A semiconductor device includes a first transistor disposed over a substrate, a second disposed over the first transistor, and a conductive trace. The first transistor includes a first active area extending on a first layer. The second transistor includes a second active area extending on a second layer above the first layer. The conductive trace extends on a third layer. The first to third layers are separated from each other in a first direction, and the third layer is interposed between the first and second layers. The first active area, the second active area, and the conductive trace overlap in a layout view.