A NEW MNOS CHARGE STORAGE EFFECT

This paper describes a new charge storage effect occurring in MNOS tetrodes. The physical phenomenon used for charge storage is direct carrier injection over the Schottky barrier between silicon and gate insulator rather than tunnelling. This mechanism avoids the problem of high electrical fields and slow operating speeds inherent in previous MNOS structures. The basic memory cell is an n-channel MOS stacked gate tetrode which has the additional advantage of a built-in three dimensional bit selection. A simple physical model for the injection effect and the experimental results which characterize it are presented. The application of this effect to an electrically alterable read-only memory is described in detail. © 1969.