Low thermal budget lead zirconate titanate thick films integrated on Si for piezo-MEMS applications

Piezoelectric cantilevers made from ferroelectric thick films are commonly used as key components in many prototypical piezo-MEMS devices, including sensors, micro-actuators and piezoelectric energy harvesters. In this work, transverse piezoelectric performance of rapid thermal annealed Pb(Zr0.53Ti0.47)O3 (PZT) thick film (~1-2 μm) were characterized. These films were sputtered on LaNiO3 buffered Pt/Ti/SiO2/(100) Si substrates at 350 °C followed by a rapid thermal process (RTP) with different annealing time (30 s to 15 min) at the high temperature end (700 °C), and then patterned into rectangular prism-shaped cantilevers. Such a two-step process yields highly (001)-oriented perovskite PZT films with good overall electrical properties (ferroelectric, dielectric and piezoelectric) close to those of an epitaxial PZT film, yet on a much reduced thermal budget. With the elementary and chemical valence information from EDS and XPS analysis, an optimal annealing time was determined for the PZT thick film cantilevers to have both an outstanding piezoelectric performance (actuating, sensing or energy harvesting), and a good compatibility with the Si technology (a brief exposure to a high temperature). This study promotes the integration of large piezoelectricity into Si-based MEMS.