Modeling early failure in integrated circuit interconnect

A model based on the random electron-atom scattering is developed to charac terize the effects of defects and grain sizes on electromigration caused fa ilure in confined sub-micron metal interconnect lines. Our study shows that lines at sub-micron widths with a more uniform microstructure exhibit a gr eater consistency in time to failure. Taking mean time to failure and dispe rsion in time to failure as criteria, the simulator predicts that grain siz es in the 0.03-0.05 mu m range are optimal for 0.125 mu m wide Al alloy lin es. We also argue that the early failure mechanism associated with the miss ing metal defects is eliminated by using a homogeneous, fine-grained materi al. The uniformity of the structure results in a mono-modal failure distrib ution and contributes to increasing the built-in reliability of the interco nnect lines. (C) 2000 Elsevier Science Ltd. All rights reserved.