Highly sensitive structures for ultrasonic microsensors by buckling control of diaphragms through intrinsic stress of PZT films

Highly sensitive structures for ultrasonic microsensors have been easily achieved by controlling buckling behavior of the sensor diaphragms through intrinsic stress of sol-gel derived piezoelectric lead-zirconate-titanate (PZT) films. Upward buckled diaphragms are necessary for the high sensitivity, and were previously fabricated through two-step PZT formation process to prevent the diaphragms from being flattened due to a strong tension caused by tensile stress of PZT. In this work a new preparation process has been used for a low stress PZT in order to simplify the fabrication process to one-step PZT formation, and has yielded twice as large buckling deflection as previous sensors on the upward buckled diaphragms.