JP7324023B2 - dicing tape - Google Patents

Description

The present invention relates to a dicing tape.

A workpiece (for example, a semiconductor wafer) that is an assembly of electronic components is manufactured with a large diameter, and after forming a pattern on the surface, the back surface is usually ground so that the thickness of the wafer is about 100 μm to 600 μm. It is cut and separated (diced) into element pieces, and further transferred to the mounting process. In this dicing process, the work is cut into small pieces. In the process of manufacturing semiconductors, adhesive sheets are used to fix semiconductor wafers and dicing frames (eg, SUS rings) used in the dicing process (eg, Patent Document 1).

As the semiconductor wafer is processed to be thin by the back grinding process, its strength is lowered, and the wafer may crack and/or warp. Furthermore, wafers with reduced strength are difficult to handle. Therefore, in some cases, support material such as glass or hard plastic is attached to the wafer in advance and the back grinding process is performed to ensure the strength of the wafer. This support material is attached to the wafer using, for example, an adhesive composition or an adhesive tape. This support material can support the wafer during backgrinding and backside wiring and bump formation steps. After that, the wafer is attached to an adhesive sheet (for example, a dicing tape), and after the support material is peeled off, the wafer is subjected to a dicing process. Therefore, as an adhesive for adhering the support material, an adhesive that can be easily peeled off after the back grinding process has been proposed (for example, Patent Document 1). In general, when the support material is attached using an adhesive, the support material is peeled off by dissolving the adhesive using a solvent. However, there is a problem that the adhesive force of the adhesive tape (dicing tape) is lowered in the cleaning process (dissolving the adhesive) with a solvent, and the wafer cannot be sufficiently held. In addition, there is also the problem that the adhesive dissolved in the solvent causes contamination of the wafer, resulting in a decrease in yield.

JP 2003-007646 A JP 2014-37458 A

The present invention has been made to solve the above-mentioned conventional problems, and even when used in the manufacture of semiconductor wafers including a solvent cleaning process, the wafer can be properly held and the wafer contamination caused by the adhesive can be prevented. To provide a dicing tape capable of preventing a decrease in yield.

The dicing tape of the present invention comprises a substrate and an adhesive layer disposed on one side of the substrate, and is used in a method for manufacturing semiconductor wafers including a solvent cleaning step. The amount of isopropyl alcohol extractables from this pressure-sensitive adhesive layer is 5 mg or less.
In one embodiment, the composition forming the pressure-sensitive adhesive layer contains an additive having a weight average molecular weight of 5000 or more.
In one embodiment, the content of the additive is 5 to 100 parts by weight with respect to 100 parts by weight of the base polymer of the adhesive.
In one embodiment, the dicing tape of the present invention is used by bonding it to an adherend having an uneven surface.
In one embodiment, the adherend having the uneven surface is a TSV wafer.

The dicing tape of the present invention comprises a substrate and an adhesive layer disposed on one side of the substrate, and the isopropyl alcohol eluate of the adhesive layer is 5 mg or less. By using such a dicing tape, even when it is used in the manufacture of semiconductor wafers including a solvent cleaning process, the dicing tape can properly hold the wafer and prevent a decrease in yield due to wafer contamination of the adhesive. can be provided.

1 is a schematic cross-sectional view of a dicing tape according to one embodiment of the invention; FIG.

A. Overview of Dicing Tape FIG. 1 is a schematic cross-sectional view of a dicing tape according to one embodiment of the present invention. The illustrated dicing tape 100 includes a substrate 10 and an adhesive layer 20 disposed on one surface of the substrate 10 . The pressure-sensitive adhesive layer is typically formed from an active energy ray-curable pressure-sensitive adhesive composition. Practically, a separator is temporarily releasably adhered to the adhesive layer 20 in order to appropriately protect the adhesive layer 20 until use. Dicing tape 100 may also include any other appropriate layers. Preferably, the adhesive layer is placed directly on the substrate.

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

The dicing tape of the present invention is used in a method for manufacturing semiconductor wafers including a solvent cleaning step. In the solvent washing step, washing with a hydrophobic organic solvent (e.g., d-limonene) to remove the adhesive used to attach the support material, and hydrophilic solvent (e.g., , isopropyl alcohol). The amount of isopropyl alcohol eluate in the adhesive layer 20 is 5 mg or less, preferably 4 mg or less, and more preferably 3 mg or less. Since the amount of isopropyl alcohol eluted in the adhesive layer is 5 mg or less, the wafer can be properly held even when used in the production of semiconductor wafers including a solvent cleaning process, and the yield is reduced due to wafer contamination of the adhesive. can prevent The amount of isopropyl alcohol eluate in the pressure-sensitive adhesive layer is preferably as small as possible, and may be, for example, 0 mg. In this specification, the isopropyl alcohol eluate of the pressure-sensitive 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 adhered to the adhesive layer of the dicing tape, 4 ml of isopropyl alcohol is added to the inside of the SUS ring, and left to stand for 30 minutes. The isopropyl alcohol is then collected in a pre-weighed glass bottle. 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 weight of the eluate (mg) was obtained by subtracting the weight of the glass bottle after heating from the weight of the glass bottle before heating (before recovery of isopropyl alcohol).

The initial adhesive force at 23° C. when the dicing tape of the present invention is attached to a stainless steel plate is preferably 0.2 N/20 mm to 10 N/20 mm, more preferably 0.5 N/20 mm to 6 N/20 mm. . As used herein, adhesive strength refers to a value measured according to JIS Z 0237:2000. Specifically, the dicing tape was attached to a stainless steel plate (arithmetic mean surface roughness Ra: 50 ± 25 nm) by reciprocating a 2 kg roller once, left at 23 ° C. for 30 minutes, and then peeled at a peel angle of 180 °. A value measured by peeling off the dicing tape at a speed (pulling speed) of 300 mm/min. As used herein, "initial adhesive strength" means adhesive strength before irradiation with active energy rays.

In one embodiment, the dicing tape is attached to a silicon mirror wafer, and the adhesive force at 23° C. after irradiation with 460 mJ/cm ² ultraviolet rays is preferably 0.01 N/20 mm to 0.3 N/20 mm. and more preferably 0.02 N/20 mm to 0.2 N/20 mm. Within this range, a dicing tape can be obtained in which the adhesive strength is reduced by UV irradiation after dicing, making it easy to pick up small pieces of workpieces (eg, semiconductor chips). The above ultraviolet irradiation is performed, for example, by using an ultraviolet irradiation device (Nitto Seiki Co., Ltd., trade name “UM-810”) and applying ultraviolet rays from a high-pressure mercury lamp (characteristic wavelength: 365 nm, integrated light amount: 460 mJ/cm ² , irradiation energy: 70 W. /cm ² ) to the adhesive layer for 6.6 seconds.

The thickness of the dicing tape is preferably 35 μm to 500 μm, more preferably 60 μm to 300 μm, still more preferably 80 μm to 200 μm.

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

In the dicing tape, the transmittance of light having a wavelength of 1064 nm is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. Within such a range, it can be suitably used in a semiconductor wafer manufacturing process including a stealth dicing process. The transmittance of light with a wavelength of 1064 nm of the dicing tape is, for example, 98% or less, preferably 99% or less.

The haze value of the dicing tape is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. Within such a range, it can be suitably used in a semiconductor wafer manufacturing process including a stealth dicing process. The haze value of the dicing tape is, for example, 1% or more.

B. Substrate The substrate 10 may be made of any appropriate resin. Examples of the resin include polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, polybutene-based resins, and polymethylpentene-based resins, polyurethane-based resins, polyester-based resins, polyimide-based resins, polyetherketone-based resins, and polystyrene-based resins. Resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicon resins, cellulose resins, ionomer resins, and the like can be mentioned. Polyolefin resins are preferred.

In one embodiment, the substrate contains a polyethylene-based resin. Examples of polyethylene-based resins include low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, and ultra-low-density polyethylene.

The content of ethylene-derived structural units in the polyethylene resin is preferably 80 mol % or more, more preferably 90 mol % or more, and still more preferably 95 mol % or more. Structural units other than ethylene-derived structural units include structural units derived from monomers copolymerizable with ethylene and copolymers, such as propylene, 1-butene, isobutene, 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-icosene and the like.

The content of the polyethylene resin is preferably 80% by weight or more, more preferably 85% to 100% by weight, still more preferably 95% to 100% by weight, of the resin forming the base material.

The substrate may further contain any suitable additive. Examples of additives include lubricants, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, colorants and the like.

In one embodiment, one surface of the substrate is preferably embossed. Preferably, only one side of the base material is embossed, and the embossed side is the pressure-sensitive adhesive layer side. By embossing the adhesive layer side surface, the adhesiveness between the adhesive layer and the substrate can be improved. The arithmetic mean surface roughness Ra (JIS B 0601) of the non-embossed surface of the substrate is preferably less than 1.0 μm, more preferably 0.8 μm or less, still more preferably 0.5 μm or less, Especially preferred is 0.01 μm to 0.5 μm. The arithmetic mean surface roughness Ra (JIS B 0601) 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 base material exceeds 3 μm, there is a risk that gaps are likely to form between the pressure-sensitive adhesive layer and the base material. Also, if the Ra is less than 1 μm, blocking may occur during storage of the substrate.

The thickness of the substrate is preferably 30 μm to 300 μm, more preferably 53 μm to 200 μm, still more preferably 70 μm to 160 μm.

The total light transmittance of the substrate is preferably 70% or higher, more preferably 80% or higher, even more preferably 90% or higher, and particularly preferably 95% or higher. The total light transmittance of the substrate is preferably 98% or less, more preferably 99% or less.

The tensile modulus of elasticity at 22° C. of the substrate is preferably 50 MPa to 120 MPa, more preferably 70 MPa to 90 MPa. Within such a range, a dicing tape with excellent expandability can be obtained. The tensile modulus of elasticity of the substrate is measured using a tensile tester (manufactured by SHIMADZU, "AG-IS") under the conditions of distance between chucks: 50 mm, tensile speed: 300 mm/min, and substrate width: 10 mm. .

C. Adhesive Layer The adhesive layer 20 is formed using a composition that forms an adhesive layer (adhesive composition). As described above, the isopropyl alcohol eluate of the pressure-sensitive adhesive layer is 5 mg or less. Since the amount of isopropyl alcohol eluted in the adhesive layer is 5 mg or less, the wafer can be properly held even when used in a semiconductor wafer manufacturing process including a solvent cleaning process, and the yield is reduced due to wafer contamination of the adhesive. A dicing tape that can prevent deterioration can be provided.

C-1. Adhesive composition Any appropriate adhesive is used as the adhesive layer composition (adhesive). For example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyvinyl ether-based pressure-sensitive adhesives, and the like can be mentioned.

In one embodiment, the pressure-sensitive adhesive composition is preferably an active energy ray-curable pressure-sensitive adhesive composition. By using an active energy ray-curable adhesive, the adhesive strength is reduced by irradiation with active energy rays (typically, ultraviolet rays) after dicing, making it easier to pick up small pieces of workpieces (e.g., semiconductor chips). A dicing tape that can be obtained can be obtained.

C-1-1. Base Polymer The adhesive composition may comprise a base polymer that exhibits tackiness. Monomers constituting the base polymer include, for example, hydrophilic monomers. Any suitable monomer having a polar group can be used as the hydrophilic monomer. Specifically, carboxyl group-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 isotanoic anhydride. ; 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, (4-hydroxymethylcyclohexyl) hydroxyl group-containing monomers such as methyl methacrylate; styrenesulfonic acid, allylsulfonic acid, 2-(meth) Sulfonic acid group-containing monomers such as acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid; phosphoric acid such as 2-hydroxyethyl acryloyl phosphate Group-containing monomer; (N -Substituted) amide-based monomers; (meth)aminoalkyl acrylate-based monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; Alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide Monomer; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide ; succinimide-based monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; vinyl acetate, vinyl propionate , N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene , Vinyl monomers such as N-vinylcaprolactam; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; Polyethylene glycol (meth)acrylate, (meth)acrylic acid glycol-based acrylic ester monomers such as polypropylene glycol, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicon (meth)acrylate, etc. Heterocyclic ring, halogen atom, acrylate monomer having silicon atom, etc.; 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, urethane acrylate, etc. Polyfunctional monomers can be mentioned. Hydroxyl group-containing monomers and/or (N-substituted) amide monomers can be suitably used as hydrophilic monomers. Only one type of hydrophilic monomer may be used, or two or more types may be used in combination.

Also, the hydrophilic monomer and the hydrophobic monomer may be used in combination. As the hydrophobic monomer, any appropriate monomer can be used as long as it is a monomer having hydrophobic properties. Specifically, vinyl alkyl or aryl ether having an alkyl group having 9 to 30 carbon atoms such as vinyl 2-ethylhexanoate, vinyl laurate, vinyl stearate, stearyl vinyl ether; hexyl (meth)acrylate, (meth)acrylate heptyl 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 (meth)acrylic acid having 6 to 30 carbon atoms; fatty acid and unsaturated vinyl esters of (meth)acrylic acid derived from fatty alcohols; monomers derived from cholesterol; 1-butene, 2-butene, 1-pentene, 1-hexene, 1-octene, isobutylene, isoprene, etc. of olefin monomers. Only one type of hydrophobic monomer may be used, or two or more types may be used in combination. 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.

The base polymer may further contain 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.

The base polymer may further contain a structural unit derived from an isocyanate compound having a curable functional group in the molecule. A base polymer containing a structural unit derived from an isocyanate compound can be obtained, for example, by reacting a substituent (e.g., OH group) of the structural unit derived from the hydrophilic monomer with an NCO group of the isocyanate compound. Examples of the isocyanate compounds include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate and the like.

The weight average molecular weight of the base polymer constituting the pressure-sensitive adhesive is preferably 300,000 to 2,000,000, more preferably 500,000 to 1,500,000. A weight average molecular weight can be measured by GPC (solvent: THF).

C-1-2. Additive with Weight Average Molecular Weight of 5000 or More The adhesive composition preferably contains an additive with a weight average molecular weight of 5000 or more. By containing such an additive, the amount of isopropyl alcohol eluate in the pressure-sensitive adhesive layer can be reduced. Moreover, even when the adherend has an uneven surface (for example, a TSV wafer), the pressure-sensitive adhesive layer adheres even to the concave portions, and the adherend can be sufficiently held. The weight average molecular weight of the additive is preferably 7,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more. Also, the weight average molecular weight of the additive is preferably 70,000 or less, more preferably 50,000 or less. The weight average molecular weight of the additive can be measured, for example, by GPC (solvent: THF).

Any suitable polymer or oligomer, for example, can be used as the additive having a weight average molecular weight of 5000 or more. Specific examples include active energy ray-reactive oligomers and thermosetting oligomers. Active energy ray-reactive oligomers are preferred. Only one such additive may be used, or two or more thereof may be used in combination.

Examples of active energy ray-reactive oligomers include urethane acrylate-based oligomers, epoxy (meth)acrylate-based oligomers, acrylic (meth)acrylate-based oligomers, and the like. Urethane acrylate-based oligomers, acrylic (meth)acrylate-based oligomers, and the like are preferably used.

A commercially available product may be used as the active energy ray-reactive oligomer. Examples thereof include Shiko (registered trademark) UV-3000B (weight average molecular weight: 18000) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Aronix M321 (weight average molecular weight: 10000) manufactured by Toagosei Co., Ltd., and the like.

Any appropriate oligomer having at least one thermosetting functional group such as a glycidyl group, a carboxyl group, a hydroxyl group, an amino group, or the like can be used as the thermosetting oligomer.

As described above, in one embodiment of the invention, the pressure-sensitive adhesive layer has a two-layer structure. In the case of a dicing tape having such a two-layered pressure-sensitive adhesive layer, at least the second pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer in contact with the adherend) contains an additive having a weight average molecular weight of 5000 or more. good.

C-1-3. Polymerization Initiator The active energy ray-curable pressure-sensitive adhesive composition typically contains a polymerization initiator. Any appropriate initiator can be used as the polymerization initiator, and a photopolymerization initiator is preferably used. Any appropriate initiator can be used as the photopolymerization initiator. Examples of photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropio α-ketol compounds such as phenone and 1-hydroxycyclohexylphenyl ketone; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio) Acetophenone compounds such as -phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; ketal compounds such as benzyl dimethyl ketal; 2-naphthalenesulfonyl chloride, etc. aromatic sulfonyl chloride compounds; 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl) oxime and other photoactive oxime compounds; benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4 -benzophenone compounds such as methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4 thioxanthone-based compounds such as diethylthioxanthone and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; A photoinitiator may use only 1 type and may be used in combination of 2 or more type. The amount of photopolymerization initiator used can 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, per 100 parts by weight of the base polymer.

A commercially available product may be used as the photopolymerization initiator. For example, trade names such as "Irgacure 651", "Irgacure 184", "Irgacure 369", "Irgacure 819" and "Irgacure 2959" manufactured by BASF are listed.

C-1-4. Crosslinking Agent The active energy ray-curable pressure-sensitive adhesive composition preferably further contains a crosslinking agent. Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, Examples include metal chelate cross-linking agents, metal salt cross-linking agents, carbodiimide cross-linking agents, amine cross-linking agents and the like.

In one embodiment, an isocyanate-based cross-linking agent is preferably used. An isocyanate-based cross-linking agent is preferable because it can react with various functional groups. Specific examples of the isocyanate-based cross-linking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; Aromatic isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / Isocyanate adducts such as hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"), etc. things; and the like. Preferably, a cross-linking agent having 3 or more isocyanate groups is used.

The active energy ray-curable pressure-sensitive adhesive composition may further contain any appropriate additive. Additives include, for example, active energy ray polymerization accelerators, radical scavengers, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers), pigments, dyes, fillers. , antioxidants, conductive agents, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

The content of the cross-linking agent can be adjusted to any suitable amount. For example, it is 0.005 to 20 parts by weight, preferably 0.02 to 10 parts by weight, per 100 parts by weight of the base polymer. In addition, when the pressure-sensitive adhesive layer has a single-layer structure, the content of the cross-linking agent is preferably 0.1 to 10 parts by weight, more preferably 0, with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive. .5 to 8 parts by weight. Within such a range, a pressure-sensitive adhesive layer having an appropriately adjusted elastic modulus can be formed.

C-2. Adhesive Layer Constructed of Single Layer In one embodiment, the adhesive layer is composed of a single layer. When the adhesive layer has a single-layer structure, the tensile modulus of the adhesive layer at 22° C. is preferably 0.05 MPa to 1 MPa, more preferably 0.1 MPa to 0.8 MPa, and still more preferably 0. 0.15 MPa to 0.6 MPa. Within such a range, a pressure-sensitive adhesive layer having sufficient strength can be formed, and the pressure-sensitive adhesive layer and the substrate are well adhered to each other, and voids are generated in the vicinity of the interface between the substrate and the pressure-sensitive adhesive layer. can be suppressed. In particular, when using a substrate having an embossed surface on the pressure-sensitive adhesive layer side, voids are likely to occur normally. By setting the tensile modulus of elasticity of the pressure-sensitive adhesive layer within the above range, the generation of voids can be suppressed. If the tensile modulus exceeds 1 MPa, the adhesive layer may not conform to the unevenness of the substrate when the adhesive layer is laminated on the embossed surface of the substrate. On the other hand, if the tensile modulus is less than 0.05 MPa, the pressure-sensitive adhesive layer may not maintain a fixed shape and may not have sufficient properties. As described above, when the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, it is preferable that the tensile modulus at 22° C. before irradiation with the active energy ray is within the above range. A method for measuring the tensile modulus of the pressure-sensitive adhesive layer will be described later.

When the pressure-sensitive adhesive layer has a single layer structure, the tensile modulus of elasticity at 22° C. of the pressure-sensitive adhesive layer after irradiation with ultraviolet rays (460 mJ/cm ² ) is preferably 50 MPa to 3000 MPa, more preferably 100 MPa to 1500 MPa, and further. It is preferably 200 MPa to 1000 MPa. Within such a range, a dicing tape with excellent pick-up properties can be obtained.

When the pressure-sensitive adhesive layer has a single layer structure, the thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 470 μm, more preferably 7 μm to 247 μm, still more preferably 10 μm to 130 μm. Within such a range, when the pressure-sensitive adhesive layer is formed on the embossed surface, the pressure-sensitive adhesive layer satisfactorily fills the embossments, and the generation of unnecessary voids can be prevented.

The total light transmittance of the adhesive layer is preferably 70% or higher, more preferably 80% or higher, still more preferably 90% or higher, and particularly preferably 95% or higher. The total light transmittance of the adhesive layer is, for example, 98% or less, preferably 99% or less.

The haze value of the adhesive layer is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. The haze value of the adhesive layer is, for example, 1% or more.

C-3. Adhesive Layer Constructed of Two Layers In another embodiment, the adhesive layer is composed of two layers. Hereinafter, for the sake of convenience, the pressure-sensitive adhesive layer on the substrate side is referred to as the first pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer on the side opposite to the substrate is referred to as the second pressure-sensitive adhesive layer. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer can be distinguished by a difference in tensile elastic modulus. The first adhesive layer preferably has lower elasticity than the second adhesive layer. By placing the first pressure-sensitive adhesive layer with low elasticity on the side of the substrate, the pressure-sensitive adhesive layer and the substrate are well adhered to suppress the generation of voids near the interface between the substrate and the pressure-sensitive adhesive layer. be able to. In addition, by providing the highly elastic second pressure-sensitive adhesive layer, it can be used as a dicing tape that can contribute to highly accurate dicing.

In this embodiment, the tensile elastic modulus of the first pressure-sensitive adhesive layer at 22° C. is preferably 0.05 MPa to 1 MPa, more preferably 0.06 MPa to 0.8 MPa, still more preferably 0.07 MPa to 0.5 MPa. Within such a range, the pressure-sensitive adhesive layer and the substrate adhere well, and the generation of voids in the vicinity of the interface between the substrate and the pressure-sensitive adhesive layer can be significantly suppressed. In particular, when using a substrate having an embossed surface on the pressure-sensitive adhesive layer side, voids are likely to occur normally. By setting the tensile modulus of elasticity of the pressure-sensitive adhesive layer within the above range, the generation of voids can be suppressed. In addition, when the first pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, it is preferable that the tensile elastic modulus at 22° C. before the irradiation of the active energy ray is within the above range.

In one embodiment, the tensile elastic modulus at 22° C. of the first pressure-sensitive adhesive layer after irradiation with ultraviolet rays (460 mJ/cm ² ) is preferably 50 MPa to 300 MPa, more preferably 100 MPa to 1500 MPa, and further It is preferably 200 MPa to 1000 MPa. Within such a range, it can be suitably used as a dicing tape with excellent pick-up properties.

The tensile elastic modulus of the second pressure-sensitive adhesive layer at 22° C. is preferably 0.1 MPa to 2 MPa, more preferably 0.15 MPa to 1.5 MPa, still more preferably 0.2 MPa to 1 MPa. Within such a range, it is possible to obtain a dicing tape that has appropriate rigidity as a whole pressure-sensitive adhesive layer and that can contribute to highly accurate dicing. In addition, when the second pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, it is preferable that the tensile elastic modulus at 22° C. before the irradiation of the active energy ray is within the above range.

The thickness of the first adhesive layer is preferably 5 μm to 468 μm, more preferably 7 μm to 244 μm. If the thickness of the first pressure-sensitive adhesive layer is 5 μm or more, when the first pressure-sensitive adhesive layer is formed on the embossed surface, the first pressure-sensitive adhesive layer satisfactorily fills the embossments, creating unnecessary voids. can be prevented. Also, if the first pressure-sensitive adhesive layer is 468 μm or less, it is possible to easily pick up a piece of work (for example, a semiconductor chip) when using it as a dicing tape.

The thickness of the second adhesive layer is preferably 2 μm to 465 μm, more preferably 3 μm to 240 μm.

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, still more preferably 15 μm to 130 μm.

When the pressure-sensitive adhesive layer has a two-layer structure, the total light transmittance of the pressure-sensitive adhesive layer is preferably 70% or more, more preferably 80% or more, still more 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.

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 adhesive layer is, for example, 1% or more.

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. Preferably, an active energy ray-curable adhesive is used.

The cross-linking agent content of the active energy ray-curable adhesive constituting the first adhesive layer is preferably 0.005 parts by weight to 5 parts by weight with respect to 100 parts by weight of the base polymer of the adhesive, and more It is preferably 0.02 to 3 parts by weight. Within such a range, the elastic modulus is appropriately adjusted, the embossed surface of the base material is satisfactorily filled, and a pressure-sensitive adhesive layer capable of maintaining a regular shape can be formed.

The content of the cross-linking agent in the active energy ray-curable pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer is preferably 1 to 20 parts by weight, more preferably 100 parts by weight of the base polymer of the pressure-sensitive adhesive. 2 to 10 parts by weight. Within such a range, it is possible to form a pressure-sensitive adhesive layer in which the elastic modulus and adhesive strength (adhesive strength that enables both wafer holding during dicing and chip pick-up after dicing) are appropriately adjusted. .

D. Manufacturing Method of Dicing Tape The dicing tape can be manufactured by any appropriate method. A dicing tape can be obtained, for example, by applying the pressure-sensitive adhesive onto a substrate. Coating methods include bar coater 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. Various methods can be employed. Alternatively, a method of separately forming an adhesive layer on a separator and then attaching it to a substrate may be adopted.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Tests and evaluation methods in Examples are as follows. Also, "parts" and "%" are by weight unless otherwise specified.

<Production Example 1> Preparation of Polymer Solution Monomer solution 1 was prepared by mixing 100 parts by weight of 2-methoxyethyl acrylate, 27 parts by weight of acryloylmorpholine and 22 parts by weight of 2-hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 500 parts by weight of ethyl acetate, monomer liquid 1, and 0.2 parts by weight of azoisobutylnitrile (AIBN). was charged and stirred at 60° C. for 24 hours. Then, it 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 and reacted to add an NCO group to the side chain terminal OH group of 2-hydroxyethyl acrylate in the copolymer. , an acrylic copolymer solution 1 (polymer) having a weight-average molecular weight of 800,000 and having carbon-carbon double bonds at the terminals was obtained.

[Examples 1 to 6]
(Preparation of first pressure-sensitive adhesive layer-forming composition)
To 100 parts by weight of the acrylic polymer solution obtained in Production Example 1, 0.025 parts by weight of a cross-linking agent (manufactured by Tosoh Corporation, trade name: Coronate L), a photopolymerization initiator (manufactured by BASF, trade name: Irgacure 184). 7 parts by weight and a dilution solvent (ethyl acetate) were blended and stirred to obtain an adhesive composition.
(Preparation of second pressure-sensitive adhesive layer-forming composition)
To 100 parts by weight of the acrylic polymer solution obtained in Production Example 1, 7 parts by weight of a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., trade name: Irgacure 184), and the amount of crosslinking agent (Tosoh Corporation) added in Table 1 Company, trade name: Coronate L), an additive, and a dilution solvent (ethyl acetate) were blended and stirred to obtain an adhesive composition.
(Preparation of base material)
High-pressure polyethylene (PE) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikasen F213-P) is put into an extruder, and T-die melt co-extrusion (extruder: manufactured by GM Engineering, trade name: GM30- 28/T die: feed block method; extrusion temperature: 240° C.), and then, one side of the film was embossed with a surface roughness Ra of 1.42 μm to obtain a film with a thickness of 100 μm. The thickness of the layer was controlled by the shape of the T-die exit. The embossed surface of the obtained film was subjected to corona treatment. The surface roughness Ra of the embossed surface was measured with VK-X150 (trade name) manufactured by Keyence Corporation.
(Production of separator)
A polyethylene terephthalate (PET) film (manufactured by Mitsubishi Plastics, trade name: MRF38, thickness: 38 μm) having one surface treated with silicone was used as a separator.
(Preparation of dicing tape)
The silicone-treated surface of the separator was coated with the first pressure-sensitive adhesive layer-forming composition and then heated at 120° C. for 2 minutes to form a first pressure-sensitive adhesive layer having a thickness of 10 μm.
Separately, the silicone-treated surface of the separator was coated with the second pressure-sensitive adhesive layer-forming composition and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer having the thickness shown in Table 1.
Using a hand roller, transfer the first adhesive layer to the base material, further transfer the second adhesive layer to the first adhesive layer, and then perform aging treatment at 50 ° C. for 48 hours to form a dicing tape. got The adhesive layer was laminated on the embossed surface of the substrate.

(Comparative Examples 1 to 7)
A dicing tape was obtained in the same manner as in Examples except that the additive shown in Table 1 was used and the content of the cross-linking agent and additive shown in Table 1 was used.

The following evaluations were performed using the dicing tapes obtained in Examples and Comparative Examples. Table 1 shows the results.

(1) Measurement of isopropyl alcohol eluate A SUS ring with an inner diameter of 75 mm (inner diameter: 44.2 cm ² ) was attached to the adhesive layer of the dicing tape, 4 ml of isopropyl alcohol was added to the inside of the SUS ring, and the mixture was allowed to stand for 30 minutes. . The isopropyl alcohol was then collected in a pre-weighed glass bottle. Then, the glass bottle was heated at 130° C. for 3 hours and dried at 180° C. for 1 hour, and the weight of the glass bottle was measured. The weight of the eluate was obtained by subtracting the weight of the glass bottle after heating from the weight of the glass bottle before heating (before recovery of isopropyl alcohol).

(2) Step followability (bump embedding)
Using a back grind tape applicator (manufactured by Nitto Seiki Co., Ltd., product name: R-3000III), a semiconductor wafer (height 5 μm A dicing tape was attached to a 4-inch silicon mirror wafer on which bumps were formed at intervals of 30 μm. After sticking, the semiconductor wafer with the dicing tape is placed in an environment of 22°C, and an optical microscope (250x magnification) is used to evaluate step followability by whether or not the dicing tape is stuck in the space between the bumps. bottom. In Table 1, ◯ means that the dicing tape is attached to the space, and x means that it is not attached.

As is clear from Table 1, the dicing tapes of Examples 1 to 6 contained a small amount of isopropyl alcohol eluate, and were able to prevent contamination of the wafer. In addition, the embedding property was also excellent, and it could be suitably used for an adherend having an uneven surface.

REFERENCE SIGNS LIST 10 base material 20 adhesive layer 100 dicing tape

Claims (4)

comprising a substrate and an adhesive layer disposed on one side of the substrate;
A dicing tape used in a semiconductor wafer manufacturing method including a solvent cleaning step,
The pressure-sensitive adhesive layer has a two-layer structure, and the pressure-sensitive adhesive layer on the side of the two pressure-sensitive adhesive layers in contact with the adherend contains an additive having a weight average molecular weight of 5000 or more,
A dicing tape, wherein the pressure-sensitive adhesive layer contains 5 mg or less of isopropyl alcohol. 2. The dicing tape according to claim 1, wherein the content of the additive is 5 to 100 parts by weight with respect to 100 parts by weight of the base polymer of the composition forming the pressure-sensitive adhesive layer. 3. The dicing tape according to claim 1, which is used by bonding to an adherend having an uneven surface. 4. The dicing tape according to claim 3 , wherein the adherend having the uneven surface is a TSV wafer.

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