Quality and mechanical reliability assessment of wafer-bonded micromechanical components

Strength tests and fracture mechanics models for Silicon wafer-bonded components are presented which can be applied during the development of bonding technologies, for the yield improvement and failure analysis as well as for the reliability assessment of micromechanical sensors and actuators. Special attention is given to the influences of atomic bonding strength, the interface voids and the notches caused by etching steps prior to bonding on the fracture limit. If wafer-bonded interfaces are exposed to a mechanical loading for an extended time, e.g. in the order of months or years, stress corrosion effects decrease the bonding strength. As a consequence, stressed sensors and actuators fabricated by wafer bonding can suddenly fail during application after a load-dependent lifetime. Based on an appropriate fracture mechanics model, the time-to-failure data could be theoretically predicted. © 1999 Elsevier Science Ltd. All rights reserved.