Observation of Joule Heating-Assisted Electromigration Failure Mechanisms for Dual Damascene Cu/SiO₂ Interconnects

Abstract

Failure mechanisms observed in electromigration (EM) stressed dual damascene Cu/SiO₂ interconnects trees were studied and simulated. Failure sites with ‘melt patch’ or ‘crater’ are common for test structures in the top metal layer, though the occurrence of such failure modes probably depends on the passivation layer thickness. Interconnects that were EM stressed for a short time and then stressed with increasing current to induce Joule heating in the line had similar failure sites to lines that were stressed to failure under standard EM conditions. This shows that some failure mechanisms during EM could be assisted by Joule heating effect.