Impact of side reservoir on electromigration of copper interconnects

Side reservoir can improve electromigration (EM) lifetime of copper interconnects. In this work, finite element method (FEM) simulations for interconnect structures with cathode end-of-line reservoir and side reservoir respectively have been conducted to study the side reservoir effects on EM lifetime. It is demonstrated that side location is most likely to have void failure and side reservoir can move the maximum atomic flux divergence (AFD) sites from above via location to side reservoir location so that it can improve EM lifetime. The root cause for this improvement is that side reservoir can impede stress built-up at above via location.