MPCVD equipment and method for preparing large-size polycrystalline diamond film

Abstract

The invention relates to the technical field of microwave plasma chemical vapor deposition, in particular to MPCVD equipment and a preparation method for preparing a large-size polycrystalline diamond film, a quartz ring is arranged in a reaction chamber, a water-cooled copper substrate table is arranged at the top of the quartz ring, a molybdenum ring is arranged at the top of the water-cooled copper substrate table, and a water-cooled copper-based sample table is arranged in the center of the molybdenum ring; the bottom of the water-cooled copper-based sample table is connected with a lifting pipe, the top of the water-cooled copper-based sample table is provided with a molybdenum support, and the top of the molybdenum support is provided with a sample ring; two infrared temperature measurement sensors are arranged outside a temperature measurement observation window of the reaction chamber and are respectively aligned with the edge and the central area of the sample ring; a copper-based sample table cooling water path and a thermal resistance wire are arranged in the water-cooled copper-based sample table in a staggered manner, the thermal resistance wire is electrically connected with the electric heating control device, and the electric heating control device is electrically connected with the double-infrared temperature measuring device. According to the method, the temperature uniformity of the inner and outer areas in the large-size polycrystalline diamond film deposition process can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave plasma chemical vapor deposition, and particularly to an MPCVD device and a preparation method for preparing large-size polycrystalline diamond films. Background Art

[0002] The preparation methods of CVD (Chemical Vapor Deposition) polycrystalline diamond films include high-power DC arc plasma jet CVD, hot filament CVD, and MPCVD (Microwave Plasma Chemical Vapor Deposition), etc. The preparation of optical-grade and electronic-grade polycrystalline diamond films requires an ideal deposition rate and an extremely low or controllable defect density. MPCVD without electrode pollution discharge has inevitably become an ideal method for preparing electronic-grade and optical-grade polycrystalline diamond films.

[0003] Compared with the demanding preparation and application of optical-grade and electronic-grade polycrystalline diamond films, polycrystalline diamond films are more widely used, in greater demand, and more urgent as heat sinks for semiconductor power device heat dissipation. They have great application potential for improving the near-junction heat dissipation ability of third-generation semiconductor materials such as silicon carbide and gallium nitride materials under high-power density conditions.

[0004] However, in the existing MPCVD devices for preparing polycrystalline diamond films, when preparing large-size high-quality polycrystalline diamond films of 2 inches and above, affected by the shape and distribution of the plasma above the deposition pedestal, the energy of the plasma shows the characteristics of strong in the middle and weak at the edges, resulting in a decreasing temperature state of the deposited sample from the central region to the edge region during the deposition process. This phenomenon becomes more obvious as the microwave power increases and the device operates for a long time. At the same time, affected by the uneven heat dissipation of the deposition pedestal, the uniformity of the deposited polycrystalline diamond film cannot be guaranteed. There is a certain height difference between the inside and outside of the polycrystalline diamond film, the crystal stress is large, and the deposited crystal warps severely and is easily broken after peeling, seriously affecting the crystal quality, and thus unable to meet the subsequent processing procedures such as cutting, grinding, and polishing, and is extremely prone to the phenomenon of breaking and cracking, thereby affecting the application of polycrystals in the preparation of semiconductor devices. Therefore, the existing MPCVD devices for preparing polycrystalline diamond films are difficult to prepare large-size high-quality polycrystalline diamond films of 2 inches and above. Summary of the Invention

[0005] In order to solve the technical problem that in the existing MPCVD equipment for preparing polycrystalline diamond films, due to the shape and distribution of plasma, there is a certain temperature gradient in the inner and outer regions of the deposition sample, resulting in uneven temperature field distribution, which makes it impossible to prepare large-sized high-quality polycrystalline diamond films of 2 inches and above, the present invention provides, on the one hand, an MPCVD equipment for preparing large-sized polycrystalline diamond films, and on the other hand, provides a method for preparing large-sized polycrystalline diamond films.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the MPCVD equipment for preparing large-size polycrystalline diamond films in the present invention is: The MPCVD equipment for preparing large-size polycrystalline diamond film comprises a reaction chamber, wherein a quartz ring is arranged in the reaction chamber, a water-cooled copper substrate table is arranged at the top center of the quartz ring, a molybdenum ring is arranged at the top center of the water-cooled copper substrate table, a water-cooled copper-based sample table is arranged at the center of the molybdenum ring, the inner diameter of the molybdenum ring is larger than the outer diameter of the water-cooled copper-based sample table, a lifting tube is connected to the bottom center of the water-cooled copper-based sample table, the lifting tube can be lifted and lowered, the lifting tube passes downward through the water-cooled copper-based substrate table and the quartz ring and then passes out of the reaction chamber, a molybdenum holder is coaxially arranged on the top of the water-cooled copper-based sample table, and a sample ring is coaxially arranged on the top of the molybdenum holder; the reaction chamber is provided with a temperature measuring device. An observation window is provided, and two infrared temperature sensors are arranged outside the temperature measurement observation window, and the two infrared temperature sensors are respectively aimed at the edge and the center area of ​​the sample ring; a copper-based sample stage cooling water circuit and a thermal resistance wire are staggered inside the water-cooled copper-based sample stage, and the pipes of the copper-based sample stage cooling water circuit and the wires of the thermal resistance wire extend from the inside of the lifting tube to the reaction chamber, and the pipes of the copper-based sample stage cooling water circuit extend out of the reaction chamber and are connected to the chiller, and the wires of the thermal resistance wire extend out of the reaction chamber and are electrically connected to the electric heating control device, the electric heating control device is electrically connected to the dual infrared temperature measuring device, and the dual infrared temperature measuring device is electrically connected to the two infrared temperature sensors.

[0007] With the above structural scheme, the copper-based sample stage cooling water paths and thermal resistance wires staggered inside the water-cooled copper-based sample stage can effectively adjust the temperature of the substrate sample in the molybdenum tray and the upper sample ring. The copper-based sample stage cooling water paths set inside the water-cooled copper-based sample stage can take away excess heat and prevent the water-cooled copper-based sample stage from overheating. The staggered cooling water paths and thermal resistance wires inside the water-cooled copper-based sample stage, in conjunction with infrared temperature sensors and electric heating control devices, can accurately adjust the temperature of the water-cooled copper-based sample stage according to the temperature feedback of the edge and center areas of the sample ring, thereby reducing the temperature gradient of the deposited sample from the center to the edge during the deposition process, making the temperature field distribution more uniform, and providing a stable temperature environment for the preparation of large-size high-quality polycrystalline diamond films.

[0008] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, when the difference in the temperatures detected by two infrared temperature sensors exceeds the set temperature difference range, the electric heating control device controls the heating of the heating wire.

[0009] With the above structural scheme, the real-time monitoring and automatic adjustment of the temperature of the deposited sample in the sample ring are realized. It can quickly respond to temperature changes, maintain the relative stability of the temperature in the inner and outer regions of the deposited sample in the sample ring, avoid the decline in the deposition quality of polycrystalline diamond films caused by excessive temperature differences, effectively improve the uniformity and stability of film deposition, and ensure the quality of large-size polycrystalline diamond films.

[0010] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, a copper substrate table cooling water path is provided inside the water-cooled copper substrate table. The pipeline of the copper substrate table cooling water path extends out of the reaction chamber from the central hole of the quartz ring, and the pipeline of the copper substrate table cooling water path is connected to a chiller after extending out of the reaction chamber.

[0011] With the above structural scheme, the copper substrate table cooling water path provided inside the water-cooled copper substrate table can take away excess heat, prevent the water-cooled copper substrate table from overheating, and further effectively adjust the temperature of the substrate sample in the molybdenum holder and the upper sample ring through heat conduction.

[0012] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, the thickness of the molybdenum ring is 14 - 18 mm, the outer diameter of the molybdenum ring is the same as the outer diameter of the water-cooled copper substrate table, and the inner diameter of the molybdenum ring is 0.5 - 3 mm larger than the outer diameter of the water-cooled copper-based sample table.

[0013] With the above structural scheme, while ensuring the structural strength of the molybdenum ring, the heat conduction path can be optimized. The appropriate thickness helps to evenly transfer heat and avoid uneven heat conduction caused by the molybdenum ring being too thin or too thick.

[0014] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, the thickness of the molybdenum holder is 1 - 5 mm, and the radial dimensions of the molybdenum holder are the same as those of the water-cooled copper-based sample table.

[0015] With the above structural scheme, the molybdenum holder can be closely attached to the water-cooled copper-based sample table, achieving good synergy in the heat transfer process. The molybdenum holder can transfer the temperature of the water-cooled copper-based sample table to the deposited sample more evenly, and at the same time buffer the stress generated by temperature changes between the water-cooled copper-based sample table and the deposited sample to a certain extent, ensuring the temperature consistency of the deposited sample during the deposition process, which is beneficial to improving the deposition quality and stability of large-size polycrystalline diamond films.

[0016] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, the radial size of the water-cooled copper-based sample stage is 1-5 inches.

[0017] Adopting the above structural scheme enables the equipment to adapt to the preparation of large-size polycrystalline diamond films with different size requirements.

[0018] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, the temperature measurement and observation window is a microwave emission window, the microwave power adjustment range is 0.6KW - 12KW, and the frequencies of the available microwave sources are 2450MHz or 915MHz.

[0019] Adopting the above structural scheme enables the equipment to more flexibly adjust the microwave power and frequency according to different process requirements for preparing polycrystalline diamond films. Different microwave parameters will affect the generation, distribution, and energy of the plasma, and thus affect the deposition rate, quality, and crystal structure of the film. The wide range of microwave power adjustment and multi-frequency selection provide more possibilities for optimizing the preparation process of polycrystalline diamond films and help meet diverse scientific research and production needs.

[0020] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, when the lifting tube is at the zero point of the stroke, the height difference between the water-cooled copper-based sample stage and the water-cooled copper substrate stage below is 1mm.

[0021] Adopting the above structural scheme, the appropriate height difference helps to form reasonable heat conduction and heat exchange conditions between the water-cooled copper-based sample stage and the water-cooled copper substrate stage at the initial stage of equipment startup, avoiding abnormal temperature distribution caused by the two being too close or too far apart, laying a good foundation for the subsequent stable deposition process of polycrystalline diamond films, and being beneficial to improving the repeatability and stability of film deposition.

[0022] As a preferred implementation of the MPCVD equipment for preparing large-size polycrystalline diamond films, there is a lifting motor outside the reaction chamber. The output end of the lifting motor is coaxially connected to a worm. The worm is horizontally arranged. The worm meshes with a worm gear. The worm gear is fixedly installed outside the reaction chamber. A connecting hole is opened in the center of the worm gear. Internal threads are opened on the inner peripheral surface of the connecting hole. External threads are opened on the outer peripheral surface of the lifting tube. One end of the lifting tube extending out of the reaction chamber is threadedly connected to the connecting hole. The top end of the lifting tube is rotatably connected to the bottom of the water-cooled copper-based sample stage.

[0023] With the above structural solution, the worm and worm gear drive has self-locking property, which can ensure that the lifting pipe remains stable after being adjusted to the specified position, and avoid the height change of the water-cooled copper-based sample stage due to accidental factors. Moreover, the worm and worm gear drive has high precision, and can flexibly adjust the height of the water-cooled copper-based sample stage according to the requirements of the deposition process, so as to optimize the interaction between the plasma and the deposited sample, improve the quality and uniformity of the thin film deposition, and at the same time facilitate the operation and maintenance of the equipment.

[0024] The technical solution adopted by the method for preparing large-size polycrystalline diamond thin films in the present invention is as follows: A method for preparing large-size polycrystalline diamond thin films, using the MPCVD equipment for preparing large-size polycrystalline diamond thin films as described above, comprising the following steps: Place the substrate sample in a methanol suspension containing diamond micropowder for ultrasonic treatment. After the treatment, transfer it to alcohol for ultrasonic cleaning. After the cleaning and natural drying, place the substrate sample in a sample ring selected according to the substrate sample specifications; Raise the lifting pipe to lift the water-cooled copper-based sample stage to a position flush with the molybdenum support and the molybdenum ring; Adjust the positions of the two infrared temperature sensors so that the two infrared temperature sensors are respectively aligned with the edge and the central area of the sample ring, so that the two infrared temperature sensors focus on detecting the temperatures of the inner and outer areas of the deposited sample through the temperature measurement observation window; Adjust the chamber pressure, operate the chiller, introduce the polycrystalline growth atmosphere after proportional mixing into the reaction chamber, operate the microwave source, adjust the microwave power, and control the deposition temperature; The dual-infrared temperature measurement device feeds back the temperature parameters of the deposited sample detected by the two infrared temperature sensors to the electric heating control device; when the temperature difference between the inner and outer areas of the sample exceeds the set temperature difference range, the electric heating control device controls the heating wire to heat, and controls the temperature difference between the inner and outer areas of the sample within the set temperature difference range; As the growth process progresses, control the lifting of the lifting pipe to drive the lifting of the water-cooled copper-based sample stage, and adjust the height required for the deposition of the deposited sample.

[0025] The beneficial effects of the present invention include: Provide a large-size polycrystalline diamond growth device with efficient heat conduction, small temperature gradient between the inner and outer areas of the deposited sample, uniform and continuous temperature field distribution, and precise and controllable deposition process. This device can effectively reduce the large thermal stress generated during the deposition of polycrystalline diamond thin films by MPCVD due to the uneven temperature inside and outside the deposited sample, reduce the probability of cracking and breaking of the deposited sample in the subsequent processing steps, effectively improve the uniformity and crystal quality of the deposited polycrystalline diamond thin films, can directly prepare high-precision and high-quality large-size polycrystalline diamond, and can directly meet the application requirements of semiconductor device preparation after preparation. Description of the Drawings

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0027] Figure 1 It is a schematic internal structure diagram of the MPCVD device for preparing large-size polycrystalline diamond films in the specific embodiment of the present invention; Figure 2 It is a schematic structural diagram of the worm gear and the worm in the specific embodiment of the present invention.

[0028] List of components and reference numerals: 1. Reaction chamber; 2. Quartz ring; 3. Water-cooled copper substrate stage; 4. Molybdenum ring; 5. Water-cooled copper-based sample stage; 6. Lifting tube; 7. Molybdenum holder; 8. Sample ring; 9. Infrared temperature sensor; 10. Cooling water path for copper substrate stage; 11. Cooling water path for copper-based sample stage; 12. Heating resistance wire; 13. Chiller; 14. Electric heating control device; 15. Dual infrared temperature measurement device; 16. Lifting motor; 17. Worm; 18. Worm gear; 19. Temperature measurement and observation window. Specific embodiments

[0029] To make the objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in this specific embodiment. Obviously, the embodiments described below are only some embodiments of the present invention, not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0030] Refer to Figure 1, this embodiment proposes an MPCVD device for preparing large-sized polycrystalline diamond films, including a reaction chamber 1. Inside the reaction chamber 1, there is a quartz ring 2. At the top center of the quartz ring 2, there is a water-cooled copper substrate stage 3. At the top center of the water-cooled copper substrate stage 3, there is a molybdenum ring 4. In the center of the molybdenum ring 4, there is a water-cooled copper-based sample stage 5. The radial size of the water-cooled copper-based sample stage 5 is 1 - 5 inches, and the thickness is 7 mm. The inner diameter of the molybdenum ring 4 is larger than the outer diameter of the water-cooled copper-based sample stage 5. The thickness of the molybdenum ring 4 is 14 - 18 mm. The outer diameter of the molybdenum ring 4 is the same as the outer diameter of the water-cooled copper substrate stage 3. The inner diameter of the molybdenum ring 4 is 0.5 - 3 mm larger than the outer diameter of the water-cooled copper-based sample stage 5. At the bottom center of the water-cooled copper-based sample stage 5, there is a lifting tube 6 which can be lifted and lowered. The lifting tube 6 passes downward through the water-cooled copper substrate stage 3 and the quartz ring 2 and then passes out of the reaction chamber 1. Coaxially arranged on the top of the water-cooled copper-based sample stage 5 is a molybdenum holder 7. Coaxially arranged on the top of the molybdenum holder 7 is a sample ring 8. The molybdenum ring 4, the molybdenum holder 7, and the sample ring 8 are all made of molybdenum. The surface roughness is Ra0.2. The molybdenum material has characteristics such as a high melting point, good thermal stability, and chemical stability. It is not easy to deform and undergo chemical reactions in the high-temperature MPCVD deposition environment. At the same time, the low surface roughness can provide a relatively flat and smooth substrate for the growth of polycrystalline diamond films, which is conducive to the uniform nucleation and growth of diamond crystals, reduces crystal defects, thereby improving the quality and crystallization performance of polycrystalline diamond films, and helps to prepare high-quality large-sized polycrystalline diamond films. The thickness of the molybdenum holder 7 is 1 - 5 mm, and the radial size of the molybdenum holder 7 is the same as that of the water-cooled copper-based sample stage 5. The size of the sample ring 8 is designed in multiple specifications, and different sample rings 8 can be replaced according to the radial size and deposition thickness of the sample to be deposited.

[0031] The reaction chamber 1 is provided with a temperature-measuring observation window 19. Outside the temperature-measuring observation window 19, there are two infrared temperature sensors 9. The two infrared temperature sensors 9 are respectively aligned with the edge and the central area of the sample ring 8. The temperature measurement range of the infrared temperature sensors 9 is 300 - 1400 °C. The temperature-measuring observation window 19 is a microwave emission window. The microwave power adjustment range is 0.6 KW - 12 KW, and the frequency of the available microwave source is 2450 MHz or 915 MHz.

[0032] Inside the water-cooled copper substrate stage 3, there is a copper substrate stage cooling water channel 10. Inside the water-cooled copper-based sample stage 5, there are staggered copper-based sample stage cooling water channels 11 and heating resistance wires 12. The pipeline of the copper substrate stage cooling water channel 10 extends out of the reaction chamber 1 from the central hole of the quartz ring 2. The pipelines of the copper-based sample stage cooling water channels 11 and the wires of the heating resistance wires 12 extend out of the reaction chamber 1 from inside the lifting tube 6. After the pipelines of the copper substrate stage cooling water channel 10 and the copper-based sample stage cooling water channels 11 extend out of the reaction chamber 1, they are connected to the chiller 13. After the wires of the heating resistance wires 12 extend out of the reaction chamber 1, they are electrically connected to the electric heating control device 14. The electric heating control device 14 is electrically connected to the dual infrared temperature measurement device 15. The dual infrared temperature measurement device 15 is electrically connected to two infrared temperature sensors 9. When the difference between the temperatures detected by the two infrared temperature sensors 9 exceeds the set temperature difference range, the electric heating control device 14 controls the heating resistance wire 12 to heat. The heating temperature range of the heating resistance wire 12 is 50 - 300 °C, and the heating temperature is regulated by the electric heating control device 14.

[0033] The temperature of the cooling water in the copper substrate stage cooling water channel 10 and the copper-based sample stage cooling water channels 11 is 10 - 35 °C, the regulation accuracy is 0.1 °C, the cooling water flow rate is greater than or equal to 50 L / min, and the flow rate can be regulated by the chiller 13.

[0034] When the lifting tube 6 is at the zero point of the stroke, the height difference between the water-cooled copper-based sample stage 5 and the lower water-cooled copper substrate stage 3 is 1 mm.

[0035] Refer to Figure 1 and 2 , in order to realize the lifting of the lifting tube 6, in this embodiment, there is a lifting motor 16 outside the reaction chamber 1. The output end of the lifting motor 16 is coaxially connected to the worm 17. The worm 17 is horizontally arranged. The worm 17 meshes with the worm gear 18. The worm gear 18 is fixedly installed outside the reaction chamber 1. A connection hole is opened in the center of the worm gear 18. Internal threads are opened on the inner peripheral surface of the connection hole. External threads are opened on the outer peripheral surface of the lifting tube 6. One end of the lifting tube 6 extending out of the reaction chamber 1 is threadedly connected to the connection hole. The top end of the lifting tube 6 is rotatably connected to the bottom of the water-cooled copper-based sample stage 5.

[0036] This embodiment can effectively improve the quality of polycrystalline deposition. Through the lifting control of the water-cooled copper-based sample stage 5, combined with the dual-infrared temperature measurement device 15 linked to the electric heating control device 14 to control the heating of the internal heating resistance wire 12 of the water-cooled copper-based sample stage 5, the temperature gradient inside and outside the deposited sample during the deposition process is reduced, so that the temperature field distribution is uniform, and each deposition parameter of the polycrystalline substrate is accurately controlled within the process requirements, avoiding problems such as the collapse of the substrate sample and the deposited sample, low polycrystalline quality, and low processing yield due to uneven heat transfer distribution and thermal stress during the deposition process. The sample ring 8 can reduce the plasma edge effect and avoid the poor crystal quality at the edge of the substrate sample caused by the plasma adsorbing the edge of the substrate sample, which provides a good guarantee for the crystal quality. The MPCVD equipment for preparing large-size polycrystalline diamond films in this embodiment can achieve the deposition and preparation of high-precision large-size polycrystalline diamond with a size of 1 to 4 inches.

[0037] The structure of the MPCVD equipment for preparing large-size polycrystalline diamond films in this embodiment is relatively simple, which can effectively meet the needs of industrial production and provide a high-quality and reliable solution for industrial production and laboratory growth research.

[0038] This embodiment also proposes a method for preparing large-size polycrystalline diamond films. Using the above-mentioned MPCVD equipment for preparing large-size polycrystalline diamond films, taking a 3-mm-thick two-inch silicon substrate sample as an example, the method for preparing large-size polycrystalline diamond films includes the following steps: Place the silicon substrate sample in a methanol suspension containing diamond micropowder with 1000 - 6000 meshes and ultrasonically treat it for 30 minutes. After the treatment, transfer it to alcohol and ultrasonically clean it for 20 minutes. After the cleaning and natural drying, place the substrate sample in the sample ring 8 placed on the molybdenum holder 7 according to the substrate sample specifications. Operate the lifting motor 16 to raise the lifting tube 6, thereby lifting the water-cooled copper-based sample stage 5 to a position flush with the molybdenum holder 7 and the molybdenum ring 4. Adjust the positions of the two infrared temperature sensors 9 so that the two infrared temperature sensors 9 are respectively aligned with the edge and the central area of the sample ring 8, so as to detect the temperatures of the inner and outer areas of the deposited sample. Adjust the chamber pressure to 10 - 300 Torr, operate the chiller 13 to set the cooling circulating water temperature to 10 - 35 °C, introduce a polycrystalline growth atmosphere containing hydrogen, nitrogen, methane, and oxygen after mixing in proportion, operate the microwave source, adjust the microwave power to 0.5 KW - 12 KW, and control the deposition temperature to 600 - 1000 °C. The dual-infrared temperature measurement device 15 feeds back the temperature parameters of the deposited sample detected by the two infrared temperature sensors 9 to the electric heating control device 14; when the temperature difference between the inner and outer regions of the deposited sample exceeds 10 - 100 °C, the electric heating program is started to control the heating of the heating wire 12, and the temperature difference between the inside and outside of the deposited sample is controlled within 10 - 100 °C; As the growth process progresses, the height of the growth sample continuously increases. The lifting motor 16 is operated to control the lifting of the lifting tube 6 to drive the water-cooled copper-based sample stage 5 and the molybdenum holder 7 to move, adjusting the suitable height required for the deposition of the deposited sample, so that the deposited sample is always in the best position.

[0039] In this embodiment, the growth rate of the deposited sample is 0.1 - 100 μm / h, the lifting rate of the lifting motor 16 is 0.1 - 1000 μm / h, the regulation range of the height of the water-cooled copper-based sample stage 5 is 0 - 5000 μm, and the regulation accuracy is 0.1 μm.

[0040] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The MPCVD equipment for preparing large-size polycrystalline diamond films includes a reaction chamber (1), and is characterized in that a quartz ring (2) is arranged inside the reaction chamber (1). At the center of the top of the quartz ring (2), there is a water-cooled copper substrate table (3). At the center of the top of the water-cooled copper substrate table (3), there is a molybdenum ring (4). Inside the center of the molybdenum ring (4), there is a water-cooled copper-based sample table (5). The inner diameter of the molybdenum ring (4) is larger than the outer diameter of the water-cooled copper-based sample table (5). At the center of the bottom of the water-cooled copper-based sample table (5), there is a lifting tube (6) which can be lifted. The lifting tube (6) extends downward through the water-cooled copper substrate table (3) and the quartz ring (2) and then passes through the reaction chamber (1). At the top of the water-cooled copper-based sample table (5) coaxially, there is a molybdenum holder (7). At the top of the molybdenum holder (7) coaxially, there is a sample ring (8); the reaction chamber (1) is provided with a temperature-measuring observation window (19). Outside the temperature-measuring observation window (19), there are two infrared temperature sensors (9), and the two infrared temperature sensors (9) are respectively aligned with the edge and the central area of the sample ring (8); inside the water-cooled copper-based sample table (5), there are criss-crossed copper-based sample table cooling water channels (11) and heating resistance wires (12). The pipelines of the copper-based sample table cooling water channels (11) and the wires of the heating resistance wires (12) extend out of the reaction chamber (1) from inside the lifting tube (6). After the pipelines of the copper-based sample table cooling water channels (11) extend out of the reaction chamber (1), they are connected to a chiller (13). After the wires of the heating resistance wires (12) extend out of the reaction chamber (1), they are electrically connected to an electric heating control device (14). The electric heating control device (14) is electrically connected to a dual-infrared temperature measuring device (15). The dual-infrared temperature measuring device (15) is electrically connected to the two infrared temperature sensors (9).

2. The MPCVD apparatus for preparing large-sized polycrystalline diamond films according to claim 1, wherein, When the difference between the temperatures detected by the two infrared temperature sensors (9) exceeds the set temperature difference range, the electric heating control device (14) controls the heating resistance wire (12) to heat.

3. The MPCVD apparatus for preparing large-size polycrystalline diamond films according to claim 1, wherein, inside the water-cooled copper substrate table (3), there is a copper substrate table cooling water channel (10). The pipeline of the copper substrate table cooling water channel (10) extends out of the reaction chamber (1) from the central hole of the quartz ring (2). After the pipeline of the copper substrate table cooling water channel (10) extends out of the reaction chamber (1), it is connected to the chiller (13).

4. The MPCVD apparatus for preparing large-sized polycrystalline diamond films according to claim 1, characterized in that, the thickness of the molybdenum ring (4) is 14 - 18 mm. The outer diameter of the molybdenum ring (4) is the same as the outer diameter of the water-cooled copper substrate table (3). The inner diameter of the molybdenum ring (4) is 0.5 - 3 mm larger than the outer diameter of the water-cooled copper-based sample table (5).

5. The MPCVD apparatus for preparing large-size polycrystalline diamond films according to claim 1, wherein, the thickness of the molybdenum holder (7) is 1 - 5 mm. The radial dimensions of the molybdenum holder (7) and the water-cooled copper-based sample table (5) are the same.

6. The MPCVD apparatus for preparing large-sized polycrystalline diamond films according to claim 5, characterized in that, the radial dimension of the water-cooled copper-based sample table (5) is 1 - 5 inches.

7. The MPCVD apparatus for preparing large-sized polycrystalline diamond films according to claim 1, characterized in that, the temperature-measuring observation window (19) is a microwave emission window. The microwave power regulation range is 0.6 KW - 12 KW. The frequency of the available microwave source is 2450 MHz or 915 MHz.

8. The MPCVD apparatus for preparing large-size polycrystalline diamond films according to claim 1, wherein, When the lifting tube (6) is at the zero point of the stroke, the height difference between the water-cooled copper-based sample table (5) and the water-cooled copper substrate table (3) below is 1 mm.

9. The MPCVD apparatus for preparing large-sized polycrystalline diamond films according to claim 1, wherein, An elevating motor (16) is provided outside the reaction chamber (1). The output end of the elevating motor (16) is coaxially connected to a worm (17). The worm (17) is horizontally arranged and meshes with a worm gear (18). The worm gear (18) is fixedly installed outside the reaction chamber (1). A connection hole is opened in the center of the worm gear (18), and an internal thread is opened on the inner peripheral surface of the connection hole. An external thread is opened on the outer peripheral surface of the elevating pipe (6). One end of the elevating pipe (6) extending out of the reaction chamber (1) is threadedly connected to the connection hole. The top end of the elevating pipe (6) is rotatably connected to the bottom of the water-cooled copper-based sample stage (5).

10. A method for preparing a large-size polycrystalline diamond film, characterized in that, Using the MPCVD equipment for preparing large-size polycrystalline diamond films according to any one of claims 1-9, the following steps are included: Place the substrate sample in a methanol suspension containing diamond micropowder for ultrasonic treatment. After the treatment, transfer it to alcohol for ultrasonic cleaning. After the cleaning and natural drying, place the substrate sample in a sample ring (8) selected according to the substrate sample specifications; Raise the elevating pipe (6) to lift the water-cooled copper-based sample stage (5) to a position flush with the molybdenum holder (7) and the molybdenum ring (4); Adjust the positions of the two infrared temperature sensors (9) so that the two infrared temperature sensors (9) respectively align with the edge and the central area of the sample ring (8), so that the two infrared temperature sensors (9) focus on detecting the temperatures of the inner and outer areas of the deposited sample through the temperature measurement observation window (19); Adjust the chamber pressure, operate the chiller (13), introduce the polycrystalline growth atmosphere after proportional mixing into the reaction chamber (1), operate the microwave source, adjust the microwave power, and control the deposition temperature; The dual-infrared temperature measurement device (15) feeds back the temperature parameters of the deposited sample detected by the two infrared temperature sensors (9) to the electric heating control device (14); when the temperature difference between the inner and outer areas of the deposited sample exceeds the set temperature difference range, the electric heating control device (14) controls the heating of the heating wire (12) to control the temperature difference between the inner and outer areas of the deposited sample within the set temperature difference range; As the growth process progresses, control the lifting of the elevating pipe (6) to drive the lifting of the water-cooled copper-based sample stage (5) to adjust the height required for the deposition of the deposited sample.

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