Method of forming an ultra thin dielectric film for a capacitor

Abstract

The present invention provides a method of forming a ultra thin silicon nitride/silicon oxide (NO) dielectric layer over a polysilicon capacitor electrode formed adjacent to a silicon oxide insulating layer. First, a HF in-situ vapor clean is used to clean the polysilicon electrode and oxide insulating layers. A first silicon nitride (SiN) layer is then selectively deposited over the electrode. Next, the substrate is exposed to air. This grows a native oxide layer over the first silicon nitride layer and the insulating layer. Next, a second SiN layer is formed over the first silicon nitride layer, the insulating layer and the interface between the polysilicon electrode and the insulating layer. A thin oxide dielectric layer is grown over the second silicon nitride layer to complete the (NO) capacitor dielectric layer. The method of the present invention is an inexpensive process that provides an oxide free interface between the polysilicon and oxide layers. The method produces an uniform ultra thin silicon nitride/silicon oxide dielectric layer over a polysilicon electrode.

Dependencies are inferred from the claim text.