Thin film piezoelectric resonator and manufacturing process thereof

• US 20050248232A1
• Filed: 04/27/2005
• Published: 11/10/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Itaya, Kazuhiko, Kawakubo, Takashi, Ohara, Ryoichi, Sano, Kenya
• Granted Patent: US 7,501,739 B2
• Time in Patent Office: Days
• US Class Current: 310/320
• CPC Class Codes: H03H 2003/023 the resonators or networks being of the membrane type
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/174 Membranes

Abstract

a thin film piezoelectric resonator includes a substrate having a cavity, and a resonance portion located on the substrate and right above the cavity. The resonance portion includes a lower electrode layer located at a side of the cavity, an upper electrode layer opposite to the lower electrode layer, and a piezoelectric thin film located between the upper electrode layer and the lower electrode layer. A side of the piezoelectric thin film and a side of the lower electrode layer are located in a common plane.

Claims

1. A thin film piezoelectric resonator, comprising:

a substrate having a cavity; and

a resonance portion located on the substrate and right above the cavity,

wherein the resonance portion includes a lower electrode layer, an upper electrode layer opposite to the lower electrode layer, and a piezoelectric thin film located between the upper electrode layer and the lower electrode layer,

wherein a side of the piezoelectric thin film and a side of the lower electrode layer are located in a common plane.

2. The thin film piezoelectric resonator according to claim 1, further comprising an insulating film covering the side of the piezoelectric thin film and the side of the lower electrode layer,

wherein a part of the upper electrode layer is located on the insulating film.

3. The thin film piezoelectric resonator according to claim 2, the insulating film includes an oxide film.

4. The thin film piezoelectric resonator according to claim 2, the insulating film includes a nitride film.

5. The thin film piezoelectric resonator according to claim 1, further comprising a conductive layer located on the substrate,

wherein a part of the lower electrode layer is located on the conductive layer.

6. The thin film piezoelectric resonator according to claim 1, wherein the cavity is a hole penetrated from a surface of the substrate to another surface thereof.

7. The thin film piezoelectric resonator according to claim 1, wherein the cavity is a hollow formed at a surface of the substrate.

8. A thin film piezoelectric resonator, comprising:

a substrate having a cavity; and

a resonance portion located on the substrate and right above the cavity,

wherein the resonance portion includes a lower electrode layer, an upper electrode layer opposite to the lower electrode layer, a first piezoelectric thin film located on the lower electrode layer, and a second piezoelectric thin film covering a side of the lower electrode and the first piezoelectric thin film,

wherein a side of the first piezoelectric thin film and a side of the lower electrode layer are located in a common plane, and the upper electrode layer is located on a side and a top of the second piezoelectric thin film.

9. The thin film piezoelectric resonator according to claim 8, wherein the second piezoelectric thin film has a thickness smaller than that of the first piezoelectric thin film.

10. The thin film piezoelectric resonator according to claim 8, further comprising a conductive layer located on the substrate,

wherein a part of the lower electrode layer is located on the conductive layer.

11. The thin film piezoelectric resonator according to claim 8, wherein the cavity is a hole penetrated from a surface of the substrate to another surface thereof.

12. The thin film piezoelectric resonator according to claim 8, wherein the cavity is a hollow formed at a surface of the substrate.

13. A thin film piezoelectric resonator, comprising:

a substrate having a cavity; and

a resonance portion located on the substrate and right above the cavity,

wherein the resonance portion includes a lower electrode layer, an upper electrode layer opposite to the lower electrode layer, a first piezoelectric thin film located on the lower electrode layer, and a second piezoelectric thin film covering a top and a first side of the first piezoelectric thin film and a first side of the lower electrode,

wherein the first side of the first piezoelectric thin film and the first side of the lower electrode layer are located in a first plane, and a second side of the first piezoelectric thin film and a first side of the second piezoelectric thin film are located in a second common plane.

14. The thin film piezoelectric resonator according to claim 13, wherein the second piezoelectric thin film has a thickness smaller than that of the first piezoelectric thin film.

15. The thin film piezoelectric resonator according to claim 13, further comprising a conductive layer located on the substrate,

wherein a part of the lower electrode layer is located on the conductive layer.

16. The thin film piezoelectric resonator according to claim 13, wherein the cavity is a hole penetrated from a surface of the substrate to another surface thereof.

17. The thin film piezoelectric resonator according to claim 13, wherein the cavity is a hollow formed at a surface of the substrate.

18. A method of manufacturing a thin film piezoelectric resonator, comprising:

depositing an electrode material on a substrate;

depositing a piezoelectric material on the deposited electrode material;

etching the deposited electrode material and the piezoelectric material using a common mask to form a lower electrode layer and a piezoelectric thin film;

forming an insulating film to cover a first part of a top of the piezoelectric thin film, a side of the piezoelectric thin film, and a side of the lower electrode layer located in a plane where the side of the piezoelectric thin film is located;

forming an upper electrode layer on a second part of the top of the piezoelectric thin film and the insulating film; and

forming a cavity right under the lower electrode layer.

19. A method of manufacturing a thin film piezoelectric resonator, comprising:

depositing an electrode material on a substrate;

depositing a piezoelectric material on the deposited electrode material;

etching the deposited electrode material and the piezoelectric material using a common mask to form a lower electrode layer and a first piezoelectric thin film;

forming a second piezoelectric thin film made of the piezoelectric material to cover a top of the first piezoelectric thin film, a side of the first piezoelectric thin film, and a side of the lower electrode layer located in a plane where the side of the first piezoelectric thin film is located;

forming an upper electrode layer on a part of a top of the second piezoelectric thin film; and

forming a cavity right under the lower electrode layer.

20. A method of manufacturing a thin film piezoelectric resonator, comprising:

depositing an electrode material on a substrate;

depositing a piezoelectric material on the deposited electrode material;

etching the deposited electrode material and the piezoelectric material using a common mask to form a lower electrode layer and a first piezoelectric thin film;

depositing the same material as the piezoelectric material to cover a top of the first piezoelectric thin film, a side of the first piezoelectric thin film, and a side of the lower electrode layer located in a plane where the side of the first piezoelectric thin film is located;

etching the materials deposited on the first piezoelectric thin film and the lower electrode layer, and a part of the first piezoelectric thin film using a common mask to expose a part of the lower electrode layer, to form a second piezoelectric thin film;

forming an upper electrode layer on a top and a side of the second piezoelectric thin film; and

forming a cavity right under the lower electrode layer.