High-Q monocrystalline silicon carbide disk resonators fabricated using drie of thick SiC-on-insulator substrates

Abstract

This paper presents, for the first time, high-Q bulk acoustic wave (BAW) modes in disk resonators fabricated using deep reactive ion etching (DRIE) of custom-made 100μm-thick 4H-single crystal silicon carbide-on-insulator (SiCOI) substrates. With SiC exhibiting the lowest intrinsic Akhiezer loss among all common resonator materials (Akhiezer f·Q=6.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> Hz), bonded SiCOI substrates are ideal to demonstrate resonant BAW gyroscopes with ultra-high mechanical Q-factors while operating in harsh environments. Front-side perforations, introduced for release purposes in the SiC layer, define the as-fabricated frequency split (Δf=215Hz) of the secondary elliptical modes (m=3) and its Q-factor (Q=170k at 843kHz), which is the highest reported for SiC disk resonators.