Silicon wafer bonding for encapsulating surface-micromechanical-systems using intermediate glass layers

This paper gives an overview about possibilities for wafer level encapsulation of surface micromachined structures. The particular characteristics of these structures lead to particular requirements regarding wafer bonding technologies. With respect to these requirements and reliability issues, wafer bonding based on intermediate glass layers is found to be suitable for this special application. Especially glass frit bonding offers a lot of advantages when used for the encapsulation of surface micromachined structures. In the present paper this technique is reviewed in detail and an example is given where the technique has been used for the encapsulation of an acceleration sensor.