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Proceedings Paper

Stiction force estimation from attachment length and electrostatic measurements on cantilever beams
Author(s): Enakshi Bhattacharya; Souvik Basu; Anil Prabhakar
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Paper Abstract

An estimate of stiction force, rather than the more commonly reported surface energy, helps design reliable structures. Stiction is a major cause of failure in surface micromachined structures. We report on the modeling and estimation of the stiction force from simple I-V curves on cantilever beams which can be measured even on packaged devices. We have fabricated oxide anchored cantilever beams of polysilicon by surface micromachining. Current is measured for an applied bias between the beam and the substrate. Pull-in and pull-out voltages are determined as the points of maximum slope calculated by differentiating a cubic spline fit to the measured I-V data. The commercial package CoventorWare was used to develop an empirical model for estimating the pull-out voltage for the cases when there is no stiction and in the presence of stiction. A model is developed for finding the stiction force from the simulated and the experimental pull-out voltages. The method uses only measured values of pull-in and pull-out voltages and the beam length and does not require the value of Young's modulus. We also discuss an independent visual method to estimate the process stiction force from the cantilever beam array that is normally used to estimate the surface adhesive energy. An analytical model is developed to calculate the stiction force from the attachment length of long stuck cantilever beams that are released in the same process.

Paper Details

Date Published: 5 January 2006
PDF: 14 pages
Proc. SPIE 6111, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS V, 611101 (5 January 2006); doi: 10.1117/12.640506
Show Author Affiliations
Enakshi Bhattacharya, Indian Institute of Technology Madras (India)
Souvik Basu, Indian Institute of Technology Madras (India)
Anil Prabhakar, Indian Institute of Technology Madras (India)


Published in SPIE Proceedings Vol. 6111:
Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS V
Danelle M. Tanner; Rajeshuni Ramesham, Editor(s)

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