Electrolytically Ionized Abrasive-Free CMP (EAF-CMP) for Copper

Abstract

Chemical–mechanical polishing (CMP) is a planarization process that utilizes chemical reactions and mechanical material removal using abrasive particles. With the increasing integration of semiconductor devices, the CMP process is gaining increasing importance in semiconductor manufacturing. Abrasive-free CMP (AF-CMP) uses chemical solutions that do not contain abrasive particles to reduce scratches and improve planarization capabilities. However, because AF-CMP does not use abrasive particles for mechanical material removal, the material removal rate (MRR) is lower than that of conventional CMP methods. In this study, we attempted to improve the material removal efficiency of AF-CMP using electrolytic ionization of a chemical solution (electrolytically ionized abrasive-free CMP; EAF-CMP). EAF-CMP had a higher MRR than AF-CMP, possibly due to the high chemical reactivity and mechanical material removal of the former. In EAF-CMP, the addition of hydrogen peroxide (H2O2) and citric acid increased the MRR, while the addition of benzotriazole (BTA) lowered this rate. The results highlight the need for studies on diverse chemical solutions and material removal mechanisms in the future.

Keywords

• chemical–mechanical polishing (CMP)
• ionization
• abrasive-free slurry
• copper (Cu)