The effects of alternating current on deformation and failure of 60 nm-thick nanocrystalline cu lines

In this paper, the thermal fatigue properties of small scale copper structures on silicon substrate under cyclic thermo-mechanical loads introduced by alternating current have been investigated by in situ observation the evolution of fatigue damage. The effects of alternating current (AC) on the deformation and failure behavior of 60-nm-thick nanocrystalline (NC) Cu lines were studied. Experimental results revealed the current-density dependent failure mechanism of NC Cu lines. Under low current density condition, the failure process was dominated by stress controlled fatigue mechanism of grain extrusion. Under high current density condition, however, the failure mode was Joule-heating dominated thermal activated process.