Piezoelectrically Transduced Temperature-Compensated Flexural-Mode Silicon Resonators

Temperature compensated silicon resonators for space applications

“…Capacitively actuated IBARs with Qs exceeding 100,000 have been reported previously [20], [21]. In a recent work [19], we demonstrated piezoelectric actuation of an IBAR in order to improve the motional impedance and obviate the fabrication complexity required to make narrow electrostatic actuation gaps. In order to resonate the IBAR in an in-plane flexural mode, the RF signal is applied to the input electrodes across both the flanges ( Fig.…”

“…and are the width and the length of the resonating flange. In [19], we demonstrated that the TCF of AlN-on-silicon resonators can be reduced using oxide-refilled trenches (shown as green boxes in Fig. 1(a)) and the position of these oxide trenches has a direct impact on the final TCF value.…”

“…From these simulation results, we can find that the regions of high stress are near the device edges in case of flexural modes. By placing oxide-refilled trenches close to the resonator edge, where strain energy is high, efficient temperature compensation can be achieved [19]. In this work we explore the tunability of the turnover temperature through oxide-refilled trench size modifications.…”

“…A passive TCF compensation strategy utilizing oxide pillars uniformly distributed through the resonator was demonstrated in [18]. In order to make the fabrication compatible with wet release processes, we have recently implemented oxide-refilled trenches within the silicon resonator body to efficiently reduce the TCF [19]. We demonstrated that the position of the oxide-refilled trenches in the resonator body is critical towards maximizing temperature compensation with minimum material deposition and minimum Q degradation.…”

“…Using this TCF compensation technique, we demonstrated resonators with short term frequency drift in the order of 100 ppb [19]. In order to understand the cause of this frequency drift, we measure the stability of these resonators at their turnover temperature and at room temperature.…”