Damping directly impacts flicker frequency noise of piezoelectric aluminum nitride resonators

This paper presents an analysis on the effect of damping on flicker frequency (1/f) noise of 1.1 GHz aluminum nitride (AlN) contour mode resonators (CMR). A total of 52 different AlN-CMRs are systemically designed and fabricated to give quality factors (Q) ranging from 300 to 3500, allowing the study of how two major damping mechanisms in AlN-CMRs, 1) anchor losses and 2) thermoelastic damping (TED), affect the resonator 1/f noise. In total, we have measured 104 CMRs and the results confirm that 1/f noise shows a clear power law dependence that is close to 1/Q3, independently of the main nature of the damping mechanism. Understanding and accounting for the effect of damping on 1/f noise is crucial for building ultra-low noise Microelectromechanical systems (MEMS) resonators for sensing, timing, and frequency applications.