A semiconductor device includes a first substrate, a transistor disposed on the first substrate, and a first interconnection layer connected to the transistor. The first interconnection layer includes a first conductive line, a second conductive line, and a third conductive line, which are spaced apart from each other in a first direction parallel to a top surface of the first substrate. The second conductive line is disposed between the first conductive line and the third conductive line. A top surface of the second conductive line is located at a height higher than top surfaces of the first and third conductive lines with respect to the top surface of the first substrate.