MEMS based thin film 2 GHz resonator for CMOS integration

This paper describes the development of the aluminum nitride (AlN) thin film bulk acoustic resonator (FBAR) using noble MEMS techniques for CMOS integration. This resonator has an air gap between a substrate for acoustic isolation. Germanium (Ge) was used as a sacrificial layer to make the air gap. This technique gives simple process and high CMOS compatibility. The resonator achieved a Q factor of 780 and an effective electro-mechanical coupling constant (k/sub eff//sup 2/) of 5.36 % at a resonant frequency of 2 GHz.