| 摘要 |
PURPOSE:To prevent the diffusion of an impurity to a gate insulating layer by forming source-drain regions and doping the impurity to a gate electrode at the irreducible minimum of a demand. CONSTITUTION:An SiO2 layer 2 as a gate insulating layer, a poly Si layer 3 and a photo-resist 4 as an implantation stopping layer are applied onto a P-type Si substrate 1 in succession, and the photo-resist 4 and the poly Si layer 3 in a gate forming region are left through patterning. As<+> is implanted while using the photo-resist 4 as a mask, and N<+> type source-drain regions 5, 6 are formed through annealing. The photo-resist 4 is removed, As<+> is implanted to the whole surface of the substrate, and doped to the poly Si layer 3 in a gate electrode. The quantity of a dose at that time is made smaller than that for shaping the source-drain regions, but As<+> is doped to the poly Si layer 3 in the gate electrode at the irreducible minimum of a demand. Accordingly, an effect by a dopant on the gate insulating layer and the surface of the semi conductor substrate is eliminated, thus acquiring the thin insulating layer having normal device characteristics. |
