A front-side non-soi fabricated tri-axis capacitive accelerometer with electromechanical sigma-delta modulators interface

This paper presents a novel front-side non-SOI fabricated tri-axis capacitive accelerometer with a dual quantization electromechanical sigma-delta modulator (EM-ΣΔΜ) interface. It can be used for realizing monolithic inertial microsystem units. The 2.6mm×2.6mm sized tri-axis accelerometer is designed and fabricated with a high-yield bulk-micromachining fabrication process using only front-side etching of a 4-inch (111) silicon wafer. The process is fully IC-compatible. The interface circuit is based on a low-noise front-end ASIC and a back-end dual quantization EM-ΣΔΜ digital circuit implemented in an FPGA. Acceleration sensitivities of 170mV/g and 26mV/g were measured for the in-plane (X/Y-axis) and out-of-plane (Z-axis), respectively. The cross-axis sensitivity was in the order of 1% to 3%. The output noise was in the order of 2mg to 6mg/ √ Hz, with a one hour bias drift of 3mg to 6mg. © 2017 IEEE.