Embodiments of methods and structures for forming a 3D integrated wiring structure are disclosed. The method can include forming an insulating layer on a front side of a first substrate; forming a semiconductor layer on a front side of the insulating layer; patterning the semiconductor layer to expose at least a portion of a surface of the insulating layer; forming a plurality of semiconductor structures over the front side of the first substrate, wherein the semiconductor structures include a plurality of conductive contacts and a first conductive layer; joining a second substrate with the semiconductor structures; performing a thinning process on a backside of the first substrate to expose the insulating layer and one end of the plurality of conductive contacts; and forming a conductive wiring layer on the exposed insulating layer.