| 摘要 |
PURPOSE:To accelerate a mask memory and to reduce a chip area by simultaneously precharging the source and drain regions of longitudinally stacked mask ROM MOSFETs from a substrate. CONSTITUTION:A well 8 is epitaxially grown on a substrate 7 to form an electrically independent well. MOSFET T1-Tn, voltage applying electrode 9 are formed on the well 8. The well 8 and the source of the MOSFET Tn are connected to the output of an inverter 10 which inputs a clock pulse. When the clock pulse becomes ''0'', the well 8 and the source and drain electrodes of the MOSFET T1-Tn are simultaneously precharged with the P-N junctions formed of the source and drain electrodes of the MOSFET T1-Tn as forward bias. Accordingly, the precharging period is reduced to raise the operating speed, and the exclusive precharging element can be eliminated to reduce the chip area. |
