Chemical mechanical polishing on silicon carbide using developed ceria composite abrasives and their synergistic polishing mechanism

The high hardness and chemical inertness of SiC hinder its efficient material removal and surface planarization during chemical mechanical polishing (CMP). Although Fenton-like reactions have been explored to promote SiC surface oxidation, conventional physically mixed catalyst-abrasive systems often suffer from poor dispersion and require external fields to enhance the catalytic reaction. The novelty of this work lies in the construction of integrated Cu_xO-CeO₂/Al₂O₃ composite abrasives, in which Cu_xO-CeO₂ Fenton-like catalysts are directly supported on commercial Al₂O₃ abrasives to couple catalytic oxidation and mechanical abrasion without external-field assistance. In SiC polishing, the composite abrasives deliver a material removal rate of 538.45 nm/h and a surface roughness of 0.629 nm over 50 × 50 μm², with a damaged layer thickness of 2.3 nm. CeO₂, owing to its low Mohs hardness and low elastic modulus, improves the wetting and frictional properties of the composite abrasives and promotes the formation of active Cu⁺ species. The Cu⁺ species catalyze the decomposition of H₂O₂ to generate highly oxidative ·OH radicals, which promote SiC surface oxidation and facilitate its subsequent removal by Al₂O₃ abrasives. This synergistic mechanism involving Fenton-like oxidation and mechanical abrasion was investigated by combining transmission electron microscopy and time-of-flight secondary ion mass spectrometry with electron paramagnetic resonance spectroscopy for the identification of reactive radicals.