Tailoring of the Elastic Properties by Texture Control in Ferroelectric Thin Films for MEMS

Abstract

The use of piezoelectric thin films in advanced devices such as microelectromechanical systems (MEMS), not only rests on high piezoelectric coefficients, as the ones achieved in some ferroelectric lead titanate derived compositions, but also on their mechanical properties. This makes the study of the correlation between texture and elastic properties of high interest for the processing of piezoelectric thin films with tailored properties, regardless of which, not much related work has been reported up to now. In this paper we present the analysis of the variations observed in the elastic tensor of a series of modified lead titanate thin films with different orientations. The different textures were induced either by deposition on modified substrates or by changes of the annealing scheme. Orientation distribution functions (ODF) for all films were obtained by an advanced texture quantitative analysis of x-ray diffraction data of several pole figures. From the ODF and the single crystal tensor, we are able to calculate the effective elastic properties of the films by a geometric averaging procedure. This is a promising result in the tailoring of the mechanical properties of these piezoelectric thin films for applications.