fabrication of a mosfet comprises , forming a dielectric layer on a substrate and a sacrificial structure on portions of the dielectric layer , forming a first polysilicon layer over the sacrificial structure and other exposed surfaces of the device , patterning the first polysilicon layer and the dielectric layer by masking and etching to form a stepped electrode structure partially upon the sacrificial structure and partially upon the other exposed surfaces of the device , applying ion implantation into the substrate outside of the area covered by the stepped electrode structure , removing the sacrificial layer from the surface of the substrate and from beneath the stepped electrode structure leaving an overhanging surface of the stepped electrode structure , forming a second layer of dielectric material on the exposed surfaces of the stepped electrode structure and the substrate , and forming a second polysilicon layer over and under overhanging portions the second layer of dielectric material and the substrate .