Adhesive tape for laser dicing

Abstract

To provide an adhesive tape for laser dicing which has good water permeability of water jet at the time of dicing, can suppress chip scattering due to a water flow, and leaves no paste residue in divided chips at the time of picking up, in laser dicing for guiding a laser beam by water jet.SOLUTION: There is provided an adhesive tape in which a base material, and an adhesive layer and a separator film are sequentially stacked on one surface of the base material, wherein the base material is a curable resin film obtained by curing an ionizing radiation-curable composition, and has a through hole in a thickness direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape for laser dicing used to fix a semiconductor wafer when dicing it with a laser guided by a water jet. [Background technology]

[0002] Conventionally, a blade cutting method has been used for dicing semiconductor wafers and semiconductor-related materials, which involves cutting with a high-speed rotating dicing blade. However, the cutting resistance of the blade during cutting causes the individual chips to scatter from the adhesive tape holding them in place, resulting in chipping, cracking, and other defects, which reduces the productivity and quality of semiconductor chips.

[0003] On the other hand, various dicing methods using laser beams are being investigated, including a laser dicing method that uses a laser beam guided by a water jet. In this method, the cutting resistance from the blade does not directly affect the wafer, as in the blade cutting method, so the occurrence of defects such as chipping and cracking of the chip can be reduced. In addition, because it is guided by a water jet, the wafer is cooled efficiently, and the thermal load can be reduced.

[0004] In laser dicing, where the laser is guided by a water jet, there is a problem that the pressure from the water flow on the adhesive surface of the adhesive tape that holds the wafer in place during dicing makes it easy for the individual chips to peel off the adhesive tape. To address this, Patent Document 1 proposes a water-permeable adhesive tape that prevents peeling due to the water flow by using a substrate with water-permeable perforations in the support substrate.

[0005] However, when using nonwoven fabrics or perforated substrates as water-permeable substrates, as in Patent Document 1, the perforations may be uneven or the perforation area may not be large enough. As a result, depending on the chip size and dicing conditions, water flow may not permeate easily, and chips may fly off.

[0006] In contrast, Patent Document 2 describes that by using a mesh substrate for a water-permeable substrate, the size of the holes and the opening area can be made relatively larger than those of nonwoven fabrics or perforated substrates, resulting in stable water permeability and further reduction of chip breakage and chip defects.

[0007] However, when using mesh substrates to dice materials that are more difficult to cut than silicon wafers, such as silicon carbide (SiC) wafers used as power semiconductors, high-power laser processing is required. This can damage or cut the fibers of the mesh substrate with the laser, resulting in chip breakage. Furthermore, since mesh substrates are woven fabrics with a mesh-like structure made of fibers, the contact area between the substrate and the adhesive layer is small. As a result, the adhesion between the substrate and the adhesive layer is insufficient, and the adhesive layer can peel off the substrate due to the water jet, sometimes causing chip breakage or chip defects. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2001-316648 [Patent Document 2] Japanese Patent Publication No. 2008-117943 [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention aims to provide an adhesive tape for laser dicing, in which a laser is guided by a water jet, that has good water permeability to the water jet during dicing, can suppress chip flying due to the water flow, and does not leave any adhesive residue on the chip when the individual chips are picked up. [Means for solving the problem]

[0010] The adhesive tape for laser dicing of the present invention is an adhesive tape used in laser dicing in which a laser is guided by a water jet, wherein the adhesive tape comprises a base material and a layer of adhesive and a separator film sequentially laminated on one surface of the base material, wherein the base material is a cured resin film obtained by curing an ionizing radiation-curable resin composition and has through holes in the thickness direction. The cured resin film is a cured product obtained by addition curing an ionizing radiation-curable resin composition containing a polyfunctional polymerizable compound having two or more carbon-carbon double bonds in its molecule and a polyfunctional thiol compound, wherein the polyfunctional polymerizable compound is a polyfunctional allyl compound and the polyfunctional thiol compound is a polyfunctional secondary thiol compound. The present invention provides an adhesive tape for laser dicing characterized by the following features.

[0011] The present invention provides adhesive tape for laser dicing. This can be obtained by a manufacturing method that includes at least the following steps (a) to (e). (a) A release layer of silicone-modified urethane resin is formed. Temporary support film release layer A step of forming a laminate by laminating an ionizing radiation-curable resin layer on top, (b) A step of pressing a mold (mold member) having regularly spaced protrusions on its surface that are greater than the thickness of the ionizing radiation-curable resin layer against the surface of the laminate that is not in contact with the temporary support film of the ionizing radiation-curable resin layer, thereby penetrating the protrusions in the thickness direction of the ionizing radiation-curable resin layer. (c) A step of curing the ionizing radiation-curable resin layer by irradiating it with ionizing radiation while the protrusion penetrates the ionizing radiation-curable resin layer, (d) A step of peeling off the mold and the temporary support film to obtain a cured resin film having through holes in the thickness direction, (e) Laminating an adhesive layer and a separator film onto the cured resin film. [Effects of the Invention]

[0012] The cured resin film, which is the base material of the adhesive tape for laser dicing of the present invention, is superior in transparency, flexibility, and adhesion compared to the conventionally used olefin-based synthetic resin film, and can be made into an adhesive tape with good adhesion between the base material and the adhesive layer and good damage resistance of the base material to laser light. Furthermore, in the cured resin film, through-holes in the thickness direction of the base material can be formed with high density and high precision by a mold (molding member). Therefore, in laser dicing where the laser is guided by a water jet, the water permeability of the water jet is good, defects such as chip flying and chip chipping during dicing can be suppressed, and it has become possible to provide an adhesive tape for laser dicing with no glue residue on the chips during pick-up after dicing.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic cross-sectional view showing an embodiment of the adhesive tape for laser dicing of the present invention. [Figure 2] It is a schematic cross-sectional view showing an embodiment of the manufacturing process of the adhesive tape for laser dicing of the present invention.

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described.

[0015] The adhesive tape for laser dicing of the present invention comprises a base material made of a cured resin film obtained by curing an ionizing radiation-curable resin composition, an adhesive layer, and a separator film, which are sequentially laminated. The base material of the cured resin film has through holes in the thickness direction. The cured resin film is obtained by laminating an ionizing radiation-curable resin composition onto a temporary support film, pressing a mold (mold member) having regularly spaced protrusions on its surface that are higher than the thickness of the ionizing radiation-curable resin layer onto the surface side of the ionizing radiation-curable resin layer, irradiating it with ionizing radiation while the protrusions of the mold penetrate the ionizing radiation-curable resin layer, curing the ionizing radiation-curable resin layer, and then peeling off the mold and temporary support film. This process yields a cured resin film with fine through holes formed at high density and with high precision. By laminating an adhesive layer and a separator film onto this cured resin film, the adhesive tape based on the cured resin film with through holes of the present invention can be obtained.

[0016] (base material) The substrate constituting the adhesive tape of the present invention is a cured resin film obtained by curing an ionizing radiation-curable resin layer. The ionizing radiation-curable resin composition used for the ionizing radiation-curable resin layer is a composition containing a polyfunctional polymerizable compound having two or more carbon-carbon double bonds in its molecule that are ionizing radiation polymerizable. In particular, an ionizing radiation-curable resin composition containing the polyfunctional polymerizable compound and a polyfunctional thiol compound that yields an addition cured product of the ene-thiol reaction is preferred. The ene-thiol reaction has high curing sensitivity and curability, and is less susceptible to oxygen inhibition in radical curing, resulting in excellent productivity. Furthermore, the addition cured product obtained by the ene-thiol reaction can be homogeneous, highly transparent, flexible, and adhesive, and also has excellent mechanical strength. Compared to synthetic resin films such as polyolefins used as substrates for conventional dicing adhesive tapes, the cured resin film made from this cured product has superior adhesion to the adhesive layer, resistance to damage from laser light, and expandability. Furthermore, because it also has excellent mechanical strength, the pore density of through holes can be increased, making it suitable as a substrate for the laser dicing adhesive tape of the present invention. The enthiol reaction is a reaction in which radicals are generated on a mercapto group due to irradiation with ionizing radiation, and these radicals add the mercapto group to a carbon-carbon double bond.

[0017] Examples of polyfunctional polymerizable compounds include polyfunctional (meth)acrylate compounds, polyfunctional allyl compounds, and polyfunctional vinyl compounds. Examples of polyfunctional (meth)acrylate compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, and ethylene oxide-added ditrimethylolpropane tetra(meth)acrylate. Examples include polyfunctional (meth)acrylates such as tri(acryloyloxyethyl) isocyanurate, tri(methacryloyloxyethyl) isocyanurate, alkylene oxide-added tri(acryloyloxyethyl) isocyanurate, alkylene oxide-added tri(methacryloyloxyethyl) isocyanurate, and polyfunctional (meth)acryloyl group-containing isocyanurate; and polyfunctional urethane (meth)acrylates obtained by the reaction of polyfunctional isocyanates such as tolylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate with hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

[0018] Examples of polyfunctional allyl compounds include polyfunctional allyl ethers such as ethylene glycol diallyl ether, diethylene glycol diallyl ether, propylene glycol diallyl ether, butylene glycol diallyl ether, hexanediol diallyl ether, trimethylolpropane trialyl ether, pentaerythritol tetraallyl ether, dipentaerythritol pentaallyl ether, dipentaerythritol hexaallyl ether, ethylene oxide-added trimethylolpropane trialyl ether, and ethylene oxide-added ditrimethylolpropane tetraallyl ether; polyfunctional allyl esters such as diallyl oxalate, diallyl malonate, diallyl succinate, diallyl glutarate, diallyl adipate, diallyl phthalate, triallyl trimesinate, triallyl trimellitate, and tetraallyl pyromellitate; and polyfunctional allyl group-containing isocyanurates such as triallyl isocyanurate.

[0019] Examples of polyfunctional vinyl compounds include polyfunctional vinyl ethers such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, trimethylolpropane trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexanyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, and ethylene oxide-added ditrimethylolpropane tetravinyl ether; and polyfunctional vinyl esters such as divinyl oxalate, divinyl malonate, divinyl succinate, divinyl glutarate, divinyl adipate, divinyl phthalate, trivinyl trimesinate, trivinyl trimellitate, and tetravinyl pyromellitate.

[0020] These polyfunctional polymerizable compounds can be used individually or in combination of two or more to obtain ionizing radiation-curable resin compositions. Among the polyfunctional polymerizable compounds, polyfunctional urethane (meth)acrylates are preferred to produce flexible cured resin films. Furthermore, in the case of addition cured products from the en-thiol reaction, polyfunctional allyl compounds are preferred because they tend to produce homogeneous cured products. Among the polyfunctional allyl compounds, triallyl isocyanurate is more preferred from the viewpoint of improving mechanical properties.

[0021] The polyfunctional thiol compounds used as cured products in the ene-thiol reaction are compounds having two or more mercapto groups (SH groups) in their molecule, such as trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, pentaerythritol tetrakis(3-mercaptopropionate), and tetraethylene glycol bis(3-mercaptopropionate). Examples include propyl From the viewpoint of improving properties such as adhesion and flexibility of the cured product obtained by the en-thiol reaction, it is more preferable to use polyfunctional secondary thiol compounds such as pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinan-2,4,6-trione, and trimethylolpropanetris(3-mercaptobutyrate).

[0022] When forming a cured product of the ene-thiol reaction, the proportions of the polyfunctional polymerizable compound and the polyfunctional thiol compound in the ionizing radiation-curable resin composition are preferably such that the molar ratio of the carbon-carbon double bond group of the polyfunctional polymerizable compound to the mercapto group of the polyfunctional thiol compound is in the range of 40:60 to 60:40, and more preferably in the range of 45:55 to 55:45, in order to ensure that the cured resin film has homogeneous properties.

[0023] Ionizing radiation-curable resin compositions are typically liquid resin compositions that exhibit good conformability to the protrusion shape of a mold when forming through holes in a mold. The viscosity of the ionizing radiation-curable resin composition is preferably in the range of 10 to 5,000 mPa·s, and more preferably in the range of 50 to 1,000 mPa·s.

[0024] In ionizing radiation-curable resin compositions, it is preferable to incorporate polymerization initiators to efficiently advance the curing reaction. As polymerization initiators, it is preferable to use ionizing radiation polymerization initiators. When ultraviolet light is used as the ionizing radiation, it is preferable to use photopolymerization initiators such as benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, and 2-benzothiazole-N,N-diethyldithiocarbamate.

[0025] The content of polymerization initiator in the ionizing radiation-curable resin composition is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.

[0026] The ionizing radiation-curable resin composition may contain, to the extent that the effects of the present invention are obtained, various additives such as monofunctional (meth)acrylate compounds, vinyl compounds, allyl compounds, and other radical polymerizable compounds, as well as antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, defoamers, and viscosity modifiers, as appropriate.

[0027] The thickness of the ionizing radiation-curable resin layer is preferably in the range of 50 to 300 μm, more preferably in the range of 60 to 200 μm, and even more preferably in the range of 70 to 150 μm, from the viewpoint of through-hole formation, handling of the cured resin film, and breakage and damage resistance when using adhesive tape for dicing.

[0028] As a method for forming an ionizing radiation-curable resin layer, the ionizing radiation-curable resin composition is applied uniformly to the release layer of a temporary support film to a predetermined thickness, either as is or as a coating liquid with its viscosity adjusted by a solvent, and the solvent is dried to form the ionizing radiation-curable resin layer.

[0029] Coating methods for ionizing radiation-curable resin layers include, for example, gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0030] A cured resin film is obtained by irradiating an ionizing radiation-curable resin layer with ionizing radiation to cure the ionizing radiation-curable resin composition. While ultraviolet light is typically used as the ionizing radiation, visible light, electron beams, X-rays, ion beams, etc., may also be used. Suitable ultraviolet light sources include, for example, ultra-high pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arc lamps, black lights, and metal halide lamps.

[0031] The cured resin film used as the base material for the adhesive tape of the present invention has through-holes in the thickness direction. The shape of these holes can be any shape that allows water to escape, such as circular, square, triangular, or rhombus shapes, but circular holes are preferred because they are easy to drill. The arrangement of the holes is preferably a regular arrangement of fine holes (for example, a grid such as a square grid or a triangular grid) to stabilize water permeability. The size of the holes is 0.0004 mm. 2 ~0.1mm 2 Preferably, 0.001 mm 2 ~0.05mm 2 , more preferably 0.0013 mm 2 ~0.03mm 2 The following is even more preferable. If the holes are circular, their diameter is preferably 0.022 mm to 0.35 mm, more preferably 0.035 mm to 0.25 mm, and even more preferably 0.040 mm to 0.20 mm. If the holes are square, triangular, or rhombus-shaped, the length of one side is preferably 0.01 mm to 0.30 mm, more preferably 0.03 mm to 0.20 mm, and even more preferably 0.04 mm to 0.18 mm. Furthermore, the number of holes per unit area (pore density) is 1,000,000 / m². 2 Preferably exceeding 5,000,000 pieces / m 2 The above is preferable.

[0032] The porosity of the cured resin film used as the base material is preferably 3% to 90%, more preferably 8% to 80%, even more preferably 10% to 55%, and most preferably 15% to 50%. This ensures good water permeability and prevents the chip from peeling off the adhesive tape. It also ensures the mechanical strength of the tape and the adhesion between the base material and the adhesive layer. In this case, the porosity can be calculated from the pore size and pore density using the following formula: Porosity (%) = (Pore size) × (Pore density) × 100

[0033] In this embodiment, as a method for perforating through holes in a cured resin film, a mold (mold member) having protrusions for forming holes of the aforementioned shape and size is pressed against an ionizing radiation-curable resin layer formed on a temporary support film before curing. Ionizing radiation is then irradiated with the mold's protrusions penetrating the ionizing radiation-curable resin layer to cure the ionizing radiation-curable resin layer, and after the mold and temporary support film are removed, through holes can be formed in the cured resin film. Using this method, fine through holes can be formed with higher density and precision than conventionally known perforation methods, and the water permeability of the water jet can be improved.

[0034] The material of the mold used in the above drilling method is not particularly limited, but examples include resin materials, glass materials, and other inorganic materials. Examples of resin materials include acrylic resins, styrene resins, epoxy resins, polyester resins, olefin resins, polycarbonate resins, and fluororesins. Examples of glass materials include quartz glass, high silica glass, borosilicate glass, aminosilicate glass, alkali-free glass, lead glass, barium glass, phosphate silicate glass, fluoride glass, lanthanum glass, clear crystallized glass, heat-absorbing glass, and spin-on glass. Examples of other inorganic materials include silicon, silicon carbide, sapphire, gallium nitride, and carbon.

[0035] The surface of the mold that is pressed against the ionizing radiation-curable resin layer has regularly spaced fine protrusions for perforating the cured resin film. The shape, size, and arrangement of these protrusions are the same as the shape, size, and arrangement of the holes in the cured resin film to be perforated. Furthermore, the height of the protrusions is 5 to 40 μm higher than the thickness of the ionizing radiation-curable resin layer to be perforated, more preferably 10 to 30 μm higher, and even more preferably 10 to 20 μm higher, in order to reliably form through holes. As for the method of forming the protrusions, a mold manufacturing method used in UV imprinting, which is a known technology in the semiconductor field for forming fine irregularities on a surface, can be suitably used. Examples include photolithography, electron beam lithography, interference exposure, and direct writing using a semiconductor laser.

[0036] It is preferable to apply a release treatment to the surface of the mold having protrusions in order to improve the release properties from the cured resin film formed by the curing of the ionizing radiation-curable resin layer. As for the release treatment, silicone-based release agents and fluorine-based release agents are preferred, and fluorine-based release agents having a perfluoroalkyl group are particularly preferred. Furthermore, in order to suppress detachment from the mold surface, it is preferable that the release agent has functional groups (e.g., hydroxyl groups, carboxyl groups, etc.) that can chemically bond with the surface functional groups (e.g., hydroxyl groups, carboxyl groups, etc.) of the mold material.

[0037] Conventional perforation methods can be used to create through-holes in a cured resin film, such as punching with a press or rotary roll, laser treatment, or water jet treatment. Additional perforations may be made in a cured resin film that has already been perforated using a mold, or an unperforated cured resin film can be prepared without using a mold and then perforated using conventional methods.

[0038] (Adhesive layer) As the adhesive composition used in the adhesive layer of the laser dicing adhesive tape of the present invention, commonly used acrylic adhesives, ionizing radiation-curable adhesives, heat-expandable adhesives, etc., can be used as appropriate. Ionizing radiation-curable adhesives generally contain an acrylic adhesive and an ionizing radiation polymerizable compound, and their adhesive strength decreases upon irradiation with ionizing radiation. Heat-expandable adhesives generally contain an acrylic adhesive and a foaming agent (thermal expansion agent), and their adhesive strength decreases upon heating. These types of adhesives that decrease in adhesive strength can be suitably used because they facilitate the removal of chips after dicing.

[0039] Acrylic adhesives consist of (meth)acrylic copolymers and curing agents as essential components. (Meth)acrylic copolymers can be obtained, for example, by copolymerizing one or more alkyl (meth)acrylate esters having 4 to 18 carbon atoms in the alkyl group with one or more other copolymerizable monomers having carbon-carbon double bonds using conventional methods.

[0040] Examples of the alkyl (meth)acrylates mentioned above include n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

[0041] Examples of copolymerizable monomers having a carbon-carbon double bond include acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, cyclohexyl (meth)acrylate, styrene, α-methylstyrene, vinyl acetate, N-vinyl-2-pyrrolidone, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. Among these, monomers having functional groups that can react with the curing agent described later are used as essential components.

[0042] The weight-average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 10,000 to 1,000,000, and more preferably 20,000 to 800,000. By setting the weight-average molecular weight within this range, appropriate adhesive performance can be obtained for the adhesive layer of the present invention. Note that the weight-average molecular weight is the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0043] The curing agent is used to adjust the tackiness and cohesiveness by reacting with the functional groups of the (meth)acrylic copolymer. Examples include epoxy curing agents and isocyanate curing agents.

[0044] Examples of epoxy curing agents include epoxy compounds having two or more epoxy groups in their molecules, such as 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,3-bis(N,N-diglycidylaminomethyl)toluene, 1,3-bis(N,N-diglycidylaminomethyl)benzene, and N,N,N,N′-tetraglycidyl-m-xylenediamine.

[0045] Examples of isocyanate-based curing agents include polyisocyanates having two or more isocyanate groups in their molecules, such as 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 1,3-xylylenediisocyanate, 1,4-xylylenediisocyanate, and diphenylmethane-4,4′-diisocyanate; trimers of polyisocyanates; urethane prepolymers having isocyanate groups at their ends, obtained by reacting polyisocyanates with polyols; and polyisocyanate compounds having two or more isocyanate groups in one molecule, such as trimers of the urethane prepolymers. These curing agents may be used individually or in combination of two or more types.

[0046] The amount of curing agent added can be adjusted as appropriate according to the required adhesive strength, and is typically 0.01 to 30 parts by mass, more preferably 0.1 to 15.0 parts by mass, per 100 parts by mass of (meth)acrylic copolymer.

[0047] The ionizing radiation polymerizable compounds for the aforementioned ionizing radiation-curable adhesives are, for example, low molecular weight compounds having at least two photopolymerizable carbon-carbon double bonds within a molecule that can form a three-dimensional network upon light irradiation. Specifically, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and oligoester acrylates are widely applicable.

[0048] In addition to the acrylate compounds mentioned above, urethane acrylate oligomers can also be used. Urethane acrylate oligomers are obtained by reacting a polyol compound such as polyester or polyether type with a polyvalent isocyanate compound (e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.) to obtain a terminal isocyanate urethane prepolymer, and then reacting it with an acrylate or methacrylate having a hydroxyl group (e.g., 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.).

[0049] The mixing ratio of the acrylic adhesive to the ionizing radiation polymerizable compound in the ionizing radiation-curable adhesive is 5 to 200 parts by mass, more preferably 10 to 120 parts by mass, and even more preferably 10 to 50 parts by mass of the ionizing radiation polymerizable compound per 100 parts by mass of the acrylic adhesive. By mixing within this range, the adhesive strength is appropriately reduced, and damage to the chips during pickup and adhesive residue can be suppressed. Furthermore, instead of mixing the ionizing radiation polymerizable compound with the acrylic adhesive as described above, it is also possible to make the acrylic adhesive itself an ionizing radiation polymerizable acrylic acid ester copolymer.

[0050] Furthermore, it is preferable to incorporate an ionizing radiation polymerization initiator into ionizing radiation-curable adhesives. Examples of ionizing radiation polymerization initiators include isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michlar's ketone, chlorothioxanthone, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxymethylphenylpropane. By adding at least one of these to the adhesive layer, the polymerization reaction can be efficiently promoted.

[0051] The amount of ionizing radiation polymerization initiator added is usually 0.05 to 15 parts by mass, preferably 0.2 to 10 parts by mass, per 100 parts by mass of ionizing radiation curable adhesive.

[0052] The foaming agent for the aforementioned heat-expandable adhesive can be appropriately selected from known heat-expanding agents, but among them, microencapsulated foaming agents can be preferably used. Examples of such microencapsulated foaming agents include heat-expandable microspheres in which a substance that readily gasifies and expands upon heating, such as isobutane, propane, or pentane, is enclosed within an elastic shell.

[0053] The shells of thermally expandable microspheres are usually formed from thermoplastics, thermally meltable materials, or materials that rupture upon thermal expansion. Examples include vinylidene chloride-acrylonitrile copolymers, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone. Thermally expandable microspheres can be produced by conventionally known methods, such as coacervation and interfacial polymerization.

[0054] Commercially available products can also be used as thermally expandable microspheres. Examples of such commercially available thermal foaming agents include the (trademark) Matsumoto Microsphere F series (e.g., F-30, F-50, F80S, etc.) manufactured by Matsumoto Oil & Fat Pharmaceutical Co., Ltd.

[0055] The average particle size of thermally expandable microspheres is typically around 1 to 80 μm, preferably around 3 to 50 μm, from the standpoint of dispersibility and thin-layer formation.

[0056] Furthermore, as thermally expandable microspheres, it is preferable that they have a moderate strength that prevents them from bursting until their volume expansion ratio increases to 5 times or more, and especially to 10 times or more, in order to efficiently reduce the adhesive strength of the adhesive layer containing the adhesive agent through heat treatment.

[0057] Examples of other thermal foaming agents used in the thermally expandable adhesive include, for example, inorganic foaming agents and organic foaming agents. Examples of inorganic foaming agents include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, azides, and the like. Examples of organic foaming agents include azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenyl sulfone-3,3'-disulfonyl hydrazide, 4,4'-oxybis(benzenesulfonyl hydrazide), and allyl bis(sulfonyl hydrazide); semicarbazide compounds such as ρ-toluenesulfonyl semicarbazide and 4,4'-oxybis(benzenesulfonyl semicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; and N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide. These thermal foaming agents can be used alone or in combination of two or more. Further, the thermally expandable adhesive composition containing a thermal foaming agent may contain a foaming aid as necessary.

[0058] The blending amount of the thermal foaming agent in the thermally expandable adhesive varies depending on its type, but is usually 10 to 200 parts by mass, preferably 20 to 125 parts by mass, and more preferably about 25 to 100 parts by mass with respect to 100 parts by mass of the acrylic adhesive. By setting it to 10 parts by mass or more, an effective reduction in adhesive strength after heat treatment can be obtained, and by setting it to 200 parts by mass or less, cohesive failure of the adhesive layer can be suppressed.

[0059] In the adhesive layer of the present invention, various additives such as an antioxidant, an antistatic agent, a leveling agent, and an antifoaming agent can be blended as necessary.

[0060] The coating amount of the adhesive layer is 5 to 50 g / m in order to ensure the adhesive strength and the holding strength to the adherend. 2 more preferably 10 to 30 g / m 2 is. When the coating amount of the adhesive layer is 5 g / m2 By doing so, adhesive strength and holding power can be ensured, and chip peeling due to the water jet can be suppressed. In addition, the amount of adhesive layer coating is 50 g / m². 2 By doing the following, the penetration of the water jet's water flow can be ensured, and manufacturing costs can be reduced.

[0061] The present invention provides a method for forming an adhesive layer, which involves applying the adhesive composition as is, or as a coating liquid with its viscosity adjusted using a solvent, to a film substrate or a release-treated separator film to a predetermined thickness, and then drying the solvent to form the adhesive layer.

[0062] Examples of coating methods for the adhesive layer coating liquid of the present invention include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0063] The adhesive strength of the adhesive tape of the present invention is preferably 1 N / 25 mm or more, and more preferably 2 N / 25 mm or more, in order to suppress chip flying during dicing. Furthermore, when using an ionizing radiation-curing adhesive or a thermal expansion adhesive, the decrease in adhesive strength after ionizing radiation irradiation or heating is preferably less than 1 N / 25 mm, and more preferably less than 0.5 N / 25 mm. Lower adhesive strength during pickup after dicing can reduce defects such as chipping of the chips. Note that the adhesive strength is the value obtained when measuring the peeling force against the silicon wafer mirror surface under the conditions of a measurement temperature of 23 ± 3 °C, a peeling angle of 180 °C, and a peeling speed of 300 mm / min.

[0064] (Temporary support film) The cured resin film of the present invention is obtained by coating an ionizing radiation-curable resin composition onto the release layer of a temporary support film on which a release layer has been formed, forming an ionizing radiation-curable resin layer, curing the ionizing radiation-curable resin layer by irradiating it with ionizing radiation, and then peeling off the temporary support film.

[0065] The material of the temporary support film can be, for example, a synthetic resin such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, or polyurethane, but polyethylene terephthalate film is preferred from the viewpoint of heat resistance and strength. The thickness of the temporary support film is preferably about 6 to 200 μm, and more preferably about 12 to 100 μm, from the viewpoint of handling and cost.

[0066] The release agent used in the release layer of the temporary support film can be conventionally known, such as silicone-based release agents, long-chain alkyl-based release agents, or fluorine-based release agents, or it can be a silicone-modified resin such as silicone-modified acrylic resin or silicone-modified urethane resin. Among these, it is preferable to use a silicone-based release agent, which is relatively inexpensive and provides stable release properties. Furthermore, in the process of pressing a mold against an ionizing radiation-curable resin layer laminated on the release layer of the temporary support film to penetrate the protrusions of the mold, it is more preferable to use a relatively flexible silicone-modified urethane resin as the release layer, as it allows for good adhesion between the surface of the release layer of the temporary support film and the protrusions of the mold. The better the adhesion between the surface of the release layer and the contact surface of the protrusions of the mold, the more the ionizing radiation-curable resin composition between them is extruded, ensuring the formation of through-holes.

[0067] As a silicone-based release agent, for example, a thermosetting addition-type silicone-based release agent can be suitably used. A thermosetting addition-type silicone-based release agent can be used that cures a silicone composition consisting of a polyorganosiloxane having two or more alkenyl groups in the molecule and an organohydrogenpolysiloxane as a crosslinking agent by an addition reaction. In addition, a release control agent such as MQ resin can be appropriately added to the thermosetting addition-type silicone-based release agent as needed.

[0068] Thermosetting silicone-based release agents typically use platinum-based catalysts as curing catalysts. Examples of platinum catalysts include chloroplatinic acid, platinum olefin complexes, and chloroplatinic acid olefin complexes.

[0069] Examples of silicone-modified urethane resins include copolymers of silicone monomers and / or polysiloxanes with urethane monomers and / or urethane oligomers. Commercially available silicone-modified urethane resins may also be used. Examples of commercially available products include the Dialomer™ SP series (e.g., SP-2105, SP-3035, etc.) manufactured by Dainichi Seika Kogyo Co., Ltd., which can be appropriately selected based on factors such as release properties and flexibility. Furthermore, if necessary, curing agents or other additives to increase the cohesive strength of the coating film may be appropriately added to the silicone-modified urethane resin.

[0070] The thickness of the release layer of the temporary support film is preferably in the range of 1 to 200 μm, more preferably in the range of 5 to 100 μm, and even more preferably in the range of 10 to 50 μm, from the viewpoints of release properties, ease of adhesion of mold protrusions to form through holes, and film formation of the release layer and manufacturing costs.

[0071] (Separator film) The adhesive tape of the present invention has a structure in which a separator film with a release treatment layer on one side is laminated on an adhesive layer. The separator film is to be peeled off when using the adhesive tape.

[0072] The separator film can be made of synthetic resins similar to those used for the temporary support film, such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyurethane. Among these, polyethylene terephthalate film is preferred from the viewpoint of heat resistance and strength. The thickness of the separator film is usually around 6 to 200 μm, and more preferably around 12 to 100 μm from the standpoint of handling and cost.

[0073] The release agent used in the release treatment layer of the separator film can be any conventionally known agent, such as a silicone-based release agent, a long-chain alkyl-based release agent, or a fluorine-based release agent. Among these, a silicone-based release agent is preferred, and can be appropriately selected depending on the release characteristics with respect to the adhesive layer.

[0074] The thickness of the release layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, and even more preferably 0.1 to 1 μm, from the viewpoint of release properties and thickness stability.

[0075] In this embodiment, it is preferable to cure the ionizing radiation-curable resin layer with a mold (mold member) having regularly spaced protrusions on its surface for forming through holes pressed against the ionizing radiation-curable resin layer before curing, thereby perforating through holes in the cured resin film to create an adhesive tape. As shown in Figure 2, the manufacturing process of the adhesive tape using the mold of this embodiment is as follows: First, in the ionizing radiation-curable resin lamination step (a), an ionizing radiation-curable resin composition is coated onto the surface of the release layer 60 of the temporary support film 50, forming a laminate 80 by laminating an ionizing radiation-curable resin layer 70. Next, in the mold penetration step (b), a mold 90 having regularly spaced protrusions 91 on its surface that are higher than the thickness of the ionizing radiation-curable resin layer 70 is pressed against the surface of the ionizing radiation-curable resin layer 70 of the laminate 80 that is not in contact with the temporary support film 50, causing the protrusions 91 to penetrate in the thickness direction of the ionizing radiation-curable resin layer 70. Next, in the curing step (c), the projection 91 penetrates the ionizing radiation-curable resin layer 70 and is irradiated with ionizing radiation to cure the ionizing radiation-curable resin layer 70. Furthermore, in the peeling and removal step (d), the mold 90 and the temporary support film 50 are peeled and removed to obtain a cured resin film 20 having through holes 21 in the thickness direction. Finally, in the adhesive layer lamination step (e), the cured resin film 20 is laminated to an adhesive layer 30, which is obtained by separately laminating an adhesive composition onto a separator film 40, to obtain the adhesive tape 10 of the present invention. [Examples]

[0076] The adhesive tape for laser dicing of the present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0077] <Preparation of temporary support film> A release layer coating solution was prepared by mixing 100 parts by mass of silicone-modified urethane resin (Diaromer SP-2105, manufactured by Dainichi Seika Kogyo Co., Ltd., with a non-volatile content of 20% by mass) and 15 parts by mass of isocyanate-based curing agent (Crossnate D-70, manufactured by Dainichi Seika Kogyo Co., Ltd., with a non-volatile content of 50% by mass). This solution was applied to one side of a 38 μm thick polyethylene terephthalate film to form a release layer with a dry film thickness of 15 μm. The film was then treated in a constant temperature bath at 45°C for 96 hours to obtain a temporary support film. <Preparing the separator film> A release agent coating solution, prepared by mixing 95 parts by mass of silicone release agent (KS-776A, manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts by mass of curing catalyst (CAT.PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.), and 500 parts by mass of toluene, was applied to one side of a 38 μm thick polyethylene terephthalate film at a dry weight of 0.3 g / m². 2 The film was coated in this manner, then dried and cured in a gear oven at 140°C for 1 minute to form a silicone release layer, which was then used to create a separator film.

[0078] <Preparation of mold (mold components)> [Mold 1]; Material: Quartz glass; Protrusion shape: Cylindrical (circular with a diameter of 50 μm, height of 90 μm); Protrusion arrangement: Square lattice arrangement with 100 μm spacing in the vertical and horizontal directions; Surface treatment: Fluorine-based silane coupling agent [Mold 2]; Material: Quartz glass; Protrusion shape: Cylindrical (circular with a diameter of 40 μm, height of 90 μm); Protrusion arrangement: Square lattice arrangement with 100 μm spacing vertically and horizontally; Surface treatment: Fluorine-based silane coupling agent [Mold 3]; Material: Quartz glass; Protrusion shape: Cylindrical (circular with a diameter of 60 μm, height of 90 μm); Protrusion arrangement: Square lattice arrangement with 100 μm spacing in the vertical and horizontal directions; Surface treatment: Fluorine-based silane coupling agent

[0079] <Preparation of ionizing radiation-curable resin coating solution> 36 parts by mass of triallyl isocyanurate (molecular weight 249, carbon-carbon double bond group: trifunctional) as a polyfunctional polymerizable compound, 64 parts by mass of 1,4-bis(3-mercaptobutyryloxy)butane (molecular weight 294.4, mercapto group: bifunctional) as a polyfunctional thiol compound, and 20 parts by mass of methyl ethyl ketone were mixed to prepare a coating solution for an ionizing radiation-curable resin layer.

[0080] <Preparation of adhesive layer coating solution> The following materials were used and mixed according to the following adhesive layer coating solution formulation to obtain the adhesive layer coating solution. [(meth)acrylic copolymer]; Ethyl acetate solution (non-volatile content 50%) of a copolymer of n-butyl acrylate and 2-hydroxyethyl acrylate (weight-average molecular weight 600,000, hydroxyl value 20 mg KOH / g) [Ionizing radiation polymerizable compound]; Urethane acrylate oligomer (acrylate hexafunctional, weight-average molecular weight 2,000) [Ionizing radiation polymerization initiator]; 1-Hydroxycyclohexylphenyl ketone [Isocyanate-based curing agent]; Ethyl acetate solution of tolylene diisocyanate-trimethylolpropane (TMP) adduct (75% non-volatile content) (Coating liquid for the adhesive layer) (meth)acrylic copolymer 75 parts by mass Ionizing radiation polymerizable compound 6 parts by mass Ionizing radiation polymerization initiator: 3 parts by mass Isocyanate-based curing agent: 5 parts by mass 11 parts by mass of ethyl acetate

[0081] (Example 1) <Preparation of cured resin film> An ionizing radiation-curable resin coating solution was applied to the release layer surface of the temporary support film so that the film thickness after drying would be 80 μm. The solvent was then dried to create a laminate consisting of the temporary support film and the ionizing radiation-curable resin layer. Next, the side of the mold 1 with the protrusions was pressed against the side of the ionizing radiation-curable resin layer of the laminate that was not in contact with the temporary support film. After confirming that the protrusions of the mold 1 penetrated the ionizing radiation-curable resin layer and that the protrusions were in close contact with the release layer of the temporary support film, ultraviolet irradiation (high-pressure mercury lamp, output 120 W / cm, integrated light amount 1000 mJ / cm) was performed from the temporary support film side. 2 After curing the ionizing radiation-curable resin layer, the mold 1 and the temporary support film were peeled off to produce a cured resin film having through holes in the mold 1. (Hole size of cured resin film: 0.0020 mm) 2 , open area ratio: 20%) <Making adhesive tape> The coating amount after drying is 15 g / m² on the release treatment layer surface of the separator film. 2 An adhesive layer coating liquid was applied to the surface of the adhesive layer, and the solvent was dried to form an adhesive layer. A cured resin film having through holes from the mold 1 was bonded to the surface of the adhesive layer, and the adhesive layer was cured and matured at 45°C for 48 hours to produce an adhesive tape.

[0082] (Example 2) In Example 1, an adhesive tape was prepared in the same manner as in Example 1, except that mold 1 was changed to mold 2. (Hole size of cured resin film: 0.0013 mm) 2 , open area ratio: 13%)

[0083] (Example 3) In Example 1, an adhesive tape was prepared in the same manner as in Example 1, except that mold 1 was changed to mold 3. (Hole size of cured resin film: 0.0028 mm) 2 , open area ratio: 28%)

[0084] (Comparative Example 1) In Example 1, in the production of the cured resin film, without using mold 1, a laminate consisting of a temporary support film and an ionizing radiation-curable resin layer was irradiated with ultraviolet light from the temporary support film side (high-pressure mercury lamp, output 120 W / cm, integrated light amount 1000 mJ / cm). 2 After curing the ionizing radiation-curable resin layer by performing the procedure described above, the temporary support film was peeled off to produce a cured resin film without through holes, and an adhesive tape was produced in the same manner as in Example 1. (Open area ratio of cured resin film: 0%)

[0085] (Comparative Example 2) In Example 1, instead of a cured resin film, a polypropylene film with a thickness of 80 μm that was perforated by laser processing (pore size of the base film: 0.50 mm) was used. 2 Using a material with an open-pore ratio of 20%, an adhesive tape was prepared in the same manner as in Example 1.

[0086] <Evaluation of chip scattering during dicing> SiC (silicon carbide) wafers were diced using the adhesive tapes of Examples 1-3 and Comparative Examples 1 and 2 under the following processing conditions, and chip breakage during processing was evaluated according to the following evaluation criteria. The evaluation results for each are shown in Table 1. (Processing conditions) Processing machine: Laser microjet dicing device Dicing speed: 50 mm / s Water jet diameter: 50 μm Water jet pressure: 40 MPa Laser wavelength: 532nm Wafer size: 8 inches Wafer thickness: 100 μm Tip size: 0.6mm x 0.6mm (Evaluation Criteria) ◎: Tip drop rate is less than 0% to 0.1% ○: Tip drop rate is 0.1% to less than 3% ×: Tip drop rate is 3% or higher

[0087] <Checking for damage or cuts to the substrate> After dicing the SiC wafer under the above conditions, the cut portion of the wafer was magnified with a microscope (50x) to check for damage to the substrate film and whether it was cut, and evaluated according to the following criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: No damage or / or cuts were observed in the base film. ×: Damage and / or cuts are visible in the base film.

[0088] <Evaluation of adhesive residue on chips> After dicing the SiC wafer under the above conditions, UV (ultraviolet) irradiation was performed from the substrate side of the adhesive tape (high-pressure mercury lamp, output 120 W / cm, integrated light intensity 500 mJ / cm). 2 The chips were then separated into individual pieces, 100 of which were peeled off the adhesive tape. The adhesive residue on the back of each chip (transfer of the adhesive layer) was visually inspected, and they were evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3, respectively. (Evaluation Criteria) ◎: No adhesive residue left on any of the tips. ○: 1-2 chips with adhesive residue ×: Three or more chips with adhesive residue.

[0089] [Table 1] [Explanation of symbols]

[0090] 10: Adhesive tape for laser dicing 20: Cured resin film 21: Through hole 30: Adhesive layer 40: Separator film 50: Temporary support film 60: Release layer 70: Ionizing radiation curable resin layer 80: Laminate 90: Mold 91: Protrusion

Claims

1. An adhesive tape for use in laser dicing in which a laser is guided by a water jet, wherein the adhesive tape comprises a base material and sequentially laminating an adhesive layer and a separator film on one surface of the base material, wherein the base material is a cured resin film obtained by curing an ionizing radiation-curable resin composition and having through holes in the thickness direction, wherein the cured resin film is a cured product obtained by addition curing an ionizing radiation-curable resin composition by an en-thiol reaction, wherein the polyfunctional polymerizable compound having two or more carbon-carbon double bonds in the molecule and a polyfunctional thiol compound, and the polyfunctional polymerizable compound is a polyfunctional allyl compound and the polyfunctional thiol compound is a polyfunctional secondary thiol compound.

2. A method for manufacturing an adhesive tape for laser dicing according to claim 1, comprising at least the following steps (a) to (e). (a) A step of forming a laminate by laminating an ionizing radiation-curable resin layer on a release layer of a temporary support film on which a release layer of silicone-modified urethane resin is formed, (b) A step of pressing a mold (mold member) having regularly spaced protrusions on its surface that are greater than the thickness of the ionizing radiation-curable resin layer against the surface of the laminate that is not in contact with the temporary support film of the ionizing radiation-curable resin layer, thereby penetrating the protrusions in the thickness direction of the ionizing radiation-curable resin layer. (c) A step of curing the ionizing radiation-curable resin layer by irradiating it with ionizing radiation while the protrusion penetrates the ionizing radiation-curable resin layer. (d) A step of peeling off the mold and the temporary support film to obtain a cured resin film having through holes in the thickness direction, (e) A step of laminating an adhesive layer and a separator film onto the cured resin film.

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