Silicon carbide single crystal growth apparatus and method of operation thereof

Abstract

The application belongs to the field of silicon carbide single crystal growth, and particularly relates to high-temperature solution method silicon carbide crystal growth, and especially relates to a silicon carbide single crystal growth device and a working method thereof. The silicon carbide single crystal growth device comprises a graphite crucible, a heating assembly, a driving mechanism, a seed crystal lifting assembly and a graphite flow guide plate. The graphite flow guide plate is arranged above the graphite crucible, and a lifting rod of the seed crystal lifting assembly penetrates through the graphite flow guide plate. During seed crystal growth, the graphite flow guide plate is in communication with an external inert gas source, and is used for continuously introducing inert gas into the seed crystal lifting assembly to dissipate heat from the seed crystal adhered to the bottom of the seed crystal lifting assembly. By introducing the flowing inert gas into the seed crystal lifting assembly, the seed crystal at the bottom of the seed crystal lifting assembly is continuously dissipated, so that the temperature gradient between the seed crystal and the solid-liquid interface is increased, and the growth driving force is improved to realize rapid crystal growth.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide single crystal growth, specifically relating to silicon carbide crystal growth by high-temperature solution method, and particularly to a silicon carbide single crystal growth apparatus and its working method. Background Technology

[0002] Silicon carbide (SiC), as a representative of third-generation semiconductor materials, has been widely used in new energy vehicles, 5G communications, smart grids and other fields due to its excellent properties such as wide bandgap, high breakdown field strength and high thermal conductivity.

[0003] Currently, the mainstream method for preparing silicon carbide single crystals is the physical vapor transport (PVT) method. However, this method suffers from problems such as low growth rate, numerous crystal defects, and high cost. The liquid phase method, as an alternative technology, has advantages such as low growth temperature, stable environment, and high crystal quality, but it still faces the following technical bottlenecks:

[0004] The internal temperature difference of the solution and the temperature gradient at the solid-liquid interface are difficult to control. At different stages of crystal growth, it is necessary to adjust the internal temperature of the solution and the temperature gradient at the solid-liquid interface in a timely manner. The heaters in related technologies can only adjust the thermal field at a certain moment and cannot meet the growth requirements of the entire crystal growth stage.

[0005] Growth rate is limited: In order to avoid crystallization on the liquid surface from affecting the normal growth of silicon carbide, the internal temperature difference of the solution and the temperature gradient at the solid-liquid interface cannot be further increased, the growth driving force is limited, and the growth rate is restricted.

[0006] Therefore, how to improve the growth rate of silicon carbide crystals is a technical problem that urgently needs to be solved.

[0007] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0008] This disclosure provides at least one silicon carbide single crystal growth apparatus and its operating method.

[0009] In a first aspect, embodiments of this disclosure provide a silicon carbide single crystal growth apparatus, comprising:

[0010] Graphite crucible, used to hold raw materials;

[0011] A heating assembly is disposed around and on top of the graphite crucible and is used to heat the graphite crucible;

[0012] A drive mechanism is disposed below the graphite crucible and is used to drive the graphite crucible to rotate.

[0013] A seed crystal pulling assembly is disposed above the graphite crucible and is used for crystal growth;

[0014] A graphite guide plate is disposed above the graphite crucible, and the lifting rod of the seed crystal lifting assembly passes through the graphite guide plate;

[0015] During seed crystal growth, the graphite guide plate is connected to an external inert gas source and is used to continuously introduce inert gas into the seed crystal lifting assembly to dissipate heat from the seed crystal bonded to the bottom of the seed crystal lifting assembly.

[0016] In one alternative embodiment, the graphite guide plate includes:

[0017] The plate body has a through hole in its middle for the lifting rod to pass through;

[0018] Furthermore, an airflow ring extends downward along the perforation of the plate body;

[0019] The plate body has multiple air channels that communicate with the perforations along the radial direction, so as to introduce inert gas from an external inert gas source into the airflow ring to dissipate heat from the seed crystal bonded to the bottom of the seed crystal pulling assembly.

[0020] In one optional embodiment, the seed crystal pulling assembly further includes:

[0021] A rotating head is disposed at the bottom of the lifting rod, and the bottom surface of the rotating head is used for bonding the seed crystal;

[0022] Wherein, the diameter of the airflow ring is R1;

[0023] The diameter of the rotating head is R2;

[0024] Where R2 is greater than R1, and the units of R2 and R1 are mm.

[0025] In one alternative embodiment, a protective ring extends upward from the top surface of the rotating head along its edge.

[0026] The airflow ring is inserted into the protective ring;

[0027] Furthermore, a gap is provided between the airflow ring and the protective ring to allow the inert gas introduced into the seed crystal pulling assembly to be discharged through the gap.

[0028] In one alternative embodiment, the lower end of the airflow ring is trumpet-shaped;

[0029] The upper end of the protective ring is tapered;

[0030] The lower end of the airflow ring is positioned opposite the upper end of the protective ring to gather and discharge the inert gas entering the seed crystal pulling assembly, thereby reducing fluctuations in the molten liquid inside the graphite crucible.

[0031] In one alternative implementation, the heating assembly includes:

[0032] A main heater, which is disposed around the side wall of the graphite crucible, is used to heat the graphite crucible.

[0033] An auxiliary heater is disposed at the top of the graphite crucible and is used to keep the upper part of the graphite crucible warm.

[0034] In one optional implementation, the drive mechanism includes:

[0035] Pallet support;

[0036] A drive shaft is located at the bottom of the support tray and is driven by an external drive motor.

[0037] In one alternative embodiment, the silicon carbide single crystal growth apparatus further includes a furnace body (600).

[0038] The graphite crucible, heating assembly, and seed crystal pulling assembly are disposed inside the furnace body, and the pulling rod of the seed crystal pulling assembly extends from the top of the furnace body.

[0039] Secondly, this disclosure also provides a method of operation for a silicon carbide single crystal growth apparatus as described above, the method comprising:

[0040] Step S1: Place the raw materials and flux into a graphite crucible and heat it to a preset temperature using a heating element to completely melt the raw materials.

[0041] Step S2: The seed crystal lifting assembly lowers the seed crystal above the molten liquid, and the heating assembly is turned on;

[0042] Step S3: The seed crystal lifting assembly lowers the seed crystal until it contacts the surface of the molten liquid;

[0043] In step S4, the lifting rod drives the seed crystal to start rotating and lifting. At the same time, the external inert gas source dissipates heat from the seed crystal bonded to the bottom of the seed crystal lifting assembly through the graphite guide plate, and the crystal begins to grow.

[0044] In one alternative implementation, the heating assembly includes:

[0045] A main heater, which is disposed around the side wall of the graphite crucible, is used to heat the graphite crucible.

[0046] An auxiliary heater is disposed at the top of the graphite crucible and is used to keep the upper part of the graphite crucible warm.

[0047] Step S4 also includes:

[0048] The auxiliary heater adjusts the heat preservation power during crystal growth, and the inert gas source adjusts the inert gas intake during crystal growth.

[0049] The heat preservation power gradually decreases as the crystal growth time increases;

[0050] The amount of inert gas introduced gradually decreases as the crystal growth time increases.

[0051] The beneficial effect of this invention is that the silicon carbide single crystal growth apparatus and its working method continuously dissipate heat to the seed crystal at the bottom of the seed crystal pulling assembly by introducing flowing inert gas into the seed crystal pulling assembly, thereby increasing the temperature gradient between the seed crystal and the solid-liquid interface, thereby improving the growth driving force and achieving rapid crystal growth.

[0052] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0054] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0055] Figure 1 This is a half-sectional view of the silicon carbide single crystal growth apparatus provided in an embodiment of this disclosure;

[0056] Figure 2 A schematic diagram of a portion of the structure of the silicon carbide single crystal growth apparatus provided in an embodiment of this disclosure;

[0057] Figure 3 A cross-sectional view of a silicon carbide single crystal growth apparatus provided in an embodiment of this disclosure;

[0058] Figure 4Electrical control schematic diagram of the silicon carbide single crystal growth apparatus provided in the embodiments of this disclosure;

[0059] Figure 5 A flowchart illustrating the operation method of the silicon carbide single crystal growth apparatus provided in this embodiment of the disclosure.

[0060] In the diagram: 100, graphite crucible; 200, heating assembly; 210, main heater; 220, auxiliary heater; 300, drive mechanism; 400, seed crystal lifting assembly; 410, lifting rod; 420, rotating head; 421, protective ring; 500, graphite guide plate; 510, plate body; 520, perforation; 530, airflow ring; 540, air passage; 600, furnace body; 700, seed crystal. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] In this document, when it is mentioned that a first component is located on a second component, this can mean that the first component can be directly formed on the second component, or that a third component can be inserted between the first and second components. Furthermore, in the accompanying drawings, the thickness of the components may be exaggerated or reduced for the purpose of effectively describing the technical content.

[0063] In this document, when an element or layer is referred to as “located,” “joined to,” “connected to,” “attached to,” or “coupled to” another element or layer, it may be directly located, joined, connected, attached to, or coupled to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as “directly on another element or layer,” “directly joined to,” “directly connected to,” “directly attached to,” or “directly coupled to” another element or layer, there may be no intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0064] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise expressly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0065] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0066] Research has revealed that the liquid-phase method, as an alternative technology for silicon carbide single crystal preparation, has advantages such as low growth temperature, stable environment, and high crystal quality. However, it still faces the following technical bottlenecks: The internal temperature difference and solid-liquid interface temperature gradient are difficult to control. At different stages of crystal growth, timely adjustments to the internal temperature and solid-liquid interface temperature gradient are necessary. The heaters in related technologies can only adjust the thermal field at a specific moment, failing to meet the requirements for long-term growth. Crystallization easily occurs on the surface of the molten liquid and at the edge of the crucible. The thermal field in related technologies cannot avoid increasing the internal temperature difference of the solution, leading to a large amount of crystallization on the liquid surface and at the edge of the crucible during rapid crystal growth, affecting stable crystal growth. Growth rate is limited: To avoid surface crystallization affecting the normal growth of silicon carbide, the internal temperature difference and solid-liquid interface temperature gradient cannot be further increased, limiting the growth driving force and restricting the growth rate.

[0067] Based on the above research, this disclosure provides a silicon carbide single crystal growth apparatus and its working method. By introducing flowing inert gas into the seed crystal pulling assembly 400, heat is continuously dissipated from the seed crystal 700 at the bottom of the seed crystal pulling assembly 400, thereby increasing the temperature gradient between the seed crystal 700 and the solid-liquid interface, thereby improving the growth driving force and achieving rapid crystal growth.

[0068] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure should be considered as the inventor's contribution to this disclosure.

[0069] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0070] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0071] Please see Figure 1 and Figure 2 At least one embodiment provides a silicon carbide single crystal growth apparatus, comprising: a graphite crucible 100 for holding raw materials; a heating assembly 200 disposed around and on top of the graphite crucible 100 for heating the graphite crucible 100; a driving mechanism 300 disposed below the graphite crucible 100 for rotating the graphite crucible 100; a seed crystal pulling assembly 400 disposed above the graphite crucible 100 for crystal growth; and a graphite guide plate 500 disposed above the graphite crucible 100, with the pulling rod 410 of the seed crystal pulling assembly 400 passing through the graphite guide plate 500; during seed crystal growth, the graphite guide plate 500 is connected to an external inert gas source and is used to continuously introduce inert gas into the seed crystal pulling assembly 400 to dissipate heat from the seed crystal 700 adhered to the bottom of the seed crystal pulling assembly 400.

[0072] By introducing flowing inert gas into the seed crystal pulling assembly 400, heat is continuously dissipated from the seed crystal 700 at the bottom of the seed crystal pulling assembly 400, thereby increasing the temperature gradient between the seed crystal 700 and the solid-liquid interface, thus improving the growth driving force and achieving rapid crystal growth.

[0073] It should be noted that the silicon carbide single crystal growth device is located inside the furnace body 600.

[0074] Please see Figure 2 and Figure 3The graphite guide plate 500 includes: a plate body 510, in which a through hole 520 is provided for the lifting rod 410 to pass through; and an airflow ring 530 extends downward from the plate body 510 along the through hole 520; the plate body 510 is provided radially with a plurality of air passages 540 communicating with the through hole 520, so as to introduce inert gas from an external inert gas source into the airflow ring 530 to dissipate heat from the seed crystal 700 bonded to the bottom of the seed crystal lifting assembly 400.

[0075] Specifically, the number of air channels 540 is between 16 and 24. Through the radially distributed multiple air channels 540, the inert gas can uniformly dissipate heat from the seed crystal 700, thereby avoiding macroscopic steps in crystal growth caused by uneven local heat dissipation. At the same time, the airflow ring 530 guides the inert gas, thereby improving the heat dissipation effect on the seed crystal 700.

[0076] Please continue reading. Figure 2 and Figure 3 The seed crystal lifting assembly 400 further includes a rotating head 420, which is disposed at the bottom of the lifting rod 410, and the bottom surface of the rotating head 420 is used for bonding the seed crystal 700; wherein, the diameter of the airflow ring 530 is R1; the diameter of the rotating head 420 is R2; wherein, R2 is greater than R1, and the units of R2 and R1 are mm.

[0077] By limiting the diameter R2 of the rotating head 420 and the diameter R1 of the airflow ring 530, it is ensured that the inert gas completely covers the bonding surface of the seed crystal 700. That is, the diameter R1 of the airflow ring 530 is larger than the diameter of the seed crystal 700, thereby avoiding insufficient heat dissipation at the edge of the seed crystal 700.

[0078] Please continue reading. Figure 2 and Figure 3 A protective ring 421 extends upward from the top surface of the rotating head 420 along its edge; the airflow ring 530 is inserted into the protective ring 421; and a gap is provided between the airflow ring 530 and the protective ring 421 to allow the inert gas introduced into the seed crystal lifting assembly 400 to be discharged from the gap.

[0079] The airflow ring 530 is inserted into the protective ring 421 to form a gap, forcing the inert gas to exit along a fixed path (e.g., Figure 3 As shown in Figure F, this avoids airflow disturbance of the molten liquid's surface, ensuring the stability of crystal growth.

[0080] It should be noted that the lower end of the airflow ring 530 is trumpet-shaped; the upper end of the protective ring 421 is constricted; wherein, the lower end of the airflow ring 530 and the upper end of the protective ring 421 are arranged opposite to each other to gather and discharge the inert gas entering the seed crystal pulling assembly 400, thereby reducing the fluctuation of the molten liquid in the graphite crucible 100.

[0081] Please see Figure 1 and Figure 3 The heating assembly 200 includes: a main heater 210, which is disposed around the side wall of the graphite crucible 100 and is used to heat the graphite crucible 100; and an auxiliary heater 220, which is disposed on the top of the graphite crucible 100 and is used to keep the upper part of the graphite crucible 100 warm.

[0082] The upper part of the graphite crucible 100 is kept warm by the auxiliary heater 220, so that the excessive surface temperature of the molten liquid causes crystallization on the surface of the molten liquid, reducing the impact on crystal growth.

[0083] Please see Figure 1 The driving mechanism includes: a support tray; a drive shaft disposed at the bottom of the support tray, and the drive shaft is driven by an external drive motor.

[0084] Please continue reading. Figure 1 The silicon carbide single crystal growth apparatus further includes a furnace body 600; the graphite crucible 100, the heating component 200 and the seed crystal pulling component 400 are disposed in the furnace body, and the pulling rod of the seed crystal pulling component 400 extends from the top of the furnace body 600.

[0085] Please see Figure 4 The silicon carbide single crystal growth apparatus further includes a control module: the control module is configured to control the auxiliary heater 220 to adjust the heat preservation power during the crystal growth process, and to adjust the inert gas intake during the crystal growth process.

[0086] In a preferred embodiment, the heat preservation power gradually decreases as the crystal growth time increases; the inert gas intake gradually decreases as the crystal growth time increases.

[0087] Please see Figure 5 This disclosure also discloses a working method for the silicon carbide single crystal growth apparatus as described above. By introducing a flowing inert gas into the seed crystal pulling assembly 400, heat is continuously dissipated from the seed crystal 700 at the bottom of the seed crystal pulling assembly 400, thereby increasing the temperature gradient between the seed crystal 700 and the solid-liquid interface, thereby improving the growth driving force and achieving rapid crystal growth.

[0088] The working method includes:

[0089] Step S1: Place the raw materials and flux into the graphite crucible 100 and heat it to the preset temperature through the heating component 200 to completely melt the raw materials;

[0090] In step S2, the seed crystal lifting assembly 400 lowers the seed crystal 700 above the molten liquid, and the heating assembly 200 keeps the upper part of the graphite crucible 100 warm for a preset time.

[0091] Step S3: The seed crystal lifting assembly 400 lowers the seed crystal 700 until it contacts the surface of the molten liquid;

[0092] In step S4, the lifting rod 410 drives the seed crystal 700 to start rotating and lifting. At the same time, the external inert gas source dissipates heat from the seed crystal 700, which is attached to the bottom of the seed crystal lifting assembly 400, through the graphite guide plate 500, and the crystal begins to grow.

[0093] The heating assembly 200 includes: a main heater 210, which is disposed around the side wall of the graphite crucible 100 and is used to heat the graphite crucible 100; and an auxiliary heater 220, which is disposed on the top of the graphite crucible 100 and is used to keep the upper part of the graphite crucible 100 warm.

[0094] Step S4 also includes:

[0095] The auxiliary heater 220 adjusts the heat preservation power during crystal growth, and the inert gas source adjusts the inert gas intake during crystal growth.

[0096] The heat preservation power gradually decreases as the crystal growth time increases; the inert gas intake gradually decreases as the crystal growth time increases.

[0097] In Example 1, the silicon carbide single crystal growth apparatus was assembled as described above, and crystal growth was performed according to the following process:

[0098] Step 1: Close the furnace chamber and perform a vacuum process, then fill the furnace chamber with inert gas. Place the solvent raw materials Si, Cr, and Al into a graphite crucible 100 and heat to 1800℃ to melt them.

[0099] Step 2: After the raw material is completely melted, slowly lower the seed crystal rod 700 until it stops 5mm above the liquid surface. Then turn on the auxiliary heater 220 and stabilize for the first preset time.

[0100] Step 3: Slowly lower the seed crystal 700 to contact the liquid surface and stabilize for the second preset time.

[0101] Step 4: Under the drive of external force, the lifting rod 410 begins to rotate and lift, while inert gas (argon gas at 3L / min) is supplied to the graphite guide plate 500, and crystal growth begins.

[0102] In step S5, as the crystal grows, the power of the low auxiliary heater 220 is slowly reduced, and the flow rate of the inert gas is kept constant until the crystal growth is completed.

[0103] The 6-inch silicon carbide single crystal obtained in Example 1 has a smooth surface without obvious macroscopic steps or solvent inclusions, and no diameter reduction phenomenon. Compared with conventional hot field crystal growth, the crystal growth rate in this furnace is stably increased to 0.2 mm / h, and the growth cycle reaches 80 hours. No crystallization occurs on the liquid surface throughout the entire growth process. Raman characterization shows that the crystal is a high-quality 4H / SiC single crystal.

[0104] In Example 2, the silicon carbide single crystal growth apparatus was assembled as described above, and crystal growth was performed according to the following process:

[0105] Example 2 follows the same steps as Example 1, except that in step 5, the flow rate of the inert gas is gradually reduced until the flow rate is 2 L / min until the crystal growth is complete.

[0106] The 6-inch silicon carbide single crystal obtained in Example 2 has a smooth surface without obvious macroscopic steps or solvent inclusions, and no diameter reduction phenomenon. Compared with Example 1, the gas flow rate is slowly reduced during the growth process to ensure that the solute in the solution always meets the crystal growth requirements and avoid solvent inclusions and grooves caused by insufficient carbon supply. Of course, the reduction of heat dissipation from the 700-bar seed crystal will lead to a decrease in crystal growth rate. The crystal growth rate of this furnace is reduced to 0.15 mm / h, and the growth cycle reaches 80 hours.

[0107] Comparative Example 1: Following the above method, the silicon carbide single crystal growth apparatus was assembled, and crystal growth was carried out according to the following process:

[0108] Step 1: Close the furnace chamber and perform a vacuum process, then fill the furnace chamber with inert gas. Place the solvent raw materials Si, Cr, and Al into a graphite crucible 100 and heat to 1800℃ to melt them.

[0109] Step 2: After the raw material is completely melted, slowly lower the seed crystal rod 700 until it stops 5mm above the liquid surface. Then turn on the auxiliary heater 220 and stabilize for the first preset time.

[0110] Step 3: Slowly lower the seed crystal 700 to contact the liquid surface and stabilize for the second preset time.

[0111] Step 4: Under the drive of external force, the lifting rod 410 begins to rotate and lift, and the crystal begins to grow.

[0112] Step S5: As the crystal grows, the power of the low auxiliary heater 220 is slowly reduced until the crystal growth is complete.

[0113] The 6-inch silicon carbide single crystal obtained in Comparative Example 1 had a smooth surface without obvious grooves or solvent encapsulation. Significant diameter reduction occurred in the later stages of growth, with a crystal growth rate as low as 0.1 mm / h and a growth cycle of 60 hours. This phenomenon indicates that with the dual-heater thermal field structure, the simultaneous heating of the solution by the main and auxiliary heaters 220 resulted in a very small internal temperature difference and a small concentration gradient at the growth interface. Consequently, the crystal growth lacked sufficient driving force, leading to a smooth crystal surface but an extremely slow growth rate, which could not meet industrialization requirements.

[0114] Comparative Example 2

[0115] The silicon carbide single crystal growth apparatus is assembled in the manner described above, and crystal growth is carried out according to the following process:

[0116] Step 1: Close the furnace chamber and perform a vacuum process, then fill the furnace chamber with inert gas. Place the solvent raw materials Si, Cr, and Al into a graphite crucible 100 and heat to 1800℃ to melt them.

[0117] Step 2: After the raw material is completely melted, slowly lower the seed crystal rod 700 until it stops 5mm above the liquid surface. Then turn on the auxiliary heater 220 and stabilize for the first preset time.

[0118] Step 3: Slowly lower the seed crystal 700 to contact the liquid surface and stabilize for the second preset time.

[0119] Step 4: Under the drive of external force, the lifting rod 410 begins to rotate and lift, while inert gas (argon gas at 3L / min) is supplied to the graphite guide plate 500, and crystal growth begins.

[0120] In step S5, as the crystal grows, the power of the low auxiliary heater 220 is slowly reduced and the air flow rate is maintained at 3L / min until the crystal growth is completed.

[0121] The 6-inch silicon carbide single crystal obtained in Comparative Example 2 had a rough surface with obvious local polycrystalline adhesion. Smooth areas showed distinct steps and a small amount of solvent encapsulation. The growth rate in the single crystal region was as low as 0.15 mm / h, and the growth cycle reached 60 hours. Throughout the growth process, a large amount of silicon carbide crystals appeared on the liquid surface. Compared to Example 2, this furnace, with its single heater and added gas ventilation and graphite rod heat dissipation, caused disturbance to the free liquid surface during growth. The rapid increase in internal temperature difference led to quick crystallization on the liquid surface. Since crystallization requires continuous solute consumption, the growth interface suffered from insufficient solute concentration, resulting in numerous inclusions and grooves. Simultaneously, the silicon carbide crystals formed on the liquid surface were easily adsorbed onto the crystal growth surface.

[0122] The beneficial effects of this invention are that it provides a silicon carbide single crystal growth apparatus and its operating method. The silicon carbide single crystal growth apparatus includes: a graphite crucible 100 for holding raw materials; a heating assembly 200 disposed around and on top of the graphite crucible 100 for heating the graphite crucible 100; a driving mechanism 300 disposed below the graphite crucible 100 for rotating the graphite crucible 100; and a seed crystal pulling assembly 400. A graphite guide plate 500 is positioned above the graphite crucible 100 and is used for crystal growth. The lifting rod 410 of the seed crystal lifting assembly 400 passes through the graphite guide plate 500. During seed crystal growth, the graphite guide plate 500 is connected to an external inert gas source and is used to continuously introduce inert gas into the seed crystal lifting assembly 400 to dissipate heat from the seed crystal 700 adhered to the bottom of the seed crystal lifting assembly 400. By continuously introducing flowing inert gas into the seed crystal lifting assembly 400 to dissipate heat from the seed crystal 700 at the bottom of the seed crystal lifting assembly 400, the temperature gradient between the seed crystal 700 and the solid-liquid interface is increased, thereby enhancing the growth driving force and achieving rapid crystal growth.

[0123] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0124] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence unless expressly indicated herein. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed above may be referred to as a second element, component, region, layer, or segment.

[0125] Spatially relative terms, such as “inside,” “outside,” “below,” “below,” “down,” “above,” “up,” etc., may be used herein to describe the relationship between one element or feature illustrated in the figures and another element or feature. In addition to the orientations depicted in the figures, spatially relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is flipped, an element described as “below” or “below” other elements or features would be oriented as “above” other elements or features. Thus, the example term “below” can cover both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0126] In the above discussion, unless otherwise stated, when used to describe numerical values, the terms “about,” “approximately,” “basically,” etc., indicate a change of + / - 10% in that value.

[0127] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A silicon carbide single crystal growth apparatus, characterized in that, include: A graphite crucible (100) is used to hold raw materials; A heating assembly (200) is disposed around and on top of the graphite crucible (100) and is used to heat the graphite crucible (100); A drive mechanism (300) is disposed below the graphite crucible (100) and is used to drive the graphite crucible (100) to rotate; A seed crystal pulling assembly (400) is disposed above the graphite crucible (100) and is used for crystal growth; A graphite guide plate (500) is disposed above the graphite crucible (100), and the lifting rod (410) of the seed crystal lifting assembly (400) passes through the graphite guide plate (500). During the growth of the seed crystal (700), the graphite guide plate (500) is connected to an external inert gas source and is used to continuously introduce inert gas into the seed crystal lifting assembly (400) to dissipate heat from the seed crystal (700) bonded to the bottom of the seed crystal lifting assembly (400); The graphite guide plate (500) includes: The plate body (510) has a through hole (520) in its middle part for the lifting rod (410) to pass through. Furthermore, the plate body (510) extends downward along the perforation (520) to form an airflow ring (530). The plate body (510) has a plurality of air channels (540) that communicate with the perforation (520) in the radial direction, so as to introduce inert gas from an external inert gas source into the airflow ring (530) to dissipate heat from the seed crystal (700) bonded to the bottom of the seed crystal lifting assembly (400).

2. The silicon carbide single crystal growth apparatus as described in claim 1, characterized in that, The seed crystal pulling assembly (400) also includes: A rotating head (420) is disposed at the bottom of the lifting rod (410), and the bottom surface of the rotating head (420) is used for bonding the seed crystal (700); The diameter of the airflow ring (530) is R1; The diameter of the rotating head (420) is R2; Where R2 > R1, and the units of R2 and R1 are mm.

3. The silicon carbide single crystal growth apparatus as described in claim 2, characterized in that, A protective ring (421) extends upward from the top surface of the rotating head (420) along its edge. The airflow ring (530) is inserted into the protective ring (421); Furthermore, a gap is provided between the airflow ring (530) and the protective ring (421) to allow the inert gas introduced into the seed crystal pulling assembly (400) to be discharged from the gap.

4. The silicon carbide single crystal growth apparatus as described in claim 3, characterized in that, The lower end of the airflow ring (530) is trumpet-shaped; The upper end of the protective ring (421) is constricted; The lower end of the airflow ring (530) is positioned opposite to the upper end of the protective ring (421) to gather and discharge the inert gas that enters the seed crystal pulling assembly (400), thereby reducing the fluctuation of the molten liquid in the graphite crucible (100).

5. The silicon carbide single crystal growth apparatus as described in claim 1, characterized in that, The heating assembly (200) includes: A main heater (210) is disposed around the side wall of the graphite crucible (100) and is used to heat the graphite crucible (100); A secondary heater (220) is disposed on top of the graphite crucible (100) and is used to keep the upper part of the graphite crucible (100) warm.

6. The silicon carbide single crystal growth apparatus as described in claim 1, characterized in that, The drive mechanism includes: Pallet support; A drive shaft is located at the bottom of the support tray and is driven by an external drive motor.

7. The silicon carbide single crystal growth apparatus as described in claim 1, characterized in that, The silicon carbide single crystal growth apparatus also includes a furnace body (600). The graphite crucible (100), heating assembly (200), and seed crystal lifting assembly (400) are disposed in the furnace body, and the lifting rod of the seed crystal lifting assembly (400) extends from the top of the furnace body (600).

8. A method of operating the silicon carbide single crystal growth apparatus as described in claim 1, characterized in that, The working method includes: Step S1: Place the raw materials and flux into a graphite crucible (100) and heat it to a preset temperature using a heating assembly (200) to completely melt the raw materials; In step S2, the seed crystal lifting assembly (400) lowers the seed crystal (700) above the molten liquid, and the heating assembly (200) is turned on; In step S3, the seed crystal lifting assembly (400) lowers the seed crystal (700) to contact the surface of the molten liquid; In step S4, the lifting rod (410) drives the seed crystal (700) to start rotating and lifting. At the same time, the external inert gas source dissipates heat from the seed crystal (700) bonded to the bottom of the seed crystal lifting assembly (400) through the graphite guide plate (500), and the crystal begins to grow.

9. The method of operating the silicon carbide single crystal growth apparatus as described in claim 8, characterized in that, The heating assembly (200) includes: A main heater (210) is disposed around the side wall of the graphite crucible (100) and is used to heat the graphite crucible (100); A secondary heater (220) is disposed on top of the graphite crucible (100) and is used to keep the upper part of the graphite crucible (100) warm; Step S4 also includes: The auxiliary heater (220) adjusts the heat preservation power during crystal growth, and the inert gas source adjusts the inert gas intake during crystal growth. The heat preservation power gradually decreases as the crystal growth time increases; The amount of inert gas introduced gradually decreases as the crystal growth time increases.

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