Recycling method of incomplete silicon carbide wafer

Abstract

The invention provides a method for recycling incomplete silicon carbide wafers. The method comprises the following steps: providing two incomplete silicon carbide wafers with the same crystal form and consistent diameter; the incomplete wafer is cut, the sum of the distances from the circle center of the two cut wafers to the midpoint of the cutting edge is equal to the diameter of the target wafer, and the crystal orientation difference of the cutting section meets the set optimization condition; grinding and polishing the surface and the cutting surface of the cut wafer so as to control the surface roughness and perpendicularity deviation; then splicing the two wafers at high precision along the cutting surfaces to form a complete spliced seed crystal; and finally, carrying out single crystal growth in silicon carbide single crystal growth equipment by utilizing the spliced seed crystal. The method realizes high-quality reutilization of the splinters, remarkably reduces the waste rate of the silicon carbide wafers, improves the material utilization rate and the crystal quality, is suitable for the silicon carbide wafers with different crystal forms and dimensions, has the advantages of reducing the manufacturing cost and improving the recovery efficiency, and is suitable for wide popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide wafer processing, and more specifically, to a method for recycling defective silicon carbide wafers. Background Art

[0002] Silicon carbide (SiC), as a third-generation wide-bandgap semiconductor material, has excellent properties such as a wide bandgap, high thermal conductivity, excellent electron mobility, and high breakdown electric field strength. It can widely meet the stable operation requirements of power devices in high-temperature, high-voltage, and high-power environments, and is also suitable for the performance requirements of radio frequency devices in complex application scenarios such as high frequencies and strong radiation. For this reason, silicon carbide crystal materials have received extensive attention in high-end industries such as new energy vehicles, power electronics, and satellite communications.

[0003] Currently, the mainstream method for preparing silicon carbide single crystals is the physical vapor transport method (PVT method). In this method, a silicon carbide seed crystal and a silicon carbide source powder are usually placed in a graphite crucible, and the temperature of the crucible is raised above 2100 °C by induction heating, so that silicon carbide sublimes, is transported through the gas phase to the surface of the cooler seed crystal, and the epitaxial growth of the single crystal is gradually realized. However, under the combined action of high-temperature gradients and multi-source thermal stresses, internal residual stresses are easily accumulated in the crystal during the growth process. This stress mainly comes from the difference in thermal expansion coefficients between silicon carbide and graphite materials (4 - 5×10 -6 / K for SiC, 3.5 - 5.5×10 -6 / K for graphite), the spatial limitation of the crucible sidewall on the lateral growth of the crystal, and the thermal shrinkage stress generated during the subsequent cooling process, etc.

[0004] Due to the long-term accumulation of the above stresses in the crystal, during subsequent mechanical processing such as cutting, grinding, and polishing, the wafers are extremely prone to cracking, seriously affecting the wafer yield and causing high material losses. Especially for large-sized silicon carbide wafers, once local cracks appear, the entire wafer often fails to meet the device manufacturing requirements and is scrapped, increasing production costs and limiting the application scale of silicon carbide materials.

[0005] To alleviate the losses caused by wafer cracking, a method for closing cracks by adjusting growth process parameters has been proposed in Chinese Patent Application CN202111553871.2. However, in practical applications, this solution still has obvious limitations. Small-angle grain boundaries and microtube-like defects are easily formed in the crack region, resulting in large fluctuations in crystal quality and making it difficult to meet the strict requirements of high-performance electronic devices for the structural integrity and defect density of the substrate crystal.

[0006] Therefore, the existing technologies still face many challenges in the yield control of silicon carbide wafers and the reuse of cleaved wafers. There is an urgent need for a method for recycling defective silicon carbide wafers with high process feasibility, strong adaptability, and the ability to effectively improve the wafer utilization rate, so as to reduce the manufacturing cost and improve the raw material usage efficiency. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for recycling defective silicon carbide wafers to solve the problems of complex recycling process, high defect density, and low recycling efficiency existing in the prior art.

[0008] To overcome the defects of the above prior art, the present invention provides a method for recycling defective silicon carbide wafers, including the following steps: S1: Provide two defective silicon carbide wafers with the same crystal type and the same diameter, named the first defective wafer and the second defective wafer; S2: Cut the first defective wafer to obtain the first cut wafer, measure its bow height as D1, and then cut the second defective wafer to obtain the second cut wafer, measure its bow height as D2, and satisfy D1 + D2 = D, where D is the diameter of the complete wafer; the crystal orientation difference between the cut surface of the first cut wafer and the wafer positioning edge is α1, the crystal orientation difference between the cut surface of the second cut wafer and the wafer positioning edge is α2, the crystal orientations of the positioning edges of the two cut wafers are the same, and satisfy 15° ≤ |α1 - α2| ≤ 90°; S3: Grind and polish the cut surfaces of the first cut wafer and the second cut wafer processed in step S2; S4: Butt-join the first cut wafer and the second cut wafer processed in step S3 along the cut surface to form a spliced seed crystal; S5: Place the spliced seed crystal obtained in step S4 in a silicon carbide single crystal growth device for single crystal growth treatment, so as to realize the recycling of defective silicon carbide wafers and obtain a silicon carbide single crystal ingot with a certain thickness.

[0009] Compared with the prior art, the recycling method of defective silicon carbide wafers provided by this application has the following advantages: By reasonably selecting the cutting position and controlling the crystal orientation difference of the cutting surface, the present invention effectively optimizes the splicing interface, maximally utilizes the defective silicon carbide wafers, significantly improves the material recovery rate, and overcomes the problem in the prior art that a large number of residual pieces cannot be effectively recycled due to improper splicing. Through the optimization of the cutting, grinding and polishing, and splicing processes, the surface flatness and interface quality of the spliced wafers are ensured, the stress concentration and micro-defects at the interface are reduced, providing high-quality initial conditions for subsequent single crystal growth. In the cutting process of the present invention, the crystal orientation difference between the positioning edges of the two cut wafers is controlled within the range of 15° to 90°, and large-angle grain boundaries are induced to form in the splicing seam area during the crystal seeding stage. Large-angle grain boundaries can effectively block the dislocation propagation during the growth process of silicon carbide single crystals, thereby significantly reducing the defect density in the splicing area and overcoming the problem of high defect density caused by traditional random cutting and low-precision splicing.

[0010] Through precise cutting positioning, surface ultra-fine grinding and polishing, and high-precision splicing processes, the present invention effectively reduces the micro-defects on the wafer surface and the stress concentration at the interface. Combined with reasonable control of the single crystal growth conditions, the crystal quality of the spliced seed crystal growth area is ensured to be uniform and the defect density is low, realizing the improvement of the overall quality of silicon carbide single crystal materials.

[0011] In a possible implementation manner, in the step S1, the crystal orientation difference between the surfaces of the first defective wafer and the second defective wafer is less than 5.

[0012] Compared with the prior art, by controlling the crystal orientation difference between the surfaces of the spliced wafers to be less than 5°, the present invention effectively avoids the problem of mismatching of the splicing interface caused by too large crystal orientation differences. If the crystal orientation difference is large, small-angle grain boundaries are likely to form at the interface after splicing, thereby inducing the generation of cracks and defects. Small-angle grain boundaries will become the source of dislocation defects during the subsequent single crystal growth process and promote the further expansion of defects, seriously affecting the overall quality of silicon carbide single crystals. By controlling the crystal orientation difference within 5°, the consistency of the splicing interface can be significantly improved, and the formation of grain boundary defects can be suppressed from the source, ensuring the quality and stability of subsequent single crystal growth.

[0013] In a possible implementation manner, in the step S1, the first defective wafer and the second defective wafer have the same crystal type, and the crystal type is one of 4H type, 6H type, and 3C type.

[0014] By selecting defective wafers with consistent crystal types for splicing, the matching of lattice parameters is further ensured, and the mismatch stress and defects caused by the mismatch of crystal structures are avoided.

[0015] In a possible implementation manner, in the step S2, the diameter of the complete wafer is 4 inches, 6 inches, or 8 inches.

[0016] Compared with the prior art, adopting the above technical solution, the present invention standardizes subsequent process flows such as cutting, splicing, and polishing by setting standardized size specifications, which is beneficial to improving production efficiency, reducing the processing difficulty caused by inconsistent sizes, and enhancing process consistency, thereby simplifying the recycling process of silicon carbide wafers. In a possible implementation manner, in the step S3, the conditions for grinding and polishing treatment are: grinding and polishing until the surface roughness of the cutting surface is less than 1.5 nm, and the perpendicularity deviation between the cutting surface and the wafer surface is less than 0.5°.

[0017] Compared with the prior art, adopting the above technical solution, compared with the prior art, the present invention can significantly reduce the interface micro-irregularities and stress concentration phenomena by controlling the surface roughness below 1.5 nm and strictly controlling the perpendicularity deviation of the cutting surface to be less than 0.5°, further improving the bonding quality of the splicing interface, reducing the defect occurrence rate in the splicing area, and thus improving the crystal integrity in the subsequent single crystal growth process.

[0018] As a preferred solution, in the step S5, physical vapor transport method (PVT method) or liquid phase method is used for single crystal growth. Compared with the prior art, adopting the above technical solution, the physical vapor transport method has the advantages of controllable growth rate and high crystallization quality by sublimating the silicon carbide source material at high temperature and realizing vapor deposition growth on the seed crystal surface. The liquid phase method crystallizes the crystal from the melt by melting the silicon carbide source, which can reduce the growth temperature and thermal stress, and is beneficial to preparing high-quality large-size single crystals. Both methods can effectively control the crystal structure and defect density, and significantly improve the performance of the final product.

[0019] In a possible implementation manner, in the step S5, the conditions for the physical vapor transport method are: the growth temperature is 1800 - 2200 °C, and the growth time is 60 - 80 hours.

[0020] Compared with the prior art, adopting the above technical solution, the present invention optimizes the growth temperature and time interval of the physical vapor transport method, enabling the silicon carbide single crystal to grow slowly and stably under the optimal thermodynamic conditions, which helps to reduce the accumulation of thermal stress and improve the internal uniformity and defect control level of the crystal.

[0021] In a possible implementation manner, in the step S5, the conditions for the liquid phase method are: the growth temperature is 1500 - 1800 °C, and the growth time is 50 - 70 hours.

[0022] Compared with the prior art, adopting the above technical solution, by controlling the liquid phase growth temperature and time, the present invention effectively promotes the self-healing of internal defects of the crystal while reducing the risk of thermal cracks, and further improves the mechanical properties and electrical uniformity of the obtained silicon carbide single crystal.

[0023] In a possible implementation, in step S5, the full width at half maximum (FWHM) of the XRD rocking curve of the silicon carbide single crystal is less than 60 arcsec, and the defect density is lower than 4000 / cm 2 .

[0024] Compared with the prior art, the silicon carbide single crystal prepared by the method of the present invention can significantly improve the overall quality of the spliced single crystal, especially showing excellent performance in the control of crystal defects in the seed crystal splicing area. In the prior art, silicon carbide single crystals grown based on spliced seeds generally have problems of large fluctuations in crystal quality and high defect density in the splicing area, making it difficult to meet the quality requirements for high-end device applications.

[0025] By optimizing the wafer crystal orientation matching, surface treatment, splicing process and single crystal growth conditions, the finally prepared silicon carbide single crystal has a thickness of 10–50 mm, the full width at half maximum (FWHM) of the X-ray diffraction (XRD) rocking curve is controlled below 60 arcsec, and the defect density is lower than 4000 / cm². Through the above optimization measures, the method of the present invention effectively suppresses the lattice distortion and defect propagation at the splicing interface, ensuring that the silicon carbide single crystal has a low defect density and high crystal quality in the overall area, providing a reliable guarantee for the industrial application of large-size and high-performance silicon carbide single crystal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of wafer cutting in the present invention; Figure 2 is a schematic diagram of wafer splicing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] First of all, those skilled in the art should understand that these embodiments are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments according to needs to adapt to specific application scenarios.

[0028] The present invention provides a method for recycling defective silicon carbide wafers, including the following steps: S1: Provide two defective silicon carbide wafers with the same crystal form and the same diameter, named the first defective wafer and the second defective wafer; S2: As Figure 1As shown in the figure, a first cut wafer is obtained by cutting on a first defective wafer, and its bow height is measured as D1. Subsequently, a second cut wafer is obtained by cutting on a second defective wafer, and its bow height is measured as D2, and D1 + D2 = D is satisfied, where D is the diameter of the complete wafer; the crystal orientation difference between the cutting surface of the first cut wafer and the crystal orientation of the wafer positioning edge is α1, the crystal orientation difference between the cutting surface of the second cut wafer and the crystal orientation of the wafer positioning edge is α2, the crystal orientations of the wafer positioning edges are the same, and 15° ≤ |α1 - α2| ≤ 90° is satisfied; S3: Grind and polish the cutting surfaces of the first cut wafer and the second cut wafer processed in the step S2; S4: As Figure 2 shown in the figure, butt-join and splice the first cut wafer and the second cut wafer processed in the step S3 along the cutting surface to form a spliced seed crystal; S5: Place the spliced seed crystal obtained in the step S4 in a silicon carbide single crystal growth device for growth processing to complete the recycling of the defective silicon carbide wafer and obtain a silicon carbide single crystal. After the single crystal growth is completed, further analyze the crystal quality and defect distribution by XRD detection and alkali etching method.

[0029] As a preferred solution, in the step S1, the surface crystal orientation difference between the first defective wafer and the second defective wafer is less than 5.

[0030] As a preferred solution, in the step S1, the crystal forms of the first defective wafer and the second defective wafer are the same, and the crystal form is one of 4H type, 6H type, and 3C type.

[0031] As a preferred solution, in the step S2, the diameter of the complete wafer is 4 inches, 6 inches, or 8 inches.

[0032] As a preferred solution, in the step S3, the conditions for the grinding and polishing treatment are: grind and polish until the surface roughness of the cutting surface is less than 1.5 nm, and the perpendicularity deviation between the cutting surface and the surface of the cut wafer is less than 0.5°.

[0033] As a preferred solution, in the step S5, the growth treatment is to grow a single crystal by physical vapor transport method or liquid phase method.

[0034] As a preferred solution, in the step S5, the conditions for the physical vapor transport method are: the growth temperature is 1800 - 2200 °C, and the growth time is 60 - 80 hours.

[0035] As a preferred solution, in the step S5, the conditions for the liquid phase method are: the growth temperature is 1500 - 1800 °C, and the growth time is 50 - 70 hours.

[0036] As a preferred solution, in the step S5, the full width at half maximum of the XRD rocking curve of the silicon carbide single crystal is less than 60 arcsec, and the defect density is lower than 4000 / cm 2 .

[0037] The following combines the above technical solutions and provides embodiments with specific data to further expand and illustrate the above inventive content of the present invention: Embodiment 1: This embodiment provides a method for recycling defective silicon carbide wafers, which specifically includes the following steps: Step S1: Prepare two defective silicon carbide wafers with a crystal form of 4H and a diameter of 6 inches. The surface crystal orientation difference of each wafer is 3°, and each wafer retains a complete arc segment with an arc length exceeding one-fourth of the circumference. The sum of the remaining areas of the two wafers is greater than the area of a complete wafer.

[0038] Step S2: Cut on the defective wafer 1 to obtain the cut wafer 1, and measure the distance from its center to the midpoint of the cut edge as D1 = 60 mm. Then cut on the defective wafer 2 and measure the distance from its center to the midpoint of the cut edge as D2 = 90 mm, ensuring that D1 + D2 is equal to the diameter of the complete wafer, 150 mm. The orientation difference between the axial crystal orientation of the cut section and the orientation of the wafer positioning edge is α1 = 20°, and the orientation difference between the axial crystal orientation of the cut section and the orientation of the second wafer positioning edge is α2 = 60°, and the two satisfy 15° ≤ |α1 - α2| ≤ 90°.

[0039] Step S3: Perform fine grinding and polishing on the cut wafers to reduce the surface roughness to 1.8 nm, and control the vertical deviation between the wafer surface and the cut section within 0.8°.

[0040] Step S4: Accurately splice the two processed wafers to ensure that the surface crystal orientations on both sides of the splice seam are consistent, obtaining a complete spliced seed crystal.

[0041] Step S5: Place the spliced seed crystal in a physical vapor transport single crystal growth furnace and grow it for 72 hours under the condition of 1800°C - 2200°C to obtain a silicon carbide single crystal with a thickness of 25 mm. Crystal quality detection shows that the full width at half maximum of the XRD rocking curve of the silicon carbide crystal is about 50 arcsec, and the total defect density is about 3200 / cm 2 , meeting the high standard requirements for semiconductor device preparation.

[0042] Embodiment 2: This embodiment provides a method for recycling defective silicon carbide wafers, which specifically includes the following steps: Step S1: Select two incomplete silicon carbide wafers with a 6H crystal form and a diameter of 4 inches. The surface crystal orientation difference is 2°. Each wafer contains a complete arc segment with an arc length exceeding one-fourth of the circumference, and the total remaining area is greater than the area of a complete wafer.

[0043] Step S2: Cut on the incomplete wafer 1, with the length from the center of the circle to the midpoint of the cutting edge being D1 = 40 mm. Then cut on the incomplete wafer 2, with the length from the center of the circle to the midpoint of the cutting edge being D2 = 60 mm. The sum of the two is 100 mm, which is the diameter of a complete wafer. The orientation differences between the axial crystal orientation of the cutting section and the positioning edge of the wafer are α1 = 15° and α2 = 40° respectively, meeting the optimization requirements.

[0044] Step S3: Fine polish the surface and cross-section of the cut wafers to reduce the roughness to below 1.5 nm, and the perpendicularity deviation between the wafer surface and the cross-section is less than 0.6°.

[0045] Step S4: Perform precise splicing to obtain a complete spliced seed crystal.

[0046] Step S5: Place the spliced seed crystal in a single crystal growth furnace and grow the crystal using the liquid phase method. The temperature is set at 1500°C - 1800°C, and the growth time is 60 hours. Finally, a high-quality silicon carbide single crystal with a thickness of 20 mm is obtained. The XRD rocking curve full width at half maximum of the silicon carbide crystal is approximately 45 arcsec, and the defect density is approximately 2800 per cm 2 , and the crystal has excellent performance and is suitable for high-end semiconductor applications.

[0047] Example 3: This example provides a method for recycling incomplete silicon carbide wafers, which specifically includes the following steps: Step S1: Select two incomplete silicon carbide wafers with a 4H crystal form and a diameter of 8 inches. The surface crystal orientation difference is 1.5°. Each wafer retains a complete arc segment with an arc length exceeding one-fourth of the circumference, and the total remaining area of the two wafers is significantly greater than the area of a complete wafer.

[0048] Step S2: Cut on the incomplete wafer 1 to obtain a length D1 = 95 mm from the center of the circle to the midpoint of the cutting edge; cut on the incomplete wafer 2 to obtain a length D2 = 105 mm from the center of the circle to the midpoint of the cutting edge. The sum is 200 mm, which is the diameter of a standard 8-inch wafer. The orientation differences between the axial crystal orientation of the cutting section and the [11 - 20] positioning edge of the wafer are α1 = 25° and α2 = 55° respectively, and the difference between the two is 30°, meeting the optimization conditions for large-angle grain boundary splicing.

[0049] Step S3: Fine grind and polish the two wafers to reduce the surface roughness to 1.2 nm, and the perpendicularity deviation between the surface and the cross-section is less than 0.5°.

[0050] Step S4: Precision splice two wafers into a complete spliced seed crystal.

[0051] Step S5: Place the spliced seed crystal and silicon carbide raw materials into a physical vapor transport single crystal growth furnace, and carry out single crystal growth for 80 hours at a temperature of 1800°C - 2100°C to obtain a complete silicon carbide single crystal with a thickness of 25 mm. After crystal quality inspection and analysis, the full width at half maximum of the XRD rocking curve of the silicon carbide crystal is about 52 arcsec, and the crystal defect density is about 3500 per cm 2 , meeting the application requirements of high-performance semiconductor substrates.

[0052] Through the verification of Examples 1 to 3, the method for recycling defective silicon carbide wafers proposed by the present invention demonstrates excellent technical performance and remarkable application effects, effectively solving the technical bottlenecks existing in the current silicon carbide wafer recycling process. By precisely controlling the cutting position and the crystallographic orientation difference of the cutting surface, the formation of small-angle grain boundaries and microtube defects at the splicing interface is avoided, significantly improving the structural integrity and crystal quality of the spliced silicon carbide single crystal. The full width at half maximum of the XRD rocking curve of the obtained single crystal is less than 60 arcsec, and the defect density is lower than 4000 per cm², meeting the strict requirements for the manufacture of high-performance semiconductor devices. Through the collaborative optimization of the cutting and grinding and polishing steps, the present invention achieves an extremely low surface roughness of the cutting surface, precisely controls the crystal orientation, significantly reduces the stress concentration at the splicing interface, inhibits the expansion of internal defects during crystal growth, and improves the mechanical and thermal stability of the crystal. Through the method of the present invention, defective silicon carbide wafers can be efficiently spliced and used for single crystal growth, greatly improving the material utilization rate, reducing waste generation, lowering production costs, and enhancing the economic efficiency of the recycling process. Through the integrated optimization of precise cutting, grinding and polishing, splicing and single crystal growth, the complex crystal repair steps in the traditional process are avoided, the overall recycling process flow is simplified, and the efficiency and yield of single crystal growth are improved. The method of the present invention is applicable to both the physical vapor transport method (PVT method) and the liquid phase single crystal growth process, with strong adaptability. The prepared silicon carbide single crystal has excellent quality, providing an efficient and sustainable defective wafer recycling and reuse solution for the semiconductor industry, and having broad application prospects.

[0053] In summary, through precise cutting, surface ultra-fine polishing, high-precision splicing and optimized single crystal growth process, the present invention forms a process synergy effect, successfully solving the problems of complex crystal recycling process, high defect density and low recycling efficiency in the prior art. The obtained silicon carbide single crystal has stable and reliable quality, meets the stringent requirements of high-end semiconductor devices for crystal substrates, and has extremely high industrial application value and promotion potential.

[0054] In the description of the present application, the descriptions referring to terms such as "one embodiment", "some embodiments", "in this embodiment", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0055] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for recycling defective silicon carbide wafers, characterized in that, Including the following steps: S1: Provide two incomplete silicon carbide wafers with the same crystal form and the same diameter, named the first incomplete wafer and the second incomplete wafer; S2: Cut the first incomplete wafer to obtain the first cut wafer, measure its bow height as D1, and then cut the second incomplete wafer to obtain the second cut wafer, measure its bow height as D2, and satisfy D1 + D2 = D, where D is the diameter of the complete wafer; the crystal orientation difference between the cutting surface of the first cut wafer and the wafer positioning edge is α1, the crystal orientation difference between the cutting surface of the second cut wafer and the wafer positioning edge is α2, the crystal orientations of the positioning edges of the two cut wafers are the same, and satisfy 15° ≤ |α1 - α2| ≤ 90°; S3: Grind and polish the cutting surfaces of the first cut wafer and the second cut wafer processed in step S2; S4: Butt-join and splice the first cut wafer and the second cut wafer processed in step S3 along the cutting surface to form a spliced seed crystal; S5: Place the spliced seed crystal obtained in step S4 in a silicon carbide single crystal growth device for growth treatment, complete the recycling of the incomplete silicon carbide wafer, and obtain a silicon carbide single crystal ingot.

2. The recycling method of the defective silicon carbide wafer according to claim 1, wherein In step S1, the surface crystal orientation difference between the first incomplete wafer and the second incomplete wafer is less than 5°.

3. The recycling method of the defective silicon carbide wafer according to claim 1, characterized in that In step S1, the first incomplete wafer and the second incomplete wafer have the same crystal form, and the crystal form is one of 4H type, 6H type, and 3C type.

4. The recycling method of the defective silicon carbide wafer according to claim 3, characterized in that, In step S2, the diameter of the complete wafer is 4 inches, 6 inches, or 8 inches.

5. The recycling method of the defective silicon carbide wafer according to claim 1, characterized in that, In step S3, the conditions for the grinding and polishing treatment are: grind and polish until the surface roughness of the cutting surface is less than 1.5 nm, and the perpendicularity deviation between the cutting surface and the surface of the cut wafer is less than 0.5°.

6. The recycling method of the defective silicon carbide wafer according to claim 1, characterized in that, In step S5, the growth treatment is to grow single crystals by physical vapor transport method or liquid phase method.

7. The recycling method of the defective silicon carbide wafer according to claim 6, characterized in that, In step S5, the conditions for the physical vapor transport method are: the growth temperature is 1800 - 2200 °C, and the growth time is 60 - 80 hours.

8. The recycling method of the defective silicon carbide wafer according to claim 6, characterized in that, In step S5, the conditions for the liquid phase method are: the growth temperature is 1500 - 1800 °C, and the growth time is 50 - 70 hours.

9. The recycling method of the defective silicon carbide wafer according to claim 6, wherein In the step S5, the thickness of the silicon carbide single crystal ingot is 10 - 50 mm, the full width at half maximum of the XRD rocking curve is less than 60 arcsec, and the defect density is lower than 4000 / cm 2 .

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