Abstract: Fully integrated non-volatile and fixed threshold field effect devices are fabricated in N-channel technology on a single semiconductor substrate. MOSFET devices of the metal-nitride-oxide-semiconductor (MNOS) devices are used both as fixed threshold support devices and as variable threshold non-volatile memory array devices. Extremely stable and reproducible device characteristics result from the use of low charge containing dielectrics which allow optimum variable threshold stability and allow the use of operating potentials compatable with conventional fixed threshold FET devices. Low temperature processing following deposition of variable threshold gate dielectric enables all enhancement mode operation. A field oxide structure including a thin silicon dioxide layer, an aluminum oxide layer and a nitride layer provides parasitic threshold voltages in excess of 60 volts and prevents sub-threshold leakage.