Rearrangement of crystal lattice at a Ag/Ag and Au/Au bonded interface in atomic diffusion bonding

This study examines atomic diffusion bonding (ADB) of wafers using Ag and Au films in vacuum at room temperature. Transmission electron microscopic images show remarkable crystal lattice rearrangement that occurs at depths greater than 50 nm from the connected Ag/Ag film interface. The Au/Au interface fluctuation attributable to the crystal lattice rearrangement is 5-10 nm. X-ray diffraction reveals that the crystal lattice rearrangement for Ag/Ag interface occurs remarkably at thicknesses of less than 150 nm, indicating high bonding potential when using Ag films in ADB. Large surface roughness in the thick film region probably suppresses the crystal lattice rearrangement.