Room temperature metal direct bonding
A highly scalable room temperature direct bonding in air between aligned metal posts on oxide-covered silicon wafers has been developed. With the help of the forces generated by strong room temperature bonding between oxide layers on mating wafers, the compression forces for thermocompression metal bonding is self-satisfied and no external pressure is required. When the height of the metal extended above the oxide surface is reduced, the width of an unbonded ring around the metal posts is reduced. Interdiffusion and/or self-diffusion of metal atoms at the interface of intimately contacted posts are most likely responsible for forming metallic bonds. A 50 Å thick layer of Au may be deposited on top of the posts to promote electrical connections between posts of almost any metal.