Vibration and shock robust gyroscope

• US 10,126,129 B2
• Filed: 07/11/2016
• Issued: 11/13/2018
• Est. Priority Date: 07/11/2016
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Inventors: Naumann, Michael
• Primary Examiner(s): Macchiarolo, Peter J
• Assistant Examiner(s): Mercado, Alexander A
• Application Number:
  US15/207,229
• Publication Number:
  US 20180010913A1
• Time in Patent Office: 855 Days
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/0163 Spring holders
• CPC Class Codes: B81B 7/0016 Protection against shocks or vibrations, e.g. vibration damping
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A MEMS device includes a movable mass having a central region overlying a sense electrode and an opening in which a suspension structure and spring system are located. The suspension structure includes an anchor coupled to a substrate and rigid links extending from opposing sides of the anchor. The spring system includes a first and second spring heads coupled to each of the rigid links. A first drive spring is coupled to the first spring head and to the movable mass, and a second drive spring is coupled to the second spring head and to the movable mass. The movable mass is resiliently suspended above the surface of the substrate via the suspension structure and the spring system. The spring system enables drive motion of the movable mass in the drive direction and sense motion of the movable mass in a sense direction perpendicular to the surface of the substrate.

Claims

1. A microelectromechanical systems (MEMS) device comprising:

a substrate;

a movable mass having an end region laterally displaced away from a central region of said movable mass, wherein an opening extends through said end region;

a suspension structure located in said opening, said suspension structure including an anchor coupled to a surface of said substrate, a first rigid link coupled to and extending from a first side of said anchor, and a second rigid link coupled to and extending from a second side of said anchor, each of said first and second rigid links having a lengthwise dimension oriented perpendicular to a drive direction of said movable mass, said drive direction being substantially parallel to said surface of said substrate; and

a spring system located in said opening, said spring system including;

a first spring head coupled to a first end of said first rigid link;

a second spring head coupled a second end of said second rigid link;

a first drive spring coupled to said first spring head and coupled to said movable mass; and

a second drive spring coupled to said second spring head and coupled to said movable mass, wherein said movable mass is resiliently suspended above said surface of said substrate via said suspension structure and said spring system, said spring system enables drive motion of said movable mass in said drive direction and enables sense motion of said movable mass in a sense direction that is perpendicular to said surface of said substrate.

2. The MEMS device of claim 1 wherein said movable mass in characterized by a midline that is substantially parallel to said drive direction, said anchor is located at said midline of said movable mass, said first and second rigid links are arranged on opposing sides of said midline, and said first spring head and said first drive spring are arranged in mirror symmetry with said second spring head and said second drive spring relative to said midline.

3. The MEMS device of claim 1 wherein each of said first and second spring heads comprises a torsion beam configured to enable rotation about an axis oriented substantially parallel to said drive direction.

4. The MEMS device of claim 3 wherein said torsion beam comprises:

a first torsion beam section aligned with said axis;

a second torsion beam section aligned with said axis, said first and second torsion beam sections having a first beam end coupled to and extending from opposing lengthwise edges of a respective one of said first and second rigid links; and

a connection bar aligned with said axis and interconnecting a second beam end of each of said first and second torsion beam sections.

5. The MEMS device of claim 1 wherein said spring system further comprises a connection spring connecting said first drive spring with said second drive spring.

6. The MEMS device of claim 1 wherein said end region is a first end region, said opening is a first opening, said suspension structure is a first suspension structure, said spring system is a first spring system, and:

said movable mass has a second end region laterally displaced away from said first end region with said central region interposed between said first and second end regions, wherein a second opening extends through said second end region; and

said MEMS device further comprises;

a second suspension structure located in said second opening, said second suspension structure including a second anchor coupled to said surface of said substrate, a third rigid link coupled to and extending from a third side of said second anchor, and a fourth rigid link coupled to and extending from a fourth side of said second anchor, each of said third and fourth rigid links having said lengthwise dimension oriented perpendicular to said drive direction of said movable mass; and

a second spring system located in said second opening, said second spring system including a third spring head coupled to a third end of said third rigid link, a fourth spring head coupled a fourth end of said fourth rigid link, a third drive spring coupled to said third spring head and coupled to said movable mass, a fourth drive spring coupled to said fourth spring head and coupled to said movable mass.

7. The MEMS device of claim 6 wherein said movable mass is characterized by a midline that is substantially parallel to said surface of said substrate and perpendicular to said drive direction, and wherein said second suspension structure and said second spring system are arranged in mirror symmetry with said first suspension structure and said first spring system.

8. The MEMS device of claim 6 wherein said movable mass is characterized by a midline that is substantially parallel to said drive direction, each of said first and second anchors is located at said midline of said movable mass, said first and second rigid links are arranged on opposing sides of said midline, said first spring head and said first drive spring are arranged in mirror symmetry with said second spring head and said second drive spring relative to said midline, said third and fourth rigid links are arranged on said opposing sides of said midline, and said third spring head and said third drive spring are arranged in mirror symmetry with said fourth spring head and said fourth drive spring relative to said midline.

9. The MEMS device of claim 1 further comprising a sense electrode formed on said surface of said substrate underlying said central region of said movable mass.

10. The MEMS device of claim 1 wherein said movable mass is a first movable mass, and said MEMS device further comprises:

a second movable mass resiliently suspended above said surface of said substrate adjacent to said first movable mass;

a couple spring structure having a stiff beam coupled to said surface of said substrate via a beam anchor, said couple spring structure interconnecting said first movable mass with said second movable mass, a second lengthwise dimension of said stiff beam being oriented perpendicular to said drive direction, said couple spring structure being configured to pivot about an axis that is substantially perpendicular to said surface of said substrate in response to said drive motion of said first and second movable masses.

11. The MEMS device of claim 10 wherein said couple spring structure further comprises:

a first elastic element coupled between a first beam end of said stiff beam and said first movable mass; and

a second elastic element coupled between a second beam end of said stiff beam and said second movable mass, said first and second elastic elements being oriented transverse to said stiff beam, said first and second elastic elements functioning cooperatively with said stiff beam to enable said first and second movable masses to move in phase opposition with one another in response to said drive motion.

12. The MEMS device of claim 10 wherein said couple spring structure further comprises a torsion member interconnected between said stiff beam and said beam anchor, said torsion member enabling teeter totter motion of said stiff beam about an axis aligned with said torsion member in response to said sense motion of said first and second movable masses.

13. The MEMS device of claim 12 wherein said torsion member is configured to enable parallel plate motion of first and said movable masses in phase opposition with one another in response to said sense motion.

14. The MEMS device of claim 10 wherein:

said first movable mass has a second end region laterally displaced away from said first end region with said central region interposed between said first and second end regions;

said second movable mass has a third end region laterally displaced away from a fourth end region with a second central region interposed between said third and fourth end regions;

said couple spring structure is a first couple spring structure coupled to each of said first and third end regions of respective first and second movable masses; and

said MEMS device further comprises a second couple spring structure having a second stiff beam coupled to said surface of said substrate via a second beam anchor, said second couple spring structure interconnecting said second end of said first movable mass with said fourth end of said second movable mass, said second couple spring structure being configured to pivot about a second axis that is substantially perpendicular to said surface of said substrate in response to said drive motion of said first and second movable masses.

17. The MEMS device of claim 1 wherein:

said first spring system further comprises a first connection spring connecting said first drive spring with said second drive spring; and

said second spring system further comprises a second connection spring connecting said third drive spring with said fourth drive spring.

20. The MEMS device of claim 10 wherein:

said couple spring structure is a first couple spring structure coupled to each of said first and third end regions of respective first and second movable masses; and

said MEMS device further comprises a second couple spring structure having a second stiff beam coupled to said surface of said substrate via a second beam anchor, said second couple spring structure interconnecting said second end of said first movable mass with said fourth end of said second movable mass, said second couple spring structure being configured to pivot about a second axis that is substantially perpendicular to said surface of said substrate in response to said drive motion of said first and second movable masses.

15. A microelectromechanical systems (MEMS) device comprising:

a substrate;

a movable mass having a first end region laterally displaced away from a second end region with a central region interposed between said first and second end regions, wherein a first opening extends through said first end region and a second opening extends through said second end region;

a first suspension structure located in said first opening, said first suspension structure including a first anchor coupled to a surface of said substrate, a first rigid link coupled to and extending from a first side of said first anchor, and a second rigid link coupled to and extending from a second side of said first anchor, each of said first and second rigid links having a lengthwise dimension oriented perpendicular to a drive direction of said movable mass, said drive direction being substantially parallel to said surface of said substrate;

a first spring system located in said first opening, said first spring system including a first spring head coupled to a first end of said first rigid link, a second spring head coupled a second end of said second rigid link, a first drive spring coupled to said first spring head and coupled to said movable mass, and a second drive spring coupled to said second spring head and coupled to said movable mass;

a second suspension structure located in said second opening, said second suspension structure including a second anchor coupled to said surface of said substrate, a third rigid link coupled to and extending from a third side of said second anchor, and a fourth rigid link coupled to and extending from a fourth side of said second anchor, each of said third and fourth rigid links having said lengthwise dimension oriented perpendicular to said drive direction of said movable mass; and

a second spring system located in said second opening, said second spring system including a third spring head coupled to a third end of said third rigid link, a fourth spring head coupled a fourth end of said fourth rigid link, a third drive spring coupled to said third spring head and coupled to said movable mass, a fourth drive spring coupled to said fourth spring head and coupled to said movable mass, each of said first, second, third, and fourth spring heads including a torsion beam configured to enable rotation about an axis oriented substantially parallel to said drive direction, wherein said movable mass is resiliently suspended above said surface of said substrate via said first and second suspension structures and said first and second spring systems, said first and second spring systems enabling drive motion of said movable mass in said drive direction and enabling sense motion of said movable mass in a sense direction that is perpendicular to said surface of said substrate.

16. The MEMS device of claim 15 wherein said torsion beam comprises:

a first torsion beam section aligned with said axis;

a second torsion beam section aligned with said axis, said first and second torsion beams having a first beam end coupled to and extending from opposing lengthwise edges of a respective one of said first, second, third, and fourth rigid links; and

a connection bar aligned with said axis and interconnecting a second beam end of each of said first and second torsion beam sections.

18. A microelectromechanical systems (MEMS) device comprising:

a substrate;

a first movable mass having a first end region laterally displaced away from a second end region with a first central region interposed between said first and second end regions, wherein a first opening extends through said first end region and a second opening extends through said second end region;

a second movable mass having a third end region laterally displaced away from a fourth end region with a second central region interposed between said third and fourth end regions, wherein a third opening extends through said third end region and a fourth opening extends through said fourth end region;

suspension structures located in each of said first, second, third, and fourth openings, each of said suspension structures including an anchor coupled to a surface of said substrate, a first rigid link coupled to and extending from a first side of said first anchor, and a second rigid link coupled to and extending from a second side of said first anchor, each of said first and second rigid links having a lengthwise dimension oriented perpendicular to a drive direction of said movable mass, said drive direction being substantially parallel to said surface of said substrate;

spring systems located in each of said first, second, third, and fourth openings, each of said first spring systems including a first spring head coupled to a first end of said first rigid link, a second spring head coupled a second end of said second rigid link, a first drive spring coupled to said first spring head and coupled to an associated one of said first and second movable masses, and a second drive spring coupled to said second spring head and said associated one of said first and second movable masses; and

a couple spring structure having a stiff beam coupled to said surface of said substrate via a beam anchor, said couple spring structure interconnecting said first movable mass with said second movable mass, a second lengthwise dimension of said stiff beam being oriented perpendicular to said drive direction, wherein said first and second movable masses are resiliently suspended above said surface of said substrate via said suspension structures and said spring systems, said spring systems enable drive motion of said movable mass in said drive direction and enable sense motion of said first and second movable masses in a sense direction that is perpendicular to said surface of said substrate, and said couple spring structure is configured to pivot about an axis that is substantially perpendicular to said surface of said substrate in response to said drive motion of said first and second movable masses such that said first and second movable masses move in phase opposition with one another.

19. The MEMS device of claim 18 wherein said couple spring structure further comprises a torsion member interconnected between said stiff beam and said beam anchor, said torsion member enabling teeter totter motion of said stiff beam about an axis aligned with said torsion member in response to said sense motion of said first and second movable masses to enable parallel plate motion of first and said movable masses in phase opposition with one another in response to said sense motion.