A semiconductor device includes a plurality of pillar structures on a semiconductor substrate, and a support pattern in contact with at least a part of each of the pillar structures, the support pattern connecting the pillar structures with one another, wherein the support pattern includes support holes exposing side surfaces of the pillar structures, the support holes including at least a first support hole and a second support hole that are spaced apart from each other, the first and second support holes having different shapes from each other.