Nitride spacer technology for flash eprom

Abstract

A method of forming a spacer structure adjacent to the sidewall of a floating gate electrode with a top surface and sidewalls, the floating gate electrode being formed on a silicon oxide dielectric layer, and the silicon oxide dielectric layer being formed on the top surface of a semiconductor substrate include the following steps. Form a cap layer on the floating gate electrode, and a blanket tunnel oxide on the device. Form an inner dielectric, spacer layer over the device including the cap layer and the sidewalls thereby with conforming sidewalls, and an outer dielectric, spacer layer over the inner dielectric, spacer layer including the conforming sidewalls. Partially etch away the outer dielectric, spacer layer with a dry etch to form a outer dielectric spacer adjacent to the conforming sidewalls. Then partially etch away more of the outer dielectric, spacer layer with a wet etch to expose a portion of the conforming sidewalls of the inner dielectric, spacer layer. Finally, etch away the portion of the inner dielectric, spacer layer unprotected by the outer dielectric spacer before forming interelectrode dielectric layers and the control gate electrode.