Environment-friendly electrochemical mechanical polishing using solid polymer electrolyte/CeO2 composite pad for highly efficient finishing of 4H-SiC (0001) surface

Abstract

Silicon carbide (SiC) is a promising material for use in high-performance power electronic devices. However, the SiC wafer is costly partly due to difficulties in machining the SiC surface. Furthermore, its prolonged polishing process requires massive amounts of resources, which increases the environmental impact of the wafer production process. Herein, we developed an environment-friendly and highly efficient electrochemical mechanical polishing (ECMP) method for 4H-SiC (0001) that does not require any liquid containing harsh chemicals and uses an ion-conductive composite pad consisting of a solid polymer electrolyte and CeO2 particles. The SiC surface finished using the proposed method was analyzed using X-ray analysis, Raman spectroscopy, atomic force microscopy, and X-ray adsorption fine structure measurements. A high material removal rate (MRR) of approximately 15 µm h−1, which is almost 10 times higher than that obtained by CMP, was achieved by the proposed ECMP method under the current density and mechanical condition of 25 mA cm−2 and 2.3 × 103 kPa min−1, respectively. The proposed method, which can remove surface damage and produce a smooth surface on the entire wafer scale with a high MRR without a liquid electrolyte, should prove to be advantageous for environment-friendly SiC wafer preparation.