Monolithic Sensor Integration in CMOS Technologies

Besides being mainstream for mixed-signal electronics, CMOS technology can be used to integrate micro-electromechanical system (MEMS) on a single die, taking advantage of the structures and materials available in feature sizes around 180 nm. In this article, we demonstrate that the CMOS back-end-of-line (BEOL) layers can be postprocessed and be opportunistically used to create several kinds of MEMS sensors exhibiting good or even excellent performance, such as accelerometers, pressure sensors, and magnetometers. Despite the limitations of the available mechanical and material properties in CMOS technology, due to monolithic integration, these are compensated by the significant reduction of parasitics and system size. Furthermore, this work opens the path to create monolithic integrated multisensor (and even actuator) chips, including data fusion and intelligent processing.