Piezoelectric Actuator Integrated Cantilever with Tunable Spring Constant For Atom Probe

A scanning probe for time-of-flight scanning force microscopy (TOF-SFM) with Pb(Zr, Ti)O3(PZT) thin film actuators is designed and fabricated. This probe is designed to pick up an atom or molecule under SFM mode, and emits them to a TOF mass analyzer using field-assisted evaporation for analyzing its mass (AP; atom probe). For this operation, the probe should be actuated with a large displacement in order to exactly place the end of probe at the front of an extra electrode. The small spring constant of the probe is advantageous for obtaining large actuation, but the instability is caused during surface imaging due to pull-in. Therefore, a tuning actuator, which varies the stiffness ofthe probe with its active deformation, is integrated. The probe is fabricated using Si micromachining from a SOI wafer on which the PZT is deposited by sputtering. The fabricated probe generates a static displacement up to 15 pm with an applied voltage of 5V, also tuning of the spring constant is demonstrated.