| 摘要 |
PURPOSE:To obtain a solid-state image pickup device with little random noise by a method wherein a portion under a diffused layer contacting with a vertical signal line is constructed by a four-layer structure composed of n<+>-p<->-p<+>-p<-> well deposit layers. CONSTITUTION:A p<-> layer 12 is provided between an n<+> diffused layer 4 and a p<+> layer 6. Regarding this p<->12, it can be said that when an impurity, e.g. phosphorus, opposite to the one of the p<+> layer 6 is diffused into this layer, an n type impurity is put into a p type impurity layer and consequently the density of the p<+> layer 6 is reduced equivalently. Assuming that the impurity density of the p<+> layer 6 is Np<+>, the capacity Cv of a vertical signal line 11 is reduced by the reduction of the density of the p<+> layer 6, since Cvproportional (Np<+>)<1/2>. By this constitution, random noise can be lessened, and thus an image having a high S/N ratio and a very high quality can be obtained. |
