BULK ACOUSTIC RESONATOR HAVING DOPED PIEZOELECTRIC LAYER

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PROBLEM TO BE SOLVED : To provide a bulk acoustic resonator having a large quality factor. SOLUTION : A piezoelectric thin film resonator (FBAR)100 includes, on a substrate 105 having an acoustic reflector 106 with a cavity, a first electrode 101 having a first electrode thickness, a second electrode 107 having a second electrode thickness, and an acoustic stack 110 formed of a piezoelectric layer 108 having a piezoelectric layer thickness, and arranged between the first electrode and second electrode. The piezoelectric layer is composed of a piezoelectric material doped with at least one rear earth element. For the specific acoustic coupling coefficient kt2 and series resonance frequency Fs of a bulk acoustic resonator, the first electrode thickness and second electrode thickness are larger than the thickness of the first electrode and second electrode of the bulk acoustic resonator including an undoped piezoelectric layer. COPYRIGHT : (C)2015, JPO&INPIT