Lithographically Defined Multi-Standard Multi-Frequency High-Q Tunable Micromechanical Resonators

• US 20100066467A1
• Filed: 11/13/2009
• Published: 03/18/2010
• Est. Priority Date: 01/19/2007
• Status: Active Grant

• Current Assignee: Farrokh Ayazi, Gavin Kar-Fai Ho, Reza Abdolvand
• Original Assignee: Farrokh Ayazi, Gavin Kar-Fai Ho, Reza Abdolvand
• Inventors: Ho, Gavin Kar-Fai, Abdolvand, Reza, Ayazi, Farrokh
• Granted Patent: US 7,843,284 B2
• Time in Patent Office: Days
• US Class Current: 333/187
• 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

Disclosed are micromechanical resonator apparatus having features that permit multiple resonators on the same substrate to operate at different operating frequencies. Exemplary micromechanical resonator apparatus includes a support substrate and suspended micromechanical resonator apparatus having a resonance frequency. In one embodiment, the suspended micromechanical resonator apparatus comprises a device substrate that is suspended from and attached to the support substrate, a piezoelectric layer formed on the suspended device substrate, and a plurality of interdigitated upper electrodes formed on the piezoelectric layer. In another embodiment, the suspended micromechanical resonator apparatus comprises a device substrate that is suspended from and attached to the support substrate, a lower electrode formed on the suspended device substrate, a piezoelectric layer formed on the lower electrode, and a plurality of interdigitated upper electrodes formed on the piezoelectric layer. The substrate may comprise a silicon substrate, or a semiconductor-on-insulator substrate, such as a diamond on silicon substrate. Additionally, lateral frequency-adjusting electrodes may be disposed adjacent to the resonator apparatus that are separated therefrom by a capacitive gap, and which are configured to receive a direct current voltage that adjusts the resonance frequency of the resonator apparatus.

Claims

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

a resonator apparatus suspended over a substrate, said resonator apparatus comprising a composite of a device layer and a piezoelectric stack on the device layer, said piezoelectric stack comprising a conductive metal layer on the device layer, a piezoelectric layer on the conductive metal layer and a plurality of interdigitated electrodes on the piezoelectric layer.

2. The micromechanical resonator of claim 1, wherein said resonator apparatus is anchored to the substrate by a plurality of anchors.

3. The micromechanical resonator of claim 2, wherein each of the plurality of interdigitated electrodes extends across a respective one of the plurality of anchors.

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

an excitation port on the substrate, electrically connected to a first one of the plurality of interdigitated electrodes; and

a sense port on the substrate, electrically connected to a second one of the plurality of interdigitated electrodes.

5. The micromechanical resonator of claim 3, 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.

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

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

8. 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.

9. The micromechanical resonator of claim 1, further comprising a pair of frequency-adjusting electrodes disposed adjacent opposite sides of said resonator apparatus and separated from the opposite sides by respective capacitive gaps.

10. The micromechanical resonator of claim 1, wherein the piezoelectric layer comprises zinc oxide.

11. The micromechanical resonator of claim 1, wherein the conductive metal layer comprises a composite of a gold layer and a chromium layer.