ABSTRACT A highly sensitive piezoelectric ultrasonic micro-sensor with a grooved multilayer membrane was developed by a Si-based MEMS technique. The groove was located at one-quarter of the distance away from the edge of the membrane and opened into piezoelectric layer. The piezoelectric layer Pb(Zr,Ti)O3 (PZT) was 2.2 μm thick and was prepared by a sol-gel method. The prepared PZT film was pure perovskite and showed a highly (100) textured structure. The sensitivity of the fabricated piezoelectric ultrasonic sensor without the groove structure was 100 μV/Pa. In comparison, the sensitivity of the ultrasonic sensor with the groove structure was about 500 μV/Pa, which is 5 times that without the groove structure. The diaphragm having grooves showed a corrugate-like structure that was formed by residual stress. The high sensitivity of the membrane with the grooved diaphragm is considered to relate to the corrugate-like structure.
Digital Object Identifier 10.1109/TUFFC.2007.557
© 2007, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.