Adhesive Tape for Laser Dicing

Abstract

To provide an adhesive tape for laser dicing which is capable of performing dicing without damaging and cutting fibers of a mesh substrate even on a high-energy laser processing condition in laser dicing in which a laser is guided by a water jet, also prevents chip scattering or chip defects caused by a water flow and further prevents an adhesive layer from being transferred to a chip side (paste from remaining) when picking up an individualized chip.SOLUTION: The present invention relates to an adhesive tape for laser dicing comprising a substrate and an adhesive tape configured by successively laminating an adhesive layer and a separator film on one surface of the substrate. The adhesive layer consists of an adhesive composition containing at least a (meth)acrylic acid ester copolymer, a radiation-polymerizable initiator, a radiation-polymerizable compound, an isocyanate-based cross-linking agent and a hydroxyl group containing acrylic resin, and light transmittance in a wavelength of 532 nm is 85% or more.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 the semiconductor wafer with a laser guided by a water jet.

Background Art

[0002] Conventionally, as a method for dicing semiconductor wafers and semiconductor-related materials, a blade cutting method using a dicing blade rotated at high speed is generally used. In this method, during cutting, the cutting resistance by the blade directly acts on the semiconductor wafer, and chip scattering occurs where the chips fragmented by this cutting resistance fly off from the adhesive tape that is fixing them, or defects such as minute chipping and cracking of the chips occur, resulting in problems of reduced productivity and quality of semiconductor chips. In particular, in recent years, due to the demand for miniaturization and thinning of electronic devices, it has become an even more serious problem.

[0003] On the other hand, as one of the dicing methods that replaces the cutting technology of semiconductor wafers using a dicing blade, various dicing methods using a laser beam have been studied, and among them, there is a laser dicing method using a laser beam guided by a water jet.

[0004] When dicing a wafer by this method, since the cutting resistance by the blade does not directly act on the wafer as in the blade cutting method, the occurrence of defects such as chipping and cracking of the chips can be reduced. Also, since it is guided by a water jet, the wafer can be efficiently cooled and the thermal load can be reduced.

[0005] In the laser dicing method in which this laser is guided by a water jet, there is a problem that during dicing, pressure due to the water flow is applied to the adhesive surface of the adhesive tape that fixes the wafer, and the diced chips are likely to peel off from the adhesive tape. In response to this, Patent Document 1 proposes a water-permeable adhesive tape that uses a base material having water-permeable perforations in the support base material to prevent peeling due to water flow.

[0006] However, when using a non-woven fabric or a perforated base material as the water-permeable base material as in Patent Document 1, since the perforations are uneven or the perforation area cannot be increased, it becomes difficult for the water flow to permeate depending on the chip size and dicing conditions, and chip jumping may occur.

[0007] In contrast, Patent Document 2 states that by using a mesh base material for the water-permeable base material, the size of the holes and the opening area can be ensured to be relatively large compared to non-woven fabrics or perforated base materials, the water permeability is stable, and chip jumping and chip defects can be further reduced.

[0008] However, when dicing materials that are more difficult to cut than silicon wafers, such as silicon carbide (SiC) wafers used as power semiconductors, with higher energy, in a normal mesh base material, the mesh fibers absorb the laser light, damaging and cutting the base material, resulting in chip jumping.

[0009] In addition, the mesh base material is a mesh-like fabric formed of fibers, and since the contact area between the base material and the adhesive layer is small, the adhesion between the base material and the adhesive layer is not sufficient, and the adhesive layer may be peeled off from the base material by the water flow of the water jet, resulting in chip jumping and chip defects.

[0010] Furthermore, as the adhesive layer of the adhesive tape for fixing the wafer during dicing, a radiation-curable adhesive whose adhesive strength decreases upon irradiation with radiation is usually used for the purpose of improving the peelability of the chip. However, when picking up the diced chips, if the adhesive strength is decreased by radiation irradiation, the adhesion between the adhesive layer and the base material also decreases. In the case of a mesh base material with a small contact area with the adhesive layer, the adhesive layer is likely to peel off from the base material, and transfer (adhesive residue) to the chip side is likely to occur. [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-316648 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-117943 [Summary of the Invention] [Problems to be Solved by the Invention]

[0011] The present invention provides a laser dicing adhesive tape that can perform dicing without damaging or cutting the base material even when dicing with high energy, without causing chip flying due to water flow or chip defects in laser dicing guided by a water jet. Further, an object of the present invention is to provide a laser dicing adhesive tape in which the adhesive layer does not transfer (adhesive residue) to the chip side when picking up the diced chips. [Means for Solving the Problems]

[0012] A first invention is an adhesive tape used for laser dicing in which a laser is guided by a water jet, the adhesive tape comprising a base material, an adhesive layer and a separator film sequentially laminated on one surface of the base material, the base material being a mesh base material having openings formed by fibers, the adhesive layer being composed of an adhesive composition containing at least (meth)acrylate copolymer (A), radiation-polymerizable compound (B), radiation polymerization initiator (C), isocyanate crosslinking agent (D), and hydroxyl group-containing acrylic resin (E), and the light transmittance of the adhesive tape at a wavelength of 532 nm being 85% or more.

[0013] The second invention is the adhesive tape for laser dicing according to the first invention, wherein the material of the fiber forming the mesh base material is polyester or nylon, and the aperture ratio of the mesh base material is 25% to 75%.

[0014] The third invention is the adhesive tape for laser dicing according to the first or second invention, wherein the hydroxyl group-containing acrylic resin (E) in the adhesive composition has a hydroxyl value of 100 to 200 mgKOH / g and is contained in the solid content of the adhesive composition in an amount of 5% by mass or more and 35% by mass or less.

Advantages of the Invention

[0015] The adhesive tape for laser dicing of the present invention uses a mesh base material as a support base material, so that the water permeability of the water jet can be stably maintained, and chip jumping due to the water flow during dicing and defects such as chip chipping do not occur. Further, by setting the transmittance of the laser light with a wavelength of 532 nm used for wafer dicing to 85% or more, even when dicing with high energy, there is no damage to the base material or chip jumping due to cutting. Furthermore, by blending a hydroxyl group-containing acrylic resin in the radiation-curable adhesive layer composition, even if the adhesive force of the adhesive layer decreases due to radiation irradiation, the adhesion to the mesh base material can be ensured, and it is possible to provide an adhesive tape for laser dicing in which the adhesive layer does not transfer (adhesive residue) to the chip side during pickup of the diced chips.

Brief Description of the Drawings

[0016]

Figure 1

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described.

[0018] The adhesive tape for laser dicing of the present invention is formed by sequentially laminating a mesh base material, an adhesive layer, and a separator film. As an adhesive tape, the light transmittance at a wavelength of 532 nm of the laser light used for dicing a wafer is 85% or more. Thereby, even when dicing a material that is more difficult to cut than silicon (Si) such as silicon carbide (SiC) with high-energy laser light, the absorption of the laser light is small, and the fibers of the mesh base material are not damaged or cut. Further, as the adhesive layer, a radiation-curable adhesive is used to improve the peelability of the chip after dicing. By blending a hydroxyl group-containing acrylic resin in the radiation-curable adhesive composition, the adhesion to the fiber material is improved, and further, the adhesive layer easily penetrates in the thickness direction of the fiber, and the contact area between the fiber and the adhesive layer increases. Therefore, even if the adhesive strength decreases, the adhesion between the adhesive layer and the mesh base material can be ensured, and peeling of the adhesive layer can be prevented.

[0019] (Base material) As the base material constituting the adhesive tape for laser dicing of the present invention, a mesh base material which is a mesh-like fabric made of warp yarns and weft yarns is used. Examples of the weave of the fabric include mainly plain weave, twill weave, satin weave, etc. Plain weave is preferable in terms of high restraint force between warp yarns and weft yarns and excellent strength.

[0020] The light transmittance of the mesh base material is preferably 85% or more, more preferably 90% or more, of the light transmittance at a wavelength of 532 nm which is the wavelength of the laser light used for dicing the wafer. As the adhesive tape with the adhesive layer laminated, if the light transmittance at a wavelength of 532 nm of the laser light is 85% or more, even when dicing with high-energy laser light, the absorption of the laser light is small, and the fibers forming the mesh base material are not damaged or cut.

[0021] For the warp and weft yarns forming the mesh base material, it is preferable to use filament yarns with high strength. Examples of the fiber materials of the filament yarns include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyurethane, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyamide, acrylic, nylon and other synthetic fibers, natural fibers such as silk, metals such as stainless steel and brass, and inorganic fibers such as glass and carbon fiber. Among these fiber materials, synthetic fibers are preferable from the viewpoints of flexibility and processability, and among them, polyester or nylon is more preferable from the viewpoints of the transmissibility of the laser light used for dicing and the adhesion to the adhesive.

[0022] These fibers may be either monofilaments or multifilaments, but in order to have good transmissibility of laser light and make the size of the mesh openings uniform, it is preferable that they are monofilaments. The fiber diameter is preferably about 10 to 300 μm in diameter, and more preferably about 25 to 150 μm from the viewpoint of water permeability. Also, the aperture ratio of the mesh is preferably 15 to 85%, more preferably 25 to 75%. If the aperture ratio of the mesh is less than the above range, the water permeability will deteriorate and the chips will be easily peeled off by the water flow. On the other hand, if the aperture ratio exceeds the above range, the contact area with the adhesive layer will become very small, and it will be difficult to ensure the adhesion between the base material and the adhesive layer.

[0023] The thickness of the base material is preferably 10 to 400 μm, more preferably 30 to 250 μm, from the viewpoints of the processability, handleability of the adhesive tape, and the breakage and cuttability during dicing.

[0024] On the surface of the base material where the adhesive layer is laminated, surface treatments such as corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, primer treatment, etc. may be performed as necessary.

[0025] (Adhesive layer) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape for laser dicing of the present invention is composed of an acrylic radiation-curable pressure-sensitive adhesive composition. As the pressure-sensitive adhesive composition, it contains at least a (meth)acrylic acid ester copolymer (A), a radiation-polymerizable compound (B), a radiation polymerization initiator (C), an isocyanate-based crosslinking agent (D), and a hydroxyl group-containing acrylic resin (E). By blending the radiation-polymerizable compound (B), the adhesive strength can be reduced by radiation irradiation after dicing, and the peelability of the chip can be improved. Further, by blending the hydroxyl group-containing acrylic resin (E), the adhesion to the fiber material (polyester, nylon) of the mesh base material is increased, and the pressure-sensitive adhesive layer can easily penetrate in the thickness direction of the fiber, and the contact area between the fiber and the pressure-sensitive adhesive layer becomes large. Therefore, even if the adhesive strength is reduced, the adhesion between the pressure-sensitive adhesive layer and the mesh base material can be ensured, and the peeling of the pressure-sensitive adhesive layer during pickup can be prevented.

[0026] (Meth)acrylic acid ester copolymer (A) can be obtained, for example, by copolymerizing one or more (meth)acrylic acid alkyl esters having an alkyl group with 4 to 18 carbon atoms and one or more other copolymerizable monomers having an ethylenically unsaturated bond by a conventional method.

[0027] Examples of the (meth)acrylic acid alkyl ester 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, stearyl (meth)acrylate, and the like.

[0028] Examples of the monomer having a copolymerizable ethylenically unsaturated 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, fumaric acid, and the like.

[0029] (In the (meth) acrylate copolymer (A), as the monomer having a copolymerizable ethylenically unsaturated bond, a monomer having a functional group capable of reacting with a curing agent described later is used as an essential component. As the monomer having a functional group, monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate are particularly preferable.

[0030] (The weight average molecular weight (Mw) of the (meth) acrylate copolymer (A) is preferably from 10,000 to 1,000,000, more preferably from 200,000 to 800,000. When the weight average molecular weight is outside the above range, disadvantages such as a decrease in adhesive strength and difficulty in thermal decomposition may occur. The weight average molecular weight is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0031] (The (meth) acrylate copolymer (A) is the main component of the adhesive layer and is blended in the range of 40 to 80% by mass in the solid content of the adhesive composition.

[0032] The radiation-polymerizable compound (B) is, for example, a low-molecular-weight compound having at least two or more photopolymerizable carbon-carbon double bonds in a molecule that can be three-dimensionally crosslinked by light irradiation, and specifically, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, oligoester acrylate, etc. can be widely applied.

[0033] In addition to the acrylate-based compounds as described above, urethane acrylate-based oligomers can also be used. The urethane acrylate-based oligomers are obtained by reacting a polyol compound such as a polyester type or a polyether type with a polyvalent isocyanate compound (for example, 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 (for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.).

[0034] The blending amount of the radiation-polymerizable compound (B) is in the range of 5 to 50% by mass, more preferably 8 to 20% by mass, in the solid content of the pressure-sensitive adhesive composition. If it is out of the above range, there may be inconveniences such as it becoming difficult to reduce the adhesive force or the occurrence of adhesive residue.

[0035] As the radiation-polymerization initiator (C) is, for example, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxymethyl phenyl propane, etc. By adding at least one of these to the adhesive layer, the polymerization reaction can proceed efficiently. Here, the radiation mentioned means light rays such as ultraviolet rays or ionizing radiation such as electron beams.

[0036] The compounding amount of the radiation polymerization initiator (C) is 1 to 15% by mass, more preferably 3 to 10% by mass, based on the solid content of the adhesive composition.

[0037] The isocyanate-based curing agent (D) is used to adjust the adhesive force and cohesive force by reacting with the functional groups of the (meth)acrylate copolymer (A) in the adhesive composition and the hydroxyl groups of the hydroxyl group-containing acrylic resin (E). Examples of the isocyanate-based curing agent (D) include polyisocyanates, trimers of polyisocyanates, urethane prepolymers having isocyanate groups at the terminals obtained by reacting polyisocyanates with polyols, and polyisocyanate-based compounds having two or more isocyanate groups in one molecule such as trimers of the urethane prepolymers.

[0038] Examples of the polyisocyanate include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate, etc. The curing agent may be used alone or in combination of two or more.

[0039] The blending amount of the isocyanate-based curing agent (D) can be appropriately adjusted according to the required adhesive strength, but it is preferably 1 to 15% by mass, more preferably 1 to 10% by mass, based on the solid content of the adhesive composition.

[0040] Examples of the hydroxyl group-containing acrylic resin (E) include monomers of (meth)acrylic acid esters having one or more hydroxyl groups in the molecule, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 2,2-dihydroxymethylbutyl (meth)acrylate, polyhydroxyalkyl maleate, and polyhydroxyalkyl fumarate, and copolymers obtained by copolymerizing the monomers of the (meth)acrylic acid esters with another copolymerizable monomer.

[0041] Examples of the copolymerizable monomers include (meth)acrylic acid, alkyl (C1-C12) (meth)acrylate, maleic acid, alkyl maleate, fumaric acid, alkyl fumarate, itaconic acid, alkyl itaconate, styrene, α-methylstyrene, vinyl acetate, (meth)acrylonitrile, 3-(2-isocyanate-2-propyl)-α-methylstyrene, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and the like. By copolymerizing these monomers in the presence of a suitable solvent and a polymerization initiator, a hydroxyl group-containing acrylic resin can be obtained.

[0042] The hydroxyl value of the hydroxyl group-containing acrylic resin (E) is preferably in the range of 50 to 500 mgKOH / g, more preferably 80 to 350 mgKOH / g, and even more preferably 100 to 200 mgKOH / g. If the hydroxyl value is less than the above range, the adhesion between the adhesive layer and the fibers of the mesh substrate will not increase sufficiently, and the penetration of the adhesive layer into the fiber thickness direction will not increase either. Therefore, the adhesion between the adhesive layer and the substrate cannot be ensured, and the adhesive layer is likely to peel off from the substrate. On the other hand, if it exceeds the above range, the adhesive performance will decrease. Also, when forming the adhesive layer coating film, the coating film may be peeled off and the adhesive layer may not be formed.

[0043] The blending amount of the hydroxyl group-containing acrylic resin (E) is 3 to 50% by mass, more preferably 5 to 35% by mass, based on the solid content of the pressure-sensitive adhesive layer. If the blending amount is less than the above range, the adhesion between the pressure-sensitive adhesive layer and the fibers of the mesh base material will not increase sufficiently, and the pressure-sensitive adhesive layer will be easily peeled off from the base material during pickup. On the other hand, if it exceeds the above range, the adhesion performance will decrease. Also, when forming the pressure-sensitive adhesive layer coating film, the coating film may be repelled and the pressure-sensitive adhesive layer may not be formed.

[0044] The weight average molecular weight of the hydroxyl group-containing acrylic resin (E) is not particularly limited, but usually preferably in the range of 140 to 150,000, more preferably in the range of 1,000 to 100,000. If the weight average molecular weight is less than the above range, low molecular weight components may migrate to the adherend. On the other hand, if it exceeds the above range, the adhesion performance and the adhesion of the pressure-sensitive adhesive layer to the base material may decrease.

[0045] Various additives such as antioxidants, antistatic agents, leveling agents, and defoaming agents can be blended into the pressure-sensitive adhesive layer of the present invention as needed.

[0046] The coating amount of the pressure-sensitive adhesive layer is 5 to 50 g / m 2 or so, more preferably 10 to 30 g / m 2 in order to ensure the adhesive force and holding force to the adherend. If the coating amount of the pressure-sensitive adhesive layer is less than 5 g / m 2 , depending on the adhesive force to the adherend, the holding force in the shear direction cannot be ensured, and it is likely to be peeled off from the adherend. Also, when the coating amount of the pressure-sensitive adhesive layer exceeds 50 g / m 2 , the penetrability of the water jet water flow deteriorates, and the chip is likely to be peeled off. Also, the amount of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer increases, and the manufacturing cost rises.

[0047] As a method for forming the adhesive layer of the present invention, the adhesive composition as it is or as a coating liquid whose viscosity is adjusted with a solvent or the like is uniformly coated on the release-treated surface of a release-treated separator so as to have a predetermined thickness, and the solvent is dried to form an adhesive layer, and the adhesive tape of the present invention can be formed by laminating a mesh base material on the adhesive layer surface. Further, after laminating the mesh base material, by curing and aging the adhesive layer at room temperature or a predetermined temperature, penetration of the adhesive layer in the thickness direction of the fibers of the mesh base material is promoted, and the adhesive tape of the present invention can be obtained.

[0048] Examples of the coating method of the coating liquid of the adhesive layer of the present invention include a gravure coater, a bar coater, a comma knife coater, a die coater, a reverse coater, and the like.

[0049] The adhesive strength of the adhesive tape of the present invention is 1 N / 25 mm or more, more preferably 2 N / 25 mm or more. If the adhesive strength is low, the diced chips are likely to peel off. Further, when a radiation-curable adhesive is used, the adhesive strength after radiation irradiation is preferably less than 1 N / 25 mm, and further preferably less than 0.5 N / 25 mm. The lower the adhesive strength, the more defects such as chipping of the chips during pickup can be reduced. Here, the adhesive strength is the value measured when measuring the peeling force against the mirror surface of a silicon wafer under the conditions of a measurement temperature of 23 ± 3°C, a peeling angle of 180°, and a peeling speed of 300 mm / min.

[0050] (Separator film) The adhesive tape of the present invention has a structure in which a separator film having one surface release-treated is laminated on the adhesive layer. The separator film is peeled off when the adhesive tape is used.

[0051] Examples of the film material of the separator film include synthetic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, and polyurethane. Among them, polyethylene terephthalate film is preferred from the viewpoints of heat resistance and strength. The thickness of the separator film is usually about 6 to 200 μm, and more preferably about 12 to 100 μm from the viewpoints of handleability and cost.

[0052] As the release agent used for the release treatment of the separator film, conventionally known ones such as silicone-based release agents, long-chain alkyl-based release agents, and fluorine-based release agents can be used. Among these, it is preferable to use a silicone-based release agent that is relatively inexpensive and provides stable releasability.

[0053] As the silicone-based release agent, a thermosetting silicone-based release agent can be preferably used. The thermosetting silicone-based release agent is, for example, a silicone composition composed of a polyorganosiloxane having two or more alkenyl groups in one molecule and an organohydrogenpolysiloxane as a crosslinking agent, which is cured by an addition reaction. Further, a release control agent such as an MQ resin can be added to the thermosetting silicone-based release agent as necessary.

[0054] For the thermosetting silicone-based release agent, a platinum-based catalyst is usually used as a curing catalyst. Examples of the platinum catalyst include chloroplatinic acid, an olefin complex of platinum, and an olefin complex of chloroplatinic acid.

[0055] The thickness of the release treatment 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 viewpoints of releasability and thickness stability.

Examples

[0056] Examples and comparative examples are shown below to explain the adhesive tape for laser dicing of the present invention in detail, but the present invention is not limited to these examples.

[0057] <Preparation of Separator Film 1> A release agent coating solution prepared by mixing 95 parts by mass of a silicone release agent (KS-776A manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts by mass of a crosslinking agent (CAT.PL-50T manufactured by Shin-Etsu Chemical Co., Ltd.), and 500 parts by mass of toluene was applied onto one side of a polyethylene terephthalate film with a thickness of 38 μm so that the dry weight was 0.3 g / m 2 and then dried and cured in a gear oven at 140 °C for 1 minute to form a silicone release treatment layer, thereby obtaining Separator Film 1.

[0058] <Base Material for Adhesive Tape to be Used> [Mesh Base Material 1]: Nylon fiber, monofilament, plain weave, fiber diameter: 100 μm, mesh opening: 150 μm, aperture ratio: 36%, light transmittance (wavelength 532 nm): 95% [Mesh Base Material 2]: Polyester fiber, monofilament, plain weave, fiber diameter: 48 μm, mesh opening: 140 μm, aperture ratio: 55%, light transmittance (wavelength 532 nm): 90% [Mesh Base Material 3]: Nylon fiber, monofilament, plain weave, fiber diameter: 50 μm, mesh opening: 50 μm, aperture ratio: 25%, light transmittance (wavelength 532 nm): 88% [Mesh Base Material 4]: Nylon fiber, monofilament, plain weave, fiber diameter: 40 μm, mesh opening: 260 μm, aperture ratio: 75%, light transmittance (wavelength 532 nm): 98% [Mesh Base Material 5]: Polyester fiber, monofilament, plain weave, fiber diameter: 50 μm, mesh opening: 50 μm, aperture ratio: 25%, light transmittance (wavelength 532 nm): 75% [Mesh Base Material 6]: SUS fiber, monofilament, plain weave, fiber diameter: 40 μm, mesh opening: 80 μm, aperture ratio: 44%, light transmittance (wavelength 532 nm): 50% The aperture ratio of the mesh base material is the value calculated by the following formula. Aperture ratio = (mesh opening) 2 ÷ (mesh opening + fiber diameter) 2

[0059] <Adjustment of Adhesive Layer Coating Solution> Using the (meth)acrylic acid ester copolymer, radiation-polymerizable compound, radiation polymerization initiator, isocyanate curing agent, and hydroxyl group-containing acrylic resin shown below, pressure-sensitive adhesive layer coating liquids 1 to 7 were prepared according to the formulations in Table 1. [(Meth)acrylic acid ester copolymer]: Ethyl acetate solution (nonvolatile content 50%) of a copolymer of n-butyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 600,000, hydroxyl value 20 mgKOH / g) [Radiation-polymerizable compound]: Urethane acrylate oligomer (acrylate 6-functional, weight average molecular weight 2,000) [Radiation polymerization initiator]: 1-Hydroxycyclohexyl phenyl ketone [Isocyanate curing agent]: Ethyl acetate solution (nonvolatile content 75%) of a tolylene diisocyanate-trimethylolpropane (TMP) adduct [Hydroxyl group-containing acrylic resin 1]: Copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate (weight average molecular weight 2,500, hydroxyl value 120 mgKOH / g) [Hydroxyl group-containing acrylic resin 2]: Copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate (weight average molecular weight 70,000, hydroxyl value 200 mgKOH / g) [Hydroxyl group-containing acrylic resin 3]: Copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate (weight average molecular weight 13,000, hydroxyl value 50 mgKOH / g) [Hydroxyl group-containing acrylic resin 4]: Copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate (weight average molecular weight 15,000, hydroxyl value 250 mgKOH / g)

[0060]

Table 1

[0061] (Example 1) On the silicone release-treated surface of separator film 1, the coating amount of the pressure-sensitive adhesive layer after drying was 15 g / m 2The adhesive layer coating liquid 1 was applied so as to achieve [the required state], and after the solvent was heated and dried, the mesh base material 1 was bonded to the adhesive layer surface, and cured and aged at 45 °C for 48 hours to obtain an adhesive tape.

[0062] (Example 2) An adhesive tape was obtained in the same manner as in Example 1, except that the mesh base material 1 bonded to the adhesive layer was changed to the mesh base material 2.

[0063] (Example 3) An adhesive tape was obtained in the same manner as in Example 1, except that the mesh base material 1 bonded to the adhesive layer was changed to the mesh base material 3.

[0064] (Example 4) An adhesive tape was obtained in the same manner as in Example 1, except that the mesh base material 1 bonded to the adhesive layer was changed to the mesh base material 4.

[0065] (Example 5) An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 2.

[0066] (Example 6) An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 3.

[0067] (Example 7) An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 4.

[0068] (Example 8) An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 5.

[0069] (Example 9) An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 6.

[0070] (Comparative Example 1) In Example 1, an adhesive tape was obtained in the same manner as in Example 1, except that the mesh substrate 1 bonded to the adhesive layer was changed to the mesh substrate 5.

[0071] (Comparative Example 2) In Example 1, an adhesive tape was obtained in the same manner as in Example 1, except that the mesh substrate 1 bonded to the adhesive layer was changed to the mesh substrate 6.

[0072] (Comparative Example 3) In Example 1, an adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid 1 was changed to the adhesive layer coating liquid 7.

[0073] (Measurement of Light Transmittance) Samples of 5 cm square were cut out from each of the adhesive tapes obtained in Examples 1 to 9 and Comparative Examples 1 to 3. After peeling off the separator film, the light transmittance of the adhesive tape at a wavelength of 532 nm was measured using an ultraviolet-visible spectrophotometer (light source: halogen lamp). The measurement results are shown in Tables 2 and 3, respectively.

[0074] (Evaluation of Chip Ejection during Dicing) Using each of the adhesive tapes of Examples 1 to 9 and Comparative Examples 1 to 3, a SiC (silicon carbide) wafer was diced under the following processing conditions, and the chip ejection during processing was evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3, respectively. (Processing Conditions) Processing machine: Laser microjet dicing apparatus Dicing speed: 50 mm / s Water jet diameter: 50 μm Water jet pressure: 40 MPa Laser wavelength: 532 nm Wafer size: 8 inches Wafer thickness: 100 μm Chip size: 0.6 mm × 0.6 mm (Evaluation Criteria) ◎: Chip ejection rate is 0% to less than 0.1% ○: Chip flying rate is 0.1% to less than 3% ×: Chip flying rate is 3% or more

[0075] <Confirmation of substrate damage and cutting> After dicing the SiC wafer under the above conditions, the cut part of the wafer was magnified with a microscope (50 times) to check for damage and cutting of the fibers of the mesh substrate, and evaluated according to the following criteria. The evaluation results are shown in Table 2 and Table 3 respectively. (Evaluation criteria) ○: No damage and / or cutting of the substrate fibers is observed. ×: Damage and / or cutting of the substrate fibers is observed.

[0076] <Evaluation of adhesive residue on chips> After dicing the SiC wafer under the above conditions, UV (ultraviolet) irradiation (high-pressure mercury lamp, output 120 W / cm, integrated light quantity 500 mJ / cm 2 ) was performed, 100 individual chips were peeled off from the adhesive tape, and the adhesive residue (transfer of the adhesive layer) on the back surface of the chips was visually confirmed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2 and Table 3 respectively. (Evaluation criteria) ◎: No adhesive residue on all chips ○: 1 to 2 chips with adhesive residue ×: 3 or more chips with adhesive residue

[0077]

Table 2

[0078]

Table 3

Explanation of symbols

[0079] 1: Adhesive tape for laser dicing 2: Mesh substrate 2a: Fibers of the mesh substrate 3: Adhesive layer 4: Separator film

Claims

1. An adhesive tape used for laser dicing in which a laser is guided by a water jet, the adhesive tape comprising a base material, an adhesive layer and a separator film sequentially laminated on one surface of the base material, the base material being a mesh base material having openings formed of fibers, the adhesive layer being composed of an adhesive composition containing at least a (meth)acrylate copolymer (A), a radiation-polymerizable compound (B), a radiation polymerization initiator (C), an isocyanate-based crosslinking agent (D), and a hydroxyl group-containing acrylic resin (E), and the light transmittance of the adhesive tape at a wavelength of 532 nm being 85% or more. An adhesive tape for laser dicing, characterized in that it is as described above.

2. The adhesive tape for laser dicing according to Claim 1, wherein the material of the fibers forming the mesh base material is polyester or nylon, and the aperture ratio of the mesh base material is 25% to 75%.

3. The hydroxyl group-containing acrylic resin (E) in the adhesive composition has a hydroxyl value of 100 to 200 mgKOH / g and is contained in an amount of 5% by mass or more and 35% by mass or less in the solid content of the adhesive composition. The adhesive tape for laser dicing according to Claim 1 or Claim 2, characterized in that it is as described above.

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