MEMS ACTUATOR, IN PARTICULAR A MICROMIRROR, WITH INCREASED DEFLECTABILITY

Abstract

A MEMS actuator comprising a frame structure and at least one actuator arm. The actuator arm is connected at a first end to the frame structure and at a second end to an actuator body. The MEMS actuator is characterized in that the at least one actuator arm has a meander structure comprising two or more actuator sections. The two or more actuator sections are oriented substantially perpendicular to the longitudinal axis of the actuator arm. Furthermore, the two or more actuator sections comprise at least one layer of an actuator material, wherein a movement of the actuator body can be effected by actuating the two or more actuator sections. Further disclosed is a method for producing the MEMS actuator.

Claims

1. A MEMS actuator comprising a frame structure and at least one actuator arm, wherein the actuator arm is connected at a first end to the frame structure and at a second end to an actuator body, wherein the at least one actuator arm has a meander structure comprising two or more actuator sections, wherein the two or more actuator sections are oriented substantially perpendicular to a longitudinal axis of the actuator arm and comprise at least one layer of an actuator material and wherein a movement of the actuator body can be effected by actuation of the two or more actuator sections.

2. The MEMS actuator according to claim 1, wherein the movement of the actuator body comprises translation, rotation, torsion and/or tilting.

3. The MEMS actuator according to claim 1, wherein the two or more actuator sections are formed by applying at least one layer comprising an actuator material to a meander structure of a substrate.

4. The MEMS actuator according to claim 3, wherein regions of the meander structure of the substrate are oriented orthogonally to the surface of the substrate to form the two or more actuator sections.

5. The MEMS actuator according to claim 1, wherein the two or more actuator sections comprise at least two layers.

6. The MEMS actuator according to claim 5, wherein one layer comprises an actuator material and a second layer comprises a mechanical support material and/or wherein both layers comprise an actuator material.

7. The MEMS actuator according to claim 1, wherein the actuator material comprises a piezoelectric material, a polymer piezoelectric material, electroactive polymers (EAP) and/or a thermosensitive material.

8. The MEMS actuator according to claim 1, wherein the actuator arm is in contact with at least one electrode and the actuator sections are actuated by an electrical control signal to effect lateral bendings or deflections.

9. The MEMS actuator according to claim 1, wherein the MEMS actuator has a fixing element which is connected to the actuator body so that the actuator body can be tilted along a pivot point and/or a pivot axis by applying the control signal.

10. The MEMS actuator according to claim 1, wherein the first end of the actuator arm is connected to the frame structure via a mechanically rigid or flexible connector.

11. The MEMS actuator according to claim 1, wherein by actuating the two or more actuator sections, the actuator body can be tilted by at least 10° about a pivot point.

12. The MEMS actuator according to claim 1, wherein the at least one actuator arm comprises more than 3 actuator sections.

13. The MEMS actuator according to claim 1, wherein the actuator body is connected to the frame structure via one, two, three or four actuator arms.

14. The MEMS actuator according to claim 13, wherein the one, two, three or four actuator arms are in one plane.

15. The MEMS actuator according to claim 1, wherein the actuator body is connected to the frame structure via two actuator arms, the two actuator arms being in a plane and enclosing an angle of substantially 90° or an angle of substantially 180° in the plane.

16. The MEMS actuator according to claim 1, wherein the actuator body has a reflective surface at least in sections.

17. The MEMS actuator according to claim 16, wherein the reflective surface is in the form of a micromirror.

18. A method of producing the MEMS actuator according to claim 1 comprising the steps of: etching of a substrate to form a structure, applying at least one layer comprising an actuator material to provide an actuator arm comprising two or more actuator sections, and etching of the substrate to expose the actuator arm, so that the actuator arm comprising the two or more actuator sections is connected at a first end to a frame structure formed by the substrate and at a second end to an actuator body, the actuator sections being aligned substantially perpendicular to a longitudinal axis of the actuator arm, so that a movement of the actuator body can be effected by actuating the actuator sections to effect lateral bendings.

19. The method of claim 18, wherein the first etching of the substrate forms a meander structure.

20. The method of claim 18, wherein the first etching of the substrate is started from a front side and wherein the second etching of the substrate is started from a rear side.

21. The method according to claim 18, wherein a meander structure is formed by etching the substrate, wherein regions of the meander structure of the substrate, which serve to form the two or more actuator sections, are oriented orthogonally to the surface of the substrate.

22. The method of claim 21, wherein the meander structure is formed by etching the substrate from a front side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0143] FIG. 1 Schematic representation of a preferred embodiment of a MEMS actuator

[0144] FIGS. 2 (A) and (B): Schematic representations of a preferred embodiment of a MEMS actuator with an actuator arm for deflection or tilting of the actuator body

[0145] FIGS. 3 (A) and (B): Schematic representation of a further preferred embodiment of a MEMS actuator with an actuator arm for tilting the actuator body about a stationary axis of rotation (fixing means)

[0146] FIG. 4 Schematic representation of a further preferred embodiment of a MEMS actuator with two opposing actuator arms for vertical translation of the actuator body.

[0147] FIGS. 5 (A) and (B): Simulations of preferred embodiments of a MEMS actuator.

DETAILED DESCRIPTION

[0148] FIG. 1 is a schematic representation of a preferred embodiment of a MEMS actuator 1.

[0149] The MEMS actuator 1 comprises a frame structure 3 and an actuator arm 5. The actuator arm 5 is connected at a first end to the frame structure 3 and at a second end to an actuator body 9. Further, the actuator arm 5 comprises a meander structure comprising actuator sections 7, wherein the actuator sections 7 are oriented substantially perpendicular to a longitudinal axis of the actuator arm 5. Furthermore, the actuator arm 5 comprises at least one layer of an actuator material (not shown), such that a movement of the actuator body 9 can be effected by actuating the actuator sections 7.

[0150] The MEMS actuator 1 advantageously achieves particularly high deflections, in particular in the form of high tilting angles of the actuator body 9. The advantageous achievement of high tilting angles of the actuator body 9 is made possible in particular by the design of the actuator arm 5, in particular by the meander structure comprising actuator sections 7 which are oriented substantially perpendicular to the longitudinal axis of the actuator arm 5.

[0151] The meander structure results in a greater distance and thus a higher moment (product of force and displacement) and consequently also a higher deflectability of the actuator body 9, in particular in the form of a higher tilt angle.

[0152] The beneficial effect of achieving higher deflections of the actuator body 9, in particular higher tilt angles, is useful for a variety of applications. For example, the MEMS actuator 1 is particularly well suited for the movement and/or tilting of micromirrors. Advantageously, the MEMS actuator 1 can be operated with a variety of modes of action. Further, advantageously, a potential user of the preferred MEMS actuator 1 can select an operating principle from a plurality of physical principles, for example, actuation by an electrical or thermal signal, to effect movement of the actuator body 9. The use of an actuator arm 5 with a meander structure to move the actuator body 9 is thus not limited to certain actuator principles.

[0153] Furthermore, the MEMS actuator 1 is characterized by a process-efficient producibility. The MEMS actuator 1 can be provided with common methods of microsystem and/or semiconductor technology, in particular the structuring of the meander structure as well as the design of the actuator arm 5. It is particularly advantageous that the MEMS actuator 1 can be produced from a substrate and thus within a single process sequence. For example, components such as the frame structure 3, the actuator arm 5 comprising actuator sections 7 and/or the actuator body 9 can be formed from a substrate.

[0154] FIGS. 2 (A) and (B) is a schematic representation of a preferred MEMS actuator 1 with an actuator arm 5 and its use for a deflection or tilting of the actuator body 9. FIGS. 2 (A) and (B) shows two phases of a tilting of the actuator body 9. In FIG. 2 (A) the actuator body is tilted in the direction of a front side (“upwards”), while in FIG. 2 (B) the actuator body 9 is tilted in the direction of a rear side (“downwards”). Here, high deflections of the actuator body 9, in particular high tilting angles, are obtained by actuating the actuator sections 7. The actuator body 9 can be tilted by at least 10°, preferably by at least 20°, particularly preferably by at least 40°, especially preferably by at least 60°. Since the actuator body 9 is not fixed, the tilting or rotation of the actuator body 9 is accompanied by a vertical translation out of the plane.

[0155] If such a translational movement is not desired, it may be preferable to restrict the (translational) degree of freedom of the actuator body 9 by means of a fixing element.

[0156] FIGS. 3 (A) and (B) shows a schematic representation of a preferred embodiment of a MEMS actuator 1, which has a fixing element 11 connected to the actuator body 9. The fixing element 11 prevents a translation of the actuator body 9 in a vertical direction, so that the actuator body 9 can be tilted along a substantially stationary pivot point and/or a pivot axis by applying the control signal. Analogous to FIGS. 2 (A) and (B), in FIG. 3A the actuator body 9 is tilted in the direction of a front side, while in FIG. 3 (B) the actuator body 9 is tilted in the direction of a rear side. In contrast to the embodiment of FIGS. 2 (A) and (B), however, there is no superimposed vertical translational movement. The adjustment of the tilting is obtained by fixing element 11.

[0157] Furthermore, a mechanically flexible connector 13 is present at the first end of the actuator arm 5, which is connected to the frame structure 3. Due to the mechanically flexible connector 13, there is advantageously a reduced mechanical resistance at the first end and thus at the connection point of the actuator arm 5 with the frame structure 3, so that the movement of the actuator body 9 takes place with particularly low mechanical resistance. In addition to flexibility, a mechanically flexible connector 13 is preferably characterized by elastic properties in order to ensure a restoring force to a preferred position. Preferably, a mechanically flexible connector 13 can be a MEMS spring.

[0158] FIG. 4 illustrates another preferred embodiment of a MEMS actuator 1.

[0159] Here, the MEMS actuator 1 comprises an actuator body 9 which is connected to the frame structure 3 via two actuator arms 5. The two actuator arms 5 are present in a plane and comprise an angle of substantially 180°. The attachment of two actuator arms 5, in particular along a plane within an angular range of 180°, allows in particular in an efficient way a deflection of the actuator body 9 out of the plane. The attachment of two actuator arms 5 of substantially 180° to each other is characterized by an essentially horizontal extension of the actuator arms 5, with the actuator body 9 being present in the center.

[0160] Furthermore, a mechanically flexible connector 13 is present at both the first end and the second end of the actuator arms 5, so that the deflection and/or movement of the actuator body 9 is facilitated during actuation.

[0161] In FIGS. 5 (A) and (B) simulations of the MEMS actuator 1 are shown, in particular during a deflection of the actuator arm 5. The simulation results shown are based on a finite element method.

[0162] In FIG. 5 (A) the actuator arm 5 from FIG. 2 is simulated without the presence of the actuator body 9. Here an actuator arm 5 with a meander structure and 8 actuator sections is shown, which is fixed at a first end (on the left in FIG. 5 (A)) to a frame structure (not shown). The second end of the actuator arm—to which an actuator body can be attached—is not fixed. In the simulated movement, the second end is deflected or translated in positive y-direction (vertical direction) and negative x-direction (horizontal) while tilting occurs. The fixing at the first end is shown on the left at the blue end (displacement=0). The tilt angle here is approx. 8°.

[0163] From the simulation, it can be seen that during actuation, the individual actuator sections are displaceable, especially at vertical end-side sections of the actuator sections. Consequently, the mechanical resistance of the actuator arm, in particular of the actuator sections, is lower than if the actuator arm were provided by a flat or straight structure, so that high deflections can be achieved.

[0164] In FIG. 5 (B) a MEMS actuator 1 is simulated according to the preferred form of FIG. 4. The modelled actuator arm 5 is fixed with its first end (displacement=0). An actuator body 9 can be attached to its second end, which is also held on an opposite side by a second actuator arm 5 as illustrated in FIG. 4. The vertical displacement of the actuator body 9 is approx. 10 μm in the y-direction in the simulation.

BIBLIOGRAPHY

[0165] Algamili, Abdullah Saleh, et al. “A review of actuation and sensing mechanisms in mems-based sensor devices.” Nanoscale research letters 16.1 (2021): 1-21. [0166] Wang, Dingkang, Connor Watkins, and Huikai Xie. “MEMS mirrors for LiDAR: a review.” Micromachines 11.5 (2020): 456. [0167] Katal, Goldy, Nelofar Tyagi, and Ashish Joshi. “Digital light processing and its future applications.” International journal of scientific and research publications 3.1 (2013): 2250-3153. [0168] Lee, Benjamin. “Introduction to ±12 degree orthogonal digital micromirror devices (dmds).” Texas Instruments (2008): 2018-02. [0169] Holmström, Sven TS, Utku Baran, and Hakan Urey. “MEMS laser scanners: a review.” Journal of Microelectromechanical Systems 23.2 (2014): 259-275. [0170] Pang, Yajun, et al. “Design Study of a Large-Angle Optical Scanning System for MEMS LIDAR.” Applied Sciences 12.3 (2022): 1283.

REFERENCE LIST

[0171] 1 MEMS actuator [0172] 3 Frame structure [0173] Actuator arm [0174] 7 Actuator section [0175] 9 Actuator body [0176] 11 Fixing element [0177] 13 Connector