Micromechanical bulk acoustic mode resonators having interdigitated electrodes and multiple pairs of anchor supports

• US 7,924,119 B1
• Filed: 11/10/2010
• Issued: 04/12/2011
• Est. Priority Date: 01/19/2007
• 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: Ho, Gavin Kar-Fal, Abdolvand, Reza, Ayazi, Farrokh
• Primary Examiner(s): Takaoka; Dean O
• Application Number:
  US12/943,319
• Time in Patent Office: 153 Days
• Field of Search: 333/186, 333/187, 333/189, 333/191, 333/197
• US Class Current: 333/186
• CPC Class Codes: H03H 2003/027 the resonators or networks being of the microelectro-mechanical [MEMS] type
• CPC Class Codes: H03H 2009/02196 operating on the FBAR element, e.g. by direct application of a tuning DC voltage
• 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 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators

Abstract

A micromechanical resonator operable in a bulk acoustic mode includes a resonator apparatus suspended over a substrate by a plurality of pairs of anchors. The resonator apparatus includes a conductive metal layer, a piezoelectric layer on the conductive metal layer and a plurality of interdigitated electrodes on the piezoelectric layer. The interdigitated electrodes are configured so that a total number of electrode fingers in the plurality of interdigitated electrodes is greater than a total number of the plurality of pairs of anchors.

Claims

1. A micromechanical resonator operable in a bulk acoustic mode, comprising:

a resonator apparatus suspended over a substrate by a plurality of pairs of anchors, said resonator apparatus comprising a conductive metal layer, a piezoelectric layer on the conductive metal layer and a plurality of interdigitated electrodes on the piezoelectric layer; and

wherein a total number of electrode fingers in the plurality of interdigitated electrodes is greater than a total number of the plurality of pairs of anchors.

2. The micromechanical resonator of claim 1, wherein the plurality of pairs of anchors includes a first pair of anchors on opposite sides of said resonator apparatus;

wherein the plurality of interdigitated electrodes includes a first electrode that extends across a first one of the first pair of anchors and a second electrode that extends across a second one of the first pair of anchors.

3. The micromechanical resonator of claim 2, further comprising:

an excitation port on the substrate, electrically connected to the first electrode; and

a sense port on the substrate, electrically connected to the second electrode.

4. The micromechanical resonator of claim 1, wherein said resonator apparatus is suspended over a cavity in the substrate;

and wherein said resonator apparatus comprises an electrically insulating layer on a bottom surface of the device layer that faces the cavity.

5. The micromechanical resonator of claim 1, wherein a pitch between said plurality of interdigitated electrodes is uniform.

6. The micromechanical resonator of claim 1, wherein the device layer is a single crystal silicon device layer.

7. The micromechanical resonator of claim 1, wherein the device layer comprises a material selected from a group consisting of diamond, nanocrystalline diamond, silicon carbide, silicon-germanium and gallium arsenide.