Protective tape and method for manufacturing semiconductor chip

Abstract

As a protective tape that has a base material and an adhesive layer and is used by being affixed to an adherend and a ring frame for supporting the adherend, provided is a protective tape that does not readily peel from the ring frame, is readily stretchable and has exceptional properties for following unevenness after the adhesive force of the adhesive layer is lowered, and does not readily allow the adhesive to remain on the adherend. A base material (2) is provided with a first resin layer (21) formed on a surface on the adhesive layer (3) side, and a second resin layer (22) formed on a surface of the first resin layer (21) opposite from the adhesive layer (3). The first resin layer (21) has a storage elastic modulus of 1.00-200 KPa at any temperature within the range of 50-90°C. The melting point of the second resin layer (22) is 80-230°C as measured by the DSC method. The thickness of the adhesive layer (3) is 20 μm or less, the adhesive force of the adhesive layer (3) with respect to stainless steel is 0.5 N / 25 mm or greater, and the Young's modulus of the entire tape is 1000 MPa or less.

Description

Protective tape and semiconductor chip manufacturing method

[0001] The present invention relates to a protective tape and a method for manufacturing a semiconductor chip using the same.

[0002] In a typical semiconductor chip manufacturing method, a large number of semiconductor chips are formed on a semiconductor wafer using photolithography and etching techniques, and then the semiconductor wafer is cut into multiple semiconductor chips by cutting the semiconductor wafer along cutting lines between each semiconductor chip. This cutting process is performed by placing the semiconductor wafer in a ring frame (a frame placed on the outside of the semiconductor wafer to support the semiconductor wafer) and affixing protective tape to the device-forming surface of the semiconductor wafer and the ring frame. After the cutting process, the adhesive strength of the protective tape is reduced by irradiating it with ultraviolet light, and then a process (pick-up process) is performed in which the semiconductor wafer is pushed from the protective tape side to remove the multiple semiconductor chips.

[0003] An example of a protective tape for this purpose is the adhesive film described in Patent Document 1. This adhesive film comprises a base layer, an intermediate layer, and an adhesive resin layer in this order, with the thickness X1 of the base layer being smaller than the thickness X2 of the intermediate layer, the storage modulus E' of the base layer at 85°C being 50 MPa or more and 10 GPa or less, and the storage modulus E' of the intermediate layer at 85°C being 1 MPa or more and less than 50 MPa. Specifically, it is described that the base layer is particularly preferably polyethylene naphthalate, and the intermediate layer is particularly preferably ethylene-vinyl acetate copolymer.

[0004] On the other hand, Patent Document 2 describes a tape for electronic components having at least one resin layer, the resin layer having a storage elasticity of 10,000 to 200,000 Pa at any temperature between 60°C and 80°C and a melt flow rate of 10 to 200 g / 10 min.

[0005] WO2020 / 203287 JP 2020-174063 A

[0006] However, the adhesive film described in Patent Document 1 has a hard substrate (substrate layer + intermediate layer) with poor deformability, making it difficult to stretch when attached to the element-forming surface of a semiconductor wafer via a ring frame, resulting in failure to adhere. Even if the film adheres successfully, it shrinks and peels off over time. Furthermore, even if the film is stretched to create distance between semiconductor chips during the pickup process, this is difficult because the substrate is difficult to stretch, and applying force to stretch the film causes the film to peel off from the ring frame. Furthermore, when bumps are formed on the elements of a semiconductor wafer, the surface of the semiconductor wafer on which the elements are formed has irregularities with a maximum height difference of 10 μm to 300 μm. However, the adhesive film described in Patent Document 1 still has room for improvement in terms of its ability to conform to such irregularities when attached to such an irregular surface.

[0007] Furthermore, in terms of adhesive strength, a thick adhesive layer is advantageous, as it improves ring frame retention and wafer retention during the cutting process, but if the adhesive layer is too thick, when applied to a surface with large unevenness (such as an uneven glass surface or a bumped surface of a semiconductor wafer), the adhesive may be pulled up and remain on the side of the adherend during the cutting process, or the individualized adherends (glass lenses or semiconductor chips) may be difficult to remove during the pick-up process, or the adhesive layer may break and remain on the adherend during the pick-up process.The electronic component tape described in Patent Document 2 is used in a processing method for electronic components in which the tape is applied to the circuit-formed surface of a semiconductor wafer, cut to the size of the semiconductor wafer, and then the surface of the semiconductor wafer opposite to the circuit-formed surface is ground.

[0008] The object of the present invention is to provide a protective tape having a substrate and an adhesive layer, which is used by being attached to an adherend and a ring frame, which is difficult to peel off from the ring frame, which is easy to stretch after the adhesive strength of the adhesive layer is reduced, which has excellent unevenness-following ability, and which does not easily leave adhesive residue on the adherend.

[0009] In order to solve the above-mentioned problems, one aspect of the present invention is a protective tape having a substrate and a pressure-sensitive adhesive layer, and being used by being attached to an adherend and a ring frame that supports the adherend, wherein the substrate comprises a first resin layer formed on the surface facing the pressure-sensitive adhesive layer, and a second resin layer formed on the surface of the first resin layer opposite the pressure-sensitive adhesive layer, the first resin layer having a storage modulus of 1.00 KPa or more and 200 KPa or less at any temperature in the range of 50°C or more and 90°C or less, the second resin layer having a melting point measured by a DSC method of 80°C or more and 230°C or less, the pressure-sensitive adhesive layer having a thickness of 20 μm or less, the pressure-sensitive adhesive layer having an adhesive strength to stainless steel of 0.5 N / 25 mm or more, and the protective tape having a Young's modulus of 1000 MPa or less for the entire tape during use (with the separator removed, if any).

[0010] The protective tape of the present invention has specified thickness of the adhesive layer and adhesive strength to stainless steel (which serves as an indicator of adhesive strength to the ring frame) in addition to the first resin layer and second resin layer that make up the substrate and the physical properties of the entire tape when in use, and is therefore expected to be less likely to peel off from the ring frame, to be easy to stretch after the adhesive strength of the adhesive layer is reduced, to have excellent conformability to uneven surfaces, and to leave less adhesive residue on the adherend.

[0011] 1 is a cross-sectional view showing a protective tape corresponding to an embodiment of the present invention.

[0012] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the following embodiments, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0013] 1, the protective tape 1 of this embodiment is composed of a substrate 2, a pressure-sensitive adhesive layer 3, and a separator 4. The substrate 2 is composed of a first resin layer 21 formed on the surface facing the pressure-sensitive adhesive layer 3, and a second resin layer 22 formed on the surface of the first resin layer 21 opposite the pressure-sensitive adhesive layer 3. The first resin layer 21 and the second resin layer 22 are in contact with each other.

[0014] The first resin layer 21 has a storage modulus of 1.00 KPa to 200 KPa at any temperature in the range of 50°C to 90°C (e.g., 50°C, 70°C, 80°C, 90°C). A preferred range for this storage modulus is 1.00 KPa to 200 KPa, a more preferred range is 10 KPa to 180 KPa, and a particularly preferred range is 40 KPa to 160 KPa. The second resin layer 22 has a melting point of 80°C to 230°C measured by DSC at a temperature rise rate of 1°C / min. A preferred range for the melting point of the second resin layer 22 is 80°C to 180°C, and a particularly preferred range is 80°C to 150°C.

[0015] The resin constituting the second resin layer 22 is preferably any one of EVA (ethylene vinyl acetate copolymer), α-olefin resin, LDPE (low density polyethylene), HDPE (high density polyethylene), PP (polypropylene), PP / SEPS (polypropylene / styrene-hydrogenated isoprene-styrene block copolymer), and COC (cyclic olefin copolymer). The Young's modulus of the protective tape 1 when the separator 4 is peeled off, that is, the Young's modulus of the entire tape during use, is 1000 MPa or less. The Young's modulus of the entire tape is preferably in the range of 30 MPa to 1000 MPa, more preferably 30 MPa to 950 MPa, even more preferably 30 MPa to 500 MPa, and particularly preferably 30 MPa to 200 MPa.

[0016] The thickness of the first resin layer 21 is, for example, preferably 100 μm or more and 500 μm or less, more preferably 150 μm or more and 400 μm or less, and even more preferably 200 μm or more and 350 μm or less. The thickness of the second resin layer 22 is, for example, preferably 30 μm or more and 150 μm or less, more preferably 40 μm or more and 120 μm or less, and even more preferably 50 μm or more and 100 μm or less. The second resin layer 22 is preferably thinner than the first resin layer 21. The thickness ratio of the first resin layer 21 to the second resin layer 22, expressed as "thickness of the first resin layer 21 / thickness of the second resin layer 22," is preferably 2.0 or more and 5.0 or less, more preferably 2.5 or more and 4.0 or less, and even more preferably 2.5 or more and 3.5 or less.

[0017] The thickness of the adhesive layer 3 is 20 μm or less. The thickness of the adhesive layer 3 is, for example, 5 μm or more and 20 μm or less. The thickness of the adhesive layer 3 is preferably 5 μm or more and 15 μm or less, and more preferably 5 μm or more and 10 μm or less. The adhesive strength of the adhesive layer 3 to stainless steel, which is an indicator of the adhesive strength to the ring frame, is 0.5 N / 25 mm or more. The adhesive strength of the adhesive layer 3 to stainless steel is preferably 0.5 N / 25 mm or more and 10 N / 25 mm or less, and more preferably 0.5 N / 25 mm or more and 5 N / 25 mm or less.

[0018] [Method of Manufacturing Protective Tape] The protective tape 1 can be manufactured, for example, by the following method. First, a thermoplastic resin, which is the material for forming the first resin layer 21, and a thermoplastic resin, which is the material for forming the second resin layer 22, are placed in extruders, respectively, and co-extruded. This results in the substrate 2 being obtained as a co-extruded film. Alternatively, the first resin layer 21 is prepared, and the thermoplastic resin, which is the material for forming the second resin layer 22, is extruded in a layered form onto one side of the first resin layer 21, and then cooled. This results in the substrate 2 being obtained as an extrusion laminate film. Next, a pressure-sensitive adhesive is applied to one side of the separator 4 to form a pressure-sensitive adhesive layer 3, thereby obtaining a separator with a pressure-sensitive adhesive layer. Next, the separator with a pressure-sensitive adhesive layer is bonded to the first resin layer 21 of the substrate 2, with the pressure-sensitive adhesive layer 3 facing the first resin layer 21, and the pressure-sensitive adhesive layer 3 is transferred to the first resin layer 21.

[0019] [Functions and Effects of Protective Tape] In the protective tape 1 of this embodiment, the substrate 2 is composed of a first resin layer 21 having a storage modulus of 1.00 KPa or more and 200 KPa or less at any temperature in the range of 50°C or more and 90°C or less, and a second resin layer 22 having a melting point measured by DSC method of 80°C or more and 230°C or less, and the Young's modulus of the entire tape during use is 1000 MPa or less. In addition, the thickness of the pressure-sensitive adhesive layer 3 is 20 μm or less, and the adhesive strength of the pressure-sensitive adhesive layer 3 to stainless steel is 0.5 N / 25 mm or more. As a result, the protective tape 1 of this embodiment exhibits the following functions and effects.

[0020] The protective tape 1 has a Young's modulus of 1000 MPa or less throughout the entire tape during use, which provides excellent deformability and allows it to be easily attached to the element-forming surface of the semiconductor wafer, which is the adherend, and to the ring frame. Furthermore, since the protective tape 1 is easily stretched, it can be stretched during the pickup process to create distance between the semiconductor chips. If the Young's modulus is less than 30 MPa, the protective tape may be too easily deformed and may stretch out when heat is applied, so the Young's modulus is preferably 30 MPa or more and 1000 MPa or less.

[0021] Furthermore, since the storage modulus of the first resin layer 21 is 200 KPa or less, the substrate 2 has excellent conformability to irregularities, so that the protective tape 1 can be neatly attached even when bumps are formed on the semiconductor wafer elements, resulting in an irregular surface with a maximum height difference of 10 μm to 300 μm on the surface of the semiconductor wafer on which the elements are formed (the surface of the adherend). In this case, the thickness of the first resin layer 21 is preferably set to a dimension in the range of not less than this maximum value but not more than 10 times this value. Similarly, since the substrate 2 has excellent conformability to irregularities, the protective tape 1 can be neatly attached even when used by being attached to a glass surface (the surface of the adherend on which multiple glass lenses are formed on a single glass plate) with an irregular surface with a maximum height difference of 10 μm to 300 μm.

[0022] If the storage modulus of the first resin layer is less than 1.00 KPa, the state of the protective tape may become unstable (for example, when the protective tape is transported in a stacked state, the first resin layer may protrude, causing adjacent protective tapes in the stacking direction to be bonded to each other). In addition, if the melting point of the second resin layer 22 is 80°C or higher and 230°C or lower, the Young's modulus of the entire tape during use can be 30 MPa or higher and 1000 MPa or lower.

[0023] If the melting point of the second resin layer exceeds 230°C, the Young's modulus of the entire tape during use will greatly exceed 1000 MPa, making it difficult to deform, and therefore the protective tape will not be able to be properly attached to the element formation surface of the semiconductor wafer and the ring frame. Also, if the melting point of the second resin layer is less than 80°C, the melting point of the second resin layer is likely to be lower than the temperature inside the device used, and there is a risk that the second resin layer will melt during use and stick to the device.

[0024] Furthermore, since the adhesive strength of the adhesive layer 3 to stainless steel is 0.5 N / 25 mm or more, the protective tape 1 is unlikely to peel off from the ring frame, and since the thickness of the adhesive layer 3 is 20 μm or less, adhesive residue on the adherend is unlikely to remain after the pick-up step. Therefore, the protective tape 1 of this embodiment is suitable for use in a semiconductor chip manufacturing method that includes a step of attaching a semiconductor wafer (adherend) to a ring frame (a frame that supports the outer edge of the adherend), and a step (dicing step) of cutting the semiconductor wafer into multiple semiconductor chips after this step.

[0025] The protective tape 1 of this embodiment is also suitable for use in the semiconductor chip manufacturing method, which includes, after the dicing step, a step of reducing the adhesive strength of the adhesive layer, and, after this step, a step of pushing the semiconductor wafer from the protective tape side to remove multiple semiconductor chips (pick-up step).The protective tape 1 of this embodiment is also suitable for use in the semiconductor chip manufacturing method, which includes, after the dicing step, a step of transporting the ring frame and multiple semiconductor chips with the protective tape attached.The protective tape 1 of this embodiment is also suitable for use in the semiconductor chip manufacturing method, which includes, after the transporting step, a step of reducing the adhesive strength of the adhesive layer, and, after the adhesive strength reduction step, a step of pushing the semiconductor wafer from the protective tape side to remove multiple semiconductor chips.

[0026] Furthermore, the protective tape 1 of this embodiment can also be suitably used in the following methods (a) to (d) for manufacturing devices other than semiconductor chips. (a): A method comprising the steps of attaching an adherend to a ring frame that supports the adherend, and, after this step, cutting the adherend into multiple pieces by making slits in the adherend from the side opposite the protective tape. (b): Method (a), including the steps of reducing the adhesive strength of the adhesive layer after the cutting into individual pieces, and, after this step, pushing the adherend from the protective tape side to remove the multiple pieces. (c): Method (a), including the steps of transporting the ring frame and the multiple pieces with the protective tape still attached after the cutting into individual pieces. (d): Method (c), including the steps of reducing the adhesive strength of the adhesive layer after the transporting step, and, after the adhesive strength reduction step, pushing the adherend from the protective tape side to remove the multiple pieces.

[0027] [Preparation of Pressure-Sensitive Adhesive Composition for Forming Pressure-Sensitive Adhesive Layer] A mixed solution of 446.5 g of 2-ethylhexyl acrylate, 45 g of methyl methacrylate, 80.0 g of methacrylic acid, and 0.5 g of benzoyl peroxide as a polymerization initiator was added dropwise to 400 g of toluene as a solvent over 2 hours, while allowing the mixture to react at 100° C. for 4 hours, thereby obtaining a solution of a first copolymer. To the obtained solution of the first copolymer, 105.3 g of 2-hydroxyethyl methacrylate and 0.1 g of hydroquinone as a polymerization inhibitor were added, and the mixture was allowed to react at 120° C. for 6 hours, followed by neutralization with acetic acid, thereby obtaining a solution of a second copolymer.

[0028] To the obtained solution of the second copolymer, polyisocyanate ("Coronate L (trade name)" manufactured by Nippon Polyurethane Industry Co., Ltd.) and photopolymerization initiator ("Irgacure 184 (trade name)" manufactured by Nippon Ciba-Geigy Ltd.) were added and mixed in a mass ratio of second copolymer:polyisocyanate:photopolymerization initiator = 100:0.5 (A), 1.5 (B), 2.0 (C):0.5 to prepare UV-curable pressure-sensitive adhesive compositions A, B, and C. In other words, pressure-sensitive adhesive compositions A, B, and C are the same except for the polyisocyanate content.

[0029] [Preparation of Resins Constituting First Resin Layer] <Measurement of Storage Modulus> Test samples were prepared by punching out 300 μm thick films made of the following resins A to E into disks with a diameter of 8 mm, and each test sample was sandwiched between parallel plates and operated using a viscoelasticity measuring device (manufactured by Rheometrics Scientific F.E., Inc., product name: ARES) at a measurement frequency of 0.1 to 10 Hz and a set temperature of 23° C. From the obtained data showing viscoelasticity, the dynamic shear storage modulus G' at 70° C. was determined, and this value was taken as the measured value of the storage modulus.

[0030] <Resin A> An ethylene-butyl acrylate copolymer (EBA) having a butyl acrylate content of 30% and a weight average molecular weight of 100,000 was prepared as Resin A. The storage modulus of Resin A at 70°C measured by the above method was 9.0 × 10 4 The viscosity was 90 kPa, the MFR was 30 g / 10 min, and the molecular weight distribution was 5.8.

[0031] <Resin B> An ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content of 40% and a weight average molecular weight of 40,000 was prepared as Resin B. The storage modulus of Resin B at 70°C measured by the above method was 4.0 × 10 4 The viscosity was 40 kPa, the MFR was 70 g / 10 min, and the molecular weight distribution was 6.5.

[0032] <Resin C> An α-olefin resin having a density of 0.89 and a weight average molecular weight of 40,000 was prepared as Resin C. The storage modulus of Resin C at 70°C measured by the above method was 1.6 × 10 5 The viscosity was 160 kPa, the MFR was 40 g / 10 min, and the molecular weight distribution was 2.4.

[0033] <Resin D> An ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content of 42% and a weight average molecular weight of 40,000 was prepared as Resin D. The storage modulus of Resin D at 70°C measured by the above method was 900 Pa (0.90 KPa), the MFR was 70 g / 10 min, and the molecular weight distribution was 6.5.

[0034] <Resin E> An α-olefin resin having a density of 0.90 and a weight average molecular weight of 40,000 was prepared as Resin E. The storage modulus of Resin E at 70°C measured by the above method was 2.2 × 10 5 The viscosity was 220 kPa, the MFR was 40 g / 10 min, and the molecular weight distribution was 2.0.

[0035] [Preparation of Resin Constituting Second Resin Layer] <HDPE> "Nipolon Hard 2500" manufactured by Tosoh Corporation was prepared as high-density polyethylene (HDPE). <α-Olefin Resin> "Kernel (trademark) KS260" manufactured by Japan Polyethylene Co., Ltd. was prepared as α-olefin resin (polyα-olefin). This resin is a metallocene-based olefin resin with a DSC melting point of 92°C, a Shore A hardness of 90, and a density of 0.902 g / cm. 3<PP / SEPS mixed resin (elastomer)> "J-105G" manufactured by Ube Industries, Ltd. was prepared as a homopolypropylene (PP) resin, and "Hybler (registered trademark) 7125" manufactured by Kuraray Co., Ltd. was prepared as a styrene-hydrogenated isoprene-styrene block copolymer (SEPS). These resins were mixed in a mass ratio of 50:50 to obtain a PP / SEPS mixed resin.

[0036] <LDPE> "Petrothene (registered trademark) 231F" manufactured by Tosoh Corporation was prepared as low-density polyethylene (LDPE). <EVA> "Ultrathene (registered trademark) 640" manufactured by Tosoh Corporation was prepared as ethylene vinyl acetate copolymer (EVA). <COC> "TOPASS (registered trademark) 8007F-600" manufactured by Polyplastics Co., Ltd. was prepared as cyclic olefin copolymer (COC).

[0037] [Production of Protective Tape] [Example 1] A protective tape 1 having the configuration shown in Fig. 1 was produced as follows. First, the HDPE and the resin A were placed in separate extruders and co-extruded to produce a substrate 2 in which a first resin layer 21 made of the resin A and having a thickness of 300 µm was formed on a second resin layer 22 made of the HDPE and having a thickness of 120 µm. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite to the second resin layer 22).

[0038] Next, the pressure-sensitive adhesive composition A was applied to a separator 4 made of polyethylene terephthalate (PET) with a thickness of 40 μm so that the film thickness after drying would be 10 μm, and the coating was dried to form a pressure-sensitive adhesive layer 3. This resulted in a separator 4 with a pressure-sensitive adhesive layer 3. Next, the separator 4 with a pressure-sensitive adhesive layer 3 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21, thereby transferring the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, the protective tape 1 of Example 1 was obtained. From the protective tape 1 of Example 1 from which the separator 4 had been removed, a test specimen was prepared in accordance with JIS K7127, "Test Method for Tensile Properties of Plastic Films and Sheets with a Thickness of 1 mm or Less." A tensile test was performed using this test specimen to measure the Young's modulus. This test was performed using five test specimens, and the average value was defined as the "Young's modulus of the entire tape" of the protective tape 1 of Example 1.

[0039] Example 2 A protective tape 1 having the configuration shown in FIG. 1 was produced as follows. First, the α-olefin resin and the resin B were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin B on a 100 μm-thick second resin layer 22 made of the α-olefin resin. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was used to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape 1 of Example 2 was obtained. The "Young's modulus of the entire tape" of the protective tape 1 of Example 2 was measured in the same manner as in Example 1.

[0040] Example 3 A protective tape 1 having the configuration shown in FIG. 1 was prepared as follows. First, a substrate 2 was prepared using the same method as in Example 2, in which a 300 μm-thick first resin layer 21 made of the resin B was formed on a 100 μm-thick second resin layer 22 made of the α-olefin resin. Corona treatment was then performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, PSA composition A was applied to a 40 μm-thick separator 4 made of polyethylene terephthalate (PET) to a dry thickness of 20 μm, and the coating was dried to form a PSA layer 3. This resulted in a separator 4 with PSA layer 3. The resulting separator 4 with PSA layer 3 was then bonded to the first resin layer 21 of the substrate 2, with the PSA layer 3 facing the first resin layer 21. The same method as in Example 1 was then performed to transfer the PSA layer 3 to the first resin layer 21. In this manner, a protective tape 1 of Example 3 was obtained. In addition, the "Young's modulus of the entire tape" of the protective tape 1 of Example 3 was measured using the same method as in Example 1.

[0041] Example 4 A protective tape 1 having the configuration shown in FIG. 1 was prepared as follows. First, a substrate 2 was prepared using the same method as in Example 2, in which a 300 μm-thick first resin layer 21 made of the resin B was formed on a 100 μm-thick second resin layer 22 made of the α-olefin resin. Corona treatment was then performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, pressure-sensitive adhesive composition B was applied to a 40 μm-thick separator 4 made of polyethylene terephthalate (PET) to a dry thickness of 5 μm, and the coating was dried to form a pressure-sensitive adhesive layer 3. This resulted in a separator 4 with a pressure-sensitive adhesive layer 3. The resulting separator 4 with a pressure-sensitive adhesive layer 3 was then bonded to the first resin layer 21 of the substrate 2, with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was then performed to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape 1 of Example 4 was obtained. In addition, the "Young's modulus of the entire tape" of the protective tape 1 of Example 4 was measured using the same method as in Example 1.

[0042] Example 5 A protective tape 1 having the configuration shown in FIG. 1 was produced as follows. First, the PP / SEPS and the resin C were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin C formed on a 100 μm-thick second resin layer 22 made of the PP / SEPS. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was used to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape 1 of Example 3 was obtained. The "Young's modulus of the entire tape" of the protective tape 1 of Example 5 was measured in the same manner as in Example 1.

[0043] Example 6 A protective tape 1 having the configuration shown in FIG. 1 was produced as follows. First, the LDPE and the resin C were placed in separate extruders and co-extruded to produce a substrate 2 having a first resin layer 21 of the resin C and a thickness of 300 μm formed on a second resin layer 22 of the LDPE and a thickness of 300 μm. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was bonded to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21, and the pressure-sensitive adhesive layer 3 was transferred to the first resin layer 21 by performing the same method as in Example 1. In this way, a protective tape 1 of Example 4 was obtained. The "Young's modulus of the entire tape" of the protective tape 1 of Example 6 was measured in the same manner as in Example 1.

[0044] Comparative Example 1 First, the HDPE and Resin D were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of Resin D on a 100 μm-thick second resin layer 22 made of HDPE. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was used to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape of Comparative Example 1 was obtained. The "Young's modulus of the entire tape" of the protective tape of Comparative Example 1 was measured in the same manner as in Example 1.

[0045] Comparative Example 2 First, the HDPE and the resin E were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin E on a 100 μm-thick second resin layer 22 made of the HDPE. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was then performed to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape of Comparative Example 2 was obtained. The "Young's modulus of the entire tape" of the protective tape of Comparative Example 2 was measured in the same manner as in Example 1.

[0046] Comparative Example 3 First, the EVA and the resin C were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin C on top of a 100 μm-thick second resin layer 22 made of the EVA. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same procedure as in Example 1 was followed to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this way, a protective tape of Comparative Example 3 was obtained. The "Young's modulus of the entire tape" of the protective tape of Comparative Example 3 was measured in the same manner as in Example 1.

[0047] [Comparative Example 4] First, the COC and the resin C were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin C on a 100 μm-thick second resin layer 22 made of the COC. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same procedure as in Example 1 was followed to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this way, a protective tape of Comparative Example 4 was obtained. The "Young's modulus of the entire tape" of the protective tape of Comparative Example 4 was measured in the same manner as in Example 1.

[0048] Comparative Example 5 First, the resin C was extrusion laminated to a thickness of 300 μm onto a 50 μm-thick polyethylene terephthalate (PET) film. This produced a substrate 2 in which a 300 μm-thick first resin layer 21 made of the resin C was formed on a second resin layer 22 made of PET. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, a separator 4 with a pressure-sensitive adhesive layer 3 obtained in the same manner as in Example 1 was attached to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21, and the pressure-sensitive adhesive layer 3 was transferred to the first resin layer 21 by performing the same method as in Example 1. In this way, a protective tape of Comparative Example 5 was obtained. The "Young's modulus of the entire tape" of the protective tape of Comparative Example 5 was measured in the same manner as in Example 1.

[0049] Comparative Example 6 First, the HDPE and the resin C were placed in separate extruders and co-extruded to produce a substrate 2 having a 300 μm-thick first resin layer 21 made of the resin C on a 120 μm-thick second resin layer 22 made of the HDPE. Next, a corona treatment was performed on the upper surface of the first resin layer 21 (the surface opposite the second resin layer 22). Next, the pressure-sensitive adhesive composition A was applied to a 40 μm-thick separator 4 made of polyethylene terephthalate (PET) to a dry thickness of 30 μm, and the coating was dried to form a pressure-sensitive adhesive layer 3. This resulted in a separator 4 with a pressure-sensitive adhesive layer 3. The resulting separator 4 with a pressure-sensitive adhesive layer 3 was then bonded to the first resin layer 21 of the substrate 2 with the pressure-sensitive adhesive layer 3 facing the first resin layer 21. The same method as in Example 1 was then performed to transfer the pressure-sensitive adhesive layer 3 to the first resin layer 21. In this manner, a protective tape of Comparative Example 6 was obtained. In addition, the "Young's modulus of the entire tape" of the protective tape of Comparative Example 6 was measured in the same manner as in Example 1.

[0050] [Comparative Example 7] The pressure-sensitive adhesive composition C was applied to a separator 4 made of polyethylene terephthalate (PET) with a thickness of 40 μm so that the film thickness after drying would be 5 μm, and the coating film was dried to form a pressure-sensitive adhesive layer 3. In this way, a separator 4 with a pressure-sensitive adhesive layer 3 was obtained. A protective tape of Comparative Example 7 was obtained in the same manner as in Comparative Example 6, except that the separator 4 with a pressure-sensitive adhesive layer 3 obtained in this manner was used. In addition, the "Young's modulus of the entire tape" of the protective tape of Comparative Example 7 was measured in the same manner as in Example 1.

[0051] [Measurement of Adhesion Strength of Adhesive Layer] The adhesive strength of the protective tapes obtained in Examples 1 to 6 and Comparative Examples 1 to 7 to SUS304 was measured using a method based on JIS Z 0237. Specifically, the method is as follows. First, three test pieces measuring 25 mm wide x 300 mm long were taken from each protective tape. Next, a 2.0 mm thick SUS304 steel plate was polished with #280 waterproof abrasive paper. Each test piece was placed on the polished surface with the adhesive layer side facing down, and a 2 kg rubber roller was rolled back and forth three times on each test piece to press each test piece onto the SUS304 steel plate. After leaving the test pieces for one hour after pressing, the adhesive strength of each test piece was measured using a tensile tester ("Strograph VE10 (product name)" manufactured by Toyo Seiki Seisaku-sho, Ltd.) conforming to JIS B 7721, with measurements falling within the range of 15 to 85% of its capacity. Measurements were performed by the 90° peeling method at a pulling rate of 50 mm / min, at 23° C. and a relative humidity of 49%, and the average value of three test pieces for each protective tape was calculated and used as the adhesive strength.

[0052] [Performance Evaluation] The performance of the protective tapes obtained in Examples 1 to 6 and Comparative Examples 1 to 7 was examined as follows.

[0053] <Vacuum Mounting Performance> A semiconductor wafer having a diameter of 200 mm (8 inches), bumps of 200 μm height and 400 μm pitch, a scribe width of 100 μm, and 5 mm square semiconductor chips formed on its surface was prepared. This semiconductor wafer was placed on a table heated to 70°C of a vacuum laminator (manufactured by Omiya Kogyo Co., Ltd., product name OVM-1200MSH), and a ring frame with each protective tape attached was set on top of it. It was then examined whether the protective tape could be attached to the element-forming surface of the semiconductor wafer under vacuum using the vacuum laminator. When the protective tape was attached, it was evaluated as having good vacuum mounting performance and marked with "◯." When the protective tape was not attached, it was evaluated as having poor vacuum mounting performance and marked with "X."

[0054] <Conformability> For the protective tapes that could be attached under vacuum conditions in the above test, the conformability of the protective tape to the semiconductor wafer was visually observed after 22 hours. Those that showed lifting at the bump portion from the attached surface of the semiconductor wafer were evaluated as defective with an "x"; those that showed lifting only at the scribed portion were evaluated as acceptable with an "o"; and those that showed no lifting were evaluated as good with an "◎".

[0055] <Expandability> Only those specimens that exhibited good vacuum mounting performance were subjected to a test to examine expandability using the following method. First, a bare wafer with a diameter of 150 mm (6 inches) and a thickness of 350 μm and a ring frame of a size corresponding to the bare wafer were prepared. Next, this bare wafer was attached to the ring frame using each protective tape and set in a die picker (Canon Machinery Inc., product name CAP-3000II). After setting, the outer peripheral portion (outer edge) of the ring frame to which each protective tape was attached was fixed, and the table of the central portion (wafer portion) was pushed up to expand the specimen by an expansion amount of 2 mm. If the tape did not peel off during expansion, the expandability was evaluated as good, with a "◯"; if the protective tape peeled off from the ring frame, the expandability was evaluated as poor, with a "X".

[0056] <Ring Frame Retention> First, a ring frame cassette was prepared, which is a container for storing multiple ring frames and has a structure that allows each ring frame to be held individually and horizontally. A silicon bare wafer having a diameter of 200 mm (8 inches) and a thickness of 725 μm was attached to an 8-inch ring frame using each protective tape (each test specimen differing only in the protective tape), and the wafer was placed in the ring frame cassette with the tape side facing downward and the wafer side facing upward. Note that the attachment using each protective tape was performed under the same conditions (manually using a roller). Two hours after storing each test specimen in the ring frame cassette, the condition of the protective tape was visually confirmed. A test specimen was evaluated as "poor" (×) if the protective tape had fallen off the ring frame; "pass" (◯) if the protective tape had not fallen off the ring frame but some peeling had occurred; and "particularly good" (◎) if there was no peeling of the protective tape at all.

[0057] <State of the peeled surface (the surface from which the protective tape was peeled)> Only those protective tapes for which the tracking ability and ring frame retention were good (◯ or ⊚) were subjected to a test to examine the state of the peeled surface (the surface from which the protective tape was peeled) by the following method. First, after visually observing each protective tape in the tracking evaluation described above, ultraviolet light (wavelength 365 nm) was irradiated from the substrate side at an integrated dose of 200 mJ / mm 2 The adhesive strength of the adhesive layer was reduced by irradiating the sample with light at 1000 W. Next, using a tensile tester ("Strograph VE10 (trade name)" manufactured by Toyo Seiki Seisakusho Co., Ltd.), the protective tape on the ring frame was grasped and peeled off in accordance with "10.4.1 Method 1: 180-degree peel adhesion to test plate" of "10.4 Measurement of peel adhesion" in JIS Z 0237 (2009). The pulling speed was 300 mm / min.

[0058] The semiconductor wafer surface (the surface to be peeled) from which the protective tape had been peeled was then observed under an optical microscope to determine whether any adhesive remained on the semiconductor wafer surface. The adhesive remained in bulk or whisker form. Cases where adhesive remained on the bumps on the semiconductor wafer surface were rated as poor (×), cases where adhesive remained in parts other than the bumps (such as scribe lines) were rated as acceptable for practical use (◯), and cases where no adhesive remained on the semiconductor wafer surface at all were rated as particularly good (◎).

[0059] <Stability> If there was a risk that adjacent protective tapes in the stacking direction would stick to each other when transported in a stacked state, or that the protective tapes would melt and stick to the inside of the device when the temperature inside the device used was high, the rating was "X", and if there was no such risk, the rating was "O".

[0060] <Overall Evaluation> When all performances were rated as "good" or "double circle", the overall evaluation was deemed good and rated as "good", and when any performance was rated as "poor", the overall evaluation was deemed as "poor". These results are shown in Table 1 below along with the configuration of each protective tape. Note that "-" in Table 1 indicates that the corresponding performance test was not conducted. Note that with regard to stability, Comparative Examples 1 and 3 were rated as poor, and the reasons for this are as follows.

[0061] In the protective tape of Comparative Example 1, the storage modulus of the first resin layer at 70°C is less than 1.00 KPa, so that when transported in a stacked state, the first resin layer may protrude, causing adjacent protective tapes in the stacking direction to be bonded together. In the protective tape of Comparative Example 3, the melting point of the second resin layer is 75°C, so that when the temperature inside the device used is 75°C or higher, there is a risk that the tape will melt and stick to the device during use.

[0062]

[0063] From the results in Table 1, it can be seen that the protective tapes of Examples 1 to 6 have a storage modulus of the first resin layer 21 at 70°C of 40 KPa or more and 160 KPa or less, a melting point of the second resin layer 22 measured by the DSC method of 83°C or more and 128°C or less, a Young's modulus of the entire tape during use of 35 MPa or more and 950 MPa or less, a thickness of the first resin layer 21 that is 1.5 times (300 μm) the maximum height difference of the unevenness on the semiconductor wafer surface (200 μm), a thickness of the adhesive layer 3 that is 5 μm or more and 20 μm or less, and an adhesive strength of the adhesive layer 3 to stainless steel of 0.6 N / 25 mm or more, and therefore are excellent in all respects of vacuum mounting performance, followability, expandability, ring frame retention, state of the peeled surface, and stability.

[0064] In contrast, the protective tape of Comparative Example 1 was excellent in vacuum mounting performance, conformability, expandability, ring frame retention, and the state of the peeled surface, but had poor stability as described above because the storage modulus of the first resin layer at 70°C was less than 1.00 KPa. The protective tape of Comparative Example 2 was excellent in vacuum mounting performance, expandability, ring frame retention, and stability, but had poor conformability because the storage modulus of the first resin layer at 70°C was more than 200 KPa.

[0065] The protective tape of Comparative Example 3 had excellent ring frame retention, but because the melting point of the second resin layer measured by the DSC method was less than 80°C, the stability was poor as described above, and because the Young's modulus of the entire tape during use was less than 30 MPa, it stretched too much when applied with a vacuum laminator and could not be applied. The protective tape of Comparative Example 4 had excellent vacuum mounting performance, conformability, ring frame retention, the state of the peeled surface, and stability, but because the Young's modulus of the entire tape during use was more than 1000 MPa, the expandability was poor.

[0066] The protective tape of Comparative Example 5 had a melting point of the second resin layer measured by DSC above 230°C, resulting in a Young's modulus of 3650 MPa for the entire tape during use, significantly exceeding 1000 MPa. Therefore, it was unable to deform and adhere when applied using a vacuum laminator. The protective tape of Comparative Example 6 had excellent vacuum mounting performance, conformability, expandability, ring frame retention, and stability, but the thickness of the adhesive layer 3 was too thick at 30 μm, leaving adhesive residue on the adherend surface, resulting in poor condition of the peeled surface. The protective tape of Comparative Example 7 had excellent vacuum mounting performance, conformability, expandability, and stability, but the adhesive strength of the adhesive layer 3 to stainless steel was insufficient at 0.4 N / 25 mm, resulting in poor ring frame retention.

[0067] REFERENCE SIGNS LIST 1 protective tape 2 substrate 3 adhesive layer 4 separator 21 first resin layer 22 second resin layer

Claims

1. A protective tape having a substrate and an adhesive layer, the protective tape being attached to an adherend and a ring frame supporting the adherend, the substrate comprising a first resin layer formed on the surface facing the adhesive layer, and a second resin layer formed on the surface of the first resin layer opposite the adhesive layer, the first resin layer having a storage modulus of 1.00 KPa or more and 200 KPa or less at any temperature in the range of 50°C or more and 90°C or less, the second resin layer having a melting point of 80°C or more and 230°C or less as measured by a DSC method, the adhesive layer having a thickness of 20 μm or less, the adhesive strength of the adhesive layer to stainless steel being 0.5 N / 25 mm or more, and the Young's modulus of the entire tape during use being 1000 MPa or less.

2. The protective tape according to claim 1, wherein the Young's modulus of the entire tape during use is 30 MPa or more and 1000 MPa or less.

3. The protective tape according to claim 1, wherein the first resin layer and the second resin layer are in contact with each other.

4. The protective tape according to claim 1, wherein the protective tape is attached to an uneven surface of the adherend, and the maximum height difference of the unevenness is 10 μm or more and 300 μm or less.

5. The protective tape according to claim 4, wherein the thickness of said first resin layer is within a range of a value equal to or greater than the maximum height difference of said projections and recesses and up to 10 times the maximum height difference.

6. The protective tape according to claim 1, wherein the resin constituting the second resin layer is any one of EVA (ethylene vinyl acetate copolymer), α-olefin resin, LDPE (low density polyethylene), HDPE (high density polyethylene), PP (polypropylene), PP / SEPS (polypropylene / styrene-hydrogenated isoprene-styrene block copolymer), and COC (cyclic olefin copolymer).

7. The protective tape according to claim 4, wherein the adherend is glass.

8. The protective tape according to claim 4, wherein the adherend is a semiconductor wafer.

9. A method for manufacturing semiconductor chips, comprising the steps of: attaching the protective tape according to claim 1 to the semiconductor wafer and the ring frame, which are the substrates; and, after the attaching step, cutting the semiconductor wafer from the side opposite the protective tape to cut the semiconductor wafer into a plurality of semiconductor chips.

10. A method for manufacturing semiconductor chips as described in claim 9, comprising: a step of reducing the adhesive strength of the adhesive layer after the cutting step; and a step of pushing the semiconductor wafer from the protective tape side to remove the multiple semiconductor chips after the cutting step.

11. The method of manufacturing semiconductor chips according to claim 9, further comprising the step of transporting the ring frame and the plurality of semiconductor chips with the protective tape attached thereto, after the cutting step.

12. A method for manufacturing semiconductor chips as described in claim 11, comprising: a step of reducing the adhesive strength of the adhesive layer after the transporting step; and a step of pushing the semiconductor wafer from the protective tape side to remove the multiple semiconductor chips after the reducing adhesive strength step.

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