The excess noise in integrated circuit interconnects before and after electromigration damage

A detailed investigation is reported into the low frequency excess noise observed in metal films subjected to high unidirectional current densities. The resistance fluctuations due to the electromigration process are studied using three different methods; direct and alternating current probes and Fast Fourier Transform analysis of measured resistance changes with time. The noise observed in damaged and undamaged samples at low and high temperature are compared. It is concluded that 1/f noise is observed in samples with little electromigration activity and l/f^2 noise is observed when electromigration is proceeding strongly. This latter noise can be a small and well behaved quasi-equilibrium process but in damaged samples it can be large due to discontinuous resistance changes. No significant change has been observed in the white noise in such samples. © 1999 Elsevier Science Ltd. All rights reserved.