ELECTROMIGRATION FAILURE MODEL - ITS APPLICATION TO W PLUG AND AL-FILLED VIAS

For Al-Cu VLSI interconnects at tungsten (W) plug contact/via areas, a new electromigration (EM) failure model has been established. A serie s of experiments was performed to verify the proposed model using nove l test structures. This paper discusses the lifetime extrapolations us ing the model and experimental data which predicts that lifetimes of A I-Cu interconnects at use conditions are dominated by Cu drift, or inc ubation times. This paper also discusses EM experimental results obtai ned for the Al-filled via which is a promising candidate for replacing W plug vias due to requirements of process simplification and cost re duction in multilevel metallizations. EM failure distributions from Al -filled vias show large standard deviations. This observation is expla ined through extensive failure analysis of EM-failed specimens. The ap plication of the established EM model to Al-filled vias is discussed. (C) 1998 Elsevier Science S.A. All rights reserved.