Multi-stock-column silicon carbide single crystal growth equipment and preparation process thereof

Abstract

The invention discloses multi-stock-column silicon carbide single crystal growth equipment which comprises a furnace body arranged on a furnace frame, a heat preservation layer, a crucible set and a resistance heater, and the resistance heater is arranged on the outer side of the outer circumferential face of the crucible set. And the crucible group comprises at least two sets of crucible suites which are circumferentially and uniformly distributed at the central position of the resistance heater, and a self-rotating mechanism for driving each set of crucible suites to rotate around a rotating shaft of the crucible suites. Therefore, the interiors of the plurality of crucibles can be heated by using the same heating device, and the growth of a plurality of silicon carbide single crystals is synchronously carried out, so that the production efficiency is improved, and the manufacturing cost is reduced; the whole equipment is more compact, the occupied space is smaller, and the required process gas and heating energy are less, so that more manufacturing cost is saved; and the self-rotating mechanism is arranged to drive each set of crucible suite to rotate around the self rotating shaft, so that each set of crucible suite is uniformly heated, and the growth quality of the silicon carbide single crystal is further ensured. The invention further discloses a preparation process of the equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide semiconductors, and in particular to a multi-pillar silicon carbide single crystal growth device and a preparation process thereof. Background Art

[0002] As an important third-generation wide bandgap semiconductor material, silicon carbide (SiC) single crystal has broad application prospects in power electronic devices used under extreme conditions such as high frequency, high power, radiation resistance, corrosion resistance, and high temperature resistance due to its advantages such as wide bandgap, high thermal conductivity, high critical breakdown electric field, and high electron saturation migration rate. The physical vapor transport method (PVT method) is a common method for growing silicon carbide single crystals. It mainly involves placing silicon carbide polycrystalline raw materials at the bottom of a cylindrical crucible body, and covering the crucible body with a crucible cover to form a closed space. A silicon carbide seed crystal is installed on the lower surface of the crucible cover. The system consisting of the crucible body and the crucible cover is heated by a heating body to sublimate the silicon carbide polycrystalline raw materials in the crucible body, and maintain a suitable axial (along the central axis direction of the cylindrical crucible body) temperature gradient between the silicon carbide polycrystalline raw materials and the silicon carbide seed crystals. The sublimated silicon carbide particles will be deposited and grown on the silicon carbide seed crystals, thereby obtaining silicon carbide single crystals.

[0003] The PVT growth device in the prior art usually has a crucible in a chamber, and can only grow one silicon carbide crystal in a certain period of time. However, the growth temperature of silicon carbide crystals is high, the growth speed is slow, and the device is expensive, which makes the growth cost of silicon carbide crystals much higher than the cost of silicon single crystals, and the application scope of silicon carbide crystals is greatly limited. Patent application KR1020230071771A Synchronous growth method and device of silicon carbide crystals in multiple crucibles discloses a silicon carbide single crystal growth device, including a cavity, an insulation layer arranged near the inner side wall of the cavity, and multiple heating bodies arranged in a grid inside the insulation layer. The internal space of the heating body constitutes multiple independent growth chambers, and each growth chamber is arranged with an independent growth assembly; the independent growth assembly includes a graphite crucible and a graphite crucible cover arranged on the top of the graphite crucible, and a seed crystal is provided at the bottom of the graphite crucible cover. The device is provided with multiple growth chambers capable of synchronous crystal growth inside the insulation layer, which improves the growth efficiency of silicon carbide crystals and reduces the growth cost of silicon carbide single crystals. However, the heating body in the device has a complex structure, and a heating body must be set between two adjacent growth chambers to accurately control the temperature of each area of ​​each crucible in the growth chamber to meet the process requirements of silicon carbide single crystal growth. This makes the entire equipment more complicated and occupies a larger base area, especially when producing large-sized silicon carbide single crystal workpieces.

[0004] In addition, since the growth of silicon carbide single crystals is particularly affected by temperature differences, the control requirements for the temperature of the crystal growth area are very strict. It is necessary to ensure that the temperature of the interface at the same height direction is consistent and controlled within a very small temperature difference range; especially for large-sized silicon carbide single crystals, the internal space of the crucible is large, resulting in the silicon carbide gas temperature near the center of the crucible being lower than the silicon carbide gas temperature near the crucible wall, causing the crystallization of each area on the seed crystal to be asynchronous, making it difficult to guarantee the quality of the silicon carbide single crystal.

[0005] In the prior art, a resistance heater is usually used to heat the crucible. Specifically, a single crucible resistance-heated silicon carbide single crystal growth device mainly includes an insulation layer arranged in a furnace body, a crucible located in the insulation layer, and a resistance heater arranged between the insulation layer and the crucible. The crucible is heated by the resistance heater, and the silicon carbide source powder inside the crucible is melted after being evenly heated, so that it sublimates and recrystallizes at the silicon carbide seed crystal located at the bottom of the crucible cover, thereby obtaining a silicon carbide single crystal. The resistance heater is usually arranged around the crucible, including the side, top and bottom surfaces, to ensure that the crucible is evenly heated. The temperature of each area in the crucible, especially the temperature of the crystal growth area, is accurately controlled by adjusting the position of the resistance heater. However, since the growth of silicon carbide single crystals is particularly sensitive to changes in the temperature field, and the central area in the confined space inside the crucible is farther away from the heating body than the area near the crucible wall, the temperature of the gas-phase silicon carbide in the central area is slightly lower than the temperature of the gas-phase silicon carbide near the crucible wall, which easily forms a radial temperature gradient and the crystallization rate of the gas-phase silicon carbide at the seed crystal is inconsistent, thereby affecting the quality of the silicon carbide single crystal, especially the growth of large-sized silicon carbide single crystals. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a multi-material column silicon carbide single crystal growth equipment with a simpler structure and capable of growing multiple single crystals simultaneously, in view of the problems of complex structure, large base area, poor product quality and low production efficiency existing in the multi-material column silicon carbide single crystal growth equipment in the prior art.

[0007] The technical solution to the technical problem of the present invention is: construct a multi-material column silicon carbide single crystal growth equipment, including a furnace body arranged on a furnace frame, an insulation layer attached to the inner wall of the furnace body, a crucible group and a resistance heater arranged in the insulation cavity of the insulation layer, the furnace body is arranged in a rotating body shape, and the resistance heater is arranged on the outside of the outer circumferential surface of the crucible group; the crucible group includes at least two sets of crucible sets evenly distributed circumferentially in the insulation cavity of the insulation layer, and also includes a spinning mechanism for driving each set of crucible sets to rotate around its own rotation axis.

[0008] Furthermore, the spinning mechanism includes a driving shaft driven by a self-rotating driving motor arranged outside the furnace body, a self-rotating shaft corresponding to each set of crucible sets, and a gear set arranged between the driving shaft and the self-rotating shaft; through the gear set, one motor can be used to drive all the self-rotating shafts to rotate synchronously.

[0009] Furthermore, the crucible group also includes a crucible lifting device, which includes a lifting slide plate slidably arranged on the furnace frame, and a first screw rod driven by a lifting drive motor, the lifting slide plate is provided with a threaded hole matching the first screw rod, the end of the rotating shaft is rotatably arranged on the top of the lifting slide plate, the rotating drive motor and the gear group are arranged on the lifting slide plate and rise and fall together with the lifting slide plate; the lifting drive motor is controlled to drive the first screw rod to rotate, thereby driving the lifting slide plate to rise and fall, thereby driving all the rotating shafts to rise and fall.

[0010] Furthermore, the crucible lifting device also includes a slide plate guide rod vertically arranged on the furnace frame, and a guide through hole matching with the slide plate guide rod is opened on the lifting slide plate, so that the lifting slide plate is smoother during the lifting process.

[0011] Furthermore, each crucible set in the at least two crucible sets includes an upper crucible and a lower crucible, a gas delivery pipe is provided between the upper crucible and the lower crucible, the upper crucible includes an upper crucible body and an upper crucible cover, the lower crucible includes a lower crucible body and a lower crucible cover, and the gas delivery pipe is provided between the upper crucible body and the lower crucible cover; the gas delivery pipe makes the area between the seed crystal and the silicon carbide polycrystalline liquid level in the enclosed space in the crucible smaller, the gas phase silicon carbide here is less, and the temperature gradient is not easily generated, thereby improving the radial uniformity of the silicon carbide single crystal, thereby further improving the quality of the silicon carbide single crystal.

[0012] Furthermore, the resistance heater includes an upper heating body arranged around the crucible group and corresponding to the position of the upper crucible in the crucible suite, a lower heating body arranged around the crucible group and corresponding to the position of the lower crucible in the crucible suite, and an intermediate heating body arranged around the gas phase delivery tube; the intermediate heating body is arranged in a flat plate shape, and a through hole matching the gas phase delivery tube of each crucible suite is opened on the flat plate-shaped intermediate heating body; the lower heating body can maintain the temperature required for sublimation of silicon carbide polycrystalline raw material in the lower crucible in each set of crucible suites, the upper heating body can maintain the temperature required for condensation of the upper crucible in each set of crucible suites, and the intermediate heating body can maintain the temperature of gas-phase silicon carbide in the gas phase delivery tube to reduce the influence of temperature difference on crystal growth quality; at the same time, the provision of the through hole can avoid the interference of the intermediate heating body with the rotation of each set of crucible suites through the spinning mechanism.

[0013] Furthermore, a crystal heat exchange device is provided directly above the upper crucible cover in each set of the crucible kit, and each of the crystal heat exchange devices includes a heat exchange plate matching the corresponding top surface of the upper crucible cover, a second lifting guide rod passing through the insulation layer and the furnace body and connected to the heat exchange plate, a second drive motor arranged on the top of the furnace body, a second screw rod driven by the second drive motor, and a second slider sleeved on the second screw rod, the second slider is fixed to the top end of the second lifting guide rod, and the second slider is threadedly connected to the second screw rod; the second drive motor drives the second screw rod to rotate, driving the second slider to move up and down along the second screw rod, thereby driving the corresponding second lifting guide rod to slide up and down, and the second lifting guide rod drives the heat exchange plate to rise and fall, so that the heat exchange plate contacts or separates from the top surface of the upper crucible cover, timely reduces the temperature of the seed crystal fixed on the ground of the upper crucible cover, controls the seed crystal temperature to meet the process requirements, and further ensures the quality of the silicon carbide single crystal.

[0014] Furthermore, the crystal heat exchange device also includes a temperature measuring device capable of detecting the temperature of the corresponding upper crucible cover, the temperature measuring device including an infrared thermometer with a detection head arranged at the top of the second lifting guide rod, and a temperature measuring channel arranged in the second lifting guide rod, one end of the temperature measuring channel passes through the heat exchange plate and faces the top surface of the upper crucible cover, and the other end matches the infrared thermometer; the temperature of the top surface of the upper crucible cover detected by the detection head of the infrared thermometer through the temperature measuring channel in time can determine the temperature of the seed crystal.

[0015] Furthermore, it also includes a control system, which is electrically connected to each of the second drive motors and each of the infrared thermometers. The control system controls the corresponding second drive motor to drive the second screw to rotate according to the temperature of the corresponding upper crucible cover top surface detected by the corresponding infrared thermometer, thereby driving the corresponding heat exchange plate to rise and fall; the control system can automatically control the heat exchange plate to contact or separate from the upper crucible cover top surface according to the temperature detected by the infrared thermometer, thereby realizing automatic adjustment of the seed crystal temperature.

[0016] Another technical problem to be solved by the present invention is to provide a preparation process for a multi-pillar silicon carbide single crystal growth device in order to solve the problems of poor product quality and low production efficiency in the prior art multi-pillar silicon carbide single crystal preparation process.

[0017] The technical solution of the technical problem of the present invention is: construct a preparation process of a multi-pillar silicon carbide single crystal growth device, comprising the following steps: Constructing the multi-pillar silicon carbide single crystal growth apparatus as described above; A seed crystal is arranged at the bottom of the upper crucible cover in each set of crucible sets; a silicon carbide polycrystalline raw material is placed in the lower crucible in each set of crucible sets to complete the furnace loading; The whole equipment is evacuated to make the vacuum degree in the furnace reach below 0.1pa; The driving spin mechanism drives each set of crucible sets to rotate; The temperature of the furnace chamber is raised in stages and the furnace vacuum is maintained below 0.1 Pa; The temperature of the chamber in the furnace body is maintained at 2000-2500°C by controlling the operation of the resistance heater, and at the same time, the vacuum is stopped and the chamber in the furnace body is filled with inert gas, and the pressure is increased to 10-60kPa, and the pressure is maintained for 3-5 hours; The temperature of the chamber in the furnace body is maintained at 2000-2500°C by controlling the operation of the resistance heater, and the pressure is gradually reduced to 100-3000Pa within 3-10 hours; According to the size requirements of the silicon carbide single crystal growth, the temperature and pressure of the chamber in the furnace body are maintained constant for 50-300 hours; at the same time, the position of the crucible is adjusted according to the position of the detected crystal growth interface; After the growth of silicon carbide single crystal is completed, the pressure is released and the temperature is lowered.

[0018] The implementation of the multi-pillar silicon carbide single crystal growth equipment and the preparation process thereof described in the present invention has the following beneficial effects: by arranging at least two sets of crucible sets in the internal chamber of the insulation layer, the same set of heating devices can be used to heat multiple crucibles and simultaneously grow multiple silicon carbide single crystals, thereby improving production efficiency and reducing manufacturing costs; by arranging at least two sets of crucible sets evenly distributed circumferentially in the internal chamber of the insulation layer, the overall equipment is more compact, occupies less space, requires less process gas and heating energy, and thus saves more manufacturing costs; by arranging a spin mechanism to drive each set of crucible sets to rotate around its own rotation axis, different areas of each set of crucible sets can be evenly heated by the resistance heater located on the outer circumferential surface of the crucible group, further ensuring the quality of silicon carbide single crystal growth.

[0019] Furthermore, by setting a crucible including an upper crucible and a lower crucible, and arranging a gas phase delivery pipe between the upper and lower crucibles, the space of the area between the seed crystal and the silicon carbide polycrystalline liquid surface in the closed space in the crucible becomes smaller, the gas phase silicon carbide here is less, and it is not easy to generate a temperature gradient; at the same time, the gas phase silicon carbide in each area with a temperature gradient in the lower crucible is fully mixed in the gas phase delivery pipe to form a gas phase silicon carbide with a uniform temperature; thereby ensuring that the crystallization speed of the gas phase silicon carbide at the seed crystal is consistent, improving the radial uniformity of the silicon carbide single crystal, and thus ensuring the quality of the silicon carbide single crystal. In addition, the present invention further enhances the equipment's fine control of the temperature of each area in the crucible by arranging an intermediate heating body around the gas phase delivery pipe, arranging a crucible lifting device at the bottom of the lower crucible body, and arranging a crystal heat exchange device just above the upper crucible cover, thereby avoiding the influence of the temperature difference in each area on the growth quality of the silicon carbide single crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure shows the overall structure schematic diagram of a preferred embodiment of the multi-pillar silicon carbide single crystal growth device of the present invention; Figure 2 Shown Figure 1 An enlarged schematic diagram of part I; Figure 3 Shown Figure 1 An enlarged schematic diagram of Part II; Figure 4 Shown Figure 1 AA section view. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] It should also be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0024] like Figure 1 , 2As shown in Figures 3 and 4, in a preferred embodiment of the multi-pillar silicon carbide single crystal growth equipment of the present invention, it mainly includes a furnace frame 13, a furnace body 10, a heat preservation layer 20, a crucible group 30, and a resistance heater 90. Among them, the furnace body 10 is preferably set to a rotating body shape, such as a cylindrical shape; the furnace body 10 can be set to include an upper furnace cover 11 and / or a lower furnace cover 12 as needed, and the furnace body 10 can be quickly opened after the upper furnace cover 11 and / or the lower furnace cover 12 are removed, so that the silicon carbide polycrystalline raw material 3 can be placed in the corresponding crucible before preparing the silicon carbide single crystal, and the silicon carbide seed crystal 1 can be installed in the corresponding crucible. At the same time, the upper furnace cover 11 and / or the lower furnace cover 12 are reliably sealed on the furnace body 10 to ensure that the space inside the furnace body 10 is airtight during the preparation process to prevent the silicon carbide in the furnace body 10 from being contaminated. The furnace frame 13 is used to support the entire furnace body 10. The insulation layer 20 is evenly arranged inside the furnace body 10, and specifically, the insulation layer 20 can be attached to the inner wall of the furnace body 10, so as to form an insulation cavity 21 inside the furnace body 10. The crucible group 30 and the resistance heater 90 are arranged in the insulation cavity 21, wherein the resistance heater 90 is arranged outside the outer circumference of the crucible group 30, that is, the crucible group 30 is arranged at the center of the insulation cavity 21, the resistance heater 90 is arranged between the crucible group 30 and the insulation layer 20, and the resistance heater 90 is wound around the inner wall of the insulation layer 20.

[0025] like Figure 1 , 4 As shown, in this preferred embodiment, the crucible group 30 includes at least two sets of crucible sets 40 arranged in the heat-insulating cavity 21, and preferably the crucible group 30 includes four sets of crucible sets 40; the four sets of crucible sets 40 are evenly distributed in the heat-insulating cavity 21, and are respectively located in the first station 31, the second station 32, the third station 33 and the fourth station 34 in the heat-insulating cavity 21. Among them, it is preferred to set each set of crucible sets 40 to include an upper crucible 41 and a lower crucible 42, and a gas phase delivery pipe 43 is connected between the upper crucible 41 and the lower crucible 42. Specifically, the upper crucible 41 can be provided to include an upper crucible cover 41a and an upper crucible body 41b, and the upper crucible cover 41a is sealed and arranged at the upper end opening of the upper crucible body 41b; the lower crucible 42 is provided to include a lower crucible cover 42a and a lower crucible body 42b, and the lower crucible cover 42a is sealed and arranged at the upper end opening of the lower crucible body 42b. The gas phase delivery pipe 43 is connected between the bottom of the upper crucible body 41b and the lower crucible cover 42a. The silicon carbide polycrystalline raw material 3 is placed in the lower crucible body 42b of the lower crucible, and the silicon carbide seed crystal 1 is fixedly arranged on the bottom surface of the upper crucible cover 41a. In this preferred embodiment, the upper crucible 41, the lower crucible 42 and the gas phase delivery pipe 43 are preferably made of high-purity graphite material with surface coating treatment to ensure that each area in the crucible can be evenly heated when heated.

[0026] like Figure 1 , 2As shown, in this preferred embodiment, the crucible set 30 also includes a spin mechanism 50 that drives each set of crucible sets 40 to rotate around its own rotation axis. The spin mechanism 50 includes a self-rotation drive motor 54, a drive shaft 51, and a self-rotation shaft 52 corresponding to each set of crucible sets 40, and a gear set 53 connected and arranged between the drive shaft 51 and the self-rotation shaft 52. Specifically, the self-rotation drive motor 54 can be a servo motor or a variable frequency motor, etc.; the drive shaft 51 is arranged below the furnace body 10 and driven to rotate by the self-rotation drive motor 54, and the drive shaft 51 is arranged coaxially with the central axis of the furnace body 10. One end of the self-rotation shaft 52 is fixed to the bottom of the lower crucible body 42b in the corresponding crucible set 40 to drive the corresponding crucible set 40 to rotate; the other end of the self-rotation shaft 52 passes through the insulation layer 20 and the furnace body 10 and extends to the vicinity of the drive shaft 51, and the gear set 53 includes a gear sleeved on the end of the self-rotation shaft 52 and a gear sleeved on the end of the drive shaft 51, and the two are meshed to form a gear pair. When the self-rotating driving motor 54 drives the driving shaft 51 to rotate, each self-rotating shaft 52 is driven to rotate through the gear side effect of the gear set 53, thereby driving the corresponding crucible set 40 to rotate around its own rotation axis, so that the crucibles of the crucible set are evenly heated and the temperature difference is reduced.

[0027] In this preferred embodiment, the crucible group is preferably provided with a crucible lifting device 60, which is used to drive the crucible to rise and fall, so as to adjust the horizontal position of the crucible in the heat preservation cavity 21, and control the upper crystal growth interface of the seed crystal in the upper crucible 41 to always be located in the temperature region required by the process. The crucible lifting device 60 is preferably provided with a lifting slide 61, a lifting drive motor 62 and a first screw rod 63. The lifting slide 61 is slidably arranged on the furnace frame 13 and is located below the furnace body 10; the first screw rod 63 is vertically rotatably arranged on the furnace frame 13, and the lifting drive motor 62 is arranged on the furnace frame 13 at the end of the first screw rod 63, and the lifting drive motor 62 can drive the first screw rod 63 to rotate, and the lifting drive motor 62 can be a servo motor or a variable frequency motor. It is preferred that a threaded hole 64 matching with the first screw rod 63 is provided on the lifting slide 61, and when the lifting drive motor 62 drives the first screw rod 63 to rotate forward and reverse, under the action of the threaded hole 64 and the first screw rod 63, the lifting slide 61 can rise or fall below the furnace body 10. One end of the self-rotating shaft 52 in the above-mentioned self-rotating mechanism is rotatably arranged on the top of the lifting slide 61, and the other end extends to the bottom of the lower crucible body 42b of the corresponding crucible set; the self-rotating driving motor 54 and the gear set 53 are arranged on the lifting slide 61 and can be lifted and lowered together with the lifting slide 61. By controlling the lifting driving motor 62 to drive the first screw rod 63 to rotate, the lifting slide 61 is driven to lift and lower, thereby driving all the self-rotating shafts 52 to lift and lower. It is best to set the crucible lifting device 60 to also include a slide guide rod 65, the slide guide rod 65 is vertically arranged on the furnace frame 13, and the lifting slide 61 is provided with a guide through hole 66 that matches the slide guide rod 65. When the first screw rod 63 rotates in the threaded hole 64 to drive the lifting slide 61 to slide up and down, the slide guide rod 65 slides relative to the lifting slide 61 along the guide through hole 66, so that the entire lifting slide 61 can be lifted and lowered more smoothly. According to needs, multiple slide guide rods 65 can be arranged on the furnace frame 13, and correspondingly, a corresponding number of guide through holes 66 are opened on the lifting slide 61.

[0028] In this preferred embodiment, a control system (not shown in the figure) is also included, which is electrically connected to the self-rotation drive motor 54, and can automatically control the start and stop of the self-rotation drive motor 54 during the operation of the furnace body 10, thereby controlling the self-rotation of the crucible set 40. The control system can also be set to be electrically connected to the lifting drive motor 62, and the growth speed of silicon carbide can be controlled according to the preset speed by adjusting the process conditions, so as to determine the position information of the silicon carbide growth interface in the upper crucible 4131; the control system can automatically control the lifting drive motor 62 to drive the self-rotation shaft 52 to rise and fall according to the position change of the growth interface, thereby driving each set of crucible sets 40 in the crucible group 30 to rise and fall, so as to automatically control the growth interface of the silicon carbide seed crystal 1 to always be in the temperature area required by the process, and further ensure the growth quality of the silicon carbide single crystal 2.

[0029] like Figure 1 ,3 As shown, in this preferred embodiment, when the lower crucible 42 of the crucible set is heated by the resistance heater 90, the silicon carbide polycrystalline raw material 3 in the lower crucible 42 is sublimated into gaseous silicon carbide, and the gaseous silicon carbide enters the upper crucible body 41b through the gas phase delivery pipe 43 and evenly fills the space in the upper crucible 41, and the gaseous silicon carbide gradually cools and recrystallizes at the silicon carbide seed crystal 1 to form a silicon carbide single crystal 2. When the resistance heater 90 heats the crucible, the gaseous silicon carbide generated in the lower crucible 42 is gathered in the gas phase delivery pipe 43, and the gaseous silicon carbide in each area with a temperature gradient in the lower crucible 42 is fully mixed in the gas phase delivery pipe 43 to form gaseous silicon carbide with a uniform temperature. It is best to set the lower crucible cover 42a to a trumpet shape with a small top and a large bottom, so that the gaseous silicon carbide in each area of ​​the lower crucible 42 can be quickly gathered in the gas phase delivery pipe 43. It is best to set the bottom of the upper crucible body 41b to be a trumpet shape with a larger top and a smaller bottom, so that the gas phase silicon carbide with uniform temperature delivered by the gas phase delivery pipe 43 can quickly diffuse into the internal space of the upper crucible 41 and grow evenly on the silicon carbide seed crystal 1.

[0030] In this preferred embodiment, the resistive heater 90 preferably includes an upper heating body 91, a lower heating body 92 and an intermediate heating body 93. The lower heating body 92 is preferably arranged around the lower crucible 42 to heat the lower crucible body 42b so that the silicon carbide polycrystalline raw material 3 in the lower crucible 42 can be sublimated into gas-phase silicon carbide. The intermediate heating body 93 is preferably arranged around the gas-phase delivery pipe 43 so as to control the temperature of the gas-phase silicon carbide in the gas-phase delivery pipe 43 to meet the process requirements. The upper heating body 91 is preferably arranged around the upper crucible 41 to heat the upper crucible 41. After the upper crucible 41 is heated, it can evenly radiate heat to each area in the upper crucible body 41b to maintain the temperature of the gas-phase silicon carbide in the upper crucible 41, control the temperature of the crystallization interface at the silicon carbide seed crystal 1, and ensure the growth quality of the silicon carbide single crystal 2.

[0031] A bottom heating body 94 may be provided below the crucible assembly 30 as required, so that the lower crucible body 42b is heated evenly, further reducing the temperature difference of gas phase silicon carbide in each region of the lower crucible 42. The upper heating body 91, the lower heating body 92, the middle heating body 93, and the bottom heating body 94 are all individually controlled by a control system (not shown in the figure) so that each region in the crucible can be heated as required so that the temperature of each region meets the process requirements.

[0032] like Figure 1 , 2As shown, in this preferred embodiment, a crystal heat exchange device 70 is preferably arranged just above the upper crucible cover 41a in each set of crucible sets, so as to timely adjust the temperature of the upper crucible cover 41a, that is, adjust the temperature of the bottom plate of the silicon carbide seed crystal 1, so that the temperature of the silicon carbide seed crystal 1 meets the process requirements. Specifically, the crystal heat exchange device 70 is preferably arranged to include a heat exchange plate 71, a lifting guide rod 72, a heat exchange drive motor 73, a second screw rod 74, and a slider 75. Among them, the heat exchange plate 71 is arranged in the insulation layer 20 and is located just above the upper crucible cover 41a. The bottom surface of the heat exchange plate 71 matches the top surface of the upper crucible cover 41a, that is, the shape of its bottom surface is adapted to the shape of the top surface of the upper crucible cover, so that when the heat exchange plate 71 contacts the upper crucible cover 41a, the bottom surface of the heat exchange plate 71 is completely fitted with the top surface of the upper crucible cover 41a, so as to ensure that the heat of the upper crucible cover 41a can be quickly transferred to the heat exchange plate 71. The lifting guide rod 72 passes through the insulation layer 20 and the upper furnace cover 11, and can slide up and down relative to the insulation layer 20 and the furnace body 10. Its bottom end is fixedly connected to the heat exchange plate 71 and its top end is located outside the furnace body 10. The heat exchange drive motor 73 is arranged on the top of the furnace body 10, and can be a servo motor or a variable frequency motor. The second screw rod 74 is rotatably arranged on the top of the upper furnace cover 11 and driven to rotate by the heat exchange drive motor 73. Specifically, the heat exchange drive motor 73 can be arranged at the end of the second screw rod 74. The slider 75 is sleeved on the second screw rod 74 and fixed on the top of the lifting guide rod 72. Specifically, a threaded hole 75a matching the second screw rod 74 can be arranged at the center of the slider 75, and the threaded hole 75a of the slider is sleeved on the second screw rod 74, and the slider 75 is fixedly arranged on the side of the lifting guide rod 72. When the heat exchange driving motor 73 drives the second screw rod 74 to rotate, the slider 75 can be lifted and lowered along the second screw rod 74, thereby driving the lifting guide rod 72 to slide up and down, so that the heat exchange plate 71 located at the bottom end of the lifting guide rod can also move up and down.

[0033] Preferably, each crystal heat exchange device 70 further includes a temperature measuring device 80, which can detect the temperature of the upper crucible cover 41a in real time. The temperature measuring device 80 includes an infrared thermometer 81 with a detection head 82 and a temperature measuring channel 83 arranged in the lifting guide rod 72. Specifically, it is best to set the lifting guide rod 72 to be hollow, and the hollow part is the temperature measuring channel 83. Since the heat exchange plate 71 is fixed to the bottom end of the lifting guide rod 72, it is best to set a through hole matching the temperature measuring channel 83 on the heat exchange plate 71, so that the temperature measuring channel 83 can be directly facing the top surface of the upper crucible cover 41a after passing through the heat exchange plate 71. The infrared thermometer 81 is set at the top of the lifting guide rod 72, and it is ensured that the detection head 82 can just pass through the temperature measuring channel 83 to irradiate the top surface of the upper crucible cover 41a. In this way, the detection head 82 of the infrared thermometer can directly detect the real-time temperature of the top surface of the upper crucible cover 41a through the temperature measuring channel 83.

[0034] Similarly, a control system may be provided to be electrically connected to the heat exchange drive motor 73 and the infrared thermometer 81 of each crucible set, and the control system may be provided to automatically control the corresponding heat exchange drive motor 73 to drive the corresponding lifting guide rod 72 to slide up and down according to the temperature of the top surface of the upper crucible cover 41a detected by the infrared thermometer 81, thereby driving the corresponding heat exchange plate 71 to rise and fall, so that the heat exchange plate 71 is in close contact with or separated from the corresponding upper crucible cover 41a, and the heat of the upper crucible cover 41a is quickly transferred to the heat exchange plate 71 to adjust the temperature of the silicon carbide seed crystal 1 located on the bottom surface of the upper crucible cover to ensure that it meets the process requirements. Specifically, when the temperature of the top surface of the upper crucible cover 41a detected by the infrared thermometer 81 is higher than a preset value, the control system automatically controls the heat exchange plate 71 to descend to a preset position, so that the heat exchange plate 71 is in close contact with the upper crucible cover 41a; when the temperature of the top surface of the upper crucible cover 41a detected by the infrared thermometer 81 is lower than a preset value, the control system automatically controls the heat exchange plate 71 to rise to a preset position, so that the heat exchange plate 71 is separated from the upper crucible cover 41a.

[0035] In this preferred embodiment, the insulation layer 20 is preferably provided with an upper movable insulation block 22 corresponding to each set of crucible sets, and the upper movable insulation block 22 is fixed around the corresponding lifting guide rod 72 and sleeved on the top of the corresponding heat exchange plate 71, so that the upper movable insulation block 22 is lifted and lowered together with the heat exchange plate 71. Specifically, an upper opening 23 matching the outer contour of the upper movable insulation block 22 can be provided at the corresponding position of the insulation layer 20, and when the upper movable insulation block 22 is lifted and lowered together with the heat exchange plate 71, the upper movable insulation block 22 is just embedded in the upper opening 23. The upper movable insulation block can be lifted and lowered together with the heat exchange plate 71, which not only ensures the thermal sealing of the internal space of the insulation layer 20, but also does not affect the lifting and lowering movement of the heat exchange plate 71.

[0036] In the above embodiment, a process gas path system (not shown in the figure) may also be included to control the vacuum degree in the furnace body 10 and to fill the furnace body 10 with process gas; a water cooling system (not shown in the figure) may also be provided as needed to accelerate the cooling speed of the furnace body 10 after the preparation of the silicon carbide single crystal 2 is completed.

[0037] In a preferred embodiment of the preparation process of the multi-pillar silicon carbide single crystal growth device of the present invention, the following steps are included: S10. A silicon carbide single crystal growth apparatus constructed as described above; S20. The silicon carbide seed crystal is fixed to the bottom of the upper crucible cover; the silicon carbide polycrystalline raw material is placed in the lower crucible to complete the furnace loading process; S30. The equipment is vacuumed so that the vacuum degree in the furnace reaches below 0.1 Pa, completing the vacuuming process; S40. The driving spin mechanism drives each set of crucible kits to rotate; S50. The temperature of the furnace chamber is raised in stages and the vacuum of the furnace is maintained below 0.1 Pa to complete the heating process; S60. Maintain the temperature of the furnace chamber at 2000-2500°C by controlling the resistance heater, stop vacuuming and fill the furnace chamber with inert gas, and increase the pressure to 10-60kPa, maintain the pressure for 3-5 hours, and complete the gas filling and pressurization process; S70. Maintaining the temperature of the furnace chamber at 2000-2500°C by controlling the resistance heater, while gradually reducing the pressure, reducing the furnace chamber pressure to 100-3000Pa within 3-10 hours, completing the depressurization process; S80. According to the size requirements of silicon carbide single crystal growth, the temperature and pressure of the furnace chamber are maintained constant for 50-300 hours; while adjusting the position of the crucible according to the position of the detected crystal growth interface to complete the crystal growth process; S90. After the growth of the silicon carbide single crystal is completed, the pressure is released, the temperature is lowered, and the finished product is taken out to complete the furnace unloading process.

[0038] In step S10, the equipment is preferably provided to include a vacuum system. At the same time, in step S30, the vacuum system is controlled by the control system to vacuum the furnace body so that the vacuum degree in the furnace body is below 0.1 Pa. Specifically, a vacuum gauge can be provided on the furnace body to monitor the vacuum degree in the furnace body in real time.

[0039] In step S20, the upper furnace cover may be opened, and then the upper movable insulation block of the insulation layer may be opened to load each set of crucible sets into the furnace.

[0040] In step S40, the control system controls the self-rotating driving motor to drive the driving shaft to rotate, and drives the following self-rotating shafts to rotate through the gear set; the self-rotating shaft drives the corresponding crucible set to rotate around its own rotation axis, so that the crucible is evenly heated.

[0041] In step S50, the heating stage can be divided into two stages: S41. Control the resistance heater to raise the temperature of the furnace chamber to 1000-1200°C within 2 hours, maintain the vacuum degree in the furnace below 0.1 Pa, and keep the temperature constant for 5-10 hours; S43. Control the resistance heater to raise the temperature of the chamber in the furnace to 2000-2500°C within 5 hours, maintain the vacuum degree in the furnace below 0.1 Pa, and keep the temperature constant for 5-10 hours.

[0042] By increasing the temperature in stages and keeping the temperature constant for a certain period of time in each stage, the crucible can be heated evenly, ensuring that the temperature of each part of the crucible body is consistent, so that the temperature of each area in the crucible is basically consistent. Specifically, a thermometer can be set in different areas of the insulation cavity, and the control system controls the resistance heater of the corresponding area according to the temperature of each area, such as the upper heating body, the middle heating body, the lower heating body, the bottom heating body, etc., to ensure that the temperature difference of each area does not exceed the preset range.

[0043] In step S80, the control system can be specifically configured to automatically control the lifting drive motor according to a preset program to drive all the crucible kits to lift and lower in the insulation cavity through the lifting slide, to ensure that the crystal growth interface is always located in the temperature area required by the process; at the same time, the control system can also be configured to automatically control the corresponding heat exchange drive motor to drive the corresponding heat exchange plate to lift and lower according to the temperature of the top surface of the upper crucible cover detected by the infrared thermometer, so as to timely adjust the temperature of the silicon carbide seed crystal located on the bottom surface of the upper crucible cover.

[0044] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work, any modifications, equivalent substitutions, improvements, etc. made should be included in the protection scope of the present invention.

Claims

1. A multi-pillar silicon carbide single crystal growth device, comprising a furnace body arranged on a furnace frame, a heat preservation layer attached to the inner wall of the furnace body, a crucible group and a resistance heater arranged in a heat preservation cavity of the heat preservation layer, characterized in that: The furnace body is arranged in a rotating body shape, and the resistance heater is arranged outside the outer circumferential surface of the crucible group; the crucible group includes at least two sets of crucible sets evenly distributed around the circumference of the resistance heater, and also includes a spinning mechanism that drives each set of crucible sets to rotate around its own rotation axis.

2. The multi-pillar silicon carbide single crystal growth equipment according to claim 1, characterized in that: The spin mechanism comprises a drive shaft arranged outside the furnace body and driven by a self-rotation drive motor, a self-rotation shaft arranged corresponding to each set of crucible sets, and a gear set arranged between the drive shaft and the self-rotation shaft.

3. The multi-pillar silicon carbide single crystal growth equipment according to claim 2, characterized in that: The crucible group also includes a crucible lifting device, which includes a lifting slide plate slidably arranged on the furnace frame and a first screw rod driven by a lifting drive motor. The lifting slide plate is provided with a threaded hole matched with the first screw rod. The end of the rotation shaft is rotatably arranged on the top of the lifting slide plate. The rotation drive motor and the gear group are arranged on the lifting slide plate and rise and fall together with the lifting slide plate.

4. The multi-pillar silicon carbide single crystal growth equipment according to claim 3, characterized in that: The crucible lifting device also includes a slide plate guide rod vertically arranged on the furnace frame, and a guide through hole matched with the slide plate guide rod is opened on the lifting slide plate.

5. The multi-pillar silicon carbide single crystal growth equipment according to any one of claims 1 to 4, characterized in that: Each crucible set of the at least two crucible sets includes an upper crucible and a lower crucible, a gas phase delivery pipe is provided between the upper crucible and the lower crucible, the upper crucible includes an upper crucible body and an upper crucible cover, the lower crucible includes a lower crucible body and a lower crucible cover, and the gas phase delivery pipe is provided between the upper crucible body and the lower crucible cover.

6. The multi-pillar silicon carbide single crystal growth equipment according to claim 5, characterized in that: The resistance heater includes an upper heating body arranged around the crucible group and corresponding to the position of the upper crucible in the crucible kit, a lower heating body arranged around the crucible group and corresponding to the position of the lower crucible in the crucible kit, and an intermediate heating body arranged around the gas phase delivery pipe; the intermediate heating body is arranged in a flat plate shape, and a through hole matching the gas phase delivery pipe of each crucible kit is opened on the flat plate-shaped intermediate heating body.

7. The multi-pillar silicon carbide single crystal growth equipment according to claim 6, characterized in that: A crystal heat exchange device is provided directly above the upper crucible cover in each set of the crucible kit, and each of the crystal heat exchange devices includes a heat exchange plate matching the top surface of the corresponding upper crucible cover, a second lifting guide rod passing through the insulation layer and the furnace body and connected to the heat exchange plate, a second drive motor arranged on the top of the furnace body, a second screw rod driven by the second drive motor, and a second slider sleeved on the second screw rod, the second slider is fixed to the top end of the second lifting guide rod, and the second slider is threadedly connected to the second screw rod.

8. The multi-pillar silicon carbide single crystal growth equipment according to claim 7, characterized in that: The crystal heat exchange device also includes a temperature measuring device capable of detecting the temperature of the corresponding upper crucible cover, the temperature measuring device includes an infrared thermometer with a detection head arranged on the top of the second lifting guide rod, and a temperature measuring channel arranged in the second lifting guide rod, one end of the temperature measuring channel passes through the heat exchange plate and faces the top surface of the upper crucible cover, and the other end matches the infrared thermometer.

9. The multi-pillar silicon carbide single crystal growth equipment according to claim 8, characterized in that: It also includes a control system, which is electrically connected to each of the second drive motors and each of the infrared thermometers. The control system controls the corresponding second drive motor to drive the second screw to rotate according to the temperature of the top surface of the corresponding upper crucible cover detected by the corresponding infrared thermometer, thereby driving the corresponding heat exchange plate to rise and fall.

10. A preparation process for a multi-pillar silicon carbide single crystal growth device, characterized in that: The following steps are involved: S10. Constructing a multi-pillar silicon carbide single crystal growth apparatus according to any one of claims 1 to 9; S20. A seed crystal is set at the bottom of the upper crucible cover in each crucible package; polycrystalline silicon carbide raw material is placed in the lower crucible of each crucible package to complete the furnace; S30. The entire device is evacuated to make the vacuum degree in the furnace reach below 0.1 Pa; S40. The driving spin mechanism drives each set of crucible kits to rotate; S50. The temperature of the furnace chamber is raised in stages and the vacuum of the furnace is maintained below 0.1 Pa; S60. Maintain the temperature of the furnace chamber at 2000-2500°C by controlling the resistance heater, stop evacuating the furnace chamber, fill it with inert gas, and increase the pressure to 10-60 kPa for 3-5 hours; S70. Maintaining the temperature of the furnace chamber at 2000-2500°C by controlling the resistance heater, while gradually reducing the pressure to 100-3000Pa within 3-10 hours; S80. According to the size requirements of silicon carbide single crystal growth, maintaining the temperature and pressure of the furnace chamber unchanged for 50-300 hours; while adjusting the position of the crucible according to the position of the detected crystal growth interface; S90. After the growth of the silicon carbide single crystal is completed, the pressure is released and the temperature is lowered.

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