Reliability of wafer bonding in microsystem technologies

Reliability tests and fracture mechanics models for 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 test approaches for measurement of fracture toughness, crack growth rate and lifetime. It is shown that stress corrosion effects decrease the bonding strength if wafer-bonded interfaces are exposed to a mechanical loading for an extended time. As a consequence the device performance can change or sensors can suddenly fail during application after a load-dependent lifetime.