Characterization and application of jet-printed thin PZT layers for actuation of MEMS

Although piezoelectric thin films are of great interest for actuator application in MEMS, deposition of PZT films with thicknesses between 5 and 100 mu m has been hardly possible. It is therefore the goal of this paper, to investigate the properties of PZT-films of this thickness deposited by the recently introduced Jet-Printing System, especially concerning an application in micro actuator devices. First, PZT layers of thicknesses between 5 and 80 mu m have been Jet-Printed on different substrates to investigate the compatibility of the deposition method with standard materials used for MEMS (Micro-Electromechanical Systems). The relative dielectric constant of the layers could be determined between 20 and 550, depending on annealing and deposition conditions. Following, on thin (30 to 100 mu m thick) beam-shaped steel substrates PZT layers of 10 to 40 mu m thickness were deposited. Since the samples showed deformation caused by technology-introduced stress, the stress value is calculated by means of FEM calculation, and methods for avoiding and compensation of the deformation are introduced. Using the beam-shaped samples, for the first time the piezoelectric constant of the Jet-Printed PZT-layer was calculated to 20...30-10(-2) C/N from laser measurements of static and quasi-static beam deflection, and therefore piezoelectric actuation capability could be proofed directly.