Design, Optimization, and Realization of a High-Performance MOEMS Accelerometer From a Double-Device-Layer SOI Wafer

An ultrasensitive single-axis out-of-plane micro optical electro mechanical system (MOEMS) accelerometer with a relatively low cross-axis sensitivity based on a designated micromachined sensing structure and grating interferometry cavity is proposed. While seeking to achieve high performances, we investigated and optimized the design of the mechanical structure, with tensile stress in the flexure close to the ultimate yield strength of monocrystalline silicon. Expressions for acceleration-displacement sensitivity are given and compared with the results of finite-element-method simulations. The highly symmetric accelerometer was fabricated through a particular fabrication process on a specific double-device-layer silicon-oninsulate wafer. The acceleration-displacement sensitivity of the optimal sensing structure, as obtained from static acceleration measurement, was 158.20 μm/g and outperforms its previously reported counterparts. Experimental results revealed that the MOEMS accelerometer with an optimal design achieved an acceleration sensitivity of 2485 V/g with a resonant frequency of 34.5 Hz and a noise level of 185.8 ng/(Hz)
^0.5
, corresponding to a resolution of 1 μg, as well as a cross-axis sensitivity of 3.48%/0.1 g, which is one order smaller than the conventional one. The proposed design may pave the way for the applications that require extremely high sensitivity, low cross-axis sensitivity, and comparatively low-frequency response, such as seismology and microgravity detection.