IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electronics Tuesday Sessions
       Session EL-TuP

Paper EL-TuP27
Effect of Interfacial Underlayers on Electromigration in Epitaxial Cu(001) Lines

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Electronic Materials Poster Session
Presenter: R. Goswami, Rensselaer Polytechnic Institute
Authors: R. Goswami, Rensselaer Polytechnic Institute
H.S. Goindi, Rensselaer Polytechnic Institute
H. Kim, Rensselaer Polytechnic Institute
M.J. Frederick, Rensselaer Polytechnic Institute
G. Ramanath, Rensselaer Polytechnic Institute
C.-S. Shin, University of Illinois, Urbana
I. Petrov, University of Illinois, Urbana
J.E. Greene, University of Illinois, Urbana
Correspondent: Click to Email
The effects of grain size, preferred orientation, and interfacial layers on electromigration (EM) in Cu lines are not yet well understood. In order to isolate the effect of the underlayer and grain structure, we investigate the EM behavior of epitaxial Cu(001) lines on Ta, TaN, and TiN underlayers. Accelerated EM tests were carried out on 2-µm-wide lines with a 3.5 MA/cm@super 2@ current density at temperatures between 200-300 °C. Cu(001) lines on TiN or TaN shows up to a factor-of-10 higher mean-time-to-failure when compared with those on Ta. The superior EM resistance of lines on nitride underlayers correlates with a higher crystal quality--measured by X-ray diffraction--of the Cu epilayers. This correlation is also observed in preliminary experiments of Cu films with slightly different epilayer-quality, deposited on the same underlayer. The activation energy of EM-induced failure of Cu lines on the nitrides is ~0.9 eV, which is significantly higher than the value of ~0.2 eV, observed for Cu(001) on Ta. Our results suggest that orientation inheritance is an important factor that determines the EM lifetime. Based upon these results, we discuss the EM failure mechanism in the context of epitaxial film microstructure, Cu-underlayer interface, and failure morphology revealed by scanning and transmission electron microscopy (SEM and TEM)measurements.