MEMS-Schallwandler

Abstract

The invention relates to a MEMS sound transducer (1), comprising: a membrane (2) which is located between at least two wall structures (3, 4), at least one first stopper structure (5) which is directly or indirectly connected to one of the wall structures (3) and limits the movement of the membrane (2) in a first direction (7), at least a second stopper structure (9) that is directly or indirectly connected to the membrane (2) and limits the movement of the membrane (2) in an opposite second direction (12), wherein the stopper structures (5, 9) are realized within the MEMS sound transducer (1) and are manufactured using micromechanical manufacturing processes.

Description

State of the art

[0001] Several MEMS sound transducers are known from the state of the art.

[0002] US10129651 B2 discloses a MEMS microphone comprising a backplate, a spring, and a diaphragm. In one embodiment, the diaphragm is supported approximately at its midpoint by a support. The support is connected approximately at the midpoint of the diaphragm and approximately at the midpoint of the backplate. The diaphragm is connected to a spring that provides an electrical connection. The diaphragm can be electrically biased via this connection. One or more overtravel stops are attached to the backplate and extend through an opening in the diaphragm. The overtravel stops are configured to prevent movement of the diaphragm in a radial direction opposite to the backplate. The diaphragm incorporates a tension gradient, corrugation, or other structure that establishes or determines the stiffness of the diaphragm.

[0003] CN218041775U discloses a MEMS audio transducer for generating sound waves, wherein the MEMS audio transducer comprises at least one transducer structure, in particular a piezoelectric transducer structure. The audio transducer arrangement includes an electronic unit for controlling the at least one transducer structure of the MEMS audio transducer. The electronic unit comprises an electronic control unit and a power source. The power source is electrically connected to the electronic control unit and supplies a DC input signal to the electronic control unit. The electronic control unit is configured to process an audio input signal into an audio output signal. The audio input signal comprises an AC input signal, and the audio output signal comprises an AC output signal and a DC output signal.The electronic control unit is designed so that the converter structure is controlled by the audio output signal. The electronic unit is designed so that the MEMS audio converter structure can be driven with a DC output signal of 3V or less. This reduces the stress on the converter structure and thus extends its lifespan.

[0004] The object of the present invention is therefore to produce an improved MEMS sound transducer that offers higher mechanical robustness and improved functionality with precise control of the diaphragm deflection. Disclosure of the invention

[0005] The invention relates to a MEMS (micro-electromechanical system) sound transducer, comprising: a membrane that is mounted between at least two wall structures, at least one first stopper structure that is directly or indirectly connected to one of the wall structures and limits the movement of the membrane in a first direction, at least one second stopper structure that is directly or indirectly connected to the membrane and limits the movement of the membrane in an opposite second direction, the stopper structures are implemented within the MEMS transducer and manufactured using micromechanical manufacturing processes.

[0006] A MEMS (microelectromechanical systems) device, such as the MEMS-based transducer according to the invention, can be a multilayered structure. The MEMS-based transducer can be obtained, for example, by processing semiconductor material at the wafer level, which may also involve a combination of several wafers and / or the deposition of layers on wafer planes. The embodiments described herein may refer to layer stacks with multiple layers. However, the layers described in this context may not necessarily be a single layer, but in exemplary embodiments may readily comprise two, three, or more layers and be understood as a layered composite. Thus, both layers from whose material a moving element is formed can be multilayered, as can layers between which a moving element is arranged, which, for example,can be designed as at least part of a wafer and can have multiple material layers, for example to implement physical, chemical and / or electrical functions.

[0007] The MEMS transducer can be manufactured using a micromechanical manufacturing process, such as a structuring process like etching or grinding, and / or a coating process, such as a deposition process.

[0008] Etching is a well-known structuring method in semiconductor technology and can be one of the following structuring methods: photolithography, plasma etching, chemical etching, or physical etching.

[0009] The deposition process may preferably include physical vapor deposition and / or chemical vapor deposition.

[0010] The stopper structures can be fabricated from a first substrate or wafer using a structuring process such as etching or grinding. Subsequently, the remaining elements of the MEMS transducer can be fabricated from a second substrate or wafer using the same structuring process. Finally, the stopper structures can be attached to the membrane, for example, by bonding.

[0011] Bonding is a process step in semiconductor and microsystems technology in which two semiconductor elements are joined together and can include one of the following methods: silicon direct bonding, anodic bonding, eutectic bonding, glass-frit bonding, adhesive bonding and / or low-temperature anodic bonding.

[0012] The MEMS transducer can be designed as a sensor and / or as an actuator, and in particular as an ultrasonic sensor, a loudspeaker and / or a microphone.

[0013] One advantage of the MEMS transducer is that integrating the stopper structures directly into the transducer increases its mechanical robustness and reliability. This integration, and thus the use of semiconductor technologies, enables precise manufacturing. This, in turn, significantly reduces the risk of damage and therefore considerably improves mechanical robustness and reliability.

[0014] Another advantage is that the precise micromechanical manufacturing allows for exact limitation of the membrane movement in both directions, which significantly reduces the risk of mechanical damage.

[0015] Advantageously, the first stopper structure and / or the second stopper structure can be connected to at least one reinforced area which may be located outside an active movable structural layer of the membrane.

[0016] A first reinforced area can, for example, be arranged on one of the wall structures to connect the first stopper structure. A second reinforced area can, for example, be arranged in a central area of ​​the membrane to connect the second stopper structure to this second reinforced area.

[0017] The active structural layer of the membrane is the movable, flexible area of ​​the membrane. The two wall structures, as well as a reinforced area in the middle of the membrane, can be rigid and are therefore located outside the active structural layer of the membrane.

[0018] This arrangement therefore minimizes the risk of damage to the active structural layer of the membrane due to the mechanical stresses between the stopper structures and the membrane, thus increasing the longevity and functionality of the transducer.

[0019] Advantageously, the first stopper structure can be mounted as a separate component on one or both wall structures of the MEMS transducer and / or the second stopper structure can be mounted as a separate component on a reinforced area, for example in a middle area of ​​the membrane.

[0020] A first stopper structure can be connected to a wall structure, for example, by bonding. A second stopper structure can be connected to the reinforced area, for example, in the middle of the membrane, also by bonding. This limits the upward movement of the membrane in a direction perpendicular to the plane of the membrane by the first stopper structure. The opposite downward movement of the membrane is consequently limited by the second stopper structure.

[0021] This consequently allows for more flexible design and adaptation to specific application requirements, thus increasing the effectiveness and adaptability of the transducer. The stopper structures can be attached, for example, by bonding.

[0022] Advantageously, the membrane can have a circular or rectangular shape.

[0023] This allows the acoustic properties of the transducer to be optimized, resulting in improved sound reproduction and efficiency.

[0024] Advantageously, the MEMS transducer can have at least one further reinforced area as a stop for the first stopper structure, preferably in the middle area of ​​the membrane, and / or one further reinforced area as a stop for the second stopper structure, preferably on one or both wall structures.

[0025] This improves the mechanical stability through the reinforced areas acting as stops for the stopper structures, thus extending the service life of the MEMS transducer.

[0026] Advantageously, the membrane can be driven by piezoelectric layer stacks.

[0027] This enables precise and energy-efficient control of the diaphragm, expanding the performance and application range of the transducer. The piezoelectric layer stacks can, for example, be designed as concentric rings, thus ensuring uniform control of the diaphragm.

[0028] Advantageously, the piezoelectric layer stacks can be operated in opposite polarity to achieve an S-shaped deflection of the membrane.

[0029] This results in improved control over the movement of the diaphragm, leading to higher precision and improved acoustic performance.

[0030] Advantageously, the first and second stopper structures can be aligned in a direction perpendicular to a plane of the membrane. The two stopper structures can also be arranged in the same plane and / or made from the same material layer.

[0031] This ensures effective limitation of the maximum diaphragm deflection. Manufacturing both stopper structures in the same plane, i.e., in the same machining step, accelerates the manufacturing process and saves resources. This also ensures that both stopper structures are produced with the same precision and reliability of micromechanical manufacturing. Furthermore, the MEMS transducer with these stopper structures has the advantage that both stopper structures can be located on the same side of the diaphragm, which also represents a significant technical advantage over prior art devices.

[0032] Advantageously, the connection between piezoelectric layer stacks and electrodes for a control unit can be made by rewiring under a bonding frame.

[0033] This ensures a reliable electrical connection that remains stable even under high mechanical stress. The control electronics can be located externally and connected to the MEMS transducer via electrodes such as bond pads. These bond pads can also be manufactured from a single wafer or substrate using conventional micromechanical manufacturing processes as part of a common layout.

[0034] Advantageously, the stopper structures can be realized by an additional wafer which can be bonded to a wafer for the production of the other elements of the MEMS transducer.

[0035] This enables a reliable manufacturing process using known micromechanical manufacturing processes.

[0036] Advantageously, the stopper structures can be realized together with the membrane in an integrated layout on the same common wafer.

[0037] This simplifies the manufacturing process and improves the integration of components, resulting in higher manufacturing efficiency and a lower reject rate.

[0038] Advantageously, the stopper structures can be bonded to the membrane using a wafer bonding process, so that by specifying a thickness of the bond connection, the distance of the maximum deflection between the two stopper structures can be precisely adjusted.

[0039] This allows for precise control of the diaphragm movement, which improves the mechanical robustness of the transducer. The bond connection with the specified thickness can be manufactured very precisely using established micromechanical manufacturing processes.

[0040] Advantageously, the movement of the membrane in the first direction can be limited by two stopper structures, wherein the two stopper structures can preferably be designed as beams, each of which can be connected to wall structures at opposite edges of the membrane, wherein the movement of the membrane in the second direction can be limited by further two stopper structures, wherein the further two stopper structures can preferably be designed as beams connected to a common reinforced, preferably nearly circular, area in a central region of the membrane, wherein a first orientation of the two stopper structures for limiting in the first direction can preferably be arranged perpendicular to a second orientation of the further two structures for limiting in the second direction of the movement of the membrane.

[0041] This ensures reliable control of the membrane's deflection in the first direction by the first two stopper structures striking the opposite edges of the membrane, and of the membrane's deflection in the second direction by the second two stopper structures.

[0042] Advantageously, the movement of the membrane in the first direction can be limited by four stopper structures, wherein the four stopper structures can preferably be designed as beams, each of which can be connected to wall structures at four edges of the membrane, wherein the movement of the membrane in the second direction can be limited by further four stopper structures, wherein the further four stopper structures can preferably be designed as beams, which can be connected to a common reinforced, preferably rectangular, area in a central area of ​​the membrane and can preferably be arranged in the form of a cross.

[0043] This ensures improved control of the membrane deflection in the first direction by the first four stopper structures and in the second direction by the second four stopper structures.

[0044] Advantageously, the stopper structures can be aligned in two opposite directions perpendicular to the membrane in a rest position to limit the deflection of the membrane in both directions.

[0045] This ensures a uniform and controlled maximum deflection of the diaphragm, resulting in mechanical robustness and a longer service life.

[0046] Advantageously, the active structure of the membrane can have an additional reinforcing layer to increase the mechanical stability of the membrane.

[0047] This makes the membrane more resistant to mechanical influences and wear, which extends the lifespan of the sound transducer.

[0048] Advantageously, the MEMS transducer can be an ultrasonic sensor, a MEMS-based loudspeaker, a MEMS-based microphone and / or any other MEMS-based unit where precise control of the diaphragm deflection is required.

[0049] This expands the application range of the transducer and improves its suitability for a wide variety of technical and commercial applications. For example, the ultrasonic sensor can be used as a parking sensor for a motor vehicle.

[0050] Advantageously, the MEMS transducer can be equipped with an integrated sensor that monitors the actual deflection of the diaphragm in real time.

[0051] This enables precise feedback on the membrane dynamics, which optimizes the control and regulation of the transducer, leading to improved acoustic performance and device reliability.

[0052] Advantageously, the MEMS transducer can be designed with a modular construction, which allows individual components such as the diaphragm or the stopper structures to be easily replaced or modified.

[0053] This simplifies the maintenance and adaptation of the transducer to specific application conditions, which extends the lifespan of the device and reduces operating costs.

[0054] Advantageously, the MEMS transducer can be designed in such a way that it exhibits high temperature and humidity resistance. This is achieved through the use of temperature- and humidity-resistant materials and a sealed housing design.

[0055] This makes the sound transducer particularly suitable for use in harsh environments, expanding its applicability in industrial and outdoor applications.

[0056] A further object of the invention is a method for manufacturing the MEMS transducer described above, comprising the following steps: providing a wafer with at least one membrane between at least two wall structures, applying at least one first stopper structure to at least one of the wall structures, wherein the first stopper structure limits the movement of the membrane in a first direction, applying at least one second stopper structure to the membrane, wherein the movement of the membrane is limited in an opposite second direction, wherein the stopper structures and the membrane are manufactured in an integrated layout on the same wafer.

[0057] This allows for a high level of integration in the manufacturing process using conventional micromechanical manufacturing processes. Brief description of the drawings

[0058] The invention is explained with reference to the following drawings: Fig. 1 a schematic representation of a MEMS sound transducer; Fig. 2 a schematic representation of a MEMS transducer in top view with two stopper structures and four stopper structures per direction of movement; Fig. 3 three representations of different modes of embodiment from Fig. 1; Fig. 4 a schematic sectional view of an alternative embodiment of the MEMS sound transducer; Fig. 5 three representations of different modes of embodiment from Fig. 4; Fig. 6 A schematic representation to illustrate the manufacturing process of the MEMS sound transducer 1 from Fig. 1; Fig. 7 a schematic representation to illustrate a manufacturing process of the embodiment of the MEMS sound transducer 1 made of Fig. 4. Examples of implementation

[0059] Fig. Figure 1 shows a schematic representation of a MEMS transducer 1 comprising a diaphragm 2, which is positioned between a first wall structure 3 and a second wall structure 4, a first stopper structure 5, which is connected to the first wall structure 3 by means of a first bond 6, wherein the first stopper structure 5 limits the movement of the diaphragm 2 in a first direction 7 upwards along a y-axis, as indicated by arrow 8. A second stopper structure 9 is connected to the diaphragm 2 in a central region 11 of the diaphragm 2 by means of a second bond 10, wherein the movement of the diaphragm in an opposite second direction downwards along the y-axis, as indicated by arrow 12. A reinforced region 13 is arranged on an underside of the diaphragm 2.The reinforced area 13 can be rigid, allowing the remaining flexible areas of the active structural layer of the diaphragm 2 to control the diaphragm's movement. Adding the reinforced area 13 enhances the mechanical stability of the diaphragm 2, thus improving the longevity of the MEMS transducer 1. A first piezoelectric layer stack 14, in the form of a larger ring, and a second piezoelectric layer stack 15, in the form of a smaller concentric ring, are arranged on one upper surface of the diaphragm 2. By activating the two layer stacks 14 and 15, the diaphragm 2 can be made to vibrate, either to generate sound waves of specific frequencies as a loudspeaker or to capture sound waves and convert them into electrical signals as a microphone.The piezoelectric layer stacks 14, 15 are electrically connected to electrodes, such as bond pads 17, for connecting an external control unit by means of a rewiring 16. The second stopper structure 9 is symmetrically connected to the top of the membrane 2 and the reinforced area 13 to the bottom of the membrane 3 relative to an axis of symmetry 18 of the circular membrane 2.

[0060] Fig. Figure 2 shows a schematic representation of the embodiment. Fig. Figure 1 in the left-hand figure shows a top view, wherein the wall structures 3 and 4 are part of a frame 19 that encloses a circular membrane 2, and the two stopper structures for limiting the movement of the membrane 2 in the first direction 7 are designed as a first beam 20 projecting from the left to the center of the membrane 2, and as a second beam 21 projecting from the right to the center of the membrane 2. The beam 20 is connected to the first wall structure 3 and the beam 21 is connected to the second wall structure 4 at the edge of the circular membrane 2.The two stopper structures for limiting the movement of the membrane 2 in the second direction 12 are designed as a first beam 22, which projects upwards from a circular reinforced area 23 in the center of the membrane 2 to an upper edge 24 of the membrane 2, and as a second beam 25, which projects downwards from the circular reinforced area 23 to a lower edge 26 of the membrane 2. In this way, the movement of the membrane 2 is precisely limited both in the first direction 7 by the beams 20 and 21 and in the opposite second direction 12 by the beams 22 and 25.

[0061] The figure on the right shows an alternative embodiment, in which the movement of the membrane 2 in the first direction 7 is limited by four stop structures: a first beam 27 projecting from the left towards the center, a second beam 28 projecting from the right towards the center, a third beam 29 projecting from above towards the center, and a fourth beam 30 projecting from below towards the center. The movement of the membrane 2 in the opposite second direction 12 is also limited by four stop structures: a first beam 31 projecting to the left from the center, a second beam 32 projecting to the right from the center, a third beam 33 projecting upwards from the center, and a fourth beam 34 projecting downwards from the center. The four beams 31-34 are connected to a rectangular reinforced area 35 and arranged in the shape of a cross.In this embodiment, the movement of the membrane 2 is therefore controlled and limited in the first direction 7 by the beams 27-30 and in the opposite direction 12 by the beams 31-34.

[0062] Fig. Figure 3 shows, in the three left-hand illustrations, different modes of the embodiment from Figure 1, wherein a transducer plate 41 for amplifying the sound waves is arranged on a column 40 of the second stopper structure 9. In the uppermost left illustration, the diaphragm 2 of the MEMS transducer 1 is not deflected. In the middle left illustration, the diaphragm of the MEMS transducer 1 is deflected upwards in the direction of the y-axis, with the diaphragm 2 coming into contact with a stop surface 42 of the first stopper structure 5 above the amplified area 13, thereby limiting the upward movement of the diaphragm 2. In the lowermost left illustration, the diaphragm 2 is deflected downwards, with the second stopper structure 9 coming into contact with a second stop surface 43 of the second wall structure 4, thereby limiting the downward movement of the diaphragm 2 in the opposite direction.

[0063] The three illustrations on the right schematically depict different modes of an alternative embodiment, wherein the first stopper structure 5 and the second stopper structure 9 are attached to the underside 44 of the diaphragm 2 by means of bond connections 45 and 46, and wherein the first wall structure 3, the second wall structure 4, and the reinforced area 13 in the center of the diaphragm 2 are attached to the upperside 47 of the diaphragm 2, with the transducer plate 41 being connected to the reinforced area 13. In the upper right illustration, the diaphragm 2 is not deflected.In the middle right illustration, the membrane 2 is deflected upwards in the y-direction, with the second stopper structure 9 striking a stop surface 48 under the second wall structure 4 and thereby limiting the upward movement in the y-direction; in the lower right illustration, the membrane is deflected downwards in the opposite direction, with the first stopper structure 5 striking a stop surface 49 under the reinforced area 13 and thereby limiting the downward movement of the membrane 2.

[0064] Fig. Figure 4 shows a schematic sectional view of an alternative embodiment of the MEMS transducer 1, wherein the first stopper structure 5 and the second stopper structure 9 are manufactured as components of an active wafer 50 or substrate. The membrane 2, the first wall structure 3, the second wall structure 4, and the reinforced area 13 are formed in a single process step from a second wafer 51 or substrate, or from layers deposited on the first substrate 50. The individual piezoelectric layer stacks 14 and 15 are attached to a bottom surface 52 of the second wafer 51 of a layer stack or even a single layer, and are connected to the bond pads or solder balls 17 by means of the rewiring 16. This embodiment can be manufactured particularly efficiently and quickly using conventional micromechanical manufacturing processes.

[0065] Fig. Figure 5 shows different modes of embodiment in the three illustrations on the left. Fig. 4. In the upper left illustration, the membrane 2 is not deflected. In the middle illustration, the membrane is deflected upwards in the y-direction, with the first stopper structure 5 abutting the stop surface 49 on the reinforced area 13 of the membrane 2, thereby limiting the upward movement of the membrane 2. In the lower left illustration, the membrane 2 is deflected downwards in the opposite direction, with the second stopper structure 9 abutting the stop surface 48 on the second wall structure 4, thereby limiting the downward movement of the membrane 2.

[0066] The transducer plate 41 is connected centrally to the second stopper structure 9 and consequently transmits the movement of the membrane 2 to the transducer plate 41.

[0067] In the right-hand representations of the Fig. Figure 5 shows various modes of an alternative embodiment, wherein the first stopper structure 5 and the second stopper structure 9 are realized in a lower layer of the substrate, and the first wall structure 3, the second wall structure 4, and the reinforced area 13 are realized in the center of an upper layer of the substrate. The transducer plate 41 is connected centrally to the reinforced area 13. In the upper right illustration, the membrane 2 is not deflected. In the middle right illustration, the membrane 2 is deflected upwards, with the second stopper structure 9 connected to the reinforced area 13 and abutting the first wall structure 3, thus limiting the upward movement of the membrane 2 in the y-direction.In the lower right illustration, the membrane 2 is deflected downwards, with the first stopper structure 5 connected to the second wall structure 4 and striking a stop surface of the middle area 13, thus limiting the downward movement of the membrane 2.

[0068] Fig. Figure 6 shows a schematic representation to illustrate the manufacturing process of the MEMS sound transducer 1. Fig. 1. In process step a), a silicon oxide layer 60 and a thick polysilicon layer 61 are first deposited onto a wafer 62, which later represents the active wafer (substrate 2). The membrane 2 is later formed from the polysilicon layer 61.

[0069] In process step b), the piezoelectric layer stacks 14, 15 are subsequently deposited and structured with the piezoelectric material, the required electrode materials or bond pads 17, and, if necessary, further layers, such as barrier layers. In the case of a circular membrane, the piezoelectric layer stacks 14, 15 would be concentric rings, as described above. Furthermore, the rewiring 16 is applied. Additionally, the material for subsequent wafer bonding is deposited and structured for the bond connections 6, 10. The thickness of the bond connections 6, 10 defines the distance between the wafers and thus also the distance between the two stopper structures 5, 9 and the corresponding contact surfaces, thereby also determining the maximum deflection of the membrane 2.

[0070] In process step c), the bond compounds 6, 10 for wafer bonding are deposited and structured on the later stopper wafer (substrate 1).

[0071] In process step d), structures and recesses are etched into the wafer material, defining the subsequent distance between the two stopper structures 5 and 9, ensuring that the stopper structures 5 and 9 do not touch the sensors. Both structures defining the subsequent distance between the stopper structures 5 and 9 and recesses ensuring that the stopper structures 5 and 9 cannot touch either the membrane 2 or the piezoelectric layers 14 and 15 are etched.

[0072] In process step e), substrate 1 is turned over and bonded to substrate 2 and then thinned back to the final thickness, which also defines the thickness of the two stopper structures and 5, 9.

[0073] In process step f), the back side of substrate 2, the active wafer, is structured. The surface of membrane 2 with etch stop is etched from the back side onto the originally deposited silicon oxide. In the center of membrane 2, a reinforced area 13 is created via a shorter etching process. This area stiffens the membrane 2 and thus creates a stable surface on which the first stop structure 5 can strike during operation.

[0074] Finally, in process step g), the top surface of the MEMS transducer 1 is structured. Here, the stopper structures 5, 9 are etched away from each other and from the second wall structure 4, allowing them to move.

[0075] Fig. Figure 7 shows a schematic representation to illustrate a manufacturing process of the embodiment of the MEMS sound transducer 1. Fig. 4.

[0076] In process step a), the shape of depressions 71 under the membrane is defined on a silicon wafer 70 by means of a clever sequence of silicon oxide and polysilicon depositions and structuring (for example, a manufacturing process as described in patent DE102016200494 A1 or DE102015206996 A1 is used).

[0077] In process step b), small openings 72 are produced on an upper surface 73 by means of etching in order to provide access to the depressions 71 and to clear these depressions 71 by means of a sacrificial layer etching process.

[0078] In process step c), these openings 72 are first closed again by a further polysilicon deposition. This is followed by the deposition of the piezoelectric layer stacks 14, 15, their structuring, and the application of the rewiring 16 and bond pads 17. Fig. 4.

[0079] In process step d), the wafer is first ground to a target thickness from the back side and then structured by etching to expose the bars of the two stopper structures 5, 9. In the last step, the silicon oxide can optionally be removed from the depressions 71. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 10129651 B2

[0002] CN 218041775U

[0003] DE 102016200494 A1

[0076] DE 102015206996 A1

[0076]

Claims

[1] MEMS sound transducer (1), comprising: a membrane (2) which is located between at least two wall structures (3, 4), at least one first stopper structure (5) which is directly or indirectly connected to one of the wall structures (3) and limits the movement of the membrane (2) in a first direction (7), at least a second stopper structure (9) that is directly or indirectly connected to the membrane (2) and limits the movement of the membrane (2) in an opposite second direction (12), wherein the stopper structures (5, 9) are realized within the MEMS sound transducer (1) and are manufactured using micromechanical manufacturing processes. [2] MEMS transducer according to claim 1, wherein the first stopper structure (5) and / or the second stopper structure (9) is connected to at least one reinforced area (13) located outside an active structural layer (14) of the membrane (2). [3] MEMS transducer according to one of the preceding claims, wherein the first stopper structure (5) is mounted as a separate component on one or both wall structures (3, 4) of the MEMS transducer (1) and / or the second stopper structure (9) is mounted as a separate component on a reinforced area (13), for example in a central area of ​​the membrane (2). [4] MEMS transducer according to one of the preceding claims, wherein the MEMS transducer (1) has at least one further reinforced area (13) as a stop for the first stopper structure (5), preferably in the middle area of ​​the membrane (2), and / or one further reinforced area (13) as a stop for the second stopper structure (9), preferably on one or both wall structures (3, 4). [5] MEMS sound transducer according to one of the preceding claims, wherein the membrane (2) is driven by piezoelectric layer stacks (14, 15). [6] MEMS sound transducer according to claim 5, wherein the piezoelectric layer stacks (14, 15) are operated in opposite polarity to achieve an S-shaped deflection of the membrane (2). [7] MEMS sound transducer according to any one of the preceding claims 1-6, wherein the first stopper structure (5) and the second stopper structure (9) are aligned in a direction perpendicular to a plane of the membrane (2), wherein the two stopper structures (5, 9) are arranged in the same plane and / or are made from the same layer of material. [8] MEMS transducer according to any of the preceding claims 1-7, wherein the stopper structures (5, 9) are realized by an additional wafer (50) which is attached or bonded to a wafer (51) for the manufacture of the other elements of the MEMS transducer (1). [9] MEMS sound transducer according to any of the preceding claims 1-6, wherein the stopper structures (5, 9) together with the membrane (2) are realized in an integrated layout on the same common wafer. [10] MEMS sound transducer according to one of the preceding claims, wherein the stopper structures (5, 9) are bonded to the membrane (2) by means of a wafer bonding process, so that by specifying a thickness of the bond connection (6, 10) a distance of the maximum deflection between the two stopper structures (5, 9) can be precisely adjusted. [11] MEMS sound transducer according to any one of the preceding claims 1-10, wherein the movement of the membrane (2) in the first direction (7) is limited by two stopper structures (20, 21), wherein the two stopper structures are preferably designed as beams (20, 21) which are each connected to wall structures (3, 4) at opposite edges of the membrane (2), wherein the movement of the membrane (2) in the second direction (12) is limited by further two stopper structures (22, 25), wherein the further two stopper structures are preferably designed as beams (22, 25) which are connected to a common reinforced, preferably nearly circular, area (23) in a central area of ​​the membrane (2), wherein a first orientation of the two stopper structures (20, 21) for limiting in the first direction is preferably perpendicular to a second orientation of the further two structures (22,25) is arranged to limit the movement of the membrane (2) in the second direction (12). [12] MEMS sound transducer according to any one of the preceding claims 1-10, wherein the movement of the membrane (2) in the first direction (7) is limited by four stopper structures (27-30), wherein the four stopper structures are preferably designed as beams (27-30) which are each connected to wall structures (3, 4) at four edges of the membrane (2), wherein the movement of the membrane (2) in the second direction (12) is limited by further four stopper structures (31-34), wherein the further four stopper structures are preferably designed as beams (31-34) which are connected to a common reinforced, preferably rectangular, area (35) in a central area of ​​the membrane (2) and are preferably arranged in the form of a cross. [13] MEMS sound transducer according to one of the preceding claims, wherein the active structure of the membrane (2) has an additional reinforcing layer to increase the mechanical stability of the membrane. [14] MEMS transducer according to any of the preceding claims, wherein the MEMS transducer (1) is an ultrasonic sensor, a MEMS-based loudspeaker, a MEMS-based microphone and / or any other MEMS-based unit in which precise control of the diaphragm deflection is required. [15] Method for manufacturing a MEMS sound transducer according to any one of claims 1 to 14, comprising the steps: Providing a wafer with at least one membrane (2) between at least two wall structures (3, 4), Attaching at least one first stopper structure (5) to at least one of the wall structures (3), wherein the first stopper structure (5) limits the movement of the membrane (2) in a first direction (7), Attaching at least one second stopper structure (9) to the membrane (2), limiting the movement of the membrane (2) in an opposite second direction (12), wherein the stopper structures (5, 9) and the membrane (2) are manufactured in an integrated layout on the same wafer.

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