A dummy cell arrangement in a semiconductor device includes a substrate with a dummy region, unit dummy cells arranged in rows and columns in the dummy region, and flexible extended dummy cells arranged in rows and columns filling up remaining dummy region. The unit dummy cell includes exactly one base dummy cell and exactly two fixed dummy cells at opposite sides of the base dummy cell in row direction or in column direction and the flexible extended dummy cell includes at least two base dummy units and a plurality of flexible dummy units at two opposite sides of the two base dummy units in row direction or in column direction. The base dummy cell consists of at least one fin, at least one gate and at least one contact, while the flexible dummy cell consists of one gate and one contact without any fin.