In a stacked semiconductor device and method of manufacturing the same, an insulation multilayer pattern is formed on a substrate. The insulation multilayer pattern includes a first insulating interlayer pattern, a second insulating interlayer pattern and an opening exposing a surface of the substrate. A first channel pattern may be interposed between the first insulating interlayer pattern and the second insulating interlayer pattern, with a sidewall of the channel pattern being exposed through the opening. A barrier metal layer including a first continuous sub-layer is provided along a sidewall and bottom surface of the opening. The first sub-layer may have a substantially uniform thickness around the first channel pattern.