Low-Stress CMOS-Compatible Silicon Carbide Surface-Micromachining Technology—Part II: Beam Resonators for MEMS Above IC

Microelectromechanical beam resonators and arrays are fabricated using a custom low-temperature complementary-metal-oxide-semiconductor-compatible silicon carbide microfabrication process, detailed in Part I of this paper. Theoretical aspects are presented with modal analysis and numerical methods. Measurements of the resonant frequency, the quality factor, the transmission, and the tuning characteristics are presented for different device types and dimensions. Trends are analyzed, and performance metrics dependences are investigated. A tuning method based on integrated heaters is introduced and tested, yielding a very desirable constant insertion-loss tuning and a wide tuning range. Quality factors of up to 1493 and resonant frequencies of up to 26.2 MHz are demonstrated. Both the Young's modulus and the residual stress of the SiC film are extracted (261 GPa and <; ±30 MPa, respectively), and favorably compare to values reported for polysilicon.