Thermal field structure for preparing silicon carbide crystals

Abstract

The utility model discloses a thermal field structure for preparing silicon carbide crystals, which comprises a case and an outer support sleeve fixed at the top end of the case, a graphite end cover is bolted at the top end of the outer support sleeve, a conical case is fixed at the bottom end of the outer support sleeve, a protective sleeve is fixed inside the conical case, and the protective sleeve is fixed at the bottom end of the outer support sleeve. An inner steel container is fixed in the outer supporting sleeve, and an electromagnetic heating type graphite crucible is installed in the inner steel container in a sliding mode. The symmetrical worm and gear transmission structure and the conical fluted disc two-way transmission structure can evenly distribute loads, reduce unbalance and friction in the moving process, improve the stability and durability of a lifting system, enable mechanical parts not to be affected by thermal expansion and deformation even if the lifting system operates for a long time and is in the high-temperature and high-pressure environment, and improve the service life of the lifting system. And the stability and the accuracy of the lifting motion of the electromagnetic heating type graphite crucible are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of silicon carbide crystal preparation equipment, in particular to a thermal field structure for preparing silicon carbide crystals. Background Art

[0002] The PVT method is a commonly used crystal growth method, which uses raw materials in the gas phase to deposit and crystallize on a crystal substrate under high temperature and high pressure conditions to grow the desired crystal. In the growth process of silicon carbide crystals, the thermal field structure plays a vital role, which includes factors such as temperature distribution, thermal convection, and thermal radiation. In the PVT method, a silicon carbide substrate is usually used as the growth substrate of the crystal. The raw material gas (such as silane and methane) is decomposed under high temperature and high pressure conditions and deposited on the substrate surface to form silicon carbide crystals. In this process, the thermal field structure has a significant impact on the temperature control, impurity diffusion, and crystal quality during the crystal growth process. The design and optimization of the thermal field structure (generally a graphite crucible) can ensure the uniform distribution of temperature in the crystal growth area, avoid excessive temperature gradients, and thus ensure the uniformity and stability of crystal growth;

[0003] As disclosed in the authorization announcement number CN115323490B, a graphite thermal field single crystal growth device for preparing silicon carbide crystals includes a growth tank body and a detachable top cover installed on the top surface thereof, an exhaust fan housing is installed in the middle position of the top surface of the detachable top cover, a crucible body is arranged in the inner cavity of the growth tank body, an installation chamber is separated by a partition at the lower part of the inner cavity of the growth tank body, a servo motor is installed on the bottom wall of the installation chamber, the longitudinal output shaft of the servo motor is connected to a lifting aluminum plate through a screw lifting assembly, and the crucible body is placed on the top surface of the lifting aluminum plate, which enables the servo motor to operate in the installation chamber, drive the screw lifting assembly, and Under the action of the component, the lifting aluminum plate is driven to be lifted and lowered in the growth tank body, and the crucible body is driven to be lifted and lowered at the same time, so as to facilitate the taking of the crucible body. However, the technical solution mainly achieves the purpose of lifting through the screw lifting component. In actual operation, the transmission accuracy of the screw lifting component is affected by many factors, such as parts processing accuracy, lubrication conditions, ambient temperature, etc., which leads to inaccurate position control during the lifting process, affecting the stability and accuracy of the growth tank body and the crucible body. Especially under long-term operation and high temperature and high pressure environment, mechanical parts are easily affected by thermal expansion and deformation, which in turn affects the smoothness and accuracy of the movement. Utility Model Content

[0004] The purpose of the utility model is to provide a thermal field structure for preparing silicon carbide crystals, which uses a stepping motor and a reducer as a driving source, and cooperates with symmetrical gear plate lifting structure, worm gear transmission structure and other components to realize the lifting and removal function of an electromagnetic heating graphite crucible, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a thermal field structure for preparing silicon carbide crystals, comprising a chassis and an outer support sleeve fixed at the top of the chassis, wherein the top of the outer support sleeve is bolted with a graphite end cap, the bottom of the outer support sleeve is fixed with a conical housing, and the interior of the conical housing is fixed with a protective sleeve, the interior of the outer support sleeve is fixed with an inner steel liner, and an electromagnetically heated graphite crucible is slidably installed inside the inner steel liner, and the two sides of the bottom of the protective sleeve are symmetrically installed with a plurality of electromagnetically heated graphite crucibles for driving the electromagnetically heated graphite crucible to move in the Z-axis direction. A gear tooth plate lifting structure is provided for driving the two worm gear transmission structures, and worm gear transmission structures for power connection with the gear tooth plate lifting structure are installed on both inner walls of the protective sleeve; a rotation driving source is installed on one side of the bottom end of the conical casing, and a main transmission shaft is installed on the output end of the rotation driving source; the top end of the main transmission shaft extends to the inside of the protective sleeve and is installed with a bevel toothed disc bidirectional transmission structure for driving the two worm gear transmission structures to work synchronously and reversely; a PLC control panel electrically connected to the rotation driving source and the input end of the electromagnetic heating graphite crucible is installed on the outer wall of one side of the chassis.

[0006] Preferably, a support ring is fixed to one end inside the outer support sleeve, and the top end of the support ring and the bottom end of the graphite end cover are in contact with each other.

[0007] Preferably, a lower flange is fixed to one end of the surface of the outer support sleeve, and an upper flange bolted to the lower flange is provided on the outer edge of the top end of the graphite end cover.

[0008] Preferably, a ceramic insulation sleeve for covering the outer support sleeve is fixed to the top of the chassis.

[0009] Preferably, the electromagnetic heating graphite crucible comprises a double-layer graphite crucible slidably mounted inside an inner steel liner, and a first cavity and a second cavity arranged inside the double-layer graphite crucible, wherein a steel sleeve and an electromagnetic coil are respectively installed inside the first cavity and the second cavity.

[0010] Preferably, the rotation driving source includes a stepper motor installed on one side of the bottom end of the conical housing, and a reducer installed on the output end of the stepper motor, and the main transmission shaft is installed on the output shaft of the reducer.

[0011] Preferably, the gear tooth plate lifting structure includes a vertical frame fixed to one side of the bottom of the conical casing, and a circular tooth frame slidably installed on the inner wall of one side of the vertical frame, the top of the circular tooth frame is fixedly connected to the bottom end of the electromagnetic heating graphite crucible, and a secondary shaft is rotatably installed on the outer wall of one side of the vertical frame close to the vertical center line of the conical casing, and driving gears are fixed at both ends of the surface of the secondary shaft, and the driving gear and the circular tooth frame are meshed with each other.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows: the thermal field structure for preparing silicon carbide crystals is provided with structures that cooperate with each other, such as a rotary drive and a gear plate lifting structure, and a stepper motor and a reducer are used as driving sources. Under the control of a PLC control panel, more precise and stable lifting control can be achieved, and the symmetrical worm gear transmission structure and the bevel gear disc bidirectional transmission structure can evenly distribute the load, reduce imbalance and friction during movement, and improve the stability and durability of the lifting system. Even under long-term operation and high-temperature and high-pressure environments, the mechanical parts will not be affected by thermal expansion and deformation, thereby ensuring the smoothness and accuracy of the lifting movement of the electromagnetically heated graphite crucible. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a three-dimensional structural schematic diagram of the utility model;

[0014] Figure 2 This is a schematic diagram of the main cross-sectional structure of the utility model;

[0015] Figure 3 It is a three-dimensional cross-sectional structural schematic diagram of the utility model;

[0016] Figure 4 It is a three-dimensional structural schematic diagram of the gear tooth plate lifting structure of the utility model;

[0017] In the figure: 1. chassis; 2. PLC control panel; 3. outer support sleeve; 301. lower flange edge; 302. ceramic insulation sleeve; 4. graphite end cover; 401. upper flange edge; 5. support ring; 6. conical casing; 7. stepper motor; 8. reducer; 9. main transmission shaft; 10. inner steel liner; 11. electromagnetic heating graphite crucible; 1101. double-layer graphite crucible; 1102. first cavity; 1103. second cavity; 1104. steel sleeve; 1105. electromagnetic coil; 12. protective sleeve; 13. gear tooth plate lifting structure; 1301. vertical frame; 1302. circular tooth frame; 1303. secondary shaft; 1304. driving gear; 14. bevel tooth disc bidirectional transmission structure; 15. worm gear transmission structure. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] See also Figure 1-4 The utility model provides an embodiment: a thermal field structure for preparing silicon carbide crystals, comprising a chassis 1 and an outer support sleeve 3 fixed at the top of the chassis 1, and a graphite end cap 4 is bolted to the top of the outer support sleeve 3, a conical housing 6 is fixed to the bottom of the outer support sleeve 3, and a protective sleeve 12 is fixed inside the conical housing 6, an inner steel bladder 10 is fixed inside the outer support sleeve 3, and an electromagnetically heated graphite crucible 11 is slidably installed inside the inner steel bladder 10, and gear tooth plates for driving the electromagnetically heated graphite crucible 11 to move in the Z-axis direction are symmetrically installed on both sides of the bottom of the protective sleeve 12. A worm gear transmission structure 15 for power connection with the gear plate lifting structure 13 is installed on both inner walls of the protective cover 12, a rotation drive source is installed on one side of the bottom end of the conical casing 6, and a main transmission shaft 9 is installed on the output end of the rotation drive source. The top end of the main transmission shaft 9 extends to the inside of the protective cover 12 and is installed with a bevel gear disc bidirectional transmission structure 14 for driving the two worm gear transmission structures 15 to work synchronously and reversely. A PLC control panel 2 electrically connected to the rotation drive source and the input end of the electromagnetic heating graphite crucible 11 is installed on the outer wall of one side of the chassis 1;

[0020] The rotation driving source includes a stepper motor 7 installed on one side of the bottom end of the conical housing 6, and a reducer 8 installed on the output end of the stepper motor 7. The main transmission shaft 9 is installed on the output shaft of the reducer 8. The stepper motor 7 has a precise stepping angle and good control performance, which can realize precise control of the lifting process and improve the accuracy and stability of the lifting. The function of the reducer 8 is to convert the high-speed rotation of the stepper motor 7 into a lower speed but greater torque output, thereby increasing the carrying capacity and stability of the lifting component;

[0021] A lower flange 301 is fixed to one end of the surface of the outer support sleeve 3, and an upper flange 401 is provided on the outer edge of the top end of the graphite end cover 4, which is bolted to the lower flange 301. A support ring 5 is fixed to one end of the inner part of the outer support sleeve 3, and the top end of the support ring 5 and the bottom end of the graphite end cover 4 are in contact with each other. The outer support sleeve 3 and the graphite end cover 4 are bolted and sealed by the upper flange 401 and the lower flange 301, so that the outer support sleeve 3 is in a sealed state. When the graphite end cover 4 is installed, the bottom end of the graphite end cover 4 is supported by the support ring 5.

[0022] A ceramic insulation sleeve 302 for covering the outer support sleeve 3 is fixed to the top of the chassis 1. The inner steel liner 10 and the ceramic insulation sleeve 302 can provide good heat insulation effect, prevent heat loss, and improve heating efficiency. Especially in a high temperature environment, it can effectively reduce heat loss and keep the internal temperature of the electromagnetic heating graphite crucible 11 stable.

[0023] The electromagnetic heating graphite crucible 11 comprises a double-layer graphite crucible 1101 slidably mounted inside the inner steel bladder 10, and a first cavity 1102 and a second cavity 1103 arranged inside the double-layer graphite crucible 1101, wherein a steel sleeve 1104 and an electromagnetic coil 1105 are respectively installed inside the first cavity 1102 and the second cavity 1103;

[0024] The double-layer graphite crucible 1101 is responsible for accommodating and heating the crystal growth material, and the electromagnetic coil 1105 generates a magnetic field by applying current, and the steel sleeve 1104 generates Joule heating effect under the action of the electromagnetic field, that is, the inside of the double-layer graphite crucible 1101 generates heat, and the heating speed is fast and the heating is uniform. The heating process can be precisely controlled by adjusting the current, so that the crystal growth material inside the pot can be evenly heated, avoiding the problem of uneven crystal growth or morphological distortion caused by excessive temperature gradient;

[0025] The gear plate lifting structure 13 includes a vertical frame 1301 fixed to one side of the bottom of the conical housing 6, and a circular gear frame 1302 slidably installed on the inner wall of one side of the vertical frame 1301. The top of the circular gear frame 1302 is fixedly connected to the bottom end of the electromagnetic heating graphite crucible 11. A secondary shaft 1303 is rotatably installed on the outer wall of one side of the vertical frame 1301 close to the vertical center line of the conical housing 6. Both ends of the surface of the secondary shaft 1303 are fixed with driving gears 1304. The driving gear 1304 and the circular gear frame 1302 mesh with each other. During the movement of the gear plate lifting structure 13, the rotational power of the main transmission shaft 9 is transmitted to the worm gear transmission structure 15 through the bevel gear plate bidirectional transmission structure 14, and the worm gear transmission structure 15 drives the secondary shaft 1303 and the driving gear 1304 to rotate, and the driving gear 1304 is used to drive the circular gear frame 1302 and the electromagnetic heating type graphite crucible 11 to be lifted and lowered. By realizing the lifting and removing function of the electromagnetic heating type graphite crucible 11, the crucible can be replaced and the sample can be taken out more conveniently.

[0026] When the embodiment of the present application is in use, the staff first pours silicon carbide powder into the interior of the electromagnetic heating graphite crucible 11, and covers the graphite end cover 4 with silicon carbide seed crystals, then evacuates the interior of the electromagnetic heating graphite crucible 11, introduces protective gas, and gradually increases the pressure. During this process, the staff turns on the electromagnetic heating graphite crucible 11 for heating through the PLC control panel 2, so that a thermal field structure is generated inside the electromagnetic heating graphite crucible 11, so that the silicon carbide powder grows in the electromagnetic heating graphite crucible 11 and obtains silicon carbide crystals. After the silicon carbide crystals are formed, the staff releases the bolted connection between the outer support sleeve 3 and the graphite end cover 4, and then the staff turns on the stepper motor 7 through the PLC control panel 2 to work, so that the rotational power of the stepper motor 7 is transmitted to the main transmission shaft 9 through the reducer 8, and the main transmission shaft 9 and the bevel gear bidirectional transmission structure 14 are used to drive the two symmetrical worm gears. The transmission structure 15 works synchronously, and then the worm gear transmission structure 15 drives the gear tooth plate lifting structure 13 to move, so that the gear tooth plate lifting structure 13 drives the electromagnetic heating graphite crucible 11 to move upward until the open end of the electromagnetic heating graphite crucible 11 protrudes to the outside of the outer support sleeve 3. At this time, the staff can take the silicon carbide crystals in the electromagnetic heating graphite crucible 11. In this process, the stepper motor 7 and the reducer 8 are used as driving sources. Under the control of the PLC control panel 2, more precise and stable lifting control can be achieved, and the symmetrical worm gear transmission structure 15 and the bevel gear disc bidirectional transmission structure 14 can evenly distribute the load, reduce the imbalance and friction during the movement, and improve the stability and durability of the lifting system. Even under long-term operation and high temperature and high pressure environment, the mechanical parts will not be affected by thermal expansion and deformation, thereby ensuring the smoothness and accuracy of the lifting movement of the electromagnetic heating graphite crucible 11.

Claims

1. A thermal field structure for preparing silicon carbide crystals, characterized in that: The invention comprises a chassis (1) and an outer support sleeve (3) fixed at the top of the chassis (1), wherein the top of the outer support sleeve (3) is bolted with a graphite end cover (4), a conical housing (6) is fixed at the bottom of the outer support sleeve (3), and a protective sleeve (12) is fixed inside the conical housing (6), an inner steel bladder (10) is fixed inside the outer support sleeve (3), and an electromagnetically heated graphite crucible (11) is slidably installed inside the inner steel bladder (10), and gear tooth plate lifting structures (13) for driving the electromagnetically heated graphite crucible (11) to move in the Z-axis direction are symmetrically installed on both sides of the bottom of the protective sleeve (12), and the A worm gear transmission structure (15) which is power-connected to the gear tooth plate lifting structure (13) is installed on both inner walls of the protective sleeve (12); a rotation drive source is installed on one side of the bottom end of the conical housing (6); a main transmission shaft (9) is installed on the output end of the rotation drive source; the top end of the main transmission shaft (9) extends into the interior of the protective sleeve (12) and is installed with a bevel toothed disc bidirectional transmission structure (14) for driving the two worm gear transmission structures (15) to work synchronously and in reverse; and a PLC control panel (2) which is electrically connected to the rotation drive source and the input end of the electromagnetic heating graphite crucible (11) is installed on the outer wall of one side of the chassis (1).

2. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: A support ring (5) is fixed to one end of the inner part of the outer support sleeve (3), and the top end of the support ring (5) and the bottom end of the graphite end cover (4) are in contact with each other.

3. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: A lower flange edge (301) is fixed to one end of the surface of the outer support sleeve (3), and an upper flange edge (401) bolted to the lower flange edge (301) is provided on the outer edge of the top end of the graphite end cover (4).

4. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: A ceramic heat-insulating sleeve (302) for covering the outer support sleeve (3) is fixed to the top end of the chassis (1).

5. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: The electromagnetic heating graphite crucible (11) comprises a double-layer graphite crucible (1101) slidably mounted inside an inner steel bladder (10), and a first cavity (1102) and a second cavity (1103) arranged inside the double-layer graphite crucible (1101), wherein a steel sleeve (1104) and an electromagnetic coil (1105) are respectively mounted inside the first cavity (1102) and the second cavity (1103).

6. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: The rotation driving source comprises a stepping motor (7) mounted on one side of the bottom end of the conical housing (6), and a reducer (8) mounted on the output end of the stepping motor (7), and the main transmission shaft (9) is mounted on the output shaft of the reducer (8).

7. A thermal field structure for preparing silicon carbide crystals according to claim 1, characterized in that: The gear tooth plate lifting structure (13) comprises a vertical frame (1301) fixed to one side of the bottom of the conical housing (6), and a circular tooth frame (1302) slidably mounted on the inner wall of one side of the vertical frame (1301), the top of the circular tooth frame (1302) being fixedly connected to the bottom end of the electromagnetic heating graphite crucible (11), a secondary shaft (1303) being rotatably mounted on the outer wall of one side of the vertical frame (1301) close to the vertical center line of the conical housing (6), driving gears (1304) being fixed to both ends of the surface of the secondary shaft (1303), and the driving gear (1304) and the circular tooth frame (1302) being meshed with each other.

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