(Invited) Room Temperature Bonding Using Thin Metal Films (Bonding Energy and Technical Potential)

Abstract

Room temperature bonding using thin metal films uses two flat wafer surfaces with sputter deposition. Then two films on wafers are bonded in vacuum or in air. Bonding in vacuum can be accomplished using almost any metal film, even with film thickness of a few angstroms on each side. The bonding energy is greater than the surface energy of metal films at thicknesses greater than the critical film thickness, which is related to the formation of thin reactive layers between metal films and wafers. Bonding in air using Au films also shows a bonding energy greater than the surface energy of Au films, even with an exposure time of Au films to air of 168 h (1 week). Bonding of wafers and mirror-polished metals was also achieved, which is effective for enhancing the heat dissipation efficiency.