Bonded structures and method of forming the same are provided. A conductive layer is formed on a first surface of a bonded structure, the bonded structure including a first substrate bonded to a second substrate, the first surface of the bonded structure being an exposed surface of the first substrate. A patterned mask having first openings and second openings is formed on the conductive layer, the first openings and the second openings exposing portions of the conductive layer. First portions of first bonding connectors are formed in the first openings and first portions of second bonding connectors are formed in the second openings. The conductive layer is patterned to form second portions of the first bonding connectors and second portions of the second bonding connectors. The bonded structure is bonded to a third substrate using the first bonding connectors and the second bonding connectors.