A method of modifying a cell includes identifying a maximum overlapped pin group. The method further includes determining a number of pins in the maximum overlapped pin group. The method further includes determining a span region of the maximum overlapped pin group. The method further includes comparing the number of pins and the span region to determine a global tolerance of the cell. The method further includes increasing a length of at least one pin of the maximum overlapped pin group in response to the global tolerance failing to satisfy a predetermined threshold. The method further includes fabricating a mask based on the increased length of the at least one pin.