the resonance occurs in the mechanical domain. MEMS resonators have already started to use in various applications from wrist watches to the state of the art communications, due to their extremely features. However developing a MEMS resonator with high quality factor in MHz frequency ranges, which would be compatible with CMOS integrated circuits (Dragoi et al. 2012) is very important in view of different applications. In integrated circuits, applications such as filters (Bannon et al. 2000;Lopez et al. 2009), timing and reference frequency devices (Lin et al. 2004;Nguyen 2007), microprocessors (Abdelsalam et al. 2010) and sensors such as pressure and humidity sensors (Shi et al. 2013;Muniraj 2011) facing an important challenge either from scientific or engineering viewpoint that must be well addressed. As an important property, Quality factor (Q) is a scaled ratio between stored energy and damped energy per cycle, which is associated with frequency. In a MEMS resonator, Q is an indication of mechanical energy damping in the system that directly influences sensitivity and resolution of the device Hao et al. 2003). Theoretically, quality factor can be calculated for every frequency, whereas in practice, it is obtained for a specific resonance.In a beam type MEMS resonator, to understand and analyze the energy loss mechanisms, it is important to know the sources of energy loss. The latter could be consisted of support loss, thermoelastic loss and surface loss (Hao et al. 2003). Compression and decompression of an oscillating structure results an irreversible heat flow that is called thermoelastic damping (TED). In Clamped-Clamped (C-C) beam MEMS resonator, the beam in bending experiences a variation on temperature which causes a thermal gradient through the beam. The latter should be well adjusted to maintain the thermal equilibrium. To do this, energy must be intelligently dissipated while the quality factor of the Abstract Thermoelastic damping is one of the dominant mechanisms of structural damping in vacuum-operated microresonators. A three dimensional numerical model based on the finite element method is used for simulating thermoelastic damping in clamped-clamped microelectromechanical beam resonators. In this regards, both simple and slotted beam are considered. To understand the effect of slot positions and sizes on the resonator performance, resonant frequency and thermoelastic quality factor are calculated for both simple and slotted beams for a wide range of beam length from 10 to 400 µm. Punching slots in the resonator beam reduces the stiffness and mass of the beam which affect the resonant frequency. In addition thermomechanical coupling mechanisms of the resonator are affected by the slots which improve the thermoelastic quality factor. For most of the beam lengths, it is shown that the slots at the beam-anchor interface region, where the strain is high, are more effectively enhanced the thermoelastic quality factor than one at the centre of the beam region. However, the highest resonance frequency i...

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Thermoelastic quality factor is an important mechanism for determining quality factor of a microelectromechanical system resonator, which works in near vacuum, and the resonant frequency is an important characteristic of a resonator. This paper studies variations of the thermoelastic quality factor and the resonant frequency of three- and five-slotted clamped-clamped beam microelectromechanical system resonators. The study has been done by using three-dimensional simulations based on finite element method by COMSOL Multiphysics. Resonant frequency is a function of stiffness and mass of the beam, therefore punching slots in the beam changes the resonant frequency. In addition, slots usually decrease the amount of coupling between mechanical resonant mode and thermal modes, thus improve the thermoelastic quality factor. The C–C beam lengths are considered to be 30.5 µm, 100 µm, and 400 µm. The results show the resonant frequency and corresponding thermoelastic quality factor of the three-slotted beams are greater than five-slotted beams, and a maximum resonant frequency of the three-slotted beams is achieved when the length of inner slot is about 32%–36% of the beam length.