ELASTIC WAVE DEVICE, FILTER, MULTIPLEXER, WAFER, AND METHOD OF MANUFACTURING WAFER

To provide an elastic wave device capable of improving the bonding strength between an interlayer and a piezoelectric substrate.SOLUTION: An elastic wave device comprises: a support substrate 10; a first interlayer 12 provided on the support substrate 10 and having average grain diameter of crystal grains of 100 nm or more; a second interlayer 13 provided on the first interlayer 12, where roughness of an interface 32 with the first interlayer 12 is smaller than that of an interface between the support substrate 10 and the first interlayer 12, the second interlayer being thinner than the first interlayer 12, and having average grain diameter of crystal grains of less than 100 nm; a piezoelectric substrate 14 directly bonded onto the second interlayer 13; and a pair of comb-shaped electrodes 20 provided on the piezoelectric substrate 14.SELECTED DRAWING: Figure 1 【課題】中間層と圧電基板と接合強度を向上させ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、結晶粒の平均粒径が１００ｎｍ以上である第１中間層１２と、第１中間層１２上に設けられ、第１中間層１２との界面３２の粗さは支持基板１０と第１中間層１２との界面の粗さより小さく、第１中間層１２より薄く、結晶粒の平均粒径が１００ｎｍ未満である第２中間層１３と、第２中間層１３上に直接接合された圧電基板１４と、圧電基板１４上に設けられた一対の櫛型電極２０とを備える。【選択図】図１