Study on Chemical Mechanical Polishing of Single-Crystal Diamond with a Novel Nicotinic Acid–Hydrogen Peroxide Green Slurry

Single-crystal diamond (SCD) has the characteristics of a hard surface and stable chemical properties, making it difficult to achieve ultra-smooth and ultra-low-damage surface polishing using conventional polishing slurries. In this study, a novel green chemical mechanical polishing (CMP) slurry containing only hydrogen peroxide, nicotinic acid, silica (SiO2) abrasive particles and deionized water was developed to achieve ultra-smooth, ultra-low-damage (0.5 nm) and atomic-scale surface roughness (Ra 0.473 ± 0.035 nm) polishing of SCD. Additionally, the influence of diamond, silicon carbide and SiO2 abrasive particles on the surface quality of SCD after CMP was investigated by single-factor experiments. Based on XPS characterization, the mechanism of SCD CMP was revealed: the SCD surface was first oxidized to form C-O and C=O groups, and then these groups were removed under the mechanical action of SiO2 abrasives, ultimately achieving atomic-scale removal of the material.