A low loss flexural plate wave (FPW) device through enhanced properties of sol–gel PZT (52/48) thin film and stable TiN-Pt bottom electrode

This paper presents the development of a robust process for the fabrication of a low loss FPW device. The transmission loss in the FPW is minimized by enhancing the texture and morphology of sol–gel PZT film through optimized pyrolysis and annealing processes. Reduction of lead loss in PZT coupled with the use of a new bottom electrode stack layer of Pt/TiN/Ti resulted in an eight-fold increase in the perovskite (1 1 1) phase, increasing the remanent polarization to 95.7 μC/cm2 and coercive field to 56.7 kV/cm. This represents 50% improvement in remanent polarization over the previously reported values for this sol–gel PZT. The FPW device was tested by driving the input Inter Digitated Transducers/Electrodes (IDTs) pair differentially out of phase by 180°. A transmission loss of 15 dBm was observed for an IDT design of 160 μm periodicity.