Pulsed Current Electromigration Failure Model

The electromigration failure rate in conductors carrying rectangular current waveforms is a function of temperature, stress current density, period, and duty cycle or total on-time. This study used constant current lifetests to determine activation energy and current density acceleration, and correlated this lifetime to that obtained during pulsed current stress. A time-average current density, JDC, has been determined in an Al1%Si metal system for current densities between 0.3 and 2.0 MA/cm2 and duty cycles between 20 and 100% at 500 kHz and 175°C. The median time-to-failure for a rectangular waveform was best expressed as t50 = Ao(JDC)-n eEA/KT for a duty cycle between 20 and 100% at 500kHz and 175°C.