THE APPLICABILITY OF LOGARITHMIC EXTREME-VALUE DISTRIBUTIONS IN ELECTOMIGRATION INDUCED FAILURES OF AL CU THIN-FILM INTERCONNECTS/

In electromigration failure studies it is in general assumed that elec tromigration induced failures may be adequately modelled by a log norm al distribution. Further to this it has been argued that a log normal distribution of failure times is indicative of electromigration mechan isms. We have combined post processing of existing life-data from Al/C u+TiW bilayer interconnects with our own results from Al/Cu interconne cts to show that the Log Extreme Value distribution is an equally good statistical model for electromigration failures, even in cases where grain size exceeds the line width. The significance of such a modellin g is particularly apparent in electromigration failure rate prediction .