A technology capable of simplifying a process and securing a misalignment margin when bonding two wafers to manufacture an image sensor using backside illumination photodiodes. When manufacturing an image sensor through a 3D CIS (CMOS image sensor) manufacturing process, two wafers, that is, a first wafer and a second wafer are electrically connected using the vias of one wafer and the bonding pads of the other wafer. Also, when manufacturing an image sensor through a 3D CIS manufacturing process, two wafers are electrically connected using the vias of both the two wafers.