Abstract: Provided is a method of fabricating a semiconductor device having a contact hole with a high aspect-ratio. The method includes: sequentially forming a lower pattern and an upper layer on a semiconductor substrate; sequentially forming a lower mask layer and an upper mask layer on the upper layer; sequentially patterning the lower and upper mask layers to form a hole exposing a top surface of the upper layer on the lower pattern; using the upper mask layer as an etching mask to anisotropically etch the exposed top surface to form an upper contact hole exposing a top surface of the lower pattern; and using the lower mask layer as an etching mask to anisotropically etch the exposed lower pattern to form a lower contact hole in the lower pattern, the lower contact hole extending from the upper contact hole.