**5. Conclusions**

This study entailed experiments and RMD simulations to investigate the mechanisms of the reaction between SiC and water during nanoscale scratching in the absence of any chemical reagents. The material removal behavior of SiC at the nanoscale level was analyzed, and the mechanisms of the SiC–water reaction were summarized. The following conclusions were drawn:

(1) A regular plastic scratch with nanometer depth and almost no evident cracks was ob-

tained using diamond abrasives to scratch 4H-SiC C face (000 − 1) without any chemical agent, and the formation of amorphous SiO<sup>2</sup> was clearly observed, which verified that the SiC–water reaction occurred in the SiC plastic removal stage.


tioned from plastic to brittle and thereby achieved a controllable behavior in the plastic domain of SiC under controlled loading, which indirectly controlled the SiC– water reaction. Conversely, the controllable behavior of the SiC–water reaction at the nanoscale during RMD simulations was primarily achieved by adjusting the friction depth. Therefore, both experiments and simulations regulated the load, thereby regulating the friction depth to control the occurrence of the SiC–water reaction.

(4) The main factors controlling the SiC–water reaction were the load and contact states, and the secondary factors were the speed and temperature. The SiC–water reaction could occur smoothly at low temperatures as long as a suitable load and contact state were maintained. Therefore, microcracks could be reasonably avoided by the effective application of the SiC–water reaction in the subsequent SiC thinning process, thus improving the surface quality of SiC wafers.

**Author Contributions:** Experiment, data analysis, and writing, Z.C. and Q.L.; conception, material characterization and analysis, J.L. and Q.L.; software and data analysis, Z.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Natural Science Foundation of China, grant numbers 51975222 and 52005190, and Natural Science Foundation of Fujian Province, grant numbers 2021J06027 and 2021J05060.

**Conflicts of Interest:** The authors declare no conflict of interest.
