Semiconductor integrated circuit device

Abstract

A memory cell of the type employing a pair of cross-coupled CMOS inverters of a SRAM is disclosed in which the load MISFETs are stacked above the semiconductor substrate and over the drive MISFETs. Each load MISFET of a memory cell consists of a source, drain and channel region formed of a semiconductor strip, such as a polycrystalline silicon film strip, and a gate electrode consisting of a different layer conductive film than that of the drive MISFETs. In a memory cell having such a stacked arrangement, the source region and gate electrode of each load MISFET thereof are patterned to have a widely overlapping relationship with each other to form a capacitor element thereacross such that an increase in the overall capacitance associated with each of the memory cell storage nodes is effected thereby decreasing occurrence of soft error. The overlapping relationship for effecting the large capacitor element across the source and gate of the respective load MISFETs is provided by an ion implanting scheme of a p-type impurity into the semiconductor strip. A separate mask for ion-implantation for the formation of the source region of the load MISFET is added followed by the addition of the gate electrode thereof in a manner so as to have a widely overlapping relationship with that of the source region.