A study of chemical products formed on sapphire (0001) during chemical-mechanical polishing

A study of chemical products formed on sapphire (0001) during chemical-mechanical polishing is presented. The results demonstrated that the formation and removal of chemical products both proceeded from the hexagonal close-packed sapphire Al-O layers described as atomic terraces, and the material removal rule of sapphire (0001) during chemical-mechanical polishing is the regular removal of chemical products formed from the atomic terraces, which were successfully characterized by AFM with super-sharp scanning probes. Besides, we also found that the surface with screw dislocations could not be polished completely by CMP due to the crystal distortion energy, and a hard polishing pad could remove scratches more effectively than a soft one.