EPROM Cell with high gate injection efficiency

An n-channel erasable and programmable read-only memory (EPROM) with very high gate injection efficiency is described, which we call a perpendicularly accelerating channel injection MOS (PACMOS). PACMOS has a dual gate structure arranging a select-gate and a floating gate in series between the source and drain. The select-gate and the floating gate are biased as to conduct the source and the drain potentials into two channels under the respective gate. The channel injection utilizes a channel potential gap built in at the boundary of these two channels. A fabricated PACMOS has shown that it can be programmed by voltage of 8V and current of 0.15µA, where a total injection efficiency (gate current /drain current) amounts to 10^-3. It is considered that this very high gate injection efficiency is brought by the electron attractive field in the gate oxide under the floating gate.