*Article* **Understanding the Mechanisms of SiC–Water Reaction during Nanoscale Scratching without Chemical Reagents**

**Zhihao Cheng <sup>1</sup> , Qiufa Luo 1,\* , Jing Lu 2,\* and Zige Tian <sup>1</sup>**


**Abstract:** Microcracks inevitably appear on the SiC wafer surface during conventional thinning. It is generally believed that the damage-free surfaces obtained during chemical reactions are an effective means of inhibiting and eliminating microcracks. In our previous study, we found that SiC reacted with water (SiC–water reaction) to obtain a smooth surface. In this study, we analyzed the

interfacial interaction mechanisms between a 4H-SiC wafer surface (000 − 1) and diamond indenter during nanoscale scratching using distilled water and without using an acid–base etching solution. To this end, experiments and ReaxFF reactive molecular dynamics simulations were performed. The results showed that amorphous SiO<sup>2</sup> was generated on the SiC surface under the repeated mechanical action of the diamond abrasive indenter during the nanoscale scratching process. The SiC–water reaction was mainly dependent on the load and contact state when the removal size of SiC was controlled at the nanoscale and the removal mode was controlled at the plastic stage, which was not significantly affected by temperature and speed. Therefore, the reaction between water and SiC on the wafer surface could be controlled by effectively regulating the load, speed, and contact area. Microcracks can be avoided, and damage-free thinning of SiC wafers can be achieved by controlling the SiC–water reaction on the SiC wafer surface.

**Keywords:** 4H-SiC wafer; amorphous silica; ReaxFF reactive molecular dynamics; plastic removal; chemical reaction
