Semiconductor devices and methods of forming semiconductor devices are described. In one embodiment, at least one conductive structure is formed within a plurality of semiconductor substrates. At least portions of one of the conductive structures have oppositely facing, exposed outer surfaces. Individual substrates are stacked together in a die stack such that individual conductive structures on each substrate are in electrical contact with the conductive structures on a next adjacent substrate. In a preferred embodiment, the conductive structures comprise multi-layered, conductive pad structures.