Investigation on Pad Surface Conditioner to Control Dishing Amount in Cu Damascene Process

Abstract

In the Cu damascene chemical mechanical planarization (CMP) process, dynamic interaction of wafer and pad surfaces is a mechanism of material removal to prepare flat layer on wafer surface. During the interaction, chemical and mechanical effects are working at the same time to get the desired surface. Because, polishing pad has elastic characteristic, pad asperity in contact with wafer surface might be deformed and chemically reacts only at pattern trench area where Cu is filled. Thus, a resulted phenomenon called ‘dishing’ occurs. To control Cu pattern dishing, in present study, we observed the dishing amount variation by modifying polishing pad surface which was dressed by pad conditioners in different design. It is resulted that the number of contact between pad asperity and wafer surface is a key factor to suppress dishing phenomenon during Cu damascene CMP process.