Adhesive tape for semiconductor processing and method for manufacturing semiconductor device

Abstract

The technical problem of the present invention is to provide an adhesive tape for semiconductor processing that can suppress chip cracking even when used in DBG or LDBG. The adhesive tape for semiconductor processing as a solution is an adhesive tape having a substrate, a buffer layer provided on at least one side of the substrate, and an adhesive layer provided on the other side of the substrate, wherein the buffer layer has a fracture energy of 13 to 80 MJ / m at 23°C. 3 .

Description

Technical Field

[0001] The present invention relates to an adhesive tape for semiconductor processing, and more particularly to an adhesive tape preferably used for temporarily holding semiconductor wafers or chips when a semiconductor device is manufactured by a method of setting grooves on the surface of the wafer or setting a modified area inside the wafer with a laser and performing wafer singulation by utilizing stress during back grinding of the wafer, and a method for manufacturing a semiconductor device using the adhesive tape. Background Art

[0002] As various electronic devices become smaller and more multifunctional, the semiconductor chips installed therein are also required to be smaller and thinner. In order to thin the chip, the back of the semiconductor wafer is usually ground to adjust the thickness. In addition, in order to obtain thinned chips, a technology called pre-cutting (DBG: Dicing Before Grinding) is sometimes used. In this technology, a dicing blade is used to form a groove of a certain depth from the surface side of the wafer, and then the back side of the wafer is ground. The wafer is singulated by grinding to obtain a chip. For DBG, since the back grinding and singulation of the wafer can be performed at the same time, thin chips can be manufactured efficiently.

[0003] Conventionally, when back grinding of a semiconductor wafer or manufacturing a chip by DBG, an adhesive tape called a back grinding sheet is usually attached to the wafer surface in order to protect the circuit on the wafer surface and hold the semiconductor wafer and the semiconductor chip.

[0004] As a back grinding sheet used in DBG, an adhesive tape having a substrate and an adhesive layer arranged on one surface of the substrate is used. As an example of such an adhesive tape, Patent Document 1 (Japanese Patent Publication No. 2015-183008) proposes an adhesive sheet having a rigid substrate, a buffer layer arranged on one side of the rigid substrate, and an adhesive layer arranged on the other side of the rigid substrate. Patent Document 1 discloses that the Young's modulus of the rigid substrate is more than 1000MPa, and when the tip of a triangular pyramidal indenter with a tip curvature radius of 100nm and an edge angle of 115° is pressed into the buffer layer at a speed of 10μm / min, the compression load reaches 2mN. The required indentation depth is more than 2.5μm. In addition, Patent Document 2 (Japanese Patent No. 5068793) proposes an adhesive sheet having an adhesive layer on at least one side of a sheet cured by an energy ray curable composition. Patent Document 2 discloses that the adhesive sheet has an elongation at break of 50% or more and a tensile elastic modulus of 10 to 1000 MPa.

[0005] In recent years, as a variation of the pre-cutting method, a method has been proposed in which a modified region is set inside the wafer using a laser, and the stress during the back grinding of the wafer is used to singulate the wafer. Hereinafter, this method is sometimes described as LDBG (Laser Dicing Before Grinding). For LDBG, since the wafer is cut in the crystal direction starting from the modified region, the generation of chipping can be reduced compared to the pre-cutting method using a dicing blade. As a result, a chip with excellent flexural strength can be obtained, which contributes to further thinning of the chip. In addition, compared to DBG, which uses a dicing blade to form a groove of a specified depth on the surface of the wafer, since there is no area where the wafer is shaved off using a dicing blade, that is, since the kerf width is extremely small, the chip yield is excellent.

[0006] For DBG and LDBG, when a grinder is used to grind the back of a wafer to make it extremely thin, if there is excess adhesive tape on the periphery of the wafer, the grinder may sometimes bite into the excess adhesive tape. Therefore, the adhesive tape is cut along the periphery of the wafer before back grinding. However, if the adhesive tape described in Patent Documents 1 and 2 is used to thin the chip to a finishing thickness of less than 30 μm, chip defects or breakage may sometimes occur (hereinafter sometimes described as "chip cracking").

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2015-183008

[0010] Patent Document 2: Japanese Patent No. 5068793 Summary of the invention

[0011] Technical Problems to be Solved by the Invention

[0012] In order to solve the above-mentioned technical problems, the inventors of the present application have conducted careful research and found that when an adhesive tape is attached to a semiconductor wafer and the adhesive tape is cut along the periphery of the wafer with a cutter, the tape scraps generated cause cracks on the chip. After attaching the adhesive tape to the wafer and cutting the adhesive tape along the periphery, the wafer is placed on a chuck table via the adhesive tape and back-grinded using a grinder or the like. At this time, if the tape scraps are located between the adhesive tape and the chuck table, the adhesive tape and the wafer will bend due to the tape scraps, and a small amount of strain will be generated on the ground surface of the wafer. When grinding such a wafer with strain, the grinder will be stuck by the strained part and cannot grind evenly, resulting in cracks that are likely to occur on the chip.

[0013] Tape scraps are produced when cutting off the adhesive tape with a cutter, specifically, because the partial structure of the adhesive tape peels off or breaks when cutting. In addition, sometimes, tape scraps are more likely to be produced because the partial structure of the adhesive tape is attached to the blade of the cutter.

[0014] The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide an adhesive tape for semiconductor processing that can suppress chip cracking even when used for DBG or LDBG.

[0015] Technical means to solve technical problems

[0016] The gist of the present invention which aims to solve the above-mentioned technical problems is as follows.

[0017] (1) An adhesive tape for semiconductor processing, comprising a substrate, a buffer layer provided on at least one side of the substrate, and an adhesive layer provided on the other side of the substrate, wherein:

[0018] The breaking energy of the buffer layer at 23°C is 13-80 MJ / m 3 .

[0019] (2) The adhesive tape for semiconductor processing according to (1), wherein the Young's modulus of the substrate at 23° C. is 1000 MPa or more.

[0020] (3) The adhesive tape for semiconductor processing according to (1) or (2), wherein the buffer layer is a cured product of a buffer layer-forming composition containing an energy-ray-polymerizable compound.

[0021] (4) The adhesive tape for semiconductor processing according to any one of (1) to (3), wherein the thickness of the adhesive layer is less than 100 μm.

[0022] (5) An adhesive tape for semiconductor processing, comprising a substrate and an adhesive layer provided on at least one side of the substrate, wherein:

[0023] The fracture energy of the substrate at 23°C is 13-80 MJ / m 3 .

[0024] (6) A method for manufacturing a semiconductor device, comprising the following steps:

[0025] A step of attaching the adhesive tape for semiconductor processing according to any one of (1) to (5) above to a surface of a semiconductor wafer and cutting the adhesive tape along the outer circumference of the semiconductor wafer;

[0026] A step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer;

[0027] A step of grinding the semiconductor wafer having the adhesive tape attached to the surface and the groove or the modified region formed thereon from the back side to singulate the semiconductor wafer into a plurality of chips using the groove or the modified region as a starting point; and

[0028] A step of peeling the adhesive tape from the plurality of chips.

[0029] Effects of the Invention

[0030] The adhesive tape for semiconductor processing of the present invention can suppress the generation of tape scraps when the adhesive tape is cut along the outer circumference of a wafer with a cutter, thereby reducing the generation of cracks in a semiconductor chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of an adhesive sheet according to a first embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of an adhesive sheet according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, the adhesive tape for semiconductor processing of the present invention will be specifically described. First, main terms used in this specification will be described.

[0034] In this specification, for example, “(meth)acrylate” is a term used to represent both “acrylate” and “methacrylate”, and the same applies to other similar terms.

[0035] "For semiconductor processing" means that it can be used in various processes such as conveying, back grinding, dicing, and picking up of semiconductor chips of semiconductor wafers.

[0036] The “front side” of a semiconductor wafer refers to the side on which a circuit is formed, and the “back side” refers to the side on which no circuit is formed.

[0037] Singulation of a semiconductor wafer refers to dividing a semiconductor wafer into individual circuits to obtain semiconductor chips.

[0038] DBG refers to a method of singulating the wafer by grinding from the back side after forming a groove of a specified depth on the surface side of the wafer. The groove formed on the surface side of the wafer can be formed by blade cutting, laser cutting, plasma cutting, etc. In addition, LDBG is a variation of DBG, which refers to a method of singulating the wafer by using a laser to set a modified area inside the wafer and utilizing the stress during the back grinding of the wafer.

[0039] Next, the composition of each component of the adhesive tape for semiconductor processing of the present invention is further described in detail. In the first embodiment, an adhesive tape having a substrate, a buffer layer disposed on at least one side of the substrate, and an adhesive layer disposed on the other side of the substrate is described. In the second embodiment, an adhesive tape having a substrate and an adhesive layer disposed on at least one side of the substrate is described. In addition, the adhesive tape for semiconductor processing of the present invention is sometimes referred to as "adhesive tape".

[0040] First embodiment

[0041] In a first embodiment of the present invention, Figure 1 As shown, the adhesive tape 10 refers to a laminate comprising a substrate 11, a buffer layer 12 disposed on at least one side of the substrate 11, and an adhesive layer 13 disposed on the other side of the substrate 11. In addition, other constituent layers other than these may also be included. For example, a primer layer may be formed on the surface of the substrate on the adhesive layer side, and a peeling sheet for protecting the adhesive layer until use may also be stacked on the surface of the adhesive layer. In addition, the substrate may be a single layer or a multilayer. The same is true for the buffer layer and the adhesive layer.

[0042] Hereinafter, the configuration of each member of the adhesive tape for semiconductor processing according to the first embodiment will be described in further detail.

[0043] [Base material]

[0044] The Young's modulus of the substrate at 23°C is preferably 1000MPa or more. When a substrate with a Young's modulus of less than 1000MPa is used, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is reduced, and the vibration during back grinding cannot be suppressed, and the semiconductor chip is prone to defects and breakage. On the other hand, by making the Young's modulus of the substrate at 23°C to be more than 1000MPa, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is improved, the vibration during back grinding can be suppressed, and the defect and breakage of the semiconductor chip can be prevented. In addition, the stress when the adhesive tape is peeled off from the semiconductor chip can be reduced, and the chip defect and breakage that occur when the tape is peeled off can be prevented. Further, the operability when the adhesive tape is attached to the semiconductor wafer can also be good. From this perspective, the Young's modulus of the substrate at 23°C is more preferably 1800-30000MPa, and more preferably 2500-6000MPa.

[0045] The thickness of the substrate is not particularly limited, but is preferably 110 μm or less, more preferably 15 to 110 μm, and further preferably 20 to 105 μm. By setting the thickness of the substrate to 110 μm or less, it is easy to control the peeling force of the adhesive tape. In addition, by setting the thickness of the substrate to 15 μm or more, the substrate is easy to function as a support for the adhesive tape.

[0046] The material of the substrate is not particularly limited as long as it satisfies the above-mentioned physical properties, and various resin films can be used. Here, as the substrate having a Young's modulus of 1000 MPa or more at 23° C., for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and wholly aromatic polyesters, polyimides, polyamides, polycarbonates, polyacetals, modified polyphenylene ethers, polyphenylene sulfides, polysulfones, polyether ketones, and biaxially stretched polypropylene resin films can be cited.

[0047] Among these resin films, it is preferable to include at least one film selected from the group consisting of polyester films, polyamide films, polyimide films, and biaxially stretched polypropylene films, it is more preferable to include a polyester film, and it is even more preferable to include a polyethylene terephthalate film.

[0048] In addition, within the scope of not impairing the effect of the present invention, the substrate may also contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc. In addition, the substrate may be transparent or opaque, and may be colored or vapor-deposited as required.

[0049] In addition, in order to improve the adhesion with at least one layer of the buffer layer and the adhesive layer, at least one surface of the substrate may be subjected to an adhesion treatment such as a corona treatment. In addition, the substrate may also be a substrate having the above-mentioned resin film and an easy-adhesive layer coated on at least one surface of the resin film.

[0050] The composition for forming the easy-adhesive layer is not particularly limited, and examples thereof include compositions containing polyester resins, urethane resins, polyesterurethane resins, acrylic resins, etc. The composition for forming the easy-adhesive layer may also contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust inhibitor, a pigment, a dye, etc. as required.

[0051] The thickness of the easy-adhesive layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. In addition, since the thickness of the easy-adhesive layer in the embodiment of the present application is smaller than the thickness of the substrate, the thickness of the resin film having the easy-adhesive layer is substantially the same as the thickness of the substrate. In addition, since the material of the easy-adhesive layer is soft, the influence on the Young's modulus is small, and even in the case of having an easy-adhesive layer, the Young's modulus of the substrate is substantially the same as the Young's modulus of the resin film.

[0052] For example, the Young's modulus of the substrate can be controlled by the selection of the resin composition, the addition of the plasticizer, the stretching conditions during the manufacture of the resin film, etc. Specifically, when a polyethylene terephthalate film is used as the substrate, if the content ratio of the ethylene component in the copolymer component increases, the Young's modulus of the substrate tends to decrease. In addition, if the blending amount of the plasticizer increases relative to the resin composition constituting the substrate, the Young's modulus of the substrate tends to decrease.

[0053] [Buffer layer]

[0054] The buffer layer relieves the stress of the semiconductor wafer during back grinding, preventing cracks and defects from occurring on the semiconductor wafer. The adhesive tape is attached to the semiconductor wafer, and after the adhesive tape is cut along the periphery, the semiconductor wafer is arranged on the chuck worktable via the adhesive tape and back grinding is performed. By making the adhesive tape have a buffer layer as a constituent layer, it is easy to properly hold the semiconductor wafer on the chuck worktable. On the other hand, since the buffer layer is softer than the base material, it is known that tape scraps will be generated when the adhesive tape is cut. In this regard, according to research results, by making the buffer layer have the following characteristics, the generation of tape scraps can be suppressed.

[0055] The fracture energy of the buffer layer at 23°C is 13-80 MJ / m 3 The adhesive tape is attached to the semiconductor wafer at room temperature (23°C) and cut along the periphery of the wafer. When the fracture energy of the buffer layer at room temperature (23°C) is 13 to 80 MJ / m 3 When the buffer layer is cut, the buffer layer will not be deformed even when it touches the blade of the cutter, or it will be deformed at the moment of contact but will instantly return to its original shape. Therefore, the buffer layer can be prevented from twisting and breaking during cutting, and the generation of tape scraps can be prevented. On the other hand, when the breaking energy of the buffer layer at 23°C is less than 13MJ / m 3 If the buffer layer touches the blade of the cutter during cutting, it will deform and remain deformed without returning to its original shape, so there is a possibility that the buffer layer will be twisted or broken and produce tape scraps. In addition, when the breaking energy of the buffer layer at 23°C is greater than 80MJ / m 3 When the buffer layer is cut, the cutter may not be able to cut it off, and the blade of the cutter may be worn.

[0056] In addition, even when the cutting is performed by heating the blade of the cutter, as long as the fracture energy of the buffer layer at 23°C is 13 to 80 MJ / m 3 , it is possible to suppress the distortion and breakage of the buffer layer during cutting, and to suppress the generation of tape scraps.

[0057] From the above perspectives, the fracture energy of the buffer layer at 23°C is preferably 13 to 60 MJ / m 3 , more preferably 14 to 58 MJ / m 3 , more preferably 15 to 37 MJ / m 3 .

[0058] The breaking energy is a value obtained by integrating the stress and strain obtained by the tensile test at 23°C based on JIS K7161:1994 and JIS K7127:1999 up to the breaking point in the stress-strain diagram. The strain (mm) can be obtained by the initial test piece length (mm) × elongation (%). In addition, the breaking stress and breaking elongation described later are the stress and elongation at the time of breaking in the above-mentioned tensile test, respectively.

[0059] From the viewpoint of obtaining the fracture energy within the above range, the fracture stress of the buffer layer at 23° C. is preferably 15 to 300 MPa, more preferably 20 to 250 MPa, and even more preferably 22 to 200 MPa.

[0060] The breaking stress can be measured based on JIS K7161:1994 and JIS K7127:1999.

[0061] Furthermore, from the viewpoint of obtaining the breaking energy within the above-mentioned range, the breaking elongation of the buffer layer at 23° C. is preferably 50 to 400%, more preferably 70 to 350%, and even more preferably 100 to 300%.

[0062] The elongation at break can be measured based on JIS K7161:1994 and JIS K7127:1999.

[0063] The buffer layer is a soft layer compared to the substrate. Therefore, the Young's modulus of the buffer layer at 23° C. is smaller than the Young's modulus of the substrate at 23° C. Specifically, the Young's modulus of the buffer layer at 23° C. is preferably less than 1000 MPa, more preferably 700 MPa or less, and further preferably 500 MPa or less.

[0064] The thickness of the buffer layer is preferably 1 to 100 μm, more preferably 5 to 80 μm, and even more preferably 10 to 60 μm. By setting the thickness of the buffer layer to the above range, stress on the buffer layer during back grinding can be appropriately relaxed.

[0065] The buffer layer is preferably a cured product of a buffer layer-forming composition containing an energy-ray polymerizable compound. Alternatively, the buffer layer may be a layer composed of a polyolefin resin film or a layer containing a polyether as a main agent.

[0066] Hereinafter, each component contained in the layer formed of the composition for buffer layer forming containing an energy beam polymerizable compound and each component contained in the layer including a polyolefin resin film will be described in order.

[0067] <Layer formed from a buffer layer-forming composition containing an energy-ray-polymerizable compound>

[0068] The buffer layer-forming composition containing an energy-ray polymerizable compound can be cured by irradiating energy rays. In addition, "energy rays" refers to ultraviolet rays, electron beams, etc., and ultraviolet rays are preferably used.

[0069] In addition, more specifically, the buffer layer forming composition containing an energy-ray polymerizable compound preferably contains carbamate (meth) acrylate (a1). By making the buffer layer forming composition contain the above-mentioned (a1) component, it is easy to make the breaking energy of the buffer layer within the above-mentioned range. In addition, it is more preferred that the buffer layer forming composition, in addition to containing the above-mentioned (a1), also contains a polymerizable compound (a2) having an alicyclic group or heterocyclic group with 6 to 20 ring atoms and / or a polymerizable compound (a3) ​​having a functional group. In addition, in addition to containing the above-mentioned (a1) to (a3) ​​components, the buffer layer forming composition may also contain a multifunctional polymerizable compound (a4). It is further preferred that the buffer layer forming composition contains a photopolymerization initiator, and may also contain other additives or resin components within the range that does not impair the effects of the present invention.

[0070] Hereinafter, each component contained in the composition for forming a buffer layer containing an energy ray polymerizable compound will be described in detail.

[0071] (Urethane (meth)acrylate (a1))

[0072] Urethane (meth)acrylate (a1) refers to a compound having at least a (meth)acryloyl group and a urethane bond, and has a property of being polymerized and cured by energy ray irradiation. Urethane (meth)acrylate (a1) is an oligomer or a polymer.

[0073] The weight average molecular weight (Mw) of component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and even more preferably 10,000 to 30,000. The number of (meth)acryloyl groups in component (a1) (hereinafter also referred to as "number of functional groups") may be monofunctional, difunctional, or trifunctional or higher, and is preferably monofunctional or difunctional.

[0074] Component (a1) can be obtained, for example, by reacting a (meth)acrylate having a hydroxyl group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyisocyanate compound. Component (a1) can be used alone or in combination of two or more.

[0075] The polyol compound as a raw material of component (a1) is not particularly limited as long as it is a compound having two or more hydroxyl groups. Specific polyol compounds include, for example, alkylene glycols, polyether polyols, polyester polyols, polycarbonate polyols, etc. Among them, polyester polyols or polycarbonate polyols are preferred.

[0076] The polyol compound may be any of a diol having a functionality of 2, a triol having a functionality of 3, or a polyol having a functionality of 4 or more. A diol having a functionality of 2 is preferred, and a polyester diol or a polycarbonate diol is more preferred.

[0077] Examples of the polyisocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and ω,ω'-diisocyanate dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylylene diisocyanate, dimethylhydrazine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate.

[0078] Among them, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred.

[0079] The urethane (meth)acrylate (a1) can be obtained by reacting a (meth)acrylate having a hydroxyl group with a terminal isocyanate urethane prepolymer obtained by reacting the above-mentioned polyol compound with a polyisocyanate compound. The (meth)acrylate having a hydroxyl group is not particularly limited as long as it is a compound having a hydroxyl group and a (meth)acryloyl group in at least one molecule.

[0080] Specific examples of (meth)acrylates having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate; hydroxyl group-containing (meth)acrylamides such as N-hydroxymethyl (meth)acrylamide; and reactants obtained by reacting (meth)acrylic acid with diglycidyl esters of vinyl alcohol, vinyl phenol, and bisphenol A.

[0081] Among them, hydroxyalkyl (meth)acrylate is preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

[0082] As conditions for reacting the terminal isocyanate urethane prepolymer with the (meth)acrylate having a hydroxyl group, it is preferable to react at 60 to 100° C. for 1 to 4 hours in the presence of a solvent and a catalyst added as needed.

[0083] The content of the component (a1) in the buffer layer forming composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, based on the total amount (100% by mass) of the buffer layer forming composition.

[0084] (Polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring atoms)

[0085] Component (a2) is a polymerizable compound having an alicyclic group or a heterocyclic group having 6 to 20 ring atoms, more preferably a compound having at least one (meth)acryloyl group, and more preferably a compound having one (meth)acryloyl group. By using component (a2), the film-forming property of the obtained buffer layer-forming composition can be improved.

[0086] In addition, the definition of component (a2) overlaps with the definition of component (a3) ​​described later, but the overlapping parts are included in component (a3). For example, a compound having at least one (meth)acryloyl group, an alicyclic group or heterocyclic group having 6 to 20 ring atoms, and a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group is included in the definitions of component (a2) and component (a3), but in the present invention, the compound is deemed to be included in component (a3).

[0087] The number of ring atoms of the alicyclic group or heterocyclic group possessed by component (a2) is preferably 6 to 20, more preferably 6 to 18, further preferably 6 to 16, particularly preferably 7 to 12. Examples of the atoms forming the ring structure of the heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

[0088] The number of ring atoms refers to the number of atoms constituting the ring itself of a compound in which atoms are bonded to form a ring structure. Atoms that do not constitute the ring (for example, hydrogen atoms bonded to atoms constituting the ring) and atoms contained in the substituent when the ring is substituted by a substituent are not included in the number of ring atoms.

[0089] Specific examples of component (a2) include (meth)acrylates containing alicyclic groups such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, and adamantyl (meth)acrylate; and (meth)acrylates containing heterocyclic groups such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate.

[0090] In addition, component (a2) can be used alone or in combination of two or more.

[0091] Among the (meth)acrylates containing an alicyclic group, isobornyl (meth)acrylate is preferred, and among the (meth)acrylates containing a heterocyclic group, tetrahydrofurfuryl (meth)acrylate is preferred.

[0092] The content of the component (a2) in the buffer layer-forming composition is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, based on the total amount (100% by mass) of the buffer layer-forming composition.

[0093] (Polymerizable compound having a functional group (a3))

[0094] Component (a3) ​​is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group, and is more preferably a compound having at least one (meth)acryloyl group, and more preferably a compound having one (meth)acryloyl group.

[0095] Component (a3) ​​has good compatibility with component (a1), and the viscosity of the buffer layer-forming composition can be easily adjusted to an appropriate range. In addition, the breaking energy of the buffer layer formed by the composition can be easily adjusted to the above range, and the buffer performance can be good even if the buffer layer is thin.

[0096] As a component (a3), a hydroxyl group-containing (meth)acrylate, an epoxy group-containing compound, an amide group-containing compound, an amino group-containing (meth)acrylate etc. are mentioned, for example.

[0097] Examples of the hydroxyl group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate.

[0098] Examples of the epoxy group-containing compound include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. Among them, epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate are preferred.

[0099] Examples of the amide group-containing compound include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide.

[0100] As an amino group-containing (meth)acrylate, a primary amino group-containing (meth)acrylate, a secondary amino group-containing (meth)acrylate, a tertiary amino group-containing (meth)acrylate, etc. are mentioned, for example.

[0101] Among them, hydroxyl group-containing (meth)acrylates are preferred, and hydroxyl group-containing (meth)acrylates having an aromatic ring such as phenylhydroxypropyl (meth)acrylate are more preferred.

[0102] In addition, the component (a3) ​​can be used alone or in combination of two or more.

[0103] In order to make the fracture energy of the buffer layer easily fall within the above-mentioned range and to improve the film-forming property of the buffer layer-forming composition, the content of component (a3) ​​in the buffer layer-forming composition is preferably 5 to 40 mass %, more preferably 7 to 35 mass %, and further preferably 10 to 30 mass %, relative to the total amount (100 mass %) of the buffer layer-forming composition.

[0104] The content ratio of component (a2) to component (a3) ​​[(a2) / (a3)] in the buffer layer-forming composition is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, further preferably 1.3 to 3.0, and particularly preferably 1.5 to 2.8.

[0105] (Multifunctional polymerizable compound (a4))

[0106] A multifunctional polymerizable compound refers to a compound having two or more photopolymerizable unsaturated groups. The photopolymerizable unsaturated group is a functional group containing a carbon-carbon double bond, for example, (meth)acryloyl, vinyl, allyl, vinylbenzyl, etc. can be listed. Two or more photopolymerizable unsaturated groups can also be combined. By reacting the photopolymerizable unsaturated group in the multifunctional polymerizable compound with the (meth)acryloyl group in component (a1), or reacting the photopolymerizable unsaturated groups in component (a4) with each other, a three-dimensional network structure (cross-linked structure) can be formed. Compared with the use of a compound containing only one photopolymerizable unsaturated group, since the cross-linked structure formed by energy ray irradiation increases when a multifunctional polymerizable compound is used, the buffer layer shows a unique viscoelasticity, and it is easy to control the fracture energy within the above range.

[0107] In addition, the definition of component (a4) overlaps with the definitions of the above-mentioned components (a2), (a3), etc., but the overlapping parts are included in component (a4). For example, a compound having an alicyclic group or heterocyclic group with 6 to 20 ring atoms and having two or more (meth)acryloyl groups is included in the definitions of component (a4) and component (a2), but in the present invention, the compound is deemed to be included in component (a4). In addition, a compound containing functional groups such as hydroxyl, epoxy, amide, and amino groups and having two or more (meth)acryloyl groups is included in the definitions of component (a4) and component (a3), but in the present invention, the compound is deemed to be included in component (a4).

[0108] From the above viewpoints, the number of photopolymerizable unsaturated groups (the number of functional groups) in the polyfunctional polymerizable compound is preferably 2 to 10, and more preferably 3 to 6.

[0109] The weight average molecular weight of the component (a4) is preferably 30 to 40,000, more preferably 100 to 10,000, and even more preferably 200 to 1,000.

[0110] Specific examples of component (a4) include diethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, vinyl (meth)acrylate, divinyl adipate, and N,N′-methylenebis(meth)acrylamide.

[0111] In addition, component (a4) may be used alone or in combination of two or more.

[0112] Among them, dipentaerythritol hexa(meth)acrylate is preferred.

[0113] The content of the component (a4) in the buffer layer forming composition is preferably 2 to 40 mass %, more preferably 3 to 20 mass %, and further preferably 5 to 15 mass % relative to the total amount (100 mass %) of the buffer layer forming composition.

[0114] (Polymerizable compound (a5) other than components (a1) to (a4))

[0115] The buffer layer-forming composition may contain other polymerizable compounds (a5) in addition to the above-mentioned components (a1) to (a4) within a range not impairing the effects of the present invention.

[0116] As component (a5), for example, (meth) acrylate alkyl esters having an alkyl group with 1 to 20 carbon atoms, vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinyl formamide, N-vinyl pyrrolidone, and N-vinyl caprolactam, etc. In addition, component (a5) can be used alone or in combination of two or more.

[0117] The content of the component (a5) in the buffer layer-forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, further preferably 0 to 5% by mass, particularly preferably 0 to 2% by mass.

[0118] (Photopolymerization Initiator)

[0119] The buffer layer-forming composition preferably further contains a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the buffer layer.

[0120] Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines or quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, 2,3-butanedione, 8-chloroanthraquinone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0121] These photopolymerization initiators can be used alone or in combination of two or more.

[0122] The content of the photopolymerization initiator in the buffer layer-forming composition is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the total amount of the energy-ray-polymerizable compounds.

[0123] (Other additives)

[0124] In the range that does not impair the effect of the present invention, the buffer layer forming composition may also contain other additives. As other additives, for example, antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. can be listed. When these additives are blended, the content of each additive in the buffer layer forming composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, relative to the total amount of 100 parts by mass of the energy ray polymerizable compound.

[0125] (Resin component)

[0126] The buffer layer forming composition may also contain a resin component within the scope of not impairing the effects of the present invention. Examples of the resin component include polyene-thiol resins, polyolefin resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene copolymers.

[0127] The content of these resin components in the buffer layer-forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, further preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass.

[0128] The buffer layer formed of the buffer layer forming composition containing an energy ray polymerizable compound is obtained by irradiating the buffer layer forming composition with the above composition with energy rays to polymerize and cure it. That is, the buffer layer is a cured product of the buffer layer forming composition.

[0129] Therefore, the buffer layer contains polymerized units derived from component (a1). In addition, the buffer layer preferably contains polymerized units derived from component (a2) and / or polymerized units derived from component (a3). Further, it may also contain polymerized units derived from component (a4) and / or polymerized units derived from component (a5). The content ratio of each polymerized unit in the buffer layer is usually consistent with the ratio (addition ratio) of each component constituting the buffer layer forming composition. For example, when the content of component (a1) in the buffer layer forming composition is 10 to 70% by mass relative to the total amount (100% by mass) of the buffer layer forming composition, the buffer layer contains 10 to 70% by mass of polymerized units derived from component (a1). In addition, when the content of component (a2) in the buffer layer forming composition is 10 to 80% by mass relative to the total amount (100% by mass) of the buffer layer forming composition, the buffer layer contains 10 to 80% by mass of polymerized units derived from component (a2). The same is true for components (a3) ​​to (a5).

[0130] <Layer Containing Polyolefin Resin Film>

[0131] By forming the buffer layer from a layer including a polyolefin resin film, it is easy to make the breaking energy of the buffer layer within the above range.

[0132] Compared to the case where the buffer layer is a layer formed by a buffer layer-forming composition containing an energy-ray polymerizable compound, when the buffer layer is a layer comprising a polyolefin resin film, the stress relaxation is sometimes low. At this time, the adhesive tape having a buffer layer formed by a layer comprising a polyolefin resin film on one side of the substrate may be warped. Although a buffer layer formed by a layer comprising a polyolefin resin film is provided on at least one side of the substrate, from the perspective of preventing such an undesirable situation, a buffer layer formed by a layer comprising a polyolefin resin film is preferably provided on both sides of the substrate.

[0133] The polyolefin resin is not particularly limited, and examples thereof include ultra-low density polyethylene (VLDPE, density: 880 kg / m 3 Above and less than 910kg / m 3 ), low-density polyethylene (LDPE, density: 910kg / m 3 Above and less than 930kg / m 3 ), medium density polyethylene (MDPE, density: 930kg / m 3 Above and less than 942kg / m 3 ), high-density polyethylene (HDPE, density: 942kg / m 3The above) polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin elastomers (TPO), cycloolefin resins, ethylene-vinyl acetate copolymers (EVA), ethylene-vinyl acetate-maleic anhydride copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylate copolymers, ethylene-(meth)acrylate-maleic anhydride copolymers, etc.

[0134] These polyolefin resins can be used alone or in combination of two or more.

[0135] From the viewpoint of obtaining a cushion layer having specific physical properties, polyethylene resins are preferred among the above-mentioned polyolefin resins, and low-density polyethylene is more preferred.

[0136] In the range that does not impair the effect of the present invention, the buffer layer may also contain additives such as plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. In addition, the buffer layer may be transparent or opaque, and may be colored or vapor-deposited as required.

[0137] In the first embodiment, when the buffer layer is a cured product of a buffer layer-forming composition containing an energy-ray polymerizable compound, the breaking energy of the buffer layer at 23° C. can be controlled by, for example, adjusting the weight average molecular weight of the urethane (meth)acrylate (a1) or the thickness of the buffer layer, or appropriately selecting the type of monomer. In addition, when the buffer layer is a layer containing a polyolefin resin film, the breaking energy of the buffer layer at 23° C. can be controlled by adjusting the density of the polyolefin or appropriately selecting an additive.

[0138] [Adhesive layer]

[0139] As long as the adhesive layer has appropriate pressure-sensitive adhesiveness at room temperature, it is not particularly limited, and the shear storage modulus at 23°C is preferably 0.05 to 0.50 MPa. Circuits are formed on the surface of the semiconductor wafer, and it usually has bumps. By making the shear storage modulus of the adhesive layer within the above range, when the adhesive tape is attached to the surface of the wafer with bumps, the bumps on the surface of the wafer can be fully contacted with the adhesive layer, and the adhesion of the adhesive layer can be properly exerted. Therefore, the adhesive tape can be reliably fixed on the semiconductor wafer, and the wafer surface can be properly protected during back grinding. From these perspectives, the shear storage modulus of the adhesive layer is preferably 0.12 to 0.35 MPa. In addition, when the adhesive layer is formed by an energy ray curable adhesive, the shear storage modulus of the adhesive layer refers to the shear storage modulus before curing by energy ray irradiation.

[0140] The shear storage modulus can be measured using the following method. Punch out an adhesive layer having a thickness of about 0.5 to 1 mm into a circle having a diameter of 7.9 mm, and use it as a measurement sample. Use a dynamic viscoelasticity measuring device ARES manufactured by Rheometric to measure the elastic modulus of the measurement sample at a frequency of 1 Hz and a temperature increase rate of 3°C / min in a temperature range of -30°C to 150°C. The elastic modulus at a measurement temperature of 23°C is taken as the shear storage modulus at 23°C.

[0141] The thickness of the adhesive layer is preferably less than 100 μm, more preferably 5 to 80 μm, and even more preferably 10 to 70 μm. When the adhesive layer is thinned in this way, the generation of tape scraps when the adhesive tape is cut can be suppressed, and cracks in the semiconductor chip generated during back grinding can be easily prevented.

[0142] The adhesive layer is formed of, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, etc., and is preferably an acrylic adhesive.

[0143] In addition, the adhesive layer is preferably formed of an energy-ray-curable adhesive. By forming the adhesive layer of an energy-ray-curable adhesive, the shear storage modulus at 23° C. can be set within the above range before curing by energy-ray irradiation, and the peeling force can be easily set to less than 1000 mN / 50 mm after curing.

[0144] Specific examples of the adhesive are described in detail below, but these specific examples are non-limiting illustrations, and the adhesive layer of the present invention should not be construed as being limited thereto.

[0145] As the energy-ray-curable adhesive, for example, an energy-ray-curable adhesive composition (hereinafter also referred to as "X-type adhesive composition") containing an energy-ray-curable compound other than the adhesive resin in addition to a non-energy-ray-curable adhesive resin (hereinafter also referred to as "adhesive resin I") can be used. In addition, as the energy-ray-curable adhesive, the following adhesive composition (hereinafter also referred to as "Y-type adhesive composition") can also be used, i.e., an energy-ray-curable adhesive resin (hereinafter also referred to as "adhesive resin II") having an unsaturated group introduced into the side chain of the non-energy-ray-curable adhesive resin as a main component, and an adhesive composition that does not contain an energy-ray-curable compound other than the adhesive resin.

[0146] Furthermore, as an energy-ray-curable adhesive, a combination of X-type and Y-type can also be used, that is, an energy-ray-curable adhesive composition (hereinafter also referred to as "XY-type adhesive composition") which contains, in addition to the energy-ray-curable adhesive resin II, an energy-ray-curable adhesive compound other than the adhesive resin.

[0147] Among them, an XY type adhesive composition is preferably used. By using an XY type adhesive composition, it has sufficient adhesive properties before curing, and on the other hand, the peeling force to the semiconductor wafer can be sufficiently reduced after curing.

[0148] However, the adhesive may also be formed from a non-energy ray-curable adhesive composition that does not cure even when irradiated with energy rays. The non-energy ray-curable adhesive composition contains at least a non-energy ray-curable adhesive resin I, and on the other hand, does not contain the above-mentioned energy ray-curable adhesive resin II and energy ray-curable compound.

[0149] In the following description, "adhesive resin" is used as a term to refer to one or both of the above-mentioned adhesive resin I and adhesive resin II. Specific adhesive resins include, for example, acrylic resins, urethane resins, rubber resins, silicone resins, etc., and acrylic resins are preferred.

[0150] Hereinafter, an acrylic adhesive using an acrylic resin as an adhesive resin will be described in more detail.

[0151] An acrylic polymer (b) is used in the acrylic resin. The acrylic polymer (b) is obtained by polymerizing a monomer containing at least an alkyl (meth)acrylate, and contains a structural unit derived from the alkyl (meth)acrylate. Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, and the alkyl group may be a straight chain or a branched chain. Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. The alkyl (meth)acrylate may be used alone or in combination of two or more.

[0152] Furthermore, from the viewpoint of improving the adhesive force of the adhesive layer, the acrylic polymer (b) preferably contains a structural unit derived from an alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms. The alkyl (meth)acrylate preferably has 4 to 12 carbon atoms, and more preferably has 4 to 6 carbon atoms. Furthermore, the alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms is preferably an alkyl acrylate.

[0153] In the acrylic polymer (b), the amount of the (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and even more preferably 50 to 90% by mass, based on the total amount of monomers constituting the acrylic polymer (b) (hereinafter also referred to as "total amount of monomers").

[0154] The acrylic polymer (b) is preferably a copolymer containing structural units derived from (meth) alkyl esters having 4 or more carbon atoms in the alkyl group, and structural units derived from (meth) alkyl esters having 1 to 3 carbon atoms in the alkyl group to adjust the elastic modulus and adhesive properties of the adhesive layer. In addition, the (meth) alkyl ester is preferably a (meth) alkyl ester having 1 or 2 carbon atoms, more preferably methyl (meth) acrylate, and most preferably methyl methacrylate. In the acrylic polymer (b), the (meth) alkyl ester having 1 to 3 carbon atoms in the alkyl group is preferably 1 to 30% by mass, more preferably 3 to 26% by mass, and further preferably 6 to 22% by mass, relative to the total amount of monomers.

[0155] Preferably, the acrylic polymer (b) has a structural unit derived from a functional group-containing monomer in addition to the structural unit derived from the (meth) alkyl ester. Examples of the functional group of the functional group-containing monomer include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. The functional group-containing monomer can react with a crosslinking agent described below to form a crosslinking starting point, or react with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (b).

[0156] As the functional group-containing monomer, there can be listed hydroxyl-containing monomers, carboxyl-containing monomers, amino-containing monomers, epoxy-containing monomers, etc. These monomers can be used alone or in combination of two or more. Among them, hydroxyl-containing monomers and carboxyl-containing monomers are preferred, and hydroxyl-containing monomers are more preferred.

[0157] Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0158] Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid and anhydrides thereof; and 2-carboxyethyl methacrylate.

[0159] The amount of the functional group-containing monomer is preferably 1 to 35% by mass, more preferably 3 to 32% by mass, and even more preferably 6 to 30% by mass, based on the total amount of monomers constituting the acrylic polymer (b).

[0160] Furthermore, the acrylic polymer (b) may contain, in addition to the above-mentioned structural units, structural units derived from monomers copolymerizable with the above-mentioned acrylic monomers, such as styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

[0161] The acrylic polymer (b) can be used as a non-energy-ray-curable adhesive resin I (acrylic resin). In addition, as an energy-ray-curable acrylic resin, there can be cited a resin obtained by reacting a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound) with a functional group of the acrylic polymer (b).

[0162] The unsaturated group-containing compound is a compound having both a substituent capable of bonding to the functional group of the acrylic polymer (b) and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include (meth)acryloyl, vinyl, allyl, and vinylbenzyl, with (meth)acryloyl being preferred.

[0163] In addition, as the substituent possessed by the unsaturated group-containing compound and capable of bonding to the functional group, there can be listed an isocyanate group, a glycidyl group, etc. Therefore, as the unsaturated group-containing compound, for example, there can be listed (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, (meth)glycidyl (meth)acrylate, etc.

[0164] Furthermore, the unsaturated group-containing compound preferably reacts with part of the functional groups of the acrylic polymer (b). Specifically, it is preferred that the unsaturated group-containing compound reacts with 50 to 98 mol% of the functional groups of the acrylic polymer (b), and more preferably reacts with 55 to 93 mol% of the functional groups of the acrylic polymer (b). In this way, in the energy-ray-curable acrylic resin, part of the functional groups remain without reacting with the unsaturated group-containing compound, making it easy to crosslink with a crosslinking agent.

[0165] The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1,600,000, more preferably 400,000 to 1,400,000, and even more preferably 500,000 to 1,200,000.

[0166] (Energy ray curable compound)

[0167] As the energy-ray-curable compound contained in the X-type or XY-type adhesive composition, a monomer or oligomer having an unsaturated group in the molecule and being polymerizable and curable by energy-ray irradiation is preferred.

[0168] Examples of such energy-ray-curable compounds include poly(meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate; and oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate.

[0169] Among them, urethane (meth)acrylate oligomers are preferred because they have a relatively high molecular weight and are less likely to reduce the shear storage modulus of the pressure-sensitive adhesive layer.

[0170] The molecular weight of the energy ray curable compound (weight average molecular weight in the case of an oligomer) is preferably 100 to 12,000, more preferably 200 to 10,000, further preferably 400 to 8,000, particularly preferably 600 to 6,000.

[0171] The content of the energy-ray curable compound in the X-type adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and even more preferably 60 to 90 parts by mass, based on 100 parts by mass of the adhesive resin.

[0172] On the other hand, the content of the energy-ray curable compound in the XY-type adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and further preferably 3 to 15 parts by mass, relative to 100 parts by mass of the adhesive resin. In the XY-type adhesive composition, since the adhesive resin is energy-ray curable, even if the content of the energy-ray curable compound is small, the peeling force can be sufficiently reduced after energy ray irradiation.

[0173] (Crosslinking agent)

[0174] The adhesive composition preferably further contains a crosslinking agent. The crosslinking agent, for example, reacts with a functional group of a functional group-containing monomer from the adhesive resin to crosslink the adhesive resins. As a crosslinking agent, for example, isocyanate crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy crosslinking agents such as ethylene glycol glycidyl ether; aziridine crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; chelate crosslinking agents such as aluminum chelates, etc. These crosslinking agents can be used alone or in combination of two or more.

[0175] Among them, isocyanate crosslinking agents are preferred from the viewpoints of increasing cohesive force and adhesive strength and from the viewpoint of easy availability.

[0176] From the viewpoint of promoting the crosslinking reaction, the amount of the crosslinking agent blended is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass, based on 100 parts by mass of the adhesive resin.

[0177] (Photopolymerization Initiator)

[0178] When the adhesive composition is energy-ray-curable, the adhesive composition preferably further contains a photopolymerization initiator. By containing a photopolymerization initiator, the curing reaction of the adhesive composition can be sufficiently carried out even by energy rays with relatively low energy such as ultraviolet rays.

[0179] Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines or quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, 2,3-butanedione, 8-chloroanthraquinone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0180] These photopolymerization initiators can be used alone or in combination of two or more.

[0181] The amount of the photopolymerization initiator to be blended is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the adhesive resin.

[0182] (Other additives)

[0183] The adhesive composition may also contain other additives within the scope of not impairing the effect of the present invention. As other additives, for example, antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. can be listed. When these additives are blended, the blending amount of the additives is preferably 0.01 to 6 parts by mass relative to 100 parts by mass of the adhesive resin.

[0184] Furthermore, from the viewpoint of improving coating properties on a substrate, a cushion layer, or a release sheet, the adhesive composition may be further diluted with an organic solvent to be in the form of a solution of the adhesive composition.

[0185] Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.

[0186] In addition, the organic solvent used in synthesizing the adhesive resin may be used as it is, or one or more organic solvents other than the organic solvent used in the synthesis may be added so that the adhesive composition solution can be uniformly applied.

[0187] [Peel sheet]

[0188] A release sheet may also be attached to the surface of the adhesive tape. Specifically, the release sheet may be attached to the surface of the adhesive layer of the adhesive tape. By attaching the release sheet to the surface of the adhesive layer, the adhesive layer is protected during transportation and storage. The release sheet is attached to the adhesive tape in a removable manner and can be removed by peeling it off from the adhesive tape before using the adhesive tape (i.e., before attaching the wafer).

[0189] The release sheet may be a release sheet at least one surface of which has been subjected to a release treatment. Specifically, the release sheet may include a release sheet obtained by applying a release agent on the surface of a release sheet substrate.

[0190] As the release sheet substrate, a resin film is preferred, and examples of the resin constituting the resin film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, and polyolefin resins such as polypropylene resin and polyethylene resin. Examples of the release agent include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, and fluorine resins.

[0191] The thickness of the release sheet is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 150 μm.

[0192] [Manufacturing method of adhesive tape]

[0193] The adhesive tape of the present invention may be produced by any known method without particular limitation.

[0194] For example, a method for producing an adhesive tape including a substrate, a cushion layer provided on one surface of the substrate, and an adhesive layer provided on the other surface of the substrate is as follows.

[0195] When the buffer layer is formed by a buffer layer-forming composition containing an energy-ray polymerizable compound, the buffer layer-forming composition is applied to a release sheet and cured to provide the buffer layer, the buffer layer is laminated to the substrate, and the release sheet is removed to obtain a laminate of the buffer layer and the substrate. In addition, when the buffer layer is a layer containing a polyolefin resin film, the buffer layer and the substrate are laminated to obtain a laminate of the buffer layer and the substrate.

[0196] Furthermore, the adhesive layer provided on the release sheet can be attached to the substrate side of the laminate to produce an adhesive tape having a release sheet attached to the surface of the adhesive layer. The release sheet attached to the surface of the adhesive layer can be removed by appropriately peeling it off before using the adhesive tape.

[0197] As a method for forming a buffer layer on a release sheet, a known coating method can be used to directly apply a buffer layer forming composition on the release sheet to form a coating film, and the coating film is irradiated with energy rays to form the buffer layer. In addition, the buffer layer can also be formed by directly coating the buffer layer forming composition on one side of the substrate and drying it by heating or irradiating the coating film with energy rays.

[0198] As the coating method of the buffer layer forming composition, for example, spin coating, spray coating, rod coating, knife coating, roll coating, blade coating, die coating, gravure coating, etc. can be listed. In addition, in order to improve the coating property, an organic solvent can also be blended into the buffer layer forming composition, and the solution can be coated on the release sheet.

[0199] When the buffer layer forming composition contains an energy ray polymerizable compound, it is preferably cured by irradiating the coating film of the buffer layer forming composition with energy rays to form a buffer layer. The curing of the buffer layer can be carried out by a single curing treatment, or it can be carried out in multiple times. For example, the coating film on the release sheet can be completely cured to form a buffer layer and then attached to the substrate, or the coating film can be not completely cured to form a semi-cured buffer layer forming film, and after the buffer layer forming film is attached to the substrate, the energy ray is irradiated again to fully cure it to form a buffer layer. As the energy ray irradiated in the curing treatment, ultraviolet rays are preferred. In addition, although the coating film of the buffer layer forming composition can be exposed during curing, it is preferably cured by irradiating energy rays in a state where the coating film is covered with a release sheet and a substrate and the coating film is not exposed.

[0200] When buffer layer is a layer comprising a polyolefin resin film, buffer layer can be adhered to substrate by extrusion lamination. Specifically, polyolefin resins constituting buffer layer are melted and kneaded using a T-die film making machine, substrate is moved at a certain speed, and melted polyolefin resins are extrusion laminated on one side of substrate simultaneously. In addition, buffer layer can also be directly laminated on substrate by heat sealing etc. Further, methods such as dry lamination method can also be used, laminated via easy adhesive layer.

[0201] As a method of forming the adhesive layer on the release sheet, the adhesive (adhesive composition) can be directly applied on the release sheet using a known coating method and the applied film can be heated and dried to form the adhesive layer.

[0202] In addition, adhesive (adhesive composition) can also be directly applied on one side of the substrate to form an adhesive layer. As the coating method of the adhesive, spray coating, rod coating, blade coating, roller coating, scraper coating, die coating, gravure coating, etc. disclosed in the manufacturing method of the buffer layer can be listed.

[0203] In the method for producing an adhesive tape having cushion layers on both sides of a substrate, for example, a laminate having a cushion layer, a substrate and a cushion layer laminated in this order is obtained by the above method, and then an adhesive layer is formed on one side of the cushion layer.

[0204] [Method for manufacturing semiconductor device]

[0205] The adhesive tape of the present invention is preferably attached to the surface of a semiconductor wafer and used when performing back grinding of the wafer. It is more preferred to suitably use the adhesive tape of the present invention in a DBG that simultaneously performs back grinding of the wafer and singulation of the wafer. It is particularly preferred to suitably use the adhesive tape of the present invention in an LDBG that can obtain a chipset with a smaller kerf width when singulating a semiconductor wafer. In addition, a "chipset" refers to a plurality of semiconductor chips in a wafer shape held on the adhesive tape of the present invention.

[0206] As a non-limiting example of use of the adhesive tape, a method for manufacturing a semiconductor device will be described in more detail below.

[0207] Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4.

[0208] Step 1: a step of attaching the adhesive tape to the surface of the semiconductor wafer and cutting the adhesive tape along the outer circumference of the semiconductor wafer;

[0209] Step 2: a step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer;

[0210] Step 3: grinding the semiconductor wafer having the adhesive tape attached to the surface and the groove or modified region formed thereon from the back side, and singulating the semiconductor wafer into a plurality of chips using the groove or modified region as a starting point; and

[0211] Step 4: a step of peeling the adhesive tape from the singulated semiconductor wafer (ie, a plurality of semiconductor chips).

[0212] Hereinafter, each step of the method for manufacturing the semiconductor device will be described in detail.

[0213] (Process 1)

[0214] In step 1, the adhesive tape of the present invention is attached to the surface of the semiconductor wafer via the adhesive layer, and is cut along the periphery of the semiconductor wafer. The adhesive tape is attached in a manner covering the semiconductor wafer and the peripheral workbench extending at its periphery. In addition, the adhesive tape is cut along the periphery of the semiconductor wafer using a cutter or the like. The cutting speed is generally 10 to 300 mm / s. The temperature of the blade of the cutter during cutting may be room temperature, and the blade of the cutter may be heated before cutting.

[0215] This step may be performed before step 2 described later, or after step 2. For example, when a modified region is formed in a semiconductor wafer, step 1 is preferably performed before step 2. On the other hand, when a groove is formed on the surface of a semiconductor wafer by dicing or the like, step 1 is performed after step 2. That is, through this step 1, an adhesive tape is attached to the surface of the wafer having the groove formed in step 2 described later.

[0216] The semiconductor wafer used in the present manufacturing method may be a silicon wafer, and may also be a wafer of gallium arsenide, silicon carbide, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or the like, or a glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is generally about 500 to 1000 μm. In addition, the semiconductor wafer generally has a circuit formed on its surface. Various methods including etching, stripping, and other conventional methods can be used to form a circuit on the wafer surface.

[0217] (Process 2)

[0218] In step 2, a trench is formed from the surface side of the semiconductor wafer, or a modified region is formed inside the semiconductor wafer from the surface or back side of the semiconductor wafer.

[0219] The groove formed in this process is a groove whose depth is shallower than the thickness of the semiconductor wafer. The groove can be formed by dicing using a conventionally known wafer dicing device or the like. In addition, in step 3 described later, the semiconductor wafer is divided into a plurality of semiconductor chips along the groove.

[0220] In addition, the modified region is a portion of the semiconductor wafer that has been embrittled, and is a region that becomes the starting point for the semiconductor wafer to be broken and singulated into semiconductor chips. The reason why the semiconductor wafer is broken is that the semiconductor wafer becomes thinner due to grinding in the grinding process, or the semiconductor wafer is applied with a force caused by grinding. That is, in step 2, grooves and modified regions are formed along the dividing lines when the semiconductor wafer is divided and singulated into semiconductor chips in step 3 described later.

[0221] The formation of the modified region is performed by irradiating the semiconductor wafer with a laser focused on the inside of the semiconductor wafer, and the modified region is formed inside the semiconductor wafer. The laser irradiation can be performed from the surface side of the semiconductor wafer or from the back side. In addition, in the scheme of forming the modified region, when the process 2 is performed after the process 1 and the laser irradiation is performed from the wafer surface, the semiconductor wafer is irradiated with the laser through the adhesive tape.

[0222] A semiconductor wafer with an adhesive tape attached and grooves or a modified region formed thereon is placed on a work plate and held by suction on a chuck table. At this time, the surface side of the semiconductor wafer is arranged and suctioned on the work table side.

[0223] (Process 3)

[0224] After step 1 and step 2, the back side of the semiconductor wafer on the chuck table is ground to separate the semiconductor wafer into a plurality of semiconductor chips.

[0225] Here, when a groove is formed on the semiconductor wafer, back grinding is performed in a manner that the semiconductor wafer is thinned to at least the bottom of the groove. Through the back grinding, the groove becomes a cut that penetrates the wafer, and the semiconductor wafer is divided by the cut to singulate into individual semiconductor chips.

[0226] On the other hand, when a modified region is formed, the grinding surface (back side of the wafer) can be ground to reach the modified region, but it is not necessary to reach the modified region precisely. That is, the semiconductor wafer can be ground to a position close to the modified region in such a way that it is broken and singulated into semiconductor chips starting from the modified region. For example, the actual singulation of the semiconductor chips can also be performed by attaching a pickup tape described later and then stretching the pickup tape.

[0227] Alternatively, dry polishing can be performed after back grinding and before chip pickup.

[0228] The shape of the singulated semiconductor chips can be square or rectangular or other elongated shapes. In addition, the thickness of the singulated semiconductor chips is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. By using LDBG to singulate the wafer by setting a modified area inside the wafer with a laser and utilizing the stress during back grinding of the wafer, it is easy to make the thickness of the singulated semiconductor chips less than 50 μm, and more preferably 10 to 45 μm. In addition, the size of the singulated semiconductor chips is not particularly limited, but the chip size is preferably less than 600 mm. 2 , preferably less than 400mm 2 , further preferably less than 300mm 2 .

[0229] When the adhesive tape of the present invention is used, even such a thin and / or small semiconductor chip can be prevented from being cracked during back grinding (step 3) and during peeling of the adhesive tape (step 4).

[0230] (Process 4)

[0231] Next, the semiconductor processing adhesive tape is peeled off from the singulated semiconductor wafer (ie, a plurality of semiconductor chips). This step is performed, for example, by the following method.

[0232] First, when the adhesive layer of the adhesive tape is formed by an energy-ray-curable adhesive, the adhesive layer is cured by irradiating energy rays. Next, the pickup tape is attached to the back side of the singulated semiconductor wafer, and the position and direction are aligned in a manner that it can be picked up. At this time, the ring frame arranged on the outer peripheral side of the wafer is also attached to the pickup tape, and the outer peripheral edge of the pickup tape is fixed to the ring frame. The wafer and the ring frame can be attached to the pickup tape at the same time, or they can be attached at different times. Next, the adhesive tape is peeled off from the multiple semiconductor chips held on the pickup tape.

[0233] Then, the plurality of semiconductor chips on the pickup tape are picked up and fixed on a substrate or the like, thereby manufacturing a semiconductor device.

[0234] The pickup tape is not particularly limited, and may be, for example, an adhesive tape including a base material and an adhesive layer provided on at least one surface of the base material.

[0235] In addition, an adhesive tape can also be used instead of the pickup tape. As the adhesive tape, there can be listed a laminate of a film adhesive and a release sheet, a laminate of a dicing tape and a film adhesive, a dicing-bonding tape composed of an adhesive layer and a release sheet having both the function of a dicing tape and a die bonding tape, and the like. In addition, before attaching the pickup tape, a film adhesive can be attached to the back side of the singulated semiconductor wafer. When a film adhesive is used, the shape of the film adhesive can be the same as that of the wafer.

[0236] When using an adhesive tape, or before attaching a pickup tape, when a film adhesive is attached to the back side of a singulated semiconductor wafer, multiple semiconductor chips on the adhesive tape or pickup tape are picked up together with the adhesive layer that is divided into the same shape as the semiconductor chip. Then, the semiconductor chip is fixed to a substrate or the like via the adhesive layer to manufacture a semiconductor device. The division of the adhesive layer can be performed by laser and expansion.

[0237] In the above, an example of using the adhesive tape of the present invention for singulating semiconductor wafers by DBG or LDBG is described, but the adhesive tape of the present invention can also be suitably used in LDBG to obtain a chip set with a smaller cut width and further thinning when singulating semiconductor wafers. In addition, the adhesive tape of the present invention can also be used in conventional back grinding, and can also be used to temporarily hold the workpiece when processing glass, ceramics, etc. In addition, it can also be used as various re-peelable adhesive tapes.

[0238] Second embodiment

[0239] In the second embodiment of the present invention, Figure 2 As shown, the adhesive tape 20 refers to a laminate comprising a substrate 21 and an adhesive layer 13 disposed on at least one side of the substrate. In addition, other constituent layers other than this may also be included. For example, a primer layer may be formed on the surface of the substrate on the adhesive layer side, and a peeling sheet for protecting the adhesive layer until use may also be stacked on the surface of the adhesive layer. In addition, the substrate may be a single layer or a multilayer. The same is true for the adhesive layer.

[0240] Hereinafter, the configuration of each member of the adhesive tape for semiconductor processing according to the second embodiment will be described in further detail.

[0241] [Base material]

[0242] The fracture energy of the substrate at 23°C is 13-80 MJ / m 3 The adhesive tape is attached to the semiconductor wafer at room temperature (23°C) and cut along the periphery of the wafer. When the fracture energy of the substrate at room temperature (23°C) is 13 to 80 MJ / m3 When the substrate is cut, the substrate will not be deformed even if it touches the blade of the cutter, or it will be deformed at the moment of contact but will instantly return to its original shape. Therefore, the substrate can be prevented from twisting and breaking during cutting, and the generation of tape scraps can be suppressed. On the other hand, when the fracture energy of the substrate at 23°C is less than 13MJ / m 3 If the substrate touches the blade of the cutter during cutting, it will deform and remain deformed without returning to its original shape, so there is a possibility that the substrate will be twisted or broken and tape scraps will be generated. In addition, when the fracture energy of the substrate at 23°C is greater than 80MJ / m 3 When the substrate is cut, the cutter may not be able to cut the substrate, and the cutter blade may be worn.

[0243] In addition, even when the cutting blade is heated to cut, as long as the fracture energy of the substrate at 23°C is 13 to 80 MJ / m 3 , it is possible to suppress the distortion and breakage of the substrate during cutting, and to suppress the generation of tape scraps.

[0244] From the above perspectives, the fracture energy of the substrate at 23°C is preferably 13 to 60 MJ / m 3 , more preferably 23 to 58 MJ / m 3 , more preferably 25 to 56 MJ / m 3 .

[0245] The breaking energy is a value obtained by integrating the stress and strain obtained by the tensile test at 23°C based on JIS K7161:1994 and JIS K7127:1999 up to the breaking point in the stress-strain diagram. The strain (mm) can be obtained by the initial test piece length (mm) × elongation (%). In addition, the breaking stress and breaking elongation described later are the stress and elongation at the time of breaking in the above-mentioned tensile test, respectively.

[0246] From the viewpoint of obtaining the fracture energy within the above range, the fracture stress of the substrate at 23° C. is preferably 15 to 300 MPa, more preferably 20 to 250 MPa, and even more preferably 22 to 200 MPa.

[0247] The breaking stress can be measured based on JIS K7161:1994 and JIS K7127:1999.

[0248] Furthermore, from the viewpoint of obtaining the breaking energy within the above range, the breaking elongation of the substrate at 23° C. is preferably 50 to 400%, more preferably 70 to 350%, and even more preferably 100 to 300%.

[0249] The elongation at break can be measured based on JIS K7161:1994 and JIS K7127:1999.

[0250] The Young's modulus of the substrate at 23°C is preferably 1000MPa or more. When a substrate with a Young's modulus of less than 1000MPa is used, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is reduced, and the vibration during back grinding cannot be suppressed, and the semiconductor chip is prone to defects and breakage. On the other hand, by making the Young's modulus of the substrate at 23°C to be more than 1000MPa, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is improved, the vibration during back grinding can be suppressed, and the semiconductor chip can be prevented from being defective and damaged. In addition, the stress when the adhesive tape is peeled off from the semiconductor chip can be reduced, and the chip defects and breakage that occur when the tape is peeled off can be prevented. Further, the operability when the adhesive tape is attached to the semiconductor wafer can also be good. From these perspectives, the Young's modulus of the substrate at 23°C is preferably 1800-30000MPa, more preferably 2500-6000MPa.

[0251] The thickness of the substrate is not particularly limited, but is preferably 110 μm or less, more preferably 15 to 110 μm, and further preferably 20 to 105 μm. By setting the thickness of the substrate to 110 μm or less, it is easy to control the peeling force of the adhesive tape. In addition, by setting the thickness of the substrate to 15 μm or more, the substrate is easy to function as a support for the adhesive tape.

[0252] The material of the substrate is not particularly limited as long as it satisfies the above-mentioned physical properties, and various resin films can be used. Here, as the substrate having a Young's modulus of 1000 MPa or more at 23° C., for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and wholly aromatic polyesters, polyimides, polyamides, polycarbonates, polyacetals, modified polyphenylene ethers, polyphenylene sulfides, polysulfones, polyether ketones, and biaxially stretched polypropylene resin films can be cited.

[0253] Among these resin films, it is preferable to include at least one film selected from the group consisting of polyester films, polyamide films, polyimide films, and biaxially stretched polypropylene films, it is more preferable to include a polyester film, and it is even more preferable to include a polyethylene terephthalate film.

[0254] In the second embodiment, as long as the breaking energy is within the above range, a substrate having a Young's modulus of less than 1000 MPa at 23° C. may be used. For example, by forming the substrate using a layer including a polyolefin resin film, the breaking energy of the substrate can be easily within the above range.

[0255] The polyolefin resin is not particularly limited, and examples thereof include ultra-low density polyethylene (VLDPE, density: 880 kg / m 3 Above and less than 910kg / m 3 ), low-density polyethylene (LDPE, density: 910kg / m 3 Above and less than 930kg / m 3 ), medium density polyethylene (MDPE, density: 930kg / m 3 Above and less than 942kg / m 3 ), high-density polyethylene (HDPE, density: 942kg / m 3 The above) polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin elastomers (TPO), cycloolefin resins, ethylene-vinyl acetate copolymers (EVA), ethylene-vinyl acetate-maleic anhydride copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylate copolymers, ethylene-(meth)acrylate-maleic anhydride copolymers, etc.

[0256] These polyolefin resins can be used alone or in combination of two or more.

[0257] From the viewpoint of obtaining a substrate having specific physical properties, polyethylene resins are preferred among the above-mentioned polyolefin resins, and low-density polyethylene is more preferred.

[0258] In addition, within the scope of not damaging the effect of the present invention, the substrate may also contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc. In addition, the substrate may be transparent or opaque, and may be colored or vapor-deposited as required.

[0259] In order to improve the adhesion with the adhesive layer, at least one surface of the substrate may be subjected to an adhesion treatment such as a corona treatment. In addition, the substrate may have the above-mentioned resin film and the coating film having an easy-adhesion layer on at least one surface of the resin film.

[0260] The composition for forming the easy-adhesive layer is not particularly limited, and examples thereof include compositions containing polyester resins, urethane resins, polyesterurethane resins, acrylic resins, etc. The composition for forming the easy-adhesive layer may also contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust inhibitor, a pigment, a dye, etc. as required.

[0261] The thickness of the easy-adhesive layer is preferably 0.01 to 10 μm, and more preferably 0.03 to 5 μm. In addition, since the thickness of the easy-adhesive layer in the embodiment of the present application is smaller than the thickness of the substrate, the thickness of the resin film having the easy-adhesive layer is substantially the same as the thickness of the substrate. In addition, since the material of the easy-adhesive layer is soft, the effect on the fracture energy is small, and even in the case of having an easy-adhesive layer, the fracture energy of the substrate is substantially the same as the fracture energy of the resin film.

[0262] For example, the fracture energy of the substrate can be controlled by the selection of the resin composition, the addition of the plasticizer, the stretching conditions during the manufacture of the resin film, etc. Specifically, when a polyethylene terephthalate film is used as the substrate, if the content ratio of the ethylene component in the copolymer component increases, the fracture energy of the substrate tends to decrease. In addition, if the blending amount of the plasticizer increases relative to the resin composition constituting the substrate, the fracture energy of the substrate tends to decrease.

[0263] The adhesive layer, the release sheet, and the method for manufacturing the semiconductor device of the second embodiment can be the same as those of the first embodiment.

[0264] In addition, the method for producing the adhesive tape can be the same as that of the first embodiment except that the cushion layer is not provided.

[0265] Example

[0266] Hereinafter, the present invention will be described in further detail based on examples, but the present invention is not limited to these examples.

[0267] The measurement and evaluation methods are as follows: For an adhesive sheet composed of a substrate and an adhesive layer, the outermost layer in Table 1 refers to the substrate, and for an adhesive sheet composed of a substrate, a cushion layer, and an adhesive layer, the outermost layer in Table 1 refers to the cushion layer.

[0268] [Breaking energy, Young's modulus, elongation at break, breaking stress]

[0269] The fracture energy, Young's modulus, elongation at break and fracture stress of the substrate and the buffer layer were measured using a precision universal testing machine (manufactured by Shimadzu Corporation, device name "AUTOGRAPH AG-IS"). Specifically, a test specimen with a width of 1.5 mm × a length of 150 mm × a thickness of 0.2 mm, which was composed of the substrate used in Examples 5 and 6 or the cured product of the buffer layer-forming composition used in Examples 1 to 4 and Comparative Examples 1 and 2, was prepared. The test specimen was measured under the conditions of a chuck spacing of 100 mm (25 mm at each end of the length direction of the test specimen was fixed to the device), a tensile speed of 200 mm / second, 23°C, and 50% RH.

[0270] [Evaluation of tape scraps]

[0271] The adhesive tapes for semiconductor processing produced in Examples 1 to 6 and Comparative Examples 1 and 2 were attached to a silicon wafer having a diameter of 12 inches and a thickness of 775 μm using a back grinding tape mounter (manufactured by LINTEC CORPORATION, device name "RAD-3510F / 12"), and cut along the outer periphery of the silicon wafer. The cross section of the cut adhesive tape was observed using a scanning electron microscope (SEM) and evaluated according to the following criteria.

[0272] 1: The cross section of the tablet is rough and broken in many places.

[0273] 2: The cross section of the tablet was rough and breakage was observed.

[0274] 3: The cross section of the tablet was slightly rough, and some breakage was observed.

[0275] 4: Although the cross section of the sheet was slightly rough, no breakage was observed.

[0276] 5: Roughness and breakage were not observed in the cross section of the sheet.

[0277] In addition, the mass parts of the following Examples and Comparative Examples are all based on solid content.

[0278] [Example 1]

[0279] (1) Base material

[0280] As a substrate, a PET film with an adhesive layer on both sides (COSMOSHINEA 4300 manufactured by TOYOBO CO., LTD., thickness: 50 μm, Young's modulus at 23° C.: 2550 MPa) was prepared.

[0281] (2) Buffer layer

[0282] (Synthesis of urethane acrylate oligomers)

[0283] Polycarbonate diol and isophorone diisocyanate were reacted to obtain an isocyanate-terminated urethane prepolymer, and 2-hydroxyethyl acrylate was reacted with the prepolymer to obtain a urethane acrylate oligomer (UA-1) having a weight average molecular weight (Mw) of about 25,000.

[0284] (Preparation of Buffer Layer-Forming Composition)

[0285] 20 parts by mass of the above-synthesized urethane acrylate oligomer (UA-1), 70 parts by mass of isobornyl acrylate (IBXA) and 10 parts by mass of phenyl hydroxypropyl acrylate (HPPA) were mixed, and 2.0 parts by mass of 2-hydroxy-2-methyl-1-phenyl-propane-1-one (manufactured by BASF JAPAN, product name "IRGACURE 1173") as a photopolymerization initiator was further mixed to prepare a composition for forming a buffer layer.

[0286] (3)Adhesive layer

[0287] (Preparation of Adhesive Composition)

[0288] An acrylic polymer (b) is obtained by copolymerizing 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA), and the acrylic polymer (b) is reacted with 2-methacryloyloxyethyl isocyanate (MOI) in a manner that 90 mol % of hydroxyl groups among all hydroxyl groups of the acrylic polymer (b) are added to obtain an energy-ray-curable acrylic resin (Mw: 500,000).

[0289] To 100 parts by mass of the energy-ray-curable acrylic resin, 6 parts by mass of a multifunctional urethane acrylate as an energy-ray-curable compound, 1 part by mass of an isocyanate crosslinking agent (manufactured by TOSOH CORPORATON, product name: "CORONATE L"), and 1 part by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide as a photopolymerization initiator were added, and the mixture was diluted with methyl ethyl ketone to prepare a coating liquid of an adhesive composition having a solid content concentration of 32% by mass.

[0290] (4) Production of adhesive tape

[0291] The coating liquid of the adhesive composition obtained above was applied onto the release-treated surface of a release sheet (manufactured by LINTEC CORPORATION, trade name "SP-PET381031") and heated and dried to form an adhesive layer having a thickness of 30 μm on the release sheet.

[0292] The buffer layer forming composition was applied to the release treated surface of another release sheet (manufactured by LINTEC CORPORATION, trade name "SP-PET381031") to form a coating film. The coating film was then irradiated with ultraviolet rays to semi-cure the coating film to form a buffer layer forming film with a thickness of 53 μm.

[0293] In addition, a conveyor-type ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., device name "US2-0801") and a high-pressure mercury lamp (manufactured by Eye Graphics Co., Ltd., device name "H08-L41") were used, with a lamp height of 230 mm, an output of 80 mW / cm, and an illumination of 90 mW / cm at a wavelength of 365 nm. 2 , irradiation dose is 50mJ / cm 2 The above-mentioned ultraviolet irradiation is carried out under the irradiation conditions of.

[0294] Then, the surface of the formed buffer layer forming film was attached to the substrate, and ultraviolet rays were irradiated again from the release sheet side of the buffer layer forming film to completely cure the buffer layer forming film, thereby forming a buffer layer with a thickness of 53 μm. In addition, the above-mentioned ultraviolet irradiation device and high-pressure mercury lamp were used at a lamp height of 220 mm, a converted output of 120 mW / cm, and an illumination of 160 mW / cm at a wavelength of 365 nm. 2 , irradiation dose is 650mJ / cm 2 The above-mentioned ultraviolet irradiation is carried out under the irradiation conditions of.

[0295] Then, the adhesive layer is bonded to the surface of the substrate opposite to the surface on which the buffer layer is formed, thereby producing an adhesive tape for semiconductor processing.

[0296] [Example 2]

[0297] In the synthesis of the urethane acrylate oligomer of the buffer layer, a urethane acrylate oligomer (UA-2) having a weight average molecular weight (Mw) of about 20,000 was obtained. In the preparation of the buffer layer forming composition, the urethane acrylate oligomer (UA-2), 40 parts by mass of isobornyl acrylate (IBXA), and 25 parts by mass of phenylhydroxypropyl acrylate (HPPA) were changed to 35 parts by mass. Except for this, an adhesive tape was obtained in the same manner as in Example 1.

[0298] [Example 3]

[0299] In the preparation of the buffer layer-forming composition, an adhesive tape was obtained in the same manner as in Example 2 except that the urethane acrylate oligomer (UA-2) was changed to 25 parts by mass and the isobornyl acrylate (IBXA) was changed to 50 parts by mass.

[0300] [Example 4]

[0301] In the synthesis of the urethane acrylate oligomer of the buffer layer, a urethane acrylate oligomer (UA-3) having a weight average molecular weight (Mw) of about 10,000 was obtained. In the preparation of the buffer layer forming composition, the composition was changed to 40 parts by mass of the urethane acrylate oligomer (UA-3), 40 parts by mass of isobornyl acrylate (IBXA) and 20 parts by mass of phenylhydroxypropyl acrylate (HPPA). Except for this, an adhesive tape was obtained in the same manner as in Example 1.

[0302] [Example 5]

[0303] An adhesive tape was obtained in the same manner as in Example 1 except that the substrate was changed to a low-density polyolefin film (thickness: 25 μm, Young's modulus at 23° C.: 380 MPa) and no buffer layer was provided.

[0304] [Example 6]

[0305] An adhesive tape was obtained in the same manner as in Example 1 except that the cushion layer was not provided.

[0306] [Comparative Example 1]

[0307] In the preparation of the buffer layer forming composition, an adhesive tape was obtained in the same manner as in Example 1 except that 30 parts by mass of the urethane acrylate oligomer (UA-3), 50 parts by mass of isobornyl acrylate (IBXA) and 20 parts by mass of phenylhydroxypropyl acrylate (HPPA) were used.

[0308] [Comparative Example 2]

[0309] In the preparation of the buffer layer forming composition, the adhesive tape was obtained in the same manner as in Example 1 except that 30 parts by mass of the urethane acrylate oligomer (UA-2) was used, and 20 parts by mass of tetrahydrofurfuryl acrylate (THFA) and 50 parts by mass of 4-acryloylmorpholine (ACMO) were added instead of isobornyl acrylate (IBXA) and phenylhydroxypropyl acrylate (HPPA).

[0310]

[0311] According to the above results, the semiconductor processing adhesive tape of the present invention can reduce the generation of tape scraps. In the manufacturing process of semiconductor devices, the adhesive sheet that generates a large amount of tape scraps is more likely to crack and break. Therefore, it can be seen that when the adhesive tape of the present invention is used, the productivity of semiconductor devices is excellent.

[0312] Description of Reference Numerals

[0313] 10: adhesive sheet; 11: substrate; 12: buffer layer; 13: adhesive layer; 20: adhesive sheet; 21: substrate.

Claims

1. An adhesive tape for semiconductor processing, comprising a substrate, a buffer layer provided on at least one side of the substrate, and an adhesive layer provided on the other side of the substrate, wherein: The breaking energy of the buffer layer at 23°C is 13-80 MJ / m 3 , The buffer layer is a cured product of a buffer layer-forming composition containing an energy-ray polymerizable compound, wherein the buffer layer-forming composition containing an energy-ray polymerizable compound is composed of 10 to 70% by weight of a urethane (meth) acrylate a1, 10 to 80% by weight of a polymerizable compound a2 having an alicyclic group or a heterocyclic group having 6 to 20 ring atoms, 5 to 40% by weight of a polymerizable compound a3 having a functional group, and a photopolymerization initiator. The weight average molecular weight of the urethane (meth)acrylate a1 is 20000 to 30000, and the thickness of the buffer layer is 1 to 100 μm. The polymerizable compound a3 having a functional group is a hydroxyl-containing (meth)acrylate having an aromatic ring.

2. The adhesive tape for semiconductor processing according to claim 1, wherein The Young's modulus of the substrate at 23° C. is 1000 MPa or more.

3. The adhesive tape for semiconductor processing according to claim 1 or 2, wherein: The thickness of the adhesive layer is less than 100 μm.

4. A method for manufacturing a semiconductor device, comprising the following steps: A step of attaching the adhesive tape for semiconductor processing according to any one of claims 1 to 3 to a surface of a semiconductor wafer, and cutting the adhesive tape along the outer circumference of the semiconductor wafer; A step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer; A step of grinding the semiconductor wafer having the adhesive tape attached to the surface and the groove or the modified region formed thereon from the back side, and singulating the semiconductor wafer into a plurality of chips using the groove or the modified region as a starting point; and A step of peeling the adhesive tape from the plurality of chips.

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