A switched-capacitor DC-to-DC converter includes a logic cell and a capacitor cell vertically overlapping with the logic cell. The logic cell has a plurality of active elements disposed over a first substrate. The capacitor cell has a capacitor over a second substrate. A first interlayer insulation layer disposed over the first substrate is bonded to a second interlayer insulation layer disposed over the second substrate. A first through via connected to any one of interconnection patterns of the logic cell and a second through via connected to a lower electrode pattern of the capacitor cell are connected to each other through a first external circuit pattern. A third through via connected to an upper electrode pattern of the capacitor cell and a fourth through via connected to another one of the interconnection patterns of the logic cell are connected to each other through a second external circuit pattern.