Thin film piezoelectric property considerations for surface acoustic wave and thin film bulk acoustic resonators

We report on the optimisation of thin film piezoelectric ZnO for production of resonant acoustic MEMS devices (SAW and FBAR/BAW). The ZnO was deposited by RF sputtering, and conditions were optimised to promote uniform polycrystalline orientation, high resistivity and smooth surface morphology. Both surface acoustic wave and thin film bulk acoustic resonators exhibited high Q values with low insertion loss (3–5 dB).