Highly decoupled single-crystal silicon resonators: an approach for the intrinsic quality factor

Special attention has been paid in this work to use all possible means to measure an intrinsic quality factor (Q) for silicon beam resonators realized on SOI wafers. Specifically, this work points to the energy dissipation into the support; a model is given and a high insulating system for clamped–clamped and clamped-free configurations has been studied, preserving the resonating element from support damping. Finite element analysis on these structures evidences values of Qsupport higher than 107. Out-of-plane and in-plane vibration Q values up to 1.0 × 105 have been measured under a high vacuum using, respectively, laser Doppler vibrometry and stroboscopic optical microscopy combined with image processing. The results have shown good agreement with thermoelastic theory. However, the observed agreement on the resonator dimension dependences is limited to quality factors lower than 3.0 × 104. Beyond these values, a physical limitation is evidenced in both cases (in-plane and out-of-plane) which does not match with the surface and clamping models listed. The role of the SOI wafer's oxide layer is discussed as a possible source of dissipation.