Thermoelastic damping (TED) is an inherent energy dissipation mechanism in micromechanical resonators which imposes an upper limit on the quality factor. Micromechanical resonators with very high quality factors are essential for many applications. Electrostatic actuation is a very common mode of actuation for microresonators and microstructures (referred to as electrostatic microelectromechanical systems). The nonlinear electrostatic actuation force can significantly alter the nature of thermoelastic damping, and hence the quality factor QTED of the microstructures, from that predicted by the classical theory of thermoelastic damping developed by Zener [Phys. Rev. 52, 230 (1937); 53, 90 (1938)] and later improved by Lifshitz and Roukes [Phys. Rev. B 61, 5600 (2000)]. In this paper, the classical theory of thermoelastic damping is modified for application to microstructures under arbitrary electrostatic actuation. The higher-order harmonics of the excitation frequency, which can be present in the oscillations due to the nonlinear nature of the electrostatic force, are taken into account in the modified theory. A physical level simulation tool is also developed in this paper based on coupled electrostatic, fluidic, and large-deformation thermoelastic analysis and validated by comparing with experimental data. The simulation results from the physical level analysis are compared with the predictions of the classical theory and the modified theory under electrostatic actuation. While significant differences (both quantitative and qualitative) are observed in the thermoelastic quality factor QTED obtained from the physical level simulations and the classical theory, the modified theory is in close agreement with the physical level analysis for the entire range of excitation frequencies considered.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 2006|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics