An Electrothermally Actuated Bulk Mode UHF Silicon Resonator

This work presents fabrication and characterization of a bulk-mode thermally actuated silicon resonator with piezoresistive readout. Bulk-modes enable achieving operating frequencies in the UHF range and above without the need to shrink the resonator dimensions deep into the nanoscale. While having the potential to unlock new possibilities, thermal-piezoresistive transduction of bulk resonance modes is associated with challenges that have prevented its demonstration so far. In this work, a dual-block crystalline silicon resonator with 1
^st
bulk mode resonance frequency of 488 MHz has been fabricated and successfully operated utilizing a 200nm × 1μm beam as its electromechanical transducer. Quality factor of 2800 and active motional resistance as low as −150Ω (motional conductance of −6.68 mA/V) has been measured for the fabricated resonator.