This paper presents a new approach for the fabrication of a three-axis capacitive MEMS accelerometer that is capable of differentially sensing the acceleration in all three orthogonal axes. For the first time in literature, differential sensing for the out of plane direction is achieved by defining a movable sensing electrode on the structural layer of the SOI wafer that is sandwiched between two stationary electrodes defined on the glass substrate and the handle layer of the SOI wafer enabling the differential sensing. In this approach, individual lateral and vertical axis accelerometers are fabricated in the same die on an SOI wafer which is anodically bonded to a glass substrate.
Aydemir, A., & Akin, T. (2015). Process development for the fabrication of a three axes capacitive MEMS accelerometer. In Procedia Engineering (Vol. 120, pp. 727–730). Elsevier Ltd. https://doi.org/10.1016/j.proeng.2015.08.773