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

摘要

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.