Study on material removal mechanism of 6H-SiC single crystal wafer based on different nano-scratch order

The (0001) surface of 6H-SiC single crystal were scratched with different intervals and different orders by micro-nano mechanical test system. The cross section profile curve of the scratch, the scratch depth, the friction force and the surface morphology on the wafer surface were analyzed by friction sensor, super depth-of-field microscope system and 3D topography instrument. The material removal process under different intervals and different orders in the process of single crystal wafer scratching were studied. The results show that when the static load is 100 mN, the cross section profile and the average friction force of the single crystal surface are affected by different scratch intervals. With the increase of scratch interval, the depth difference between two scratches decreases gradually, and the average friction of scratch 2 gradually decreases and approches that of scratch 1. When the scratch interval is 14 μm, the maximum scratch depth is -183.4 nm and the average friction force is 18.8 mN. The scratch order has a significant effect on the surface morphology and the material removal. When the static load is 90 mN, the scratch interval is 6 μm and 8 μm, the surface material accumulation of non-sequential scratche is less, the wafer surface roughness value is lower, and its surface quality is better. When the scratch interval is 6 μm, the material on the end surface of sequential-scratches is seriously broken under uniform dynamic load of 0~180 mN, while non-sequential scratches can reduce the crack degree of wafer scratches to a certain extent. The maximum friction force in sequential-scratches is 76.8 mN, which is greater than 63.3 mN in non-sequential scratches. Non-sequential scratches are more helpful to realize the plastic processing of SiC wafer and improve its surface processing quality.