5V-Bias Cmos-Mems Capacitive Resonator with RM< 5KO Based on Metal-Insulator-Metal (Mim) Capacitor

Abstract

This work presents a flexural mode capacitive resonator with a 125nm effective transduction gap in a 0.18m CMOS technology node by implementing a three-step post-fabrication process on an MIM capacitor without any additional lithography step. The proposed resonator achieves motional resistance of 4.6kO under only 5V bias and realizes a record-low value of 1.45kO at 10V bias. At 11V bias, the resonator shows a coupling strength (Cm/Co) of 29% with a 23% frequency shift referenced to a 2V bias condition. In addition to the MIM resonator, a TiN-C capacitive resonator originally fabricated in the traditional 0.35m CMOS platform from our previous work [1] is also successfully transferred into the 0.18m CMOS platform with an effective gap of 450nm for comparison. Finally, a monolithic MEMS-CMOS integrated system is demonstrated, and a nonlinear phenomenon is observed for the proposed MIM resonators.