Method for preparing silicon carbide wafer and silicon carbide wafer
A method for preparing a SiC ingot includes: disposing a raw material and a SiC seed crystal facing each other in a reactor having an internal space; subliming the raw material by controlling a temperature, a pressure, and an atmosphere of the internal space; growing the SiC ingot on the seed crystal; and collecting the SiC ingot after cooling the reactor. The wafer prepared from the ingot, which is prepared from the method, generates cracks when an impact is applied to a surface of the wafer, the impact is applied by an external impact source having mechanical energy, and a minimum value of the mechanical energy is 0.194 J to 0.475 J per unit area (cm 2 ).
1. A method for preparing a wafer, comprising:
disposing a raw material and a SiC seed crystal facing each other in a reactor having an internal space;
subliming the raw material by controlling a temperature, a pressure, and an atmosphere of the internal space;
growing the SiC ingot on the seed crystal;
collecting the SiC ingot after cooling the reactor;
grinding an edge of the SiC ingot; and
cutting the ground SiC ingot to prepare the wafer,
wherein a thermal conductivity of the reactor is 120 W/mK or less.
2. The method of claim 1 , wherein the growing the SiC ingot on the seed crystal or the cooling the reactor is performed in an inert gas atmosphere having a flow in a direction from the raw material to the seed crystal.
3. The method of claim 2 , wherein the growing the SiC ingot on the seed crystal is performed in the inert gas atmosphere having a flow rate of 70 sccm to 330 sccm.
4. The method of claim 2 , wherein cooling the reactor is performed in the inert gas atmosphere having a flow rate of 1 sccm to 300 sccm.
5. The method of claim 3 , wherein the temperature of the internal space is increased at a temperature increase rate of 1° C./min to 10° C./min.
6. The method of claim 4 , wherein the cooling the reactor is performed at a cooling rate of 1° C./min to 10° C./min.
7. A wafer prepared from the method of claim 1 ,
wherein when an impact is applied to a surface of the wafer, cracks are generated at the surface,
wherein the impact is applied by an external impact source having mechanical energy, and
wherein a minimum value of the mechanical energy is 0.194 J to 0.475 J per unit area (cm 2 ).
8. The wafer of claim 7 , wherein an area of the surface to which the impact is applied is 100 mm 2 or less.
9. The wafer of claim 7 , wherein the minimum value of the mechanical energy is 0.233 J to 0.475 J per unit area (cm 2 ).
10. The wafer of claim 7 , wherein the wafer comprises a 4H-SiC structure and has a diameter of 4 inches or more.
11. The wafer of claim 7 , wherein the impact is applied by dropping the external impact source on the surface of the wafer at a predetermined height from the surface of the wafer.
12. The wafer of claim 7 , wherein the wafer has a micropipe (MP) density of 1.5/cm 2 or less.
13. The wafer of claim 7 , wherein the wafer has a threading edge dislocation (TED) density of 10,000/cm 2 or less.
14. The wafer of claim 7 , wherein the wafer has basal plane dislocation (BPD) density of 5,000/cm 2 or less.
15. The wafer of claim 7 , wherein the thickness of the wafer is 300 μm to 600 μm.
16. The wafer of claim 7 , wherein the wafer is substantially a single crystal 4H-SiC structure.
17. A wafer prepared from the method of claim 1 ,
wherein the wafer has a crack-generated drop height of 100 mm or more, and
wherein the crack-generated drop height is measured by a Dupont impact tester with the wafer having a thickness of 360 μm and a hammer having a weight of 25 g.
18. The wafer of claim 17 , wherein the crack-generated drop height is measured by the Dupont impact tester with a concave die having a diameter of 4 mm.
19. The wafer of claim 17 , wherein the crack-generated drop height is 150 mm or more.
20. The wafer of claim 17 , wherein the wafer comprises a 4H-SiC structure and has a diameter of 4 inches or more.