A method for manipulating a circuit design includes receiving multiple dummy cell modification parameters, selecting, by a computer processor and based on the dummy cell modification parameters, a dummy cell insertion region on a circuit design, and generating, in the dummy cell insertion region, multiple dummy cells. The method further includes selecting a first dummy cell from the dummy cells, determining, by the computer processor and based on a location of the first dummy cell, an illegal overlap with the first dummy cell, and removing, by the computer processor and from the dummy cells, the first dummy cell. The method further includes inserting, by the computer processor, on the circuit design, and after removing the first dummy cell, the dummy cells to obtain a modified circuit design, and presenting the modified circuit design.