Evolution of SAW and BAW Devices Using Thin LiTaO3 and LiNbO3

This paper reviews three types of HAL (Hetero Acoustic Layer) devices using thin LiTaO
3
(LT) and LiNbO
3
(LN). The production technology of thin LN and LT on a support wafer is a game-changing technology for acoustic wave devices, which has been made common by Murata Manufacturing's innovative work, “I.H.P. SAW.” We have started the development of HAL devices in 2013. LT/quartz HAL SAW devices demonstrated promising performances including high impedance ratio, near-zero TCF (temperature coefficient of frequency) and spurious-free high frequency characteristic. LN/quartz HAL SAW devices with an extremely high impedance ratio and ultrawide band were also demonstrated. Thin LT and LN are also useful for BAW devices. In this paper, we introduce an overtone SMR (solidly-mounted resonator) using LN on a unique Bragg reflector. The main response is at 9.5 GHz although
$1\ \mu\mathrm{m}$
thick LN is used. Finally, new types of BAW devices inspired by “XBAR” is briefly discussed.