Research and Development of Miniaturized Electrets

This paper describes the realization process of small-size elec-trets by using techniques generally applied in the fabrication of integrated circuits and microsensors. In the first part of the paper, attention is paid to the different electret decay mecha-nisms and their relative contribution to the overall stability of miniaturized electrets. Then, a process is described by which polymer electrets such as Teflon-FEP and PTFE can be de-posited and shaped in a predefined pattern on a silicon wafer. In the third part, results on the application of new materials, especially silicon dioxide ( S i o s) , for use in electret applications, are presented. It appears that after an appropriate treatment of the oxide surface, its charge-stability is at least equal to that of polymer electrets such as Teflon-FEP and PTFE. 1