US Patent 10050028 Semiconductor device with reduced leakage current

An integrated circuit includes a substrate and a first set of functional cell units formed over the substrate. Each of the functional cell units includes a pair of functional cells that have different threshold voltages and a filler cell between the functional cells thereof. A number of the functional cell units in the first set is equal to or greater than a number of a second set of functional cell units, each of which includes a pair of functional cells that have different threshold voltages and that abut against each other. As such, a leakage current of the integrated circuit is reduced.