High q quartz-based mems resonators and methods of fabricating same

Abstract

High-yield fabrication methods are provided for making quartz resonators having thicknesses ranging from one micrometer to several hundred micrometers and thus covering the frequency range from HF to UHF. Plasma dry etching is used to form arbitrary resonator geometries. The quartz resonator structure and the through-quartz vias are formed concurrently. The method includes bonding a quartz device wafer to a quartz handle wafer with a temporary adhesive. Mesa structures formed by plasma dry etching enable the resonators to achieve high-Q operation with energy trapping/mode confinement. A thermo-compression bond integrates the quartz resonators to a host wafer (e.g., an oscillator ASIC) to form oscillators. Silicon cap wafers are bonded over the resonators to the ASIC to provide wafer scale hermetic encapsulation of the quartz oscillators.