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.

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

“…Figure 3 illustrates the MRRs when an abrasive-free CMP solution was electrolytically ionized at 30 V using the stainless steel and Ni electrodes. In accordance with Park et al [ 17 ], the MRR was 303.9 nm/min when a voltage of 30 V was applied to the abrasive-free CMP solution using the SUS electrode. Ni is known to have a higher conductivity than SUS; therefore, electrolytically ionizing an abrasive-free CMP solution more efficiently seems possible.…”

“…The average frictional forces were 0.100, 0.105, 0.110, and 0.116 kN at 0, 10, 20, and 30 V, respectively, and the frictional force increased as the applied voltage increased. Compared to general abrasive-free CMP, the friction force in abrasive-free CMP that uses an electrolyzed chemical solution tends to be similar to that obtained by Park and Lee [ 17 ].…”

“…In addition, surface chemical analysis revealed that the electrolytically ionized slurry generated more oxidized copper than the general slurry, and using UV-vis spectroscopy, the electrolytic ionized slurry was confirmed to generate more ·OH radicals. Based on the research by Lee et al [ 16 ], Park and Lee [ 17 ] introduced electrolytically ionized abrasive-free Cu CMP. In their study, stainless steel was used as the electrode material, and an AC power supply was used to apply a voltage (30 V).…”

Monodispersion of SiO2/CeO2 Binary Nano-Abrasives with Adjustable Size in Chemical Mechanical Polishing Performance of Copper

“…The chemisorbed Cu-BTA composite layer formed by BTA was able to inhibit the excessive dissolution of Cu ions and reduce the corrosion effect in the grooves of Cu sheet. 8 However, BTA is also one of the main objects of Cu-CMP post-cleaning removal. 9 Yang et al 10 proposed to replace BTA with biocompatible polyethylene pyrrolidone (PVP) in polishing slurry.…”