Back grind tape and method for manufacturing the same

Abstract

To give heat resistance and wettability to a cushion layer, and enable coating formation of an antistatic layer composed of a water-based antistatic agent.SOLUTION: In a back grind tape in which an adhesive layer 12 to which a semiconductor wafer is stuck is provided on a cushion layer 14 supported on a base material 13 through a coating antistatic layer 15, the cushion layer 14 is composed of two layers. The one layer is a cushioning adhesive layer 16 positioned on the side of the base material 13, and the other layer is a cushioning film layer 17 positioned on the side of the antistatic layer 15. The cushioning film layer 17 is formed of a thermoplastic resin film 17a modified by irradiation with an electron beam, wettability and heat resistance are enhanced, coating of a coating agent at the time of coating for forming an antistatic layer is enabled, and the cushioning adhesive layer 16 is protected from dry heat.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a backgrinding tape used in the backgrinding process in semiconductor manufacturing. [Background technology]

[0002] The backgrind tape is used to protect the surface of the semiconductor wafer and to fix the semiconductor wafer in place. In the backgrind process, the backgrind tape attached to the surface of the semiconductor wafer is held by a vacuum chuck and the back surface of the semiconductor wafer is polished. The polishing is performed while cooling with running water.

[0003] The backgrind tape used in this type of process may have bump electrodes formed on the surface of the semiconductor wafer, so it is required to be able to properly conform to the unevenness of the bumps to provide excellent fixation to the semiconductor wafer and to prevent the infiltration of grinding water.

[0004] An example of a backgrind tape with irregularity-following properties is disclosed in Patent Document 1 below. This backgrind tape comprises, in this order, a base layer, an irregularity-absorbing layer made of polyethylene or the like, an antistatic layer, and an adhesive resin layer that is attached to a semiconductor wafer. Since the antistatic layer is close to the surface of the adhesive resin layer, it is able to exhibit antistatic properties.

[0005] In the manufacturing process, first, the unevenness absorbing layer is formed on one side of the base layer by extrusion lamination, while a conductive material is applied and dried on a separately prepared release film to form an antistatic layer. Next, the antistatic layer is laminated on the unevenness absorbing layer, and then an adhesive coating liquid is applied on the antistatic layer and dried to form an adhesive resin layer. The reason for forming the antistatic layer separately and then laminating it on the unevenness absorbing layer in this manner is believed to be due to the fact that the material used for the unevenness absorbing layer is a material with low heat resistance and wettability, such as polyethylene. This is because if the heat resistance of the unevenness absorbing layer is low, it cannot withstand the heat during drying when the antistatic layer is directly laminated by coating, and if the wettability is low, problems such as repellency occur when the antistatic layer is directly coated by coating.

[0006] In other words, even if an attempt is made to directly coat a conductive material, particularly a water-based material, on the irregularity-absorbing layer, problems arise due to the properties of the irregularity-absorbing layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-6540 A Summary of the Invention [Problem to be solved by the invention]

[0008] The main object of this invention is to provide a cushion layer with heat resistance and wettability that enable the coating and formation of an antistatic layer. [Means for solving the problem]

[0009] To this end, the present invention provides the following backgrind tape.

[0010] That is, the backgrind tape has an adhesive layer to be attached to a semiconductor wafer, which is provided on a cushion layer supported by a substrate via a coated antistatic layer, and the cushion layer is made up of two layers: a cushioning adhesive layer located on the substrate side and a cushioning film layer located on the antistatic layer side, and the backgrind tape has a cushioning film layer formed of a thermoplastic resin film modified by electron beam irradiation.

[0011] In this configuration, the cushioning adhesive layer located on the substrate side of the cushioning layer absorbs the unevenness of the semiconductor wafer surface and supports the cushioning film layer on the antistatic layer side. The cushioning film layer covering the cushioning adhesive layer has the ability to absorb unevenness, but is also improved in heat resistance and wettability by modification through electron beam irradiation, allowing sufficient application of the coating agent during coating to form the antistatic layer, and protecting the cushioning adhesive layer from drying heat. The antistatic layer provides antistatic protection behind the adhesive layer. Effect of the Invention

[0012] According to this invention, the cushioning adhesive layer is covered with a cushioning film layer with improved heat resistance and wettability. Therefore, the coating agent for the antistatic layer can be directly applied onto the cushioning film layer and dried. As a result, the cushioning adhesive layer is not damaged, and the required antistatic properties can be obtained while obtaining the desired cushioning properties. In particular, since the antistatic layer can be directly formed by coating, a water-based antistatic agent with excellent antistatic properties can be used, thereby improving the antistatic properties. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic diagram showing a cross-sectional structure of a backgrind tape. [Diagram 2] FIG. [Diagram 3] FIG. 11 is an explanatory diagram showing another example of an outline of the manufacturing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be described below with reference to the drawings.

[0015] The cross-sectional view of FIG. 1 shows a schematic configuration of the backgrind tape 11. The backgrind tape 11 has an adhesive layer 12 that is attached to the surface of a semiconductor wafer (not shown) during backgrinding to polish the back surface of the semiconductor wafer. The adhesive layer 12 is provided on a cushion layer 14 supported by a substrate 13 via a coated antistatic layer 15. That is, the backgrind tape 11 is composed of the substrate 13, the cushion layer 14 on one side of the substrate 13, the antistatic layer 15 on the cushion layer 14 (the surface opposite the substrate 13), and the adhesive layer 12 on the antistatic layer 15 (the surface opposite the cushion layer 14). The antistatic layer 15 is intended to prevent charging when the backgrind tape 11 is peeled off from the semiconductor wafer.

[0016] The antistatic layer 15 is formed by coating directly on the cushion layer 14. Therefore, the cushion layer 14 is composed of two layers, a cushioning adhesive layer 16 located on the substrate 13 side and a cushioning film layer 17 located on the antistatic layer 15 side, and the cushioning film layer 17 is formed of a thermoplastic resin film modified (crosslinked) by electron beam irradiation. The cushioning adhesive layer 16 and the cushioning film layer 17 are in close contact with each other and have high integrity.

[0017] Each layer of the backgrind tape having such a general configuration will now be described.

[0018] <Base material> The substrate 13 functions as a support in the backgrind tape 11 and is formed of a sheet-like thermoplastic resin. Examples of the thermoplastic resin include the following: polyolefin (polyethylene, polypropylene, poly(4-methyl-1-pentene), poly(1-butene), etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polyamide (nylon-6, nylon-66, polymetaxylene adipamide, etc.), poly(meth)acrylate, polyvinyl chloride, polyetherimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, polysulfone, polyethersulfone, polyphenylene ether, and one or more selected from these. Among these, polyethylene terephthalate (PET) is particularly suitable because of its versatility, high heat resistance, and dimensional stability, and easy processing.

[0019] Additives may be added to the thermoplastic resin, and examples of the additives include lubricants, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, colorants, organic or inorganic fillers, and the like.

[0020] The surface of the base material 13 on which the cushion layer 14 is to be laminated may be subjected to a surface treatment such as a corona treatment, a plasma treatment, or an anchor coat treatment for the purpose of fixation.

[0021] The thickness of the base material 13 is preferably set in the range of 12 μm to 500 μm. If it is too thin, wrinkles are likely to occur during manufacturing and the support capacity for the semiconductor wafer will be insufficient during the back-grinding process. If it is too thick, handling during the back-grinding process will be poor.

[0022] <Cushioning adhesive layer> The cushion layer 14 is a layer for absorbing unevenness on the surface of the semiconductor wafer, and the cushioning adhesive layer 16 constituting the lower layer (substrate side) of the cushion layer 14 is composed of a resin component having a cross-linked structure so as to have sufficient cushioning properties. The cushioning adhesive layer 16 in this example is made of an adhesive having a cross-linked structure.

[0023] The adhesive can be any commonly used adhesive, and in addition to the adhesive polymer, a hardener is blended if the adhesive requires a hardener for crosslinking. The adhesive polymer can be, for example, an acrylic, rubber, urethane, or silicone type. Among these, the acrylic type is particularly preferred, as it is highly versatile and easy to control the elastic modulus, etc.

[0024] The curing agent can be selected from isocyanate-based, epoxy-based, and metal chelate-based agents according to the adhesive. Of these, isocyanate-based agents are preferred because of their versatility.

[0025] Additives may be added to the adhesive, and examples of the additives include plasticizers, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, and colorants.

[0026] The thickness of the cushioning adhesive layer 16 depends on the size of the irregularities on the semiconductor wafer on which it is to be used, but is preferably set within the range of 5 μm to 300 μm.

[0027] Regarding the cushioning properties of the cushioning adhesive layer 16, its storage modulus (G') at the temperature at which it is applied to the semiconductor wafer should be about 0.01 to 0.10 MPa at 1 Hz. If the storage modulus is too high, the cushioning properties and ability to conform to the unevenness of the bumps will be insufficient, causing gaps between the semiconductor wafer and the layer, which will cause contamination during back grinding. Conversely, if the storage modulus is too low, the layer will be too soft and will not be able to support the semiconductor wafer during polishing.

[0028] <Cushioning film layer> The cushioning film layer 17 constituting the upper layer (on the antistatic layer 15 side) of the cushioning layer 14 is made of a resin film having a cross-linked structure so as to have the necessary cushioning properties. The cushioning film layer 17 in this example is made of a thermoplastic resin having a cross-linked structure.

[0029] Examples of thermoplastic resins include the following: olefin resins, ethylene-polar monomer copolymers, ABS resins, vinyl chloride resins, vinylidene chloride resins, (meth)acrylic resins, polyamide resins, fluorine resins, polycarbonate resins, polyester resins, ionomer resins, etc., and one or more selected from these. Among these, polyethylene and ethylene-polar monomer copolymers are particularly suitable. This is because they have good cushioning properties and are easily crosslinked by electron beams.

[0030] Additives may be added to the thermoplastic resin, and examples of the additives include plasticizers, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, and colorants.

[0031] The thickness of the cushioning film layer 17 depends on the size of the irregularities on the semiconductor wafer on which it is used, but is preferably set within the range of 10 μm to 250 μm.

[0032] Regarding the cushioning properties of the cushioning film layer 17, its storage modulus (G') at the temperature at which it is attached to the semiconductor wafer should be about 1 to 500 MPa at 1 Hz. If the storage modulus is too high, the cushioning properties and ability to conform to the unevenness of the bumps will be insufficient, causing gaps between the semiconductor wafer and the film, which will cause contamination during back grinding. Conversely, if it is too low, the film will be too soft and will not be able to support the semiconductor wafer during polishing.

[0033] <Cushioning layer> The thickness of the cushion layer 14 consisting of the cushion adhesive layer 16 and the cushion film layer 17 must be at least twice the height of the bumps on the semiconductor wafer to which it is to be used, and is set in the range of 20 μm to 500 μm.

[0034] <Antistatic Layer> The antistatic layer 15 is made of a commonly used antistatic coating material. In particular, it is made by applying a water-based antistatic coating material. Examples of water-based antistatic coating materials include surfactants, ionic liquids, and conductive carbon materials, and the conductive polymer PEDOT·PSS is the most suitable. This is because it can reduce the surface resistivity. In addition, LDPE (low density polyethylene), which can be preferably used for the cushioning film layer, has low solvent resistance, so if a solvent-based material is directly applied, problems such as swelling may occur.

[0035] The thickness of the antistatic layer 15 is set in the range of 0.01 μm to 10 μm, preferably about 0.1 μm to 1 μm.

[0036] Regarding the antistatic properties of the antistatic layer 15, the surface resistivity of the antistatic layer 15 alone is preferably less than 1.0E+06 [Ω / □], and more preferably less than 1.0E+04 [Ω / □]. This measured value is the value in a state in which the layer is coated on a PET film.

[0037] The surface resistivity is measured using Hiresta-UX MCP-HT800 (manufactured by Nitto Seiko Analytech) in accordance with JIS K6911. The measurement conditions are an applied voltage of 100 V and a test time of 30 seconds.

[0038] <Adhesive layer> The adhesive layer 12 is made of an adhesive coating material made of an adhesive. In addition to an adhesive polymer, the adhesive coating material contains a hardener if the adhesive requires a hardener for crosslinking. In addition, an antistatic agent is added.

[0039] The adhesive may be either a non-curing adhesive or a curing adhesive, but a curing adhesive, particularly an active energy ray curing adhesive, is preferable. This is because it can suppress adhesive residue when peeled off from the semiconductor wafer after the back grinding process. The active energy ray curing adhesive is preferably selected from those in which a functional group that reacts with active energy rays is introduced into the adhesive polymer, those in which a compound that crosslinks with active energy rays such as polyfunctional (meth)acrylate is blended into the main agent, or those containing both of these. The functional group that reacts with active energy rays includes radically polymerizable unsaturated groups, (meth)acrylic groups, allyl groups, vinyl groups, etc. Among them, (meth)acrylic groups are particularly preferable because they can be reacted by blending a photopolymerization initiator and irradiating ultraviolet rays.

[0040] The adhesive polymer is preferably an acrylic polymer because it is versatile and easy to introduce a radically polymerizable unsaturated group.

[0041] A reactive ionic liquid is preferably used as the antistatic agent. This is because it is less likely to bleed out or transfer components to the surface to which it is attached. Examples of reactive functional groups that ionic liquids have include hydroxyl groups, isocyanate groups, (meth)acrylic groups, allyl groups, vinyl groups, and thiol groups. It is more preferable to have two or more of these functional groups.

[0042] Additives may be added to the adhesive coating material, and examples of the additives that can be suitably selected include photopolymerization initiators, compounds that undergo crosslinking reactions when exposed to active energy rays, plasticizers, processing aids, fillers, stabilizers, antibacterial agents, flame retardants, and colorants.

[0043] The thickness of the adhesive layer 12 is about 3 μm to 30 μm, and preferably 5 μm to 15 μm. If it is too thin, sufficient adhesive strength cannot be obtained, and if it exceeds 30 μm, it becomes difficult to peel off.

[0044] The adhesive strength of the adhesive layer 12 is set so that it can be firmly and reliably attached to the semiconductor wafer. In the case of using a curable adhesive, the adhesive layer is designed to have a sufficient initial adhesive strength as described above, and to have an adhesive strength that is reduced to a level that allows easy peeling from the semiconductor wafer by irradiation with active energy rays such as ultraviolet rays after processing.

[0045] <others> The antistatic properties of the entire backgrind tape are such that the surface resistivity after ultraviolet irradiation is less than 1.0E+10 [Ω / □], and more preferably less than 1.0E+09 [Ω / □].

[0046] The surface resistivity is measured in the same manner as described above, using Hiresta-UX MCP-HT800 (manufactured by Nitto Seiko Analytech Co., Ltd.) in accordance with JIS K6911. The measurement conditions are an applied voltage of 100 V and a test time of 30 seconds.

[0047] A release film (not shown) for protecting the adhesive layer 12 may be provided on the adhesive layer 12. The release film may be a film having releasability (such as PTFE) or a film that has been subjected to a release treatment (such as PET with a silicone release treatment).

[0048] <Manufacturing method> A method for producing the backgrind tape 11 having the above-mentioned structure will now be described.

[0049] As shown in Fig. 2, the method for producing the backgrind tape 11 includes, in order, cushion layer forming steps (b, c, d), an antistatic agent coating step (f), and an adhesive layer forming step (g). The cushion layer forming steps (b, c, d) are steps for forming a cushion layer 14 on one side of the substrate 13. The antistatic agent coating step (f) is a step for forming an antistatic layer 15 on the cushion layer 14. The adhesive layer forming step (g) is a step for forming an adhesive layer 12 on the antistatic layer 15.

[0050] Among the above steps, the cushion layer forming steps (b, c, d) are composed of a first cushion layer forming step (b) and a second cushion layer forming step (d). In the first cushion layer forming step (b), a cushioning adhesive layer 16 made of an adhesive is formed on the substrate 13. In the second cushion layer forming step (d), a cushioning film layer 17 made of a thermoplastic resin film 17a modified by electron beam irradiation is formed on the cushioning adhesive layer 16. The cushioning adhesive layer 16 made of an adhesive in the first cushion layer forming step (b) is formed by applying a coating agent. The cushioning film layer 17 made of a thermoplastic film in the second cushion layer forming step (d) is formed by lamination.

[0051] The above "thermoplastic resin film modified by electron beam irradiation" indicates that modification of the thermoplastic resin film 17a by electron beam irradiation may be performed before lamination, after lamination, or both before and after lamination.

[0052] Specifically, a coating agent for forming the cushioning adhesive layer 16 is applied, i.e., coated and dried, on a predetermined substrate (a) to form the cushioning adhesive layer 16 (b). The coating can be performed by an appropriate method such as a general bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. The same applies below.

[0053] While the cushioning adhesive layer 16 is formed, the thermoplastic resin film 17a is irradiated with an electron beam EB to modify (crosslink) (c). The polymer chains constituting the thermoplastic resin film 17a are crosslinked by the irradiation with the electron beam EB, improving the heat resistance. The conditions for the irradiation with the electron beam EB are, for example, an acceleration voltage of 30 kV to 250 kV and a dose of 25 kGy to 300 kGy. If the acceleration voltage is lower than about 30 kV, the electron beam may not reach the film sufficiently, and if it is higher than 250 kV, the polymer may deteriorate. Also, if the dose is lower than 25 kGy, crosslinking may be insufficient, and if it is higher than 300 kGy, heat wrinkles may easily occur.

[0054] The electron beam irradiated thermoplastic resin film 17a is laminated onto the cushioning adhesive layer 16 (d), thereby forming the cushioning film layer 17 (e).

[0055] Next, the antistatic layer 15 is formed by coating on the cushioning film layer 17 (f). That is, a coating agent for forming the antistatic layer 15 is applied on the cushioning film layer 17 and dried.

[0056] Finally, the adhesive layer 12 is formed on the antistatic layer 15 (g). That is, the coating material for forming the adhesive layer is applied (applied and dried) onto the antistatic layer 15. At this time, the cushioning film layer 17 modified by electron beam irradiation has high wettability and heat resistance. Due to its high wettability, the cushioning film layer 17 does not repel the coating material when it is applied, allowing a sufficient amount of coating material to be applied. Furthermore, due to its high heat resistance, the cushioning film layer 17 protects the cushioning adhesive layer 16 from the drying heat during the coating process to form the antistatic layer 15.

[0057] The cushioning adhesive layer 16 and the adhesive layer 12 may be formed separately on a release liner and then laminated by transfer or the like.

[0058] The modification by electron beam irradiation can be carried out before lamination as described above, or after lamination, or both before and after lamination.

[0059] Furthermore, the antistatic agent coating step (f) may be performed within the cushion layer forming step (b, c, d). That is, as shown in FIG. 3, in the cushion layer forming step (b, c, d), the thermoplastic resin film 17a is irradiated with an electron beam EB to modify (crosslink) (c), and then the antistatic layer 15 is coated and formed on the modified cushion film layer 17 (f). Meanwhile, a coating agent for forming the cushion adhesive layer 16 is coated on the substrate (a) to form the cushion adhesive layer 16 (b). Then, the cushion film layer 17 is laminated on the cushion adhesive layer 16 (d). This forms the cushion layer 14 with the antistatic layer 15 (e). Finally, the adhesive layer 12 is formed on the antistatic layer 15 (g).

[0060] In this way, by carrying out the antistatic agent coating step after the modification and before lamination to the cushioning adhesive layer 16, only the cushioning film layer 17 can be exposed to high temperatures during drying to form the antistatic layer 15. In other words, since the base material 13 and the cushioning layer 14 have different thermal expansion coefficients, if high temperatures are applied to them at the same time, the cushioning layer 14 will stretch while the base material 13 will not stretch very much. For this reason, when the temperature returns to normal, the cushioning layer 14 may shrink and cause undesirable curling, but this inconvenience can be reduced or avoided.

[0061] When the backgrind tape 11 constructed as described above is applied to the surface of a semiconductor wafer while being heated, the cushion layer absorbs the unevenness of the bumps on the surface of the semiconductor wafer, ensuring reliable application by the adhesive layer.

[0062] After the backgrinding process is completed, ultraviolet light is applied to facilitate peeling off of the backgrind tape 11. At this time, the antistatic layer 15 below the adhesive layer 12 functions to make the antistatic properties of the entire backgrind tape 11 less than 1.0E+10 [Ω / □] (surface resistivity after ultraviolet light irradiation), thereby suppressing peeling electrification.

[0063] In this way, the required antistatic properties can be obtained while still obtaining the desired cushioning properties.

[0064] Moreover, since the antistatic layer 15 uses a water-based antistatic agent having excellent antistatic properties, high antistatic properties are obtained.

[0065] An embodiment will be described below.

[0066] [Example 1] <Base material> The substrate used was a PET film (S-105, manufactured by Toray Industries, Inc.) having a thickness of 50 μm.

[0067] <Cushioning adhesive layer> The coating material for forming the cushioning adhesive layer was prepared as follows: 100 parts of acrylic adhesive (KP-1079, manufactured by Nippon Carbide Industries Co., Ltd.), 2 parts of isocyanate curing agent (CK-101, manufactured by Nippon Carbide Industries Co., Ltd.), and 30 parts of toluene were weighed and mixed.

[0068] <Cushioning film layer> The thermoplastic resin film constituting the cushioning film layer was an LDPE film (GF-1, manufactured by Tamapoly Corporation) having a thickness of 50 μm.

[0069] <Antistatic Layer> To form the antistatic layer, a conductive polymer (NAS conductive liquid C2010, manufactured by Nagaoka Sangyo Co., Ltd.) was used as an antistatic agent.

[0070] <Adhesive layer> Coating agent A for forming the adhesive layer was prepared as follows: 100 parts of ultraviolet-reactive acrylic adhesive coating agent (N-9578, manufactured by Mitsubishi Chemical Corporation), 2.8 parts of isocyanate curing agent (CAT-10L, manufactured by Toyo-Morton Co., Ltd.), 1 part of ionic liquid, and 1.4 parts of photopolymerization initiator (Omnirad184, manufactured by IGM Resins BV) were weighed and mixed.

[0071] <Manufacture> In the manufacturing process, first, a cushioning adhesive layer was formed on a substrate by coating. That is, the above-mentioned coating material for the cushioning adhesive layer was applied and dried. At this time, the thickness of the cushioning adhesive layer was set to 50 μm.

[0072] Next, a cushioning film layer was formed by irradiating the LDPE film with an electron beam at an acceleration voltage of 80 kV and a dose of 150 kGy.

[0073] Then, the electron beam irradiated surface of the electron beam irradiated LDPE film was laminated onto the dried cushioning adhesive layer to form a cushioning film layer.

[0074] Thereafter, the above-mentioned antistatic agent was applied and dried to give an antistatic layer having a thickness of 0.5 μm.

[0075] Finally, the coating material for forming the adhesive layer described above was applied to a 38 μm-thick release film (PK1130 manufactured by Lintec Corporation) and dried to obtain an adhesive layer with a thickness of 10 μm, which was then laminated to the antistatic layer described above.

[0076] [Comparative Example 1] The preparation was carried out in the same manner as in Example 1, except that no antistatic layer was provided.

[0077] [Comparative Example 2] The same procedure as in Example 1 was repeated, except that the cushioning film layer was not irradiated with electron beams.

[0078] [Comparative Example 3] The same procedure as in Example 1 was repeated except that the cushioning film layer was not irradiated with electron beams and no antistatic layer was provided.

[0079] [Comparative Example 4] The adhesive layer was produced in the same manner as in Example 1, except that coating agent B, which did not contain an ionic liquid, was used to form the adhesive layer.

[0080] Coating material B for forming the adhesive layer was prepared as follows: 100 parts of ultraviolet-reactive acrylic adhesive coating material (N-9578, manufactured by Mitsubishi Chemical Corporation), 1.1 parts of isocyanate curing agent (CAT-10L, manufactured by Toyo-Morton Co., Ltd.), and 1.4 parts of photopolymerization initiator (Omnirad184, manufactured by IGM Resins BV) were weighed and mixed.

[0081] The configurations of the backgrind tapes of the examples and comparative examples are shown in Table 1.

[0082] [Table 1] To evaluate the performance of each backgrind tape, tests were conducted on two items: adhesion between the cushioning adhesive layer and the cushioning film layer, and the wettability of the cushioning film layer.

[0083] <Adhesion between the cushioning adhesive layer and the cushioning film layer> In order to confirm whether the cushioning adhesive layer and the cushioning film layer were in close contact with each other, a peel test was carried out. The test method is as follows. The cushioning film layer side of the three-layered product consisting of a substrate, a cushioning adhesive layer, and a cushioning film layer was attached to a SUS plate with double-sided tape. In this state, the substrate was peeled off 180 degrees and the state of peeling was observed. ◯: When the substrate was peeled off, material destruction occurred, and it was confirmed that the substrate was firmly adhered. ×: When the substrate was peeled off, peeling was observed between the cushioning adhesive layer and the cushioning film layer.

[0084] <Wettability> This test was for evaluating the coatability of an antistatic agent on a cushioning film layer, and evaluation was performed according to the following criteria when the antistatic agent was applied. ◯: No repelling of the antistatic agent occurred from immediately after coating until after drying. ×: Repelling of the antistatic agent occurred immediately after coating and after drying.

[0085] In addition, the adhesive strength of the adhesive layer and the surface resistivity of the entire backgrind tape were measured. The adhesive strength was measured based on the adhesive tape test method of JIS Z 0237. The surface resistivity was measured in the same manner as described above.

[0086] As seen in Table 1, even when electron beam irradiation is performed to form the cushioning film layer, the adhesion between the cushioning adhesive layer and the cushioning film layer is good (Example 1, Comparative Example 1, Comparative Example 4). It is also found that electron beam irradiation improves the wettability of the antistatic agent, making it possible to process the antistatic layer (Example 1, Comparative Example 2, Comparative Example 4). Without electron beam irradiation, the adhesion between the cushioning adhesive layer and the cushioning film layer is poor (Comparative Example 2, Comparative Example 3), and the wettability is also poor (Comparative Example 3).

[0087] In the case of Example 1, the adhesion between the cushioning adhesive layer and the cushioning film layer and the wettability of the cushioning film layer are good, and the adhesive strength is 5.4 [N / 25mm] before UV irradiation, i.e., the initial adhesive strength, and 0.2 [N / 25mm] after UV irradiation, which shows that the necessary adhesive strength is obtained and that the adhesive strength is sufficiently reduced by UV irradiation. The surface resistivity after UV irradiation is 4.1E+08 [Ω / □], which is less than 1.0E+10 [Ω / □] in the previous example and less than 1.0E+09 [Ω / □], and good performance is obtained.

[0088] In this way, the cushioning layer is composed of a cushioning adhesive layer and a cushioning film layer, and the cushioning film layer located on the antistatic layer side is formed of a thermoplastic resin film modified by electron beam irradiation. This allows the antistatic layer to be close to the adhesive layer, and it is found that a useful, high-performance backgrind tape can be obtained.

[0089] In particular, since the antistatic layer is formed using a water-based antistatic coating agent, high antistatic properties can be obtained.

[0090] In addition, if the thermoplastic resin film that will become the cushioning film layer is irradiated with electron beams alone during the manufacturing process and then laminated to the cushioning adhesive layer, it is possible to minimize the occurrence of problems such as curling caused by electron beam irradiation, thereby producing a backgrind tape of higher quality.

[0091] In addition, a comparison between Example 1 and Comparative Example 4 shows that by mixing an ionic liquid into the coating material that constitutes the adhesive layer, the surface resistivity can be more reliably reduced, resulting in high antistatic properties. [Explanation of symbols]

[0092] 11…Back grind tape 12...adhesive layer 13...Base material 14…Cushion layer 15...Antistatic layer 16...Cushioning adhesive layer 17…Cushioning film layer 17a…Thermoplastic resin film EB…Electron beam

Claims

1. A backgrind tape having an adhesive layer to be attached to a semiconductor wafer, the adhesive layer being provided on a cushion layer supported by a substrate via an antistatic coating layer, the cushion layer is composed of two layers, a cushion adhesive layer located on the substrate side and a cushion film layer located on the antistatic layer side, The cushioning film layer is formed of a thermoplastic resin film modified by electron beam irradiation. Backgrind tape.

2. The antistatic layer is made of a water-based antistatic coating material. The backgrind tape of claim 1.

3. The thermoplastic resin film is made of polyethylene or an ethylene-polar monomer copolymer, or contains at least one of them. The backgrind tape according to claim 1 or 2.

4. A method for producing a backgrind tape, comprising the steps of: providing an adhesive layer for attaching a semiconductor wafer on a cushion layer supported on a substrate, with an antistatic coating layer interposed therebetween; a cushion layer forming step of forming the cushion layer on one surface of the base material; an antistatic agent coating step of forming the antistatic layer on the cushion layer; An adhesive layer forming step of forming an adhesive layer on the antistatic layer, The cushion layer forming step is composed of a first cushion layer forming step of forming a cushion adhesive layer made of an adhesive on the base material, and a second cushion layer forming step of forming a cushion film layer made of a thermoplastic resin film modified by electron beam irradiation on the cushion adhesive layer formed in the first cushion layer forming step. Backgrind tape manufacturing method.

5. The cushioning film layer to be laminated in the second cushioning layer forming step is irradiated with an electron beam alone, and then laminated to the cushioning adhesive layer.

5. The method for producing a backgrind tape according to claim 4.

6. The antistatic agent coating step is carried out within the cushion layer forming step.

6. The method for producing a backgrind tape according to claim 4 or 5.

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