Integrated circuit including cells of different heights and method of designing the integrated circuit

An integrated circuit includes a first column including a plurality of first cells aligned and placed in a plurality of first rows, each first row having a first width and extending in a first horizontal direction, a second column including a plurality of second cells aligned and placed in a plurality of second rows, each second row having a second width and extending in the first horizontal direction, and an interface column extending in a second horizontal direction perpendicular to the first horizontal direction between the first column and the second column, wherein the interface column includes at least one well tap configured to provide a first supply voltage to a well, and at least one substrate tap configured to provide a second supply voltage to a substrate.