Optimization of NH3 plasma surface treatment using Cu silicide formation for EM/SM improvement

Abstract

Authors investigated optimization of NH3 plasma surface pre-clean treatment using Cu silicide formation in order to improve electromigration (EM) and stressmigration (SM). NH3 plasma treatment removed Cu oxide but also led to reduced Cu silicide at the Cu/capping layer interface. Despite Cu oxide removal, EM/SM was observed to degrade due to the reduction of Cu silicide. It was critical to restore Cu silicide at the interface when employing NH3 plasma treatment to improve EM/SM.