A semiconductor device includes; a substrate including a first region and a second region, a first active pattern extending upward from the first region, a first superlattice pattern on the first active pattern, a first active fin centrally disposed on the first active pattern, a first gate electrode disposed on the first active fin, and first source/drain patterns disposed on opposing sides of the first active fin and on the first active pattern. The first superlattice pattern includes at least one first semiconductor layer and at least one first blocker-containing layer, and the first blocker-containing layer includes at least one of oxygen, carbon, fluorine and nitrogen.