Reduction of Transverse Leakage for SAW Resonators on LiTaO3 substrate

This paper proposes a new structure to reduce the transverse SAW leakage for the SAW resonator on a 42 degrees YX-LiTaO3 substrate. The leakage occurs from the inter-digital region toward the bus-bur region in the SAW resonators. The new structure has the Ta2O5 film on the outside of the inter-digital region. In this structure, the SAW velocity in the bus-bur region becomes slower than the velocity in the inter-digital region. Therefore, the new structure could reduce the leakage, and contribute to confine the SAW energy in the inter-digital region. This structure is applied to the SAW resonator and the Ladder-type SAW filter fabricated on a 42 degrees YX-LiTaO3 substrate. The insertion loss could be improved by reducing the transverse SAW leakage. This technique could be applied to the filters and duplexers using the leaky SAW on 42 degrees YX-LiTaO3 substrate, and the SAW devices could exhibit the excellent performances.