SiC single crystal growth furnace induction coil lifting adjusting system

Abstract

The utility model discloses a SiC single crystal growth furnace induction coil lifting adjusting system which comprises a low-speed transmission mechanism and a quick transmission mechanism, the low-speed transmission mechanism and the quick transmission mechanism are horizontally arranged on a mounting plate in parallel, and the low-speed transmission mechanism comprises a first motor, a planetary reducer, a harmonic reducer and a first electromagnetic clutch; the quick transmission mechanism comprises a second motor and a second electromagnetic clutch; the straight line where the output ends of the first electromagnetic clutch and the second electromagnetic clutch are located is perpendicular to the straight line where the rapid transmission mechanism is located, the output ends of the first electromagnetic clutch and the second electromagnetic clutch are both provided with synchronous belt wheels, the two synchronous belt wheels are provided with synchronous belts, and one synchronous belt wheel is connected with a right-angle speed reducer. The output end of the right-angle speed reducer is connected with the induction coil lifting mechanism so as to drive the induction coil to ascend and descend. According to the lifting device, the induction coil can be lifted at an extremely low lifting speed, the stability is good in the lifting process of the induction coil, and the growth quality of silicon carbide crystals is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of new materials, relates to silicon carbide, and specifically relates to a lifting and lowering regulating system of an induction coil of a SiC single crystal growth furnace. Background Art

[0002] Some fields have increasingly higher requirements for the performance indicators and reliability of power semiconductor devices, requiring devices to have higher operating voltages, greater current carrying capacity, higher operating frequencies, higher efficiency, higher operating temperatures, stronger heat dissipation capabilities, and higher reliability. Therefore, the development of third-generation semiconductor materials represented by silicon carbide (SiC) has begun to receive attention.

[0003] At present, physical vapor transport (PVT) is one of the mainstream methods for preparing silicon carbide (SiC) crystals. The PVT method grows SiC single crystals. Usually, SiC crystals are placed on the top of a graphite crucible as seed crystals, and Si and C powders are placed on the bottom of a graphite crucible as source materials. An induction coil is designed for heating, and the temperature reaches about 2300°C. The growth temperature gradient is controlled, and argon gas is introduced to control the pressure in the growth chamber. During the crystal growth process, the seed crystal is attached to the top with a lower temperature, and the SiC source temperature at the bottom is higher, and there is a certain temperature gradient between the two. During the crystal growth process, the source material sublimates into a gas phase substance and crystallizes on the seed crystal at the cold end, and a SiC single crystal is obtained.

[0004] Thermal field control is the core of the PVT growth process and has a decisive influence on the quality of the grown silicon carbide crystals. In order to improve the utilization rate of silicon carbide powder and enable the powder at the bottom of the graphite pile to be transported up, it is necessary to adjust the distribution of the thermal field during the growth process, and slowly move the high-temperature area downward as the powder is consumed. In actual production, a common method is to change the thermal field distribution in the graphite pile by adjusting the lifting of the induction coil. During the silicon carbide crystal growth process, the coil lifting is required to operate at an extremely low speed and extremely high precision, less than or equal to 0.05mm / h. During the loading process, the induction coil is often adjusted to different initial positions according to different process requirements. In order to improve work efficiency, the induction coil is required to move at a faster speed, such as 0.8 mm / h.

[0005] The existing lifting and lowering adjustment system is connected to the lifting mechanism of the induction coil, and the lifting mechanism is driven to drive the induction coil to lift and lower. However, the minimum lifting speed of the existing lifting and lowering adjustment system can only reach 0.5 mm / h, and the lifting and lowering of the induction coil cannot be achieved at an extremely low lifting speed, which affects the growth quality of the silicon carbide crystal, and the stability of the induction coil during the lifting process is poor. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an induction coil lifting and adjusting system for a SiC single crystal growth furnace. The present invention can lift the induction coil at an extremely low lifting speed, and has good stability during the lifting process of the induction coil, thereby improving the growth quality of silicon carbide crystals.

[0007] The technical solution of the utility model is achieved in this way:

[0008] A lifting and adjusting system for an induction coil of a SiC single crystal growth furnace comprises a low-speed transmission mechanism and a fast transmission mechanism, wherein the low-speed transmission mechanism and the fast transmission mechanism are horizontally arranged in parallel on a mounting plate.

[0009] The low-speed transmission mechanism includes a first motor, a planetary reducer, a harmonic reducer and a first electromagnetic clutch. The output end of the first motor is connected to the input end of the planetary reducer, the output end of the planetary reducer is connected to the input end of the harmonic reducer, and the output end of the harmonic reducer is connected to the input end of the first electromagnetic clutch.

[0010] The rapid transmission mechanism comprises a second motor and a second electromagnetic clutch, wherein an output end of the second motor is connected to an input end of the second electromagnetic clutch.

[0011] The straight line where the output ends of the first electromagnetic clutch and the second electromagnetic clutch are located is perpendicular to the straight line where the rapid transmission mechanism is located, and the output ends of the first electromagnetic clutch and the second electromagnetic clutch are both provided with synchronous pulleys, and synchronous belts are provided on the two synchronous pulleys, one of the synchronous pulleys is connected to a right-angle reducer, and the output end of the right-angle reducer is connected to the induction coil lifting mechanism to drive the induction coil to lift.

[0012] Furthermore, a permanent magnet brake is provided at the input end of the right-angle reducer, the input end of the permanent magnet brake is connected to the synchronous pulley, and the output end of the permanent magnet brake is connected to the input end of the right-angle reducer.

[0013] Furthermore, a bearing seat is provided on the mounting plates corresponding to the output ends of the first electromagnetic clutch and the second electromagnetic clutch, and a bearing is provided on the bearing seat for supporting the output shafts of the first electromagnetic clutch and the second electromagnetic clutch.

[0014] Furthermore, bearing seats are provided on the corresponding mounting plates between the planetary reducer and the harmonic reducer, and between the harmonic reducer and the first electromagnetic clutch, and bearings are provided on the bearing seats, which are respectively used to support the output shaft of the planetary reducer and the output shaft of the harmonic reducer, thereby ensuring the coaxiality of the harmonic reducer and the first electromagnetic clutch.

[0015] Furthermore, it also includes a controller and an encoder. The encoder is arranged on the lifting mechanism and is located at one end of the lifting mechanism away from the right-angle reducer, and is used to monitor the rotational speed of the lifting mechanism. The encoder, the first motor and the second motor are all connected to the controller, so that the controller can control the opening and closing and power of the first motor and the second motor according to the rotational speed monitored by the encoder.

[0016] Furthermore, the mounting plate is provided with a plurality of mounting holes and leveling holes, the mounting holes are used to install and fix the mounting plate, and the leveling holes are used to adjust the horizontality of the mounting plate.

[0017] Furthermore, the first motor is a servo motor.

[0018] Furthermore, the second motor is a stepping motor.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] 1. The utility model is provided with a low-speed transmission mechanism and a fast transmission mechanism. The low-speed transmission mechanism is used in the growth process of silicon carbide crystals, and a harmonic reducer is arranged at the output end of the planetary reducer, which can realize the lifting and lowering of the induction coil at an extremely low lifting speed. The low-speed transmission mechanism of the utility model can achieve a lifting speed of 0.02mm / h, which is beneficial to the growth quality of silicon carbide crystals; the fast transmission mechanism is used when replacing materials or maintenance and overhaul, which can effectively improve work efficiency.

[0021] 2. The utility model sets a permanent magnet brake at the input end of the right-angle reducer, which can be closed in an emergency to stop the induction coil from rising and falling, thereby improving safety.

[0022] 3. The utility model can correct the rotation speed of the low-speed transmission mechanism and the fast transmission mechanism in real time by setting an encoder, forming a negative feedback effect to increase the lifting stability and accuracy of the induction coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 -Structural schematic diagram of the utility model.

[0024] Among them: 1-servo motor; 2-planetary reducer; 3-harmonic reducer; 4-first electromagnetic clutch; 5-permanent magnet brake; 6-right angle reducer; 7-stepping motor; 8-second electromagnetic clutch; 9 synchronous belt; 10-mounting plate; 11-lifting module; 12-module mounting plate; 13-coil support structure; 14-encoder; 15-guide column; 16-vacuum chamber. DETAILED DESCRIPTION

[0025] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] See also Figure 1 A SiC single crystal growth furnace induction coil lifting and adjusting system includes a low-speed transmission mechanism and a fast transmission mechanism, and the low-speed transmission mechanism and the fast transmission mechanism are horizontally arranged in parallel on a mounting plate 10.

[0027] The low-speed transmission mechanism includes a servo motor 1, a planetary reducer 2, a harmonic reducer 3 and a first electromagnetic clutch 4. The output end of the servo motor 1 is connected to the input end of the planetary reducer 2, the output end of the planetary reducer 2 is connected to the input end of the harmonic reducer 3, and the output end of the harmonic reducer 3 is connected to the input end of the first electromagnetic clutch 4.

[0028] The rapid transmission mechanism comprises a stepper motor 7 and a second electromagnetic clutch 8 , wherein an output end of the stepper motor 7 is connected to an input end of the second electromagnetic clutch 8 .

[0029] The straight line where the output ends of the first electromagnetic clutch 4 and the second electromagnetic clutch 8 are located is perpendicular to the straight line where the fast transmission mechanism is located, and is also perpendicular to the straight line where the low-speed transmission mechanism is located, and the output ends of the first electromagnetic clutch 4 and the second electromagnetic clutch 8 are both provided with synchronous pulleys, and synchronous belts 9 are provided on the two synchronous pulleys, one of the synchronous pulleys is connected to a right-angle reducer 6, and the output end of the right-angle reducer 6 is connected to the induction coil lifting mechanism to drive the induction coil to lift.

[0030] In this embodiment, the right-angle reducer is on the synchronous pulley corresponding to the low-speed transmission mechanism. When the low-speed transmission mechanism is running, the first electromagnetic clutch is energized, and the first electromagnetic clutch transmits the torque of the low-speed transmission mechanism, and the second electromagnetic clutch is not energized, keeping the stepper motor idling; when the fast transmission mechanism is running, the second electromagnetic clutch is energized, and the second electromagnetic clutch transmits the torque of the fast transmission mechanism through the synchronous belt and synchronous pulley structure, and the first electromagnetic clutch is not energized, keeping the servo motor idling; the transmitted torque is transmitted to the lifting mechanism through the right-angle reducer to realize the lifting of the induction coil.

[0031] Here, a harmonic reducer is arranged at the output end of the planetary reducer, which can realize the lifting and lowering of the induction coil at an extremely low lifting speed. In this embodiment, the extremely low speed can reach 0.02mm / h, thereby effectively improving the growth quality of silicon carbide crystals.

[0032] During specific implementation, a permanent magnet brake 5 is provided at the input end of the right-angle reducer 6 , the input end of the permanent magnet brake 5 is connected to the synchronous pulley, and the output end of the permanent magnet brake 5 is connected to the input end of the right-angle reducer 6 .

[0033] A permanent magnetic brake is provided here, which can be turned off in an emergency to stop the induction coil from being raised or lowered, thereby improving safety. When the induction coil is to be raised or lowered, the permanent magnetic brake is in an energized state, and the induction coil is raised or lowered through a low-speed transmission mechanism or a fast transmission mechanism.

[0034] In specific implementation, a bearing seat is provided on the mounting plate 10 corresponding to the output ends of the first electromagnetic clutch 4 and the second electromagnetic clutch 8 , and a bearing is provided on the bearing seat for supporting the output shafts of the first electromagnetic clutch 4 and the second electromagnetic clutch 8 .

[0035] Bearing seats are provided on the corresponding mounting plates 10 between the planetary reducer 2 and the harmonic reducer 3, and between the harmonic reducer 3 and the first electromagnetic clutch 4, and bearings are provided on the bearing seats, which are respectively used to support the output shaft of the planetary reducer 2 and the output shaft of the harmonic reducer 3, thereby ensuring the coaxiality of the harmonic reducer 3 and the first electromagnetic clutch 4.

[0036] In a specific implementation, it also includes a controller (not shown in the figure) and an encoder 14. The encoder 14 is arranged on the lifting mechanism and is located at one end of the lifting mechanism away from the right-angle reducer 6, and is used to monitor the rotation speed of the lifting mechanism. The encoder 14, the servo motor 1 and the stepper motor 7 are all connected to the controller, so that the controller can control the opening and closing and power of the servo motor and the stepper motor according to the rotation speed monitored by the encoder 14.

[0037] like Figure 1 As shown, the lifting mechanism includes a vertically arranged lifting module 11 and a module mounting plate 12. The lifting module 11 is connected to the output end of the right-angle reducer 6 to facilitate the rotation of the lifting module, so as to drive the module mounting plate to lift. The induction coil is arranged on the outer wall of the vacuum chamber 16 through the coil support structure 13. A number of guide posts 15 are vertically distributed around the outer side of the vacuum chamber 16. The coil support structure 13 is provided with a number of guide holes. The guide posts are vertically inserted into a number of guide holes located on the same straight line. At the same time, the module mounting plate is fixed to the coil support structure. When the module mounting plate is lifted or lowered, the coil support structure is lifted or lowered, thereby realizing the lifting of the induction coil. In this embodiment, the lifting module is a screw rod, the lower end of which is connected to the output end of the right-angle reducer, and the top end of the screw rod is connected to the encoder through a coupling. In this way, when there is a problem with the screw rod speed, the encoder can correct it in real time, forming a negative feedback effect to increase the lifting stability and accuracy of the induction coil.

[0038] During specific implementation, the mounting plate 10 is provided with a plurality of mounting holes and leveling holes. The mounting holes are used to install and fix the mounting plate 10 , and the leveling holes are used to adjust the levelness of the mounting plate 10 .

[0039] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A SiC single crystal growth furnace induction coil lifting and adjusting system, characterized in that: It comprises a low-speed transmission mechanism and a fast transmission mechanism, which are arranged horizontally and in parallel on a mounting plate; The low-speed transmission mechanism includes a first motor, a planetary reducer, a harmonic reducer and a first electromagnetic clutch, wherein the output end of the first motor is connected to the input end of the planetary reducer, the output end of the planetary reducer is connected to the input end of the harmonic reducer, and the output end of the harmonic reducer is connected to the input end of the first electromagnetic clutch; The rapid transmission mechanism comprises a second motor and a second electromagnetic clutch, wherein the output end of the second motor is connected to the input end of the second electromagnetic clutch; The straight line where the output ends of the first electromagnetic clutch and the second electromagnetic clutch are located is perpendicular to the straight line where the rapid transmission mechanism is located, and the output ends of the first electromagnetic clutch and the second electromagnetic clutch are both provided with synchronous pulleys, and synchronous belts are provided on the two synchronous pulleys, one of the synchronous pulleys is connected to a right-angle reducer, and the output end of the right-angle reducer is connected to the induction coil lifting mechanism to drive the induction coil to lift.

2. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1, characterized in that: The input end of the right-angle reducer is provided with a permanent magnet brake, the input end of the permanent magnet brake is connected to the synchronous pulley, and the output end of the permanent magnet brake is connected to the input end of the right-angle reducer.

3. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1 or 2, characterized in that: A bearing seat is provided on the mounting plate corresponding to the output ends of the first electromagnetic clutch and the second electromagnetic clutch, and a bearing is provided on the bearing seat for supporting the output shafts of the first electromagnetic clutch and the second electromagnetic clutch.

4. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 3, characterized in that: Bearing seats are provided on the corresponding mounting plates between the planetary reducer and the harmonic reducer, and between the harmonic reducer and the first electromagnetic clutch, and bearings are provided on the bearing seats, which are respectively used to support the output shaft of the planetary reducer and the output shaft of the harmonic reducer to ensure the coaxiality of the harmonic reducer and the first electromagnetic clutch.

5. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1, characterized in that: It also includes a controller and an encoder. The encoder is arranged on the lifting mechanism and is located at one end of the lifting mechanism away from the right-angle reducer, and is used to monitor the rotational speed of the lifting mechanism. The encoder, the first motor and the second motor are all connected to the controller, so that the controller can control the opening and closing and power of the first motor and the second motor according to the rotational speed monitored by the encoder.

6. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1, characterized in that: The mounting plate is provided with a plurality of mounting holes and leveling holes, wherein the mounting holes are used for mounting and fixing the mounting plate, and the leveling holes are used for adjusting the horizontality of the mounting plate.

7. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1, characterized in that: The first motor is a servo motor.

8. The SiC single crystal growth furnace induction coil lifting and adjusting system according to claim 1, characterized in that: The second motor is a stepping motor.

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