Microelectromechanical inertial sensor with atmospheric damping

• US 8,590,376 B2
• Filed: 03/25/2009
• Issued: 11/26/2013
• Est. Priority Date: 03/27/2008
• Status: Active Grant

• Current Assignee: Maxim Integrated GmbH (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated GmbH (Analog Devices, Inc.), Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Reinert, Wolfgang, Heller, Martin
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US12/934,783
• Publication Number:
  US 20110016972A1
• Time in Patent Office: 1,707 Days
• Field of Search: 735/10, 735/11, 734/93, 735/143.2, 735/142.9, 735/041.2, 735/041.4, 735/040.4
• US Class Current: 73/493
• CPC Class Codes: G01C 19/5783 Mountings or housings not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01P 1/003 used for damping
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: Y10T 29/52 Plural diverse manufacturing apparatus

Abstract

The present invention relates to an inertial sensor, preferably an acceleration sensor or multi-axis acceleration sensor as a microelectromechanical construction element, said sensor comprising a housing with at least one first gas-filled cavity in which a first detection unit is disposed moveably relative to the housing for detection of an acceleration to be detected, wherein the inertial sensor comprises a damping structure.

Claims

1. An inertial sensor in form of a microelectromechanical device,

comprising a housing with at least one first gas-filled cavity,

in which cavity a first detection unit is arranged movably relative to said housing for detecting an acceleration to be detected,

said inertial sensor comprising a damping structure for damping movement of said first detection unit in said housing at least along an inertial sensor measurement direction,

wherein said housing comprises at least a second cavity,

wherein a second detection unit and a getter material are arranged in said second cavity,

wherein said damping structure is formed by arranging and configuring at least sections of said first detection unit and of said housing so as to form a clearance therebetween in form of a narrow or constriction, wherein gas present in said first cavity flows through said clearance when said first detection unit moves at least along measurement direction,

wherein a housing-side section of the damping structure comprises an electrically conductive connection with a defined potential which does not provide any active electrical excitation or read-out function.

2. The inertial sensor of claim 1, wherein said first and second cavities are hermetically sealed against each other and against the environment.

3. The inertial sensor of claim 1, wherein at least sections of said first detection unit and of said housing are each configured in a comb-like manner so as to provide a comb-like structure having comb fingers and clearances located in between.

4. The inertial sensor of claim 3, wherein said comb fingers of the first detection unit engage with said clearances of the comb-like structure of said housing and vice versa.

5. The inertial sensor of claim 3, wherein said comb fingers of the comb-like structure are arranged transversely with respect to measurement direction.

6. The inertial sensor of claim 1, wherein the pressure in said first cavity is between 100 mbar and 300 mbar.

7. The inertial sensor of claim 1, wherein pressure in said second cavity is between 0.1 μ

bar and 1 mbar.

8. The inertial sensor of claim 1, wherein said first cavity has a different gas composition compared to said second cavity.

9. The inertial sensor of claim 1, wherein a housing-side section of said damping structure is electrically connected to a defined potential.

10. The inertial sensor of claim 1, wherein said second detection unit arranged in said second cavity forms a resonant rotation rate sensor.

11. The inertial sensor of claim 1, wherein a getter material is provided in said first cavity, the gas absorption capabilities of which differ from those of the getter material in said second cavity.

12. The inertial sensor of claim 1, wherein said first and second cavities contain a same getter material, however in a different amount or area relative to the cavity volume.

13. The inertial sensor of claim 6, wherein pressure in said first cavity is 200 mbar.

14. The inertial sensor of claim 7, wherein pressure in said second cavity is between 0.1 μ

bar and 0.1 mbar.

15. The inertial sensor of claim 14, wherein pressure in said second cavity is 0.1 mbar.

16. The inertial sensor of claim 1, the microeletromechanical device being an acceleration sensor or a multi-axis acceleration sensor.