Reservoir modeling for electromigration improvement of metal systems with refractory barriers

Metal ion reservoirs in a Ti-AlCu-TiN metal system with W vias have been shown to increase electromigration lifetimes in barrier metal systems. In this study, it is empirically shown that EM lifetime increase is related to the natural-log of reservoir length in a constant width line. In this process, where vias do not penetrate the barrier, the number of vias, via spacing, and metal overlap do not play a significant role in defining EM lifetime. The results are thought to apply to any barrier metal system, assuming the via does not penetrate the barrier and contact the AlCu or Cu main conductor.