Surface micromachined AlN thin film 2 GHz resonator for CMOS integration

This paper describes the development of the aluminum nitride (AIN) thin film bulk acoustic resonator (FBAR) using noble MEMS techniques for CMOS integration. An air-gap was fabricated under the resonator for acoustic isolation. Germanium (Ge) was used as a sacrificial layer to make the air-gap. This technique gives high CMOS compatibility. The resonator achieved a Q factor of 780 and an effective electro-mechanical coupling constant (k(eff)(2)) of 5.36% at a resonant frequency of 2 GHz. (C) 2004 Elsevier B.V. All rights reserved.