Base material film for semiconductor manufacturing tape

Abstract

A base material film (1) for a semiconductor manufacturing tape has a functional layer (2). The functional layer (2) contains an ionomer and an olefin-based elastomer. The ratio of stress (at 40% elongation) to stress (at 20% elongation) at -15°C is 0.95 to 2, inclusive, and the stress relaxation rate at room temperature is 25% or more.

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] Dicing tape and dicing die attach film are generally composed of an adhesive layer for fixing the wafer and a base film containing polyolefin or the like. For example, it is a random copolymer of propylene and 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 than the propylene-based random copolymer (β) and having a higher density (see, for example, Patent Document 1).

[0005] JP 2018-65327 A

[0006] However, although the substrate film described in Patent Document 1 has stress relaxation properties that allow it to replace vinyl chloride resin, it uses a semi-crystalline resin rather than an amorphous resin, and therefore necking occurs when the substrate film is stretched to form gaps between semiconductor devices, resulting in a problem of insufficient uniform elongation of the substrate film.

[0007] Furthermore, in recent years, there has been a shift to stealth dicing, which uses laser processing equipment that can reduce processing waste and narrow the cut width, and this has led to an increasing demand for base films suitable for this dicing method.In the stealth dicing method, chips are separated by expanding under low-temperature conditions (for example, −15°C), so there is a need for base films that can be stretched uniformly not only at room temperature but also at low temperatures.

[0008] The present invention has been made in view of the above problems, and has an object to provide a substrate film for a tape for semiconductor manufacturing that has excellent stress relaxation properties and uniform elongation properties at low temperatures.

[0009] In order to achieve the above object, the substrate film for a tape for semiconductor production of the present invention is a substrate film for a tape for semiconductor production that has at least a functional layer, wherein the functional layer contains an ionomer and an olefin-based elastomer, and is characterized in that the ratio of stress (at 40% elongation) to stress (at 20% elongation) at −15°C is 0.95 or more and 2 or less, and the stress relaxation rate at room temperature is 25% or more.

[0010] According to the present invention, it is possible to provide a substrate film for a tape for semiconductor manufacturing that has excellent stress relaxation properties and uniform elongation properties at low temperatures.

[0011] Fig. 1 is a cross-sectional view showing a substrate film for semiconductor manufacturing tape according to an embodiment of the present invention. Fig. 2 is an SS curve (stress-strain curve) at room temperature for the substrate film of Example 1. Fig. 3 is an SS curve (stress-strain curve) at -15°C for the substrate film of Example 1. Fig. 4 is an SS curve (stress-strain curve) at room temperature for the substrate film of Comparative Example 1. Fig. 5 is an SS curve (stress-strain curve) at -15°C for the substrate film of Comparative Example 1.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] (Functional Layer) The functional layer may contain an ionomer and an olefin-based elastomer.

[0016] <Ionomer> In the base film 1 of the present invention, the functional layer 2 contains an ionomer from the viewpoint of improving uniform elongation at low temperatures and improving stress relaxation properties that enable the dimensions of the semiconductor manufacturing tape to be maintained after expansion.

[0017] In addition, the term "ionomer" as used herein refers to a synthetic resin in which polymers are aggregated by utilizing the cohesive force of metal ions, and specifically refers to a resin in which a binary copolymer of ethylene and (meth)acrylic acid is crosslinked with metal ions, or a resin in which a terpolymer of ethylene, (meth)acrylic acid, and a (meth)acrylic acid ester is crosslinked with metal ions.

[0018] The term "(meth)acrylic acid" used herein refers to acrylic acid and / or methacrylic acid.

[0019] As the metal ions, for example, sodium ions (Na ＋ ), zinc ions (Zn ２＋ ), potassium ions (K ＋ ), lithium ion (Li ＋ ), magnesium ions (Mg ２＋ ) etc.

[0020] Examples of the (meth)acrylic acid ester include propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-methylpropyl (meth)acrylate, 2-ethylpropyl (meth)acrylate, 2-methylhexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0021] The ionomers may be used alone or in combination of two or more.

[0022] As the ionomer, for example, commercially available products such as Himilan (registered trademark) 1605 (a resin in which a binary copolymer of ethylene and (meth)acrylic acid is crosslinked with sodium ions) and Himilan (registered trademark) 1855N (a resin in which a ternary copolymer of ethylene, (meth)acrylic acid, and a (meth)acrylic acid ester is crosslinked with zinc ions) can be used.

[0023] Such ionomers have a characteristic structure in which carboxylic acid group side chains are present on the polyethylene molecular chains and some of the carboxylic acid groups are cross-linked between molecular chains by the metal ions described above, which improves the uniform elongation of the substrate film at low temperatures (-15°C). The structure also contributes to improved stress relaxation, enabling the grip ring to hold the semiconductor manufacturing tape and maintain the spacing between semiconductor devices (semiconductor chips).

[0024] Furthermore, from the viewpoint of improving uniform elongation and stress relaxation at low temperatures, the content of the ionomer in the entire functional layer 2 is preferably 10% by mass or more and 80% by mass or less, with the functional layer being 100% by mass. If the ionomer content is less than 10% by mass, the content of the ionomer that contributes to stress relaxation will decrease, which may result in a decrease in stress relaxation. If the ionomer content is more than 80% by mass, the content of the olefin elastomer or 1-butene homopolymer that contributes to uniform elongation, as described below, will decrease, which may result in a decrease in uniform elongation at room temperature as well as a decrease in uniform elongation at low temperatures.

[0025] The content of the ionomer in the entire functional layer 2 is preferably 20% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less, out of 100% by mass of the functional layer.

[0026] From the viewpoint of improving the processing stability of the substrate film, the melt mass flow rate (MFR) of the ionomer is preferably 0.5 to 5.0 g / 10 min.

[0027] The melt mass flow rate can be obtained by measuring in accordance with the provisions of JIS K7210:1999.

[0028] From the viewpoint of improving heat resistance, the melting point of the ionomer is preferably 85° C. or higher.

[0029] <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.

[0030] 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.

[0031] 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.

[0032] Furthermore, from the viewpoint of improving uniform elongation, the content of the olefin-based elastomer in the entire functional layer 2 is preferably 5% by mass or more and 50% by mass or less, based on 100% by mass of the functional layer 2. If the content of the olefin-based elastomer is more than 50% by mass, the olefin-based elastomer component with a low degree of crystallinity will be in excess, which may reduce rigidity and make it difficult to unwind the substrate and to form it into a tape, including applying a pressure-sensitive adhesive.

[0033] The content of the olefin-based elastomer in the entire functional layer 2 is preferably 10% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, and even more preferably 20% by mass or more and 30% by mass or less, out of 100% by mass of the functional layer.

[0034] 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:

[0035] <1-butene homopolymer> The functional layer 2 in the substrate film 1 of the present invention preferably contains a homopolymer obtained by polymerizing 1-butene alone as polybutene. This 1-butene homopolymer has a high molecular weight and bulky side chains, and the strong intermolecular forces caused by these bulky side chains enable it to improve the uniform extensibility of the substrate film, similar to the case of an amorphous polymer, despite being a crystalline polymer.

[0036] 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.

[0037] The "weight average molecular weight" refers to the value calculated in accordance with JIS K 7252-1:2016.

[0038] 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.

[0039] 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.

[0040] 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 more than 0% by mass and not more than 80% by mass, more preferably 10% by mass or more and not more than 60% by mass, even more preferably 20% by mass or more and not more than 60% by mass, and most preferably 20% by mass or more and not more than 40% by mass, out of 100% by mass of the functional layer.

[0041] (Surface Layer) 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 a polyolefin resin such as polyethylene or polypropylene.

[0042] The polyolefin resin referred to here refers to a homopolymer or copolymer of an olefin such as ethylene, propylene, or 1-butene, a copolymer of an olefin with a monomer such as vinyl acetate, (meth)acrylic acid, or a (meth)acrylic acid ester, and a copolymer obtained by modifying the above-mentioned monomer with a metal ion or an acid.

[0043] For example, polypropylene includes propylene homopolymers and copolymers. Among these, propylene 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 base film.

[0044] <Low-density polyethylene> The surface layer 3 is made of a polyolefin resin having a density of 0.930 g / cm ３ Preferably, the polyethylene contains low density polyethylene (LDPE) having a density of 0.930 g / cm or less. ３ In the following cases, an excessive increase in the crystallinity is suppressed and flexibility is improved, so that the isotropy of the substrate film can be improved. ３ If it is larger than this, the crystallinity increases excessively, which may result in a decrease in isotropy, and the rigidity may become too large, which may result in a decrease in the pick-up ability of the semiconductor device and damage to the semiconductor device.

[0045] From the viewpoint of improving processing stability, the density of the low-density polyethylene is 0.860 g / cm ３ It is preferable that the density is 0.880 g / cm or more. ３ More preferably, it is equal to or greater than this.

[0046] That is, the density is 0.860 g / cm ３ 0.930g / 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.

[0047] 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.

[0048] From the viewpoint of strength, linear low-density polyethylene produced using a metallocene catalyst or a Ziegler catalyst may also be used.

[0049] 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.

[0050] The melt mass flow rate can be obtained by measuring in accordance with the provisions of JIS K7210:1999.

[0051] From the above, the resin forming the base film has a density of 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.

[0052] In addition, from the viewpoint of suppressing surface adhesion, it is preferable that the content of low-density polyethylene in the entire surface layer 3 (i.e., each surface layer 3 laminated on both sides of the functional layer 2) is 70% by mass or more and 100% by mass or less out of 100% by mass of the surface layer.

[0053] The surface layer 3 of the base film 1 of the present invention may contain the above-mentioned ionomer from the viewpoint of reliably maintaining uniform elongation and stress relaxation at low temperatures. In this case, the content of the ionomer in the surface layer 3 (i.e., each of the surface layers 3 laminated on both sides of the functional layer 2) is preferably more than 0 mass% and 30 mass% or less, relative to 100 mass% of the surface layer.

[0054] Furthermore, the surface layer 3 of the base film 1 of the present invention may contain the above-mentioned 1-butene homopolymer. Despite its high molecular weight, the 1-butene homopolymer can be molded using a general-purpose extruder, and the high molecular weight component reduces the surface adhesion of the film. Therefore, when used in the surface layer, it can suppress adhesion to transport rolls when the base film is transported, as well as suppress blocking when the base film is wound up and draw resonance when the base film is molded, thereby improving the processing stability of the base film.

[0055] Furthermore, from the viewpoint of suppressing surface adhesion, 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 not more than 30 mass% of 100 mass% of the surface layer.

[0056] <Base film> In the case of a base film containing a conventional polyolefin, necking does not occur when the base film is stretched by 20%, and the film can be expanded uniformly. However, necking begins to occur when the base film is stretched by 40%, making it difficult to expand uniformly.

[0057] Therefore, in the base film 1 of the present invention, from the viewpoint of improving the uniform extensibility of the base film at low temperatures, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) at −15° C. in the mechanical axis (longitudinal) direction (hereinafter referred to as “MD”) of the base film and in the direction perpendicular thereto (hereinafter referred to as “TD”) (i.e., the elongation of the base film) is 0.95 to 2. If the elongation of the base film is greater than 2, excessive stress may increase, making it difficult to hold the expanding ring. If the elongation of the base film is less than 0.95, necking may occur, making uniform expansion difficult.

[0058] That is, if the elongation of the base film at -15°C is 0.95 or more and 2 or less, necking does not occur and uniform expansion becomes possible.

[0059] From the same viewpoint, it is also preferable that the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) at room temperature in both MD and TD (i.e., the elongation rate of the base film) is 0.95 or more and 2 or less.

[0060] That is, if the elongation of the base film at room temperature is 0.95 or more and 2 or less, necking does not occur and uniform expansion becomes possible.

[0061] The elongation percentage of the base film at room temperature and −15° C. is more preferably 1 or more and 1.80 or less, and from the viewpoint of preventing necking and ensuring uniform expansion, the elongation percentage of the base film is even more preferably 1.05 or more and 1.70 or less.

[0062] Furthermore, "room temperature" here refers to 23°C ± 2°C (temperature between 21 and 25°C).

[0063] Furthermore, in the base film 1 of the present invention, from the viewpoint of further improving the uniform extensibility of the base film, it is preferable that the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) is 1.05 or less in the MD and TD at room temperature and −15° C. If the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) is 1.05 or less, the occurrence of the yield point (the yield point during the elongation rate expansion from 0% to 100% at a tensile speed of 300 mm / min) described below can be suppressed, thereby suppressing the occurrence of necking and enabling uniform expansion.

[0064] 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 0.40 or more and less than 0.90.

[0065] Furthermore, the base film 1 of the present invention has a stress relaxation rate of 25% or more at room temperature. 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.

[0066] 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.

[0067] From the viewpoint of further improving the stress relaxation property, the stress relaxation rate at room temperature is more preferably 30% or more, and even more preferably 35% or more.

[0068] The "stress relaxation rate" referred to here can be determined by the method described in the examples below.

[0069] In addition, in the substrate film 1 of the present invention, the stress in the MD and TD at room temperature (at 20% elongation) is preferably 5.0 MPa or more and 20 MPa or less, more preferably 6.5 MPa or more and 15 MPa or less, and even more preferably 7.5 MPa or more and 13 MPa or less. If the stress is greater than 20 MPa, the rigidity becomes too large, which may reduce the pickup ability of the semiconductor device and cause damage to the semiconductor device. If the stress is less than 5.0 MPa, the rigidity becomes low, which may make it difficult to unwind the substrate in the manufacturing process of the substrate film and to form the film into a tape, including coating with an adhesive.

[0070] Furthermore, the MD and TD stresses (at 20% elongation) at low temperatures (-15°C) are preferably 10 MPa or more and 40 MPa or less, more preferably 12 MPa or more and 35 MPa or less, and even more preferably 15 MPa or more and 30 MPa or less. If the stress is greater than 40 MPa, the rigidity becomes too high, which may reduce the pickup ability of the semiconductor device and cause damage to the semiconductor device. If the stress is less than 10 MPa, the rigidity becomes low, which may make it difficult to unwind the substrate in the manufacturing process of the substrate film and to form the film into a tape, including applying an adhesive.

[0071] That is, when the stress in MD and TD (at 20% elongation) at room temperature is 5.0 MPa or more and 20 MPa or less, or when the stress in MD and TD (at 20% elongation) at −15° C. is 10 MPa or more and 40 MPa or less, it is possible to provide a substrate film having excellent rigidity that can be unwound and formed into a tape, including the application of a pressure-sensitive adhesive, in the manufacturing process of the substrate film.

[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) 1-Bu: 1-butene homopolymer, melting point: 128 ° C, density: 0.920 g / cm ３ , MFR: 0.5 g / 10 min (3) 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) (4) PP elastomer 2: propylene-based elastomer, density: 0.890 g / cm ３, MFR: 8.0 g / 10 min (230 ° C), polyethylene content: 4% (manufactured by ExxonMobil Corporation, trade name: Vistamax (registered trademark) 3588FL) (5) Ionomer 1: binary ionomer, a resin obtained by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with Na ions, melting point: 92 ° C, density: 0.940 g / cm ３ , MFR: 2.8 g / 10 min (6) Ionomer 2: Ternary ionomer, a resin obtained by crosslinking a ternary copolymer of ethylene, (meth)acrylic acid, and (meth)acrylic acid ester with Zn ions, melting point: 86°C, density: 0.960 g / cm ３ MFR: 1.0 g / 10 min

[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] <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 room temperature (23°C) and a relative humidity of 40% at a tension rate of 300 mm / min.

[0086] Similarly, the measurement sample obtained above 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 in an environment at a temperature of −15° C. at a tensile speed of 500 mm / min.

[0087] In the SS curves (stress-strain curves) in MD and TD at room temperature and -15°C, 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 rated as ⊚, 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 rated as ◯, and those in which a yield point was observed during the elongation rate from 0% to 100% (necking occurred and uniform expansion was impossible) were rated as ×. The results are shown in Table 1.

[0088] <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 room temperature (23°C) and a relative humidity of 40% at a tension speed of 300 mm / min.

[0089] Similarly, the measurement sample obtained above 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 in an environment at a temperature of −15° C. at a tensile speed of 500 mm / min.

[0090] The stress at 20% elongation (20% stress) in the MD and TD of the substrate film was measured at room temperature and at −15° C. The results are shown in Table 1.

[0091] Similarly, the stress (40% stress) of the substrate film at 40% elongation in the MD and TD was measured at room temperature and −15° C., 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 at room temperature and −15° C. The results are shown in Table 1.

[0092] Similarly, the stress (5% stress) at 5% elongation in the MD and TD of the substrate film was measured at room temperature and −15° C., 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 at room temperature and −15° C. The results are shown in Table 1.

[0093] <Calculation of stress relaxation rate> The produced 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 room temperature (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 [%] of the substrate film in the MD and TD at room temperature were calculated from the difference between the values ​​of the stress relaxation rates [%] and the stress relaxation rates [%] of the substrate film in the MD and TD at room temperature. 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 13, Comparative Examples 1 to 6 Substrate films having the thicknesses shown in Tables 1 to 3 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 described above, except that the composition of the resin component was changed to the composition (parts by mass) shown in Tables 1 to 3.

[0097] Then, the presence or absence of a yield point was evaluated, stresses in 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 to 3.

[0098] 2 and 3 show the SS curves (stress-strain curves at room temperature and -15°C) in the MD and TD of the substrate film of Example 1. As shown in Table 1, the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) at room temperature and -15°C in the MD and TD is 1.05 or less, and therefore, as shown in Figures 2 and 3, the SS curves (stress-strain curves at room temperature and -15°C) in the MD and TD do not have a yield point between the elongation rate of 0% and 100%.

[0099] 4 and 5 show the SS curves (stress-strain curves at room temperature and -15°C) in the MD and TD of the substrate film of Comparative Example 1. As shown in Table 3, the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) at -15°C in the MD and TD is greater than 1.05, and therefore, as shown in Fig. 5, the SS curves (stress-strain curves at -15°C) in the MD and TD have a yield point between the elongation rate of 0% and 100%.

[0100]

[0101]

[0102]

[0103] As shown in Tables 1 and 2, in the substrate films of Examples 1 to 13, the ratio of stress (at 5% elongation) to stress (at 40% elongation) in the MD and TD at room temperature and -15°C was 1.05 or less, thereby suppressing the occurrence of yield points at room temperature and -15°C. The ratio of stress (at 40% elongation) to stress (at 20% elongation) at room temperature and -15°C (i.e., the elongation of the substrate film in the MD and TD) was 0.95 to 2, thereby preventing necking at room temperature and -15°C, enabling uniform expansion and demonstrating excellent uniform elongation. Furthermore, the stress relaxation rate in the MD and TD was 25% or more at room temperature, indicating excellent stress relaxation properties at room temperature. Furthermore, the stress (at 20% elongation) in the MD and TD at room temperature was 5.0 MPa to 20 MPa, indicating excellent rigidity at room temperature. Furthermore, at -15°C, the stress in MD and TD (at 20% elongation) is 10 MPa or more and 40 MPa or less, and therefore it is clear that the rigidity at -15°C is excellent.

[0104] On the other hand, as shown in Table 3, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) (i.e., the elongation of the substrate film in MD and TD) of the substrate film of Comparative Example 1 at room temperature and -15°C was less than 0.95, indicating poor uniform elongation. Furthermore, the ratio of the stress (at 5% elongation) to the stress (at 40% elongation) in MD and TD at -15°C was greater than 1.05, indicating that the occurrence of the yield point at -15°C could not be suppressed, as described above.

[0105] As shown in Table 3, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) at room temperature in both MD and TD (i.e., the elongation of the base film in MD and TD) was less than 0.95, indicating poor uniform elongation. Furthermore, the ratio of the stress (at 40% elongation) to the stress (at 20% elongation) at −15° C. in TD (i.e., the elongation of the base film in TD) was less than 0.95, indicating poor uniform elongation.

[0106] Furthermore, as shown in Table 3, in the substrate films of Comparative Examples 3 and 4, the stress relaxation rates in MD and TD were less than 25% at room temperature, indicating poor stress relaxation properties at room temperature.

[0107] Furthermore, as shown in Table 3, in the substrate film of Comparative Example 5, the stress in the TD (at 20% elongation) was less than 5.0 MPa at room temperature, indicating poor rigidity at room temperature. Furthermore, the stress in the TD (at 20% elongation) was less than 10 MPa at −15° C., indicating poor rigidity at −15° C. Furthermore, the stress relaxation rate in the TD was less than 25% at room temperature, indicating poor stress relaxation property at room temperature.

[0108] Furthermore, as shown in Table 3, the substrate film of Comparative Example 6 had high rigidity and low flexibility, and the film broke in the TD of the substrate film (at 40% elongation at -15°C). Therefore, it is clear that the substrate film of Comparative Example 6 cannot suppress the occurrence of a yield point at -15°C and has poor uniform elongation. Furthermore, the stress relaxation rates in the MD and TD at room temperature were less than 25%, indicating poor stress relaxation at room temperature.

[0109] As described above, the present invention is suitable for a substrate film for a tape for manufacturing a semiconductor device.

[0110] 1 Base film 2 Functional layer 3 Surface layer

Claims

1. A substrate film for a semiconductor manufacturing tape having at least a functional layer, wherein the functional layer contains an ionomer and an olefin-based elastomer, and the ratio of stress (at 40% elongation) to stress (at 20% elongation) at -15°C is 0.95 or more and 2 or less, and the stress relaxation rate at room temperature is 25% or more.

2. The substrate film for a tape for semiconductor manufacturing according to claim 1, characterized in that the ratio of stress (at 5% elongation) to stress (at 40% elongation) at -15°C is 1.05 or less.

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