| 摘要 |
PURPOSE: A piezoelectric resonator, a filter, and an electronic communication device are provided to reduce the loss of resonance energy on electrodes and significantly improve the stability of resonance frequency to the change of temperature. CONSTITUTION: A piezoelectric resonator(1) is preferably a thickness-longitudinal vibration type resonator, and includes a substrate(2), a diaphragm(3), and a vibration unit(4). The substrate(2) is preferably made of Si and has a hole(5) passing through the substrate(2) from the front surface to the rear surface. The diaphragm(3) functions as an external thin-film portion and is preferably made of a SiO2 thin-film. The diaphragm(3) is arranged so as to cover the hole(5). The vibration unit(4) is located on the diaphragm(3), and includes a pair of upper and lower electrodes(4b,4a), and an internal thin-film portion(4c) having one or more layers. The internal thin-film portion(4c) includes at least a piezoelectric film that is interposed between the upper and lower electrode.
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