10 March 1999 Stress-induced curvature engineering in surface-micromachined devices
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Proceedings Volume 3680, Design, Test, and Microfabrication of MEMS and MOEMS; (1999) https://doi.org/10.1117/12.341167
Event: Design, Test, and Microfabrication of MEMS/MOEMS, 1999, Paris, France
Residual stress and stress gradients play an important role in determining equilibrium shape and behavior of various Si surface-micromachined devices under applied loads. This is particularly true for system having large-area plates and long beams where curvature resulting from stress can lead to significant deviations from stress-free shape. To gain better understanding of these properties, we have measured the equilibrium shapes of various structures built on the MCNC MUMPs using an interferometric profiler. The structures were square plates and long beams composed of various combinations of polysilicon an oxide layers. Some of the structures had additional MUMPs metal layer on top, while on others in-house chromium-gold stacks of varying thickness have been deposited. Temperature dependence of the curvature was measured for some plates. We have used these data in conjunction with simple models to significantly improve the performance of our micromachined devices. While for some structures such as large area reflectors the curvature had to be minimized, it could be advantageously exploited by others, for example vertical actuators for self-assembly.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Vladimir A. Aksyuk, Flavio Pardo, David J. Bishop, "Stress-induced curvature engineering in surface-micromachined devices", Proc. SPIE 3680, Design, Test, and Microfabrication of MEMS and MOEMS, (10 March 1999); doi: 10.1117/12.341167; https://doi.org/10.1117/12.341167

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