Micromechanical sensor and method for manufacturing a micromechanical sensor

Patent metadata

Field	Value
Publication number	US-9625489-B2
Application number	US-201414468221-A
Country	US
Kind code	B2
Filing date	Aug 25, 2014
Priority date	Aug 26, 2013
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A micromechanical sensor is provided which includes a substrate having a main plane of extension and a rocker structure which is connected to the substrate via a torsion means. The torsion means extends primarily along a torsion axis, and the torsion axis is situated essentially in parallel to the main plane of extension of the substrate. The rocker structure is pivotable about the torsion axis from a neutral position into a deflected position, and the rocker structure has a mass distribution which is asymmetrical with respect to the torsion axis. The mass distribution is designed in such a way that a torsional motion of the rocker structure about the torsion axis is effected as a function of an inertial force which is oriented along a Z direction which is essentially perpendicular to the main plane of extension of the substrate.

First claim

What is claimed is:

1. A micromechanical sensor, comprising:
a substrate having a main plane of extension;
a torsion element;
a rocker structure connected to the substrate via the torsion element, wherein:
the torsion element extends primarily along a torsion axis situated essentially in parallel to the main plane of extension of the substrate,
the rocker structure is pivotable about the torsion axis from a neutral position into a deflected position,
the rocker structure includes a mass distribution which is asymmetrical with respect to the torsion axis, and
the mass distribution is designed in such a way that a torsional motion of the rocker structure about the torsion axis is effected as a function of an inertial force on the rocker structure which is oriented along a Z direction which is essentially perpendicular to the main plane of extension of the substrate,
wherein at least one of:
a damping structure is configured for damping a translational motion of the rocker structure along an X direction which is essentially in parallel to the main plane of extension of the substrate, and
the torsion element includes a first torsion element and a second torsion element which is connected to the first torsion element, the first torsion element having a first main direction of extension which extends essentially in parallel to the torsion axis, and the second torsion element having a second main direction of extension which extends essentially in parallel to the torsion axis, the first and second main directions of extension being situated at a distance from one another along a projection direction which is essentially in parallel to the Z direction, the first and the second torsion element at least partially overlapping one another along the projection direction, the micromechanical sensor being configured in such a way that a first resonant frequency of a torsion mode of the rocker structure about the torsion axis is less than a second resonant frequency of a vibration mode of the rocker structure, the vibration mode including a vibrational motion of the rocker structure along a plane of vibration which is essentially in parallel to the main plane of extension.

2. The micromechanical sensor as recited in claim 1 , wherein at least one of:
the vibrational motion includes a translational motion of the rocker structure along the X direction, the X direction being situated essentially perpendicularly with respect to the torsion axis, and
the vibrational motion includes a rotary motion of the rocker structure about an axis which is essentially in parallel to the Z direction.

3. The micromechanical sensor as recited in claim 1 , wherein the torsion element has a torsion element length which extends along the torsion axis from one end to another end of the torsion element, and wherein at least one of:
the torsion element length is less than one-half of a rocker width of the rocker structure which extends along the torsion axis, and
the first torsion element has the torsion element length along the first main direction of extension, the second torsion element having the torsion element length along the second main direction of extension, the first and second torsion elements being connected to one another via two or more connecting elements, the two or more connecting elements being situated at a distance from one another along the Y direction.

4. The micromechanical sensor as recited in claim 3 , wherein the torsion element length is less than one-third of the rocker width.

5. The micromechanical sensor as recited in claim 3 , wherein the torsion element length is less than one-fourth of the rocker width.

6. The micromechanical sensor as recited in claim 3 , wherein the torsion element length is less than one-fifth of the rocker width.

7. The micromechanical sensor as recited in claim 3 , wherein the first and second torsion elements are connected to one another solely indirectly.

8. The micromechanical sensor as recited in claim 1 , wherein the rocker structure includes a further torsion element that extends primarily along the torsion axis, the torsion element and the further torsion element in each case being connected to the rocker structure at ends facing away from each other, and in each case being connected to the substrate at ends facing each other via an anchoring element situated between the torsion element and the further torsion means element, the torsion element length of the torsion element and a further torsion element length of the further torsion means being essentially equal.

9. The micromechanical sensor as recited in claim 1 , wherein the first torsion element has a first torsion element structure width which extends essentially in parallel to the main plane of extension, and a first torsion element structure height which extends essentially in parallel to the Z direction, the second torsion element having a second torsion element structure width which extends essentially in parallel to the main plane of extension, and a second torsion element structure height which extends essentially in parallel to the Z direction, at least one of the first and second torsion element structure widths and the first and second torsion element structure heights being configured in such a way that the first resonant frequency is less than the second resonant frequency, wherein at least one of:
the first torsion element structure width being 0.5 times to 2 times the second torsion element structure width, and/or
the first torsion element structure height being 0.01 times to 0.4 times the second torsion element structure height.

10. The micromechanical sensor as recited in claim 9 , wherein the first resonant frequency is less than the second resonant frequency by one order of magnitude.

11. The micromechanical sensor as recited in claim 9 , wherein the first torsion element structure width is 0.8 times to 1.4 times the second torsion element structure width.

12. The micromechanical sensor as recited in claim 9 , wherein the first torsion element structure width is 1.0 times to 1.2 times the second torsion element structure width.

13. The micromechanical sensor as recited in claim 9 , wherein the first torsion element structure height is 0.05 times to 0.2 times the second torsion element structure height.

14. The micromechanical sensor as recited in claim 9 , wherein the first torsion element structure height is 0.1 times the second torsion element structure height.

15. The micromechanical sensor as recited in claim 1 , wherein at least one of:
at least one of the first torsion element has a first ladder structure and the second torsion element has a second ladder structure, at least one of the first ladder structure and the second ladder structure each having two side rail elements which are connected to one another via multiple transverse webs, and
at least one of the first torsion element extends essentially along the first main direction of extension in a meandering manner and the second torsion element extends essentially along the second main direction of extension in a meandering manner.

16. The micromechanical sensor as recited in claim 1 , wherein the damping structure is configured for damping the translational motion of the rocker structure along the X direction and/or for damping the rotary motion of the rocker structure about the axis, in particular the damping structure including one or multiple damping elements, in particular the one or multiple damping elements being situated in a recess in the rocker structure which extends through the rocker structure along a projection directio

Assignees

• Bosch Gmbh Robert

Inventors

• Ullrich Guenther-Nino-Carlo
• Orto Andrea

Classifications

• B81B2203/058

  Rotation out of a plane parallel to the substrate · CPC title

• B81B3/0027

  Structures for transforming mechanical energy, e.g. potential energy of a spring into translation, sound into translation · CPC title

• B81C1/00134

  comprising flexible or deformable structures (manufacture of MEMS devices for specific applications, see relevant places, e.g. gyroscopes G01C19/5719, pressure sensors G01L9/0042, accelerometers G01P15/0802, acoustic transducers or diaphragms therefor H04R31/00) · CPC title

• B81B2201/0235

  Accelerometers · CPC title

• G01P15/125 Primary

  by capacitive pick-up · CPC title