JP7782130B2 - Package of electrode plate for plasma etcher and packaging method for the package of electrode plate for plasma etcher - Google Patents

Description

The present invention relates to a package containing mirror-finished objects, such as electrode plates for plasma etchers and sputtering targets for semiconductors, which require high levels of cleanliness, and a packaging method for the package of mirror-finished objects.

Electrode plates for plasma etchers are known. Such electrode plates can cause problems if used with foreign matter adhering to the mirror-finished surface (mirror-finished surface). Therefore, the mirror-finished surface is cleaned to remove the foreign matter before use. To prevent such foreign matter from adhering, for example, the mirror-finished object is transported sealed in a vacuum bag. However, transporting the mirror-finished object sealed in a vacuum bag still does not prevent the generation of foreign matter, so further solutions are being sought.

For example, although the technical field is different, the following efforts have been made in the field of semiconductor wafers (hereinafter referred to as wafers) having mirror-finished surfaces.
To handle these wafers, multiple wafers were placed in a single plastic container, and multiple such containers were packed in a box with cushioning material between each container, and then the box was transported. This made the packaging process complicated and required multiple storage containers, which was costly and wasteful. Furthermore, when unpacking the wafers, a cleaning process with ultrapure water was required to remove dust that had accumulated during these processes and contaminants that had accumulated inside the container.

To overcome these difficulties, known packaging methods include stacking semiconductor wafers and ice sheets made from ultrapure water (DIW) ice alternately and storing them in a container, as well as the methods described in Patent Documents 1 and 2. The method described in Patent Document 1 proposes a packaging method in which multiple semiconductor wafers are frozen in ultrapure water (pure water that has been subjected to ion exchange and filtering, and then further purified using methods such as reverse osmosis) while spaced at a predetermined distance from one another, and then stored in a container. Furthermore, the method described in Patent Document 2 involves coating the entire surface of mirror-polished semiconductor wafers with polyethylene glycol wax.

Japanese Patent Application Publication No. 4-128173 Japanese Patent Application Publication No. 6-204315

The methods described in Patent Documents 1 and 2 above involve complicated packaging methods and are not easy to unpack, so the general practice for packaging mirror-finished objects is to pack them in a vacuum-sealed bag. However, if the bag is made of resin film, tiny foreign matter such as stains, cloudiness, and white particles will be visible on the mirror-finished surface when the packaged object is opened. For this reason, there is a demand for a packaging method for mirror-finished objects that can prevent tiny foreign matter from appearing on the mirror-finished surface of the mirror-finished object, even when using a simple packaging method such as packaging in resin film.

The present invention was made in consideration of these circumstances, and aims to provide a package for a mirror-finished object and a packaging method for a mirror-finished object that can prevent the occurrence of minute foreign matter on the mirror-finished surface of the mirror-finished object.

The packaged product of the present invention for a mirror-finished object is a packaged product in which a mirror-finished object having a mirror-finished surface is sealed in a bag made of resin film under a vacuum, the mirror-finished surface being in contact with the resin film that constitutes the bag, and the crystallinity of the resin film is 40% or more and 60% or less.

If the crystallinity of the resin film of the present invention is less than 40%, the resin film in contact with the mirror-finished surface will be too soft, and amorphous molecules (for example, PE molecules if the resin film is made of polyethylene) will adhere to the mirror-finished surface and become micro-foreign matter. On the other hand, if the crystallinity of the resin film exceeds 60%, the resin film in contact with the mirror-finished surface will become hard and brittle, and when it comes into contact with the resin film when storing a mirror-finished object inside the bag, a portion of it will peel off and become micro-foreign matter. In contrast, in the present invention, the crystallinity of the resin film is set within an appropriate range of 40% to 60%, which prevents the generation of micro-foreign matter originating from the resin film in contact with the mirror-finished surface of the mirror-finished object.

In a preferred embodiment of the packaging for mirror-finished products of the present invention, the crystallinity of the resin film is 44% or more and 54% or less.

The packaged product for a mirror-finished object of the present invention is a packaged product in which a mirror-finished object having a mirror-finished surface is sealed in a bag under vacuum, with an inner resin film covering the mirror-finished surface disposed between the mirror-finished surface and the inner surface of the bag, and the peripheral portion of the inner resin film being positioned so as to extend beyond the peripheral edge of the mirror-finished object.

In this invention, when a mirror-finished object with its mirror-finished surface covered with an inner resin film is stored in a bag, the peripheral edge of the inner resin film is positioned to extend beyond the peripheral edge of the mirror-finished object, preventing the edge of the mirror-finished object from coming into direct contact with the bag and generating minute foreign matter. Furthermore, because the mirror-finished object is protected by a two-layer structure consisting of the bag and the inner resin film, the mirror-finished object can be more reliably protected.

In a preferred embodiment of the mirror-finished package of the present invention, the first coefficient of friction between the surface of the inner resin film facing the bag body and the inner surface of the bag body is smaller than the second coefficient of friction between the mirror-finished surface and the surface of the inner resin film that comes into contact with the mirror-finished surface.

In the above-described embodiment, since the second friction coefficient is greater than the first friction coefficient, when a mirror-finished object whose mirror-finished surface is covered with an inner resin film is placed in a bag and when the bag is evacuated, relative movement does not occur between the mirror-finished surface and the inner resin film, but occurs between the inner resin film and the inner surface of the bag. In other words, since there is no rubbing between the mirror-finished object and the inner resin film, the generation of minute foreign matter caused by rubbing between the mirror-finished object and the inner resin film can be suppressed.
Furthermore, if the first friction coefficient is greater than the second friction coefficient, the inner resin film and the inner surface of the bag body will be in close contact with each other when the bag is stored or evacuated, which may cause a misalignment between the mirror-finished body and the inner resin film, resulting in the mirror-finished surface rubbing against the inner resin film and the generation of tiny foreign matter.

In a preferred embodiment of the package of mirror-finished objects of the present invention, the second friction coefficient/first friction coefficient is 1.2 or more.
In the above embodiment, the inner resin film and the bag body are more easily slippery than the inner resin film and the mirror-finished surface, so that the generation of minute foreign matter caused by friction between the mirror-finished body and the inner resin film during storage or vacuuming can be reliably suppressed.

In a preferred embodiment of the package of mirror-finished products of the present invention, the crystallinity of the inner resin film is 40% or more and 60% or less.
In the above embodiment, the crystallinity of the inner resin film is set to an appropriate range of 40% or more and 60% or less, thereby preventing the generation of minute foreign matter originating from the inner resin film that comes into contact with the mirror-finished surface of the mirror-finished body.

The packaging method for a packaged mirror-finished object of the present invention involves placing a mirror-finished object having a mirror-finished surface inside a bag made of a resin film with a crystallinity of 40% to 60%, and then vacuum sealing the bag with the resin film constituting the bag in contact with the mirror-finished surface.

The packaging method for a packaged mirror-finished object of the present invention involves enclosing a mirror-finished object having a mirror-finished surface in a bag with the mirror-finished surface covered with an inner resin film and sealing the bag.

This invention provides a simple method for preventing minute foreign particles from appearing on the mirror-finished surface of a mirror-finished object.

1 is a plan view showing a package of mirror-finished objects according to a first embodiment of the present invention; FIG. 2 is a perspective view showing the mirror-finished body of the first embodiment. 3 is a schematic diagram showing a packaging method for the mirror-finished body of the first embodiment. FIG. FIG. 10 is a plan view showing a package of mirror-finished objects according to a second embodiment of the present invention. 10 is a schematic diagram showing the arrangement of an inner resin film in the packaging method for the mirror-finished body according to the second embodiment. FIG. 10 is a schematic diagram showing how a mirror-finished body sandwiched between inner resin films is stored in a bag body in the packaging method for a mirror-finished body according to the second embodiment. FIG. 1 is an image showing the rubbing range of a silicon plate when a resin film 2 is rubbed on top of a resin film 1. 1 is an image showing the above-mentioned area of a silicon plate onto which a resin film 2 is rubbed without using a resin film 1. FIG. 10 is a diagram showing detection conditions for smudges and particles.

Each embodiment of the package for a mirror-finished object and the packaging method for the package for a mirror-finished object of the present invention will be described below with reference to the drawings.

[First embodiment]
As shown in Fig. 1, a package 30 for a mirror-finished body 10 of this embodiment (hereinafter referred to as package 30) is a package in which the mirror-finished body 10 having a mirror-finished surface 11 is sealed in a bag 20 made of resin film under a vacuum. This mirror-finished body 10 is an electrode plate for a plasma etcher made of, for example, Si (silicon), an intermetallic compound, or ceramics, and is formed in a disk shape as shown in Fig. 2. The mirror-finished surface 11 is formed on both the front and back sides of the mirror-finished body 10.
For example, the diameter of the mirror-finished body 10 is 203 mm to 530 mm, the thickness is 3 mm to 19 mm, and the arithmetic mean roughness Ra of the mirror-finished surface 11 is 0.01 to 0.2.

As shown in Fig. 1, the bag 20 is formed larger than the mirror-finished surface 11 of the mirror-finished body 10 in a plan view, and seals the mirror-finished body 10 inside. The resin film constituting the bag 20 is made of, for example, polyethylene. In this case, it is preferable to use an additive-free resin that does not contain additives such as antioxidants or lubricants. The resin film constituting the bag 20 is formed into a film shape by inflation molding or the like.
For example, the bag body 20 has a planar size of 100 mm to 700 mm x 150 mm to 800 mm and a thickness of 70 μm to 130 μm.

The crystallinity of the resin film constituting the bag body 20 is set to 40% or more and 60% or less. This crystallinity is the proportion of crystalline portions and is also a measure of the physical properties of the resin film, such as mechanical strength, density, heat resistance, and transparency. In this embodiment, the crystallinity of the resin film constituting the bag body 20 is set to an appropriate range of 40% or more and 60% or less. This crystallinity is preferably 44% or more and 54% or less. Furthermore, the crystallinity of this resin film is more preferably 45% or more and 51% or less.
If the crystallinity of the resin film constituting the bag body 20 is less than 40%, the resin film that comes into contact with the mirror-finished surface 11 will be too soft, and amorphous PE molecules will stick to the mirror-finished surface 11 and become minute foreign matter. On the other hand, if the crystallinity of the resin film exceeds 60%, the resin film will be hard and brittle, and when rubbed, parts will peel off and become minute foreign matter.

[Packaging method for mirror-finished product]
The package 30 of the mirror-finished object 10 is packaged by preparing a bag 20 made of a resin film with a crystallinity of 40% to 60%, and placing and sealing the mirror-finished object 10 inside the bag 20. Specifically, as shown in FIG. 3 , the bag 20 is opened and the mirror-finished object 10 is placed inside the bag 20. If the edge of the mirror-finished object 10 comes into contact with the inner surface of the bag 20, there is a possibility of generating minute foreign matter. Therefore, the mirror-finished object 10 is placed inside the bag 20 so as to avoid contact with the inner surface of the bag 20 as much as possible. Then, the air inside the bag 20 is evacuated using a vacuum packaging device, and the bag 20 is sealed to create a hermetic state. The mirror-finished object 10 is thus packaged in the bag 20, forming the package 30 of the mirror-finished object 10.

In the packaging body 30 of this embodiment, the crystallinity of the resin film forming the bag body 20 is set to an appropriate range of 40% to 60%, which can prevent the generation of minute foreign matter originating from the resin film that comes into contact with the mirror-finished surface 11 of the mirror-finished body 10. Furthermore, in the packaging body 30 of this embodiment, the generation of minute foreign matter can be prevented simply by adjusting the crystallinity of the resin film forming the bag body 20, thereby reducing packaging costs.
For example, when the mirror-finished object 10 is an electrode plate or a sputtering target for a plasma etcher, it is typically removed from a bag, placed in a vacuum chamber, evacuated, and then a voltage is applied to the mirror-finished object 10 to generate plasma. If minute foreign matter adheres to the mirror-finished surface 11, this minute foreign matter will cause an abnormal discharge to occur, scattering the foreign matter onto the processing substrate in the plasma etcher or onto the deposition substrate in the sputtering target. In contrast, this embodiment can prevent minute foreign matter from being generated on the mirror-finished surface 11 of the mirror-finished object 10, thereby suppressing abnormal discharge originating from the minute foreign matter in subsequent processes and preventing foreign matter from scattering onto the processing substrate or deposition substrate.

Second Embodiment
Next, a package of a mirror-finished product according to a second embodiment will be described with reference to the drawings. In the following description, the same or substantially the same components as those in the first embodiment will be denoted by the same reference numerals, and the description will be omitted or simplified.
The packaging body 31 (hereinafter referred to as packaging body 31) for the mirror-finished body 10 of this embodiment is a packaging body in which the mirror-finished body 10 having a mirror-finished surface 11 is sealed in a bag body 21 under vacuum, as shown in Figure 4, and an inner resin film 40 is provided between the mirror-finished surface 11 of the mirror-finished body 10 and the bag body 21.

As shown in FIG. 4, the bag body 21 is formed larger than the mirror-finished surface 11 of the mirror-finished body 10 and the inner resin film 40 in a plan view, and seals the mirror-finished body 10 and inner resin film 40 inside. In this embodiment, since the inner resin film 40 is provided, the bag body 21 may be formed from a resin film such as polyethylene, as in the first embodiment, or from other materials. The bag body 21 has, for example, a planar size of 100 mm to 700 mm x 150 mm to 800 mm and a thickness of 70 μm to 130 μm.

As shown in FIG. 4, the inner resin film 40 housed in the bag 21 together with the mirror-finished body 10 is formed in a circular shape that is slightly larger than the mirror-finished surface 11 of the mirror-finished body 10 in a plan view, and covers the entire area of the mirror-finished surface 11 of the mirror-finished body 10. Furthermore, because the bag 21 is sealed under a vacuum, the inner resin film 40 is disposed within the bag 21 in contact with both the mirror-finished surface 11 and the inner surface of the bag 21. This inner resin film 40 is preferably made of the same material as the bag 21 (e.g., polypropylene), and is preferably an additive-free resin that does not contain additives such as antioxidants or lubricants. Furthermore, the inner resin film 40 is formed into a film by inflation molding or the like.

The diameter of the inner resin film 40 is slightly larger than the diameter of the mirror-finished body 10, which is 203 mm to 530 mm, and is set to, for example, 204.5 mm to 539.5 mm, with a thickness of 70 μm to 130 μm. In this embodiment, the inner resin film 40 is shaped to cover the entire area of the mirror-finished surface 11. To prevent the edge of the mirror-finished body 10 from contacting the bag body when storing the mirror-finished body 10 inside the bag body 21, the inner resin film 40 must be formed larger than the diameter of the mirror-finished surface 11 and positioned so that the peripheral edge of the inner resin film 40 extends beyond the peripheral edge of the mirror-finished body 10. On the other hand, if the peripheral edge of the inner resin film 40 extends significantly beyond the peripheral edge of the mirror-finished body 10, wrinkles may form near the edge of the mirror-finished body 10 when sealed in a vacuum, potentially causing friction with the edge of the mirror-finished body 10 or the inner surface of the bag body 21. For this reason, it is preferable that the amount of protrusion of the inner resin film 40 from the peripheral edge of the mirror-finished surface 11 be smaller than the thickness of the mirror-finished body 10, for example, less than half the thickness of the mirror-finished body 10.

The crystallinity of the inner resin film 40 is set to 40% or more and 60% or less. This prevents minute foreign matter from being generated from the resin film in contact with the mirror-finished surface 11 of the mirror-finished body 10. The crystallinity is preferably 44% or more and 54% or less. The crystallinity is more preferably 45% or more and 51% or less.
If the crystallinity of the inner resin film 40 is less than 40%, the inner resin film 40 in contact with the mirror-finished surface 11 will be too soft, and amorphous PE molecules may adhere to the mirror-finished surface 11 and become minute foreign matter. On the other hand, if the crystallinity of the inner resin film 40 is more than 60%, the inner resin film 40 will be hard and brittle, and there is a possibility that parts of the inner resin film 40 will peel off and become minute foreign matter.

Furthermore, the first coefficient of friction between the surface of the inner resin film 40 facing the bag body 21 (the outer surface of the inner resin film 40) and the inner surface of the bag body 21 is smaller than the second coefficient of friction between the mirror-finished surface 11 and the surface of the inner resin film 40 that contacts the mirror-finished surface 11. The ratio of the second friction coefficient to the first friction coefficient, i.e., second friction coefficient/first friction coefficient (the value obtained by dividing the second friction coefficient by the first friction coefficient), is preferably 1.2 or greater. By making the second friction coefficient larger than the first friction coefficient, relative movement between the mirror-finished surface 11 and the inner resin film 40 is suppressed when the mirror-finished body 10, whose mirror-finished surface 11 is covered with the inner resin film 40, is placed in the bag body 21, or when the bag body 21 is evacuated, thereby allowing relative movement between the inner resin film 40 and the inner surface of the bag body 21. In other words, rubbing between the mirror-finished body 10 and the inner resin film 40 is suppressed. Furthermore, the second friction coefficient/first friction coefficient is more preferably 1.3 or more, and even more preferably 1.5 or more.

[Packaging method for mirror-finished product]
The package 21 of the mirror-finished body 10 is packaged by enclosing the mirror-finished body 10 in a state where the entire area of the mirror-finished body 10 is covered with the inner resin film 40, and then sealing the same in the bag 21. This will be described in detail below.
First, as shown in Fig. 5, two inner films 40 are brought into contact with the front and back mirror-finished surfaces 11 of the mirror-finished body 10 so as to cover the entire area of each mirror-finished surface 11 of the mirror-finished body 10. At this time, the inner resin films 40 are arranged so that the peripheral portion of the inner resin films 40 extends beyond the peripheral edge of the mirror-finished body 10 so that the edge of the mirror-finished body 10 does not extend outside the inner resin films 40. Then, as shown in Fig. 6, the mirror-finished body 10, whose entire area is covered by the inner resin films 40, is stored in the bag 21.
Then, the air inside the bag 21 is evacuated, and the bag 21 is sealed by pressing a heated heater rod against the open end of the bag 21 and welding it, etc. In this way, the mirror-finished body 10 is packaged in the bag 21, and a package 31 of the mirror-finished body 10 is formed.

In this embodiment, the bag 21 is evacuated with the mirror-finished surface 11, inner resin film 40, and bag 21 stacked in this order. Therefore, if the first coefficient of friction between the surface of the inner resin film 40 facing the bag 21 (the surface of the inner resin film 40 facing the inner surface of the bag 21) and the inner surface of the bag 21 is greater than the second coefficient of friction between the mirror-finished surface 11 and the surface of the inner resin film 40 that comes into contact with the mirror-finished surface 11, the inner resin film 40 and the inner surface of the bag 21 will come into close contact with each other during evacuation, causing misalignment between the mirror-finished body 10 and the inner film 40, which may result in the generation of minute foreign matter due to friction between the mirror-finished surface 11 and the inner resin film 40.

For this reason, in this embodiment, the first coefficient of friction between the surface of the inner resin film 40 facing the bag body 21 and the inner surface of the bag body 21 is set to be smaller than the second coefficient of friction between the mirror-finished surface 11 and the surface of the inner resin film 40 that comes into contact with the mirror-finished surface 11. Because the second coefficient of friction is larger than the first coefficient of friction, when the mirror-finished body 10, whose mirror-finished surface 11 is covered with the inner resin film 40, is placed in the bag body 21, and when the bag body 21 is evacuated, relative movement does not occur between the mirror-finished surface 11 and the inner resin film 40, but occurs between the inner resin film 40 and the inner surface of the bag body 21. In other words, there is no rubbing between the mirror-finished body 10 and the inner resin film 40, and therefore the generation of minute foreign matter caused by rubbing between the mirror-finished body 10 and the inner resin film 40 can be suppressed.
The ratio of the second friction coefficient to the first friction coefficient is preferably 1.2 or more. In this case, the inner resin film 40 and the inner surface of the bag body 21 slide more easily than the inner resin film 40 and the mirror-finished surface 11, so that the generation of minute foreign matter caused by rubbing between the mirror-finished body 10 and the inner resin film 40 during storage or evacuation can be reliably suppressed.

In this embodiment, when the mirror-finished body 10, whose mirror-finished surface 11 is covered with the inner resin film 40, is stored in the bag 21, the peripheral edge of the inner resin film 40 is positioned so that it extends beyond the peripheral edge of the mirror-finished body 10, thereby preventing the edge of the mirror-finished body 10 from coming into direct contact with the bag 21 and generating minute foreign matter. Furthermore, by positioning the inner resin film 40 between the mirror-finished body 10 and the bag 21, the mirror-finished body 10 is protected by a two-layer structure consisting of the bag 21 and the inner resin film 40, thereby more reliably protecting the mirror-finished body 10. Furthermore, because the crystallinity of the inner resin film 40 is set within an appropriate range of 40% to 60%, the generation of minute foreign matter originating from the inner resin film 40 that comes into contact with the mirror-finished surface 11 of the mirror-finished body 10 is prevented.

The present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made to the detailed configurations without departing from the spirit of the present invention.
For example, in the second embodiment, the inner resin film 40 has a circular shape in a plan view, but is not limited to this, and may have, for example, a rectangular shape.

In the second embodiment described above, the inner resin film 40 is shaped to cover the entire area of the mirror-finished surface 11, but this is not limited thereto. For example, the inner resin film may have multiple holes formed in the center, or may have a shape that does not necessarily cover the entire area. Furthermore, the inner resin film 40 may be shaped to cover an area that includes at least the periphery of the mirror-finished surface 11 (for example, a shape that covers only the periphery of the mirror-finished surface).

In the second embodiment described above, the bag body 21 may be made of any material, but this is not a limitation. For example, the bag body 21 may be made of the same material as the inner resin film 40. In this case, even if the inner resin film 40 is damaged and the resin film constituting the bag body comes into contact with a mirror-finished body, the crystallinity of both the inner resin film 40 and the resin film constituting the bag body will be within the above-mentioned range, so even if the inner resin film 40 is damaged, the generation of minute foreign matter can be suppressed. Furthermore, using the same material reduces manufacturing costs.

A 380mm diameter, 10mm thick silicon disk (silicon plate), a 700mm x 800mm polyethylene bag to house the silicon plate, and a 390mm diameter, 100μm thick polyethylene inner resin film (samples A, B, C) covering the entire mirror-finished surface of the silicon plate were prepared. The crystallinity of each of samples A, B, and C was measured, as well as the static and dynamic friction coefficients between the inner resin film of each of samples A, B, and C and the silicon plate and the inner surface of the bag.

(Method for measuring crystallinity)
The crystallinity of each sample A, B, and C was measured by XRD (X-ray diffraction). This measurement was performed using a Bruker X-ray analyzer (D8 Discover) at six arbitrary points (n = 6) on the mirror-finished surface (front and back) of the silicon plate to determine the crystalline scattering intensity and non-crystalline scattering intensity. These values were used to calculate the crystallinity (average value of the six points). The results are shown in Table 1.
In this example, the crystallinity was calculated based on the following formula 1.
Crystallinity Xc=Ic/(Ic+Ia)×100...(Formula 1)
Ic: Crystalline scattering intensity, Ia: Amorphous scattering intensity

(Method for measuring static and dynamic friction coefficients)
The static and dynamic friction coefficients were measured as follows.
The first friction coefficient was measured by fixing a polyethylene bag to be measured to the test equipment, attaching samples A, B, and C to the indenter, and placing the indenter with samples A, B, and C attached on the bag fixed to the test equipment. The static and kinetic friction coefficients were measured by applying a constant load to the indenter and moving it at a constant speed for a constant distance. The second friction coefficient was measured by fixing a silicon plate to be measured to the test equipment, attaching samples A, B, and C to the indenter, and placing the indenter with samples A, B, and C attached on the silicon plate fixed to the test equipment. The static and kinetic friction coefficients were measured by applying a constant load to the indenter and moving it at a constant speed for a constant distance. Specifically, the test was performed three times for each sample under the following test conditions, and the average and standard deviation were calculated. The static friction coefficient test results are shown in Table 2, and the kinetic friction coefficient test results are shown in Table 3.
[Test conditions]
Equipment used: Tribogear Type 40 (Shinto Chemical)
Speed: 1000mm/m
Distance: 30mm
Indenter used: φ12 mm steel wool holder load: 200 g

As shown in Table 2, for the static friction coefficients, the first friction coefficient was smaller than the second friction coefficient for all of Samples A, B, and C, and the ratio of the second friction coefficient to the first friction coefficient was 1.4 or greater. Furthermore, as shown in Table 3, for the kinetic friction coefficients, the first friction coefficient was smaller than the second friction coefficient for all of Samples A, B, and C, and the ratio of the second friction coefficient to the first friction coefficient was 1.7 or greater. Thus, for both the static and kinetic friction coefficients, the first friction coefficient was smaller than the second friction coefficient for all of the samples. This shows that by covering the mirror-finished surface of the silicon plate with the inner resin film, no relative movement occurs between the mirror-finished surface and the inner resin film when the silicon plate is placed in the bag and when the bag is evacuated, but relative movement occurs between the inner resin film and the inner surface of the bag.

In addition, resin film 1 (for example, sample A) was placed on the mirror-finished surface of a silicon plate, and resin film 2 (sample A) was rubbed five times over a 3 cm x 3 cm area of the silicon plate on top of resin film 1 (sample A), and the mirror-finished surface was directly rubbed five times with resin film 2 (sample A) over the same area, without resin film 1 (sample A), and the occurrence of micro-foreign matter was visually confirmed.
The results are shown in Figures 7 and 8. Figure 7 is an image showing the rubbing area of the silicon plate when resin film 1 (sample A) was used, and Figure 8 is an image showing the same area of the silicon plate when resin film 2 was rubbed without using resin film 1 (sample A).

In an experiment in which resin film 1 (sample A) was placed on a silicon plate and then rubbed with resin film 2, the results showed that, for example, as shown in Figure 7, no minute foreign matter was generated due to rubbing between resin film 1 and the silicon plate. On the other hand, when resin film 2 was rubbed directly against the silicon plate without resin film 1 (sample A), minute foreign matter was generated due to rubbing between the silicon plate and resin film 2, as shown in Figure 8. In other words, it was found that simply providing an inner resin film can suppress the generation of minute foreign matter caused by rubbing of the resin film. Based on these findings, the experiment shown in the following first example was conducted.

[First Example]
The above-described silicon disks and bags with a planar size of 700 mm x 800 mm were fabricated. The bags were made from the resin films of Samples A, B, and C, each with a different degree of crystallinity. The resin films of Samples A, B, and C were also fabricated as inner resin films. Silicon plates coated with the inner resin films of Samples A, B, and C were then housed in the bags fabricated from Samples A, B, and C, respectively, and vacuum-sealed to produce Samples No. 1 to No. 9. Each sample was then unpacked, and the mirror-finished surfaces (both sides) of the silicon plates were observed. The number of smudges and particles, which are minute foreign matter, was measured and evaluated. Smudges are defined as white, cloudy stains (approximately 1 μm or larger) that can be visually observed when illuminated from various angles in a darkroom at distances of 1 cm, 3 cm, and 5 cm from an LED light with an output of 1000 lumens or more. Furthermore, particles are point-like foreign objects (approximately 1 μm or larger) that can be visually observed when an LED light of 300 lumens or more is placed in a dark room at distances of 1 cm, 3 cm, and 5 cm and illuminated from various angles.

(Method for evaluating the occurrence of minute foreign matter)
Each sample was vacuum-sealed by placing a silicon plate coated with an inner resin film made of each sample A, B, or C in a bag manufactured for each sample A, B, or C. The samples were then unpacked, and the mirror-finished surfaces (both sides) of the silicon plate were observed to measure the number of smudges and particles, which are minute foreign bodies. Smudges were measured in a darkroom at distances of 1, 3, and 5 cm from a 1,000-lumen LED light bulb, with angles α of 30°, 45°, and 80° and angles β of 0°, 60°, 120°, 180°, 240°, and 320°, as shown in Figure 9. Particle counts were measured in a darkroom at distances of 1, 3, and 5 cm from a 300-lumen LED light bulb, with angles α of 30°, 45°, and 80° and angles β of 0°, 60°, 120°, 180°, 240°, and 320°, as shown in Figure 9. That is, since there are three different LED distances, three different angles α, and six different angles β, the number of smudges and particles generated was measured under a total of 54 conditions (108 conditions when the front and back are combined). Note that the locations where smudges or particles were detected in the following evaluation are the total number of locations where smudges or particles were generated, detected under all 108 conditions when the distance and angles α and β were changed.
The evaluation criteria were based on whether smudges or particles were present, with "absent" being the case when no smudges or particles were found, "very small amounts" being the case when they were found in 1 to 3 locations, "few amounts" being the case when they were found in 4 to 9 locations, and "large amounts" being the case when they were found in 10 or more locations. A sample with no smudges or particles, or a sample with only a small amount of one and no other, was judged as passing, while any other sample was judged as failing. The results are shown in Table 4. The crystallinity and friction coefficient ratio (second friction coefficient/first friction coefficient) of the inner film were detected by the methods described above.

As shown in Table 4, when the bag body was manufactured using Sample A, B, or C, and the inner film was manufactured using Sample A, B, or C, the generation of smudges and particles was virtually eliminated. Furthermore, since Sample No. 7 had the smallest second friction coefficient/first friction coefficient (friction coefficient ratio) of 1.2, it is believed that only a very small amount of smudge was generated.

[Second Example]
The silicon plate and bag body with a planar size of 700 mm x 800 mm shown in Example 1 were fabricated. The bag body material was made from resin films of Samples A, B, C, D, E, and F, each with a different degree of crystallinity, and bags were manufactured using these samples. Then, a silicon plate was placed in the bag body manufactured for each of Samples A, B, C, D, E, and F and vacuum-sealed to produce Samples No. 10 to No. 15. Next, each of these samples was unpacked, and the mirror-finished surfaces (both sides) of the silicon plate were observed. The number of smudges and particles, which are minute foreign matter, was measured and evaluated. The detection and evaluation methods for smudges and particles were performed in the same manner as in Example 1 above. Samples A, B, and C were made from the same material as Samples A, B, and C in Example 1 above. Sample D had a high crystallinity of 63%, and Sample E had a low crystallinity of 35%. Sample F was also formulated with an additive. The crystallinity of each sample was measured by the method described above.

As shown in Table 5, sample No. 15 was judged to be unacceptable overall without even measuring the crystallinity because the resin film of sample F contained additives and had an extremely low degree of crystallinity, resulting in the generation of large amounts of both smudges and particles. Sample No. 10 was judged to be unacceptable overall because the resin film of sample D had a high degree of crystallinity of 63%, resulting in the generation of small amounts of particles. Sample No. 14 was judged to be unacceptable overall because the resin film of sample E had a low degree of crystallinity of 35%, resulting in the generation of small amounts of smudges.
As described above, a resin film with a crystallinity of 43% to 58% was deemed acceptable. Taking the results of these samples together, it appears that in order to suppress the generation of minute foreign matter due to the resin film, a resin film constituting the bag with a crystallinity of 40% to 60% and containing no additives is suitable for use. Among these, sample No. 12 showed no smudge or particle generation, indicating that a crystallinity of 48 (σ=3), i.e., 45% to 51%, is more preferable.

10 Mirror-finished body 11 Mirror-finished surfaces 20, 21 Bag body 30, 31 Package body of mirror-finished body 40 Inner resin film

Claims (3)

A package in which an electrode plate for a plasma etcher having a mirror-finished surface is sealed in a bag under vacuum, an inner resin film covering the mirror-finished surface is provided between the electrode plate for the plasma etcher and the inner surface of the bag, and a peripheral portion of the inner resin film is arranged so as to protrude beyond the peripheral edge of the electrode plate for the plasma etcher,
the inner resin film is made of additive-free polyethylene, and its crystallinity is 40% or more and 60% or less;
A packaging body for electrode plates for plasma etchers, characterized in that a first coefficient of friction between the surface of the inner resin film facing the bag body and the inner surface of the bag body is smaller than a second coefficient of friction between the mirror-finished surface and the surface of the inner resin film that comes into contact with the mirror-finished surface. 2. The package of electrode plates for a plasma etcher according to claim 1 , wherein the second friction coefficient/the first friction coefficient is 1.2 or more. A packaging method for a plasma etcher electrode plate having a mirror-finished surface, in which the mirror-finished surface is covered with an inner resin film made of additive-free polyethylene with a crystallinity of 40% to 60% and the plate is then placed in a bag and sealed, wherein a first coefficient of friction between the surface of the inner resin film facing the bag and the inner surface of the bag is smaller than a second coefficient of friction between the mirror-finished surface and the surface of the inner resin film that comes into contact with the mirror-finished surface.