Micromechanical resonators with sub-micron capacitive gaps in 2 µm process

An innovative gap reduction technique is reported to achieve sub-micron capacitive gaps for micromechanical resonators to boost the output signal using the standard low-cost 2 µm commercially available foundry process from MEMSCAP. Electrostatic actuation was used to reduce the gap size below the fabrication limitation. To demonstrate the proposed idea, a 6.35 MHz Lamé-mode square resonator was designed, fabricated and tested. The resonator gap size was experimentally measured to be 0.64 µm, which boosted the resonance peak by 20 dB.