpm for 5 minutes using a homodisperser to obtain emulsified monomers. A 10% by weight aqueous solution of emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Aqualon KH-1025") was placed in a separable flask equipped with a condenser, and nitrogen purging was performed for 1 hour while stirring. After that, it was held at 70°C for 20 minutes. Next, 0.02 parts by weight of a 5% aqueous solution of azo polymerization initiator (Fujifilm, product name "VA-057") was added, and the emulsion monomer was immediately added dropwise over 3 hours. After the addition was complete, the mixture was aged at 70°C for 3 hours. Then, salting out was performed, the solution after salting out was filtered, and the filtrate was dried to obtain the polymer. This polymer was dissolved in ethyl acetate to obtain a polymer solution with a solid content of 35% by weight. To 100 parts by weight of the solid content of the obtained polymer solution, 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 to prepare an intermediate layer forming composition containing ethyl acetate. An adhesive tape (backgrind tape) was obtained in the same manner as in Example 1, except that the intermediate layer forming composition obtained above was used, and the monomer composition of the base polymer of the adhesive composition, the composition of the intermediate layer forming composition, and the composition of the adhesive layer forming composition were changed as shown in Table 1.

[0067] [Examples 6-8] An adhesive tape (backgrind tape) was obtained in the same manner as in Example 1, except that the monomer compositions, the composition of the intermediate layer forming composition, and the composition of the adhesive layer forming composition were changed as shown in Table 1.

[0068] (Comparative Examples 1-4) An adhesive tape (backgrind tape) was obtained in the same manner as in Example 1, except that the monomer compositions, the composition of the intermediate layer forming composition, and the composition of the adhesive layer forming composition were changed as shown in Table 1.

[0069] [Table 1]

[0070] <Rating> The following evaluations were performed using the adhesive tapes obtained in the examples and comparative examples. The results are shown in Table 2. 1. Nanoindenter measurement of the intermediate layer Samples for measurement were prepared using an ultramicrotome under freezing conditions after cutting out the adhesive tapes obtained in the examples and comparative examples. Specifically, the adhesive tape was rapidly frozen in a liquid nitrogen atmosphere, and a cross-section was prepared by cutting in the thickness direction under a freezing atmosphere of -30°C using an ultramicrotome (freezing microtome manufactured by Daiwa Koki Kogyo Co., Ltd.). After preparing the cross-section, the sample was left at room temperature for more than 2 hours, and nanoindenter measurement was performed. A nanoindenter manufactured by Hysitron Inc. (product name: Triboindenter) was used for the measurement. A Berkovich indenter (triangular pyramid, indenter interior angle: 142.35°, angle between the center line and the face: 65.35°, indenter aspect ratio: 1:8) was used as the indenter. The measurement was performed at 25°C using a single indentation measurement. The backgrind tape was fixed with a support as shown in Figure 2. Specifically, the substrate side of the backgrind tape and the support (brass base) were bonded together using double-sided tape (Nitto Corporation, product name "No. 5605", adhesive layer thickness: 0.05 mm). During bonding, one end of the brass base and one end of the backgrind tape were bonded flush. As shown in the illustrated example, the indenter was placed so that the flush side corresponded to the indenter, and the Berkovich indenter was brought into contact with the approximate center of the intermediate layer on the side of the backglide tape (the side of the cross-section prepared above), and measurements were taken. The indenter was pushed in and pulled out at a speed of 500 nm / second. The indenter was pushed into the intermediate layer to a depth of 3000 nm over 6 seconds, with a holding time of 0 seconds. Next, the indenter was pulled out of the intermediate layer at the same speed as when it was pushed in, and the time until the indenter was pulled out of the intermediate layer was measured. The maximum load Pmax (μN) and the contact projected area A (μm) at the maximum depth were measured. 2 From the values ​​of ), the hardness (nanomindentation hardness) (MPa) was calculated using Pmax / A. Furthermore, a load-displacement curve was created from the load and indentation depth during the above measurements. From the unloading curve of the load-displacement curve, the distance at which the displacement became negative (i.e., the amount of displacement from the point where the displacement became 0 nm to the point where the load became 0 on the unloading curve) was measured and defined as the unloading curve displacement (μm). If the unloading curve displacement is 8000 μm or less, the cutting performance may be good. Measurements were performed using three samples, and the average values ​​were used as the nanoindentation hardness and the unloading curve displacement.

[0071] 2. Nanoindenter measurement of the adhesive layer The adhesive tapes obtained in the examples and comparative examples were cut into pieces approximately 1 cm long and 1 cm wide to be used as measurement samples. The release liner was peeled off, and the hardness of the adhesive layer and the displacement of the unloading curve were measured. A nanoindenter (product name: Triboindenter) manufactured by Hysitron Inc. was used for the measurements. The Berkovich indenter (triangular pyramid, interior angle of the indenter: 142.35°, angle between the center line and the face: 65.35°, aspect ratio of the indenter: 1:8) was measured at 25°C using a single indentation measurement. As shown in Figure 3, the indenter was brought into contact with the approximate center of the adhesive layer of the measurement sample for the measurement. The indenter was pressed in and withdrawn at a speed of 500 nm / second. The indenter was pressed into the adhesive layer to a depth of 2000 nm over 4 seconds, with a holding time of 0 seconds. Next, the indenter was withdrawn from the adhesive layer at the same speed as the indentation, and the time taken until the indenter was withdrawn from the adhesive layer was measured. The maximum load Pmax (μN) and the contact projected area A (μm) at the maximum depth were measured. 2 The hardness (nanomindentation hardness) (MPa) was calculated from the value of Pmax / A. For adhesive tapes with an adhesive layer thickness of less than 20 μm, an evaluation adhesive tape with an adhesive layer thickness of 20 μm was prepared and evaluated using the method described above. Furthermore, a load-displacement curve was created from the load and indentation depth during the above measurements. From the unloading curve of the load-displacement curve, the distance at which the displacement became negative (i.e., the amount of displacement from the point where the displacement became 0 nm to the point where the load became 0 on the unloading curve) was measured and defined as the unloading curve displacement (μm). If the unloading curve displacement is 8000 μm or less, the cutting performance may be good. Measurements were performed using three samples, and the average values ​​were used as the nanoindentation hardness and the unloading curve displacement.

[0072] 3. Implantability The adhesive tapes obtained in the examples and comparative examples were cut to 230 cm x 400 cm. The cut adhesive tapes were attached to wafers (8 inches, 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. Roller pressure: 0.40 MPa Roller speed: 5 mm / second Table temperature: 80℃ After application, the adhesion state of the adhesive sheet and wafer was observed using a laser microscope (magnification: 100x). Furthermore, images were taken of the adhesive tape and wafer with the adhesive tape facing upwards, and the images were binarized (8-bit grayscale, brightness: 0-255, threshold: 114) using image analysis software (Image J (free software)). Then, five bumps were arbitrarily selected from the wafer, and the number of dots used to display each bump was measured. The image of only the bumps without tape attached had 220 dots, and the closer the number of dots measured with the adhesive tape attached was to 220, the better the embedding performance. When adhesive tape is attached to a semiconductor wafer with bumps, the number of dots is usually around 820. Bumps with an average number of dots of 830 or less were evaluated as ○ (good), and those with an average number of dots exceeding 830 were evaluated as × (poor).

[0073] 4. Thread pulling The adhesive tapes obtained in the examples and comparative examples were cut to 230 cm x 400 cm. The cut adhesive tapes were attached to an 8-inch silicon mirror wafer using a tape application device (manufactured by Nitto Seiki Co., Ltd., product name: DR-3000III), and then the adhesive tapes attached to the wafer were cut to match the shape of the wafer. For cutting, a cutter blade specifically for the DR-3000III tape application device was used, and a new cutter blade was used for each measurement. The application was carried out under the following conditions. Roller pressure: 0.27 MPa Roller speed: 20 mm / second Table temperature: 23℃ Cutter speed: 200 mm / second Cutter temperature: 180℃ The laminate of the cut adhesive tape and wafer was observed from the side of the wafer using a digital microscope, and samples with and without stringing in the intermediate layer were evaluated as "none" and "present." The absence of stringing in the intermediate layer is preferable.

[0074] [Table 2]

[0075] The adhesive tape of the embodiment of the present invention exhibited excellent surface embedding properties on semiconductor wafers having uneven surfaces. Furthermore, stringing was suppressed, which helped to prevent wafer damage during peeling. [Industrial applicability]

[0076] The backgrind tape according to the embodiment of the present invention can be suitably used as a backgrind tape for semiconductor wafer processing. [Explanation of symbols]

[0077] 10 Base material 20 Middle Class 30 Adhesive layer 100 Backgrind Tapes 200 indenter 300 Support

Claims

1. It comprises a base material, an intermediate layer, and an adhesive layer. The nanoindentation hardness (at 25°C) of the intermediate layer is 0.001 MPa to 0.200 MPa. The nanoindentation hardness (at 25°C) of the adhesive layer is 0.001 MPa to 0.080 MPa. The thickness of at least one of the intermediate layer and the adhesive layer is 50 μm or more. A backgrind tape in which the unloading curve displacement of a layer with a thickness of 50 μm or more is 8000 μm or less.

2. The backgrind tape according to claim 1, wherein the product of the nanoindentation hardness (MPa) and thickness (μm) of the intermediate layer is 0.050 to 15.

000.

3. The backgrind tape according to claim 1, wherein the product of the nanoindentation hardness (MPa) and thickness (μm) of the adhesive layer is 0.001 to 1.

000.

4. The backgrind tape according to claim 1, wherein the thickness of the adhesive layer is 1 μm to 50 μm.

5. The backgrind tape according to claim 1, wherein the intermediate layer comprises a (meth)acrylic polymer obtained by polymerizing a monomer composition containing a monomer having a glass transition temperature of 80°C or higher.

6. The backgrind tape according to claim 5, wherein the intermediate layer comprises a (meth)acrylic polymer obtained by polymerizing a monomer composition containing 5% to 50% by weight of a monomer having a glass transition temperature of 80°C or higher.

7. The backgrind tape according to claim 1, wherein the adhesive layer is formed of an ultraviolet-curing adhesive.

8. The backgrind tape according to claim 1, wherein the adhesive layer is formed of an adhesive containing a polyfunctional acrylate.

9. The semiconductor wafer on which the bumps are formed is bonded to it. The backgrind tape according to claim 1, wherein the height of the bump (μm) and the sum of the thickness of the adhesive layer (μm) and the thickness of the intermediate layer (μm) satisfy the relationship: height of bump (μm) < thickness of adhesive layer (μm) + thickness of intermediate layer (μm).

10. The semiconductor wafer on which the bumps are formed is bonded to it. The backgrind tape according to claim 1, wherein the height of the bump (μm) and the thickness of the intermediate layer (μm) satisfy the relationship: height of bump (μm) < thickness of intermediate layer (μm).

Images