SOI-based HF and VHF single-crystal silicon resonators with SUB-100 nanometer vertical capacitive gaps

This paper reports on the fabrication and characterization of single-crystal silicon (SCS) capacitive resonators with operating frequencies in the HF (3-30 MHz) and VHF (30-300 MHz) range. In-plane ultra-stiff SCS resonators with polysilicon electrodes and self-aligned 90 nm vertical capacitive gaps have been fabricated on SOI substrates using a HARPSS-like fabrication process. High frequency side-supported flexural disk resonators and clamped-clamped beam resonators have been implemented and tested. A 3 /spl mu/m thick, 30/spl mu/m in diameter SCS disk resonator exhibited a quality factor of 40,000 in vacuum at 148 MHz. When operated in atmosphere, the same device demonstrated a Q of 8,000.