BORDER RING MODE SUPPRESSION IN SOLIDLY-MOUNTED BULK ACOUSTIC WAVE RESONATOR

• US 20140273881A1
• Filed: 03/12/2013
• Published: 09/18/2014
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: TriQuint Semiconductor Incorporated (Qorvo, Inc.)
• Inventors: Tajic, Alireza
• Granted Patent: US 9,450,565 B2
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/131 consisting of a multilayered structure
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/175 Acoustic mirrors
• CPC Class Codes: H03H 9/589 Acoustic mirrors
• CPC Class Codes: H03H 9/703 Networks using bulk acoustic wave devices
• CPC Class Codes: H03H 9/706 Duplexers
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

Embodiments provide a solidly-mounted bulk acoustic wave (BAW) resonator and method of making same. In embodiments, the BAW resonator may include one or more extensions that are acoustical similar to active region components of the BAW resonator. Other embodiments may be described and claimed.

Claims

1. A solidly-mounted bulk acoustic wave resonator comprising:

an internal region, a border region, and an external region;

a piezoelectric layer disposed in the internal region, the border region, and the external region;

a first electrode coupled with a first surface of the piezoelectric layer and disposed in the internal region and the border region;

an extension coupled with the first surface of the piezoelectric layer and disposed in the external region, the extension having an acoustic impedance that is at least similar to an acoustic impedance of the first electrode; and

a second electrode coupled with a second surface of the piezoelectric layer, the second surface being opposite the first surface.

2. The solidly-mounted BAW resonator of claim 1, wherein the first electrode is a top electrode and comprises aluminum copper and the extension comprises silicon oxide.

3. The solidly-mounted BAW resonator of claim 2, wherein the first electrode consists of aluminum copper.

4. The solidly-mounted BAW resonator of claim 1, wherein the first electrode is a top electrode and comprises molybdenum and the extension comprises hafnium oxide.

5. The solidly-mounted BAW resonator of claim 4, wherein the first electrode consists of molybdenum.

6. The solidly-mounted BAW resonator of claim 1, wherein the extension is a first extension, the first electrode is a top electrode, the second electrode is a bottom electrode, and the BAW resonator further comprises:

a second extension directly coupled with the second surface of the piezoelectric layer and disposed in the external region, the second extension having an acoustic impedance that is at least similar to an acoustic impedance of the second electrode.

7. The solidly-mounted BAW resonator or claim 6, wherein both the second extension and the second electrode include a tungsten layer and an aluminum copper layer.

8. The solidly-mounted BAW resonator of claim 7, wherein the top electrode comprises aluminum copper and has a thickness of approximately 200 nanometers, the tungsten layer has a thickness of approximately 70 nanometers, and the aluminum copper layer has a thickness of approximately 190 nanometers.

9. The solidly-mounted BAW resonator of claim 8, wherein a difference between an anti-resonance frequency of the external region and an anti-resonance frequency of the active region is approximately 57 megahertz.

10. The solidly-mounted BAW resonator of claim 8, wherein a difference between a resonance frequency of the border region and a resonance frequency of the active region is approximately 40 megahertz and a width of the border region is approximately 2.0 microns.

11. The solidly-mounted BAW resonator of claim 8, wherein the top electrode comprises molybdenum and has a thickness of approximately 215 nanometers, the piezoelectric layer has a thickness of approximately 1200 nanometers, the tungsten layer has a thickness of approximately 184 nanometers, and the aluminum copper layer has a thickness of approximately 100 nanometers.

12. The solidly-mounted BAW resonator of claim 11, wherein a difference between an anti-resonance frequency of the external region and an anti-resonance frequency of the active region is approximately 196 megahertz.

13. The solidly-mounted BAW resonator of claim 11, wherein a difference between a resonance frequency of the border region and a resonance frequency of the active region is approximately 40 megahertz and a width of the border region is approximately 2.0 microns.

14. The solidly-mounted BAW resonator of claim 8, wherein:

the top electrode comprises molybdenum and has a thickness of approximately 200 nanometers;

the piezoelectric layer has a thickness of approximately 1200 nanometers;

the tungsten layer has a thickness of approximately 170 nanometers;

the aluminum copper layer has a thickness of approximately 250 nanometers;

a difference between an anti-resonance frequency of the external region and an anti-resonance frequency of the active region is approximately 49 megahertz;

a difference between a resonance frequency of the border region and the resonance frequency of the active region is approximately 130 megahertz; and

a width of the border region is approximately 0.25 microns.

15. The solidly-mounted BAW resonator of claim 8, further comprising:

a reflector having a plurality of tungsten layers disposed in silicon oxide coupled with the piezoelectric layer.

17. The solidly-mounted BAW resonator of claim 1, further comprising:

a top electrode including the first electrode or the second electrode; and

a mass load coupled with the top electrode in the border region.

18. The solidly-mounted BAW resonator of claim 17, wherein the top electrode includes the first electrode and the mass load is further coupled with the extension in the external region.

16. The solidly-mounted BAW resonator, wherein the extension is a dielectric material.

19. A system comprising:

a transceiver to transmit and receive radio frequency signals;

a filter coupled with the transceiver and configured to filter RF signals provided to the transceiver;

a power amplifier coupled with the transceiver and configured to amplify RF signals received from the transceiver;

an antenna structure to transmit and receive RF signals over the air; and

an antenna switch module to selective couple the antenna structure with the filter and the power amplifier,

wherein the filter includes a bulk acoustic wave (BAW) resonator having;

first and second electrodes coupled with a piezoelectric material; and

an extension adjacent to the first electrode and having an acoustic impedance that is at least similar to an acoustic impedance of the first electrode.

20. The system of claim 19, wherein the first electrode is a top electrode that comprises aluminum copper and the extension comprises silicon dioxide.

21. The system of claim 19, wherein the first electrode is a top electrode that comprises molybdenum and the extension comprises hafnium dioxide.

22. The system of claim 19, wherein the first electrode is a bottom electrode that comprises an aluminum copper layer and a tungsten layer and the extension comprises an aluminum copper layer and a tungsten layer.

23. The system of claim 19, wherein the BAW resonator comprises an active region, a border region, and an external region, and the extension is disposed in the external region.

24. A method of manufacturing a bulk acoustic wave (BAW) resonator comprising:

forming a piezoelectric layer with a first surface and a second surface;

forming a first electrode at a first surface of the piezoelectric layer;

forming a second electrode at a second surface of the piezoelectric layer; and

forming an extension, that is acoustically similar to the first electrode, at the first surface adjacent to the first electrode.

25. The method of claim 24, further comprising:

forming the first electrode of aluminum copper and forming the extension of silicon dioxide.

26. The method of claim 24, further comprising:

forming the first electrode of molybdenum and forming the extension of hafnium oxide.

27. The method of claim 24, wherein the extension is a first extension and the method further comprises:

forming a second extension at the second surface of the piezoelectric layer adjacent the second electrode,

wherein the first and second extensions are in an external region of the BAW resonator.