Silicon carbide preparation device and process

Abstract

The present invention belongs to the technical field of silicon carbide, and in particular relates to a novel silicon carbide preparation device and process, comprising: an inner crucible, in which silicon carbide powder raw material is arranged; an outer guide tube, which is arranged at the upper part of the inner crucible, and the outer guide tube is communicated with the inner crucible; an inner guide tube, which is located inside the outer guide tube, silicon powder is arranged between the inner guide tube and the outer guide tube, and the inner guide tube is suspended above the inner crucible; a growth crucible, which is located outside the inner crucible and the outer guide tube, and the growth crucible is communicated with the upper part of the outer guide tube; a growth base, which is located between the inner crucible and the growth crucible, a seed crystal is arranged on the growth base, and the growth base is installed at the bottom of the growth crucible. The silicon carbide preparation device and process described in the present invention can prepare large-sized, high-quality silicon carbide crystals by physical vapor deposition.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon carbide, and in particular relates to a novel silicon carbide preparation device and process. Background Art

[0002] Silicon carbide, the third-generation semiconductor, is a single crystal grown at high temperature. Its hardness is second only to diamond and its melting point is 2830°C. Silicon carbide has the characteristics of wide bandgap, high thermal conductivity, high critical breakdown field strength, high electron saturation drift rate, etc. It is a popular material for preparing high-temperature, high-frequency, and high-power devices. Silicon carbide crystals are widely used in electric vehicles, hybrid vehicles, rail transit, high-frequency devices, microwave devices, communications, aerospace and other fields, and their economic benefits and national defense value are very high.

[0003] As a high temperature resistant material, the preparation of silicon carbide crystals first involves heating quartz sand, coke, sawdust and other raw materials to above 2500°C and calcining to obtain silicon carbide powder; then, large single crystals are obtained by sintering the powder, physical vapor deposition or solvent method. Among them, high-quality large-size single crystals or polycrystalline materials with large single crystals are mainly prepared by physical vapor deposition, but the physical vapor deposition method (PVT method) has high temperature, uneven temperature field, low efficiency, and defects such as microtubes in silicon carbide crystals. At present, this method is mainly used in the semiconductor field, and the size of the silicon carbide crystals prepared by it is also mainly limited to less than 6 inches. Therefore, the technology for efficiently and quickly preparing large-scale silicon carbide crystals with excellent quality is not yet mature.

[0004] In addition, when growing silicon carbide crystals using the PVT method, the seed crystals are generally fixed to the top of the growth crucible by adhesives or seed crystal clamps. The external force applied in this way will cause stress in the silicon carbide seed crystals, and eventually cause defects in the silicon carbide crystals, thereby affecting the quality of the silicon carbide crystals.

[0005] Furthermore, from the silicon-carbon binary phase diagram, it is known that silicon carbide crystal growth cannot be directly solidified from a single liquid due to its high melting point, and can only be obtained by sublimating silicon carbide powder between 1900 and 2400°C. Therefore, during the implementation of the PVT method, the silicon carbide source needs to be placed in a crucible and heated to above 2000°C so that the non-stoichiometric silicon carbide source is sublimated and transported to the inside of the cavity, including the surface of the silicon carbide seed crystal, for crystallization. During the sublimation process, the silicon carbide powder decomposes and sublimates to mainly form three main gas phase components: Si, Si2C and SiC2. Since the partial pressure of the Si component is higher than that of the two carbon-containing gas phase components Si2C and SiC2, the gas phase material in the sublimation growth process is usually rich in Si, which makes the unevaporated silicon carbide powder become more and more C-rich, resulting in carbonization of the powder during the growth process. Carbonized solid carbon particles are transported to the growth surface, and carbon inclusions will form in the silicon carbide crystal, resulting in the generation of microscopic defects. In addition, when the silicon flow rate on the surface of the seed crystal is low in the late stage of growth, carbonization will occur on the growth surface; changes in the gas phase composition on the surface of the seed crystal will also lead to the generation of microscopic defects. Therefore, it can be seen that in the PVT method, since silicon evaporates preferentially over carbon, the silicon carbide source in the crucible will change from a silicon-rich ratio to a carbon-rich ratio. The deviation of the non-stoichiometric silicon carbide composition is the main reason for the termination of crystal growth. Solving the problem of the decline in crystal quality caused by the change of the silicon carbide source from a silicon-rich ratio to a carbon-rich ratio is also an urgent problem that we need to solve.

[0006] At the same time, as the crystal size increases, the crucible diameter continues to increase. Due to the skin effect of medium-frequency induction heating, the heating area is located on the crucible wall, and the radial temperature gradient from the crucible wall to the crucible center will increase with the increase of the crucible diameter. The uneven radial heat transfer of the crucible is likely to lead to uneven thermal field distribution, which in turn causes uneven distribution of gas phase components, resulting in different concentrations of components on the radial distribution of the seed crystal surface, which is not conducive to the preparation of high-quality large-size silicon carbide crystals. Summary of the invention

[0007] The purpose of the present invention is to provide a novel silicon carbide preparation device and process in order to achieve the purpose of preparing large-sized, high-quality silicon carbide crystals by physical vapor deposition method in view of the above-mentioned technical problems.

[0008] In view of this, the present invention provides a novel silicon carbide preparation device, comprising:

[0009] an inner crucible, in which silicon carbide powder raw material is arranged;

[0010] An outer guide tube, which is arranged on the upper part of the inner crucible, and the outer guide tube is connected with the inner crucible;

[0011] An inner flow guide tube, which is located inside the outer flow guide tube, silicon powder is arranged between the inner flow guide tube and the outer flow guide tube, the inner flow guide tube is suspended above the inner crucible, an annular gap is formed between the inner flow guide tube and the outer flow guide tube, and the inner flow guide tube is connected to the inner crucible;

[0012] A growth crucible, which is located outside the inner crucible and the outer guide tube, and the growth crucible is connected to the upper part of the outer guide tube;

[0013] A growth base, which is located between the inner crucible and the growth crucible, a seed crystal is arranged on the growth base, and the growth base is installed at the bottom of the growth crucible;

[0014] The carrier gas enters through the air inlet channel extending into the inner crucible, drives the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible to rise, and then is divided into two parts, a mainstream gas phase and a branch gas phase, by the inner guide tube and the outer guide tube. The mainstream gas phase rises and enters the inner guide tube, and the branch gas phase rises and enters between the outer guide tube and the inner guide tube. After the branch gas phase is mixed with the gas phase generated by the silicon carbide powder, it is mixed with the mainstream gas phase to form a mixed gas phase, and then the mixed gas phase enters the cavity between the growth crucible and the outer guide tube. The gas phase generated by sublimation driven by the carrier gas is deposited on the seed crystal, and the remaining gas is discharged through the exhaust channel located at the bottom of the growth crucible.

[0015] Furthermore, the outer guide tube includes:

[0016] A lower guide tube, which is a trumpet-shaped structure with a large diameter at the upper end and a small diameter at the lower end, and the lower end of the lower guide tube is connected to the upper part of the inner crucible;

[0017] The middle guide tube is a circular cylindrical structure, and the middle guide tube is connected to the upper end of the lower guide tube;

[0018] An upper guide tube, which is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end, and the upper guide tube is connected to the upper end of the middle guide tube;

[0019] The lower guide tube, the middle guide tube and the upper guide tube are arranged and connected in sequence from bottom to top, and the lower guide tube, the middle guide tube and the upper guide tube are coaxially arranged.

[0020] Furthermore, a gas outlet is provided on the upper guide tube, and the mixed gas phase enters the space between the outer guide tube and the growth crucible through the gas outlet.

[0021] Furthermore, the inner guide tube includes:

[0022] The first guide tube is a trumpet-shaped structure with a large diameter at the lower end and a small diameter at the upper end;

[0023] The second guide tube is a circular cylindrical structure;

[0024] The third guide tube is a trumpet-shaped structure with a small diameter at the lower end and a large diameter at the upper end;

[0025] The first flow guide tube, the second flow guide tube and the third flow guide tube are arranged and connected in sequence from bottom to top, and the first flow guide tube, the second flow guide tube and the third flow guide tube are coaxially arranged.

[0026] Furthermore, a silicon powder containing ring is provided between the inner guide tube and the outer guide tube, and the silicon powder containing ring comprises:

[0027] The outer shell is an annular structure arranged around the outer periphery of the inner guide tube. The interior of the outer shell is hollow to form a chamber for loading silicon powder. A plurality of through holes are arranged on the outer shell so that the gas phase silicon component formed by the silicon powder loaded in the outer shell after being heated can pass through.

[0028] Furthermore, the silicon powder containing ring further comprises: a silicon powder containing tube,

[0029] The silicon powder containing tube is a tubular structure spirally arranged in the outer shell, the silicon powder is filled in the silicon powder containing tube, and a plurality of through holes are arranged on the tube wall of the silicon powder containing tube, so that the gas phase components formed by the silicon powder loaded in the outer shell after being heated can pass through;

[0030] Alternatively, the silicon powder containing tube is a tubular structure arranged in an annular interval inside the outer shell, the silicon powder is filled in the silicon powder containing tube, and the tube wall of the silicon powder containing tube is a mesh structure, so that the gas phase silicon component formed after the silicon powder loaded in the outer shell is heated can pass through.

[0031] Further, the growth crucible comprises:

[0032] The cylindrical portion is a circular cylindrical structure with a hollow interior, and the cylindrical portion is coaxially arranged with the outer guide cylinder;

[0033] The conical cylinder part is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end. The conical cylinder part is located on the upper side of the cylindrical part and is coaxially arranged and connected to the cylindrical part.

[0034] An outer cover, which covers the upper end of the cone portion;

[0035] A bottom plate is arranged at the lower side of the cylindrical portion, and a plurality of the growth bases are arranged on the bottom plate, and the plurality of the growth bases are evenly spaced and arranged around the inner crucible in a circumferential direction.

[0036] Furthermore, the silicon carbide preparation device also includes:

[0037] A driving device is connected to the inner guide cylinder and is used to drive the inner guide cylinder to move in an up-down direction and / or to rotate in a circumferential direction.

[0038] Furthermore, the driving device comprises:

[0039] A driving motor connected to the upper end of the transmission rod, and used to drive the transmission rod to move in the up-down direction and / or to rotate in the circumferential direction;

[0040] A transmission rod extending into the inner guide tube along a vertical direction, and the transmission rod and the inner guide tube are coaxially arranged;

[0041] A plurality of umbrella-shaped fins are arranged at intervals along the circumferential direction at the lower end of the transmission rod, and the umbrella-shaped fins are sheet-shaped right-angled triangle structures arranged along the vertical direction;

[0042] A clamping ring, which surrounds the outer periphery of the plurality of umbrella-shaped fins and is connected to the umbrella-shaped fins. Correspondingly, a receiving groove is provided on the inner wall of the inner guide tube, and the clamping ring is clamped in the receiving groove;

[0043] When the driving motor drives the transmission rod and the umbrella-shaped fins to move in the up-down direction and / or to rotate in the circumferential direction, the clamping ring can drive the inner guide cylinder to move synchronously.

[0044] A novel silicon carbide preparation process is provided, wherein the silicon carbide preparation process is carried out using the above-mentioned silicon carbide preparation device.

[0045] The beneficial effects of the present invention are:

[0046] In the silicon carbide preparation device described in the present invention, the internal space of the growth crucible is divided into a first space located inside the inner crucible and the outer guide tube and a second space located between the outer guide tube and the growth crucible by an inner crucible and an outer guide tube. In this way, during the preparation process of silicon carbide, the first space located inside and the second space located outside can each maintain a relatively uniform temperature field, avoiding the problem of uneven radial temperature field distribution caused by using a large-sized silicon carbide preparation device, reducing defects, and improving the quality of silicon carbide crystals; more importantly, since the silicon carbide powder raw material in the present invention is mainly sublimated in the first space, and then diffused to the second space and deposited on the seed crystal, the gas phase component is less affected by the uneven radial temperature field distribution, and the long-distance diffusion effect makes the gas phase component entering the second space evenly distributed, and the formed silicon carbide crystal has a small radial component difference, which is conducive to the preparation of large-sized, high-quality silicon carbide crystals. Furthermore, due to the skin effect of the heating device, the side wall temperature of the growth crucible is relatively high, which can effectively prevent the deposition of silicon carbide on the side wall of the growth crucible.

[0047] In addition, in the silicon carbide preparation device described in the present invention, through the arrangement of the inner guide tube and the outer guide tube, the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible can be divided into a mainstream gas phase and a branch gas phase. The branch gas phase flows through the silicon powder holding area, mixes with the gas phase generated by the silicon powder sublimation, and then mixes with the mainstream gas phase to form a mixed gas phase. In this way, the silicon component in the gas phase can be replenished in time during the preparation process of silicon carbide crystals, so that the gas phase components can remain stable for a long time, thereby overcoming the adverse effects caused by the deviation of the silicon carbide components. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a front view structural schematic diagram of the silicon carbide preparation device described in Example 1 of the present invention;

[0049] Figure 2 is a schematic diagram of the three-dimensional structure of the silicon carbide preparation device described in Example 1 of the present invention;

[0050] Figure 3 is a schematic diagram of the cross-sectional structure in the vertical direction of the silicon carbide preparation device described in Example 1 of the present invention;

[0051] Figure 4 It is a schematic diagram of the cross-sectional structure in the vertical direction of the inner guide tube and the silicon powder containing ring in the silicon carbide preparation device described in Example 1 of the present invention;

[0052] Figure 5 is another schematic cross-sectional structure diagram of the silicon carbide preparation device described in Example 1 of the present invention in the vertical direction;

[0053] Figure 6 is a front view structural schematic diagram of the silicon carbide preparation device described in Example 2 of the present invention;

[0054] Figure 7 is a schematic diagram of the three-dimensional structure of the silicon carbide preparation device described in Example 2 of the present invention;

[0055] Figure 8 is a schematic diagram of the cross-sectional structure in the vertical direction of the silicon carbide preparation device described in Example 2 of the present invention;

[0056] Fig. 9 It is a three-dimensional schematic diagram of the cross-sectional structure in the vertical direction of the silicon carbide preparation device described in Example 2 of the present invention.

[0057] The symbols in the figure are:

[0058] 1. Growth crucible; 101. Cylinder; 102. Cone; 103. Outer cover; 104. Bottom plate; 2. Inner crucible; 3. Outer guide tube; 301. Lower guide tube; 302. Middle guide tube; 303. Upper guide tube; 304. Inner cover; 305. Air outlet; 4. Inner guide tube; 401. First guide tube; 402. Second guide tube; 403. Third guide tube; 404. Groove; 5. Silicon powder containing ring; 501. Outer shell; 502. Silicon powder containing tube; 6. Air inlet channel; 601. Air inlet hole; 7. Exhaust channel; 8. Growth base; 9. Driving device; 901. Driving motor; 902. Transmission rod; 903. Umbrella-shaped fin; 904. Snap ring; 10. Guide device; 1001. Guide lining; 1002. Growth chamber; 11. Heating device. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0060] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0062] It should be noted that, in the description of the present application, the orientation or positional relationship indicated by terms such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise stated, these orientation words do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application; the orientation words "inside and outside" refer to the inside and outside relative to the contour of each component itself.

[0063] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0064] Example 1

[0065] like Figures 1 to 5 As shown, a novel silicon carbide preparation device comprises:

[0066] An inner crucible 2, in which silicon carbide powder raw material is arranged;

[0067] An outer guide tube 3, which is arranged on the upper part of the inner crucible 2, and the outer guide tube 3 is connected to the inner crucible 2;

[0068] An inner flow guide tube 4 is located inside the outer flow guide tube 3, silicon powder is arranged between the inner flow guide tube 4 and the outer flow guide tube 3, the inner flow guide tube 4 is suspended above the inner crucible 2, an annular gap is formed between the inner flow guide tube 4 and the outer flow guide tube 3, and the inner flow guide tube 4 is connected to the inner crucible 2;

[0069] A growth crucible 1, which is located outside the inner crucible 2 and the outer guide tube 3, and the growth crucible 1 is connected to the upper part of the outer guide tube 3;

[0070] A growth base 8, which is located between the inner crucible 2 and the growth crucible 1, on which a seed crystal is arranged, and the growth base 8 is installed at the bottom of the growth crucible 1;

[0071] The carrier gas enters through the air inlet channel 6 extending into the inner crucible 2, drives the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible 2 to rise, and then is divided into a mainstream gas phase and a branch gas phase by the inner guide tube 4 and the outer guide tube 3. The mainstream gas phase rises and enters the inner guide tube 4, and the branch gas phase rises and enters between the outer guide tube 3 and the inner guide tube 4. After the branch gas phase is mixed with the gas phase generated by the silicon carbide powder, it is mixed with the mainstream gas phase to form a mixed gas phase, and then the mixed gas phase enters the cavity between the growth crucible 1 and the outer guide tube 3. The gas phase generated by sublimation driven by the carrier gas is deposited on the seed crystal, and the remaining gas is discharged through the exhaust channel 7 located at the bottom of the growth crucible 1.

[0072] In the silicon carbide preparation device described in the present invention, the internal space of the growth crucible 1 is divided into a first space located inside the inner crucible 2 and the outer guide tube 3 and a second space located between the outer guide tube 3 and the growth crucible 1 by the inner crucible 2 and the outer guide tube 3. In this way, during the preparation process of silicon carbide, the first space located on the inner side and the second space located on the outer side can each maintain a relatively uniform temperature field, thereby avoiding the problem of uneven radial temperature field distribution caused by using a large-sized silicon carbide preparation device, reducing the generation of defects, and improving the quality of silicon carbide crystals; more importantly, since the silicon carbide powder raw material in the present invention is mainly sublimated in the first space, and then diffused to the second space and deposited on the seed crystal, the gas phase components are less affected by the uneven radial temperature field distribution. In addition, due to the long-distance diffusion effect, the gas phase components entering the second space are evenly distributed, and the formed silicon carbide crystals have smaller radial component differences, which is conducive to the preparation of large-sized, high-quality silicon carbide crystals. Furthermore, due to the skin effect of the heating device 11 , the temperature of the side wall of the growth crucible 1 is relatively high, which can effectively prevent the deposition of silicon carbide on the side wall of the growth crucible 1 .

[0073] In addition, in the silicon carbide preparation device described in the present invention, through the arrangement of the inner guide tube 4 and the outer guide tube 3, the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible 2 can be divided into a mainstream gas phase and a branch gas phase. The branch gas phase flows through the silicon powder containing area, mixes with the gas phase generated by the silicon powder sublimation, and then mixes with the mainstream gas phase to form a mixed gas phase. In this way, the silicon component in the gas phase can be replenished in time during the preparation process of silicon carbide crystals, so that the gas phase components can remain stable for a long time, thereby overcoming the adverse effects caused by the deviation of the silicon carbide components.

[0074] As some embodiments of the present invention, the inner guide tube 4 can be slidably fixed on the outer guide tube 3 or the inner cover 304 by a connecting rod, etc., so that the inner guide tube 4 is suspended above the inner crucible 2.

[0075] Furthermore, the outer guide tube 3 includes:

[0076] A lower guide tube 301 is a trumpet-shaped structure with a large diameter at the upper end and a small diameter at the lower end, and the lower end of the lower guide tube 301 is connected to the upper part of the inner crucible 2;

[0077] The middle guide tube 302 is a circular cylindrical structure, and the middle guide tube 302 is connected to the upper end of the lower guide tube 301;

[0078] An upper guide tube 303 is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end, and the upper guide tube 303 is connected to the upper end of the middle guide tube 302;

[0079] The lower guide tube 301 , the middle guide tube 302 and the upper guide tube 303 are arranged and connected in sequence from bottom to top, and the lower guide tube 301 , the middle guide tube 302 and the upper guide tube 303 are coaxially arranged, that is, the central axes of the three are straight lines in the same vertical direction.

[0080] Preferably, the height ratio of the lower guide tube 301, the middle guide tube 302 and the upper guide tube 303 is: (0.3-0.6):1:(0.3-0.6).

[0081] Furthermore, the inner diameter d1 of the lower end of the lower guide tube 301 is the same as the inner diameter of the inner crucible 2, and the inner diameter d2 of the upper end of the lower guide tube 301 is (1.3-1.5)*d1; the inner diameter d2 of the upper end of the lower guide tube 301 is the same as the inner diameter of the middle guide tube 302, the inner diameter d3 of the upper end of the upper guide tube 303 is (0.8-1.2)*d1, and the inner diameter d4 of the lower end of the upper guide tube 303 is d2.

[0082] Preferably, the inner diameter d3 of the upper end of the upper guide tube 303 is equal to d1, and the height of the upper guide tube 303 is equal to the height of the lower guide tube 301.

[0083] Furthermore, the outer guide tube 3 further includes an inner cover 304 , and the inner cover 304 covers the upper end of the outer guide tube 3 .

[0084] Furthermore, a gas outlet 305 is provided on the upper guide tube 303 , and the mixed gas phase enters the space between the outer guide tube 3 and the growth crucible 1 through the gas outlet 305 .

[0085] As some embodiments of the present invention, a plurality of air outlet holes 305 spaced apart along the circumferential direction are provided on the upper portion of the upper guide tube 303 .

[0086] Furthermore, the inner guide tube 4 includes:

[0087] The first guide tube 401 is a trumpet-shaped structure with a large diameter at the lower end and a small diameter at the upper end;

[0088] The second guide tube 402 is a circular cylindrical structure;

[0089] The third guide tube 403 is a trumpet-shaped structure with a small diameter at the lower end and a large diameter at the upper end;

[0090] The first flow guide tube 401 , the second flow guide tube 402 and the third flow guide tube 403 are sequentially arranged and connected from bottom to top, and the first flow guide tube 401 , the second flow guide tube 402 and the third flow guide tube 403 are coaxially arranged.

[0091] Preferably, the height ratio of the first flow guide tube 401, the second flow guide tube 402 and the third flow guide tube 403 is: (0.2-0.4):1:(0.2-0.4).

[0092] Furthermore, the inner diameter of the lower end of the first guide tube 401 is recorded as d5, then d1<d5<d2, preferably, d5=0.5*(d1+d2); the inner diameter of the upper end of the first guide tube 401 is recorded as d6, then d6=(0.6~0.8)*d1; the inner diameter of the second guide tube 402 is equal to d6; the inner diameter of the lower end of the third guide tube 403 is recorded as d7, then d7=d6, and the inner diameter of the upper end of the third guide tube 403 is recorded as d8, then d1<d8<d2, preferably, d8=0.5*(d1+d2).

[0093] Preferably, the first guide tube 401 and the third guide tube 403 have the same height.

[0094] Furthermore, the total height of the inner guide tube 4 is 0.7 to 0.8 times the total height of the outer guide tube 3 .

[0095] As some embodiments of the present invention, when preparing silicon carbide, the size and relative distance between the inner guide tube 4 and the outer guide tube 3 can be adjusted as needed, thereby adjusting the ratio of the mainstream gas phase and the branch gas phase to make it suitable for different working conditions.

[0096] Furthermore, a silicon powder containing ring 5 is arranged between the inner guide tube 4 and the outer guide tube 3 . The silicon powder containing ring 5 is an annular structure with through holes arranged on the surface. The silicon powder is arranged in the silicon powder containing ring 5 .

[0097] Specifically, the silicon powder containing ring 5 comprises:

[0098] The outer shell 501 is an annular structure arranged around the outer periphery of the inner guide tube 4. The interior of the outer shell 501 is hollow to form a chamber for loading silicon powder. A plurality of through holes are arranged on the outer shell 501 so that the gas phase silicon component formed after the silicon powder loaded in the outer shell 501 is heated can pass through and mix with the branch gas phase generated by sublimation, so as to supplement the silicon carbide powder raw material and the gas phase silicon component in the reaction space, reduce the carbonization of the silicon carbide powder raw material, and at the same time maintain the concentration of carbon and silicon components in the gas phase components in the reaction space to meet the process requirements, reduce impurity defects in the crystal, and thus improve the quality of crystal growth.

[0099] As some embodiments of the present invention, the silicon powder containing ring 5 further includes:

[0100] The silicon powder containing tube 502 is a tubular structure spirally arranged in the outer shell 501. The silicon powder is filled in the silicon powder containing tube 502. A plurality of through holes are arranged on the tube wall of the silicon powder containing tube 502 so that the gas phase components formed by the silicon powder loaded in the outer shell 501 after being heated can pass through.

[0101] As some embodiments of the present invention, the silicon powder containing ring 5 further includes:

[0102] A plurality of silicon powder containing tubes 502 are tubular structures arranged in annular intervals in the outer shell 501. The silicon powder is filled in the silicon powder containing tubes 502. The tube wall of the silicon powder containing tubes 502 is a mesh structure, so that the gas phase silicon component formed by the silicon powder loaded in the outer shell 501 after being heated can pass through.

[0103] Preferably, the outer guide tube 3, the inner guide tube 4 and the silicon powder containing ring 5 are made of high temperature resistant materials.

[0104] Furthermore, the growth crucible 1 comprises:

[0105] The cylindrical portion 101 is a circular cylindrical structure with a hollow interior, and the cylindrical portion 101 is coaxially arranged with the outer guide cylinder 3;

[0106] The conical cylinder portion 102 is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end. The conical cylinder portion 102 is located on the upper side of the cylindrical portion 101 and is coaxially arranged and connected to the cylindrical portion 101;

[0107] An outer cover 103, which covers the upper end of the cone portion 102;

[0108] A bottom plate 104 is disposed on the lower side of the cylindrical portion 101, and a plurality of the growth bases 8 are disposed on the bottom plate 104, and the plurality of the growth bases 8 are evenly spaced and arranged around the inner crucible 2 in a circumferential direction;

[0109] A closed space is formed by the cylindrical portion 101 , the conical portion 102 , the outer cover 103 and the bottom plate 104 .

[0110] Preferably, the side wall of the cone portion 102 is arranged parallel to the upper guide tube 303 .

[0111] In the silicon carbide preparation device described in the present invention, an annular inlet located between the lower guide tube 301 and the first guide tube 401 and a circular inlet located in the first guide tube are formed above the inner crucible 2 through the lower guide tube 301 and the first guide tube 401. The carrier gas enters through the air inlet channel 6 extending into the inner crucible 2, drives the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible 2 to rise, and part of it enters the first subspace in the inner guide tube 4 through the circular inlet to form the mainstream gas phase; the other part enters the second subspace between the inner guide tube 4 and the outer guide tube 3 through the annular inlet to form the branch gas phase, and then drives the gas phase generated by the silicon carbide powder sublimation to rise through the branch gas phase, and then mixes with the mainstream gas phase to form a mixed gas phase, so as to supplement the silicon component in the gas phase component; in addition, as Figure 5As shown, since the second subspace between the inner guide tube 4 and the outer guide tube 3 is in a shape with small ends and large in the middle, after the gas enters the second subspace, the flow rate becomes smaller, and the silicon powder in the second subspace can be fully contacted and heated. At the same time, due to the obstruction and guiding effect of the silicon powder containing ring 5, the branch gas phase can form an airflow flowing in a clockwise or counterclockwise direction around the silicon powder containing ring 5, further promoting the sublimation of the gas phase silicon in the silicon powder containing ring 5 and its mixing with the branch gas phase. After entering the upper part of the second subspace, due to the contraction effect of the third guide tube 403 and the upper guide tube 303, the gas phase pressure in the upper part of the second subspace increases, the flow rate increases, and it can be quickly discharged, forming an annular airflow around the third guide tube 403, and the Bernoulli principle of the annular airflow accelerates the mainstream gas phase inside the third guide tube 403, thereby promoting the discharge of the gas phase in the inner guide tube 4; after the branch gas phase is mixed with the gas phase generated by the silicon powder sublimation, it is then discharged in the third guide tube. The upper space of the tube 403 is mixed with the mainstream gas phase to form a mixed gas phase, which enters the second space between the growth crucible 1 and the outer guide tube 3. In the second space, through the structural shape coordination of the growth crucible 1, the outer guide tube 3 and the inner crucible 2, a uniform diffusion zone with uniform cross-sectional area can be formed in the upper part of the second space (i.e., the area between the middle guide tube 302, the upper guide tube 303 and the growth crucible 1), a deceleration zone with a gradually increasing cross-sectional area from top to bottom (i.e., the area between the lower guide tube 301 and the growth crucible 1) is formed in the middle of the second space, and a uniform sedimentation zone with uniform cross-sectional area is formed in the lower part of the second space. In this way, when the mixed gas phase passes through the second space, its flow velocity will experience a change process of first high-speed uniform speed, then deceleration, and then low-speed uniform speed. The structural shape setting of the second space can achieve uniform mixing of gas phase components and slowing down of deposition rate, which is beneficial to improving the uniformity of silicon carbide crystals and reducing the generation of defects.

[0112] Furthermore, a heating device 11 is arranged outside the growth crucible 1 . Preferably, the heating device 11 is an electric heating device.

[0113] Preferably, the heating device 11 is located on the outside of the cylindrical portion 101 , or the cylindrical portion 101 and the conical portion 102 .

[0114] Preferably, the gas inlet channel 6 is inserted into the inner crucible 2 from the bottom of the inner crucible 2, an end cover is provided at the upper end of the gas inlet channel 6, and a plurality of gas inlet holes 601 are provided on the end cover, so that the carrier gas can enter the inner crucible 2 through the gas inlet holes 601.

[0115] As some embodiments of the present invention, the silicon powder is a silicon-containing powder, which includes silicon carbide powder and elemental silicon powder. Preferably, in the silicon powder, the weight percentage of the elemental silicon powder is 60-90%.

[0116] Example 2

[0117] like Figures 6 to 9 As shown, a novel silicon carbide preparation device, compared with the silicon carbide preparation device described in the above embodiment 1, further comprises:

[0118] The driving device 9 is connected to the inner guide cylinder 4 and is used to drive the inner guide cylinder 4 to move in the up-down direction and / or to rotate in the circumferential direction.

[0119] Specifically, the driving device 9 includes:

[0120] A driving motor 901 connected to the upper end of the transmission rod 902, and used to drive the transmission rod 902 to move in the up-down direction and / or to rotate in the circumferential direction;

[0121] A transmission rod 902, which extends into the inner guide tube 4 along the vertical direction, and the transmission rod 902 is coaxially arranged with the inner guide tube 4;

[0122] A plurality of umbrella-shaped fins 903 are arranged at intervals along the circumferential direction at the lower end of the transmission rod 902, and the umbrella-shaped fins 903 are sheet-shaped right-angled triangle structures arranged along the vertical direction, one right-angled side of the right-angled triangle structure is parallel to and connected to the transmission rod 902, and the other right-angled side is located on the upper side of the umbrella-shaped fin 903;

[0123] A clamping ring 904, which surrounds the outer periphery of the plurality of umbrella-shaped fins 903 and is connected to the umbrella-shaped fins 903. Correspondingly, a receiving groove 404 is provided on the inner wall of the inner guide tube 4, and the clamping ring 904 is clamped in the receiving groove 404 to achieve connection between the clamping ring 904 and the inner guide tube 4;

[0124] When the driving motor 901 drives the transmission rod 902 and the umbrella-shaped fins 903 to move in the up-down direction and / or to rotate in the circumferential direction, the clamping ring 904 can drive the inner guide tube 4 to move synchronously.

[0125] Preferably, the accommodating groove 404 is located on the inner wall of the second guide tube 402 .

[0126] As some embodiments of the present application, the driving device 9 includes 3 to 6 umbrella-shaped fins 903 .

[0127] It should be noted that the driving device 9 may include one or more driving motors 901, which can specifically drive the transmission rod 902 to move in the up and down directions, and / or, preferably, to rotate in the circumferential direction. The specific structure of the driving motor 901 and the connection method between the driving motor 901 and the transmission rod 902 have been disclosed in many ways in the prior art and will not be repeated here.

[0128] In the driving device 9, a plurality of umbrella-shaped fins 903 are arranged around the lower end of the transmission rod 902, so that an umbrella-like structure can be formed at the lower end of the transmission rod 902. This structure can effectively prevent the sublimated components in the mainstream gas phase from being deposited on the transmission rod 902 while achieving uniform exhaust.

[0129] At the same time, when the driving device 9 drives the inner guide tube 4 to move in the up and down directions, the silicon carbide preparation device can adjust the ratio of the mainstream gas phase and the branch gas phase through the up and down movement of the inner guide tube 4, thereby realizing dynamic adjustment of the composition of the gas phase generated by sublimation.

[0130] In addition, when the driving device 9 drives the inner guide tube 4 to rotate in the circumferential direction, it can drive the gas phase inside the inner guide tube 4 and the gas phase between the inner guide tube 4 and the outer guide tube 3 to rotate clockwise or counterclockwise in the horizontal direction, accelerate the mixing of the gas phases in different radial regions, avoid the deposition of the gas phase on components such as the silicon powder containing ring 5, and make the mixed gas phase entering the outer guide tube 3 and the growth crucible 1 uniform.

[0131] As some embodiments of the present invention, a flow guiding device 10 is provided between the outer flow guiding tube 3 and the growth crucible 1, and the flow guiding device 10 is used to guide the mixed gas phase entering between the outer flow guiding tube 3 and the growth crucible 1, specifically:

[0132] The flow guiding device 10 comprises:

[0133] The guide lining 1001 is an internally hollow annular structure arranged between the outer guide tube 3 and the growth crucible 1. A plurality of concave growth chambers 1002 are arranged in the guide lining 1001. A growth base 8 and a seed crystal are arranged in each growth chamber 1002, and the sublimated gas is deposited on the seed crystal. At the same time, an exhaust hole is arranged on the side wall or bottom wall of the growth chamber 1002, and the exhaust hole is connected to the exhaust channel 7 to discharge the remaining gas through the exhaust hole.

[0134] Furthermore, a plurality of growth chambers 1002 are arranged on the guide device 10 and are spaced apart circumferentially around the outer guide tube 3. The shape of the growth chamber 1002 can be designed as required, such as the growth chamber 1002 can be set to a cylindrical shape.

[0135] Example 3

[0136] A novel method for preparing silicon carbide, the method being used for the novel silicon carbide preparation device described in the above-mentioned embodiment 1 or embodiment 2, the method comprising the steps of:

[0137] S1, determining the size parameters of the silicon carbide preparation device, the mass of the silicon carbide powder raw material, and the mass of the silicon powder between the inner guide tube 4 and the outer guide tube 3 according to the size of the silicon carbide crystal to be prepared, wherein the size parameters at least include: the height of the inner guide tube 4;

[0138] S2, adjusting the inner guide tube 4 to a set height, loading the set silicon carbide powder raw material and silicon powder into the novel silicon carbide preparation device, and installing the seed crystal on the single crystal growth surface;

[0139] S3, raising the temperature to a preset temperature for crystal growth.

[0140] As some embodiments of the present invention, the size parameters in step S1, the mass of the silicon carbide powder raw material and the silicon powder, and the height of the inner guide tube 4 can be determined through experiments.

[0141] Preferably, when the novel silicon carbide preparation device includes a driving device 9, the initial height of the inner guide tube 4 can be first determined in step S1, and then the height of the inner guide tube 4 can be adjusted according to the change of the gas phase composition in the growth crucible 1 during the crystal growth process in step S3 to adjust the ratio of the mainstream gas phase and the branch gas phase.

[0142] In addition, during the crystal growth process, the rotation speed of the inner guide tube 4 can be adjusted according to the composition difference between the mainstream gas phase and the branch gas phase, wherein the rotation speed of the inner guide tube 4 is preferably not more than 20 revolutions / min. The specific value of the rotation speed of the inner guide tube 4 can be determined through experiments. Generally, the greater the composition difference between the mainstream gas phase and the branch gas phase, the greater the rotation speed of the inner guide tube 4.

[0143] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A silicon carbide preparation device, It is characterized in that include: an inner crucible (2) in which a silicon carbide powder raw material is arranged; An outer flow guide tube (3) is arranged on the upper part of the inner crucible (2), and the outer flow guide tube (3) is connected to the inner crucible (2); an inner flow guide tube (4) located inside the outer flow guide tube (3), silicon powder being arranged between the inner flow guide tube (4) and the outer flow guide tube (3), the inner flow guide tube (4) being suspended above the inner crucible (2), forming an annular gap between the inner flow guide tube (4) and the outer flow guide tube (3), and the inner flow guide tube (4) being in communication with the inner crucible (2); A growth crucible (1) located outside the inner crucible (2) and the outer guide tube (3), and the upper parts of the growth crucible (1) and the outer guide tube (3) are connected; A growth base (8) located between the inner crucible (2) and the growth crucible (1), a seed crystal being arranged on the growth base (8), and the growth base (8) being installed at the bottom of the growth crucible (1); The carrier gas enters through the gas inlet channel (6) extending into the inner crucible (2), drives the gas phase generated by the sublimation of the silicon carbide powder raw material in the inner crucible (2) to rise, and is then divided into two parts, a mainstream gas phase and a branch gas phase, by the inner guide tube (4) and the outer guide tube (3). The mainstream gas phase rises and enters the inner guide tube (4), and the branch gas phase rises and enters between the outer guide tube (3) and the inner guide tube (4). The branch gas phase is mixed with the gas phase generated by the sublimation of the silicon powder, and then mixed with the mainstream gas phase to form a mixed gas phase. The mixed gas phase then enters the cavity between the growth crucible (1) and the outer guide tube (3). The gas phase generated by the sublimation driven by the carrier gas is deposited on the seed crystal, and the remaining gas is discharged through the exhaust channel (7) located at the bottom of the growth crucible (1); The outer guide tube (3) comprises: A lower flow guide tube (301) is a trumpet-shaped structure with a large diameter at the upper end and a small diameter at the lower end, and the lower end of the lower flow guide tube (301) is connected to the upper part of the inner crucible (2); A middle flow guide tube (302) is a circular cylindrical structure, and the middle flow guide tube (302) is connected to the upper end of the lower flow guide tube (301); An upper guide tube (303) is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end, and the upper guide tube (303) is connected to the upper end of the middle guide tube (302); The lower flow guide tube (301), the middle flow guide tube (302) and the upper flow guide tube (303) are sequentially arranged and connected from bottom to top, and the lower flow guide tube (301), the middle flow guide tube (302) and the upper flow guide tube (303) are coaxially arranged; The inner guide tube (4) comprises: A first guide tube (401) which is a trumpet-shaped structure with a large diameter at the lower end and a small diameter at the upper end; A second guide tube (402) which is a circular cylindrical structure; A third guide tube (403) is a trumpet-shaped structure with a small diameter at the lower end and a large diameter at the upper end; The first flow guide tube (401), the second flow guide tube (402) and the third flow guide tube (403) are sequentially arranged and connected from bottom to top, and the first flow guide tube (401), the second flow guide tube (402) and the third flow guide tube (403) are coaxially arranged; The growth crucible (1) comprises: A cylindrical portion (101) which is a circular cylindrical structure with a hollow interior, wherein the cylindrical portion (101) is coaxially arranged with the outer guide tube (3); The conical cylinder portion (102) is a trumpet-shaped structure with a small diameter at the upper end and a large diameter at the lower end. The conical cylinder portion (102) is located on the upper side of the cylindrical portion (101) and is coaxially arranged and connected to the cylindrical portion (101); An outer cover (103) covering the upper end of the conical cylinder (102); A bottom plate (104) is arranged on the lower side of the cylindrical portion (101), and a plurality of the growth bases (8) are arranged on the bottom plate (104), and the plurality of the growth bases (8) are evenly spaced and arranged around the inner crucible (2) in a circumferential direction; The silicon carbide preparation device also includes: A driving device (9) is connected to the inner flow guide tube (4) and is used to drive the inner flow guide tube (4) to move in an up-down direction and / or to rotate in a circumferential direction; when the driving device (9) drives the inner flow guide tube (4) to move in an up-down direction, the silicon carbide preparation device can adjust the ratio of the mainstream gas phase and the branch gas phase through the up-down movement of the inner flow guide tube (4).

2. The silicon carbide preparation device according to claim 1, It is characterized in that A gas outlet hole (305) is provided on the upper guide tube (303), and the mixed gas phase enters the space between the outer guide tube (3) and the growth crucible (1) through the gas outlet hole (305).

3. The silicon carbide preparation device according to claim 1, It is characterized in that A silicon powder containing ring (5) is arranged between the inner guide tube (4) and the outer guide tube (3), and the silicon powder containing ring (5) comprises: The outer shell (501) is an annular structure arranged around the outer periphery of the inner guide tube (4); the interior of the outer shell (501) is hollow, forming a chamber for loading silicon powder; a plurality of through holes are arranged on the outer shell (501) so that the gas phase silicon component formed after the silicon powder loaded in the outer shell (501) is heated can pass through.

4. The silicon carbide preparation device according to claim 3, It is characterized in that The silicon powder containing ring (5) further comprises: a silicon powder containing tube (502), The silicon powder containing tube (502) is a tubular structure spirally arranged in the outer shell (501), the silicon powder is filled in the silicon powder containing tube (502), and a plurality of through holes are arranged on the tube wall of the silicon powder containing tube (502) so that the gas phase components formed by the silicon powder loaded in the outer shell (501) after being heated can pass through; Alternatively, the silicon powder containing tube (502) is a tubular structure arranged in an annular interval inside the outer shell (501), the silicon powder is filled in the silicon powder containing tube (502), and the tube wall of the silicon powder containing tube (502) is a mesh structure, so that the gas phase silicon component formed after the silicon powder loaded in the outer shell (501) is heated can pass through.

5. The silicon carbide preparation device according to claim 1, It is characterized in that The driving device (9) comprises: A driving motor (901) connected to the upper end of the transmission rod (902) and used to drive the transmission rod (902) to move in an up-down direction and / or to rotate in a circumferential direction; A transmission rod (902) extending into the inner flow guide cylinder (4) along a vertical direction, and the transmission rod (902) and the inner flow guide cylinder (4) are coaxially arranged; A plurality of umbrella-shaped fins (903) are arranged at intervals along the circumferential direction at the lower end of the transmission rod (902), and the umbrella-shaped fins (903) are sheet-shaped right-angled triangle structures arranged along the vertical direction; a snap ring (904) which surrounds the periphery of the plurality of umbrella-shaped fins (903) and is connected to the umbrella-shaped fins (903); correspondingly, a receiving groove (404) is provided on the inner wall of the inner guide tube (4), and the snap ring (904) is fixed in the receiving groove (404); When the driving motor (901) drives the transmission rod (902) and the umbrella-shaped fin (903) to move in the up-down direction and / or to rotate in the circumferential direction, the clamping ring (904) can drive the inner guide tube (4) to move synchronously.

6. A process for preparing silicon carbide, It is characterized in that The silicon carbide preparation process is carried out using the silicon carbide preparation device described in any one of claims 1 to 5.

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