Study on Chemical Mechanical Polishing Performances of Sapphire Wafer (0001) Using Silica-Based Slurry

Abstract

In this paper, the chemical mechanical polishing (CMP) mechanism of silica-based slurry on sapphire wafer was analyzed. The influences of size and abrasive concentration of silica-based slurry on the material removal rate (MRR) of (0001) sapphire wafer were investigated, respectively. Furthermore, the effect of chemical agents on MRR was mainly studied. It was found that most alkali metal salts and halogen salts except for fluoride salts can be used as polishing promoting agents to increase MRR. The promotion effect of monovalence cations to MRR decreases with the increase of atomic number. The MRR strongly relies on the kind of alkaline agents used in slurries. During the process of sapphire CMP, no chelating reaction occurred when the chelating agent was added to the silica-based slurry. The double-polished sapphire wafer has a transmittance of 86% to visible light and can be used as the optical window for the screen of smart mobile phones and so on.