| 摘要 |
PURPOSE:To prevent the breakdown of a gate oxide film due to ion implantation and prevent the deterioration of gate breakdown voltage and the gate leaks by a method wherein a gate electrode is covered with a polycrystalline Si film and connected to the source and drain. CONSTITUTION:After field oxide films 2 are formed by selectively oxidizing a semiconductor substrate 1, a gate oxide film 3 is formed by oxidizing the substrate 1 again. Next, the gate electrode is formed by covering the gate part on the film 3 with the first polycrystalline Si film 4, and then the oxide films on the source 5 and drain 6 forming regions are removed with this gate electrode as the mask. Then, the entire surface on the substrate 1 is covered with the second polycrystalline Si film 8 thinner than the film 4, and an impurity is implanted by ion currents 7 via the film 8. The impurity is diffused into the source 5 and the drain 6 by heat treatment, and the film 8 is oxidized. |
