High quality factor silicon cantilever driven by piezoelectric thin film actuator for resonant based mass detection

A high quality factor (Q-factor) piezoelectric lead zirconate titanate (PZT) thin film actuated single crystal silicon cantilever was proposed in this paper for resonant based ultra sensitive mass detection. Intrinsic energy dissipation and other negative effects from PZT-electrode stack were successfully compressed by separating the PZT actuator from the resonant structure. Excellent Q-factor, which is comparable to silicon cantilever (without actuator) and several times larger than that of latest reported other integrated cantilevers, was successfully obtained under both atmospheric pressure and reduced pressures. For a 30 μm-wide 100 μm-long cantilever, the Q-factor was measured as 1,113 and 7,279 under the pressure of 101.2 KPa and 35 Pa, respectively. Besides, it was found that greater Q-factor can be achieved at high vibration mode by the proposed structure. However, support loss became significant because of the increased actuator's vibration amplitude which in turn leads to unexpected energy dissipation. Therefore, an optimized structure using node-point actuation was suggested and discussed in last section of this paper.