Capacitive Length-Extension Mode Resonators with Stress-Induced Gap-Closing Electrodes for Motional Resistance Reduction

This work presents a capacitive length-extension mode resonator featuring novel gap-closing electrodes, which apply nonuniform stress to the structure of the movable electrodes to reduce the capacitive transduction gaps to sub-micrometer-level values after the device is released. This approach overcomes the limitations of deep etching. Sub-100 nm capacitive transduction gaps are obtained, and the equivalent impedance of the resonator is significantly reduced.