Strength and long-term reliability testing of wafer-bonded MEMS

Wafer bonding techniques are frequently used for MEMS/MOEMS fabrication. In this paper, the potential application and methodical limitations of different strength testing approaches including tensile testing and double-cantilever-beam testing for wafer-bonded components are investigated. Special attention is given to the influence of the interfacial atomic bonding strength, the role of interface voids and notches caused by chemical or physical etching steps prior to bonding on the fracture limit. A particular aim of the paper is to discuss the potential of the Micro Chevron-Test for the assessment of the wafer bonding process with particular respect to the quality control during MEMS fabrication. In addition, the methods can also be applied to investigate the lifetime and fatigue properties of wafer-bonded samples exposed to constant or cyclic stresses.