A graphite crucible capable of actively maintaining temperature gradient and a method for preparing silicon carbide

Abstract

The present invention discloses a graphite crucible capable of actively maintaining a temperature gradient and a method for preparing silicon carbide, and relates to the field of silicon carbide crystal growth equipment. The graphite crucible capable of actively maintaining a temperature gradient comprises a main body and a cover body, wherein the main body has a growth chamber with an opening at the top, the cover body selectively covers the growth chamber, the growth chamber has a bottom powder material area and a top growth material area, the bottom powder material area is used to hold silicon carbide powder; a first flow channel extending downward is arranged in the side wall of the main body, the first flow channel has a first input port for introducing a heat exchange medium, and a first output port for discharging the heat exchange medium; the first flow channel comprises a top spiral section between the first input port and the first output port, and the top spiral section surrounds the circumference of the top growth area. Therefore, the graphite crucible capable of actively maintaining a temperature gradient provided by the present invention can actively maintain an axial temperature gradient, and ensure that silicon carbide crystals continue to grow normally.

Description

Technical Field

[0001] The invention relates to the field of silicon carbide crystal growth equipment, and in particular to a graphite crucible capable of actively maintaining a temperature gradient and a method for preparing silicon carbide. Background Art

[0002] At present, the physical vapor transport method is often used to grow silicon carbide crystals on the market. Specifically, a graphite crucible is used, silicon carbide powder is placed at the bottom of the graphite crucible, and a seed crystal is installed on the inner surface of the crucible cover. During growth, the silicon carbide powder is heated in a vacuum environment to sublimate it to form a growth atmosphere. The growth atmosphere rises upward under the influence of the axial temperature gradient and finally recrystallizes on the surface of the seed crystal with a lower temperature to achieve the growth of silicon carbide crystals.

[0003] In practical applications, as the silicon carbide crystal grows, its growth surface will gradually approach the material surface at the bottom of the crucible, and the axial temperature gradient will gradually decrease naturally, which is not conducive to the continuous growth of the silicon carbide crystal. Summary of the invention

[0004] The object of the present invention is to provide a graphite crucible which can actively maintain a temperature gradient, and can actively maintain an axial temperature gradient during the growth of silicon carbide crystals, thereby ensuring that the silicon carbide crystals continue to grow normally.

[0005] Another object of the present invention is to provide a method for preparing silicon carbide, which can actively maintain the axial temperature gradient during the growth of silicon carbide crystals to ensure the continuous and normal growth of silicon carbide crystals.

[0006] The embodiment of the present invention provides a technical solution:

[0007] A graphite crucible capable of actively maintaining a temperature gradient, comprising a main body and a cover, wherein the main body has a growth chamber with an open top, the cover selectively covers the growth chamber, the growth chamber has a bottom powder material area and a top growth area, the bottom powder material area is used to hold silicon carbide powder;

[0008] A first flow channel is arranged in the side wall of the main body, and the first flow channel has a first input port for introducing a heat exchange medium, and a first output port for discharging the heat exchange medium, and the first flow channel extends downward from the first input port to the first output port; the first flow channel includes a top spiral section between the first input port and the first output port, and the top spiral section surrounds the circumference of the top growth zone.

[0009] In an optional embodiment, the first flow channel also includes a bottom spiral section, one end of which is connected to an end of the top spiral section away from the first input port, and the other end spirally extends downward to the first output port, and the bottom spiral section surrounds the circumference of the bottom powder area.

[0010] In an optional embodiment, the first input port is arranged on the top wall of the main body, and the first output port is arranged on the bottom wall of the main body.

[0011] In an optional embodiment, a second flow channel is provided in the area of ​​the side wall of the main body corresponding to the bottom powder zone, and the second flow channel has a second input port for introducing a heat exchange medium, and a second output port for discharging the heat exchange medium. From the second input port to the second output port, the second flow channel spirally extends downward and surrounds the circumference of the bottom powder zone.

[0012] In an optional embodiment, the second input port is arranged on the top wall of the main body, and the second output port is arranged on the bottom wall of the main body.

[0013] In an optional embodiment, the first flow channel further comprises a bottom straight segment, one end of the bottom straight segment is connected to an end of the top spiral segment away from the first input port, and the other end of the bottom straight segment vertically extends downward to the first output port;

[0014] The second flow channel includes a top straight section and a spiral main section, the spiral main section surrounds the circumference of the bottom powder area, the bottom end of the spiral main section is connected to the second output port, the top straight section is connected to one end of the spiral main section away from the second output port, and the other end extends vertically upward to the second input port.

[0015] In an optional embodiment, a third flow channel is provided in the cover body, and the third flow channel has a third input port for introducing a heat exchange medium, and a third output port for discharging the heat exchange medium, the third input port is provided at a horizontal edge position of the cover body, and the third output port is provided at a horizontal center position of the cover body.

[0016] In an optional embodiment, the third flow channel extends spirally in a plane parallel to a horizontal plane from the third input port to the third output port.

[0017] An embodiment of the present invention further provides a method for preparing silicon carbide, which is applied to the aforementioned graphite crucible capable of actively maintaining a temperature gradient, and the method for preparing silicon carbide comprises:

[0018] Arranging silicon carbide powder in the bottom powder area;

[0019] After the seed crystals are arranged on the inner surface of the cover, the cover is used to cover the growth chamber;

[0020] heating the graphite crucible so that a vertical upward temperature gradient is formed in the growth chamber;

[0021] The first cooling gas is continuously injected into the first input port so that the first cooling gas dissipates heat to different areas on the first flow path in decreasing degrees in sequence.

[0022] In an optional embodiment, after the step of heating the graphite crucible so that a vertical upward temperature gradient is formed in the growth chamber, the method for preparing silicon carbide further comprises:

[0023] The third cooling gas is continuously injected into the third input port so that the third cooling gas dissipates heat to different areas on the third flow path in descending degrees in sequence.

[0024] Compared with the prior art, the graphite crucible provided by the present invention can actively maintain a temperature gradient. In the process of normal growth of silicon carbide crystals, a heat exchange medium is input into the first input port of the first flow channel. As the heat exchange medium flows in the first flow channel, the heat of different parts of the main body is taken away. Since the top spiral section of the first flow channel surrounds the circumference of the top growth zone and extends spirally downward, the heat exchange medium flows downward along the spiral in the first flow channel, and the temperature gradually increases during the flow. Compared with the vertical upward temperature gradient, the heat exchange medium performs stronger heat dissipation to the lower temperature area in the top growth zone and weaker heat dissipation to the higher temperature area, thereby maintaining the size of the axial temperature gradient and avoiding the situation where the temperature gradient gradually decreases as the silicon carbide crystal grows. Therefore, the beneficial effects of the graphite crucible that can actively maintain a temperature gradient provided by the present invention include: being able to actively maintain an axial temperature gradient to ensure that the silicon carbide crystal continues to grow normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative work.

[0026] Figure 1 A cross-sectional view of a graphite crucible capable of actively maintaining a temperature gradient provided in accordance with a first embodiment of the present application;

[0027] Figure 2 A cross-sectional view of a graphite crucible capable of actively maintaining a temperature gradient provided in accordance with a second embodiment of the present application;

[0028] Figure 3 A schematic structural diagram of a cover body provided in a third embodiment of the present application;

[0029] Figure 4 A flowchart of a method for preparing silicon carbide provided in accordance with the fourth embodiment of the present application.

[0030] Icon: 100-graphite crucible; 110-main body; 111-bottom powder area; 112-top growth area; 120-cover; 130-first flow channel; 131-first input port; 132-first output port; 133-top spiral section; 134-bottom spiral section; 135-bottom straight section; 140-second flow channel; 141-second input port; 142-second output port; 143-top straight section; 144-spiral main body section; 150-third flow channel; 151-third input port; 152-third output port; 200-silicon carbide powder. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0035] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0038] First embodiment

[0039] See also Figure 1 , Figure 1 FIG. 1 is a cross-sectional view of a graphite crucible 100 capable of actively maintaining a temperature gradient according to a first embodiment of the present application.

[0040] The graphite crucible 100 capable of actively maintaining a temperature gradient provided in this embodiment is used for growing silicon carbide crystals. The graphite crucible 100 can actively maintain an axial temperature gradient to ensure that the silicon carbide crystals continue to grow normally, and can also improve horizontal temperature uniformity and growth quality.

[0041] The graphite crucible 100 includes a main body 110 and a cover 120 . The main body 110 has a growth chamber with an open top. The cover 120 selectively covers the growth chamber. The growth chamber has a bottom powder area 111 and a top growth area 112 . The bottom powder area 111 is used to hold silicon carbide powder 200 .

[0042] It is understandable that, in practical applications, the silicon carbide powder 200 is placed in the powder area 111 at the bottom of the growth chamber, the seed crystal is pasted on the inner surface of the cover 120, and then the cover 120 is covered on the top of the main body 110 to seal the growth chamber. The silicon carbide powder 200 is then heated to sublimate to form a growth atmosphere, and moves to the surface of the seed crystal under the influence of the axial temperature gradient and precipitates crystals.

[0043] In the prior art, the graphite crucible 100 is placed in a crystal growth furnace to grow silicon carbide crystals. As the growth process proceeds, the filling gas in the crystal growth furnace will continue to flow upward due to the influence of temperature, and will gather at the top of the graphite crucible 100, causing the temperature of the area where the crystal growth surface inside the graphite crucible 100 is located to gradually increase, making the axial temperature gradient smaller. In addition, as the silicon carbide crystal continues to grow, its growth surface gradually extends downward, which also causes the axial temperature gradient to become smaller.

[0044] Furthermore, since the periphery of the graphite crucible 100 is closer to the heat source in the horizontal direction, the peripheral temperature of the internal thermal field of the graphite crucible 100 is higher than the central temperature. The temperature difference between the two causes the growth atmosphere to crystallize more easily at the center of the seed crystal, resulting in poor growth uniformity.

[0045] In order to solve the above problems, the graphite crucible 100 provided in this embodiment has a first flow channel 130 disposed in the side wall of the main body 110. The first flow channel 130 has a first input port 131 for introducing a heat exchange medium and a first output port 132 for discharging the heat exchange medium. The first flow channel 130 extends downward from the first input port 131 to the first output port 132. The first flow channel 130 includes a top spiral section 133 between the first input port 131 and the first output port 132. The top spiral section 133 surrounds the circumference of the top growth region 112.

[0046] It should be noted that the heat exchange medium corresponding to the first flow channel 130 in this embodiment is mainly used to dissipate heat and cool the main body 110. After the heat exchange medium in a low temperature state enters the first flow channel 130 from the first input port 131, it flows downward in the top spiral section 133, continuously exchanges heat with the main body 110 during the flow process, and the temperature of the heat exchange medium gradually increases, and finally flows out of the first output port 132 in a high temperature state.

[0047] On the one hand, the temperature of the heat exchange medium increases as it flows downward. Compared with the vertical upward temperature gradient, the heat exchange medium dissipates heat more strongly to the lower temperature area in the top growth zone 112 and dissipates heat less strongly to the higher temperature area, thereby effectively maintaining the size of the axial temperature gradient and avoiding the situation where the temperature gradient gradually decreases with the growth of the silicon carbide crystal. In addition, the graphite crucible 100 provided in this embodiment can also finely control the axial temperature gradient. For example, when the axial temperature gradient decreases due to the gradual growth of the silicon carbide crystal, the axial temperature gradient can be maintained by increasing the flow rate of the heat exchange medium, thereby stabilizing the growth rate and interface morphology of the silicon carbide crystal and reducing defects.

[0048] On the other hand, the heat exchange medium cools and dissipates the side wall of the main body 110 during the flow along the top spiral section 133, thereby effectively reducing the temperature of the horizontal edge of the thermal field inside the graphite crucible 100, thereby effectively reducing the temperature difference between the horizontal edge and the center of the thermal field, and significantly improving the growth uniformity of the silicon carbide crystal in the horizontal direction. In fact, the radial temperature gradient can also be reduced or increased according to the needs of different growth stages, thereby maintaining a good micro-convex shape of the growth interface for a long time.

[0049] In fact, in this embodiment, the first flow channel 130 also includes a bottom spiral section 134, one end of the bottom spiral section 134 is connected to one end of the top spiral section 133 away from the first input port 131, and the other end spirally extends downward to the first output port 132, and the bottom spiral section 134 surrounds the circumference of the bottom powder area 111.

[0050] It can be seen that the first flow channel 130 in this embodiment realizes the encirclement of the surrounding side of the growth chamber. After the heat exchange medium enters the first flow channel 130 from the first input port 131, it flows downward in a spiral along the first flow channel 130, passes through the top growth area 112 and the bottom powder area 111 of the growth chamber in turn, and then flows out to the outside from the first output port 132.

[0051] In order to facilitate pipe laying, in this embodiment, the first input port 131 is disposed on the top wall of the main body 110, and the first output port 132 is disposed on the bottom wall of the main body 110. In other embodiments, the first input port 131 and the first output port 132 may also be disposed on the outer side wall of the main body 110 according to actual application conditions.

[0052] It should be noted that, in other embodiments, in order to avoid batch processing and save production costs, the graphite crucible 100 provided in this embodiment can be used in combination with a crucible of a traditional structure.

[0053] Specifically, a conventional crucible containing powder and equipped with seed crystals can be placed inside the graphite crucible 100 provided in this embodiment to grow silicon carbide crystals in the conventional crucible. The graphite crucible 100 provided in this embodiment regulates the axial temperature gradient of the conventional crucible.

[0054] Second embodiment

[0055] See also Figure 2 , Figure 2 FIG. 1 is a cross-sectional view of a graphite crucible 100 provided in accordance with a second embodiment of the present application.

[0056] It can be understood that the temperature of the bottom powder zone 111 is always higher than the temperature of the top growth zone 112, and the silicon carbide powder 200 in the bottom powder zone 111 forms a growth atmosphere and enters the top growth zone 112. The temperature condition of the top growth zone 112 affects the flow direction of the growth atmosphere, while the bottom powder zone 111 has little effect on the flow condition of the growth atmosphere.

[0057] Therefore, in order to shorten the flow time of the heat exchange medium in the first flow channel 130 and improve the heat exchange efficiency of the heat exchange medium, thereby obtaining a better axial temperature gradient maintenance effect, compared with the first embodiment, in this embodiment, the first flow channel 130 does not include a bottom spiral section 134, but includes a bottom straight section 135, one end of the bottom straight section 135 is connected to an end of the top spiral section 133 away from the first input port 131, and the other end extends vertically downward to the first output port 132.

[0058] In another embodiment, the first output port 132 can be directly opened on the outer wall of the main body 110 at the interface between the top growth area 112 and the bottom powder area 111, that is, the top spiral section 133 is the entire structure of the first flow channel 130, which can further improve the heat exchange efficiency of the heat exchange medium.

[0059] In order to achieve precise control of the temperature of the bottom powder zone 111, thereby obtaining higher growth efficiency and growth quality, in this embodiment, a second flow channel 140 is provided in the area corresponding to the side wall of the main body 110 and the bottom powder zone 111. The second flow channel 140 has a second input port 141 for introducing a heat exchange medium, and a second output port 142 for discharging the heat exchange medium. From the second input port 141 to the second output port 142, the second flow channel 140 spirally extends downward and surrounds the circumference of the bottom powder zone 111.

[0060] In practical applications, the graphite crucible 100 provided in this embodiment can inject heat exchange medium into the second flow channel 140 through the second input port 141, and achieve different degrees of heat exchange with the corresponding areas of the side wall of the main body 110 by controlling the temperature and flow of the injected heat exchange medium, thereby achieving precise control of the temperature of the bottom powder area 111 and obtaining higher growth efficiency and better growth quality.

[0061] Similarly, in order to facilitate pipe laying, in this embodiment, the second input port 141 is arranged on the top wall of the main body 110, and the second output port 142 is arranged on the bottom wall of the main body 110. Specifically, the second flow channel 140 includes a top straight section 143 and a spiral main section 144, the spiral main section 144 surrounds the circumference of the bottom powder area 111, the bottom end of the spiral main section 144 is connected to the second output port 142, the top straight section 143 is connected to one end of the spiral main section 144 away from the second output port 142, and the other end extends vertically upward to the second input port 141.

[0062] In this embodiment, the first flow channel 130 passes through the bottom powder area 111 through the bottom straight section 135 to reach the first output port 132 on the bottom wall of the main body 110, thereby avoiding affecting the temperature of the bottom powder area 111. The second flow channel 140 passes through the top growth area 112 through the top straight section 143 to reach the second input port 141 on the top wall of the main body 110, thereby avoiding affecting the axial temperature gradient of the top growth area 112.

[0063] It can be seen that the graphite crucible 100 provided in this embodiment can independently control the temperatures of the top growth zone 112 and the bottom powder zone 111 through the first flow channel 130 and the second flow channel 140, thereby achieving refined control of the temperature of the growth chamber and obtaining higher growth efficiency and better growth quality.

[0064] In order to improve the flow efficiency of the heat exchange medium in the second flow channel 140, the second input port 141 may be opened on the outer wall of the main body 110 at the interface between the top growth area 112 and the bottom powder area 111. In addition, in another embodiment, in order to simplify the structure, the second output port 142 and the first output port 132 may be the same opening opened on the main body 110.

[0065] Third embodiment

[0066] Please refer to Figure 3 , Figure 3 FIG. 1 is a schematic structural diagram of a cover body 120 in a third embodiment of the present application.

[0067] The graphite crucible 100 capable of actively maintaining a temperature gradient provided in the third embodiment of the present application further improves the structure of the cover 120 on the basis of the first embodiment or the second embodiment.

[0068] Specifically, in order to further improve the growth uniformity of silicon carbide crystals, in this embodiment, a third flow channel 150 is arranged in the cover body 120, and the third flow channel 150 has a third input port 151 for introducing a heat exchange medium, and a third output port 152 for discharging the heat exchange medium. The third input port 151 is arranged at a horizontal edge position of the cover body 120, and the third output port 152 is arranged at a horizontal center position of the cover body 120.

[0069] Similarly, the heat exchange medium corresponding to the third flow channel 150 is mainly used to dissipate heat and cool the cover 120. After the low-temperature heat exchange medium enters the third flow channel 150 from the third input port 151, the temperature of the heat exchange medium gradually increases as it flows along the third flow channel 150 to the third output port 152.

[0070] That is, when the heat exchange medium flows in the third flow, the closer it is to the center of the cover 120, the higher its temperature and the worse the heat dissipation effect. The edge of the cover 120 corresponds to the horizontal edge area of ​​the thermal field, and the center of the cover 120 corresponds to the horizontal center area of ​​the thermal field. Therefore, the heat exchange medium performs stronger heat dissipation on the edge area with higher temperature of the thermal field and weaker heat dissipation on the center area with lower temperature, thereby further reducing the temperature difference between the horizontal edge and the center of the thermal field, and further improving the growth uniformity of the silicon carbide crystal.

[0071] Preferably, in this embodiment, the third flow channel 150 spirally extends in a plane parallel to the horizontal plane from the third input port 151 to the third output port 152. It should be noted that the number of the first flow channel 130, the second flow channel 140 and the third flow channel 150 is not fixed and can be configured according to actual application conditions.

[0072] It should be noted that the heat exchange medium in this embodiment is a mixed gas of argon and nitrogen. Argon mainly plays a heat dissipation effect. By controlling the proportion of nitrogen, the nitrogen doping amount of the silicon carbide crystal can be adjusted and better nitrogen doping uniformity can be obtained. In other embodiments, the specific composition of the heat exchange medium can be selected according to actual application conditions.

[0073] In summary, the graphite crucible 100 capable of actively maintaining a temperature gradient provided in this embodiment can not only actively maintain an axial temperature gradient during the growth of silicon carbide crystals to ensure continuous and normal growth of silicon carbide crystals, but also improve the growth uniformity of silicon carbide crystals and the growth quality.

[0074] Fourth embodiment

[0075] The fourth embodiment of the present application also provides a method for preparing silicon carbide, which is applied to the graphite crucible 100 that can actively maintain a temperature gradient provided in the third embodiment. Figure 4 , Figure 4 The figure shows a flow chart of the method for preparing silicon carbide, which may include:

[0076] Step S101 , arranging silicon carbide powder 200 in the bottom powder area 111 .

[0077] Step S102 , after the seed crystals are arranged on the inner surface of the cover 120 , the cover 120 is used to seal the growth chamber.

[0078] Step S103 , heating the graphite crucible 100 to form a vertically upward temperature gradient in the growth chamber.

[0079] Step S104 , continuously injecting the first cooling gas into the first input port 131 , so that the first cooling gas dissipates heat to different regions on the first flow channel 130 in descending degrees in sequence.

[0080] Step S105 , continuously injecting the third cooling gas into the third input port 151 , so that the third cooling gas dissipates heat to different areas on the path of the third flow channel 150 in descending degrees in sequence.

[0081] In this embodiment, the first cooling gas and the second cooling gas are both a mixture of argon and nitrogen.

[0082] It can be understood that, in the process of the first cooling gas flowing along the first flow channel 130, on the one hand, the lower temperature area in the top growth zone 112 is subjected to stronger heat dissipation, and the higher temperature area is subjected to weaker heat dissipation, which effectively maintains the size of the axial temperature gradient and avoids the axial temperature gradient from becoming smaller as the silicon carbide crystal grows. On the other hand, the temperature of the horizontal edge of the thermal field inside the graphite crucible 100 is effectively reduced, so that the temperature difference between the horizontal edge and the center of the thermal field is effectively reduced, so that the growth uniformity of the silicon carbide crystal in the horizontal direction is significantly improved.

[0083] When the third cooling gas flows along the third flow channel 150, the edge area with higher temperature of the thermal field is subjected to stronger heat dissipation, while the central area with lower temperature is subjected to weaker heat dissipation, thereby further reducing the temperature difference between the horizontal edge and the center of the thermal field, and further improving the growth uniformity of the silicon carbide crystal.

[0084] In summary, the silicon carbide preparation method provided in this embodiment can not only actively maintain the temperature gradient during the growth of the silicon carbide crystal to ensure the continuous and normal growth of the silicon carbide crystal, but also improve the growth uniformity of the silicon carbide crystal and improve the growth quality.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A graphite crucible capable of actively maintaining a temperature gradient, characterized in that: The invention comprises a main body (110) and a cover body (120), wherein the main body (110) has a growth chamber with an opening at the top, and the cover body (120) selectively covers the growth chamber, wherein the growth chamber has a bottom powder material area (111) and a top growth area (112), and the bottom powder material area (111) is used to contain silicon carbide powder (200); A first flow channel (130) is arranged in the side wall of the main body (110), and the first flow channel (130) has a first input port (131) for introducing a heat exchange medium, and a first output port (132) for discharging the heat exchange medium, and the first flow channel (130) extends downward from the first input port (131) to the first output port (132); the first flow channel (130) includes a top spiral section (133) between the first input port (131) and the first output port (132), and the top spiral section (133) surrounds the circumference of the top growth zone (112).

2. The graphite crucible capable of actively maintaining a temperature gradient according to claim 1, characterized in that: The first flow channel (130) further comprises a bottom spiral section (134), one end of the bottom spiral section (134) being connected to an end of the top spiral section (133) away from the first input port (131), and the other end of the bottom spiral section (134) extending downward in a spiral to the first output port (132), the bottom spiral section (134) surrounding the circumference of the bottom powder material area (111).

3. The graphite crucible capable of actively maintaining a temperature gradient according to claim 1, characterized in that: The first input port (131) is arranged on the top wall of the main body (110), and the first output port (132) is arranged on the bottom wall of the main body (110).

4. The graphite crucible capable of actively maintaining a temperature gradient according to claim 1, characterized in that: A second flow channel (140) is provided in an area of ​​the side wall of the main body (110) corresponding to the bottom powder area (111), and the second flow channel (140) has a second input port (141) for introducing a heat exchange medium, and a second output port (142) for discharging the heat exchange medium. From the second input port (141) to the second output port (142), the second flow channel (140) spirally extends downward and surrounds the circumference of the bottom powder area (111).

5. The graphite crucible capable of actively maintaining a temperature gradient according to claim 4, characterized in that: The second input port (141) is arranged on the top wall of the main body (110), and the second output port (142) is arranged on the bottom wall of the main body (110).

6. The graphite crucible capable of actively maintaining a temperature gradient according to claim 5, characterized in that: The first flow channel (130) further comprises a bottom straight section (135), one end of the bottom straight section (135) is connected to an end of the top spiral section (133) away from the first input port (131), and the other end of the bottom straight section (135) extends vertically downward to the first output port (132); The second flow channel (140) comprises a top straight section (143) and a spiral main section (144); the spiral main section (144) surrounds the circumference of the bottom powder area (111); the bottom end of the spiral main section (144) is connected to the second output port (142); the top straight section (143) is connected to one end of the spiral main section (144) away from the second output port (142), and the other end extends vertically upward to the second input port (141).

7. The graphite crucible capable of actively maintaining a temperature gradient according to claim 1, characterized in that: A third flow channel (150) is arranged in the cover body (120), and the third flow channel (150) has a third input port (151) for introducing a heat exchange medium, and a third output port (152) for discharging the heat exchange medium. The third input port (151) is arranged at a horizontal edge position of the cover body (120), and the third output port (152) is arranged at a horizontal center position of the cover body (120).

8. The graphite crucible capable of actively maintaining a temperature gradient according to claim 7, characterized in that: From the third input port (151) to the third output port (152), the third flow channel (150) extends spirally in a plane parallel to the horizontal plane.

9. A method for preparing silicon carbide, applied to the graphite crucible (100) capable of actively maintaining a temperature gradient as claimed in any one of claims 1 to 8, characterized in that: The silicon carbide preparation method comprises: Arranging silicon carbide powder (200) in the bottom powder area (111); After the seed crystals are arranged on the inner surface of the cover (120), the cover (120) is used to cover the growth chamber; heating the graphite crucible (100) so that a vertical upward temperature gradient is formed in the growth chamber; The first cooling gas is continuously injected into the first input port (131) so that the first cooling gas dissipates heat to different areas on the first flow channel (130) in descending degrees in sequence.

10. The method for preparing silicon carbide according to claim 9, characterized in that: After the step of heating the graphite crucible (100) so that a vertical upward temperature gradient is formed in the growth chamber, the method for preparing silicon carbide further comprises: The third cooling gas is continuously injected into the third input port (151) so that the third cooling gas dissipates heat to different areas on the path of the third flow channel (150) in descending degrees in sequence.

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