Microscanner actuated by double PZT thin film

Lead zirconate titanate (PZT) has been used in microsystems because of its high piezoelectric properties. We have succeeded in developing a beam and mirror scanner actuated by sol-gel deposited PZT (Pb(Zr,Ti)O-3) thin films as in our previous work. However, the problem of residual stress, which was observed in all fabricated devices, has not been solved yet. In this study, we developed a scanner actuated by double layered PZT to compensate for the residual stress and gain greater actuation force. The PZT layer was prepared by the sol-gel technique. The crystal orientation of the PZT films showed a strong (111) texture, which was reported to have good dielectric and ferroelectric properties in our previous work. The devices were fabricated through thin film depositions, lithography, dry plasma etching, and ICP releasing processes. By comparing with the conventional single layer PZT structure, the residual stress can be reduced in the double layered PZT structure. For a one dimensional bimorph beam scanner, an optical scanning angle of approximately 45-degree was obtained at a resonant frequency of 4.25 kHz, which is much larger than the one actuated by a single layered PZT unimorph beam scanner.