Mis-type semiconductor read only memory device and method of manufacturing the same

Claim 1

A metal-insulator-semiconductor type field effect transistor for memory use comprising a semiconductor substrate of one conductivity type, first and second regions of opposite conductivity type formed in said substrate, an alumina film formed on the surface of said substrate defined by said first and second regions extending to cover at least a portion of said surface between said first and second regions, a gate electrode formed on said alumina film, drain and source electrodes in ohmic contact respectively with said first and second regions, and a metal film formed in direct contact with said substrate, voltage means applied to said gate electrode for injecting negative charge carriers into said alumina film from one of said gate electrode and substrate, said voltage means above a critical value substantially permanently trapping said charge carriers in said alumina film; whereby said transistor is operable in two distinct states as a function of the gate voltage before and after the application of said voltage means.