| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a sound resonator which is robust and has a large Q value. SOLUTION: A filter is formed by using acoustic resonators (42, 62, 92). Each resonator has its own cavities (48, 76) and bottom electrodes (46, 64) spanning the cavities, and thus the bottom electrodes (44, 64) have unsupported internal areas surrounded by supported peripheral areas. In a preferable embodiment, the cavities are formed by forming depressions in substrates (46, 78) by etching, filling the depressions with a sacrificial material (52), deposting a conductive layer and an electrode layers (54 and 94) defining FBAR or SBAR, and then removing the sacrificial material from the depressions. Or the sacrificial material is removed through a release hole (60) limited to the periphery of the depressions. Preferably, the bottom electrode is the only electrode spanning the cavity, and consequently the formation of parasitic FBAR or parasitic SBAR is limited. |
