Silicon carbide wafers with relaxed positive bow and related methods
View Patent ↗Silicon carbide (SiC) wafers and related methods are disclosed that include intentional or imposed wafer shapes that are configured to reduce manufacturing problems associated with deformation, bowing, or sagging of such wafers due to gravitational forces or from preexisting crystal stress. Intentional or imposed wafer shapes may comprise SiC wafers with a relaxed positive bow from silicon faces thereof. In this manner, effects associated with deformation, bowing, or sagging for SiC wafers, and in particular for large area SiC wafers, may be reduced. Related methods for providing SiC wafers with relaxed positive bow are disclosed that provide reduced kerf losses of bulk crystalline material. Such methods may include laser-assisted separation of SiC wafers from bulk crystalline material.
1. A crystalline material processing method comprising:
providing a bulk crystalline material comprising silicon carbide (SiC); and
separating a SiC wafer from the bulk crystalline material such that the SiC wafer forms a relaxed positive bow from a silicon face of the SiC wafer, and a kerf loss associated with forming the SiC wafer from the bulk crystalline material is less than 250 microns (μm).
2. The crystalline material processing method of claim 1 , wherein the kerf loss is less than 175 μm.
3. The crystalline material processing method of claim 1 , wherein the kerf loss is in a range including 100 μm to 250 μm.
4. The crystalline material processing method of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 μm to 50 μm.
5. The crystalline material processing method of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 μm to 40 μm.
6. The crystalline material processing method of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 μm to 15 μm.
7. The crystalline material processing method of claim 1 , wherein the relaxed positive bow is in a range including 30 μm to 50 μm.
8. The crystalline material processing method of claim 1 , wherein the relaxed positive bow is in a range including 8 μm to 16 μm.
9. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 250.
10. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 300.
11. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 400.
12. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises a diameter to thickness ratio in a range including 250 to 1020.
13. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises an n-type conductive SiC wafer.
14. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises a semi-insulating SiC wafer.
15. The crystalline material processing method of claim 1 , wherein the SiC wafer comprises an unintentionally doped SiC wafer.
16. The crystalline material processing method of claim 1 , wherein a carbon face of the SiC wafer comprises a shape that corresponds to the relaxed positive bow from the silicon face.
17. The crystalline material processing method of claim 1 , wherein a profile of the silicon face that is defined by the relaxed positive bow differs from a profile of a carbon face of the SiC wafer.
18. A crystalline material processing method comprising:
providing a bulk crystalline material comprising silicon carbide (SiC);
forming a subsurface laser damage pattern within the bulk crystalline material; and
separating a SiC wafer from the bulk crystalline material along the subsurface laser damage pattern such that the SiC wafer comprises a relaxed positive bow from a silicon face of the SiC wafer.
19. The crystalline material processing method of claim 18 , wherein the relaxed positive bow is in a range from greater than 0 μm to 50 μm.
20. The crystalline material processing method of claim 18 , wherein the relaxed positive bow is in a range from greater than 0 μm to 15 μm.
21. The crystalline material processing method of claim 18 , wherein the relaxed positive bow is in a range including 30 μm to 50 μm.
22. The crystalline material processing method of claim 18 , wherein the relaxed positive bow is in a range including 8 μm to 16 μm.
23. The crystalline material processing method of claim 18 , wherein said forming the subsurface laser damage pattern comprises variably adjusting a laser power across the bulk crystalline material to form a nonlinear profile of the subsurface laser damage pattern such that the relaxed positive bow is provided after separation.
24. The crystalline material processing method of claim 18 , wherein said forming the subsurface laser damage pattern comprises variably adjusting a focal point of a laser across the bulk crystalline material to form a nonlinear profile of the subsurface laser damage pattern such that the relaxed positive bow is provided after separation.
25. The crystalline material processing method of claim 18 , wherein the bulk crystalline material is arranged with a radial doping profile such that laser absorption during said forming the subsurface laser damage pattern forms a nonlinear profile of the subsurface laser damage pattern such that the relaxed positive bow is provided after separation.
26. The crystalline material processing method of claim 18 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 250.
27. The crystalline material processing method of claim 18 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 300.
28. The crystalline material processing method of claim 18 , wherein the SiC wafer comprises a diameter to thickness ratio of at least 400.
29. The crystalline material processing method of claim 18 , wherein the SiC wafer comprises a diameter to thickness ratio in a range including 250 to 1020.
30. The crystalline material processing method of claim 18 , wherein a kerf loss associated with forming the SiC wafer from the bulk crystalline material is less than 250 microns (μm).