Crucible device for growing silicon carbide crystals with extremely low inclusions and use method of crucible device
By combining the placement of porous graphite structures on graphite crucibles and replenishing silicon in the late growth stage, the problem of carbon encapsulation defects in silicon carbide crystals is solved, and high-quality and low-cost silicon carbide crystal growth is achieved.
Patent Information
- Application Number
- CN202510276898.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-06-06
AI Technical Summary
Silicon carbide crystals grown in the prior art are prone to carbon-wrapped defects, affecting crystal quality, and the existing solutions are expensive and difficult to produce on a large scale.
A third graphite ring, a porous graphite sheet and a porous graphite flow cylinder are placed on the graphite crucible to optimize the transmission direction of the growth air flow, and a groove is provided in the first graphite ring to supplement silicon in the middle and late stages of silicon carbide crystal growth to suppress the imbalance of the C/Si ratio.
It effectively reduces the carbon coating content in silicon carbide crystals, improves crystal quality, and reduces production costs, making it suitable for commercial scale production.
Smart Images
Figure CN120099626A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor material preparation, and in particular to a crucible device for growing extremely low inclusion silicon carbide crystals and a use method thereof. Background Art
[0002] Physical Vapor Transport (PVT) is the most widely used commercial method for growing silicon carbide crystals. The principle of this method is to place silicon carbide powder at the bottom of a graphite crucible, a silicon carbide seed crystal at the top of the crucible, and an insulation layer wrapped around the outside of the graphite crucible. The graphite crucible is then heated to above 2000 degrees Celsius in a vacuum environment. The silicon carbide powder sublimates from a solid state to a gas state, and is driven by a temperature gradient to deposit on the seed crystal at the top of the crucible to complete crystal growth. However, the silicon carbide crystals grown in the current crucible thermal field structure are prone to carbon encapsulation defects, which have a great impact on the quality of the silicon carbide crystals. Therefore, how to reduce the carbon encapsulation defects of the grown silicon carbide crystals is a technical problem that needs to be solved urgently.
[0003] During the growth of silicon carbide crystals by the PVT method, the sources of carbon inclusions are mainly the following two aspects: 1. In the early stage of growth, the silicon carbide powder at the bottom of the crucible sublimates, and the Si content in the gas phase component is relatively high, which seriously corrodes the inner wall of the crucible. The severely corroded graphite is transformed into a loose and porous state, which is easy to follow the airflow and deposit on the crystal growth surface to form carbon inclusions; 2. In the middle and late stages of growth, the sublimation loss of silicon carbide powder at the bottom of the crucible gradually increases, the C / Si ratio in the gas phase component increases, the powder is seriously graphitized, and the carbon particles in the powder are easy to follow the airflow and deposit on the crystal growth surface to form carbon inclusions. For problem 1, the current solution is to coat the inner wall surface with a layer of corrosion-resistant and highly stable film, such as niobium carbide and tantalum carbide, to isolate the atmosphere and protect the graphite. However, this method has high technical requirements and high costs. The consistency of film thickness and quality is difficult to control, and it is difficult to use for commercial large-scale production. For question 2, a common solution is to place a multi-layer porous mesh structure on the surface of the powder, filter the atmosphere sublimated from the powder, and then transfer it to the seed crystal for growth. The problem with this method is that the introduced porous structure itself, as a carbon source, will also be corroded by the silicon-rich atmosphere, bringing carbon inclusions into the crystal.
[0004] CN118461142A discloses a double crucible silicon carbide crystal growth device and method based on liquid phase method, including: a furnace body; a first crucible, arranged in the furnace body, and a plurality of first flow channels are opened on the inner side wall of the first crucible along the circumference of the first crucible; a second crucible, embedded in the first crucible, and the second crucible can move along the height direction of the furnace body, and a plurality of second flow channels are opened on the inner side wall of the second crucible, and the second flow channels correspond to and are connected with the first flow channels one by one, and a first chamber is formed between the bottom wall of the second crucible and the first crucible; a lifting device is connected to the second crucible, and the lifting device is used to drive the second crucible to move along the height direction of the furnace body; a heating assembly is used to heat the first crucible and the second crucible. Through the double crucible silicon carbide crystal growth device based on the liquid phase method, the evaporation effect of the solution can be suppressed and the stability of the long-term growth of the crystal can be improved; at the same time, by setting a raw material replenishing tube, the consumed solute can be replenished in time during the growth process, so that the mixed solution for the growth of silicon carbide crystals in the first crucible can maintain the best ratio state.
[0005] CN117737835A discloses a double-crucible silicon carbide crystal growth device and method, the device includes a heat preservation cylinder, a first crucible, a second crucible, a heating structure and a lifting rod, the heat preservation cylinder includes a cylinder body and a partition, the partition is openably and closably arranged in the cylinder body, the first crucible is arranged in the cylinder body and is located above the partition, a first graphite cylinder is arranged in the first crucible, the first graphite cylinder passes through the bottom wall of the first crucible, the second crucible is arranged in the cylinder body and is located below the partition, a second graphite cylinder is arranged in the second crucible, the second graphite cylinder is located on the bottom wall of the first crucible, the heating structure is located in the cylinder body, and is used to heat the first crucible and the second crucible, a seed crystal for growing silicon carbide crystals is arranged at the bottom of the lifting rod, and when the partition is opened, the seed crystal can be selectively moved to the first crucible or the second crucible under the drive of the lifting rod.
[0006] CN210974929U discloses a crucible for silicon carbide crystal growth and a silicon carbide crystal growth device, the crucible for silicon carbide crystal growth includes a crucible body and a graphite rod, the crucible body has a receiving cavity, the receiving cavity has a growth raw material area for receiving silicon carbide crystal growth raw materials; the graphite rod is arranged in the receiving cavity, and at least part of the graphite rod is located in the growth raw material area. The arrangement of the graphite rod can avoid the formation of a large number of recrystallized polycrystalline silicon carbide areas in the middle axial area of the crucible body, improve the utilization rate of the growth raw materials, and the graphite rod can also enhance the heat distribution of induction heating, so that the temperature field distribution of the growth raw materials in the crucible body is more uniform, which is conducive to the growth of the crystal, thereby solving the technical problem of low utilization rate of silicon carbide crystal growth raw materials in the prior art.
[0007] However, there are still many carbon inclusions in the silicon carbide crystals obtained by the above silicon carbide crystal growth device. Summary of the invention
[0008] In view of the problems existing in the prior art, the present invention provides a crucible device and a method for using the crucible for growing extremely low inclusion silicon carbide crystals, by placing a third graphite ring, a porous graphite sheet, and a porous graphite guide tube in combination on a graphite crucible, optimizing the transmission and guidance of the growing airflow; and arranging a groove in the first graphite ring, only supplementing silicon in the middle and late stages of silicon carbide crystal growth, suppressing the imbalance of the C / Si ratio in the late stages of growth, and thus effectively reducing the generation of carbon inclusions. The crucible device of the present invention has a simple structure and a reasonable design, and solves the problem of more carbon inclusions in the existing preparation of silicon carbide crystals.
[0009] To achieve this object, the present invention adopts the following technical solutions:
[0010] In a first aspect, the present invention provides a crucible device for growing extremely low inclusion silicon carbide crystals, the crucible device comprising a graphite cover, a first graphite ring, a second graphite ring, a third graphite ring and a graphite crucible arranged in sequence from top to bottom;
[0011] A groove is provided in the first graphite ring; a right truncated cone space is formed in the middle of the first graphite ring;
[0012] A porous graphite ring and a porous graphite guide tube are sequentially arranged inside the second graphite ring; the porous graphite guide tube is in the shape of an inverted frustum;
[0013] The porous graphite guide tube is arranged above the porous graphite sheet; the porous graphite sheet is nested in the third graphite ring.
[0014] The porous graphite rings, porous graphite sheets, and porous graphite guide tubes combined and placed on the graphite crucible in the crucible device for growing extremely low inclusion silicon carbide crystals described in the present invention can optimize the transmission guidance of the growing airflow and reduce the generation of inclusions. Moreover, the porous graphite sheets and porous graphite rings will be induced to heat when using medium-frequency induction heating, which can effectively reduce the temperature gradient inside the powder, thereby reducing the corrosion of the inner wall of the first graphite ring and effectively reducing carbon inclusions during the growth process. In addition, the first graphite ring of the present invention is provided with a groove, and the groove is filled with silicon carbide powder, which can supplement silicon in the middle and late stages of silicon carbide crystal growth, suppress the imbalance of the C / Si ratio in the late stages of growth, and can also effectively reduce the generation of carbon inclusions.
[0015] Preferably, the top of the first graphite ring is threadedly connected to the graphite cover.
[0016] Preferably, the first graphite ring is threadedly connected to the second graphite ring.
[0017] Preferably, the second graphite ring is threadedly connected to the graphite crucible.
[0018] Preferably, the porous graphite ring is composed of equally divided circular arc segments.
[0019] Preferably, the number of equally divided circular arc segments is at least 6, for example, 6, 7, 8 or 9 segments.
[0020] The porous graphite ring of the present invention is preferably composed of 6 equally divided arc segments. There is a cavity below the porous graphite ring, that is, between the porous graphite guide tube and the second graphite ring, which is convenient for the silicon carbide powder stored in the groove of the first graphite ring to fall to the surface of the porous graphite sheet, so as to achieve the purpose of silicon supplementation in the later stage and reduce the generation of carbon inclusions.
[0021] Preferably, the thickness of the porous graphite ring is 0.5-3 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 2 mm or 3 mm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0022] Preferably, the thickness of the porous graphite sheet is 0.5-5 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm or 5 mm, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0023] Preferably, the thickness of the porous graphite guide tube is 0.5-5 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm or 5 mm, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0024] The present invention preferably has a thickness of 0.5 to 3 mm for the porous graphite ring, a thickness of 0.5 to 5 mm for the porous graphite sheet, and a thickness of 0.5 to 5 mm for the porous graphite guide tube. The porous graphite ring, the porous graphite sheet, and the porous graphite guide tube can slow down the airflow velocity of the sublimated silicon carbide powder in the early stage of silicon carbide crystal growth, filter the gas phase components, and reduce the generation of carbon inclusions.
[0025] Preferably, the density of the graphite in the first graphite ring, the second graphite ring and the third graphite ring is independently 1.7 to 2.2 g / cm 3 , for example, it can be 1.7 g / cm 3 , 1.75g / cm 3 , 1.8g / cm 3 , 1.85g / cm 3 , 1.9g / cm 3 , 2g / cm 3 or 2.2g / cm 3etc., but are not limited to the listed values, and other values not listed within the numerical range are also applicable;
[0026] The porosity is independently 5% to 20%, for example, 5%, 8%, 10%, 13%, 15%, 18% or 20%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0027] Preferably, the density of the porous graphite in the porous graphite ring, the porous graphite guide tube and the porous graphite sheet is independently 1 to 1.5 g / cm 3 , for example, it can be 1g / cm 3 , 1.1g / cm 3 , 1.15g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 or 1.5g / cm 3 etc., but are not limited to the listed values, and other values not listed within the numerical range are also applicable;
[0028] The porosity is independently 30% to 60%, for example, 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0029] In the present invention, the density of the graphite in the first graphite ring, the second graphite ring and the third graphite ring is preferably independently 1.7 to 2.2 g / cm 3 The porosity is independently 5% to 20%; the density of the porous graphite in the porous graphite ring, porous graphite guide tube and porous graphite sheet is independently 1 to 1.5 g / cm 3 , the porosity is independently 30% to 60%, which plays a role in optimizing the transmission and guidance of the growth gas flow and reducing the generation of inclusions. In addition, in the middle and late stages of silicon carbide crystal growth, the porous graphite rings and porous graphite sheets are easily corroded by the gas phase and become loose and porous, so that the silicon carbide powder stored in the first graphite ring falls to the surface of the porous graphite sheet to supplement silicon, further reducing the generation of carbon inclusions.
[0030] In a second aspect, the present invention further provides a method for using the crucible device for growing extremely low inclusion silicon carbide crystals as described in the first aspect, the method comprising:
[0031] (1) Place the seed crystal below the graphite cover, and load silicon carbide powder into the groove of the first graphite ring and the graphite crucible; place the third graphite ring and the second graphite ring on the upper part of the graphite crucible in sequence, and place a porous graphite ring and a porous graphite guide cylinder inside the second graphite ring in sequence;
[0032] (2) Use an intermediate frequency induction power supply to heat the graphite crucible. The silicon carbide powder in the graphite crucible sublimes, passes through the porous graphite sheet and the porous graphite guide cylinder in sequence, and then deposits on the surface of the seed crystal to realize the initial growth of the silicon carbide crystal;
[0033] (3) In the middle and later stages of the growth of the silicon carbide crystal, the overall height of the porous graphite guide cylinder decreases, and the silicon carbide powder in the groove of the first graphite ring falls onto the surface of the porous graphite sheet through the porous graphite ring and finally falls into the graphite crucible for silicon replenishment, obtaining a silicon carbide crystal with extremely low inclusions;
[0034] The inclusion content in the silicon carbide crystal with extremely low inclusions is less than 5 per slice.
[0035] The method for using the crucible device for growing silicon carbide crystals with extremely low inclusions according to the present invention uses intermediate frequency induction heating. At this time, the temperature at the edge of the crucible is high during the crystal growth process, the sublimation rate of the silicon carbide powder is fast, and the gas flow rate is relatively fast in the initial stage of the growth of the silicon carbide crystal. The present invention combines and places a third graphite ring, a porous graphite sheet, and a porous graphite guide cylinder on the graphite crucible to optimize the transmission and guidance of the growth gas flow and reduce the generation of inclusions. Among them, the third graphite ring can effectively block the turbulent flow rising along the edge of the graphite crucible and guide it to the edge of the porous graphite sheet. The gas flow converges and rises here, and then slows down through the porous graphite guide cylinder, and deposits on the surface of the seed crystal together with the atmosphere sublimating and rising from the center of the porous graphite sheet to realize growth. The gas flow is stable, and the gas phase components are filtered by the porous graphite sheet, which can block the carbon particles transmitted from the material source. In addition, when using an intermediate frequency induction power supply for heating, the porous graphite sheet and the porous graphite ring arranged in the middle section of the crucible device are heated by induction, which can effectively reduce the temperature gradient inside the powder. After testing, when the temperature at the temperature measurement point in the center of the graphite cover remains unchanged, compared with not adding the porous graphite sheet and the porous graphite ring, the axial temperature gradient inside the silicon carbide powder can be reduced by 20 °C, and the overall temperature inside the silicon carbide powder is higher; in addition, the axial temperature difference in the growth chamber between the seed crystal and the porous graphite sheet can also be reduced by 10%. When the temperature at the temperature measurement point remains unchanged, the overall temperature inside the crucible device increases, the C / Si ratio increases with the increase of the temperature, the rich silicon atmosphere in the initial stage of growth is controlled, the corrosion of the inner wall of the first graphite ring can be reduced, and the carbon inclusions in the growth process can be effectively reduced.
[0036] In the present invention, as the induction heating proceeds, the silicon carbide powder in the graphite crucible is severely graphitized, the C / Si ratio gradually increases and becomes unbalanced, and the inclusions begin to increase. At this time, the porous graphite guide tube and the porous graphite sheet are subjected to the gas phase corrosion of the high velocity airflow generated in the middle of the entire crucible device and become loose and porous, and the overall height of the porous graphite guide tube will decrease, unable to support the porous graphite ring and the silicon carbide powder in the first graphite ring, and the porous graphite ring is petal-shaped, which will tilt and cause the silicon carbide powder stored in the first graphite ring to fall to the surface of the porous graphite sheet, and fall into the graphite crucible through the pores of the porous graphite sheet to supplement silicon, thereby reducing the generation of carbon inclusions.
[0037] The silicon carbide crystal with extremely low inclusions in step (3) of the present invention has an inclusion content of less than 5 per piece, for example, 4 per piece, 3 per piece, 2 per piece, 1 per piece or 0 per piece.
[0038] Compared with the prior art, the present invention has at least the following beneficial effects:
[0039] (1) The crucible device for growing extremely low inclusion silicon carbide crystals provided by the present invention utilizes a third graphite ring, a porous graphite sheet and a porous graphite guide tube placed in combination on a graphite crucible to optimize the flow direction and flow rate of the growth gas flow, thereby reducing carbon inclusions during the growth process;
[0040] (2) The crucible device for growing extremely low inclusion silicon carbide crystals provided by the present invention provides a groove for storing silicon carbide powder in the first graphite ring, thereby replenishing silicon in the middle and late stages of silicon carbide crystal growth, suppressing the imbalance of the C / Si ratio in the late stages of growth, and reducing the generation of carbon inclusions;
[0041] (3) The present invention provides a method for using a crucible device for growing extremely low inclusion silicon carbide crystals. The method uses medium frequency induction heating to cause induction heating of porous graphite sheets and porous graphite rings, thereby reducing the temperature gradient inside the silicon carbide powder, thereby reducing corrosion to the inner wall of the first graphite ring, and effectively reducing the generation of carbon inclusions. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Figure 1 It is a schematic structural diagram of a crucible device for growing extremely low inclusion silicon carbide crystals in a specific embodiment of the present invention.
[0043] In the figure: 1-graphite cover; 2-first graphite ring; 3-second graphite ring; 4-third graphite ring; 5-graphite crucible; 6-porous graphite ring; 7-porous graphite guide tube; 8-porous graphite sheet; 9-groove;
[0044] The triangles in the figure represent silicon carbide powder. DETAILED DESCRIPTION
[0045] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.
[0046] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.
[0047] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.
[0048] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.
[0049] As a specific embodiment of the present invention, a crucible device for growing extremely low inclusion silicon carbide crystals is provided, and its structural schematic diagram is shown as follows: Figure 1 shown.
[0050] The crucible device comprises a graphite cover 1, a first graphite ring 2, a second graphite ring 3, a third graphite ring 4 and a graphite crucible 5 which are arranged in sequence from top to bottom;
[0051] A groove 9 is provided in the first graphite ring 2; a right truncated cone space is formed in the middle of the first graphite ring 2;
[0052] A porous graphite ring 6 and a porous graphite guide tube 7 are sequentially arranged in the second graphite ring 3; the porous graphite guide tube 7 is in the shape of an inverted truncated cone;
[0053] The porous graphite guide tube 7 is arranged above the porous graphite sheet 8 ; the porous graphite sheet 8 is nested in the third graphite ring 4 .
[0054] The top of the first graphite ring 2 is threadedly connected to the graphite cover 1;
[0055] The first graphite ring 2 is threadedly connected to the second graphite ring 3;
[0056] The second graphite ring 3 is threadedly connected to the graphite crucible 5 .
[0057] The porous graphite ring 6 is composed of 6 equally divided arc segments; the thickness of the porous graphite ring 6 is 3 mm.
[0058] The thickness of the porous graphite sheet 8 is 0.5 mm;
[0059] The thickness of the porous graphite guide tube 7 is 3 mm.
[0060] The density of graphite in the first graphite ring 2, the second graphite ring 3 and the third graphite ring 4 is 1.7 g / cm 3 , the porosity is 20%;
[0061] The density of the porous graphite in the porous graphite ring 6, the porous graphite guide tube 7 and the porous graphite sheet 8 is 1 g / cm 3 , the porosity is 50%.
[0062] As a specific embodiment of the present invention, a method for using the above-mentioned crucible device for growing extremely low inclusion silicon carbide crystals is also provided, and the method for using comprises:
[0063] (1) placing a seed crystal under the graphite cover 1, and loading silicon carbide powder into the groove 9 of the first graphite ring 2 and the graphite crucible 5; placing a third graphite ring 4 and a second graphite ring 3 in sequence on the upper part of the graphite crucible 5, and placing a porous graphite ring 6 and a porous graphite guide tube 7 in sequence on the inner side of the second graphite ring 3;
[0064] (2) using a medium frequency induction power supply to heat the graphite crucible 5, the silicon carbide powder in the graphite crucible 5 is sublimated, and then passes through the porous graphite sheet 8 and the porous graphite guide tube 7 in sequence and then deposits on the surface of the seed crystal to achieve the initial growth of the silicon carbide crystal;
[0065] (3) In the middle and late stages of the growth of silicon carbide crystals, the overall height of the porous graphite guide tube 7 decreases, and the silicon carbide powder in the groove 9 of the first graphite ring 2 falls through the porous graphite ring 6 to the surface of the porous graphite sheet 8 and finally falls into the graphite crucible 5 for silicon replenishment, thereby obtaining silicon carbide crystals with extremely low inclusions.
[0066] The silicon carbide crystal with extremely low inclusions obtained in this specific embodiment has an inclusion content of 2 per piece.
[0067] In summary, the crucible device for growing extremely low inclusion silicon carbide crystals provided by the present invention effectively reduces the carbon coating content in silicon carbide crystals from three aspects: first, the flow direction and flow rate of the airflow generated by the sublimation of silicon carbide powder are optimized; second, silicon is supplemented in the middle and late stages of silicon carbide crystal growth; third, medium frequency induction heating is used to reduce the temperature gradient inside the silicon carbide powder, and finally silicon carbide crystals with extremely low inclusions are obtained. The crucible device of the present invention has a reasonable structural design and a simple method of use, and is suitable for large-scale promotion and application.
[0068] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
[0069] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.
Claims
1. A crucible device for growing extremely low inclusion silicon carbide crystals, characterized in that: The crucible device comprises a graphite cover, a first graphite ring, a second graphite ring, a third graphite ring and a graphite crucible which are arranged in sequence from top to bottom; A groove is provided in the first graphite ring; a right truncated cone space is formed in the middle of the first graphite ring; A porous graphite ring and a porous graphite guide tube are sequentially arranged inside the second graphite ring; the porous graphite guide tube is in the shape of an inverted frustum; The porous graphite guide tube is arranged above the porous graphite sheet; the porous graphite sheet is nested in the third graphite ring.
2. The crucible device according to claim 1, characterized in that The top of the first graphite ring is threadedly connected to the graphite cover; Preferably, the first graphite ring is threadedly connected to the second graphite ring; Preferably, the second graphite ring is threadedly connected to the graphite crucible.
3. The crucible device according to claim 1 or 2, characterized in that: The porous graphite ring is composed of equally divided circular arc segments.
4. The crucible device according to claim 3, characterized in that: The number of the equally divided arc segments is at least 6.
5. The crucible device according to any one of claims 1 to 4, characterized in that: The thickness of the porous graphite ring is 0.5-3 mm.
6. The crucible device according to any one of claims 1 to 5, characterized in that: The thickness of the porous graphite sheet is 0.5-5 mm.
7. The crucible device according to any one of claims 1 to 6, characterized in that: The thickness of the porous graphite guide tube is 0.5-5 mm.
8. The crucible device according to any one of claims 1 to 7, characterized in that: The density of the graphite in the first graphite ring, the second graphite ring and the third graphite ring is independently 1.7 to 2.2 g / cm 3 , the porosity is independently 5% to 20%.
9. The crucible device according to any one of claims 1 to 8, characterized in that: The density of the porous graphite in the porous graphite ring, the porous graphite guide tube and the porous graphite sheet is independently 1 to 1.5 g / cm 3 , the porosity is independently 30% to 60%.
10. A method for using the crucible device for growing extremely low inclusion silicon carbide crystals according to any one of claims 1 to 9, characterized in that: The method of use includes: (1) placing a seed crystal under a graphite cover, and loading silicon carbide powder into the groove of a first graphite ring and a graphite crucible; placing a third graphite ring and a second graphite ring on the upper part of the graphite crucible in sequence, and placing a porous graphite ring and a porous graphite guide tube on the inner side of the second graphite ring in sequence; (2) using a medium frequency induction power supply to heat the graphite crucible, the silicon carbide powder in the graphite crucible is sublimated, and then passes through the porous graphite sheet and the porous graphite guide tube in sequence and then is deposited on the surface of the seed crystal to achieve the initial growth of the silicon carbide crystal; (3) In the middle and late stages of silicon carbide crystal growth, the overall height of the porous graphite guide tube decreases, and the silicon carbide powder in the groove of the first graphite ring falls through the porous graphite ring to the surface of the porous graphite sheet and finally falls into the graphite crucible for silicon replenishment, thereby obtaining silicon carbide crystals with extremely low inclusions; The silicon carbide crystal with extremely low inclusions has an inclusion content of less than 5 per piece.