Silicon carbide seed crystal, silicon carbide crystal and forming method thereof
By using silicon carbide seed crystals composed of polycrystalline and single-crystalline silicon carbide layers, the thickness ratio is controlled and reused, the problems of high seed crystal cost and poor crystal growth quality are solved, and the low-cost growth of high-quality silicon carbide crystals is achieved.
Patent Information
- Application Number
- CN202510011201.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-01-10
- Filing Date
- 2025-01-03
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, the seed crystals of silicon carbide crystals have high seed crystal costs and poor crystal growth quality, making it difficult to simultaneously reduce seed crystal costs and improve crystal growth quality.
The first crystal layer including polycrystalline silicon carbide material and the second crystal layer of single crystal carbide material are used as the silicon carbide seed crystals, and the thickness ratio of the two is controlled to be within the range of 10% to 50%, and the silicon carbide crystal is formed by physical gas phase transport method, powder hot pressing method or chemical vapor deposition method, and the first crystal layer is reused for multiple crystal growth.
The high-quality growth of silicon carbide crystals is achieved, the seed crystal costs are reduced, and the competitiveness of the product is improved.
Smart Images
Figure CN120291209A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a silicon carbide seed crystal, and more particularly to a silicon carbide crystal and a method for forming a silicon carbide crystal using the silicon carbide seed crystal. Background Art
[0002] Silicon carbide (SiC) is a wide-band-gap semiconductor material. Silicon carbide has many remarkable physical properties, making it a major component for high-power, high-temperature, and high-frequency electronics today.
[0003] Silicon carbide crystals are generally grown using 6H silicon carbide or 4H silicon carbide as seed crystals. In the cost of silicon carbide crystal growth, the cost of the seed crystal occupies a large part. Therefore, if the cost of the seed crystal can be reduced and the quality of crystal growth can be improved at the same time, the competitiveness of the product will be greatly enhanced. Summary of the Invention
[0004] The present invention provides a silicon carbide seed crystal having a reusable seed crystal layer, and the silicon carbide crystal obtained by using the seed crystal for crystal growth process has better quality.
[0005] The silicon carbide seed crystal of the present invention includes a first seed crystal layer and a second seed crystal layer. The first seed crystal layer includes polycrystalline silicon carbide material. The second seed crystal layer is directly attached to the first seed crystal layer, wherein the second seed crystal layer includes single-crystalline silicon carbide material, and the thickness ratio (T2 / T1) of the thickness T1 of the first seed crystal layer to the thickness T2 of the second seed crystal layer is in the range of 10% to 50%.
[0006] In some embodiments, the thickness ratio (T2 / T1) is in the range of 30% to 50%.
[0007] In some embodiments, the polycrystalline silicon carbide material of the first seed crystal layer is formed by physical vapor transport process in the temperature range of 1900°C to 2300°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 1 mm to 20 mm.
[0008] In some embodiments, the polycrystalline silicon carbide material of the first seed crystal layer is formed by powder hot pressing process in the temperature range of 1800°C to 2100°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 1 µm to 500 µm.
[0009] In some embodiments, the polycrystalline silicon carbide material of the first crystal layer is formed by a chemical vapor deposition process in a temperature range of 1200°C to 1600°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 5 µm to 50 µm.
[0010] In some embodiments, the basal plane dislocation (BPD) density of the second crystal layer is less than 500 per cm 2 , the threading screw dislocation (TSD) density is less than 30 per cm 2 , and the basal stacking fault (BSF) density is 30 or less per wafer.
[0011] In some embodiments, the thickness T1 of the first crystal layer is 2000 µm or less, and the thickness T2 of the second crystal layer is 1000 µm or less.
[0012] A method for forming a silicon carbide crystal according to the present invention includes the following steps. Forming a silicon carbide seed crystal, wherein forming the silicon carbide seed crystal includes: forming a first crystal layer, wherein the first crystal layer includes a polycrystalline silicon carbide material; forming a second crystal layer, wherein the second crystal layer includes a single crystal silicon carbide material, and the thickness ratio (T2 / T1) of the thickness T1 of the first crystal layer to the thickness T2 of the second crystal layer is in the range of 10% to 50%; directly attaching the second crystal layer to the first crystal layer to form a silicon carbide seed crystal. Providing a raw material containing carbon and silicon elements in a reactor, and placing the silicon carbide seed crystal above the raw material. Performing a silicon carbide crystal growth process using the second crystal layer of the silicon carbide seed crystal as the growth plane, wherein the growth process includes heating the reactor and the raw material to form a silicon carbide crystal on the silicon carbide seed crystal.
[0013] In some embodiments, after forming the silicon carbide crystal, it further includes peeling off the second crystal layer from the silicon carbide seed crystal and reusing the first crystal layer to perform another silicon carbide crystal growth process.
[0014] In some embodiments, the polycrystalline silicon carbide material of the first crystal layer is formed by a physical vapor transport process in a temperature range of 1900°C to 2300°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the physical vapor transport process is 180 w / mK or more.
[0015] In some embodiments, the polycrystalline silicon carbide material of the first crystal layer is formed by a powder hot pressing process in a temperature range of 1800°C to 2100°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the powder hot pressing process is 100 w / mK or more.
[0016] In some embodiments, the polycrystalline silicon carbide material forming the first crystal layer is formed by chemical vapor deposition within a temperature range of 1200°C to 1600°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by chemical vapor deposition is above 150 w / mK.
[0017] The silicon carbide crystal of the present invention can be obtained by the above method for forming a silicon carbide crystal, wherein the basal plane dislocation (BPD) density of the silicon carbide crystal is less than 500 / cm 2 , the through screw dislocation (TSD) density is less than 20 / cm 2 or less, and the columnar stacking fault (BSF) density is 10 / wafers or less.
[0018] Based on the above, the embodiments of the present invention use a first crystal layer including a polycrystalline silicon carbide material and a second crystal layer including a single crystal silicon carbide material as silicon carbide seeds, and control the relative thickness of the first crystal layer and the second crystal layer. Accordingly, the silicon carbide crystal formed by the above silicon carbide seeds can have good geometric quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a schematic diagram of the structure of a silicon carbide seed according to some embodiments of the present invention;
[0020] Figure 2 is a schematic diagram of a crystal growth apparatus according to an embodiment of the present invention;
[0021] Figure 3 is a flowchart of a method for forming a silicon carbide crystal according to an embodiment of the present invention.
[0022] DESCRIPTION OF THE REFERENCE NUMERALS
[0023] 102: Reactor
[0024] 104: Induction coil
[0025] 106: Silicon carbide seed
[0026] 106A: Second crystal layer
[0027] 106B: First crystal layer
[0028] 108: Silicon carbide crystal
[0029] 110: Raw material
[0030] S10, S11, S12, S13, S20, S30: Steps
[0031] T1, T2: Thickness DETAILED DESCRIPTION
[0032] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.
[0033] Figure 1 is a schematic diagram of the structure of a silicon carbide seed crystal according to some embodiments of the present invention. Figure 2 is a schematic diagram of a crystal growth apparatus according to an embodiment of the present invention. Figure 3 is a flowchart of a method for forming a silicon carbide crystal according to an embodiment of the present invention. Hereinafter, reference will be made to Figure 1 the silicon carbide seed crystal and Figure 2 the crystal growth apparatus, in conjunction with Figure 3 the flowchart to describe a method for forming a silicon carbide crystal according to some embodiments of the present invention.
[0034] As shown in step S10 of Figure 1 and Figure 3 in the method for forming a silicon carbide crystal according to an embodiment of the present invention, a silicon carbide seed crystal 106 is pre-formed. In some embodiments, the method for forming the silicon carbide seed crystal 106 includes performing Figure 3 step S11 to form a first seed crystal layer 106B, where the first seed crystal layer 106B includes a polycrystalline silicon carbide material.
[0035] In some embodiments, the polycrystalline silicon carbide material of the first seed crystal layer 106B is formed by process A, by physical vapor transport (PVT) process in the temperature range of 1900°C to 2300°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the physical vapor transport process is 180 w / mK or more. In addition, the grain size of the formed polycrystalline silicon carbide material is in the range of 1 mm to 20 mm.
[0036] In another embodiment, the polycrystalline silicon carbide material of the first seed crystal layer 106B is formed by process B, by powder hot pressing process in the temperature range of 1800°C to 2100°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the powder hot pressing process is 100 w / mK or more. In addition, the grain size of the formed polycrystalline silicon carbide material is in the range of 1 µm to 500 µm.
[0037] In yet another embodiment, the polycrystalline silicon carbide material of the first seed crystal layer 106B is formed by process C, by chemical vapor deposition process in the temperature range of 1200°C to 1600°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the chemical vapor deposition process is 150 w / mK or more. In addition, the grain size of the formed polycrystalline silicon carbide material is in the range of 5 µm to 50 µm.
[0038] After forming the first crystal layer 106B, step S12 is then performed Figure 3 to form the second crystal layer 106A. The second crystal layer 106A includes a single-crystal silicon carbide material, and the basal plane dislocation (BPD) density of the second crystal layer 106A is less than 500 / cm 2 , the threading screw dislocation (TSD) density is less than 30 / cm 2 or less, and the basal stacking fault (BSF) density is 30 / wafers or less.
[0039] In some embodiments, the thickness ratio (T2 / T1) of the thickness T1 of the first crystal layer 106B to the thickness T2 of the second crystal layer 106A is controlled within the range of 10% to 50%. In some embodiments, the thickness ratio (T2 / T1) is controlled within the range of 30% to 50%. In other words, the first crystal layer 106B is a relatively thick seed crystal layer, and the second crystal layer 106A is a relatively thin seed crystal layer. In an exemplary embodiment, when the thickness ratio (T2 / T1) of the first crystal layer 106B to the second crystal layer 106A in the silicon carbide seed crystal 106 is controlled within the above range, the formed silicon carbide crystal can have better geometric quality.
[0040] In addition, in the case of meeting the above thickness ratio, the thickness T1 of the first crystal layer 106B is, for example, 2000 µm or less, and the thickness T2 of the second crystal layer 106A is, for example, 1000 µm or less. In some embodiments, the total thickness of the first crystal layer 106B and the second crystal layer 106A is, for example, 3000 µm or less.
[0041] After forming the second crystal layer 106A, step S13 is performed Figure 3 to directly bond the second crystal layer 106A onto the first crystal layer 106B to form the silicon carbide seed crystal 106. In the embodiment of the present invention, the second crystal layer 106A is bonded in a manner of directly contacting the surface of the first crystal layer 106B. In other words, there is no intermediate material between the first crystal layer 106B and the second crystal layer 106A. In some embodiments, the method of bonding the second crystal layer 106A includes ion implantation, reactive ion etching plasma (RIE plasma), epitaxy, chemical vapor deposition (CVD), surface activation, laser, combinations thereof, etc. to bond with the first crystal layer 106B.
[0042] Next, with reference to Figure 2 and Figure 3In step S20, a raw material 110 containing carbon and silicon elements and a silicon carbide seed crystal 106 (including a first seed crystal layer 106B and a second seed crystal layer 106A) above the raw material 110 are provided in a reactor 102. For example, the raw material 110 is, for example, silicon carbide powder, which is placed at the bottom end of the reactor 102 as a solid sublimation source. The silicon carbide seed crystal 106 is disposed at the top end of the reactor 102. In some embodiments, the silicon carbide seed crystal 106 can be fixed to a seed crystal carrier (not shown) through an adhesive layer, or fixed to the seed crystal carrier using other fixtures, and the present invention is not limited thereto. In some embodiments, the second seed crystal layer 106A of the silicon carbide seed crystal 106 is a crystal growth surface. Therefore, the silicon carbide seed crystal 106 is fixed to a seed crystal carrier (not shown) through the first seed crystal layer 106B.
[0043] Next, as shown in step S30 of Figure 2 and Figure 3 , a silicon carbide crystal growth process is performed to form a silicon carbide crystal 108 as shown in Figure 2 . For example, the silicon carbide crystal 108 is grown using the second seed crystal layer 106A of the silicon carbide seed crystal 106 as the crystal growth surface, and the growth process includes heating the reactor 102 and the raw material 100 to form the silicon carbide crystal 108 on the silicon carbide seed crystal 106.
[0044] In the above step S30, the silicon carbide crystal 108 is formed on the silicon carbide seed crystal 106 by Physical Vapor Transport (PVT). In some embodiments, the reactor 102 and the raw material 110 are heated by an induction coil 104 to form the silicon carbide crystal 108 on the silicon carbide seed crystal 106. In the process, the silicon carbide seed crystal 106 will receive the raw material 110 (silicon carbide powder) solidified from the gas state and slowly grow a semiconductor crystal on the silicon carbide seed crystal 106 until a silicon carbide crystal 108 with an expected size is obtained. After the silicon carbide crystal 108 grows to the expected size, the reactor 102 and the raw material 110 are cooled to obtain a silicon carbide ingot composed of the silicon carbide crystal 108. In some embodiments, the formed ingot may have different crystal structures depending on the crystal orientation of the single crystal seed used for the second seed crystal layer 106A. For example, the silicon carbide ingot includes 4H-silicon carbide, 6H-silicon carbide, etc. Both 4H-silicon carbide and 6H-silicon carbide belong to the hexagonal crystal system; in addition, the methods for forming the seed crystal 106 and the silicon carbide crystal 108 can both use Physical Vapor Transport (PVT), but different growth methods can also be adopted, and the present invention is not limited thereto.
[0045] In an embodiment of the present invention, when forming a silicon carbide crystal 108 through the above-mentioned silicon carbide seed crystal 106 having a first crystal layer 106B and a second crystal layer 106A, the formed silicon carbide crystal 108 can have better geometric quality. For example, the basal plane dislocation (BPD) density of the obtained silicon carbide crystal 108 can be controlled to be less than 500 / cm 2 , the through screw dislocation (TSD) density can be controlled to be less than 20 / cm 2 Hereinafter, and the basal stacking fault (BSF) density can be controlled to be 10 or less per wafer. After forming the silicon carbide crystal 108, the second crystal layer 106A can be peeled off from the silicon carbide seed crystal 106, and the first crystal layer 106B can be reused to perform another growth process of the silicon carbide crystal 108.
[0046] Example
[0047] In order to prove that the silicon carbide crystal 108 formed using the silicon carbide seed crystal 106 of the present invention has better quality, the following examples are specifically described.
[0048] In this embodiment, it is as described above Figures 1 to 3 shown steps, and various conditions for controlling the first crystal layer and the second crystal layer are as recorded in Tables 1 to 3 below to form a silicon carbide crystal. In the example of Table 1, the first crystal layer is formed by physical vapor transport method (Process A). In the example of Table 2, the first crystal layer is formed by powder hot pressing process (Process B). In the example of Table 3, the first crystal layer is formed by chemical vapor deposition process (Process C). The results of the formed silicon carbide crystals are shown in Tables 1 to 3 below.
[0049] Table 1
[0050]
[0051] Table 2
[0052]
[0053] Table 3
[0054]
[0055] Referring to the experimental results in Table 1, as shown in Examples A1 to A8, when the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is in the range of 10% to 50%, and the process conditions of the first crystal layer (i.e., the process conditions of physical vapor transport method) and the conditions of the second crystal layer are within a predetermined range, the obtained silicon carbide crystal can have better geometric quality (evaluation G). That is, the basal plane dislocation (BPD) density of the obtained silicon carbide crystal can be controlled to be less than 500 / cm 2 , the through screw dislocation (TSD) density can be controlled to be less than 20 / cm 2 , and the basal stacking fault (BSF) density can be controlled to be less than 10 per wafer.
[0056] In contrast, referring to Control Groups A1, A3, and A4, if the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is outside the range of 10% to 50%, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and basal stacking fault (BSF) density of the obtained silicon carbide crystal are all poor (evaluation NG). Referring to Control Group A2, even if the thickness ratio (T2 / T1) is in the range of 10% to 50%, if the grain size of the first crystal layer formed by physical vapor transport method is not in the range of 1 mm to 20 mm, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and basal stacking fault (BSF) density of the obtained silicon carbide crystal are also poor (evaluation NG). In addition, referring to Control Group A5, even if the thickness ratio (T2 / T1) is in the range of 10% to 50%, if the basal plane dislocation (BPD) density of the second crystal layer is not controlled to be less than 500 / cm 2 , the through screw dislocation (TSD) density is not controlled to be less than 30 / cm 2 , and the basal stacking fault (BSF) density is not controlled to be less than 30 per wafer, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and basal stacking fault (BSF) density of the obtained silicon carbide crystal are also poor (evaluation NG).
[0057] Referring to the experimental results in Table 2, as shown in Examples B1 to B8, when the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is in the range of 10% to 50%, and the process conditions of the first crystal layer (i.e., the process conditions of the powder hot pressing process) and the conditions of the second crystal layer are both within a predetermined range, the obtained silicon carbide crystal can have better geometric quality (Evaluation G). That is, the basal plane dislocation (BPD) density of the obtained silicon carbide crystal can be controlled to be less than 500 / cm 2 , the through screw dislocation (TSD) density can be controlled to be less than 20 / cm 2 , and the columnar stacking fault (BSF) density can be controlled to be 10 or less per wafer.
[0058] In contrast, referring to Control Groups B1, B3, and B4, if the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is outside the range of 10% to 50%, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and columnar stacking fault (BSF) density of the obtained silicon carbide crystal are all poor (Evaluation NG). Referring to Control Group B2, even if the thickness ratio (T2 / T1) is in the range of 10% to 50%, if the grain size of the first crystal layer formed by the powder hot pressing process is not in the range of 1 µm to 500 µm, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and columnar stacking fault (BSF) density of the obtained silicon carbide crystal are also poor (Evaluation NG). In addition, referring to Control Group B5, even if the thickness ratio (T2 / T1) is in the range of 10% to 50%, if the basal plane dislocation (BPD) density of the second crystal layer is not controlled to be less than 500 / cm 2 , the through screw dislocation (TSD) density is not controlled to be less than 30 / cm 2 , and the columnar stacking fault (BSF) density is not controlled to be 30 or less per wafer, then the basal plane dislocation (BPD) density, through screw dislocation (TSD) density, and columnar stacking fault (BSF) density of the obtained silicon carbide crystal are also poor (Evaluation NG).
[0059] Referring to the experimental results in Table 3, as shown in Examples C1 to C8, when the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is in the range of 10% to 50%, and the process conditions of the first crystal layer (i.e., the process conditions of the chemical vapor deposition process) and the conditions of the second crystal layer are both within a predetermined range, the obtained silicon carbide crystal can have better geometric quality (Evaluation G). That is, the basal plane dislocation (BPD) density of the obtained silicon carbide crystal can be controlled to be less than 500 / cm2 The threading screw dislocation (TSD) density can be controlled to be less than 20 / cm 2 or less, and the basal stacking fault (BSF) density can be controlled to be 10 or less per wafer.
[0060] In contrast, referring to control groups C1 - C2 and control groups C4 - C6, when the thickness ratio (T2 / T1) of the thickness of the first crystal layer to the thickness of the second crystal layer is outside the range of 10% to 50%, the basal plane dislocation (BPD) density, threading screw dislocation (TSD) density, and basal stacking fault (BSF) density of the obtained silicon carbide crystal are all poor (evaluation NG). Referring to control group C3, even if the thickness ratio (T2 / T1) is within the range of 10% to 50%, if the grain size of the first crystal layer formed in the chemical vapor deposition process is not within the range of 5 µm to 50 µm, and the basal plane dislocation (BPD) density of the second crystal layer is not controlled to be less than 500 / cm 2 the threading screw dislocation (TSD) density is not controlled to be less than 30 / cm 2 or less, and the basal stacking fault (BSF) density is not controlled to be 30 or less per wafer, then the basal plane dislocation (BPD) density, threading screw dislocation (TSD) density, and basal stacking fault (BSF) density of the obtained silicon carbide crystal are also poor (evaluation NG).
[0061] In summary, in the embodiments of the present invention, the first crystal layer including polycrystalline silicon carbide material and the second crystal layer including single - crystal silicon carbide material are used as silicon carbide seeds, and the relative thickness of the first crystal layer and the second crystal layer is controlled. Accordingly, the silicon carbide crystal formed by the above silicon carbide seeds can have good geometric quality. In addition, since the first crystal layer in the silicon carbide seeds can be reused, the cost of the seeds can be reduced while improving the quality of crystal growth, thereby greatly improving the competitiveness of the product.
Claims
1. A silicon carbide seed crystal, comprising: A first crystal layer, the first crystal layer comprising a polycrystalline silicon carbide material; A second crystal layer, directly attached to the first crystal layer, wherein the second crystal layer comprises a single crystal silicon carbide material, and the thickness ratio (T2 / T1) of the thickness T1 of the first crystal layer to the thickness T2 of the second crystal layer is in the range of 10% to 50%.
2. The silicon carbide seed crystal according to claim 1, wherein the thickness ratio (T2 / T1) is in the range of 30% to 50%.
3. The silicon carbide seed crystal according to claim 1, wherein, The polycrystalline silicon carbide material of the first crystal layer is formed by physical vapor transport process in the temperature range of 1900°C to 2300°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 1 mm to 20 mm.
4. The silicon carbide seed crystal according to claim 1, wherein, The polycrystalline silicon carbide material of the first crystal layer is formed by powder hot pressing process in the temperature range of 1800°C to 2100°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 1 µm to 500 µm.
5. The silicon carbide seed crystal according to claim 1, wherein, The polycrystalline silicon carbide material of the first crystal layer is formed by chemical vapor deposition process in the temperature range of 1200°C to 1600°C, and the grain size of the formed polycrystalline silicon carbide material is in the range of 5 µm to 50 µm.
6. The silicon carbide seed crystal according to claim 1, wherein, The basal plane dislocation (BPD) density of the second type of crystal layer is less than 500 / cm 2 , the threading screw dislocation (TSD) density is less than 30 / cm 2 , and the columnar stacking fault (BSF) density is 30 or less per wafer.
7. The silicon carbide seed crystal according to claim 1, wherein the thickness T1 of the first crystal layer is 2000 µm or less, and the thickness T2 of the second crystal layer is 1000 µm or less.
8. A method for forming a silicon carbide crystal, comprising: Forming a silicon carbide seed crystal, wherein forming the silicon carbide seed crystal comprises: Forming a first crystal layer, the first crystal layer comprising a polycrystalline silicon carbide material; Forming a second crystal layer, wherein the second crystal layer comprises a single crystal silicon carbide material, and the thickness ratio (T2 / T1) of the thickness T1 of the first crystal layer to the thickness T2 of the second crystal layer is in the range of 10% to 50%; Directly attaching the second crystal layer to the first crystal layer to form the silicon carbide seed crystal; Providing a raw material containing carbon element and silicon element into a reactor, and placing the silicon carbide seed crystal above the raw material; Growing a silicon carbide crystal using the second crystal layer of the silicon carbide seed crystal as the growth plane, wherein the growth process comprises heating the reactor and the raw material to form a silicon carbide crystal on the silicon carbide seed crystal.
9. The method according to claim 8, wherein after forming the silicon carbide crystal, further comprising peeling the second crystal layer from the silicon carbide seed crystal and reusing the first crystal layer to perform another silicon carbide crystal growth process.
10. The method according to claim 8, wherein, The polycrystalline silicon carbide material of the first crystal layer is formed by physical vapor transport process in the temperature range of 1900°C to 2300°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the physical vapor transport process is 180 w / mK or more.
11. The method according to claim 8, wherein, The polycrystalline silicon carbide material forming the first crystal layer is formed by a powder hot pressing process in a temperature range of 1800°C to 2100°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the powder hot pressing process is above 100 w / mK.
12. The method according to claim 8, wherein, The polycrystalline silicon carbide material forming the first crystal layer is formed by a chemical vapor deposition process in a temperature range of 1200°C to 1600°C, and the thermal conductivity of the polycrystalline silicon carbide material formed by the chemical vapor deposition process is above 150 w / mK.
13. A silicon carbide crystal, which is prepared by the method according to claim 8, wherein the basal plane dislocation (BPD) density of the silicon carbide crystal is less than 500 / cm 2 , the through-thickness screw dislocation (TSD) density is less than 20 / cm 2 hereinafter, and the columnar stacking fault (BSF) density is 10 or less per wafer.