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Proceedings Paper

Novel silicon cap package technology for monolithic microinertial measurement unit
Author(s): Zhihong Li; Dacheng Zhang; Yilong Hao; Ting Li; Ying Wang; Guoying Wu
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Paper Abstract

A monolithic micromachined inertial measurement unit (IMU), which combines three-degree-of-freedom gyroscope and a three-degree-of-freedom accelerometer, is attractive for navigation and guidance. A micromachined gyroscope generally works in a vacuum package to archive a high resolution. By contraries, a package of an accelerometer should provide proper dumping to optimize dynamic response. It is very difficult to fulfill two different package demands in one chip by using conventional package technology. We developed wafer-level silicon cap package technology to solve the problem. The gyroscope is completely sealed in a vacuum silicon cavity by anodic bonding in vacuum. The accelerometer is package din another silicon cavity, but different from the gyroscope, a 'bypass hole' is fabricated in the wall of the cavity. Using this technique, the accelerometer can operate in an air ambient, the damping is controlled by optimizing structure design of accelerometer and change the size of the bypass hole. Consequently, demands of package for both accelerometer and gyroscope are fulfilled. Besides, the silicon cap can protect fragile mechanical structures during post-releasing processing, such as dicing, mounting and wire bonding. Consequently, after the silicon cap is formed, the MEMS wafer can be treated as a common IC wafer. These structures were fabricated with wafer bonding and ICP deep etching technologies, but can be also fabricated by other micromachining technologies.

Paper Details

Date Published: 21 June 2000
PDF: 8 pages
Proc. SPIE 3990, Smart Structures and Materials 2000: Smart Electronics and MEMS, (21 June 2000); doi: 10.1117/12.388914
Show Author Affiliations
Zhihong Li, Peking Univ. (China)
Dacheng Zhang, Peking Univ. (China)
Yilong Hao, Peking Univ. (China)
Ting Li, Peking Univ. (China)
Ying Wang, Peking Univ. (China)
Guoying Wu, Peking Univ. (China)

Published in SPIE Proceedings Vol. 3990:
Smart Structures and Materials 2000: Smart Electronics and MEMS
Vijay K. Varadan, Editor(s)

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