Compound mechanical and chemical-mechanical polishing processing technique for single-crystal silicon carbide

In this study, a novel polishing approach was proposed, that combined nanodiamond mechanical polishing (MP) with silicon dioxide chemical-mechanical polishing (CMP) to achieve the high-quality and high-efficiency processing of single-crystal silicon carbide (SiC). A compound-polishing experiment was conducted to evaluate the material-removal rate (MRR) and surface roughness. The results showed that MP had a high MRR and poor surface quality, whereas CMP obtained a better surface quality; however, its MRR was low. Using surface roughness as the research target, the relationship between MP and CMP was then obtained through a combined process optimisation analysis. Consequently, the compound-polishing method was revealed in terms of the material-removal mechanism, with the surface quality being related to the formation rate of the oxidation reaction layer. Finally, the effectiveness of the compound-polishing method was experimentally verified. For the same surface accuracy, the polishing efficiency of this method improved by 30 % compared to that of CMP. The results proved the proposed compound-polishing approach to be beneficial for enhancing the machining accuracy and efficiency of a single-crystal SiC substrate.