Dicing tape and wafer processing method

Abstract

The purpose of the present disclosure is to provide a dicing tape having excellent wafer division characteristics during low-temperature expansion, and a wafer processing method in which the aforementioned dicing tape is used. The present disclosure relates to a dicing tape comprising a base material layer having an obverse surface and a reverse surface, and a first adhesive layer laminated on the obverse surface of the base material layer, the tensile storage elastic modulus of the base material layer at 0°C being 1.0 × 10 8 to 9.9 × 10 8 Pa, and the dynamic friction coefficient of an exposed surface on the reverse-surface side of the base material layer with respect to SUS304 at 0°C being 0.1-1.5.

Description

Dicing tape and wafer processing method

[0001] The present invention relates to a dicing tape and a wafer processing method.

[0002] When a semiconductor wafer (hereinafter also referred to as "wafer") or the like is diced, a dicing tape is attached to the wafer, the wafer is diced, and the dicing tape is expanded. After the expansion, the chips obtained by dicing the wafer are picked up (peeled) from the dicing tape.

[0003] Such dicing tapes include those laminated with a die attach film (DAF). For example, Patent Document 1 discloses a dicing tape-integrated adhesive sheet having a laminated structure of a substrate that serves as the dicing tape and a pressure-sensitive adhesive layer that serves as the DAF. In this sheet, the breaking strength and breaking elongation of the pressure-sensitive adhesive layer (DAF) are specified in terms of the divisibility of the pressure-sensitive adhesive layer (DAF).

[0004] Japanese Patent Application Laid-Open No. 2019-009324

[0005] In Patent Document 1, dividing grooves are formed on the wafer surface by blade dicing, and then back-grinding is performed from the back surface until the dividing grooves are reached, thereby singulating the wafer and forming chips. However, the method of dividing a wafer into chips is not limited to this. For example, methods such as stealth dicing, in which a modified portion is formed and the wafer is divided at the modified portion by a force that spreads in the surface direction of the expansion, and laser ablation dicing, in which the wafer is divided at the dividing grooves by a force that spreads in the surface direction of the expansion, are possible. Another possible method is to form dividing grooves on the wafer surface by blade dicing, and then divide the wafer at the dividing grooves by a force that spreads in the surface direction of the expansion.

[0006] Thus, when dicing a wafer by the force of expanding in the plane direction of the expander, the ability to separate the wafer into chips is more important than the ability to separate the adhesive layer (DAF) as in Patent Document 1. However, the dicing tape-integrated adhesive sheet described in Patent Document 1 does not mention dicing a wafer by the force of expanding in the plane direction of the expander at all.

[0007] The present invention has been made in view of the above problems, and has an object to provide a dicing tape that exhibits good wafer separation properties when expanded at low temperatures, and a wafer processing method using the dicing tape.

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by providing a dicing tape with a base layer having a predetermined tensile storage modulus and an exposed surface on the back side of the base layer having a predetermined dynamic friction coefficient, thereby completing the present invention.

[0009] That is, the present invention is as follows: [1] A sheet-like film having a base layer having a front surface and a back surface, and a first adhesive layer laminated on the front surface of the base layer, wherein the tensile storage modulus of the base layer at 0°C is 1.0 × 10 ８ ~9.9 x 10 ８[1] The dicing tape according to [1], wherein the base layer has a static friction coefficient of 0.1 to 1.5 at 0°C against SUS304, and wherein the dynamic friction coefficient of the exposed surface on the back surface of the base layer against SUS304 is 0.1 to 1.5. [2] The dicing tape according to [1], wherein the static friction coefficient of the exposed surface of the base layer against SUS304 is 0.1 to 1.5 at 0°C. [3] The dicing tape according to [1] or [2], wherein the base layer has an antistatic material or an antistatic layer on the back surface. [4] The dicing tape according to any of [1] to [3], wherein the dicing tape has a second adhesive layer on the first adhesive layer. [5] A wafer processing method comprising: a laminate fabrication step of fabricating a laminate in which the first adhesive layer or the second adhesive layer of the dicing tape according to any one of [1] to [4] is bonded to the surface of a wafer having a modified portion formed therein by laser dicing; a low-temperature expanding step of expanding the wafer by pushing up an expanding stage from the exposed surface side of the dicing tape under conditions of 0°C or less to form die chips from the wafer; and a pick-up step of picking up the die chips from the dicing tape. [6] The wafer processing method according to [5], further comprising an irradiation step of irradiating the first adhesive layer with ultraviolet light after the low-temperature expanding step. [7] The wafer processing method according to [6], when the dicing tape has the second adhesive layer, in the pick-up step, the second adhesive layer is peeled from the first adhesive layer after the ultraviolet irradiation, and the die chip with the second adhesive layer attached is picked up from the dicing tape. [8] The wafer processing method according to any one of [5] to [7], in which the surface of the wafer is a non-element forming surface. [9] The wafer processing method according to any one of [5] to [7], wherein the surface of the wafer is a device formation surface.

[10] The wafer processing method according to any one of [5] to [9], further comprising, after the low-temperature expanding step, a room-temperature expanding step of expanding by pushing up an expanding stage from the exposed surface side of the dicing tape under a condition of 5°C or higher.

[11] The wafer processing method according to any one of [5] to

[10] , further comprising a heat shrinking step of, after the low-temperature expanding step, heating a portion of the dicing tape that is not in contact with the wafer, thereby shrinking the base layer in the heated portion.

[0010] According to the present invention, it is possible to provide a dicing tape that exhibits good wafer divisibility when expanded at low temperatures, and a wafer processing method using the dicing tape.

[0011] FIG. 1(a) shows an example of a perspective view of the dicing tape of this embodiment, and FIG. 1(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 1(a). FIG. 2(a) shows an example of a perspective view of the laser dicing process, and FIG. 2(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 2(a). FIG. 3(a) shows an example of a perspective view of the back-grinding process, and FIG. 3(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 3(a). FIG. 4(a) shows an example of a perspective view of the lamination process, and FIG. 4(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 4(a). FIG. 5(a) shows an example of a perspective view of the laminate production process, and FIG. 5(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 5(a). FIG. 6(a) shows an example of a perspective view of the low-temperature expanding step, and FIG. 6(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 6(a). FIG. 7(a) shows an example of a perspective view of the room-temperature expanding step, and FIG. 7(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 7(a). FIG. 8(a) shows an example of a perspective view of the heat-shrinking step, and FIG. 8(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 8(a). FIG. 9(a) shows an example of a perspective view of the irradiation step, and FIG. 9(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 9(a). FIG. 10(a) shows an example of a perspective view of the pick-up step, and FIG. 10(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 10(a). An example of a perspective view of a wound dicing tape of this embodiment is shown.

[0012] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary. However, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0013] 1. Dicing Tape The dicing tape of this embodiment includes a base layer having a front surface and a back surface, and a first adhesive layer laminated on the surface of the base layer, and the tensile storage modulus of the base layer at 0°C is 1.0 × 10 ８ ~9.9 x 10 ８ Pa, and the dynamic friction coefficient of the exposed surface on the back side of the base layer against SUS304 at 0° C. is 0.1 to 1.5.

[0014] Fig. 1(a) shows an example of a perspective view of the dicing tape of this embodiment, and Fig. 1(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 1(a). As shown in Figs. 1(a) and 1(b), the dicing tape 100 of this embodiment has a base material layer 101 and a first adhesive layer 102 laminated on the front surface 101a of the base material layer 101, and may also have a second adhesive layer 103 disposed on the first adhesive layer 102 and an antistatic layer 104 disposed on the back surface 101b of the base material layer 101.

[0015] 1(a) and 1(b), an embodiment having a base layer 101, a first adhesive layer 102, and a second adhesive layer 103, or an embodiment having a base layer 101, a first adhesive layer 102, and an antistatic layer 104 may be used. Furthermore, an intermediate layer may be provided between the layers as needed from the viewpoint of adhesion and adhesiveness between the layers.

[0016] Next, as a premise for explaining the configuration of the dicing tape of this embodiment, a process of dividing the wafer 300 into die chips 303 by expanding will be explained. Fig. 6(a) shows an example of a perspective view of the low-temperature expanding process, and Fig. 6(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 6(a).

[0017] 6(a) and 6(b), by pushing up the expanding stage 402 against the dicing tape 100 fixed to the ring frame 401, tension is applied to the dicing tape 100 between the ring frame 401 and the wafer 300, causing the dicing tape 100 to expand in the planar direction. This force then causes the wafer 300 bonded to the dicing tape 100 to be divided at pre-formed modified sections 302, etc., to obtain individual die chips 303. Note that, at this time, the expanding may be performed at a relatively low temperature such as 0°C or -15°C, from the viewpoint of suppressing elongation of each adhesive layer and increasing tensile stress to facilitate division. This process is referred to as the "low-temperature expanding process."

[0018] In this way, in order to divide the wafer 300 into die chips 303 by low-temperature expansion, it is necessary that the external force applied to the dicing tape 100 by the expansion stage 402 be efficiently transmitted to the wafer 300 via the base material layer 101.

[0019] From this perspective, in this embodiment, the tensile storage modulus of the base layer 101 at low temperatures is specified. This improves the tension (restoring force) applied to the dicing tape 100 between the ring frame 401 and the wafer 300 in the low-temperature expanding step, improving the transferability of external forces to the wafer 300. This prevents defective division, such as when the modified portion 302 or the like prevents division, and further improves divisibility.

[0020] Furthermore, the coefficient of dynamic friction is temperature dependent. When the temperature is low and the friction of the exposed surface 100b against the expanding stage 402 increases, resulting in poor sliding, frictional vibrations occur during the low-temperature expanding process, and the tension (restoring force) of the modified section 302 suddenly changes. This can cause chipping or cracking of the chip during division, or roughness of the divided cross section, resulting in a decrease in the quality of the resulting die chip 303.

[0021] From this perspective, in this embodiment, the dynamic friction coefficient of the exposed surface 100b on the back surface 101b side of the base material layer 101 against SUS304 at low temperatures is specified. This suppresses frictional vibration and sudden changes in tension. As a result, the dividing cross sections of the modified portion 302 and the like become neater, further improving dividing quality.

[0022] Each of the components of the dicing tape of this embodiment will be described in detail below.

[0023] 1.1. Base Material Layer The dicing tape 100 of this embodiment has a base material layer 101 having a front surface 101a and a back surface 101b. The base material layer 101 preferably contains a resin. The resin is not particularly limited, but examples include ionomer resin, elastomer, polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, propylene-based copolymer, and ethylene-acrylic acid copolymer. These resins may be used alone or in combination of two or more. More specifically, the base material layer 101 may be a mixture, copolymer, or laminate of one of these resins with another.

[0024] Ionomer resins have a cross-linked structure formed by metal ions, and therefore can maintain shape stability even when exposed to temporary or localized high temperatures, such as those encountered during semiconductor processing.

[0025] The ionomer resin is not particularly limited as long as it is a resin in which a predetermined polymer is intermolecularly bonded by a metal ion, and examples thereof include polyolefin-based ionomers, (meth)acrylic ionomers, polystyrene-based ionomers, and polyester-based ionomers. These ionomer resins may be used alone or in combination of two or more. Among these, polyolefin-based ionomers and (meth)acrylic ionomers are preferred, and (meth)acrylic ionomers are more preferred.

[0026] The polyolefin ionomer is not particularly limited, but examples thereof include ethylene-methacrylate copolymers, ethylene-acrylate copolymers, and ethylene-methacrylate-acrylate copolymers.

[0027] The (meth)acrylic ionomer is not particularly limited, but examples thereof include an acrylic acid ester-acrylate copolymer, an acrylic acid ester-methacrylate copolymer, a methacrylic acid ester-acrylate copolymer, and a methacrylic acid ester-methacrylate copolymer.

[0028] The polystyrene ionomer is not particularly limited, but examples thereof include a styrene-styrene sulfonate copolymer, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, a styrene-styrene carboxylate copolymer, and a styrene-N-methyl 4-vinylpyridinium salt copolymer.

[0029] The polyester ionomer is not particularly limited, but examples thereof include sulfoterephthalic acid salt copolymerized polyethylene terephthalate, sulfoisophthalic acid salt copolymerized polyethylene terephthalate, sulfoterephthalic acid copolymerized polybutylene terephthalate, and sulfoisophthalic acid copolymerized polybutylene terephthalate.

[0030] The metal ions constituting the salt of the ionomer resin are not particularly limited, and examples thereof include monovalent metal ions such as sodium ions and lithium ions; divalent metal ions such as zinc ions, calcium ions, and magnesium ions; and trivalent metal ions such as aluminum ions, with zinc ions being preferred. The polymer and metal ions in the ionomer resin can be used in any combination based on the valence of the ionic functional group in the polymer and the metal ion.

[0031] The elastomer is not particularly limited, but examples thereof include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, silicone rubber, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin such as 6-nylon and 6,6-nylon, (meth)acrylic resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polyamideimide resin, fluororesin, and phenoxy resin. These elastomers may be used alone or in combination of two or more.

[0032] The content of the resin in the base material layer 101 is preferably 80 to 100 mass %, 85 to 98 mass %, or 90 to 95 mass %, based on the entire base material layer 101 .

[0033] The base layer 101 may contain additives other than resins as needed. Examples of additives include, but are not limited to, plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, processing aids, antistatic agents, and friction reducers. The additives may be used alone or in combination of two or more.

[0034] The content of the additive is preferably 0.1 to 10.0 mass %, 0.5 to 5.0 mass %, or 1.0 to 2.5 mass %, based on the entire substrate layer 101 .

[0035] The antistatic agent is not particularly limited, but examples thereof include carbon nanotubes, metal oxides, polythiophene, polyaniline, polypyrrole, dimethylaminoethyl (meth)acrylate quaternary chloride, diethylaminoethyl (meth)acrylate quaternary chloride, methylethylaminoethyl (meth)acrylate quaternary chloride, p-dimethylaminostyrene quaternary chloride, p-diethylaminostyrene quaternary chloride, acrylic polymers having a quaternary ammonium salt in the side chain, and quaternary ammonium salt-type acrylic polymers. The antistatic agents may be used alone or in combination of two or more.

[0036] The friction reducer is not particularly limited, but examples thereof include silicone resins, fluororesins, (modified) silicone oils, waxes, fatty acid esters, and fatty acid amides. These friction reducers may be used as a mixture of multiple components. Silicone graft copolymers are particularly preferred.

[0037] Examples of silicone graft copolymers include vinyl polymers obtained by polymerizing a monomer having a vinyl group such as a (meth)acryloyl group or a styryl group at the end of the silicone molecular chain (hereinafter referred to as a "silicone monomer") with a (meth)acrylic monomer, a monomer having a vinyl group such as styrene, or the like.

[0038] Examples of the (meth)acrylic monomer used in the silicone graft copolymer include alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, modified hydroxy (meth)acrylate, and (meth)acrylic acid, with alkyl (meth)acrylate being preferred.

[0039] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate, and hydroxyalkyl (meth)acrylates.

[0040] Examples of the hydroxyalkyl (meth)acrylate include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

[0041] Examples of the modified hydroxy(meth)acrylate include ethylene oxide-modified hydroxy(meth)acrylate and lactone-modified hydroxy(meth)acrylate.

[0042] The thickness of the base layer 101 is preferably 10 to 500 μm, 25 to 250 μm, or 50 to 100 μm. When the thickness of the base layer 101 is within the above range, the external force applied to the dicing tape during the low-temperature expanding process is more easily transmitted to the wafer 300, which tends to result in improved divisibility of the wafer 300.

[0043] The substrate layer 101 may be a single layer or multi-layer structure comprising the materials described above.

[0044] The tensile storage modulus of the base layer 101 at 0°C is 1.0 × 10 ８ ~9.9 x 10 ８ Pa, preferably 1.5×10 ８ ~9.0 x 10 ８ Pa, 2.0 × 10 ８ ~8.5 x 10 ８ Pa, 2.5 × 10 ８ ~8.0 x 10 ８ Pa. When the tensile storage modulus at 0° C. is within the above range, the divisibility of the wafer 300 tends to be further improved.

[0045] The tensile storage modulus of the base layer 101 at −15° C. is preferably 1.0×10 ８ ~9.9 x 10 ８ Pa, 2.0 × 10 ８ ~9.5 x 10 ８ Pa, 2.5 × 10 ８ ~9.0 x 10 ８ Pa, 3.0 × 10 ８ ~8.5 x 10 ８ It is Pa.

[0046] The tensile storage modulus at −15° C. to 0° C. can be adjusted by the type and composition of the resin constituting the base layer 101 .

[0047] In this embodiment, -15 to 0°C is used as a reference value for the low temperature in low-temperature expansion. Depending on the specifications of the low-temperature expansion equipment, it is also possible that low-temperature expansion may be performed at a temperature higher or lower than -15 to 0°C. However, even if the actual low temperature during low-temperature expansion is not -15 to 0°C, but is higher or lower than this, it can be said that the divisibility of the wafer 300 is improved by ensuring that the tensile storage modulus and dynamic friction coefficient measured based on -15 to 0°C satisfy the specified range. Similarly, the static friction coefficient is also a value measured based on -15 to 0°C. Unless otherwise specified, in this specification, the measurement temperatures for the tensile storage modulus, dynamic friction coefficient, and static friction coefficient are -15 to 0°C.

[0048] In addition, in this embodiment, the deformation mode when measuring the storage modulus is set to tensile because, from the perspective of the divisibility of the wafer 300, the physical properties of the dicing tape 100 against external forces in the surface direction are of concern.

[0049] The tensile storage modulus is measured in accordance with the storage modulus in the tensile mode described in JIS K7244-1:1998, except that the temperature condition is -15°C to 0°C.

[0050] The dynamic friction coefficient of the exposed surface 100b on the back surface 101b side of the base layer 101 against SUS304 at 0°C is 0.1 to 1.5, preferably 0.1 to 1.0, 0.1 to 0.8, 0.1 to 0.7, or 0.1 to 0.6. When the dynamic friction coefficient at 0°C is within the above range, the divisibility of the wafer 300 tends to be further improved.

[0051] The dynamic friction coefficient of the exposed surface 100b on the back surface 101b side of the base layer 101 against SUS304 at −15° C. is preferably 0.1 to 1.0, 0.1 to 0.8, or 0.1 to 0.6.

[0052] In this embodiment, the exposed surface 100b on the back surface 101b side of the base layer 101 may be the back surface 101b of the base layer 101 itself, or, if another layer is laminated on the back surface 101b side of the base layer 101, may be the surface of the other layer opposite to the base layer 101. For example, in the dicing tape 100 shown in FIG. 1 , the exposed surface 100b on the back surface 101b side of the base layer 101 is the surface of the antistatic layer 104 that is not in contact with the base layer 101.

[0053] When the exposed surface 100b is the back surface 101b of the base layer 101 itself, the dynamic friction coefficient at -15°C to 0°C can be adjusted by the type and composition of the resin constituting the base layer 101 and the surface roughness of the back surface 101b. The surface roughness of the back surface 101b can be adjusted, for example, by providing irregularities through texturing. Furthermore, when the exposed surface 100b is the surface of another layer, such as the antistatic layer 104, laminated on the back surface 101b side of the base layer 101, the dynamic friction coefficient can be adjusted by the type and composition of the resin constituting the other layer and the surface roughness of the surface of the other layer. The surface roughness of the surface of the other layer can be adjusted, for example, by providing irregularities through texturing.

[0054] The static friction coefficient of the exposed surface 100b on the back surface 101b side of the base layer 101 against SUS304 at 0°C is preferably 0.1 to 1.5, 0.1 to 1.0, 0.1 to 0.8, 0.1 to 0.7, or 0.1 to 0.6. When the static friction coefficient at 0°C is within the above range, smooth expansion with a smaller external force becomes possible when low-temperature expansion of the dicing tape to which the wafer is bonded is initiated, which tends to further improve the divisibility of the wafer 300. The static friction coefficient at 0°C can be adjusted in the same manner as the kinetic friction coefficient.

[0055] The static friction coefficient of the exposed surface 100b on the back surface 101b side of the base layer 101 against SUS304 at −15° C. is preferably 0.1 to 1.0, 0.1 to 0.8, or 0.1 to 0.6.

[0056] In this embodiment, the dynamic friction coefficient of the exposed surface on the back side of the base layer of the dicing tape relative to SUS304 is measured. Depending on the specifications of the low-temperature expanding equipment, the expansion stage, which is the base on which the dicing tape is placed during expansion, may be made of a material other than SUS304, such as martensitic stainless steels such as SUS410, SUS403, and SUS630, austenitic stainless steels such as SUS303 and SUS316, ferritic stainless steels such as SUS430, or other metals. However, since the dynamic friction coefficients of SUS304 and other stainless steels and metals tend to be similar, if the dynamic friction coefficient measured relative to SUS304 falls within a predetermined range, the divisibility of the wafer 300 is improved. The same applies to the static friction coefficient.

[0057] The dynamic friction coefficient and static friction coefficient are measured in accordance with JIS K7125 using SUS304 with a BA-finished surface as the mating material, except that the temperature condition is -15°C to 0°C.

[0058] 1.2. First Adhesive Layer The dicing tape 100 of this embodiment has a first adhesive layer 102 laminated on the surface of the base layer 101. The first adhesive layer 102 contributes to the adhesion between the base layer 101 and the wafer 300 or the second adhesive layer 103. It is preferable that the first adhesive layer 102 maintains the adhesion between the base layer 101 and the wafer 300 or the second adhesive layer 103 until the pick-up step so that the die chip 303 does not fall off. On the other hand, in the pick-up step, it is preferable that the adhesive strength of the first adhesive layer 102 to the wafer 300 or the second adhesive layer 103 is reduced from the viewpoint of improving the pick-up ability of the die chip 303.

[0059] From this perspective, in order to change the adhesive strength depending on the irradiation process, it is preferable that the first adhesive layer 102 contains a base polymer having a polymerizable carbon-carbon double bond and a photopolymerization initiator, and may further contain additives such as a curing agent.

[0060] In the above description, the wafer 300 or the second adhesive layer 103 is peeled from the first adhesive layer 102, assuming that the first adhesive layer 102 is left on the surface of the base material layer 101, in the pick-up step. However, this embodiment is not limited to this, and peeling may occur at the interface between the base material layer 101 and the first adhesive layer 102, and the first adhesive layer 102 may be picked up in a state where it is attached to the surface of the die chip 303. In this case, the first adhesive layer 102 may function as a die attach film (DAF) when mounting the die chip 303 on a substrate.

[0061] The first adhesive layer 102 may be disposed only on the portion of the dicing tape 100 on which the wafer 300 is disposed, or the first adhesive layer 102 may be formed in a portion other than the above-mentioned portion.

[0062] 1.2.1 Base Polymer The base polymer having a polymerizable carbon-carbon double bond is the main component of the first adhesive layer 102. When the first adhesive layer 102 is irradiated with ultraviolet light, the photopolymerization initiator generates radicals, which polymerize the polymerizable carbon-carbon double bonds of the base polymer. As a result, after ultraviolet light irradiation, the base polymers become crosslinked with each other, reducing their adhesive strength.

[0063] The base polymer is not particularly limited, but examples thereof include (meth)acrylic acid ester copolymers having polymerizable double bonds. The shape of the (meth)acrylic acid ester copolymer is not particularly limited, but examples thereof include linear, branched, or crosslinked shapes. Among these, a crosslinked shape is preferable. By using such a base polymer, the cohesive force of the first adhesive layer 102 is improved, the adhesion to the wafer is further improved, and contamination tends to be further reduced. A base polymer having a crosslinked or branched shape may be a base polymer having a linear shape, in which some of the polymerizable double bonds have been bonded by aging or the like.

[0064] The (meth)acrylic acid ester monomer constituting the (meth)acrylic acid ester-based copolymer is not particularly limited, and examples thereof include alkyl (meth)acrylates having a linear or branched alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl. These alkyl (meth)acrylates may be used alone or in combination of two or more.

[0065] The monomer component other than the alkyl (meth)acrylate is not particularly limited, but examples thereof include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctadecyl (meth)acrylate; hydroxyl group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl(meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethylacryloylphosphate. These other monomers may be used alone or in combination of two or more.

[0066] Among these, (meth)acrylic acid ester copolymers containing alkyl (meth)acrylate and a carboxyl group-containing monomer, and (meth)acrylic acid ester copolymers containing alkyl (meth)acrylate and a hydroxyl group-containing monomer are preferred.

[0067] The method for introducing a polymerizable double bond into a (meth)acrylic acid ester copolymer is not particularly limited, and examples thereof include a method in which a modifying agent having a polymerizable double bond is reacted with a carboxyl group of a carboxyl group-containing monomer, a carboxyl anhydride group of an acid anhydride monomer, or a hydroxyl group of a hydroxyl group-containing monomer.

[0068] For example, by reacting an isocyanate compound having a polymerizable double bond as a modifier with a (meth)acrylic acid ester copolymer containing a hydroxyl group-containing monomer unit, a polymerizable double bond can be introduced into the hydroxyl group-containing monomer unit via a urethane bond.

[0069] In addition, by reacting an epoxy compound having a polymerizable double bond as a modifier with a (meth)acrylic acid ester copolymer containing a carboxyl group-containing monomer unit, a polymerizable double bond can be introduced into the carboxyl group-containing monomer unit via an ester bond. As another example, by reacting an isocyanate compound having a polymerizable double bond as a modifier with a (meth)acrylic acid ester copolymer containing a carboxyl group-containing monomer unit, a polymerizable double bond can be introduced into the carboxyl group-containing monomer unit via an amide bond.

[0070] The modifier is not particularly limited as long as it has a functional group that reacts with the functional group of the (meth)acrylic acid ester copolymer and has a polymerizable double bond. Examples of the modifier include an epoxy compound having a polymerizable double bond and an isocyanate compound having a polymerizable double bond, such as 2-methacryloyloxyethyl isocyanate.

[0071] The double bond content of the base polymer is preferably 5 to 50 mol%, 10 to 45 mol%, 15 to 40 mol%, or 20 to 35 mol%, relative to 100 mol% of the monomers constituting the base polymer. When the double bond content of the base polymer is within the above range, the crosslinking reaction of the polymerizable double bonds of the base polymer proceeds sufficiently upon UV irradiation, and the contact area with the wafer is reduced due to cure shrinkage, thereby sufficiently reducing adhesive strength. In other words, easy peeling is achieved, further improving pickup performance. In addition, monomer components that could not be polymerized during polymer component synthesis may be able to react with double bonds in the polymer component side chains upon UV irradiation, which also leads to reduced adhesive residue.

[0072] The base polymer preferably has a hydroxyl group. The hydroxyl group may be derived from a hydroxyl group-containing monomer unit or the like, may be derived from a modifier, or may be a hydroxyl group generated by the reaction of a monomer unit such as a hydroxyl group-containing monomer unit with a modifier. An example of a hydroxyl group generated by the reaction of a carboxyl group-containing monomer with a modifier is a reaction of a carboxyl group-containing monomer with an epoxy compound having a polymerizable double bond.

[0073] Because the base polymer has hydroxyl groups, when a curing agent described below is blended, further cross-linking between multiple polymers can be achieved via the hydroxyl groups, which tends to further improve the cohesive strength of the first adhesive layer 102. In addition, the anchoring ability between the substrate layer 101 and the first adhesive layer 102 is also further improved, cohesive failure and anchor failure are suppressed, and more stable adhesive properties tend to be obtained.

[0074] Among the monomer units contained in the base polymer, the content of monomer units having a hydroxyl group is preferably 1 to 40 mol %, 3 to 30 mol %, or 5 to 25 mol %, relative to 100 mol % of all monomer units. When the content of monomer units having a hydroxyl group is within the above range, the cohesive strength of the first adhesive layer 102 tends to be further improved.

[0075] The content of the base polymer is preferably 80 to 99.5 mass %, 85 to 99.5 mass %, or 90 to 99.5 mass %, relative to the total amount of the first adhesive layer 102. When the content of the base polymer is within the above range, contamination tends to be further suppressed.

[0076] 1.2.2. Photopolymerization Initiator The photopolymerization initiator is not particularly limited, but examples thereof include alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, aromatic ketones, aromatic onium salt compounds, organic peroxides, thio compounds (e.g., thiophenyl group-containing compounds), α-aminoalkylphenone compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds. Among these, alkylphenone-based photopolymerization initiators are preferred. These photopolymerization initiators may be used alone or in combination of two or more.

[0077] The content of the photopolymerization initiator is preferably 0.1 to 5.0 mass %, 0.5 to 4.5 mass %, or 1.0 to 4.0 mass %, relative to the total amount of the first adhesive layer 102. When the content of the photopolymerization initiator is within the above range, contamination tends to be further suppressed.

[0078] 1.2.3. Additives The first adhesive layer 102 may contain additives such as a curing agent, a tackifier, a crosslinking retarder, and an antioxidant.

[0079] The curing agent is not particularly limited, but examples thereof include isocyanate-based compounds, epoxy-based compounds, and amine-based compounds. Among these, isocyanate-based compounds are preferred. Use of such a curing agent tends to further improve the cohesive strength of the first adhesive layer 102. These curing agents may be used alone or in combination of two or more.

[0080] The isocyanate compound is not particularly limited, and examples thereof include compounds having a group that reacts with a hydroxyl group or a carboxyl group of the base polymer, and more specific examples thereof include tolylene diisocyanates such as trimethylolpropane-adducted tolylene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate and xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate and methylene bis(4-cyclohexyl isocyanate), and aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. These isocyanate compounds may be used alone or in combination of two or more.

[0081] Among these, a polyfunctional isocyanate compound having two or more functional groups is preferred as the curing agent. By using such a curing agent, the multiple base polymers can be crosslinked by the curing agent, which tends to further improve the cohesive strength of the first adhesive layer 102. In addition, the anchoring ability between the substrate layer and the first adhesive layer 102 also improves, which tends to result in more stable adhesive properties.

[0082] The content of the curing agent is preferably 0.1 to 5.0 parts by mass, more preferably 0.2 to 4.5 parts by mass, and even more preferably 0.3 to 4.0 parts by mass, relative to 100 parts by mass of the base polymer. When the content of the curing agent is 0.1 parts by mass or more, the crosslink density of the first adhesive layer 102 is further improved, cohesive failure that occurs during peeling is further suppressed, and contamination caused by cohesive failure tends to be further suppressed. Furthermore, when the content of the curing agent is 5.0 parts by mass or less, the crosslink density is further reduced, and the elastic modulus is lowered, which tends to further improve adhesive strength.

[0083] The content of the curing agent is preferably 0.1 to 5.0 mass %, 0.2 to 4.5 mass %, or 0.3 to 4.0 mass %, relative to the total amount of the first adhesive layer 102. When the content of the curing agent is within the above range, contamination tends to be further suppressed.

[0084] The tackifier is not particularly limited, but examples thereof include petroleum-based resins, terpene resins, terpene-phenolic resins, aromatic-modified terpene resins, coumarone-indene resins, natural resin rosin, modified rosin, glycerin ester rosin, pentaerythritol ester rosin, phenolic resins, xylene resins, alicyclic petroleum resins, styrene-based resins, and dicyclopentadiene resins. These tackifiers may be used alone or in combination. The content of the tackifier is preferably 0.1 to 2.0% by mass, 0.2 to 1.5% by mass, or 0.3 to 1.0% by mass, relative to the total amount of the first adhesive layer 102.

[0085] The crosslinking retarder is not particularly limited, but may be, for example, a compound that can suppress excessive viscosity increase in a pressure-sensitive adhesive composition containing an isocyanate-based curing agent by blocking the isocyanate groups of the curing agent. Examples of such crosslinking retarders include, but are not limited to, β-diketones such as acetylacetone, hexane-2,4-dione, heptane-2,4-dione, and octane-2,4-dione; β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; and benzoylacetone. These crosslinking retarders may be used alone or in combination of two or more. The content of the crosslinking retarder is preferably 0.1 to 2.0% by mass, 0.2 to 1.5% by mass, or 0.3 to 1.0% by mass, relative to the total amount of the first adhesive layer 102.

[0086] The antioxidant is not particularly limited, but examples thereof include methylhydroquinone, hydroquinone, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), catechol, hydroquinone monomethyl ether, monotert-butylhydroquinone, 2,5-ditert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-ditert-butyl-p-benzoquinone, picric acid, citric acid, phenothiazine, tert-butylcatechol, 2-butyl-4-hydroxyanisole, 2,6-ditert-butyl-p-cresol, and 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-ditert-butylphenol. These antioxidants may be used alone or in combination of two or more. The content of the antioxidant relative to the total amount of the first adhesive layer 102 is preferably 0.1 to 2.0 mass %, 0.2 to 1.5 mass %, or 0.3 to 1.0 mass %.

[0087] The thickness of the first adhesive layer 102 is typically 1.0 to 250 μm, preferably 2.0 to 50 μm, and more preferably 5.0 to 40 μm. By making the thickness of the adhesive layer 102 1.0 μm or more, sufficient adhesive strength can be ensured, making it easier to prevent the scattering of semiconductor chips separated by expanding. Furthermore, by making the thickness of the adhesive layer 250 μm or less, costs tend to be further reduced.

[0088] 1.3. Second Adhesive Layer The dicing tape 100 of this embodiment may have a second adhesive layer 103 on the first adhesive layer 102. The second adhesive layer 103 contributes to the adhesion between the first adhesive layer 102 and the wafer 300. In addition, peeling may occur at the interface between the second adhesive layer 103 and the first adhesive layer 102 during the pick-up process, and the second adhesive layer 103 may be picked up in a state where it is attached to the surface of the die chip 303. In this case, the second adhesive layer 103 may function as a die attach film (DAF) when mounting the die chip 303 on a substrate.

[0089] The second adhesive layer 103 may be disposed only on the portion of the dicing tape 100 on which the wafer 300 is disposed, or the second adhesive layer 103 may be formed in a portion other than the above-mentioned portion.

[0090] From this viewpoint, it is preferable that the adhesive strength of the second adhesive layer 103 does not change depending on the irradiation process, and it is preferable that the second adhesive layer 103 does not contain a photoreactive compound such as a base polymer having a polymerizable carbon-carbon double bond or a photopolymerization initiator.

[0091] The second adhesive layer 103 may be made of various materials, or may be a commercially available die attach film. When making the second adhesive layer 103, the material is not particularly limited, but examples thereof include epoxy resin, polyurethane resin, phenolic resin, elastomer, silane coupling agent, curing agent, inorganic filler, and curing accelerator.

[0092] The epoxy resin is not particularly limited, but examples thereof include cresol novolac epoxy resins, epoxy resins having an alicyclic structure, and aromatic epoxy resins. These epoxy resins may be used alone or in combination of two or more.

[0093] The content of the epoxy resin relative to the total amount of resin in the second adhesive layer 103 is preferably 3 to 70 mass %, 10 to 60 mass %, or 15 to 50 mass %.

[0094] The polyurethane resin is not particularly limited, but examples thereof include polyurethane resins having an alicyclic structure, aromatic polyurethane resins, and linear polyurethane resins. These polyurethane resins may be used alone or in combination of two or more.

[0095] The content of the polyurethane resin is preferably 3 to 35% by mass, and more preferably 5 to 30% by mass, relative to the total amount of resin in the second adhesive layer 103 .

[0096] The phenolic resin is not particularly limited, but examples thereof include novolac-type phenolic resins and resol-type phenolic resins. These phenolic resins may be used alone or in combination of two or more.

[0097] The content of the phenol resin relative to the total amount of resin in the second adhesive layer 103 is preferably 3 to 70 mass %, 10 to 60 mass %, or 15 to 50 mass %.

[0098] The elastomer is not particularly limited, but examples thereof include natural rubber, acrylic rubber, butyl rubber, isoprene rubber, chloroprene rubber, silicone rubber, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin such as 6-nylon and 6,6-nylon, (meth)acrylic resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polyamideimide resin, fluororesin, and phenoxy resin. These elastomers may be used alone or in combination of two or more.

[0099] The content of the elastomer relative to the total amount of resin in the second adhesive layer 103 is preferably 100 to 500 mass %, 150 to 450 mass %, or 200 to 400 mass %.

[0100] The silane coupling agent is not particularly limited, but examples thereof include epoxy-based silane coupling agents, amino-based silane coupling agents, mercapto group-containing silane coupling agents, and ureido group-containing silane coupling agents. These silane coupling agents may be used alone or in combination of two or more.

[0101] The content of the silane coupling agent is preferably 1 to 10% by mass, and more preferably 2 to 8% by mass, relative to the total amount of the resin in the second adhesive layer 103 .

[0102] The curing agent is not particularly limited, but examples thereof include phenolic resins, ester compounds, aromatic amines, aliphatic amines, and acid anhydrides. These curing agents may be used alone or in combination of two or more.

[0103] The content of the curing agent is preferably 3 to 30% by mass, and more preferably 5 to 25% by mass, relative to the total amount of the resin in the second adhesive layer 103 .

[0104] The inorganic filler is not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, boron nitride, crystalline silica, and amorphous silica. These curing agents may be used alone or in combination of two or more.

[0105] The content of the inorganic filler is preferably 3 to 50% by mass, and more preferably 10 to 45% by mass, relative to the total amount of resin in the second adhesive layer 103 .

[0106] The curing accelerator is not particularly limited, but examples thereof include imidazoles and their derivatives, organic phosphorus compounds, secondary amines, tertiary amines, and quaternary ammonium salts. These curing accelerators may be used alone or in combination of two or more.

[0107] The content of the curing accelerator relative to the total amount of resin in the second adhesive layer 103 is not particularly limited, but is, for example, 0.01 to 1.00 mass %, or 0.05 to 0.50 mass %.

[0108] The thickness of the second adhesive layer 103 is not particularly limited, but is, for example, 1 to 100 μm, 5 to 90 μm, or 10 to 80 μm.

[0109] 1.4. Antistatic Layer The dicing tape 100 of this embodiment may have an antistatic layer 104 on the back surface side of the base layer 101. The antistatic layer 104 may be a layer composed of only an antistatic agent, a layer composed of an antistatic agent and other components, or a layer containing an antistatic agent and other components in a matrix such as an organic binder. Examples of other components include a friction reducer.

[0110] 1.4.1 Organic Binder The organic binder is not particularly limited, but examples thereof include acrylic resins, urethane resins, polyester resins, epoxy resins, polyvinyl chloride resins, melamine resins, polyimide resins, and silicone resins.

[0111] The acrylic resin is a polymer of a vinyl compound having a (meth)acrylic acid monomer unit or a (meth)acrylic acid ester monomer unit, and may also have a monomer unit derived from a functional group-containing monomer, such as styrene, vinyl toluene, allyl acetate, (meth)acrylonitrile, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate, vinyl ethyl ether, vinyl propyl ether, or vinyl isobutyl ether.

[0112] The (meth)acrylic acid ester monomer is not particularly limited, but examples thereof include butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, etc. A plurality of (meth)acrylic acid ester monomer components may be used in combination.

[0113] The functional group-containing monomer is not particularly limited, but examples thereof include monomers having a functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an amide group, an amino group, a methylol group, a sulfonic acid group, a sulfamic acid group, or a phosphate (or phosphorous) ester group.

[0114] Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0115] Examples of the monomer having a carboxyl group include (meth)acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamido-N-glycolic acid, and cinnamic acid.

[0116] Examples of the monomer having an epoxy group include allyl glycidyl ether and (meth)acrylic acid glycidyl ether.

[0117] Examples of monomers having an amide group include (meth)acrylamide. Examples of monomers having an amino group include N,N-dimethylaminoethyl (meth)acrylate. Examples of monomers having a methylol group include N-methylolacrylamide. A plurality of functional group-containing monomers may be used in combination.

[0118] In addition to the above monomers, for example, styrene, vinyl toluene, allyl acetate, (meth)acrylonitrile, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate, vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether, etc. may be appropriately used in the (meth)acrylic acid ester polymer.

[0119] 1.4.2. Antistatic Agent The antistatic agent is not particularly limited, but examples thereof include those exemplified as additives for the base layer.

[0120] When the antistatic agent is a substance having adhesive properties such that the antistatic agent alone can adhere to the substrate, such as a quaternary ammonium salt-type acrylic polymer, an organic binder is not required, and the antistatic layer 104 may consist solely of the antistatic agent, or may consist of an antistatic agent and other components such as a friction reducer. On the other hand, when the antistatic agent is a substance such as carbon nanotubes that cannot adhere to the substrate alone, the antistatic layer 104 preferably contains an organic binder. When the antistatic layer 104 contains an organic binder, the content of the antistatic agent in the antistatic layer 104 is preferably 0.01 to 15.00 parts by mass per 100 parts by mass of the organic binder, from the viewpoint of exerting a sufficient antistatic effect.

[0121] 1.4.3. Friction Reducer The friction reducer is not particularly limited, but examples thereof include those exemplified as additives for the base layer.

[0122] The content of the friction reducing agent in the antistatic layer 104 is preferably 1.0 to 10.0% by mass, and more preferably 2.5 to 7.5% by mass, based on the total amount of the antistatic layer 104 .

[0123] When the antistatic layer 104 contains components other than the above-mentioned components, the other components are not particularly limited, and examples thereof include acrylic polymers such as (meth)acrylic acid ester polymers and acrylic graft polymers, urethane polymers, polyester polymers, epoxy polymers, polyvinyl chloride polymers, melamine polymers, polyimide polymers, and silicone polymers. The other components may be used alone or in combination of two or more. More specifically, an acrylic polymer may be an acrylic-silicone copolymer.

[0124] The content of other components in the antistatic layer 104 is not particularly limited, but is, for example, 0.1 to 10.0% by mass. The antistatic layer 104 may not contain other components.

[0125] The antistatic layer 104 may contain various additives such as a hardener, a plasticizer, an antioxidant, and a filler.

[0126] The thickness of the antistatic layer 104 is preferably 0.01 to 1 μm, more preferably 0.02 to 0.7 μm, from the viewpoint of exerting a sufficient antistatic effect.

[0127] 2. Method for Manufacturing Dicing Tape The method for manufacturing the dicing tape 100 of this embodiment is not particularly limited, but examples thereof include the following method.

[0128] The means for forming the substrate layer 101 is not particularly limited, but the above-mentioned various materials are mixed using a conventional melt kneader or various mixing devices (single-screw or twin-screw extruder, roll, Banbury mixer, various kneaders, etc.) so that the components are uniformly dispersed, and the mixture is formed into the substrate by a T-die method, a calendar method, or an inflation method. Preferably, the T-die method using an extruder with good thickness accuracy is used.

[0129] The means for forming the first adhesive layer 102 is not particularly limited, but may be such that the various materials described above are dissolved in a solvent such as an organic solvent to form a varnish, which is then applied to the base layer 101 by knife coating, roll coating, spray coating, gravure coating, bar coating, curtain coating, or the like, and the solvent is removed to form the first adhesive layer 102. The various materials described above in the form of a varnish may be applied to a molding film, the solvent may be removed to form the first adhesive layer 102, and the first adhesive layer 102 may be bonded to the base layer 101 to form the first adhesive layer 102 on the base layer 101.

[0130] The second adhesive layer 103 may be formed on the first adhesive layer 102 by the same method as the first adhesive layer 102, or a commercially available product as a die attach film may be attached to the first adhesive layer 102. When a commercially available product as a die attach film is not used, the means for forming the second adhesive layer 103 is not particularly limited, but the various materials described above may be dissolved in a solvent such as an organic solvent to form a varnish, which may be applied to the first adhesive layer 102, and the solvent may be removed to form the second adhesive layer 103. Alternatively, the second adhesive layer 103 may be formed on the first adhesive layer 102 by forming the second adhesive layer 103 on a molding film and then laminating this on the first adhesive layer 102.

[0131] The means for forming the antistatic layer 104 is not particularly limited, but the above-mentioned various materials may be dissolved in a solvent such as an organic solvent to form a varnish, which may then be applied to the back surface 101b of the base layer 101 to form the antistatic layer 104. Alternatively, the antistatic layer 104 may be formed on a molding film, which may then be laminated on the back surface 101b of the base layer 101 to form the antistatic layer 104 on the base layer 101.

[0132] The dicing tape of this embodiment may be stored or sold in a form in which a cylindrical second adhesive layer 103 is attached to a rectangular base material layer 101 and a first adhesive layer 102, as shown in Figure 11.

[0133] 3. Wafer Processing Method The wafer processing method using the dicing tape 100 of this embodiment includes a laminate fabrication step s201 of fabricating a laminate 500 in which the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300, inside which a modified portion 302 has been formed by laser dicing; a low-temperature expanding step s202 of expanding the wafer 300 into a die chip 303 by pushing up the expanding stage 402 from the exposed surface 100b side of the dicing tape 100 under conditions of 0° C. or less; and a pick-up step s206 of picking up the die chip 303 from the dicing tape 100.

[0134] The wafer 300 is not particularly limited, but may be, for example, a conventional general-purpose semiconductor wafer such as a silicon wafer, a gallium nitride wafer, a silicon carbide wafer, a sapphire wafer, etc. The non-element-formed surface 300b of the wafer 300 refers to the surface of both sides of the wafer 300 on which elements 301 such as circuits are not formed, and the element-formed surface 300a of the wafer 300 refers to the surface of both sides of the wafer 300 on which elements 301 such as circuits are formed.

[0135] Each step of the wafer processing method of this embodiment will be described in detail below.

[0136] 5(a) shows an example of a perspective view of the laminate fabrication step, and Fig. 5(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 5(a). The laminate fabrication step s201 is a step of fabricating a laminate 500 in which the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300, inside which a modified portion 302 has been formed by laser dicing.

[0137] The surface of the wafer 300 to which the dicing tape 100 is attached may be the non-element forming surface 300b or the element forming surface 300a. In the laminate fabrication step s201, it is preferable to attach the second adhesive layer 103 of the dicing tape 100 to the surface of the wafer 300.

[0138] The laminate fabrication step s201 includes at least a laser dicing step s2011 and a bonding step s2013, and may further include a back grinding step s2012. Each step will be described in detail below.

[0139] 2(a) shows an example of a perspective view of the laser dicing step s2011, and Fig. 2(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 2(a). The dashed line in Fig. 2 indicates the path of the laser irradiated area, and in the subsequent low-temperature expanding step, separation occurs at the dashed line portion to form a die chip 303.

[0140] 2(a) and 2(b), in the laser dicing step s2011, a laser is irradiated onto the wafer 300 to generate a modified region 302 inside the wafer 300. More specifically, in the laser dicing step, it is preferable to perform stealth dicing, in which a pulsed laser is focused inside the wafer 300 to form the modified region 302 inside the wafer 300. At this time, it is preferable that the modified region 302 does not appear on the surface of the wafer 300.

[0141] The laser source is not particularly limited, but examples thereof include ultraviolet lasers, visible light lasers, near-infrared lasers, and far-infrared lasers. More specifically, for example, an Nd:YAG laser can be used.

[0142] The surface of the wafer 300 irradiated with the laser may be the non-element-formed surface 300b or the element-formed surface 300a.

[0143] 2A and 2B, in the laser dicing step s2011, the wafer 300 may be irradiated with a laser while the wafer 300 is attached to the backgrinding tape 200. By performing a backgrinding step thereafter, the wafer 300 can be easily divided in the modified section 302. Note that the tape used in the laser dicing step s2011 is not limited to the backgrinding tape 200, and any known tape capable of fixing the wafer 300 can be used.

[0144] In the following, the laser dicing step s2011 may be performed before or after the back grinding step s2012. Also, the laser dicing step s2011 may be performed before or after the bonding step s2013.

[0145] 3(a) shows an example of a perspective view of the back-grinding step s2012, and Fig. 3(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 3(a). As shown in Figs. 3(a) and 3(b), in the back-grinding step s2012, the non-element forming surface 300b of the wafer 300 is ground to thin the wafer 300.

[0146] Specifically, with the backgrind tape 200 attached to the element-forming surface 300a from the viewpoint of protecting the element-forming surface 300a, the non-element-forming surface 300b of the wafer 300 is ground (backgrinded) to a position that reaches the modified portion 302 or a position close to the modified portion 302. This makes it easier to divide the wafer 300 into die chips 303 in the low-temperature expanding step s202.

[0147] The back grinding step s2012 may be performed before or after the laser dicing step s2011. Moreover, the back grinding step s2012 may be performed before or after the bonding step s2013 described later.

[0148] 4(a) shows an example of a perspective view of the bonding step s2013, and FIG. 4(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 4(a). As shown in FIGS. 4(a) and 4(b), in the bonding step s2013, the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300. At this time, the surface of the wafer 300 to which the dicing tape 100 is bonded may be either the non-element-forming surface 300b or the element-forming surface 300a.

[0149] Also, as shown in FIG. 4, the wafer 300 may not have a modified portion 302 inside, or, although not shown, the wafer 300 may already have a modified portion 302 generated inside by the laser dicing process s2011.

[0150] The bonding step s2013 of this embodiment may be performed by using a known device or manually, such as, but not limited to, a DFM2800 manufactured by Disco Corporation.

[0151] The above-described laser dicing step s2011, back grinding step s2012, and laminating step s2013 may be performed in any order. For example, after forming a modified portion by laser dicing (s2011), the non-element forming surface 300b may be back ground (s2012), and finally the dicing tape 100 may be laminated (s2013); after forming a modified portion by laser dicing (s2011), the dicing tape 100 may be laminated to the element forming surface 300a (s2013), and finally the non-element forming surface 300b may be back ground (s2012); after back grinding the non-element forming surface 300b (s2012), the modified portion may be formed by laser dicing (s2011), and finally the dicing tape 100 may be laminated (s2013); After back-grinding the element forming surface 300b (s2012), the dicing tape 100 may be attached (s2013), and finally the modified portion may be formed by laser dicing (s2011); after attaching the dicing tape 100 to the element forming surface 300a (s2013), and the modified portion may be formed by laser dicing (s2011), finally the non-element forming surface 300b may be back-ground (s2012); or after attaching the dicing tape 100 to the element forming surface 300a (s2013), the non-element forming surface 300b may be back-ground (s2012), and finally the modified portion may be formed by laser dicing (s2011).

[0152] Among these, from the viewpoint of improving work efficiency due to the fact that each step can be performed successively, it is preferable to perform the steps in the order of s2011, s2012, and s2013.

[0153] Furthermore, if the back grinding step s2012 is not performed, steps s2011 and s2013 may be performed in that order, or steps s2013 and s2011 may be performed in that order.

[0154] 2 to 4, when steps s2011, s2012, and s2013 are performed in this order, the back-grinding tape 200 may be attached to the element-forming surface 300a of the wafer 300, and the laser dicing step s2011 in which a laser is irradiated from the non-element-forming surface 300b side of the wafer 300 and the back-grinding step s2012 may be performed consecutively, and then the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 may be attached to the non-element-forming surface 300b of the wafer 300, and the back-grinding tape 200 may be peeled off. Alternatively, the back-grinding tape 200 may be peeled off first, and then the dicing tape 100 may be attached.

[0155] Alternatively, after performing the laser dicing step s2011 in which a laser is irradiated from the element forming surface 300a side of the wafer 300, the back grinding step s2012 may be performed by laminating the back grinding tape 200 to the element forming surface 300a of the wafer 300, and then the first adhesive layer or the second adhesive layer of the dicing tape 100 may be laminated to the non-element forming surface 300b of the wafer 300, and the back grinding tape 200 may be peeled off. Alternatively, the back grinding tape 200 may be peeled off first, and then the dicing tape 100 may be laminated.

[0156] 3.2 Low-Temperature Expanding Step Fig. 6(a) shows an example of a perspective view of the low-temperature expanding step, and Fig. 6(b) shows an example of a cross-sectional view taken along line AA' in Fig. 6(a).

[0157] In the low-temperature expanding step s202, the expanding stage 402 is pushed up from the exposed surface 100b side of the dicing tape 100 under conditions of 0° C. or below. At this time, tension is applied to the dicing tape 100 between the ring frame 401 and the wafer 300, causing the dicing tape 100 to expand in the planar direction. Then, stress is applied outward from the center of the wafer 300, and the wafer 300 adhered to the dicing tape 100 is divided at the modified portions 302, etc., to form individual die chips 303.

[0158] In this embodiment, the exposed surface 100b of the dicing tape 100 refers to the surface of the dicing tape 100 that is exposed because it is not in contact with the wafer 300. Specifically, for example, it refers to the surface of the base material layer 101 that is not in contact with the first adhesive layer 102, or, if the dicing tape 100 has an antistatic layer 104, the surface of the antistatic layer 104 that is not in contact with the base material layer 101.

[0159] If the frictional force between the expanding stage 402 and the dicing tape is too large, when the expanding stage 402 is pushed up, the portions of the dicing tape that are not in contact with the frame 401 and the expanding stage 402 will preferentially expand, and the stress will not be sufficiently transmitted from the center of the wafer 300 to the wafer 300. As a result, the wafer 300 will tend to be insufficiently divided. In this regard, the dicing tape 100 of this embodiment has a dynamic friction coefficient within an appropriate range in a low-temperature environment with respect to SUS304, a typical material of the expanding stage 402. Therefore, the dynamic frictional force between the expanding stage 402 and the dicing tape 100 will be within an appropriate range, the wafer 300 will be sufficiently divided, and the wafer 300 will tend to be excellent in divisibility at low temperatures.

[0160] The low-temperature expanding process s202 aims to divide the wafer 300 to obtain die chips 303, and is preferably carried out at 0°C or below to improve the divisibility of the wafer 300 and the second adhesive layer 103, and more preferably at -25 to 0°C.

[0161] 7(a) shows an example of a perspective view of the room-temperature expanding step, and Fig. 7(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 7(a). After the low-temperature expanding step s202, the wafer processing method of this embodiment preferably further includes a room-temperature expanding step s203 in which the expanding stage 402 is pushed up from the exposed surface 100b side of the dicing tape 100 at a temperature of 5°C or higher to expand the dicing tape 100.

[0162] The room-temperature expanding step s203 can be performed in the same manner as the low-temperature expanding step s202, except that the expanding environment is 5° C. or higher. The expanding device 400 in the low-temperature expanding step s202 and the expanding device 400 in the room-temperature expanding step s203 may be the same or different. When the low-temperature expanding step s202 and the room-temperature expanding step s203 are performed using the same expanding device 400, the frame 401 and the expanding stage 402 in the low-temperature expanding step s202 and the frame 401 and the expanding stage 402 in the room-temperature expanding step s203 may be the same or different.

[0163] One of the purposes of the room-temperature expanding step s203 is to further increase the spacing between the die tips 303 produced in the low-temperature expanding step s202, and the expanding stage 402 is pushed up by an amount greater than the amount pushed up in the low-temperature expanding step s202. In order to improve the extensibility of the dicing tape 100 and further increase the spacing between the die tips 303, the room-temperature expanding step s203 is preferably performed at 5°C or higher, more preferably at 5 to 40°C, and even more preferably at 10 to 30°C.

[0164] 8(a) shows an example of a perspective view of the heat shrinking step, and Fig. 8(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 8(a). The wafer processing method of this embodiment preferably further includes a heat shrinking step s204, after the low-temperature expanding step s202, in which a portion of the dicing tape 100 that is not in contact with the wafer 300 is heated to shrink the base layer 101 in the heated portion.

[0165] More specifically, a restoring force is generated in the dicing tape 100 stretched in the low-temperature expanding step s202 and the room-temperature expanding step s203, so when the expanding stage 402 is lowered to reduce the tension, the die chip 303 also moves toward the center of the dicing tape 100 in response to the restoring force. Therefore, by performing the heat shrinking step s204 in the area where tension (restoring force) is applied between the ring frame 401 and the wafer 300, a constant tension is applied to the die chip 303 even after the expanding stage 402 is lowered.

[0166] The heat shrinking step s204 may be performed under the condition where the greatest tension is applied in the room temperature expanding step. In the heat shrinking step s204, it is preferable that not only the base material layer 101 but also the first adhesive layer 102 shrink, and it is preferable that the dicing tape 100 shrinks.

[0167] Figures 8(a) and (b) illustrate the heat shrink process s204 performed when the dicing tape 100 is present on the expanding stage 402, but the heat shrink process s204 may also be performed when the dicing tape 100 is present on any base other than on the expanding stage 402.

[0168] 9(a) shows an example of a perspective view of the irradiation step, and FIG. 9(b) shows an example of a cross-sectional view taken along line A-A' in FIG. 9(a). The wafer processing method of this embodiment preferably further includes an irradiation step s205 of irradiating the first adhesive layer 102 with ultraviolet light after the low-temperature expanding step s202.

[0169] In the irradiation step s205, the first adhesive layer 102 is irradiated with ultraviolet light to harden the first adhesive layer 102 and reduce its adhesive strength to the second adhesive layer 103 or the wafer 300, thereby making it easier to pick up the die chip 303 from the dicing tape 100. When the dicing tape 100 has the second adhesive layer 103, the adhesive strength of the second adhesive layer 103 to the first adhesive layer 102 is reduced while its adhesive strength to the die chip 303 is maintained.

[0170] The ultraviolet light may be applied from the element forming surface 300a side of the wafer 300, or from the non-element forming surface 300b side of the wafer 300. The ultraviolet light may be applied from the surface of the wafer 300 that is not in contact with the dicing tape 100, or from the surface of the wafer 300 that is in contact with the dicing tape 100.

[0171] When ultraviolet light is irradiated from the surface of the wafer 300 that is not in contact with the dicing tape 100, the dicing tape 100 may or may not be placed on any pedestal.

[0172] When manually irradiating with ultraviolet light, known ultraviolet light sources such as a mercury lamp and an excimer lamp can be used as the ultraviolet light source.

[0173] 10(a) shows an example of a perspective view of the pick-up step, and Fig. 10(b) shows an example of a cross-sectional view taken along line A-A' in Fig. 10(a). The wafer processing method of this embodiment includes a pick-up step s206 in which the die chip 303 is picked up from the dicing tape 100.

[0174] When the dicing tape 100 has the second adhesive layer 103, it is preferable to peel the second adhesive layer 103 from the first adhesive layer 102 and pick up the die chip 303 with the second adhesive layer 103 attached from the dicing tape 100, and it is more preferable to peel the second adhesive layer 103 from the first adhesive layer 102 after the irradiation step s205 and pick up the die chip 303 with the second adhesive layer 103 attached from the dicing tape 100. When the dicing tape 100 does not have the second adhesive layer 103, only the die chip 303 is picked up.

[0175] In the pick-up step s206, although not particularly limited, for example, as shown in FIG. 10, the die tip 303 can be pushed up by a push-up needle N and picked up by suction with a suction collet C.

[0176] The order in which the above steps are performed is not particularly limited. Below, examples of the wafer processing method of this embodiment in which the order in which the steps are performed is changed will be given.

[0177] Among these, it is preferable to perform the steps s201, s202, s203, s204, s205, and s206 in this order.

[0178] The wafer processing method of the present embodiment may include other steps in addition to the steps described above, as necessary. The above illustrates the laminate fabrication step of fabricating the laminate 500 in which the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300 in which the modified region 302 has been formed by laser dicing. However, other aspects of the laminate fabrication step may include a laminate fabrication step of fabricating the laminate 500 in which the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300 in which division grooves have been formed by laser ablation, or a laminate fabrication step of fabricating the laminate 500 in which the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 is bonded to the surface of the wafer 300 in which division grooves have been formed by blade dicing.

[0179] Although the above example illustrates a wafer processing method, the dicing tape 100 of this embodiment may be used to process an adherend such as a semiconductor package instead of a wafer.

[0180] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples. Unless otherwise specified, the experiments were carried out at 25°C and 1 atmosphere.

[0181] Example 1 An ionomer resin (manufactured by Mitsui-Dow Polychemicals, product name "Himilan 1855") was molded into a sheet with a thickness of 80 μm to obtain a substrate layer.

[0182] Next, 67 mol % of 2-ethylhexyl acrylate and 33 mol % of 2-hydroxyethyl acrylate were copolymerized, and 80% of the hydroxyl groups of the resulting polymer were reacted with 2-methacryloyloxyethyl isocyanate to obtain a base polymer. The resulting base polymer had polymerizable double bonds derived from 2-methacryloyloxyethyl isocyanate in its side chains as a result of the reaction between the hydroxyl groups of the polymer and the isocyanate groups of 2-methacryloyloxyethyl isocyanate.

[0183] Then, 100 parts by mass of the base polymer obtained as described above, 3 parts by mass of trimethylolpropane-adducted tolylene diisocyanate (manufactured by Mitsui Chemicals, Inc.) as a curing agent, and 4 parts by mass of TPO-H (manufactured by BASF) were mixed to prepare a composition for adhesive layer.

[0184] Then, the adhesive layer composition was applied onto the base layer as described above to form a first adhesive layer having a thickness of 10 μm, thereby obtaining the dicing tape of Example 1.

[0185] Example 2 An ionomer resin (manufactured by Mitsui-Dow Polychemicals, product name "Himilan 1650") was molded into a sheet having a thickness of 80 μm to obtain a substrate layer. A dicing tape of Example 2 was obtained in the same manner as Example 1, except that the obtained substrate layer was used.

[0186] Example 3: 90 parts by mass of an ionomer resin (manufactured by Mitsui-Dow Polychemicals, product name "Himilan 1706") and 10 parts by mass of an olefin-based elastomer were mixed and molded into a sheet with a thickness of 80 μm to obtain a substrate layer. A dicing tape of Example 3 was obtained in the same manner as Example 1, except that the obtained substrate layer was used.

[0187] Example 4 A dicing tape of Example 4 was obtained in the same manner as in Example 3, except that 100 parts by mass of an antistatic agent, 1SX-1055F (quaternary ammonium salt-type acrylic polymer: product name, manufactured by Taisei Fine Chemical Co., Ltd.), was applied to the surface of the base material layer opposite to the surface on which the first adhesive layer was formed to form an antistatic layer having a thickness of 0.5 μm.

[0188] Example 5 A mixture for an antistatic layer was obtained by mixing 100 parts by mass of 1SX-1055F (a quaternary ammonium salt-type acrylic polymer: product name, manufactured by Taisei Fine Chemical Co., Ltd.) as an antistatic agent and 5 parts by mass of KP-611 (a silicone-based graft copolymer: product name, manufactured by Shin-Etsu Chemical Co., Ltd.) as a friction reducer. The mixture for an antistatic layer was then applied to the surface of the base layer opposite to the surface on which the first adhesive layer was formed, to form an antistatic layer having a thickness of 0.5 μm. A dicing tape of Example 5 was obtained in the same manner as in Example 3, except that the mixture for an antistatic layer was applied to the surface of the base layer opposite to the surface on which the first adhesive layer was formed, to form an antistatic layer having a thickness of 0.5 μm.

[0189] Comparative Example 1 A dicing tape of Comparative Example 1 was obtained in the same manner as in Example 1, except that a polyethylene terephthalate (PET) film (thickness: 80 μm) was used as the base layer instead of the base layer of Example 1.

[0190] Comparative Example 2 A dicing tape of Comparative Example 2 was obtained in the same manner as in Example 1, except that an ethylene vinyl acetate (EVA) film (thickness: 80 μm) was used as the base layer instead of the base layer of Example 1.

[0191] Comparative Example 3 A dicing tape of Comparative Example 3 was obtained in the same manner as in Example 1, except that a polyvinyl chloride (PVC) film (thickness: 80 μm) was used as the base layer instead of the base layer of Example 1.

[0192] [Dynamic Friction Coefficient and Static Friction Coefficient] The coefficient of friction was measured in accordance with JIS K7125. Specifically, bright annealed (BA) finished SUS304 was pressed against the exposed surface of the base layer opposite the first adhesive layer with a load of 4.3 N (thread weight 200 g) while moving at a speed of 100 mm / min, and the dynamic friction coefficient and static friction coefficient were measured. The measurement temperature was 0°C, and only in Example 5, the dynamic friction coefficient and static friction coefficient were also measured under conditions of -15°C.

[0193] [Tensile storage modulus] The tensile storage modulus of the base layer was measured in accordance with the storage modulus in the tension mode described in JIS K7244-1:1998. Specifically, first, a base layer sheet was kept in a thermo-hygrostat at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours. Using the obtained base layer sheet as a sample, dynamic viscoelasticity measurement was carried out under normal atmospheric conditions. A dynamic viscoelasticity measuring device named "Rheomeric Series RSA III" (manufactured by TA Instruments) was used. From the measurement results, the tensile storage modulus at 0°C and -15°C was obtained. (Measurement conditions) Measuring device: Rheomeric Series III (manufactured by TA Instruments) Environment: Nitrogen atmosphere Sample: 50 mm length x 5 mm width x 80 μm thickness Test length: 10 mm Pretreatment: Hold in an atmosphere at a temperature of 23°C and a relative humidity of 50% for 40 hours Test mode: Tension in a direction parallel to the surface of the substrate layer sheet Frequency: 10 Hz Temperature range: -30°C to 10°C Heating rate: 3°C / min Strain range: 0.07% Measurement interval: 1 Point / °C

[0194] [Evaluation] (Division ratio) Using an expanding device, one wafer attached to the dicing tape of each example was divided into die chips by low-temperature expansion at 0° C., and then the width of the die chip was expanded by room-temperature expansion at 23° C. In addition, for Example 5, the width of the die chip was also expanded by low-temperature expansion at −15° C. and then room-temperature expansion at 23° C.

[0195] The ratio of the number of die chips that could actually be obtained to the ideal number of die chips that could be obtained from one wafer (division rate (%): number of die chips that could actually be obtained / ideal number of die chips) was calculated. Note that die chips that were not of an ideal shape, such as those with chipped corners, burrs, or meandering edges, were not included in the number of die chips that could actually be obtained.

[0196] (Kerf Width) As with the above division ratio, using an expanding device, one wafer attached to the dicing tape of each example was low-temperature expanded at 0° C. to divide it into die chips, and then the kerf width of the die chip was widened by room-temperature expansion at 23° C. Note that for Example 5, low-temperature expansion at −15° C. and then room-temperature expansion at 23° C. were also performed to widen the width of the die chip.

[0197] After room temperature expansion, the kerf width, which is the distance (μm) between the die tips, was measured and the average value was calculated.

[0198]

[0199] In Comparative Example 1, the elastic modulus of the base material layer was too high, and the material could hardly be expanded.

[0200] In addition, a second adhesive layer was laminated on the first adhesive layer of the dicing tape obtained in Example 5. The division ratio and kerf width were evaluated as described above, and results were comparable to those of Example 5 in Table 1. This confirmed the effects of the present invention even in an embodiment in which a second adhesive layer, which serves as a pressure-sensitive adhesive layer for a DAF film, was laminated on the first adhesive layer. Furthermore, when picking up the die chip, ultraviolet light was irradiated onto the first adhesive layer, which allowed the first adhesive layer and the second adhesive layer to be easily peeled off after ultraviolet light irradiation, and pickup was possible with the second adhesive layer still attached to the die chip.

[0201] The second adhesive layer was prepared as follows: 55 parts by mass of YDCN-703 epoxy resin (manufactured by Tohto Kasei Co., Ltd., cresol novolac epoxy resin, epoxy equivalent 210, molecular weight 1200, softening point 80°C), 45 parts by mass of Milex XLC-LL phenolic resin (manufactured by Mitsui Chemicals, Inc., hydroxyl equivalent 175, water absorption 1.8%, heat mass loss rate at 350°C 4%), 1.7 parts by mass of NUCA-189 silane coupling agent (manufactured by Nippon Unicar Co., Ltd., γ-mercaptopropyltrimethoxysilane), Cyclohexanone was added to 3.2 parts by mass of NUCA-1160 (manufactured by Nippon Unicar Co., Ltd., γ-ureidopropyltriethoxysilane) and 32 parts by mass of filler Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd., a silica filler in which the silica surface is coated with dimethyldichlorosilane and hydrolyzed in a reactor at 400°C to surface-modify with organic groups such as methyl groups, average particle size 0.016 μm), and the mixture was stirred and mixed, and further kneaded using a bead mill for 90 minutes to obtain a mixture. To the resulting mixture, 280 parts by mass of acrylic rubber HTR-860P-3 (manufactured by Nagase ChemteX Corporation, weight average molecular weight 800,000, acrylic rubber containing 3% by mass of glycidyl acrylate or glycidyl methacrylate) and 0.5 parts by mass of curing accelerator Curesol 2PZ-CN (manufactured by Shikoku Chemicals Corporation, 1-cyanoethyl-2-phenylimidazole) were added, stirred and mixed, and vacuum degassed to obtain a varnish for the second adhesive layer. The resulting varnish was applied to the first adhesive layer of the dicing tape obtained in Example 5 and heated and dried at 140°C for 5 minutes to form a second adhesive layer with a thickness of 10 μm.

[0202] DESCRIPTION OF SYMBOLS 100... dicing tape, 100b... exposed surface, 101... base layer, 101a... front surface, 101b... back surface, 102... first adhesive layer, 103... second adhesive layer, 104... antistatic layer, 200... back grinding tape, 300... wafer, 300a... element forming surface, 300b... non-element forming surface, 301... element, 302... modified portion, 303... die chip, 400... expansion device, 401... frame, 402... expansion stage, 500... laminate, H... heat source, L... laser source, U... ultraviolet light source, C... suction collet, N... push-up needle, P... polishing machine

Claims

1. A laminated sheet having a base layer having a front surface and a back surface, and a first adhesive layer laminated on the front surface of the base layer, wherein the tensile storage modulus of the base layer at 0°C is 1.0 x 10 ８ ~9.9 x 10 ８ Pa, and the dynamic friction coefficient of the exposed surface on the back side of the base layer against SUS304 at 0°C is 0.1 to 1.

5.

2. The dicing tape according to claim 1, wherein the static friction coefficient of the exposed surface of the base layer against SUS304 at 0°C is 0.1 to 1.

5.

3. The dicing tape according to claim 1, wherein the base layer has an antistatic agent or an antistatic layer on the back surface side.

4. The dicing tape according to claim 1, further comprising a second adhesive layer on the first adhesive layer.

5. A wafer processing method comprising: a laminate fabrication step of fabricating a laminate in which the first adhesive layer or the second adhesive layer of the dicing tape according to any one of claims 1 to 4 is bonded to the surface of a wafer in which a modified portion has been formed inside by laser dicing; a low-temperature expansion step of expanding the wafer into die chips by pushing up an expansion stage from the exposed surface side of the dicing tape under conditions of 0°C or below; and a pick-up step of picking up the die chips from the dicing tape.

6. The wafer processing method according to claim 5, further comprising an irradiation step of irradiating the first adhesive layer with ultraviolet light after the low-temperature expanding step.

7. A wafer processing method as described in claim 6, wherein, when the dicing tape has the second adhesive layer, in the pick-up process, the second adhesive layer is peeled off from the first adhesive layer after the ultraviolet irradiation, and the die chip with the second adhesive layer attached is picked up from the dicing tape.

8. The wafer processing method according to claim 5, wherein the surface of the wafer is a non-device forming surface.

9. The wafer processing method according to claim 5, wherein the surface of the wafer is a device formation surface.

10. The wafer processing method according to claim 5, further comprising a room temperature expanding step in which, after the low temperature expanding step, an expanding stage is pushed up from the exposed surface side of the dicing tape to expand it under conditions of 5°C or higher.

11. The wafer processing method according to claim 5, further comprising a heat shrinking step in which, after the low-temperature expanding step, a portion of the dicing tape that is not in contact with the wafer is heated to shrink the base layer in the heated portion.

Images