5. Fabrication of Guided Beam Piezoelectric Energy Harvester

This chapter reports fabrication of guided two-beam and four-beam P-VEH in MEMS technology. A five-level mask process has been designed for device fabrication. TMAH CMOS compatible 25 wt.% wet etching has been used for the realization of pyramidal-shape seismic mass and DRIE for releasing the two-beam and four-beam structures. Corner compensation is used to obtain perfect edges at the bottom vertex for pyramidal-shaped seismic mass. A 2.5-μm-thick ZnO layer is sandwiched between the bottom and top electrodes for the generation and collection of electric potential. Beam thinning using DRIE is done from the backside of the silicon wafer to reduce the beam thickness resulting in a significant reduction in the resonance frequency of the devices. A special kind of PCB was designed having gold-plated pads suitable for wire bonding, and also, a special kind of PCB attachment was designed with a built-in connector and attached to the PCB so that the coaxial cable can be connected to the analyzer.