Piezoelectric response of PZT thin film actuated micromachined silicon cantilever beams

Micromachined cantilever beams actuated by sol-gel derived lead zirconium titanate (PZT) thin films are reported. Rectangular cantilevers of sub-millimeter dimensions and several different aspect ratios were fabricated. The PZT films utilized for these structures were 0.44 /spl mu/m thick. The natural resonance frequencies of the beams were determined from impedance measurements. The resonance frequency was found to follow a L/sup -2/ dependence, where L is the cantilever length. An effective elastic constant, s/sub 11/, for the beam structures of 15.7/spl times/10/sup -12/m/sup 2/N/sup -1/ was thus calculated. The effect of bias fields on the effective electromechanical coupling factor, k/sub 31/, was also determined from the resonance data. Maximum k/sub 31/ values measured were approximately 0.15, or about half of those reported for PZT bulk ceramics.