Abstract: A method of producing a semiconductor device of the type which includes a semiconductor substrate; a gate insulating layer of a triplex structure formed on the semiconductor substrate and composed of a first oxide layer, an oxidation-resistant layer and a second oxide layer, and a gate electrode formed on the gate insulating layer, includes the steps of: forming the first oxide layer, the oxidation-resistant layer, and the second oxide layer successively on the semiconductor substrate; adjusting the thickness of the oxidation-resistant layer during or after the formation thereof in such a way that the entire oxidation-resistant layer can be oxidized in a post-process in which the oxidation-resistant layer is oxidized except for that region which corresponds to the gate electrode; and oxidizing the oxidation-resistant layer except for the region corresponding to the gate electrode and forming an oxide layer around the gate electrode, whereby the oxidation-resistant layer is entirely oxidized except for the reg

Abstract: In an MONOS type nonvolatile semiconductor memory comprising a channel forming semiconductor region between source and drain regions in a surface of a substrate; a tunnel insulating film formed on the channel forming semiconductor region in the surface of the substrate, the tunnel insulating film permitting charge-injection; a silicon nitride film formed as a second insulating film on the tunnel insulating film; a silicon oxide film formed as a third insulating film; and a conductive electrode formed on the silicon oxide film, the silicon nitride film has a composition close to a stoichiometric value of Si.sub.3 N.sub.4 at a portion near an interface with the tunnel insulating film and has a composition of excess silicon at a portion of the thickness of the same film except near the interface with the tunnel insulating film.

Abstract: A writable non-volatile memory circuit for use in portable electronic devices such as electronic timepiece, wherein there is improved the power consumption and there is provided a volatile memory with a serial input for writing the data into the non-volatile memory and for checking the data.