| 摘要 |
PURPOSE:To surely restrain production of soft errors by forming the dispersion layer of the same conductivity type as that of a substrate higher than impurity concentration of the substrate under the dispersion of a switching transistor. CONSTITUTION:After a field oxide film 2 and a gate oxide film 3 of a MOS type switching transistor are formed on a p-type silicon substrate 1, polysilicon is deposited and a gate electrode 4 and a word wire are formed. Next, with P ion-implanted, N dispersion layers 6a, 6b are formed. Thereafter an oxide film is deposited, anisortropic etching is performed and side walls 7a, 7b are formed. And with As ions implanted, N<+> dispersion layers 8a, 8b are formed. With B ions implanted, P-type layers 9a, 9b one figure higher than impurity concentration of the substrate 1 beneath the N<+> dispersion layer are formed. Therefore, at the time of operation of memory the extent of a depletion layer from the dispersion layer to the substrate side can be checked and the occurrence of soft errors can be restrained. |
