Surface micromachined piezoelectric resonant beam filters

Piezoelectric actuation and sensing of suspended single-beam microelectromechanical system (MEMS) resonant filters is demonstrated. Resonant frequencies between 171 kHz and 9.2 MHz were observed for resonators with dimensions of 6-20 mum wide and 25-400 mum long. Operation was demonstrated from a vacuum pressure of 20 mTorr to atmospheric with drive voltages as low as 2.5 mV and a dynamic range of greater than 40 dB. Loaded quality factors (Q(s)) greater than 1000 resulted at 9.2 MHz and a 20 mTorr pressure. A 20 kHz tuning range resulting from the piezoelectric poling conditions and a 75 ppm/K frequency temperature dependency was observed. The resonators utilize a clamped-clamped beam design with sol-gel lead zirconate titanate (PZT) as the piezoelectric actuator and sensor, PECVD silicon dioxide as the resonant beam structure, and platinum as the top and bottom electrode. The effects of operating temperature, operating pressure, poling condition, and drive voltage are reported. (C) 2001 Elsevier Science B.V. All rights reserved.