RF sputtered PZT thin film at MPB for piezoelectric harvester devices

Abstract

Pb(ZrxTi1-x)O3 (PZT) thin films deposition at morphotropic phase boundary (MPB) and low temperature became one of the most promising fields in microelectromechanical systems (MEMS) for power harvesting applications, especially in a low frequency range, due to its large electromechanically coupling coefficient, dielectric and piezoelectric constants. PZT thin film deposition using RF sputtering has the advantage over other deposition methods due to its simplicity, better parameter control, cheapness, and requires a low deposition temperature. The influence of plasma parameter (RF power, Ar gas content and pressure) is studied to deposit the optimum Pb Zr 0.52 Ti 0.48 O3 thin film with 1μm thickness. The NTI nano film RF sputtering system was used to deposit the 36 samples of PZT thin film in (Si3N4/Si) substrate, the working temperature is at 20C°. The post annealing process with conventional treatment at 650 C° for 60 min is done. MERLIN compact FESEM is used to measure the cross section thickness of samples at four different points and an average is taken, thickness standard deviation and the radius of curvature is measured to check thin film uniformity and flatness. To determine the plasma parameters necessary for optimum thin film deposition, Energy dispersion spectroscopy (EDS) is used to analyze the chemical composition of deposited PZT thin film and found that 250 W of RF power, 15mT of Ar gas pressure, and 18 Sccm of Ar gas content is necessary for Pb Zr 0.52 Ti 0.48 O3 thin film deposition. A XRD technique is used to study phase formation in optimized PZT thin film. The perovskite phase (100, 110, and 111,200) is observed with maximum peak intensity of 1200 counts/ second for 110 phases. Piezoelectric constant d33 of 413 pm/v and 0.68 electromechanical coupling coefficient, which make the optimize PZT thin film (Pb Zr 0.52 Ti 0.48 O3) suitable in power harvesting devices at low frequency rang such as cardiac pacemaker.