Fabrication and analysis of high-performance piezoelectric MEMS generators

In this paper, we have designed a fabrication process for microgenerators by bonding a piezoelectric ceramic Pb(Zr, Ti)O-3 (PZT) plate to a silicon on insulator (SOI) wafer. The key techniques of the process include the low-temperature bonding technique using conductive epoxy resin, thinning of the bulk PZT using mechanical lapping and wet-etching combined method, and the micromachining of bulk ceramics by dicing. Through the development and optimization of the process, a piezoelectric MEMS power generator array was successfully fabricated. The typical device is selected to characterize the output performance of the microgenerators, while the composite beam dimension of PZT and silicon layer is about 3080 mu m x 800 mu m x 31 mu m and the dimension of Ni proof mass is about 900 mu m x 800 mu m x 450 mu m. The experimental results show that the output voltage, output power and power density of this device are 2.72 VP-P, 11.56 mu W and 28 856.7 mu W cm(-3) at the resonant frequency of 514.1 Hz when it matches an optimal resistive load of 70 k Omega under the excitation of 1g acceleration. The output performance of this device is higher, compared with that of other reported MEMS power generators, which demonstrates that this novel technique has great potential to fabricate high-performance piezoelectric MEMS energy harvester.