Quality factor of MEMS and NEMS AlN Contour Mode Resonators in liquid media

Miniaturized resonant sensors for biological applications are required to operate in liquids and their quality factor (Q) is important in setting their limit of detection. This work presents the first theoretical analysis and experimental verification of the behavior of AlN Contour Mode M/NEMS Resonators (CMRs) in liquids. CMRs are based on in-plane lateral vibrations and therefore deemed to perform well in liquids, similarly to shear-based devices. This study shows that the Q in water of four 250 nm thick AlN CMRs with different frequencies of operation on the same silicon die (182 MHz to 3.45 GHz) increases with frequency (up to 90 at 3.45 GHz) in agreement with the theory and is independent of the device surface area. Therefore, miniaturization and frequency scaling of AlN CMRs can be advantageously exploited to operate in liquids.