Suspension for micromechanical structure and micromechanical acceleration sensor

• US 5,646,347 A
• Filed: 08/31/1995
• Issued: 07/08/1997
• Est. Priority Date: 09/03/1994
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Offenberg, Michael, Elsner, Bernhard, Weiblen, Kurt
• Primary Examiner(s): Chapman, John E.
• Application Number:
  US08/521,942
• Time in Patent Office: 677 Days
• Field of Search: 73/514.32, 73/514.38, 73/514.18, 73/514.24, 73/497, 73/514.29
• US Class Current: 73/514.32
• CPC Class Codes: G01P 1/006 used for thermal compensation
• 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

Abstract

A suspension or an acceleration sensor having a suspension is proposed, by means of which a micromechanical structure or the acceleration sensor is anchored on a substrate. The suspension takes place by means of lever elements on which an equalizing beam acts. The lever elements are deformed by the stresses in the equalizing beam with respect to the substrate in such a way that the stresses in the microstructure with respect to the substrate are either compensated for or, alternatively, are converted from compressive stresses to tensile stresses or from tensile stresses to compressive stresses.

Claims

1. A device comprising:

a substrate;

a micromechanical structure;

a first anchorage mounted on the substrate;

at least one lever element, a first side of the lever element being attached to the first anchorage, and a second side of the lever element being attached to the micromechanical structure to form a first point of action; and

an equalizing element for eliminating stresses on the micromechanical structure, the equalizing element being attached to the second side of the lever element to form a second point of action, the lever element being adapted to be flexed by a stress in the equalizing element.

2. The device according to claim 1, wherein the equalizing element includes a beam.

3. The device according to claim 1, further comprising:

a second anchorage mounted on the substrate, the second anchorage coupling the micromechanical structure to the substrate; and

a second lever element, wherein

a first side of the second lever element is attached to the second anchorage, and a second side of the second lever element is attached to the micromechanical structure to form a third point of action,

the equalizing element is attached to the second lever element at a fourth point of action, and

the second lever element is adapted to be flexed by a stress in the equalizing element.

4. The device according to claim 3, wherein:

the second point of action is between the first point of action and the first anchorage; and

the fourth point of action is between the third point of action and the second anchorage.

5. A device comprising:

a substrate;

a micromechanical structure;

a first anchorage mounted on the substrate;

at least one lever element, a first side of the lever element being attached to the first anchorage, and a second side of the lever element being attached to the micromechanical structure to form a first point of action; and

an equalizing element for eliminating stresses on the micromechanical structure, the equalizing element being attached to the second side of the lever element to form a second point of action, the lever element being adapted to be flexed by a stress in the equalizing element,

wherein the micromechanical structure includes a seismic mass suspended on at least one bending element, the bending element is suspended by the lever element, and the seismic mass is adapted to be deflected by an acceleration, the device thereby functioning as an acceleration sensor.

6. The device according to claim 5, wherein the seismic mass includes at least one movable electrode arranged between at least two stationary electrodes, the stationary electrodes being attached to at least one additional anchorage.

7. The device according to claim 6, wherein the seismic mass, the movable electrode, the bending element, the lever element, and the equalizing element are composed of the same preselected material.

8. The device according to claim 7, wherein the preselected material includes silicon.

9. The device according to claim 7, wherein the preselected material includes a metal.

10. The device according to claim 5, wherein the equalizing element is adapted for adjusting tensile forces in the at least one bending element.