Ceramic wafer and its manufacturing method

Abstract

To provide a ceramic wafer in which a positional deviation from a fixture is improved in a step of cleaning or the like.SOLUTION: In a ceramic wafer of which the outer periphery is formed by an orientation flat part and a circular peripheral part, the surface roughness of the circular peripheral part end surface is larger than that of the orientation flat part end surface. Also, the ratio of the surface roughness of the orientation flat part end surface to the surface roughness of the circular peripheral part end surface is within a range of 1.1 or more and 3.0 or less, and the arithmetic surface roughness Ra of the orientation flat part end surface is preferably 1.5 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments relate to a ceramic wafer and a manufacturing method thereof. [Background technology]

[0002] A silicon nitride substrate is disclosed as a ceramic wafer for arranging a single crystal body (Patent Document 1). According to Patent Document 1, a reference example of a silicon nitride substrate having a high strength of 755 MPa in three-point bending strength is described, and an orientation flat is provided on the circumference to adjust the orientation of the wafer. In addition, a ceramic dummy wafer is a product form similar to a ceramic wafer. Dummy wafers are used to set manufacturing conditions in the film formation process and etching process of semiconductor manufacturing processes. Among dummy wafers, a ceramic dummy wafer that causes less contamination of thin films is disclosed (Patent Document 2). According to Patent Document 1, it has been found that a dummy wafer made of aluminum oxide ceramics does not cause detection omissions by an optical sensor. In addition, a dummy wafer made of the same ceramic with an orientation flat is disclosed (Patent Document 3). In the figure of Patent Document 3, an orientation flat is formed, and a dummy wafer with a diameter of 100 mm and a thickness of 0.635 mm is produced by pressing granulated powder made of aluminum powder or the like and then sintering and processing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6992364 [Patent Document 2] Patent No. 3943197 [Patent Document 3] JP 2003-8647 A Summary of the Invention [Problem to be solved by the invention]

[0004] Ceramic wafers are denser than silicon wafer products and therefore heavier. Therefore, when a heavy ceramic wafer is set on a jig and cleaned with a chemical solution, it falls off the jig. position but In addition, the ceramic dummy wafer has excellent corrosion resistance. It can be washed with chemicals and reused, so it can be used in the same way when cleaning. Location from but The ceramic wafer according to the embodiment has the following problem. This is a solution to the problem of the jig being easily washed during repeated use. The ceramic wafer and ceramic dummy wafer (hereafter referred to as "ceramic") can be set well. (hereinafter referred to simply as "ceramic wafers") It is something. [Means for solving the problem]

[0005] The ceramic wafer according to the embodiment is a ceramic wafer whose outer periphery is composed of an orientation flat portion and a circumferential portion, and is characterized in that the surface roughness of the end face of the orientation flat portion is greater than the surface roughness of the end face of the circumferential portion. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a diagram showing an example of a ceramic wafer according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example in which a ceramic wafer according to an embodiment is set on a jig. [Diagram 3] FIG. 2 is a diagram showing an example in which a ceramic wafer according to an embodiment is set on a jig. [Figure 4] FIG. 13 is a diagram showing an example of a ceramic wafer set on a jig. [Diagram 5]FIG. 2 is a diagram showing an example of a process flow using a ceramic wafer according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The ceramic wafer according to the embodiment is a ceramic wafer whose outer periphery is composed of an orientation flat portion and a circumferential portion, and is characterized in that the surface roughness of the end face of the orientation flat portion is greater than the surface roughness of the end face of the circumferential portion.

[0008] An example of a ceramic wafer according to an embodiment is shown in Fig. 1. In Fig. 1, 1 is a ceramic wafer, 2 is an orientation flat portion, and 3 is a circumferential portion. The size (length) of the orientation flat (hereinafter simply abbreviated as "orientation flat") of the ceramic wafer according to the embodiment varies.

[0009] An orientation flat is a flat portion formed on a semiconductor wafer (hereinafter simply referred to as "wafer") to indicate the crystal orientation of the wafer. For this reason, similar orientation flats are also formed on ceramic wafers used in the same wafer manufacturing process. The edge face of a ceramic wafer with an orientation flat is curved at the circumferential portion and flat at the orientation flat portion. The ceramic wafer according to the embodiment is a ceramic wafer whose outer periphery consists of an orientation flat portion and a circumferential portion, and is characterized in that the surface roughness of the edge face of the orientation flat portion is greater than the surface roughness of the edge face of the circumferential portion.

[0010] Surface roughness is a measure of surface quality, and is measured by the amount of vertical deviation when comparing the surface shape of an object with an ideal surface. If the deviation is large overall, the surface is rough, and if it is small, the surface is smooth. Surface roughness is It is defined in JIS-B-0601 (2013). There are various methods for evaluating surface roughness depending on the characteristics, but any evaluation method can be used as long as it is easy to measure. Representative surface roughness indices are arithmetic mean height (Ra), maximum height (Rz), maximum peak height (Rp), maximum valley depth (Rv), and maximum profile height (Rt), but other surface roughness indices can also be used.

[0011] The measurement method for Ra, Rz, Rp, Rv, and Rt shall be in accordance with JIS-B-0601 (2013). The measurement conditions are: measurement length: 4.0 mm, measurement speed: 0.6 mm / s, shape removal: least squares straight line, λs filter: yes, λs cutoff ratio: 300, cutoff type: Gaussian, cutoff wavelength (λc): 0.8 mm. Each roughness is calculated by rounding off the measured value to two decimal places. If a measurement length of 4.0 mm cannot be ensured in one measurement, it may be measured multiple times. The measurement points may be any points within the range where the measurement part forms the orientation flat and the circumference.

[0012] A number of ceramic wafers are set on a jig made of plastic or the like and swung in chemicals or cleaning water. In order to clean efficiently, it is necessary to set many ceramic wafers on the jig and swung it widely. However, ceramics are heavier than wafers because they have a higher density. For this reason, heavy ceramics Su When an EH is set on a jig for cleaning, if it is swung too quickly it will come off the jig. Conversely, if it is swung slowly and gently so that it does not come off the jig, the cleaning efficiency decreases. Furthermore, among ceramic wafers, ceramic dummy wafers (hereafter simply referred to as "dummy wafers") are used repeatedly, so they are cleaned with chemicals more frequently than ceramic wafers.

[0013] FIG. 2 shows an example of a ceramic wafer according to the embodiment set on a jig. The jig is inclined so that the dummy wafer can be easily inserted and removed. Also, grooves are formed so that multiple ceramic wafers can be placed on the jig. 3 In the case of the OM-100, the end face of the OM-100 is in contact with the jig flat. By making the surface roughness of the end face of the OM-100 larger than that of the circumferential part, As shown in Figure 4 This can prevent the ring from slipping on the jig, as compared to when the ring swings in contact with the jig plane only at the circumferential portion.

[0014] The ceramic wafer according to the embodiment has an outer periphery including an orientation flat portion and a circumferential portion. A ceramic wafer comprising: The surface roughness is larger than that of the circumferential end face. Orientation for surface roughness of circumferential end face The surface roughness ratio of the flat end face is , in the range of 1.1 to 3.0. Surface roughness If the ratio is less than 1.1, the effect of roughening the orientation flat will be small, and the Also, if the magnification is more than 3.0 times, the effect of preventing the jig from coming off can be obtained, but This is because the processing required to increase the roughness of the end face of the orientation flat is costly. In addition, ceramics have the characteristic of being hard but brittle, which increases the surface roughness of the end face of a thin shape. If the cutting is performed in this way, the unevenness of the edges of the flat surface and end surface will increase, which may cause chipping. In addition, if the edges of ceramic wafers are easily chipped, it may cause damage during semiconductor manufacturing processes such as film formation. The edges may chip during cleaning or transportation, resulting in contamination. Furthermore, the edge of the dummy wafer is chipped due to repeated regeneration processes, resulting in contamination. This increases the possibility that Orientation function for surface roughness of the circumferential end face The surface roughness ratio of the rat end surface is , 1.1 to 3.0, or 1.5 to 2.5 It is preferable that the ratio is in the range of 1:1.

[0015] Furthermore, by increasing the surface roughness of the orientation flat end face, it is possible to prevent the orientation flat from slipping on the jig that it is placed in contact with. For this reason, the arithmetic surface roughness Ra of the orientation flat end face is 1.5 μm or more. Even when set in a normal cleaning jig, if the arithmetic surface roughness Ra is less than 1.5 μm, the anti-slip effect is reduced even if the orientation flat is made rougher than the circumferential part, and there is a possibility that it will come off the jig when it is swung. Furthermore, although there is no limit to the range of the maximum arithmetic mean surface roughness, if it is more than 10.0 μm, it will come off the jig. Hard Although this method is effective, it is costly to process the end face of the orientation flat to increase its roughness. Furthermore, ceramics are hard but brittle, and processing the end face of a thin shape to increase its surface roughness may increase the unevenness of the edges between the flat and end faces, making them more likely to chip. Furthermore, if the edges of a ceramic wafer are prone to chipping, the edges may chip during semiconductor manufacturing processes such as film formation, cleaning, transportation, and the dummy wafer regeneration process, resulting in contamination. For this reason, the arithmetic surface roughness Ra of the end face of the orientation flat is preferably within a range of 1.5 μm to 10.0 μm, and more preferably 2.0 μm to 8.0 μm.

[0016] Ceramic wafers are made of silicon nitride, aluminum nitride, aluminum oxide (alumina), and silicon carbide or 1 Silicon nitride is preferably a material having a three-point bending strength of 60 The thermal conductivity can be increased to 50W / (m This allows the heat dissipation properties of the thin type to be increased to 80W / (m·k) or more, and even to 80W / (m·k) or more. It is an excellent ceramic wafer. Aluminum nitride has a three-point bending strength of 300 to 450. MPa, but the thermal conductivity is 170W / (m k) or more, and even 200W / (m k) or more. This results in a ceramic wafer with high heat dissipation. The three-point bending strength is about 300 to 450 MPa and the thermal conductivity is about 20 W / (m·k). Silicon carbide is a versatile ceramic wafer because it is inexpensive. Ceramic wafers with excellent chemical resistance, but with a strength of about 300 to 450 MPa In particular, ceramic wafers with functions such as semiconductors and piezoelectrics on the surface are used. In this case, it is preferable to use the same type of dummy wafer with similar characteristic values. By utilizing the characteristics of each dummy wafer material, ceramic wafers and different types of dummy wafers It is also possible to use

[0017] In addition, it is desirable that the size of the ceramic wafer conforms to the diameter and orientation flat determined by the SEMI standard (Semiconductor Equipment and Materials International), which is the standard for silicon (semiconductor) wafers. If the size is the same as that of a silicon wafer, the equipment and jigs can be shared. For example, a 2-inch wafer has a diameter of 50.8 mm, a thickness of 279 μm, and an orientation flat of 15.88 mm, while an 8-inch wafer has a diameter of 200 mm, a thickness of 725 μm, and an orientation flat of 57.5 mm. Silicon wafers are becoming larger, such as 12 inches (300 mm), and the size of ceramic wafers is also becoming larger. In response to this, the thickness of the ceramic wafer is adjusted according to the application. In other words, if heat dissipation is desired rather than insulation, the ceramic wafer will be thinner than the standard value, and if insulation is desired rather than heat dissipation, the ceramic wafer will be thicker than the standard value. For this reason, the thickness of the ceramic wafer is preferably within the range of 0.2 mm to 3 mm.

[0018] Representative resins used for jigs include polypropylene (PP), fluororesin (PFA), polycarbonate (PC), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), and polytetrafluoroethylene (PTFT). The top of the roughly rectangular parallelepiped jig has a rectangular opening to allow easy insertion and removal of wafers. The jig also has a slope from the bottom to the sides to support and store wafers. Grooves are formed on the bottom and sides to store multiple wafers. Multiple wafers are inserted through the opening and aligned in a parallel state. One or both sides of the jig that correspond to the outermost surface of the aligned multiple wafers may be open to improve cleaning and draining effects. The side of the jig where the multiple outer wafers are placed may have slits to improve cleaning and draining effects. The jig with the wafers placed in it is clamped by the handle to move and clean it. The handle is U-shaped and the bars at the ends of both legs are fitted into the grooves of the jig to attach it.

[0019] Figure 5 shows an example of the manufacturing process flow for semiconductor products that use ceramic wafers. Depending on the process, the process from film formation to cleaning after resist removal may be repeated. Of these, cleaning is a process to remove dirt and stains from the wafer. The dirt and stains that are targeted in cleaning include dust and dirt present in the air, metals generated from equipment and chemicals, organic matter generated from paint and resin parts, and oils and grease generated by workers. This dirt and stains are removed by the process of creating the circuit patterns. edge This can cause defects as foreign matter in the semiconductor device. For this reason, the cleaning process is important for ensuring the quality of semiconductor products.

[0020] In the case of ceramic wafers, single crystals are placed on the surface and then diced to create a semiconductor. It can be used to make conductive products. Examples of single crystals include silicon and compound semiconductors. The semiconductors are GaN-based, In N-based, AlN-based, SiC-based, etc. GaN-based N, GaInN, GaAlN, GaInAlN, etc. The process of placing the single crystal body is as follows: Processes such as stacking single crystals on ceramic wafers and growing single crystals Examples include .Ma In addition, the step of laminating the single crystal on the ceramic wafer is A method of placing a single crystal directly on a wafer is also available. After the thin film is formed, the single crystal may be disposed. Before the crystal growth process, the ceramic wafer is A thin film may be formed on the substrate.

[0021] Dummy Wear Ha is Used to test and adjust manufacturing equipment in some or all of the semiconductor manufacturing process. Since the dummy wafer is used repeatedly, for example, when it is used for film formation in FIG. The film is removed and reused. In this case, the film is immersed in the chemical solution to be removed and then washed with the chemical solution. There is a process.

[0022] These solvent immersions and cleaning are carried out in multi-tank or single-tank batch tanks. In the multi-tank type, the wafers are immersed in a processing tank containing chemicals, and cleaning is performed by rinsing off any chemicals adhering to the wafers and jigs with pure water or the like. In the single-tank type, immersion and cleaning are performed by replacing the chemicals in one processing tank. In both the multi-tank and single-tank types, a large number of wafers can be processed at once by setting the wafers in a jig. In order to process a large number of wafers quickly and uniformly, it is necessary to rock them in each tank. preferable .

[0023] Next, a method for manufacturing a ceramic wafer according to an embodiment will be described with a silicon nitride wafer as an example. As long as the silicon nitride wafer according to the embodiment has the above configuration, the manufacturing method is not limited, but the following method can be used to obtain the wafer with a good yield. First, silicon nitride powder and sintering aid powder are prepared. The amount of sintering aid added is within the range of 1 mass% to 20 mass%. The sintering aid can be one or more oxides selected from rare earth elements, magnesium, hafnium, and titanium. In particular, it is preferable to use an oxide of a rare earth element as an essential component and add one or more oxides selected from magnesium, hafnium, and titanium. A mixed raw material powder of silicon nitride powder and sintering aid powder is prepared.

[0024] The mixed raw material powder is mixed with a binder and the like to prepare a raw material powder slurry. Next, a molding process is carried out using the raw material powder slurry. The molding process can be carried out by a known method such as a sheet molding method or an extrusion molding method. In addition, the obtained molded body can be used as a target. vinegar It is preferable to process the green sheet into a shape that satisfies the requirements. For example, a green sheet formed by a sheet molding method can be punched out with a circular die to obtain a disk-shaped green sheet, and a disk-shaped green sheet with an orientation flat can be obtained by using a disk die with an orientation flat. In addition, the green sheet may be laminated to adjust the thickness.

[0025] In the case of press molding without using sheet molding, the raw material powder slurry is granulated by a spray drying method or the like and molded by die pressing. It is preferable to process the obtained molded body into a desired shape. For example, a disk-shaped mold can be obtained by press molding using a circular mold. shape The body is molded into a disk shape with an orientation flat by a die with an orientation flat. shape You can get a body.

[0026] Next, the compact is degreased at a temperature preferably within the range of 300° C. to 700° C. The resulting degreased compact is sintered at a temperature preferably within the range of 1600° C. to 1900° C.

[0027] Next, the end faces of the obtained silicon nitride sintered body are processed. If not, stack them and perform wire cutting or polishing, or perform laser processing one by one. The circumference and the orientation flat are formed by cutting the material with wire cutting. Since the surface roughness of the machined surface is small, the number of times of cutting on the orientation flat is more than that on the circumference. Less Example: For example, by machining the circumference twice and the orientation flat once, the surface roughness of the orientation flat can be improved. In the case of polishing, the size of the grindstone used can be increased. This reduces the surface roughness of the machined surface, so the orientation flat is made smaller than the circumference. stomach Grit stone By processing with a laser, the surface roughness of the orientation flat can be increased. , the laser dot width is small and surface roughness of the machined surface Saha Since the diameter is smaller than the circumference, Rabu of Laser dot width Large By doing so, the surface roughness of the orientation flat is increased. can be done.

[0028] If the sintered body is in a disk shape, an orientation flat is formed. The orientation flat can be formed by wire cutting, polishing, or laser processing. In each case, the processing conditions are adjusted so that the surface roughness of the orientation flat is greater than that of the circumferential part. Furthermore, if the orientation flat is already formed in the shape of a disk, or if the surface roughness of the end face of the orientation flat is not large after the above-mentioned processing, the surface roughness can be increased by blasting treatment or the like.

[0029] Next, the surface (both the front and back sides) of the obtained silicon nitride sintered body is polished. Although it is possible to perform the surface processing before the end face processing, it is preferable to perform it after, since the surface roughness of the front face is often processed to be smaller than that of the end face.

[0030] (Examples 1 to 7, Comparative Examples 1 to 6) The following ceramic wafers were prepared. The silicon nitride sintered body is one to which an oxide of a rare earth element and one or more oxides of magnesium, hafnium, and titanium are added as sintering aids. The aluminum nitride sintered body is one to which an oxide of a rare earth element is added as a sintering aid. The aluminum oxide sintered body is one to which one or more sintering aids selected from an alkaline earth metal compound and a silicon compound are added. The silicon carbide is one to which one or more sintering aids selected from boron, carbon, and their compounds are added.

[0031] Silicon nitride, aluminum nitride, aluminum oxide, Silicon carbide In the case of green sheets, the raw material powder to which an auxiliary agent had been added was mixed with resin and an organic solvent to form a slurry, which was then molded into a sheet using a sheet molding machine. The green sheet was punched into a square shape using a die to obtain a square green sheet. The green sheet was degreased and then sintered to obtain a sintered body. The sintered body was processed into a circumference and orientation flat using laser, wire processing, and polishing to obtain a sintered body. In addition, the green sheet was punched into a circle using a die and the orientation flat was cut to obtain a disk-shaped green sheet with an orientation flat. The green sheet was degreased and then sintered to obtain a sintered body with an orientation flat. Sintered bodies that were not processed or that were blasted were obtained.

[0032] Next, the surfaces (front and back) of the disk-shaped ceramic wafer are polished to reduce the arithmetic mean roughness Ra to 0.1μ. m andThe obtained ceramic wafer is shown in Table 1. The circumference diameter of 150.0 mm corresponds to 6 inches, and the circumference diameter of 76.2 mm corresponds to 3 inches.

[0033] [Table 1]

[0034] Next, the surface roughness of the circumference edge and orientation flat edge of the ceramic wafer was measured. The measurement conditions for the arithmetic mean surface roughness Ra were as described above. Table 2 shows the arithmetic mean roughness A of the orientation flat edge, the arithmetic mean roughness B of the circumference edge, and the ratio of A to B (A / B). The arithmetic mean roughness was rounded off to one decimal place.

[0035] The arithmetic mean roughness Ra of the ceramic wafer according to the embodiment is set to 1.5 μm or more. In the comparative example, the arithmetic mean roughness of the end face of the orientation flat portion is small. Mixed Wafer The surface roughness of the end face of the orientation flat relative to the surface roughness of the end face of the circumference A is the ratio The value of / B was in the range of 1.1 to 3.0. The comparative example was smaller than 1.1. It is.

[0036] Next, 25 ceramic wafers from Example 1 were placed in a PFA jig capable of storing 25 wafers as shown in Figure 3, with the orientation flats in contact with the inclined surface of the jig. A test was performed in which the jig containing the ceramic wafers was placed in a tank with pure water flowing upward in the center, and the jig was swung up and down 30 cm 10 times before being removed. The amount of displacement of the ceramic wafers from the placement point was checked. Displacement was measured by marking the ceramic wafers and the jig, and the markings, which were arranged so that they overlap, were 5 mm or more for a 150 mm diameter ceramic wafer after the test, and 10 mm or more for a 250 mm diameter ceramic wafer. 100mm diameter ceramic wafer with 4mm or moreFor a ceramic wafer with a diameter of 76.2 mm, a deviation of 3 mm or more was deemed to have occurred. The jig and ceramic wafer were then dried, the ceramic wafer was removed from the jig, and the test was repeated with the ceramic wafer placed in the jig again to check the amount of deviation. After the above test was performed a total of four times on a total of 100 ceramic wafers, the pure water in the tank was replaced, and similar tests were repeated using the same jig for the other examples and comparative examples. The percentage of cases where deviation from the jig was confirmed as a result of the test is shown in Table 2 as the cleaning test results.

[0037] [Table 2]

[0038] As can be seen from the table, the ceramic wafer according to the embodiment has little positional deviation due to the cleaning test. It was found that the ceramic wafer placed on the jig was fixed in place without moving due to the vibration. This shows that controlling the arithmetic mean roughness of the orientation flat is effective. As a comparative example, R The ratio of the arithmetic mean roughness of the flange to the arithmetic mean roughness of the circumference is outside the range In the cleaning test, the position shift increased. The arithmetic mean values ​​outside the range showed increased positional deviation in the cleaning test results. This means that the ceramic wafers will move due to the shaking, increasing the possibility of them falling off.

[0039] In order to compare with evaluation using surface roughness indices other than the arithmetic mean roughness, implementation The maximum height and other surface roughness measurements were taken for the sample in Example 1. The measurement results are shown in Table 3. As can be seen from the table, when the surface roughness of the orientation flat is high in terms of the arithmetic mean roughness, it is possible to use this as an index even when other indices are used, because the orientation flat is rough.

[0040] [Table 3]

[0041] Although some embodiments of the present invention have been illustrated above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. In addition, the above-mentioned embodiments can be implemented in combination with each other. [Explanation of symbols]

[0042] 1...Ceramic wafer 2…Orientation flat section 3...Circumference 4…Jig

Claims

1. In a ceramic wafer whose outer periphery consists of an orientation flat portion and a circumferential portion, The surface roughness of the end face of the irradiated flat portion is greater than the surface roughness of the end face of the circumferential portion, The arithmetic surface roughness Ra of the end face of the irradiance flat is 1.5 μm or more. A ceramic wafer.

2. The ratio of the surface roughness of the end face of the orientation flat to the surface roughness of the end face of the circumferential portion is 1.

2. The ceramic wafer according to claim 1, wherein the porosity is in the range of 0.1 to 3.

0. Ha.

3. The ceramic wafer may be made of aluminum oxide, aluminum nitride, silicon nitride, or carbide.

3. The ceramic according to claim 1 or 2, characterized in that the ceramic is any one of silicon. Swaeda.

4. The ceramic wafer is characterized in that the single crystal is disposed on the ceramic wafer.

3. The ceramic wafer according to claim 1 or 2.

5. 2. The method according to claim 1, wherein the ceramic wafer is a ceramic dummy wafer. The ceramic wafer according to claim 2.

6. In a ceramic wafer whose outer periphery consists of an orientation flat portion and a circumferential portion, The surface roughness of the end face of the irradiated flat is greater than the surface roughness of the end face of the circumferential part, and The arithmetic surface roughness Ra of the end face of the orientation flat portion is processed to 1.5 μm or more; The processing method is one or more of the following: laser, wire cutting, polishing, and blasting. A method for producing a ceramic wafer, comprising the steps of:

7. The ratio of the surface roughness of the end face of the orientation flat to the surface roughness of the end face of the circumferential portion is 1. The ceramic material according to claim 6, characterized in that it is processed to have a value in the range of 0.1 to 3.

0. A method for manufacturing a wafer.

8. The ceramic wafer may be made of aluminum oxide, aluminum nitride, silicon nitride, or carbide. The method according to claim 6 or 7, characterized in that the material is one of silicon. The manufacturing method of the ceramic wafer described above.

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