A HIGH-Q SOLID DISK BAW GYROSCOPE IN MONOCRYSTALLINE 4H SILICON-CARBIDE WITH SUB-PPM AS-BORN FREQUENCY SPLIT

This paper demonstrates, for the first time, a solid disk capacitive bulk-acoustic wave (BAW) gyroscope in monocrystalline 4H-SiC, with a promising angle random walk of 0.03/h, fabricated at wafer level using DRIE of a bonded SiC-on-Insulator (SiCOI) substrate.The 3MHz gyroscope operates in m=3 elliptical mode with a very small as-born frequency split of sub-ppm owing to the excellent in-plane isotropic lattice of 4H-SiC.Statistical data of resonator characterization across the 4-inch SiCOI wafer is reported, showing consistently small frequency splits and high Q factors, uncommon in Si substrates.The cross-coupling between two gyroscopic modes is compensated via electrostatic spring softening, while the 3mm disk resonator is driven to >300nm amplitude, paving the way towards the development of highperformance SiC BAW gyroscopes.