EP4255844A1

EP4255844A1 - Mems having lid drive and method for operation thereof

Info

Publication number: EP4255844A1
Application number: EP20820367.9A
Authority: EP
Inventors: Sergiu Langa; Bert Kaiser; Anton MELNIKOV; Jorge Mario MONSALVE GUARACAO
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2020-12-03
Filing date: 2020-12-03
Publication date: 2023-10-11
Also published as: WO2022117197A1; TWI848249B; CN116802143A; US20230322546A1; TW202235359A

Abstract

The invention relates to a MEMS component comprising a layer stack having a plurality of MEMS layers arranged in a layer sequence direction. The MEMS component comprises a movable element which is formed in a first MEMS layer and is arranged between a second MEMS layer and a third MEMS layer of the layer stack. A drive device is furthermore provided and has a first drive structure, which is mechanically fixedly connected to the movable element, and a second drive structure, which is mechanically fixedly connected to the second MEMS layer. The drive device is designed to generate a drive force acting on the movable element perpendicular to the layer sequence direction, and the drive force is designed to deflect the movable element.

Description

Top drive MEMS and method of operating the same

description

The present invention relates to a MEMS device and a method of operating the same. The present invention relates in particular to a MEMS with a cover drive for driving a movable element in-plane, ie in the plane.

MEMS converters are known which are formed from a substrate and have limited geometric dimensions or aspect ratios due to the restricted aspect ratio, for example the Bosch method. If the volume of a MEMS component is to be increased, this is possible, for example, by etching it deeper. At the same time, however, it is not possible to realize a small electrode spacing between adjacent electrodes, since this is also increased due to the etching method. Thus, it is at least difficult to develop a transducer which, on the one hand, can interact with a large volume of the surrounding fluid and, in doing so, can apply the necessary force or has correspondingly small electrode spacings.

There is therefore a need for MEMS converters that have a large aspect ratio in order to be able to move large volumes of fluid and at the same time be able to realize small electrode spacings.

It is therefore an object of the present invention to provide MEMS devices with high aspect ratios.

This object is solved by the subject matter of the independent patent claims.

A key idea of the present invention consists in having recognized that an in-plane actuation of a movable element can also be based on an electrode arrangement which is arranged perpendicularly to the direction of movement, which makes it possible to release large movable elements, for example by means of etching, and at the same time to allow small gap distances perpendicular to the direction of movement, since these gap distances can be independent of the etching process used. According to one embodiment, a MEMS component includes a layer stack with a plurality of MEMS layers, which are arranged along a layer sequence direction. Furthermore, a movable element formed in a first MEMS layer is provided, which is arranged between a second MEMS layer and a third MEMS layer of the layer stack. The MEMS component includes a drive device with a first drive structure mechanically fixed to the movable element and a second drive structure mechanically fixed to the second MEMS layer, which makes it possible to apply forces between the two drive structures Drive device is designed to generate a drive force perpendicular to the layer sequence direction on the movable element, wherein the drive force is designed to deflect the movable element, in particular with a component perpendicular to the layer sequence direction, resulting in a rotational movement, a torsional movement and/or may include a translational movement.

According to one embodiment, the first drive structure and the second drive structure are spaced apart by a gap and arranged opposite one another. A dimension of the gap along the layer sequence direction is set by, for example, a bonding process. Bonding processes enable small gap distances, so that high forces can be generated using electrostatic or electrodynamic driving forces, for example.

According to one embodiment, the moveable element is configured to have a plurality of layers connected by a bonding process. This makes it possible to obtain large movable elements and thus also high aspect ratios, so that a large amount of fluid can be moved with the movable element.

According to one exemplary embodiment, the second drive structure is a structured electrode structure with at least one first electrode element and a second electrode element that is electrically insulated therefrom. The MEMS component is designed to apply a first electrical potential to the first electrode element and a second electrical potential that differs therefrom to the second electrode element. The MEMS device is further configured to apply a third electrical potential to the first drive structure to generate the drive force in interaction of the third electrical potential with the first electrical potential or the second electrical potential. This allows, for example, bidirectional and possibly linear Deflection of the movable element in terms of a back and forth movement, which is advantageous.

According to one exemplary embodiment, the first electrode element and the second electrode element are electrically insulated from one another by an electrode gap. When the movable element is in a rest position, it is arranged symmetrically and/or asymmetrically opposite the electrode gap. While an at least regionally symmetrical arrangement enables a deflection even with low electrical voltages and/or a symmetrical deflection, a preferred direction and/or a mechanical pre-deflection can be implemented by means of at least regional asymmetry.

According to one exemplary embodiment, electrodes of the second drive structure have a constant or variable lateral dimension perpendicular to the axial direction along an axial course perpendicular to the layer sequence direction. In other words, the electrodes can provide strips with a variable stripe width, for example. Variable expansion makes it possible to take into account and/or compensate for mechanical stresses that can be triggered by electrode deformation.

According to one exemplary embodiment, the drive device has a third drive structure that is mechanically firmly connected to the third MEMS layer. A first gap is arranged between the first drive structure and the second drive structure and a second gap is arranged between the first drive structure and the third drive structure. The drive device is designed to provide the drive force based on a first interaction between the first drive structure and the second drive structure and based on a second interaction between the first drive structure and the third drive structure. This enables a further increase in the force deflecting the movable element and/or precise movement of the movable element.

According to one exemplary embodiment, the drive device is designed to generate a first drive force component based on the first interaction and a second drive force component based on the second interaction. The MEMS device is configured to receive the first driving force component or interaction and the second to generate the driving force component or interaction in phase or with a phase shift. While an in-phase control can be used, for example, for a translatory displacement of the movable element, a possibly variable but also a constant phase offset can be used for a rotation or tilting or torsion of the movable element.

According to one embodiment, the moveable element is mechanically connected to the third MEMS layer via an elastic region. The movable member is configured to rotate based on the driving force while deforming the elastic portion. This enables targeted configurations of the individual components.

According to one embodiment, an electrode structure is arranged on a side or MEMS layer facing the second MEMS layer and/or on a side or MEMS layer facing the third MEMS layer and forms at least part of the first drive structure. This enables a high degree of variability in the electrical variability of the electrical control.

According to one exemplary embodiment, the movable element is configured on a side facing the second MEMS layer and/or the second MEMS layer on a side facing the movable element in such a way that surface structuring is provided in order to reduce the distance between the movable Element and the second MEMS layer to change locally. This enables a precise adjustment of electrostatic forces based on a changing electrode distance during the movement.

According to one exemplary embodiment, electrodes of the first drive structure and/or electrodes of the second drive structure are arranged and connected interdigitally. This enables a low level of electrical interference fields.

In accordance with one exemplary embodiment, the MEMS component comprises a multiplicity of movable elements which are arranged next to one another in a common MEMS plane and which are coupled to one another fluidically and/or by means of a coupling element. This allows for a high level of moving fluid. According to one exemplary embodiment, a drive structure with at least two connected electrodes arranged next to one another is arranged on each of the movable elements, of which one electrode is connected to a first electrical potential and a second electrode is connected to a second, different electrical potential. Facing electrodes of adjacent movable elements are connected to a combination of the first electric potential and the second electric potential. In other words, electrodes of adjacent movable elements can be driven electrically differently. This enables individual elements to be controlled as required.

According to one embodiment, the movable element is movably arranged in a MEMS cavity. By means of a movement of the movable element, at least one partial cavity of the cavity is alternately enlarged and reduced, with the partial cavity extending locally into the second MEMS layer. By extending the partial cavity into the second MEMS layer, the corresponding MEMS space can be used efficiently.

According to one exemplary embodiment, the movable element has an element length along an axial stretching direction perpendicular to the layer sequence direction. An electrode of the first drive structure has a plurality of electrode segments along the element length. Adjacent electrode segments are electrically connected to one another in an electrically conductive manner by electrical conductors. The electrical conductors have a lower mechanical rigidity than the electrode segments along a direction perpendicular to the element length. As a result, these areas can absorb deformation energy, so that the electrode segments are deformed to a small extent, which has a high level of efficiency.

According to one embodiment, the moveable element is configured to provide interaction with a fluid. This can be done directly via direct contact with the fluid or indirectly, in that mechanical elements provided for fluid interaction are moved by the movable element.

According to one exemplary embodiment, the drive device has a fourth drive structure, which is arranged on a side of the second MEMS layer that faces away from the movable element. Another movable element is adjacent to the fourth Arranged drive structure and forms a stacked arrangement with the movable element. This allows for a high degree of fluid interaction with little chip area occupation by the stacked arrangement.

According to one exemplary embodiment, a method for operating a MEMS component includes driving two drive structures arranged one behind the other along a layer sequence direction along which a multiplicity of MEMS layers of the MEMS component are arranged, and generating a drive force on a movable element of the MEMS device perpendicular to the layer sequence direction by driving to deflect the MEMS device.

According to one exemplary embodiment, the method is designed in such a way that a symmetrical and/or linear deflection of the movable element is controlled by means of adjacent electrode elements of the drive device, which are electrically insulated from one another by an electrode gap, by the electrode elements being symmetrical about a reference potential on average over time be controlled with respect to the applied potentials.

According to one exemplary embodiment, the deflection of the movable element is controlled asymmetrically on average over time along an actuation direction with respect to an opposite direction, ie, controlled asymmetrically. This can be used, for example, to compensate for mechanical pre-deflections or mechanical asymmetries.

Further advantageous configurations are the subject matter of further dependent patent claims.

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

1 shows a schematic side sectional view of a MEMS component according to an embodiment;

2a shows a schematic side sectional view of a section of a MEMS component according to an embodiment; 2b-d schematic side sectional views of different deflection states of the MEMS component from FIG. 2a according to exemplary embodiments;

3a shows a schematic side sectional view of a MEMS device according to an embodiment having a topography in a bottom wafer and/or a cap wafer;

3b-d schematic side sectional views of movable elements according to exemplary embodiments;

4a shows a schematic side sectional view of a movable element with an electrode structure according to an embodiment;

4b shows a schematic side sectional view of a movable element with a structured electrode structure according to an embodiment;

5a shows a schematic plan view of a part of a MEMS component to illustrate an interdigital interconnection of electrodes according to an embodiment;

5b shows a schematic plan view of a part of a MEMS component to illustrate an interdigital interconnection of structured electrodes according to an embodiment;

6 shows a schematic side sectional view of a part of a MEMS component according to an embodiment with four movable elements according to an embodiment;

7a-c schematic side sectional views of a MEMS component according to an embodiment and different implementations of electrical contacting thereof;

8a-c side sectional views of a MEMS-based sound transducer according to an embodiment and in three deflection states; 9 shows a schematic perspective view of parts of a MEMS component with movable elements clamped on both sides; according to one embodiment;

10 is a schematic perspective view of parts of a MEMS device with cantilevered movable elements; according to one embodiment;

11 shows a schematic perspective view of a part of a MEMS component according to an embodiment which can have both openings and interdigital electrodes;

12a-c top views of areas of alternative configurations of a unit cell for MEMS components according to exemplary embodiments;

13 is a schematic side sectional view of parts of a MEMS device according to an embodiment in which a movable element is formed in an H-shape;

14 is a schematic side sectional view of a MEMS device according to an embodiment in which the movable element is formed in a block shape;

15a-c schematic side sectional views of stacked MEMS according to exemplary embodiments;

16a-c each show a side sectional view of an alternative drive with linear deflection behavior based on a cover drive according to exemplary embodiments;

17a-c Complementary implementation of the alternative drive according to exemplary embodiments compared to FIGS. 16a-c;

18a shows a schematic plan view of a MEMS component according to an embodiment, which is connected to the substrate opposite a drive structure via an elastic region; 18b is a schematic side sectional view of the MEMS device of FIG

18a; and

19 shows a schematic flow diagram of a method according to exemplary embodiments described herein.

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

Exemplary embodiments described below are described in connection with a large number of details. However, example embodiments can also be implemented without these detailed features. Furthermore, for the sake of comprehensibility, exemplary embodiments are described using block diagrams as a substitute for a detailed illustration. Furthermore, details and/or features of individual exemplary embodiments can be combined with one another without further ado, as long as it is not explicitly described to the contrary.

Embodiments described herein relate to microelectromechanical (MEMS) devices. Such MEMS devices can be multi-layered layered structures. Such MEMS can be obtained, for example, by processing semiconductor material at wafer level, which can also include a combination of multiple wafers and/or the deposition of layers at wafer level. Some of the exemplary embodiments described herein address the MEMS levels. A MEMS plane is understood to mean a plane which is not necessarily two-dimensional and/or non-curved and which essentially extends parallel to a processed wafer, for example parallel to a main side of the wafer or of the subsequent MEMS.

Embodiments described herein relate to layer stacks having multiple layers. Layers described in this context may, but not necessarily, be a single layer, but in embodiments may easily have two, three or more layers and are understood as a layered composite. Thus, both layers, from the material of which a movable element is formed, can be formed in multiple layers, as well as layers between which a movable element is arranged, which can be configured as at least part of a wafer and can have multiple layers of material, for example for Implementation of physical, chemical and/or electrical functions.

A plane direction can be understood as a direction within this plane, which can also be denoted by the English term "in-plane". Alternatively or additionally, a direction along which the layers in the layer stack alternate or are arranged one on top of the other can be referred to as the layer sequence direction. In this respect, the plane direction, in-plane, can refer to a direction perpendicular thereto.

Some of the exemplary embodiments described herein are described in connection with a loudspeaker configuration or a loudspeaker function of a corresponding MEMS component. It goes without saying that these statements, with the exception of the alternative or additional function of a sensory evaluation of the MEMS component or the movement or position of movable elements thereof, can be transferred to a microphone configuration or microphone function of the MEMS component, see above that such microphones constitute, without limitation, further exemplary embodiments of the present invention. Furthermore, other areas of use of MEMS are also within the scope of the exemplary embodiments described herein, such as micropumps, ultrasonic transducers or other MEMS-based applications related to moving fluid. For example, example embodiments may relate to a movement of actuators that may interact with a fluid, among other things.

Example embodiments relate to application of electrostatic forces for deflection of a movable element. However, the exemplary embodiments described can easily also be implemented using other drive principles, such as electromagnetic force generation or sensing. The deflectable elements can be, for example, electrostatic, piezoelectric and/or thermomechanical electrodes, which provide a deformation based on an applied potential.

1 shows a schematic side sectional view of a MEMS device 10 according to an embodiment. The MEMS device includes a layer stack 12, the may have a plurality of layers 12 ₁ , 12 ₂ , with additional layers 12 ₃ and possibly further layers also being able to be part of the layer stack 12 as an option. Some of the layer sequences can be mechanically connected to one another, but distances between adjacent layers can also be provided in certain areas. Some of the layers of the layer stack 12 can also be removed locally, as is shown for the MEMS layer 12 ₁ , for example. Here, the layer 12 ₁ , which is arranged with the layers 12 ₂ and 12 ₃ along a layer sequence direction 14 , can be removed locally in order to expose a movable element 16 so that the movable element 16 is movable at least with respect to the layer 12 ₂ . In this case, at least one component of the movement is perpendicular to the layer sequence direction 14 along a plane direction 18, ie in-plane. As explained in the context of exemplary embodiments, this can include a translatory movement along the direction of the plane 18 and/or a rotational component, for example a torsional movement.

The movable element 16 is arranged between the layers 12 ₂ and 12 ₃ , with a driving device 22 being provided to generate a driving force F along the plane direction 18 on the movable element 16, the driving force F being designed to to deflect the movable element 16. In some configurations, the force F can be generated almost perpendicularly to the layer sequence direction, with other directions also being possible, for example for torsional movements.

The drive device includes a drive structure 22a, which is mechanically firmly connected to the movable element. Furthermore, the drive device 22 includes a drive structure 22b, which is mechanically firmly connected to the MEMS layer 12 ₂ . In connection with the exemplary embodiments described herein, mechanically firmly connected is understood to mean arranging a further element mechanically firmly on another element, for example by means of a fixation, for example by gluing, bonding, coating, soldering or the like. Alternatively or additionally, for example, a conductive layer can be arranged on another layer in order to arrange at least part of the drive structure mechanically firmly on one layer. Alternatively or additionally, mechanically firmly connected is also understood to mean that, for example, an electrically conductive structure is an integral part of another structure. In a preferred configuration, for example, a semiconductor material can be made electrically conductive by doping it, in order to provide the function of an electrode, for example. This electrode is also considered to be mechanically fixed to the respective element understood to be connected, even if it is the same element from a different point of view.

According to one embodiment, for example, the movable element 16 is designed to be electrically conductive, for example by comprising electrically conductive materials, for example a metal material and/or a doped semiconductor material. Alternatively or additionally, the drive structure 22a can be applied to a base body of the movable element 16 in the form of an electrode structure, for example. In an analogous manner, for example, the drive structure 22b can comprise electrically conductive materials, for example with regard to an at least regional doping of semiconductor material of the layer 12 ₂ and/or by arranging an electrode structure.

The design of the MEMS component 10 such that a movement of the movable element 16 takes place in-plane and the drive structure is arranged along the layer sequence direction 14 makes it possible to have a comparatively large dimension 24 of the movable element 16 along the To obtain layer sequence direction 14, which is for example at least 75 microns, at least 100 microns, at least 500 microns or higher. A comparatively large area can be uncovered along the plane direction 18, which corresponds to the aspect ratios of known uncovering methods, for example the Bosch method. Because the drive device 22 can have a gap 26 between the drive devices 22a and 22b, which is independent of such an exposure method. This means that the drive structures 22a and 22b can be spaced apart by the gap 26 and arranged opposite one another, for example during a rest position of the movable element 16. A dimension of the gap 26 along the layer sequence direction 14 can be set by a bonding process.

For example, a dimension of the gap 26 can be at least partially determined by the joining of the layer stacks along the layer sequence direction 14, which, compared to an etching process, for example, can enable a comparatively small dimension of the gap 26, for example 10 μm or less, 5 μm or less or 1 µm or less. A corresponding aspect ratio of the dimension 24 compared to the gap 26 can be correspondingly high, which is advantageous for the MEMS device 10 since a large volume of fluid can be interacted with.

The movable element 16 can be formed in one layer or in multiple layers.

For example, the movable element 16 can have a plurality of at least two have at least three, at least four, at least five or more layers that are joined together, for example, by means of a bonding process. For example, different silicon layers can be connected to one another as part of a bonding of silicon wafers in order to obtain a high overall layer thickness or a large dimension 24, which means, for example, a low dependency or even independence on the aspect ratio of the etching process , such as the Bosch method can be produced.

FIG. 2a shows a schematic side sectional view of a section of a MEMS component 20 according to an embodiment. The drive structure 22b of the drive device is a structured electrode structure, for example, and comprises at least one electrode element 22b ₁ and one electrode element 22b ₂ , which are electrically insulated from one another, so that a first electrical potential is applied to electrode element 22b ₁ and a first electrical potential to electrode element 22b ₂ different second electrical potential can be applied. This includes, for example, alternating exposure of the electrode elements 22b ₁ and 22b ₂ to potentials of the same or different amplitudes, but can also mean simultaneous exposure of the electrode elements 22b ₁ and 22b ₂ to the same or different potentials, depending on which control of the MEMS device 20 is desired or required.

For electrical insulation, gaps 28 ₁ to 28 ₄ can be provided between the electrode segments, which can optionally also be filled with electrically insulating material or dielectric material.

The MEMS component 20 can comprise a plurality or multiplicity of movable elements 16 ₁ and 16 2 and possibly further movable elements, which are arranged next to one another along the plane direction 18 . The drive structure 22a described in connection with FIG. 1 can be part of one, several or all movable elements 16 ₁ and 16 ₂ .

The movable element 16 ₁ can be arranged symmetrically opposite the electrode gap 28 ₂ , for example to obtain a symmetrical drive. Alternatively, it is also possible to arrange the movable element asymmetrically opposite the electrode gap 28 ₂ , for example to enable asymmetrical control. Similarly, the movable element 16 ₂ can be arranged symmetrically or asymmetrically opposite the electrode gap 28 ₁ . For example, different potentials U ₃ and U ₄ can be applied to the movable elements 16 ₁ and 16 ₂ , whereby according to exemplary embodiments the movable elements 16 ₁ and 16 ₂ or their drive structures are electrically or galvanically connected to one another, so that the potentials U ₃ and U ₄ are the same or identical. Based on the potentials U ₁ , U ₂ , U ₃ and U ₄ , electrostatic forces can be generated which can lead to a deflection of one or more movable elements 16 ₁ and/or 16 ₂ along the direction of movement of the plane direction 18 . As a result, the driving force can be generated in interaction between the electrical potential of the movement structure and the potential U ₁ and/or U ₂ .

The drive structure 22b can have an electrode structure, which is preferably formed in a structured manner, for example in the form of interdigital electrodes. This means that further electrode elements that can be connected to the potential U ₂ can also be part of the drive structure 22b. According to further exemplary embodiments, however, individual electrode segments can also be electrically insulated from one another, so that, for example, the electrode elements which are jointly provided with the reference symbol 22b ₁ can also form electrode elements that can be individually subjected to potentials.

As shown in FIG. 2a, further drive structures 22c, 22d and/or 22e can be arranged on the sides of the layers 12 ₂ and 12 ₃ facing and/or facing away from the movable elements 16 ₁ and 16 ₂ . The additional drive structures 22c, 22d and 22e are optional. The drive structures 22d and 22e can be provided for arranging additional movable elements 16, in particular in the case of a stacked arrangement of the MEMS component. In a manner similar to that in which moveable members 16 ₁ and 16 ₂ are shown adjacent to drive structures 22b and 22c, additional moveable members may be located adjacent to drive structures 22d and/or 22e.

For example, the drive structure 22c on the MEMS layer 12 ₃ or the wafer 44 can be used to provide an additional drive force component between the movable element 16 ₁ and/or 16 ₂ and the drive structure 22c in addition to the drive force component using the drive structure 22b. This means that, compared to the description of the MEMS component 10, a first interaction between the movable element 16 ₁ and the drive structure of the wafer 42 and a second interaction between the movable element 16 and the drive structure of the wafer 44 are provided. For example, such a check can be carried out via a control device which is designed to apply appropriate voltages or potentials or control signals to the electrodes or conductive structures. The drive device can be designed to generate a first drive force component F ₁ based on the first interaction and a second drive force component F ₂ based on the second interaction. The MEMS component can be designed to generate the first force component and the second force component in the same direction or in phase, which can enable a to-and-fro movement of the movable element 16 ₁ parallel to the plane direction 18 , for example. A phase offset between the force components F ₁ and F ₂ can lead to a tilting or rotation about a suspension center M, for example a torsion of the movable element 16 ₁ . A back and forth rotation of the movable element 16 ₁ , for example about the center point or the center axis M, can also take place when the force components F ₁ and F ₂ are designed in antiphase. This means that it is possible for the upper and the lower drive structure to provide force components that are shifted relative to one another based on an individual control.

The drive device can have a further drive structure which can be arranged on a side of the MEMS layer 12 ₂ and/or 12 ₃ facing away from the movable element 16 ₁ or 16 ₂ , with a further movable element being arranged there adjacent to this drive structure to form a stacked arrangement with the movable member 16 ₁ and 16 ₂ .

The electrode structures can be connected to the layers 12 ₂ or 12 ₃ via connecting layers 32 ₁ to 32 ₄ , which can be particularly advantageous if the layers 12 ₂ and/or 12 ₃ are formed from semiconductor material. The layers 32 ₁ to 32 ₄ can be formed in an electrically insulating manner, for example, and can include silicon oxide and/or silicon nitride, for example. Other material choices are also possible without restriction.

The moveable elements 16 ₁ and 16 ₂ can optionally be arranged symmetrically across the gaps 28 ₁ to 28 ₄ , which can enable a symmetrical control of the moveable elements 16 ₁ and 16 ₂ , for example for a linear movement. Irrespective of this, for example in a rest position, positions deviating from this can also be provided in order to implement, for example, an asymmetrical control. The movable elements 16 ₁ and 16 ₂ can be moved toward or away from each other during an activation cycle, but can alternatively also be moved in phase, so that, for example, a distance between the movable elements 16 ₁ and 16 ₂ is changed the same or only insignificantly. In the other case, in which the movable elements 16 ₁ and 16 ₂ move alternately towards and away from one another, the volume of a partial cavity 36 between the movable elements 16 ₁ and 16 ₂ can be alternately reduced and enlarged, for example. For a fluidic exchange with an environment, openings 38 ₁ to 38 ₃ can be provided in any number and/or position in a first wafer 42 and/or second wafer 44, which can provide a bottom wafer and/or cover wafer, for example which the movable element 16 ₁ and/or 16 ₂ is arranged, so that fluid can flow into or out of the sub-cavity 36 .

FIG. 2b shows a schematic side sectional view of a portion of the illustration from FIG. 2a, in which, for example, the optional drive structures 22d and 22e are not shown.

In a comparable manner, FIGS. 2c and 2d show the corresponding section of the MEMS component 20, a movement 48 of the movable elements 16 ₁ and 16 ₂ towards one another taking place in FIG. 2c, starting from an exemplary idle state in FIG. 2b , so that the volume of the sub-cavity 36 ₁ between the movable elements 16 ₁ and 16 ₂ is reduced, while correspondingly the volumes of sub-cavities 36 ₂ and 36 ₃ adjacent to the movable elements 16 ₁ and 16 ₂ on from the sub-cavity 36 ₁ Facing away sides are enlarged, so that correspondingly arranged openings 38 ₁ and 38 ₂ fluid 46 can flow into the partial cavities 36 ₂ and 36 ₃ , while the openings 38 ₃ fluid 46 can flow out of the partial cavity 36 ₁ .

2d shows a complementary state in which the movement 48 is carried out in such a way that the movable elements 16 ₁ and 16 ₂ move away from one another, which can lead to the volume of the partial cavity 36 ₁ increasing again. while the volumes of the partial cavities 36 ₂ and 36 ₃ are reduced, so that the fluid 46 can flow in the opposite direction, for example through the opening 38 ₃ into the partial cavity 36 ₁ and through the openings 38 ₁ and 38 ₂ out of the partial cavities 36 ₂ and .36 ₃ out. 2b shows examples of force vectors F1a1, F1b1, F1b2, F1a2, F2a1, F2b1, F2b2 and F2a2, which indicate that a movable element 16 ₁ formed to be electrically conductive, for example, and/or a movable element formed to be electrically conductive, for example Movable element 16 ₂ based on potentials of the electrode elements of the drive structures 22b and 22c forces can be generated which can trigger the movement 48 from FIG. 2c or the movement 48 from FIG. 2d.

As can be seen from FIGS. 2a to 2d, a large number of movable elements 16 can be arranged along plane direction 18 in order to alternately reduce and enlarge adjacent partial cavities during activation in order to move a large amount of fluid, what is particularly advantageous for pump applications or loudspeaker applications.

In other words, the electrically conductive layers 22b and 22c can be subdivided in a first direction into at least two discrete partial regions 22b ₁ and 22b ₂ and 22 _C1 and 22 _C2 . These portions are electrically isolated from each other and separated by a gap 28 or an insulating medium such as silicon oxide therein and may constitute electrodes. The arrangement and interconnection of the electrodes is designed to be interdigital, for example. The distance between the partial areas is 1 μm, for example, but can also be 10 nm or even up to 10 μm. A first group of partial regions 22 _C1 and 22 _C2 is mechanically connected to the cover wafer via an insulating connecting layer 32 ₂ , for example. Another second group in partial areas 22b ₁ and 22b ₂ is mechanically connected to the bottom wafer via an insulating connecting layer 32 ₁ . In one group of sub-areas, for example 22b ₁ and/or 22 _C1 , a first sub-area is connected to a first signal voltage, and a second sub-area 22b ₂ and/or 22 _C2 is connected to a second signal voltage. For example, the signal voltages can have the same magnitude, but can also be phase-shifted by 180°, for example. The phase shift can also assume other values. Electrically identical partial areas of the respective groups can be arranged opposite each other on the cover wafer and base wafer.

The description of the arrangement and geometric configuration of the resistance elements 16 ₁ to 16 _n , where n can be an integer multiple of a, ie an integer, follows. The resistance elements, ie the movable elements, can, for example, be bar-shaped elements which have their direction of longitudinal extension in a second direction, which is arranged at right angles to the above-mentioned first direction. approximately along a centroid fiber. Such a dimension is indicated in Fig. 4a and Fig. 4b, for example, with the parameter I. Preferred lengths are, for example, between 10 μm and 10 mm, particularly preferred lengths are between 1 mm and 6 mm and particularly preferred lengths l are around 3 mm. The extension of the resistance elements in the first direction, ie parallel to the direction of movement, is very much smaller than the extension in the second direction. It should be noted here that a particularly preferred exemplary embodiment of a resistance element has a variable width, for example along the first direction. The width of the resistive element is smallest in the region of its centroid fiber and can be located in the region of the neutral axis of the resistive element, see point M. Towards its upper and lower borders, the width can increase again at the edge of the movable element. The width in the area of the centroid fiber is, for example, a value between 3 μm and 4 μm. The illustrated width in the area of the upper and lower boundary is, for example, a value between 7 μm and 8 μm. The width of the bar can also be made the other way around, ie thinner in the middle and thicker on the edge or thicker in the middle and thinner on the edge.

The extension, which can be referred to as height, for example, and runs in a third direction, which is arranged perpendicularly to the plane that is spanned between the first and the second direction, for example along the distance 34, is between 400 μm and 400 μm, for example 5000 μm, preferably between 650 μm and 1500 μm and particularly preferably around 1000 μm. The width of the resistance elements can vary in shape, as is also shown in FIGS. 3a to 3d.

The resistance elements are arranged in such a way that they cover two adjacent partial areas (22 _C1 and 22 _C2 , and 22b ₁ and 22b ₂ ) in the cover and base wafer area in equal parts. This covering also includes the insulating area between two partial areas 38. The insulating area 28 between two partial areas can be made of oxide (eg SiO ₂ , Si ₃ N ₄ or Al ₂ O ₃ ) or air and can be between 0.1 μm and be 10 μm wide.

The resistance elements 16 ₁ , 16 ₂ are at a distance 26 ₁ , 26 ₂ from the electrodes of the electrically conductive layers. This is, for example, between 0.01 μm and 10 μm, preferably between 0.05 μm and 1 μm and a particularly preferred distance of 0.1 μm. This distance forms the two-part capacitive actuator between beams, so- such as top and bottom wafers. The actuator that is supposed to move the resistance structures/bars therefore has no direct mechanical contact with the resistance structure. This distinguishes this solution from the other solutions where the actuator and the resistance structures have to be mechanically connected in order to get an acoustic effect from the resistance structures.

The balanced actor (actuator with linear deflection behavior) according to FIGS. 2a-d show different moments in time when the resistance elements are actuated:

The forces acting on a resistance element are shown below:

The force pulling to the left (first direction of movement): F _a1 = F _1a1 + F _2a1 = ~(U _DC +U _ACa ) ² /d

U _ACa = the signal voltage/AC voltage applied to electrodes 2a and 5a.

The force pulling to the right (second direction of movement): F _b1 = F _1b1 + F _2b1 - ~(U _DC +U _ACb ) ² /d;

U _ACb = the signal voltage/AC voltage applied to the electrodes 22 _C1 /22 _C2 and 22 _b1 /22 _b2 .

UDC is the DC voltage that is applied between the top/bottom wafer and the device wafer. d = distance between cover/bottom wafer and device wafer, 26 ₁ , 26 ₂ .

The resultant force on a resistance element is:

F ₁ - F _a1 - F _b1 - ~(2*U _DC *U _ACa - 2 _UDC * _UACb +U _ACa ² - U _ACb ² )/d

If the signal voltage/AC voltage U _ACa = - U _ACb = U _AC , then applies

F ₁ - ~ 4*U _DC *U _AC /d. the resulting force is linearly dependent on the signal voltage U _AC . The linearity between signal voltage and power is very important for the sound quality of a loudspeaker (distortion factor). a) For a balance of forces, the following applies: 22 _C1 and 22c ₂ or 22b ₁ and 22b ₂ have the same voltage U _ACa = U _ACb , the forces are all equal F _a1 = F _b1 and F _a2 = F _b2 : The resistance elements are equally located at 22CI/22C ₂ and 22b ₁ /22b ₂ ; b) The following applies to the movement of the resistance elements under 22c ₂ /22b ₂ : Voltage U _ACa <U _ACb . The forces have the following relationship to one another: F _a1 < F _b1 or F _a2 < F _b2 c) The following applies to the movement of the resistance elements under 22cV22b ₁ : U _ACa > U _ACb . The forces have the following relationship to one another: F _a1 > F _b1 or F _a2 > Fb ₂ ;

FIG. 3 a shows a schematic side sectional view of a MEMS device 30 according to an embodiment, which is modified with respect to several optional changes compared to the MEMS device 20 . While the principle effect of moving movable elements 16 ₁ and 16 ₂ towards or away from each other can be the same, for example to increase or decrease volumes of partial cavities 36 ₁ , 36 ₂ and 36 ₃ in order to allow fluid to pass through openings 38 ₁ , 38 ₂ 1 and 38 ₃ , a movable element 16' ₁ or 16' ₂ of the MEMS device 30 has a changed configuration.

Unlike the MEMS component 20, where the movable elements 16 are formed integrally electrically conductive, for example, the movable elements 16' ₁ and 16' ₂ can be formed from a semi-conductive or non-conductive material, so that the drive structure 22a and/or or 22f by means of layers 32 ₁ and/or 32 ₂ and comprising electrode elements 22a ₁ , 22a ₂ , 22f ₁ and 22f ₂ is mechanically firmly connected to the movable element or a base body thereof. This means that, unlike in the MEMS component 20, where electrode structures are arranged on the substrate layers 12 ₂ and 12 ₃ , electrode structures can also be provided on the movable elements 16' ₁ and 16' ₂ as an alternative or in addition. The drive structures 22a and 22f can be actuated or connected in the same or identical manner and, for example, brought to an identical potential, for example for the electrode elements 22a ₁ and 22f ₁ and 22a ₂ and 22f ₂ , with individual connection also being able to be provided as an alternative. This means an electrode The structure can be arranged on a side of the MEMS layer 12 ₁ or of the movable element which faces the MEMS layer 12 ₂ and/or the MEMS layer 12 ₃ and form at least part of the drive structure.

In contrast, in the case of the MEMS component 30, the layers 12 ₂ and/or 12 ₃ can optionally be formed to be electrically conductive, so that a separate arrangement of electrode structures can be dispensed with. Alternatively, the layers 12 ₂ and 12 ₃ can also be provided with electrode structures, as is described in connection with the MEMS component 20 .

Regardless of this, but also in combination, the layers 12 ₂ and 12 ₃ can have surface topographies 52 ₁ to 52 ₂ which can be provided, for example, for symmetrical control in the area of opposite electrode columns 28 and in the form of elevations or depressions opposite main sides 12 ₂ A or 12 ₃ B can be implemented, that is, locally the distance between the movable element and the layer 12 ₂ or 12 ₃ in the region of the topographies 52 can be increased by implementing the topography as a depression in the material is reduced or reduced by implementing the topography as an elevation. In some configurations, this surface topography may be desired or required. If, for example, the electrodes are arranged on the movable element, it is advantageous to structure the base and/or cover wafers in the same or similar manner as shown in order to achieve a movement. The topographies 52 can be used to set electrostatic forces. In other words, surface topographies 52 can be elevations or holes. Such structuring can be arranged symmetrically on both sides of the wafer 42 and/or 44 . This means that the movable element 16' ₁ and/or 16' ₂ on a side facing the second MEMS layer 12 ₂ and/or the second MEMS layer 12 ₂ on a side facing the movable element 16' ₁ or 16' ₂ Facing side may have a surface structure or surface topography in order to change a distance between the movable element 16 ' ₁ or 16' ₂ and the second layer 12 ₂ locally.

While the surface topographies 52 ₁ , 52 ₂ , 52 ₅ and 52 ₆ can be used for setting the electrostatic forces between the drive structures for the control shown, the surface topographies 52 ₃ , 52 ₄ , 52 ₇ and 52 ₈ can be used as dummy structures be, for example, to avoid bending of the wafer 42 and / or 44 as much as possible. Referring to the structured electrically conductive layers or electrodes 22c/22e and 22b/22d in FIG. 2a, it should be noted here that that using an equivalent structuring of the electrodes 22e in sub-areas related to the sub-areas of the electrically conductive layer 22c and/or using an equivalent structuring of the electrodes 22d in sub-areas related to the sub-areas of the electrically conductive layer 22b a similar or the same Effect in terms of avoiding a bending can be obtained, regardless of whether adjacent to the electrically conductive layers 22d and / or 22d further movable elements not shown in Fig. 2a are arranged.

Optionally, in an embodiment with a stacked arrangement of movable elements, for example adjacent to the drive structure 22d and/or 22e in FIG Setting options are obtained.

FIG. 3b shows a schematic side sectional view of a movable element 16″ according to an exemplary embodiment, which can be used, for example, to be used in the MEMS component 16 as a movable element 16′ ₁ or 16′ ₂ . A base body 54 of the movable element 16″ can be formed, for example, from semiconductor material, such as silicon, and can have an approximately rectangular geometry, for example, it also being possible for thickenings to be provided at the ends of the base body 54 .

In contrast to a plane arrangement of the electrode structures according to FIG. 3a, the electrodes 22a ₁ , 22a ₂ , 22f ₁ and/or 22f ₂ can also be arranged in part on side surfaces of the movable element 16″ or the base body 54, which makes it possible, for example to also generate electric fields along these sides, which can be advantageous in the event of dynamic movement of the movable element 16''.

The shape of the base body 54 is independent of the implementation of the electrodes on the side surfaces. Such an implementation is also readily possible on the movable elements 16 ₁ and 16 ₂ .

In other words, FIGS. 3a and 3b show a so-called balance actuator. FIGS. 3a and 3b show an alternative exemplary embodiment of an elementary cell with linear deflection behavior. The difference from the exemplary embodiment in FIGS. 2a-d is the location of the electrically conductive layers on the resistance elements. This alternative location makes the resistive element an active resistive element. The resistance element is characterized in that the electrically conductive layers are each connected to the resistance element via an electrically insulating layer. The shape of the resistance elements with the conductive layers in width can be different.

Furthermore, an alternative deflectable and active resistance element is also shown (FIG. 3b). In this case, the electrically conductive layers are arranged around part of the circumference of the resistance element. In other words, electrically conductive layers are arranged not only between the resistance element and the cover wafer and between the resistance element and the base wafer, but also on the sides of the resistance elements that enclose the cavities.

Fig. 3c shows a schematic side sectional view of the base body 54 from Fig. 3b,

FIG. 3d shows a schematic sectional side view of a base body 54' that is different from FIG. 3c and has a multiple convex configuration, in contrast to the single concave configuration of FIG. 2a.

The cross section of the movable element can be polygonal, for example rectangular, single-curved or multiply-curved, wherein a curvature can be convex or concave, with multiple curvature also permitting mixed forms thereof. Alternatively or additionally, the movable element can have variable dimensions perpendicular to the layer sequence direction in the cross section along the layer sequence direction 14, i.e. for example along the plane direction 18.

FIG. 4a shows a schematic side sectional view of the movable element 16' ₁ of the MEMS component 30 according to a first embodiment of the electrode structures. For example, the electrode segments 22f ₂ and 22a ₂ can be arranged opposite one another on the base body 54 regardless of its cross section and, for example, provide a planar contact along a length l. The electrode element 22a ₂ can have a height h ₅ and the electrode element 22f ₂ can have a height h ₂ along the layer sequence direction 14, which can lead to an overall height h _tot of the movable element 16′ ₁ .

Fig. 4b shows a schematic side sectional view of an alternative embodiment, in which both the electrode element 22f ₂ and the electrode element 22a ₂ in segments 56 ₁ to 56 ₁₀ or 56 ₁₁ to 56 ₂₀ , the number of 10 segments 56 being merely exemplary and any number of at least two, at least three, at least five, at least eight, at least ten or more can be.

As is shown by way of example for the connection 58, the segments 56 of an electrode 56f ₂ or 22a ₂ are electrically or galvanically coupled to one another, so that when an electrical potential is applied within the group 56 ₁ to 56 ₁₀ and 56 ₁₁ to 56 ₂₀ have the same potential.

In this case, a segment can have a dimension I _s which, for example, has a value in a range between 0.5 μm and 2 μm, with other values also being able to be implemented on the basis of individual designs the length l can be provided as a constant or also variable distance labst, which separates two segments 56 from one another, but is bridged by means of an electrically conductive connection 58 .

This means that the movable element can be designed over an element length l along an axial direction of extension perpendicular to the layer sequence direction such that the electrode 22a ₂ and/or 22f ₂ has a plurality of electrode segments 56 . Adjacent electrode segments 56 can be electrically connected to one another by electrical conductors 58, the electrical conductors having a lower mechanical rigidity in the direction perpendicular to the element length, ie for example along the plane direction 18, than the electrode segments. As a result, movement or deformation of the movable elements can be prevented to a small extent by the mechanical rigidity of the electrode material.

In other words, the electrically conductive layers can be segmented in the first direction, as shown in the side view in FIG. 4b. In this case, the segments are spaced apart from one another. Advantageously, the rigidity of the deflectable elements can already be addressed in the design. In this case, the resulting gaps are preferably not filled. 4b thus shows a view of an embodiment with segmented electrode layers.

The extension of the resistance elements in the third direction is indicated, inter alia, in Fig. 4a with h and the extension of the electrically conductive layer 22a or 22f is with h ₂ or h ₅ denotes. The ratio of h to h ₂ or h to h ₅ is 20%, preferably 5% or more preferably 1%, ie h ₂ and h ₅ are thinner than the body 54.

The expansion of the resistance elements in the first direction is shown, inter alia, in FIG. 4b. An alternative arrangement of the conductive layers 22a and 22f is shown here, which, as already mentioned above, reduces the rigidity of the deflectable element. The length of the resistance element in the first direction is denoted by l. The length of a segment is denoted by I _s . The distance between the segments is denoted by labst.

5a shows a schematic top view of a part of a MEMS component 50 ₁ according to an embodiment, in particular the configuration of the movable elements 16' ₁ to 16' ₅ , which are exemplary in accordance with the movable elements 16' ₁ and 16' ₂ of the MEMS device 30 may be formed. Partial cavities 36 ₁ to 36 ₆ are arranged between adjacent movable elements or between a movable element and surrounding substrate 62 in the case of movable elements 16′ ₁ and 16′ ₅ . The movable elements 16′ ₁ to 16′ ₅ can be viewed as beams that are firmly clamped on both sides, with the interdigital interconnection of the electrode elements 22a ₁ and 22a ₂ being shown as an example. It is clear that the respective electrode elements of adjacent movable elements 16′ ₁ to 16′ ₅ can have the same potentials due to the end-to-end interconnection, but that severing such a configuration can also lead to an individual interconnection.

A direct voltage (DC) can be applied to the electrode elements 22a ₁ and 22a ₂ so that, for example, the direct voltage DC is applied alternately to the electrodes 22a ₁ and 22a ₂ . Alternatively, an AC voltage can also be applied, which is indicated by AC- and AC+. Such a configuration can also take place simultaneously, which can lead, for example, to attractive forces between adjacent movable elements in order to move them towards one another.

In other words, FIG. 5a shows a schematic representation of a contacting of the electrodes when they are connected to the beam, the movable elements. Equally, such a configuration can also be implemented for electrodes that face the cover wafer and/or the base wafer. As can be seen from FIG. 5a, the movable elements 16' ₁ to 16' ₅ can be designed directly to interact with the fluid, for example by the base bodies moving the fluid or being moved by it. Alternatively, additional elements such as plate elements or the like could also be arranged on the movable elements, which are moved by the movable elements and in turn interact with the fluid.

FIG. 5b shows a schematic top view of a MEMS component 50 ₂ according to an exemplary embodiment in a view comparable to FIG. 5a. In contrast to the MEMS component 50 ₁ , however, the movable elements are in the form of movable elements 16'', as illustrated in FIG. 3b, for example. This means that the electrodes 22a ₁ and 22a ₂ also run on side walls of the movable elements in addition to a top or bottom side, it being noted here that terms such as top, bottom, left, right, front, rear and the like are used here do not have a restrictive effect, but only serve to illustrate the point, since it is clear that the terms are mutually interchangeable due to a changing orientation of the bodies in space.

However, it can be seen that when the movable elements 16" ₁ to 16" ₅ move or deform along the direction of movement 18, an advantage can be obtained if the electrodes are structured, as described in connection with FIG. 4b or Fig. 5b is explained. The electrical connection 58 between two adjacent segments 56 ₁ and 56 ₂ can be made, for example, by locally thinning out or removing the corresponding electrode, which can lead to low mechanical resistances of the electrode elements when the movable element 16'' ₁ is curved .

The partial cavities 36 ₁ to 36 ₆ can be parts of an overall cavity, with the partial cavities 36 ₁ to 36 ₆ being able to be alternately enlarged and reduced due to the movement of the movable elements 16" ₁ to 16" ₅ .

The movable elements of the MEMS components 50 ₁ and 50 ₂ can be fluidly coupled to one another, so that when only one of the movable elements is actuated, an adjacent movable element can also be moved in the non-actuated state. That is, the motion of the fluid may couple to an adjacent movable element, whether actuated or unactuated. Optional Adjacent movable elements can also be coupled to one another by means of a coupling element, not shown, for example in a central area, for example 1/2 or the like. Such a coupling element makes it possible to carry out a smooth movement of the coupled movable elements.

As further shown in MEMS devices 50 ₁ and 50 ₂ , different potentials may be applied to electrodes 22a ₁ and 22a ₂ . The interdigital structure can be formed in such a way that mutually facing electrodes of adjacent movable elements are connected to a combination of the potentials AC− and AC+, which means that the mutually facing electrodes both have different potentials or, to put it another way, different Potentials of the different electrodes 22a ₁ and 22a ₂ face each other. This also applies to the DC wiring, which takes place alternately at the electrodes 22a ₁ and 22a ₂ , for example, so that a wired electrode faces an unwired electrode.

In other words, FIGS. 5a and 5b show top views of the exemplary embodiments from FIGS. 4a and 4b, respectively, with FIG. 5b also showing contacting of the electrodes when they are connected to the beam. 5a and 5b are top views of the layers from Fig. 4a/Fig. 4b of a MEMS-based sound transducer with linear deflection behavior in a simplified representation with a limited number of actively deflectable elements. The illustration shows a possible electrical interconnection of the actively deflectable resistance elements, as shown in FIGS. 4a/4b. In this case, the two subregions interlock like a comb (in other words, interdigitally) and are arranged over the entire length of the respective passive resistance element. Equally, such a configuration can also be implemented for electrodes that face the cover wafer and/or the base wafer.

FIG. 6 shows a schematic side sectional view of a part of a MEMS device 60 according to an embodiment. In addition to the cavity 66, which is subdivided into partial cavities by means of four movable elements 16' ₁ to 16' ₄ , outer regions are also shown there, in which the interconnection of the electrodes is illustrated in more detail. Electrodes and/or other areas can be uncovered through recesses 64 ₁ to 64 ₇ so that they are available for contacting. As shown by the recesses 64 ₁ to 64 ₅ , this can be done so that all electrodes along one side of the MEMS device 60 are accessible. 7a shows a schematic side sectional view of a MEMS device 70 according to an embodiment. The MEMS component 70 includes, for example, a configuration as is described in connection with the MEMS component 20 . Each two adjacent movable elements 16 ₁ and 16 ₂ , 16 ₃ and 16 ₄ or 16 ₅ and 16 ₆ can form a unit cell 68 ₁ , 68 ₂ or 68 ₃ of the MEMS component 70 . While openings 38 ₁ , 38 ₂ and 38 ₃ of the wafer 44 can be assigned exclusively to the unit cells 68 ₁ , 68 ₂ and 68 ₃ , for example, openings 38 ₄ and 38 ₅ of the wafer 42 can be assigned to neighboring unit cells 68 ₁ and 68 ₂ or 68 ₂ and 68 ₃ are shared.

Recesses 64 ₁ , 64 ₂ , 64 ₃ and 64 ₄ for contacting the electrodes 22 _C1 , 22 _C2 , 22b ₁ and 22b 2 can be provided in the substrate layers 12 ₂ and 12 ₃ . Alternatively or additionally, cutouts 64 ₅ and/or 64 ₆ can be provided for local exposure of layer 12 ₁ in order to connect it to a potential, for example a reference potential (ground GND).

In other words, FIG. 7a shows a cross-sectional illustration of an exemplary embodiment of a MEMS-based sound transducer with linear deflection behavior with 3 elementary cells arranged next to one another. The structure with passively deflectable resistance elements is shown. Thus, the electrically conductive layers are each connected to the base and cover wafer via an electrically insulating layer. The elementary cells are connected to one another via cavities of adjacent passive, deflectable resistance elements. In addition, the positions of possible lower and upper outlet openings in the base and cover wafer are shown. Areas 64 are provided for electrical contacting of the partial layers. Likewise, areas for electrical contacting of the partial areas of further electrodes are provided. The contacting areas are shown as openings, which are led down to the respective electrically conductive layers in an etching process, for example as bores or square recesses or rectangular grooves. The exemplary embodiment is not limited to the location of the electrically conductive layers shown. In order to build up a potential difference between the layers 22b and 22c and the passively deflectable elements, contacting with GND in the layer 12 ₁ is possible. A structure with actively deflectable elements according to FIGS. 3a to 4b is also possible.

The contacting of the chip in Fig. 7a is z. B. take place by wire bonding. Because the contact holes are placed on both sides of the chip, the wire bonding process must also take place from 2 sides. FIG. 7b shows a schematic side sectional view of the MEMS component 70 in a configuration in which electrically conductive elements 72 ₁ to 72 ₆ are arranged in the cutouts 64 ₁ from FIG. 7a in order to enable contacting of the corresponding areas.

The electrically conductive areas or elements 72 ₁ to 72 ₆ may be spaced from the surrounding material by gaps 74 ₁ to 74 ₄ , which gaps may optionally be filled with electrically insulating material. Electrically conductive structures 76, for example made of the material of the electrically conductive elements 72 or another electrically conductive material, can be arranged through electrically insulating connecting layers 32, which differ from the material of the connecting layers 32 or the electrically insulating property thereof Area surrounding electrodes can be enclosed to avoid short circuits. The element 72 ₅ can provide a contact between the layer 12 ₁ and a partial area of the layer 12 ₃ , as the element 72 ₆ is also shown. In this case, the element 72 ₅ can also be electrically insulated from other elements, for example partial regions of the electrically conductive layer 22c. Contact can be made on both sides at this point.

In other words, FIG. 7b shows a sound transducer with linear deflection behavior and an alternative structure of a MEMS-based sound transducer, which differs with regard to the contacting and 101 the electrically conductive layers. In this case, the contacts to the layers are not made by gaps. Alternatively, the layers are connected to the top and bottom wafers by vias through conductive elements. The layer 12 ₁ is connected to the bottom or top wafer by the conductive plugs. The electrical potentials in the cover or base wafer are separated by the trench (or recesses). The advantage of this design is that the layers are not contacted in the recesses, but on the surface of the base or cover wafer.

7c shows a schematic sectional side view of a MEMS component 70' similar to this, in which the contacting by means of recesses 74 ₁ to 74 ₅ is only from one side, that of the wafer 44, for example a cover wafer. Accepting the comparatively deep trenches, the MEMS component 70 can be placed simply on a substrate, since the electrical interconnection from one side can be sufficient. In other words, when the conductive layers are placed on the resistance elements, the electrodes can be contacted in a variety of ways. The electrodes can be contacted from two sides or only from one side. In other words, FIG. 7c shows a sound transducer with linear deflection behavior: It is similar to FIG. 3a, except that the contact is made from one side of the chip. i.e. all electrodes necessary for the actuation are accessible (through the recesses) from one side of the chip. In this case, wire bonding of the finished chip is easier to implement because the chip can only be wire bonded from one side.

Analogously to the contacting options shown in FIG. 7a, the drive variant in FIG. 3a can also be contacted.

8a shows a schematic side sectional view of a MEMS component 80 according to an exemplary embodiment, in which the partial cavities 36 ₁ to 36 ₇ locally extend into at least one of the layers 12 ₂ and 12 ₃ in that cutouts 78 are provided there, for example between adjacent openings 38 ₁ and 38 ₂ , 38 ₂ and 38 ₃ and/or in the area of the openings 38 ₄ , 38 ₅ , 38 ₆ and/or 38 ₇ .

For example, the layer 12 ₁ can be connected to an alternating potential U _AC or -U _AC or +U _AC so that this potential can also be present at the movable elements 16 ₁ to 16 ₆ . In contrast, the layers 12 ₂ and 12 ₃ can be connected to a reference potential GND.

8b shows a schematic side sectional view of the MEMS component 80 from FIG 8a is described, in which the surrounding substrate of the layer 12 ₁ is however connected to the reference potential, which can enable simple and safe handling of the MEMS component. Optionally, instead of designing the substrate for connecting to the reference potential, electrical insulation can also be provided on the MEMS component 80 . Fig. 8b shows the MEMS component 80 in a state in which the movable elements 16 ₁ to 16 ₆ have moved in pairs within the unit cells 68 ₁ , 68 ₂ and 68 ₃ toward each other, so that corresponding main sides 16 ₁ A and 16 ₂ A or 16 ₃ A and 16 ₄ A, which delimit partial cavities 36 ₂ and 36 ₄ , are moved towards one another. _FIG . _8c _shows a _schematic side _sectional view of the _MEMS component 80 from _FIG . 68 ₂ , 68 ₃ are moved away from each other to create a reverse fluid flow.

In other words, FIGS. 8a to 8c show sound transducers with non-linear deflection behavior: FIGS. 8a-c show a structure of a MEMS-based sound transducer in three deflection states. Likewise, a simplified two-electrode configuration is shown. The layers of the cover wafer 12 ₃ and base wafer 12 ₄ form a first electrode and the layer of the device wafer or the passively deflectable resistance elements form a second electrode. The resistive elements are simplified in this illustration and may have other cross-sections, such as those described herein. The resistance elements are arranged in a cavity, which is worked out of the layer 12 ₁ by etching processes and through further layers, which are the cover and base wafers. At least one end, preferably two opposite ends, are connected to the substrate of layer 12 ₁ . The layers preferably have cover and base wafer structures, which result in a large volume of the cavity. The layers are connected to layer 12 ₁ via an insulating layer 32 ₁ /32 ₂ .

The resistive elements have major faces. Main sides are characterized in that they are arranged opposite one another in adjacent resistance elements and delimit partial cavities 36 ₂ , 36 ₄ and 36 ₆ which are connected to the upper outlet opening 38 ₁ - 38 ₃ . Correspondingly, the opposite sides of the resistance elements are characterized by including the cavities 36 ₁ , 36 ₃ , 36 ₅ and 36 ₇ which are simultaneously connected to the lower outlet openings 38 ₄ -38 ₇ . In addition, the opposite sides of the resistance elements are characterized in that they delimit the partial cavities 36 ₁ , 36 ₃ , 36 ₅ and 36 ₇ which connect the elementary cells to one another.

FIG. 8a shows the resistance elements in a non-deflected state.

Figure 8b shows the resistance elements in a deflected state in a first time interval with an additional applied voltage (combination between DC and AC) between 0 and 100 V, preferably between 1 and 50 V, particularly preferably between 1 and 25 V, about 24 V. Here, the resistance elements steer along the direction of movement 18 out. Adjacent resistance elements of an elementary cell move towards one another, so that the distance between the respective main sides decreases and, as a result, the volume of the partial cavities 36 ₂ , 36 ₄ , 36 ₆ also decreases. Due to the reduction in the volume of the partial cavities, fluid is transported out of the partial cavities through the outlet openings 38 ₁ -38 ₃ . In the same time interval, the opposite sides of the resistance elements move in one direction, so that the distances between the opposite sides are increased. Equally, the enclosed volume of the cavities 36 ₁ , 36 ₃ , 36 ₅ , 36 ₇ is also increased as a result. The volume flow thus generated transports fluid through the openings 38 ₄ -38 ₇ into the partial cavities.

FIG. 8c shows the resistance elements in a deflected state in a second time interval that directly follows the first time interval. The first and second time intervals alternate in this order over a long period of time, so that pressure pulses, for example as sound waves, are emitted.

In the second time interval, the resistance elements are supplied with a different voltage (DC+AC), the phase of which is shifted by, for example, 180° compared to the voltage in the first time interval, with other phase angles also being adjustable. The phase shift can also assume other values greater than zero. The resistance elements thus move along the direction of movement 18 in a direction which is opposite to the direction in the first time interval. In other words, the distance between the opposite sides of adjacent resistance elements decreases, as a result of which the volume of the partial cavities 36 ₂ , 36 ₄ , 36 ₆ is increased and as a result of which a volume flow of fluid is transported through the openings 38 ₁ -38 ₃ into the partial cavities. The distance between the opposite sides of adjacent resistance elements decreases in the same way, so that a volume flow of fluid conveys out of the partial cavities 36 ₁ , 36 ₃ , 36 ₅ and 36 ₇ through the openings 38 ₄ -38 ₇ .

FIG. 9 shows a schematic perspective view of parts of a MEMS component 90 according to an embodiment, for example in the form of the wafer 42 and the layer 12 ₁ . By way of example, 10 movable elements 16 ₁ to 16e are shown, which can be surrounded by partial cavities 36 ₁ to 36 ₁₁ . Reference number 15 shows a step, chamfer or rounding which sets back an inner area of the movable elements 16 compared to a peripheral area of the remaining layer 12 ₁ or reduces it in height, so that during subsequent bonding processes, for example for arranging the wafer 44 , A mechanical contact to the movable elements 16 is omitted. In other words, FIG. 9 shows a MEMS-based sound transducer in a perspective view. Shown are the layers containing the passive resistance elements and the layer (bottom wafer) connected to layers 22b ₁ /22b ₂ . The layer that includes the cover wafer is not shown. The configuration of the layers 22b ₁ and 22b ₂ is likewise shown, which interlock like fingers and are thus arranged next to one another in the area of the deflectable passive elements. The layers 22b ₁ /22b ₂ are electrically separated by the region 28, which represents electrical insulation. The layers 12 ₂ and 12 ₁ have different thicknesses. For example, the layer 12 ₂ has a thickness of 400 μm. The thickness of the layer 12 ₁ can have values between 400 μm and 5 mm, for example. The contacts in the layer 12 ₁ are disclosed by 72i, which connect the control to the electrically conductive layers 22b ₁ /22b ₂ with further contacts in the layer (not shown). The control signals are then distributed into the zones of the respective areas of the layers 22b ₁ and 22b ₂ by means of suitable contacts 72 .

Another aspect of this embodiment is the placement of the openings 38. In this embodiment, these openings connect the cavities 36 (in other words, trenches or recesses) to the surrounding fluid. These openings are shown as rectangular in this embodiment. In this exemplary embodiment, the respective cavities 36 are connected to two openings which are each at a discrete distance from one another. Equally, however, it is also possible for an opening to have a length over the entire length of the passive resistance element or a length deviating therefrom. Likewise, the exemplary embodiments are not limited to a rectangular shape either. Other shapes that deviate from a rectangular shape are part of exemplary embodiments that should only be mentioned here.

The reference 15 refers to a circumferential step or chamfer or rounding which is arranged between the layer 12 ₁ and the substrate of the resistance elements. With a height difference of approximately 100 nm, the substrate of the resistance elements is slightly embedded in relation to the substrate 12 ₁ in order to prevent the resistance elements from being strained during the necessary bonding process of the cover layer. Equally, the step can also be provided in the area of the bonding zone of the layer 12 ₂ . 10 shows a schematic perspective view of a MEMS device 100 according to an embodiment. Compared to other exemplary embodiments described here, the movable elements 16 ₁ to 19 ₉ are elements that are only clamped on one side, for example adjacent movable elements that are clamped on opposite sides and can be arranged in the sense of interdigital elements. This means that exemplary embodiments described herein are not limited to movable elements clamped on both sides.

In other words, FIG. 10 shows a further exemplary embodiment of a MEMS-based sound transducer 100, which has deflectable resistance elements 16 ₁ to 16 ₉ connected on one side to the surrounding substrate of layer 12 ₁ , it also being possible for any number of resistance elements to be designed here .

Fig. 11 shows a schematic perspective view of a MEMS component 110 according to an embodiment or a part thereof, namely the layer 12 ₂ , which can have both openings 38 and interdigital electrodes 22b ₁ and 22b ₂ , the contacts 72 ₁ to 72 ₁₂ , which can pierce the electrodes 22b ₁ and 22b ₂ , for example, as explained in connection with FIG. 7b by way of example.

Furthermore, spacers 84a and/or 84b can be provided, which can limit a distance, in particular a minimum distance, between the movable element sweeping over the layer 12 ₂ and the movable element itself. The spacers can be formed from electrically insulating material, for example, and can prevent a cover wafer and/or a base wafer from being bonded to the fin over a large area during wafer-level bonding, since their dimensions are relatively small, in the range of a few micrometers. The spacers can be used as a transport lock. For example, the spacers 84a and/or 84b can be e.g. B. in a certain hydrofluoric acid combination, such as HF-GPE (GPE = Gas-Phase Etching, gas-phase etching) removed before the chip is put into operation. Spacers are optional and can also be provided only on part of the movable elements.

In other words, FIG. 11 shows the layer 12 ₂ of a MEMS-based sound transducer in a perspective view and substantiates the implementation of the description of FIG. 12a shows a schematic plan view of parts of a MEMS device 120 ₁ according to an embodiment. By way of example, the electrode 22b ₂ has a rectangular shape and is arranged approximately centrally across an intermediate space between two adjacent movable elements 16 ₁ and 16 ₂ , as is also shown, for example, in FIG. 2a. The movable elements 16 ₁ and 16 ₂ can be formed, for example, in the shape of a comb.

12b shows a schematic plan view of parts of a MEMS component 120 ₂ , in which the movable elements 16 ₁ and 16 ₂ can be formed as hollow bodies, for example, which allows material savings. Irrespective of this, the electrode 22b ₂ can have a concave design, for example.

12c shows a schematic plan view of parts of a MEMS component 12O3, in which the movable elements 16 ₁ and 16 ₂ are formed as solid bodies and, independently of this, the electrode 22b ₂ is formed as convex in shape. The different details of FIGS. 12a, 12b and 12c can easily be combined with one another. This means that the electrodes of the drive structures arranged on the substrate can have a constant or variable lateral dimension along an axial course perpendicular to the layer sequence direction, ie parallel to the plane direction 18 . The same also applies to the electrodes on the movable elements or in the movable elements.

In other words, FIGS. 12a-12c show different exemplary embodiments of the deflectable resistance elements in a plan view of an area of an alternative elementary cell. 12a shows a comb-shaped configuration. 12b shows a concave configuration of the deflectable resistance element and the layer 22b ₂ shown as an example. Furthermore, it is shown that the resistance elements can also be thin-walled bodies that have no material in the area of the centroid fiber. FIG. 12c, on the other hand, shows a convex shape of the represented components of the unit cell. These refinements are used advantageously when, for example, a specific force is required during the deflection and the rigidity of the resistance elements has to be optimized (eg minimized). Or there are increased requirements for a transition between the resistance element and the surrounding substrate that is as stress-free as possible, so that it makes sense to widen the resistance element in the area of the transition. Equally, the shape of the deflection of a resistance element can be influenced the. It is understandable for a person skilled in the art that a hollow resistance element has a greater light-weight character than a filled resistance element. Thus, the performance of a sound transducer can be directly influenced by the geometric design of the resistance elements. It is undeniable that different configurations can also be combined in a MEMS converter.

13 shows a schematic side sectional view of parts of a MEMS device 130 according to an embodiment. There, for example, the layer 12 ₂ and/or the layer 12 ₃ is electrically conductive and divided into different segments or areas by means of electrically insulating elements or areas or segmentations 92, which are subjected to different potentials 86a/86b or 88a/88b can, while the layer 12 ₁ with, for example, H-shaped movable elements 16 ₁ and 16 ₂ can be subjected to a reference potential. For example, the potential 86a can be AC- and the potential 86b AC+ and/or a DC voltage potential can be applied alternately to different segments. The same applies to the potentials 88a/88b.

In other words, FIG. 13 shows a resistance element with a linear deflection behavior. FIG. 13 shows a further exemplary embodiment according to FIGS. 8a-c. The H-shaped design of the resistance elements and the double potential management in the cover and base wafer are different:

Resistance element with linear deflection behavior: This means that when a voltage is applied to 12 ₁ ; 86, 88 electrical forces arise. When the stresses 86a/86b or 88a/88b are equal, the forces balance and the resistance element does not move. However, if the voltage between 86a/86b or 88a/88b becomes different, then an imbalance arises and the resistance element moves linearly in one direction. If the voltage between 86a/86b or 88a/88b is reversed, then the resistance element moves linearly in the opposite direction. This advantageously results in a very large volume of the surrounding cavity, with which a high sound pressure level of the resulting sound transducer is possible. However, this also requires a large force with a large deflection of the resistance elements. Which is why this structure enables a linear relationship between the deflection force to be applied and the applied voltage. FIG. 14 shows a schematic side sectional view of a MEMS device 140 according to an embodiment that may be consistent with the MEMS device 130. FIG. However, unlike MEMS device 130, MEMS device 140 may include block-shaped or solid moveable elements 16 ₁ and 16 ₂ .

In other words, FIG. 14 shows a resistance element with a linear deflection behavior, FIG. 14 concretising FIG. 13 with solid resistance elements.

15a shows a schematic side sectional view of a MEMS 150 according to an embodiment in which the insulating layers 32 ₁ and 32 ₂ as well as exemplary electrode layers 22 ₁ and 22 ₂ are formed circumferentially around the layers 12 ₂ and 12 ₃ as well as one electrically insulating layer 32 ₃ around layer 12 ₁ . In this way, simple wafer bonding can be made possible.

In other words, FIG. 15a shows an exemplary embodiment of a MEMS-based sound transducer in a cross-sectional representation. This exemplary embodiment shows the MEMS sound transducer in a method step of its manufacture. It can be seen here that spacers 84 are connected to the resistance elements on both sides in the vertical direction. These spacers represent force dissipation points that make it possible to achieve uniform bonding of the layers 12 ₁ . In a further step in the manufacturing process, these spacers are then removed. It is equally conceivable that these spacers are at the same time a means of securing during transport, which enables damage-free transport during the manufacturing process. It is conceivable that these spacers are only destroyed when a signal is applied to them for the first time and thus represent a transport safeguard throughout the entire B2B process. Because there are many such spacers on the chip, it is possible to design them of different sizes, so that when removing the spacers, only some are specifically removed, while others remain: the smaller spacers are removed and the larger ones remain. This would make it possible to specifically free (release) only certain resistance elements or make them flexible. In this way, one could use or release the same chip for different applications (with more or less free resistive elements).

15b shows a schematic side sectional view of an intermediate product 150' for a MEMS device according to embodiments described herein. Material 94 is shown remaining in a center region when etching from a first side 96 ₁ and a second side 96 ₂ to obtain indentations 98 ₁ to 98 ₈ . As soon as the etching has progressed to such an extent that the opposing indentations meet and the material 94 has been detached, movable elements can be detached as a result. For example, the intermediate product 150' can also be an already bonded wafer example and/or a wafer with a high thickness, in which a doubled aspect ratio can be produced due to the etching on both sides.

15b shows an exemplary embodiment of a converter in a sectional view. This illustration is not intended to claim any method of fabricating a MEMS. Rather, it shows the advantage of such a construction as claimed by the device. An important aspect of this invention is that the resistance elements must be symmetrical in order to ensure uniform deformation during the movement process. An asymmetrical structure leads to the non-uniform deformation behavior just described. As a result, there would no longer be a linear relationship between the applied voltage and the deflection of the resistance element, resulting in a high distortion factor. An asymmetrical structure results from the method used in the etching process. By working out material to form recesses, trenches/trench or cavities, there are no parallel boundaries, but always funnel-like recesses. The width of the recess is always smaller at the base (bottom) than at the top.

The direction of etching and the subsequent bonding of wafers thus largely determines the formation of the resistance elements.

Likewise, it is illustrated by FIG. 15b that a stacking of resistive elements is possible in order to increase the resulting aspect ratio of the transducer element without the limitations affecting the Bosch method being used.

It shows that the device wafer was etched from 2 sides (front and back) in order to increase the aspect ratio of the resistor elements. show:

98 ₁ -98 ₄ layer with an etching direction from the front side; 98 ₅ -98 ₈ layer with an etching direction from the back,

• layer 94 is shown only schematically to show that the etches will eventually meet; 94 is no longer present in the final product.

The advantages for etching from 2 sides: the fins are symmetrical relative to the plane that is spanned by the first and second direction. The areas 96F ₁ and 96F ₂ shown are therefore of the same size and the electrical forces to be applied, which deflect the resistance elements in the direction of movement, are of the same size. A uniform deflection by the same amount is thus guaranteed.

If both layers are etched from only one side, the surfaces 96F ₁ and 96F ₂ are not formed uniformly or even differ from one another in terms of their surface area. The result would be an uneven deflection of the resistance elements.

- Doubling of the aspect ratio of the recesses (in other words, trenches) to 60. Due to the stacking of the resistance elements, the resulting converter elements are no longer limited to the Bosch method.

15c shows a schematic side sectional view of a part of a MEMS device 150'' according to an embodiment. The movable elements 16 ₁ and 16 ₂ can be obtained, for example, by stacking structures similar to the intermediate product 150′, in that several of these intermediate products are stacked on top of one another, for example by means of wafer bonding. It should be noted that only two of the three movable elements obtainable in FIG. 15b are shown in FIG. 15c. By increasing the aspect ratio accordingly by joining along the plane direction 14, an increase in the efficiency that can be obtained, for example, by means of a loudspeaker configuration of the MEMS component can be obtained, for example since the sound pressure level (Sound Pressure Level - SPL) is correspondingly increased. In addition, stacking along the layer sequence direction M enables high rigidity along this direction, which leads to a lower susceptibility to so-called pull-in Effects can lead and thus a lower holding force or a lower vertical deflection can lead parallel to the layer sequence direction 14, which is advantageous. A structure is thus shown in which the movable element has a plurality of layers connected by means of a bonding process.

In order to increase the SPL, it is possible, as shown in FIG. 15c, to connect several layers to one another. Theoretically, the aspect ratio of the trenches or resistance elements can be greatly increased. In this case, the “continuity” of the device level is advantageous in comparison to the required support layers (e.g. handle wafers in BSOI wafers) reported in the prior art.

A configuration is illustrated with reference to FIGS. 16a, 16b and 16c, in which the electrodes on the movable element are provided with n-doping in the electrodes 22a ₁ and 22f ₁ or with p-doping in the electrodes 22a ₂ and 22f ₂ can be obtained. A reference position can be obtained when the layer 12 ₂ and/or 12 ₃ is connected, possibly with a local reduction of the distance, to a reference potential, for example 0V, GND. With a negative voltage in the layers 12 ₂ and 12 ₃ , a force can be exerted on the movable element 16, which pushes the electrodes 22a ₂ and 22f ₂ into the closely spaced region, due to the accumulation of movable positive holes in the regions 22f ₂ and 22a ₂ leads to an external negative voltage (AC-). In Fig. 16c a complementary configuration is shown, in which due to a positive voltage on the layers 12 ₂ and 12 ₃ the high number of movable negative electrodes, which are accumulated in the areas 22 ₁ and 22a ₁ , in the direction of the surface topography 52 to move.

An accumulation of a mobile negative electron can also correspond to a depletion of an immobile positive ion and vice versa. A space charge zone can arise due to a depletion in addition to an accumulation.

Electrically insulating layers 102 ₁ and 102 ₂ , for example comprising silicon nitride or silicon oxide, can be arranged in order to neutralize the surface states and to obtain a state of the movable element 16 which is as neutral as possible.

16a-c each show an alternative drive with linear deflection behavior and based on a cover drive. This configuration can advantageously improve the usual linear structure, which provides three electrodes. It is important in all three Figures disclose that connected to the deflectable element is a layer that includes N- and P-doped regions that are adjacently arranged and individually connected to the deflectable element. The layers are cover and base wafers, which provide a protuberance 52 in the area of the deflectable elements. These protuberances are materially connected to the cover and base wafer and are at a minimal distance from the deflectable element, so that an acoustic short circuit between the partial cavities that adjoin the deflectable element is prevented. Figure 16a shows the device in an undeflected state with no voltage applied.

16b shows the alternative drive in a first deflection state. The deflection of the deflectable element is based on the field effect. The figure shows the deflection in a first direction. The deflection is based on a negative voltage AC- being applied to the top and bottom wafers. Due to the field effect, the charge carriers accumulate in the P region (movable holes/+ directly at the interface to the oxide, 10-20 nm deep). This is accompanied by a depleted zone (immobile ions/-, 1-2 μm deep) in the N range. The largest change in capacitance, which is equivalent to the deflection force, occurs when the fin overlaps the lid in the P region.

16c shows the alternative drive in a second deflection state. The deflection of the deflectable element is based on the field effect. The figure shows the deflection in a second direction. The deflection is based on a positive voltage AC+ being applied to the top and bottom wafers. Due to the field effect, the charge carriers accumulate in the N region of the layers (mobile holes/+ directly at the interface to the oxide, 10-20 nm deep). This is accompanied by a depleted zone (immobile ions/-, 1-2 μm deep) in the P region of the layers. The largest change in capacitance, which is equivalent to the deflection force, occurs when the fin overlaps the lid in the P region.

A complementary state is indicated with reference to FIGS. 17a, 17b and 17c, in which the n-doped regions 22 _C1 and 22 b ₁ arranged on the layers 12 ₂ and 12 ₃ or integrated there, in addition to p-doped regions 22 c ₂ and 22b ₂ are arranged. These can be covered by electrically insulating layers 102 ₁ and/or 102 ₂ . In this case, the movable element 16 can be formed to be electrically conductive, for example also via a corresponding doping. Based on the application of a negative voltage AC- or a positive voltage AC+, a movement of the movable element 16 towards the n-doped regions 22 _C1 and 22b ₁ or towards the p-doped regions 22b ₂ and 22 _C2 can be triggered.

In other words, FIGS. 17a-c show an alternative drive to FIGS. 16a-c, based on the field effect, in which the doped layers are integrated in the cover wafer and the base wafer.

18a shows a schematic plan view of a MEMS device 180 according to an embodiment. In contrast to other exemplary embodiments described herein, the movable element is mechanically connected to the MEMS layer 12 ₃ , which is not shown in FIG. 18a, via an elastic region. The elastic area can include a layer arranged for this purpose, a remaining layer or a material provided especially for this purpose. The movable member is configured to rotate or deform the elastic portion based on the driving force.

The elastic area can be provided in an area 104, for example,

Fig. 18b shows a schematic side sectional view in the AA' plane of Fig. 18a. Due to the mechanical and elastic connection in the region 104, the movable element 16 ₂ as well as the other movable elements connected to the layer 12 ₃ can perform the movement adjacent to the layer 12 ₂ similar to a rocking movement or rocking movement, so that adjacent to the layer 12 ₂ there can be a high movement amplitude and in the region of the layer 12 ₃ a small movement amplitude, but with high material stretching.

The advantage of such a configuration is that only two instead of three active disks/wafers are required and no additional layers need to be provided for this, for example in the area of the cover 12 ₃ .

As explained in connection with other embodiments, a driving device can be implemented in a variety of ways, such as by providing electrodes on layer 12 ₂ and/or the movable element 16 ₂ and/or by For example, doped areas are arranged. Electrodes on a side facing the layer 12 ₂ , an end face, of the movable element 16 ₂ can be referred to as an end drive. Such a drive from the front side thus forms an embodiment of the present invention. In other words, the fin, the movable element 16 ₂ , can be driven starting from the end face of the fin by designing the device wafer accordingly. For example, the first drive structure can be arranged at least on the end face of an end face of the movable element. For example, electrodes can be arranged on or in the layer 12 ₁ . Positioning can be done, for example, face-to-face between the movable element 16 ₂ and the side of the layer 12 ₁ associated with the faces of the movable elements. A height of the electrodes can correspond to the height of the movable element or be less.

In other words, FIGS. 18a and 18b show an alternative structure of a sound transducer in a plan view and a side view. This differs significantly by the connection of the deflectable element to the cover wafer in a region 104. This connection is particularly preferably implemented as a material bond. The alternative direction of movement, perpendicular to the lateral extension of the resistance element, is shown at 18 . The greatest deflection occurs in the area of the bottom wafer. The smallest deflection occurs in area 104, the connection area of the resistance element to the cover wafer. The connection area 104 can have a rigidity that deviates from the rigidity of the cover wafer and the resistance element and is preferably lower. In this case, the connection area 104 is a spring element. The resulting sub-cavities, which are separated from one another by the resistance elements, are connected to the surrounding fluid through openings in the base wafer and cover wafer (not shown).

A method based on exemplary embodiments described herein is described using a schematic flowchart in FIG. A step 1910 of the method 1900 can include driving two drive structures arranged along a layer sequence direction along which a multiplicity of MEMS layers of the MEMS component are arranged. A step 1920 includes generating a driving force on a movable element of the MEMS device perpendicular to the layer sequence direction by driving to deflect the MEMS device.

The method can be carried out in such a way that two adjacent electrode elements are controlled in the sense of a so-called “balanced” or linear control of the drive device, which are electrically insulated from one another by an electrode gap, a symmetrical and/or linear deflection of the movable element is controlled by the electrode elements being controlled symmetrically over time with respect to the applied potentials around a reference potential, such as GND. Alternatively, the method can also be carried out asymmetrically or unbalanced or non-linearly, in that the deflection of the movable element is controlled asymmetrically in the time average along an actuation direction with respect to an opposite direction. This can be obtained by different potential levels and/or different time intervals.

The exemplary embodiments described herein relate to microelectromechanical systems, MEMS, which are designed to have a large effective area for interaction with a fluid. Here, an increase in the effective area of deflectable displacement elements is in the foreground in some designs. The displacement elements, the movable elements 16, can be in contact with a surrounding fluid and interact with it directly or indirectly. For example, in the case of micro loudspeakers equipped with such a MEMS, a high sound pressure level can be generated in relation to the surface area of the MEMS. Equally, however, use as micropumps, ultrasonic transducers or other MEMS-based applications is also possible within the scope of the exemplary embodiments described herein, since these are connected to one another by the task of moving fluid.

Core aspects of the present invention are summarized again below in other words. Exemplary embodiments solve the problem of structuring limitations in existing etching processes, i. That is, a limitation of the geometric resolution, such as the thinnest trenches to be etched, in volume-processing processes such as electroerosion, lithography, galvanic molding, nano-stamping, milling or other SI structuring, for the representation of field-driven drive effects, such as electrostatic - table or electromagnetic in the plane.

The "Bosch" Si structuring method limits the aspect ratio (depth to width) of etched Si structures to typically 30. With the current variants for micro loudspeakers (NED, muscle, comb), the structuring of electrostatically deflectable elements (driving force) as well as the structuring of passive elements (resistance structures, displacement elements, fluidic resistance structures), which describe the fill factor of the chip area, is limited by the Bosch method. Driving force and fill factor are the Key parameters to achieve higher Sound Pressure Level (SPL) per chip area (SPL/mm ² ) in microspeakers. Therefore, new, simpler drive variants must be found that are not limited by the aspect ratio of the Bosch method and allow, for example, 100 dB/mm ² or higher.

The solution of the invention is represented by the device and the method for deflecting one or more resistance elements in Chapter 6 of this description of the invention. The solution includes a device that contains a MEMS sound transducer as a layered system. The core of the invention is:

Increase in drive power: The drive power of the new drive is no longer limited by the aspect ratio of the Bosch method. The basic idea is to create the electrode gap by bonding at least two discs. In this way, the active electrode gap can be set particularly small, regardless of the limitations of the Bosch process, and a large force can thus be generated. This gap is created between the one pane to be bonded and the other. The actively movable element (e.g. a beam structure) in the first wafer to be bonded (device wafer) is then spaced apart across the gap from the other wafer to be bonded (top or bottom wafer). The drive is thus generated via the gap along the circumference or parts of the circumference of the actively movable element.

In one embodiment ("cover drive"), the force is defined by the vertical distance from the top of the cover or base wafer to the top of the device wafer. The distance between the lid and device wafer can be defined independently of the Bosch method and thus larger aspect ratios or larger drive forces can be achieved with the lid drive. The drive takes place here along the longitudinal edges on the upper side and/or lower side of the actively movable element (as the upper lower part of the circumference) as the closest electrode side to the cover and/or base

In one version (“end drive”), the force between the actively moving element (e.g. elongated flap element) and the cover or base is determined by the lateral distance between the two bonded panes. The two discs will at least partially mesh. Consequently, the drive takes place along front rarely (lateral part of the circumference of actively moving structures). Compared to the cover drive, additional conductive layers can be dispensed with here.

Several devices can also be stacked together, i.e. all disks have actively deflectable elements

Increasing the fill factor: The fill factor of a micro-loudspeaker, for example, is characterized by the maximum between the fill factor of the actuator and the fill factor of the resistance structures in the displacement level (device level). If the fill factors of the two components of the micro-speaker are limited, e.g. by the Bosch method, then it becomes difficult to arbitrarily increase the fill factor of the micro-speaker. It is therefore important to make the fill factor of the actuator and the resistance structures independent of the Bosch method. In the lid drive, the fill factor of the actuator as well as the resistance structure level is independent of the Bosch method.

Compared to the known prior art, the cover drive can be characterized, for example, in that an electrically conductive layer is arranged between a cover wafer and the layer containing fluidic resistance elements. Likewise, another electrically conductive layer is arranged between the same layer containing resistance elements and a bottom wafer.

In the context of this description, a resistance element does not mean an electrical resistance, but a resistance element that interacts with a surrounding fluid, such as the movable element 16. In other words, this resistance element can also be referred to as a displacement element, fin or active or passive actuator.

The first and the second electrical layer can be structured in such a way that one or more electrical voltages that are separate from one another can be applied within the two electrical layers. If only one voltage (per top/bottom wafer) is required (depending on the application), the top/bottom wafers themselves can be used as the first and second electrical layers.

If two or more voltages (per lid/bottom wafer) are necessary (depending on the application) the following applies: The first and second electrically conductive layers are mechanically strong and connected to the layers of the top or bottom wafers via an insulating connecting layer. The main sides of these electrically conductive layers face away from the respectively adjacent layers of the top and bottom wafer and face one another. A further layer is arranged between the two main sides of the electrically conductive layers, from which a cavity is formed by SI structuring methods. In relation to the plane of the layer, which is arranged parallel to the layer of cover and handling wafers, this cavity surrounds at least one resistance element. Comparable to the cavity itself, a resistance element is formed from a doped semiconductor material by SI structuring methods and subdivides the cavity into partial cavities.

Linear operation as well as non-linear operation can be implemented with the cover drive. The exemplary embodiments with linear deflection behavior and non-linear deflection behavior differ from one another. Preferred exemplary embodiments are drives with linear deflection behavior.

In other words: With the cover drive, both a “balanced actor” (linear actuator) and a “non-balanced actor” can be implemented.

The following is meant by the "balanced actor" linear operation/linear deflection method/linear deflection behavior: when an electrical voltage is applied to the first and second conductive layers, electrical forces arise between the conductive layers and the resistance elements. When the voltage is the same on all conductive layers, the electrical forces balance and the resistive element does not move.

However, if the voltage within the first and second conductive layers is not equal (voltage 1 and voltage 2), then an imbalance arises and the resistive element moves linearly in one direction or the other. When voltage 1 and voltage 2 change in phase opposition (one increases and the other decreases), then two electric forces 1 and 2 acting in opposite directions act on each resistive element and accordingly one force increases and the other decreases. The resulting force (F1 +F2) is linear depending on the applied voltages 1 and 2. This means that the movement of the resistance element also depends linearly on the voltage. The linearity between the applied electrical signal and the deflection of the resistive element affects the sound of a loudspeaker. The more linear the relationship, the lower the distortion factor. The more linear the connection, the better the sound can be reproduced by the loudspeakers.

The "unbalanced actor" non-linear operation / non-linear deflection method means the following:

- Only one force (not two) acts on the resistance elements in a specific direction. This force depends quadratically on the voltage, or the movement of the resistance element depends quadratically on the voltage. This means that there is no linear dependency between the voltage and the movement of the resistance element. Accordingly, the quality of the sound suffers. In other words, the distortion factor of the loudspeaker is significantly higher compared to a loudspeaker with a linearly operated sound transducer.

A "non-balanced actor" (non-linear operation/non-linear deflection method) is usually easier to implement technologically because only one voltage has to be applied to the conductive layers (not two or more). I.e. the conductive layers do not have to In one exemplary embodiment, the conductive layers could even be dispensed with completely, so that the necessary voltage can be applied directly to the cover or base wafer.In this case, the cover and base wafers can be structured , see Fig. 8a-c.

Advantageously, the dense packing that is made possible in the core idea of the invention can be combined with a microresonator structure, so that the sound radiation in the low-frequency range is improved.

In other words, the electrodes and all corresponding partial elements are formed in one or more layers. The partial electrodes are electrically insulated by a distance 28, which can include, for example, oxide or nitride, for example SiO ₂ , Si ₃ N ₄ or Al ₂ O ₃ . A method for controlling and deflecting the resistance elements and thus also the interaction with the surrounding fluid can be the same between the different movable elements, suspended on one wafer or exposed by both wafers.

The advantages of the cover drives described here are that

1 . the force of the actuator can be controlled through the gap between the movable element and the base wafer or cover wafer during the bonding between the wafers and is not determined by an etching method, for example. This eliminates the limitation, for example of the Bosch method to an aspect ratio of around 30. That is, the actuator can be made with an aspect ratio greater than 30.

2. Furthermore, the use of BSOI wafers can be dispensed with. Standardized Si wafers, which are significantly cheaper, can be used for the cover wafer or the base wafer as well as for the device wafer, the layer 12 ₁ .

3. In contrast to classic NED (Nanoscopic Electrostatic Drive) or comb drives, a BSOI wafer can also be used, which, however, conventionally cannot be processed from two sides in order to increase the aspect ratio. In the manufacture of a cover drive described herein, both BSOI wafers and wafers can be processed on both sides, so that the trenches between the resistor structures, which are produced using the Bosch method, can have a double aspect ratio, for example 2×30, i. i.e., about 60. If several device wafers are bonded together, the aspect ratio can be further increased, for example as described in connection with FIGS. 15b and 15c. For example, an aspect ratio of 120 (two device wafers), 180 (three device wafers), 240 (four device wafers), etc. can be obtained.

4. Since the fill factor of the actuator (see first advantage) and the device level (see previous advantage) can be independent of methods such as the Borsch method, the fill factor of the overall system, i.e. the number of actuators or resistive structures/unit area can be greatly improved. a) Because parts of the actuator, namely the electrode gap, are decoupled from the device level (core idea of the invention), the mechanical and moving elements can be packed more densely in the device level and thus the fill factor of the overall system (number of actuators or resistor structures / unit area) can advantageously be greatly improved (more sound per area). b) In addition, the system, which is symmetrical with regard to half the device height, can be stacked and thus the apparent aspect ratio can theoretically be increased without limit. The basis for this is the unnecessary presence of any supporting layers or similar relative to the device level.

5. Simple technology for device and also for cover/base wafers: filled HR trenches are not available in order to implement insulation on the chip (HR = high aspect ratio). No short circuits are to be expected within one level (between the resistance element and the top and bottom wafer). This significantly increases the yield of the chips that can be isolated from a wafer without short circuits.

6. The final component of an exemplary embodiment consists only of Si and SiO2. No AL2O3 layers or other layers are necessary, which e.g. can induce tension (stress) in the system.

7. The resistance structure is driven from both sides (from above and below). The actuator is present symmetrically from both sides (top and bottom) and along the entire length of the resistance structure. The resistive structures do not wobble compared to the case where the resistive structures are only driven from one side.

8. No electric field between the resistor structures: device wafer has the same potential everywhere -> no filter effect.

9. Direct bonding Si-SiO2 or SiO2-SiO2 is possible at 1000°C: 25-50 wafers can be bonded in one oven at the same time. This results in cost savings in production a. It is possible to avoid a lateral pull-in between the resistor structures: all resistor structures have the same potential.

Although some aspects have been described in the context of 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 also counts as a corresponding method step or as a feature of a method step understand is. Similarly, aspects that have been described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

Depending on the particular implementation requirements, embodiments of the invention can be implemented in hardware or in software. Implementation can be performed using a digital storage medium such as a floppy disk, DVD, Blu-ray Disc, CD, ROM, PROM, EPROM, EEPROM or FLASH memory, hard disk or other magnetic or optical memory, on which electronically readable control signals are stored, which can interact with a programmable computer system in such a way that the respective method is implemented. Therefore, the digital storage medium can be computer-readable. Some exemplary embodiments according to the invention thus include a data carrier which has electronically readable control signals which are capable of interacting with a programmable computer system in such a way that one of the methods described herein is carried out.

In general, exemplary embodiments of the present invention can be implemented as a computer program product with a program code, with the program code being effective to carry out one of the methods when the computer program product runs on a computer. The program code can also be stored on a machine-readable carrier, for example.

Other exemplary embodiments include the computer program for performing one of the methods described herein, the computer program being stored on a machine-readable carrier. In other words, an exemplary embodiment of the method according to the invention is therefore a computer program which has a program code for carrying out one of the methods described herein when the computer program runs on a computer. A further exemplary embodiment of the method according to the invention is therefore a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for carrying out one of the methods described herein is recorded.

A further exemplary embodiment of the method according to the invention is therefore a data stream or a sequence of signals which represents the computer program for carrying out one of the methods described herein. The data stream or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example via the Internet.

Another embodiment includes a processing device, such as a computer or programmable logic device, configured or adapted to perform any of the methods described herein.

Another embodiment includes a computer on which the computer program for performing one of the methods described herein is installed.

In some embodiments, a programmable logic device (eg, a field programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform any of the methods described herein. In general, in some embodiments, the methods are performed on the part of any hardware device. This can be hardware that can be used universally, such as a computer processor (CPU), or hardware that is specific to the method, such as an ASIC.

The embodiments described above 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 occur to others skilled in the art. will shine. 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 exemplary embodiments herein.

Claims

patent claims

1 . A MEMS component comprising: a layer stack (12) having a plurality of MEMS layers arranged along a layer sequence direction (14); a movable element (16) formed in a first MEMS layer (12 ₁ ); which is arranged between a second MEMS layer (12 ₂ ) and a third MEMS layer (12 ₃ ) of the layer stack (12), a drive device (22) with a first drive structure mechanically fixed to the movable element (16). (22a) and a second drive structure (22b) mechanically firmly connected to the second MEMS layer (12 ₂ ); wherein the drive device (22) is designed to generate a drive force (F) perpendicular to the layer sequence direction (14) on the movable element (16), and the drive force (F) is designed to deflect the movable element.

2. MEMS device according to claim 1, wherein the first drive structure (22a) and the second drive structure (22b) are spaced apart by a gap and arranged opposite to each other; wherein a dimension of the gap along the layer sequence direction (14) is set by a bonding process.

3. MEMS device according to claim 1 or 2, wherein the movable element comprises a plurality of layers connected by a bonding process.

4. MEMS component according to one of the preceding claims, in which the second drive structure (22b) is a structured electrode structure with at least a first electrode element and a second electrode element electrically insulated therefrom; wherein the MEMS component is designed to apply a first electrical potential to the first electrode element and a different second electrical potential to the second electrode element; wherein the MEMS component is further designed to apply a third electrical potential to the first drive structure (22a) in order to interact with the third electrical Potential to generate the driving force (F) with the first electrical potential or the second electrical potential.

5. MEMS device according to claim 4, wherein the first electrode element and the second electrode element are electrically isolated from each other by an electrode gap (28), wherein a rest position of the movable element (16) symmetrically and/or asymmetrically opposite the electrode gap (28) is arranged.

6. MEMS device according to one of the preceding claims, wherein the movable element is polygonal, single-curved or multi-curved in a cross section; or in which the movable element has a variable dimension perpendicular to the layer sequence direction (14) in a cross-section along the layer sequence direction (14).

7. MEMS component according to one of the preceding claims, in which the electrodes of the second drive structure (22b) along an axial course perpendicular to the layer sequence direction (14) have a constant or variable lateral dimension perpendicular to the axial direction.

8. MEMS component according to one of claims 1 to 6, wherein the drive means (22) has a third drive structure (22c) which is mechanically fixed to the third MEMS layer (12 ₃ ), wherein between the first A first gap is arranged between the drive structure (22a) and the second drive structure (22b), and a second gap is arranged between the first drive structure (22a) and the third drive structure (22c); wherein the drive device (22) is designed to generate the drive force (F) based on a first interaction between the first drive structure (22a) and the second drive structure (22b) and a second interaction between the first drive structure (22a) and to provide the third drive structure (22c).

9. MEMS component according to claim 8, in which the drive device (22) is designed to generate a first drive force component based on the first interaction and a second drive force component based on the second interaction, the MEMS component being designed to generate the first driving force component and the second driving force component in phase or with a phase offset.

10. MEMS component according to one of claims 1 to 7, wherein the movable element is mechanically connected to the third MEMS layer (12 ₃ ) via an elastic region (104); wherein the movable member is configured to rotate based on the driving force (F) while deforming the elastic portion (104).

11 . 11. The MEMS device of claim 10, wherein the first drive structure is frontally disposed on a front face of the movable element.

12. MEMS component according to one of the preceding claims, in which an electrode structure is arranged on one of the second MEMS layer (12 ₂ ) facing and/or on one of the third MEMS layer (12 ₃ ) facing side, and at least forms part of the first drive structure (22a).

13. MEMS component according to one of the preceding claims, in which the movable element on a side facing the second MEMS layer (12 ₂ ) and/or the second MEMS layer (12 ₂ ) on a side facing the movable element (16 ) side facing has a surface structure in order to change a distance between the movable element (16) and the second MEMS layer (12 ₂ ) locally.

14. MEMS component according to one of the preceding claims, in which the electrodes of the first drive structure (22a) and/or electrodes of the second drive structure (22b) are arranged and interconnected interdigitally.

15. MEMS component according to one of the preceding claims, comprising a multiplicity of movable elements which are arranged next to one another in a common MEMS plane and are coupled to one another fluidically or by means of a coupling element.

16. MEMS component according to claim 15, in which a drive structure with at least two connected electrodes arranged next to one another are arranged on each of the movable elements (16), of which an electrode with a first electrical potential and a second electrode with a second, connected to different electrical potentials; wherein facing electrodes of adjacent moveable elements are connected to a combination of the first electrical potential and the second electrical potential.

17. MEMS component according to one of the preceding claims, in which the movable element is movably arranged in a MEMS cavity, wherein at least one partial cavity of the cavity is alternately enlarged and reduced by means of a movement of the movable element (16), wherein the sub-cavity extends locally into the second MEMS layer (12 ₂ ).

18. MEMS component according to one of the preceding claims, in which the movable element has an element length along an axial stretching direction perpendicular to the layer sequence direction (14), wherein an electrode of the first drive structure (22a) along the element length Has a plurality of electrode segments, with adjacent electrode segments being electrically connected to one another by means of electrical conductors, with the electrical conductors having a lower mechanical rigidity than the electrode segments in a direction perpendicular to the element length.

19. MEMS device according to one of the preceding claims, wherein the moveable element is adapted to provide an interaction with a fluid.

20. MEMS component according to one of the preceding claims, wherein the drive device (22) has a fourth drive structure (22d) on one of the movable element (16) facing away from the second MEMS layer (12 ₂ ). - is ordered, with a further movable element being arranged adjacent to the fourth drive structure (22d), and with the movable element (16) forming a stacked arrangement.

21 . A method of operating a MEMS device, comprising the steps of: Driving (1910) two drive structures arranged one on top of the other along a layer sequence direction along which a multiplicity of MEMS layers of the MEMS component are arranged, and

generating (1920) a driving force on a moveable element of the MEMS device perpendicular to the stack direction by driving to deflect the MEMS device.

22. The method as claimed in claim 20, in which a symmetrical and/or linear deflection of the movable element (16) is controlled by means of a MEMS component of two adjacent electrode elements which are electrically insulated from one another by an electrode gap (28), by driving an electrode element about a reference potential that is symmetrical over time with respect to the applied potentials.

23. The method according to claim 20, wherein the deflection of the movable element

(16) is driven asymmetrically in time average along an actuation direction with respect to an opposite direction.