Abstract: An integrated circuit (IC) device includes a substrate, a pair of fin-type active regions protruding from the substrate to define a trench region on the substrate, the fin-type active regions extending in a first lateral direction, a pair of source/drain regions on the fin-type active regions, respectively, a device isolation film in the trench region, the device isolation film apart from the substrate in a vertical direction, an etch stop structure filling at least a portion of the trench region between the substrate and the device isolation film, a via power rail between the pair of fin-type active regions and between the pair of source/drain regions, the via power rail passing through at least a portion of the etch stop structure, and a backside power rail passing through the substrate, the backside power rail in contact with one end of the via power rail.