Electron back scattered diffraction study of acoustomigration damage in Al/Ti metallization for SAW devices

The correlation between the microstructure of a 340 nm thick Al metallizations deposited on a thin Ti adhesive layer and damage due to acoustomigration was investigated. For this reason, the {1 1 1} textured metallization was acoustically loaded by gradually increasing rf power up to 3.6 W. The hillock and void formation during load experiments was mostly detected at such grain boundary triple junctions, which consist of two grain boundaries with misorientation angles <30° and one grain boundary with a misorientation angle >30°. The results were achieved by means of scanning electron microscopy, electron back scattered diffraction, and focused ion beam technique.