Adhesive sheet

Abstract

To provide an adhesive sheet which hardly causes cracking or chipping in a cutting step of cutting the adhesive sheet to which a semiconductor wafer is stuck, along the outer periphery of the semiconductor wafer so that the adhesive sheet has substantially the same shape as the semiconductor wafer.SOLUTION: The adhesive sheet includes an adhesive layer containing an adhesive composition, and has a room-temperature breaking elongation of 50% or more and 400% or less, a room-temperature breaking strength of 7MPa or more and 100MPa or less, and a die shear strength of 17MPa or more and 50MPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet. [Background technology]

[0002] Conventionally, in the manufacture of semiconductor devices, a dicing process is carried out on a semiconductor wafer to which an adhesive sheet has been attached, and a semiconductor chip is directly bonded to a circuit board via the adhesive sheet (see Patent Document 1).

[0003] In recent years, there has been a demand for miniaturized semiconductor chips to be mounted on products. To achieve this miniaturization, efforts are being made to thin semiconductor wafers. Thinning semiconductor wafers reduces the electrical resistance of semiconductor chips, enabling power savings, thereby reducing the area of ​​semiconductor chips and enabling miniaturization of semiconductor chips. In manufacturing miniaturized semiconductor chips, methods for facilitating the handling of thinned semiconductor wafers have been studied. Specifically, methods for attaching semiconductor wafers to carrier wafers that facilitate handling of semiconductor wafers have been studied.

[0004] To facilitate handling of the semiconductor wafer, an adhesive sheet attaching process is first performed, in which an adhesive sheet is attached to the semiconductor wafer. This is followed by a cutting process, in which the adhesive sheet is cut along the periphery of the semiconductor wafer so that the adhesive sheet has a shape substantially identical to that of the semiconductor wafer. Next, a carrier wafer bonding process is performed, in which the cut adhesive sheet is attached to the carrier wafer. This allows the semiconductor wafer to be attached to the carrier wafer via the adhesive sheet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-94870 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned cutting process has a problem in that the adhesive sheet is prone to cracking or chipping. If the adhesive sheet cracks or chips, the reliability of the semiconductor chip and, ultimately, the final product using the semiconductor chip will be reduced. Therefore, there is a demand for an adhesive sheet that is less likely to crack or chip.

[0007] Therefore, an object of the present invention is to provide an adhesive sheet that is less likely to crack or chip during a cutting process in which an adhesive sheet with a semiconductor wafer attached is cut along the outer periphery of the semiconductor wafer so that the adhesive sheet has approximately the same shape as the semiconductor wafer. [Means for solving the problem]

[0008] The adhesive sheet according to the present invention comprises: An adhesive sheet comprising an adhesive layer containing an adhesive composition, The breaking elongation at room temperature is 50% or more and 400% or less, The breaking strength at room temperature is 7 MPa or more and 100 MPa or less, The die shear strength at room temperature is 17 MPa or more and 50 MPa or less. [Effects of the Invention]

[0009] According to the present invention, an adhesive sheet is provided that is less likely to crack or chip during a cutting process in which an adhesive sheet with a semiconductor wafer attached is cut along the outer periphery of the semiconductor wafer so that the adhesive sheet has approximately the same shape as the semiconductor wafer. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows a schematic diagram of the semiconductor wafer bonding process. [Figure 2] Figure 2 shows a schematic diagram of the cutting process. [Figure 3]FIG. 3 shows a schematic diagram of the carrier wafer bonding process. [Figure 4] FIG. 4 shows a perspective view of an adhesive sheet according to an embodiment, which bonds a semiconductor wafer and a carrier wafer. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of the adhesive sheet according to the present invention will be described, taking an adhesive sheet for bonding wafers together as an example.

[0012] A method for manufacturing a semiconductor device including a power semiconductor element such as a power transistor generally includes a front-end process of forming a circuit surface on one side of a semiconductor wafer using highly integrated electronic circuits, and a back-end process of cutting semiconductor chips from the semiconductor wafer with the circuit surface formed thereon and assembling them. The front-end process includes, for example, a photolithography process in which a circuit pattern on a photomask is transferred onto the wafer by irradiating and exposing it with ultraviolet light or the like, and a planarization process in which irregularities on the wafer surface are smoothed. The back-end process includes, for example, a dicing process in which the semiconductor wafer is separated into individual semiconductor chips, and a die bonding process in which the semiconductor chips are fixed to an adherend such as a lead frame.

[0013] When the adhesive sheet 1 according to this embodiment is used in a method for manufacturing a semiconductor device, the pre-processing step further includes a carrier wafer bonding step of bonding a semiconductor wafer to a carrier wafer for facilitating handling of the semiconductor wafer via the adhesive sheet 1. A specific method for using the adhesive sheet 1, including the carrier wafer bonding step, is as follows.

[0014] As shown in Fig. 1, an adhesive sheet 1 according to this embodiment is attached onto a semiconductor wafer 2a (semiconductor wafer bonding step). Then, as shown in Fig. 2, the adhesive sheet 1 is cut along the outer periphery of the semiconductor wafer 2a using a cutting blade 3 so as to have substantially the same shape as the semiconductor wafer 2a (cutting step).

[0015] As shown in Fig. 3, a carrier wafer 2b is attached to the surface of the cut adhesive sheet 1 opposite to the surface to which the semiconductor wafer 2a is attached (carrier wafer bonding process). By carrying out the above process, the semiconductor wafer 2a and the carrier wafer 2b are bonded via the adhesive sheet 1, as shown in Fig. 4.

[0016] As described above, the adhesive sheet 1 according to this embodiment can be used to bond a plurality of wafers together.

[0017] The plurality of wafers may be, for example, silicon wafers, silicon carbide wafers, gallium phosphide wafers, indium phosphide wafers, gallium nitride wafers, etc. The plurality of wafers are preferably silicon wafers.

[0018] The plurality of wafers may be bare wafers, and more preferably are bare silicon wafers.

[0019] The adhesive sheet 1 of this embodiment is an adhesive sheet 1 having an adhesive layer containing an adhesive composition, and has a breaking elongation at room temperature of 50% or more and 400% or less, a breaking strength at room temperature of 7 MPa or more and 100 MPa or less, and a die shear strength at room temperature of 17 MPa or more and 50 MPa or less.

[0020] From the viewpoint of suppressing cracks or chips during the cutting step, the breaking elongation at room temperature is preferably 100% or more, more preferably 200% or more, even more preferably 300% or more, and particularly preferably 330% or more. From the viewpoint of suppressing cutting defects during the cutting step and suppressing the generation of chips due to cutting defects, the breaking elongation at room temperature is preferably 390% or less, more preferably 380% or less, even more preferably 375% or less, and particularly preferably 370% or less.

[0021] From the viewpoints of suppressing cracking or chipping during the cutting step and ensuring device reliability and ease of handling of the semiconductor wafer to which the carrier wafer is attached, the breaking strength at room temperature is preferably 20 MPa or more, more preferably 35 MPa or more, even more preferably 45 MPa or more, and particularly preferably 50 MPa or more. From the viewpoints of suppressing cutting defects during the cutting step and suppressing the generation of chips due to cutting defects, the breaking strength at room temperature is preferably 90 MPa or less, more preferably 80 MPa or less, even more preferably 70 MPa or less, and particularly preferably 65 MPa or less.

[0022] <Breaking elongation and breaking strength> The breaking elongation and breaking strength of the adhesive sheet 1 can be determined by the following method. A rectangular test piece with an initial length of 20 mm and a width of 10 mm is cut from adhesive sheet 1 so that the long axis is in the MD direction. Measurements are performed using the test piece under the following conditions. The elongation at which the test piece breaks (the ratio of the elongated length to the original length) is the breaking elongation, and the tensile force at which the test piece breaks is the breaking strength. Measurement equipment: Tensile testing machine (Shimadzu Corporation "AGS-H") Test piece: Initial length 20 mm, width 10 mm, strip shape, initial chuck distance 10 mm Pulling speed: 50mm / min ·Measurement temperature: 25℃

[0023] If the breaking elongation at room temperature and the breaking strength at room temperature are within the above ranges, chipping or cracking is less likely to occur when the adhesive sheet 1 is cut.

[0024] By adjusting the content of the acrylic resin or filler described below, the breaking elongation at room temperature and the breaking strength at room temperature can be adjusted to fall within the above-mentioned numerical ranges.

[0025] From the viewpoint of ensuring ease of handling of the semiconductor wafer to which the carrier wafer is attached, the die shear strength at room temperature is preferably 20 MPa or more, more preferably 23 MPa or more, even more preferably 24 MPa or more, and particularly preferably 25 MPa or more. The die shear strength at room temperature may be 45 MPa or less, 40 MPa or less, 35 MPa or less, or 30 MPa or less.

[0026] <Die shear strength> The die shear strength of the adhesive sheet 1 can be determined by the following method. A test piece is obtained by adhering adhesive sheet 1 diced to a size of 5 mm x 5 mm to a wafer diced to 10 mm x 10 mm. The test piece is prepared using a die bonder (Die Bonder DB830plus+ manufactured by Fasford Technology) under conditions of 130°C, a load of 0.2 MPa, and a bonding time of 2 seconds. Measurements are performed using the test piece under the following conditions. The measurement is performed approximately 20 seconds after placing the test piece on the measurement stage. Measurement equipment: Shear tester (Dage, Dage4000) ·Measurement speed (die shear speed): 500μm / sec Measurement gap (die shear height): 50 μm ·Measurement temperature: 25℃

[0027] When the die shear strength at room temperature is within the above range, chipping or cracking is less likely to occur when cutting the adhesive sheet 1. Furthermore, when the die shear strength at room temperature is within the above range, the adhesive sheet 1 exhibits excellent adhesive strength, and therefore when the adhesive sheet 1 is attached to a wafer, the adhesive sheet 1 is less likely to peel off from the wafer.

[0028] The die shear strength at room temperature can be adjusted to fall within the above range by adjusting the storage modulus at 150°C, the content of the acrylic resin, or the acid value of the acrylic resin, which will be described later.

[0029] In order to prevent the adhesive sheet 1 from adhering to the cutting blade during the cutting step, the adhesive sheet 1 according to this embodiment preferably has a melt viscosity at 120°C of 200 Pa·s or more, more preferably 1000 Pa·s or more, even more preferably 1500 Pa·s or more, particularly preferably 4000 Pa·s or more, and most preferably 5500 Pa·s or more. In order to improve the formability of the adhesive sheet, the melt viscosity is preferably 50000 Pa·s or less, more preferably 10000 Pa·s or less, and even more preferably 6000 Pa·s or less.

[0030] <Melt viscosity> The melt viscosity of adhesive sheet 1 at 120° C. can be determined by the following method. Adhesive sheet 1 is laminated to a thickness of 300 μm and punched into a circular shape with an 8 mm diameter punch to prepare a measurement sample. Measurements are carried out using this measurement sample under the following conditions. Measurement equipment: Rheometer (Thermo Scientific, HAAKE MARS III) Measuring jig: 8mmΦ Gap: 250μm Frequency: 5rad / sec Distortion: 10% ·Measurement temperature: 75~150℃ Heating rate: 10℃ / min

[0031] By ensuring that the melt viscosity at 120°C is within the above range, the cutting performance of the cutting blade can be prevented from decreasing, making it more unlikely that chipping or cracking will occur when the adhesive sheet 1 is cut.

[0032] The adhesive sheet 1 according to this embodiment preferably has a storage modulus of 10 MPa or more, more preferably 50 MPa or more, and even more preferably 100 MPa or more at 150° C. From the viewpoint of improving the formability of the adhesive sheet, the storage modulus is preferably 1000 MPa or less, more preferably 700 MPa or less, even more preferably 500 MPa or less, and particularly preferably 150 MPa or less.

[0033] <Storage modulus> The storage modulus of adhesive sheet 1 at 150° C. can be determined by the following method. Adhesive sheet 1 is laminated to a thickness of 200 μm to prepare a measurement sample having a width of 10 mm and a length of 40 mm. Measurements are carried out using this measurement sample under the following conditions. Measurement equipment: Dynamic viscoelasticity measuring equipment (RSA(III), manufactured by Rheometric Scientific) Chuck distance: 22.5mm Frequency: 10Hz ·Measurement temperature: 0~280℃ Heating rate: 10℃ / min

[0034] The storage modulus at 150°C can be adjusted to fall within the above range by adjusting the epoxy equivalent of the epoxy resin and the hydroxyl equivalent of the phenolic resin, or the content of the inorganic filler, as described below.

[0035] Having a storage modulus at 150°C within the above range reduces vibration of the adhesive sheet 1 when cutting the adhesive sheet 1, making chipping or cracking less likely to occur. Furthermore, reducing the vibration of the adhesive sheet 1 can prevent wire breakage and other wire bonding defects caused by vibration during the wire bonding process when the adhesive sheet 1 is used to bond semiconductor wafers, thereby achieving highly accurate wire bonding.

[0036] In the adhesive sheet 1 according to this embodiment, the adhesive composition may contain an acrylic resin (A), an epoxy resin (B), a phenolic resin (C), or a filler (D).

[0037] The acrylic resin (A) usually contains an acrylic monomer as a structural unit, such as (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate; (meth)acrylamide; and (meth)acrylonitrile.

[0038] The acrylic monomer may have an epoxy group. Examples of the acrylic monomer having an epoxy group include glycidyl (meth)acrylate.

[0039] The acrylic monomer may have a hydroxyl group or a carboxylic acid group.

[0040] In the adhesive sheet 1 according to this embodiment, from the viewpoint of improving the adhesion between the adhesive sheet 1 and the adherend, the acid value of the acrylic resin (A) is preferably 0.1 mgKOH / g or more, more preferably 1.0 mgKOH / g or more, even more preferably 2.5 mgKOH / g or more, and particularly preferably 4.0 mgKOH / g or more. From the viewpoint of improving the formability of the adhesive sheet, the acid value of the acrylic resin (A) is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less, even more preferably 30 mgKOH / g or less, particularly preferably 10 mgKOH / g or less, and most preferably 5.0 mgKOH / g or less.

[0041] The acid value of the acrylic resin (A) can be determined by the following measurement method in accordance with JIS K0070-1992 (potentiometric titration method). (1) Add phenolphthalein solution as an indicator to a mixed solvent of diethyl ether and ethanol in a volume ratio of 4:1 (volume of diethyl ether:volume of ethanol). Then, neutralize the mixed solvent containing the indicator using a 0.1 mol / L potassium hydroxide ethanol solution (titrant). This allows you to determine the factor f of the 0.1 mol / L potassium hydroxide ethanol solution (titrant). (2) Approximately 5 g of the sample (the acrylic resin) is weighed and placed in a beaker, and the mixed solvent is added to the beaker. The sample is dissolved in the mixed solvent while being heated and stirred. (3) Using a 0.1 mol / L potassium hydroxide ethanol solution (titrant), perform potentiometric titration of the mixed solvent in which the sample is dissolved. Then, calculate the acid value of the sample (the acrylic resin) according to the following formula (1). Acid value [mgKOH / g]=(B×f×5.611) / S...(1) B: Amount (mL) of 0.1 mol / L potassium hydroxide ethanol solution used in titration f: Factor of 0.1 mol / L potassium hydroxide ethanol solution S: mass of sample (g) 5.611: Formula weight of potassium hydroxide 56.11 x 10 -1

[0042] When the acid value of the acrylic resin (A) is within the above range, an adhesive sheet with excellent adhesive strength can be obtained.

[0043] From the viewpoint of adjusting the melt viscosity to an appropriate level, the content of the acrylic resin (A) in the adhesive composition is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 9% by mass or more, and particularly preferably 10% by mass or more. The lower the content of the acrylic resin (A) in the adhesive composition, the lower the melt viscosity. From the viewpoint of improving the formability of the adhesive sheet, the content of the acrylic resin (A) in the adhesive composition is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0044] Examples of the epoxy resin (B) include bisphenol A, bisphenol F, bisphenol S, brominated bisphenol A, hydrogenated bisphenol A, bisphenol AF, biphenyl, naphthalene, fluorene, phenol novolac, cresol novolac, trishydroxyphenylmethane, tetraphenylolethane, hydantoin, trisglycidyl isocyanurate, and glycidylamine epoxy resins. The epoxy resin (B) may be liquid or solid at room temperature.

[0045] In the adhesive sheet 1 according to this embodiment, from the viewpoint of increasing the storage modulus by increasing the crosslink density, the epoxy equivalent of the epoxy resin (B) (the mass of the resin containing one equivalent of epoxy groups) is preferably 190 g / eq or less, more preferably 185 g / eq or less, even more preferably 180 g / eq or less, particularly preferably 175 g / eq or less, and most preferably 170 g / eq or less. From the viewpoint of improving the formability of the adhesive sheet, the epoxy equivalent is preferably 10 g / eq or more, more preferably 60 g / eq or more, even more preferably 120 g / eq or more, and particularly preferably 160 g / eq or more.

[0046] The epoxy equivalent can be determined by the method specified in JIS K7236:2001.

[0047] In the adhesive sheet 1 according to the present embodiment, from the viewpoint of increasing the crosslink density and thereby increasing the storage modulus, the content of the epoxy resin (B) relative to 100 parts by mass of the acrylic resin (A) is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more. From the viewpoint of improving the formability of the adhesive sheet, the content of the epoxy resin (B) relative to 100 parts by mass of the acrylic resin (A) is preferably 350 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 75 parts by mass or less.

[0048] Examples of the phenol resin (C) include novolac type phenol resins, resol type phenol resins, and polyoxystyrenes such as polyparaoxystyrene.

[0049] Examples of novolac type phenolic resins include phenol novolac resins, phenol aralkyl resins (such as biphenyl aralkyl type phenolic resins), cresol novolac resins, tert-butylphenol novolac resins, nonylphenol novolac resins, and phenol xylylene resins.

[0050] In the adhesive sheet 1 according to this embodiment, from the viewpoint of increasing the crosslink density and thereby increasing the storage modulus, the hydroxyl equivalent of the phenolic resin (C) is preferably 190 g / eq or less, more preferably 170 g / eq or less, even more preferably 150 g / eq or less, particularly preferably 130 g / eq or less, and most preferably 110 g / eq or less. From the viewpoint of improving the formability of the adhesive sheet, the hydroxyl equivalent is preferably 10 g / eq or more, more preferably 50 g / eq or more, even more preferably 75 g / eq or more, and particularly preferably 100 g / eq or more.

[0051] The hydroxyl equivalent can be calculated from the following formula (2) using the hydroxyl value measured by the method specified in JIS K0070:1992 (potentiometric titration method). Hydroxyl equivalent weight [g / eq] = molecular weight of potassium hydroxide (56100) / hydroxyl value [mgKOH / g] (2)

[0052] When the epoxy equivalent and the hydroxyl equivalent are within the above ranges, wire bonding properties with higher accuracy can be obtained.

[0053] In the adhesive sheet 1 according to the present embodiment, from the viewpoint of increasing the crosslink density and thereby increasing the storage modulus, the content of the phenolic resin (C) relative to 100 parts by mass of the acrylic resin (A) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. From the viewpoint of improving the formability of the adhesive sheet, the content of the phenolic resin (C) relative to 100 parts by mass of the acrylic resin (A) is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 150 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 50 parts by mass or less.

[0054] The filler (D) may be an inorganic filler or an organic filler, and is preferably an inorganic filler.

[0055] Examples of inorganic fillers include fillers containing aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, boron nitride, and silica such as crystalline silica or amorphous silica. Examples of inorganic filler materials include simple metals such as aluminum, gold, silver, copper, and nickel, as well as alloys. Fillers such as aluminum borate whiskers, amorphous carbon black, and graphite are also acceptable. The filler may have various shapes, such as spherical, acicular, and flake-like. Only one or more of the above fillers may be used.

[0056] In the adhesive sheet 1 according to this embodiment, the content of the inorganic filler is preferably 20% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 50% by mass or less, even more preferably 35% by mass or more and 50% by mass or less, and particularly preferably 40% by mass or more and 50% by mass or less.

[0057] By ensuring that the content of the inorganic filler is within the above range, the storage modulus can be adjusted to an optimum value, thereby achieving wire bonding with even higher accuracy.

[0058] In the adhesive sheet 1 according to this embodiment, the adhesive composition may further contain an additive (E). Examples of the additive (E) include a curing catalyst and a silane coupling agent.

[0059] Examples of the curing catalyst include imidazole compounds, triphenylphosphine compounds, amine compounds, and trihalogen borane compounds. Examples of the imidazole compounds include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6 -[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Examples of triphenylphosphine compounds include triphenylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, tri(nonylphenyl)phosphine, diphenyltolylphosphine, tetraphenylphosphonium bromide, methyltriphenylphosphonium, methyltriphenylphosphonium chloride, methoxymethyltriphenylphosphonium, and benzyltriphenylphosphonium chloride. Triphenylphosphine compounds also include compounds having both a triphenylphosphine structure and a triphenylborane structure. Examples of such compounds include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-triborate, benzyltriphenylphosphonium tetraphenylborate, and triphenylphosphinetriphenylborane.Examples of amine compounds include monoethanolamine trifluoroborate and dicyandiamide. Examples of trihalogenborane compounds include trichloroborane. The adhesive sheet 1 may contain one type of curing catalyst or two or more types of curing catalysts.

[0060] Examples of the silane coupling agent include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropylmethyldiethoxysilane.

[0061] In the adhesive sheet 1 according to this embodiment, the content of the additive (E) relative to 100 parts by mass of the acrylic resin (A) may be 10 parts by mass or less, 5 parts by mass or less, or 2 parts by mass or less.

[0062] The thickness of the adhesive layer is not particularly limited, but may be, for example, 1 μm or more and 200 μm or less, 3 μm or more and 100 μm or less, or 5 μm or more and 50 μm or less.

[0063] The adhesive layer can be obtained by applying the adhesive composition to the surface of a resin film or the like using an applicator or the like, and then drying the applied adhesive composition.

[0064] The adhesive sheet 1 according to this embodiment may be composed of only an adhesive layer. The adhesive sheet 1 according to this embodiment may further include a substrate for supporting the adhesive layer. The substrate may be a sheet-like substrate. The adhesive sheet 1 according to this embodiment may include two or more adhesive layers.

[0065] The substrate is made of, for example, a metal foil, a fiber sheet, a rubber sheet, or a resin film. The substrate is preferably made of a resin film. The substrate may have a single-layer structure or a laminated structure. Examples of the fiber sheet include those made of paper, woven fabric, or nonwoven fabric.

[0066] Examples of materials for the resin film include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers; ethylene copolymers such as ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester random copolymers, and ethylene-(meth)acrylic acid ester alternating copolymers; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate; polyacrylates; polyvinyl chloride (PVC); polyurethanes; polycarbonates; polyphenylene sulfide; polyamides such as aliphatic polyamides and wholly aromatic polyamides (aramids); polyether ether ketones; polyimides; polyetherimides; polyvinylidene chloride; ABS (acrylonitrile-butadiene-styrene copolymers); cellulose or cellulose derivatives; silicone-containing polymers; and fluorine-containing polymers. These may be used alone or in combination of two or more.

[0067] The surface of the substrate on which the adhesive layer is laminated may be coated with a release agent (release agent) such as silicone resin or fluororesin to improve releasability.

[0068] The thickness of the substrate may be 25 μm or more and 200 μm or less, 30 μm or more and 150 μm or less, 35 μm or more and 100 μm or less, or 45 μm or more and 60 μm or less. The thickness of the substrate can be determined, for example, by measuring the thickness at five randomly selected points using a dial gauge (manufactured by PEACOCK, Model R-205) and calculating the arithmetic average of these thicknesses.

[0069] The adhesive sheet according to the present invention is not limited to the above-described embodiment. Furthermore, the adhesive sheet according to the present invention is not limited by the above-described effects. The adhesive sheet according to the present invention can be modified in various ways without departing from the spirit and scope of the present invention.

[0070] The adhesive sheet 1 of the present invention is not limited to being used for bonding multiple wafers together, but may also be used, for example, to bond a semiconductor element to a lead frame, or a semiconductor element to an organic substrate.

[0071] The shape of the adhesive sheet 1 according to the present invention is not particularly limited, and may be rectangular or circular.

[0072] The adhesive sheet 1 according to the present invention may have release films laminated on both sides.

[0073] The matters disclosed by this specification include the following.

[0074] (1) An adhesive sheet comprising an adhesive layer containing an adhesive composition, The breaking elongation at room temperature is 50% or more and 400% or less, The breaking strength at room temperature is 7 MPa or more and 100 MPa or less, The die shear strength at room temperature is 17 MPa or more and 50 MPa or less. Adhesive sheet. (2) The melt viscosity at 120°C is 200 Pa·s or more. The adhesive sheet according to (1). (3) The storage modulus at 150°C is 10 MPa or more. An adhesive sheet according to (1) or (2). (4) the adhesive composition comprises an epoxy resin and a phenolic resin, The epoxy equivalent of the epoxy resin is 190 g / eq or less, The hydroxyl group equivalent of the phenolic resin is 190 g / eq or less. The adhesive sheet according to any one of (1) to (3). (5) The adhesive composition further comprises an inorganic filler, The content of the inorganic filler is 20% by mass or more and 50% by mass or less. The adhesive sheet according to any one of (1) to (4). (6) the adhesive composition further comprises an acrylic resin, The acid value of the acrylic resin is 0.1 mgKOH / g or more. The adhesive sheet according to any one of (1) to (5). (7) Used to bond multiple wafers together, The adhesive sheet according to any one of (1) to (6). [Example]

[0075] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0076] The components of the adhesive compositions used in each of the Examples and Comparative Examples are as follows: (Acrylic resin (A)) A1: Nagase ChemteX Corporation, product name "SG-708-6", acid value = 9 mg KOH / g A2: Nagase ChemteX Corporation, product name "SG-70L", acid value = 4.5 mg KOH / g A3: Nagase ChemteX Corporation, product name "SG-N50", acid value = 35 mg KOH / g A4: Cemedine Co., Ltd., model number "AC-019", acid value = 0 mg KOH / g A5: Nagase ChemteX Corporation, product name "SG-N80", acid value = 10 mg KOH / g A6: Nagase ChemteX Corporation, product name "SG-70LN", acid value = 4.5 mg KOH / g A7: Manufactured by Negami Kogyo Co., Ltd., product name "W-197CM", acid value = 8.5mgKOH / g (Epoxy resin (B)) B1: Manufactured by Nippon Kayaku Co., Ltd., product name "EPPN-501HY", epoxy equivalent = 167g / eq B2: Manufactured by DIC Corporation, product name "N-665-EXP-S", epoxy equivalent = 167g / eq B3: Mitsubishi Chemical Corporation, product name "YL-980", epoxy equivalent = 180g / eq B4: Mitsubishi Chemical Corporation, product name "JER1004", epoxy equivalent = 925g / eq (Phenol resin (C)) C1: Gunei Chemical Industry Co., Ltd., product name "LVR-8210DL", hydroxyl equivalent = 104g / eq C2: Manufactured by Arakawa Chemical Industry Co., Ltd., product name "P-180", hydroxyl equivalent = 105g / eq C3: Manufactured by Meiwa Chemical Industry Co., Ltd., product name "MEHC-7851SS", hydroxyl equivalent = 203g / eq C4: Meiwa Chemical Industry Co., Ltd., product name "MEHC-7800H", hydroxyl equivalent = 190g / eq C5: Meiwa Chemical Industry Co., Ltd., product name "MEH-8005", hydroxyl equivalent = 135g / eq C6: Manufactured by Meiwa Chemical Industry Co., Ltd., product name "HF-1M", hydroxyl equivalent = 106g / eq C7: Manufactured by Meiwa Chemical Industry Co., Ltd., product name "MEHC-7851H", hydroxyl equivalent = 218g / eq C8: Mitsui Chemicals, Inc., product name "Milex XLC-CC", hydroxyl equivalent = 218g / eq (Inorganic filler (D)) D1: Spherical silica, manufactured by Admatechs Co., Ltd., product name "S0-25R" D2: Spherical silica, manufactured by Admatechs Co., Ltd., product name "SE-2050MCV" D3: Spherical silica, manufactured by Admatechs Co., Ltd., product name "SE-2050MNC" (Additive (E)) E1: Curing catalyst, manufactured by Hokko Chemical Industry Co., Ltd., product name "TPP-MK" E2: Curing catalyst, manufactured by Hokuko Chemical Industry Co., Ltd., product name "TPP-K" E3: Silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-303"

[0077] Example 1 The acrylic resin (A), epoxy resin (B), phenolic resin (C), inorganic filler (D), and additive (E) were mixed according to the formulation shown in Table 1, and the mixture was added to methyl ethyl ketone so that the solid content concentration was 40 mass % to obtain an adhesive composition. The obtained adhesive composition was applied to the silicone resin coated surface of a PET separator film (50 μm thick), and the solvent was removed by heating at 130°C for 2 minutes to prepare an adhesive sheet with a thickness of 25 μm.

[0078] (Examples 2 and 3, Comparative Examples 1 to 7) An adhesive sheet was prepared in the same manner as in Example 1, except that the acrylic resin (A), epoxy resin (B), phenolic resin (C), inorganic filler (D), and additive (E) used were changed to the compositions shown in Table 1.

[0079] <Breaking elongation and breaking strength> The adhesive sheets of each Example and Comparative Example were used to determine the breaking elongation and breaking strength at room temperature. A rectangular test piece with an initial length of 20 mm and a width of 10 mm was cut from the adhesive sheet with the long axis aligned in the MD direction. Measurements were carried out using the test piece under the following conditions. The elongation at which the test piece broke (the ratio of the elongated length to the original length) was taken as the breaking elongation, and the tensile force at which the test piece broke was taken as the breaking strength. Measurement equipment: Tensile testing machine (Shimadzu Corporation "AGS-H") Test piece: Initial length 20 mm, width 10 mm, strip shape, initial chuck distance 10 mm Pulling speed: 50mm / min ·Measurement temperature: 25℃

[0080] <Die shear strength> The die shear strength at room temperature was determined using the adhesive sheets of each Example and Comparative Example. A test piece was obtained by adhering a 5mm x 5mm diced adhesive sheet to a wafer diced to 10mm x 10mm. The test piece was prepared using a die bonder (Fasford Technology's DB830plus+ die bonder) at 130°C, a load of 0.2MPa, and a bonding time of 2 seconds. Measurements were performed using the test piece under the following conditions. The measurement was performed approximately 20 seconds after placing the test piece on the measurement stage. Measurement equipment: Shear tester (Dage, Dage4000) ·Measurement speed (die shear speed): 500μm / sec Measurement gap (die shear height): 50 μm ·Measurement temperature: 25℃

[0081] <Melt viscosity> The melt viscosity at 120°C was determined using the adhesive sheets of each Example and Comparative Example. The adhesive sheet was laminated to a thickness of 300 μm and punched into a circular shape with an 8 mm diameter punch to prepare a measurement sample. Measurements were carried out using the measurement sample under the following conditions. Measurement equipment: Rheometer (Thermo Scientific, HAAKE MARS III) Measuring jig: 8mmΦ Gap: 250μm Frequency: 5rad / sec Distortion: 10% ·Measurement temperature: 75~150℃ Heating rate: 10℃ / min

[0082] <Storage modulus> The storage modulus at 150°C was determined using the adhesive sheets of each Example and Comparative Example. The adhesive sheet was laminated to a thickness of 200 μm to prepare a measurement sample having a width of 10 mm and a length of 40 mm. Measurements were carried out using this measurement sample under the following conditions. Measurement equipment: Dynamic viscoelasticity measuring equipment (RSA(III), manufactured by Rheometric Scientific) Chuck distance: 22.5mm Frequency: 10Hz ·Measurement temperature: 0~280℃ Heating rate: 10℃ / min

[0083] <Cutting performance evaluation> The adhesive sheet of each example and comparative example was cut into a size of 10 μm thick and 230 mm wide, and then attached to a wafer using a tape application machine (manufactured by Nitto Seiki, DR3000II) to prepare a test sample. The test sample was again cut into a circular shape using a tape application machine (manufactured by Nitto Seiki, DR3000II). At this time, the table temperature was set to 70°C and the cutting blade temperature to 90°C. The size of chips and cracks from the wafer periphery was measured, and the smaller the size, the better the cutting performance was evaluated. The measurement was performed at eight locations, and the average of the measured values ​​was taken as the size of chips and cracks from the wafer periphery.

[0084] The evaluation results of each example and each comparative example are shown in Table 1.

[0085] [Table 1]

[0086] As can be seen from Table 1, the adhesive sheets of the examples that satisfy the constituent requirements of the present invention obtained better results in the cuttability evaluation than the adhesive sheets of the comparative examples.

[0087] From the above, it can be seen that the present invention can provide an adhesive sheet that is less likely to crack or chip during the cutting process in which an adhesive sheet with a semiconductor wafer attached is cut along the outer periphery of the semiconductor wafer so that it has approximately the same shape as the semiconductor wafer. [Explanation of symbols]

[0088] 1...adhesive sheet, 2a...semiconductor wafer, 2b...carrier wafer, 3...cutting blade

Claims

1. An adhesive sheet comprising an adhesive layer containing an adhesive composition, The breaking elongation at room temperature is 50% or more and 400% or less, The breaking strength at room temperature is 7 MPa or more and 100 MPa or less, The die shear strength is 17 MPa or more and 50 MPa or less. Adhesive sheet.

2. The melt viscosity at 120°C is 200 Pa s or more. The adhesive sheet according to claim 1 .

3. The storage modulus at 150°C is 10 MPa or more. The adhesive sheet according to claim 1 .

4. the adhesive composition comprises an epoxy resin and a phenolic resin, The epoxy equivalent of the epoxy resin is 190 g / eq or less, The hydroxyl group equivalent of the phenolic resin is 190 g / eq or less. The adhesive sheet according to claim 1 .

5. The adhesive composition further comprises an inorganic filler, The content of the inorganic filler is 20% by mass or more and 50% by mass or less. The adhesive sheet according to claim 1 .

6. the adhesive composition further comprises an acrylic resin, The acid value of the acrylic resin is 0.1 mgKOH / g or more. The adhesive sheet according to claim 1 .

7. Used to bond multiple wafers together, The adhesive sheet according to any one of claims 1 to 6.

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