An integrated circuit includes a first and a second standard cell. The first standard cell includes a first gate electrode, and a first channel region underlying the first gate electrode. The first channel region has a first channel doping concentration. The second standard cell includes a second gate electrode, and a second channel region underlying the second gate electrode. The second channel region has a second channel doping concentration. A dummy gate includes a first half and a second half in the first and the second standard cells, respectively. The first half and the second half are at the edges of the first and the second standard cells, respectively, and are abutted to each other. A dummy channel is overlapped by the dummy gate. The dummy channel has a third channel doping concentration substantially equal to a sum of the first channel doping concentration and the second channel doping concentration.