Silicon carbide single crystal growth apparatus, silicon carbide single crystal growth furnace, and silicon carbide single crystal growth method

Abstract

This application discloses a silicon carbide single crystal growth apparatus, a silicon carbide single crystal growth furnace, and a silicon carbide single crystal growth method. The silicon carbide single crystal growth apparatus includes: a crucible having a sublimation chamber, a gas mixing chamber, and a crystallization chamber, which are distributed and connected along a first direction; a heating device disposed in the crucible and used to heat the sublimation chamber, the gas mixing chamber, and the crystallization chamber; a gas injection device for injecting epitaxial gas into the gas mixing chamber, the epitaxial gas including a silicon source, a carbon source, and an auxiliary gas; a first porous graphite plate and a second porous graphite plate, the first porous graphite plate being disposed at the bottom end of the gas mixing chamber near the sublimation chamber, and the second porous graphite plate being disposed at the top end of the gas mixing chamber near the crystallization chamber. This silicon carbide single crystal growth apparatus can increase the crystal growth thickness and reduce the difficulty of crystal growth.

Description

Technical Field

[0001] This application relates to the field of silicon carbide single crystal growth technology, and more specifically, to a silicon carbide single crystal growth apparatus, a silicon carbide single crystal growth furnace, and a silicon carbide single crystal growth method. Background Technology

[0002] The growth of silicon carbide single crystals using the PVT (Physical Vapor Transport) method mainly increases the material flow supply by increasing the amount of raw material loaded into the crucible, thereby increasing the growth thickness of the crystal (silicon carbide single crystal).

[0003] However, increasing the supply of material flow by adding more silicon carbide powder will lead to a larger temperature gradient in the entire crucible, increased uneven heating of the raw materials, and internal crystallization of the raw materials, which will hinder the smooth transport of material flow and make it more difficult to grow thick crystals.

[0004] In summary, how to increase the growth thickness of crystals to reduce the difficulty of growing thicker crystals is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a silicon carbide single crystal growth apparatus, a silicon carbide single crystal growth furnace, and a silicon carbide single crystal growth method to reduce the difficulty of growing thick crystals.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A silicon carbide single crystal growth apparatus, comprising:

[0008] A crucible having a sublimation chamber, a gas mixing chamber, and a crystallization chamber, wherein the sublimation chamber, the gas mixing chamber, and the crystallization chamber are distributed along a first direction and are connected to each other;

[0009] A heating device is disposed in the crucible and is used to heat the sublimation chamber, the gas mixing chamber, and the crystallization chamber;

[0010] A gas injection device is used to inject epitaxial gas into the gas mixing chamber, the epitaxial gas including a silicon source, a carbon source, and an auxiliary gas;

[0011] A first porous graphite plate and a second porous graphite plate are disposed at the bottom end of the gas mixing chamber near the sublimation chamber, and the second porous graphite plate is disposed at the top end of the gas mixing chamber near the crystallization chamber.

[0012] In some possible embodiments, the second porous graphite plate is a curved plate, and the second porous graphite plate is arranged to protrude towards the bottom end of the gas mixing chamber along the first direction.

[0013] In some possible embodiments, the radius of curvature of the second porous graphite plate is 50cm-500cm.

[0014] In some possible embodiments,

[0015] The porosity of the first porous graphite plate is 30%-80%, and the thickness of the first porous graphite plate is 1mm-10mm.

[0016] And / or, the porosity of the second porous graphite plate is 30%-80%, and the thickness of the second porous graphite plate is 0.5mm-2mm.

[0017] In some possible embodiments, the heating device includes a first heater, a second heater, and a third heater, any two of which are independent of each other. The first heater is used to heat the sublimation chamber, the second heater is used to heat the gas mixing chamber, and the third heater is used to heat the crystallization chamber.

[0018] In some possible embodiments, the first heater includes a lower heater and a first side heater, the lower heater being located at the bottom end of the sublimation chamber and the first side heater surrounding the periphery of the sublimation chamber;

[0019] And / or, the second heater surrounds the periphery of the gas mixing chamber;

[0020] And / or, the third heater includes an upper heater and a third side heater, the upper heater being located at the top of the crystallization chamber and the third side heater surrounding the periphery of the crystallization chamber;

[0021] And / or, the first heater, the second heater and the third heater are all graphite heaters.

[0022] In some possible embodiments, the gas injection device includes: a manifold passing through the crucible, and a first delivery pipe, a second delivery pipe, and a third delivery pipe all connected to the manifold;

[0023] The first conveying pipe is used to convey the carbon source, the second conveying pipe is used to convey the silicon source, and the third conveying pipe is used to convey the auxiliary gas. The first conveying pipe, the second conveying pipe, and the third conveying pipe are all connected in series with a flow regulating device.

[0024] In some possible embodiments, the silicon carbide single crystal growth apparatus further includes a flow guide ring disposed in the sublimation cavity, the outer wall of the flow guide ring being in contact with the inner wall of the sublimation cavity, the inner cavity of the flow guide ring being tapered along a first direction, and the larger end of the inner cavity being closer to the bottom end of the sublimation cavity than the smaller end.

[0025] Based on the silicon carbide single crystal growth apparatus provided above, this application also provides a silicon carbide single crystal growth furnace, which includes: a furnace body and the silicon carbide single crystal growth apparatus described in any one of the above claims, wherein the furnace body has a growth chamber and the silicon carbide single crystal growth apparatus is located in the growth chamber.

[0026] Based on the silicon carbide single crystal growth furnace provided above, this application also provides a silicon carbide single crystal growth method. The silicon carbide single crystal growth method uses the silicon carbide single crystal growth furnace described in any of the above embodiments to grow silicon carbide single crystals. The silicon carbide single crystal growth method includes:

[0027] Polycrystalline powder is loaded into the sublimation chamber of the crucible, and the seed crystal is fixed at the top of the crystallization chamber of the crucible.

[0028] Evacuate the growth chamber;

[0029] A protective gas is introduced into the growth chamber;

[0030] Start the heating device until the temperature of the crystallization chamber is 2000℃-2400℃ and the temperature of the sublimation chamber is 2100℃-2400℃, and the temperature of the sublimation chamber is greater than the temperature of the crystallization chamber;

[0031] Epitaxial gas, including silicon source, carbon source and auxiliary gas, is injected into the gas mixing chamber of the crucible through a gas injection device to achieve mixed growth.

[0032] In the silicon carbide single crystal growth apparatus provided in this application, the sublimation chamber can hold polycrystalline powder, which can continuously sublimate at a first set temperature to provide a basic growth material flow (e.g., Si, SixCy). The gas injection device can inject epitaxial gas into the gas mixing chamber. The epitaxial gas can undergo pyrolysis and chemical reaction at a second set temperature to generate highly active Si / C gaseous species and additional SiC gaseous molecules in situ. The mixed gas phase generated by sublimation and the mixed gas phase generated by the reaction with the epitaxial gas are mixed and then enter the crystallization chamber through the second porous graphite plate. This can effectively supplement and enhance the growth material flow delivered to the seed crystal. Compared with the PVT method, it can realize a synergistic growth mechanism of the two methods, which can improve the growth rate and increase the growth thickness of the single crystal.

[0033] In the silicon carbide single crystal growth apparatus provided in this application embodiment, epitaxial gas is injected into the gas mixing chamber through a gas injection device to supplement and enhance the growth material flow delivered to the seed crystal. Compared with increasing the amount of silicon carbide powder to increase the material flow supply, this can reduce the probability and degree of internal crystallization of the raw material (polycrystalline powder), reduce the impact on material flow transportation, and reduce the difficulty of growing a thick single crystal. It can also reduce the amount of raw material required, reduce the impact of diminishing marginal returns, and even eliminate the diminishing marginal returns effect, thereby improving the utilization rate of silicon carbide powder and reducing the cost of crystal growth. By adjusting the flow rate of silicon source in the epitaxial gas and the flow rate of carbon source in the epitaxial gas, the fluctuation of crystal quality in the early and late stages can be reduced, and the controllability of crystal quality can be improved.

[0034] In the silicon carbide single crystal growth apparatus provided in this application embodiment, the gas can be buffered in the gas mixing chamber and the gas pressure can be balanced under the combined action of the first porous graphite plate and the second porous graphite plate. This can reduce the probability of local component accumulation on the crystal growth surface and the degree of deviation of the carbon-silicon ratio from the ideal state, thereby reducing the probability of generating a large number of crystal defects such as impurities, microtubes and dislocations.

[0035] The technical features mentioned above, as well as those shown individually in the accompanying drawings, can be combined arbitrarily, provided that the combined technical features are not contradictory. All feasible combinations of features are the technical content explicitly described herein. Any one of the multiple sub-features contained in the same statement can be applied independently, without necessarily being applied together with other sub-features. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of the silicon carbide single crystal growth apparatus provided in the embodiments of this application;

[0038] Figure 2 This is a schematic diagram of the flow guide ring in the silicon carbide single crystal growth apparatus provided in the embodiments of this application;

[0039] Figure 3 This is a front view of the second porous graphite plate in the silicon carbide single crystal growth apparatus provided in the embodiments of this application;

[0040] Figure 4This is a top view of the second porous graphite plate in the silicon carbide single crystal growth apparatus provided in the embodiments of this application;

[0041] Figure 5 This is a schematic diagram of the structure of a silicon carbide single crystal growth furnace provided in an embodiment of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 100 - Silicon carbide single crystal growth apparatus, 200 - Furnace body, 201 - Growth chamber;

[0044] 1-Crucible, 11-Sublimation chamber, 111-First part of sublimation chamber, 112-Second part of sublimation chamber, 12-Gas mixing chamber, 13-Crystallization chamber;

[0045] 2-Heating device, 21-First heater, 211-Lower heater, 212-First side heater, 22-Second heater, 23-Third heater, 231-Upper heater, 232-Third side heater;

[0046] 3-Gas injection device, 31-First delivery pipe, 32-Second delivery pipe, 33-Third delivery pipe, 34-Manifold;

[0047] 4-First porous graphite plate;

[0048] 5-Second porous graphite plate;

[0049] 6-Guide ring, 61-Guide cavity;

[0050] 7-Insulation layer;

[0051] 8-Flow regulating device;

[0052] 01-Single crystal, 02-Polycrystalline powder, 03-Seed crystal. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the embodiments of this application, “one or more” means one, two, or more; “and / or” describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0055] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0056] The "multiple" mentioned in the embodiments of this application refers to two or more. It should be noted that in the description of the embodiments of this application, terms such as "first" and "second" are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0057] The terms "parallel" and "perpendicular" used in this application refer to "basically parallel" and "basically perpendicular" in practical operation. "Basically parallel" can be understood as parallelism with a certain degree of error, and similarly, "basically perpendicular" can be understood as perpendicularity with a certain degree of error.

[0058] like Figure 1 As shown, the silicon carbide single crystal growth apparatus 100 provided in this application embodiment includes: a crucible 1, a heating device 2, a gas injection device 3, a first porous graphite plate 4, and a second porous graphite plate 5.

[0059] It should be noted that, Figure 1This is a cross-sectional view of the silicon carbide single crystal growth apparatus 100. The crucible 1 can be made of graphite and has a closed structure. The crucible 1 has a sublimation chamber 11, a gas mixing chamber 12, and a crystallization chamber 13, which are distributed and connected along a first direction. It should be noted that the first direction is the height direction of the crucible 1.

[0060] It is understandable that the cavity formed by the connection of the sublimation cavity 11, the gas mixing cavity 12, and the crystallization cavity 13 is a closed cavity.

[0061] The bottom of the sublimation chamber 11 is used to place polycrystalline powder 02, which is silicon carbide polycrystalline powder. The top of the crystallization chamber 13 is used to fix the seed crystal 03, which is a silicon carbide seed crystal.

[0062] The heating device 2 is disposed on the crucible 1. For example, the heating device 2 can be disposed outside the crucible 1 to facilitate the installation of the heating device 2. The heating device 2 is used to heat the sublimation chamber 11, the gas mixing chamber 12, and the crystallization chamber 13.

[0063] The heating device 2 described above can be a graphite heating device or other types, and this application embodiment does not limit this.

[0064] To ensure the temperature of each cavity in crucible 1, the silicon carbide single crystal growth apparatus 100 also includes a heat insulation layer 7, which covers the outer surface of the assembly formed by the crucible 1 and the heating device 2. The type of heat insulation layer 7 is selected according to the actual situation; for example, the heat insulation layer 7 may be a heat insulation felt. This embodiment of the application does not limit this.

[0065] The gas injection device 3 is used to inject epitaxial gas into the gas mixing chamber 12. The epitaxial gas includes silicon source, carbon source and auxiliary gas.

[0066] The silicon source may include silane or trichlorosilane, the carbon source may include ethylene, acetylene or methane, and the auxiliary gas may include at least one of a carrier gas and a dopant gas. The carrier gas may include hydrogen, and the dopant gas may include nitrogen or ammonia.

[0067] Hydrogen helps suppress the formation of silicon droplets in the silicon carbide gas phase and can passivate crystal growth steps, promoting two-dimensional nucleation.

[0068] Both the first porous graphite plate 4 and the second porous graphite plate 5 have porous structures, and both can allow growth material to flow through them.

[0069] like Figure 1As shown, the gas mixing chamber 12 has a top end and a bottom end along the first direction. The bottom end of the gas mixing chamber 12 is close to the sublimation chamber 11, and the top end of the gas mixing chamber 12 is close to the crystallization chamber 13. The first porous graphite plate 4 is disposed at the bottom end of the gas mixing chamber 12, and the second porous graphite plate 5 is disposed at the top end of the gas mixing chamber 12.

[0070] The porosity of the first porous graphite plate 4 and the second porous graphite plate 5 can be equal or unequal. To ensure smooth gas flow, the porosity of the first porous graphite plate 4 can be 30%-80%, and the porosity of the second porous graphite plate can be 30%-80%. For example, the porosity of the first porous graphite plate can be 30%, 50%, or 80%, and the porosity of the second porous graphite plate can be 30%, 50%, or 80%.

[0071] The thicknesses of the first porous graphite plate 4 and the second porous graphite plate 5 can be equal or unequal. Since the first porous graphite plate 4 is close to the sublimation chamber 11 and the second porous graphite plate 5 is close to the crystallization chamber 13, the temperature of the sublimation chamber 11 can be higher than the temperature of the crystallization chamber 13. Therefore, in order to ensure the service life of the first porous graphite plate 4, the thickness of the first porous graphite plate 4 can be greater than the thickness of the second porous graphite plate 5.

[0072] To ensure the strength of the first porous graphite plate 4, its thickness can be 1mm-10mm. For example, the thickness of the first porous graphite plate can be 1mm, 5mm, or 10mm. To ensure the strength of the second porous graphite plate 5, its thickness can be 0.5mm-2mm. For example, the thickness of the second porous graphite plate can be 0.5mm, 1mm, or 2mm.

[0073] In the silicon carbide single crystal growth apparatus 100 provided in this application embodiment, the sublimation chamber 11 can hold polycrystalline powder 02, which can continuously sublimate at a first set temperature to provide a basic growth material flow (e.g., Si, SixCy); the gas injection device 3 can inject epitaxial gas into the gas mixing chamber 12. The epitaxial gas can undergo pyrolysis and chemical reaction at a second set temperature to generate highly active Si / C gaseous species and additional SiC gaseous molecules in situ. The mixed gas phase generated by sublimation and the mixed gas phase generated by the reaction with the epitaxial gas are mixed and then enter the crystallization chamber 13 through the second porous graphite plate 5. This can effectively supplement and enhance the growth material flow delivered to the seed crystal 03. Compared with the PVT method, a synergistic growth mechanism of the two methods can be achieved, which can improve the growth rate, for example, by more than 20%-50%, and can also increase the growth thickness of the single crystal 01, for example, the growth thickness of the single crystal 01 can be greater than 30 mm.

[0074] In the silicon carbide single crystal growth apparatus 100 provided in this application embodiment, epitaxial gas is injected into the gas mixing chamber 12 through the gas injection device 3 to supplement and enhance the growth material flow delivered to the seed crystal 03. Compared with increasing the material flow supply by increasing the amount of silicon carbide powder, this can reduce the probability and degree of internal crystallization of the raw material (polycrystalline powder 02), reduce the impact on material flow transportation, and reduce the difficulty of growing the single crystal (crystal) 01.

[0075] In the PVT (Physical Vapor Transport) method, increasing the growth thickness of the crystal by adding more raw materials results in a diminishing marginal returns effect. A large amount of carbonized silicon carbide powder remains, reducing the utilization rate of the silicon carbide powder and increasing the cost of crystal growth. However, in the silicon carbide single crystal growth apparatus 100 provided in this application embodiment, epitaxial gas is injected into the gas mixing chamber 12 to supplement and enhance the flow of growth material delivered to the seed crystal 03. This reduces the amount of raw materials required, mitigates the diminishing marginal returns effect, and can even eliminate it, thereby improving the utilization rate of silicon carbide powder and ultimately reducing the cost of crystal growth.

[0076] In the PVT (Physical Vapor Transport) method, silicon is easily separated from the silicon carbide raw material in the early stages of growth, resulting in a silicon-rich atmosphere. As the growth time increases, silicon gradually dissipates, and the atmosphere inside the crucible becomes carbon-rich. This state transition and uncertainty lead to fluctuations in crystal quality throughout the growth process, making it difficult to effectively control crystal quality. However, in the silicon carbide single crystal growth apparatus 100 provided in this application, by adjusting the flow rates of the silicon source and carbon source in the epitaxial gas, the fluctuations in crystal quality throughout the growth process can be reduced, thus improving the controllability of crystal quality.

[0077] The silicon carbide single crystal growth apparatus 100 provided in this application provides a method for growing silicon carbide single crystals that, compared with the HTCCVD (High-Temperature Chemical Vapor Deposition) method, can reduce the consumption of high-purity epitaxial gas and the complexity of the system; compared with the PVT method, it can improve production efficiency and crystal quality, and improve the overall cost-effectiveness of the silicon carbide single crystal growth apparatus 100.

[0078] In the silicon carbide single crystal growth apparatus 100 provided in this application embodiment, the gas in the sublimation chamber 11 enters the gas mixing chamber 12 from the first porous graphite plate 4. The first porous graphite plate 4 can guide and reshape the gas entering the gas mixing chamber 12 from the sublimation chamber 11. The first porous graphite plate 4 can also reduce the reflux of gas in the gas mixing chamber 12 back to the sublimation chamber 11. The second porous graphite plate 5 can generate flow equalization and damping effect on the passing gas flow, so that the vapor from the sublimation of polycrystalline powder O2 and the injected epitaxial gas are mixed and pressure equalized in the gas mixing chamber 12 to form a gas phase material with relatively uniform composition and pressure. The gas mixing chamber 12 forces the mixed gas phase material to pass uniformly through the second porous graphite plate 5, so that the gas phase material can be transported to the seed crystal growth interface of the crystallization chamber 13 in a nearly vertical, laminar flow manner, which can reduce the degree of airflow turbulence. Therefore, with the combined action of the first porous graphite plate 4 and the second porous graphite plate 5, the gas can be buffered in the gas mixing chamber 12, and the gas pressure can be balanced. This can reduce the probability of local component accumulation on the crystal growth surface and the degree of deviation of the carbon-silicon ratio from the ideal state, thereby reducing the probability of generating a large number of crystal defects such as impurities, microtubes and dislocations.

[0079] In some embodiments, the gas injection device 3 includes a first delivery pipe 31, a second delivery pipe 32, a third delivery pipe 33, and a manifold 34.

[0080] The manifold 34 is inserted through the crucible 1, and the first delivery pipe 31, the second delivery pipe 32 and the third delivery pipe 33 are all connected to the manifold 34.

[0081] It is understood that the first end of the manifold 34 can be located inside the gas mixing chamber 12, and the second end of the manifold 34 can be located outside the crucible. The first delivery pipe 31, the second delivery pipe 32 and the third delivery pipe 33 are all connected to the second end of the manifold 34.

[0082] The first conveying pipe 31 is used to convey the carbon source, the second conveying pipe 32 is used to convey the silicon source, and the third conveying pipe 33 is used to convey the auxiliary gas. The first conveying pipe 31, the second conveying pipe 32 and the third conveying pipe 33 are all connected in series with a flow regulating device 8.

[0083] The gas injection device 3 described above can adjust the flow rate of the silicon source, the flow rate of the carbon source, and the flow rate of the auxiliary gas, thereby controlling the flow rate, partial pressure, and Si / C ratio of various gases injected into the epitaxial gas. The gas injection device 3 can adjust the supersaturation and chemical environment at the growth interface independently of the temperature field, optimize the growth chemical environment, effectively suppress microtubes, reduce dislocation density (such as TSD (Threading Screw Dislocation) and BPD (Basal Plane Dislocation)), improve crystal quality, and also broaden the process window for better repeatability.

[0084] It should be noted that the process window refers to the adjustable range of various process parameters (such as temperature, pressure, gas flow rate, etc.) that can produce qualified crystals during a growth process; repeatability refers to the degree of consistency of the results obtained when the same process is run multiple times under exactly the same set conditions.

[0085] The flow regulating device 8 may include a flow regulating valve and a flow meter, or the flow regulating device 8 may have other structures, which are not limited in the embodiments of this application.

[0086] In other embodiments, the gas injection device 3 may also have other structures. For example, the gas injection device 3 may not include the manifold 34 and may include a first delivery pipe 31, a second delivery pipe 32 and a third delivery pipe 33. The first delivery pipe 31, the second delivery pipe 32 and the third delivery pipe 33 are all inserted through the crucible, and the outlets of the first delivery pipe 31, the second delivery pipe 32 and the third delivery pipe 33 are all located in the gas mixing chamber.

[0087] During growth, the growth material flow more easily reaches the radially central region of seed crystal 03 first, and then the radially edge region of seed crystal 03. It should be noted that radial direction is perpendicular to the first direction, which can be understood as the axial direction of seed crystal 03. This can lead to deformation of the growth interface. For example... Figure 1 As shown, to improve growth uniformity, the second porous graphite plate 5 is a curved plate, and the second porous graphite plate 5 protrudes towards the bottom end of the gas mixing chamber 12 along the first direction. Figure 3 and Figure 4 As shown, in order to optimize the function of the second porous graphite plate 5, the second porous graphite plate 5 can be a spherical crown plate.

[0088] In the above embodiments, the second porous graphite plate 5 controls the transport of material flow. The radius of curvature of the second porous graphite plate 5 controls the transport of crystal growth components, balancing the component transport in the middle and edge regions of the seed crystal 03. The radius of curvature of the second porous graphite plate 5 can physically define the initial growth interface shape, actively compensate for the growth interface deformation caused by the thermal field, and make the actual growth interface closer to the ideal state, thereby significantly reducing thermal stress and dislocation proliferation caused by poor interface shape. It can control the convexity of the single crystal 01, effectively reduce the internal pressure of the single crystal 01, and reduce the probability and degree of crystal cracking, thereby improving the crystal yield.

[0089] In some embodiments, the radius of curvature of the second porous graphite plate 5 can be 50cm-500cm. For example, the radius of curvature of the second porous graphite plate is 50cm, 100cm or 500cm.

[0090] In some other embodiments, the radius of curvature of the second porous graphite plate 5 may also be other values, and this application embodiment does not limit this.

[0091] During the operation of the silicon carbide single crystal growth apparatus 100, the sublimation chamber 11, the gas mixing chamber 12, and the crystallization chamber 13 have different temperature requirements. To facilitate individual temperature control of the sublimation chamber 11, the gas mixing chamber 12, and the crystallization chamber 13, the heating device 2 includes a first heater 21, a second heater 22, and a third heater 23. Any two of the first heater 21, the second heater 22, and the third heater 23 are independent of each other. The first heater 21 is used to heat the sublimation chamber 11, the second heater 22 is used to heat the gas mixing chamber 12, and the third heater 23 is used to heat the crystallization chamber 13.

[0092] In the above embodiments, the heating device 2 can heat in zones, which can more accurately control the temperature and temperature gradient at the growth interface and promote the improvement of crystal quality; the accurate control of the temperature gradient from polycrystalline powder 02 to seed crystal 03 can effectively control the crystal growth rate.

[0093] The first heater 21, the second heater 22, and the third heater 23 can all be graphite heaters or other types.

[0094] To facilitate the installation of the first heater 21 and increase the heating area, the first heater 21 includes a lower heater 211 and a first side heater 212. The lower heater 211 is located at the bottom of the sublimation chamber 11, and the first side heater 212 surrounds the periphery of the sublimation chamber 11. In this way, the first heater 21 makes the temperature in the polycrystalline powder 02 more uniform, improves the sublimation uniformity of the polycrystalline powder 02, enhances the controllability of the sublimation of the gas phase components, improves the stability of crystal growth, and also improves the overall utilization efficiency of the powder.

[0095] It should be noted that the end of the sublimation chamber 11 furthest from the gas mixing chamber 12 along the first direction is the bottom end. The lower heater 211 is located at the bottom end of the crucible 1 along the first direction, and the first side heater 212 surrounds the periphery of the crucible 1.

[0096] To facilitate the placement of the second heater 22, the second heater 22 is arranged around the periphery of the gas mixing chamber 12. It can be understood that the second heater 22 is arranged around the periphery of the crucible 1.

[0097] To facilitate the installation of the third heater 23 and increase the heating area, the third heater 23 includes an upper heater 231 and a third side heater 232. The upper heater 231 is located at the top of the crystallization cavity 13, and the third side heater 232 surrounds the periphery of the crystallization cavity 13.

[0098] It should be noted that the end of the crystallization chamber 13 furthest from the gas mixing chamber 12 along the first direction is the top. The upper heater 231 is located at the top of the crucible 1 along the first direction, and the third side heater 232 surrounds the periphery of the crucible 1.

[0099] The above-described structures of the first heater 21, the second heater 22, and the third heater 23 can be implemented individually or in any combination, and the embodiments of this application do not limit this.

[0100] When the above-described structural combination of the first heater 21, the second heater 22, and the third heater 23 is implemented, the first side heater 212, the second heater 22, and the third side heater 232 are distributed along the first direction.

[0101] In other embodiments, the first heater 21, the second heater 22, and the third heater 23 may have other structures, which are not limited in this application.

[0102] In some embodiments, the silicon carbide single crystal growth apparatus 100 further includes a flow guide ring 6 disposed in the sublimation chamber 11. The outer wall of the flow guide ring 6 is in contact with the inner wall of the sublimation chamber 11, and the inner flow guide cavity 61 of the flow guide ring 6 gradually narrows along a first direction, with the larger end and the smaller end of the inner flow guide cavity 61 close to the bottom end of the sublimation chamber 11. In this way, the flow guide ring 6 can guide the gas phase components from the lower raw material sublimation zone, so that the gas phase components enter the gas mixing chamber 12 more uniformly and smoothly. Moreover, under the combined action of the flow guide ring 6, the first porous graphite plate 4, and the second porous graphite plate 5, the gas phase components flow more uniformly and smoothly through the gas mixing chamber 12 to the seed crystal growth interface, which can suppress turbulence and local eddies, provide a stable material flow for the growth interface, reduce defects caused by excessively high or low local supersaturation, and even avoid defects caused by excessively high or low local supersaturation.

[0103] It should be noted that the first direction can be the axial direction of the guide ring 6.

[0104] like Figure 2 As shown, in order to improve the flow guiding effect of the flow guiding ring 6, the taper θ of the flow guiding inner cavity 61 can be 30°-60°. For example, the taper θ of the flow guiding inner cavity 61 can be 40°.

[0105] The taper θ of the inner cavity 61 can also be other values, and this application embodiment does not limit this.

[0106] In some embodiments, such as Figure 1 As shown, the sublimation chamber 11 includes a first sublimation chamber portion 111 and a second sublimation chamber portion 112, which are connected. The cross-sectional area of ​​the first sublimation chamber portion 111 is larger than that of the second sublimation chamber portion 112. The cross-sections of both the first and second sublimation chamber portions 111 and 112 are perpendicular to the first direction. The flow guide ring 6 is disposed at the top end of the first sublimation chamber portion 111 along the first direction.

[0107] It should be noted that the top end of the first part 111 of the sublimation cavity along the first direction is connected to the second part 112 of the sublimation cavity. The smaller end and the larger end of the guide cavity 61 are close to the second part 112 of the sublimation cavity.

[0108] To reduce the impact of the current guiding ring 6 on the growth of single crystal 01, the current guiding ring 6 can be a graphite component. In this embodiment, the current guiding ring 6 and the crucible 1 can be an integral structure or a separate structure.

[0109] The silicon carbide single crystal growth apparatus 100 provided in this application embodiment, through the combined effects of a synergistic growth mechanism, zoned heating, and flow guiding ring 6, ensures uniform and stable gas phase composition, partial pressure, and mass flow rate at the growth interface. This improves the utilization rate of polycrystalline powder O2 and increases the crystal growth thickness, for example, from approximately 10 mm to approximately 30 mm. It also reduces defects (such as dislocations and inclusions) caused by uneven transport, allowing the crystal to grow stably at a higher average supersaturation, thus increasing the crystal growth rate and suppressing harmful side reactions. Therefore, the aforementioned silicon carbide single crystal growth apparatus 100, based on the PVT method, introduces the high growth rate and continuous supply capability of the HTCCVD method, and incorporates the flow guiding ring 6, the first porous graphite plate 4, the second porous graphite plate 5, and the flow regulating device 8 to achieve precise and active control of the gas composition, partial pressure, and flow direction within the growth chamber. This maintains the high crystal quality advantage of the PVT method while achieving stable growth of high-speed, low-defect, and large-thickness single crystal O1.

[0110] Based on the silicon carbide single crystal growth apparatus 100 provided in the above embodiments, this application also provides a silicon carbide single crystal growth furnace. For example... Figure 5As shown, the silicon carbide single crystal growth furnace provided in this application embodiment includes: furnace body 200 and silicon carbide single crystal growth device 100 as described in the above embodiment. The furnace body 200 has a growth chamber 201, and the silicon carbide single crystal growth device 100 is located in the growth chamber 201.

[0111] In the silicon carbide single crystal growth furnace, the inlet of the gas injection device 3 is located outside the furnace body 200. For example, the first conveying pipe 31, the second conveying pipe 32 and the third conveying pipe 33 in the gas injection device 3 are all installed through the furnace body 200, and the inlets of the first conveying pipe 31, the second conveying pipe 32 and the third conveying pipe 33 are all located outside the furnace body 200.

[0112] In some embodiments, to simplify the internal structure of the furnace body 200, the first conveying pipe 31, the second conveying pipe 32, and the third conveying pipe 33 may all be located outside the furnace body 200. Correspondingly, the connection points between the first conveying pipe 31 and the manifold 34, the second conveying pipe 32 and the manifold 34, and the third conveying pipe 33 and the manifold 34 may all be located outside the furnace body 200. It is understood that the manifold 34 passes through the furnace body 200, with a portion of the manifold 34 located inside the furnace body 200.

[0113] In some other embodiments, the connection positions of the first conveying pipe 31 and the manifold 34, the connection positions of the second conveying pipe 32 and the manifold 34, and the connection positions of the third conveying pipe 33 and the manifold 34 may all be located inside the furnace body 200, and are not limited to the above embodiments.

[0114] Since the silicon carbide single crystal growth apparatus 100 provided in the above embodiments has the above-mentioned technical effects, and the silicon carbide single crystal growth furnace includes the silicon carbide single crystal growth apparatus 100, the silicon carbide single crystal growth furnace also has the corresponding technical effects, which will not be elaborated here.

[0115] Based on the silicon carbide single crystal growth furnace provided in the above embodiments, this application also provides a silicon carbide single crystal growth method. This silicon carbide single crystal growth method uses a silicon carbide single crystal growth furnace to grow silicon carbide single crystals. The silicon carbide single crystal growth method includes:

[0116] S1: Load polycrystalline powder 02 into the sublimation chamber 11 of crucible 1, and fix seed crystal 03 at the top of crystallization chamber 13 of crucible 1.

[0117] S2: Evacuate the growth chamber 201;

[0118] S3: Inject protective gas into the growth chamber 201;

[0119] S4: Start heating device 2 until the temperature of crystallization chamber 13 is 2000℃-2400℃ and the temperature of sublimation chamber 11 is 2000℃-2400℃, and the temperature of sublimation chamber 11 is greater than the temperature of crystallization chamber 13.

[0120] S5: Epitaxial gas is injected into the gas mixing chamber 12 of crucible 1 through gas injection device 3. The epitaxial gas includes silicon source, carbon source and auxiliary gas to achieve mixed growth.

[0121] In S1 above, polycrystalline powder 02 is silicon carbide polycrystalline powder, and seed crystal 03 is silicon carbide seed crystal. For example, seed crystal 03 can be a 4H-SiC seed crystal.

[0122] In S2 above, the crucible 1 can be evacuated using a vacuum pump via the gas injection device 3, for example, by evacuating the crucible 1 to a vacuum level of 10. -3 Pa.

[0123] In step S3 above, the protective gas can be argon. The protective gas is introduced into crucible 1 until the pressure inside crucible 1 reaches a first preset pressure, for example, 5 kPa.

[0124] In S4 above, starting the heating device 2 can specifically involve starting the first heater 21, the second heater 22, and the third heater 23. For example, the temperature of the crystallization chamber 13 can be 2100-2200℃, and the temperature of the sublimation chamber 11 can be 2250-2350℃.

[0125] It should be noted that S5 is entered when the temperature in the sublimation chamber 11 and the crystallization chamber 13 is stable.

[0126] The temperature within the sublimation chamber 11 is stable, which can be understood as the temperature change within the sublimation chamber 11 per unit time falling within a first set temperature range. Similarly, the temperature within the crystallization chamber 13 is stable, which can be understood as the temperature change within the crystallization chamber 13 per unit time falling within a second set temperature range.

[0127] The specific ranges of the first and second set temperature ranges can be selected according to the actual situation, and this application embodiment does not limit them.

[0128] In the above S5, the flow rate of the silicon source is 50 sccm-200 sccm, the atomic ratio of Si / C is 0.5-2, the flow rate of the auxiliary gas is 100 sccm-5000 sccm, and the pressure in the gas mixing chamber 12 is 1 kPa-20 kPa.

[0129] For example, the silicon source may include silane, with a flow rate of 50 sccm-200 sccm.

[0130] In some other embodiments, the flow rate of the silicon source may be other values, the atomic ratio of Si / C may be other values, the flow rate of the auxiliary gas may be other values, and the pressure in the gas mixing chamber 12 may be other values.

[0131] It should be noted that all the flow rates mentioned above are volumetric flow rates. The flow rate of the carbon source is determined based on the Si / C atomic ratio.

[0132] In the above-mentioned silicon carbide single crystal growth method, continuous growth can be achieved for 140 hours under the conditions defined in S5.

[0133] Compared with the PVT method, the above-described silicon carbide single crystal growth method can increase the average crystal growth rate to 0.2 mm / h-0.3 mm / h, and the final thickness of single crystal 01 can reach 30 mm (the thickness of single crystal obtained by the PVT method is 12 mm-15 mm). Tests show that the single crystal 01 obtained by the above-described silicon carbide single crystal growth method has a microtube density reduced by more than an order of magnitude, a decrease in dislocation density, and a significant improvement in crystal color uniformity.

[0134] Since the aforementioned silicon carbide single crystal growth furnace has the above-mentioned technical effects, and the aforementioned silicon carbide single crystal growth method uses the aforementioned silicon carbide single crystal growth furnace to grow silicon carbide single crystals, the aforementioned silicon carbide single crystal growth method also has corresponding other technical effects, which will not be elaborated here.

[0135] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A silicon carbide single crystal growth apparatus, characterized in that, include: A crucible (1) having a sublimation chamber (11), a gas mixing chamber (12), and a crystallization chamber (13), wherein the sublimation chamber (11), the gas mixing chamber (12), and the crystallization chamber (13) are distributed and connected along a first direction; Heating device (2) is disposed in the crucible (1) and is used to heat the sublimation chamber (11), the gas mixing chamber (12) and the crystallization chamber (13). Gas injection device (3), the gas injection device (3) is used to inject epitaxial gas into the gas mixing chamber (12), the epitaxial gas includes silicon source, carbon source and auxiliary gas; A first porous graphite plate (4) and a second porous graphite plate (5), wherein the first porous graphite plate (4) is disposed at the bottom end of the gas mixing chamber (12) near the sublimation chamber (11), and the second porous graphite plate (5) is disposed at the top end of the gas mixing chamber (12) near the crystallization chamber (13).

2. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that, The second porous graphite plate (5) is a curved plate, and the second porous graphite plate (5) protrudes outwards towards the bottom end of the gas mixing chamber (12) along the first direction.

3. The silicon carbide single crystal growth apparatus according to claim 2, characterized in that, The radius of curvature of the second porous graphite plate (5) is 50cm-500cm.

4. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that, The porosity of the first porous graphite plate (4) is 30%-80%, and the thickness of the first porous graphite plate (4) is 1mm-10mm; And / or, the porosity of the second porous graphite plate (5) is 30%-80%, and the thickness of the second porous graphite plate (5) is 0.5mm-2mm.

5. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that, The heating device (2) includes a first heater (21), a second heater (22) and a third heater (23). Any two of the first heater (21), the second heater (22) and the third heater (23) are independent of each other. The first heater (21) is used to heat the sublimation chamber (11), the second heater (22) is used to heat the gas mixing chamber (12), and the third heater (23) is used to heat the crystallization chamber (13).

6. The silicon carbide single crystal growth apparatus according to claim 5, characterized in that, The first heater (21) includes a lower heater (211) and a first side heater (212). The lower heater (211) is located at the bottom end of the sublimation chamber (11), and the first side heater (212) surrounds the periphery of the sublimation chamber (11). And / or, the second heater (22) surrounds the periphery of the gas mixing chamber (12); And / or, the third heater (23) includes an upper heater (231) and a third side heater (232), the upper heater (231) being located at the top of the crystallization chamber (13) and the third side heater (232) surrounding the periphery of the crystallization chamber (13); And / or, the first heater (21), the second heater (22) and the third heater (23) are all graphite heaters.

7. The silicon carbide single crystal growth apparatus according to claim 1, characterized in that, The gas injection device (3) includes: a manifold (34) passing through the crucible (1), and a first delivery pipe (31), a second delivery pipe (32) and a third delivery pipe (33) all connected to the manifold (34). The first conveying pipe (31) is used to convey the carbon source, the second conveying pipe (32) is used to convey the silicon source, and the third conveying pipe (33) is used to convey the auxiliary gas. The first conveying pipe (31), the second conveying pipe (32) and the third conveying pipe (33) are all connected in series with a flow regulating device (8).

8. The silicon carbide single crystal growth apparatus according to any one of claims 1-7, characterized in that, The silicon carbide single crystal growth apparatus further includes a flow guide ring (6), which is disposed in the sublimation cavity (11). The outer wall of the flow guide ring (6) is attached to the inner wall of the sublimation cavity (11). The flow guide inner cavity (61) of the flow guide ring (6) gradually narrows along the first direction, and the larger end and the smaller end of the flow guide inner cavity (61) are close to the bottom end of the sublimation cavity (11).

9. A silicon carbide single crystal growth furnace, characterized in that, include: The furnace body (200) and the silicon carbide single crystal growth apparatus (100) as described in any one of claims 1-8, wherein the furnace body (200) has a growth chamber (201) and the silicon carbide single crystal growth apparatus (100) is located in the growth chamber (201).

10. A method for growing silicon carbide single crystals, characterized in that, The silicon carbide single crystal growth method uses the silicon carbide single crystal growth furnace as described in claim 9 to grow silicon carbide single crystals, and the silicon carbide single crystal growth method includes: Polycrystalline powder (02) is loaded into the sublimation chamber (11) of the crucible (1), and seed crystal (03) is fixed at the top of the crystallization chamber (13) of the crucible (1); Evacuate the growth chamber (201); A protective gas is introduced into the growth chamber (201); Start the heating device (2) until the temperature of the crystallization chamber (13) is 2000℃-2400℃ and the temperature of the sublimation chamber (11) is 2000℃-2400℃, and the temperature of the sublimation chamber (11) is greater than the temperature of the crystallization chamber (13); Epitaxial gas is injected into the gas mixing chamber (12) of the crucible (1) through the gas injection device (3). The epitaxial gas includes silicon source, carbon source and auxiliary gas to achieve mixed growth.

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