A method of fabricating an image system includes forming a first wafer that includes a first semiconductor substrate and a first interconnect layer. A pixel array is formed in an imaging region of the first semiconductor substrate and a first insulation-filled trench is formed in a peripheral circuit region of the first semiconductor substrate. Additionally, a second wafer is formed that includes a second semiconductor substrate and a second interconnect layer. A second insulation-filled trench is formed in a second semiconductor substrate, and the first wafer is bonded to the second wafer. A third interconnect layer of a third wafer is bonded to the second wafer. At least one deep via cavity is formed through the first and second interconnect layers and through the first and second insulation-filled trenches. The at least one deep via cavity is filled with a conductive material to form a deep via.