ACOUSTIC WAVE DEVICE, FILTER AND MULTIPLEXER

To provide an acoustic wave device for suppressing spurious.SOLUTION: An acoustic wave device includes: a support substrate 10; a piezoelectric layer 14 formed on the support substrate 10; at least a pair of combed-shaped electrodes 20 formed on the piezoelectric layer 14 and including a plurality of electrode fingers 18 for exciting elastic waves; a temperature compensation film 13 formed between the support substrate 10 and the piezoelectric layer 14 and having a code of a temperature coefficient of an elastic constant which is against a code of a temperature coefficient of an elastic constant of the piezoelectric layer 14; a boundary layer 12 formed between the support substrate 10 and the temperature compensation film 13 and propagating a bulk wave whose acoustic velocity is higher than that of a bulk wave propagating through the temperature compensation film 13 and lower than that of a bulk wave propagating through the support substrate 10; and an intermediate layer 11 formed between the support substrate 10 and the boundary layer 12 and having a Q value lower than a Q value of the boundary layer 12.SELECTED DRAWING: Figure 1 【課題】スプリアスを抑制する弾性波デバイスを提供する。【解決手段】弾性波デバイスは、支持基板１０と、支持基板１０上に設けられる圧電層１４と、圧電層１４上に設けられ、弾性波を励振する複数の電極指１８を備える少なくとも一対の櫛歯状電極２０と、支持基板１０と圧電層１４との間に設けられ、圧電層１４の弾性定数の温度係数の符号とは弾性定数の温度係数の符号が反対である温度補償膜１３と、支持基板１０と温度補償膜１３との間に設けられ、温度補償膜１３を伝搬するバルク波の音速より速くかつ支持基板１０を伝搬するバルク波の音速より遅いバルク波が伝搬する境界層１２と、支持基板１０と境界層１２との間に設けられ、境界層１２のＱ値より低いＱ値を有する中間層１１とを備える。【選択図】図１