Effect of pulsed electric fields on dielectric breakdown in Cu damascene interconnects

Abstract

We investigated the effects of pulsed electric fields on dielectric breakdown in Cu damascene interconnects. Among the DC, unipolar, and bipolar pulse conditions that were examined, the dielectric lifetime was longest under the bipolar condition because Cu contamination was suppressed due to backward Cu migration. Under the unipolar pulse condition, the dielectric lifetime was enhanced over that under the DC condition, as the pulse frequency increased. These results suggest that the intrinsic breakdown of dielectrics, in addition to Cu contamination, significantly contributes to their reliability. The bond breakdown probability decreased as the unipolar pulse width decreased below the threshold value.