CN115717237A

CN115717237A - Plasma CVD apparatus with superconducting magnet

Info

Publication number: CN115717237A
Application number: CN202211313351.9A
Authority: CN
Inventors: 徐晰人; 金国辉; 杨晓亮
Original assignee: New Advantage Industry Group Co ltd
Current assignee: New Advantage Industry Group Co ltd
Priority date: 2022-10-25
Filing date: 2022-10-25
Publication date: 2023-02-28

Abstract

The invention discloses a superconducting magnet arranged on the top of a cavity of a plasma CVD device with the superconducting magnet, wherein the superconducting magnet comprises a superconducting coil and a low-temperature device which are connected with a variable-frequency power supply, the upper end of the superconducting coil is cylindrical, the lower end of the superconducting coil is expanded outwards to form a horn shape with a small upper part and a big lower part, and an insulating top plate is arranged between the cavity and the superconducting magnet; a base material table is arranged in the cavity, an insulating ring is arranged between the base material table and a bottom plate of the cavity, and a microwave input hole is formed in the center of the bottom plate on the inner side of the insulating ring; the microwave generator is connected with the cavity through the mode converter and the microwave input hole, and one side of the cavity is provided with a cavity lifting device. In the plasma CVD device, carbon in the plasma can be deposited downwards and transversely, so that the plasma CVD device is suitable for the base material with a three-dimensional structure, and the application range of the CVD device is greatly expanded.

Description

Plasma CVD apparatus with superconducting magnet

Technical Field

The invention belongs to the technical field of chemical vapor deposition equipment, and particularly relates to a plasma CVD device with a superconducting magnet.

Background

Chemical Vapor Deposition (CVD) is widely used for diamond synthesis, in which a mixture of gases (hydrogen, oxygen, nitrogen, methane, etc.) is heated in a chamber to form a carbon plasma in the chamber, and the carbon in the plasma is continuously deposited on a substrate (carbon substrate) in the chamber, and gradually accumulates and hardens to form a diamond layer. In the prior art plasma CVD device, carbon in the plasma can only be deposited downwards and a diamond thin layer is formed on the upper surface of the substrate, and the plasma CVD device is only suitable for the substrate with a plane structure and cannot perform surface deposition on the substrate with a three-dimensional structure, thereby severely limiting the application range of the CVD device. The publication date is 2022, 1 month, 11 days, and the publication number is CN113913780A, which discloses a plasma CVD apparatus, wherein the chamber includes an inner chamber enclosed by a bottom plate, a side wall and a top cover, a side wall cooling chamber is arranged in the side wall, a uniform air inlet device is arranged on the top cover, a uniform exhaust device is arranged on the bottom plate, a platform for placing a substrate is arranged at the lower part of the inner chamber, a platform cooling chamber is arranged in the platform, a microwave source on a rack is connected with a waveguide coaxial conversion device, a coaxial output end outer conductor of the waveguide coaxial conversion device is connected with a microwave input hole on the bottom plate, an inner conductor is connected with an opening at the bottom of the platform cooling chamber, and a cooling liquid input pipe is sleeved in the inner conductor. However, in the plasma CVD apparatus, carbon in the plasma can only be deposited downward on the upper surface of the substrate to form a diamond thin layer, and the substrate with a three-dimensional structure cannot be surface-deposited, which severely limits the applicable scope of the CVD apparatus.

Disclosure of Invention

The invention aims to solve the problems that the plasma CVD device in the prior art is only suitable for a substrate with a planar structure, cannot carry out surface deposition on the substrate with a three-dimensional structure and seriously limits the application range of the CVD device.

The invention adopts the technical scheme that the plasma CVD device with the superconducting magnet comprises a rack and a cavity, wherein the cavity comprises a bottom plate and a cylindrical cavity wall arranged on the bottom plate, the top of the cavity is provided with the superconducting magnet, the superconducting magnet comprises a superconducting coil and a low-temperature device arranged on the periphery of the superconducting coil, the superconducting coil is connected with a variable-frequency power supply, the upper end of the superconducting coil is cylindrical, the lower end of the superconducting coil is outwards expanded to form a horn shape with a small upper part and a large lower part, and the cavity and the superconducting magnet are separated by an insulating top plate arranged on the top of the cavity; a base material table is arranged in the cavity, an insulating ring is arranged between the base material table and a bottom plate of the cavity, and a microwave input hole is formed in the center of the bottom plate on the inner side of the insulating ring; the microwave generator arranged on the frame is connected with the cavity through the mode converter and the microwave input hole, and one side of the cavity is provided with a cavity lifting device which is connected with the cylindrical cavity wall of the cavity.

The superconducting magnet is arranged on the top of a cavity of a CVD device, the superconducting magnet comprises a superconducting coil for generating a strong magnetic field and a low-temperature device arranged on the periphery of the superconducting coil, the lower end of the superconducting coil is expanded outwards to form a horn shape with a small upper part and a large lower part, the superconducting coil is connected with a variable-frequency power supply, the output frequency of the variable-frequency power supply is adjustable, an alternating strong magnetic field generated by the superconducting coil enters the cavity through an insulating top plate on the top of the cavity and interacts with an electromagnetic field generated by microwaves in the cavity to form a vortex-shaped strong magnetic field with continuously changed direction in the cavity, the moving direction of carbon in plasma in the cavity is changed, carbon in the plasma in the cavity can be deposited downwards and transversely, the state of the plasma in the cavity is in a stable working state by adjusting the current and the frequency on the superconducting coil, the external surface deposition requirement of a substrate with a three-dimensional structure is met, the problem that the CVD device in the prior art is only suitable for a substrate with a planar structure, the surface deposition of the CVD device cannot be carried out, the CVD device application range of the CVD device is seriously limited, and the CVD device is greatly expanded.

Preferably, a magnetic field adjusting rod is coaxially arranged in the center of the superconducting coil, the magnetic field adjusting rod is of a hollow structure, an air inlet is formed in the top end of the magnetic field adjusting rod, the bottom end of the magnetic field adjusting rod is located in a conical cavity in the bottom of the superconducting magnet, and a plurality of air outlets are formed in the periphery of the bottom of the superconducting magnet. The magnetic field adjusting rod is used for finely adjusting the magnetic field, the material of the magnetic field adjusting rod is brass, the shape of the magnetic field in the cavity can be adjusted by adjusting the entering amount of the magnetic field adjusting rod and matching with the adjustment of the current and the frequency on the superconducting coil, and the optimal effect of performing surface deposition on the substrate with a three-dimensional structure is achieved. And an air inlet at the top end of the magnetic field adjusting rod is used for allowing cold air to enter the conical cavity at the bottom of the superconducting coil for heat dissipation.

Preferably, an insulating partition plate is arranged between the bottom of the superconducting magnet and an insulating top plate at the top of the cavity, a through hole is formed in the center of the insulating partition plate, an air outlet cavity is formed between the insulating partition plate and the insulating top plate, and the air outlet is formed in the wall of the air outlet cavity.

Preferably, the low-temperature device comprises a cooling jacket surrounding the superconducting coil, low-temperature cooling liquid is arranged in the cooling jacket, a low-temperature cooling liquid inlet and outlet is formed in the top end of the cooling jacket, and the low-temperature cooling liquid is liquid helium. The low-temperature device provides a low-temperature environment for the superconducting coil and ensures that the coil works in a superconducting state.

Preferably, the output frequency range of the variable frequency power supply is 15-270Hz, and the magnetic induction intensity generated by the superconducting coil at the center of the cavity is 2-5 Tesla.

Preferably, the cavity lifting device is arranged on the bottom plate and comprises a lifting frame and a lifting seat, a screw rod is arranged on the lifting frame, the top of the screw rod is connected with a lifting motor, a screw rod nut matched with the screw rod is arranged on the lifting seat, and the lifting seat is fixedly connected with the side wall of the cavity through a connecting rod. The cavity lifting device is used for lifting the cavity and meets the opening and closing requirements of the CVD device on the cavity during working.

As preferred, the lift seat includes frame and buffer block, and the vertical slide bar that is equipped with on the frame, buffer block pass through the sliding sleeve setting at the middle part of slide bar, and the cover is equipped with buffer spring on the slide bar of both sides about the sliding sleeve, buffer spring one end and sliding sleeve butt, the other end and frame butt, and screw-nut fixes on buffer block, and the connecting rod is fixed on the frame. The screw rod nut is fixed on the buffer block, the buffer block is arranged on the sliding rod through the sliding sleeve, and the sliding rods on the upper side and the lower side of the sliding sleeve are sleeved with the buffer springs; when the cavity is opened, the lifting mechanism exerts upward opening force on the cavity through the buffer spring on the upper side of the sliding sleeve, and the opening of the cavity can be buffered.

Preferably, the mode converter is of a cross structure and comprises two waveguide interfaces and two coaxial interfaces, the microwave generator is connected with the mode converter through a waveguide three-screw tuner, a waveguide short-circuit section is arranged on one side, opposite to the microwave generator, of the mode converter, an outer conductor of a coaxial output end of the mode converter is connected with a microwave input hole in the bottom plate, an inner conductor of the coaxial output end penetrates through the microwave input hole to be connected with the base material table, a coaxial short-circuit section is arranged on one side, opposite to the coaxial output end, of the coaxial output end, and a conical surface is arranged on the upper edge of the microwave input hole. The invention adopts a coaxial input mode to replace a waveguide probe input mode commonly adopted in the prior art, and the substrate table is equivalent to a microwave radiation unit, so that a microwave field is concentrated near the substrate table, the efficiency can be improved, the vertical height of the cavity is greatly shortened, and the volume of the cavity is reduced.

Preferably, the inner conductor of the coaxial output end is of a hollow structure, the inner conductor is internally sleeved with a cooling water input pipe, a cooling water output channel is formed between the inner wall of the inner conductor and the outer wall of the cooling water input pipe, a substrate table cooling cavity is arranged inside the substrate table, an opening is formed in the bottom of the cooling cavity, the inner conductor of the coaxial output end penetrates through the microwave input hole to be connected with the opening in the bottom of the cooling cavity, the upper end of the cooling water input pipe is located in the substrate table cooling cavity, and an annular diffusion plate is arranged at the top end of the cooling water input pipe. The substrate table is provided with the substrate table cooling cavity, and the inner conductor of the microwave input element with a hollow structure is used as the inlet and outlet channel of cooling water of the substrate table, so that the substrate table in the cavity can be sufficiently cooled, and the cooling effect of the substrate table is greatly improved; in addition, the annular diffusion plate is arranged at the top end of the cooling water input pipe, so that the input cooling water can be ensured to be firstly contacted with the top of the cooling cavity of the substrate table, and the cooling effect of the upper part (the position where the substrate is placed) of the substrate table is improved.

Preferably, the cavity wall is of a double-layer structure, an annular water cooling cavity is formed between the two layers of cavity walls, and an observation hole and a temperature measuring hole which penetrate through the cavity wall are further formed in the cavity wall; the air inlet of cavity sets up on the chamber wall of cavity top periphery, and the inlet port communicates with the diffusion channel that admits air that encircles the chamber wall setting, and air inlet joint connects on the diffusion channel that admits air, and the exhaust hole of cavity sets up on the chamber wall of cavity bottom periphery, and the exhaust hole communicates with the collecting channel that encircles the chamber wall setting, and exhaust articulate is on the collecting channel. The annular water-cooling cavity is used for cooling the cavity; the observation hole is used for observing the deposition condition on the substrate in the cavity and is horizontally or obliquely arranged; the temperature measuring hole is used for arranging a temperature probe and detecting the working temperature in the cavity to ensure that the temperature in the cavity meets the process requirement of chemical vapor deposition. The air inlet hole is communicated with the air inlet diffusion groove arranged around the cavity wall, so that the mixed gas entering the cavity can be uniformly dispersed into the air inlet diffusion groove and uniformly enters the inner cavity through the air inlet hole, and the uniform distribution of the mixed gas in the cavity is ensured. When exhausting, the gas in the cavity enters the gas collecting groove through the uniformly distributed exhaust holes and is then exhausted from the exhaust port in a centralized manner.

The invention has the beneficial effects that: the plasma CVD device effectively solves the problems that the plasma CVD device in the prior art is only suitable for a substrate with a plane structure, cannot carry out surface deposition on the substrate with a three-dimensional structure and seriously limits the application range of the CVD device.

Drawings

FIG. 1 is a cross-sectional view of a plasma CVD apparatus having a superconducting magnet according to the present invention;

FIG. 2 is a sectional view of a partial structure of a chamber according to the present invention;

FIG. 3 is a partial cross-sectional view of the mode converter and substrate table of the present invention;

FIG. 4 is a structural cross-sectional view of a superconducting magnet of the present invention;

FIG. 5 is a cross-sectional view of one construction of the lift device of the present invention;

figure 6 is a cross-sectional view of one configuration of the microwave channel of the present invention.

In the figure: 1. a frame, 2 cavity bodies, 3 bottom plate, 4 cavity walls, 5 superconducting magnets, 6 superconducting coils, 7 cryogenic device, 8 insulating top plate, 9 base material table, 10 insulating ring, 11 microwave input hole, 12 microwave generator, 13 mode converter, 14 cavity lifting device, 15 magnetic field adjusting rod, 16 air inlet, 17 conical cavity, 18 air outlet, 19 insulating partition plate, 20 air outlet cavity, 21 cooling jacket, 22 cryogenic cooling liquid, 23 cryogenic cooling liquid inlet and outlet, 24 lifting frame, 25 screw rod, 26 lifting motor, 27 screw rod nut, 28 connecting rod, 29, a frame, 30, a buffer block, 31, a sliding rod, 32, a sliding sleeve, 33, a buffer spring, 34, a three-screw adapter, 35, a waveguide short-circuit section, 36, an inner conductor, 37, a coaxial short-circuit section, 38, a conical surface, 39, a cooling water input pipe, 40, a cooling water output channel, 41, a base material table cooling cavity, 42, an annular diffusion plate, 43, an observation hole, 44, an air inlet hole, 45, an air inlet diffusion groove, 46, an air inlet joint, 47, an air outlet hole, 48, an air collecting groove, 49, a sealing ring, 50, a waveguide pipe, 51, a through hole, 52, an annular water cooling cavity, 53, a water inlet and 54, a water outlet.

Detailed Description

The following provides a further description of embodiments of the present invention by way of examples and with reference to the accompanying drawings.

Example 1

In embodiment 1 shown in fig. 1, a plasma CVD apparatus with a superconducting magnet includes a rack 1 and a cavity 2, the cavity includes a bottom plate 3 and a cylindrical cavity wall 4 disposed on the bottom plate, the cavity wall is a double-layer structure, an annular water cooling cavity 52 (see fig. 2) is formed between the two cavity walls, and the annular water cooling cavity is connected with a water inlet 53 and a water outlet 54 respectively; the cavity wall is also provided with an observation hole 43 and a temperature measuring hole which penetrate through the cavity wall; the air inlet hole 44 of the cavity is arranged on the cavity wall at the periphery of the top of the cavity, the air inlet hole is communicated with the air inlet diffusion groove 45 arranged around the cavity wall, the air inlet joint 46 is connected on the air inlet diffusion groove, the air outlet hole 47 of the cavity is arranged on the cavity wall at the periphery of the bottom of the cavity, the air outlet hole is communicated with the air collecting groove 48 arranged around the cavity wall, and air is discharged through the air collecting groove. The annular water-cooling cavity is used for cooling the cavity; the observation hole is used for observing the deposition condition on the substrate in the cavity and is horizontally or obliquely arranged; the temperature measuring hole is used for arranging a temperature probe and detecting the working temperature in the cavity to ensure that the temperature in the cavity meets the process requirement of chemical vapor deposition. The air inlet hole is communicated with the air inlet diffusion groove arranged around the cavity wall, so that the mixed gas entering the cavity can be uniformly dispersed into the air inlet diffusion groove and uniformly enters the inner cavity through the air inlet hole, and the uniform distribution of the mixed gas in the cavity is ensured. When exhausting, the gas in the cavity enters the gas collecting groove through the uniformly distributed exhaust holes and is then exhausted from the exhaust port in a centralized manner.

The top of cavity is equipped with superconducting magnet 5 (see fig. 4), and superconducting magnet includes superconducting coil 6 and sets up the low temperature equipment 7 in the superconducting coil periphery, and low temperature equipment is including the cooling jacket 21 that encircles superconducting coil, and the cooling jacket adopts stainless steel material, is equipped with cryogenic cooling liquid 22 in the cooling jacket, and the top of cooling jacket is equipped with two cryogenic cooling liquid's exit 23, and cryogenic cooling liquid is liquid helium. The low-temperature device provides a low-temperature environment for the superconducting coil and ensures that the coil works in a superconducting state.

The superconducting coil is connected with a variable frequency power supply (not shown in the figure), the output frequency range of the variable frequency power supply is 15-270Hz (adjustable), the upper end of the superconducting coil is cylindrical, the lower end of the superconducting coil is expanded outwards to form a horn shape with a small upper part and a big lower part, and the magnetic induction intensity generated by the superconducting coil in the center of the cavity is 2-5 Tesla (adjustable); the cavity and the superconducting magnet are separated by an insulating top plate 8 arranged at the top of the cavity, the insulating top plate is made of quartz glass, and a sealing ring 49 is arranged between the insulating top plate and the cavity; a substrate table 9 is arranged in the cavity, an insulating ring 10 is arranged between the substrate table and a bottom plate of the cavity, the insulating ring is made of quartz glass, sealing rings are arranged between the upper end and the lower end of the insulating ring and between the substrate table and the bottom plate respectively, and a microwave input hole 11 is formed in the center of the bottom plate; a microwave generator 12 arranged on the frame generates high-power microwave of 2450MHz, and is connected with the cavity (enters the cavity) through a waveguide-coaxial mode converter 13 and a microwave input hole.

The center of the superconducting coil is coaxially provided with a magnetic field adjusting rod 15 for finely adjusting a magnetic field, the magnetic field adjusting rod is of a hollow structure and made of brass, and the shape of the magnetic field in the cavity can be adjusted by adjusting the entering amount of the magnetic field adjusting rod and matching with the adjustment of the current and the frequency on the superconducting coil, so that the best effect of performing surface deposition on a substrate of a three-dimensional structure is achieved. The top end of the magnetic field adjusting rod is provided with an air inlet 16 for cold air to enter the conical cavity at the bottom of the superconducting coil for heat dissipation, the bottom end of the magnetic field adjusting rod is positioned in the conical cavity 17 at the bottom of the superconducting magnet, and the periphery of the bottom of the superconducting magnet is provided with a plurality of air outlets 18; an insulating partition plate 19 is arranged between the bottom of the superconducting magnet and an insulating top plate at the top of the cavity, the insulating partition plate is made of quartz glass, a through hole 51 is formed in the center of the insulating partition plate, an air outlet cavity 20 is formed between the insulating partition plate and the insulating top plate, and an air outlet is formed in the wall of the air outlet cavity.

A cavity lifting device 14 (shown in figure 5) is arranged on one side of the cavity and is connected with the cylindrical cavity wall of the cavity; the cavity lifting device is arranged on the bottom plate and comprises a lifting frame 24 and a lifting seat, a screw rod 25 is arranged on the lifting frame, the top of the screw rod is connected with a lifting motor 26, a screw rod nut 27 matched with the screw rod is arranged on the lifting seat, and the lifting seat is fixedly connected with the side wall of the cavity through a connecting rod 28. The lifting seat comprises a frame 29 and a buffer block 30, a sliding rod 31 is vertically arranged on the frame, the buffer block is arranged in the middle of the sliding rod through a sliding sleeve 32, a buffer spring 33 is sleeved on the sliding rod on the upper side and the lower side of the sliding sleeve, one end of the buffer spring is abutted against the sliding sleeve, the other end of the buffer spring is abutted against the frame, a screw nut is fixed on the buffer block, and a connecting rod is fixed on the frame. The cavity lifting device is used for lifting the cavity, and meets the opening and closing requirements of the CVD device on the cavity during working; the screw rod nut is fixed on the buffer block, the buffer block is arranged on the sliding rod through the sliding sleeve, and the sliding rods on the upper side and the lower side of the sliding sleeve are sleeved with the buffer springs; when the cavity is opened, the lifting mechanism exerts upward opening force on the cavity through the buffer spring on the upper side of the sliding sleeve, and the opening of the cavity can be buffered.

The mode converter is a cross structure (see fig. 3 and fig. 6), and comprises two waveguide interfaces and two coaxial interfaces, wherein a microwave generator is connected with the mode converter through a WR-340 waveguide tube 50 and a waveguide three-screw tuner 34, a waveguide short-circuit section 35 is arranged on one side of the mode converter opposite to the microwave generator, an outer conductor of a coaxial output end of the mode converter is connected with a microwave input hole on a bottom plate, an inner conductor 36 of the coaxial output end penetrates through the microwave input hole to be connected with a base material table, a coaxial short-circuit section 37 is arranged on one side opposite to the coaxial output end, and a conical surface 38 is arranged on the upper edge of the microwave input hole. The invention adopts a coaxial input mode to replace a waveguide probe input mode generally adopted in the prior art, and the substrate table is equivalent to a radiation unit of microwave, so that a microwave field is concentrated near the substrate table, the efficiency can be improved, the vertical height of a cavity is greatly shortened, and the volume of the cavity is reduced.

The inner conductor of coaxial output end is hollow structure, the inner conductor endotheca is equipped with cooling water input tube 39, constitute cooling water output channel 40 between the inner wall of inner conductor and the outer wall of cooling water input tube, the inside of substrate platform is equipped with substrate platform cooling chamber 41, the bottom in cooling chamber is equipped with the opening, the inner conductor of coaxial output end passes microwave input hole and links to each other with the opening of cooling chamber bottom, the upper end of cooling water input tube is located substrate platform cooling chamber, the top of cooling water input tube is equipped with annular diffuser plate 42. The substrate table is provided with the substrate table cooling cavity, and the inner conductor of the microwave input element with a hollow structure is used as the inlet and outlet channel of cooling water of the substrate table, so that the substrate table in the cavity can be sufficiently cooled, and the cooling effect of the substrate table is greatly improved; in addition, the annular diffusion plate is arranged at the top end of the cooling water input pipe, so that the input cooling water can be ensured to be firstly contacted with the top of the cooling cavity of the substrate table, and the cooling effect of the upper part (the position where the substrate is placed) of the substrate table is improved. During operation, cooling water enters from the inner hole of the cooling water input pipe, enters the base material table cooling cavity through the annular diffusion plate, and is discharged through a drainage channel between the outer wall of the cooling water input pipe and the inner wall of the inner conductor after the base material table is cooled (not shown in the figure).

In addition to the above embodiments, technical features or technical data of the present invention may be reselected and combined to form a new embodiment within the scope of the claims of the present invention and the specification, which is achieved without creative efforts of those skilled in the art, and thus, the embodiments of the present invention not described in detail should be regarded as specific embodiments of the present invention and are within the scope of protection of the present invention.

Claims

1. A plasma CVD device with a superconducting magnet comprises a rack (1) and a cavity (2), wherein the cavity comprises a bottom plate (3) and a cylindrical cavity wall (4) arranged on the bottom plate, and is characterized in that the superconducting magnet (5) is arranged at the top of the cavity and comprises a superconducting coil (6) and a low-temperature device (7) arranged on the periphery of the superconducting coil, the superconducting coil is connected with a variable-frequency power supply, the upper end of the superconducting coil is cylindrical, the lower end of the superconducting coil is expanded outwards to form a horn shape with a small upper part and a large lower part, and the cavity and the superconducting magnet are separated by an insulating top plate (8) arranged at the top of the cavity; a base material table (9) is arranged in the cavity, an insulating ring (10) is arranged between the base material table and a bottom plate of the cavity, and a microwave input hole (11) is formed in the center of the bottom plate on the inner side of the insulating ring; a microwave generator (12) arranged on the machine frame is connected with the cavity through a mode converter (13) and a microwave input hole, a cavity lifting device (14) is arranged on one side of the cavity, and the cavity lifting device is connected with the cylindrical cavity wall of the cavity.

2. A plasma CVD apparatus with a superconducting magnet according to claim 1, wherein a magnetic field adjusting rod (15) is coaxially disposed in the center of the superconducting coil, the magnetic field adjusting rod is a hollow structure, an air inlet (16) is disposed at the top end of the magnetic field adjusting rod, the bottom end of the magnetic field adjusting rod is located in a conical cavity (17) at the bottom of the superconducting magnet, and a plurality of air outlets (18) are disposed at the periphery of the bottom of the superconducting magnet.

3. A plasma CVD apparatus with superconducting magnet according to claim 2, wherein an insulating partition plate (19) is disposed between the bottom of the superconducting magnet and the insulating top plate on the top of the chamber, a through hole (51) is disposed in the center of the insulating partition plate, an air outlet chamber (20) is formed between the insulating partition plate and the insulating top plate, and the air outlet is disposed on the wall of the air outlet chamber.

4. A plasma CVD apparatus with a superconducting magnet according to claim 1, wherein the cryo apparatus includes a cooling jacket (21) surrounding the superconducting coil, a cryo-cooling fluid (22) is provided in the cooling jacket, a cryo-cooling fluid inlet and outlet (23) is provided at a top end of the cooling jacket, and the cryo-cooling fluid is liquid helium.

5. A plasma CVD apparatus with a superconducting magnet according to claim 1, wherein the output frequency of the variable frequency power supply is in a range of 15 to 270Hz, and the magnetic induction intensity generated by the superconducting coil at the center of the chamber is 2 to 5 tesla.

6. A plasma CVD apparatus with a superconducting magnet according to claim 1, wherein the chamber lifting device is disposed on the bottom plate and includes a lifting frame (24) and a lifting base, the lifting frame is provided with a lead screw (25), the top of the lead screw is connected to a lifting motor (26), the lifting base is provided with a lead screw nut (27) adapted to the lead screw, and the lifting base is fixedly connected to the sidewall of the chamber through a connecting rod (28).

7. A plasma CVD apparatus having a superconducting magnet according to claim 6, wherein the elevating base includes a frame (29) and a buffer block (30), a slide rod (31) is vertically provided on the frame, the buffer block is provided in the middle of the slide rod through a slide sleeve (32), buffer springs (33) are sleeved on the slide rods on the upper and lower sides of the slide sleeve, one end of each buffer spring abuts against the slide sleeve, the other end abuts against the frame, the lead screw nut is fixed on the buffer block, and the connecting rod is fixed on the frame.

8. A plasma CVD apparatus with a superconducting magnet according to claim 1, wherein the mode converter has a cross-shaped structure including two waveguide ports and two coaxial ports, the microwave generator is connected to the mode converter through a waveguide three-screw adapter (34), a waveguide short-circuit section (35) is provided on a side of the mode converter opposite to the microwave generator, an outer conductor of a coaxial output end of the mode converter is connected to a microwave input hole on the base plate, an inner conductor (36) of the coaxial output end passes through the microwave input hole to be connected to the substrate stage, a coaxial short-circuit section (37) is provided on a side opposite to the coaxial output end, and an upper edge of the microwave input hole is provided with a tapered surface (38).

9. A plasma CVD apparatus with a superconducting magnet according to claim 8, wherein the inner conductor of the coaxial output end is a hollow structure, a cooling water input pipe (39) is sleeved in the inner conductor, a cooling water output channel (40) is formed between an inner wall of the inner conductor and an outer wall of the cooling water input pipe, a substrate table cooling chamber (41) is provided inside the substrate table, an opening is provided at a bottom of the cooling chamber, the inner conductor of the coaxial output end passes through the microwave input hole to be connected with the opening at the bottom of the cooling chamber, an upper end of the cooling water input pipe is located in the substrate table cooling chamber, and an annular diffusion plate (42) is provided at a top end of the cooling water input pipe.

10. A plasma CVD apparatus with a superconducting magnet according to any of claims 1-9, wherein the chamber wall is a double-layer structure, an annular water cooling chamber (52) is formed between the two chamber walls, and an observation hole (43) and a temperature measuring hole penetrating through the chamber wall are further formed on the chamber wall; the air inlet (44) of the cavity is arranged on the cavity wall at the periphery of the top of the cavity, the air inlet is communicated with an air inlet diffusion groove (45) arranged around the cavity wall, an air inlet joint (46) is connected to the air inlet diffusion groove, an air outlet (47) of the cavity is arranged on the cavity wall at the periphery of the bottom of the cavity, the air outlet is communicated with an air collection groove (48) arranged around the cavity wall, and an air outlet joint (49) is connected to the air collection groove.