Dynamic semiconductor memory device on soi substrate

Abstract

In a dynamic semiconductor memory device including a thin film SOI/MOSFET having a semiconductor layer on an insulator as an active region, an 'L' level potential of a memory cell transistor, which connects/disconnects a capacitor for storing data as electric charges and a bit line for reading/writing data, is set at a fixed value higher than a ground potential and lower than a power supply potential, and a substrate bias is set at the ground potential. Even if isolation is carried out by LOCOS, sub-threshold leakage current due to a parasitic MOS in the vicinity of LOCOS edge can be suppressed because the potential of a word line is lower than that of the bit line when the memory cell transistor is in a cut-off state. Therefore, a dynamic semiconductor memory device including a thin film SOI/MOSFET which is immune to disturbing refresh can be achieved.