SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

PURPOSE:To control a change of the substrate potential by providing a capacitance between the substrate terminal and the grounding terminal. CONSTITUTION:The MOS dynamic RAM2 and the MOS capacitance-group 3 for preventing a change of the substrate potential are formed on the silicon substrate. The RAM2 is composed of MOS FETs and MOS capacitances. In the MOS capacitance-group 3, three MOS capacitances 4 the thickness of each insulating film of which is approximately equal to that of the gate film of the RAM2 are arranged in parallel and the total capacitance is greater than any capacitance of each MOS FET or MOS capacitance of the RAM2. The grounding potential Vss is applied to the capacitance 4, the potential VBB on the order of -2 volts is given to the substrate by the substrate potential self-generator. Also the potential VDD of about 5 volts is applied to the drain of the FET of RAM2. In this way, even through the substrate current IBB is changed by a selective on-off operation of the FET, a change of the substrate potential VBB can sufficiently be absorbed since the total capacitance of the capacitance-group 3 is greater.