Thin-Film Piezoelectric-on-Insulator Resonators Having Perforated Resonator Bodies Therein

• US 20100060111A1
• Filed: 08/04/2009
• Published: 03/11/2010
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Sorenson, Logan D., Ayazi, Farrokh
• Granted Patent: US 7,888,843 B2
• Time in Patent Office: Days
• US Class Current: 310/367
• CPC Class Codes: H03B 2200/0046 including measures to switch the gain of an amplifier
• CPC Class Codes: H03B 2200/0048 including measures to switch the frequency band, e.g. by harmonic selection
• CPC Class Codes: H03B 5/326 the resonator being an acoustic wave device, e.g. SAW or BAW device
• CPC Class Codes: H03B 5/366 and comprising means for varying the frequency by a variable voltage or current
• CPC Class Codes: H03H 2009/02173 of film bulk acoustic resonators [FBAR]
• CPC Class Codes: H03H 2009/0233 comprising perforations
• CPC Class Codes: H03H 2009/02496 Horizontal, i.e. parallel to the substrate plane
• CPC Class Codes: H03H 2009/241 Bulk-mode MEMS resonators
• CPC Class Codes: H03H 9/02228 Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
• CPC Class Codes: H03H 9/02259 Driving or detection means
• CPC Class Codes: H03H 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
• CPC Class Codes: H03H 9/2463 Clamped-clamped beam resonators

Abstract

A micro-electromechanical resonator self-compensates for process-induced dimensional variations by using a resonator body having a plurality of perforations therein. These perforations may be spaced along a longitudinal axis of the resonator body, which extends orthogonal to a nodal line of the resonator body. These perforations, which may be square or similarly-shaped polygonal slots, may extend partially or entirely though the resonator body and may be defined by the same processes that are used to define the outer dimensions (e.g., length, width) of the resonator body.

Claims

1. A micro-electromechanical resonator, comprising:

a resonator body anchored to a substrate, said resonator body having a plurality of perforations therein extending at least substantially therethrough.

2. The resonator of claim 1, wherein a shape, size, depth and location of the plurality of perforations are sufficient, in combination, to reduce a susceptibility of the resonator to process-induced variations in resonant frequency relative to an otherwise equivalent resonator that omits the plurality of perforations.

3. The resonator of claim 1, wherein a shape, size, depth and location of the plurality of perforations in said resonator body are configured to render a resonant frequency of the resonator less susceptible to changes caused by process-induced variations in dimensions of said resonator body, relative to an otherwise equivalent resonator having a resonator body that is changed in dimension by the same process-induced variations, but is free of the plurality of perforations.

4. The resonator of claim 2, wherein said resonator body is anchored on opposite sides to the substrate;

and wherein said resonator body is configured so that a nodal line of said resonator body extends between anchors on the opposite sides of the substrate.

5. The resonator of claim 4, wherein said resonator body is suspended opposite an opening in the substrate.

6. The resonator of claim 1, further comprising a first electrode on a surface of said resonator body, said first electrode extending adjacent a first side of the plurality of perforations.

7. The resonator of claim 6, further comprising a second electrode on a surface of said resonator body, said second electrode extending adjacent a second side of the plurality of perforations.

8. The resonator of claim 1, wherein the plurality of perforations are arranged as a two-dimensional array of rectangular slots that extend entirely through said resonator body.

9. The resonator of claim 1, wherein said resonator body comprises a piezoelectric layer;

and wherein the plurality of perforations extend through the piezoelectric layer.

10. The resonator of claim 1, wherein a nodal line of said resonator body is uninterrupted by the plurality of perforations.

11. The resonator of claim 1, wherein said resonator body comprises an aluminum nitride piezoelectric layer and molybdenum bottom and top electrodes;

and wherein a combined thickness of the bottom and top electrodes is about 0.1 times at thickness of the aluminum nitride piezoelectric layer.

12. A thin-film piezoelectric-on-substrate resonator, comprising:

a resonator body anchored to a substrate, said resonator body having a plurality of perforations therein that extend along a longitudinal axis of said resonator body that is orthogonal to a nodal line of said resonator body.

13. The resonator of claim 12, wherein the plurality of perforations are square-shaped.

14. The resonator of claim 12, wherein said resonator body comprises first and second anchors on opposite sides thereof, connected to the substrate.

15. The resonator of claim 14, further comprising first and second electrodes extending across the first and second anchors, respectively.

16. The resonator of claim 12, wherein said resonator body comprises a piezoelectric layer;

and wherein the plurality of perforations extend through the piezoelectric layer.