Atomistic Insights into Cu Chemical Mechanical Polishing Mechanism in Aqueous Hydrogen Peroxide and Glycine: ReaxFF Reactive Molecular Dynamics Simulations

To clarify the chemical mechanical polishing (CMP) mechanism of Cu in aqueous hydrogen peroxide and glycine, we developed a ReaxFF reactive force field to describe the interaction between Cu, slurry (H₂O, H₂O₂, and glycine), and the silica abrasive. Based on this force field, we used molecular dynamics simulations to illustrate the chemistry at the Cu/silica abrasive interface and Cu atom removal mechanism during the Cu CMP process. Our results indicate that H₂O easily chemically adsorbs on the Cu surface, and H₂O₂ can dissociate into hydroxyl radicals, forming Cu-OH. Besides, the OH-terminated silica surface can chemically interact with the Cu substrate, leading to the formation of Cu-OH on the Cu substrate. During the CMP process, Cu atoms on the substrate are effectively removed due to the mechanical sliding process-induced chemical reactions, including mainly three removal pathways: shear-induced glycine-adsorbed Cu atom removal process, shear-induced OH-adsorbed Cu atom removal process, and shear-induced Cu atom removal process due to the formation of interfacial Cu-O-Si bridge bonds. These results provide atomistic insights into the chemical reactions under mechanical effects in the Cu CMP process, thus helping the slurry design and process parameter optimization.