Method for controlling piezoelectric coupling coefficient in film bulk acoustic resonators and apparatus embodying the method
US6954121B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 2003 |
| Grant date | Oct 11, 2005 |
| Priority date | — |
| Expiry date | Sep 16, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/02149
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An apparatus such as a thin film resonator has a bottom electrode, a top electrode, and a composite layer between the two electrodes. The composite layer includes a piezoelectric (PZ) layer having a first coupling coefficient and a coupling coefficient control (CCC) layer having a second coupling coefficient. By varying the relative thicknesses of the PZ layer and the CCC layer during the manufacturing process, the coupling coefficient of the resonator can be established (to any value between the first coupling coefficient and the second coupling coefficient) with minimal impact on resonant frequency. Further, it is relatively less difficult to fabricate the PZ layer and the CCC layer having the desired coupling coefficient (as a combination of the first coupling coefficient and the second coupling coefficient) compared to the difficulties of fabrication of a uniform PZ layer having the desired coupling coefficient.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.