| 摘要 |
PURPOSE:To prevent the punch-through of P type impurity through a gate oxide film by controlling the concentration of each of the impurities while P type and N type impurities are mixed in gate poly Si. CONSTITUTION:A gate poly Si electrode 4 is already doped with phosphorus. In this state, the source-drain of P-channel are formed by boron ion implantation. In this case, if the phosphorus concentration is higher than the boron concentration by a figure, even in the mixed presence of boron in the electrode 4, the same threshold value as in the case of no boron content is obtained, leading to the state of no punch-through of boron through the gate oxide film 3. This manner unnecessitates the process of forming a mask layer for ion implantation to prevent the doping of the impurity for source-drain formation in the electrode 4, and accordingly the process is simplified. |
