A silicon carbide crystal growth furnace and growth method using pneumatically conveyed raw materials

Abstract

The present invention belongs to the technical field of silicon carbide crystal growth, and specifically relates to a silicon carbide crystal growth furnace and growth method using pneumatically conveyed raw materials. The growth furnace comprises: a raw material pneumatic conveying pipe that enters a crucible from the bottom; a first guide plate that covers and seals the upper end of the conveying pipe, its edge extending outside the conveying pipe and leaving a gap between it and the inner wall of the crucible, and the outlet of the conveying pipe is below the first guide plate; a second guide plate, one end of which is fixed to the inner wall of the crucible, and the other end of which is zigzag near the edge of the first guide plate and suspended in the air; an inclined guide plate, one end of which is fixed to the outer wall of the conveying pipe, and the other end of which is suspended in the air; a baffle, one end of which is fixed to the inner wall of the crucible or the outer wall of the conveying pipe, and the other end of which is suspended in the air, the inclined guide plate guiding part of the flow out of the outlet to flow downward toward the baffle; the guide plate and the baffle are made of graphite. By continuously conveying raw materials into the crucible, large-sized crystals are grown.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon carbide crystal growth, and in particular relates to a silicon carbide crystal growth furnace and a growth method for pneumatically conveying raw materials. Background Art

[0002] The mainstream SiC crystal growth method is physical vapor transport (PVT). The principle is to load a certain amount of silicon carbide raw material into a relatively closed crucible, and then sublimate carbon powder and silicon powder at a temperature exceeding 2000°C to decompose them into gaseous substances such as Si atoms, Si2C molecules, and SiC2 molecules. Driven by the temperature gradient, these gaseous substances are transported to the cooler silicon carbide seed crystal to form silicon carbide crystals. By controlling the PVT process parameters such as the temperature field and airflow, specific 4H-SiC crystal forms can be grown.

[0003] Affected by factors such as uniform heating and temperature gradient, the size of the graphite crucible is limited. Since the volume of the raw material loaded in the crucible is limited, the size of the grown silicon carbide crystal is also restricted to a certain extent, making it difficult to grow large-sized crystals.

[0004] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or public known technology. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defect that the volume of raw materials loaded in the crucible is limited and it is difficult to grow large-sized crystals. The purpose is to provide a silicon carbide crystal growth furnace and growth method that pneumatically convey raw materials. When used for silicon carbide crystal growth, the raw materials can be continuously pneumatically conveyed during the crystal growth process, and the crystal grows while the raw materials are added, thereby increasing the size of the grown crystal.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a growth furnace for silicon carbide crystals using pneumatic conveying of raw materials, comprising:

[0007] The crucible is arranged in the furnace body, and an opening is provided at the center of the bottom thereof, and the edge of the opening extends vertically upward to form a sleeve;

[0008] a first section of a raw material pneumatic conveying pipeline, which is vertically arranged, extending from the bottom center of the crucible through the sleeve into the crucible, and is sealedly connected to the sleeve;

[0009] a first graphite guide plate, which covers and seals the upper end of the first section of the pneumatic raw material conveying pipeline, with an edge of the first graphite guide plate extending outside the first section of the pneumatic raw material conveying pipeline and a gap between the edge and the inner wall of the crucible; an outlet of the first section of the pneumatic raw material conveying pipeline is located below the first graphite guide plate and above the sleeve, and the outlet is arranged along the circumference of the first section of the pneumatic raw material conveying pipeline;

[0010] A second graphite guide plate, one end of which is fixed to the inner wall of the crucible, and the other end of which is suspended near the edge of the first graphite guide plate, wherein the suspended end and the edge of the first graphite guide plate are arranged in a zigzag manner to form a zigzag flow channel;

[0011] An inclined graphite guide plate, one end of which is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end of which is suspended in the air, with the fixed end at a height higher than the suspended end;

[0012] A graphite deflector, one end of which is fixed on the inner wall of the crucible or the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end of which is suspended in the air, with the height of the fixed end being higher than the height of the suspended end. The inclined graphite guide plate guides part of the logistics flowing out of the outlet to flow downward toward the graphite deflector, and the airflow returns after the logistics flows to the graphite deflector, and the solid raw material falls into the lower part of the crucible.

[0013] In some preferred embodiments, the edge of the first graphite guide plate is provided with a first protrusion surrounding the circumference of the first graphite guide plate, and the suspended end of the second graphite guide plate is provided with a second protrusion offset opposite to the first protrusion, and the first protrusion and the second protrusion are offset opposite to each other to form an S-shaped tortuous logistics channel.

[0014] Preferably, it also includes:

[0015] a second-first graphite guide plate, which is fixedly arranged on the upper surface of the first graphite guide plate along the circumference of the first graphite guide plate, with a gap between its edge and the inner wall of the crucible, and at least two third protrusions arranged on its edge along the circumference of the second-first graphite guide plate;

[0016] The second graphite guide plate has one end fixed on the inner wall of the crucible and the other end suspended near the edge of the first graphite guide plate. The suspended end is provided with at least two fourth protrusions, and the at least two fourth protrusions are staggered relative to the at least two third protrusions to form an S-shaped tortuous logistics channel.

[0017] Preferably, the edge of the first graphite guide plate is located below the suspended end of the second graphite guide plate, and the edge of the second-first graphite guide plate is located below the suspended end of the second-second graphite guide plate;

[0018] The first protrusion and the third protrusion are respectively located on the upper surface of the edge of the first graphite guide plate and the upper surface of the edge of the second-first graphite guide plate, and the second protrusion and the fourth protrusion are respectively located on the lower surface of the suspended end of the second graphite guide plate and the lower surface of the suspended end of the second-second graphite guide plate.

[0019] In some preferred embodiments, the inclined graphite guide plate includes a structure of the first graphite guide plate extending outside the first section of the raw material pneumatic conveying pipeline, and the height of the position where the first graphite guide plate is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline is higher than the height of the edge.

[0020] Preferably, it includes an inclined graphite guide plate located below the first graphite guide plate, with its suspended end extending vertically downward;

[0021] The graphite baffle includes a first graphite baffle and a second graphite baffle, one end of the first graphite baffle is fixed on the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end of the first graphite baffle is suspended, one end of the second graphite baffle is fixed on the inner wall of the crucible, and the other end of the second graphite baffle is suspended.

[0022] In some preferred embodiments, the interior of the first section of the raw material pneumatic conveying pipeline is sheathed with an infrared temperature measuring tube, the upper end of the infrared temperature measuring tube is higher than the upper end of the first section of the raw material pneumatic conveying pipeline, the first graphite guide plate is fixedly arranged on the outer wall of the infrared temperature measuring tube and is arranged along the circumference of the infrared temperature measuring tube, a graphite plate with holes is sheathed on the outer surface of the top end of the infrared temperature measuring tube, the gas flows upward through the graphite plate with holes, and the solid raw material cannot flow upward through the graphite plate with holes, the graphite plate with holes divides the crucible into an upper chamber and a lower chamber, the top of the upper chamber has a seed crystal mounting portion, the first graphite guide plate, the second graphite guide plate, the inclined graphite guide plate and the graphite deflector are all located in the lower chamber.

[0023] Preferably, a horizontal orifice plate and a baffle are built into the lower portion of the first section of the raw material pneumatic conveying pipeline, and the baffle is located below the orifice plate;

[0024] The growth furnace also includes a second section of raw material pneumatic conveying pipeline, which is connected to the side wall of the lower part of the first section of raw material pneumatic conveying pipeline and the connection position is located above the orifice plate. The bottom of the first section of raw material pneumatic conveying pipeline is connected to an inflation pipeline, and the gas passes through the baffle and the orifice plate in turn and flows through the first section of raw material pneumatic conveying pipeline, and the raw material particles cannot be located below the baffle.

[0025] Preferably, the baffle comprises:

[0026] a first baffle fixedly sleeved on the outer wall of the infrared temperature measuring tube, with a gap between its edge and the inner wall of the first section of the raw material pneumatic conveying pipeline;

[0027] The second baffle has one end fixed on the inner wall of the first section of the raw material pneumatic conveying pipeline, and the other end is suspended near the edge of the first baffle. The suspended end is zigzagly arranged near the edge of the first baffle to form a zigzag flow channel.

[0028] Preferably, the edge of the first baffle is provided with a protrusion surrounding the circumference of the first baffle, and the suspended end of the second baffle has a protrusion offset relative to the protrusion on the first baffle, and the protrusion on the first baffle and the protrusion on the second baffle are offset relative to each other to form an S-shaped tortuous logistics channel.

[0029] In some preferred embodiments, a feeding device is further included, the feeding device comprising a feeding tank and a spiral feeding member, the feeding tank is provided with an air supply pipe, the spiral feeding member is arranged in the feeding tank and extends along the central axis of the feeding tank for spiral feeding;

[0030] The feeding tank is provided with an inflation pipe, the spiral feeding piece has a ventilation channel, the ventilation channel is connected to a plurality of air holes and the plurality of air holes are distributed along the axial direction of the spiral feeding piece, the inflation pipe on the feeding tank, the ventilation channel and the air holes are connected, the bottom outlet of the feeding tank is connected to the raw material pneumatic conveying pipeline including the first section of the raw material pneumatic conveying pipeline, and at least one inflation pipe is connected to the raw material pneumatic conveying pipeline.

[0031] In a second aspect, the present invention provides a method for growing silicon carbide crystals, which is carried out in the silicon carbide crystal growth furnace for pneumatically conveying raw materials as described in the first aspect, and the method for growing silicon carbide crystals includes: heating the crucible to the sublimation temperature of the raw materials, pneumatically conveying the raw materials into the crucible through the first section of the raw materials pneumatic conveying pipeline, the sublimation gas generated by the sublimation of the raw materials flows through the tortuous logistics channel formed by the first graphite guide plate and the second graphite guide plate and then flows to the top of the crucible, the inclined graphite guide plate guides part of the logistics flowing out of the outlet of the first section of the raw materials pneumatic conveying pipeline to flow downward toward the graphite deflector, and the logistics flows to the graphite deflector and the airflow returns after the logistics flows to the graphite deflector, and the solid raw material falls into the lower part of the crucible.

[0032] In some preferred embodiments, after some raw material particles flow out of the second section of the raw material pneumatic conveying pipeline, they fall onto the orifice plate built into the first section of the raw material pneumatic conveying pipeline. The inflation pipeline at the bottom of the first section of the raw material pneumatic conveying pipeline is filled with inert gas, and the inert gas flows through the baffle built into the first section of the raw material pneumatic conveying pipeline and the orifice plate in turn. The raw material particles cannot be located below the baffle, so that the raw material particles on the orifice plate leave the orifice plate and flow through the first section of the raw material pneumatic conveying pipeline into the crucible.

[0033] In some preferred embodiments, the raw materials are loaded into a feeding tank, the vacuum degree in the feeding tank is adjusted to be the same as the vacuum degree of the working chamber where the crucible is located, the spiral feeding piece is controlled to drive the raw materials to move downward, and inert gas is introduced into the feeding tank through an air supply pipe. The inert gas is introduced into the ventilation channel of the spiral feeding piece through an inflation pipe on the feeding tank. The inert gas is ejected through the air holes to accelerate the raw materials to move downward into the raw material pneumatic conveying pipe. Gas is supplied to the raw material pneumatic conveying pipe through at least one inflation pipe connected to the raw material pneumatic conveying pipe. Under the action of the pressure difference between the crucible and the feeding tank, the raw materials are pneumatically conveyed into the crucible.

[0034] In some preferred embodiments, the particle size of the pneumatically conveyed raw material is 2 mm to 5 mm; and / or the ratio of the atomic percentage of silicon to the atomic percentage of carbon in the pneumatically conveyed raw material is 0.95 to 0.995.

[0035] The present invention provides a growth furnace for silicon carbide crystals using pneumatic conveying of raw materials, comprising a crucible disposed within a furnace body, wherein an opening is provided at the center of the bottom of the crucible, a vertically disposed first section of a raw material pneumatic conveying pipeline extending from the center of the bottom of the crucible into the crucible, and capable of supplying raw materials into the crucible through pneumatic conveying of inert gas; a first graphite guide plate covers and seals the upper end of the first section of the raw material pneumatic conveying pipeline, an edge of the first graphite guide plate extending outside the first section of the raw material pneumatic conveying pipeline and leaving a gap between the edge and the inner wall of the crucible, and an outlet of the first section of the raw material pneumatic conveying pipeline is located below the first graphite guide plate. The second graphite guide plate is arranged along the circumference of the first section of the raw material pneumatic conveying pipeline, one end of the second graphite guide plate is fixed on the inner wall of the crucible, and the other end is suspended near the edge of the first graphite guide plate, and the suspended end is arranged close to the edge of the first graphite guide plate to form a tortuous logistics channel. The tortuous logistics channel formed by the first graphite guide plate and the second graphite guide plate can prevent the sublimation gas from carrying small-sized raw materials that have not had time to sublimate to reach the seed crystal or crystal, thereby affecting the quality of the crystal. At the same time, the small-sized raw materials that have not had time to sublimate and fall into the tortuous logistics channel are further sublimated; one end of the inclined graphite guide plate One end is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end is suspended, and the height of the fixed end is higher than the height of the suspended end. One end of the graphite baffle is fixed to the inner wall of the crucible or the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end is suspended, and the height of the fixed end is higher than the height of the suspended end. Through the arrangement of the inclined graphite guide plate and the graphite baffle, the large-particle size raw material is guided to flow to the graphite baffle through the inclined graphite guide plate, and partially sublimates in the process of flowing to the graphite baffle. The sublimated gas rebounds and returns after flowing to the graphite baffle, and quickly condenses into crystals at the seed crystal, and the small part that is not sublimated The raw materials fall into the lower part of the crucible and are further sublimated and vaporized, and can be fully sublimated; the guide plates and the deflector plates of the present invention are both made of graphite materials, and when the inner and outer walls of the crucible are heated, the guide plates and the deflector plates are also heated at the same time, which can promote the full sublimation of the raw materials; when silicon carbide crystals are grown, there is no need to add raw materials to the crucible in advance, the crucible is heated to the sublimation temperature of the raw materials, and the raw materials are pneumatically conveyed into the crucible through the raw material pneumatic conveying pipeline. The pneumatically conveyed raw materials can be fully sublimated and quickly condensed into crystals at the seed crystal. By continuously pneumatically conveying raw materials into the crucible, large-sized, high-quality crystals can be grown. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1It is a structural schematic diagram of a specific embodiment of a growth furnace for silicon carbide crystals using pneumatic conveying of raw materials according to the present invention;

[0038] Figure 2 This is a partial structural diagram of a specific embodiment of the coordination between the feeding device and the raw material pneumatic conveying pipeline of the present invention;

[0039] Figure 3 It is a partial structural diagram of a specific embodiment of the present invention, in which the crucible and the first section of the raw material pneumatic conveying pipeline are matched;

[0040] Figure 4 This is a partial structural diagram of a specific embodiment of the coordination between the first section of the raw material pneumatic conveying pipeline and the second section of the raw material pneumatic conveying pipeline of the present invention;

[0041] Figure 5 yes Figure 4 A partial enlarged view of the lower structure of the first section of the raw material pneumatic conveying pipeline.

[0042] Description of Reference Numerals

[0043] 1. Crucible; 101. Sleeve; 2. First section of raw material pneumatic conveying pipeline; 3. First graphite guide plate; 301. First protrusion; 4. Second graphite guide plate; 401. Second protrusion; 5. Graphite baffle; 501. First graphite baffle; 502. Second graphite baffle; 6. Second first graphite guide plate; 601. Third protrusion; 7. Second second graphite guide plate; 701. Fourth protrusion; 8. Infrared temperature measuring tube; 9. Perforated Graphite plate; 10. Orifice plate; 11. Baffle; 1101. First baffle; 1102. Second baffle; 1103. Protrusion; 12. Second section of raw material pneumatic conveying pipeline; 13. Feeding device; 1301. Feeding tank; 1302. Spiral feeding piece; 1303. Gas supply pipeline; 14. Seed crystal mounting part; 15. Observation window; 16. First bellows; 17. Sleeve; 18. Lifting shaft; 19. Gap for gas outflow. DETAILED DESCRIPTION

[0044] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0045] In this article, unless otherwise specified, directional words such as "up, down, left, right" are generally understood in combination with the directions shown in the drawings and actual applications, and "inside and outside" refer to the inside and outside of the outline of the component.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0048] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0049] The inventors of the present invention have found that the physical vapor transport method for growing silicon carbide crystals is affected by uniform heating and temperature gradients, the size of the graphite crucible is limited, and the volume of the raw material loaded in the crucible is limited, making it difficult to grow large-sized crystals.

[0050] In this regard, first of all, refer to Figure 1 and Figure 3 ( Figure 3 The arrow in the middle indicates the flow direction of the material flow). The present invention provides a silicon carbide crystal growth furnace for pneumatically conveying raw materials, comprising:

[0051] The crucible 1 is arranged in the furnace body, and an opening is provided at the center of the bottom thereof, and the edge of the opening extends vertically upward to form a sleeve 101;

[0052] The first section of the raw material pneumatic conveying pipeline 2 is vertically arranged, extending from the bottom center of the crucible 1 through the sleeve 101 into the crucible 1, and is sealed with the sleeve 101;

[0053] a first graphite guide plate 3, which covers and seals the upper end of the first section of the raw material pneumatic conveying pipeline 2, with its edge extending to the outside of the first section of the raw material pneumatic conveying pipeline 2 and leaving a gap between its edge and the inner wall of the crucible; an outlet of the first section of the raw material pneumatic conveying pipeline 2 is located below the first graphite guide plate 3 and above the sleeve 101, and the outlet is arranged along the circumference of the first section of the raw material pneumatic conveying pipeline 2;

[0054] A second graphite guide plate 4, one end of which is fixed to the inner wall of the crucible, and the other end of which is suspended near the edge of the first graphite guide plate 3, wherein the suspended end and the edge of the first graphite guide plate 3 are arranged in a zigzag manner to form a zigzag flow channel;

[0055] An inclined graphite guide plate, one end of which is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipe 2, and the other end of which is suspended in the air, with the height of the fixed end being higher than the height of the suspended end;

[0056] The graphite baffle 5 has one end fixed on the inner wall of the crucible or the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipe 2, and the other end is suspended in the air, and the height of the fixed end is higher than the height of the suspended end. The inclined graphite guide plate guides part of the logistics flowing out of the outlet to flow downward toward the graphite baffle 5. After the logistics flows to the graphite baffle 5, the air flow returns, and the solid raw material falls into the lower part of the crucible 1.

[0057] The growth furnace for silicon carbide crystals with pneumatically conveyed raw materials of the present invention is provided with an opening at the bottom center of a crucible arranged in the furnace body, and a vertically arranged first section of the raw material pneumatic conveying pipeline extends from the bottom center of the crucible into the crucible, and can provide raw materials into the crucible by means of pneumatic conveying of inert gas. The edge of the central opening extends vertically upward to form a sleeve, and the first section of the raw material pneumatic conveying pipe extends from the bottom center of the crucible through the sleeve into the crucible. The first section of the raw material pneumatic conveying pipeline is sealed with the sleeve, and can conveniently seal and connect the first raw material pneumatic conveying pipeline and the crucible.

[0058] The growth furnace of the present invention comprises a first guide plate covering and sealing the upper end of the first section of the raw material pneumatic conveying pipeline, an edge of which extends to the outside of the first section of the raw material pneumatic conveying pipeline and a gap is left between the edge and the inner wall of the crucible, one end of the second graphite guide plate is fixed to the inner wall of the crucible, and the other end is suspended near the edge of the first graphite guide plate, the suspended end of the second graphite guide plate is arranged close to the edge of the first graphite guide plate in a zigzag manner to form a zigzag flow channel, the outlet of the first section of the raw material pneumatic conveying pipeline is located below the first graphite guide plate and above the sleeve, and the outlet is along the first section of the raw material pneumatic conveying pipeline. The pneumatic conveying pipeline of the material is set circumferentially, and the crucible is heated to the sublimation temperature of the raw material. The sublimation gas of the pneumatically conveyed raw material flows to the top of the crucible after passing through the tortuous logistics channel composed of the first graphite guide plate and the second graphite guide plate. The setting of the tortuous logistics channel can prevent the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, affecting the quality of the crystal. The graphite guide plate is made of graphite and the guide plate will also be heated. The temperature of the guide plate can meet the volatilization temperature of the raw material. The small-particle raw materials that have not had time to sublimate and fall into the tortuous logistics channel will further sublime.

[0059] In the growth furnace of the present invention, one end of the inclined guide plate is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end is suspended in the air, and the height of the fixed end is higher than the height of the suspended end. One end of the graphite baffle is fixed on the inner wall of the crucible or the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline, and the other end is suspended in the air, and the height of the fixed end is higher than the height of the suspended end. Through the arrangement of the inclined graphite guide plate and the graphite baffle, large-particle raw materials are guided by the inclined graphite guide plate to flow toward the graphite baffle, and partially sublime in the process of flowing toward the graphite baffle. The sublimated gas rebounds and returns after flowing toward the graphite baffle, and quickly condenses into crystals at the seed crystal. The small amount of raw materials that have not sublimated falls into the lower part of the crucible for further sublimation, and can be fully sublimated.

[0060] The vertically arranged first section of the raw material pneumatic conveying pipeline of the present invention extends from the bottom center of the crucible into the crucible. The sublimated gas of the pneumatically conveyed raw material flows to the top of the crucible after passing through the tortuous logistics channel composed of the first graphite guide plate and the second graphite guide plate. The large-particle raw material is guided by the inclined graphite guide plate to flow to the graphite deflector. Part of it sublimates in the process of flowing to the graphite deflector. The sublimated gas rebounds and returns after flowing to the graphite deflector. The small amount of raw material that has not sublimated falls into the lower part of the crucible for further sublimation. The sublimated gas is effectively separated from the unsublimated part of the raw material, and the gas condenses upward into crystals, and the solid particles have sufficient time to be heated and sublimated.

[0061] The guide plates and baffles of the present invention are both made of graphite. As the inner and outer walls of the crucible are heated, the guide plates and baffles are also heated simultaneously based on the principles of heat conduction and heat radiation of the materials, promoting full and rapid sublimation of the raw materials. The heating of the guide plates and baffles ensures a more uniform temperature within the crucible, preventing insufficient sublimation of the raw materials in low-temperature areas and carbonization of the raw materials in high-temperature areas, which could affect crystal quality.

[0062] The growth furnace of the present invention eliminates the need to pre-add raw materials to a crucible during silicon carbide crystal growth. Instead of heating the crucible to the sublimation temperature of the raw materials, the raw materials are pneumatically conveyed into the crucible via a raw material pneumatic conveying pipe. The pneumatically conveyed raw materials are able to rapidly sublime and quickly condense into crystals at the seed crystals. By continuously pneumatically conveying raw materials into the crucible, large, high-quality crystals can be grown. The growth furnace of the present invention continuously adds raw materials during crystal growth, allowing crystal growth to proceed simultaneously with the addition of raw materials. This allows the use of a smaller crucible for crystal growth, allowing large crystals to be grown while reducing crucible costs.

[0063] The present invention does not limit the method for sealingly connecting the first section of the raw material pneumatic conveying pipeline to the sleeve; for example, a threaded connection may be used. The crucible of the present invention includes a crucible wall that circumferentially surrounds the crucible. The inner wall of the crucible refers to the inner side of the crucible wall. The sleeve includes an inner wall and an outer wall. The outer wall of the sleeve refers to the wall of the sleeve that does not contact the outer wall of the first section of the raw material pneumatic conveying pipeline.

[0064] It is understood that the crucible of the present invention has a gap through which gas can flow out of the crucible. For example, see Figure 3 The crucible cover of the crucible is non-sealedly connected to the upper part of the crucible wall, and a gap 19 is left between the two for gas to flow out.

[0065] The second graphite guide plate of the present invention can be arranged along the circumference of the inner wall of the crucible. It can be an annular second graphite guide plate, or it can have several second graphite guide plates distributed along the circumference of the inner wall of the crucible. Preferably, it is an annular second graphite guide plate arranged along the circumference of the inner wall of the crucible, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, affecting the crystal quality.

[0066] The suspended end of the second graphite guide plate of the present invention is arranged in a zigzag manner adjacent to the edge of the first graphite guide plate to form a zigzag logistics channel. The present invention does not limit the form of the zigzag proximity arrangement. In some preferred embodiments, the edge of the first graphite guide plate 3 is provided with a first protrusion 301 that surrounds the circumference of the first graphite guide plate 3, and the suspended end of the second graphite guide plate 4 is provided with a second protrusion 401 that is offset from the first protrusion 301. The first protrusion 301 and the second protrusion 401 are offset from each other to form an S-shaped zigzag logistics channel. Under this preferred embodiment, it is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not yet sublimated to reach the crystal or seed crystal, thereby affecting the crystal quality. The present invention does not limit the relative positions of the edge of the first graphite guide plate and the suspended end of the second graphite guide plate. The edge of the first graphite guide plate 3 can be located below the suspended end of the second graphite guide plate 4, or the edge of the first graphite guide plate 3 can be located above the suspended end of the second graphite guide plate 4. The first protrusion 301 and the second protrusion 401 are arranged facing each other. For the first case, the first protrusion 301 of the first graphite guide plate is located on the upper surface of the edge of the first graphite guide plate 3, that is, it is convex upward, and the second protrusion 401 of the second graphite guide plate 4 is located on the lower surface of the suspended end of the second graphite guide plate 4, that is, In the second case, the first protrusion 301 of the first graphite guide plate is located on the lower surface of the edge of the first graphite guide plate 3, that is, it is convex downward, and the second protrusion 401 of the second graphite guide plate is located on the upper surface of the suspended end of the second graphite guide plate 4, that is, it is convex upward. Preferably, the edge of the first graphite guide plate is located below the suspended end of the second graphite guide plate, the first protrusion is located on the upper surface of the edge of the first graphite guide plate, and the second protrusion is located on the lower surface of the suspended end of the second graphite guide plate. This is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal and crystal, thereby affecting the crystal quality. The staggered setting refers to the protrusion directions of the first protrusion 301 and the second protrusion 401 being staggered and not on the same straight line.

[0067] Preferably, the growth furnace of the present invention further comprises a sub-first graphite guide plate 6, which is fixedly arranged on the upper surface of the first graphite guide plate 3 along the circumference of the first graphite guide plate 3, with a gap between its edge and the inner wall of the crucible, and at least two third protrusions 601 surrounding the circumference of the sub-first graphite guide plate 6 are provided on its edge;

[0068] The second graphite guide plate 7 has one end fixed on the inner wall of the crucible and the other end suspended near the edge of the first graphite guide plate 6. At least two fourth protrusions 701 are provided on the suspended end. At least two of the fourth protrusions 701 are staggered with at least two of the third protrusions 601 to form an S-shaped tortuous logistics channel.

[0069] Under this preferred embodiment, a sub-first graphite guide plate 6 is provided on the upper surface of the first graphite guide plate along the circumference of the first graphite guide plate 3, with a gap between the edge and the inner wall of the crucible. A third protrusion 601 is provided on the edge of the sub-first graphite guide plate 6 and surrounds the circumference of the sub-first graphite guide plate. A sub-second graphite guide plate 7 is provided with one end fixed on the inner wall of the crucible and the other end suspended near the edge of the sub-first graphite guide plate 6. A fourth protrusion 701 is provided on the suspended end of the sub-second graphite guide plate 7 and is offset from the third protrusion 601. By arranging the sub-first graphite guide plate and the sub-second graphite guide plate, the protrusions thereon form an S-shaped tortuous logistics channel, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, thereby affecting the quality of the crystal. The present invention is provided with at least two third protrusions 601 surrounding the circumference of the second first graphite guide plate 6, and at least two fourth protrusions 701 are provided which are offset relative to the at least two third protrusions 601. The length of the S-shaped tortuous logistics channel is longer, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, thereby affecting the crystal quality. The present invention does not limit the relative positions of the edge of the sub-first graphite guide plate and the suspended end of the sub-second graphite guide plate. The edge of the sub-first graphite guide plate 6 can be located below the suspended end of the sub-second graphite guide plate 7, or the edge of the sub-first graphite guide plate 6 can be located above the suspended end of the sub-second graphite guide plate 7. At least two fourth protrusions 701 and at least two third protrusions 601 are arranged facing each other. For the first case, the third protrusion 601 on the sub-first graphite guide plate 6 is located on the upper surface of the edge of the sub-first graphite guide plate 6, that is, it is convex upward, and the fourth protrusion 701 on the sub-second graphite guide plate 7 is located at the suspended end of the sub-second graphite guide plate 7. The lower surface of the second graphite guide plate 6 is convex downward. For the second case, the third protrusion 601 of the second-first graphite guide plate 6 is located on the lower surface of the edge of the second-first graphite guide plate 6, that is, convex downward. The fourth protrusion 701 of the second-second graphite guide plate 7 is located on the upper surface of the suspended end of the second-second graphite guide plate 7, that is, convex upward. Preferably, the edge of the second-first graphite guide plate is located below the suspended end of the second-second graphite guide plate, the third protrusion is located on the upper surface of the edge of the second-first graphite guide plate, and the fourth protrusion is located on the lower surface of the suspended end of the second-second graphite guide plate. This is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, thereby affecting the crystal quality. The staggered setting refers to the alternating arrangement of the third protrusion 601 and the fourth protrusion 701, and the protrusion directions of the third protrusion 601 and the fourth protrusion 701 are staggered and not on the same straight line.

[0070] The secondary graphite guide plate of the present invention can be arranged along the circumference of the inner wall of the crucible. It can be an annular secondary graphite guide plate, or it can have several secondary graphite guide plates distributed along the circumference of the inner wall of the crucible. Preferably, it is an annular secondary graphite guide plate arranged along the circumference of the inner wall of the crucible, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to reach the seed crystal or crystal, affecting the quality of the crystal.

[0071] The structure of the first graphite guide plate of the present invention extending outside the first section of the pneumatic raw material conveying pipe 2 can be arranged at an angle or horizontally. In some preferred embodiments, the inclined graphite guide plate includes a structure of the first graphite guide plate 3 extending outside the first section of the pneumatic raw material conveying pipe 2, and the height of the location where the first graphite guide plate 3 is fixedly connected to the outer wall of the first section of the pneumatic raw material conveying pipe 2 is higher than the height of the edge. In this preferred embodiment, the first graphite guide plate can simultaneously prevent the sublimation gas from carrying small-particle raw materials that have not yet sublimated to reach the seed crystal or crystal, thereby affecting the crystal quality, and guide the large-particle raw materials to flow toward the graphite baffle.

[0072] The present invention can also separately provide an inclined graphite guide plate. Preferably, it includes an inclined graphite guide plate located below the first graphite guide plate 3, with its suspended end extending vertically downward;

[0073] The graphite baffle 5 includes a first graphite baffle 501 and a second graphite baffle 502, one end of the first graphite baffle 501 is fixed on the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline 2, and the other end of the first graphite baffle 501 is suspended, one end of the second graphite baffle 502 is fixed on the inner wall of the crucible, and the other end of the second graphite baffle 502 is suspended.

[0074] The outlet of the first section of the raw material pneumatic conveying pipeline 2 is located below the first graphite guide plate 3. In this preferred embodiment, an inclined graphite guide plate is provided below the first graphite guide plate 3. By providing two inclined graphite guide plates, it is more conducive to guiding the large-particle raw materials to flow toward the graphite baffle. The suspended end of the inclined graphite guide plate below the first graphite guide plate 3 extends vertically downward. The graphite baffle 5 includes a first graphite baffle 501 and a second graphite baffle 502. One end of the first graphite baffle 501 is fixed to the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline 2. On the top, the other end of the first graphite baffle 501 is suspended, one end of the second graphite baffle 502 is fixed on the inner wall of the crucible, and the other end of the second graphite baffle 502 is suspended, and the inclined graphite guide plate guides part of the logistics to flow to the first graphite baffle 501, and the other part of the logistics flows to the second graphite baffle 502, so that the input gas is transported downward at different angles, which is more conducive to preventing the collision and agglomeration of fine particles formed in the process of thermal sublimation of solid particles, and is more conducive to sublimation. The upper and lower surfaces of the inclined graphite guide plate below the first graphite guide plate 3 can both play a role in guiding logistics. The fixed end of the inclined graphite guide plate arranged below the first graphite guide plate 3 of the present invention can be located below the logistics outlet of the first section of the raw material pneumatic conveying pipeline, preferably located between two layers of the multi-layer outlet distributed along the axial direction of the first section of the raw material pneumatic conveying pipeline 2, that is, the upper and lower sections of the first section of the raw material pneumatic conveying pipeline 2 of the fixed end of the inclined graphite guide plate are provided with airflow outlets, which guide the airflow diversion to move downward, which is more conducive to the sublimation of solid particles in the raw material.

[0075] In some preferred embodiments, the interior of the first section of the raw material pneumatic conveying pipeline 2 is sheathed with an infrared temperature measuring tube 8, the upper end of the infrared temperature measuring tube 8 is higher than the upper end of the first section of the raw material pneumatic conveying pipeline 2, the first graphite guide plate 3 is fixedly arranged on the outer wall of the infrared temperature measuring tube 8 and is arranged along the circumference of the infrared temperature measuring tube 8, the top outer surface of the infrared temperature measuring tube 8 is sheathed with a perforated graphite plate 9, the gas flows upward through the perforated graphite plate 9, and the solid raw material cannot flow upward through the perforated graphite plate 9, the perforated graphite plate 9 divides the crucible into an upper chamber and a lower chamber, the top of the upper chamber has a seed crystal mounting portion 14, the first graphite guide plate 3, the second graphite guide plate 4, the inclined graphite guide plate and the graphite deflector 5 are all located in the lower chamber.

[0076] Under this preferred embodiment, by setting an infrared temperature measuring tube, it is possible to measure the temperature of the crystal surface and calculate the growth rate to control the delivery speed and weight of the raw material, form a closed-loop control of the crystal growth process, keep the temperature difference between the crystal growth interface and the raw material surface relatively constant, maintain the crystal growth interface stable, and obtain silicon carbide crystals with uniform internal quality. A perforated graphite plate is sleeved on the outer surface of the top of the infrared temperature measuring tube, and the perforated graphite plate divides the crucible into an upper chamber and a lower chamber. The top of the upper chamber has a seed crystal mounting portion, and the first graphite guide plate, the second graphite guide plate, the inclined graphite guide plate and the graphite baffle are all located in the lower chamber. The gas flows upward through the perforated graphite plate, and the solid raw material cannot flow upward through the perforated graphite plate, which is more conducive to preventing small-particle raw materials from reaching the seed crystal or crystal and affecting the crystal quality.

[0077] Preferably, a horizontal orifice plate 10 and a baffle 11 are built into the lower portion of the first section of the raw material pneumatic conveying pipeline 2, and the baffle 11 is located below the orifice plate 10;

[0078] The growth furnace also includes a second section of raw material pneumatic conveying pipe 12, which is connected to the side wall of the lower part of the first section of raw material pneumatic conveying pipe 2 and the connection position is located above the orifice plate 10. The bottom of the first section of raw material pneumatic conveying pipe 2 is connected to an inflation pipe, and the gas passes through the baffle 11 and the orifice plate 10 in turn and flows through the first section of raw material pneumatic conveying pipe 2, and the raw material particles cannot be located below the baffle 11.

[0079] Under this preferred embodiment, it also includes a second section of raw material pneumatic conveying pipe 12 which is connected to the side wall of the lower part of the first section of raw material pneumatic conveying pipe. After the raw material comes out of the second section of raw material pneumatic conveying pipe, it flows upward through the first section of raw material pneumatic conveying pipe 2 and then enters the crucible 1. The interior of the first section of raw material pneumatic conveying pipe 2 is provided with an infrared temperature measuring tube 8, which is more conducive to preventing the pneumatic conveying of raw materials from interfering with infrared temperature measurement. A horizontal orifice plate is built into the lower part of the first section of the raw material pneumatic conveying pipeline, and the position where the second section of the raw material pneumatic conveying pipeline is connected to the first section of the raw material pneumatic conveying pipeline is located above the orifice plate. The bottom of the first section of the raw material pneumatic conveying pipeline is connected to an inflation pipeline. After the raw material comes out of the second section of the raw material pneumatic conveying pipeline, some large particles fall on the orifice plate. The inflation pipeline connected to the bottom of the first section of the raw material pneumatic conveying pipeline is filled with inert gas, which can enable the raw material particles on the orifice plate 10 to leave the orifice plate 10 and flow through the first section of the raw material pneumatic conveying pipeline 2 and then enter the crucible 1. A baffle 11 is set below the orifice plate 10, and the gas passes through the baffle 11 and the orifice plate 10 in turn and flows through the first section of the raw material pneumatic conveying pipeline 2. The raw material particles cannot be located below the baffle 11, which is more conducive to avoiding the raw material particles from clogging the inflation pipeline.

[0080] Preferably, the second section of the raw material pneumatic conveying pipeline 12 is connected to one side of the first section of the raw material pneumatic conveying pipeline 2, and an observation window 15 is provided on the side of the first section of the raw material pneumatic conveying pipeline 2 away from the second section of the raw material pneumatic conveying pipeline 12. The observation window 15 and the second section of the raw material pneumatic conveying pipeline 12 are located on opposite sides of the first section of the raw material pneumatic conveying pipeline 2, which is more conducive to observing the flow of raw materials.

[0081] The present invention does not limit the form of the baffle, as long as it allows gas to pass through and blocks the passage of raw material particles. In some preferred embodiments, the baffle includes: a first baffle 1101, which is fixedly mounted on the outer wall of the infrared temperature measuring tube 8, with a gap between its edge and the inner wall of the first section of the raw material pneumatic conveying pipe 2; a second baffle 1102, one end of which is fixedly mounted on the inner wall of the first section of the raw material pneumatic conveying pipe 2, and the other end of which is suspended near the edge of the first baffle 1101, and its suspended end is arranged in a zigzag manner close to the edge of the first baffle 1101 to form a zigzag flow channel. The baffle form under this preferred embodiment is more conducive to blocking raw material particles and preventing raw material particles from clogging the inflation pipe. The second baffle of the present invention can be disposed circumferentially along the inner wall of the first section of the pneumatic raw material conveying pipe 2. It can be an annular second baffle, or it can include multiple second baffles distributed circumferentially along the inner wall of the first section of the pneumatic raw material conveying pipe. Preferably, an annular second baffle disposed circumferentially along the inner wall of the first section of the pneumatic raw material conveying pipe is more conducive to blocking raw material particles and preventing raw material particles from clogging the aeration pipe. Preferably, the edge of the first baffle 1101 is provided with a protrusion 1103 that surrounds the first baffle 1101, and the suspended end of the second baffle 1102 is provided with a protrusion 1103 that is offset from the protrusion 1103 on the first baffle 1101. The protrusions 1103 on the first baffle 1101 and the protrusions 1103 on the second baffle 1102 are offset from each other to form an S-shaped tortuous logistics channel. The baffle form under this preferred embodiment is more conducive to blocking raw material particles and preventing raw material particles from clogging the aeration pipe. The present invention does not limit the relative positions of the edge of the first baffle and the suspended end of the second baffle. The edge of the first baffle may be located below the suspended end of the second baffle, or the edge of the first baffle may be located above the suspended end of the second baffle. The protrusions on the first baffle and the protrusions on the second baffle are arranged opposite to each other, which means that for the first case, the protrusion of the first baffle is located on the upper surface of the edge of the first baffle, that is, it is convex upward, and the protrusion of the second baffle is located on the lower surface of the suspended end of the second baffle, that is, it is convex downward. For the second case, the protrusion of the first baffle is located on the lower surface of the edge of the first baffle, that is, it is convex downward, and the protrusion of the second baffle is located on the upper surface of the suspended end of the second baffle, that is, it is convex upward. The staggered setting means that the protrusion directions of the protrusions on the first baffle and the protrusions on the second baffle are staggered and are not on the same straight line.

[0082] The lower end of the heating portion on the outside of the crucible of the present invention is preferably lower than the crucible, so that the raw materials are preheated before entering the crucible, thereby promoting the rapid sublimation of the raw materials transported by pneumatic means.

[0083] In some preferred embodiments, the growth furnace further includes a feeding device 13, which includes a feeding tank 1301 and a spiral feeding member 1302. The feeding tank 1301 is provided with a gas supply pipe 1303. The spiral feeding member 1302 is disposed in the feeding tank 1301 and extends along the central axis of the feeding tank 1301 to feed the material in a spiral manner.

[0084] The feeding tank 1301 is provided with an inflation pipe, and the spiral feeding piece 1302 has a ventilation channel. The ventilation channel is connected to a plurality of air holes, and the plurality of air holes are distributed along the axial direction of the spiral feeding piece 1302. The inflation pipe, the ventilation channel and the air holes on the feeding tank 1301 are connected. The bottom outlet of the feeding tank 1301 is connected to the raw material pneumatic conveying pipeline including the first section of the raw material pneumatic conveying pipeline 2, and at least one inflation pipe is connected to the raw material pneumatic conveying pipeline.

[0085] In this preferred embodiment, the raw material pneumatic conveying pipeline is connected to at least one inflation pipeline to supplement the inert gas, which can synergistically promote the raw material to completely reach the crucible and is more conducive to preventing the material from falling or backflowing.

[0086] Preferably, the spiral feeding member 1302 includes a rotating shaft and blades, the blades spirally surround the part of the rotating shaft located in the feeding tank 1301 and extend along the axial direction of the rotating shaft, and the ventilation channel and the air hole are provided on the rotating shaft; the top of the rotating shaft is connected to the outlet of the inflation pipe, which is more conducive to accelerating the movement of materials.

[0087] The raw material pneumatic conveying pipeline of the present invention may include multiple sections of raw material pneumatic conveying pipelines in addition to the first section of the raw material pneumatic conveying pipeline 2. When multiple sections of pipelines are connected, preferably, the outlet end of the previous pipeline is extended into the inlet end of the next pipeline and a non-contact sealing sleeve is performed, and an inflation pipe is provided at the sealing sleeve to prevent the material from flowing back into the previous pipeline. Non-contact sealing sleeve means that the previous pipeline and the next pipeline are in indirect contact through other components, not direct contact. More preferably, the structure of the non-contact sealing sleeve includes a first bellows 16 and a sleeve 17, the sleeve 17 is sleeved on the outer surface of the outlet end of the previous pipeline and extends to the outer surface of the inlet end of the next pipeline, the first bellows 16 is sleeved outside the sleeve 17 and the two ends extend outward respectively, and one end of the first bellows 16 is sleeved on the outer surface of the previous pipeline and the other end is sleeved on the outer surface of the next pipeline, and the inflation pipe is provided on the end face of the first bellows 16 close to the previous pipeline. Further preferably, the radial dimensions of the two end faces of the first bellows 16 and the sleeve 17 are different.

[0088] In some preferred embodiments, reference Figure 1 ( Figure 1 The arrow in the lower center indicates the direction of flow, and the arrow above indicates the direction of lifting and rotating. The growth furnace of the present invention also includes a lifting shaft 18, a lifting drive mechanism, and a first rotating drive mechanism. One end of the lifting shaft 18 extends into the furnace body and is sealed and rotatably connected to the crucible 1 and fixedly mounted on the seed crystal mounting portion 14. The other end of the lifting shaft extends outside the furnace body and is respectively connected to the lifting drive mechanism and the first rotating drive mechanism. The use of the lifting shaft and lifting drive mechanism to control the lifting of the seed crystal and its crystal allows the crystal to slowly move upward as it continues to thicken, keeping the crystal's growth interface unchanged, ensuring the temperature gradient between the crystal and the raw material, and obtaining silicon carbide crystals with uniform internal quality.

[0089] In the second aspect, the present invention provides a method for growing silicon carbide crystals, which is carried out in the silicon carbide crystal growth furnace for pneumatically conveying raw materials as described in the first aspect, and the method for growing silicon carbide crystals includes: heating the crucible 1 to the sublimation temperature of the raw materials, pneumatically conveying the raw materials into the crucible 1 through the first section raw material pneumatic conveying pipe 2, the sublimation gas generated by the sublimation of the raw materials flows through the tortuous logistics channel formed by the first graphite guide plate 3 and the second graphite guide plate 4 and then flows to the top of the crucible 1, the inclined graphite guide plate guides part of the logistics flowing out of the outlet of the first section raw material pneumatic conveying pipe 2 to flow downward toward the graphite deflector 5, and the airflow returns after the logistics flows to the graphite deflector 5, and the solid raw material falls into the lower part of the crucible 1.

[0090] The growth method of the present invention does not require pre-addition of raw materials into a crucible during growth of silicon carbide crystals. The crucible is heated to a sublimation temperature of the raw materials, and the raw materials are pneumatically conveyed into the crucible through a raw material pneumatic conveying pipe. The pneumatically conveyed raw materials can fully sublime and quickly condense into crystals at the seed crystal. By continuously pneumatically conveying the raw materials into the crucible, large-sized, high-quality crystals can be grown.

[0091] In some preferred embodiments, after some raw material particles flow out of the second-section raw material pneumatic conveying pipe 12, they fall onto the orifice plate 10 built into the first-section raw material pneumatic conveying pipe 2. An inert gas is passed through the aeration pipe at the bottom of the first-section raw material pneumatic conveying pipe 2. The inert gas sequentially flows through the baffle 11 built into the first-section raw material pneumatic conveying pipe 2 and the orifice plate 10. Raw material particles cannot be located below the baffle 11, so that the raw material particles on the orifice plate 10 leave the orifice plate 10, flow through the first-section raw material pneumatic conveying pipe 2, and then enter the crucible 1. This preferred solution is more conducive to fully utilizing the raw materials and preventing raw material particles from clogging the aeration pipe.

[0092] In some preferred embodiments, the raw materials are loaded into the feeding tank 1301, the vacuum degree in the feeding tank 1301 is adjusted to be the same as the vacuum degree of the working chamber where the crucible 1 is located, the spiral feeding piece 1302 is controlled to drive the raw materials to move downward, and inert gas is introduced into the feeding tank 1301 through the air supply pipe 1303. The inert gas is introduced into the ventilation channel of the spiral feeding piece 1302 through the inflation pipe on the feeding tank 1301. The inert gas is ejected through the air holes to accelerate the raw materials to move downward into the raw material pneumatic conveying pipe. Gas is supplied to the raw material pneumatic conveying pipe through at least one inflation pipe connected to the raw material pneumatic conveying pipe. Under the action of the pressure difference between the crucible 1 and the feeding tank 1301, the raw materials are pneumatically conveyed into the crucible 1.

[0093] In some preferred embodiments, the particle size of the pneumatically conveyed raw material is 2mm-5mm; and / or the ratio of the atomic percentage of silicon to the atomic percentage of carbon in the pneumatically conveyed raw material is 0.95~0.995. Under this preferred embodiment, the particle size of the pneumatically conveyed raw material is not less than 2mm, which is more conducive to preventing the sublimation gas from carrying raw materials that have not had time to sublimate to the seed crystal, forming crystal defects and affecting the crystal quality. The particle size is not greater than 5mm, which is more conducive to the smooth progress of the pneumatic conveying process. The ratio of the atomic percentage of silicon to the atomic percentage of carbon in the pneumatically conveyed raw material is 0.95~0.995, slightly lower than 1, which is more conducive to keeping the Si / C atomic ratio in the growth atmosphere in the crucible close to 1.0, reducing crystal defects, improving crystal quality, and suppressing excess C from adhering to accessories such as heaters and crucibles, avoiding the need to replace and clean accessories such as heaters for each growth furnace and damaging accessories, which can improve production efficiency and increase the service life of various components.

[0094] In some specific embodiments of the present invention, a method for growing silicon carbide crystals, such as Figures 1 to 5 The silicon carbide crystal growth furnace shown is carried out ( Figure 2 、 4 and 5 indicate the direction of logistics flow), including: heating the crucible 1 to the sublimation temperature of the raw material, loading the raw material into the feeding tank 1301, adjusting the vacuum degree in the feeding tank 1301 to be the same as the vacuum degree of the working chamber where the crucible 1 is located, controlling the spiral feeding member 1302 to drive the raw material to move downward, introducing inert gas into the feeding tank 1301 through the gas supply pipe 1303, introducing inert gas into the ventilation channel of the spiral feeding member 1302 through the inflation pipe on the feeding tank 1301, and ejecting the inert gas through the air hole to accelerate the raw material to move downward into the second section raw material pneumatic conveying pipe 12, and the raw material flows out of the second section raw material pneumatic conveying pipe 12 and enters the first section raw material pneumatic conveying pipe 2, and pneumatically conveys the raw material to the crucible 1 through the first section raw material pneumatic conveying pipe 2. The sublimation gas generated by the sublimation of the raw material flows through the tortuous logistics channel formed by the first graphite guide plate 3 and the second graphite guide plate 4 and the secondary first graphite guide plate 6 and the secondary second graphite guide plate 7. After passing through the tortuous logistics channel, it flows to the top of the crucible 1 through the perforated graphite plate 9. The inclined graphite guide plate guides part of the logistics flowing out of the outlet of the first section raw material pneumatic conveying pipe 2 to flow downward to the first graphite baffle 501 and the second graphite baffle 502. After the logistics flows to the first graphite baffle 501 and the second graphite baffle 502, the air flow returns, and the solid raw material falls into the lower part of the crucible 1 and further sublimates. Among them, part of the raw material particles flow out of the second section raw material pneumatic conveying pipe 12 and fall on the orifice plate 10 built into the first section raw material pneumatic conveying pipe 2. The inflation pipe at the bottom of the first section raw material pneumatic conveying pipe 2 is filled with inert gas, and the inert gas flows through the baffle 11 built into the first section raw material pneumatic conveying pipe 2 and the orifice plate 10 in turn. The raw material particles cannot be located below the baffle 11, so that the raw material particles on the orifice plate 10 leave the orifice plate 10 and flow through the first section raw material pneumatic conveying pipe 2 and enter the crucible 1.

[0095] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A silicon carbide crystal growth furnace with pneumatically conveyed raw materials, characterized in that: include: The crucible (1) is arranged in the furnace body, and an opening is provided at the center of the bottom thereof, and the edge of the opening extends vertically upward to form a sleeve (101); a first section of a raw material pneumatic conveying pipeline (2), which is vertically arranged, extending from the bottom center of the crucible (1) through the sleeve (101) into the crucible (1), and is sealedly connected to the sleeve (101); a first graphite guide plate (3) covering and sealing the upper end of the first section of the raw material pneumatic conveying pipe (2), an edge of which extends to the outside of the first section of the raw material pneumatic conveying pipe (2) and a gap is left between the edge and the inner wall of the crucible, an outlet of the first section of the raw material pneumatic conveying pipe (2) is located below the first graphite guide plate (3) and above the sleeve (101), and the outlet is arranged along the circumference of the first section of the raw material pneumatic conveying pipe (2); A second graphite guide plate (4), one end of which is fixed to the inner wall of the crucible, and the other end of which is suspended near the edge of the first graphite guide plate (3), and the suspended end and the edge of the first graphite guide plate (3) are arranged in a zigzag manner to form a zigzag flow channel; An inclined graphite guide plate, one end of which is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline (2), and the other end of which is suspended in the air, with the height of the fixed end being higher than the height of the suspended end; A graphite baffle (5) having one end fixed to the inner wall of the crucible or the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipe (2), and the other end suspended in the air, with the height of the fixed end being higher than the height of the suspended end. The inclined graphite guide plate guides part of the flow flowing out of the outlet to flow downward toward the graphite baffle (5), and the flow is turned back after flowing toward the graphite baffle (5), and the solid raw material falls into the lower part of the crucible (1); The edge of the first graphite guide plate (3) is provided with a first protrusion (301) surrounding the circumference of the first graphite guide plate (3), and the suspended end of the second graphite guide plate (4) is provided with a second protrusion (401) arranged in a staggered manner opposite to the first protrusion (301), and the first protrusion (301) and the second protrusion (401) are staggered in a staggered manner opposite to each other to form an S-shaped tortuous logistics channel.

2. The growth furnace according to claim 1, wherein: Also includes: a second first graphite guide plate (6) fixedly arranged on the upper surface of the first graphite guide plate (3) along the circumference of the first graphite guide plate (3), with a gap between its edge and the inner wall of the crucible, and at least two third protrusions (601) arranged on its edge and surrounding the circumference of the second first graphite guide plate (6); The second graphite guide plate (7) has one end fixed on the inner wall of the crucible and the other end suspended near the edge of the first graphite guide plate (6), and at least two fourth protrusions (701) are provided on the suspended end, and at least two of the fourth protrusions (701) and at least two of the third protrusions (601) are staggered relative to each other to form an S-shaped tortuous flow channel.

3. The growth furnace according to claim 2, wherein: The edge of the first graphite guide plate (3) is located below the suspended end of the second graphite guide plate (4), and the edge of the second first graphite guide plate (6) is located below the suspended end of the second second graphite guide plate (7); The first protrusion (301) and the third protrusion (601) are respectively located on the upper surface of the edge of the first graphite guide plate (3) and the upper surface of the edge of the second-first graphite guide plate (6), and the second protrusion (401) and the fourth protrusion (701) are respectively located on the lower surface of the suspended end of the second graphite guide plate (4) and the lower surface of the suspended end of the second-second graphite guide plate (7).

4. The growth furnace according to claim 1, wherein: The inclined graphite guide plate includes a structure of the first graphite guide plate (3) extending outside the first section of the raw material pneumatic conveying pipeline (2), and the height of the position where the first graphite guide plate (3) is fixedly connected to the outer wall of the first section of the raw material pneumatic conveying pipeline (2) is higher than the height of the edge.

5. The growth furnace according to claim 4, characterized in that It comprises an inclined graphite guide plate located below the first graphite guide plate (3), with its suspended end extending vertically downward; The graphite baffle (5) includes a first graphite baffle (501) and a second graphite baffle (502), one end of the first graphite baffle (501) is fixed on the outer wall of the sleeve or the outer wall of the first section of the raw material pneumatic conveying pipeline (2), and the other end of the first graphite baffle (501) is suspended, one end of the second graphite baffle (502) is fixed on the inner wall of the crucible, and the other end of the second graphite baffle (502) is suspended.

6. The growth furnace according to claim 1, wherein: The interior of the first section of the raw material pneumatic conveying pipeline (2) is sheathed with an infrared temperature measuring tube (8), the upper end of the infrared temperature measuring tube (8) is higher than the upper end of the first section of the raw material pneumatic conveying pipeline (2), the first graphite guide plate (3) is fixedly arranged on the outer wall of the infrared temperature measuring tube (8) and is arranged along the circumference of the infrared temperature measuring tube (8), the top outer surface of the infrared temperature measuring tube (8) is sheathed with a perforated graphite plate (9), the gas flows upward through the perforated graphite plate (9), and the solid raw material cannot flow upward through the perforated graphite plate (9), the perforated graphite plate (9) divides the crucible into an upper chamber and a lower chamber, the top of the upper chamber has a seed crystal mounting portion (14), the first graphite guide plate (3), the second graphite guide plate (4), the inclined graphite guide plate and the graphite deflector (5) are all located in the lower chamber.

7. The growth furnace according to claim 6, characterized in that A horizontal orifice plate (10) and a baffle (11) are built into the lower portion of the first section of the raw material pneumatic conveying pipeline (2), and the baffle (11) is located below the orifice plate (10); The growth furnace further comprises a second section of raw material pneumatic conveying pipe (12), which is connected to the side wall of the lower part of the first section of raw material pneumatic conveying pipe (2) and the connection position is located above the orifice plate (10). The bottom of the first section of raw material pneumatic conveying pipe (2) is connected to an inflation pipe, and the gas passes through the baffle (11) and the orifice plate (10) in sequence and flows through the first section of raw material pneumatic conveying pipe (2). Raw material particles cannot be located below the baffle (11).

8. The growth furnace according to claim 7, characterized in that The baffle (11) comprises: A first baffle (1101) is fixedly mounted on the outer wall of the infrared temperature measuring tube (8), with a gap between its edge and the inner wall of the first section of the raw material pneumatic conveying pipeline (2); The second baffle (1102) has one end fixedly arranged on the inner wall of the first section of the raw material pneumatic conveying pipeline (2), and the other end thereof is suspended near the edge of the first baffle (1101), and the suspended end is arranged close to the edge of the first baffle (1101) in a zigzag manner to form a zigzag flow channel.

9. The growth furnace according to claim 8, characterized in that The edge of the first baffle (1101) is provided with a protrusion (1103) surrounding the circumference of the first baffle (1101), and the suspended end of the second baffle (1102) has a protrusion (1103) arranged in a staggered manner relative to the protrusion (1103) on the first baffle (1101), and the protrusion (1103) on the first baffle (1101) and the protrusion (1103) on the second baffle (1102) are arranged in a staggered manner relative to each other to form an S-shaped tortuous logistics channel.

10. The growth furnace according to claim 1, wherein The device further comprises a feeding device (13), the feeding device comprising a feeding tank (1301) and a spiral feeding member (1302), the feeding tank (1301) being provided with an air supply pipe (1303), the spiral feeding member (1302) being provided in the feeding tank (1301) and extending along the central axis of the feeding tank (1301) for spiral feeding; The feeding tank (1301) is provided with an air filling pipe, the spiral feeding piece (1302) has an air vent, the air vent is connected to a plurality of air holes, and the air holes are distributed along the axial direction of the spiral feeding piece (1302), the air filling pipe on the feeding tank (1301), the air vent and the air holes are connected, the bottom outlet of the feeding tank (1301) is connected to the raw material pneumatic conveying pipe including the first section of the raw material pneumatic conveying pipe (2), and the raw material pneumatic conveying pipe is connected to at least one air filling pipe.

11. A method for growing silicon carbide crystals, characterized in that: It is carried out in a growth furnace for silicon carbide crystals with pneumatically conveyed raw materials as described in any one of claims 1 to 10, and the growth method of silicon carbide crystals comprises: heating a crucible (1) to a sublimation temperature of the raw materials, pneumatically conveying the raw materials into the crucible (1) through a first section of a raw material pneumatic conveying pipe (2), the sublimation gas generated by the sublimation of the raw materials flows through a tortuous flow channel formed by a first graphite guide plate (3) and a second graphite guide plate (4) and then flows to the top of the crucible (1), the inclined graphite guide plate guides part of the flow flowing out of the outlet of the first section of the raw material pneumatic conveying pipe (2) to flow downward to the graphite deflector (5), the flow flows to the graphite deflector (5) and then the airflow returns, and the solid raw material falls into the lower part of the crucible (1).

12. The growth method according to claim 11, characterized in that After some raw material particles flow out of the second section raw material pneumatic conveying pipe (12), they fall onto the orifice plate (10) built into the first section raw material pneumatic conveying pipe (2). The inflation pipe at the bottom of the first section raw material pneumatic conveying pipe (2) is filled with inert gas, and the inert gas flows through the baffle plate (11) built into the first section raw material pneumatic conveying pipe (2) and the orifice plate (10) in sequence. The raw material particles cannot be located below the baffle plate (11), so that the raw material particles on the orifice plate (10) leave the orifice plate (10) and flow through the first section raw material pneumatic conveying pipe (2) and enter the crucible (1).

13. The growth method according to claim 11, characterized in that The raw materials are loaded into a feeding tank (1301), the vacuum degree in the feeding tank (1301) is adjusted to be the same as the vacuum degree in the working chamber where the crucible (1) is located, the spiral feeding member (1302) is controlled to drive the raw materials to move downward, an inert gas is introduced into the feeding tank (1301) through the gas supply pipe (1303), the inert gas is introduced into the ventilation channel of the spiral feeding member (1302) through the gas filling pipe on the feeding tank (1301), the inert gas is ejected through the air holes, and the raw materials are accelerated to move downward into the raw material pneumatic conveying pipe, gas is supplied to the raw material pneumatic conveying pipe through at least one gas filling pipe connected to the raw material pneumatic conveying pipe, and the raw materials are pneumatically conveyed into the crucible (1) under the action of the pressure difference between the crucible (1) and the feeding tank (1301).

14. The growth method according to claim 11, characterized in that The particle size of the pneumatically conveyed raw material is 2 mm to 5 mm; and / or the ratio of the atomic percentage of silicon to the atomic percentage of carbon in the pneumatically conveyed raw material is 0.95 to 0.995.

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