Patent ID: 11205635

Abstract:
Devices and techniques including process steps make use of recesses in conductive interconnect structures to form reliable low temperature metallic bonds. A fill layer is deposited into the recesses prior to bonding. The fill layer is composed of noble metal (such as copper) and active metal (such as Zn). Then the fill metal layer is turned into a metal alloy after annealing. A dealloying is performed to the metal alloy to remove the active metal from the metal alloy while the noble metal remains to self-assemble into porous (nanoporous) structure metal. First conductive interconnect structures are bonded at ambient temperatures to second metallic interconnect structures using dielectric-to-dielectric direct bonding techniques, with the fill nanoporous metal layer in the recesses in one of the first and second interconnect structures. After the following batch annealing, the fill nanoporous metal layer turns into pure bulk metal same as conductive interconnect structures due to the heat expansion of conductive interconnect structures and nanoporous metal densification.