Polyolefin film, semiconductor manufacturing process film, semiconductor chip manufacturing method, and manufacturing device

Abstract

To provide a polyolefin film which has excellent stretchability of the film on an upper surface portion of a stage of an expanding device, that is, has sufficiently high extensibility of a chip interval on the upper surface portion of the stage of the expanding device, and further has excellent cuttability.SOLUTION: A polyolefin film has an A layer that satisfies (i) and (ii) on at least one side, and has a tensile elongation at break of 250% or more. (i) In a load removal test in nanoindentation, the surface indentation hardness is 40 MPa or more and 150 MPa or less. (ii) The sum of a projecting peak height Spk and a projecting valley depth Svk, Spk + Svk, is 0.5 μm or more and 3.0 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyolefin film. [Background technology]

[0002] In the semiconductor chip manufacturing process, a semiconductor wafer such as a silicon wafer, sapphire wafer, or SiC wafer is diced (cut) into chips, then expanded (stretched) to widen the gap between the chips, and the individual chips are then picked up. A dicing film is used to secure the semiconductor wafer (hereinafter sometimes simply referred to as wafer) in place during the dicing and expanding processes.

[0003] Dicing film consists of an adhesive layer for attaching the wafer and a base film that supports it. In the dicing and expanding processes, the wafer attached to the adhesive surface of the dicing film is diced into chips, and then the dicing film is pushed up on a circular stage from the side of the dicing film opposite the chip-attached side (hereinafter sometimes referred to as the back side), stretching the film on the upper surface of the stage in all directions and widening the gap between the chips.

[0004] Until now, vinyl chloride resin (PVC), which has excellent stretchability, has been used as the base film for this application. However, PVC has environmental issues, such as the inclusion of regulated substances such as dioctyl phthalate as a plasticizer, and its flame retardancy resulting in large CO2 emissions during disposal. As a result, dicing films using olefin-based resins as the base film have been proposed as an alternative material (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-9018 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-109808 [Patent Document 3] Patent Publication No. 2021-106187 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 proposes a substrate film for dicing films, which is made by adding a component such as a copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative resin thereof to a polyolefin resin. However, due to the flexibility of the material, the film's cuttability is insufficient when used in the dicing process. Furthermore, there are concerns that the backside of the film may adhere to the top surface or corners of the expansion stage during expansion, resulting in insufficient slipperiness, resulting in insufficient stretchability of the film in the center of the stage's top surface, which may cause problems when picking up semiconductor chips. Patent Document 2 also proposes a dicing tape with a slip-resistant layer, but the substrate film is flexible, raising concerns about poor cuttability. Furthermore, in recent years, semiconductor chips have become increasingly miniaturized, and there is a demand for improved pickup speed. In order to pick up semiconductor chips with high precision even in such cases, sufficient chip spacing is required, especially in the center of the stage's top surface. However, Patent Document 2 raises concerns about insufficient film stretchability and insufficient pickup ability. Patent Document 3 proposes the use of slippery particles, but although this provides excellent uniformity in the circumferential direction of expansion, there is a concern that the stretchability of the film on the upper surface of the stage may be insufficient, causing problems with picking up semiconductor chips.

[0007] The present invention aims to provide a polyolefin film that, when used as a dicing film, has excellent stretchability of the film on the upper surface of the stage of an expanding device, i.e., has sufficiently high expandability of the chip spacing on the upper surface of the stage of an expanding device, and also has excellent cutting properties. [Means for solving the problem]

[0008] The preferred embodiments of the present invention are as follows. (1) A polyolefin film having a layer A that satisfies (i) and (ii) on at least one side and having a tensile elongation at break of 250% or more. (i) In a loading / unloading test using nanoindentation, the surface indentation hardness is 40 MPa or more and 150 MPa or less. (ii) The sum of the protruding peak height Spk and the protruding valley depth Svk, Spk+Svk, is 0.5 μm or more and 3.0 μm or less. (2) The polyolefin film according to (1), having a storage modulus E'(-20) at -20°C of 1.8 GPa or more and a storage modulus E'(50) at 50°C of 0.3 GPa or less. (3) A polyolefin film according to (1) or (2), in which P2 / P1 is 1.0 or more and 3.0 or less, where P1 (MPa) is the tensile stress at an elongation of 10% and P2 (MPa) is the tensile stress at an elongation of 200%. (4) The polyolefin film according to any one of (1) to (3), which has a haze of 7% or more and 55% or less. (5) The polyolefin film according to any one of (1) to (4), having a surface haze of 5% or more and 38% or less. (6) The polyolefin film according to any one of (1) to (5), characterized in that, when the entirety of Layer A is taken as 100% by mass, Layer A contains a polypropylene resin as a main component and 10% by mass to 40% by mass of a polyethylene resin having a melting point of 125°C or higher, and the melt viscosity of the polyethylene resin is 300 Pa·s to 850 Pa·s higher than the melt viscosity of the polypropylene resin. -1 The value is measured using a capillary flow tester under the conditions above. (7) The polyolefin film according to any one of (1) to (6), wherein the coefficient of static friction between the surfaces of the layer A is 0.1 or more and 0.6 or less. (8) The polyolefin film according to any one of (1) to (7), which is used for wafer dicing or wafer expanding. (9) A film for semiconductor manufacturing processes, comprising the polyolefin film according to any one of (1) to (8). (10) A method for manufacturing a semiconductor chip using the semiconductor manufacturing process film according to (9). (11) A manufacturing apparatus for manufacturing semiconductor chips using the semiconductor manufacturing process film according to (9). [Effects of the Invention]

[0009] According to the present invention, a polyolefin film can be provided that, when used as a dicing film, has excellent stretchability of the film on the upper surface of the stage of an expanding device, i.e., has sufficiently high expandability of the chip spacing on the upper surface of the stage of an expanding device, and also has excellent cutting properties. [Brief explanation of the drawings]

[0010] [Figure 1] Schematic diagram showing the measurement method of the expand test. [Figure 2] FIG. 10 is a schematic diagram showing a method for evaluating the chip-to-chip distance. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described.

[0012] A preferred embodiment of the present invention is a polyolefin film having, on at least one surface thereof, a layer A that satisfies the following (i) and (ii), and having a tensile elongation at break of 250% or more. (i) In a loading / unloading test using nanoindentation, the indentation hardness of at least one surface is 20 MPa or more and 60 MPa or less. (ii) The sum of the protruding peak height Spk and the protruding valley depth Svk, Spk+Svk, is 0.5 μm or more and 3.0 μm or less.

[0013] <Polyolefin film> From an environmental perspective, the polyolefin film of the present invention preferably contains at least 50% by mass of a polyolefin resin in at least one layer constituting the film, assuming the total mass of the layer to be 100% by mass. The polyolefin resin in the present invention is preferably one or more selected from polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and low-crystalline or amorphous ethylene-α-olefin copolymers; polypropylene resins such as homopolypropylene, random copolymers of propylene with ethylene and / or butene-1, block polypropylene, propylene-α-olefin copolymers, and propylene-ethylene-α-olefin copolymers; polybutene resins such as polybutene-1, polybutene-1-ene copolymers, and polybutene-1-propylene copolymers; 4-methyl-1-pentene-α-olefin copolymers; ethylene-ethyl (meth)acrylate copolymers; ethylene-methyl (meth)acrylate copolymers; ethylene-n-butyl (meth)acrylate copolymers; and ethylene-vinyl acetate copolymers. Examples of the α-olefin include propylene, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0014] Furthermore, the polyolefin film of the present invention preferably has an A layer that satisfies the above (i) and (ii) on at least one side, but may be a film consisting of one layer (i.e., a single layer consisting of only A layer) or a film consisting of two or more layers. When consisting of multiple layers, these multiple layers may be the same or different from each other. That is, all layers may be the same, all layers may be different, or only some layers may be the same. When the multiple layers are different from each other, the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. Here, ``multiple layers are different from each other'' means that at least one of the material and average thickness of each layer is different from each other.

[0015] <Tensile elongation at break> The polyolefin film of the present invention preferably has a tensile breaking elongation of 250% or more. Tensile tests are performed five times in each of the machine direction (MD) and transverse direction (TD) of the polyolefin film at 23°C and 300 mm / min, using the method described in the Examples, and the arithmetic mean value of the tensile breaking elongation (arithmetic mean value of a total of 10 points) is taken as the tensile breaking elongation of the polyolefin film. If the MD and TD of the polyolefin film are unknown, the tensile breaking elongation is calculated using the following method. First, starting from any direction in the film plane, tensile tests are performed five times in six directions at 30° intervals. The arithmetic mean value of the tensile breaking elongation in each direction is then calculated, and the arithmetic mean value (average of a total of 10 tests) of the direction with the highest tensile breaking elongation and the direction 90° to that direction is taken as the tensile breaking elongation of the polyolefin film. In each evaluation of the polyolefin film of the present invention described later, evaluation of both MD and TD is required, and when MD and TD are unknown, the values evaluated in the direction with the highest tensile elongation at break and in the direction at 90° to this direction are used.

[0016] By having a tensile breaking elongation of 250% or more, when the polyolefin film of the present invention is used for wafer dicing or wafer expanding, it can be used well without film breakage when expanding chips or lifting up and picking up chips. From the same viewpoint, the tensile breaking elongation is more preferably 400% or more, and even more preferably 600% or more. There is no particular upper limit to the tensile breaking elongation, but it is substantially about 1,500% or less.

[0017] From the viewpoint of controlling the tensile elongation at break to 400% or more, it is preferable to use a suitable resin for each of the materials constituting the substrate layer, Layer A, Layer B, and Layer C described below. Also, from the viewpoint of controlling the tensile elongation at break to 400% or more, the polyolefin film of the present invention is preferably produced by melt extrusion using a T-die method, and more preferably does not include a heat stretching step such as sequential biaxial stretching or simultaneous biaxial stretching.

[0018] <Indentation hardness> The polyolefin film of the present invention has Layer A, whose surface indentation hardness is 40 MPa or more and 150 MPa or less in a nanoindentation load-unload test. The indentation hardness is measured by the method described in the Examples.

[0019] In wafer expanding applications, which are one of the preferred applications of the polyolefin film of the present invention, as mentioned above, a method is generally used in which a circular stage is pushed up from the back side of the dicing film to stretch the film on the stage in all directions and widen the chip spacing. In this case, if the back surface of the dicing film has low slipperiness, friction will occur between the upper surface of the circular stage and the back surface of the film, and particularly large friction will occur between the corners around the stage and the back surface of the film, which will inhibit the stretching of the film on the top surface of the stage and may prevent the chip spacing from being sufficiently widened.

[0020] The polyolefin film of the present invention has an indentation hardness of 40 MPa or more on the surface of Layer A, which prevents the back surface of the film (the surface of Layer A) from adhering too closely to the upper surface or corners of the stage when the stage is pushed up, thereby exhibiting good slip properties. This improves the stretchability of the film on the upper surface of the stage, making it possible to sufficiently widen the chip spacing. Furthermore, an indentation hardness of 40 MPa or more on the surface of Layer A improves the film's manufacturing process, processing process, and cuttability during use. The indentation hardness of the polyolefin film of the present invention is preferably 150 MPa or less, from the viewpoint of ensuring slip properties while maintaining appropriate flexibility and making the film easy to stretch.

[0021] From the same viewpoint as above, the indentation hardness is more preferably 60 MPa or more, and more preferably 120 MPa or less. One method for controlling the indentation hardness of the present invention is to control the material constituting layer A, and details will be described later.

[0022] <Spk+Svk> As mentioned above, during the semiconductor wafer (chip) expanding process, friction occurs between the top surface and corners of the stage and the back surface of the dicing film. Particularly near the corners of the stage, the film is likely to be pressed firmly against the stage due to the stage's upward thrust. If the height of the convex structure on the back surface of the film is too large, localized friction increases, potentially impairing slippage. Furthermore, if the depth of the concave structure on the back surface of the film is too small, the contact area between the stage and the back surface of the film increases, potentially impairing slippage.

[0023] In the present invention, in addition to controlling the indentation hardness as described above, we have found that by configuring the surface structure of layer A of the polyolefin film so that Spk + Svk, the sum of the protruding peak height Spk and the protruding valley depth Svk, is 0.5 μm or more, the contact area between the stage and the back surface of the film is suppressed, the slipperiness is improved, and the film on the top surface of the stage can be sufficiently stretched. Furthermore, we have found that by setting Spk + Svk to 3.0 μm or less, local friction between the corner of the stage and the back surface of the film can be suppressed, thereby preventing the film on the side of the stage from stretching alone and allowing the film to be sufficiently stretched up to the center of the top surface of the stage.

[0024] Spk and Svk are measured in accordance with ISO25178-2 (2012) by the method described in the Examples. Spk+Svk is preferably 1.0 μm or more in terms of reducing friction on the surface of Layer A. Another effect of controlling Spk+Svk to 3.0 μm or less is that when an adhesive layer is provided on the surface opposite at least one of Layer A of the polyolefin film of the present invention and the film is wound into a roll, the surface shape of Layer A is prevented from being transferred to the adhesive layer, thereby suppressing a decrease in adhesive strength. From the viewpoints of suppressing such a decrease in adhesive strength and reducing the friction on the surface of Layer A, Spk+Svk is more preferably 2.5 μm or less, and even more preferably 2.0 μm or less.

[0025] In addition, in the polyolefin film of the present invention, from the viewpoint of reducing friction on the surface of Layer A during the expanding process and improving the stretchability of the film on the stage surface, it is preferable that the ratio of Svk to Spk, Svk / Spk, is 0.3 or more.

[0026] Spk+Svk and Svk / Spk can be controlled by adjusting the materials constituting the layer A of the polyolefin film of the present invention and the production conditions, as will be described in more detail below.

[0027] <E’(-20)> The polyolefin film of the present invention preferably has a storage modulus E'(-20) of 1.2 GPa or more at -20°C under an amplitude strain of 0.05% and 10 Hz. Here, the storage modulus E' refers to a value measured by DMA (dynamic mechanical analysis), and the measurement method is the method described in the Examples. By setting E'(-20) to 1.2 GPa or more, it is possible to ensure high stretchability of the polyolefin film of the present invention while providing good control over cutting the film. From the same viewpoint, E'(-20) is more preferably 1.5 GPa or more, and even more preferably 1.8 GPa or more. Furthermore, E'(-20) is preferably 3.0 GPa or less from the viewpoint of well controlling the balance between stretchability and cuttability when the polyolefin film of the present invention is used for expandable applications.

[0028] In the wafer expanding process, the film is expanded (stretched) by pushing up the circular stage of the expanding device as described above. In this case, the film on the top surface of the circular stage and the film positioned on the side after being pushed up have different stretching modes (stretching strain rates). Therefore, in the present invention, the inventors focused on the time-temperature conversion law of the viscoelasticity of the film, and found that by controlling the above-mentioned E'(-20) and the later-described E'(50), the polyolefin film of the present invention exhibits superior expandability and processability.

[0029] One method for controlling the storage modulus E'(-20) of the polyolefin film of the present invention to 1.2 GPa or more is to have the polyolefin film of the present invention contain a resin with a high storage modulus at -20°C. It is preferable to use one or more polypropylene resins selected from the group consisting of homopolypropylene, random copolymers of propylene and ethylene and / or butene-1, block polypropylene, propylene-α-olefin copolymers, propylene-ethylene-α-olefin copolymers, etc.

[0030] The content of the polypropylene resin is preferably 10% by mass or more from the viewpoint of improving cuttability, and preferably 60% by mass or less from the viewpoint of achieving both good stretchability, when the entire polyolefin film of the present invention is taken as 100% by mass.

[0031] <E’(50)> The polyolefin film of the present invention preferably has a storage modulus E'(50) of 0.5 GPa or less, more preferably 0.3 GPa or less, at 50°C under an amplitude strain of 0.05% and 10 Hz. By setting E'(50) to 0.5 GPa or less, the polyolefin film of the present invention can exhibit uniform and high stretchability when used as an expanding film.

[0032] <tanδピーク> A preferred embodiment for controlling the storage moduli E'(-20) and E'(50) of the polyolefin film of the present invention is one in which the polyolefin film of the present invention has a tan δ peak in the range of 10 to 50°C. A more preferred embodiment is one in which the film of the present invention has a tan δ peak in the range of 10 to 50°C, and the peak value is 0.15 or more. Here, the tan δ peak refers to the maximum value of the loss tangent (tan δ) measured by DMA (dynamic viscoelasticity measurement), and the loss tangent refers to the ratio (E" / E') of the storage modulus E' to the loss modulus E". The tan δ peak in the present invention is a value measured by DMA (dynamic viscoelasticity measurement) described in the Examples. When the film of the present invention has two or more tan δ peaks, it is preferable that at least one tan δ peak be in the range of 10 to 50°C.

[0033] By controlling the tan δ peak of the film within the range of 10 to 50°C, the temperature dependence of the storage modulus E' within the same temperature range becomes greater, and E'(-20) and E'(50) can be preferably controlled to the above-mentioned values. Furthermore, by controlling the peak value of the tan δ peak of the film of the present invention within the range of 10 to 50°C to 0.15 or more, the temperature dependence of the storage modulus E' becomes greater, and E'(-20) and E'(50) can be more preferably controlled. This maintains the stretchability during the expanding process while improving the cuttability when cutting the film in each process. From the same viewpoint, a tan δ peak value of 0.3 or more is more preferable.

[0034] A preferred method for controlling the tan δ peak of the polyolefin film of the present invention within the range of 10 to 50°C is to use a resin having a tan δ peak at 10 to 50°C in at least the thickest layer (or the entire film if it is a single layer) of the layers contained in the film of the present invention.Preferred examples of such resins include low-crystalline polypropylene, amorphous polypropylene, propylene-α-olefin copolymer, olefin-based elastomers such as 4-methyl-1-pentene-α-olefin, styrene-based elastomers, and mixed resins of styrene-based elastomers and softeners for adjusting the tan δ peak.

[0035] The α-olefin is preferably a linear or branched α-olefin having 2 to 20 carbon atoms, more preferably an α-olefin having 2 to 10 carbon atoms. The styrene-based elastomer preferably includes copolymers of styrene and dienes, such as styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), and styrene-butadiene-styrene copolymer (SBS), as well as hydrogenated products thereof (e.g., styrene-ethylene-butadiene-styrene copolymer (SEBS)). Also, styrene-isobutylene copolymers (e.g., styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), and mixtures thereof, such as styrene-isobutylene block copolymers, are preferred. When the styrene-based elastomer has a tan δ peak in the range of 10 to 50°C, it may be used alone as a resin for controlling the storage modulus. However, when the tan δ peak of the styrene-based elastomer is less than 10°C, it is preferable to use the elastomer in combination with a softener to adjust the tan δ peak. As the softener, one or more types selected from the group consisting of petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers, and alicyclic copolymers, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins, xylene resins, and hydrogenated products thereof can be preferably used.

[0036] More preferred examples of resins having a tan δ peak at 10 to 50°C for use in the polyolefin film of the present invention include amorphous polypropylene, 4-methyl-1-pentene-α-olefin copolymer, SEB, SEBS, SIB, and SIBS. Also more preferred examples include mixed resins of SEB and / or SEBS with the softeners, or mixed resins of SIB and / or SIBS with the softeners.

[0037] <Melting point> Another preferred embodiment in which E'(50) is controlled to 0.5 GPa or less is an embodiment in which the polyolefin film of the present invention has a melting point of 40 to 80° C. The melting point in the present invention refers to a value measured by DSC (differential scanning calorimetry) described in the examples.

[0038] By controlling the melting point of the polyolefin film of the present invention within the above range, the storage modulus E'(50) at 50°C can be reduced and suitably controlled while maintaining the cuttability and film stability at room temperature. Resins having a melting point of 40 to 80°C are preferably polyethylene resins such as low-crystalline ethylene-α-olefin copolymers; polypropylene resins such as propylene-α-olefin copolymers and propylene-ethylene-α-olefin copolymers; polybutene resins such as polybutene-1-ethylene copolymers and polybutene-1-propylene copolymers; and one or more selected from ethylene-ethyl (meth)acrylate copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene-n-butyl (meth)acrylate copolymers, and ethylene-vinyl acetate copolymers. The α-olefins are not particularly limited as long as they are copolymerizable with propylene or ethylene. Examples include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0039] <p2 p1> In the polyolefin film of the present invention, the tensile stress at 10% elongation is P1 (MPa) and the tensile stress at 200% elongation is P2 (MPa). From the viewpoint of improving the stretchability when the polyolefin film of the present invention is used in an expanding process, P2 / P1 is preferably 1.0 or more, more preferably 1.2 or more. Furthermore, from the viewpoint of stability after expansion, P2 / P1 is preferably 3.0 or less, more preferably 2.0 or less. The tensile elongation at break is calculated by conducting a tensile test in the machine direction (MD) and transverse direction (TD) of the film at 23°C and 300 mm / min using the method described in the Examples. Methods for controlling P2 / P1 within the above preferred range include using a resin suitable for each layer of the polyolefin film of the present invention, as described below. However, a more preferred method is to control P2 / P1 by using the material constituting the base layer, as described below.

[0040] <Haze> In general, film products are often inspected for defects caused by foreign matter contamination, surface scratches, etc. during or after production, and from the viewpoint of suppressing a decrease in the accuracy of defect detection during this inspection and suppressing a decrease in the yield of products manufactured using the polyolefin film of the present invention, it is preferable that the haze be 55% or less. The lower limit of the preferred range of haze is not particularly limited as long as it does not impair the effects of the present invention, but is substantially preferably 7% or more.

[0041] From the same viewpoint, the surface haze of the polyolefin film of the present invention is preferably 38% or less. The lower limit of the preferred range of the surface haze of the polyolefin film of the present invention is not particularly limited as long as it does not impair the effects of the present invention, but is substantially preferably 5% or more.

[0042] The haze and surface haze are measured as described in the Examples. Furthermore, when each layer of the polyolefin film of the present invention is made of two or more resins, the haze of the polyolefin film of the present invention can be controlled by adjusting the compatibility or viscosity of the resins, adjusting the surface roughness of the cast roll used in producing the polyolefin film, or embossing the surface during or after the production of the polyolefin film. When the layer located on the surface of the polyolefin film of the present invention is made of two or more resins, the surface haze of the polyolefin film of the present invention can be controlled by adjusting the compatibility or viscosity of the resins contained in the layer located on the surface, adjusting the surface roughness of the cast roll used in producing the polyolefin film, or embossing the surface during or after the production of the polyolefin film. In particular, from the viewpoint of reducing productivity and costs and reducing environmental impact, it is preferable to control the haze and surface haze of the polyolefin film of the present invention by adjusting the compatibility or viscosity of the resins used in each layer of the polyolefin film of the present invention.

[0043] <Static friction coefficient> In the polyolefin film of the present invention, from the viewpoint of reducing friction between the film and a processing device when expanding a dicing film using the polyolefin film of the present invention, thereby obtaining high extensibility, and from the viewpoint of improving process stability during production, the static friction coefficient between the A layer surfaces is preferably 0.6 or less, more preferably 0.4 or less. Furthermore, from the viewpoint of preventing slippage when the polyolefin film of the present invention is wound into a roll or stored, the static friction coefficient between the A layer surfaces is preferably 0.1 or more.

[0044] The static friction coefficient in the present invention refers to the static friction coefficient evaluated by the method described in the Examples. When both layers on the surface side of the polyolefin film of the present invention are Layer A, the static friction coefficient between the surfaces of at least one Layer A is preferably 0.6 or less and more preferably 0.1 or more.

[0045] Specific methods for controlling the static friction coefficient include controlling the material constituting the A layer and the manufacturing method, and specific examples will be described later.

[0046] <Film layer structure> The polyolefin film of the present invention is sufficient as long as it has a layer A satisfying the above (i) and (ii) on at least one side. It may be a film consisting of one layer (i.e., a single layer consisting of only layer A) or a film consisting of two or more layers, but it is more preferable that it is composed of two or more layers, and even more preferable that it is composed of three or more layers. When the polyolefin film of the present invention is composed of two or more layers, there is no particular limitation, but it is preferable that it has a base layer in addition to layer A. Furthermore, the polyolefin film of the present invention may be a two-layer film consisting of layer A and base layer, or it may contain other layers as needed as long as the effects of the present invention are not impaired. More preferred structures include a three-layer structure having layer A, base layer, and layer B described below in this order, a three-layer structure having layer A, base layer, and layer C described below in this order, and a four-layer structure having layer A, base layer, layer B, and layer C in this order.

[0047] <Thickness of polyolefin film> The thickness of the polyolefin film of the present invention can be adjusted appropriately depending on the required properties, but is preferably 10 to 200 μm, more preferably 20 to 150 μm, and particularly preferably 40 to 120 μm. If the thickness is thinner than 10 μm, the strength is insufficient, which may make it difficult to transport during the manufacturing process or may cause tearing during processing or use. If the thickness is thicker than 200 μm, the cuttability may be reduced.

[0048] <Base material layer> The substrate layer constituting one preferred example of the polyolefin film of the present invention will be described. The substrate layer is a layer containing at least a resin, and is a layer different from the A layer, B layer, and C layer referred to in the present invention. This substrate layer refers to a layer having a finite thickness, and is preferably a layer having excellent expandability in the film of the present invention.

[0049] Furthermore, the substrate layer is preferably the thickest layer among the layers contained in the polyolefin film of the present invention. The thickness of the substrate layer can be appropriately adjusted according to the required properties of the polyolefin film of the present invention, but is preferably 40% or more and 95% or less, assuming that the thickness of all film layers is 100%. If the thickness of the substrate layer is less than 40%, the expandability (stretchability, uniform stretchability) of the film of the present invention may be reduced. From the viewpoint of improving the expandability (stretchability, uniform stretchability) of the polyolefin film of the present invention, the thickness of the substrate layer is more preferably 50% or more, and even more preferably 60% or more. From the viewpoint of process stability during production and use of the polyolefin film of the present invention, the thickness of the substrate layer is more preferably 90% or less.

[0050] The resin used in the base layer of the polyolefin film of the present invention is not particularly limited, and thermoplastic resins such as polyolefin and polyester can be used, but it is preferable to use polyolefin as the main component from the viewpoints of environmental considerations, productivity, processability, etc. Here, using polyolefin as the main component means that the proportion of polyolefin is 50% by mass or more, more preferably 70% by mass or more, when the entire base layer is taken as 100% by mass.

[0051] The polyolefin may preferably be at least one selected from the group consisting of polyethylene-based resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and low-crystalline or amorphous ethylene-α-olefin copolymers; polypropylene-based resins such as homopolypropylene, random copolymers of propylene and ethylene and / or butene-1, block polypropylene, propylene-α-olefin copolymers, and propylene-ethylene-α-olefin copolymers; polybutene-based resins such as polybutene-1, polybutene-1-ethylene copolymers, and polybutene-1-propylene copolymers; 4-methyl-1-pentene-α-olefin copolymers; ethylene-ethyl (meth)acrylate copolymers; ethylene-methyl (meth)acrylate copolymers; ethylene-n-butyl (meth)acrylate copolymers; and ethylene-vinyl acetate copolymers. Examples of the α-olefin include propylene, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0052] Among the above-mentioned polyolefins, polyethylene-based resins, polypropylene-based resins, polybutene-based resins, and 4-methyl-1-pentene / α-olefin copolymers are more preferably used from the viewpoint of improving processability and expandability (stretchability, uniform stretchability).

[0053] Furthermore, from the viewpoint of controlling the above-mentioned P2 / P1 to 1.0 or more, when the base layer contains one or more resins selected from the group consisting of high-density polyethylene (HDPE), homopolypropylene, random copolymer of propylene and ethylene and / or butene-1, and block polypropylene, it is more preferable that the content of these resins is less than 50% by mass in total when the entire base layer is taken as 100% by mass.

[0054] As another more preferred embodiment of the base material layer constituting the polyolefin-based film of the present invention, from the viewpoint of controlling the storage elastic modulus E'(-20) and improving the processability and expandability, a configuration in which the base material layer contains 10% by mass or more of a polypropylene-based resin can be mentioned.

[0055] As other more preferred embodiments, from the viewpoint of controlling the storage elastic modulus E'(50) and improving the expandability, there are a method of using a resin having a tanδ peak in the range of 10 to 50°C, a method of using a resin having a tanδ peak in the range of 10 to 50°C and a peak value of 0.15 or more, and a method of using a resin having a melting point in the range of 40 to 80°C. Each of the above-mentioned preferred resins can be used for the base material layer.

[0056] Furthermore, as one particularly preferred embodiment of the base material layer of the olefin-based film of the present invention, when the entire base material layer is 100% by mass, it contains 70% by mass or more of a polyolefin-based resin, 10% by mass or more and less than 50% by mass of a polypropylene-based resin, and has a tanδ peak in the range of 10 to 50°C and contains 10% by mass or more of a resin having a peak value of 0.15 or more.

[0057] <A layer (slip layer)> Next, the A layer of the polyolefin-based film of the present invention will be described. The A layer is a layer containing at least a resin and is a layer disposed on at least one surface of the polyolefin-based film of the present invention. Also, this A layer refers to a layer having a finite thickness and is a layer having excellent slipperiness in the film of the present invention.

[0058] Thermoplastic resins such as polyolefin and polyester can be used for the A layer, but from the viewpoints of productivity and processability, etc., it is preferable to use polyolefin as the main component. Here, using polyolefin as the main component means that when the entire A layer is 100% by mass, the proportion of polyolefin is 50% by mass or more, and more preferably 70% by mass or more.

[0059] For Layer A, resins similar to the polyolefins suitable for the base layer described above can be preferably used. Among these, from the viewpoints of productivity, processability, and imparting excellent lubricity to the polyolefin film of the present invention, homopolypropylene, random copolymers of propylene and ethylene and / or butene-1, block polypropylene, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE) are preferably used.

[0060] In the polyolefin film of the present invention, methods for controlling the Spk+Svk of the surface of Layer A within the above-mentioned preferred range and controlling the static friction coefficient of the surface of Layer A within the above-mentioned preferred range to enhance the slipperiness include, for example, embossing the surface of Layer A during or after the film formation of the polyolefin film, using two or more incompatible resins in Layer A, or incorporating inorganic or organic particles into Layer A. The inorganic particles can be one or more inorganic particles selected from the group consisting of inorganic oxide particles (silica particles, alumina particles, titanium oxide particles, etc.), inorganic carbonate particles (calcium carbonate particles, barium carbonate particles, etc.), and inorganic silicate particles (aluminum silicate particles, talc particles, kaolin particles, etc.), and the organic particles can be one or more organic particles selected from the group consisting of acrylic resin particles, polyolefin resin particles (polyethylene resin particles, polypropylene resin particles), and polystyrene resin particles.

[0061] Of these methods for controlling Spk+Svk, from the viewpoint of improving productivity and reducing environmental impact, the method of using two or more incompatible resins in Layer A or the method of incorporating inorganic or organic particles in Layer A is more preferable, and from the viewpoint of suppressing process contamination due to particle shedding during processing and of controlling Spk and Svk to more preferably control the surface shape of Layer A, the method of using two or more incompatible resins in Layer A is even more preferable.

[0062] Furthermore, from the viewpoint of favorably controlling the indentation hardness and enhancing the ease of sliding, it is particularly preferable that the layer A of the present invention contains one or more polypropylene-based resins a1 selected from homopolypropylene, random copolymers of propylene and ethylene and / or butene-1, and block polypropylene, in combination with high-density polyethylene (HDPE) that is incompatible with the polypropylene-based resin a1.

[0063] When polypropylene resin a1 and high-density polyethylene are used in combination in Layer A, the proportion of polypropylene resin a1 used in Layer A is preferably 10% by mass or more, and more preferably 20% by mass or more, when the entire Layer A is taken as 100% by mass, from the viewpoint of favorably controlling the indentation hardness and the aforementioned E'(-20). Similarly, from the viewpoint of improving lubricity, the proportion of high-density polyethylene used in Layer A is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more.

[0064] When polypropylene resin a1 and high-density polyethylene are used in combination in layer A, in order to improve the Spk+Svk to 0.5 μm or more, the temperature is set at 230 ° C. and a shear rate of 122 s -1 Similarly, from the viewpoint of controlling the Spk+Svk to 3.0 μm or less, controlling the haze of the polyolefin film of the present invention to 55% or less, and controlling the surface haze of the polyolefin film of the present invention to 38% or less, it is preferable that the difference in melt viscosity between the polypropylene resin a1 and the high-density polyethylene at 230° C. and a shear rate of 122 s -1 The difference in melt viscosity between the polypropylene-based resin a1 and high-density polyethylene in [[ ]] is preferably 850 Pa·s or less. The melt viscosity is evaluated by the method described in the examples. Further, from the viewpoint of enhancing the slipperiness, it is more preferable that the melt viscosity of high-density polyethylene is higher than that of the polypropylene-based resin a1. That is, the melt viscosity of high-density polyethylene is more preferably 300 Pa·s or more and 850 Pa·s or less higher than the viscosity of the polypropylene-based resin a1, and particularly preferably 500 Pa·s or more and 750 Pa·s or less higher. When two or more types of polypropylene-based resins a1 are used in the A layer or two or more types of high-density polyethylene are used, the melt viscosity can be evaluated using a resin obtained by previously melt-kneading the polypropylene resins a1 or the high-density polyethylenes with each other.

[0065] In addition to those described above, in the A layer of the present invention, lubricants such as fatty acid amides, metal soaps, fluorine-based polymers, silicone-based lubricants, fatty acids, and vegetable oils may be added to improve the slipperiness within a range that does not impair the effects of the present invention.

[0066] The thickness of the A layer can be appropriately adjusted according to the required characteristics of the film of the present invention. However, when the total thickness of the film of the present invention is taken as 100%, it is preferably 5% or more and 20% or less. When the thickness of the A layer is less than 5%, when the film of the present invention is formed into a film, it becomes a thin film lamination, and the difficulty of production increases, or the slipperiness that is the effect of the A layer may not be sufficiently exhibited. Also, when the layer composition of the A layer exceeds 20%, the expandability (stretchability, uniform stretchability) of the polyolefin-based film of the film of the present invention may become insufficient.

[0067] <B layer (dicing layer)> The B layer in the present invention refers to a layer containing at least a resin and having a finite thickness. Furthermore, when the polyolefin film of the present invention is used for wafer dicing, the B layer is disposed between the base layer of the polyolefin film and the surface to which the wafer is attached. The B layer is preferably used because it suppresses the generation of cutting debris during dicing using a blade dicing method and exhibits excellent dicing properties. However, the B layer may also be provided in dicing films for other purposes, such as laser dicing or scribe-and-break dicing.

[0068] When the polyolefin film of the present invention is used for blade dicing, an olefin elastomer is preferably used as the resin for Layer B. By using an olefin elastomer, cutting debris during dicing is suppressed and sufficient stretchability is obtained.

[0069] Although known olefin elastomers can be used as the olefin elastomer, it is preferable to use one or more α-olefin elastomers selected from the group consisting of ethylene elastomers, propylene elastomers, 1-butene elastomers, and 4-methylpentene-1 elastomers (propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-ethylene-1-butene copolymers, 1-butene homopolymers, 1-butene-ethylene copolymers, 1-butene-propylene copolymers, 4-methylpentene-1 homopolymers, 4-methylpentene-1-propylene copolymers, 4-methylpentene-1-1-butene copolymers, 4-methylpentene-1-propylene-1-butene copolymers, and combinations thereof). From the viewpoint of reducing cutting debris during dicing, propylene elastomers and 1-butene elastomers are particularly preferred, with propylene elastomers being particularly preferred.

[0070] In addition, the B layer may be used in combination with one or more resins selected from the group consisting of these α-olefin-based elastomers and LLDPE, LDPE, HDPE, homopolypropylene, random copolymers of propylene and ethylene and / or butene-1, block polypropylene, propylene-α-olefin copolymers, and propylene-ethylene-α-olefin copolymer polypropylenes.

[0071] The thickness of the B layer can be appropriately adjusted according to the required properties of the polyolefin-based film of the present invention. However, when the total thickness of the film of the present invention is taken as 100%, it is preferably a layer structure of 10% or more and 25% or less. If the layer structure of the B layer is less than 10%, when the film of the present invention is formed, it becomes a thin film laminate, and the difficulty of production increases, or the cutting property that is the effect of the B layer may not be sufficiently exhibited. Further, if the layer structure of the B layer exceeds 25%, the stretchability of the polyolefin-based film of the present invention may become insufficient.

[0072] <C layer (adhesive layer)> In addition to the above-described base material layer, A layer, and B layer, the polyolefin-based film of the present invention can have a C layer having adhesiveness disposed on the outermost layer.

[0073] For the C layer, any material such as crosslinked types such as acrylic and silicone, non-crosslinked types or pseudo-crosslinked types (thermoplastic types) such as natural rubber and synthetic rubber can be used. For example, when producing a polyolefin-based film including the C layer by coextrusion, it is preferable to use a thermoplastic resin as the main component from the viewpoint of recyclability. Here, using a thermoplastic resin as the main component means that the proportion of the thermoplastic resin in the composition is 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more.

[0074] Resins suitable for the C layer include styrene-based elastomers such as copolymers of styrene and dienes, such as styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), and styrene-butadiene-styrene copolymer (SBS), as well as their hydrogenated products (e.g., styrene-ethylene-butadiene-styrene copolymer (SEBS)), and styrene-isobutylene copolymers (e.g., styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), or mixtures thereof, and styrene-isobutylene block copolymers); polyethylene-based resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ethylene-α-olefin copolymers; polypropylene-based resins such as propylene-α-olefin copolymer and propylene-ethylene-α-olefin copolymer; and polybutene-based resins such as polybutene-1-ethylene copolymer and polybutene-1-propylene copolymer. In addition to the resin suitable for the C layer described above, it is more preferable to further contain a tackifier such as a petroleum resin such as an aliphatic copolymer, an aromatic copolymer, an aliphatic-aromatic copolymer, or an alicyclic copolymer, a terpene resin, a terpene phenol resin, a rosin resin, an alkylphenol resin, a xylene resin, or a hydrogenated product thereof, in order to enhance the adhesiveness of the adhesive layer.

[0075] <Additives> Each layer of the polyolefin film of the present invention may contain, as necessary, particles other than those described above, lubricants, crystal nucleating agents, antioxidants, heat resistance agents, weather resistance agents, antistatic agents, etc. The amount of these components added is preferably 5% by mass or less, and more preferably 3% by mass or less, when the total mass of each layer is taken as 100% by mass.

[0076] <Manufacturing method> Next, a method for producing the polyolefin film of the present invention will be described. The method for producing the polyolefin film of the present invention is not particularly limited. For example, in the case of a two-layer structure ("Layer A, base layer"), a three-layer structure ("Layer A, base layer, B"), or a three-layer structure ("Layer A, base layer, C"), examples include a so-called coextrusion method in which the resins constituting each layer are melt-extruded from separate extruders and laminated together in a die, and a method in which each of the above layers is melt-extruded separately and then laminated by a lamination method. From the viewpoint of productivity, however, production by a coextrusion method is more preferred. Regarding coextrusion methods, known methods such as inflation and T-die methods are used, but from the viewpoints of excellent thickness accuracy and surface shape control, hot-melt coextrusion using a T-die method is more preferred. Furthermore, from the viewpoints of controlling the tensile elongation at break within the above-mentioned preferred range and reducing the environmental impact during production, it is particularly preferred that the production method for the polyolefin film of the present invention does not include a heat-stretching step such as sequential biaxial stretching or simultaneous biaxial stretching.

[0077] As a manufacturing method other than the above, after "Layer A and base layer" or "Layer A, base layer and layer B" are manufactured by hot melt co-extrusion, Layer C can be provided by coating or laminating.

[0078] <Application> The polyolefin film of the present invention can be preferably used as an industrial film or packaging film such as a protective film or a process film, but because of its excellent stretchability and expandability, it can be more preferably used as a protective film when drawing metal, a process film when dicing and expanding semiconductor wafers, or a constituent member of a pouch-shaped or cup-shaped aluminum laminate packaging film, and in particular, because of its excellent expandability and cuttability, it can be more preferably used for dicing and expanding semiconductor wafers.In addition to these, it can also be suitably used as a film for other semiconductor manufacturing processes, for example, by transferring a semiconductor wafer after dicing or expanding to a process film containing the polyolefin film of the present invention and storing or transporting it. [Example]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Measurements and evaluations of various physical properties were carried out by the following methods, and unless otherwise specified, the measurements were carried out indoors at 23°C and 65% RH.

[0080] (1) Thickness of each layer A cross-sectional slice of the polyolefin film was prepared using a microtome, and the cross-section was coated with platinum to prepare an observation sample. Next, the film cross-section was observed at an arbitrary magnification using a field emission scanning electron microscope (S-4800) manufactured by Hitachi, Ltd., and the thicknesses of Layer A, the base layer, and Layer B were measured.

[0081] (2) Melt viscosity Using a Toyo Seiki Capillograph (1D), the temperature was 230°C and the shear rate was 122 s -1 The melt viscosities of the polypropylene resin and polyethylene resin used in the examples and comparative examples were measured.

[0082] (3) Crystallization temperature, melting point In accordance with JIS K-7121 (2012), the resins used in the examples and comparative examples were measured under the following conditions using a differential scanning calorimeter (EXSTAR DSC6220 manufactured by Seiko Instruments Inc.), and the crystallization temperature was determined from the differential scanning calorimetry curve obtained in step (iii), and the melting point was determined from the differential scanning calorimetry curve obtained in step (v). Sample amount: 3 mg Heating rate, cooling rate: 20℃ / min Temperature program: step (i) increasing the temperature from 30°C to 250°C, step (ii) maintaining at 250°C for 5 minutes, step (iii) decreasing the temperature from 250°C to -30°C, step (iv) maintaining at -30°C for 5 minutes, step (v) increasing the temperature from -30°C to 250°C.

[0083] (4) Indentation hardness Using an Elionix nanoindentation tester ENT-2100, indentation tests were carried out on the surfaces of layers A and B of polyolefin-based films using a load-unload test under the following conditions: For each type of film, an arbitrary point was set as the base point, and measurements were taken at 1 mm intervals in the cross direction in MD and TD, three points on each side (13 points in total), from this base point (13 points in total). Of the indentation hardness values obtained, the top two and bottom two points were excluded, and the average of six measurements was taken as the indentation hardness of the surface of layers A or B of the polyolefin-based film. Indenter: Elionix Berkovich indenter (triangular pyramid tip, made of diamond) Temperature: 26℃ Maximum load: 0.10mN Loading speed / unloading speed: 0.01mN / s Load at the start of the load-unload test: 0 mN Hold time at maximum load: 1 second Surface detection method: Tilt method Surface detection threshold factor: 1.5 Spring compensation: Real-time spring compensation.

[0084] (5) Spk+Svk The surfaces of layers A and B of the polyolefin film were measured using a Hitachi High-Tech Science Corporation scanning white light interference microscope (VS1540) in accordance with ISO25178-2 (2012) under the following conditions and with the following equipment configuration. The images were interpolated (fully interpolated) using the accompanying analysis software, and surface correction was performed using a polynomial fourth-order approximation. Then, the protruding peak height Spk (μm) and protruding valley depth Svk (μm) were calculated using a median filter (3 x 3 pixels). Five measurements were performed for each type of film, and the arithmetic mean of Spk + Svk (μm) for the five points was taken as the Spk + Svk (μm) of the polyolefin film.

[0085] <Measurement conditions and equipment configuration> Objective lens: 10x Telescope tube: 1x Zoom lens: 1x Wavelength filter: 530nm white Measurement mode: Wave Measurement software: VS-Measure 10.0.4.0 Analysis software: VS-Viewer 10.0.3.0 Measurement range: 1009.7 μm x 1010.5 μm (The above range was measured by connecting 2 fields of view x 2 fields of view, a total of 4 fields of view) Number of pixels: 1842 x 1844.

[0086] (6) Tensile elongation at break, P2 / P1 Tensile tests were performed five times in each of the machine direction (MD) and transverse direction (TD) of the film at 23°C and a speed of 300 mm / min using a tensile testing machine (Orientec, Universal Testing Machine, Tensilon) according to JIS K 7113 (1995). The arithmetic mean of the tensile elongation at break (arithmetic mean of 10 points) was used as the tensile elongation at break of the polyolefin film. The test specimens used for the measurements were rectangular, 10 mm wide and 100 mm long, with a chuck distance of 30 mm. The stress P1 (MPa) at 10% elongation and the stress P2 (MPa) at 200% elongation were calculated from the arithmetic mean of 10 points, as described above, and the P2 / P1 ratio of the polyolefin film was calculated using these values.

[0087] (7) Storage modulus E', loss tangent tanδ The films were cut into 10 mm wide rectangles, and measurements were performed five times each in the machine direction (MD) and transverse direction (TD) (10 times in total) for each type of film using a Seiko Instruments Inc. DMS6100 dynamic viscoelasticity measuring device under the following conditions based on the tensile vibration-non-resonance method of JIS K7244-4 (1999) (this is referred to as the dynamic viscoelasticity method). The storage modulus E' (-20) (MPa) at -20°C, the storage modulus E' (50) (MPa) at 50°C, and the loss tangent tanδ between 10 and 50°C were then determined from the arithmetic mean values of 10 points, including the presence or absence of peaks and, if any, the temperature and peak value. Measurement mode: Tensile Test piece width: 5mm Frequency: 10Hz Amplitude distortion: 0.05% Measurement temperature: -50℃ to 100℃ Heating rate: 3°C / min.

[0088] (8) Coefficient of static friction After conditioning the film at 23°C and 65% RH, it was cut into a strip of 75 mm wide and 100 mm long, with the longitudinal direction of the film production line, to prepare a sample. The slip coefficient was measured in an atmosphere of 23°C and 65% RH using a slip coefficient measuring device (Model ST-200, manufactured by Techno Needs Corporation).

[0089] Specifically, a sample cut into a strip was placed on the measurement sample stage of the device so that the pulling direction was the longitudinal direction and the surfaces of the A layers to be evaluated overlapped and in contact, and the end of the sample was fixed to the load detection U-gauge of the device.The film was then left to stand, and a 400g weight with a 6.5cm x 6.5cm Teflon (registered trademark) sheet attached to the sample contact surface was placed on top of it to bring the samples into close contact with each other.The static friction coefficient was measured 10 times when the upper film was pulled under the following conditions, and the average of the 6 measurements, excluding the top 2 and bottom 2 points, was taken as the static friction coefficient of the polyolefin film. Measurement distance: 15mm Measurement speed: 300mm / min.

[0090] (9) Hayes Using a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.), measurements were taken five times for each type of film in accordance with JIS K 7136 (2000), and the average value was taken as the haze (%) of the polyolefin film.

[0091] (10) Surface haze Using a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.), the internal haze was measured in accordance with JIS K 7136 (2000) with the film placed in a quartz cell filled with pure water to eliminate light scattering due to unevenness on the film surface. Measurements were performed five times for each type of film, and the average value was calculated. Furthermore, the value obtained by subtracting the internal haze from the haze of the polyolefin-based film calculated in (9) was taken as the surface haze (%) of the polyolefin-based film.

[0092] (11) Expand test, stretchability A 150mm diameter silicon wafer (chip) diced into 25mm squares was attached to the B-side of the polyolefin film using double-sided tape. The wafer was then placed in a Hugle expander so that the center of the stage was aligned with the center of the silicon wafer, as shown in Figure 1. The expansion was performed at a stage temperature of 23°C, a stage height of 50mm, and a stage speed of 6mm / s. The inter-chip distances L1 and L2 (mm) were then measured at four locations for the four central chips, as shown in Figure 2, and the inter-chip distance was calculated from the arithmetic mean of the four measurements. Five expansion tests were performed for each type of film, and the arithmetic mean inter-chip distance L (mm) was used to evaluate the extensibility of the wafer center (expansion of chip spacing) according to the following criteria: ● indicates the best performance, followed by ◎, ◯, and △. Stretchability evaluation criteria ●:L is 1.4mm or more ◎: L is 1.2 mm or more and less than 1.4 mm 〇: L is 0.9mm or more and less than 1.2mm △: L is less than 0.9 mm.

[0093] (12) Evaluation of cutting ability The film was cut into a circle with a diameter of 150 mm from the A layer side using an OLFA rotary compass cutter. The condition of the cut circumference was visually inspected to check for cutting defects such as notches, whiskers, and stretching of the film, and the film's cutting ability was evaluated according to the following criteria. The blade was replaced with a new one after each measurement. ◎: Defective cutting occurred in less than one-eighth of the circumference ○: The cutting defect was less than one-fourth of the circumference. △: Defective cutting occurred in more than one-fourth of the circumference.

[0094] The resins used in the examples and comparative examples are shown below.

[0095] <hpp> Melt viscosity 410 Pa·s (temperature 230°C, shear rate 122 s -1 (Measured at 113°C. The same applies below.) Commercially available homopolypropylene with a crystallization temperature of 113°C and a melting point of 165°C. <rpp> A commercially available metallocene-based random polypropylene with a melt viscosity of 510 Pa·s, a crystallization temperature of 101°C, and a melting point of 136°C. <bpp> Commercially available block polypropylene with a melt viscosity of 370 Pa·s, a crystallization temperature of 120°C, and a melting point of 164°C <hdpe1> Melt viscosity 1090 Pa s, crystallization temperature 116°C, melting point 136°C, density 0.960 g / cm 3 of commercially available high density polyethylene <hdpe2> Melt viscosity 1290 Pa s, crystallization temperature 114°C, melting point 132°C, density 0.962 g / cm 3 of commercially available high density polyethylene <ldpe> Melt viscosity 310 Pa s, crystallization temperature 92°C, melting point 107°C, density 0.918 g / cm 3 of commercially available low density polyethylene <lldpe> Melt viscosity 820 Pa s, crystallization temperature 96°C, melting point 113°C, density 918 g / cm 3 Commercially available linear low density polyethylene <emaa> Melt viscosity 220 Pa·s, acid content 11%, crystallization temperature 65°C, melting point 89°C, density 940 g / cm 3 Commercially available ethylene-methacrylic acid copolymers <tpe> Styrene-based elastomer manufactured by Asahi Kasei, trade name "S.O.E." S1605, density 1.0 g / cm 3 , MFR 5 g / 10 min (measured at 230 °C), no melting point and crystallization temperature.

[0096] <PE particle MB> High molecular weight polyethylene fine particles "Mipelon" (registered trademark) PM200 manufactured by Mitsui Chemicals with an average particle diameter of 10 μm and the said BPP were kneaded at 230 °C using a twin-screw extruder so that the mass ratio became 10:90, and a masterbatch of polyethylene particles was produced.

[0097] <Example 1> The constituent resins of each layer described in Table 1 were put into each extruder of a T-die composite film-making machine with a multi-manifold having three extruders of φ65 mm (for A layer), φ115 mm (for base material layer), and φ90 mm (for B layer) and a die width of 2,400 mm. The discharge amount of each extruder was adjusted so that the thickness ratio of the A layer was 10%, the thickness ratio of the base material layer was 80%, and the thickness ratio of the B layer was 10%. Extrusion was carried out from the composite T-die at an extrusion temperature of 230 °C each, and the surface of the B layer was brought into contact with a mirror-finish casting roll at 30 °C, and a polyolefin-based film with a three-layer structure having a film thickness of 100 μm in which the A layer, the base material layer, and the B layer were laminated in this order was produced.

[0098] <Examples 2 to 7, Comparative Examples 1 to 4> A polyolefin-based film was produced in the same manner as in Example 1, except that the constituent resins of each layer were as described in Tables 1 and 2.

[0099]

Table 1

[0100]

Table 2

[0101] Example 1 exhibited excellent stretchability when the diced wafer was expanded, allowing the chip spacing at the center of the wafer to be sufficiently widened, and also exhibited good cuttability. Examples 2 and 3 exhibited even better stretchability than Example 1. Examples 4 and 5 exhibited excellent stretchability and improved yield compared to Example 2. Furthermore, in comparison with Examples 6 and 7, Examples 4 and 5 also exhibited excellent yields. Note that Example 7 exhibited a slightly inferior yield compared to Example 6. On the other hand, Comparative Examples 1 to 4 exhibited low indentation hardness of Layer A, resulting in poor stretchability and poor yield. [Explanation of symbols]

[0102] 1 chip 2 Stage 3 Corner of the Stage< / tpe> < / emaa> < / lldpe> < / ldpe> < / bpp> < / rpp> < / hpp>

Claims

1. A polyolefin film having a layer A that satisfies (i) and (ii) on at least one side thereof and having a tensile elongation at break of 250% or more. (i) In a loading / unloading test using nanoindentation, the surface indentation hardness is 40 MPa or more and 150 MPa or less. (ii) The sum of the protruding peak height Spk and the protruding valley depth Svk, Spk+Svk, is 0.5 μm or more and 3.0 μm or less.

2. 2. The polyolefin film according to claim 1, wherein the storage modulus E'(-20) at -20°C is 1.8 GPa or more and the storage modulus E'(50) at 50°C is 0.3 GPa or less.

3. 3. The polyolefin film according to claim 1, wherein P2 / P1 is 1.0 or more and 3.0 or less, where P1 (MPa) is the tensile stress at an elongation of 10% and P2 (MPa) is the tensile stress at an elongation of 200%.

4. The polyolefin film according to claim 1 or 2, having a haze of 7% or more and 55% or less.

5. The polyolefin film according to claim 1 or 2, having a surface haze of 5% or more and 38% or less.

6. The polyolefin film according to claim 1 or 2, wherein when the entirety of layer A is taken as 100% by mass, layer A contains a polypropylene resin as a main component and 10% by mass to 40% by mass of a polyethylene resin having a melting point of 125°C or higher, and the melt viscosity of the polyethylene resin is 300 Pa s to 850 Pa s higher than the melt viscosity of the polypropylene resin. －１ The value is measured using a capillary flow tester under the conditions above.

7. 3. The polyolefin film according to claim 1, wherein the coefficient of static friction between the surfaces of the A layers is 0.1 or more and 0.6 or less.

8. The polyolefin film according to claim 1 or 2, which is used for wafer dicing or wafer expanding.

9. A film for use in semiconductor manufacturing processes, comprising the polyolefin film according to claim 1 or 2.

10. A method for manufacturing a semiconductor chip using the semiconductor manufacturing process film according to claim 9.

11. A manufacturing apparatus for manufacturing semiconductor chips using the semiconductor manufacturing process film according to claim 9.

Images