An integrated circuit structure includes a semiconductor substrate; a first active region in the semiconductor substrate; and a second active region in the semiconductor substrate and of an opposite conductivity type than the first active region. A gate electrode strip is over the first and the second active regions and forms a first MOS device and a second MOS device with the first active region and the second active region, respectively. A first spacer bar is in the semiconductor substrate and connected to the first active region. At least a portion of the first spacer bar is adjacent to and spaced apart from a portion of the first active region. A second spacer bar is in the semiconductor substrate and connected to the second active region. At least a portion of the second spacer bar is adjacent to and spaced apart from a portion of the second active region.