CMOS-MEMS Resonant Transducers for Frequency Control and Sensing

This paper presents CMOS-MEMS fabrication process overview and the use of monolithic integrated devices in the development of frequency control and sensing applications. Post-processing of CMOS wafer can produce oxide-rich resonators that offer high $Q$ and low motional resistance. Frequency stability and transduction efficiency can be further improved by using a TiN-C based process. Both active and passive temperature compensation techniques can be used to fabricate low-power CMOS-MEMS ovenized oscillators that generate highly stable frequency output. Integration of CMOS circuits and MEMS devices can help to realize wide dynamic range pressure sensors, particulate matter (PM 2.5 ) aerosol sensors as well as compact size ultrasound receivers for environmental and biomedical applications.