Direct transfer of atomically smooth Au film onto electroplated patterns for room-temperature Au-Au bonding in atmospheric air

We demonstrate a direct transfer technique of Au thin layer onto electroplated Au surface from a surface of atomically smooth master wafer. An atomically smooth Au surface with a root mean square surface roughness of 0.6 nm could be transferred from the master wafer. We also examined its applicability to room-temperature Au-Au bonding in atmosphere. A high bonding strength of about 225 MPa was obtained.