Base film for semiconductor manufacturing tape

Abstract

This base film (1) for a semiconductor manufacturing tape has a functional layer (2) and a surface layer (3) that is provided on at least one side of the functional layer (2). The functional layer (2) contains a homopolymer of 1-butene, a copolymer of a pentene, and an olefin-based elastomer. The content of the olefin-based elastomer relative to the entirety of the functional layer (2) is 10% by mass to 40% by mass inclusive. At least one of the functional layer (2) and the surface layer (3) contains a plant-derived olefin-based resin. The biomass degree in the entirety of the base film (1) for a semiconductor manufacturing tape is not less than 4% by mass but less than 49% by mass.

Description

Substrate film for semiconductor manufacturing tape

[0001] The present invention relates to a substrate film for a tape for semiconductor manufacturing (hereinafter, sometimes simply referred to as "substrate film").

[0002] A widely used method for manufacturing semiconductor devices such as IC chips is to divide a wafer circuit, in which a circuit is formed on a substantially circular semiconductor wafer, by dicing it on a semiconductor manufacturing tape (dicing tape) for wafers to obtain individual semiconductor devices. After dicing, for example, the dicing tape is stretched to form gaps between the semiconductor devices (i.e., expanded), and then each semiconductor device is picked up by a robot or the like.

[0003] In addition, a dicing die attach film (DDAF) in which an adhesive layer is laminated on the adhesive layer of the above-mentioned dicing tape is used as a semiconductor manufacturing tape for wafers. After the wafer circuit is divided by dicing on the dicing die attach film, the dicing die attach film is stretched to form gaps between the semiconductor devices, and then the adhesive layer is photo-cured, and the semiconductor devices are peeled off from the adhesive layer and picked up with the adhesive layer still adhered.

[0004] In recent years, there has been a growing need to reduce the amount of carbon dioxide emitted in order to reduce environmental impact and combat global warming, and substrate films for semiconductor manufacturing tapes containing plant-derived (biomass-derived) materials have also been proposed.

[0005] For example, a substrate film has been proposed that contains a chlorine-containing resin such as a vinyl chloride resin, a resin containing succinic acid and 1,4-butanediol, which are plant-derived components, as copolymer components, and an epoxy group-containing resin (see, for example, Patent Document 1).

[0006] Furthermore, in order to reduce the environmental impact, a substrate film using a polyolefin resin instead of the vinyl chloride resin has been proposed. For example, a random copolymer of propylene with ethylene and / or an α-olefin having 4 to 8 carbon atoms, in which the content of ethylene and / or an α-olefin having 4 to 8 carbon atoms is 6% by weight or more, and the density measured in accordance with ASTM D1505 is 885 kg / m ３ A substrate film has been proposed that is constructed from a laminate of an intermediate layer containing the following propylene-based random copolymer (β) as a main component, and surface layers laminated on both sides of the intermediate layer and containing a propylene-based random copolymer (α) as a main component, the propylene-based random copolymer having a lower content of ethylene and / or an α-olefin having 4 to 8 carbon atoms and a higher density than the propylene-based random copolymer (β) (see, for example, Patent Document 2).

[0007] JP 2011-61189 A JP 2018-65327 A

[0008] However, although the substrate film described in Patent Document 1 can reduce the environmental impact, it uses a chlorine-containing resin such as vinyl chloride resin, which causes chloride ions to migrate to the semiconductor wafer and contaminate the semiconductor element, which is a problem.

[0009] Furthermore, the substrate film described in Patent Document 2 has stress relaxation properties that allow it to replace vinyl chloride resin, but because it uses a semi-crystalline resin rather than an amorphous resin, necking occurs when the substrate film is stretched to form gaps between semiconductor devices, resulting in insufficient uniform stretchability of the substrate film. Furthermore, because the substrate film has poor rigidity, there are problems with the substrate unwinding and tape formation, including adhesive application, being unstable in the substrate film manufacturing process.

[0010] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a substrate film for semiconductor manufacturing tape that can reduce environmental impact and has excellent uniform elongation, rigidity, and stress relaxation properties.

[0011] In order to achieve the above object, the substrate film for a semiconductor manufacturing tape of the present invention is a substrate film for a semiconductor manufacturing tape having a functional layer and a surface layer provided on at least one side of the functional layer, wherein the functional layer contains a 1-butene homopolymer, a pentene copolymer, and an olefin-based elastomer, the content of the olefin-based elastomer relative to the entire functional layer is 10% by mass or more and 40% by mass or less, at least one of the functional layer and the surface layer contains a plant-derived olefin-based resin, and the biomass content of the entire substrate film for a semiconductor manufacturing tape is 4% by mass or more and less than 49% by mass.

[0012] According to the present invention, it is possible to provide a substrate film for a tape for manufacturing semiconductor devices that can reduce the environmental load and has excellent uniform elongation, rigidity, and stress relaxation properties.

[0013] 1 is a cross-sectional view showing a substrate film for a semiconductor manufacturing tape according to an embodiment of the present invention, and FIG. 2 is an SS curve (stress-strain curve) of the substrate film of Example 1.

[0014] The substrate film for a semiconductor manufacturing tape of the present invention will be specifically described below. Note that the present invention is not limited to the following embodiments, and appropriate modifications can be made within the scope of the present invention.

[0015] The substrate film of the present invention is a substrate film constituted by a laminate of a functional layer (intermediate layer) and a surface layer provided on at least one side of the functional layer.

[0016] An example of a substrate film having this multilayer structure is a substrate film 1 having a three-layer structure, as shown in Figure 1, which is composed of a laminate of a functional layer 2 and surface layers 3 laminated on both sides of the functional layer 2, and is laminated in the order of surface layer / functional layer / surface layer.

[0017] The functional layer may contain a 1-butene homopolymer, a pentene copolymer, and an olefin-based elastomer.

[0018] <1-butene homopolymer> In the present invention, a homopolymer obtained by polymerizing 1-butene alone is used as the polybutene. This 1-butene homopolymer has a high molecular weight and bulky side chains. The strong intermolecular forces caused by these bulky side chains enable the homopolymer to improve the uniform stretchability of the substrate film, similar to that of an amorphous polymer, despite being a crystalline polymer.

[0019] The 1-butene homopolymer used in the present invention may have a weight average molecular weight (Mw) of about 500,000 to 1,500,000.

[0020] The "weight average molecular weight" refers to the value calculated in accordance with JIS K 7252-1:2016.

[0021] Furthermore, the 1-butene homopolymer used in the present invention has a high molecular weight, and therefore has low surface tackiness, and is also more rigid than amorphous polyolefins. Therefore, in the production process of the substrate film, it is possible to provide a substrate film having high rigidity that can be formed into a tape, including unwinding the substrate and coating with an adhesive.

[0022] As described above, by using a 1-butene homopolymer as the resin forming the substrate film, the uniform extensibility and rigidity of the substrate film can be improved.

[0023] In addition, from the viewpoint of improving uniform elongation and rigidity, the content of 1-butene homopolymer in the entire functional layer 2 is preferably 30% by mass or more and 85% by mass or less, and more preferably 30% by mass or more and 60% by mass or less, out of 100% by mass of the functional layer.

[0024] <Pentene Copolymer> In the base film 1 of the present invention, the functional layer 2 contains a pentene copolymer as polypentene from the viewpoint of improving the stress relaxation property that enables the dimensions of the semiconductor manufacturing tape to be maintained after expanding. The use of such a pentene copolymer improves the stress relaxation property of the base film 1, making it possible to hold the semiconductor manufacturing tape with a grip ring and maintain the spacing between each semiconductor device (semiconductor chip).

[0025] Although there are no particular limitations on this pentene copolymer, a copolymer of 4-methyl-1-pentene and an α-olefin is preferred, which has a glass transition temperature near room temperature, is excellent in stress relaxation properties, and has good flexibility due to the α-olefin copolymer component. Examples include "Absortomer (registered trademark) EP-1013" and "Absortomer (registered trademark) EP-1001," both trade names of Mitsui Chemicals, Inc., which are copolymers of 4-methyl-1-pentene and polypropylene.

[0026] When a copolymer of 4-methyl-1-pentene and polypropylene is used, from the viewpoint of improving flexibility and stress relaxation properties, the content of polypropylene relative to the entire copolymer of 4-methyl-1-pentene and polypropylene is preferably 10 mol % or more and 30 mol % or less, based on 100 mol % of the copolymer of 4-methyl-1-pentene and polypropylene.

[0027] From the viewpoint of improving stress relaxation, the content of the pentene copolymer in the entire functional layer 2 is preferably 10% by mass or more and 40% by mass or less, based on 100% by mass of the functional layer.

[0028] <Olefin-Based Elastomer> In the base film 1 of the present invention, the functional layer 2 contains an olefin-based elastomer. The olefin-based elastomer is composed of an olefin-based material that conforms to the definition of the term elastomer in JIS K 6200. More specifically, a material composed of a copolymer of amorphous or low-crystalline α-olefins corresponds to the olefin-based elastomer, while an ethylene-based elastomer is one that is primarily composed of polyethylene, and a propylene-based elastomer is one that is primarily composed of polypropylene. For example, an ethylene-based elastomer is available under the trade name "Tafmer (registered trademark)" manufactured by Mitsui Chemicals, Inc., and an propylene-based elastomer is available under the trade name "Vistamax (registered trademark)" manufactured by ExxonMobil Corporation.

[0029] When a propylene-based elastomer is used, the content of polyethylene in the entire propylene-based elastomer is preferably 9% or more and 30% or less, based on 100% of the propylene-based elastomer, from the viewpoint of improving flexibility.

[0030] By using such an olefin-based elastomer, the crystallinity is reduced and the occurrence of a yield point can be suppressed, thereby improving the uniform extensibility of the substrate film.

[0031] Furthermore, from the viewpoint of improving uniform elongation, the content of the olefin-based elastomer in the entire functional layer 2 is 10% by mass or more and 40% by mass or less, with respect to 100% by mass of the functional layer 2. If the content of the olefin-based elastomer exceeds 40% by mass, the olefin-based elastomer component with low crystallinity will be excessive, which may reduce rigidity and make it difficult to unwind the substrate and form it into a tape, including applying an adhesive.

[0032] The content of the olefin-based elastomer in the entire functional layer 2 is preferably 20% by mass or more and 30% by mass or less, based on 100% by mass of the functional layer.

[0033] From the viewpoint of further improving uniform elongation, the density of the olefin-based elastomer is 0.850 to 0.900 g / cm ３ is preferably 0.860 to 0.890 g / cm ３ It is more preferable that:

[0034] Next, the surface layer 3 in the base film 1 of the present invention will be described. Examples of the surface layer 3 include those containing the above-mentioned 1-butene homopolymer, or polyolefin resins such as polyethylene and polypropylene.

[0035] Despite its high molecular weight, a 1-butene homopolymer can be molded using a general-purpose extruder, and since the high molecular weight component results in low surface adhesion of the film, when used in a surface layer, it can suppress adhesion to transport rolls when transporting the base film, as well as suppress blocking when winding the base film and draw resonance when molding the base film, thereby improving the processing stability of the base film.

[0036] Examples of polypropylene include polypropylene homopolymers and copolymers. Among these, polypropylene homopolymers are homopolypropylenes obtained by polymerizing propylene alone. These polypropylene homopolymers have high stereoregularity and a high degree of crystallinity that contributes to the melting point, resulting in excellent heat resistance. Furthermore, although they have high rigidity due to their high degree of crystallinity, blending them with linear low-density polyethylene can provide flexibility that contributes to the expandability of the substrate film.

[0037] <Low-density polyethylene> The surface layer 3 is made of a polyolefin-based resin having a low density of 0.860 g / cm ３ 0.93g / cm or more ３ Preferably, the polyethylene contains low density polyethylene (LDPE) having a density of 0.860 g / cm or less. ３ 0.93g / cm or more ３ The low-density polyethylene described below has low surface adhesion, and therefore, when used in the surface layer, it can suppress adhesion to the transport roll when the base film is transported and can also suppress blocking when the base film is wound up, thereby improving the processing stability of the base film.

[0038] Furthermore, among low-density polyethylenes, linear low-density polyethylene (LLDPE) has side-chain branches in the linear chain structure of high-density polyethylene, and therefore does not have an excessively high degree of crystallinity compared to high-density polyethylene, and is therefore excellent in flexibility.

[0039] From the viewpoint of strength, linear low-density polyethylene produced using a metallocene catalyst or a Ziegler catalyst may also be used.

[0040] The linear low-density polyethylene preferably has a melt mass-flow rate (MFR) of 0.5 to 7.5 g / 10 min, more preferably 1.0 to 6.0 g / 10 min, and even more preferably 2.0 to 5.0 g / 10 min. When the melt mass-flow rate (MFR) is 0.5 g / 10 min or higher, the molecular weight is not too large, allowing for improved flexibility and processability, while when the MFR is 7.5 g / 10 min or lower, the molecular weight is not too small, allowing for improved processing stability.

[0041] The melt mass flow rate can be obtained by measuring in accordance with the provisions of JIS K7210:1999.

[0042] From the viewpoint of improving uniform extensibility and rigidity, the content of linear low-density polyethylene in the entire surface layer 3 is preferably 12% by mass or more and 70% by mass or less, based on 100% by mass of the surface layer.

[0043] From the above, the density is 0.93 g / cm ３ By using a low density polyethylene having a density of 1000 or less, the flexibility and isotropy of the base film can be improved.

[0044] Furthermore, from the viewpoint of improving uniform elongation and rigidity, it is preferable that the content of 1-butene homopolymer in the surface layer 3 (i.e., each of the surface layers 3 laminated on both sides of the functional layer 2) is more than 0 mass% and 30 mass% or less, based on 100 mass% of the surface layer.

[0045] <Plant-derived olefin-based resin> In the base film 1 of the present invention, from the viewpoint of reducing the environmental load, at least one of the functional layer 2 and the surface layer 3 contains a plant-derived (biomass-derived) olefin-based resin.

[0046] Examples of plant-derived olefin resins that can be used include plant-derived low-density polyethylene (LDPE), plant-derived linear low-density polyethylene (LLDPE), and plant-derived high-density polyethylene (HDPE).

[0047] Plant-derived low-density polyethylene is a biomass polyethylene that is a polymer of monomers containing ethylene derived from biomass, and an example of such a low-density polyethylene is sugarcane-derived low-density polyethylene.

[0048] In addition, in the base film of the present invention, low-density polyethylene having a biomass content of 95% or more is used.

[0049] The "biomass content" here specifically refers to the amount of radiocarbon ( １４ This refers to a value measured based on the principle of radiocarbon dating by determining the concentration of carbon dioxide (C).

[0050] Furthermore, in the base film of the present invention, the biomass degree of the entire base film is 4% by mass or more and less than 49% by mass, based on 100% by mass of the base film. If the biomass degree is less than 4% by mass, the reduction in environmental impact will be insufficient, and if the biomass degree is 49% by mass or more, the amount of biomass-derived olefin resin with a low crystallinity will be excessive, resulting in a decrease in rigidity and making it difficult to unwind the base and to form it into a tape, including applying a pressure-sensitive adhesive.

[0051] That is, if the biomass content of the entire base film is within the above range, it is possible to sufficiently reduce the environmental load and to sufficiently improve the rigidity of the base film.

[0052] The biomass content of the entire base film is preferably 7.5% by mass or more and 45% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0053] Furthermore, in the base film of the present invention, when the functional layer 2 contains a plant-derived olefin-based resin, the content of the plant-derived olefin-based resin in the entire functional layer 2 is not particularly limited as long as the biomass degree in the entire base film is the above-mentioned 4 mass% or more and less than 49 mass%, but can be, for example, 5 mass% or more and 45 mass% or less out of 100 mass% of the functional layer.

[0054] Similarly, in the base film of the present invention, when the surface layer 3 contains a plant-derived olefin-based resin, the content of the plant-derived olefin-based resin in the entire surface layer 3 is not particularly limited as long as the biomass degree in the entire base film is the above-mentioned 4% by mass or more and less than 49% by mass, but can be, for example, 10% by mass or more and 90% by mass or less, relative to 100% by mass of the surface layer.

[0055] From the viewpoints of improving processing stability and reducing environmental load, the content of low-density polyethylene in the entire surface layer 3 (i.e., the total content of the above-mentioned low-density polyethylene and the plant-derived low-density polyethylene) is preferably 70% by mass or more and 100% by mass or less, based on 100% by mass of the surface layer.

[0056] In addition, when using plant-derived low-density polyethylene, the density is 0.930 g / cm ３ Preferably, the plant-derived low-density polyethylene has a density of 0.930 g / cm or less. ３ In the following cases, the degree of crystallinity is not too high and flexibility is excellent.

[0057] From the viewpoint of improving processing stability, the density of the plant-derived low-density polyethylene is 0.860 g / cm ３ It is preferable that the density is 0.870 g / cm or more. ３ More preferably, it is equal to or greater than this.

[0058] The melt mass flow rate (MFR) of the plant-derived low-density polyethylene is preferably 0.5 to 7.5 g / 10 min, more preferably 1.0 to 6.0 g / 10 min, and even more preferably 2.0 to 5.0 g / 10 min. When the melt mass flow rate (MFR) is 0.5 to 7.5 g / 10 min, processing stability can be improved.

[0059] The melt mass flow rate can be obtained by measuring in accordance with the standard of ASTM D1238.

[0060] <Substrate Film> In the substrate film 1 of the present invention, the stress (at 20% elongation) in the mechanical axis (longitudinal) direction (hereinafter referred to as "MD") of the substrate film and the direction perpendicular thereto (hereinafter referred to as "TD") is preferably 7.0 MPa to 20 MPa, more preferably 7.5 MPa to 15 MPa, and even more preferably 8 MPa to 13 MPa. If the stress is greater than 20 MPa, the rigidity will be too high, which may reduce the pickup ability of semiconductor devices and result in damage to the semiconductor devices. If the stress is less than 7.0 MPa, the rigidity will be low, which may make it difficult to unwind the substrate during the substrate film production process and to form the substrate into a tape, including coating with an adhesive.

[0061] That is, when the stress in MD and TD (at 20% elongation) is 7.0 MPa or more and 20 MPa or less, a substrate film having excellent rigidity can be provided in the substrate film manufacturing process, which allows the substrate to be unwound and formed into a tape, including the application of an adhesive.

[0062] Furthermore, in the case of a conventional substrate film containing polyolefin, necking does not occur when the substrate film is stretched by 20%, and uniform expansion is possible, but necking begins to occur when the substrate film is stretched by 40%, making uniform expansion difficult.

[0063] Therefore, in the base film 1 of the present invention, from the viewpoint of improving the uniform extensibility of the base film, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) in the MD and TD (i.e., the elongation of the base film) is preferably from 0.95 to 2. If the elongation of the base film is greater than 2, the excessive increase in stress may make it difficult to hold the expanding ring, and if the elongation of the base film is less than 0.95, necking may occur, making uniform expansion difficult.

[0064] That is, when the elongation percentage of the base film is 0.95 or more and 2 or less, necking does not occur and uniform expansion becomes possible.

[0065] It is more preferable that the elongation percentage of the base film is 1 or more and 1.80 or less, and from the viewpoint of preventing necking and ensuring uniform expansion, it is even more preferable that the elongation percentage of the base film is 1.05 or more and 1.70 or less.

[0066] In the base film 1 of the present invention, from the viewpoint of further improving the uniform extensibility of the base film, the ratio of stress (at 5% elongation) to stress (at 40% elongation) is preferably 1.05 or less in both MD and TD. If the ratio of stress (at 5% elongation) to stress (at 40% elongation) is 1.05 or less, the occurrence of the later-described yield point (the yield point during elongation from 0% to 100% at a tensile speed of 300 mm / min) can be suppressed, thereby suppressing the occurrence of necking and enabling uniform expansion.

[0067] It is more preferable that the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) is 0.40 or more and 1.05 or less, and from the viewpoint of preventing the occurrence of necking and ensuring uniform expansion, it is even more preferable that the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) is 0.60 or more and less than 0.90.

[0068] Furthermore, the base film 1 of the present invention preferably has a stress relaxation rate of 25% or more, more preferably 30% or more, and even more preferably 35% or more. If the stress relaxation rate is less than 25%, the stress absorption performance is poor, and it may become difficult to maintain the dimensions of the tape for semiconductor manufacturing.

[0069] That is, when the stress relaxation rate is 25% or more, the dimensions of the tape for semiconductor manufacturing can be maintained, and a substrate film for a tape for semiconductor manufacturing having excellent stress relaxation properties can be provided.

[0070] The "stress relaxation rate" referred to here can be determined by the method described in the examples below.

[0071] Furthermore, from the viewpoint of suppressing the occurrence of slack due to the isotropy of the base film during expansion, the ratio of the stress in MD (at 20% elongation) to the stress in TD (at 20% elongation) (i.e., the stress ratio of the base film at 20% elongation) is preferably 0.80 or more and 1.30 or less, more preferably 0.85 or more and 1.25 or less, and even more preferably 0.90 or more and 1.20 or less.

[0072] The thickness of the substrate film 1 of the present invention is preferably 50 to 300 μm, more preferably 80 to 150 μm. If the thickness of the substrate film is 50 μm or more, the handleability is improved, and if the thickness is 300 μm or less, the flexibility (expandability) can be improved. In the case of a substrate film for wafers, the thickness of the substrate film is preferably 50 to 150 μm, more preferably 70 to 110 μm.

[0073] For example, in the case of a substrate film having a three-layer structure in which a surface layer / a functional layer / a surface layer are laminated in this order, the thickness of the surface layer is not particularly limited, but is preferably 2 to 60 μm, more preferably 4 to 40 μm, and the thickness of the functional layer is not particularly limited, but is preferably 40 to 120 μm, more preferably 50 to 80 μm.

[0074] Furthermore, for example, in the case of a substrate film having a three-layer structure in which a surface layer / a functional layer / a surface layer are laminated in this order, the ratio of the functional layer to the entire substrate film is preferably 40 to 95%, more preferably 50 to 90%, from the viewpoints of processability and low cost.

[0075] <Manufacturing Method> For example, when manufacturing a substrate film 1 having a three-layer structure in which a surface layer / a functional layer / a surface layer are laminated in this order as shown in FIG. 1, first, a resin material for forming the surface layer and a resin material for forming the functional layer are prepared.

[0076] Next, a three-kind, three-layer co-extruder equipped with a T-die is used to simultaneously extrude and mold the resin material for forming the surface layer and the resin material for forming the functional layer at a predetermined temperature, thereby producing the substrate film 1 of the present invention having a multilayer structure constituted by a laminate of the functional layer 2 and the surface layers 3 laminated on both sides of the functional layer 2. The substrate film of the present invention may also be produced by a known calendar method or inflation method.

[0077] <Other Embodiments> The substrate film 1 of the present invention may contain various additives. Examples of the additives include known additives commonly used in semiconductor manufacturing tapes, such as cross-linking aids, antistatic agents, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, colorants, nucleating agents, and processing aids. These additives may be used alone or in combination of two or more.

[0078] Furthermore, examples of the crosslinking aid include triallyl isocyanurate. When the base film contains a crosslinking aid, the content of the crosslinking aid in the base film is preferably 0.05 to 5 parts by mass, and more preferably 1 to 3 parts by mass, relative to 100 parts by mass of the resin forming the base film.

[0079] Furthermore, the above description has been given taking as an example a substrate film having a three-layer structure in which surface layer / functional layer / surface layer are laminated in this order. However, the substrate film having a multilayer structure of the present invention is not limited to a three-layer structure as long as it has the above-mentioned functional layer, and may be, for example, a substrate film having a five-layer structure in which surface layer / functional layer / functional layer / functional layer / surface layer are laminated in this order.

[0080] Furthermore, in the above-described embodiment, the substrate film 1 having a three-layer structure in which a surface layer / a functional layer / a surface layer are laminated in this order has been described as an example. However, the substrate film of the present invention may also be a substrate film having a single-layer structure consisting of only the functional layer 2 described above.

[0081] In this case, first, a resin material for forming the functional layer is prepared, and then a three-kind, three-layer co-extruder equipped with a T-die is used to extrude and mold the resin material for forming the functional layer at a predetermined temperature, thereby producing a substrate film having a single-layer structure consisting of only the functional layer 2. As in the above-described embodiment, the substrate film may also be produced by a known calendar method or inflation method.

[0082] The present invention will be described below based on examples. However, the present invention is not limited to these examples, and these examples can be modified or changed based on the spirit of the present invention, and such modifications are not excluded from the scope of the present invention.

[0083] The materials used to prepare the substrate film are as follows: (1) LLDPE: linear low-density polyethylene, melting point: 121°C, density: 0.922 g / cm ３ , MFR: 1.6 g / 10 min (2) LDPE: plant-derived low-density polyethylene, biomass content: 95%, density: 0.918 g / cm ３ , MFR (190 ° C): 8.3 g / 10 min (3) 1-Bu: 1-butene homopolymer, melting point: 128 ° C, density: 0.920 g / cm ３ , MFR: 0.5 g / 10 min (4) PP elastomer 1: propylene-based elastomer, density: 0.862 g / cm ３ , MFR: 3.0 g / 10 min (230 ° C), polyethylene content: 16% (manufactured by ExxonMobil Corporation, trade name: Vistamax (registered trademark) 6102FL) (5) PP elastomer 2: propylene-based elastomer, density: 0.889 g / cm ３ , MFR: 8.0 g / 10 min (230 ° C), polyethylene content: 4% (manufactured by ExxonMobil Corporation, trade name: Vistamax (registered trademark) 3588FL) (6) Pentene copolymer: copolymer of 4-methyl-1-pentene and polypropylene, melting point: 130 ° C, density: 0.838 g / cm ３ , MFR: 10.0 g / 10 min, 4-methyl-1-pentene content: 85 mol%, polypropylene content: 15 mol%

[0084] Example 1 <Preparation of Substrate Film> First, the materials shown in Table 1 were blended to prepare a resin material for forming a surface layer and a resin material for forming a functional layer, each having the composition (parts by mass) shown in Table 1. Next, these resin materials were simultaneously extruded through a T-die using a three-kind, three-layer co-extruder at a die temperature of 180 to 230°C and a chill roll temperature of 30°C, to obtain a substrate film having the thickness shown in Table 1 and a three-layer structure in which the surface layer / functional layer / surface layer were laminated in this order.

[0085] Table 1 also shows the biomass content [mass %] of the entire substrate film.

[0086] In this example, each surface layer contains 14 parts by mass of plant-derived low-density polyethylene (biomass content: 95%) per 100 parts by mass. The total thickness of the two surface layers is 40 μm relative to the overall thickness of the base film (20 μm + 70 μm + 20 μm = 110 μm). Therefore, the biomass content of the entire base film is 95 × (14 / 100) × (40 / 110) = 4.8% by mass.

[0087] <Evaluation of Presence or Absence of Yield Point> Using the produced substrate film, a measurement sample was obtained in accordance with JIS K7161-2: 2014. Next, the obtained measurement sample was set in a tensile tester (manufactured by Shimadzu Corporation, product name: AG-5000A) so that the distance between the grippers was 40 mm, and a tensile test was performed in accordance with JIS K7161-2: 2014 at a temperature of 23°C and a relative humidity of 40% at a tension rate of 300 mm / min.

[0088] In the MD and TD S-S curves (stress-strain curves), those in which no yield point was observed during the elongation rate from 0% to 100% (no necking occurred and uniform expansion was reliably possible) were marked with a ◎, those in which almost no yield point was observed during the elongation rate from 0% to 100% (necking was suppressed and almost uniform expansion was possible) were marked with a ○, and those in which a yield point was observed (necking occurred and uniform expansion was not possible) were marked with an ×. The results are shown in Table 1.

[0089] <Measurement of stress in MD and TD> Using the produced substrate film, a measurement sample was obtained in accordance with JIS K7161-2: 2014. Next, the obtained measurement sample was set in a tensile tester (manufactured by Shimadzu Corporation, product name: AG-5000A) so that the distance between the grippers was 40 mm, and a tensile test was performed in accordance with JIS K7161-2: 2014 at a temperature of 23°C and a relative humidity of 40% at a tension speed of 300 mm / min.

[0090] The stress at 20% elongation (20% stress) in the MD and TD of the substrate film was measured, and the ratio of the stress in the MD (at 20% elongation) to the stress in the TD (at 20% elongation) (i.e., the stress ratio of the substrate film at 20% elongation) was calculated. The results are shown in Table 1.

[0091] Similarly, the stress at 40% elongation (40% stress) was measured in the MD and TD of the substrate film, and the ratio of the stress at 40% elongation to the stress at 20% elongation in the MD (i.e., the elongation of the substrate film in the MD) and the ratio of the stress at 40% elongation to the stress at 20% elongation in the TD (i.e., the elongation of the substrate film in the TD) were calculated. The results are shown in Table 1.

[0092] Similarly, the stress at 5% elongation (5% stress) was measured in the MD and TD of the substrate film, and the ratio of the stress at 5% elongation to the stress at 40% elongation in the MD and the ratio of the stress at 5% elongation to the stress at 40% elongation in the TD were calculated. The results are shown in Table 1.

[0093] <Calculation of stress relaxation rate> The prepared substrate film was used to obtain a measurement sample having a No. 1 dumbbell shape (width 10 mm, length 120 mm). Next, the obtained measurement sample was set in a tensile tester (manufactured by Shimadzu Corporation, product name: AG-5000A) so that the distance between the grippers was 80 mm, and the sample was elongated by 25% in the MD (or TD) at a tensile speed of 300 mm / min in an environment of a temperature of 23°C and a relative humidity of 40%.

[0094] The stress when stretched by 25% (initial stress S ０ ) was measured, and the test piece was held in the elongated state for 60 seconds, and the stress after 60 seconds (post-relaxation stress S １ Then, the above-mentioned initial stress S ０ and post-relaxation stress S １ The stress relaxation rates [%] in the MD and TD of the substrate film were calculated from the difference between the values. The results are shown in Table 1.

[0095] [Equation 1] Stress relaxation rate [%] = [(initial stress S ０ - Post-relaxation stress S １ ) / initial stress S ０ ]×100 (1)

[0096] (Examples 2 to 7, Comparative Examples 1 to 4) Substrate films having the thicknesses shown in Tables 1 and 2 and a three-layer structure in which the surface layer / functional layer / surface layer were laminated in this order were obtained in the same manner as in Example 1 above, except that the composition of the resin component was changed to the composition (parts by mass) shown in Tables 1 and 2.

[0097] The biomass content of the entire substrate film was calculated, the presence or absence of a yield point was evaluated, stresses in the MD and TD were measured, and the stress relaxation rate was calculated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0098] The SS curves (stress-strain curves) in the MD and TD of the substrate film of Example 1 are shown in Figure 2. As shown in Table 1, the ratio of stress (at 5% elongation) to stress (at 40% elongation) in the MD and TD is 1.05 or less, and therefore, as shown in Figure 2, the SS curves (stress-strain curves) in the MD and TD do not have a yield point between the elongation rate of 0% and 100%.

[0099]

[0100]

[0101] As shown in Table 1, in the substrate films of Examples 1 to 7, in which the functional layer contains a 1-butene homopolymer, a pentene copolymer, and a propylene-based elastomer, and the content of the propylene-based elastomer relative to the total functional layer is 10% by mass or more and 40% by mass or less, the ratio of stress (at 5% elongation) to stress (at 40% elongation) in the MD and TD is 1.05 or less, thereby suppressing the occurrence of a yield point. Furthermore, the ratio of stress (at 40% elongation) to stress (at 20% elongation) (i.e., the elongation rate of the substrate film in the MD and TD) is 0.95 or more and 2 or less, thereby preventing necking and enabling uniform expansion, and demonstrating excellent uniform elongation. Furthermore, the stress (at 20% elongation) in the MD and TD is 7.0 MPa or more and 20 MPa or less, indicating excellent rigidity. Furthermore, the stress relaxation rate is 25% or more, indicating excellent stress relaxation.

[0102] Furthermore, as shown in Table 1, in the base films of Examples 1 to 7, at least one of the functional layer and the surface layer contains plant-derived low-density polyethylene, and the biomass content of the entire base film is 4% by mass or more and less than 49% by mass, which shows that the environmental load can be sufficiently reduced.

[0103] On the other hand, as shown in Table 2, in the substrate film of Comparative Example 1, since the functional layer and surface layer contain only a propylene-based elastomer, the ratio of stress (at 40% elongation) to stress (at 20% elongation) (i.e., the elongation rate of the substrate film in MD and TD) is less than 0.95, indicating poor uniform elongation. Furthermore, the stress (at 20% elongation) in MD and TD is less than 7.0 MPa, indicating poor rigidity. Furthermore, since the functional layer and surface layer do not contain plant-derived low-density polyethylene, it is not possible to sufficiently reduce the environmental impact.

[0104] Furthermore, as shown in Table 2, in the base film of Comparative Example 2, the biomass content of the entire base film was 49 mass% or more, so there was an excess of biomass-derived low-density polyethylene with a low degree of crystallinity, and the stress in the TD (at 20% elongation) was less than 7.0 MPa, which indicates poor rigidity.

[0105] Furthermore, as shown in Table 2, in the base film of Comparative Example 3, the functional layer and surface layer do not contain plant-derived low-density polyethylene, and therefore it is understood that the environmental load cannot be sufficiently reduced.

[0106] Furthermore, as shown in Table 4, in the base film of Comparative Example 4, the content of the propylene-based elastomer relative to the entire functional layer was greater than 40 mass%, resulting in an excess of propylene-based elastomer components with low crystallinity, and the stress in TD (at 20% elongation) was less than 7.0 MPa, indicating poor rigidity.

[0107] As described above, the present invention is suitable for a substrate film for a tape for manufacturing a semiconductor device.

[0108] 1 Base film 2 Functional layer 3 Surface layer

Claims

1. A substrate film for a semiconductor manufacturing tape having a functional layer and a surface layer provided on at least one side of the functional layer, wherein the functional layer contains a homopolymer of 1-butene, a copolymer of pentene, and an olefin-based elastomer, the content of the olefin-based elastomer in the entire functional layer is 10% by mass or more and 40% by mass or less, at least one of the functional layer and the surface layer contains an olefin-based resin derived from plants, and the biomass degree of the entire substrate film for semiconductor manufacturing tape is 4% by mass or more and less than 49% by mass.

2. The substrate film for a tape for manufacturing semiconductor devices according to claim 1, wherein the plant-derived olefin resin is a plant-derived polyethylene.

3. The substrate film for a tape for manufacturing semiconductor devices according to claim 1, wherein the olefin-based elastomer is a propylene-based elastomer.

4. The substrate film for a semiconductor manufacturing tape according to claim 1, characterized in that the content of said pentene copolymer in the entire functional layer is 10% by mass or more and 40% by mass or less.

5. The substrate film for a tape for producing semiconductors according to claim 1 or 4, wherein the pentene copolymer is a copolymer of 4-methyl-1-pentene and an α-olefin.

6. The substrate film for semiconductor manufacturing tape according to claim 1, characterized in that the surface layer contains a 1-butene homopolymer, and the content of the 1-butene homopolymer in the entire surface layer is more than 0 mass% and 30 mass% or less.

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