| 摘要 |
PURPOSE:To improve the withstanding voltage between upper and lower poly Si films, by forming an oxide film on the surface of a nitride basis film, and forming a double-layer poly Si structure on said oxide film. CONSTITUTION:A field oxide film 12 and a gate oxide film 13 are formed on an Si substrate 11. A thin Si nitride film 14 is formed on the entire surface and an oxide film 15 is formed by oxidation. Then, a first poly Si film 16 is provided on the entire surface. Impurities are introduced and conductivity is imparted. Thereafter, the film 16 other than parts, which are to become the first gate electrode and wirings, is removed by photolithography technology. Then, with the remaining film 16 as a mask, the films 15, 14 and 13 are removed. Thereafter, the entire surface is oxidized by water vapor, and a second gate oxide film 17 and an interlayer insulating film 18 are formed. Then, a second poly Si film 19 is formed on the entire surface, and impurities are introduced. The film 19 is patterned, and the second gate electrode and the wirings are formed. With the film 19 as a mask, the film 17 is etched, impurities are introduced and a diffused layer 20 is formed. |
