Dielectric sensing of silicon accelerometers
Name
870678745-MIT.pdf
Description
Full printable version
Size
13.62 MB
Format
Adobe PDF
Checksum (MD5)
f9af5dab0fde426c3545158bbb4e1dc1
Author(s)
Kroese, Bethany Ruth
Advisor(s)
Dana Weinstein.
Date Issued
2013
Publisher
Massachusetts Institute of Technology
Abstract
Microaccelerometers have established themselves as a vital piece of the global microelectromechanical systems (MEMS) market with applications spanning automotive, industrial, military, biomedical, and consumer electronics sectors. They remain one of the top-selling silicon sensors, with $1.6 billion in revenue reported in 2011 equating to 15% of the total MEMS market. Continued, expected growth in the next few years demands innovation to meet new industry requirements. Current commercial accelerometer designs are based on a differential capacitor structure which measures the change in capacitance between a set of interdigitated fingers. These fingers are separated by air gaps in high aspect ratio, suspended polysilicon microstructures. Despite its widespread use, the air gap capacitor has some significant drawbacks. It involves a release step during fabrication which introduces complexity and variation in the devices. In addition, these transducers are subject to pull in and stiction which can render a device inoperable. Air gap devices are vulnerable to particulates requiring complicated packaging steps which increase cost and yield of production. Moreover, these devices are also subject to electrical drift. All of these issues can be addressed by replacing this air gap with a dielectric. Not only does it mitigate these concerns, it also offers potential for smaller device footprint, more robust design, and increased shock survival. This project developed a new accelerometer design sandwiching a thin film dielectric between two electrodes. This capacitor was patterned on top of a bending flexure which supported a large hanging mass. In the presence of an external acceleration, the deflection of the suspension beams caused a deformation of the dielectric film resulting in a change in capacitance. Fabrication using an SOI substrate allowed for increased deflection and process control.
Description
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 107-108).
Subjects
Electrical Engineering and Computer Science.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Terms of Use
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