A cavity structure for an MPCVD apparatus

Abstract

This utility model discloses a cavity structure for an MPCVD device, comprising a microwave cavity assembly, a main cavity assembly, a lower cavity assembly, and a bellows assembly connected sequentially from top to bottom. The microwave cavity assembly includes a first water-cooling assembly and an air-cooling assembly. A stage assembly is vertically mounted within the main cavity assembly, the lower cavity assembly, and the bellows assembly. The stage assembly includes a sample stage and a cavity plate, which are slidably connected. This utility model adds an air-cooling structure, using a combined water and air cooling method. The first water-cooling assembly and the air-cooling assembly, located within the microwave cavity, reduce the temperature of the vacuum-sealed quartz glass, preventing it from being burned out by high temperatures.

Description

Technical Field

[0001] This utility model relates to the field of diamond production equipment technology, and in particular to a cavity structure for MPCVD equipment. Background Technology

[0002] MPCVD equipment is used to grow single-crystal and polycrystalline diamond in batches. The principle of MPCVD is as follows: carbon-containing gas (such as methane) and hydrogen are introduced into a vacuum reaction chamber, and microwave energy is used to excite the gas to form plasma. At high temperature, carbon atoms are deposited on a substrate (molybdenum material) to form diamond crystals. It has advantages such as no pollution, fast deposition rate, high film quality and easy control.

[0003] MPCVD equipment mainly includes a microwave system, a vacuum reaction chamber, a gas delivery system, a temperature and pressure control system, and a water cooling system. Existing MPCVD equipment only uses water circulation to dissipate heat from the chamber. However, as microwave power increases, heat generation also increases, and the water circulation flow rate and temperature need to be adjusted accordingly. After continuous use for a period of time, the heat accumulated per unit time increases, causing the temperature inside the chamber to rise. This raises the temperature of the vacuum-sealed quartz glass at the top of the vacuum chamber (the quartz glass plays a role in vacuum sealing and microwave transmission in this chamber), potentially leading to burnout. Utility Model Content

[0004] To address the aforementioned problems, this invention provides a cavity structure for MPCVD equipment, which solves the problem that existing PCVD equipment only uses water circulation to dissipate heat from the cavity, and the vacuum-sealed quartz glass at the top of the cavity is easily burned out after long-term use.

[0005] This utility model is implemented as follows: A cavity structure for an MPCVD device includes a microwave cavity assembly, a main cavity assembly, a lower cavity assembly, and a bellows assembly connected sequentially from top to bottom. The microwave cavity assembly includes a first water-cooling assembly and an air-cooling assembly. A stage assembly is vertically mounted inside the main cavity assembly, the lower cavity assembly, and the bellows assembly. The stage assembly includes a sample stage and a cavity plate, and the sample stage and the cavity plate are slidably connected.

[0006] Furthermore, the microwave cavity assembly includes a microwave connecting cavity, which includes a first outer cylinder and a first inner cylinder arranged coaxially, forming a first water-cooling cavity between the first outer cylinder and the first inner cylinder, and a first upper flange is fixedly connected to the top of the microwave connecting cavity, and a first lower flange is fixedly connected to the bottom of the microwave connecting cavity.

[0007] Furthermore, the first water-cooling assembly includes a first water inlet pipe and a first water outlet pipe. The first water inlet pipe is located below the first water outlet pipe. One end of the first water inlet pipe and the first water outlet pipe passes through the first outer cylinder and is connected to the first water-cooling cavity.

[0008] Furthermore, the air-cooling assembly includes two air inlet pipes and multiple air outlet pipes. One end of each air inlet pipe and air outlet pipe passes through the first outer cylinder and the first inner cylinder in sequence, and is connected to the inner cavity of the first inner cylinder. The air inlet pipes are inclined, and the air outlet pipes are horizontal.

[0009] Furthermore, the main cavity assembly includes a main reaction cavity, which includes a second outer cylinder and a second inner cylinder arranged coaxially, forming a second water-cooling cavity between the second outer cylinder and the second inner cylinder. A second upper flange is fixedly connected to the top of the main reaction cavity, and the second upper flange is fixedly connected to the first lower flange. A second lower flange is fixedly connected to the bottom of the main reaction cavity.

[0010] Furthermore, the main reaction chamber is connected to a second water inlet pipe, a second water outlet pipe, and an air inlet pipe, and the main reaction chamber is provided with multiple air supply holes.

[0011] Furthermore, the lower cavity assembly includes a single-layer lower cavity, the top of which is fixedly connected to a third upper flange, the bottom of which is fixedly connected to a third lower flange, and the outer periphery of which is connected to a magnetofluid pipeline and a vacuum pumping pipeline.

[0012] Furthermore, the sample stage is slidably connected to the main cavity assembly via a first lifting device. The first lifting device includes a first motor reducer fixedly mounted on the lower cavity assembly. A ball screw is fixedly connected to the output shaft of the first motor reducer. A nut is threaded onto the outer side of the ball screw. A fixed seat is fixedly connected to the nut. The bottom of the bellows assembly is fixedly connected to both the fixed seat and the sample stage.

[0013] Furthermore, the cavity plate is slidably connected to the sample stage via a second lifting device. The second lifting device includes a second motor reducer, and a magnetic fluid shaft is fixedly connected to the output shaft of the second motor reducer. A gear is fixedly provided at one end of the magnetic fluid shaft.

[0014] Furthermore, the stage assembly also includes a circulating water cooling pipe fixedly connected to the sample stage. A sleeve is coaxially provided on the outside of the circulating water cooling pipe. The sleeve is fixedly connected to the cavity plate. A rack is fixedly provided on the outer wall of the sleeve. The rack is meshed with the gear.

[0015] The beneficial effects of this utility model are: This invention relates to a cavity structure for MPCVD equipment, incorporating an air-cooling structure and employing a combined water and air cooling method. A first water-cooling component and an air-cooling component are integrated within the microwave-connected cavity to reduce the temperature of the vacuum-sealed quartz glass, preventing it from being burned out by high temperatures. A first lifting device adjusts the height of the sample stage, ensuring the diamond substrate and diamond seed crystals on it are at a suitable height, allowing the microwaves and plasma to form a high-temperature "fireball" that evenly covers the substrate and seed crystals. A second lifting device, connected by a gear and rack mechanism, raises and lowers the cavity plate, adjusting the distance between the cavity plate and the vacuum-sealed quartz glass of the main reaction cavity. Reaction gases such as hydrogen and methane enter the main reaction cavity through a gas path. High-power 2450MHz microwaves penetrate the vacuum-sealed quartz glass, creating an electromagnetic field between the glass and the cavity plate. The ionization of hydrogen and plasma within this electromagnetic field, generated by the high-power microwaves, forms a high-temperature "fireball" on the molybdenum substrate at the sample stage along the cavity axis, providing a vacuum, high-temperature, and electromagnetic field environment for diamond deposition. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a three-dimensional structural diagram of the microwave cavity assembly of this utility model; Figure 4 This is a partial cross-sectional view of the microwave cavity assembly of this utility model; Figure 5 This is a three-dimensional structural diagram of the main cavity assembly of this utility model; Figure 6 This is a partial cross-sectional view of the main cavity assembly of this utility model; Figure 7 This is a three-dimensional structural diagram of the lower cavity assembly of this utility model; Figure 8 This is a partial cross-sectional view of the lower cavity assembly of this utility model; Figure 9 This is a cross-sectional view of the bellows assembly of this utility model; Figure 10 This is a three-dimensional structural diagram of the first lifting device of this utility model; Figure 11 This is a front view of the second lifting device of this utility model; Figure 12 This is a cross-sectional view of the stage assembly of this utility model; Figure 13 This is a three-dimensional structural diagram of the sample stage of this utility model.

[0017] Explanation of reference numerals in the attached figures: 1. Microwave cavity assembly; 11. First water-cooling assembly; 111. First water inlet pipe; 112. First water outlet pipe; 12. Air-cooling assembly; 121. Air inlet pipe; 122. Air outlet pipe; 13. Microwave connection cavity; 131. First outer cylinder; 132. First inner cylinder; 133. First water-cooling cavity; 14. First upper flange; 15. First lower flange; 2. Main cavity assembly; 21. Main reaction chamber; 211. Second outer cylinder; 212. Second inner cylinder; 213. Second water-cooled chamber; 22. Second upper flange; 23. Second lower flange; 24. Vacuum-sealed quartz glass; 25. Second water-cooling assembly; 251. Second water inlet pipe; 252. Second water outlet pipe; 26. Air inlet pipe; 27. Air supply port; 28. Feed sealing port; 29. ​​Observation window; 3. Lower cavity assembly; 31. Single-layer lower cavity; 32. Third upper flange; 33. Third lower flange; 34. Magnetohydrodynamic pipeline; 35. Vacuum pumping pipeline; 36. Vacuum gauge; 37. Air rupture pipeline; 4. Bellows assembly; 41. Welded bellows; 42. Fourth upper flange; 43. Fourth lower flange; 44. Pressure ring; 45. O-ring seal; 5. Stage assembly; 51. Sample stage; 511. Spiral water-cooled cavity; 52. Cavity plate; 53. Circulating water-cooled pipe; 54. Sleeve; 55. Rack; 56. Third water inlet pipe; 57. Third water outlet pipe; 6. First lifting device; 61. First motor reducer; 62. Motor support plate; 63. Ball screw; 64. Nut; 65. Fixed seat; 66. Guide rod; 67. Linear bearing; 7. Second lifting device; 71. Second motor reducer; 72. Magnetohydrodynamic shaft; 73. Gear. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Many specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] like Figures 1-2The diagram shows the cavity structure of the MPCVD equipment of this utility model, which includes a microwave cavity assembly 1, a main cavity assembly 2, a lower cavity assembly 3, and a bellows assembly 4 connected sequentially from top to bottom. The microwave cavity assembly 1 includes a first water-cooling assembly 11 and an air-cooling assembly 12. A stage assembly 5 is vertically mounted inside the main cavity assembly 2, the lower cavity assembly 3, and the bellows assembly 4. The stage assembly 5 includes a sample stage 51 and a cavity plate 52, which are slidably connected.

[0020] like Figure 3 and Figure 4 As shown, the microwave cavity assembly 1 includes a microwave connecting cavity 13. The microwave connecting cavity 13 adopts a double-layer water-cooled structure with inner and outer cylinders. Specifically, the microwave connecting cavity 13 includes a first outer cylinder 131 and a first inner cylinder 132 arranged coaxially, forming a first water-cooled cavity 133 between the first outer cylinder 131 and the first inner cylinder 132. A first upper flange 14 is fixedly connected to the top of the microwave connecting cavity 13, and a first lower flange 15 is fixedly connected to the bottom of the microwave connecting cavity 13. The first upper flange 14 is connected to a microwave source (not shown in the figure). In this embodiment, the microwave source provides a stable 2450MHz microwave for the deposition reaction in the equipment cavity, forming a stable and uniform electromagnetic field. A sealing groove is provided on the first lower flange 15, and a C-shaped sealing ring is provided in the sealing groove.

[0021] The microwave cavity assembly 1 includes a first water-cooling assembly 11 and an air-cooling assembly 12. The first water-cooling assembly 11 includes a first water inlet pipe 111 and a first water outlet pipe 112. The first water inlet pipe 111 is located below the first water outlet pipe 112. One end of the first water inlet pipe 111 and the first water outlet pipe 112 passes through the first outer cylinder 131 and is connected to the first water-cooling cavity 133. The outer walls of the first water inlet pipe 111 and the first water outlet pipe 112 are fixed to the first outer cylinder 131 by full welding to improve the tightness of the connection. The air-cooling assembly 12 includes two air inlet pipes 121 and multiple air outlet pipes 122. One end of the air inlet pipes 121 and the air outlet pipes 122 passes through the first outer cylinder 131 and the first inner cylinder 132 in sequence and is connected to the inner cavity of the first inner cylinder 132. The connections between the outer walls of the air inlet pipes 121 and the air outlet pipes 122 and the first inner cylinder 132 and the first outer cylinder 131 are all fixed by full welding. The air inlet pipe 121, air outlet pipe 122, first water inlet pipe 111, and first water outlet pipe 112 are all made of 316L stainless steel, which has the characteristics of corrosion resistance and high temperature resistance. In addition, it is non-magnetic (the relative magnetic permeability of 316L material is ≤1.02), so it will not affect the conduction of microwaves.

[0022] The inclined arrangement of the air inlet duct 121 allows cold air to enter the cavity at a certain angle, forming a jet that adheres to the heat source surface, reducing airflow separation from the wall and improving heat exchange efficiency. Multiple air outlet ducts 122 are horizontally arranged and evenly distributed along the circumference of the microwave-connected cavity 13. Multiple horizontal air outlets disperse the exhaust area, avoiding localized high-temperature accumulation caused by a single outlet. The air inlet duct 121 is located above the air outlet ducts 122, forming a vertical circulating flow field of "cold air sinking → hot air rising," reducing fan energy consumption. In this embodiment, two air inlet ducts 121 are arranged at 90 degrees along the circumference of the microwave-connected cavity 13. The vertical airflow direction naturally disperses the airflow, forming a "cross" coverage. The airflow forms a grid-like distribution in the horizontal plane, effectively covering corners and edges, reducing ventilation dead zones.

[0023] like Figure 5 and Figure 6 As shown, the main chamber assembly 2 includes a main reaction chamber 21, which is the main reaction chamber of the entire diamond MPCVD equipment. The main reaction chamber 21 adopts a double-layer water-cooled structure with inner and outer cylinders. That is, the main reaction chamber 21 includes a second outer cylinder 211 and a second inner cylinder 212 arranged coaxially, and a second water-cooled cavity 213 is formed between the second outer cylinder 211 and the second inner cylinder 212. A second upper flange 22 is fixedly connected to the top of the main reaction chamber 21, and the second upper flange 22 is fixedly connected to the first lower flange 15 of the microwave connection cavity 13. A second lower flange 23 is fixedly connected to the bottom of the main reaction chamber 21. A sealing groove is also provided on the second upper flange 22, and a C-shaped sealing ring is provided in the sealing groove. A vacuum-sealed quartz glass 24 is placed on top of the C-shaped sealing ring. The top of the vacuum-sealed quartz glass 24 abuts against the C-shaped sealing ring on the first lower flange 15. That is, the vacuum-sealed quartz glass 24 is sandwiched between the two C-shaped sealing rings and forms a vacuum seal with the main reaction chamber 21. Microwaves, through the microwave connecting cavity 13 and the lower vacuum-sealed quartz glass 24, provide an electromagnetic field to the main reaction cavity 21. Furthermore, the first water-cooling component 11 and the air-cooling component 12 installed within the microwave connecting cavity 13 are used to reduce the temperature of the vacuum-sealed quartz glass 24, preventing it from being burned out by high temperatures. In addition, the double-layered water-cooling structure of the microwave connecting cavity 13 and the main reaction cavity 21 increases the cooling water volume and allows for increased inlet pressure to increase the cooling water flow rate, thereby improving the cooling effect of the cavity and protecting the vacuum-sealed quartz glass 24 connected to the cavity.

[0024] The main reaction chamber 21 is connected to a second water inlet pipe 251, a second water outlet pipe 252, and an air inlet pipe 26. The second water inlet pipe 251 and the second water outlet pipe 252 constitute a second water-cooling assembly 25. The second water inlet pipe 251 is located below the second water outlet pipe 252 and is connected to the second water-cooling chamber 213. The second water-cooling assembly 25 allows cooling water to circulate within the main reaction chamber 21 to regulate the temperature inside the chamber and reduce the temperature of the outer cylinder.

[0025] Multiple gas supply holes 27 are provided on the main reaction chamber 21. The gas inlet pipe 26 is located at the lower part of the main reaction chamber 21, and the multiple gas supply holes 27 are located at the upper part of the main reaction chamber 21, and the multiple gas supply holes 27 are evenly distributed along the circumference of the main reaction chamber 21. The arrangement of the gas inlet pipe 26 and multiple gas supply holes 27 is used to allow the reaction gases such as hydrogen and methane to enter the main reaction chamber 21 through the gas path. High-power 2450MHz microwaves pass through the vacuum-sealed quartz glass 24, forming an electromagnetic field between the vacuum-sealed quartz glass 24 and the cavity plate 52 in the cavity. The ionization of hydrogen and plasma in the electromagnetic field generated by the high-power microwaves forms a high-temperature "fireball" through the molybdenum substrate at the sample stage 51 on the cavity axis, providing a vacuum, high temperature, and electromagnetic field environment for diamond deposition.

[0026] The main reaction chamber 21 is also equipped with a feeding sealing port 28 and an observation window 29. The feeding sealing port 28 is also equipped with a vacuum-sealed quartz glass 24 and a locking handwheel (not shown in the figure). All components are made of 316L stainless steel, which is resistant to high temperature and corrosion and is non-magnetic (the relative permeability of 316L material is ≤1.02), meeting both the requirements of high vacuum and the requirements of high temperature, corrosion resistance and non-magnetic reaction environment.

[0027] like Figure 7 and Figure 8 As shown, the lower cavity assembly 3 is sealed to the main reaction chamber 21 and the bellows assembly 4, serving as a connecting link. The lower cavity assembly 3 includes a single-layer lower cavity 31, with a third upper flange 32 fixedly connected to the top and a third lower flange 33 fixedly connected to the bottom. The third upper flange 32 is fixedly connected to the second lower flange 23, and the third lower flange 33 is connected to the lower bellows assembly 4. The outer periphery of the single-layer lower cavity 31 is connected to a magnetohydrodynamic pipeline 34 and a vacuum pumping pipeline 35, and a vacuum gauge 36 is also provided. The vacuum pumping pipeline 35 is connected to a vacuum pump to evacuate the vacuum, and the vacuum gauge 36 is used to measure the vacuum level of the cavity. The single-layer lower cavity 31 is also equipped with a venting pipe 37, which vents the entire cavity to restore atmospheric pressure after the equipment has completed testing or production. The single-layer lower cavity 31 is made of 304 stainless steel, which meets the requirements of high vacuum equipment. At the same time, 304 stainless steel is also resistant to high temperature and high corrosion, as well as has a low relative permeability, so it will not affect the electromagnetic field of the main reaction cavity 21.

[0028] like Figure 9 The bellows assembly 4 is shown. The bellows assembly 4 includes a welded bellows 41. A fourth upper flange 42 is fixedly installed on the top of the welded bellows 41, and a fourth lower flange 43 is fixedly installed on the bottom of the welded bellows 41. The fourth upper flange 42 is vacuum-sealed to the third lower flange 33 at the bottom of the single-layer lower cavity 31. The fourth lower flange 43 has a pressure ring 44 and a fluororubber O-ring 45.

[0029] A stage assembly 5 is vertically mounted within the main cavity assembly 2, lower cavity assembly 3, and bellows assembly 4. The stage assembly 5 primarily supports the diamond growth substrate and seed crystals, and also serves for cooling and temperature regulation. The stage assembly 5 includes a sample stage 51 and a cavity plate 52, which are slidably connected. Figure 10 As shown, the sample stage 51 is slidably connected to the main cavity assembly 2 via a first lifting device 6. The first lifting device 6 includes a first motor reducer 61 fixedly mounted on the lower cavity assembly 3. Specifically, the first motor reducer 61 consists of a servo motor and a right-angle reducer. The first motor reducer 61 is fixedly mounted on a motor support plate 62, which is fixedly connected to the single-layer lower cavity 31. A ball screw 63 is fixedly connected to the output shaft of the first motor reducer 61. A nut 64 is threaded onto the outer side of the ball screw 63. A fixing seat 65 is fixedly connected to the nut 64. The fourth lower flange 43 at the bottom of the bellows assembly 4 is fixedly connected to both the fixing seat 65 and the sample stage 51. Specifically, the fourth lower flange 43 of the bellows assembly 4 is fixed to the fixing seat 65 by screws and then vacuum-sealed to the stage assembly 5 by a pressure ring 44 and a fluororubber O-ring 45. The sample stage 51 is fixedly connected to the bottom of the welded bellows 41. When the first lifting device 6 moves the sample stage 51 up and down, it also moves the fourth lower flange 43 of the bellows assembly 4 up and down, thereby adjusting the height of the sample stage 51. The fixed seat 65 is provided with multiple guide rods 66, and the guide rods 66 are fitted with linear bearings 67 to guide and ensure that the fixed seat 65 moves back and forth along the axial direction of the ball screw 63.

[0030] The first motor reducer 61 is started, which drives the ball screw 63 to rotate. Due to the setting of multiple guide rods 66, the rotation of the ball screw 63 drives the nut 64 and the fixed seat 65 to move along their axial direction, so as to adjust the rise and fall of the sample stage 51 fixedly connected to the fixed seat 65, so that the diamond substrate and the diamond seed crystal on the sample stage 51 are at a suitable height, so that the microwave and plasma can form a high temperature "fireball" and the formed high temperature "fireball" evenly covers the substrate and the seed crystal.

[0031] like Figures 11-13As shown, the cavity plate 52 is slidably connected to the sample stage 51 via the second lifting device 7. The second lifting device 7 includes a second motor reducer 71, which consists of a servo motor and a reducer. A magnetofluid shaft 72 is fixedly connected to the output shaft of the second motor reducer 71. The magnetofluid shaft 72 passes through the magnetofluid pipeline 34 of the single-layer lower cavity 31 and is connected to the single-layer lower cavity 31 in a high-vacuum metal-sealed connection. A gear 73 is fixedly provided at one end of the magnetofluid shaft 72, and the gear 73 is located in the inner cavity of the single-layer lower cavity 31.

[0032] The stage assembly 5 also includes a circulating water cooling pipe 53 fixedly connected to the sample stage 51. A sleeve 54 is coaxially provided on the outer side of the circulating water cooling pipe 53. The sleeve 54 is fixedly connected to the cavity plate 52. A rack 55 is fixedly provided on the outer wall of the sleeve 54. The rack 55 is meshed with a gear 73. A servo motor drives the magnetofluid shaft 72 to rotate through a reducer. The gear 73 at the front end of the magnetofluid shaft 72 is connected to the cavity plate 52 through a gear and rack. The forward and reverse rotation of the gear 73 drives the cavity plate 52, which is welded to the rack 55, to move up and down, adjusting the distance between the cavity plate 52 and the vacuum-sealed quartz glass 24 of the main reaction chamber 21. A spiral water cooling cavity 511 is provided at the bottom of the sample stage 51. A third water inlet pipe 56 and a third water outlet pipe 57 are also connected to the circulating water cooling pipe 53. The third water inlet pipe 56 is connected to the spiral water cooling cavity to cool the sample stage 51.

[0033] The cavity structure of this utility model for MPCVD equipment adjusts the height of the sample stage 51 via a first lifting device 6, ensuring that the diamond substrate and diamond seed crystals on the sample stage 51 are at a suitable height. This allows microwaves and plasma to form a high-temperature "fireball," which uniformly covers the substrate and seed crystals. A second lifting device 7, connected by a gear and rack, moves the cavity plate 52, adjusting the distance between the cavity plate 52 and the vacuum-sealed quartz glass 24 of the main reaction cavity 21. Reaction gases such as hydrogen and methane enter the main reaction cavity 21 through a gas path. High-power 2450MHz microwaves pass through the vacuum-sealed quartz glass 24, creating an electromagnetic field between the vacuum-sealed quartz glass 24 and the cavity plate 52. The ionized hydrogen and plasma, within the electromagnetic field generated by the high-power microwaves, form a high-temperature "fireball" on the molybdenum substrate at the sample stage 51 along the cavity axis, providing a vacuum, high-temperature, and electromagnetic field environment for diamond deposition. The first water-cooling component 11 and the air-cooling component 12 installed inside the microwave connection cavity 13 are used to reduce the temperature of the vacuum-sealed quartz glass 24 and prevent it from being burned by high temperature.

[0034] While this utility model discloses preferred embodiments to achieve the above objectives, it is not intended to limit the structural features of this utility model. Anyone skilled in the art should know that any easily conceivable variations or modifications are possible under the technical spirit of this utility model and are covered by the patent claims of this utility model.

Claims

1. A cavity structure for an MPCVD device, characterized in that, The device includes a microwave cavity assembly (1), a main cavity assembly (2), a lower cavity assembly (3), and a bellows assembly (4) connected sequentially from top to bottom. The microwave cavity assembly (1) includes a first water-cooling assembly (11) and an air-cooling assembly (12). A stage assembly (5) is vertically mounted inside the main cavity assembly (2), the lower cavity assembly (3), and the bellows assembly (4). The stage assembly (5) includes a sample stage (51) and a cavity plate (52). The sample stage (51) and the cavity plate (52) are slidably connected.

2. The cavity structure for MPCVD equipment according to claim 1, characterized in that, The microwave cavity assembly (1) includes a microwave connecting cavity (13), which includes a first outer cylinder (131) and a first inner cylinder (132) arranged coaxially. A first water-cooled cavity (133) is formed between the first outer cylinder (131) and the first inner cylinder (132). A first upper flange (14) is fixedly connected to the top of the microwave connecting cavity (13), and a first lower flange (15) is fixedly connected to the bottom of the microwave connecting cavity (13).

3. The cavity structure for MPCVD equipment according to claim 2, characterized in that, The first water-cooling assembly (11) includes a first water inlet pipe (111) and a first water outlet pipe (112). The first water inlet pipe (111) is located below the first water outlet pipe (112). One end of the first water inlet pipe (111) and the first water outlet pipe (112) passes through the first outer cylinder (131) and is connected to the first water-cooling cavity (133).

4. The cavity structure for MPCVD equipment according to claim 2, characterized in that, The air-cooled assembly (12) includes two air inlet pipes (121) and multiple air outlet pipes (122). One end of each air inlet pipe (121) and air outlet pipe (122) passes through the first outer cylinder (131) and the first inner cylinder (132) in sequence, and is connected to the inner cavity of the first inner cylinder (132). The air inlet pipe (121) is inclined, and the air outlet pipe (122) is horizontal.

5. The cavity structure for an MPCVD device according to claim 2 or 3, characterized in that, The main cavity assembly (2) includes a main reaction cavity (21), which includes a second outer cylinder (211) and a second inner cylinder (212) arranged coaxially. A second water-cooled cavity (213) is formed between the second outer cylinder (211) and the second inner cylinder (212). A second upper flange (22) is fixedly connected to the top of the main reaction cavity (21), and the second upper flange (22) is fixedly connected to the first lower flange (15). A second lower flange (23) is fixedly connected to the bottom of the main reaction cavity (21).

6. The cavity structure for an MPCVD device according to claim 5, characterized in that, The main reaction chamber (21) is connected to a second water inlet pipe (251), a second water outlet pipe (252) and an air inlet pipe (26), and the main reaction chamber (21) is provided with multiple air supply holes (27).

7. The cavity structure for MPCVD equipment according to claim 1, characterized in that, The lower cavity assembly (3) includes a single-layer lower cavity (31), the top of which is fixedly connected to a third upper flange (32), the bottom of which is fixedly connected to a third lower flange (33), and the outer periphery of the single-layer lower cavity (31) is connected to a magnetohydrodynamic pipeline (34) and a vacuum pumping pipeline (35).

8. The cavity structure for an MPCVD device according to claim 1, characterized in that, The sample stage (51) is slidably connected to the main cavity assembly (2) via a first lifting device (6). The first lifting device (6) includes a first motor reducer (61) fixedly mounted on the lower cavity assembly (3). A ball screw (63) is fixedly connected to the output shaft of the first motor reducer (61). A nut (64) is threaded onto the outer side of the ball screw (63). A fixed seat (65) is fixedly connected to the nut (64). The bottom of the bellows assembly (4) is fixedly connected to the fixed seat (65) and the sample stage (51).

9. The cavity structure for an MPCVD device according to claim 1, characterized in that, The cavity plate (52) is slidably connected to the sample stage (51) via the second lifting device (7). The second lifting device (7) includes a second motor reducer (71). A magnetohydrodynamic shaft (72) is fixedly connected to the output shaft of the second motor reducer (71). A gear (73) is fixedly provided at one end of the magnetohydrodynamic shaft (72).

10. The cavity structure for an MPCVD device according to claim 9, characterized in that, The stage assembly (5) also includes a circulating water cooling pipe (53) fixedly connected to the sample stage (51). A sleeve (54) is coaxially provided on the outside of the circulating water cooling pipe (53). The sleeve (54) is fixedly connected to the cavity plate (52). A rack (55) is fixedly provided on the outer wall of the sleeve (54). The rack (55) is meshed with the gear (73).

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