Electromigration characterization of damascene copper interconnects using normally and highly accelerated tests

We have completed a set of experiments on damascene Chemical Vapor Depositi on Copper (CVD-Cu) interconnects using Wafer Level and Package Level Reliab ility (WLR and PLR) tests. Two line widths have been extensively characteri zed : w=4 and 0.6 mu m For both line widths, the activation energy values e xtracted using WLR and PLR data are in good agreement demonstrating that th e active diffusion paths remain the same over the wide range of used measur ement conditions : Ea=0.65eV for w=4 mu m, Ea=0.7-0.8eV for w=0.6 mu m. Mor eover, Scanning Electron Microscope (SEM) observations gave evidences of gr ain boundary diffusion in spite of Ea experimental values lower than the re ference values of the literature. (C) 2000 Elsevier Science Ltd. All rights reserved.