Microelectromechanical gyroscope with enhanced rejection of acceleration noises

• US 8,347,716 B2
• Filed: 12/17/2009
• Issued: 01/08/2013
• Est. Priority Date: 12/23/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Cazzaniga, Gabriele, Coronato, Luca, Calcaterra, Giacomo
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/641,106
• Publication Number:
  US 20100154541A1
• Time in Patent Office: 1,118 Days
• Field of Search: 735/041.2, 735/041.4
• US Class Current: 73/504.12
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• 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 designed to be actuated in a plane with a driving movement; and a first sensing mass and a second sensing mass, suspended within, and coupled to, the driving mass via respective elastic supporting elements so as to be fixed with respect thereto in said driving movement and to perform a respective detection movement in response to an angular velocity. In particular, the first and the second sensing masses are connected together via elastic coupling elements, configured to couple their modes of vibration.

Claims

1. An integrated microelectromechanical structure, comprising:

a substrate;

a driving mass configured to be actuated in a plane with a driving movement;

first and second elastic anchorage elements anchoring the driving mass to the substrate;

first and second elastic supporting elements;

a first sensing mass and a second sensing mass suspended within said driving mass and respectively coupled to the driving mass via the first and second elastic supporting elements, respectively, the sensing masses being configured to move with said driving mass in said driving movement and being configured to perform respective detection movements in response to an angular movement of the driving mass; and

elastic coupling elements coupling the sensing masses to each other and configured to couple modes of vibration of the sensing masses.

2. The structure according to claim 1, wherein said driving mass is configured to be actuated with a rotary movement in said plane, and said first and second sensing masses are configured to perform the respective linear detection movement in said plane in response to said angular movement;

the detection movements of said first and second sensing masses being in phase opposition with respect to one another and in a radial direction.

3. The structure according to claim 1, wherein the elastic coupling elements include first and second elastic coupling elements respectively associated with said first and second sensing masses, the structure comprising:

a connection body having a substantially negligible mass and coupling the first and second elastic coupling elements to each other.

4. The structure according to claim 3, comprising further elastic supporting elements connected between said connection body and said driving mass.

5. The structure according to claim 3 wherein said driving mass includes a through opening;

said first and second sensing masses, said elastic coupling elements, said further elastic supporting elements and said connection body being arranged within said through opening.

6. The structure according to claim 1 wherein said elastic coupling elements are configured in such a way that said first sensing mass and second sensing mass have two vibration modes, one in phase and the other in phase opposition, having frequencies that are distinct from one another.

7. The structure according to claim 1, wherein said driving mass is configured to be actuated with a rotary movement in said plane, the structure including:

a first sensing capacitor having;

a first mobile electrode fixedly connected to said first sensing mass, and

a first fixed electrode facing said first mobile electrode; and

a second sensing capacitor having;

a second mobile electrode fixedly connected to said second sensing mass, and

a second fixed electrode facing said second mobile electrode.

8. The structure according to claim 7, wherein said first mobile electrode and first fixed electrode have respective faces facing each other, the faces sharing a common shaped profile configured such that a first capacitive variation, generated in said first sensing capacitor by the angular movement of the sensing mass, compensates for a second capacitive variation generated in said first sensing capacitor by a centrifugal acceleration deriving from said driving movement.

9. The structure according to claim 7, wherein the first fixed electrode has a surface that faces a first surface of the first mobile electrode and the structure includes a third fixed electrode fixed to the first second mass and having a surface that faces a second surface of said mobile electrodes, the first and second surfaces being on opposite sides with respect to a radial direction;

the surface one of the first fixed electrode having a shaped profile that matches the first surface of said first mobile electrode.

10. The structure according to claim 9, wherein said shaped profile is a substantially sinusoidal profile.

11. The structure according to claim 7, wherein said first and second sensing masses include first and second windows, respective, said first mobile electrode and said first fixed electrode being positioned in the first window and said second mobile electrode and said second fixed electrode being positioned in the second window;

said first and second mobile electrodes extending from internal walls of said first sensing mass and second sensing mass, respectively.

12. The structure according to claim 1 wherein said angular movement is a yaw angular movement about a vertical axis transverse to said plane.

13. The structure according to claim 1 comprising a first pair and a second pair of further sensing masses, suspended within, and coupled to, said driving mass via respective elastic elements so as to be fixed with respect to the driving mass in said driving movement and to perform a detection movement of rotation out of said plane in response to a first further angular velocity and a second further angular velocity acting, respectively, about a first axis and a second axis that are transverse and belong to said plane;

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

14. An electronic device comprising:

an integrated microelectromechanical structure that includes;

a substrate;

a driving mass configured to be actuated in a plane with a driving movement;

first and second elastic anchorage elements anchoring the driving mass to the substrate;

first and second elastic supporting elements;

a first sensing mass and a second sensing mass suspended within said driving mass and respectively coupled to the driving mass via the first and second elastic supporting elements, respectively, the sensing masses being configured to move with said driving mass in said driving movement and being configured to perform respective detection movements in response to an angular movement of the driving mass; and

elastic coupling elements coupling the sensing masses to each other and configured to couple modes of vibration of the sensing masses; and

a reading stage operatively coupled to said integrated microelectromechanical structure.

15. The device according to claim 14, wherein said elastic coupling elements are configured in such a way that said first and second sensing masses have two vibration modes, one in phase and the other in phase opposition, having frequencies that are distinct from one another;

and wherein said reading stage is configured so as to eliminate a contribution of said in-phase vibration mode.

16. The device according to claim 14, wherein the structure includes a first sensing capacitor and a second sensing capacitor, the first sensing capacitor including a mobile electrode and a first fixed electrode positioned on a first side of the mobile electrode, the second sensing capacitor including the mobile electrode and a second fixed electrode positioned on a second side of the mobile electrode, the first and second sides being opposite sides with respect to a radial direction;

wherein said reading stage is configured to process a capacitive difference between said first and second sensing capacitors.

17. A method, comprising:

forming an integrated micromechanical structure, the forming including;

forming a driving mass configured to be actuated in a plane with a driving movement;

forming first and second elastic anchorage elements anchoring the driving mass to a substrate;

forming first and second elastic supporting elements;

forming a first sensing mass and a second sensing mass suspended within said driving mass and respectively coupled to the driving mass via the first and second elastic supporting elements, respectively, the sensing masses being configured to move with said driving mass in said driving movement and being configured to perform respective detection movements in response to an angular movement of the driving mass; and

forming elastic coupling elements coupling the sensing masses to each other and configured to couple modes of vibration of the sensing masses.

18. The method of claim 17, wherein said driving mass is configured to be actuated with a rotary movement in said plane, and said first and second sensing masses are configured to perform the respective linear detection movement in said plane in response to said angular movement;

the detection movements of said first and second sensing masses being in phase opposition with respect to one another and in a radial direction.

19. The method according to claim 17, wherein forming the elastic coupling elements includes forming first and second elastic coupling elements respectively associated with said first and second sensing masses, the method further comprising:

forming a connection body having a substantially negligible mass and coupling the first and second elastic coupling elements to each other.

20. The method according to claim 19, comprising forming further elastic supporting elements connected between said connection body and said driving mass.