Si-SiO2 Composite MEMS Resonators in CMOS Compatible Wafer-scale Thin-Film Encapsulation

Si-SiO₂ composite resonators in wafer-scale thin-film encapsulation are demonstrated. These resonators are fabricated in hermetic wafer-scale thin-film encapsulation, which enables mass production with high yield even after harsh post processes. Also this encapsulation provides potential for integration of frequency references with CMOS circuitry. The encapsulated composite resonators exhibit tunable temperature dependence of resonant frequency with a high quality factor of much larger than 10,000. Up to 40times improvement in temperature stability was demonstrated.