Thin-Film Bulk Acoustic Resonators Having Reduced Susceptibility to Process-Induced Material Thickness Variations

• US 20100194246A1
• Filed: 01/30/2009
• Published: 08/05/2010
• Est. Priority Date: 01/30/2009
• Status: Abandoned Application

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Wang, Ye, Bhugra, Harmeet
• Application Number:
  US12/363,142
• Publication Number:
  US 20100194246A1
• Time in Patent Office: Days
• US Class Current: 310/365
• CPC Class Codes: H03H 9/02047 Treatment of substrates
• CPC Class Codes: H03H 9/02094 of adherence
• CPC Class Codes: H03H 9/56 Monolithic crystal filters

Abstract

Thin-film bulk acoustic resonators include a resonator body (e.g., silicon body), a bottom electrode on the resonator body and a piezoelectric layer on the bottom electrode. At least one top electrode is also provided on the piezoelectric layer. In order to inhibit process-induced variations in material layer thicknesses from significantly affecting a desired resonant frequency of the resonator, the top and bottom electrodes are fabricated to have a combined thickness that is proportional to a target thickness of the piezoelectric layer extending between the top and bottom electrodes.

Claims

1. A thin-film bulk acoustic resonator, comprising:

a resonator body;

a bottom electrode on said resonator body;

a piezoelectric layer on said bottom electrode; and

a top electrode on said piezoelectric layer, said top and bottom electrodes having a combined thickness of t₃ within the following range;

2. The resonator of claim 1, wherein said bottom and top electrodes comprise an electrically conductive material selected from a group consisting of molybdenum (Mo) and aluminum (Al).

3. The resonator of claim 1, wherein said piezoelectric layer comprises aluminum nitride (AlN).

4. The resonator of claim 1, further comprising an electrically insulating compensation layer on top or bottom of said resonator body.

5. The resonator of claim 4, wherein said compensation layer is a silicon dioxide layer.

6. The resonator of claim 4, further comprising an adhesion layer between said compensation layer and said bottom electrode.

7. The resonator of claim 6, wherein said adhesion layer comprises the same material as said piezoelectric layer.

8. The resonator of claim 6, wherein said adhesion layer comprises the same material as said piezoelectric layer;

and wherein t₂ is a combined thickness of said piezoelectric layer and said adhesion layer.

9. The resonator of claim 1, wherein said top and bottom electrodes have a combined thickness of t₃ within the following range:

10. A thin-film bulk acoustic resonator, comprising:

a resonator body;

a compensation layer on top or bottom of said resonator body;

a bottom electrode on said resonator body;

a piezoelectric layer on said bottom electrode; and

a top electrode on said piezoelectric layer, said top and bottom electrodes having a combined thickness of t₃ within the following range;

11. The acoustic resonator of claim 10, wherein said compensation layer is an electrically insulating dielectric layer.

12. The resonator of claim 10, wherein said bottom and top electrodes comprise an electrically conductive material selected from a group consisting of molybdenum (Mo) and aluminum (Al).

13. The resonator of claim 10, wherein said piezoelectric layer comprises aluminum nitride (AlN).

14. The resonator of claim 10, further comprising an adhesion layer between said compensation layer and said bottom electrode.

15. The resonator of claim 14, wherein said adhesion layer comprises the same material as said piezoelectric layer;

and wherein t₂ is a combined thickness of said piezoelectric layer and said adhesion layer.

16. The resonator of claim 15, wherein said top and bottom electrodes have a combined thickness of t₃ within the following range:

17. The resonator of claim 10, wherein said top and bottom electrodes have a combined thickness of t₃ within the following range:

18. A thin-film bulk acoustic resonator, comprising:

a resonator body;

a bottom electrode comprising molybdenum, on said resonator body;

a piezoelectric layer on said bottom electrode; and

a top electrode comprising molybdenum on said piezoelectric layer, said top and bottom electrodes having a combined thickness in a range from greater than about 0.12 to about 0.24 times a thickness of said piezoelectric layer.

19. The resonator of claim 18, further comprising a piezoelectric adhesion layer on said resonator body.

20. The resonator of claim 19, further comprising a compensation layer on top or bottom of said resonator body.

21. The resonator of claim 20, wherein said compensation layer comprises silicon dioxide.

22. A thin-film bulk acoustic resonator, comprising:

a resonator body;

a bottom electrode comprising aluminum, on said resonator body;

a piezoelectric layer on said bottom electrode; and

a top electrode comprising aluminum on said piezoelectric layer, said top and bottom electrodes having a combined thickness in a range from greater than about 0.46 to about 0.93 a thickness of said piezoelectric layer.

23. The resonator of claim 22, further comprising a piezoelectric adhesion layer extending between said bottom electrode and said resonator body.

24. The resonator of claim 23, further comprising a compensation layer on top or bottom of said resonator body.

25. The resonator of claim 24, wherein said compensation layer comprises silicon dioxide.