| 摘要 |
PURPOSE: To inhibit a leakage current by a parasitic transistor without having an effect on the characteristics of a transfer gate by partially forming an impurity layer having an opposite conductivity type to a plate diffusion layer to the upper section of the plate diffusion layer. CONSTITUTION: A p<+> type inversion preventive layer 7 is formed onto the outer circumferential section of a trench 3 placed at the upper end of an n<+> type diffusion layer 8. Consequently, the inversion preventive layer 7 functions as a parasitic channel stopper between a source diffusion layer 151 and a plate diffusion layer 8. The n<+> type diffusion layer 7 is not formed just under a MOS transistor, thus reducing the possibility of the deterioration of a substrate bias effect, junction breakdown strength, etc. As a result, a parasitic channel leakage current can be inhibited without lowering transistor characteristics. Accordingly, A dynamic type semiconductor memory device having excellent data-holding characteristics can be realized even at the time of fining. |
