| 摘要 |
PURPOSE:To improve the reliability of memory holding characteristics by forming an oxidized film for improving the pattern shape of a double gate made of the first and second polysilicon film and interlayer oxidized film after patterning of the double gate structure and before forming source and drain. CONSTITUTION:A sequential patterning is performed in the prescribed pattern shape, and a resist mask 6 is removed by an oxygen plasma. An oxidation is performed, thereby forming an oxidized film 11 on the second polysilicon film 5 and the end of the exposed first polysilicon film 3, and a recess 12 between the first and second films 3 and 5 is filled substantially with the film 11, thereby improving the pattern shape of the gate 13. A phosphorus film does not almost enter between the first and second films 3 and 5, and the withstand voltage of an interlayer insulating film 4 is raised from 65V of the conventional one to 85V, with the result that the reliability of charge holding characteristic can be largely improved. |
