A method of fabricating a semiconductor device includes providing a substrate including a pair of first regions and a second region therebetween, forming first patterns on the respective first regions to at least partially define a stepwise portion at the second region, and forming a dummy pattern that at least partially fills the stepwise portion. The dummy pattern may be an electrically floating structure. The dummy pattern may be formed as part of forming second patterns on the respective first regions, and the dummy pattern and the second patterns may include substantially common materials. Because the dummy pattern at least partially fills the stepwise portion at the second region, the material layer covering the second patterns and the dummy pattern may omit a corresponding stepwise portion.