A microwave reaction apparatus

Abstract

The utility model provides a microwave reaction device, including: microwave resonance cavity, growth base, mode conversion waveguide, microwave antenna, its characterized in be: microwave antenna is located in mode conversion waveguide, mode conversion waveguide has the perforation for microwave antenna to pass, the periphery of microwave antenna and the hole wall between the perforation leaves the preset interval, microwave antenna passes through the rotating mechanism and mode conversion waveguide rotation cooperation, by the above-mentioned preset interval, in the rotating mechanism drive microwave antenna around the rotation center of rotating mechanism rotation makes the central axis of microwave antenna relative to the central line of growth base inclination's state, further change: the plasma ball of generation can always be located in the just above of growth base and covers diamond seed crystal completely, ensures diamond seed crystal in the whole growth process receives the even heat distribution.

Description

Technical Field

[0001] This utility model relates to the field of plasma chemical vapor deposition technology, and in particular to a microwave reaction device. Background Technology

[0002] Microwave plasma chemical vapor deposition (MPCVD) is a leading technology for preparing diamond materials. Chinese invention patent application ZL202310904924.3 (publication number CN116939939A) discloses a microwave plasma device. This device includes a microwave cavity comprising a resonant cavity and a vacuum cavity. The two ends of the resonant cavity are connected to a microwave mode converter and the vacuum cavity, respectively. A microwave antenna extending into the resonant cavity is mounted on the microwave mode converter. A quartz window is provided between the resonant cavity and the vacuum cavity to isolate them. The microwave mode converter, resonant cavity, and vacuum cavity are sequentially distributed along the axial direction H of the vacuum cavity. A microwave power source emitted from a microwave generator is coupled to the microwave mode converter. The TEM wave in the coaxial line is coupled into the resonant cavity of the cylindrical cavity through the microwave antenna to form a TM01 mode in the circular waveguide. This mode is then coupled to the vacuum cavity through the quartz window to generate plasma.

[0003] Due to deviations in processing and assembly, the position and shape of the plasma sphere often deviate from the expected shape. In diamond growth, temperature control is crucial for obtaining high-quality diamonds. If the plasma sphere shifts, the diamond seed crystal will suffer uneven heating during growth. To ensure uniform heat distribution throughout the growth process, the plasma sphere needs to be adjusted to completely cover the growth stage. However, existing microwave reactors can only regulate the temperature during diamond growth by raising and lowering the growth stage, as disclosed in Chinese invention patent application CN202310916192.X (publication number CN116926666A), entitled "A Microwave Reactor for Easily Adjusting Growth Temperature." However, this device, relying solely on raising and lowering the growth stage, cannot ensure that the diamond seed crystal is always completely covered by the plasma sphere during growth. If the plasma sphere shifts and fails to completely cover the growth stage, the diamond seed crystal will still suffer uneven heating, leading to growth defects such as uneven texture, cracks, and conical irregularities.

[0004] Therefore, existing microwave reaction devices need to be improved to ensure that the diamond seed crystal receives uniform heat distribution throughout the growth process. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a microwave reaction device in which a plasma sphere can completely cover the diamond seed crystal on the growth substrate, in view of the above-mentioned existing technology.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: the microwave reaction device includes:

[0007] Microwave resonant cavity;

[0008] A growth platform is provided inside the microwave resonant cavity and is used to place the diamond seed crystal to be grown.

[0009] A mode-conversion waveguide, located on the top wall of the microwave resonant cavity, is used to convert the microwave energy emitted by the microwave generator into a mode-conversion waveguide. 10 TE mode conversion to meet the requirements of plasma sphere excitation in microwave resonant cavities 01 mold;

[0010] A microwave antenna is assembled in the mode conversion waveguide. The end of the microwave antenna extends into the microwave resonant cavity and faces the growth substrate. It is used to radiate the microwave energy converted by the mode conversion waveguide into the microwave resonant cavity. After the strong electric field formed by the end of the microwave antenna ionizes the reactive gas, a plasma ball is generated above the growth substrate.

[0011] The feature is that the microwave antenna is inserted into the mode conversion waveguide, the mode conversion waveguide has a through hole for the microwave antenna to pass through, and a preset gap is left between the periphery of the microwave antenna and the wall of the through hole. The microwave antenna is rotated and cooperates with the mode conversion waveguide through a rotating mechanism. With the help of the preset gap, when the rotating mechanism drives the microwave antenna to rotate around the rotation center of the rotating mechanism, so that the central axis of the microwave antenna is tilted relative to the center line of the growth substrate, the generated plasma ball can always be located directly above the growth substrate.

[0012] To facilitate the tilting of the microwave antenna's central axis relative to the centerline of the growth substrate, preferably, the microwave antenna has an adjustment section exposed outside the microwave resonant cavity. This adjustment section can be manually operated or automatically controlled by a control unit. Adjusting the adjustment section allows the microwave antenna to rotate around the rotation center of the rotation mechanism. Taking a manually operated adjustment section as an example, manually swinging the adjustment section allows the microwave antenna to rotate around the rotation center of the rotation mechanism, thereby tilting the central axis of the microwave antenna relative to the centerline of the growth substrate. Of course, the adjustment section can also be automatically operated, such as by installing a drive source outside the adjustment section to drive its swinging motion.

[0013] To enable the microwave antenna and mode conversion waveguide to rotate in coordination, preferably, the rotating mechanism includes a spherical shaft and a spherical shaft receiving cavity disposed in the mode conversion waveguide. The spherical shaft and the spherical shaft receiving cavity are rotatably engaged. The microwave antenna passes through the spherical shaft and is fixedly connected to it. The adjustment part and the end of the microwave antenna are located at opposite ends of the spherical shaft. Through the rotational engagement of the spherical shaft and the spherical shaft receiving cavity, when the adjustment part is swung, the spherical shaft can rotate within the spherical shaft receiving cavity because it is fixedly connected to the microwave antenna. Simultaneously, the microwave antenna can rotate around the spherical shaft as it swung. Furthermore, since the end of the adjustment part and the end of the microwave antenna are located at opposite ends of the spherical shaft, when the adjustment part is swung, the direction of movement of the end of the microwave antenna is centrally symmetrical with respect to the spherical shaft. That is, the end of the microwave antenna moves in the opposite direction to the swung direction of the adjustment part, and the generated plasma sphere also moves in the opposite direction to the swung direction of the adjustment part.

[0014] Furthermore, the distance S that the plasma sphere moves towards the end of the microwave antenna in an inclined direction satisfies the following relationship with the angle θ between the central axis of the microwave antenna after it is tilted and the center line of the growth platform: S = L1 × tanθ, where L1 is the distance between the rotation center of the sphere axis and the growth platform.

[0015] Furthermore, the angle θ between the tilted central axis of the microwave antenna and the centerline of the growth substrate satisfies: 0 ≤ θ ≤ 180 × d × [0.5(L2 + L3 + |L2 - L3|)π] -1 Where d is the width of the preset gap, L2 is the distance from the rotation center of the ball axis to the bottom of the mode conversion waveguide, and L3 is the distance from the rotation center of the ball axis to the top of the microwave resonant cavity. Since the microwave antenna rotates within the aforementioned preset gap, it will be interfered with by the hole wall when it reaches the contact hole wall and will be unable to continue rotating. The maximum rotation angle is related to the width of the preset gap and the distance from the ball axis to the upper or lower end of the hole. If the distance L2 from the rotation center of the ball axis to the bottom of the mode conversion waveguide is large, the microwave antenna will interfere with the emission from the bottom of the mode conversion waveguide when it rotates, and the included angle is related to L2. If the distance L3 from the rotation center of the ball axis to the top of the microwave resonant cavity is large, the microwave antenna will interfere with the emission from the top of the microwave resonant cavity when it rotates, and the included angle is related to L3. Therefore, to reduce the judgment process, 0.5(L2+L3+|L2-L3|) is taken as the distance of the emission interference when the microwave antenna rotates, that is, the larger value of L3 and L2 is taken. Therefore, the maximum included angle θ satisfies 180×d×[0.5(L2+L3+|L2-L3|)π]. -1 .

[0016] To prevent overheating and deformation of the mode-switching waveguide during microwave reaction device operation, preferably, a cooling element is also provided on the mode-switching waveguide to prevent overheating, deformation, or oxidation. Cooling the mode-switching waveguide through the cooling element ensures that the device operates stably within a suitable temperature range.

[0017] Furthermore, the cooling component is a water-cooled plate pressed onto a rectangular waveguide by a pressure block, and the aforementioned L3 is the distance from the rotation center of the ball axis to the pressure block.

[0018] Compared with the prior art, the advantages of this utility model are as follows: the microwave antenna of the microwave reaction device is inserted into the perforation of the mode conversion waveguide, and there is a preset gap between the periphery of the microwave antenna and the wall of the perforation. When the plasma ball is deflected, with the help of this gap, the microwave antenna can be rotated by the rotating mechanism so that the central axis of the microwave antenna is tilted relative to the center line of the growth base. The plasma ball generated by the strong electric field formed at the end of the microwave antenna ionizes the reactive gas and moves towards the tilting direction of the end of the microwave antenna, so that the plasma ball returns to the top of the growth base and completely covers the diamond seed crystal, ensuring that the diamond seed crystal receives uniform heat distribution throughout the growth process. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the microwave reaction device in an embodiment of this utility model;

[0020] Figure 2 for Figure 1 Sectional view at point BB;

[0021] Figure 3 for Figure 2 Enlarged view of point C in the middle;

[0022] Figure 4 This is an exploded view of the ball axis and microwave antenna in an embodiment of this utility model;

[0023] Figure 5 This is a schematic diagram showing the state in which the central axis of the microwave antenna is tilted relative to the center line of the growth substrate in an embodiment of this utility model. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1-5 The figure shown is a preferred embodiment of the present invention.

[0026] The microwave reaction apparatus of this embodiment is used to prepare diamond materials, and includes a microwave resonant cavity 1, a growth stage 2, a mode conversion waveguide 3, and a microwave antenna 4. The growth stage 2 is disposed within the microwave resonant cavity 1 and is used to place the diamond seed crystal to be grown. The mode conversion waveguide 3 is disposed on the top wall of the microwave resonant cavity 1 and is used to convert the microwave energy emitted by the microwave generator into microwave energy via a microwave antenna 4. 10 The mode is converted to the TE required for the excitation of plasma sphere A to adapt to the microwave resonant cavity 1. 01 The microwave antenna 4 is assembled in the mode conversion waveguide 3, and its end 41 extends into the microwave resonant cavity 1 and faces the growth base 2. The microwave antenna 4 is used to radiate the microwave energy converted by the mode conversion waveguide 3 into the microwave resonant cavity 1. After the strong electric field formed by the end 41 of the microwave antenna 4 ionizes the reactive gas, a plasma ball A is generated above the growth base 2.

[0027] However, during diamond growth, the plasma sphere A may shift due to changes in gas pressure and temperature, resulting in it not completely covering the growth substrate 2. If the plasma sphere A shifts, the diamond seed crystal will suffer uneven heating, leading to a series of growth defects, such as uneven texture, cracks, and conical bumps. Therefore, this embodiment creatively designs the microwave antenna 4 to rotate in conjunction with the mode conversion waveguide 3. When the plasma sphere A shifts, the microwave antenna 4 can rotate relative to the mode conversion waveguide 3, so that the central axis 4a of the microwave antenna 4 is tilted relative to the center line 2a of the growth substrate 2. This adjusts the position of the plasma sphere generated by the strong electric field ionizing the reactive gas formed by the end 41 of the microwave antenna 4, ensuring that it is always directly above the growth substrate 2 and completely covers the diamond seed crystal. Of course, the tilt of microwave antenna 4 is only one factor affecting the position of plasma ball A. There are other factors that have a comprehensive impact on the position of plasma ball A, such as cavity shape, temperature, and air pressure. The scheme of adjusting microwave antenna 4 is only one of the schemes for adjusting the position of plasma ball A. This embodiment only describes the scheme of adjusting the position of plasma ball A by tilting microwave antenna 4.

[0028] The specific adjustment scheme for microwave antenna 4 will be described below.

[0029] See Figure 2-4The mode conversion waveguide 3 has a through-hole 31 through which the microwave antenna 4 passes. The microwave antenna 4 passes through the through-hole 31 and is installed in the mode conversion waveguide 3. A preset gap 5 is left between the periphery of the microwave antenna 4 and the hole wall of the through-hole 31. The microwave antenna 4 is rotated and engaged with the mode conversion waveguide 3 through the rotation mechanism 6. With the help of the preset gap 5, the microwave antenna 4 is rotated around the rotation center of the rotation mechanism 6, so that the central axis 4a of the microwave antenna 4 is tilted relative to the center line 2a of the growth base 2. This changes the situation so that the generated plasma sphere A can always be located directly above the growth base 2.

[0030] Specifically, the microwave antenna 4 has an adjustment portion 42 exposed outside the microwave resonant cavity 1. In this embodiment, the adjustment portion 42 is a manual structure. Manually swinging the adjustment portion 42 can cause the microwave antenna 4 to rotate around the rotation center of the rotation mechanism 6, thereby tilting the central axis 4a of the microwave antenna 4 relative to the center line 2a of the growth substrate 2. Of course, the adjustment portion 42 can also be an automatic structure controlled by the control unit, such as by setting a drive source outside the adjustment portion 42 to drive the adjustment portion 42 to swing.

[0031] The rotating mechanism 6 includes a ball shaft 61 and a ball shaft receiving cavity 62 disposed in the mode conversion waveguide 3. The microwave antenna 4 passes through the ball shaft 61 and is fixedly connected to the ball shaft 61. The ball shaft 61 and the ball shaft receiving cavity 62 rotate in cooperation, thereby forcing the ball shaft 61 to rotate within the ball shaft receiving cavity 62 when the adjustment part 42 is swung, and at the same time, the microwave antenna 4 also rotates around the ball shaft 61. In this embodiment, the adjustment part 42 and the end 41 of the microwave antenna 4 are respectively located at both ends of the ball shaft 61. When the adjustment part 42 is swung, the direction of movement of the end 41 of the microwave antenna 4 is centrally symmetrical with respect to the ball shaft 61 with respect to the adjustment part 42, that is, the end 41 of the microwave antenna 4 moves in the opposite direction to the swing direction of the adjustment part 42, and the generated plasma sphere A also moves in the opposite direction to the swing direction of the adjustment part 42. The distance S that the plasma sphere A moves and the angle θ between the central axis 4a of the tilted microwave antenna 4 and the center line 2a of the growth platform 2 satisfy the following: S = L1 × tanθ, where L1 is the distance between the rotation center of the sphere axis 61 and the growth platform 2.

[0032] Since the microwave antenna 4 can only move within the preset gap 5 between its periphery and the wall of the perforation 31, it will be interfered with by the wall when it rotates to contact the wall of the perforation 31 and will be unable to continue rotating. The maximum rotation angle is related to the width of the preset gap 5 and the distance from the ball axis 61 to the upper or lower end of the perforation 31. If the distance L2 from the rotation center of the ball axis 61 to the bottom of the mode conversion waveguide 3 is large, the microwave antenna 4 will interfere with the emission from the bottom of the mode conversion waveguide 3 when it rotates. The included angle is related to L2. If the rotation center of the ball axis 61 is large... Since the distance L3 to the top of the microwave resonant cavity 1 is relatively large, the microwave antenna 4 will interfere with the emission from the top of the microwave resonant cavity 1 when it rotates. Therefore, the angle between the antenna and the top is related to L3. To simplify the judgment process, we take 0.5(L2+L3+|L2-L3|) as the distance of the interference when the microwave antenna 4 rotates, that is, we take the larger value between L3 and L2. Therefore, the angle θ between the central axis 4a of the tilted microwave antenna 4 and the centerline 2a of the growth base 2 satisfies: 0≤θ≤180×d×[0.5(L2+L3+|L2-L3|)π] -1 In this embodiment, the adjustment range of the included angle θ is 0-1.3 degrees, and the adjustment range of the distance S moved by the plasma ball A is 0-11.8 mm.

[0033] Furthermore, to prevent overheating, deformation, or oxidation of the mode conversion waveguide 3 during use of the microwave reaction device, a cooling element 7 is provided on the mode conversion waveguide 3 to ensure that the mode conversion waveguide 3 remains stable within a suitable temperature range during device operation. In this embodiment, the cooling element 7 is a water-cooled plate, which is pressed onto the rectangular waveguide by a pressure block 8. The aforementioned L3 is the distance from the rotation center of the ball shaft 61 to the pressure block 8.

[0034] In summary, the adjustment method of this microwave reaction device is as follows: when the plasma sphere A shifts, the adjustment part 42 is swung in the direction of the shift of the plasma sphere A, and the end 41 of the microwave antenna 4 tilts in the opposite direction, so that the plasma sphere A returns to directly above the growth base 2. For details, see [link to documentation]. Figure 5 When the plasma ball A shifts to the left, the adjustment part 42 of the microwave antenna 4 swings to the left, and the end 41 of the microwave antenna 4 tilts to the right, causing the plasma to move to the right and directly above the growth base 2.

Claims

1. A microwave reaction device, comprising: Microwave resonant cavity (1); A growth platform (2) is located inside the microwave resonant cavity (1) and is used to place the diamond seed crystal to be grown. A mode-conversion waveguide (3) is disposed on the top wall of the microwave resonant cavity (1) and is used to convert the microwave energy emitted by the microwave generator into a mode-conversion waveguide (3). 10 The mode conversion is adapted to the excitation requirements of the plasma sphere (A) of the microwave resonant cavity (1). 01 mold; A microwave antenna (4) is assembled in the mode conversion waveguide (3). The end (41) of the microwave antenna (4) extends into the microwave resonant cavity (1) and faces the growth stage (2). It is used to radiate the microwave energy converted by the mode conversion waveguide (3) into the microwave resonant cavity (1). After the strong electric field formed by the end (41) of the microwave antenna (4) ionizes the reactive gas, a plasma ball (A) is generated above the growth stage (2). Its features are: The microwave antenna (4) is inserted into the mode conversion waveguide (3). The mode conversion waveguide (3) has a through hole (31) through which the microwave antenna (4) passes. A preset gap (5) is left between the periphery of the microwave antenna (4) and the hole wall of the through hole (31). The microwave antenna (4) is rotated and cooperates with the mode conversion waveguide (3) through the rotation mechanism (6). With the help of the preset gap (5), the microwave antenna (4) is rotated around the rotation center of the rotation mechanism (6) so that the central axis (4a) of the microwave antenna (4) is tilted relative to the center line (2a) of the growth base (2). This changes the situation so that the generated plasma ball (A) can always be located directly above the growth base (2).

2. The microwave reaction apparatus according to claim 1, characterized in that: The microwave antenna (4) has an adjustment part (42) exposed outside the microwave resonant cavity (1). The adjustment part (42) is a manual structure or an automatic structure controlled by the control unit. Adjusting the adjustment part (42) can make the microwave antenna (4) rotate around the rotation center of the rotation mechanism (6).

3. The microwave reaction apparatus according to claim 2, characterized in that: The rotating mechanism (6) includes a ball shaft (61) and a ball shaft receiving cavity (62) disposed in the mode conversion waveguide (3). The ball shaft (61) and the ball shaft receiving cavity (62) are rotatably engaged. The microwave antenna (4) passes through the ball shaft (61) and is fixedly connected to the ball shaft (61). The adjustment part (42) and the end (41) of the microwave antenna (4) are respectively located at both ends of the ball shaft (61).

4. The microwave reaction apparatus according to claim 3, characterized in that: The distance S that the plasma sphere (A) moves toward the end (41) of the microwave antenna (4) in an inclined direction satisfies the following relationship with the angle θ between the central axis (4a) of the microwave antenna (4) after it is tilted and the center line (2a) of the growth platform (2): S = L1 × tanθ, where L1 is the distance between the rotation center of the sphere axis (61) and the growth platform (2).

5. The microwave reaction apparatus according to claim 4, characterized in that: The angle θ between the tilted central axis (4a) of the microwave antenna (4) and the centerline (2a) of the growth substrate (2) satisfies: 0≤θ≤180×d×[0.5(L2+L3+|L2-L3|)π] -1 , where d is the width of the preset gap (5), L2 is the distance from the rotation center of the ball shaft (61) to the bottom of the mode conversion waveguide (3), and L3 is the distance from the rotation center of the ball shaft (61) to the top of the microwave resonant cavity (1).

6. The microwave reaction apparatus according to claim 5, characterized in that: A cooling element (7) is also provided on the mode conversion waveguide (3) to prevent overheating, deformation or oxidation of the mode conversion waveguide (3).

7. The microwave reaction apparatus according to claim 6, characterized in that: The cooling component (7) is a water-cooled plate pressed onto a rectangular waveguide by a pressure block (8), and the aforementioned L3 is the distance from the rotation center of the ball shaft (61) to the pressure block (8).

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