Effect of multiple via layout on electromigration performance and current density distribution in copper interconnect

Downstream Electromigration (EM) was studied on different multiple via structures. Structures with more via gained better EM performance improvement. Failure analysis showed different EM failure modes on these structures. Finite element analysis is applied to find out the current density profiles and their variation between these structures. Resistance increases due to EM induced void are also simulated and found to be dependent on size and location of void. The different EM results of these multiple via structures are explained with the current density results and the different diffusion patterns found.