Base material film for dicing sheet

Abstract

Provided is a base material film for a dicing sheet. The base material film suppresses generation of cutting chips in a dicing process of a semiconductor wafer and has excellent blocking prevention properties. This base material film for a dicing sheet is characterized by being a multilayer film in which at least an A-layer, a B-layer, and a C-layer are arranged in the stated order, and is characterized in that the A-layer has a ten-point average roughness Rz of 1.5-15.0 µm, the B-layer contains a propylene-based copolymer in an amount of 85-99 mass% and an olefin-based thermoplastic elastomer in an amount of 1-15 mass%, and the C-layer contains an olefin-based thermoplastic elastomer.

Description

Substrate film for dicing sheets

[0001] The present invention relates to a substrate film for a dicing sheet, which is used to fix a semiconductor wafer when dicing a semiconductor wafer into chip shapes.

[0002] A known method for manufacturing semiconductor chips involves slicing a cylindrical single-crystal silicon ingot with a wire saw or similar tool, etching and polishing it, then dicing (cutting and separating) the resulting semiconductor wafers (approximately 12-inch or 8-inch in diameter) into chips. The diced chips are then moved to an expansion process where they are picked up. Furthermore, the picked-up chips are bonded to a glass epoxy substrate or lead frame, sealed together with a package sealing resin, and then the cured package is diced to obtain a packaged product.

[0003] A dicing sheet is used to fix semiconductor wafers and packages in the aforementioned dicing process.

[0004] A dicing sheet consists of an adhesive layer for fixing the semiconductor wafer or package and a resin layer that serves as a support. The resin layer used is a dicing sheet base film. Generally, after the dicing sheet base film is manufactured, the adhesive layer is processed in a later process, the film is wound into a roll, stored and transported as a dicing sheet, and then unwound from the roll at a dicing manufacturer for use.

[0005] In semiconductor chip manufacturing, the dicing process partially cuts the semiconductor wafer and package, as well as the adhesive layer and the substrate film for the dicing sheet (generally referred to as a half-cut). During this process, the impact and friction from the dicing blade generate cutting debris from the substrate film for the dicing sheet (thread-like or whisker-like debris generated from the film after dicing, also referred to as burrs or whiskers). This cutting debris can contaminate the wafer and package, potentially leading to a decrease in chip yield.

[0006] Furthermore, considering that these cutting chips can cause malfunctions in sensors and other equipment during semiconductor chip pickup, leading to reduced productivity, the characteristic of producing as little cutting chip as possible is required. However, cutting chips washed away by the cutting fluid during dicing are not a problem.

[0007] Furthermore, dicing sheets are typically manufactured, stored, and transported in rolls. Therefore, if the films become blocked, quality can deteriorate. In other words, even if a dicing sheet has excellent quality, problems can arise due to such blocking.

[0008] Therefore, with the primary objective of eliminating various problems in the dicing process, the picking process, and the storage and transportation of rolled materials, the following dicing sheet has been reported.

[0009] Patent Document 1 proposes a dicing substrate film in which the layer cut by the dicing blade is made of a resin composition containing a polymethylpentene resin, as a method for reducing cutting debris during the dicing process.

[0010] Patent Document 2 proposes a dicing sheet base film as a method for reducing cutting debris during the dicing process, wherein the layer cut by the dicing blade has an olefin-based thermoplastic elastomer, and the base layer contains low-density polyethylene, with the low-density polyethylene content being 50% to 100% by weight.

[0011] Patent Document 3 proposes a multilayer dicing substrate film as a method for reducing cutting debris during the dicing process. This substrate film contains a resin composition comprising 100 parts by weight of styrene-butadiene copolymer (SEBS) and 20 to 70 parts by weight of polypropylene resin (PP), and 10 to 100 parts by weight of olefin thermoplastic elastomer (TPO), with the layer cut by the dicing blade comprising 30 to 80 parts by weight of SEBS and 20 to 70 parts by weight of PP, and a base layer comprising a resin composition comprising 30 to 80 parts by weight of SEBS and 20 to 70 parts by weight of PP.

[0012] Japanese Patent Publication No. 2015-070092, Japanese Patent Publication No. 2020-019172, Japanese Patent Publication No. 2008-159701

[0013] However, the dicing substrate film described in Patent Document 1 has a problem in that a sufficient chip improvement effect cannot be obtained when the layer on the side cut by the dicing blade contains a polymethylpentene resin.

[0014] Furthermore, the dicing sheet base films described in Patent Documents 2 and 3 have the problem of generating cutting debris when the dicing blade cuts into the base layer.

[0015] Furthermore, the dicing sheet base film described in Patent Document 3 has the problem that blocking occurs on both sides of the base material, which worsens the processability of subsequent adhesive processing and other processes.

[0016] The present invention aims to provide a substrate film for dicing sheets that suppresses the generation of cutting debris during the dicing process of semiconductor wafers and also exhibits excellent blocking prevention properties.

[0017] The above objectives of the present invention have been achieved by the following inventions: 1. A laminated film in which at least layers A, B, and C are arranged in this order, wherein layer A has a ten-point average roughness Rz of 1.5 μm or more and 15.0 μm or less, layer B has a propylene copolymer content of 85% by mass or more and 99% by mass or less and contains 1% by mass or more and 15% by mass or less of olefin-based thermoplastic elastomer, and layer C contains an olefin-based thermoplastic elastomer, a base film for a dicing sheet. 2. The base film for a dicing sheet according to 1, wherein the olefin-based thermoplastic elastomer is a propylene-based elastomer. 3. The base film for a dicing sheet according to 1 or 2, wherein the resin hardness of layer C is 20 or more and 60 on the Shore D hardness scale. 4. The base film for a dicing sheet according to any one of 1 to 3, wherein layer A contains organic fine particles with an average particle diameter of 3 μm or more and 30 μm or less. 5. The base film for a dicing sheet according to 4, wherein the organic fine particles are polyethylene fine particles. 6. A dicing sheet substrate film according to any one of 1 to 5 above, wherein the C layer is subjected to flame treatment, plasma treatment, or corona treatment. 7. A dicing sheet substrate film according to any one of 1 to 6 above, wherein at least one side of the dicing sheet substrate film has a surface resistivity ρs1 (Ω / sq) at 23°C and 65% RH that satisfies formula (1).

[0018] 1.0 × 10 ７ Ω / sq≦ρs1≦1.0×10 １３ Ω / sq...Formula (1) 8. A dicing sheet base film according to any one of 1 to 7 above, wherein at least one side of the dicing sheet base film has a surface resistivity of ρs1 (Ω / sq) at 23°C and 65% RH, and the surface resistivity of ρs2 (Ω / sq) at 23°C and 65% RH after heating the dicing sheet base film at 80°C for 10 minutes satisfies formula (2).

[0019] 0.5≦(ρs2 / ρs1)≦1.5...Formula (3)

[0020] Since the generation of cutting chips in the dicing process is not a problem for the base film for a dicing sheet of the present invention, there is no concern about contamination of silicon chips or package products after the dicing process. Also, by setting the ten-point average roughness Rz of the surface of layer A within a specific range, blocking over time does not occur even when stored in a roll form.

[0021] The base film for a dicing sheet of the present invention is a laminated film in which at least layer A, layer B, and layer C (also referred to as a cut layer) are arranged in this order. Layer A has a ten-point average roughness Rz of 1.5 μm or more and 15.0 μm or less, layer B has a propylene-based copolymer content of 85% by mass to 99% by mass, and contains 1% by mass or more and 15% by mass or less of an olefin-based thermoplastic elastomer, and layer C is made of an olefin-based thermoplastic elastomer. By having such a layer structure, a base film for a dicing sheet with extremely excellent total balance can be obtained. That is, the generation of cutting chips in the dicing process can be suppressed, and the concern about blocking over time can be eliminated even when stored in a roll form.

[0022] The method for manufacturing the base film for a dicing sheet of the present invention is not particularly limited. For example, coextrusion molding, T-die molding, a method of laminating other layers on a layer obtained in advance by coextrusion molding, T-die molding, or inflation molding by a known lamination method such as extrusion lamination or extrusion coating, a method of laminating each obtained film by dry lamination after making each layer into an independent film, etc. can be mentioned. From the viewpoint of productivity, the coextrusion molding method of supplying each material of layer A, layer B, and layer C to a multi-layer extruder for molding is preferable, and from the viewpoint of thickness accuracy, the T-die molding method is more preferable.

[0023] When manufactured by co-extrusion molding, the components of layers A, B, and C are each extruded from a melt extruder. At this time, the upper limit of the resin extrusion temperature is preferably 240°C, more preferably 230°C, and even more preferably 220°C. If the resin extrusion temperature exceeds 240°C, thermal degradation of the resin may occur, and gel formation may be more likely. There is no particular lower limit for the resin extrusion temperature, but if the resin temperature is below 180°C, the melt viscosity may become too high, which may reduce productivity.

[0024] The dicing sheet substrate film of the present invention preferably has antistatic properties, in order to suppress the adhesion of dust and other particles due to static charge, thereby suppressing damage and product degradation due to static charge in semiconductor chips and devices manufactured using the dicing sheet substrate film of the present invention, and improving the product yield rate. Specifically, when the surface resistivity of the film at 23°C and 65% RH is ρs1 (Ω / sq), it is preferable that at least one side satisfies formula (1). That is, ρs1 is 1.0 × 10⁻⁶. ７ Ω / sq or more, 1.0×10 １３ It is preferable that the coefficient of static electricity is Ω / sq or less. ρs1 (Ω / sq) can be measured by the method described in the examples. From the viewpoint of improving antistatic properties, ρs1 should be 1.0 × 10⁻⁶. １２ Ω / sq or less is more preferable, and 1.0 × 10 １１ A ratio of Ω / sq or less is even more preferable, and 1.0 × 10 １０ A value of Ω / sq or less is particularly preferred. Furthermore, from the viewpoint of achieving both antistatic properties and other film properties and film quality, ρs1 should be 1.0 × 10⁻⁶. ８ A density of Ω / sq or higher is more preferable.

[0025] Furthermore, in order to exhibit stable antistatic properties regardless of the manufacturing method or usage environment, it is preferable that the dicing sheet base film of the present invention satisfies formula (2) above when the surface resistivity of the film, measured at 23°C and 65% RH after heating at 80°C for 10 minutes, is defined as ρs² (Ω / sq). That is, it is preferable that the ratio of ρs² to ρs1 (ρs² / ρs1) is 0.5 or more and 1.5 or less. ρs² (Ω / sq) can be measured by the method described in the examples.

[0026] As a method for controlling ρs1 (Ω / sq) of the base film for a dicing sheet of the present invention within the above-described preferred range, a method of incorporating an antistatic agent into the film can be mentioned. Examples of the antistatic agent used in the film of the present invention include low molecular weight antistatic agents such as surfactants, conductive particles such as carbon black, and polymer type antistatic agents. However, from the viewpoint of being difficult to bleed out to the surface of the film and being excellent in non-pollution, polymer type antistatic agents are more preferable. As the polymer type antistatic agent, known ones can be used, but in particular, at least one selected from the group consisting of polyether-polyolefin block copolymers, polyether ester amides, polyether amides, polyether amide imides, polyethylene glycol (meth)acrylate copolymers, ionomers, and polymers and ionic compounds (such as metal salts such as lithium salts) is preferable.

[0027] When incorporating an antistatic agent into the base film for a dicing sheet of the present invention, the antistatic agent may be incorporated into any layer of the film. However, from the viewpoint of suppressing peeling electrification when unwinding the base film for a dicing sheet of the present invention wound in a roll or a dicing tape provided with the base film for a dicing sheet of the present invention, and electrification due to friction in the use process, and also from the viewpoint of compatibility between antistatic properties and other film physical properties, film quality, productivity, and cost, a method of incorporating the antistatic agent into the layer with a smaller thickness in a film composed of two or more layers, or a method of incorporating the antistatic agent into at least one surface layer, or both surface layers of a film composed of three or more layers is more preferable.

[0028] The content of the above-described antistatic agent can be appropriately adjusted according to the desired surface resistivity. However, when the entire layer containing the antistatic agent is 100% by mass, the content of the antistatic agent in the layer is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. Also, similarly, from the viewpoint of compatibility with film physical properties and film quality other than productivity and antistatic properties, the content of the antistatic agent in the layer is preferably 40% by mass or less.

[0029] The details of each layer constituting the base film for the dicing sheet of the present invention are described below.

[0030] [Layer A] In the present invention, Layer A has a ten-point average roughness Rz of 1.5 μm or more and 15.0 μm or less. If the ten-point average roughness Rz of Layer A is less than 1.5 μm, it will stick (block) between Layer A and Layer C of the dicing sheet base film during storage and transportation in roll form, causing problems when unrolling the roll in the subsequent adhesive processing step. Also, if the ten-point average roughness Rz exceeds 15.0 μm, the flatness of the dicing sheet base film will decrease. The ten-point average roughness Rz is more preferably 3.0 to 12.0 μm, and particularly preferably 4.0 to 10.0 μm.

[0031] In this invention, in order to achieve a ten-point average roughness Rz of 1.5 μm or more and 15.0 μm or less, the surface of existing ethylene propylene rubber (EPR), polyethylene (PE)-containing block polypropylene (BPP), or ethylene propylene copolymer (EPC) may be roughened with inorganic particles, but it is preferable to use small-particle organic fine particles. Specific examples of organic fine particles include polyethylene, polystyrene, and polymethyl methacrylate fine particles, but polyethylene fine particles are more preferable. The average particle size of the organic fine particles is preferably 30 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably around 10 μm. By setting the average particle size of the organic fine particles to 30 μm or less, the surface of layer A becomes appropriately uneven, making it less likely to damage the contact surface and less likely for organic fine particles to fall off even when the resulting dicing sheet base film is manufactured and stored in a wound state. If the average particle size of the organic microparticles exceeds 30 μm, the flatness of the film after deposition may be poor due to the influence of coarse particles, and it may also cause foreign matter. The average particle size of the organic microparticles is preferably 3 μm or more, and more preferably 5 μm or more. By setting the average particle size of the organic microparticles to 3 μm or more, a blocking prevention effect over time can be obtained even when stored in roll form. If the average particle size of the organic microparticles is less than 3 μm, sufficient surface roughness cannot be obtained, and blocking may occur over time when stored in roll form.

[0032] In the present invention, the material of the A layer is not particularly limited. However, considering the compatibility with the B layer described later, it is preferably a polyolefin resin, and an ethylene homopolymer, a propylene homopolymer, an ethylene copolymer, and a propylene copolymer are preferably mentioned.

[0033] As the ethylene copolymer, low-density polyethylene, high-density polyethylene, and ethylene α-olefin copolymer are preferably mentioned.

[0034] As the ethylene / α-olefin copolymer, ethylene / (1-butene) copolymer, ethylene / (1-hexene) copolymer, and ethylene / (1-octene) copolymer are preferably mentioned.

[0035] As the propylene copolymer, a propylene / α-olefin block copolymer and a propylene / α-olefin random copolymer are preferably mentioned.

[0036] As the propylene / α-olefin block copolymer, a propylene / ethylene block copolymer is preferably mentioned.

[0037] As the propylene / α-olefin random copolymer, a propylene / ethylene random copolymer and a propylene / (1-butene) random copolymer are preferably mentioned. Among them, a propylene / ethylene random copolymer and a propylene / ethylene block copolymer are preferably mentioned, and a propylene / ethylene block copolymer is preferable because of its good laminating property with the B layer.

[0038] The density of the polypropylene copolymer is in the range of 0.89 to 0.920 g / cm ３ and the melt viscosity index (hereinafter abbreviated as MFR) is preferably in the range of 1 to 10 g / min (measured at 230 °C and 21.17 N) according to JIS K7161 (1994).

[0039] In addition to the preferred resin described above, it is preferable that the A layer of the present invention contains the aforementioned antistatic agent in order to reduce the surface resistivity of the A layer surface and suppress charging due to peeling and friction. The preferred antistatic agent for the A layer of the present invention and its content in the A layer are as described above. The thickness of the A layer is preferably 2 μm to 50 μm, more preferably 5 μm to 40 μm, and even more preferably 5 μm to 30 μm. By having the thickness of the A layer within this range, it is possible to provide a base film for dicing sheets with even better dicing properties.

[0040] [C layer] The C layer in this invention has an olefin-based thermoplastic elastomer. By using an olefin-based thermoplastic elastomer, cutting chips during dicing are suppressed.

[0041] Furthermore, olefin-based thermoplastic elastomers have improved thermal stability compared to other elastomer resins (e.g., styrene-based elastomers), making it possible to suppress thermal degradation during film formation when manufacturing the base film for the dicing sheet of the present invention. In addition, olefin-based thermoplastic elastomers have improved storage stability compared to other elastomer resins (e.g., styrene-based elastomers), making it possible to suppress fluctuations in physical properties during storage of the base film for the dicing sheet of the present invention.

[0042] Furthermore, in the present invention, if the C layer has an olefin-based thermoplastic elastomer, the manufacturing process for the dicing sheet base film of the present invention can be simplified, and processing costs can be reduced. This is because, when other elastomer resins, such as styrene-based elastomers, are used, it is necessary to blend several types of styrene-based elastomers in order to control the physical properties, which complicates the manufacturing process.

[0043] The presence of an olefin-based thermoplastic elastomer makes it possible to extrude the material used in the production of the dicing sheet base film of the present invention with fewer types of resins, eliminating the need to prepare multiple types of raw materials.

[0044] In the present invention, the olefin-based thermoplastic elastomer in the C layer may be only one type, or it may be a blend of two or more types.

[0045] Examples of olefin-based thermoplastic elastomers include propylene-based elastomers, ethylene-based elastomers, and 1-butene-based elastomers.

[0046] In the present invention, the olefin-based thermoplastic elastomer in the C layer preferably has a density of 0.830 g / cm³. ３ ~0.890g / cm ３ A more preferable concentration is 0.835 g / cm³. ３ ~0.888g / cm ３ And more preferably 0.835 g / cm³ ３ ~0.886g / cm ３ The most preferred concentration is 0.840 g / cm³. ３ ~0.885g / cm ３ The most preferred concentration is 0.845 g / cm³. ３ ~0.885g / cm ３ Therefore, by employing an olefin-based thermoplastic elastomer with a density within the above range, it becomes possible to provide a base film for dicing sheets with superior cutability.

[0047] In the present invention, the olefin-based thermoplastic elastomer in the C layer has an MFR at 230°C and 21.17 N that is preferably 5.0 g / 10 min to 25.0 g / 10 min, more preferably 5.0 g / 10 min to 23.0 g / 10 min, even more preferably 5.0 g / 10 min to 21.0 g / 10 min, particularly preferably 5.0 g / 10 min to 20.0 g / 10 min, and most preferably 5.0 g / 10 min to 19.0 g / 10 min. By employing an olefin-based thermoplastic elastomer whose MFR falls within the above range, it is possible to provide a base film for dicing sheets with superior cutability.

[0048] In the present invention, among olefin-based thermoplastic elastomers in the C layer, propylene-based elastomers are particularly preferred. By using a propylene-based elastomer as the olefin-based thermoplastic elastomer in the C layer, thermal stability is further improved, and for example, thermal degradation during film formation when manufacturing the base film for dicing sheets of the present invention can be further suppressed.

[0049] In the present invention, the content of the olefin-based thermoplastic elastomer in the C layer is preferably 30% to 100% by mass, more preferably 50% to 100% by mass, and particularly preferably 70% to 100% by mass.

[0050] In the present invention, the material of the olefin-based thermoplastic elastomer of layer C is not particularly limited, but is preferably a polyolefin resin, and preferably includes ethylene homopolymer, propylene homopolymer, ethylene copolymer, and propylene copolymer. Among these, propylene copolymer is particularly preferred.

[0051] Preferred propylene-based copolymers include propylene-α-olefin block copolymers and propylene-α-olefin random copolymers.

[0052] A propylene-α-olefin block copolymer is a preferred example.

[0053] Preferred propylene-α-olefin random copolymers include propylene-ethylene random copolymers and propylene-(1-butene) random copolymers. Among these, propylene-ethylene random copolymers and propylene-ethylene block copolymers are particularly preferred, with propylene-ethylene block copolymers being preferred due to their good lamination properties with layer B.

[0054] Furthermore, in the present invention, it is preferable that the resin hardness of layer C be 20 or more and 60 or less on the Shore D hardness scale. In particular, it is preferable that the olefin-based thermoplastic elastomer in layer C has a Shore D hardness of 20 or more and 60 or less. If the Shore D hardness is less than 20, the adhesiveness of the film after film formation may increase, which can be a factor in the deterioration of blocking properties. Also, there may be concerns about a decrease in physical properties, which can be a factor in the breakage of the dicing film during the expand process. If the Shore D hardness exceeds 60, the flexibility of the dicing film may be lost, which can be a problem in terms of expandability and breakage during the expand process.

[0055] The olefin-based thermoplastic elastomer in the C layer mentioned above, such as a propylene-based elastomer, can be obtained as a commercially available product. Examples of such commercially available products include the "Toughmer" (registered trademark) XM series and the "Toughmer" (registered trademark) PN series from Mitsui Chemicals, Inc., and the "Vistamax" (registered trademark) series from ExxonMobil (e.g., Vistamax 6202, Vistamax 3980FL, etc.).

[0056] In the present invention, the olefin-based thermoplastic elastomer in the C layer is preferably one manufactured using a metallocene catalyst. The olefin-based thermoplastic elastomer manufactured using a metallocene catalyst makes it possible to provide a base film for dicing sheets with excellent cutability, and also has even greater thermal stability compared to other elastomers (e.g., styrene-based elastomers), making it possible to further suppress thermal degradation during film formation when manufacturing the base film for dicing sheets of the present invention.

[0057] The C layer may contain any other suitable components as long as they do not impair the effects of the present invention. Examples of such other components include other polymers, tackifiers, plasticizers, degradation inhibitors, pigments, dyes, antioxidants, antistatic agents, lubricants, foaming agents, heat stabilizers, light stabilizers, inorganic particles, and organic particles. These may be present individually or in combination of two or more. In particular, the addition of organic particles is preferable because it reduces adhesion to the conveyor roll, increases the conveying speed, and improves productivity.

[0058] Specific examples of organic fine particles include polyethylene, polystyrene, and polymethyl methacrylate, but polyethylene fine particles are more preferable. The average particle size of the organic fine particles is preferably 30 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably around 10 μm. The average particle size of the organic fine particles is preferably 3 μm or more, and more preferably 5 μm or more.

[0059] The content of other components in layer C is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, particularly preferably 2% by mass or less, and most preferably 1% by mass or less.

[0060] The thickness of the C layer is preferably 5 μm to 50 μm, more preferably 5 μm to 40 μm, and even more preferably 5 μm to 30 μm. By having the thickness of the C layer within this range, it is possible to provide a base film for dicing sheets with superior dicing properties.

[0061] [Layer B] In the present invention, Layer B contains 85% by mass or more and 99% by mass or less of propylene copolymer, and also contains 1% by mass or more and 15% by mass or less of olefin-based thermoplastic elastomer. By using this propylene copolymer and olefin-based thermoplastic elastomer, it is possible to prevent cutting debris during dicing and to give Layer B appropriate flexibility.

[0062] In this invention, if the olefin-based thermoplastic elastomer content of layer B is less than 1% by mass, uneven flow occurs between layer B and layer C during film formation, and the desired appearance quality cannot be obtained. Furthermore, if the olefin-based thermoplastic elastomer content of layer B exceeds 15% by mass, the film rigidity during film formation decreases, and film formation performance is significantly reduced due to poor film transport.

[0063] In the present invention, as the propylene copolymer, propylene-ethylene random copolymer, propylene-ethylene-butene random copolymer, propylene-ethylene block copolymer, and propylene-ethylene-butene block copolymer are preferred because they generate less cutting debris, and propylene-ethylene block copolymer and propylene-ethylene-butene block copolymer are more preferred because they have stronger interfacial adhesion with the C layer. Furthermore, the propylene copolymer is preferably 1400 MPa or less in tensile modulus as defined in JIS K7161:1994 and JIS K7162:1994, and more preferably 1000 MPa or less, as this can lower the rigidity of the film.

[0064] In the present invention, it is preferable that the propylene copolymer contained in layer B is the same as the block polypropylene contained in layer A from the viewpoint of improving interlayer adhesion, but it may be different. The propylene copolymer contained in layer B may be used alone, or two or more types may be used in combination.

[0065] In the present invention, it is preferable that the olefin-based thermoplastic elastomer contained in layer B is the same as the olefin-based thermoplastic elastomer contained in layer C above from the viewpoint of improving interlayer adhesion, but they may be different. The olefin-based thermoplastic elastomer contained in layer B above may be used alone, or two or more types may be used in combination.

[0066] The thickness of layer B is preferably 40 μm to 130 μm, and more preferably 50 μm to 120 μm. By keeping the thickness of layer B within this range, it becomes possible to more effectively prevent the generation of cutting chips even when cutting into layer B with a dicing blade.

[0067] The dicing sheet base film of the present invention is formed, and then an adhesive is applied to the C layer. It is then used as a dicing sheet in the dicing and expanding processes of semiconductor wafers.

[0068] The C layer, to which the adhesive is applied, is preferably surface-treated to improve the adhesion of the adhesive. Examples of surface treatment methods include mechanical treatments such as embossing and hairline finishing, physicochemical treatments such as plasma treatment, corona treatment, and flame treatment, and chemical treatments such as primer treatment using a coupling agent. Among these, physicochemical treatments such as plasma treatment, corona treatment, and flame treatment are more preferable considering their simplicity and reduction of environmental impact during treatment.

[0069] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to these examples. The examples and comparative examples were evaluated using the evaluation method shown below. The results are shown in Table 1.

[0070] (1) Ten-point average roughness Rz The ten-point average roughness Rz was measured using a high-precision micro-shape measuring instrument (SURFCORDER ET4000A) manufactured by Kosaka Laboratory Co., Ltd., in accordance with JIS B0601-2013. Measurements were taken 11 times at 10 μm intervals in the vertical direction, with the scanning direction set to the horizontal direction, over a range of 2 mm in the transverse direction and 0.2 mm in the vertical direction of the film. Three-dimensional analysis was performed and the results evaluated. A diamond needle with a tip radius of 2.0 μm was used, with a measuring force of 100 μN and a cutoff of 0.8 mm.

[0071] (2) Resin hardness, Shore D hardness The resin hardness of the raw materials used was measured in accordance with ASTM D2240.

[0072] (3) Evaluation of burr (whiskers) shaped cutting chip generation A. A semi-automatic dicing saw (DAD-3350) manufactured by DISCO Corporation was used. Blade: P1A861 SDC240N75BR597 Blade rotation speed: 25000 rpm Cutting speed: 200 mm / sec Cutting depth: 60 μm Cutting water volume: 1.25 liters / min Cutting water temperature: 23℃.

[0073] With the above conditions set, an A4-sized film was placed in a dicing saw and three 100mm long, 5mm spaced cuts were made in the MD direction (Machine Direction: the direction of resin flow). Then, the film was rotated 90° and three 100mm long, 5mm spaced cuts were made in the TD direction (Transverse Direction: the width direction of the resin) to cut the surface layer.

[0074] B. Observation of the cutting surface A Keyence VHX-5000 optical microscope was used to observe nine points in a cross shape where the MD and TD lines intersected. Magnification: ×1000 Judgment criteria ○: 0 burrs (hairs) △: 1 to 4 burrs (hairs) ×: 5 or more burrs (hairs).

[0075] (4) Blocking evaluation Prepare a film sample with a width of 30 mm and a length of 100 mm, overlap the A layer (front) and C layer (back) in a 30 mm x 40 mm area, and apply 4.9 N (0.5 kgf) / 12 cm ２ After applying a load and aging at 23°C for 24 hours, the shear peeling force was measured using an A&D Tensilon at a tensile speed of 300 mm / min. Criteria: ○: 0.5 N / 12 cm ２ Less than ×: 0.5 N / 12 cm ２ That's all.

[0076] (5) Conveyance The film on the conveyor roll during film formation was checked and the following evaluation was performed regarding conveyance. ○: There was no adhesion to the conveyor roll, and the conveyance speed could be increased, resulting in stable production. △: Adhesion to the conveyor roll was observed, but stable production was still possible. ×: There was adhesion to the conveyor roll, resulting in resin adhering to the conveyor roll and wrinkles forming in the film, which resulted in poor stable productivity.

[0077] (6) Average particle size of organic fine particles is determined by the Coulter counter method.

[0078] <Polyethylene Microparticle Masterbatch> (A1): A polyethylene microparticle masterbatch (A1) was prepared consisting of high molecular weight polyethylene microparticles "Mipelon" PM200 manufactured by Mitsui Chemicals, Inc. with an average particle size of 10 μm, and an ethylene α-olefin copolymer ("Evolue" SP1540 manufactured by Prime Polymer, Inc., MFR 3.8 g / min (measured at 190°C, 21.17 N)) in a mass ratio of 10:90.

[0079] (A2): An acrylic microparticle masterbatch (A2) was prepared consisting of cross-linked acrylic monodisperse particles MX-1500H manufactured by Soken Chemical Co., Ltd., with an average particle size of 15 μm, and an ethylene α-olefin copolymer (Prime Polymer Co., Ltd.'s "Evolue" SP1540, MFR 3.8 g / min (measured at 190°C, 21.17 N)) in a mass ratio of 10:90.

[0080] (7) Surface resistivity ρs1, antistatic dicing sheet substrate film was stored in a room at 23°C and 65% RH for 24 hours. Under the same conditions, the surface resistivity of the A-layer surface was measured using a digital ultra-high resistance / micro-current meter R8340A with an applied voltage of 100V for 10 seconds, and the antistatic properties were evaluated according to the following criteria. Each measurement was performed five times, and the arithmetic mean of the five measurements was taken as the ρs1 (Ω / sq) of each surface of the dicing sheet substrate film. <Antistatic properties> A: ρs1 is 1.0 × 10 ７ Ω / sq or more 1.0×10 １０ Less than Ω / sq B: ρs1 is 1.0 × 10 １０ Ω / sq or more 1.0×10 １３ Ω / sq or less C: ρs1 is 1.0×10 ７ Less than Ω / sq, or 1.0 × 10⁻⁶ １３ It is greater than Ω / sq.

[0081] (8) Surface resistivity ρs² and stability of antistatic properties For samples with an antistatic evaluation result of A or B, the surface resistivity ρs² (Ω / sq) was measured using the following procedure. First, the dicing sheet substrate film was stored in a hot air oven at 80°C for 10 minutes, then stored in a room at 23°C and 65% RH for 24 hours. Under the same conditions, the surface resistivity was measured on the A-layer side surface and the B-layer side surface using a digital ultra-high resistance / micro-current meter R8340A with an applied voltage of 100V and an applied time of 10 seconds. Each measurement was performed five times, and the arithmetic mean of the five measurements was taken as the ρs² (Ω / sq) for each surface of the dicing sheet substrate film, and the stability of the antistatic properties was evaluated according to the following criteria. <Stability of antistatic properties> A: ρs² / ρs1 is 0.5 or more and 1.5 or less B: ρs² / ρs1 is less than 0.5 or greater than 1.5.

[0082] <Resin> (PE1) Product name "Evolue" SP1540, ethylene α-olefin copolymer, manufactured by Prime Polymer Co., Ltd., density 0.913 g / cm³ ３ MFR 3.8 g / min (measured at 190°C, 21.17 N).

[0083] (PE2) Product name "Harmolex" NH745N, ethylene α-olefin copolymer, manufactured by Nippon Polyethylene Co., Ltd., density 0.913 g / cm³ ３ MFR 8.0 g / min (measured at 190°C and 21.17 N).

[0084] (PE3) Product name "Novatec" HF562, high-density polyethylene, manufactured by Nippon Polyethylene Co., Ltd., density 0.963 g / cm³ ３ MFR 7.5 g / min (measured at 190°C, 21.17 N).

[0085] (PE4) Product name "Suntech" L6810, low-density polyethylene, manufactured by Asahi Kasei Corporation, density 0.918 g / cm³ ３ MFR 10.5 g / min (measured at 190°C, 21.17 N).

[0086] (PP1) Product name "Vistamax" 3980FL, propylene elastomer, manufactured by ExxonMobil, density 0.879 g / cm³ ３ MFR 8.0 g / min (measured at 230°C and 21.17 N).

[0087] (PP2) Product name "Toughmer" XM7070, propylene-based elastomer, manufactured by Mitsui Chemicals, density 0.870 g / cm³ ３ MFR 7.0 g / min (measured at 230°C and 21.17 N).

[0088] (PP3) Product name "Topilene" J640F, propylene-α-olefin block copolymer, manufactured by HYOSUNG, density 0.900 g / cm³ ３ The MFR is 9.0 g / min (measured at 230°C and 21.17 N), and the tensile modulus of elasticity, as defined in JIS K7161 (1994), is 800 MPa.

[0089] (PP4) Propylene-α-olefin block copolymer, density 0.900 g / cm³ ３The MFR is 3.3 g / min (measured at 230°C and 21.17 N), and the tensile modulus of elasticity, as defined in JIS K7161 (1994), is 550 MPa.

[0090] (PP5) Propylene-α-olefin block copolymer, density 0.900 g / cm³ ３ The MFR is 2.0 g / min (measured at 230°C and 21.17 N), and the tensile modulus of elasticity, as defined in JIS K7161 (1994), is 650 MPa.

[0091] (PP6) Product name "Novatec PP" FW4BT, propylene-α-olefin random copolymer, manufactured by Nippon Polypropylene Co., Ltd., density 0.900 g / cm³ ３ The MFR is 6.5 g / min (measured at 230°C and 21.17 N), and the tensile modulus of elasticity, as defined in JIS K7161 (1994), is 900 MPa.

[0092] (PP7) Product name "Novatec PP" FL4, homopolypropylene, manufactured by Nippon Polypropylene Co., Ltd., density 0.900 g / cm³ ３ The MFR is 5.0 g / min (measured at 230°C and 21.17 N), and the tensile modulus of elasticity, as defined in JIS K7161 (1994), is 1850 MPa.

[0093] (AS) Sanyo Chemical Industries' antistatic agent "Perectron" (registered trademark) PVL (polyether-polyolefin block copolymer).

[0094] (Example 1) The constituent resins for each layer were prepared as follows: Layer A: 90% by mass of (PE1) and 10% by mass of (A1) were used. Layer B: 99% by mass of (PP4) and 1% by mass of (PP1) were used. Layer C: 100% by mass of (PP1) was used.

[0095] Next, the constituent resins for each layer were fed into the extruders of a T-die composite film-making machine, which has three extruders. The discharge rate of each extruder was adjusted so that layer A was 14 μm thick, layer B was 112 μm thick, and layer C was 14 μm thick. The layers were then stacked in this order and extruded from the composite T-die at an extrusion temperature of 210°C to form a film with a total thickness of 140 μm.

[0096] Subsequently, the obtained laminated films were evaluated using the method described above, and the results are shown in Table 1.

[0097] (Example 2) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A was made of 90% by mass of (PE2) and 10% by mass of (A2), layer B was made of 95% by mass of (PP4) and 5% by mass of (PP1), and layer C was made of 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0098] (Example 3) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3) and layer B used 85% by mass of (PP4) and 15% by mass of (PP1). The results are shown in Table 1.

[0099] (Example 4) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 95% by mass of (PP4) and 5% by mass of (PP2), and layer C used 100% by mass of (PP2). The results are shown in Table 1.

[0100] (Example 5) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 80% by mass of (PP3) and 20% by mass of (A1), layer B used 95% by mass of (PP5) and 5% by mass of (PP1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0101] (Example 6) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 95% by mass of (PP6) and 5% by mass of (PP1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0102] (Example 7) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), and layer B used 90% by mass of (PP6), 5% by mass of (PP1), and 5% by mass of (PP3). The results are shown in Table 1.

[0103] (Example 8) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 90% by mass of (PP3) and 10% by mass of (AS), layer B used 95% by mass of (PP5) and 5% by mass of (PP1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0104] (Example 9) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 75% by mass of (PP3) and 25% by mass of (AS), layer B used 95% by mass of (PP5) and 5% by mass of (PP1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0105] (Example 10) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 60% by mass of (PP3) and 40% by mass of (AS), layer B used 95% by mass of (PP5) and 5% by mass of (PP1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0106] (Comparative Example 1) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PE1) and layer B used 90% by mass of (PP3) and 10% by mass of (PP1). The results are shown in Table 1.

[0107] (Comparative Example 2) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3) and layer B used 95% by mass of (PP7) and 5% by mass of (PP1). The results are shown in Table 1.

[0108] (Comparative Example 3) A laminated film was formed in the same manner as in Example 1, except that layer A used 100% by mass of (PP3) and layer B used 100% by mass of (PP4). Flow unevenness occurred between layers B and C, resulting in poor film formation stability and failure to obtain the desired appearance quality.

[0109] (Comparative Example 4) The process for forming a laminated film was started in the same manner as in Example 1, except that layer A used 100% by mass of (PP3) and layer B used 80% by mass of (PP4) and 20% by mass of (PP1). However, due to a decrease in film rigidity during film formation, film formation was not possible due to poor film transport.

[0110] (Comparative Example 5) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 95% by mass of (PP4) and 5% by mass of (PP1), and layer C used 100% by mass of (PE1). The results are shown in Table 1.

[0111] (Comparative Example 6) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 95% by mass of (PP4) and 5% by mass of (PP1), and layer C used 100% by mass of (PE4). The results are shown in Table 1.

[0112] (Comparative Example 7) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 95% by mass of (PP4) and 5% by mass of (PP1), and layer C used 100% by mass of (PE3). The results are shown in Table 1.

[0113] (Comparative Example 8) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 80% by mass of (PP4), 5% by mass of (PP1), and 15% by mass of (PE1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0114] (Comparative Example 9) A laminated film was formed and evaluated in the same manner as in Example 1, except that layer A used 100% by mass of (PP3), layer B used 85% by mass of (PP4) and 15% by mass of (PE1), and layer C used 97% by mass of (PP1) and 3% by mass of (A1). The results are shown in Table 1.

[0115]

[0116]

[0117] The results in Table 1 show that the embodiment suppresses the generation of cutting chips during dicing and is less prone to blocking when wound into a roll.

[0118] On the other hand, in Comparative Example 1, blocking occurred due to the low surface roughness of layer A. In Comparative Example 2, cutting chips were easily generated during dicing due to layer B, and in Comparative Examples 5, 6, 7, 8, and 9, due to layer C. In Comparative Example 3, flow unevenness occurred between layers B and C, and the desired appearance quality could not be obtained. In Comparative Example 4, film formation was not possible due to poor film transport caused by reduced film rigidity during film formation.

[0119] Furthermore, comparing Examples 8, 9, and 10 with other examples, the application of an antistatic agent to layer A reduced the surface resistivity, resulting in good antistatic properties (ρs1) and stability of antistatic properties (ρs2 / ρs1). At 23°C and 65% RH, the surface resistivity ρs1 of the film was 1.0 × 10⁻¹⁴ for Example 8. １０ Ω / sq or more 1.0×10 １３ Examples 9 and 10 have values ​​of Ω / sq or less, and 1.0 × 10 ７ Ω / sq or more 1.0×10 １０ The value was less than Ω / sq, which was suitable for achieving both antistatic properties and other film properties and film quality. On the other hand, the ρs1 of Examples 1-7 and Comparative Examples 1-9 was 1.0 × 10⁻⁶. 13 (Ω / sq) ≤ ρs1.

Claims

1. A laminated film in which at least layers A, B, and C are arranged in this order, wherein layer A has a ten-point average roughness Rz of 1.5 μm or more and 15.0 μm or less, layer B has a propylene copolymer content of 85% by mass or more and 99% by mass or less and contains 1% by mass or more and 15% by mass or less of olefin-based thermoplastic elastomer, and layer C has an olefin-based thermoplastic elastomer, wherein this is a base film for a dicing sheet.

2. The substrate film for dicing sheets according to claim 1, wherein the olefin-based thermoplastic elastomer is a propylene-based elastomer.

3. The base film for dicing sheets according to claim 1, wherein the resin hardness of the C layer is 20 or more and 60 or less on the Shore D hardness scale.

4. The substrate film for dicing sheets according to claim 1, wherein the A layer contains organic fine particles with an average particle diameter of 3 μm or more and 30 μm or less.

5. The base film for dicing sheets according to claim 4, wherein the organic fine particles are polyethylene fine particles.

6. The substrate film for a dicing sheet according to claim 1, wherein the C layer is subjected to flame treatment, plasma treatment, or corona treatment.

7. The dicing sheet base film according to claim 1, wherein at least one side of the dicing sheet base film satisfies formula (1) of the surface resistivity ρs1 (Ω / sq) at 23°C and 65% RH. 1.0 × 10 ７ Ω / sq≦ρs1≦1.0×10 １３ Ω / sq...Formula (1) 8. The dicing sheet base film according to claim 1, wherein the surface resistivity ρs1 (Ω / sq) at 23°C and 65% RH on at least one side of the dicing sheet base film satisfies formula (2) when the surface resistivity ρs2 (Ω / sq) at 23°C and 65% RH after heating the dicing sheet base film at 80°C for 10 minutes is 0.5 ≤ (ρs2 / ρs1) ≤ 1.5 ... formula (2)

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