Vacuum-cavity MEMS resonator

• US 20050036269A1
• Filed: 08/19/2004
• Published: 02/17/2005
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Ma, Qing, Rao, Valluri, Cheng, Peng
• Granted Patent: US 7,002,436 B2
• Time in Patent Office: Days
• US Class Current: 361/301.100
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: H03H 2009/02503 Breath-like, e.g. Lam? mode, wine-glass mode
• CPC Class Codes: H03H 2009/02511 Vertical, i.e. perpendicular to the substrate plane
• CPC Class Codes: H03H 3/0072 of microelectro-mechanical resonators or networks micromembranes or microbeams B81B2203/01; manufacture of microstructural devices in general B81C
• CPC Class Codes: H03H 9/1057 for microelectro-mechanical devices
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators
• CPC Class Codes: H03H 9/2431 Ring resonators
• CPC Class Codes: H03H 9/2457 Clamped-free beam resonators
• CPC Class Codes: H03H 9/2463 Clamped-clamped beam resonators

Abstract

A microelectromechanical (MEMS) resonator with a vacuum-cavity is fabricated using polysilicon-enabled release methods. A vacuum-cavity surrounding the MEMS beam is formed by removing release material that surrounds the beam and sealing the resulting cavity under vacuum by depositing a layer of nitride over the structure. The vacuum-cavity MEMS resonators have cantilever beams, bridge beams or breathing-bar beams.

Claims

1. A vacuum-cavity microelectromechanical (MEMS) resonator, comprising:

a first beam base atop a first passivation layer covering a surface of a substrate;

a beam fixed to the first beam base;

first and second electrodes adjacent the beam but spaced apart therefrom; and

a support structure adjacent but spaced apart from the beam and partially defining a cavity in which the beam resides, the cavity being vacuum-sealed by a layer of nitride covering the support structure.

2. The vacuum-cavity MEMS resonator of claim 1, wherein the second electrode comprises at least a portion of the support structure.

3. The vacuum-cavity MEMS resonator of claim 1, wherein the beam is fixed to the beam base at a first beam end to form a cantilever beam.

4. The vacuum-cavity MEMS resonator of claim 1, wherein the beam is fixed to a second beam base formed on the passivation layer at a second beam end to form a bridge beam.

5. The vacuum-cavity MEMS resonator of claim 1, wherein the first and second electrodes are arranged adjacent first and second opposite sides of the beam to form a breathing beam.

6. The vacuum-cavity MEMS resonator of claim 5, wherein the breathing beam is fixed to the beam base by a central support member.

7. The vacuum-cavity MEMS resonator of claim 1, wherein the support structure comprises polysilicon.

8. The vacuum-cavity MEMS resonator of claim 1, wherein the support structure fully defines the cavity in which the beam resides.

9. An apparatus, including:

a microelectromechanical (MEMS) beam sealed in a vacuum;

first and second electrodes spaced apart from the beam; and

a support structure spaced from the beam by a distance defined by a release material removed during fabrication.

10. The apparatus of claim 9, wherein the first and second electrodes are adjacent the beam.

11. The apparatus of claim 9, wherein the first and second electrodes are separated from the beam by a layer of polysilicon.

12. The apparatus of claim 9, wherein the first and second electrodes are arranged adjacent a single side of the beam.

13. The apparatus of claim 9, further including:

an electrode base between the beam and an electrode contact.

14. The apparatus of claim 13, further including:

a passivation layer between the electrode contact and a substrate.

15. The apparatus of claim 14, wherein the passivation layer comprises nitride.

16. The apparatus of claim 9, further including:

a layer of nitride to cover and vacuum-seal the support structure.

17. A system, including:

a microelectromechanical (MEMS) resonator circuit;

a beam in a vacuum with a contact of the beam coupled to the MEMS resonator circuit;

first and second electrodes adjacent the beam but spaced apart therefrom, and coupled to the MEMS resonator circuit; and

an input voltage source connected to the first electrode.

18. The system of claim 17, wherein the MEMS resonator circuit comprises:

a polarization voltage source connected to the beam; and

an inductor and voltage output line connected in parallel with the second electrode.

19. The system of claim 17, wherein the input voltage source comprises an antenna.

20. The system of claim 17, further including:

a support structure adjacent but spaced apart from the beam and partially defining a cavity in which the beam resides, the cavity being vacuum-sealed by a layer of nitride.