Optimization of a CMOS-MEMS Resonator for Applications of Relative Humidity Measurement

The mathematical modeling and the finite element analysis (FEA) of a Complementary
Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) resonator
has been presented. The resonator is designed based on 0.35 µm CMOS foundry
fabrication technology. The sensing principle of the resonator is based on the change in
resonance frequency of the CMOS-MEMS resonator due to adsorption/absorption or
desorption of humidity on the active material layer of deposited on the moving plate that
results in changes in the mass of the device. Simple analytical models of the CMOSMEMS resonator are generated to achieve estimates of the device performs. The effect of
changes in lengths and widths of the beams on spring constant, resonance frequency,
damping coefficient and quality factor (Q) are investigated. The spring constant is found
to decrease with increase the lengths of the beam and increasing with increase the widths
of the beam.