An electrochemical method of suppressor screening for Cu plating in sub-100 nm lines

Abstract

A two-step transient method was developed to electrochemically screen suppressor molecules toward the applications in Cu plating chemistry for narrow trenches. The first potential transient with full amount of suppressor was acquired to simulate the potential applied on the wafer, which is largely determined by the plating of the field region on the wafer. A second current transient experiment with the potential controlled by the transients acquired in the first experiment is used to mimic the plating at different locations across the wafer. When different fractional amounts of suppressor are injected into the second experiment, the current transients acquired thereof simulate the plating rate in the trench structure. A slower super filling rate at higher plating current was well predicted by the transient method and was confirmed by filling experiments. A good qualitative correlation was also observed between the current transients and the filling performance of different suppressors. © 2014 The Electrochemical Society. All rights reserved.