Mirror-finished body

Abstract

To prevent attachment of microscopic foreign substances to a mirror-finished surface of a mirror-finished body.SOLUTION: At least one face of a mirror-finished body is formed of a mirror-finished surface having an arithmetic average roughness Ra of 0.2 μm or less. When a light source is installed in a darkroom such that the mirror-finished surface has an illuminance of 30000 lux or more and 60000 lux or less, and a surface of the mirror-finished surface is observed by using the light source, the number of microscopic foreign substances having a circumscribed circle diameter of 1 μm or more is 5 or less on the entire surface of one mirror-finished surface. The mirror-finished body is made of silicon.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a mirror-finished body such as an electrode plate for a plasma etcher or a sputtering target for a semiconductor, which requires high cleanliness. [Background technology]

[0002] Conventionally, an electrode plate for a plasma etcher is known. When such an electrode plate is used with foreign matter adhering to the mirror surface (mirror-finished surface) that has been mirror-finished, a malfunction occurs, so the mirror-finished surface is cleaned to remove the foreign matter before use. In order to prevent such adhesion of foreign matter, for example, the mirror-finished body is sealed in a vacuum state in a bag and transported. However, even if the mirror-finished body is transported in a vacuum-sealed state, the generation of foreign matter cannot still be prevented, so further solutions are being sought.

[0003] For example, although in different technical fields, the methods described in Patent Documents 1 and 2 are known as methods for packaging glass substrates for magnetic disks having a mirror-finished surface. In the manufacturing method of a glass substrate for a magnetic disk described in Patent Document 1, one or more glass substrates for a magnetic disk are housed in a case, the case is housed in a packaging bag, the inside of the packaging bag is degassed by reducing the pressure therein at a degassing rate of 0.1 MPa / sec or less, and the opening of the packaging bag is sealed in the degassed state. Moreover, the package for glass substrates for magnetic disks in Patent Document 2 includes a case for housing one or more glass substrates for magnetic disks, a first light-blocking packaging bag made of a metal laminate film that seals the case in a deaerated state, and a second packaging bag made of a plastic film that seals the first packaging bag from the outside in a deaerated state. That is, in the configurations of Patent Documents 1 and 2, the magnetic disk glass substrate is placed in a packaging bag, which is then sealed in a deaerated state to form a package of the magnetic disk glass substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5234741 [Patent Document 2] Patent No. 5377849 Summary of the Invention [Problem to be solved by the invention]

[0005] The methods described in Patent Documents 1 and 2 above involve placing a mirror-finished body in a packaging bag and then sealing it, so that minute foreign matter generated from the end of the bag may adhere to the mirror-finished surface when the mirror-finished body is inserted into the packaging bag, leaving a line mark visible to the naked eye on the mirror-finished surface. For this reason, there is a demand for a packaging method for mirror-finished bodies that can prevent minute foreign matter from adhering to the mirror-finished surface of the mirror-finished body even when the packaging method is simple, such as packaging the mirror-finished body in a packaging bag made of resin film or the like.

[0006] The present invention has been made in view of the above circumstances, and has an object to suppress adhesion of minute foreign matter to the mirror-finished surface of a mirror-finished body. [Means for solving the problem]

[0007] In the present invention, the method for packaging a mirror-finished body includes placing the mirror-finished body on a resin film, placing a part of the resin film or a resin film different from the resin film on the mirror-finished body, and sealing the entire periphery of the overlapping portion between the resin film located on the lower side of the mirror-finished body and the resin film located on the upper side while evacuating the internal air.

[0008] In this packaging method, the resin film is folded over and a portion of it is placed over the mirror-finished body located on the resin film, and the entire periphery of the portion where the upper resin film and the lower resin film overlap, excluding the folded portion, is joined, or a different resin film is placed over the mirror-finished body, and the entire periphery of the portion where the upper resin film and the lower resin film overlap is joined, thereby making it possible to house the mirror-finished body in a bag-shaped resin film. This prevents minute foreign matter from being generated when the mirror-finished body is housed in a bag-shaped resin film, making it possible to prevent minute foreign matter from adhering to the mirror-finished surface of the mirror-finished body.

[0009] In the present invention, a preferred embodiment of the method for packaging a mirror-finished object is to place a package in which the mirror-finished object is sealed with the resin film inside a bag, and then seal the bag in a state in which the air inside has been removed. In the above embodiment, the mirror-finished object is protected by a two-layer structure of the bag and the resin film, so that the mirror-finished object can be protected more reliably.

[0010] The mirror-finished body of the present invention has at least one surface that is a mirror-finished surface having an arithmetic mean roughness Ra of 0.2 μm or less, and when a light source is installed in a darkroom so that the illuminance of the mirror-finished surface is 30,000 lux or more and 60,000 lux or less, and the surface of the mirror-finished surface is observed using the light source, there are 5 or less microscopic foreign matter with a circumscribed circle diameter of 1 μm or more per entire surface of the mirror-finished surface.

[0011] In the present invention, the number of minute foreign particles having a circumscribing circle diameter of 1 μm or more on the surface of the mirror-finished surface is as small as 5 or less per entire surface of one mirror-finished surface, so that the mirror-finished surface can be easily cleaned. It goes without saying that it is preferable that the number of minute foreign particles having a circumscribing circle diameter of 1 μm or more per entire surface of one mirror-finished surface is 0, and when both sides of a mirror-finished body are mirror-finished surfaces, the number of minute foreign particles adhering to each of the two surfaces is 5 or less. The above-mentioned darkroom means a room that can completely block out light, and the illuminance in the room is set to 1 lux or less, more preferably 0 lux. Effect of the Invention

[0012] According to the present invention, it is possible to prevent minute foreign matter from adhering to the mirror-finished surface of a mirror-finished body in a simple manner. [Brief description of the drawings]

[0013] [Figure 1] 1 is a plan view showing a package of mirror-finished objects according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a perspective view showing a mirror-finished body of the first embodiment. [Diagram 3] 3 is a schematic diagram showing a state in which a mirror-finished body is placed on a resin sheet in the packaging method for the mirror-finished body according to the first embodiment. FIG. [Figure 4] 10 is a schematic diagram showing a state in which another resin sheet is placed on the mirror-finished body placed on the resin sheet in the packaging method for the mirror-finished body of the first embodiment. FIG. [Diagram 5] 10 is a schematic diagram showing a state in which three sides of two resin sheets sandwiching a mirror-finished body are joined together and the air inside is degassed in the packaging method for the mirror-finished body of the first embodiment. FIG. [Figure 6] FIG. 11 is a plan view showing a package of mirror-finished objects according to a second embodiment of the present invention. [Figure 7] 13 is a plan view showing a state in which the mirror-finished object is placed on the right half of the resin sheet in the packaging method for the mirror-finished object according to the second embodiment. FIG. [Figure 8] 13 is a schematic diagram showing a state in which a resin sheet is folded back, two sides are joined, and the air inside is degassed in the packaging method for the mirror-finished body according to the second embodiment. FIG. [Figure 9] 10A to 10C are schematic diagrams showing a packaging method for a mirror-finished body according to a modified example of each of the above embodiments. [Figure 10] FIG. 11 is a diagram showing detection conditions for a minute foreign object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the packaging method for a mirror-finished body and the mirror-finished body of the present invention will be described with reference to the drawings.

[0015] [First embodiment] A package 30 for a mirror-finished object 10 of this embodiment (hereinafter referred to as package 30) is a package in which the mirror-finished object 10 having a mirror-finished surface 11 is sealed in a bag 20 made of resin film in a vacuum state, as shown in Fig. 1. The mirror-finished object 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 each of the front and back sides of the mirror-finished object 10.

[0016] For example, the mirror-finished body 10 has a diameter of 203 mm to 530 mm, a thickness of 3 mm to 19 mm, and an arithmetic mean roughness Ra of 0.01 to 0.2 μm of the mirror-finished surface 11. This mirror-finished surface 11 is formed by polishing with a polishing machine.

[0017] The bag body 20 is formed in a bag-like shape by overlapping two resin films 21, 22 having an area larger than the mirror-finished surface 11 of the mirror-finished body 10 in a plan view (see FIG. 4), and sealing the outer periphery with a seal part 29. As shown in FIG. 1, the bag body 20 is formed larger than the mirror-finished surface 11 of the mirror-finished body 10 in a plan view, and is sealed with the mirror-finished body 10 accommodated therein. The resin films 21, 22 constituting the bag body 20 are 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 and lubricants. The resin films 21, 22 constituting the bag body 20 are formed into a film shape by inflation molding or the like.

[0018] For example, the bag body 20 has a planar size of 100 mm to 700 mm × 150 mm to 800 mm, and a thickness of 70 μm to 130 μm. The seal portions 29 formed so as to surround the entire periphery are formed at positions 70 mm to 90 mm from the edges of each side, and have a width of 10 mm to 15 mm.

[0019] [Packing method for mirror-finished products] Here, as a conventional method for packaging mirror-finished objects, a bag in which the outer edges of three sides of two overlapping resin films are sealed is opened, the mirror-finished object is stored through the opening, and the air in the bag is evacuated by a vacuum packaging device to seal the bag and put it into a sealed state. In this case, if the edge of the mirror-finished object contacts the inner surface of the bag, there is a possibility that minute foreign matter originating from the bag will adhere to it, so it is necessary to store it in the bag so as not to contact the inner surface of the bag as much as possible, which is troublesome. In addition, when storing a large number of mirror-finished objects in a bag, it is impossible to prevent the edges of all the mirror-finished objects from contacting the bag, and minute foreign matter will inevitably adhere to the mirror-finished object. For this reason, in this embodiment, a package of mirror-finished objects is formed so that a process of storing the mirror-finished object in a bag does not occur.

[0020] In this embodiment, the package 30 for the mirror-finished body 10 is packaged by placing the mirror-finished body 10 on a resin film 21, placing a resin film 22 different from the resin film 21 on the mirror-finished body 10, and sealing the entire periphery of the overlapping portion between the resin film 21 located on the lower side of the mirror-finished body 10 and the resin film 22 located on the upper side while removing the air inside. A specific description will be given below.

[0021] First, as shown in FIG. 3, the mirror-finished body 10 is placed on the center of the resin film 21. Next, as shown in FIG. 4, the resin film 22 is placed on the mirror-finished body 10. Each of these resin films 21, 22 has a rectangular shape in a plan view and is the same size. Then, as shown in FIG. 5, a part of the entire circumference (in this case, the outer periphery of three sides) of the overlapped resin films 21, 22 is sealed by pressing and welding a heated heater rod against the resin film 21. This seal forms a U-shaped (approximately U-shaped) seal part 29 in the resin film 21, and the two resin films 21, 22 are configured into a bag shape (bag body 20). Then, a pipe of a vacuum device 40 is inserted into the opening on one side of the two bag-shaped resin films 21, 22 that is not sealed, and the air in the bag body 20 is evacuated to seal the part on the one side of the bag body 20. As a result, the mirror-finished body 10 is packaged in the bag 20, resulting in a package 30 of the mirror-finished body 10 as shown in FIG.

[0022] When opening the package 30, the three sides of the bag 20 of the package 30 containing the mirror-finished body 10 thus packaged are cut off one by one together with the sealed portion 29, and the resin film 22 located on the upper side of the mirror-finished body 10 is removed (peeled off) so that the resin film 22 does not come into contact with the edge of the mirror-finished body 10, and the mirror-finished body 10 is taken out of the bag 20. The mirror-finished body 10 taken out of the bag 20 has little minute foreign matter attached thereto.

[0023] Specifically, when the mirror-finished body 10 packaged and taken out by the above method is observed in a darkroom with a light source set so that the mirror-finished surface 11 is 30,000 lux or more and 60,000 lux or less, the number of minute foreign objects with a circumscribed circle diameter of 1 μm or more is 5 or less per entire surface of one mirror-finished surface. It is preferable that the number of minute foreign objects with a circumscribed circle diameter of 1 μm or more is 0 per entire surface of one mirror-finished surface. In this embodiment, since both sides of the mirror-finished body 10 are mirror-finished surfaces 11, the number of minute foreign objects of the above size attached to each of the mirror-finished surfaces 11 of the mirror-finished body 10 is 5 or less. The darkroom means a room where light can be completely blocked, and the indoor illuminance is set to 1 lux or less, more preferably 0 lux. One mirror-finished surface 11 includes a processed surface formed on the front side of the mirror-finished body 10, or a processed surface formed on the back side of the mirror-finished body 10.

[0024] In this manner, when the mirror-finished surface 11 of the mirror-finished body 10 of this embodiment is visually observed under conditions of illuminance of 30,000 lux or more and 60,000 lux or less, the number of minute foreign matters having a circumscribed circle diameter of 1 μm or more is 5 or less per entire surface of the mirror-finished surface 11. For example, when the diameter of the mirror-finished surface 11 is 200 mm, the number of minute foreign matters having a circumscribed circle diameter of 31,400 mm or more is 5 or less. 2 When the diameter of the mirror-finished surface 11 is 320 mm, the number of the above-mentioned minute foreign objects is 80384 mm 2 When the diameter of the mirror-finished surface 11 is 380 mm, the number of the above-mentioned minute foreign objects is 113354 mm 2 From these considerations, the area of ​​one mirror-finished surface 11 is 31,400 mm 2 If the circumscribed circle diameter is 1 μm or more, the 2 There will be no more than five per piece.

[0025] The measurement of minute foreign matter on the mirror-finished surface 11 described above is performed for a plurality of observation ranges set by changing at least the values ​​of α, β, and γ, where α is the illumination angle of the angle light source with respect to the perpendicular line passing through the center of the mirror-finished surface 11, β is the angle around the center on the surface of the mirror-finished surface 11, and γ is the distance between the mirror-finished surface 11 and the light source, as shown in Fig. 10. Specifically, the light source is arranged so that the illuminance on the mirror-finished surface 11 is 30,000 lux or more and 60,000 lux or less, and the distance γ from a 300 lumen LED light (light source) to the mirror-finished surface in a darkroom is 1, 3, and 5 cm, and the angles α and β are measured in the ranges of 30°, 45°, and 80°, and the angles β are measured in the ranges of 0°, 60°, 120°, 180°, 240°, and 320° in the angle of Fig. 10. In other words, since there are three angles α, six angles β, and three distances γ of the LED light, minute foreign objects are measured under a total of 54 conditions (108 if the front and back are combined).

[0026] In the packaging method for the mirror-finished body 10 of this embodiment, a resin film 22 different from the resin film 21 is placed on the mirror-finished body 10 located on the resin film 21, and the entire circumference of the overlapping portion of the upper resin film 22 and the lower resin film 21 is joined to form a seal portion 29, thereby making it possible to house the mirror-finished body 10 in the bag-shaped resin films 21, 22 (bag body 20). Therefore, minute foreign matter that occurs when the mirror-finished body 10 is housed in the bag-shaped resin film is not generated, and therefore it is possible to prevent minute foreign matter from adhering to the mirror-finished surface 11 of the mirror-finished body 10.

[0027] For example, when the mirror-finished body 10 is an electrode plate or a sputtering target of a plasma etcher, it is common to take them out of the bag, place them in a vacuum chamber, and after evacuation, apply a voltage to the mirror-finished body 10 to generate plasma. At this time, if a minute foreign object is attached to the mirror-finished surface 11, an abnormal discharge occurs starting from the minute foreign object, and the foreign object is scattered onto the processing substrate in the plasma etcher, and onto the deposition substrate in the sputtering target. In contrast, in this embodiment, it is possible to prevent the adhesion of minute foreign objects to the mirror-finished surface 11 of the mirror-finished body 10, and therefore it is possible to prevent the abnormal discharge starting from the minute foreign object in a later process, and to prevent the foreign object from scattering onto the processing substrate or the deposition substrate.

[0028] Furthermore, the number of minute foreign particles having a circumscribed circle diameter of 1 μm or more on the surface of mirror-finished surface 11 is small, at 5 or less per entire surface of each mirror-finished surface, which facilitates cleaning of mirror-finished surface 11. In particular, when there are no minute foreign particles adhering to both mirror-finished surfaces 11 (when the number of minute foreign particles adhering to either mirror-finished surface 11 is zero), there is no need to clean the mirror-finished body, which further facilitates subsequent processes.

[0029] [Second embodiment] Next, a method for packaging 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 30A of the mirror-finished body 10 in this embodiment (hereinafter referred to as packaging body 30A) is a packaging body in which the mirror-finished body 10 having a mirror-finished surface 11 is sealed in a bag body 20A under a vacuum, as shown in FIG. 6, and differs from the first embodiment in that the bag body 20A is made of a single piece of resin film and in the packaging method of the mirror-finished body 10.

[0030] As shown in Fig. 6, the bag body 20A is formed larger than the mirror-finished body 10 in plan view, and has a shape in which one resin film 23 is folded back once and three sides are sealed with a seal portion 29A. The resin film 23 constituting the bag body 20A is made of polyethylene or the like, as in the first embodiment. The bag body 20A 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, for example. In other words, the planar size of the resin film 23 constituting the bag body 20A is set such that the horizontal length is twice the horizontal length of the bag body 20A.

[0031] [Packing method for mirror-finished products] Package 30A for mirror-finished object 10 is packaged by placing mirror-finished object 10 on resin film 23, placing a part of resin film 23 on mirror-finished object 10, and sealing the entire periphery of the overlapping part of resin film 23 located on the lower side of mirror-finished object 10 and resin film 23 located on the upper side while degassing the internal air. A specific description will be given below.

[0032] First, as shown in FIG. 7, the mirror-finished body 10 is placed on the right side area of ​​the resin film 21 (the area to the right of the center line L1). Next, as shown in FIG. 8, the resin film 21 is folded back at the center line L1 to place a part of the resin film 23 on the mirror-finished body 10. Then, as shown in FIG. 8, the outer periphery of a part of the entire circumference (in this case, two sides (upper and lower sides in FIG. 8)) of the overlapped resin film 23 is sealed by pressing a heated heater rod against it and welding it. This sealing forms a sealed portion 29A in the resin film 23, and the resin film 23 is configured into a bag shape (bag body 20A). Then, a pipe of a vacuum device 40 is inserted into the opening on the one side side of the bag-shaped resin film 23 that is not sealed, and the air in the bag body 20A is evacuated to seal the part on the one side side of the bag body 20A. As a result, the mirror-finished body 10 is packaged in the bag 20A, resulting in a package 30A of the mirror-finished body 10 shown in FIG.

[0033] When opening the package 30A, three sides of the bag 20A of the package 30A containing the mirror-finished body 10 thus packaged are cut off together with the seal portion 29A, and the mirror-finished body 10 is taken out of the bag 20A by peeling back a part of the resin film 23 located on the upper side of the mirror-finished body 10. The taken-out mirror-finished body 10 has little adhesion of minute foreign matter, as in the first embodiment.

[0034] In this embodiment, the resin film 23 is folded back and a portion of it is placed on the mirror-finished body 10 located on the resin film 23, and the entire periphery of the portion where the upper resin film 23 and the lower resin film 23 overlap, excluding the folded back portion, is joined, thereby making it possible to house the mirror-finished body 10 in the bag-shaped resin film 23. As a result, no minute foreign matter is generated when the mirror-finished body is housed in the bag-shaped resin film, and it is possible to prevent minute foreign matter from adhering to the mirror-finished surface of the mirror-finished body.

[0035] The present invention is not limited to the configurations of the above-described embodiments, and various changes can be made to the details of the configuration without departing from the spirit of the present invention. For example, in each of the above embodiments, an example is shown in which the mirror-finished body 10 is packaged with a resin film, but this is not limiting, and as shown in Fig. 9, the package 30 of the mirror-finished body 10 may be further accommodated in a bag 50 and sealed. In this case, since the mirror-finished body 10 is sealed with a resin film, the bag 50 may be a bag shape with three sides closed in advance. In this way, when the package 30 of the mirror-finished body 10 is further accommodated in the bag 50 and the bag 50 is sealed in a state in which the air inside is degassed, the mirror-finished body 10 is protected by a two-layer structure of the bag 50 and the resin film, so that the mirror-finished body 10 can be protected more reliably.

[0036] In each of the above embodiments, the bag bodies 20, 20A and the resin films constituting them have a rectangular shape in plan view, but are not limited thereto, and may have, for example, a circular shape in plan view.

[0037] In the second embodiment, one resin film 23 is folded back, but the present invention is not limited to this. The resin films 21 and 22 of the first embodiment may be overlapped and sealed only on one side, and the upper resin film 22 may be turned up and the mirror-finished body 20 may be disposed on the resin film 21. In this case, the same effects as those of the first and second embodiments can be achieved.

[0038] In the above embodiment, the entire upper and lower surfaces of the mirror-finished body 10 are mirror-finished surfaces 11, but this is not limiting, and for example, only either the upper or lower surface of the mirror-finished body may be a mirror-finished surface. Also, if a step is formed on one surface of the mirror-finished body to reduce the thickness of its outer periphery, the mirror-finished surface is formed only in the inner region of the step. In other words, the area of ​​one surface of the mirror-finished body and the area of ​​the mirror-finished surface do not necessarily match. EXAMPLES

[0039] A silicon disk (Si electrode plate) with a diameter of 380 mm and a thickness of 10 mm was prepared as the sample (mirror-finished body) of Examples 1 to 3 and Comparative Example, a silicon ring (Si ring) with a diameter of 380 mm, a thickness of 10 mm, and a hole diameter of 0.5 mm was prepared as the sample (mirror-finished body) of Example 4, and a silicon target (Si target) with a diameter of 200 mm and a thickness of 6 mm was prepared as the sample (mirror-finished body) of Example 5. For these Examples 1, 2, 4, and 5, the silicon plate, silicon ring, and silicon target were sealed by the method of Pattern 1, for Example 3, they were sealed by the method of Pattern 2, and for the Comparative Example, they were sealed by the conventional method.

[0040] (Method of sealing mirror-finished objects) The sealing method of pattern 1 is to prepare a laminate film (Thermoclean: manufactured by Sumika Sekisui Film Co., Ltd.) of 450 mm x 400 mm with one side already sealed, place a sample (mirror-finished product) on the open laminate film, and cover the product with the open laminate film to close it. Then, seal the two unsealed sides, and seal the last side while degassing at a degassing pressure of 1000 Pa. In other words, the method of pattern 1 is the same as the method of the second embodiment. Finally, place the product in a laminate bag sealed on three sides, and seal the last side while degassing at a degassing pressure of 1000 Pa. The sealing method of pattern 2 involves preparing two laminate films (Thermoclean, manufactured by Sumika Sekisui Film Co., Ltd.) of 450 mm x 400 m with none of the sides sealed, placing a sample on one of the laminate films, and then covering the sample with another laminate film. The three unsealed sides are then sealed, and the last side is sealed while evacuating at a degassing pressure of 1000 Pa. In other words, the method of pattern 2 is the same as the method of the first embodiment. Finally, the sample is placed in a laminate bag sealed on three sides, and the last side is sealed while evacuating at a degassing pressure of 1000 Pa. The conventional sealing method involves preparing a 450mm x 400mm (bag) of laminate film (Thermoclean, manufactured by Sumika Sekisui Film Co., Ltd.) with three sides sealed, and placing the sample (mirror-finished body) inside the bag. Then, seal the last side (the opening of the bag) while evacuating at a degassing pressure of 1000 Pa. Finally, place the sample in a laminate bag that is sealed on three sides, and seal the last side while evacuating at a degassing pressure of 1000 Pa.

[0041] The timing for checking for minute foreign matter was two times: before sealing the sample and after sealing (after cutting the three sides together with the seal part and opening so that the end of the laminate film does not touch the sample). To check for minute foreign matter, first, the sample (mirror-finished body) was placed on an observation table, and a light source was set 10 mm above the foreign matter observation point of the sample so that the illuminance on the sample surface (mirror-finished surface) was 30,000 lux to 60,000 lux, and the sample was visually observed from a 45° inclination. A 300 lumen LED lamp was used as the light source. In addition to this visual observation, the mirror-finished surface (both sides or one side) of the sample was observed by the following method, and the number of minute foreign matter occurrences was counted and evaluated.

[0042] (Method for evaluating the occurrence of minute foreign matter) The measurement of minute foreign matter with a circumscribed circle diameter of 1 μm or more was performed by arranging an LED light so that the illuminance on the mirror-finished surface 11 was 30,000 lux or more and 60,000 lux or less. In a dark room with an illuminance of 1 lux, the distance γ from the 300 lumen LED light to the mirror-finished surface 11 was 1, 3, and 5 cm. In the angle of FIG. 10, the angle α was 30°, 45°, and 80°, and the angle β was 0°, 60°, and 1 Measurements were made over ranges of 20°, 180°, 240°, and 320°. In other words, there were three LED light distances γ, three angles α, and six angles β, so the number of micro-foreign objects was measured under a total of 54 conditions (108 conditions in total when both sides are mirror-finished). In these measurements, micro-foreign objects with a circumscribed circle diameter of 1 μm or more were visually observed. The circumscribed circle diameter of the micro-foreign objects was also measured using a preset scratch scale (minimum scratch area 0.03 mm 2 = 0.001 mm) was used and the measurements were made by comparing it with this scratch scale. Note that the locations where minute foreign matter was detected in the following evaluation are the total number of locations where minute foreign matter was detected in all 54 (108) cases where the distance γ and angles α and β were changed. The evaluation criteria were as follows: if no microscopic foreign matter was found, it was marked "absent", if there were less than 100, the number found was recorded, and if there were 100 or more, it was recorded as "present, 100 or more". The results are shown in Table 2.

[0043] [Table 1]

[0044] [Table 2]

[0045] As shown in Table 2, in Examples 1, 3 to 5, no foreign matter of 1 μm or more was found on the mirror-finished surface. In Example 2, the number of minute foreign matter of 1 μm or more was found to be very small, 5 on the front surface and 4 on the back surface, both before and after sealing. This is thought to be due to the fact that an ionizer for removing static electricity was not used, and particles attracted by static electricity to the mirror-finished surface could not be completely removed. In other words, in Examples 1 to 5, which are packaged by the method of pattern 1 or 2 in which a mirror-finished body is placed on a resin film, a part of the resin film or a resin film different from the resin film is placed on the mirror-finished body, and the entire circumference of the overlapping part between the resin film located on the lower side of the mirror-finished body and the resin film located on the upper side is sealed in a state in which the air inside is degassed, it was found that the number of minute foreign matter attached to the mirror-finished surface can be extremely reduced. In Example 5, the back surface is the surface bonded to the backing plate, so observation is not necessary. On the other hand, in the comparative example, the mirror-finished body (silicon plate) was packaged in a bag, and it was found that the edges of the silicon plate came into contact with each other during packaging, causing a large number of minute foreign objects to adhere to the bag. [Explanation of symbols]

[0046] 10 Mirror finished body 11 Mirror-finished surface 20,20A bag body 21, 22, 23 Resin film 29, 29A Seal part 30,30A Mirror-finished product packaging 40 Vacuum device 50 bags

Claims

1. A mirror-finished body, characterized in that at least one of the surfaces is a mirror-finished surface having an arithmetic mean roughness Ra of 0.2 μm or less, and when a light source is installed in a darkroom so that the illuminance of the mirror-finished surface is 30,000 lux or more and 60,000 lux or less, and the surface of the mirror-finished surface is observed using the light source, there are 5 or less microscopic foreign matter with a circumscribed circle diameter of 1 μm or more per entire surface of the mirror-finished surface.

2. 2. The mirror-finished body according to claim 1, wherein the mirror-finished body is made of silicon.

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