A microwave plasma chemical vapor deposition device

Abstract

The invention discloses a microwave plasma chemical vapor deposition device, which belongs to the technical field of chemical vapor deposition devices. The device comprises a microwave generator and three pins connected to the microwave generator, wherein an outlet of the three pins is connected to a mode converter, and the other two outlets of the mode converter are respectively connected to a cavity and a short-circuit piston, a growth platform is arranged in the cavity, an upper cover is arranged above the cavity, and a special gas channel is installed on the upper cover; by connecting multiple groups of coaxial linear microwave antennas to the output port of the converter, the number of quartz channels can be expanded, thereby expanding a high field strength domain and a plasma domain. This method can quickly customize equipment of a required size according to customer requirements to meet different market needs. In actual use, the special gas channel has multiple output ends, thereby corresponding to each group of quartz channels.

Description

Technical Field

[0001] The invention relates to the technical field of chemical vapor deposition devices, and in particular to a microwave plasma chemical vapor deposition device. Background Art

[0002] In recent years, microwave plasma chemical vapor deposition (MPCVD) technology has become increasingly mature, and more and more companies are using this method to produce diamond products. Existing MPCVD equipment generally adopts a single microwave generator, a single antenna and a cylindrical cavity (or a dish-shaped cavity) structure; the principle is that microwaves are guided by three pins, waveguides, and mode converters connected in sequence, and then fed into a closed cylindrical resonant cavity (or a dish-shaped resonant cavity) through the antenna and quartz glass. Special gases flow through the pipes integrated in the antenna into the cavity to participate in the reaction. Under the combined action of microwaves and special gases, diamond products are finally deposited on the sample growth table.

[0003] Existing products all use a circular sample stage and a cylindrical resonant cavity (or a dish-shaped resonant cavity). The cylindrical resonant cavity can form a circular standing wave of appropriate intensity on the surface of the sample stage. The standing wave means that this is an area of ​​high microwave field strength, which can excite the carbon-containing gas above the sample stage to form active carbon-containing groups and atomic hydrogen, and form plasma. Although simply increasing the microwave power can form a high microwave field (without having to form a standing wave), a high microwave field over a large area will lead to high temperatures in irrelevant areas, wasting energy while also making heat dissipation a problem.

[0004] Therefore, it is necessary to provide a microwave plasma chemical vapor deposition device to solve the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide a microwave plasma chemical vapor deposition device to solve the problem that the existing products proposed in the above background technology can form a high microwave field by simply increasing the microwave power (without having to form a standing wave), but the high microwave field over a large area will cause high temperature in irrelevant areas and waste energy.

[0006] Based on the above ideas, the present invention provides the following technical solutions: a microwave plasma chemical vapor deposition device, comprising a microwave generator and three pins connected to the microwave generator, the outlet of the three pins is connected to a mode converter, the other two outlets of the mode converter are respectively connected to a cavity and a short-circuit piston, a growth table is arranged in the cavity, an upper cover is arranged above the cavity, and a special gas channel is installed on the upper cover, characterized in that: a plurality of coaxial linear microwave antennas are installed on both side walls inside the cavity, the microwaves passing through the mode converter can enter the entrance of the coaxial linear microwave antenna, the outlets of the coaxial linear microwave antennas on both sides of the cavity are connected through a quartz channel, and the above-mentioned special gas channel has a plurality of output ends, and each output end is arranged opposite to the quartz channel.

[0007] As a further solution of the present invention: a cooling platform is arranged below the growth platform, a wavy cooling groove is opened on the surface of the cooling platform, a heat dissipation strip is fixedly arranged on the bottom surface of the growth platform, the heat dissipation strip is matched with the shape of the cooling groove, and a water inlet pipe and a drainage pipe are fixedly installed on both sides of the cooling platform, and the water inlet pipe and the drainage pipe are respectively connected to the two ends of the cooling groove.

[0008] As a further solution of the present invention: a guide port is opened on the inner wall of the cooling trough near the drain pipe, so that the coolant in the cooling trough can flow to the drain pipe through the guide port, and a baffle is provided at the guide port, which passes downward through the cooling table and slides with it, and the baffle is located between the heat dissipation strip and the drain pipe and contacts both.

[0009] As a further solution of the present invention: a detection unit is provided at the guide port to detect the flow rate of the coolant in the guide port.

[0010] As a further solution of the present invention: positioning rods are fixedly provided at the four corners of the bottom surface of the growth table, the positioning rods pass downward through the cooling table and slideably cooperate with the cooling table, a fixed block is provided on the outer side of the positioning rod, an electromagnet is installed in the fixed block, a pressure block is slidably installed on the fixed block, a pull plate is fixedly provided at one end of the pressure block away from the positioning rod, the pull plate is made of iron, when the electromagnet is in an energized state, the suction force of the electromagnet on the pull plate can cause the pressure block to approach the positioning rod and press it tightly, and the detection unit is connected to the electromagnet.

[0011] As a further solution of the present invention: the bottom end of the baffle passes through the cavity and is slidably engaged therewith.

[0012] As a further solution of the present invention: a connecting plate is fixedly provided at the bottom end of the baffle plate, a vertical rod is provided at the connecting plate, and the vertical rod passes through the connecting plate and is threadedly engaged with the connecting plate.

[0013] As a further solution of the present invention: the detection unit is installed at the bottom of the cooling platform.

[0014] As a further solution of the present invention: a fixing frame is installed at the bottom of the cooling platform, and the fixing frame is fixedly arranged between the cooling platform and the bottom surface of the cavity.

[0015] As a further solution of the present invention: the fixing block is fixedly installed on the inner wall of the fixing frame.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. In this scheme, the ratio of the growth platform area to the cavity bottom area is large, and the space utilization rate is high. However, in the current circular resonant cavity (or butterfly resonant cavity), no matter how powerful the microwave source or multiple microwave sources are, it is difficult to improve the space utilization rate of the cavity. At the same time, the present invention can be easily expanded, while the cylindrical resonant cavity needs to change the overall size of the cavity. In comparison, the present invention is more advanced and can more flexibly adapt to market demand;

[0018] 2. This device can cool down the growth table through the heat dissipation strips, and on the other hand, the height of the growth table can be adjusted through the cooperation of the heat dissipation strips and the baffles. In the process of active adjustment, it is only necessary to adjust the height of the baffle in the vertical direction. In addition, when the delivery of the coolant fluctuates, the growth table can also move passively in the vertical direction, which is conducive to avoiding the continuous increase of the temperature on the growth table, making the device as a whole safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 is a partial cross-sectional view of the present invention;

[0022] Figure 3 It is a schematic diagram of the quartz channel structure of the present invention;

[0023] Figure 4 is a quartz channel distribution diagram of the present invention;

[0024] Figure 5 It is a schematic diagram of the structure of the water inlet pipe and the drain pipe of the present invention;

[0025] Figure 6 It is a schematic diagram of the cooperation between the heat dissipation strip and the cooling groove of the present invention;

[0026] Figure 7 It is a schematic diagram of the heat dissipation strip structure of the present invention;

[0027] Figure 8It is a schematic diagram of the cooling tank structure of the present invention;

[0028] Fig. 9 It is a schematic diagram of the fixed frame structure of the present invention;

[0029] Fig.10 It is a schematic diagram of the pull plate and the pressing block structure of the present invention;

[0030] Fig.11 It is a schematic diagram of the installation of the detection unit of the present invention.

[0031] In the figure: 1. microwave generator; 2. three pins; 3. mode converter; 4. short-circuit piston; 5. coaxial linear microwave antenna; 6. quartz channel; 7. special gas channel; 8. upper cover; 9. sealing door; 10. observation window; 11. cavity; 12. growth table; 13. plasma; 14. drain pipe; 15. connecting plate; 16. vertical rod; 17. baffle; 18. water inlet pipe; 19. cooling trough; 20. heat dissipation strip; 21. guide port; 22. positioning rod; 23. fixing frame; 24. cooling table; 25. fixing block; 26. pull plate; 27. electromagnet; 28. pressing block; 29. ​​detection unit. DETAILED DESCRIPTION

[0032] like Figure 1-Figure 4 As shown, a microwave plasma chemical vapor deposition device comprises a microwave generator 1, wherein the microwave generator 1 is used to generate microwaves, and the microwave generator 1 is connected to a three-pin 2;

[0033] The three pins 2 adjust the microwave impedance while transmitting the microwaves, and the outlet of the three pins 2 is connected to a mode converter 3;

[0034] The mode converter 3 is used to conduct microwaves. The other two outlets of the mode converter 3 are respectively connected to the coaxial linear microwave antenna 5 in the cavity 11 and the short-circuit piston 4 outside the cavity 11. The cross section of the cavity 11 may be rectangular.

[0035] The short-circuit piston 4 can be used for impedance adjustment;

[0036] In actual use, microwaves pass through the mode converter 3 and the holes on the wall of the cavity 11 and enter the entrance of the coaxial linear microwave antenna 5 installed on the inner wall of the cavity 11. The exits of the coaxial linear microwave antenna 5 on both sides of the cavity 11 are connected through the quartz channel 6, so that the inner side of the coaxial linear microwave antenna 5 is isolated from the space of the cavity 11. After passing through the coaxial linear microwave antenna 5, the microwaves are fed out from the quartz channel 6 and react with the special gas to generate a large area plasma 13 around the quartz channel 6.

[0037] An upper cover 8 is provided above the cavity 11, and a special gas channel 7 for inputting special gas is installed on the upper cover 8. A sealing door 9 is installed on the front side of the cavity 11 to facilitate the placement of seed crystals before the reaction and the removal of products after the reaction. An observation window 10 is installed on the sealing door 9 to observe the growth of diamonds in the cavity 11;

[0038] A growth table 12 is provided in the cavity 11. During actual use, the microwaves generated by the microwave generator 1 are fed into the cavity 11 through the three pins 2, the mode converter 3 and the coaxial linear microwave antenna 5, and a high field strength area is generated around the quartz channel 6. After the gas in the special gas channel 7 reaches the high field strength area, it is excited to form active carbon-containing groups and atomic hydrogen, and a plasma 13 is generated. The generated plasma 13 moves downward, and by connecting multiple groups of coaxial linear microwave antennas 5 at the output port of the converter 3, the number of quartz channels 6 can be expanded, thereby expanding the high field strength domain and the plasma domain. This method can quickly customize equipment of the required size according to customer requirements to meet different market needs. In actual use, the special gas channel 7 has multiple output ends, so that it can correspond to each group of quartz channels 6.

[0039] In this solution, the ratio of the area of ​​the growth platform 12 to the bottom area of ​​the cavity 11 is large, and the space utilization rate is high. However, in the current circular resonant cavity (or butterfly-shaped resonant cavity), no matter how powerful the microwave source or how many microwave sources are used, it is difficult to improve the space utilization rate of the cavity 11. At the same time, the present invention can be easily expanded, while the cylindrical resonant cavity requires changing the overall size of the cavity 11. In comparison, the present invention is more advanced and can more flexibly adapt to market demand.

[0040] like Figure 1-Figure 2 , Figure 5-Figure 11 As shown, in actual use, a cooling platform 24 is provided below the growth platform 12, and a wavy cooling groove 19 is provided on the surface of the cooling platform 24, and a heat dissipation bar 20 is fixedly provided on the bottom surface of the growth platform 12. The heat dissipation bar 20 can be made of copper or aluminum material, and the shape of the heat dissipation bar 20 matches the shape of the cooling groove 19, so that the heat dissipation bar 20 can be inserted into the cooling groove 19 and sealed therewith. Of course, a strip groove matching the shape of the heat dissipation bar 20 can be provided on the outer side of the heat dissipation bar 20, and a sealing strip can be installed in the strip groove to improve the sealing between the heat dissipation bar 20 and the inner wall of the cooling groove 19, refer to Figure 8 As shown, a water inlet pipe 18 and a drain pipe 14 are fixedly installed on both sides of the cooling table 24. The water inlet pipe 18 and the drain pipe 14 are connected to the external water pipe. The water inlet pipe 18 and the drain pipe 14 are respectively connected to the two ends of the cooling trough 19. In actual use, coolant is injected into the cooling trough 19 through the water inlet pipe 18. When the coolant flows between the bottom surface of the heat dissipation strip 20 and the bottom surface of the inner cavity of the cooling trough 19 until it can take away the heat of the heat dissipation strip 20 itself, the growth table 12 is cooled.

[0041] Reference Figure 8 A guide port 21 is provided on the inner wall of the cooling groove 19 near the drain pipe 14, so that the coolant in the cooling groove 19 can flow to the drain pipe 14 through the guide port 21;

[0042] Further, a baffle plate 17 is provided at the guide port 21, and the baffle plate 17 passes downward through the cooling stage 24 and slides with the cooling stage 24. Figure 6 As shown, the baffle 17 is located between the heat dissipation strip 20 and the drain pipe 14 and contacts the two. The baffle 17 can be used to adjust the size of the guide port 21, thereby adjusting the flow rate of the coolant. In actual use, the height of the growth table 12 can be adjusted through this structure. Specifically, when the baffle 17 is driven to move upward relative to the cooling table 24, the cross-section of the guide port 21 will be reduced, thereby hindering the outflow of the coolant, so that the water pressure in the cooling trough 19 increases, thereby driving the heat dissipation strip 20 and the growth table 12 to move upward. Similarly, when the baffle 17 moves downward, the cross-section of the guide port 21 increases, thereby reducing the water pressure in the cooling trough 19. At this time, the growth table 12 can move downward.

[0043] Furthermore, in order to monitor the flow rate of the coolant, a detection unit 29 is provided at the guide port 21. The detection unit 29 may be a flow sensor or a flow meter, etc., and is mainly used to detect the flow rate of the coolant in the guide port 21.

[0044] Reference Figure 7 , Figure 9-10 As shown, positioning rods 22 are fixedly arranged at the four corners of the bottom surface of the growth table 12, and the positioning rods 22 pass downward through the cooling table 24 and slide with it, and a fixing block 25 is arranged on the outer side of the positioning rod 22, and an electromagnet 27 is installed in the fixing block 25, referring to Fig.10 As shown, a pressure block 28 is slidably installed on one side of the fixed block 25 close to the positioning rod 22, and a pull plate 26 is fixedly provided on the end of the pressure block 28 away from the positioning rod 22. The pull plate 26 is made of iron. When the electromagnet 27 is in a powered state, the suction force of the electromagnet 27 on the pull plate 26 can cause the pressure block 28 to approach the positioning rod 22 and press it, thereby locking the growth table 12 in the vertical direction. A controller (such as a PLC or a single-chip microcomputer, etc.) can be connected between the above-mentioned detection unit 29 and the electromagnet 27. In actual use, when the value detected by the detection unit 29 deviates from the preset value, the electromagnet 27 can be caused to be in a de-energized state through the controller.

[0045] For the convenience of description, the flow rate of the coolant through the guide port 21 in the initial state of the baffle plate 17 is defined as the initial flow rate. When the detection unit 29 detects that the coolant flow rate at the guide port 21 is the initial flow rate, the detection unit 29 can cause the electromagnet 27 to be in an energized state through the controller, thereby locking the vertical position of the growth table 12. When it is necessary to adjust the height of the growth table 12, the vertical position of the baffle plate 17 can be adjusted. Specifically, from the above analysis, it can be seen that when the baffle plate 17 moves upward, the cross-section of the guide port 21 will decrease, so that the coolant flow rate at the guide port 21 increases. This signal is captured by the detection unit 29 and the controller causes the electromagnet 27 to be in a de-energized state. At this time, the pressure block 28 will leave the surface of the positioning rod 22, thereby releasing the growth table 12 in the vertical direction. Lock, and when the cross-section of the guide port 21 decreases, the water pressure in the entire cooling groove 19 increases, thereby driving the heat dissipation strip 20 and the growth platform 12 to move upward. In this process, the heat dissipation strip 20 gradually moves away from the top surface of the baffle plate 17, thereby gradually increasing the cross-section of the guide port 21. When the cross-sectional area of ​​the guide port 21 increases to the size of the initial state, the flow rate of the coolant at the guide port 21 returns to the initial flow rate. At this time, the detection unit 29 can cause the electromagnet 27 to be in an energized state, thereby pressing the pressure block 28 against the positioning rod 22, and preventing the growth platform 12 from moving. Similarly, when the baffle plate 17 moves downward, the flow rate of the coolant at the guide port 21 decreases. At this time, the pressure block 28 will leave the positioning rod 22, and the water pressure in the cooling groove 19 decreases, so that the growth platform 12 can move downward;

[0046] In addition to the above effects, when the present solution is in use, when the delivery of the coolant fluctuates, for example, when the flow rate of the coolant decreases due to a decrease in pump power, the cooling effect of the coolant on the growth table 12 is weakened. However, due to the decrease in the flow rate at the guide port 21, the electromagnet 27 is in a de-energized state, so that one end of the pressing block 28 leaves the positioning rod 22. At this time, the growth table 12 will automatically move downward for a distance and away from the plasma 13, thereby avoiding a continuous increase in the temperature of the growth table 12.

[0047] To summarize, this device can cool down the growth table 12 through the heat dissipation strips 20, and on the other hand, can adjust the height of the growth table 12 through the cooperation of the heat dissipation strips 20 and the baffle 17. During the active adjustment process, it is only necessary to adjust the height of the baffle 17 in the vertical direction. In addition, when the delivery of the coolant fluctuates, the growth table 12 can also passively move in the vertical direction, which is beneficial to avoid the temperature on the growth table 12 from continuing to rise, making the device as a whole safer and more reliable.

[0048] Reference Figure 5-Figure 10As shown, the bottom end of the baffle plate 17 passes through the cavity 11 and slides with it, and a connecting plate 15 is fixedly provided at the bottom end of the baffle plate 17, and a vertical rod 16 is provided at the connecting plate 15. Specifically, the vertical rod 16 passes through the connecting plate 15 and threads with it, and the top end of the vertical rod 16 rotates with the cavity 11. This structure is conducive to adjusting the position of the baffle plate 17 in the vertical direction. Of course, the baffle plate 17 can also be adjusted electrically.

[0049] The water inlet pipe 18 and the drain pipe 14 pass through the cavity 11 and are fixedly connected thereto. A fixing frame 23 is installed at the bottom of the cooling platform 24 . The fixing frame 23 is fixedly disposed between the cooling platform 24 and the bottom surface of the cavity 11 .

[0050] The fixing block 25 is fixedly mounted on the inner wall of the fixing frame 23. Fig.10 As shown, the interior of the fixed block 25 is a cavity structure, the electromagnet 27 is fixedly arranged in the cavity, and the pull plate 26 is arranged on the side of the electromagnet 27 away from the positioning rod 22. The electromagnet 27 can be an annular structure, and a spring is fixedly arranged between the pull plate 26 and the inner end surface of the fixed frame 23. Through this structure, when the electromagnet 27 is in an energized state, the pull plate 26 can be adsorbed, thereby prompting the pressure block 28 to be ejected and pressed against the positioning rod 22.

[0051] like Fig.11 The figure shows the installation position of the detection unit 29. In actual use, the detection unit 29 can be installed at the bottom of the cooling platform 24. Specifically, a mounting groove can be opened on the bottom surface of the cooling platform 24, and the detection unit 29 can be placed in the mounting groove so that the input end of the detection unit 29 is arranged opposite to the guide port 21. Through this structure, the coolant flow rate at the guide port 21 can be monitored. Of course, the specific installation position of the detection unit 29 is not limited to this. In actual use, it can also be installed on the drain pipe 14 as needed.

Claims

1. A microwave plasma chemical vapor deposition device, comprising a microwave generator and three pins connected to the microwave generator, wherein the outlet of the three pins is connected to a mode converter, and the other two outlets of the mode converter are respectively connected to a cavity and a short-circuit piston, a growth platform is arranged in the cavity, an upper cover is arranged above the cavity, and a special gas channel is installed at the upper cover, characterized in that: A plurality of coaxial linear microwave antennas are installed on both side walls of the cavity, and microwaves passing through the mode converter can enter the entrance of the coaxial linear microwave antenna. The outlets of the coaxial linear microwave antennas on both sides of the cavity are connected through a quartz channel. The above-mentioned special gas channel has a plurality of output ends, and each output end is arranged opposite to the quartz channel; A cooling platform is arranged below the growth platform, a wave-shaped cooling groove is provided on the surface of the cooling platform, a heat dissipation strip is fixedly arranged on the bottom surface of the growth platform, the heat dissipation strip matches the shape of the cooling groove, and a water inlet pipe and a drainage pipe are fixedly installed on both sides of the cooling platform, and the water inlet pipe and the drainage pipe are respectively connected to the two ends of the cooling groove; A guide port is provided at the inner wall of the cooling groove near the drain pipe, so that the coolant in the cooling groove can flow to the drain pipe through the guide port, and a baffle is provided at the guide port, which passes downward through the cooling platform and slides with it, and the baffle is located between the heat dissipation strip and the drain pipe and contacts the two; The guide port is provided with a detection unit for detecting the flow rate of the coolant in the guide port; Positioning rods are fixedly provided at the four corners of the bottom surface of the growth table. The positioning rods pass downward through the cooling table and slide with it. A fixed block is provided on the outer side of the positioning rod. An electromagnet is installed in the fixed block. A pressure block is slidably installed on the fixed block. A pulling plate is fixedly provided at the end of the pressure block away from the positioning rod. The pulling plate is made of iron. When the electromagnet is in an energized state, the suction force of the electromagnet on the pulling plate can cause the pressure block to approach the positioning rod and press it tightly. The detection unit is connected to the electromagnet.

2. The microwave plasma chemical vapor deposition device according to claim 1, characterized in that: The bottom end of the baffle plate passes through the cavity and is slidably matched with the cavity.

3. The microwave plasma chemical vapor deposition device according to claim 1, characterized in that: A connecting plate is fixedly arranged at the bottom end of the baffle plate, and a vertical rod is arranged at the connecting plate. The vertical rod passes through the connecting plate and is threadably engaged with the connecting plate.

4. The microwave plasma chemical vapor deposition device according to claim 1, characterized in that: The detection unit is installed at the bottom of the cooling stage.

5. The microwave plasma chemical vapor deposition device according to claim 1, characterized in that: A fixing frame is installed at the bottom of the cooling platform, and the fixing frame is fixedly arranged between the cooling platform and the bottom surface of the cavity.

6. The microwave plasma chemical vapor deposition device according to claim 5, characterized in that: The fixing block is fixedly installed on the inner wall of the fixing frame.

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