| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a thin-film acoustic resonator with reduced spurious excitation, improved characteristics and improved endurance. <P>SOLUTION: The thin-film acoustic resonator manufacturing method includes processes of forming: a sacrifice layer partially on a surface of a substrate 11, on a surface of the sacrifice layer a lower electrode layer 23 whose variation in an RMS of a surface height is less than 20 nm, a piezoelectric thin-film layer 22 and an upper electrode layer 21 on the lower electrode layer, and a cavity 12 in a lower portion of a sandwiching structure by penetrating at least one layer of the lower electrode layer constituting the sandwiching structure obtained in the former processes, the piezoelectric thin-film layer and the upper electrode layer to make a small hole reaching the surface of the sacrifice layer for etching by introducing an etching liquid from the small hole to remove the sacrifice layer. Thereby, obtained is the thin-film acoustic resonator with the sandwiching structure bridged over the cavity. <P>COPYRIGHT: (C)2007,JPO&INPIT |
