Reliability of dual-damascene local interconnects featuring cobalt on 10 nm logic technology

Abstract

This paper discusses the reliability of a new metallization scheme for 10nm back end of line (BEOL) local interconnect. Electromigration (EM) and time dependent dielectric breakdown (TDDB) on cobalt fill interconnects are investigated. Significant innovation in process manufacturing are delivered to meet the reliability challenges of technology scaling. Electromigration time to failure is observed to be at least four orders of magnitude higher for Co fill interconnects compared to Cu alloy metallurgy. Intrinsic TDDB reliability for Co/low-k ILD meets the expectations and surpasses the capability of Cu/low-k ILD systems with E-field acceleration factor of ~5 cm/MV using E-model fit. Wafer level stress induced voiding reliability on Co shows superior intrinsic properties with respect to Cu.