Temperature-compensated film bulk acoustic resonator (FBAR) devices
View Patent ↗The temperature-compensated film bulk acoustic resonator (FBAR) device comprises an FBAR stack. The FBAR stack comprises an FBAR and a temperature-compensating element. The FBAR is characterized by a resonant frequency having a temperature coefficient, and comprises opposed planar electrodes and a piezoelectric element between the electrodes. The piezoelectric element has a temperature coefficient on which the temperature coefficient of the resonant frequency depends at least in part. The temperature-compensating element has a temperature coefficient opposite in sign to the temperature coefficient of the piezoelectric element.
1. A temperature-compensated film bulk acoustic resonator (FBAR) device, comprising:
an FBAR stack, comprising:
an FBAR characterized by a resonant frequency having a temperature coefficient, the FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, the piezoelectric element having a temperature coefficient on which the temperature coefficient of the resonant frequency depends at least in part, and
a temperature-compensating element having a temperature coefficient opposite in sign to the temperature coefficient of the piezoelectric element, and the temperature-compensating element comprises one of: a niobium-molybdenum (Nb—Mo): a cobalt—palladium (Co—Pd) alloy: or a niobium-molybdenum (Nb—Mo) alloy.
2. The FBAR device of claim 1 , in which the temperature-compensating element comprises a temperature-compensating layer juxtaposed with one of the electrodes.
3. The FBAR device of claim 2 , in which the temperature-compensating element additionally comprises an additional temperature-compensating layer juxtaposed with the other of the electrodes.
4. The FBAR device of claim 2 , in which the temperature-compensating layer is located between the one of the electrodes and the piezoelectric element.
5. The FBAR device of claim 2 , in which:
the FBAR is a lower FBAR; and
the FBAR device additionally comprises:
an upper FBAR stacked on the lower FBAR, the upper FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, and
an acoustic decoupler between the FBARs.
6. The FBAR device of claim 5 , in which the temperature-compensating element comprises a temperature-compensating layer juxtaposed with one of the electrodes of each of the FBARs.
7. The FBAR device of claim 6 , in which in each of the FBARs, the temperature-compensating layer is between the one of the electrodes and the piezoelectric element thereof.
8. The FBAR device of claim 6 , in which in each of the FBARs, the one of the electrodes is juxtaposed with the acoustic decoupler.
9. The FBAR device of claim 5 , in which in each of the FBARs, one of the electrodes is juxtaposed with the acoustic decoupler.
10. The FBAR device of claim 5 , in which:
the first FBAR, the second FBAR and the acoustic decoupler constitute a first decoupled stacked bulk acoustic resonator (DSBAR);
the FBAR stack additionally comprises a second DSBAR, comprising a lower FBAR, an upper FBAR stacked on the lower FBAR, and an acoustic decoupler between the FBARs; and
the FBAR device additionally comprises:
a first electrical circuit interconnecting the lower FBARs, and
a second electrical circuit interconnecting the upper FBARs.
11. The FBAR device of claim 10 , in which the temperature-compensating element comprises a temperature-compensating layer juxtaposed with one of the electrodes of each of the FBARs.
12. The FBAR device of claim 11 , in which in each of the FBARs, the temperature-compensating layer is between the one of the electrodes and the piezoelectric element thereof.
13. The FBAR device of claim 11 , in which in each of the FBARs, the one of the electrodes is juxtaposed with the acoustic decoupler.
14. The FBAR device of claim 10 , in which in each of the FBARs, one of the electrodes is juxtaposed with the acoustic decoupler.
15. The FBAR device of claim 2 , in which:
the FBAR is a first FBAR;
the FBAR stack additionally comprises one or more additional FBARs; and
the FBARs are interconnected as a ladder filter.
16. The FBAR device of claim 15 , in which the temperature-compensating element comprises a temperature-compensating layer juxtaposed with one of the electrodes of each of the FBARs.
17. The FBAR device of claim 1 , in which the temperature-compensating element comprises a temperature-compensating layer embedded in the piezoelectric element.
18. The FBAR device of claim 17 , in which:
the FBAR is a lower FBAR; and
the FBAR device additionally comprises:
an upper FBAR stacked on the lower FBAR, the upper FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, and
an acoustic decoupler between the FBARs.
19. The FBAR device of claim 18 , in which the temperature-compensating element comprises a temperature-compensating layer embedded in the piezoelectric element of each of the FBARs.
20. The FBAR device of claim 18 , in which;
the lower FBAR, the upper FBAR and the acoustic decoupler constitute a first decoupled stacked bulk acoustic resonator (DSBAR);
the FBAR stack additionally comprises a second DSBAR, comprising a lower FBAR, an upper FBAR, an acoustic decoupler between the FBARs; and
the FBAR device additionally comprises:
a first electrical circuit interconnecting the lower FBARs, and
a second electrical circuit interconnecting the upper FBARs.
21. The FBAR device of claim 20 in which the temperature-compensating element comprises a temperature-compensating layer embedded in the piezoelectric element of each of the FBARs.
22. The FBAR device of claim 17 , in which:
the FBAR is a first FBAR;
the FBAR stack additionally comprises one or more additional FBARs; and
the FBARs are interconnected as a ladder filter.
23. The FBAR device of claim 22 , in which the temperature-compensating element comprises a temperature-compensating layer embedded in the piezoelectric element of each of the FBARs.
24. The FBAR device of claim 1 , in which the temperature-compensating element comprises one of the electrodes.
25. The FBAR device of claim 24 , in which:
the FBAR is a lower FBAR;
the FBAR device additionally comprises:
an upper FBAR stacked on the lower FBAR, the upper FBAR comprising a piezoelectric element, and
an acoustic decoupler between the FBARs; and
the temperature-compensating element additionally comprises opposed temperature-compensating layers between which the piezoelectric element of the upper FBAR is located.
26. The FBAR device of claim 25 , in which the temperature-compensating element comprises one of the electrodes of each of the FBARs.
27. The FBAR device of claim 25 , in which:
the lower FBAR, the upper FBAR and the acoustic decoupler constitute a first decoupled stacked bulk acoustic resonator (DSBAR);
the FBAR stack additionally comprises a second DSBAR, comprising a lower FBAR, an upper FBAR, an acoustic decoupler between the FBARs; and
the FBAR device additionally comprises:
a first electrical circuit interconnecting the lower FBARs, and
a second electrical circuit interconnecting the upper FBARs.
28. The FBAR device claim 27 , in which the temperature-compensating element comprises one of the electrodes of each of the FBARs.
29. The FBAR device of claim 24 , in which:
the FBAR is a first FBAR;
the FBAR stack additionally comprises one or more additional FBARs; and
the FBARs are interconnected as a ladder filter.
30. The FBAR device of claim 29 , in which the temperature-compensating element comprises one of the electrodes of each of the FBARs.
31. The FBAR device of claim 1 , in which the cobalt-palladium alloy has a palladium fraction in the range from about 93% to about 95%.
32. The FBAR device of claim 1 , in which the niobium-molybdenum alloy has a molybdenum fraction in the range from about 17% to about 51%.
33. The FBAR device of claim 1 , in which the niobium-molybdenum alloy has a molybdenum fraction in the range from about 32% to about 36%.
34. The FBAR device of claim 1 , in which the cobalt-palladium alloy has a palladium fraction in the range from about 92% to about 96%.
35. An acoustic device, comprising an acoustic propagation path having a propagation time-related property, the propagation time-related property having a temperature coefficient, the acoustic propagation path comprising:
an acoustic propagation element having a temperature coefficient on which the propagation time-related property of the acoustic propagation path depends at least in part; and
a temperature-compensating element having a temperature coefficient opposite in sign to the temperature coefficient of the acoustic propagation element, and the temperature-compensating element comprises one of: a niobium-molybdenum (Nb—Mo);
a cobalt-palladium (Co—Pd) alloy; or a niobium-molybdenum (Nb—Mo) alloy.
36. A temperature-compensated film bulk acoustic resonator (FBAR) device, comprising:
an FBAR stack, comprising:
an FBAR characterized by a resonant frequency having a temperature coefficient, the FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, the piezoelectric element having a temperature coefficient on which the temperature coefficient of the resonant frequency depends at least in part, and a temperature-compensating element having a temperature coefficient opposite in sign to the temperature coefficient of the piezoelectric element, wherein the temperature-compensating element comprises a ferroelectric material, which comprises one of:
lead nickel niobate (Pb(Ni x Nb i-x )O 3 in which the nickel fraction x is about one third; nepheline (KAlSiO 4 )(NaAlSiO 4 ) 3 ; or zirconium tungstate (ZrW 2 O 8 ).
37. An acoustic device, comprising an acoustic propagation path having a propagation time-related property, the propagation time-related property having a temperature coefficient, the acoustic propagation path comprising:
an acoustic propagation element having a temperature coefficient on which the propagation time-related property of the acoustic propagation path depends at least in part; and
a temperature-compensating element having a temperature coefficient opposite in sign to the temperature coefficient of the acoustic propagation element, wherein the temperature compensating element comprises a ferroelectric material, which comprises one of:
lead nickel niobate (Pb(Ni x Nb 1-x )O 3 in which the nickel fraction x is about one third; nepheline (KAlSiO 4 )(NaAlSiO 4 ) 3 ; or zirconium tungstate (ZrW 2 O 8 ).