Effect of the Electrode Layer on the Deposition of AlN for Biosensors

© 2017, Springer International Publishing Switzerland. In the development of thin film bulk acoustic resonators (FBAR) based on AlN piezoelectric thin films for biosensing applications, a metallic electrode below the piezoelectric film is not only an essential element for the performance of these devices, but it also influences the structure and properties of the AlN film. The present study addresses the effect of an Al electrode, which also serves as an adhesion interlayer, on the final characteristics of Al/AlN films intended for FBAR biosensors. For this purpose, various single Al and Al/AlN thin films were deposited on 304L substrates by radio frequency (r.f.) magnetron sputtering. The selected processing parameters were deposition time and applied power for the Al layers. For the case of the single Al films, the deposition time had a stronger influence than the applied power in the ranges studied. Longer deposition times, regardless of the applied power, led to the formation of rougher, thicker films. The structure of the Al films in turn strongly affected that of the final Al/AlN coatings, particularly their morphology and phase selection. The present results highlight the importance of the metallic electrode structure in the development of acoustic sensors based on piezoelectric thin films.

Effect of the Electrode Layer on the Deposition of AlN for Biosensors Academic Article in Scopus