Micro-electro-mechanical gyroscope having electrically insulated regions

• US 7,258,008 B2
• Filed: 12/22/2005
• Issued: 08/21/2007
• Est. Priority Date: 12/29/2004
• Status: Expired due to Fees

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Durante, Guido Spinola, Sassolini, Simone, Clerici, Andrea Rusconi
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US11/317,623
• Publication Number:
  US 20060162448A1
• Time in Patent Office: 607 Days
• Field of Search: 735/040.2, 735/040.4, 735/041.2, 735/041.3, 735/041.4, 735/041.5, 735/041.6
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames

Abstract

An Integrated gyroscope includes a suspended mass; mobile actuation electrodes extending from the suspended mass; and a sensing mass connected to the actuation mass through coupling springs. The suspended mass is formed by an external part and an internal part, electrically separated by an electrical-insulation region having a closed annular shape. The electrical-insulation region is laterally completely surrounded by the external part and by the internal part. In one embodiment, the suspended mass has the shape of a closed frame delimiting an opening, the sensing mass is formed inside the opening and is connected to the internal part, and the mobile actuation electrodes are connected to the external part.

Claims

1. An integrated gyroscope, comprising:

a first suspended mass formed by an external part and an internal part that are electrically separated from each other by an electrical-insulation region having a closed annular shape completely surrounded at sides thereof by said external and internal parts;

first mobile actuation electrodes connected to a first one of said internal and external parts of said suspended mass; and

a first sensing mass connected to a second one of said internal and external parts of said suspended mass.

2. The gyroscope according to claim 1 wherein said first suspended mass has a shape of a closed frame.

3. The gyroscope according to claim 1 wherein said first suspended mass and said first sensing mass are made from a same structural layer.

4. The gyroscope according to claim 1 wherein said first suspended mass is supported through at least first and second anchorage regions, a first anchorage spring extending between and connecting electrically said external part of said first suspended mass and said first anchorage region, and a second anchorage spring extending between and connecting electrically said internal part of said first suspended mass and said second anchorage region.

5. The gyroscope according to claim 4 wherein said first suspended mass delimits an opening, said first anchorage spring and said first anchorage region extend on the outside of said first suspended mass, said second anchorage spring and said second anchorage region extend inside said opening.

6. The gyroscope according to claim 4 wherein said first suspended mass has the shape of a rectangular frame, and said first and second anchorage springs extend approximately from edges of said rectangular frame.

7. The gyroscope according to claim 1, further comprising mobile actuation-feedback electrodes, which face fixed actuation-feedback electrodes, extend from said first suspended mass next to said first mobile actuation electrodes, and are connected to said second one said internal and external parts.

8. The gyroscope according to claim 1 wherein said first suspended mass is mobile in a first direction, and said first sensing mass is carried by said first suspended mass through coupling springs that enable a displacement of said first sensing mass in a second direction transverse to said first direction.

9. The gyroscope according to claim 1 wherein said first suspended mass delimits an opening, said first mobile actuation electrodes extend from said external part of said first suspended mass, and said first sensing mass is accommodated in said opening and is connected to said internal part.

10. The gyroscope according to claim 1, comprising:

a second suspended mass symmetrical to said first suspended mass and having an own external part and an own internal part electrically separated by an own electrical-insulation region having a closed annular shape;

second mobile actuation electrodes connected to said internal part of said second suspended mass; and

wherein said first suspended mass and said second suspended mass each delimit a respective opening, said first sensing mass being connected between said external parts of said first suspended mass and of said second suspended mass, said first mobile actuation electrodes extending inside the opening delimited by the first suspended mass and being connected to the internal part of said first suspended mass, and said second mobile actuation electrodes extending inside the opening delimited by the second suspended mass and being connected to the internal part of said second suspended mass.

11. The gyroscope according to claim 10, comprising:

third and fourth suspended masses formed and positioned substantially symmetrically with said first suspended mass and said second suspended mass;

a first central spring connected between said first suspended mass and said third suspended mass;

a second central spring connected between said second suspended mass and said fourth suspended mass; and

a second sensing mass connected between external parts of said third and fourth suspended masses.

12. The gyroscope according to claim 1, comprising:

a second suspended mass formed and positioned substantially symmetrically with said first suspended mass and including an external part and an internal part that are electrically separated from each other by an electrical-insulation region having a closed annular shape completely surrounded at the sides by said external and internal parts;

central springs connected between said first suspended mass and said second suspended mass;

second mobile actuation electrodes connected to said external part of said second suspended mass; and

a second sensing mass connected to said internal part of said second suspended mass.

23. The gyroscope according to claim 1 wherein the electrical-insulation region includes material selected from among polysilicon, an oxide, a carbide, a nitride, and TEOS.

13. An electrical apparatus comprising:

a gyroscope including;

a first suspended mass formed by an external part and an internal part, which are electrically separated by an electrical-insulation region having a closed annular shape completely surrounded at the sides by said external and internal parts,

mobile actuation electrodes connected to a first one of said internal and external parts of said suspended mass, and

a first sensing mass connected to a second one of said internal and external parts of said first suspended mass;

a signal-processing unit connected to said gyroscope; and

a supply unit connected to said gyroscope and to said processing unit.

14. The electrical apparatus of claim 13 wherein the first suspended mass has a shape of a rectangular frame defining an opening, the apparatus further comprising:

a substrate of semiconductor material;

anchorage springs connected between the first suspended mass and the substrate, and configured to permit movement of the first suspended mass in a first direction relative to the substrate; and

coupling springs connected between the first sensing mass and the first suspended mass such that the first sensing mass is positioned within the opening defined by the first suspended mass and connected to the internal part of the first suspended mass by the coupling springs so as to be movable in a second direction, perpendicular to the first direction, relative to the substrate.

15. The electrical apparatus of claim 13, comprising:

a second suspended mass formed and positioned substantially symmetrically to the first suspended mass, and wherein the first sensing mass is connected between external parts of the first suspended mass and the second suspended mass.

16. A gyroscope comprising:

a suspended mass formed on a substrate of semiconductor material and having an inner part and an outer part concentric to each other and isolated from each other by an insulation region positioned between and concentric with the inner and outer parts such that the inner part and the outer part are rigidly fixed with respect to each other, the suspended mass having a shape of an open frame;

a first plurality of anchor springs, each coupled between the outer part and the substrate; and

a second plurality of anchor springs, each being coupled between the inner part and the substrate, the first and second pluralities of anchor springs configured to permit movement of the suspended mass along a first direction relative to the substrate.

17. The gyroscope of claim 16 wherein at least one of the first plurality of anchor springs comprises an electrical coupling between the outer part and the substrate, and at least one of the second plurality of anchor springs comprises an electrical coupling between the inner part and the substrate.

18. The gyroscope of claim 16, comprising a sensing mass positioned within the open frame shape of the suspended mass and coupled to the suspended mass via a plurality of coupling springs configured to permit movement of the sensing mass along a second direction relative to the substrate.

20. The gyroscope of claim 16 wherein the open frame shaped suspended mass is in a form selected from among a polygon, an oval, and a circle.

21. The gyroscope of claim 18, comprising:

a plurality of actuation electrodes mechanically and electrically coupled to the outer part; and

a plurality of sensing electrodes mechanically coupled to the sensing mass and electrically coupled to the inner part, via the sensing mass and the plurality of coupling springs.

19. A gyroscope comprising:

a suspended mass formed on a substrate of semiconductor material and having an inner part and an outer part concentric to each other and isolated from each other by an insulation region positioned between and concentric with the inner and outer parts such that the inner part and the outer part are rigidly fixed with respect to each other, the suspended mass having a shape of an open frame;

a first plurality of anchor springs, each coupled between the outer part and the substrate;

a second plurality of anchor springs, each being coupled between the inner part and the substrate, the first and second pluralities of anchor springs configured to permit movement of the suspended mass along a first direction relative to the substrate; and

a sensing mass coupled between the suspended mass and a second suspended mass via a plurality of coupling springs configured to permit movement of the sensing mass along a second direction relative to the substrate.

22. The gyroscope of claim 19, comprising:

a plurality of actuation electrodes mechanically and electrically coupled to the inner part; and

a plurality of sensing electrodes mechanically coupled to the sensing mass and electrically coupled to the outer part, via the sensing mass and the plurality of coupling springs.