Fabrication and characterization of the electrets material for electrostatic energy harvester

Abstract

Electrostatic energy harvesting devices have been found feasible to convert ambient vibrations into electrical energy. Fabrications of such devices are carried out using standard CMOS technology. This paper explains the fabrications processes of the energy harvesting components and the characterizations of the electret material for the electrostatic energy harvester device. The electrostatic energy harvester components are made up of the trapezoidal electrodes and electrets structures. The aluminum-silicon-copper (AlSiCu) electrodes reside on the Micro Electro-Mechanical System (MEMS) structure of 25 mm2 and comprises the seismic mass and serpentine beams. On the other hand, the electrets which made up of Silicon Dioxide (SiO2) and Silicon Nitride (Si3N4) material, are fabricated separately. A 0.35 μm CMOS processes technology is utilized to fabricate the electrodes and electrets structures onto 200 mm silicon wafers. The performance of the energy harvester is evaluated through the characterizations of the electrets material. The electrets are charged with the Corona charging method and the surface potential is measured. From the experiment, it is proven that the CVD oxides is chargeable at 4.7 kV Corona voltage, 200 V grid voltage, 10 minutes charging time and 70°C substrate temperature, hence it is a recommended material for electrostatic energy harvester device.