| 摘要 |
PURPOSE:To obtain a dynamic memory cell which decreases a soft-error rate by the incidence of alpha rays by gradually sloping to the low concentration of impurities from the high concentration of impurities in the depth direction of a semiconductor substrate. CONSTITUTION:A substrate, concentration thereof is decreased gradually in the direction that the concentration of P type impurities inclines to the back side from the surface, is used as a P type semiconductor substrate 1. A field oxide film 2, an N type region 3, a gate oxide film 4 and polysilicon gates 6, 7 are formed. When the pairs of electronic holes are formed by the incidence of alpha rays, electrons formed in a depletion layer of the second region fall into the third region, and N type semiconductor region, by an electric field, electrons formed in the P type substrate of the first region move in the direction opposite to the depletion layer by the gradients of potential formed by concentration gradient of the P type impurities, and inflow to a stored potential-wall is prevented. |
