Patent ID: 7060558

Claim:
A method for fabricating a field-effect transistor having a floating gate, which comprises the steps of: providing a semiconductor substrate having a surface; forming a layer construction on a part of the surface of the semiconductor substrate, the layer construction containing, as a bottommost layer, a tunnel dielectric for the floating gate, above that an intermediate layer made of a material of the floating gate and, as a topmost layer, a coupling dielectric having a nitride layer; implanting, after an application of the nitride layer of the coupling dielectric, nitrogen into the material of the floating gate in a quantity for appreciably reducing oxidation at sidewalls of layer construction, the nitrogen being implanted through the nitride layer into the material of the floating gate; patterning the layer construction to form the sidewalls defining part of a contour of the floating gate and resulting in a patterned layer construction; subsequently, coating a remaining part of the substrate surface and the sidewalls of the layer construction with an oxide layer through an action of an oxidizing atmosphere; subsequently, applying a further material for forming a control gate; patterning a geometry of an overall layer construction formed of the patterned layer construction and the further material for forming the control gate to a desired contour resulting in a patterned overall layer construction; and performing a post-oxidation of all surfaces including the sidewalls of the patterned layer construction resulting in a post oxide.