Cutting tape

Abstract

Provided is a dicing tape that can properly hold a wafer and prevent a reduction in yield due to wafer contamination by an adhesive even when used in the manufacture of a semiconductor wafer including a solvent cleaning process. The dicing tape of the present invention comprises: a substrate and an adhesive layer disposed on one side of the substrate, and the dicing tape is used in a method for manufacturing a semiconductor wafer including a solvent cleaning process. The isopropyl alcohol eluate of the adhesive layer is 5 mg or less.

Description

Technical Field

[0001] The present invention relates to cutting tapes. Background Art

[0002] For a workpiece (e.g., a semiconductor wafer) that is a collection of electronic components, after being manufactured with a large diameter and patterned on the surface, the back side is usually ground to a thickness of about 100 μm to 600 μm, and then cut and separated (diced) into small pieces of components, and then moved to the installation process. In this dicing process, the workpiece is cut and diced. In the manufacturing process of semiconductors, an adhesive sheet (e.g., Patent Document 1) is used to fix the semiconductor wafer and the dicing frame (e.g., SUS ring) used in the dicing process.

[0003] Semiconductor wafers are sometimes processed into thin shapes by a back grinding process, whereby their strength is reduced, and cracks and / or warping are generated in the wafer. Furthermore, it is also difficult to handle a wafer with reduced strength. Therefore, glass, hard plastic, etc., which are supporting materials, are sometimes attached to the wafer in advance and a back grinding process is performed to ensure the strength of the wafer. The supporting material can be attached to the wafer using, for example, an adhesive composition or an adhesive tape. The supporting material can support the wafer during the back grinding process and the back wiring and bump formation process. Thereafter, the wafer is attached to an adhesive sheet (for example, a dicing tape), and after the supporting material is peeled off, it is provided for the cutting process. Therefore, as an adhesive for bonding the supporting material, an adhesive that can be easily peeled off after the back grinding process is proposed (for example, patent document 1). In the case where an adhesive is usually used to attach the supporting material, the supporting material is peeled off by dissolving the adhesive using a solvent. However, the cleaning (dissolving the adhesive) process using the solvent has the problem that the adhesive force of the adhesive tape (dicing tape) is reduced and the wafer cannot be fully held. In addition, there is also the problem that the adhesive dissolved by the solvent causes contamination of the wafer and the yield rate is reduced.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-007646

[0007] Patent Document 2: Japanese Patent Application Publication No. 2014-37458 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The present invention is made to solve the above-mentioned conventional problems and provides a dicing tape which can appropriately hold the wafer and prevent a reduction in yield due to wafer contamination by an adhesive even when used in the manufacture of semiconductor wafers including a solvent cleaning process.

[0010] Solutions for solving problems

[0011] The dicing tape of the present invention comprises: a substrate and an adhesive layer disposed on one side of the substrate, and the dicing tape is used in a method for manufacturing a semiconductor wafer including a solvent cleaning step. The isopropyl alcohol eluate of the adhesive layer is 5 mg or less.

[0012] In one embodiment, the composition forming the pressure-sensitive adhesive layer contains an additive having a weight average molecular weight of 5,000 or more.

[0013] In one embodiment, the content of the additive is 5 to 100 parts by weight based on 100 parts by weight of the base polymer of the adhesive.

[0014] In one embodiment, the dicing tape of the present invention is used by being bonded to an adherend having an uneven surface.

[0015] In one embodiment, the adherend having a concavo-convex surface is a TSV wafer.

[0016] Effects of the Invention

[0017] The dicing tape of the present invention comprises: a substrate and an adhesive layer disposed on one side of the substrate, wherein the isopropyl alcohol elution of the adhesive layer is 5 mg or less. By using such a dicing tape, a dicing tape can be provided that can properly hold the wafer and prevent the reduction of the yield rate due to wafer contamination of the adhesive even when used in the manufacture of semiconductor wafers including a solvent cleaning process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic cross-sectional view of a dicing tape according to one embodiment of the present invention.

[0019] Description of Reference Numerals

[0020] 10. Base material

[0021] 20 adhesive layers

[0022] 100 cutting tape DETAILED DESCRIPTION

[0023] A. Overview of cutting tape

[0024] Figure 1Schematic cross-sectional view of a dicing tape according to one embodiment of the present invention. The dicing tape 100 shown in the figure comprises: a substrate 10, and an adhesive layer 20 disposed on one surface of the substrate 10. The adhesive layer is typically formed of an active energy ray-curable adhesive composition. In practice, in order to properly protect the adhesive layer 20 until use, a separator is temporarily adhered to the adhesive layer 20 in a removable manner. In addition, the dicing tape 100 may also include any other appropriate layers. Preferably, the adhesive layer is directly disposed on the substrate.

[0025] In another embodiment of the present invention, the adhesive layer has a two-layer structure, and the dicing tape includes a substrate, a first adhesive layer, and a second adhesive layer (not shown) in this order.

[0026] The dicing tape of the present invention is used in a method for manufacturing semiconductor wafers including a solvent cleaning process. In the solvent cleaning process, cleaning based on a hydrophobic organic solvent (e.g., d-limonene) for removing the adhesive used in attaching the support material and cleaning based on a hydrophilic solvent (e.g., isopropyl alcohol) for removing the organic solvent are performed. The isopropyl alcohol elution of the adhesive layer 20 is 5 mg or less, preferably 4 mg or less, and more preferably 3 mg or less. By making the isopropyl alcohol elution of the adhesive layer 20 less than 5 mg, even in the case of the manufacture of semiconductor wafers including a solvent cleaning process, the wafer can be properly maintained and the reduction in yield caused by wafer contamination of the adhesive can be prevented. The less the isopropyl alcohol elution of the adhesive layer, the better, for example, it can be 0 mg. In this specification, the isopropyl alcohol elution of the adhesive layer refers to the value measured by the following method. A SUS ring with an inner diameter of 75 mm (inner diameter: 44.2 cm 2 ) is attached to the adhesive layer of the dicing tape, 4 ml of isopropyl alcohol is added to the inner side of the SUS ring, and it is left to stand for 30 minutes. Thereafter, the isopropyl alcohol is recovered in a glass bottle whose weight has been measured in advance. Next, the glass bottle is heated at 130°C for 3 hours, dried at 180°C for 1 hour, and the weight of the glass bottle is measured. The value obtained by subtracting the weight of the heated glass bottle from the weight of the glass bottle before heating (before isopropyl alcohol is recovered) is taken as the weight (mg) of the eluted matter.

[0027] The initial adhesive force at 23°C when the dicing tape of the present invention is attached to a stainless steel plate is preferably 0.2N / 20mm to 10N / 20mm, and more preferably 0.5N / 20mm to 6N / 20mm. In this specification, the adhesive force refers to the value measured in accordance with JISZ0237:2000. Specifically, it refers to the following value: the dicing tape is attached to a stainless steel plate (arithmetic mean surface roughness Ra: 50±25nm) by making a 2kg roller reciprocate once, and after being placed at 23°C for 30 minutes, the dicing tape is peeled off under the conditions of a peeling angle of 180° and a peeling speed (tensile speed) of 300mm / min. In this specification, "initial adhesive force" refers to the adhesive force before irradiation with active energy rays.

[0028] In one embodiment, a dicing tape was attached to a silicon mirror wafer and irradiated with 460 mJ / cm 2 The adhesive strength at 23°C after ultraviolet irradiation is preferably 0.01N / 20mm to 0.3N / 20mm, and more preferably 0.02N / 20mm to 0.2N / 20mm. In such a range, a dicing tape can be obtained in which the adhesive strength is reduced by ultraviolet irradiation after dicing, thereby facilitating the picking up of small-piece workpieces (for example, semiconductor chips). The above-mentioned ultraviolet irradiation is, for example, an ultraviolet irradiation device (manufactured by Nitto Seiki Co., Ltd., trade name "UM-810") to irradiate the adhesive layer with ultraviolet rays from a high-pressure mercury lamp (characteristic wavelength: 365nm, cumulative light amount: 460mJ / cm 2 , Irradiation energy: 70W / cm 2 )6.6 seconds to perform.

[0029] The thickness of the dicing tape is preferably 35 μm to 500 μm, more preferably 60 μm to 300 μm, and further preferably 80 μm to 200 μm.

[0030] The total light transmittance of the dicing tape is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. By using such a dicing tape, it can also be suitable for use in a manufacturing process of a semiconductor wafer including a stealth dicing process. The total light transmittance of the dicing tape is, for example, 98% or less, preferably 99% or less.

[0031] The transmittance of the light of wavelength 1064nm of the dicing tape is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. In such a range, it can also be suitable for use in the manufacturing process of semiconductor wafers including the stealth dicing process. The transmittance of the light of wavelength 1064nm of the dicing tape is, for example, 98% or less, preferably 99% or less.

[0032] The haze value of the dicing tape is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. When it is within this range, it can also be suitably used in the manufacturing process of semiconductor wafers including the stealth dicing process. The haze value of the dicing tape is, for example, 1% or more.

[0033] B. Base material

[0034] The substrate 10 may be made of any appropriate resin. Examples of the resin include polyethylene resins, polypropylene resins, polybutene resins, polymethylpentene resins and other polyolefin resins, polyurethane resins, polyester resins, polyimide resins, polyetherketone resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicon resins, cellulose resins, ionomer resins, etc. Polyolefin resins are preferred.

[0035] In one embodiment, the substrate includes a polyethylene resin. Examples of the polyethylene resin include low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, and ultra-low-density polyethylene.

[0036] In the polyethylene resin, the content ratio of the structural unit derived from ethylene is preferably 80 mol% or more, more preferably 90 mol% or more, and further preferably 95 mol% or more. As structural units other than structural units derived from ethylene, structural units derived from monomers copolymerizable with ethylene can be listed, for example, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. can be listed.

[0037] The content of the polyethylene resin is preferably 80% by weight or more, more preferably 85% by weight to 100% by weight, and even more preferably 95% by weight to 100% by weight of the resin forming the substrate.

[0038] The substrate may further contain any appropriate additives, such as lubricants, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, colorants, and the like.

[0039] In one embodiment, one surface of the substrate is preferably embossed. It is preferred that only one surface of the substrate is embossed and the embossed surface is used as the surface on the adhesive layer side. By embossing the surface on the adhesive layer side, the adhesion between the adhesive layer and the substrate can be improved. The arithmetic mean surface roughness Ra (JISB0601) of the unembossed surface of the substrate is preferably less than 1.0 μm, more preferably less than 0.8 μm, further preferably less than 0.5 μm, and particularly preferably 0.01 μm to 0.5 μm. In addition, the arithmetic mean surface roughness Ra (JISB0601) of the embossed surface of the substrate is preferably 1.0 μm to 3 μm, more preferably 1.4 μm to 2 μm. If the arithmetic mean surface roughness Ra of the embossed surface of the substrate exceeds 3 μm, there is a concern that it becomes easy to generate gaps between the adhesive layer and the substrate. In addition, if the Ra is less than 1 μm, there is a concern that adhesion occurs when the substrate is stored.

[0040] The thickness of the substrate is preferably 30 μm to 300 μm, more preferably 53 μm to 200 μm, and even more preferably 70 μm to 160 μm.

[0041] The total light transmittance of the substrate is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, particularly preferably 95% or more, and preferably 98% or less, more preferably 99% or less.

[0042] The tensile modulus of the substrate at 22°C is preferably 50 MPa to 120 MPa, more preferably 70 MPa to 90 MPa. In such a range, a dicing tape with excellent expansibility can be obtained. The tensile modulus of the substrate is measured using a tensile tester (manufactured by SHIMADZU Co., Ltd., "AG-IS") under the conditions of a chuck distance of 50 mm, a tensile speed of 300 mm / min, and a substrate width of 10 mm.

[0043] C. Adhesive layer

[0044] The adhesive layer 20 is formed using a composition (adhesive composition) for forming the adhesive layer. As described above, the isopropanol dissolution of the adhesive layer is less than 5 mg. By making the isopropanol dissolution of the adhesive layer less than 5 mg, a dicing tape can be provided that can properly hold the wafer and prevent the wafer contamination of the adhesive from causing a reduction in yield even when used in a manufacturing process of a semiconductor wafer including a solvent cleaning process.

[0045] C-1. Adhesive composition

[0046] As the adhesive composition (adhesive), any appropriate adhesive may be used, and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, and polyvinyl ether adhesives.

[0047] In one embodiment, the adhesive composition is preferably an active energy ray-curable adhesive composition. By using an active energy ray-curable adhesive, the adhesive strength can be reduced by irradiation with active energy rays (representatively ultraviolet rays) after dicing, thereby making it easy to pick up the small-piece workpiece (for example, a semiconductor chip).

[0048] C-1-1. Base polymer

[0049] The adhesive composition may include a base polymer that exhibits adhesiveness. As monomers constituting the base polymer, for example, hydrophilic monomers may be cited. As the hydrophilic monomer, any appropriate monomer having a polar group may be used. Specifically, carboxyl-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyl-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate; styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylic acid, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate; Sulfonic acid group-containing monomers such as acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, (meth)acrylamide sulfonyl ester, (meth)acryloxynaphthalenesulfonic acid, etc.; phosphate group-containing monomers such as 2-hydroxyethylacryl phosphate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-methylolpropane (meth)acrylamide, acryloyl morpholine, etc. (N-substituted) amide monomers; (meth)acrylamide aminoethyl ester, (meth)acrylamide N,N-dimethylaminoethyl ester, tert-butylaminoethyl ester, etc. alkyl ester monomers; (meth) acrylate methoxyethyl, (meth) acrylate ethoxyethyl (meth) acrylate and other (meth) acrylate alkoxyalkyl ester monomers; N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and other maleimide monomers; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide and other itaconimide monomers; N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl Succinimide monomers such as 6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide, etc.; vinyl monomers such as vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N-vinyl carboxylic acid amides, styrene, α-methyl styrene, N-vinyl caprolactam, etc.; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate;Diol acrylate monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylate monomers having heterocyclic rings, halogen atoms, silicon atoms, etc. such as tetrahydrofurfuryl (meth)acrylate, fluoro(meth)acrylate, and silicon (meth)acrylate; polyfunctional monomers such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate. As the hydrophilic monomer, a hydroxyl-containing monomer and / or an (N-substituted)amide monomer can be appropriately used. The hydrophilic monomer can be used alone or in combination of two or more. ;

[0050] Furthermore, the above-mentioned hydrophilic monomer and hydrophobic monomer may be used in combination. As the hydrophobic monomer, any appropriate monomer may be used as long as it is a monomer having hydrophobicity. Specifically, vinyl alkyl or aryl ethers having an alkyl group having 9 to 30 carbon atoms, such as vinyl 2-ethylhexanoate, vinyl laurate, vinyl stearate, and stearyl vinyl ether; alkyl esters of (meth)acrylic acid having 6 to 30 carbon atoms, such as hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl acrylate, isononyl acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate; unsaturated vinyl esters of (meth)acrylic acid derived from fatty acids and aliphatic alcohols; monomers derived from cholesterol; olefin monomers, such as 1-butene, 2-butene, 1-pentene, 1-hexene, 1-octene, isobutylene, and isoprene. The hydrophobic monomer may be used alone or in combination of two or more. It should be noted that the hydrophobic monomer used in the present invention refers to a monomer having a solubility of 0.02 g or less in 100 g of water.

[0051] The base polymer may further include monomer components other than the hydrophilic monomer and the hydrophobic monomer. Other monomer components include alkyl acrylates such as butyl acrylate and ethyl acrylate. Other monomer components may be used alone or in combination of two or more.

[0052] The above-mentioned base polymer may further contain a structural unit derived from an isocyanate compound having a curable functional group in the molecule. The base polymer containing a structural unit derived from an isocyanate compound can be obtained, for example, by reacting a substituent (for example, an OH group) possessed by the structural unit derived from the above-mentioned hydrophilic monomer with an NCO group of the isocyanate compound. As the above-mentioned isocyanate compound, for example, methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc. can be cited.

[0053] The weight average molecular weight of the base polymer constituting the above-mentioned binder is preferably 300,000 to 2,000,000, and more preferably 500,000 to 1,500,000. The weight average molecular weight can be measured by GPC (solvent: THF).

[0054] C-1-2. Additives with a weight average molecular weight of 5,000 or more

[0055] The adhesive composition preferably includes an additive having a weight average molecular weight of 5000 or more. By including such an additive, the amount of isopropanol elution of the adhesive layer can be reduced. In addition, even in the case where the adherend has a concave-convex surface (for example, a TSV wafer), the adhesive layer is in close contact with the recessed portion and can fully maintain the adherend. The weight average molecular weight of the additive is preferably more than 7000, more preferably more than 8000, and further preferably more than 10000. In addition, the weight average molecular weight of the additive is preferably less than 70000, and further preferably less than 50000. The weight average molecular weight of the additive can be measured, for example, by GPC (solvent: THF).

[0056] As an additive having a weight average molecular weight of 5000 or more, for example, any appropriate polymer or oligomer can be used. Specifically, active energy ray reactive oligomers, thermosetting oligomers, etc. can be listed. Active energy ray reactive oligomers are preferred. Such additives can be used alone or in combination of two or more.

[0057] Examples of active energy ray-reactive oligomers include urethane acrylate oligomers, epoxy (meth)acrylate oligomers, and acrylic (meth)acrylate oligomers. Urethane acrylate oligomers and acrylic (meth)acrylate oligomers are preferably used.

[0058] As the active energy ray-reactive oligomer, commercially available products may be used, for example, UV-3000B (weight average molecular weight: 18,000) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., ARONIX M321 (weight average molecular weight: 10,000) manufactured by Toagosei Co., Ltd., etc. may be mentioned.

[0059] As the thermosetting oligomer, for example, any appropriate oligomer having at least one thermosetting functional group such as a glycidyl group, a carboxyl group, a hydroxyl group, or an amino group can be used.

[0060] As described above, in one embodiment of the present invention, the adhesive layer has a two-layer structure. In the case of a dicing tape having such a two-layer adhesive layer, at least the second adhesive layer (adhesive layer in contact with the adherend) may contain an additive having a weight average molecular weight of 5,000 or more.

[0061] C-1-3. Polymerization initiator

[0062] The active energy ray-curable adhesive composition typically includes a polymerization initiator. As the polymerization initiator, any appropriate initiator can be used, and a photopolymerization initiator is preferably used. As the photopolymerization initiator, any appropriate initiator can be used. As the photopolymerization initiator, for example, α-keto alcohol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α, α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenylketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinylpropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisole methyl ether; benzyl dimethyl Ketal compounds such as ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)oxime; benzophenone compounds such as benzoylbenzoic acid and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketone; acylphosphine oxide; acylphosphonate, etc. The photopolymerization initiator may be used alone or in combination of two or more. The amount of the photopolymerization initiator may be set to any appropriate amount. The amount of the photopolymerization initiator used is preferably 1 to 10 parts by weight, more preferably 3 to 7 parts by weight, based on 100 parts by weight of the base polymer.

[0063] As the photopolymerization initiator, a commercially available product may be used, and examples thereof include trade names "Irgacure 651", "Irgacure 184", "Irgacure 369", "Irgacure 819", and "Irgacure 2959" manufactured by BASF Corporation.

[0064] C-1-4. Cross-linking agent

[0065] The active energy ray-curable adhesive composition preferably further comprises a crosslinking agent. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, carbodiimide crosslinking agents, and amine crosslinking agents.

[0066] In one embodiment, an isocyanate crosslinking agent is preferably used. An isocyanate crosslinking agent is preferred because it can react with a variety of functional groups. Specific examples of the isocyanate crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; isocyanate adducts such as trimethylolpropane / toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "CORONATE L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HL"), and isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"); and the like. It is preferable to use a cross-linking agent having three or more isocyanate groups.

[0067] The active energy ray-curable adhesive composition may further include any appropriate additives. As additives, for example, active energy ray polymerization accelerators, free radical scavengers, tackifiers, plasticizers (for example, trimellitate plasticizers, pyromellitate plasticizers), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release regulators, softeners, surfactants, flame retardants, antioxidants, etc. can be listed.

[0068] The content of the crosslinking agent can be adjusted to any appropriate amount. For example, it is 0.005 to 20 parts by weight, preferably 0.02 to 10 parts by weight, relative to 100 parts by weight of the base polymer. In addition, when the adhesive layer is a single-layer structure, the content ratio of the crosslinking agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, relative to 100 parts by weight of the base polymer of the adhesive. In such a range, an adhesive layer with an appropriately adjusted elastic modulus can be formed.

[0069] C-2. Single-layer adhesive layer

[0070] In one embodiment, the adhesive layer is composed of a single layer. When the adhesive layer is composed of a single layer, the tensile elastic modulus of the above-mentioned adhesive layer at 22°C is preferably 0.05MPa to 1MPa, more preferably 0.1MPa to 0.8MPa, and further preferably 0.15MPa to 0.6MPa. When it is in such a range, an adhesive layer with sufficient strength can be formed, and the adhesive layer and the substrate are well in close contact, so that the generation of voids near the interface between the substrate and the adhesive layer can be suppressed. In particular, when a substrate with an embossed surface on the side of the adhesive layer is used, voids are usually easy to generate. By setting the tensile elastic modulus of the adhesive layer to the above range, the generation of voids can be suppressed. If the tensile elastic modulus exceeds 1MPa, there is a concern that the adhesive layer does not follow the concave and convex of the substrate when the adhesive layer is laminated on the embossed surface of the substrate. In addition, when the tensile elastic modulus is less than 0.05MPa, there is a concern that the adhesive layer does not maintain a fixed shape and does not have sufficient characteristics. When the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive as described above, the tensile modulus at 22° C. before irradiation with active energy rays is preferably within this range. The method for measuring the tensile modulus of the pressure-sensitive adhesive layer will be described later.

[0071] When the adhesive layer is a single layer, the ultraviolet light (460mJ / cm 2 The tensile modulus at 22° C. after irradiation is preferably 50 MPa to 3000 MPa, more preferably 100 MPa to 1500 MPa, and even more preferably 200 MPa to 1000 MPa. When it is within such a range, a dicing tape having excellent pickup properties can be obtained.

[0072] When the adhesive layer is a single layer, the thickness of the adhesive layer is preferably 5 μm to 470 μm, more preferably 7 μm to 247 μm, and further preferably 10 μm to 130 μm. When it is within such a range, when the adhesive layer is formed on the embossed surface, the adhesive layer fills the embossing well and prevents the generation of useless gaps.

[0073] The total light transmittance of the adhesive layer is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, particularly preferably 95% or more. The total light transmittance of the adhesive layer is, for example, 98% or less, preferably 99% or less.

[0074] The haze value of the pressure-sensitive adhesive layer is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. The haze value of the pressure-sensitive adhesive layer is, for example, 1% or more.

[0075] C-3.2-layer adhesive layer

[0076] In another embodiment, the above-mentioned adhesive layer is made up of 2 layers. Below, for convenience, the adhesive layer on the substrate side is set as the first adhesive layer, and the adhesive layer on the opposite side with the substrate is set as the second adhesive layer. The first adhesive layer and the second adhesive layer can be distinguished by the difference of tensile elastic modulus. The first adhesive layer is preferably lower than the second adhesive layer elasticity. By setting the first adhesive layer of low elasticity as the substrate side, the adhesive layer and the substrate are well fitted, thereby the generation of the space near the interface of the substrate and the adhesive layer can be suppressed. In addition, by possessing the second adhesive layer of high elasticity, thereby can be used as the cutting tape that can contribute to high-precision cutting.

[0077] In this embodiment, the tensile modulus of elasticity at 22°C of the first adhesive layer is preferably 0.05MPa to 1MPa, more preferably 0.06MPa to 0.8MPa, and further preferably 0.07MPa to 0.5MPa. When it is in such a range, the adhesive layer is well adhered to the substrate, thereby significantly suppressing the generation of voids near the interface between the substrate and the adhesive layer. In particular, when a substrate with an embossing treatment applied to the surface of the adhesive layer side is used, voids are usually easily generated. By setting the tensile modulus of elasticity of the adhesive layer to the above range, the generation of voids can be suppressed. It should be noted that when the first adhesive layer is composed of an active energy ray-curable adhesive, the tensile modulus of elasticity at 22°C before irradiation with active energy rays is preferably in this range.

[0078] In one embodiment, the ultraviolet light (460 mJ / cm 2 The tensile modulus at 22° C. after irradiation is preferably 50 MPa to 300 MPa, more preferably 100 MPa to 1500 MPa, and further preferably 200 MPa to 1000 MPa. When it is within such a range, it can be suitably used as a dicing tape having excellent pickup properties.

[0079] The tensile modulus of the second adhesive layer at 22°C is preferably 0.1MPa to 2MPa, more preferably 0.15MPa to 1.5MPa, and further preferably 0.2MPa to 1MPa. When it is in such a range, a dicing tape having moderate rigidity as the adhesive layer as a whole and being helpful for high-precision dicing can be obtained. It should be noted that, when the second adhesive layer is composed of an active energy ray-curable adhesive, the tensile modulus at 22°C before irradiation with active energy rays is preferably within this range.

[0080] The thickness of the first adhesive layer is preferably 5 μm to 468 μm, more preferably 7 μm to 244 μm. When the thickness of the first adhesive layer is 5 μm or more, when the first adhesive layer is formed on the embossed surface, the first adhesive layer fills the embossing well, thereby preventing the generation of useless gaps. In addition, when the first adhesive layer is 468 μm or less, it is easy to pick up the workpiece (for example, semiconductor chip) that has been cut into small pieces when used as a dicing tape.

[0081] The thickness of the second pressure-sensitive adhesive layer is preferably 2 μm to 465 μm, more preferably 3 μm to 240 μm.

[0082] When the pressure-sensitive adhesive layer has a two-layer structure, the total thickness of the pressure-sensitive adhesive layer is preferably 7 μm to 470 μm, more preferably 10 μm to 247 μm, and even more preferably 15 μm to 130 μm.

[0083] When the adhesive layer is a two-layer structure, the total light transmittance of the adhesive layer is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. The total light transmittance of the adhesive layer is, for example, 98% or less, preferably 99% or less.

[0084] When the pressure-sensitive adhesive layer has a two-layer structure, the haze value of the pressure-sensitive adhesive layer is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. The haze value of the pressure-sensitive adhesive layer is, for example, 1% or more.

[0085] As the adhesive constituting the first adhesive layer and the second adhesive layer, the adhesive described in the above section C-1 can be used, and an active energy ray-curable adhesive is preferably used.

[0086] The crosslinking agent content of the active energy ray-curable adhesive constituting the first adhesive layer is preferably 0.005 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, relative to 100 parts by weight of the base polymer of the adhesive. Within such a range, an adhesive layer can be formed that appropriately adjusts the elastic modulus, well fills the embossed surface of the substrate, and can maintain a fixed shape.

[0087] The crosslinking agent content of the active energy ray-curable adhesive constituting the second adhesive layer is preferably 1 to 20 parts by weight, more preferably 2 to 10 parts by weight relative to 100 parts by weight of the base polymer of the adhesive. When it is within such a range, an adhesive layer with appropriately adjusted elastic modulus and adhesive strength (which can take into account both the retention of the wafer during dicing and the adhesive strength for chip pickup after dicing) can be formed.

[0088] D. Manufacturing method of cutting tape

[0089] The above-mentioned dicing tape can be manufactured by any appropriate method. For example, the dicing tape can be obtained by coating the above-mentioned adhesive on a substrate. As the coating method, various methods such as rod coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. can be adopted. In addition, a method of forming an adhesive layer on a separator separately and then laminating it to a substrate can also be adopted.

[0090] [Example]

[0091] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples. The test and evaluation methods in the examples are as follows. In addition, "parts" and "%" are by weight unless otherwise specified.

[0092] <Production Example 1> Preparation of polymer solution

[0093] 100 parts by weight of 2-methoxyethyl acrylate, 27 parts by weight of acryloylmorpholine, and 22 parts by weight of 2-hydroxyethyl acrylate were mixed to prepare a monomer solution 1. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirrer, and 500 parts by weight of ethyl acetate, the monomer solution 1, and 0.2 parts by weight of azobisisobutyronitrile (AIBN) were added under a nitrogen atmosphere, and stirred at 60°C for 24 hours. Thereafter, the mixture was cooled to room temperature to obtain an acrylic copolymer solution containing an acrylic copolymer (weight average molecular weight: 600,000). 24 parts by weight of 2-methacryloyloxyethyl isocyanate was added to the obtained acrylic copolymer solution to react, and an acrylic copolymer solution 1 (polymer) having a weight average molecular weight of 800,000 in which the side chain terminal OH of 2-hydroxyethyl acrylate in the copolymer was added to an NCO group and a carbon-carbon double bond was provided at the terminal.

[0094] [Examples 1 to 6]

[0095] (Preparation of First Adhesive Layer Forming Composition)

[0096] 0.025 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, trade name: CORONATE L), 7 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name: Irgacure 184), and a diluent (ethyl acetate) were mixed with 100 parts by weight of the acrylic polymer solution obtained in Production Example 1 and stirred to obtain a pressure-sensitive adhesive composition.

[0097] (Preparation of Second Adhesive Layer Forming Composition)

[0098] 7 parts by weight of a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., trade name: Irgacure 184), 7 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, trade name: CORONATE L) and additives in the amounts described in Table 1, and a diluting solvent (ethyl acetate) were mixed with 100 parts by weight of the acrylic polymer solution obtained in Production Example 1 and stirred to obtain an adhesive composition.

[0099] (Making of base material)

[0100] High-pressure polyethylene (PE) (manufactured by Sumitomo Chemical Co., Ltd., trade name: SUMIKATHENE F213-P) was put into an extruder and subjected to T-die melt co-extrusion (extruder: manufactured by GM ENGINEERING co., Ltd., trade name: GM30-28 / T die: feed block method; extrusion temperature 240°C), and then, a single side of the film was subjected to embossing treatment with a surface roughness Ra: 1.42 μm to obtain a film with a thickness of 100 μm. It should be noted that the thickness of the layer is controlled by the shape of the T-die outlet. The embossed surface of the obtained film was subjected to corona treatment. It should be noted that the surface roughness Ra of the embossed surface was measured by KEYENCE CORPORATION, trade name: VK-X150.

[0101] (Production of Isolator)

[0102] As the separator, a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Plastics Corporation, trade name: MRF38, thickness: 38 μm) having one surface treated with silicone was used.

[0103] (Production of cutting tape)

[0104] The first adhesive layer-forming composition was applied to the silicone-treated surface of the separator, and then heated at 120° C. for 2 minutes to form a first adhesive layer having a thickness of 10 μm.

[0105] Separately, a second adhesive layer-forming composition was applied to the silicone-treated surface of the separator, and then heated at 120° C. for 2 minutes to form an adhesive layer having a thickness described in Table 1.

[0106] The first adhesive layer was transferred to the substrate using a hand roller, and the second adhesive layer was further transferred to the first adhesive layer, followed by aging treatment at 50° C. for 48 hours to obtain a dicing tape. The adhesive layer was laminated on the embossed surface of the substrate.

[0107] (Comparative Examples 1 to 7)

[0108] A dicing tape was obtained in the same manner as in Example except that the additives described in Table 1 and the crosslinking agent and the additives were used in the contents described in Table 1.

[0109] The following evaluations were performed using the dicing tapes obtained in Examples and Comparative Examples.

[0110] (1) Determination of isopropanol extract

[0111] A SUS ring with an inner diameter of 75 mm (inner diameter: 44.2 cm 2 ) is attached to the adhesive layer of the dicing tape, 4 ml of isopropyl alcohol is added to the inner side of the SUS ring and allowed to stand for 30 minutes. Thereafter, the isopropyl alcohol is recovered to a glass bottle whose weight has been measured in advance. Next, the glass bottle is heated at 130°C for 3 hours, dried at 180°C for 1 hour, and the weight of the glass bottle is measured. The value obtained by subtracting the weight of the heated glass bottle from the weight of the glass bottle before heating (before isopropyl alcohol is recovered) is taken as the weight of the eluted substance.

[0112] (2) Height difference tracking performance (bump filling performance)

[0113] A back grinding tape bonding machine (manufactured by Nitto Seiki Co., Ltd., product name: R-3000III) was used to bond the dicing tape to a semiconductor wafer (a 4-inch silicon mirror wafer with bumps of 5 μm height / 30 μm spacing) at a conveying speed of 10 mm / sec and a pressure of 0.20 MPa during bonding. After bonding, the semiconductor wafer with the dicing tape was placed in an environment of 22°C, and the height difference tracking performance was evaluated by using an optical microscope (250 times) to determine whether the dicing tape was bonded to the gap between the bumps. In Table 1, the case where the dicing tape was bonded to the gap was marked as ○, and the case where it was not bonded was marked as ×.

[0114] [Table 1]

[0115]

[0116] As is clear from Table 1, the dicing tapes of Examples 1 to 6 have a small amount of isopropyl alcohol elution and can prevent contamination of the wafer. In addition, they are excellent in embedding properties and can be suitably used for adherends having an uneven surface.

Claims

1. A dicing tape comprising: a substrate, and an adhesive layer disposed on one side of the substrate, The dicing tape is used in a method for manufacturing a semiconductor wafer including a solvent cleaning process. The isopropyl alcohol eluate of the adhesive layer is 5 mg or less. The adhesive layer has a two-layer structure, the adhesive layer on the substrate side is the first adhesive layer, and the adhesive layer on the opposite side to the substrate is the second adhesive layer, and the second adhesive layer contains an additive with a weight average molecular weight of 5000 or more. The first adhesive layer and the second adhesive layer have different tensile elastic moduli. The first adhesive layer has a tensile elastic modulus at 22° C. of 0.05 MPa to 1 MPa.

2. The cutting tape according to claim 1, wherein: The composition forming the adhesive layer includes an additive having a weight average molecular weight of 5,000 or more.

3. The cutting tape according to claim 2, wherein: The content of the additive is 5 to 100 parts by weight based on 100 parts by weight of the base polymer of the composition forming the adhesive layer. 4 . The dicing tape according to claim 1 , which is used by being bonded to an adherend having an uneven surface.

5. The cutting tape according to claim 4, wherein: The adherend with the concavo-convex surface is a TSV wafer.

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