| 摘要 |
A memory cell of a dynamic storage device is composed of a MOSFET and a capacitor. On a single semiconductor substrate, a plurality of such memory cells are regularly arranged in a plurality of columns and constitute a memory cell array or memory cell mat. The capacitor for the memory cell is made up of a semiconductor region of the type which possesses a conductivity opposite to that of the semiconductor substrate, and a conductor film which is formed on the semiconductor region through a comparatively thin oxide film. On that surface of the semiconductor substrate which is not formed with the MOSFET's and the capacitors, a comparatively thick oxide film is formed. In that surface of the semiconductor substrate which extends along the vicinity of an end portion of the memory cell mat, there is arranged a semiconductor region of the type which possesses a conductivity opposite to, or the same as, that of the semiconductor substrate and which serves to prevent minority carriers created in the semiconductor substrate from flowing into the substantially opposite conductivity type semiconductor regions of the capacitors of the memory cells. The distance between this semiconductor region and the capacitor at the end part of the memory cell mat is made approximately equal to, or shorter than, the distance between the capacitors in the memory cell mat. Owing to this semiconductor region, the information holding time of the memory cells at the end portion of the memory cell mat becomes sufficiently long.
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