An integrated circuit includes first and second active regions, first and second standard cells on the first active region and the second active region, and a filler cell between the first and second standard cells and including first and second insulating isolations. The filler cell has a one-pitch dimension. The first and second insulating isolations are spaced the one-pitch dimension apart from each other. The first insulating isolation of the filler cell is disposed at a first boundary between the first standard cell and the filler cell. The second insulating isolation of the filler cell is disposed at a second boundary between the second standard cell and the filler cell. The first and second insulating isolations separate at least a part of the first active region, and at least a part of the second active region.