CMOS Integrated Stress Sensor Systems for Force and Torque Sensing and Packaging Reliability Monitoring

Department of Microsystems Engineering (IMTEK) University of Freiburg, Germany
The talk will present novel developments in the author&rquo;s group on microsensors and microsystems based on complementary metal oxide semiconductor (CMOS) technology for measuring mechanical stress and applications of these devices and systems. The stress acting on the sensors may originate from effects internal or external to the package of the sensor chip. In a first application area, therefore, the sensors have proven useful for the measurement of thermomechanical forces acting on encapsulated microchips and thus for studying the reliability of advanced microelectronic packaging technologies. Secondly, the systems make it possible to measure external mechanical constraints such as forces and moments. Recently developed sensors and systems for this application category include tactile sensors, smart brackets, and a solid-state-only joystick with four degrees of freedom, among others. The systems implemented in these applications rely on sensors for in-plane stresses. For packaging testing applications, in addition, devices sensitive to out-of-plane stress components have to be developed. First examples of such sensors and corresponding results will be presented. A brief excursion into the in-situ calibration of the devices will round off the picture.
Oliver Paul received the Diploma in physics and the D.Sc. degree from the Swiss Federal Institute of Technology (ETH), Zurich, Switzerland, in 1986 and 1990, respectively. After his postdoctoral work with the Fraunhofer Institute for Solar Energy Systems, Freiburg, Germany, where he contributed to the technology and modeling of high-efficiency silicon solar cells, he joined the Physical Electronics Laboratory, ETH, as a Lecturer and Group Leader in 1992. Since 1998, he has been a Full Professor with the University of Freiburg, Germany, where he heads the Microsystem Materials Laboratory at the Department of Microsystems Engineering (IMTEK). From 2006 to 2008, he served as the Director of IMTEK. His group’s research focuses on MEMS materials and fabrication technologies, physical microtransducers and microsystems, and microstructures for industrial and life science applications. He also heads the Ph.D. program “Embedded Microsystems” at the University of Freiburg. He is a cofounder of the MEMS company Sensirion AG. He is the coauthor of more than 200 technical publications and four books and is the holder of three patents. He is a member of the Editorial boards of Sensors and Actuators A and Journal of Micromechanics and Microengineering and of the Editorial Advisory Board of the IEEJ Transactions on Electrical and Electronic Engineering. Prof. Paul co-chaired the IEEE MEMS 2004 Conference, Maastricht, The Netherlands, January 25–29, 2004.