Design and Fabrication of a Slanted-Beam MEMS Accelerometer

作者:Xu, Wei*; Yang, Jie; Xie, Guofen; Wang, Bin; Qu, Mingshan; Wang, Xuguang; Liu, Xianxue; Tang, Bin
来源:Micromachines, 2017, 8(3): 77.
DOI:10.3390/mi8030077

摘要

This paper presents a novel capacitive microelectromechanical systems (MEMS) accelerometer with slanted supporting beams and all-silicon sandwich structure. Its sensing mechanism is quite similar to an ordinary sandwich-type MEMS accelerometer, except that its proof mass is suspended by a beam parallel to the {111} plane of a (100) silicon wafer. In this way, each sensing element can detect accelerations in two orthogonal directions. Four of these sensing elements could work together and constitute a 3-axis micro-accelerometer by using a simple planar assembly process. This design avoids the traditional 3-axis accelerometer' disadvantage of possible placement inaccuracy when assembling on three different planes and largely reduces the package volume. The slanted-beam accelerometer's performance was modeled and analyzed by using both analytical calculations and finite element method (FEM) simulations. A prototype of one sensing element was fabricated and tested. Measured results show that this accelerometer has a good bias stability 76.8 ppm (1 sigma, tested immediately after power on), two directional sensitivities (sensitivity angle alpha = 45.4 degrees) and low nonlinearity (<0.5%) over a sensing range up to +/- 50 g, which demonstrates a great opportunity for future high-precision three-axis inertial measurement.