*2.1. Materials*

The 6H n-type SiC Dummy Grade wafers (the C face and Si face can be identified by the primary orient flat and secondary orient flat) purchased from tankeBlue Semiconductor Co. Ltd., Beijing, China were used in this experiment. Indentation and nanoscratching tests were performed on the polished wafers and grinding and lapping experiments were carried out on the as-cut wafers and double side lapped wafers. The wafers are 300 ± 10 μm thick, the surface roughness Ra of these as-cut wafers, double side lapped wafers, and polished wafers are about 0.21 μm, 73 nm, and 0.3 nm, respectively.
