In-situ preclean run path impact on selective cobalt cap deposition and electromigration

Abstract

This paper will provide an in-depth study of the run path impact an in-situ thermal Hydrogen preclean performed on a Copper interconnect has on the selective Cobalt cap deposition process. A loss in selective Cobalt cap thickness was observed with a wafer order dependence which resulted in a degradation in Electromigration performance. With Electromigration lifetimes dropping due to interconnect scaling, it is important to maintain and improve the Electromigration reliability of devices as we move to smaller nodes. By altering the wafer run path through a multi-chamber process tool, we were able to recover the loss of Cobalt selective deposition and thickness.