Oriented Single-Crystal LiTaO3 Thin Film on Silicon for High Performances SAW Components

This paper investigates advanced piezoelectric-on-insulator (POI) substrates elaborated using the Smart Cut™ technology to transfer a thin, high uniformity, single-crystal LiTaO
₃
layer on top of a silicon handle wafer. These POI substrates enable the development of high quality surface acoustic wave (SAW) devices. Single-port test resonator have been built on such wafers, reaching Bode Q in excess of 1700 and coupling factors above 8 %, as the result of guided mode propagation. Resonance frequency dispersion was measured as low as 0.64 %. The thin layer stack also improves TCF down to 5.8 ppm/°C compared with conventional bulk LiTaO
₃
technology and can be further reduced at desired frequencies by optimizing the multi-layer stack thicknesses.