Fabrication of a piezoelectric microcantilever array with a large initial deflection and an application to electrical energy harvesting

Abstract

This paper presents a new method to fabricate a multi-layered PZT microcantilever with a large upward initial deflection and the application for energy harvesting. The upward initial deflection is obtained by asymmetrically distributed residual stresses in the thin multilayer. The numerical analysis is carried out to simulate the upward deflection only based on the temperature history of process. In particular, the proposed method using the metal etching of the adhesion layer of tantalum and the plasma ashing of parylene-C is compared with that using the dry etching of polycrystalline silicon as a sacrificial layer to release the microcantilever from the substrate in fabrication simplicity and process time. An experimental evaluation confirmed that the proposed fabrication method is very simple and effective. The feasibility of the electricity generation is also measured on the PZT vibration test bed. A nano-watt electrical output is obtained, much higher than noise level. Also, a large output is obtained at a large length of the microcantilever with a large initial deflection.