| abstract |
The present invention provides a piezoelectric thin film resonator and a filter having excellent mechanical strength, mountability, reliability, and productivity, and good piezoelectric film orientation, and a method of manufacturing the same. The space | gap 42 which has a dome-shaped expansion part is formed between the lower side of the lower electrode 43 of the area | region (membrane part 46) which the upper electrode 45 and the lower electrode 43 oppose, and the board | substrate 41. FIG. It is. And this space | gap 42 has the outline which the projection shape on the board | substrate 41 surface consists of a closed curve. The substrate 41 is also provided with an etching solution introduction hole 47 for etching the sacrificial layer used to etch the sacrificial layer to form the voids 42. The etching of the sacrificial layer 48 is performed so that the stress of the laminate (composite film) composed of the lower electrode 43, the piezoelectric film 44, and the upper electrode 45 becomes a compressive stress, and the composite film swells up to lower the electrode. A dome-shaped cavity 42 can be formed between the 43 and the substrate 41.n n n n Void, upper electrode, sacrificial layer, lower electrode, piezoelectric film, introduction hole |