Characterizations of Pb(Zr_0.52Ti_0.48)O₃ thin film processed for sensor and actuator applications

This paper describes the process and characterization of lead zirconate titanate (PZT) for sensors and actuators applications. The influence of substrate texture and properties along with the heat treatment process on the film crystallization mechanism is discussed. During the process, the Platinum bottom electrode is deposited on silicon substrate by electron beam evaporation (e-beam) process, providing us with a high quality Platinum layer to control PZT thin film growth. The surface quality of Titanium/Platinum (Ti/Pt) layer is analyzed using atomic force microscope (AFM). An optimized heat treatment process is proposed to obtain dense, uniform and cracks free PZT thin films with a fully perovskite crystallographic structure. Depending on Ti/Pt heat treatment, preferential PZT orientations (100) and (111) are successfully obtained. The films morphology is analyzed using Scanning Electron Microscope (SEM) and the crystallographic structure is studied using x-ray diffraction (XRD) and Raman spectroscopy. MIM (metal-insulator-metal) structures with different dimensions are fabricated to evaluate electric characteristics and ferroelectric effect of the proposed PZT thin films. A variation of capacitance value is successfully observed according to the variation of frequency, DC bias voltage and MIM structure dimensions. The relative permittivity is then extracted depending on capacitances variations. We demonstrate therefore that the capacitance and the relative permittivity presents a higher value for (111) than (100) oriented PZT thin film. This comforts the fact that (111) orientation is better for ferroelectric applications. (paper)