An integrated circuit semiconductor device includes a lower electrode formed on a substrate extending in a first direction and a second direction perpendicular to the first direction and a support structure supporting the lower electrode. The support structure includes a support pattern surrounding the lower electrode, extending in the first direction and the second direction, and having a hole through which the lower electrode passes, and a concavo-convex structure having at a surface of the support pattern a plurality of convex portions extending in a third direction perpendicular to the first direction and the second direction, and a plurality of concave portions arranged between the convex portions.