| 摘要 |
PURPOSE:To prevent soft errors due to the irradiation of alpha rays by a method wherein the drain region used as a bit line is formd by using the silicon semiconductor layer on an oxide film so that the contact area between the drain region and the semiconductor substrate is made exceedingly small. CONSTITUTION:A thin oxide film formed on a semiconductor substrate 11 is selectively oxidized to form a thick oxide film 15 on the whole except for the portion where a memory capacitor is to be formed. Then, patterning is performed to leave the thick oxide film at the portion where a drain region is to be formed, and monocrystalline and polycrystaline Si layers 17P and 17S are grown. After said processes, n<+> type source regions 22S and 22ST, a drain region D and a drain region 22T to be a bit line are formed by the ion implantation. Accordingly, there is no portion cutting into the substrate 11. In addition, the contact area between the drain region and the substrate 11 becomes exceedingly small, so that the stretch of the depletion layer is made small. Thereby, the resistance to alpha rays is improved, and soft errors can be prevented. |
