Inter-digital bulk acoustic resonator

• US 8,803,403 B2
• Filed: 03/06/2012
• Issued: 08/12/2014
• Est. Priority Date: 12/07/2011
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Huang, Tsun-Che, Hsu, Feng-Chia, Chang, Pin, Wang, Chin-Hung
• Primary Examiner(s): Rosenau, Derek
• Assistant Examiner(s): GORDON, BRYAN P
• Application Number:
  US13/412,641
• Publication Number:
  US 20130147568A1
• Time in Patent Office: 889 Days
• Field of Search: 310/313.A, 310/313.R, 310/321
• US Class Current: 310/321
• CPC Class Codes: H03H 2009/02299 Comb-like, i.e. the beam comprising a plurality of fingers or protrusions along its length
• CPC Class Codes: H03H 2009/241 Bulk-mode MEMS resonators
• CPC Class Codes: H03H 9/02259 Driving or detection means
• CPC Class Codes: H03H 9/2463 Clamped-clamped beam resonators

Abstract

An inter-digital bulk acoustic resonator including a resonating structure, one or more input electrodes, one or more output electrodes, a substrate, and a supporting structure disposed on the substrate is provided. The resonating structure includes one or more resonating beams and a coupling beam. The resonating beams are connected at opposite two sides of the coupling beam respectively. The input electrodes and the output electrodes are arranged among the resonating beams in interlace. The input electrodes, the output electrodes, and the resonating beams are parallel to each other. Two ends of the coupling beam are connected to the supporting structure, such that the resonating structure is supported on the substrate.

Claims

1. An inter-digital bulk acoustic resonator, comprising:

a resonating structure, comprising one or more resonating beams and a coupling beam, wherein the resonating beams are respectively connected at two opposite sides of the coupling beam, and the resonating beams are perpendicular to the coupling beam;

at least one input electrode and at least one output electrode, wherein the input electrode and the output electrode are arranged in interlace between the resonating beams, the input electrode is disposed at two sides of the coupling beam, and the output electrode is disposed at two sides of the coupling beam, the input electrode, the output electrode and the resonating beams are disposed in parallel to each other, and the input electrode or the output electrode and two adjacent resonating beams respectively form a capacitor space, such that the input electrode drives the two adjacent resonating beams to vibrate or the output electrode senses a capacitance variation generated due to vibration of the two adjacent resonating beams;

a substrate; and

a supporting structure, disposed on the substrate, wherein the coupling beam or the resonating structure is supported on the substrate.

2. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the resonating beam is a bulk mode resonator, and a width of the resonating beam is (2×

n+1)×

λ

/2, wherein n is 0, 1, 2, 3, 4, . . . , and λ

is a resonating wavelength of the resonating beams in a resonating state.

3. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the input electrode comprises a first member and a second member separated from each other and located at two sides of the coupling beam, and the first member and the second member are connected through a conductive structure, the output electrode comprises a third member and a fourth member separated from each other and located at two sides of the coupling beam, and the third member and the fourth member are connected through the conductive structure.

4. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein further comprises a first axial direction is perpendicular to a second axial direction, and the input electrode, the output electrode and the resonating beams extend along the first axial direction, and are arranged in interlace along the second axial direction, wherein the first axial direction, the second axial direction and the input electrode, the output electrode, the resonating beams and the coupling beam are on a same plane.

5. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the input electrode and the output electrode are respectively connected to an application specific integrated circuit (ASIC), such that the input electrode and the output electrode drives and senses vibration of the resonating beam along the second axial direction.

6. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein a length of the coupling beam between the two resonating beams is (m+1)×

λ

/4, wherein m is 0, 1, 2, 3, 4, . . . , and λ

is a resonating wavelength of the resonating beams in a resonating state.

7. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein a length of the coupling beam between the two resonating beams is equal to a width of the coupling beam.

8. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein a cross-section of the resonating beam is a rectangle.

9. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein a material of the resonating structure is an anisotropic material.

10. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the conductive structure is a polycrystalline semiconductor material or metal.

11. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the supporting structure comprises a first supporting member and a second supporting member, the first supporting member comprises a first supporting element and a first fixing base, the first supporting element is disposed on the first fixing base, such that one end of the coupling beam is disposed on the first supporting element, and the second supporting member comprises a second supporting element and a second fixing base, the second supporting element is disposed on the second fixing base, such that another end of the coupling beam is disposed on the second supporting element.

12. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein one ends of the input electrode or the output electrode located at the same side of the coupling beam and having a same potential are connected to each other to form a digital-like structure.

13. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the input electrode is formed integrally under the coupling beam, and the input electrode has a groove at a position under the coupling beam to accommodate the input electrode, and the output electrode is formed integrally under the coupling beam, and the output electrode has a groove at a position under the coupling beam to accommodate the output electrode.

14. The inter-digital bulk acoustic resonator as claimed in claim 1, wherein the input electrode, the output electrode, the input electrode, the output electrode, the input electrode and the output electrode are sequentially disposed among the resonating beams in interlace.

15. An inter-digital bulk acoustic resonator, comprising:

a first resonating structure, comprising;

a plurality of resonating beams and a coupling beam, wherein the plurality of resonating beams are respectively connected at two opposite sides of the coupling beam, and the resonating beams are perpendicular to the coupling beam;

one or more electrodes, disposed between two adjacent resonating beams, and respectively forming capacitor gaps with the two resonating beams, wherein the electrodes drive the two adjacent resonating beams to vibrate or sense a capacitance variation generated due to vibration of the two adjacent resonating beams, and the electrodes and the resonating beams are disposed in parallel;

a second resonating structure, comprising;

a plurality of resonating beams and a coupling beam, wherein the plurality of resonating beams are symmetrically connected at two opposite sides of the coupling beam respectively, and the resonating beams are perpendicular to the coupling beam;

one or more electrodes, disposed between two adjacent resonating beams, and respectively forming capacitor gaps with the two resonating beams, wherein the electrodes drive the two adjacent resonating beams to vibrate or sense a capacitance variation generated due to vibration of the two adjacent resonating beams, and the electrodes and the resonating beams are disposed in parallel;

a substrate; and

a supporting structure, disposed on the substrate, wherein the coupling beam or the first and the second resonating structures are supported on the substrate.

16. The inter-digital bulk acoustic resonator as claimed in claim 15, wherein a width of the resonating beam is (2×

n+1)×

λ

/2, wherein n is 0, 1, 2, 3, 4, . . . , and λ

is a resonating wavelength of the resonating beams in a resonating state.

17. The inter-digital bulk acoustic resonator as claimed in claim 15, wherein a length of the coupling beam between the two resonating beams is (m+1)×

λ

/4, wherein m is 0, 1, 2, 3, 4, . . . , and λ

is a resonating wavelength of the resonating beams in a resonating state.

18. The inter-digital bulk acoustic resonator as claimed in claim 15, wherein the first resonating structure and the second resonating structure are connected in parallel and are connected through the coupling beam.

19. The inter-digital bulk acoustic resonator as claimed in claim 15, wherein the first resonating structure and the second resonating structure are separated.

20. The inter-digital bulk acoustic resonator as claimed in claim 15, wherein a width of the resonating beam of the first resonating structure is not equal to a width of the resonating beam of the second resonating structure.