Investigation of anodic oxidation mechanism of 4H-SiC (0001) for electrochemical mechanical polishing

In an attempt to realize the high-quality and highly efficient polishing of SiC, the anodic oxidation mechanism of SiC was studied to enable the application of electrochemical mechanical polishing (ECMP). Through linear scanning voltammetry (LSV) and anodic oxidation experiments, the etch pits on the processed surface were found to be generated by oxidation on the sites where breakdown occurs in the anodic oxidation process. The origin of the etch pits was investigated through observing the same area on a SiC substrate during the oxidation process using atomic force microscopy (AFM), and they were confirmed to be atomic-scale pits mechanically introduced in the chemical mechanical polishing (CMP) process. The Deal-Grove model was used to model the growth process of the etch pits. It was found that their growth is controlled by a charge transfer process in the initial growth stage, which changes to a diffusion process in the late growth stage. The results of this research provide a reference for obtaining atomically smooth SiC surfaces by applying ECMP.