Experimental Investigation of Thermally Induced Nonlinearities in Aluminum Nitride Contour-Mode MEMS Resonators

The aim of this letter is to experimentally demonstrate that the source of amplitude-frequency (
A
-
f
) nonlinearities in aluminum nitride contour-mode MEMS resonators is to be attributed to the softening of the equivalent device Young's modulus due to self-heating effects. Resonators with a center frequency of about 1.16 GHz are here investigated as a case study. The resonator self-heating was evaluated by integrating a platinum serpentine in the resonator body and using it as an efficient temperature sensor. The observations of this work are supported by the comparison of the shift of the
A
-
f
plots measured at different ambient temperatures with the direct recording of the resonator-temperature increase during VNA frequency sweeps.