In a method of forming a conductive pattern structure of a semiconductor device, a first insulating interlayer is formed on a substrate. A first wiring is formed to pass through the first insulating interlayer. An etch stop layer and a second insulating interlayer are sequentially formed on the first insulating interlayer. A second wiring is formed to pass through the second insulating interlayer and the etch stop layer. A dummy pattern is formed to pass through the second insulating layer and the etch stop layer at the same time as forming the second wiring. The second wiring is electrically connected to the first wiring. The dummy pattern is electrically isolated from the second wiring.