MEMS multi-axis gyroscope with central suspension and gimbal structure

• US 8,813,564 B2
• Filed: 01/31/2013
• Issued: 08/26/2014
• Est. Priority Date: 09/18/2010
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Acar, Cenk
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US13/755,841
• Publication Number:
  US 20130139591A1
• Time in Patent Office: 572 Days
• Field of Search: 735/041.2, 735/041.4, 735/040.4, 735/040.2
• US Class Current: 73/504.12
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/0154 Torsion bars
• 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: B81B 3/0059 Constitution or structural means for controlling the movement not provided for in groups B81B3/0037 - B81B3/0056
• CPC Class Codes: B81C 1/00134 comprising flexible or deformable structures manufacture of MEMS devices for specific applications, see relevant places, e.g. gyroscopes G01C19/5719, pressure sensors G01L9/0042, accelerometers G01P15/0802, acoustic transducers or diaphragms therefor H04R31/00
• 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

Abstract

Various examples include microelectromechanical die for sensing motion that includes symmetrical proof-mass electrodes interdigitated with asymmetrical stator electrodes. Some of these examples include electrodes that are curved around an axis orthogonal to the plane in which the electrodes are disposed. An example provides vertical flexures coupling an inner gimbal to a proof-mass in a manner permitting flexure around a horizontal axis.

Claims

1. A microelectromechanical die for sensing motion, comprising:

a fixed portion;

an anchor coupled to the fixed portion;

a first nonlinear suspension member coupled to anchor on a first side of the anchor;

a second nonlinear suspension member coupled to the anchor on the first side of the anchor, the second nonlinear suspension member having a shape and location mirroring the first nonlinear suspension member about an anchor bisecting plane, wherein the first nonlinear suspension member and the second nonlinear suspension member are part of an inner gimbal of the microelectromechanical die; and

a proof-mass that is planar, the proof-mass suspended by a first suspension member disposed on a first side of the anchor and a second suspension member disposed on a second side of the anchor opposite the first side, with the die defining a first gap extending along a first side of the anchor and a second gap extending along a second side of the anchor, opposite the first side, with each of the first gap and the second gap extending between the inner gimbal and the proof-mass,

wherein the inner gimbal is supported at least in part by the first nonlinear suspension member and the second nonlinear suspension member such that the proof-mass is rotatable about the anchor and is slideable in a plane parallel to the fixed portion.

2. The die of claim 1, wherein the first gap extends from the first suspension member to the second suspension member, and the second gap extends from the first suspension member to the second suspension member.

3. The die of claim 1, wherein the first gap and the second gap are C-shaped, with a first C-shape defining a first opening that opens to a second opening of a second C-shape.

4. The die of claim 3, wherein the first gap defines a first vertical flexure and a second vertical flexure, and the second gap defines a third vertical flexure and a fourth vertical flexure.

5. The die of claim 4, wherein each of the first, second, third and fourth vertical flexures are elongate, with a length longer than a width, with each respective length extending away from a respective suspension member.

6. The die of claim 5, wherein each respective length extends away from the anchor bisecting plane.

7. The die of claim 3, wherein the first C-shape includes a first end portion and a second end portion, with a center portion extending between the first end portion and the second end portion.

8. The die of claim 7, wherein the first end portion and the second end portion are perpendicular to the center portion.

9. The die of claim 7, wherein a first canted portion extends between the first end portion and the center portion and a second canted portion extends between the second end portion and the center portion.

10. The die of claim 1, wherein the first gap is a mirrored shape of the second gap and the first gap is mirrored along the anchor bisecting plane.

11. A method for sensing motion with a microelectromechanical die, comprising:

rotating a proof-mass with respect to an inner gimbal that is coupled to a substrate via an anchor, by;

deforming a first nonlinear suspension member, that couples the proof-mass to a first side of the anchor, out-of-plane of the plane of the proof-mass, above the proof-mass; and

deforming a second nonlinear suspension member, that couples the proof-mass to the first side of the anchor, out-of-plane of the plane of the proof-mass on an opposite first side of the plane of the proof-mass, below the proof-mass; and

deforming a first suspension member, that supports the proof-mass and that is disposed on a first side of the anchor, and a second suspension member, that is disposed on a second side of the anchor opposite the first side, with the die defining a first gap extending along a first side of the anchor and a second gap extending along a second side of the anchor, opposite the first side, with each of the first gap and the second gap extending between the inner gimbal and the proof-mass.

12. The method of claim 11, wherein deforming a first suspension member, that supports the proof-mass and that is disposed on a first side of the anchor, and a second suspension member, that is disposed on a second side of the anchor opposite the first side includes deforming a first vertical flexure and a second vertical flexure, each defined by the first gap, and a third vertical flexure and a fourth vertical flexure, each defined by the second gap.

13. The method of claim 12, wherein during a first half of a rotation cycle, the first and second vertical flexures are deformed away from the anchor, and the third and fourth vertical flexure are deformed toward the anchor, and during a second half of a rotation cycle, the first and second vertical flexures are deformed toward from the anchor, and the third and fourth vertical flexure are deformed away the anchor.

14. The method of claim 13, wherein deforming of the flexures includes bending.

15. The method of claim 12, wherein an anchor bisecting plane bisects the anchor vertically and passes between the first and second nonlinear suspension members, between the first and second suspension members.