Modeling electromigration failures in TiN/Al-alloy/TiN interconnects and TiN thin films

Electromigration characteristics, especially resistance oscillations, of TiN/Al-alloy/TiN multilayered interconnect and the failure mechanism of a TiN barrier layer have been studied. A model has been developed for the linewidth dependence of the multilayered structure. The experimental results show that the failure observed in TiN was not caused by electromigration, instead it was due to thermomigration caused by a temperature gradient. The activation energy of this process was found to be 1.5 eV. In order to obtain a 10-year lifetime, the hottest spot in the TiN film must be kept below 408/spl deg/C. This suggests that TiN may safely conduct 2.4/spl times/10/sup 7/ A/cm/sup 2/ for the typical thermal impedance of a hot spot.