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 μm thick. The natural resonance frequencies of the beams were determined from impedance measurements. The resonance frequency was found to follow a L^-2 dependence, where L is the cantilever length. An effective elastic constant, s₁₁, for the beam structures of 15.7×10^-12m²N^-1 was thus calculated. The effect of bias fields on the effective electromechanical coupling factor, k₃₁, was also determined from the resonance data. Maximum k₃₁ values measured were approximately 0.15, or about half of those reported for PZT bulk ceramics