Single and mechanically coupled capacitive silicon nanomechanical resonators

The design, fabrication and evaluation of single and mechanically coupled capacitive silicon nanomechanical resonators is reported. The structure of resonators is fabricated on a silicon on insulator wafer and transferred to a Tempax glass substrate by anodic bonding. A finite element method simulation has been conducted to investigate the vibration modes of the resonators. Single beam resonator with a length of 21.3 μm, a width of 500 nm, a thickness of 5 μm and the capacitive gap size of about 300 nm shows a nonlinear response. The amplitude of frequency response increases as the frequency is swept upward, and then suddenly jumps to a lower value. The mechanically coupled capacitive silicon nanomechanical resonator with a number of 100 individual beams above is successfully fabricated. Some resonant peaks can be observed, which shows that most nanomechanical resonators are mechanically coupled and synchronised. A mechanical resonance at a high frequency of ∼7.2 MHz in flexural mode has been detected. A small motional resistance of 1.2 kω has been achieved by the mechanical coupling.