US 5,293,055 A · Semiconductor integrated circuit device

Abstract

In a CMOS-DRAM, an n-type silicon substrate has a p-type well formed therein, and a DRAM cell array is formed in the p-type well. In a period immediately after an external power supply is turned on, the p-type well is in a substantially floated condition. A predetermined time after the external power supply is turned on, the p-type well is applied with a predetermined DC voltage generated by a well voltage generating circuit. The CMOS-DRAM has a selective grounding circuit. When the external power supply is turned on, the selective grounding circuit forcibly grounds the plate electrode of the DRAM cell array for a predetermined period of time. Therefore, an increase in the well voltage at the cell array region, which increase may occur due to the capacitive coupling, is prevented when the power supply is turned on. Accordingly, adverse effects arising from the increase in the well voltage are prevented.

Claims19

Dependent claims

A DRAM comprising:

a semiconductor substrate;
a first region of a first conductivity type formed in the substrate;
a well of a second conductivity type, surrounded by the first region;
a capacitor formed in the well and having an plate electrode which is in capacitive coupling to the well;
a transfer MOS transistor serving as transfer gate means and formed in the well, said transfer MOS having a source/drain terminal connected to the capacitor;
a bit line connected to another source/drain terminal of the transfer MOS transistor;
a word line connected to a gate of the transfer MOS transistor;
means for applying a first potential to the first region;
means for applying a well potential to the well;
and
grounding means for temporarily grounding at least one of the plate electrode and the bit line when application of the first potential is started.

8 more elements

Dependencies are inferred from the claim text.

Semiconductor integrated circuit device

Life of this patent

Semiconductor integrated circuit device

Life of this patent

Abstract

Claims19