THIN FILM TUNING-FORK TYPE INFLECTION RESONATOR AND ELECTRIC SIGNAL PROCESSING ELEMENT

Abstract

A compact resonator has a wide bandwidth and a small variation of the specific vibration frequency. The resonator is a thin film tuning-fork type inflection resonator in which a thin film made of a piezoelectric material is formed on a substrate on which a lower electrode is formed, and an upper electrode is formed on the piezoelectric thin film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a first embodiment of the present invention;

FIG. 2 shows a top view of a resonator in the first embodiment of the present invention;

FIG. 3 is a bottom view of the resonator in the first embodiment of the present invention;

FIG. 4A is a cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4B is another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4C is still another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4D is still another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4E is still another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4F is still another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4G is still another cross-sectional view of the resonator showing, in sequential order, the manufacturing processes in the first embodiment of the present invention;

FIG. 4H is a cross-sectional view of a resonator in another embodiment of the present invention;

FIG. 5A is an explanatory cross-sectional view of a vibrating part of a typical conventional quartz resonator;

FIG. 5B is a cross-sectional view of a vibrating part of the resonator shown in FIG. 2, taken along a line A-A, in association with the present invention;

FIG. 6 shows an example of the relationship between thickness of a lower electrode and degradation of its excitation efficiency;

FIG. 7 shows an example of the relationship between the bandwidth and the ratio of (the portion of the electrode excitation part occupied in the vibrating part) to (the total length of the vibrating part);

FIG. 8 is a top view of a resonator for describing another preferred embodiment of the present invention;

FIG. 9 is a cross-sectional view of the resonator taken along a line A-A shown in FIG. 8;

FIG. 10 is a top view of a resonator for describing another preferred embodiment of the present invention;

FIG. 11 shows an example of the relationship between the thickness of a piezoelectric material and the deviation of the vibration frequency of a resonator;

FIG. 12 is a top view of a resonator in another preferred embodiment of the present invention;

FIG. 13 shows an example of the relationship between the depth of the recess and the deviation of the vibration frequency of a resonator;

FIG. 14 is a top view of a resonator in a preferred embodiment of the present invention;

FIG. 15 is a top view of a resonator in a preferred embodiment of the present invention;

FIG. 16 is a top view of a resonator in a preferred embodiment of the present invention;

FIG. 17 is a circuit diagram of an equivalent circuit for which the resonator of the present invention is applied;

FIG. 18 is another circuit diagram of an equivalent circuit for which the resonator of the present invention is applied;

FIG. 19 is a cross-sectional view of a resonator of the present invention, which is mounted in a device;

FIG. 20 is another example of a circuit diagram of an equivalent circuit in which a resonator of the present invention is applied; and

FIG. 21 is a top view of the arrangement of a resonator of the present invention and other electric parts to be integrated on a substrate.

Claims

1. A thin film tuning-fork type inflection resonator, comprising: a piezoelectric film formed in a tuning-fork shape;a first metallic electrode formed on a first surface of said piezoelectric film; anda second metallic electrode formed on a second surface of said piezoelectric film opposite said first surface of said piezoelectric film;wherein said first metallic electrode is deposited as a film on said piezoelectric film; andwherein said piezoelectric film is formed so as to cover said second metallic electrode.

2. The thin film tuning-fork type inflection resonator according to claim 1, wherein said tuning-fork-shaped piezoelectric film further includes a vibrating part and a supporting part,wherein said first and second metallic electrodes are formed at least on part of said supporting part and on part of said vibrating part, and said first and second metallic electrodes formed on said vibrating part are positioned within the distance of ⅔ from said root to said tip.

3. The thin film tuning-fork type inflection resonator according to claim 2, wherein said first metallic electrode includes a plurality of electrode films and said second metallic electrode consists of a single electrode film.

4. The thin film tuning-fork type inflection resonator according to claim 2, wherein at least one of said plurality of vibrating parts has at least one of a recess at a side surface thereof, a projection at said side surface, or a hole passing through a portion between said first surface and said second surface.

5. The thin film tuning-fork type inflection resonator according to claim 4, wherein all of said plurality of vibrating has at least two of said recess, said projection,.and said hole.

6. An electric signal processing device having said thin film turning-fork type inflection resonator described in claim 1, and further comprising: a nonmetallic substrate fixed to said thin film turning-fork type inflection resonator; anda first semiconductor substrate including at least an electronic active element,wherein said nonmetallic substrate and said first semiconductor substrate are mounted on the same base.

7. The electric signal processing device according to claim 6, wherein the nonmetallic substrate is fixed to a plurality of said thin film tuning-fork type inflection resonators.

8. The electric signal processing device according to claim 6, wherein said nonmetallic substrate is a second semiconductor substrate, andwherein said second semiconductor substrate includes at least an electrical active element.

9. A resonator manufacturing method comprising the steps of: forming a lower electrode above a substrate by depositing and etching a material film of said lower electrode;forming a piezoelectric thin film on said lower electrode in a tuning fork shape, by depositing and etching said piezoelectric thin film to form said tuning fork shape; andforming an upper electrode on said piezoelectric thin film by depositing and etching a material film of said upper electrode.

10. A resonator manufacturing method of resonator according to claim 9, further comprising: forming a sacrificial layer before forming said lower electrode; andremoving said sacrificial layer,wherein at least a part of said lower electrode is formed on said sacrificial layer in said step of forming said lower electrode.

11. A resonator manufacturing method according to claim 10, wherein said substrate is a silicon substrate and said sacrificial layer is a PSG film.

12. A tuning-fork type inflection resonator comprising: a piezoelectric element formed into a tuning fork shape;a first electrode formed on a first side of the piezoelectric element and connected to a first terminal;a second electrode formed on the first side of the piezoelectric element and connected to a second terminal; anda third electrode formed on a second side of the piezoelectric element opposite to the first side, wherein the third electrode is a single electrode.

13. A tuning-fork type inflection resonator according to claim 12, wherein the third electrode is a floating electrode.

14. A tuning-fork type inflection resonator according to claim 12, wherein the third electrode is connected to a ground potential.

15. A tuning-fork type inflection resonator according to claim 12, wherein the first, second, and third electrodes are formed by a film manufacturing method.

16. A tuning-fork type inflection resonator comprising: a piezoelectric element formed into a tuning fork shape having a vibrating part, a pedestal part, and a supporting part;a first electrode formed on a first side of the piezoelectric element; anda second electrode formed on a second side of the piezoelectric element opposite to the first side,wherein said first and second electrodes are formed on root portions of said vibrating part, and there are no first and second electrodes at tip portions of said vibrating part.

17. A tuning-fork type inflecting resonator according to claim 16, wherein said first and second electrodes are formed on portions of said vibrating part within a distance of ⅔ from said root of said vibrating part.

18. A tuning-fork inflecting resonator according to claim 16, wherein at lease one of a recess, a projection, and a hole passing through the first and second sides, is formed on the vibrating part where there is not formed said first and second electrodes.