Silicon carbide growth furnace capable of quantitative feeding and silicon carbide growth method

Abstract

The present invention belongs to the technical field of silicon carbide crystal growth, and specifically relates to a silicon carbide growth furnace and a silicon carbide growth method capable of quantitative feeding, comprising a furnace body and a crucible, a seed crystal mounting portion being provided at the top of the crucible, and a quantitative feeding device comprising a feeding tank, a spiral feeding device, and a feeding and conveying pipe; a feeding pipe is provided at the bottom of the crucible, and the feeding pipe extends from the bottom of the furnace body and the bottom of the crucible to the inside of the crucible from bottom to top, forming a raw material bin between the feeding pipe and the inner wall of the crucible; the upper portion of the feeding and conveying pipe is provided within the feeding pipe and extends to above the height of the raw material bin and is connected to the raw material bin for feeding. The present invention can continuously feed during the crystal growth process, which can not only increase the thickness of the growing crystal, but also improve the internal quality of the crystal.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon carbide crystal growth, and in particular relates to a silicon carbide growth furnace capable of quantitatively adding materials and a silicon carbide growth method. 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. At temperatures exceeding 2000°C, carbon powder and silicon powder sublimate and decompose 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 seed crystal to form silicon carbide crystals. By controlling the PVT process parameters such as the temperature field, specific 4H-SiC crystal forms can be grown.

[0003] Because the crucible holds a fixed volume of raw materials, the thickness of the grown SiC crystal is limited. Furthermore, after crystal growth is complete, the crucible, silicon carbide crystal, heater, and other components must be removed and the graphite components cleaned, which is time-consuming and labor-intensive, impacting production efficiency.

[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] Research has found that the atomic ratio of Si and C in the silicon carbide raw materials used in the industry is 1:1. At high temperatures, Si in the silicon carbide raw materials will evaporate preferentially. In the early stages of silicon carbide crystal growth, Si>C in the growth atmosphere. At this time, the gas phase components are usually silicon-rich, which is not conducive to crystal growth; in the middle stage of crystal growth, the Si / C ratio in the growth atmosphere is close to 1.0, which is suitable for the growth environment of silicon carbide crystals, and the atoms inside the crystals are relatively stable; in the late stage of crystal growth, Si<C in the growth atmosphere, and the unreacted raw materials become increasingly rich in C atoms, causing the Si / C atomic ratio in the gas phase in the late stage of crystal growth to become lower and lower. Excess C will be deposited on the crystal growth surface to form inclusions. Because the crucible volume is fixed in the existing technology, growth must be terminated when the raw material component ratio is seriously unbalanced. Therefore, the thickness of the silicon carbide crystal is small.

[0006] The purpose of the present invention is to overcome the defects of the prior art in growing silicon carbide crystals using the PVT method, such as the small thickness and limitations of the crystals, and to provide a silicon carbide growth furnace and a silicon carbide growth method that can add material in a quantitative manner. The furnace can continuously add material during the crystal growth process, thereby not only increasing the thickness of the crystal growth, but also improving the internal quality of the crystal.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a silicon carbide growth furnace capable of quantitative feeding, comprising a furnace body and a crucible, wherein a seed crystal mounting portion is provided on the top of the crucible, and further comprising a quantitative feeding device, wherein the quantitative feeding device comprises a feeding tank, a spiral feeding device, and a feeding and conveying pipeline; wherein an air supply pipeline and a vacuum pipeline are provided on the feeding tank;

[0008] The spiral feeding device includes a spiral member, the spiral member has a ventilation channel, and 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 member; the inlet of the ventilation channel is connected to a primary inflation pipe;

[0009] A feeding pipe is provided at the lower part of the crucible, and the feeding pipe extends from the bottom of the furnace body and the bottom of the crucible to the inside of the crucible from bottom to top, and a raw material bin is formed between the feeding pipe and the inner wall of the crucible; the upper part of the feeding and conveying pipe is arranged in the feeding pipe and extends to above the height of the raw material bin and is connected to the raw material bin for feeding; the side wall of the feeding and conveying pipe located outside the furnace body is sealedly connected to the furnace body, and the lower part of the feeding and conveying pipe has a side inlet and a bottom inlet; the bottom inlet is connected to a three-stage inflation pipe for introducing an inert gas carrier gas;

[0010] The side inlet is connected to the outlet of the feeding tank through an intermediate feeding pipe, and a first ball valve with controllable opening is provided at the outlet of the feeding tank; and when the intermediate feeding pipe is used to connect two or more pipes, the outlet end of the previous pipe is extended into the inlet end of the next pipe and a non-contact sealing connection is performed, and a secondary inflation pipe is provided at the sealing connection.

[0011] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes porous graphite, a first guide plate and a third guide plate. The porous graphite is located between the seed crystal mounting portion and the raw material bin and separates the two into an upper chamber and a lower chamber. The first guide plate and the third guide plate are both located in the lower chamber. The bottom of the first guide plate is fixed on the feeding and conveying pipe and a gap is left between its edge and the inner wall of the crucible. The outlet of the feeding and conveying pipe is located below the first guide plate, and the radial dimension of the first guide plate is larger than the radial dimension of the feeding and conveying pipe. One end of the third guide plate is fixed on the inner wall of the crucible and the other end is suspended close to the edge of the first guide plate. The suspended end of the third guide plate is arranged close to the edge of the first guide plate to form a tortuous logistics channel.

[0012] In some preferred embodiments of the present invention, the edge portion of the first guide plate is U-shaped, and the suspended end portion of the third guide plate extends vertically downward to the U-shaped portion of the first guide plate, forming a U-shaped tortuous logistics channel.

[0013] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes a second guide plate, which is sleeved on the outer surface of the feeding and conveying pipe and extends along the radial circumferential direction of the feeding and conveying pipe. The second guide plate is located below the top outlet of the feeding and conveying pipe and below the first guide plate. The lower end height of the second guide plate is lower than the upper end height of the second guide plate, and the lower end of the second guide plate extends at least to the top of an adjacent portion of the raw material bin.

[0014] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes a spacer sleeve arranged in the crucible, the spacer sleeve surrounds the outer surface of the corresponding feeding and conveying pipe and an evaporation and feeding gap is left between the two, the raw material bin is formed between the spacer sleeve and the inner wall of the crucible, and the material of the spacer sleeve is a porous material, so that the raw material in the raw material bin evaporates and enters the evaporation and feeding gap through the spacer sleeve; and the top of the feeding and conveying pipe is sealed and a feeding through hole is provided near the top, the feeding through holes are arranged along the radial circumferential direction of the feeding and conveying pipe, the feeding through holes are located between the first guide plate and the second guide plate, and the evaporation and feeding gap extends to between the top of the spacer sleeve and the second guide plate and continues to extend to the raw material bin.

[0015] In some preferred embodiments of the present invention, the upper portion of the second guide plate is umbrella-shaped, and the lower end of the umbrella extends vertically to above an adjacent portion of the raw material bin.

[0016] In some preferred embodiments of the present invention, the lower portion of the feeding and conveying pipeline is connected to the tertiary inflation pipeline and the intermediate feeding pipeline via an air slip ring, so that the inert gas carrier gas is introduced into the bottom inlet of the feeding and conveying pipeline through the tertiary inflation pipeline, and the material is fed from the intermediate feeding pipeline into the side inlet of the feeding and conveying pipeline.

[0017] In some preferred embodiments of the present invention, the radial dimension of the lower portion of the feeding tank gradually decreases from top to bottom.

[0018] In some preferred embodiments of the present invention, a perforated plate for blocking raw material particles is provided between the bottom inlet of the feeding and conveying pipeline and the tertiary aeration pipeline.

[0019] In some preferred embodiments of the present invention, the spiral member extends to near the outlet of the feeding tank.

[0020] In some preferred embodiments of the present invention, the spiral member includes a rotating shaft and blades, the blades are spirally wrapped around the part of the rotating shaft located in the feeding tank 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 first-level inflation pipe; the spiral feeding device also includes a rotating motor for driving the spiral member to rotate, the rotating motor is connected to the top of the rotating shaft and is located outside the feeding tank.

[0021] In some preferred embodiments of the present invention, a second ball valve capable of controlling the opening is provided near the outlet of the previous pipeline.

[0022] In some preferred embodiments of the present invention, the structure of the non-contact sealing sleeve includes a first bellows and a sleeve, the sleeve is sleeved on the outer surface of the outlet end of the previous pipe and extends to the outer surface of the inlet end of the subsequent pipe, the first bellows is sleeved outside the sleeve and both ends extend outward respectively, and one end of the first bellows is sleeved on the outer surface of the previous pipe and the other end is sleeved on the outer surface of the subsequent pipe, and the secondary inflation pipe is arranged on the end face of the first bellows close to the previous pipe. The first bellows can play a vacuum sealing role and also play a shock absorbing role. When the secondary inflation valve is opened, the gas will flow into the subsequent pipe along the sleeve, preventing the raw material from flowing into the first bellows, increasing the service life of the first bellows, and accelerating the fluidity of the material.

[0023] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding further includes a lifting shaft, a lifting drive mechanism, a first rotary drive mechanism, a first weighing device for weighing a feeding tank, and a second weighing device for weighing the seed crystal and the crystal grown therefrom. One end of the lifting shaft extends into the crucible and is sealed and rotatably connected to the crucible and fixedly mounted on the seed crystal mounting portion. The other end of the lifting shaft extends outside the furnace body and is respectively connected to the lifting drive mechanism and the first rotary drive mechanism. The first weighing device is mounted on the feeding tank, and the second weighing device is mounted on the portion of the lifting shaft located outside the furnace body. The feeding tank is equipped with a first weighing device that can accurately record the weight of the material flowing out of the feeding tank and can control the weight of the feeding with high precision.

[0024] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes a crucible support mechanism, a crucible lifting mechanism and a second rotary drive mechanism; wherein, the crucible support mechanism is installed below the crucible and is arranged on the outer surface of the feeding and conveying pipe through a bearing sleeve, and extends outward with the feeding and conveying pipe; the crucible lifting mechanism and the second rotary drive mechanism are respectively arranged on the outside of the furnace body, the crucible lifting mechanism is connected to the outwardly extending part of the crucible support mechanism and the connection is sealed with the furnace body by a second bellows, which is used to drive the crucible support mechanism to drive the crucible to lift and lower; the second rotary drive mechanism is connected to the outwardly extending part of the crucible support mechanism, which is used to control the rotation of the crucible.

[0025] In some preferred embodiments of the present invention, a first vacuum gauge is provided on the furnace body, and a second vacuum gauge is also provided on the feeding tank; a gas supply valve is provided on the gas supply pipe, a vacuum valve is provided on the vacuum pipe, a first-level gas charging pipe is provided with a first-level gas charging valve, a third-level gas charging pipe is provided with a third-level gas charging valve, and a second-level gas charging pipe is provided with a second-level gas charging valve; and the silicon carbide growth furnace capable of quantitative feeding also includes a PLC controller, which is electrically connected to the first-level gas charging valve, the third-level gas charging valve, the second-level gas charging valve, the first ball valve, the first vacuum gauge, the second vacuum gauge, and the gas supply valve, respectively.

[0026] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes an insulating shell, a heater, and an infrared pyrometer for detecting the temperature of the side of the seed crystal installed on the opposite side of the seed crystal mounting portion, the infrared pyrometer is located outside the furnace body and directly above the seed crystal, the insulating shell is located outside the crucible and the feeding pipe and is located inside the furnace body, the heater is located between the insulating shell and the crucible; and a vacuum outlet is provided on the side of the furnace body.

[0027] In a second aspect, the present invention provides a silicon carbide growth method, which is carried out in the silicon carbide growth furnace capable of quantitative feeding as described in the first aspect.

[0028] The silicon carbide growth method includes:

[0029] A first raw material is loaded into a raw material bin of a crucible in advance, and a second raw material is loaded into a feeding tank; wherein the carbon atom content of the first raw material is greater than the silicon atom content, and the carbon atom content of the second raw material is less than the silicon atom content; then the crucible is heated to grow silicon carbide crystals.

[0030] Among them, in the middle and / or late stages of crystal growth, feeding is carried out through a quantitative feeding device. Specifically, the vacuum degree in the feeding tank is first adjusted through the vacuum valve on the vacuum pipe to make it the same as the vacuum degree of the working chamber where the crucible is located; then the first ball valve is opened to make it at the target opening, and the spiral component is controlled to rotate to drive the second raw material to move downward, and at the same time, the air supply valve on the air supply pipe, the first-level air charging valve on the first-level air charging pipe, the second-level air charging valve on the second-level air charging pipe, and the third-level air charging valve on the third-level air charging pipe are opened. The gas from the first-level air charging valve flows into the spiral component and is ejected through the air hole to accelerate the downward movement of the second raw material, and then reaches the bottom of the intermediate feeding pipe, and enters the feeding conveying pipe under the action of the pressure difference between the crucible and the feeding tank, and the air supply from the third-level air charging valve further promotes the second raw material to enter the feeding conveying pipe, thereby reaching the crucible to feed the raw material bin in the crucible.

[0031] In some preferred embodiments of the present invention, the Si / C ratio in the first raw material is in the range of 0.8-0.95, and the Si / C ratio in the second raw material is in the range of 1.05-1.2, calculated in atomic percentage.

[0032] In some preferred embodiments of the present invention, the particle diameter of the first raw material is 5 mm-10 mm.

[0033] In some preferred embodiments of the present invention, the particle diameter of the second raw material is 4 mm-8 mm.

[0034] In some preferred embodiments of the present invention, the pressure in the crucible is lower than the pressure in the feeding tank, and the absolute value of the pressure difference between the two is 10-50 Pa.

[0035] In some preferred embodiments of the present invention, the silicon carbide growth method further comprises at least one of the following steps:

[0036] Step a: When adding material, the crucible support mechanism is controlled by the second rotation drive mechanism to drive the crucible to rotate;

[0037] Step b, during the crystal growth process, measuring the weight change of the growing crystal by a second weighing device to obtain the change in crystal thickness; and moving the seed crystal upward by a lifting drive mechanism according to the change in crystal thickness so that the distance between the crystal growth interface and the upper surface of the solid material in the raw material bin remains unchanged;

[0038] Step c: During the crystal growth process, the weight change of the growing crystal is measured by the second weighing device, and the target opening of the first ball valve is adjusted according to the weight change of the crystal to control the second raw material to reach the target feeding amount.

[0039] Beneficial effects:

[0040] The present invention utilizes the above-mentioned solution, particularly the provision of a specifically structured quantitative feeding device and its coordination with the crucible, and the specifically configured three-stage gas supply structure within the quantitative feeding device. This allows for stable feeding of materials at the bottom of the crucible and the addition of required raw materials during crystal growth, thereby increasing the thickness of the grown crystals and improving the internal quality of the crystals. In some preferred embodiments, a first raw material can be pre-loaded into the raw material bin, and a Si-rich silicon carbide raw material can be added as a second raw material via the quantitative feeding device, such that the Si / C ratio of the second raw material is within the range of 1.05-1.2, while the Si / C ratio in the growth atmosphere is maintained at approximately 1.0. This allows the growth of high-quality, low-defect silicon carbide crystals, as well as thicker crystals (over 100 mm thick), thereby avoiding the problem in prior art crystal growth where excess carbon is deposited on the crystal growth surface to form inclusions, resulting in a serious imbalance in the raw material component ratios, necessitating the termination of growth and resulting in a small thickness (conventional silicon carbide crystals are generally less than 30 mm thick).

[0041] Furthermore, the quantitative feeding device provided in the present invention enables crystal growth in crucibles with a small height, reducing crucible costs and solving the problem of crucible loading capacity. Furthermore, when growing crystals with a diameter of 6 inches or more, the top material outlet of the feeding and conveying pipe can be positioned at the corresponding height of the bottom of the crucible, saving space, simplifying the structure, and maintaining thermal field uniformity. This further contributes to thermal field temperature stability.

[0042] In the preferred silicon carbide growth method of the present invention, a first raw material with a Si / C ratio in the range of 0.8-0.95 is loaded into the raw material bin of the crucible, so that high-quality, low-defect silicon carbide crystals can be obtained in the early stage of growth; at the same time, a silicon-rich second raw material with a Si / C ratio in the range of 1.05-1.2 can be supplemented during the crystal growth process, so that the Si / C ratio in the gas phase is close to 1.0, ensuring the internal quality of the crystal in the middle and late stages of growth.

[0043] In a further preferred silicon carbide growth method, according to the weight change of the growing crystal, a silicon-rich second raw material can be added while the crystal moves upward, so that the temperature gradient and distance between the crystal growth interface and the material surface in the raw material bin remain relatively constant, the crystal growth interface is maintained stable, and silicon carbide crystals with uniform internal quality are obtained; and / or, according to the weight change of the growing crystal, the second raw material is controlled to reach a target feeding amount, so that during the entire crystal growth process, the Si / C atomic ratio in the gas phase in the crucible is close to 1.0, thereby further improving the growth quality of the silicon carbide crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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.

[0045] Figure 1 It is a structural schematic diagram of a specific embodiment of the silicon carbide growth furnace capable of quantitative feeding of the present invention;

[0046] Figure 2 It is a partial structural schematic diagram of a specific embodiment of the quantitative feeding device of the present invention;

[0047] Figure 3 It is a partial structural diagram of a specific embodiment of the cooperation between the crucible and the feeding and conveying pipe of the present invention.

[0048] Figure 4 It is a partial structural diagram of a specific implementation method of the cooperation between the air slip ring and the orifice plate, the feeding and conveying pipeline, and the intermediate feeding pipeline of the present invention.

[0049] Description of Reference Numerals

[0050] 100. Furnace body, 11. First vacuum gauge, 12. Vacuum outlet; 200. Crucible, 21. Seed crystal mounting portion, 22. Raw material bin, 23. Porous graphite, 24. First guide plate, 25. Second guide plate, 26. Third guide plate, 27. Spacer, 2701. Evaporation and feeding gap, 28. Lifting shaft, 29. Infrared pyrometer; 300. Quantitative feeding device, 31. Feeding tank, 3101. Gas supply pipe, 3102. Vacuum pipe, 3103. Gas supply valve, 3104. Vacuum valve, 3105. Second vacuum gauge; 32. Screw feeding device, 3201. Rotating shaft, 3202. Blades, 3203. First-stage charging pipe, 3204. First-stage charging valve, 3205. Rotating motor; 33. Feeding Conveying pipeline, 3301, three-stage inflation pipeline, 3302, three-stage inflation valve; 34, intermediate feeding pipeline, 3401, previous pipeline, 3402, next pipeline, 3403, two-stage inflation pipeline, 3404, two-stage inflation valve, 3405, feeding hole, 3407, orifice plate; 35, first ball valve, 36, second ball valve, 37, gas slip ring, 3701, fixing part, 3702, sealing ring, 3703, inert gas inlet, 38, first bellows, 39, sleeve; 400, first weighing device; 500, second weighing device; 600, crucible support mechanism; 700, crucible lifting mechanism, 71, second bellows; 800, second rotary drive mechanism; 900, insulation shell, 91, heater. DETAILED DESCRIPTION

[0051] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" generally refer to 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.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0053] 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.

[0054] 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.

[0055] 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 to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein. The terms "optional" and "optional" mean that a range may or may not be included (or may or may not be present).

[0056] In a first aspect, the present invention provides a silicon carbide growth furnace capable of quantitatively feeding materials, such as Figure 1As shown, it includes a furnace body 100 and a crucible 200. A seed crystal mounting portion 21 is provided on the top of the crucible 200. It also includes a quantitative feeding device 300 for continuously feeding materials into the crucible 200. A feeding pipe is provided at the bottom of the crucible 200. The feeding pipe extends from the bottom of the furnace body 100 and the bottom of the crucible 200 to the inside of the crucible 200 from bottom to top. A raw material bin 22 is formed between the feeding pipe and the inner wall of the crucible 200. The material in the raw material bin 22 and the material added by the quantitative feeding device 300 can be the same or different, and can be selected according to actual needs. It is understandable that the crucible 200 is arranged inside the furnace body 100.

[0057] like Figure 2 As shown, the quantitative feeding device 300 includes a feeding tank 31, a screw feeding device 32, and a feeding and conveying pipeline 33. The feeding tank 31 is provided with an air supply pipeline 3101 and a vacuum pipeline 3102. More preferably, an air supply valve 3103 is provided on the air supply pipeline 3101, and a vacuum valve 3104 is provided on the vacuum pipeline 3102, for jointly regulating the air pressure within the feeding tank 31. A first ball valve 35 with a controllable opening is provided at the outlet of the feeding tank 31 to control the amount of feeding.

[0058] like Figure 2 As shown, the spiral feeding device 32 includes a spiral member having a ventilation channel, which is connected to a plurality of air holes and distributed along the axial direction of the spiral member. The inlet of the ventilation channel is connected to a primary air charging pipe 3203. More preferably, a primary air charging valve 3204 is provided on the primary air charging pipe 3203. The primary air charging pipe 3203 is used to convey materials via a gas spiral. The spiral member of the present invention is disposed within the feeding tank 31 and extends along the central axis of the feeding tank 31 to provide spiral feeding.

[0059] In some preferred embodiments of the present invention, the spiral member extends to near the outlet of the feeding tank 31 .

[0060] In some preferred embodiments of the present invention, the spiral member includes a rotating shaft 3201 and blades 3202. The blades 3202 spirally surround the portion of the rotating shaft 3201 located within the feeding tank 31 and extend axially along the rotating shaft 3201. Further preferably, the rotating shaft 3201 is provided with the ventilation channel and the air holes; the top of the rotating shaft 3201 is connected to the outlet of the primary air pipe 3203, which can further accelerate the movement of materials.

[0061] In some preferred embodiments of the present invention, the screw feeding device 32 further includes a rotary motor for driving the screw to rotate. The rotary motor is connected to the top of the rotating shaft 3201 and is located outside the feeding tank 31 .

[0062] The upper portion of the feeding and conveying pipe 33 of the present invention is disposed within the feeding pipe and extends above the height of the raw material bin 22, communicating with the raw material bin 22 for feeding. Specifically, the upper portion of the feeding and conveying pipe 33 is inserted into the raw material bin 22 and positioned above the raw material bin 22. The feeding and conveying pipe 33 is used to convey material into the crucible 200. The portion of the sidewall of the feeding and conveying pipe 33 located outside the furnace body 100 is sealedly connected to the furnace body 100, and the lower portion of the feeding and conveying pipe 33 has a side inlet and a bottom inlet. The bottom inlet is connected to a three-stage gas charging pipe 3301 for introducing inert carrier gas. More preferably, the three-stage gas charging pipe 3301 is provided with a three-stage gas charging valve 3302. The three-stage gas charging pipe 3301 is used to facilitate the complete delivery of the feeding material into the crucible 200 by adding an inert carrier gas path, thereby preventing the material from falling or flowing back. The inert gas carrier gas will then flow out from the gap between the crucible cover where the seed crystal mounting portion 21 is located and the crucible body. Figure 3 The direction of the arrow near the seed crystal mounting portion 21 is shown. It can be understood that the crucible cover and the crucible body form the crucible 200.

[0063] The side inlet is connected to the outlet of the feeding tank 31 via an intermediate feeding pipe 34. The intermediate feeding pipe 34 can be configured according to actual site requirements, for example, by a single pipe, or by interconnecting multiple pipes, with the multiple pipes being sequentially divided into a front pipe 3401, a rear pipe 3402, etc., along the material conveying direction.

[0064] When the intermediate feed pipe 34 connects two or more pipes, the outlet of the preceding pipe 3401 is inserted into the inlet of the succeeding pipe 3402, creating a non-contact, sealed connection. A secondary inflation pipe 3403 is installed at this sealed connection. More preferably, a secondary inflation valve 3404 is provided on the secondary inflation pipe 3403. This prevents material from flowing back into the preceding pipe 3401. A non-contact, sealed connection means that the preceding pipe 3401 and the succeeding pipe 3402 are in indirect contact through other components, rather than direct contact.

[0065] In some preferred embodiments of the present invention, Figure 2As shown, the non-contact sealing sleeve structure includes a first bellows 38 and a sleeve 39. The sleeve 39 is sleeved on the outer surface of the outlet end of the preceding pipe 3401 and extends to the outer surface of the inlet end of the following pipe 3402. The first bellows 38 is sleeved outside the sleeve 39 with both ends extending outward. One end of the first bellows 38 is sleeved on the outer surface of the preceding pipe 3401 and the other end is sleeved on the outer surface of the following pipe 3402. The secondary inflation pipe 3403 is provided on the end surface of the first bellows 38 adjacent to the preceding pipe 3401. Preferably, the radial dimensions of the two end surfaces of the first bellows 38 and the sleeve 39 are different. The first bellows 38 can provide both vacuum sealing and shock absorption. When the secondary inflation valve 3404 is opened, the gas will flow into the rear pipe 3402 along the sleeve 39, preventing the raw material from flowing into the first bellows 38, thereby increasing the service life of the first bellows 38 and accelerating the fluidity of the material.

[0066] In some preferred embodiments of the present invention, Figure 2 As shown, a second ball valve 36 with controllable opening is provided near the outlet of the previous pipe 3401 . The second ball valve 36 is used to control the amount of material entering the feeding and conveying pipe 33 , thereby further improving the distribution uniformity of the material entering the crucible 200 .

[0067] In some preferred embodiments of the present invention, Figure 3As shown, the silicon carbide growth furnace capable of quantitative feeding also includes porous graphite 23, a first guide plate 24 and a third guide plate 26. The porous graphite 23 is located between the seed crystal mounting portion 21 and the raw material bin 22 and divides the two into an upper chamber and a lower chamber. The first guide plate 24 and the third guide plate 26 are both located in the lower chamber. The bottom of the first guide plate 24 is fixed on the feeding and conveying pipe 33 and a gap is left between its edge and the inner wall of the crucible 200. The outlet of the feeding and conveying pipe 33 is located below the first guide plate 24, and the radial dimension of the first guide plate 24 is larger than the radial dimension of the feeding and conveying pipe 33. One end of the third guide plate 26 is fixed on the inner wall of the crucible 200 and the other end is suspended close to the edge of the first guide plate 24. The suspended end of the third guide plate 26 is arranged close to the edge of the first guide plate 24 in a zigzag manner to form a zigzag logistics channel. Since the gas flowability in the crucible 200 is increased and the content of particles in the gas is increased when the material is conveyed by the quantitative feeding device 300, on the one hand, the first guide plate 24 and the third guide plate 26 are provided to form a tortuous logistics channel. As a maze structure, the gas flow path is extended, which is conducive to promoting the high-temperature gasification of the particles. The curved path will block the ungasified particles (dust) below the first guide plate 24, preventing the particles (dust) from drifting to the crystal growth interface. Larger particles of raw materials will fall into the raw material bin 22 of the crucible 200. Combined with the porous graphite 23, the high-temperature gasification of the particles can be further promoted, thereby further improving the quality of crystal growth and reducing the probability of the material being conveyed to the crucible 200 without timely reaction and being entrained to the crystal growth surface. On the other hand, the first guide plate 24 and the third guide plate 26 cooperate with the structure of the feeding and conveying pipe 33 to form a multi-stage diversion structure, which can more evenly drop the silicon carbide raw material from the quantitative feeding device 300 into the crucible 200, reduce local accumulation of raw materials in the crucible 200, and reduce the uneven heating of the raw materials by the crucible 200 temperature, thereby better ensuring the quality of crystal growth.

[0068] In some preferred embodiments of the present invention, the edge of the first guide plate 24 is U-shaped, and the suspended end of the third guide plate 26 extends vertically downward into the U-shaped portion of the first guide plate 24, forming a U-shaped, tortuous flow channel. During the upward movement of the material, it must pass through this U-shaped, tortuous flow channel, further extending the gas flow path and promoting high-temperature gasification of the particles.

[0069] In some preferred embodiments of the present invention, Figure 3As shown, the silicon carbide growth furnace capable of quantitative feeding also includes a second guide plate 25. The second guide plate 25 is sleeved onto the outer surface of the feeding and conveying pipe 33 and extends radially and circumferentially along the feeding and conveying pipe 33. The second guide plate 25 is located below the top outlet of the feeding and conveying pipe 33 and below the first guide plate 24. The lower end of the second guide plate 25 is lower than the upper end, and the lower end of the second guide plate 25 extends above at least a portion of the adjacent raw material bin 22. The specially structured second guide plate 25 can guide the added material passing through the quantitative feeding device 300 into the raw material bin 22, further reducing the probability of material being carried to the crystal growth surface without timely reaction after being conveyed into the crucible 200.

[0070] In some preferred embodiments of the present invention, the upper portion of the second guide plate 25 is umbrella-shaped and the lower end of the umbrella extends vertically to above the adjacent portion of the raw material bin 22 , which can better guide the material and allow the material to sink into the raw material bin 22 .

[0071] In some preferred embodiments of the present invention, Figure 3 As shown, the silicon carbide growth furnace capable of quantitative feeding also includes a spacer 27 arranged in the crucible 200, the spacer 27 surrounds the outer surface of the corresponding feeding and conveying pipe 33 and leaves an evaporation and feeding gap 2701 between the two. The raw material bin 22 is formed between the spacer 27 and the inner wall of the crucible 200, and the material of the spacer 27 is a porous material (such as porous graphite) so that the raw material in the raw material bin 22 evaporates and enters the evaporation and feeding gap 2701 through the spacer 27; and the top of the feeding and conveying pipe 33 is sealed and a feeding through hole 3405 is provided near the top. The feeding through holes 3405 are arranged along the radial circumferential direction of the feeding and conveying pipe 33, and the feeding through holes 3405 are located between the first guide plate 24 and the second guide plate 25. The evaporation and feeding gap 2701 extends to between the top of the spacer 27 and the second guide plate 25 and continues to extend to the raw material bin 22. The evaporation feeding gap 2701 formed between the spacer 27 and the feeding and conveying pipe 33 can increase the evaporation area of the silicon carbide raw material.

[0072] In some preferred embodiments of the present invention, the lower part of the feeding and conveying pipeline 33 is connected to the three-stage inflation pipeline 3301 and the intermediate feeding pipeline 34 through an air slip ring 37, so that the inert gas carrier gas is introduced into the bottom inlet of the feeding and conveying pipeline 33 through the three-stage inflation pipeline 3301, and the material is fed from the intermediate feeding pipeline 34 into the side inlet of the feeding and conveying pipeline 33; this is more conducive to the uniform departure of the raw materials from the storage tank and reduces the occurrence of blockage of the raw materials in the pipeline.

[0073] In some preferred embodiments of the present invention, the radial dimension of the lower portion of the feeding tank 31 gradually decreases from top to bottom.

[0074] In some preferred embodiments of the present invention, a orifice plate 3407 for blocking raw material particles is provided between the bottom inlet of the feeding and conveying pipe 33 and the tertiary inflation pipe 3301, which can prevent large particles of raw materials from entering the tertiary inflation pipe 3301 and allow gas to pass through the orifice plate 3407.

[0075] Further, such as Figure 4 As shown, the air slip ring 37 includes a fixing member 3701, a sealing ring 3702, and an inert gas inlet 3703. The fixing member 3701 has an accommodating cavity, and the inert gas inlet 3703 is arranged below the accommodating cavity. The inert gas inlet 3703 is connected to the accommodating cavity. The lower portion of the feeding and conveying pipeline 33 extends into the accommodating cavity, and the side wall thereof is sealed with the fixing member 3701 by the sealing ring 3702. The tertiary inflation pipeline 3301 extends into the inert gas inlet 3703 and is connected to the bottom inlet of the feeding and conveying pipeline 33 through the orifice plate 3407. The side inlet of the feeding and conveying pipeline 33 is connected to the rear pipeline 3402 of the intermediate feeding pipeline 34. During operation, the inert gas carrier gas enters the orifice plate 3407 and the bottom inlet of the feeding and conveying pipe 33 in sequence from the three-stage filling pipe 3301 through the inert gas inlet 3703, and the replenishment or addition of material enters the side inlet of the feeding and conveying pipe 33 through the rear pipe 3402 of the intermediate feeding pipe 34, and is transported toward the crucible under the action of the inert gas carrier gas.

[0076] In some preferred embodiments of the present invention, Figure 1 As shown, the silicon carbide growth furnace capable of quantitative feeding also includes a lifting shaft 28, a lifting drive mechanism, and a first rotary drive mechanism. One end of the lifting shaft 28 extends into the crucible 200 and is sealed and rotatably connected to the crucible 200 and fixedly mounted on the seed crystal mounting portion 21. The other end of the lifting shaft 28 extends outside the furnace body 100 and is connected to the lifting drive mechanism and the first rotary drive mechanism respectively. The lifting shaft 28 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 slowly move upward, keeping the growth interface of the crystal unchanged, so that the crystal growth continues, and further efficiently solves the problem of small crystal thickness due to insufficient raw materials. The first rotary drive mechanism is used to drive the lifting shaft 28 to rotate, so that the seed crystal and its crystal are controlled to rotate synchronously with the rotation of the crucible.

[0077] In some preferred embodiments of the present invention, Figure 1 and Figure 2As shown, the silicon carbide growth furnace capable of quantitative feeding further includes a first weighing device 400 for weighing the feeding tank 31 and a second weighing device 500 for weighing the seed crystal and the crystal grown therefrom. The first weighing device 400 is mounted on the feeding tank 31, and the second weighing device 500 is mounted on the portion of the lifting shaft 28 located outside the furnace body 100. The second weighing device 500 can weigh the seed crystal and the crystal grown therefrom, thereby obtaining a weight change of the crystal, and based on this, the crystal growth rate is obtained, thereby determining the required feeding amount of the quantitative feeding device 300. The first weighing device 400 can weigh the feeding tank 31 in real time to determine the feeding amount, thereby achieving precise control of the feeding amount.

[0078] The first weighing device 400 and the second weighing device 500 can be weighing devices in the prior art that can achieve the required functions.

[0079] In some preferred embodiments of the present invention, Figure 1 As shown, the silicon carbide growth furnace capable of quantitative feeding also includes a crucible support mechanism 600 and a crucible lifting mechanism 700. The crucible support mechanism 600 is mounted below the crucible 200 and is sleeved on the outer surface of the feeding and conveying pipe 33 via a bearing, extending outward along with the feeding and conveying pipe 33. The crucible lifting mechanism 700 is disposed outside the furnace body 100. The crucible lifting mechanism 700 is connected to the outwardly extending portion of the crucible support mechanism 600, and this connection is sealed with the furnace body 100 by a second bellows 71. The crucible lifting mechanism 700 is used to drive the crucible support mechanism 600 to move the crucible 200 upward and downward. The second bellows 71 not only provides a seal but also expands and contracts as the crucible 200 rises and falls. It is understood that the second bellows 71 is sleeved outside the crucible support mechanism 600 to achieve an overall seal.

[0080] In some preferred embodiments of the present invention, Figure 1 As shown, the silicon carbide growth furnace capable of quantitative feeding also includes a second rotary drive mechanism 800, which is disposed outside the furnace body 100. This second rotary drive mechanism 800 is connected to the outwardly extending portion of the crucible support mechanism 600 and is used to control the rotation of the crucible 200 to ensure uniform heating of the crucible 200. The feeding and delivery conduit 33 does not rotate, while the crucible 200 rotates. This ensures that the raw materials are evenly distributed within the crucible 200, ensuring uniform heating and facilitating volatilization of the raw materials.

[0081] In the present invention, when the crucible lifting mechanism 700 drives the crucible to rise and fall, the second rotary drive mechanism 800 and the crucible support mechanism 600 are lifted and lowered accordingly; when the second rotary drive mechanism 800 drives the crucible support mechanism 600 to rotate the crucible 200, the crucible lifting mechanism 700 remains stationary; based on this, those skilled in the art can refer to the prior art to set the connection structure between the crucible lifting mechanism 700, the second rotary drive mechanism 800 and the crucible support mechanism 600. For example, the specific connection structure of the second rotary drive mechanism 800 and the crucible lifting mechanism 700 can refer to the corresponding connection in the prior art, as long as it can achieve the required function, for example, the crucible lifting mechanism 700 can be connected to a worm gear reducer via a servo motor, the worm gear reducer is connected to a screw, the screw is connected to a slide, a linear slide is set on the slide for the crucible support mechanism 600 to slide, and the linear slide serves as a guide and weighing function, and the screw serves as a power source to drive the crucible support mechanism 600 and the second rotary drive mechanism 800 to move up and down. The second rotation driving mechanism 800 includes a rotation platform. The crucible supporting mechanism 600 is located on and connected to the rotation platform. The rotation platform is driven by a servo motor to realize the circumferential rotation of the crucible supporting mechanism 600 by the rotation platform.

[0082] Furthermore, in some specific embodiments, the silicon carbide growth furnace capable of quantitative feeding may also include a lifting platform that supports the feeding tank 31, allowing the feeding tank 31 to move synchronously with the crucible 200 driven by the crucible support mechanism 600, thereby facilitating the stability of the feeding system. To ensure stable lifting and lowering of the quantitative feeding device 300, the various pipes contained therein may be flexibly connected. Flexibility is a mature existing technology and will not be further described here.

[0083] In some preferred embodiments of the present invention, Figure 1 and Figure 2 As shown, a first vacuum gauge 11 is provided on the furnace body 100 , and a second vacuum gauge 3105 is provided on the feeding tank 31 for testing the vacuum degree of the furnace body 100 or the feeding tank 31 .

[0084] Furthermore, the silicon carbide growth furnace capable of quantitative feeding also includes a PLC controller, which is electrically connected to the first-stage inflation valve 3204, the third-stage inflation valve 3302, the second-stage inflation valve 3404, the first ball valve 35, the first vacuum gauge 11, the second vacuum gauge 3105, the gas supply valve 3103, and the optional second ball valve 36 and the spiral feeding device 32, so as to realize the control of related processes according to the required target parameters.

[0085] The silicon carbide growth furnace capable of quantitative feeding of the present invention may also include other conventional components. In some preferred embodiments of the present invention, Figure 1As shown, the silicon carbide growth furnace capable of quantitative feeding also includes an insulating shell 900, a heater 91, and an infrared pyrometer 29 for detecting the temperature of the seed crystal. The infrared pyrometer 29 is located outside the furnace body 100 and directly above the seed crystal to detect the temperature on the side opposite the seed crystal mounting portion 21. The insulating shell 900 is located outside the crucible 200 and the feeding pipe and inside the furnace body 100. The heater 91 is located between the insulating shell 900 and the crucible 200. A vacuum port 12 is provided on the side of the furnace body 100. The seed crystal mounting portion 21 can be, for example, a crystal growth tray.

[0086] In a second aspect, the present invention provides a silicon carbide growth method, which is carried out in the silicon carbide growth furnace capable of quantitative feeding as described in the first aspect.

[0087] The silicon carbide growth method includes: loading a first raw material into the raw material bin 22 of the crucible 200 in advance, and loading a second raw material into the feeding tank 31; wherein the carbon atom content in the first raw material is greater than the silicon atom content, and the carbon atom content in the second raw material is less than the silicon atom content; and then heating the crucible 200 to grow silicon carbide crystals.

[0088] The silicon carbide growth method further includes: in the middle and / or late stages of crystal growth, feeding the material through the quantitative feeding device 300, specifically, first adjusting the vacuum degree in the feeding tank 31 through the vacuum valve 3104 on the vacuum pipe 3102 in the quantitative feeding device 300 to make it the same as the vacuum degree of the working chamber where the crucible 200 is located; then opening the first ball valve 35 to make it at a target opening, controlling the spiral member to rotate and drive the second raw material to move downward, and at the same time opening the gas supply valve 3103, the first-stage gas charging valve 3204, and the second-stage gas charging valve 3205; The gas from the inflation valve 3404, the third-level inflation valve 3302, and the first-level inflation valve 3204 flows into the spiral element and is ejected through the air hole to accelerate the downward movement of the second raw material, and then reaches the bottom of the intermediate feeding pipe 34. Under the action of the pressure difference between the crucible 200 and the feeding tank 31, it enters the feeding and conveying pipe 33, and the gas supply from the third-level inflation valve 3302 further promotes the second raw material to enter the feeding and conveying pipe 33, thereby reaching the crucible 200 and replenishing the raw material bin 22 in the crucible 200.

[0089] In some preferred embodiments of the present invention, the Si / C ratio in the first raw material is in the range of 0.8-0.95, and the Si / C ratio in the second raw material is in the range of 1.05-1.2, calculated in terms of atomic percentage. By using the first raw material and the second raw material with appropriate compositions, the Si / C atomic ratio in the gas phase in the crucible 200 can be closer to 1.0 during the entire crystal growth process, which is more conducive to improving the quality of the silicon carbide crystal.

[0090] In some preferred embodiments of the present invention, the particle diameter of the first raw material is 5 mm-10 mm.

[0091] In some preferred embodiments of the present invention, the particle diameter of the second raw material is between 4 mm and 8 mm. This preferred range of particle diameters for the silicon-rich second raw material effectively prevents the formation of dust within crucible 200, which could potentially drift onto the crystal growth surface before sublimation and form inclusion defects. Furthermore, it facilitates pipeline transportation.

[0092] In some preferred embodiments of the present invention, the pressure in the crucible 200 is lower than the pressure in the feeding tank 31 and the absolute value of the pressure difference between the two is 10-50 Pa, which is more conducive to promoting the maximum amount of material to enter the crucible 200 and avoiding material backflow.

[0093] In some preferred embodiments of the present invention, the silicon carbide growth method further comprises step a: during feeding, the crucible support mechanism 600 is controlled by the second rotary drive mechanism 800 to rotate the crucible 200. This facilitates uniform distribution of the added material and accelerates the heating of the silicon carbide raw material, thereby accelerating solid-gas conversion.

[0094] In some preferred embodiments of the present invention, the silicon carbide growth method also includes step b, during the crystal growth process, measuring the weight change of the growing crystal by a second weighing device 500, thereby obtaining the change in crystal thickness; according to the change in crystal thickness, the seed crystal is moved upward by a lifting drive mechanism, so that the distance between the crystal growth interface and the upper surface of the solid material in the raw material bin 22 remains unchanged, which is more conducive to maintaining the stability of the crystal growth interface and obtaining a silicon carbide crystal with no internal quality defects.

[0095] In some preferred embodiments of the present invention, the silicon carbide growth method further includes step c, during the crystal growth process, measuring the weight change of the growing crystal by a second weighing device 500, adjusting the target opening of the first ball valve 35 according to the weight change of the crystal, and controlling the second raw material to reach the target feeding amount. This preferred solution ensures that the Si / C atomic ratio in the gas phase in the crucible 200 is close to 1.0 (for example, it can be 1.0±0.2, preferably 1.0±0.1) during the entire crystal growth process, thereby further improving the growth quality of the silicon carbide crystal.

[0096] In some specific embodiments of the present invention, a method for growing silicon carbide, in Figure 1 、 Figure 2 and Figure 3 The silicon carbide growth furnace shown is carried out, including:

[0097] A first raw material with a Si / C atomic ratio in the range of 0.8-0.95 is loaded into the raw material bin 22 of the crucible 200 , and a second raw material with a Si / C atomic ratio in the range of 1.05-1.2 is loaded into the feeding tank 31 . Based on the test values of the first vacuum gauge 11 and the second vacuum gauge 3105, the PLC controller compares the vacuum level of the working chamber in the furnace body 100 where the crucible 200 is located with the vacuum level in the feeding tank 31. When the vacuum levels are equal, the vacuum valve 3104 on the feeding tank 31 is closed, and the first-stage air charging valve 3204 and the air supply valve 3103 are opened in sequence to the required openings. The rotary motor is started, which drives the rotating shaft 3201 in the spiral element, which drives the second raw material downward. At the same time, the first-stage air charging valve 3204, the air supply valve 3103, and the second-stage air charging valve 3404 are opened. The gas from the first-stage air charging valve 3204 flows through the air slip ring 37 into the ventilation channel in the spiral feeding device 32, and is then blown into the feeding tank 31 through the air holes connected to the ventilation channel, thereby accelerating the downward flow of the second raw material. The front pipe 3401 and the rear pipe 3402 in the intermediate feeding pipe 34 are connected in a non-contact sealed manner through the first bellows 38. The first bellows 38 plays a shock-absorbing and vacuum-sealing role. In order to prevent the second raw material from flowing onto the first bellows 38, a sleeve 39 is added to the front pipe 3401, and a secondary inflation pipe 3403 is added in the axial direction of the first bellows 38 near the front pipe 3401. When the secondary inflation valve 3404 on it is opened, the gas will flow into the rear pipe 3402 along the sleeve 39, thereby preventing the raw material from flowing into the first bellows 38, increasing the service life of the first bellows 38, and accelerating the fluidity of the second raw material. When the second raw material reaches the bottom of the feeding and conveying pipe 33, a portion of the second raw material flows into the crucible 200 due to the pressure difference between the feeding tank 31 and the crucible 200. Some large particles fall onto the orifice plate 3407. At this point, the three-stage gas filling valve 3302 below is opened, and inert gas flows from the three-stage gas filling pipe 3301 along the pipeline to the bottom of the orifice plate 3407, lifting the larger particles and transporting them into the feeding and conveying pipe 33. To prevent microparticles from adhering to the crystal without sublimation after reaching the crucible 200, a first guide plate 24, a third guide plate 26, and porous graphite 23 are added to the crucible 200. The first and third guide plates 24, 26 form a labyrinthine structure, which blocks fine particles (dust) below the first guide plate 24, preventing them from drifting onto the crystal growth surface. Larger particles of raw material fall into the crucible 200.

[0098] During feeding, the feed delivery conduit 33 remains stationary. The crucible 200 is rotated by the crucible support mechanism 600 driven by the second rotary drive mechanism 800. The feed delivery conduit 33 and the crucible support mechanism 600 are connected by a bearing. As the crucible 200 slowly rotates, the second raw material is evenly distributed within the raw material bin 22 at the bottom of the crucible 200 along the second guide plate 25. As the crystal thickens, it slowly moves upward, maintaining a constant growth interface and enabling continued crystal growth. This solves the problem of low crystal thickness due to insufficient raw material.

[0099] Furthermore, the present invention can also configure the silicon carbide seed crystal with lifting, rotation and weighing functions through the lifting shaft 28, the lifting drive mechanism, the first rotation drive mechanism, and the second weighing device 500. During the crystal growth process, the change in crystal thickness is calculated by the change in the weight of the crystal, and the silicon carbide seed crystal is moved upward by the lifting drive mechanism; the second raw material is added according to the change in the crystal weight, and the feeding speed is controlled by the PLC controller so that the distance between the crystal growth interface and the upper surface of the material in the raw material bin 22 remains unchanged, and the temperature difference between the crystal growth interface and the upper surface of the material in the raw material bin 22 remains relatively stable. During the entire crystal growth process, the Si / C ratio in the gas phase is close to 1.0, the crystal can always maintain a stable growth state, and it is easier to obtain silicon carbide crystals with high thickness and good quality.

[0100] The present invention can realize the growth of silicon carbide crystals with a thickness of more than 100 mm.

[0101] Prior art silicon carbide growth furnaces cannot be fed with raw materials. Instead, ordinary raw materials with a Si:C atomic ratio of 1:1 are added to the crucible 200 and then crystal growth proceeds directly. The resulting silicon carbide crystals are generally less than 30 mm thick. However, the present invention's specifically designed silicon carbide growth furnace capable of quantitative feeding and its silicon carbide growth method utilize the complementary use of first and second raw materials, as well as quantitative feeding during the middle and / or late stages of crystal growth. The resulting silicon carbide crystals can be over 100 mm thick, significantly exceeding the thickness and quality of silicon carbide crystals obtained in prior art silicon carbide growth furnaces.

[0102] 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 growth furnace capable of quantitative feeding, comprising a furnace body and a crucible, wherein a seed crystal mounting portion is provided on the top of the crucible, characterized in that: It also includes a quantitative feeding device, which includes a feeding tank, a spiral feeding device, and a feeding and conveying pipeline; wherein the feeding tank is provided with an air supply pipeline and a vacuum pipeline; The spiral feeding device includes a spiral member, the spiral member has a ventilation channel, and 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 member; the inlet of the ventilation channel is connected to a primary inflation pipe; A feeding pipe is provided at the lower part of the crucible, and the feeding pipe extends from the bottom of the furnace body and the bottom of the crucible to the inside of the crucible from bottom to top, and a raw material bin is formed between the feeding pipe and the inner wall of the crucible; the upper part of the feeding and conveying pipe is arranged in the feeding pipe and extends to above the height of the raw material bin and is connected to the raw material bin for feeding; the side wall of the feeding and conveying pipe located outside the furnace body is sealedly connected to the furnace body, and the lower part of the feeding and conveying pipe has a side inlet and a bottom inlet; the bottom inlet is connected to a three-stage inflation pipe to introduce inert gas carrier gas; a perforated plate for blocking raw material particles is provided between the bottom inlet of the feeding and conveying pipe and the three-stage inflation pipe; The side inlet is connected to the outlet of the feeding tank through an intermediate feeding pipe, and a first ball valve with controllable opening is provided at the outlet of the feeding tank; and when the intermediate feeding pipe is used to connect two or more pipes, the outlet end of the previous pipe is extended into the inlet end of the next pipe and a non-contact sealing connection is performed, and a secondary inflation pipe is provided at the sealing connection.

2. The silicon carbide growth furnace capable of quantitative feeding according to claim 1, characterized in that: The silicon carbide growth furnace capable of quantitative feeding also includes porous graphite, a first guide plate and a third guide plate. The porous graphite is located between the seed crystal mounting portion and the raw material bin and separates the two into an upper chamber and a lower chamber. The first guide plate and the third guide plate are both located in the lower chamber. The bottom of the first guide plate is fixed on the feeding and conveying pipe and a gap is left between its edge and the inner wall of the crucible. The outlet of the feeding and conveying pipe is located below the first guide plate, and the radial dimension of the first guide plate is larger than the radial dimension of the feeding and conveying pipe. One end of the third guide plate is fixed on the inner wall of the crucible and the other end is suspended close to the edge of the first guide plate. The suspended end of the third guide plate is zigzag close to the edge of the first guide plate to form a zigzag logistics channel.

3. The silicon carbide growth furnace capable of quantitative feeding according to claim 2, characterized in that: The edge portion of the first guide plate is U-shaped, and the suspended end portion of the third guide plate vertically extends downward to the U-shaped portion of the first guide plate, forming a U-shaped tortuous logistics channel.

4. The silicon carbide growth furnace capable of quantitative feeding according to claim 2, characterized in that: The silicon carbide growth furnace capable of quantitative feeding also includes a second guide plate, which is sleeved on the outer surface of the feeding and conveying pipe and extends along the radial circumferential direction of the feeding and conveying pipe. The second guide plate is located below the top outlet of the feeding and conveying pipe and below the first guide plate. The lower end height of the second guide plate is lower than the upper end height of the second guide plate, and the lower end of the second guide plate extends at least to the top of an adjacent portion of the raw material bin.

5. The silicon carbide growth furnace capable of quantitative feeding according to claim 4, characterized in that: The silicon carbide growth furnace capable of quantitative feeding also includes a spacer sleeve arranged in the crucible, the spacer sleeve surrounds the outer surface of the corresponding feeding and conveying pipe and an evaporation and feeding gap is left between the two, the raw material bin is formed between the spacer sleeve and the inner wall of the crucible, and the material of the spacer sleeve is porous material, so that the raw material in the raw material bin can enter the evaporation and feeding gap through the spacer sleeve after evaporation; and the top of the feeding and conveying pipe is sealed and a feeding through hole is provided near the top, and the feeding through holes are arranged along the radial circumferential direction of the feeding and conveying pipe, and the feeding through holes are located between the first guide plate and the second guide plate, and the evaporation and feeding gap extends between the top of the spacer sleeve and the second guide plate and continues to extend to the raw material bin.

6. The silicon carbide growth furnace capable of quantitative feeding according to claim 4, characterized in that: The upper portion of the second guide plate is umbrella-shaped, and the lower end of the umbrella extends vertically to above an adjacent portion of the raw material bin.

7. The silicon carbide growth furnace capable of quantitative feeding according to claim 1, characterized in that: The lower portion of the feeding and conveying pipeline is connected to the three-stage gas charging pipeline and the intermediate feeding pipeline through a gas slip ring, so that the inert gas carrier gas is introduced into the bottom inlet of the feeding and conveying pipeline through the three-stage gas charging pipeline, and the material is fed from the intermediate feeding pipeline into the side inlet of the feeding and conveying pipeline; And / or, the radial dimension of the lower portion of the feeding tank gradually decreases from top to bottom.

8. The silicon carbide growth furnace capable of quantitative feeding according to claim 1, characterized in that: The spiral extends to an outlet near the feeding tank; the spiral includes a rotating shaft and blades, the blades are spirally wrapped around the part of the rotating shaft located in the feeding tank 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 first-level inflation pipe; the spiral feeding device also includes a rotating motor for driving the spiral to rotate, the rotating motor is connected to the top of the rotating shaft and is located outside the feeding tank.

9. The silicon carbide growth furnace capable of quantitative feeding according to claim 1, characterized in that: A second ball valve capable of controlling the opening is provided near the outlet of the first pipeline, and / or The structure of the non-contact sealing sleeve includes a first bellows and a sleeve, the sleeve is sleeved on the outer surface of the outlet end of the previous pipe and extends to the outer surface of the inlet end of the subsequent pipe, the first bellows is sleeved outside the sleeve and both ends extend outward respectively, and one end of the first bellows is sleeved on the outer surface of the previous pipe and the other end is sleeved on the outer surface of the subsequent pipe, and the secondary inflation pipe is arranged on the end surface of the first bellows close to the previous pipe.

10. The silicon carbide growth furnace capable of quantitative feeding according to any one of claims 1 to 9, characterized in that: The silicon carbide growth furnace capable of quantitative feeding also includes a lifting shaft, a lifting drive mechanism, a first rotary drive mechanism, a first weighing device for weighing a feeding tank, and a second weighing device for weighing a seed crystal and a crystal grown therefrom, one end of the lifting shaft extending into the crucible and being sealed and rotatably connected to the crucible and fixedly mounted on the seed crystal mounting portion, the other end of the lifting shaft extending outside the furnace body and being respectively connected to the lifting drive mechanism and the first rotary drive mechanism, the first weighing device being mounted on the feeding tank, and the second weighing device being mounted on a portion of the lifting shaft located outside the furnace body; and / or, The silicon carbide growth furnace capable of quantitative feeding also includes a crucible supporting mechanism, a crucible lifting mechanism and a second rotary drive mechanism; wherein, the crucible supporting mechanism is installed below the crucible and is arranged on the outer surface of the feeding and conveying pipe through a bearing sleeve, and extends outward along with the feeding and conveying pipe; the crucible lifting mechanism and the second rotary drive mechanism are respectively arranged on the outside of the furnace body, the crucible lifting mechanism is connected to the outwardly extending part of the crucible supporting mechanism, and the connection between the crucible and the furnace body is sealed by a second bellows, which is used to drive the crucible supporting mechanism to drive the crucible to rise and fall; the second rotary drive mechanism is connected to the outwardly extending part of the crucible supporting mechanism, and is used to control the crucible to rotate.

11. The silicon carbide growth furnace capable of quantitative feeding according to any one of claims 1 to 9, characterized in that: A first vacuum gauge is provided on the furnace body, and a second vacuum gauge is also provided on the feeding tank; a gas supply valve is provided on the gas supply pipe, a vacuum valve is provided on the vacuum pipe, a first-level gas charging pipe is provided with a first-level gas charging valve, a third-level gas charging pipe is provided with a third-level gas charging valve, and a second-level gas charging pipe is provided with a second-level gas charging valve; and the silicon carbide growth furnace capable of quantitative feeding further includes a PLC controller, which is electrically connected to the first-level gas charging valve, the third-level gas charging valve, the second-level gas charging valve, the first ball valve, the first vacuum gauge, the second vacuum gauge, and the gas supply valve respectively; and / or, The silicon carbide growth furnace capable of quantitative feeding also includes an insulating shell, a heater, and an infrared pyrometer for detecting the temperature of the side of the seed crystal installed on the opposite side of the seed crystal mounting portion. The infrared pyrometer is located outside the furnace body and directly above the seed crystal. The insulating shell is located outside the crucible and the feeding pipe and inside the furnace body. The heater is located between the insulating shell and the crucible; and a vacuum outlet is provided on the side of the furnace body.

12. A method for growing silicon carbide, characterized in that: The method is carried out in a silicon carbide growth furnace capable of quantitative feeding as claimed in any one of claims 1 to 11, and the method comprises: loading a first raw material into a raw material bin of a crucible and loading a second raw material into a feeding tank; wherein the carbon atom content of the first raw material is greater than the silicon atom content, and the carbon atom content of the second raw material is less than the silicon atom content; and then heating the crucible to grow silicon carbide crystals; Among them, in the middle and / or late stages of crystal growth, feeding is carried out through a quantitative feeding device. Specifically, the vacuum degree in the feeding tank is first adjusted through the vacuum valve on the vacuum pipe to make it the same as the vacuum degree of the working chamber where the crucible is located; then the first ball valve is opened to make it at the target opening, and the spiral component is controlled to rotate to drive the second raw material to move downward, and at the same time, the air supply valve on the air supply pipe, the first-level air charging valve on the first-level air charging pipe, the second-level air charging valve on the second-level air charging pipe, and the third-level air charging valve on the third-level air charging pipe are opened. The gas from the first-level air charging valve flows into the spiral component and is ejected through the air hole to accelerate the downward movement of the second raw material, and then reaches the bottom of the intermediate feeding pipe, and enters the feeding conveying pipe under the action of the pressure difference between the crucible and the feeding tank, and the air supply from the third-level air charging valve further promotes the second raw material to enter the feeding conveying pipe, thereby reaching the crucible to feed the raw material bin in the crucible.

13. The silicon carbide growth method according to claim 12, wherein: In terms of atomic percentage, the Si / C ratio of the first raw material is in the range of 0.8-0.95, and the Si / C ratio of the second raw material is in the range of 1.05-1.2; the particle diameter of the first raw material is in the range of 5 mm-10 mm, and the particle diameter of the second raw material is in the range of 4 mm-8 mm; and / or, The pressure in the crucible is lower than the pressure in the feeding tank, and the absolute value of the pressure difference between the two is 10-50 Pa.

14. The silicon carbide growth method according to claim 12 or 13, characterized in that: The silicon carbide growth method further comprises at least one of the following steps: Step a: When adding material, the crucible support mechanism is controlled by the second rotation drive mechanism to drive the crucible to rotate; Step b, during the crystal growth process, measuring the weight change of the growing crystal by a second weighing device to obtain the change in crystal thickness; and moving the seed crystal upward by a lifting drive mechanism according to the change in crystal thickness so that the distance between the crystal growth interface and the upper surface of the solid material in the raw material bin remains unchanged; Step c: During the crystal growth process, the weight change of the growing crystal is measured by the second weighing device, and the target opening of the first ball valve is adjusted according to the weight change of the crystal to control the second raw material to reach the target feeding amount.

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