MEMS with synchronous movable elements

Abstract

A MEMS comprises a substrate having a cavity arranged in the substrate and a plurality of movable elements arranged in the cavity, which elements are designed to interact with a fluid arranged in the cavity, wherein a movement of the fluid by a movement of the movable elements are causally related. The plurality of movable elements are formed in an electrically active manner and are connected electrically parallel to one another via an electric conduction path with a common signal reference. The MEMS is designed to adapt to one another propagation time differences between the common signal reference, and also the conduction paths of different movable elements in order to synchronise movements of the movable elements by way of an electric signal provided at the signal reference and / or to synchronise electric signals generated by the movable elements by way of the movement at the place of the signal reference.

Description

[0001] MEMS with synchronous moving elements

[0002] Description

[0003] The present invention relates to a MEMS with synchronous movable elements and to a method for operating a MEMS. The present invention particularly relates to MEMS with electrically synchronous fins or movable elements.

[0004] In MEMS devices used to move a fluid, such as in sound generators, as well as in MEMS devices used to detect or sense movement in a fluid, such as in a microphone, there are designs in which movable elements are electrically connected in parallel to move or be moved. For optimal operation, it is desirable to avoid distortions and deviations between the movements.

[0005] WO 2021 / 144400 A1 discloses a MEMS sound transducer in which the electrodes for controlling the lamellae are connected in parallel. Figure 11 of WO 2021 / 144400 A1 illustrates a preferred electrical contacting of the MEMS loudspeaker with a vibrating membrane based on individual piezoceramics. Figure 11A shows a top view and Figure 11B a side view of a MEMS loudspeaker. The individual lamellae or vertical sections are controlled in parallel via electrode pads, with U-shaped spacers on each side of the lamellae creating a mechanical and electrical connection to the next lamella.

[0006] However, such systems have disadvantages with regard to distortions in the generated signals.

[0007] MEMS with good signal properties in the actuator and / or sensor area would therefore be desirable.

[0008] One object of the present invention is therefore to create MEMS with good signal properties in the actuator and / or sensor area. This object is achieved by the subject matter of the independent patent claims.

[0009] A core concept of the present invention is the recognition that at least part of the differing behavior between moving elements stems from the fact that they are connected to a common signal reference, such as a signal sink or a signal source or a collection point, and that different propagation time differences exist between the signal reference and the respective moving element. According to the invention, it was recognized that compensating or balancing the propagation time differences in order to synchronize the movement of the moving elements or to synchronize the generated electrical signals at the location of the signal reference leads to good signal properties of the generated signals, both in actuator operation and in sensor operation.

[0010] According to one embodiment, a MEMS comprises a substrate with a cavity arranged in the substrate. The MEMS comprises a plurality of movable elements arranged in the cavity, which are configured to interact with a fluid arranged in the cavity, wherein a movement of the fluid and a movement of the movable elements are causally related. The plurality of movable elements are electrically active and electrically connected in parallel to one another via a respective electrical conduction path to a common signal reference.The MEMS is designed to align propagation time differences between the common signal reference on the one hand and the conduction paths of different movable elements on the other hand, to synchronize movements of the movable elements generated by an electrical signal provided at the signal reference and / or to synchronize electrical signals generated by the movable elements by the movement at the location of the signal reference.

[0011] According to one embodiment, a method for operating a MEMS comprising a substrate and a cavity arranged in the substrate, as well as a plurality of actively formed movable elements arranged in the cavity, comprises moving the plurality of movable elements arranged in the cavity such that the movable elements interact with a fluid arranged in the cavity, so that a movement of the fluid and a movement of the movable elements are causally related. The method is carried out such that the plurality of movable elements are electrically connected in parallel to one another via a respective electrical conduction path with a common signal reference.Propagation time differences between the common signal reference, on the one hand, and the conduction paths of different moving elements, on the other hand, are adjusted to synchronize movements of the moving elements generated by an electrical signal provided at the signal reference and / or to synchronize electrical signals generated by the moving elements at the location of the signal reference. Further advantageous embodiments are the subject of dependent patent claims.

[0012] Particularly preferred embodiments of the present invention are explained below with reference to the accompanying drawings. They show:

[0013] Fig. 1 is a schematic side sectional view of a MEMS according to an embodiment;

[0014] Fig. 2a is a schematic plan view of sections of conduction paths according to embodiments;

[0015] Fig. 2b is a schematic representation of an embodiment for adapting the electrical impedance of conduction paths to each other;

[0016] Fig. 2c is a schematic block diagram of a MEMS according to an embodiment in which the signal reference of a MEMS is coupled to a signal source for providing a signal voltage;

[0017] Fig. 3 is a schematic equivalent circuit diagram of a MEMS according to an embodiment; and

[0018] Fig. 4 is a schematic flow diagram of a method according to an embodiment.

[0019] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0020] The following embodiments are described in conjunction with numerous details. However, embodiments may also be implemented without these detailed features. Furthermore, for clarity, embodiments are described using block diagrams instead of detailed representations. Furthermore, details and / or features of individual embodiments may be readily combined with one another, unless explicitly described otherwise.

[0021] The following embodiments relate to microelectromechanical systems (MEMS) in which actuator and / or sensor operation is provided. In the case of actuator operation, forces can be generated using electrical signals to deflect movable elements. Examples of this are described in DE 10 2017 206 766 A1 and WO 2022 / 117197 A1, which are particularly suitable for the use of the present invention, but nevertheless do not limit the invention. The cited publications are incorporated in their entirety into the present patent application in this regard.

[0022] Movable elements of a MEMS can move parallel to a substrate plane or wafer surface, which is also referred to as in-plane movement. Alternatively or additionally, movable elements can also move perpendicular to this plane, i.e., out-of-plane, which can be implemented independently and combinatorially within the scope of the invention described herein.

[0023] In an actuator mode, piezoelectric, electrostatic, electrodynamic, thermomechanical, or other actuators can be used to convert an electrical signal into a force for the moving element. Examples of actuators include pumps, sound generators, or loudspeakers. In a sensor mode, a force acting on the respective moving element and causing it to deflect can be converted into an electrical signal. Examples of this include microphones or pressure sensors.

[0024] Since MEMS devices typically have small travel ranges compared to macroscopic assemblies, there is sometimes a desire to use multiple moving elements to generate corresponding signal amplitudes or effective forces. In actuator operation, for example, the moving elements can be connected in parallel and driven together. In sensor operation, the moving elements can also be connected in parallel and evaluated together.

[0025] Embodiments of the present invention relate in particular to MEMS that have actively movable elements that are mechanically and electrically connected in parallel and have different path resistances or signal line impedances due to different distances from the voltage source or signal sink. This can lead to the signal voltage amplitude reaching the actively movable elements with a delay along the course of an exponential function, which is referred to as an RC low-pass filter behavior.

[0026] The actively moving elements that are closest to the voltage source in the circuit are always the first to reach the specified signal voltage. The other, more distant moving elements follow the signal voltage with a time delay depending on their position. The described time offset and the varying quality of the signal voltage when controlling the individual active components can cause undesirable component behavior, such as reduced transduction or asynchrony.

[0027] In a sound generator, such as a micro loudspeaker, this may lead to reduced deflection of individual elements and thus lower sound output or a phase shift, which in turn can lead to undesirable artifacts and deviations in the sound and / or limit component function, for example through pull-in in electrostatic systems. For example, those actuators located closer to the signal voltage source may go into pull-in more frequently. Due to the sudden increase in capacitance, the voltage across the actively moving element decreases. Furthermore, the varactor effect also increases the delay time, which becomes more pronounced the greater the change in the electrical capacitance of the drive due to the control.

[0028] Such effects occur in actively moving elements, for example, in MEMS microspeakers, MEMS pumps, MEMS valves, MEMS varactors, and / or MEMS ultrasonic components. In addition to the described actuators, corresponding sensors can also be improved using the embodiments described herein. Embodiments enable synchronous operation of moving elements in a MEMS transducer.

[0029] The present embodiments overcome the disadvantage of previously known solutions, which consists in the fact that actuators connected in parallel have different line lengths or mismatched line resistances and / or line impedances to the signal source or signal sink. Actuators with the shortest line length or the smallest line resistance thus reach the specified signal voltage first. According to the present embodiments, a state is at least approximated in which the same signal voltage is applied to all active elements simultaneously or in which the signals are received from all active elements simultaneously at a signal reference.

[0030] Embodiments of the present invention are directed to providing a MEMS converter with a plurality of synchronously operating elements. This reduces or prevents a delay in the signal voltage at the converter elements and / or a delayed arrival at a signal reference, as well as undesirable behavior, such as pull-in of the elements located closer to the signal voltage source.

[0031] Fig. 1 shows a schematic side sectional view of a MEMS 10 according to one embodiment. In other embodiments described herein, however, the discussions are also readily applicable to a top view of a MEMS. The MEMS 10 comprises a substrate 12 with a cavity 14 arranged in the substrate 12. The substrate 12 can be formed in a single layer or in multiple layers, for example by etching out the cavity 14 and / or by connecting several wafers to one another, for example by means of a bonding process. The substrate 12 can, for example, comprise a semiconductor material, for example comprising monocrystalline or polycrystalline silicon, although other MEMS-compatible semiconductor materials can also be readily used.

[0032] Electrical connections in the substrate 12 and / or the MEMS 10 can be obtained by doping in semiconductor materials and / or by using other conductive materials, such as metal materials.

[0033] The MEMS 10 comprises a plurality of movable elements 16i and 162 arranged in the cavity 14, wherein the number of movable elements can easily be greater than 2, for example at least 3, at least 5, at least 10 or more.

[0034] The movable elements 161 and 162 are designed to interact with a fluid 18 arranged in the cavity, wherein a movement of the fluid 18 and a movement 22i of the movable element 161 and a movement 222 of the movable element 162 are causally related. For example, a movement of the fluid 18 can lead to the movements 22i and 222, for example when the MEMS 10 is operated as a sensor. Alternatively or additionally, an active generation of the movements 22i and 222, for example by means of electrical signals, can lead to a movement of the fluid 18, for example when the MEMS 10 is used as an actuator, for example as a sound generator. The movable elements 161 and 162 are actively formed and electrically connected in parallel to one another via a conduction path 24i, 242 to a common signal reference 26. The signal reference 26 may, but does not necessarily, represent an active circuit for generating or providing or for receiving orEvaluating electrical signals. The signal reference 26 can also include a coupling point, a connection point, or an interface for contacting an external circuit for such purposes. The signal reference 26 can, for example, be a current source or voltage source, include such a source, or be coupled to such a source in order to deliver an electrical signal via the conduction path 24i to the movable element 161 and an electrical signal via the conduction path 242 to the movable element 162. The conduction paths 24i and 242 can optionally have a common section 28, but can also be connected in parallel to one another directly at the signal reference 26.

[0035] The propagation times 32i of the conduction path 24i and 322 of the conduction path 242 can be influenced by several parameters. One of the parameters is, for example, a line length, another an ohmic resistance, which in turn can be influenced by the line length but also by a line cross-section. Another parameter is capacitive coupling, which can also result from a periphery of the respective conduction path 24i and / or 242. The MEMS 10 is designed to equalize the propagation time differences 32i between the signal reference 26 and the movable element 161, on the one hand, and between the signal reference 26 and the movable element 162. In other words, measures can be taken in the MEMS 10 to equalize the propagation times 32i and 322 and thus keep the propagation time differences between the propagation times 32i and 322 to a minimum.In an actuator operation, this can achieve that an electrical signal provided at the signal reference 26 is synchronized to generate the movements 22i and 222 of the movable elements 161 and 162. In an alternatively or additionally implemented sensory operation, this can achieve that electrical signals generated by the movable elements 161 and 162 by the movement 22i and 222, respectively, are synchronized at the location of the signal reference 26.

[0036] The movements 22i and 222 can be arranged in the same direction or along different spatial directions, wherein a parallel alignment of the movements 22i and 222 is particularly advantageous. The movements 22i and 222 can be arranged in-plane and / or out-of-plane. Furthermore, the cavity 14 is possibly, but not necessarily, sealed from the environment of the substrate 12. Embodiments provide that openings in the substrate 12 connect the cavity 14 to the environment, and the fluid 18 can flow into and / or out of the cavity 14 through such openings.

[0037] According to embodiments, the movable elements are arranged at a different distance 34i, 342 from the signal reference 26 in the MEMS. This can result, for example, from the signal reference 26 being arranged at a specific location in the MEMS 10 or being connectable to the MEMS 10 at a specific location, such as in a case where the signal reference 26 comprises an external circuit that can be coupled to the MEMS 10. Movable elements 16i and 162 positioned at different locations in the MEMS 10 can have a different distance from this location. In known circuits, this can lead to the use of conduction paths 24i and 242 with different propagation times 32i and 322, which is addressed by the embodiments described herein. For this purpose, embodiments provide different possibilities, which can be used individually or in combination with one another.

[0038] Thus, embodiments provide that the conduction paths 24i and 242 have a substantially identical electrical connection characteristic of the movable elements 161 and 162 to the signal reference 26. Such a connection characteristic can, for example, mean or include an electrical conductivity and / or an electrical impedance, meaning that the conduction paths 24i and / or 242 can be formed such that a substantially identical or as precisely as possible matching connection characteristic is present, for example, an approximately identical electrical conductivity and / or an approximately identical electrical impedance. Deviations from an exact match are possible without problems within the scope of the embodiments described herein, for example, within a tolerance range of ±20%, ±10%, or ±5%, preferably less.

[0039] Compared to a theoretical initial state in which the movable elements 161 and 162 have a different distance from the signal reference 26, at least one of the conduction paths 24i and 242 can be changed. Thus, to adapt the electrical connection characteristics, at least one of the conduction paths can be provided with a conduction-path-specific meandering of a course of at least one of the conduction paths. Alternatively or additionally, a conduction-path-specific cross-section change can be provided. This can apply to the entire conduction path or only to sections. Thus, a local reduction in the conduction cross-section can produce a local increase in a conduction capacitance and / or a conduction path resistance. Alternatively or additionally, one of the conduction paths 24i or 242 can be provided with a smaller or larger conduction cross-section than the other conduction path.Alternatively or in addition to these measures, the conduction paths may comprise a conduction-path-specific capacitive coupling between the conduction path and the substrate to adapt the electrical connection characteristics. Such a coupling may exist, for example, to adjacent layers or wafers, for example, to a cover wafer and / or base wafer that may delimit a cavity 14 provided in a device wafer.

[0040] According to embodiments, the conduction paths 24i and 242 can be configured such that they have substantially the same electrical conductivity. This can be achieved, for example, by designing shorter conduction paths with a larger cross-section than longer conduction paths. Alternatively or additionally, this can also be achieved by extending conduction paths for movable elements that are arranged closer to the signal reference 26, such as the conduction path 24i, by additional line lengths, so that the conduction paths 24i and 242 have an equalized line length. This can possibly be at least approximately identical, but this is not necessary in view of other measures, such as additional changes in the line cross-section or the like, since the measures, individually but also in combination, are aimed at equalizing the propagation time differences 32i and 322.

[0041] According to one embodiment, the movable elements 16i and 162 have a different distance from the signal reference 26, but at the same time have a substantially equal line length.

[0042] Fig. 2a shows a schematic top view of sections of the conduction paths 24i and 242, as they can be used, for example, in the MEMS 10. With reference to Fig. 1, the movable element 161, which is connected to the signal reference 26 via the conduction path 24i, is arranged at a shorter distance 34i than the movable element 162, which is arranged at a distance 342. The conduction path 24i can have an additional conduction path section 36 in order to match a length of the conduction paths 24i and 242 to one another. The additional distance 36 can preferably be arranged in a meandering manner, since this allows inductances to be kept low. Additional sections 36 can be provided at one or more locations along the conduction path 24i. This does not fundamentally rule out additional sections 36 in the conduction path 242 either.It should also be noted that, for the sake of simplicity, in the exemplary embodiments described herein, it is assumed that the conduction paths of movable elements arranged closer to the signal reference 26 are extended in order to achieve an equalization of the conduction path lengths. However, due to layout-specific conditions in the MEMS 10, it may also be the case that movable elements arranged closer to the signal reference 26 are to be connected to the signal reference 26 via a comparatively longer conduction path length, so that equalization can then be achieved for the conduction path that has a shorter direct distance but a longer conduction length.

[0043] According to one embodiment, the movable elements 161 and 162 can be arranged at a different distance 34i and 342 from the signal reference 26 in the MEMS 10. The conduction paths 24i and 242 can nevertheless have a substantially equal conduction length, for example within a tolerance range of ±20%, ±10%, ±5%, or less. The conduction paths 24i and 242 can both have a respective possibly meandering conduction path section, wherein the different additional and possibly meandering conduction path sections have a first electrical impedance and a second electrical impedance, respectively, wherein the additional conduction path sections result in an overall impedance of the first conduction path 24i and an overall impedance of the second conduction path 242 substantially matching.This means that a sum impedance of the actual conduction path length and additional sections leads to a substantially identical conduction path impedance within the stated tolerances, whereby additional sections are optional and may only be provided for those conduction paths that are significantly shorter than other conduction paths, so that at least one of the conduction paths can remain in the MEMS 10 without additional sections.

[0044] This means that the impedance matching by means of meandering can be designed differently in different line path sections, but that the remaining path sections also have a different impedance due to the different lengths, so that the sum of the impedances from meandering and remaining path length can match the other line paths overall.

[0045] According to embodiments, it can be provided that the electrical conduction paths have a substantially identical electrical impedance. According to one embodiment thereof, in the case of different conduction paths, a path-specific cross-sectional change of at least one conduction path and / or a path-specific meandering conductor track section can be provided to equalize the electrical impedance. Fig. 2b shows one possibility for adapting the electrical impedance of the conduction paths 24i and 242 to one another. For example, the comparatively closer movable element 161 can be connected to the signal reference 26 via the conduction path 24i with a width 38i, while the comparatively further away movable element 162 can be electrically connected to the signal reference 26 via the conduction path 242 with a width 382.This can be particularly suitable for MEMS structures where the layer thickness of electrical paths in a MEMS wafer is uniform. Alternatively or additionally, the widths 38i and 382 can also refer to another spatial direction, such as a layer thickness, whereby combinations of these are also possible. Each of the spatial directions allows for the adjustment of a conductive path cross-section, either individually or in combination with another spatial direction.

[0046] In addition to a path-specific cross-sectional change or a path-specific conductor cross-section, a path-specific meandering conductor section can be arranged, as described. Different additional conductor path sections can differ from one another with regard to the number of meanders, the length of the meanders, and / or the shape or spatial density of the meanders. Alternatively or additionally, a path-specific capacitive coupling to the substrate can also be arranged to maintain a substantially equal electrical impedance between different conductor paths.

[0047] Fig. 2c shows a schematic block diagram of a MEMS 20 according to an embodiment, in which the signal reference 26 is coupled to a signal source 42 for providing a signal voltage 44. The signal source 42 can be part of the MEMS 20 or provided as an external component. A connection characteristic 46i of the conduction path 24i can be at least approximately matched to a connection characteristic 462 of the conduction path 242 by arranging the section 36 in the conduction path 24i.

[0048] In other words, Fig. 2c shows a system with the same control characteristics for the electrodes and movable elements I61, 162 to be connected in parallel.

[0049] Fig. 3 shows a schematic equivalent circuit diagram of a MEMS 30 according to an embodiment. The MEMS 30 has, for example, a signal source 42, which can provide the signal reference 26 of the MEMS 10 or is at least coupled thereto. In other words, the signal reference 26 of the MEMS 10 can be configured for coupling to a signal source, such as the signal source 42, for controlling the movable elements 161 to 163. The movable elements 161 to 163 can be connected in parallel to one another, so that a respective track resistance R1, R2 can comprise at least part of a total track resistance of a subsequent conduction path 242 or 24a. For example, the conduction path 242 can comprise the resistors R1 and R2, and the conduction path 24a can additionally comprise the track resistance R3.It is also shown that different capacitive couplings C1, C2, and C3 can be effective for different movable elements I61, I62, and I63, wherein, in particular, the capacitances C1 to C3 can cause effects that depend on a signal voltage 44 of the signal source 42, for example, a frequency thereof. It is clear that by providing the measures described herein, individually or in combination, an adjustment of the behavior of the movable elements I61 to I63 can be achieved, which is advantageous.

[0050] According to one embodiment and with reference to a layered structure of the MEMS described herein, a respective conduction path can have a capacitive coupling to at least one layer of the substrate 12, which contributes to a conduction path-specific impedance. The capacitive couplings can be individually adapted to equalize an acting impedance in different conduction paths. This can be implemented, for example, by applying conductive tracks, possibly of the same length and / or cross-section, and arranging them on different types of insulators or dielectric layers, which can have different dielectric constants from one another. This can result in a different capacitive coupling to the substrate.Alternatively or additionally, capacitive coupling can also be adjusted by varying the shape, such as the size of an area that becomes capacitive. This does not preclude combinatorial measures with regard to the conductor cross-section and / or possible meandering.

[0051] According to one embodiment, a MEMS described herein, such as MEMS 10 and / or 30, is configured as a sensor or as an actuator. Possible actuators include sound generators that can be operated, for example, in the infrasound, acoustic, and / or ultrasonic ranges, such as loudspeakers. The movable elements 16 can be configured for the synchronized generation of a sound wave in the fluid. In other words, Fig. 3 shows a MEMS transducer with electrodes that are supposedly connected in parallel but are actually connected in series. The state illustrated here is readily applicable to elements that are actually connected in parallel according to embodiments.

[0052] Fig. 4 shows a schematic flow diagram of a method 400 according to an embodiment. A step 410 includes moving the plurality of movable elements of a MEMS arranged in the cavity such that the movable elements interact with a fluid arranged in the cavity, so that a movement of the fluid and a movement of the movable elements are causally related.

[0053] Features 420 of method 400 ensure that the method is carried out such that the plurality of movable elements are electrically connected in parallel to one another via a respective electrical conduction path to a common signal reference. The method is carried out such that propagation time differences between the common signal reference, on the one hand, and the conduction paths of different movable elements, on the other hand, are aligned to one another in order to synchronize movements of the movable elements generated by an electrical signal provided at the signal reference and / or to synchronize electrical signals generated by the movement of the movable elements at the location of the signal reference. The alignment can be provided both within the MEMS, but can also be implemented, for example, via additional interconnection of a signal source or signal sink to be coupled externally to the MEMS.

[0054] Embodiments of the present invention achieve the objective of providing high-quality signals, among other things, by connecting the MEMS converter elements and movable elements in parallel, each having the same electrical connection characteristics, such as line lengths or the like, to the energy source or energy sink. If necessary, the supply paths to the active elements can be geometrically targeted and balanced according to their conductivity, which also includes the parasitic impedance.

[0055] Embodiments of the present invention relate to MEMS, which can be characterized by a multi-element MEMS converter structure in which all active elements of the converter are electrically interconnected such that the terminals of the individual elements with the same name are connected to a pole of the signal source via identical line lengths or impedances. In this context, identical connection is understood to mean a connection with the same potential.

[0056] According to some embodiments, the impedance is adjusted along the line length by a meandering pattern. According to alternative or additional configurations, the impedance is adjusted by a cross-sectional change, which can be implemented by etching from above or from below, for example, as an "indentation." According to further embodiments, which can be used alternatively or additionally, the impedance can also be introduced as a capacitive load through the connection to the cover wafer.

[0057] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0058] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims

Patent claims 1. A MEMS comprising: a substrate (12) having a cavity (14) arranged in the substrate (12); a plurality of movable elements (I61-I63) arranged in the cavity (14) and configured to interact with a fluid (18) arranged in the cavity (14), wherein a movement of the fluid (18) and a movement (22) of the movable elements (I61-I63) are causally related; wherein the plurality of movable elements (I61-I63) are formed to be electrically active; and are electrically connected in parallel to one another via a respective electrical conduction path (24) to a common signal reference (26); wherein the MEMS is designed to match propagation time differences between the common signal reference (26) on the one hand and the conduction paths (24) of different movable elements on the other hand in order to synchronize movements (22) of the movable elements (16i-163) generated by an electrical signal provided at the signal reference (26);and / or to synchronize electrical signals generated by the movable elements (I61-I63) by the movement (22) at the location of the signal reference (26); 2. MEMS according to one of the preceding claims, wherein the movable elements (I61-I63) are arranged at a different distance (34) from the signal reference (26) in the MEMS.

3. MEMS according to claim 1 or 2, wherein the conduction paths (24) have a substantially identical electrical connection characteristic of the movable elements (I61-I63) to the signal reference (26).

4. MEMS according to claim 3, wherein the electrical connection characteristic comprises an electrical conductivity and / or an electrical impedance.

5. MEMS according to claim 3 or 4, wherein the conduction paths (24) for adapting the electrical connection characteristics comprise at least one of a conduction path-specific meandering of a course of conduction paths (24); a conduction path-specific cross-sectional change; and / or a conduction path-specific capacitive coupling between the conduction path (24) and the substrate (12).

6. MEMS according to one of the preceding claims, wherein the conduction paths (24) have substantially the same electrical conductivity.

7. MEMS according to one of the preceding claims, wherein the movable elements (I61-I63) are arranged at a different distance (34) from the signal reference (26) in the MEMS; and the conduction paths (24) have a substantially equal conduction length.

8. MEMS according to claim 7, wherein a conductor track of the first movable element (I61), which is arranged opposite a second movable element (I62) at a smaller distance (34) from the signal reference (26), has an additional and meandering conductor path section (36) in order to adjust a length of the conductor paths (24).

9. MEMS according to one of the preceding claims, wherein the movable elements (I61-I63) are arranged at a different distance (34) from the signal reference (26) in the MEMS; and the conduction paths (24) have a substantially equal conduction length; wherein at least a first conduction path (24i) has a first meandering conduction section and a second conduction path (242) has a second meandering conduction section; wherein the first meandering conduction path section has a first electrical impedance and the second meandering conduction path section has a different second electrical impedance, and a sum impedance of the first conduction path (24i) and a sum impedance of the second conduction path (242) substantially match.

10. MEMS according to one of the preceding claims, wherein the electrical conduction paths (24) have a substantially equal electrical impedance.

11. MEMS according to claim 10, wherein different conduction paths (24) for equalizing the electrical impedance have a path-specific cross-sectional change of at least one conduction path (24) and / or a path-specific meandering conductor track section and / or a path-specific capacitive coupling with the substrate (12).

12. MEMS according to one of the preceding claims, wherein a respective conduction path (24) has a capacitive coupling to at least one layer of the substrate (12) that contributes to a conduction path-specific impedance; wherein the capacitive couplings are individually adapted to match an effective impedance in different conduction paths (24).

13. MEMS according to one of the preceding claims, wherein the signal reference (26) is arranged to be coupled to a signal source (42) for controlling the movable elements (I61-I63).

14. MEMS according to claim 13, comprising the signal source (42).

15. MEMS according to claim 13 or 14, which is configured as a sound generator; wherein the movable elements (161-163) are configured for the synchronized generation of a sound wave in the fluid (18).

16. A method (400) for operating a MEMS with a substrate; with a cavity arranged in the substrate and with a plurality of movable elements arranged in the cavity and actively formed; the method comprising: Moving (410) the plurality of movable elements arranged in the cavity such that the movable elements interact with a fluid arranged in the cavity such that a movement of the fluid and a movement of the movable elements are causally related; such that the plurality of movable elements are electrically connected in parallel to one another via a respective electrical conduction path with a common signal reference; and such that propagation time differences between the common signal reference, on the one hand, and the conduction paths of different movable elements, on the other hand, are matched to one another in order to synchronize movements of the movable elements generated by an electrical signal provided at the signal reference; and / or to synchronize electrical signals generated by the movable elements by the movement at the location of the signal reference.

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