Microelectromechanical gyroscope with rotary driving motion and improved electrical properties

• US 8,413,506 B2
• Filed: 11/25/2009
• Issued: 04/09/2013
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Coronato, Luca, Cazzaniga, Gabriele, Zerbini, Sarah
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/626,433
• Publication Number:
  US 20100126269A1
• Time in Patent Office: 1,231 Days
• Field of Search: 735/041.2, 735/041.4
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

An integrated microelectromechanical structure is provided with: a die, having a substrate and a frame, defining inside it a detection region and having a first side extending along a first axis; a driving mass, anchored to the substrate, set in the detection region, and designed to be rotated in a plane with a movement of actuation about a vertical axis; and a first pair and a second pair of first sensing masses, suspended inside the driving mass via elastic supporting elements so as to be fixed with respect thereto in the movement of actuation and so as to perform a detection movement of rotation out of the plane in response to a first angular velocity; wherein the first sensing masses of the first pair and the first sensing masses of the second pair are aligned in respective directions, having non-zero inclinations of opposite sign with respect to the first axis.

Claims

1. An integrated microelectromechanical structure, comprising:

a die including a substrate and a frame, the frame defining a detection region and having a first side extending along a first axis of a plane that includes a second axis;

elastic anchorage elements;

a driving mass anchored to said substrate via the elastic anchorage elements, set in said detection region, and configured to be rotated in the plane with a movement of actuation about a third axis transverse to the plane;

elastic supporting elements; and

a first pair and a second pair of first sensing masses, suspended inside, and respectively coupled to, said driving mass, via the elastic supporting elements so as to be fixed with respect to the driving mass in said movement of actuation and perform a detection movement of rotation out of said plane in response to a rotation of the structure at a first angular velocity;

said first pair and said second pair being aligned in respective directions having non-zero inclinations of opposite sign with respect to said first axis.

2. The structure according to claim 1 wherein said first sensing masses of said first pair are aligned in a first direction inclined with respect to said first axis by an angle, and said first sensing masses of said second pair are aligned in a second direction inclined by the same angle, on an opposite side with respect to said first axis.

3. The structure according to claim 2 wherein said angle has a value substantially equal to 45°

.

4. The structure according claim 1, further comprising a plurality of die pads extending along said first side of said frame in a symmetrical way with respect to the second axis;

wherein each of said first sensing masses of said first pair is arranged symmetrically to a corresponding one of said first sensing masses of said second pair and on opposites sides of said second axis.

5. The structure according to claim 4, further comprising:

a plurality of pairs of sensing electrodes associated respectively with the sensing masses of the first and second pairs, each pair of sensing electrodes being configured to form a respective one of a plurality of sensing capacitors; and

electrical connections between said respective sensing electrodes and respective ones of said die pads;

wherein the electrical connections for the respective sensing electrodes associated with said first sensing masses of said first pair are set symmetrically to the electrical connections for the respective sensing electrodes associated with said first sensing masses of said second pair, with respect to said second axis.

6. The structure according to claim 1 wherein said frame has a second side extending along the second axis and defining an edge with said first side;

wherein at least one first sensing mass of said first and second pairs is shaped to have an end that corresponds to the edge of the frame, along a respective one of said first direction and said second direction.

7. The structure according to claim 6 wherein said at least one first sensing mass has a generally rhomboidal shape, elongated along said respective one of said first direction and said second direction.

8. The structure according to claim 1 wherein said rotation of the structure at said first angular velocity is about said first axis, which is configured to coincide with a first axis of detection of said structure.

9. The structure according to claim 8, of a biaxial type, wherein said first sensing masses of said first pair and second pair are also designed to perform said detection movement of rotation out of said plane in response to a rotation of the structure at a second angular velocity, applied in use about the second axis, orthogonal to said first axis and coinciding with a second axis of detection of said structure.

10. The structure according to claim 9, of a triaxial type, further comprising:

elastic supporting element; and

a pair of second sensing masses, suspended inside, and respectively coupled to, said driving mass via the elastic supporting elements so as to be fixed with respect to the driving mass in said movement of actuation and so as to perform a linear movement of detection in said plane in response to a rotation of the structure at a third angular velocity about said third axis;

wherein said second sensing masses are aligned along one of said first axis and second axis.

11. The structure according to claim 1 wherein said frame has a generally square or rectangular shape, with first sides parallel to said first axis and second sides parallel to the second axis, orthogonal to said first axis.

12. The structure according to claim 1 wherein said driving mass defines a central empty space, the structure further comprising:

a first anchorage set at a center of said empty space and fixed to the substrate;

first elastic anchorage elements extending inside said empty space and between the driving mass and the first anchorage;

a plurality of second anchorages set outside of said driving mass and fixed to the substrate; and

second elastic anchorage elements extending between the driving mass and the second anchorages, respectively;

wherein said elastic supporting elements and said first and second elastic anchorage elements are configured in such a way that said driving mass is decoupled from said first sensing masses in said detection movement of rotation out of said plane.

13. The structure according to claim 1 wherein said first sensing masses have radial sector shapes.

14. An electronic device comprising:

an integrated microelectromechanical structure, further comprising;

a die including a substrate and a frame, the frame defining a detection region and having a first side extending along a first axis of a plane that includes a second axis;

elastic anchorage elements;

a driving mass anchored to said substrate via the elastic anchorage elements, set in said detection region, and configured to be rotated in the plane with a movement of actuation about a third axis transverse to the plane;

elastic supporting elements; and

a first pair and a second pair of first sensing masses, suspended inside, and respectively coupled to, said driving mass, via the elastic supporting elements so as to be fixed with respect to the driving mass in said movement of actuation and perform a detection movement of rotation out of said plane in response to a rotation of the structure at a first angular velocity;

said first pair and said second pair being aligned in respective directions having non-zero inclinations of opposite sign with respect to said first axis; and

a read stage, operatively coupled to said structure.

15. The electronic device according to claim 14, further comprising a central processing unit and a driving circuit coupled to the structure.

16. The electronic device according to claim 14 wherein said first sensing masses of said first pair are aligned in a first direction inclined with respect to said first axis by an angle, and said first sensing masses of said second pair are aligned in a second direction inclined by the same angle, on an opposite side with respect to said first axis.

17. The electronic device according to claim 16 wherein said angle has a value substantially equal to 45.

18. The electronic device according to claim 14 wherein the structure includes a plurality of die pads extending along said first side of said frame in a symmetrical way with respect to the second axis;

wherein said first sensing masses of said first pair are arranged symmetrically to a corresponding one of said first sensing masses of said second pair and on opposite sides of said second axis.

19. The electronic sensing device according to claim 18 wherein said read stage is connected to said die pads for receiving electrical signals from each of said first sensing masses, and is configured to combine said electrical signals and generate a first electrical output quantity and a second electrical output quantity, which are a function, respectively, of the first angular velocity applied about said first axis and a second angular velocity applied about the second axis, orthogonal to said first axis.

20. A method of forming an integrated microelectromechanical structure, comprising:

forming a die having a substrate and a frame having a first side extending along a first axis of a plane that includes a second axis;

forming a detection region in the frame;

forming elastic anchorage elements;

anchoring a driving mass to the substrate via the elastic anchorage elements in the detection region, the driving mass configured to be rotated in a plane with a movement of actuation about a third axis transverse to the plane;

forming elastic supporting elements; and

forming a first pair and a second pair of first sensing masses, suspended inside, and respectively coupled to, the driving mass via the elastic supporting elements so as to be fixed with respect to the driving mass in the movement of actuation and perform a detection movement of rotation out of the plane in response to a rotation of the structure at a first angular velocity;

the first pair and the second pair being aligned in respective directions having non-zero inclinations of opposite sign with respect to the first axis.

21. The method of claim 20, further comprising:

aligning the first sensing masses of the first pair in a first direction inclined with respect to the first axis by an angle; and

aligning the first sensing masses of the second pair in a second direction inclined by the same angle, on an opposite side with respect to the first axis.

22. The method of claim 21 wherein the angle has a value substantially equal to 45.

23. The method of claim 20, further comprising:

forming a plurality of die pads along the first side of the frame in a symmetrical way with respect to the second axis;

wherein the first sensing masses of the first pair are arranged symmetrically to a corresponding one of the first sensing masses of the second pair and on an opposite side the second axis.