Patent · US Expired

Bulk acoustic wave filter with a roughened substrate bottom surface and method of fabricating same

US6943647B2 · kind B2 · utility

30Cited by

9References

20Claims

0Family size

Assignees

Infineon Technologies AG · DE
Nokia · FI

Inventors

Robert Aigner · Winter Garden, US
Pasi Tikka · Munich, DE
Juha Ellä · Halikko, FI

Key dates

Filing date	May 6, 2004
Grant date	Sep 13, 2005
Priority date	—
Expiry date	May 6, 2024

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10T29/42
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

A filter device comprises a substrate having a top surface and a bottom surface, and at least one acoustic wave situated on the top surface of the substrate, wherein the bottom surface of the substrate is roughened to reduce the reflection of an acoustic wave back to the acoustic wave filter. The effect achieved by the roughening of the bottom surface of the substrate that an acoustic wave which is generated by the acoustic wave filter and reaches the bottom surface of the substrate, is basically scattered so the acoustic wave that is actually reflected back to the acoustic wave device is reduced which, in turn, improves the performance characteristics of the acoustic wave filter.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.