A MEMS Lamb wave microdevice based on ZnO thin film

MEMS Lamb wave ultrasonic devices have been shown to be extremely useful for applications of sensor, actuator, resonator, and so on. This paper presents the design and fabrication of Lamb wave microdevice based on ZnO piezoelectric film. The Lamb waves were respectively launched and received by both Al interdigital transducers deposited on ZnO/Al/LTO/Si₃N₄/Si thin piezoelectric composite plate. The detail fabrication procedure of microdevice and characteristics of the ZnO film were presented. A novel method to obtain the piezoelectric constant of the ZnO film was used in this paper. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave microdevice indicated the measured center frequency of antisymmetric A₀ and symmetric S₀ modes Lamb wave agree with the theoretical predictions.