Fast Thermal Cycling-Enhanced Electromigration in

Multilevel interconnects used in power ICs are sus- ceptible to short circuit failure due to a combination of fast thermal cycling and electromigration stresses. In this paper, we present a study of electromigration-induced extrusion short-circuit failure in a standard two level metallization currently used in power ICs and in particular the effect of fast thermal cycling on the subse- quent electromigration lifetime. A special test chip was designed, in which the electromigration test structure is integrated with a heating element and a diode as temperature sensor in order to gen- erate fast temperature swings and to monitor them. Experimental results showed that with the introduction of fast thermal cycling as a preconditioning, the electromigration lifetime is significantly re- duced. We observed that the reduction of the electromigration life- time depends on the stress time, temperature range and the min- imum temperature. Electromigration simulations using a two-di- mensional simulator confirm the extrusion short circuit as failure mechanism.