Low temperature bonding for 3D interconnects

Advanced methods for low temperature bonding are reviewed and discussed in terms of the concept of the surface activation and the future outlook of their development in 3D integration. As one of the methods, a new attempt for room temperature bonding is introduced, which enables to bond inorganic materials such as Si oxides, glasses and sapphire as well as single crystalline piezoelectric materials. The method is based on the concept of the surface activated bonding (SAB) with certain modification including formation of Fe nano-adhesion layer which accompanied by additional Si intermediate layer formed by a special ion beam source. It was found that wafers of such materials can be bonded very strongly without any heat treatment at room temperature.