Film bulk acoustic wave resonator and manufacturing method thereof

• US 20070013463A1
• Filed: 04/03/2006
• Published: 01/18/2007
• Est. Priority Date: 07/18/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ha, Byeoung-ju, Song, In-sang, Park, Yun-kwon, Kim, Duck-hwan, Sul, Sang-chul, Kim, Chul-soo
• Granted Patent: US 7,423,501 B2
• Time in Patent Office: Days
• US Class Current: 333/187
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/02015 Characteristics of piezoelectric layers, e.g. cutting angles
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume

Abstract

A film bulk acoustic resonator includes a substrate; a lower electrode formed on top of the substrate; a piezoelectric membrane formed on top of the lower electrode and having a crystallographic axis so inclined as to generate a total reflection when an acoustic wave advances toward the lower electrode; and an upper electrode formed on top of the piezoelectric membrane.

Claims

1. A film bulk acoustic resonator comprising:

a substrate;

a lower electrode formed on top of the substrate;

a piezoelectric membrane formed on top of the lower electrode and having a crystallographic axis so inclined as to generate a total reflection when an acoustic wave advances toward the lower electrode; and

an upper electrode formed on top of the piezoelectric membrane.

2. The resonator as defined in claim 1, wherein the piezoelectric membrane is formed with a dense medium while the lower electrode is formed with a sparse medium.

3. The resonator as defined in claim 1, wherein the circumference of the piezoelectric membrane further comprises an enveloping wall.

8. The resonator as defined in claim 3, wherein the enveloping wall prevents the acoustic wave from being lost toward the lateral surfaces of the piezoelectric membrane.

9. The resonator as defined in claim 3, wherein the enveloping wall connects to the lower electrode.

10. The resonator as defined in claim 3, wherein the piezoelectric member has a smaller region that the lower electrode.

11. The resonator as defined in claim 10, wherein the enveloping wall is on top of the lower electrode protruding outside of the piezoelectric membrane and on the lateral surfaces of the piezoelectric membrane.

4. A manufacturing method of film bulk acoustic resonator comprising the steps of:

forming a lower electrode on top of a substrate;

forming a piezoelectric membrane on top of the lower electrode and having a crystallographic axis so inclined as to generate a total reflection when an acoustic wave advances toward the lower electrode; and

forming an upper electrode on top of the piezoelectric membrane.

5. The method as defined in claim 4 further comprising a step of forming an enveloping wall encompassing the circumference of the piezoelectric membrane.

6. The method as defined in claim 5, wherein the enveloping wall is vapor-deposited and patterned on the same layer as that of forming the upper electrode.

7. The method as defined in claim 4, wherein the piezoelectric membrane is vapor-deposited using the sputtering or the evaporation method.

12. The method as defined in claim 5, wherein the enveloping wall is formed to connect to the lower electrode.

13. The method as defined in claim 5, wherein the piezoelectric member is formed to have a smaller region that that of the lower electrode.

14. The method as defined in claim 13, wherein the enveloping wall is simultaneously deposited on top of the lower electrode protruding outside of the piezoelectric membrane and on the lateral surfaces of the piezoelectric membrane.