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Proceedings Paper

Simulation and optimization of a micromachined gyroscope using high-aspect-ratio micromachining fabrication process
Author(s): Aiwu Y. Ruan; Man Siu Tse; Gang Yih Chong
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Paper Abstract

Micromachined gyroscopes rely on tuned vibration mode frequencies to measure rotation rates and typically have complex modes of vibration for the mechanical microstructures. Although there are many reports on how to exactly tune the drive and sense modes of vibration to maximize sensitivity of micromachined gyroscope, there are only few reports on the detailed analysis of modes of vibration. Modes of vibration are strongly dependent on the design parameters of the mechanical structure of the gyroscope including the dimension of the proof mass, types and dimensions of the suspension, and residual mechanical stress of the high aspect-ratio polysilicon film used to form the microstructures of the micromachined gyroscope. In this paper, an electrostatic drive and capacitive sense in-plane decoupled gyroscope for measuring vertical angular velocity is proposed to study the effects of the geometrical variables on modes of vibration. Finite-element analysis (FEA) simulation was performed on simplifiedmodel of the in-plane decoupled micromachined gyroscope microstructure. For optimal result the drive-mode and sense-mode suspensions of the micromachined gyroscope should be fabricated from thick polysilicon microstructure to give large aspect ratio suspension systems for the in-plane decoupled micromachined gyroscope. Folded-beam suspension design is recommended for the drive-mode suspension in order to relieve the residual stress of the thick polysilicon film for high aspect-ratio micromachine dgyroscope. It is critical to control the process variations of the suspension beam dimension, especially the beam width variation in order to achieve the goal of accurately control resonant frequencies of micromachined gyrocope.

Paper Details

Date Published: 19 November 2001
PDF: 10 pages
Proc. SPIE 4593, Design, Characterization, and Packaging for MEMS and Microelectronics II, (19 November 2001); doi: 10.1117/12.448849
Show Author Affiliations
Aiwu Y. Ruan, Nanyang Technological Univ. (Singapore)
Man Siu Tse, Nanyang Technological Univ. (Singapore)
Gang Yih Chong, Nanyang Technological Univ. (Singapore)

Published in SPIE Proceedings Vol. 4593:
Design, Characterization, and Packaging for MEMS and Microelectronics II
Paul D. Franzon; Ajay P. Malshe; Francis E.H. Tay, Editor(s)

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