Piezoelectric resonator structures having temperature compensation

• US 20100327701A1
• Filed: 06/30/2009
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies Wireless IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Grannen, Kevin J., Rogers, Carrie A., Choy, John
• Granted Patent: US 9,209,776 B2
• Time in Patent Office: Days
• US Class Current: 310/346
• CPC Class Codes: H03H 2003/021 the resonators or networks being of the air-gap type
• CPC Class Codes: H03H 2003/0407 Temperature coefficient
• CPC Class Codes: H03H 2003/0442 of a non-piezoelectric layer
• CPC Class Codes: H03H 3/04 for obtaining desired frequency or temperature coefficient
• CPC Class Codes: H03H 9/02102 of temperature influence cutting angles H03H9/02015
• CPC Class Codes: H03H 9/173 Air-gaps
• CPC Class Codes: H03H 9/583 comprising a plurality of piezoelectric layers acoustically coupled
• CPC Class Codes: H03H 9/587 Air-gaps
• CPC Class Codes: H10N 30/85 Piezoelectric or electrostrictive active materials
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

An electrical resonator comprises a substrate comprising a cavity. The electrical resonator comprises a resonator stack suspended over the cavity. The resonator stack comprises a first electrode; a second electrode; a piezoelectric layer; and a temperature compensating layer comprising borosilicate glass (BSG).

Claims

1. An electrical resonator, comprising:

a substrate;

a cavity in the substrate; and

a resonator stack suspended over the cavity and comprising;

a first electrode;

a second electrode;

a piezoelectric layer; and

a temperature compensating layer comprising borosilicate glass (BSG).

2. An electronic resonator as claimed in claim 1, wherein the temperature compensation layer is disposed between the first electrode and the piezoelectric layer.

3. An electronic resonator as claimed in claim 1, wherein the temperature compensation layer is disposed between the second electrode and the piezoelectric layer.

4. An electronic resonator as claimed in claim 1, wherein the temperature compensation layer is disposed over the substrate and beneath the first electrode.

5. An electronic resonator as claimed in claim 1, wherein the temperature compensation layer is disposed over the second electrode.

6. An electronic resonator as claimed in claim 1, further comprising a second resonator stack disposed over the first resonator stack, the second resonator stack comprising:

a third electrode;

a fourth electrode;

a second piezoelectric layer; and

a second temperature compensating layer comprising borosilicate glass (BSG).

7. An electronic resonator as claimed in claim 1, wherein the temperature compensation layer is disposed between the first electrode and the piezoelectric layer.

8. An electronic resonator as claimed in claim 1, wherein the second temperature compensation layer is disposed between the fourth electrode and the second piezoelectric layer.

9. An electronic resonator as claimed in claim 1, wherein the second temperature compensation layer is disposed over the second electrode and beneath the third electrode.

10. An electronic resonator as claimed in claim 1, wherein the second temperature compensation layer is disposed over the fourth electrode.

11. A method of fabricating an electrical resonator, the method comprising:

forming a cavity in a substrate;

providing a layer of sacrificial material in the cavity;

forming a resonator stack over the cavity, the forming of the resonator stack comprising forming a temperature compensation layer comprising borosilicate glass (BSG); and

removing the sacrificial material from the cavity.

12. A method of fabricating an electrical resonator as claimed in claim 11, wherein the forming the temperature compensation layer comprises combining silicon dioxide and boron combined dynamically in a vacuum.

13. A method as claimed in claim 11, wherein the forming the temperature compensation layer comprises forming a mixture of silicon dioxide and boron, and depositing the mixture in a vacuum.

14. A method as claimed in claim 11, wherein a concentration of boron in the BSG layer is in the range of approximately 0.1% to approximately 5.0% atomic mass percentage or weight percentage.

15. A method as claimed in claim 11, further comprising patterning the temperature compensation layer within a boundary of the first electrode or substantially coincident with the boundary.