Method and device for growing silicon carbide crystals
By setting a seed crystal rack and a tantalum carbide back plate on the surface of silicon carbide powder, controlling the temperature gradient and seed crystal angle, and optimizing the structure of the crystal growth device, the problem of surface crystallization of silicon carbide powder affecting the sublimation of the powder was solved, and efficient utilization of the powder and improvement of the crystal yield were achieved.
Patent Information
- Application Number
- CN202510878895.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-09-16
AI Technical Summary
In the prior art, during the growth of silicon carbide crystals, surface crystallization of silicon carbide powder affects powder sublimation and crystal growth, resulting in reduced powder utilization and crystal yield.
By setting a seed crystal rack and a tantalum carbide back plate on the surface of silicon carbide powder, controlling the temperature gradient and seed crystal angle, and optimizing the structure of the crystal growth device, including the porous tantalum carbide back plate assembly, the effective utilization of the gas phase powder is ensured.
The utilization rate of silicon carbide powder and the crystal yield are improved, the output and quality of crystals are increased, and powder waste is avoided.
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Figure CN120649144A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of crystal growth, and in particular to a method and device for growing silicon carbide crystals. Background Art
[0002] In the prior art, when the sublimated gas phase of silicon carbide powder reaches the boundary of the growth chamber—that is, the surface of the silicon carbide powder—during the silicon carbide crystal growth process, the interface temperature decreases, resulting in the formation of numerous crystals on the surface of the silicon carbide powder. This polycrystal formation not only affects subsequent sublimation of the powder but also hinders the growth of crystals at the top of the crucible. Crystals on the surface of the silicon carbide powder cannot be directly sold as a product, reducing the utilization rate of the powder and the yield of the crystals.
[0003] In view of this, the present invention is proposed. Summary of the Invention
[0004] The present invention aims to provide a method and apparatus for growing silicon carbide crystals. Embodiments of the present invention provide a method for growing silicon carbide crystals that allows the material crystallized on the surface of silicon carbide powder to grow normally to obtain the desired single crystal or polycrystal, thereby improving the utilization rate of the powder and the yield of the crystals.
[0005] The present invention is achieved in that: In a first aspect, the present invention provides a method for growing silicon carbide crystals, comprising: setting the surface temperature of silicon carbide powder to 2000-2400°C; The temperature at the top of the crystal growth zone is reduced to 1800-2300℃; The temperature setting during the crystal growth process is as follows: at the initial stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 50-200°C; In the middle stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 50-100° C.; At the late stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 0-50°C.
[0006] In an optional embodiment, the first seed crystal is placed at an angle of C-axis offset. <1120> Direction 0-4 o , preferably 1 o .
[0007] In an optional embodiment, the temperature of the surface of the silicon carbide powder in the middle and late growth stages is higher than the temperature of the surface of the silicon carbide powder in the early growth stage.
[0008] In a second aspect, the present invention provides a silicon carbide crystal growth apparatus, wherein the silicon carbide crystal growth apparatus is used to implement the silicon carbide crystal growth method described in any one of the aforementioned embodiments; The invention comprises: a crucible, a seed crystal rack with air holes, a plurality of tantalum carbide back plates and a plurality of first seed crystals. The seed crystal rack is arranged in the crucible and on the silicon carbide powder. The plurality of tantalum carbide back plates are respectively arranged on the seed crystal rack and connected to the seed crystal rack. The plurality of first seed crystals are respectively arranged on one side of the plurality of tantalum carbide back plates and connected to the seed crystal rack.
[0009] In an optional embodiment, the distance between two adjacent tantalum carbide back plates is 20-50 mm; Preferably, the plurality of tantalum carbide back plates are arranged along a radial direction.
[0010] In an optional embodiment, the distance between the seed rack and the surface of the silicon carbide powder is 0-0.3 times the crystal diameter.
[0011] In an optional embodiment, the crystal growth device also includes a porous tantalum carbide backplate assembly with pores, the porous tantalum carbide backplate assembly is arranged in the crucible and connected to the crucible, and the porous tantalum carbide backplate is arranged on a side of the tantalum carbide backplate relatively away from the seed crystal rack.
[0012] In an optional embodiment, the porous tantalum carbide backplate assembly includes at least two porous tantalum carbide backplates, at least two of the porous tantalum carbide backplates are arranged in the axial direction and are both arranged on a side of the tantalum carbide backplate relatively away from the seed crystal rack, and the pores of the two porous tantalum carbide backplates are staggered.
[0013] In an optional embodiment, the distance between the two porous tantalum carbide back plates is 0.5-0.8 times the crystal diameter; Preferably, tantalum carbide particles are provided between the two porous tantalum carbide back plates; Preferably, the stacking thickness of the tantalum carbide particles is 2-5 mm.
[0014] In an optional embodiment, a second seed crystal is disposed on the top of the crucible.
[0015] The present invention has the following beneficial effects: An embodiment of the present invention provides a crystal growth method that, by disposing a seed crystal rack and a first seed crystal on the surface of existing silicon carbide powder, enables direct crystal growth of vapor-phase powder that reaches the surface of the silicon carbide powder, thereby fully utilizing the vapor-phase powder that reaches the surface of the silicon carbide powder and improving powder utilization. Furthermore, the vapor-phase powder continues to grow at the top of the crucible to obtain the desired crystals, further improving the crystal yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.
[0017] Figure 1 A schematic structural diagram of a silicon carbide crystal growth apparatus provided in an embodiment of the present invention; Figure 2 A schematic diagram of the positions of the first graphite sheet and the second graphite sheet provided in an embodiment of the present invention; Figure 3 This is a schematic structural diagram of the crucible provided in Comparative Example 1 of the present invention.
[0018] Icons: 100-silicon carbide crystal growth device; 110-crucible; 120-silicon carbide powder; 121-first graphite sheet; 130-seed crystal rack; 131-pores; 140-first seed crystal; 150-tantalum carbide back plate; 160-porous tantalum carbide back plate assembly; 161-porous tantalum carbide back plate; 170-second graphite sheet; 180-second seed crystal. DETAILED DESCRIPTION
[0019] 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 are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.
[0020] An embodiment of the present invention provides a method for growing silicon carbide crystals, comprising: setting the surface temperature of silicon carbide powder to 2000-2400°C; for example, any value between 2000-2400°C, such as 2000°C, 2100°C, 2200°C, 2300°C or 2400°C.
[0021] Specifically, the temperature of the lowest part of the crystal growth area in the crucible is 2000-2400° C., and the temperature of the top of the crystal growth area is 1800-2300° C. The above temperatures are conducive to crystal growth and the desired crystals can be obtained.
[0022] Specifically, the temperature setting during the crystal growth process is as follows: In the initial growth phase, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the growth zone is 50-200°C; for example, any value between 50°C, 100°C, 150°C, or 200°C is selected to promote vertical growth of the seed crystal. However, the overall temperature should be low to prevent abrupt temperature changes at the seed crystal shelf, resulting in excessive growth and damage to the seed crystal structure.
[0023] In the middle of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the growth zone is 50-100° C.; the above temperature gradient is used to ensure that the seed rack and the top seed crystal maintain stable growth.
[0024] In the later stages of growth, the temperature gradient between the surface of the silicon carbide powder and the top of the growth zone is 0-50° C. This temperature gradient is used to slow the horizontal growth of the seed rack crystals, promote recrystallization of the crystals on the seed rack to improve crystal quality, and avoid blocking the airway and affecting the growth of the top crystals.
[0025] Furthermore, the surface temperature of the silicon carbide powder in the middle and late growth stages is higher than the surface temperature of the silicon carbide powder in the early growth stages, thereby increasing the sublimation amount of the powder and promoting the growth of crystals at various locations.
[0026] Furthermore, the first seed crystal is placed at an angle of C-axis offset. <1120> Direction 0-4 o , preferably 1 o The seed crystal is arranged on the seed crystal rack in the above manner and then provides a small number of steps to prevent the crystal from growing too fast in the horizontal direction, thereby reducing the wafer quality and blocking the air flow channel, thereby achieving the purpose of reducing defects such as phase change and dislocation.
[0027] In summary, the crystal growth method provided by the embodiment of the present invention can enable the vapor phase powder to form crystals along the surface of the silicon carbide powder, thereby improving the utilization rate of the powder and increasing the yield of crystals.
[0028] The features and performance of the present invention are further described in detail below with reference to the embodiments.
[0029] Example 1 See also Figure 1 An embodiment of the present invention provides a silicon carbide crystal growth device 100 , which includes a crucible 110 . The crucible 110 provides necessary space for crystal growth.
[0030] It should be noted that the shape and size of the crucible 110 are not limited and can be an oval or square crucible, or placed inside a round crucible.
[0031] Furthermore, silicon carbide powder 120 is placed in the crucible 110 , and a seed rack 130 is placed on the silicon carbide powder 120 . The seed rack 130 can be placed directly on the silicon carbide powder 120 .
[0032] It is understood that the seed rack 130 can be spaced a certain distance from the surface of the silicon carbide powder 120 while the seed rack 130 is connected to the crucible 110. Furthermore, the distance between the seed rack 130 and the surface of the silicon carbide powder 120 is less than 0.3 times the crystal diameter, which facilitates subsequent crystal growth. Furthermore, the silicon carbide powder 120 does not necessarily fill the top of the powder zone.
[0033] The crucible 110 also includes a plurality of first graphite sheets 121 for measuring the surface temperature of the silicon carbide powder 120. Specifically, the plurality of first graphite sheets 121 are disposed outside the crucible 110 and arranged in a circular pattern along the circumference of the crucible 110. Furthermore, the first graphite sheets 121 are positioned on the silicon carbide powder 120. The surface temperature of the silicon carbide powder 120 can be determined by measuring the temperatures of the plurality of first graphite sheets 121 and then taking the average value.
[0034] Furthermore, the seed crystal rack 130 is provided with air holes 131 to provide a stable air flow for the growth of the first seed crystal 140. The seed crystal rack 130 is made of graphite.
[0035] Specifically, the seed crystal rack 130 is provided with a first seed crystal 140, and the first seed crystal 140 is determined according to the crystal to be grown. <1120> Direction 0-4 o , preferably 1 o , providing a small number of steps to prevent the product from growing too fast in the horizontal direction, which may reduce the quality of the product and block the air flow channel, thereby achieving the purpose of reducing defects such as phase change and dislocation.
[0036] Furthermore, the system further includes a plurality of tantalum carbide back plates 150, each of which is disposed on and connected to the seed crystal rack 130. The plurality of first seed crystals 140 are disposed one-to-one on one side of the plurality of tantalum carbide back plates 150 and connected to the seed crystal rack 130. In other words, the tantalum carbide back plates 150 are disposed in a non-porous area of the seed crystal rack 130, and the first seed crystals 140 are bonded to the tantalum carbide back plates, thereby facilitating crystal growth.
[0037] Preferably, first seed crystals 140 are provided on both sides of the tantalum carbide back plate 150 located in the middle of the crucible 110 , so that the crystals on both sides of the tantalum carbide back plate 150 in the middle portion grow symmetrically, which can further improve the crystal yield.
[0038] Furthermore, the distance between two adjacent tantalum carbide back plates 150 is 20-50 mm, which is conducive to gas phase diffusion, crystallization and crystal growth, ensuring the quality of the formed crystal. The length of the tantalum carbide back plate 150 is determined according to the specifications of the prepared crystal.
[0039] Furthermore, a plurality of tantalum carbide back plates 150 are arranged in a radial direction. Each tantalum carbide back plate is adhered with a first seed crystal 140, thereby further improving the yield of the crystal.
[0040] Furthermore, the crystal growth apparatus further includes a porous tantalum carbide back plate assembly 160 with pores 131. The porous tantalum carbide back plate assembly 160 is disposed in and connected to the crucible 110. The porous tantalum carbide back plate 161 is disposed on a side of the tantalum carbide back plate 150 relatively away from the seed crystal rack 130, that is, the porous tantalum carbide back plate assembly 160 is disposed on top of the tantalum carbide back plate 150. Specifically, the distance between the porous tantalum carbide back plate assembly 160 and the top of the tantalum carbide back plate 150 is 0.3-1.2 times the crystal diameter.
[0041] Specifically, the porous tantalum carbide back plate assembly 160 includes at least two porous tantalum carbide back plates 161, and at least two of the porous tantalum carbide back plates 161 are arranged in the axial direction. The distance between the two porous tantalum carbide back plates 161 is 0.5-0.8 times the crystal diameter to ensure the diffusion of the gas phase.
[0042] Furthermore, the pores 131 of the two porous tantalum carbide back plates 161 are staggered to redistribute the airflow into a normal distribution state to facilitate normal growth of the top crystal.
[0043] Tantalum carbide particles are arranged between the two porous tantalum carbide back plates 161; and the stacking thickness of the tantalum carbide particles is 2-5 mm. The arrangement of tantalum carbide particles and the stacking thickness are more conducive to the redistribution of airflow to form a normal distribution.
[0044] Further, see Figure 2 , further comprising a plurality of second graphite sheets 170. The second graphite sheets 170 are disposed outside and connected to the crucible 110, and are arranged in a ring around the crucible 110. Furthermore, the second graphite sheet 170 is disposed on the side of the porous tantalum carbide backing plate 161 that is farther from the top of the crucible 110 than the two porous tantalum carbide backing plates 161. The temperatures of the plurality of second graphite sheets 170 are then measured and averaged to determine the temperature at the top of the crystal growth zone. The plurality of first graphite sheets 121 and the plurality of second graphite sheets 170 are spaced apart.
[0045] Furthermore, a second seed crystal 180 is disposed on the top of the crucible 110 , so that the crystal on the top can grow normally.
[0046] Example 2 An embodiment of the present invention provides a method for growing a silicon carbide crystal. The method uses the silicon carbide crystal growth apparatus provided in Example 1 to grow the crystal. At this time, the seed rack 130 can be at a distance of 0.1 times the crystal diameter from the surface of the silicon carbide powder 120. Specifically, the method includes: Specifically, the temperature settings during the crystal growth process are as follows: at the initial growth stage, the temperature of the surface of the silicon carbide powder is 2080°C; and the temperature of the top of the crystal growth zone is 1935°C.
[0047] In the middle stage of growth, the temperature of the surface of the silicon carbide powder is 2176°C; the temperature of the top of the growth zone is 2103°C; At the late stage of growth, the temperature of the surface of the silicon carbide powder is 2245°C; and the temperature of the top of the crystal growth zone is 2208°C.
[0048] The first seed crystal is placed at an angle of C-axis offset. <1120> Direction 0.5 o The second seed crystal disposed on the top of the crucible 110 is placed at an angle of C-axis deviation. <1120> Direction 4 o .
[0049] The mass of the desired silicon carbide crystal formed on the top of the crucible 110 is 1948 g, the total mass of the desired crystal formed on the seed crystal rack is 623 g, and the mass of the polycrystal formed on the powder pile is 121 g.
[0050] Example 3 An embodiment of the present invention provides a method for growing a silicon carbide crystal. The method uses the silicon carbide crystal growth apparatus provided in Example 1 to grow the crystal. In this case, a seed rack 130 is directly placed on the silicon carbide powder 120. The method specifically includes: Specifically, the temperature settings during the crystal growth process are as follows: at the initial stage of growth, the temperature of the surface of the silicon carbide powder is 2066°C; the temperature of the top of the crystal growth zone is 1938°C; In the middle stage of growth, the temperature of the surface of the silicon carbide powder is 2191°C; the temperature of the top of the growth zone is 2122°C; At the late stage of growth, the temperature of the surface of the silicon carbide powder is 2220°C; and the temperature of the top of the crystal growth zone is 2203°C.
[0051] The first seed crystal is placed at an angle of C-axis offset. <1120> Direction 1 o The second seed crystal disposed on the top of the crucible 110 is placed at an angle of C-axis deviation. <1120> 4 o .
[0052] The mass of the desired silicon carbide crystal formed on the top of the crucible 110 is 1738 g, the total mass of the desired crystal formed on the seed crystal rack is 404 g, and the mass of the polycrystal formed on the powder pile is 86 g.
[0053] Example 4 An embodiment of the present invention provides a method for growing a silicon carbide crystal. The method uses the silicon carbide crystal growth apparatus provided in Example 1 to grow the crystal. At this time, the seed rack 130 can be at a distance of 0.2 times the crystal diameter from the surface of the silicon carbide powder 120. Specifically, the method includes: Specifically, the temperature settings during the crystal growth process are as follows: at the initial stage of growth, the temperature of the surface of the silicon carbide powder is 2086°C; the temperature of the top of the crystal growth zone is 1924°C; In the middle stage of growth, the temperature of the surface of the silicon carbide powder is 2198°C; the temperature of the top of the growth zone is 2141°C; At the late growth stage, the temperature of the surface of the silicon carbide powder was 2236°C; and the temperature at the top of the crystal growth zone was 2224°C.
[0054] The first seed crystal is placed at an angle of C-axis offset. <1120> Direction 0 o The second seed crystal disposed on the top of the crucible 110 is placed at an angle of C-axis deviation. <1120> Direction 4 o .
[0055] The mass of the desired silicon carbide crystal formed on the top of the crucible 110 is 2023 g, the total mass of the desired crystal formed on the seed crystal rack is 434 g, and the mass of the polycrystal formed on the powder pile is 107 g.
[0056] Comparative Example 1 Comparative Example 1 provides a method for growing silicon carbide crystals. The method uses a conventional crucible, the structure of which is shown in FIG. Figure 3 Only the seed crystal is provided on the top of the crucible, and it is not provided with a seed crystal rack with air holes, multiple tantalum carbide back plates and a porous tantalum carbide back plate assembly.
[0057] The temperature setting in the crystal growth method provided in Comparative Example 1 is as follows: At the initial stage of growth, the temperature of the surface of the silicon carbide powder is 2207°C; the temperature of the top of the crystal growth zone is 2051°C; In the middle growth stage, the temperature of the surface of the silicon carbide powder is 2210°C; and the temperature of the top of the crystal growth zone is 2056°C.
[0058] At the late stage of growth, the temperature of the surface of the silicon carbide powder is 2215°C; and the temperature of the top of the crystal growth zone is 2061°C.
[0059] The second seed crystal is placed at the top of the crucible 110 at an angle of 4° from the C-axis, and no seed crystal is placed on the powder.
[0060] The mass of the desired silicon carbide crystal formed on the top of the crucible 110 was 1992 g, and the mass of the polycrystal formed on the powder pile was 577 g.
[0061] By comparing Example 3 with Comparative Example 1, it can be seen that the required amount of crystals obtained by using the silicon carbide crystal growth device provided by the embodiment of the present invention is significantly increased, and the amount of polycrystals formed on the powder pile is significantly reduced, indicating that it can improve the utilization rate of the powder and increase the yield of silicon carbide crystals.
[0062] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.
Claims
1. A method for growing silicon carbide crystals, characterized in that: include: Set the surface temperature of silicon carbide powder to 2000-2400℃; The temperature at the top of the crystal growth zone is reduced to 1800-2300℃; The temperature setting during the crystal growth process is as follows: at the initial stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 50-200°C; In the middle stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 50-100° C.; At the late stage of growth, the temperature gradient between the surface temperature of the silicon carbide powder and the temperature at the top of the crystal growth zone is 0-50°C.
2. The method for growing silicon carbide crystals according to claim 1, wherein: The first seed crystal is placed at an angle of C-axis offset. <1120> Direction 0-4 o , preferably 1 o .
3. The method for growing silicon carbide crystals according to claim 1 or 2, characterized in that: The temperature of the surface of the silicon carbide powder in the middle and late growth stages is higher than the temperature of the surface of the silicon carbide powder in the early growth stages.
4. A silicon carbide crystal growth device, characterized in that: The silicon carbide crystal growth device is used to implement the silicon carbide crystal growth method according to any one of claims 1 to 3; The invention comprises: a crucible, a seed crystal rack with air holes, a plurality of tantalum carbide back plates and a plurality of first seed crystals. The seed crystal rack is arranged in the crucible and on the silicon carbide powder. The plurality of tantalum carbide back plates are respectively arranged on the seed crystal rack and connected to the seed crystal rack. The plurality of first seed crystals are respectively arranged on one side of the plurality of tantalum carbide back plates and connected to the seed crystal rack.
5. The silicon carbide crystal growth device according to claim 4, characterized in that: The distance between two adjacent tantalum carbide back plates is 20-50 mm; Preferably, the plurality of tantalum carbide back plates are arranged along a radial direction.
6. The silicon carbide crystal growth device according to claim 4, characterized in that: The distance between the seed crystal rack and the surface of the silicon carbide powder is 0-0.3 times the crystal diameter.
7. The silicon carbide crystal growth device according to any one of claims 4 to 6, characterized in that: The crystal growth device also includes a porous tantalum carbide back plate assembly with pores, which is arranged in the crucible and connected to the crucible, and the porous tantalum carbide back plate is arranged on a side of the tantalum carbide back plate relatively away from the seed crystal rack.
8. The silicon carbide crystal growth device according to claim 7, characterized in that: The porous tantalum carbide backplate assembly includes at least two porous tantalum carbide backplates, at least two of the porous tantalum carbide backplates are arranged in the axial direction and are both arranged on a side of the tantalum carbide backplate relatively away from the seed crystal rack, and the pores of the two porous tantalum carbide backplates are staggered.
9. The silicon carbide crystal growth apparatus according to claim 7, characterized in that: The distance between the two porous tantalum carbide back plates is 0.5-0.8 times the crystal diameter; Preferably, tantalum carbide particles are provided between the two porous tantalum carbide back plates; Preferably, the stacking thickness of the tantalum carbide particles is 2-5 mm.
10. The silicon carbide crystal growth apparatus according to claim 7, characterized in that: A second seed crystal is arranged on the top of the crucible.