Dicing tape and wafer processing method

Abstract

To provide a dicing tape having good wafer separation properties during low-temperature expansion, and a wafer processing method using the same.SOLUTION: The dicing tape has a substrate layer having a front surface and a back surface, and a first adhesive layer laminated on the front surface of the substrate layer. The thickness of the first adhesive layer is 3 to 20 μm. The shear storage modulus of the first adhesive layer at 0°C is 1.0×105 to 9.9×105 Pa.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[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 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). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-009324 Summary of the Invention [Problem to be solved by the invention]

[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 into chips. However, the method for dividing a wafer into chips is not limited to this. For example, methods such as stealth dicing can be used, in which modified areas are formed and the wafer is divided at the modified areas using a force that spreads in the surface direction of the expander, or laser ablation dicing can be used, in which dividing grooves are formed and the wafer is divided at the dividing grooves using a force that spreads in the surface direction of the expander. Another possible method is to form dividing grooves on the wafer surface by blade dicing, and then divide the wafer at the dividing grooves using a force that spreads in the surface direction of the expander.

[0006] Thus, when dicing a wafer by the force of the expander spreading in the plane direction, 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 the expander spreading in the plane direction.

[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. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by making the first adhesive layer of the dicing tape have a predetermined thickness and shear storage modulus, which has led to the completion of the present invention.

[0009] That is, the present invention is as follows. [1] a substrate layer having a front surface and a back surface; a first adhesive layer laminated on the surface of the base material layer, The thickness of the first adhesive layer is 3 to 20 μm, The shear storage modulus of the first adhesive layer at 0°C is 1.0 × 10 5 ~9.9×10 5 Pa, Dicing tape. [2] The substrate layer has an antistatic agent or an antistatic layer on the back surface side. [1] The dicing tape according to [1]. [3] A second adhesive layer is provided on the first adhesive layer. The dicing tape according to [1] or [2]. [4] The adhesive strength of the first adhesive layer to SUS304 at 23°C is 0.50 N / 20 mm or more. The dicing tape according to any one of [1] to [3]. [5] a laminate preparation step of preparing 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 in which a modified portion has been formed by laser dicing; a low-temperature expanding step of expanding the wafer into a die chip by pushing up an expanding stage from the exposed surface side of the dicing tape under a condition of 0°C or less; a pick-up step of picking up the die chip from the dicing tape. Wafer processing method. [6] The method further includes an irradiation step of irradiating the first adhesive layer with ultraviolet light after the low-temperature expanding step. [5] The wafer processing method according to [5]. [7] When the dicing tape has the second adhesive layer, In the pick-up step, peeling the second adhesive layer from the first adhesive layer after the ultraviolet irradiation, and picking up the die chip with the second adhesive layer attached thereto from the dicing tape; [6] The wafer processing method according to [6]. [8] the surface of the wafer is a non-device-forming surface; The wafer processing method according to any one of [5] to [7]. [9] the surface of the wafer is an element formation surface; The wafer processing method according to any one of [5] to [7].

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

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

[10] . [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0011] [Figure 1] 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 AA' in FIG. 1(a). [Figure 2] 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 AA' in FIG. 2(a). [Figure 3] 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 AA' in FIG. 3(a). [Figure 4] FIG. 4(a) shows an example of a perspective view of the bonding step, and FIG. 4(b) shows an example of a cross-sectional view taken along line AA' in FIG. 4(a). [Figure 5] FIG. 5(a) shows an example of a perspective view of the laminate manufacturing process, and FIG. 5(b) shows an example of a cross-sectional view taken along line AA' in FIG. 5(a). [Figure 6] 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). [Figure 7] FIG. 7(a) shows an example of a perspective view of the cold-expanding step, and FIG. 7(b) shows an example of a cross-sectional view taken along line AA' in FIG. 7(a). [Figure 8] FIG. 8(a) shows an example of a perspective view of the heat shrink process, and FIG. 8(b) shows an example of a cross-sectional view taken along line AA' in FIG. 8(a). [Figure 9] 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 AA' in FIG. 9(a). [Figure 10] FIG. 10(a) shows an example of a perspective view of the pick-up process, and FIG. 10(b) shows an example of a cross-sectional view taken along line AA' in FIG. 10(a). [Figure 11] FIG. 2 shows an example of a perspective view of a wound body of the dicing tape of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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, but the present invention is not limited to this, 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 will be 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 the present embodiment includes 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, the first adhesive layer having a thickness of 3 to 20 μm, and a shear storage modulus of the first adhesive layer at 0° C. of 1.0×10 5 ~9.9×10 5 It is Pa.

[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 layer 101 and a first adhesive layer 102 laminated on the front surface 101a of the base 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 layer 101.

[0015] The second adhesive layer 103 and the antistatic layer 104 can be formed in any manner, and in addition to the embodiments shown in Figures 1(a) and 1(b), there may be 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. Furthermore, an intermediate layer may be provided between each layer as needed from the viewpoint of inter-layer adhesion and adhesiveness.

[0016] Next, as a prerequisite 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] As shown in FIGS. 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, in order to suppress the elongation of each adhesive layer and increase the tensile stress to facilitate division, the expansion may be performed at a relatively low temperature such as 0°C or -15 to 0°C. This process is referred to as the "low-temperature expanding process."

[0018] In this way, in order to divide the wafer 303 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 first adhesive layer 102.

[0019] From this perspective, in this embodiment, the shear storage modulus of the first adhesive layer 102 at low temperatures is specified. This makes it easier for the tension (restoring force) applied to the base layer 101 of the dicing tape 100 to be transmitted to the wafer 300 via the first adhesive layer 102 during the low-temperature expanding process. This improves the transmittance 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] From the same viewpoint, in this embodiment, the thickness of the first adhesive layer 102 is specified. This allows the tension (restoring force) applied to the base layer 101 of the dicing tape 100 in the low-temperature expanding step to be easily transmitted to the wafer 300 without being attenuated by the first adhesive layer 102. As a result, the transmittance of external force to the wafer 300 is improved. This prevents defective division, such as division at the modified portion 302, and further improves division.

[0021] Each component of the dicing tape 100 of this embodiment will be described in detail below.

[0022] 1.1. Base material layer The dicing tape 100 of this embodiment has a base layer 101 having a front surface 101a and a back surface 101b. The base layer 101 preferably contains a resin. The resin is not particularly limited, but examples thereof 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 layer 101 may be a mixture, copolymer, or laminate of one of these resins with another.

[0023] 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.

[0024] 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.

[0025] The polyolefin ionomer is not particularly limited, but examples thereof include ethylene-methacrylate copolymer, ethylene-acrylate copolymer, and ethylene-methacrylate-acrylate copolymer.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The metal ions constituting the salt of the ionomer resin are not particularly limited, but 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 ionic functional group in the polymer and the valence of the metal ions.

[0030] 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.

[0031] 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.

[0032] 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, and antistatic agents. The additives may be used alone or in combination.

[0033] The content of the additive with respect to the entire base material layer 101 is preferably 0.1 to 10.0 mass %, 0.5 to 5.0 mass %, or 1.0 to 2.5 mass %.

[0034] The antistatic agent is not particularly limited, but examples thereof include carbon nanotubes, metal oxides, polythiophenes, polyanilines, polypyrroles, dimethylaminoethyl (meth)acrylate quaternary chlorides, diethylaminoethyl (meth)acrylate quaternary chlorides, methylethylaminoethyl (meth)acrylate quaternary chlorides, p-dimethylaminostyrene quaternary chlorides, p-diethylaminostyrene quaternary chlorides, and acrylic polymers having quaternary ammonium salts in their side chains. The antistatic agents may be used alone or in combination of two or more. More specifically, the antistatic agent may include an acrylic polymer containing methyl methacrylate as the main component and 2-dimethylaminoethyl methacrylate and 2-hydroxyethyl methacrylate as structural units.

[0035] 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.

[0036] The substrate layer 101 may be a single layer or multi-layer structure comprising the materials mentioned above.

[0037] 1.2.First adhesive layer The dicing tape 100 of this embodiment has a first adhesive layer 102 laminated on the surface of a 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 1.2.1. Base polymer The base polymer having a polymerizable carbon-carbon double bond is a component that constitutes 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, and the adhesive strength decreases.

[0042] The base polymer is not particularly limited, and 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, and examples thereof include linear, branched, or crosslinked shapes. Among these, crosslinked shapes are preferred. By using such a base polymer, the cohesive force of the first adhesive layer 102 is improved, which further improves adhesion to the wafer and tends to further reduce contamination. 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.

[0043] The (meth)acrylic acid ester monomer constituting the (meth)acrylic acid ester 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.

[0044] Furthermore, 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. Examples of suitable monomers include hydroxyl group-containing monomers such as styrene sulfonic acid, allyl sulfonic 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-hydroxyethyl acryloyl phosphate. These other monomers may be used singly or in combination of two or more.

[0045] Among these, a (meth)acrylic acid ester copolymer containing an alkyl (meth)acrylate and a carboxyl group-containing monomer, and a (meth)acrylic acid ester copolymer containing an alkyl (meth)acrylate and a hydroxyl group-containing monomer are preferred.

[0046] 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.

[0047] 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.

[0048] Furthermore, 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.

[0049] 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.

[0050] 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, UV irradiation sufficiently promotes the crosslinking reaction of the polymerizable double bonds of the base polymer, resulting in a reduction in the contact area with the wafer due to cure shrinkage, thereby sufficiently reducing adhesive strength. This means that peeling is facilitated, further improving pickup performance. Furthermore, monomer components that were not polymerized during polymer component synthesis may be able to react with double bonds in the polymer component side chains upon UV irradiation, which also helps prevent adhesive residue.

[0051] 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.

[0052] Because the base polymer has hydroxyl groups, when a curing agent, which will be described later, is blended, further cross-linking between multiple polymers can occur 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 base material layer 101 and the first adhesive layer 102 is also improved, which tends to suppress cohesive failure and anchor failure and result in more stable adhesive properties.

[0053] Of 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.

[0054] 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.

[0055] 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.

[0056] The content of the photopolymerization initiator 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 photopolymerization initiator is within the above range, contamination tends to be further suppressed.

[0057] Additives The first adhesive layer 102 may contain additives such as a curing agent, a tackifier, a crosslinking retarder, and an antioxidant.

[0058] 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.

[0059] The isocyanate compound is not particularly limited, and examples thereof include compounds having a group that reacts with the hydroxyl group or carboxyl group of the base polymer. More specific examples include tolylene diisocyanates such as trimethylolpropane-added 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.

[0060] 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 base material layer and the first adhesive layer 102 also improves, which tends to result in more stable adhesive properties.

[0061] The content of the curing agent is preferably 0.1 to 10.0 parts by mass, more preferably 0.2 to 9.0 parts by mass, and even more preferably 0.3 to 8.0 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 due to 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.

[0062] The content of the curing agent is preferably 0.1 to 10.0 mass %, 0.2 to 9.0 mass %, or 0.3 to 8.0 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.

[0063] 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 mass%, 0.2 to 1.5 mass%, or 0.3 to 1.0 mass% relative to the total mass of the first adhesive layer 102.

[0064] 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. The content of the crosslinking retarder is preferably 0.1 to 2.0 mass%, 0.2 to 1.5 mass%, or 0.3 to 1.0 mass% relative to the total mass of the first adhesive layer 102.

[0065] 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. 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 %.

[0066] The thickness of the first adhesive layer 102 is 3 to 20 μm, preferably 3 to 19 μm, 3 to 18 μm, or 3 to 17 μm. When the thickness of the first adhesive layer 102 is within the above range, the divisibility of the wafer 300 tends to be further improved.

[0067] The shear storage modulus of the first adhesive layer 102 at 0°C is 1.0×10 5 ~9.9×10 5 Pa, preferably 2.0 x 10 5 ~9.0×10 5 Pa, 2.5 x 10 5 ~8.5×10 5 Pa, 3.0 x 10 5 ~8.0×10 5 Pa, 4.0 x 10 5 ~7.5×10 5 Pa, 4.5 x 10 5 ~7.0×10 5 Pa. When the shear storage modulus at 0° C. is within the above range, the divisibility of the wafer 300 tends to be further improved.

[0068] The shear storage modulus of the first adhesive layer 102 at −15° C. is preferably 1.0×10 5 ~9.9×10 5 Pa, 2.5 x 10 5 ~9.5×10 5 Pa, 3.5 x 10 5 ~8.5×10 5 Pa, 4.5 x 10 5 ~7.5×10 5 It is Pa.

[0069] The shear storage modulus at temperatures between −15° C. and 0° C. can be adjusted by the type and composition of the resin that constitutes the first adhesive layer 102 .

[0070] 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 conceivable 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 wafers is improved if the shear storage modulus measured based on -15 to 0°C satisfies a predetermined range. Unless otherwise specified, in this specification, the measurement temperature for shear storage modulus is -15 to 0°C.

[0071] In this embodiment, the first adhesive layer 102 is preferably cut at a cross section parallel to the thickness direction in the low-temperature expanding step. From this viewpoint, the deformation mode when measuring the storage modulus of the first adhesive layer 102 is set to shear.

[0072] The shear storage modulus is measured in accordance with the storage modulus in shear mode described in JIS K7244-1:1998, except that the temperature condition is -15°C to 0°C.

[0073] The adhesive strength of first adhesive layer 102 to SUS304 at 23° C. is preferably 0.50 N / 20 mm or more, 0.50 to 3.50 N / 20 mm, 0.60 to 3.00 N / 20 mm, 0.70 to 2.75 N / 20 mm, or 0.80 to 2.50 N / 20 mm. When the adhesive strength is within the above range, a larger amount of expansion is possible during room temperature expansion, and as a result, the divisibility of wafer 300 tends to improve.

[0074] The adhesive strength of the first adhesive layer 102 to SUS304 at 23° C. can be adjusted by the type and composition of the resin that constitutes the first adhesive layer 102.

[0075] In this embodiment, 23°C is used as a reference value for the room temperature in room-temperature expansion. In this regard, it is expected that room-temperature expansion may be performed at a temperature higher or lower than 23°C depending on the specifications of the expanding equipment. However, even if the room temperature during actual room-temperature expansion is not 23°C but is higher or lower than this, it can be said that the wafer divisibility is improved if the adhesive strength measured with 23°C as the reference falls within a predetermined range. Unless otherwise specified, in this specification, the temperature for measuring the adhesive strength is 23°C.

[0076] The adhesive strength is measured in accordance with the peel adhesive strength test method described in Part 1: 90° peel of JIS K6854-1:1999, except that the temperature condition is 23°C.

[0077] 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 to this, peeling may occur at the interface between the second adhesive layer 103 and the first adhesive layer 102 in the pick-up step, 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 the die chip 303 is mounted on a substrate.

[0078] The second adhesive layer 103 may be disposed only on the portion of the dicing tape 100 where the wafer 300 is disposed, or the second adhesive layer 103 may be formed in a portion other than the above-mentioned portion.

[0079] From this perspective, 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.

[0080] Such second adhesive layer 103 may be made from various materials, or a commercially available die attach film may be used. When making second adhesive layer 102, 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.

[0081] 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.

[0082] 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 %.

[0083] 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.

[0084] The content of the polyurethane resin relative to the total amount of resin in the second adhesive layer 103 is preferably 3 to 35 mass %, and more preferably 5 to 30 mass %.

[0085] 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.

[0086] 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 %.

[0087] 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.

[0088] 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 %.

[0089] 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.

[0090] The content of the silane coupling agent relative to the total amount of resin in the second adhesive layer 103 is preferably 1 to 10 mass %, and more preferably 2 to 8 mass %.

[0091] 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.

[0092] The content of the curing agent relative to the total amount of resin in the second adhesive layer 103 is preferably 3 to 30 mass %, and more preferably 5 to 25 mass %.

[0093] 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.

[0094] The content of the inorganic filler relative to the total amount of resin in second adhesive layer 103 is preferably 3 to 50 mass %, and more preferably 10 to 45 mass %.

[0095] 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.

[0096] 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 %.

[0097] 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.

[0098] 1.4.Antistatic layer The dicing tape 100 of this embodiment may have an antistatic layer 104 on the back side of the base layer 101. The antistatic layer 104 may be a layer composed solely of an antistatic agent, or a layer containing an antistatic agent and other components. Examples of antistatic agents include, but are not limited to, carbon nanotubes, metal oxides, polythiophenes, polyanilines, polypyrroles, dimethylaminoethyl (meth)acrylate quaternary chlorides, diethylaminoethyl (meth)acrylate quaternary chlorides, methylethylaminoethyl (meth)acrylate quaternary chlorides, p-dimethylaminostyrene quaternary chlorides, p-diethylaminostyrene quaternary chlorides, and acrylic polymers having quaternary ammonium salts in their side chains. Antistatic agents may be used alone or in combination. More specifically, examples of antistatic agents include acrylic polymers containing methyl methacrylate as the main component and 2-dimethylaminoethyl methacrylate and 2-hydroxyethyl methacrylate as structural units.

[0099] The content of the antistatic agent in the antistatic layer 104 is 40 to 100% by mass, 50 to 90% by mass, or 60 to 80% by mass, from the viewpoint of exerting a sufficient antistatic effect.

[0100] The other components are not particularly limited, but 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, the acrylic polymer may be an acrylic-silicone copolymer.

[0101] The content of other components in the antistatic layer 104 is not particularly limited, but is, for example, 0.1 to 10.0 mass %. Alternatively, the antistatic layer 104 may not contain other components.

[0102] The antistatic layer 104 may contain various additives such as a hardener, a plasticizer, an antioxidant, and a filler.

[0103] The thickness of the antistatic layer 104 is preferably 0.01 to 1 μm, more preferably 0.02 to 0.2 μm, from the viewpoint of exerting a sufficient antistatic effect.

[0104] 2. Dicing tape manufacturing method The method for producing the dicing tape 100 of this embodiment is not particularly limited, but may be, for example, the following method.

[0105] The means for forming the base 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 base 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.

[0106] 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 is removed to form the first adhesive layer 102, and the film may be attached to the base layer 101 to form the first adhesive layer 102 on the base layer 101.

[0107] The second adhesive layer 103 may be formed on the first adhesive layer 102 by the same method as for the first adhesive layer 102, or a commercially available die attach film may be attached to the first adhesive layer 102. When a commercially available 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 a molding film and then laminated on the first adhesive layer 102, thereby forming the second adhesive layer 103 on the first adhesive layer 102.

[0108] 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 200, which may then be laminated on the back surface 101b of the base layer 101, thereby forming the antistatic layer 104 on the base layer 101.

[0109] 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.

[0110] 3.Wafer processing method The wafer processing method using the dicing tape 100 of this embodiment includes a laminate production process s201 in which a laminate 500 is produced by bonding the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 to the surface of a wafer 300 in which a modified portion 302 has been formed inside by laser dicing; a low-temperature expansion process s202 in which the wafer 300 is expanded to form a die chip 303 by pushing up the expansion stage 402 from the exposed surface 100b side of the dicing tape 100 under conditions of 0°C or below; and a pick-up process s206 in which the die chip 303 is picked up from the dicing tape 100.

[0111] 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.

[0112] Each step of the wafer processing method of this embodiment will be described in detail below.

[0113] 3.1.Laminate manufacturing process Fig. 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 region 302 has been formed by laser dicing.

[0114] 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.

[0115] 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.

[0116] 3.1.1.Laser dicing process Fig. 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, division occurs at the dashed line area to form die chips 303.

[0117] 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.

[0118] 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.

[0119] The surface of the wafer 300 that is irradiated with the laser may be the non-element-formed surface 300b or the element-formed surface 300a.

[0120] 2(a) and 2(b), 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. After this, a backgrinding step is performed, which makes it easier to divide the wafer 300 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.

[0121] 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.

[0122] 3.1.2.Back grinding process Fig. 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.

[0123] Specifically, with the backgrinding tape 200 attached to the element forming surface 300a in order to protect 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.

[0124] 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 below.

[0125] 3.1.3. Bonding process Fig. 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 (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.

[0126] 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 inside due to the laser dicing process s2011.

[0127] The bonding step s2013 of this embodiment may be performed using a known device or manually, and is not particularly limited to, for example, DFM2800 manufactured by Disco Corporation.

[0128] The above-mentioned laser dicing step s2011, back grinding step s2012, and laminating step s2013 may be performed in any order. For example, after forming the 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 the 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 backgrinding the element forming surface 300b (s2012), a dicing tape 100 may be attached (s2013), and finally the modified portion may be formed by laser dicing (s2011); alternatively, after attaching the dicing tape 100 to the element forming surface 300a (s2013), and forming the modified portion by laser dicing (s2011), finally the non-element forming surface 300b may be backgrinded (s2012); alternatively, after attaching the dicing tape 100 to the element forming surface 300a (s2013), the non-element forming surface 300b may be backgrinded (s2012), and finally the modified portion may be formed by laser dicing (s2011).

[0129] 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.

[0130] 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.

[0131] 2 to 4, when steps s2011, s2012, and s2013 are performed in this order, the backgrinding 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 backgrinding 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 backgrinding tape 200 may be peeled off. Alternatively, the backgrinding tape 200 may be peeled off first, and then the dicing tape 100 may be attached.

[0132] 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 backgrinding step s2012 may be performed by laminating the backgrinding 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 backgrinding tape 200 may be peeled off. Alternatively, the backgrinding tape 200 may be peeled off first, and then the dicing tape 100 may be laminated.

[0133] 3.2.Low-temperature expansion process 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).

[0134] 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 bonded to the dicing tape 100 is divided at the modified portions 302, etc., to form individual die chips 303.

[0135] 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.

[0136] In the dicing tape 100 of this embodiment, the thickness and shear storage modulus of the first adhesive layer 102 are within appropriate ranges, so that when the expanding stage 402 is pushed up, the dicing tape 100 tends to stretch appropriately, and stress is sufficiently transmitted from the center of the wafer 300 to the wafer 300. As a result, the wafer 300 is sufficiently divided, and the wafer 300 tends to have excellent division properties at low temperatures.

[0137] The low-temperature expanding process s202 aims to divide the wafer 300 to obtain die chips 303, and is preferably carried out at a temperature below 0°C to improve the divisibility of the wafer 300 and the second adhesive layer 103, and more preferably at a temperature between -25 and 0°C.

[0138] 3.3. Room temperature expansion process 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). 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.

[0139] 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.

[0140] One of the purposes of the room-temperature expanding step s203 is to further increase the spacing between the die tips 303 formed in the low-temperature expanding step s202, and the expanding stage 402 is pushed up by an amount greater than that in the low-temperature expanding step s202. In order to improve the extensibility of the dicing tape 100 and 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.

[0141] 3.4.Heat shrink process 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). 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 3.5.Irradiation process 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). 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.

[0146] 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.

[0147] 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.

[0148] When ultraviolet light is irradiated onto 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.

[0149] 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.

[0150] 3.6.Pickup process 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). The wafer processing method of this embodiment includes a pick-up step s206 of picking up the die chip 303 from the dicing tape 100.

[0151] 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.

[0152] 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 the die tip 303 can be picked up by suction with a suction collet C.

[0153] 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. [Table 1]

[0154] Among these, it is preferable to perform steps s201, s202, s203, s204, s205, and s206 in this order.

[0155] The wafer processing method of this 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 by bonding the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 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 by bonding the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 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 by bonding the first adhesive layer 102 or the second adhesive layer 103 of the dicing tape 100 to the surface of the wafer 300 in which division grooves have been formed by blade dicing.

[0156] Although the above describes an example of 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. [Example]

[0157] 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.

[0158] 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.

[0159] Next, 60 mol% of 2-ethylhexyl acrylate and 40 mol% of 2-hydroxyethyl acrylate were copolymerized, and the hydroxyl groups of the resulting polymer were reacted with 28 mol% of 2-methacryloyloxyethyl isocyanate to obtain base polymer A. The resulting base polymer A 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.

[0160] Then, 100 parts by mass of the base polymer A obtained as described above was mixed with 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) to prepare a composition for adhesive layer.

[0161] 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 a dicing tape of Example 1.

[0162] Example 2 A dicing tape of Example 2 was obtained in the same manner as in Example 1, except that the adhesive layer composition was applied onto the base layer to form a first adhesive layer having a thickness of 5 μm.

[0163] Example 3 Base polymer B was obtained by reacting 28 mol% of 2-methacryloyloxyethyl isocyanate with the hydroxyl groups of the polymer obtained by copolymerizing 65 mol% of 2-ethylhexyl acrylate and 35 mol% of 2-hydroxyethyl acrylate. The hydroxyl groups of the polymer reacted with the isocyanate groups of 2-methacryloyloxyethyl isocyanate, resulting in base polymer B having polymerizable double bonds derived from 2-methacryloyloxyethyl isocyanate in the side chains.

[0164] A dicing tape of Example 3 was obtained in the same manner as in Example 1, except that 100 parts by mass of base polymer A was replaced with 100 parts by mass of base polymer B obtained as described above.

[0165] Example 4 A dicing tape of Example 4 was obtained in the same manner as in Example 1, except that the adhesive layer composition was applied onto the base layer to form a first adhesive layer having a thickness of 15 μm.

[0166] Example 5 A dicing tape of Example 5 was obtained in the same manner as in Example 1, except that the amount of trimethylolpropane-adducted tolylene diisocyanate (manufactured by Mitsui Chemicals, Inc.) used as a curing agent was changed to 7 parts by mass.

[0167] Comparative Example 1 A composition for adhesive layers was prepared by mixing 100 parts by mass of base polymer C, which was copolymerized with butyl acrylate, ethyl acrylate, acrylonitrile, and methoxyethyl acrylate, 50 parts by mass of a urethane oligomer UN-904M (manufactured by Negami Chemicals Co., Ltd.), 4 parts by mass of a curing agent trimethylolpropane-adducted tolylene diisocyanate (manufactured by Mitsui Chemicals Co., Ltd.), and 3 parts by mass of Omnirad-651 (manufactured by BASF).

[0168] A dicing tape of Comparative Example 1 was obtained in the same manner as in Example 1, except that the obtained composition for adhesive layer was used.

[0169] Comparative Example 2 A dicing tape of Comparative Example 2 was obtained in the same manner as in Example 1, except that the amount of trimethylolpropane-adducted tolylene diisocyanate (manufactured by Mitsui Chemicals, Inc.) used as a curing agent was changed to 20 parts by mass.

[0170] Comparative Example 3 A dicing tape of Comparative Example 3 was obtained in the same manner as in Example 1, except that a composition for adhesive layer was applied onto the base layer to form a first adhesive layer having a thickness of 2 μm.

[0171] Comparative Example 4 A dicing tape of Comparative Example 4 was obtained in the same manner as in Example 1, except that the adhesive layer composition was applied onto the base layer to form a first adhesive layer having a thickness of 25 μm.

[0172] [Adhesion strength to SUS304 before UV irradiation] The adhesive strength of the first adhesive layer to SUS304 before UV irradiation was measured in accordance with the peel adhesion strength test method described in Part 1: 90-degree peeling of JIS K6854-1:1999. Specifically, bright annealed (BA)-finished SUS304 was pressed onto the first adhesive layer with a 2 kg roller and then left to stand for 20 minutes. A 90-degree peel was then performed, and the adhesive strength was measured. The measurement temperature was 23°C, and the peeling speed was 300 mm / min.

[0173] [Shear storage modulus] The shear storage modulus of the first adhesive layer was measured in accordance with the storage modulus in shear mode described in JIS K7244-1:1998. Specifically, the adhesive layer composition obtained in each example was first applied to a release polyethylene terephthalate (PET) film to form a thin adhesive layer. A release PET film was then laminated onto the adhesive layer to prepare a sample. Next, the release PET film on one side of this sample was peeled off, and the sample was folded so that the adhesive layers overlapped. This procedure was repeated until the thickness of the adhesive layer exceeded 650 μm. After the thickness of the adhesive layer exceeded 650 μm, all of the release PET film was peeled off to obtain an adhesive layer. This adhesive layer was then stored in a constant temperature and humidity chamber at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours. Using the adhesive layer thus obtained as a sample, dynamic viscoelasticity measurements were performed under normal atmospheric conditions. The dynamic viscoelasticity measuring device used was the "MSC301" (manufactured by Anton Paar Japan). From the measurement results, the shear storage modulus at 0°C and -15°C was obtained. (Measurement conditions) Measurement device: MSC301 (manufactured by Anton Paar Japan) Sample: Thickness 650 μm Pretreatment: Keep in an atmosphere at a temperature of 23°C and a relative humidity of 50% for 40 hours Test mode: Shear Frequency: 1Hz Load: 2N Temperature range: -30℃~10℃ Heating rate: 2℃ / min Strain range: 0.05% Measurement interval: 1Point / ℃

[0174] 〔evaluation〕 (dividability) Using an expanding device, one wafer attached to the dicing tape of each example was expanded at low temperature at 0° C. to divide it into die chips, and then expanded at room temperature at 23° C. to widen the width of the die chips. Note that for Example 1, an operation of expanding at low temperature at −15° C. and then expanding at room temperature at 23° C. to widen the width of the die chips was also performed.

[0175] The ratio of the number of die chips that can actually be obtained to the ideal number of die chips that can be obtained from one wafer (division rate (%): number of die chips that can 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.

[0176] (Ring frame peeling) 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 1, 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.

[0177] During low-temperature expansion, the occurrence of peeling from the ring frame was confirmed and evaluated based on the following evaluation criteria. [Evaluation criteria] ○: No peeling from the ring frame. ×: Peeling was observed from the ring frame.

[0178] [Table 2]

[0179] In Comparative Example 2, peeling of the ring frame occurred, and evaluation of divisibility could not be performed. In Comparative Example 3, the adhesion to the ring frame was too weak, and evaluation of peeling of the ring frame and evaluation of divisibility could not be performed.

[0180] In addition, a second adhesive layer was laminated on the first adhesive layer of the dicing tape obtained in Example 1. Then, when the peeling and divisibility of the ring frame were evaluated as described above, a rating similar to that of Example 1 in Table 1 was obtained. 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, and the first adhesive layer and the second adhesive layer could be easily peeled off after ultraviolet light irradiation, allowing pickup with the second adhesive layer adhered to the die chip.

[0181] 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), and 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, and the surface is modified with organic groups such as methyl groups, average particle size 0.016 μm), and the mixture was stirred and mixed, and further kneaded for 90 minutes using a bead mill 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 1 and heated and dried at 140°C for 5 minutes to form a second adhesive layer with a thickness of 10 μm.

[0182] The thickness of the first adhesive layer in Comparative Example 3 is the coating limit thickness. [Explanation of symbols]

[0183] 100... dicing tape, 101... base layer, 102... first adhesive layer, 103... second adhesive layer, 104... antistatic layer, 200... backgrind tape, 300... wafer, 301... element, 302... modified section, 303... die chip, 400... expansion device, 401... frame, 402... expansion stage, H... heat source, L... laser source, U... ultraviolet light source, C... suction collet, N... thrust needle, P... polishing machine

Claims

1. a substrate layer having a front surface and a back surface; a first adhesive layer laminated on the surface of the base material layer, The thickness of the first adhesive layer is 3 to 20 μm, The shear storage modulus of the first adhesive layer at 0°C is 1.0 x 10 5 ~9.9 x 10 5 Pa, Dicing tape.

2. The substrate layer has an antistatic agent or an antistatic layer on the back surface side. The dicing tape according to claim 1 .

3. A second adhesive layer is provided on the first adhesive layer. The dicing tape according to claim 1 .

4. The adhesive strength of the first adhesive layer to SUS304 at 23°C is 0.50 N / 20 mm or more. The dicing tape according to claim 1 .

5. a laminate preparation step of preparing 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 by laser dicing; a low-temperature expanding step of expanding the wafer into a die chip by pushing up an expanding stage from the exposed surface side of the dicing tape under a condition of 0°C or less; a pick-up step of picking up the die chip from the dicing tape. Wafer processing method.

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

7. When the dicing tape has the second adhesive layer, In the pick-up step, peeling the second adhesive layer from the first adhesive layer after the ultraviolet irradiation, and picking up the die chip with the second adhesive layer attached thereto from the dicing tape; The wafer processing method according to claim 6.

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

9. the surface of the wafer is an element formation surface; The wafer processing method according to claim 5 .

10. After the low-temperature expanding step, the method further includes a room-temperature expanding step of expanding the dicing tape by pushing up an expanding stage from the exposed surface side of the dicing tape under a condition of 5°C or higher. The wafer processing method according to claim 5 .

11. 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. The wafer processing method according to claim 5 .

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