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

Abstract

The invention belongs to the technical field of silicon carbide crystal growth, and particularly relates to a silicon carbide growing furnace capable of achieving quantitative feeding and a silicon carbide growing method.The silicon carbide growing furnace comprises a furnace body and a crucible, a seed crystal mounting part is arranged at the top of the crucible, the silicon carbide growing furnace further comprises a quantitative feeding device, and the quantitative feeding device comprises a feeding tank, a spiral feeding device and a feeding conveying pipeline; a material supplementing pipeline is arranged at the lower part of the crucible and sequentially extends into the crucible from the bottom of the furnace body and the bottom of the crucible from bottom to top, and a raw material bin is formed between the material supplementing pipeline and the inner wall of the crucible; the upper portion of the feeding conveying pipeline is arranged in the material supplementing pipeline, extends to the position above the height where the raw material bin is located and communicates with the raw material bin for material supplementing. Continuous feeding can be achieved in the crystal growth process, the crystal growth thickness can be increased, and the internal quality of crystals can be improved.

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 quantitative feeding and a silicon carbide growth method. 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 material in a relatively closed crucible, sublimate carbon powder and silicon powder at a high temperature of more than 2000℃ and decompose them into Si atoms, Si 2 C molecules and SiC 2 Driven by the temperature gradient, these gas phase substances will be transported to the seed crystal with lower temperature to form silicon carbide crystal. By controlling the temperature field and other process parameters of PVT, a specific 4H-SiC crystal type can be grown.

[0003] Since the volume of the raw material in the crucible is fixed, the thickness of the grown SiC crystal is limited. After the crystal growth is completed, the crucible, silicon carbide crystal, heater, etc. need to be taken out and the graphite parts need to be cleaned, which is time-consuming and labor-intensive, affecting 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 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, and Si in the silicon carbide raw materials will evaporate preferentially at high temperatures. In the early stage of silicon carbide crystal growth, Si>C in the growth atmosphere, and 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 richer and richer in C atoms, making the Si / C atomic ratio in the gas phase in the late stage of crystal growth lower and lower, and the excess C will be deposited on the crystal growth surface to form inclusions. Since the crucible volume is fixed in the prior art, the growth must be terminated when the raw material component ratio is seriously unbalanced, so 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 which the thickness of silicon carbide crystals is small and has limitations when growing silicon carbide crystals by the PVT method, and to provide a silicon carbide growth furnace and a silicon carbide growth method that can add materials quantitatively, which can continuously add materials 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] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a silicon carbide growth furnace capable of quantitative feeding, comprising a furnace body and a crucible, a seed crystal mounting portion is arranged on the top of the crucible, and also comprises a quantitative feeding device, 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 arranged on the feeding tank; The spiral feeding device comprises a spiral member, the spiral member has a ventilation channel, and 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 member; the inlet of the ventilation channel is connected with a primary air charging pipeline; A feeding pipeline is provided at the lower part of the crucible, and the feeding pipeline 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 pipeline and the inner wall of the crucible; the upper part of the feeding and conveying pipeline is arranged in the feeding pipeline and extends to above the height of the raw material bin and is connected with the raw material bin for feeding; the side wall of the feeding and conveying pipeline located outside the furnace body is sealedly connected with the furnace body, and the lower part of the feeding and conveying pipeline has a side inlet and a bottom inlet; the bottom inlet is connected with a three-stage gas charging pipeline to introduce an inert gas carrier gas; The side inlet is connected to the outlet of the feeding tank through an intermediate feeding pipe, and a first ball valve capable of controlling the opening is arranged 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 subsequent pipe and a non-contact sealing sleeve is performed, and a secondary inflation pipe is arranged at the sealing sleeve.

[0008] 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, and 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.

[0009] 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 vertically extends downward to the U-shaped portion of the first guide plate to form a U-shaped tortuous logistics channel.

[0010] 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.

[0011] 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 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 arranged 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.

[0012] 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-shaped plate vertically extends to above an adjacent portion of the raw material bin.

[0013] 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.

[0014] 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.

[0015] In some preferred embodiments of the present invention, a perforated plate for blocking raw material particles is provided between the bottom inlet of the feed conveying pipeline and the tertiary aeration pipeline.

[0016] In some preferred embodiments of the present invention, the spiral element extends to near the outlet of the feeding tank.

[0017] In some preferred embodiments of the present invention, the screw 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 arranged on the rotating shaft; the top of the rotating shaft is connected to the outlet of the primary inflation pipe; the screw feeding device also includes a rotating motor for driving the screw member to rotate, the rotating motor is connected to the top of the rotating shaft and is located outside the feeding tank.

[0018] 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.

[0019] In some preferred embodiments of the present invention, the non-contact sealing sleeve structure 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 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.

[0020] In some preferred embodiments of the present invention, 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 thereon, 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, which 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.

[0021] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes a crucible supporting mechanism, a crucible lifting mechanism and a second rotary driving 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 with the feeding and conveying pipe; the crucible lifting mechanism and the second rotary driving 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 is sealed with the furnace body by a second bellows, which is used to drive the crucible supporting mechanism to drive the crucible to lift and lower; the second rotary driving mechanism is connected to the outwardly extending part of the crucible supporting mechanism, which is used to control the crucible to rotate.

[0022] In some preferred embodiments of the present invention, a first vacuum gauge is arranged on the furnace body, and a second vacuum gauge is also arranged on the feeding tank; a gas supply valve is arranged on the gas supply pipeline, a vacuum valve is arranged on the vacuum pipeline, a first-level inflation pipeline is provided with a first-level inflation valve, a third-level inflation pipeline is provided with a third-level inflation valve, and a second-level inflation pipeline is provided with a second-level inflation valve; and the silicon carbide growth furnace capable of quantitative feeding also includes a PLC controller, which is electrically connected to the first-level inflation valve, the third-level inflation valve, the second-level inflation valve, the first ball valve, the first vacuum gauge, the second vacuum gauge, and the gas supply valve, respectively.

[0023] In some preferred embodiments of the present invention, the silicon carbide growth furnace capable of quantitative feeding also includes an insulation shell, a heater, and an infrared pyrometer for detecting the temperature of a side of a seed crystal installed on the opposite side of a seed crystal mounting portion, the infrared pyrometer is located outside the furnace body and directly above the seed crystal, the insulation shell is located outside the crucible and the feeding pipeline and inside the furnace body, the heater is located between the insulation shell and the crucible; and a vacuum outlet is provided on the side of the furnace body.

[0024] In a second aspect, the present invention provides a method for growing silicon carbide, which is carried out in the silicon carbide growth furnace capable of quantitative feeding as described in the first aspect.

[0025] And the silicon carbide growth method comprises: The first raw material is loaded into the raw material bin of the crucible in advance, and the second raw material is loaded into the feeding tank; 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; then the crucible is heated to grow silicon carbide crystals.

[0026] 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 pipeline, the first-level air charging valve on the first-level air charging pipeline, the second-level air charging valve on the second-level air charging pipeline, and the third-level air charging valve on the third-level air charging pipeline 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 pipeline, and enters the feeding conveying pipeline 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 pipeline, thereby reaching the crucible, and the raw material bin in the crucible is fed with feed.

[0027] In some preferred embodiments of the present invention, in terms of atomic percentage, the Si / C in the first raw material is in the range of 0.8-0.95, and the Si / C in the second raw material is in the range of 1.05-1.2.

[0028] In some preferred embodiments of the present invention, the particle diameter of the first raw material is 5 mm-10 mm.

[0029] In some preferred embodiments of the present invention, the particle diameter of the second raw material is 4 mm-8 mm.

[0030] 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 10-50Pa.

[0031] In some preferred embodiments of the present invention, the silicon carbide growth method further comprises at least one of the following steps: Step a, when replenishing materials, controlling the crucible support mechanism through the second rotation drive mechanism to drive the crucible to rotate; Step b, during the crystal growth process, the weight change of the growing crystal is measured by a second weighing device to obtain 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 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 feed amount.

[0032] Beneficial effects: The present invention adopts the above scheme, especially sets a specific structure of quantitative feeding device and cooperates with the crucible, and the quantitative feeding device is specially provided with a three-stage gas supply structure, which can realize stable feeding at the bottom of the crucible, and can add the required raw materials during the crystal growth process, which can not only increase the thickness of the crystal growth, but also improve the internal quality of the crystal. In some preferred embodiments, the first raw material can be pre-loaded in the raw material bin, and the Si-rich silicon carbide raw material is added as the second raw material through the quantitative feeding device, so that the Si / C of the second raw material is within the range of 1.05-1.2, but the Si / C in the growth atmosphere is always maintained at about 1.0, not only can high-quality, low-defect silicon carbide crystals be grown, but also thicker (thickness of more than 100mm) crystals can be grown, avoiding the problem that the excess C in the crystal growth of the prior art will be deposited on the crystal growth surface to form inclusions, resulting in a serious imbalance in the raw material component ratio and the need to terminate the growth, resulting in a small thickness (the thickness of the traditional silicon carbide crystal is basically below 30mm).

[0033] Moreover, the quantitative feeding device provided in the present invention can make the crucible with a small height grow crystals, which not only reduces the cost of the crucible, but also solves the problem of the amount of material in the crucible; and when growing crystals with a diameter of more than 6 inches, the material outlet at the top of the feeding and conveying pipeline can be set at the corresponding height of the bottom of the crucible, which saves space, has a simple structure, does not destroy the uniformity of the thermal field, and is more conducive to the stability of the thermal field temperature.

[0034] 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.

[0035] 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 supplemented 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, thereby maintaining the crystal growth interface stable and obtaining silicon carbide crystals with uniform internal quality; and / or, according to the weight change of the growing crystal, the second raw material is controlled to reach a target replenishment 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

[0036] 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.

[0037] 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; Figure 2 It is a partial structural schematic diagram of a specific embodiment of the quantitative feeding device of the present invention; Figure 3 It is a partial structural schematic diagram of a specific implementation mode of the crucible and the feeding and conveying pipeline of the present invention.

[0038] Figure 4 It is a partial structural schematic 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.

[0039] Description of Reference Numerals 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 feeding gap, 28, lifting shaft, 29, infrared pyrometer; 300, quantitative feeding device, 31, feeding tank, 3101, air supply pipeline, 3102, vacuum pipeline, 3103, air supply valve, 3104, vacuum valve, 3105, second vacuum gauge; 32, spiral feeding device, 3201, rotating shaft, 3202, blade, 3203, primary charging pipeline, 3204, primary 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, secondary inflation pipeline, 3404, secondary 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 supporting mechanism; 700, crucible lifting mechanism, 71, second bellows; 800, second rotary drive mechanism; 900, insulation shell, 91, heater. DETAILED DESCRIPTION

[0040] In the present invention, 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.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] 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.

[0043] 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.

[0044] The endpoints and any values ​​of the ranges 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 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. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0045] In a first aspect, the present invention provides a silicon carbide growth furnace capable of quantitative feeding, such as Figure 1As shown, it includes a furnace body 100 and a crucible 200, a seed crystal mounting portion 21 is arranged on the top of the crucible 200, and a quantitative feeding device 300 is also included for continuously feeding into the crucible 200. A feeding pipeline is provided at the lower part of the crucible 200, and the feeding pipeline 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, and a raw material bin 22 is formed between the feeding pipeline and the inner wall of the crucible 200. Among them, 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 can be understood that the crucible 200 is arranged in the furnace body 100.

[0046] 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. Among them, 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, which are used to jointly regulate the air pressure in 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.

[0047] like Figure 2 As shown, the spiral feeding device 32 includes a spiral member, the spiral member has a ventilation channel, and 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 member; the inlet of the ventilation channel is connected with 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 by gas spiral. The spiral member of the present invention is arranged in the feeding tank 31 and extends along the central axis of the feeding tank 31 to feed the material by spiral.

[0048] In some preferred embodiments of the present invention, the spiral member extends to near the outlet of the feeding tank 31 .

[0049] In some preferred embodiments of the present invention, the spiral member includes a rotating shaft 3201 and blades 3202, wherein the blades 3202 spirally surround the portion of the rotating shaft 3201 located in the feeding tank 31 and extend along the axial direction of the rotating shaft 3201. Further preferably, the rotating shaft 3201 is provided with the ventilation channel and the air hole; the top of the rotating shaft 3201 is connected to the outlet of the primary air charging pipe 3203, which can better accelerate the movement of the material.

[0050] In some preferred embodiments of the present invention, the screw feeding device 32 further includes a rotary motor for driving the screw to rotate, and the rotary motor is connected to the top of the rotating shaft 3201 and is located outside the feeding tank 31 .

[0051] The upper part of the feeding and conveying pipeline 33 of the present invention is arranged in the feeding pipeline and extends to the height above the raw material bin 22 and is connected with the raw material bin 22 for feeding; that is, the upper part of the feeding and conveying pipeline 33 is inserted into the raw material bin 22 and the upper part of the feeding and conveying pipeline 33 is located above the raw material bin 22. The feeding and conveying pipeline 33 is used to convey materials into the crucible 200. The side wall of the feeding and conveying pipeline 33 located outside the furnace body 100 is sealed and connected to the furnace body 100, and the lower part of the feeding and conveying pipeline 33 has a side inlet and a bottom inlet; the bottom inlet is connected to a three-stage gas charging pipeline 3301 to introduce an inert gas carrier gas. More preferably, a three-stage gas charging valve 3302 is provided on the three-stage gas charging pipeline 3301. The three-stage gas charging pipeline 3301 is used to promote the feeding material to reach the crucible 200 completely by adding an inert gas carrier gas path to prevent the material from falling or backflowing. 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.

[0052] The side inlet is connected to the outlet of the feeding tank 31 through an intermediate feeding pipe 34. The intermediate feeding pipe 34 can be set according to the actual site and other requirements, for example, through one pipe, or through multiple pipes connected to each other and the multiple pipes are sequentially divided into a front pipe 3401, a rear pipe 3402, etc. along the material conveying direction.

[0053] When the intermediate feeding pipeline 34 is connected by two or more pipelines, the outlet end of the previous pipeline 3401 is extended into the inlet end of the next pipeline 3402 and a non-contact sealing sleeve is performed, and a secondary inflation pipeline 3403 is provided at the sealing sleeve. More preferably, a secondary inflation valve 3404 is provided on the secondary inflation pipeline 3403. The secondary inflation pipeline 3403 is used to prevent the material from flowing back into the previous pipeline 3401. The non-contact sealing sleeve means that the previous pipeline 3401 and the next pipeline 3402 are indirectly in contact through other components, not directly in contact.

[0054] In some preferred embodiments of the present invention, Figure 2As shown, the structure of the non-contact sealing sleeve includes a first bellows 38 and a sleeve 39, the sleeve 39 is sleeved on the outer surface of the outlet end of the previous pipe 3401 and extends to the outer surface of the inlet end of the next pipe 3402, the first bellows 38 is sleeved outside the sleeve 39 and the two ends extend outward respectively, and one end of the first bellows 38 is sleeved on the outer surface of the previous pipe 3401 and the other end is sleeved on the outer surface of the next pipe 3402, and the secondary inflation pipe 3403 is arranged on the end face of the first bellows 38 close to the previous pipe 3401. Preferably, the radial dimensions of the two end faces contained in the first bellows 38 and the sleeve 39 are different. The first bellows 38 can play a vacuum sealing role and also a shock absorbing role. 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.

[0055] In some preferred embodiments of the present invention, Figure 2 As shown, a second ball valve 36 capable of controlling the opening is provided near the outlet of the previous pipeline 3401 . The second ball valve 36 is used to control the amount of material entering the feeding and conveying pipeline 33 , thereby further improving the distribution uniformity of the material entering the crucible 200 .

[0056] 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 pipeline 33 and a gap is left between its edge and the inner wall of the crucible 200. The outlet of the feeding and conveying pipeline 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 pipeline 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 to form a tortuous logistics channel. When the material is conveyed by gas through the quantitative feeding device 300, the gas fluidity in the crucible 200 can be increased, and the content of particles in the gas is increased. 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) under the first guide plate 24 to prevent the particles (dust) from drifting to the crystal growth interface. The raw materials with larger particles will fall into the raw material bin 22 of the crucible 200. The porous graphite 23 can further promote the high-temperature gasification of the particles, thereby further improving the quality of crystal growth and reducing the probability that the material is transported to the crucible 200 and is not reacted in time and is 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 temperature of the crucible 200, thereby better ensuring the quality of crystal growth.

[0057] In some preferred embodiments of the present invention, the edge portion of the first guide plate 24 is U-shaped, and the suspended end portion of the third guide plate 26 vertically extends downward to the U-shaped portion of the first guide plate 24, forming a U-shaped tortuous logistics channel. During the rising process, the material needs to pass through the U-shaped tortuous logistics channel, which further extends the gas flow path and is conducive to promoting high-temperature gasification of particles.

[0058] 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, which is sleeved on the outer surface of the feeding and conveying pipe 33 and extends along the radial circumferential direction of 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 height of the second guide plate 25 is lower than the upper end height of the second guide plate 25, and the lower end of the second guide plate 25 at least extends to the upper part of the adjacent raw material bin 22. The second guide plate 25 with a specific structure can guide the added materials passing through the quantitative feeding device 300 into the raw material bin 22, further reducing the probability that the materials are transported to the crucible 200 and are entrained to the crystal growth surface without timely reaction.

[0059] 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 vertically extends to above an 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 .

[0060] 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 an evaporation and feeding gap 2701 is left 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 arranged near the top, the feeding through hole 3405 is arranged along the radial circumferential direction of the feeding and conveying pipe 33, the feeding through hole 3405 is located between the first guide plate 24 and the second guide plate 25, and 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 pipeline 33 can increase the evaporation area of ​​the silicon carbide raw material.

[0061] In some preferred embodiments of the present invention, the lower portion of the feeding and conveying pipeline 33 is connected to the tertiary inflation pipeline 3301 and the intermediate feeding pipeline 34 via 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 tertiary 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 pipeline raw material blockage.

[0062] 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.

[0063] 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 pipeline 33 and the tertiary inflation pipeline 3301, which can prevent large particles of raw materials from entering the tertiary inflation pipeline 3301 and allow gas to pass through the orifice plate 3407.

[0064] Further, such as Figure 4 As shown, the gas slip ring 37 includes a fixing part 3701, a sealing ring 3702, and an inert gas inlet 3703. The fixing part 3701 has a accommodating cavity and an inert gas inlet 3703 is arranged below the accommodating cavity. The inert gas inlet 3703 is communicated with the accommodating cavity. The lower part of the feeding and conveying pipeline 33 extends into the accommodating cavity and its side wall and the fixing part 3701 are sealed 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 communicated with 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 pipeline 33 in sequence from the three-stage filling pipeline 3301 through the inert gas inlet 3703, and the replenishment or addition of material enters the side inlet of the feeding and conveying pipeline 33 through the rear pipeline 3402 of the intermediate feeding pipeline 34, and is transported toward the crucible under the action of the inert gas carrier gas.

[0065] 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 respectively connected to the lifting drive mechanism and the first rotary drive mechanism. 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 move slowly 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.

[0066] 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 the weight change of the crystal, based on which the growth rate of the crystal is obtained, and further 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 realizing accurate control of the feeding.

[0067] The first weighing device 400 and the second weighing device 500 may be weighing devices in the prior art that can achieve the required functions.

[0068] 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; wherein the crucible support mechanism 600 is installed below the crucible 200 and is sleeved on the outer surface of the feeding and conveying pipe 33 through a bearing sleeve, and extends outward with the feeding and conveying pipe 33; the crucible lifting mechanism 700 is arranged outside the furnace body 100, and the crucible lifting mechanism 700 is connected to the outwardly extending part of the crucible support mechanism 600, and the connection is sealed with the furnace body 100 through a second bellows 71, which is used to drive the crucible support mechanism 600 to drive the crucible 200 to rise and fall. The second bellows 71 can be extended and retracted as the crucible 200 rises and falls while achieving sealing. It can be understood that the second bellows 71 is sleeved outside the crucible support mechanism 600 to achieve overall sealing.

[0069] In some preferred embodiments of the present invention, Figure 1 As shown, the silicon carbide growth furnace capable of quantitative feeding further includes a second rotation drive mechanism 800, which is arranged outside the furnace body 100; the second rotation drive mechanism 800 is connected to the outwardly extending portion of the crucible support mechanism 600, and is used to control the crucible 200 to rotate, so as to ensure the uniform heating of the crucible 200. The feeding and conveying pipeline 33 does not rotate, but the crucible 200 rotates, so that the raw materials can be evenly distributed in the crucible 200, the raw materials are evenly heated, and the heating and volatilization of the raw materials are facilitated.

[0070] In the present invention, when the crucible lifting mechanism 700 drives the crucible to lift, 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 drive the crucible 200 to rotate, 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. Exemplarily, the specific connection structure of the second rotary drive mechanism 800 and the crucible lifting mechanism 700 can refer to the corresponding connection of the prior art, as long as the required function can be achieved, for example, the crucible lifting mechanism 700 is connected to the worm gear reducer through a servo motor, the worm gear reducer is connected to the lead screw, the lead screw is connected to the slide, a linear slide rail for the crucible support mechanism 600 to slide is set on the slide, and the linear slide rail plays a guiding and weighing role, and the lead screw is used 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, and the rotation platform is driven by a servo motor to achieve circular rotation of the crucible supporting mechanism 600 driven by the rotation platform.

[0071] Furthermore, in some specific embodiments, the silicon carbide growth furnace capable of quantitative feeding may also include a lifting platform, which carries a feeding tank 31, so that the feeding tank 31 can move synchronously with the crucible 200 driven by the crucible support mechanism 600, which is beneficial to the stability of the feeding system. In order to ensure the stable lifting of the quantitative feeding device 300, the pipes contained therein can be softly connected, which is a mature existing technology and will not be described in detail here.

[0072] In some preferred embodiments of the present invention, Figure 1 and Figure 2 As shown, a first vacuum gauge 11 is disposed on the furnace body 100 , and a second vacuum gauge 3105 is also disposed on the feeding tank 31 , for testing the vacuum degree of the furnace body 100 or the feeding tank 31 .

[0073] 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, respectively, so as to control the relevant processes according to the required target parameters.

[0074] 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 further includes a heat preservation 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 of the side where the seed crystal is installed on the opposite side of the seed crystal installation part 21. The heat preservation shell 900 is located outside the crucible 200 and the feeding pipeline and inside the furnace body 100. The heater 91 is located between the heat preservation shell 900 and the crucible 200; and a vacuum port 12 is provided on the side of the furnace body 100. The seed crystal installation part 21 can be, for example, a crystal growth tray.

[0075] In a second aspect, the present invention provides a method for growing silicon carbide, which is carried out in the silicon carbide growth furnace capable of quantitative feeding as described in the first aspect.

[0076] The silicon carbide growth method includes: loading a first raw material into a raw material bin 22 of a crucible 200 in advance, and loading a second raw material into a 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.

[0077] The silicon carbide growth method further comprises: in the middle and / or late stages of crystal growth, feeding is performed through the quantitative feeding device 300, specifically, firstly, the vacuum degree in the feeding tank 31 is adjusted through the vacuum valve 3104 on the vacuum pipe 3102 in the quantitative feeding device 300, so that the vacuum degree in the feeding tank 31 is the same as the vacuum degree in the working chamber where the crucible 200 is located; then, the first ball valve 35 is opened to be at a target opening, the spiral member is controlled to rotate to drive the second raw material to move downward, and at the same time, the gas supply valve 3103, the first-stage gas charging valve 3204, and the second-stage gas charging valve 3205 are opened. The gas from the inflation valve 3404, the third-level inflation valve 3302, and the first-level inflation valve 3204 flows into the spiral 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, and enters the feeding conveying pipe 33 under the pressure difference between the crucible 200 and the feeding tank 31, and the gas supply from the third-level inflation valve 3302 further promotes the second raw material to enter the feeding conveying pipe 33, thereby reaching the crucible 200 to replenish the raw material bin 22 in the crucible 200.

[0078] In some preferred embodiments of the present invention, in terms of atomic percentage, the Si / C in the first raw material is in the range of 0.8-0.95, and the Si / C in the second raw material is in the range of 1.05-1.2; using the first raw material and the second raw material of appropriate composition can make the Si / C atomic ratio in the gas phase in the crucible 200 closer to 1.0 during the entire crystal growth process, which is more conducive to improving the quality of silicon carbide crystals.

[0079] In some preferred embodiments of the present invention, the particle diameter of the first raw material is 5 mm-10 mm.

[0080] In some preferred embodiments of the present invention, the particle diameter of the second raw material is 4 mm to 8 mm. The particle diameter of the silicon-rich second raw material is in the above-mentioned suitable range, which can effectively prevent the raw material from forming dust in the crucible 200, and the dust may drift to the crystal growth surface before it sublimates and form inclusion defects, and is convenient for pipeline transportation.

[0081] 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.

[0082] In some preferred embodiments of the present invention, the silicon carbide growth method further comprises step a, when adding materials, controlling the crucible support mechanism 600 to drive the crucible 200 to rotate through the second rotation drive mechanism 800. This is more conducive to the uniform distribution of the added materials, and the silicon carbide raw materials are heated quickly, accelerating the solid-gas conversion.

[0083] 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 internal quality defects.

[0084] In some preferred embodiments of the present invention, the silicon carbide growth method also 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 scheme makes the Si / C atomic ratio in the gas phase in the crucible 200 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.

[0085] In some specific embodiments of the present invention, a method for growing silicon carbide, in the Figure 1 , Figure 2 and Figure 3 The silicon carbide growth furnace shown is carried out, including: 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 feed tank 31. According to the test values ​​of the first vacuum gauge 11 and the second vacuum gauge 3105, the vacuum degree of the working chamber in the furnace body 100 where the crucible 200 is located is compared with the vacuum degree in the feeding tank 31 through the PLC controller. When the two are equal, the vacuum valve 3104 for evacuating the vacuum on the feeding tank 31 is closed, and the first-level charging valve 3204 and the air supply valve 3103 are opened in sequence to the required openings respectively; the rotating motor is started, and the rotating motor drives the rotating shaft 3201 in the spiral element, and the spiral element drives the second raw material to move downward, and at the same time, the first-level charging valve 3204, the air supply valve 3103, and the second-level charging valve 3404 are opened, and the gas of the first-level charging valve 3204 flows into the ventilation channel in the spiral feeding device 32 through the air slip ring 37, and then blows into the feeding tank 31 through the air hole connected to the ventilation channel, so as to accelerate 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 role in shock absorption and vacuum sealing. 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 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. The second raw material reaches the bottom of the feeding and conveying pipeline 33. Due to the pressure difference between the feeding tank 31 and the crucible 200, a part of the second raw material flows into the crucible 200. Some particles with large mass will fall on the orifice plate 3407. At this time, the three-stage gas filling valve 3302 below is opened, and the inert gas from the three-stage gas filling pipeline 3301 along the pipeline reaches the bottom of the orifice plate 3407, which can lift and transport larger particles to the feeding and conveying pipeline 33. In order to prevent the micro particles from not sublimating after reaching the crucible 200 and adhering to the crystal with the gas, the first guide plate 24, the third guide plate 26 and the porous graphite 23 are added to the crucible 200. The first guide plate 24 and the third guide plate 26 form a maze structure, which blocks the particles (dust) below the first guide plate 24, prevents the particles (dust) from drifting to the crystal growth surface, and the larger particles of raw materials will fall into the crucible 200.

[0086] The feeding and conveying pipe 33 remains stationary during feeding, and the crucible support mechanism 600 is driven by the second rotation drive mechanism 800 to drive the crucible 200 to rotate. The feeding and conveying pipe 33 is connected to the crucible support mechanism 600 through a bearing. The crucible 200 rotates slowly, and the second raw material is evenly distributed in the raw material bin 22 at the bottom of the crucible 200 along the second guide plate 25. As the crystal continues to thicken, the crystal also moves slowly upward, keeping the growth interface of the crystal unchanged, so that the crystal growth continues, which can solve the problem of small crystal thickness due to insufficient raw materials.

[0087] Furthermore, the present invention can also configure the silicon carbide seed crystal with lifting, rotating and weighing functions through the lifting shaft 28, the lifting drive mechanism, the first rotating 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 weight of the crystal, 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.

[0088] The present invention can realize the growth of silicon carbide crystals with a thickness of more than 100 mm.

[0089] In the prior art, the silicon carbide growth furnace cannot be charged, but can only add ordinary raw materials with an atomic ratio of Si and C of 1:1 into the crucible 200, and then directly grow the crystal, and the thickness of the obtained silicon carbide crystal is basically below 30mm. However, the silicon carbide growth furnace capable of specific quantitative charging and the silicon carbide growth method of the present invention adopt the complementarity of the first raw material and the second raw material, and quantitative charging in the middle and / or late stages of crystal growth, and the thickness of the obtained silicon carbide crystal can be above 100mm, which is significantly higher than the thickness and quality of the silicon carbide crystal obtained by the silicon carbide growth furnace of the prior art.

[0090] 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 growth furnace capable of quantitative feeding, comprising a furnace body and a crucible, wherein a seed crystal mounting portion is arranged 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 comprises a spiral member, the spiral member has a ventilation channel, and 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 member; the inlet of the ventilation channel is connected with a primary air charging pipeline; A feeding pipeline is provided at the lower part of the crucible, and the feeding pipeline 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 pipeline and the inner wall of the crucible; the upper part of the feeding and conveying pipeline is arranged in the feeding pipeline and extends to above the height of the raw material bin and is connected with the raw material bin for feeding; the side wall of the feeding and conveying pipeline located outside the furnace body is sealedly connected with the furnace body, and the lower part of the feeding and conveying pipeline has a side inlet and a bottom inlet; the bottom inlet is connected with a three-stage gas charging pipeline to introduce an inert gas carrier gas; The side inlet is connected to the outlet of the feeding tank through an intermediate feeding pipe, and a first ball valve capable of controlling the opening is arranged 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 subsequent pipe and a non-contact sealing sleeve is performed, and a secondary inflation pipe is arranged at the sealing sleeve.

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 divides 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 pipeline and a gap is left between its edge and the inner wall of the crucible. The outlet of the feeding and conveying pipeline 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 pipeline. 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.

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 to form 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 pipeline and extends along the radial circumferential direction of the feeding and conveying pipeline. The second guide plate is located below the top outlet of the feeding and conveying pipeline 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 pipeline 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 can enter the evaporation and feeding gap through the spacer sleeve after evaporation; and the top of the feeding and conveying pipeline is sealed and a feeding through hole is arranged near the top, the feeding through holes are arranged along the radial circumferential direction of the feeding and conveying pipeline, 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.

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-shaped plate vertically extends to the top of 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 part 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 part 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: A perforated plate for blocking raw material particles is arranged between the bottom inlet of the feeding and conveying pipeline and the third-stage aeration pipeline, and / or, The spiral member extends to an outlet near the feeding tank; 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 holes are arranged 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.

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 degree is arranged near the outlet of the previous pipeline, and / or, The non-contact sealing sleeve structure 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 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; and / or, The silicon carbide growth furnace capable of quantitative feeding also includes a crucible supporting mechanism, a crucible lifting mechanism and a second rotating driving 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 outwardly with the feeding and conveying pipe; the crucible lifting mechanism and the second rotating driving mechanism are respectively arranged outside the furnace body, the crucible lifting mechanism is connected to the outwardly extending part of the crucible supporting mechanism and the connection is sealed with the furnace body by a second bellows, which is used to drive the crucible supporting mechanism to drive the crucible to lift and lower; the second rotating driving 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 arranged on the furnace body, and a second vacuum gauge is also arranged on the feeding tank; a gas supply valve is arranged on the gas supply pipeline, a vacuum valve is arranged on the vacuum pipeline, a first-level gas charging pipeline is arranged with a first-level gas charging valve, a third-level gas charging pipeline is arranged with a third-level gas charging valve, and a second-level gas charging pipeline is arranged with a second-level gas charging valve; and the silicon carbide growth furnace capable of quantitative feeding also includes a PLC controller, and the PLC controller 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 a side of a seed crystal installed on the opposite side of a seed crystal installation portion, wherein 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 pipeline 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 in advance, and loading a second raw material into a feeding tank; 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 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 pipeline, the first-level air charging valve on the first-level air charging pipeline, the second-level air charging valve on the second-level air charging pipeline, and the third-level air charging valve on the third-level air charging pipeline 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 pipeline, and enters the feeding conveying pipeline 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 pipeline, thereby reaching the crucible, and the raw material bin in the crucible is fed with feed.

13. The method for growing silicon carbide according to claim 12, characterized in that: 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 10-50Pa.

14. The method for growing silicon carbide 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 replenishing materials, controlling the crucible support mechanism through the second rotation drive mechanism to drive the crucible to rotate; Step b, during the crystal growth process, the weight change of the growing crystal is measured by a second weighing device to obtain the change of the crystal thickness; according to the change of the crystal thickness, the seed crystal is moved upward by the 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 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 feed amount.

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