Roy Knechtel

Wafer bonding is a key process for microsystems. The results are encapsulated chips as micro-electro-mechanical systems – wafer bonded MEMS. Wafer bonding is a mechanically strong and hermetic mounting of two wafers. Strength and hermeticity must be evaluated either as one-time characterisation, reliability testing, production monitoring or failure analysis. Here it is also interesting to know what happens inside wafer bonded chips – mechanical fractures, corrosion or delamination may occur but are hidden under the cap, inaccessible by optical or electron microscopy. In addition, there is not the one wafer bonding technology, but quite a lot, related to applications. Different methods can be used to analyse and understand the bond interface and what is inside the wafer bonded chip, e.g. infrared and scanning acoustic microscopy to inspect the bond area and internal structures, thermal or mechanical methods to check hermeticity, tensile or shear testing to check bond strength and opening wafer bonded chips for failure analysis, while non-destructive methods are of interest for production monitoring. How to use these methods also as combinations, is the topic of this presentation.

Roy Knechtel is Professor for Autonomous Intelligent Sensors at the University of Applied Sciences Schmalkalden / Germany since 2019, after more than 20 years at X-FAB MEMS Foundry GmbH in various positions. His research interests include sensor principles, multi-sensor integration and sensor applications with a focus on MEMS technologies and wafer bonding processes, which play an important role in realising and improving complex sensor systems. Roy Knechtel holds a Ph.D. in Engineering with focus on Microsystems Technology. He is technical chair and lead organiser of WaferBond – Conference on Wafer Bonding for Microsystems, 3D and Wafer Level Integration.