A
semiconductor device includes: first and second
cell regions including corresponding active regions (ARs) in which are formed components of transistors. The first
cell region includes first and second ARs having a first height The second
cell region includes third and fourth ARs having a second height taller than the first height, and a fifth AR having a third height taller than the second height. The transistors of the first and second cell regions are arranged to function as a D flip-flop (DFF) including a primary latch and a secondary latch. The primary latch includes a first sleepy
inverter and a first non-sleepy (NS)
inverter. The secondary latch includes a second sleepy
inverter and a second NS inverter. Transistors which comprise the first and second NS inverters are in the first
cell region. Transistors which comprise the first and second sleepy inverters are in the second
cell region.