Susceptor

Abstract

To provide a susceptor that can precisely control the surface roughness of at least a wafer holding surface, including a ledge portion where a silicon wafer comes into contact with a susceptor, and in which uneven polishing does not occur and contamination is suppressed.SOLUTION: In a susceptor according to the present invention is a susceptor, the entire surface of a substrate made of a carbon material is covered with a thin film 3 made of silicon carbide, and one side of the susceptor has a ledge portion 4a which is an annular region on which a silicon wafer is placed, the surface of the thin film of the ledge portion is a polished surface, there are no protrusions of 20 μm or more on the surface of the thin film of the ledge portion, the variation in surface roughness Sa of the thin film of the ledge portion is within 0.4 μm, and the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the thin film in the ledge portion are 1×1015 atoms / cm3 or less for each element.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention provides Susceptor For example, in an epitaxial film forming apparatus, a wafer is held Susceptor Regarding. [Background technology]

[0002] In epitaxial deposition equipment, which is one type of equipment used in semiconductor manufacturing, a carbon composite material made of a carbon material (called a carbon substrate) covered with silicon carbide (SiC) is used as a susceptor, which is a component that holds silicon wafers. There are several types of susceptors in use, including single-wafer susceptors, which have a recess for accommodating a single wafer formed in a flat susceptor substrate, and susceptors with multiple recesses formed. When manufacturing the susceptor, regardless of the type, the carbon substrate is placed in a predetermined coating furnace, and a silicon carbide (SiC) film is formed on the surface of the carbon substrate by a CVD method or the like, thereby obtaining a susceptor made of a carbon composite material.

[0003] For example, in the case of a single-wafer type susceptor, as shown in Fig. 5, one main surface of a susceptor 50 is formed with a recessed countersunk portion 51 for placing a silicon wafer W thereon. The silicon wafer W is supported by the susceptor 50 by contacting the peripheral edge of the countersunk portion 51. The peripheral edge of the countersunk portion 51 with which the silicon wafer W contacts is called a ledge portion 51a. For example, in Patent Document 1, the susceptor is manufactured by coating SiC on a carbon substrate on which recesses are formed by mechanical grinding or the like, and the susceptor is used in the heat treatment of silicon wafers while still coated. However, when the silicon wafer is subjected to heat treatment or the like while still coated with the SiC coating as in Patent Document 1, there is a risk that the top of the crystal acts like a blade and scratches the surface of the silicon wafer when the crystal grains become large, because SiC is very hard. To solve this problem, for example, Patent Document 2 describes a method in which diamond paper and diamond paste are attached to the tip of a rotary polishing device, and the surface of the recessed portion, including the ledge portion, is polished to adjust the surface roughness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 56-10921 [Patent Document 2] Japanese Patent Application Publication No. 5-283351 Summary of the Invention [Problem to be solved by the invention]

[0005] In the polishing device disclosed in Patent Document 2, diamond paper 71 is attached to a polishing head 70 (rotating surface) at the tip, as shown in Figure 6. The diamond paper 71 generally has a layer of thermosetting synthetic resin 73, such as a resinoid bond, provided on a resin substrate 72, with diamond abrasive grains 74 held in this.

[0006] However, when polishing using this diamond paper 71, the abrasive grains 74 are held in a hard resin layer 73, so if there is distortion on the surface of the recessed portion, the abrasive grain surface may not contact evenly, which could result in uneven polishing. Furthermore, since the diamond abrasive grains 74 are held only on the surface side of the hard resin layer 73, if the diamond abrasive grains 74 fall off, the area where they fell off will be devoid of abrasive grains, which could result in problems such as a significant drop in the polishing rate.

[0007] Furthermore, it is known that the resinoid bond used in the diamond paper 71 contains a high concentration of metal impurities. In the research of the present inventor, the inventor discovered that if the polishing device contains metal impurities, the metal impurities remain in the counterbore, posing a problem in that it takes time and effort to remove the impurities after polishing.

[0008] The present invention has been made under the above circumstances, and provides a susceptor made of a carbon composite material in which the surface of a base material made of a carbon material is covered with a thin film of silicon carbide (SiC), and the surface roughness of the wafer holding surface including at least the ledge portion where the silicon wafer comes into contact with the susceptor can be controlled with high precision, and contamination can be suppressed without causing uneven polishing. Susceptor The purpose is to provide the following. [Means for solving the problem]

[0009] The present invention has been made to solve the above-mentioned problems, and provides a susceptor, comprising a substrate made of a carbon material, the entire surface of which is coated with a thin film made of silicon carbide, A counterbore is formed on one side of the susceptor, and a ring-shaped area is formed on the periphery of the counterbore, on which a silicon wafer is placed. A susceptor having a ledge portion, Annular region The surface of the thin film of the ledge portion is a polished surface, and there are no protrusions of 20 μm or more on the surface of the thin film of the ledge portion, and Annular region The variation in the surface roughness Sa of the thin film of the ledge portion is within 0.4 μm, Annular region The concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the thin film in the ledge area were 1×10 15 atoms / cm 3 It is characterized by the following:

[0010] With a susceptor configured in this manner, when a silicon wafer is placed on the susceptor and a heat treatment is performed to form an epitaxial film on the upper surface of the wafer, the gap between the ledge portion and the lower surface of the silicon wafer can be reduced, and the growth of an unnecessary epitaxial film on the lower surface (rear surface) of the silicon wafer can be suppressed. Furthermore, contamination of silicon wafers with impurity metals can be reduced.

[0011] To solve the above problems, the manufacturing process of the susceptor according to the present invention includes the steps of forming a thin film made of silicon carbide on the entire surface of a substrate, and polishing the thin film on the surface on which the silicon wafer is placed. In the step of polishing the thin film, diamond abrasive grains and a heat-resistant resin are mixed in a rotatable polishing head, and a kneaded and integrated lapping sheet in which the diamond abrasive grains are arranged in multiple layers in the heat-resistant resin is attached. The polishing head is rotated, and the kneaded and integrated lapping sheet is pressed against the thin film to perform the polishing process. The thickness of the kneaded integrated lapping sheet is preferably 60 μm or more and 90 μm or less, and the grain size of the diamond abrasive grains is preferably 10 μm or more and 40 μm or less. Also, the heat-resistant resin is preferably any one of polyimide resin, polyethylene resin, polyethylene terephthalate resin, polyamide resin, and polypropylene resin.

[0012] According to this method, in a susceptor made of a carbon composite material in which the surface of a base material made of a carbon material is covered with a thin film of silicon carbide (SiC), at least the ledge portion that comes into contact with the silicon wafer is polished using a kneaded-integrated lapping sheet formed by kneading a flexible heat-resistant resin and diamond abrasive grains into a sheet, thereby making it possible to precisely control the surface roughness. In other words, if a diamond abrasive grain falls off from the surface of the kneaded, integrated lapping sheet during the polishing process, other diamond abrasive grains will be present underneath the fallen diamond abrasive grain, and these will come out (grow spontaneously) to the surface of the sheet when pressure is applied to the surface to be polished, thereby maintaining the polishing force for a long time and preventing a decrease in the polishing rate. Furthermore, if the kneaded, integrated lapping sheet is flexible and is held by a cushioning material, even if the surface to be polished is distorted, the abrasive grain surface will fit and contact the surface evenly, preventing uneven polishing. Furthermore, in the kneaded and integrated wrapping sheet, the heat-resistant resin has a low concentration of metal impurities, so no metal impurities remain in the recessed portion, making it unnecessary to remove impurities after polishing. The heat-resistant resin is not particularly limited as long as it is an engineering plastic (general-purpose engineering plastic, super engineering plastic) or a general-purpose plastic, but it is more preferable that the heat-resistant resin is any one of polyimide resin, polyethylene resin, polyethylene terephthalate resin, polyamide resin, and polypropylene resin, as these resins are heat-resistant and can be formed into a sheet. [Effects of the Invention]

[0013] According to the present invention, in a susceptor made of a carbon composite material in which the surface of a base material made of a carbon material is covered with a thin film of silicon carbide (SiC), it is possible to precisely control the surface roughness of the wafer holding surface, including at least the ledge portion where the silicon wafer comes into contact with the susceptor, and contamination is suppressed without causing uneven polishing. Susceptor can be provided. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows a CVD apparatus used in manufacturing a susceptor according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a susceptor formed by processing in the CVD apparatus of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the configuration of the polishing apparatus. [Figure 4] FIG. 4 is a cross-sectional view showing a state of polishing processing by the polishing apparatus. [Figure 5] FIG. 5 is a cross-sectional view showing the configuration of a conventional single-wafer susceptor. [Figure 6] FIG. 6 is a cross-sectional view showing the configuration of a conventional polishing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following is a description of the present invention. SusceptorAn embodiment of the present invention will be described with reference to Figures 1 to 4. The figures are schematic or conceptual, and do not accurately depict the relationship between the thickness and width of each part, the size ratio between parts, etc.

[0016] In the susceptor according to the present invention, first, a silicon carbide (SiC) film is formed on the surface of a carbon substrate using, for example, a CVD apparatus 5 as shown in FIG. 1 includes a chamber 10 that forms a processing space, a gas inlet 11 provided on a side surface of the chamber 10 for supplying a carrier gas (hydrogen gas) into the chamber 10, and a gas outlet 12 provided on a side surface of the chamber 10 opposite the inlet 11. The CVD apparatus 5 also includes a support unit 20 for supporting the lower surface of the carbon substrate 2 of the susceptor within the chamber 10. Heater units 15 are provided above and below the chamber 10, and are configured to be able to heat the interior of the furnace to a predetermined temperature.

[0017] When manufacturing a susceptor using this CVD apparatus 5, a carbon substrate 2 made of a carbon material and having a circular counterbore 4 formed therein is placed on a support 20 in a chamber 10. The carbon substrate 2 is for silicon wafers of 4, 5, 6, 8, or 12 inches with a diameter of 50 to 400 mm, for example, and has internal impurity concentrations (metal elements Fe, Ni, and Cr) of 0.05 ppm or less.

[0018] Further, the heater unit 15 is driven to raise the temperature inside the chamber 10 to, for example, 500° C., and the inside of the chamber 10 is evacuated through the gas outlet 12 to create a vacuum state. Next, a carrier gas (H2) is introduced into the chamber 10 at a predetermined flow rate through the gas inlet 11. Thereafter, the temperature inside the chamber 10 is raised to, for example, 1300°C, and source gases (SiCl4, C3H8) are introduced for a predetermined time using H2 as a carrier gas (dilution gas). The source gas concentration inside the chamber 10 at the start of introduction is, for example, 15% to 20%.

[0019] Then, the raw material gas is supplied into the chamber 10 for a predetermined time (e.g., 14 hours) so that the formed film has a predetermined thickness (e.g., 60 μm or more). The raw material gas flows along the upper and lower surfaces of the carbon substrate 2 by the carrier gas and is discharged from the gas outlet 12. When a preset supply time of the source gas has elapsed, the supply of the source gas is stopped.

[0020] By these treatments, a thin film 3 made of silicon carbide (SiC) is formed on the carbon substrate 2 as shown in FIG. Next, the carbon substrate 2 on which the thin film 3 is formed is taken out of the chamber 10, and a polishing process is performed on the countersunk portion 4. Here, the polishing process is performed on at least the ledge portion 4a in the countersunk portion 4 that comes into contact with the silicon wafer W. 3, the polishing device 6 used in this polishing process has a buffer member 9 such as urethane rubber provided on a polishing head (rotating base material) 7b supported by a rotating shaft 7a, and further has a kneaded integrated lapping sheet 8 provided on the buffer member 9. The thickness Tk1 of the buffer member 9 is, for example, 5 mm.

[0021] The kneaded and integrated lapping sheet 8 is formed by kneading diamond abrasive grains 8a with a flexible heat-resistant resin 8b such as polyimide, and the diamond abrasive grains 8a are arranged in multiple layers in the heat-resistant resin 8b, as shown in Figure 3. As mentioned above, the heat-resistant resin can be any engineering plastic (general-purpose engineering plastic, super engineering plastic) or general-purpose plastic, without any particular limitations. More preferably, the heat-resistant resin is one of polyimide resin, polyethylene resin, polyethylene terephthalate resin, polyamide resin, and polypropylene resin, as these resins are heat-resistant and can be formed into a sheet.

[0022] More specifically, the diamond abrasive grains 8a are contained in the heat-resistant resin 8b at a concentration of 20 to 200, more preferably 70 to 130 (for example, 100), and the diamond abrasive grains 8a are arranged substantially uniformly in the sheet surface direction and thickness direction in the sheet-like heat-resistant resin 8b. The diamond abrasive grains 8a arranged on the sheet surface have a high holding force when the heat-resistant resin 8b is, for example, a polyimide resin. However, it is expected that the diamond abrasive grains 8a on the surface of the sheet will fall off as the heat-resistant resin 8b is worn away during polishing. In this case, other diamond abrasive grains 8a will be present underneath the fallen diamond abrasive grains 8a, and these will emerge (spontaneously grow) on the surface side of the consumable sheet 8, thereby maintaining the polishing power for a long time and preventing a decrease in the polishing rate.

[0023] The kneaded and integrated lapping sheet 8 is preferably formed to have a thickness Tk2 of 60 μm or more and 90 μm or less (for example, 75 μm). If the thickness Tk2 of the kneaded and integrated lapping sheet 8 is less than 60 μm, it may be worn away and lost during polishing, and if it is more than 90 μm, it will lose flexibility and will not be able to follow the unevenness of the product (susceptor), which is not preferable. The area of ​​the kneaded and integrated wrapping sheet 8 is, for example, 0.5 cm 2 is formed.

[0024] The grain size of the diamond abrasive grains 8a is selected depending on the target value of the surface roughness Sa of the surface to be polished (target surface roughness Sa value). For example, if the target value of surface roughness Sa is small, such as 1.0 μm or less, diamond abrasive grains 8a with a particle size of 30 to 40 μm are used, and if the target value of surface roughness Sa is larger than 1.0 μm, diamond abrasive grains 8a with a particle size of 10 to 20 μm are used. In this embodiment, the grain size of the diamond abrasive grains 8a is preferably 10 μm or more and 40 μm or less. If the grain size of the diamond abrasive grains 8a is smaller than 10 μm, the polishing efficiency will be extremely poor, and if the grain size of the diamond abrasive grains 8a is larger than 40 μm, tool marks (scratches) will remain on the polished area, which is not preferable.

[0025] Furthermore, since the lapping sheet 8 is flexible and is held by a buffer material 9 such as urethane rubber, even if the surface to be polished is distorted, the abrasive grain surface fits and contacts the surface evenly, preventing uneven polishing. Furthermore, since diamond paper using a resinoid bond as in the past is not used and the concentration of metal impurities in the heat-resistant resin 8b is low, no metal impurities remain in the recessed portion 4, making it unnecessary to perform the work of removing impurities after polishing.

[0026] 4, the polishing by the polishing device 6 is performed by pressing the kneaded integral lapping sheet 8 against the ledge portion 4a of the counterbore portion 4 with a pressure of 2 kgf, setting the polishing head rotation speed to 2000 rpm, and polishing for 2 minutes. After the polishing is completed, the susceptor is washed with hydrofluoric nitric acid or the like to obtain the final susceptor.

[0027] In the susceptor obtained in this manner, the ledge portion 4a, which is the annular region in the recessed portion 4 that contacts at least the underside of the silicon wafer W, is formed so that the variation in the surface roughness Sa (arithmetic mean roughness of the surface) of the thin film 3 is within 0.4 μm. That is, when the silicon wafer W is placed on the susceptor and a heat treatment is performed to form an epitaxial film on the upper surface of the wafer, the gap between the ledge portion 4a and the lower surface of the silicon wafer W can be reduced, and the growth of an unnecessary epitaxial film on the lower surface (rear surface) of the silicon wafer W can be suppressed.

[0028] Furthermore, since the ledge portion 4a of the silicon wafer W is subjected to the polishing process described above, there are no protrusions of, for example, 20 μm or more on the surface of the thin film 3. This prevents the surface of the silicon wafer W from being damaged by protrusions on the susceptor 1 side. Furthermore, as described above, in the case of the heat-resistant resin 8b, the concentration of metal impurities is low, so metal impurities do not remain in the counterbore portion 4. Therefore, the content of metal impurities (Fe, Cr, Cu, Al) in the ledge portion 4a at a depth of 3 μm from the surface of the thin film 3F and in a measurement area of ​​200 μm×200 μm was 1×10 15 atoms / cm 3 This reduces contamination of the silicon wafer with impurity metals.

[0029] As described above, according to the embodiment of the present invention, in a susceptor made of a carbon composite material in which the surface of a substrate 2 made of a carbon material is covered with a thin film 3 of silicon carbide (SiC), at least the ledge portion 4a with which the silicon wafer W comes into contact is polished using the kneaded-integrated lapping sheet 8, thereby enabling the surface roughness to be controlled with high precision. In other words, if diamond abrasive grains 8a fall off from the surface of the kneaded integrated lapping sheet 8 during the polishing process, new abrasive grains 8a will grow from underneath one after another, thereby preventing a decrease in the polishing rate.

[0030] Furthermore, since the kneaded integrated lapping sheet 8 is flexible and is held by a buffer material 9 such as urethane rubber, even if the surface to be polished is distorted, the abrasive grain surface fits and contacts the surface evenly, preventing uneven polishing. Furthermore, in the kneaded and integrated wrapping sheet 8, the heat-resistant resin 8b has a low concentration of metal impurities, so no metal impurities remain in the recessed portion 4, making it unnecessary to remove impurities after polishing.

[0031] In the above embodiment, the kneaded integrated lapping sheet 8 is placed on a buffer member 9 in the polishing device 6, but the present invention is not limited to this configuration, and a configuration without a buffer member 9 is also possible. Furthermore, in the above embodiment, a susceptor having a recessed portion is used as an example, but the present invention is not limited to this form and can also be applied to a susceptor that does not have a recessed portion. Furthermore, in the case where a counterbore portion is provided, the present invention is not limited to a counterbore portion curved in a concave shape as shown in the drawings, and can also be applied to a susceptor having, for example, a cylindrical counterbore portion. [Example]

[0032] The present invention Susceptor This will be further explained based on examples. [Experiment 1] In Experiment 1, it was verified whether the target surface roughness Sa (arithmetic mean roughness of the surface) could be obtained depending on the diamond grain size of the kneaded integrated lapping sheet used in the polishing device. Furthermore, 18 measurement points were randomly selected on the ledge of one susceptor, and the variations in surface roughness Sa were measured.

[0033] Example 1 In Example 1, isotropic graphite was used as the material of the susceptor substrate, and multiple carbon substrates with countersunk portions were prepared. Using the CVD apparatus shown in Figure 1, silicon carbide films were formed on the substrate surfaces under multiple film thickness formation conditions. In the CVD apparatus, a carbon substrate was placed in the chamber, and after evacuation, the chamber was heated to 500°C and a carrier gas (H2) was introduced into the chamber. The chamber was then heated to 1300°C, and the carbon substrate was rotated at a rotational speed of 0.1 rpm without fixing the support position of the carbon substrate. A source gas (SiCl4, C3H8) was supplied along the front and back surfaces of the carbon substrate. After a predetermined time (14 hours), the supply of the source gas was stopped, and after one hour, the rotation of the carbon substrate was stopped, forming a 60 μm-thick silicon carbide thin film on the substrate surface.

[0034] Next, the ledge portion of the counterbore was polished for a certain period of time using a polishing device with the kneaded integrated lapping sheet attached to the polishing head shown in Figure 3. The conditions were: polishing pressure 2 kgf, polishing head rotation speed 2000 rpm, susceptor rotation speed 20 rpm, and polishing time 2 minutes. The kneaded and integrated lapping sheet is made of a flexible heat-resistant resin, polyimide resin, and powdered diamond abrasive grains are kneaded with the polyimide resin to form a sheet with a thickness of 75 μm. The concentration of the diamond abrasive grains in the polyimide resin is 100, and the grain size of the diamond grains is 30 to 40 μm. The sheet area is 0.5 cm 2 It was decided.

[0035] The kneaded, all-in-one lapping sheet was attached to the polishing head via a 5 mm thick urethane rubber plate used as a buffer member. After polishing, 18 measurement areas were randomly selected on the ledge of one susceptor, and the variation in surface roughness Sa was measured. The measurement method was to create a height profile of the measurement area using a laser microscope, and obtain the arithmetic mean roughness Sa of the surface in each measurement area. In Example 1, the variation in the surface roughness Sa of the ledge was within 0.4 μm. Furthermore, when the ledge was observed using a laser microscope, no protrusions greater than 20 μm were found.

[0036] Example 2 In Example 2, the diamond grain size contained in the kneaded-integrated lapping sheet was 10 to 20 μm in the polishing treatment for the ledge portion. The other conditions were the same as in Example 1. After polishing, 18 measurement areas were randomly selected on the ledge of one susceptor, and the variation in surface roughness Sa was measured. The measurement method was to create a height profile of the measurement area using a laser microscope, and obtain the arithmetic mean roughness Sa of the surface in each measurement area. In Example 2, the variation in the surface roughness Sa of the ledge was within 0.4 μm. Furthermore, when the ledge was observed using a laser microscope, no protrusions greater than 20 μm were found.

[0037] (Comparative Example 1) In Comparative Example 1, isotropic graphite was used as the material of the susceptor substrate, and multiple carbon substrates with countersunk portions were prepared, as in Example 1. Using the CVD apparatus shown in Figure 3, silicon carbide films were formed on the substrate surfaces under multiple film thickness formation conditions. In the CVD apparatus, a carbon substrate was placed in the chamber, and after evacuation, the chamber was heated to 500°C and a carrier gas (H2) was introduced into the chamber. The chamber was then heated to 1300°C, and the carbon substrate was rotated at a rotational speed of 0.1 rpm without fixing the support position of the carbon substrate. A source gas (SiCl4, C3H8) was supplied along the front and back surfaces of the carbon substrate. After a predetermined time (14 hours), the supply of the source gas was stopped, and after one hour, the rotation of the carbon substrate was stopped, forming a 70 μm-thick silicon carbide thin film on the substrate surface.

[0038] Next, the ledge of the counterbore was polished for a certain period of time using a polishing device with a polishing head equipped with diamond paper made of diamond abrasive grains held in a resinoid bond (thermosetting synthetic resin) as shown in Figure 6. The conditions were: polishing pressure 2 kgf, polishing head rotation speed 2000 rpm, susceptor rotation speed 20 rpm, and polishing time 1 minute. In the diamond paper, the diamond abrasive grains are arranged in one layer by a resinoid bond, the concentration of the diamond abrasive grains is 100, and the grain size of the diamond grains is 30 to 40 μm. The sheet area is 0.5 cm 2 It was decided. After polishing, 18 measurement areas were randomly selected on the ledge of one susceptor, and the variation in surface roughness Sa was measured. The measurement method was to create a height profile of the measurement area using a laser microscope, and obtain the arithmetic mean roughness Sa of the surface in each measurement area. As a result of Comparative Example 1, the variation in the surface roughness Sa of the ledge face was 0.5 μm or more.

[0039] As a result of Experiment 1, it was confirmed that the variation in surface roughness Sa at the ledge portion was within 0.4 μm, and could be kept small. Furthermore, it was confirmed that the surface roughness Sa of the ledge changes depending on the grain size of the diamond abrasive grains, so it is sufficient to set the grain size of the abrasive grains according to the target surface roughness Sa. On the other hand, it was confirmed that in Comparative Example 1, the variation in surface roughness Sa at the ledge portion was greater than in Examples 1 and 2.

[0040] [Experiment 2] In Experiment 2, it was verified whether the polished SiC film was contaminated with metal impurities on the ledge of the susceptor. To verify whether polishing the ledge portion causes contamination, a susceptor was first manufactured without polishing the ledge portion, and the concentrations of Fe, Cr, Cu, and Al were measured in a measurement area of ​​200 μm × 200 μm at a depth of 3 μm from the surface of the SiC film in the ledge portion. The measurement method used was secondary ion mass spectrometry (SIMS analysis). The manufacturing conditions for the susceptor were the same as in Example 1, except that the ledge portion was not polished. As a result, the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the SiC film were 1×10 15 atoms / cm 3 It was as follows.

[0041] Example 3 In Example 3, the concentrations of Fe, Cr, Cu, and Al were measured in a measurement area of ​​200 μm × 200 μm at a depth of 3 μm from the surface of the SiC film on the ledge of a susceptor manufactured by the same method as in Example 1. Secondary ion mass spectrometry was used as the measurement method. As a result of Example 3, the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the SiC film were 1×10 15 atoms / cm 3 It was as follows. That is, there was almost no contamination by metal impurities compared to when the ledge portion was not polished.

[0042] Example 4 In Example 4, the concentrations of Fe, Cr, Cu, and Al were measured in a measurement area of ​​200 μm × 200 μm at a depth of 3 μm from the surface of the SiC film on the ledge of a susceptor manufactured by the same method as in Example 2. The measurement method was the same as in Example 3. As a result of Example 4, the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the SiC film were 1×10 15 atoms / cm 3 It was as follows. That is, there was almost no contamination by metal impurities compared to when the ledge portion was not polished.

[0043] (Comparative Example 2) In Comparative Example 2, the concentrations of Fe, Cr, Cu, and Al were measured in a measurement area of ​​200 μm × 200 μm at a depth of 3 μm from the surface of the SiC film on the ledge of a susceptor manufactured by the same method as in Comparative Example 1. The measurement method was the same as in Example 3. As a result of Comparative Example 2, the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the SiC film were 1×10 16 More than 1×10 18 atoms / cm 3 It was as follows. That is, compared to when the ledge portion was not polished, it was confirmed that the polishing treatment resulted in contamination with metal impurities.

[0044] As a result of Experiment 2, Examples 3 and 4 show that the concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the SiC film on the ledge of the susceptor were 1×10 15 atoms / cm 3 It was confirmed that the value could be kept as low as [Explanation of symbols]

[0045] 1 susceptor 2. Carbon substrate 3 Thin Film 4 Counterbore 5 CVD equipment 6 Polishing equipment 8. Mixed and integrated wrapping sheet 8a diamond abrasive grain 8b Heat-resistant resin 10 Chambers 11 Gas inlet 12 Gas outlet 20 Support part

Claims

[Claim 1] A susceptor having a substrate made of a carbon material whose entire surface is coated with a thin film made of silicon carbide, a counterbore portion formed on one surface of the susceptor, and a ledge portion formed on the periphery of the counterbore portion as an annular region on which a silicon wafer is placed, the surface of the thin film on the ledge portion of the annular region is a polished surface, and no protrusions of 20 μm or more exist on the surface of the thin film on the ledge portion; and the variation in surface roughness Sa of the thin film of the ledge portion of the annular region is within 0.4 μm; The concentrations of Fe, Cr, Cu, and Al at a depth of 3 μm from the surface of the thin film in the ledge portion of the annular region were 1×10 １５ atoms / cm ３ is A susceptor characterized by:

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