Abstract: This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film. The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/Al/LTO/Si₃N₄/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A₀ and symmetric S₀ modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application.

Key words: Lamb wave, MEMS, ZnO film, composite plate