Electromigration in Al thin films induced by surface acoustic waves: Application to imaging

The propagation of a high amplitude surface acoustic wave in an Al thin fil m induces a large-scale electromigration phenomenon resulting in a permanen t etching of the acoustic field in the film. The etched patterns depend on the time of propagation and on the acoustic characteristics. Preliminary ob servations of a few grooved structures in Al films have been performed by d ifferent techniques. A first explanation of this phenomenon based on dynami cal Grinfeld instabilities is proposed. By providing permanent pictures of acoustic fields emitted by transducers, this effect could be used to perform imaging of surface acoustic wave propa gation.