Characterization and first-principles insights into the oxidation-removal mechanism of Si (0 0 0 1) and C (0 0 0 −1) surface of 4H-SiC in chemical mechanical polishing

Polarity-dependent CMP behavior of 4H-SiC Si-face and C-face is systematically investigated. • The C-face exhibits higher material removal rate and stronger oxidation tendency. • A thicker oxygen-rich reacted layer forms on the C-face during CMP. • Enhanced interfacial charge transfer promotes oxidant–surface interactions on the C-face. • First-principles calculations reveal the origin of polarity-dependent CMP behavior. Chemical mechanical polishing (CMP) of SiC is fundamentally limited by its high hardness and chemical inertness, as well as the pronounced polarity-dependent anisotropy between the Si-face (0 0 0 1) and C-face (0 0 0 −1). In this work, the intrinsic mechanism governing polarity-dependent oxidation and material removal of 4H-SiC is systematically investigated by combining CMP experiments, surface characterization, electrochemical analysis, and first-principles calculations.Under identical polishing conditions, the C-face exhibits a significantly higher material removal rate (1900 nm·h −1 ) and lower surface roughness (0.13 nm) compared to the Si-face (1000 nm·h −1 , 0.65 nm). Electrochemical results reveal faster oxidation kinetics on the C-face, which is further confirmed by the formation of a thicker oxide layer and enhanced oxygen-containing species. DFT calculations demonstrate that the C-face possesses higher surface energy, lower work function, and stronger charge transfer capability, leading to more favorable oxidant adsorption and interfacial reactions. These results reveal that the superior CMP performance of the C-face originates from its intrinsically enhanced electronic activity and oxidation-assisted removal capability. This work establishes a clear structure–property–performance relationship for polarity-dependent CMP of SiC and provides new insights for improving polishing efficiency and achieving wafer-level uniformity. Download: Download high-res image (234KB) Download: Download full-size image