| 摘要 |
PURPOSE:To prevent the rediffusion of impurities to the tunnel oxide film by a method wherein a semiconductor substrate has a tunnel oxide film made of an Si oxide film, which film has a floating gate made of polycrystalline Si doped with boron, a p type impurity. CONSTITUTION:An Si oxide film 2 is formed on the p type Si single crystal substrate 1, and a nitride film 3 is deposited and coated with a photo resist layer 4; further, the nitride film 3 is removed by etching by leaving the Si thermal oxide film 2. An n<+> layer 5 is formed by ion implantation with the mask of the photo resist layer 4 and then annealed; thereafter, the surface of the Si substrate 1 is exposed by removing the nitride film 3 and the Si oxide film 2, and an Si thermal oxide film 6 is formed by thermal oxidation. The Si oxide film 6 is coated with a photo resist layer, and the surface of the Si substrate 1 is exposed by etching away the Si thermal oxide film 6 with the mask of the photo resist. An Si thermal oxide film 7 is formed on the substrate surface, which surface is thermally nitrided into a thermal nitride film, and a polycrystalline Si 9 is deposited. |
