DISC RESONATOR GYROSCOPE WITH IMPROVED FREQUENCY COINCIDENCE AND METHOD OF MANUFACTURE

• US 20090095077A1
• Filed: 10/12/2007
• Published: 04/16/2009
• Est. Priority Date: 10/12/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: DeNatale, Jeffrey F., Stupar, Philip A.
• Granted Patent: US 7,987,714 B2
• Time in Patent Office: Days
• US Class Current: 73/504.13
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

A disc resonator gyroscope (DRG) and method of manufacture. The DRG has a surrounding pattern of bond metal having a symmetry related to the symmetry of a resonator device wafer that enables more even dissipation of heat from a resonator device wafer of the DRG during an etching operation. The metal bond frame eliminates or substantially reduces the thermal asymmetry that the resonator device wafer normally experiences when a conventional, square bond frame is used, which in turn can cause geometric asymmetry in the widths of the beams that are etched into the resonator device wafer of the DRG.

Claims

1. A method of manufacturing a disc resonator gyroscope (DRG) that produces improved geometric symmetry of the gyroscope, comprising:

forming a resonator device wafer,

forming a substrate base wafer having a patterned metal bonding layer on one surface thereof, the patterned metal bonding layer having a first symmetry;

bonding said resonator device wafer to said patterned metal bonding layer;

etching said resonator device wafer in accordance with a pattern having a second symmetry to remove regions of material from said resonator device wafer, said second symmetry having a relationship to said first symmetry; and

said first and second symmetries enhancing thermal symmetry in said resonator device wafer during said etching operation to reduce geometric asymmetry in said resonator device wafer during said etching operation.

2. The method of claim 1, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a plurality of arcuately shaped metal bonding regions with a desired symmetry disposed uniformly about a peripheral area of the resonator device wafer.

3. The method of claim 1, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a metal bonding layer that includes a non-uniform area when viewed in plan.

4. The method of claim 3, wherein forming said substrate base wafer having a metal bonding layer that includes a non-uniform area includes forming a square shaped metal bond layer around the resonator device wafer, wherein the metal bonding layer includes a plurality of corner portions between the resonator device wafer, with the corner portions filled with metal.

5. The method of claim 1, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a plurality of metal bonding pads disposed about a peripheral portion of the resonator device wafer on the substrate base wafer.

6. The method of claim 5, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a plurality of circular metal bonding pads formed in a general circumferential pattern about a peripheral area of said substrate base wafer.

7. The method of claim 1 wherein:

forming a substrate base wafer comprises forming a substrate base wafer from silicon; and

forming a resonator device wafer comprises forming a resonator device wafer from silicon.

8. The method of claim 1, wherein:

forming a substrate base wafer comprises forming a substrate base wafer from quartz; and

forming a resonator device wafer comprises forming a resonator device wafer from quartz.

9. The method of claim 1, wherein said bonding operation comprises one of:

thermocompression bonding;

fusion bonding;

transient liquid phase bonding; and

eutectic bonding.

10. The method of claim 1, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a patterned gold bonding layer.

11. The method of claim 1, wherein forming a substrate base wafer having a patterned metal bonding layer comprises forming a substrate base wafer having a patterned gold bonding layer that also includes layers to improve adhesion and layers to prevent interdiffusion.

12. The method of claim 11, wherein the adhesion layers are selected from one of chromium or titanium and the diffusion barriers are selected from among Titanium Tungsten (TiW), Titanium Nitride (TiN), Tungsten Nitride (WN), Platinum (Pt), Molybdenum (Mo), and Molybdenum Nitride (MoN).

13. The method of claim 1, wherein forming a resonator device wafer comprises forming a resonator device wafer from Silicon.

14. The method of claim 1, wherein forming a resonator device wafer comprises forming a resonator device wafer from quartz.

15. A method of manufacturing a disc resonator gyroscope (DRG) that produces improved geometric symmetry of the gyroscope, comprising:

forming a resonator device wafer;

forming a substrate base wafer on one surface thereof having a circumferential metal bonding layer, the circumferential metal bonding layer further being formed about a peripheral area where said resonator device wafer will be attached to said substrate base wafer in a subsequent manufacturing operation;

bonding said resonator device wafer to said substrate base wafer;

forming a pattern that defines areas of material that need to be removed from said resonator device wafer to form resonator elements that are responsive to mechanical vibration energy;

using said pattern to etch said resonator device wafer so that said resonator device wafer has a symmetry related to said circumferential metal bonding layer, and such that regions of material of said resonator device wafer are removed from said resonator device wafer to form said resonator elements; and

said symmetry of said resonator device wafer relative to said circumferential metal bonding layer reducing thermal asymmetry in said resonator device wafer during said etching to reduce geometric asymmetry of said resonator device wafer.

16. The method of claim 15, wherein forming a substrate base wafer having a circumferential metal bonding layer comprises forming a substrate base wafer having a plurality of arcuately shaped metal bonding pads disposed in a general circumferential pattern around said resonator device wafer.

17. The method of claim 15, wherein forming a substrate base wafer having a circumferential metal bonding layer comprises forming a substrate base wafer having a plurality of independent metal bond pads around said resonator device wafer.

18. The method of claim 17, wherein forming a substrate base wafer having a plurality of independent metal bond pads comprises forming a substrate base wafer having a plurality of independent, generally circular, metal bond pads around said resonator device wafer.

19. The method of claim 15, wherein bonding said resonator device wafer to said substrate base wafer comprises one of:

thermocompression bonding said resonator device wafer to said substrate base wafer;

fusion bonding said resonator device wafer to said substrate base wafer;

transient liquid phase bonding said resonator device wafer to said substrate base wafer; and

eutectic bonding said resonator device wafer to said substrate base wafer.

20. A disc resonator gyroscope (DRG) comprising:

a substrate base wafer having a patterned metal bonding layer on one surface about a peripheral area thereof;

said patterned metal bonding layer having a first symmetry;

a resonator device wafer bonded to said patterned metal bonding layer within an area circumscribed by said patterned metal bonding layer, the resonator device wafer having etched areas where material thereof has been removed to form vibratory structure, and said etched areas having a second symmetry;

said first and second symmetries having a relation to enable generally uniform thermal conductivity in said resonator device wafer during etching of said resonator device wafer to reduce a geometric asymmetry of said vibratory structure formed by said etched areas.

21. The disc resonator gyroscope of claim 20, wherein said resonator device wafer is one of:

thermocompression bonded to said substrate base wafer;

fusion bonded to said substrate base wafer;

transient liquid phase bonded to said substrate base wafer; and

eutectic bonded to said substrate base wafer.

22. The disc resonator gyroscope of claim 20, wherein said resonator device wafer and said substrate base wafer are each comprised of silicon.