Micromechanical device with an actively deflectable element

Patent metadata

Field	Value
Publication number	US-9676607-B2
Application number	US-201615098089-A
Country	US
Kind code	B2
Filing date	Apr 13, 2016
Priority date	Apr 15, 2015
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Micromechanical devices include actively deflectable elements. The activation is performed by a layer stack which causes the deflection responsive to attractive forces acting upon the layers of the layer stack.

First claim

The invention claimed is:

1. A micromechanical device comprising a deflectable element comprising a layer stack of a first layer and a second layer, wherein the first layer and second layer are mechanically fixed to each other by spacers so that the first layer is spaced apart from the second layer in a layer stack direction, wherein
the spacers are inclined relative to the layer stack direction into a lateral direction,
wherein the deflectable element is deflected along the lateral direction into or opposed to the layer stack direction by way of exposing the layer stack to an attractive force between the first layer and the second layer.

2. The micromechanical device according to claim 1 , wherein a ratio between thicknesses of the first and second layers lies between 0.2 and 5, both inclusively.

3. The micromechanical device according to claim 1 , wherein a ratio between thicknesses of the first and second layers lies between 3/4 and 4/3, both inclusively.

4. The micromechanical device according to claim 1 , wherein a gap between the first and second layers is, with neglecting the spacers, of planar shape.

5. The micromechanical device according to claim 1 , wherein the spacers longitudinally extend in a further lateral direction transverse to the lateral direction and are distributed at a predetermined mean pitch along the lateral direction.

6. The micromechanical device according to claim 1 , wherein a mean lateral width of the spacers measured along the lateral direction lies between 0.001 and 1000 times a distance between the first and second layers.

7. The micromechanical device according to claim 1 , wherein the layer stack forms a plate capacitor with the first and second layers forming electrodes of the plate capacitor.

8. The micromechanical device according to claim 1 , wherein the spacers are of a parallelepiped shape or formed like tilted walls comprising a conical cross-section.

9. The micromechanical device according to claim 1 , wherein the spacers are formed, at least partly, of an insulating material.

10. The micromechanical device according to claim 1 , wherein each spacer is, at least partly, formed of an insulating material such that an end of the respective spacer which faces the first layer is insulated from an end of the respective spacer which faces the second layer by the insulating material.

11. The micromechanical device according to claim 9 , wherein each spacer is also formed of a conductive material of the first layer and the second layer with the conductive material of the first layer and the second layer extending into the spacers so as to abut, within the spacers, on the insulating material.

12. The micromechanical device according to claim 11 , wherein the conductive material of the first layer and the second layer abuts on the insulating material along a surface which, when exposing the layer stack to the attractive force, crosses a tensile stress field developing in the spacers due to the attractive force perpendicularly and is in parallel to a compressive stress of a compression field in the spacers developing in the spacers due to the attractive force.

13. The micromechanical device according to claim 12 , wherein the conductive material of the first layer and the second layer is interdigitated with the insulating material of the spacers.

14. The micromechanical device according to claim 1 , wherein, in the segments, protrusions of the first layer and the second layer protrude into the gap so as to interdigitally engage with each other.

15. The micromechanical device according to claim 14 , wherein the protrusions of the first layer and the second layer protrude substantially in parallel to each other in a direction substantially transverse to a relative direction along which portions of the first and second layers from which the protrusions protrude, move relative to each other responsive to the deflection of the deflective element by way of the exposition of the layer stack to the attractive force.

16. The micromechanical device according to claim 1 , wherein an inner surface of the gap is at least partially covered by an insulating film so that the first and second layers keep on being insulated from each other even in case of a mechanical contact of the first and second layers due to the attractive force between the first layer and the second layer exceeding a pull-in force.

17. The micromechanical device according to claim 1 , wherein the deflectable element is formed of a part of a substrate which is bordered, except for at least a suspension site of the deflectable element, by an opening continuous in a substrate thickness direction, wherein the layer stack direction is in the substrate thickness direction.

18. The micromechanical device according to claim 1 , wherein the deflectable element is formed of a part of a substrate which is bordered, except for at least a suspension site of the deflectable element, by an opening continuous in a substrate thickness direction, wherein the layer stack direction is lateral with respect to the substrate.

19. The micromechanical device according to claim 1 , wherein one of the first and second layers is unsuspended whereas the other of the first and second layers is suspended to a suspension site of the deflectable element.

20. A micromechanical device comprising a deflectable element, wherein the deflectable element comprises a laminar actuator which is formed as a layer stack comprising a distal layer and a proximal layer extending along and, in a deflection direction, spaced apart from a neutral axis of the deflectable element, wherein the proximal layer is arranged between the distal layer and the neutral axis and the layer stack is segmented into segments along a lateral direction, wherein the distal layer is mechanically fixed between the segments so that the distal layer is spaced apart from the proximal layer and so that the deflectable element is deflected along the lateral direction into or opposed to the deflection direction by way of exposing the layer stack to an attractive force between the proximal layer and the distal layer, wherein
in each segment, a surface of the distal layer, facing the proximal layer via a gap, bulges out towards or away from the neutral axis wherein a ratio of half a length of the respective segment in the lateral direction to a difference between a maximum distance of said surface from the neutral axis and a minimum distance of said surface from the neutral axis lies between sin(1°) and sin(10°), both inclusively.

21. The micromechanical device according to claim 20 , wherein the surfaces bulge out in each segment rounded, angled or stepped.

22. The micromechanical device according to claim 20 , wherein the layer stack forms a plate capacitor with the proximal layer forming a proximal electrode of the plate capacitor and the distal layer forming a distal electrode of the plate capacitor.

23. The micromechanical device according to claim 20 , wherein, in each segment, said surface is formed such that said surface comprises exclusively at least one plane portion and at least two ramp portions following each other along the lateral direction such that the at least one plane portion is parallel to the neutral axis and the at least two ramp portions are inclined relative to the neutral axis with at least two of the at least two ramp portions being oppositely inclined relative to the lateral direction.

24. The micromechanical device acco

Assignees

• Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E V

Inventors

• Gaudet Matthieu
• Schimmanz Klaus
• Stolz Michael
• Langa Sergiu
• Conrad Holger
• Kaiser Bert

Classifications

• B81B2203/0127

  Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function · CPC title

• B81B3/0021 Primary

  Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00) · CPC title

• B81B2203/0118

  Cantilevers · CPC title

• B81B2201/032

  Bimorph and unimorph actuators, e.g. piezo and thermo · CPC title

• B81B3/0094 Primary

  Constitution or structural means for improving or controlling physical properties not provided for in B81B3/0067 - B81B3/0091 · CPC title