Reliability mechanisms and lifetime extrapolation methods for scaled interconnect technologies

Abstract

We review our current understanding of the degradation mechanisms in scaled interconnects. Concerns on the applicability of today's reliability evaluation methods are expressed. Regarding electromigration (EM), both scaling line dimensions and using mechanically weaker intermetal dielectrics (IMDs) have a negative impact on its performance, where remedial measures to overcome this downward trend are discussed. With aggressively scaled barriers, we also show that EM test methodology adaptation towards constant voltage testing might be needed. Regarding dielectric reliability, we quantify the reliability degradation induced by both k-value and spacing reduction. Also, we review the current understanding on lifetime models used for predicting high field data to lower fields. Both for copper and dielectric reliability, we highlight that the development of ways to account for process variability during lifetime prediction will become key in the future.