Small footprint, high-performance silicon capacitive accelerometer with a 3-D process

A new process for multi-layer MEMS is presented and demonstrated with an in-plane accelerometer. With this solution, sensing elements (here, comb-fingers) and seismic mass can be fabricated in different layers and located on top of each other for a significantly reduced footprint and enhanced performance: both can be independently optimized. For this first demonstration, we show an intrinsic noise floor of 7 μg/√Hz mechanical stiffness of 20 N/m, large bandwidth and a sensitivity of 5.3 fF/g with a total footprint of 400μm×600μm.