MD simulation of chemically enhanced polishing of 6H-SiC in aqueous H₂O₂

Abstract

Chemical enhanced polishing (CEP) is a widely employed final process for achieving precise surface shaping and planarization of semiconductor wafers. However, determining the chemical effect involved in material removal through experimental means is extremely challenging. In this study, we conducted reactive force field (ReaxFF) molecular dynamics (MD) simulations to gain insight into the chemical effects of CEP using an aqueous hydrogen peroxide (H2O2) diamond suspension as a polishing medium for 6H-SiC single crystals. The inclusion of aqueous H2O2 resulted in the formation of Sisingle bondOsingle bondH and Csingle bondOsingle bondH species, which are comparatively easier to remove through mechanical abrasion. Furthermore, an increase in H2O2 concentration was found to enhance the material removal. The MD simulations also revealed that the chemical effects on the Si-face of 6H-SiC were more pronounced than those on the C-face due to the generation of a greater number of Sisingle bondO species and the favourable atomic structure of the Si-face for chemical removal. The results showed that the material remove rate on the Si-face is greater than that on the C-face during polishing, aligning with the findings from MD simulation. Furthermore, a systematic experimental study was carried out to examine the influence of various conditions on material removal rate and surface quality in both polishing and lapping processes.