MICROELECTROMECHANICAL INERTIAL SENSOR WITH ATMOSPHERIC DAMPING

• US 20110016972A1
• Filed: 03/25/2009
• Published: 01/27/2011
• Est. Priority Date: 03/27/2008
• Status: Active Grant

• Current Assignee: Maxim Integrated GmbH (Analog Devices, Inc.), Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., SD SensorDynamics AG
• Inventors: REINERT, Wolfgang
• Granted Patent: US 8,590,376 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• 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 microeletromechanical device, preferably an acceleration sensor or a multi-axis acceleration sensor, comprising a housing (19) with at least one first gas-filled cavity (5), in which cavity a first detection unit (9) is arranged movably relative to said housing (19) for detecting an acceleration to be detected,

said inertial sensor comprising a damping structure (16a, b, c, d) for damping movement of said first detection unit (9) in said housing (19) at least along an inertial sensors measurement direction (28).

2. The inertial sensor of claim 1, wherein said housing (19) comprises at least a second cavity (6), in which second cavity there are arranged a second detection unit (25) and a getter material (8).

3. The inertial sensor of claim 1 or 2, wherein said first and second cavities (5, 6) are hermetically sealed against each other and against the environment.

4. The inertial sensor of any of the preceding claims, wherein said damping structure (16a, b, c, d) is formed by arranging and configuring at least sections of said first detection unit (9) and of said housing (19) so as to form a clearance (23) therebetween in form of a narrow or constriction, wherein gas present in said cavity (5) flows through said clearance when said first detection unit (9) moves at least along measurement direction (28).

5. The inertial sensor of claim 4, wherein at least sections of said first detection unit (9) and of said housing (19) are each configured in a comb-like manner so as to have comb fingers (22, 24) and clearances (23) located in between.

6. The inertial sensor of claim 5, wherein said comb fingers (22) of said first detection unit (9) engage with said clearances (23) of the comb-like structure of said housing (19) and vice versa.

7. The inertial sensor of claim 5 or 6, wherein said comb fingers (22, 24) of the comb-like sections are arranged transversely with respect to measurement direction (28).

8. The inertial sensor of any of the preceding claims, wherein the pressure in said first cavity (5) is between 100 mbar and 300 mbar, preferably 200 mbar.

9. The inertial sensor of any of the preceding claims, wherein the pressure in said second cavity (6) is between 0.1 μ

bar and 1 mbar, preferably between 0.1 μ

bar and 0.1 mbar and particularly preferably 0.1 mbar.

10. The inertial sensor of any of the preceding claims, wherein said first cavity (5) has a different gas composition compared to said second cavity (6).

11. The inertial sensor of any of the preceding claims, wherein the housing-side section of said damping structure (16a, b, c, d) is electrically connected to a defined potential.

12. The inertial sensor of any of the preceding claims, wherein said second detection unit (25) arranged in said second cavity (6) forms a resonant rotation rate sensor (3).

13. The inertial sensor of any of the preceding claims, wherein a getter material (8) is provided in said first cavity (5), the gas absorption capabilities of which differ from those of the getter material (8) in said second cavity (6).

14. The inertial sensor of any of claims 1 to 12, wherein said first and second cavities (5, 6) contain the same getter material (8), however in a different amount or area relative to the cavity volume.

15. Multi-device for the fabrication of an inertial sensor according to any of claims 1 to 14.