MEMS monolithic tri-axis high-shock accelerometers with MHz-level ultra-high resonant frequency

This paper reports a novel structure for monolithically integrated tri-axis high-shock accelerometer. All the tri-axial sensors feature ultra-high resonant frequencies, in which the Z-axis accelerometer is no longer a shorter board in design compared to its in-plane X- and Y-axis counterparts. The axially compressed/stretched tiny-beams are connected into Wheatstone-bridge for piezoresistive detection. Processed in ordinary (111) wafers, a low-cost high-yield non-SOI fabrication technique is developed in this study for manufacturing the complicated structure that consists of the axially deformed micro-beams. Being tested under 10000g high-shock acceleration, every of the three accelerometers exhibit 1–2μV/g sensitivity and about 1.5MHz resonant frequency.