Patent ID: 6165851
Filing Date: 2000-12-26
Classification: H01L

Abstract:
A method of fabricating a semiconductor nonvolatile storage comprising the steps of:forming a field oxide film on a semiconductor substrate,forming a first polycrystalline silicon film on the field oxide film,forming a mask oxide film on the first polycrystalline silicon film by oxidizing a surface of the first polycrystalline silicon film,forming an opening in the mask oxide film and forming on the first polycrystalline silicon film by oxidizing the surface of the first polycrystalline film within the opening a memory oxide film of thinner thickness than the mask oxide film,forming a second polycrystalline silicon film over the whole surface,forming a memory gate electrode by processing the second polycrystalline silicon film to a prescribed size extending over the memory oxide film and the mask oxide film thereabout by dry etching using hydrogen bromide as etching gas,removing bromide occurring as a reaction product of the hydrogen bromide by thereafter immersing the semiconductor substrate in a hydrofluoric acid aqueous solution, andforming a gate electrode by etching the first polycrystalline silicon film.