ELECTROSTATICALLY DEFLECTABLE MICROMECHANICAL DEVICE

• US 20160173001A1
• Filed: 12/14/2015
• Published: 06/16/2016
• Est. Priority Date: 12/15/2014
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Langa, Sergiu, Stolz, Michael, Conrad, Holger, Schenk, Harald
• Granted Patent: US 10,483,876 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/032 Bimorph and unimorph actuators, e.g. piezo and thermo
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/0127 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 Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: H02N 1/006 of the gap-closing type H02N1/004 takes precedence

Abstract

A micromechanical device with electrostatically caused deflection by a plate capacitor extending along and spaced apart from the neutral fiber of the deflectable element is improved with regard to its manufacturing complexity and/or with regard to its operating characteristics, such as, for example, maximum voltage applicable or deflectability, by using a continuous insulation layer between the distal and proximal electrodes of the plate capacitor, or else the proximal electrode is structured so as to have gaps at the segment boundaries where the distal electrode is mechanically fixed so as to be laterally spaced apart from the distal electrode. Both procedures avoid the problems of generating a roughness of the surface of the proximal electrode facing the distal electrode, as would otherwise be necessitated by etching an insulation layer for providing spacers between the distal and proximal electrodes at the segment boundaries.

Claims

1. A micromechanical device comprising:

a deflectable element, wherein the deflectable element comprises;

an electrostatic actuator which is implemented as a plate capacitor extending along and spaced apart in a deflection direction from a neutral fiber of the deflectable element,

the capacitor comprising a distal electrode and a proximal electrode, wherein the proximal electrode is arranged between the distal electrode and the neutral fiber and the plate capacitor is subdivided along a direction into segments between which the distal electrode is fixed mechanically at segment boundaries such that the deflectable element, by providing the plate capacitor with a voltage, is deflected along the direction in or opposite to the deflection direction; and

wherein the proximal electrode is arranged at a side of an insulation material of the deflectable element facing the distal electrode and is structured along the direction so as to comprise gaps at the segment boundaries such that the distal electrode is mounted mechanically to the insulation material at the segment boundaries in a manner laterally spaced apart from the proximal electrode.

2. The micromechanical device in accordance with claim 1, wherein the distal electrode is formed to be continuous in the direction across the segments and segment boundaries.

3. The micromechanical device in accordance with claim 1, wherein the side of the insulation material facing the distal electrode is implemented to be planar.

4. The micromechanical device in accordance with claim 1, wherein the proximal electrode comprises one portion per segment, wherein the portions are spaced apart from one another at the segment boundaries via the gaps, wherein the portions, at a side facing the distal electrode, due to a multi-layered setup, comprise a side facing the distal electrode and facing away from the insulation material, which comprises a non-planar shape.

5. The micromechanical device in accordance with claim 4, wherein the deflectable element comprises a beam or membrane through which passes the neutral fiber, wherein the insulation material is formed by an insulation layer which is arranged at a side of the beam or membrane facing the distal electrode.

6. The micromechanical device in accordance with claim 5, wherein the insulation layer is a conformingly deposited insulation layer of basically constant thickness.

7. The micromechanical device in accordance with claim 4, wherein the proximal electrode or the distal electrode is electrically short-circuited to the beam or membrane.

8. The micromechanical device in accordance with claim 3, wherein the portions of the proximal electrode are short-circuited to one another to be placed at a common potential, are drivable individually to be placed at mutually different potentials, are short-circuited in groups to be set in groups to different potentials.

16. The micromechanical device in accordance with claim 1, wherein the distal and/or proximal electrode(s) is/are formed from titanal aluminide, doped polysilicon, doped amorphous silicon or aluminum.

17. The micromechanical device in accordance with claim 1, wherein the insulation layer is formed from aluminum oxide or thermal silicon oxide.

18. The micromechanical device in accordance with claim 1, wherein a width of a slot between the distal and proximal electrodes within the segments is basically constant.

19. The micromechanical device in accordance with claim 1, wherein a slot between the distal electrode and the proximal electrode within the segments comprises a cross-sectional profile which is equal among the segments.

20. The micromechanical device in accordance with claim 19, wherein the profile comprises a cross-section arched in the direction of the neutral fiber or away from the neutral fiber or a pointed cross-section.

21. The micromechanical device in accordance with claim 1, wherein the deflectable element is formed from a semiconductor material, metal, plastic, polymer or FR4.

22. The micromechanical device in accordance with claim 1, wherein a thickness of the deflectable element in a direction of curvature into which the deflectable element is curved by providing the plate capacitor with a voltage is larger by more than 5 times a thickness of the distal electrode and a thickness of a slot between the distal and proximal electrodes in the segments together.

24. The micromechanical device in accordance with claim 1, wherein the deflectable element is implemented to be a membrane or beam.

25. The micromechanical device in accordance with claim 1, wherein a thickness of the deflectable element, measured in a direction of curvature into which the deflectable element is curved by providing the plate capacitor with a voltage, is varied along the direction such that the degree of deflection also varies along the direction.

26. The micromechanical device in accordance with claim 1, wherein a slot between the distal and proximal electrodes transverse to the direction and transverse to a direction of curvature into which the deflectable element is curved by providing the plate capacitor with a voltage, within the segments, is closed.

27. The micromechanical device in accordance with claim 1, wherein a slot between the distal and proximal electrodes within the segments is filled by air, polymer, a dielectric elastic material.

28. A method for operating a micromechanical device in accordance with claim 1.

9. A micromechanical device comprising:

a deflectable element, wherein the deflectable element comprises;

an electrostatic actuator which is implemented as a plate capacitor extending along and spaced apart in a direction of deflection from a neutral fiber of the delectable element, the capacitor comprising a distal and a proximal electrode,

wherein the distal electrode is arranged on a side of the place capacitor facing away from the neutral fiber and the place capacitor is subdivided along a direction into segments between which the distal electrode and the proximal electrode are connected mechanically at segment boundaries such that, by providing the plate capacitor with a voltage, the deflectable element is deflected along the direction in or opposite to the direction of deflection, and

wherein an insulation layer extends between the distal electrode and the proximal electrode in a manner formed continuously in the direction across the segments and segment boundaries so as to insulate same from one another such that mechanical coupling at the segment boundary is realized indirectly via the insulation layer.

10. The micromechanical device in accordance with claim 9, wherein the proximal electrode and the distal electrode are formed continuously in the direction across the segments and segment boundaries.

11. The micromechanical device in accordance with claim 9, wherein the insulation layer abuts on the proximal electrode.

12. The micromechanical device in accordance with claim 9, wherein the deflectable element comprises a beam or membrane through which passes the neutral fiber, wherein the beam or membrane abuts on the insulation layer at a side facing the distal electrode and serves itself as the proximal electrode.

13. The micromechanical device in accordance with claim 9, wherein a side of the proximal electrode facing the distal electrode is implemented to be planar and the insulation layer is a planar layer abutting thereon, wherein slots of the plate capacitor between the proximal and distal electrodes in the segments result from a deviation, repeating per segment, of the distal electrode from a planar shape extending in parallel to the insulation layer.

14. The micromechanical device in accordance with claim 9, wherein a side of the proximal electrode facing the distal electrode comprises one recess or projection extending transverse to the direction per segment and the insulation layer is a planar conforming layer abutting on the side of the proximal electrode facing the distal electrode.

15. The micromechanical device in accordance with claim 14, wherein slots of the plate capacitor between the proximal and distal electrodes in the segments comprise an essentially constant thickness.

23. The micromechanical device in accordance with claim 9, wherein a thickness of the deflectable element in a direction of curvature into which the deflectable element is curved by providing the plate capacitor with a voltage is larger by more than 5 times a thickness of the distal electrode and a thickness of a slot between the distal and proximal electrodes in the segments together.

29. A method for operating a micromechanical device in accordance with claim 9.

30. A method for manufacturing a micromechanical device, comprising:

providing a beam or membrane functioning as or comprising a proximal electrode;

applying an insulation layer onto the proximal electrode in a manner formed continuously along a segment succession direction;

applying sacrificial material onto the insulation layer in a manner structured along the segment succession direction such that the insulation layer is covered by the sacrificial material in segments in the segment succession direction and is exposed in segment boundaries between the segments; and

applying a distal electrode onto the insulation layer covered segment by segment such that the distal electrode is coupled to the proximal electrode indirectly via the insulation layer such that, by providing a plate capacitor formed by the distal and proximal electrodes with a voltage, the beam or membrane is deflected along the direction transverse to the plate capacitor.

31. A method for manufacturing a micromechanical device, comprising:

forming a proximal electrode on a surface of an insulation material of a beam or a membrane such that the proximal electrode is structured into portions with gaps therebetween along a segment succession direction;

applying sacrificial material onto the surface and the portions in a manner structured along the segment succession direction such that the insulation material is exposed inside the gaps in the segment succession direction and the portions of the proximal electrode are covered by the sacrificial material up to the gaps along the segment succession direction; and

applying a distal electrode onto the sacrificial material such that the distal electrode is mechanically fixed to the insulation material inside the gaps such that, by providing a plate capacitor formed by the distal and proximal electrodes with a voltage, the beam or membrane is deflected along the direction transverse to the plate capacitor.