Composite flexural mode resonator with reduced temperature coefficient of frequency

Abstract

This paper reports a method to passively reduce the native temperature coefficient of frequency (TCF) by creating a Silicon-Silicon Dioxide (Si-SiO2) composite resonator whose bending stiffness has reduced sensitivity to temperature. Silicon exhibits softening with increasing temperature. Amorphous silicon dioxide exhibits an anomalous hardening with increasing temperature. An optimal combination of Si-SiO2 in flexural mode resonators is determined that would yield zero TCF. Composite single anchor, double ended tuning forks (DETF) where fabricated and show a greater than 10x reduction in TCF in the 15°C to 70°C temperature range. The composite beam resonators were fabricated in our wafer-scale encapsulation process, which is described by [1] and is being commercialized.