Atomic surface of quartz glass induced by photocatalytic green chemical mechanical polishing using the developed SiO2@TiO2 core–shell slurry

Abstract

High-performance devices of quartz glass demand an atomic surface, which induces a challenge for chemical mechanical polishing (CMP) with a high material removal rate (MRR). Moreover, traditional CMP usually employs toxic and corrosive slurries, leading to the pollution of the environment. To overcome these challenges, a novel green photocatalytic CMP is proposed. In the CMP, SiO₂@TiO₂ core–shell abrasives were developed, and the CMP slurry included the developed abrasives, sodium carbonate, hydrogen peroxide and sorbitol. After photocatalytic CMP, the surface roughness S_a of quartz glass is 0.185 nm, with a scanning area of 50 × 50 μm², and the MRR is 8.64 μm h⁻¹. To the best of our knowledge, the MRR is the highest on such a big area of atomic surface for quartz glass. X-ray photoelectron spectroscopy reveals that SiO₂@TiO₂ core–shell abrasives were used as photocatalysts motivated by simulated solar light, generating electrons and holes and producing hydroxyl radicals through hydrogen peroxide. As a result, OH⁻ could combine with Si atoms on the surface of quartz glass, forming Si–OH–Si bonds. Then the formed bonds were removed based on the balance between chemical and mechanical functions. The proposed CMP, developed SiO₂@TiO₂ abrasives and slurry provide new insights to achieve an atomic surface of quartz glass with a high MRR.