PIEZOELECTRIC THIN FILM RESONATOR, FILTER AND MULTIPLEXER

To provide a piezoelectric thin film resonator in which damage to a piezoelectric film can be suppressed.SOLUTION: A piezoelectric thin film resonator 100 includes: a substrate 10; a support layer 18 provided on the substrate 10; a lower electrode 12 provided on the support layer 18; a piezoelectric film 14 which is provided on the lower electrode 12 and which has a first coefficient of linear expansion, the absolute value of a difference between the first coefficient of linear expansion and a third coefficient of linear expansion of the support layer 18 being smaller than the absolute value of a difference between the first coefficient of linear expansion and a second coefficient of linear expansion of the substrate 10; and an upper electrode 16 which is provided on the piezoelectric film 14 and which overlaps, in plan view, the lower electrode 12 and a gap 30 formed between the substrate 10 and the lower electrode 12.SELECTED DRAWING: Figure 1 【課題】圧電膜の破損が抑制された圧電薄膜共振器を提供する。【解決手段】圧電薄膜共振器１００は、基板１０と、基板１０上に設けられた支持層１８と、支持層１８上に設けられた下部電極１２と、下部電極１２上に設けられ、第１線膨張係数を有し、第１線膨張係数と基板１０の第２線膨張係数との差の絶対値よりも第１線膨張係数と支持層１８の第３線膨張係数との差の絶対値が小さい圧電膜１４と、圧電膜１４上に設けられ、基板１０と下部電極１２との間に形成された空隙３０および下部電極１２に平面視において重なる上部電極１６とを備える。【選択図】図１