Thin plate longitudinal vibrator touch probe sensor using PZT thin film

Using PZT thin film, a vibro touch sensor was fabricated. The sensor is for measurement of material surface roughness and surface structure of micro devices such as VLSI up to subnanometer order resolution without any damages to work piece. The sensor element has flat shape. Base material was titanium thin plate whose thickness was 100 μm. On both sides of the titanium, PZT film was deposited 10 μm. The sensor element had half wave length longitudinal vibration mode. The resonance frequency of the sensor was about 304 kHz. The sensitivity of the device is the tangential of the pickup voltage decrease. In the experiment, the tangential was 0.018 mV/nm. From the sensitivity and the noise level, the resolution of the sensor was 2.4 nm.