Photothermal Chemical Mechanical Polishing: A Synergistic Mechanism for Fast and Atomic Level Surface Perfection

Abstract

Photo-assisted chemical mechanical polishing (PCMP) has emerged as a sustainable approach for fine polishing hard substrates. However, the light source of this approach is restricted to UV light, and the removal rate is relatively low. This study introduces a photothermal chemical mechanical polishing (PTCMP) technique adopting defect-engineered black nano-titanium dioxide (TiO₂) as the photothermal catalyst. The black TiO₂ demonstrates superior absorption across a broad optical range, enabling simultaneously photoinduced reactive oxygen species generation and localized photothermal heating under broadband light. This synergy in PTCMP is manifested with careful comparisons with ordinary TiO2 used in traditional PCMP under various illumination conditions. Mechanistic studies further reveal the dominant oxidative reactant is ·OH. Tunability in the polishing performance was demonstrated with varying parameters, achieving high material removal rate (MRR) and atomic-level surface roughness. This work provides an efficient method for achieving high-quality surfaces, paving the way for the sustainable processing of various substrates for advanced optics and electronics.