MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To decrease interfacial level by introducing a trace quantity of halogen to the interface between a wet oxide film or high pressure oxide film and substrate Si. CONSTITUTION:A semiconductor device, containing a trace quantity of halogen atoms at the interface between Si substrate and SiO2 formed by dry oxidation process, is oxidized in an oxygen atmosphere containing steam, or in a pyrogenic atmosphere, or in high pressure oxygen. By introducing a suitable quantity of halogen element such as F, Cl, having large bonding strength with Si, to the Si/SiO2 interface, the distortion at the interface can be relaxed. Thus, the surface leak, caused by the interfacial level produced at the interface between silicon oxide and Si and a fixed charge, can be prevented so that a highly reliable MOS device (for example, against the irradiation and hot carrier injection by X-ray, electron beam, etc.) can be formed.