Study on the Mechanism of Electrochemical Anodization for the Fixed-Abrasive Polishing of 4H-SiC

Silicon carbide (SiC), as a core material for third-generation semiconductors, yet its extreme hardness and chemical inertness present significant challenges for polishing. This study investigated the mechanism of electrochemical anodic oxidation on 4H-SiC and analyzed the effects of electrolyte type, concentration, and potential. Through orthogonal experimental design, it enhanced the material removal rate(MRR) in electrochemical fixed-abrasive polishing (EFAP). The results indicate that the anodic oxidation reaction mechanism occurring on the SiC surface involves the cleavage and hydroxylation of Si-C bonds, as well as the formation of Si-O and C-O bonds. 20 wt% NaNO 3 solution exhibited the highest current density, with its peak occurring near 8 V, and the oxygen content on the SiC surface reaching 29.5%. Under optimal process conditions, the SiC surface was polished from an initial roughness ( R a ) of 10 nm to 0.34 nm, with a stable MRR of 169 nm min −1 . Additionally, EFAP effectively improves the overall flatness of the substrate and eliminates subsurface defects. The study demonstrates that this technique, by balancing mechanical removal and electrochemical softening effects, effectively improves the surface quality of SiC substrates and provides an innovative solution for the efficient processing of hard and brittle materials.