| 摘要 |
PROBLEM TO BE SOLVED: To provide a bulk acoustic resonator which is packaged with high density onto a circuit board. SOLUTION: An acoustic resonator 1 is provided with: a substrate 3; a first acoustic reflection layer 5 disposed on the substrate 3; a resonance part 13 constituted by laminating a lower electrode layer 7, a piezoelectric layer 9 and an upper electrode layer 11 on the first acoustic reflection layer 5 in this order; a second acoustic reflection layer 15 laminated on the first acoustic reflection layer 5 while covering the resonance part 13; a plug 21 filling a connection hole 19 provided through the second acoustic reflection layer 15 and the piezoelectric layer 9 so as to reach the lower electrode layer 7; and a projecting electrode 23 provided on the side of the second acoustic reflection layer 15 with the plug 21 as its bottom face. Above the first acoustic reflection layer 5, a flattened insulating film 14 is provided to expose a shift electrode 11a on the upper electrode layer 11 via the piezoelectric layer 9. COPYRIGHT: (C)2004,JPO&NCIPI
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