| 摘要 |
A film bulk acoustic wave resonator including a piezoelectric body 1 , and a first electrode 2 and a second electrode 3 that are provided respectively on the main surfaces of the piezoelectric body, the piezoelectric body being applied an electric field through the first and the second electrodes so as to generate a resonant vibration. A first mass load material portion 4 having an annular shape is provided outside the planar region of the first electrode on the main surface of the piezoelectric body, a mass load effect thereof being larger than that of the first electrode. The outer periphery of the first electrode and the inner periphery of the first mass load material portion are spaced apart from each other, whereby the first electrode and the first mass load material portion are electrically insulated from each other. The first mass load material portion has a laminated structure including a first auxiliary electrode layer 2 a and a load material layer 4 a formed on the auxiliary electrode layer. The first auxiliary electrode is formed with the same material to have the same thickness as the first electrode. Energy loss can be reduced, while the first mass load material portion can be formed easily with high precision.
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