Provided is an integrated circuit including a complementary field effect transistor including a first transistor and a second transistor arranged in a vertical direction on a front side of a substrate, a via structure extending in the vertical direction on the second transistor and interconnecting a source/drain of the second transistor to a source/drain of the first transistor, at least one frontside power rail disposed above the first transistor in the vertical direction and transmitting a first supply voltage to the first transistor, a backside via penetrating through the substrate in the vertical direction, and at least one backside power rail disposed on a back side of the substrate and transmitting a second supply voltage to the second transistor through the backside via, wherein the first supply voltage and the second supply voltage have different voltage levels, and the first transistor and the second transistor share a gate line.