4H-Silicon Carbide as an Acoustic Material for MEMS

This article discusses the potential of 4H-silicon carbide (SiC) as a superior acoustic material formicroelectromechanical systems (MEMS), particularly forhigh-performance resonator and extreme environmentsapplications. Through a comparison of the crystallinestructure along with the mechanical, acoustic, electrical,and thermal properties of 4H with respect to otherSiC polytypes and silicon, it is shown that 4H-SiCpossesses salient properties for MEMS applications,including its transverse isotropy and small phononscattering dissipation. The utility and implementationof bonded SiC on insulator (4H-SiCOI) substrates asan emerging MEMS technology platform are presented.Additionally, this article reports on the temperature-dependent mechanical properties of 4H-SiC, includingthe temperature coefficient of frequency (TCF) andquality factor (Q-factor) for Lam & eacute; mode resonators.Finally, the 4H-SiC MEMS fabrication including its deepreactive ion etching is discussed. This article providesvaluable insights into the potential of 4H-SiC as amechanoacoustic material and provides a foundation forfuture research in the field.