A NEW TECHNIQUE TO CHARACTERIZE THE EARLY STAGES OF ELECTROMIGRATION-INDUCED RESISTANCE CHANGES AT LOW CURRENT DENSITIES

One of the promising tools to study electromigration (EM) in metal lin es is the high resolution resistance measuring (HRRM) technique. Since the resistance is sensitive both to structural and geometrical change s in a metal line, this technique is very useful to study the early st ages of EM-induced damage. However, with a conventional HRRM-technique it is impossible to separate resistivity from geometrical variations. Here, a new analyzing technique is presented which is able to separat e these two contributions during EM-experiments at low current densiti es. It is found that only during the very first stage of EM resistance variations are due to resistivity variations. On the contrary, resist ance variations Delta R/R>2000ppm are mainly caused by a decrease in t he cross section of the metal line. Copyright (C) 1996 Elsevier Scienc e Ltd