INTERPOSER INCLUDING A COPPER EDGE SEAL RING STRUCTURE AND METHODS OF FORMING THE SAME

An organic interposer includes interconnect-level dielectric material layers embedding redistribution interconnect structures, package-side bump structures located on a first side of the interconnect-level dielectric material layers, at least one dielectric capping layer located on a second side of the interconnect-level dielectric material layers, a bonding-level dielectric layer located on the at least one dielectric capping layer, metallic pad structures including pad via portions embedded in the at least one dielectric capping layer and pad plate portions embedded in the bonding-level dielectric layer, and an edge seal ring structure vertically extending from a first horizontal plane including bonding surfaces of the package-side bump structures to a second horizontal plane including distal planar surfaces of the metallic pad structures. The edge seal ring structure may include a vertical stack of metallic ring structures that are free of aluminum and laterally surround the package-side bump structures and the redistribution interconnect structures.