Low temperature bonding for 3D integration — A review of the surface activated bonding (SAB)

Advanced methods for low temperature bonding with surface activation and their development for 3D integration are reviewed. A new method for room temperature bonding is introduced, which can bond inorganic materials such as Si oxides, glass and sapphire to each other as well as to polymer films. The method is based on surface activated bonding (SAB) with some modifications including the formation of an Fe nano-adhesion layer accompanied by an additional Si intermediate layer formed by a special ion beam source. It was found that wafers of such materials can be bonded very strongly at room temperature without any heat treatment. The method can be applied also to polymer to polymer bonding without any organic adhesives.