Adhesive tape

Abstract

To provide an adhesive tape that can be easily peeled off the surface of the adherend after processing, and which further suppresses the residue of fine particles on the adherend surface. [Solution] The adhesive tape of the embodiment of the present invention comprises a base material and an adhesive layer made of an active energy ray curable adhesive, wherein the sol component of the adhesive layer after irradiation with active energy rays contains 20% or less of a component with a weight-average molecular weight of 1000 or less, and the adhesive strength of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less.

Description

[Technical Field]

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

[0002] Adhesive tapes are widely used for surface protection and fixation of adherends. For example, in the semiconductor wafer processing process, they are used to properly hold the semiconductor wafer, which is the adherend, during the backgrinding and dicing processes. In recent years, with the miniaturization and thinning of chips, adhesive tapes are required to have sufficient adhesive strength to properly hold the semiconductor wafer even when it is thinly ground during processing. Processed semiconductor wafers tend to be thin and easily damaged, and there is a risk of damage to the semiconductor wafer when the adhesive tape is removed. Therefore, there is a need for adhesive tapes that can be easily removed from the adherend after processing. As such adhesive tapes, adhesive tapes using ultraviolet-curing adhesives have been proposed (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-31620 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, even when using such adhesive tapes, fine foreign matter may remain on the wafer surface after the adhesive tape is removed. This fine foreign matter on the surface can adversely affect the functionality of the manufactured semiconductor wafer. In recent years, semiconductor performance has been increasing, and the retention of such fine foreign matter can be a particular problem in the manufacturing of high-performance semiconductors. Therefore, there is a need for adhesive tapes that can be easily peeled off the adherend surface after processing and that further suppress the retention of fine particles on the adherend surface. [Means for solving the problem]

[0005] 1. The adhesive tape according to an embodiment of the present invention includes a base material and an adhesive layer made of an active energy ray-curable adhesive, wherein the component having a weight average molecular weight of 1000 or less contained in the sol content of the adhesive layer after irradiation with active energy rays is 20% or less, and the adhesive force of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less. 2. In the adhesive tape according to 1 above, the active energy ray-curable adhesive may be a water-dispersed adhesive. 3. In the adhesive tape according to 1 or 2 above, the active energy ray-curable adhesive may contain a water-dispersed acrylic polymer and an active energy ray-curable resin. 4. In the adhesive tape according to 3 above, the active energy ray-curable resin may contain urethane (meth) acrylate. 5. In the adhesive tape according to 3 or 4 above, the HSP value distance between the water-dispersed acrylic polymer and the active energy ray-curable resin may be 8 or less. 6. The adhesive tape according to any one of 1 to 5 above may be used for semiconductor wafer processing.

Advantages of the Invention

[0006] According to an embodiment of the present invention, an adhesive tape that can be easily peeled off from the surface of the adherend after processing and in which the residue of fine particles on the surface of the adherend is further suppressed can be provided.

Brief Description of the Drawings

[0007] [Figure 1] It is a schematic cross-sectional view of an adhesive tape according to one embodiment of the present invention.

Modes for Carrying Out the Invention

[0008] A. Adhesive Tape A-1. Overall Configuration of Adhesive Tape The adhesive tape according to an embodiment of the present invention includes a base material and an adhesive layer made of an active energy ray-curable adhesive. The component having a weight average molecular weight of 1000 or less contained in the sol fraction of the adhesive layer after irradiation with active energy rays (hereinafter also referred to as a low molecular weight component) is 20% or less, and the adhesive force of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less. With such an adhesive tape, it can be easily peeled off from the surface of the adherend after processing, and an adhesive tape with further suppressed residue of fine particles on the surface of the adherend can be provided. It is considered that the component having a weight average molecular weight of 1000 or less contained in the sol fraction of the adhesive layer after irradiation with active energy rays becomes fine particles and remains on the surface of the adherend, which may contribute to fine particle contamination of the adherend bottom surface. If the low molecular weight component contained in the sol fraction is 20% or less, fine particle contamination of the surface of the adherend after peeling of the adhesive tape can be suppressed. Further, the adhesive force of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less. If the adhesive force of the adhesive layer after irradiation with active energy rays is 0.04 N / 200 mm or less, it can be more easily peeled off from the adherend. As a result, it can be suppressed that fine components derived from the adhesive layer remain on the surface of the adherend at the time of peeling.

[0009] FIG. 1 is a schematic cross-sectional view of an adhesive tape according to an embodiment of the present invention. The adhesive tape 100 includes a base material 20 and an adhesive layer 10 in this order. The adhesive tape 100 may further include any appropriate layer. For example, an intermediate layer (not shown) may be formed between the base material 20 and the adhesive layer 10. When the intermediate layer is included, the adhesion to an adherend having irregularities on the surface can be improved. In one embodiment, an antistatic layer may be formed.

[0010] The proportion of components with a weight average molecular weight of 1000 or less in the sol fraction of the adhesive layer after active energy ray irradiation is 20% or less, preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. The smaller the proportion of components with a weight average molecular weight of 1000 or less in the sol fraction, the more preferable, and it may even be 0%. In this specification, the proportion of components with a weight average molecular weight of 1000 or less in the sol fraction of the adhesive layer after active energy ray irradiation refers to the proportion of components with a weight average molecular weight of 1000 or less in the soluble fraction when the soluble fraction of the adhesive tape after active energy ray irradiation is taken as 100. Specifically, it refers to the value obtained by the following method. <Measurement of Low Molecular Weight Components in Sol Fraction> Collect about 0.1 part by weight of a sample (adhesive layer and base material) from the adhesive tape after active energy ray irradiation. When the material used for the base material contains components that can elute in ethyl acetate (for example, additives such as plasticizers and antistatic agents), the base material is peeled off and only 0.1 part by weight of the adhesive layer is used. Wrap the collected sample with a porous polytetrafluoroethylene membrane with an average pore size of 0.2 μm (for example, the product name "Nitoflon (registered trademark) NTF1122" manufactured by Nitto Denko Corporation, and its equivalent products), and tie it with string. Then, immerse it in 50 mL of ethyl acetate at room temperature for 7 days to elute the soluble fraction (sol fraction) outside the membrane. Next, collect the entire amount of the soluble fraction into a screw tube, and leave the soluble fraction solution in the screw tube at room temperature to air-dry. Then, add tetrahydrofuran (THF) to the solid content remaining in the screw tube so that it becomes 3.3 g / L, and let it stand for 1 day to dissolve. After filtering this solution with a syringe filter, measure the molecular weight of the soluble fraction (sol fraction) by the GPC method under the following conditions, and create a molecular weight curve. Calculate the area ratio of the components with a weight average molecular weight (Mw) of 1000 or less to the total area of the molecular weight curve obtained. <GPC Measurement Conditions> Measurement conditions: Sample introduction amount 500 mg, column temperature 40 °C, flow rate 1.0 mL / min Apparatus: Manufactured by Tosoh Corporation, product name "HLC 8320GPC"

[0011] The gel fraction of the adhesive tape after irradiation with active energy rays is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. A higher gel fraction of the adhesive tape after irradiation with active energy rays is preferable. If the gel fraction of the adhesive tape after irradiation with active energy rays is within the above range, the adhesive tape can be easily peeled off the substrate after irradiation with active energy rays. In this specification, the gel fraction of the adhesive tape refers to the value measured by the following method. <Method for measuring gel fraction> A 5cm x 5cm piece of adhesive tape, in which a release-treated polyester film is laminated to an adhesive layer, is cut to serve as a sample. Ultraviolet (UV) light (cumulative light intensity: 460mJ / cm²) is applied to the adhesive tape. 2 The substrate is irradiated with UV light (at 365 nm equivalent) from the substrate side, and then the peeled polyester film is removed from the sample. Next, approximately 0.1 parts by weight of the sample is cut out from the sample after UV irradiation. Then, the cut-out sample is wrapped in a drawstring shape with a porous polytetrafluoroethylene film (manufactured by Nitto Denko Corporation, trade name "Nitoflon (registered trademark) NTF1122", porosity 75%, thickness 85 μm) with an average pore size of 0.2 μm, whose weight has been measured in advance, and with string (Wg1), and the total weight (Wg2) is measured. Separately, the weight of the adhesive tape substrate is calculated from the area and the specific gravity of the substrate material (Wg3). This package is immersed in 50 mL of ethyl acetate and kept at room temperature (approximately 23°C) for 7 days to elute only the sol component in the adhesive layer from the film. Then, the package is removed from the ethyl acetate and the ethyl acetate adhering to the outer surface is wiped off. Next, the package is dried at 130°C for 2 hours, and the weight of the package (Wg4) is measured. The measured Wg1 to Wg4 are applied to the following formula to calculate the gel content of the adhesive layer. Gel fraction (%) = [(Wg4 - Wg1 - Wg3) / (Wg2 - Wg1 - Wg3)] If the substrate contains components that can dissolve in ethyl acetate (for example, additives such as plasticizers and antistatic agents), the gel fraction can be calculated using the following method. A 5cm x 5cm piece of adhesive tape, in which a release-treated polyester film is laminated to an adhesive layer, is cut to serve as a sample. Ultraviolet (UV) light (cumulative light intensity: 460mJ / cm²) is applied to the adhesive tape. 2(Converted to 365 nm) is irradiated from the substrate side, and then the polyester film that has been peeled off from the sample is peeled off. Next, about 0.1 part by weight of the adhesive layer is collected from the sample after ultraviolet irradiation. Then, a porous polytetrafluoroethylene film with an average pore diameter of 0.2 μm (manufactured by Nitto Denko Corporation, trade name "Nitflon (registered trademark) NTF1122", porosity 75%, thickness 85 μm) whose weight has been measured in advance and a taco thread (Wg A ) are used to wrap the adhesive layer from which the substrate has been peeled in a sachet shape, and the total weight (Wg B ) is measured. This package is immersed in 50 mL of ethyl acetate and held at room temperature (about 23 °C) for 7 days to elute only the sol component in the adhesive layer outside the film. Then, the package is taken out of the ethyl acetate and the ethyl acetate adhering to the outer surface is wiped off. Next, the package is dried at 130 °C for 2 hours, and the weight of the package (Wg c ) is measured. The measured Wg A ~Wg C is applied to the following formula to calculate the gel content of the adhesive layer. Gel content ratio (%) = [(Wg c - Wg A ) / (Wg2 - Wg1 - Wg3)]

[0012] The adhesive force of the adhesive tape after active energy ray irradiation is 0.04 N / 20 mm or less, preferably 0.03 N / 20 mm or less, and more preferably 0.02 N / 20 mm or less. If the adhesive force after active energy ray (for example, ultraviolet ray) irradiation is within the above range, an adhesive tape having light peelability can be obtained. The smaller the adhesive force after active energy ray (for example, ultraviolet ray) irradiation, the better. In this specification, the adhesive force of the adhesive tape after active energy ray irradiation refers to the adhesive force measured by the following method. The adhesive tape is washed with toluene, ethanol, and toluene in that order, dried, and bonded to a dried Si mirror wafer and stored at room temperature for 30 minutes. Then, UV is irradiated using a high-pressure mercury lamp (for example, manufactured by Nitto Seiki Co., Ltd., product name "UM-810") (integrated light amount 460 mJ / cm 2 ), and it refers to the adhesive force measured under the following conditions. <Adhesive force measurement conditions> Tensile speed: 300 mm / min Peeling angle: 180° Temperature: 23℃ Humidity: 50%RH Tape width: 20mm Tape length: 80mm

[0013] The adhesive tape has an adhesive strength of preferably 0.2 N / 20 mm or more, more preferably 1.0 N / 20 mm or more, and even more preferably 2.0 N / 20 mm or more before irradiation with active energy rays. If the adhesive strength before irradiation with active energy rays is within the above range, it will have sufficient adhesion to the adherend. The adhesive strength before irradiation with active energy rays is, for example, 20 N / 20 mm or less. In this specification, the adhesive strength of the adhesive tape before irradiation with active energy rays refers to the value measured by the following method: The adhesive tape is washed in toluene, ethanol, and toluene in that order, bonded to a dried Si mirror wafer, stored at room temperature for 30 minutes, and then the adhesive strength is measured under the following conditions. <Conditions for measuring adhesive strength> Tensile speed: 300 mm / min Peeling angle: 180° Temperature: 23℃ Humidity: 50%RH Tape width: 20mm Tape length: 80mm

[0014] The thickness of the adhesive tape in the embodiment of the present invention can be set to any suitable thickness. Preferably, the thickness of the adhesive tape is 30 μm to 400 μm, more preferably 40 μm to 300 μm, and even more preferably 50 μm to 200 μm.

[0015] A-2. Base material The base material can be composed of any suitable resin. Specific examples of resins constituting 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, fluorine resins, polyethers, polystyrene resins such as polystyrene; polycarbonate, polyethersulfone, and polyetheretherketone. Preferably, the resin is a polyolefin resin or a polyester resin. Since these resins transmit ultraviolet light, an adhesive layer can be formed using an ultraviolet-curing adhesive to provide an adhesive tape with easy peelability.

[0016] 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 antistatic agents. The type and amount of other components used can be any appropriate amount depending on the purpose.

[0017] The thickness of the substrate is preferably 30 μm to 200 μm, more preferably 40 μm to 180 μm, and even more preferably 45 μm to 180 μm.

[0018] A-3.Adhesive layer The adhesive layer of the adhesive tape in the embodiment of the present invention is formed of an active energy ray curable adhesive. Typical examples of active energy ray curable adhesives include ultraviolet curable adhesives. The active energy ray curable adhesive is preferably a water-dispersible adhesive. Preferably, the water-dispersible adhesive is an adhesive containing a water-dispersible acrylic polymer, an active energy ray curable resin, and a photopolymerization initiator. Using such an adhesive provides excellent adhesive strength and excellent adhesion to the adherend. Such an adhesive, while being a water-based adhesive composition, has excellent adhesive strength and can achieve both adhesion to the adherend and easy peelability. Therefore, it is possible to provide an adhesive that reduces environmental impact by reducing the amount of solvent used and can be suitably used in semiconductor wafer processing processes.

[0019] The Hansen solubility parameter (HSP) value distance between the water-dispersible acrylic polymer and the active energy ray-curable resin is preferably 8 or less, more preferably 7.5 or less, and even more preferably 7.0 or less. The distance between the HSP values ​​of the water-dispersible acrylic polymer and the active energy ray-curable resin is, for example, 0 or more. If the distance between the HSP values ​​of the water-dispersible acrylic polymer and the active energy ray-curable resin is within the above range, the compatibility between the water-dispersible acrylic polymer and the active energy ray-curable resin is good, the proportion of low molecular weight components present after active energy ray irradiation can be suppressed, and an easily peelable adhesive tape can be obtained. Furthermore, the residue of fine particles on the adherend can be suppressed, and particulate contamination of the adherend can be suppressed.

[0020] The Hansen solubility parameter is represented by a vector plotted in three-dimensional space, which divides the Hildebrand solubility parameter into three components: dispersion force (δd), permanent dipole intermolecular force (δp), and hydrogen bonding force (δh). Substances with similar vectors are judged to have high solubility towards each other. In other words, the similarity of solubility can be determined from the distance between their HSP values ​​(HSP value distance). The definition and calculation of the Hansen solubility parameter (HSP) are described in Charles M. Hansen's "Hansen Solubility Parameters: A Users Handbook" (CRC Press, 2007). There are known HSP values ​​for various resins and solvents, and these can be used as is, or values ​​calculated using the computer software HSPiP (Hansen Solubility Parameters in Practice) can be used. HSPiP also includes a database of resins and solvents.

[0021] The HSP values ​​of acrylic polymers and UV-curable resins for which the HSP value is not publicly known can be measured by the following method. The acrylic polymer or UV-curable resin to be measured is placed in a sealable container into approximately 20 different solvents with varying HSP values, at concentrations such that about half of the 20 solvents dissolve and about half remain insoluble. The container is then handshaked to thoroughly mix the acrylic polymer or UV-curable resin with the solvent. The container is then left to stand for 24 hours at room temperature (23°C). Afterward, the container is visually observed. If precipitate or aggregates are present in the container, it is considered insoluble; if no precipitate or aggregates are present, it is considered soluble. This test is performed for multiple solvents, and from the obtained test results, a sphere (Hansen sphere) is drawn in Hansen space that includes the coordinates of the solvent in which the target substance dissolved, but does not include the coordinates of the solvent in which the target substance did not dissolve. The obtained values ​​are entered into the calculation software described above, and the HSP values ​​of the acrylic polymer and UV-curable resin are calculated using the following formula. In this specification, HSP values ​​are calculated using cyclohexane, toluene, chloroform, 4-methyl-2-pentanone, ethyl acetate, cyclohexanone, 1,1,2,2-tetrabromoethane, acetone, N-methyl-2-pyrrolidone, benzyl alcohol, 1-butanol, acetic acid, 2-methoxyethanol, γ-butyrolactone, N,N-dimethylformamide, ethanol, N-methylformamide, ethanolamine, formamide, and 2-propanol. HSP value = √(δD^2 + δP^2 + δH^2)

[0022] Next, the dispersion force (δd) of the obtained acrylic polymer p ), permanent dipole intermolecular force (δp p ), and hydrogen bonding force (δh p ) and the dispersion force (δd) of the active energy ray curable resin. r ), permanent dipole intermolecular force (δp r ), and hydrogen bonding force (δh r The distance (Ra) between the HSP values ​​of the acrylic polymer and the active energy ray curable resin is calculated using the following formula. Ra=[4×(δds -δd ad ) 2 +(δp s -δp ad ) 2 +(δh s -δh ad ) 2 ] 1 / 2

[0023] A-3-1. Water-dispersible acrylic polymers Water-dispersible acrylic polymers (hereinafter also referred to as acrylic polymers) can be obtained by emulsion polymerization of any suitable monomer component in water. That is, water-dispersible acrylic polymers are emulsions of acrylic polymers. The average particle size of the acrylic polymer emulsion is preferably 80 nm to 400 nm, more preferably 100 nm to 300 nm, and even more preferably 100 nm to 200 nm. In this specification, the average particle size of water-dispersible acrylic polymers refers to the volume-based median diameter (D50) measured by laser diffraction-scattering.

[0024] In one embodiment, the water-dispersible acrylic polymer is preferably a polymer having a core-shell structure (hereinafter also referred to as a core-shell polymer). By using a water-dispersible acrylic polymer that is a core-shell polymer, an adhesive can be provided that has better adhesion before irradiation with active energy rays and can achieve both adhesion to the adherend and easy peelability.

[0025] A water-dispersible acrylic polymer, which is a core-shell polymer, can be obtained by stepwise emulsion polymerization of any suitable monomer components. For example, it can be obtained by so-called seed polymerization, in which a monomer composition forming the core is emulsion polymerized in any suitable method, and then a monomer composition forming the shell is emulsion polymerized in the presence of polymer particles that will form the core.

[0026] The core-shell polymer, a water-dispersible acrylic polymer, preferably has a core ratio of 5% by weight or more, more preferably 10% by weight or more. If the weight ratio of the core portion to the shell portion is within the above range, a water-dispersible adhesive composition can be provided that has excellent adhesive strength and can achieve both adhesion to the adherend and easy peelability.

[0027] The core-shell polymer preferably comprises a shell portion having a glass transition temperature Tg of -10°C or higher, and a core portion having a glass transition temperature Tg of less than -10°C. Using such a core-shell polymer, an adhesive tape can be obtained that has excellent adhesion before irradiation with active energy rays and can be peeled off without damaging the adherend after irradiation with active energy rays.

[0028] The glass transition temperature Tg of the shell portion is preferably -10°C or higher, more preferably -5°C or higher, and even more preferably 0°C or higher. The glass transition temperature Tg of the shell portion is, for example, 50°C or lower. The glass transition temperature Tg of the core portion is preferably less than -10°C, more preferably -20°C or lower, even more preferably -30°C or lower, and particularly preferably -35°C or lower. The glass transition temperature Tg of the core portion is, for example, -60°C or higher. If the glass transition temperatures Tg of the core portion and the shell portion are within the above ranges, an adhesive tape can be provided that has good adhesion before irradiation with active energy rays and good peelability after irradiation with active energy rays.

[0029] In this specification, the glass transition temperature of a water-dispersible acrylic polymer refers to the theoretical value calculated using Fox's formula from the monomer units constituting each polymer and their proportions. The theoretical glass transition temperature obtained from Fox's formula may coincide with the measured glass transition temperature obtained by methods such as differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement. As described later, if the theoretical value cannot be calculated, the measured glass transition temperature may be used.

[0030] Fox's equation, as shown below, is a relationship between the Tg of an acrylic polymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the acrylic polymer. 1 / Tg = Σ(Wi / Tgi) (In the formula, Tg represents the glass transition temperature of the acrylic polymer (unit: K), Wi represents the weight fraction of monomer i in the acrylic polymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K)).

[0031] The glass transition temperature of the homopolymer used to calculate Tg can be any value found in any appropriate source. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of those monomers. 2-Ethylhexyl Acrylate -70℃ Methyl methacrylate 8℃ Acrylic acid 106℃ 2-Acryloyloxyethyl succinate -40℃ 4-Hydroxybutyl acrylate -40℃ N-acryloylmorpholine 145℃ Butyl acrylate -55℃ Ethyl acrylate -20℃ 2-hydroxyethyl acrylate -15℃

[0032] For the glass transition temperatures of monomer homopolymers other than those exemplified above, you can use the values ​​listed in, for example, the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). If multiple values ​​are listed, the highest value should be used.

[0033] For monomers whose glass transition temperature for homopolymers is not listed in the Polymer Handbook, the values ​​obtained by the measurement method described in Japanese Patent Publication No. 2007-51271 can be used. Specifically, 100 parts by weight of monomer, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent are added to a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, and the mixture is stirred for 1 hour while circulating nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Then, it is cooled to room temperature to obtain a homopolymer solution with a solid content of 33% by weight. Next, this homopolymer solution is cast onto a release liner and dried to produce a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. This test sample is punched out into a 7.9 mm diameter disc shape, sandwiched between parallel plates, and measured using a viscoelasticity tester (ARES, Rheometrics) in shear mode while applying a shear strain at a frequency of 1 Hz, within a temperature range of -70°C to 150°C and a heating rate of 5°C / min. The peak top temperature of tanδ is defined as the Tg of the homopolymer.

[0034] A-3-1-1. Monomer components The monomer compositions used to form the core and shell can be adjusted to form a core or shell having any suitable glass transition temperature. For example, monomers can be selected to form a core or shell having a designed glass transition temperature Tg based on Fox's formula, and then emulsion polymerization can be performed.

[0035] Any suitable acrylic monomer can be used as the monomer component. Typical monomer components include alkyl (meth)acrylates. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth) Examples of C1-20 alkyl esters of (meth)acrylate include nonyl 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. Alkyl (meth)acrylate may be used alone or in combination of two or more. In this specification, (meth)acrylic means acrylic and / or methacrylic.

[0036] The monomer composition may further contain any other suitable monomer copolymerizable with alkyl (meth)acrylate. For example, carboxyl group-containing monomers such as acrylic acid and methacrylic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and hydroxyalkyl (meth)acrylate; sulfonic acid group-containing monomers such as styrene sulfonic acid and allyl sulfonic acid; (N-substituted) amide monomers such as diacetone acrylamide, (meth)acrylamide, and N,N-dimethyl(meth)acrylamide; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate; (meth)acrylic Examples include alkoxyalkyl monomers of (meth)acrylate such as methoxyethyl acid; maleimide monomers such as N-cyclohexyl maleimide and N-isopropyl maleimide; itaconimide monomers such as N-methylitaconimide and N-ethylitaconimide; 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 heterocyclic rings, 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.By including these monomer components, properties such as cohesiveness, heat resistance, and crosslinking can be modified. These monomer components may be used individually or in combination of two or more.

[0037] In one embodiment, it is preferable to use an amide group-containing monomer as the monomer component constituting the shell portion. Specific examples of amide group-containing monomers include acrylamide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. Preferably, the monomer is N-(meth)acryloylmorpholine, N,N-diethyl(meth)acrylamide, or N-isopropylacrylamide, and more preferably N-acryloylmorpholine. Using an amide group-containing monomer as the monomer used in polymerization of the shell portion can improve the initial tackiness of the adhesive layer. The content of the amide group-containing monomer in the total monomers constituting the shell portion is, for example, 0.01% to 10% by weight, and preferably 0.1% to 7% by weight.

[0038] In one embodiment, the acrylic polymer is preferably a polymer obtained by polymerizing a monomer composition containing a carboxyl group-containing monomer represented by formula (1) as a monomer component. When the acrylic polymer is a core-shell polymer, the carboxyl group-containing monomer represented by formula (1) may be contained only in the monomer composition used for polymerization of the core portion, or only in the monomer composition used for polymerization of the shell portion, or in both the monomer composition used for polymerization of the core portion and the monomer composition used for polymerization of the shell portion. Only one carboxyl group-containing monomer may be used, or two or more may be used in combination. [ka] (In the formula, R 1 R represents a hydrogen atom or a methyl group. 2 (where represents a divalent hydrocarbon group, x represents an integer from 1 to 20, and y represents 0 or 1).

[0039] R 1 x represents a hydrogen atom or a methyl group. x is an integer from 1 to 20, preferably from 1 to 10, and more preferably from 1 to 8. y is 0 or 1. R 2 R represents a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include saturated aliphatic hydrocarbon groups such as alkylene groups, saturated alicyclic hydrocarbon groups such as cycloalkylene groups, aromatic hydrocarbon groups such as phenylene groups, unsaturated aliphatic hydrocarbon groups, or unsaturated alicyclic hydrocarbon groups. Preferably, R 2 x is a linear or branched alkylene group or cycloalkylene group, more preferably a linear or branched alkylene group or cycloalkylene group having 1 to 20 carbon atoms, and even more preferably a linear or branched alkylene group or cycloalkylene group having 1 to 10 carbon atoms. x is within the above range, and R 2 If the group is a divalent hydrocarbon group as described above, an adhesive with excellent dispersion stability and coating properties can be obtained.

[0040] Examples of carboxyl group-containing monomers represented by formula (1) include 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, ω-carboxy-polycaprolactone (n≒2) monoacrylate, and 2-methacryloyloxyethyl hexahydrophthalic acid.

[0041] Commercially available monomers may be used as the carboxyl group-containing monomer represented by formula (1). Examples of commercially available products include the trade names "HOA-MS," "Light Ester HO-MS(N)," and "Light Acrylate HOA-HH(N)" from Kyoeisha Chemical Co., Ltd., and "Aronics M-5300" from Toagosei Co., Ltd.

[0042] The content of the carboxyl group-containing monomer represented by formula (1) is preferably 3 to 30 parts by weight, more preferably 4 to 25 parts by weight, even more preferably 4 to 20 parts by weight, and particularly preferably 6 to 15 parts by weight, per 100 parts by weight of the monomer component (in the case of a core-shell polymer, the monomer component used for polymerization of the core or the monomer component used for polymerization of the shell). If the content of the carboxyl group-containing monomer represented by formula (1) is within the above range, an adhesive with excellent dispersion stability and coating properties can be obtained.

[0043] A-3-2. Surfactants Any suitable surfactant can be used as the surfactant. Preferably, a reactive surfactant can be used. Reactive surfactants have the function of a surfactant as well as radical polymerizable functional groups in their molecules (for example, radical reactive groups such as ethenyl groups, propenyl groups, allyl groups, and allyl ether groups). By using a reactive surfactant, contamination of the adherend by the adhesive using a water-dispersible acrylic polymer can be reduced, and the adhesive strength of the adhesive composition before irradiation treatment can be improved. In addition, the water resistance of the adhesive tape (e.g., the adhesive layer) using the adhesive composition can be improved, and peeling of the adhesive tape can be suppressed even when water is applied during processing.

[0044] Examples of reactive surfactants include surfactants into which any suitable surfactant (e.g., anionic surfactants, nonionic surfactants, etc.) has been modified by introducing radical polymerizable functional groups (radical reactive groups) such as propenyl groups and allyl ether groups. Reactive surfactants have radical polymerizable functional groups related to ethylenically unsaturated double bonds, and compared to non-reactive surfactants, they can reduce the saturation water absorption rate of the formed adhesive layer. Furthermore, from the viewpoint of the stability of the aqueous dispersion and the durability of the adhesive layer, a single reactive surfactant may be used, or two or more may be used in combination.

[0045] Specific examples of anionic surfactants include higher fatty acid salts such as sodium oleate; alkylaryl sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene alkyl ether sulfate salts such as sodium polyoxyethylene lauryl ether sulfate; polyoxyethylene alkylaryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; alkyl sulfosuccinate salts and their derivatives such as sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, and sodium polyoxyethylene lauryl sulfosuccinate; and polyoxyethylene distyrenated phenyl ether sulfate salts. Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, and sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene higher fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monostearate; glycerin higher fatty acid esters such as oleic acid monoglyceride and stearate monoglyceride; polyoxyethylene polyoxypropylene block copolymer and polyoxyethylene distyrenated phenyl ether.

[0046] A commercially available product may be used as the reactive surfactant. Specific examples of anionic reactive surfactants include alkyl ether reactive surfactants such as "Aqualon KH-05", "Aqualon KH-10", and "Aqualon KH-20" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "Adekarya Soap SR-10N" and "Adekarya Soap SR-20N" manufactured by Asahi Denka Kogyo Co., Ltd., and "Latemul PD-104" manufactured by Kao Corporation; sulfosuccinate ester reactive surfactants such as "Latemul S-120", "Latemul S-120A", "Latemul S-180P", and "Latemul S-180A" manufactured by Kao Corporation, and "Eleminol JS-20" manufactured by Sanyo Chemical Industries, Ltd.; and "Aqualon H-2855A", "Aqualon H-3855B", "Aqualon H-3855C", "Aqualon H-3856", "Aqualon HS-05", "Aqualon HS-10", "Aqualon HS-20", and "Aqualon H" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Examples of alkylphenyl ether-based or alkylphenyl ester-based reactive surfactants include "S-30", "Aqualon BC-05", "Aqualon BC-10", "Aqualon BC-20", and Asahi Denka Kogyo Co., Ltd.'s product names "Adekarya Soap SDX-222", "Adekarya Soap SDX-223", "Adekarya Soap SDX-232", "Adekarya Soap SDX-233", "Adekarya Soap SDX-259", "Adekarya Soap SE-10N", and "Adekarya Soap SE-20N"; (meth)acrylate sulfate-based reactive surfactants include Nippon Emulsifier Co., Ltd.'s product names "Antox MS-60" and "Antox MS-2N", and Sanyo Chemical Industries, Ltd.'s product name "Eleminol RS-30"; and phosphate ester-based reactive surfactants include Daiichi Kogyo Seiyaku Co., Ltd.'s product name "H-3330PL" and Asahi Denka Kogyo Co., Ltd.'s product name "Adekarya Soap PP-70".Specific examples of nonionic reactive surfactants include alkyl ether reactive surfactants such as "Adekaria Soap ER-10," "Adekaria Soap ER-20," "Adekaria Soap ER-30," and "Adekaria Soap ER-40" manufactured by Asahi Denka Kogyo Co., Ltd., and "Latemul PD-420," "Latemul PD-430," and "Latemul PD-450" manufactured by Kao Corporation; alkylphenyl ether or alkylphenyl ester reactive surfactants such as "Aqualon RN-10," "Aqualon RN-20," "Aqualon RN-30," and "Aqualon RN-50" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and "Adekaria Soap NE-10," "Adekaria Soap NE-20," "Adekaria Soap NE-30," and "Adekaria Soap NE-40" manufactured by Asahi Denka Kogyo Co., Ltd.; and (meth)acrylate sulfate ester reactive surfactants such as "RMA-564," "RMA-568," and "RMA-1114" manufactured by Nippon Emulsifier Co., Ltd.

[0047] Anionic reactive surfactants are preferably used as the reactive surfactant. Anionic reactive surfactants often have excellent polymerization stability and are preferred from the viewpoint of particle stability and appearance. Anionic reactive surfactants and nonionic reactive surfactants may also be used in combination.

[0048] In one embodiment, the reactive surfactant is preferably SO4 2- The ion concentration is 100 μg / g or less. Furthermore, the reactive surfactant is preferably an ammonium salt type surfactant. The adhesive tape of the embodiment of the present invention may be an adhesive tape used in the semiconductor wafer processing process. Therefore, impurity ions contained in the adhesive can be a problem. For this reason, it is preferable that the adhesive contains a small amount of impurity ions. SO4 2- If the ion concentration is within the above range and an ammonium salt type surfactant is used, the adverse effects of impurity ions can be suppressed. Any appropriate method can be used to reduce or remove impurity ions, such as the ion exchange resin method, membrane separation method, or impurity precipitation filtration method using alcohol.

[0049] The reactive surfactant is used in any appropriate amount. Preferably, the reactive surfactant is in the amount of 0.1 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight, per 100 parts by weight of the monomer composition. If the reactive surfactant content exceeds 5 parts by weight per 100 parts by weight of the monomer composition, when the adhesive composition is used as an adhesive tape for semiconductor wafer processing, there is a risk that the element fragments will peel off from the adhesive tape during the dicing process or subsequent processes. Also, if the reactive surfactant content is less than 0.1 parts by weight per 100 parts by weight of the monomer composition, there is a risk that a stable emulsified state cannot be maintained.

[0050] Furthermore, a reactive surfactant may be used in combination with a surfactant that does not have a radical polymerizable functional group. Examples of surfactants that do not have a radical polymerizable functional group include anionic surfactants such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and sodium polyoxyethylene alkyl sulfosuccinate, as well as nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene polyoxypropylene block polymer. These surfactants may be used individually or in combination of two or more.

[0051] A-3-3. Polymerization method for water-dispersible acrylic polymers Water-dispersible acrylic polymers can be polymerized by any suitable method. For example, a water-dispersible acrylic polymer can be obtained by adding and mixing water (such as deionized water), a monomer composition, a surfactant, a polymerization initiator, and any additives in a reaction vessel and carrying out emulsion polymerization. If the water-dispersible acrylic polymer is a core-shell polymer, for example, polymer particles that form the core can be formed by adding and mixing a monomer composition containing monomers that form the core, water, a surfactant, a polymerization initiator, and any additives in a reaction vessel and carrying out emulsion polymerization, and then forming the shell by adding and mixing a monomer composition containing monomers that form the shell, water, a surfactant, a polymerization initiator, and any additives in a reaction vessel and carrying out emulsion polymerization, thereby obtaining a water-dispersible acrylic polymer that is a core-shell polymer. Examples of optional additives include chain transfer agents and silane coupling agents.

[0052] Any suitable polymerization initiator can be used as the polymerization initiator. For example, azo polymerization initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutylamidine); persulfates such as potassium persulfate and ammonium persulfate; and benzoyl persulfate. Examples include peroxide-based polymerization initiators such as oxides, t-butyl hydroperoxide, and hydrogen peroxide; and redox-based initiators formed by combinations of peroxides and reducing agents [for example, combinations of peroxides and ascorbic acid (e.g., hydrogen peroxide solution and ascorbic acid), combinations of peroxides and iron(II) salts (e.g., hydrogen peroxide solution and iron(II) salt), and redox-based polymerization initiators formed by combinations of persulfates and sodium bisulfite]. A single polymerization initiator may be used, or two or more may be used in combination.

[0053] The polymerization initiator can be used in any appropriate amount depending on the type of polymerization initiator used and the composition of the monomer composition. The content of the polymerization initiator is, for example, 0.01 parts by weight to 1 part by weight, preferably 0.02 parts by weight to 0.5 parts by weight, per 100 parts by weight of the monomer composition.

[0054] Chain transfer agents can be used, for example, to adjust the molecular weight of water-dispersible acrylic polymers. Any suitable chain transfer agent can be used. Specifically, examples include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. One chain transfer agent may be used alone, or two or more may be used in combination. The content of the chain transfer agent is usually 0.001 to 0.5 parts by weight per 100 parts by weight of the monomer composition.

[0055] Water-dispersible acrylic polymers are obtained by emulsion polymerization of a monomer composition, a reactive surfactant, a polymerization initiator, and any additives such as a chain transfer agent. Therefore, water-dispersible acrylic polymers can be prepared in the form of an emulsion. Any suitable method can be used for emulsion polymerization. Specifically, examples include emulsion polymerization methods using a general batch preparation method (batch polymerization method), a monomer dropwise addition method, and a monomer emulsion dropwise addition method. When adding monomers dropwise, they may be added continuously or in portions. The polymerization temperature can be set to any suitable value depending on the type of polymerization initiator, for example, it may be set in the range of 5°C to 100°C. Furthermore, it is preferable to add an alkaline aqueous solution such as ammonia water, various water-soluble amines, sodium hydroxide aqueous solution, or potassium hydroxide aqueous solution to the solution of the water-dispersible acrylic polymer obtained by emulsion polymerization to adjust the pH to, for example, 6 to 11, preferably 7 to 10.

[0056] The gel fraction of the water-dispersible acrylic polymer is preferably 50% by weight or more, and more preferably 70% by weight or more. If the gel fraction of the water-dispersible acrylic polymer is less than 50% by weight, the adhesive strength does not decrease easily after irradiation with active energy rays, and contamination of the adherend by the sol component is likely to occur. The gel fraction of the water-dispersible acrylic polymer is, for example, 99% by weight or less. The gel fraction of the water-dispersible acrylic polymer can be determined by any suitable method. For example, the gel fraction can be determined as the insoluble content in a solvent such as ethyl acetate, and specifically, it can be determined as the weight fraction (unit: wt%) of the insoluble component after immersing the water-dispersible acrylic polymer in ethyl acetate at 23°C for 7 days, relative to the sample before immersion.

[0057] A-3-4. Active energy ray curable resins As the active energy ray curable resin, any suitable resin that can be cured by active energy rays such as ultraviolet light can be used. Specifically, an active energy ray curable resin having an HSP value distance of 8 or less from the acrylic polymer used in the adhesive is preferably used. As the active energy ray curable resin, an ultraviolet curable resin is preferably used. As the ultraviolet curable resin, for example, an ultraviolet curable monomer and / or oligomer can be used. Examples of ultraviolet curable monomers include urethane (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, 1,4-butanediol di(meth)acrylate, etc. The urethane (meth)acrylate may be a self-emulsifying urethane (meth)acrylate. Examples of UV-curable oligomers include urethane oligomers, polyether oligomers, polyester oligomers, polycarbonate oligomers, and polybutadiene oligomers. Preferably, the oligomers used have a molecular weight of approximately 100 to 30,000. Monomers and oligomers may be used individually or in combination of two or more. The active energy ray-curable resin may be emulsified using any suitable surfactant or self-emulsifying urethane (meth)acrylate as needed. Emulsification facilitates the preparation of water-dispersible adhesives.

[0058] The active energy ray curable resin is preferably urethane (meth)acrylate. Urethane (meth)acrylate has good compatibility with (meth)acrylic polymers that can be used as the base polymer of adhesives, and tends to have a low glass transition temperature. Using urethane (meth)acrylate can further improve the adhesive strength before active energy ray irradiation. As an active energy ray curable resin, one is known to be an emulsified polyfunctional monomer with urethane (meth)acrylate. In embodiments of the present invention, it is preferable that the content of urethane (meth)acrylate relative to the total amount of active energy ray curable resin is higher. The content of urethane (meth)acrylate relative to the total amount of active energy ray curable resin is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, even more preferably 95% by weight or more, and particularly preferably 98% by weight or more. In one embodiment, the content of urethane (meth)acrylate relative to the total amount of active energy ray curable resin may be 100% by weight. Polyfunctional monomers are low molecular weight components, and if there are many polyfunctional monomers, they may not contribute to curing by active energy rays (e.g., ultraviolet light) and may remain as residual monomers. Residual polyfunctional monomers are easily transferred to the substrate and can cause contamination. Urethane (meth)acrylate has a high molecular weight, and even if it remains without contributing to curing by active energy rays, its transfer to the substrate can be suppressed.

[0059] Commercially available active energy ray curable resins may be used. Examples include "Shiko (registered trademark) UT-7119" from Mitsubishi Chemical Corporation, "WUA-2" from Daiichi Kogyo Seiyaku Co., Ltd., and "ETERNACOLL UW-9102" from UBE Corporation. Alternatively, "Shiko (registered trademark) UT-7119" from Mitsubishi Chemical Corporation, which is a commercially available product containing an active energy ray curable resin and a photopolymerization initiator, may be used. These active energy ray curable resins may also be selected if their HSP value distance to the acrylic polymer used as an adhesive is 8 or less.

[0060] The active energy ray curable resin can be used in any appropriate amount depending on the type of water-dispersible acrylic polymer, etc. For example, it is preferably 5 to 200 parts by weight, more preferably 20 to 150 parts by weight, and even more preferably 50 to 150 parts by weight, per 100 parts by weight of the water-dispersible acrylic polymer.

[0061] A-3-5. Photopolymerization Initiators Any suitable initiator can be used as the photopolymerization initiator. Examples of photopolymerization initiators include: acylphosphine oxide-based photopolymerization initiators such as ethyl 2,4,6-trimethylbenzylphenylphosphine and (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and benzyldimethyl ketal. Examples include ketal compounds such as 2-naphthalenesulfonyl chloride; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonates; and α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1. A single photopolymerization initiator may be used, or two or more may be used in combination. Preferably, a liquid photopolymerization initiator at room temperature (e.g., 23°C) is used, as it can dissolve (become compatible) in a water-dispersible acrylic polymer solution.

[0062] Commercially available photopolymerization initiators may be used. Examples include IGM Resins products such as Omnirad 127D, Omnirad TPO-L, Omnirad TPO, Omnirad 651, Omnirad 184, and Omnirad 500.

[0063] The photopolymerization initiator can be used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight, per 100 parts by weight of the water-dispersible acrylic polymer. If the content of the photopolymerization initiator is less than 0.5 parts by weight, the polymer may not cure sufficiently when irradiated with active energy rays. If the content of the photopolymerization initiator exceeds 20 parts by weight, the storage stability of the water-dispersible adhesive composition may decrease.

[0064] A-3-6. Crosslinking agents In one embodiment, the adhesive composition may further contain a crosslinking agent. By using a crosslinking agent, the gel fraction of the adhesive composition can be adjusted. Any suitable crosslinking agent can be used. Examples include bifunctional or higher epoxy crosslinking agents, isocyanate crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, melamine resin crosslinking agents, metal chelate crosslinking agents, peroxide crosslinking agents, and hydrazine crosslinking agents. Only one type of crosslinking agent may be used, or two or more types may be used in combination.

[0065] Specifically, crosslinking agents include epoxy crosslinking agents such as N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane, and 1,6-hexanediol diglycidyl ether; isocyanate crosslinking agents such as tolylene diisocyanate (blocked) (including blocked isocyanate crosslinking agents); carbodiimide crosslinking agents such as the product name "Carbodilite V-01 (manufactured by Nisseibo Co., Ltd.)"; epoxy crosslinking agents such as polyethylene glycol diglycidyl ether and polyglycerol polyglycidyl ether; and water-dispersible isocyanate crosslinking agents such as the product name "Elastron BN-69 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)". Examples of crosslinking agents include: oxazoline-based crosslinking agents such as "Epocross WS-500 (manufactured by Nippon Shokubai Co., Ltd.)"; aziridine-based crosslinking agents such as "Chemitite PZ-33 (manufactured by Nippon Shokubai Co., Ltd.)"; hydrophilized carbodiimide-based crosslinking agents such as "Carbodilite V-02" and "Carbodilite V-04 (manufactured by Nisshinbo Co., Ltd.)"; crosslinking agents containing active methylol groups or active alkoxymethyl groups such as active methylol such as hexamethylmelamine and active alkoxymethyl such as hexamethoxymethylmelamine; metal chelating crosslinking agents such as "Orgatic AI135 (manufactured by Matsumoto Pharmaceutical Co., Ltd.)"; and hydrazine-based crosslinking agents such as adipic acid dihydrazide and phthalate dihydrazide.

[0066] The crosslinking agent content is, for example, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight, per 100 parts by weight of the acrylic polymer. As described above, the water-dispersible adhesive composition does not need to contain a crosslinking agent (i.e., the crosslinking agent content may be 0 parts by weight).

[0067] A-3-7. Additives The adhesive may contain any suitable additives as needed. Examples of additives include catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, antioxidants, conductive materials, UV absorbers, light stabilizers, release modifiers, softeners, flame retardants, and solvents. Additives are used in any appropriate amount depending on the purpose.

[0068] The thickness of the adhesive layer can be set to any appropriate value. Preferably, the thickness of the adhesive layer is 2 μm to 200 μm, more preferably 3 μm to 150 μm, and even more preferably 5 μm to 100 μm. If the thickness of the adhesive layer is within the above range, it can exhibit sufficient adhesion to the adherend.

[0069] B. Method for manufacturing adhesive tape The adhesive tape according to the embodiment of the present invention can be manufactured by any suitable method. For example, it can be obtained by applying an adhesive to a release liner, drying it to form an adhesive layer on the release liner, and then transferring the adhesive layer to a substrate. Alternatively, the adhesive tape can be obtained by applying an adhesive to a substrate and drying it. Various methods can be used to apply the adhesive, such as bar 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. Any suitable drying method can be used.

[0070] C. Uses of adhesive tape The adhesive tape of the embodiment of the present invention can be suitably used in the manufacturing process of semiconductor wafers. For example, it can be used as a dicing tape and a backgrinding tape. As described above, the adhesive tape of the embodiment of the present invention can appropriately hold the adherend before irradiation with active energy rays, and after irradiation with active energy rays, the adhesive tape can be peeled off without damaging the adherend, even if the adherend is fine and / or thin. Therefore, it can be suitably used for processing semiconductor wafers that are thinner and have more complex structures. [Examples]

[0071] 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.

[0072] [Synthesis Example 1] Synthesis of Acrylic Polymer A In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirring device, 180 parts by weight of water, 58 parts by weight of 2-ethylhexyl acrylate (2EHA), 27 parts by weight of methyl methacrylate (MMA), 10 parts by weight of carboxyl group-containing monomer (HOA-MS) (2-acryloyloxyethyl succinic acid, manufactured by Kyoeisha Chemical Co., Ltd., trade name "HOA-MS"), 5 parts by weight of 4-hydroxybutyl acrylate (4HBA) (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "4HBA"), and 5 parts by weight of reactive surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Aqualon KH-1025") were mixed and emulsified by stirring with a homomixer. Then, the mixture was purged with nitrogen for 1 hour while stirring. Thereafter, the internal bath temperature was controlled to 60°C during polymerization. To this, 0.02 parts by weight of a water-soluble azo initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "VA-057") was added to initiate polymerization, and the mixture was heated for 2 hours to produce the core. Next, 180 parts by weight of water, 24 parts by weight of 2EHA, 56 parts by weight of MMA, 10 parts by weight of HOA-MS, 5 parts by weight of 4HBA, 5 parts by weight of acryloylmorpholine (ACMO), and 0.71 parts by weight of a reactive surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Aqualon KH-1025") were mixed and stirred with a homomixer to prepare a monomer emulsion for the shell. 0.10 parts by weight of a water-soluble azo initiator (manufactured by Fujifilm Wako Pure Chemical Industries, trade name "VA-057") was added to the aqueous dispersion containing the dispersed core particles. After a 10-minute induction period, the emulsified monomer emulsion solution for the shell was added over 2 hours, and a further 2-hour maturation reaction was carried out to produce a core-shell type aqueous dispersion acrylic polymer A.

[0073] [Synthesis Examples 2 and 3] Synthesis of Acrylic Polymers B and C Core-shell type water-dispersible acrylic polymers B and C were obtained in the same manner as in Synthesis Example 1, except that the monomer compositions of the core and shell portions were changed as shown in Table 1.

[0074] [Synthesis Example 4] Synthesis of Acrylic Polymer D A monomer composition was obtained by mixing the monomer components listed in Table 1, 218 parts by weight of solvent (ethyl acetate), and 0.3 parts by weight of BPO paste-N (manufactured by NOF Corporation, trade name "Niper BW"). 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 was purged at room temperature for 1 hour while stirring. Subsequently, polymerization was carried out at 65°C for 4 hours while stirring under nitrogen inflow, and then at 75°C for 2 hours to obtain a resin solution (prepolymer). Next, the obtained resin solution was cooled to room temperature. Then, 42.6 parts by weight of 2-isocyanatoethyl methacrylate (manufactured by Showa Denko, trade name "Karens MOI"), a compound having a polymerizable carbon-carbon double bond, was added to the resin solution. Furthermore, 0.22 parts by weight of dibutyltin IV dilaurate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred at 50°C for 24 hours under an air atmosphere. After that, ethyl acetate was added to obtain acrylic polymer D (solid content 30%).

[0075] [Table 1]

[0076] [Example 1] 100 parts by weight of water-dispersible acrylic polymer A, 140 parts by weight of UV-curing resin (manufactured by Mitsubishi Chemical Corporation, trade name "Shiko (registered trademark) UT-7119"), and 3 parts by weight of photopolymerization initiator (manufactured by IGM Resins, trade name "OmniradTPO-L") were added and mixed, then neutralized with 10% aqueous ammonia to obtain a water-dispersible adhesive composition. The obtained water-dispersible adhesive composition was applied to the silicone-released surface of a polyester film (thickness 38 μm) that had undergone a silicone-release treatment, so that the thickness after drying was 10 μm. It was then dried at 125°C for 3 minutes to form an adhesive layer. Next, a substrate (manufactured by Mitsubishi Chemical Corporation, product name "T912E50" (easy-adhesion polyethylene terephthalate (PET) film (thickness 50 μm))) was laminated to the adhesive surface of the adhesive layer, and the adhesive layer was transferred to produce an adhesive tape.

[0077] [Examples 2-4] An adhesive tape was obtained in the same manner as in Example 1, except that the composition of the adhesive composition was changed as shown in Table 2.

[0078] (Comparative Examples 1-3) An adhesive tape was obtained in the same manner as in Example 1, except that the composition of the adhesive composition was changed as shown in Table 2.

[0079] (Comparative Example 4) A sticky adhesive composition was obtained by mixing 100 parts by weight of solids of acrylic polymer D, 3 parts by weight of a crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101-A"), 0.2 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad 127D"), 1.6 parts by weight of additive 1 (manufactured by NOF Corporation, trade name "Modiper® AS100"), and 0.2 parts by weight of additive 2 (manufactured by NOF Corporation, trade name "Uniol D-1200"). An adhesive tape was obtained in the same manner as in Example 1, except that the obtained adhesive composition was used instead of the aqueous adhesive composition.

[0080] <Rating> The following evaluations were performed using the water-dispersible acrylic polymers used in the examples and comparative examples, and the resulting adhesive tapes. The results are shown in Table 2. 1. Glass transition temperature The glass transition temperatures of the water-dispersible acrylic polymers obtained in Synthesis Examples 1-3 were calculated using Fox's equation below. 1 / Tg = Σ(Wi / Tgi) (In the formula, Tg represents the glass transition temperature of the acrylic polymer (unit: K), Wi represents the weight fraction of monomer i in the acrylic polymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K)). The following values ​​were used for the glass transition temperatures of the monomer homopolymers. 2-Ethylhexyl Acrylate -70℃ Methyl methacrylate 8℃ 2-Acryloyloxyethyl succinate -40℃ 4-Hydroxybutyl acrylate -40℃ N-acryloylmorpholine 145℃ Butyl acrylate -55℃ Ethyl acrylate -20℃ 2-hydroxyethyl acrylate -15℃

[0081] 2. Gel fraction The adhesive tape obtained in the examples or comparative examples was cut into 5cm x 5cm pieces and used as a sample. The adhesive tape was exposed to ultraviolet (UV) light (cumulative light intensity: 460mJ / cm²). 2 The sample was irradiated with UV light (at 365 nm) from the substrate side, and then the peeled polyester film was removed from the sample. Next, approximately 0.1 parts by weight of the sample was cut out from the sample after UV irradiation. Then, the cut-out sample was wrapped in a drawstring shape with a porous polytetrafluoroethylene film (manufactured by Nitto Denko Corporation, trade name "Nitoflon (registered trademark) NTF1122", porosity 75%, thickness 85 μm) with an average pore size of 0.2 μm, whose weight had been measured in advance, and with string (Wg1), and the total weight (Wg2) was measured. Separately, the weight of the adhesive tape substrate was calculated from the area and the specific gravity of the substrate material (Wg3). This package was immersed in 50 mL of ethyl acetate and kept at room temperature (approximately 23°C) for 7 days to elute only the sol component in the adhesive layer from the film. Then, the package was removed from the ethyl acetate and the ethyl acetate adhering to the outer surface was wiped off. Next, the package was dried at 130°C for 2 hours, and the weight of the package (Wg4) was measured. The gel content of the adhesive layer was calculated by applying the measured Wg1 to Wg4 values ​​to the following formula. Gel fraction (%) = [(Wg4 - Wg1 - Wg3) / (Wg2 - Wg1 - Wg3)]

[0082] 3. Measurement of the molecular weight of the sol component The soluble components collected during gel fraction measurement were entirely collected in a screw-cap tube. The soluble solution in the screw-cap tube was then left at room temperature and air-dried. Afterward, tetrahydrofuran (THF) was added to the screw-cap tube until the remaining solid content was 3.3 g / L, and the solution was allowed to stand for 1 day to dissolve. This solution was filtered through a syringe filter, and the molecular weight of the soluble components (sol) was measured by GPC under the following conditions, creating a molecular weight curve. The area ratio of weight-average molecular weight (Mw) less than or equal to 1000 was calculated within the obtained molecular weight curve. Measurement conditions: Sample volume 500 mg, column temperature 40°C, flow rate 1.0 mL / min Equipment: Manufactured by Tosoh Corporation, product name "HLC 8320GPC" Column: TSKgel GMHHR-H(S)

[0083] 4. Adhesive strength Si mirror wafers (manufactured by Shin-Etsu Chemical Co., Ltd.) were pre-treated by washing and drying them in the order of toluene, ethanol, and toluene. Next, the adhesive layer of the adhesive tape for each example or comparative example was attached to the wafer and stored at room temperature for 30 minutes. After that, the adhesive strength was measured under the following conditions (adhesion strength before UV). Similarly, adhesive tape was attached to the wafer, and the substrate side of the adhesive tape was exposed to high-pressure mercury lamp (UV irradiance 70 mW / cm²). 2 (Manufactured by Nitto Seiki Co., Ltd., product name: UM-810) UV irradiation for approximately 10 seconds (cumulative light intensity 460 mJ / cm²) 2 The device was then irradiated with UV light. Subsequently, the adhesive strength was measured under the following conditions (adhesion strength after UV light). <Conditions for measuring adhesive strength> Tensile speed: 300 mm / min Peeling angle: 180° Temperature: 23℃ Humidity: 50%RH Tape width: 20mm Tape length: 80mm

[0084] 5. Particle Measurement In a clean bench, the polyester film was peeled off from the adhesive tape obtained in the examples or comparative examples, and the adhesive layer side of the adhesive tape was attached to an unused silicon mirror wafer (6 inches). It was then stored for 30 minutes. After that, the substrate side of the adhesive tape was exposed to a high-pressure mercury lamp (UV irradiance 70 mW / cm²). 2 (Manufactured by Nitto Seiki Co., Ltd., product name "UM-810") UV irradiation for approximately 10 seconds (cumulative light intensity 460 mJ / cm²) 2 Next, the adhesive tape was peeled off the silicon mirror wafer, and the number of particles on the silicon wafer surface was measured under the following conditions. <Measurement conditions> Measurement equipment: Surfscan SPSP1 wafer inspection system (manufactured by KLA Tencor) Light source: Argon ion laser (wavelength 488nm) Laser irradiation angle: Normal (vertical laser irradiation) Edge cut: 55mm Measurement flow path section: The total number of particles measured in the section of 0.15 μm or more was defined as the particle count.

[0085] 6. HSP value distance Solubility parameters (HSP values) were calculated using HSPiiP version 4.1.07 calculation software. The three Hansen solubility parameters (δD, δP, and δH) of the acrylic polymers and UV-curing resins used in each example and comparative example were measured by the following method. The acrylic polymer or active energy ray-curable resin to be measured was placed in a solvent at a constant concentration in a sealable container. The solvents used were cyclohexane, toluene, chloroform, 4-methyl-2-pentanone, ethyl acetate, cyclohexanone, 1,1,2,2-tetrabromoethane, acetone, N-methyl-2-pyrrolidone, benzyl alcohol, 1-butanol, acetic acid, 2-methoxyethanol, γ-butyrolactone, N,N-dimethylformamide, ethanol, N-methylformamide, ethanolamine, formamide, and 2-propanol. The container was then hand-shook to thoroughly mix the acrylic polymer or active energy ray-curable resin with the solvent. The container was then left to stand at room temperature (23°C) for 24 hours. Afterward, the container was visually inspected. If precipitate or aggregates were present in the container, it was considered insoluble; if no precipitate or aggregates were present, it was considered soluble. This test was performed for each solvent, and from the test results obtained, a sphere (Hansen sphere) was drawn in Hansen space that included the coordinates of the solvent in which the target substance was dissolved, but did not include the coordinates of the solvent in which the target substance was not dissolved. The obtained values ​​were entered into the above calculation software, and the HSP values ​​of the acrylic polymer and UV-curing resin were calculated using the following formula. HSP = √(δD^2 + δP^2 + δH^2) The distance between HSP values ​​was calculated using the above-mentioned calculation software based on the HSP values ​​of the obtained acrylic polymer and the HSP values ​​of the active energy ray curable resin.

[0086] [Table 2]

[0087] In the examples of the present invention, the adhesive tapes contained 20% or less of components with a molecular weight of 1000 or less in the sol. In the adhesive tapes of Examples 1 to 4, the sol contained 0% of components with a molecular weight of 1000 or less. The total amount of particles on the wafer surface, which was the adherend, was reduced. [Industrial applicability]

[0088] The adhesive tape according to the embodiment of the present invention can be suitably used for semiconductor wafer processing applications. [Explanation of symbols]

[0089] 10 Adhesive layer 20 Base material 100 Adhesive Tapes

Claims

1. It comprises a base material and an adhesive layer made of an active energy ray curable adhesive, The sol component of the adhesive layer after irradiation with active energy rays contains 20% or less of a component with a weight-average molecular weight of 1000 or less. An adhesive tape in which the adhesive strength of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less.

2. The adhesive tape according to claim 1, wherein the active energy ray curable adhesive is a water-dispersible adhesive.

3. The adhesive tape according to claim 2, wherein the active energy ray curable adhesive comprises a water-dispersible acrylic polymer and an active energy ray curable resin.

4. The adhesive tape according to claim 3, wherein the active energy ray curable resin includes urethane (meth)acrylate.

5. The adhesive tape according to claim 3, wherein the HSP value distance between the water-dispersible acrylic polymer and the active energy ray-curable resin is 8 or less.

6. An adhesive tape according to any one of claims 1 to 5, used in semiconductor wafer processing.

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