Crucible, apparatus and method for silicon carbide crystal growth
By installing a pushing component in the crucible for the growth of silicon carbide crystals and moving the silicon carbide powder in the radial direction, the graphitization problem caused by temperature gradient is solved, and the growth efficiency and quality of silicon carbide crystals are improved.
Patent Information
- Application Number
- CN202411853546.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-03-25
AI Technical Summary
During the growth of silicon carbide crystals, the temperature gradient in the crucible causes graphitization of silicon carbide powder, forming carbon particles, blocking the gas phase transmission channel, affecting growth efficiency and quality.
A crucible for the growth of silicon carbide crystals is designed with a built-in pushing component that can move along the radial direction of the crucible, pushing the silicon carbide powder in the central area of the crucible to the edge area, evenly distribute heat, and adjust the temperature gradient.
By uniformly distributing heat, graphitization is reduced, the generation of carbon particles is reduced, and the growth efficiency and quality of silicon carbide crystals are improved.
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Figure CN119685933A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of semiconductor manufacturing technology, and in particular to a crucible, a device and a method for growing silicon carbide crystals. Background Art
[0002] Silicon carbide (SiC) material is the third generation wide bandgap semiconductor material after Si material and GaAs material. It has excellent physical and chemical properties such as large bandgap width, high critical breakdown electric field strength, high thermal conductivity and good chemical stability. These physical and chemical properties make silicon carbide crystals suitable for applications such as high temperature, high frequency, high voltage and strong radiation.
[0003] At present, the main growth method of silicon carbide crystals is the physical vapor transport (PVT) method. During the growth process, the silicon carbide powder in the crucible sublimates after absorbing heat, and then the gaseous silicon carbide is transported to the seed crystal at the top of the crucible and begins crystal growth. However, during the growth of silicon carbide crystals, since the heat is mainly transferred from the inner wall of the crucible to the center of the crucible by heat conduction, the temperature of the upper part of the crucible is lower than the temperature of the central area of the crucible, and the temperature of the central area of the crucible is always lower than the temperature of the edge area of the crucible. This temperature gradient in the axial and radial directions of the crucible causes the silicon carbide powder to gradually graphitize from the inner wall of the crucible during the growth of silicon carbide crystals, forming carbon particles, which will block the gas phase transmission channel of the gaseous silicon carbide and increase the porosity of the silicon carbide powder at the inner wall of the crucible, ultimately affecting the growth efficiency and quality of the entire silicon carbide crystal. Summary of the invention
[0004] The present disclosure provides a crucible, an apparatus and a method for growing silicon carbide crystals, which can effectively avoid graphitization during the growth of silicon carbide crystals and improve the growth efficiency and quality of silicon carbide crystals.
[0005] The technical solution of the present disclosure is achieved as follows: In a first aspect, the present disclosure provides a crucible for growing silicon carbide crystals, the crucible comprising: A cylindrical crucible body, the crucible body being used to contain silicon carbide powder; and A pusher assembly is disposed in the crucible body and can move along the radial direction of the crucible body during the growth of silicon carbide crystals to push silicon carbide powder in the central area of the crucible body to the edge area of the crucible body.
[0006] In some possible implementations, the pusher assembly includes a pusher portion and a drive portion, wherein: The pushing portion is used to push the silicon carbide powder in the crucible body; The driving part is used to drive the pushing part to move in the radial direction of the crucible body.
[0007] In some possible implementations, the surface of the pushing portion for pushing the silicon carbide powder is arc-shaped.
[0008] In some possible implementations, the surface of the pushing portion for pushing the silicon carbide powder has the same curvature as the inner surface of the crucible body.
[0009] In some possible implementations, the surface of the pusher portion for pushing the silicon carbide powder is made of graphite.
[0010] In some possible implementations, the pushing portion is located at the center of the crucible in the height direction of the crucible.
[0011] In some possible implementations, the driving part is a cylinder.
[0012] In some possible implementations, the pusher assembly further includes a connecting piece, which is used to connect the pusher portion and the driving portion, so that the driving portion drives the connecting piece to extend and retract to make the pusher portion reciprocate in the radial direction of the crucible body.
[0013] In a second aspect, the present disclosure provides an apparatus for growing a silicon carbide crystal, the apparatus comprising the crucible for growing a silicon carbide crystal according to the first aspect.
[0014] In a third aspect, the present disclosure provides a method for growing silicon carbide crystals, which can be applied to the apparatus for growing silicon carbide crystals described in the second aspect, and the method grows silicon carbide crystals by physical vapor transport.
[0015] The present disclosure provides a crucible, device and method for growing silicon carbide crystals. A pusher assembly is arranged in the crucible body, and the pusher assembly can move in the radial direction of the crucible body during the growth of silicon carbide crystals to push silicon carbide powder in the central area of the crucible body to the edge area of the crucible body, thereby making the heat absorbed by silicon carbide powder in different areas of the crucible body more uniform, so as to adjust the temperature gradient in the crucible, thereby improving the graphitization phenomenon occurring during the growth of silicon carbide crystals, reducing the generation of carbon particles, and improving the growth efficiency and quality of silicon carbide crystals. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the structure of an apparatus for growing silicon carbide crystals in the related art.
[0017] Figure 2 To use Figure 1 The device for growing silicon carbide crystals is shown as a schematic diagram of graphitization of silicon carbide powder during the process of growing silicon carbide crystals.
[0018] Figure 3 To use Figure 1 Another schematic diagram of the apparatus for growing silicon carbide crystals is shown, showing graphitization of silicon carbide powder during the process of growing silicon carbide crystals.
[0019] Figure 4 To use Figure 1 The device for growing silicon carbide crystals is shown as another schematic diagram of graphitization of silicon carbide powder during the process of growing silicon carbide crystals.
[0020] Figure 5 A schematic diagram of the structure of a crucible for growing silicon carbide crystals provided by the present invention.
[0021] Figure 6 Schematic diagram of the central area and edge area of the crucible body provided by the present disclosure.
[0022] Figure 7 The present disclosure provides Figure 5 A cross-sectional view along section line BB is shown in FIG.
[0023] Figure 8 A schematic diagram of the structure of an apparatus for growing silicon carbide crystals provided in the present invention.
[0024] Fig. 9 For separate use Figure 1 Equipment for growing silicon carbide crystals and Figure 8 A schematic diagram of the relationship between the C / Si ratio on the surface of the silicon carbide powder on the central axis of the crucible body and time when the silicon carbide crystal is grown in the device for growing silicon carbide crystal. DETAILED DESCRIPTION
[0025] The technical solutions in the present disclosure will be described clearly and completely below in conjunction with the accompanying drawings in the present disclosure.
[0026] It should be noted that, for the sake of clarity, not all features of a specific implementation are described and illustrated in the specification and drawings. Furthermore, in order to avoid unnecessary details that obscure the technical solution focused on by the present disclosure, only the device structures and parts closely related to the technical solution of the present disclosure are described and illustrated in the specification and drawings, while other details that are not closely related to the technical content of the present disclosure and are known to those skilled in the art are omitted.
[0027] See also Figure 1, which shows an apparatus 1A for growing silicon carbide crystals in the related art. The apparatus 1A specifically includes a furnace body 10 , a crucible 20A, a heater 30 , and a graphite filter plate 40 .
[0028] Specifically, the crucible 20A includes a crucible body 201 and a crucible cover 202 disposed on the crucible body 201. In a specific implementation, silicon carbide powder 50 for growing silicon carbide crystals is placed at the bottom of the crucible body 201, and silicon carbide seed crystals 60 are fixed on the crucible cover 202.
[0029] In some examples, the crucible 20A is made of graphite.
[0030] Heater 30 is provided outside crucible 20A and is used to sublime silicon carbide powder 50 by heating crucible 20A.
[0031] The graphite filter plate 40 is disposed at the middle position of the inner side of the crucible 20A to prevent the carbon particles formed during the growth of the silicon carbide crystal from being transported by the gas phase to the surface of the formed silicon carbide crystal.
[0032] In the specific implementation process, after the silicon carbide powder 50 is placed at the bottom of the crucible body 201 and the silicon carbide seed crystal 60 is fixed to the crucible cover 202, the crucible 20A is heated by the heater 30. It can be understood that the heat is thermally conducted to the silicon carbide powder 50 via the crucible 20A. Then, the silicon carbide powder 50 absorbs the heat, sublimates and decomposes, and forms a gas phase substance containing Si component and C component. These gas phase substances are transported to the silicon carbide seed crystal 60 with a relatively low temperature driven by the temperature gradient. When these gas phase substances reach the surface of the silicon carbide seed crystal 60, the Si component and C component in the supersaturated state recrystallize to form silicon carbide crystals on the surface of the silicon carbide seed crystal 60.
[0033] However, during the growth of the silicon carbide crystal, since heat is transferred to the silicon carbide powder 50 via the crucible 20A, the temperature of the edge region near the crucible body 201 is higher than the temperature of the central region, and the temperature of the central region of the crucible body 201 is higher than the temperature of the upper region, thereby forming a temperature gradient in the axial direction and radial direction of the crucible 20A. Figure 2 As shown, under the influence of the temperature gradient, the silicon carbide powder 50 in the bottom area and the edge area of the crucible body 201 undergoes graphitization to form carbon particles 70, and as the silicon carbide crystals grow, as shown in FIG. Figure 3 and Figure 4 As shown in FIG. 1 , the content of these carbon particles 70 will increase. On the one hand, these carbon particles 70 will be transported to the silicon carbide seed crystal 60 under the action of the temperature gradient, such as Figure 2As shown by the dotted arrow in . Although a graphite filter plate 40 is provided in the middle of the crucible 20A, when too much carbon particles 70 accumulate, the transport channel on the graphite filter plate 40 may be blocked, hindering the timely transport of the above-mentioned gas phase substances containing Si components and C components to the silicon carbide seed crystal 60. On the other hand, these carbon particles 70 will also increase the porosity of the silicon carbide powder 50 in the bottom area and the edge area of the crucible body 201, thereby affecting the sublimation process of the silicon carbide powder 50, thereby affecting the timely supply of the gas phase substances containing Si components and C components, and finally affecting the growth of silicon carbide crystals.
[0034] Based on the above description, the present disclosure is expected to provide a method for improving the graphitization phenomenon by changing the flow state of the silicon carbide powder 50 in the crucible body 201, thereby improving the growth efficiency and quality of the silicon carbide crystal. Figure 5 , which shows a crucible 20 for growing silicon carbide crystals provided by the present disclosure, the crucible comprising: a cylindrical crucible body 201 and a pusher assembly 203. Among them, The crucible body 201 is used to contain silicon carbide powder; and The pusher assembly 203 is disposed in the crucible body 201 , and can move along the radial direction of the crucible body 201 during the growth of silicon carbide crystals to push silicon carbide powder in the central area of the crucible body 201 to the edge area of the crucible body 201 .
[0035] In some examples, the edge region of the crucible body 201 refers to a region close to the inner wall of the crucible body 201 in the radial direction of the crucible body 201, such as Figure 6 The central area refers to the area close to the center position of the crucible body 201 in the radial direction of the crucible body 201, as shown in FIG. Figure 6 As shown in the left-slash filled area.
[0036] It can be understood that the pusher assembly 203 is provided in the crucible body 201 to adjust the flow state of the silicon carbide powder 50 in the crucible body 201 to promote the growth of silicon carbide crystals. Specifically, when the silicon carbide powder 50 in the crucible body 201 is heated by the heater 30, the pusher assembly 203 is used to push the silicon carbide powder 50 in the central area of the crucible body 201 to the edge area of the crucible body 201. Figure 5 The direction indicated by the solid arrow shown in the figure helps the silicon carbide powder 50 in different areas of the crucible body 201 to absorb heat more evenly, so as to adjust the temperature gradient in the crucible 20, thereby improving the above-mentioned graphitization phenomenon, reducing the generation of carbon particles, and improving the utilization rate of the silicon carbide powder.
[0037] In addition, under the action of the pushing part 2031, the silicon carbide powder 50 in the central area of the crucible body 201 is pushed to the edge area to fill the pores in the edge area caused by graphitization, so that the porosity of the silicon carbide powder 50 in the crucible body 201 is maintained, thereby improving the sublimation efficiency and utilization rate of the silicon carbide powder 50.
[0038] Of course, in some examples, due to the reduction of graphitization and the generation of carbon particles, the C / Si ratio during the growth of silicon carbide crystals can be improved, which helps to reduce the occurrence of phase change during the growth of silicon carbide crystals, thereby improving the growth quality of silicon carbide crystals. It should be noted that the above C / Si ratio refers to the ratio of the C component to the Si component during the growth of silicon carbide crystals.
[0039] It should be pointed out that although Figure 5 2 shows that two pusher assemblies 203 are provided in the crucible body 201, but in the specific implementation process, multiple pusher assemblies 203 can be provided according to the characteristics of gas phase transport and the specific growth requirements of silicon carbide crystals. For example, three pusher assemblies 203 or four pusher assemblies 203 can be installed to more thoroughly realize the exchange and mixing of silicon carbide powder 50 in the central area of the crucible body 201 and silicon carbide powder 50 in the edge area, further promote the uniform distribution of heat, and provide more positive conditions for the growth of silicon carbide crystals.
[0040] With regard to the technical solution disclosed in the present invention, a pushing assembly 203 is arranged in the crucible body 201, and the pushing assembly 203 can move along the radial direction of the crucible body 201 during the growth of silicon carbide crystals, so as to push the silicon carbide powder in the central area of the crucible body 201 to the edge area of the crucible body 201, thereby making it possible for the silicon carbide powder in different areas of the crucible body 201 to absorb heat more evenly, so as to adjust the temperature gradient in the crucible 20, thereby improving the above-mentioned graphitization phenomenon, reducing the generation of carbon particles, and improving the growth efficiency and quality of silicon carbide crystals.
[0041] for Figure 5 In some possible implementations of the technical solution shown, Figure 5 As shown, the pusher assembly 203 includes a pusher portion 2031 and a drive portion 2032, wherein: The pushing portion 2031 is used to push the silicon carbide powder 50 in the crucible body 201; The driving portion 2032 is used to drive the pushing portion 2031 to move in the radial direction of the crucible body 201 .
[0042] In this case, the distribution of the silicon carbide powder 50 in the crucible body 201 can be accurately adjusted through the pushing portion 2031 to ensure that the silicon carbide powder 50 is evenly distributed in the crucible 20, which is crucial for maintaining temperature uniformity during the growth process. This can reduce the graphitization phenomenon in the high-temperature area near the inner wall of the crucible 20, reduce the formation of carbon particles, thereby reducing the blockage of the gas phase transmission channel and improving the growth quality of silicon carbide crystals.
[0043] In addition, by driving the pusher 2031 along the radial direction of the crucible body 201 , the silicon carbide powder 50 in the central area of the crucible body 201 is pushed toward the edge area of the crucible body 201 , so as to improve the sublimation rate of the silicon carbide powder 50 and the growth efficiency of the silicon carbide crystals.
[0044] In summary, by continuously pushing the silicon carbide powder 50 by the pushing assembly 203 , it is possible to ensure that the silicon carbide powder 50 contained in the crucible body 201 participates in the silicon carbide crystal growth process to the greatest extent, thereby improving the utilization rate of the silicon carbide powder 50 .
[0045] For the above implementations, in some examples, such as Figure 7 As shown, the surface 20311 of the pushing portion 2031 for pushing the silicon carbide powder 50 is arc-shaped.
[0046] It should be noted that Figure 7 For along Figure 5 A cross-sectional view along section line BB is shown in FIG.
[0047] It can be understood that in the present disclosure, setting the surface 20311 of the pushing portion 2031 for pushing the silicon carbide powder 50 into an arc shape can better adapt to the shape of the inner surface of the crucible body 201, so as to push the silicon carbide powder 50 more evenly during the pushing process, avoid accumulation or uneven distribution of the silicon carbide powder 50 during the pushing process, thereby helping to maintain the temperature gradient distribution during the growth of the silicon carbide crystal.
[0048] In addition, the surface 20311 of the pushing portion 2031 for pushing the silicon carbide powder 50 is set to an arc shape, which helps to improve the fluidity of the silicon carbide powder 50 during the pushing process, effectively reducing the accumulation of the silicon carbide powder 50 in the dead corner area of the crucible 20, and avoiding the problem of local overheating or graphitization caused by it. This design can reduce the stagnation of the silicon carbide powder 50 in the crucible 20, thereby improving the sublimation efficiency of the silicon carbide powder 50.
[0049] In some examples, the surface 20311 of the pushing portion 2031 for pushing the silicon carbide powder 50 and the inner surface 2011 of the crucible body 201 have the same curvature.
[0050] This is because the surface 20311 of the pusher 2031 for pushing the silicon carbide powder 50 has the same curvature as the inner surface 2011 of the crucible body 201, which helps to reduce the resistance of the silicon carbide powder 50 during the pushing process and improve the fluidity of the silicon carbide powder 50. In addition, since the pushing surface 20311 of the pusher 2031 has the same curvature as the inner surface of the crucible body 201, the silicon carbide powder 50 can be pushed more evenly, so that the heat distribution in the crucible 20 is more even during the growth of silicon carbide crystals, local high temperature areas are reduced, and the risk of graphitization is reduced.
[0051] For the above-mentioned embodiments, in some examples, the surface 20311 of the pushing portion 2031 for pushing the silicon carbide powder 50 is made of graphite.
[0052] This is because graphite has good chemical stability at high temperatures and is not prone to chemical reactions when in contact with the silicon carbide powder 50 , thus ensuring the stability of the chemical environment during the growth of the silicon carbide crystals and avoiding the introduction of unnecessary impurities.
[0053] In addition, graphite has a moderate hardness. As the material of the pusher part 2031 , it can maintain a low wear rate during long-term contact and friction with the silicon carbide powder 50 , thereby extending the service life of the pusher part 2031 .
[0054] For the above-mentioned embodiments, in some examples, the pushing portion 2031 is located at the center of the crucible body 201 in the height direction of the crucible body 201 .
[0055] It can be understood that in this case, the pusher 2031 is located at the center of the crucible body 201, which can change the flow state of the silicon carbide powder 50 in the crucible body 201 to the greatest extent. This is because this design allows the pusher 2031 to change the flow state of the silicon carbide powder 50 in the central area of the crucible body 201 to the greatest extent, thereby achieving the mixing of the silicon carbide powder 50 in the central area with the silicon carbide powder 50 in the edge area, optimizing the distribution of the silicon carbide powder 50 in the crucible body 201, reducing the risk of local overheating or graphitization, and improving its sublimation efficiency, thereby improving the utilization rate of the silicon carbide powder 50 and the growth quality of silicon carbide crystals.
[0056] For the above-mentioned embodiments, in some examples, the driving part 2032 is a cylinder.
[0057] It is understandable that the cylinder uses compressed air as a power source to quickly generate linear motion. Therefore, in the present disclosure, by setting the driving part 2032 as a cylinder to push the movement of the pusher part 2031, the driving force and stroke of the pusher part 2031 can be accurately controlled, so that the movement of the pusher part 2031 can be adjusted according to the specific growth process, and the flow state and distribution of the silicon carbide powder 50 can be optimized.
[0058] For the above implementations, in some examples, such as Figure 7 As shown, the pusher assembly 203 further includes a connector 2033 for connecting the pusher portion 2031 and the driving portion 2032 , so that the driving portion 2032 drives the connector 2033 to extend and retract to allow the pusher portion 2031 to reciprocate in the radial direction of the crucible body 201 .
[0059] In the present disclosure, the connecting member 2033 acts as an intermediary between the pusher 2031 and the driving member 2032, and can ensure that the power generated by the driving member 2032 is accurately transmitted from the driving member 2032 to the pusher 2031, thereby realizing accurate control of the movement of the pusher 2031. In addition, the pusher 2031 can achieve reciprocating movement through the extension and contraction of the connecting member 2033. This design provides flexible movement control, and in the specific implementation process, the position and movement distance of the pusher 2031 can be adjusted according to the actual needs of the growth process of the silicon carbide crystal.
[0060] In addition, if Figure 8 As shown, the present disclosure provides a device 1 for growing silicon carbide crystals, and the device 1 includes a crucible 20 for growing silicon carbide crystals according to the aforementioned technical solution.
[0061] Finally, the present disclosure also provides a method for growing silicon carbide crystals, which can be applied to the device 1 for growing silicon carbide crystals described in the aforementioned technical solution, and the method grows silicon carbide crystals by physical vapor transport.
[0062] like Fig. 9 As shown, it shows a schematic diagram of the relationship between the C / Si ratio of the silicon carbide powder surface on the central axis of the crucible body 201 and time when growing silicon carbide crystals using the device 1A for growing silicon carbide crystals in the related art and the device 1 for growing silicon carbide crystals provided by the present disclosure. Among them, Fig. 9 The solid line in is a schematic diagram showing the relationship between the C / Si ratio of the surface of the silicon carbide powder on the central axis of the crucible body 201 and time when the silicon carbide crystal is grown using the apparatus 1A for growing silicon carbide crystal in the related art. Fig. 9The dotted line in FIG. 1 is a schematic diagram showing the relationship between the C / Si ratio of the silicon carbide powder surface on the central axis of the crucible body 201 and time when the silicon carbide crystal growth device 1 provided by the present disclosure is used to grow silicon carbide crystals. Fig. 9 It can be seen that when growing silicon carbide crystals, the device 1 for growing silicon carbide crystals provided by the present disclosure can increase the C / Si ratio of the silicon carbide powder surface on the central axis of the crucible body 201, thereby reducing the occurrence of phase change and improving the growth quality of silicon carbide crystals.
[0063] It should be noted that the technical solutions described in the present disclosure can be combined arbitrarily without conflict.
[0064] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.
Claims
1. A crucible for growing silicon carbide crystals, characterized in that: The crucible comprises: a cylindrical crucible body, wherein the crucible body is used to contain silicon carbide powder; and A pusher assembly is disposed in the crucible body and can move along the radial direction of the crucible body during the growth of silicon carbide crystals to push silicon carbide powder in the central area of the crucible body to the edge area of the crucible body.
2. The crucible for growing silicon carbide crystals according to claim 1, characterized in that: The pusher assembly includes a pusher part and a driving part, wherein: The pushing portion is used to push the silicon carbide powder in the crucible body; The driving part is used to drive the pushing part to move in the radial direction of the crucible body.
3. The crucible for growing silicon carbide crystals according to claim 2, characterized in that: The surface of the pushing portion for pushing the silicon carbide powder is arc-shaped.
4. The crucible for growing silicon carbide crystals according to claim 3, characterized in that: The surface of the pushing portion for pushing the silicon carbide powder has the same curvature as the inner surface of the crucible body.
5. The crucible for growing silicon carbide crystals according to claim 2, characterized in that: The material of the surface of the pusher part for pushing the silicon carbide powder is graphite.
6. The crucible for growing silicon carbide crystals according to claim 2, characterized in that: The pushing portion is located at the center of the crucible in the height direction of the crucible.
7. The crucible for growing silicon carbide crystals according to claim 2, characterized in that: The driving part is a cylinder.
8. The crucible for growing silicon carbide crystals according to claim 2, characterized in that: The pusher assembly further includes a connecting piece, which is used to connect the pusher portion and the driving portion, so that the driving portion drives the connecting piece to extend and retract to make the pusher portion reciprocate in the radial direction of the crucible body.
9. An apparatus for growing silicon carbide crystals, characterized in that: The apparatus comprises a crucible for silicon carbide crystal growth according to any one of claims 1 to 8.
10. A method for growing silicon carbide crystals, characterized in that: The method can be applied to the apparatus for growing silicon carbide crystal according to claim 9, and the method grows silicon carbide crystal by a physical vapor transport method.