Thin film piezoelectric bulk acoustic wave resonator and radio frequency filter using the same
US7489063B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 2007 |
| Grant date | Feb 10, 2009 |
| Priority date | — |
| Expiry date | Jan 26, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H2003/0471
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An object of the present invention is to provide an inexpensive thin film piezoelectric bulk acoustic wave resonator that allows fine-tuning of a resonant frequency. Another object is to provide an inexpensive filter with dramatically improved frequency characteristics, using thin film piezoelectric bulk acoustic wave resonators that can be formed on one substrate. A thin film piezoelectric bulk acoustic wave resonator of the present invention has a laminated structure including a piezoelectric thin film, and a first metal electrode film and a second metal electrode film between which part of the piezoelectric thin film is sandwiched; the first metal electrode film has a plurality of holes formed on an electrode plane opposite to the second metal electrode film and having a depth equivalent to at least the thickness of the first metal electrode film; and if a combined thickness of top and bottom electrode layers and the piezoelectric thin film is ht, the covering ratio σ of the electrode plane of the first metal electrode film satisfies a condition 0<σ<1 for every 1.28 ht pitch.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.