Anodic oxidation behaviors of 4H-SiC for guiding electrochemical mechanical polishing

Due to its high hardness, chemical inertness and brittleness, 4H-SiC is difficult to achieve a nanoscale smooth surface through traditional cutting and grinding. Electrochemical mechanical polishing (ECMP) combined with anodic oxidation and mechanical grinding can achieve a nano-scale smooth 4H-SiC surface. Selecting the appropriate potentials of rough polishing and fine polishing is the key to achieving efficient ECMP. In this work, anodic oxidation behaviors of 4H-SiC are investigated at different potential (φ). For φ<breakdown potential, the uneven distribution of current density is conducive to the fine polishing process. For breakdown potential<φ<oxygen evolution potential, passivation - pitting corrosion process occurs on the surface of 4H-SiC, which is beneficial to the rough polishing process. Based on this, a two-step ECMP process is designed, and the sub-nanometer 4H-SiC surface (Sa = 0.892 nm) is obtained efficiently.