Adhesive tape

Abstract

The invention relates to an adhesive tape. Provided is an adhesive tape which can be easily peeled off from the surface of an adherend after processing, and which further suppresses microparticles from remaining on the surface of the adherend. The adhesive tape according to an embodiment of the present invention is provided with a substrate and an adhesive layer containing an active energy ray-curable adhesive, the content of a component having a weight-average molecular weight of 1000 or less contained in a sol component of the adhesive layer after active energy ray irradiation is 20% or less, and the adhesive force of the adhesive layer after active energy ray irradiation 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 adhered objects. For example, in semiconductor wafer processing, they are used to properly hold the semiconductor wafer, which is the adhered object, during back-side grinding and dicing processes. In recent years, with the advancement of chip miniaturization and thinning, there is a demand for adhesive tapes that can properly maintain the adhesive strength of semiconductor wafers even when they are ground thinner during processing. Processed semiconductor wafers tend to be thin and easily broken, and may break when the adhesive tape is peeled off. Therefore, there is a need for easily peelable adhesive tapes that can be easily peeled off from the adhered object after processing. As such adhesive tapes, adhesive tapes using UV-curable adhesives have been proposed (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-31620 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, even when using such adhesive tapes, fine foreign matter may sometimes remain on the wafer surface after the tape is peeled off. This fine foreign matter can adversely affect the function of the manufactured semiconductor wafer. In recent years, with the continuous development of high-performance semiconductors, the presence of such fine foreign matter can become particularly problematic in the manufacture of high-performance semiconductors. Therefore, there is a need for adhesive tapes that can be easily peeled off from the surface of the adhered material after processing and that further suppress the residue of particles on the adhered material surface.

[0008] means for solving problems

[0009] 1. The adhesive tape of the present invention comprises a substrate and an adhesive layer comprising 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 the component with a weight average molecular weight of 1000 or less, and the adhesive force of the adhesive layer after irradiation with active energy rays is 0.04 N / 20 mm or less.

[0010] 2. In the adhesive tape described in 1 above, the active energy ray curable adhesive can be a water-dispersible adhesive.

[0011] 3. In the adhesive tape described in 1 or 2 above, the active energy ray-curable adhesive may comprise a water-dispersible acrylic polymer and an active energy ray-curable resin.

[0012] 4. In the adhesive tape described in 3 above, the active energy ray-curable resin may contain urethane (meth)acrylate.

[0013] 5. In the adhesive tape described in 3 or 4 above, the HSP value distance between the water-dispersible acrylic polymer and the active energy radiation-curable resin can be 8 or less.

[0014] 6. The adhesive tape described in any one of 1 to 5 above can be used for semiconductor wafer processing.

[0015] Invention Effects

[0016] According to embodiments of the present invention, an adhesive tape that can be easily peeled off from the surface of the adhered object after processing and further suppresses the residue of particles on the surface of the adhered object can be provided. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of an adhesive tape according to one embodiment of the present invention.

[0018] Label Explanation

[0019] 10 adhesive layers

[0020] 20 substrates

[0021] 100 adhesive tape Detailed Implementation

[0022] A. Adhesive tape

[0023] A-1. Overall Structure of Adhesive Tape

[0024] The adhesive tape according to embodiments of the present invention comprises a substrate and an adhesive layer containing an active energy radiation-curable adhesive. The adhesive layer irradiated with active energy radiation contains 20% or less of a component with a weight average molecular weight of 1000 or less (hereinafter also referred to as a low molecular weight component), and the adhesive strength of the adhesive layer after irradiation with active energy radiation is 0.04 N / 20 mm or less. Such an adhesive tape provides a material that can be easily peeled from the surface of the adhered object after processing and further suppresses particulate residue on the surface of the adhered object. It is believed that the component with a weight average molecular weight of 1000 or less in the sol component of the adhesive layer after irradiation with active energy radiation becomes fine particles and remains on the surface of the adhered object, potentially contributing to particulate contamination of the adhered object surface. If the low molecular weight component in the sol component is 20% or less, particulate contamination on the surface of the adhered object after peeling off the adhesive tape can be suppressed. Furthermore, the adhesive strength of the adhesive layer after irradiation with active energy radiation is 0.04 N / 20 mm or less. If the adhesive strength of the adhesive layer after irradiation with active energy rays is less than 0.04 N / 20 mm, it can be peeled off from the substrate more easily. As a result, it is possible to suppress the residue of fine components from the adhesive layer on the surface of the substrate during peeling.

[0025] Figure 1 This is a schematic cross-sectional view of an adhesive tape according to an embodiment of the present invention. The adhesive tape 100 sequentially comprises a substrate 20 and an adhesive layer 10. The adhesive tape 100 may also include any suitable layer. For example, an intermediate layer (not shown) may be formed between the substrate 20 and the adhesive layer 10. Including an intermediate layer improves adhesion to substrates with uneven surfaces. In one embodiment, an antistatic layer may be formed.

[0026] The sol component of the adhesive layer after irradiation with active energy rays contains 20% or less of the component with a weight average molecular weight of 1000 or less, preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. The less the component with a weight average molecular weight of 1000 or less in the sol component, the more preferred; it can also be 0%. In this specification, the proportion of the component with a weight average molecular weight of 1000 or less in the sol component of the adhesive layer after irradiation with active energy rays refers to the proportion of the component with a weight average molecular weight of 1000 or less in the soluble component when the soluble component of the adhesive tape after irradiation with active energy rays is set to 100%. Specifically, it refers to the value obtained by the following method.

[0027] <Determination of Low Molecular Weight Components in Sol>

[0028] Collect about 0.1 part by weight of a specimen (adhesive layer and substrate) from the adhesive tape after active energy ray irradiation. It should be noted that when the material used for the substrate contains components that can dissolve in ethyl acetate (such as additives like plasticizers, antistatic agents, etc.), the substrate is peeled off and only 0.1 part by weight of the adhesive layer is used. Wrap the collected specimen with a porous polytetrafluoroethylene membrane having an average pore size of 0.2 μm (such as the product name "NITOFLON (registered trademark) NTF1122" manufactured by Nitto Denko Corporation and its equivalents), and tie it with a kite string (タコ糸). Then, immerse it in 50 mL of ethyl acetate at room temperature for 7 days to dissolve the soluble components (sol components) outside the membrane. Next, collect all the soluble components into a screw tube, and let the soluble component solution in the screw tube stand at room temperature to air dry. Then, add tetrahydrofuran (THF) to the screw tube so that the solid components remaining in the screw tube become 3.3 g / L, and let it stand for 1 day to dissolve. Filter this solution with a syringe filter, and then measure the molecular weight of the soluble components (sol components) by the GPC method under the following conditions, and make a molecular weight curve. In the obtained 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.

[0029] <GPC measurement conditions>

[0030] Measurement conditions: sample introduction amount 500 mg, column temperature 40 °C, flow rate 1.0 mL / min

[0031] Apparatus: manufactured by Tosoh Corporation, product name "HLC 8320GPC"

[0032] The gel fraction of the adhesive tape after active energy ray irradiation is preferably 90% or more, more preferably 93% or more, and further preferably 95% or more. The higher the gel fraction of the adhesive tape after active energy ray irradiation, the more preferable. If the gel fraction of the adhesive tape after active energy ray irradiation is within the above range, the adhesive tape after active energy ray irradiation can be easily peeled off from the adherend. In this specification, the gel fraction of the adhesive tape refers to the value measured by the following method.

[0033] <Method for measuring gel fraction>

[0034] Cut the adhesive tape with a polyester film subjected to peeling treatment laminated on the adhesive layer into a specimen of 5 cm × 5 cm. Irradiate ultraviolet rays (UV) from the substrate side to the adhesive tape (cumulative light amount: 460 mJ / cm 2(Converted to 365nm) Then, the polyester film that had undergone the peeling treatment was peeled off from the sample. Next, approximately 0.1 parts by weight of the sample was cut from the UV-irradiated sample. Then, the cut sample was wrapped in a pouch using a porous polytetrafluoroethylene membrane (manufactured by Nitto Denko Corporation, trade name "NITOFLON (registered trademark) NTF1122", porosity 75%, thickness 85μm) with an average pore size of 0.2μm (previously measured weight) and kite string (Wg1), and the total weight was measured (Wg2). In addition, the weight of the adhesive tape substrate was calculated based on the area and the specific gravity of the substrate material (Wg3). The package was immersed in 50mL of ethyl acetate and kept at room temperature (approximately 23°C) for 7 days to allow only the sol component in the adhesive layer to dissolve to the outside of the membrane. 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 was measured (Wg4). Substitute the measured Wg1 to Wg4 into the following formula and calculate the gel fraction of the adhesive layer.

[0035] Gel fraction (%) = [(Wg4 - Wg1 - Wg3) / (Wg2 - Wg1 - Wg3)]

[0036] When the substrate contains components soluble in ethyl acetate (such as plasticizers, antistatic agents, and other additives), the gel fraction can be calculated using the following method.

[0037] A 5cm x 5cm sample was prepared by cutting an adhesive tape with a peel-off polyester film bonded to the adhesive layer. The adhesive tape was then irradiated with ultraviolet (UV) light from the substrate side (cumulative light intensity: 460 mJ / cm²). 2 (Converted to 365nm) Then, the polyester film that had undergone the peeling treatment was peeled off from the sample. Next, about 0.1 parts by weight of the adhesive layer was collected from the sample after UV irradiation. Then, a porous polytetrafluoroethylene membrane (manufactured by Nitto Denko Co., Ltd., trade name "NITOFLON (registered trademark) NTF1122", porosity 75%, thickness 85μm) with an average pore size of 0.2μm and a kite string (Wg) was used. A The adhesive layer, after being peeled off from the substrate, was wrapped into a purse-shaped package, and the total weight (Wg) was measured. B The package was immersed in 50 mL of ethyl acetate and kept at room temperature (approximately 23°C) for 7 days to allow only the sol component in the adhesive layer to dissolve to the outside of the membrane. 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 its weight (Wg) was measured. c The measured Wg A ~Wg C Substitute into the following formula and calculate the gel fraction of the adhesive layer.

[0038] Gel fraction (%) = [(Wg) c -Wg A ) / (Wg B -Wg A )]

[0039] The adhesive strength of the adhesive tape after irradiation with active energy rays 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 strength after irradiation with active energy rays (e.g., ultraviolet light) is within the above range, an adhesive tape with light peelability can be obtained. Lower adhesive strength after irradiation with active energy rays (e.g., ultraviolet light) is preferred. In this specification, the adhesive strength of the adhesive tape after irradiation with active energy rays refers to the adhesive strength measured using the following method: The adhesive tape is cleaned in the order of toluene, ethanol, and toluene, then bonded to a dried Si mirror wafer, and stored at room temperature for 30 minutes. Next, it is irradiated with UV light (cumulative light intensity 460 mJ / cm²) using a high-pressure mercury lamp (e.g., Nitto Seiki Co., Ltd., product name "UM-810"). 2 ), and the adhesive force was measured under the following conditions.

[0040] <Conditions for testing adhesive strength>

[0041] Pulling speed: 300mm / minute

[0042] Peeling angle: 180°

[0043] Temperature: 23℃

[0044] Humidity: 50%RH

[0045] Adhesive tape width: 20mm

[0046] Adhesive tape length: 80mm

[0047] The adhesive strength of the adhesive tape before irradiation with active energy rays is 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. If the adhesive strength before irradiation with active energy rays is within the above range, it has sufficient adhesion to the adhered object. Alternatively, 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 using the following method: The adhesive tape is cleaned in the order of toluene, ethanol, and toluene, then bonded to a dried Si mirror wafer, and stored at room temperature for 30 minutes. The adhesive strength is then measured under the following conditions.

[0048] <Conditions for testing adhesive strength>

[0049] Pulling speed: 300mm / minute

[0050] Peeling angle: 180°

[0051] Temperature: 23℃

[0052] Humidity: 50%RH

[0053] Adhesive tape width: 20mm

[0054] Adhesive tape length: 80mm

[0055] The thickness of the adhesive tape in the embodiments of the present invention can be set to any suitable thickness. The thickness of the adhesive tape is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, and even more preferably 50 μm to 200 μm.

[0056] A-2. Substrate

[0057] The substrate can be composed of any suitable resin. Specific examples of resins constituting the substrate 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, cellulose resins, fluorinated resins, polyether, polystyrene resins, polycarbonate, polyethersulfone, and polyetheretherketone. Polyolefin resins or polyester resins are preferred. These resins allow ultraviolet light to pass through, thus enabling the formation of an adhesive layer using UV-curable adhesives, thereby providing an adhesive tape with light peelability.

[0058] The substrate may further contain other components without impairing the effects of the present invention. Examples of such other components include, for instance, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, and antistatic agents. The types and amounts of these other components can be used in any appropriate quantity depending on the purpose.

[0059] The thickness of the substrate is preferably 30μm to 200μm, more preferably 40μm to 180μm, and even more preferably 45μm to 180μm.

[0060] A-3. Adhesive layer

[0061] The adhesive layer of the adhesive tape in embodiments of the present invention is formed from an active energy radiation-curable adhesive. A typical example of an active energy radiation-curable adhesive is an ultraviolet-curable adhesive. The active energy radiation-curable adhesive is preferably a water-dispersible adhesive. As a water-dispersible adhesive, an adhesive containing a water-dispersible acrylic polymer, an active energy radiation-curable resin, and a photopolymerization initiator is preferred. Using such an adhesive results in excellent adhesion and superior adhesion to the adhered object. This adhesive is an aqueous adhesive composition and possesses excellent adhesion, balancing adhesion to the adhered object with light peeling properties. Therefore, it is possible to provide an adhesive that reduces environmental impact by minimizing solvent usage and is suitable for use in semiconductor wafer processing.

[0062] The Hansen solubility parameter (HSP) value difference between the water-dispersible acrylic polymer and the active energy radiation-curable resin is preferably 8 or less, more preferably 7.5 or less, and even more preferably 7.0 or less. For example, the HSP value difference between the water-dispersible acrylic polymer and the active energy radiation-curable resin is 0 or more. If the HSP value difference between the water-dispersible acrylic polymer and the active energy radiation-curable resin is within the above range, the compatibility between the water-dispersible acrylic polymer and the active energy radiation-curable resin is good, and the proportion of low molecular weight components remaining after active energy radiation irradiation can be suppressed, resulting in an adhesive tape that can be easily peeled off. Furthermore, it can suppress the residue of fine particles on the adhered material and suppress particulate contamination of the adhered material.

[0063] The Hansen solubility parameter is represented by a vector obtained by decomposing the Hildebrand solubility parameter into three components: dispersion force (δd), permanent dipole intermolecular force (δp), and hydrogen bonding force (δh), and plotting these components in three-dimensional space. Substances with similar vectors can be judged to have high mutual solubility. That is, the degree of similarity in solubility can be judged based on 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* (CRCpress, 2007). HSP values ​​have known values ​​for various resins and solvents and can be used directly, or values ​​calculated using the computer software HSPiP (Hansen Solubility Parameters in Practice). It should be noted that HSPiP also has a database of resins and solvents.

[0064] The HSP values ​​of acrylic polymers and reactive energy radiation-cured resins, whose HSP values ​​are not publicly known, can be determined using the following method. In a sealable container, the acrylic polymer or reactive energy radiation-cured resin to be tested is added to approximately 20 solvents with different HSP values, resulting in a concentration where approximately half of the 20 solvents are dissolved and approximately half are insoluble. The container is then shaken by hand to thoroughly mix the acrylic polymer or reactive energy radiation-cured resin with the solvents. The container is then allowed to stand at room temperature (23°C) for 24 hours. The container is then visually observed. The presence of precipitates or agglomerates within the container indicates insolubility, while the absence of precipitates or agglomerates indicates solubility. This test is performed on multiple solvents, and based on the results, a sphere (Hansen sphere) is plotted in Hansen space containing the coordinates of the solvents that dissolve the target substance but excluding the coordinates of solvents that do not dissolve the target substance. The obtained values ​​are input into the aforementioned calculation software, and the HSP values ​​of the acrylic polymer and reactive energy radiation-cured resin are calculated using the following formula. It should be noted that in this specification, 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-methoxy-ethanol, γ-butyrolactone, N,N-dimethylformamide, ethanol, N-methylformamide, ethanolamine, formamide, and 2-propanol were used to calculate the HSP value.

[0065]

[0066] Next, based on the dispersion force (δd) of the obtained acrylic polymer... p ), permanent dipole intermolecular forces (δp) and hydrogen bonding forces (δh) p ) and the dispersion force (δd) of active energy X-ray cured resin r ), permanent dipole intermolecular forces (δp) r ) and hydrogen bonding force (δh r The distance (Ra) between the HSP values ​​of acrylic polymers and active energy radiation-curable resins is calculated using the following formula.

[0067]

[0068] A-3-1. Water-dispersible acrylic polymers

[0069] Water-dispersible acrylic polymers (hereinafter also referred to as acrylic polymers) can be obtained by emulsifying and polymerizing 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 the water-dispersible acrylic polymer refers to the median particle size (D50) on a volume basis as determined by laser diffraction scattering.

[0070] In one embodiment, the water-dispersible acrylic polymer is preferably a polymer with a core-shell structure (hereinafter also referred to as a core-shell polymer). If a water-dispersible acrylic polymer is used as a core-shell polymer, an adhesive that has better adhesion before irradiation by active energy rays and can balance adhesion to the adhered object and light peeling properties can be provided.

[0071] Water-dispersible acrylic polymers, which are core-shell polymers, are obtained by emulsion polymerization of any suitable monomer components in a stepwise manner. For example, they can be obtained by so-called seed polymerization, in which a monomer composition forming the core is emulsion polymerized by any suitable method, and then the monomer composition forming the shell is emulsion polymerized in the presence of the polymer particles that form the core.

[0072] The core-to-shell ratio of the water-dispersible acrylic polymer is preferably 5% by weight or more, more preferably 10% by weight or more. If the weight ratio of the core to the shell is within the above range, a water-dispersible adhesive composition with excellent adhesive strength, which can balance adhesion to the adhered object and light peeling properties can be provided.

[0073] The core-shell polymer preferably comprises a shell with a glass transition temperature (Tg) of -10°C or higher and a core with a glass transition temperature (Tg) of less than -10°C. Using such a core-shell polymer yields an adhesive tape that exhibits excellent adhesion before irradiation by active energy rays and can be peeled off without damaging the adhered materials after irradiation by active energy rays.

[0074] 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 and shell portions are within the above ranges, an adhesive tape with good adhesion before irradiation by active energy rays and good peelability after irradiation by active energy rays can be provided.

[0075] In this specification, the glass transition temperature of water-dispersible acrylic polymers refers to the theoretical value calculated using the Fox formula from the monomer units constituting the polymer and their proportions. The theoretical glass transition temperature calculated using the Fox formula can be consistent with the measured glass transition temperature obtained by methods such as differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement. It should be noted that, as described below, measured glass transition temperatures may be used when the theoretical value cannot be calculated.

[0076] The Fox formula, as shown below, is the relationship between the glass transition temperature (Tg) of an acrylic polymer and the glass transition temperature (Tgi) of the homopolymer obtained by homopolymerizing the monomers constituting the acrylic polymer.

[0077] 1 / Tg=Σ(Wi / Tgi)

[0078] (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).)

[0079] The glass transition temperature of the homopolymer used in the calculation of Tg can be any value recorded in appropriate data. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of those monomers.

[0080] 2-Ethylhexyl acrylate -70℃

[0081] Methyl methacrylate 8℃

[0082] Acrylic acid 106℃

[0083] 2-Acryloyloxyethyl succinate -40℃

[0084] 4-Hydroxybutyl acrylate -40℃

[0085] N-Acryloylmorpholine 145℃

[0086] Butyl acrylate -55℃

[0087] Ethyl acrylate -20℃

[0088] 2-Hydroxyethyl Acrylate -15℃

[0089] For the glass transition temperatures of homopolymers of monomers other than those exemplified above, values ​​can be used, for example, those described in the *Polymer Handbook* (3rd edition, John Wiley & Sons, Inc., 1989). It should be noted that, in cases where multiple values ​​are provided, the highest value is adopted.

[0090] For monomers whose glass transition temperature is not recorded in the aforementioned "Polymer Handbook," the value obtained using the method described in Japanese Patent Application 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 the polymerization solvent are added to a reactor equipped with a thermometer, stirrer, nitrogen inlet pipe, and reflux condenser, and stirred for 1 hour while purging with nitrogen. After removing oxygen from the polymerization system through this operation, the temperature is raised to 63°C and reacted for 10 hours. Then, it is cooled to room temperature to obtain a homopolymer solution with a solid content concentration of 33% by weight. Next, the homopolymer solution is cast onto a release liner and dried to prepare a test sample (sheet-shaped homopolymer) with a thickness of about 2 mm. The test sample was punched into a disc shape with a diameter of 7.9 mm, clamped with parallel plates, and viscoelasticity was measured in shear mode using a viscoelasticity testing machine (manufactured by ARES and Rheometrics). The temperature range was -70°C to 150°C, with a heating rate of 5°C / min while a shear strain of 1 Hz was applied. The peak temperature of tanδ was taken as the Tg of the homopolymer.

[0091] A-3-1-1. Monomer Components

[0092] The monomer composition used to form the core and shell can be tailored to form a core or shell with any suitable glass transition temperature. For example, monomers can be selected and emulsion polymerization can be carried out based on the Fox formula described above to form a core or shell with a designed glass transition temperature Tg.

[0093] As a monomer component, any suitable acrylic monomer can be used. As a representative monomer component, alkyl (meth)acrylates can be used. Specific examples of alkyl methacrylates include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecanyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, octadecyl methacrylate, nonadecanyl methacrylate, eicosyl methacrylate, and other C1-20 alkyl methacrylates. Alkyl methacrylates may be used alone or in combination of two or more. In this specification, (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0094] The monomer composition may also contain any other suitable monomers capable of copolymerizing with alkyl (meth)acrylates. Examples include: carboxyl-containing monomers such as acrylic acid and methacrylic acid; anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyl-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-hydroxylaurate (meth)acrylate, and methyl (4-hydroxymethylcyclohexyl)methacrylate; sulfonic acid-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; and (meth)acrylate... Monomers containing alkoxyalkyl esters of (meth)acrylate, such as methoxyethyl ester; maleimide monomers such as N-cyclohexylmaleimide and N-isopropylmaleimide; itaconimide monomers such as N-methylitconimide and N-ethylitconimide; succinimide monomers; vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, and methylvinylpyrrolidone; cyano-containing monomers such as acrylonitrile and methacrylonitrile; epoxy-containing acrylic monomers such as glycidyl methacrylate; diol acrylate monomers such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate; acrylate monomers containing heterocycles, halogen atoms, or silicon atoms such as tetrahydrofurfuryl methacrylate, fluorinated (meth)acrylate, and organosilicon (meth)acrylate; olefin monomers such as isoprene, butadiene, and isobutylene; and vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether. By including these monomeric components, it is possible to modify properties such as cohesion, heat resistance, and crosslinking. These monomeric components can be used individually or in combination of two or more.

[0095] In one embodiment, amide-containing monomers are preferably used as the monomeric component constituting the shell. Specific examples of amide-containing monomers include: (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-hydroxymethyl(meth)acrylamide, N-hydroxymethyl-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide, etc.; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam, etc. N-(meth)acryloylmorpholine, N,N-diethyl(meth)acrylamide, and N-isopropylacrylamide are preferred, with N-acryloylmorpholine being more preferred. Using an amide-containing monomer as the monomer used in the polymerization of the shell can improve the initial adhesive strength of the adhesive layer. The proportion of the amide-containing monomer in all monomers constituting the shell is, for example, 0.01% to 10% by weight, preferably 0.1% to 7% by weight.

[0096] In one embodiment, the acrylic polymer described above is preferably a polymer obtained by polymerizing a monomer composition comprising a carboxyl-containing monomer as a monomer component, as shown in formula (1). When the acrylic polymer is a core-shell polymer, the carboxyl-containing monomer shown in formula (1) may be included only in the monomer composition used in the polymerization of the core, only in the monomer composition used in the polymerization of the shell, or in both the monomer composition used in the polymerization of the core and the monomer composition used in the polymerization of the shell. Only one carboxyl-containing monomer may be used, or two or more may be used in combination.

[0097]

[0098] (In the formula, R) 1 R represents a hydrogen atom or a methyl group. 2 (This represents a divalent hydrocarbon group, x represents an integer from 1 to 20, and y represents 0 or 1.)

[0099] R 1 Represents a hydrogen atom or a methyl group. x is an integer from 1 to 20, preferably an integer from 1 to 10, and more preferably an integer from 1 to 8. y is 0 or 1. R 2This indicates 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. R is preferred. 2 It is a straight-chain or branched alkylene or cycloalkylene group, more preferably a straight-chain or branched alkylene or cycloalkylene group having 1 to 20 carbon atoms, and even more preferably a straight-chain or branched alkylene or cycloalkylene group having 1 to 10 carbon atoms. If x is within the above range, R 2 If the divalent hydrocarbon group is as described above, an adhesive with excellent dispersion stability and coatability can be obtained.

[0100] As a carboxyl-containing monomer represented by formula (1), examples include: 2-acryloyloxyethyl succinate, 2-methacryloyloxyethyl succinate, 2-acryloyloxyethyl hexahydrophthalic acid, ω-carboxyl-polycaprolactone (n≈2) monoacrylate, 2-methacryloyloxyethyl hexahydrophthalic acid, etc.

[0101] Commercially available products can be used as the carboxyl-containing monomer shown in formula (1). Examples of commercially available products include: "HOA-MS", "Light Ester HO-MS(N)", "Light Acrylat HOA-HH(N)" manufactured by Kyoei Chemicals, and "ARONIX M-5300" manufactured by Toa Synthetic Co., Ltd.

[0102] Relative to 100 parts by weight of the monomer component (in the case of core-shell polymers, the monomer component used for polymerization of the core, or the monomer component used for polymerization of the shell), the content ratio of the carboxyl-containing monomer shown in 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. If the content ratio of the carboxyl-containing monomer shown in Formula (1) is within the above range, an adhesive with excellent dispersion stability and coatability can be obtained.

[0103] A-3-2. Surfactants

[0104] Any suitable surfactant can be used as the surfactant. Reactive surfactants are preferred. Reactive surfactants not only function as surfactants but also possess free radical polymerizable functional groups in their molecules (e.g., vinyl, propenyl, allyl, allyl ether, and other free radical reactive groups). By using reactive surfactants, contamination of the adhered objects by adhesives using water-dispersible acrylic polymers can be reduced, and the adhesive strength of the adhesive composition before radiation irradiation treatment can be improved. Furthermore, the water resistance of adhesive tapes (e.g., adhesive layers) using the adhesive composition is improved, and peeling of the adhesive tape can be suppressed even when water is applied during processing.

[0105] As reactive surfactants, examples include surfactants obtained by introducing free radical polymerizable functional groups (free radical reactive groups) such as propenyl and allyl ether groups into any suitable surfactant (e.g., anionic surfactants, nonionic surfactants, etc.). Reactive surfactants possess free radical polymerizable functional groups related to olefinic unsaturated double bonds, and compared to non-reactive surfactants, they can reduce the saturated water absorption rate of the formed adhesive layer. Furthermore, reactive surfactants preferred from the viewpoints of the stability of the aqueous dispersion and the durability of the adhesive layer can be used alone or in combination of two or more.

[0106] Specific examples of anionic surfactants include: higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate; polyoxyethylene alkyl aryl ether sulfates such as sodium polyoxyethylene nonylphenyl ether sulfate; alkyl sulfosuccinates such as sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, and sodium polyoxyethylene lauryl sulfosuccinate, and their derivatives; and polyoxyethylene stilbene phenyl ether sulfates, etc. Specific examples of nonionic surfactants include: polyethylene oxide alkyl ethers such as polyethylene oxide lauryl ether and polyethylene oxide stearyl ether; polyethylene oxide alkylphenyl ethers such as polyethylene oxide octylphenyl ether and polyethylene oxide nonylphenyl ether; sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, and other sorbitan higher fatty acid esters; polyethylene oxide sorbitan monolaurate and other sorbitan higher fatty acid esters; polyethylene oxide monolaurate, polyethylene oxide monostearate, and other sorbitan higher fatty acid esters; glycerol monooleate, glycerol monostearate, and other glycerol higher fatty acid esters; polyethylene oxide-polypropylene block copolymers, polyethylene oxide stilbene phenyl ethers, etc.

[0107] Commercially available products can be used as reactive surfactants. 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 Pharmaceutical Co., Ltd.; "ADEKA REASOAP SR-10N" and "ADEKA REASOAP SR-20N" manufactured by Asahi Denka Kogyo Co., Ltd.; and "LATEMUL PD-104" manufactured by Kao Corporation; sulfosuccinate 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 Co., Ltd.; and "AQUALONH-2855A" and "AQUALON" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. "H-3855B", "AQUALON H-3855C", "AQUALON H-3856", "AQUALON HS-05", "AQUALON HS-10", "AQUALON HS-20", "AQUALON HS-30", "AQUALON BC-05", "AQUALON NBC-10", "AQUALON BC-20", and products manufactured by Asahi Denka Kogyo Co., Ltd. under the brand names "ADEKA REASOAP SDX-222", "ADEKA REASOAP SDX-223", "ADEKA REASOAP SDX-232", "ADEKA REASOAP SDX-233", "ADEKA REASOAP SDX-259", "ADEKA REASOAP SE-10N", "ADEKA REASOAP Alkyl phenyl ethers or alkyl phenyl esters such as "SE-20N"; (meth) acrylate sulfates such as "ANTOX MS-60" and "ANTOX MS-2N" manufactured by Nippon Emulsifier Co., Ltd., and "ELEMINOL RS-30" manufactured by Sanyo Chemical Co., Ltd.; and phosphate esters such as "H-3330PL" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., and "ADEKA REASOAP PP-70" manufactured by Asahi Denka Kogyo Co., Ltd.Specific examples of nonionic reactive surfactants include alkyl ether reactive surfactants such as "ADEKA REASOAP ER-10", "ADEKA REASOAP ER-20", "ADEKA REASOAP ER-30", and "ADEKA REASOAP ER-40" manufactured by Asahi Denka Kogyo Co., Ltd.; "LATEMUL PD-420", "LATEMUL PD-430", and "LATEMUL PD-450" manufactured by Kao Corporation; alkyl ether reactive surfactants such as "AQUALON RN-10", "AQUALON RN-20", "AQUALON RN-30", and "AQUALON RN-50" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.; and "ADEKA REASOAP NE-10", "ADEKA REASOAP NE-20", "ADEKA REASOAP NE-30", and "ADEKA REASOAP NE-30" manufactured by Asahi Denka Kogyo Co., Ltd. Alkyl phenyl ethers or alkyl phenyl esters such as “NE-40”; (meth) acrylate sulfates such as “RMA-564”, “RMA-568”, and “RMA-1114” manufactured by Japan Emulsifier Co., Ltd.

[0108] Anionic reactive surfactants are preferred as reactive surfactants. Anionic reactive surfactants generally exhibit excellent polymerization stability and are preferred from the viewpoint of particle stability and appearance. Alternatively, both anionic and nonionic reactive surfactants can be used in combination.

[0109] In one embodiment, the reactive surfactant SO4 2- The concentration of ions is preferably 100 μg / g or less. Furthermore, the reactive surfactant is preferably an ammonium salt type surfactant. The adhesive tape of the embodiments of the present invention can be an adhesive tape used in semiconductor wafer processing. Therefore, impurity ions contained in the adhesive may become a problem. Therefore, it is preferable that the adhesive contains few impurity ions. If SO4 2- When the concentration of ions is within the above-mentioned range, and an ammonium salt-type surfactant is used, the adverse effects caused by impurity ions can be suppressed. It should be noted that methods for reducing or removing impurity ions include, for example, ion exchange resin methods, membrane separation methods, and impurity precipitation filtration methods using alcohols, or any suitable method.

[0110] The reactive surfactant is used in any suitable amount. The reactive surfactant is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the monomer composition. If the content of the reactive surfactant is greater than 5 parts by weight relative to 100 parts by weight of the monomer composition, when the adhesive composition is used in an adhesive tape for semiconductor wafer processing, the component pieces may peel off from the adhesive tape during the dicing process or subsequent processes. Furthermore, if the content of the reactive surfactant is less than 0.1 parts by weight relative to 100 parts by weight of the monomer composition, a stable emulsion state may not be maintained.

[0111] Alternatively, reactive surfactants and surfactants without free radical polymerizable functional groups can be used in combination. Examples of surfactants without free radical polymerizable functional groups include: anionic or nonionic surfactants such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and sodium polyoxyethylene alkyl sulfosuccinate; and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene polyoxypropylene block polymers. Only one of these surfactants can be used, or two or more can be used in combination.

[0112] A-3-3. Polymerization methods for water-dispersible acrylic polymers

[0113] Water-dispersible acrylic polymers can be polymerized by any suitable method. For example, water such as ion-exchanged water, a monomer composition, a surfactant, a polymerization initiator, and any additives can be added to a reaction vessel, mixed, and subjected to emulsion polymerization to obtain a water-dispersible acrylic polymer. In the case where the water-dispersible acrylic polymer is a core-shell polymer, it can be obtained, for example, by adding a monomer composition containing monomers forming the core, water, a surfactant, a polymerization initiator, and any additives to a reaction vessel, mixing, and subjected to emulsion polymerization to form polymer particles forming the core; then, adding a monomer composition containing monomers forming the shell, water, a surfactant, a polymerization initiator, and any additives to the reaction vessel, mixing, and subjected to emulsion polymerization to form the shell, thereby obtaining a water-dispersible acrylic polymer as a core-shell polymer. Examples of arbitrary additives include chain transfer agents and silane coupling agents.

[0114] Any suitable polymerization initiator can be used as a polymerization initiator. Examples of azo polymerization initiators include: 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amynylpropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropanedisulfate), 2,2'-azobis(N,N'-dimethyleneisobutyronitrile); persulfates such as potassium persulfate and ammonium persulfate; peroxide polymerization initiators such as benzoyl peroxide, tert-butyl hydroperoxide, and hydrogen peroxide; and redox initiators formed by combinations of peroxides and reducing agents [e.g., combinations of peroxides and ascorbic acid (such as combinations of hydrogen peroxide aqueous solution and ascorbic acid), combinations of peroxides and iron(II) salts (such as combinations of hydrogen peroxide aqueous solution and iron(II) salt), and combinations of persulfates and sodium bisulfite]. Polymerization initiators can be used in single-agent or in combination of two or more.

[0115] 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 relative to 100 parts by weight of the monomer composition, preferably 0.02 parts by weight to 0.5 parts by weight.

[0116] 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 thiol, glycidyl thiol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl mercaptoacetic acid, 2,3-dimercapto-1-propanol, etc. Only one chain transfer agent can be used, or two or more can be used in combination. The content of the chain transfer agent is typically 0.001 parts by weight to 0.5 parts by weight per 100 parts by weight of the monomer composition.

[0117] Water-dispersible acrylic polymers are obtained by emulsion polymerization of any additives such as monomer compositions, reactive surfactants, polymerization initiators, and chain transfer agents. Therefore, water-dispersible acrylic polymers can be prepared in emulsion form. Any suitable method can be used as the emulsion polymerization method. Specifically, examples include emulsion polymerization methods utilizing conventional one-time addition methods (one-time polymerization methods), monomer dropwise addition methods, and monomer emulsion dropwise addition methods. When adding monomers, etc., the addition can be continuous or segmented. It should be noted that the polymerization temperature can be set to any suitable value depending on the type of polymerization initiator, etc., for example, in the range of 5°C to 100°C. Furthermore, it is preferable to further add alkaline aqueous solutions such as ammonia, various water-soluble amines, sodium hydroxide aqueous solution, and potassium hydroxide aqueous solution to the solution of the water-dispersible acrylic polymer obtained by emulsion polymerization, thereby adjusting the pH to, for example, 6 to 11, preferably 7 to 10.

[0118] The gel fraction of the water-dispersible acrylic polymer is preferably 50% by weight or more, 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 after irradiation with active energy rays is difficult to reduce, and contamination of adhered materials due to the sol components is easily generated. For example, the gel fraction of the water-dispersible acrylic polymer is 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 ratio of insoluble components to solvents such as ethyl acetate. Specifically, the gel fraction can be determined as the weight fraction (in weight %) of the insoluble components after the water-dispersible acrylic polymer has been impregnated in ethyl acetate at 23°C for 7 days relative to the sample before impregnation.

[0119] A-3-4. Resin Cured by Active Energy Rays

[0120] As an active energy ray-curable resin, any suitable resin capable of curing with active energy rays such as ultraviolet light can be used. Specifically, an active energy ray-curable resin with an HSP value difference of 8 or less from that of the acrylic polymer used in the adhesive is preferred. As an active energy ray-curable resin, an ultraviolet-curable resin is preferred. As an ultraviolet-curable resin, for example, ultraviolet-curable monomers and / or oligomers can be used. Examples of ultraviolet-curable monomers include: urethane (meth)acrylates, 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 can be a self-emulsifying urethane (meth)acrylate. Examples of UV-curable oligomers include: urethane oligomers, polyether oligomers, polyester oligomers, polycarbonate oligomers, and polybutadiene oligomers. Oligomers with a molecular weight of approximately 100 to approximately 30,000 are preferred. Only one monomer or oligomer can be used, or two or more can be used in combination. It should be noted that the active energy radiation-curable resin can be emulsified using any suitable surfactant or self-emulsifying urethane (meth)acrylate as needed. Emulsification facilitates the preparation of water-dispersible adhesives.

[0121] The active energy radiation-curable resin is preferably urethane (meth)acrylate. Uramel (meth)acrylate exhibits good compatibility with (meth)acrylate polymers, which can be used as base polymers for adhesives, and tends to have a low glass transition temperature. Using urethane (meth)acrylate further improves the adhesive strength before active energy radiation irradiation. Resins obtained by emulsifying polyfunctional monomers with urethane (meth)acrylate are known as active energy radiation-curable resins. In embodiments of the present invention, a higher proportion of urethane (meth)acrylate relative to the total amount of active energy radiation-curable resin is preferred. The proportion of urethane (meth)acrylate relative to the total amount of active energy radiation-curable resin is preferably 80% by weight or more, more preferably 85% by weight or more, further preferably 90% by weight or more, more preferably 95% by weight or more, and particularly preferably 98% by weight or more. In one embodiment, the proportion of urethane (meth)acrylate relative to the total amount of active energy radiation-curable resin may be 100% by weight. Multifunctional monomers are low molecular weight components. In cases where there are many multifunctional monomers, they may not be conducive to curing by active energy rays (such as ultraviolet light) and may remain as residual monomers. Residual multifunctional monomers can easily transfer to the adhered substrate and may become a cause of substrate contamination. Uraffinate (meth)acrylates, on the other hand, have a high molecular weight and can inhibit transfer to the adhered substrate even when they remain in a state where they cannot contribute to curing by active energy rays.

[0122] Commercially available products can be used as active energy ray curable resins. Examples include: Mitsubishi Chemical Corporation's "Utsubishi UT-7119" (registered trademark), Daiichi Kogyo Pharmaceutical Co., Ltd.'s "WUA-2," and UBE Corporation's "ETERNACOLL UW-9102." Alternatively, Mitsubishi Chemical Corporation's "Utsubishi UT-7119" can also be used as a commercially available product containing both an active energy ray curable resin and a photopolymerization initiator. These active energy ray curable resins can also be selected if their HSP value difference with the acrylic polymer used in the adhesive is 8 or less.

[0123] The active energy ray-curable resin can be used in any appropriate amount, depending on the type of water-dispersible acrylic polymer. 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, relative to 100 parts by weight of the water-dispersible acrylic polymer.

[0124] A-3-5. Photopolymerization initiator

[0125] Any suitable initiator can be used as a photopolymerization initiator. Examples of photopolymerization initiators include: ethyl 2,4,6-trimethylbenzoylphenylphosphine oxide, (2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and other acylphosphine oxide photopolymerization initiators; α-keto alcohols such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl) ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxyphenylacetone, 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-one; and benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisole methyl ether. Ketals such as benzoyldimethyl ketal; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)oxime; benzophenones such as benzoylbenzoic acid and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthones such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphonates; α-hydroxyacetophenones such as 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1-one. Photopolymerization initiators can be used alone or in combination of two or more. From the viewpoint of being soluble (compatible) with water-dispersible acrylic polymer solutions, it is preferable to use photopolymerization initiators that are liquid at room temperature (e.g., 23°C).

[0126] Commercially available products can be used as photopolymerization initiators. For example, products manufactured by IGM Resins under the following trade names: Omnirad 127D, Omnirad TPO-L, Omnirad TPO, Omnirad 651, Omnirad 184, Omnirad 500, etc.

[0127] The photopolymerization initiator can be used in any suitable amount. The content of the photopolymerization initiator is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, relative to 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, it may not cure sufficiently upon irradiation with active energy rays. If the content of the photopolymerization initiator is greater than 20 parts by weight, the storage stability of the water-dispersible adhesive composition may decrease.

[0128] A-3-6. Crosslinking agent

[0129] In one embodiment, the adhesive composition may further comprise 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 difunctional or higher epoxy crosslinking agents, isocyanate crosslinking agents, carbodiimide crosslinking agents, α-azoline crosslinking agents, aziridine crosslinking agents, melamine resin crosslinking agents, metal chelate crosslinking agents, peroxide crosslinking agents, and hydrazine crosslinking agents. Only one crosslinking agent may be used, or two or more may be used in combination.

[0130] Specifically, examples of crosslinking agents include: epoxy crosslinking agents such as N,N,N',N'-tetraglycidyl m-phenylenediamine, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane, and 1,6-hexanediol diglycidyl ether; isocyanate crosslinking agents such as toluene diisocyanate (blocked type); carbodiimide crosslinking agents such as "CARBODILITE V-01 (manufactured by Nisseibo Co., Ltd.)"; epoxy crosslinking agents such as polyethylene glycol diglycidyl ether and polyglycerol polyglycidyl ether; water-dispersible isocyanate crosslinking agents such as "ELASTRON BN-69 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.)"; α-azoline crosslinking agents such as "EPOCROS WS-500 (manufactured by Nippon Shokubai Co., Ltd.)"; and products such as "Chemitite". Aziridine crosslinking agents such as "PZ-33 (manufactured by Nippon Shokubai Co., Ltd.)"; hydrophilic carbodiimide crosslinking agents such as "CARBODILITE V-02 (manufactured by Nisshinbo Co., Ltd.)" and "CARBODILITE V-04 (manufactured by Nisshinbo Co., Ltd.)"; crosslinking agents containing active hydroxymethyl groups such as hexamethylolmelamine and active alkoxymethyl groups such as hexamethoxymethylmelamine; metal chelate crosslinking agents such as "Orgatix AI135 (manufactured by Matsumoto Pharmaceutical Co., Ltd.)"; and hydrazine crosslinking agents such as adipic acid dihydrazide and phthalic acid dihydrazide.

[0131] 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, relative to 100 parts by weight of the acrylic polymer. As described above, the water-dispersible adhesive composition may be free of crosslinking agent (i.e., the crosslinking agent content may be 0 parts by weight).

[0132] A-3-7. Additives

[0133] Adhesives may contain any suitable additives as needed. Examples of additives include: catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, anti-aging agents, conductive materials, UV absorbers, light stabilizers, peel modifiers, softeners, flame retardants, solvents, etc. Additives may be used in any suitable amount depending on the purpose.

[0134] The thickness of the adhesive layer can be set to any suitable 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, sufficient adhesive force can be achieved to the adhered objects.

[0135] B. Method for manufacturing adhesive tape

[0136] The adhesive tape according to embodiments of the present invention can be manufactured by any suitable method. For example, it can be obtained by coating an adhesive onto a release liner and allowing it to dry to form an adhesive layer on the release liner, and then transferring the adhesive layer onto a substrate. Alternatively, the adhesive tape can be obtained by coating an adhesive onto a substrate and allowing it to dry. Various methods can be used as adhesive coating methods, such as doctor blade coating, air knife coating, gravure coating, gravure reverse coating, reverse roller coating, lip die coating, die-cut coating, dip coating, offset printing, flexographic printing, and screen printing. Any suitable method can be used as the drying method.

[0137] C. Uses of adhesive tape

[0138] The adhesive tape of the embodiments of the present invention is suitable for use in semiconductor wafer manufacturing processes. For example, it can be used as a dicing tape and a back-grinding tape. As described above, the adhesive tape of the embodiments of the present invention properly holds the adhered material before irradiation with active energy rays, and even if the adhered material is a fine and / or thin layer after irradiation with active energy rays, the adhesive tape can be peeled off without damaging the adhered material. Therefore, it can also be applied to the processing of thinner and more complex semiconductor wafers.

[0139] Example

[0140] The present invention will now be specifically described through embodiments, but the present invention is not limited to these embodiments. Furthermore, in the embodiments, unless otherwise specified, "parts" and "%" are based on weight.

[0141] [Synthesis Example 1] Synthesis of Acrylic Polymer A

[0142] In a reaction vessel equipped with a condenser, nitrogen inlet pipe, 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-containing monomer (HOA-MS) (2-acryloyloxyethyl succinate, 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 "4-HBA"), and 5 parts by weight of reactive surfactant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name "Aqualon KH-1025") were mixed and emulsified using a homogenizer. Then, the mixture was purged with nitrogen for 1 hour while stirring. The internal bath temperature during polymerization was then controlled at 60°C. The core was created by adding 0.02 parts by weight of a water-soluble azo initiator (manufactured by Fujifilm and Koimitsu Chemical Co., Ltd., trade name "VA-057") to initiate polymerization and heating for 2 hours.

[0143] 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 acrylamide (ACMO), and 0.71 parts by weight of a reactive surfactant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name "Aqualon KH-1025") were mixed and stirred with a homogenizer to prepare a shell monomer emulsion. 0.10 parts by weight of a water-soluble azo initiator (manufactured by Fujifilm and Kogyo Pure Chemical Industries Co., Ltd., trade name "VA-057") was added to the aqueous dispersion containing the core particles. After a 10-minute induction period, the emulsified shell monomer emulsion solution was added over 2 hours, followed by a 2-hour curing reaction to prepare a core-shell type aqueous dispersion of acrylic polymer A.

[0144] [Synthesis Examples 2 and 3] Synthesis of acrylic polymers B and C

[0145] Except for changing the monomer composition of the core and shell as described in Table 1, the same procedure as in Synthesis Example 1 was followed to obtain core-shell water-dispersible acrylic polymers B and C.

[0146] [Synthetic Example 4] Synthesis of Acrylic Polymer D

[0147] 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 Nippon Oil Company, trade name "NYPER BW") were mixed to obtain a monomer composition. The obtained monomer composition was placed in a polymerization apparatus consisting of a 1L round-bottom removable flask equipped with a removable cap, separatory funnel, thermometer, nitrogen inlet tube, Liebig condenser, vacuum seal, stir bar, and stirrer blades. Nitrogen purging was performed at room temperature for 1 hour while stirring. Then, polymerization was carried out under nitrogen inflow conditions, with stirring, at 65°C for 4 hours, followed by 75°C for 2 hours, to obtain a resin solution (prepolymer).

[0148] Next, the obtained resin solution was cooled to room temperature. Then, 42.6 parts by weight of ethyl 2-isocyanate methacrylate (manufactured by Showa Denko Co., Ltd., trade name "Karenz MOI") was added to the resin solution as a compound with polymerizable carbon-carbon double bonds. Then, 0.22 parts by weight of dibutyltin dilaurate (IV) (manufactured by Wako Pure Chemical Industries Co., Ltd.) were added, and the mixture was stirred at 50°C in air for 24 hours. Ethyl acetate was then added to obtain acrylic polymer D (30% solids).

[0149]

[0150] [Example 1]

[0151] 100 parts by weight of water-dispersible acrylic polymer A, 140 parts by weight of UV-curable resin (manufactured by Mitsubishi Chemical Corporation, trade name "Ziguang (registered trademark) UT-7119"), and 3 parts by weight of photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad TPO-L") were added and mixed, and then neutralized with 10% ammonia water to obtain a water-dispersible adhesive composition.

[0152] The obtained water-dispersible adhesive composition was applied to the polysiloxane-released surface of a 38 μm thick polyester film that had undergone polysiloxane release treatment, with a dried thickness of 10 μm. The film was then dried at 125°C for 3 minutes to form an adhesive layer. Next, a substrate (manufactured by Mitsubishi Chemical Corporation, trade name "T912E50" – an easy-to-adhere polyethylene terephthalate (PET) film with a thickness of 50 μm)) was bonded to the adhesive surface of the adhesive layer to transfer the adhesive layer, thereby producing an adhesive tape.

[0153] [Examples 2-4]

[0154] Except for changing the composition of the adhesive composition as described in Table 2, the adhesive tape was obtained by operating in the same manner as in Example 1.

[0155] (Comparative Examples 1 to 3)

[0156] Except for changing the composition of the adhesive composition as described in Table 2, the adhesive tape was obtained by operating in the same manner as in Example 1.

[0157] (Comparative Example 4)

[0158] A binder composition was obtained by mixing 100 parts by weight of the solid component of acrylic polymer D, 3 parts by weight of crosslinking agent (manufactured by Mitsui Chemicals Co., Ltd., trade name "TAKENATE D101-A"), 0.2 parts by weight of photopolymerization initiator (manufactured by IGM Resins Co., Ltd., trade name "Omnirad 127D"), 1.6 parts by weight of additive 1 (manufactured by Nippon Oil Co., Ltd., trade name "MODIPER (registered trademark) AS100"), and 0.2 parts by weight of additive 2 (manufactured by Nippon Oil Co., Ltd., trade name "UNIOLD-1200").

[0159] The adhesive tape was obtained by using the obtained adhesive composition instead of the aqueous adhesive composition, except that the procedure was the same as in Example 1.

[0160] <Evaluation>

[0161] The following evaluations were conducted 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.

[0162] 1. Glass transition temperature

[0163] The glass transition temperatures of the water-dispersible acrylic polymers obtained in Synthetic Examples 1 to 3 were calculated using the following Fox formula.

[0164] 1 / Tg=Σ(Wi / Tgi)

[0165] (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).)

[0166] It should be noted that the glass transition temperature of the homopolymer of the monomer is given by the following values.

[0167] 2-Ethylhexyl acrylate -70℃

[0168] Methyl methacrylate 8℃

[0169] 2-Acryloyloxyethyl succinate -40℃

[0170] 4-Hydroxybutyl acrylate -40℃

[0171] N-Acryloylmorpholine 145℃

[0172] Butyl acrylate -55℃

[0173] Ethyl acrylate -20℃

[0174] 2-Hydroxyethyl Acrylate -15℃

[0175] 2. Gel fraction

[0176] The adhesive tape obtained in the examples or comparative examples was cut into 5cm × 5cm pieces to prepare samples. The adhesive tape was irradiated with ultraviolet (UV) light from the substrate side (cumulative light intensity: 460mJ / cm²). 2 (Converted to 365nm) Then, the polyester film that had undergone the peeling treatment was peeled off from the sample. Next, approximately 0.1 parts by weight of the sample was cut from the UV-irradiated sample. Then, the cut sample was wrapped into a pouch shape using a porous polytetrafluoroethylene membrane (manufactured by Nitto Denko Corporation, trade name "NITOFLON (registered trademark) NTF1122", porosity 75%, thickness 85μm) with an average pore size of 0.2μm (previously measured weight) and kite string (Wg1), and the total weight was measured (Wg2). In addition, the weight of the adhesive tape substrate was calculated based on the area and the specific gravity of the substrate material (Wg3). The package was immersed in 50mL of ethyl acetate and kept at room temperature (approximately 23°C) for 7 days to allow only the sol component in the adhesive layer to dissolve to the outside of the membrane. Then, the package was removed from the ethyl acetate and the ethyl acetate adhering to the outer surface was wiped off. Then, the package was dried at 130°C for 2 hours and the weight of the package was measured (Wg4). Substitute the measured Wg1 to Wg4 into the following formula and calculate the gel fraction of the adhesive layer.

[0177] Gel fraction (%) = [(Wg4 - Wg1 - Wg3) / (Wg2 - Wg1 - Wg3)]

[0178] 3. Determination of molecular weight of sol components

[0179] All soluble components collected during gel fraction determination were transferred to a spiral tube. The soluble solution in the spiral tube was then allowed to air dry at room temperature. Tetrahydrofuran (THF) was then added to bring the remaining solids in the spiral tube to 3.3 g / L, and the solution was allowed to stand for one day to dissolve. The solution was filtered using a syringe filter, and the molecular weight of the soluble components (sol components) was determined using GPC under the following conditions, resulting in a molecular weight curve. The area ratios with a weight-average molecular weight (Mw) below 1000 were calculated from the obtained molecular weight curve.

[0180] Determination conditions: Sample introduction amount 500 mg, column temperature 40℃, flow rate 1.0 mL / min

[0181] Device: Manufactured by Tosoh Corporation, product name "HLC 8320GPC"

[0182] Column: TSK gel GMHHR-H(S)

[0183] 4. Adhesive strength

[0184] The Si mirror-finished wafer (manufactured by Shin-Etsu Chemical) was pretreated by cleaning and drying in the order of toluene, ethanol, and toluene. Next, the adhesive layer of the adhesive tape from each example or comparative example was adhered to the wafer and stored at room temperature for 30 minutes. Then, the adhesion strength (adhesion strength before UV) was measured under the following conditions: Adhesive tape was similarly adhered to the wafer, and a high-pressure mercury lamp (UV irradiance 70 mW / cm²) was used. 2 The adhesive tape (manufactured by Nitto Seiki Co., Ltd., product name: UM-810) was subjected to UV irradiation for approximately 10 seconds from the substrate side (cumulative light intensity 460 mJ / cm²). 2 Next, the adhesive strength (post-UV adhesive strength) was measured under the following conditions.

[0185] <Conditions for testing adhesive strength>

[0186] Pulling speed: 300mm / minute

[0187] Peeling angle: 180°

[0188] Temperature: 23℃

[0189] Humidity: 50%RH

[0190] Adhesive tape width: 20mm

[0191] Adhesive tape length: 80mm

[0192] 5. Particle size determination

[0193] In a clean bench, the polyester film that had undergone peeling treatment was peeled off from the adhesive tape obtained in the examples or comparative examples, and the adhesive layer side of the adhesive tape was pasted onto an unused silicon mirror wafer (6 inches). It was then left to stand for 30 minutes. Then, the adhesive tape was exposed to a high-pressure mercury lamp (UV irradiance 70 mW / cm²) from the substrate side. 2 The device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") was subjected to 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.

[0194] <Measurement Conditions>

[0195] Measurement equipment: Surfscan SPSP1 wafer inspection device (manufactured by KLA Tencor).

[0196] Light source: Argon ion laser (wavelength 488nm)

[0197] Laser illumination angle: Normal (vertical laser illumination)

[0198] Edge cutting: 55mm

[0199] Particle size range determination: The total number of particles measured in the range above 0.15 μm is taken as the particle count.

[0200] 6. HSP value distance

[0201] The solubility parameters (HSP values) were calculated using HSPiiP version 4.1.07 software. The three parameters (δD, δP, and δH) of the Hansen solubility parameters of the acrylic polymers and UV-curable resins used in the examples and comparative examples were determined using the following methods.

[0202] In a sealable container, the acrylic polymer or active energy-curable resin to be tested was added at a specific concentration. The solvents used included 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-methoxy-ethanol, γ-butyrolactone, N,N-dimethylformamide, ethanol, N-methylformamide, ethanolamine, formamide, and 2-propanol. The container was then shaken by hand to thoroughly mix the acrylic polymer or active energy-curable resin with the solvent. The container was then allowed to stand at room temperature (23°C) for 24 hours. The container was then visually observed. The presence of precipitates or agglomerates in the container indicated insolubility, while the absence of precipitates or agglomerates indicated solubility. The experiment was conducted on each solvent, and based on the results, a sphere (Hansen sphere) was plotted in Hansen space containing the coordinates of the solvents that dissolved the target substance but excluding the coordinates of the solvents that did not dissolve the target substance. The obtained values ​​were input into the aforementioned calculation software, and the HSP values ​​of acrylic polymers and UV-curable resins were calculated using the following formula.

[0203]

[0204] The distance between the HSP values ​​was calculated using the aforementioned calculation software based on the HSP values ​​of the obtained acrylic polymers and the active energy radiation-cured resins.

[0205]

[0206] In the embodiments of the present invention, the proportion of components with a molecular weight of 1000 or less in the sol of the adhesive tape is 20% or less. In the adhesive tapes of Examples 1 to 4, the component with a molecular weight of 1000 or less in the sol is 0%. This reduces the total amount of particles on the wafer surface that is the adherend.

[0207] Industrial practicality

[0208] The adhesive tape of the present invention can be used for semiconductor wafer processing applications.

Claims

1. An adhesive tape, wherein, The adhesive tape comprises a substrate and an adhesive layer containing an active energy radiation-cured adhesive. After irradiation with active energy rays, the sol component of the adhesive layer contains less than 20% of components with a weight average molecular weight of less than 1000. The adhesive strength of the adhesive layer after irradiation with active energy rays is less than 0.04 N / 20 mm.

2. The adhesive tape according to claim 1, wherein, The active energy ray-cured 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 contains urethane (meth) acrylate.

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

6. The adhesive tape according to any one of claims 1 to 5, wherein, The adhesive tape is used for semiconductor wafer processing.

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