Material Removal Characteristics of Abrasive-Free Cu Chemical-Mechanical Polishing (CMP) Using Electrolytic Ionization via Ni Electrodes

Abstract

Recently, various efforts have been made to reduce the environmental burden caused by semiconductor manufacturing by improving the process efficiency. Chemical mechanical polishing (CMP), which is used to planarize thin films in semiconductor production, has also been studied to improve its efficiency by increasing the material removal rate (MRR) while reducing its environmental burden. Previous studies have been conducted to electrolytically ionize chemical solutions used in abrasive-free CMP for improving the MRR. In this study, we analyzed the change in the chemical solution according to the variation in voltage applied to the nickel (Ni) electrode in abrasive-free Cu CMP and studied the tribological material removal characteristics. The experimental results revealed that electrolytic ionization of the chemical solution for abrasive-free CMP increases the amount of dissolved oxygen (DO). The static etch rate of the Cu thin film and MRR in CMP increased as the voltage applied to the Ni electrode increased. The frictional force and temperature during CMP also increased as the applied voltage increased. Therefore, the increase in MRR caused by the increase in the applied voltage in abrasive-free Cu CMP using electrolytic ionization is plausibly caused by the chemical reaction between the dissolved oxygen in the chemical solution and Cu.