Isolated planar mesogyroscope

• US 20050172714A1
• Filed: 04/12/2005
• Published: 08/11/2005
• Est. Priority Date: 08/12/2002
• Status: Active Grant

• Current Assignee: California Institute of Technology, The Boeing Co.
• Original Assignee: California Institute of Technology, The Boeing Co.
• Inventors: Challoner, Dorian A., Shcheglov, Kirill V.
• Granted Patent: US 7,168,318 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

An inertial sensor includes a mesoscaled disc resonator comprised of micro-machined substantially thermally non-conductive wafer with low coefficient of thermal expansion for sensing substantially in-plane vibration, a rigid support coupled to the resonator at a central mounting point of the resonator, at least one excitation electrode within an interior of the resonator to excite internal in-plane vibration of the resonator, and at least one sensing electrode within the interior of the resonator for sensing the internal in-plane vibration of the resonator. The inertial sensor is fabricated by etching a baseplate, bonding the substantially thermally non-conductive wafer to the etched baseplate, through-etching the wafer using deep reactive ion etching to form the resonator, depositing a thin conductive film on the through-etched wafer. The substantially thermally non-conductive wafer may comprise a silicon dioxide glass wafer, which is a silica glass wafer or a borosilicate glass wafer, or a silicon-germanium wafer.

Claims

1. A method of fabricating a mesoscaled resonator for an inertial sensor, comprising:

etching a baseplate;

bonding a substantially thermally non-conductive wafer to the etched baseplate; and

through-etching the substantially thermally non-conductive wafer to form a mesoscaled resonator with capacitive electrodes.

2. The method of claim 1, wherein the wafer is a silicon-germanium wafer.

3. The method of claim 1, wherein the wafer is a silicon dioxide glass wafer, and the method further comprises:

depositing a thin conductive film on the through-etched wafer; and

selectively etching the thin conductive film to render the through-etched wafer electrically conductive without otherwise effecting electrical interconnect wiring thereon.

4. The method of claim 3, wherein the silicon dioxide glass wafer is a silica glass wafer or a borosilicate glass wafer.

5. The method of claim 1, wherein the through-etching is performed using deep reactive ion etching.

6. The method of claim 1, wherein the through-etching of the wafer forms a case wall for the inertial sensor.

7. A mesoscaled resonator for an inertial sensor fabricated using the method of claim 1.

8. An inertial sensor, comprising:

a mesoscaled disc resonator comprised of a micromachined substantially thermally non-conductive material for sensing substantially in-plane vibration;

a rigid support coupled to the resonator at a central mounting point of the resonator;

at least one excitation electrode within an interior of the resonator to excite internal in-plane vibration of the resonator; and

at least one sensing electrode within the interior of the resonator for sensing the internal in-plane vibration of the resonator.

9. The inertial sensor of claim 8, wherein the substantially thermally non-conductive material comprises silicon-germanium.

10. The inertial sensor of claim 8, wherein the substantially thermally non-conductive material comprises silicon dioxide glass.

11. The inertial sensor of claim 10, wherein the silicon dioxide glass is silica glass or borosilicate glass.

12. The inertial sensor of claim 8, further comprising a baseplate supporting the rigid support, at least one excitation electrode and at least one sensing electrode.

13. The inertial sensor of claim 8, wherein the resonator includes a plurality of slots.

14. The method sensor of claim 13, wherein the plurality of slots are arranged in an annular pattern around the central mounting point of the resonator.

15. The inertial sensor of claim 13, wherein the plurality slots are arranged with substantially uniform radial spacing around the central mounting point of the resonator.

16. The inertial sensor of claim 13, wherein the excitation electrodes are each disposed within one of the plurality of slots.

17. The inertial sensor of claim 13, wherein the excitation electrodes are each disposed within one or more inner slots of one of the plurality of slots.

18. The inertial sensor of claim 13, wherein the excitation electrodes are each disposed within one of one or more outer slots of the plurality of slots.

19. The inertial sensor of claim 8, wherein the resonator is comprised of four masses, each having a simple degenerate pair of in-plane vibration modes.

20. The inertial sensor of claim 19, wherein the resonator has two degenerate in-plane system modes producing symmetric motion of the four masses for Coriolis sensing.

21. The inertial sensor of claim 8, further comprising an integral case vacuum wall formed from the wafer.

22. The inertial sensor of claim 8, wherein the wafer is bonded to the case vacuum wall with a vacuum seal.

23. The inertial sensor of claim 8, wherein the wafer includes readout electronics for the inertial sensor.

24. The inertial sensor of claim 8, further comprising an inertial wave forced to precess at constant rate.

25. The inertial sensor of claim 8, further comprising an electrostatically trimmed parameteric drive to compensate resonator damping asymmetry or case-sensitive drift.

26. The inertial sensor of claim 8, further comprising two Coriolis-coupled modes locked to an external frequency reference through use of parametric excitation.

27. The inertial sensor of claim 8, further comprising an inertial wave forced to process along a predetermined pattern through use of parametric excitation.