This paper presents the design principles and fabrication techniques for simultaneously forming non-coplanar resonant beams and crab-leg supporting beams of dual-axis bulk micromachined resonant accelerometers by masked-maskless combined anisotropic etching. Four resonant beams are located at the surface of a silicon substrate, whereas the gravity centre of a proof mass lies within the neutral plane of four crab-leg supporting beams on the same substrate. Compared with early reported mechanical structures, the simple structure not only eliminates the bending moments caused by in-plane acceleration, and thereby avoiding the rotation of the proof mass, but also providing sufficiently small rigidity to X and Y axes accelerations, potentially leading to a large sensitivity for measuring the in-plane acceleration.

关键词： Resonant accelerometer,  Maskless etching,  Bulk micromachining technology,  Microelectromechanical system (MEMS),  Microsensor