Semiconductor Wafer Protection Film

Abstract

To provide a semiconductor wafer protection film that suppresses gloss and makes it easy to detect defects such as foreign matter and fisheyes. The semiconductor wafer protection film has a corrugated cross section with alternating convex and concave portions, each of which is 1 cm 2 The size of the convex and concave portions in plan view is 0.3 to 3.0 mm. 2 The surface roughness Ra is set to 0.1 to 0.4 μm. It is preferable that there is a flat portion between the convex portion and the concave portion.

Description

[Technical Field]

[0001] The present invention relates to a semiconductor wafer protection film that is inserted between semiconductor wafers when the semiconductor wafers are stacked and stored in a container. [Background technology]

[0002] Semiconductor wafers are generally disk-shaped thin slices of silicon ingots, typically ranging from 2 to 18 inches. Circuit patterns are formed on the surface of the semiconductor wafer, which is then cut into chips and packaged to produce semiconductor devices such as LSIs. The process of slicing silicon ingots, the process of forming circuits on semiconductor wafers, and the process of cutting the semiconductor wafers with the formed circuits into chips and packaging them are often carried out in different locations. Typically, dedicated semiconductor wafer storage containers are used to transport semiconductor wafers from the location where one process is performed to the location where another process is performed. Semiconductor wafer storage containers include containers for stacking and storing semiconductor wafers. Specifically, these containers have a cylindrical storage section on the container body, cushioning materials on the top and bottom tiers, semiconductor wafers are stacked with semiconductor wafer protection films in between, and a lid is placed over them to keep them sealed. Semiconductor wafer protective films are used to prevent scratches caused by contact between semiconductor wafers. For this reason, it is preferable to apply an embossing process with relatively large irregularities to the semiconductor wafer protective film (see Patent Document 1). Furthermore, because semiconductor wafers are sensitive to static electricity, semiconductor wafer protective films often contain conductive carbon black to impart antistatic properties or conductivity. Semiconductor wafer protective films are required to have few defects such as foreign matter contamination and fisheyes. However, embossed semiconductor wafer protection films have a strong gloss due to their surface shape, which makes it difficult to detect defects such as foreign matter and fisheyes. In particular, in semiconductor wafer protection films that are black and contain conductive carbon black, the combination of their color and gloss makes it even more difficult to detect defects such as foreign matter and fisheyes.

[0003] Furthermore, even if the semiconductor wafer protective film is stored sealed for a long period of time, it is required that the surface irregularities be restored when the lid is opened. If the irregularities are not restored, the semiconductor wafer protective film will stick to the semiconductor wafer, impairing the semiconductor wafer's pick-up ability. Therefore, high-density polyethylene is suitable as the synthetic resin constituting the semiconductor wafer protective film because it can be formed into a clear irregularity at high temperatures and has good stiffness and excellent restorability. However, some grades of high-density polyethylene have a stronger gloss than other synthetic resins, which makes it difficult to detect defects such as foreign matter contamination and fisheyes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-71878 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above-mentioned problems, the present invention provides a semiconductor wafer protection film that suppresses gloss and makes it easy to detect defects such as foreign matter and fisheyes. [Means for solving the problem]

[0006] That is, the present invention solves the above-mentioned problems by providing a semiconductor wafer protection film having a corrugated cross section in which convex portions and concave portions are alternately arranged, and each of the convex portions and concave portions has an area of ​​1 cm2 The size of the convex and concave portions in plan view is 0.3 to 3.0 mm. 2 and the surface roughness Ra is 0.1 to 0.4 μm. [Effects of the Invention]

[0007] By setting the surface roughness Ra of the semiconductor wafer protection film to 0.1 to 0.4 μm, the semiconductor wafer protection film becomes matte and gloss is suppressed, making it possible to provide a semiconductor wafer protection film in which defects such as foreign matter and fisheyes can be easily detected. Furthermore, even in the case of a semiconductor wafer protection film that is black, if the surface roughness Ra is set to 0.1 to 0.4 μm, the accuracy of detecting defects such as foreign matter and fisheyes can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a semiconductor wafer protection film according to the present invention. [Figure 2] 1 is a partially enlarged cross-sectional view of a semiconductor wafer protection film according to the present invention. [Figure 3] FIG. 10 is a perspective view showing an example of storing semiconductor wafers. [Figure 4] 10 is a cross-sectional view showing an example of storing semiconductor wafers. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] The semiconductor wafer protection film 1 of the present invention is prepared by placing cushion material 3 on the bottom of a container body 4 as shown in Fig. 3, stacking semiconductor wafer protection films 1 and semiconductor wafers 2 alternately on top of it, and then placing cushion material 3 on top, and then closing the container lid 5 as shown in Fig. 4. When closing the container lid 5, pressure is applied to the semiconductor wafers 2 so that they do not move within the container.

[0011] The semiconductor wafer protection film 1 of the present invention is a film whose main component is synthetic resin, and has recesses and protrusions formed on the front and back surfaces. 1 and 2, the semiconductor wafer protection film 1 of the present invention has a corrugated cross section in which convex portions 8 and concave portions 9 are alternately arranged. For example, when a rectangle is drawn by connecting the centers of four adjacent convex portions 8 with lines, the concave portions 9 are included in the rectangle. In this case, the rectangle does not need to be a square, and may be a rectangle, a diamond, or the like.

[0012] Convex part 8 and concave part 9 are 1cm each 2 The size of one convex portion 8 and one concave portion 9 in plan view is 0.3 to 3.0 mm. 2 is. By setting the density and size of the convex portions 8 and concave portions 9 within the above ranges, it is possible to prevent the semiconductor wafer from being damaged even if the semiconductor wafer is stored under pressure.

[0013] It is preferable that a flat portion 7 is present between the convex portion 8 and the concave portion 9. If the semiconductor wafer protective film 1 has the flat portion 7, when the semiconductor wafer 2 and the semiconductor wafer protective film 1 are stored in a container 6 and pressure is applied in the thickness direction of the semiconductor wafer 2, the semiconductor wafer protective film 1 is more likely to deform into a flat or nearly flat shape, thereby further improving scratch resistance for the semiconductor wafer 2. The area ratio occupied by such flat portion 7 is preferably 60% or more of the planar area of ​​the wafer protective film 1.

[0014] The thickness of the semiconductor wafer protection film 1 of the present invention is preferably 60 to 150 μm, and more preferably 80 to 120 μm. If the thickness is less than 60 μm, there is a risk of insufficient protection of the semiconductor wafers 2. On the other hand, if the thickness is more than 150 μm, the thickness increases, which may make it difficult to store the specified number of semiconductor wafers 2 in the container.

[0015] As the synthetic resin constituting the semiconductor wafer protection film 1, an olefin resin is preferable, and a polyethylene resin is more preferable. Examples of polyethylene resins include low-density polyethylene and high-density polyethylene, with high-density polyethylene being particularly preferred. High-density polyethylene has a high melting point, allowing it to be molded into concave and convex shapes at high temperatures, resulting in the formation of distinct concave and convex shapes. Furthermore, high-density polyethylene has excellent stiffness. Therefore, even when used in a compressed and sealed state for a long period of time, it returns to its original shape when the lid is opened, preventing it from sticking to the semiconductor wafer, providing excellent semiconductor wafer pickup properties. The semiconductor wafer protection film 1 of the present invention may have a two-kind three-layer structure consisting of an intermediate layer and two outer layers.

[0016] The semiconductor wafer protective film 1 of the present invention preferably contains an antistatic agent. The antistatic agent is an agent that prevents adhesion of dust and the like to the semiconductor wafer protective film 1 and efficiently releases static electricity generated by friction between the semiconductor wafer 2 and the semiconductor wafer protective film 1. 12 The antistatic agent is kneaded into the synthetic resin so that the resistance is Ω or less. Examples of such an antistatic agent include low-molecular-weight antistatic agents such as conductive carbon black, graphite carbon, carbon fiber, metal powder, metal oxide powder, metal-coated materials, non-electrostatic ethylene copolymer ionomer resins with alkali metal ions, and surfactants, as well as high-molecular-weight antistatic agents. Of these, carbon black is preferred from the viewpoint of inhibiting corrosion of semiconductor wafers. The content of carbon black is not particularly limited. 4 ~10 9 It should be adjusted to be Ω.

[0017] The semiconductor wafer protective film 1 of the present invention has a surface roughness Ra of 0.1 to 0.4 μm. The surface roughness Ra in the present invention is the surface roughness Ra measured by white light interferometry at a magnification of 400, but will be referred to simply as "surface roughness Ra" in this specification. When the surface roughness Ra is 0.1 to 0.4 μm, the surface of the semiconductor wafer protective film 1 becomes rough, and light is diffusely reflected, thereby reducing gloss. Furthermore, the reduced gloss makes it easier to detect defects such as foreign matter and fisheyes. If the surface roughness Ra is less than 0.1 μm, the surface is highly smooth, making it difficult for diffuse reflection to occur and gloss to be suppressed. This is undesirable because it makes it difficult to detect foreign matter or defects. On the other hand, if Ra exceeds 0.4 μm, the synthetic resin film and adhesive roll may not adhere well to each other during the particle removal process of the synthetic resin film before embossing, making it difficult to remove particles. If particle removal is insufficient, the particles may adhere to the embossing roll, creating unevenness that may result in defects.

[0018] Methods for making the surface roughness Ra of the semiconductor wafer protection film 1 0.1 to 0.4 μm include roughening the synthetic resin film before embossing by forming it at a temperature slightly lower than the molding temperature of general resins, or forming it using a matte-finished roll.

[0019] As described above, the semiconductor wafer protective film 1 of the present invention is a film with a corrugated cross section having clearly visible irregularities, making it difficult to detect defects such as foreign matter and fisheyes due to the irregularities and gloss. In particular, when flat portions 7 are present between convex portions 8 and concave portions 9, the surface irregularities are even more noticeable. Furthermore, when carbon black is added to the semiconductor wafer protective film 1, the film exhibits a dark color with an L value of less than 30 or a black color with an L value of less than 10, and the combination of this color and high gloss makes it even more difficult to detect defects such as foreign matter and fisheyes. Therefore, in the present invention, the surface of the semiconductor wafer protective film 1 is roughened to have a surface roughness Ra of 0.1 to 0.4 μm, giving it a matte finish. This suppresses gloss and makes it easier to detect foreign matter and fisheyes, even if the semiconductor wafer protective film 1 has the surface condition described above, even if it is a dark color with an L value of less than 30 or a black color with an L value of less than 10.

[0020] The method for producing the semiconductor wafer protection film 1 of the present invention will be described below with reference to an example. First, a synthetic resin film of uniform thickness is formed by inflation or extrusion. The resulting synthetic resin film is then heat-embossed. Specifically, the synthetic resin film is heated to a softening temperature and fed through a pair of rolls with numerous protrusions at offset positions. Convex portions 8 are formed in the areas where the protrusions press from the back surface of the synthetic resin film toward the front surface, and conversely, concave portions 9 are formed in the areas where the protrusions press from the front surface of the synthetic resin film toward the back surface. The synthetic resin film with the concave and convex shapes is then cut to fit the size of the semiconductor wafer 2, thereby obtaining the semiconductor wafer protection film 1 of the present invention as shown in Fig. 1. The dimensions of the semiconductor wafer protection film 1 do not need to be the same as those of the semiconductor wafer 2, but it is preferable to make them approximately the same as those of the semiconductor wafer 2 so that uneven force is not applied to localized parts of the semiconductor wafer 2. [Example]

[0021] The raw materials used in the examples and comparative examples are as follows. <Both outer layers> Resin: High-density polyethylene (product number: Creolex T4125, manufactured by Asahi Kasei Corporation) Antistatic agent 1: Carbon black (product number: Ketjenblack EC300J, manufactured by Lion Specialty Chemicals Co., Ltd.) Antistatic agent 2: Polymer antistatic agent (Entira SD100, manufactured by Mitsui Dow Polychemicals) <Middle layer> Resin: High-density polyethylene (product number: Creolex T4125, manufactured by Asahi Kasei Corporation)

[0022] [Example 1] Using an inflation co-extruder, a three-layer synthetic resin film with a thickness of 100 μm (two outer layers 20 μm, a middle layer 60 μm) was formed using the composition shown in Table 1. The synthetic resin film formation temperature was 155°C. Next, the obtained sheet was heated and embossed using a pair of rolls with numerous protrusions to form an uneven sheet with numerous convex and concave portions, which was then cut using an 8-inch diameter press cutter to produce a semiconductor wafer protective film. This semiconductor wafer protection film has a planar size of 1.5 mm for the convex and concave portions. 2 The density of the convex and concave portions is 4 / cm 2 The flat area ratio was 90%, the surface roughness Ra was 0.15 μm, and the L value was 1.1.

[0023] [Example 2] A semiconductor wafer protective film was produced in the same manner as in Example 1, except that antistatic agent 1 was changed to antistatic agent 2.

[0024] [Comparative Example 1] A semiconductor wafer protective film was produced in the same manner as in Example 1, except that the synthetic resin film deposition temperature was 165° C. and the surface roughness Ra of the semiconductor wafer protective film was 0.08 μm.

[0025] Comparative Example 2 A semiconductor wafer protection film was produced in the same manner as in Example 1, except that the synthetic resin film was wound around a matte roll during film formation and the surface roughness Ra of the semiconductor wafer protection film was 1.0 μm.

[0026] The semiconductor wafer protection films obtained in each of the Examples and Comparative Examples were evaluated for the following items. The results are shown in Table 1.

[0027] [Defect ratio] One thousand of the obtained semiconductor wafer protective films were randomly picked up, and the presence or absence of foreign matter or fisheyes exceeding 0.2 mm was checked using a defect detector (CA-HL08MX, manufactured by Keyence Corporation), and the results were evaluated according to the following criteria. ○ Less than 1% of the items have foreign matter or fish eyes ×: 1% or more of the items have foreign matter or fish eyes

[0028] [Defect detection accuracy] The obtained semiconductor wafer protective films were visually inspected for defects at a rate of one film per second, and 1,000 films were randomly selected from those judged to be non-defective. They were checked for the presence or absence of foreign matter or fisheyes exceeding 0.2 mm using a defect detector (CA-HL08MX, manufactured by Keyence Corporation), and evaluated according to the following criteria. ○: Fewer than 0.3% have foreign matter or fish eyes ×: More than 0.3% of the products contain foreign matter or fish eyes.

[0029] [Corrosive] The obtained semiconductor wafer protection film was placed between 8-inch aluminum-deposited wafers, placed in a container at a pressure of 5 KPa, and stored in a high-temperature, high-humidity (40°C x 90% RH) environment for 7 days. The aluminum-deposited wafer surfaces were then observed with a microscope to evaluate whether or not corrosion had occurred. ○ No corrosion △: Slight corrosion

[0030] [Table 1] [Explanation of symbols]

[0031] 1. Semiconductor wafer protection film 2. Semiconductor wafers 3. Cushioning material 4 Container body 5 Container lid 6. Semiconductor wafer transport container 7 Flat area 8 Convex part 9 Recess

Claims

1. A semiconductor wafer protection film having a corrugated cross section in which convex portions and concave portions are alternately arranged, The convex and concave portions are each 1 cm ２ There are 1 to 16 of them formed around The size of the convex and concave portions in plan view is 0.3 to 5.0 mm ２ and A semiconductor wafer protection film having a surface roughness Ra of 0.1 to 0.4 μm.

2. 2. The semiconductor wafer protection film according to claim 1, further comprising a flat portion between the convex portion and the concave portion.

3. 3. The semiconductor wafer protection film according to claim 1, wherein the L value is less than 30.

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