Adjusted frequency temperature coefficient resonator

• US 20070063622A1
• Filed: 09/09/2005
• Published: 03/22/2007
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Avago Technologies Wireless IP Singapore Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Rudy, Richard
• Granted Patent: US 7,868,522 B2
• Time in Patent Office: Days
• US Class Current: 310/341
• 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 2003/0471 of a plurality of resonators at different frequencies
• 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 9/585 Stacked Crystal Filters [SCF]
• CPC Class Codes: H03H 9/587 Air-gaps

Abstract

A temperature compensated pair of resonators. The temperature compensated pair of resonators comprises a first resonator configured to resonate at a first frequency and having a first frequency temperature coefficient and a second resonator configured to resonate at a second frequency and having a second frequency temperature coefficient. The second frequency is greater than the first frequency; the second frequency temperature coefficient is less than the first frequency temperature coefficient; and the first and the second resonators are fabricated on a common substrate.

Claims

1. A temperature compensated pair of resonators, comprising:

a first resonator configured to resonate at a first frequency and having a first frequency temperature coefficient; and

a second resonator configured to resonate at a second frequency and having a second frequency temperature coefficient, wherein the second frequency is greater than the first frequency, wherein the second frequency temperature coefficient is less than the first frequency temperature coefficient, and wherein the first and the second resonators are fabricated on a common substrate.

2. The temperature compensated pair of resonators as recited in claim 1:

wherein the first resonator comprises,

a first bottom electrode overlaying part of the substrate;

a first piezoelectric structure overlaying at least part of the first bottom electrode; and

a first top electrode, wherein the first top electrode is located over at least part of the first piezoelectric structure; and

wherein the second resonator comprises,

a second bottom electrode overlaying part of the substrate;

a second piezoelectric structure overlaying at least part of the second bottom electrode; and

a second top electrode overlaying at least part of the second piezoelectric structure.

3. The temperature compensated pair of resonators as recited in claim 2, further comprising:

a mass load layer overlaying at least part of the first top electrode, wherein the first top electrode overlays at least part of the first piezoelectric structure.

4. The temperature compensated pair of resonators as recited in claim 2, further comprising:

a mass load layer overlaying at least part of the first piezoelectric structure, wherein the first top electrode overlays at least part of the mass load layer.

5. The temperature compensated pair of resonators as recited in claim 2,

wherein the first piezoelectric structure comprises:

a first bottom piezoelectric layer overlaying at least part of the first bottom electrode;

an interstitial layer overlaying at least part of the first bottom piezoelectric layer; and

a first top piezoelectric layer overlaying at least part of the interstitial layer; and

wherein the second piezoelectric structure comprises;

a second bottom piezoelectric layer overlaying at least part of the second bottom electrode; and

a second top piezoelectric layer overlaying at least part of the second bottom piezoelectric layer.

6. The temperature compensated pair of resonators as recited in claim 5, further comprising:

a mass load layer overlaying at least part of the first top electrode, wherein the first top electrode overlays at least part of the first piezoelectric structure.

7. The temperature compensated pair of resonators as recited in claim 5, further comprising:

a mass load layer overlaying at least part of the first piezoelectric structure, wherein the first top electrode overlays at least part of the mass load layer.

8. The temperature compensated pair of resonators as recited in claim 1,

wherein the first resonator comprises:

a first bottom electrode overlaying part of the substrate;

a first piezoelectric layer overlaying at least part of the first bottom electrode;

a first top electrode; and

a mass load layer, wherein the first top electrode overlays at least part of the first piezoelectric layer and the mass load layer overlays at least part of the first top electrode or wherein the mass load layer overlays at least part of the first piezoelectric layer and the first top electrode overlays at least part of the mass load layer; and

wherein the second resonator comprises;

a second bottom electrode overlaying part of the substrate;

a second piezoelectric layer overlaying at least part of the second bottom electrode; and

a second top electrode overlaying at least part of the second piezoelectric layer, wherein the temperature coefficient of the stiffness of the mass load layer differs from that of the second top electrode.

9. The temperature compensated pair of resonators as recited in claim 8, wherein the mass load layer is an organic material.

10. The temperature compensated pair of resonators as recited in claim 9, wherein the organic material is selected from the group consisting of PMMA (Polymethyl-methacrylate), PY (Polyimides), and BCB (Benzocyclobutene).

11. The temperature compensated pair of resonators as recited in claim 8, wherein the mass load layer is a resin.

12. The temperature compensated pair of resonators as recited in claim 11, wherein the resin is a low-k material.

13. The temperature compensated pair of resonators as recited in claim 8, wherein the mass load layer is an oxide.

14. The temperature compensated pair of resonators as recited in claim 1,

wherein the first resonator comprises:

a bottom mass load layer;

a first bottom electrode;

a first piezoelectric layer, wherein the bottom mass load layer overlays part of the substrate, the first bottom electrode overlays at least part of the first bottom mass load layer, and the first piezoelectric layer overlays at least part of the first bottom electrode or wherein the first bottom electrode overlays part of the substrate, the bottom mass load layer overlays at least part of the first bottom electrode, and the first piezoelectric layer overlays at least part of the bottom mass load layer; and

a first top electrode located over at least part of the first piezoelectric layer; and

wherein the second resonator comprises;

a second bottom electrode overlaying part of the substrate;

a second piezoelectric layer overlaying at least part of the second bottom electrode; and

a second top electrode overlaying at least part of the second piezoelectric layer, wherein the temperature coefficient of the stiffness of the bottom mass load layer differs from that of the second bottom electrode.

15. The temperature compensated pair of resonators as recited in claim 14, further comprising:

a mass load layer overlaying at least part of the first top electrode, wherein the first top electrode overlays at least part of the first piezoelectric structure.

16. The temperature compensated pair of resonators as recited in claim 14, further comprising:

a mass load layer overlaying at least part of the first piezoelectric structure, wherein the first top electrode overlays at least part of the mass load layer.

17. The temperature compensated pair of resonators as recited in claim 14, wherein the mass load layer is an organic material.

18. The temperature compensated pair of resonators as recited in claim 17, wherein the organic material is selected from the group consisting of PMMA (Polymethyl-methacrylate), PY (Polyimides), and BCB (Benzocyclobutene).

19. The temperature compensated pair of resonators as recited in claim 14, wherein the mass load layer is a resin.

20. The temperature compensated pair of resonators as recited in claim 19, wherein the resin is a low-k material.

21. The temperature compensated pair of resonators as recited in claim 14, wherein the mass load layer is an oxide.

22. A method for fabricating a first resonator and a second resonator on a substrate, comprising:

creating a first bottom electrode and a second bottom electrode, wherein the first bottom electrode and the second bottom electrode partially overlay the substrate;

creating a first bottom piezoelectric layer and a second bottom piezoelectric layer, wherein the first bottom piezoelectric layer at least partially overlays the first bottom electrode and wherein the second bottom piezoelectric layer at least partially overlays the second bottom electrode;

creating an interstitial layer, wherein the interstitial layer at least partially overlays the first bottom piezoelectric layer;

creating a first top piezoelectric layer and a second top piezoelectric layer, wherein the first top piezoelectric layer at least partially overlays the interstitial layer and wherein the second top piezoelectric layer at least partially overlays the second bottom piezoelectric layer; and

creating a first top electrode and a second top electrode, wherein the first top electrode is located over at least part of the first top piezoelectric layer and wherein the second top electrode at least partially overlays the second top piezoelectric layer.

23. The method as recited in claim 22, further comprising:

creating a mass load layer overlaying at least part of the first top electrode, wherein the first top electrode overlays at least part of the first piezoelectric structure.

24. The method as recited in claim 22, further comprising:

prior to the step creating a first top electrode and a second top electrode, creating a mass load layer overlaying at least part of the first piezoelectric structure, wherein the first top electrode overlays at least part of the mass load layer.

25. The method as recited in claim 22, further comprising:

removing a portion of the thickness of the first top electrode and a portion of the thickness of the second top electrode or removing a portion of the thickness of the second top electrode and a portion of the thickness of the mass load layer.

26. The method as recited in claim 22, further comprising:

removing a portion of the thickness of first top piezoelectric layer while maintaining the thickness of the second top piezoelectric layer or removing a portion of the thickness of second top piezoelectric layer while maintaining the thickness of the first top piezoelectric layer or removing a portion of the thickness of the first top electrode while maintaining the thickness of the second top electrode or removing a portion of the thickness of the second top electrode while maintaining the thickness of the first top electrode or removing a portion of the thickness of the mass load layer while maintaining the thickness of the second top electrode or removing a portion of the thickness the second top electrode while maintaining the thickness of the mass load layer.

27. The method as recited in claim 22, further comprising:

prior to creating the first bottom electrode and the second bottom electrode, creating a first cavity and a second cavity on a top surface of the substrate;

filling the first and the second cavities with a sacrificial material, wherein the first bottom electrode overlays part of the first cavity and a part of the substrate surrounding the first cavity and wherein the second bottom electrode overlays part of the second cavity and a part of the substrate surrounding the second cavity; and

subsequently, removing the sacrificial material.

28. The method as recited in claim 22, further comprising:

prior to creating the first bottom electrode and the second bottom electrode, creating a cavity on a top surface of the substrate;

filling the cavity with a sacrificial material, wherein the first bottom electrode and the second bottom electrode form a composite bottom electrode which overlays part of the cavity and part of the substrate surrounding the cavity; and

subsequently, removing the sacrificial material.

29. A method for fabricating a first resonator and a second resonator on a substrate, comprising:

creating a first bottom electrode partially overlaying the substrate and a second bottom electrode partially overlaying the substrate;

creating a first piezoelectric layer and a second piezoelectric layer, wherein the first piezoelectric layer at least partially overlays the first bottom electrode and wherein the second piezoelectric layer at least partially overlays the second bottom electrode;

creating a first top electrode and a second top electrode, wherein the second top electrode at least partially overlays the second piezoelectric layer; and

creating a mass load layer, wherein the temperature coefficient of the stiffness of the mass load layer differs from that of the second top electrode and wherein either the first top electrode at least partially overlays the first piezoelectric layer and the mass load layer at least partially overlays the first top electrode or the mass load layer at least partially overlays the first piezoelectric layer and the first top electrode at least partially overlays the mass load layer.

30. The method as recited in claim 29, wherein the mass load layer is an organic material.

31. The method as recited in claim 30, wherein the organic material is selected from the group consisting of PMMA (Polymethyl-methacrylate), PY (Polyimides), and BCB (Benzocyclobutene).

32. The method as recited in claim 29, wherein the mass load layer is a resin.

33. The method as recited in claim 32, wherein the resin is a low-k material.

34. The method as recited in claim 29, wherein the mass load layer is an oxide.

35. The method as recited in claim 29, further comprising:

removing a portion of the thickness of the first top electrode and a portion of the thickness of the second top electrode or removing a portion of the thickness of the second top electrode and a portion of the thickness of the mass load layer.

36. The method as recited in claim 29, further comprising:

removing a portion of the thickness of first piezoelectric layer while maintaining the thickness of the second piezoelectric layer or removing a portion of the thickness of second piezoelectric layer while maintaining the thickness of the first piezoelectric layer or removing a portion of the thickness of the first top electrode while maintaining the thickness of the second top electrode or removing a portion of the thickness of the second top electrode while maintaining the thickness of the first top electrode or removing a portion of the thickness of the mass load layer while maintaining the thickness of the second top electrode or removing a portion of the thickness the second top electrode while maintaining the thickness of the mass load layer.

37. The method as recited in claim 29, further comprising:

prior to creating the first bottom electrode and the second bottom electrode, creating a first cavity and a second cavity on a top surface of the substrate;

filling the first and the second cavities with a sacrificial material, wherein the first bottom electrode overlays part of the first cavity and part of the substrate surrounding the first cavity and wherein the second bottom electrode overlays part of the second cavity and part of the substrate surrounding the second cavity; and

subsequently, removing the sacrificial material.

38. The method as recited in claim 29, further comprising:

prior to creating the first bottom electrode and the second bottom electrode, creating a cavity on a top surface of the substrate;

filling the cavity with a sacrificial material, wherein the first bottom electrode and the second bottom electrode form a composite bottom electrode which overlays at least part of the cavity and part of the substrate surrounding the cavity; and

subsequently, removing the sacrificial material.

39. A method for fabricating a first resonator and a second resonator on a substrate, comprising:

creating a bottom mass load layer;

creating a first bottom electrode and a second bottom electrode, wherein the second bottom electrode partially overlays the substrate and wherein the temperature coefficient of the stiffness of the bottom mass load layer differs from that of the second bottom electrode;

creating a first piezoelectric layer and a second piezoelectric layer, wherein the second piezoelectric layer at least partially overlays the second bottom electrode and wherein either the bottom mass load layer partially overlays the substrate, the first bottom electrode at least partially overlays the bottom mass load layer, and the first piezoelectric layer at least partially overlays the first bottom electrode or the first bottom electrode partially overlays the substrate, the bottom mass load layer at least partially overlays the first bottom electrode, and the first piezoelectric layer at least partially overlays the bottom mass load layer; and

creating a first top electrode and a second top electrode, wherein the first top electrode is located over the first piezoelectric layer and wherein the second top electrode at least partially overlays the second piezoelectric layer.

40. The method as recited in claim 39, further comprising:

creating a mass load layer overlaying at least part of the first top electrode, wherein the first top electrode overlays at least part of the first piezoelectric structure.

41. The method as recited in claim 39, further comprising:

prior to the step creating a first top electrode and a second top electrode, creating a mass load layer overlaying at least part of the first piezoelectric structure, wherein the first top electrode overlays at least part of the mass load layer.

42. The method as recited in claim 39, wherein the mass load layer is an organic material.

43. The method as recited in claim 42, wherein the organic material is selected from the group consisting of PMMA (Polymethyl-methacrylate), PY (Polyimides), and BCB (Benzocyclobutene).

44. The method as recited in claim 39, wherein the mass load layer is a resin.

45. The method as recited in claim 44, wherein the resin is a low-k material.

46. The method as recited in claim 39, wherein the mass load layer is an oxide.

47. The method as recited in claim 39, further comprising:

removing a portion of the thickness of the first top electrode and a portion of the thickness of the second top electrode or removing a portion of the thickness of the second top electrode and a portion of the thickness of the mass load layer.

48. The method as recited in claim 39, further comprising:

removing a portion of the thickness of first piezoelectric layer while maintaining the thickness of the second piezoelectric layer or removing a portion of the thickness of second piezoelectric layer while maintaining the thickness of the first piezoelectric layer or removing a portion of the thickness of the first top electrode while maintaining the thickness of the second top electrode or removing a portion of the thickness of the second top electrode while maintaining the thickness of the first top electrode or removing a portion of the thickness of the mass load layer while maintaining the thickness of the second top electrode or removing a portion of the thickness the second top electrode while maintaining the thickness of the mass load layer.

49. The method as recited in claim 39, further comprising:

prior to creating the bottom mass load layer and the second bottom electrode, creating a first cavity and a second cavity on a top surface of the substrate;

filling the first and the second cavities with a sacrificial material, wherein the bottom mass load layer overlays part of the first cavity and part of the substrate surrounding the first cavity and wherein the second bottom electrode overlays part of the second cavity and part of the substrate surrounding the second cavity; and

subsequently, removing the sacrificial material.

50. The method as recited in claim 39, further comprising:

prior to creating the bottom mass load layer and the second bottom electrode, creating a cavity on a top surface of the substrate;

filling the cavity with a sacrificial material, wherein the first bottom electrode and the second bottom electrode form a composite bottom electrode which overlays at least part of the cavity, part of the substrate surrounding the cavity, and part of the bottom mass load layer; and

subsequently, removing the sacrificial material.