Silicon carbide wafers with relaxed positive bow and related methods

Patent metadata

Field	Value
Publication number	US-12070875-B2
Application number	US-202318297144-A
Country	US
Kind code	B2
Filing date	Apr 7, 2023
Priority date	May 17, 2019
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

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.

First claim

What is claimed is:

1. A silicon carbide (SiC) wafer comprising:
a silicon face and a carbon face;
a radial doping profile that is variable from a perimeter of the SiC wafer to a center of the SiC wafer; and
a relaxed positive bow from the silicon face.

2. The SiC wafer of claim 1 , wherein the radial doping profile comprises a lower doping region near the perimeter of the SiC wafer and a higher doping region that is closer to the center of the SiC wafer than the perimeter of the SiC wafer.

3. The SiC wafer of claim 1 , wherein the higher doping region is positioned at the center of the SiC wafer.

4. The SiC wafer of claim 1 , wherein the higher doping region is positioned offset from the center of the SiC wafer.

5. The SiC wafer of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 pm to 50 pm.

6. The SiC wafer of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 pm to 15 pm.

7. The SiC wafer of claim 1 , wherein the relaxed positive bow is in a range including 30 pm to 50 pm.

8. The SiC wafer of claim 1 , wherein the relaxed positive bow is in a range including 8 pm to 16 pm.

9. The SiC wafer of claim 1 , wherein the carbon face of the SiC wafer comprises a shape that corresponds to the relaxed positive bow from the silicon face.

10. The SiC wafer of claim 1 , wherein a profile of the silicon face that is defined by the relaxed positive bow differs from a profile of the carbon face of the SiC wafer.

11. The SiC wafer of claim 1 , wherein the SiC wafer is provided with a kerf loss of less than 250 pm.

12. The SiC wafer of claim 1 , wherein a diameter of the SiC wafer is in a range from 200 mm to 205 mm.

13. A silicon carbide (SiC) wafer comprising:
a silicon face and a carbon face;
a diameter of at least 200 millimeters (mm);
a radial doping profile that is variable from a perimeter of the SiC wafer to a center of the SiC wafer;
a relaxed positive bow from the silicon face; and
wherein a profile of the silicon face that is defined by the relaxed positive bow differs from a profile of the carbon face of the SiC wafer.

14. The silicon carbide wafer of claim 13 , wherein a surface of the SiC wafer is misaligned with a crystallographic c-plane by an oblique angle relative to the crystallographic c-plane.

15. The silicon carbide wafer of claim 14 , wherein the oblique angle is in a range from 1 to 10 degrees.

16. The silicon carbide wafer of claim 14 , wherein the oblique angle is in a range from 2 to 6 degrees.

17. The silicon carbide wafer of claim 14 , wherein the oblique angle is 4 degrees.

18. The SiC wafer of claim 13 , wherein the diameter is in a range from 200 mm to 205 mm.

Assignees

• Wolfspeed Inc

Inventors

• Bubel Simon
• Donofrio Matthew
• Edmond John
• Currier Ian

Classifications

• C30B29/36

  Carbides · CPC title

• H10D62/8325 Primary

  Silicon carbide · CPC title

• B28D5/0011 Primary

  with preliminary treatment, e.g. weakening by scoring · CPC title

• H01L29/1608

  Electricity · mapped topic

• H10P14/2904

  Silicon carbide · CPC title