MICRO ELECTRICAL MECHANICAL MAGNETIC FIELD SENSOR UTILIZING MODIFIED INERTIAL ELEMENTS

• US 20110192229A1
• Filed: 02/10/2010
• Published: 08/11/2011
• Est. Priority Date: 02/10/2010
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Chen, Po-Jui, Franke, Axel, Eckardt, Martin
• Granted Patent: US 8,418,556 B2
• Time in Patent Office: Days
• US Class Current: 73/514.32
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A micro electrical-mechanical system (MEMS) is disclosed. The MEMS includes a substrate, a first pivot extending upwardly from the substrate, a first lever arm with a first longitudinal axis extending above the substrate and pivotably mounted to the first pivot for pivoting about a first pivot axis, a first capacitor layer formed on the substrate at a location beneath a first capacitor portion of the first lever arm, a second capacitor layer formed on the substrate at a location beneath a second capacitor portion of the first lever arm, wherein the first pivot supports the first lever arm at a location between the first capacitor portion and the second capacitor portion along the first longitudinal axis, and a first conductor member extending across the first longitudinal axis and spaced apart from the first pivot axis.

Claims

1. A micro electrical-mechanical system (MEMS) comprising:

a substrate;

a first pivot extending upwardly from the substrate;

a first lever arm with a first longitudinal axis extending above the substrate and pivotably mounted to the first pivot for pivoting about a first pivot axis;

a first capacitor layer formed on the substrate at a location beneath a first capacitor portion of the first lever arm;

a second capacitor layer formed on the substrate at a location beneath a second capacitor portion of the first lever arm, wherein the first pivot supports the first lever arm at a location between the first capacitor portion and the second capacitor portion along the first longitudinal axis; and

a first conductor member extending across the first longitudinal axis and spaced apart from the first pivot axis.

2. The MEMS of claim 1, wherein:

the first capacitor portion is spaced apart from the first pivot axis by a first distance;

the second capacitor portion is spaced apart from the first pivot axis by a second distance; and

the first distance is greater than the second distance.

3. The MEMS of claim 1, wherein the first conductor member is positioned on an upper surface of the first lever arm.

4. The MEMS of claim 3, further comprising:

a first electrical biasing connection;

a second electrical biasing connection;

a first via extending between the first electrical biasing connection and a first end portion of the first conductor member for electrical coupling of the first electrical biasing connection and the first conductor member; and

a second via extending between the second electrical biasing connection and a second end portion of the first conductor member for electrical coupling of the second electrical biasing connection and the first conductor member.

5. The MEMS of claim 1, further comprising:

a memory in which command instructions are stored; and

a processor configured to execute the command instructions to

obtain a first voltage difference between the first capacitor layer and the first capacitor portion,

obtain a second voltage difference between the second capacitor layer and the second capacitor portion, and

provide an output associated with the strength of a first magnetic field extending along the first longitudinal axis based upon a difference between the first voltage difference and the second voltage difference.

6. The MEMS of claim 5, wherein the processor is further configured to execute the command instructions to:

provide an output associated with an acceleration of the first lever arm toward the substrate based upon a summation of the first voltage difference and the second voltage difference.

7. The MEMS of claim 1, wherein the first lever arm further comprises:

a base portion pivotably mounted to the first pivot;

a first spring arm portion extending between the base portion and the first capacitor portion; and

a second spring arm portion extending between the base portion and the second capacitor portion.

8. The MEMS of claim 1, further comprising:

a second pivot extending upwardly from the substrate;

a second lever arm with a second longitudinal axis extending above the substrate and pivotably mounted to the second pivot for pivoting about a second pivot axis;

a third capacitor layer formed on the substrate at a location beneath a third capacitor portion of the second lever arm;

a fourth capacitor layer formed on the substrate at a location beneath a fourth capacitor portion of the second lever arm, wherein the second pivot supports the second lever arm at a location between the third capacitor portion and the fourth capacitor portion along the second longitudinal axis; and

a second conductor member extending across the second longitudinal axis and spaced apart from the second pivot axis.

9. The MEMS of claim 8, wherein the second longitudinal axis is perpendicular to the first longitudinal axis.

10. The MEMS of claim 8, wherein the second longitudinal axis is parallel to the first longitudinal axis.

11. A method of forming a micro electrical-mechanical system (MEMS) comprising:

providing a substrate;

forming a first pivot extending upwardly from the substrate;

forming a first lever arm with a first longitudinal axis extending above the substrate to be pivotably mounted to the first pivot for pivoting about a first pivot axis;

forming a first capacitor layer on the substrate at a location selected to be beneath a first capacitor portion of the first lever arm;

forming a second capacitor layer on the substrate at a location selected to be beneath a second capacitor portion of the first lever arm, and selected such that the first pivot will support the first lever arm at a location between the first capacitor portion and the second capacitor portion along the first longitudinal axis; and

forming a first conductor member to extend across the first longitudinal axis at a location and to be spaced apart from the first pivot axis.

12. The method of claim 11, wherein:

the first capacitor portion is formed to be spaced apart from the first pivot axis by a first distance;

the second capacitor portion is formed to be spaced apart from the first pivot axis by a second distance; and

the first distance is greater than the second distance.

13. The method of claim 11, wherein the first conductor member is formed on an upper surface of the first lever arm.

14. The method of claim 13, further comprising:

forming a first electrical biasing connection;

forming a second electrical biasing connection;

forming a first via to extend between the first electrical biasing connection and a first end portion of the first conductor member for electrical coupling of the first electrical biasing connection and the first conductor member; and

forming a second via to extend between the second electrical biasing connection and a second end portion of the first conductor member for electrical coupling of the second electrical biasing connection and the first conductor member.

15. The method of claim 11, further comprising:

storing command instructions in a memory; and

configuring a processor to execute the command instructions to

obtain a first voltage difference between the first capacitor layer and the first capacitor portion,

obtain a second voltage difference between the second capacitor layer and the second capacitor portion, and

provide an output associated with the strength of a first magnetic field extending along the first longitudinal axis based upon a difference between the first voltage difference and the second voltage difference.

16. The method of claim 15, wherein configuring the processor further comprises configuring the processor to execute the command instructions to:

provide an output associated with an acceleration of the first lever arm toward the substrate based upon a summation of the first voltage difference and the second voltage difference.

17. The method of claim 11, wherein forming the first lever arm further comprises:

forming a base portion pivotably mounted to the first pivot;

forming a first spring arm portion extending between the base portion and the first capacitor portion; and

forming a second spring arm portion extending between the base portion and the second capacitor portion.

18. The method of claim 11, further comprising:

forming a second pivot to extend upwardly from the substrate;

forming a second lever arm with a second longitudinal axis to extend above the substrate to be pivotably mounted to the second pivot for pivoting about a second pivot axis;

forming a third capacitor layer on the substrate at a location selected to be beneath a third capacitor portion of the second lever arm;

forming a fourth capacitor layer on the substrate at a location selected to be beneath a fourth capacitor portion of the second lever arm, and selected so that the second pivot will support the second lever arm at a location between the third capacitor portion and the fourth capacitor portion along the second longitudinal axis; and

forming a second conductor member to extend across the second longitudinal axis and to be spaced apart from the second pivot axis.

19. The method of claim 18, wherein the second longitudinal axis is perpendicular to the first longitudinal axis.

20. The method of claim 18, wherein the second longitudinal axis is parallel to the first longitudinal axis.