Atomic-scale surface of fused silica induced by chemical mechanical polishing with controlled size spherical ceria abrasives

Fused silica is widely used in precision optical devices for its excellent optical properties. However, it has hard and brittle nature, becoming a difficult-to-process material. This makes microscopic cracks left on the processed surface of silica induced by traditional mechanical processing methods. In this regard, it is a challenge to achieve an atomic-scale surface on silica. To overcome this challenge, nanometer CeO2 abrasives with uniform shape and size were prepared via a hydrothermal method. A novel chemical mechanical polishing (CMP) slurry is developed using the prepared CeO2 abrasives, Na2CO3 and deionized water, which is low-cost, non-toxic, and environmentally friendly. The surface roughness, Sa of fused silica after CMP is 0.093 nm with a scanning area of 20 × 20 μm2. To the best of our knowledge, it is the lowest surface roughness on silica after CMP. The CMP mechanism was investigated by X-ray photoelectron spectroscopy and infrared Fourier transformation. Under alkaline conditions, the abrasives interacted with the silica forming a CeOSi reaction product, through a chemical tooth action, which is significant to produce an atomic-scale surface on silica. These findings provide a new pathway to fabricate atomic-scale surface for a hard-brittle solid.