Patent ID: 7235915
Filing Date: 2007-06-26
Classification: H03H

Abstract:
1. An acoustic resonator device, comprising: a substrate; and plural acoustic resonators that are formed on the substrate and have upper electrode layers, piezoelectric layers, and lower electrode layers, wherein all or part of the plural acoustic resonators resonate in resonance modes different from each other and at resonant frequencies corresponding to the resonance modes, and materials and thicknesses of the piezoelectric layers are common and substantially equal, the plural acoustic resonators are: a first acoustic resonator that has a first upper electrode layer, a first piezoelectric layer, and a first lower electrode layer and resonates in a λ/4 mode and at a first resonant frequency; and the first acoustic resonator has a first acoustic mirror that is provided between the first lower electrode layer and the substrate and has a structure in which first plural acoustic impedance layers are deposited, all the first plural acoustic impedance layers have a thickness substantially a quarter wavelength of the first resonant frequency, and among the first plural acoustic impedance layers, an acoustic impedance layer of an uppermost layer adjacent to the first lower electrode layer has an impedance higher than that of an acoustic impedance layer adjacent to an opposite side of the first lower electrode layer, a second acoustic resonator that is formed on the substrate, has a second upper electrode layer, a second piezoelectric layer, and a second lower electrode layer, and resonates in a λ/2 mode and at a second resonant frequency different from the first frequency, the second acoustic resonator has a second acoustic mirror having a same structure as the first acoustic mirror between the second lower electrode layer and the substrate, and a cavity is provided under the second lower electrode layer of the second acoustic mirror.