Abrasive-free surface finishing of glass using a Ce film

Abstract

A novel form of abrasive-free polishing is described, using Ce film deposited on a polishing pad by vacuum evaporation. Polishing using metallic films other than Ce, such as Al and Cu, generates defects on the glass surface with almost negligible material removal rates (MRRs), whereas Ce film with deionized (DI) water achieves smooth, scratch-free surfaces with noticeable MRR. If DI water is not supplied to the pad, there is significant deterioration in polishing performance. MRR increases with greater thickness of Ce film, and extremely smooth surface with sub-nanometer roughness is achieved using Ce film of thickness 2.5 μm. Polishing performance is dependent on conditions such as pad rotation rate and polishing pressure. By adding potassium hydroxide (KOH) to the polishing solution, the MRR almost matches that obtained with conventional abrasive polishing, but achieves ultra-smooth surface finish (Ra: 0.388 nm). The polishing method presented here uses approximately 94% less Ce compared with conventional abrasive polishing, thereby dramatically reducing consumption of this valuable rare earth element.