A semiconductor device and a method of manufacturing a semiconductor device, the semiconductor device including a substrate; a first insulating interlayer on the substrate; a first wiring in the first insulating interlayer on the substrate; an insulation pattern on a portion of the first insulating interlayer adjacent to the first wiring, the insulation pattern having a vertical sidewall and including a low dielectric material; an etch stop structure on the first wiring and the insulation pattern; a second insulating interlayer on the etch stop structure; and a via extending through the second insulating interlayer and the etch stop structure to contact an upper surface of the first wiring.