Semiconductor memory device having a high capacitance storage capacitor

A semiconductor memory device for an integrated circuit comprising:

• a semiconductor substrate of a first conductivity type;
• a field insulation layer on the semiconductor substrate;
• a switch including a gate insulation layer, a gate electrode on the gate insulation layer, and a pair of impurity regions of a second conductivity type in the substrate adjacent to the gate electrode;
• a capacitor including a first electrode connected to one impurity region, a second electrode connected to a predetermined voltage, first insulation means for separating the first and second electrodes, and groove means extending into the substrate to a predetermined depth for increasing the capacitance area of the first electrode;
• and
• second insulation means at least partially overlapping one of the impurity regions adjacent said groove means;
• wherein the groove means includes a groove intersecting said one of the impurity regions and said second insulation means and extending into the semiconductor substrate, each of the first and second electrodes and the first insulation means being in part in the groove and in part extending outside the groove and overlapping a part of said second insulation means thereby to increase the capacitance of said capacitor.