A semiconductor device is provided. The semiconductor device includes first metal lines on a lower layer, a dielectric barrier layer provided on the lower layer to cover side and top surfaces of the first metal lines, an etch stop layer provided on the dielectric barrier layer to define gap regions between the first metal lines, an upper insulating layer on the etch stop layer, and a conductive via penetrating the upper insulating layer, the etch stop layer, and the dielectric barrier layer to contact a top surface of a first metal line. The etch stop layer includes first portions on the first metal lines and second portions between the first metal lines. The second portions of the etch stop layer are higher than the first portions.