Substrate film for semiconductor manufacturing tape

Abstract

The semiconductor manufacturing tape base material film (1) of the present application has a functional layer (2) containing an ionomer and an olefin-based elastomer. The content of the ionomer is 10 mass% or more and 80 mass% or less with respect to the entire functional layer (2), and the content of the olefin-based elastomer is 5 mass% or more and 50 mass% or less with respect to the entire functional layer (2).

Description

Technical Field

[0001] This invention relates to a substrate film (hereinafter sometimes simply referred to as "substrate film") used in semiconductor manufacturing. Background Technology

[0002] As a method for manufacturing semiconductor devices such as IC chips, a widely used method is as follows: On a semiconductor manufacturing tape (dicing tape) for wafer fabrication, wafer circuits formed on a roughly circular semiconductor wafer are divided by cutting to obtain individual semiconductor devices. Furthermore, after cutting, for example, the dicing tape is stretched to create gaps (i.e., expansion) between the semiconductor devices, and then each semiconductor device is picked up by a robot or the like.

[0003] In addition, as a semiconductor manufacturing tape for wafers, a diced chip film (DDAF) with an adhesive layer stacked on the adhesive layer of the aforementioned dicing tape is used. After the wafer circuit is divided by cutting on the diced chip film, the diced chip film is stretched to form gaps between semiconductor devices. Then, the adhesive layer is photocured. In the state of adhesive layer bonding, the semiconductor devices are peeled off from the adhesive layer and picked up.

[0004] Cutting tapes and chip-cutting films typically consist of an adhesive layer that holds the wafer in place and a substrate film containing polyolefins, etc. For example, a substrate film has been proposed that consists of a laminate of an intermediate layer and a surface layer. The intermediate layer is mainly composed of a propylene-based random copolymer (β) of propylene and ethylene and / or α-olefins having 4 to 8 carbon atoms. In the propylene-based random copolymer (β), the content of ethylene and / or α-olefins having 4 to 8 carbon atoms is 6% by weight or more, and the density measured according to ASTM D1505 is 885 kg / m³ or less. The surface layer is laminated on both sides of the intermediate layer and is mainly composed of a propylene-based random copolymer (α) with less ethylene and / or α-olefins having 4 to 8 carbon atoms and a higher density than the propylene-based random copolymer (β) (for example, see Patent Document 1).

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-65327 Summary of the Invention The problem that the invention aims to solve However, in the substrate film described in the aforementioned Patent Document 1, although it has stress relaxation properties that can replace vinyl chloride resin, it uses a semi-crystalline resin that is not amorphous. Therefore, necking occurs when the substrate film is stretched and gaps are formed between semiconductor devices, resulting in insufficient uniform elongation of the substrate film.

[0006] Furthermore, in recent years, the demand for substrate films suitable for stealth dicing (which can suppress processing debris and narrow the dicing width using laser processing equipment) has increased due to the shift towards stealth dicing. In stealth dicing, chip dicing is performed by expansion at low temperatures (e.g., -15°C), thus requiring substrate films that can elongate uniformly not only at room temperature but also at low temperatures.

[0007] Therefore, the present invention was made in view of the above-mentioned problems, and its object is to provide a substrate film for semiconductor manufacturing tape with excellent stress relaxation properties and excellent uniform elongation at both room temperature and low temperature.

[0008] Problem-solving methods To achieve the above objectives, the semiconductor manufacturing substrate film of the present invention is characterized by having at least a functional layer comprising an ionomer and an olefin-based elastomer, wherein the content of the ionomer is 10% by mass or more and 80% by mass or less relative to the functional layer as a whole, and the content of the olefin-based elastomer is 5% by mass or more and 50% by mass or less relative to the functional layer as a whole.

[0009] Invention Effects According to the present invention, a substrate film for semiconductor manufacturing tapes can be provided that exhibits excellent stress relaxation properties and excellent uniform elongation at both room temperature and low temperature. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view showing a substrate film for semiconductor manufacturing according to an embodiment of the present invention.

[0011] Figure 2 This is the SS curve (stress-strain curve) of the substrate film of Example 1 at room temperature.

[0012] Figure 3 This is the SS curve (stress-strain curve) of the substrate film of Example 1 at -15°C.

[0013] Figure 4 The SS curve (stress-strain curve) of the substrate film of Comparative Example 1 at room temperature is shown.

[0014] Figure 5 The SS curve (stress-strain curve) of the substrate film of Comparative Example 1 at -15°C is shown. Detailed Implementation

[0015] The semiconductor manufacturing substrate film of the present invention will now be described in detail. Furthermore, the present invention is not limited to the following embodiments; appropriate modifications and applications can be made without altering the spirit of the invention.

[0016] The substrate film of the present invention is composed of a laminate of a functional layer (intermediate layer) and a surface layer disposed on at least one side of the functional layer.

[0017] As a substrate film having this multilayer structure, for example, Figure 1 As shown, a substrate film 1 can be described as having a three-layer structure consisting of a functional layer 2 and a surface layer 3 stacked on both sides of the functional layer 2, and having the surface layer / functional layer / surface layer stacked sequentially.

[0018] (Functional layer) As functional layers, examples include functional layers containing ionomers and olefin-based elastomers.

[0019] <Isolates> In the substrate film 1 of the present invention, from the viewpoint of improving uniform elongation at low temperatures and improving stress relaxation of maintaining the semiconductor manufacturing strip size after expansion, the functional layer 2 contains an ionomer.

[0020] In addition, the ionomer in this invention refers to a synthetic resin that uses the cohesive force based on metal ions to make polymers into aggregates. Specifically, it refers to a resin formed by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with metal ions, or a resin formed by crosslinking a terpolymer of ethylene, (meth)acrylic acid and (meth)acrylate with metal ions.

[0021] Additionally, "(meth)acrylic acid" as used here refers to acrylic acid and / or methacrylic acid.

[0022] Examples of the aforementioned metal ions include sodium ions (Na+). + ), zinc ions (Zn²) + ), potassium ions (K) + Lithium ion (Li) + ), magnesium ions (Mg²) + )wait.

[0023] In addition, examples of the aforementioned (meth)acrylates 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.

[0024] In addition, one type of ionomer can be used alone, or two or more types can be used together.

[0025] In addition, as ionomers, commercially available products such as Himilan 1605 (a resin formed by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with Na ions) and Himilan 1855N (a resin formed by crosslinking a terpolymer of ethylene, (meth)acrylic acid and (meth)acrylate with Zn ions) can be used.

[0026] Furthermore, this ionomer has carboxylic acid side chains on the polyethylene molecular chain, and a portion of these carboxylic acid groups are cross-linked between the molecular chains by the aforementioned metal ions, thus improving the uniform elongation of the substrate film at low temperatures (-15°C). Additionally, this structure also helps improve stress relaxation, enabling the use of clamping rings to hold the semiconductor manufacturing tape and maintain the spacing between individual semiconductor devices (semiconductor chips).

[0027] Furthermore, from the viewpoint of improving stress relaxation and uniform elongation at low temperatures, the ionomer content, relative to the functional layer 2 as a whole, is between 10% and 80% by mass in 100% by mass of the functional layer. When the ionomer content is less than 10% by mass, the content of ionomers that contribute to stress relaxation decreases, thus reducing stress relaxation; when it is greater than 80% by mass, the content of olefin-based elastomers and 1-butene homopolymers that contribute to uniform elongation (described later) decreases, thus reducing uniform elongation at room temperature, and also reducing uniform elongation at low temperatures.

[0028] Furthermore, relative to the functional layer 2 as a whole, the content of ionomer in the functional layer 100% by mass is preferably 20% or more and 80% or less by mass, more preferably 40% or more and 80% or less by mass, and even more preferably 40% or more and 60% or less by mass.

[0029] Furthermore, 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.

[0030] In addition, the above-mentioned melt mass flow rate was obtained by measurement in accordance with the provisions of JIS K7210:1999.

[0031] In addition, from the viewpoint of improving heat resistance, the melting point of the ionomer is preferably above 85°C.

[0032] <Olefin-based elastomers> Furthermore, in the substrate 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 conforming to the definition of elastomer terminology in JIS K 6200. More specifically, materials composed of amorphous or low-crystallinity α-olefin copolymers belong to olefin-based elastomers; elastomers based on polyethylene are called ethylene-based elastomers, and elastomers based on polypropylene are called propylene-based elastomers. For example, as an ethylene-based elastomer, the trade name "Tafmer (registered trademark)" manufactured by Mitsui Chemicals Co., Ltd. can be cited; as a propylene-based elastomer, the trade name "Vistamaxx (registered trademark)" manufactured by ExxonMobil Co., Ltd. can be cited.

[0033] In addition, when using propylene-based elastomers, from the viewpoint of improving flexibility, the content of polyethylene in 100% propylene-based elastomers is preferably 9% or more and 30% or less, relative to the overall propylene-based elastomer.

[0034] Furthermore, by using such olefin-based elastomers, crystallinity can be reduced and the formation of yield point can be suppressed, thereby improving the uniform elongation of the substrate film.

[0035] Furthermore, from the viewpoint of improving uniform elongation, the content of olefin-based elastomers in the functional layer 2 as a whole is between 5% and 50% by mass in 100% by mass of the functional layer. When the content of olefin-based elastomers exceeds 50% by mass, there is an excess of olefin-based elastomer components with low crystallinity, which reduces rigidity and sometimes makes unwinding of the substrate and tape processing, including coating adhesives, difficult.

[0036] In addition, relative to the functional layer 2 as a whole, the content of olefin-based elastomer in the functional layer 100% by mass 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.

[0037] Furthermore, from the viewpoint of further improving uniform elongation, the density of the olefin-based elastomer is preferably 0.850 to 0.900 g / cm³, more preferably 0.860 to 0.890 g / cm³.

[0038] <Homopolymer of 1-Butene> In the functional layer 2 of the substrate film 1 of the present invention, polybutene is preferably contained as a homopolymer formed by polymerizing 1-butene alone. The homopolymer of 1-butene has a high molecular weight and has large side chains. Due to the strong intermolecular forces brought about by the large side chains, even though it is a crystalline polymer, it can improve the uniform elongation of the substrate film in the same way as in the amorphous case.

[0039] In addition, the homopolymer of 1-butene used in this invention can be a homopolymer with a weight average molecular weight (Mw) of about 500,000 to 1,500,000.

[0040] In addition, the aforementioned "weight-average molecular weight" refers to the value calculated according to JIS K 7252-1:2016.

[0041] Furthermore, the homopolymer of 1-butene used in this invention has low surface adhesion due to its high molecular weight, and it also has high rigidity compared to amorphous polyolefins. Therefore, it can provide a high-rigidity substrate film that can be unwound and tape-processed, including adhesive coating, during the substrate film manufacturing process.

[0042] In summary, by using homopolymers of 1-butene as the resin for forming the substrate film, the uniform elongation and rigidity of the substrate film can be improved.

[0043] Furthermore, from the viewpoint of improving uniform elongation and rigidity, the content of 1-butene homopolymer in the functional layer 100% by mass is preferably greater than 0% by mass and less than 80% by mass, more preferably more than 10% by mass and less than 60% by mass, further preferably more than 20% by mass and less than 60% by mass, and most preferably more than 20% by mass and less than 40% by mass.

[0044] (Surface layer) Next, the surface layer 3 in the substrate film 1 of the present invention will be described. For example, a surface layer containing a polyolefin resin such as polyethylene or polypropylene can be used as the surface layer 3.

[0045] In addition, the polyolefin resins mentioned here refer to homopolymers and copolymers of olefins such as ethylene, propylene, and 1-butene, copolymers of monomers such as vinyl acetate, (meth)acrylic acid, and (meth)acrylate with olefins, and copolymers of the above monomers modified with metal ions or acids.

[0046] For example, examples of polypropylene include homopolymers and copolymers of propylene. Among these, homopolymers of propylene are homopolymer polypropylenes formed by polymerizing propylene individually. These homopolymers exhibit high stereoregularity, resulting in high crystallinity that contributes to a high melting point and thus excellent heat resistance. Furthermore, due to their high crystallinity, they possess high rigidity, but by blending with linear low-density polyethylene, flexibility that contributes to the spreadability of the substrate film can be achieved.

[0047] Low-density polyethylene The surface layer 3 preferably contains low-density polyethylene (LDPE) with a density of 0.930 g / cm³ or less in a polyolefin resin. A density of 0.930 g / cm³ or less can suppress excessive crystallinity, improve flexibility, and thus enhance the isotropy of the substrate film. Conversely, when the density exceeds 0.930 g / cm³, excessive crystallinity occurs, sometimes reducing isotropy. Furthermore, excessive rigidity reduces the pick-up capability of semiconductor devices, sometimes leading to semiconductor device breakage.

[0048] Furthermore, from the viewpoint of improving processing stability, the density of low-density polyethylene is preferably 0.860 g / cm³ or higher, and more preferably 0.880 g / cm³ or higher.

[0049] That is, low-density polyethylene with a density of 0.860 g / cm³ or higher and 0.930 g / cm³ or lower has low surface adhesion. Therefore, when it is used as a surface layer, it can suppress adhesion to the conveyor rollers during the transport of the substrate film and suppress adhesion during the winding of the substrate film, thereby improving the processing stability of the substrate film.

[0050] In addition, in low-density polyethylene, linear low-density polyethylene (LLDPE) has side chain branches in the linear structure of high-density polyethylene, so its crystallinity is not too high and its flexibility is excellent compared with high-density polyethylene.

[0051] Alternatively, from a strength perspective, linear low-density polyethylene manufactured using metallocene catalysts or Ziegler catalysts can also be used.

[0052] Furthermore, the melt flow rate (MFR) of linear 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 flow rate (MFR) is 0.5 g / 10 min or higher, the molecular weight is not too large, which can improve flexibility and processability; when it is 7.5 g / 10 min or lower, the molecular weight is not too small, which can improve processing stability.

[0053] In addition, the above-mentioned melt mass flow rate was obtained by measurement in accordance with the provisions of JIS K7210:1999.

[0054] In summary, by using low-density polyethylene with a density of less than 0.93 g / cm³ as the resin for forming the substrate film, the flexibility and isotropy of the substrate film can be improved.

[0055] Furthermore, from the viewpoint of suppressing surface adhesion, the content of low-density polyethylene in the surface layer 3 (i.e., each surface layer 3 stacked on both sides of the functional layer 2) is preferably 70% or more and 100% or less in 100% by mass of the surface layer.

[0056] Furthermore, from the viewpoint of reliably maintaining uniform elongation and stress relaxation at low temperatures, the surface layer 3 in the substrate film 1 of the present invention may also contain the aforementioned ionomer. In this case, the ionomer content in the surface layer 3 (i.e., each surface layer 3 stacked on both sides of the functional layer 2) is preferably greater than 0% and less than 30% by mass in 100% by mass of the surface layer.

[0057] Furthermore, the surface layer 3 of the substrate film 1 of the present invention may also contain the above-mentioned homopolymer of 1-butene. Although the homopolymer of 1-butene has a high molecular weight, it can be formed using a general extruder, and because the high molecular weight component results in low surface adhesion of the film, when used as a surface layer, it can suppress adhesion to the transport rollers during transport of the substrate film, and can suppress adhesion during substrate film winding and draw resonance during substrate film forming, thereby improving the processing stability of the substrate film.

[0058] Furthermore, from the viewpoint of suppressing surface adhesion, the homopolymer content of 1-butene in the surface layer 3 (i.e., each surface layer 3 stacked on both sides of the functional layer 2) is preferably greater than 0% and less than 30% by mass in 100% by mass of the surface layer.

[0059] <Substrate Film> In the substrate film 1 of the present invention, at room temperature, the stress (when elongation is 20%) in the mechanical axis (length) direction (hereinafter referred to as "MD") and the direction orthogonal to it (hereinafter referred to as "TD") of the substrate film 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. When the stress is greater than 20 MPa, the rigidity becomes too high, thus reducing the pick-up capability of the semiconductor device and sometimes causing the semiconductor device to break; when the stress is less than 5.0 MPa, the rigidity becomes low, thus making it difficult to unwind the substrate in the substrate film manufacturing process, and sometimes making the tape processing, including the coating of adhesive, difficult.

[0060] Furthermore, the stress (at 20% elongation) of the MD and TD at low temperature (-15°C) is 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. When the stress is greater than 40 MPa, the rigidity becomes too high, thus reducing the pick-up capability of the semiconductor device and sometimes causing damage to the semiconductor device; when the stress is less than 10 MPa, the rigidity becomes low, thus making it difficult to unwind the substrate during the substrate film manufacturing process, and sometimes making tape processing, including the application of adhesive, difficult.

[0061] That is, when the stress (with 20% elongation) of MD and TD at room temperature is 5.0 MPa or more and 20 MPa or less, or when the stress (with 20% elongation) of MD and TD at -15℃ is 10 MPa or more and 40 MPa or less, a substrate film with excellent rigidity can be provided that allows for substrate unwinding and tape processing including adhesive coating during the substrate film manufacturing process.

[0062] In addition, "normal temperature" as mentioned here refers to 23℃±2℃ (temperatures of 21~25℃).

[0063] In addition, in the case of conventional polyolefin-containing substrate films, no necking occurs when the substrate film is stretched by 20%, and it can expand uniformly. However, there is a problem that necking begins to occur when the substrate film is stretched by 40%, making it difficult to expand uniformly.

[0064] Therefore, in the substrate film 1 of the present invention, from the viewpoint of improving the uniform elongation of the substrate film, under MD and TD conditions, the ratio of stress (when elongated by 40%) to stress (when elongated by 20%) at room temperature and -15°C (i.e., the elongation of the substrate film) is preferably 0.95 or more and 2 or less. When the elongation of the substrate film is greater than 2, excessive stress increase occurs, and it is sometimes difficult to maintain the expansion ring; when the elongation of the substrate film is less than 0.95, necking occurs, and it is sometimes difficult to expand uniformly.

[0065] That is, if the elongation of the substrate film is above 0.95 and below 2, necking will not occur and it can expand uniformly.

[0066] Furthermore, the elongation of the substrate film is more preferably 1 or more and 1.80 or less. From the viewpoint of reliably achieving uniform expansion without necking, the elongation of the substrate film is even more preferably 1.05 or more and 1.70 or less.

[0067] Furthermore, in the substrate film 1 of the present invention, from the viewpoint of further improving the uniform elongation of the substrate film, under MD and TD conditions, the ratio of stress (when elongation is 5%) to stress (when elongation is 40%) at room temperature and -15°C is preferably 1.05 or less. If the ratio of stress (when elongation is 5%) to stress (when elongation is 40%) is 1.05 or less, the generation of the yield point (the yield point during the elongation from 0% to 100% under the condition of a tensile speed of 300 mm / min) can be suppressed, thus the generation of necking can be suppressed, and uniform expansion can be achieved.

[0068] Furthermore, the ratio of stress (when elongation is 5%) to stress (when elongation is 40%) is more preferably 0.40 or more and 1.05 or less. From the viewpoint of preventing necking and reliably achieving uniform expansion, the ratio of stress (when elongation is 5%) to stress (when elongation is 40%) is further preferably 0.40 or more and less than 0.90.

[0069] Furthermore, in the substrate film 1 of the present invention, the stress relaxation rate at room temperature is preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more. When the stress relaxation rate is less than 25%, the stress absorption performance is poor, and therefore it is sometimes difficult to maintain the dimensions of the semiconductor manufacturing strip.

[0070] That is, when the stress relaxation rate is above 25%, it can maintain the size of the semiconductor manufacturing strip and provide a substrate film for semiconductor manufacturing strip with excellent stress relaxation properties.

[0071] In addition, the “stress relaxation rate” mentioned here can be obtained by the method described in the embodiments described later.

[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 processability is improved; if the thickness is 300 μm or less, the flexibility (expandability) is improved. Furthermore, 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] Furthermore, in the case of a substrate film having a three-layer structure of surface layer / functional layer / surface layer stacked sequentially, the thickness of the surface layer is not particularly limited, but is preferably 2 to 60 μm, more preferably 4 to 40 μm. Similarly, the thickness of the functional layer is not particularly limited, but is preferably 40 to 120 μm, more preferably 50 to 80 μm.

[0074] In addition, for example, in the case of a substrate film having a three-layer structure of surface layer / functional layer / surface layer stacked in sequence, from the viewpoint of processability and low cost, the proportion of functional layer is preferably 40 to 95% relative to the overall substrate film, more preferably 50 to 90%.

[0075] <Manufacturing Method> For example, manufacturing Figure 1 When preparing a substrate film 1 with a three-layer structure of surface layer / functional layer / surface layer stacked sequentially, the resin material for forming the surface layer and the resin material for forming the functional layer are first prepared.

[0076] Next, using one of three three-layer co-extruders equipped with a T-die, the resin material for forming the surface layer and the resin material for forming the functional layer are simultaneously extruded at a predetermined temperature, thereby manufacturing the substrate film 1 of the present invention, which has a multilayer structure, consisting of a functional layer 2 and a surface layer 3 laminated on both sides of the functional layer 2. Alternatively, the substrate film of the present invention can also be manufactured by known calendering or blow molding methods.

[0077] <Other methods> The substrate film 1 of the present invention may also contain various additives. As additives, known additives commonly used in semiconductor manufacturing can be used, such as crosslinking aids, antistatic agents, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, anti-blocking agents, colorants, nucleating agents, processing aids, etc. Furthermore, these additives may be used individually or in combination of two or more.

[0078] In addition, as a crosslinking aid, for example, triallyl isocyanurate, when the substrate film contains a crosslinking aid, the content of the crosslinking aid in the substrate film is preferably 0.05 to 5 parts by mass relative to 100 parts by mass of the resin forming the substrate film, more preferably 1 to 3 parts by mass.

[0079] Furthermore, the example described is a substrate film with a three-layer structure having a surface layer / functional layer / surface layer stacked sequentially. However, the substrate film of the present invention with a multi-layer structure is not limited to a three-layer structure as long as the above-mentioned functional layer is provided. For example, it can also have a five-layer structure having a surface layer / functional layer / functional layer / functional layer / surface layer stacked sequentially.

[0080] Furthermore, in the above embodiment, a substrate film 1 with a three-layer structure of surface layer / functional layer / surface layer stacked in sequence was described as an example, but the substrate film of the present invention may also be a substrate film with a single-layer structure consisting only of the above-mentioned functional layer 2.

[0081] At this point, firstly, a resin material for forming the functional layer is prepared. Then, using one of three three-layer co-extruders equipped with a T-die, the resin material for forming the functional layer is extruded at a predetermined temperature, thereby producing a substrate film with a single-layer structure consisting only of functional layer 2. Alternatively, similar to the above embodiment, the substrate film can also be manufactured using known calendering or blow molding methods.

[0082] Example The present invention will now be described based on embodiments. However, the present invention is not limited to these embodiments, and modifications and variations can be made to these embodiments based on the spirit of the present invention. Such modifications and variations are not excluded from the scope of the present invention.

[0083] The materials used to make the substrate film are shown below.

[0084] (1) LLDPE: linear low-density polyethylene, melting point: 121℃, density: 0.922g / cm³, MFR: 1.6g / 10min (2) 1-Bu: Homopolymer of 1-butene, melting point: 128℃, density: 0.920 g / cm³, MFR: 0.5 g / 10 min (3) PP elastomer 1: Acrylic elastomer, density: 0.862 g / cm³, MFR: 3.0 g / 10 minutes (230℃), polyethylene content: 16% (manufactured by ExxonMobil, trade name: Vistamaxx (registered trademark) 6102FL) (4) PP elastomer 2: Acrylic elastomer, density: 0.890 g / cm³, MFR: 8.0 g / 10 minutes (230°C), polyethylene content: 4% (manufactured by ExxonMobil, trade name: Vistamaxx (registered trademark) 3588FL) (5) Ionomer 1: A binary ionomer, a resin formed by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with Na ions, melting point: 92℃, density: 0.940 g / cm³, MFR: 2.8 g / 10 min (6) Ionomer 2: A ternary ionomer, a resin formed by crosslinking ethylene with (meth)acrylic acid and (meth)acrylate using Zn ions, melting point: 86℃, density: 0.960 g / cm³, MFR: 1.0 g / 10 min (Example 1) <Fabrication of Substrate Film> First, the materials shown in Table 1 are mixed to prepare a surface layer forming resin material and a functional layer forming resin material having the composition (parts by mass) shown in Table 1. Next, using three three-layer co-extruders, the resin material is simultaneously extruded using a T-die at a die temperature of 180–230°C and a cooling roller temperature of 30°C, thereby obtaining a substrate film with the thickness shown in Table 1 and having a three-layer structure of surface layer / functional layer / surface layer stacked sequentially.

[0085] <Evaluation of the presence or absence of a yield point> Using the prepared substrate film, a test sample was obtained according to JIS K7161-2:2014. Next, the obtained test sample was mounted on a tensile testing machine (Shimadzu Corporation, trade name: AG-5000A) with a clamp spacing of 40 mm, and a tensile test was conducted at a tensile speed of 300 mm / min under ambient temperature (23°C) and relative humidity of 40%, according to JIS K7161-2:2014.

[0086] Similarly, the test samples obtained above were mounted on a tensile testing machine (manufactured by Shimadzu Corporation, trade name: AG-5000A) with a clamp spacing of 40 mm, and tensile tests were performed at a tensile speed of 500 mm / min in an environment with a temperature of -15°C, according to JIS K7161-2:2014.

[0087] Then, in the SS curves (stress-strain curves) of MD and TD at room temperature and -15℃, samples that did not reach the yield point during elongation from 0% to 100% (samples that did not exhibit necking and could reliably and uniformly expand) were marked with ◎, samples that almost did not reach the yield point during elongation from 0% to 100% (samples that suppressed necking and could expand approximately uniformly) were marked with ○, and samples that reached the yield point during elongation from 0% to 100% (samples that exhibited necking and could not expand uniformly) were marked with ×. The results are shown in Table 1.

[0088] <Stress Measurement under MD and TD> Using the prepared substrate film, a test sample was obtained according to JIS K7161-2:2014. Next, the obtained test sample was mounted on a tensile testing machine (Shimadzu Corporation, trade name: AG-5000A) with a clamp spacing of 40 mm, and a tensile test was conducted at a tensile speed of 300 mm / min under ambient temperature (23°C) and relative humidity of 40%, according to JIS K7161-2:2014.

[0089] Similarly, the test samples obtained above were mounted on a tensile testing machine (manufactured by Shimadzu Corporation, trade name: AG-5000A) with a clamp spacing of 40 mm, and tensile tests were performed at a tensile speed of 500 mm / min in an environment with a temperature of -15°C, according to JIS K7161-2:2014.

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

[0091] Similarly, the stress at 40% elongation (MD) and TD of the substrate film at room temperature and -15°C were measured. Furthermore, at room temperature and -15°C, the ratio of stress at 40% elongation (MD) to stress at 20% elongation (i.e., the elongation of the substrate film at MD) and the ratio of stress at 40% elongation (TD) to stress at 20% elongation (i.e., the elongation of the substrate film at TD) were calculated. The results are shown in Table 1.

[0092] Similarly, the stress (5% stress) at 5% elongation of the MD and TD of the substrate film was measured at room temperature and -15°C. The ratio of the stress at 5% elongation to the stress at 40% elongation under MD and the ratio of the stress at 5% elongation to the stress at 40% elongation under TD were calculated at room temperature and -15°C. The results are shown in Table 1.

[0093] <Calculation of stress relaxation rate> Using the prepared substrate film, a test sample with a dumbbell shape (10 mm wide and 120 mm long) was obtained. Next, the obtained test sample was mounted on a tensile testing machine (Shimadzu Corporation, trade name: AG-5000A) with a clamp spacing of 80 mm. Under ambient temperature (23°C) and relative humidity of 40%, the sample was stretched by 25% along the MD (or TD) direction at a tensile speed of 300 mm / min.

[0094] Then, the stress at 25% elongation (initial stress S0) was measured, and the elongated state of the test piece was maintained for 60 seconds, and the stress after 60 seconds was measured (relaxed stress S1). Then, using the following formula (1), the stress relaxation rate [%] of the substrate film MD and TD at room temperature was calculated based on the difference between the initial stress S0 and the relaxed stress S1. The above results are shown in Table 1.

[0095] Stress relaxation rate [%] = [(initial stress S0 - relaxed stress S1) / initial stress S0] × 100 (1) (Examples 2-13, Comparative Examples 1-6) Except for changing the composition of the resin component to the composition (parts by mass) shown in Tables 1 to 3, the same procedure as in Example 1 above was followed to obtain a substrate film with the thickness shown in Tables 1 to 3 and having a three-layer structure of surface layer / functional layer / surface layer stacked in sequence.

[0096] Then, the same procedure as in Example 1 above was followed to evaluate the presence or absence of the yield point, measure the stress under MD and TD, and calculate the stress relaxation rate. The results are shown in Tables 1 to 3.

[0097] In addition, the SS curves (stress-strain curves at room temperature and -15°C) of MD and TD in the substrate film of Example 1 are shown in Figures 2-3 As shown in Table 1, under MD and TD conditions, at room temperature and -15℃, the ratio of stress (at 5% elongation) to stress (at 40% elongation) is below 1.05. Therefore, as Figures 2-3 As shown, in the SS curves (stress-strain curves at room temperature and -15℃) of MD and TD, it can be seen that there is no yield point during the elongation from 0% to 100%.

[0098] In addition, the SS curves (stress-strain curves at room temperature and -15°C) of MD and TD in the substrate film of Comparative Example 1 are shown below. Figures 4-5 As shown in Table 3, under MD and TD conditions, the ratio of stress (at 5% elongation) to stress (at 40% elongation) at -15℃ is greater than 1.05. Therefore, as... Figure 5 As shown in the SS curves (stress-strain curves at -15℃) of MD and TD, it can be seen that there is a yield point during the elongation from 0% to 100%.

[0099] Table 1

[0100] Table 2

[0101] Table 3

[0102] As shown in Tables 1-2, in the substrate films of Examples 1-13 (the functional layer contains ionomers and acrylic elastomers; the ionomer content is 10% by mass or more and 80% by mass or less relative to the overall functional layer, and the acrylic elastomer content is 5% by mass or more and 50% by mass or less relative to the overall functional layer), under MD and TD conditions, the stress ratio (when elongated by 5%) to stress (when elongated by 40%) at room temperature and -15°C is 1.05 or less, thus suppressing the formation of yield points at room temperature and -15°C; the stress ratio (when elongated by 40%) to stress (when elongated by 20%) at room temperature and -15°C (i.e., the elongation of the substrate film under MD and TD conditions) is 0.95 or more and 2 or less, thus preventing necking at room temperature and -15°C and enabling uniform expansion, indicating excellent uniform elongation. Furthermore, at room temperature, the stress relaxation rate under MD and TD conditions is 25% or more, indicating excellent stress relaxation properties at room temperature. Furthermore, at room temperature, the stress (with 20% elongation) under MD and TD is above 5.0 MPa and below 20 MPa, indicating excellent rigidity at room temperature. Additionally, at -15℃, the stress (with 20% elongation) under MD and TD is above 10 MPa and below 40 MPa, indicating excellent rigidity at -15℃.

[0103] On the other hand, as shown in Table 3, in the substrate film of Comparative Example 1, the functional layer only contains acrylic elastomer. Therefore, 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 under MD and TD) is less than 0.95, indicating poor uniform elongation. In addition, under MD and TD, the ratio of stress (at 5% elongation) to stress (at 40% elongation) at -15°C is greater than 1.05. Therefore, as mentioned above, it can be seen that the formation of yield point cannot be suppressed at -15°C.

[0104] Furthermore, as shown in Table 3, in the substrate film of Comparative Example 2, the functional layer only contains ionomers. Therefore, under MD and TD conditions, the ratio of stress (at 40% elongation) to stress (at 20% elongation) at room temperature (i.e., the elongation of the substrate film under MD and TD) is less than 0.95, indicating poor uniform elongation. Additionally, under TD conditions, the ratio of stress (at 40% elongation) to stress (at 20% elongation) at -15°C (i.e., the elongation of the substrate film under TD) is less than 0.95, indicating poor uniform elongation.

[0105] In addition, as shown in Table 3, in the substrate films of Comparative Examples 3 to 4, the functional layer contains only homopolymer of 1-butene and propylene-based elastomer. Therefore, at room temperature, the stress relaxation rate under MD and TD is less than 25%, indicating poor stress relaxation at room temperature.

[0106] Furthermore, as shown in Table 3, in the substrate film of Comparative Example 5, the content of acrylic elastomer is greater than 50% by mass relative to the functional layer as a whole. Therefore, at room temperature, the stress under TD (with 20% elongation) is less than 5.0 MPa, indicating poor rigidity at room temperature. Additionally, at -15°C, the stress under TD (with 20% elongation) is less than 10 MPa, indicating poor rigidity at -15°C. Furthermore, at room temperature, the stress relaxation rate under TD is less than 25%, indicating poor stress relaxation at room temperature.

[0107] Furthermore, as shown in Table 3, in the substrate film of Comparative Example 6, the functional layer only contains homopolymers and ionomers of 1-butene, resulting in high rigidity and reduced flexibility. Under the TD (40% elongation at -15°C) test of the substrate film, the film fractured. Therefore, it can be seen that the substrate film of Comparative Example 6 cannot suppress the formation of the yield point at -15°C, exhibiting poor uniform elongation. Additionally, at room temperature, the stress relaxation rates under MD and TD are less than 25%, indicating poor stress relaxation at room temperature.

[0108] Industrial availability As explained above, the present invention is suitable for substrate films used in semiconductor manufacturing.

[0109] Explanation of reference numerals in the attached figures 1. Substrate film 2. Functional Layer 3 Surface layer

Claims

1. A substrate film for semiconductor manufacturing, characterized in that, It must have at least a functional layer. The functional layer comprises ionomers and olefin-based elastomers. The content of the ionomer, relative to the entire functional layer, is 10% by mass or more and 80% by mass or less. The content of the olefin-based elastomer is 5% by mass or more and 50% by mass or less relative to the entire functional layer.

2. The substrate film for semiconductor manufacturing according to claim 1, characterized in that, The functional layer comprises a homopolymer of 1-butene. The content of the homopolymer of 1-butene is greater than 0% by mass and less than 80% by mass relative to the entire functional layer.

3. The substrate film for semiconductor manufacturing according to claim 1, characterized in that, The olefin-based elastomer is a propylene-based elastomer.

4. The substrate film for semiconductor manufacturing according to any one of claims 1 to 3, characterized in that, The substrate film for semiconductor manufacturing has a surface layer disposed on at least one side of the functional layer.

5. The substrate film for semiconductor manufacturing according to claim 4, characterized in that, The surface layer contains low-density polyethylene with a density of less than 0.930 g / cm³. The content of low-density polyethylene is 70% by mass or more and 100% by mass or less relative to the total surface layer.

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