Substrate film for semiconductor manufacturing tape

Abstract

A substrate film (1) for semiconductor manufacturing tape comprises at least a functional layer (2). The functional layer (2) contains polybutene, an ionomer, and an olefin-based elastomer. The polybutene content relative to the entire functional layer (2) is 10-80 mass%, the ionomer content relative to the entire functional layer (2) is 10-80 mass%, and the olefin-based elastomer content relative to the entire functional layer (2) is 5-50 mass%.

Description

Substrate film for semiconductor manufacturing tapes

[0001] This invention relates to a base film for semiconductor manufacturing tapes (hereinafter sometimes simply referred to as "base film").

[0002] As a method for manufacturing semiconductor devices such as IC chips, a widely used method involves dividing a wafer circuit, which is formed on a roughly disc-shaped semiconductor wafer, into individual semiconductor devices by dicing on a semiconductor manufacturing tape (dicing tape) for wafers. After dicing, for example, the dicing tape is stretched to create gaps between the semiconductor devices (i.e., expanded), and then each semiconductor device is picked up by a robot or the like.

[0003] Furthermore, a dicing die attach film (DDAF), which has an adhesive layer laminated on the adhesive layer of the dicing tape mentioned above, 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 a gap between semiconductor devices. Then, the adhesive layer is photocured, and the semiconductor devices are peeled off from the adhesive layer and picked up with the adhesive layer attached.

[0004] Furthermore, in recent years, there has been a shift towards stealth dicing (registered trademark) using laser processing equipment that can suppress processing waste and narrow the cut width, and the demand for base films suitable for this dicing method is increasing. More specifically, in stealth dicing (registered trademark), IC chips are divided by expansion under low temperature conditions (for example, -15°C), so there is a particular need for base films that can be uniformly stretched at low temperatures.

[0005] Furthermore, if slack remains in the substrate film after expansion, problems may arise such as the inability to properly house semiconductor devices in racks or the occurrence of defects due to collisions between semiconductor devices. To solve these problems, heat shrink technology exists. This technology involves heating the slack portion of the substrate film to shrink that portion and eliminate the slack. For this to be realized, the substrate film must have excellent heat shrinkability.

[0006] Furthermore, as a base film suitable for the above-mentioned stealth dicing (registered trademark), for example, a base film has been proposed in which a surface layer / intermediate layer / back layer is laminated in that order, with the surface layer and back layer consisting of a resin composition containing polyethylene resin, and the intermediate layer consisting of a resin composition containing thermoplastic polyurethane resin (TPU) (see, for example, Patent Document 1).

[0007] Patent No. 7421339

[0008] However, while the base film described in Patent Document 1 above possesses uniform elongation at low temperatures and heat shrinkage to eliminate sagging, its rigidity is insufficient. This presents a problem in the manufacturing process of the base film, where it is difficult to unwind the base material and form it into tape, including the application of adhesive.

[0009] Therefore, the present invention has been made in view of the above problems, and aims to provide a substrate film for semiconductor manufacturing tapes that is excellent in thermal shrinkability, rigidity, and stress relaxation, as well as excellent in uniform elongation at room temperature and low temperature.

[0010] To achieve the above objective, the semiconductor manufacturing tape substrate film of the present invention is a semiconductor manufacturing tape substrate film having at least a functional layer, wherein the functional layer comprises polybutene, an ionomer, and an olefin-based elastomer, characterized in that the content of polybutene in the functional layer is 10% by mass or more and 80% by mass or less, the content of the ionomer in the functional layer is 10% by mass or more and 80% by mass or less, and the content of the olefin-based elastomer in the functional layer is 5% by mass or more and 50% by mass or less.

[0011] According to the present invention, it is possible to provide a substrate film for semiconductor manufacturing tapes that is excellent in thermal shrinkability, rigidity, and stress relaxation, as well as excellent in uniform elongation at room temperature and low temperature.

[0012] This is a cross-sectional view showing a substrate film for semiconductor manufacturing tape according to an embodiment of the present invention. This is the S-S curve (stress-strain curve) of the substrate film of Example 3 at room temperature. This is the S-S curve (stress-strain curve) of the substrate film of Example 3 at -15°C. This is the S-S curve (stress-strain curve) of the substrate film of Comparative Example 3 at -15°C.

[0013] The semiconductor manufacturing tape substrate film of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be modified and applied as appropriate without altering the essence of the invention.

[0014] The base film of the present invention is a base film composed of a laminate of a functional layer (intermediate layer) and a surface layer provided on at least one side of the functional layer.

[0015] As an example of a base film having this multilayer structure, as shown in Figure 1, a base film 1 is made up of a laminate of a functional layer 2 and surface layers 3 laminated on both sides of the functional layer 2, and has a three-layer structure in which the layers are laminated in the order of surface layer / functional layer / surface layer.

[0016] (Functional layer) Examples of functional layers include those containing polybutene, ionomer, and olefin-based elastomer.

[0017] <Polybutene> In the base film 1 of the present invention, the functional layer 2 contains polybutene in order to improve uniform stretchability and isotropic heat shrinkage.

[0018] More specifically, polybutene has a high molecular weight and bulky side chains, and due to the strong intermolecular forces caused by these bulky side chains, it can improve the uniform stretchability of the substrate film, similar to the case of amorphous polymers, despite being a crystalline polymer.

[0019] Furthermore, due to the above-described structure, when the base film is heated, the film shrinks sufficiently in the direction of the mechanical axis (longitudinal) of the base film (hereinafter referred to as "MD") and in the direction perpendicular thereto (hereinafter referred to as "TD"). As a result, the film shrinks uniformly in both the MD and TD directions, improving the isotropic thermal shrinkage of the base film. Consequently, it becomes possible to eliminate sagging of the film after expansion, thereby avoiding collisions between semiconductor devices and improving the yield (yield of semiconductor devices).

[0020] Examples of polybutene include homopolymers of 1-butene and copolymers of 1-butene and olefins (ethylene, propylene, butadiene, etc.). In the functional layer 2 of the base film 1 of the present invention, it is preferable that the polybutene contains a homopolymer obtained by polymerizing 1-butene alone.

[0021] Furthermore, the polybutene used in this invention may have a weight-average molecular weight (Mw) of approximately 500,000 to 1,500,000.

[0022] The "weight-average molecular weight" mentioned above refers to the value calculated in accordance with JIS K 7252-1:2016.

[0023] Furthermore, because the polybutene used in this invention has a high molecular weight, it has low surface tackiness and higher rigidity compared to amorphous polyolefins. Therefore, in the manufacturing process of the base film, it is possible to provide a base film with high rigidity that allows for tape formation, including unwinding the base and coating with adhesive.

[0024] Based on the above, by using polybutene as the resin for forming the base film, it is possible to simultaneously improve the uniform elongation, isotropic thermal shrinkage, and rigidity of the base film.

[0025] Incidentally, from the viewpoint of improving the uniform stretchability and isotropic heat shrinkability, the content of polybutene in the entire functional layer 2 is 10% by mass or more and 80% by mass or less out of 100% by mass of the functional layer. When the content of polybutene in the entire functional layer 2 is less than 10% by mass, the content of polybutene contributing to the heat shrinkability decreases, so the isotropic heat shrinkability decreases. When the content of polybutene in the entire functional layer 2 is greater than 80% by mass, the content of ionomer contributing to the uniform stretchability at low temperatures, which will be described later, decreases, so the uniform stretchability at low temperatures decreases.

[0026] Incidentally, the content of polybutene in the entire functional layer 2 is preferably 20% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.

[0027] Here, the "low temperature" refers to -15°C ± 2°C (temperature of -17 to -13°C).

[0028] <Ionomer> In the base film 1 of the present invention, from the viewpoint of improving the uniform stretchability at low temperatures and improving the stress relaxation property that enables the dimensional retention of the semiconductor manufacturing tape after expansion, the functional layer 2 contains an ionomer.

[0029] Further, the ionomer in the present invention refers to a synthetic resin in which polymers are aggregated using the cohesive force of metal ions. Specifically, it refers to a resin obtained by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with metal ions, or a resin obtained by crosslinking a terpolymer of ethylene, (meth)acrylic acid, and (meth)acrylate with metal ions.

[0030] Here, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0031] As the above-mentioned metal ions, for example, sodium ion (Na ＋ ), zinc ion (Zn ２＋ ), potassium ion (K ＋ ), lithium ion (Li ＋ ), magnesium ion (Mg２＋ Examples include etc. Further, the neutralization degree of the metal ions in the ionomer is preferably 40 to 75 mol%.

[0032] Further, examples of the above-mentioned (meth)acrylate 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, 2-ethylhexyl (meth)acrylate, and the like.

[0033] Further, the ionomer may be used alone or in combination of two or more.

[0034] Further, as the ionomer, for example, commercially available products such as Himilan (registered trademark) 1605 (a resin obtained by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with Na ions) and Himilan (registered trademark) 1855 (a resin obtained by crosslinking a terpolymer of ethylene, (meth)acrylic acid, and (meth)acrylate ester with Zn ions) can be used.

[0035] And such an ionomer has a side chain of carboxylic acid groups on the molecular chain of polyethylene, and a part of the carboxylic acid groups has a characteristic structure crosslinked between molecular chains by the above-mentioned metal ions. Therefore, the uniform elongation property of the base film at low temperature (-15°C) can be improved. Further, the above-mentioned structure also contributes to the improvement of stress relaxation property, and it becomes possible to hold the semiconductor manufacturing tape by grip ring and to maintain the interval between each semiconductor device (semiconductor chip).

[0036] Further, from the viewpoint of improving stress relaxation property and isotropic thermal shrinkage property, the content of the ionomer in the whole functional layer 2 is 10 mass% or more and 80 mass% or less based on 100 mass% of the functional layer. When the content of the ionomer is less than 10 mass%, the content of the ionomer contributing to stress relaxation property decreases, so the stress relaxation property decreases. When it is more than 80 mass%, the content of polybutene contributing to the above-mentioned thermal shrinkage property decreases, and the isotropic thermal shrinkage property decreases.

[0037] Furthermore, the ionomer content relative to the entire functional layer 2 is preferably 10% to 60% by mass, more preferably 20% to 60% by mass, and even more preferably 20% to 40% by mass, based on 100% by mass of the functional layer.

[0038] Furthermore, "room temperature" as used here refers to a temperature of 23°C ± 2°C (21°C to 25°C).

[0039] Furthermore, from the viewpoint of improving the processing stability of the base film, the melt mass flow rate (MFR) of the ionomer is preferably 0.5 to 5.0 g / 10 min.

[0040] The melt mass flow rate mentioned above is obtained by measurement in accordance with the provisions of JIS K7210:1999.

[0041] Furthermore, from the viewpoint of improving heat resistance, it is preferable that the melting point of the ionomer be 85°C or higher.

[0042] <Olefin-based elastomer> Furthermore, 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 elastomer in JIS K 6200. More specifically, materials composed of amorphous or low-crystallinity α-olefin copolymers are classified as olefin-based elastomers, with polyethylene being the main component and polypropylene being the main component and propylene being the main component. For example, an ethylene-based elastomer is the product name "Toughmer (registered trademark)" manufactured by Mitsui Chemicals, Inc., and an propylene-based elastomer is the product name "Vistamax (registered trademark)" manufactured by ExxonMobil Corporation.

[0043] Furthermore, by using such olefin-based elastomers, the degree of crystallinity is reduced, and the occurrence of yield points in all directions of the base film can be suppressed, thereby improving the uniform elongation of the base film.

[0044] Furthermore, from the viewpoint of improving uniform stretchability, the content of olefin-based elastomer in the functional layer 2 is 5% by mass or more and 50% by mass or less of 100% by mass of the functional layer. If the content of olefin-based elastomer is less than 5% by mass, there will be insufficient olefin-based elastomer components with a low degree of crystallinity, resulting in increased rigidity and decreased flexibility, which may cause the film to break during expansion. Also, if the content of olefin-based elastomer is more than 50% by mass, there will be an excess of olefin-based elastomer components with a low degree of crystallinity, resulting in decreased rigidity, which may make it difficult to unwind the substrate and tape-form including adhesive coating, as well as decreased stress relaxation properties and decreased isotropic thermal shrinkage properties.

[0045] Furthermore, the content of olefin-based elastomer in the functional layer 2 is preferably 10% to 40% by mass, more preferably 10% to 30% by mass, and even more preferably 20% to 30% by mass, based on 100% by mass of the functional layer.

[0046] Furthermore, when using a propylene-based elastomer, from the viewpoint of improving flexibility, the polyethylene content relative to the total propylene-based elastomer is preferably 9% by mass or more and 30% by mass or less of 100% by mass of the propylene-based elastomer.

[0047] Furthermore, from the viewpoint of further improving uniform stretchability, the density of the olefin-based elastomer is 0.850 to 0.900 g / cm³. ３ Preferably, it is 0.860 to 0.890 g / cm³. ３ It is preferable that it be so.

[0048] (Surface Layer) Next, the surface layer 3 of the base film 1 of the present invention will be described. Examples of the surface layer 3 include those containing polyolefin resins such as polyethylene and polypropylene.

[0049] Here, the polyolefin resin refers to a homopolymer (homopolymer) or copolymer (copolymer) of olefins such as ethylene, propylene, and 1-butene, a copolymer of monomers such as vinyl acetate, (meth)acrylic acid, and (meth)acrylate and olefins, and a copolymer obtained by modifying the above monomers with metal ions or acids.

[0050] For example, polypropylene includes homopolymers and copolymers of propylene. Among these, the homopolymer of propylene is a homopolypropylene obtained by polymerizing propylene alone. This homopolymer of polypropylene has high stereoregularity and a large crystallinity contributing to the melting point, so it has excellent heat resistance. Also, due to its large crystallinity, it has high rigidity, but by mixing it with linear low-density polyethylene, flexibility contributing to the expandability of the base film can be obtained.

[0051] <Low-density polyethylene> The surface layer 3 preferably contains low-density polyethylene (LDPE) among polyolefin resins, which has a density of 0.930 g / cm ３ or less. When the density is 0.930 g / cm ３ or less, excessive increase in crystallinity is suppressed and flexibility is improved, so the isotropy of the base film can be improved. When the density is greater than 0.930 g / cm ３ there is a case where the crystallinity increases excessively, so the isotropy may decrease, and also, since the rigidity becomes too large, the pick-up property of the semiconductor device may decrease and the semiconductor device may be damaged.

[0052] Also, from the viewpoint of improving processing stability, the density of low-density polyethylene is preferably 0.860 g / cm ３ or more, and more preferably 0.880 g / cm ３ or more.

[0053] That is, the density is 0.860 g / cm ３ or more and 0.930 g / cm ３The low-density polyethylene described below has low surface tackiness, so when used in the surface layer, it can suppress adhesion to the transport rolls when transporting the base film, and can also suppress blocking when winding the base film, thereby improving the processing stability of the base film.

[0054] Furthermore, among low-density polyethylenes, linear low-density polyethylene (LLDPE) has side-chain branching in the linear structure of high-density polyethylene. Compared to high-density polyethylene, it does not have an excessively high degree of crystallinity and exhibits superior flexibility.

[0055] Furthermore, for strength reasons, linear low-density polyethylene produced using a metallocene catalyst or a Tigler catalyst may be used.

[0056] Furthermore, the melt mass 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 mass flow rate (MFR) is 0.5 g / 10 min or higher, the molecular weight is not too high, which improves flexibility and processability, and when it is 7.5 g / 10 min or lower, the molecular weight is not too low, which improves processing stability.

[0057] The melt mass flow rate mentioned above is obtained by measurement in accordance with the provisions of JIS K7210:1999.

[0058] Based on the above, the resin used to form the base film has a density of 0.93 g / cm³. ３ By using low-density polyethylene as described below, the flexibility and isotropy of the base film can be improved.

[0059] Furthermore, from the viewpoint of suppressing surface tackiness, it is preferable that the content of low-density polyethylene in the 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 of the total surface layer mass.

[0060] Furthermore, 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 ionomer content 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% by mass and 30% by mass or less of 100% by mass of the surface layer.

[0061] Furthermore, the surface layer 3 of the base film 1 of the present invention may contain polybutene such as the homopolymer of 1-butene described above. Despite its high molecular weight, polybutene can be molded using a general-purpose extruder, and because of its high molecular weight component, it has low surface tackiness. When used in the surface layer, it can suppress adhesion to the transport roll when transporting the base film, as well as blockage when winding the base film and draw resonance when molding the base film, thereby improving the processing stability of the base film.

[0062] Furthermore, from the viewpoint of suppressing surface tackiness, it is preferable that the polybutene content in the surface layer 3 (i.e., each of the surface layers 3 laminated on both sides of the functional layer 2) be greater than 0% by mass and 30% by mass or less of 100% by mass of the surface layer.

[0063] <Base Film> In the base film 1 of the present invention, the MD and TD stresses (when stretched by 20%) at room temperature are 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 high, which can reduce the pickability of semiconductor devices and cause damage to the semiconductor devices. If the stress is less than 5.0 MPa, the rigidity becomes too low, which can make it difficult to unwind the base film during the manufacturing process and make it into a tape, including the application of adhesive.

[0064] Furthermore, the stresses of MD and TD at low temperatures (-15°C) (when stretched by 20%) 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 can reduce the pickability of semiconductor devices and cause damage to the semiconductor devices. If the stress is less than 10 MPa, the rigidity becomes too low, which can make it difficult to unwind the substrate during the manufacturing process of the substrate film, and may also make it difficult to form the tape, including coating with adhesive.

[0065] In other words, when the MD and TD stresses at room temperature (when stretched by 20%) are 5.0 MPa or more and 20 MPa or less, or when the MD and TD stresses at -15°C (when stretched by 20%) are 10 MPa or more and 40 MPa or less, a substrate film with excellent rigidity that can be tape-formed, including unwinding the substrate and coating it with an adhesive, can be provided in the manufacturing process of the substrate film.

[0066] Furthermore, the "stress" referred to here can be determined by the method described in the later examples.

[0067] Furthermore, with conventional polyolefin-containing base films, necking does not occur when the base film is stretched by 20%, and it can be expanded uniformly. However, necking begins to occur when the base film is stretched by 40%, making uniform expansion difficult.

[0068] Therefore, in the base film 1 of the present invention, from the viewpoint of improving the uniform stretchability of the base film, it is preferable that the ratio of stress (at 40% stretch) to stress (at 20% stretch) at room temperature and -15°C (i.e., the elongation rate of the base film) in MD and TD is 0.95 or more and 2.00 or less. If the elongation rate of the base film is greater than 2.00, it may become difficult to maintain the expandable ring due to excessive stress increase, and if the elongation rate of the base film is less than 0.95, necking may occur, making uniform expansion difficult.

[0069] In other words, if the elongation rate of the base film is between 0.95 and 2.00, necking will not occur, and uniform expansion will be possible.

[0070] Furthermore, it is more preferable that the elongation rate of the base film be 1.00 or more and 1.80 or less, and even more preferable that the elongation rate of the base film be 1.05 or more and 1.70 or less, from the viewpoint of preventing necking and ensuring uniform expansion.

[0071] Furthermore, in the base film 1 of the present invention, from the viewpoint of further improving the uniform stretchability of the base film, it is preferable that the ratio of stress (at 5% stretch) to stress (at 40% stretch) at room temperature and -15°C in the MD and TD is less than 0.90. If the ratio of stress (at 5% stretch) to stress (at 40% stretch) is less than 0.90, the occurrence of the yield point (the yield point between stretching from 0% to 100% under the condition of a tensile speed of 300 mm / min) described later can be suppressed, thereby suppressing necking and enabling uniform expansion.

[0072] Furthermore, it is more preferable that the ratio of stress (at 5% elongation) to stress (at 40% elongation) is 0.35 or more and less than 0.80, and even more preferable that the ratio of stress (at 5% elongation) to stress (at 40% elongation) is 0.35 or more and less than 0.75, from the viewpoint of preventing necking and ensuring uniform expansion.

[0073] Furthermore, in the base film 1 of the present invention, the stress relaxation rate at room temperature is preferably 23% or more, more preferably 25% or more, even more preferably 30% or more, and particularly preferably 35% or more. If the stress relaxation rate is less than 23%, the stress absorption performance is poor, which may make it difficult to maintain the dimensions of the semiconductor manufacturing tape.

[0074] In other words, when the stress relaxation rate is 23% or higher, it becomes possible to maintain the dimensions of the semiconductor manufacturing tape, and a substrate film for semiconductor manufacturing tapes with excellent stress relaxation properties can be provided.

[0075] The "stress relaxation rate" referred to here can be determined by the method described in the examples below.

[0076] Furthermore, in the base film 1 of the present invention, it is preferable that the thermal shrinkage rate when heated at 110°C for 15 minutes is -0.5% or more and 4.5% or less. Note that a thermal shrinkage rate of less than 0% (i.e., a negative value) indicates thermal expansion of the base film.

[0077] If the thermal shrinkage rate is less than -0.5%, the base film will stretch excessively, which may cause misalignment of the semiconductor device and reduce the yield (semiconductor device yield). If the thermal shrinkage rate is greater than 4.5%, the base film will shrink excessively, which may cause misalignment of the semiconductor device and reduce the yield (semiconductor device yield).

[0078] Furthermore, from the viewpoint of suppressing the aforementioned decrease in yield, the thermal shrinkage rate of the base film is preferably greater than 0% and 2.0% or less, and more preferably 0.5% or more and 1.5% or less.

[0079] Furthermore, the aforementioned "thermal shrinkage rate" can be determined by the method described in the examples below.

[0080] Furthermore, in the base film 1 of the present invention, from the viewpoint of improving the isotropic thermal shrinkage of the base film and further suppressing the decrease in semiconductor chip yield, it is preferable that the ratio of the thermal shrinkage rate in MD (thermal shrinkage rate when heated at 110°C for 15 minutes) to the thermal shrinkage rate in TD (thermal shrinkage rate when heated at 110°C for 15 minutes) is between -0.5 and 3.0. If the ratio of the thermal shrinkage rate in MD to the thermal shrinkage rate in TD is less than -0.5, the base film will stretch in either the MD or TD, which increases the anisotropy of the base film and may decrease the yield (yield of semiconductor devices). If the ratio of the thermal shrinkage rate in MD to the thermal shrinkage rate in TD is greater than 3.0, the base film will stretch or shrink excessively in either the MD or TD, which increases the anisotropy of the base film and may decrease the yield (yield of semiconductor devices).

[0081] Furthermore, from the viewpoint of suppressing the aforementioned decrease in yield, the ratio of the thermal shrinkage rate in MD to the thermal shrinkage rate in TD is preferably greater than 0 and 2.0 or less, and more preferably between 0.5 and 1.6 or less.

[0082] The thickness of the base film 1 of the present invention is preferably 50 to 300 μm, and more preferably 80 to 150 μm. If the thickness of the base film is 50 μm or more, handling properties can be improved, and if the thickness is 300 μm or less, flexibility (expandability) can be improved. In the case of a base film for wafers, the thickness of the base film is preferably 50 to 150 μm, and more preferably 70 to 110 μm.

[0083] Furthermore, in the case of a base film having a three-layer structure in which a surface layer / functional layer / surface layer is laminated in that order, the thickness of the surface layer is not particularly limited, but is preferably 2 to 60 μm, and more preferably 4 to 40 μm. Similarly, the thickness of the functional layer is not particularly limited, but is preferably 40 to 120 μm, and more preferably 50 to 80 μm.

[0084] Furthermore, for example, in the case of a base film having a three-layer structure in which a surface layer / functional layer / surface layer is laminated in that order, from the viewpoint of processability and low cost, the ratio of the functional layer to the entire base film is preferably 40 to 95%, and more preferably 50 to 90%.

[0085] <Manufacturing Method> For example, when manufacturing a base film 1 having a three-layer structure in which a surface layer / functional layer / surface layer is laminated in that order, as shown in Figure 1, first, a resin material for forming the surface layer and a resin material for forming the functional layer are prepared.

[0086] Next, using a co-extruder equipped with a T-die for three types of three layers, the resin material for forming the surface layer and the resin material for forming the functional layer are simultaneously extruded and molded at a predetermined temperature to produce a base film 1 having the multilayer structure of the present invention, which is composed of a laminate of a functional layer 2 and a surface layer 3 laminated on both sides of the functional layer 2. Alternatively, the base film of the present invention may be produced by known calendering or inflation methods.

[0087] <Other Embodiments> The base film 1 of the present invention may contain various additives. As additives, known additives commonly used in semiconductor manufacturing tapes can be used, such as crosslinking aids, antistatic agents, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, colorants, crystal nucleating agents, and processing aids. These additives may be used individually or in combination of two or more.

[0088] Furthermore, as an antistatic agent, from the viewpoint of providing semi-permanent antistatic properties, a polymer-type antistatic agent such as a block copolymer of a propylene resin and a polyhydric alcohol, particularly a copolymer of polypropylene and polyethylene glycol, is preferred.

[0089] Furthermore, although a base film having a three-layer structure in which a surface layer / functional layer / surface layer is laminated in that order was used as an example in the explanation, the base film having a multilayer structure of the present invention is not limited to a three-layer structure, as long as the above-mentioned functional layer is provided, and may also be a base film having a five-layer structure in which a surface layer / functional layer / functional layer / functional layer / surface layer is laminated in that order.

[0090] Furthermore, although the above-described embodiment used a base film 1 having a three-layer structure in which a surface layer / functional layer / surface layer is laminated in that order as an example, the base film of the present invention may also be a base film having a single-layer structure consisting only of the functional layer 2 described above.

[0091] In this case, first, a resin material for forming the functional layer is prepared, and then, using a co-extruder for three types of three layers equipped with a T-die, the resin material for forming the functional layer is extruded at a predetermined temperature to form a base film having a single-layer structure consisting only of the functional layer 2. Alternatively, the base film may be manufactured by a known calendering method or inflation method, similar to the embodiment described above.

[0092] 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 and altered in accordance with the spirit of the invention; such modifications do not exclude them from the scope of the invention.

[0093] The materials used to prepare the base film are as follows: (1) LLDPE: Linear low-density polyethylene, melting point: 121°C, density: 0.922 g / cm³ ３ (2) 1-Bu: Homopolymer of 1-butene, melting point: 128°C, density: 0.920 g / cm³ ３ MFR: 0.5 g / 10 min (3) PP elastomer: Propylene-based elastomer, density: 0.862 g / cm³ ３ MFR: 3.0 g / 10 min (230°C), polyethylene content: 16% (manufactured by ExxonMobil, trade name: Vistamax® 6102FL) (4) Ionomer 1: 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 / cm³ ３ MFR: 1.0 g / 10 min (5) Ionomer 2: Binary ionomer, resin obtained by crosslinking a binary copolymer of ethylene and (meth)acrylic acid with Na ions, melting point: 92°C, density: 0.940 g / cm³ ３ MFR: 2.8 g / 10 min (6) TPU elastomer: Polyurethane elastomer, density: 1,200 g / cm³ ３ (Manufactured by BASF Japan, product name: Elastran® C90A) (7) EVA: Ethylene-vinyl acetate copolymer, melting point: 93°C, density: 0.929 g / cm³ ３ MFR: 9.0g / 10min, Vinyl acetate content: 10% (Manufactured by Tosoh Corporation, Product name: Ultrasen 541)

[0094] (Example 1) <Preparation of base 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 having the composition (parts by mass) shown in Table 1. Next, these resin materials were simultaneously extruded using a three-layer co-extruder with a T-die, under conditions of a die temperature of 180 to 230°C and a chill roll temperature of 30°C, to obtain a base film having the thickness shown in Table 1 and a three-layer structure in which the surface layer / functional layer / surface layer was laminated in that order.

[0095] <Evaluation of the presence or absence of yield point> Using the prepared base film, a sample for measurement was obtained in accordance with JIS K7161-2:2014. Next, the obtained sample for measurement was set in a tensile testing machine (Shimadzu Corporation, product name: AG-5000A) with a grip distance of 40 mm, and a tensile test was performed in accordance with JIS K7161-2:2014 at room temperature (23°C) and relative humidity of 40% at a tensile speed of 300 mm / min.

[0096] Similarly, the measurement samples obtained as described above were set in a tensile testing machine (Shimadzu Corporation, product name: AG-5000A) with a grip distance of 40 mm, and a tensile test was performed in accordance with JIS K7161-2:2014 at a temperature of -15°C and a tensile speed of 500 mm / min.

[0097] Then, in the S-S curves (stress-strain curves) of MD and TD at room temperature and -15°C, those in which no yield point was observed between elongation from 0% to 100% (no necking occurred and uniform expansion was reliably possible) were marked with ◎, those in which almost no yield point was observed between elongation from 0% to 100% (necking was suppressed and nearly uniform expansion was possible) were marked with ○, and those in which a yield point was observed between elongation from 0% to 100% (necking occurred and uniform expansion was impossible) were marked with ×. The results are shown in Table 1.

[0098] <Measurement of stress in MD and TD> Using the prepared base film, a sample for measurement was obtained in accordance with JIS K7161-2:2014. Next, the obtained sample for measurement was set in a tensile testing machine (Shimadzu Corporation, product name: AG-5000A) with a grip distance of 40 mm, and a tensile test was performed in accordance with JIS K7161-2:2014 at room temperature (23°C) and relative humidity of 40% at a tensile speed of 300 mm / min.

[0099] Similarly, the measurement samples obtained as described above were set in a tensile testing machine (Shimadzu Corporation, product name: AG-5000A) with a grip distance of 40 mm, and a tensile test was performed in accordance with JIS K7161-2:2014 at a temperature of -15°C and a tensile speed of 500 mm / min.

[0100] The stress (20% stress) of the substrate film at 20% elongation of MD and TD was measured at room temperature and -15°C. The results are shown in Table 1.

[0101] Similarly, the stress (40% stress) of the MD and TD of the base film at 40% elongation was measured at room temperature and -15°C. Furthermore, the ratio of stress (at 40% elongation) to stress (at 20% elongation) in the MD section (i.e., the elongation rate of the base film in the MD section) and the ratio of stress (at 40% elongation) to stress (at 20% elongation) in the TD section (i.e., the elongation rate of the base film in the TD section) were calculated at room temperature and -15°C. The results are shown in Table 1.

[0102] Similarly, the stress (5% stress) of the MD and TD of the base film at 5% elongation was measured at room temperature and -15°C. The ratio of stress (at 5% elongation) to stress (at 40% elongation) for the MD and the ratio of stress (at 5% elongation) to stress (at 40% elongation) for the TD were also calculated at room temperature and -15°C. The results are shown in Table 1.

[0103] <Calculation of Stress Relaxation Rate> Using the prepared base film, a sample for measurement was obtained in the shape of a No. 1 dumbbell (width 10 mm, length 120 mm). Next, the obtained sample for measurement was set in a tensile testing machine (Shimadzu Corporation, product name: AG-5000A) with a grip distance of 80 mm, and the sample was stretched by 25% to MD (or TD) at a tensile speed of 300 mm / min in an environment with a temperature of room temperature (23°C) and a relative humidity of 40%.

[0104] And the stress (initial stress S) when it is stretched by 25%. ０ The stress (relaxed stress S) after 60 seconds is measured, and the elongation of the test specimen is held for 60 seconds. １The following was measured. Then, using the following equation (1), the initial stress S mentioned above was calculated. ０ and relaxed stress S １ From the difference, the stress relaxation rates [%] of the MD and TD of the base film at room temperature were calculated. The results are shown in Table 1.

[0105] [Equation 1] Stress relaxation rate [%] = [(Initial stress S ０ - Relaxed stress S １ ) / Initial stress S ０ ] × 100 (1)

[0106] <Calculation of Heat Shrinkage Rate> A sample of a predetermined size (10 cm x 10 cm) was cut from the prepared stretched film. Orthogonal markings, each 8 cm long and parallel to the edge, were drawn 1 cm inward from each edge of the sample. The sample was placed in an oven at 110°C and heated for 15 minutes. After removal, it was cooled to room temperature (approximately 25°C). The distance between the markings at MD and TD was measured in the heat-treated sample. The heat shrinkage rate [%] was calculated from the change in the distance between the markings at MD and TD before and after heating using the following formula (2), and this was used as an indicator of heat resistance. The results are shown in Table 1.

[0107] [Equation 2] Thermal shrinkage rate [%] in MD (or TD) = [(gauge between gauge marks before heating (8 cm) - gauge between gauge marks after heating) / gauge between gauge marks before heating (8 cm)] × 100 (2)

[0108] Furthermore, the ratio of the thermal shrinkage rate [%] in MD to the thermal shrinkage rate [%] in TD was calculated. The results are shown in Table 1.

[0109] (Examples 2-13, Comparative Examples 1-6) Except for changing the composition of the resin component to the compositions (parts by mass) shown in Tables 1-3, a base film having the thickness shown in Tables 1-3 and a three-layer structure with a surface layer / functional layer / surface layer was obtained in the same manner as in Example 1 described above.

[0110] Then, in the same manner as in Example 1 described above, the presence or absence of the yield point was evaluated, stress was measured in MD and TD, the stress relaxation rate was calculated, and the thermal shrinkage rate was calculated. The results are shown in Tables 1 to 3.

[0111] Figures 2 and 3 show the S-S curves (stress-strain curves at room temperature and -15°C) for MD and TD in the base film of Example 3. As shown in Table 1, for MD and TD, the ratio of stress (at 5% elongation) to stress (at 40% elongation) at room temperature and -15°C is less than 0.90. Therefore, as shown in Figures 2 and 3, the S-S curves (stress-strain curves at room temperature and -15°C) for MD and TD do not show a yield point between elongation from 0% to 100%.

[0112] Furthermore, Figure 4 shows the S-S curves (stress-strain curves at -15°C) for MD and TD in the base film of Comparative Example 3. As shown in Table 3, in TD, the ratio of stress (at 5% elongation) to stress (at 40% elongation) at -15°C is 0.90 or higher. Therefore, as shown in Figure 4, the yield point is found in the S-S curve (stress-strain curve at -15°C) of TD between the elongation rate of 0% and 100%.

[0113]

[0114]

[0115]

[0116] As shown in Tables 1-2, in the base films of Examples 1-13, the functional layer contains a homopolymer of 1-butene, an ionomer, and a propylene-based elastomer, with the content of the homopolymer of 1-butene being 10% to 80% by mass of the total functional layer, the content of the ionomer being 10% to 80% by mass of the total functional layer, and the content of the propylene-based elastomer being 5% to 50% by mass of the total functional layer, the MD and TD are at room temperature and -15 Since the ratio of stress (at 5% elongation) to stress (at 40% elongation) at °C is less than 0.90, the occurrence of the yield point can be suppressed at room temperature and -15°C. Since the ratio of stress (at 40% elongation) to stress (at 20% elongation) at room temperature and -15°C (i.e., the elongation rate of the base film in MD and TD) is between 0.95 and 2.00, necking does not occur at room temperature and -15°C, uniform expansion is possible, and it can be seen that the material has excellent uniform elongation properties. Furthermore, since the stress relaxation rate in MD and TD at room temperature is 23% or more, it can be seen that the material has excellent stress relaxation properties at room temperature. Furthermore, since the stress (at 20% elongation) in MD and TD at room temperature is between 5.0 MPa and 20 MPa, it can be seen that the material has excellent rigidity at room temperature. Furthermore, at -15°C, the stress in MD and TD (when elongated by 20%) is between 10 MPa and 40 MPa, indicating excellent rigidity at -15°C. In addition, the thermal shrinkage rate of MD and TD when heated at 110°C for 15 minutes is between -0.5% and 4.5%, and the ratio of the thermal shrinkage rate of MD (when heated at 110°C for 15 minutes) to the thermal shrinkage rate of TD (when heated at 110°C for 15 minutes) is between -0.5 and 3.0, indicating excellent isotropic thermal shrinkage of the base film, which can suppress a decrease in semiconductor chip yield.

[0117] On the other hand, as shown in Table 3, in the base film of Comparative Example 1, since the functional layer contains only polyurethane elastomer, the stress at MD and TD (when stretched by 20%) is less than 5.0 MPa at room temperature, indicating poor rigidity at room temperature. Furthermore, at -15°C, the stress at MD and TD (when stretched by 20%) is less than 10 MPa, indicating poor rigidity at low temperatures.

[0118] Furthermore, as shown in Table 3, in the base film of Comparative Example 2, the functional layer contains only an ionomer and does not contain a 1-butene homopolymer. As a result, the thermal shrinkage rate in MD when heated at 110°C for 15 minutes is greater than 4.5%, and the ratio of the thermal shrinkage rate in MD (when heated at 110°C for 15 minutes) to the thermal shrinkage rate in TD (when heated at 110°C for 15 minutes) is less than -0.5. Therefore, the base film has poor isotropic thermal shrinkage properties, and it is not possible to suppress the decrease in semiconductor chip yield.

[0119] Furthermore, as shown in Table 3, in the base film of Comparative Example 3, the functional layer contains only 1-butene homopolymer and propylene elastomer, and does not contain ionomer. As a result, the stress relaxation rate in MD and TD at room temperature is less than 23%, indicating poor stress relaxation at room temperature. In addition, because the content of 1-butene homopolymer in the functional layer is greater than 80% by mass, the ratio of stress (at 5% elongation) to stress (at 40% elongation) at -15°C in TD is 0.90, indicating that the occurrence of the yield point cannot be suppressed and that uniform elongation is poor.

[0120] Furthermore, as shown in Table 3, in the base film of Comparative Example 4, since the functional layer does not contain a homopolymer of 1-butene, the thermal shrinkage rate in MD when heated at 110°C for 15 minutes is greater than 4.5%, and the ratio of the thermal shrinkage rate in MD (thermal shrinkage rate when heated at 110°C for 15 minutes) to the thermal shrinkage rate in TD (thermal shrinkage rate when heated at 110°C for 15 minutes) is greater than 3.0. This indicates that the base film has poor isotropic thermal shrinkage properties and cannot suppress the decrease in semiconductor chip yield.

[0121] Furthermore, as shown in Table 3, in the base film of Comparative Example 5, the content of propylene-based elastomer in the functional layer is greater than 50% by mass. As a result, at room temperature, the stress at TD (when stretched by 20%) is less than 5.0 MPa, and at -15°C, the stress at TD (when stretched by 20%) is less than 10 MPa, indicating poor rigidity at both room temperature and -15°C. In addition, at room temperature, the stress relaxation rate at TD is less than 23%, indicating poor stress relaxation at room temperature. Furthermore, the thermal shrinkage rate at MD when heated at 110°C for 15 minutes is greater than 4.5%, and the ratio of the thermal shrinkage rate at MD (when heated at 110°C for 15 minutes) to the thermal shrinkage rate at TD (when heated at 110°C for 15 minutes) is greater than 3.0. This indicates poor isotropic thermal shrinkage of the base film, making it impossible to suppress the decrease in semiconductor chip yield.

[0122] Furthermore, as shown in Table 3, in the base film of Comparative Example 6, the functional layer contains only a homopolymer of 1-butene and an ionomer, and does not contain a propylene-based elastomer. As a result, it has high rigidity and low flexibility, and the film broke at the TD (40% elongation at -15°C). Therefore, it can be seen that the base film of Comparative Example 6 was unable to suppress the occurrence of the yield point at -15°C and had poor uniform elongation.

[0123] As described above, the present invention is suitable for substrate films for semiconductor manufacturing tapes.

[0124] 1. Base film 2. Functional layer 3. Surface layer

Claims

1. A substrate film for semiconductor manufacturing tapes having at least a functional layer, wherein the functional layer comprises polybutene, an ionomer, and an olefin-based elastomer, the polybutene content of the functional layer is 10% by mass or more and 80% by mass or less, the ionomer content of the functional layer is 10% by mass or more and 80% by mass or less, and the olefin-based elastomer content of the functional layer is 5% by mass or more and 50% by mass or less.

2. The semiconductor manufacturing tape substrate film according to claim 1, characterized in that the polybutene is a homopolymer of 1-butene.

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

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

5. The surface layer has a density of 0.930 g / cm³. ３ The semiconductor manufacturing tape base film according to claim 4, comprising the following low-density polyethylene, wherein the content of the low-density polyethylene relative to the entire surface layer is 70% by mass or more and 100% by mass or less.

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