US Patent 10917602 Stacked imaging device with Cu-Cu bonding portion

An imaging device comprising a pixel substrate including pixel element circuitry, a logic substrate including read circuitry configured to receive an output signal voltage from the pixel element circuitry, and electrically-conductive material arranged between the pixel substrate and the logic substrate, wherein the electrically-conductive material is configured to transfer at least one reference voltage from the logic substrate to the pixel substrate, wherein the electrically-conductive material comprises a Cu—Cu bonding portion.