Semiconductor devices having through-vias and methods for fabricating the same are described. The method may include forming a hole opened toward a top surface of a substrate and partially penetrating the substrate, forming a sacrificial layer partially filling the hole, forming a through-via in the hole partially filled with the sacrificial layer, forming a via-insulating layer between the through-via and the substrate, and exposing the through-via through a bottom surface of the substrate. Forming the sacrificial layer may include forming an insulating flowable layer on the substrate, and constricting the insulating flowable layer to form a solidified flowable layer.