FILM BULK ACOUSTIC RESONATOR AND FILM BULK ACOUSTIC RESONATOR FILTER

Abstract

A film bulk acoustic resonator includes: a support substrate; and a laminated body provided on the support substrate, a portion of the laminated body being supported by the support substrate and another portion of the laminated body being spaced from the support substrate. The laminated body includes: a first electrode primarily composed of aluminum; a piezoelectric film laminated on the first electrode and primarily composed of aluminum nitride; and a second electrode laminated on the piezoelectric film. The second electrode is primarily composed of a metal having a density of 1.9 or more times the density of aluminum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate an example FBAR according to an embodiment of the invention, where FIG. 1A is a schematic plan view and FIG. 1B is an enlarged cross-sectional view taken along line A-A.

FIG. 2A is a plan view of FIG. 1A, and FIG. 2B is a bottom view of FIG. 1A.

FIGS. 3A and 3B show an FBAR of a comparative example, where FIG. 3A is a schematic plan view and FIG. 3B is an enlarged cross-sectional view taken along line A-A.

FIG. 4 is a graph illustrating the relationship between frequency and impedance of the FBAR of FIG. 1 according to the embodiment.

FIG. 5 is a graph illustrating the relationship between frequency and impedance of the comparative FBAR of FIG. 3.

FIG. 6 is a graph showing a simulation result for the relationship between the distance in the lamination direction from the first (Al) electrode 40 and the strain energy for the FBAR of the present example shown in FIG. 1.

FIG. 7 is a graph showing a simulation result for the relationship between the distance in the lamination direction from the first (Al) electrode 40 and the strain energy for the FBAR of the comparative example shown in FIG. 3.

FIG. 8 is a Smith chart showing the impedance of the FBAR of the present example shown in FIG. 1.

FIG. 9 is a Smith chart showing the impedance of the FBAR of the comparative example shown in FIG. 3.

FIG. 10 is a graph showing the relationship between the material density used in the second electrode 60 and the strain energy fraction of the first electrode 40.

FIG. 11 is a graph showing a simulation result for the relationship between the distance in the lamination direction from the first (Al) electrode 40 and the strain energy in the second electrode 60 material for the FBAR according to the embodiment.

FIGS. 12A to 12C are process cross-sectional views illustrating a method of manufacturing an FBAR according to the embodiment.

FIGS. 13A and 13B illustrate a second example of the FBAR according to the embodiment of the invention, where FIG. 13A is a cross-sectional view and FIG. 13B is an enlarged cross-sectional view taken along line A-A.

FIG. 14 is a graph showing the relationship between the film thickness of the second (Al) electrode normalized by the thickness of the first (Al) electrode 40 and the total strain energy fraction of the first and second electrode 60.

FIG. 15 is a schematic cross-sectional view illustrating a third example of the FBAR according to the embodiment of the invention.

FIG. 16 is a schematic cross-sectional view illustrating an FBAR filter 15 based on the FBARs according to the embodiment.

FIG. 17 is an exploded plan view of the FBAR filter 15.

FIG. 18 illustrates a schematic circuit diagram of the FBAR filter 15.

FIG. 19 is a graph showing the relationship between frequency and impedance.

FIG. 20 is a circuit diagram illustrating the internal circuit configuration of a voltage controlled oscillator 165 equipped with FBARs according to the embodiment.

FIG. 21 is a schematic view of a mobile phone equipped with an FBAR according to the embodiment.

FIG. 22 is a schematic view of a PDA equipped with an FBAR according to the embodiment.

FIG. 23 is a schematic view of a notebook personal computer equipped with an FBAR according to the embodiment.

Claims

1. A film bulk acoustic resonator comprising: a support substrate; anda laminated body provided on the support substrate, a portion of the laminated body being supported by the support substrate and another portion of the laminated body being spaced from the support substrate,the laminated body including: a first electrode primarily composed of aluminum;a piezoelectric film laminated on the first electrode and primarily composed of aluminum nitride; anda second electrode laminated on the piezoelectric film and primarily composed of a metal having a density of 1.9 or more times the density of aluminum.

2. The film bulk acoustic resonator according to claim 1, wherein the metal is any one selected from the group consisting of molybdenum (Mo), copper (Cu), nickel (Ni), ruthenium (Ru), cobalt (Co), platinum (Pt), rhodium (Rh), tungsten (W), iridium (Ir), silver (Ag), and gold (Au).

3. The film bulk acoustic resonator according to claim 1, wherein the metal is any one selected from the group consisting of molybdenum (Mo), copper (Cu), and nickel (Ni).

4. The film bulk acoustic resonator according to claim 1, wherein the laminated body further includes a third electrode laminated on the second electrode, the third electrode being primarily composed of aluminum.

5. The film bulk acoustic resonator according to claim 4, wherein the third electrode has a thickness of 0.9 or less times the thickness of the first electrode.

6. The film bulk acoustic resonator according to claim 1, wherein the laminated body further includes a foundation layer laminated under the first electrode and primarily composed of an amorphous metal.

7. The film bulk acoustic resonator according to claim 6, wherein the amorphous metal is TaAl.

8. The film bulk acoustic resonator according to claim 1, wherein a thickness of the second electrode is not less than 50 nanometers and not greater than 700 nanometers.

9. The film bulk acoustic resonator according to claim 1, wherein the piezoelectric film is oriented toward c-axis.

10. A film bulk acoustic resonator comprising: a first electrode primarily composed of aluminum;a piezoelectric film laminated on the first electrode; anda second electrode laminated on the piezoelectric film and primarily composed of a metal having a density of 1.9 or more times the density of aluminum.

11. The film bulk acoustic resonator according to claim 10, wherein the piezoelectric film is primarily composed of aluminum nitride.

12. The film bulk acoustic resonator according to claim 10, wherein the metal is any one selected from the group consisting of molybdenum (Mo), copper (Cu), nickel (Ni), ruthenium (Ru), cobalt (Co), platinum (Pt), rhodium (Rh), tungsten (W), iridium (Ir), silver (Ag), and gold (Au).

13. The film bulk acoustic resonator according to claim 10, further comprising a third electrode laminated on the second electrode, the third electrode being primarily composed of aluminum.

14. The film bulk acoustic resonator according to claim 13, wherein the third electrode has a thickness of 0.9 or less times the thickness of the first electrode.

15. The film bulk acoustic resonator according to claim 10, further comprising a foundation layer laminated under the first electrode and primarily composed of an amorphous metal.

16. The film bulk acoustic resonator according to claim 15, wherein the amorphous metal is TaAl.

17. The film bulk acoustic resonator according to claim 10, wherein a thickness of the second electrode is not less than 50 nanometers and not greater than 700 nanometers.

18. The film bulk acoustic resonator according to claim 10, wherein the piezoelectric film is oriented toward c-axis.

19. A film bulk acoustic resonator filter comprising the film bulk acoustic resonator having: a support substrate; anda laminated body provided on the support substrate, a portion of the laminated body being supported by the support substrate and another portion of the laminated body being spaced from the support substrate,the laminated body including: a first electrode primarily composed of aluminum;a piezoelectric film laminated on the first electrode and primarily composed of aluminum nitride; anda second electrode laminated on the piezoelectric film and primarily composed of a metal having a density of 1.9 or more times the density of aluminum.

20. The film bulk acoustic resonator filter according to claim 19, wherein the metal is any one selected from the group consisting of molybdenum (Mo), copper (Cu), nickel (Ni), ruthenium (Ru), cobalt (Co), platinum (Pt), rhodium (Rh), tungsten (W), iridium (Ir), silver (Ag), and gold (Au).