Bulk acoustic wave resonator with reduced energy loss

• US 20090267457A1
• Filed: 04/24/2008
• Published: 10/29/2009
• Est. Priority Date: 04/24/2008
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Barber, Bradley P., Carpenter, Craig E., Bi, Frank
• Granted Patent: US 7,795,781 B2
• Time in Patent Office: Days
• US Class Current: 310/334
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/0542 consisting of a lateral arrangement H03H9/0566 takes precedence
• CPC Class Codes: H03H 9/17 having a single resonator crystal tuning forks H03H9/21
• 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
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

According to an exemplary embodiment, a bulk acoustic wave (BAW) resonator includes a piezoelectric layer having a disrupted texture region, where the disrupted texture region is situated in a controlled thickness region of the BAW resonator. The BAW resonator further includes lower and upper electrodes situated on opposite surfaces of the piezoelectric layer. The controlled thickness region has controlled electromechanical coupling and includes a segment of material situated over the upper electrode. The segment of material can be a metal or a dielectric material. The disrupted texture region can be situated at an edge of the BAW resonator and can extend along a perimeter of the BAW resonator.

Claims

1. A bulk acoustic wave (BAW) resonator comprising:

a piezoelectric layer having a disrupted texture region, said disrupted texture region being situated in a controlled thickness region of said BAW resonator;

lower and upper electrodes situated on opposite surfaces of said piezoelectric layer;

wherein said controlled thickness region has a controlled electromechanical coupling.

2. The BAW resonator of claim 1, wherein said controlled thickness region provides reduced electromechanical coupling into lateral modes.

3. The BAW resonator of claim 1, wherein said controlled thickness region is situated at an edge of said BAW resonator and extends along a perimeter of said BAW resonator.

4. The BAW resonator of claim 1, wherein said controlled thickness region includes a segment of material situated over said upper electrode.

5. The BAW resonator of claim 4, wherein said segment of material is selected from the group consisting of a metal and a dielectric material.

6. The BAW resonator of claim 1 further comprising a thin layer of silicon oxide underlying said disrupted texture region and situated between said lower electrode and said piezoelectric layer.

7. The BAW resonator of claim 1, wherein said disrupted texture region is situated at an edge of said BAW resonator and extends along a perimeter of said BAW resonator.

8. The BAW resonator of claim 4, wherein an outer edge of said segment of material is self-aligned with an edge of said upper electrode.

9. A method of forming a BAW resonator, said method comprising:

forming a lower electrode of said BAW resonator;

forming a piezoelectric layer over said lower electrode, said piezoelectric layer comprising a disrupted texture region, said disrupted texture region being situated in a controlled thickness region of said BAW resonator;

forming an upper electrode of said BAW resonator over said piezoelectric layer;

wherein said controlled thickness region has a controlled electromechanical coupling.

10. The method of claim 9, wherein said controlled thickness region provides reduced electromechanical coupling into lateral modes.

11. The method of claim 9, wherein said controlled thickness region is situated at an edge of said BAW resonator and extends along a perimeter of said BAW resonator.

12. The method of claim 9 further comprising forming a segment of material over said upper electrode.

13. The method of claim 12, wherein said segment of material is selected from the group consisting of a metal and a dielectric material.

14. The method of claim 9 further comprising forming a thin layer of silicon oxide over a region of said lower electrode over which said disrupted texture region is to be formed prior to forming said piezoelectric layer.

15. The method of claim 9 further comprising roughening a region of said lower electrode over which said disrupted texture region is to be formed prior to forming said piezoelectric layer.

16. A semiconductor die comprising at least one BAW resonator, said at least one BAW resonator comprising:

a piezoelectric layer having a disrupted texture region, said disrupted texture region situated in a controlled thickness region of said BAW resonator;

lower and upper electrodes situated on opposite surfaces of said piezoelectric layer;

wherein said controlled thickness region has a controlled electromechanical coupling.

17. The semiconductor die of claim 16, wherein said controlled thickness region provides reduced electromechanical coupling into lateral modes.

18. The semiconductor die of claim 16, wherein said controlled thickness region is situated at an edge of said BAW resonator and extends along a perimeter of said BAW resonator.

19. The semiconductor die of claim 16, wherein said controlled thickness region includes a segment of material situated over said upper electrode.

20. The semiconductor die of claim 16, wherein said semiconductor die is utilized in a circuit board as a part of an electronic system, said electronic system being selected from the group consisting of a wired or wireless communications device, a cell phone, a switching device, a router, a repeater, a codec, a wired or wireless LAN, a WLAN, a Bluetooth enabled device, a Global Positioning System (GPS) device, a computer, a monitor, a television set, a satellite set top box, a cable modem, a printer, a copier, an RF transceiver, and a personal digital assistant (PDA).