Micro-machined electromechanical system (MEMS) accelerometer device having arcuately shaped flexures

• US 6,991,957 B2
• Filed: 11/30/2004
• Issued: 01/31/2006
• Est. Priority Date: 08/20/2001
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Eskridge, Mark H.
• Primary Examiner(s): THAI, LUAN C
• Application Number:
  US11/000,652
• Publication Number:
  US 20050202585A1
• Time in Patent Office: 427 Days
• Field of Search: 438/50, 257/415, 735/142.9
• US Class Current: 438/50
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2203/0181 See-saws
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: B81C 2201/0133 Wet etching
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

A method for suspending a movable structure form a support structure wherein first and second flat and thin arcuately shaped flexures are formed having spaced apart substantially planar and parallel opposing surfaces, each of the first and second flexures being structured for connection between a support structure and a movable structure to be suspended from the support structure and being aligned along a common axis of rotation between the support structure and the movable structure.

Claims

1. A method for suspending a movable structure to be suspended from a support structure, the method comprising:

forming in a layer of epitaxial semiconductor material having spaced apart substantially planar and parallel opposing surfaces a movable structure to be suspended adjacent to a support structure with a peripheral edge of the movable structure spaced apart from a peripheral edge of the support structure;

forming in the layer of epitaxial semiconductor material a plurality of pairs of first and second arcuately shaped flexures having spaced apart substantially planar and parallel opposing surfaces, each of the pairs of flexures interconnecting the peripheral edge of the movable structure with the peripheral edge of the movable structure along a common axis of rotation.

2. The method of claim 1, further comprising spacing the pairs of arcuately shaped flexures along the peripheral edge of the movable structure facing the peripheral edge of the support structure.

3. The method of claim 1, further comprising spacing apart the first and second arcuately shaped flexures of each pair of arcuately shaped flexures.

4. The method of claim 1, further comprising aligning the first and second arcuately shaped flexures of each pair of arcuately shaped flexures with respective outer arcuate shapes facing in opposite directions.

5. The method of claim 1, further comprising forming part-circular suspension members by interconnecting intermediate arc portions of the first and second arcuately shaped flexures of each pair of arcuately shaped flexures.

6. The method of claim 1, further comprising forming substantially circular suspension members by forming interconnected part-circular first and second arcuately shaped flexures.

7. A method for suspending a movable structure to be suspended from a support structure, the method comprising:

forming in a layer of epitaxial semiconductor material a movable structure to be suspended adjacent to a support structure with a peripheral edge of the movable structure being spaced apart from a peripheral edge of the support structure;

forming in the layer of epitaxial semiconductor material a pair of first and second arcuately shaped flexures having spaced apart substantially planar and parallel opposing surfaces, the pair of flexures interconnecting the peripheral edge of the movable structure with the peripheral edge of the movable structure along a common axis of rotation.

8. The method of claim 7, further comprising a plurality of the pairs of first and second arcuately shaped flexures spaced along the peripheral edge of the movable structure facing the peripheral edge of the support structure.

9. The method of claim 7, further comprising spacing apart the first and second arcuately shaped flexures.

10. The method of claim 7, further comprising aligning the pair of first and second arcuately shaped flexures with respective outer arcuate shapes facing in opposite directions.

11. The method of claim 7, further comprising forming part-circular suspension members by interconnecting intermediate arc portions of the first and second arcuately shaped flexures.

12. The method of claim 7, further comprising forming a substantially circular suspension member by forming interconnected part-circular first and second arcuately shaped flexures.

13. A method for fabricating an acceleration sensor, the method comprising:

in an epitaxial layer of semiconductor material having spaced apart substantially planar and parallel opposing surfaces, forming a support frame and a proof mass adjacent to the support frame, the proof mass being structured for travel in a direction crosswise to the plane of the substrate, and

in the epitaxial layer, forming a pliant suspension member interconnected between the support frame and the proof mass, the suspension member being formed of first and second arcuately shaped flexure members each having a cross-section that is wider in a plane crosswise to the direction of travel of the proof mass relative to a plane aligned with the direction of travel.

14. The method of claim 13, further comprising forming a plurality of the pliant suspension members formed in the epitaxial layer and interconnected between the support frame and the proof mass.

15. The method of claim 14, further comprising configuring the first and second arcuately shaped flexure members of each of the plurality of pliant suspension members formed in the substrate and interconnected between the support frame and the proof mass with an outer arcuate shape of the first flexure member facing oppositely from an outer arcuate shape of the second flexure member.

16. The acceleration sensor of claim 15, further comprising configuring the oppositely facing first and second arcuately shaped flexure members of each of the plurality of pliant suspension members positioned to share a common centerline such as to form a single arcuately shaped suspension member.

17. The acceleration sensor of claim 15, further comprising configuring the oppositely facing first and second arcuately shaped flexure members of each of the plurality of pliant suspension members in a part-circular shape such as to form a single circular suspension member.

18. The acceleration sensor of claim 15, further comprising configuring the oppositely facing first and second arcuately shaped flexure members of each of the plurality of pliant suspension members in a part-circular shape having interconnected corresponding portions intermediate along the part-circular shape such as to form a single substantially cruciform shaped suspension member.