Structural investigations of gold-to-gold wafer bonding interfaces

We have reported the wafer bonding of gold (Au)Au at 400 °C using the simple furnace and have investigated the structural properties of the Au-bonded layer. Scanning electron microscopy indicated that the bonding interface was clear and straight and the average interfacial grain size of Au-bonded layer increased by the wafer bonding. X-ray diffraction revealed that the lattice plane spacings of interfacial grains decreased by the wafer bonding and the bonded Au layer tended to show the (2 2 0) preferred grain orientation.