An IC device includes a polycrystalline silicon thin film interposed between a first level semiconductor circuit and a second level semiconductor circuit which are formed on a substrate and disposed to vertically overlap each other. The polycrystalline silicon thin film includes at least one silicon single crystal. The at least one silicon single crystal includes a flat horizontal portion, which provides an active region of the second level semiconductor device, and a pin-shaped protruding portion protruding from the flat horizontal portion toward the first level semiconductor device.