Silicon carbide crystal growth apparatus

Abstract

This invention discloses a silicon carbide crystal growth apparatus, comprising: a crucible body having an open-top cavity; a crucible cover disposed at the open end of the crucible body, with a seed crystal adhered to its inner side; a flow guide disposed within the cavity, comprising a support rod and flow guide blades, the support rod being vertically oriented, the flow guide blades surrounding the support rod, the flow guide blades and support rod defining a spiral airflow channel; and a graphite filter plate disposed within the spiral airflow channel, the graphite filter plate being connected between adjacent layers of the spiral airflow channel, the graphite filter plate having multiple filter holes, each filter hole penetrating the graphite filter plate in the thickness direction, and multiple graphite filter plates arranged in layers along the axial direction of the spiral airflow channel. The silicon carbide crystal growth apparatus according to this invention can reduce defects such as microtubes, which is beneficial for improving the quality of silicon carbide crystals.

Description

Technical Field

[0001] This invention relates to the field of crystal preparation technology, and in particular to a silicon carbide crystal growth apparatus. Background Technology

[0002] The semiconductor industry has developed through three stages. The third generation of semiconductor materials, represented by silicon carbide, has the characteristics of high breakdown electric field, high saturated electron mobility and high thermal conductivity compared with the first two generations of products. It has shown great advantages in high voltage and high frequency fields and has been widely praised in the industry. Moreover, it has great application potential in electronics, printing, communications, detection and environmental protection.

[0003] In related technologies, the gas phase in silicon carbide crystal growth devices cannot be effectively controlled during the crystal growth process, which easily leads to defects such as microtubes and results in poor crystal quality. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a silicon carbide crystal growth apparatus that can reduce defects such as microtubes, thereby improving the quality of silicon carbide crystals.

[0005] A silicon carbide crystal growth apparatus according to an embodiment of the present invention includes: a crucible body having a top-open receiving cavity, the bottom of which is filled with silicon carbide raw material; a crucible cover disposed at the opening of the crucible body, the inner side of which is attached a seed crystal; and a flow guide disposed within the receiving cavity, the flow guide including a support rod and flow guide blades, the support rod being vertically arranged, the flow guide blades being arranged around the support rod and spirally extending along the axial direction of the support rod, the radial inner wall of the flow guide blades being flush with the support rod. The radial outer wall of the rod is connected, and the guide vanes and the support rod define a spiral airflow channel; a graphite filter plate is disposed in the spiral airflow channel, and the graphite filter plate is connected between two adjacent layers of the spiral airflow channel, and the radial inner side of the graphite filter plate is connected to the radial outer side of the support rod. The graphite filter plate has multiple filter holes, each filter hole penetrating the graphite filter plate in the thickness direction. There are multiple graphite filter plates, and the multiple graphite filter plates are arranged in layers along the axial direction of the spiral airflow channel.

[0006] According to an embodiment of the present invention, a silicon carbide crystal growth apparatus is provided on a flow guide with multiple graphite filter plates arranged in layers along the axial direction of a spiral airflow channel. As the silicon carbide atmosphere rises along the spiral airflow channel, the multiple graphite filter plates can react with the silicon-rich atmosphere flowing through them layer by layer and in multiple gradients. This helps to eliminate or slow down the corrosiveness of the silicon carbide atmosphere, thereby helping to suppress defects such as microtubes caused by silicon droplets and polymorphs. At the same time, the graphite filter plates can filter particulate impurities such as carbon impurities floating in the silicon carbide atmosphere layer by layer and in multiple gradients, which helps to reduce defects such as microtubes caused by carbon encapsulation on the single crystal surface, thereby improving the growth quality of silicon carbide crystals.

[0007] In some embodiments of the present invention, in the axial direction of the support rod, two adjacent layers of graphite filter plates are respectively located on the radial sides of the support rod.

[0008] In some embodiments of the present invention, the pore sizes of a plurality of filter holes located on the same graphite filter plate are equal, and in the direction from bottom to top, the parameters of the upper graphite filter plate are smaller than the parameters of the lower graphite filter plate, wherein the parameters are at least one of pore size, porosity and thickness.

[0009] In some embodiments of the present invention, a plane passing through the central axis of the support rod is used as a reference plane. The radial inner edge of the guide vane located on the same layer on the reference plane is higher than the radial outer edge of the guide vane, and the angle between the lower surface of the guide vane located on the same layer and the horizontal plane is α, where α satisfies: 30°≤α≤60°.

[0010] In some embodiments of the present invention, the inner peripheral wall of the crucible body is provided with a spiral groove, the spiral groove is matched with the shape of the guide vane, the outer edge of the guide vane is engaged with the spiral groove, and / or, the bottom wall of the crucible body is provided with a fixing groove, and the bottom end of the support rod is engaged with the fixing groove.

[0011] In some embodiments of the present invention, the silicon carbide crystal growth apparatus further includes: a driving device, the driving device being disposed below the crucible body, the bottom of the support rod passing through the crucible body and connected to the driving device, and the driving device being adapted to drive the flow guide to rotate at different speeds.

[0012] In some embodiments of the present invention, the silicon carbide crystal growth apparatus further includes: a first flow guide shroud, the first flow guide shroud being disposed on the outside of the flow guide member, the bottom of the first flow guide shroud having a first opening facing the silicon carbide raw material, and the top of the first flow guide shroud having a second opening facing the seed crystal, wherein the outer diameter of the flow guide blade and the inner diameter of the first flow guide shroud gradually decrease in the direction from bottom to top.

[0013] In some embodiments of the present invention, the first flow guide shroud is provided with a plurality of flow guide holes, the flow guide holes penetrating the first flow guide shroud in the thickness direction of the first flow guide shroud, and the silicon carbide crystal growth apparatus further includes: a second flow guide shroud, the second flow guide shroud being disposed on the outside of the first flow guide shroud, and the inner wall of the second flow guide shroud being spaced apart from the outer wall of the first flow guide shroud, and the top of the second flow guide shroud having a third opening directly opposite the seed crystal and the second opening.

[0014] In some embodiments of the present invention, the silicon carbide crystal growth apparatus further includes: a third flow guide shroud disposed within the receiving cavity, the third flow guide shroud defining a first chamber, a second chamber, and a third chamber arranged sequentially from bottom to top. In the direction from bottom to top, the flow area of ​​the first chamber gradually decreases, the flow area of ​​the second chamber first decreases and then increases, and the flow area of ​​the third chamber gradually increases. The flow guide blade includes a first helical segment, a second helical segment, and a third helical segment connected sequentially from bottom to top. The first helical segment, the second helical segment, and the third helical segment are respectively disposed within the first chamber, the second chamber, and the third chamber. In the direction from bottom to top, the outer diameter of the first helical segment gradually decreases, the outer diameter of the second helical segment first decreases and then increases, and the outer diameter of the third helical segment gradually increases.

[0015] In some embodiments of the present invention, the silicon carbide crystal growth apparatus further includes: a shielding cover, the shielding cover being connected to the third flow guide cover and the shielding cover being located at the open opening at the top of the third chamber, the shielding cover having a flow guide channel at its center, the flow guide channel being coaxially arranged with the third chamber, and the shielding cover also having a plurality of through holes for filtering the airflow.

[0016] In some embodiments of the present invention, the driving device includes a first motor, a second motor, and a third motor, and the support rod includes a first support rod, a second support rod, and a third support rod. The first motor is connected to the first helical segment through the first support rod, the second motor is connected to the second helical segment through the second support rod, and the third motor is connected to the third helical segment through the third support rod. The central axes of the first support rod, the second support rod, and the third support rod are on the same straight line. The first support rod is arranged around the second support rod and is rotatably engaged with the second support rod, and the second support rod is arranged around the third support rod and is rotatably engaged with the third support rod.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is a partial explosion diagram of the silicon carbide crystal growth apparatus according to Embodiment 1 of the present invention;

[0019] Figure 2 This is a schematic diagram of the flow guide and graphite filter plate according to Embodiment 1 of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the crucible body, crucible lid, quartz cover, heat insulation felt and induction coil according to Embodiment 2 of the present invention;

[0021] Figure 4 This is a partial structural schematic diagram of the silicon carbide crystal growth apparatus according to Embodiment 3 of the present invention;

[0022] Figure 5 This is a partial structural schematic diagram of the silicon carbide crystal growth apparatus according to Embodiment 4 of the present invention;

[0023] Figure 6 This is a partial structural schematic diagram of the silicon carbide crystal growth apparatus according to Embodiment 5 of the present invention;

[0024] Figure 7 This is a schematic diagram of the silicon carbide crystal growth apparatus according to Embodiment Six of the present invention.

[0025] Figure label:

[0026] Silicon carbide crystal growth apparatus 100;

[0027] 10 crucible body; 11 spiral groove; 12 fixing groove; 13 receiving cavity;

[0028] 20; crucible lid; 21;

[0029] Flow guide 30; support rod 31; first support rod 311; second support rod 312; third support rod 313; flow guide vane 32; first spiral section 321; second spiral section 322; third spiral section 323; radial inner wall 32a; radial outer wall 32b; spiral airflow channel 33;

[0030] Graphite filter plate 40; filter hole 41; first graphite filter plate 4a; second graphite filter plate 4b; third graphite filter plate 4c.

[0031] Drive unit 50; first motor 51; first transmission element 511; second motor 52; second transmission element 521; third motor 53; third transmission element 531;

[0032] First air guide 60; First opening 61; Second opening 62; Air guide hole 63;

[0033] Second fairing 70; Third opening 71;

[0034] Third flow guide shroud 80; First chamber 81; Second chamber 82; Third chamber 83; Shielding cover 84; Flow guide channel 841; Through hole 842;

[0035] Quartz cover 91; thermal insulation felt 92; induction coil 93;

[0036] Silicon carbide raw material 200. Detailed Implementation

[0037] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0038] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0039] The following is for reference. Figures 1-7 A silicon carbide crystal growth apparatus 100 according to an embodiment of the present invention is described.

[0040] Reference Figure 1 As shown, the silicon carbide crystal growth apparatus 100 according to an embodiment of the present invention includes: a crucible body 10, a crucible cover 20, a flow guide 30, and a graphite filter plate 40.

[0041] Reference Figure 1 As shown, the crucible body 10 has a top-open receiving cavity 13, at the bottom of which silicon carbide raw material 200 is placed. A crucible lid 20 is located at the opening of the crucible body 10, and a seed crystal 21 is attached to the inner side of the lid 20. For example, referring to… Figure 1 As shown, the crucible body 10 is detachably connected to the crucible cover 20. The silicon carbide raw material 200 is placed at the bottom of the receiving cavity 13. The seed crystal 21 is attached to the lower surface of the crucible cover 20. After being heated and sublimated, the silicon carbide raw material 200 flows to the seed crystal 21 to be deposited and grown on the seed crystal 21.

[0042] Reference Figure 1 and Figure 2 As shown, the flow guide 30 is disposed within the receiving cavity 13. For example, the flow guide 30 can be fixedly or rotatably disposed within the receiving cavity 13. The flow guide 30 includes a support rod 31 and a flow guide vane 32. The support rod 31 is vertically arranged (see reference). Figure 1 In the vertical direction, the guide vane 32 is arranged around the support rod 31, and the guide vane 32 extends spirally along the axial direction of the support rod 31. The radial inner wall 32a of the guide vane 32 is connected to the radial outer wall 32b of the support rod 31. The guide vane 32 and the support rod 31 define a spiral airflow channel 33.

[0043] Reference Figure 1 and Figure 2 As shown, a graphite filter plate 40 is disposed within the spiral airflow channel 33, and the graphite filter plate 40 is connected between two adjacent layers of the spiral airflow channel 33. The radially inner side of the graphite filter plate 40 is connected to the radially outer side of the support rod 31. The graphite filter plate 40 has multiple filter holes 41, each filter hole 41 penetrating the graphite filter plate 40 in the thickness direction. There are multiple graphite filter plates 40, which are arranged in layers along the axial direction of the spiral airflow channel 33. In this application, "multiple" refers to two or more.

[0044] For example, such as Figure 1 As shown, the flow guide 30 is provided with three graphite filter plates 40. The three graphite filter plates 40 are arranged in layers along the vertical direction in the spiral airflow channel 33. The graphite filter plates 40 can be connected to the flow guide 30 by means of pasting, snap-fitting, threaded fasteners, etc.

[0045] It should be noted that the inventors discovered in their actual research that a high temperature of 2100℃-2400℃ is generally required during the growth of silicon carbide single crystals. The silicon carbide raw material 200 decomposes to generate a Si-rich atmosphere. This Si-rich atmosphere is not stable and has a relatively severe corrosive effect on other graphite components. At the same time, the ratio of Si atoms to C atoms in the atmosphere cannot meet the equilibrium ratio for the formation of silicon carbide single crystals, which leads to many problems such as silicon droplets, inclusions, and dislocation defects such as microtubes, resulting in severe phase transitions.

[0046] In the silicon carbide crystal growth apparatus 100 according to an embodiment of the present invention, during operation, the heated and sublimated silicon carbide atmosphere spirals upward along the spiral airflow channel 33 and passes through multiple graphite filter plates 40. It is understood that when the silicon carbide atmosphere passes through the graphite filter plates 40, on the one hand, the graphite filter plates 40 can react with the silicon-rich atmosphere flowing through them, which helps to mitigate the corrosiveness of the silicon carbide atmosphere, thereby helping to suppress defects such as microtubules caused by silicon droplets and polymorphs. On the other hand, the graphite filter plates 40 can filter out carbon impurities and other particles floating in the silicon carbide atmosphere. The ratio of Si atoms to C atoms in the balanced atmosphere helps reduce defects such as microtubes caused by carbon encapsulation on the single crystal surface. At the same time, by arranging multiple graphite filter plates 40 in layers along the axial direction of the spiral airflow channel 33, the multiple graphite filter plates 40 can react with the silicon-rich atmosphere layer by layer and in multiple gradients, and filter particulate impurities such as carbon impurities floating in the silicon carbide atmosphere. This can further reduce the corrosiveness of the silicon carbide atmosphere and improve the filtration effect on particulate impurities, which is conducive to further reducing defects such as microtubes in silicon carbide crystals and improving the growth quality of silicon carbide crystals.

[0047] In view of this, the silicon carbide crystal growth apparatus 100 according to the present invention provides a plurality of graphite filter plates 40 on the flow guide 30, which are arranged in layers along the axial direction of the spiral airflow channel 33. As the silicon carbide atmosphere rises along the spiral airflow channel 33, the plurality of graphite filter plates 40 can react with the silicon-rich atmosphere flowing through them layer by layer and in multiple gradients, which helps to eliminate the corrosiveness of the silicon carbide atmosphere and thus helps to suppress defects such as microtubes caused by silicon droplets and polymorphs. On the other hand, the plurality of graphite filter plates 40 can filter particulate impurities such as carbon impurities floating in the silicon carbide atmosphere layer by layer and in multiple gradients, which helps to reduce defects such as microtubes caused by carbon encapsulation on the single crystal surface, and thus helps to improve the growth quality of silicon carbide crystals.

[0048] In some embodiments of the present invention, reference is made to... Figure 1 and Figure 2 As shown, in the axial direction of the support rod 31, two adjacent layers of graphite filter plates 40 are located on the radial sides of the support rod 31. It can be understood that by arranging two adjacent layers of graphite filter plates 40 on the radial sides of the support rod 31 in the axial direction, the graphite filter plates 40 can be evenly distributed in the airflow direction, which is beneficial to improving the filtration and diversion effect.

[0049] In some embodiments of the present invention, reference is made to... Figure 1 and Figure 2As shown, the pores 41 on the same graphite filter plate 40 have equal diameters, and in the upward direction, the parameters of the upper graphite filter plate 40 are smaller than those of the lower graphite filter plate 40. The parameters are at least one of pore diameter, porosity, and thickness. Porosity refers to the percentage of pore volume in a bulk material to the total volume of the material in its natural state. A higher porosity indicates a larger pore space within the graphite filter plate 40. For example, the parameter can be one of pore diameter, porosity, and thickness; or two of pore diameter, porosity, and thickness; or even a combination of pore diameter, porosity, and thickness.

[0050] Understandably, by making the thickness of the upper graphite filter plate 40 less than that of the lower graphite filter plate 40 in the upward direction, the lowermost graphite filter plate 40 can react more fully with the silicon-rich atmosphere, reducing the corrosion of the upper graphite filter plate 40 by the silicon-rich atmosphere, which is beneficial to further eliminating the corrosiveness of the silicon carbide atmosphere. By making the pore size or porosity of the upper graphite filter plate 40 less than that of the lower graphite filter plate 40 in the upward direction, it is beneficial to improve the layer-by-layer filtration effect and reduce the content of particulate impurities in the silicon carbide atmosphere flowing to the seed crystal 21.

[0051] For example, in one example of the present invention, reference is made to... Figure 2 As shown, the multiple graphite filter plates 40 are arranged sequentially from bottom to top as a first graphite filter plate 4a, a second graphite filter plate 4b, and a third graphite filter plate 4c. The parameters of the uppermost third graphite filter plate 4c are smaller than those of the middle second graphite filter plate 4b, and the parameters of the second graphite filter plate 4b are smaller than those of the bottommost first graphite filter plate 4a. The parameters are pore size, porosity, and thickness. Specifically, the bottommost first graphite filter plate 4a has the largest pore size, the largest porosity, and the largest thickness. This further improves the overall ability of the multiple graphite filter plates 40 to eliminate the corrosiveness of the silicon carbide atmosphere and ensures the filtration effect on particulate impurities, which is beneficial to improving the overall working performance of the multiple graphite filter plates 40 and further improving the quality of the silicon carbide crystals. Optionally, refer to... Figure 2 As shown, the first graphite filter plate 4a is made of graphite material with higher corrosion resistance, that is, the corrosion resistance of the first graphite filter plate 4a is greater than that of the second graphite filter plate 4b and the third graphite filter plate 4c.

[0052] In some embodiments of the present invention, reference is made to... Figure 2As shown, taking the plane passing through the central axis of the support rod 31 as the reference plane, the radial inner edge of the guide vane 32 located in the same layer on the reference plane is higher than the radial outer edge of the guide vane 32, and the angle between the lower surface of the guide vane 32 located in the same layer and the horizontal plane is α, where α satisfies: 30°≤α≤60°. In other words, the angle α between the lower surface of the guide vane 32 located in the same layer and the horizontal plane can take any value between 30° and 60°. For example, the angle α between the lower surface of the guide vane 32 located in the same layer and the horizontal plane can be 30°, 35°, 40°, 45°, 50°, 55°, or 60°, etc.

[0053] It is understandable that by making the radial inner edge of the guide vane 32 located in the same layer on the reference plane higher than the radial outer edge of the guide vane 32, and the angle between the lower surface of the guide vane 32 located in the same layer and the horizontal plane is 30°-60°, the guide vane 32 can guide the layer-by-layer filtered silicon carbide atmosphere to converge towards the center of the seed crystal 21, which is beneficial to suppressing or reducing the formation of polycrystalline silicon carbide at the outer edge of the crystal.

[0054] In some embodiments of the present invention, reference is made to... Figure 3 As shown, the inner peripheral wall of the crucible body 10 is provided with a spiral groove 11. The spiral groove 11 matches the shape of the guide vane 32, and the outer edge of the guide vane 32 engages with the spiral groove 11. It can be understood that by engaging the outer edge of the guide vane 32 with the spiral groove 11, it is beneficial to ensure that most of the sublimated silicon carbide atmosphere flows upward through the spiral airflow channel 33, preventing the silicon carbide gas from flowing directly along the inner peripheral wall of the crucible body 10 to the seed crystal 21. This ensures that the graphite filter plate 40 reacts fully with the Si-rich atmosphere and also helps to ensure the filtering effect of the graphite filter plate 40 on particulate impurities in the silicon carbide atmosphere. For example, in one example, when installing the guide 30 into the crucible body 10, the bottom of the guide 30 can be inserted into the upper end of the spiral groove 11 first, and then the guide 30 can be rotated downward into the spiral groove 11. This is convenient to operate and facilitates reliable positioning of the guide 30.

[0055] And / or, refer to Figure 3 As shown, the bottom wall of the crucible body 10 is provided with a fixing groove 12, and the bottom end of the support rod 31 is engaged with the fixing groove 12. It can be understood that by engaging the bottom end of the support rod 31 with the fixing groove 12, reliable positioning of the support rod 31 can be ensured, and the structure is simple and inexpensive.

[0056] In some embodiments of the present invention, reference is made to... Figure 4As shown, the silicon carbide crystal growth apparatus 100 further includes a driving device 50, which is located below the crucible body 10. The bottom of the support rod 31 passes through the crucible body 10 and is connected to the driving device 50. The driving device 50 is adapted to drive the flow guide 30 to rotate at different speeds, and the outer edge of the flow guide blade 32 does not contact the inner peripheral wall of the crucible body 10. For example, see reference... Figure 4 As shown, the flow guide 30 is located directly below the seed crystal 21. The diameter of the flow guide 30 is equal to the diameter of the seed crystal 21 and smaller than the inner diameter of the crucible body 10. The driving device 50 can drive the flow guide 30 to rotate clockwise. The driving device 50 can control the flow guide 30 to rotate at ultra-low speed, low speed, medium speed, high speed or ultra-high speed.

[0057] It is understandable that the rotation of the guide vane 32 can drive the silicon carbide atmosphere to rise. The operator can control the rotation of the guide vane 30 at different speeds through the drive device 50, thereby controlling the rising speed of the silicon carbide atmosphere. The user can control the rotation speed of the guide vane 30 according to the actual situation to maintain the growth rate of the silicon carbide crystal within a set range (e.g., 0.5 mm / h-1.5 mm / h), which is conducive to ensuring uniform growth of silicon carbide crystal and improving the growth quality of the crystal.

[0058] In some embodiments of the present invention, reference is made to... Figures 4-6 As shown, the silicon carbide crystal growth apparatus 100 further includes: a first flow guide shroud 60, which covers the outside of the flow guide member 30. The bottom of the first flow guide shroud 60 has a first opening 61 facing the silicon carbide raw material 200, and the top of the first flow guide shroud 60 has a second opening 62 facing the seed crystal 21. In the direction from bottom to top, the outer diameter of the flow guide blade 32 (refer to...) Figure 6 Both the outer contour of the first shroud 60 and the inner diameter of the first shroud 60 gradually decrease. For example, the outer contour of the first shroud 60 is formed into a frustum shape, and the first shroud 60 defines a first flow cavity with an isosceles trapezoidal cross-section.

[0059] Understandably, by gradually reducing the inner diameter of the first guide shroud 60 in the upward direction, the first guide shroud 60 can guide the silicon carbide atmosphere to the center of the seed crystal 21, which helps to suppress the formation of polycrystalline silicon carbide on the outer edge of the crystal. At the same time, in the upward direction, the outer diameter of the guide vane 32 and the inner diameter of the first guide shroud 60 are both gradually reduced, which helps to ensure that most of the silicon carbide atmosphere flows upward through the spiral airflow channel 33, which helps to ensure that the graphite filter plate 40 is in full contact with the silicon carbide atmosphere and to fully filter particulate impurities in the silicon carbide atmosphere. This helps to further reduce defects such as microtubes in the silicon carbide crystal and improve the growth quality of the silicon carbide crystal.

[0060] In some embodiments of the present invention, reference is made to... Figure 6As shown, the first flow guide shroud 60 is provided with a plurality of flow guide holes 63, which penetrate the first flow guide shroud 60 in the thickness direction. The silicon carbide crystal growth apparatus 100 also includes a second flow guide shroud 70, which covers the outside of the first flow guide shroud 60 and the inner wall of the second flow guide shroud 70 is spaced apart from the outer wall of the first flow guide shroud 60. The top of the second flow guide shroud 70 has a third opening 71 that is directly opposite to the seed crystal 21 and the second opening 62.

[0061] For example, refer to Figure 6 As shown, the first flow guide shroud 60 is formed in the shape of a frustum, and a first flow guide cavity with an isosceles trapezoidal cross-section is defined inside the first flow guide shroud 60. The second flow guide shroud 70 is disposed outside the first flow guide shroud 60, and a second flow guide cavity with an isosceles trapezoidal cross-section is defined inside the second flow guide shroud 70. The first flow guide cavity and the second flow guide cavity are coaxially arranged. The height of the second flow guide shroud 70 is greater than the height of the first flow guide shroud 60. The cross-sectional area of ​​the third opening 71 is greater than the cross-sectional area of ​​the seed crystal 21, and the cross-sectional area of ​​the seed crystal 21 is greater than the cross-sectional area of ​​the second opening 62. Optionally, both the first flow guide shroud 60 and the second flow guide shroud 70 are graphite parts.

[0062] Understandably, during the crystal growth process, the flow holes 63 on the first flow guide 60 can filter particulate impurities in the silicon carbide atmosphere flowing through it, which helps to further reduce defects such as microtubes in the silicon carbide crystal. At the same time, when the flow guide 30 rotates, the flow velocity of the silicon carbide atmosphere in the first flow guide 60 is greater than the flow velocity of the silicon carbide atmosphere between the second flow guide 70 and the first flow guide 60. This helps to make the growth rate of the middle part of the silicon carbide crystal slightly greater than the growth rate of the outer ring, which helps to make the silicon carbide crystal exhibit a slightly convex shape in the middle, which helps to reduce the internal stress of the silicon carbide crystal and improve the quality of the silicon carbide crystal.

[0063] In some embodiments of the present invention, reference is made to... Figure 7As shown, the silicon carbide crystal growth apparatus 100 further includes: a third flow guide shroud 80, which is disposed within the receiving cavity 13. The third flow guide shroud 80 defines a first chamber 81, a second chamber 82, and a third chamber 83 arranged sequentially from bottom to top. In the direction from bottom to top, the flow area of ​​the first chamber 81 gradually decreases, the flow area of ​​the second chamber 82 first decreases and then increases, and the flow area of ​​the third chamber 83 gradually increases. The flow guide blade 32 includes a first spiral segment 321, a second spiral segment 322, and a third spiral segment 323 connected sequentially from bottom to top. The first spiral segment 321, the second spiral segment 322, and the third spiral segment 323 are respectively disposed within the first chamber 81, the second chamber 82, and the third chamber 83. In the direction from bottom to top, the outer diameter of the first spiral segment 321 gradually decreases, the outer diameter of the second spiral segment 322 first decreases and then increases, and the outer diameter of the third spiral segment 323 gradually increases. The first spiral section 321, the second spiral section 322, and the third spiral section 323 are each provided with multiple graphite filter plates 40 arranged in layers along the axial direction of the support rod 31. Optionally, the third guide shroud 80 is a graphite component, and the first spiral section 321, the second spiral section 322, and the third spiral section 323 are a single piece.

[0064] Understandably, during crystal growth, silicon carbide gas can flow spirally upwards towards the seed crystal 21 through the first spiral section 321, the second spiral section 322, and the third spiral section 323. The first spiral section 321 can draw up the silicon carbide gas by rotating. The collected silicon carbide gas is first accelerated and then decelerated in the second chamber 82 and flows towards the third chamber 83. This ensures that the multiple graphite filter plates 40 on the first spiral section 321 and the second spiral section 322 react fully with the silicon-rich atmosphere and fully filter the impurity particles in the silicon carbide atmosphere. Furthermore, since the flow rate of the silicon carbide atmosphere in the third chamber 83 is slower, the corrosion of the graphite filter plates 40 in the third chamber 83 is less and the filtration capacity is stronger. This can further eliminate the corrosiveness of the silicon carbide atmosphere flowing towards the seed crystal 21 and reduce the content of particulate impurities in the silicon carbide atmosphere flowing towards the seed crystal 21, which is beneficial to further ensure the growth quality of the silicon carbide crystal.

[0065] In some embodiments of the present invention, reference is made to... Figure 7 As shown, the silicon carbide crystal growth apparatus 100 further includes: a shielding cover 84, which is connected to the third flow guide shroud 80 and is located at the opening at the top of the third chamber 83. A flow guide channel 841 is provided at the center of the shielding cover 84, and the flow guide channel 841 is coaxially arranged with the third chamber 83. The shielding cover 84 also has multiple through holes 842 for filtering the airflow. The shielding cover 84 and the third flow guide 30 can be integrally molded.

[0066] Understandably, during the crystal growth process, the shielding cover 84 located at the top opening of the third chamber 83 can filter particulate impurities in the silicon carbide atmosphere flowing through it, which helps to further reduce the content of particulate impurities in the silicon carbide atmosphere flowing to the seed crystal 21. At the same time, the flow rate of silicon carbide gas flowing out from the guide channel 841 in the center of the shielding cover 84 is greater than the flow rate of silicon carbide gas flowing out from the multiple through holes 842, which can make the growth rate of the middle part of the silicon carbide crystal slightly greater than the growth rate of the outer ring. This is beneficial to make the silicon carbide crystal exhibit a slightly convex shape in the middle, which helps to reduce the internal stress of the silicon carbide crystal and improve the quality of the silicon carbide crystal.

[0067] In some embodiments of the present invention, reference is made to... Figure 7 As shown, the drive device 50 includes a first motor 51, a second motor 52, and a third motor 53. The support rod 31 includes a first support rod 311, a second support rod 312, and a third support rod 313. The first motor 51 is connected to the first helical segment 321 through the first support rod 311. The second motor 52 is connected to the second helical segment 322 through the second support rod 312. The third motor 53 is connected to the third helical segment 323 through the third support rod 313. The central axes of the first support rod 311, the second support rod 312, and the third support rod 313 are on the same straight line. The first support rod 311 is arranged around the second support rod 312 and is rotatably engaged with the second support rod 312. The second support rod 312 is arranged around the third support rod 313 and is rotatably engaged with the third support rod 313.

[0068] For example, the first motor 51 is connected to the first support rod 311 through the first transmission element 511, the second motor 52 is connected to the second support rod 312 through the second transmission element 521, and the third motor 53 is connected to the third support rod 313 through the third transmission element 531. The first transmission element 511, the second transmission element 521, and the third transmission element 531 can be a belt drive assembly or a gear drive assembly, etc. The length of the first support rod 311 is less than the length of the second support rod 312, and the length of the second support rod 312 is less than the length of the third support rod 313. The first motor 51, the second motor 52, and the third motor 53 are respectively connected to the control system of the silicon carbide crystal growth device 100, thereby realizing intelligent control of the rotation speed of the first helical segment 321, the second helical segment 322, and the third helical segment 323.

[0069] Understandably, by setting up the first motor 51, the second motor 52, and the third motor 53, as well as the first support rod 311, the second support rod 312, and the third support rod 313 with a collar design, the rotation speeds of the first spiral segment 321, the second spiral segment 322, and the third spiral segment 323 can be independently controlled. The first spiral segment 321, the second spiral segment 322, and the third spiral segment 323 can be combined with different rotation speeds to further precisely control the rising speed of the silicon carbide atmosphere, thereby helping to ensure that the growth rate of silicon carbide crystals is maintained within the set range, and further improving the growth quality of silicon carbide crystals.

[0070] Other components of the silicon carbide crystal growth apparatus 100 according to embodiments of the present invention, such as the quartz cover 91, the heat insulation felt 92, the induction coil 93, etc., and their operation are known to those skilled in the art and will not be described in detail here.

[0071] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and 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. Therefore, they should not be construed as limitations on this invention.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0073] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0076] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A silicon carbide crystal growth apparatus, characterized in that, include: The crucible body has a top-open receiving cavity, the bottom of which is filled with silicon carbide raw material; A crucible lid is located at the open end of the crucible body, and a seed crystal is attached to the inside of the crucible lid. A flow guide is disposed within the receiving cavity. The flow guide includes a support rod and a flow guide blade. The support rod is vertically arranged, and the flow guide blade is arranged around the support rod and extends spirally along the axial direction of the support rod. The radial inner wall of the flow guide blade is connected to the radial outer wall of the support rod. The flow guide blade and the support rod define a spiral airflow channel. A graphite filter plate is disposed within the spiral airflow channel and connected between adjacent layers of the spiral airflow channel. The radially inner side of the graphite filter plate is connected to the radially outer side of the support rod. The graphite filter plate has multiple filter holes, each of which penetrates the graphite filter plate in the thickness direction. There are multiple graphite filter plates, which are arranged in layers along the axial direction of the spiral airflow channel. In the axial direction of the support rod, adjacent layers of graphite filter plates are located on the radial sides of the support rod, respectively. Also includes: A driving device is provided below the crucible body, and the bottom of the support rod passes through the crucible body and is connected to the driving device. The driving device is adapted to drive the guide to rotate at different speeds. A first flow guide shroud is disposed on the outside of the flow guide member. The bottom of the first flow guide shroud has a first opening facing the silicon carbide raw material, and the top of the first flow guide shroud has a second opening facing the seed crystal. The outer diameter of the flow guide blade and the inner diameter of the first flow guide shroud gradually decrease from bottom to top. The first flow guide shroud has a plurality of flow guide holes, which penetrate the first flow guide shroud in the thickness direction. The silicon carbide crystal growth apparatus further includes a second flow guide shroud, which is disposed on the outside of the first flow guide shroud, and the inner wall of the second flow guide shroud is spaced apart from the outer wall of the first flow guide shroud. The top of the second flow guide shroud has a third opening facing the seed crystal and the second opening.

2. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The plurality of filter holes located on the same graphite filter plate have equal pore sizes, and in the direction from bottom to top, the parameters of the upper graphite filter plate are smaller than those of the lower graphite filter plate, wherein the parameters are at least one of pore size, porosity, and thickness.

3. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, Using the plane passing through the central axis of the support rod as a reference plane, the radial inner edge of the guide vane located on the same layer on the reference plane is higher than the radial outer edge of the guide vane, and the angle between the lower surface of the guide vane located on the same layer and the horizontal plane is α, where α satisfies: 30°≤α≤60°.

4. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The inner circumferential wall of the crucible body is provided with a spiral groove, the spiral groove is matched with the shape of the guide vane, the outer edge of the guide vane is engaged with the spiral groove, and / or, the bottom wall of the crucible body is provided with a fixing groove, the bottom end of the support rod is engaged with the fixing groove.

5. The silicon carbide crystal growth apparatus according to any one of claims 1-4, characterized in that, Also includes: The third flow guide is disposed within the receiving cavity and defines a first chamber, a second chamber, and a third chamber arranged sequentially from bottom to top. In the direction from bottom to top, the flow area of ​​the first chamber gradually decreases, the flow area of ​​the second chamber first decreases and then increases, and the flow area of ​​the third chamber gradually increases. The flow guide blade includes a first spiral segment, a second spiral segment, and a third spiral segment connected sequentially from bottom to top. The first spiral segment, the second spiral segment, and the third spiral segment are respectively disposed within the first chamber, the second chamber, and the third chamber. In the direction from bottom to top, the outer diameter of the first spiral segment gradually decreases, the outer diameter of the second spiral segment first decreases and then increases, and the outer diameter of the third spiral segment gradually increases.

6. The silicon carbide crystal growth apparatus according to claim 5, characterized in that, Also includes: A shielding cover is connected to the third air guide cover and is located at the open opening at the top of the third chamber. The shielding cover has an air guide channel at its center, which is coaxially arranged with the third chamber. The shielding cover also has multiple through holes for filtering the airflow.

7. The silicon carbide crystal growth apparatus according to claim 5, characterized in that, The driving device includes a first motor, a second motor, and a third motor. The support rod includes a first support rod, a second support rod, and a third support rod. The first motor is connected to the first helical segment via the first support rod. The second motor is connected to the second helical segment via the second support rod. The third motor is connected to the third helical segment via the third support rod. The central axes of the first support rod, the second support rod, and the third support rod are on the same straight line. The first support rod is arranged around the second support rod and is rotatably engaged with the second support rod. The second support rod is arranged around the third support rod and is rotatably engaged with the third support rod.

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