Electromigration characteristics of via chains for multilayered metallization

Electromigration phenomena associated with vias of multilayered TiW/AlCuSi/TiW metallization were studied. It was found that the resistance change due to stress current of the via chain was different from that of the metal line. The activation energy related to the mean time to failure (MTTF) of the via chain was much larger than that of the metal line. The alloying reaction between Al and TiW dominated the lifetime of the via chain. The TiW layer, which blocked Al flow, played an important role in the high electromigration resistance of the via