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

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