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Self-tensioning Support Post Design to Control Residual Stress in MEMS Fixed-Fixed Beams

Published online by Cambridge University Press:  22 January 2014

Ryan M. Pocratsky  and
Maarten P. de Boer
Ryan M. Pocratsky
Affiliation:
Carnegie Mellon University, Dept. of Mechanical Engineering, 5000 Forbes Avenue, Pittsburgh, PA 15235, U.S.A.
Maarten P. de Boer
Affiliation:
Carnegie Mellon University, Dept. of Mechanical Engineering, 5000 Forbes Avenue, Pittsburgh, PA 15235, U.S.A.
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Abstract

Fixed-fixed beams are ubiquitous MEMS structures that are integral components for sensors and actuation mechanisms. However, residual stress inherent in surface micromachining can affect the mechanical behavior of fixed-fixed structures, and even can cause buckling. A self-tensioning support post design that utilizes the compressive residual stress of trapped sacrificial oxide to control the stress state passively and locally in a fixed-fixed beam is proposed and detailed. The thickness and length of the trapped oxide affects the amount of stress in the beam. With this design, compression can be reduced or even converted into tension. An analytical model and a 3D finite element model are presented. The analytical model shows relatively good agreement with a 3D finite element model, indicating that it can be used for design purposes. A series of fixed-fixed beams were fabricated to demonstrate that the tensioning support post causes a reduction in buckling amplitude, even pulling the beam into tension. Phase shifting interferometry deflection measurements were used to confirm the trends observed from the models. Controlling residual stress allows longer fixed-fixed beams to be fabricated without buckling, which can improve the performance range of sensors. This technique can also enable local stress control, which is important for sensors.

Keywords

microelectro-mechanical (MEMS)thin filmdevices
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1659: Symposium SS/XX – Micro- and Nanoscale Systems – Novel Materials, Structures and Devices , 2014 , pp. 55 - 61
Copyright
Copyright © Materials Research Society 2014 

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References

REFERENCES

Hocker, G. B., Youngner, D., Butler, M., Sinclair, M., Plowman, T., Deutsch, E., Volpicelli, A., Senturia, S., and Ricco, A. J., “The Polychromator: a programmable MEMS diffraction grating for synthetic spectra,” Proc. Solid-State Sensor and Actuator Workshop, Hilton Head, SC, June 4-8, 2000.Google Scholar
Huff, M. A., Nikolich, A. D., and Schmidt, M. A., “A threshold pressure switch utilizing plastic deformation of silicon,” International Conference Solid-State Sensor and Actuators, 1991, pp. 177–180.Google Scholar
Popescu, D. S., Dascalu, D. C., Elwenspoek, M., and Lammerink, T., “Silicon active microvalves using buckled membranes for actuation,” International Conference Solid-State Sensors and Actuators, Stockholm, Sweden, June 25-29, 1995, pp. 305–308.Google Scholar
Goldsmith, C. L., Yao, Z., Eshelman, S., and Denniston, D., “Performance of low-loss RF MEMS capacitive switches,” IEEE Microwave and Guided Wave Letters, Vol. 8, No. 8, August 1998, pp. 269–271.CrossRefGoogle Scholar
Liao, C.d., and Tsai, J.C., “The evolution of MEMS displays,” IEEE Trans. On Industrial Electronics, Vol. 56., No. 4, April 2009, pp. 1057–1065.CrossRefGoogle Scholar
Iwase, E., Hui, P.C., Woolf, D., Rodriguez, A. W., Johnson, S. G., Capasso, F., and Loncar, M., “Control of buckling in large micromembranes using engineered support structures,” J. Micromech. Microeng. 22(6), 2012.CrossRefGoogle Scholar
Hassanpour, P. A., Nieva, P. M., and Khajepour, A., “A passive mechanism for thermal stress regulation in micro-machined beam-type structures,” Microsyst. Technol., Vol 18., No. 5, 2012, pp. 543–556.CrossRefGoogle Scholar
Sze, S. M., VLSI Technology. New York: McGraw-Hill, 1983.Google Scholar
Masters, N.D., de Boer, M. P., Jensen, B.D., Baker, M.S., and Koester, D., “Side-by-side comparison of passive mems strain test structures under residual compression,” ASTM STP 1413, 2001, pp. 168–200.Google Scholar
Jensen, B. D., de Boer, M. P., and Miller, S. L., “IMAP: Interferometry for material property measurement in MEMS,” MSM ’99, vol., San Juan, Puerto Rico, 1999, pp. 206–209.Google Scholar