CMOS-MEMS transverse-mode square plate resonator with high Q and low motional impedance

An integrated CMOS-MEMS transverse-mode square plate resonator centered at 6.52 MHz has been demonstrated with Q´s ranging from 800 to 1,900, and specifically with the lowest motional impedance of 35 kΩ compared to any other CMOS-MEMS counterparts to date by the combination of large transduction area and pull-in mechanism to achieve deep-submicron electrode-to-resonator gap spacing using a foundry-oriented CMOS-MEMS process. In addition, such a resonator is formed by metal/oxide composite structure where the residual stress often seen in CMOS layers is greatly alleviated and where SiO₂ with positive temperature coefficient of Young´s Modulus (TC_E) offers an effective temperature compensation scheme, therefore greatly improving its thermal stability as compared with mere-metal resonators under the same fabrication technologies.