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.
Highlights
The prepared chemical solution consisted of 3 wt% H2 O2, 0.01 M citric acid and 0.1 wt% BTA in deionized water (DIW)
EAF-Chemical–mechanical polishing (CMP) using an electrolytically ionized chemical solution was proposed to improve the efficiency of Abrasive-free CMP (AF-CMP)
The higher material removal rate (MRR) of EAF-CMP than that of AF-CMP may be due to active chemical reactivity and mechanical material removal
Summary
Chemical–mechanical polishing (CMP) is a semiconductor manufacturing process applied to planarize highly integrated devices [1,2,3] It uses both chemical reactions and mechanical material removal to planarize the surface of a semiconductor. A Cu CMP slurry contains abrasives, oxidizers, complexing agents, and corrosion inhibitors, which react chemically with Cu to create a chemically reacted layer on the surface of the Cu [9,10]. A high particle concentration and agglomerated particles are the main factors that cause scratches during CMP For this reason, several researchers have proposed the study of an abrasive–free CMP solution. The abrasive-free CMP solution has a high concentration of toxic chemicals to compensate for the low MRR. The effects of the oxidizer (H2 O2 ), complexing agent (citric acid), and corrosion inhibitor (BTA) concentrations in the electrolytically ionized CMP solution were examined
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