Obtaining Atomically Smooth 4H–SiC (0001) Surface by Controlling Balance Between Anodizing and Polishing in Electrochemical Mechanical Polishing

Abstract

Single-crystal 4H–SiC is a promising next-generation semiconductor material for high-power and low-loss power devices. Electrochemical mechanical polishing (ECMP) is a very promising polishing technique for the manufacture of SiC wafers owing to its high efficiency and low cost. In this study, the effects of the balance between the anodic oxidation rate and the polishing rate of the oxide layer on the polishing performance of slurryless ECMP were studied in an attempt to obtain an atomically smooth surface efficiently. The polishing performance of ECMP was evaluated from the viewpoints of surface roughness, residual oxide, and material removal rate. It was found that the balance between the anodic oxidation rate and the polishing rate of the oxide layer strongly affects the surface roughness; the polishing rate of the oxide layer should be greater than the anodic oxidation rate to obtain an atomically smooth surface. By controlling this balance at a current density of 10 mA/cm2, we were able to decrease the surface roughness of a diamond-lapped 4H–SiC (0001) surface from Sq 4.290 to 0.577 nm and obtained a high material removal rate of about 10 μm/h. This study provides a promising way of obtaining atomically flat surfaces by slurryless ECMP.