Piezoelectric and ferroelectrics films are very promising materials for micro-actuators in MEMS applications. In this paper, we present the fabrication and characterization of silicon membranes actuated by thin piezoelectric films. The influence of the membrane length implementation has been carefully analysed. Si/SiO2/PZT square membranes have been elaborated by DRIE etching using a SOI wafer, and a sputtering process for PZT thin films has been specifically developed. We have investigated the dynamic and static behaviour of these Si/SiO2/Ti/Pt/PZT/Pt membranes. We have a good correlation between electrical and mechanical measurements in dynamic characterisations. Sputtered PZT on 4 in. wafers leads to high quality material well suited for large membrane deflection up to several microns. Detailed processing information is given. (C) 2004 Elsevier B.V. All rights reserved.