Failure Mechanisms of W/TiN/Ti Metal Lines under High Current Stressing

Current-induced morphological changes of W/TiN/Ti metal lines under voltage stressing in the range of 1.2–20 V were studied for 50- and 100-nm-wide lines. The relationship between the median time to failure and current density showed a power law dependence with two different exponent values depending on the applied current density level, irrespective of the line width. Self-heating-assisted electromigration, and melting and agglomeration are suggested as the dominant mechanisms in the low- and high-current-density regions, respectively.