MEMS Pitch Gyroscope Based on (250-nm)² Gauges Achieving 0.12 °/hr Over 1000 dps Full-Scale

• Published in: Journal of microelectromechanical systems Vol. 33; no. 6; pp. 660 - 667
• Main Authors: Buffoli, Andrea, Gadola, Marco, Robert, Philippe, Langfelder, Giacomo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Attitude (inclination); Coriolis force; Design factors; Gauges; Gyroscopes; Impact analysis; Inertial navigation; MEMS gyroscopes; Microelectromechanical systems; Micromachining; Nanoelectromechanical systems; NEMS; Noise; pitch; Pitch (inclination); Quadratures; roll; Rolling motion; Sensors; Springs; Stability; Stress
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2024.3460401

This document presents a novel architecture of a microelectromechanical system (MEMS) gyroscope for in-plane angular rate sensing (i.e. pitch or roll axis), with a detailed characterization of the performance, including effects of etching nonuniformities and quadrature, which are relevant when dealing with these specific sensing axes. The adopted technology features 20-<inline-formula> <tex-math notation="LaTeX">\mu </tex-math></inline-formula>m-thick frames and springs, and 250-nm-thick and -wide resistive gauges, which are subject to stress under Coriolis-force-induced tilt of a torsional lever. The new design increases by a factor larger than 3 the efficiency of the transduction between tilting of the Coriolis frame inside the gyroscope and corresponding stress on the resistive gauges, in turn improving scale-factor, and bringing noise and stability down to record levels for pitch or roll planar silicon micromachined gyroscopes. At the same time, with respect to a former architecture, a comparative analysis of the impact of the new design choices on the dispersion of the mode-split value is carried out. Results demonstrate that the dispersion increases by a negligible amount, from 36 Hz (old design) to 44 Hz (new design). Most of tested gyroscopes have quadrature value within 5000 dps: however, within a 6-V supply operated board, only part of these sensors could be properly operated under automatic quadrature compensation, reaching under these conditions noise in the range of <inline-formula> <tex-math notation="LaTeX">0.02~^{\circ } </tex-math></inline-formula>/<inline-formula> <tex-math notation="LaTeX">\surd </tex-math></inline-formula>hr and the minimum of the Allan deviation at <inline-formula> <tex-math notation="LaTeX">0.12~^{\circ } </tex-math></inline-formula>/hr.[2024-0124]