Material transport in Al-metallizations of power-loaded SAW structures

Material transport in Al/Ti-finger electrodes on LiNbO3 substrates of power-loaded surface acoustic wave (SAW) structures were investigated under microscopic observation with respect to stress-induced material transport. Additionally, investigations were carried out before and after SAW loading during lifetime experiments. For the experiments, a special power SAW test structure was applied realizing travelling SAWs. The results show that the microstructure of the electrodes was damaged by void and hillock formation even at moderate input power. This changes the electrical and acoustical properties of the SAWstructures irreversibly. The logarithmic time-to-failure (TTF) of damaged SAW structures depends linearly on loading time and rf power.