Understanding and eliminating defects in electroplated Cu films

Electrochemical deposition (ECD) is currently the only practical process for manufacturing Cu interconnections on silicon integrated circuits. However, this application is relatively new and some issues related to ECD defects remain to be resolved. One of the most important types of ECD defects consists of voids clustered together to form curved lines, referred to as "swirl defects". The swirl defect is a common phenomenon in ECD and is often associated with aged seed. Control experiments aimed in understanding the origin of this defect are discussed. A novel method to eliminate the defect is also presented.