| 摘要 |
PURPOSE:To form a thick oxide film and a thin oxide film through a simple process by implanting nitrogen ions into a region, in which the oxide film having thin thickness is shaped, to form a nitride film and simultaneously oxidizing the region, into which nitrogen ions are implanted and a region into which the oxide film having thick thickness is shaped. CONSTITUTION:Field oxide films 4 and gate oxide films 10, 12 are formed to a silicon substrate 2, and a polysilicon layer pattern 14 for a floating gate electrode is shaped in a memory transistor region 6. Nitrogen ions are implanted while using a resist 16 as a mask. When the resist 16 is removed and the whole is oxidized, a nitride film 20 is formed on the interface between the silicon substrate 2 and the gate oxide film 12 through the implantation of nitrogen ions and heat treatment in an oxidation process in a preipheral transistor section 8, and the nitride film 20 prevents the oxidation of the silicon substrate 2. Accordingly, an inter-layer oxide film 18 in the memory transistor section 6 an be shaped in thick size togetherwise the gate oxide film 12 in the peripheral transistor section 8 in thin size. |
