From Direct Bonding Mechanism to 3D Applications

Nowadays Silicon direct wafer bonding is a mass production technology in many different applications. Starting around the sixties for industrial optical system elaboration, its major development is now in the microelectronic, microtechnology and optoelectronic fields. Obviously to reach such a mature level, the direct bonding mechanisms have to be established. The silicon or silicon dioxide direct bonding is now well established and direct bonding using metallic surfaces starts also to be investigated. For instance, copper or titanium direct bonding mechanism are established. The behavior of hybrid direct bonding using surfaces composed of both materials can then be understood. This hybrid bonding paves the way to high-density interconnection bonding for 3D applications.