Formation of a SiO2/Si3N4/SiO2 electret on a silicon substrate

A new technique is presented for creating a thermoelectret from a PECVD multilayer film of SiO₂/Si₃N₄/SiO₂ using a direct contact cathode. The materials used have the advantage of being compatible with standard microfabrication processes. The electret film and activation process can be completed with equipment that is already available in many facilities. Effective surface voltages (ESV) of -236.2 V are possible and the lifetime coefficient for decay shows that it should operate for decades in standard packaged environments below 125°C.