Method of manufacturing silicon carbide seed crystal and method of manufacturing silicon carbide ingot

A method of manufacturing silicon carbide seed crystals, comprising:

• disposing a silicon carbide based raw material in a crucible;
• disposing a silicon carbide seed crystal on a top of the crucible;
• heating the silicon carbide based raw material to form a thermal field in the crucible so that the silicon carbide based raw material is sublimated in the thermal field of the crucible, wherein a radial temperature gradient of the thermal field in the crucible is greater than or equal to 5° C./cm and less than or equal to 50° C./cm;
• growing a silicon carbide single crystal from the sublimed silicon carbide after being in contact with the seed crystal disposed on the top of the crucible;
• and
• growing the silicon carbide single crystal on the seed crystal continuously to obtain a silicon carbide ingot silicon carbide ingot;
• wherein the silicon carbide seed crystal located on the top of the crucible is a first seed crystal, the silicon carbide ingot obtained by the growth of the first seed crystal and processed to satisfy D≤25% is a second seed crystal, wherein the second seed crystal comprises a silicon surface and a carbon surface opposite to the silicon surface, a difference D between a basal plane dislocation density BPD1 of the silicon surface and a basal plane dislocation density BPD2 of the carbon surface satisfies a formula (1) as follows:
• D=(BPD1−BPD2)/BPD1≤25% (1);
• and
• wherein the method further comprises:
• disposing the second seed crystal on a top of a crucible to grow a silicon carbide single crystal on the second seed crystal to grow an Nth silicon carbide ingot;
• and
• reusing the same second seed crystal to grow an N+1th silicon carbide ingot on the second seed crystal,
• wherein growing the N+1th silicon carbide ingot comprises:
• disposing the reused second seed crystal on a top of a crucible;
• disposing a silicon carbide based raw material in the crucible;
• heating the silicon carbide based raw material so that the silicon carbide based raw material is sublimed in a thermal field of the crucible, wherein a radial temperature gradient of the thermal field in the crucible is greater than or equal to 5° C./cm and less than or equal to 50° C./cm;
• growing a silicon carbide single crystal from the sublimed silicon carbide after being in contact with the silicon carbide seed crystal;
• and
• growing the silicon carbide single crystal continuously on the silicon carbide seed crystal to obtain an N+1th silicon carbide ingot.