Epitaxial PZT films for MEMS printing applications

Abstract

Films of piezoelectric and ferroelectric oxides have been widely investigated for various applications, including microelectromechanical systems (MEMS) for printing. Pb(Zr,Ti)O3 is of particular interest due to its excellent piezoelectric properties. Control of the density, crystalline orientation, and compositional uniformity is essential to obtain these properties. In this article, we review recent progress on the fabrication of epitaxial Pb(Zr,Ti)O3films, in which the aforementioned control can be achieved. We discuss the different approaches used for the deposition of the epitaxial piezoelectric layer as well as the achieved degrees of the epitaxy. Furthermore, the integration of these piezoelectric layers in MEMS and the corresponding performance are discussed

Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses

“…We note that experimentally PZT films on Si substrates contain polydomain microstructures that form so as to relax thermal stresses due to the TEC mismatch and the transformational stresses due to the FE-PE phase transformation at T C . [59][60][61][62][63][64][65][66] Several studies have been reported which provide a rigorous analysis of polydomain heterostructures in epitaxial FEs taking into account these (volumetric) sources of internal stresses as well as localized strain fields near defects using thermodynamic models and phase-field approaches. 20,55,67,68 Therefore, to describe the experimental observations, more sophisticated models need to be developed to describe the effect of grain and domain boundaries, grain texture, and the extrinsic contribution to the pyroelectric coefficient resulting from reversible domain wall motion.…”

Ferroelectric and piezoelectric responses of (110) and (001)-oriented epitaxial Pb(Zr 0.52 Ti 0.48 )O 3 thin films on all-oxide layers buffered silicon

“…Schematic diagrams of the epitaxial relationship between PZT films, perovskite electrodes, YSZ-CeO 2 (fluorite) and silicon (diamond) structures were given in ref. [14]. Fig.…”

“…The width of the rocking curves is a measure of the range over which the lattice structure in the different grains tilts with respect to the film normal [14], and is therefore an indication of the homogeneity of the film Fig. 3.…”

“…Using appropriate conducting oxide buffer layers it is possible to fabricate all-oxide epitaxial layer devices, with much better or nearly perfect in-plane registry and significantly improved lifetime and properties [12,13]. Recently, epitaxial ferroelectric Pb(Zr,Ti)O 3 (PZT) thin films, especially with the composition Pb(Zr 0.52 Ti 0.48 )O 3 , have attracted considerable attention in device applications because of their often superior properties over polycrystalline thin films [14][15][16]. Several studies show that the growth of ferroelectric devices in the form of epitaxial thin films can be performed on both single-crystals (such as SrTiO 3 , LaAlO 3 and MgO) and Si substrates with different conducting perovskite layers as the bottom-electrode .…”

Characterization and reliability studies towards piezoelectrically actuated RF-MEMS switches

“…A prolonged exposure to high voltages is a prerequisite for the application of such devices in products. The reliability of the PZT thin films becomes a decisive factor in the commercialization of piezoelectrically actuated RF-MEMS switches [30,169,170].…”