Defect-Engineered MnO2 as Catalyst for the Chemical Mechanical Polishing of Silicon Carbide Wafer

Abstract

Chemical mechanical polishing (CMP) of SiC wafer is challenging due to its extreme hardness and inertness. Catalyst assisted CMP is a cost-effective approach to increase material removal rate (MRR) without sacrificing surface quality. Herein, oxygen-deficient α-MnO2 was prepared by mechanochemical synthesis and the effect of catalyst physiochemical structure on the CMP performance of Si-face SiC wafer was systematically studied. The addition of 1% α-MnO2 catalyst increased MRR by 38.8% to 1.11 μm h−1, much higher than commercial γ-MnO2. The synergy of phase structure, oxygen vacancy and surface area & porosity contributed to the high catalytic activity. α-MnO2 is an outstanding oxidation catalyst due to its stable framework, large tunnel size, rich surface area and porosity, which can facilitate the adsorption, activation and transfer of guest species and intermediates and therefore affects the reaction pathway and reaction kinetics. Mechanochemical synthesis generates nano MnO2 particles with rich oxygen vacancies. The presence of more surface oxygen vacancies can improve oxidizing activity of MnO2 catalyst, facilitating the oxidation of C species on wafer surface. The use of defect-engineered α-MnO2 catalyst is promising for overcoming the present bottlenecks of long processing time and high cost of current CMP of SiC wafer.