UNIAXIAL OR BIAXIAL MICROELECTROMECHANICAL GYROSCOPE WITH IMPROVED SENSITIVITY TO ANGULAR VELOCITY DETECTION

• US 20100126272A1
• Filed: 11/25/2009
• Published: 05/27/2010
• 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
• Granted Patent: US 8,312,769 B2
• Time in Patent Office: Days
• US Class Current: 73/504.140
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An integrated microelectromechanical structure is provided with: a driving mass, anchored to a substrate via elastic anchorage elements and moved in a plane with a driving movement; and a first sensing mass, suspended inside, and coupled to, the driving mass via elastic supporting elements so as to be fixed with respect to the driving mass in the driving movement and to perform a detection movement of rotation out of the plane in response to a first angular velocity; the elastic anchorage elements and the elastic supporting elements cause the detection movement to be decoupled from the driving movement. The elastic supporting elements are coupled to the first sensing mass at an end portion thereof, and the axis of rotation of the detection movement extends, within the first sensing mass, only through the end portion.

Claims

1. An integrated microelectromechanical structure, comprising:

a substrate;

elastic anchorage elements fixed to the substrate;

a driving mass anchored to the substrate via the elastic anchorage elements, and designed to be moved in a plane with a driving movement;

elastic supporting elements; and

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

wherein said elastic supporting elements are coupled to said first sensing mass at an end portion of the first sensing mass in an arrangement in which an axis of rotation of said detection movement extends, inside said first sensing mass, only through said end portion.

2. The structure according to claim 1 wherein said driving movement is a rotation about a transverse axis that is transverse to the plane, and said driving mass has inside it a through opening;

and wherein said first sensing mass is in said through opening, and said elastic supporting elements extend inside said through opening between said driving mass and said end portion;

said elastic anchorage elements and said elastic supporting elements being configured so that said driving mass is decoupled from said first sensing mass during said detection movement.

3. The structure according to claim 1, further comprising a single sensing electrode forming a sensing capacitor with the first sensing mass;

said sensing electrode being on said substrate and underneath said first sensing mass.

4. The structure according to claim 3 wherein said first sensing mass extends in cantilever fashion from said elastic supporting elements, and has a main body entirely on one side of said axis of rotation;

and wherein said sensing electrode is underneath said main body.

5. The structure according to claim 4 wherein said sensing electrode has dimensions substantially coinciding with dimensions of said main body.

6. The structure according to claim 1, comprising a second sensing mass operatively coupled to said first sensing mass, and forming therewith a first pair of sensing masses, aligned in a first direction of said plane;

wherein a respective end portions of said first and second sensing masses correspond to a radially more internal sides of said first and second sensing masses, respectively, with respect to a center of rotation of said driving mass.

7. The structure according to claim 6 wherein said elastic supporting elements define said axis of rotation of said detection movement;

and wherein said first and second sensing masses of said first pair extend in cantilever fashion from the respective elastic supporting elements, and are positioned on opposite sides of said elastic supporting elements along said first direction.

8. The structure according to claim 6, of a biaxial type, further comprising:

further elastic supporting elements; and

a second pair of sensing masses, suspended inside, and respectively coupled to, said driving mass via the further elastic supporting elements, and aligned in a second direction;

said further elastic supporting elements being respectively coupled to respective end portions of said sensing masses of said second pair so that axes of rotation of respective detection movements extend, inside said sensing masses of said second pair, only through said respective end portions.

9. The structure according to claim 8, further comprising a die, including the substrate and a frame defining a sensing region and having a first side extending along a first axis of the plane;

wherein said first direction and second direction have non-zero inclinations of opposite signs with respect to said first axis.

10. The structure according to claim 9 wherein said first direction is inclined with respect to said first axis by an angle, and said second direction is inclined by the same angle, on the opposite side with respect to said first axis.

11. The structure according to claim 10 wherein said angle has a value substantially equal to 45°

.

12. The structure according to claim 9, further comprising a plurality of die pads extending along said first side of said frame in a symmetrical way with respect to a second axis of the plane;

wherein each of said sensing masses of said first pair is set symmetrically to a corresponding one of said sensing masses of said second pair with respect to said second axis.

13. The structure according to claim 9 wherein said rotation of the structure at the first angular velocity is applied in use about said first axis, coinciding with a first axis of detection of said structure.

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

a first anchorage set substantially 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 on the 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 so that said driving mass is decoupled from said first sensing mass in said detection movement of rotation out of said plane.

15. The structure according to claim 1 wherein said first sensing mass has radial sector shapes.

16. An electronic device comprising:

an integrated microelectromechanical structure , that includes;

a substrate;

elastic anchorage elements fixed to the substrate;

a driving mass anchored to the substrate via the elastic anchorage elements, and designed to be moved in a plane with a driving movement;

elastic supporting elements; and

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

wherein said elastic supporting elements are coupled to said first sensing mass at an end portion of the first sensing mass in an arrangement in which an axis of rotation of said detection movement extends, inside said first sensing mass, only through said end portion; and

a read stage, operatively coupled to said integrated microelectromechanical structure.

17. The electronic device of claim 16 wherein said driving movement is a rotation about a transverse axis that is transverse to the plane, and said driving mass has inside it a through opening;

and wherein said first sensing mass is in said through opening, and said elastic supporting elements extend inside said through opening between said driving mass and said end portion;

said elastic anchorage elements and said elastic supporting elements being configured so that said driving mass is decoupled from said first sensing mass during said detection movement.

18. The electronic device of claim 16, further comprising a single sensing electrode forming a sensing capacitor with the first sensing mass;

said sensing electrode being on said substrate and underneath said first sensing mass.

19. The electronic device of claim 18 wherein said first sensing mass extends in cantilever fashion from said elastic supporting elements, and has a main body entirely on one side of said axis of rotation;

and wherein said sensing electrode is underneath said main body.

20. The electronic device of claim 19 wherein said sensing electrode has dimensions substantially coinciding with dimensions of said main body.

21. The electronic device of claim 16, comprising a second sensing mass operatively coupled to said first sensing mass, and forming therewith a first pair of sensing masses, aligned in a first direction of said plane;

wherein a respective end portions of said first and second sensing masses correspond to a radially more internal sides of said first and second sensing masses, respectively, with respect to a center of rotation of said driving mass.

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

forming a substrate;

forming elastic anchorage elements configured to be fixed to the substrate;

anchoring a driving mass to a substrate via the elastic anchorage elements, the driving mass being configured to move in a plane with a driving movement;

forming elastic supporting elements;

suspending a first sensing mass inside the driving mass; and

coupling the first sensing mass to the driving mass via the elastic supporting elements configured to be fixed with respect to the driving mass in the driving movement and to perform a detection movement of rotation out of the plane, in response to a rotation of the structure at a first angular velocity;

wherein the elastic supporting elements are coupled to the first sensing mass at an end portion of the first sensing mass in an arrangement in which an axis of rotation of the detection movement extends, inside the first sensing mass, only through the end portion.

23. The method of claim 22, further comprising:

forming a through opening in the driving mass, wherein the first sensing mass is in the through opening, and the elastic supporting elements extend inside the through opening between the driving mass and the end portion;

the elastic anchorage elements and the elastic supporting elements being configured so that the driving mass is decoupled from the first sensing mass during the detection movement, and wherein the driving movement is a rotation about a transverse axis that is transverse to the plane.

24. The method of claim 22, further comprising

forming a sensing capacitor with the first sensing mass by coupling a single sensing electrode to the first sensing mass, the sensing electrode being on the substrate and underneath the first sensing mass.

25. The method of claim 24 wherein the first sensing mass extends in cantilever fashion from the elastic supporting elements, and has a main body entirely on one side of the axis of rotation;

and wherein the sensing electrode is underneath the main body.

26. The method of claim 25 wherein the sensing electrode has dimensions substantially corresponding with dimensions of the main body.

27. The method of claim 22, further comprising:

forming a second sensing mass operatively coupled to the first sensing mass, wherein the first and second sensing masses form a first pair of sensing masses, aligned in a first direction of the plane and respective end portions of the first and second sensing masses correspond to radially more internal sides of the first and second sensing masses, respectively, with respect to a center of rotation of the driving mass.