This review article presents recent advancements in the design and fabrication of thin‐film (<3 μm) lead zirconate titanate (PZT) microelectromechanical system (MEMS) devices. The article covers techniques for optimizing highly (001)/(100) oriented chemical solution deposited PZT films to achieve improved piezoelectric coefficients. These PZT films combined with surface and bulk micromachining techniques are fabricated into actuators and transducers for radio frequency (RF) switches, nanomechanical logic, resonators, and power transformers for use in communication systems and phased‐array radar. In addition, the large relative displacements generated by PZT thin films have been used to demonstrate mechanical mobility in MEMS devices, including insect‐inspired flight actuators and ultrasonic traveling wave motors. In conjunction with actuation, PZT films are being developed for feedback sensors for the integrated control of insect‐inspired robots.

This work attempts to optimize past research results on lead zirconate titanate (PZT) using the fabrication processes at the U.S. Army Research Laboratory so as to achieve a high degree of {001} texture and improved piezoelectric properties. A comparative study was performed between Ti/Pt and TiO 2 /Pt bottom electrodes. The results indicate that the use of a highly oriented {100} rutile phase TiO 2 led to highly textured {111} Pt which in turn improved both the PTO and PZT orientations. PZT (52/48) and (45/55) thin films with and without PTO seed layers were deposited and examined via x-ray diffraction (XRD) methods as a function of annealing temperature. The seed layer provides significant improvement in the {100} orientation generally, and in the {001} subset of planes specifically, while suppressing the {111} orientation of the PZT. Improvements in the Lotgering factor (f) were observed from an existing Ti/Pt/PZT process (f 5 0.66) to samples using the PTO seed layer deposited onto the improved Pt electrodes, TiO 2 /Pt/PTO/PZT (f 5 0.96).

The crystallographic texture of lead zirconate titanate (PZT) thin films strongly influences the piezoelectric properties used in MEMS applications. For PZT films poled to saturation, the piezoelectric response is sequentially greater for random, {111}, and {001} texture. Textured growth can be achieved by relying on crystal growth habit and can also be initiated by the use of a seed layer that provides a heteroepitaxial template. Template choice and the process used to form it determine the structural quality and ultimately influence performance and reliability of MEMS PZT devices such as switches, filters, and actuators. This study focuses on how {111}-textured PZT is generated by a combination of crystal habit and templating mechanisms that occur in the PZT/bottom-electrode stack. The sequence begins with {0001}-textured Ti deposited on thermally grown SiO2 on a Si wafer. The Ti is converted to {100}-textured TiO2 (rutile) through thermal oxidation. Then {111}-textured Pt can be grown to act as a template for {111}-textured PZT. The Ti and Pt are deposited by DC magnetron sputtering. The TiO2 and Pt film textures and structure were optimized by variation of sputtering deposition times, temperatures and power levels, and post-deposition anneal conditions. The relationship between Ti, TiO2, and Pt texture and their impact on PZT growth will be presented.

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