A semiconductor device includes; a semiconductor substrate including a first region and a second region, a first interlayer insulating layer on the second region, a capping layer disposed on the first interlayer insulating layer, an upper surface of the capping layer includes a first trench, conductive patterns spaced apart on the capping layer, side surfaces of the conductive patterns are aligned with inner side surfaces of the first trench, and a peripheral separation pattern disposed in the first trench to cover the side surfaces of the conductive patterns. The peripheral separation pattern has a first thickness on the side surfaces of the conductive patterns and a second thickness greater than or equal to the first thickness on a lower surface.