CN220300918U

CN220300918U - Single crystal type SiC crystal growing device

Info

Publication number: CN220300918U
Application number: CN202321589645.4U
Authority: CN
Inventors: 王朝人; 王文祥
Original assignee: Hainan Qicang Investment Co ltd
Current assignee: Hainan Qicang Investment Co ltd
Priority date: 2023-06-21
Filing date: 2023-06-21
Publication date: 2024-01-05
Anticipated expiration: 2033-06-21

Abstract

The utility model provides a single crystal type SiC crystal growing device, which comprises: a furnace body and a heating device; a graphite crucible is arranged in the furnace body, and the outer surface of the graphite crucible is coated with a heat insulation material; the heating device comprises a coil, the position of the coil can move along the axis direction of the furnace body, and the current and/or voltage of the coil can be controlled in a layered manner; under the operating condition, the highest point of the temperature in the furnace body is at the position from top to bottom about 60% of the axial direction of the graphite crucible, the upward temperature gradient of the position is in a first threshold range, the downward temperature gradient of the position is in a second threshold range, the lower limit value of the first threshold range is larger than the upper limit value of the second threshold range, the device can reduce the heat dissipation effect of the graphite crucible, improve the heat insulation performance of the graphite crucible, ensure the stable thermal field environment inside the graphite crucible, effectively improve the sealing performance, and ensure that the device can still ensure the quality of crystals in the process of producing crystals with high efficiency.

Description

Single crystal type SiC crystal growing device

Technical Field

The utility model relates to the technical field of crystal growth, in particular to a monocrystal type SiC crystal growth device.

Background

Currently, siC crystal growth devices (see patent documents such as US7192482B2 and CN 2685333Y) cannot accurately control various growth parameters, especially cannot accurately control growth temperature gradient parameters, so that the product has problems of polymorphic inclusion and slow growth speed, meanwhile, silicon carbide crystals form thermal stress due to sliding defects or base surface dislocation in the crystal growth process, so that the crystals of the produced crystal columns are unqualified, large-size crystal columns cannot be produced, and further cutting into usable wafers is impossible. In the subsequent slicing process, the reverse leakage current is increased, so that the wafer yield cannot be improved. Therefore, it is needed to solve at least one of the problems of impurity crystals, slow growth speed and various thermal stresses in the crystal growth by overcoming the structural design defects of the equipment in the prior art, improving the operability of the SiC crystal growth device, especially the control problem of the temperature field and the temperature gradient.

Disclosure of Invention

In order to overcome at least one of the problems in the related art, the present utility model provides a single crystal type SiC growing apparatus.

The single crystal type SiC crystal growing device comprises:

a furnace body and a heating device;

a graphite crucible is arranged in the furnace body, and the outer surface of the graphite crucible is coated with a heat insulation material;

the heating device comprises a coil, the position of the coil can move along the axis direction of the furnace body, and the current and/or voltage of the coil can be controlled in a layered manner;

the highest point of the working temperature in the furnace body is at a position from top to bottom about 60% in the axial direction of the graphite crucible, the upward temperature gradient of the position is in a first threshold range, the downward temperature gradient of the position is in a second threshold range, and the lower limit value of the first threshold range is larger than the upper limit value of the second threshold range.

In an alternative embodiment, the first threshold range is 1.5-2.0 ℃/mm and the second threshold range is 0.8-1.0 ℃/mm.

In an alternative embodiment, the graphite crucible is placed in a vacuum chamber formed by a quartz tube, the quartz tube has a double-layer structure, and cooling water is arranged between the double-layer structure.

In an alternative embodiment, the thermal insulation material has a thermal conductivity that varies from 700 to 1000 times that of the graphite crucible.

In an optional embodiment, a first temperature measuring unit is arranged at the top of the graphite crucible, a second temperature measuring unit is arranged at the bottom of the graphite crucible, and the two temperature measuring units are used for monitoring temperature gradient changes in the furnace body.

In an alternative embodiment, a seed crystal is provided on top of the graphite crucible, and the seed crystal is disposed at the mounting position by an adhesive material.

In an alternative embodiment, the top of the seed crystal is provided with a heating module.

In an alternative embodiment, the adhesive material is a carbon-containing binder.

In an alternative embodiment, the vacuum degree in the furnace body is about 5 multiplied by 10 under the working condition ^-2 Pa。

In an alternative embodiment, the bottom of the graphite crucible is filled with SiC raw material, which is in powder form.

The technical scheme of the utility model has the following advantages or beneficial effects:

(1) The outer surface of the graphite crucible is coated with a heat insulation material, so that the heat dissipation effect of the graphite crucible can be reduced, the heat insulation performance of the graphite crucible is improved, and the stable thermal field environment is formed inside the graphite crucible. The heating device comprises a coil, the position of the coil can move along the axis direction of the furnace body, and the current and/or voltage of the coil can be controlled in a layered manner; the heating position of the coil can be adjusted by a user conveniently, the temperature of the specific position of the graphite crucible can be controlled, and the temperature field distribution in the crucible can be adjusted by combining two temperature adjustment means, so that the flexibility and the reliability of temperature adjustment are effectively improved. In the working state, the highest temperature point in the furnace body is at the position from top to bottom about 60% in the axial direction of the graphite crucible, the upward temperature gradient of the position is in a first threshold range, the downward temperature gradient of the position is in a second threshold range, and the lower limit value of the first threshold range is larger than the upper limit value of the second threshold range. The crystal generation efficiency of the method is obviously superior to that of the prior art, and the size of the crystal block can be improved.

(2) The graphite crucible is placed in a vacuum chamber formed by quartz tubes, the quartz tubes are of a double-layer structure, and cooling water is arranged between the double-layer structure; the arrangement can effectively improve the sealing performance of the graphite crucible by placing the graphite crucible in a double-layer quartz tube; and cooling water is introduced between the double-layer quartz structures so as to be convenient for adjusting the temperature in the growth device.

(3) The top of the graphite crucible is provided with a first temperature measuring unit, the bottom of the graphite crucible is provided with a second temperature measuring unit, and the two temperature measuring units are used for monitoring the temperature gradient change in the furnace body; the two temperature measuring units are arranged, so that a user can conveniently observe the temperature and the temperature gradient distribution in the crucible, and the heating assembly in the crucible is regulated according to the temperature gradient distribution, so that a stable temperature field is formed in the crucible.

(4) A heating module is arranged at the top of the seed crystal; the heating module not only can control the longitudinal temperature gradient in the crucible, but also can perform annealing treatment; the flexibility of the operation of the device is improved; the device can still ensure the quality of the crystal in the process of producing the crystal with high efficiency.

Drawings

The drawings are included to provide a better understanding of the utility model and are not to be construed as unduly limiting the utility model. Wherein:

FIG. 1 is a schematic cross-sectional view of a principal structure of a single crystal type SiC crystal growth apparatus according to an embodiment of the utility model;

FIG. 2 is a schematic diagram showing the change of temperature gradient inside the crystal growing apparatus according to the embodiment of the present utility model;

FIG. 3 is a schematic front view of another apparatus for growing crystals according to an embodiment of the present utility model;

fig. 4 is a schematic top view of another apparatus for growing crystals according to an embodiment of the present utility model.

Detailed Description

Exemplary embodiments of the present utility model will now be described with reference to the accompanying drawings, in which various details of the embodiments of the present utility model are included to facilitate understanding, and are to be considered merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the utility model. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.

The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited by these terms. These terms are only used to distinguish one type of information from another. For example, a first message may also be referred to as a second message, and similarly, a second message may also be referred to as a first message, without departing from the scope of the present application. The word "if" as used herein may be interpreted as "at … …" or "at … …" or "in response to a determination", depending on the context.

In the prior art, the SiC crystal growth device mainly uses induction type crystal growth equipment, and products produced by the device can meet the market demand for 4 inch mainstream products in a short time. However, the demand of more than 6 inches, even 8 inches SiC monocrystal blocks in the future market is greatly increased, and the product cannot meet the demand of the market on large-size wafers due to the fact that the crystal growth device cannot meet the high yield. In addition, various single crystal SiC production processes are disclosed in the prior art, but documents corresponding to production equipment and procedures are rarely disclosed. Thus, there is a problem that the thermal stress generated by slip defects (split defects) or basal plane dislocation (basal plane dislocation) in silicon carbide crystallization occurs because the seed crystal is positioned on the seed holder to move or fall, or at least the main growth gradient cannot occur at a predetermined angle due to an uncertain factor of the mechanical structure of the device. Or, such a production process does not mention the time to interrupt the epitaxial growth, and after the SiC wafer is cut due to the uncertain factors existing in the mechanical structure of the device, surface morphology defects caused by crystal defects in the material are found when epitaxial wafer processing is applied, so that the reverse leakage current is increased, and the yield cannot be improved. One major cause of the high cost of SiC components in current industrial production is the difficulty in manufacturing SiC substrates. The SiC substrate cost is about 50% of the total chip processing cost, the epitaxial chip is about 25%, the device wafer fabrication process is about 20%, and the package test process is about 5%. It follows that the SiC substrate has a very high ratio in the total cost. Furthermore, siC substrates are not only expensive, but also the production process is very complex. SiC is difficult to handle compared to silicon processing. Unlike conventional single crystal silicon production using the Czochralski process, currently large-scale growth of SiC single crystals is mainly performed by Physical Vapor Transport (PVT) or seeded sublimation. This also presents two difficulties in the preparation of SiC crystals. 1. The growth conditions are harsh: current single crystal SiC production needs to be performed under high temperature conditions. In general, siC vapor phase growth temperature is 2300℃or higher and pressure is 350MPa. And monocrystalline silicon only needs about 1600 ℃. The high temperatures required for SiC production place extremely high demands on equipment and process control, and therefore the production process of the process is almost black box operation, and it is difficult for operators to observe the internal environmental conditions of the production equipment. If there is a slight error in temperature and pressure control, product failure can result in several days of growth. 2. The growth rate is slow. The PVT method has a slow growth rate of SiC, and can grow for about 2cm only for 7 days. In addition, single crystal growth defects are also a major problem in the current production of single crystal SiC, such as threading dislocation and micropipe problems in large area applications of SiC chips. The large-scale production of SiC chips still has some technical process problems when the low microtubule density or zero defect quality is achieved, which is one of the core problems restricting the improvement of the yield.

To solve at least one of the above technical problems, an embodiment of the present disclosure provides a single crystal SiC growing apparatus, including: a furnace body and a heating device; a graphite crucible is arranged in the furnace body, and the outer surface of the graphite crucible is coated with a heat insulation material; the heating device comprises a coil, the position of the coil can move along the axis direction of the furnace body, and the current and/or voltage of the coil can be controlled in a layered manner; under the working state, the highest temperature point in the furnace body is at the position from top to bottom about 60% in the axial direction of the graphite crucible, the upward temperature gradient of the position is in a first threshold range, the downward temperature gradient of the position is in a second threshold range, and the lower limit value of the first threshold range is larger than the upper limit value of the second threshold range.

The difficulty with existing SiC column (or ingot) growth techniques is due to the low defect density and single phase crystals that are grown. For this purpose, precise control of the thermal field distribution and the technical parameters of the heating module is required. Therefore, the present disclosure provides a novel single crystal SiC growth device, by reasonably controlling the distribution of the temperature field, the longitudinal and radial temperature gradients in the growth device are increased to increase the growth rate without affecting the crystal quality; thereby solving the problem of low production speed of single crystal SiC in the prior art. In particular, referring to the embodiment shown in fig. 1 and 2, a cross-sectional view of a schematic structural diagram of a single crystal type SiC growth apparatus is disclosed. It is to be understood that the foregoing drawings clearly illustrate the main structure of the present device, and those skilled in the art can repeatedly manufacture the technical solutions of the present disclosure based on the descriptions and illustrations herein. Accordingly, fig. 3 and 4 show a schematic diagram of the overall structure manufactured according to the structural principle shown in fig. 1 and 2. Specifically, the crystal growth device comprises: the furnace body 106 and the heating device. The furnace 106 is internally provided with a crucible 104, and the crucible is used for bearing raw materials. In the preferred embodiment, the crucible is a graphite crucible, and the graphite crucible has excellent high-temperature resistance and can effectively meet the high-temperature environment requirement for SiC production. Further, in order to make the crucible have good heat insulation and improve energy utilization efficiency, the outer surface of the graphite crucible in this embodiment is further coated with a heat insulating material 103. Preferably, the thermal insulation material is selected from graphite thermal insulation materials, which are only examples, and other materials capable of achieving the same thermal insulation effect can be equivalently replaced, so that the graphite thermal insulation material does not limit the protection scope of the present disclosure. The heating device comprises a coil 101, wherein the position of the coil 101 can move along the axis direction of the furnace body, and the current and/or voltage of the coil can be controlled in a layered manner. In order to effectively control the distribution of the thermal field inside the growth device, it is important how to control the working state of the heating device. Therefore, the working state of the heating device is adjusted from two angles to control the temperature field distribution inside the crystal growth device, and the combination of the two means not only improves the flexibility of adjustment, but also improves the reliability of temperature adjustment. Specifically, the coil in the embodiment is an induction coil, which can generate heat after being loaded with current, so as to heat the crucible arranged in the coil. The position of the coil described in this disclosure is adjustable. In the embodiment shown in fig. 1, the crucible is integrally arranged inside the coil, and the axes between the crucible and the crucible are coaxial or basically coaxial, and the position of the coil can move up and down, that is, the position of the coil relative to the crucible is adjustable; thereby realizing heating of different positions of the crucible. Furthermore, the coils are arranged in a layered structure, each layer of coils can be independently loaded with current or voltage, and the current and voltage applied in layers can be different. It is understood that the heat generated by the coil is approximately positively correlated to the current or voltage, and the heat generation of the coil can be controlled by adjusting the current or voltage. In addition, the temperature field inside the crucible at the corresponding position can be controlled by controlling the coils of the corresponding layers. Through the two means, an operator can flexibly heat the graphite crucible, and further control to obtain a required internal temperature field. Further, in the working state, the highest temperature point in the furnace body is at the position from top to bottom about 60% in the axial direction of the graphite crucible, the upward temperature gradient of the position is in a first threshold range, the downward temperature gradient of the position is in a second threshold range, and the lower limit value of the first threshold range is larger than the upper limit value of the second threshold range. Experiments prove that the growth speed of single crystal SiC can be effectively improved by reasonably controlling the position of a high temperature point in the furnace body and the distribution of the temperature gradient. In the embodiment shown in fig. 1, the furnace body and the crucible are vertically placed, and in this placement posture, when the highest temperature point in the furnace body is at a position from top to bottom of about 60% in the axial direction of the graphite crucible, and the temperature gradient of the temperature field above this position is larger than the temperature gradient of the temperature field below this position, the temperature gradient in the longitudinal (or so-called axial) direction and the radial direction of the crucible can be increased, thereby improving the growth efficiency of SiC. Specifically, sublimation (sublimation) and deposition (deposition) occur simultaneously on the feedstock and growth interface in a seeded environment. Crystals will grow only if the rate of deposition is greater than the rate of sublimation. If the temperature gradient in the axial direction of the crucible is too small, the temperature of the growth interface is too close to the sublimation temperature of the raw materials, so that the sublimation rate of the growth interface is too high, and even the seed crystal is sublimated, and the growth cannot be realized. Conversely, if the axial temperature gradient is too large, the SiC gas is deposited before reaching the growth interface, so that excessive nucleation sites are generated in the space between the raw material and the interface, and polycrystal is formed, and even the polycrystal cannot be grown. An appropriate temperature gradient is a necessary condition for driving crystal growth and also affects the quality of the crystals. Therefore, the method and the device can effectively control the axial temperature gradient and the radial temperature gradient in the crucible by reasonably arranging the position of the highest temperature point in the crucible and the temperature gradient change rule of the temperature field in the crucible, thereby improving the production speed on the premise of ensuring the growth quality of single crystal SiC. Also, control of the temperature gradient makes it possible to eliminate the problem of polymorphic inclusions, and also to eliminate the problem of thermal stress due to sliding defects or basal plane misalignment.

In an alternative embodiment, the first threshold range is 1.5-2.0 ℃/mm and the second threshold range is 0.8-1.0 ℃/mm. In this embodiment, the lower limit of the temperature gradient in the portion above the highest temperature point in the crucible is about 1.5 ℃/mm, and the upper limit of the temperature gradient in the portion above the highest temperature point is about 1.0 ℃/mm. That is, the temperature gradient of the upper region is large, enabling SiC deposition and avoiding sublimation of the grown single crystal; and the temperature gradient of the raw material part in the lower area is small, so that SiC can be ensured to be in a sublimated state and deposited at the interface.

In an alternative embodiment, the graphite crucible is placed in a vacuum chamber formed by a quartz tube, the quartz tube has a double-layer structure, and cooling water is arranged between the double-layer structure. Considering that the temperature field in a graphite crucible is very high in temperature, the growth quality of crystals is greatly affected after impurity particles or gas are mixed into the crucible. For this purpose, in one example of the present disclosure, a crucible is placed in a vacuum chamber formed of a double-layered quartz tube. The double-layer structure can effectively ensure the tightness. Furthermore, the double-layer quartz tube can be filled with cooling water to adjust the temperature in the crystal growing device.

In an alternative embodiment, the thermal insulation material has a thermal conductivity that varies from 700 to 1000 times that of the graphite crucible. In one embodiment, the thermal insulation material or materials coated on the surface of the graphite crucible needs to have good thermal insulation performance, so as to avoid energy waste caused by heat exchange between the interior of the crucible and the rapid environment. In one embodiment, the thermal insulation material has a thermal conductivity that differs from the graphite crucible by a factor of 700 to 1000; that is, the thermal conductivity of the insulating material is significantly weaker than that of the graphite crucible, so that the temperature field in the crucible is stable. It will be appreciated that in the absence of insulating material, the operator needs to detect the temperature field changes in the crucible at all times and to control the operation of the coils in real time to maintain the temperature values and temperature gradients in the crucible.

In an alternative embodiment, the graphite crucible is provided with a first temperature measuring unit 107 at the top and a second temperature measuring unit 108 at the bottom, and the two temperature measuring units are used for monitoring the temperature gradient change in the furnace body. As previously described, axial temperature gradient control within the crucible is a significant factor in maintaining the growth rate of single crystal type SiC, and for this purpose, the present disclosure monitors the temperature of the graphite crucible by providing a temperature measurement unit at the top and bottom of the crucible, respectively, and calculates the temperature gradient within the crucible from the temperature. In an alternative embodiment, the temperature measuring unit may be an infrared high temperature detector. In one embodiment as shown in fig. 2, it simply shows the temperature gradient profile inside the crucible. Specifically, in actual measurement, the first temperature measuring unit may be placed close to the seed crystal 102, and the temperature of the measuring point is close to the temperature of the seed crystal. Accordingly, the second temperature measuring unit is placed as close as possible to the bottom of the crucible, which is substantially capable of reflecting the temperature of the raw material at the bottom of the crucible. In the example shown in fig. 2, the temperature field distribution inside the crucible is fitted by a linear equation. This embodiment is only a simple example, and a plurality of temperature measuring units may be provided in actual use to comprehensively detect the distribution of the temperature field, thereby obtaining more accurate axial temperature gradient and radial temperature gradient in the crucible.

In an alternative embodiment, a seed crystal is provided on top of the graphite crucible, and the seed crystal is disposed at the mounting position by an adhesive material. In the embodiment shown in fig. 1 and 2, a seed crystal or seed crystal is disposed on top of the crucible. To facilitate securing the seed crystal, in one embodiment of the present disclosure, it is secured to the top of the crucible by bonding or adhesive means. The adhesive material is usually a high-purity, high-temperature-resistant and easy-to-smear material. The material can stably work in a high-temperature environment without causing seed crystal falling off, and ensures the stable production process.

In an alternative embodiment, the top of the seed crystal is provided with a heating module. In an alternative embodiment, siC crystal growth is accomplished primarily by vapor phase to solid phase, with resistive heating taking particular attention to the temperature at the bottom of the crucible and the abrupt change in temperature gradient. In a preferred embodiment, a heating module is installed on the top of the seed crystal, the heating module can be regulated by a temperature controller of a control module of a different coil, and the heating module can be used for controlling the longitudinal temperature gradient and also carrying out annealing treatment on the SiC crystal.

In an alternative embodiment, the adhesive material is a carbon-containing binder. Preferred are high carbon content binders including, but not limited to, graphite (Graphite adhesives), AB and 502 binders of various high carbon content.

In an alternative embodiment, the vacuum degree in the furnace body is about 5 multiplied by 10 under the working condition ^-2 Pa. SiC growth requires a very clean environment because at high temperatures even very small amounts of impurities can affect the quality of the crystal and further affect its semiconductor properties. The source of impurities is typically non-carbon silicon system elements that are not removed from the stack, feedstock, and ambient gas. Therefore, it is necessary to clean the crucible interior environment before growth. Preferably, the crucible may be subjected to a vacuum treatment to discharge impurity gas therein.

In an alternative embodiment, the bottom of the graphite crucible is filled with SiC feedstock 105, which is in powder form. The raw materials used for growing SiC crystals are mainly high-strength, high-density and high-purity graphite. The raw materials are placed at the bottom of the crucible.

In an alternative embodiment, as shown in the examples of fig. 3 and 4, the housing of the device may further be provided with a man-machine interaction interface 201, where the man-machine interaction interface may be a display screen or the like, which may facilitate an operator to observe working parameters such as temperature, vacuum degree and the like in the device in real time, and also facilitate the operator to control the working parameters.

Illustratively, the working process of the SiC growth device of the present disclosure is as follows:

1. placing a SiC raw material (which is in a powder state and is above 5N grade) into a graphite crucible below the device at a high temperature of about 2400 ℃, and adhering SiC seed crystals to the upper end of a thermal field and adhering conductive graphite with high purity, high temperature resistance and easy coating;

2. the graphite crucible is coated with a graphite heat-insulating material and is placed in a vacuum chamber formed by a quartz tube;

3. constant-temperature cooling water is introduced into the middle of the double-layer quartz tube;

4. the graphite crucible is arranged at the center of the induction coil;

5. the coil position can move up and down, different currents and voltages are applied in layers, and heating of the graphite crucible is adjusted;

6. by controlling the temperature and the pressure of the growth chamber, the SiC raw material sublimates from the lower part of the crucible and rises to the seed crystal to carry out stacking growth, and finally SiC monocrystal is obtained; si ions and C ions sublimated from the SiC raw material may constitute by-product gases such as Si (g), si2C (g), siC2 (g) and the like, and the concentration of these by-product gases also affects the effect of SiC crystal growth, so that the state energy barrier from physical adsorption force to chemical adsorption force can be reduced as much as possible by the grown crystal section to reduce the reaction effect thereof.

When the device disclosed by the utility model is used for generating SiC crystals, the primary growth period is 10 days, and the length of mass production crystal columns can reach 40-60mm after the adjustment is finished. The device can continuously and stably run for more than ten days at the temperature of 2400 ℃. The wafer blocks produced by the device can cut wafers with the thickness of 0.5mm and even wafers with the thickness of 0.325 mm; and microtubes (micropipes) of less than 5MPs/cm ² The method comprises the steps of carrying out a first treatment on the surface of the The resistivity is about 0.010 to 0.028Ω cm ² The method comprises the steps of carrying out a first treatment on the surface of the A thermal conductivity (Thermal conductivity) greater than 4.5W/cmK; melting point (mering point) greater than 2100 ℃; electron mobility Thermal conductivity>4.5 (W/cmK); the electron mobility (Electron mobility) is about 700 cm to about 1000cm ² /Vs。

The above embodiments do not limit the scope of the present utility model. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed subject matter. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A single crystal SiC growth apparatus comprising:

a furnace body and a heating device;

the method is characterized in that:

2. The apparatus according to claim 1, wherein,

the first threshold range is 1.5-2.0 ℃/mm, and the second threshold range is 0.8-1.0 ℃/mm.

3. The apparatus according to claim 1, wherein,

the graphite crucible is placed in a vacuum chamber formed by quartz tubes, the quartz tubes are of a double-layer structure, and cooling water is arranged between the double-layer structure.

4. The apparatus according to claim 1, wherein,

the thermal conductivity of the thermal insulation material and the thermal conductivity of the graphite crucible are different by 700 to 1000 times.

5. The apparatus according to claim 1, wherein,

the top of graphite crucible is provided with first temperature measuring unit, and the bottom is provided with second temperature measuring unit, two temperature measuring units be used for monitoring the temperature gradient change in the furnace body.

6. The apparatus according to claim 1, wherein,

the top of graphite crucible is provided with the seed crystal, the seed crystal passes through the adhesion material and sets up in the mounted position.

7. The apparatus according to claim 6, wherein,

the top of seed crystal is provided with the heating module.

8. The apparatus according to claim 6, wherein,

the adhesive material is a carbon-containing element adhesive.

9. The apparatus according to claim 1, wherein,

in the working state, the vacuum degree in the furnace body is 5 multiplied by 10 ^-2 Pa。

10. The apparatus according to claim 1, wherein,

and filling SiC raw materials at the bottom of the graphite crucible, wherein the SiC raw materials are in powder form.