| 摘要 |
PROBLEM TO BE SOLVED: To eliminate remained polysilicon to prevent the occurrence of a short circuit, by making the film thickness of the gate insulating film of a first MIS transistor thicker at the center of the gate electrode than at the periphery of the gate electrode. SOLUTION: An oxidation process is provided after the gate electrode pattern of a memory cell is formed to oxidize a semiconductor substrate and remaining polysilicon 34a to form a silicon oxide film 34b, which eliminates the remaining polysilicon and hence a short circuit made by the remaining polysilicon. Since polysilicon around gate electrode itself of a semiconductor substrate and a memory cell is oxidized, the gate electrode has a structure in which an insulating film is thick at the center portion and thin at the periphery, which is different also in structure from a conventional semiconductor device. Therefore, this tends to improve resistance to hot carrier because of the effects of the oxidation of the semiconductor substrate and the shape of the gate insulating film and hence can provide a MIS transistor with high reliability. |
