Uncooled thermal imaging based on micromachined bolometers was pioneered in the 1990s with seminal work at Honeywell. Since then several companies have successfully introduced uncooled infrared imagers for various applications such as night-vision driving assistance, thermography and intrusion detection. However, despite being cheaper than their cryogenically cooled counterparts, uncooled bolometers are still too expensive (>$1k) to find their place in every car or home. In this work, we propose an impedance-matched self-supported metal bolometer as an attempt to enable significantly cheaper devices with similar performance. The most significant challenge in our approach is the fabrication of flat suspended metal pixels tens of microns in length and only a few nanometers in thickness. To overcome this challenge, we rely on the enabling technology that is atomic layer deposition (ALD). This deposition technique was invented decades ago but only recently found its way in mass production, in the latest CMOS technology nodes. Being introduced by the “elder-industry”, ALD is now gaining growing interest in the Microelectromechanical Systems (MEMS) community. Our bolometer concept is enabled by key features of ALD such as its ability to deposit high quality, low-stress films on high-topography substrates at low-temperatures. After describing our bolometer concept and atomic-layer deposition as a technology, early results will be presented as well as challenges that are yet to be solved.
Matthieu Liger received his BS degree in electrical engineering from the Ecole Superieure d’Ingenieurs en Electronique et Electrotechnique in 2001, and his PhD in Electrical Engineering from the California Institute of Technology in 2006. He then joined the Robert Bosch Research and Technology Center in Palo Alto, CA as a research member working on topics such as piezoelectric sensing and adhesion in MEMS together with academic partners in the area. His recent research interest include the applications of atomic-layer deposition in MEMS sensors and actuators. Since 2008 he has been a visiting scholar in the Mechanical Engineering department at Stanford university. Matthieu has also been a member of the MEMS Industry Group (MIG) governing council board since 2007, re-elected in 2009.