| 摘要 |
PURPOSE:To restrict formation of natural oxide film on a polycrystalline silicon layer and to enhance storage capacity of charge by forming an insulating film on the polycrystalline silicon layer and then implanting impurities into the polycrystalline layer through the insulating film. CONSTITUTION:The surface of a semiconductor substrate 1 is oxidized between field insulating films 2 to form a gate insulating film 4, an undoped polycrystalline silicon is then formed entirely on the semiconductor substrate 1 and subjected to phosphorus treatment. A silicon oxide film is then formed entirely on the polycrystalline silicon and subjected to selective etching thus forming a gate electrode. An n-type impurity section of phosphorus, for example, is then formed through ion implantation on the surface of the semiconductor substrate 1 which is then annealed to provide n<->-type source and drain regions. A silicon oxide film is then formed entirely on the semiconductor substrate 1 to form a side wall 7. An undoped polycrystalline silicon layer is then formed entirely on the surface of the semiconductor substrate 1 followed by formation of an insulating film such as a silicon oxide film. |
