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Abstract

A method for inhibiting generation of a native oxide film on the surface of a dielectric film in the process of fabricating a capacitor for a dynamic RAM is disclosed. A pure polysilicon layer inherently not liable to produce a native oxide film is formed as a lower electrode layer, and a thin thermal nitride film is formed b rapid thermal nitridation on the surface of the pure polysilicon layer. Impurities are then introduced via this thermal nitride layer into the lower electrode layer by ion implantation for rendering the lower electrode layer electrically conductive. Alternatively, an impurity-containing polysilicon layer having a native oxide film on its surface is processed by rapid thermal nitridation for causing a thermal nitride film to be grown at an interface between the native oxide film and the polysilicon layer, after which the surface native oxide film is removed. With both of these method variants, a thicker silicon nitride film is subsequently deposited on the thermal nitride film by a low-pressure CVD method for achieving a predetermined capacitor. Since the film quality of the dielectric film is markedly improved, long-term operational reliability of the dynamic RAM may be improved to diminish the leakage current.

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First Claim