Patent ID: 6417052
Filing Date: 2002-07-09
Classification: H01L

Abstract:
A fabrication process for a semiconductor device comprising the steps of:forming a field insulating layer for device isolation selectively at a surface of a semiconductor substrate made of silicon to form a first and a second semiconductor regions separated from each other by the field insulating layer; oxidizing the surfaces of the first and second semiconductor regions to form a first and a second silicon oxide films, respectively; forming a first and a second silicon nitride films respectively on the first and second silicon oxide films by a chemical vapor deposition method using a compound gas including silicon and hydrogen, but substantially without chlorine, and ammonia as a source gas; applying a photoresist film selectively on the first silicon nitride film; removing the second silicon nitride film not covered by the photoresist film and the second silicon oxide film therebeneath to expose a surface of the second semiconductor region; removing the photoresist film remaining on the first silicon nitride film after the exposure of the second semiconductor region; again oxidizing the exposed surface of the second semiconductor region to form a third silicon oxide film with a thickness different from that of the first silicon oxide film at the surface of the second semiconductor region; and forming a first and a second gate electrodes on the first silicon nitride film and the third silicon oxide film, respectively, to fabricate a first and a second insulated gate devices having gate insulating films with different thickness at the first and second semiconductor regions, respectively.