A method of fabricating a semiconductor device includes forming first cell patterns on a substrate, forming a first layer relative to the first cell patterns, and forming a second cell pattern and a peripheral pattern on the first layer. The second cell pattern includes first holes in a cell region and the peripheral pattern is located in a peripheral region. The method also includes filling the first holes, removing the second cell pattern to expose pillars, and forming second holes. Each of the second holes corresponds to adjacent cell spacers of the pillars. The method also includes removing the pillars to form third holes corresponding to respective ones of the cell spacers, and etching the substrate using the cell spacers, the first cell patterns, and the peripheral pattern as etch masks to form a trench.