Interconnect Failure due to Cyclic Loading

The damage generated by AC currents at 100 Hz in interconnects has been studied and compared with mechanical fatigue damage in thin films. The nature of the damage under the two loading conditions is qualitatively similar, supporting the idea that the AC current damage comes from mechanical cycling due to temperature swings on the order of 100 K from Joule heating in the interconnects. In both cases, the damage forms as surface wrinkles within single grains grow in amplitude and extent with time. The possible threat to the reliability of microelectronic and microelectromechanical systems is further escalated by the observation that soft encapsulation layers do nothing to retard the formation of the damage.