Via electromigration performance of Ti/W/Al-Cu(2%) multilayered metallization

Via electromigration (EM) performance of Ti/W/Al-Cu(2%) metallization is reported for 1.2-μm vias defined in 1.0 μm of interlevel oxide. Using a Kelvin-contact stressing structure, the via resistance was monitored independently of the EM-induced damage which occurs in the metal leads servicing the via. Even for EM-induced resistance rises of up to 270% in the metal leads, the vias remained stable with via resistance rises of less than 20%. This indicates that the metal stripes exhibit electromigration wearout well before the vias fail. These results were independent of the direction of current flow in the via