Internal Dielectric Transduction in Bulk-Mode Resonators

This paper investigates electrostatic transduction of a longitudinal-mode silicon acoustic resonator with internal dielectric films. Geometric optimization of internal dielectrically transduced resonators is derived analytically and shown experimentally. Analysis of internal dielectric transduction shows a maximum transduction efficiency with thin dielectric films at points of maximum strain of the desired resonant mode. With this design optimization, a silicon bar resonator is realized with a ninth harmonic resonance of 4.5 GHz and a quality factor of over 11 000, resulting in a record high f middotQ product in silicon of 5.1 times 10¹³. The novel dielectric transducer demonstrates improved resonator performance with increasing frequency, with optimal transduction efficiency when the acoustic wavelength is twice the dielectric thickness. Such frequency scaling behavior enables the realization of resonators up to the super-high-frequency domain.