Microelectromechanical transducer

Abstract

Microelectromechanical transducer (100; 600; 700), comprising a movable membrane (104; 204; 304; 404; 504; 604; 704) which has a corrugated section (106; 206; 606; 706) with at least one trough (110; 210; 410; 610; 710) and at least one crest (108; 208; 408; 608; 708), wherein in at least one trough (110; 210; 410; 610; 710) and at least one crest (108; 208; 408; 608; 708) a piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) is provided, wherein each piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) has a piezoelectric layer (114; 214; 314; 414; 514) and at least one electrode (116; 216, 224; 316, 317; 416, 424; 516, 517; 616a, 616b-T, 616b-B, 616c, 624a, 624b, 624c) in electrical contact with the piezoelectric layer (114; 214; 314; 414; 514), wherein the membrane (104; 204; 304; 404; 504; 604; 704) is designed as a planar component which has a significantly greater extent in a first and a second spatial direction (X, Y), which are orthogonal to each other, than in a third spatial direction (A), which is orthogonal to the first and the second spatial direction (X, Y) and defines an axial direction (A) of the membrane (104; 204; 304; 404; 504; 604; 704), wherein the membrane (104; 204; 304; 404; 504; 604; 704) has a neutral fiber (NF) in the corrugated section (106; 206; 606; 706) which is located in the axial direction (A) between the at least one wave crest (108; 208; 408; 608; 708) and the at least one wave trough (110; 210; 410; 610; 710), wherein the piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) provided at the at least one wave crest (108; 208; 408; 608; 708) and the piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) provided in the at least one wave trough (110; 210; 410; 610; 710) are arranged relative to each other without overlap, wherein at least one wave crest (108; 208; 408; 608) and at least one wave trough (110; 210; 410; 610) are provided consecutively in a radial direction (R) of the membrane (104; 204; 304; 404; 504; 604). or wherein at least one wave crest (208; 408; 708) and at least one wave trough (210; 410; 710) are provided consecutively in a circumferential direction (C) of the membrane (204; 304; 404; 504; 704).

Description

[0001] Various embodiments relate generally to a microelectromechanical transducer and a method for manufacturing a microelectromechanical transducer.

[0002] Microelectromechanical transducers play a central role in modern electronics as both sensors and actuators and find a wide variety of applications, such as microphones, loudspeakers, pressure sensors or acceleration sensors.

[0003] Microelectromechanical transducers can have a diaphragm which, depending on whether the transducer is designed as a sensor or an actuator, can be moved passively or actively. In the case of a microelectromechanical transducer designed as a sensor, the diaphragm can be moved passively, for example, by sound or acceleration to be detected. From the movement of the diaphragm, characteristics of the quantity to be detected, such as a sound frequency, a sound amplitude, or a temporal acceleration profile, can be determined. In the case of a microelectromechanical transducer designed as an actuator, the diaphragm can be moved actively, for example, to generate sound in a loudspeaker.

[0004] Such membranes of microelectromechanical transducers can be formed, at least in sections, from piezoelectric material. In the event of passive displacement of the membrane, an electrical voltage is induced in this material, which can be read out by a suitable readout circuit to determine the characteristics of a quantity to be detected. Alternatively, in the case of an actuator, an electrical voltage can be applied to the membrane to induce a controlled deformation of the membrane, for example, to generate sound.

[0005] With piezoelectric membranes used in conventional microelectromechanical transducers, the general problem is that either applying an electrical voltage to the membrane does not produce a defined deformation, or that due to internal electrical short circuits in the piezoelectric membrane, the achievable sensitivities with such microelectromechanical sensors are very low. This will be explained below by reference to Fig. 1 will be explained.

[0006] Fig. Figure 1 shows a section of a conventional piezoelectric membrane 10 used in a microelectromechanical transducer. The membrane is attached at one end 12 and, as indicated by its curved shape, can be displaced by a physical quantity to be detected, for example, sound. The membrane 10 has a piezoelectric layer 14 and, on opposite sides of the piezoelectric layer 14, electrodes 16, 18 for tapping off an electrical voltage induced in the piezoelectric layer 14. The dashed line in Figure 1 indicates the position of the electrodes. Fig. 1. The neutral fiber NF of the membrane 10. The neutral fiber NF is the plane of the membrane 10 whose length does not change when the membrane 10 is displaced. In this plane, a displacement of the membrane 10 therefore does not result in any tensile or compressive stress.

[0007] As in Fig. As indicated in Figure 1, the neutral fiber NF divides the membrane 10 into two areas, one in Fig. 1 upper area A, which, as indicated by the arrows in this area, is used in the Fig. The displacement of membrane 10 shown in section 1 is subjected to a tensile load, and a [unclear] in [unclear] Fig. 1 lower area B, which, as indicated by the arrows in this area, is used in the Fig. The displacement of the membrane 10 shown in Figure 1 is subjected to a pressure load. Due to the different loads in areas A and B, the electric fields EA and EB induced in these areas by a deflection of the membrane 10 have opposite signs, so that the net electrical voltage obtainable via electrodes 16, 18 is very low, which considerably limits the achievable sensitivity. Likewise, applying an electrical voltage to electrodes 16, 18 does not produce a defined deformation of the membrane 10.

[0008] Furthermore, a fundamental challenge in the production of microelectromechanical transducers is generally the creation of well-defined membrane shapes to ensure reproducible behavior. This also applies to microelectromechanical transducers with piezoelectric membranes. A significant problem arises from the mechanical stresses to which such membranes are subjected, which can impair reproducible behavior. These mechanical stresses can have intrinsic causes, such as thermal or mechanical loads during the manufacturing process. Alternatively or additionally, such mechanical stresses can result from differing coefficients of thermal expansion of various components within a microelectromechanical transducer, which can be transferred to the membrane.

[0009] Examples of transducers are known from the publications US 2011 / 0 064 250 A1, JP 2015 - 100 093 A JP S48 - 80 289 A and JP S60 - 160 299 A.

[0010] The task is therefore to provide a microelectromechanical transducer with well-defined electrical and mechanical properties.

[0011] According to a first aspect of the invention, a microelectromechanical transducer according to claim 1 is provided. According to a further aspect of the invention, a method for manufacturing a microelectromechanical transducer as defined in claim 20 is provided.

[0012] Various embodiments are described below with reference to the accompanying drawings. These are: Fig. 1 a view of a section of a conventional piezoelectric membrane, Fig. 2 a top view of a piezoelectric membrane of a microelectromechanical transducer according to an exemplary embodiment, Fig. 3 to 7 sectional views of a section of piezoelectric membranes of microelectromechanical transducers according to various embodiments, Fig. 8 A view of the front side of a piezoelectric membrane of an exemplary microelectromechanical transducer, Fig. 9 a view of a reverse side of the in Fig. 8 piezoelectric membrane shown, Fig. 10 a top view of a piezoelectric membrane of a microelectromechanical microphone according to a further exemplary embodiment, Fig. 11 a schematic representation of a microphone which has a microelectromechanical transducer, Fig. 12 to 17 schematic diagrams illustrating an exemplary procedure for manufacturing an exemplary microelectromechanical transducer, and Fig. 18 a flowchart of an exemplary procedure for manufacturing an exemplary microelectromechanical transducer.

[0013] The term "exemplary" is used here to mean "serving as an example, a specimen, or for illustration." Each embodiment or configuration described here as "exemplary" should not necessarily be understood as preferred or advantageous over other embodiments or configurations.

[0014] In the drawings, the same reference symbols refer to the same parts in the different views. The drawings primarily serve to illustrate the essential principles of this disclosure and are therefore not necessarily to scale.

[0015] In Fig. Figure 2 shows an exemplary microelectromechanical transducer 100. This transducer can have a holder 102 and a movable diaphragm 104 attached to the holder 102. At least part of the diaphragm 104 can be made of piezoelectric material. By moving the diaphragm 104, an electrical voltage can be induced in the piezoelectric material, which can be measured by a suitable readout circuit. From the measured electrical voltage, characteristics of a quantity to be detected, such as sound or acceleration, can be determined. Alternatively, an electrical voltage can be applied to the diaphragm 104 to move it, for example, to generate sound.

[0016] If the transducer 100 is configured as an accelerometer or as part of an accelerometer, an inertial mass 103 can be provided on the diaphragm 104, for example on a central section of the diaphragm 104, in order to amplify the force exerted on the diaphragm 104 by an acceleration to be detected. The inertial mass 103 can be separate from the diaphragm 104. It can, for example, be made of a semiconductor material, such as silicon.

[0017] As in Fig. As indicated in Figure 2, the diaphragm 104 can be attached to the holder 102 around its perimeter 104R. The diaphragm 104 can be designed as a closed component, such that an uninterrupted connection exists along the diaphragm 104 between any two points of the perimeter 104R. The diaphragm 104 can thus be free of fluid passage openings, which can otherwise act as a noise source when a fluid, such as a gas, flows through such an opening. The absence of a fluid passage opening in the diaphragm 104 can be a significant advantage over a piezoelectric diaphragm, which has a plurality of cantilevers that can be deflected independently of one another.A closed diaphragm 104 is also particularly robust, since any free-floating elements are especially sensitive to extreme mechanical stresses, which, for example, can lead to damage to a free-floating diaphragm in the event of an impact. However, it should not be ruled out that a diaphragm 104 described here may have one or more openings to minimize resistance that may be caused by gas, such as air, accumulating on one side of the diaphragm 104. This ensures a high degree of compliance of the diaphragm 104.

[0018] The in Fig. The membrane 104 shown in Figure 2 can be designed as a planar component. "Planar" here essentially means that the membrane 104 has a significantly greater extent along a first spatial direction X and a second spatial direction Y orthogonal to the first spatial direction X than along a third spatial direction, which is orthogonal to the first spatial direction X and the second spatial direction Y and defines an axial direction A of the membrane 104.

[0019] The membrane 104 can have a corrugated section 106 with at least one crest 108 and at least one trough 110, or with a plurality of crests 108 and a plurality of troughs 110. The crests 108 and the troughs 110 are arranged alternately in a radial direction R of the membrane 104. The crests 108 and / or troughs 110 can have a circular or circular-segment shape and be arranged concentrically, for example around a center point M of the membrane 104. A circular-segment shape of the crests 108 and troughs 110 (not shown) allows, for example, radial routing of supply lines on the membrane 104.

[0020] By forming the wave crests 108 and / or wave troughs 110 in a circular or circular segment shape, the membrane 104 is primarily designed to detect a deflection in the circumferential direction C.

[0021] The corrugated section 106 compensates for the mechanical stresses discussed earlier, as it acts as an elastic element capable of absorbing these stresses through stretching or compression. This limits the deformation of the membrane 104 caused by these stresses. As a result, the membrane 104 maintains a well-defined shape and deflects in a well-defined manner, leading to reproducible behavior.

[0022] Furthermore, the corrugated section 106 of the membrane 104 can be used to reduce or eliminate the compensation of induced electric fields discussed at the outset. This will be explained below by reference to Fig. 3 explains which makes a cut through membrane 104 along the in Fig. Line III-III is shown in section 2.

[0023] As in Fig. As shown in Figure 3, a piezoelectric unit cell 112 can be provided at a plurality of wave crests 108 and / or in a plurality of wave troughs 110, or even at each wave crest 108 and / or in each wave trough 110. Each unit cell has a piezoelectric layer 114 and at least one electrode 116 in electrical contact with the piezoelectric layer 114. In the corrugated section 106, the neutral fiber NF of the membrane 104 is located in the axial direction A between the wave crests 108 and the wave troughs 110. This divides the membrane 104 in the axial direction A into two regions, which, in the event of deflection of the membrane 104, are subjected to either a tensile or a compressive load.For example, in the case of a deflection of the membrane 104, the wave crests 108 can be subjected exclusively to tensile stress, while the wave troughs 110 can be subjected exclusively to compressive stress, and vice versa. This results in an electric field with a uniform sign being induced in each wave crest 108 and wave trough 110, so that, unlike the conventional piezoelectric membranes discussed earlier, there is no compensation of the electric field within a piezoelectric layer 114, which would limit the obtainable net electrical voltage. Ultimately, this allows a higher electrical voltage U to be obtained for a given deflection of the membrane 104 compared to conventional piezoelectric transducers, thus enabling higher sensitivity compared to conventional microelectromechanical transducers.Furthermore, a defined deflection of the membrane 104 can be achieved by applying an electrical voltage to the respective electrodes 116.

[0024] The in Fig. The 3 piezoelectric unit cells 112 shown can have only a single electrode 116, which can be provided on the same side of the respective piezoelectric layers 114. This design can make the fabrication of the microelectromechanical transducer 100 particularly simple, since the electrodes 116 can be simultaneously vapor-deposited and / or structured.

[0025] In principle, any electrically conductive material is suitable as a material for the electrodes 116, for example a metal such as aluminum. The piezoelectric layers 114 of the respective piezoelectric unit cells 112 can be made, for example, of aluminum nitride (AlN), zinc oxide (ZnO), or lead zirconate titanate (ZnO).

[0026] As in Fig. As indicated in Figure 3, the electrodes 116 of the piezoelectric unit cells 112 provided at the wave crests 108 can be electrically connected in parallel by a conductor 118, while the electrodes 116 of the piezoelectric unit cells 112 provided in the wave troughs 110 can be electrically connected in parallel by a conductor 120. This allows the electrical potentials induced in the respective piezoelectric unit cells 112 at the wave crests 108 and in the wave troughs 110 to be tapped off via the respective electrode 116 and then summed, thus enabling the extraction of a high net electrical voltage U.

[0027] The piezoelectric layers 114 of the respective piezoelectric unit cells 112 can be formed in one piece. As in the Fig. 2 and Fig. As shown in Figure 3, the piezoelectric layers 114 of two adjacent piezoelectric unit cells 112 can be integrally connected by connecting sections 122, which extend essentially in the axial direction A. Due to the integral formation of the piezoelectric layers 114, the membrane 104 as a whole can be manufactured in a simple manner, since the piezoelectric layers 114 of the piezoelectric unit cells 112 can be produced simultaneously with the production of the corrugated section 106.

[0028] The following will be referred to Fig. 4. Another exemplary embodiment is described. The same components or component sections are used as in [reference to relevant section]. Fig. 3 with the same reference symbols as in Fig. 3 will be provided, however, compared to Fig. 3 increased by 100. For the sake of simplicity, the description of the in Fig. The embodiment shown in section 4 differs only in its differences from the one shown in Fig. 3. The embodiment shown is described in detail, and its description is expressly referenced.

[0029] The in Fig. Membrane 204 shown in section 4 differs from the one in Fig. The membrane 104 shown in Figure 3 is distinguished simply by the fact that it has a continuous electrically conductive layer 224 on the side of the piezoelectric layer 214 opposite the electrodes 216 of the piezoelectric unit cells 212. This layer 224 can, for example, be made of a metal. The electrically conductive layer 224 can, for example, ensure a defined field profile for an electric field induced in a piezoelectric unit cell 212. Additionally, the electrically conductive layer 224 can serve as a reference electrode to provide a reference potential VRef for the piezoelectric unit cells 212 at both the wave crests 208 and the wave troughs 210.This allows a differential detection scheme to be implemented in the case of a sensor, such as a microphone, in which the electrical voltage induced at the wave crests 208 in the piezoelectric unit cells 212 and the electrical voltage induced at the wave troughs 210 in the piezoelectric unit cells 212 can be subtracted from each other in order to eliminate common noise contributions. This ultimately allows for high sensitivity.

[0030] Each piezoelectric unit cell 212 in Fig. 4 thus has an electrode 216, 224 on opposite sides of its piezoelectric layer 214. The electrodes 216 on a first side of the piezoelectric layers 214 are formed separately from each other, while the electrodes 224 on a second side of the piezoelectric layers 214 opposite the first side are formed integrally. The corrugated section 206 of the in Fig. The membrane 204 shown in Figure 4 thus has a layered structure, comprising the electrically conductive layer 224 as one layer and the piezoelectric layer 214 as another layer.

[0031] The following will be referred to Fig. 5. Another exemplary embodiment is described. The same components or component sections are used as in [reference to relevant section]. Fig. 3 with the same reference symbols as in Fig. 3 will be provided, however, compared to Fig. 3 increased by the number 200. For the sake of simplicity, the description of the in Fig. The embodiment shown in section 5 differs only in its differences from the one shown in Fig. 3. The embodiment shown is described in detail, and its description is expressly referenced.

[0032] At the in Fig. The membrane 304 shown in Figure 5 can have one or more piezoelectric unit cells 312, or even each piezoelectric unit cell 312, comprising two electrodes 316, 317, each of which is in electrical contact with the associated piezoelectric layer 314. The electrodes 316, 317 of one piezoelectric unit cell 312 are separate from the electrodes 316, 317 of each other piezoelectric unit cell 312. The electrodes 316, 317 of a piezoelectric unit cell 312 are arranged on opposite sides of a piezoelectric layer 314. This configuration ensures a defined path for an electric field induced in a piezoelectric unit cell 312. An electric voltage U1-U5 induced in a specific piezoelectric unit cell 312 can be, as shown in Figure 5, Fig. 5 shown, locally accessed. In the case of the Fig. In the membrane 304 shown in Figure 5, there is thus a plurality of independent voltage sources that can be electrically connected in series to obtain a high output voltage. This allows, for example in the case of a sensor, high detection sensitivity to be achieved.

[0033] The tapping of the induced electrical voltage according to Fig. 5 thus offers an alternative to the one in the Fig. 3 and Fig. The diagram shown in section 4 illustrates this, where the electrodes at the wave crests and the electrodes in the wave troughs are connected in parallel. This offers alternatives that can be individually selected depending on a downstream readout circuit, such as an amplifier, in order to provide, for example, capacitive or impedance matching.

[0034] The following will be referred to Fig. 6. Another exemplary embodiment is described. The same components or component sections are used as in [reference to relevant section]. Fig. 3 with the same reference symbols as in Fig. 3 will be provided, however, compared to Fig. 3 increased by the number 300. For the sake of simplicity, the description of the in Fig. The embodiment shown in 6 differs only in its differences from the one in Fig. 3. The embodiment shown is described in detail, and its description is expressly referenced.

[0035] The in Fig. Membrane 404 shown in Figure 6 differs from membrane 104 according to Figure 6. Fig. 3 in that the majority of piezoelectric unit cells 412 do not have a common piezoelectric layer, but rather different piezoelectric layers 414 which are in electrical contact with a respective electrode 416. The membrane 404, in contrast to the one in Fig. The membrane 104 shown in Figure 3 has a support 426 that differs from the piezoelectric layers 414 and can be made of a non-piezoelectric material, such as a semiconductor material, e.g., silicon. The support 426 has a corrugated shape and thereby defines a plurality of wave crests 408 and a plurality of wave troughs 410.

[0036] Thanks to the support 426 formed from a non-piezoelectric material, the membrane 404 can be produced with a well-defined shape, since the waveform of the corrugated section of the membrane 404 can potentially be produced more precisely from a non-piezoelectric material than from a piezoelectric material, as the growth of piezoelectric materials often exhibits a strong directional dependence.

[0037] The support 426, made of a non-piezoelectric material, also enables electrical decoupling of the majority of piezoelectric unit cells 412, thus preventing crosstalk and any resulting compensation of electric fields induced in different piezoelectric unit cells 412. This ensures a defined behavior of the membrane 404.

[0038] As in Fig. As shown in Figure 6, the membrane 404 can be provided with a one-piece electrode 424 on the side of the carrier 426 facing the piezoelectric unit cells 412, which, as mentioned above, can enable a differential detection scheme, for example, as a common electrode.

[0039] The following will be referred to Fig. 7. Another exemplary embodiment is described. The same components or component sections are used as in [reference to relevant section]. Fig. 6 with the same reference symbols as in Fig. 6 will be provided, however, compared to Fig. 6 increased by the number 100. For the sake of simplicity, the description of the in Fig. The embodiment shown in 7 differs only from the one in Fig. The embodiment shown in section 6 is discussed, and its description is expressly referenced.

[0040] The in Fig. Membrane 504 shown in Figure 7 differs from membrane 404 according to Figure 7. Fig. 6 in that at least one piezoelectric unit cell 512, a plurality of piezoelectric unit cells 512, or even each piezoelectric unit cell 512 has two electrodes 516, 517, which are provided on opposite sides of the respective piezoelectric layers 514 and are each formed separately from the electrodes 516, 517 of each other piezoelectric unit cell 512. This allows the electrical voltages U1-U5 induced in the respective piezoelectric unit cells 512 to be measured, similarly to the method described in Fig. The embodiment shown in section 5 can be read locally. For further details, please refer to the description in [reference to relevant section]. Fig. Reference is made to the embodiment shown in section 5.

[0041] The following will refer to the Fig. 8. Another exemplary embodiment is described. The same components or component sections are used as in [reference to relevant section]. Fig. 2 with the same reference symbols as in Fig. 2 will be provided, however, compared to Fig. 2 increased by the number 500. The one in Fig. The transducer shown in Figure 8 will only be described insofar as it differs from the one shown in Figure 8. Fig. The 2 transducer shown differs, and its description is expressly referenced.

[0042] The in Fig. The transducer 600 shown in Figure 8 has a membrane 604 supported on a holder 602, with a corrugated section 606. The corrugated section 606 has a plurality of wave crests 608 and a plurality of wave troughs 610. These can be, as shown in Fig. As indicated in Figure 8, the piezoelectric units 612 are arranged alternately in a radial direction R of the membrane 604. A piezoelectric unit cell 612 can be provided at each wave crest 608 and in each wave trough, each cell having an electrode provided on one side of the membrane 604.

[0043] As also in Fig. As shown in Figure 8, the corrugated section 606 can be segmented in a circumferential direction C of the membrane 604 into a plurality of circumferential sections 606a-c, for example, into a first, a second, and a third circumferential section 606a, 606b, 606c. Accordingly, the piezoelectric unit cells 612 and the associated electrodes provided at the wave crests 608 and in the wave troughs 610 can also be segmented in the circumferential direction C. In a circumferential section 606a-c of the corrugated section 606, a plurality of electrodes provided at respective wave crests 608 can be electrically connected in parallel. Alternatively or additionally, in a circumferential section 606a-c of the corrugated section 606, a plurality of electrodes provided in respective wave troughs 610 can be electrically connected in parallel.

[0044] As in Fig. As shown in Figure 8, the electrodes 616a provided in the troughs 610a of the first circumferential section 606a of the corrugated section 606 can be electrically connected parallel to each other at one end in the circumferential direction C by a first busbar 617S-1 and at an opposite end in the circumferential direction C by a first connecting rail 617V-1. The first busbar 617S-1 can be configured as a rail extending in the radial direction R, which is arranged between the first and the third circumferential sections 606a, 606c of the corrugated section 606.

[0045] The first connecting rail 617V-1 simultaneously connects the electrodes 616b-B provided at the wave crests 608b in the second circumferential section 606b of the corrugated section 606 electrically in parallel to each other and simultaneously electrically in series with the electrodes 616a in the wave troughs 610a connected electrically in parallel in the first circumferential section 606a of the corrugated section 606.

[0046] The electrodes 616b-T provided in the wave troughs 610b of the second circumferential section 606b of the corrugated section 606 can be connected to each other in parallel by means of a second connecting rail 617V-2, which is located in the circumferential direction C between the second and third circumferential sections 606b, 606c of the corrugated section 606 and extends in the radial direction R.

[0047] The second connecting rail 617V-2 simultaneously connects the electrodes 616c provided at the wave crests 608c in the third circumferential section 606c of the corrugated section 606 in parallel at an end section in the circumferential direction C. The second connecting rail 617V-2 thus provides an electrical series connection between the electrodes 616b-T connected in parallel in the wave troughs 610b of the second circumferential section 606b and the electrodes 616c connected in parallel at the wave crests 608c of the third circumferential section 606c.

[0048] An end of the parallel-connected electrodes 616c in the third circumferential section 606c of the corrugated section 606, opposite the second connecting busbar 617V-2 in circumferential direction C, is electrically connected to a second busbar 617S-2. A total voltage can be tapped from the diaphragm 604 via the first and second busbars 617S-1 and 617S-2.

[0049] The in Fig. The configuration shown in Figure 8, for example, offers a simple and compact way to maximize the electrical voltage that can be generated in the diaphragm 604 by its deflection. Likewise, with this configuration, a defined deflection of the diaphragm 604 can be induced by applying an electrical voltage to the busbars 617S-1 and 617S-2, if the Fig. 8 microelectromechanical transducers 600 shown are designed as an actuator or as part of an actuator.

[0050] As in Fig. As shown in Figure 9, for example, to enable a previously explained differential measurement scheme, a uniform reference electrode 624a-c can be provided on a rear side of the membrane 604 for each circumferential section 606a-c, each of which can be provided with its own connection section 625a-c.

[0051] In Fig. Figure 10 shows an exemplary microelectromechanical transducer 700 according to a further embodiment. The microelectromechanical transducer 700 has a membrane 704 which is fixed to a holder 702 in an edge region 704R. The membrane 704 further has a corrugated section 706 which has a plurality of wave crests 708 and a plurality of wave troughs 710, on each of which a piezoelectric unit cell 712 with a piezoelectric layer and at least one electrode can be provided. In contrast to the one in Figure 10, the microelectromechanical transducer 700 has a corrugated section 706 which has a plurality of wave crests 708 and a plurality of wave troughs 710, on each of which a piezoelectric unit cell 712 with a piezoelectric layer and at least one electrode can be provided. Fig. In the membrane 104 shown in Figure 2, the wave crests 708 and the wave troughs 710 have a substantially radial main extent. The wave crests 708 and the wave troughs 710 are arranged successively and alternately in a circumferential direction C of the membrane 704. Otherwise, the statements relating to the figures in the following apply. Fig. The embodiments shown in 2 to 7 are also applicable to the one described in Fig. 10 transducers 700 shown. This means in particular that the unit cells 712 provided in the wave troughs 710 and at the wave crests 708 are as in the Fig. 3 to 7 are shown and can be electrically interconnected. The sectional views of the Fig. 3 to 7 can therefore be considered sections through the in Fig. 10 Transducer 700 shown along the in Fig. Lines III-VII shown in 10 can be interpreted as follows.

[0052] The 100-700 transducers described here can be used, for example, in microphones, loudspeakers, accelerometers, or pressure sensors. The following section refers to the... Fig. 11 describes an exemplary microelectromechanical microphone 800 in which a previously described transducer is built in. For the sake of simplicity, it is assumed here that this is the one described in Fig. The 2 shown transducer 100 are involved.

[0053] The microphone 800 can have a housing 802 with a sound inlet opening 804, inside of which the transducer 100 is installed. Sound waves S to be detected can enter the interior of the housing 802 through the sound inlet opening 804. As shown in Fig. As indicated in Figure 11, the diaphragm 104 overlaps the sound inlet opening 804, so that sound waves S entering the interior of the housing 802 through the sound inlet opening 804 can directly strike the diaphragm 104. The transducer 100 can be configured to convert characteristics of the sound waves S to be detected, such as a sound frequency or sound pressure, into electrical signals and transmit these via signal lines 806 to a control unit 808. The control unit 808 can evaluate the electrical signals received from the transducer 100 and determine characteristics of the sound waves S to be detected from them. The control unit 808 can, for example, comprise a microprocessor and / or an application-specific integrated circuit (ASIC) and / or a field-programmable gate array (FPGA). A microelectromechanical microphone according to Fig. 11 can, for example, be installed in a mobile communication device, such as a mobile phone, a laptop or a tablet.

[0054] The following is based on the Fig. Figures 12 to 17 describe an exemplary method for manufacturing a microelectromechanical transducer. For the sake of simplicity, only a part of the transducer to be manufactured is shown in these figures.

[0055] The process can include forming a negative mold 1000 for a membrane to be produced, which has a side 1001 complementary to one side of the membrane with at least one wave crest and at least one wave trough.

[0056] The formation of such a negative mold 1000 is in Fig. Figure 12 illustrates this. Here, a sacrificial material layer 1004 can be deposited onto a substrate 1002, in which a plurality of recesses 1006 can subsequently be formed. Alternatively, the plurality of recesses 1006 can be formed both in the sacrificial material layer 1004 and in the substrate 1002. This allows a plurality of wave crests 1010 and a plurality of wave troughs 1012 to be defined, which can have a substantially complementary shape to a corrugated section of a membrane to be produced. The substrate 1002 can, for example, be made of a single-crystal semiconductor material, such as single-crystal silicon. The sacrificial layer 1004 can, for example, be made of an oxide, such as SiO₂. x , be formed. The formation of the recesses 1006 can, for example, be done by etching.

[0057] The deposition of the sacrificial material layer 1004 is optional. In an alternative exemplary process, a sacrificial material layer can be omitted. In such a case, at least one or more recesses for forming at least one wave trough and at least one wave crest can be formed solely in the substrate 1002.

[0058] Subsequently, a membrane can be formed on the negative mold, and a piezoelectric unit cell can be formed in at least one of the wave troughs 1012 and at at least one of the wave crests 1010. For this purpose, as described in Fig. As shown in Figure 13, an electrically conductive layer 1014 is first deposited over a large area onto the negative mold 1000, which also covers the sections of the negative mold 1000 corresponding to the wave crests 1010 and the wave troughs 1012. The electrically conductive layer can, for example, be made of a metal.

[0059] The electrically conductive layer 1014 can then be applied as described in Fig. Figure 14 shows that a piezoelectric layer 1016 can be deposited, for example by sputtering, which in turn defines a plurality of wave troughs 1018 and a plurality of wave crests 1020. Thus, the electrically conductive layer 1014 together with the piezoelectric layer 1016 forms a membrane 1021, which has a side complementary to the negative shape 1000.

[0060] After the membrane 1021 has been formed, an electrode 1022 can be formed in the wave troughs 1018 and at the wave crests 1020, for example by depositing a metal.

[0061] To connect the electrically conductive layer 1014, which can form a reference electrode, the following can then be done as described in Fig. Figure 16 shows an opening 1024 being formed in the piezoelectric layer 1016, in which a contact pad 1026 is placed for contacting the electrically conductive layer 1014, as shown in Fig. As shown in Figure 17, further contact pads 1028 can also be formed on the electrodes 1022 formed on the piezoelectric layer 1016 in order to electrically contact them.

[0062] As further in Fig. As shown in Figure 17, a portion of the substrate 1002 and a portion of the sacrificial layer 1004 can then be removed to form a holder 1030 and to expose the membrane 1021. The transducer formed according to this method essentially has a structure as shown in Figure 17. Fig. 4 up.

[0063] When removing part of the sacrificial layer 1004 and part of the substrate 1002, a [something] with reference to Fig. The inertial mass described in section 2 is formed by not removing the sacrificial layer 1004 and the substrate 1002 in a region of the membrane 1021 that differs from a boundary region. An inertial mass 1032 formed in this way is in Fig. 17 shown with dashed lines. In the exemplary representation according to Fig. 17. The inertial mass 1032 is provided on a corrugated section of the membrane 1021. It can, of course, be arranged similarly to the Fig. 2 be provided in a central area of ​​membrane 1021, which is not corrugated. In Fig. Figure 17 shows only a section of the membrane 1021, which has a corrugated section and an area connected to the holder 1030. Therefore, for the sake of simplicity, an inertial mass provided on a non-corrugated central section of the membrane 1021 is not shown here.

[0064] If, as mentioned above, a sacrificial layer is omitted, then only a part of the substrate can be removed to form a holder and / or an inert mass.

[0065] The method described above can be easily modified to produce the other embodiments described here. For example, if the electrically conductive layer 1016 is omitted, the following can be used: Fig. The membrane 104 shown in Figure 3 can be produced. If, prior to the deposition of the piezoelectric layer 1016, the electrically conductive layer 1014 is structured into a plurality of electrodes in relation to the wave troughs and wave crests, the membrane 1014 shown in Figure 3 can be produced. Fig. The embodiment shown in section 5 can be manufactured.

[0066] In Fig.Figure 18 shows a flowchart of an exemplary procedure for fabricating an exemplary microelectromechanical transducer. This may include: depositing a sacrificial material layer onto a substrate (S100), Forming at least one recess in the sacrificial material layer to form at least one wave crest and at least one wave trough (S200), Deposition of a piezoelectric layer on at least one wave crest and in at least one wave trough (S300), Forming an electrode at at least one wave crest and an electrode in at least one wave trough (S400), Removing part of the sacrificial material layer and substrate to form a holder (S500).

[0067] As mentioned above, the deposition of a sacrificial material layer onto the substrate can be omitted, whereby at least one recess must then be formed in the substrate.

[0068] Numerous exemplary embodiments according to the present disclosure will be described below.

[0069] Example 1 is a microelectromechanical transducer comprising a movable membrane with a corrugated section having at least one trough and at least one crest, wherein a piezoelectric unit cell is provided in at least one trough and at least one crest, each piezoelectric unit cell comprising a piezoelectric layer and at least one electrode in electrical contact with the piezoelectric layer. The membrane can be designed as a planar component which has a significantly greater extent in a first and a second spatial direction, which are orthogonal to each other, than in a third spatial direction, which is orthogonal to the first and the second spatial directions and defines an axial direction of the membrane.The at least one wave crest and the at least one wave trough can be provided successively in a radial direction or in a circumferential direction of the membrane.

[0070] In Example 2, the subject of Example 1 may optionally further exhibit that the corrugated section has a plurality of wave crests and / or a plurality of wave troughs.

[0071] In Example 3, the subject matter of Example 1 or 2 may optionally further include that at least one piezoelectric unit cell has an electrode on only one side of its piezoelectric layer, wherein optionally several piezoelectric unit cells have an electrode on only one side of their respective piezoelectric layers, wherein the electrodes of different piezoelectric unit cells are formed separately from one another.

[0072] In Example 4, the subject of one of Examples 1 to 3 may optionally further have that at least one piezoelectric unit cell has electrodes on opposite sides of its piezoelectric layer.

[0073] In Example 5, the subject matter of Example 4 may optionally further include a plurality of piezoelectric unit cells having electrodes on opposite sides of their piezoelectric layers, wherein the electrodes of the plurality of piezoelectric unit cells on a first side of the piezoelectric layers are formed separately from one another and the electrodes of the plurality of piezoelectric unit cells on a second side of the piezoelectric layers opposite the first side are formed integrally together.

[0074] In Example 6, the subject of Example 4 or 5 may optionally further include at least one piezoelectric unit cell having electrodes on opposite sides of its piezoelectric layer, each of which is formed separately from the electrodes of each other piezoelectric unit cell.

[0075] In Example 7, the subject matter of Example 2 and one of Examples 3 to 6 may optionally further include that a piezoelectric unit cell is provided at a plurality of wave crests, wherein several or all of the unit cells provided at the plurality of wave crests have electrodes on the same side of their piezoelectric layers which are separately formed and electrically connected in parallel with each other, and / or wherein a piezoelectric unit cell is provided at a plurality of wave troughs, wherein several or all of the unit cells provided at the plurality of wave troughs have electrodes on the same side of their piezoelectric layers which are separately formed and electrically connected in parallel with each other.

[0076] In Example 8, the subject of Example 7 can optionally further comprise a plurality of electrically parallel-connected electrodes provided at the wave crests and a plurality of electrically parallel-connected electrodes provided in the wave troughs, wherein the electrodes provided at the wave crests and connected electrically in parallel with each other are connected electrically in series with the electrodes provided in the wave troughs and connected electrically in parallel with each other.

[0077] In Example 9, the subject matter of Example 8 can optionally further feature that the majority of the wave crests, at which the majority of the electrically parallel-connected electrodes are provided, are arranged successively in the radial direction of the membrane, and wherein the majority of the wave troughs, in which the majority of the electrically parallel-connected electrodes are provided, are arranged successively in the radial direction of the membrane, and wherein optionally the parallel-connected electrodes provided at the majority of the wave crests and the parallel-connected electrodes provided in the majority of the wave troughs, which are electrically connected in series, are offset from one another in the circumferential direction of the membrane, optionally without overlap.

[0078] In Example 10, the subject of Example 9 may optionally further include a radially extending connecting electrode in the circumferential direction between the parallel-connected electrodes provided at the majority of the wave crests and the parallel-connected electrodes provided at the majority of the wave troughs, through which the parallel-connected electrodes provided at the majority of the wave crests are electrically connected in series with the parallel-connected electrodes provided at the majority of the wave troughs.

[0079] In Example 11, the subject matter of Example 5 and one of Examples 9 or 10 may optionally further include that the piezoelectric unit cells corresponding to the majority of the electrodes provided at the wave crests and connected electrically in parallel to one another have a common first reference electrode on a side of the respective piezoelectric layers facing away from the parallel electrodes, and that the piezoelectric unit cells corresponding to the majority of the electrodes provided in the wave troughs and connected electrically in parallel to one another have a common second reference electrode on a side of the respective piezoelectric layers facing away from the parallel electrodes, wherein the first reference electrode and the second reference electrode are formed separately from one another and are arranged circumferentially around the membrane, optionally without overlap.are arranged in a staggered pattern.

[0080] In Example 12, the subject of one of Examples 1 to 11 may optionally further have the piezoelectric layers of a plurality of piezoelectric unit cells formed in one piece.

[0081] In Example 13, the subject of one of Examples 1 to 12 may optionally further have the piezoelectric layers of a plurality of piezoelectric unit cells formed separately from one another.

[0082] In Example 14, the subject of one of Examples 1 to 13 may optionally further have that the corrugated section has a corrugated support different from the piezoelectric unit cells, wherein the support is optionally formed from a non-piezoelectric material.

[0083] In Example 15, the object of one of Examples 1 to 14 may optionally further have that at least one wave crest and at least one wave trough have a substantially circular or circular segment shape and are optionally concentric.

[0084] In Example 16, the subject of Example 2 and one of Examples 3 to 15 may optionally further have a plurality of wave crests and a plurality of wave troughs, which are provided alternately in succession in the radial direction of the membrane.

[0085] In Example 17, the subject of Examples 15 and 16 may optionally further exhibit that the majority of wave troughs and / or the majority of wave crests have a substantially circular or circular-segment shape and are optionally concentric.

[0086] In Example 18, the subject of Example 2 and of any of Examples 3 to 17 may optionally further include a plurality of wave crests and a plurality of wave troughs, each having a substantially radial principal extent and being provided alternately in succession in the circumferential direction of the membrane.

[0087] In Example 19, the object of one of Examples 1 to 18 may optionally further have the membrane designed as a closed component which is free of fluid passage openings.

[0088] Example 20 is a microelectromechanical pressure sensor comprising a microelectromechanical transducer according to one of Examples 1 to 19.

[0089] Example 21 is a microelectromechanical accelerometer comprising a microelectromechanical transducer according to one of Examples 1 to 19, wherein an inertial mass is optionally provided on the diaphragm of the transducer, which is further optionally formed separately from the diaphragm.

[0090] Example 22 is a microelectromechanical microphone comprising a microelectromechanical transducer according to one of Examples 1 to 19.

[0091] Example 23 is a microelectromechanical loudspeaker comprising a microelectromechanical transducer according to one of Examples 1 to 19.

[0092] Example 24 is a method for manufacturing a microelectromechanical transducer according to any one of Examples 1 to 19, comprising: forming a negative mold for the membrane, which has a side complementary to one side of the membrane with at least one wave crest and at least one wave trough, forming the membrane on the side of the negative mold, which has at least one wave crest and at least one wave trough, and forming a piezoelectric unit cell at at least one wave crest of the membrane and a piezoelectric unit cell in at least one wave trough of the membrane.

[0093] In Example 25, the subject of Example 24 may optionally further include the formation of the negative shape comprising: forming the at least one trough of the negative shape and the at least one crest of the negative shape in a substrate, optionally: depositing a sacrificial material layer onto a substrate and forming the at least one trough of the negative shape and the at least one crest of the negative shape in the sacrificial material layer or in the sacrificial material layer and the substrate.

[0094] In Example 26, the subject of Example 25 may optionally further include the formation of at least one wave trough of the negative shape and at least one wave crest of the negative shape, forming at least one recess in the substrate and / or in the sacrificial material layer.

[0095] In Example 27, the object of one of Examples 24 to 26 may optionally further include the formation of the membrane: depositing a layer of a piezoelectric and / or a non-piezoelectric material onto the negative mold.

[0096] In Example 28, the subject matter of one of Examples 24 to 27 may optionally further include the formation of the piezoelectric unit cells comprising: depositing a layer of a piezoelectric material onto the at least one crest of the negative shape or the membrane and depositing a layer of a piezoelectric material into the at least one trough of the negative shape or the membrane, wherein the piezoelectric layers of a plurality of piezoelectric unit cells are formed integrally or separately from one another.

[0097] In Example 29, the subject matter of Example 28 may optionally further include the formation of the piezoelectric unit cells further comprising: depositing an electrically conductive layer on the at least one wave crest of the negative shape or the membrane and depositing an electrically conductive layer in the at least one wave trough of the negative shape or the membrane, wherein the electrically conductive layers of a plurality of piezoelectric unit cells are formed integrally with one another or separately from one another.

[0098] In Example 30, the object of one of Examples 24 to 29 may optionally further include: the removal of part of the negative mold to form a holder supporting the membrane.

Claims

[1] Microelectromechanical transducer (100; 600; 700), comprising a movable membrane (104; 204; 304; 404; 504; 604; 704), which has a corrugated section (106; 206; 606; 706) with at least one trough (110; 210; 410; 610; 710) and at least one crest (108; 208; 408; 608; 708), wherein in at least one trough (110; 210; 410; 610; 710) and at least one crest (108; 208; 408; 608; 708) a piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) is provided, wherein each piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) has a piezoelectric layer (114; 214; 314; 414; 514) and at least one electrode (116; 216, 224; 316, 317; 416, 424; 516, 517; 616a, 616b-T, 616b-B, 616c, 624a, 624b, 624c) in electrical contact with the piezoelectric layer (114; 214; 314; 414; 514), wherein the membrane (104; 204; 304; 404; 504; 604; 704) is designed as a planar component which has a significantly greater extent in a first and a second spatial direction (X, Y), which are orthogonal to each other, than in a third spatial direction (A), which is orthogonal to the first and the second spatial direction (X, Y) and defines an axial direction (A) of the membrane (104; 204; 304; 404; 504; 604; 704), wherein the membrane (104; 204; 304; 404; 504; 604; 704) has a neutral fiber (NF) in the corrugated section (106; 206; 606; 706) which is located in the axial direction (A) between the at least one wave crest (108; 208; 408; 608; 708) and the at least one wave trough (110; 210; 410; 610; 710), wherein the piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) provided at the at least one wave crest (108; 208; 408; 608; 708) and the piezoelectric unit cell (112; 212; 312; 412; 512; 612; 712) provided in the at least one wave trough (110; 210; 410; 610; 710) are arranged relative to each other without overlap, wherein at least one wave crest (108; 208; 408; 608) and at least one wave trough (110; 210; 410; 610) are provided consecutively in a radial direction (R) of the membrane (104; 204; 304; 404; 504; 604). or wherein at least one wave crest (208; 408; 708) and at least one wave trough (210; 410; 710) are provided consecutively in a circumferential direction (C) of the membrane (204; 304; 404; 504; 704). [2] Microelectromechanical transducer according to claim 1, wherein the corrugated section (106; 206; 606) has a plurality of wave crests (108; 208; 408; 608) and / or a plurality of wave troughs (110; 210; 410; 610). [3] Microelectromechanical transducer according to claim 1 or 2, wherein at least one piezoelectric unit cell (112) has an electrode (116) on only one side of its piezoelectric layer (114), wherein optionally several piezoelectric unit cells (112) have an electrode (116) on only one side of their respective piezoelectric layers (114), wherein the electrodes (116) of different piezoelectric unit cells (112) are formed separately from each other. [4] Microelectromechanical transducer according to any one of claims 1 to 3, wherein at least one piezoelectric unit cell (212; 312; 412; 512; 612) has electrodes (216, 224; 316, 317; 416, 424; 516, 517; 616a, 616b-T, 616b-B, 616c, 624a, 624b, 624c) on opposite sides of its piezoelectric layer (214; 314; 414; 514). [5] Microelectromechanical transducer according to claim 4, wherein a plurality of piezoelectric unit cells (212; 412; 612) have electrodes (216, 224; 416, 424; 616a, 616b-B, 616b-T, 616c, 624a, 624b, 624c) on opposite sides of their piezoelectric layers (214; 414), wherein the electrodes (216; 416; 616a, 616b-B, 616b-T, 616c) of the plurality of piezoelectric unit cells (212; 412; 612) are formed separately from one another on a first side of the piezoelectric layers (214; 414) and the electrodes (224; 424; 624a, 624b, 624c) of the majority of piezoelectric unit cells (212; 412; 612) are formed in one piece on one of the second sides of the piezoelectric layers (214; 414) opposite the first side. [6] Microelectromechanical transducer according to claim 4 or 5, wherein at least one piezoelectric unit cell (312; 512) has electrodes (316, 317; 516, 517) on opposite sides of its piezoelectric layer (314; 514), each of which is formed separately from electrodes (316, 317; 516, 517) of each other piezoelectric unit cell (312; 512). [7] Microelectromechanical transducer according to claim 2 and one of claims 3 to 6, wherein a piezoelectric unit cell (112; 212; 412; 612) is provided at each of a plurality of wave crests (108; 208; 408; 608b, 608c), wherein several or all of the unit cells (112; 212; 412; 612) provided at the plurality of wave crests (108; 208; 408; 608b, 608c) have electrodes (116; 216; 416; 616b-B, 616c) on the same side of their piezoelectric layers (114; 214; 414), which are formed separately from each other and are connected electrically in parallel with each other, and / or wherein in a plurality of wave troughs (110; 210; 410; 610a, 610b) each provides a piezoelectric unit cell (112; 212; 412; 612), wherein several or all of the unit cells (112; 212; 412; 612) provided in the plurality of wave troughs (110; 210; 410; 610a, 610b) are each on the same side of their piezoelectric layers (114; 214;414) Electrodes (116; 216; 416; 616a, 616b-T) which are formed separately from each other and are connected electrically in parallel.; [8] Microelectromechanical transducer according to claim 7, comprising a plurality of electrically parallel connected electrodes (616b-B, 616c) provided at the wave crests (608b, 608c) and a plurality of electrically parallel connected electrodes (616a, 616b-T) provided in the wave troughs (610a, 610b), wherein the electrodes (616b-B, 616c) provided at the wave crests (608b, 608c) and connected electrically in parallel with each other are electrically connected in series with the electrodes (616a, 616b-T) provided in the wave troughs (610a, 610b). [9] Microelectromechanical transducer according to claim 8, wherein the majority of wave crests (608b, 608c), at which the majority of the electrically parallel-connected electrodes (616b-B, 616c) are provided, are arranged successively in the radial direction (R) of the membrane (604), and wherein the majority of wave troughs (610a, 610b), in which the majority of the electrically parallel-connected electrodes (616a, 616b-T) are provided, are arranged successively in the radial direction (R) of the membrane (604), optionally the parallel-connected electrodes (616b-B, 616c) provided at the majority of the wave crests (608b, 608c) and the parallel-connected electrodes (616a, 616b) provided in the majority of the wave troughs (610a, 610b) 616b-T), which are electrically connected in series, offset from each other in the circumferential direction (C) of the membrane (604), optionally without overlap. [10] Microelectromechanical transducer according to claim 9, wherein in the circumferential direction (C) between the parallel-connected electrodes (616b-B, 616c) provided at the majority of the wave crests (608b, 608c) and the parallel-connected electrodes (616a, 616b-T) provided at the majority of the wave troughs (610a, 610b) a connecting electrode (617V-1, 617V-2) extending in the radial direction (R) is provided, via which the parallel-connected electrodes (616b-B, 616c) provided at the majority of the wave crests (608b, 608c) are electrically connected in series with the parallel-connected electrodes (616a, 616b-T) provided at the majority of the wave troughs (610a, 610b). [11] Microelectromechanical transducer according to claim 5 and one of claims 9 or 10, wherein the piezoelectric unit cells (612) corresponding to the majority of the electrodes (616b-B) provided at the wave crests (608b) and connected electrically in parallel to each other have a common first reference electrode (624b) on a side of the respective piezoelectric layers facing away from the parallel-connected electrodes (616b-B) and wherein the piezoelectric unit cells (612) corresponding to the majority of the electrodes (616a) provided in the wave troughs (610a) and connected electrically in parallel to each other have a common second reference electrode (624a) on a side of the respective piezoelectric layers facing away from the parallel-connected electrodes (616a), wherein the first reference electrode (624b) and the second reference electrode (624a) are formed separately from each other and are arranged offset from each other in the circumferential direction (C) of the membrane (604), optionally without overlap. [12] Microelectromechanical transducer according to any one of claims 1 to 11, wherein the piezoelectric layers (114; 214; 314) of a plurality of piezoelectric unit cells (112; 212; 312; 712) are formed in one piece together. [13] Microelectromechanical transducer according to one of claims 1 to 12, wherein the piezoelectric layers (414; 514) of a plurality of piezoelectric unit cells (412; 512) are formed separately from each other. [14] Microelectromechanical transducer according to any one of claims 1 to 13, wherein the corrugated section has a corrugated support (426) different from the piezoelectric unit cells (412; 512), wherein the support (426) is optionally formed from a non-piezoelectric material. [15] Microelectromechanical transducer according to any one of claims 1 to 14, wherein at least one wave crest (108; 208; 408; 608) and at least one wave trough (110; 210; 410; 610) have a substantially circular or circular segment shape and are optionally concentric. [16] Microelectromechanical transducer according to claim 2 and any one of claims 3 to 15, comprising a plurality of wave crests (108; 208; 408; 608) and a plurality of wave troughs (110; 210; 410; 610) which are provided alternately in the radial direction (R) of the membrane (104; 204; 304; 404; 504; 604). [17] Microelectromechanical transducer according to claims 15 and 16, wherein the plurality of wave troughs (110; 210; 410; 610) and / or the plurality of wave crests (108; 208; 408; 608) have a substantially circular or circular segment shape and are optionally concentric. [18] Microelectromechanical transducer according to claim 2 and according to any one of claims 3 to 17, comprising a plurality of wave crests (708) and a plurality of wave troughs (710), each having a substantially radial main extent and being provided alternately in the circumferential direction (C) of the membrane (704). [19] Microelectromechanical transducer according to any one of claims 1 to 18, wherein the membrane (104; 204; 304; 404; 504; 604; 704) is designed as a closed component which is free of fluid passage openings. [20] Method for manufacturing a microelectromechanical transducer according to any one of claims 1 to 19, comprising: Forming a negative shape (1000) for the membrane, which has a side (1001) complementary to one side of the membrane with at least one wave crest (1010) and at least one wave trough (1012), Forming the membrane (1021) on the side of the negative shape (1000), which has at least one wave crest (1020) and at least one wave trough (1018), and Forming a piezoelectric unit cell at at least one wave crest (1020) of the membrane (1021) and a piezoelectric unit cell in at least one wave trough (1018) of the membrane (1021). [21] Method according to claim 20, wherein forming the negative mold (1000) comprises: Forming at least one wave trough (1012) of the negative shape (1000) and at least one wave crest (1010) of the negative shape (1000) in a substrate (1002), optional: Depositing a sacrificial material layer (1004) onto a substrate (1002) and forming at least one trough (1012) of the negative shape (1000) and at least one crest (1010) of the negative shape (1000) in the sacrificial material layer (1004) or in the sacrificial material layer (1004) and the substrate (1002). [22] Method according to claim 21, wherein the formation of the at least one wave trough (1012) of the negative shape (1000) and the at least one wave crest (1010) of the negative shape (1000) comprises the formation of at least one recess in the substrate (1002) and / or the sacrificial material layer (1004). [23] Method according to any one of claims 20 to 22, wherein forming the membrane (1021) comprises: Deposition of a layer (1016) of a piezoelectric and / or a non-piezoelectric material onto the negative mold (1000). [24] Method according to any one of claims 20 to 23, wherein the formation of the piezoelectric unit cells comprises: depositing a layer (1016) of a piezoelectric material onto the at least one wave crest (1010, 1020) of the negative shape (1000) or the membrane (1021) and depositing a layer (1016) of a piezoelectric material into the at least one wave trough (1012, 1018) of the negative shape (1000) or the membrane (1021), wherein the piezoelectric layers (1016) of a plurality of piezoelectric unit cells are formed integrally with one another or separately from one another, optionally, the formation of the piezoelectric unit cells further features: Deposition of an electrically conductive layer (1014) onto at least one wave crest (1010, 1020) of the negative mold (1000) or the membrane (1021) and Deposition of an electrically conductive layer (1014) into the at least one wave trough (1012, 1018) of the negative shape (1000) or the membrane (1021), wherein the electrically conductive layers (1014) of a plurality of piezoelectric unit cells are formed integrally with one another or separately from one another. [25] Method according to any one of claims 20 to 24, further comprising: removing a part of the negative mold (1000) to form a holder (1030) supporting the membrane (1021).

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