Direct metal bonding using nanotwinned Ag films with (1 1 1) surface orientation under air atmosphere for heterogeneous integration

This study proposes to use highly (1 1 1)-oriented nanotwinned Ag films to achieve metal direct bonding under air atmosphere at bonding temperature of 190/200 °C in 3 min. The as-deposited Ag film exhibits strong (1 1 1) surface orientation and high density nanotwinned structure with twin thickness of 8 nm. The bonded samples show a continuous and oxide-free bonding interface. With fastest surface diffusivity on (1 1 1) plane and better mechanical property of nanotwinned structure, the applied bonding pressure can be significantly reduced and exhibit bonding strength over 79.1 MPa. These results provide an alternative concept to achieve high quality interconnections for heterogeneous integration in next generation power devices such as electric vehicles/5G communications.