Growth furnace and growth method for silicon carbide crystals capable of pneumatically conveying raw materials

Abstract

The invention belongs to the technical field of silicon carbide crystal growth, and particularly relates to a silicon carbide crystal growth furnace and growth method for pneumatically conveying raw materials. The growth furnace comprises a raw material pneumatic conveying pipeline entering the crucible from the bottom; the first guide plate covers and seals the upper end of the conveying pipeline, the edge of the first guide plate extends out of the conveying pipeline, a gap is reserved between the edge of the first guide plate and the inner wall of the crucible, and an outlet of the conveying pipeline is located below the first guide plate; one end of the second guide plate is fixed on the inner wall of the crucible, and the other end of the second guide plate is zigzag, close to the edge of the first guide plate and suspended; one end of the inclined guide plate is fixed on the outer wall of the conveying pipeline, and the other end is suspended; one end of the baffle plate is fixed on the inner wall of the crucible or the outer wall of the conveying pipeline, the other end of the baffle plate is suspended, and the inclined guide plate guides part of material flow flowing out of the outlet to flow downwards to the baffle plate; and the guide plates and the baffle plates are made of graphite. And growing large-size crystals by continuously conveying raw materials into the crucible.

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 method for SiC crystal growth is physical vapor transport (PVT). The principle is to load a certain amount of silicon carbide raw materials in a relatively closed crucible, and sublimate carbon powder and silicon powder at a high temperature of more than 2000℃ to decompose them into gas phase substances such as Si atoms, Si2C molecules and SiC2 molecules. Driven by the temperature gradient, these gas phase substances will be transported to the silicon carbide seed crystal with a lower temperature to form silicon carbide crystals. By controlling the temperature field, airflow and other process parameters of PVT, a specific 4H-SiC crystal type 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 growing silicon carbide crystal is subject to certain restrictions, 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 known technology. Summary of the invention

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

[0006] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a growth furnace for silicon carbide crystals with pneumatically conveyed raw materials, comprising: The crucible is arranged in the furnace body, and an opening is arranged at the center of the bottom thereof, and the edge of the opening vertically extends upward to form a sleeve; A first section of raw material pneumatic conveying pipeline is vertically arranged, extends from the bottom center of the crucible through the sleeve into the crucible, and is sealed and connected to the sleeve; A first graphite guide plate, which covers and seals the upper end of the first section of the raw material pneumatic conveying pipeline, and the 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, 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 arranged along the circumference of the first section of the raw material pneumatic conveying pipeline; A second graphite guide plate, one end of which is fixed on the inner wall of the crucible, and the other end of which is suspended near the edge of the first graphite guide plate, and the suspended end is zigzag near the edge of the first graphite guide plate 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, and the other end of which is suspended in the air, and the height of the fixed end is higher than the height of the suspended end; A graphite baffle, 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, 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 flow flowing out of the outlet to flow downward to the graphite baffle, and the airflow is turned back after the flow flows to the graphite baffle, and the solid raw material falls into the lower part of the crucible.

[0007] 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.

[0008] Preferably, it also includes: 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 surrounding the circumference of the second first graphite guide plate are arranged on its edge; 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, and at least two fourth protrusions are provided on the suspended end, and at least two of the fourth protrusions are staggered relative to at least two of the third protrusions to form an S-shaped tortuous logistics channel.

[0009] 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; 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.

[0010] 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.

[0011] Preferably, it comprises an inclined graphite guide plate located below the first graphite guide plate, and its suspended end extends vertically downward; 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.

[0012] 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 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 baffle are all located in the lower chamber.

[0013] Preferably, a horizontal orifice plate and a baffle are built into the lower part of the first section of the raw material pneumatic conveying pipeline, and the baffle is located below the orifice plate; 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.

[0014] Preferably, the baffle comprises: A first baffle, which is 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; The second baffle has one end fixedly disposed on the inner wall of the first section of the raw material pneumatic conveying pipeline, and the other end suspended near the edge of the first baffle, and the suspended end is zigzagly disposed near the edge of the first baffle to form a zigzag flow channel.

[0015] Preferably, the edge of the first baffle plate is provided with a protrusion surrounding the circumference of the first baffle plate, and the suspended end of the second baffle plate has a protrusion offset from the protrusion on the first baffle plate, and the protrusion on the first baffle plate and the protrusion on the second baffle plate are offset to form an S-shaped tortuous logistics channel.

[0016] 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 pipeline, the spiral feeding member is arranged in the feeding tank and extends along the central axis of the feeding tank for spiral feeding; The feeding tank is provided with an inflation pipe, the spiral feeding piece has a ventilation channel, the ventilation channel is connected with 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.

[0017] In a second aspect, the present invention provides a method for growing silicon carbide crystals, which is carried out in a growth furnace for silicon carbide crystals with pneumatically conveyed raw materials as described in the first aspect, and the method for growing silicon carbide crystals comprises: heating a crucible to a sublimation temperature of the raw materials, pneumatically conveying the raw materials into the crucible through a first section of a raw material pneumatic conveying pipeline, sublimation gas generated by the sublimation of the raw materials flows through a tortuous logistics channel formed by a first graphite guide plate and a second graphite guide plate and then flows to the top of the crucible, an inclined graphite guide plate guides part of the logistics flowing out of the outlet of the first section of the raw material pneumatic conveying pipeline to flow downward toward the graphite deflector, and the logistics flows to the graphite deflector and then the airflow turns back, and the solid raw material falls into the lower part of the crucible.

[0018] In some preferred embodiments, after part of the 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 sequence. 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.

[0019] In some preferred embodiments, the raw material is 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 material to move downward, and an inert gas is introduced into the feeding tank through an air supply pipe. An 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 material to move downward into the raw material pneumatic conveying pipe, and air 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 material is pneumatically conveyed into the crucible.

[0020] In some preferred embodiments, the particle size of the pneumatically conveyed raw material is 2 mm-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 0.95-0.995.

[0021] The silicon carbide crystal growth furnace for pneumatically conveying raw materials of the present invention comprises a crucible arranged in a furnace body, an opening is arranged at the bottom center of the crucible, a vertically arranged first section of raw material pneumatic conveying pipeline extends from the bottom center of the crucible into the crucible, and raw materials can be provided into the crucible by pneumatic conveying of inert gas; a first graphite guide plate covers and seals the upper end of the first section of raw material pneumatic conveying pipeline, an edge of the first graphite guide plate extends to the outside of the first section of raw material pneumatic conveying pipeline and a gap is left between the edge and the inner wall of the crucible, and the outlet of the first section of 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 in a zigzag manner to form a zigzag logistics channel. The zigzag 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 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 zigzag 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 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 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 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, the large-particle size raw material is guided by the inclined graphite guide plate to flow to the graphite baffle, and part of it 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 a small part that has not sublimated The raw material falls into the lower part of the crucible and is further sublimated and gasified, and can be fully sublimated; the guide plate and the baffle plate of the present invention are both made of graphite materials, and the guide plate and the baffle plate are heated at the same time as the inner and outer walls of the crucible are heated, which can promote the full sublimation of the raw material; when the silicon carbide crystal grows, there is no need to add the raw material into the crucible in advance, the crucible is heated to the sublimation temperature of the raw material, and the raw material is pneumatically conveyed into the crucible through the raw material pneumatic conveying pipeline, and the pneumatically conveyed raw material can be fully sublimated and quickly condensed into crystals at the seed crystal, and large-sized, high-quality crystals can be grown by continuously pneumatically conveying the raw material into the crucible. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1It is a structural schematic diagram of a specific embodiment of a growth furnace for silicon carbide crystals with pneumatically conveyed raw materials of the present invention; Figure 2 It is a partial structural schematic diagram of a specific implementation method of the coordination between the feeding device and the raw material pneumatic conveying pipeline of the present invention; Figure 3 It is a partial structural schematic diagram of a specific implementation mode of the crucible of the present invention cooperating with the first section of the raw material pneumatic conveying pipeline; Figure 4 It is a partial structural schematic diagram of a specific implementation method of 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; Figure 5 yes Figure 4 A partial enlarged view of the lower structure of the first section of the raw material pneumatic conveying pipeline.

[0024] Description of Reference Numerals 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. With hole Graphite plate; 10, orifice plate; 11, baffle; 1101, first baffle; 1102, second baffle; 1103, protrusion; 12, second section 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

[0025] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0026] 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.

[0027] 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 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, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0030] 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 gradient, 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.

[0031] 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 logistics), the present invention provides a growth furnace for silicon carbide crystals with pneumatic conveying of raw materials, comprising: The crucible 1 is arranged in the furnace body, and an opening is arranged at the center of the bottom thereof, and the edge of the opening extends vertically upward to form a sleeve 101; 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 to the crucible 1, and is sealed and connected to the sleeve 101; 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, and its edge extends to the outside of the first section of the raw material pneumatic conveying pipeline 2 and a gap is left between its edge and the inner wall of the crucible, and the 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; A second graphite guide plate 4, one end of which is fixed on 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 is zigzag near the edge of the first graphite guide plate 3 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, and the height of the fixed end is higher than the height of the suspended end; 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 pipeline 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 flow flowing out of the outlet to flow downward to the graphite baffle 5. After the flow flows to the graphite baffle 5, the airflow is turned back, and the solid raw material falls into the lower part of the crucible 1.

[0032] The growth furnace of 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 raw material pneumatic conveying pipeline extends from the bottom center of the crucible into the crucible, and raw materials can be provided to the crucible by 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 and connected to the sleeve, and the first raw material pneumatic conveying pipeline and the crucible can be conveniently sealed and connected.

[0033] The growth furnace of the present invention comprises a first guide plate which covers and seals 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 on 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 circumferential arrangement of the pneumatic conveying pipeline for the material heats the crucible 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 arrangement of the tortuous logistics channel can prevent the sublimation gas from carrying small-grained raw materials that have not had time to sublimate to the seed crystal or crystal, thereby affecting the quality of the crystal. The graphite guide plate is made of graphite and is also heated. The temperature of the guide plate can meet the volatilization temperature of the raw material, and the small-grained raw materials that have not had time to sublimate and fall into the tortuous logistics channel will further sublime.

[0034] 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 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 in the air, and the height of the fixed end is higher than the height of the suspended end. By setting the inclined graphite guide plate and the graphite baffle, the large-particle size raw material is guided by the inclined graphite guide plate to flow to the graphite baffle, 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. The small amount of raw material that has not sublimated falls into the lower part of the crucible for further sublimation, and can be fully sublimated.

[0035] 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, and 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 large-particle raw material is guided by the inclined graphite guide plate to flow to the graphite baffle plate, and partially sublimates in the process of flowing to the graphite baffle plate. The sublimation gas rebounds and returns after flowing to the graphite baffle plate, and a small amount of raw material that has not sublimated falls into the lower part of the crucible for further sublimation. The sublimation gas is effectively separated from the part of the raw material that has not sublimated, and the gas condenses upward into crystals, and the solid particles have sufficient time to be heated and sublimated.

[0036] The guide plate and the baffle plate of the present invention are both made of graphite. When the inner and outer walls of the crucible are heated, the guide plate and the baffle plate are also heated at the same time according to the heat conduction and heat radiation principles of the material, which can promote the full and rapid sublimation of the raw materials. The heating of the guide plate and the baffle plate makes the temperature in the crucible more uniform, which can avoid the raw materials in the low temperature area from not fully sublimating and the raw materials in the high temperature area from carbonizing, which affects the crystal quality.

[0037] The growth furnace of the present invention does not need to add raw materials in advance to the crucible when growing silicon carbide crystals. 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 and quickly 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. The growth furnace of the present invention continuously adds materials during the crystal growth process, and grows crystals while adding materials. A crucible with a smaller height can be used for crystal growth, and the crucible cost can be reduced while growing large-sized crystals.

[0038] The present invention does not limit the sealing connection method between the first section of the raw material pneumatic conveying pipeline and the sleeve, and specifically, for example, a threaded connection can be used. The crucible of the present invention includes a crucible wall that circumferentially surrounds the crucible, and 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, and the outer wall of the sleeve refers to the wall of the sleeve that is not in contact with the outer wall of the first section of the raw material pneumatic conveying pipeline.

[0039] It can be understood that the crucible of the present invention has a gap through which the 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.

[0040] 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 a plurality of second graphite guide plates distributed along the circumference of the inner wall of the crucible. It is preferably 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, thereby affecting the crystal quality.

[0041] The suspended end of the second graphite guide plate of the present invention is arranged close to the edge of the first graphite guide plate in a tortuous manner to form a tortuous logistics channel. The present invention does not limit the form of the tortuous close arrangement. In some preferred schemes, 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 opposite to the first protrusion 301, and the first protrusion 301 and the second protrusion 401 are arranged opposite to each other to form an S-shaped tortuous logistics channel. Under this preferred scheme, it is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not sublimated in time to reach the crystal or seed crystal, 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 may be located below the suspended end of the second graphite guide plate 4, or the edge of the first graphite guide plate 3 may be located above the suspended end of the second graphite guide plate 4. The first protrusion 301 and the second protrusion 401 are arranged opposite to 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, 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, Convex downward, for 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, 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, 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, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to the seed crystal and crystal, affecting the crystal quality. The staggered setting refers to that the protrusion directions of the first protrusion 301 and the second protrusion 401 are staggered and not in a straight line.

[0042] 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 arranged on its edge; 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 are staggered relative to at least two of the third protrusions 601 to form an S-shaped tortuous logistics channel.

[0043] Under this preferred embodiment, a sub-first graphite guide plate 6 with a gap between its edge and the inner wall of the crucible is arranged on the upper surface of the first graphite guide plate along the circumference of the first graphite guide plate 3, a third protrusion 601 surrounding the circumference of the sub-first graphite guide plate is arranged on the edge of the sub-first graphite guide plate 6, a sub-second graphite guide plate 7 is arranged 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 arranged on the suspended end of the sub-second graphite guide plate 7 and is offset from the third protrusion 601, and 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 crystal quality. 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 arranged to be 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 position 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 is located below the suspended end of the sub-second graphite guide plate 7, or the edge of the sub-first graphite guide plate 6 is 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 opposite to 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 at the lower surface of the edge of the second first graphite guide plate 6, that is, convex downward, and the fourth protrusion 701 of the second second graphite guide plate 7 is located at 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, which is more conducive to preventing the sublimation gas from carrying small-particle raw materials that have not sublimated in time to the seed crystal or crystal, affecting the crystal quality. The staggered setting refers to the alternating setting 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 in a straight line.

[0044] The secondary 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 secondary second graphite guide plate, or it can have several secondary second graphite guide plates distributed along the circumference of the inner wall of the crucible. It is preferably an annular secondary 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, thereby affecting the crystal quality.

[0045] The structure of the first graphite guide plate of the present invention extending outside the first section of the raw material pneumatic conveying pipeline 2 can be arranged inclined or horizontally. In some preferred embodiments, the inclined graphite guide plate includes the 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. Under this preferred embodiment, the first graphite guide plate can simultaneously prevent the sublimation gas from carrying small-particle raw materials that have not had time to sublimate to the seed crystal or crystal, affecting the crystal quality, and guide the large-particle raw materials to flow to the graphite baffle.

[0046] The present invention may 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; 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.

[0047] 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 arranged below the first graphite guide plate 3. By arranging two inclined graphite guide plates, it is more conducive to guiding the large-particle raw materials to flow to the graphite baffle plate. The suspended end of the inclined graphite guide plate below the first graphite guide plate 3 extends vertically downward. The graphite baffle plate 5 includes a first graphite baffle plate 501 and a second graphite baffle plate 502. One end of the first graphite baffle plate 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. 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 a part of the flow to the first graphite baffle 501, and the other part of the flow 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 outlets 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 to guide the airflow diversion to move downward, which is more conducive to the sublimation of solid particles in the raw material.

[0048] 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 arranged along the circumference of the infrared temperature measuring tube 8, and a perforated graphite plate 9 is sheathed on the outer surface of the top end of the infrared temperature measuring tube 8, 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 baffle 5 are all located in the lower chamber.

[0049] Under this preferred embodiment, by setting an infrared temperature measuring tube, the temperature of the crystal surface can be measured, the growth rate can be calculated, and the conveying speed and weight of the raw material can be controlled, so as to form a closed-loop control on the crystal growth process, so that the temperature difference between the crystal growth interface and the raw material surface remains relatively constant, the crystal growth interface is maintained stable, and silicon carbide crystals with uniform internal quality are obtained. 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.

[0050] Preferably, a horizontal orifice plate 10 and a baffle plate 11 are built into the lower part of the first section of the raw material pneumatic conveying pipeline 2, and the baffle plate 11 is located below the orifice plate 10; The growth furnace also includes a second section of raw material pneumatic conveying pipeline 12, which is connected to the side wall of the lower part of the first section of raw material pneumatic conveying pipeline 2 and the connection position is located above the orifice plate 10. The bottom of the first section of raw material pneumatic conveying pipeline 2 is connected to an inflation pipeline, 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 pipeline 2, and the raw material particles cannot be located below the baffle 11.

[0051] This preferred embodiment 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 the 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 with an inflation pipeline. After the raw material comes out of the second section of the raw material pneumatic conveying pipeline, some particles with large mass fall on the orifice plate. The inflation pipeline connected to the bottom of the first section of the raw material pneumatic conveying pipeline is passed with inert gas, which can make the raw material particles on the orifice plate 10 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 plate 11 is arranged below the orifice plate 10, and the gas passes through the baffle plate 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 plate 11, which is more conducive to avoiding the raw material particles from clogging the inflation pipeline.

[0052] Preferably, the second-section raw material pneumatic conveying pipeline 12 is connected to one side of the first-section raw material pneumatic conveying pipeline 2, and an observation window 15 is provided on the side of the first-section raw material pneumatic conveying pipeline 2 away from the second-section raw material pneumatic conveying pipeline 12. The observation window 15 and the second-section raw material pneumatic conveying pipeline 12 are located on opposite sides of the first-section raw material pneumatic conveying pipeline 2, which is more conducive to observing the flow of raw materials.

[0053] 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, and a gap is left between its edge and the inner wall of the first section of the raw material pneumatic conveying pipeline 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 pipeline 2, and the other end of which is suspended near the edge of the first baffle 1101, and its suspended end is arranged close to the edge of the first baffle 1101 to form a tortuous flow channel. The baffle form under this preferred scheme is more conducive to blocking raw material particles and preventing raw material particles from clogging the inflation pipeline. The second baffle of the present invention can be arranged along the circumference of the inner wall of the first section of the pneumatic conveying pipeline 2 of the raw material. It can be an annular second baffle, or it can have a plurality of second baffles distributed along the circumference of the inner wall of the first section of the pneumatic conveying pipeline of the raw material. It is preferably an annular second baffle arranged along the circumference of the inner wall of the first section of the pneumatic conveying pipeline of the raw material, which is more conducive to blocking the raw material particles and preventing the raw material particles from clogging the inflation pipeline. Preferably, 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 opposite 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 opposite to each other to form an S-shaped tortuous logistics channel. The baffle form under this preferred scheme is more conducive to blocking the raw material particles and preventing the raw material particles from clogging the inflation pipeline. 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 protrusion on the first baffle and the protrusion 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 arrangement 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.

[0054] The lower end of the heating part outside 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 full and rapid sublimation of the raw materials transported by pneumatic force.

[0055] 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 pipeline 1303. The spiral feeding member 1302 is arranged in the feeding tank 1301 and extends along the central axis of the feeding tank 1301 to feed in a spiral manner. 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 with 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 raw material pneumatic conveying pipeline 2, and at least one inflation pipe is connected to the raw material pneumatic conveying pipeline.

[0056] 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 help promote the raw material to completely reach the crucible and is more conducive to preventing the material from falling or flowing back.

[0057] Preferably, the spiral feeding member 1302 includes a rotating shaft and blades, the blades are spirally wrapped around 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 holes are arranged 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.

[0058] The raw material pneumatic conveying pipeline of the present invention may include multiple sections of raw material pneumatic conveying pipelines other than 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 pipeline is arranged 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 indirectly contacted through other components, not directly. 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 pipeline is arranged on the end surface 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.

[0059] In some preferred embodiments, reference Figure 1 ( Figure 1 The arrow in the middle and lower part indicates the flow direction of the logistics, and the arrow above indicates the lifting direction and the rotation direction). The growth furnace of the present invention also includes a lifting shaft 18, a lifting drive mechanism, and a first rotation 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 out of the furnace body and is connected to the lifting drive mechanism and the first rotation drive mechanism respectively. The lifting shaft and the lifting drive mechanism are used to control the lifting of the seed crystal and its crystal, so that as the crystal continues to thicken, the crystal can also move slowly upward, keep the growth interface of the crystal unchanged, ensure the temperature gradient between the crystal and the raw material, and obtain silicon carbide crystals with uniform internal quality.

[0060] In the second aspect, the present invention provides a method for growing silicon carbide crystals, which is carried out in the growth furnace of silicon carbide crystals with pneumatically conveyed raw materials as described in the first aspect, and the method for growing silicon carbide crystals comprises: 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 pipeline 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 pipeline 2 to flow downward to the graphite deflector 5, and the airflow turns back after the logistics flows to the graphite deflector 5, and the solid raw material falls into the lower part of the crucible 1.

[0061] The growth method of the present invention does not require the addition of raw materials into a crucible in advance during the growth of silicon carbide crystals. The crucible is heated to the sublimation temperature of the raw materials, and the raw materials are pneumatically conveyed into the crucible through a raw material pneumatic conveying pipeline. The pneumatically conveyed raw materials can be fully sublimated and quickly condensed into crystals at the seed crystal. Large-sized, high-quality crystals can be grown by continuously pneumatically conveying the raw materials into the crucible.

[0062] In some preferred embodiments, after some raw material particles flow out of the second section raw material pneumatic conveying pipeline 12, they fall onto the orifice plate 10 built into the first section raw material pneumatic conveying pipeline 2. The gas filling pipeline at the bottom of the first section raw material pneumatic conveying pipeline 2 is passed with inert gas, and the inert gas flows through the baffle plate 11 built into the first section raw material pneumatic conveying pipeline 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 pipeline 2 and then enter the crucible 1. Under this preferred solution, it is more conducive to fully utilizing the raw materials and avoiding the raw material particles from clogging the gas filling pipeline.

[0063] In some preferred embodiments, the raw material is 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 material to move downward, and 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 piece 1302 through the inflation pipe on the feeding tank 1301. The inert gas is ejected through the air holes to accelerate the raw material to move downward into the raw material pneumatic conveying pipe, and 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 material is delivered into the crucible 1 by pneumatic conveying.

[0064] 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 scheme, 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 the raw material that has not had time to sublimate to the seed crystal, forming crystal defects and affecting the crystal quality. The particle size is not more 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 inhibiting excess C from adhering to accessories such as heaters and crucibles, avoiding the need to replace cleaned accessories such as heaters for each growth furnace and damaging accessories, which can improve production efficiency and increase the service life of each component.

[0065] In some specific embodiments of the present invention, a method for growing a silicon carbide crystal, in the following manner: Figure 1~Figure 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 the inert gas is ejected through the air holes 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 then enters the first section raw material pneumatic conveying pipe 2, and the raw material is pneumatically conveyed into the crucible 1 through the first section raw material pneumatic conveying pipe 2, and 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 second first graphite guide plate 6 and the second second graphite guide plate 7. The raw material flows through the tortuous flow channel and then flows to the top of the crucible 1 through the perforated graphite plate 9. The inclined graphite guide plate guides part of the flow flowing out from the outlet of the first section raw material pneumatic conveying pipeline 2 to flow downward to the first graphite baffle 501 and the second graphite baffle 502. After the flow flows to the first graphite baffle 501 and the second graphite baffle 502, the air flow turns back, 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 pipeline 12 and fall on the orifice plate 10 built into the first section raw material pneumatic conveying pipeline 2. The inflation pipe at the bottom of the first section raw material pneumatic conveying pipeline 2 is filled with inert gas. The inert gas flows through the baffle 11 built into the first section raw material pneumatic conveying pipeline 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 pipeline 2 and then enter the crucible 1.

[0066] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope 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 arranged 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 raw material pneumatic conveying pipeline (2), which is arranged vertically, extends 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) which covers and seals the upper end of the first section of the raw material pneumatic conveying pipeline (2), the edge of which extends to the outside of the first section of the raw material pneumatic conveying pipeline (2) and a gap is left between the edge and the inner wall of the crucible, the 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); 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 is arranged close to the edge of the first graphite guide plate (3) 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) has 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 pipeline (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 flow flowing out of the outlet to flow downward to the graphite baffle (5), and the flow flows to the graphite baffle (5) and then the airflow is turned back, so that the solid raw material falls into the lower part of the crucible (1).

2. The growth furnace according to claim 1, characterized in that: 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 an offset manner opposite to the first protrusion (301), and the first protrusion (301) and the second protrusion (401) are arranged in an offset manner opposite to each other to form an S-shaped tortuous flow channel.

3. The growth furnace according to claim 2, characterized in that: Also includes: A second 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 second first graphite guide plate (6) along the circumference of the first graphite guide plate (6) are arranged on its edge; A 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.

4. The growth furnace according to claim 3, characterized in that: 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).

5. The growth furnace according to claim 1, characterized in that: The inclined graphite guide plate comprises 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.

6. The growth furnace according to claim 5, characterized in that: It comprises an inclined graphite guide plate located below the first graphite guide plate (3), with a suspended end extending vertically downward; The graphite baffle (5) comprises 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), and the other end of the first graphite baffle (501) is suspended in the air, one end of the second graphite baffle (502) is fixed to the inner wall of the crucible, and the other end of the second graphite baffle (502) is suspended in the air.

7. The growth furnace according to claim 1, characterized in that: The first section of the raw material pneumatic conveying pipeline (2) is internally sleeved 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 sleeved 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 is provided with 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 baffle (5) are all located in the lower chamber.

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

9. The growth furnace according to claim 8, 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 disposed on the inner wall of the first section of the raw material pneumatic conveying pipeline (2), and the other end 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.

10. The growth furnace according to claim 9, characterized in that: The edge of the first baffle (1101) is provided with a protrusion (1103) which surrounds the circumference of the first baffle (1101), and the suspended end of the second baffle (1102) has a protrusion (1103) which is arranged offset to face 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 offset to face each other to form an S-shaped tortuous logistics channel.

11. The growth furnace according to claim 1, characterized in that: It also comprises a feeding device (13), the feeding device comprising a feeding tank (1301) and a spiral feeding piece (1302), the feeding tank (1301) being provided with an air supply pipeline (1303), the spiral feeding piece (1302) being arranged 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 with a plurality of air holes and the plurality of 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 with 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 with at least one air filling pipe.

12. A method for growing silicon carbide crystals, characterized in that: The method 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 11, and the growth method for 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 pipeline (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 pipeline (2) to flow downward to a graphite baffle (5), the flow flows to the graphite baffle (5) and then the gas flow is turned back, and the solid raw material falls into the lower part of the crucible (1).

13. The growth method according to claim 12, characterized in that: After some raw material particles flow out of the second section raw material pneumatic conveying pipeline (12), they fall onto the orifice plate (10) built into the first section raw material pneumatic conveying pipeline (2). An inert gas is passed through the gas filling pipeline at the bottom of the first section raw material pneumatic conveying pipeline (2). The inert gas flows through the baffle plate (11) built into the first section raw material pneumatic conveying pipeline (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), flow through the first section raw material pneumatic conveying pipeline (2), and then enter the crucible (1).

14. The growth method according to claim 12, characterized in that: The raw material is 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 piece (1302) is controlled to drive the raw material to move downward, an inert gas is introduced into the feeding tank (1301) through a gas supply pipe (1303), an inert gas is introduced into the gas passage of the spiral feeding piece (1302) through a gas charging pipe on the feeding tank (1301), the inert gas is ejected through the gas hole, and the raw material is accelerated to move downward into the raw material pneumatic conveying pipe, gas is supplied into the raw material pneumatic conveying pipe through at least one gas charging pipe connected to the raw material pneumatic conveying pipe, and the raw material is delivered into the crucible (1) by pneumatic conveying under the action of the pressure difference between the crucible (1) and the feeding tank (1301).

15. The growth method according to claim 12, characterized in that: The particle size of the pneumatically conveyed raw material is 2 mm-5 mm; and / or the ratio of the atomic percentage of silicon element to the atomic percentage of carbon element in the pneumatically conveyed raw material is 0.95-0.995.

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