Damaging of metallization layers by high power surface acoustic wave fields

摘要

Similar to interconnection lines in integrated circuits patterned metallization structures are used as electrodes and reflecting elements in surface acoustic wave (SAW) devices. As electromigration is known to be a damaging mechanism in interconnects also the metallization of SAW devices tends to be degraded under high power conditions. Corresponding to the source of degradation, namely the elastic waves, the latter is called acoustomigration. Aim of this work is an approach to understand damage mechanisms by corresponding loading conditions and failure occurences in the metallization. Our work is focused on in situ experiments with standing SAWs combining electrical measurements and different microscopic investigations (OM, SEM, FIB), detailed consideration of SAW stress field structure in connection with model experiments, and making use of the route of Cu technology. First results of a comparative study of fully metallized Al and Cu areas supporting high amplitude travelling SAWs are presented showing different damaging features, similar to those known from electromigration.