Oxidation mechanism of 4H-SiC in slurry-less ECMP with weak alkaline electrolyte

Abstract

4H-SiC is crucial for high-temperature, high-power semiconductors, yet its processing encounters challenges due to its high hardness and chemical inertness. The three-step slurry-less Electrochemical Mechanical Polishing (ECMP) with NaCl electrolyte ensured efficient and damage-free polishing for 4H-SiC. However, the final step of slurry-less ECMP required sacrificing removal efficiency to prevent oxide layer breakdown and achieve an atomically smooth SiC surface. Additionally, the use of NaCl in practical industrial applications often resulted in equipment rusting easily. This study explored the substituting of a weak alkaline KOH electrolyte for NaCl in slurry-less ECMP, detailing oxidation mechanism of 4H-SiC. This alternative achieved an ultra-smooth surface without compromising the oxidation rate, laying a theoretical foundation for efficient slurry-less ECMP process.