PROJECTING INTERCONNECT ELECTROMIGRATION LIFETIME FOR ARBITRARY CURRENT WAVE-FORMS

We propose a vacancy relaxation model which predicts that dc lifetime is Adc(T)/Jm, pulse dc (arbitrary unidirectional waveform) lifetime is [Formula omited], pure ac lifetime is [Formula omited] and ac-plus-dc-bias lifetime is [Formula omited] for all waveforms and all frequencies above 1 kHz. These predictions are verified by experiments and significantly raise the projected lifetimes beyond the widely assumed [Formula omited]. The pure ac lifetimes of aluminum interconnect are experimentally found to be more than 103 times larger than dc lifetime for the same current density. In addition, ac stress lifetimes are observed to follow the same dependences on current magnitude and temperature, for T < 300°C, as the dc stress lifetime. © 1990 IEEE