Piezoelectric-on-semiconductor micromechanical resonators with linear acoustic bandgap tethers

• US 8,624,471 B1
• Filed: 07/30/2011
• Issued: 01/07/2014
• Est. Priority Date: 07/30/2010
• Status: Expired due to Fees

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Ayazi, Farrokh, Sorenson, Logan, Fu, Jenna
• Primary Examiner(s): Dougherty, Thomas
• Application Number:
  US13/194,921
• Time in Patent Office: 892 Days
• Field of Search: 310/311, 310/348, 310351-353
• US Class Current: 310/351
• CPC Class Codes: H03H 2009/155 using MEMS techniques
• 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 9/02338 Suspension means

Abstract

Microelectromechanical resonators include a resonator body anchored to a substrate by at least one tether containing a coupled-ring linear acoustic bandgap structure therein. The coupled-ring linear acoustic bandgap structure can include a plurality of piezoelectric-on-semiconductor rings connected together by a plurality of piezoelectric-on-semiconductor tether segments. A first electrode may also be provided, which extends on the resonator body and the coupled-ring linear acoustic bandgap structure. This resonator body, which may be suspended opposite a recess in the substrate, may include a semiconductor (e.g., silicon) body having a piezoelectric layer (e.g., AlN) thereon, which extends between the semiconductor body and the first electrode. The coupled-ring linear acoustic bandgap structure may be a periodic structure, where a pitch between each of the plurality of piezoelectric-on-semiconductor rings in the at least one tether is equivalent, or a non-periodic structure.

Claims

1. A microelectromechanical resonator, comprising:

a resonator body anchored to a substrate by at least one tether comprising a coupled-ring linear acoustic bandgap structure therein, said coupled-ring linear acoustic bandgap structure comprising a plurality of piezoelectric-on-semiconductor rings connected together by a plurality of piezoelectric-on-semiconductor tether segments.

2. The resonator of claim 1, further comprising a first electrode extending on said resonator body and the coupled-ring linear acoustic bandgap structure.

3. The resonator of claim 2, wherein said resonator body comprises a semiconductor body having a piezoelectric layer thereon;

and wherein the piezoelectric layer extends between the semiconductor body and the first electrode.

4. The resonator of claim 3, further comprising a bottom electrode extending between the piezoelectric layer and the semiconductor body.

5. The resonator of claim 1, wherein the coupled-ring linear acoustic bandgap structure is a periodic structure.

6. The resonator of claim 5, wherein a pitch between each of the plurality of piezoelectric-on-semiconductor rings in the at least one tether is equivalent.

8. The resonator of claim 1, wherein the coupled-ring linear acoustic bandgap structure is a tapered structure having different sized piezoelectric-on-semiconductor rings therein.

7. A microelectromechanical resonator, comprising:

a resonator body anchored to a substrate by at least one tether comprising a coupled-ring linear acoustic bandgap structure therein, which is a tapered structure having different sized rings therein.

9. The resonator of claim 7, wherein the coupled-ring linear acoustic bandgap structure is a non-periodic structure.

10. A microelectromechanical resonator, comprising:

a resonator body anchored to a substrate by at least one tether comprising a coupled-ring linear acoustic bandgap structure therein, said at least one tether further comprising an S-wave linear acoustic bandgap structure therein.

11. The resonator of claim 10, wherein the S-wave acoustic bandgap structure is coupled in series with the coupled-ring linear acoustic bandgap structure.

12. A microelectromechanical resonator, comprising:

a resonator body having a piezoelectric layer therein and at least a pair of electrodes on the piezoelectric layer that are configured to support piezoelectric transduction in said resonator body during resonance, said resonator body anchored to a substrate by at least one tether comprising a linear acoustic bandgap structure, said linear acoustic bandgap structure comprising a linear acoustic diode structure.

13. The resonator of claim 12, wherein the linear acoustic diode structure is configured to support a directionally-asymmetric phonon dispersion characteristic as a function of frequency and acoustic wavevector.

14. A microelectromechanical resonator, comprising:

a resonator body having a piezoelectric layer therein and at least a pair of electrodes on the piezoelectric layer, said resonator body anchored to a substrate by at least one tether comprising a non-periodic linear acoustic bandgap structure containing a tapered coupled-ring linear acoustic bandgap structure having at least one of an exponentially-scaled and a linearly-scaled basis therein.

15. A microelectromechanical resonator, comprising:

a resonator body anchored to a substrate by at least one tether comprising at least one linear acoustic bandgap structure therein, said linear acoustic bandgap structure comprising a plurality of spaced-apart tether segments comprising a piezoelectric layer thereon and a first electrode on the piezoelectric layer.

16. The resonator of claim 15, wherein the first electrode extends on said resonator body.

17. The resonator of claim 16, wherein said resonator body comprises a semiconductor body having a piezoelectric layer thereon;

and wherein the piezoelectric layer extends between the semiconductor body and the first electrode.

18. The resonator of claim 17, further comprising a bottom electrode extending between the piezoelectric layer and the semiconductor body.

19. The resonator of claim 18, wherein said at least one linear acoustic bandgap structure comprises a coupled-ring linear acoustic bandgap structure.

20. The resonator of claim 15, wherein a pitch between each of the plurality of tether segments is equivalent.