AES analysis of failures in Cu based electromigration test samples

Failures occurring in electromigration test of copper interconnects have be en characterized by electron backscatter diffraction (EBSD) and scanning Au ger microscopy (SAM). The Cu interconnects were 2 mum wide and 500 nm thick stripes on a Ta/TaN barrier. They are imbedded in trenches in a SiO2 layer on Si. The failure manifests as the appearance of voids with lateral dimen sion of some micrometers. By EBSD mapping, it could be verified that no sid ewall texture in the interconnect exist. Auger analysis clearly showed that the Ta/TaN barrier layer has not been destroyed at the site of electromigr ation failure. The interaction of the electron beam with small particles (a pproximate to0.5 mum) was modelled to understand the contribution of electr on scattering in the voids to the lateral resolution. (C) 2001 Elsevier Sci ence B.V. All rights reserved.