Cleaning method of substrate table for preparing monocrystal diamond

Abstract

The invention relates to a cleaning method of a substrate table for preparing single crystal diamond, and belongs to the technical field of single crystal diamond preparation. The to-be-cleaned substrate table is sequentially subjected to microwave plasma etching, polishing, sand blasting and ultrasonic cleaning, and the cleanliness of the substrate table can be improved. Wherein some graphite and amorphous carbon on the surface of the substrate table can be removed or stubborn polycrystalline phases can be adsorbed through microwave plasma etching, non-single crystal phases on the surface of the substrate table can be further removed through subsequent grinding, the surface of the substrate table can be clean through sand blasting, and the surface roughness of the substrate table can be reduced; and impurities left on the surface of the substrate table in the polishing and sand blasting process can be removed through final ultrasonic cleaning. According to the cleaning method for the substrate table for preparing the monocrystal diamond, operation is easy, the cleaning efficiency is high, the non-monocrystal phase on the surface of the substrate table can be completely removed, the repeated utilization rate of the substrate table is increased, and the production cost is saved.

Description

Technical Field

[0001] The present invention relates to a cleaning method for a substrate stage used for preparing single crystal diamond, belonging to the technical field of single crystal diamond preparation. Background Art

[0002] Microwave plasma chemical vapor deposition (hereinafter referred to as MPCVD) has the advantages of mild reaction, little pollution to samples, fast deposition rate, etc., and is a commonly used method for preparing thin film materials. Especially in the preparation of diamond, its principle is to use microwaves to excite reaction gases (H2, CH4) into a plasma state, and deposit a diamond film on a substrate stage (the substrate stage is usually a circular molybdenum sheet) in the central region of a vacuum chamber. MPCVD increases the reaction rate of precursors through plasma, and is suitable for preparing high-quality hard thin films and crystals with large area, good uniformity, high purity, and good crystal morphology, solving the limitations of traditional plasma technologies. MPCVD is one of the effective means for preparing large-size single crystal diamond. Due to the unique structure of the reaction chamber, in an MPCVD device, spherical or ellipsoidal plasmas are concentrated directly above the substrate stage placed at the center of the vacuum chamber. By placing a single crystal seed wafer on the surface of the substrate stage and setting the process parameters, single crystal diamond can be deposited and grown on the surface of the substrate material (single crystal seed wafer).

[0003] However, in actual use, as the reaction progresses, polycrystalline diamond and other non-single crystal phase deposition impurities will grow in the area of the substrate stage where no seed is placed and under the seed. Polycrystalline diamond and other deposition impurities are wear-resistant and have a high hardness, making them difficult to handle, resulting in the inability to reuse the substrate stage, thereby increasing production costs. Therefore, it is necessary to clean the working surface of the substrate stage. The final state of the substrate stage after cleaning determines its surface characteristics, directly or indirectly affecting the temperature, rate, and quality of single crystal diamond deposition. Therefore, the cleaning effect of the substrate stage surface is very important for the growth of single crystal diamond. Currently, the traditional methods for cleaning the surface of the substrate stage mainly include grinding with a grinding machine or cleaning with a sandblaster, but these methods are difficult to remove the deposition impurities attached to the surface of the substrate stage, resulting in poor cleanliness of the surface of the cleaned substrate stage and affecting the reuse of the substrate stage. Summary of the Invention

[0004] The purpose of the present invention is to provide a cleaning method for a substrate stage used for preparing single crystal diamond, which can solve the problem of poor cleaning effect existing in the current cleaning methods for the substrate stage.

[0005] In order to achieve the above purpose, the technical solution adopted by the cleaning method for a substrate stage used for preparing single crystal diamond of the present invention is as follows:

[0006] A cleaning method for a substrate stage used in preparing single-crystal diamond, comprising the following steps: sequentially performing microwave plasma etching, grinding, sandblasting, and ultrasonic cleaning on the surface of the substrate stage to be cleaned.

[0007] In the present invention, the substrate stage to be cleaned is sequentially subjected to microwave plasma etching, grinding, sandblasting, and ultrasonic cleaning, which can improve the cleanliness of the substrate stage. Among them, microwave plasma etching can remove some graphite, amorphous carbon, or stubbornly adsorbed polycrystalline phases on the surface of the substrate stage. Subsequent grinding can further remove the non-single crystal phases on the surface of the substrate stage. Sandblasting can clean the surface of the substrate stage and reduce the surface roughness of the substrate stage. The final ultrasonic cleaning can remove the impurities remaining on the surface of the substrate stage during the grinding and sandblasting processes. The cleaning method for the substrate stage used in preparing single-crystal diamond of the present invention is simple in operation, high in cleaning efficiency, can completely remove the non-single crystal phases on the surface of the substrate stage, improve the reuse rate of the substrate stage, and save production costs.

[0008] Preferably, the atmosphere of the microwave plasma etching consists of oxygen and hydrogen; the volume ratio of oxygen to hydrogen is not greater than 10:100; the flow rate of hydrogen is 200 - 400 sccm; the pressure of the microwave plasma etching is 12 - 18 kPa, the temperature is 800 - 900 °C, and the time is 30 - 60 min.

[0009] Preferably, the grinding medium used for grinding is a scouring pad, the particle size of the scouring pad is not less than 100 mesh, the rotation speed of the scouring pad is 600 - 3000 r / min, the grinding pressure is 0.5 - 1 MPa, and the moving speed is 1 - 2 m / min.

[0010] Preferably, the abrasive used for sandblasting is quartz sand, the particle size of the quartz sand is not less than 300 mesh, the sandblasting pressure is 0.4 - 0.8 MPa, the sandblasting distance is 100 - 150 mm, and the sandblasting angle is 60 - 90°.

[0011] Preferably, the ultrasonic cleaning includes a first ultrasonic cleaning and a second ultrasonic cleaning performed sequentially. The cleaning agent used for the first ultrasonic cleaning is acetone, the ultrasonic frequency is 35 - 45 kHz, the power is 320 - 420 W, and the time for the first ultrasonic cleaning is 5 - 10 min; the cleaning agent used for the second ultrasonic cleaning is ethanol, the ultrasonic frequency is 35 - 45 kHz, the power is 320 - 420 W, and the time for the second ultrasonic cleaning is 5 - 10 min. Description of the Drawings

[0012] Figure 1 is the external view of the substrate stage to be cleaned in Embodiment 1 of the present invention;

[0013] Figure 2 is the external view of the substrate stage after etching in Embodiment 1 of the present invention;

[0014] Figure 3 This is the appearance diagram of the polished substrate table in Embodiment 1 of the present invention;

[0015] Figure 4 This is the appearance diagram of the substrate table after sandblasting treatment in Embodiment 1 of the present invention;

[0016] Figure 5 This is the appearance diagram of the substrate table after cleaning in Embodiment 1 of the present invention. Detailed implementation manners

[0017] The cleaning method of the substrate table for preparing single crystal diamond of the present invention is a pioneering invention. The substrate table to be cleaned of the present invention is successively subjected to microwave plasma etching, polishing, sandblasting and ultrasonic cleaning, which can improve the cleanliness of the substrate table. Among them, microwave plasma etching can remove some graphite, amorphous carbon or stubbornly adsorbed polycrystalline phases on the surface of the substrate table. Subsequent polishing can further remove the non-single crystal phases on the surface of the substrate table. Sandblasting can make the surface of the substrate table clean and reduce the surface roughness of the substrate table. The final ultrasonic cleaning can remove the impurities remaining on the surface of the substrate table during the polishing and sandblasting processes. The cleaning method of the substrate table for preparing single crystal diamond of the present invention is simple in operation, high in cleaning efficiency, can completely remove the non-single crystal phases on the surface of the substrate table, improve the reuse rate of the substrate table, and save production costs.

[0018] The cleaning method of the substrate table for preparing single crystal diamond of the present invention includes the following steps: successively subjecting the surface to be cleaned of the substrate table to microwave plasma etching, polishing, sandblasting and ultrasonic cleaning.

[0019] In some preferred embodiments, the atmosphere of the microwave plasma etching is mainly composed of oxygen and hydrogen; the volume ratio of oxygen to hydrogen is not more than 10:100; the flow rate of hydrogen is 200 - 400 sccm; the pressure of the microwave plasma etching is 12 - 18 kPa, the temperature is 800 - 900 °C, and the time is 30 - 60 min. For example, the volume ratio of oxygen to hydrogen is (5 - 10):100.

[0020] In some preferred embodiments, the polishing medium used for polishing is a scouring pad, the particle size of the scouring pad is not less than 100 mesh, the rotation speed of the scouring pad is 600 - 3000 r / min, the polishing pressure is 1 - 1.5 MPa, and the moving speed is 1 - 2 m / min. For example, the particle size of the scouring pad is 200 - 500 mesh.

[0021] In some preferred embodiments, the polishing is wet polishing. Wet polishing can avoid generating dust and produce fewer scratches.

[0022] In some preferred embodiments, during polishing, the scouring pad is wetted with ethanol. Ethanol has good solubility and volatility, can reduce the surface tension, and improve the polishing efficiency.

[0023] In some preferred embodiments, the abrasive used for sandblasting is quartz sand, the particle size of the quartz sand is not less than 300 mesh, the sandblasting pressure is 0.4 - 0.8 MPa, the sandblasting distance is 100 - 150 mm, and the sandblasting angle is 60 - 90°.

[0024] In some preferred embodiments, the ultrasonic cleaning includes the first ultrasonic cleaning and the second ultrasonic cleaning carried out in sequence. The cleaning agent used for the first ultrasonic cleaning is acetone, the ultrasonic frequency is 35 - 45 kHz, the power is 320 - 420 W, and the time for the first ultrasonic cleaning is 5 - 10 min; the cleaning agent used for the second ultrasonic cleaning is ethanol, the ultrasonic frequency is 35 - 45 kHz, the power is 320 - 420 W, and the time for the second ultrasonic cleaning is 5 - 10 min. First using ethanol for ultrasonic cleaning and then using acetone for ultrasonic cleaning will result in incomplete cleaning of organic substances such as grease and stains remaining on the sample.

[0025] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] The cleaning method of the substrate stage for preparing single-crystal diamond in this example specifically includes the following steps:

[0028] (1) Place the substrate stage to be cleaned (as shown in Figure 1 ) at the exact center of the microwave plasma deposition chamber. When placing, the surface to be cleaned of the substrate stage (in this example, the surface to be cleaned of the substrate stage is the surface of the substrate stage attached with impurities such as non-single crystals) is placed upward, then cover the chamber lid, and then evacuate the microwave plasma deposition chamber to below 5 Pa, turn on the microwave source for preheating. After the preheating is completed, introduce hydrogen, and the flow rate of hydrogen is 200 sccm, then introduce oxygen, and the volume ratio of oxygen to hydrogen is 5:100. When the pressure in the microwave plasma deposition chamber increases to 1 kPa, start the microwave source and start heating. During the heating process, the power of the microwave source is controlled at 6 kW. When the pressure in the microwave plasma deposition chamber increases to 12 kPa, control the temperature in the microwave plasma deposition chamber at 800 °C, and then carry out microwave plasma etching for 30 min in this state. After the etching is completed, cool down and shut down. After reducing the power of the microwave source to 1 kW and the pressure in the microwave plasma deposition chamber to 1 kPa, turn off the microwave source. After waiting for 5 min to cool, break the vacuum to make the pressure in the microwave plasma deposition chamber return to normal pressure, then open the chamber lid and take out the etched substrate stage; the etched substrate stage is as shown in Figure 2 ; shown byFigure 1 It can be seen that there are obvious deposited impurities such as graphite phase and polycrystalline phase on the surface of the substrate stage to be cleaned. Figure 2 It can be seen that plasma etching can remove part of the polycrystalline phase on the surface of the substrate stage and reduce the adsorption between the more serious part of the polycrystalline and the surface of the substrate stage; the substrate stage in this embodiment is a circular molybdenum sheet.

[0029] (2) Use a grinding machine to wet-grind the etched surface of the substrate stage until there are no residual impurities (no single crystal phase and polycrystalline phase) on the surface of the etched surface of the substrate stage to remove the residual deposited impurities on the etched surface. The grinding medium is a flocked scouring pad, the particle size of the flocked scouring pad is 200 mesh, the power of the grinding machine is 240 W. During grinding, the rotation speed of the scouring pad is 600 r / min, the grinding pressure is 1 MPa, the liquid in which the scouring pad is soaked is ethanol, and the grinding time is 3 min (the moving speed is 2 m / min). The rotation direction of the scouring pad is counterclockwise; in order to avoid scratching the bottom of the molybdenum sheet during the grinding process, before grinding, place the substrate stage on a layer of soft cardboard, then spray ethanol on the etched surface of the substrate stage. After grinding, use a lint-free cloth dipped in ethanol to wipe off the black stains remaining on the surface of the substrate stage after grinding. The substrate stage after grinding is as Figure 3 shown; it can be seen from Figure 3 that after using the scouring pad to grind the substrate stage after plasma etching, the polycrystalline with reduced adsorption on the surface of the substrate stage is removed.

[0030] (3) Turn on the air source and power supply of the sandblaster, and use the sandblaster to sandblast the ground surface of the substrate stage until there are no impurity residues on the ground surface of the substrate stage and the surface is smooth and scratch-free. It can be seen by naked eye that the surface finish is significantly improved. The abrasive used for sandblasting is quartz sand with a particle size of not less than 300 mesh, the sandblasting pressure is 0.4 MPa, the sandblasting distance is 100 mm, and the sandblasting angle is 60°; during sandblasting, the abrasive needs to be slowly added to the hopper to avoid blocking the power supply of the sandblaster. Place the substrate stage in the cabin of the sandblaster, close the cabin door and then perform sandblasting. During sandblasting, the spray gun should maintain an appropriate spraying distance and angle with the substrate stage, and cannot only process the impurity part of the substrate stage. The surface of the substrate stage should be evenly sandblasted to achieve a satisfactory effect. After sandblasting is completed, cut off the power supply and air source of the machine, take out the substrate stage, and turn off the power switch on the electrical box to complete the sandblasting process; the substrate stage after sandblasting is as Figure 4 shown; it can be seen from Figure 4 that after sandblasting, the small amount of polycrystalline remaining on the surface of the substrate stage is eliminated.

[0031] (4) After the surface of the substrate stage after sandblasting treatment, there are impurities such as fine powder remaining. To ensure the cleanliness of the substrate stage, it needs to be ultrasonically cleaned. The specific method of ultrasonic cleaning is as follows: Place the substrate stage after sandblasting treatment into the cleaning basket, pour acetone into it to submerge the substrate stage, place the cleaning basket into the ultrasonic cleaner, turn on the power switch, and conduct the first ultrasonic cleaning. The time for the first ultrasonic cleaning is 5 minutes, the ultrasonic frequency used is 40 kHz, and the power is 360 W. After the first ultrasonic cleaning is completed, pour the used acetone into the acetone waste liquid bottle, then add ethanol to submerge the substrate stage, turn on the power switch, and conduct the second ultrasonic cleaning. The time for the second ultrasonic cleaning is 5 minutes, the ultrasonic frequency used is 40 kHz, and the power is 360 W. After the second ultrasonic cleaning is completed, pour the used ethanol into the alcohol waste liquid bottle to complete the cleaning of the substrate stage. The cleaned substrate stage is as Figure 5 shown. As Figure 5 can be seen, ultrasonic cleaning can remove impurities such as quartz sand and oil stains remaining on the surface of the substrate stage, and further improve the cleanliness of the substrate stage surface.

[0032] Example 2

[0033] The cleaning method of the substrate stage for preparing single-crystal diamond in this example specifically includes the following steps:

[0034] (1) Place the substrate stage to be cleaned in the exact center of the microwave plasma deposition chamber. When placing it, the surface to be cleaned of the substrate stage (in this example, the surface to be cleaned of the substrate stage is the surface with impurities such as non-single crystals attached to the substrate stage) is placed facing upwards, then cover the chamber lid, and then evacuate the microwave plasma deposition chamber to below 5 Pa. Turn on the microwave source for preheating. After the preheating is completed, introduce hydrogen with a flow rate of 400 sccm, and then introduce oxygen. The volume ratio of oxygen to hydrogen is 10:100. When the pressure in the microwave plasma deposition chamber increases to 1 kPa, start the microwave source and start heating up. During the heating-up process, the power of the microwave source is controlled at 10 kW. When the pressure in the microwave plasma deposition chamber increases to 18 kPa, control the temperature in the microwave plasma deposition chamber at 900 °C, and then conduct microwave plasma etching for 60 minutes in this state. After the etching is completed, cool down and shut down. After reducing the power of the microwave source to 1 kW and the pressure in the microwave plasma deposition chamber to 1 kPa, turn off the microwave source. After waiting for 5 minutes to cool down, break the vacuum to make the pressure in the microwave plasma deposition chamber return to normal pressure, and then open the chamber lid to take out the etched substrate stage. The substrate stage in this example is a circular molybdenum sheet;

[0035] (2) Use a grinding machine to perform wet grinding on the etched surface of the substrate stage until there are no residual impurities on the etched surface of the substrate stage (no single crystal phase and polycrystalline phase exist) to remove the residual deposited impurities on the etched surface. The grinding medium is a flocked scouring pad, the particle size of the flocked scouring pad is 300 mesh, the power of the grinding machine is 240 W. During grinding, the rotation speed of the scouring pad is 1500 r / min, the grinding pressure is 0.5 MPa, the liquid in which the scouring pad is soaked is ethanol, the grinding time is 15 min (the moving speed is 1 m / min), and the rotation direction of the scouring pad is counterclockwise;

[0036] (3) Turn on the air source and power supply of the sandblasting machine, and use the sandblasting machine to perform sandblasting on the ground surface of the substrate stage until there are no impurity residues on the ground surface of the substrate stage, the surface is smooth and scratch-free, and it can be seen by naked eye that the surface finish is significantly improved. The abrasive used for sandblasting is quartz sand with a particle size of 500 mesh, the sandblasting pressure is 0.8 MPa, the sandblasting distance is 150 mm, and the sandblasting angle is 90°;

[0037] (4) There are impurities such as fine powder remaining on the surface of the substrate stage after sandblasting. To ensure the cleanliness of the substrate stage, ultrasonic cleaning is required; the specific method of ultrasonic cleaning is as follows: Place the substrate stage after sandblasting into the cleaning basket, pour acetone to submerge the substrate stage, place the cleaning basket into the ultrasonic machine, turn on the power switch, and perform the first ultrasonic cleaning. The time of the first ultrasonic cleaning is 10 min, the ultrasonic frequency used is 35 kHz, and the power is 420 W; after the first ultrasonic cleaning is completed, pour the used acetone into the acetone waste liquid bottle, then add ethanol to submerge the substrate stage, turn on the power switch, and perform the second ultrasonic cleaning. The time of the second ultrasonic cleaning is 10 min, the ultrasonic frequency used is 45 kHz, and the power is 320 W; after the second ultrasonic cleaning is completed, pour the used ethanol into the alcohol waste liquid bottle to complete the cleaning of the substrate stage.

[0038] Example 3

[0039] The cleaning method of the substrate stage for preparing single crystal diamond in this example specifically includes the following steps:

[0040] (1) Place the substrate stage to be cleaned in the exact center of the microwave plasma deposition chamber. When placing it, the surface to be cleaned of the substrate stage (in this embodiment, the surface to be cleaned of the substrate stage is the surface of the substrate stage with impurities such as non-single crystal phases attached) faces upward. Then cover the chamber lid, and evacuate the microwave plasma deposition chamber to below 5 Pa. Turn on the microwave source for preheating. After the preheating is completed, introduce hydrogen with a flow rate of 300 sccm. Then introduce oxygen, and the volume ratio of oxygen to hydrogen is 7:100. When the pressure in the microwave plasma deposition chamber increases to 1 kPa, start the microwave source and begin to heat up. During the heating process, control the power of the microwave source at 8 kW. When the pressure in the microwave plasma deposition chamber increases to 15 kPa, control the temperature in the microwave plasma deposition chamber at 850 °C. Then perform microwave plasma etching for 40 min in this state. After the etching is completed, cool down and shut down. After reducing the power of the microwave source to 1 kW and the pressure in the microwave plasma deposition chamber to 1 kPa, turn off the microwave source. After waiting for 5 min to cool, break the vacuum to restore the pressure in the microwave plasma deposition chamber to atmospheric pressure. Then open the chamber lid and take out the etched substrate stage; the substrate stage in this embodiment is a circular molybdenum sheet;

[0041] (2) Use a grinding machine to perform wet grinding on the etched surface of the substrate stage until there are no residual impurities (no non-single crystal phases and polycrystalline phases present) on the etched surface of the substrate stage to remove the residual deposited impurities on the etched surface. The grinding medium is a flocked scouring pad with a particle size of 500 mesh. The power of the grinding machine is 240 W. When grinding, the rotation speed of the scouring pad is 3000 r / min, the grinding pressure is 0.8 MPa, the liquid in which the scouring pad is soaked is ethanol, the grinding time is 8 min (the moving speed is 1.5 m / min), and the rotation direction of the scouring pad is counterclockwise;

[0042] (3) Turn on the gas source and power supply of the sandblaster, and use the sandblaster to perform sandblasting on the ground surface of the substrate stage until there are no impurity residues on the ground surface of the substrate stage and the surface is smooth and free of scratches. It can be seen by naked eye observation that the surface finish is significantly improved. The abrasive used for sandblasting is quartz sand with a particle size of 400 mesh, the sandblasting pressure is 0.6 MPa, the sandblasting distance is 120 mm, and the sandblasting angle is 70°;

[0043] (4) After the surface of the substrate table is treated by sandblasting, there are impurities such as fine powder remaining. To ensure the cleanliness of the substrate table, ultrasonic cleaning is required. The specific method of ultrasonic cleaning is as follows: Place the substrate table after sandblasting treatment into the cleaning basket, pour acetone into it to submerge the substrate table, put the cleaning basket into the ultrasonic machine, turn on the power switch, and conduct the first ultrasonic cleaning. The time for the first ultrasonic cleaning is 7 minutes, the ultrasonic frequency used is 45 kHz, and the power is 320 W. After the first ultrasonic cleaning is completed, pour the used acetone into the acetone waste liquid bottle, then add ethanol to submerge the substrate table, turn on the power switch, and conduct the second ultrasonic cleaning. The time for the second ultrasonic cleaning is 8 minutes, the ultrasonic frequency used is 35 kHz, and the power is 420 W. After the second ultrasonic cleaning is completed, pour the used ethanol into the alcohol waste liquid bottle to complete the cleaning of the substrate table.

[0044] Comparative Example 1

[0045] The cleaning method of the substrate table for preparing single crystal diamond in this comparative example specifically includes the following steps:

[0046] (1) This step is the same as step (3) of Example 1;

[0047] (2) This step is the same as step (4) of Example 1;

[0048] (3) This step is the same as step (1) of Example 1;

[0049] (4) This step is the same as step (4) of Example 1.

[0050] Comparative Example 2

[0051] The cleaning method of the substrate table for preparing single crystal diamond in this comparative example specifically includes the following steps:

[0052] (1) This step is the same as step (1) of Example 1;

[0053] (2) This step is the same as step (3) of Example 1;

[0054] (3) This step is the same as step (4) of Example 1.

[0055] Comparative Example 3

[0056] The cleaning method of the substrate table for preparing single crystal diamond in this comparative example specifically includes the following steps:

[0057] (1) This step is the same as step (1) of Example 1;

[0058] (2) This step is the same as step (3) of Example 1;

[0059] (3) This step is the same as step (2) of Example 1;

[0060] (4) This step is the same as step (4) of Example 1.

[0061] Experimental Example

[0062] In order to investigate the cleaning effects of the cleaning methods of each example and comparative example, the cleaned substrate tables of each example and comparative example were observed and roughness tested respectively. Whether there are residual impurities on the surface of each substrate table and the roughness test results are shown in Table 1.

[0063] Table 1 Cleaning effects of the cleaning methods of each example and comparative example

[0064] Cleaning method Presence or absence of impurity residue Roughness (μm) Example 1 None 0.70～1.50 Example 2 None 0.50～1.20 Example 3 None 0.60～1.20 Comparative example 1 Yes 1.60～2.00 Comparative example 2 Yes 1.50～2.50 Comparative example 3 None 1.70～2.30

Claims

1. A method for cleaning a substrate stage for preparing single crystal diamond, characterized in that: The following steps are involved: The surface to be cleaned of the substrate stage is sequentially subjected to microwave plasma etching, grinding, sandblasting and ultrasonic cleaning.

2. The method for cleaning a substrate stage for preparing single crystal diamond according to claim 1, characterized in that: The microwave plasma etching atmosphere is composed of oxygen and hydrogen; the volume ratio of oxygen to hydrogen is not greater than 10:100; the flow rate of hydrogen is 200-400 sccm; the pressure of microwave plasma etching is 12-18 kPa, the temperature is 800-900° C., and the time is 30-60 min.

3. The method for cleaning a substrate stage for preparing single crystal diamond according to claim 1, characterized in that: The grinding medium used for the grinding is a scouring pad, the particle size of the scouring pad is not less than 100 meshes, the rotation speed of the scouring pad is 600-3000r / min, the grinding pressure is 0.5-1MPa, and the moving speed is 1-2m / min.

4. The method for cleaning a substrate stage for preparing single crystal diamond according to claim 1, characterized in that: The abrasive used for the sandblasting is quartz sand, the particle size of the quartz sand is not less than 300 meshes, the sandblasting pressure is 0.4-0.8MPa, the sandblasting distance is 100-150mm, and the sandblasting angle is 60-90°.

5. The method for cleaning a substrate stage for preparing a single crystal diamond according to any one of claims 1 to 4, characterized in that: The ultrasonic cleaning includes a first ultrasonic cleaning and a second ultrasonic cleaning performed sequentially, wherein the cleaning agent used in the first ultrasonic cleaning is acetone, the ultrasonic frequency is 35-45kHz, the power is 320-420W, and the time of the first ultrasonic cleaning is 5-10min; the cleaning agent used in the second ultrasonic cleaning is ethanol, the ultrasonic frequency is 35-45kHz, the power is 320-420W, and the time of the second ultrasonic cleaning is 5-10min.

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