Effect of metal coating and residual stress on the resonant frequency of MEMS resonators

Pandey, Ashok Kumar and Venkatesh, KP and Pratap, Rudra (2009) Effect of metal coating and residual stress on the resonant frequency of MEMS resonators. In: Sadhana-Academy Proceedings In Engineering Sciences, 34 (4). pp. 651-661.

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Abstract

MEMS resonators are designed for a fixed resonant frequency. Therefore, any shift in the resonant frequency of the final fabricated structure can be a denting factor for its suitability towards a desired application. There are numerous factors which alter the designed resonant frequency of the fabricated resonator such as the metal layer deposited on top of the beam and the residual stresses present in the fabricated structure. While the metal coating, which acts as electrode, increases the stiffness and the effective mass of the composite structure, the residual stress increases or decreases the net stiffness if it is a tensile or compressive type respectively. In this paper, we investigate both these cases by taking two different structures, namely, the micro cantilever beam with gold layer deposited on its top surface and the MEMS gyroscope with residual stresses. First, we carry out experiments to characterize both these structures to find their resonant frequencies. Later, we analytically model those effects and compare them with the experimentally obtained values. Finally, it is found that the analytical models give an error of less than 10% with respect to the experimental results in both the cases.

Item Type:	Journal Article
Publication:	Sadhana-Academy Proceedings In Engineering Sciences
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright for this article belongs to Indian Academy of Sciences.
Keywords:	Resonator; metal coating; residual stress; experimental results; analytical model
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	10 Dec 2009 09:43
Last Modified:	19 Sep 2010 05:52
URI:	http://eprints.iisc.ac.in/id/eprint/24908

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