Silicon carbide wafers with relaxed positive bow and related methods

Patent metadata

Field	Value
Publication number	US-11654596-B2
Application number	US-202117178532-A
Country	US
Kind code	B2
Filing date	Feb 18, 2021
Priority date	May 17, 2019
Publication date	May 23, 2023
Grant date	May 23, 2023

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 diameter of at least 200 millimeters (mm); and
a relaxed positive bow from the silicon face.

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

3. The SiC wafer of claim 1 , wherein the relaxed positive bow is in a range from greater than 0 μm to 40 μm.

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

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

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

7. The SiC wafer of claim 1 , wherein the SiC wafer comprises an n-type conductive SiC wafer.

8. The SiC wafer of claim 1 , wherein the SiC wafer comprises a semi-insulating SiC wafer.

9. The SiC wafer of claim 1 , wherein the SiC wafer comprises an unintentionally doped SiC wafer.

10. 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.

11. 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.

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

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

14. A silicon carbide (SiC) wafer comprising:
a silicon face and a carbon face; and
a relaxed positive bow from the silicon face, wherein the relaxed positive bow is provided with a kerf loss of less than 250 μm.

15. The SiC wafer of claim 14 , wherein the kerf loss is less than 175 μm.

16. The SiC wafer of claim 14 , wherein the kerf loss is in a range from 100 μm to 250 μm.

17. The SiC wafer of claim 14 , wherein the kerf loss is in a range from 80 μm to 140 μm.

18. A silicon carbide (SiC) wafer comprising a silicon face, a carbon face, a diameter of at least 200 mm, and a relaxed positive bow from the silicon face, wherein the SiC wafer is formed by a process of separating the SiC wafer from a SiC bulk crystalline material along a subsurface laser damage pattern.

19. The SiC wafer of claim 18 , wherein the relaxed positive bow is in a range from greater than 0 μm to 50 μm.

20. The SiC wafer of claim 18 , wherein the relaxed positive bow is in a range including 30 um to 50 um.

21. The SiC wafer of claim 18 , wherein the carbon face of the SiC wafer comprises a shape that corresponds to the relaxed positive bow from the silicon face.

22. The SiC wafer of claim 18 , 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.

23. The SiC wafer of claim 18 , wherein the SiC wafer is provided with a kerf loss of less than 250 μm.

24. The SiC wafer of claim 18 , 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