A semiconductor device includes a flip flop cell. The flip flop cell is formed on a semiconductor substrate, includes a flip flop circuit, and comprises a scan mux circuit, a master latch circuit, a slave latch circuit, a clock driver circuit, and an output circuit. Each of the scan mux circuit, the master latch circuit, the slave latch circuit, the clock driver circuit, and the output circuit includes a plurality of active devices which together output a resulting signal for that circuit based on inputs, is a sub-circuit of the flip flop circuit, and occupies a continuously-bounded area of the flip flop circuit from a plan view. At least a first sub-circuit and a second sub-circuit of the sub-circuits overlap from the plan view in a first overlap region, the first overlap region including part of a first continuously-bounded area for the first sub-circuit and part of a second continuously-bounded area for the second sub-circuit.