Surface acoustic wave filter with a cap layer for improved reliability
US9973169B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 2015 |
| Grant date | May 15, 2018 |
| Priority date | — |
| Expiry date | Mar 25, 2036 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/131
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Embodiments of a Surface Acoustic Wave (SAW) device, or filter, and methods of fabrication thereof are disclosed. In some embodiments, the SAW filter comprises a piezoelectric substrate and an Interdigitated Transducer (IDT) on a surface of the piezoelectric substrate. The IDT includes multiple fingers, each comprising a metal stack. The SAW filter further includes a cap layer on a surface of the IDT opposite the piezoelectric substrate and on areas of the surface of the piezoelectric substrate exposed by the IDT. The cap layer has a thickness in a range of and including 10 to 500 Angstroms and a high electrical resistivity (and thus a low electrical conductivity). For instance, in some embodiments, the electrical resistivity of the cap layer is greater than 10 kilo-ohm meters (KΩ·m). The SAW filter further includes an oxide overcoat layer on a surface of the cap layer opposite the IDT and the piezoelectric substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.