Understanding the Initiation and Growth Variations of Electroless Cobalt Capping Layers at Different Features on Damascene Copper Interconnects

摘要

Thickness discrepancies of electroless cobalt alloy deposition on different copper interconnect features, due to initiation and growth behavior variations, were observed. This paper describes the impact of bath formulations, additives and process conditions on initiation and growth behavior of electroless cobalt thin films on features with different metal densities. Root causes for initiation and growth variations are discussed.