Thermally actuated I-shaped electromechanical VHF resonators

Fabrication and characterization results are presented for the highest frequency (112-176 MHz) and smallest footprint (area: ~70 μm²) thermal-piezoresistive single crystal silicon (SCS) resonators yet reported. The devices in this work have similar I-shaped or dumbbell geometry as previous work but with considerably smaller dimensions. An SOIMEMS fabrication process was developed that employs electron beam lithography to achieve submicron dimensions. Strong performance (Q = 5750, g_m = 89.6 μA/V) is demonstrated, as is frequency tunability (up to 3.6% in vacuum) via DC bias current adjustment. Simple geometry and fabrication make these devices useful alternatives to capacitive and piezoelectric resonators.